14,103 research outputs found
Plasma and testicular testosterone levels, volume density and number of Leydig cells and spermatogenic efficiency of rabbits
Plasma and tissue testosterone concentrations were determined by radioimmunoassay in 12 eight-month-old sexually mature New Zealand White rabbits and evaluated for possible associations with spermatogenic efficiency as well as with volume density and number of Leydig cells. Testicular tissue was processed histologically and histometry was performed in order to quantify germ cells, Sertoli cells and Leydig cells. Spermatogenic efficiency, reported as the ratios among germ cells (spermatogonia, primary spermatocytes and round spermatids) and by the ratio of germ cells to Sertoli cells, was not associated with testosterone levels. However, Leydig cell parameters such as number of Leydig cells per gram of testis, total number of Leydig cells per testis and percent cell volume of Leydig cell nuclei were correlated significantly with testosterone levels. The statistically significant correlation (r = 0.82, P\u3c0.05) observed between testosterone levels and the number of Leydig cells per gram of testis suggests that, in the rabbit, the latter parameter can serve as a criterion for monitoring testosterone levels in this species under normal conditions
Entanglement versus mixedness for coupled qubits under a phase damping channel
Quantification of entanglement against mixing is given for a system of
coupled qubits under a phase damping channel. A family of pure initial joint
states is defined, ranging from pure separable states to maximally entangled
state. An ordering of entanglement measures is given for well defined initial
state amount of entanglement.Comment: 9 pages, 2 figures. Replaced with final published versio
Automatic speaker segmentation using multiple features and distance measures: a comparison of three approaches
This paper addresses the problem of unsupervised speaker change detection. Three systems based on the Bayesian Information Criterion (BIC) are tested. The first system investigates the AudioSpectrumCentroid and the AudioWaveformEnvelope features, implements a dynamic thresholding followed by a fusion scheme, and finally applies BIC. The second method is a real-time one that uses a metric-based approach employing the line spectral pairs and the BIC to validate a potential speaker change point. The third method consists of three modules. In the first module, a measure based on second-order statistics is used; in the second module, the Euclidean distance and T2 Hotelling statistic are applied; and in the third module, the BIC is utilized. The experiments are carried out on a dataset created by concatenating speakers from the TIMIT database, that is referred to as the TIMIT data set. A comparison between the performance of the three systems is made based on t-statistics
Cultivares de mandioca de mesa da AmazĂ´nia Oriental.
bitstream/item/52971/1/PesquisaAnd040001.pd
The pros and cons of using SDL for creation of distributed services
In a competitive market for the creation of complex distributed services, time to market, development cost, maintenance and flexibility are key issues. Optimizing the development process is very much a matter of optimizing the technologies used during service creation. This paper reports on the experience gained in the Service Creation projects SCREEN and TOSCA on use of the language SDL for efficient service creation
Ultrarelativistic boost of spinning black rings
We study the D=5 Emparan-Reall spinning black ring under an ultrarelativistic
boost along an arbitrary direction. We analytically determine the resulting
shock pp-wave, in particular for boosts along axes orthogonal and parallel to
the plane of rotation. The solution becomes physically more interesting and
simpler if one enforces equilibrium between the forces on the ring. We also
comment on the ultrarelativistic limit of recently found supersymmetric black
rings with two independent angular momenta. Essential distinct features with
respect to the boosted Myers-Perry black holes are pointed out.Comment: 15 pages, 2 figures. v2: added multipole expansions at spatial
infinity, and a comparison with the boosted Myers-Perry solution in a new
appendix. To appear in JHE
Decoherence induced by a phase-damping reservoir
A phase damping reservoir composed by -bosons coupled to a system of
interest through a cross-Kerr interaction is proposed and its effects on
quantum superpo sitions are investigated. By means of analytical calculations
we show that: i-) the reservoir induces a Gaussian decay of quantum coherences,
and ii-) the inher ent incommensurate character of the spectral distribution
yields irreversibility . A state-independent decoherence time and a master
equation are both derived an alytically. These results, which have been
extended for the thermodynamic limit, show that nondissipative decoherence can
be suitably contemplated within the EI D approach. Finally, it is shown that
the same mechanism yielding decoherence ar e also responsible for inducing
dynamical disentanglement.Comment: 8 pages, 3 figure
Eccentric binary black-hole mergers: The transition from inspiral to plunge in general relativity
We study the transition from inspiral to plunge in general relativity by
computing gravitational waveforms of non-spinning, equal-mass black-hole
binaries. We consider three sequences of simulations, starting with a
quasi-circular inspiral completing 1.5, 2.3 and 9.6 orbits, respectively, prior
to coalescence of the holes. For each sequence, the binding energy of the
system is kept constant and the orbital angular momentum is progressively
reduced, producing orbits of increasing eccentricity and eventually a head-on
collision. We analyze in detail the radiation of energy and angular momentum in
gravitational waves, the contribution of different multipolar components and
the final spin of the remnant. We find that the motion transitions from
inspiral to plunge when the orbital angular momentum L=L_crit is about 0.8M^2.
For L<L_crit the radiated energy drops very rapidly. Orbits with L of about
L_crit produce our largest dimensionless Kerr parameter for the remnant,
j=J/M^2=0.724. Generalizing a model recently proposed by Buonanno, Kidder and
Lehner to eccentric binaries, we conjecture that (1) j=0.724 is the maximal
Kerr parameter that can be obtained by any merger of non-spinning holes, and
(2) no binary merger (even if the binary members are extremal Kerr black holes
with spins aligned to the orbital angular momentum, and the inspiral is highly
eccentric) can violate the cosmic censorship conjecture.Comment: Added sequence of long inspirals to the study. To match published
versio
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