15,390 research outputs found
Unified model for vortex-string network evolution
We describe and numerically test the velocity-dependent one-scale (VOS)
string evolution model, a simple analytic approach describing a string network
with the averaged correlation length and velocity. We show that it accurately
reproduces the large-scale behaviour (in particular the scaling laws) of
numerical simulations of both Goto-Nambu and field theory string networks. We
explicitly demonstrate the relation between the high-energy physics approach
and the damped and non-relativistic limits which are relevant for condensed
matter physics. We also reproduce experimental results in this context and show
that the vortex-string density is significantly reduced by loop production, an
effect not included in the usual `coarse-grained' approach.Comment: 5 pages; v2: cosmetic changes, version to appear in PR
Probing dark energy beyond with CODEX
Precision measurements of nature's fundamental couplings and a first
measurement of the cosmological redshift drift are two of the key targets for
future high-resolution ultra-stable spectrographs such as CODEX. Being able to
do both gives CODEX a unique advantage, allowing it to probe dynamical dark
energy models (by measuring the behavior of their equation of state) deep in
the matter era and thereby testing classes of models that would otherwise be
difficult to distinguish from the standard CDM paradigm. We illustrate
this point with two simple case studies.Comment: 4 pages, 4 figures; submitted to Phys. Rev.
Kondo regime in triangular arrangements of quantum dots: Molecular orbitals, interference and contact effects
Transport properties of an interacting triple quantum dot system coupled to
three leads in a triangular geometry has been studied in the Kondo regime.
Applying mean-field finite-U slave boson and embedded cluster approximations to
the calculation of transport properties unveils a set of rich features
associated to the high symmetry of this system. Results using both calculation
techniques yield excellent overall agreement and provide additional insights
into the physical behavior of this interesting geometry. In the case when just
two current leads are connected to the three-dot system, interference effects
between degenerate molecular orbitals are found to strongly affect the overall
conductance. An S=1 Kondo effect is also shown to appear for the perfect
equilateral triangle symmetry. The introduction of a third current lead results
in an `amplitude leakage' phenomenon, akin to that appearing in beam splitters,
which alters the interference effects and the overall conductance through the
system.Comment: 14 pages, 9 figures, submitted to PR
AN ALTERNATIVE AND SIMPLE MANNER TO CALCULATE THE THERMAL EFFICIENCY OF COMBUSTION ENGINES
This papers aims to present techniques and methods to develop an alternative equation to determine the thermal efficiency of internal combustion engines. Towards interpolation of data, obtained from thermodynamic tables, it presents a function that allows a faster calculation of efficiency for combustion engines
Sistema de produção agrossilvipastorial para a região de caatinga - SAF: avaliação dos impactos econômicos, sociais e ambientais.
bitstream/CNPC-2010/23041/1/cot110.pd
Exactly Solvable Models of Interacting Spin-s Particles in one-dimension
We consider the exact solution of a many-body problem of spin- particles
interacting through an arbitrary U(1) invariant factorizable -matrix. The
solution is based on a unified formulation of the quantum inverse scattering
method for an arbitrary -dimensional monodromy matrix. The respective
eigenstates are shown to be given in terms of creation fields by a general
new recurrence relation. This allows us to derive the spectrum and the
respective Bethe ansatz equations.Comment: 10 pages, plain late
Análise in silico de proteínas quinases expressas em Coffea arabica.
Apesar da indiscutível importância agronômica do café, particularmente para o Brasil, esta cultura ainda é alvo de diferentes estresses que causam perda em sua produtividade. A resposta do cafeeiro aos diferentes sinais como patógenos e de condições ambientais adversas é ainda desconhecida. Com o objetivo de identificar proteínas quinases, o banco de seqüências expressas de Café (CAFEST) foi investigado. A análise do banco de dados CafEST revelou 479 seqüências identificadas como quinases que formaram um conjunto de 153 unigenes. As proteínas codificadas pelos segmentos expressos correspondem a diferentes e importantes categorias de quinases (MAPK, MAPKK, MAPKKK, receptores, etc). A análise filogenética mostrou a conservação das proteínas expressas no cafeeiro comparado a outras plantas e fungos. Os presentes resultados indicam que a resposta a estresses seja conservada em cafeeiro, provavelmente mediada pelos mecanismos de fosforilação em cascata. Além disso, apontam para o aprofundamento dos estudos destas vias como contribuição aos fenômenos relacionados à interação planta-patógeno
- …