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UVIT observations of the star-forming ring in NGC 7252: Evidence of possible AGN feedback suppressing central star formation
Context. Some post-merger galaxies are known to undergo a starburst phase that quickly depletes the gas reservoir and turns it into a red-sequence galaxy, though the details are still unclear. Aims. Here we explore the pattern of recent star formation in the central region of the post-merger galaxy NGC 7252 using high-resolution ultraviolet (UV) images from the UVIT on ASTROSAT. Methods. The UVIT images with 1.2 and 1.4 arcsec resolution in the FUV and NUV are used to construct a FUV-NUV colour map of the central region. Results. The FUV-NUV pixel colour map for this canonical post-merger galaxy reveals a blue circumnuclear ring of diameter ?10?? (3.2 kpc) with bluer patches located over the ring. Based on a comparison to single stellar population models, we show that the ring is comprised of stellar populations with ages ? 300 Myr, with embedded star-forming clumps of younger age (? 150Myr). Conclusions. The suppressed star formation in the central region, along with the recent finding of a large amount of ionised gas, leads us to speculate that this ring may be connected to past feedback from a central super-massive black hole that has ionised the hydrogen gas in the central ?4?? ?1.3 kpc. ESO 2018. -
More insights into bar quenching: Multi-wavelength analysis of four barred galaxies
The underlying nature of the process of star formation quenching in the central regions of barred disc galaxies that is due to the action of stellar bar is not fully understood. We present a multi-wavelength study of four barred galaxies using the archival data from optical, ultraviolet, infrared, CO, and HI imaging data on star formation progression and stellar and gas distribution to better understand the process of bar quenching. We found that for three galaxies, the region between the nuclear or central sub-kiloparsec region and the end of the bar (bar region) is devoid of neutral and molecular hydrogen. While the detected neutral hydrogen is very negligible, we note that molecular hydrogen is present abundantly in the nuclear or central sub-kiloparsec regions of all four galaxies. The bar co-rotation radius is also devoid of recent star formation for three out of four galaxies. One galaxy shows significant molecular hydrogen along the bar, which might mean that the gas is still being funnelled to the centre by the action of the stellar bar. Significant star formation is also present along the bar co-rotation radius of this galaxy. The study presented here supports a scenario in which gas redistribution as a result of the action of stellar bar clears the bar region of fuel for further star formation and eventually leads to star formation quenching in the bar region. 2020 ESO. -
Insights on bar quenching from a multiwavelength analysis: The case of Messier 95
The physical processes related to the eect of bars in the quenching of star formation in the region between the nuclear/central subkiloparsec region and the ends of the bar (bar region) of spiral galaxies is not fully understood. It is hypothesized that the bar can either stabilize the gas against collapse, inhibiting star formation, or eciently consume all the available gas, leaving no fuel for further star formation.We present a multiwavelength study using the archival data of an early-type barred spiral galaxy, Messier 95, which shows signatures of suppressed star formation in the bar region. Using optical, ultraviolet (UV), infrared, CO, and HI imaging data we study the pattern of star formation progression and stellar/gas distribution, and try to provide insights into the process responsible for the observed pattern. The FUV NUV pixel colour map reveals a cavity devoid of UV flux in the bar region that matches the length of the bar, which is 4.2 kpc. The central nuclear region of the galaxy shows a blue colour clump and along the major axis of the stellar bar the colour progressively becomes redder. Based on a comparison to single stellar population models, we show that the region of galaxy along the major axis of the bar, unlike the region outside the bar, is comprised of stellar populations with ages 350 Myr; there is a star-forming clump in the centre of younger ages of 150 Myr. Interestingly the bar region is also devoid of neutral and molecular hydrogen but has an abundant molecular hydrogen present at the nuclear region of the galaxy. Our results are consistent with a picture in which the stellar bar in Messier 95 is redistributing the gas by funnelling gas inflows to nuclear region, thus making the bar region devoid of fuel for star formation. ESO 2019. -
GASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy
