Thesis (Ph. D.)--Massachusetts Institute of Technology, Microbiology Graduate Program, 2013. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 91-96). / Integrative and conjugative elements (ICEs) are widespread mobile genetic elements that are integrated in bacterial chromosomes, but can excise and transfer to a recipient through conjugation. ICEs are important agents of evolution, contributing to the acquisition of new traits, including antibiotic resistance. Many ICEs are site-specific in that they integrate preferentially into a primary attachment site in the bacterial chromosome. Site-specific ICEs can integrate into secondary locations, but little is known about the consequences of integration. Using ICEBs1, a site-specific ICE from Bacillus subtilis, I found that integration into secondary attachment sites is detrimental to both ICEBs1 and the host cell. Integration at secondary locations is detrimental to ICEBsJ. Once integrated in the chromosome, excision of ICEBs1 from all secondary attachment sites analyzed was either reduced (4 sites) or undetectable (3 sites) compared to ICEBs1 excision from the primary site. Additionally, from two of the four secondary sites that exhibited reduced but detectable excision, the excised, circular form of ICEBs1 was present at lower levels than expected, indicating that circular ICEBs1 may be unstable. Defects in excision and stability of ICEBs] severely limit its ability to spread to other cells. Integration at secondary locations is detrimental to the host cell. Induction of ICEBs1 gene expression in secondary integration sites resulted in a defect in cell proliferation and/or viability, as well as induction of the SOS response. These effects are likely due to DNA damage resulting from plasmid-like, rolling-circle replication of the excision-defective ICEBs1 in the chromosome. Consistent with this model, deletion of ICEBs] replication genes (nicK and helP) alleviated the proliferation and viability defects. Implications for the evolution of ICEs. These previously unrecognized detrimental effects may provide selective pressure against propagation of ICEBs1 in secondary attachment sites. Such detrimental effects could explain the maintenance and prevalence of site-specific integration among ICEs. / by Kayla L. Menard. / Ph.D.

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2006. / Vita. / Includes bibliographical references (p. 47). / Older adults are susceptible to the same mental afflictions that affect other age groups; depression, anxiety disorders, schizophrenia, and other illnesses affect all adult age groups to varying degrees. Yet despite recent improvements in the research attention given to mental disorders and reductions in the stigma against such illnesses in younger age groups, the elderly remain a vastly underserved segment of the population in both mental health research and care. They are not underrepresented in numbers, however: the National Institutes of Health place the population of adults 65 and older "on the threshold of a boom," predicting that the age group will include 72 million individuals by the year 2030 and comprise 20 percent of the U.S. population. The trend is expected to begin in earnest when the first Baby Boomers turn 65 just five years from now, in 2011. Yet despite these numbers and the population's high risk of mental illness - the elderly are more prone to mental illness than any other age group - the U.S. health system remains grossly unprepared for the mental health needs of the elderly population. / (cont.) Its major problems include a shortage of caregivers, a notable lack of successful treatment methods, a dearth of research on the aspects of mental illness specific to the elderly, and a lack of funding to facilitate such research. With less than five years left before the first wave of this massive population growth begins, experts unequivocally agree that the nation is already in a crisis. This thesis documents the medical, social, and political challenges facing patients, researchers, advocates, clinicians and caregivers in the coming decades - and today. / by Michelle Sipics. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2006. / "September 2006." / Includes bibliographical references (leaves 38-39). / Grigori Perelman, a reclusive Russian mathematician, may have proved the Poincare Conjecture, a statement first poised by Jules Henri Poincare in 1902. The problem is the most eminent challenge in the mathematical field of topology. Perelman posted his proof on the online informal preprint server at arXiv.org. His proof leaves a number of details unexplained. Although he initially participated in the verification of his proof, answering questions to help people understand his work, in the last year Perelman has effectively disappeared from the mathematical community. His absence has caused some controversy in the world of mathematics, where individual mathematicians are usually expected to support their own results. In the wake of his disappearance, other mathematicians are coming together to pore over his work and try to flesh out the details. His apparent desertion raises questions both about the personal risk of mathematicians working at the highest level and the responsibility of the mathematical community in the verification process. / (cont.) These questions are further complicated by the fact that the Poincare Conjecture is one of seven problems that was selected by the Clay Mathematics Institute as a Millennium Prize Problem. If a mathematician solves one of the problems, he or she will receive $1 million from the institute. If Perelman's work turns out to point the way to the prize, then the Clay Institute will have to decide how to distribute both credit and the hefty monetary prize. / by Stephen Ornes. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2007. / "September 2007." / Includes bibliographical references (leaves 44-49). / On May 11th 1997, the world watched as IBM's chess-playing computer Deep Blue defeated world chess champion Garry Kasparov in a six-game match. The reverberations of that contest touched people, and computers, around the world. At the time, it was difficult to assess the historical significance of the moment, but ten years after the fact, we can take a fresh look at the meaning of the computer's victory. With hindsight, we can see how Deep Blue impacted the chess community and influenced the fields of philosophy, artificial intelligence, and computer science in the long run. For the average person, Deep Blue embodied many of our misgivings about computers becoming our new partners in the information age. For researchers in the field it was emblematic of the growing pains experienced by the evolving field of AI over the previous half century. In the end, what might have seemed like a definitive, earth-shattering event was really the next step in our on-going journey toward understanding mind and machine. While Deep Blue was a milestone - the end of a long struggle to build a masterful chess machine - it was also a jumping off point for other lines of inquiry from new supercomputing projects to the further development of programs that play other games, such as Go. Ultimately, the lesson of Deep Blue's victory is that we will continue to accomplish technological feats we thought impossible just a few decades before. And as we reach each new goalpost, we will acclimate to our new position, recognize the next set of challenges before us, and push on toward the next target. / by Barbara Christine Hoekenga. