743 research outputs found
Survey of Fungi in Foodstuffs Stored in ASC Warehouses in Assam Region
The paper describes the isolation and characterisation of various fungi present in common foodstuffs stored in Army warehouses located in hot humid climate of Assam. Fungal contamination in the food commodities is highest in the rainy season and lowest in winter. Among the fungi isolated, Aspergillus niger, A. Fumigatus, Rhizopus nigricans and species of Mucor and Penicillium were found in all the samples analysed. Amongst these, members of Aspergillus dominated in the rainy season and Penicillium. Rhizopus nigricans was predominant in the winter months
Night sky at the Indian Astronomical Observatory during 2000-2008
We present an analysis of the optical night sky brightness and extinction
coefficient measurements in UBVRI at the Indian Astronomical Observatory (IAO),
Hanle, during the period 2003-2008. They are obtained from an analysis of CCD
images acquired at the 2 m Himalayan Chandra Telescope at IAO. Night sky
brightness was estimated using 210 HFOSC images obtained on 47 nights and
covering the declining phase of solar activity cycle-23. The zenith corrected
values of the moonless night sky brightness in mag/square arcsecs are 22.14(U),
22.42(B), 21.28(V), 20.54(R) and 18.86(I) band. This shows that IAO is a dark
site for optical observations. No clear dependency of sky brightness with solar
activity is found. Extinction values at IAO are derived from an analysis of
1325 images over 58 nights. They are found to be 0.36 in U-band, 0.21 in
B-band, 0.12 in V-band, 0.09 in R-band and 0.05 in I-band. On average,
extinction during the summer months is slightly larger than that during the
winter months. No clear evidence for a correlation between extinction in all
bands and the average night time wind speed is found. Also presented here is
the low resolution moonless optical night sky spectrum for IAO covering the
wavelength range 3000-9300 \AA. Hanle region thus has the required
characteristics of a good astronomical site in terms of night sky brightness
and extinction, and could be a natural candidate site for any future large
aperture Indian optical-infrared telescope(s).Comment: 18 pages, 7 figures, uses basi.cls, accepted for publication in
Bulletin of the Astronomical Society of Indi
Optical observations of the bright long duration peculiar GRB 021004 afterglow
The CCD magnitudes in Johnson and Cousins and photometric
passbands are determined for the bright long duration GRB 021004 afterglow from
2002 October 4 to 16 starting 3 hours after the ray burst.
Light curves of the afterglow emission in ,, and passbands are
obtained by combining these measurements with other published data. The
earliest optical emission appears to originate in a revese shock. Flux decay of
the afterglow shows a very uncommon variation relative to other well-observed
GRBs. Rapid light variations, especially during early times (
days) is superposed on an underlying broken power law decay typical of a jetted
afterglow. The flux decay constants at early and late times derived from least
square fits to the light curve are and respectively,
with a jet break at around 7 day. Comparison with a standard fireball model
indicates a total extinction of mag in the direction of the
burst. Our low-resolution spectra corrected for this extinction provide a
spectral slope . This value and the flux decay constants
agree well with the electron energy index used in the model. The
derived jet opening angle of about implies a total emitted
gamma-ray energy erg at a cosmological distance
of about 20 Gpc. Multiwavelength observations indicate association of this GRB
with a star forming region, supporting the case for collapsar origin of long
duration GRBs.Comment: 19 pages, 3 figures, BASI, 31, 1
Cost-Effectiveness Model Shows Superiority of Wireless Spinal Cord Stimulation Implantation Without a Separate Trial.
OBJECTIVE: We evaluated the cost-effectiveness of wireless spinal cord stimulation (Wireless SCS) with single stage direct to permanent implantation vs. screening with temporary electrodes and an external pulse generator followed by implantation of a system for long-term use (IPG SCS).
MATERIALS AND METHODS: We created a cost model that takes a 2019 United States (U.S.) payer perspective and is based on IPG SCS cost models for subjects with chronic back and/or leg pain. Our six-month decision tree includes the screening trial period (success ≥50% relief) and leads to various levels of pain relief with or without complications for IPG SCS and Wireless SCS and without complications for conventional medical management (CMM). Every three months in the follow-on 15-year Markov model (with costs and quality-adjusted life years discounted 3.5% annually), subjects remain stable or transition to deteriorated health or death. Subjects who fail SCS receive CMM. After 60 Markov cycles, a 100,000-sample simulation reveals the impact of maximum willingness-to-pay (WTP) from 100,000 per quality-adjusted life year on net monetary benefit (NMB). Sensitivity analyses considered the impact of the Wireless SCS screening success rate, Wireless SCS device cost, and IPG SCS device longevity.
RESULTS: Compared with IPG SCS, Wireless SCS offers higher clinical effectiveness at a lower cost and a higher NMB for our WTP thresholds and is, thus, dominant. Wireless SCS is also cost-effective compared with CMM. Results remain robust with 1) Wireless SCS screening success rates as low as 85% (dominant), 2) the cost of the Wireless SCS devices as high as $55,000 (cost-effective), and 3) IPG SCS devices lasting 12 years (dominant).
