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Showing papers by "Pennsylvania State University published in 2013"


Journal ArticleDOI
TL;DR: In this paper, a systematic approach to new concept development and grounded theory articulation that is designed to bring "qualitative rigor" to the conduct and presentation of inductive research is presented.
Abstract: For all its richness and potential for discovery, qualitative research has been critiqued as too often lacking in scholarly rigor. The authors summarize a systematic approach to new concept development and grounded theory articulation that is designed to bring “qualitative rigor” to the conduct and presentation of inductive research.

6,189 citations


Journal ArticleDOI
TL;DR: The 2017-18 FAHA/FACC/FAHA Education and Research Grants will be focused on advancing the profession’s understanding of central nervous system disorders and the management of post-traumatic stress disorder.

4,556 citations


Journal ArticleDOI
26 Mar 2013-ACS Nano
TL;DR: The properties and advantages of single-, few-, and many-layer 2D materials in field-effect transistors, spin- and valley-tronics, thermoelectrics, and topological insulators, among many other applications are highlighted.
Abstract: Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

4,123 citations



Journal ArticleDOI
TL;DR: The catalytically active Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.
Abstract: Nanoparticles of nickel phosphide (Ni2P) have been investigated for electrocatalytic activity and stability for the hydrogen evolution reaction (HER) in acidic solutions, under which proton exchange membrane-based electrolysis is operational. The catalytically active Ni2P nanoparticles were hollow and faceted to expose a high density of the Ni2P(001) surface, which has previously been predicted based on theory to be an active HER catalyst. The Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.

2,441 citations


Journal ArticleDOI
Fiona A. Harrison1, William W. Craig2, William W. Craig3, Finn Erland Christensen4, Charles J. Hailey5, William W. Zhang6, Steven E. Boggs3, Daniel Stern1, W. Rick Cook1, Karl Forster1, Paolo Giommi, Brian W. Grefenstette1, Yunjin Kim1, Takao Kitaguchi7, Jason E. Koglin5, Kristin K. Madsen1, Peter H. Mao1, Hiromasa Miyasaka1, Kaya Mori5, M. Perri8, Michael J. Pivovaroff2, Simonetta Puccetti8, Vikram Rana1, Niels Jørgen Stenfeldt Westergaard4, J. L. Willis1, Andreas Zoglauer3, Hongjun An9, Matteo Bachetti10, Matteo Bachetti11, Nicolas M. Barrière3, Eric C. Bellm1, Varun Bhalerao1, Varun Bhalerao12, Nicolai Brejnholt4, Felix Fuerst1, Carl Christian Liebe1, Craig B. Markwardt6, Melania Nynka5, Julia Vogel2, Dominic J. Walton1, Daniel R. Wik6, David M. Alexander13, L. R. Cominsky14, Ann Hornschemeier6, Allan Hornstrup4, Victoria M. Kaspi9, Greg Madejski, Giorgio Matt15, S. Molendi7, David M. Smith16, John A. Tomsick3, Marco Ajello3, David R. Ballantyne17, Mislav Baloković1, Didier Barret10, Didier Barret11, Franz E. Bauer18, Roger Blandford8, W. Niel Brandt19, Laura Brenneman20, James Chiang8, Deepto Chakrabarty21, Jérôme Chenevez4, Andrea Comastri7, Francois Dufour9, Martin Elvis20, Andrew C. Fabian22, Duncan Farrah23, Chris L. Fryer24, Eric V. Gotthelf5, Jonathan E. Grindlay20, D. J. Helfand25, Roman Krivonos3, David L. Meier1, Jon M. Miller26, Lorenzo Natalucci7, Patrick Ogle1, Eran O. Ofek27, Andrew Ptak6, Stephen P. Reynolds28, Jane R. Rigby6, Gianpiero Tagliaferri7, Stephen E. Thorsett29, Ezequiel Treister30, C. Megan Urry31 
TL;DR: The Nuclear Spectroscopic Telescope Array (NuSTAR) as discussed by the authors is the first focusing high-energy X-ray telescope in orbit, which operates in the band from 3 to 79 keV.
Abstract: The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 to 79 keV, extending the sensitivity of focusing far beyond the ~10 keV high-energy cutoff achieved by all previous X-ray satellites. The inherently low background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than 100-fold improvement in sensitivity over the collimated or coded mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity and spatial and spectral resolution, NuSTAR will pursue five primary scientific objectives: (1) probe obscured active galactic nucleus (AGN) activity out to the peak epoch of galaxy assembly in the universe (at z ≾ 2) by surveying selected regions of the sky; (2) study the population of hard X-ray-emitting compact objects in the Galaxy by mapping the central regions of the Milky Way; (3) study the non-thermal radiation in young supernova remnants, both the hard X-ray continuum and the emission from the radioactive element ^(44)Ti; (4) observe blazars contemporaneously with ground-based radio, optical, and TeV telescopes, as well as with Fermi and Swift, to constrain the structure of AGN jets; and (5) observe line and continuum emission from core-collapse supernovae in the Local Group, and from nearby Type Ia events, to constrain explosion models. During its baseline two-year mission, NuSTAR will also undertake a broad program of targeted observations. The observatory consists of two co-aligned grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis stabilized spacecraft. Deployed into a 600 km, near-circular, 6° inclination orbit, the observatory has now completed commissioning, and is performing consistent with pre-launch expectations. NuSTAR is now executing its primary science mission, and with an expected orbit lifetime of 10 yr, we anticipate proposing a guest investigator program, to begin in late 2014.

