Management Information Systems Assignment Report

115. 107 Management Information Systems Assignment Report Contents Part 1 – ER Diagram2 Part 2 – Tables and Keys3 Part 3 – Queries4 Part 4: Spreadsheet filters and pivot tables7 List of Figures Figure 1 – ER diagram for event management system of hotel2 Figure 2 – Query 1 QBE for staff allocation4 Figure 3 – Query 1 output for staff allocation4 Figure 4 – Query 2 QBE for scheduled events beginning of October5 Figure 5 – Query 2 output for scheduled events beginning of October5 Figure 6 – Query 2 database report for scheduled events beginning of October6Figure 7 – Query 3 QBE for total number of registered participants6 Figure 8 – Query 3 output for total number of registered participants7 Figure 9 – Spreadsheet data with no filers or conditional formatting applied7 Figure 10 – Spreadsheet with the â€Å"show only events commencing after 15th October filter applied7 Figure 11 – Spreadshe et with the ‘show only events commencing after 1st November as underlined' conditional formatting applied8 Figure 12 – Pivot table8 Figure 13 – Pivot table as a bar chart8 List of TablesTable 1 – Attributes for ER diagram for event management system of hotel2 Table 2 – Attributes for ER diagram for event management system of hotel3 Part 1 – ER Diagram StaffMember Venue Event Registration Attendee Reserved for Manages Accept Makes Applies to 1.. * 1.. * 1 1 1 0.. * 0.. * 0.. * 0.. * Payment Accept 0.. * 0.. * 1 Gains entry Client System Presents 0.. * Record Details 1 0.. * Inputs 1.. * 1.. * Figure [ 1 ] – ER diagram for event management system of hotel Table [ 1 ] – Attributes for ER diagram for event management system of hotel Entity Type| Attributes| Key attribute|Venue| venueID, venueCapacity, venueDescription| venueID| Event| eventID, eventName, eventType, startDate, endDate, startTime, endTime, availableSpaces, eventFee| e ventide| StaffMember| staffID, firstName, lastName, jobTitle | staffID| Registration | registrationID, registrationDate, eventID | registrationID| Attendee| attendeeID, firstName, lastName, title, companyName, contactAddress, phoneNo | attendeeID| Payment| paymentAmount, paymentDate, paymentType, paymentCredit, creditcardID, creditcardName, creditcardExpiry| paymentID| Client| clientName, companyName, contactAddress, contactPhone, clientIndustry, clientNeeds| clientID| System| systemClient, systemAttendee, systemVenues, systemInvoice, | systemID| Part 2 – Tables and Keys Table [ 2 ] – Attributes for ER diagram for event management system of hotel Table| Column| Primary Key| Comments|VenueTbl| venueID, venueCapacity, venueDescription| venueID| | EventTbl| eventID, eventName, eventType, startDate, endDate, startTime, endTime, availableSpaces, eventFee, staffID| eventID| staffID is a foreign key into StaffMemberTbl. | StaffMemberTbl| staffID, firstName, lastName, jobTitle | staffID| | RegistrationTbl| registrationID, registrationDate ,eventID, attendeeID| registrationID| eventID is a foreign key into EventTbl while attendeeID is a foreign key into AttendeeTbl| AttendeeTbl| attendeeID, firstName, lastName, title, companyName, contactAddress, phoneNo, eventID, registrationID| attendeeID| RegistrationID is a foreign key into RegistrationTbl while event ID is a foreign key into EventTbl. ReservedforTbl| eventID, venueID, attendeeID, | reserveID| eventID is a foreign key into EventTbl while attendeeID is a foreign key into AttendeeTbl| Part 3 – Queries Query 1 -StaffAllocation Figure [ 2 ] – Query 1 QBE for staff allocation Figure [ 3 ] – Query 1 output for staff allocation Query 2 – YearEndSchedule Figure [ 4 ] – Query 2 QBE for scheduled events beginning of October Figure [ 5 ] – Query 2 output for scheduled events beginning of October **For unknown reasons, event 9, 16 & 17 is not listed in the search result e ven when the date falls within the range as set out in the criteria. I have attempted to modify the criteria selection to cover between the date range of 30/09/2011 – 01/01/2050 etc but it has still failed to come up. Query 2 – Year End ReportFigure [ 6 ] – Query 2 database report for scheduled events beginning of October Query 3 – Registration Numbers Figure [ 7 ] – Query 3 QBE for total number of registered participants Figure [ 8 ] – Query 3 output for total number of registered participants Part 4: Spreadsheet filters and pivot tables Figure [ 9 ] – Spreadsheet data with no filTers or conditional formatting applied Figure [ 10 ] – Spreadsheet with the show only events commencing after 15th October filter applied Figure [ 11 ] – Spreadsheet with the ‘show only events commencing after 1st November as underlined' conditional formatting applied Figure [ 12 ] – Pivot table Figure [ 13 ] – Pivot table a s a bar chart

Eyewitness Testimony as a Source of Reliable Evidence

Eyewitness Testimony as a source of reliable evidence In relation to cognitive psychology, is eyewitness testimony reliable in today’s judicial system? Word Count: 3944 ABSTRACT Is eyewitness testimony a reliable source of evidence in today’s judicial system? Many jurors tend to pay close attention to eyewitness testimony assuming that what they hear is exactly as it happened. They ignore the psychology behind remembering an event. Our brain is a complex structure and it is difficult to absorb every stimulus in our surrounding. We pay great attention to some aspects of a situation while completely ignoring others. It is advisable for expert psychologists to be present during a court case that involves eyewitness testimony, as they are more aware of its flaws. We store information in schemas and when we gain new knowledge it is altered in order to fit these schemas. Leading psychologists such as Elizabeth Loftus, Neil Bartlett and Yullie & Cutshall have carried out research in order to demonstrate how our memory can be altered by psychological factors such as leading questions, reconstructive memory and weapon focus. This research paper contains a vast number of experiments and studies done in order to illustrate the unreliability of our memory and whether courts should rely on eyewitness testimony as a prime source. Age and gender also serve as factors that influence eyewitness testimony. Through research and analysis, it is concluded in this paper that eyewitness testimony should not be given superiority over other actual evidence presented, as our memory is the least reliable source. It is worthwhile to carry out further investigation about the case if eyewitness testimony is the only evidence available, as false testimonies could lead to an innocent individual being charged guilty. Word Count: 260 CONTENTS Abstract †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. Page 2 Introduction †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. Page 4 Discussion†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚ ¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. Page 7 Misleading Questions†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ Page 7 Anxiety and Stress†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. Page 9 Weapon Focus†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ Page 11 Reconstructive Memory†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. Page 11 Confident Testimony†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. Page 14 Age†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. †¦Ã¢â‚¬ ¦ Page 15 Gender†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã ¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. Page 16 Conclusion†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ Page 17 References †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. Page 19 INTRODUCTION The reliability of eyewitness testimony has often been questioned in cases of crime and violence but yet the judicial syste m seems to ignore its flaws. Numerous psychologists have carried out experiments and studies regarding this issue. Eyewitness testimony has a large psychological background that judges, lawyers and the jury seem to ignore. Our ability to remember certain situations and events may be distorted according to the time and place that the event occurred or the time and place that the eyewitness testimony is given. Cognitive psychologists have carried out profound research about this phenomenon and have found that eyewitness testimony can be related to human schemas, reconstructive memory and our ability to remember. The knowledge we have gained from the world is stored in our brain as an organized package of information called a schema. The ‘schema theory’ states that the knowledge we have already gained through our life has a major influence on what we remember. According to Cohen (1986) as cited in Gross (64), the human mind uses past experiences in order to deal with new experiences. Our behavior is guided by the set of schemas that we have in our brain. The new experiences that we face are not just ‘replicated’ into our memory but instead are reconstructed in order to fit our schemas. The reconstruction of memory is an active process and happens throughout our life (Gross, 64). Therefore, how we perceive an event is strongly influenced by our past experiences. Human memory is seen as an unreliable source when we apply the idea of reconstructive and interpretative nature of memory to eyewitness testimony. The probability of people being wrongly accused increases as the importance of eyewitness testimony in the cases of accidents and crimes increases, and therefore the guilty do not come to justice (Gross, 64). Many experiments conclude that law professionals and judges rely and place their decisions on eyewitness testimony, however, researchers investigated on situations whereby the innocent had been accused. As cited in Miller’s article (2006), Gary Wells (1998) researched on forty such cases and with the help of DNA testing it was found that all forty convicted suspects were actually innocent. The witnesses wrongfully accused the suspects in thirty-six of these cases. The human brain has a limited capacity to deal with the incoming information but yet every moment we encounter a large variety of stimuli like sights, sounds and smells. However, as mentioned above if we encounter stimuli which conflict with our schemas, we reconstruct our memory in order to fit our chemas. The human brain therefore focuses on some aspects of the situation while ignoring the others in order to cope with the sensory barrage. This process of choosing stimuli is called selective attention. Eyewitnesses tend to collect information that relates to their interests and may ignore other vital aspects of the event (Glassman, 5). It is difficult for witnesses to reconsider their initial understanding once the y have stated facts in a specific way or have already indentified an individual as the performer, due to the reconstruction of their memory (e. . once an eyewitness recognizes an individual in a line-up it is likely for them to recognize the same individual in later line-ups even though that individual may not be the performer). Jury’s place great reliance on eyewitness testimony and ignore the dangers of false memories (Engelhardt, n. d). In view of these findings, this work will investigate the â€Å"extent to which eyewitness testimony is reliable in today’s judicial system† focusing on major factors that influence our memory and ability to remember. Cognitive psychology plays a major role in this investigation as it involves the idea of memory and schemas. DISCUSSION â€Å"An account given by people of an event they have witnessed† (Eyewitness Testimony Psychology) is usually referred to as an eyewitness testimony. One may be asked to recall the event they witnessed and describe what happened. Jury’s tend to find eyewitness testimony to be a reliable source of information and pay close attention to it, but the witness may have had a hard time remembering the event and the testimony could be inaccurate. Research done by a number of psychologists regarding eyewitness testimony found that it could be affected by many psychological factors such as leading questions, anxiety and stress, weapons and reconstructive memory (Eyewitness Testimony Psychology). Factors such as age and gender could also affect the way in which individuals remember events. Influence of psychological factors on eyewitness testimony Misleading questions American psychologist, Elizabeth Loftus, represented the application of Cognitive psychology to the real world. Her experiments demonstrated how misleading information could cause eyewitnesses to reconstruct their memories (Gross, 64). A leading question is a question that contains information previously unknown to the witness. In one of her studies with Palmer (Loftus and Palmer, 1974) as cited in the article Memory (Psychology), the participants watched a videotape that showed an automobile accident consisting of two cars. After watching the videotape the participants were presented with a questionnaire whereby the question was altered for groups of participants. One question asked, â€Å"About how fast were the cars going when they hit each other? † For other participants the verb ‘hit’ was replaced by ‘smashed’, ‘collided’, ‘bumped’, or ‘contacted’. Even though all participants viewed the same videotape, their speed estimates differed considerably depending on how the question was asked. When the verb ‘contacted’ was used, the average speed estimate was 32 mph, when the verb was ‘hit’ it was 34 mph, 38mph when it was ‘bumped’, 39 mph when it was ‘collided’, and 41 mph when it was smash. Loftus carried out a follow up study a week later whereby she asked the participants whether there was any broken glass in the videotape. Participants that were presented with the verb ‘smashed’ were twice as likely to ‘remember’ any broken glass than the participants that were presented with the verb ‘hit’. The information that came in much later after the original event had occurred incorporated with that event, hence causing the original even to be remembered in a different way. The introduction of false signs misrepresented the participants’ memories (Memory (Psychology)). The power of misleading questions is demonstrated in the above study by Loftus & Palmer. An answer is determined by how the question is asked. The tendency to distort one’s memory of an event when later exposed to misleading information about it is known as the misinformation effect. The witness’s memory could be affected by questions asked by the police, friends