Error Estimates for Measurements of Cosmic Shear

In the very near future, weak lensing surveys will map the projected density of the universe in an unbiased way over large regions of the sky. In order to interpret the results of studies it is helpful to develop an understanding of the errors associated with quantities extracted from the observations. In a generalization of one of our earlier works, we present estimators of the cumulants and cumulant correlators of the weak lensing convergence field, and compute the variance associated with these estimators. By restricting ourselves to so-called compensated filters we are able to derive quite simple expressions for the errors on these estimates. We also separate contributions from cosmic variance, shot noise and intrinsic ellipticity of the source galaxies.Comment: 12 pages, including 5 figures, uses mn.sty. Substantially revised version accepted by MNRA

From linear to non-linear scales: analytical and numerical predictions for the weak lensing convergence

Weak lensing convergence can be used directly to map and probe the dark mass distribution in the universe. Building on earlier studies, we recall how the statistics of the convergence field are related to the statistics of the underlying mass distribution, in particular to the many-body density correlations. We describe two model-independent approximations which provide two simple methods to compute the probability distribution function, pdf, of the convergence. We apply one of these to the case where the density field can be described by a log-normal pdf. Next, we discuss two hierarchical models for the high-order correlations which allow one to perform exact calculations and evaluate the previous approximations in such specific cases. Finally, we apply these methods to a very simple model for the evolution of the density field from linear to highly non-linear scales. Comparisons with the results obtained from numerical simulations, obtained from a number of different realizations, show excellent agreement with our theoretical predictions. We have probed various angular scales in the numerical work and considered sources at 14 different redshifts in each of two different cosmological scenarios, an open cosmology and a flat cosmology with non-zero cosmological constant. Our simulation technique employs computations of the full 3-d shear matrices along the line of sight from the source redshift to the observer and is complementary to more popular ray-tracing algorithms. Our results therefore provide a valuable cross-check for such complementary simulation techniques, as well as for our simple analytical model, from the linear to the highly non-linear regime.Comment: 20 pages, final version published in MNRA

Relativistic Expansion of Electron-Positron-Photon Plasma Droplets and Photon Emission

The expansion dynamics of hot electron-positron-photon plasma droplets is dealt with within relativistic hydrodynamics. Such droplets, envisaged to be created in future experiments by irradiating thin foils with counter-propagating ultra-intense laser beams, are sources of flashes of gamma radiation. Warm electron-positron plasma droplets may be identified and characterized by a broadened 511 keV line

Application of laparoscopy in current fertility practice

Background: The present study is carried out with the objective of establishing the role of diagnostic and operative laparoscopy as a simple, safe and accurate tool in the evaluation of infertility. The aims of current study were to study the application of laparoscopy in current fertility practice, to evaluate indications for diagnostic laparoscopy for infertility, to study findings of diagnostic laparoscopy and to study various operative procedures performed for correction of infertility.Methods: This is a prospective study of 50 women undergoing infertility workup in a private hospital from January 2011 to January 2012. All infertile women having primary or secondary infertility were included in the study. Couples having male factor infertility were excluded from the study. Data were collected and analyzed.Results: Our study is conducted in 50 cases of infertility patients out of which 74% were primary infertility and 26% were secondary infertility. Uterine factors were found in 16% of cases, tubal factors were found in 44% of cases, ovarian factors were implicated in 30% of cases out of which majority (12%) had PCOD. Among the peritoneal factors (18%) endometriosis and pelvic adhesions were found in 6% each. Inspite of thorough laparoscopic evaluation no cause (unexplained infertility) was found in 14% of cases and hence overall, the pelvic pathology was found in 86% of cases.Conclusions: Laparoscopy is the gold standard for diagnosing tubal and peritoneal disease, endometriosis, adhesions and other pelvic pathology, because no other imaging technique provides the same degree of sensitivity and specificity

