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cset2017-blog · 6 years

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News Story

New Mechanisms in Bat Echolocation Discovered

Scientists have known for almost a century that bats use echolocation to see in the dark, but Neuroscientist Cynthia Moss and Ornithologist Jinhong Luo at John Hopkins University in Baltimore, Maryland have used their bat flight chamber to discover a new way by which bats improve and adapt their echolocation: audiovocal feedback.

Bat echolocation, also know as bio sonar, is an evolutionary adaptation that allows bats to see in the dark. It consists of four simple steps: First, the bat generates ultrasonic waves from its larynx and emits them from its mouth in the direction that it intends to fly. Next, the waves bounce off any objects in the path of the beam and return to the bat. The bat then receives the waves into its ears, the same way that humans hear noises. Finally, the bat processes the information from its ears and knows that there is an obstacle in its path. This mechanism is so precise that bat echolocation can even detect an object the width of a human hair, and according to Cynthia Moss, echolocation is “comparable to what we [humans] get through vision.”

Audiovocal feedback is the processes by which an animal listens to both their own call and external noises and adapts their own calls, so that they can be easily discerned from the external noises. Audiovocal feedback is an adaptation that is found in a variety animals, not just those that possess echolocation. An example is a person raising their voice in a crowded room so as to be heard over others.

To study bat echolocation, the researchers used a state-of-the-art flight chamber with speakers, cameras, and microphones. The chamber is designed to monitor a bat while in flight and provide an array of information, including trajectory, wing movement, aim of the head, and the sounds generated by the bat.

The researchers discovered the role of audiovocal feedback by placing a series of Big Brown Bats in the chamber and monitoring their sonar call as the bats were blasted with simulated calls of other bats.The simulated calls lasted around ten milliseconds each and were generated by the scientists with the chambers speakers. The artificial calls served to jam, or cancel out, either the echo feedback or the audiovocal feedback available to the live bat. The researchers repeated this process individually on four different Big Brown Bats. The test was performed on each bat four times for a total of sixteen trials. The results showed that the bat would change the frequency and intensity of its own call much more drastically in the presence of a noise that jams audiovocal feedback than it would in the presence of a noise that jams echolocation feedback.

The researchers were able to show that bats rely more on audiovocal feedback than echo feedback when they need to know how to adapt their call’s frequency, something that was previously unknown. Moss says that through audiovocal feedback, “bats move their heads to sample information from closely spaced objects, just the way humans move our eyes.”

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cset2017-blog · 6 years

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Science Essay

Commodore’s Digest: for Vanderbilt Students

Vanderbilt’s Flying Squirrels and Their Defensive Adaptations

When walking across campus late one autumn night, while looking up at the stars, something moves in the corner of your vision and instantly catches your attention. Quickly redirecting your gaze, you see a palm-sized creature streak above your head and disappear into the branches of a nearby tree. Your first thought will most likely be “Oh my god, it’s a bat! Should I run?” Although this is a logical response, your fright is fortunately misplaced because the mysterious critter that you have just encountered is not a bat, or even a bird. In actuality, what you have seen is Glaucomys volans, or the Southern Flying Squirrel, a fairly unknown and unseen inhabitant of Vanderbilt.

Who can blame you for not recognizing the creature? Few students even realize that flying squirrels are indigenous to our campus, or even to Nashville. And, even fewer have ever seen one. In actuality, Southern Flying Squirrels can be found in not only Nashville but also the entire eastern seaboard of the United States. Furthermore, despite its name, which implies that they exist only in the South, the Southern Flying Squirrel lives in areas as far north as Canada. So why is it that so few people have seen one? This can attributed to the elusive behavior of these animals. You see, unlike the other, more evident rodent inhabitants of Vanderbilt, like the Grey Squirrel and the Chipmunk, the Southern Flying Squirrel is nocturnal and, therefore, rarely seen by students.

