2,544 research outputs found

    The Radial Structure of the Cygnus Loop Supernova Remnant --- Possible evidence of a cavity explosion ---

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    We observed the North-East (NE) Limb toward the center region of the Cygnus Loop with the ASCA Observatory. We found a radial variation of electron temperature (kTe) and ionization timescale (log(\tau)) whereas no variation could be found for the abundances of heavy elements. In this paper, we re-analyzed the same data set and new observations with the latest calibration files. Then we constructed the precise spatial variations of kTe, log(\tau), and abundances of O, Ne, Mg, Si, and Fe over the field of view (FOV). We found a spatial variation not only in kTe and in log(\tau) but also in most of heavy elements. As described in Miyata et al. (1994), values of kTe increase and those of log(\tau) decrease toward the inner region. We found that the abundance of heavy elements increases toward the inner region. The radial profiles of O, Ne, and Fe show clear jump structures at a radius of 0.9 Rs, where Rs is the shock radius. Outside of 0.9 Rs, abundances of all elements are constant. On the contrary, inside of 0.9 Rs, abundances of these elements are 20--30 % larger than those obtained outside of 0.9 Rs. The radial profile of kTe also shows the jump structure at 0.9 Rs. This means that the hot and metal rich plasma fills the volume inside of 0.9 Rs. We concluded that this jump structure was the possible evidence for the pre-existing cavity produced by the precursor. If the ejecta fills inside of 0.9 Rs, the total mass of the ejecta was roughly 4\Msun. We then estimated the main-sequence mass to be roughly 15\Msun, which supports the massive star in origin of the Cygnus Loop supernova remnant and the existence of a pre-existing cavity.Comment: 37 pages, 14 figures. Accepted for publication of Ap

    Is the Sun Embedded in a Typical Interstellar Cloud?

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    The physical properties and kinematics of the partially ionized interstellar material near the Sun are typical of warm diffuse clouds in the solar vicinity. The interstellar magnetic field at the heliosphere and the kinematics of nearby clouds are naturally explained in terms of the S1 superbubble shell. The interstellar radiation field at the Sun appears to be harder than the field ionizing ambient diffuse gas, which may be a consequence of the low opacity of the tiny cloud surrounding the heliosphere. The spatial context of the Local Bubble is consistent with our location in the Orion spur.Comment: "From the Outer Heliosphere to the Local Bubble", held at International Space Sciences Institute, October 200

    Integrated HIV Testing, Malaria, and Diarrhea Prevention Campaign in Kenya: Modeled Health Impact and Cost-Effectiveness

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    Efficiently delivered interventions to reduce HIV, malaria, and diarrhea are essential to accelerating global health efforts. A 2008 community integrated prevention campaign in Western Province, Kenya, reached 47,000 individuals over 7 days, providing HIV testing and counseling, water filters, insecticide-treated bed nets, condoms, and for HIV-infected individuals cotrimoxazole prophylaxis and referral for ongoing care. We modeled the potential cost-effectiveness of a scaled-up integrated prevention campaign.We estimated averted deaths and disability-adjusted life years (DALYs) based on published data on baseline mortality and morbidity and on the protective effect of interventions, including antiretroviral therapy. We incorporate a previously estimated scaled-up campaign cost. We used published costs of medical care to estimate savings from averted illness (for all three diseases) and the added costs of initiating treatment earlier in the course of HIV disease.Per 1000 participants, projected reductions in cases of diarrhea, malaria, and HIV infection avert an estimated 16.3 deaths, 359 DALYs and 85,113inmedicalcarecosts.EarliercareforHIVinfectedpersonsaddsanestimated82DALYsaverted(toatotalof442),atacostof85,113 in medical care costs. Earlier care for HIV-infected persons adds an estimated 82 DALYs averted (to a total of 442), at a cost of 37,097 (reducing total averted costs to 48,015).Accountingfortheestimatedcampaigncostof48,015). Accounting for the estimated campaign cost of 32,000, the campaign saves an estimated 16,015per1000participants.Inmultivariatesensitivityanalyses,8316,015 per 1000 participants. In multivariate sensitivity analyses, 83% of simulations result in net savings, and 93% in a cost per DALY averted of less than 20.A mass, rapidly implemented campaign for HIV testing, safe water, and malaria control appears economically attractive

    Experimental and theoretical investigation of ligand effects on the synthesis of ZnO nanoparticles

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    ZnO nanoparticles with highly controllable particle sizes(less than 10 nm) were synthesized using organic capping ligands in Zn(Ac)2 ethanolic solution. The molecular structure of the ligands was found to have significant influence on the particle size. The multi-functional molecule tris(hydroxymethyl)-aminomethane (THMA) favoured smaller particle distributions compared with ligands possessing long hydrocarbon chains that are more frequently employed. The adsorption of capping ligands on ZnnOn crystal nuclei (where n = 4 or 18 molecular clusters of(0001) ZnO surfaces) was modelled by ab initio methods at the density functional theory (DFT) level. For the molecules examined, chemisorption proceeded via the formation of Zn...O, Zn...N, or Zn...S chemical bonds between the ligands and active Zn2+ sites on ZnO surfaces. The DFT results indicated that THMA binds more strongly to the ZnO surface than other ligands, suggesting that this molecule is very effective at stabilizing ZnO nanoparticle surfaces. This study, therefore, provides new insight into the correlation between the molecular structure of capping ligands and the morphology of metal oxide nanostructures formed in their presence

    Immigrant fertility in West Germany: is there a socialization effect in transitions to second and third births?