CONCLUSIONS: In this model, compared with IPG SCS or with CMM, Wireless SCS is a superior strategy
Thermal Time Scales in a Color Glass Condensate
In a model of relativistic heavy ion collisions wherein the unconfined
quark-gluon plasma is condensed into glass, we derive the Vogel-Fulcher-Tammann
cooling law. This law is well known to hold true in condensed matter glasses.
The high energy plasma is initially created in a very hot negative temperature
state and cools down to the Hagedorn glass temperature at an ever decreasing
rate. The cooling rate is largely determined by the QCD string tension derived
from hadronic Regge trajectories. The ultimately slow relaxation time is a
defining characteristic of a color glass condensate.Comment: 5 pages, ReVTeX format, nofigure
FLASHES Survey. I. Integral Field Spectroscopy of the CGM around 48 z ≃ 2.3–3.1 QSOs
We present the pilot study of the Fluorescent Lyman-Alpha Structures in High-z Environments Survey; the largest integral field spectroscopy survey to date of the circumgalactic medium at z = 2.3–3.1. We observed 48 quasar fields with the Palomar Cosmic Web Imager to an average (2σ) limiting surface brightness of 6 × 10⁻¹⁸ erg s⁻¹ cm⁻² arcsec⁻² (in a 1'' aperture and ~20 Å bandwidth). Extended H I Lyα emission is discovered around 37/48 of the observed quasars, ranging in projected radius from 14 to 55 proper kiloparsecs (pkpc), with one nebula exceeding 100 pkpc in effective diameter. The dimming-adjusted circularly averaged surface brightness profile peaks at 1 × 10⁻¹⁵ erg s⁻¹ cm⁻² arcsec⁻² at R⊥ ~ 20 pkpc and integrated luminosities range from 0.4 to 9.4 × 10⁴³ erg s⁻¹. The emission appears to have an eccentric morphology and an average covering factor of ~30%–40% at small radii. On average, the nebular spectra are redshifted with respect to both the systemic redshift and Lyα peak of the quasar spectrum. The integrated spectra of the nebulae mostly have single- or double-peaked profiles with global dispersions ranging from 143 to 708 km s⁻¹, though the individual Gaussian components of lines with complex shapes mostly have dispersions ≤400 km s⁻¹, and the flux-weighted velocity centroids of the lines vary by thousands of km s⁻¹ with respect to the QSO redshifts. Finally, the root-mean-square velocities of the nebulae are found to be consistent with those expected from gravitational motions in dark matter halos of mass Log₁₀(M_h[M⊙]) ≃ 12.2^(+0.7)_(-1.2). We compare these results to existing surveys at higher and lower redshift
Optical afterglow of the not so dark GRB 021211
We determine Johnson and Cousins photometric CCD magnitudes for
the afterglow of GRB 021211 during the first night after the GRB trigger. The
afterglow was very faint and would have been probably missed if no prompt
observation had been conducted. A fraction of the so-called ``dark'' GRBs may
thus be just ``optically dim'' and require very deep imaging to be detected.
The early-time optical light curve reported by other observers shows prompt
emission with properties similar to that of GRB 990123. Following this, the
afterglow emission from min to days after the burst is
characterized by an overall power-law decay with a slope in the
passband. We derive the value of spectral index in the optical to near-IR
region to be 0.60.2 during 0.13 to 0.8 day after the burst. The flux decay
constant and the spectral slope indicate that optical observations within a day
after the burst lies between cooling frequency and synchrotron maximum
frequency.Comment: 4 pages, 2 figures, A&A Letters, 408, L2
Post-Outburst Phase of McNeil's Nebula (V1647 Orionis)
We present a detailed study of the post-outburst phase of McNeil's nebula
(V1647 Ori) using optical B,V,R,I and NIR J,H,K photometric and low resolution
optical spectroscopic observations. The observations were carried out with the
HFOSC, NIRCAM, TIRCAM and NICMOS cameras on the 2m HCT and 1.2m PRL telescopes
during the period 2004 Feb-2005 Dec. The optical/NIR observations show a
general decline in brightness of the exciting source of McNeil's nebula (V1647
Ori). Our recent optical images show that V1647 Ori has faded by more than 3
mags since Feb 2004. The optical/NIR photometric data also show a significant
variation in the mags (Delta V = 0.78 mag, Delta R = 0.44 mag, Delta I = 0.21
mag, Delta J = 0.24 mag and Delta H = 0.20 mag) of V1647 Ori within a period of
one month, which is possibly undergoing a phase similar to eruptive variables,
like EXors or FUors. The optical spectra show a few features such as strong
Halpha emission with blue-shifted absorption and the CaII IR triplet (8498A,
8542A and 8662A) in emission. As compared to the period just after outburst,
there is a decrease in the depth and extent of the blue-shifted absorption
component, indicating a weakening in the powerful stellar wind. The presence of
the CaII IR triplet in emission confirms that V1647 Ori is a PMS star. The
long-term, post-outburst photometric observations of V1647 Ori suggest an EXor,
rather than an FUor event. An optical/IR comparison of the region surrounding
McNeil's nebula shows that the optical nebula is more widely and predominantly
extended to the north, whereas the IR nebula is relatively confined (dia ~ 60
arcsec), but definitely extended, to the south, too.Comment: 25 pages (4 figures in JPEG format), Accepted for the publication in
MNRAS. Preprint is also available at:
http://www.tifr.res.in/~ojha/McNeil.htm
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