1,867 research outputs found
Combinatorial batch codes
In this paper, we study batch codes, which were introduced by Ishai, Kushilevitz, Ostrovsky and Sahai in [4]. A batch code specifies a method to distribute a database of [n] items among [m] devices (servers) in such a way that any [k] items can be retrieved by reading at most [t] items from each of the servers. It is of interest to devise batch codes that minimize the total storage, denoted by [N] , over all [m] servers.
We restrict out attention to batch codes in which every server stores a subset of the items. This is purely a combinatorial problem, so we call this kind of batch code a ''combinatorial batch code''. We only study the special case [t=1] , where, for various parameter situations, we are able to present batch codes that are optimal with respect to the storage requirement, [N] . We also study uniform codes, where every item is stored in precisely [c] of the [m] servers (such a code is said to have rate [1/c] ). Interesting new results are presented in the cases [c = 2, k-2] and [k-1] . In addition, we obtain improved existence results for arbitrary fixed [c] using the probabilistic method
Probing fundamental physics with pulsars
Pulsars provide a wealth of information about General Relativity, the
equation of state of superdense matter, relativistic particle acceleration in
high magnetic fields, the Galaxy's interstellar medium and magnetic field,
stellar and binary evolution, celestial mechanics, planetary physics and even
cosmology. The wide variety of physical applications currently being
investigated through studies of radio pulsars rely on: (i) finding interesting
objects to study via large-scale and targeted surveys; (ii) high-precision
timing measurements which exploit their remarkable clock-like stability. We
review current surveys and the principles of pulsar timing and highlight
progress made in the rotating radio transients, intermittent pulsars, tests of
relativity, understanding pulsar evolution, measuring neutron star masses and
the pulsar timing array.Comment: 6 pages, 1 figure, to appear in the proceedings of IAU XXVII GA - JD3
- Neutron Stars: Timing in Extreme Environments XXVII IAU General Assembly,
Rio de Janeiro, Brazil, 3-14 August 200
Technology Assisted Reviews: Finding the Last Few Relevant Documents by Asking Yes/No Questions to Reviewers
The goal of a technology-assisted review is to achieve high recall with low
human effort. Continuous active learning algorithms have demonstrated good
performance in locating the majority of relevant documents in a collection,
however their performance is reaching a plateau when 80\%-90\% of them has been
found. Finding the last few relevant documents typically requires exhaustively
reviewing the collection. In this paper, we propose a novel method to identify
these last few, but significant, documents efficiently. Our method makes the
hypothesis that entities carry vital information in documents, and that
reviewers can answer questions about the presence or absence of an entity in
the missing relevance documents. Based on this we devise a sequential Bayesian
search method that selects the optimal sequence of questions to ask. The
experimental results show that our proposed method can greatly improve
performance requiring less reviewing effort.Comment: This paper is accepted by SIGIR 201
Continuing to Advance Warranting Theory: Weight, Time, and Testing the Warranting Value Scale
Warranting theory asserts that individuals are likely to form impressions of others based on information found online that is not easily manipulated by the target of the information. Because existing literature has found inconsistent support for warranting theory, this dissertation conducted a study of warranting theory both through using traditional warranting theory ideas and through testing the possibility of other variables playing a role in the impression formation process. Participants (N = 330) viewed mock websites with information about a professor and then reported on their impressions of the website and the instructor. About 18 days later, participants completed a delayed questionnaire about their impressions of the instructor. Modeling the first set of hypotheses after traditional tests of warranting theory, this dissertation found support for warranting theory. Other-generated content was associated with higher perceived warranting value than self-generated content; a connection that was assumed, but never explicitly tested in existing literature. The role of perceived warranting value in the relationship between source and impression was partially supported, while support was not found for the weight, or importance, of information within the relationship between source and impression. Over time, impressions converged, consistent with sleeper effect literature
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