Hierarchical Coding for Distributed Computing

Coding for distributed computing supports low-latency computation by relieving the burden of straggling workers. While most existing works assume a simple master-worker model, we consider a hierarchical computational structure consisting of groups of workers, motivated by the need to reflect the architectures of real-world distributed computing systems. In this work, we propose a hierarchical coding scheme for this model, as well as analyze its decoding cost and expected computation time. Specifically, we first provide upper and lower bounds on the expected computing time of the proposed scheme. We also show that our scheme enables efficient parallel decoding, thus reducing decoding costs by orders of magnitude over non-hierarchical schemes. When considering both decoding cost and computing time, the proposed hierarchical coding is shown to outperform existing schemes in many practical scenarios.Comment: 7 pages, part of the paper is submitted to ISIT201

Assessing the joint effect of population stratification and sample selection in studies of gene-gene (environment) interactions

<p>Abstract</p> <p>Background</p> <p>It is well known that the presence of population stratification (PS) may cause the usual test in case-control studies to produce spurious gene-disease associations. However, the impact of the PS and sample selection (SS) is less known. In this paper, we provide a systematic study of the joint effect of PS and SS under a more general risk model containing genetic and environmental factors. We provide simulation results to show the magnitude of the bias and its impact on type I error rate of the usual chi-square test under a wide range of PS level and selection bias.</p> <p>Results</p> <p>The biases to the estimation of main and interaction effect are quantified and then their bounds derived. The estimated bounds can be used to compute conservative p-values for the association test. If the conservative p-value is smaller than the significance level, we can safely claim that the association test is significant regardless of the presence of PS or not, or if there is any selection bias. We also identify conditions for the null bias. The bias depends on the allele frequencies, exposure rates, gene-environment odds ratios and disease risks across subpopulations and the sampling of the cases and controls.</p> <p>Conclusion</p> <p>Our results show that the bias cannot be ignored even the case and control data were matched in ethnicity. A real example is given to illustrate application of the conservative p-value. These results are useful to the genetic association studies of main and interaction effects.</p

Fabrication of porous matrix membrane (PMM) using metal-organic framework as green template for water treatment

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Surface charge dynamics on ferroelectric PbZr0.48Ti0.52O3 films responding to the switching bias of electric force microscope

We investigated the role of surface charges in writing and reading ferroelectric bits on an epitaxial PbZr0.48Ti0.52O3 thin film by electric force microscopy (EFM). The sign of EFM surface potential was reversed within several hundred microseconds for 10 V. For a negative bias voltage of -10 V, EFM surface potential was reversed in several milliseconds. The different time scales of the EFM surface potential reversals originate from the screening of the ferroelectric polarization charges by the surface charges which pass over two different Schottky barriers depending on the applied bias polarity.X118sciescopu

Psychometric properties of measures designed to assess common mental health problems and wellbeing in adults with intellectual disabilities: a systematic review

Background: Multiple measures of mental health problems and mental wellbeing for adults with intellectual disabilities are available, but investigations into their reliability and validity are still in the early stages. The aim of this systematic review was to provide an update to previous evaluations of measures of common mental health problems and wellbeing in adults with mild to moderate intellectual disabilities (ID). Methods: A systematic search was performed across three databases (MEDLINE, PsycINFO and SCOPUS). The literature search was limited to the years from 2009 to 2021 and to the original English versions. Ten papers evaluating nine measures were reviewed, and the psychometric properties of these measures were discussed using the Characteristics of Assessment Instructions for Psychiatric Disorders in Persons with Intellectual Developmental Disorders as a framework. Results: Four measures had at least one rating of ‘good’ across both dimensions of reliability and at least one dimension of validity and were deemed to have promising psychometric properties: the Clinical Outcomes in Routine Evaluation-Learning Disabilities, Impact of Events Scale-Intellectual Disabilities, Lancaster and Northgate Trauma Scales and Self-Assessment and Intervention (self-report section). Additionally, these measures were developed through consultations with mental health professionals and/or people with IDs and thus were deemed to have good content validity. Conclusions: This review informs measurement choice for researchers and clinicians while highlighting a need for continued research efforts into the quality of measures available for people with IDs. The results were limited by incomplete psychometric evaluations of measures available. A paucity of psychometrically robust measures of mental wellbeing was observed