Nocturnality is one of the many adaptations that flying squirrels use to remain one step ahead, literally and figuratively, of its predators. Being nocturnal allows flying squirrels to utilize the shroud of darkness provided by the night and helps it to avoid the prime hunting time of its many predators, such as the hawk, which tend to hunt during daylight hours. To live its life in darkness, the Southern Flying Squirrel posses a special set of eyes which look like little jet-black marbles and are particularly large for its body size. These special eyes soak up every bit of available moonlight and allow flying squirrels to effectively see in the dark.

The Southern Flying Squirrel needs adaptations due to its physical size and lack of predatory features. An average Southern Flying Squirrel is only around nine inches in length, four inches of which are tail, fully stretched and weighs only about two ounces, only slightly heavier than a golf ball. As far as predatory features go, a flying squirrel’s diet is mostly composed of nuts, fruits, and vegetables with some occasional worms, so it has virtually no way to harm a predator. As far as physical defenses, a flying squirrel has no claws, only tiny hands that are smaller than a dime, and a circular mouth about the size of a pencil eraser that has only four teeth, two on the top and two on the bottom, that will do little against a hawk or house cat.

Another adaptation that provides security to the Southern Flying Squirrel is its coloration. In the same way as most birds, flying squirrels are colored in a way that optimizes camouflage while in flight. The top of the squirrel is always a variation of dark brown, while the underbelly is white. This coloration is beneficial to the squirrel in more than one way. The first way is that when on the ground or in a branch, only the brown part of the squirrel is exposed. This means that they blend in with their surroundings and become invisible to terrestrial predators. Furthermore, the flying squirrel’s coloration also provides cover while in flight. When looking up from below, the only part of the flying squirrel that is exposed is the white underbelly, which blends in with the surrounding sky. Also, the brown top of the squirrel blends in with the ground that it is flying over and makes the squirrel less visible to any flying predators that might be hovering overhead.

The last adaptation, and one one from which the Southern Flying Squirrel’s name is derived, is its ability to seemingly fly. Although this may look like what is happening to an onlooker, what the squirrel is actually doing is gliding. Even though gliding may not be as miraculous as flying, it still provides the Southern Flying Squirrel with its most invaluable tool for evading predators. Gliding allows a flying squirrel to move swiftly between neighboring trees, when avoiding predators, and out run virtually any terrestrial predator. It is the Southern Flying Squirrel’s unique anatomy that allows it to glide. The most important trait of this anatomy is the membrane of skin that extends from the flying squirrel’s hands to its feet on its sides. When spread out, these membranes allow the flying squirrel’s body to act as a sort of kite to catch the air and generate lift. The second trait which aids the squirrel’s flight is its unique tail. Different from the bushy tail of a standard squirrel, the flying squirrel’s tail is flat and feather-like. This flat tail is important because it allows the squirrel to control the direction of its flight by acting like a rudder when gliding and acting as a brake when landing.

With nocturnality that makes it elusive, coloration that makes it invisible, and flight that makes it quick, the Southern Flying Squirrel is truly a rare sight. So, it is of no wonder that very few students are aware of their existence on campus. But hopefully By: Elias Ladas 5 next time you're out at night, you’ll spot one gliding swiftly overhead and know exactly what it is you were lucky enough to see.

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cset2017-blog · 6 years

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Scientist Interview

Dr. Akunuri V. Ramayya is physics professor and Nuclear physics researcher at Vanderbilt University in Nashville, Tennessee. Dr. Ramayya received both a Bachelor’s and Master's degree from Andhra University in India and then moved to the United States to earn a Doctorate from Indiana University in 1964 . He has been active in the field of nuclear physics for over fifty years and has held tenure as a professor at Vanderbilt since 1980. Dr. Ramayya has been integral to many scientific breakthroughs over the years. However, his most recent and perhaps most important contribution to nuclear physics came in 2010 when he helped to synthesize Tennessine, a superheavy element with a proton number of 117 that belongs to the Halogen family. In collaboration with fellow Vanderbilt professor and long-time friend Joseph Hamilton, Ramayya brought together a team of scientists from both the US and Russia with the hopes of bombarding Berkelium-249, which has a proton number of ninety-seven, with a beam Calcium-48, which has a proton number of twenty, to form Tennessine. Although Tennessine itself is useless for practical applications, its creation is significant because it represents yet another step towards the next fabled island of stability. The next island of stability is a theoretical superheavy element which has an unknown proton number and a neutron number of 126 that will not instantly decay like current superheavy elements and will therefore have extensive real world applications. Elias Ladas was able to sit down with Dr. Ramayya to ask him a few questions about his background and research.

