20,850 research outputs found
Instantons and Chern-Simons flows in 6, 7 and 8 dimensions
The existence of K-instantons on a cylinder M^7 = R_tau x K/H over a
homogeneous nearly K"ahler 6-manifold K/H requires a conformally parallel or a
cocalibrated G_2-structure on M^7. The generalized anti-self-duality on M^7
implies a Chern-Simons flow on K/H which runs between instantons on the coset.
For K-equivariant connections, the torsionful Yang-Mills equation reduces to a
particular quartic dynamics for a Newtonian particle on C. When the torsion
corresponds to one of the G_2-structures, this dynamics follows from a gradient
or hamiltonian flow equation, respectively. We present the analytic (kink-type)
solutions and plot numerical non-BPS solutions for general torsion values
interpolating between the instantonic ones.Comment: 1+8 pages, 14 figures; talk presented at SQS-11 during 18-23 July,
2011, at JINR, Dubna, Russia; v2: missing * in eq.(1) adde
SLE-type growth processes and the Yang-Lee singularity
The recently introduced SLE growth processes are based on conformal maps from
an open and simply-connected subset of the upper half-plane to the half-plane
itself. We generalize this by considering a hierarchy of stochastic evolutions
mapping open and simply-connected subsets of smaller and smaller fractions of
the upper half-plane to these fractions themselves. The evolutions are all
driven by one-dimensional Brownian motion. Ordinary SLE appears at grade one in
the hierarchy. At grade two we find a direct correspondence to conformal field
theory through the explicit construction of a level-four null vector in a
highest-weight module of the Virasoro algebra. This conformal field theory has
central charge c=-22/5 and is associated to the Yang-Lee singularity. Our
construction may thus offer a novel description of this statistical model.Comment: 12 pages, LaTeX, v2: thorough revision with corrections, v3: version
to be publishe
Runtime Verification of Temporal Properties over Out-of-order Data Streams
We present a monitoring approach for verifying systems at runtime. Our
approach targets systems whose components communicate with the monitors over
unreliable channels, where messages can be delayed or lost. In contrast to
prior works, whose property specification languages are limited to
propositional temporal logics, our approach handles an extension of the
real-time logic MTL with freeze quantifiers for reasoning about data values. We
present its underlying theory based on a new three-valued semantics that is
well suited to soundly and completely reason online about event streams in the
presence of message delay or loss. We also evaluate our approach
experimentally. Our prototype implementation processes hundreds of events per
second in settings where messages are received out of order.Comment: long version of the CAV 2017 pape
Glossinidae
One zebu bull of 365 kg live weight was treated along the back line with 36 mL
of fipronil as a pour-on formulation. Long-lasting mortalities of Glossina
palpalis gambiensis were recorded despite exposure to sunlight and regular
rinsing with 50 L of water during the following 5 months. Significantly higher
mortalities were still observed even 140, 170 and 190 days after treatment
following their triple releases or triple feeding of caged tsetse on the
treated bull. Mortalities of 70, 80 and 44 %, respectively, were recorded
after 15 days of observation. This contrasted with the mortalities of control
flies that were released in the presence of the untreated bull or fed in cages
on the animal, amounting to 20 and twice 10 % after 170 and 190 days. The
feeding successes of the released or caged flies were higher than 95 % and did
not differ between control and experimental groups, indicating no repulsive or
irritant effects of fipronil. The findings of this study are discussed,
particularly in view of the potential of fipronil as an effective means for
tsetse control
ICONGETM v1.0 – flexible NUOPC-driven two-way coupling via ESMF exchange grids between the unstructured-grid atmosphere model ICON and the structured-grid coastal ocean model GETM
Two-way model coupling is important for representing the mutual interactions and feedbacks between atmosphere and ocean dynamics. This work presents the development of the two-way coupled model system ICONGETM, consisting of the atmosphere model ICON and the ocean model GETM. ICONGETM is built on the latest NUOPC coupling software with flexible data exchange and conservative interpolation via ESMF exchange grids. With ICON providing a state-of-the-art kernel for numerical weather prediction on an unstructured mesh and GETM being an established coastal ocean model, ICONGETM is especially suited for high-resolution studies. For demonstration purposes the newly developed model system has been applied to a coastal upwelling scenario in the central Baltic Sea
Temperature dependence of surface stress across an order-disorder transition: p(1x2)O/W(110)
Strain relaxations of a p(1x2) ordered oxygen layer on W(110) are measured as
a function of temperature across the disordering transition using low-energy
electron diffraction. The measured strains approach values of 0.027 in the
[1-10] and -0.053 in the [001] direction. On the basis of the measured strain
relaxations, we give quantitative information on temperature-dependent surface
stress using the results of ab initio calculations. From the surface formation
energy for different strains, determined by first-principles calculations, we
estimate that surface stress changes from -1.1 for the ordered phase to -0.2N/m
for the disordered one along [1-10], and from 5.1 to 3.4 N/m along [001].
