22 research outputs found

    Nuclear Reaction Mechanism Study Over a Wide Target Mass Range for 6-Li and 12-C Ions

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    This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

    Population turnover in remote oceania shortly after initial settlement

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    Ancient DNA from Vanuatu and Tonga dating to about 2,900–2,600 years ago (before present, BP) has revealed that the “First Remote Oceanians” associated with the Lapita archaeological culture were directly descended from the population that, beginning around 5000 BP, spread Austronesian languages from Taiwan to the Philippines, western Melanesia, and eventually Remote Oceania. Thus, ancestors of the First Remote Oceanians must have passed by the Papuan-ancestry populations they encountered in New Guinea, the Bismarck Archipelago, and the Solomon Islands with minimal admixture [1]. However, all present-day populations in Near and Remote Oceania harbor >25% Papuan ancestry, implying that additional eastward migration must have occurred. We generated genome-wide data for 14 ancient individuals from Efate and Epi Islands in Vanuatu from 2900–150 BP, as well as 185 present-day individuals from 18 islands. We find that people of almost entirely Papuan ancestry arrived in Vanuatu by around 2300 BP, most likely reflecting migrations a few hundred years earlier at the end of the Lapita period, when there is also evidence of changes in skeletal morphology and cessation of long-distance trade between Near and Remote Oceania [2, 3]. Papuan ancestry was subsequently diluted through admixture but remains at least 80%–90% in most islands. Through a fine-grained analysis of ancestry profiles, we show that the Papuan ancestry in Vanuatu derives from the Bismarck Archipelago rather than the geographically closer Solomon Islands. However, the Papuan ancestry in Polynesia—the most remote Pacific islands—derives from different sources, documenting a third stream of migration from Near to Remote Oceania

    Recent Advances in Understanding Particle Acceleration Processes in Solar Flares

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    We review basic theoretical concepts in particle acceleration, with particular emphasis on processes likely to occur in regions of magnetic reconnection. Several new developments are discussed, including detailed studies of reconnection in three-dimensional magnetic field configurations (e.g., current sheets, collapsing traps, separatrix regions) and stochastic acceleration in a turbulent environment. Fluid, test-particle, and particle-in-cell approaches are used and results compared. While these studies show considerable promise in accounting for the various observational manifestations of solar flares, they are limited by a number of factors, mostly relating to available computational power. Not the least of these issues is the need to explicitly incorporate the electrodynamic feedback of the accelerated particles themselves on the environment in which they are accelerated. A brief prognosis for future advancement is offered.Comment: This is a chapter in a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

    Neutralizing antibody vaccine for pandemic and pre-emergent coronaviruses

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    Betacoronaviruses (betaCoVs) caused the severe acute respiratory syndrome (SARS) and Middle East Respiratory Syndrome (MERS) outbreaks, and the SARS-CoV-2 pandemic1–4. Vaccines that elicit protective immunity against SARS-CoV-2 and betaCoVs circulating in animals have the potential to prevent future betaCoV pandemics. Here, we show that macaque immunization with a multimeric SARS-CoV-2 receptor binding domain (RBD) nanoparticle adjuvanted with 3M-052/Alum elicited cross-neutralizing antibody (cross-nAb) responses against batCoVs, SARS-CoV-1, SARS-CoV-2, and SARS-CoV-2 variants B.1.1.7, P.1, and B.1.351. Nanoparticle vaccination resulted in a SARS-CoV-2 reciprocal geometric mean neutralization ID50 titer of 47,216, and protection against SARS-CoV-2 in macaque upper and lower respiratory tracts. Importantly, nucleoside-modified mRNA encoding a stabilized transmembrane spike or monomeric RBD also induced SARS-CoV-1 and batCoV cross-nAbs, albeit at lower titers. These results demonstrate current mRNA vaccines may provide some protection from future zoonotic betaCoV outbreaks, and provide a platform for further development of pan-betaCoV vaccines

    Breadth of SARS-CoV-2 neutralization and protection induced by a nanoparticle vaccine

