64,179 research outputs found

    Constructing cell data for diagram algebras

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    We show how the treatment of cellularity in families of algebras arising from diagram calculi, such as Jones' Temperley--Lieb wreaths, variants on Brauer's centralizer algebras, and the contour algebras of Cox et al (of which many algebras are special cases), may be unified using the theory of tabular algebras. This improves an earlier result of the first author (whose hypotheses covered only the Brauer algebra from among these families).Comment: Approximately 38 pages, AMSTeX. Revised in light of referee comments. To appear in the Journal of Pure and Applied Algebr

    Modified hydraulic braking system limits angular deceleration to safe values

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    Conventional spring actuated, hydraulically released, fail-safe disk braking system is modified to control the angular deceleration of a massive antenna. The hydraulic system provides an immediate preset pressure to the spring-loaded brake shoes and holds it at this value to decelerate the antenna at the desired rate

    Ballistic transport is dissipative: the why and how

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    In the ballistic limit, the Landauer conductance steps of a mesoscopic quantum wire have been explained by coherent and dissipationless transmission of individual electrons across a one-dimensional barrier. This leaves untouched the central issue of conduction: a quantum wire, albeit ballistic, has finite resistance and so must dissipate energy. Exactly HOW does the quantum wire shed its excess electrical energy? We show that the answer is provided, uniquely, by many-body quantum kinetics. Not only does this inevitably lead to universal quantization of the conductance, in spite of dissipation; it fully resolves a baffling experimental result in quantum-point-contact noise. The underlying physics rests crucially upon the action of the conservation laws in these open metallic systems.Comment: Invited Viewpoint articl

    New Experiments in Minority Voter Mobilization: Second in a Series of Reports on the California Votes Initiative

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    During the first phase of the California Votes Initiative, spanning elections from June 2006 to March 2007, participating community-based organizations personally contacted over 82,000 low-propensity voters, through strategies such as door-to-door outreach and phone calls, plus reached an additional 100,000 voters through less direct methods, such as voter forums and messages to congregations. This outreach inspired many to participate in the electoral process for the first time. The initiative evaluation team worked with the community organizations to imbed field experiments into their outreach efforts, comparing turnout among those targeted for contact and those assigned to control groups. This resulted in strong empirical support for a series of best practices that were detailed in a September 2007 report.1 A second phase of the initiative has continued this path-breaking research with further field experiments in the February and June 2008 elections, with more planned for November 2008. This report briefly reviews the results from the first phase of the initiative, adds findings from February 2008 and June 2008 as available,2 and outlines the follow-up studies planned for November 2008. Many findings from the first phase were confirmed, and the two rounds of experiments conducted so far this year provide valuable refinements to the list of best practices established in that earlier report. 1 Michelson, Melissa R., Lisa Garcia Bedolla and Donald P. Green. 2007. "New Experiments in Minority Voter Mobilization: A Report on the California Votes Initiative" (San Francisco, CA: The James Irvine Foundation). Available at www.irvine.org. 2 In many counties, particularly large ones such as Los Angeles, voting information is not released until several months after an election

    New Experiments in Minority Voter Mobilization: A Report on the California Votes Initiative

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    Evaluates the effectiveness of efforts in California to mobilize voters in communities with significant low-income and minority populations

    New Experiments in Minority Voter Mobilization: Third and Final Report on the California Votes Initiative

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    This report offers new insights about voter mobilization strategies used in our California Votes Initiative. Launched in 2006, the initiative supported nine nonprofit organizations as they reached out to infrequent voters in low-income and ethnic communities in the San Joaquin Valley and parts of Southern California. This publication, the third and final report on the initiative, summarizes findings from the entirety of the project's experiments. It examines the long-term effects of voter mobilization and the effects of specific approaches, such as canvassing and phone calls, on voter attitudes toward politics and political engagement. Qualitative analyses explore the components of a successful get-out-the-vote campaign and identify five practices organizations of many types may use to increase turnout

    Getting diverse students and staff to talk about integration on campus, and what they say when they do: A UK-India collaborative case study.