or attorneys. Reconstruction of memory could also take place if information about the case or crime comes in weeks or months later. This may change what the witness has to say on the witness stand (Memory (Psychology)). The questions and information presented in the courtroom may cause the witness to remember the incident differently and the eyewitness testimony becomes inaccurate. Leading questions lead to the reconstruction of memory in order for the new information to fit into our already existing schemas. Leading questions therefore have the tendency to make eyewitness testimony unreliable in today’s judicial system. It is important for lawyers to know about the consequences of these questions and therefore construct their questions well. Anxiety and stress Along with leading questions it is said that anxiety and stress is a psychological factor that affects eyewitness testimony. Some researchers have questioned whether attentional focus is a reason that causes poor recall of a violent incident. Clifford and Scott (1978) as cited in the article Eyewitness Testimony Psychology, found that when individuals witness a rather violent incident they seem to remember less than individuals who witness a non-violent incident. They carried out a study whereby they presented a film with violent attacks to a group of participants. The control group who saw a less violent version of the film remembered more of the forty items about the event than the participants. The control group was not exposed to very stressful conditions as compared to the participants. Although this may have not been a real-life situation, the memory of the participants was affected by anxiety. An increase in anxiety and autonomic arousal is caused by violent incidents that in turn have a disadvantageous effect on memory. On the other hand, a study carried out by Yullie and Cutshall (1986) (as cited in the article Eyewitness Testimony Psychology) contradicts Clifford and Scott’s findings. The research gathered by Yullie and Cutshall was that of a real-life situation hence making their data more accurate. The researchers showed that individuals had accurate memories when they witnessed a stressful event up close. The event was of a shooting just outside a gun shop in Canada. The scene witnessed was of a criminal who robbed the gun shop off guns and money but eventually was shot six times and died on the spot. Straight after this shooting had taken place, the police asked to interview thirteen individuals who were there at the time of the event and had witnessed it. Five months later these same thirteen individuals were interviewed again. It was found that the recall was still as accurate as it was five months after witnessing the event. The two misleading questions that were presented by the police did not affect their memories or alter their testimony. However, one limitation to this study was that the witnesses interviewed were at different distances from the scene and the ones that were the closest went through a greater level of stress and this in turn may have assisted with their ability to remember the event vividly (Eyewitness Testimony Psychology). Through both the studies carried out about anxiety and memory recall we can say that experiments carried out under laboratory conditions may not give the same results as when it is a real-life situation. Memory recall of a real-life situation is accurate even after a few months and the loaded questions do have as much of an effect as they do in laboratory experiments (e. g Loftus & Palmer, 1974) (Eyewitness Testimony Psychology). The above information gives a re-assurance that eyewitness testimony is not completely unreliable depending on the situation and the witness’s role in the event. There may be some situations where memory distortions take place and other situations where they do not. Whether memory distortion or reconstruction takes place or not depends on the witness’s state of mind at the time of the event. The emotional state of the individual may cloud their reason, judgment and perception; therefore it is necessary to be neutral and unbiased when witnessing a crime scene. Weapon Focus The study by Yullie and Cutshall (1986) also relates to ‘weapon focus’ as a psychological factor that affects eyewitness testimony. When weapons are involved the witness is less likely to remember details about the riminal but is more likely to remember the details of the weapon (Eyewitness Testimony Psychology). An experiment conducted by Johnson and Scott (1976) as cited in Loftus et al (56) illustrated this phenomenon. In the ‘no weapon’ condition participants overheard a mild conversation in the next room about an equipment failure, witne ssed a confederate enter the room with a grease pen, watched him utter a single line and leave. In the ‘weapon’ condition the participants overheard a violent conversation along with crashing objects, saw a confederate enter the room with a bloodied letter opener, watched him utter a single line and then leave. Participants in both condition witnessed the target individual for four seconds. It was found that 33% of the participants in the ‘bloody letter opener’ condition identified the culprit correctly and 49% of the participants in the greasy pen condition identified the culprit correctly. A reduced ability to remember the confederate was associated with the presence of a weapon. Jury’s should take into account whether or not weapons were involved in the crime. This is because the eyewitness will be less likely to recognize the criminal and an innocent individual may be held guilty. Our attention is usually drawn to the weapon and we ignore what else may be happening in our surroundings. Reconstructive Memory The reliability of eyewitness testimony can yet be argued through reconstructive memory. As mentioned earlier reconstructive memory is another one of the many psychological factors that has an effect on eyewitness testimony. Psychologist Neil Bartlett played a key role in associating reconstructive memory to eyewitness testimony as he stated that ‘recall is subject to personal interpretation dependent on our learnt or cultural norms and values’. We have already established the fact that the human memory alters according to the way in which we store information in our brain, it is not stored exactly as it seems to be; different people interpret a situation differently and therefore store it in a way that makes sense to them. The brain stores information in schemas, but these schemas are able to distort unconsciously ‘unacceptable’ and unfamiliar knowledge in order to ‘fit in’ with the already stored information or schemas that we have which n turn results in unreliable eyewitness testimony (Eyewitness Testimony Psychology). Bartlett’s research about reconstructive memory found that â€Å"memory is an active process and subject to individual interpretation or construction† (Eyewitness Testimony Psychology). War of the Ghosts, (Bartlett (1932) as cited in Eyewitness Testimony Psychology) was his most famous study whereby he tried to show that we attempt to link what we remember with our e xisting schemas. In other words, our memory is not just an accurate footage of what has happened but it is what we make of it. Bartlett mentioned that we usually involuntarily modify our memories so they make more sense to us. In the study Bartlett’s participants heard a story and had to re-tell the story to another person. The story was a North American folktale called ‘The War of the Ghosts’. When the participants were asked to recount the details of the story, each individual seemed to tell it in their own individual way. As the participants re-told the story, it became shorter, puzzling ideas were rationalized or omitted altogether and details changed to become more conventional or familiar. The information about the ghosts was omitted as it was difficult to explain and participants recurrently recalled the idea of â€Å"not going because he hadn’t told his parents where he was going†, as that circumstance was more familiar to them. Through the above study Bartlett was able to conclude that our memory is distorted by the existing knowledge and schemas we have in the human brain. Therefore, it seems that each individual reconstructs their memory to conform to their individual values and attitudes towards the world. This is a clear indication that our memories are anything but reliable. How we view and remember things depends on our ethics, culture, belief and past experiences. Also through reconstructive memory we make hasty generalizations basing information on what we ‘think’ may have happened due to the information we already have stored. We shape and assemble the incident according to our stereotypes and expectations. This can further be elaborated through a study by Allport and Postman (1947) as cited in Jarvis & Russell (131), whereby they presented participants with a picture of a scruffy white man threatening a smart black man with a razor. Later when the participants were told to recall the picture they recalled that a scruffy black man was threatening a smart white man with a razor. This fitted in with the American stereotypes of that time; the participants reconstructed their memory according to their expectations. We can say that reconstructive memory is yet another reason that makes eyewitness testimony unreliable; however, some psychologists do believe that schema theory exaggerates the inaccuracy of memory. It cannot predict what and how people remember, as we do not know which schemas are being used. The study by Allport and Postman also ties down into another way our cognitive system introduces error, which is by the means of inference. Inference emphasizes on how humans tend to make assumptions past the literal meaning. Many memory distortions are a part of this inference whereby what the eyewitness says to have witnessed is not what was perceived but a mere extension of it, hence, leading to an inaccurate recall of the event or incident (Glassman, 440) Flaws of the eyewitness as an individual Confident Testimony Confident testimony is yet another flaw that tends to put innocent people in jail. When the witnesses say with absolute confidence that ‘this is the guy that did it†¦ I will never forget that face’, it is difficult to argue with their beliefs. Confidence is a strong characteristic and although people may make mistakes with their testimony the way in which they give their testimony has a strong outcome on the jury. It becomes difficult to question their evidence and discredit their feelings after knowing that the witness went through a horrible crime especially when they give their testimony with absolute assurance. Jurors will usually believe them. A major flaw that Elizabeth Loftus points out is that judges do not usually use the help of experts in order to bear out to the jury about the flaws of eyewitness testimony. It would be helpful to have a few cognitive psychologists as part of the jury in order to point out the factors that affect eyewitness testimony; however some judges will allow this while others will not. Jury’s that are unaware of the flaws of eyewitness testimony will have a larger percentile of wrongful verdicts compared to jury’s that are educated about he flaws. Elizabeth Loftus went on to explain that jury’s that are unaware of memory distortions will tend to decide their verdict from their ‘gut feeling’. Jury’s that are ignorant about these flaws rely greatly on the witness and have a propensity to discount the balance that needs to be present between the eyewitness testimony and the physical scientific evidence. Loftus also pointed out that when a witness repeatedly sees the accused they become encrypted in the victim’s memory, even if they are innocent. The victim may continually see the suspect in photos and line-ups during the duration of the investigation period and court case. This may make it possible that the witness will then not be able to recognize the true criminal anymore, especially if the crime was witnessed for a short time and the victim was not able to perceive every stimulus in the surrounding. Therefore, when the witness will testify with absolute confidence that the ‘suspect’ is the actual criminal, it will be difficult for the jury to argue (Miller, 2006). Age Psychological factors definitely play a huge role in eyewitness testimony but the characteristics of the witness also matter. Jury’s should also take into account the age and gender of the witness. Certain research has been done in order to identify the accuracy of a child’s eyewitness testimony; it is much less accurate than the adults’ testimony. This is because children are not able to give concrete answers to the questions that require much explanation. Children have less cognitive competence i. e. their information processing skills for problem solving, language and attention are undeveloped. Psychologists from University of Southampton conducted research to analyze a child’s ability to answer repeated questions during a testimony. When a child gives a testimony they are afraid to be incorrect therefore repeated questions are not beneficial when it comes to child eye-witnessing as the questions confuse them and make them think that their original story was not true. The first information provided by the child is always the best. The younger the child is, the less accurate the testimony will be. Children usually give incorrect information due to their need to be socially approved. Karpel et al (2001) as cited in Science Aid carried out research associated with age and eyewitness testimony. His aim was to see how reliable eyewitness testimony is in older people. Young adults (17 – 25) and older adults (65 – 85) were shown a video of a theft. They were then asked to recollect what they had seen in the video. The results of both age groups were compared and it was seen that the information provided by the young adults was more precise and their testimony was less likely to change when asked leading questions.. In order to ensure that information provided by elderly people is accurate it is advisable not to expose them to misleading questions as their memories are easily distorted. Also, older adults misremember context and therefore must be questioned carefully. As seen, age is another factor that affects eyewitness testimony and its reliability. It is important to know the age of the witness before moving on with the