1,966 citations


Journal ArticleDOI
TL;DR: The Baryon Oscillation Spectroscopic Survey (BOSS) as discussed by the authors was designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure.
Abstract: The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg2 to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Lyα forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Lyα forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance dA to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Lyα forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate DA (z) and H –1(z) parameters to an accuracy of 1.9% at z ~ 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS.

1,938 citations



Journal ArticleDOI
TL;DR: Providing a future energy supply that is secure and CO_2-neutral will require switching to nonfossil energy sources such as wind, solar, nuclear, and geothermal energy and developing methods for transforming the energy produced by these new sources into forms that can be stored, transported, and used upon demand.
Abstract: Two major energy-related problems confront the world in the next 50 years. First, increased worldwide competition for gradually depleting fossil fuel reserves (derived from past photosynthesis) will lead to higher costs, both monetarily and politically. Second, atmospheric CO_2 levels are at their highest recorded level since records began. Further increases are predicted to produce large and uncontrollable impacts on the world climate. These projected impacts extend beyond climate to ocean acidification, because the ocean is a major sink for atmospheric CO2.1 Providing a future energy supply that is secure and CO_2-neutral will require switching to nonfossil energy sources such as wind, solar, nuclear, and geothermal energy and developing methods for transforming the energy produced by these new sources into forms that can be stored, transported, and used upon demand.

1,651 citations


Journal ArticleDOI
TL;DR: In this article, an updated 1D radiative-convective, cloud-free climate model is used to obtain new estimates for HZ widths around F, G, K, and M stars.
Abstract: Identifying terrestrial planets in the habitable zones (HZs) of other stars is one of the primary goals of ongoing radial velocity (RV) and transit exoplanet surveys and proposed future space missions. Most current estimates of the boundaries of the HZ are based on one-dimensional (1D), cloud-free, climate model calculations by Kasting et?al. However, this model used band models that were based on older HITRAN and HITEMP line-by-line databases. The inner edge of the HZ in the Kasting et?al. model was determined by loss of water, and the outer edge was determined by the maximum greenhouse provided by a CO2 atmosphere. A conservative estimate for the width of the HZ from this model in our solar system is 0.95-1.67?AU. Here an updated 1D radiative-convective, cloud-free climate model is used to obtain new estimates for HZ widths around F, G, K, and M stars. New H2O and CO2 absorption coefficients, derived from the HITRAN 2008 and HITEMP 2010 line-by-line databases, are important improvements to the climate model. According to the new model, the water-loss (inner HZ) and maximum greenhouse (outer HZ) limits for our solar system are at 0.99 and 1.70?AU, respectively, suggesting that the present Earth lies near the inner edge. Additional calculations are performed for stars with effective temperatures between 2600 and 7200?K, and the results are presented in parametric form, making them easy to apply to actual stars. The new model indicates that, near the inner edge of the HZ, there is no clear distinction between runaway greenhouse and water-loss limits for stars with T eff 5000?K, which has implications for ongoing planet searches around K and M stars. To assess the potential habitability of extrasolar terrestrial planets, we propose using stellar flux incident on a planet rather than equilibrium temperature. This removes the dependence on planetary (Bond) albedo, which varies depending on the host star's spectral type. We suggest that conservative estimates of the HZ (water-loss and maximum greenhouse limits) should be used for current RV surveys and Kepler mission to obtain a lower limit on ??, so that future flagship missions like TPF-C and Darwin are not undersized. Our model does not include the radiative effects of clouds; thus, the actual HZ boundaries may extend further in both directions than the estimates just given.