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    In this paper on immigrant fertility in West Germany, we estimate the transition rates to second and third births, using intensity-regression models. The data come from the German Socio-Economic Panel Study. We distinguish women of the first and the second immigrant generations originating from Turkey, the former Yugoslavia, Greece, Italy, and Spain, and compare their fertility levels to those of West German women. In the theoretical framework, we discuss competing hypotheses on migrant fertility. The findings support mainly the socialization hypothesis: the transition rates of first-generation immigrants vary by country of origin, and the fertility patterns of migrant descendants resemble more closely those of West Germans than those of the first immigrant generation. In addition, the analyses show that fertility differentials between immigrants and women of the indigenous population can largely, though not in full, be explained by compositional differences.Dans cet article relatif à la fécondité des immigrées en Allemagne, le passage du premier au deuxieme enfant et dans celui du deuxieme au troisieme enfant est estimé à partir de modèles de régression à risques instantanés. Les données utilisées proviennent de l’étude de Panel socio-économique allemand. On distingue les femmes immigrées de première ou de seconde génération originaires de Turquie, d’ex-Yougoslavie, de Grèce, d’Italie et d’Espagne, et leurs niveaux de fécondité sont comparés à ceux des femmes ouest-allemandes d’origine. Des hypothèses concurrentes sur la fécondité des immigrés sont discutées dans le cadre théorique. Les résultats vérifient principalement l’hypothèse de la socialisation : le passage au deuxieme et au troisieme enfant de la première génération d’immigrés varie selon le pays d’origine, et le profil de fécondité par âge des descendantes d’immigrées se rapproche plus de celui des femmes ouest-allemandes que de celui des immigrées de première génération. De plus, les analyses montrent que les différences de fécondité entre les immigrées et les femmes ouest-allemandes peuvent être en grande partie, mais pas totalement, expliquées par des différences de structure

    2016 AAPP Monograph Series: African American Professors Program

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    The African American Professors Program (AAPP) at the University of South Carolina is honored to publish this fifteenth edition of its annual monograph series. AAPP recognizes the significance of offering scholars a venue through which to engage actively in research and to publish their refereed papers. Parallel with the publication of their manuscripts is the opportunity to gain visibility among colleagues throughout postsecondary institutions at national and international levels. Scholars who have contributed papers for this monograph are acknowledged for embracing the value of including this responsibility within their academic milieu. Writing across disciplines adds to the intellectual diversity of these manuscripts. From neophytes to quite experienced individuals, the chapters have been researched and written in depth. Founded in 1997 through the Department of Educational Leadership and Policies in the College of Education, AAPP was designed originally to address the under-representation of African American professors on college and university campuses. Its mission is to expand the pool of these professors in critical academic and research areas. Sponsored historically by the University of South Carolina, the W.K. Kellogg Foundation, and the South Carolina General Assembly, the program recruits doctoral students for disciplines in which African Americans currently are underrepresented among faculty in higher education. The continuation of this monograph series is seen as responding to a window of opportunity to be sensitive to academic expectation of graduates as they pursue career placement and, at the same time, to allow for the dissemination of products of scholarship to a broader community. The importance of this series has been voiced by one of our 2002 AAPP graduates, Dr. Shundelle LaTjuan Dogan, formerly an Administrative Fellow at Harvard University, a Program Officer for the Southern Education Foundation, and a Program Officer for the Arthur M. Blank Foundation in Atlanta, Georgia. She is currently a Corporate Citizenship and Corporate Affairs Manager for IBM-International Business Machines in Atlanta, Georgia and has written the Foreword for the 2014 monograph. Dr. Dogan wrote: One thing in particular that I want to thank you for is having the African American Professors Program scholars publish articles for the monograph. I have to admit that writing the articles seemed like extra work at the time. However, in my recent interview process, organizations have asked me for samples of my writing. Including an article from a published monograph helped to make my portfolio much more impressive. You were \u27right on target\u27 in having us do the monograph series. (AAPP 2003 Monograph, p. xi) The African American Professors Program continues the tradition as a promoter of international scholarship in higher education evidenced through the inspiration from this group of interdisciplinary manuscripts. I hope that you will envision these published papers to serve as an invaluable contribution to your own professional development and career enhancement. John McFadden, PhD The Benjamin Elijah Mays Distinguished Professor Emeritus Director, African American Professors Program University of South Carolinahttps://scholarcommons.sc.edu/mcfadden_monographs/1003/thumbnail.jp

    HMGA1 is a novel downstream nuclear target of the insulin receptor signaling pathway

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    High-mobility group AT-hook 1 (HMGA1) protein is an important nuclear factor that activates gene transcription by binding to AT-rich sequences in the promoter region of DNA. We previously demonstrated that HMGA1 is a key regulator of the insulin receptor (INSR) gene and individuals with defects in HMGA1 have decreased INSR expression and increased susceptibility to type 2 diabetes mellitus. In addition, there is evidence that intracellular regulatory molecules that are employed by the INSR signaling system are involved in post-translational modifications of HMGA1, including protein phosphorylation. It is known that phosphorylation of HMGA1 reduces DNA-binding affinity and transcriptional activation. In the present study, we investigated whether activation of the INSR by insulin affected HMGA1 protein phosphorylation and its regulation of gene transcription. Collectively, our findings indicate that HMGA1 is a novel downstream target of the INSR signaling pathway, thus representing a new critical nuclear mediator of insulin action and function
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