900 research outputs found
Cortisol levels are positively associated with pup-feeding rates in male meerkats
In societies of cooperative vertebrates, individual differences in contributions to offspring care are commonly substantial. Recent attempts to explain the causes of this variation have focused on correlations between contributions to care and the protein hormone prolactin, or the steroid hormone testosterone. However, such studies have seldom considered the importance of other hormones or controlled for non-hormonal factors that are correlative with both individual hormone levels and contributions to care. Using multivariate statistics, we show that hormone levels explain significant variation in contributions to pup-feeding by male meerkats, even after controlling for non-hormonal effects. However, long-term contributions to pup provisioning were significantly and positively correlated with plasma levels of cortisol rather than prolactin, while plasma levels of testosterone were not related to individual patterns of pup-feeding. Furthermore, a playback experiment that used pup begging calls to increase the feeding rates of male helpers gave rise to parallel increases in plasma cortisol levels, whilst prolactin and testosterone levels remained unchanged. Our findings confirm that hormones can explain significant amounts of variation in contributions to offspring feeding, and that cortisol, not prolactin, is the hormone most strongly associated with pup-feeding in cooperative male meerkats
Geophysical Exploration of Vesta
Dawn’s year-long stay at Vesta allows
comprehensive mapping of the shape, topography,
geology, mineralogy, elemental abundances, and
gravity field using it’s three instruments and highprecision
spacecraft navigation. In the current Low
Altitude Mapping Orbit (LAMO), tracking data is being
acquired to develop a gravity field expected to be
accurate to degree and order ~20 [1, 2]. Multi-angle
imaging in the Survey and High Altitude Mapping
Orbit (HAMO) has provided adequate stereo coverage
to develop a shape model accurate to ~10 m at 100 m
horizontal spatial resolution. Accurate mass determination
combined with the shape yields a more precise
value of bulk density, albeit with some uncertainty
resulting from the unmeasured seasonally-dark north
polar region. The shape and gravity of Vesta can be
used to infer the interior density structure and investigate
the nature of the crust, informing models for Vesta’s
formation and evolution
Rapidly Evolving Disk-Jet Coupling during Re-brightenings in the Black Hole Transient MAXI J1535-571
Evaluation of a Conversation Management Toolkit for Multi Agent Programming
The Agent Conversation Reasoning Engine (ACRE) is intended to aid agent
developers to improve the management and reliability of agent communication. To
evaluate its effectiveness, a problem scenario was created that could be used
to compare code written with and without the use of ACRE by groups of test
subjects.
This paper describes the requirements that the evaluation scenario was
intended to meet and how these motivated the design of the problem. Two
experiments were conducted with two separate sets of students and their
solutions were analysed using a combination of simple objective metrics and
subjective analysis. The analysis suggested that ACRE by default prevents some
common problems arising that would limit the reliability and extensibility of
conversation-handling code.
As ACRE has to date been integrated only with the Agent Factory multi agent
framework, it was necessary to verify that the problems identified are not
unique to that platform. Thus a comparison was made with best practice
communication code written for the Jason platform, in order to demonstrate the
wider applicability of a system such as ACRE.Comment: appears as Programming Multi-Agent Systems - 10th International
Workshop, ProMAS 2012, Valencia, Spain, June 5, 2012, Revised Selected Paper
Amorphization kinetics under electron irradiation
A model is brought forward of the kinetics of amorphization occurring under electron irradiation. The model is based on consideration of the phase transformations controlled by the structural relaxation of small-scale unstable atomic configurations excited by electrons.Наведено модель кінетики аморфізації під електронним випромінюванням. Модель грунтується на розгляді фазових перетворень, які контролюються структурной релаксацієй дрібномасштабних нестабільних атомних конфігурацій, які збуджуються електронами.Приведена модель кинетики аморфизации под электронным облучением. Модель основывается на рассмотрении фазовых превращений, которые контролируются структурной релаксацией мелкомасштабных нестабильных атомных конфигураций, которые возбуждаются электронами
Re-brightening of the black hole candidate MAXI J1535-571 as it transitioned back to the soft state
Prox-regularity of rank constraint sets and implications for algorithms
We present an analysis of sets of matrices with rank less than or equal to a
specified number . We provide a simple formula for the normal cone to such
sets, and use this to show that these sets are prox-regular at all points with
rank exactly equal to . The normal cone formula appears to be new. This
allows for easy application of prior results guaranteeing local linear
convergence of the fundamental alternating projection algorithm between sets,
one of which is a rank constraint set. We apply this to show local linear
convergence of another fundamental algorithm, approximate steepest descent. Our
results apply not only to linear systems with rank constraints, as has been
treated extensively in the literature, but also nonconvex systems with rank
constraints.Comment: 12 pages, 24 references. Revised manuscript to appear in the Journal
of Mathematical Imaging and Visio
Re-brightening of the black hole candidate MAXI J1535-571 as it transitioned back to the soft state
Topologically Alice Strings and Monopoles
Symmetry breaking can produce ``Alice'' strings, which alter scattered
charges and carry monopole number and charge when twisted into loops. Alice
behavior arises algebraically, when strings obstruct unbroken symmetries -- a
fragile criterion. We give a topological criterion, compelling Alice behavior
or deforming it away. Our criterion, that \pi_o(H) acts nontrivially on
\pi_1(H), links topologically Alice strings to topological monopoles. We twist
topologically Alice loops to form monopoles. We show that Alice strings of
condensed matter systems (nematic liquid crystals, helium 3A, and related
non-chiral Bose condensates and amorphous chiral superconductors) are
topologically Alice, and support fundamental monopole charge when twisted into
loops. Thus they might be observed indirectly, not as strings, but as loop-like
point defects. We describe other models, showing Alice strings failing our
topological criterion; and twisted Alice loops supporting deposited, but not
fundamental, monopole number.Comment: 2 figures; this paper consolidates preprints hep-th/0304161 and
hep-th/0304162, to appear in Phys. Rev.
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