Entanglement entropy in de Sitter space

We compute the entanglement entropy for some quantum field theories on de Sitter space. We consider a superhorizon size spherical surface that divides the spatial slice into two regions, with the field theory in the standard vacuum state. First, we study a free massive scalar field. Then, we consider a strongly coupled field theory with a gravity dual, computing the entanglement using the gravity solution. In even dimensions, the interesting piece of the entanglement entropy is proportional to the number of e-foldings that elapsed since the spherical region was inside the horizon. In odd dimensions it is contained in a certain finite piece. In both cases the entanglement captures the long range correlations produced by the expansion

High-scale inflation and the tensor tilt

In this paper, we explore a novel observational signature of gravitational corrections during slow-roll inflation. We study the coupling of the inflaton field to higher-curvature tensors in models with a minimal breaking of conformal symmetry. In that case, the most general correction to the tensor two-point function is captured by a coupling to the square of the Weyl tensor. We show that these scenarios lead to a correction to the tilt of the tensor power spectrum and hence a violation of the tensor consistency condition. We arrive at the same conclusion through an analysis in conformal perturbation theory

Partially massless fields during inflation

The representation theory of de Sitter space allows for a category of partially massless particles which have no flat space analog, but could have existed during inflation. We study the couplings of these exotic particles to inflationary perturbations and determine the resulting signatures in cosmological correlators. When inflationary perturbations interact through the exchange of these fields, their correlation functions inherit scalings that cannot be mimicked by extra massive fields. We discuss in detail the squeezed limit of the tensor-scalar-scalar bispectrum, and show that certain partially massless fields can violate the tensor consistency relation of single-field inflation. We also consider the collapsed limit of the scalar trispectrum, and find that the exchange of partially massless fields enhances its magnitude, while giving no contribution to the scalar bispectrum. These characteristic signatures provide clean detection channels for partially massless fields during inflation

Experimental characterization of a 6.7 GHz coaxial Bragg reflector

A coaxial line periodically loaded by circular disks on the inner conductor is designed and constructed to act as Bragg reflector in the 4.0-9.5 GHz frequency range. This is achieved by placing 10 disks (0.35 cm thick and 6.22 cm in diameter) equally spaced by the periodic distance of 1.8 cm on a coaxial waveguide with inner and outer diameters of 6.90 and 4.22 cm. Experiments on a periodic structure made from stainless steel demonstrate a band gap of 5.6 GHz centered at the 6.7 GHz design frequency in close agreement with 3D microwave computer simulations. © 2007 American Institute of Physics

Investigation of ultra-high sensitivity klystron cavity transducers for broadband resonant-mass gravitational wave detectors

Since the Stanford pioneering work of Paik in the 1970s, cryogenic resonant-mass gravitational wave detectors have used resonant transducers, which have the effect of increasing both the detector sensitivity and bandwidth. Now nanotechnology is opening new possibilities towards the construction of ultra-high sensitivity klystron cavity transducers. It might be feasible to construct TeraHz/micron parametric transducers in a near future. They would be so sensitive that there would be no need for multimode resonant transducers. The resonant-antenna would act as a broadband detector for gravitational waves. A spherical antenna, such as Schenberg or Mini-Grail, could add to this quality the advantage of wave position and polarity determination. Here we propose an extreme geometry for a re-entrant klystron cavity (df/dg ∼ 1018 Hz/m, where f stands for the microwave pump frequency and g for variations in the cavity gap), obtaining a frequency response for the strain sensitivity of the Schenberg gravitational wave detector such that its bandwidth increases from 50 Hz (using the so-called resonant mode coupling) to ∼4000 Hz when operating @ 20 mK, and, when compared to LIGO experimental curve, shows a competitive band of about 2000 Hz. We also study some of the technological complications that can be foreseen to design such a resonant cavity. © 2008 IOP Publishing Ltd

Spontaneous fractures secondary to primary hyperparathyroidism in pregnancy: a case report / Fracturas espontâneas secundárias ao hiperparatiroidismo primário na gravidez: um relato de caso

