2,720 research outputs found

    How Computational Statistics Became the Backbone of Modern Data Science

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    This first chapter serves as an introduction and overview for a collection of articles surveying the current state of the science of computational statistics. Earlier versions of most of these articles appeared in the first edition of Handbook of Computational Statistics: Concepts and Methods, published in 2004. There have been advances in all of the areas of computational statistics, so we feel that it is time to revise and update this Handbook. This introduction is a revision of the introductory chapter of the first edition.Discrete time series models, continuous time diffusion models, models with jumps, stochastic volatility, GARCH

    Student and instructor attitudes toward CALL and MALL in the L2 classroom

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    [EN] As part of an ongoing study focusing on language learner and instructor attitudes toward the use of computers and mobile devices in second language (L2) learning contexts, the authors attempt to identify to what degree language instructors value the use of computers and mobile devices in their teaching. We compare the responses of a survey administered to an “in-house” group of instructors within two faculties of a private university in Tokyo, Japan, with the responses collected from a similar survey administered to instructors solicited through various CALL organizations. The number of respondents of the “in-house” survey during the first three years was relatively low; however, in the final year was considerably much higher, with the number from both full-time and part-time staff totaling 34. The total number of survey respondents from the CALL organizations totaled 121, with the participants’ places of employment ranging from Europe to the Asia Pacific Rim. In addition to offering an interpretation of a sampling of the Likert scale items found on the surveys, the authors focus on comparing the responses offered by both groups of instructors regarding which skills they focused on in the CALL classroom, as well as what mobile applications they encouraged their students to use.http://ocs.editorial.upv.es/index.php/HEAD/HEAD18Pagel, J.; Lambacher, S.; Kikuchi, H.; Mori, S. (2018). Student and instructor attitudes toward CALL and MALL in the L2 classroom. Editorial Universitat Politècnica de València. 891-898. https://doi.org/10.4995/HEAD18.2018.8108OCS89189

    Natural antioxidants may prevent posttraumatic epilepsy: a proposal based on experimental animal studies.

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    Head injury or hemorrhagic cortical infarction results in extravasation of blood and breakdown of red blood cells and hemoglobin. Iron liberated from hemoglobin, and hemoglobin itself, are associated with the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS have been demonstrated to be involved in the mechanism of seizures induced by iron ions in the rat brain, an experimental animal model for posttraumatic epilepsy (PTE). ROS are responsible for the induction for peroxidation of neural lipids, i.e., an injury of neuronal membranes, and also could induce disorders in the excitatory and inhibitory neurotransmitters. Antioxidants, such as a phosphate diester of vitamin E and C (EPC-K1) and antiepileptic zonisamide, have been known to prevent the epileptogenic focus formation, or to attenuate seizure activities in the iron-injected rat brain. Natural antioxidants, such as alpha-tocopherol, and condensed tannins, including (-)-epigallocatechin and (-)-epigallocatechin-3-O-gallate, adenosine and its derivative, melatonin, uyaku (Lindera Strychnifolia), fermented papaya preparations, Gastrodia elata BI., and Guilingji, have been demonstrated to scavenge ROS and/or RNS and to be prophylactic for the occurrence of epileptic discharge in the iron-injected rat brain.</p

    Active Fail-Safe Micro-Array Flow Control for Advanced Embedded Propulsion Systems

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    The primary objective of this research effort was to develop and analytically demonstrate enhanced first generation active "fail-safe" hybrid flow-control techniques to simultaneously manage the boundary layer on the vehicle fore-body and to control the secondary flow generated within modern serpentine or embedded inlet S-duct configurations. The enhanced first-generation technique focused on both micro-vanes and micro-ramps highly-integrated with micro -jets to provide nonlinear augmentation for the "strength' or effectiveness of highly-integrated flow control systems. The study focused on the micro -jet mass flow ratio (Wjet/Waip) range from 0.10 to 0.30 percent and jet total pressure ratios (Pjet/Po) from 1.0 to 3.0. The engine bleed airflow range under study represents about a 10 fold decrease in micro -jet airflow than previously required. Therefore, by pre-conditioning, or injecting a very small amount of high-pressure jet flow into the vortex generated by the micro-vane and/or micro-ramp, active flow control is achieved and substantial augmentation of the controlling flow is realized

