843 research outputs found
Increased incidence of glomerulonephritis following spleno-renal shunt surgery in non-cirrhotic portal fibrosis
Increased incidence of glomerulonephritis following spleno-renal shunt surgery in non-cirrhotic portal fibrosis. In a prospective study of 200 non-cirrhotic portal fibrosis (NCPF) patients, 7% had mild proteinuria and their renal biopsies showed mild mesangial proliferative glomerulonephritis (mes-PGN). The remaining 93% biopsies were normal. However, following the insertion of a spleno-renal shunt (SRS) for portal hypertension 32% of these patients developed nephrotic syndrome in five years. Renal histology revealed mesangiocapillary glomerulonephritis (MCGN) (18.5%), mes-PGN (9%), minimal change nephropathy (3%), and chronic sclerosing GN (1.5%). Immunofluorescence showed granular deposition of IgA and C3. IgA2 was the predominant form of Ig in the glomerular deposits, indicating that IgA in the immune complexes was derived from the gastrointestinal tract. Electron microscopy revealed electron dense deposits in the mesangium. In contrast to the NCPF patients who underwent a SRS for portal hypertension, the 200 patients in our study who underwent spleno-renal shunting because of extra hepatic portal obstruction did not have renal disease, nor did they develop renal disease during the five-year post-operative follow-up. Fifty percent of the glomerulonephritis (GN) in the NCPF group progressed to renal failure in five years; 46.6% continued to have proteinuria. Low serum complement, C3 (40%) and circulating immune complexes (14.8%) were detected in the glomerulonephritis group. Our study shows that: (i) there is a high rate of the occurrence of GN following SRS in NCPF patients, but not in those with normal livers; (ii) the type of GN is primarily IgA nephropathy; and (iii) the GN could be the result of defective hepatic reticuloendothelial function in the NCPF group that is worsened by the shunting procedure
Aerosol Chemistry over a High Altitude Station at Northeastern Himalayas, India
BACKGROUND: There is an urgent need for an improved understanding of the sources, distributions and properties of atmospheric aerosol in order to control the atmospheric pollution over northeastern Himalayas where rising anthropogenic interferences from rapid urbanization and development is becoming an increasing concern. METHODOLOGY/PRINCIPAL FINDINGS: An extensive aerosol sampling program was conducted in Darjeeling (altitude approximately 2200 meter above sea level (masl), latitude 27 degrees 01'N and longitude 88 degrees 15'E), a high altitude station in northeastern Himalayas, during January-December 2005. Samples were collected using a respirable dust sampler and a fine dust sampler simultaneously. Ion chromatograph was used to analyze the water soluble ionic species of aerosol. The average concentrations of fine and coarse mode aerosol were found to be 29.5+/-20.8 microg m(-3) and 19.6+/-11.1 microg m(-3) respectively. Fine mode aerosol dominated during dry seasons and coarse mode aerosol dominated during monsoon. Nitrate existed as NH(4)NO(3) in fine mode aerosol during winter and as NaNO(3) in coarse mode aerosol during monsoon. Gas phase photochemical oxidation of SO(2) during premonsoon and aqueous phase oxidation during winter and postmonsoon were the major pathways for the formation of SO(4)(2-) in the atmosphere. Long range transport of dust aerosol from arid regions of western India was observed during premonsoon. The acidity of fine mode aerosol was higher in dry seasons compared to monsoon whereas the coarse mode acidity was higher in monsoon compared to dry seasons. Biomass burning, vehicular emissions and dust particles were the major types of aerosol from local and continental regions whereas sea salt particles were the major types of aerosol from marine source regions. CONCLUSIONS/SIGNIFICANCE: The year-long data presented in this paper provide substantial improvements to the heretofore poor knowledge regarding aerosol chemistry over northeastern Himalayas, and should be useful to policy makers in making control strategies
Silkworm Thermal Biology: A Review of Heat Shock Response, Heat Shock Proteins and Heat Acclimation in the Domesticated Silkworm, Bombyx mori
Heat shock proteins (HSPs) are known to play ecological and evolutionary roles in this postgenomic era. Recent research suggests that HSPs are implicated in cardiovascular biology and disease development, proliferation and regulation of cancer cells, cell death via apoptosis, and several other key cellular functions. These activities have generated great interest amongst cell and molecular biologists, and these biologists are keen to unravel other hitherto unknown potential functions of this group of proteins. Consequently, the biological significance of HSPs has led to cloning and characterization of genes encoding HSPs in many organisms including the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae). However, most of the past investigations in B. mori were confined to expression of HSPs in tissues and cell lines, whereas information on their specific functional roles in biological, physiological, and molecular processes is scarce. Naturally occurring or domesticated polyvoltines (known to be the tropical race) are more resistant to high temperatures and diseases than bi- or univoltines (temperate races). The mechanism of ecological or evolutionary modification of HSPs during the course of domestication of B. mori - particularly in relation to thermotolerance in geographically distinct races/strains - is still unclear. In addition, the heat shock response, thermal acclimation, and hardening have not been studied extensively in B. mori compared to other organisms. Towards this, recent investigations on differential expression of HSPs at various stages of development, considering the concept of the whole organism, open ample scope to evaluate their biological and commercial importance in B. mori which has not been addressed in any of the representative organisms studied so far. Comparatively, heat shock response among different silkworm races/strains of poly-, bi-, and univoltines varies significantly and thermotolerance increases as the larval development proceeds. Hence, this being the first review in this area, an attempt has been made to collate all available information on the heat shock response, HSPs expression, associated genes, amino acid sequences, and acquired/unacquired thermotolerance. The aim is to present this as a valuable resource for addressing the gap in knowledge and understanding evolutionary significance of HSPs between domesticated (B. mori) and non-domesticated insects. It is believed that the information presented here will also help researchers/breeders to design appropriate strategies for developing novel strains for the tropics
