876 research outputs found
Fibrosis in the kidney: is a problem shared a problem halved?
Fibrotic disorders are commonplace, take many forms and can be life-threatening. No better example of this exists than the progressive fibrosis that accompanies all chronic renal disease. Renal fibrosis is a direct consequence of the kidney's limited capacity to regenerate after injury. Renal scarring results in a progressive loss of renal function, ultimately leading to end-stage renal failure and a requirement for dialysis or kidney transplantation
Calibration of the LIGO displacement actuators via laser frequency modulation
We present a frequency modulation technique for calibration of the
displacement actuators of the LIGO 4-km-long interferometric gravitational-wave
detectors. With the interferometer locked in a single-arm configuration, we
modulate the frequency of the laser light, creating an effective length
variation that we calibrate by measuring the amplitude of the frequency
modulation. By simultaneously driving the voice coil actuators that control the
length of the arm cavity, we calibrate the voice coil actuation coefficient
with an estimated 1-sigma uncertainty of less than one percent. This technique
enables a force-free, single-step actuator calibration using a displacement
fiducial that is fundamentally different from those employed in other
calibration methods.Comment: 10 pages, 5 figures, submitted to Classical and Quantum Gravit
A template bank for gravitational waveforms from coalescing binary black holes: non-spinning binaries
Gravitational waveforms from the inspiral and ring-down stages of the binary
black hole coalescences can be modelled accurately by
approximation/perturbation techniques in general relativity. Recent progress in
numerical relativity has enabled us to model also the non-perturbative merger
phase of the binary black-hole coalescence problem. This enables us to
\emph{coherently} search for all three stages of the coalescence of
non-spinning binary black holes using a single template bank. Taking our
motivation from these results, we propose a family of template waveforms which
can model the inspiral, merger, and ring-down stages of the coalescence of
non-spinning binary black holes that follow quasi-circular inspiral. This
two-dimensional template family is explicitly parametrized by the physical
parameters of the binary. We show that the template family is not only
\emph{effectual} in detecting the signals from black hole coalescences, but
also \emph{faithful} in estimating the parameters of the binary. We compare the
sensitivity of a search (in the context of different ground-based
interferometers) using all three stages of the black hole coalescence with
other template-based searches which look for individual stages separately. We
find that the proposed search is significantly more sensitive than other
template-based searches for a substantial mass-range, potentially bringing
about remarkable improvement in the event-rate of ground-based interferometers.
As part of this work, we also prescribe a general procedure to construct
interpolated template banks using non-spinning black hole waveforms produced by
numerical relativity.Comment: A typo fixed in Eq.(B11
Bayesian inference on compact binary inspiral gravitational radiation signals in interferometric data
Presented is a description of a Markov chain Monte Carlo (MCMC) parameter
estimation routine for use with interferometric gravitational radiational data
in searches for binary neutron star inspiral signals. Five parameters
associated with the inspiral can be estimated, and summary statistics are
produced. Advanced MCMC methods were implemented, including importance
resampling and prior distributions based on detection probability, in order to
increase the efficiency of the code. An example is presented from an
application using realistic, albeit fictitious, data.Comment: submitted to Classical and Quantum Gravity. 14 pages, 5 figure
Different atmospheric moisture divergence responses to extreme and moderate El Niños
On seasonal and inter-annual time scales, vertically integrated moisture divergence provides a useful measure of the tropical atmospheric hydrological cycle. It reflects the combined dynamical and thermodynamical effects, and is not subject to the limitations that afflict observations of evaporation minus precipitation. An empirical orthogonal function (EOF) analysis of the tropical Pacific moisture divergence fields calculated from the ERA-Interim reanalysis reveals the dominant effects of the El Niño-Southern Oscillation (ENSO) on inter-annual time scales. Two EOFs are necessary to capture the ENSO signature, and regression relationships between their Principal Components and indices of equatorial Pacific sea surface temperature (SST) demonstrate that the transition from strong La Niña through to extreme El Niño events is not a linear one. The largest deviation from linearity is for the strongest El Niños, and we interpret that this arises at least partly because the EOF analysis cannot easily separate different patterns of responses that are not orthogonal to each other. To overcome the orthogonality constraints, a self-organizing map (SOM) analysis of the same moisture divergence fields was performed. The SOM analysis captures the range of responses to ENSO, including the distinction between the moderate and strong El Niños identified by the EOF analysis. The work demonstrates the potential for the application of SOM to large scale climatic analysis, by virtue of its easier interpretation, relaxation of orthogonality constraints and its versatility for serving as an alternative classification method. Both the EOF and SOM analyses suggest a classification of “moderate” and “extreme” El Niños by their differences in the magnitudes of the hydrological cycle responses, spatial patterns and evolutionary paths. Classification from the moisture divergence point of view shows consistency with results based on other physical variables such as SST
A structurally distinct TGF-β mimic from an intestinal helminth parasite potently induces regulatory T cells
Helminth parasites defy immune exclusion through sophisticated evasion mechanisms, including activation of host immunosuppressive regulatory T (Treg) cells. The mouse parasite Heligmosomoides polygyrus can expand the host Treg population by secreting products that activate TGF-β signalling, but the identity of the active molecule is unknown. Here we identify an H. polygyrus TGF-β mimic (Hp-TGM) that replicates the biological and functional properties of TGF-β, including binding to mammalian TGF-β receptors and inducing mouse and human Foxp3+ Treg cells. Hp-TGM has no homology with mammalian TGF-β or other members of the TGF-β family, but is a member of the complement control protein superfamily. Thus, our data indicate that through convergent evolution, the parasite has acquired a protein with cytokine-like function that is able to exploit an endogenous pathway of immunoregulation in the host
Phenomenological template family for black-hole coalescence waveforms
Recent progress in numerical relativity has enabled us to model the
non-perturbative merger phase of the binary black-hole coalescence problem.