Where are you from? I am from India, but long time ago.

How long have you been teaching at Vanderbilt? For 50 years.

When and where did your research on Tennessine take place? This research took place in Dubna, the Georgia Institute for nuclear research. Sometime five years ago approximately. It takes quite a long time to do research of this type.

What was your role in the project? When we made the source in Oakridge and took the source to Dubna in Russia and then we were there during the first beam of Calcium-48. And then we didn't see anything at the time. It took about three or four months to see the first results.

Why did you choose to the two elements that you did for your cross? Calcium-48 is proton number twenty, Berkelium proton number is ninety-seven. Ninety-seven plus twenty is 117.

What were the project's biggest challenges? The biggest challenge was the background on the cross section. Also separating Berkelium from Californium. Berkelium-249 was the target, and calcium-48 is the beam.

What are the possible uses for Tenessine? Right now it's not many. OK. And probably none. It is just for research purposes. Its uses might come in the future if we can produce large quantities and reach the island of stability.

Where is the this new island of stability which you hope to reach? We don't know yet. Currently, the proton and neutron magic numbers which are very stable are hydrogen, helium, oxygen, calcium, tin, nickel, and lead.

Which do you enjoy more: teaching or researching? Oh yeah, I love teaching. Coming in contact with the students is always a fun thing. In fact, students keep us going. They give us the extra push, the energy.

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cset2017-blog · 6 years

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Final Paper

What is Genetic Counseling and How Will It Affect Our Lives?

The study of genetics has been around since the mid-1800’s, but only in the past one hundred years has science started to understand the mechanisms and impact of genetics. A major leap forward was made in 2003 when The Human Genome Project successfully mapped and quantified all the genes that make up a human’s genome. This project took almost fifteen years to finish and cost 2.7 billion 1991 US dollars, which means today it would have cost over 4.9 billion dollars. Luckily, gene mapping technology has made leaps and bounds in the past fifteen years alone, and today, companies such as 23andMe will map a person’s entire genome for only one hundred and fifty dollars. With this, one can find out not only their genetic predispositions but also their health risks and ancestry. Affordable genetic testing has opened up a whole new world of medicine that is revolutionizing the way you and I diagnose, treat, and prevent future medical crises. A person that specializes in dealing with humanity’s new found power to peer into and understand the genome is a genetic counselor.

So what is a Genetic Counselor, and what do they do exactly? A genetic counselor is a medical professional who is an expert in genetics and has received, at the very least, a master’s degree in genetic counseling from an accredited university. On top of that, most US states require a genetic counselor to be licensed with the American Board of Genetic Counseling, commonly known as the ABGC, which means the counselor has passed a certification test that ensures he or she is competent in their field. As for what a genetic counselor does, their job consists of two distinct duties. The counselor's first duty is the role of diagnosing a genetic condition. The second, and the part where a genetic counselor’s title actually comes from, is the role of counseling a patient on their options and concerns.

For the role of diagnosis, a genetic counselor has a number of invaluable tools at his or her disposal. They include, but are not limited to, familial history, physical exam, medical history, and of course genetic testing. The tool of familial history consists of gathering as much information from the patient about any diseases and conditions that have affected family members. Methods for collection include talking to not only the patient but also any available family members, preferably parents or grandparents. This tool is useful because genetic conditions usually run in a family. For example, if a person is suspected of having early-onset Alzheimer’s, it would be easily diagnosable if their mother or father also did.

A physical exam usually consists of analyzing physical appearance in order to make an inference about a condition. A physical exam is useful because it makes a disease that manifests itself physically easy to diagnosis. For example, if two parents bring in their baby, who is developing slowly, and want to know what is happening, Down syndrome would be easily diagnosed by simply analyzing physical features such as the baby’s height or the distance at which the baby’s eyes are separated with respect to the overall size of his or her face.