1,526 citations


Journal ArticleDOI
M. G. Aartsen1, Rasha Abbasi2, Y. Abdou3, Markus Ackermann, Jenni Adams4, Juanan Aguilar5, Markus Ahlers2, D. Altmann6, J. Auffenberg2, X. Bai, Michael J. Baker2, S. W. Barwick7, V. Baum8, R. C. Bay9, J. J. Beatty10, S. Bechet11, J. Becker Tjus12, K.-H. Becker13, M. L. Benabderrahmane, Segev BenZvi2, P. Berghaus, D. Berley14, Elisa Bernardini, A. Bernhard, D. Bertrand11, D. Z. Besson15, Gary Binder16, Gary Binder9, Daniel Bindig13, M. Bissok17, E. Blaufuss14, J. Blumenthal17, D. J. Boersma18, S. Bohaichuk19, C. Bohm20, D. Bose21, S. Böser22, Olga Botner18, L. Brayeur21, H.-P. Bretz, A. M. Brown4, R. Bruijn23, Jürgen Brunner, M. J. Carson3, J. Casey24, M. Casier21, Dmitry Chirkin2, A. Christov5, B. Christy14, K. Clark25, F. Clevermann26, S. Coenders17, Seth M. Cohen23, D. F. Cowen25, A. H. Cruz Silva, M. Danninger20, J. Daughhetee24, J. C. Davis10, M. Day2, C. De Clercq21, S. De Ridder3, Paolo Desiati2, K. D. de Vries21, Tyce DeYoung25, Juan Carlos Diaz-Velez2, Matt Dunkman25, R. Eagan25, B. Eberhardt8, B. Eichmann12, J. Eisch2, R. W. Ellsworth14, S. Euler17, Paul Evenson, O. Fadiran2, A. R. Fazely27, Anatoli Fedynitch12, J. Feintzeig2, T. Feusels3, Kirill Filimonov9, Chad Finley20, T. Fischer-Wasels13, S. Flis20, A. Franckowiak22, K. Frantzen26, T. Fuchs26, Thomas K. Gaisser, J. C. Gallagher2, L. Gerhardt9, L. Gerhardt16, L. Gladstone2, Thorsten Glusenkamp, A. Goldschmidt16, G. Golup21, J. G. Gonzalez, J. A. Goodman14, Dariusz Gora, Dylan T. Grandmont19 
20 Nov 2013-Science
TL;DR: The presence of a high-energy neutrino flux containing the most energetic neutrinos ever observed is revealed, including 28 events at energies between 30 and 1200 TeV, although the origin of this flux is unknown and the findings are consistent with expectations for a neutRino population with origins outside the solar system.
Abstract: We report on results of an all-sky search for high-energy neutrino events interacting within the IceCube neutrino detector conducted between May 2010 and May 2012. The search follows up on the previous detection of two PeV neutrino events, with improved sensitivity and extended energy coverage down to about 30 TeV. Twenty-six additional events were observed, substantially more than expected from atmospheric backgrounds. Combined, both searches reject a purely atmospheric origin for the 28 events at the 4 sigma level. These 28 events, which include the highest energy neutrinos ever observed, have flavors, directions, and energies inconsistent with those expected from the atmospheric muon and neutrino backgrounds. These properties are, however, consistent with generic predictions for an additional component of extraterrestrial origin.

