First-principles calculation of the temperature dependence of the optical response of bulk GaAs

A novel approach has been developed to calculate the temperature dependence of the optical response of a semiconductor. The dielectric function is averaged over several thermally perturbed configurations that are extracted from molecular dynamic simulations. The calculated temperature dependence of the imaginary part of the dielectric function of GaAs is presented in the range from 0 to 700 K. This approach that explicitly takes into account lattice vibrations describes well the observed thermally-induced energy shifts and broadening of the dielectric function.Comment: 6 pages, 3 figure

Comparative mitochondrial and chloroplast genomics of a genetically distinct form of Sargassum contributing to recent “Golden Tides” in the Western Atlantic

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ecology and Evolution 7 (2017): 516–525, doi:10.1002/ece3.2630.Over the past 5 years, massive accumulations of holopelagic species of the brown macroalga Sargassum in coastal areas of the Caribbean have created “golden tides” that threaten local biodiversity and trigger economic losses associated with beach deterioration and impact on fisheries and tourism. In 2015, the first report identifying the cause of these extreme events implicated a rare form of the holopelagic species Sargassum natans (form VIII). However, since the first mention of S. natans VIII in the 1930s, based solely on morphological characters, no molecular data have confirmed this identification. We generated full-length mitogenomes and partial chloroplast genomes of all representative holopelagic Sargassum species, S. fluitans III and S. natans I alongside the putatively rare S. natans VIII, to demonstrate small but consistent differences between S. natans I and VIII (7 bp differences out of the 34,727). Our comparative analyses also revealed that both S. natans I and S. natans VIII share a very close phylogenetic relationship with S. fluitans III (94- and 96-bp differences of 34,727). We designed novel primers that amplified regions of the cox2 and cox3 marker genes with consistent polymorphic sites that enabled differentiation between the two S. natans forms (I and VIII) from each other and both from S. fluitans III in over 150 Sargassum samples including those from the 2014 golden tide event. Despite remarkable gene synteny and sequence conservation, the three Sargassum forms differ in morphology, ecology, and distribution patterns, warranting more extensive interrogation of holopelagic Sargassum genomes as a whole.This work was supported by a US National Science Foundation (NSF) collaborative grant to LAA-Z (OCE-1155571) and ERZ (OCE-1155379), and an NSF TUES grant (DUE-1043468) to LAA-Z and ER

Envisioning a Marine Biodiversity Observation Network

Humans depend on diverse ocean ecosystems for food, jobs, and sustained well-being, yet many stressors threaten marine life. Extensive research has demonstrated that maintaining biodiversity promotes ocean health and service provision; therefore, monitoring the status and trends of marine biodiversity is important for effective ecosystem management. However, there is no systematic sustained program for evaluating ocean biodiversity. Coordinating existing monitoring and building a proactive marine biodiversity observation network will support efficient, economical resource management and conservation and should be a high priority. A synthesis of expert opinions suggests that, to be most effective, a marine biodiversity observation network should integrate biological levels, from genes to habitats; link biodiversity observations to abiotic environmental variables; site projects to incorporate environmental forcing and biogeography; and monitor adaptively to address emerging issues. We summarize examples illustrating how to leverage existing data and infrastructure to meet these goals

The role of interpersonal influence in counterbalancing psychopathic personality trait facets at work

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordThe purpose of this study was to examine the relations of two facets of psychopathic personality (i.e., self-centered impulsivity and fearless dominance) with interpersonally directed counterproductive work behavior (CWB-I) and contextual performance (CP). Consistent with research on psychopathy, our hypothesis suggested that self-centered impulsivity (i.e., behavioral impulsivity characterized by disregard for rules and responsibilities) would be positively related to CWB-I and negatively related to CP. Using socioanalytic theory, we further suggested that fearless dominance (i.e., an egotistical personal style characterized by self-promotion and prioritization of one’s own needs before those of others) would be negatively associated with interpersonal performance (i.e., high CWB-I and low CP) only when individuals indicated low levels of interpersonal influence (i.e., a dimension of political skill reflecting an ability to adapt one’s behavior in subtle, sophisticated, and situationally effective ways). Results provided strong support for the differential relations of the psychopathic personality dimensions with the criteria of interest. Implications for theory, practice, and future research are provided in light of a number of notable strengths and limitations