We report evidence for star formation quenching in the central 8.6 kpc region of the jellyfish galaxy JO201 that hosts an active galactic nucleus (AGN), while undergoing strong ram-pressure stripping. The ultraviolet imaging data of the galaxy disc reveal a region with reduced flux around the centre of the galaxy and a horse-shoe-shaped region with enhanced flux in the outer disc. The characterization of the ionization regions based on emission line diagnostic diagrams shows that the region of reduced flux seen in the ultraviolet is within the AGN-dominated area. The CO J2-1 map of the galaxy disc reveals a cavity in the central region. The image of the galaxy disc at redder wavelengths (9050-9250 reveals the presence of a stellar bar. The star formation rate map of the galaxy disc shows that the star formation suppression in the cavity occurred in the last few 108 yr. We present several lines of evidence supporting the scenario that suppression of star formation in the central region of the disc is most likely due to the feedback from the AGN. The observations reported here make JO201 a unique case of AGN feedback and environmental effects suppressing star formation in a spiral galaxy. 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. -
Significance of bar quenching in the global quenching of star formation
The suppression of star formation in the inner kiloparsec regions of barred disk galaxies due to the action of bars is known as bar quenching. We investigate here the significance of bar quenching in the global quenching of star formation in the barred galaxies and their transformation to passive galaxies in the local Universe. We do this by measuring the offset of quenched barred galaxies from star-forming main sequence galaxies in the star formation rate-stellar mass plane and comparing it with the length of the bar, which is considered as a proxy of bar quenching. We constructed the star formation rate-stellar mass plane of 2885 local Universe face-on strong barred disk galaxies (z< 0.06) identified by Galaxy Zoo. The barred disk galaxies studied here fall on the star formation main sequence relation with a significant scatter for galaxies above stellar mass 1010.2M. We found that 34.97% galaxies are within the intrinsic scatter (0.3 dex) of the main sequence relation, with a starburst population of 10.78% (above the 0.3 dex) and a quenched population of 54.25% (below the-0.3 dex) of the total barred disk galaxies in our sample. Significant neutral hydrogen (MHI > 109Mwith log MHI/M?-1.0 to-0.5) is detected in the quenched barred galaxies with a similar gas content to that of the star-forming barred galaxies. We found that the offset of the quenched barred galaxies from the main sequence relation is not dependent on the length of the stellar bar. This implies that the bar quenching may not contribute significantly to the global quenching of star formation in barred galaxies. However, this observed result could also be due to other factors such as the dissolution of bars over time after star formation quenching, the effect of other quenching processes acting simultaneously, and/or the effects of environment. ESO 2019. -
K shell X-ray intensity ratios and vacancy transfer probabilities of Fe, Ag, and Te following electron capture decay
The K shell X-ray photons of Fe, Ag, and Te following the electron capture decay of Co57, Cd109, and I125, respectively, were detected using Si(Li) detector coupled to PC-based 8k multichannel analyzer employing a simple method suggested earlier by our group. The calculated K shell X-ray intensity ratios and vacancy transfer probabilities for these elements are compared with the theoretical values predicted by Scofield and with others' experimental values obtained via photoionization. It is found that the A? to A? X-ray intensity ratio of Fe is lower by 4.0%, while that of Ag and Te are greater by 7.9% and 19.1%, respectively, from the theoretical values. These deviations may be attributed to the exchange interactions occurring between the 3p-3d shell electrons as well as the recoil effect of the nucleus due to neutrino emission. 2014 Published by NRC Research Press. -
Highly selective first order derivative spectrophotometric determination of osmium(VIII) using anthranilic acid as a chromogenic reagent
A simple, selective and sensitive spectrophotometric method has been developed for the determination of osmium(VIII) using anthranilic acid as a reagent in the presence of Triton X-100. The molar absorptivity and Sandells sensitivity of the violet coloured species are 3.03 104L mol-1cm-1 and 3.5 ng cm-2 respectively. Beers law is obeyed between 0.5-5.5 ?g mL-1 of Os(VIII) at 500 nm. The stoichiometry of the complex is found to be 1:2 (metal: ligand). Calibration graph for the first order derivative spectrophotometric determination of Os(VIII) is derived by measuring derivative amplitudes at 525 nm with a linear range 0.25-5.5 ?g mL-1. The detection limit and quantitation limit of first order derivative spectrophotometry are found to be 0.075 and 0.25 ?g mL-1, respectively.1 1The metal ions, which are normally associated with osmium in catalysts and alloy samples, do not interfere. The proposed method has been successfully applied for the trace level determination of osmium in various synthetic mixtures containing commonly associated metal ions and corresponding to the alloy composition. 2015, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved. -
Kidney Abnormalities Detection and Classification Using CNN-based Feature Extraction
