9,531 research outputs found
Primordial Non-Gaussianity in the Cosmic Microwave Background
In the last few decades, advances in observational cosmology have given us a
standard model of cosmology. We know the content of the universe to within a
few percent. With more ambitious experiments on the way, we hope to move beyond
the knowledge of what the universe is made of, to why the universe is the way
it is. In this review paper we focus on primordial non-Gaussianity as a probe
of the physics of the dynamics of the universe at the very earliest moments. We
discuss 1) theoretical predictions from inflationary models and their
observational consequences in the cosmic microwave background (CMB)
anisotropies; 2) CMB--based estimators for constraining primordial
non-Gaussianity with an emphasis on bispectrum templates; 3) current
constraints on non-Gaussianity and what we can hope to achieve in the near
future; and 4) non-primordial sources of non-Gaussianities in the CMB such as
bispectrum due to second order effects, three way cross-correlation between
primary-lensing-secondary CMB, and possible instrumental effects.Comment: 27 pages, 8 figures; Invited Review for the Journal "Advances in
Astronomy"; references adde
Optimal error estimates of a mixed finite element method for\ud parabolic integro-differential equations with non smooth initial data
In this article, a new mixed method is proposed and analyzed for parabolic integro-differential equations (PIDE) with nonsmooth initial data. Compared to mixed methods for PIDE, the present method does not bank on a reformulation using a resolvent operator. Based on energy arguments and without using parabolic type duality technique, optimal L2-error estimates are derived for semidiscrete approximations, when the initial data is in L2. Due to the presence of the integral term, it is, further, observed that estimate in dual of H(div)-space plays a role in our error analysis. Moreover, the proposed analysis follows the spirit of the proof technique used for deriving optimal error estimates of finite element approximations to PIDE with smooth data and therefore, it unifies both the theories, i.e., one for smooth data and other for nonsmooth data. Finally, the proposed analysis can be easily extended to other mixed method for PIDE with rough initial data and provides an improved result
Orthogonal Ramanujan Sums, its properties and Applications in Multiresolution Analysis
Signal processing community has recently shown interest in Ramanujan sums
which was defined by S.Ramanujan in 1918. In this paper we have proposed
Orthog- onal Ramanujan Sums (ORS) based on Ramanujan sums. In this paper we
present two novel application of ORS. Firstly a new representation of a finite
length signal is given using ORS which is defined as Orthogonal Ramanujan
Periodic Transform.Secondly ORS has been applied to multiresolution analysis
and it is shown that Haar transform is a spe- cial case
Effect of pressure cycling on Iron: Signatures of an electronic instability and unconventional superconductivity
High pressure electrical resistivity and x-ray diffraction experiments have
been performed on Fe single crystals. The crystallographic investigation
provides direct evidence that in the martensitic
transition at 14 GPa the become the directions. During a pressure cycle, resistivity shows a
broad hysteresis of 6.5 GPa, whereas superconductivity, observed between 13 and
31 GPa, remains unaffected. Upon increasing pressure an electronic instability,
probably a quantum critical point, is observed at around 19 GPa and, close to
this pressure, the superconducting and the isothermal resistivity
(K) attain maximum values. In the superconducting pressure domain,
the exponent of the temperature power law of resistivity and its
prefactor, which mimics , indicate that ferromagnetic fluctuations may
provide the glue for the Cooper pairs, yielding unconventional
superconductivity
CSPOB-Continuous Spectrophotometry of Black Holes
The goal of a small and dedicated satellite called the "Continuous
Spectro-Photometry of Black Holes" or CSPOB is to provide the essential tool
for the theoretical understanding of the hydrodynamic and magneto-hydrodynamic
flows around black holes. In its life time of about three to four years, only a
half a dozen black holes will be observed continuously with a pair of CSPOBs.
Changes in the spectral and temporal variability properties of the high-energy
emission would be caught as they happen. Several important questions are
expected to be answered and many puzzles would be sorted out with this mission.Comment: 4 Pages, 3 Figures, Proceeding of the 2nd Kolkata Conference on
"Observational Evidence for the Black Holes in the Universe", Published in
AIP, 200
Triplication of Deciduous Teeth: A Rare Dental Anomaly
Fusion of teeth is the union of two or more tooth germs, which are usually separated. Depending upon the stage of odontogenesis, it can be complete or incomplete. The present case describes fusion between the maxillary primary right central and lateral incisor with a supernumerary tooth. Clinical and radiographic examination revealed the presence of fused triple teeth. The fused teeth were extracted, sectioned and were visualized under stereomicroscope at three levels and the diagnosis of fusion of three teeth was confirmed histologically.Keywords: Fusion, primary teeth, supernumerary tooth, triple teet
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