1,913 research outputs found
On physical nanoscale aspects of compatibility of steels with hydrogen and natural gas
The possibilities of effective solutions of relevant technological problems are considered based on the analysis of fundamental physical aspects, elucidation of the nano-structural mechanisms and interrelations of aging and hydrogen embrittlement of materials (steels) in the hydrogen industry and gas-main industries. The adverse effects which these mechanisms and processes have on the service properties and technological lifetime of materials are analyzed. The concomitant fundamental process of formation of carbohydride-like and other segregation nanostructures at dislocations (with the segregation capacity 1 to 1.5 orders of magnitude greater than in the widely used Cottrell 'atmosphere' model) and grain boundaries is discussed in the context of how these nanostructures affect technological processes (aging, hydrogen embrittlement, stress corrosion damage, and failure) and the physicomechanical properties of the metallic materials (including the technological lifetimes of pipeline steels)
The Use of low-dosage irradiation to the pituitary and ovaries in the treatment of amenorrhea and sterility in women
A New Waveform Consistency Test for Gravitational Wave Inspiral Searches
Searches for binary inspiral signals in data collected by interferometric
gravitational wave detectors utilize matched filtering techniques. Although
matched filtering is optimal in the case of stationary Gaussian noise, data
from real detectors often contains "glitches" and episodes of excess noise
which cause filter outputs to ring strongly. We review the standard \chi^2
statistic which is used to test whether the filter output has appropriate
contributions from several different frequency bands. We then propose a new
type of waveform consistency test which is based on the time history of the
filter output. We apply one such test to the data from the first LIGO science
run and show that it cleanly distinguishes between true inspiral waveforms and
large-amplitude false signals which managed to pass the standard \chi^2 test.Comment: 10 pages, 6 figures, submitted to Classical and Quantum Gravity for
the proceedings of the Eighth Gravitational Wave Data Analysis Workshop
(GWDAW-8
Comparison of post-Newtonian templates for compact binary inspiral signals in gravitational-wave detectors
The two-body dynamics in general relativity has been solved perturbatively
using the post-Newtonian (PN) approximation. The evolution of the orbital phase
and the emitted gravitational radiation are now known to a rather high order up
to O(v^8), v being the characteristic velocity of the binary. The orbital
evolution, however, cannot be specified uniquely due to the inherent freedom in
the choice of parameter used in the PN expansion as well as the method pursued
in solving the relevant differential equations. The goal of this paper is to
determine the (dis)agreement between different PN waveform families in the
context of initial and advanced gravitational-wave detectors. The waveforms
employed in our analysis are those that are currently used by Initial
LIGO/Virgo, that is the time-domain PN models TaylorT1, TaylorT2, TaylorT3,
TaylorT4 and TaylorEt, the effective one-body (EOB) model, and the
Fourier-domain representation TaylorF2. We examine the overlaps of these models
with one another and with the prototype effective one-body model (calibrated to
numerical relativity simulations, as currently used by initial LIGO) for a
number of different binaries at 2PN, 3PN and 3.5PN orders to quantify their
differences and to help us decide whether there exist preferred families that
are the most appropriate as search templates. We conclude that as long as the
total mass remains less than a certain upper limit M_crit, all template
families at 3.5PN order (except TaylorT3 and TaylorEt) are equally good for the
purpose of detection. The value of M_crit is found to be ~ 12M_Sun for Initial,
Enhanced and Advanced LIGO. From a purely computational point of view we
recommend that 3.5PN TaylorF2 be used below Mcrit and EOB calibrated to
numerical relativity simulations be used for total binary mass M > Mcrit.Comment: 27 pages, 8 figures, 4 tables, submitted to PR
A tapering window for time-domain templates and simulated signals in the detection of gravitational waves from coalescing compact binaries
Inspiral signals from binary black holes, in particular those with masses in
the range 10M_\odot \lsim M \lsim 1000 M_\odot, may last for only a few
