13,617 research outputs found
On the tensor convolution and the quantum separability problem
We consider the problem of separability: decide whether a Hermitian operator
on a finite dimensional Hilbert tensor product is separable or entangled. We
show that the tensor convolution defined for certain mappings on an almost
arbitrary locally compact abelian group, give rise to formulation of an
equivalent problem to the separability one.Comment: 13 pages, two sections adde
A New Test of the Einstein Equivalence Principle and the Isotropy of Space
Recent research has established that nonsymmetric gravitation theories like
Moffat's NGT predict that a gravitational field singles out an orthogonal pair
of polarization states of light that propagate with different phase velocities.
We show that a much wider class of nonmetric theories encompassed by the formalism predict such violations of the Einstein equivalence principle.
This gravity-induced birefringence of space implies that propagation through a
gravitational field can alter the polarization of light. We use data from
polarization measurements of extragalactic sources to constrain birefringence
induced by the field of the Galaxy. Our new constraint is times sharper
than previous ones.Comment: 21 pages, Latex, 3 Postscript figure
Extreme-Point-based Heuristics for the Three-Dimensional Bin Packing problem
One of the main issues in addressing three-dimensional packing problems is finding an efficient and accurate definition of the points at which to place the items inside the bins, because the performance of exact and heuristic solution methods is actually strongly influenced by the choice of a placement rule. We introduce the extreme point concept and present a new extreme point-based rule for packing items inside a three-dimensional container. The extreme point rule is independent from the particular packing problem addressed and can handle additional constraints, such as fixing the position of the items. The new extreme point rule is also used to derive new constructive heuristics for the three-dimensional bin-packing problem. Extensive computational results show the effectiveness of the new heuristics compared to state-of-the-art results. Moreover, the same heuristics, when applied to the two-dimensional bin-packing problem, outperform those specifically designed for the proble
Extended Dynamical Mean Field Theory Study of the Periodic Anderson Model
We investigate the competition of the Kondo and the RKKY interactions in
heavy fermion systems. We solve a periodic Anderson model using Extended
Dynamical Mean Field Theory (EDMFT) with QMC. We monitor simultaneously the
evolution of the electronic and magnetic properties. As the RKKY coupling
increases the heavy fermion quasiparticle unbinds and a local moment forms. At
a critical RKKY coupling there is an onset of magnetic order. Within EDMFT the
two transitions occur at different points and the disapparence of the magnetism
is not described by a local quantum critical point.Comment: 4 pages, 4 figure
Planck-Scale Effects on Global Symmetries: Cosmology of Pseudo-Goldstone Bosons
We consider a model with a small explicit breaking of a global symmetry, as
suggested by gravitational arguments. Our model has one scalar field
transforming under a non-anomalous U(1) symmetry, and coupled lo matter and to
gauge bosons. The spontaneous breaking of the explicitly broken symmetry gives
rise to a massive pseudo-Goldstone boson. We analyze thermal and non-thermal
production of this particle in the early universe, and perform a systematic
study of astrophysical and cosmological constraints on its properties. We find
that for very suppressed explicit breaking the pseudo-Goldstone boson is a cold
dark matter candidate.Comment: 31 pages, 9 figures, Latex file; sections 3 and 4 merged; sections 5
and 6 merged; appendix B removed; to be published in Phys Rev
Severe idiopathic hypereosinophilic syndrome
SummaryHypereosinophilic syndrome (HES) is a systemic illness that usually presents with nonspecific symptoms. However, HES can be fatal, particularly when eosinophils infiltrate vital organs. We report a patient with HES who presented with a perforated viscus and sepsis-like syndrome and rapidly improved with drotrecogin-alfa and steroid therapy
Mimimal Length Uncertainty Principle and the Transplanckian Problem of Black Hole Physics
The minimal length uncertainty principle of Kempf, Mangano and Mann (KMM), as
derived from a mutilated quantum commutator between coordinate and momentum, is
applied to describe the modes and wave packets of Hawking particles evaporated
from a black hole. The transplanckian problem is successfully confronted in
that the Hawking particle no longer hugs the horizon at arbitrarily close
distances. Rather the mode of Schwarzschild frequency deviates from
the conventional trajectory when the coordinate is given by in units of the non local distance legislated
into the uncertainty relation. Wave packets straddle the horizon and spread out
to fill the whole non local region. The charge carried by the packet (in the
sense of the amount of "stuff" carried by the Klein--Gordon field) is not
conserved in the non--local region and rapidly decreases to zero as time
decreases. Read in the forward temporal direction, the non--local region thus
is the seat of production of the Hawking particle and its partner. The KMM
model was inspired by string theory for which the mutilated commutator has been
proposed to describe an effective theory of high momentum scattering of zero
mass modes. It is here interpreted in terms of dissipation which gives rise to
the Hawking particle into a reservoir of other modes (of as yet unknown
origin). On this basis it is conjectured that the Bekenstein--Hawking entropy
finds its origin in the fluctuations of fields extending over the non local
region.Comment: 12 pages (LateX), 1 figur
A STUDY OF THE ANTHROPOMETRIC CHARACTERISTICS OF PERFORMANCE ATHLETES - DIAGNOSIS AND TRAINING GUIDELINES
INTRODUCTION: Anthropometry studies the physical measurements of the human body in order to determine the main characteristics (and their differences) characterizing different individual groups. Many physical measurements are required to describe and differentiate the characteristics, taking into consideration sex, age, and occupational aspects. Performance athletes represent a special category from this point of view, because their activity is highly influenced by the training process, especially when it is not well directed. The present study presents the results obtained by analyzing some important anthropometric characteristics of a female basketball team (first Romanian league).
METHODS: The measurements were made for 10 female basketball players. The criteria employed in appreciating the anthropometric characteristics had in principle a somatophysiologic character. The obtained results were compared with the optimum profile of the basketball player. The body composition was also studied in correlation with dynamometric and miotonometric measurements, using the method of 5 fat tissue layers.
RESULTS: A few of the results obtained are summarized below. From the point of view of orthostatic position, 30% of the subjects had a very good (VG) position, 60% a good (G) position and 10% a bad (B) position (Fig. 1). In Fig. 2 the results are presented for the shape of the thorax (NT-normal thorax, CT-cylindrical thorax, PTplane thorax). An important and delicate aspect of this study was the analysis of body composition. The results were unexpected, all the subjects having a higher percentage of fat tissue than admitted in basketball (>11%).
CONCLUSIONS: The present study analyzes many anthropometric characteristics
of female basketball players. Guidelines for improving the training process are
presented, in conjunction with medical and rehabilitation aspects
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