872 research outputs found
Statistical interaction modeling of bovine herd behaviors
While there has been interest in modeling the group behavior of herds or flocks, much of this work has focused on simulating their collective spatial motion patterns which have not accounted for individuality in the herd and instead assume a homogenized role for all members or sub-groups of the herd. Animal behavior experts have noted that domestic animals exhibit behaviors that are indicative of social hierarchy: leader/follower type behaviors are present as well as dominance and subordination, aggression and rank order, and specific social affiliations may also exist. Both wild and domestic cattle are social species, and group behaviors are likely to be influenced by the expression of specific social interactions. In this paper, Global Positioning System coordinate fixes gathered from a herd of beef cows tracked in open fields over several days at a time are utilized to learn a model that focuses on the interactions within the herd as well as its overall movement. Using these data in this way explores the validity of existing group behavior models against actual herding behaviors. Domain knowledge, location geography and human observations, are utilized to explain the causes of these deviations from this idealized behavior
Metatarsophalangeal joint pain in psoriatic arthritis: a cross-sectional study
Methods. Thirty-four consecutive patients with PsA (mean age 45.3 years, 65% female, mean disease duration 9.9 years) and 22 control participants (mean age 37.9 years, 64% female) underwent clinical and US examination to determine the presence of pain, swelling, synovitis, erosions, effusions and submetatarsal bursae at the MTP joints. Mean barefoot peak plantar pressures were determined at each MTP joint. Levels of pain, US-determined pathology and peak pressures were compared between groups. Binary logistic regression was used to identify demographic, clinical examination-derived, US-derived and plantar pressure predictors of pain at the MTP joints in the PsA group.
Results. The presence of pain, deformity, synovitis, erosions (P < 0.001) and submetatarsal bursae and peak plantar pressure at MTP 3 (P < 0.05) were significantly higher in the PsA group. MTP joint pain in PsA was independently predicted by high BMI, female gender and the presence of joint subluxation, synovitis and erosion.
Conclusion. These results suggest local inflammatory and structural factors, together with systemic factors (gender, BMI), are predominantly responsible for painful MTP joints in PsA, with no clear role for plantar pressure characteristics
Magnetization of small lead particles
The magnetization of an ensemble of isolated lead grains of sizes ranging
from below 6 nm to 1000 nm is measured. A sharp disappearance of Meissner
effect with lowering of the grain size is observed for the smaller grains. This
is a direct observation by magnetization measurement of the occurrence of a
critical particle size for superconductivity, which is consistent with
Anderson's criterion.Comment: 7 pages, 5 figures, Submitted to PR
Constraints on narrow exotic states from K+p and K0_Lp scattering data
We consider the effect of exotic S=+1 resonances Theta+ and Theta++ on K+p
elastic scattering data (total cross section) and the process K0_Lp-->K0_Sp.
Data near the observed Theta+(1540) are examined for evidence of additional
states. The width limit for a Theta++ state is reconsidered and shown to be
much less than 1 MeV.Comment: 4 pages, 3 eps figures; minor corrections, one fig adde
Surface-reconstructed Icosahedral Structures for Lead Clusters
We describe a new family of icosahedral structures for lead clusters. In
general, structures in this family contain a Mackay icosahedral core with a
reconstructed two-shell outer-layer. This family includes the anti-Mackay
icosahedra, which have have a Mackay icosahedral core but with most of the
surface atoms in hexagonal close-packed positions. Using a many-body glue
potential for lead, we identify two icosahedral structures in this family which
have the lowest energies of any known structure in the size range from 900 to
15000 lead atoms. We show that these structures are stabilized by a feature of
the many-body glue part of the interatomic potential.Comment: 9 pages, 8 figure
A novel isolator-based system promotes viability of human embryos during laboratory processing
In vitro fertilisation (IVF) and related technologies are arguably the most challenging of all cell culture applications. The starting material is a single cell from which one aims to produce an embryo capable of establishing a pregnancy eventually leading to a live birth. Laboratory processing during IVF treatment requires open manipulations of gametes and embryos, which typically involves exposure to ambient conditions. To reduce the risk of cellular stress, we have developed a totally enclosed system of interlinked isolator-based workstations designed to maintain oocytes and embryos in a physiological environment throughout the IVF process. Comparison of clinical and laboratory data before and after the introduction of the new system revealed that significantly more embryos developed to the blastocyst stage in the enclosed isolator-based system compared with conventional open-fronted laminar flow hoods. Moreover, blastocysts produced in the isolator-based system contained significantly more cells and their development was accelerated. Consistent with this, the introduction of the enclosed system was accompanied by a significant increase in the clinical pregnancy rate and in the proportion of embryos implanting following transfer to the uterus. The data indicate that protection from ambient conditions promotes improved development of human embryos. Importantly, we found that it was entirely feasible to conduct all IVF-related procedures in the isolator-based workstations
Coalescence of nanoscale metal clusters: Molecular-dynamics study
We study the coalescence of nanoscale metal clusters in an inert-gas
atmosphere using constant-energy molecular dynamics. The coalescence proceeds
via atomic diffusion with the release of surface energy raising the
temperature. If the temperature exceeds the melting point of the coalesced
cluster, a molten droplet forms. If the temperature falls between the melting
point of the larger cluster and those of the smaller clusters, a metastable
molten droplet forms and freezes.Comment: 5 figure
KN Scattering and the Nucleon Strangeness Radius
The leading non-zero electric moment of the nucleon strange-quark vector
current is the mean square strangeness radius, , arising from the kaon cloud,
using dispersion relations. Drawing upon unitarity constraints as well as
scattering and cross section data, we find the
structure of this contribution differs significantly from that suggested by a
variety of QCD-inspired model calculations. In particular, we find evidence for
a strong -meson resonance which may enhance the scale of kaon cloud
contribution to an observable level.Comment: 4 pages, RevTex, 1 PS figure, uses epsf.sty, revised to improve
clarity, results unchange
Z^* Resonances: Phenomenology and Models
We explore the phenomenology of, and models for, the Z^* resonances, the
lowest of which is now well established, and called the Theta. We provide an
overview of three models which have been proposed to explain its existence
and/or its small width, and point out other relevant predictions, and potential
problems, for each. The relation to what is known about KN scattering,
including possible resonance signals in other channels, is also discussed.Comment: 29 pages, uses RevTeX4; expanded version (published form
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