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News Article | May 8, 2017
Site: www.eurekalert.org

A watch that rotates, hinges, translates, orbits and rises to the occasion IMAGE:  The Cito prototype rotates, hinges, translates, rises and orbits to add convenience for smartwatch users. view more In an effort to make digital smartwatches more convenient for their users, researchers at Dartmouth College and the University of Waterloo have produced a prototype watch face that moves in five different directions. With the ability to rotate, hinge, translate, rise and orbit, the model dramatically improves functionality and addresses limitations of today's fixed-face watches. The concept, named Cito, will be presented on May 10 at the ACM CHI Conference on Human Factors in Computing Systems in Denver, Colorado. "Users want smartwatches that fit their lifestyles and needs," said Xing-Dong Yang, assistant professor of computer science at Dartmouth. "The Cito prototype is an exciting innovation that could give consumers even more great reasons to wear smartwatches." Most smartwatch research primarily addresses how users can more easily input information. Cito, designed and engineered by Jun Gong, Lan Li, Daniel Vogel, and Yang, aims to remove awkward moments associated with using smartwatches by improving how the device presents data to the wearer. Examples of watch movement - or actuation -include automatically orbiting around the wristband to allow viewing when the wrist is facing away from the user; rising to alert the wearer of a notification if the user is playing a game; hinging to allow a companion to view the watch face; and translating to reveal the watch face from underneath a shirt sleeve. "Consumers will question the need for smartwatches if the devices are just not convenient enough. Cito proves the true potential of smartwatches and shows that they can be functional and fun," said Yang. According to a research paper submitted at CHI 2017, the five watch face movements can be performed independently or combined. Beyond making the watches more convenient for users, the technology can provide important benefits to wearers with physical disabilities or other impairments. The design concept is the latest innovation from the same Dartmouth lab that has studied other smartwatch innovations including Wrist-Whirl, a smartwatch that uses the wrist as a joystick to perform gestures and Doppio, a smartwatch with dual touchscreens. "We recognize that our work investigates a radical idea, but our hope is that we also show how a methodical and principled approach can explore any such radical visions," the research team said in its paper. In developing the prototype, researchers conducted two separate studies to confirm the usefulness, social acceptability and perceived comfort of different watch movements and usage contexts. With continued research, the team is planning to integrate innovations like an ultra-sonic motor to reduce bulk and increase battery life to make the actuated watch technology more practical. Xing-Dong Yang may be contacted at: Xing-Dong.Yang@dartmouth.edu Watch a video featuring the Cito prototype at this link. Hi-res photos are available upon request. Dartmouth has TV and radio studios available for interviews. For more information, visit: http://www. Founded in 1769, Dartmouth is a member of the Ivy League and offers the world's premier liberal arts education, combining its deep commitment to outstanding undergraduate and graduate teaching with distinguished research and scholarship in the arts and sciences and its three leading professional schools: the Geisel School of Medicine, Thayer School of Engineering and Tuck School of Business.