The presents of noises degrade the quality of ultrasound images and diminishes the disease diagnosis accuracy. Thus, an effective automatic stone and cyst detection system is beneficial to both the medical practitioners and patients. In this paper, an automatic detection and classification system for kidney stone and cyst image is proposed. The Gaussian filtering and Contrast Limited Adaptive Histogram Equalization (CLHE) techniques are applied to improve the quality of the images. In the next step, segmentation has been done based on the entropy of the image. The gamma correction technique has been applied to improve the overall brightness and an optimal global threshold value is selected to extract the region. The CNN model has attained much attention in medical image recognition and classification. In this paper, the pre-trained model ResNet-50 is utilized as a feature-extractor and Support Vector Machine as classifier to categorize the normal, cyst and stone images. The CNN model is analyzed with various other classification models such as k-nearest neighbor, decision tree and Nae Bayes. The results demonstrate that the ResNet-50 with supervised classification algorithm SVM is an optimal solution for analyzing kidney diseases. 2022 IEEE. -
Analysis of Kidney Ultrasound Images Using Deep Learning and Machine Learning Techniques: A Review
Ultrasonography is the most accepted and widely used imaging technique due to its non-invasive and radiation-free nature. The heterogeneous structure of kidney makes the disease detection a difficult task. Hence, more efficient models and methods are required to assist radiologists in making precise decisions. Since ultrasound imaging is considered to be the initial step in the diagnosis, more efficient processing techniques are needed in the interpretation of images. The presence of speckle noise is a challenge task in image processing. It diminishes the clarity of the images. In this article, an in-depth review has been performed on various machine learning and deep learning techniques, which are helping to improve the quality of images. The pre-processing, segmentation, feature extraction, and classification are described in detail using kidney cyst, stone, tumor, and normal kidney images. Deep learning techniques are enhancing the quality of the images with better accuracy. The remaining challenges and directions for future research are also explored. 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. -
Entropy Based Segmentation Model for Kidney Stone and Cyst on Ultrasound Image
Segmentation of abnormal masses in kidney images is a tough task. One of the main challenges is the presence of speckle noise, which will restrain the valuable information for the medical practitioners. Hence, the detection and segmentation of the affected regions vary in accuracies. The proposed model includes pre-processing and segmentation of the diseased region. The pre-processing consists of Gaussian filtering and Contrast Limited Adaptive Histogram Equalization (CLHE) to improve the clarity of the images. Further, segmentation has been done based on the entropy of the image and gamma correction has been done to improve the overall brightness of the images. An optimal global threshold value is selected to extract the region of interest and measures the area. The model is analyzed with statistical parameters like Jaccard index and Dice coefficient and compared with the ground truth images. To check the accuracy of the segmentation, relative error is calculated. This framework can be used by radiologists in diagnosing kidney patients. 2022, International Journal of Computing. All Rights Reserved. -
Dielectric performance of solid dielectric immersed in vegetable oil with antioxidant
Transformers are the most vital part of the power transmission and distribution system. Protecting them from all possible abnormalities is of very high priority. The insulation levels in the transformers need to be of very high grade as the power and voltage levels of a transformer are very high. Transformers are generally filled with petroleum based mineral oil as an insulator and also as a coolant inside them. These oils are highly inflammable and also highly toxic. They are also non-biodegradable, causing major harm to the environment. Vegetable oils which are abundant in nature unlike the mineral oil is being studied as a suitable substitute for mineral oils as transformer oil. The availability of vegetable oils differ from place to place. The work here focusses on the commercially available vegetable oils in India. Seven different samples of oil are tested for their dielectric properties and viscosity and the best one among them is tested with a solid dielectric (epoxy) immersed within it in order to simulate more appropriate conditions of a practical transformer. The tests are conducted based on Indian Standards (IS6792). 2016 IEEE. -
IDENTITIES AT THE DINNER TABLE: COMMENSALITY, SELF-PERCEPTION, AND RELATIONSHIPS IN ANNE CHERIANS A GOOD INDIAN WIFE
