2,101 research outputs found
Nonequilibrium Central Limit Theorem for a Tagged Particle in Symmetric Simple Exclusion
We prove a nonequilibirum central limit theorem for the position of a tagged
particle in the one-dimensional nearest-neighbor symmetric simple exclusion
process under diffusive scaling starting from a Bernoulli product measure
associated to a smooth profile \rho_0:\bb R\to [0,1]
Universality of trap models in the ergodic time scale
Consider a sequence of possibly random graphs , ,
whose vertices's have i.i.d. weights with a distribution
belonging to the basin of attraction of an -stable law, .
Let , , be a continuous time simple random walk on which
waits a \emph{mean} exponential time at each vertex . Under
considerably general hypotheses, we prove that in the ergodic time scale this
trap model converges in an appropriate topology to a -process. We apply this
result to a class of graphs which includes the hypercube, the -dimensional
torus, , random -regular graphs and the largest component of
super-critical Erd\"os-R\'enyi random graphs
The role of industry, occupation, and location specific knowledge in the survival of new firms
How do regions acquire the knowledge they need to diversify their economic
activities? How does the migration of workers among firms and industries
contribute to the diffusion of that knowledge? Here we measure the industry,
occupation, and location-specific knowledge carried by workers from one
establishment to the next using a dataset summarizing the individual work
history for an entire country. We study pioneer firms--firms operating in an
industry that was not present in a region--because the success of pioneers is
the basic unit of regional economic diversification. We find that the growth
and survival of pioneers increase significantly when their first hires are
workers with experience in a related industry, and with work experience in the
same location, but not with past experience in a related occupation. We compare
these results with new firms that are not pioneers and find that
industry-specific knowledge is significantly more important for pioneer than
non-pioneer firms. To address endogeneity we use Bartik instruments, which
leverage national fluctuations in the demand for an activity as shocks for
local labor supply. The instrumental variable estimates support the finding
that industry-related knowledge is a predictor of the survival and growth of
pioneer firms. These findings expand our understanding of the micro-mechanisms
underlying regional economic diversification events
Scaling limits of a tagged particle in the exclusion process with variable diffusion coefficient
We prove a law of large numbers and a central limit theorem for a tagged
particle in a symmetric simple exclusion process in the one-dimensional lattice
with variable diffusion coefficient. The scaling limits are obtained from a
similar result for the current through -1/2 for a zero-range process with bond
disorder. For the CLT, we prove convergence to a fractional Brownian motion of
Hurst exponent 1/4.Comment: 9 page
CaracterÃsticas Antropométricas en Atletas de Jiu Jitsu Brasilero de Alto Nivel: Rol del Estilo de Lucha
Indexación: Web of Science; Scielo.SUMMARY: Human performance efficiency and effectiveness in different sports depend to a large extent on the size, weight and proportion of the physique of the athlete. The aim of this study was to identify morphological characteristics of Brazilian Jiu-Jitsu (BJJ) athletes. The sample consisted of 25 highly trained male athletes who were classified according to their fighting style; guard fighter (GF) vs. pass fighter (PF). The athletes were assessed for somatotype, body composition and proportionality. For the whole group of athletes the somatotype was 2.23±0.68, 6.33±1.14, and 1.75±0.87 for endomorph, mesomorph and ectomorph components, respectively. Muscle and adipose tissue percentages were 52.34±2.15% and 19.30±2.51%, respectively. PF were significantly more mesomorph (p< 0.05) and less ectomorph (p< 0.05) than GF. Also, PF had significantly higher phantom Z score for bone mass vs. GF (0.51±0.57 vs. 0.01±0.54; p<0.05), and significantly lower muscle mass- bone mass ratio (4.55±0.31 vs. 4.77±0.56; p<0.05), height (1.71±0.06 vs. 1.77±0.07; p<0.05) and height weight ratio (40.58±1.11 vs. 41.84±1.22). Our results show that morphological characteristics are related to different fighting styles in BJJ athletes.RESUMEN: La eficiencia y efectividad del rendimiento humano en diferentes deportes depende en gran medida del tamaño, peso y proporción del fÃsico del atleta. El objetivo de este estudio fue identificar las caracterÃsticas morfológicas de atletas jiu-jitsu brasileros. La muestra consintió de 25 atletas varones altamente entrenados, quienes fueron clasificados de acuerdo a su estilo de lucha; guarderos (GF) vs pasadores (PF). Se evaluó en los atletas somatotipo, composición corporal y proporcionalidad. Para el grupo total de atletas el somatotipo fue 2,23±0,68, 6,33±1,14 y 1,75±0,78 para el endomorfismo, mesomorfismo y ectomorfismo, respectivamente. Los porcentajes de tejido muscular y adiposo fueron 52,34±2,15% and 19,30±2,51%, respectivamente. PF fueron significativamente las mesomorfos (p<0,05) y menos ectomorfos (p<0,05) que GF. Además PF tuvieron una significativamente alto Z score para la masa ósea (4,55±0,31 vs. 4,77±0,56; p<0,05), estatura (1,71±0,06 vs. 1,77±0,07; p<0,05) y relación altura peso (40,58±1.11 vs. 41,84±1.22). Nuestros resultados muestran que las caracterÃsticas morfológicas están relacionadas a diferentes estilos de lucha en atletas de BJJ.http://ref.scielo.org/bzhxy
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