18,898 research outputs found
Cosmic ray density gradient and its dependence on the north-south asymmetry in solar activity
An analysis of the diurnal anisotropy on geomagnetically quiet days was performed using neutron monitor data at Deep River, Leeds, Rome and Tokyo, well distributed in latitude and longitude for the period 1964-79. The days were separated according to the polarity of IMF on that day. A significant difference in the amplitude and phase was found on towards and away polarity days, particularly during the years of high solar activity and large north-south asymmetry. These results (particularly time of maximum) on geomagnetically quiet days show some better relationship to the expected results as compared to the results obtained using all the days in a year
Relativistic superluminal radio jets in microquasars in our galaxy
We discuss the origin of superluminal radio jets in Black hole X-ray binaries
with relativistic radio jets in our Galaxy popularly known as microquasars. We
classify the relativistic superluminal jet according to the radio emission in
black hole X-ray binaries (transient or persistent) rather than the mass of the
companion. The black hole X-ray binaries with transient radio emission (mostly
LMXBs) produce superluminal jets with 1 when the accretion
rate, is high and the bolometric luminosity L
approaches the Eddington Luminosity, L. On the other hand, the black
hole X-ray binaries with persistent radio emission (mostly HMXBs) produce
superluminal jets with 1 at relatively low . We
specially discuss the case of V4641 Sgr, a HMXB with transient radio emission
which produces superluminal radio jets like in LMXBs.Comment: 6 pages, 2 figures,VI Microquasar Workshop: Microquasars and Beyond,
September 18-22, 2006, Como, Ital
An hp-Local Discontinuous Galerkin method for Parabolic\ud Integro-Differential Equations
In this article, a priori error analysis is discussed for an hp-local discontinuous Galerkin (LDG) approximation to a parabolic integro-differential equation. It is shown that the L2 -norm of the gradient and the L2 -norm of the potential are optimal in the discretizing parameter h and suboptimal in the degree of polynomial p. Due to the presence of the integral term, an introduction of an expanded mixed type Ritz-Volterra projection helps to achieve optimal estimates. Further, it is observed that a negative norm estimate of the gradient plays a crucial role in our convergence analysis. As in the elliptic case, similar results on order of convergence are established for the semidiscrete method after suitably modifying the numerical fluxes. The optimality of these theoretical results is tested in a series of numerical experiments on two dimensional domains
Electronic transport properties of intermediately coupled superconductors: PdTe2 and Cu0.04PdTe2
We have investigated the electrical resistivity, Seebeck coefficient and
thermal conductivity of PdTe2 and 4% Cu intercalated PdTe2 compounds.
Electrical resistivity for the compounds shows Bloch-Gruneisen type linear
temperature (T) dependence for 100 K < T < 480 K, and Fermi liquid behavior (~
T^2) below 50 K. Seebeck coefficient data exhibit strong competition between
Normal (N) and Umklapp (U) scattering processes at low T. Though our results
indicate the transfer of charge carriers to PdTe2 upon Cu intercalation, it is
difficult to discern any change in the Fermi surface of the compound by
Nordheim-Gorter plots. The estimated Fermi energies of the compounds are quite
comparable to good metals Cu, Ag and Au. The low T, thermal conductivity (k) of
the compounds is strongly dominated by the electronic contribution, and
exhibits a rare linear T dependence below 10 K. However, high T, k(T) shows
usual 1/T dependence, dominated by U scattering process. The electron phonon
coupling parameters, estimated from the low T, specific heat data and first
principle electronic structure calculations suggest that PdTe2 and Cu0.04PdTe2
are intermediately coupled superconductors.Comment: 18 pages, 6 figure
Determination of galactic cosmic ray latitudinal gradient using Earth based detectors
Using cosmic ray intensity data from the Deep River Neutron monitor and the relation between solar wind velocity and heliomagnetic latitude, an attempt is made to evaluate quantitatively the latitudinal gradient of cosmic ray intensity during the periods dominated by a two sector pattern. Assuming a constant orientation of the heliospheric current sheet on a time scale of the order of a year, a relationship is determined between cosmic ray intensity and heliomagnetic latitude
Superconductivity at 5.2 K in ZrTe3 polycrystals and the effect of Cu, Ag intercalation
We report the occurrence of superconductivity in polycrystalline samples of
ZrTe3 at 5.2 K temperature at ambient pressure. The superconducting state
coexists with the charge density wave (CDW) phase, which sets in at 63K. The
intercalation of Cu or Ag, does not have any bearing on the superconducting
transition temperature but suppresses the CDW state. The feature of CDW anomaly
in these compounds is clearly seen in the DC magnetization data. Resistivity
data is analysed to estimate the relative loss of carriers and reduction in the
nested Fermi surface area upon CDW formation in the ZrTe3 and the intercalated
compounds.Comment: 5 pages, 8 figure
Book Reviews: The Yoga of the Christ in the Gospel According to St. John
Two book reviews for Ravi Ravindra\u27s The Yoga of the Christ in the Gospel According to St. John
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