1,649 research outputs found
Testing bulls for breeding soundness
New tests are available to ensure that bulls are fertile
Choosing a calcium supplement for sheep fed cereal grains
Sheep fed cereal grains as an energy source over summer usually need added calcium because cereal grains are generally low in calcium (for example, 0.03 per cent calcium compared to 0.26 per cent phosphorus), and there may not be a natural source such as clover, weeds, leafy stubble or edible bush in the paddock.
The safestt and most effective calcium supplement is finely ground limestone added to the feed, but some farmers have used other sources of calcium such as gypsum and superphosphate in this manner
Black holes in asymptotically Lifshitz spacetimes with arbitrary critical exponent
Recently, a class of gravitational backgrounds in 3+1 dimensions have been
proposed as holographic duals to a Lifshitz theory describing critical
phenomena in 2+1 dimensions with critical exponent . We numerically
explore black holes in these backgrounds for a range of values of . We find
drastically different behavior for and
() the Lifshitz fixed point is repulsive (attractive) when going to larger
radial parameter . For the repulsive backgrounds, we find a continuous
family of black holes satisfying a finite energy condition. However, for
we find that the finite energy condition is more restrictive, and we expect
only a discrete set of black hole solutions, unless some unexpected
cancellations occur. For all black holes, we plot temperature as a function
of horizon radius . For we find that this curve
develops a negative slope for certain values of possibly indicating a
thermodynamic instability.Comment: 23 pages, 6 figures, references corrected, graphs made readable in
greyscal
Feynman Path Integral on the Noncommutative Plane
We formulate Feynman path integral on a non commutative plane using coherent
states. The propagator for a free particle exhibits UV cut-off induced by the
parameter of non commutativity.Comment: 7pages, latex 2e, no figures. Accepted for publication on J.Phys.
First Order Description of Black Holes in Moduli Space
We show that the second order field equations characterizing extremal
solutions for spherically symmetric, stationary black holes are in fact implied
by a system of first order equations given in terms of a prepotential W. This
confirms and generalizes the results in [14]. Moreover we prove that the
squared prepotential function shares the same properties of a c-function and
that it interpolates between M^2_{ADM} and M^2_{BR}, the parameter of the
near-horizon Bertotti-Robinson geometry. When the black holes are solutions of
extended supergravities we are able to find an explicit expression for the
prepotentials, valid at any radial distance from the horizon, which reproduces
all the attractors of the four dimensional N>2 theories. Far from the horizon,
however, for N-even our ansatz poses a constraint on one of the U-duality
invariants for the non-BPS solutions with Z \neq 0. We discuss a possible
extension of our considerations to the non extremal case.Comment: Some points clarified, a comment on the interpretation of the
prepotential W in terms of c-function added, typos corrected. Version to
appear on JHE
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Observing Serendipity in Digital Information Environments
We often interact with digital information environments to find useful information. But sometimes useful information finds us unexpectedly, propelling us in new and exciting directions. We might come across information serendipitously when looking for information on something else, or when we are not looking for anything in particular. In previous studies, people have self-reported that they come across information serendipitously. However, there has been limited success in directly observing people doing so. To see if we could have more success, we conducted naturalistic observations of 45 users interacting with different types of digital information environments. Without priming them about serendipity, we asked the users to conduct self-chosen naturalistic information tasks, which varied from broad tasks such as browsing online news to narrow tasks such as finding a particular product to buy. We noted several examples where users either 1) stated they were looking for information on a particular topic or product and unexpectedly found useful/potentially useful information about something else or 2) unexpectedly found useful/potentially useful information when not looking for anything in particular. Our findings suggest that, with a carefully-considered approach, serendipity-related information interaction behaviour can be directly observed. Direct observation allows designers of digital information environments to better understand this behaviour and use this understanding to reason about ways of designing new or improving existing support for serendipity
Holographic description of D3-branes in flat space
We describe a scheme for constructing the holographic dual of the full
D3-brane geometry with charge by embedding it into a large anti-de Sitter
space of size . Such a geometry is realized in a multi-center anti-de Sitter
geometry which admits a simple field theory interpretation as gauge
theory broken to . We find that the characteristic size of
the D3-brane geometry is of order where is the scale of
the Higgs. By choosing to be much larger than , the scale of the
D3-brane metric can be well separated from the Higgs scale in the radial
coordinate. We generalize the holographic energy-distance relation and estimate
the characteristic energy scale associated with these radial scales, and find
that the relation becomes effectively independent in the range
. This implies that all detailed structure of the
D3-brane geometry is encoded in the fine structure of the boundary gauge theory
at around the Higgs scale.Comment: 8 pages, 1 eps figur
Black Rings, Supertubes, and a Stringy Resolution of Black Hole Non-Uniqueness
In order to address the issues raised by the recent discovery of
non-uniqueness of black holes in five dimensions, we construct a solution of
string theory at low energies describing a five-dimensional spinning black ring
with three charges that can be interpreted as D1-brane, D5-brane, and momentum
charges. The solution possesses closed timelike curves (CTCs) and other
pathologies, whose origin we clarify. These pathologies can be avoided by
setting any one of the charges, e.g. the momentum, to zero. We argue that the
D1-D5-charged black ring, lifted to six dimensions, describes the thermal
excitation of a supersymmetric D1-D5 supertube, which is in the same U-duality
class as the D0-F1 supertube. We explain how the stringy microscopic
description of the D1-D5 system distinguishes between a spherical black hole
and a black ring with the same asymptotic charges, and therefore provides a
(partial) resolution of the non-uniqueness of black holes in five dimensions.Comment: 33 pages, 1 figur
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