Light Emission in Silicon from Carbon Nanotubes

The use of optics in microelectronic circuits to overcome the limitation of metallic interconnects is more and more considered as a viable solution. Among future silicon compatible materials, carbon nanotubes are promising candidates thanks to their ability to emit, modulate and detect light in the wavelength range of silicon transparency. We report the first integration of carbon nanotubes with silicon waveguides, successfully coupling their emission and absorption properties. A complete study of this coupling between carbon nanotubes and silicon waveguides was carried out, which led to the demonstration of the temperature-independent emission from carbon nanotubes in silicon at a wavelength of 1.3 {\mu}m. This represents the first milestone in the development of photonics based on carbon nanotubes on silicon

Analysis of a narrowband terahertz signal generated by a unitravelling carrier photodiode coupled with a dual-mode semiconductor Fabry–Pérot laser

A narrowband terahertz signal generated by a unitravelling carrier photodiode (UTC-PD) interfaced with a dual-mode Fabry–Pérot laser diode is demonstrated. A beat tone corresponding to the free spectral range is generated on the UTC-PD, and radiated by a transverse-electromagnetic-horn antenna. A terahertz signal at a frequency of 372 GHz, featuring a linewidth of 17 MHz is recorded by a subharmonic mixer coupled to an electrical spectrum analyzer. All components involved in this experiment operate at room temperature. The linewidth and the frequency of the emitted terahertz wave are analyzed, along with their dependency on dc-bias conditions applied to laser diode

NOVAS FORMAS DE ORGANIZAÇÃO NO SETOR PÚBLICO E SUAS CONSEQUÊNCIAS PARA A EDUCAÇÃO À DISTÂNCIA: UMA REVISÃO SISTEMÁTICA DE LITERATURA

O presente estudo de caso pretende realizar uma revisão sistemática da literatura científica sobre o tema da gestão no setor público e educação à distância. Por conseguinte, pretende também entender a trajetória da educação a distância permitindo absorver suas diferentes faces e sua relação com diferentes contextos educacionais, auxiliando na previsão do futuro, diante do contexto educacional que se apresenta o país. Nesse sentido, foram analisados trabalhos de pesquisa (Dissertações) da Universidade Federal de Santa Catarina. O objetivo desta pesquisa consiste em identificar a lacuna teórica sobre o tema de gestão da educação à distância em instituições de ensino superior do setor público. A natureza desta pesquisa é básica, classifica-se como qualitativa, uma vez que não requer o uso de métodos e técnicas estatísticas. O ambiente natural é a fonte direta para coleta de dados e o pesquisador é o instrumento-chave. É descritiva. O processo e seu significado são os focos principais de abordagem. Quanto aos fins, possui caráter descritivo. Quanto aos meios, será utilizada a Pesquisa Bibliográfica. A amostra será composta por seis dissertações na área de Educação à Distância dos cursos de Mestrado em Administração e Administração Universitária da Universidade Federal de Santa Catarina. Os instrumentos de coleta de dados a serem utilizados serão referências bibliográficas e pesquisa documental como fonte de dados primários. Paralelamente neste artigo serão revisados aspectos sobre EAD desde um histórico mundial e brasileiro, as diferentes definições sobre EAD apresentadas, assim como os aspectos positivos e negativos destacados nos trabalhos analisados. Por fim, será apresentada uma discussão sobre o cenário atual e perspectivas futuras da EAD no Brasil

Gas-solid carbonation as a possible source of carbonates in cold planetary environments