Prospectus, November 2, 1977

NEWS IN BRIEF: HIGH SCHOOLERS HERE, FACULTY WIVES GIVE SCHOLARSHIP, SHOPPING TRIP SET FOR DECEMBER 3RD, CHI DISCUSSION ON WEIGHT CONTROL; Parkland Events; Fireworks fly at Stu-Go meet; Letters to the editor: ORT\u27s explained, Pigeons praised; Pleas for PLATO: \u27a blessing for students\u27, \u27strongly urge retention, \u27have a heart\u27, \u27negative through waves\u27, \u27like throwing out books\u27; Louse epidemic in local schools; Advertising Policy; Peer pressure, low income cited: Blacks are still not college bound today; Scholar refutes Malthusian scientific racism theories; Area juvenile offenders get bigger breaks now; Bus Stop: a refreshing bit of American at Krannert; Women are arrested during clash between police and striking miners; Women sponsor child-rearing free workshop; Health Dept. probes cancer causing drug; Women\u27s balloon altitude mark set; United Airlines recruit engineers; Prizes, scholarships for film making students; Halloween Day: Every gorilla shall have his day; At Sullivan\u27s Little Theatre: Opening night of Vanities a delight; Tykociner \u2778 speaker selected; Pig heart valves are saving lives; A very good year: Oh, the passions for a \u2757 Chevrolet; Russian poet at UI; Open House; Ragtime rhythms exhilirate Caramia\u27s Krannert crowd; Classifieds; Conference leads split as football enters final weeks; Lincoln Trail wins jr. college gold tournament; Bring on Woody!! Illini loss is fooler; Women\u27s regional volleyball tourney here this weekend; Kraft Werk upsets IM football favorites, 12-0; Fast Freddy; A review: Air pockets mar new courtshttps://spark.parkland.edu/prospectus_1977/1006/thumbnail.jp

Absence of quantum-confined Stark effect in GaN quantum disks embedded in (Al,Ga)N nanowires grown by molecular beam epitaxy

Several of the key issues of planar (Al,Ga)N-based deep-ultraviolet light emitting diodes could potentially be overcome by utilizing nanowire heterostructures, exhibiting high structural perfection and improved light extraction. Here, we study the spontaneous emission of GaN/(Al,Ga)N nanowire ensembles grown on Si(111) by plasma-assisted molecular beam epitaxy. The nanowires contain single GaN quantum disks embedded in long (Al,Ga)N nanowire segments essential for efficient light extraction. These quantum disks are found to exhibit intense emission at unexpectedly high energies, namely, significantly above the GaN bandgap, and almost independent of the disk thickness. An in-depth investigation of the actual structure and composition of the nanowires reveals a spontaneously formed Al gradient both along and across the nanowire, resulting in a complex core/shell structure with an Al deficient core and an Al rich shell with continuously varying Al content along the entire length of the (Al,Ga)N segment. This compositional change along the nanowire growth axis induces a polarization doping of the shell that results in a degenerate electron gas in the disk, thus screening the built-in electric fields. The high carrier density not only results in the unexpectedly high transition energies, but also in radiative lifetimes depending only weakly on temperature, leading to a comparatively high internal quantum efficiency of the GaN quantum disks up to room temperature.Comment: This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Nano Letters (2019), copyright (C) American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/acs.nanolett.9b01521, the supporting information is available (free of charge) under the same lin

Envisioning a marine biodiversity observation network

Author Posting. © University of California Press and American Institute of Biological Sciences, 2013. This article is posted here by permission of University of California Press and American Institute of Biological Sciences for personal use, not for redistribution. The definitive version was published in BioScience 63 (2013): 350-361, doi:10.1525/bio.2013.63.5.8.Humans depend on diverse ocean ecosystems for food, jobs, and sustained well-being, yet many stressors threaten marine life. Extensive research has demonstrated that maintaining biodiversity promotes ocean health and service provision; therefore, monitoring the status and trends of marine biodiversity is important for effective ecosystem management. However, there is no systematic sustained program for evaluating ocean biodiversity. Coordinating existing monitoring and building a proactive marine biodiversity observation network will support efficient, economical resource management and conservation and should be a high priority. A synthesis of expert opinions suggests that, to be most effective, a marine biodiversity observation network should integrate biological levels, from genes to habitats; link biodiversity observations to abiotic environmental variables; site projects to incorporate environmental forcing and biogeography; and monitor adaptively to address emerging issues. We summarize examples illustrating how to leverage existing data and infrastructure to meet these goals