175,882 research outputs found
Combining Semi-Analytic Models of Galaxy Formation with Simulations of Galaxy Clusters: the Need for AGN Heating
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
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
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
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 -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
- …