148 research outputs found

    The central limit problem for random vectors with symmetries

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    Motivated by the central limit problem for convex bodies, we study normal approximation of linear functionals of high-dimensional random vectors with various types of symmetries. In particular, we obtain results for distributions which are coordinatewise symmetric, uniform in a regular simplex, or spherically symmetric. Our proofs are based on Stein's method of exchangeable pairs; as far as we know, this approach has not previously been used in convex geometry and we give a brief introduction to the classical method. The spherically symmetric case is treated by a variation of Stein's method which is adapted for continuous symmetries.Comment: AMS-LaTeX, uses xy-pic, 23 pages; v3: added new corollary to Theorem

    A transcriptomic analysis of Echinococcus granulosus larval stages:implications for parasite biology and host adaptation

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    The cestode Echinococcus granulosus--the agent of cystic echinococcosis, a zoonosis affecting humans and domestic animals worldwide--is an excellent model for the study of host-parasite cross-talk that interfaces with two mammalian hosts. To develop the molecular analysis of these interactions, we carried out an EST survey of E. granulosus larval stages. We report the salient features of this study with a focus on genes reflecting physiological adaptations of different parasite stages.We generated ~10,000 ESTs from two sets of full-length enriched libraries (derived from oligo-capped and trans-spliced cDNAs) prepared with three parasite materials: hydatid cyst wall, larval worms (protoscoleces), and pepsin/H(+)-activated protoscoleces. The ESTs were clustered into 2700 distinct gene products. In the context of the biology of E. granulosus, our analyses reveal: (i) a diverse group of abundant long non-protein coding transcripts showing homology to a middle repetitive element (EgBRep) that could either be active molecular species or represent precursors of small RNAs (like piRNAs); (ii) an up-regulation of fermentative pathways in the tissue of the cyst wall; (iii) highly expressed thiol- and selenol-dependent antioxidant enzyme targets of thioredoxin glutathione reductase, the functional hub of redox metabolism in parasitic flatworms; (iv) candidate apomucins for the external layer of the tissue-dwelling hydatid cyst, a mucin-rich structure that is critical for survival in the intermediate host; (v) a set of tetraspanins, a protein family that appears to have expanded in the cestode lineage; and (vi) a set of platyhelminth-specific gene products that may offer targets for novel pan-platyhelminth drug development.This survey has greatly increased the quality and the quantity of the molecular information on E. granulosus and constitutes a valuable resource for gene prediction on the parasite genome and for further genomic and proteomic analyses focused on cestodes and platyhelminths

    The effects of centralising electoral management board design

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    The public administration of elections frequently fails. Variation in the performance of electoral management boards around the world has been demonstrated, illustrated by delays in the count, inaccurate or incomplete voter registers, or severe queues at polling stations. Centralising the management of the electoral process has often been proposed as a solution. There has been little theorisation and no empirical investigations into the effects that centralising an already decentralised system would have, however. This article addresses this lacuna by conceptualising centralisation through the literature on bureaucratic control and discretion. It then empirically investigates the effects through a case study of centralisation in two UK referendums. Semi-structured interviews were used with those who devised the policy instrument and those who were subject to it. The introduction of central directions had some of the desired effects such as producing more consistent services and eliminating errors. It also had side effects, however, such as reducing economic efficiency in some areas and overlooking local knowledge. Furthermore, the reforms caused a decline of staff morale, job satisfaction and souring of relations among stakeholder organisations. The process of making organisational change therefore warrants closer attention by policy makers and future scholarship on electoral integrity

    Eliciting taxpayer preferences increases tax compliance

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    Two experiments show that eliciting taxpayer preferences on government spendingβ€”providing taxpayer agency--increases tax compliance. We first create an income and taxation environment in a laboratory setting to test for compliance with a lab tax. Allowing a treatment group to express nonbinding preferences over tax spending priorities, leads to a 16% increase in tax compliance. A followup online study tests this treatment with a simulation of paying US federal taxes. Allowing taxpayers to signal their preferences on the distribution of government spending, results in a 15% reduction in the stated take-up rate of a questionable tax loophole. Providing taxpayer agency recouples tax payments with the public services obtained in return, reduces general anti-tax sentiment, and holds satisfaction with tax payment stable despite increased compliance with tax dues. With tax noncompliance costing the US government $385billion annually, providing taxpayer agency could have meaningful economic impact. At the same time, giving taxpayers a voice may act as a two-way "nudge," transforming tax payment from a passive experience to a channel of communication between taxpayers and government