News Article | July 12, 2017
Site: www.eurekalert.org

International experts on mercury will meet at the 13th International Conference on Mercury as a Global Pollutant (ICMGP 2017) in Providence, Rhode Island from July 16 to 21. The conference aims to share science and develop measures to decrease human and wildlife exposure to the poisonous metal. With the theme of integrating mercury research and policy in a changing world, this year's conference comes one month before entry into force of the Minamata Convention on Mercury. The global treaty requires countries to control new and existing mercury sources and to monitor the effectiveness of those controls. "Mercury is a widespread global pollutant with impacts on human health largely through fish consumption," said Celia Chen, co-chair of ICMGP 2017 and mercury project leader of the Dartmouth Toxic Metals Superfund Research Program. "Human activity is an important cause of mercury pollution and human health suffers because of it, so it is important to have scientific study, innovative management strategies and cooperation among all nations to reduce the negative impacts of mercury." Mercury is a complex contaminant and a known neurotoxin for humans and wildlife. Methylmercury, the more toxic form of the metal, increases in concentration as it moves up the food chain and is the cause of most mercury-related fish consumption advisories and wildlife impacts. Mercury transport, transformations, bioaccumulation and exposure are affected by climate change, nutrient loading, land use, food web dynamics, human behavior and decision making. Concentrations of mercury in the environment have increased in the last century largely due to human activities such as coal combustion, chemical manufacturing and mining. In the U.S., the implementation of the Mercury and Air Toxics Rule limits power plant emissions of mercury and other toxic air pollutants. In many countries, the use of mercury in artisanal gold mining is under investigation as the magnitude of associated mercury releases and effects have been underestimated. Under the ICMGP 2017 theme, the conference will improve understanding of the complex factors that accelerate and reduce recovery from mercury contamination at local to global scales. "We have made considerable progress in mercury regulations to control the release of this toxic metal, and efforts are underway at the local level to remediate mercury contaminated sites," said Charles Driscoll, ICMGP 2017 co-chair and a professor of environmental systems engineering at Syracuse University. "At the same time, uncertainty remains over the levels of exposure linked to a range of effects of mercury on wildlife and human health. While these initiatives are important steps to mitigate mercury contamination, the extent and rate of recovery is unclear due to uncertainties in our understanding of mercury transport, cycling and trophic transfer and under changing climate." The Dartmouth Toxic Metals Superfund Research Program is an ICMGP 2017 co-sponsor. Chen will lead a one-day workshop on Sunday, July 16 that brings together mercury researchers and policymakers to integrate policy questions and science needs into four synthesis papers, which have been based on the meeting themes of the conference. The papers will be published in a special section of the journal Ambio. A widely-recognized expert on the fate and effects of metal contaminants in aquatic food webs both in freshwater and estuarine ecosystems, Chen is also the leader of the research translation core for the Dartmouth Toxic Metals Superfund Program and is a research professor of biological sciences at Dartmouth College. "By providing the opportunity for face-to-face communications between mercury science experts and national and international policymakers, this workshop encourages a dialogue to address the questions policymakers need answered by scientific research," said Chen. The ICMGP Executive Committee is responsible for the organization of the conference and is comprised of: Kimberley Driscoll, Syracuse University; David Gay, University of Illinois; Betsy Henry, Anchor QEA; Robert Mason, University of Connecticut; Noelle Selin, Massachusetts Institute of Technology; and Marcella Thompson, University of Rhode Island. Celia Chen can be contacted at: celia.y.chen@dartmouth.edu. Charles Driscoll can be contacted at: ctdrisco@syr.edu. Founded in 1769, Dartmouth is a member of the Ivy League and offers the world's premier liberal arts education, combining its deep commitment to outstanding undergraduate and graduate teaching with distinguished research and scholarship in the arts and sciences and its three leading professional schools: the Geisel School of Medicine, Thayer School of Engineering and Tuck School of Business.