case as psychologists may have a slight idea about how reliable the provided information might be (Science Aid). Gender There has been no concrete evidence as yet that males and females have a significant difference when identifying a criminal. Research by Shapiro & Penrod (1986) as cited in Wells & Olson (280) found that females are more likely to make accurate identifications but are also more likely to make false identifications, as they are more likely to try and ‘attempt’ to identify. Due to this males and females capitulate an equal ability to identify criminals and give an eyewitness testimony. However since the male and female brains differ slightly, both genders will pay closer attention to different features of the incident, but the overall ability in eyewitness identification is impossible to tell apart. CONCLUSION Through research we have found that eyewitness testimony can be quite fallible and that there are a number of factors that seem to interfere with our memories. It is important for jury’s to be aware of these factors before placing a verdict and should not place great reliance on factors such as confidence and vivid descriptions of details. If possible, it is advisable o find other evidence rather than eyewitness testimony. A major limitation of the research investigated is that majority of the studies done in relation to eyewitness testimony are laboratory studies. This inhibits us to generalize the data collected to the real world. An implication for future research would be to carry out more interviews with individuals who have witnessed acts of crim e and violence rather than basing conclusions on laboratory studies. Also, it could be helpful to carry out research regarding a number of factors that affect eyewitness testimony (e. g. study that compares the ability to remember events when the variables are age, gender, weapons and misleading questions). The limitation presented does not change the fact that human memory is a very personal and comparative aspect and therefore cannot be a foundation for any important decisions. It is important to know that memory changes with time and every consequent attempt to recall the event will be just another skewed interpretation of the event. Eyewitnesses can refute or support the general facts about the case but the details and their testimony should not be put superior to the actual evidence presented in court. Studies have also proven that innocent people have been accused due to eyewitness testimony, this elaborates on the unreliability of it. Our ability to recall an event is affected by the information provided after the event, the level of stress and anxiety we are at during the time of the event also affects it, the presence of weapons also distorts our memory, reconstructive memory is yet another psychological factor that makes eyewitness testimony unreliable, our expectations, age and gender also play a role when giving a testimony. All these factors should be taken into consideration when the evidence provided is eyewitness testimony. The reliability of eyewitness testimony in today’s judicial system is very low and should be analyzed in depth before reaching conclusions. REFERENCES Engelhardt, L. (n. d. ). â€Å"The problem with Eyewitness Testimony†. Agora. Retrieved Jan. 02, 2010 from http://agora. stanford. edu/sjls/Issue%20One/fisher&tversky. html. Eyewitness Testimony Psychology research. (2007). Psychology Degree and A-level online resources. Retrieved Feb. 2, 2010 from http://www. simplypsychology. pwp . blueyonder. co. uk/eyewitness-testimony. html Glassman, William E. (2000). Approaches to Psychology. Buckingham, England: Open UP. Gross, Richard D. (1999). Key Studies in Psychology. London: Hodder & Stoughton. Jarvis, M. , & Russell, J. (2002). Key Ideas in Psychology. Cheltenham: Nelson Thornes. Loftus, E. F. , Loftus, G. R. , & Messo, J. (1987). Some facts about weapon focus. Law and H uman Behaviour. Memory (psychology) – MSN Encarta. (n. d. ). Retrieved Sept. 14, 2009 from http://encarta. msn. om/encyclopedia_761578303_5/Memory_(psychology). html Miller, Z. (2006, October 14). The Accuracy of Eye Witness Testimony and Its Flaws. Retrieved December 23, 2009, from http://ezinearticles. com/? The- ­Accuracy- ­of- ­Eye- ­Witness- ­Testimony- ­and- ­Its- ­Flaws&id=328261 Science aid: Eyewitness Testimony. (n. d. ) Science Aid: High School, A Level and GCSE Science. Retrieved 13 Dec. 2009 from http://scienceaid. co. uk/psychology/cognition/eyewitness. html Wells, Gary L. , & Olson, Elizabeth A. (2003). Eyewitness Testimony. Ames, Iowa: Iowa State University.

Case Study Drivers of Industry Financial Structure

Based on KR+H’s past financial performance and the cost of investment, KR+H would need additional financing to fund the proposed capital investment. The internal financing could be very difficult for KR+H based on it had a deficit in 1992. And internal financing may also slow down the investments because KR+H has to retain its profit. Also rising the price is not a very good option in a long-term perspective. Because it could retard their growth and therefore did not represent a viable path to a long-term profitability. So we suggest that KR+H should finance the proposed capital by relying on external financing from a bank or an outside investor. Context KR+H is a manufactory company that designs,fabricates and installs high quality, uniquely designed cabinetry. Now it had devised a unique operating strategy of producing high quality custom cabinets at a low cost. KR+H believes that the use of computer-controlled equipment allowed the firm to significantly reduce their labor cost and other production cost while increasing the efficiency of the manufacturing process. In order to support the development if their innovative operating system, KR+H need to clearly define the scope and speed of growth for their business. However, the partners do not have internal funds to finance the investment and their access to external capital markets is limited. Therefore KR+H needs a better operating and financial strategy to managing rapidly growth and its capital. I think the article â€Å"Seize advantage in a downturn† is very helpful. Many companies fail to see the opportunities hidden in economic downturns. In order to take advantage of opportunities, KR+H first need to do a thorough but rapid assessment of its own vulnerabilities and then move decisively to minimize them. David and Daniel, 2009) KR+H could approach their problem by using some of those steps introduced in this article such as Monitor and maximize its cash position 1. Evaluating the capital position: In the cash flow statement Exhibit 6, the net decrease in cash by $15,298 in 1991 and $46,955 in 1992. In order to meet cash requirement during 1992,KR+H gets a personal loan about $35,000 and the bank overdraft to cover its deficit abou t $14,000,which shows us that KR+H are short of cash during the past years and it gets worse. The total enhancement of the new investment will be: Category |Cost | |Require in Capital |$300,000 | | |$100,000(developing in 2 years) | |Software | | | |$25,000 – $30,000 (maintain update per year) | |Marketing |$40,000 | Based on KR+H’s past financial performance and the cost of investment, KR+H would need additional financing to fund the proposed capital investment for sure. 2. Adding investment is valuable and profitable: I think the proposed projects are profitable investments and it will add values. Because the investments will reduce costs and increase the working efficiency in manufacturing process: |Category |Number | |Increase production capacity |50% | |Labor cost saving per year |$170,000 | Another fact is that on a pro forma basis, KR+H’s cost of goods sold in 1990, the year before merged is approximately 60% of sales. In 1991,the percentage is increased to 67% and in 1992 the year after the merger the percentage rose to almost 75%. It shows us that some unanticipated cost increasing rapidly while the revenue is rising. If KR+H could adopting the new investment it would make its production more efficiently and the technique may also save some cost of goods. In addition, the cabinet industry experienced a decline in efficiency in 1992. Firm size |Sales per work |Compare to 1991 | |Large |$120,000 |gain 9% | |Medium |$84,000 |decline 11% | |Small |$80,000 |off 2% | | KR+H could gain a long-term rapid growth in sales by first adopting the new technique and the improvements in production efficiencies will give KR+H more advantages in sales. There is no doubt that the investment will increase the operating leverage and also increase risk. In Exhibit 9, with investments KR+H will yearly saving $207,900. Therefore, adding the investment is very profitable. And also rising the price is not a very good option in a long-term perspective. Because it could retard their growth and therefore did not represent a viable path to a long-term profitability. I think KR+H finance the proposed capital by relying on external financing. Because the internal financing could be very difficult for KR+H based on it had a deficit that was covered with a personal loan to company about $35,000 by a partner and a bank overdraft $14,000 in 1992. And internal financing may also slow down the investments because KR+H has to retain its profit. The investors wouldn’t want a low return just because the firm wants to invest. Thus, external funding will be a better choice. Ratios In 1992 and 1993, exhibit 4 Year |Return on Sales |Return on Equity | |1992 |2. 1% |21% | |1993 |8. 3% |98% | | Besides this, KR+H also is profitable in 1992 and assume that it will have 10% growth rate. Meanwhile, with the investments could save KR+H about $209,900 each year. Those profitable data in its financial performance will help KR+H to get a loan from a bank or other outside investors. Conclusion: KR+H has its new investments developed and they focus on reduction by continuing to increase the level of automation in the process. And this investment is valuable and profitable. Based on KR+H had performed not very well in their cash flow in the past 3 years. The company also troubled with limited access to the capital market. Therefore, it is necessary for KR+H to get external financing in order to maintain its revenue and get a rapid growth. References: Robert C. Higgins(2012), Analysis for financial management David Rhodes and Daniel Stelter(2009), Seize advantage in a downturn

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Analyzing the Statement of Cash Flows - Assignment Example Therefore, Net Income is the position of a company’s business based on matching incomes versus expenditure but cash flow will only reflect actual movement of money without any considerations for the accruals (Epstein, 2014). A comparison of the Cash from operating activities to the Net Income for techno in 2008 stands at a ratio of 177,387/242,329= 0.73 and 2009 stands at 24,525/316,354= 0.08. Therefore, Techno had a 73% rate in 2008 and it dropped to 8% in 2009. This is a low quality income showing a great imbalance. The time taken to convert any credits or accruals to cash is stretching an indication of a pending problem that may lead to crippled operations. The first red flag is the declining number of receivable from $-49,704,000 in 2008 to $-288,174,000 in 2009. This deterioration is emphasized by a minimal decline in inventory over the two years. The Net Income figure is also overrated because the Accrued liabilities have almost doubled over the two years which puts the company at a delicate position if the creditors demand instant payment ((Epstein, 2014)). This position would not be the same in 2008 because the Cash from Operating Activities $177,387,000 was enough to cover the accrued liabiliti es of $41,079,000. Techno has also engaged in heavy borrowing both in short-term and Long-term in 2009 to probably support the business from the weak position confirmed by the declining ratio between a 73% rate in 2008 and it dropped to 8% in

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Delegating responsibilities is the key to effective management - Coursework Example Delegating work is truly a way to manage an organization successfully. Delegation is not meant to reduce the workload on the leader but to promote professionalism to other staff. Delegation when not well done can lead to other personnel seeing it as the abuse of power. It should be conducted in a manner that reflects it as a transfer of power and skill to another person. It also involves a process of selecting the right person to carry on, which also relies on the leader to be available for support and consultation, instead of supervision. (Jackson, 2015, p.189-190). Some leaders always think that delegating works is a way to relieve themselves from duty which should not be the case. They should guide those delegated, on how things should be done to achieve the set goals. Delegation needs a good mutual relationship between the two for it to be successful. Inadequate delegation can be like a rowing boat with only you doing the rowing. Your subordinate presence is just for the ride which leads too tiring and pressured management. (Burns, 2001, p.10). Creating a healthy environment with the subordinates is the key to delivering set goals. The relationship between a leader and junior staffs is vital in delegating task. For example, a leader who is too harsh to his subordinates may lead to the delegated task poorly performed while a leader who motivates his subordinate through rewards and promotions stand a high chance of achieving successful delegation. Delegation to be successful it must be conducted in a sequence of events that are: assignment of the task, delegation of authority, acceptance of responsibility assigned, and creation of accountability. Delegation does not relieve managers of Responsibility and accountability, that implies that managers will always be responsible and accountable for the task delegated, (Plunket & Warren, 2011, p.191-200). Developing efficient delegating strategies is the key success to productive management. When

EMR Implementation and Patient Flow Case Study Example | Topics and Well Written Essays - 500 words

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Age of Enlightenment Essay Example for Free

