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Multiflash whistlers in ELF-band observed at low latitude
Ashutosh K. Singh, K. K. Singh, S. B. Singh, A. K. Singh,Lalmani
Annales Geophysicae (ANGEO) , 2011,
Abstract: Multiflash whistler-like event in the ELF-band, observed during March 1998 at low latitude station Jammu, is reported. The most prominent feature of these events is the multiflash nature along with the decrease in frequency within a very short span of time resembling similar to terrestrial whistlers. The events have a significantly smaller time duration (0.5–3.5 s) than those reported earlier from high, mid and low latitudes and also display a diurnal maximum occurring around 09:30 h (IST). There have been similar reportings from other latitudes, but whistlers in the ELF-band with a multiflash nature along with a precursor emission have never been reported. Lightning seems to be the dominant source for the ELF whistlers reported here.
Ducted whistler-mode signals received at two widely spaced locations
M. A. Clilverd,N. R. Thomson,A. J. Smith
Annales Geophysicae (ANGEO) , 2003,
Abstract: Whistler-mode signals from a single VLF transmitter that have propagated in the same duct, have been observed simultaneously at Faraday, Antarctica (65°S, 64°W) and Dunedin, New Zealand (46°S, 171°E). The signals received have group-delay times that differ in the order of 10 ms, which can be explained by the differences in southern-hemisphere sub-ionospheric propagation time from duct exit region to receiver for the two sites. This difference has been used to determine the location of the duct exit region, with confirmation provided by arrival-bearing information from both sites. The whistler-mode signals typically occur one or two days after geomagnetic activity, with Kpgeq5. The sub-ionospheric-propagation model, LWPC, is used to estimate the whistler-mode power radiated from the duct exit region. These results are then combined with estimated loss values for ionospheric and ducted transmission to investigate the role of wave-particle amplification or absorption. On at least half of the events studied, plasmaspheric amplification of the signals appears to be needed to explain the observed whistler-mode signal strengths.
Spatial correlation between lightning strikes and whistler observations from Tihany, Hungary
J. ?ster,A. B. Collier,A. R.W. Hughes,L. G. Blomberg
South African Journal of Science , 2010, DOI: 10.4102/sajs.v105i5/6.98
Abstract: A whistler is a very low frequency (VLF) phenomenon that acquires its characteristics from dispersive propagation in the magnetosphere. Whistlers are derived from the intense VLF radiation produced in lightning strikes, which can travel great distances within the Earth-ionosphere waveguide (EIWG) before penetrating the ionosphere, and exciting a duct. Field-aligned ducts of enhanced plasma density guide the propagation from one hemisphere to the other. The location of the duct, relative to the strike that causes the whistler, is unknown. Whistler time series from Tihany, Hungary, have been cross-correlated with lightning data obtained from the World Wide Lightning Location Network (WWLLN). The results show that whistlers observed at Tihany originate mainly from lightning strikes in an area with a radius of approximately 1 000 km surrounding the magnetic conjugate point in the Indian Ocean just east of East London, South Africa. A clear diurnal distinction was seen in that the correlation is maximised when the whistler station and the source region are in darkness. This is believed to relate to the diurnal variation of the ionosphere, which becomes more transparent to VLF waves at night.
Intangible pressures in Jammu and Kashmir
Ankur Datta
Forced Migration Review , 2012,
Abstract: History, inheritance and uncertainty affect the experience of being male, young and displaced in Jammu and Kashmir. Displacement has upset their life-plans, and the gulf between their immediate reality and their aspirations is considerable.
Whistler intensities above thunderstorms
J. Fiser, J. Chum, G. Diendorfer, M. Parrot,O. Santolik
Annales Geophysicae (ANGEO) , 2010,
Abstract: We report a study of penetration of the VLF electromagnetic waves induced by lightning to the ionosphere. We compare the fractional hop whistlers recorded by the ICE experiment onboard the DEMETER satellite with lightning detected by the EUCLID detection network. To identify the fractional hop whistlers, we have developed software for automatic detection of the fractional-hop whistlers in the VLF spectrograms. This software provides the detection times of the fractional hop whistlers and the average amplitudes of these whistlers. Matching the lightning and whistler data, we find the pairs of causative lightning and corresponding whistler. Processing data from ~200 DEMETER passes over the European region we obtain a map of mean amplitudes of whistler electric field as a function of latitudinal and longitudinal difference between the location of the causative lightning and satellite magnetic footprint. We find that mean whistler amplitude monotonically decreases with horizontal distance up to ~1000 km from the lightning source. At larger distances, the mean whistler amplitude usually merges into the background noise and the whistlers become undetectable. The maximum of whistler intensities is shifted from the satellite magnetic footprint ~1° owing to the oblique propagation. The average amplitude of whistlers increases with the lightning current. At nighttime (late evening), the average amplitude of whistlers is about three times higher than during the daytime (late morning) for the same lightning current.