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGOâs first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
Daksha: On Alert for High Energy Transients
We present Daksha, a proposed high energy transients mission for the study of
electromagnetic counterparts of gravitational wave sources, and gamma ray
bursts. Daksha will comprise of two satellites in low earth equatorial orbits,
on opposite sides of earth. Each satellite will carry three types of detectors
to cover the entire sky in an energy range from 1 keV to >1 MeV. Any transients
detected on-board will be announced publicly within minutes of discovery. All
photon data will be downloaded in ground station passes to obtain source
positions, spectra, and light curves. In addition, Daksha will address a wide
range of science cases including monitoring X-ray pulsars, studies of
magnetars, solar flares, searches for fast radio burst counterparts, routine
monitoring of bright persistent high energy sources, terrestrial gamma-ray
flashes, and probing primordial black hole abundances through lensing. In this
paper, we discuss the technical capabilities of Daksha, while the detailed
science case is discussed in a separate paper.Comment: 9 pages, 3 figures, 1 table. Additional information about the mission
is available at https://www.dakshasat.in
Science with the Daksha High Energy Transients Mission
We present the science case for the proposed Daksha high energy transients
mission. Daksha will comprise of two satellites covering the entire sky from
1~keV to ~MeV. The primary objectives of the mission are to discover and
characterize electromagnetic counterparts to gravitational wave source; and to
study Gamma Ray Bursts (GRBs). Daksha is a versatile all-sky monitor that can
address a wide variety of science cases. With its broadband spectral response,
high sensitivity, and continuous all-sky coverage, it will discover fainter and
rarer sources than any other existing or proposed mission. Daksha can make key
strides in GRB research with polarization studies, prompt soft spectroscopy,
and fine time-resolved spectral studies. Daksha will provide continuous
monitoring of X-ray pulsars. It will detect magnetar outbursts and high energy
counterparts to Fast Radio Bursts. Using Earth occultation to measure source
fluxes, the two satellites together will obtain daily flux measurements of
bright hard X-ray sources including active galactic nuclei, X-ray binaries, and
slow transients like Novae. Correlation studies between the two satellites can
be used to probe primordial black holes through lensing. Daksha will have a set
of detectors continuously pointing towards the Sun, providing excellent hard
X-ray monitoring data. Closer to home, the high sensitivity and time resolution
of Daksha can be leveraged for the characterization of Terrestrial Gamma-ray
Flashes.Comment: 19 pages, 7 figures. Submitted to ApJ. More details about the mission
at https://www.dakshasat.in
First measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo BinaryâBlack-hole Merger GW170814
International audienceWe present a multi-messenger measurement of the Hubble constant H 0 using the binaryâblack-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in , which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km sâ1 Mpcâ1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km sâ1 Mpcâ1, we find (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H 0
Erratum: âSearches for Gravitational Waves from Known Pulsars at Two Harmonics in 2015â2017 LIGO Dataâ (2019, ApJ, 879, 10)
Due to an error at the publisher, in the published article the number of pulsars presented in the paper is incorrect in multiple places throughout the text. Specifically, "222" pulsars should be "221." Additionally, the number of pulsars for which we have EM observations that fully overlap with O1 and O2 changes from "168" to "167." Elsewhere, in the machine-readable table of Table 1 and in Table 2, the row corresponding to pulsar J0952-0607 should be excised as well. Finally, in the caption for Table 2 the number of pulsars changes from "188" to "187.
Searches for gravitational waves from known pulsars at two harmonics in 2015-2017 LIGO data
International audienceWe present a search for gravitational waves from 222 pulsars with rotation frequencies âł10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015â2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsarâs rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = m = 2 mode search, we provide updated upper limits on the gravitational-wave amplitude, mass quadrupole moment, and fiducial ellipticity for 167 pulsars, and the first such limits for a further 55. For 20 young pulsars these results give limits that are below those inferred from the pulsarsâ spin-down. For the Crab and Vela pulsars our results constrain gravitational-wave emission to account for less than 0.017% and 0.18% of the spin-down luminosity, respectively. For the recycled millisecond pulsar J0711â6830 our limits are only a factor of 1.3 above the spin-down limit, assuming the canonical value of 1038 kg m2 for the starâs moment of inertia, and imply a gravitational-wave-derived upper limit on the starâs ellipticity of 1.2 Ă 10â8. We also place new limits on the emission amplitude at the rotation frequency of the pulsars
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