Food studies is rapidly gaining ground as a multidisciplinary area of research. Within it, literary food studies brings an interdisciplinary perspective as works of literature are viewed through the lens of food that is informed by frameworks and concepts that are rooted in a variety of fields including cultural anthropology, sociology, and more. one such concept that is in focus here is that of commensality that is associated with food and food practices. Commensality, drawing from notions of conviviality, refers to the practice of sharing a table and consuming food together. Deeper meanings of communal identities come to the fore in this social practice, leading it to shape how identities are understood and projected. Commensality can be a complex site of belonging and alienation depending on the context, and this paper seeks to explore the representation of the same in Anne Cherians A Good Indian Wife (2008). Leila, the titular Indian wife in the novel, moves to the US from India after her marriage to Neel and grapples with finding her place in the foreign land. With this displacement comes the endeavor to reaffirm her new identity, which now includes the role of being a wife and the aspect of being an immigrant. Neel also deals with complicated feelings towards the projection of his identity. With food playing a crucial role in the everyday experiences of their lives, commensality becomes a point of enquiry into how they see themselves and how their relationships with each other and themselves evolve through the course of the narrative. 2024 Nayana George. -
Consuming Identities in Foodways
[No abstract available] -
Commensality and Togetherness in Becky Chambers The Long Way to a Small, Angry Planet
Food in literature is always part of a symbolic act, as the characters within do not eat to stay alive as humans do, but rather, this depiction of eating is always a symbolic process. Food, especially in science fiction and fantasy fiction, works on an even grander scale by being an integral part of the world-building process. It operates on a two-fold scale by serving as a familiar anchor in futuristic and fantastical settings, while also functioning as a defamiliarizing agent that adds to the strangeness of the story world. Food is an incredibly complex motif to be explored in literature, but what will be concentrated on here is the aspect of commensality that is related to food and food practices. Commensality, often seen as related to conviviality, is the practice of sharing a table and consuming food together. This practice has connotations of the deeper meanings vested within food practices in a communal and social sense. These practices promote harmony and feelings of belongingness and togetherness. This paper looks at The Long Way to a Small, Angry Planet (2015) by Becky Chambers through the lens of food to explore how commensality works to create a home and promote the feeling of togetherness amongst an inter-galactic space crew that consists of multiple alien species from radically different cultures and communities. 2022, Istanbul University Press. All rights reserved. -
Exploring Cross-cultural Comfort Food Narratives in Beryl Shereshewskys YouTube Videos
This article explores how certain food and the stories linked to the same are capable of evoking feelings of comfort and security. Food binds people together. The rituals and practices surrounding food inspire and sustain the association of various memories, experiences and emotions. The area of food studies is especially interested in how these linkages translate into the practice of nourishment. The narratives surrounding comfort food take on a cross-cultural flavour in the videos from Beryl Shereshewskys YouTube channel. This article analyses these narratives through the lens of Symbolic Interactionism to explicate how these food narratives bring people together from across the world by evoking the universal needs of food and comfort. Consequently, it is seen that even though it is true that the experience of consuming comfort food is extremely personal, it is also rendered as a universal phenomenon through the narratives that are created and shared. 2023 MICA-The School of Ideas. -
Identity in Consumption: Reading Food and Intersectionality in Anita Desai's Fasting, Feasting
With the resurging interest in Food Studies, this rapidly emerging field of study has seen multiple disciplines adding in their distinct flavours that truly make this an area to savour. Literary food studies, in particular, has become a relevant field of study with the understanding that food in literature always plays a symbolic role, as food in literature is never depicted for the sustenance of the literary characters. This paper seeks to explore the novel Fasting, Feasting (1999) by Anita Desai through the lens of food and foodways to explicate how the characters interact with the culinary arena, and ultimately, interact with each other and themselves. These interactions will serve as crucial insights into their identities, particularly their intersectional gender identities considering the facets of nationality, class, and the like. A special focus will also be rendered on the notion of marginalisation seen in the text, of which gender is a crucial deciding factor. The title of the novel hints at consumption-at both its presence and absence-which will prove as the gateway to the interactions of the characters with food in the novel to examine who it is that gets to feast while who are forced to starve. 2022 Aesthetics Media Services. All rights reserved. -
Cryogenian magmatism and crustal reworking in the Southern Granulite Terrane, India
