5,982 research outputs found

    Fecal Virome Transplantation

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    The gut virome consists of a large population of eukaryotic and prokaryotic viruses that have an emerging role in human health and disease. Growing evidence for the importance of the virome includes recent findings on fecal virome transplantation (FVT) that suggest FVT may have therapeutic potential for the resolution of dysbiosis and treatment of dysbiosis-related disorders. Most viruses in the gut virome are bacteriophages (phages), which have a well-established role in regulating bacterial communities across environments. Phages also influence health and disease by interacting directly with the host immune system. The full extent to which gut phages should be considered as both a target and a tool for microbiome modulation remains to be seen. This chapter will explore the current understanding of the gut virome and the therapeutic potential for FVT

    Atomic ionization by sterile-to-active neutrino conversion and constraints on dark matter sterile neutrinos with germanium detectors

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    The transition magnetic moment of a sterile-to-active neutrino conversion gives rise to not only radiative decay of a sterile neutrino, but also its non-standard interaction (NSI) with matter. For sterile neutrinos of keV-mass as dark matter candidates, their decay signals are actively searched for in cosmic X-ray spectra. In this work, we consider the NSI that leads to atomic ionization, which can be detected by direct dark matter experiments. It is found that this inelastic scattering process for a nonrelativistic sterile neutrino has a pronounced enhancement in the differential cross section at energy transfer about half of its mass, manifesting experimentally as peaks in the measurable energy spectra. The enhancement effects gradually smear out as the sterile neutrino becomes relativistic. Using data taken with germanium detectors that have fine energy resolution in keV and sub-keV regimes, constraints on sterile neutrino mass and its transition magnetic moment are derived and compared with those from astrophysical observations

    Rotation periods of exoplanet host stars

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    The stellar rotation periods of ten exoplanet host stars have been determined using newly analysed Ca II H & K flux records from Mount Wilson Observatory and Stromgren b, y photometric measurements from Tennessee State University's automatic photometric telescopes (APTs) at Fairborn Observatory. Five of the rotation periods have not previously been reported, with that of HD 130322 very strongly detected at Prot = 26.1 \pm 3.5 d. The rotation periods of five other stars have been updated using new data. We use the rotation periods to derive the line-of-sight inclinations of the stellar rotation axes, which may be used to probe theories of planet formation and evolution when combined with the planetary orbital inclination found from other methods. Finally, we estimate the masses of fourteen exoplanets under the assumption that the stellar rotation axis is aligned with the orbital axis. We calculate the mass of HD 92788 b (28 MJ) to be within the low-mass brown dwarf regime and suggest that this object warrants further investigation to confirm its true nature.Comment: Accepted for publication in MNRAS. 15 pages, 11 figure

    Magnetostatic field noise near metallic surfaces

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    We develop an effective low-frequency theory of the electromagnetic field in equilibrium with thermal objects. The aim is to compute thermal magnetic noise spectra close to metallic microstructures. We focus on the limit where the material response is characterized by the electric conductivity. At the boundary between empty space and metallic microstructures, a large jump occurs in the dielectric function which leads to a partial screening of low-frequency magnetic fields generated by thermal current fluctuations. We resolve a discrepancy between two approaches used in the past to compute magnetic field noise spectra close to microstructured materials.Comment: 9 pages, 1 figure, EPJ D style, accepted in Topical Issue on "Atom Chips

    Can photo-evaporation trigger planetesimal formation?

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    We propose that UV radiation can stimulate the formation of planetesimals in externally-illuminated protoplanetary disks. We present a numerical model of disk evolution including vertical sedimentation and photo-evaporation by an external O or B star. As solid material grows and settles toward the disk midplane, the outer layers of the disk become dust depleted. When such a disk is exposed to UV radiation, heating drives photo-evaporative mass-loss from its surface, generating a dust-depleted outflow. The dust:gas surface density ratio in the disk interior grows until dust in the disk midplane becomes gravitationally unstable. Thus, UV radiation fields may induce the rapid formation of planetesimals in disks where sedimentation has occurred.Comment: 4 pages, 1 figure. Revised and accepted by ApJ

    Complete Nucleotide Sequence of Dendrocalamus Latiflorus and Bambusa Oldhamii Chloroplast Genomes

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    Although bamboo is one of the most important woody crops in Asia, information on its genome is still very limited. To investigate the relationship among Poaceae members and to understand the mechanism of albino mutant generation in vitro, the complete chloroplast genome of two economically important bamboo species, Dendrocalamus latiflorus Munro and Bambusa oldhamii Munro, was determined employing a strategy that involved polymerase chain reaction (PCR) amplification using 443 novel primers designed to amplify the chloroplast genome of these two species. The lengths of the B. oldhamii and D. latiflorus chloroplast genomes are 139,350 and 139,365 bp, respectively. The organization structure and the gene order of these two bamboos are identical to other members of Poaceae. Highly conserved chloroplast genomes of Poaceae facilitated sequencing by the PCR method. Phylogenetic analysis using both chloroplast genomes confirmed the results obtained from studies on chromosome number and reproductive organ morphology. There are 23 gaps, insertions/deletions \u3e 100 bp, in the chloroplast genomes of 10 genera of Poaceae compared in this study. The phylogenetic distribution of these gaps corresponds to their taxonomic placement. The sequences of these two chloroplast genomes provide useful information for studying bamboo evolution, ecology and biotechnology

    Planning Horizon for Production Inventory Models with Production Rate Dependent on Demand and Inventory Level

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    This paper discusses why the selection of a finite planning horizon is preferable to an infinite one for a replenishment policy of production inventory models. In a production inventory model, the production rate is dependent on both the demand rate and the inventory level. When there is an exponentially decreasing demand, the application of an infinite planning horizon model is not suitable. The emphasis of this paper is threefold. First, while pointing out questionable results from a previous study, we propose a corrected infinite planning horizon inventory model for the first replenishment cycle. Second, while investigating the optimal solution for the minimization problem, we found that the infinite planning horizon should not be applied when dealing with an exponentially decreasing demand. Third, we developed a new production inventory model under a finite planning horizon for practitioners. Numerical examples are provided to support our findings
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