Project description:We explore the asymptotic properties of strategic models of network formation in very large populations. Specifically, we focus on (undirected) exponential random graph models. We want to recover a set of parameters from the individuals' utility functions using the observation of a single, but large, social network. We show that, under some conditions, a simple logit-based estimator is coherent, consistent and asymptotically normally distributed under a weak version of homophily. The approach is compelling as the computing time is minimal and the estimator can be easily implemented using pre-programmed estimators available in most statistical packages. We provide an application of our method using the Add Health database.
Project description:The relationships between polypeptide composition, sequence, structure and function have been puzzling biologists ever since first protein sequences were determined. Here, we study the statistics of occurrence of all possible pentapeptide sequences in known proteins. To compensate for the non-uniform distribution of individual amino acid residues in protein sequences, we investigate separately all possible permutations of every given amino acid composition. For the majority of permutation groups we find that pentapeptide occurrences deviate strongly from the expected binomial distributions, and that the observed distributions are also characterized by high numbers of outlier sequences. An analysis of identified outliers shows they often contain known motifs and rare amino acids, suggesting that they represent important functional elements. We further compare the pentapeptide composition of regions known to correspond to protein domains with that of non-domain regions. We find that a substantial number of pentapeptides is clearly strongly favored in protein domains. Finally, we show that over-represented pentapeptides are significantly related to known functional motifs and to predicted ancient structural peptides.
Project description:This paper explores the nature of parental involvement in youth basketball in Israel with regard to parenting style and in the context of dilemmas and ethical issues. It is well established that parental involvement in their child's sporting activity has vast implications on the child's motivation and enjoyment. With reference to Israeli society, only a few studies have focused on this subject. In order to address this lacuna, we used two questionnaires, given to 173 youth basketball players (child questionnaire) and their parents (parent questionnaire). Key findings illustrate three main themes. First, a higher level of satisfaction and contentment among basketball players whose parents demonstrated greater involvement; second, that parental emotional involvement is the most important variable for young athletes' satisfaction; and finally, differences in gender roles reveal that fathers are more involved with logistics, while mothers are more dominant in emotional involvement. Moreover, the findings demonstrate that parents should mainly place emphasis on emotional involvement. However, we suggest that parents do not bypass logistical care as this may create opportunities for greater emotional support and therefore greater child satisfaction.
Project description:IntroductionThe aim of this study was to describe peri-procedural antithrombotic use in patients undergoing transcatheter aortic valve replacement (TAVR) at a single academic medical center.MethodsRetrospective collection of antiplatelet and anticoagulant use during the index hospitalization for all patients undergoing TAVR at our institution from April 2009 through March 2014.ResultsOf a total of 255 patients undergoing the procedure, 132 (51%) had an indication for anticoagulation pre-TAVR and 92 (70% of those with an indication) were on treatment. On discharge, 106 patients (44% of total surviving to discharge, 73% of those surviving with an indication for anticoagulation) were treated with oral anticoagulation. Of these patients, 89 (84%) were discharged on aspirin and an oral anticoagulant without clopidogrel. Only 122 (51% of total patients) were discharged on the regimen of aspirin and clopidogrel alone.ConclusionPeri-procedural antithrombotic regimens vary greatly following TAVR. More than half of patients have an indication for anticoagulation following the procedure. Most patients at our institution who require anticoagulation are discharged on aspirin and an oral anticoagulant, though the optimal regimen requires further investigation.
Project description:Voters evaluate political candidates not only based on their recent record but their history, often faced with weighing the relevance of long-past misdeeds in current appraisal. How should a distant transgression be taken to reflect on the present? Across multiple years, political figures and incidents, we found that people’s subjective perceptions of time concerning political candidate’s histories can differ radically, regardless of objective fact; political bias shapes people’s perception of the time of things past. Results showed that despite equidistant calendar time, people subjectively view a favored politician’s successes and opposing politician’s failures as much closer in time, while a favored politician’s failures and opponent’s success seem much further away. Studies 1–3 tested the proposed phenomena across distinct (real and hypothetical) political contexts, while Study 4 tested the causal effects of temporal distance framing. Study 5 provided a final preregistered test of the findings. Overall, we demonstrate that partisans can protect their candidates and attack opponents by shifting their perception of time.
Project description:MotivationFunctional genomics research has expanded enormously in the last decade thanks to the cost reduction in high-throughput technologies and the development of computational tools that generate, standardize and share information on gene and protein function such as the Gene Ontology (GO). Nevertheless, many biologists, especially working with non-model organisms, still suffer from non-existing or low-coverage functional annotation, or simply struggle retrieving, summarizing and querying these data.ResultsThe Blast2GO Functional Annotation Repository (B2G-FAR) is a bioinformatics resource envisaged to provide functional information for otherwise uncharacterized sequence data and offers data mining tools to analyze a larger repertoire of species than currently available. This new annotation resource has been created by applying the Blast2GO functional annotation engine in a strongly high-throughput manner to the entire space of public available sequences. The resulting repository contains GO term predictions for over 13.2 million non-redundant protein sequences based on BLAST search alignments from the SIMAP database. We generated GO annotation for approximately 150 000 different taxa making available 2000 species with the highest coverage through B2G-FAR. A second section within B2G-FAR holds functional annotations for 17 non-model organism Affymetrix GeneChips.ConclusionsB2G-FAR provides easy access to exhaustive functional annotation for 2000 species offering a good balance between quality and quantity, thereby supporting functional genomics research especially in the case of non-model organisms.AvailabilityThe annotation resource is available at http://www.b2gfar.org.
Project description:Crystallization is in many cases a critical step for solving the three-dimensional structure of a protein molecule. Determining which set of chemicals to use in the initial screen is typically agnostic of the protein under investigation; however, crystallization efficiency could potentially be improved if this were not the case. Previous work has assumed that sequence similarity may provide useful information about appropriate crystallization cocktails; however, the authors are not aware of any quantitative verification of this assumption. This research investigates whether, given current information, one can detect any correlation between sequence similarity and crystallization cocktails. BLAST was used to quantitate the similarity between protein sequences in the Protein Data Bank, and this was compared with three estimations of the chemical similarities of the respective crystallization cocktails. No correlation was detected between proteins of similar (but not identical) sequence and their crystallization cocktails, suggesting that methods of determining screens based on this assumption are unlikely to result in screens that are better than those currently in use.
Project description:Stereo or '3D' vision is an important but costly process seen in several evolutionarily distinct lineages including primates, birds and insects. Many selective advantages could have led to the evolution of stereo vision, including range finding, camouflage breaking and estimation of object size. In this paper, we investigate the possibility that stereo vision enables praying mantises to estimate the size of prey by using a combination of disparity cues and angular size cues. We used a recently developed insect 3D cinema paradigm to present mantises with virtual prey having differing disparity and angular size cues. We predicted that if they were able to use these cues to gauge the absolute size of objects, we should see evidence for size constancy where they would strike preferentially at prey of a particular physical size, across a range of simulated distances. We found that mantises struck most often when disparity cues implied a prey distance of 2.5 cm; increasing the implied distance caused a significant reduction in the number of strikes. We, however, found no evidence for size constancy. There was a significant interaction effect of the simulated distance and angular size on the number of strikes made by the mantis but this was not in the direction predicted by size constancy. This indicates that mantises do not use their stereo vision to estimate object size. We conclude that other selective advantages, not size constancy, have driven the evolution of stereo vision in the praying mantis.This article is part of the themed issue 'Vision in our three-dimensional world'.