2,381 research outputs found
Repulsion of an evolving surface on walls with random heights
We consider the motion of a discrete random surface interacting by exclusion
with a random wall. The heights of the wall at the sites of are i.i.d.\
random variables. Fixed the wall configuration, the dynamics is given by the
serial harness process which is not allowed to go below the wall. We study the
effect of the distribution of the wall heights on the repulsion speed.Comment: 8 page
Two-dimensional Poisson Trees converge to the Brownian web
The Brownian web can be roughly described as a family of coalescing
one-dimensional Brownian motions starting at all times in and at all
points of . It was introduced by Arratia; a variant was then studied by
Toth and Werner; another variant was analyzed recently by Fontes, Isopi, Newman
and Ravishankar. The two-dimensional \emph{Poisson tree} is a family of
continuous time one-dimensional random walks with uniform jumps in a bounded
interval. The walks start at the space-time points of a homogeneous Poisson
process in and are in fact constructed as a function of the point
process. This tree was introduced by Ferrari, Landim and Thorisson. By
verifying criteria derived by Fontes, Isopi, Newman and Ravishankar, we show
that, when properly rescaled, and under the topology introduced by those
authors, Poisson trees converge weakly to the Brownian web.Comment: 22 pages, 1 figure. This version corrects an error in the previous
proof. The results are the sam
A line-binned treatment of opacities for the spectra and light curves from neutron star mergers
The electromagnetic observations of GW170817 were able to dramatically
increase our understanding of neutron star mergers beyond what we learned from
gravitational waves alone. These observations provided insight on all aspects
of the merger from the nature of the gamma-ray burst to the characteristics of
the ejected material. The ejecta of neutron star mergers are expected to
produce such electromagnetic transients, called kilonovae or macronovae.
Characteristics of the ejecta include large velocity gradients, relative to
supernovae, and the presence of heavy -process elements, which pose
significant challenges to the accurate calculation of radiative opacities and
radiation transport. For example, these opacities include a dense forest of
bound-bound features arising from near-neutral lanthanide and actinide
elements. Here we investigate the use of fine-structure, line-binned opacities
that preserve the integral of the opacity over frequency. Advantages of this
area-preserving approach over the traditional expansion-opacity formalism
include the ability to pre-calculate opacity tables that are independent of the
type of hydrodynamic expansion and that eliminate the computational expense of
calculating opacities within radiation-transport simulations. Tabular opacities
are generated for all 14 lanthanides as well as a representative actinide
element, uranium. We demonstrate that spectral simulations produced with the
line-binned opacities agree well with results produced with the more accurate
continuous Monte Carlo Sobolev approach, as well as with the commonly used
expansion-opacity formalism. Additional investigations illustrate the
convergence of opacity with respect to the number of included lines, and
elucidate sensitivities to different atomic physics approximations, such as
fully and semi-relativistic approaches.Comment: 27 pages, 22 figures. arXiv admin note: text overlap with
arXiv:1702.0299
Analytical results for a Bessel function times Legendre polynomials class integrals
When treating problems of vector diffraction in electromagnetic theory, the
evaluation of the integral involving Bessel and associated Legendre functions
is necessary. Here we present the analytical result for this integral that will
make unnecessary numerical quadrature techniques or localized approximations.
The solution is presented using the properties of the Bessel and associated
Legendre functions.Comment: 4 page
Modificação da composição florÃstica da comunidade de plantas daninhas em guaranazal submetido à correção da fertilidade do solo.
O objetivo deste trabalho foi caracterizar alterações na composição especÃfica de plantas daninhas em um guaranazal submetido à gessagem
Stability of a lyophilized milk enriched with microbial CLA/CLNA
Conjugated linoleic (CLA) and conjugated linolenic (CLNA) acids have been described with potential bioactive properties. Due limited availability in their natural sources (e.g. ruminants’ milk and meat or vegetable oils), in situ microbial production in dairy products may potentially improve CLA/CLNA daily intake. Several probiotic strains have been reported to produce CLA/CLNA isomers using linoleic (LA) and alpha-linolenic (α-LNA) acids as precursor substrates, respectively. Previous work by this research team led to the formulation of a CLA/CLNA-enriched lyophilized milk, using Bifidobacterium breve DSM 20091 and hydrolysed flaxseed oil (FSO; rich in α-LNA). Since CLA, CLNA, LA and α-LNA are polyunsaturated and prone to oxidation, this research aimed to investigate if this new functional milk product is stable at conditions mimicking shelf-life. Pasteurized cow milk (100 mL) inoculated with B. breve DSM 20091 and hydrolysed FSO or not (control) was fermented for 22 h at 37 ºC under anaerobic conditions. Afterwards, samples were lyophilized and stored at room temperature in an exicator, being air- and light-protected. Samples were taken at the beginning (T0wk) and every 4 weeks until the end of the assay (T12wk) for further microbial counting and fatty acid (FA) analysis. Concerning to B. breve DSM 20091 viable cell counting, counts remained below the countable range during the entire study, so as total microbial counting. As for FA analysis, in the non-esterified fraction, the CLA and CLNA contents in the enriched milk product increased after 4 weeks (up to 1.80 and 11.12 mg/g, respectively) and, thereafter, no significant differences were detected. The same was observed for total polyunsaturated FA, but, in the esterified fraction, its level increased significantly after 8 weeks (up to 6.01 mg/g) and then reduced to 5.18 mg/g at the end of the study. In conclusion, a lyophilised milk enriched with microbial CLA/CLNA is not entirely stable, including its CLA/CLNA content, which was inclusively enhanced.info:eu-repo/semantics/publishedVersio
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