Aids in Jammu. An Epidemiological Profile
Parveen Kaur, Bella Mahajan, S.K. Verrma, Gurmeet Kaur, Sufhia Akhtra
JK Science : Journal of Medical Education & Research , 2000,
Abstract: IIIV seropositivity. in blood samples collected from AIDS suspect cases (ASC) and the anonymous unlinkedhigh risk groups. was assessed by using two or three screening tests based on different principles forconfirmation of the results. The HIV seropositivity was found to be high (9.4%) in the AIDS suspectcases and 0.9% in the unlinked anonymous high risk group of patients allending STD clinic. DistrictHospital. Gandhi agar, Jammu.
New results of investigations of whistler-mode chorus emissions
O. Santolík
Nonlinear Processes in Geophysics (NPG) , 2008,
Abstract: This review summarizes selected recent results obtained during investigation of whistler-mode chorus emissions in the Earth's magnetosphere. Special attention is paid to results published during the last five years, with a focus on the results of the CLUSTER project. The nonlinear nature of chorus emissions is demonstrated using both theoretical results and measurements. Selected areas of research on whistler-mode chorus are covered and the paper especially reports new results on substructure and amplitudes of chorus wave packets, on new observations of frequency differences of chorus wave packets at different points in space and on their possible interpretations, on results concerning determination of position and size of the source region of chorus, on recent observational and theoretical results which lead to improved description of propagation of chorus from its source, and, finally, on comparison of chorus measurements with corresponding values deduced from nonlinear theory and simulations.
PUBLIC LIBRARY SYSTEM IN JAMMU & KASHMIR: AN ASSESSMENT
ZAHID ASHRAF WANI
Trends in Information Management , 2006,
Abstract: The paper is an insight into public library system of Jammu & Kashmir from ancient to present times. It lists different initiatives undertaken and reports submitted to the Government from time to time. The study mainly assesses 34 public libraries for their operations, services, staff strength and infrastructure. KEYWORDS : Public Library System; Public Libraries — Jammu & Kashmir;
Pulmonary Resections - Jammu Experience
Arvind Kohli, Gurjit Singh, Anita Vig, Rajinder Singh, Satya Dev Gupta
JK Science : Journal of Medical Education & Research , 2005,
Abstract: Ten year registry of patients who underwent pulmonary resections at CTVS section of Govt MedicalCollege Jammu is being presented. The cohort consisted of 94 patients operated between1994-2004.Males outnumbered females in this series Most number (30/94) of patients presented in the 4thdecade. Etiology wise, Infective lung diseases were the leading causes leading to pulmonary resections,this included bronchiectasts with 32/94, chronic empyema in6/94 and middle lobe syndrome in onepatient. Lung tumors were the causative factors in 20 and post tuberculosis destroyed lung in 17cases. Two patients presented with intralobar lung sequestrations and one each with pulmonaryblastoma and teratoma. The spectrum of resections included right pneumonectomy in19/94 followedby right and left lower lobectomies in 18 each. Thirteen patients underwent left pneumonectomy, 7bilobectomy and 4 lingulectomy respectively. The mortality in our series was 6/94,20 patients hadwound infection, 9 had bronchopleural fistula and 3 postoperative space infections.3 patients werereexplored because of hemorrhage in immediate postoperative period. Diagnostic video assistedthoracoscopy has been started and was employed in 6 patients.
Theory and Simulations of Whistler Wave Propagation  [PDF]
Dastgeer Shaikh
Physics , 2008, DOI: 10.1017/S0022377808007198
Abstract: A linear theory of whistler wave is developed wihtin the paradigm of a two dimensional incompressible electron magnetohydrodynamics model. Exact analytic wave solutions are obtained for a small amplitude whistler wave that exhibit magnetic field topological structures consistent with the observations and our simulations in linear regime. In agreement with experiment, we find that the parallel group velocity of the wave is large compared to its perpendicular counterpart. Numerical simulations of collisional interactions demonstrate that the wave magnetic field either coalesces or repels depending upon the polarity of the associated current. In the nonlinear regime, our simulations demonstrate that the evolution of wave magnetic field is governed essentially by the nonlinear Hall force.
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