6,342 research outputs found
Interior regularity criteria for suitable weak solutions of the Navier-Stokes equations
We present new interior regularity criteria for suitable weak solutions of
the 3-D Navier-Stokes equations: a suitable weak solution is regular near an
interior point if either the scaled -norm of the velocity
with , , or the -norm of the
vorticity with , , or the
-norm of the gradient of the vorticity with , , , is sufficiently small near
A geometric condition implying energy equality for solutions of 3D Navier-Stokes equation
We prove that every weak solution to the 3D Navier-Stokes equation that
belongs to the class and \n u belongs to localy
away from a 1/2-H\"{o}lder continuous curve in time satisfies the generalized
energy equality. In particular every such solution is suitable.Comment: 10 page
Partial Regularity of solutions to the Four-dimensional Navier-Stokes equations at the first blow-up time
The solutions of incompressible Navier-Stokes equations in four spatial
dimensions are considered. We prove that the two-dimensional Hausdorff measure
of the set of singular points at the first blow-up time is equal to zero.Comment: 19 pages, a comment regarding five or higher dimensional case is
added in Remark 1.3. accepted by Comm. Math. Phy
Independent analysis of the orbits of Pioneer 10 and 11
Independently developed orbit determination software is used to analyze the
orbits of Pioneer 10 and 11 using Doppler data. The analysis takes into account
the gravitational fields of the Sun and planets using the latest JPL
ephemerides, accurate station locations, signal propagation delays (e.g., the
Shapiro delay, atmospheric effects), the spacecrafts' spin, and maneuvers. New
to this analysis is the ability to utilize telemetry data for spin, maneuvers,
and other on-board systematic effects. Using data that was analyzed in prior
JPL studies, the anomalous acceleration of the two spacecraft is confirmed. We
are also able to put limits on any secondary acceleration (i.e., jerk) terms.
The tools that were developed will be used in the upcoming analysis of recently
recovered Pioneer 10 and 11 Doppler data files.Comment: 22 pages, 5 figures; accepted for publication in IJMP
Bacterial adherence and hemolysin production from Escherichia coli induces histamine and leukotriene release from various cells
We investigated the role of bacterial adherence and hemolysin production from Escherichia coli parent and genetically cloned strains as to their eft'ects on bistaJidne release from rat mast cells and leukotriene generation from human polymorphonuclear granulocytes. These mediators were involved in the induction of inftammatory disease processes and led, for example, to enhancement of vascular permeability, chemotaxis (leukotriene 84 [LTB4]), chemoaggregation, lysosomal enzyme release, and smooth muscle contraction, (LTC4, LTD4 , and LTE4). Washed bacteria (E. coli K-12 Ms+ my=; E. coli 536 Ms+ MR= my=) as weil as their culture supematants were analyzed. Washed E. coli K-12 (Hiy+), unlike Hly- strains, induced high amounts of histamine release from rat mast cells and chemotactic activity from human polymorphonuclear granulocytes. Significant leukotriene releasewas obtained with washed E. coli K-12 my+ strains and their bacterial culture supematants. Leukotriene induction was dependent on the amount of hemolysin activity present in the supematant. However, additional soluble factors should also be considered. The presence of hemolysin appeared to aceeierate and enhance the rate of phagocytosis of bacteria by neutrophUs. When E. coli 536 (MS+ MR= Hly=) strains were analyzed, the simultaneous presence of MR+ pili and hemolysin production led to an increase in histamine release as compared with MR- my+ strains. The genetically cloned MR+ my+ E. coli 536 strain induced higher amounts of IeukotrieDes as compared with the wUd-type strain. Our data soggest a potent role for adhesins and hemolysin as virulence factors in inducing the release of inftammatory mediators
On admissibility criteria for weak solutions of the Euler equations
We consider solutions to the Cauchy problem for the incompressible Euler
equations satisfying several additional requirements, like the global and local
energy inequalities. Using some techniques introduced in an earlier paper we
show that, for some bounded compactly supported initial data, none of these
admissibility criteria singles out a unique weak solution.
As a byproduct we show bounded initial data for which admissible solutions to
the p-system of isentropic gas dynamics in Eulerian coordinates are not unique
in more than one space dimension.Comment: 33 pages, 1 figure; v2: 35 pages, corrected typos, clarified proof
Use of real-time quantitative reverse transcription polymerase chain reaction for the detection of African horse sickness virus replication in Culicoides imicola
Despite its important role as vector for African horse sickness virus (AHSV),
very little information is available on the dissemination of this virus in
Culicoides (Avaritia) imicola Kieffer (Diptera: Ceratopogonidae). This study
reports on the applicability of a real-time quantitative reverse transcription
polymerase chain reaction (RT-qPCR) to detect AHSV in dissected midges. A
total of 96 midges were fed on AHSV-infected blood, after which one test group
was dissected into head/thorax and abdomen segments immediately after feeding
and the other only after 10 days of incubation. The majority of the midges
(96%) ingested the virus successfully and there was no significant difference
between the virus concentration in the heads/thoraxes and the abdomens
immediately after feeding. After incubation, virus was detected in 51% of the
midges and it was confined to the abdomen in the majority of these. The fact
that virus was detected only in the heads/thoraxes of four Culicoides midges
after incubation suggests the presence of a mesenteronal escape barrier.
Replication in the salivary glands was not shown. An increase of the mean
virus concentration in the abdomen after incubation indicates localised viral
replication. The real-time RT-qPCR is recommended for further studies
investigating the replication and dissemination of AHSV in Culicoides midges
Hit-and-run algorithms for the indentification of nonredundant linear inequalities
Two probabilistic hit-and-run algorithms are presented to detect nonredundant constraints in a full dimensional system of linear inequalities. The algorithms proceed by generating a random sequence of interior points whose limiting distribution is uniform, and by searching for a nonredundant constraint in the direction of a random vector from each point in the sequence. In the hypersphere directions algorithm tile direction vector is drawn from a uniform distribution on a hypersphere. In tile computalionalb superior coordinate directions algorithm a search is carried out along one of the coordinate vectors. The algorithms are terminated through the use of a Bayesian stopping rule. Computational experience with the algorithms and the stopping rule will be reported
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