13,656 research outputs found

    The Full Re-Ionization of Helium

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    Observations of resolved HeII Lyman alpha absorption in spectra of two QSO's suggest that the epoch of helium ionization occurred at z~3. Proximity zones in the spectra of the quasars (z=3.18, 3.285) at 304 A resemble Stromgren spheres, suggesting that the intergalactic medium is only singly ionized in helium. We present models of the proximity effect which include the full physics of the ionization, heating and cooling and an accurately simulated inhomogeneous gas distribution. In these models the underdense intergalactic medium is heated to at least 10,000-20,000 K after cooling to as low as a few 1000 K due to cosmological expansion, with higher temperatures achieved farther away from the quasar due to absorption-hardened ionizing spectra. The quasars turn on for a few times 10^7 years with a fairly steady flux output at 228 A comparable to the 304 A flux output directly observed with HST. The recoveries in the spectra occur naturally due to voids in the IGM and may provide a fairly model-independent probe of the baryon density.Comment: 5 pages, 3 figures, to appear in the proceedings of "After the Dark Ages: When Galaxies were Young (the Universe at 2<z<5)", 9th Annual October Astrophysics Conference in Marylan

    New Extension Approaches to Serving Agricultural Media in Advancing Farm-Life Safety Communications

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    The study described here focused on needs and opportunities for Extension to serve agricultural media more fully in addressing new safety risks in agriculture, one of the nation\u27s most hazardous industries. The study was conducted in the context of major broadening of channels used by agricultural media. A mixed-methods approach included a national survey to identify views and suggestions from agricultural journalists about covering farm-life safety. A companion literature review addressed case studies and other research featuring Extension collaborations with media for advancing farm-life safety. Findings revealed expanding opportunities and ideas for Extension personnel, with implications for Extension program areas beyond farm-life safety

    The DUB/USP17 deubiquitinating enzymes: A gene family within a tandemly repeated sequence, is also embedded within the copy number variable Beta-defensin cluster

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    <p>Abstract</p> <p>Background</p> <p>The DUB/USP17 subfamily of deubiquitinating enzymes were originally identified as immediate early genes induced in response to cytokine stimulation in mice (DUB-1, DUB-1A, DUB-2, DUB-2A). Subsequently we have identified a number of human family members and shown that one of these (DUB-3) is also cytokine inducible. We originally showed that constitutive expression of DUB-3 can block cell proliferation and more recently we have demonstrated that this is due to its regulation of the ubiquitination and activity of the 'CAAX' box protease RCE1.</p> <p>Results</p> <p>Here we demonstrate that the human DUB/USP17 family members are found on both chromosome 4p16.1, within a block of tandem repeats, and on chromosome 8p23.1, embedded within the copy number variable beta-defensin cluster. In addition, we show that the multiple genes observed in humans and other distantly related mammals have arisen due to the independent expansion of an ancestral sequence within each species. However, it is also apparent when sequences from humans and the more closely related chimpanzee are compared, that duplication events have taken place prior to these species separating.</p> <p>Conclusions</p> <p>The observation that the DUB/USP17 genes, which can influence cell growth and survival, have evolved from an unstable ancestral sequence which has undergone multiple and varied duplications in the species examined marks this as a unique family. In addition, their presence within the beta-defensin repeat raises the question whether they may contribute to the influence of this repeat on immune related conditions.</p

    Direct and indirect measurements on electrocaloric effect : recent developments and perspectives

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    Y.L. and B.D. acknowledge the China Scholarship Council (CSC) for funding Y.L.'s stay in France and a public grant overseen by the French National Research Agency (ANR) as part of the “Investissements d'Avenir” program (Reference: ANR-10-LABX-0035, Labex NanoSaclay).It has been ten years since the discovery of the giant electrocaloric effect in ferroelectric materials showed that it is possible to employ this effect for substantial cooling applications. This last decade has been marked by increasing research interest, especially in characterizing and measuring the electrocaloric effect using both the so-called indirect and direct approaches. In this context, a comprehensive summary and careful reexamination of these approaches are very timely and of great importance to justify the assumptions used in different measurement techniques. This review is therefore dedicated to cover recent important and rapid advances from both the indirect and direct measurements and provides critical insights relevant for quantifying the electrocaloric effect. It involves electrocaloric materials from normal ferroelectrics, antiferroelectrics, and relaxors, and it fundamentally focuses on how the electrocaloric entropy changes in response to electric field in these typical electrocalorics. The article addresses recent developments, especially during the past three years, such as technical selection of proper polarization-electric field loops, negative electrocaloric effect in antiferroelectrics and relaxors, the controversial debate on the indirect method in relaxors, the important role of field dependence of specific heat, kinetic factors, and so on. Moreover, this review also is concerned with extracting reliable data by direct measurements. Four typical techniques and devices used recently, such as thermocouples, differential scanning calorimeters, specifically designed calorimeters, and scanning thermal microscopy, are briefly reviewed, while infrared cameras are emphasized. We hope that our review will not only provide a useful background to understand fundamentally the electrocaloric effect and what one really measures but also may act as a practical guide to exploit and develop electrocalorics towards the design of suitable devices.Publisher PDFPeer reviewe

