2,878 research outputs found
Multi-messenger astronomy of gravitational-wave sources with flexible wide-area radio transient surveys
We explore opportunities for multi-messenger astronomy using gravitational
waves (GWs) and prompt, transient low-frequency radio emission to study highly
energetic astrophysical events. We review the literature on possible sources of
correlated emission of gravitational waves and radio transients, highlighting
proposed mechanisms that lead to a short-duration, high-flux radio pulse
originating from the merger of two neutron stars or from a superconducting
cosmic string cusp. We discuss the detection prospects for each of these
mechanisms by low-frequency dipole array instruments such as LWA1, LOFAR and
MWA. We find that a broad range of models may be tested by searching for radio
pulses that, when de-dispersed, are temporally and spatially coincident with a
LIGO/Virgo GW trigger within a \usim 30 second time window and \usim 200
\mendash 500 \punits{deg}^{2} sky region. We consider various possible
observing strategies and discuss their advantages and disadvantages. Uniquely,
for low-frequency radio arrays, dispersion can delay the radio pulse until
after low-latency GW data analysis has identified and reported an event
candidate, enabling a \emph{prompt} radio signal to be captured by a
deliberately targeted beam. If neutron star mergers do have detectable prompt
radio emissions, a coincident search with the GW detector network and
low-frequency radio arrays could increase the LIGO/Virgo effective search
volume by up to a factor of \usim 2. For some models, we also map the
parameter space that may be constrained by non-detections.Comment: 31 pages, 4 figure
Electromagnetic follow-up of gravitational wave transient signal candidates
Pioneering efforts aiming at the development of multi-messenger gravitational
wave and electromagnetic astronomy have been made. An electromagnetic
observation follow-up program of candidate gravitational wave events has been
performed (Dec 17 2009 to Jan 8 2010 and Sep 4 to Oct 20 2010) during the
recent runs of the LIGO and Virgo gravitational wave detectors. It involved
ground-based and space electromagnetic facilities observing the sky at optical,
X-ray and radio wavelengths. The joint gravitational wave and electromagnetic
observation study requires the development of specific image analysis
procedures able to discriminate the possible electromagnetic counterpart of
gravitational wave triggers from contaminant/background events. The paper
presents an overview of the electromagnetic follow-up program and the image
analysis procedures.Comment: Proceedings of the 12th International Conference on "Topics in
Astroparticle and Underground Physics" (TAUP 2011), Munich, September 2011
(to appear in IoP Journal of Physics: Conference Series
Enhancing gravitational wave astronomy with galaxy catalogues
Joint gravitational wave (GW) and electromagnetic (EM) observations, as a key
research direction in multi-messenger astronomy, will provide deep insight into
the astrophysics of a vast range of astronomical phenomena. Uncertainties in
the source sky location estimate from gravitational wave observations mean
follow-up observatories must scan large portions of the sky for a potential
companion signal. A general frame of joint GW-EM observations is presented by a
multi-messenger observational triangle. Using a Bayesian approach to
multi-messenger astronomy, we investigate the use of galaxy catalogue and host
galaxy information to reduce the sky region over which follow-up observatories
must scan, as well as study its use for improving the inclination angle
estimates for coalescing binary compact objects. We demonstrate our method
using a simulated neutron stars inspiral signal injected into simulated
Advanced detectors noise and estimate the injected signal sky location and
inclination angle using the Gravitational Wave Galaxy Catalogue. In this case
study, the top three candidates in rank have , and posterior
probability of being the host galaxy, receptively. The standard deviation of
cosine inclination angle (0.001) of the neutron stars binary using
gravitational wave-galaxy information is much smaller than that (0.02) using
only gravitational wave posterior samples.Comment: Proceedings of the Sant Cugat Forum on Astrophysics. 2014 Session on
'Gravitational Wave Astrophysics
Is it possible to enhance immune response after vaccination? The role of a probiotic with a proven positive effect on all components of the immune system
Preventive vaccination is currently the most affordable and economical way to reduce morbidity and mortality from many infections, improve quality and human life expectancy with an almost ideal balance of benefits and risks among all medical procedures. The article deals with the reasons for variability of the immune response caused by vaccines, between individuals and between populations, which is of fundamental importance for human health. The authors have presented data indicating a key role of the gut microbiota in the control of the immune response to vaccination. Particular attention is paid to the microbial diversity in different loci of the body. The role of microorganisms in the proper functioning of the body and the formation of a number of pathological conditions is described. Most modern vaccines are live-attenuated, killed / inactivated or subunit (recombinant) vaccines, and they are designed for the parenteral route of administration. Most of these vaccines elicit a weak immune response, especially in the mucous membranes, due to the route of administration and are associated with weak cell-mediated immunity. Therefore, mechanisms that can enhance virus-specific vaccine immunity in infants and children are required, such as the use of more potent or selective immunity-enhancing adjuvants. Some probiotic strains may be considered as promising vaccine adjuvants. This article evaluates the recent clinical studies of probiotics used to enhance vaccine-specific immunity in adults and infants. The present-day knowledge on the role of the probiotic strain Lactobacillus rhamnosus GG with the aim of activating immunity after vaccination are presented
Infant colic: from theory to practice