Based on these results, we propose a phenomenological family of waveforms which
can model the inspiral, merger, and ring-down stages of black hole coalescence.
We also construct a template bank using this family of waveforms and discuss
its implementation in the search for signatures of gravitational waves produced
by black-hole coalescences in the data of ground-based interferometers. This
template bank might enable us to extend the present inspiral searches to
higher-mass binary black-hole systems, i.e., systems with total mass greater
than about 80 solar masses, thereby increasing the reach of the current
generation of ground-based detectors.Comment: Minor changes, Submitted to Class. Quantum Grav. (Proc. GWDAW11
A comparison of methods for gravitational wave burst searches from LIGO and Virgo
The search procedure for burst gravitational waves has been studied using 24
hours of simulated data in a network of three interferometers (Hanford 4-km,
Livingston 4-km and Virgo 3-km are the example interferometers). Several
methods to detect burst events developed in the LIGO Scientific Collaboration
(LSC) and Virgo collaboration have been studied and compared. We have performed
coincidence analysis of the triggers obtained in the different interferometers
with and without simulated signals added to the data. The benefits of having
multiple interferometers of similar sensitivity are demonstrated by comparing
the detection performance of the joint coincidence analysis with LSC and Virgo
only burst searches. Adding Virgo to the LIGO detector network can increase by
50% the detection efficiency for this search. Another advantage of a joint
LIGO-Virgo network is the ability to reconstruct the source sky position. The
reconstruction accuracy depends on the timing measurement accuracy of the
events in each interferometer, and is displayed in this paper with a fixed
source position example.Comment: LIGO-Virgo working group submitted to PR
Anakinra reduces blood pressure and renal fibrosis in one kidney/DOCA/salt-induced hypertension
OBJECTIVE: To determine whether a clinically-utilised IL-1 receptor antagonist, anakinra, reduces renal inflammation, structural damage and blood pressure (BP) in mice with established hypertension. METHODS: Hypertension was induced in male mice by uninephrectomy, deoxycorticosterone acetate (2.4mg/d,s.c.) and replacement of drinking water with saline (1K/DOCA/salt). Control mice received uninephrectomy, a placebo pellet and normal drinking water. 10days post-surgery, mice commenced treatment with anakinra (75mg/kg/d, i.p.) or vehicle (0.9% saline, i.p.) for 11 days. Systolic BP was measured by tail cuff while qPCR, immunohistochemistry and flow cytometry were used to measure inflammatory markers, collagen and immune cell infiltration in the kidneys. RESULTS: By 10 days post-surgery, 1K/DOCA/salt-treated mice displayed elevated systolic BP (148.3+/-2.4mmHg) compared to control mice (121.7+/-2.7mmHg; n=18, P\u3c0.0001). The intervention with anakinra reduced BP in 1K/DOCA/salt-treated mice by approximately 20mmHg (n=16, P\u3c0.05), but had no effect in controls. In 1K/DOCA/salt-treated mice, anakinra modestly reduced ( approximately 30%) renal expression of some (CCL5, CCL2; n=7-8; P\u3c0.05) but not all (ICAM-1, IL-6) inflammatory markers, and had no effect on immune cell infiltration (n=7-8, P \u3e 0.05). Anakinra reduced renal collagen content (n=6, P\u3c0.01) but paradoxically appeared to exacerbate the renal and glomerular hypertrophy (n=8-9, P\u3c0.001) that accompanied 1K/DOCA/salt-induced hypertension. CONCLUSION: Despite its anti-hypertensive and renal anti-fibrotic actions, anakinra had minimal effects on inflammation and leukocyte infiltration in mice with 1K/DOCA/salt-induced hypertension. Future studies will assess whether the anti-hypertensive actions of anakinra are mediated by protective actions in other BP-regulating or salt-handling organs such as the arteries, skin and brain
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