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2007. / "September 2007." / Includes bibliographical references (leaves 36-37). / The human voice is an important indicator of a person's gender. For male-to-female transgender individuals (or transsexuals) the voice is one of the most difficult parts of the gender transition. Males have larger and heavier vocal apparatuses (larynx and vocal folds), which generally produce a lower sound. Transgender women can have voice surgery, but it can sometimes cause a Minnie Mouse-like falsetto or the complete loss of the voice. As a result, many transgendered women turn to specially trained voice therapists to learn how to speak more convincingly like women. The voice's pitch, although important, is not the only factor in creating a more female sound. Intonation, resonance, volume, speech patterns and formant frequencies also play significant roles in making a realistic feminine sound. There continue to be many unanswered questions about how listeners perceive the voices of transgender women and how best to blend the voices of transwomen into a comfortable range. Transgender women have many hurdles to face as they transition from male to female, and possessing an authentic voice is a way to smooth out the bumpy path they face. / by Katharine Stoel Gammon. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2007. / Includes bibliographical references (leaves 49-51). / In the MIT lab of neuropharmacologist Richard Wurtman, rodents that received a new Alzheimer's drug have shown a marked improvement in learning and memory. They are able to master elaborate mazes in half the time of their all-natural counterparts. Wurtman theorizes that the memory loss and dementia associated with Alzheimer's disease is caused not by amyloid plaques and tangles but by a gradual deterioration of the brain's synapses. Wurtman's drug-a cocktail of three dietary supplements including uridine, choline, and an omega-3 fatty acid called DHA-is designed to generate more synapses. The three ingredients deliver the stimulus and raw material needed to create more phosphatidylcholine, a major component of neuronal membrane. More membrane, the thinking goes, means more neuronal encounters, more synapses, and more relayed messages. Wurtman's cocktail has just entered a massive clinical trial involving 10,000 Alzheimer's patients spread across 10 European countries. The same drug that could preserve brain function in Alzheimer's patients also has potential as a memory drug for healthy people. This thesis explores the ethical questions surrounding such biotechnological enhancement. What might be the benefits and drawbacks of taking a memory booster? Could a class-like division eventually arise between those who get the drug and those who do not? Could the molecular manipulations of a smart drug-what some call "cosmetic pharmacology"--change qualities that are inextricable from who we are? / by William Dowd. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2008. / Includes bibliographical references (leaves [38]-[41]). / The current biofuels market in the United States is dominated by ethanol made from corn. But corn ethanol has limitations that will prevent it from displacing a large amount of fossil fuel use in the U.S. To achieve that goal, biofuels will need to come from different sources. Cellulose, one of the main candidates, looks like it could provide a much higher volume of ethanol. The Department of Energy has sponsored new research centers to investigate cellulosic ethanol and improve the technology necessary to produce it. Even so, questions remain about the true potential of biofuels in the future alternative energy market. / by Andrew Moseman. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 31-35). / "Reentry" most often evokes an image of the space shuttle flying through earth's atmosphere, glowing hot from friction, then landing on the runway and rolling to a halt. By then, the astronauts' job is finished. The hard part is over. Adjusting after six months in space - or even two weeks - should be a snap. But there's more to coming home than landing on solid ground. This thesis presents the little-known story of what happens once the Space Shuttle or Soyuz capsule returns to earth. It covers physical effects on astronauts transitioning from microgravity to earth gravity, as well as psychological effects such as post-flight depression, reintegration with family, frequent travel for publicity, and getting back to normal life. In addition to reference books, articles and memoirs, this thesis draws on interviews with shuttle and space station astronauts, NASA flight surgeons, medical researchers, and psychological support personnel to describe a part of the space program the public rarely sees. / by Anne-Marie Corley. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 37-42). / This thesis, written for a popular audience, explores the many facets of the placenta, an organ that facilitates the growth of the fetus during pregnancy. It looks at what happens when the placenta dodges the hospital incinerator-taking on a second purpose, a second life. Once the placenta is expelled during the third stage of labor, once it has served its role in the body and is facing retirement, it can take on whole new forms of usefulness. Humans, artful at manipulating the materials of life, have created new-and often controversial-purposes for this discard tissue after it has served its primary role: expelled placenta is used in eye surgery, in training dogs to sniff dead bodies, in toxicology research, in forensics, in cosmetics, and, most significantly, in an emerging field of stem cell research. From ritual use to research subject to health treatment, we have taken the placenta from the realm of the dead and given it new vigor. / by Anne O. Glausser. / S.M.in Science Writing

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2008. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 42-45). / Market mechanisms for controlling pollution and other environmental problems, once considered experimental, have recently become favored tools for regulation, both in the U.S. and abroad. In the last several years, a $64 billion global market for carbon dioxide permits and offsets has emerged out of international deal-making on climate change. The carbon market has become a force to be reckoned with in international trade, and created many stakeholders with vested interests in the design of the market and its governing regulations. Driven by the international finance community and clamor from the general public for action on global warming, U.S. legislators are under increasing pressure to adopt similar measures. And as action by the U.S. seems more likely, industries that would likely be targeted by climate change legislation are becoming less obstructionist, increasingly seeking influence over the direction of regulation rather than attempting to block it altogether. Given current trends in business, finance and politics, it is likely that in the near future, the U.S. will adopt carbon pricing as a means to decrease carbon emissions and attempt to halt the progress of climate change. However, with so many stakeholders in the debate, designing the market will be a contentious and highly politicized process. Because of both scientific uncertainty and political factors, there is great potential for market failures, from miscounted emissions to perverse incentives to social inequity. This thesis examines some of the market designs that have been proposed, along with reasons why the carbon market is likely to fail to live up to its greatest promise. / by Lissa Harris. / S.M.in Science Writing