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    Coronavirus vaccines that are highly effective against current and anticipated SARS-CoV-2 variants are needed to control COVID-19. We previously reported a receptor-binding domain (RBD)-sortase A-conjugated ferritin nanoparticle (scNP) vaccine that induced neutralizing antibodies against SARS-CoV-2 and pre-emergent sarbecoviruses and protected non-human primates (NHPs) from SARS-CoV-2 WA-1 infection. Here, we find the RBD-scNP induced neutralizing antibodies in NHPs against pseudoviruses of SARS-CoV and SARS-CoV-2 variants including 614G, Beta, Delta, Omicron BA.1, BA.2, BA.2.12.1, and BA.4/BA.5, and a designed variant with escape mutations, PMS20. Adjuvant studies demonstrate variant neutralization titers are highest with 3M-052-aqueous formulation (AF). Immunization twice with RBD-scNPs protect NHPs from SARS-CoV-2 WA-1, Beta, and Delta variant challenge, and protect mice from challenges of SARS-CoV-2 Beta variant and two other heterologous sarbecoviruses. These results demonstrate the ability of RBD-scNPs to induce broad neutralization of SARS-CoV-2 variants and to protect animals from multiple different SARS-related viruses. Such a vaccine could provide broad immunity to SARS-CoV-2 variants

    An Observational Overview of Solar Flares

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    We present an overview of solar flares and associated phenomena, drawing upon a wide range of observational data primarily from the RHESSI era. Following an introductory discussion and overview of the status of observational capabilities, the article is split into topical sections which deal with different areas of flare phenomena (footpoints and ribbons, coronal sources, relationship to coronal mass ejections) and their interconnections. We also discuss flare soft X-ray spectroscopy and the energetics of the process. The emphasis is to describe the observations from multiple points of view, while bearing in mind the models that link them to each other and to theory. The present theoretical and observational understanding of solar flares is far from complete, so we conclude with a brief discussion of models, and a list of missing but important observations.Comment: This is an article for a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

    Global Properties of Solar Flares

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    UK doubles its "world-leading" research in Life Sciences and Medicine in six years: Testing the claim?

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    The UK, like some other countries, carries out a periodic review of research quality in universities and the most recent Research Excellence Framework (REF) reported a doubling (103% increase) in its "world leading" or so-called "4*" research outputs in the areas of life sciences and medicine between 2008 and 2014. This is a remarkable improvement in six years and if validated internationally could have profound implications for health sciences.We compared the reported changes in 4* quality to bibliometric measures of quality for the 56,639 articles submitted to the RAE 2008 and the 50,044 articles submitted to the REF 2014 to Panel A, which assesses the life sciences, including medicine.UK research submitted to the RAE and REF was of better quality than worldwide research on average. While we found evidence for some increase in the quality of top UK research articles, a 10-25% increase in the top 10%ile papers, depending upon the metrics used, we could not find evidence to support a 103% increase in quality. Instead we found that as compared to the RAE, the REF results implied a lower citation %ile threshold for declaring a 4*.There is a wide discrepancy between bibliometric indices and peer-review panel judgements between the RAE 2008 and REF 2014. It is possible that the changes in the funding regime between 2008 and 2014 that significantly increased the financial premium for 4* articles may have influenced research quality evaluation. For the advancement of science and health, evaluation of research quality requires consistency and validity - the discrepancy noted here calls for a closer examination of mass peer-review methods like the REF

    XAFS Determination of As(V) Associated with Fe(III) Oxyhydroxides in Weathered Mine Tailings and Contaminated Soil from California, U.S.A.

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    The speciation of Arsenic (As) in soils and natural waters is critical in determining its environmental fate. As(III) is the most mobile and toxic of the inorganic arsenic species, but is readily oxidized to As(V), which although still quite toxic is far less mobile. Adsorption to sediment particles may remove As(V) from contaminated water, or the precipitation of arsenic minerals such as scorodite (FeAsO4·2H2O) may control the equilibrium aqueous concentration. We have employed XAFS spectroscopy to examine the solid-phase speciation of arsenic in mine tailings samples and a contaminated soil from California. Quantitative speciation of As was determined using XANES fitting methods and EXAFS analysis ; in all samples, As(V) predominates. In an oxidized tailings (no residual sulfides), we find As(V) adsorbed/coprecipitated on Fe(III) oxyhydroxides. In less oxidized tailings containing residual sulfides, there is evidence for scorodite a a similar Fe(III) arsenate and a reduced arsenic phase (arsenopyrite or arseniferous pyrite). In a soil contaminated by smelter waste, we detect Mg3(AsO4)2·8 H2O (hoernesite), and suggest the presence of an additional weakly bound As(V) species. XAFS spectroscopy is one of the few techniques for direct determination of arsenic speciation in complex matrices such as soils and mine tailings
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