The Low Energy Limit of the Chern-Simons Theory Coupled to Fermions

We study the nonrelativistic limit of the theory of a quantum Chern--Simons field minimally coupled to Dirac fermions. To get the nonrelativistic effective Lagrangian one has to incorporate vacuum polarization and anomalous magnetic moment effects. Besides that, an unsuspected quartic fermionic interaction may also be induced. As a by product, the method we use to calculate loop diagrams, separating low and high loop momenta contributions, allows to identify how a quantum nonrelativistic theory nests in a relativistic one.Comment: 18 pages, 8 figures, Late

Generation of higher derivatives operators and electromagnetic wave propagation in a Lorentz-violation scenario

We study the perturbative generation of higher-derivative operators as corrections to the photon effective action, which are originated from a Lorentz violation background. Such corrections are obtained, at one-loop order, through the proper-time method, using the zeta function regularization. We focus over the lowest order corrections and investigate their influence in the propagation of electromagnetic waves through the vacuum, in the presence of a strong, constant magnetic field. This is a setting of experimental relevance, since it bases active efforts to measure non linear electromagnetic effects. After surprising cancellations of Lorentz violating corrections to the Maxwell's equation, we show that no effects of the kind of Lorentz violation we consider can be detected in such a context.Comment: v2: 13 pages, no figures, section IV considerably rewritten, main results unchanged and are now obtained in a simpler way. To appear in PL

Interplay of tidal evolution and stellar wind braking in the rotation of stars hosting massive close-in planets

This paper deals with the application of the creep tide theory (Ferraz-Mello, Cel. Mech. Dyn. Astron. vol. 116, 109, 2013) to the study of the rotation of stars hosting massive close-in planets. The stars have nearly the same tidal relaxation factors as gaseous planets and the evolution of their rotation is similar to that of close-in hot Jupiters: they tidally evolve towards a stationary solution. However, stellar rotation may also be affected by stellar wind braking. Thus, while the rotation of a quiet host star evolves towards a stationary attractor with a frequency ($1+6e^2$) times the orbital mean-motion of the companion, the continuous loss of angular momentum in an active star displaces the stationary solution towards slower values: Active host stars with big close-in companions tend to have rotational periods larger than the orbital periods of their companions. The study of some hypothetical examples shows that because of tidal evolution, the rules of gyrochronology cannot be used to estimate the age of one system with a large close-in companion, no matter if the star is quiet or active, if the current semi-major axis of the companion is smaller than 0.03--0.04 AU. Details on the evolution of the systems: CoRoT LRc06E21637, CoRoT-27, Kepler-75, CoRoT-2, CoRoT-18, CoRoT-14 and on hypothetical systems with planets of mass 1--4 M_Jup in orbit around a star similar to the Sun are given.Comment: 22 pages, 8 figures; Publication in Ap

Sistema de produção de leite em pastagem de Capim -Tanzânia: ações de transferência de tecnologia.

bitstream/CPAMN/20173/1/CT185.pd

Acute pancreatitis in children : a tertiary hospital report

INTRODUCTION: The incidence of acute pancreatitis (AP) in children has increased significantly in the past two decades. OBJECTIVE: All cases of AP, acute recurrent pancreatitis (ARP), and chronic pancreatitis examined between May 2002 and May 2012 at Hospital de Braga, Portugal, were reviewed. MATERIAL AND METHODS: Patients were identified by searching the hospital's electronic discharge records for the International Classification of Disease, Ninth Revision (ICD-9) code 577.0 (acute pancreatitis). ARP was considered as two or more episodes of AP per year or more than three episodes over a lifetime with intervening return to baseline. The following data were analyzed: demographic information, clinical, laboratory and imaging test results, etiology of pancreatitis, medical and surgical management, length of hospitalization, and outcome. The clinical and laboratory factors used in the pediatric acute pancreatitis severity score system and computed tomography severity index (CTSI) score were compared between patients with mild and severe disease. RESULTS: A total of 37 patients, 31 episodes of AP and 6 patients with ARP, were documented. The most prevalent etiologies were biliary stones/sludge (24.3%) and trauma (16.2%). Admission elevated white blood cell count (p=0.011), 48-h trough calcium (p=0.007), and 48-h rise in blood urea nitrogen (p=0.025) correlated significantly with disease severity. CTSI on admission had a score below 4 in three patients with severe disease. CONCLUSION: This Portuguese pediatric pancreatitis report highlights the multiple and complex etiology of this disease. Better pediatric scoring systems and management algorithms are needed

On the nature of Lithium-rich giant stars: constraints from Beryllium abundances

We have derived beryllium abundances for 7 Li-rich giant (A(Li) > 1.5) stars and 10 other Li-normal giants, with the aim of investigating the origin of the Lithium in the Li-rich giants. In particular, we test the predictions of the engulfment scenario proposed by Siess & Livio (1999), where the engulfment of a brown dwarf or one or more giant planets would lead to a simultaneous enrichment of 7Li and 9Be. We show that regardless their nature, none of the stars studied in this paper were found to have detectable beryllium. Using simple dilution arguments we show that the engulfment of an external object as the sole source of Li enrichment is ruled out by the Li and Be abundance data. The present results favor the idea that Li has been produced in the interior of the stars by a Cameron-Fowler process and brought up to the surface by an extra mixing mechanism.Comment: Accepted in A&

Comportamento de cultivares de Cynodon no Piauí.

bitstream/CPAMN-2009-09/17159/1/CT146.pd