A Deep-Unfolded Spatiotemporal RPCA Network For L+S Decomposition

Low-rank and sparse decomposition based methods find their use in many applications involving background modeling such as clutter suppression and object tracking. While Robust Principal Component Analysis (RPCA) has achieved great success in performing this task, it can take hundreds of iterations to converge and its performance decreases in the presence of different phenomena such as occlusion, jitter and fast motion. The recently proposed deep unfolded networks, on the other hand, have demonstrated better accuracy and improved convergence over both their iterative equivalents as well as over other neural network architectures. In this work, we propose a novel deep unfolded spatiotemporal RPCA (DUST-RPCA) network, which explicitly takes advantage of the spatial and temporal continuity in the low-rank component. Our experimental results on the moving MNIST dataset indicate that DUST-RPCA gives better accuracy when compared with the existing state of the art deep unfolded RPCA networks

Are ESG Stocks Safe-Haven during COVID-19?

This study contributes to the debate on safe-haven characteristics of environmental, social, and governance (ESG) stocks during COVID-19 pandemic. Using wavelet coherence framework on four major ESG stock indices from global and emerging stock markets, and two proxies of COVID-19 fear over the period from February 5th, 2020, to March 18th, 2021, we find a strong and positive co-movement between health fear index of COVID-19 and returns on ESG stocks suggesting the existence of safe-haven properties in ESG stocks. However, we also observe a negative co-movement between stock market base proxy of COVID-19 and returns on ESG indices, suggesting that safe-haven properties of ESG stocks are contingent upon the proxy of COVID-19 pandemic. Our findings are of particular interest for the investors and asset managers who may use ESG stocks to diversify their portfolios during health crisis due to COVID-19 pandemic

Large Rashba splittings in bulk and monolayer of BiAs

Two-dimensional materials with Rashba split bands near the Fermi level are key to developing upcoming next-generation spintronics. They enable generating, detecting, and manipulating spin currents without an external magnetic field. Here, we propose BiAs as a novel layered semiconductor with large Rashba splitting in bulk and monolayer forms. Using first-principles calculations, we determined the lowest energy structure of BiAs and its basic electronic properties. Bulk BiAs has a layered crystal structure with two atoms in a rhombohedral primitive cell, similar to the parent Bi and As elemental phases. It is a semiconductor with a narrow and indirect band gap. The spin-orbit coupling leads to Rashba-Dresselhaus spin splitting and characteristic spin texture around the L-point in the Brillouin zone of the hexagonal conventional unit cell, with Rashba energy and Rashba coupling constant for valence (conduction) band of $E_R$= 137 meV (93 meV) and $\alpha_R$= 6.05 eV\AA~(4.6 eV{\AA}). In monolayer form (i.e., composed of a BiAs bilayer), BiAs has a much larger and direct band gap at $\Gamma$, with a circular spin texture characteristic of a pure Rashba effect. The Rashba energy $E_R$= 18 meV and Rashba coupling constant $\alpha_R$= 1.67 eV{\AA} of monolayer BiAs are quite large compared to other known 2D materials, and these values are shown to increase under tensile biaxial strain.Comment: 15pages,9figure

The deep-acceptor nature of the chalcogen vacancies in 2D transition-metal dichalcogenides

Chalcogen vacancies in the semiconducting monolayer transition-metal dichalcogenides (TMDs) have frequently been invoked to explain a wide range of phenomena, including both unintentional p-type and n-type conductivity, as well as sub-band gap defect levels measured via tunneling or optical spectroscopy. These conflicting interpretations of the deep versus shallow nature of the chalcogen vacancies are due in part to shortcomings in prior first-principles calculations of defects in the semiconducting two-dimensional (2D) TMDs that have been used to explain experimental observations. Here we report results of hybrid density functional calculations for the chalcogen vacancy in a series of monolayer TMDs, correctly referencing the thermodynamic charge transition levels to the fundamental band gap (as opposed to the optical band gap). We find that the chalcogen vacancies are deep acceptors and cannot lead to n-type or p-type conductivity. Both the (0/$-1$) and ($-$1/$-$2) transition levels occur in the gap, leading to paramagnetic charge states S=1/2 and S=1, respectively, in a collinear-spin representation. We discuss trends in terms of the band alignments between the TMDs, which can serve as a guide to future experimental studies of vacancy behavior

A compression of Kaplan Meier vs. Weighted Kaplan-Meier in Comparing Estimation of Heavy Censoring Data

