EXPLORING THE X-RAY UNIVERSE IN THE MICROCALORIMETER ERA

Next-generation microcalorimeter missions like XRISM and Athena will revolutionize X-ray spectroscopy by offering a plethora of high-resolution X-ray spectra. Interpreting these observations requires a complete understanding of how matter interacts with light through such microphysical processes as absorption and excitation. I developed a framework describing the atomic processes for both collisionally-ionized and photoionized plasmas over a wide range of column densities. Through various line-intensity and line-ratio spectral diagnostics, I established four asymptotic limits; Cases A, B, C, and D. These apply to the formation of lines in H- and He-like systems. This is the first work describing these limits in the X-ray regime. I discussed line optical depth effects in H- and He-like iron with applications to the Hitomi observations of hot gas in the Perseus cluster of galaxies. I introduced a novel method of measuring column density using the Case A to B (optically thin to thick) transition by comparing the observed spectra by Hitomi with spectra simulated with the spectral synthesis code Cloudy. I explored the effects of Li-like iron on the Fe XXV Kα line intensities through Resonant Auger Destruction (RAD) and line broadening effects by electron scattering. These methods are now in place and will be available to the community by the launch of the XRISM mission

Diversity in Hybridity: A Quest for (Re)Locating the Self in Kaushik Barua's Windhorse

Every ethnic group has a unique identity as an essential element of their existence – an identity which evolves anthropologically, culturally and topologically. While for the members of a diaspora community the very identity becomes further crucial for the existence and for their functioning in discrete cultural/political/social milieu of foreign countries. The notion of identity plays the pivotal role in the lives of displaced communities, as it prevents them from assimilation and acculturation. This paper on Kaushik Barua’s Windhorse would attempt to illustrate the plurality of identity present among individuals of the Tibetan diasporic community, scattered over different parts of India. The paper would also seek to throw light on its diverse manifestations, evolution, alteration and adoption. It would also aim at interrogating the role of identity, as one of the constitutive parameters of ‘nationalism’, deftly portrayed through the movement and their participation in it. The paper scrutinizes the life and experience of three young Tibetans bringing them on same temporal and spatial scale, thereby, making them interact with each other while carrying forward their own personal as well as cultural paraphernalia

Mean Occupation Function of High Redshift Quasars from the Planck Cluster Catalog

We characterise the distribution of quasars within dark matter halos using a direct measurement technique for the first time at redshifts as high as $z \sim 1$. Using the Planck Sunyaev-Zeldovich (SZ) catalogue for galaxy groups and the Sloan Digital Sky Survey (SDSS) DR12 quasar dataset, we assign host clusters/groups to the quasars and make a measurement of the mean number of quasars within dark matter halos as a function of halo mass. We find that a simple power-law fit of \log\left = (2.11 \pm 0.01) \log (M) -(32.77 \pm 0.11) can be used to model the quasar fraction in dark matter halos. This suggests that the quasar fraction increases monotonically as a function of halo mass even to redshifts as high as $z\sim 1$.Comment: Accepted for publication in PAS

Cladocera as a substitute for Artemia as live feed in aquaculture practices: a review.

Rearing larval forms of fishes is a crucial and critical step in aquaculture practices. Proper nurturing of juvenile forms is important to ensure their survival and growth. Supplementary feeds have been used long since to augment growth and productivity of fishes throughout the world. Despite, availability of a variety of advanced artificial feeds, zooplanktons have been preferred over artificial feeds for their qualities like: better digestibility, nutritional levels, preference by fish larvae and economic feasibility, especially for rearing young fin and shell fish species. Conventionally, Artemia sp. (brine shrimps) has been preferred among live feed organisms for rearing of fish larvae, but, applicability of cladocerans has been less explored despite their several beneficial features. Studies have reported most cladocerans species (especially, Moina sp. and Daphnia sp.) are nutritionally rich comprising of a variety of essential fatty acids, amino acids, digestive enzymes and micronutrients etc. Being an important component of trophic structure in water bodies, they form a link between different trophic levels through food chain relationships, ensuring nutrient dynamics. Their small size and jerky movements make them attractive to larval fish forms. Moreover, their cost effective culture process can thus be an efficient, feasible, economical and sustainable alternative to comparatively costlier and less abundant Artemia feed. This article endeavours to review and highlight the efficiency of cladocerans over Artemia feed for providing a viable and sustainable diet in commercial aquaculture practice.La cría de formas larvarias de peces es un paso crucial y crítico en las prácticas de acuicultura. La crianza adecuada de las formas juveniles es importante para asegurar su supervivencia y crecimiento. Los alimentos complementarios se han utilizado desde hace mucho tiempo para aumentar el crecimiento y la productividad de los peces en todo el mundo. A pesar de la disponibilidad de una variedad de alimentos artificiales avanzados, se ha preferido el zooplancton a los alimentos artificiales por sus cualidades como: mejor digestibilidad, niveles nutricionales, preferencia por larvas de peces y viabilidad económica, especialmente para la cría de especies jóvenes de aletas y mariscos. Convencionalmente, Artemia sp. (camarones de salmuera) se ha preferido entre los organismos de alimento vivo para la cría de larvas de peces, pero la aplicabilidad de los cladóceros se ha explorado menos a pesar de sus diversas características beneficiosas. Los estudios han informado que la mayoría de las especies de cladóceros (especialmente, Moina sp. Y Daphnia sp.) Son nutricionalmente ricas y comprenden una variedad de ácidos grasos esenciales, aminoácidos, enzimas digestivas y micronutrientes, etc. Al ser un componente importante de la estructura trófica en los cuerpos de agua, Formar un vínculo entre diferentes niveles tróficos a través de las relaciones de la cadena alimentaria, asegurando la dinámica de los nutrientes. Su pequeño tamaño y movimientos espasmódicos los hacen atractivos para las larvas de peces. Además, su proceso de cultivo rentable puede ser una alternativa eficiente, factible, económica y sostenible a los piensos de Artemia comparativamente más costosos y menos abundantes. Este artículo intenta revisar y resaltar la eficiencia de los cladóceros sobre el alimento de Artemia para proporcionar una dieta viable y sostenible en la práctica de la acuicultura comercial