Infant colic is one of the most common, yet least studied, functional disorders of the gastrointestinal tract. Until now, there is no certainty both in the understanding of the nature of this condition and in the approaches to its correction. At the same time, infant crying is of concern to parents, forcing them to seek professional help and incur considerable medical expenses and to resort, sometimes unreasonably, to dietary and medical corrections. This article provides information on the etiology, pathogenesis and management of infantile colic from an evidence-based perspective, based on a review of the current literature. Various preconditions for the occurrence and development of infantile colic are analysed in detail, none of which can affect all occurrences. Evidence for the proven efficacy of including Lactobacillus reuteri in the treatment of intestinal colic in infants is presented. Effects on the gastrointestinal tract microbiome can be of undeniable benefit. Lactobacillus reuteri is one of the most studied and scientifically documented probiotics. 203 completed clinical trials involving 17,200 participants, including 67 trials involving 8,200 participants between 0 and 3 years of age. Numerous placebo-controlled studies have shown that taking Lactobacillus reuteri DSM 17938 can significantly reduce crying time in infants with colic, and in these studies, rates of 50% or more reduction in crying time were 2.3 times higher compared to controls
Observations of Giant Pulses from Pulsar PSR B0950+08 using LWA1
We report the detection of giant pulse emission from PSR B0950+08 in 24 hours
of observations made at 39.4 MHz, with a bandwidth of 16 MHz, using the first
station of the Long Wavelength Array, LWA1. We detected 119 giant pulses from
PSR B0950+08 (at its dispersion measure), which we define as having SNRs at
least 10 times larger than for the mean pulse in our data set. These 119 pulses
are 0.035% of the total number of pulse periods in the 24 hours of
observations. The rate of giant pulses is about 5.0 per hour. The cumulative
distribution of pulse strength is a steep power law, , but much less steep than would be expected if we were observing the
tail of a Gaussian distribution of normal pulses. We detected no other
transient pulses in a dispersion measure range from 1 to 90 pc cm, in
the beam tracking PSR B0950+08. The giant pulses have a narrower temporal width
than the mean pulse (17.8 ms, on average, vs. 30.5 ms). The pulse widths are
consistent with a previously observed weak dependence on observing frequency,
which may be indicative of a deviation from a Kolmogorov spectrum of electron
density irregularities along the line of sight. The rate and strength of these
giant pulses is less than has been observed at 100 MHz. Additionally, the
mean (normal) pulse flux density we observed is less than at 100 MHz.
These results suggest this pulsar is weaker and produces less frequent giant
pulses at 39 MHz than at 100 MHz.Comment: 27 pages, 12 figures, typos correcte
Air pollution exposure and risk of adverse obstetric and neonatal outcomes among women with type 1 diabetes
Aims/Hypothesis: Women with type 1 diabetes have increased risk for poor obstetric outcomes. Prenatal air pollution exposure is also associated with adverse outcomes for women and infants. We examined whether women with type 1 diabetes are more vulnerable than other women to pollution-associated risks during pregnancy. Methods: In singleton deliveries from the Consortium on Safe Labor (2002-2008), obstetric and neonatal outcomes were compared for women with type 1 diabetes (n=507) and women without autoimmune disease (n=204,384). Preconception, trimester, and whole pregnancy average air pollutant exposure (ozone (O3), carbon monoxide (CO), particulate matter \u3e10 microns (PM10), PM \u3e2.5 microns (PM2.5), sulfur dioxide (SO2), nitrogen oxides (NOx)) were estimated using modified Community Multiscale Air Quality models. Poisson regression models with diabetes*pollutant interaction terms estimated relative risks and 95% confidence intervals for adverse outcomes, adjusted for maternal characteristics and geographic region. Results: For whole pregnancy exposure to SO2, women with type 1 diabetes had 15% increased risk (RR:1.15 95%CI:1.01,1.31) and women without autoimmune disease had 5% increased risk (RR:1.05 95%CI:1.05,1.06) for small for gestational age birth (pinteraction=0.09). Additionally, whole pregnancy O3 exposure was associated with 10% increased risk (RR:1.10 95%CI:1.02,1.17) among women with type 1 diabetes and 2% increased risk (RR:1.02 95%CI:1.00,1.04) among women without autoimmune disease for perinatal mortality (pinteraction=0.08). Similar patterns were observed between PM2.5 exposure and spontaneous preterm birth. Conclusions: Pregnant women with type 1 diabetes may be at greater risk for adverse outcomes when exposed to air pollution than women without autoimmune disease
Toward an optimal search strategy of optical and gravitational wave emissions from binary neutron star coalescence
Observations of an optical source coincident with gravitational wave emission
detected from a binary neutron star coalescence will improve the confidence of
detection, provide host galaxy localisation, and test models for the
progenitors of short gamma ray bursts. We employ optical observations of three
short gamma ray bursts, 050724, 050709, 051221, to estimate the detection rate
of a coordinated optical and gravitational wave search of neutron star mergers.
Model R-band optical afterglow light curves of these bursts that include a
jet-break are extrapolated for these sources at the sensitivity horizon of an
Advanced LIGO/Virgo network. Using optical sensitivity limits of three
telescopes, namely TAROT (m=18), Zadko (m=21) and an (8-10) meter class
telescope (m=26), we approximate detection rates and cadence times for imaging.
We find a median coincident detection rate of 4 yr^{-1} for the three bursts.
GRB 050724 like bursts, with wide opening jet angles, offer the most optimistic
rate of 13 coincident detections yr^{-1}, and would be detectable by Zadko up
to five days after the trigger. Late time imaging to m=26 could detect off-axis
afterglows for GRB 051221 like bursts several months after the trigger. For a
broad distribution of beaming angles, the optimal strategy for identifying the
optical emissions triggered by gravitational wave detectors is rapid response
searches with robotic telescopes followed by deeper imaging at later times if
an afterglow is not detected within several days of the trigger.Comment: 6 pages, 1 figure, Accepted for publication in MNRAS Letters (2011
April 22
- …