2,851 research outputs found

    Map Making

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    Regulating to Achieve Stability in the Domain of High-Frequency Trading

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    High-frequency trading has become a darling of capital markets debate. This debate thrives because the true and long-lasting effects of high-frequency trading are still unknown. On one hand, high-frequency trading evidences recent and powerful advances in trading technology; on the other, it is said to harness speed at the expense of fairness, prudence, and stability. In part because of this duality, the regulation of high-frequency trading in the United States has been slow to develop. Other nations, however, have been quicker to react and to promulgate laws that directly, or indirectly, affect high-frequency trading. This Note explores the legal responses to high-frequency trading across a multitude of nations. Drawing on insights from this global landscape, it proposes domestic structural reforms—such as a variable tick size regime, discrete call markets, and experimental order taxes— that would allow the positive potential of high-frequency trading to be realized, while minimizing its impact upon market stability

    Microbial gene abundance and expression patterns across a river to ocean salinity gradient

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    © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 10 (2015): e0140578, doi: 10.1371/journal.pone.0140578.Microbial communities mediate the biogeochemical cycles that drive ecosystems, and it is important to understand how these communities are affected by changing environmental conditions, especially in complex coastal zones. As fresh and marine waters mix in estuaries and river plumes, the salinity, temperature, and nutrient gradients that are generated strongly influence bacterioplankton community structure, yet, a parallel change in functional diversity has not been described. Metagenomic and metatranscriptomic analyses were conducted on five water samples spanning the salinity gradient of the Columbia River coastal margin, including river, estuary, plume, and ocean, in August 2010. Samples were pre-filtered through 3 μm filters and collected on 0.2 μm filters, thus results were focused on changes among free-living microbial communities. Results from metagenomic 16S rRNA sequences showed taxonomically distinct bacterial communities in river, estuary, and coastal ocean. Despite the strong salinity gradient observed over sampling locations (0 to 33), the functional gene profiles in the metagenomes were very similar from river to ocean with an average similarity of 82%. The metatranscriptomes, however, had an average similarity of 31%. Although differences were few among the metagenomes, we observed a change from river to ocean in the abundance of genes encoding for catabolic pathways, osmoregulators, and metal transporters. Additionally, genes specifying both bacterial oxygenic and anoxygenic photosynthesis were abundant and expressed in the estuary and plume. Denitrification genes were found throughout the Columbia River coastal margin, and most highly expressed in the estuary. Across a river to ocean gradient, the free-living microbial community followed three different patterns of diversity: 1) the taxonomy of the community changed strongly with salinity, 2) metabolic potential was highly similar across samples, with few differences in functional gene abundance from river to ocean, and 3) gene expression was highly variable and generally was independent of changes in salinity.This study was carried out within the context of the Science and Technology Center for Coastal Margin Observation & Prediction (CMOP) supported by the National Science Foundation, grant number OCE-0424602 to Antonio Baptista (http://www.stccmop.org)

    Cooperating Teachers’ Perceptions of Pedagogical Importance, Competence, and Programmatic Need: A Frontline Assessment of Agricultural Student Teachers

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    The purpose of this descriptive study was to determine, as witnessed by cooperating teachers, what learning gaps student teachers brought to the student teaching experience “Supervision of student teachers during student teaching is a very important exercise in teacher training” (Thobega & Miller, 2008, p. 65)..Cooperating teachers spend 10 plus weeks observing student teachers of agricultural education in [state]. One may argue that the cooperating teacher is the best judge of success when looking at the student teacher. Cooperating teachers believed using computers and multimedia in classroom teaching was a strength student teachers possessed. The cooperating teachers felt that the major weaknesses included conducting parent-teacher conferences and adult programs. The findings of this study also indicate that the pre-service teachers need additional preparation in developing teaching skills in managing student behavior problems, motivating students to learn, teaching students to think critically and creatively, and conducting parent-teacher conferences

    Longitudinal Combustion Instabilities in Ramjet Engines: Identification of Acoustic Modes

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    Longitudinal combustion instabilities in liquid-fueled ramjet engines have been investigated with attention focused on determination of the acoustic mode structures. Detailed pressure measurements, including both amplitude and phase, were made at ten positions spanning the length of the engine. The experimental data have been analyzed using two linear acoustic models. Four distinct modes were observed for various inlet/combustor combinations. These results help identify the mechanisms exciting low-frequency pressure oscillations in ramjet engines

    Tegument Assembly and Secondary Envelopment of Alphaherpesviruses.

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    Alphaherpesviruses like herpes simplex virus are large DNA viruses characterized by their ability to establish lifelong latent infection in neurons. As for all herpesviruses, alphaherpesvirus virions contain a protein-rich layer called "tegument" that links the DNA-containing capsid to the glycoprotein-studded membrane envelope. Tegument proteins mediate a diverse range of functions during the virus lifecycle, including modulation of the host-cell environment immediately after entry, transport of virus capsids to the nucleus during infection, and wrapping of cytoplasmic capsids with membranes (secondary envelopment) during virion assembly. Eleven tegument proteins that are conserved across alphaherpesviruses have been implicated in the formation of the tegument layer or in secondary envelopment. Tegument is assembled via a dense network of interactions between tegument proteins, with the redundancy of these interactions making it challenging to determine the precise function of any specific tegument protein. However, recent studies have made great headway in defining the interactions between tegument proteins, conserved across alphaherpesviruses, which facilitate tegument assembly and secondary envelopment. We summarize these recent advances and review what remains to be learned about the molecular interactions required to assemble mature alphaherpesvirus virions following the release of capsids from infected cell nuclei.HSV-1 research in the laboratory of CMC is supported by the Leverhulme Trust (Grant RPG-2012-793) and the Biotechnology and Biological Sciences Research Council (Grant BB/M021424/1). SCG is a Sir Henry Dale Fellow jointly funded by the Wellcome Trust and the Royal Society (Grant Number 098406/Z/12/Z)This is the final version of the article. It first appeared from MDPI via http://dx.doi.org/10.3390/v709286

    Evaluating Amazon\u27s Mechanical Turk as a Tool for Experimental Behavioral Research

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    Amazon Mechanical Turk (AMT) is an online crowdsourcing service where anonymous online workers complete web-based tasks for small sums of money. The service has attracted attention from experimental psychologists interested in gathering human subject data more efficiently. However, relative to traditional laboratory studies, many aspects of the testing environment are not under the experimenter\u27s control. In this paper, we attempt to empirically evaluate the fidelity of the AMT system for use in cognitive behavioral experiments. These types of experiment differ from simple surveys in that they require multiple trials, sustained attention from participants, comprehension of complex instructions, and millisecond accuracy for response recording and stimulus presentation. We replicate a diverse body of tasks from experimental psychology including the Stroop, Switching, Flanker, Simon, Posner Cuing, attentional blink, subliminal priming, and category learning tasks using participants recruited using AMT. While most of replications were qualitatively successful and validated the approach of collecting data anonymously online using a web-browser, others revealed disparity between laboratory results and online results. A number of important lessons were encountered in the process of conducting these replications that should be of value to other researchers

    PACS-1 binding to adaptors is required for acidic cluster motif-mediated protein traffic

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