4,318 research outputs found
Highly eccentric inspirals into a black hole
We model the inspiral of a compact stellar-mass object into a massive
nonrotating black hole including all dissipative and conservative
first-order-in-the-mass-ratio effects on the orbital motion. The techniques we
develop allow inspirals with initial eccentricities as high as and
initial separations as large as to be evolved through many thousands
of orbits up to the onset of the plunge into the black hole. The inspiral is
computed using an osculating elements scheme driven by a hybridized self-force
model, which combines Lorenz-gauge self-force results with highly accurate flux
data from a Regge-Wheeler-Zerilli code. The high accuracy of our hybrid
self-force model allows the orbital phase of the inspirals to be tracked to
within radians or better. The difference between self-force models
and inspirals computed in the radiative approximation is quantified.Comment: Updated to reflect published versio
Evolution of small-mass-ratio binaries with a spinning secondary
We calculate the evolution and gravitational-wave emission of a spinning
compact object inspiraling into a substantially more massive (non-rotating)
black hole. We extend our previous model for a non-spinning binary [Phys. Rev.
D 93, 064024] to include the Mathisson-Papapetrou-Dixon spin-curvature force.
For spin-aligned binaries we calculate the dephasing of the inspiral and
associated waveforms relative to models that do not include spin-curvature
effects. We find this dephasing can be either positive or negative depending on
the initial separation of the binary. For binaries in which the spin and
orbital angular momentum are not parallel, the orbital plane precesses and we
use a more general osculating element prescription to compute inspirals.Comment: 17 pages, 6 figure
The Epstein-Barr Virus Episome Maneuvers between Nuclear Chromatin Compartments during Reactivation.
The human genome is structurally organized in three-dimensional space to facilitate functional partitioning of transcription. We learned that the latent episome of the human Epstein-Barr virus (EBV) preferentially associates with gene-poor chromosomes and avoids gene-rich chromosomes. Kaposi's sarcoma-associated herpesvirus behaves similarly, but human papillomavirus does not. Contacts on the EBV side localize to OriP, the latent origin of replication. This genetic element and the EBNA1 protein that binds there are sufficient to reconstitute chromosome association preferences of the entire episome. Contacts on the human side localize to gene-poor and AT-rich regions of chromatin distant from transcription start sites. Upon reactivation from latency, however, the episome moves away from repressive heterochromatin and toward active euchromatin. Our work adds three-dimensional relocalization to the molecular events that occur during reactivation. Involvement of myriad interchromosomal associations also suggests a role for this type of long-range association in gene regulation.IMPORTANCE The human genome is structurally organized in three-dimensional space, and this structure functionally affects transcriptional activity. We set out to investigate whether a double-stranded DNA virus, Epstein-Barr virus (EBV), uses mechanisms similar to those of the human genome to regulate transcription. We found that the EBV genome associates with repressive compartments of the nucleus during latency and with active compartments during reactivation. This study advances our knowledge of the EBV life cycle, adding three-dimensional relocalization as a novel component to the molecular events that occur during reactivation. Furthermore, the data add to our understanding of nuclear compartments, showing that disperse interchromosomal interactions may be important for regulating transcription
Simulations and Data analysis for the 35 ton Liquid Argon detector as a prototype for the DUNE experiment
The Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment
which will be built at the Sanford Underground Research Facility (SURF), and will
receive a wide-band neutrino beam from Fermilab, 1300 km away. At this baseline DUNE
will be able to study many of the properties of neutrino mixing, including the neutrino mass
hierarchy and the value of the CP-violating complex phase (δCP). DUNE will utilise Liquid
Argon (LAr) Time Projection Chamber (TPC) (LArTPC) technology, and the Far Detector
(FD) will consist of four modules, each containing 17.1 kt of LAr with a fiducial mass of
around 10 kt. Each of these FD modules represents around an order of magnitude increase in
size, when compared to existing LArTPC experiments.
