83 research outputs found
A GPU Implementation for Two-Dimensional Shallow Water Modeling
In this paper, we present a GPU implementation of a two-dimensional shallow
water model. Water simulations are useful for modeling floods, river/reservoir
behavior, and dam break scenarios. Our GPU implementation shows vast
performance improvements over the original Fortran implementation. By taking
advantage of the GPU, researchers and engineers will be able to study water
systems more efficiently and in greater detail.Comment: 9 pages, 1 figur
The histone chaperones Vps75 and Nap1 form ring-like, tetrameric structures in solution
NAP-1 fold histone chaperones play an important role in escorting histones to and from sites of nucleosome assembly and disassembly. The two NAP-1 fold histone chaperones in budding yeast, Vps75 and Nap1, have previously been crystalized in a characteristic homodimeric conformation. In this study, a combination of small angle X-ray scattering, multi angle light scattering and pulsed electronβelectron double resonance approaches were used to show that both Vps75 and Nap1 adopt ring-shaped tetrameric conformations in solution. This suggests that the formation of homotetramers is a common feature of NAP-1 fold histone chaperones. The tetramerisation of NAP-1 fold histone chaperones may act to shield acidic surfaces in the absence of histone cargo thus providing a βself-chaperoningβ type mechanism
Gravitational Waves From Known Pulsars: Results From The Initial Detector Era
We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom
Detecting gravitational wave emission from the known accreting neutron stars
Detection of gravitational waves from accreting neutron stars (NSs) in our
galaxy, due to ellipticity or internal oscillation, would be a breakthrough in
our understanding of compact objects and explain the absence of NSs rotating
near the break-up limit. Direct detection, however, poses a formidable
challenge. Using the current data available on the properties of the accreting
NSs in Low Mass X-Ray Binaries (LMXBs), we quantify the detectability for the
known accreting NSs, considering various emission scenarios and taking into
account the negative impact of parameter uncertainty on the data analysis
process. Only a few of the persistently bright NSs accreting at rates near the
Eddington limit are detectable by Advanced LIGO if they are emitting
gravitational waves at a rate matching the torque from accretion. A larger
fraction of the known population is detectable if the spin and orbital
parameters are known in advance, especially with the narrow-band Advanced LIGO.
We identify the most promising targets, and list specific actions that would
lead to significant improvements in detection probability. These include
astronomical observations (especially for unknown orbital periods),
improvements in data analysis algorithms and capabilities, and further detector
development.Comment: Minor revisions, MNRAS accepte
ATP-Dependent Chromatin Remodeling Factors and Their Roles in Affecting Nucleosome Fiber Composition
ATP-dependent chromatin remodeling factors of the SNF2 family are key components of the cellular machineries that shape and regulate chromatin structure and function. Members of this group of proteins have broad and heterogeneous functions ranging from controlling gene activity, facilitating DNA damage repair, promoting homologous recombination to maintaining genomic stability. Several chromatin remodeling factors are critical components of nucleosome assembly processes, and recent reports have identified specific functions of distinct chromatin remodeling factors in the assembly of variant histones into chromatin. In this review we will discuss the specific roles of ATP-dependent chromatin remodeling factors in determining nucleosome composition and, thus, chromatin fiber properties
- β¦