Study of 50 cases of modern management of ectopic pregnancy

Background: In recent years, an increased incidence of ectopic gestation has been noted, which can be attributed to different reasons. Cases with ectopic gestation were studied and objectives were to study the incidence in various age groups, to study predisposing factors, to study different modes of clinical presentation, to study different sites of ectopic pregnancy and to study changing trends of modern management from radical surgical method to laparoscopic and medical management.Methods: A study of 50 cases of tubal ectopic pregnancy was carried out from May 2009 to June 2011 in tertiary health centre. Patients managed with following treatment modalities were selected for study. (1) Medical management (MTX), (2) Laparoscopic management: salpingostomy, salpingectomy, (3) Laparotomy management: salpingostomy, segmental resection, fimbrial expression, salpingectomy.Results: Lower abdominal pain was most common presenting symptom of ectopic pregnancy in 96% cases. The classical triad of symptoms (amenorrhea, abdominal pain and vaginal bleeding) was present in only 28% cases. PID contributed 24% cases and previous abortion contributed 28% cases indicating these two as the common risk factors. Ampulla was the commonest site for ectopic pregnancy, in 52% cases. Salpingostomy performed mainly at this site. In 6% cases ectopic pregnancy in infundibulum were treated with fimbrial expression and fimbriectomy. 22% patients were managed medically (methotraxte). These were the cases having unruptured ectopic pregnancy and ectopic mass <4 cm. Laparoscopy was done in 34% cases, in 2 cases it was converted to laparotomy. While open laparotomy was done in 40% cases.Conclusions: Ectopic pregnancy is a treatable problem. Ultrasonography plays central role in the diagnosis and management. Mode of therapy is determined by a combination of clinical symptoms, sonography findings and serum b-HCG values. Surgical management is still a cornerstone of management of ectopic pregnancy. But now scope of medical and laparoscopic management is also there. In recent years laparotomy has been replaced by laparoscopic surgery which is more conservative, minimally invasive and less time consuming which leads to quick recovery

New approaches to probing Minkowski functionals

We generalize the concept of the ordinary skew-spectrum to probe the effect of non-Gaussianity on the morphology of cosmic microwave background (CMB) maps in several domains: in real space (where they are commonly known as cumulant-correlators), and in harmonic and needlet bases. The essential aim is to retain more information than normally contained in these statistics, in order to assist in determining the source of any measured non-Gaussianity, in the same spirit as Munshi & Heavens skew-spectra were used to identify foreground contaminants to the CMB bispectrum in Planck data. Using a perturbative series to construct the Minkowski functionals (MFs), we provide a pseudo-C based approach in both harmonic and needlet representations to estimate these spectra in the presence of a mask and inhomogeneous noise. Assuming homogeneous noise, we present approximate expressions for error covariance for the purpose of joint estimation of these spectra. We present specific results for four different models of primordial non-Gaussianity local, equilateral, orthogonal and enfolded models, as well as non-Gaussianity caused by unsubtracted point sources. Closed form results of nextorder corrections to MFs too are obtained in terms of a quadruplet of kurt-spectra. We also use the method of modal decomposition of the bispectrum and trispectrum to reconstruct the MFs as an alternative method of reconstruction of morphological properties of CMB maps. Finally, we introduce the odd-parity skew-spectra to probe the odd-parity bispectrum and its impact on the morphology of the CMB sky. Although developed for the CMB, the generic results obtained here can be useful in other areas of cosmology

Measurements of Three Dimensional Temperature Field in Fluids using Laser Interferometry

Non-intrusive measurement of fluid temperature using laser interferometry is reported. As a case study, results obtained in Rayleigh-Benard convection experiment are presented. Image processing operations required for the evaluation interferograms and extraction of quantitative data from the optical Images are discussed. Limited-view tomographic algorithms applicable to interferometry are discussed and compared in terms of reconstructed three-dimensional temperature fields. This study concludes that laser interferometry coupled with tomography promises a versatile tool for three-dimensional temperature and flow field measurements in fluids

Image Reconstruction from Incomplete Projection Data using Combined ART- CBP Algorithm

The present work is concerned with reconstructing cross-sections of composite structures when complete projection data is not available from the experiments. A novel approach combining the algebraic reconstruction technique (ART) and convolution back projection (CBP) algorithm has been developed for reconstruction with such data. The numerical results obtained reveal that a combination of ART and CBP is able to reconstruct cross-sections from incomplete data to an extent that is meaningful for non-destructive evaluation

Galaxy clustering in 3D and modified gravity theories

We study Modified Gravity (MG) theories by modelling the redshifted matter power spectrum in a spherical Fourier-Bessel (sFB) basis. We use a fully non-linear description of the real-space matter power-spectrum and include the lowest-order redshift-space correction (Kaiser effect), taking into account some additional non-linear contributions. Ignoring relativistic corrections, which are not expected to play an important role for a shallow survey, we analyse two different modified gravity scenarios, namely the generalised Dilaton scalar-tensor theories and the f(R) models in the large curvature regime. We compute the 3D power spectrum C s ℓ (k 1 ,k 2 ) for various such MG theories with and without redshift space distortions, assuming precise knowledge of background cosmological parameters. Using an all-sky spectroscopic survey with Gaussian selection function φ(r)∝exp(−r 2 /r 2 0 ) , r 0 =150h −1 Mpc , and number density of galaxies N ¯ =10 −4 Mpc −3 , we use a χ 2 analysis, and find that the lower-order (ℓ≤25) multipoles of C s ℓ (k,k ′ ) (with radial modes restricted to k25 modes can further reduce the error bars and thus in principle make cosmological gravity constraints competitive with solar system tests. However this will require an accurate modelling of non-linear redshift space distortions. Using a tomographic β(a) -m(a) parameterization we also derive constraints on specific parameters describing the Dilaton models of modified gravity