603 research outputs found
Quons as su(2) Irreducible Tensor Operators
We prove that, for the quon algebra, which interpolates between the Bose and
Fermi statistics and depends on a free parameter q,it is possible to build an
su(2) irreducible representation. One of the consequences of this fact is that
the quons couple via the same angular momentum coupling rules obeyed by
ordinary bosons and fermions.Comment: 8 pages,Late
Quons Restricted to the Antisymmetric Subspace: Formalism and Applications
In this work we develop a formalism to treat quons restricted to the
antisymmetric part of their many-body space. A model in which a system of
identical quons interact through a pairing force is then solved within this
restriction and the differences between our solution and the usual fermionic
model solution are then presented and discussed in detail. Possible connections
to physical systems are also considered.Comment: 12 pages, 3 figure
Asymptotically Improved Convergence of Optimized Perturbation Theory in the Bose-Einstein Condensation Problem
We investigate the convergence properties of optimized perturbation theory,
or linear expansion (LDE), within the context of finite temperature
phase transitions. Our results prove the reliability of these methods, recently
employed in the determination of the critical temperature T_c for a system of
weakly interacting homogeneous dilute Bose gas. We carry out the explicit LDE
optimized calculations and also the infrared analysis of the relevant
quantities involved in the determination of in the large-N limit, when
the relevant effective static action describing the system is extended to O(N)
symmetry. Then, using an efficient resummation method, we show how the LDE can
exactly reproduce the known large-N result for already at the first
non-trivial order. Next, we consider the finite N=2 case where, using similar
resummation techniques, we improve the analytical results for the
nonperturbative terms involved in the expression for the critical temperature
allowing comparison with recent Monte Carlo estimates of them. To illustrate
the method we have considered a simple geometric series showing how the
procedure as a whole works consistently in a general case.Comment: 38 pages, 3 eps figures, Revtex4. Final version in press Phys. Rev.
Dependence of Variational Perturbation Expansions on Strong-Coupling Behavior. Inapplicability of delta-Expansion to Field Theory
We show that in applications of variational theory to quantum field theory it
is essential to account for the correct Wegner exponent omega governing the
approach to the strong-coupling, or scaling limit. Otherwise the procedure
either does not converge at all or to the wrong limit. This invalidates all
papers applying the so-called delta-expansion to quantum field theory.Comment: Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper (including all PS fonts) at
http://www.physik.fu-berlin.de/~kleinert/34
Implante curto unitário em região posterior de mandíbula: relato de caso clínico / Short unitary implantation in the posterior mandible region: a clinical case report
Com a perda precoce dos dentes posteriores e o uso de próteses móveis inferiores, é comum haver severa reabsorção e baixa disponibilidade óssea em região posterior de mandíbula, dificultando a instalação de implantes de dimensões convencionais. Desta forma, alternativas cirúrgicas são necessárias para a reabilitação de pacientes com estas características. Dentre as possibilidades, a instalação de implantes curtos (<10mm) é o procedimento menos invasivo e que possui a menor morbidade pós-operatória, além de menos oneroso. Mesmo com eficácia comprovada para o seu uso, verifica-se a necessidade de tomar certos cuidados em sua indicação, bem como sua execução. Para compensar o menor tamanho deve-se observar fatores como: qualidade óssea, proporção coroa/implante, número de implantes e diâmetro, magnitude das forças e mesa oclusal. Neste trabalho será relatado um caso clínico de implante curto Straumann 4.1 X 6mm unitário instalado em região posterior de mandíbula com pouca disponibilidade óssea para instalação de implante convencional
On the Convergence of the Linear Delta Expansion for the Shift in T_c for Bose-Einstein Condensation
The leading correction from interactions to the transition temperature T_c
for Bose-Einstein condensation can be obtained from a nonperturbative
calculation in the critical O(N) scalar field theory in 3 dimensions with N=2.
We show that the linear delta expansion can be applied to this problem in such
a way that in the large-N limit it converges to the exact analytic result. If
the principal of minimal sensitivity is used to optimize the convergence rate,
the errors seem to decrease exponentially with the order in the delta
expansion. For N=2, we calculate the shift in T_c to fourth order in delta. The
results are consistent with slow convergence to the results of recent lattice
Monte Carlo calculations.Comment: 26 pages, latex, 8 figure
In vivo assessment of possible probiotic properties of Zymomonas mobilis in a Wistar rat model
In recent years the incorporation of probiotic bacteria into foods has
received increasing scientific interest for health promotion and
disease prevention. The safety and probiotic properties of Zymomonas
mobilis CP4 (UFPEDA-202) was studied in a Wistar rat model fed the
109 colony forming units (cfu)/mL-1 of the assayed strain for 30 days.
No abnormal clinical signs were noted in the group receiving viable
cells of Z. mobilis and water (control) during the period of the
experiment. There were no significant difference (p > 0.05) in feed
intake and weight gain among mice fed the Z. mobilis in comparison to
the control group. No bacteria were found in blood, liver and spleen of
any animals. Mice receiving Z. mobilis showed significantly differences
(p < 0.05) in total and differential leucocytes count, excepting for
neutrophils, after the experimental period. Otherwise, it was not found
in control group. Histological examination showed that feeding mice
with Z. mobilis caused no signs of adverse effects on gut, liver and
spleen. From these results, Z. mobilis CP4 (UFEPEDA-202) is likely to
be nonpathogenic and safe for consumption, and could have a slight
modulating effect on immunological performance in mice
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