Age of Enlightenment Essay In his essay ‘What is Enlightenment?’ Immanuel Kant discusses the nature of Enlightenment and how it can be brought to the general public. According to Kant, â€Å"Enlightenment is man’s release from his self-incurred tutelage.† By this, Kant means that Enlightenment is when one man is able to make use of his understanding without guidance from another man. Kant sees an Age of Enlightenment as a time when the human society can be liberated from their nature of discharge, which is a need for someone to be their director. However, Kant also states that we have a natural need for tutelage when we are young, and that it is perfectly all right. In addition, after nature discharges us of this need, we should activate our rational ability. Enlightenment according to Kant is the progress of a society through free activity of rational thought and intellectual assessment. In an Enlightened Age, the public would be able to manage their given freedoms with competence. However, Kant claims that we do not live in an ‘Enlightened Age’; rather, we live in an ‘Age of Enlightenment.’ By this statement, he means that an Enlightened Age would be an age where we have overcome all self-incurred tutelage. An Age of Enlightenment is the current age, where we have not overcome all self-incurred tutelage, but where we have begun to activate our own powers of reason and have begun to make progress through critique. Also in his essay, Kant distinguishes between the public and private use of reason. He states that ‘the public use of one’s reason must always be free and it alone can bring about enlightenment among men.’ In saying this, the author views public usage of reason as for the purpose of progress. Kant regards the private use of reason as ‘that which one may make of it in a particular civil post or office which is entrusted to him.’ In other words, the philosopher explains the private use of reason as a rational worker in a specific occupation. In my opinion, Kant was a great thinker. I could not argue with his supporters that claim that he is the last philosopher. Reading this clip of his beliefs, I think that Kant makes a great point. I agree that for the human race to be considered enlightened we will need to avoid the natural urge to want to not feel alienated. Humans are generally a dependant species, needing company or some sort of contact with other humans. Along with this, we usually do not want to feel different and hence, we sometimes model our actions after what we see others do. In conclusion, Immanuel Kant’s essay, ‘What is Enlightenment?’ describes the time we are living in as an Age of Enlightenment, not an Enlightened Age. Kant also theorizes that to be in the ideal Enlightened Age, society will have to make irrational thoughts and actions obsolete. Society will need to make decisions after careful study of the possible outcome and effects their choices may cause. Bibliography: Essay what is enlightenment? by Immaneul kant

Combat Methamphetamine Epidemic Act of 2005 Essay Example for Free

Combat Methamphetamine Epidemic Act of 2005 Essay Methamphetamine commonly referred as meth or crystal has been a real and growing problem in the United States. Many of us don’t realize that meth is the most addictive drug worldwide. The main ingredients of meth, ephedrine and pseudoephedrine, are found in cold medicine. Relatively cheap and easy to get methamphetamine destructively affect your brain. It releases dopamine (the brain’s principal pleasure chemical) which boost up your energy, and as describe by many addicts in the movie:† it gives you a euphoric rush†¦and it’s a good feeling† (Woman in trailer). Meth can be obtained from household products, this dangerous process is called shake and bake since it consists of mixing ingredient that were never meant to be mix. The use of such drug affect your physical appearance and ruin your life whether on a personal or social level. The reason is after several hit the consummation of meth is the only activity that bring you joy out life. The effect are so devastative that an addict suggest that it should be wipe off the surface of earth. The methamphetamine epidemic started in Portland Oregon and its spreading to the West Coast of America. Surprisingly the people being affected by the drug are often college students, truck drivers and bikers. Researches have shown that it became an extended issue in the 1990’s. The meth epidemic represents a social issue because it is the leading cause in property crimes, children in foster care, sexual abuse, domestic violence and identity theft†¦. Effects of meth epidemic on social institutions The destructive effects of meth epidemic on family are undeniable. The harm caused by methamphetamine is so deep that an addict stated: â€Å"In all reality, I think they need to take a bomb and blow it all up†. It is painful to see the life and joy being eat out of a community. The story of Debbie Vick illustrates child endangerment. In fact children are sent to foster care in large number because of addicted parents unable to take care of their kids. High and under the effect of the stimulant, it is not uncommon for family members to be sexually abused by meth addicts. Unfortunately meth doesn’t only affect the users’ mental but it also significantly deteriorate their physical appearance. Deputy Bret King reported that a fairly appealing young woman, Theresa Baxter, looked 20 years older than she actually was and her teeth went missing. While methamphetamine only brings desolation among civilian what is being done to stop the spreading of this epidemic. The government has in some way aggravated the meth situation by its procedure. Although we can see that the police is very active at tracking down meth labs and meth addict more actions can and need to be taking toward resolving this issue. Quaalude showed us that if the proper measures are taken meth can be definitively eradicated. Initiatively a bill required for distributors of ephedrine and pseudoephedrine to verify the identities of their customers in order to control the consumers of those ingredients. The government ultimately finds opposition in the pharmaceutical industry because the bill was economically at their disadvantage. How can a sick soul find remedy if it cannot recognize that it needs treatment!!! It is the same for politics. As far as they are concerned meth is not an epidemic. Methamphetamine represented such low priority for them that no funds were going toward monitoring the key ingredients of meth shoppers. Dealing with heroin, cocaine or gangs was considerably more important although legislators in Oregon resurrected the idea that buyers of products with pseudoephedrine register at the store counter. Congress is completely aware that to terminate this problem they have to get to the roots which are companies providing key ingredients of meth. In order to address the issue Congress is considering the Combat Meth Act that will put pseudoephedrine under lock in store nationwide. However passing the Combat Meth Act promise to be more difficult than they thought. The cold medicine factories is estimated to be approximately a 3 billion money maker in the United States. Why would the pharmaceutical companies put their profit at risk by allowing the key ingredient of meth to be strictly regulated? In a market system where the rule of the game is to make money they will do anything necessary to stop any bill that will in some way affect negatively their industries. The fact that they made sure the bill was amended to exempt cold medicine clearly illustrates how they remain indifferent to the devastative effects of meth in the lives of so many Americans. Technology was at the base of detecting methamphetamine as a social issue. The advances in technology allowed us to explain the effects of meth in the human brain as it releases a huge amount dopamine. Researchers have shown that by putting the stimulant over and over in your brain it results in an inability to experience pleasure in your own, this is one of the main reasons addicts get back to using. What is the role of the media in this situation? Is he keeping us in the dark and not informing about what is happening? The Oregonians are well informed about meth sweeping across America and their own community. The media in Oregon Portland is doing a good job at exposing the issue to them. The impact of meth on the people of Oregon made the top actualities on Oregon new reported the narrator. Unfortunately I cannot say the same for the rest of the country. People being interviewed for example In D. C would often say:† Methamphetamine? I don’t know what it is (Rep. Brian Baird). While the epidemic was spreading politicians closed their eyes on the issue and population of affected states remained ignorant of the danger. The film depicts two faces of medicine regarding meth epidemic. On one side are the pharmaceutical companies that refuses to collaborate with the DEA toward finding a solution to the problem. We have seen that although the Meth Epidemic Act was put in place to control the purchase of the key ingredient in meth, pharmacist would compromised themselves and sell the ingredient in quantity. As the movie mentioned it the rule of the game is to make money and sell products. However we cannot overlook the good side of medicine. In Oregon innovative treatment programs helps the addicts trough the phase of detoxification. Certain centers often allow addicts to keep their child because they believe that the presence of a family member would motivate patients to get clean. Consider that most of the patients being treated for burns due to hazardous experiences in meth lab had no insurances it represented a deficit for the hospitals. Reflection I really enjoyed watching the Meth Epidemic film. In some way I feel like I am more informed and conscious about what is really going on in the world around me. In complete honesty I was not aware that such drug even existed. The movie clearly defined methamphetamine as far the most addictive drug in the United States and it is frightening to realize its destructive effects in the lives of countless families. Meth has become a personal concern when I learned that those being affected are mainly college students, truck drivers and athletes. As a student I cannot close my eyes on the fact that meth has been the cause of so many bright youth wasted in this decade. Meth is considered as a social and economic problem. This stimulant has accumulated over one and half millions addicts over the past years. The desolating part of it is that meth is so easy and cheap to get. In reality it has been show that most people will get the ingredient from their household products and cook it by the process commonly referred as â€Å"shake and bake†. Under the effect of such destructive drug, meth addicts turn violent and become unstable. The film discussed in depth the many issues that come along with this addiction. As far as family is concerned, meth is the leading cause for children in foster care and sexual abuse. However it doesn’t stop there property crimes and identity theft also represent other way for them to feed their addictions. I think the harm caused by the addicted parents can never be erased of the minds of those traumatized children. It is very likely for those meth orphans to lose themselves in the process. In my opinion the foster care system can’t really assure them the chance to a good future or a safe and loving home. In addition to that insecurity could be one of the consequence of property crimes or sexual abuse. This movie truly opened my eyes and the most shocking part was the insensitivity of the Pharmaceutical Companies. It is disturbing that money drives our actions and takes away any bit of humanity we could have left in ourselves!!! Pharmaceutical companies and politics play a very important role in this problem. Indeed the key ingredient for meth (ephedrine or pseudoephedrine) is found in cold medicine. While these companies are opposing to the strict regulation of these ingredients communities and families are suffering from the loved ones addicted to this drug. My personal experiences have thought me that people often resort to drugs when they are going through depression, stress or loneliness. Family support would help them look the other way and find reasonable solutions to their problem. Desperate diseases require desperate remedies. Thereupon the government should ensure that only customers with a prescription (signed by a certified physician) have access to medicine with ephedrine or pseudoephedrine. Meth can ruined someone’s life in a blink of an eye, a little inconvenience for people with cold is a small step to prevent meth epidemic. Meth also enters the country by the intermediary of drugs cartels in Mexico, The supervision at the border needs to be reinforced in order to stop their traditional smuggling. I believe that politic plays a crucial role in stopping the epidemic. However the politicians, as leaders, have to admit that meth is a major problem. Congress needs to cooperate with the DEA instead of making so difficult for them to their jobs. They should put back the regulation requiring a license to pseudoephedrine pills. They should fund the DEA in effort of tracking down meth dealers. It is clear that cold medicines bring a lot of profits for pharmaceutical companies. One of the argument presented by their spokesman is the availability of the ingredient for the American customer or the inconvenience for those with cold. I would suggest for them to research an alternative for ephedrine or pseudoephedrine. This way pharmaceuticals industries would still make money selling cold medicines, the DEA would have a peace of mind when it comes to dealing with meth and finally the American public would still have their cold reliever. People rely on the media for information about specific details of the happenings around them. The Oregonian newspaper set a good example of should be done. The media needs to insert the reality of meth in our daily lives so we can be aware of its danger. Meth epidemic need to make the headlines of our news nationwide for us to understand the urge to take action and stop the spread of the epidemic. Portland Oregon is not the only are area being affected by the meth epidemic. The statistics demonstrate that it is spreading to the east coast. More rehabilitation center is needed across the country to support the meth addicts. The pharmaceutical industries should collaborate with the DEA for the well-being of our society especially for the protection of our youth.