Moreover, our observation that the strains scale inversely with domain size
confirms that the strain relaxation takes place at the domain boundaries.Comment: 8 pages, 5 figure
Exactly solvable model with two conductor-insulator transitions driven by impurities
We present an exact analysis of two conductor-insulator transitions in the
random graph model. The average connectivity is related to the concentration of
impurities. The adjacency matrix of a large random graph is used as a hopping
Hamiltonian. Its spectrum has a delta peak at zero energy. Our analysis is
based on an explicit expression for the height of this peak, and a detailed
description of the localized eigenvectors and of their contribution to the
peak. Starting from the low connectivity (high impurity density) regime, one
encounters an insulator-conductor transition for average connectivity
1.421529... and a conductor-insulator transition for average connectivity
3.154985.... We explain the spectral singularity at average connectivity
e=2.718281... and relate it to another enumerative problem in random graph
theory, the minimal vertex cover problem.Comment: 4 pages revtex, 2 fig.eps [v2: new title, changed intro, reorganized
text
High prevalence of vitamin D insufficiency in professional handball athletes
OBJECTIVES: Vitamin D affects multiple body functions through the regulation of gene expression. In sports medicine, its influence on musculoskeletal health and performance is of particular interest. Vitamin D insufficiency might decrease athletic performance and increase the risk of musculoskeletal injuries. Several studies have demonstrated vitamin D deficiency in professional athletes; however, the prevalence of vitamin D insufficiency in professional handball players is yet unknown.
METHODS: The study was planned as a prospective, non-interventional study. We examined 70 male elite handball athletes (first league) in a pre-competition medical assessment in July. Age, height, weight, body mass index, 25-OH vitamin D, calcium, and parathyroid hormone were evaluated, and a sun exposure score was calculated. Players were then divided into two groups of vitamin D levels: insufficient (<30 ng/mL) and sufficient (≥30 ng/mL).
RESULTS: The mean 25-OH vitamin D level of the 70 players was 33.5 ± 10.9 ng/mL (median 32.2, IQR 26.5-38.9 ng/mL). Thirty-nine (55.7%) had sufficient and 31 (44.3%) insufficient levels. Athletes with sufficient vitamin D levels had significantly lower parathyroid hormone levels than athletes with insufficiency (24.9 ± 12.1 vs. 33.5 ± 15.1 ng/mL, p = 0.02). All other parameters evaluated demonstrated no significant difference between the two groups.
CONCLUSION: Vitamin D insufficiency is a common finding in professional handball athletes even in summer, which might negatively affect physical performance. Furthermore, it might lead to an increased risk of musculoskeletal injuries and infections. This should be evaluated in further studies
Critical curves in conformally invariant statistical systems
We consider critical curves -- conformally invariant curves that appear at
critical points of two-dimensional statistical mechanical systems. We show how
to describe these curves in terms of the Coulomb gas formalism of conformal
field theory (CFT). We also provide links between this description and the
stochastic (Schramm-) Loewner evolution (SLE). The connection appears in the
long-time limit of stochastic evolution of various SLE observables related to
CFT primary fields. We show how the multifractal spectrum of harmonic measure
and other fractal characteristics of critical curves can be obtained.Comment: Published versio
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