News Article | June 7, 2017
Site: www.eurekalert.org

HANOVER, N.H. - June 7, 2017- Researchers at Dartmouth College have developed a new material that scrubs iodine from water for the first time. The breakthrough could hold the key to cleaning radioactive waste in nuclear reactors and after nuclear accidents like the 2011 Fukushima disaster. The new-generation microporous material designed at Dartmouth is the result of chemically stitching small organic molecules to form a framework that scrubs the isotope from water. "There is simply no cost-effective way of removing radioactive iodine from water, but current methods of letting the ocean or rivers dilute the dangerous contaminant are just too risky," said Chenfeng Ke, assistant professor in the Department of Chemistry at Dartmouth College. "We are not sure how efficient this process will be, but this is definitely the first step toward knowing its true potential." Radioactive iodine is a common byproduct of nuclear fission and is a pollutant in nuclear disasters including the recent meltdown in Japan and the 1986 Chernobyl disaster. While removing iodine in the gas phase is relatively common, iodine has never been removed from water prior to the Dartmouth research. "We have solved the stubborn scientific problem of making a porous material with high crystallinity that is also chemically stable in strong acidic or basic water," said Ke, the principle investigator for the research. "In the process of developing a material that combats environmental pollution, we also created a method that paves the way for a new class of porous organic materials." The research, published in the May 31 issue of the Journal of the American Chemical Society, describes how researchers used sunlight to crosslink small molecules in large crystals to produce the new material. The approach is different from the traditional method of combining molecules in one pot. During the research, concentrations of iodine were reduced from 288 ppm to 18 ppm within 30 minutes, and below 1 ppm after 24 hours. The soft stitching technique resulted in a breathable material that changed shape and adsorbed more than double its weight of iodine. The compound was also found to be elastic, making it reusable and potentially even more valuable for environmental cleanup. According to Ke, the compound could be used in a manner similar to applying salt to contaminated water. Since it is lighter than water, the material floats to adsorb iodine and then sinks as it becomes heavier. After taking on the iodine, the compound can be collected, cleaned and reused while the radioactive elements are sent for storage. The lab research used non-radioactive iodine in salted water for the experiment, but researchers say that it will also work in real-world conditions. Ke and his team hope that through continued testing the material will prove to be effective against cesium and other radioactive contaminants associated with nuclear plants. "It would be ideal to scrub more radioactive species other than iodine--you would want to scrub all of the radioactive material in one go," said Ke. Researchers at Dartmouth's Ke Functional Materials Group are also hopeful that the technique can be used to create materials to target other types of inorganic and organic pollutants, particularly antibiotics in water supplies that can lead to the creation of super-resistant microorganisms. Note to reporters: A .pdf of the paper is available upon request. Hi-res images from the study are also available. Founded in 1769, Dartmouth is a member of the Ivy League and offers the world's premier liberal arts education, combining its deep commitment to outstanding undergraduate and graduate teaching with distinguished research and scholarship in the arts and sciences and its three leading professional schools: the Geisel School of Medicine, Thayer School of Engineering and Tuck School of Business. Dartmouth has TV and radio studios available for interviews. For more information, visit: http://www.

News Article | June 19, 2017
Site: www.eurekalert.org

HANOVER, N.H. - June 19, 2017 - New research from Dartmouth College raises questions over how scientists should interpret observed groupings of bacteria. The study advises caution with the assumption that bacterial clusters are always a result of ecological and genetic forces. The research, appearing in the Proceedings of the National Academy of Sciences, says random diversification and extinction of cells could organize bacteria into taxonomic units just as effectively as classification based on selection-driven ecological forces. "A reliable classification system is the key to understanding microbial biodiversity," said Olga Zhaxybayeva, assistant professor of biological sciences at Dartmouth College. "Through our research, we found that organizing microorganisms is even trickier than previously thought." Scientists are currently divided over what factors to consider when classifying bacteria and other microorganisms. Some favor the so-called "periodic selection" model, in which the descendant of the most-fit genotype takes over the population and establishes a new group. Others advocate the "recombination" model, in which the frequent exchange of material between genes within bacterial populations causes organisms to cluster. "Not knowing what is driving the organization of microorganisms makes the task of providing fast, accurate identification of bacteria difficult," said Zhaxybayeva. "Surprisingly, we found that a simple alternative may also explain grouping patterns, eliminating the need to invoke current models." The research team, led by Zhaxybayeva, tested the idea that a simple birth-death cycle of cells can produce microbial clusters that look like groupings observed in nature. Analysis of hundreds of genomes within four bacterial groups - Escherichia spp., Borrelia spp., Neisseria spp. and Helicobacter pylori - produced patterns indistinguishable from those observed in most genes from three of the four bacterial groups. As a result of the findings, the study recommends checking diversification of microbial groups against the proposed birth-death model before calling for more complex explanations. Note to reporters: A .pdf of the paper is available upon request. Founded in 1769, Dartmouth is a member of the Ivy League and offers the world's premier liberal arts education, combining its deep commitment to outstanding undergraduate and graduate teaching with distinguished research and scholarship in the arts and sciences and its three leading professional schools: the Geisel School of Medicine, Thayer School of Engineering and Tuck School of Business. Dartmouth has TV and radio studios available for interviews. For more information, visit: http://www.

