Stock Market Volatility, Speculative Short Sellers and Weekend Effect: International Evidence

We test the Chen and Singal (2003) hypothesis that speculative short sellers add to the selling pressure on Mondays, and hence add to the weekend effect, by examining evidence from 60 market indices. We find strong evidence that, until about a decade ago, the actions of short sellers could explain the weekend ef- fect. Recently, however, the relationship between short sales and the weekend effect is gradually dissi- pating in developed markets, probably due to the cross-market hedges of short sellers. These findings strongly support, rather than weaken, the Chen and Singal hypothesis

Stock Market Volatility, Speculative Short Sellers and Weekend Effect: International Evidence

We test the Chen and Singal (2003) hypothesis that speculative short sellers add to the selling pressure on Mondays, and hence add to the weekend effect, by examining evidence from 60 market indices. We find strong evidence that, until about a decade ago, the actions of short sellers could explain the weekend ef- fect. Recently, however, the relationship between short sales and the weekend effect is gradually dissi- pating in developed markets, probably due to the cross-market hedges of short sellers. These findings strongly support, rather than weaken, the Chen and Singal hypothesis

Naked singularities in Tolman-Bondi-de Sitter collapse

We study the formation of central naked singularities in spherical dust collapse with a cosmological constant. We find that the central curvature singularity is locally naked, Tipler strong, and generic, in the sense that it forms from a non-zero-measure set of regular initial data. We also find that the Weyl and Ricci curvature scalars diverge at the singularity, with the former dominating over the latter, thereby signaling the non-local origin of the singularity.Comment: 8 pages, RevTeX, 1 eps figure; accepted for publication in Phys. Rev.

Identification of disease-linked hyperactivating mutations in UBE3A through large-scale functional variant analysis

The mechanisms that underlie the extensive phenotypic diversity in genetic disorders are poorly understood. Here, we develop a large-scale assay to characterize the functional valence (gain or loss-of-function) of missense variants identified in UBE3A, the gene whose loss-of-function causes the neurodevelopmental disorder Angelman syndrome. We identify numerous gain-of-function variants including a hyperactivating Q588E mutation that strikingly increases UBE3A activity above wild-type UBE3A levels. Mice carrying the Q588E mutation exhibit aberrant early-life motor and communication deficits, and individuals possessing hyperactivating UBE3A variants exhibit affected phenotypes that are distinguishable from Angelman syndrome. Additional structure-function analysis reveals that Q588 forms a regulatory site in UBE3A that is conserved among HECT domain ubiquitin ligases and perturbed in various neurodevelopmental disorders. Together, our study indicates that excessive UBE3A activity increases the risk for neurodevelopmental pathology and suggests that functional variant analysis can help delineate mechanistic subtypes in monogenic disorders

Identification of disease-linked hyperactivating mutations in UBE3A through large-scale functional variant analysis

The mechanisms that underlie the extensive phenotypic diversity in genetic disorders are poorly understood. Here, we develop a large-scale assay to characterize the functional valence (gain or loss-of-function) of missense variants identified in UBE3A, the gene whose loss-of-function causes the neurodevelopmental disorder Angelman syndrome. We identify numerous gain-of-function variants including a hyperactivating Q588E mutation that strikingly increases UBE3A activity above wild-type UBE3A levels. Mice carrying the Q588E mutation exhibit aberrant early-life motor and communication deficits, and individuals possessing hyperactivating UBE3A variants exhibit affected phenotypes that are distinguishable from Angelman syndrome. Additional structure-function analysis reveals that Q588 forms a regulatory site in UBE3A that is conserved among HECT domain ubiquitin ligases and perturbed in various neurodevelopmental disorders. Together, our study indicates that excessive UBE3A activity increases the risk for neurodevelopmental pathology and suggests that functional variant analysis can help delineate mechanistic subtypes in monogenic disorders