Journal ArticleDOI
TL;DR: Evaluation of women with PCOS should exclude alternate androgen-excess disorders and risk factors for endometrial cancer, mood disorders, obstructive sleep apnea, diabetes, and cardiovascular disease.
Abstract: Objective: The aim was to formulate practice guidelines for the diagnosis and treatment of polycystic ovary syndrome (PCOS). Participants: An Endocrine Society-appointed Task Force of experts, a methodologist, and a medical writer developed the guideline. Evidence: This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. Consensus Process: One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of The Endocrine Society and the European Society of Endocrinology reviewed and commented on preliminary drafts of these guidelines. Two systematic reviews were conducted to summarize supporting evidence. Conclusions: We suggest using the Rotterdam criteria for diagnosing PCOS (presence of two of the following criteria: androgen excess, ovulatory dysfunction, or polycystic ovaries). Establishing a diagno...

Journal ArticleDOI
TL;DR: The direct synthesis of WS2 monolayers with triangular morphologies and strong room-temperature photoluminescence (PL) is described and the structure and chemical composition of the platelet edges appear to be critical for PL enhancement.
Abstract: Individual monolayers of metal dichalcogenides are atomically thin two-dimensional crystals with attractive physical properties different from those of their bulk counterparts. Here we describe the direct synthesis of WS2 monolayers with triangular morphologies and strong room-temperature photoluminescence (PL). The Raman response as well as the luminescence as a function of the number of S–W–S layers is also reported. The PL weakens with increasing number of layers due to a transition from direct band gap in a monolayer to indirect gap in multilayers. The edges of WS2 monolayers exhibit PL signals with extraordinary intensity, around 25 times stronger than that at the platelet’s center. The structure and chemical composition of the platelet edges appear to be critical for PL enhancement.

Journal ArticleDOI
Natalie M. Batalha1, Natalie M. Batalha2, Jason F. Rowe2, Stephen T. Bryson2, Thomas Barclay2, Christopher J. Burke2, Douglas A. Caldwell2, Jessie L. Christiansen2, Fergal Mullally2, Susan E. Thompson2, Timothy M. Brown3, Andrea K. Dupree4, Daniel C. Fabrycky5, Eric B. Ford6, Jonathan J. Fortney5, Ronald L. Gilliland7, Howard Isaacson8, David W. Latham4, Geoffrey W. Marcy8, Samuel N. Quinn4, Samuel N. Quinn9, Darin Ragozzine4, Avi Shporer3, William J. Borucki2, David R. Ciardi10, Thomas N. Gautier10, Michael R. Haas2, Jon M. Jenkins2, David G. Koch2, Jack J. Lissauer2, William Rapin2, Gibor Basri8, Alan P. Boss11, Lars A. Buchhave12, Joshua A. Carter4, David Charbonneau4, Joergen Christensen-Dalsgaard13, Bruce D. Clarke10, William D. Cochran14, Brice-Olivier Demory15, Jean-Michel Desert4, Edna DeVore16, Laurance R. Doyle16, Gilbert A. Esquerdo4, Mark E. Everett, Francois Fressin4, John C. Geary4, Forrest R. Girouard2, Alan Gould17, Jennifer R. Hall2, Matthew J. Holman4, Andrew W. Howard8, Steve B. Howell2, Khadeejah A. Ibrahim2, Karen Kinemuchi2, Hans Kjeldsen13, Todd C. Klaus2, Jie Li2, Philip W. Lucas18, Søren Meibom4, Robert L. Morris2, Andrej Prsa19, Elisa V. Quintana2, Dwight T. Sanderfer2, Dimitar Sasselov4, Shawn Seader2, Jeffrey C. Smith2, Jason H. Steffen20, Martin Still2, Martin C. Stumpe2, Jill Tarter16, Peter Tenenbaum2, Guillermo Torres4, Joseph D. Twicken2, Kamal Uddin2, Jeffrey Van Cleve2, Lucianne M. Walkowicz21, William F. Welsh22 
TL;DR: In this paper, the authors verified nearly 5000 periodic transit-like signals against astrophysical and instrumental false positives yielding 1108 viable new transiting planet candidates, bringing the total count up to over 2300.
Abstract: New transiting planet candidates are identified in 16 months (2009 May-2010 September) of data from the Kepler spacecraft. Nearly 5000 periodic transit-like signals are vetted against astrophysical and instrumental false positives yielding 1108 viable new planet candidates, bringing the total count up to over 2300. Improved vetting metrics are employed, contributing to higher catalog reliability. Most notable is the noise-weighted robust averaging of multi-quarter photo-center offsets derived from difference image analysis that identifies likely background eclipsing binaries. Twenty-two months of photometry are used for the purpose of characterizing each of the candidates. Ephemerides (transit epoch, T_0, and orbital period, P) are tabulated as well as the products of light curve modeling: reduced radius (R_P/R_★), reduced semimajor axis (d/R_★), and impact parameter (b). The largest fractional increases are seen for the smallest planet candidates (201% for candidates smaller than 2 R_⊕ compared to 53% for candidates larger than 2 R_⊕) and those at longer orbital periods (124% for candidates outside of 50 day orbits versus 86% for candidates inside of 50 day orbits). The gains are larger than expected from increasing the observing window from 13 months (Quarters 1-5) to 16 months (Quarters 1-6) even in regions of parameter space where one would have expected the previous catalogs to be complete. Analyses of planet frequencies based on previous catalogs will be affected by such incompleteness. The fraction of all planet candidate host stars with multiple candidates has grown from 17% to 20%, and the paucity of short-period giant planets in multiple systems is still evident. The progression toward smaller planets at longer orbital periods with each new catalog release suggests that Earth-size planets in the habitable zone are forthcoming if, indeed, such planets are abundant.