International audienceCarbonates are abundant sedimentary minerals at the surface and sub-surface of the Earth and they have been proposed as tracers of liquid water in extraterrestrial environments. Their formation mechanism is since generally associated with aqueous alteration processes. Recently, carbonate minerals have been discovered on Mars' surface by different orbital or rover missions. In particular, the phoenix mission has measured from 1 to 5% of calcium carbonate (calcite type) within the soil (Smith P.H. et al., 2009). These occurrences have been reported in area were the relative humidity is significantly high (Boynton et al., 2009). The small concentration of carbonates suggests an alternative process on mineral grain surfaces (as suggested by Shaheen et al., 2010) than carbonation in aqueous conditions. Such an observation could rather point toward a possible formation mechanism by dust-gas reaction under current Martian conditions. To understand the mechanism of carbonate formation under conditions relevant to current Martian atmosphere and surface, we designed an experimental setup consisting of an infrared microscope coupled to a cryogenic reaction cell (IR-CryoCell setup). Three different mineral precursors of carbonates (Ca and Mg hydroxides, and a hydrated Ca silicate formed from Ca2SiO4), low temperature (from -10 to +30°C), and reduced CO2 pressure (from 100 to 2000 mbar) were utilized to investigate the mechanism of gas-solid carbonation at mineral surfaces. These mineral materials are crucial precursors to form Ca and Mg carbonates in humid environments (0 < relative humidity < 100%) at dust-CO2 or dust-water ice-CO2 interfaces. Our results reveal a significant and fast carbonation process for Ca hydroxide and hydrated Ca silicate. Conversely, only a moderate carbonation is observed for the Mg hydroxide. These results suggest that gas-solid carbonation process or carbonate formation at the dust-water ice-CO2 interfaces could be a currently active Mars' surface process. To the best of our knowledge, we report for the first time that calcium carbonate can be formed at a negative temperature (-10°C) via gas-solid carbonation of Ca hydroxide. We note that the carbonation process at low temperature (<0°C) described in the present study could also have important implications on the dust-water ice-CO2 interactions in cold terrestrial environments (e.g. Antarctic)

Metabolic Profile And Spontaneous Physical Activity Modulation Under Short-term Food Restriction In Young Rats.

The aim of this study was to investigate the effects of short-term food restriction (6-weeks) on metabolic profile and spontaneous physical activity (SPA) of young male Wistar rats. METHODS Thirty rats had their baseline SPA measured at 21 days-old and were separated into two groups at 28 days-old: Control (CG) and 50% of food restriction (FR). The food restriction protocol lasted six weeks, being the SPA measured weekly by a gravimetric apparatus. At the end of the experiment, biochemical analyses were performed in serum and tissue samples with statistical significance set at 5%. RESULTS FR showed less SPA than CG, as occurred for body mass, water intake, adipose tissue and liver, heart and soleus glycogen, serum glucose, total protein, triglycerides and total cholesterol (P&lt;0.05). CONCLUSION Data set demonstrates that low substrate stores signaled to decrease spontaneous physical activity to save energy.23especia

High Security Laboratory - Network Telescope Infrastructure Upgrade

As part of the High Security Laboratory at INRIA Nancy Grand Est inaugurated in July 2010, we have been running and maintaining a network telescope for more than 2 years. Many updates and upgrades of the different components have been made during this period, as well as the apparition of new threats and vulnerabilities, motivating an upgrade of the existing infrastructure to maintain it up-to-date with the current security issues. This report is a follow up of the previous report written in May 2008 describing the specification and deployment of the initial infrastructure. In this report, we present the upgrade performed during the second half of the year 2010, after the inauguration and moving of the platform

Melatonin has an ergogenic effect but does not prevent inflammation and damage in exhaustive exercise

It is well documented that exhaustive physical exercise leads to inflammation and skeletal muscle tissue damage. With this in mind, melatonin has been acutely administered before physical exercise; nevertheless, the use of melatonin as an ergogenic agent to prevent tissue inflammation and damage remains uncertain. We evaluated the effects of melatonin on swimming performance, muscle inflammation and damage and several physiological parameters after exhaustive exercise at anaerobic threshold intensity (iLAn) performed during light or dark circadian periods. The iLAn was individually determined and two days later, the animals performed an exhaustive exercise bout at iLAn 30 minutes after melatonin administration. The exercise promoted muscle inflammation and damage, mainly during the dark period and the exogenous melatonin promoted a high ergogenic effect. The expressive ergogenic effect of melatonin leads to longer periods of muscle contraction, which superimposes a possible melatonin protective effect on the tissue damage and inflammation5CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP305650/2009- 22009/08535-5; 2011/13226-1; 2012/20501-

