Infinite-dimensional representations of the rotation group and Dirac's monopole problem

Within the context of infinite-dimensional representations of the rotation group the Dirac monopole problem is studied in details. Irreducible infinite-dimensional representations, being realized in the indefinite metric Hilbert space, are given by linear unbounded operators in infinite-dimensional topological spaces, supplied with a weak topology and associated weak convergence. We argue that an arbitrary magnetic charge is allowed, and the Dirac quantization condition can be replaced by a generalized quantization rule yielding a new quantum number, the so-called topological spin, which is related to the weight of the Dirac string.Comment: JHEP style. Extended version of hep-th/0403146. Revised version, title and some notations are changed. References and Appendix B are adde

Clinical and surgical assistance in prostate cancer during the COVID-19 Pandemic: Implementation of assistance protocols

Purpose: Propose an approach of prostate cancer (PCa) patients during COVID-19 pandemic. Material and Methods: We conducted a review of current literature related to surgical and clinical management of patients during COVID-19 crisis paying special attention to oncological ones and especially those suffering from PCa. Based on these publications and current urological guidelines, a manual to manage PCa patients is suggested. Results: Patients suffering from cancer are likely to develop serious complications from COVID-19 disease together with an increased risk of postoperative morbidity and mortality. Therefore, the management of oncological patients should be taken into special consideration and most of the treatments postponed. In case the procedure is not deferrable, it should be adapted to the current situation. While the shortest radiotherapy (RT) regimens should be applied, surgical procedures must undergo the following recommendations proposed by main surgical associations. PCa prognosis is generally favourable and therefore one can safely delay most of the biopsies up to 6 months without interfering with survival outcomes in the vast majority of cases. In the same way, most of the localised PCa patients are suitable for active surveillance (AS) or hormonal therapy until local definitive treatment could be reconsidered. In metastatic as well as castration resistant PCa stages, adding androgen receptor targeted agents (abiraterone, apalutamide, darolutamide or enzalutamide) to androgen-deprivation therapy (ADT) could be considered in high risk patients. On the contrary, chemotherapy, immunotherapy and Radium-223 must be avoided with regard to the consequence of hematologic toxicity and risk of COVID-19 infection because of immunodepression. Conclusions: Most of the biopsies should be delayed while AS is advised in those patients with low risk PCa. ADT allows us to defer definitive local treatment in many cases of intermediate and high risk PCa. In regard to metastatic and castration resistant PCa, combination therapies with abiraterone, apalutamide, darolutamide or enzalutamide could be considered. Chemotherapy, Radium-223 and immunotherapy are discouraged

Empirical modeling of low-frequency dispersive effects due to traps and thermal phenomena in III-V FET's

The modeling of low-frequency dispersive effects due to surface state densities, deep level traps and thermal phenomena plays an important role in the large-signal performance prediction of III-V FET's. This paper describes an empirical modeling approach to accurately predict deviations between static and dynamic drain current characteristics caused by dispersive effects in III-V devices operating at microwave frequencies. It is based on reasonable assumptions and can easily be embedded in nonlinear FET models to be used in Harmonic-Balance tools for circuit analysis and design. Experimental and simulated results, for HEMT's and GaAs MESFET's of different manufacturers, that confirm the validity of the new approach, are presented and discussed together with the characterization procedures require

Phenology of copaíba (Copaifera langsdorffii Desf. -- Leguminosae, Caesalpinioideae) in a semideciduous forest, southeastern Brazil

Plant phenology is concerned with the timing of recurring events, and is poorly known for tropical forest species, although this ecosystem has the greatest diversity of phenological patterns. A phenological study was carried out from February/1991 to April/1993. Thirty six trees were systematically observed biweekly for changes on leaf fall, leaf flushing, flowering and fruiting. Leaf fall and flushing were synchronized phases. These events always occurred at the end of dry season (leaf fall) and start of rainy season (leaf flushing) being clearly related with precipitation. The flowering occurred in the rainy season, and fruiting during the dry season. Fruiting did not show an annual cycle, but years which massive fruiting being followed by non productive years. Other non climatic factors, like seed dispersers and seed predators were also likely to affect fruiting.A fenologia da emissão foliar, floração e frutificação para espécies de florestas tropicais é pouco conhecida, embora estes ecossistemas apresentem grande diversidade de padrões fenológicos. Foi estudada, de fevereiro de 1991 a abril de 1993, a fenologia da copaíba (Copaifera langsdorffii Desf.) na Reserva de Santa Genebra. Foram feitas observações em 36 indivíduos e analisadas queda de folhas, brotamento, floração e frutificação. A queda de folhas e o brotamento foram as fenofases mais sincronizadas dentro da população. Estes eventos ocorreram no final da estação seca (queda de folhas) e início da estação chuvosa (brotamento) e foram relacionados principalmente com a precipitação. A floração ocorreu na estação chuvosa e a frutificação na estação seca. A frutificação ocorreu em ciclos supra-anuais, com anos de produção intensa seguidos de anos sem frutificação. Além dos fatores climáticos, as interações com dispersores e predadores de sementes também parecem influenciar o padrão de frutificação observado em Copaifera langsdorffii

Preferred growth direction of III-V nanowires on differently oriented Si substrates