Understanding Neoproterozoic crustal evolution is fundamental to reconstructing the Gondwana supercontinent, which was assembled at this time. Here we report evidence of Cryogenian crustal reworking in the Madurai Block of the Southern Granulite Terrane of India. The study focuses on a garnet-bearing granite-charnockite suite, where the granite shows in situ dehydration into patches and veins of incipient charnockite along the contact with charnockite. The granite also carries dismembered layers of Mg-Al-rich granulite. Micro-textural evidence for dehydration of granite in the presence of CO2-rich fluids includes the formation of orthopyroxene by the breakdown of biotite, neoblastic zircon growth in the dehydration zone, at around 870C and 8 kbar. The zircon U-Pb ages suggest formation of the granite, charnockite, and incipient charnockite at 836 73, 831 31, and 772 49 Ma, respectively. Negative zircon ?Hf (t) (-5 to -20) values suggest that these rocks were derived from a reworked Palaeoproterozoic crustal source. Zircon grains in the Mg-Al-rich granulite record a spectrum of ages from ca. 2300 to ca. 500 Ma, suggesting multiple provenances ranging from Palaeoproterozoic to mid-Neoproterozoic, with neoblastic zircon growth during high-temperature metamorphism in the Cambrian. We propose that the garnet-bearing granite and charnockite reflect the crustal reworking of aluminous crustal material indicated by the presence of biotite + quartz + aluminosilicate inclusions in the garnet within the granite. This crustal source can be the Mg-Al-rich layers carried by the granite itself, which later experienced high-temperature regional metamorphism at ca. 550 Ma. Our model also envisages that the CO2 which dehydrated the garnet-bearing granite generating incipient charnockite was sourced from the proximal massive charnockite through advection. These Cryogenian crustal reworking events are related to prolonged tectonic activities prior to the final assembly of the Gondwana supercontinent. 2015 Taylor & Francis. -
Robs algorithm
Sparse matrix is a matrix having a relatively large proportion (proportion - a ratio is a comparison of two numbers. We generally separate the two numbers in the ratio with a colon (:)) of zero elements. To store the elements of the matrix in computer memory, linear array concept of storing is used. When a sparse matrix is stored in full-matrix storage mode, all its elements, including its zero elements, are stored in an array, which is a wastage of memory. In order to avoid the memory and processing overhead many alternate forms are used. Each one has separate time and space complexities and performances. In this paper we are suggesting one way of representing the sparse matrix which has both time and space complexity O(2n) only, while all other methods work with complexity more than O(3n) where n is the total number of non-zero elements in the matrix .The implementation of this algorithm in applications may improve the performance especially in the area of adjacency matrix, tree representation, 3D representation to an object, network communication, electronics, mathematical calculations, picture storage/file storage, file compression, bioinformatics, and the computer performance. The proposed algorithm has a large scope not only in computing but also in different branches of science, electronics and graphics. 2006 Elsevier Inc. All rights reserved. -
Humour as a moderator of stress and defence based coping mechanisms among the youth of Kerala, India
The goal of this study was to examine the effect of the moderators of adaptive and maladaptive humour on stress and on the four levels of defence based coping mechanism amongst the youth of Kerala, India. Four hundred and fifty-three youth between the age of 18 and 40, selected from two different cities of North Kerala, India (Calicut, Malappuram) and Central Kerala, India (Cochin, Trissur), were asked to fill out three questionnaires assessing stress, coping and humour. Pearson's test of product-moment correlation indicated that stress had a positive and moderate statistically significant correlation with the first three levels of defence based coping mechanism (pathological defences, immature defences and neurotic defences). Furthermore, there was a positive and weak statistically significant correlation between stress and level-IV coping (mature defences). When positive and moderate correlation was found for stress with maladaptive humour, no significant correlation was found with adaptive humour. When coping was studied in relationship with humour, a negative and weak statistically significant correlation was found for level-I coping (pathological defences) with adaptive humour, whereas a positive and moderate statistically significant correlation was found with maladaptive humour. Here level-IV coping (mature defences) was found to have a positive and moderate statistically significant relationship with adaptive and maladaptive humour. Moderator analysis showed that maladaptive humour moderated the association between stress and four levels of defence based coping mechanism. The study implied that youth should be trained to use more of mature means of coping and adaptive humour styles in life. Universiti Putra Malaysia Press