    Genome Sequencing Shows that European Isolates of Francisella tularensis Subspecies tularensis Are Almost Identical to US Laboratory Strain Schu S4

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    BACKGROUND: Francisella tularensis causes tularaemia, a life-threatening zoonosis, and has potential as a biowarfare agent. F. tularensis subsp. tularensis, which causes the most severe form of tularaemia, is usually confined to North America. However, a handful of isolates from this subspecies was obtained in the 1980s from ticks and mites from Slovakia and Austria. Our aim was to uncover the origins of these enigmatic European isolates. METHODOLOGY/PRINCIPAL FINDINGS: We determined the complete genome sequence of FSC198, a European isolate of F. tularensis subsp. tularensis, by whole-genome shotgun sequencing and compared it to that of the North American laboratory strain Schu S4. Apparent differences between the two genomes were resolved by re-sequencing discrepant loci in both strains. We found that the genome of FSC198 is almost identical to that of Schu S4, with only eight SNPs and three VNTR differences between the two sequences. Sequencing of these loci in two other European isolates of F. tularensis subsp. tularensis confirmed that all three European isolates are also closely related to, but distinct from Schu S4. CONCLUSIONS/SIGNIFICANCE: The data presented here suggest that the Schu S4 laboratory strain is the most likely source of the European isolates of F. tularensis subsp. tularensis and indicate that anthropogenic activities, such as movement of strains or animal vectors, account for the presence of these isolates in Europe. Given the highly pathogenic nature of this subspecies, the possibility that it has become established wild in the heartland of Europe carries significant public health implications

    CHOP Mediates Endoplasmic Reticulum Stress-Induced Apoptosis in Gimap5-Deficient T Cells

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    Gimap5 (GTPase of the immunity-associated protein 5) has been linked to the regulation of T cell survival, and polymorphisms in the human GIMAP5 gene associate with autoimmune disorders. The BioBreeding diabetes-prone (BBDP) rat has a mutation in the Gimap5 gene that leads to spontaneous apoptosis of peripheral T cells by an unknown mechanism. Because Gimap5 localizes to the endoplasmic reticulum (ER), we hypothesized that absence of functional Gimap5 protein initiates T cell death through disruptions in ER homeostasis. We observed increases in ER stress-associated chaperones in T cells but not thymocytes or B cells from Gimap5βˆ’/βˆ’ BBDP rats. We then discovered that ER stress-induced apoptotic signaling through C/EBP-homologous protein (CHOP) occurs in Gimap5βˆ’/βˆ’ T cells. Knockdown of CHOP by siRNA protected Gimap5βˆ’/βˆ’ T cells from ER stress-induced apoptosis, thereby identifying a role for this cellular pathway in the T cell lymphopenia of the BBDP rat. These findings indicate a direct relationship between Gimap5 and the maintenance of ER homeostasis in the survival of T cells

    Genetic Identification of a Network of Factors that Functionally Interact with the Nucleosome Remodeling ATPase ISWI

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    Nucleosome remodeling and covalent modifications of histones play fundamental roles in chromatin structure and function. However, much remains to be learned about how the action of ATP-dependent chromatin remodeling factors and histone-modifying enzymes is coordinated to modulate chromatin organization and transcription. The evolutionarily conserved ATP-dependent chromatin-remodeling factor ISWI plays essential roles in chromosome organization, DNA replication, and transcription regulation. To gain insight into regulation and mechanism of action of ISWI, we conducted an unbiased genetic screen to identify factors with which it interacts in vivo. We found that ISWI interacts with a network of factors that escaped detection in previous biochemical analyses, including the Sin3A gene. The Sin3A protein and the histone deacetylase Rpd3 are part of a conserved histone deacetylase complex involved in transcriptional repression. ISWI and the Sin3A/Rpd3 complex co-localize at specific chromosome domains. Loss of ISWI activity causes a reduction in the binding of the Sin3A/Rpd3 complex to chromatin. Biochemical analysis showed that the ISWI physically interacts with the histone deacetylase activity of the Sin3A/Rpd3 complex. Consistent with these findings, the acetylation of histone H4 is altered when ISWI activity is perturbed in vivo. These findings suggest that ISWI associates with the Sin3A/Rpd3 complex to support its function in vivo
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