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    This paper reports the early stages of a UKIERI-funded project, ‘Widening Participation: Diversity, isolation or integration in Higher Education?’.The project is concerned with greater equity, social justice, community and social cohesion within the current globalised, market oriented context of higher education (HE), and with enabling students to be better prepared for, and thrive in social networks and work-related arenas which are increasingly diverse, multicultural, interdependent and global. The main aim of this 3 year project is to explore the nature of social cohesion, integration and separation, diversity, equality and discrimination experienced by diverse, minority, disadvantaged and under-represented students attending HE in UK and India. Group stereotypes are often subconsciously held, emerging into consciousness only when they appear confirmed or confounded by personal experience or public events. Where there is little knowledge or personal experience then reliance upon group stereotypes is more likely (Kunda & Thagard, 1996). This can impact upon student and staff expectations of, responses to, and interactions with each other. Individual students’ experiences and perceptions lie at the core of this project, but the ultimate purpose is to illuminate our understanding as to how these are mediated, shaped and formed, in relation to and in interaction with the structures and contextual features of the educational environments in which they, as students, are located. It is thus framed by socio-cultural rather than psychological or therapeutic theories and is located within a social-constructivist perspective (Moore, 2000). Social constructivism facilitates the development of improved understandings of educational and social environments that shape rather than determine individual dispositions towards social diversity encountered on campus. It is highly suited to the understanding of perceptions, and exploring resonances with actions, reactions and interactions. The initial stage of this project involved inviting students and staff (academic and support staff) from five HE colleges and universities in England and India to keep a record (written and photographic) of what for them seemed to be important and relevant events relating to what they saw, heard, did and experienced on campus for a period of 1 month, in teaching, learning and social situations; namely interactions in classes and social settings; what seem to be good experiences and what seem to be negative ones; how and if their particular knowledge and experiences were used, valued and incorporated into their HE experience and learning or how they were negated. A sample size of 90 record keepers was sought across the participating institutions. Getting that sample presented significant difficulties to all but one of the participating institutions, and raised questions about • the methods initially adopted, • the general willingness of students and staff to address and share issues relating to diversity, equality, social cohesion and integration on HE campuses with researchers • cultural differences in accessing respondents to take part in the research Additional data collection methods were adopted and by January 2009 the intended sample size almost met. This paper will address the problems encountered in undertaking the first stage of this research and present initial findings from the data that were eventually obtained

    Newtonian and Relativistic Cosmologies

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    Cosmological N-body simulations are now being performed using Newtonian gravity on scales larger than the Hubble radius. It is well known that a uniformly expanding, homogeneous ball of dust in Newtonian gravity satisfies the same equations as arise in relativistic FLRW cosmology, and it also is known that a correspondence between Newtonian and relativistic dust cosmologies continues to hold in linearized perturbation theory in the marginally bound/spatially flat case. Nevertheless, it is far from obvious that Newtonian gravity can provide a good global description of an inhomogeneous cosmology when there is significant nonlinear dynamical behavior at small scales. We investigate this issue in the light of a perturbative framework that we have recently developed, which allows for such nonlinearity at small scales. We propose a relatively straightforward "dictionary"---which is exact at the linearized level---that maps Newtonian dust cosmologies into general relativistic dust cosmologies, and we use our "ordering scheme" to determine the degree to which the resulting metric and matter distribution solve Einstein's equation. We find that Einstein's equation fails to hold at "order 1" at small scales and at "order Ďľ\epsilon" at large scales. We then find the additional corrections to the metric and matter distribution needed to satisfy Einstein's equation to these orders. While these corrections are of some interest in their own right, our main purpose in calculating them is that their smallness should provide a criterion for the validity of the original dictionary (as well as simplified versions of this dictionary). We expect that, in realistic Newtonian cosmologies, these additional corrections will be very small; if so, this should provide strong justification for the use of Newtonian simulations to describe relativistic cosmologies, even on scales larger than the Hubble radius.Comment: 35 pages; minor change

    A Review of the Monitoring of Market Power The Possible Roles of TSOs in Monitoring for Market Power Issues in Congested Transmission Systems

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    The paper surveys the literature and publicly available information on market power monitoring in electricity wholesale markets. After briefly reviewing definitions, strategies and methods of mitigating market power we examine the various methods of detecting market power that have been employed by academics and market monitors/regulators. These techniques include structural and behavioural indices and analysis as well as various simulation approaches. The applications of these tools range from spot market mitigation and congestion management through to long-term market design assessment and merger decisions. Various market-power monitoring units already track market behaviour and produce indices. Our survey shows that these units collect a large amount of data from various market participants and we identify the crucial role of the transmission system operators with their access to dispatch and system information. Easily accessible and comprehensive data supports effective market power monitoring and facilitates market design evaluation. The discretion required for effective market monitoring is facilitated by institutional independence.Electricity, liberalisation, market power, regulation
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