Biofeedback: Can it be used as an Assessment Tool?

Biofeedback forms an integral part of Complementary and Alternate Medicine (CAM). It acts as a self-regulation technique through which individuals voluntarily learn to control what they believe are involuntary body processes. It records physiological signals using sensors and converts them into meaningful visual and auditory cues that provide feedback about physiological responses through a computer screen. It has been widely used as an intervention tool since the time of its development. The utility and effectiveness of biofeedback are not only restricted to illness but also to enhancing health and well-being. The biofeedback mechanism relies on two primary principles: Psychophysiological Mechanism and Operant Conditioning Mechanism. Applying the same mechanisms, biofeedback can also be used as an assessment tool. It may be used in research studies to assess the efficacy of a particular intervention at various data points and also be used in clinical practice to assess the improvement in the patient, which in turn will be a self-reinforcement for the patient. Thus, research in biofeedback as an assessment tool besides an effective intervention measure is warranted in both clinical studies and pure theoretical research

New resonance scattering model in AtomDB: application to line suppression in galaxy clusters and elliptical galaxies

In this paper, we present a simple, one-step, self-consistent, and fast resonance scattering model rsapec based on the AtomDB database. This model can be used as an alternative to the commonly used APEC model for fitting such X-ray spectra with optically thick lines. The current model is intended, in general, for verifying the presence of the effect and for spectral modeling of galaxy clusters and elliptical galaxies under applicable assumptions. We test rsapec to derive the line suppression in the elliptical galaxy NGC 4636 and the Perseus cluster of galaxies and obtain resonance suppression of ~ 1.24 and ~ 1.30, respectively.Comment: Accepted for publication in Ap

Evidence of a Sub-Saturn around EPIC~211945201

We report here strong evidence for a sub-Saturn around EPIC~211945201 and confirm its planetary nature. EPIC~211945201b was found to be a planetary candidate from {\it K2} photometry in Campaigns 5 \& 16, transiting a bright star ($V_{\rm mag}=10.15$, G0 spectral type) in a 19.492 day orbit. However, the photometric data combined with false positive probability calculations using VESPA was not sufficient to confirm the planetary scenario. Here we present high-resolution spectroscopic follow-up of the target using the PARAS spectrograph (19 radial velocity observations) over a time-baseline of 420 days. We conclusively rule out the possibility of an eclipsing binary system and confirm the 2-$\sigma$ detection of a sub-Saturn planet. The confirmed planet has a radius of 6.12$\pm0.1$$~R_{\oplus}$, and a mass of $27_{-12.6}^{+14}$~$M_{\oplus}$. We also place an upper limit on the mass (within the 3-$\sigma$ confidence interval) at 42~$M_{\oplus}$ above the nominal value. This results in the Saturn-like density of $0.65_{-0.30}^{+0.34}$ g~cm$^{-3}$. Based on the mass and radius, we provide a preliminary model-dependent estimate that the heavy element content is 60-70 \% of the total mass. This detection is important as it adds to a sparse catalog of confirmed exoplanets with masses between 10-70 $M_{\oplus}$ and radii between 4-8 $R_{\oplus}$, whose masses and radii are measured to a precision of 50\% or better (only 23 including this work).Comment: Accepted for publication in The Astronomical Journal, 17 pages, 8 figure