Journal ArticleDOI
17 May 2013-Science
TL;DR: Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help effectively manage water-quality risks associated with unconventional gas industry today and in the future.
Abstract: Unconventional natural gas resources offer an opportunity to access a relatively clean fossil fuel that could potentially lead to energy independence for some countries. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. We review the current understanding of environmental issues associated with unconventional gas extraction. Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help manage these water-quality risks today and in the future.

Journal ArticleDOI
TL;DR: In this paper, the frequency of the A1g(Γ) phonon mode monotonically decreases with the number of layers and the excitation wavelength in the visible range (488, 514 and 647 nm).
Abstract: The Raman scattering of single- and few-layered WS2 is studied as a function of the number of S-W-S layers and the excitation wavelength in the visible range (488, 514 and 647 nm). For the three excitation wavelengths used in this study, the frequency of the A1g(Γ) phonon mode monotonically decreases with the number of layers. For single-layer WS2, the 514.5 nm laser excitation generates a second-order Raman resonance involving the longitudinal acoustic mode (LA(M)). This resonance results from a coupling between the electronic band structure and lattice vibrations. First-principles calculations were used to determine the electronic and phonon band structures of single-layer and bulk WS2. The reduced intensity of the 2LA mode was then computed, as a function of the laser wavelength, from the fourth-order Fermi golden rule. Our observations establish an unambiguous and nondestructive Raman fingerprint for identifying single- and few-layered WS2 films.

Journal ArticleDOI
TL;DR: In this article, the role and use of social media in travelers' decision-making and in tourism operations and management have been widely discussed in tourism and hospitality research, and the authors reviewed and analyzed all extant social media-related research articles published in academic journals during 2007 to 2011.
Abstract: Being one of the “mega trends” that has significantly impacted the tourism system, the role and use of social media in travelers' decision making and in tourism operations and management have been widely discussed in tourism and hospitality research. This study reviews and analyzes all extant social media-related research articles published in academic journals during 2007 to 2011, mainly in tourism and hospitality fields. Based on a content analysis on the analyzed articles from both the consumers' and the suppliers' perspectives, this article found that consumer-centric studies generally focused on the use and impact of social media in the research phase of the travelers' travel planning process. Supplier-related studies have concentrated closely on promotion, management, and research functions, but few discussed product distribution. Research findings thoroughly demonstrate the strategic importance of social media for tourism competitiveness. This study also contributes to the academia and ind...

