440 research outputs found
Continuous Monitoring of Distributed Data Streams over a Time-based Sliding Window
The past decade has witnessed many interesting algorithms for maintaining
statistics over a data stream. This paper initiates a theoretical study of
algorithms for monitoring distributed data streams over a time-based sliding
window (which contains a variable number of items and possibly out-of-order
items). The concern is how to minimize the communication between individual
streams and the root, while allowing the root, at any time, to be able to
report the global statistics of all streams within a given error bound. This
paper presents communication-efficient algorithms for three classical
statistics, namely, basic counting, frequent items and quantiles. The
worst-case communication cost over a window is bits for basic counting and words for the remainings, where is the number of distributed
data streams, is the total number of items in the streams that arrive or
expire in the window, and is the desired error bound. Matching
and nearly matching lower bounds are also obtained.Comment: 12 pages, to appear in the 27th International Symposium on
Theoretical Aspects of Computer Science (STACS), 201
The stochastic evolutionary dynamics of softmax policy gradient in games
The theoretical underpinnings of multi-agent learning have recently attracted much attention. In this paper, we study the learning dynamics of the softmax policy gradient (PG) algorithm in multi-agent environments in the context of evolutionary game theory. We revisit the previous analyses based on mean dynamics and observe that previous models fail to characterize the effect of stochasticity. To this end, we propose a stochastic dynamics model to analyse the learning dynamics of PG under symmetric games. We model the parameter dynamics of the learning agent as a multidimensional Wiener process. Applying the Itô’s lemma, we obtain the corresponding policy dynamics for the agent. From that, we study the convergence behaviour of the policy dynamics under the self-play training scheme for learning in games. We work out the suffcient conditions for the stochastic stability of the pure Nash equilibrium strategy, and we evaluate the suffcient conditions for the existence of stationary distribution for strictly stable games. Moreover, we express the dynamics of the parameter distribution with the Fokker-Planck equation. In the experiments, we demonstrate that our stochastic dynamics model always provides a significantly more accurate description of the actual learning dynamics than the mean dynamics model across different games and settings
Overprotection and the psychological states of cerebral palsy patients and their caretakers in Hong Kong: A preliminary report
Objective: To examine the relation between perceived overprotection and the psychological states of cerebral palsy patients and their primary caretakers in Hong Kong. Design: Cross-sectional survey, in which data of 14 pairs of cerebral palsy patients and their caretakers were analysed. Setting: Duchess of Kent Children's Hospital, Hong Kong. Participants: Cerebral palsy patients and their primary caretakers in Hong Kong. Main outcome measures: Perceived overprotection and psychological states. Results: Nearly two thirds of the 14 patients (mean age of 15 years) and 86% of the 14 primary caretakers (mean age of 47 years) perceived various levels of overprotection. For both patients and caretakers, perceived overprotection was positively associated with anxiety and unhappiness. The patients' and caretakers' psychological states and perception of overprotection were not related to the actual motor ability of the patients. Perceived overprotection of the patients was not related to that of the caretakers. Conclusion: Caretakers should be mindful that a well-meaning move may have undesirable consequences. More support and child-rearing education should be considered for caretakers.published_or_final_versio
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OMMA enables population-scale analysis of complex genomic features and phylogenomic relationships from nanochannel-based optical maps.
BackgroundOptical mapping is an emerging technology that complements sequencing-based methods in genome analysis. It is widely used in improving genome assemblies and detecting structural variations by providing information over much longer (up to 1 Mb) reads. Current standards in optical mapping analysis involve assembling optical maps into contigs and aligning them to a reference, which is limited to pairwise comparison and becomes bias-prone when analyzing multiple samples.FindingsWe present a new method, OMMA, that extends optical mapping to the study of complex genomic features by simultaneously interrogating optical maps across many samples in a reference-independent manner. OMMA captures and characterizes complex genomic features, e.g., multiple haplotypes, copy number variations, and subtelomeric structures when applied to 154 human samples across the 26 populations sequenced in the 1000 Genomes Project. For small genomes such as pathogenic bacteria, OMMA accurately reconstructs the phylogenomic relationships and identifies functional elements across 21 Acinetobacter baumannii strains.ConclusionsWith the increasing data throughput of optical mapping system, the use of this technology in comparative genome analysis across many samples will become feasible. OMMA is a timely solution that can address such computational need. The OMMA software is available at https://github.com/TF-Chan-Lab/OMTools
Assessment of Extracts from Red Yeast Rice for Herb-Drug Interaction by in-vitro and in-vivo assays
Red yeast rice (RYR) is made by fermenting the yeast Monascus purpureus over rice. It is a source of natural red food colorants, a food garnish and a traditional medication. Results of the current study demonstrated that polar fractions of the RYR preparations contained herbal-drug interaction activity, which if left unremoved, enhanced P-glycoprotein activity and inhibited the major drug metabolizing cytochromes P450, i,e, CYP 1A2, 2C9 and 3A4. The data from Caco-2 cell absorption and animal model studies further demonstrated that the pharmacokinetic modulation effect by RYR preparations containing the polar fractions (“untreated” preparation) was greater than that from RYR preparations with the polar fractions removed (“treated” preparation). The data indicates a potential for herb-drug interactions to be present in RYR commonly sold as nutritional supplements when the polar fractions are not removed and this should be taken into consideration when RYR is consumed with medications, including verapamil
大時代的文化研究 : 馬照跑,舞照跳? = Will horse racing and dancing go on in the Great Era of Cultural Studies?
研討會分為二部分。第一部分的主題是「大時代的文化研究:馬照跑,舞照跳?」,以MCSian的論文為引旨,透過對話去思考在當前處境如何尋找出路,由鄧芝珊主持,分別由廖可兒主講〈從聯合國氣候變化大會到黃背心運動–反思「環境 vs 發展與生計」的二元對立〉,馮羚主講〈從台灣電音三太子看傳統文化的傳承與挑戰〉,譚家浚主講〈賽馬作為統治殖民手段 - 由被統治者的接受與反抗所演變成的香港賽馬文化〉,並由李小良評論及與講者進行討論
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