Tunable Graphene Single Electron Transistor

We report electronic transport experiments on a graphene single electron transistor. The device consists of a graphene island connected to source and drain electrodes via two narrow graphene constrictions. It is electrostatically tunable by three lateral graphene gates and an additional back gate. The tunneling coupling is a strongly nonmonotonic function of gate voltage indicating the presence of localized states in the barriers. We investigate energy scales for the tunneling gap, the resonances in the constrictions and for the Coulomb blockade resonances. From Coulomb diamond measurements in different device configurations (i.e. barrier configurations) we extract a charging energy of 3.4 meV and estimate a characteristic energy scale for the constriction resonances of 10 meV.Comment: 6 pages and 5 figure

Nonspecific Skin Reactivity in Epidemiological Studies

Os testes cutâneos por prick constituem o método diagnóstico de eleição no estudo da sensibilização alergénica, sendo no entanto influenciados por diversos factores. Não se encontram disponíveis dados sobre a quantificação da reacti-vidade cutânea inespecífica em estudos populacionais pediátricos, incluindo amostras de raças diversas. Objectivo: Avaliar e correlacionar a reactividade cutânea à histamina em crianças de diferentes raças,bem como a possível influência de factores como o sexo e a atopia. Material e Métodos: Englobado no Estudo Português de Doenças Alérgicas na Criança (PAC Study), foram estudadas 1710 crianças em idade escolar (6 a 12 anos), 244 de raça Negra na República de Cabo Verde, 756 Caucasianas na Ilha da Madeira e 710 de raça Chinesa em Macau. A todas as crianças foram efectuados testes cutâneos por prick com aeroalergenos, utilizando como referência positiva um extracto de histamina a 10mg/ml (Merck Allergopharma). Foi efectuada análise comparativa do diâmetro médio da pápula induzida pela histamina

X-ray Nanodiffraction on a Single SiGe Quantum Dot inside a Functioning Field-Effect Transistor

For advanced electronic, optoelectronic, or mechanical nanoscale devices a detailed understanding of their structural properties and in particular the strain state within their active region is of utmost importance. We demonstrate that X-ray nanodiffraction represents an excellent tool to investigate the internal structure of such devices in a nondestructive way by using a focused synchotron X-ray beam with a diameter of 400 nm. We show results on the strain fields in and around a single SiGe island, which serves as stressor for the Si-channel in a fully functioning Si-metal-oxide semiconductor field-effect transistor

Aorto-Enteric Fistula Associated with Aortic Dissection

AbstractPrimary aorto-enteric fistula (PAEF) is usually due to erosion by atherosclerotic aneurysm. We report a case of PAEF secondary to a previously unrecognised focal abdominal aortic dissection. A 66-year-old man was brought to the casualty department with shock and acute-on-chronic back pain. Following resuscitation, he deteriorated further secondary to frank haematemesis. A prompt contrast enhanced CT scan was performed, and aortic dissection with aorto-duodenal fistula was diagnosed and operated on. To our knowledge, there are no previous reports of penetrating, transmural PAEF secondary to abdominal aortic dissection

Valuing in STEM education: Investigating Macau secondary students valuing in mathematics learning

Values are of paramount importance in our society and strengthening values in Science, Technology, Engineering and Mathematics (stem) education has the potential to weave an interactive pattern between stem and various societal structures so that these are continuously and critically examined. It could be argued that what students value in their mathematics learning steer their decisions and actions throughout the learning process. In this context, the What I Find Important (WIFI) Study was designed to identify what students value in mathematics learning. Survey data collected from 612 Grade 8 students were analysed by means of Principal Components Analysis (PCA), showing that Macau students value achievement; relevance; practice; technology; communication and development. In this chapter we analyse and interpret these values in the cultural context of Macau. Differences between Macau students and their peers in the other three greater China regions (i.e., The Chinese Mainland, Hong Kong, and Taiwan) are also discussed