Emittance sharing and exchange driven by linear betatron coupling in circular accelerators

The influence of linear betatron coupling due to constant-in-time skew quadrupolar fields on the transverse emittances is discussed using both a simplified model of a smooth circular accelerator and a more realistic strong-focusing lattice with localized sources of coupling (thin lens). New formulas for the coupled transverse emittances are derived that include the initial emittances, the coupling strengths, and the tune distance from the resonance. By using the more powerful Lie algebra and the resonance driving terms formalism, equivalent formulas are derived that provide a better understanding of some counterintuitive effects, otherwise not understandable in the smooth approximation. The new formulas have been tested both numerically and experimentally by using data of the CERN Proton Synchrotron showing a remarkable agreement

Body dysmorphic disorder in patients with acne: treatment challenges

Body dysmorphic disorder (BDD) is defined as a constant preoccupation with one or more non-existent or slight defects or flaws in the physical appearance, often resulting in repetitive behaviours like mirror checking and camouflaging. The prevalence is around 2% in the general population with up to 10% in dermatology patients. The prevalence of BDD in patients with acne ranges between 9% and 15%. BDD is associated with considerable psychosocial deterioration, poor quality of life, and development of comorbid mental health disorders, including obsessive compulsive disorder, depression, social anxiety and alcohol or illicit drug use. Such patients suffer tremendously and are at high risk of suicide. The rate of suicidal ideation reaches 79.5%. Of this number, nearly 27.6% make failed suicidal attempts each year and 0.3% of these attempts are successful..

Seven-branes and Supersymmetry

We re-investigate the construction of half-supersymmetric 7-brane solutions of IIB supergravity. Our method is based on the requirement of having globally well-defined Killing spinors and the inclusion of SL(2,Z)-invariant source terms. In addition to the well-known solutions going back to Greene, Shapere, Vafa and Yau we find new supersymmetric configurations, containing objects whose monodromies are not related to the monodromy of a D7-brane by an SL(2,Z) transformation.Comment: 31 pages, 3 figure

The discrimination capabilities of Micromegas detectors at low energy

The latest generation of Micromegas detectors show a good energy resolution, spatial resolution and low threshold, which make them idoneous in low energy applications. Two micromegas detectors have been built for dark matter experiments: CAST, which uses a dipole magnet to convert axion into detectable x-ray photons, and MIMAC, which aims to reconstruct the tracks of low energy nuclear recoils in a mixture of CF4 and CHF3. These readouts have been respectively built with the microbulk and bulk techniques, which show different gain, electron transmission and energy resolutions. The detectors and the operation conditions will be described in detail as well as their discrimination capabilities for low energy photons will be discussed.Comment: To be published in the proceedings of the TIPP2011 conference (Physics Procedia

IIA Ten-forms and the Gauge Algebras of Maximal Supergravity Theories

We show that IIA supergravity can be extended with two independent 10-form potentials. These give rise to a single BPS IIA 9-brane. We investigate the bosonic gauge algebra of both IIA and IIB supergravity in the presence of 10-form potentials and point out an intriguing relation with the symmetry algebra $E_{11}$, which has been conjectured to be the underlying symmetry of string theory/M-theory.Comment: 18 pages, section on IIA 9-branes added, references added; version to be publishe

A study of temperature-related non-linearity at the metal-silicon interface

In this paper, we investigate the temperature dependencies of metal-semiconductor interfaces in an effort to better reproduce the current-voltage-temperature (IVT) characteristics of any Schottky diode, regardless of homogeneity. Four silicon Schottky diodes were fabricated for this work, each displaying different degrees of inhomogeneity; a relatively homogeneous NiV/Si diode, a Ti/Si and Cr/Si diode with double bumps at only the lowest temperatures, and a Nb/Si diode displaying extensive non-linearity. The 77–300 K IVT responses are modelled using a semi-automated implementation of Tung's electron transport model, and each of the diodes are well reproduced. However, in achieving this, it is revealed that each of the three key fitting parameters within the model display a significant temperature dependency. In analysing these dependencies, we reveal how a rise in thermal energy “activates” exponentially more interfacial patches, the activation rate being dependent on the carrier concentration at the patch saddle point (the patch's maximum barrier height), which in turn is linked to the relative homogeneity of each diode. Finally, in a review of Tung's model, problems in the divergence of the current paths at low temperature are explained to be inherent due to the simplification of an interface that will contain competing defects and inhomogeneities

Pontine and Extrapontine Myelinolysis

Introdução: A mielinólise define-se como uma doença desmielinizante aguda, associada a um quadro clínico de tetraplegia flácida e a incapacidade na fala e na deglutição. A patogenia em geral está associada a perturbações electrolíticas, particularmente hiponatrémia profunda e sua rápida correcção. A confirmação imagiológica do diagnóstico pode ser feita recorrendo à Ressonância Magnética Nuclear. Objectivo: Os autores fazem a descrição do caso clínico, evidenciando a sua evolução e programa de reabilitação instituído, realçando os ganhos da funcionalidade. São descritas também as intercorrências clínicas relevantes no atraso do diagnóstico. Caso clínico: Apresenta-se uma doente com antecedentes psiquiátricos e polidipsia, internada na sequência de um quadro convulsivo resistente à medicação, tendo sido identificada hiponatrémia e feita a sua correcção. Após a correcção a doente desenvolveu um quadro de tetraplegia e hipotonia generalizada, tendo realizado uma Ressonância Magnética compatível com o diagnóstico de mielinólise centropôntica e extrapôntica