The tool of medical history involves analyzing a patient’s history of illness and symptoms to determine if there is possibly a pre-existing condition that has gone undiagnosed. A patient's medical history is important because it tells the genetic counselor how long a patient has had a condition and what sort of problems they have had in the past. For example, if a woman comes in complaining of long-term weight gain and tiredness and had a father with Hashimoto’s disease, an immune disease that affects the thyroid gland, it would be clear to a genetic counselor that the woman is suffering from an undiagnosed case of Hashimoto’s.

The last and by far most useful tool in a genetic counselor’s arsenal is genetic testing because through genetic research, geneticists have been able to pinpoint exact genes and mutations that code for a certain condition. So now, diagnosing a condition can be as simple as collecting a patient’s DNA and sending it into a genetics lab where scientists can scan for the presence, or hopefully absence, of a disease-causing gene. This is useful for many reasons. The most obvious reason is that it provides a fool proof diagnosis, since genetics do not lie. For example, if someone goes in for testing and bloodwork, finds that they possess the gene for sickle cell disease, then there is no question that they have the condition. Where as with the other tools such as familial history, a genetic counselor cannot say for sure if a patient inherited a gene or not, even if his or her parents do have the condition. Another reason that genetic testing is useful is that it works even in the absence of other information. It gives people such as orphans a way to find out their genetic history, even though they have no access to biological relatives. Yet another way in which genetic testing is invaluable is that it helps with the diagnosis of conditions that were acquired through mutations in a patient’s DNA, and a patient with a genetic condition that is acquired through mutation in his or her DNA will have no familial history of the disease. For example, if a man that appears to have Huntington’s disease, a brain-wasting condition that destroys cognitive function at an early age, has no familial history of the disease, a genetic counselor might be reluctant to make the diagnosis. But if genetic testing is done, the counselor can provide the patient with a concrete diagnosis.

Also, genetic testing is extremely useful when it comes to prenatal care. It allows a genetic counselor to provide a couple that is thinking of having a baby the option to test the genome of each parent and tell them about any risks that they might have of passing on a condition to their baby. For example, genetic testing might reveal that both parents possess a gene for an autosomal recessive disease, which means for someone’s baby to have a disease they must receive a gene for the disease from both of their parents. In this scenario, since both parents have one gene, their baby would have a twenty-five percent chance of being afflicted and a seventy-five percent chance of being unafflicted. Some parents might be fine with that risks, but for many, that is too great a risk to take, and they might choose to use a surrogate or sperm donor that does not possess the gene. This ensures that the couple’s baby will be unaffected because even a baby with one gene for the disease will not have it, since it is recessive.

This segways into the second part of a genetic counselor’s role: the actual counseling. A counselor’s purpose here is to simply tell a patient, or patients in the case of couples, their options. A counselor’s role, according to Melinda Cohen a retired certified genetic counselor, “is not telling what should do” but instead “is telling families what they can do.” On top of conveying information, a genetic counselor is also there to help a patient through the implications that the knowledge might have on them. Effects can include depression, guilt, low self-esteem, and relationship strain. For example, a person figuring out the reason their baby is never going to be normal will most likely feel guilty or may make the person’s partner resent them, and a genetic counselor is there to help the patient through this trying time in their life. Moreover, according to Ms. Cohen, there are five key principles that a genetic counselor must uphold when providing options and information to a patient. The first is non-maleficence, meaning cause no harm. The second is veracity, which means a counselor must always tell the truth. The third is autonomy, which means a counselor must respect a patient's decisions, wishes, and privacy when providing care. The fourth is beneficence, which means a counselor should aim to do good. And the last principle is justice, which means a counselor should always be impartial and just.

