Operator Ordering in Quantum Radiative Processes

In this work we reexamine quantum electrodynamics of atomic eletrons in the Coulomb gauge in the dipole approximation and calculate the shift of atomic energy levels in the context of Dalibard, Dupont-Roc and Cohen-Tannoudji (DDC) formalism by considering the variation rates of physical observables. We then analyze the physical interpretation of the ordering of operators in the dipole approximation interaction Hamiltonian in terms of field fluctuations and self-reaction of atomic eletrons, discussing the arbitrariness in the statistical functions in second order bound-state perturbation theory.Comment: Latex file, 12 pages, no figures, includes PACS numbers and minor changes in the text with the addition of a new sectio

Convexity of reduced energy and mass angular momentum inequalities

In this paper, we extend the work in \cite{D}\cite{ChrusLiWe}\cite{ChrusCo}\cite{Co}. We weaken the asymptotic conditions on the second fundamental form, and we also give an $L^{6}-$norm bound for the difference between general data and Extreme Kerr data or Extreme Kerr-Newman data by proving convexity of the renormalized Dirichlet energy when the target has non-positive curvature. In particular, we give the first proof of the strict mass/angular momentum/charge inequality for axisymmetric Einstein/Maxwell data which is not identical with the extreme Kerr-Newman solution.Comment: 27 page

Vascular and apoptotic changes in the placode of myelomeningocele mice during the final stages of in utero development

JOAQUIM L. REIS, M.D., PH.D.,1,2 JORGE CORREIA-PINTO, M.D., PH.D.,3,4 MARIANA P. MONTEIRO, M.D., PH.D.,1 MADALENA COSTA, B.SC.,1 AND GROVER M. HUTCHINS, M.D.5 1Department of Anatomy, Abel Salazar Institute for the Biomedical Sciences and Unit for Multidisciplinary Biomedical Research, University of Porto; 2Department of Neurosurgery, Santo António General Hospital; 4Department of Pediatric Surgery, São João Hospital, Porto; 3Life and Health Sciences Research Institute, School of Health Sciences, University of Minho, Braga, Portugal; and 5Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland Object. Myelomeningocele (MMC) is a primary neurulation defect that is associated with devastating neurological disabilities in affected newborns. To better characterize the in utero neurodegenerative process of MMC, the authors investigated the changes in vascular organization, apoptosis, and the presence of inflammatory cells during gestation by using a mutant mouse model of MMC. Methods. The curly tail/loop tail (ct/lp) mutant mouse model of MMC was chosen to obtain fetuses at different stages of gestation. Mouse fetuses harboring MMC were harvested by caesarean section at embryonic Days 14.5, 16.5, and 18.5 (complete mouse gestation at 19 days, 6 mice/group); littermate fetuses with the same gestational age but without an MMC were used as controls. Samples of the MMC placode or normal spinal cord were stained for immunocytochemical labeling with caveolin antibody (endothelium marker) and activated caspase-3 antibody (apoptosis marker). Samples were morphometrically analyzed with a computer-assisted image analyzer. Results. The MMC mice presented with an increase in vascular density from embryonic Days 16.5–18.5 and an enhanced number of apoptotic cells at embryonic Day 18.5, compared with controls. There were scarce signals of an inflammatory reaction in the MMC placode, as a few infiltrating neutrophils were seen only at embryonic Day 18.5. Conclusions. Fetal placodes in MMC mice showed evidence of increased vascular density since embryonic Day 16.5 and increased apoptosis at embryonic Day 18.5. These new data support the view that in utero changes of the MMC placode, occurring during the last stages of gestation, contribute to the neuropathological manifestations in fullterm newborns with MMC. (DOI: 10.3171/PED/2008/2/8/150

Ladder type operators and recurrence relations for the radial wave functions of the N-th dimensional oscillators and hydrogenlike atoms

Using the method described in [11], we present some new ladder type operators and recurrence relations for the radial wave functions of the N-th dimensional isotropic harmonic oscillators and the hydrogenlike atoms

Quinze anos de monitorização das comunidades biológicas do estuário do Tejo no âmbito da construção e funcionamento das ETARs do Portinho da Costa e da Mutela (Concelho de Almada): Experiência adquirida e ensinamentos para futuros casos semelhantes.

Desde 2001 que a Câmara Municipal de Almada tem vindo a promover, em colaboração com o MARE, a monitorização ambiental das regiões estuarinas sob influência das ETARs do Portinho da Costa e da Mutela, que vieram substituir efluentes não tratados emitidos sensivelmente nas mesmas regiões. O objetivo deste programa de monitorização consiste em avaliar as principais alterações ocorridas (na maioria dos casos positivas) nos ecossistemas estuarinos dos vários locais, após a entrada em funcionamento de ambas as infraestruturas. Estes 15 anos de estudos das comunidades bentónicas e de peixes locais têm permitido identificar variações nos padrões espácio-temporais destes compartimentos biológicos e identificar quais dessas evoluções podem ser presumivelmente relacionáveis com o funcionamento das infraestruturas e quais derivam provavelmente de flutuações naturais. Nesta comunicação são enunciados os pressupostos do estudo, descritos os delineamentos experimentais e metodologias de tratamento dos dados adotados, apresentados os principais resultados obtidos e discutidas as grandes dificuldades sentidas para cumprir os objetivos estabelecidos. Este conjunto de elementos será analisado numa perspetiva de como a experiência adquirida pode ser útil, no futuro, para casos semelhantes, sobretudo numa ótica da correta identificação dos verdadeiros efeitos infraestruturais e de despiste da influência de outros fatores concorrentes

Can a restocking event with European (glass) eels cause early changes in local biological communities and its ecological status?

In an attempt to assist the recovery of the panmictic population of the European eel, declining since the late 1980s, the restocking of areas with low or no natural recruitment has been one of the measures adopted to reverse this trend. However, the main focus in several monitoring programmes for these actions, has been in the best interest of its viability and cost/benefit relationships and, for that, the condition of the released stocks has been the main concern. Yet, so far, no studies have assessed the potential ecological impacts that restocking might have on other biological communities. This pioneer pilot study aimed to evaluate the early ecological impact of a restocking event on other biological communities, considering inter-specific competition (other fish species) and feeding impact (macroinvertebrates).The reference condition of the biological communities of an inland tributary of the Mondego river, the River Ceira, was determined in three sites inaccessible to the natural recruitment of eels, followed by a post-stocking assessment. The results showed no significant changes in the fish assemblages in restocked areas, contrary to the macroinvertebrate community. However, the ecological status for the macroinvertebrate community showed no deleterious effects, with the results suggesting exactly the opposite. This may be related to the low density of the restocked eels and factors influencing the local trophic web. This study confirms the suitability of the habitat for restocking with glass eels, during its early stages, without disrupting the local ecological status, using densities close to those of natural recruitment