Underwater Acoustic Sensor Network (UASN)

Underwater Acoustic Sensor Network (UASN) CHAPTER1: Introduction Most of the earth surface is composed of water including fresh water from river, lakes etc and salt water from the sea. There are still many un-explored areas for such places. This needs significant research efforts and good communication systems. Wireless sensor network in aqueous medium has the ability to explore the underwater environment in details. For all applications of underwater, a good communication system as well as an effective routing protocol is needed. This will enable the underwater devices to communicate precisely. Underwater propagation speed varies with temperature, salinity and depth. By varying the underwater propagation speed at different depth, two scenarios can be achieved accurately namely: shallow and deep water. Shallow water consists of depth less than 200m and cylinder spreading. Deep water consists of depth greater or equal to 200 m and spherical spreading. In both shallow and deep water, different ambient noise and different spreading factor is applied. CHAPTER 2: Study of Underwater Acoustic Sensor Network (UASN) Application of UASN Wireless sensor network in aqueous medium also known as underwater sensor network has enabled a broad range of applications including: Environmental Monitoring Underwater sensor network can be used to monitor pollution like chemical, biological such as tracking of fish or micro-organisms, nuclear and oil leakage pollutions in bays, lakes or rivers [1]. Underwater sensor network can also be used to improve weather forecast, detect climate change, predict the effect of human activities on marine ecosystems, ocean currents and temperature change e.g. the global warming effect to ocean. Under Ocean Exploration Exploring minerals, oilfields or reservoir, determine routes for laying undersea cables and exploration valuable minerals can be done with such underwater sensor network. Disaster Prevention Sensor network that measure seismic activity from remote locations can provide tsunami warning to coastal areas, or study the effects of submarine earthquakes (seaquakes) [2] Equipment Monitoring Long-term equipment monitoring may be done with pre-installed infrastructure. Short-term equipment monitoring shares many requirements of long-term seismic monitoring, including the need for wireless (acoustic) communication, automatic configuration into a multihop network, localization (and hence time synchronization), and energy efficient operation Mine Reconnaissance By using acoustic sensors and optical sensors together, mine detection can be accomplished quickly and effectively. Assisted Monitoring Sensor can be used to discover danger on the seabed, locate dangerous rocks or shoals in shallow waters, mooring position, submerged wrecks and to perform bathymetry profiling. Information collection The main goal of communication network is the exchange of information inside the network and outside the network via a gateway or switch center. This application is used to share information among nodes and autonomous underwater vehicles. Characteristic of UASN Underwater Acoustic Networks (UANs), including but not limited to, Underwater Acoustic Sensor Networks (UASNs) and Autonomous Underwater Vehicle Networks (AUVNs) , are defined as networks composed of more than two nodes, using acoustic signals to communicate, for the purpose of underwater applications. UASNs and AUVNs are two important kinds of UANs. The former is composed of many sensor nodes, mostly for a monitoring purpose. The nodes are usually without or with limited capacity to move. The latter is composed of autonomous or unmanned vehicles with high mobility, deployed for applications that need mobility, e.g., exploration. An UAN can be an UASN, or an AUVN, or a combination of both. Acoustic communications, on the other hands, is defined as communication methods from one point to another by using acoustic signals. Network structure is not formed in acoustic point-to-point communications. Sound travels best through the water in comparison with electromagnetic waves and optical signals. Acoustic signal is sound signal waveform, usually produced by sonar for underwater applications. Acoustic signal processing extracts information from acoustic signals in the presence of noise and uncertainty. Underwater acoustic communications are mainly influenced by path loss, noise, multi-path, Doppler spread, and high and variable propagation delay. All these factors determine the temporal and spatial variability of the acoustic channel, and make the available bandwidth of the Underwater Acoustic channel (UW-A) limited and dramatically dependent on both range and frequency. Long-range systems that operate over several tens of kilometers may have a bandwidth of only a few kHz, while a short-range system operating over several tens of meters may have more than a hundred kHz bandwidth. These factors lead to low bit rate. Underwater acoustic communication links can be classified according to their range as very long, long, medium, short, and very short links. Acoustic links are also roughly classified as vertical and horizontal, according to the direction of the sound ray. Their propagation characteristics differ consistently, especially with respect to time dispersion, multi-path spreads, and delay variance. Acoustic signal is the only physical feasible tool that works in underwater environment. Compared with it, electromagnetic wave can only travel in water with short distance due to the high attenuation and absorption effect in underwater environment. It is found that the absorption of electromagnetic energy in sea water is about 45Ãâ€" ?f dB per kilometer, where f is frequency in Hertz; In contrast, the absorption of acoustic signal over most frequencies of interest is about three orders of magnitude lower [40]. Hereafter the factors that influence acoustic communications is analyzed in order to state the challenges posed by the underwater channels for underwater sensor networking. These include: Path loss Attenuation is mainly provoked by absorption due to conversion of acoustic energy into heat, which increases with distance and frequency. It is also caused by scattering a reverberation (on rough ocean surface and bottom), refraction, and dispersion (due to the displacement of the reflection point caused by wind on the surface). Water depth plays a key role in determining the attenuation. Geometric Spreading is the spreading of sound energy as a result of the expansion of the wavefronts. It increases with the propagation distance and is independent of frequency. There are two common kinds of geometric spreading: spherical (omni-directional point source), and cylindrical (horizontal radiation only). Noise Man made noise is mainly caused by machinery noise (pumps, reduction gears, power plants, etc.), and shipping activity (hull fouling, animal life on hull, cavitations), especially in areas encumbered with heavy vessel traffic. Ambient Noise is related to hydrodynamics (movement of water including tides, current, storms, wind, rain, etc.), seismic and biological phenomena. Multi-path Multi-path propagation may be responsible for severe degradation of the acoustic communication signal, since it generates Inter-Symbol Interference (ISI). The multi-path geometry depends on the link configuration. Vertical channels are characterized by little time dispersion, whereas horizontal channels may have extremely long multi-path spreads. The extent of the spreading is a strong function of depth and the distance between transmitter and receiver. High delay and delay variance The propagation speed in the UW-A channel is five orders of magnitude lower than in the radio channel. This large propagation delay (0.67 s/km) can reduce the throughput of the system considerably. The very high delay variance is even more harmful for efficient protocol design, as it prevents from accurately estimating the round trip time (RTT), which is the key parameter for many common communication protocols. Doppler spread The Doppler frequency spread can be significant in UW-A channels, causing degradation in the performance of digital communications: transmissions at a high data rate because many adjacent symbols to interfere at the receiver, requiring sophisticated signal processing to deal with the generated ISI. The Doppler spreading generates: a simple frequency translation, which is relatively easy for a receiver to compensate for a continuous spreading of frequencies, which constitutes a non-shifted signal, which is more difficult for a receiver to compensate for. If a channel has a Doppler spread with bandwidth B and a signal has symbol duration T, then there are approximately BT uncorrelated samples of its complex envelope. When BT is much less than unity, the channel is said to be under spread and the effects of the Doppler fading can be ignored, while, if greater than unity, it is overspread. Most of the described factors are caused by the chemical-physical properties of the water medium such as temperature, salinity and density, and by their spatio-temporal variations. These variations, together with the wave guide nature of the channel, because the acoustic channel to be temporally and spatially variable. In particular, the horizontal channel is by far more rapidly varying than the vertical channel, in both deep and shallow water. CHAPTER 3: Network Architecture Underwater sensor nodes: The underwater sensor nodes are deployed on the sea floor anchored to the ocean bottom [32]. The sensors are equipped with floating buoys to push the nodes upwards, thus they are relatively stationary nodes [3]. Using acoustic links, they relay data to underwater sink directly or via multi-hop path. Underwater sink nodes: Underwater sink nodes take charge of collecting data of underwater sensors deployed on the ocean bottom and then send to the surface sink node. They may be equipped with vertical and horizontal acoustic transducers. The horizontal transceiver is used to collect the sensors data and the vertical transceiver provides transmitting link between underwater sink and the surface sink node. Surface sink node: Surface sink node is attached on a floating buoy with satellite, radio frequency (RF) or cell phone technology to transmit data to shore in real time. 2D Model A reference architecture for two-dimensional underwater networks is shown in Figure. 1. A group of sensor nodes are anchored to the deep of the ocean. Underwater sensor nodes are interconnected to one or more underwater gateways by means of wireless acoustic links. Underwater-gateways are network devices in charge of relaying data from the ocean bottom network to a surface station. To achieve this objective, they are equipped with two acoustic transceivers, namely a vertical and a horizontal transceiver. The horizontal transceiver is used by the underwater-gateway to communicate with the sensor nodes in order to: send commands and configuration data to the sensors (underwater -gateway to sensors); collect monitored data (sensors to underwater -gateway). The vertical link is used by the underwater -gateways to relay data to a surface station. In deep water applications, vertical transceivers must be long range transceivers. The surface station is equipped with an acoustic transceiver that is able to handle multiple parallel communications with the deployed underwater -gateways. It is also endowed with a long range RF and/or satellite transmitter to communicate with the onshore sink (os-sink) and/or to a surface sink (s-sink). In shallow water, bottom-deployed sensors/modems may directly communicate with the surface buoy, with no specialized bottom node (underwater -gateway). 3D Model Three-dimensional underwater networks are used to detect and observe phenomena that cannot be adequately observed by means of ocean bottom sensor nodes, i.e., to perform cooperative sampling of the 3D ocean environment. In three-dimensional underwater networks, sensor nodes float at different depths to observe a phenomenon. In this architecture, given in Figure 2, each sensor is anchored to the ocean bottom and equipped with a floating buoy that can be inflated by a pump. The buoy pushes the sensor towards the ocean surface. The depth of the sensor can then be regulated by adjusting the length of the wire that connects the sensor to the anchor, by means of an electronically controlled engine that resides on the sensor. Sensing and communication coverage in a 3D environment are rigorously investigated in [8]. The diameter, minimum and maximum degree of the reachability graph that describes the network are derived as a function of the communication range, while different degrees of cov erage for the 3D environment are characterized as a function of the sensing range. 3D Model with AUV The above figure represents the third type of network architecture which consist of sensor nodes and Autonomous Underwater Vehicles (AUV) which act as mobile sensor nodes for ocean monitoring, underwater resource study, etc. CHAPTER 4: Differences between underwater and terrestrial Sensor Network An underwater acoustic channel is different from a ground-based radio channel from many aspects, including: Bandwidth is extremely limited. The attenuation of acoustic signal increases with frequency and range [6] [10]. Consequently, the feasible band is extremely small. For example, a short range system operating over several tens of meters may have available bandwidth of a hundred kHz; a medium-range system operating over several kilometers has a bandwidth on the order of ten kHz; and a long-range system operating over several tens of kilometers is limited to only a few kHz of bandwidth [11]. Propagation delay is long. The transmission speed of acoustic signals in salty water is around 1500 meter/s [22], which is a difference of five orders of magnitude lower than the speed of electromagnetic wave in free space. Correspondently, propagation delay in an underwater channel becomes significant. This is one of the essential characteristics of underwater channels and has profound implications on localization and time synchronization. The channel impulse response is not only spatially varied but also temporarily varied. The channel characteristics vary with time and highly depend on the location of the transmitter and receiver. The fluctuation nature of the channel causes the received signals easily distorted. There are two types of propagation paths: macro-multipaths, which are the deterministic propagation paths; and micro-multipath, which is a random signal fluctuation. The macro-multipaths are caused by both reflection at the boundaries (bottom, surface and any object in the water) and bending. Inter- Symbol Interference (ISI) thus occurs. Compared with the spread of its ground-based counterpart, which is on the order of several symbol intervals, ISI spreading in an underwater acoustic channel is several tens or hundred of symbol intervals for moderate to high data rate in the horizontal channel. Micro-multipath fluctuations are mainly caused by surface wave, which contributes the most to the time variability of shallow water channel. In deep water, internal waves impact the single-path random fluctuations [12][13]. Probability of bit error is much higher and temporary loss of connectivity (shadow zone) sometimes occurs, due to the extreme characteristics of the channel. Cost. While terrestrial sensor nodes are