    Registration of N614, A3N615, N616, and N617 Shattercane Genetic Stocks with Cytoplasmic or Nuclear Male Sterility and Juicy or Dry Midribs

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    Four shattercane [Sorghum bicolor subsp. drummondii (Nees ex Steud.) de Wet ex Davidse] genetic stocks—N614 (Reg. No. GS-652, PI 665684), A3N615 (Reg. No. GS-651, PI 665683), N616 (Reg. No. GS-653, PI 665685), and N617 (Reg. No. GS-654, PI 665686)—with A3 cytoplasmic male sterility or the nuclear male sterility gene ms3 containing either juicy (dd) or dry (DD) culms were developed jointly by the USDA-ARS; the Iowa Agricultural and Home Economics Experiment Station, College of Agriculture and Life Sciences, Iowa State University; and the Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska. The stocks were released in July 2011. The source material for these genetic stocks was isolated from an archetypical shattercane population found near Lincoln, NE. Release of these genetic stocks makes available shattercane lines with both A3 cytoplasmic male sterility, and ms3 genetic (nuclear) male sterility to facilitate crossing. These genetic stocks also contain juicy (dd) or dry (DD) culms, a visible genetic marker to facilitate screening progeny resulting from crosses. The genetic stocks have immediate application for basic research involving gene flow from cultivated sorghum [Sorghum bicolor (L.) Moench] to shattercane and on the fitness of offspring resulting from such crosses

    Some strategies for improving caloric responses with ferroelectrics

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    Y.L. and B.D. acknowledge the China Scholarship Council (CSC) for funding Y.L.’s stay in France and a public grant overseen by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” program (Reference No. ANR-10-LABX-0035, Labex NanoSaclay).Many important breakthroughs and significant engineering developments have been achieved during the past two decades in the field of caloric materials. In this review, we address ferroelectrics emerging as ideal materials which permit both giant elastocaloric and/or electrocaloric responses near room temperature. We summarize recent strategies for improving caloric responses using geometrical optimization, maximizing the number of coexisting phases, combining positive and negative caloric responses, introducing extra degree of freedom like mechanical stress/pressure, and multicaloric effect driven by either single stimulus or multiple stimuli. This review highlights the promising perspective of ferroelectrics for developing next-generation solid-state refrigeration.Publisher PDFPeer reviewe

    Park Forest African American Pioneers: When and How We Entered, 1958-1968

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    The information contained in this presentation are copies of original documents and is based on information obtained from historical files of the Village of Park Forest, documents in the Park Forest [Public] Library and private citizens. This packet was produced with the help of Park Forest Historical Society Archivist Jane Nicoll in preparation for a program in February 1999 as a part of the 50th Anniversary of Park Forest. The original copy is located at the Park Forest Public Library, Park Forest Illinois, Ref 977.31 SCO Local History. Contents of Park Forest African American Pioneers, When and How we Entered 1958-1968 are: 1. Negroes in Residence in Park Forest as of January 1, 1969-By Street. This includes the date these families moved in (p. 4) 2. Policy on Minority Group Residence Adopted September 25, 1959. [which was unanimously adopted by the Commission on Human Relations at its September 1959 meeting.] (p. 13) 3. First Park Forest African American Co-op Residents, List from (Feb. 1964-1968). Includes some memos to Human Relations Commission. (p. 20) 4. (Section cover labeled: Federal Laws Affecting Housing) Fair Housing Ordinance, Village of Park Forest (Illinois), approved 1-29-1968. References 1963 Executive Order to affirmatively market VA and FHA Foreclosures, and 1964 Civil Rights Act. (p. 29) 5. Hello Dr. Wilson: Integration Comes to Park Forest. (December, 1959) (p. 33) 6. First Park Forest African-American Homeowners. A retyped list of the Negroes in Residence list. Includes memos and letters between Human Relation Commission Members, as a sample of what information was shared about new African American residents. (p. 38) 7. Human Relations Commission 1953. Includes a letter from John L. Scott, Village Manager about an incident in July 1959 when there was a rumored home sale to a Negro and memos from John Scott, Village Manager and Robert A. Dinerstein on how Village Employees should respond to the first Negro resident, which followed that incident later in July 1959. (p. 50) 8. William Simpson, Pioneer Resident and Community Activist. Mr. Simpson for years objected to and protested Integration Maintenance. (p. 58
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