Peregrine: A Pattern-Aware Graph Mining System

Graph mining workloads aim to extract structural properties of a graph by exploring its subgraph structures. General purpose graph mining systems provide a generic runtime to explore subgraph structures of interest with the help of user-defined functions that guide the overall exploration process. However, the state-of-the-art graph mining systems remain largely oblivious to the shape (or pattern) of the subgraphs that they mine. This causes them to: (a) explore unnecessary subgraphs; (b) perform expensive computations on the explored subgraphs; and, (c) hold intermediate partial subgraphs in memory; all of which affect their overall performance. Furthermore, their programming models are often tied to their underlying exploration strategies, which makes it difficult for domain users to express complex mining tasks. In this paper, we develop Peregrine, a pattern-aware graph mining system that directly explores the subgraphs of interest while avoiding exploration of unnecessary subgraphs, and simultaneously bypassing expensive computations throughout the mining process. We design a pattern-based programming model that treats "graph patterns" as first class constructs and enables Peregrine to extract the semantics of patterns, which it uses to guide its exploration. Our evaluation shows that Peregrine outperforms state-of-the-art distributed and single machine graph mining systems, and scales to complex mining tasks on larger graphs, while retaining simplicity and expressivity with its "pattern-first" programming approach.Comment: This is the full version of the paper appearing in the European Conference on Computer Systems (EuroSys), 202

Metabolic health and adiposity transitions and risks of type 2 diabetes and cardiovascular diseases: a systematic review and meta-analysis

Abstract Background Metabolic health status and levels of adiposity are prone to change over time. Mixed results have been reported regarding the extent by which changes in metabolic health and weight affect cardiometabolic risks. This systematic review and meta-analysis aims to examine the association between transitions in metabolic health and adiposity status on risk of incident type 2 diabetes (T2DM) and cardiovascular disease (CVD) events. Methods A systematic literature search was conducted on MEDLINE and EMBASE through August 2022 for prospective cohort studies examining transitions in metabolic health and adiposity status and risk of incident T2DM and CVDs without restrictions on language or publication status. Meta-analysis was performed to summarize hazard ratios for T2DM and composite CVD events separately using random-effects model. Results A total of 17 studies were included. Compared to stable metabolically healthy status, transition to metabolically unhealthy status significantly increased the risk of incident T2DM and composite CVD events among individuals with normal weight and individuals with overweight/obesity. Compared to stable metabolically unhealthy status, transition to metabolically healthy status significantly lowered the risk among individuals with normal weight and individuals with overweight/obesity. When metabolic health status remained unchanged, progression from normal weight to overweight/obesity significantly increased risk of CVDs but not risk of T2DM. Conclusion The impact of change in metabolic health on the risks of T2DM and CVD is more prominent than that of change to body mass index category. Obesity treatment should consider prioritizing improvement in metabolic health parameters over focusing on the extent of weight loss only

Metal organic framework-based nanostructure materials: applications for non-lithium ion battery electrodes

Non-lithium ion (e.g., Al3+, Ca2+, K+, Mg2+, Na+, and Zn2+) batteries have emerged as a promising platform for next-generation energy storage systems. Due to their high natural abundance, high theoretical capacities, and reliable and safe operation, non-lithium ion batteries have been considered as potential substitutes for lithium-ion batteries (LIBs) in recent years. However, progress in the development of non-LIBs has been obstructed by unique challenges for these systems, such as the relatively large ionic radius for the metals (e.g., Ca, K, Na), sluggish electrochemical kinetics, and limitations regarding the selection of compatible electrolytes. In this regard, researchers have targeted metal-organic frameworks (MOFs), which are crystalline porous frameworks with large specific surface areas and excellent synthetic tunability, chemical diversity, and stability, as prime candidates for use as high-performance electrode materials in non-LIBs. Herein, we summarize the recent contributions and progress of pristine MOFs and MOF derivatives as electrode materials for non-LIB applications, focusing on the aspects of rational design and sophisticated morphological control in the construction of MOF-based electrodes, in addition to evaluating the electrochemical performance of the resulting batteries. Finally, we highlight the opportunities and challenges for MOF-based electrodes for non-LIBs, and more broadly, offer our perspectives on the future development of non-LIBs.N