Bats Echolocation Essay Example for Free

Bats Echolocation Essay Echolocation is the art which is utilized by many animals in the detection of their pray and for navigational purposes. These animals are generally not equipped with eyes that are functionally advanced to the extent that makes them a good predator in their habitat. Common examples of such animals are Bats, dolphins, whales etc.   Such animals emit an ultrasonic signal into the environment and sense the signal that returns back after striking from the surroundings. This enables them to appreciate what waits ahead of them, its range, size etc. In short echolocation works exactly like modern day sonar in which the animal makes an estimate of the range of the pray by calculating the time interval between its own emission of the sound and the echoes that return back. Bats use echolocation signals that range in the frequency from   14kHz to 1000khz (Neuweiler 245) .These signals are thus well out of the range of human ear to hear which is capable to decipher audio signals falling between the frequency of 20 Hz -20,000 Hz .. Studies have indicated that bats have a very characteristic pattern of hunting by echolocation that can be divided into four phases namely search phase, approach phase, terminal buzz and the post buzz phase. All these phases differ in their band width and inter pulse duration. When a bat is in flying smoothly in search of it’s pray it is said to be in the search phase which is characterized by pulses which have a comparatively low pulse repetition rate, a higher pulse duration and inter-pulse interval . When the pray is detected the signal is changed to the approach phase in which the interval between the pulses decreases to about 33 ms. Just before the capture of the pray most of the echo locating bats emit a terminal buzz, which has further decreased inter-pulse interval. The terminal buzz phase can also be divided into a Buzz I and Buzz II phase. Irrespective of the fact that a prey capture attempt is successful or not the same pattern of phases is repeated again during the course a bat is flying in search of its pray. To tell more simply the usual signals in the search phase are well separated and have a lesser rate/sec as compared to the signals which are released when the bat has spotted and is just approaching its target.   The pattern of the phases are however different which would be discussed later in the same article. One may be wondering what makes these animals utilize such advanced mechanisms to hunt for their pray. The answer lies in the fact that bats are provided with a highly sensitive inner ear (The part of the ear that detects and transmits hearing impulses to higher centers in the nervous system). In the same way bats have a very advanced auditory cortex in order to interpret these signals (Grinnell 25). Numerous studies have been conducted on the echolocation pattern of the bats; below it the summaries of some selected studies which would enable the readers in a better understanding of the topic. Although it is an extremely vast topic yet every effort is made to provide the summaries of recent five researches 1) Effects of successful capture attempt versus unsuccessful capture attempt on post-buzz period: Adam et al in their study demonstrated the effect of a successful catch over an unsuccessful attempt on the post-Buzz period. Post Buzz period is the interval that follows the terminal buzz till the usual pattern of the pulses, search phase is restarted. According to this study the post-buzz phase was significantly greater after successful attempts as compared to unsuccessful attempts.206 ±112.3ms for successful attempts and 106.2 ± 83.3 ms for unsuccessful attempts. This increase in the post-buzz period has been attributed to time that is required in the handling of the pray. Similar studies have indicated increase in post-buzz time upon the successful capture of the pray (Kalko 225). However the post-buzz time was shorter in this study than that found in that found by Adam et al possibly due to the use of smaller insects. So the pray size is also a determining factor in the duration of post-buzz interval. Similar results were obtained by a study done by Annemarie, Vibeke and Jakob Tougaard from the University of Southern Denmark. In addition to the calculation of post-buzz time for successful and unsuccessful attempts they also calculated the post-buzz periods for touches also, i.e. when a bat is unsuccessful in capturing the prey yet its body parts slightly touch the prey in flight. Similar to the previous studies the post-buzz period was greatest in successful catches 272.2 ms and shortest in unsuccessful attempts, 117.9 ms and almost a middle value in case of touches i.e. 181.2 ms. 2. Effect of the size of prey on the bat’s response time One might think that it makes sense if we say that larger prays are detected from a longer distance as compared to prays of smaller size. But in actual studies this belief has been negated. One of the studies indicated that there was no significant effect of the size of the pray on the reaction time of bats. The mean time from detection till attempted capture was 604 ±141 ms (Britton 1796). Similar results were found by Acharya and Fenton in their study titled â€Å"Echolocation behavior of vespertilionid bats attacking airborne targets including arctiid moths† 3. Echolocation frequency of bat species and its relation with geographical habitat: In a lot number of studies the interesting phemenon of the relationship between specific bat frequencies to their habitat was demonstrated. Gareth Jones and Sofie M. V Parijs demonstrated the presence of both high frequency and low frequency Pipistrelus bats in Britain. The echolocation signals of the low frequency bats were never found to exceed 52 KHz while that of the high frequency bats were usually above 52 KHz (Jones 123). They attributed this frequency difference to their geographical habitats.   In recordings from Scotland the high frequency bats which were found to be 71% clearly dominated the low frequency bats.   Thus it was concluded that in a particular geographical area different phenotypic bats having nearly similar echolocation frequencies of the same specie can exist and the change in frequency is not exhibited by the same phenotype which change its frequency according to ecological conditions. 4) Echolocation studies in Dolphins: Dolphins appear to have a lot more advanced echolocation system as compared to bats. They listen to their pray and then use echolocation signals to get more information about the pray (Harley 62). There is also a possibility that dolphins use echolocation signals for communication purposes as well this was proposed by Brownlee. Conclusion: Keeping in view the diversified studies that have been done on the echolocation patterns of bats one finds himself amazed to see what is known and highly curious about what is yet to be found out. Future works can target coding bat species according to their echolocation frequencies. Although this is not going to be an easy job but it is going to open windows to new dimensions of research. Through this coding an attribution to the geographical location of the bats can also be made.