expected to become increasingly inexpensive, underwater sensors are expensive devices. This is especially due to the more complex underwater transceivers and to the hardware protection needed in the extreme underwater environment. Also, because of the low economy of scale caused by a small relative number of suppliers, underwater sensors are characterized by high cost. Deployment. While terrestrial sensor networks are densely deployed, in underwater, the deployment is generally more sparse. Power. The power needed for acoustic underwater communications is higher than in terrestrial radio communications because of the different physical layer technology (acoustic vs. RF waves), the higher distances, and more complex signal processing techniques implemented at the receivers to compensate for the impairments of the channel. Memory. While terrestrial sensor nodes have very limited storage capacity, underwater-sensors may need to be able to do some data caching as the underwater channel may be intermittent. Spatial Correlation. While the readings from terrestrial sensors are often correlated, this is more unlikely to happen in underwater networks due to the higher distance among sensors. CHAPTER 5: Layered of UASN The underwater architecture network consists of five layers, application, transport, network, data link and physical layer as shown in the figure below. As typical underwater systems have limited processing capability, the protocol has been kept as simple as possible without significantly compromising performance. The underwater sensor network specifications currently do not include any recommendations for authentication and encryption. These may be easily implemented at the application layer or via a spreading scheme at the physical layer. Each layer is described by a SAPI. The SAPI is defined in terms of messages being passed to and from the layer. The clients (usually higher layers) of a layer invoke the layer via a request (REQ). The layer responds to each REQ by a response (RSP). Errors are reported via an ERR RSP with error codes. If the layer needs to send unsolicited messages to the client, it does so via a notification (NTF). A layer communicates logically with its peer layer via protocol data units (PDU). As the peer-to-peer communication is symmetric, a layer may send a REQ PDU to its peer layer at any time. It would optionally respond to such a PDU with a RSP PDU. This is logically depicted in Figure below It may be desirable in some cases, that non-neighboring layers communicate with each other to achieve cross-layer optimization. This may be implemented by allowing REQ and RSP PDUs between any two layers in the protocol stack. The underwater sensor network specifications define detailed message structures for all SAPI messages. These message structures include message identifiers, data formats to be used, parameters and their possible values Physical layer The physical layer provides framing, modulation and error correction capability (via FEC). It provides primitives for sending and receiving packets. It may also provide additional functionality such as parameter settings, parameter recommendation, carrier sensing, etc. At first underwater channel development was based on non-coherent frequency shift keying (FSK) modulation, since it relies on energy detection. Thus, it does not require phase tracking, which is a very difficult task mainly because of the Doppler-spread in the underwater acoustic channel. Although non-coherent modulation schemes are characterized by high power efficiency, their low bandwidth efficiency makes them unsuitable for high data rate multiuser networks. Hence, coherent modulation techniques have been developed for long-range, high-throughput systems. In the last years, fully coherent modulation techniques, such as phase shift keying (PSK) and quadrature amplitude modulation (QAM), have become practical due to the availability of powerful digital processing. Channel equalization techniques are exploited to leverage the effect of the inter-symbol interference (ISI), instead of trying to avoid or suppress it. Decision-feedback equalizers (DFEs) track the complex, relatively slowly varying channel response and thus provide high throughput when the channel is slowly varying. Conversely, when the channel varies faster, it is necessary to combine the DFE with a Phase Locked Loop (PLL) [9], which estimates and compensates for the phase offset in a rapid, stable manner. The use of decision feedback equalization and phase-locked loops is driven by the complexity and time variability of ocean channel impulse responses. Differential phase shift keying (DPSK) serves as an intermediate solution between incoherent and fully coherent systems in terms of bandwidth efficiency. DPSK encodes information relative to the previous symbol rather than to an arbitrary fixed reference in the signal phase and may be referred to as a partially coherent modulation. While this strategy substantially alleviates carrier phase-tracking requirements, the penalty is an increased error probability over PSK at an equivalent data rate. Another promising solution for underwater communications is the orthogonal frequency division multiplexing (OFDM) spread spectrum technique, which is particularly efficient when noise is spread over a large portion of the available bandwidth. OFDM is frequently referred to as multicarrier modulation because it transmits signals over multiple sub-carriers simultaneously. In particular, sub-carriers that experience higher SNR, are allotted with a higher number of bits, whereas less bits are allotted to sub-carriers experiencing attenuation, according to the concept of bit loading, which requires channel estimation. Since the symbol duration for each individual carrier increases, OFDM systems perform robustly in severe multi-path environments, and achieve a high spectral efficiency. Many of the techniques discussed above require underwater channel estimation, which can be achieved by means of probe packets [17]. An accurate estimate of the channel can be obtained with a high probing rate and/or with a large probe packet size, which however result in high overhead, and in the consequent drain of channel capacity and energy. Data link layer (MAC layer) The data link layer provides single hop data transmission capability; it will not be able to transmit a packet successfully if the destination node is not directly accessible from the source node. It may include some degree of reliability. It may also provide error detection capability (e.g. CRC check). In case of a shared medium, the data link layer must include the medium access control (MAC) sub-layer. Frequency division multiple access (FDMA) is not suitable for underwater sensor network due to the narrow bandwidth in underwater acoustic channels and the vulnerability of limited band systems to fading and multipath. Time division multiple access (TDMA) shows limited bandwidth efficiency because of the long time guards required in the underwater acoustic channel. In fact, long time guards must be designed to account for the large propagation delay and delay variance of the underwater channel in order to minimize packet collisions from adjacent time slots. Moreover, the variable delay makes it very challenging to realize a precise synchronization, with a common timing reference, which is required for TDMA. Carrier sense multiple access (CSMA) prevents collisions with the ongoing transmission at the transmitter side. To prevent collisions at the receiver side, however, it is necessary to add a guard time between transmissions dimensioned according to the maximum propagation delay in the network. This makes the protocol dramatically inefficient for underwater acoustic sensor network. The use of contention-based techniques that rely on handshaking mechanisms such as RTS/ CTS in shared medium access is impractical in underwater, for the following reasons: large delays in the propagation of RTS/CTS control packets lead to low throughput; due to the high propagation delay of underwater acoustic channels, when carrier sense is used, as in 802.11, it is more likely that the channel be sensed idle while a transmission is ongoing, since the signal may not have reached the receiver yet; the high variability of delay in handshaking packets makes it impractical to predict the start and finish time of the transmissions of other stations. Thus, collisions are highly likely to occur. Code division multiple access (CDMA) is quite robust to frequency selective fading caused by underwater multi-paths, since it distinguishes simultaneous signals transmitted by multiple devices by means of pseudo-noise codes that are used for spreading the user signal over the entire available band. CDMA allows reducing the number of packet retransmissions, which results in decreased battery consumption and increased network throughput. In conclusion, although the high delay spread which characterizes the horizontal link in underwater channels makes it difficult to maintain synchronization among the stations, especially when orthogonal code techniques are used [17], CDMA is a promising multiple access technique for underwater acoustic networks. This is particularly true in shallow water, where multi-paths and Doppler- spreading plays a key role in the communication performance. Network layer (Routing) The network layer is in charge of determining the path between a source (the sensor that samples a physical phenomenon) and a destination node (usually the surface station). In general, while many impairments of the underwater acoustic channel are adequately addressed at the physical and data link layers, some other characteristics, such as the extremely long propagation delays, are better addressed at the network layer. Basically, there are two methods of routing. The first one is virtual circuit routing and the second one is packet-switch routing. In virtual circuit routing, the networks use virtual circuits to decide on the path at the beginning of the network operation. Virtual-circuit-switch routing protocols can be a better choice for underwater acoustic networks. The reasons are: Underwater acoustic networks are typical asymmetric instead of symmetric. However, packet switched routing protocols are proposed for symmetric network architecture; Virtual-circuit-switch routing protocols work robust against link failure, which is critical in underwater environment; and Virtual-circuit-switch routing protocols have less signal overhead and low latency, which are needed for underwater acoustic channel environment. However, virtual-circuit-switch routing protocols usually lack of flexibility. In packet-switch routing, every node that is part of the transmission makes its own routing decision, i.e., decides its next hop to relay the packet. Packet-switch routing can be further classified into Proactive routing, Reactive and geographical routing protocols. Most routing protocols for ground-based wireless networks are packet-switch based. Proactive routing protocols attempt to minimize the message latency by maintaining up-to-date routing information at all times from each node to any other node. It broadcasts control packets that contain routing table information. Typical protocols include Destination Sequence Distance Vector (DSDV) [28] and Temporally Ordered Routing Algorithm (TORA). However, proactive routing protocols provoke a large signaling overhead to establish routes for the first time and each time the network topology changes. It may not be a good fit in underwater environment due to the high probability of link failure and extremely limited bandwidth there. Reactive routing protocols only initiate a route discovery process upon request. Correspondently, each node does not need to maintain a sizable look-up table for routing. This kind of routing protocols is more suitable for dynamic environment like ad hoc wireless networks. Typical protocol examples are Ad hoc On-demand Distance Vector (AODV) [23], and Dynamic Source Routing (DSR) [27]. The shortage of reactive routing protocols is its high latency to establish routing. Similar to its proactive counterpart, flooding of control packets to establish paths is needed, which brings significant signal overhead. The high latency could become much deteriorated in underwater environment because of the much slower propagation speed of acoustic signal compared with the radio wave in the air. Geographic routing (also called georouting or position-based routing) is a routing principle that relies on geographic position information. It is mainly proposed for wireless networks and based on the idea that the source sends a message to the geographic location of the destination instead of using the network address. Geographic routing requires that each node can determine its own location and that the source is aware of the location of the destination. With this information a message can be routed to the destination without knowledge of the network topology or a prior route discovery. Transport layer A transport layer protocol is needed in underwater sensor network not only to achieve reliable collective transport of event features, but also to perform flow control and congestion control. The primary objective is to save scarce sensor resources and increase the network efficiency. A reliable transport protocol should guarantee that the applications be able to correctly identify event features estimated by the sensor network. Congestion control is needed to prevent the network from being congested by excessive data with respect to the network capacity, while flow control is needed to avoid that network devices with limited memory are overwhelmed by data transmissions. Most existing TCP implementations are unsuited for the underwater environment, since the flow control functionality is based on a window- based mechanism that relies on an accurate esteem of the round trip time (RTT), which is twice the end-to-end delay from source to destination. Rate-based transport protocols seem also unsuited for this challenging environment. They still rely on feedback control messages sent back by the destination to dynamically adapt the transmission rate, i.e., to decrease the transmission rate when packet loss is experienced or to increase it otherwise. The high delay and delay variance can thus cause instability in the feedback control. Furthermore, due to the unreliability of the acoustic channel, it is necessary to distinguish between packet losses due to the high bit error rate of the acoustic channel, from those caused by packets being dropped from the queues of sensor nodes due to network congestion. In terrestrial, assume that congestion is the only cause for packet loss and the solution lies on decreasing the transmission rate, but in underwater sensor network if the packet loss is due to bad channel then the transmission rate should not be decreased to preserve throughput efficiency. Transport layer functionalities can be tightly integrated with data link layer functionalities in a cross-layer module. The purpose of such an integrated module is to make the information about the condition of the variable underwater channel available also at the transport layer. In fact, usually the state of the channel is known only at the physical and channel access sub-layers, while the design principle of layer separation makes this information transparent to the higher layers. This integration allows maximizing the