12,101 research outputs found
Canonical Transformations in a Higher-Derivative Field Theory
It has been suggested that the chiral symmetry can be implemented only in
classical Lagrangians containing higher covariant derivatives of odd order.
Contrary to this belief, it is shown that one can construct an exactly soluble
two-dimensional higher-derivative fermionic quantum field theory containing
only derivatives of even order whose classical Lagrangian exhibits chiral-gauge
invariance. The original field solution is expressed in terms of usual Dirac
spinors through a canonical transformation, whose generating function allows
the determination of the new Hamiltonian. It is emphasized that the original
and transformed Hamiltonians are different because the mapping from the old to
the new canonical variables depends explicitly on time. The violation of
cluster decomposition is discussed and the general Wightman functions
satisfying the positive-definiteness condition are obtained.Comment: 12 pages, LaTe
Extended-release niacin increases anti-apolipoprotein A-I antibodies that block the antioxidant effect of high-density lipoprotein-cholesterol: the EXPLORE clinical trial.
Extended-release niacin (ERN) is the most effective agent for increasing high-density lipoprotein-cholesterol (HDL-C). Having previously identified anti-HDL antibodies, we investigated whether ERN affected the antioxidant capacity of HDL and whether ERN was associated with the production of antibodies against HDL (aHDL) and apolipoprotein A-I (aApoA-I).
METHODS:
Twenty-one patients older than 18 years, with HDL-C ≤40 mg dl-1 (men) or ≤50 mg dl-1 (women) were randomly assigned to receive daily ERN (n = 10) or placebo (n = 11) for two sequential 12-week periods, with 4 weeks of wash-out before cross-over. Primary outcome was change of paraoxonase-1 (PON1) activity and secondary outcomes were changes in aHDL and aApoA-I antibodies. Clinical Trial Unique Identifier: EudraCT 2006-006889-42.
RESULTS:
The effect of ERN on PON1 activity was nonsignificant (coefficient estimate 20.83 U l-1 , 95% confidence interval [CI] -9.88 to 51.53; P = 0.184). ERN was associated with an increase in HDL-C levels (coefficient estimate 5.21 mg dl-1 , 95% CI 1.16 to 9.25; P = 0.012) and its subclasses HDL2 (coefficient estimate 2.46 mg dl-1 , 95% CI 0.57 to 4.34; P = 0.011) and HDL3 (coefficient estimate 2.73 mg dl-1 , 95% CI 0.47 to 4.98; P = 0.018). ERN was significantly associated with the production of aApoA-I antibodies (coefficient estimate 0.25 μg ml-1 , 95% CI 0.09-0.40; P = 0.001). aApoA-I titres at baseline were correlated with decreased PON activity.
CONCLUSIONS:
The rise in HDL-C achieved with ERN was not matched by improved antioxidant capacity, eventually hampered by the emergence of aApoA-I antibodies. These results may explain why Niacin and other lipid lowering agents fail to reduce cardiovascular risk.info:eu-repo/semantics/publishedVersio
Six New Galactic Orbits of Globular Clusters in a Milky-Way-Like Galaxy
Absolute proper motions for six new globular clusters have recently been
determined. This motivated us to obtain the Galactic orbits of these six
clusters both in an axisymmetric Galactic potential and in a barred potential,
such as the one of our Galaxy. Orbits are also obtained for a Galactic
potential that includes spiral arms. The orbital characteristics are compared
and discussed for these three cases. Tidal radii and destruction rates are also
computed and discussed.Comment: 29 pages, 11 figures. Accepted for publication in Ap
Simulation and Teaching-Learning in Paediatrics. Essential Topics
Em 2004 começou a funcionar no Hospital de Dona Estefânia um Centro de Simulação de Técnicas em Pediatria ligado à Faculdade de Ciências Médicas da Universidade Nova de Lisboa. A principal inovação relacionou-se com o facto de os estudantes do 5º ano do curso passarem a dispor da oportunidade
de treino de procedimentos em modelos (manequins).
O objectivo deste estudo foi descrever o funcionamento do referido centro com base nos testemunhos de estudantes e na
experiência dos formadores.
De acordo com as opiniões expressas, este tipo de treino foi considerado muito relevante para a sua formação. Na generalidade, os estudantes expressaram a necessidade de ampliar a carga horária para esta valência e de maior diversificação de
manequins. De acordo com a experiência dos formadores há necessidade de melhorar alguns aspectos relacionados com a logística, e de rendibilizar a utilização do equipamento, abrindo esta área de formação ao ensino pós-graduado nomeadamente ao treino de internos, o que implica um alargamento do protocolo estabelecido entre a Faculdade e o Hospital.
Em síntese, reconhecendo embora, as limitações do estudo, os testemunhos de docentes e discentes podem ser considerados
como auditoria interna, sugerindo a necessidade de mudanças curriculares e de melhoria de aspectos logísticos essenciais
Percolative phase transition on ferromagnetic insulator manganites: uncorrelated to correlated polaron clusters
In this work, we report an atomic scale study on the ferromagnetic insulator
manganite LaMnO using PAC spectroscopy. Data analysis
reveals a nanoscopic transition from an undistorted to a Jahn-Teller-distorted
local environment upon cooling. The percolation thresholds of the two local
environments enclose a macroscopic structural transition
(Rhombohedric-Orthorhombic). Two distinct regimes of JT-distortions were found:
a high temperature regime where uncorrelated polaron clusters with severe
distortions of the MnO octahedra survive up to
and a low temperature regime where correlated regions have a weaker
JT-distorted symmetry.Comment: 4 pages, 4 Figures, submitted to PRL, new version with more data,
text reformulate
On fermionic tilde conjugation rules and thermal bosonization. Hot and cold thermofields
A generalization of Ojima tilde conjugation rules is suggested, which reveals
the coherent state properties of thermal vacuum state and is useful for the
thermofield bosonization. The notion of hot and cold thermofields is introduced
to distinguish different thermofield representations giving the correct normal
form of thermofield solution for finite temperature Thirring model with correct
renormalization and anticommutation properties.Comment: 13 page
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