Self-esteem and its relationship with depression and anxiety in adults with intellectual disabilities: a systematic literature review

Background: In the general population, low self-esteem has been linked with poorer mental and physical health. This systematic literature review aimed to summarise and evaluate the findings of studies that examined self-esteem in adults with intellectual disabilities and links with mental health outcomes. / Method: A systematic search of PsycINFO, Web of Science and CINAHL was conducted to identify studies published between 1990 and 2021. The studies were appraised using the QualSyst tool. / Results: Twenty-six articles were identified of which two studies were removed from the review due to low quality. Studies reported mixed evidence regarding levels of self-esteem compared with the general population. Engagement in activities appeared to be linked with positive self-esteem, and perception of negative interpersonal life events as having a negative impact was associated with lower self-esteem. There was evidence of co-occurrence of low self-esteem and depression, but no studies examined the relationship between self-esteem and anxiety. / Conclusion: Reviewed studies provided mixed evidence on levels of self-esteem in this population, suggesting that factors such as engagement in life were related to higher self-esteem and demonstrating the co-occurrence of low self-esteem and depression. However, clear causal links have yet to be identified, and more research is needed using longitudinal designs to answer questions about trajectory

Dynamic Release of Bending Stress in Short dsDNA by Formation of a Kink and Forks

Bending with high curvature is one of the major mechanical properties of double-stranded DNA (dsDNA) that is essential for its biological functions. The emergence of a kink arising from local melting in the middle of dsDNA has been suggested as a mechanism of releasing the energy cost of bending. Herein, we report that strong bending induces two types of short dsDNA deformations, induced by two types of local melting, namely, a kink in the middle and forks at the ends, which we demonstrate using D-shaped DNA nanostructures. The two types of deformed dsDNA structures dynamically interconvert on a millisecond timescale. The transition from a fork to a kink is dominated by entropic contribution (anti-Arrhenius behavior), while the transition from a kink to a fork is dominated by enthalpic contributions. The presence of mismatches in dsDNA accelerates kink formation, and the transition from a kink to a fork is removed when the mismatch size is three base pairs.1157Ysciescopu

Popularity-Based Adaptive Content Delivery Scheme with In-Network Caching

To solve the increasing popularity of video streaming services over the Internet, recent research activities have addressed the locality of content delivery from a network edge by introducing a storage module into a router. To employ in-network caching and persistent request routing, this paper introduces a hybrid content delivery network (CDN) system combining novel content routers in an underlay together with a traditional CDN server in an overlay. This system first selects the most suitable delivery scheme (that is, multicast or broadcast) for the content in question and then allocates an appropriate number of channels based on a consideration of the content’s popularity. The proposed scheme aims to minimize traffic volume and achieve optimal delivery cost, since the most popular content is delivered through broadcast channels and the least popular through multicast channels. The performance of the adaptive scheme is clearly evaluated and compared against both the multicast and broadcast schemes in terms of the optimal in-network caching size and number of unicast channels in a content router to observe the significant impact of our proposed scheme

Entropically Driven Formation of Hierarchically Ordered Nanocomposites

Using theoretical models, we undertake the first investigation into the rich behavior that emerges when binary particle mixtures are blended with microphase-separating copolymers. We isolate an example of coupled self-assembly in such materials, where the system undergoes a nanoscale ordering of the particles along with a phase transformation in the copolymer matrix. Furthermore, the self-assembly is driven by entropic effects involving all the different components. The results reveal that entropy can be exploited to create highly ordered nanocomposites with potentially unique electronic and photonic properties. © 2002 The American Physical Society