cycles within a detector's most sensitive frequency band. The spectrum of a
square-windowed time-domain signal could contain unwanted power that can cause
problems in gravitational wave data analysis, particularly when the waveforms
are of short duration. There may be leakage of power into frequency bins where
no such power is expected, causing an excess of false alarms. We present a
method of tapering the time-domain waveforms that significantly reduces
unwanted leakage of power, leading to a spectrum that agrees very well with
that of a long duration signal. Our tapered window also decreases the false
alarms caused by instrumental and environmental transients that are picked up
by templates with spurious signal power. The suppression of background is an
important goal in noise-dominated searches and can lead to an improvement in
the detection efficiency of the search algorithms
Discovery and Characterization of the Cryptic Psi Subunit of the Pseudomonad DNA Replicase
We previously reconstituted a minimal DNA replicase from Pseudomonas aeruginosa consisting of α and ϵ (polymerase and editing nuclease), β (processivity factor), and the essential τ, δ, and δ′ components of the clamp loader complex (Jarvis, T., Beaudry, A., Bullard, J., Janjic, N., and McHenry, C. (2005) J. Biol. Chem. 280, 7890-7900). In Escherichia coli DNA polymerase III holoenzyme, χ and Ψ are tightly associated clamp loader accessory subunits. The addition of E. coli χΨ to the minimal P. aeruginosa replicase stimulated its activity, suggesting the existence of χ and Ψ counterparts in P. aeruginosa. The P. aeruginosa χ subunit was recognizable from sequence similarity, but Ψ was not. Here we report purification of an endogenous replication complex from P. aeruginosa. Identification of the components led to the discovery of the cryptic Ψ subunit, encoded by holD. P. aeruginosa χ and Ψ were co-expressed and purified as a 1:1 complex. P. aeruginosa χΨ increased the specific activity of τ3δδ′ 25-fold and enabled the holoenzyme to function under physiological salt conditions. A synergistic effect between χΨ and single-stranded DNA binding protein was observed. Sequence similarity to P. aeruginosa Ψ allowed us to identify Ψ subunits from several other Pseudomonads and to predict probable translational start sites for this protein family. This represents the first identification of a highly divergent branch of the Ψ family and confirms the existence of Ψ in several organisms in which Ψ was not identifiable based on sequence similarity alone
Reduced basis catalogs for gravitational wave templates
We introduce a reduced basis approach as a new paradigm for modeling,
representing and searching for gravitational waves. We construct waveform
catalogs for non-spinning compact binary coalescences, and we find that for
accuracies of 99% and 99.999% the method generates a factor of about
fewer templates than standard placement methods. The continuum of gravitational
waves can be represented by a finite and comparatively compact basis. The
method is robust under variations in the noise of detectors, implying that only
a single catalog needs to be generated.Comment: Minor changes in some of the phrasing to match the version as
published in PR
The Temporal Dynamics of Voluntary Emotion Regulation
Background: Neuroimaging has demonstrated that voluntary emotion regulation is effective in reducing amygdala activation to aversive stimuli during regulation. However, to date little is known about the sustainability of these neural effects once active emotion regulation has been terminated. Methodology/Principal Findings: We addressed this issue by means of functional magnetic resonance imaging (fMRI) in healthy female subjects. We performed an active emotion regulation task using aversive visual scenes (task 1) and a subsequent passive viewing task using the same stimuli (task 2). Here we demonstrate not only a significantly reduced amygdala activation during active regulation but also a sustained regulation effect on the amygdala in the subsequent passive viewing task. This effect was related to an immediate increase of amygdala signal in task 1 once active emotion regulation has been terminated: The larger this peak postregulation signal in the amygdala in task 1, the smaller the sustained regulation effect in task 2. Conclusions/Significance: In summary, we found clear evidence that effects of voluntary emotion regulation extend beyond the period of active regulation. These findings are of importance for the understanding of emotion regulation i
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