849 research outputs found

    Blue spectra and induced formation of primordial black holes

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    We investigate the statistical properties of primordial black hole (PBH) formation in the very early Universe. We show that the high level of inhomogeneity of the early Universe leads to the formation of the first generation PBHs. %The existence of these PBHs This causes later the appearance of a dust-like phase of the cosmological expansion. We discuss here a new mechanism for the second generation of PBH formation during the dust-like phase. This mechanism is based on the coagulation process. We demonstrate that the blue power spectrum of initial adiabatic perturbations after inflation leads to overproduction of primordial black holes with 10910^9gM1015\le M\le10^{15}g if the power index is n1.2n\ge1.2.Comment: 16 pages, 2 figure

    The RESOLVE and ECO Gas in Galaxy Groups Initiative: The Group Finder and the Group HI–Halo Mass Relation

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    We present a four-step group-finding algorithm for the Gas in Galaxy Groups (G3) initiative, a spin-off of the z ∼ 0 REsolved Spectroscopy Of a Local VolumE (RESOLVE) and Environmental COntext (ECO) surveys. In preparation for future comparisons to intermediate redshift (e.g., the LADUMA survey), we design the group finder to adapt to incomplete, shallow, or nonuniform data. We use mock catalogs to optimize the group finder’s performance. Compared to friends-of-friends (with false-pair splitting), the G3 algorithm offers improved completeness and halo-mass recovery with minimal loss of purity. Combining it with the volume-limited H I census data for RESOLVE and ECO, we examine the H I content of galaxy groups as a function of group halo mass. Group-integrated H I mass M rises monotonically over halo masses M ∼ 10–10 M, pivoting in slope at M ∼ 10M, the gas-richness threshold scale. We present the first measurement of the scatter in this relation, which has a median of ∼0.3 dex and is asymmetric toward lower M I,grp. We discuss interesting tensions with theoretical predictions and prior measurements of the M–M relation. In an appendix, we release RESOLVE DR4 and ECO DR3, including updates to survey redshifts, photometry, and group catalogs, as well as a major expansion of the ECO H I inventory with value-added data products. © 2023. The Author(s). Published by the American Astronomical SocietyWe are grateful to the anonymous referee, whose feedback has improved the quality of this work. We also thank Adrienne Erickcek, Andrew Mann, Mugdha Polimera, Matthew Bershady, Joshua Oppor, Jeremy Darling, Hayley Roberts, and Amir Kazemi-Moridani for valuable feedback at varying stages of the project. Z.L.H., S.J.K., and E.R.C. acknowledge support for this research from National Science Foundation (NSF) grant AST-1814486. Z.L.H. and D.S.C. are also supported through a North Carolina Space Grant Graduate Research Fellowship. S.J.K. and D.S.C. acknowledge support from NSF grant AST-2007351. A.J.B. acknowledges support from NSF grant AST-1814421. K.M.H. acknowledges financial support from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the "Center of Excellence Severo Ocho" awarded to the Instituto de Astrofisica de Andalucia (SEV-2017-0709), via participation in SKA-SPAIN, funded by the Ministry of Science and Innovation (MCIN), and financial support from grant RTI2018-096228-B-C31 (MCIU/AEI/FEDER,UE)

    Characterizing Loop Dynamics and Ligand Recognition in Human- and Avian-Type Influenza Neuraminidases via Generalized Born Molecular Dynamics and End-Point Free Energy Calculations

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    The comparative dynamics and inhibitor binding free energies of group-1 and group-2 pathogenic influenza A subtype neuraminidase (NA) enzymes are of fundamental biological interest and relevant to structure-based drug design studies for antiviral compounds. In this work, we present seven generalized Born molecular dynamics simulations of avian (N1)- and human (N9)-type NAs in order to probe the comparative flexibility of the two subtypes, both with and without the inhibitor oseltamivir bound. The enhanced sampling obtained through the implicit solvent treatment suggests several provocative insights into the dynamics of the two subtypes, including that the group-2 enzymes may exhibit similar motion in the 430-binding site regions but different 150-loop motion. End-point free energy calculations elucidate the contributions to inhibitor binding free energies and suggest that entropic considerations cannot be neglected when comparing across the subtypes. We anticipate the findings presented here will have broad implications for the development of novel antiviral compounds against both seasonal and pandemic influenza strains

