175,526 research outputs found

    Combining Semi-Analytic Models of Galaxy Formation with Simulations of Galaxy Clusters: the Need for AGN Heating

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    We present hydrodynamical N-body simulations of clusters of galaxies with feedback taken from semi-analytic models of galaxy formation. The advantage of this technique is that the source of feedback in our simulations is a population of galaxies that closely resembles that found in the real universe. We demonstrate that, to achieve the high entropy levels found in clusters, active galactic nuclei must inject a large fraction of their energy into the intergalactic/intracluster media throughout the growth period of the central black hole. These simulations reinforce the argument of Bower et al. (2008), who arrived at the same conclusion on the basis of purely semi-analytic reasoning.Comment: 4 pages, 1 figure. To appear in the proceedings of "The Monster's Fiery Breath", Eds. Sebastian Heinz and Eric Wilcots (AIP conference series

    Controlled Environment Agriculture: A Pilot Project

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    The controlled-environment agricultural (CEA) project discussed in this report was first conceived for the Wildwood Air Force Station in Kenai, Alaska, in 1972. The region contained high unemployment and a U.S. Air Force Station that had just closed. The Kenai Native Association, Inc. (KNA), was to take possession of the Air Force Station through land transfers associated with the Alaska Native Claims Settlement Act, and this corporation was interested in expanding business and employment opportunities for local people. The University of Alaska Agricultural Experiment Station (AES) contacted KNA to determine if it had a facility which might be adaptable for use in a research and development program in controlled- 1 environment agriculture. It was determined that such a facility was available. Subsequently, AES and KNA contacted the General Electric Company (GE) in Syracuse, New York, to determine its interest in such a project. GE had extensive background in lighting technology and environmental control systems and the engineering capability to develop a total system for CEA production. It was agreed that GE would provide technological expertise and AES would provide horticultural and economic expertise for the growing and marketing of a variety of salad crops. KNA would manage the project, employ the nontechnical people, and provide the building. The Wildwood site was selected because it contained two buildings which were thought to be well suited for CEA production. One building would provide sufficient inside space for a 1/4-acre pilot production plant, nine small research modules , a laboratory , offices, a training area, and space for preparing the crop for shipping. A second building near the first contained three diesel generators which were to be converted to natural gas to provide power for the production facility.The Controlled Environment Agriculture Project at Wildwood Village, Kenai, Alaska, spanned a period of five years. During that time, three agencies: Kenai Native Association, Inc.; General Electric Company; and University of Alaska Agricultural Experiment Station , were responsible for the management, research, and production activities. Many persons from these agencies who participated in all phases of the project are acknowledged for their participation and support. This report summarizes work began in 1972 and concluded in 1977 on controlled-environment agriculture in facilities located at Wildwood Village, Kenai, Alaska, managed by the Kenai Native Association , Inc. The authors wish to express their appreciation to all those who have participated in the preparation of this bulletin. Particular acknowledgment is given to: Dr. Gerald Carlson, U.S .D.A., Beltsville, Maryland; Dr. Donald Dinkel, University of Alaska, Agricultural Experiment Station; Dr. Delbert Hemphill, Oregon State University ; John Monfor, Kenai Native Association, Inc.; Dr. Eion Scott, General Electric Company; and Dr. Norman Whittlesey, Washington State University, who thoroughly reviewed the contract document

    So what do we do with the rest of the day? Going beyond the pre-shot routine in professional golf

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    Optimally focused attention has been shown to be a key psychological characteristic for peak performance in golf; a feature commonly achieved with a pre-shot routine. However, research to date has yet to address how a golfer’s attention should best shift across the broader period of a whole game, or even including pre-event preparations, to support the pre-shot process and, ultimately, performance. Reflecting this knowledge gap, the present review aims to clarify current conceptual understanding and best practice against this wider perspective on attentional control, as well as highlight areas which must be considered for advances to be made. Specifically, research is required on the cognitive, behavioral, and temporal elements of routines used between shots and holes. Furthermore, to manage the attentional demands of the entire golf performance experience, such investigation also needs to explore the critical role of the support team and pre-tournament planning

    Ambient connections realising conformal Tractor holonomy

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    For a conformal manifold we introduce the notion of an ambient connection, an affine connection on an ambient manifold of the conformal manifold, possibly with torsion, and with conditions relating it to the conformal structure. The purpose of this construction is to realise the normal conformal tractor holonomy as affine holonomy of such a connection. We give an example of an ambient connection for which this is the case, and which is torsion free if we start the construction with a C-space, and in addition Ricci-flat if we start with an Einstein manifold. Thus for a CC-space this example leads to an ambient metric in the weaker sense of \v{C}ap and Gover, and for an Einstein space to a Ricci-flat ambient metric in the sense of Fefferman and Graham.Comment: 17 page
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