    Trinucleotide cassettes increase diversity of T7 phage-displayed peptide library

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    <p>Abstract</p> <p>Background</p> <p>Amino acid sequence diversity is introduced into a phage-displayed peptide library by randomizing library oligonucleotide DNA. We recently evaluated the diversity of peptide libraries displayed on T7 lytic phage and M13 filamentous phage and showed that T7 phage can display a more diverse amino acid sequence repertoire due to differing processes of viral morphogenesis.</p> <p>Methods</p> <p>In this study, we evaluated and compared the diversity of a 12-mer T7 phage-displayed peptide library randomized using codon-corrected trinucleotide cassettes with a T7 and an M13 12-mer phage-displayed peptide library constructed using the degenerate codon randomization method.</p> <p>Results</p> <p>We herein demonstrate that the combination of trinucleotide cassette amino acid codon randomization and T7 phage display construction methods resulted in a significant enhancement to the functional diversity of a 12-mer peptide library. This novel library exhibited superior amino acid uniformity and order-of-magnitude increases in amino acid sequence diversity as compared to degenerate codon randomized peptide libraries. Comparative analyses of the biophysical characteristics of the 12-mer peptide libraries revealed the trinucleotide cassette-randomized library to be a unique resource.</p> <p>Conclusion</p> <p>The combination of T7 phage display and trinucleotide cassette randomization resulted in a novel resource for the potential isolation of binding peptides for new and previously studied molecular targets.</p

    Southern California Seismographic Network; report to the U.S. Geological Survey, August 21, 1990

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    On August 21, 1990, the U. S. Geological Survey held a meeting to review the status of regional seismic networks in the United States. The purpose of the meeting was to provide information to the U.S.G.S. to assist them in setting priorities for future funding of seismic networks in a time of increasingly tight budgets. Each of the networks was therefore asked to prepare a report describing their goals and accomplishments. Three specific questions were raised: how the objectives of the network have been met, the potential for future productivity and opportunities for additional funding

    Preliminary Report on the 1995 Ridgecrest Earthquake Sequence in Eastern California

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    The Ridgecrest earthquake sequence began on 17 August 1995 with a M_L 5.4 earthquake. As of October 3, 1995, the Southern California Seismic Network (SCSN) had recorded over 4,500 events in the sequence, with eight events of M ≥ 4.0. These earthquakes are occurring along the eastern edge of the Indian Wells Valley along a small stretch of the thoroughgoing Eastern California Shear Zone (ECSZ). Previous large events within the ECSZ include the 1992 (M_w 7.3) Landers earthquake sequence and the 1872 (M 7.6) Owens Valley earthquake. The only large earthquake to occur near Indian Wells Valle, was the 1946 Walker Pass (M 6.0) earthquake on an unknown fault in the Sierra Nevada mountains to the west. The ECSZ transfers some of the relative motion between the North America and Pacific Plates away from the San Andreas fault to the western Great Basin of the Basin and Range province

    A Convergent Method for Calculating the Properties of Many Interacting Electrons

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    A method is presented for calculating binding energies and other properties of extended interacting systems using the projected density of transitions (PDoT) which is the probability distribution for transitions of different energies induced by a given localized operator, the operator on which the transitions are projected. It is shown that the transition contributing to the PDoT at each energy is the one which disturbs the system least, and so, by projecting on appropriate operators, the binding energies of equilibrium electronic states and the energies of their elementary excitations can be calculated. The PDoT may be expanded as a continued fraction by the recursion method, and as in other cases the continued fraction converges exponentially with the number of arithmetic operations, independent of the size of the system, in contrast to other numerical methods for which the number of operations increases with system size to maintain a given accuracy. These properties are illustrated with a calculation of the binding energies and zone-boundary spin- wave energies for an infinite spin-1/2 Heisenberg chain, which is compared with analytic results for this system and extrapolations from finite rings of spins.Comment: 30 pages, 4 figures, corrected pd
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