henry ford :: essays research papers

  Ã‚  Ã‚  Ã‚  Ã‚   Henry Ford, born July 30, 1863, was the first of William and Mary Ford's six children. He grew up on a prosperous family farm in what is today Dearborn, Michigan. (Teachers D.) It was early on that Henry showed a strong dislike for his farm chores and interests in all types of mechanical things. (Editors 205.) In 1879 at the very young age of only sixteen Henry left home for Detroit the present day motor city.(Ford Motor C.) In Detroit Henry worked as an apprentice to a machinist.(Wik 190.) Returning home to help with farming from time to time he remained in his apprenticeship for 3 years.(Ford Motor C.) In the years to follow Henry more or less drifted in his work such as operating or repairing steam engines, finding occasional work in a Detroit factory, and over-hauling his father's farm implements, as well as lending a reluctant hand with other farm work.(Dahlinger 12.) However In 1889 with the marriage to his wife Clara Bryant he was forced to find a steady job to support them an d worked by running a saw mill. (Teachers D.)   Ã‚  Ã‚  Ã‚  Ã‚  In 1891, Ford became an engineer with the Edison Illuminating Company in Detroit. By doing making this decision it showed that Ford had decided to concentrate his job and work to industrial pursuits. His promotion to Chief Engineer in 1893 gave him enough extra time and money to devote attention to his personal experiments on internal combustion engines. (Yenne 150.) In 1896 his experiments produced a result; he made a quadricycle that had a steering wheel and a two speed engine with no reverse. (Teachers D.) Although this sounds like a very impressive feat Ford was not the first to build a self-propelled vehicle with a gasoline engine.   Ã‚  Ã‚  Ã‚  Ã‚     Ã‚  Ã‚  Ã‚  Ã‚  After two unsuccessful attempts to establish a company to manufacture automobiles, the Ford Motor Company was founded in 1903 with Henry Ford as vice-president and chief engineer. (Editors 9.) The small company produced only a few cars a day at the Ford factory on Mack Avenue in Detroit. Groups of two or three men worked on each car from components ordered in by other companies. (Yenne 45) Henry Ford realized his dream of producing an automobile that was reasonably priced, reliable, and efficient with the introduction of the Model T in 1908. (XXXX) â€Å"This vehicle initiated a new era in personal transportation. It was easy to operate, maintain, and handle on rough roads, immediately becoming a huge success.

