National Research University – Higher School of Economics

About: National Research University – Higher School of Economics is a education organization based out in Moscow, Russia. It is known for research contribution in the topics: Population & Computer science. The organization has 12873 authors who have published 23376 publications receiving 256396 citations.

Ultrafast Sample placement on Existing tRees (UShER) enables real-time phylogenetics for the SARS-CoV-2 pandemic.

Abstract: As the SARS-CoV-2 virus spreads through human populations, the unprecedented accumulation of viral genome sequences is ushering in a new era of 'genomic contact tracing'-that is, using viral genomes to trace local transmission dynamics. However, because the viral phylogeny is already so large-and will undoubtedly grow many fold-placing new sequences onto the tree has emerged as a barrier to real-time genomic contact tracing. Here, we resolve this challenge by building an efficient tree-based data structure encoding the inferred evolutionary history of the virus. We demonstrate that our approach greatly improves the speed of phylogenetic placement of new samples and data visualization, making it possible to complete the placements under the constraints of real-time contact tracing. Thus, our method addresses an important need for maintaining a fully updated reference phylogeny. We make these tools available to the research community through the University of California Santa Cruz SARS-CoV-2 Genome Browser to enable rapid cross-referencing of information in new virus sequences with an ever-expanding array of molecular and structural biology data. The methods described here will empower research and genomic contact tracing for SARS-CoV-2 specifically for laboratories worldwide.

Subnational Appointments in Authoritarian Regimes: Evidence from Russian Gubernatorial Appointments

Abstract: Elections are among the most important and least understood institutions in contemporary authoritarian regimes. Theoretically, electoral authoritarian regimes should have an informational advantage that makes them more robust than other types of authoritarian regimes, but much empirical evidence suggests otherwise. In this article we offer a new perspective on why this might be the case. Specifically, we consider how authoritarian elections influence a ruler’s choices in making cadre appointments. We argue that the imperative of winning authoritarian elections forces authoritarian leaders to prioritize the appointment of politically loyal cadres, who can help the regime win elections. This choice often comes at the expense of appointing officials who are competent at making good public policy and promoting economic development, factors that may contribute to long-term regime stability. We test this theory using an original dataset of gubernatorial appointments in one leading contemporary authoritarian reg...

Sex Workers and the Cost of Safe Sex: The Compensating Differential for Condom Use Among Calcutta Prostitutes

Abstract: Prostitution is often called the world's oldest profession, yet economists almost never study it. The practice of safe sex by commercial sex workers is considered central to preventing the transmission of AIDS in developing countries - yet sex workers in Calcutta who regularly use condoms suffer a 79 percent loss in their average earnings per sex act. The practice of safe sex by commercial sex workers is considered central to preventing the transmission of AIDS in developing countries. Rao, Gupta, and Jana estimate the compensating differential for condom use among sex workers in Calcutta, based on results from a survey conducted in 1993. If, as suggested by anecdotal evidence, this loss in income is large, it would indicate the existence of strong disincentives for practicing safe sex. To identify the relationship between condom use and the average price per sex act, they follow an instrumental variable approach, exploiting an intervention program focused on providing information about the AIDS virus and about safe sex practices. The program, instituted in 1992, was not systematically administered. Using this method, they found that sex workers who always use condoms face a loss of 79 percent in the average earnings per sex act. This paper - a product of Poverty and Human Resources, Development Research Group - is part of a larger effort in the group to understand the behavior underlying HIV/AIDS transmission. Vijayendra Rao may be contacted at vrao@worldbank.org.

Implicit Reparameterization Gradients

Abstract: By providing a simple and efficient way of computing low-variance gradients of continuous random variables, the reparameterization trick has become the technique of choice for training a variety of latent variable models. However, it is not applicable to a number of important continuous distributions. We introduce an alternative approach to computing reparameterization gradients based on implicit differentiation and demonstrate its broader applicability by applying it to Gamma, Beta, Dirichlet, and von Mises distributions, which cannot be used with the classic reparameterization trick. Our experiments show that the proposed approach is faster and more accurate than the existing gradient estimators for these distributions.