Simultaneous X-ray and optical observations of thermonuclear bursts in the LMXB EXO 0748-676

We report the detection of a large number of optical bursts in the Low Mass X-ray Binary (LMXB) EXO 0748-676 simultaneous with the thermonuclear X-ray bursts. The X-ray and the optical bursts are detected in a long observation of this source with the XMM-Newton observatory. This has increased the number of thermonuclear X-ray bursts in the LMXBs with simultaneous optical detection by several factors. The optical bursts are found to have a linear rise followed by a slow, somewhat exponential decay. Most of the optical bursts have longer rise and decay timescale compared to the corresponding X-ray bursts. We have determined the X-ray and optical excess photon counts in the bursts that allow us to look at the optical to X-ray burst fluence ratio for each burst and the ratio as a function of the X-ray burst intensity and as a function of the orbital phase. The delay between the onset of the X-ray bursts and the onset of the optical bursts have also been measured and is found to have an average value of 3.25 seconds. We do not find any convincing evidence of orbital phase dependence of the following parameters: X-ray to optical delay, rise time of the optical bursts, and optical to X-ray burst intensity ratio as would be expected if the optical bursts were produced by reprocessing from the surface of the secondary star that is facing the compact star. On the other hand, if the optical bursts are produced by reprocessing of the X-rays in the accretion disk, the onset of the bursts is not expected to have a sharp, linear shape as is observed in a few of the bursts in EXO 0748-676. We emphasise the fact that simultaneous optical observations of the X-ray bursts in multiple wavelength bands will enable further detailed investigations of the reprocessing phenomena, including any non-linear effect of the X-ray irradiation.Comment: 12 pares, 5 figures (Submitted to the Bulletin of the Astronomical Society of India

Exploring Short-GRB afterglow parameter space for observations in coincidence with gravitational waves

Short duration Gamma Ray Bursts(SGRB) and their afterglows are among the most promising electro-magnetic (EM) counterparts of Neutron Star (NS) mergers. The afterglow emission is broadband, visible across the entire electro-magnetic window from $\gamma$-ray to radio frequencies. The flux evolution in these frequencies is sensitive to the multi-dimensional afterglow physical parameter space. Observations of gravitational wave (GW) from BNS mergers in spatial and temporal coincidence with SGRB and associated afterglows can provide valuable constraints on afterglow physics. We run simulations of GW-detected BNS events and assuming all of them are associated with a GRB jet which also produces an afterglow, investigate how detections or non-detections in X-ray, optical and radio frequencies can be influenced by the parameter space. We narrow-down the regions of afterglow parameter space for a uniform top-hat jet model which would result in different detection scenarios. We list inferences which can be drawn on the physics of GRB afterglows from multi-messenger astronomy with coincident GW-EM observations.Comment: Published in MNRA

Rates of Short-GRB afterglows in association with Binary Neutron Star mergers

Assuming all binary Neutron Star mergers produce Short Gamma Ray Bursts (SGRBs), we combine the merger rates of binary Neutron Stars (BNS) from population synthesis studies, the sensitivities of advanced Gravitational Wave (GW) interferometer networks, and of the electromagnetic (EM) facilities in various wave bands, to compute the detection rate of associated afterglows in these bands. Using the inclination angle measured from GWs as a proxy for the viewing angle and assuming a uniform distribution of jet opening angle between 3 to 30 degrees, we generate light curves of the counterparts using the open access afterglow hydrodynamics package BoxFit for X-ray, Optical and Radio bands. For different EM detectors we obtain the fraction of EM counterparts detectable in these three bands by imposing appropriate detection thresholds. In association with BNS mergers detected by five (three) detector network of advanced GW interferometers, assuming a BNS merger rate of $0.6-774{\rm Gpc}^{-3}{\rm yr}^{-1}$~\citep{dominik2012double}, we find the afterglow detection rates (per year) to be $0.04-53$ ($0.02-27$), $0.03-36$ ($0.01-19$) and $0.04-47$ ($0.02-25$) in the X-ray, optical and radio bands respectively. Our rates represent maximum possible detections for the given BNS rate since we ignore effects of cadence and field of view in EM follow up observations.Comment: Published in MNRA

Association between maternal serum beta human chorionic gonadotropin levels and hypertensive disorders of pregnancy

Background: A major challenge in obstetrics is early identification of hypertensive disorders of pregnancy (HDP). This study was performed to determine the association between elevated maternal serum β-hCG levels and HDP, the correlation between serum β-hCG level and severity of preeclampsia and to determine the value of serum β-hCG level as a diagnostic marker for early diagnosis of HDP.Methods: This was a hospital based observational study conducted in the department of obstetrics and gynecology, Rajendra Institute of Medical Sciences, Ranchi on 375 pregnant women with period of gestation more than 20 weeks, including 250 pregnant women with HDP as study group and 125 normotensive pregnant women as controls. Serum β-hCG concentration was measured and its level was compared between two groups.Results: The maternal mean serum β-hCG levels (51161.08±30038.21 IU/L) of study group of HDP were higher than the normotensive control group (17603.23±16748.21 IU/L). In non-severe preeclampsia, the mean serum levels were 36417.32±23876.74 IU/L while in severe preeclampsia, 60030.34±28771.31 IU/L. There was statistically significant difference (p<0.001) with higher levels in early onset preeclamptic mothers than late onset preeclampsia. The cut-off point of β-hCG for predicting HDP was 32077 IU/L with sensitivity of 65% and specificity of 86%.Conclusions: Serum β-hCG level is higher in HDP when compared to normotensive women. Higher levels of β-hCG are associated with increasing severity of hypertensive disorders of pregnancy. The utility of serum β-hCG as a diagnostic test is limited because of low sensitivity and difficulty in deciding the cut-off value

