2,550 research outputs found
Tailoring restoration interventions to the grassland-savanna-forest complex in central Brazil
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Basketball game-related statistics that discriminate between teams season-long success
The aim of the present study was to identify the game-related statistics that discriminate between season-long successful and unsuccessful basketball teams participating in the Spanish Basketball League (LEB1). The sample included all 145 average records per season from the 870 games played between the 2000-2001 and the 2005-2006 regular seasons. The following game-related statistics were gathered from the official box scores of the Spanish Basketball Federation: 2- and 3-point field-goal attempts (both successful and unsuccessful), free-throws (both successful and unsuccessful), defensive and offensive rebounds, assists, steals, turnovers, blocks (both made and received), and fouls (both committed and received). To control for season variability, all results were normalized to minutes played each season and then converted to z-scores. The results allowed discrimination between best and worst teams' performances through the following game-related statistics: assists (SC=0.47), steals (SC=0.34), and blocks (SC=0.30). The function obtained correctly classified 82.4% of the cases. In conclusion, season-long performance may be supported by players' and teams' passing skills and defensive preparation
Symmetries and Ambiguities in the linear sigma model with light quarks
We investigate the role of undetermined finite contributions generated by
radiative corrections in a linear sigma model with quarks.
Although some of such terms can be absorbed in the renormalization procedure,
one such contribution is left in the expression for the pion decay constant.
This arbitrariness is eliminated by chiral symmetry.Comment: 9 pages. Added references through the text; an author was added due
to an important contribution; corrected typos; the title also was changed.
Submitted to Modern Physics Letter
Ultraviolet and Infrared Divergences in Implicit Regularization: a Consistent Approach
Implicit Regularization is a 4-dimensional regularization initially conceived
to treat ultraviolet divergences. It has been successfully tested in several
instances in the literature, more specifically in those where Dimensional
Regularization does not apply. In the present contribution we extend the method
to handle infrared divergences as well. We show that the essential steps which
rendered Implicit Regularization adequate in the case of ultraviolet
divergences have their counterpart for infrared ones. Moreover we show that a
new scale appears, typically an infrared scale which is completely independent
of the ultraviolet one. Examples are given.Comment: 9 pages, version to appear in Mod. Phys. Lett.
Tropical dry-forest regeneration from root suckers in Central Brazil.
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Previous issue date: 2007-01-0
Determinação da relação solo planta em pomar de citros com diferentes combinações copa/porta-enxerto.
A importância socioeconômica da citricultura no Nordeste brasileiro é incontestável. No entanto, problemas como a distribuição irregular de chuva na região onde se localizam os pomares - concentrada em seis a oito meses do ano - interferem de forma direta no crescimento e desenvolvimento das plantas. Em função disso, a busca de genótipos tolerantes a deficiência hídrica é crucial para a permanência da citricultura nesse território
Entanglement and scattering in quantum electrodynamics: S-matrix information from an entangled spectator particle
We consider a general quantum field relativistic scattering involving two
half spin fermions, and , which are initially entangled with another
fermion that does not participate in the scattering dynamics. We construct
general expressions for the reduced spin matrices for the out-state considering
a general tripartite spin-entangled state. In particular we study an inelastic
QED process at tree-level, namely and a half
spin fermion as an spectator particle which can be entangled to the
system in the following ways: W state, GHZ state, and , where are the Bell basis states and is a spin
superposition state of system . We calculate the von-Neumann entropy
variation before and after the scattering for the particle and show that
spin measurements in contain numerical information about the total cross
section of the process. We compare the initial states W and GHZ as well as
study the role played by the parameter in the evaluation of the
entropy variations and the cross section encoded in the spectator particle.Comment: 12 pages, 10 figure
Scalar Casimir Effect on a D-dimensional Einstein Static Universe
We compute the renormalised energy momentum tensor of a free scalar field
coupled to gravity on an (n+1)-dimensional Einstein Static Universe (ESU),
RxS^n, with arbitrary low energy effective operators (up to mass dimension
n+1). A generic class of regulators is used, together with the Abel-Plana
formula, leading to a manifestly regulator independent result. The general
structure of the divergences is analysed to show that all the gravitational
couplings (not just the cosmological constant) are renormalised for an
arbitrary regulator. Various commonly used methods (damping function,
point-splitting, momentum cut-off and zeta function) are shown to, effectively,
belong to the given class. The final results depend strongly on the parity of
n. A detailed analytical and numerical analysis is performed for the behaviours
of the renormalised energy density and a quantity `sigma' which determines if
the strong energy condition holds for the `quantum fluid'. We briefly discuss
the quantum fluid back-reaction problem, via the higher dimensional Friedmann
and Raychaudhuri equations, observe that equilibrium radii exist and unveil the
possibility of a `Casimir stabilisation of Einstein Static Universes'.Comment: 37 pages, 15 figures, v2: minor changes in sections 1, 2.5, 3 and 4;
version published in CQ
Two-loop renormalisation of gauge theories in Implicit Regularisation: transition rules to dimensional methods
We compute the two-loop -function of scalar and spinorial quantum
electrodynamics as well as pure Yang-Mills and quantum chromodynamics using the
background field method in a fully quadridimensional setup using Implicit
Regularization (IREG). Moreover, a thorough comparison with dimensional
approaches such as conventional dimensional regularization (CDR) and
dimensional reduction (DRED) is presented. Particularly, for our calculations
we show that the inclusion of evanescent -scalar particle
contributions needed in quasi-dimensional methods such as DRED and Four
Dimensional Helicity (FDH) cancel out in the determination of the ultraviolet
(UV) structure of the models we study. Subtleties related to Lorentz algebra
contractions/symmetric integrations inside divergent integrals as well as
renormalisation schemes are carefully discussed within IREG where the
renormalisation constants are fully defined as basic divergent integrals to
arbitrary loop order. Moreover we confirm the hypothesis that momentum routing
invariance in the loops of Feynman diagramas implemented via setting
well-defined surface terms to zero deliver non-abelian gauge invariant
amplitudes within IREG just as it has been proven for abelian theories
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