17,866 research outputs found
Analytical BPS Maxwell-Higgs vortices
We have established a prescription for the calculation of analytical vortex
solutions in the context of generalized Maxwell-Higgs models whose overall
dynamics is controlled by two positive functions of the scalar field. We have
also determined a natural constraint between these functions and the Higgs
potential allowing the existence of axially symmetric
Bogomol'nyi-Prasad-Sommerfield (BPS) solutions possessing finite energy.
Furthermore, when the generalizing functions are chosen suitably, the
nonstandard BPS equations can be solved exactly. We have studied some examples,
comparing them with the usual Abrikosov-Nielsen-Olesen (ANO) solution. The
overall conclusion is that the analytical self-dual vortices are well-behaved
in all relevant sectors, strongly supporting the generalized models they belong
themselves. In particular, our results mimic well-known properties of the usual
(numerical) configurations, as localized energy density, while contributing to
the understanding of topological solitons and their description by means of
analytical methods.Comment: 8 pages, 4 figure
Coherent State Path Integrals in the Weyl Representation
We construct a representation of the coherent state path integral using the
Weyl symbol of the Hamiltonian operator. This representation is very different
from the usual path integral forms suggested by Klauder and Skagerstan in
\cite{Klau85}, which involve the normal or the antinormal ordering of the
Hamiltonian. These different representations, although equivalent quantum
mechanically, lead to different semiclassical limits. We show that the
semiclassical limit of the coherent state propagator in Weyl representation is
involves classical trajectories that are independent on the coherent states
width. This propagator is also free from the phase corrections found in
\cite{Bar01} for the two Klauder forms and provides an explicit connection
between the Wigner and the Husimi representations of the evolution operator.Comment: 23 page
Dynamical evolution of V-type asteroids in the central main belt
V-type asteroids are associated with basaltic composition, and are supposed
to be fragments of crust of differentiated objects. Most V-type asteroids in
the main belt are found in the inner main belt, and are either current members
of the Vesta dynamical family (Vestoids), or past members that drifted away.
However, several V-type photometric candidates have been recently identified in
the central and outer main belt.
The origin of this large population of V-type objects is not well understood.
Since it seems unlikely that Vestoids crossing the 3J:-1A mean-motion resonance
with Jupiter could account for the whole population of V-type asteroids in the
central and outer main belt, origin from local sources, such as the parent
bodies of the Eunomia, and of the Merxia and Agnia asteroid families, has been
proposed as an alternative mechanism.
In this work we investigated the dynamical evolution of the V-type
photometric candidates in the central main belt, under the effect of
gravitational and non-gravitational forces. Our results show that dynamical
evolution from the parent bodies of the Eunomia and Merxia/Agnia families on
timescales of 2 Byr or more could be responsible for the current orbital
location of most of the low-inclined V-type asteroids.Comment: 16 pages, 10 figures, 3 tables. Accepted for publication in MNRA
Dynamical evolution and chronology of the Hygiea asteroid family
The asteroid (10) Hygiea is the fourth largest asteroid of the Main Belt, by
volume and mass, and it is the largest member of its own family. Previous works
investigated the long-term effects of close encounters with (10) Hygiea of
asteroids in the orbital region of the family, and analyzed the taxonomical and
dynamical properties of members of this family. In this paper we apply the
high-quality SDSS-MOC4 taxonomic scheme of DeMeo and Carry (2013) to members of
the Hygiea family core and halo, we obtain an estimate of the minimum time and
number of encounter necessary to obtain a (or 99.7%) compatible
frequency distribution function of changes in proper caused by close
encounters with (10) Hygiea, we study the behavior of asteroids near secular
resonance configurations, in the presence and absence of the Yarkovsky force,
and obtain a first estimate of the age of the family based on orbital diffusion
by the Yarkovsky and YORP effects with two methods.
The Hygiea family is at least 2 Byr old, with an estimated age of Myr and a relatively large initial ejection velocity field,
according to the approach of Vokrouhlick\'{y} et al. (2006a, b). Surprisingly,
we found that the family age can be shortened by 25% if the dynamical
mobility caused by close encounters with (10) Hygiea is also accounted for,
which opens interesting new research lines for the dynamical evolution of
families associated with massive bodies. In our taxonomical analysis of the
Hygiea asteroid family, we also identified a new V-type candidate: the asteroid
(177904) (2005 SV5). If confirmed, this could be the fourth V-type object ever
to be identified in the outer main belt.Comment: 13 page, 15 figures, and 4 table
Estudo de raízes de coqueiro anão verde em neossolos quartzarênicos da Fazenda São João, em Petrolina-PE.
O estudo foi desenvolvido em Neossolo Quartzarênico, que tem 96% de areia, 2% de silte e 2% de argila em área de plantio comercial da Fazenda São João, município de Petrolina - PE; cultivada com coqueiro anão ecotipo verde, com idade de 7 anos; plantado no espaçamento quiconcial de 7,5 x 7,5 x 7,5 metros, irrigado por microaspersão. Para irrigação utilizou-se um emissor por planta que disponibiliza uma vazão média de 40 L/h, para uma pressão de 204,00 kPa, com uma percentagem de área molhada de 48,70%. Duas plantas foram escolhidas como representativas da área para análise de distribuição de raízes no solo. Os resultados obtidos permitem estabelecer, que até a distância de 2,40 m do caule, estão concentrados 98,17% da área acumulada das raízes. No que se refere à profundidade e até a distância de 2,40 m, menos de 6% das raízes estão abaixo de 1,20 m. As raízes mais compridas e as de maior área estão localizadas entre 0,20 e 0,60 m de profundidade numa sequência crscente até a distância de 1,80 m
Determinações biométricas e avaliação de variáveis relacionadas à germinação de sementes de timborana (Piptadenia suaveolens Miq.).
Atividade de pep-carboxilase e da glutamina sintetase em genótipos de milho e sorgo contrastantes em eficiência de uso de nitrogênio.
A selecao para aumento da eficiencia de uso do N (EUN) foi feita no campo, mas para as determinacoes das atividades da fosfoenolpiruvato carboxilase (PEP-case) e da glutamina sintetase (GS), duas linhagens de milho (Zea mays L.) e duas cvs de sorgo (Sorghum bicolor (L.) Moench), contrastantes em EUN, foram cultivadas em vermiculita por 21 e 35 dias respectivamente, quando a 4a folha de cada planta foi colhida para analise. A atividade biossintetica da GS foi determinada em uma reacao acoplada com a piruvato quinase e a lactato desidrogenase, enquanto a atividade da PES-case foi determinada pela reducao do oxaloacetato a malato, em presenca da malato desidrogenase e NADH. Nos dois ensaios monitorou-se a oxidacao do NADH em 340 nm. Os resultados indicam, no nivel de 1.6 mM de NO3-, que as atividades da GS nao foram diferentes entre os genotipos de milho e sorgo contrastantes em EUN. No nivel de 16 mM de No3- entretanto, os genotipos de milho e sorgo com maior EUN mostraram maior atividade da GS que os genotipos menos eficientes. A cv eficiente de sorgo 8701016 mostrou maiores atividades da PEP-case que a menos eficiente 9109065, nos dois niveis de nitrato utilizados nesse experimento
Parasitismo gastrintestinal de ovinos SRD em diferentes ofertas de biomassa de capim-buffel no Semiárido pernambucano.
Zootec 2011
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