12,251 research outputs found
On the unsteady behavior of turbulence models
Periodically forced turbulence is used as a test case to evaluate the
predictions of two-equation and multiple-scale turbulence models in unsteady
flows. The limitations of the two-equation model are shown to originate in the
basic assumption of spectral equilibrium. A multiple-scale model based on a
picture of stepwise energy cascade overcomes some of these limitations, but the
absence of nonlocal interactions proves to lead to poor predictions of the time
variation of the dissipation rate. A new multiple-scale model that includes
nonlocal interactions is proposed and shown to reproduce the main features of
the frequency response correctly
Persistence of the valence bond glass state in the double perovskites Ba2-xSrxYMoO6
Peer reviewedPublisher PD
Sclera solar diameter observations
Focus is given to possible variations in solar luminosity and accurate methods of monitoring it. Aside from direct bolometry, one methodology for this type of research makes use of measurements of the solar diameter and limb darkening function as indirect indicators of the solar luminosity. This approach was reviewed
Irrigation and drainage performance assessment: practical guidelines
Irrigation management / Drainage / Performance evaluation / Performance indexes / Evapotranspiration / Precipitation / Water balance / Participatory rural appraisal / Databases / Simulation
Geometric quantization of Hamiltonian actions of Lie algebroids and Lie groupoids
We construct Hermitian representations of Lie algebroids and associated
unitary representations of Lie groupoids by a geometric quantization procedure.
For this purpose we introduce a new notion of Hamiltonian Lie algebroid
actions. The first step of our procedure consists of the construction of a
prequantization line bundle. Next, we discuss a version of K\"{a}hler
quantization suitable for this setting. We proceed by defining a
Marsden-Weinstein quotient for our setting and prove a ``quantization commutes
with reduction'' theorem. We explain how our geometric quantization procedure
relates to a possible orbit method for Lie groupoids. Our theory encompasses
the geometric quantization of symplectic manifolds, Hamiltonian Lie algebra
actions, actions of families of Lie groups, foliations, as well as some general
constructions from differential geometry.Comment: 40 pages, corrected version 11-01-200
Diagnostic, Prognostic, and Therapeutic Implications of Genetic Testing for Hypertrophic Cardiomyopathy
Over the last 2 decades, the pathogenic basis for the most common heritable cardiovascular disease, hypertrophic cardiomyopathy (HCM), has been investigated extensively. Affecting approximately 1 in 500 individuals, HCM is the most common cause of sudden death in young athletes. In recent years, genomic medicine has been moving from the bench to the bedside throughout all medical disciplines including cardiology. Now, genomic medicine has entered clinical practice as it pertains to the evaluation and management of patients with HCM. The continuous research and discoveries of new HCM susceptibility genes, the growing amount of data from genotype-phenotype correlation studies, and the introduction of commercially available genetic tests for HCM make it essential that the modern-day cardiologist understand the diagnostic, prognostic, and therapeutic implications of HCM genetic testing
Valence bond glass on an fcc lattice in the double perovskite Ba2YMoO6
Peer reviewedPublisher PD
Octet Baryon Magnetic Moments in the Chiral Quark Model with Configuration Mixing
The Coleman-Glashow sum-rule for magnetic moments is always fulfilled in the
chiral quark model, independently of SU(3) symmetry breaking. This is due to
the structure of the wave functions, coming from the non-relativistic quark
model. Experimentally, the Coleman-Glashow sum-rule is violated by about ten
standard deviations. To overcome this problem, two models of wave functions
with configuration mixing are studied. One of these models violates the
Coleman-Glashow sum-rule to the right degree and also reproduces the octet
baryon magnetic moments rather accurately.Comment: 22 pages, RevTe
Inertial range scaling of the scalar flux spectrum in two-dimensional turbulence
Two-dimensional statistically stationary isotropic turbulence with an imposed
uniform scalar gradient is investigated. Dimensional arguments are presented to
predict the inertial range scaling of the turbulent scalar flux spectrum in
both the inverse cascade range and the enstrophy cascade range for small and
unity Schmidt numbers. The scaling predictions are checked by direct numerical
simulations and good agreement is observed
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