O processo de formação e constituição do representante membro de Comitês de Bacia hidrográfica: um olhar sobre a experiência participativa/ The process of formation and constitution of the representative member of Basin Committees River: a look at the participatory experience

Neste trabalho, refletimos sobre o processo de formação dos membros representantes de Comitês de bacia hidrográfica no Brasil. A análise foi realizada por meio leitura de Bourdieu, Berger e Luckmann, entre outros autores, e permeia questões referentes a experiência participativa, formação e constituição do representante, enquanto membro de um organismo de bacia. Caracteriza-se por uma abordagem interpretativa e exploratório desenvolvido através da análise dos questionários de pesquisa com base em uma amostra de 35%, de um universo de 11.197 representantes, entre titulares e suplentes, que fazem parte de 205 dos 210 comitês estaduais de bacias hidrográficas no Brasil.

Defect formation during chlorine-based dry etching and their effects on the electronic and structural properties of InP/InAsP quantum wells

Producción CientíficaThe general objective is the investigation of the defects formed by dry etching tools such as those involved in the fabrication of photonic devices with III–V semiconductors. Emphasis is put on plasma exposures with chlorine-based chemistries. In addition to identifying these defects and describing their effects on the electro-optic and structural properties, the long-term target would be to predict the impact on the parameters of importance for photonic devices, and possibly include these predictions in their design. The work is first centered on explaining the experimental methodology. This methodology starts with the design and growth of a quantum well structure on indium phosphide, including ternary indium arsenide/phosphide quantum wells with graded arsenic/phosphor composition. These samples have then been characterized by luminescence methods (photo- and cathodoluminescence), high-resolution transmission electron microscopy, and secondary ion mass spectrometry. As one of the parameters of importance in this study, the authors have also included the doping level. The samples have been exposed to the etching plasmas for “short” durations that do not remove completely the quantum wells, but change their optical signature. No masking layer with lithographic features was involved as this work is purely oriented to study the interaction between the plasma and the samples. A significant difference in the luminescence spectra of the as-grown undoped and doped samples is observed. A mechanism describing the effect of the built-in electric field appearing as a consequence of the doping profile is proposed. This mechanism involves quantum confined Stark effect and electric-field induced carrier escape from the quantum wells. In the following part, the effects of exposure to various chlorine-based plasmas were explored. Differences are again observed between the undoped and doped samples, especially for chemistries containing silicon tetrachloride. Secondary ion mass spectrometry indicates penetration of chlorine in the structures. Transmission electron microscopy is used to characterize the quantum well structure before and after plasma bombardment. By examining carefully the luminescence spectral properties, the authors could demonstrate the influence of the etching plasmas on the built-in electric field (in the case of doped samples), and relate it to some ionic species penetrating the structures. Etching plasmas involving both chlorine and nitrogen have also been studied. The etching rate for these chemistries is much slower than for some of the silicon tetrachloride based chemistries. Their effects on the samples are also very different, showing much reduced effect on the built-in electric field (for the doped samples), but significant blue-shifts of the luminescence peaks that the authors attributed to the penetration of nitrogen in the structures. Nitrogen, in interstitial locations, induces mechanical compressive stress that accounts for the blue-shifts. Finally, from the comparison between secondary ion mass spectrometry and luminescence spectra, the authors suggest some elements for a general mechanism involved in the etching by chloride-chemistries, in which a competition takes place between the species at the surface, active for the etching mechanism, and the species that penetrate the structure, lost for the etching process, but relevant in terms of impact on the electro-optic and structural features of the exposed materials.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA302U13