News Article | September 25, 2017
Site: www.eurekalert.org

Researchers at Dartmouth College have developed a technique to produce synthetic steroids that could pave the way for a cascade of new drug discoveries. The process, published in the journal Nature Chemistry, facilitates access to rare, mirror-image isomers of naturally occurring steroid structures. The technique, based on a series of new chemical reactions, significantly reduces the expense and time needed to develop therapeutics from a pharmaceutically privileged yet underexplored collection of molecules. "This is a fundamentally new molecular strategy for steroid construction," said Glenn Micalizio, the New Hampshire Professor of Chemistry at Dartmouth. "This technology allows the preparation of either mirror-image isomer with equal ease, but with unprecedented efficiency." The core molecular structure of steroids is a proven backbone in drug development. More than 100 different steroid molecules are approved by the U.S. Food and Drug Administration as therapeutics for a wide range of symptoms and diseases including inflammation and pain, cancer and bacterial infection. Steroidal therapeutics arguably make up the most successful class of medicine inspired by a natural product. All known drugs in this class share a common structure comprised of only one of two possible mirror image skeletons - known as enantiomers. Such agents are typically available from chemical transformations of natural and readily available steroids. According to researchers, molecules based on the unnatural mirror image isomer of steroids form the foundation of a vast collection of underexplored potential medicines. While these compounds share the basic drug-like physical properties of the natural class, they boast complementary 3-D structures with broad potential in the clinic. "With this advancement, we now have the opportunity to investigate fertile regions of chemical space for the identification of untold numbers of unique, medicinally relevant agents," said Micalizio. The process developed in the Micalizio Laboratory at Dartmouth, produces steroidal structures of either enantiomer with what researchers describe as unprecedented efficiency. Using inexpensive and abundant starting materials, the new class of synthetics can be produced in as few as five chemical steps. The advance is based on a chemical reaction discovered in 2014 by Micalizio that forges half of the steroid structure. The breakthrough was made possible by inventing a simple procedure to advance these intermediates to steroid structures of either mirror image series. While chemical synthesis has previously been described as a route to unnatural enantiomers of steroids, the process pioneered at Dartmouth allows scientists to more easily investigate their medicinal properties. Importantly, the time and cost of preparing collections of new compounds in this class - a requirement of most modern drug discovery efforts - has been drastically reduced. "This is by far the most concise and flexible route to make a wide variety of novel steroids," said Micalizio. To show the value of the technology in biomedical science, the research team demonstrated that one of the molecules prepared in their initial study has potent and selective growth inhibitory properties against three different human cancer cell lines. "We're not just saying these things have potential," said Micalizio, "here is one example from the relatively small number of compounds that we produced that proves their potential value as anti-cancer agents." Since synthetic mirror image isomers are not readily available from natural sources, pursuit of this class of drugs and their clinical value is dependent on the efficiency with which organic chemists can prepare them. "The science of synthetic organic chemistry is an essential component of drug discovery, and advances in this field are directly responsible for our recent discovery," said Micalizio. "Without the ability to create new collections of molecules, it is difficult to pursue many potentially exciting new directions in drug discovery. As such, advances in chemical synthesis, like this one, can have profound and rippling effects on biomedical science," Micalizio added Building on the challenge to invent chemistry that fuels discovery in biomedical science, Micalizio's lab hopes to develop a new technology platform to explore unnatural isomers of steroids for the development of therapeutics. Founded in 1769, Dartmouth is a member of the Ivy League and offers the world's premier liberal arts education, combining its deep commitment to outstanding undergraduate and graduate teaching with distinguished research and scholarship in the arts and sciences and its three leading professional schools: the Geisel School of Medicine, Thayer School of Engineering and Tuck School of Business.

