168 research outputs found
Is a step in the primordial spectral index favored by CMB data ?
A sudden small change in the second derivative of the inflaton potential can
result in a universal local feature in the spectrum of primordial perturbations
generated during inflation. The exact solution describing this feature
\cite{minu} is characterized by a step in the spectral index modulated by
characteristic oscillations and results in a large running of the spectral
index localized over a few e-folds of scale. In this paper we confront this
step-like feature with the 5 year WMAP results and demonstrate that it provides
a better fit to this data than a featureless initial spectrum. If such a
feature exists at all, then it should lie at sufficiently large scales corresponding to . The sign of
the effect is shown to correspond to the negative running of localized
near this scale. This feature could arise as a result of a
`mini-waterfall'-type fast second order phase transition experienced by an
auxiliary heavy field during inflation, in a model similar to hybrid inflation
(though for a different choice of parameters). If this is the case, then the
auxiliary field should be positively coupled to the inflaton.Comment: Several new results, figures and enhanced discussion. Main
conclusions unchanged. Matches the final version to be published in JCA
New Universal Local Feature in the Inflationary Perturbation Spectrum
A model is developed in which the inflaton potential experiences a sudden
small change in its second derivative (the effective mass of the inflaton). An
exact treatment demonstrates that the resulting density perturbation has a
quasi-flat power spectrum with a break in its slope (a step in n_s). The step
in the spectral index is modulated by characteristic oscillations and results
in large running of the spectral index localised over a few e-folds of scales.
A field-theoretic model giving rise to such behaviour of the inflationary
potential is based on a fast phase transition experienced by a second scalar
field weakly coupled to the inflaton. Such a transition is similar to that
which terminates inflation in the hybrid inflationary scenario. This scenario
suggests that the observed running of the spectral index in the WMAP data may
be caused by a fast second order phase transition which occurred during
inflation.Comment: 4 figures, matches the published versio
Literacy and Livelihood of Women Migrant Construction Workers: An Analytical Study
Migration is a demographic process that has been chronicled across world history. Even though various reasons have accelerated this process over the years, the dominant trend in internal migration during the 20th century has been the movement from rural to urban areas. The casual and unskilled workers who shift from one region to another, offering their services on a temporary or seasonal basis are considered migrant labourers. The 21st century has witnessed problems related to migration intensifying. Migrant labourers face hostility from local populations posing a great challenge for governments to maintain the welfare of these people. Unfavorable social, economic, and cultural conditions make their lives even worse. As a result, migrant workers are frequently deprived of their basic rights and benefits which they otherwise deserve. This results in mass exploitation of the migrant community. Hence, the present study explores the problems and challenges faced by migrant construction workers, specifically women, and their impact on various aspects of their lives. The study has been conducted among 200 women migrant construction workers in North Bangalore as per the convenience sampling method, and the collected data was analyzed with the help of statistical tools such as Factor analysis, Chi-Square Analysis, one-way ANOVA, Weighted Average Rank
Elevated levels of serum adenosine deaminase in type 2 diabetes mellitus patients
Background: Diabetes Mellitus (DM) is a metabolic disorder characterized by an absolute or relative deficiency of insulin and insulin resistance or both. Adenosine deaminase (ADA) is an enzyme, that catalyses the irreversible hydrolytic deamination of adenosine to uric acid. Since ADA activity is associated with T-lymphocyte activity and insulin resistance, in the present study, we measured serum ADA activity in type 2 Diabetes mellitus (T2DM) patients to evaluate the relationship between serum ADA activities with glycemic status.Methods: A total of 100 T2DM patients and controls were recruited for the study. Estimation of fasting plasma glucose (FPG), postprandial plasma glucose (PPG), HbA1c and fasting lipid profile was done. Serum ADA level was estimated by Colorimetric method. Statistical analysis of data was performed using the SPSS version 15.Results: ADA level was significantly higher (p<0.001) in patients with T2DM (45.5+4.6 U/L) than controls. A significant positive correlation was observed between serum ADA and HbA1c (r=0.585), FPG (r=0.495), PPG (0.387) and serum triglycerides (r=0.375) among subjects with T2DM but not among non-diabetic controls.Conclusions: In the present study, serum ADA activity in T2DM patients has been increased. High ADA activity reduces the glucose uptake into cells; therefore, insulin resistance is related to ADA activity
From the Spectrum to Inflation: A Second Order Inverse Formula for the General Slow-Roll Spectrum
We invert the second order, single field, general slow-roll formula for the
power spectrum, to obtain a second order formula for inflationary parameters in
terms of the primordial power spectrum
N,N′-(2,2′-Dithiodi-o-phenylene)bis(furan-2-carboxamide)
The reaction of 2,2′-dithiobis(benzenamine) with furan-2-carbonyl chloride produced the bis-amide title compound, C22H16N2O4S2, which, in the crystal, formed a helix; the structure consists of two planar furanoylbenzenamines related by an improper rotation of 96.3° about the S—S bond. The N-furanoylbenzenamine units are planar (maximum deviations = 0.316 and 0.132 Å). Each electron-deficient acylfuran stacks (centroid–centroid separations of the two pairs of π–π stacked aromatic rings are 3.918 and 3.953 Å) with the electron-rich benzenamine of the other N-furanoylbenzenamine unit, leading to a spiral structure. The conformation is stabilized by two bifurcated intramolecular N—H⋯(O,S) interactions
Variation in superconducting transition temperature due to tetragonal domains in two-dimensionally doped SrTiO<sub>3</sub>
Strontium titanate is a low-temperature, non-Bardeen-Cooper-Schrieffer
superconductor that superconducts to carrier concentrations lower than in any
other system and exhibits avoided ferroelectricity at low temperatures. Neither
the mechanism of superconductivity in strontium titanate nor the importance of
the structure and dielectric properties for the superconductivity are well
understood. We studied the effects of twin structure on superconductivity in a
5.5-nm-thick layer of niobium-doped SrTiO embedded in undoped
SrTiO. We used a scanning superconducting quantum interference device
susceptometer to image the local diamagnetic response of the sample as a
function of temperature. We observed regions that exhibited a superconducting
transition temperature 10% higher than the temperature at
which the sample was fully superconducting. The pattern of these regions varied
spatially in a manner characteristic of structural twin domains. Our results
emphasize that the anisotropic dielectric properties of SrTiO are
important for its superconductivity, and need to be considered in any theory of
the mechanism of the superconductivity.Comment: 14 pages, 11 figures, Supplemental Information available at
http://stanford.edu/group/moler/papers/Noad_STOsuperconductivity_SI.pd
Topological structure and dynamics of three-dimensional active nematics.
Topological structures are effective descriptors of the nonequilibrium dynamics of diverse many-body systems. For example, motile, point-like topological defects capture the salient features of two-dimensional active liquid crystals composed of energy-consuming anisotropic units. We dispersed force-generating microtubule bundles in a passive colloidal liquid crystal to form a three-dimensional active nematic. Light-sheet microscopy revealed the temporal evolution of the millimeter-scale structure of these active nematics with single-bundle resolution. The primary topological excitations are extended, charge-neutral disclination loops that undergo complex dynamics and recombination events. Our work suggests a framework for analyzing the nonequilibrium dynamics of bulk anisotropic systems as diverse as driven complex fluids, active metamaterials, biological tissues, and collections of robots or organisms
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