To investigate genetic counseling and its real-world applications, I interviewed two people that had been patients of a genetic counselor in order to find out their experiences and results. The first person I interviewed was a lady in her early fifties who went in for genetic counseling around a year ago. Her background was that her mother recently had a battle with breast cancer, and she wanted to know if she was genetically predisposed to developing breast cancer before it was too late. She suspected that she did inherit the predisposition, but she did not know because her mom is a heavy drinker, which can also lead to breast cancer. In this case, the gene being tested for was a mutation in either the woman’s BRCA1 or BRCA2 gene. These genes are important because they are a person’s tumor suppressor genes, meaning the genes prevent mammary cells from becoming cancerous, and if there is a mutation in either one, that means that they are not functional. Even a single mutated gene can lead to breast cancer, so testing can be life-saving. In this woman’s case, testing revealed that she did indeed have a mutation, and she was given two primary options by the genetic counselor: either get a double mastectomy, which is a procedure that removes a person’s mammary glands and prevents cancer, or go in for frequent mammograms, so that if she does develop cancer, it can be caught early. The woman ended up just deciding to go in for regular testing, since she lives “quite a bit healthier” than her mother and thought she had a good chance of not developing cancer.

The second person I interviewed was a mother of four who had taken her fourth child to a genetic counselor when he was an infant. The woman’s background was that she had already had three children that were completely healthy, but her fourth baby had a series of health problems that seemed to be pointing to him having cystic fibrosis. Also, the woman and her husband wanted a fifth child, so it was important to know if they were carriers of the autosomal recessive gene. The disease usually manifests itself as an overproduction of mucus in the respiratory and/or digestive tract. In this case, the baby was having digestive pain and had mucus/blood in his feces. Since the manifestation of the disease requires both parents to have the gene, the genetic counselor had both the woman and her husband tested. Luckily, the test revealed that neither had the gene. This test ruled out the possibility of cystic fibrosis, and it later turned out that the baby just had an autoimmune response to milk that was so severe it seemed like cystic fibrosis. The mom was “beyond happy” when she found out that her baby would be ok.

Each of these cases illustrates a perfect and ethical execution of the duties of a genetic counselor. Despite its good intentions and promising future, there are a few concerns for the uses of genetic testing in society. There are fears that genetics will lead to new problems in two areas that are already problematic: discrimination and inequality. Genetics can lead to discrimination because as genetic information becomes widespread on more and more people, institutions might start requesting it. For example if someone is found to be genetically predisposed to developing a disease, insurance companies might want to charge him or her more for coverage or companies might not want to hire this person. Also, genetics might lead to more inequality in the future as genetic therapies become available. Genetic therapy can be used to reverse diseases and alter genetic makeup, and since these procedures are expensive, only the rich will have access to them. This might lead to designer babies for rich people who excel in school and sports or reversal of Alzheimer's for a rich man, while an impoverished woman loses all her memories. Hopefully, as the wheels of progress turn, we as a society learn to face these new challenges ethically and fairly.

Works Cited

23andMe. “Find out What Your DNA Says about Your Health, Traits and Ancestry.” Our Health + Ancestry DNA Service - 23andMe, www.23andme.com/dna-health-ancestry/.

Cohen, Melinda P. “Ethical Dilemmas in a Genetic Clinic.” Human Biology Guest Lectures. 14 Nov. 2017, Nashville, Vanderbilt University.

“CPI Inflation Calculator.” U.S. Bureau of Labor Statistics, U.S. Bureau of Labor Statistics, data.bls.gov/cgi-bin/cpicalc.pl.

“Cystic Fibrosis - Genetics Home Reference.” U.S. National Library of Medicine, National Institutes of Health, ghr.nlm.nih.gov/condition/cystic-fibrosis.

“Genetic Counseling Prospective Student Frequently Asked Questions.” National Society of Genetic Counselors, www.nsgc.org/page/frequently-asked-questions-students.

“An Overview of the Human Genome Project.” National Human Genome Research Institute (NHGRI), www.genome.gov/12011238/an-overview-of-the-human-genome-project/.

“Prenatal Genetic Counseling.” Edited by Larissa Hirsch, KidsHealth, The Nemours Foundation, Apr. 2014, kidshealth.org/en/parents/genetic-counseling.html

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