    Current challenges in software solutions for mass spectrometry-based quantitative proteomics

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    This work was in part supported by the PRIME-XS project, grant agreement number 262067, funded by the European Union seventh Framework Programme; The Netherlands Proteomics Centre, embedded in The Netherlands Genomics Initiative; The Netherlands Bioinformatics Centre; and the Centre for Biomedical Genetics (to S.C., B.B. and A.J.R.H); by NIH grants NCRR RR001614 and RR019934 (to the UCSF Mass Spectrometry Facility, director: A.L. Burlingame, P.B.); and by grants from the MRC, CR-UK, BBSRC and Barts and the London Charity (to P.C.

    A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

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    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000

    Direct application of plasmid DNA containing type I interferon transgenes to vaginal mucosa inhibits HSV-2 mediated mortality

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    The application of naked DNA containing type I interferon (IFN) transgenes is a promising potential therapeutic approach for controlling chronic viral infections. Herein, we detail the application of this approach that has been extensively used to restrain ocular HSV-1 infection, for antagonizing vaginal HSV-2 infection. We show that application of IFN-α1, -α5, and –β transgenes to vaginal mouse lumen 24 hours prior to HSV-2 infection reduces HSV-2 mediated mortality by 2.5 to 3-fold. However, other type I IFN transgenes (IFN- α4, -α5, -α6, and –α9) are non effectual against HSV-2. We further show that the efficacy of IFN-α1 transgene treatment is independent of CD4+ T lymphocytes. However, in mice depleted of CD8+ T lymphocytes, the ability of IFN-α1 transgene treatment to antagonize HSV-2 was lost

    The Formation of the First Massive Black Holes

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    Supermassive black holes (SMBHs) are common in local galactic nuclei, and SMBHs as massive as several billion solar masses already exist at redshift z=6. These earliest SMBHs may grow by the combination of radiation-pressure-limited accretion and mergers of stellar-mass seed BHs, left behind by the first generation of metal-free stars, or may be formed by more rapid direct collapse of gas in rare special environments where dense gas can accumulate without first fragmenting into stars. This chapter offers a review of these two competing scenarios, as well as some more exotic alternative ideas. It also briefly discusses how the different models may be distinguished in the future by observations with JWST, (e)LISA and other instruments.Comment: 47 pages with 306 references; this review is a chapter in "The First Galaxies - Theoretical Predictions and Observational Clues", Springer Astrophysics and Space Science Library, Eds. T. Wiklind, V. Bromm & B. Mobasher, in pres

    Combination antiretroviral therapy and the risk of myocardial infarction

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    The RESOLVE and ECO Gas in Galaxy Groups Initiative: The Group Finder and the Group H i –Halo Mass Relation

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    We present a four-step group-finding algorithm for the Gas in Galaxy Groups (G3) initiative, a spin-off of the z ∼ 0 REsolved Spectroscopy Of a Local VolumE (RESOLVE) and Environmental COntext (ECO) surveys. In preparation for future comparisons to intermediate redshift (e.g., the LADUMA survey), we design the group finder to adapt to incomplete, shallow, or nonuniform data. We use mock catalogs to optimize the group finder’s performance. Compared to friends-of-friends (with false-pair splitting), the G3 algorithm offers improved completeness and halo-mass recovery with minimal loss of purity. Combining it with the volume-limited H i census data for RESOLVE and ECO, we examine the H i content of galaxy groups as a function of group halo mass. Group-integrated H i mass M H I,grp rises monotonically over halo masses M halo ∼ 1011–1014.5 M ⊙, pivoting in slope at M halo ∼ 1011.4 M ⊙, the gas-richness threshold scale. We present the first measurement of the scatter in this relation, which has a median of ∼0.3 dex and is asymmetric toward lower M H I,grp. We discuss interesting tensions with theoretical predictions and prior measurements of the M H I,grp–M halo relation. In an appendix, we release RESOLVE DR4 and ECO DR3, including updates to survey redshifts, photometry, and group catalogs, as well as a major expansion of the ECO H i inventory with value-added data products
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