Journal ArticleDOI
TL;DR: In this article, the design and performance of the multi-object fiber spectrographs for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon Oscillation Spectroscopic Survey (BOSS) were presented.
Abstract: We present the design and performance of the multi-object fiber spectrographs for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999 on the 2.5 m aperture Sloan Telescope at Apache Point Observatory, the spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II surveys, enabling a wide variety of Galactic and extra-galactic science including the first observation of baryon acoustic oscillations in 2005. The spectrographs were upgraded in 2009 and are currently in use for BOSS, the flagship survey of the third-generation SDSS-III project. BOSS will measure redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyα absorption of 160,000 high redshift quasars over 10,000 deg2 of sky, making percent level measurements of the absolute cosmic distance scale of the universe and placing tight constraints on the equation of state of dark energy. The twin multi-object fiber spectrographs utilize a simple optical layout with reflective collimators, gratings, all-refractive cameras, and state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in two channels over a bandpass covering the near-ultraviolet to the near-infrared, with a resolving power R = λ/FWHM ~ 2000. Building on proven heritage, the spectrographs were upgraded for BOSS with volume-phase holographic gratings and modern CCD detectors, improving the peak throughput by nearly a factor of two, extending the bandpass to cover 360 nm < λ < 1000 nm, and increasing the number of fibers from 640 to 1000 per exposure. In this paper we describe the original SDSS spectrograph design and the upgrades implemented for BOSS, and document the predicted and measured performances.

Journal ArticleDOI
TL;DR: These 10-year results show that induction PF followed by RT and concomitant cisplatin/RT show similar efficacy for the composite end point of LFS, and new strategies that improve organ preservation and function with less morbidity are needed.
Abstract: Purpose To report the long-term results of the Intergroup Radiation Therapy Oncology Group 91-11 study evaluating the contribution of chemotherapy added to radiation therapy (RT) for larynx preservation. Patients and Methods Patients with stage III or IV glottic or supraglottic squamous cell cancer were randomly assigned to induction cisplatin/fluorouracil (PF) followed by RT (control arm), concomitant cisplatin/RT, or RT alone. The composite end point of laryngectomy-free survival (LFS) was the primary end point. Results Five hundred twenty patients were analyzed. Median follow-up for surviving patients is 10.8 years. Both chemotherapy regimens significantly improved LFS compared with RT alone (induction chemotherapy v RT alone: hazard ratio [HR], 0.75; 95% CI, 0.59 to 0.95; P = .02; concomitant chemotherapy v RT alone: HR, 0.78; 95% CI, 0.78 to 0.98; P = .03). Overall survival did not differ significantly, although there was a possibility of worse outcome with concomitant relative to induction chemother...

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TL;DR: In this article, a hypothetical ideotype is presented to optimize water and N acquisition by maize root systems, based on the coincidence of root foraging and resource availability in time and space.

Journal ArticleDOI
TL;DR: The proposed method optimizes the shape of the supercell jointly with the occupation of the atomic sites, thus ensuring that the configurational space searched is exhaustive and not biased by a pre-specified supercell shape.
Abstract: We present a new algorithm to generate Special Quasirandom Structures (SQS), i.e., best periodic supercell approximations to the true disordered state for a given number of atoms per supercell. The method is based on a Monte Carlo simulated annealing loop with an objective function that seeks to perfectly match the maximum number of correlation functions (as opposed to merely minimizing the distance between the SQS correlation and the disordered state correlations for a pre-specified set of correlations). The proposed method optimizes the shape of the supercell jointly with the occupation of the atomic sites, thus ensuring that the configurational space searched is exhaustive and not biased by a pre-specified supercell shape. The method has been implemented in the “mcsqs” code of the Alloy Theoretic Automated Toolkit (ATAT) in the most general framework of multicomponent multisublattice systems and in a way that minimizes the amount of input information the user needs to specify and that allows for efficient parallelization.

Journal ArticleDOI
TL;DR: The first large-scale application of the phenome-wide association study (PheWAS) paradigm within electronic medical records (EMRs) is reported, an unbiased approach to replication and discovery that interrogates relationships between targeted genotypes and multiple phenotypes in EMR-based cohorts.
Abstract: Candidate gene and genome-wide association studies (GWAS) have identified genetic variants that modulate risk for human disease; many of these associations require further study to replicate the results. Here we report the first large-scale application of the phenome-wide association study (PheWAS) paradigm within electronic medical records (EMRs), an unbiased approach to replication and discovery that interrogates relationships between targeted genotypes and multiple phenotypes. We scanned for associations between 3,144 single-nucleotide polymorphisms (previously implicated by GWAS as mediators of human traits) and 1,358 EMR-derived phenotypes in 13,835 individuals of European ancestry. This PheWAS replicated 66% (51/77) of sufficiently powered prior GWAS associations and revealed 63 potentially pleiotropic associations with P < 4.6 × 10⁻⁶ (false discovery rate < 0.1); the strongest of these novel associations were replicated in an independent cohort (n = 7,406). These findings validate PheWAS as a tool to allow unbiased interrogation across multiple phenotypes in EMR-based cohorts and to enhance analysis of the genomic basis of human disease.