Social Studies Teenage Pregnancy Questionnaire SBA

SOCIAL SUDIES SCHOOL BASED ASSESSMENT (SBA) 2013 CANDIDATE NAME: MITSEY STONE SCHOOL: MONTEGO-BAY E-LEARNING TITLE: An examination on Teenage Pregnancy in my community TABLE OF CONTENTS Acknowledgement Introduction Task 1: Statement of Problem Task 2: Reason for Selecting Area of Research Task 3: Method of Investigation Task 4: Data Collection Instrument Task 5: Procedures for Data Collection Task 6: Presentation of Data Task 7: Analysis and Interpretation of Data Task 8: Statement of FindingsTask 9: Recommendations and Implementation StrategyACKNOWLEDGEMENTI have taken effort in this project; however it would not have been possible without the kind support and help of many individuals and book publishers. I would like to extend my sincere thanks to all of them. I am highly indebted to Modules In Social Studies by Rampersad Ramsawak and Ralph . R Umraw for providing necessary information regarding this rese- arch. I would like to express my gratitude towards my family ,friends and the the persons in my community who participated,for their kind o-operation and encouragement which help me in completion of this project, And most of all to God for making this possible.INTRODUCTION TASK 1: STATEMENT OF PROBLEMWhat factors contribute to the increasing problem of teenage Pregnancy?How does this problem impact the lives of children?What can be done to decrease the cause of teenage pregnancy?TASK 2: REASONS FOR SELECTING THIS AREA OF RESEARCHThis area of research was chosen because it is a prominent issue that could be address in a better light. Similar essay: SBA on Drug AbuseThe researcher want to explore the options or me- asures that can assist these teenagers and also what can be done to eliminate the increase of teenage pregnancy in the community of Maroon Town.TASK 3: METHOD OF INVESTIGATION The method of investigation chosen to implement data is in the form of a questionnaire that was shared randomly to persons within my community.TASK 4: DATA COLLECTION INSTRUMENT QUESTIONNAIRE Instructions: Please read the following questions and put a tick in the box provided or answer on the spaces.1. Sex: Male Female2. To which age group do you belong ? 9- 12 years, 13- 15 years, 16- 19 years, 20- 50 years3. How long have you been a resident of this community? 3- 5 years, 7- 10 year,s 12- 15 years, Others4. To which ethnic group do you belong? African decent, Indian decent, Chinese decent, Other5. What is your level of education? Primary, Secondary, Tertiary6. What is the highest grade you completed? 8- 9 grade, 10- 11 grade, So me college, Other7. At what age did you become sexually active? 11- 13 years, 14- 16 years, 17- 18 years, 19- 20 years8.How many children do you have? 1-2 children, 3- 4 children, Over 5 children, Others9. How did you first find out about sex? Family, Friends, School, Media, Other10. What is your main source of financial support? Own job, Spouse, Parents, Other11. Are you currently working? Yes No12. If not why?13. Do you think that peer influences affect your opinion on sex? Yes No14. What are the main causes of teenage pregnancy? Lack of parental guidance, Sexual assault or rape, Economic issues Poverty15. How does teenage pregnancy affect a teenagers education?16. What are the advantages and disadvantages or teenage pregnancy?17. What were the challenges faced during your pregnancy?18. What measures can be taken to reduce the cause of teenage pregnancy in my community?TASK 5: PROCEDURES FOR COLLECTING DATA To gather information for this project the researcher constructed a questi onnaire which consist of eighteen questions which were con- tributed to thirty teenagers in Maroon Town. The sample was selec- ted using the simple method by placing fifty names of persons in my community in a bag.The bag was shaken and the first twenty names selected were given a questionnaire to complete. The questionnaire were contributed on the 30th October and collected the 6th of November. Of the respondents 70percent were female and 30percent were male.TASK 6: PRESENTATION OF DATA Data was collected for this project using a pie chart, a histogram and a bar graph. Figure 1 Figure one is a pie chart illustrating the ages at which teenagers became sexually active in the community of Maroon Town. An estimate of 40% became pregnant at the age of 14 to 16 years

Honors Chem - 1231 Words

Directions: The following questions involve more practice with radioactive decay half-life. Complete the problems to the best of your ability. This assignment is due by next WEDNESDAY, November 16th. 1. If 100.0 g of carbon-14 decays until only 25.0 g of carbon is left after 11 460 y, what is the half-life of carbon-14? a. Calculate how many half-lives have passed during the decay of the 100.0 g sample. 100 grams/2 50 grams/2 25grams†¦2 half lives have passed b. Solve for the half-life. 11,460year/2 half lives = 5,730 years half-life of carbon – 14 2. What is the half-life of a 100.0 g sample of nitrogen-16 that decays to 12.5 g of nitrogen-16 in 21.6 s? 100g50g25g12.5g†¦3 half lives have passed 21.6s/3 half†¦show more content†¦150days/30days = 5 half lives have passed 200mg/2 100mg/2 50mg/2 25mg/2 12.5mg/2 6.25mg of polonium – 210 remain 16. A 1000 gram sample of Titanium-50 decays to 62.5 grams in 2000 years. What is the half-life of Titanium-50? 1000g/2 500g/2 250g/2 125g/2 62.5g †¦ 4 half lives have passed 2000years/4 half lives = 500years half-life of Titanium – 50 17. The half-life of Potassium-44 is 10 days. If after 50 days you end up with 15 grams of Potassium-44, how many grams did you start with? 50days/10days = 5 half lives have passed WORKING BACKWARDS in time†¦ 15g x 2 30g x 2 60g x 2 120g x 2 240g x 2 480g †¦amount of potassium – 44 you started with 18. The half life of Carbon-14 is 5730 years. A scientist finds a 17190 year old fossil of a bumble bee. A live bumble bee of this kind has 600 million atoms of Carbon-14. How many atoms of Carbon-14 are in this fossil? 17,190years/5,730years = 3 half lives have passed 600 million atoms/2 300 million atoms/2 150 million atoms/2 75 million atoms of carbon – 14 are found in this fossil 19. The half life of Polonium-210 is 140 days. 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