Implementation of low-loss superinductances for quantum circuits

The simultaneous suppression of charge fluctuations and offsets is crucial for preserving quantum coherence in devices exploiting large quantum fluctuations of the superconducting phase. This requires an environment with both extremely low DC and high RF impedance. Such an environment is provided by a superinductance, defined as a zero DC resistance inductance whose impedance exceeds the resistance quantum $R_Q = h/(2e)^2 \simeq 6.5\ \mathrm{k\Omega}$ at frequencies of interest (1 - 10 GHz). In addition, the superinductance must have as little dissipation as possible, and possess a self-resonant frequency well above frequencies of interest. The kinetic inductance of an array of Josephson junctions is an ideal candidate to implement the superinductance provided its phase slip rate is sufficiently low. We successfully implemented such an array using large Josephson junctions ($E_J >> E_C$), and measured internal losses less than 20 ppm, self-resonant frequencies greater than 10 GHz, and phase slip rates less than 1 mHz

Non-degenerate, three-wave mixing with the Josephson ring modulator

The Josephson ring modulator (JRM) is a device, based on Josephson tunnel junctions, capable of performing non-degenerate mixing in the microwave regime without losses. The generic scattering matrix of the device is calculated by solving coupled quantum Langevin equations. Its form shows that the device can achieve quantum-limited noise performance both as an amplifier and a mixer. Fundamental limitations on simultaneous optimization of performance metrics like gain, bandwidth and dynamic range (including the effect of pump depletion) are discussed. We also present three possible integrations of the JRM as the active medium in a different electromagnetic environment. The resulting circuits, named Josephson parametric converters (JPC), are discussed in detail, and experimental data on their dynamic range are found to be in good agreement with theoretical predictions. We also discuss future prospects and requisite optimization of JPC as a preamplifier for qubit readout applications.Comment: 21 pages, 16 figures, 4 table

Effect of different potato varieties and tuber sizes on physiological changes under ambient storage performance

The storability and sprouting behavior of three grades (small, medium and large tubers) from four Indian potato cultivars was studied under ambient conditions to assess the quality changes due to physiological losses and sprouting bhaviour of potato tubers. It was found that physiological loss in weight (%), decay loss on number and weight basis (%), sprout loss on number and weight basis (%), total loss (%), general appearance, presence of black or hollow heart were affected significantly by the different varieties as well as by the size. The loss in weight of tubers due to physiological activities, decaying and sprouting increased with the increased in storage period and the loss was more in larger than smaller and medium tubers. Kufri Badshah showed the best control over sprouting, whereas, 100% sprouting was observed in Kufri Bahar with all possible combinations during storage. The maximum value for cumulative physiological loss in weight was observed in variety Kufri Bahar (12.07%), whereas, minimum was in Kufri Pushkar (7.44%). The maximum decay loss was observed in variety Kufri Pushkar (7.89 and 8.72%) and minimum in Kufri Bahar (0.00 and 4.58%) on 80th and 90th day of storage period. Black or hollow heart was absent completely in all the possible treatments. So far general appearance of the tubers was concerned, the larger tubers shrivelled more and earlier than the medium and small sized tubers. Different varieties behaved differently during the entire storage period

Dental fear in children and its relation to dental caries and gingival condition – a cross sectional study in Bangalore City, India.

Aims and objectives: The aim of this study was to determine the levels of dental fear, and its association with dental caries and gingivitis among 12 &ndash; 15 year old government high school children in Bangalore City, India. Methods: Eight government high schools were selected by simple random method from the 2 zones of Bangalore City. All the children who participated in this study were asked the single item Dental Anxiety Question to assess the dental fear and underwent oral examination for dental caries and gingivitis using decayed, missing and filled teeth (DMFT) index and Community Periodontal Index (CPI), respectively. Results: The prevalence of high dental fear among the study population was 23.4%. The mean MT was significantly associated with high fear. Highly significant correlation was found between presence of bleeding on gentle probing and high dental fear. Conclusion: High dental fear plays an important role in the oral health status of 12 to 15 year old children.&nbsp

Anterior and Posterior Tongue Regions and Taste Papillae: Distinct Roles and Regulatory Mechanisms with an Emphasis on Hedgehog Signaling and Antagonism.

Sensory receptors across the entire tongue are engaged during eating. However, the tongue has distinctive regions with taste (fungiform and circumvallate) and non-taste (filiform) organs that are composed of specialized epithelia, connective tissues, and innervation. The tissue regions and papillae are adapted in form and function for taste and somatosensation associated with eating. It follows that homeostasis and regeneration of distinctive papillae and taste buds with particular functional roles require tailored molecular pathways. Nonetheless, in the chemosensory field, generalizations are often made between mechanisms that regulate anterior tongue fungiform and posterior circumvallate taste papillae, without a clear distinction that highlights the singular taste cell types and receptors in the papillae. We compare and contrast signaling regulation in the tongue and emphasize the Hedgehog pathway and antagonists as prime examples of signaling differences in anterior and posterior taste and non-taste papillae. Only with more attention to the roles and regulatory signals for different taste cells in distinct tongue regions can optimal treatments for taste dysfunctions be designed. In summary, if tissues are studied from one tongue region only, with associated specialized gustatory and non-gustatory organs, an incomplete and potentially misleading picture will emerge of how lingual sensory systems are involved in eating and altered in disease