Journal ArticleDOI
J. Aasi1, J. Abadie1, B. P. Abbott1, R. Abbott1  +745 moreInstitutions (73)
TL;DR: In this article, the authors inject squeezed states to improve the performance of one of the detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) beyond the quantum noise limit, most notably in the frequency region down to 150 Hz.
Abstract: Nearly a century after Einstein first predicted the existence of gravitational waves, a global network of Earth-based gravitational wave observatories1, 2, 3, 4 is seeking to directly detect this faint radiation using precision laser interferometry. Photon shot noise, due to the quantum nature of light, imposes a fundamental limit on the attometre-level sensitivity of the kilometre-scale Michelson interferometers deployed for this task. Here, we inject squeezed states to improve the performance of one of the detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) beyond the quantum noise limit, most notably in the frequency region down to 150 Hz, critically important for several astrophysical sources, with no deterioration of performance observed at any frequency. With the injection of squeezed states, this LIGO detector demonstrated the best broadband sensitivity to gravitational waves ever achieved, with important implications for observing the gravitational-wave Universe with unprecedented sensitivity.

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TL;DR: LCA provides a way to identify a small set of underlying subgroups characterized by multiple dimensions which could, in turn, be used to examine differential treatment effects, and can facilitate targeting future intervention resources to subgroups that promise to show the maximum treatment response.
Abstract: The overall goal of this study is to introduce latent class analysis (LCA) as an alternative approach to latent subgroup analysis. Traditionally, subgroup analysis aims to determine whether individuals respond differently to a treatment based on one or more measured characteristics. LCA provides a way to identify a small set of underlying subgroups characterized by multiple dimensions which could, in turn, be used to examine differential treatment effects. This approach can help to address methodological challenges that arise in subgroup analysis, including a high Type I error rate, low statistical power, and limitations in examining higher-order interactions. An empirical example draws on N = 1,900 adolescents from the National Longitudinal Survey of Adolescent Health. Six characteristics (household poverty, single-parent status, peer cigarette use, peer alcohol use, neighborhood unemployment, and neighborhood poverty) are used to identify five latent subgroups: Low Risk, Peer Risk, Economic Risk, Household & Peer Risk, and Multi-Contextual Risk. Two approaches for examining differential treatment effects are demonstrated using a simulated outcome: 1) a classify-analyze approach and, 2) a model-based approach based on a reparameterization of the LCA with covariates model. Such approaches can facilitate targeting future intervention resources to subgroups that promise to show the maximum treatment response.

Journal ArticleDOI
M. G. Aartsen1, Rasha Abbasi2, Y. Abdou3, Markus Ackermann  +284 moreInstitutions (36)
TL;DR: These two neutrino-induced events could be a first indication of an astrophysical neutrinos flux; the moderate significance, however, does not permit a definitive conclusion at this time.
Abstract: We report on the observation of two neutrino-induced events which have an estimated deposited energy in the IceCube detector of 1.04 +/- 0.16 and 1.14 +/- 0.17 PeV, respectively, the highest neutrino energies observed so far. These events are consistent with fully contained particle showers induced by neutral-current nu(e,mu,tau) ((nu) over bar (e,mu,tau)) or charged-current nu(e) ((nu) over bar (e)) interactions within the IceCube detector. The events were discovered in a search for ultrahigh energy neutrinos using data corresponding to 615.9 days effective live time. The expected number of atmospheric background is 0.082 +/- 0.004(stat)(-0.057)(+0.041)(syst). The probability of observing two or more candidate events under the atmospheric background-only hypothesis is 2.9 x 10(-3) (2.8 sigma) taking into account the uncertainty on the expected number of background events. These two events could be a first indication of an astrophysical neutrino flux; the moderate significance, however, does not permit a definitive conclusion at this time.