Objective: To report a case of hyperparathyroidism secondary to a parathyroid adenoma, presenting a high level of hypercalcemia associated with spontaneous fractures in young pregnant woman. Case report: The patient underwent an emergency cesarean after presenting premature amniorrhexis and tolerated the procedure without complications. The newborn evolved satisfactorily, without symptoms of hypocalcemia. The postpartum woman was then submitted to left lower parathyroidectomy and, in the postoperative period, she developed bone hunger syndrome, despite previous administration of bisphosphonate. There was a progressive resolution of PTH and serum calcium levels, with a consequent improvement in the clinical condition. Conclusion: This report highlights the need and the difficulty regarding the early diagnosis of primary hyperparathyroidism, which is a potentially fatal pathology for the maternal-fetal binomial. Therefore, it is essential to institute proper treatment early, with individualization according to the patient's clinical condition, to minimize the risks of complications and mortality.

Amyotrophic lateral sclerosis: one or multiple causes?

The Amyotrophic lateral sclerosis (ALS) is the most common form of motor neuron disease in the adulthood, and it is characterized by rapid and progressive compromise of the upper and lower motor neurons. The majority of the cases of ALS are classified as sporadic and, until now, a specific cause for these cases still is unknown. To present the different hypotheses on the etiology of ALS. It was carried out a search in the databases: Bireme, Scielo and Pubmed, in the period of 1987 to 2011, using the following keywords: Amyotrophic lateral sclerosis, motor neuron disease, etiology, causes and epidemiology and its similar in Portuguese and Spanish. It did not have consensus as regards the etiology of ALS. Researches demonstrates evidences as regards intoxication by heavy metals, environmental and occupational causes, genetic mutations (superoxide dismutase 1), certain viral infections and the accomplishment of vigorous physical activity for the development of the disease. There is still no consensus regarding the involved factors in the etiology of ALS. In this way, new research about these etiologies are necessary, for a better approach of the patients, promoting preventive programs for the disease and improving the quality of life of the patients

QUELOIDE GIGANTE EM ORELHA: UM RELATO DE CASO

A cicatrização é extremamente importante para a sobrevivência do ser humano, visto que configura um mecanismo de defesa refinado. A contínua restauração do tecido epitelial na pele, permite a regeneração celular e assegura sua integridade morfológica e funcional. O queloide é um fenômeno exclusivamente humano, e ocorre quando há falha na remodelação das cicatrizes provocadas pelo desequilíbrio entre a formação e a degradação de colágeno, assim como modificação na alteração em sua organização espacial, o que gera a cicatriz exuberante. A lesão é elevada, brilhante, pruriginosa e/ou dolorosa, se localiza na derme, com crescimento contínuo, além de ultrapassar os limites da ferida original. O relato aqui apresentado é de um paciente do sexo masculino, 56 anos, que procurou o ambulatório de Cirurgia Geral para exérese de estrutura hipertrófica no lóbulo auricular da orelha direita. O procedimento foi realizado sem nenhuma intercorrência e o paciente teve alta médica no mesmo dia com prescrição de analgésico

Hookah Smoking among Brazilian University Students: An Exploratory Survey on the Prevalence and Perceptions of Addiction and its Harmfulness

Background: This study aimed to determine the prevalence, beliefs, attitudes, and perceptions of hookah use in a population of undergraduate students at a large public university in Brazil. Methods: The sample consisted of 1348 undergraduate students aged over 18-year-old. They completed structured questionnaires on demographic information and close-ended questions on the past and current experiences of smoking hookah. The data underwent descriptive analysis and binary logistic regression.Findings: Finally, 1298 valid survey forms were obtained from printed and digital questionnaires. More than half (53.9%) of participants reported having tried hookah at least once, however, only 10.8% reported they had experienced it within the last 30 days. The majority of the studied population presented acceptable beliefs about the harmfulness and addictive capacity of hookah smoking. However, when comparing the perceptions of those who had smoked and those who had never smoked hookah, and also, the perceptions of users and non-users, significant differences were observed. Students who were users or had already tried hookah showed a tendency to underestimate the deleterious effects of this type of smoking.Conclusion: It could be concluded that hookah smoking was common among Brazilian university students. In addition, preoccupying misperceptions of hookah’s harmfulness and addictive capacity were found. The results showed that the epidemic of hookah smoking, especially among young people, has spread far beyond the Arab world and the Persians. Accordingly, preventive measures must be taken if this population is to be protected from addiction and other serious health problems