This study aimed to compare estimations of Kaplan-Meier (K-M) and Weighted Kaplan-Meier (W-K-M) as an alternative method to deal with the problem of heavy-censoring data for Children under-five years, whom do not reach the event of interest during the end period of the study. Usually, this kind of biostatistics study has been estimated based on K-M. In such situations survival probabilities, can be estimated for censored observation by K-M estimator. However, in case of heavy censoring these estimates are biased and overestimate the survival probabilities. For heavy censoring a new method was proposed (Bahrawar Jan, 2005) to estimate the survival probabilities by weighting the censored observations by non-censoring rate. But the main defect in this weighted method is that it gives zero weight to the last censored observation. The survival rates of the patients with standard error estimation based on K-M vs. W-K-M for 5 years shown in Table 3. In cases where censoring assumption is not made, and the study has many censored observations, estimations obtained from the K-M are biased and are estimated higher than its real amount. But W-K-M decreases bias of survival probabilities by providing appropriate weights and presents more accurate understanding. Weighted Kaplan-Meier was the suitable method to estimate the Survival Time of these patients, have determined after surgery at Jafar ibn Oaf Hospital for Children in Sudan form January 2012 to December 2016. The five years’ survival rate for these patients were evaluated based on K-M and W-K-M. A total of 245(22%) Children<5 years passed away by the end of the study and 853(78%) Children<5 years were censored. The median of survival time for these patients was 16 days

Weak antilocalization in quasi-two-dimensional electronic states of epitaxial LuSb thin films

Observation of large non-saturating magnetoresistance in rare-earth monopnictides has raised enormous interest in understanding the role of its electronic structure. Here, by a combination of molecular-beam epitaxy, low-temperature transport, angle-resolved photoemssion spectroscopy, and hybrid density functional theory we have unveiled the bandstructure of LuSb, where electron-hole compensation is identified as a mechanism responsible for large magnetoresistance in this topologically trivial compound. In contrast to bulk single crystal analogues, quasi-two-dimensional behavior is observed in our thin films for both electron and holelike carriers, indicative of dimensional confinement of the electronic states. Introduction of defects through growth parameter tuning results in the appearance of quantum interference effects at low temperatures, which has allowed us to identify the dominant inelastic scattering processes and elucidate the role of spin-orbit coupling. Our findings open up new possibilities of band structure engineering and control of transport properties in rare-earth monopnictides via epitaxial synthesis.Comment: 20 pages, 12 figures; includes supplementary informatio

Outbreak of dengue fever in Karachi 2006: a clinical perspective

OBJECTIVE: This study reports clinical manifestations and spectrum of severity of dengue fever (DF), dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) in adult patients admitted during 2006 outbreak in Karachi. A rough estimation of cost of care was also calculated. METHODS: A cross-sectional study was done at a tertiary care hospital in Karachi from January to December 2006. Patients suspected of having DF with positive dengue IgM antibodies were included and records were reviewed. Patients were divided into DF, DHF and DSS as per WHO classification, and the severity of clinical manifestations was determined. RESULTS: A total of 278 (65.72%) of 423 patients admitted with suspected dengue illness had positive IgM titer. Mean age was 31 +/- 12.9 years, with 168 (60%) males and 110 (40%) females. Common presenting symptoms were fever (100%), vomiting (78%), epigastric pain (52%), bleeding tendencies (34%), and erythematous rash (33%). Thrombocytopenia (60%), Leucopenia (45%), elevated transaminases (ALT 71%; AST 88%), and deranged PT (22%) and aPTT (75%) were the predominant. Laboratory parameters: DF was diagnosed in 169 (61%) patients, 82 (29%) were classified as DHF, and 27 (10%) as DSS. Patients with DHF/DSS were younger (n=60, 55%) and had longer hospital stay (p=0.001). Case fatality rate for DHF/DSS group was 4.6%. CONCLUSION: It was estimated that endemicity of DF is on the rise in Karachi and a significant proportion of patients had DHF and DSS. Younger patients develop DHF and DSS and have high case fatality rate

CT analysis of subcutaneous and visceral adipose tissue in normal BMI subjects: association with level of physical activity and hypertension

Background: The distribution of adipose tissue, complex factors affecting it and its pathological consequences are among the hot topics in medical research nowadays. Most of the studies reported in the literature however describe the association of factors affecting the fat distribution in overweight and obese individuals. This particular study was however planned to find out the same in subjects having normal basal metabolic index (BMI). The objectives of the study were to analyze total adipose tissue (TAT), subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in the abdomen volumetrically using CT, to establish the association of these to the levels of physical activity, presence or absence of hypertension and to compare these associations in both the genders.Methods: A prospective study was carried out on seventy five, normal BMI subjects aged between 20–50 years. CT imaging was used for volumetric measurement of TAT, SAT and VAT. Pearson’s correlation of these were then found out with age. Kruskal Wallis test was also performed to compare these in hypertensive and non-hypertensive subjects and in those with different physical activity levels (PAL).Results: Women showed significantly higher volumes of TAT and SAT. Men showed statistically significant correlations of TAT and VAT with age. SAT volumes had significant negative association with the PAL in both genders. Men showed higher responsiveness of fat deposition in all compartments to the presence of hypertension.Conclusion: In conclusion, factors such as gender, age, level of physical activity and hypertension affect the site specific deposition of fat even in those individuals who aren’t over-weight or obese.Keywords: Total Adipose Tissue (TAT); Subcutaneous Adipose Tissue (SAT); Visceral Adipose Tissue (VAT