Image Compression Using Neural Networks

Image compression is a well-studied field of Computer Vision. Recently, many neural network based architectures have been proposed for image compression as well as enhancement. These networks are also put to use by frameworks such as end-to-end image compression. In this project, we have explored the improvements that can be made over this framework to achieve better benchmarks in compressing images. Generative Adversarial Networks are used to generate new fake images which are very similar to original images. Single Image Super-Resolution Generative Adversarial Networks (SI-SRGAN) can be employed to improve image quality. Our proposed architecture can be divided into four parts : image compression module, arithmetic encoder, arithmetic decoder, image reconstruction module. This ar- chitecture is evaluated based on compression rate and the closeness of the reconstructed image to the original image. Structural similarity metrics and peak signal to noise ratio are used to evaluate the image quality. We have also measured the net reduction in file size after compression and compared it with other lossy image compression techniques. We have achieved better results in terms of these metrics compared to legacy and newly proposed image compression algorithms. In particular, an average PSNR of 28.48 and SSIM value of 0.86 is achieved as compared to 28.45 PSNR and 0.81 SSIM value in end to end image compression framework [1

Modelling the AM CVn and Double Detonation Supernova Progenitor Binary System CD-30∘^{\circ}11223

We present a detailed modelling study of CD-30$^{\circ}$11223 (CD-30), a hot subdwarf (sdB)-white dwarf (WD) binary identified as a double detonation supernova progenitor, using the open-source stellar evolution software MESA. We focus on implementing binary evolution models carefully tuned to match the observed characteristics of the system including $\log g$ and $T_{\rm eff}$. For the first time, we account for the structure of the hydrogen envelope throughout the modelling, and find that the inclusion of element diffusion is important for matching the observed radius and temperature. We investigate the two sdB mass solutions (0.47 and 0.54 $M_{\odot}$) previously proposed for this system, strongly favouring the 0.47 $M_{\odot}$ solution. The WD cooling age is compared against the sdB age using our models, which suggest an sdB likely older than the WD, contrary to the standard assumption for compact sdB-WD binaries. Subsequently, we propose a possible alternate formation channel for CD-30. We also perform binary evolution modelling of the system to study various aspects such as mass transfer, orbital period evolution and luminosity evolution. Our models confirm CD-30 as a double detonation supernova progenitor, expected to explode $\approx55$ Myr from now. The WD accretes a $\approx0.17$ $M_{\odot}$ thick helium shell that causes a detonation, leaving a 0.30 $M_{\odot}$ sdB ejected at $\approx$750 km/s. The final 15 Myr of the system are characterised by helium accretion which dominates the system luminosity, possibly resembling an AM CVn-type system.Comment: 12 pages, 8 figures. Accepted for publication in MNRA

Laparoscopic Removal of Pelvic Hydatid Cysts in Young Female: A Case Report

Hydatid disease is a zoonotic infection caused by larval stages of dog tapeworms belonging to the genus Echinococcus (family taeniidae) and is also referred to as echinococcosis. Human cystic echinococcosis caused by E. granulosus is the most common presentation and probably accounts for more than 95% of the estimated 2-3 million annual worldwide cases. The liver (70–80%) and lungs (15–25%) are the most frequent locations for echinococcal cysts. The diagnosis is made through the combined assessment of clinical, radiological, and laboratory findings. The treatment is mainly surgical, and, with appropriate diagnosis and treatment, prognosis is good. With advances and increasing experience in laparoscopic surgery, many more attempts have been made to offer the advantage of such a procedure to these patients (Chowbey et al. (2003))

The psychological toll of slum living in Mumbai, India: A mixed methods study

In India, “non-notified” slums are not officially recognized by city governments; they suffer from insecure tenure and poorer access to basic services than “notified” (government-recognized) slums. We conducted a study in a non-notified slum of about 12,000 people in Mumbai to determine the prevalence of individuals at high risk for having a common mental disorder (i.e., depression and anxiety), to ascertain the impact of mental health on the burden of functional impairment, and to assess the influence of the slum environment on mental health. We gathered qualitative data (six focus group discussions and 40 individual interviews in July-November 2011), with purposively sampled participants, and quantitative data (521 structured surveys in February 2012), with respondents selected using community-level random sampling. For the surveys, we administered the General Health Questionnaire-12 (GHQ) to screen for common mental disorders (CMDs), the WHO Disability Assessment Schedule 2.0 (WHO DAS) to screen for functional impairment, and a slum adversity questionnaire, which we used to create a composite Slum Adversity Index (SAI) score. Twenty-three percent of individuals have a GHQ score ≥5, suggesting they are at high risk for having a CMD. Psychological distress is a major contributor to the slum’s overall burden of functional impairment. In a multivariable logistic regression model, household income, poverty-related factors, and the SAI score all have strong independent associations with CMD risk. The qualitative findings suggest that non-notified status plays a central role in creating psychological distress—by creating and exacerbating deprivations that serve as sources of stress, by placing slum residents in an inherently antagonistic relationship with the government through the criminalization of basic needs, and by shaping a community identity built on a feeling of social exclusion from the rest of the city