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TL;DR: Comparisons between the different classes of plant small RNAs help to illuminate key goals for future research.
Abstract: Regulatory small RNAs, which range in size from 20 to 24 nucleotides, are ubiquitous components of endogenous plant transcriptomes, as well as common responses to exogenous viral infections and introduced double-stranded RNA (dsRNA). Endogenous small RNAs derive from the processing of helical RNA precursors and can be categorized into several groups based on differences in biogenesis and function. A major distinction can be observed between small RNAs derived from singlestranded precursors with a hairpin structure [referred to here as hairpin RNAs (hpRNAs)] and those derived from dsRNA precursors [small interfering RNAs (siRNAs)]. hpRNAs in plants can be divided into two secondary groups: microRNAs and those that are not microRNAs. The currently known siRNAs fall mostly into one of three secondary groups: heterochromatic siRNAs, secondary siRNAs, and natural antisense transcript siRNAs. Tertiary subdivisions can be identified within many of the secondary classifications as well. Comparisons between the different classes of plant small RNAs help to illuminate key goals for future research.

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TL;DR: This review seeks to provide a balanced, coherent, and unified presentation of several distinct approaches for developing CG models, including top-down, network- based, native-centric, knowledge-based, and bottom-up modeling strategies.
Abstract: By focusing on essential features, while averaging over less important details, coarse-grained (CG) models provide significant computational and conceptual advantages with respect to more detailed models. Consequently, despite dramatic advances in computational methodologies and resources, CG models enjoy surging popularity and are becoming increasingly equal partners to atomically detailed models. This perspective surveys the rapidly developing landscape of CG models for biomolecular systems. In particular, this review seeks to provide a balanced, coherent, and unified presentation of several distinct approaches for developing CG models, including top-down, network-based, native-centric, knowledge-based, and bottom-up modeling strategies. The review summarizes their basic philosophies, theoretical foundations, typical applications, and recent developments. Additionally, the review identifies fundamental inter-relationships among the diverse approaches and discusses outstanding challenges in the field. When carefully applied and assessed, current CG models provide highly efficient means for investigating the biological consequences of basic physicochemical principles. Moreover, rigorous bottom-up approaches hold great promise for further improving the accuracy and scope of CG models for biomolecular systems.

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TL;DR: The theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended are discussed, and the SAW-enabled microfluidic devices demonstrated to date are reviewed.
Abstract: The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next.

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TL;DR: On the right path: Based on DFT calculations (incorporating the role of water solvation) of the activation barriers of elementary steps, a new path that leads to methane and ethylene for CO(2) electroreduction on Cu(111) was identified.
Abstract: On the right path: Based on DFT calculations (incorporating the role of water solvation) of the activation barriers of elementary steps, a new path that leads to methane and ethylene for CO(2) electroreduction on Cu(111) was identified. Methane formation proceeds through reduction of CO to COH (path II, see picture), which leads to CH(x) species that can produce both methane and ethylene, as observed experimentally.

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20 Dec 2013-Science
TL;DR: Genome structure and phylogenomic analyses indicate that the ancestral Angiosperm was a polyploid with a large constellation of both novel and ancient genes that survived to play key roles in angiosperm biology.
Abstract: Amborella trichopoda is strongly supported as the single living species of the sister lineage to all other extant flowering plants, providing a unique reference for inferring the genome content and structure of the most recent common ancestor (MRCA) of living angiosperms. Sequencing the Amborella genome, we identified an ancient genome duplication predating angiosperm diversification, without evidence of subsequent, lineage-specific genome duplications. Comparisons between Amborella and other angiosperms facilitated reconstruction of the ancestral angiosperm gene content and gene order in the MRCA of core eudicots. We identify new gene families, gene duplications, and floral protein-protein interactions that first appeared in the ancestral angiosperm. Transposable elements in Amborella are ancient and highly divergent, with no recent transposon radiations. Population genomic analysis across Amborella's native range in New Caledonia reveals a recent genetic bottleneck and geographic structure with conservation implications.