The 35 ton detector is the first DUNE prototype for the single (LAr) phase design of the
FD. There were two running periods, one from November 2013 to February 2014, and a
second from November 2015 to March 2016. During the second running period, a system of
TPCs was installed, and cosmic-ray data were collected. A method of particle identification
was developed using simulations, though this was not applied to the data due to the higher
than expected noise level. A new method of determining the interaction time of a track, using
the effects of longitudinal diffusion, was developed using the cosmic-ray data. A camera
system was also installed in the detector for monitoring purposes, and to look for high voltage
breakdowns.
Simulations concerning the muon-induced background rate to nucleon decay are performed,
following the incorporation of the MUon Simulations UNderground (MUSUN)
generator into the DUNE software framework. A series of cuts which are based on Monte
Carlo truth information is developed, designed to reject simulated background events, whilst
preserving simulated signal events in the n→K++e− decay channel. No background events
are seen to survive the application of these cuts in a sample of 2 × 109 muons, representing
401.6 years of detector live time. This corresponds to an annual background rate of
< 0.44 events·Mt−1·year−1 at 90% confidence, using a fiducial mass of 13.8 kt
Coaches’ dispositions and non-formal learning situations: an analysis of the ‘coach talent programme’
Research which identifies and describes the learning situations coaches engage with often overlooks how coaches’ dispositions and the ‘learning cultures’ they occupy influences their opportunities for learning, limiting our understanding of what ‘works’ and for ‘whom’. Seven coaches from five sports were interviewed regarding their experiences of ‘The Coach Talent Programme’ (CTP); a non-formal learning situation consisting of cross-sport CPD workshops delivered by a UK County Sports Partnership. Data were analysed thematically, integrating Pierre Bourdieu’s sociology alongside Phil Hodkinson’s theory of ‘learning cultures’. Three themes were developed: (1) social interaction and cross-sport learning; (2) workshop content and online learning; and (3) tutor capital and the coaching field. The findings demonstrate how coaches’ ‘learning’ within non-formal situations varies significantly due to embodied dispositions, capital, and the social fields coaches are positioned within. Sports organisations would benefit from recognising the influence of these factors to develop transformative non-formal environments for coach learning
Ethnically diverse urban transmission networks of Neisseria gonorrhoeae without evidence of HIV serosorting
Objective
We aimed to characterise gonorrhoea transmission patterns in a diverse urban population by linking genomic, epidemiological and antimicrobial susceptibility data.
Methods
Neisseria gonorrhoeae isolates from patients attending sexual health clinics at Barts Health NHS Trust, London, UK, during an eleven-month period underwent whole-genome sequencing and antimicrobial susceptibility testing. We combined laboratory and patient data to investigate the transmission network structure.
Results
One hundred and fifty-eight isolates from 158 patients were available with associated descriptive data. One hundred and twenty-nine (82%) patients identified as male and 25 (16%) as female; 4 (3%) records lacked gender information. Self-described ethnicities were: 51 (32%) English/Welsh/Scottish; 33 (21%) White, other; 23 (15%) Black British/Black African/Black, other; 12 (8%) Caribbean; 9 (6%) South Asian; 6 (4%) mixed ethnicity; 10 (6%) other; data were missing for 14 (9%). Self-reported sexual orientations were 82 (52%) men who have sex with men; 49 (31%) heterosexual; 2 (1%) bisexual; data missing for 25 individuals. Twenty-two (14%) patients were HIV-positive. Whole genome sequence data were generated for 151 isolates, which linked 75 (50%) patients to at least one other case. Using sequencing data, we found no evidence of transmission networks related to specific ethnic groups (p=0.64) or of HIV serosorting (p=0.35). Of 82 MSM/bisexual patients with sequencing data, 45 (55%) belonged to clusters of ≥2 cases, compared to 16/44 (36%) heterosexuals with sequencing data (p=0.06).
Conclusion
We demonstrate links between 50% of patients in transmission networks using a relatively small sample in a large cosmopolitan city. We found no evidence of HIV serosorting. Our results do not support assortative selectivity as an explanation for differences in gonorrhoea incidence between ethnic groups
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