29,855 research outputs found

    Search for Contact Interactions in the Dimuon Final State at ATLAS

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    The Standard Model has been successful in describing many fundamental aspects of particle physics. However, there are some remaining puzzles that are not explained within the context of its present framework. We discuss the possibility to discover new physics in the ATLAS Detector via a four-fermion contact interaction, much in the same way Fermi first described Weak interactions. Using a simple ratio method on dimuon events, we can set a 95% C.L. lower limit on the effective scale Lambda = 7.5 TeV (8.7 TeV) for the constructive Left-left Isoscalar Model of quark compositeness with 100 pb^-1 (200 pb^-1) of data at sqrt{s} = 10 TeV.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

    A basic lock-in amplifier experiment for the undergraduate laboratory

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    We describe a basic experiment for the undergraduate laboratory that demonstrates aspects of both, the science and the art of precision electronic measurements. The essence of the experiment is to measure the resistance of a small length of brass-wire to high accuracy using a simple voltage divider and a lock-in amplifier. By performing the measurement at different frequencies and different drive currents, one observes various random noise sources and systematic measurement effects

    Structure, bonding and morphology of hydrothermally synthesised xonotlite

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    The authors have systematically investigated the role of synthesis conditions upon the structure and morphology of xonotlite. Starting with a mechanochemically prepared, semicrystalline phase with Ca/Si=1, the authors have prepared a series of xonotlite samples hydrothermally, at temperatures between 200 and 250 degrees C. Analysis in each case was by X-ray photoelectron spectroscopy, environmental scanning electron microscopy and X-ray diffraction. The authors’ use of a much lower water/solid ratio has indirectly confirmed the ‘through solution’ mechanism of xonotlite formation, where silicate dissolution is a key precursor of xonotlite formation. Concerning the role of temperature, too low a temperature (~200 degrees C) fails to yield xonotlite or leads to increased number of structural defects in the silicate chains of xonotlite and too high a temperature (>250 degrees C) leads to degradation of the xonotlite structure, through leaching of interchain calcium. Synthesis duration meanwhile leads to increased silicate polymerisation due to diminishing of the defects in the silicate chains and more perfect crystal morphologies

    A benign, low Z electron capture agent for negative ion TPCs

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    We have identified nitromethane (CH3_3NO2_2) as an effective electron capture agent for negative ion TPCs (NITPCs). We present drift velocity and longitudinal diffusion measurements for negative ion gas mixtures using nitromethane as the capture agent. Not only is nitromethane substantially more benign than the only other identified capture agent, CS2_2, but its low atomic number will enable the use of the NITPC as a photoelectric X{}-ray polarimeter in the 1{}-10 keV band

    Macroscopic coherence effects in a mesoscopic system: Weak localization of thin silver films in an undergraduate lab

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    We present an undergraduate lab that investigates weak localization in thin silver films. The films prepared in our lab have thickness, aa, between 60-200 \AA, a mesoscopic length scale. At low temperatures, the inelastic dephasing length for electrons, LϕL_{\phi}, exceeds the thickness of the film (Lϕ≫aL_{\phi} \gg a), and the films are then quasi-2D in nature. In this situation, theory predicts specific corrections to the Drude conductivity due to coherent interference between conducting electrons' wavefunctions, a macroscopically observable effect known as weak localization. This correction can be destroyed with the application of a magnetic field, and the resulting magnetoresistance curve provides information about electron transport in the film. This lab is suitable for Junior or Senior level students in an advanced undergraduate lab course.Comment: 16 pages, 9 figures. Replaces earlier version of paper rejected by Am. J. Phys. because of too much content on vacuum systems. New version deals with the undergraduate experiment on weak localization onl

    TicTimer Web: Software for measuring tic suppression remotely

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    Woods and Himle developed a standardized tic suppression paradigm (TSP) for the experimental setting, to quantify the effects of intentional tic suppression in Tourette syndrome. We previously provided a computer program to facilitate recording tic occurrence and to automate reward delivery during the several experimental conditions of the TSP. The present article describes a web-based program that performs the same functions. Implementing this program on the web allows research sessions to be performed remotely, in tandem with a video calling program. Relevant data for each session, such as the timing of tics and dispensed rewards, are stored in plain text files for later analysis. Expected applications include research on Tourette syndrome and related disorders

    Global Update and Trends of Hidden Hunger, 1995-2011: The Hidden Hunger Index

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    Background Deficiencies in essential vitamins and minerals–also termed hidden hunger–are pervasive and hold negative consequences for the cognitive and physical development of children. Methods This analysis evaluates the change in hidden hunger over time in the form of one composite indicator–the Hidden Hunger Index (HHI)–using an unweighted average of prevalence estimates from the Nutrition Impact Model Study for anemia due to iron deficiency, vitamin A deficiency, and stunting (used as a proxy indicator for zinc deficiency). Net changes from 1995–2011 and population weighted regional means for various time periods are measured. Findings Globally, hidden hunger improved (-6.7 net change in HHI) from 1995–2011. Africa was the only region to see a deterioration in hidden hunger (+1.9) over the studied time period; East Asia and the Pacific performed exceptionally well (-13.0), while other regions improved only slightly. Improvements in HHI were mostly due to reductions in zinc and vitamin A deficiencies, while anemia due to iron deficiency persisted and even increased. Interpretation This analysis is critical for informing and tracking the impact of policy and programmatic efforts to reduce micronutrient deficiencies, to advance the global nutrition agenda, and to achieve the Millennium Development Goals (MDGs). However, there remains an unmet need to invest in gathering frequent, nationally representative, high-quality micronutrient data as we renew our efforts to scale up nutrition, and as we enter the post-2015 development agenda. Funding Preparation of this manuscript was funded by Sight and Life. There was no funding involved in the study design, data collection, analysis, or decision to publish

    Social inequalities in rural England: Impacts on young people post-2008

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThis paper investigates the cumulative impacts of the 2008 economic crisis and its aftermath (including policy changes) on young people in a sparsely populated rural area of northern England. The paper locates the research in the context of youth studies, Bourdieu's theory of practice, concepts of welfare regimes and welfare mix, and studies of the impacts of the crisis and austerity policies on the distribution of social and societal risk. The empirical findings reveal the challenges which faced young people in rural England before the financial crisis still persist. Moreover, the overwhelming reliance of young people on family for support generates further inequalities through what might be termed ‘secondary impact austerity’: young people feel indirectly and unevenly the economic effects and policy changes which impact on parents' and communities' ability to offer them support. Thus, changes to the welfare system, loss of services and less secure forms of employment exacerbate the transfer of social risk and the deepening of poverty for vulnerable groups. This is worsened in this rural area by the moral imperatives which stigmatise access to state and charitable support. Thus, moral capital and local habitus intersect with social, economic and cultural capitals in structuring inequalities.Newcastle Universit

    Peer Review in Carnegie Research Libraries

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    The review of librarians by their peers is an elemental factor in advance­ ment and continuing appointment. This article reports the results of a survey on structure, support, and expectations in place for peer review of librarians. The authors provide comparisons to previous research and discuss new information on the value placed on individual contributions in the review process. Librarian status is reviewed to uncover important differences in the specific structure of the review process and in how professional activities are weighed
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