Parker A.S.,Dartmouth | Choi Y.,Dartmouth | Bailey-Kellogg C.,Dartmouth
PLoS Computational Biology | Year: 2015

The immunogenicity of biotherapeutics can bottleneck development pipelines and poses a barrier to widespread clinical application. As a result, there is a growing need for improved deimmunization technologies. We have recently described algorithms that simultaneously optimize proteins for both reduced T cell epitope content and high-level function. In silico analysis of this dual objective design space reveals that there is no single global optimum with respect to protein deimmunization. Instead, mutagenic epitope deletion yields a spectrum of designs that exhibit tradeoffs between immunogenic potential and molecular function. The leading edge of this design space is the Pareto frontier, i.e. the undominated variants for which no other single design exhibits better performance in both criteria. Here, the Pareto frontier of a therapeutic enzyme has been designed, constructed, and evaluated experimentally. Various measures of protein performance were found to map a functional sequence space that correlated well with computational predictions. These results represent the first systematic and rigorous assessment of the functional penalty that must be paid for pursuing progressively more deimmunized biotherapeutic candidates. Given this capacity to rapidly assess and design for tradeoffs between protein immunogenicity and functionality, these algorithms may prove useful in augmenting, accelerating, and de-risking experimental deimmunization efforts. © 2015 Salvat et al.

Georgakopoulos A.,University of Warwick | Winkler P.,Dartmouth
Combinatorics Probability and Computing | Year: 2014

We show that the expected time for a random walk on a (multi-)graph G to traverse all m edges of G, and return to its starting point, is at most 2m 2; if each edge must be traversed in both directions, the bound is 3m 2. Both bounds are tight and may be applied to graphs with arbitrary edge lengths. This has interesting implications for Brownian motion on certain metric spaces, including some fractals. © Cambridge University Press 2014.

Barghi A.,Bard College | Winkler P.,Dartmouth
Random Structures and Algorithms | Year: 2015

LetGλ be the graph whose vertices are points of a planar Poisson process of density λ, with vertices adjacent if they are within distance 1. A "fire" begins at some vertex and spreads to all neighbors in discrete steps; in the meantime f vertices can be deleted at each time-step. Let fλ be the least f such that, with probability 1, any fire on Gλ can be stopped in finite time. We show that fλ is bounded between two linear functions of λ. The lower bound makes use of a new result concerning oriented percolation in the plane; the constant factor in the upper bound is is tight, provided a certain conjecture, for which we offer supporting evidence, is correct. © 2013 Wiley Periodicals, Inc.

Mokhatab S.,Dartmouth | Corso S.,Comelt S.p.A.
Chemical Engineering (United States) | Year: 2016

Ongoing advances in both adsorbent materials and system engineering allow today's pressure swing adsorption (PSA) systems to produce nitrogen of varying purities and volumes at relatively low cost compared to cryogenic air separation.

Svitkina Z.,Google | Fleischer L.,Dartmouth
SIAM Journal on Computing | Year: 2011

We introduce several generalizations of classical computer science problems obtained by replacing simpler objective functions with general submodular functions. The new problems include submodular load balancing, which generalizes load balancing or minimum-makespan scheduling, submodular sparsest cut and submodular balanced cut, which generalize their respective graph cut problems, as well as submodular function minimization with a cardinality lower bound. We establish upper and lower bounds for the approximability of these problems with a polynomial number of queries to a function-value oracle. The approximation guarantees that most of our algorithms achieve are of the order of √n/ln n. We show that this is the inherent difficulty of the problems by proving matching lower bounds. We also give an improved lower bound for the problem of approximating a monotone submodular function everywhere. In addition, we present an algorithm for approximating submodular functions with a special structure, whose guarantee is close to the lower bound. Although quite restrictive, the class of functions with this structure includes the ones that are used for lower bounds both by us and in previous work. © 2011 Society for Industrial and Applied Mathematics.

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