One of the nanowire characteristics is its preferred elongation direction. Here, we investigated the impact of Si substrate crystal orientation on the growth direction of GaAs nanowires. We first studied the self-catalyzed GaAs nanowire growth on Si (111) and Si (001) substrates. SEM observations show GaAs nanowires on Si (001) are grown along four directions without preference on one or some of them. This non-preferential nanowire growth on Si (001) is morphologically in contrast to the extensively reported vertical preferred GaAs nanowire growth on Si (111) substrates. We propose a model based on the initial condition of an ideal Ga droplet formation on Si substrates and the surface free energy calculation which takes into account the dangling bond surface density for different facets. This model provides further understanding of the different preferences in the growth of GaAs nanowires along selected directions depending on the Si substrate orientation. To verify the prevalence of the model, nanowires were grown on Si (311) substrates. The results are in good agreement with the three-dimensional mapping of surface free energy by our model. This general model can also be applied to predictions of nanowire preferred growth directions by the vapor-liquid-solid growth mode on other group IV and III-V substrates

Pharmacological Interventions to Ameliorate Neuropathological Symptoms in a Mouse Model of Lafora Disease

14 páginas; 9 figuras.Lafora disease (LD, OMIM 254780) is a rare fatal neurodegenerative disorder that usually occurs during childhood with generalized tonic-clonic seizures, myoclonus, absences, drop attacks or visual seizures. Unfortunately, at present, available treatments are only palliatives and no curative drugs are available yet. The hallmark of the disease is the accumulation of insoluble polyglucosan inclusions, called Lafora bodies (LBs), within the neurons but also in heart, muscle and liver cells. Mouse models lacking functional EPM2A or EPM2B genes (the two major loci related to the disease) recapitulate the Lafora disease phenotype: they accumulate polyglucosan inclusions, show signs of neurodegeneration and have a dysregulation of protein clearance and endoplasmic reticulum stress response. In this study, we have subjected a mouse model of LD (Epm2b-/-) to different pharmacological interventions aimed to alleviate protein clearance and endoplasmic reticulum stress. We have used two chemical chaperones, trehalose and 4-phenylbutyric acid. In addition, we have used metformin, an activator of AMP-activated protein kinase (AMPK), as it has a recognized neuroprotective role in other neurodegenerative diseases. Here, we show that treatment with 4-phenylbutyric acid or metformin decreases the accumulation of Lafora bodies and polyubiquitin protein aggregates in the brain of treated animals. 4-Phenylbutyric acid and metformin also diminish neurodegeneration (measured in terms of neuronal loss and reactive gliosis) and ameliorate neuropsychological tests of Epm2b-/- mice. As these compounds have good safety records and are already approved for clinical uses on different neurological pathologies, we think that the translation of our results to the clinical practice could be straightforward.This work was supported by grants from the Spanish Ministry of Education and Science SAF2011-27442, Fundació La Marato de TV3 (ref. 100130) and an ACCI2012 action from CIBERER. A.B. holds a postdoctoral fellowship from the Program “Junta para la Ampliación de Estudios” (JAE-Doc) co-funded by the European Social Fund (ESF).Peer reviewe

Tailoring Anderson localization by disorder correlations in 1D speckle potentials

We study Anderson localization of single particles in continuous, correlated, one-dimensional disordered potentials. We show that tailored correlations can completely change the energy-dependence of the localization length. By considering two suitable models of disorder, we explicitly show that disorder correlations can lead to a nonmonotonic behavior of the localization length versus energy. Numerical calculations performed within the transfer-matrix approach and analytical calculations performed within the phase formalism up to order three show excellent agreement and demonstrate the effect. We finally show how the nonmonotonic behavior of the localization length with energy can be observed using expanding ultracold-atom gases

Fatty Acids in the Meat of Buffaloes Supplemented with Fish Oil

The purpose of this study has been to investigate the influence of both a supplementary fish oil diet on conjugated linoleic acid (CLA) and n6 and n3 fatty acids on intramuscular fat in Mediterranean buffalo meat. Twenty animals were randomly divided into two groups and fed with Brachiaria brizantha, 3Kg rice bran, 500 g corn and 500 g sunflower pellets for 60 days. Group I received this diet only while in group II each animal received additional 100 ml fish oil daily. Results indicated a significant decrease of palmitic fatty acid in group II (232.67 mg/g fat) in relation to group I (254.73 mg/g fat). Among unsaturated acids (AGI), the 9c 11t CLA value of group II (21.23 mg/g fat) showed an increase in relation to group I (15.80 mg/g fat), while the linoleic acid content of group II (28,85 mg/g fat) decreased significantly in relation to group I (47,00 mg/g fat). However, the alpha linolenic acid showed no significant difference between the supplemented diet group and the control group (10.31 and 10.70 mg/g fat, respectively). Group II n6/n3 ratio was narrower (2.69:1) than that of group I (4.55:1). Summing up, group II diet, which included fish oil, increased the CLA content in intramuscular fat and decreased the n6 fatty acids, improving the n6/n3 ratio

Quantum effective actions from nonperturbative worldline dynamics

We demonstrate the feasibility of a nonperturbative analysis of quantum field theory in the worldline formalism with the help of an efficient numerical algorithm. In particular, we compute the effective action for a super-renormalizable field theory with cubic scalar interaction in four dimensions in quenched approximation (small-$N_f$ expansion) to all orders in the coupling. We observe that nonperturbative effects exert a strong influence on the infrared behavior, rendering the massless limit well defined in contrast to the perturbative expectation. Our numerical method is based on a direct use of probability distributions for worldline ensembles, preserves all Euclidean spacetime symmetries, and thus represents a new nonperturbative tool for an investigation of continuum quantum field theory.Comment: 33 pages, 10 figure