Underwater Acoustic Sensor Network (UASN) Underwater Acoustic Sensor Network (UASN) CHAPTER1: Introduction Most of the earth surface is composed of water including fresh water from river, lakes etc and salt water from the sea. There are still many un-explored areas for such places. This needs significant research efforts and good communication systems. Wireless sensor network in aqueous medium has the ability to explore the underwater environment in details. For all applications of underwater, a good communication system as well as an effective routing protocol is needed. This will enable the underwater devices to communicate precisely. Underwater propagation speed varies with temperature, salinity and depth. By varying the underwater propagation speed at different depth, two scenarios can be achieved accurately namely: shallow and deep water. Shallow water consists of depth less than 200m and cylinder spreading. Deep water consists of depth greater or equal to 200 m and spherical spreading. In both shallow and deep water, different ambient noise and different spreading factor is applied. CHAPTER 2: Study of Underwater Acoustic Sensor Network (UASN) Application of UASN Wireless sensor network in aqueous medium also known as underwater sensor network has enabled a broad range of applications including: Environmental Monitoring Underwater sensor network can be used to monitor pollution like chemical, biological such as tracking of fish or micro-organisms, nuclear and oil leakage pollutions in bays, lakes or rivers [1]. Underwater sensor network can also be used to improve weather forecast, detect climate change, predict the effect of human activities on marine ecosystems, ocean currents and temperature change e.g. the global warming effect to ocean. Under Ocean Exploration Exploring minerals, oilfields or reservoir, determine routes for laying undersea cables and exploration valuable minerals can be done with such underwater sensor network. Disaster Prevention Sensor network that measure seismic activity from remote locations can provide tsunami warning to coastal areas, or study the effects of submarine earthquakes (seaquakes) [2] Equipment Monitoring Long-term equipment monitoring may be done with pre-installed infrastructure. Short-term equipment monitoring shares many requirements of long-term seismic monitoring, including the need for wireless (acoustic) communication, automatic configuration into a multihop network, localization (and hence time synchronization), and energy efficient operation Mine Reconnaissance By using acoustic sensors and optical sensors together, mine detection can be accomplished quickly and effectively. Assisted Monitoring Sensor can be used to discover danger on the seabed, locate dangerous rocks or shoals in shallow waters, mooring position, submerged wrecks and to perform bathymetry profiling. Information collection The main goal of communication network is the exchange of information inside the network and outside the network via a gateway or switch center. This application is used to share information among nodes and autonomous underwater vehicles. Characteristic of UASN Underwater Acoustic Networks (UANs), including but not limited to, Underwater Acoustic Sensor Networks (UASNs) and Autonomous Underwater Vehicle Networks (AUVNs) , are defined as networks composed of more than two nodes, using acoustic signals to communicate, for the purpose of underwater applications. UASNs and AUVNs are two important kinds of UANs. The former is composed of many sensor nodes, mostly for a monitoring purpose. The nodes are usually without or with limited capacity to move. The latter is composed of autonomous or unmanned vehicles with high mobility, deployed for applications that need mobility, e.g., exploration. An UAN can be an UASN, or an AUVN, or a combination of both. Acoustic communications, on the other hands, is defined as communication methods from one point to another by using acoustic signals. Network structure is not formed in acoustic point-to-point communications. Sound travels best through the water in comparison with electromagnetic waves and optical signals. Acoustic signal is sound signal waveform, usually produced by sonar for underwater applications. Acoustic signal processing extracts information from acoustic signals in the presence of noise and uncertainty. Underwater acoustic communications are mainly influenced by path loss, noise, multi-path, Doppler spread, and high and variable propagation delay. All these factors determine the temporal and spatial variability of the acoustic channel, and make the available bandwidth of the Underwater Acoustic channel (UW-A) limited and dramatically dependent on both range and frequency. Long-range systems that operate over several tens of kilometers may have a bandwidth of only a few kHz, while a short-range system operating over several tens of meters may have more than a hundred kHz bandwidth. These factors lead to low bit rate. Underwater acoustic communication links can be classified according to their range as very long, long, medium, short, and very short links. Acoustic links are also roughly classified as vertical and horizontal, according to the direction of the sound ray. Their propagation characteristics differ consistently, especially with respect to time dispersion, multi-path spreads, and delay variance. Acoustic signal is the only physical feasible tool that works in underwater environment. Compared with it, electromagnetic wave can only travel in water with short distance due to the high attenuation and absorption effect in underwater environment. It is found that the absorption of electromagnetic energy in sea water is about 45Ãâ€" ?f dB per kilometer, where f is frequency in Hertz; In contrast, the absorption of acoustic signal over most frequencies of interest is about three orders of magnitude lower [40]. Hereafter the factors that influence acoustic communications is analyzed in order to state the challenges posed by the underwater channels for underwater sensor networking. These include: Path loss Attenuation is mainly provoked by absorption due to conversion of acoustic energy into heat, which increases with distance and frequency. It is also caused by scattering a reverberation (on rough ocean surface and bottom), refraction, and dispersion (due to the displacement of the reflection point caused by wind on the surface). Water depth plays a key role in determining the attenuation. Geometric Spreading is the spreading of sound energy as a result of the expansion of the wavefronts. It increases with the propagation distance and is independent of frequency. There are two common kinds of geometric spreading: spherical (omni-directional point source), and cylindrical (horizontal radiation only). Noise Man made noise is mainly caused by machinery noise (pumps, reduction gears, power plants, etc.), and shipping activity (hull fouling, animal life on hull, cavitations), especially in areas encumbered with heavy vessel traffic. Ambient Noise is related to hydrodynamics (movement of water including tides, current, storms, wind, rain, etc.), seismic and biological phenomena. Multi-path Multi-path propagation may be responsible for severe degradation of the acoustic communication signal, since it generates Inter-Symbol Interference (ISI). The multi-path geometry depends on the link configuration. Vertical channels are characterized by little time dispersion, whereas horizontal channels may have extremely long multi-path spreads. The extent of the spreading is a strong function of depth and the distance between transmitter and receiver. High delay and delay variance The propagation speed in the UW-A channel is five orders of magnitude lower than in the radio channel. This large propagation delay (0.67 s/km) can reduce the throughput of the system considerably. The very high delay variance is even more harmful for efficient protocol design, as it prevents from accurately estimating the round trip time (RTT), which is the key parameter for many common communication protocols. Doppler spread The Doppler frequency spread can be significant in UW-A channels, causing degradation in the performance of digital communications: transmissions at a high data rate because many adjacent symbols to interfere at the receiver, requiring sophisticated signal processing to deal with the generated ISI. The Doppler spreading generates: a simple frequency translation, which is relatively easy for a receiver to compensate for a continuous spreading of frequencies, which constitutes a non-shifted signal, which is more difficult for a receiver to compensate for. If a channel has a Doppler spread with bandwidth B and a signal has symbol duration T, then there are approximately BT uncorrelated samples of its complex envelope. When BT is much less than unity, the channel is said to be under spread and the effects of the Doppler fading can be ignored, while, if greater than unity, it is overspread. Most of the described factors are caused by the chemical-physical properties of the water medium such as temperature, salinity and density, and by their spatio-temporal variations. These variations, together with the wave guide nature of the channel, because the acoustic channel to be temporally and spatially variable. In particular, the horizontal channel is by far more rapidly varying than the vertical channel, in both deep and shallow water. CHAPTER 3: Network Architecture Underwater sensor nodes: The underwater sensor nodes are deployed on the sea floor anchored to the ocean bottom [32]. The sensors are equipped with floating buoys to push the nodes upwards, thus they are relatively stationary nodes [3]. Using acoustic links, they relay data to underwater sink directly or via multi-hop path. Underwater sink nodes: Underwater sink nodes take charge of collecting data of underwater sensors deployed on the ocean bottom and then send to the surface sink node. They may be equipped with vertical and horizontal acoustic transducers. The horizontal transceiver is used to collect the sensors data and the vertical transceiver provides transmitting link between underwater sink and the surface sink node. Surface sink node: Surface sink node is attached on a floating buoy with satellite, radio frequency (RF) or cell phone technology to transmit data to shore in real time. 2D Model A reference architecture for two-dimensional underwater networks is shown in Figure. 1. A group of sensor nodes are anchored to the deep of the ocean. Underwater sensor nodes are interconnected to one or more underwater gateways by means of wireless acoustic links. Underwater-gateways are network devices in charge of relaying data from the ocean bottom network to a surface station. To achieve this objective, they are equipped with two acoustic transceivers, namely a vertical and a horizontal transceiver. The horizontal transceiver is used by the underwater-gateway to communicate with the sensor nodes in order to: send commands and configuration data to the sensors (underwater -gateway to sensors); collect monitored data (sensors to underwater -gateway). The vertical link is used by the underwater -gateways to relay data to a surface station. In deep water applications, vertical transceivers must be long range transceivers. The surface station is equipped with an acoustic transceiver that is able to handle multiple parallel communications with the deployed underwater -gateways. It is also endowed with a long range RF and/or satellite transmitter to communicate with the onshore sink (os-sink) and/or to a surface sink (s-sink). In shallow water, bottom-deployed sensors/modems may directly communicate with the surface buoy, with no specialized bottom node (underwater -gateway). 3D Model Three-dimensional underwater networks are used to detect and observe phenomena that cannot be adequately observed by means of ocean bottom sensor nodes, i.e., to perform cooperative sampling of the 3D ocean environment. In three-dimensional underwater networks, sensor nodes float at different depths to observe a phenomenon. In this architecture, given in Figure 2, each sensor is anchored to the ocean bottom and equipped with a floating buoy that can be inflated by a pump. The buoy pushes the sensor towards the ocean surface. The depth of the sensor can then be regulated by adjusting the length of the wire that connects the sensor to the anchor, by means of an electronically controlled engine that resides on the sensor. Sensing and communication coverage in a 3D environment are rigorously investigated in [8]. The diameter, minimum and maximum degree of the reachability graph that describes the network are derived as a function of the communication range, while different degrees of cov erage for the 3D environment are characterized as a function of the sensing range. 3D Model with AUV The above figure represents the third type of network architecture which consist of sensor nodes and Autonomous Underwater Vehicles (AUV) which act as mobile sensor nodes for ocean monitoring, underwater resource study, etc. CHAPTER 4: Differences between underwater and terrestrial Sensor Network An underwater acoustic channel is different from a ground-based radio channel from many aspects, including: Bandwidth is extremely limited. The attenuation of acoustic signal increases with frequency and range [6] [10]. Consequently, the feasible band is extremely small. For example, a short range system operating over several tens of meters may have available bandwidth of a hundred kHz; a medium-range system operating over several kilometers has a bandwidth on the order of ten kHz; and a long-range system operating over several tens of kilometers is limited to only a few kHz of bandwidth [11]. Propagation delay is long. The transmission speed of acoustic signals in salty water is around 1500 meter/s [22], which is a difference of five orders of magnitude lower than the speed of electromagnetic wave in free space. Correspondently, propagation delay in an underwater channel becomes significant. This is one of the essential characteristics of underwater channels and has profound implications on localization and time synchronization. The channel impulse response is not only spatially varied but also temporarily varied. The channel characteristics vary with time and highly depend on the location of the transmitter and receiver. The fluctuation nature of the channel causes the received signals easily distorted. There are two types of propagation paths: macro-multipaths, which are the deterministic propagation paths; and micro-multipath, which is a random signal fluctuation. The macro-multipaths are caused by both reflection at the boundaries (bottom, surface and any object in the water) and bending. Inter- Symbol Interference (ISI) thus occurs. Compared with the spread of its ground-based counterpart, which is on the order of several symbol intervals, ISI spreading in an underwater acoustic channel is several tens or hundred of symbol intervals for moderate to high data rate in the horizontal channel. Micro-multipath fluctuations are mainly caused by surface wave, which contributes the most to the time variability of shallow water channel. In deep water, internal waves impact the single-path random fluctuations [12][13]. Probability of bit error is much higher and temporary loss of connectivity (shadow zone) sometimes occurs, due to the extreme characteristics of the channel. Cost. While terrestrial sensor nodes are