Initial Visible and Mid-IR Characterization of P/2019 LD₂ (ATLAS), an Active Transitioning Centaur Among the Trojans, with Hubble, Spitzer, ZTF, Keck, APO and GROWTH Imaging and Spectroscopy

We present visible and mid-infrared imagery and photometry of Jovian co-orbital comet P/2019 LD₂ (ATLAS) taken with Hubble Space Telescope/WFC3 on 2020 April 1, Spitzer Space Telescope/IRAC on 2020 January 25, Zwicky Transient Facility between 2019 April 9 and 2019 Nov 8 and the GROWTH telescope network from 2020 May to July, as well as visible spectroscopy from Keck/LRIS on 2020 August 19. Our observations indicate that LD₂ has a nucleus with radius 0.2-1.8 km assuming a 0.08 albedo and that the coma is dominated by ∼100 μ m-scale dust ejected at ∼1 m/s speeds with a ∼1" jet pointing in the SW direction. LD₂ experienced a total dust mass loss of ∼10⁸ kg and dust mass loss rate of ∼6 kg/s with Afρ/cross-section varying between ∼85 cm/125 km² and ∼200 cm/310 km² between 2019 April 9 and 2019 Nov 8. If the Afρ/cross-section increase remained constant, it implies that LD₂ has remained active since ∼2018 November when it came within 4.8 au of the Sun, a typical distance for comets to begin sublimation of H₂O. From our 4.5 μm Spitzer observations, we set a limit on CO/CO₂ gas production of ∼10²⁷/∼10²⁶ mol/s. Multiple bandpass photometry of LD₂ taken by the GROWTH network measured in a 10,000 km aperture provide color measurements of g-r = 0.59±0.03, r-i = 0.18±0.05, and i-z = 0.01±0.07, colors typical of comets. We set a spectroscopic upper limit to the production of H₂O gas of ∼80 kg/s. Improving the orbital solution for LD₂ with our observations, we determine that the long-term orbit of LD₂ is that of a typical Jupiter Family Comet having close encounters with Jupiter coming within ∼0.5 Hill radius in the last ∼3 y to within 0.8 Hill radius in ∼9 y and has a 95% chance of being ejected from the Solar System in < 10 Myr

Kilonova Luminosity Function Constraints Based on Zwicky Transient Facility Searches for 13 Neutron Star Merger Triggers during O3

We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and neutron star black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) and undertook follow-up with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW triggers had a median localization area of 4480 deg², a median distance of 267 Mpc, and false-alarm rates ranging from 1.5 to 10⁻²⁵ yr⁻¹. The ZTF coverage in the g and r bands had a median enclosed probability of 39%, median depth of 20.8 mag, and median time lag between merger and the start of observations of 1.5 hr. The O3 follow-up by the GROWTH team comprised 340 UltraViolet/Optical/InfraRed (UVOIR) photometric points, 64 OIR spectra, and three radio images using 17 different telescopes. We find no promising kilonovae (radioactivity-powered counterparts), and we show how to convert the upper limits to constrain the underlying kilonova luminosity function. Initially, we assume that all GW triggers are bona fide astrophysical events regardless of false-alarm rate and that kilonovae accompanying BNS and NSBH mergers are drawn from a common population; later, we relax these assumptions. Assuming that all kilonovae are at least as luminous as the discovery magnitude of GW170817 (−16.1 mag), we calculate that our joint probability of detecting zero kilonovae is only 4.2%. If we assume that all kilonovae are brighter than −16.6 mag (the extrapolated peak magnitude of GW170817) and fade at a rate of 1 mag day⁻¹ (similar to GW170817), the joint probability of zero detections is 7%. If we separate the NSBH and BNS populations based on the online classifications, the joint probability of zero detections, assuming all kilonovae are brighter than −16.6 mag, is 9.7% for NSBH and 7.9% for BNS mergers. Moreover, no more than 10⁻⁴, or φ > 30° to be consistent with our limits. We look forward to searches in the fourth GW observing run; even 17 neutron star mergers with only 50% coverage to a depth of −16 mag would constrain the maximum fraction of bright kilonovae to <25%