601 research outputs found
On the structure and spectrum of classical two-dimensional clusters with a logarithmic interaction potential
We present a numerical study of the effect of the repulsive logarithmic
inter-particle interaction on the ground state configuration and the frequency
spectrum of a confined classical two-dimensional cluster containing a finite
number of particles. In the case of a hard wall confinement all particles form
one ring situated at the boundary of the potential. For a general r^n
confinement potential, also inner rings can form and we find that all
frequencies lie below the frequency of a particular mode, namely the
breathing-like mode. An interesting situation arises for the parabolic confined
system(i.e. n=2). In this case the frequency of the breathing mode is
independent of the number of particles leading to an upper bound for all
frequencies. All results can be understood from Earnshaw's theorem in two
dimensions. In order to check the sensitivity of these results, the spectrum of
vortices in a type II superconductor which, in the limit of large penetration
depths, interact through a logarithmic potential, is investigated.Comment: 11 pages, 6 figure
An Algebraic q-Deformed Form for Shape-Invariant Systems
A quantum deformed theory applicable to all shape-invariant bound-state
systems is introduced by defining q-deformed ladder operators. We show these
new ladder operators satisfy new q-deformed commutation relations. In this
context we construct an alternative q-deformed model that preserve the
shape-invariance property presented by primary system. q-deformed
generalizations of Morse, Scarf, and Coulomb potentials are given as examples
Macroscopic 2D Wigner islands
In this paper we present new versatile "2D macroscopic Wigner islands" useful
to investigate the various behaviors observed in mesoscopic confined systems.
Our "Wigner islands" consist of electrostatically-interacting charged balls
with millimetric size. We have experimentally determined the ground
configurations for systems of N particles (N=1-30) confined in a parabolic
potential and checked the influence of the confinement and interacting
potentials. The results obtained are compared with the published numerical
results.Comment: 8 pages, 4 figure
Perfectly Translating Lattices on a Cylinder
We perform molecular dynamics simulations on an interacting electron gas
confined to a cylindrical surface and subject to a radial magnetic field and
the field of the positive background. In order to study the system at lowest
energy states that still carry a current, initial configurations are obtained
by a special quenching procedure. We observe the formation of a steady state in
which the entire electron-lattice cycles with a common uniform velocity.
Certain runs show an intermediate instability leading to lattice
rearrangements. A Hall resistance can be defined and depends linearly on the
magnetic field with an anomalous coefficient reflecting the manybody
contributions peculiar to two dimensions.Comment: 13 pages, 5 figure
The role of clothing in thermal comfort: how people dress in a temperate and humid climate in Brazil
Abstract Thermal insulation from clothing is one of the most important input variables used to predict the thermal comfort of a building's occupants. This paper investigates the clothing pattern in buildings with different configurations located in a temperate and humid climate in Brazil. Occupants of two kinds of buildings (three offices and two university classrooms) assessed their thermal environment through 'right-here-right-now' questionnaires, while at the same time indoor climatic measurements were carried out in situ (air temperature and radiant temperature, air speed and humidity). A total of 5,036 votes from 1,161 occupants were collected. Results suggest that the clothing values adopted by occupants inside buildings were influenced by: 1) climate and seasons of the year; 2) different configurations and indoor thermal conditions; and 3) occupants' age and gender. Significant intergenerational and gender differences were found, which might be explained by differences in metabolic rates and fashion. The results also indicate that there is a great opportunity to exceed the clothing interval of the thermal comfort zones proposed by international standards such as ASHRAE 55 (2013) - 0.5 to 1.0 clo - and thereby save energy from cooling and heating systems, without compromising the occupants' indoor thermal comfort
Validação do IAF estimado a partir do coeficiente de extinção da radiação PAR.
Nesse estudo foram realizados experimentos de campo durante as safras sojĂcolas 2017/2018 e 2018/2019, na Faculdade Marechal Rondon (FARON) em Vilhena-RO, para mensurar o IAF da cultivar 75I77 RSF IPRO a partir da estimativa do coeficiente de extinção da radiação fotossinteticamente ativa (PAR).CBAGRO 2023
Variabilidade e parâmetros genéticos para caracteres relacionados à produção de sementes em cruzamentos de Brachiaria spp.
Determinar a variabilidade e estimar os parâmetros genĂ©ticos entre caracteres relacionados ao potencial de produção de sementes Ă© uma das etapas principais em programa de melhoramento genĂ©tico, visto que frequentemente esse gĂŞnero apresenta peculiaridades reprodutivas, tornando, assim, um desafio a produção comercial de sementes. O objetivo desse trabalho foi estimar parâmetros genĂ©ticos para variáveis relacionadas a produção de sementes em genĂłtipos resultantes dos cruzamentos entre genitores sexuais de B. decumbens e apomĂticos de B. brizantha
Recent advances in the understanding and management of polycystic ovary syndrome [version 1; peer review: 3 approved]
Polycystic ovary syndrome (PCOS) is a multifaceted condition characterized by chronic anovulation and excess ovarian activity, in contrast to other causes of anovulation that involve ovarian dormancy or primary insufficiency. Recent studies indicated that PCOS is associated with low-grade chronic inflammation and that women with PCOS are at increased risk of non-alcoholic fatty liver disease. The inflammatory and metabolic derangements associated with PCOS are explained in part by the coexistence of insulin resistance and obesity but are further fueled by the androgen excess. New insights into the regulation of hormones and cytokines in muscle and fat tissue support the concept that PCOS is a systemic syndrome. The therapeutic plan should be tailored to the patient phenotype, complaints, and reproductive desire. Of note, the aromatase inhibitor letrozole seems to be more effective than the reference drug clomiphene citrate to treat infertility due to PCOS. Integral management by a multidisciplinary team may help the patients to adhere to lifestyle interventions and thereby reduce body adiposity and recover their metabolic and reproductive health
- …