7,259 research outputs found
Lead and uranium group abundances in cosmic rays
The importance of Lead and Uranium group abundances in cosmic rays is discussed in understanding their evolution and propagation. The electronic detectors can provide good charge resolution but poor data statistics. The plastic detectors can provide somewhat better statistics but charge resolution deteriorates. The extraterrestrial crystals can provide good statistics but with poor charge resolution. Recent studies of extraterrestrial crystals regarding their calibration to accelerated uranium ion beam and track etch kinetics are discussed. It is hoped that a charge resolution of two charge units can be achieved provided an additional parameter is taken into account. The prospects to study abundances of Lead group, Uranium group and superheavy element in extraterrestrial crystals are discussed, and usefulness of these studies in the light of studies with electronic and plastic detectors is assessed
BVRI CCD photometric standards in the field of GRB 990123
The CCD magnitudes in Johnson and Cousins photometric passbands are
determined for 18 stars in the field of GRB 990123. These measurements can be
used in carrying out precise CCD photometry of the optical transient of GRB
990123 using differential photometric techniques during non--photometric sky
conditions. A comparison with previous photometry indicates that the present
photmetry is more precise.Comment: Tex file, 5 pages with 1 figure. Bull. Astron. Society India, Vol. 27
(accepted
Higher-Order Gravitational Lensing Reconstruction using Feynman Diagrams
We develop a method for calculating the correlation structure of the Cosmic
Microwave Background (CMB) using Feynman diagrams, when the CMB has been
modified by gravitational lensing, Faraday rotation, patchy reionization, or
other distorting effects. This method is used to calculate the bias of the
Hu-Okamoto quadratic estimator in reconstructing the lensing power spectrum up
to O(\phi^4) in the lensing potential . We consider both the diagonal
noise TTTT, EBEB, etc. and, for the first time, the off-diagonal noise TTTE,
TBEB, etc. The previously noted large O(\phi^4) term in the second order noise
is identified to come from a particular class of diagrams. It can be
significantly reduced by a reorganization of the expansion. These
improved estimators have almost no bias for the off-diagonal case involving
only one component of the CMB, such as EEEB.Comment: 17 pages, 17 figure
Gravitational Lensing of the CMB: a Feynman Diagram Approach
We develop a Feynman diagram approach to calculating correlations of the
Cosmic Microwave Background (CMB) in the presence of distortions. As one
application, we focus on CMB distortions due to gravitational lensing by Large
Scale Structure (LSS). We study the Hu-Okamoto quadratic estimator for
extracting lensing from the CMB and derive the noise of the estimator up to
in the lensing potential . The previously noted
large term can be significantly reduced by a
reorganization of the expansion. Our approach makes it simple to obtain
expressions for quadratic estimators based on any CMB channel. We briefly
discuss other applications to cosmology of this diagrammatic approach, such as
distortions of the CMB due to patchy reionization, or due to Faraday rotation
from primordial axion fields.Comment: 5 pages, 8 figures, v2: journal versio
A REVIEW ON “DRY SYRUPS FOR PAEDIATRICS”
Suspensions may be defined as preparations containing finely divided drug particles (the suspensoid) distributed somewhat uniformly throughout a vehicle with or without stabilizers and other additives in which drug exhibits a minimum degree of solubility hence conventional oral suspension can be administered immediately (ready to use form) and not requiring reconstitution at the time of dispensing are simply designated as “Oral Suspension”.
There is an important category of suspension that are available as dry powders intended for suspension in liquid vehicles. These are dry mixtures containing the drug and suitable suspending and dispersing agents to be diluted and agitated with a specific quantity of vehicle, most often purified water. Drugs that are instable if maintained for extended periods in the presence of aqueous vehicle (eg., many antibiotic drugs) are frequently supplied as dry powder mixtures for reconstitution at the time of dispensing. This type of preparation is designated in the USP by a title “for Oral Suspension”. The reconstituted system is the formulation of choice when the drug stability is a major concern. After reconstitution, these systems have a short but acceptable life if stored at refrigerator temperatures. Reconstitutable oral systems show the adequate chemical stability of the drug during shelf life, avoids the physical stability problems related to solubility, pH and incompatibilities with other ingredients and also reduce the weight of the final product because the aqueous vehicle is absent and consequently the transportation expenses may be reduced.
Dry syrup form of the drug is also useful in case of bioavailability as it has high bioavailability rather than tablets and capsules as it disintegrates in water outside of the oral cavity and directly the suspension is gone through the gastrointestinal tract. So the suspension easily absorbs in the GIT.
A number of commercial and official preparations are available as dry powder mixtures. The present review gives an account of the excipients used, methods of preparation of dry syrups along with their evaluations, their packaging, examples of research articles, few marketed preparations
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