expected to become increasingly inexpensive, underwater sensors are expensive devices. This is especially due to the more complex underwater transceivers and to the hardware protection needed in the extreme underwater environment. Also, because of the low economy of scale caused by a small relative number of suppliers, underwater sensors are characterized by high cost. Deployment. While terrestrial sensor networks are densely deployed, in underwater, the deployment is generally more sparse. Power. The power needed for acoustic underwater communications is higher than in terrestrial radio communications because of the different physical layer technology (acoustic vs. RF waves), the higher distances, and more complex signal processing techniques implemented at the receivers to compensate for the impairments of the channel. Memory. While terrestrial sensor nodes have very limited storage capacity, underwater-sensors may need to be able to do some data caching as the underwater channel may be intermittent. Spatial Correlation. While the readings from terrestrial sensors are often correlated, this is more unlikely to happen in underwater networks due to the higher distance among sensors. CHAPTER 5: Layered of UASN The underwater architecture network consists of five layers, application, transport, network, data link and physical layer as shown in the figure below. As typical underwater systems have limited processing capability, the protocol has been kept as simple as possible without significantly compromising performance. The underwater sensor network specifications currently do not include any recommendations for authentication and encryption. These may be easily implemented at the application layer or via a spreading scheme at the physical layer. Each layer is described by a SAPI. The SAPI is defined in terms of messages being passed to and from the layer. The clients (usually higher layers) of a layer invoke the layer via a request (REQ). The layer responds to each REQ by a response (RSP). Errors are reported via an ERR RSP with error codes. If the layer needs to send unsolicited messages to the client, it does so via a notification (NTF). A layer communicates logically with its peer layer via protocol data units (PDU). As the peer-to-peer communication is symmetric, a layer may send a REQ PDU to its peer layer at any time. It would optionally respond to such a PDU with a RSP PDU. This is logically depicted in Figure below It may be desirable in some cases, that non-neighboring layers communicate with each other to achieve cross-layer optimization. This may be implemented by allowing REQ and RSP PDUs between any two layers in the protocol stack. The underwater sensor network specifications define detailed message structures for all SAPI messages. These message structures include message identifiers, data formats to be used, parameters and their possible values Physical layer The physical layer provides framing, modulation and error correction capability (via FEC). It provides primitives for sending and receiving packets. It may also provide additional functionality such as parameter settings, parameter recommendation, carrier sensing, etc. At first underwater channel development was based on non-coherent frequency shift keying (FSK) modulation, since it relies on energy detection. Thus, it does not require phase tracking, which is a very difficult task mainly because of the Doppler-spread in the underwater acoustic channel. Although non-coherent modulation schemes are characterized by high power efficiency, their low bandwidth efficiency makes them unsuitable for high data rate multiuser networks. Hence, coherent modulation techniques have been developed for long-range, high-throughput systems. In the last years, fully coherent modulation techniques, such as phase shift keying (PSK) and quadrature amplitude modulation (QAM), have become practical due to the availability of powerful digital processing. Channel equalization techniques are exploited to leverage the effect of the inter-symbol interference (ISI), instead of trying to avoid or suppress it. Decision-feedback equalizers (DFEs) track the complex, relatively slowly varying channel response and thus provide high throughput when the channel is slowly varying. Conversely, when the channel varies faster, it is necessary to combine the DFE with a Phase Locked Loop (PLL) [9], which estimates and compensates for the phase offset in a rapid, stable manner. The use of decision feedback equalization and phase-locked loops is driven by the complexity and time variability of ocean channel impulse responses. Differential phase shift keying (DPSK) serves as an intermediate solution between incoherent and fully coherent systems in terms of bandwidth efficiency. DPSK encodes information relative to the previous symbol rather than to an arbitrary fixed reference in the signal phase and may be referred to as a partially coherent modulation. While this strategy substantially alleviates carrier phase-tracking requirements, the penalty is an increased error probability over PSK at an equivalent data rate. Another promising solution for underwater communications is the orthogonal frequency division multiplexing (OFDM) spread spectrum technique, which is particularly efficient when noise is spread over a large portion of the available bandwidth. OFDM is frequently referred to as multicarrier modulation because it transmits signals over multiple sub-carriers simultaneously. In particular, sub-carriers that experience higher SNR, are allotted with a higher number of bits, whereas less bits are allotted to sub-carriers experiencing attenuation, according to the concept of bit loading, which requires channel estimation. Since the symbol duration for each individual carrier increases, OFDM systems perform robustly in severe multi-path environments, and achieve a high spectral efficiency. Many of the techniques discussed above require underwater channel estimation, which can be achieved by means of probe packets [17]. An accurate estimate of the channel can be obtained with a high probing rate and/or with a large probe packet size, which however result in high overhead, and in the consequent drain of channel capacity and energy. Data link layer (MAC layer) The data link layer provides single hop data transmission capability; it will not be able to transmit a packet successfully if the destination node is not directly accessible from the source node. It may include some degree of reliability. It may also provide error detection capability (e.g. CRC check). In case of a shared medium, the data link layer must include the medium access control (MAC) sub-layer. Frequency division multiple access (FDMA) is not suitable for underwater sensor network due to the narrow bandwidth in underwater acoustic channels and the vulnerability of limited band systems to fading and multipath. Time division multiple access (TDMA) shows limited bandwidth efficiency because of the long time guards required in the underwater acoustic channel. In fact, long time guards must be designed to account for the large propagation delay and delay variance of the underwater channel in order to minimize packet collisions from adjacent time slots. Moreover, the variable delay makes it very challenging to realize a precise synchronization, with a common timing reference, which is required for TDMA. Carrier sense multiple access (CSMA) prevents collisions with the ongoing transmission at the transmitter side. To prevent collisions at the receiver side, however, it is necessary to add a guard time between transmissions dimensioned according to the maximum propagation delay in the network. This makes the protocol dramatically inefficient for underwater acoustic sensor network. The use of contention-based techniques that rely on handshaking mechanisms such as RTS/ CTS in shared medium access is impractical in underwater, for the following reasons: large delays in the propagation of RTS/CTS control packets lead to low throughput; due to the high propagation delay of underwater acoustic channels, when carrier sense is used, as in 802.11, it is more likely that the channel be sensed idle while a transmission is ongoing, since the signal may not have reached the receiver yet; the high variability of delay in handshaking packets makes it impractical to predict the start and finish time of the transmissions of other stations. Thus, collisions are highly likely to occur. Code division multiple access (CDMA) is quite robust to frequency selective fading caused by underwater multi-paths, since it distinguishes simultaneous signals transmitted by multiple devices by means of pseudo-noise codes that are used for spreading the user signal over the entire available band. CDMA allows reducing the number of packet retransmissions, which results in decreased battery consumption and increased network throughput. In conclusion, although the high delay spread which characterizes the horizontal link in underwater channels makes it difficult to maintain synchronization among the stations, especially when orthogonal code techniques are used [17], CDMA is a promising multiple access technique for underwater acoustic networks. This is particularly true in shallow water, where multi-paths and Doppler- spreading plays a key role in the communication performance. Network layer (Routing) The network layer is in charge of determining the path between a source (the sensor that samples a physical phenomenon) and a destination node (usually the surface station). In general, while many impairments of the underwater acoustic channel are adequately addressed at the physical and data link layers, some other characteristics, such as the extremely long propagation delays, are better addressed at the network layer. Basically, there are two methods of routing. The first one is virtual circuit routing and the second one is packet-switch routing. In virtual circuit routing, the networks use virtual circuits to decide on the path at the beginning of the network operation. Virtual-circuit-switch routing protocols can be a better choice for underwater acoustic networks. The reasons are: Underwater acoustic networks are typical asymmetric instead of symmetric. However, packet switched routing protocols are proposed for symmetric network architecture; Virtual-circuit-switch routing protocols work robust against link failure, which is critical in underwater environment; and Virtual-circuit-switch routing protocols have less signal overhead and low latency, which are needed for underwater acoustic channel environment. However, virtual-circuit-switch routing protocols usually lack of flexibility. In packet-switch routing, every node that is part of the transmission makes its own routing decision, i.e., decides its next hop to relay the packet. Packet-switch routing can be further classified into Proactive routing, Reactive and geographical routing protocols. Most routing protocols for ground-based wireless networks are packet-switch based. Proactive routing protocols attempt to minimize the message latency by maintaining up-to-date routing information at all times from each node to any other node. It broadcasts control packets that contain routing table information. Typical protocols include Destination Sequence Distance Vector (DSDV) [28] and Temporally Ordered Routing Algorithm (TORA). However, proactive routing protocols provoke a large signaling overhead to establish routes for the first time and each time the network topology changes. It may not be a good fit in underwater environment due to the high probability of link failure and extremely limited bandwidth there. Reactive routing protocols only initiate a route discovery process upon request. Correspondently, each node does not need to maintain a sizable look-up table for routing. This kind of routing protocols is more suitable for dynamic environment like ad hoc wireless networks. Typical protocol examples are Ad hoc On-demand Distance Vector (AODV) [23], and Dynamic Source Routing (DSR) [27]. The shortage of reactive routing protocols is its high latency to establish routing. Similar to its proactive counterpart, flooding of control packets to establish paths is needed, which brings significant signal overhead. The high latency could become much deteriorated in underwater environment because of the much slower propagation speed of acoustic signal compared with the radio wave in the air. Geographic routing (also called georouting or position-based routing) is a routing principle that relies on geographic position information. It is mainly proposed for wireless networks and based on the idea that the source sends a message to the geographic location of the destination instead of using the network address. Geographic routing requires that each node can determine its own location and that the source is aware of the location of the destination. With this information a message can be routed to the destination without knowledge of the network topology or a prior route discovery. Transport layer A transport layer protocol is needed in underwater sensor network not only to achieve reliable collective transport of event features, but also to perform flow control and congestion control. The primary objective is to save scarce sensor resources and increase the network efficiency. A reliable transport protocol should guarantee that the applications be able to correctly identify event features estimated by the sensor network. Congestion control is needed to prevent the network from being congested by excessive data with respect to the network capacity, while flow control is needed to avoid that network devices with limited memory are overwhelmed by data transmissions. Most existing TCP implementations are unsuited for the underwater environment, since the flow control functionality is based on a window- based mechanism that relies on an accurate esteem of the round trip time (RTT), which is twice the end-to-end delay from source to destination. Rate-based transport protocols seem also unsuited for this challenging environment. They still rely on feedback control messages sent back by the destination to dynamically adapt the transmission rate, i.e., to decrease the transmission rate when packet loss is experienced or to increase it otherwise. The high delay and delay variance can thus cause instability in the feedback control. Furthermore, due to the unreliability of the acoustic channel, it is necessary to distinguish between packet losses due to the high bit error rate of the acoustic channel, from those caused by packets being dropped from the queues of sensor nodes due to network congestion. In terrestrial, assume that congestion is the only cause for packet loss and the solution lies on decreasing the transmission rate, but in underwater sensor network if the packet loss is due to bad channel then the transmission rate should not be decreased to preserve throughput efficiency. Transport layer functionalities can be tightly integrated with data link layer functionalities in a cross-layer module. The purpose of such an integrated module is to make the information about the condition of the variable underwater channel available also at the transport layer. In fact, usually the state of the channel is known only at the physical and channel access sub-layers, while the design principle of layer separation makes this information transparent to the higher layers. This integration allows maximizing the