Sputtered W–N diffusion barriers

The thermal stability of reactively sputtered tungsten–nitrogen alloy thin films is investigated for the application as diffusion barriers in silicon contact metallizations. The composition of W–N barriers is varied over a wide range including pure W. Aluminum, gold, and silver are used as low resistivity overlayers. Metallurgical interactions at temperatures ranging from 500 to 900 °C are studied. Incorporating nitrogen into tungsten advantageously stabilizes all three systems. The overall failure takes place rapidly above critical temperatures that depend on both the metal overlayer and the microstructure of the barrier. In some cases, W–N alloys can effectively prevent interdiffusion at temperatures as high as 800 °C for 30 min

Laser annealing of silicon on sapphire

Silicon-implanted silicon-on-sapphire wafers have been annealed by 50-ns pulses from a Q-switched Nd : YAG laser. The samples have been analyzed by channeling and by omega-scan x-ray double diffraction. After irradiation with pulses of a fluence of about 5 J cm^–2 the crystalline quality of the silicon layer is found to be better than in the as-grown state

Mal/SRF Is Dispensable for Cell Proliferation in Drosophila

The Mal/SRF transcription factor is regulated by the level of G-actin in cells and has important roles in cell migration and other actin-dependent processes in Drosophila. A recent report suggests that Mal/SRF and an upstream regulator, Pico, are required for cell proliferation and tissue growth in Drosophila. I find otherwise. Mutation of Mal or SRF does not affect cell proliferation in the fly wing. Furthermore, I cannot reproduce the reported effects of Pico RNAi or Pico overexpression on body size. Nevertheless, I can confirm that overexpression of Pico or Mal causes tissue overgrowth specifically in the fly wing - where SRF is most highly expressed. My results indicate that Mal/SRF can promote tissue growth when abnormally active, but is not normally required for tissue growth during development

PERSPECTIVAS DO ENSINO-APRENDIZAGEM DE LÍNGUAS ESTRANGEIRAS

A educação cumpre uma função social. Assim, em limiar de um século pragmático, dinâmico e volátil, a escola, bem como a docência, passa a ter novas exigências sociais. Nesse aspecto, para que os sujeitos tenham um concreto engajamento no mundo social, faz-se necessário não apenas o desenvolvimento de habilidades linguísticas na língua vernácula, mas também em uma língua estrangeira. Em vista disso, este trabalho concerniu ao esforço de investigação às principais contribuições de uma base epistemológica especializada acerca das perspectivas do ensino-aprendizagem de línguas estrangeiras. Da natureza metodológica do trabalho, a pesquisa foi exploratória quanto aos objetivos, e de bibliografia em relação às fontes de informação, sendo a pesquisa bibliográfica amparada pela técnica da documentação indireta, o principal procedimento de coleta de dados. Já com os dados, foram analisados qualitativamente em uma perspectiva crítico-reflexiva, dos quais se obtiveram intrigantes implicações. Primeira, a relevância da aprendizagem, domínio, competência e empenho linguístico-discursivos em uma língua estrangeira no limiar de uma era em que se intensificam as relações internacionais, o progresso tecno-científico, a globalização. Segunda, os fatores que (in)viabilizam o efetivo processo de ensino-aprendizagem de línguas estrangeiras. Destarte, inferindo, existem lacunas e paradigmas educacionais. Por conseguinte, o processo de ensino-aprendizagem de línguas estrangeiras está falho. Um dos primeiros passos à reversão desse panorama é compreender a língua como um fenômeno essencialmente oral, a heterogeneidade da discência, o protagonismo na aprendizagem, enfim, ter a prática pedagógica consolidada na aplicabilidade, utilidade, significação real dos conteúdos e atividades para a aprendizagem discente, e, significativamente, no lúdico.    Palavras-chave: Educação. Ensino-aprendizagem. Língua estrangeira. Perspectivas.

Examination of Fluconazole-Induced Alopecia in an Animal Model and Human Cohort.

Fluconazole-induced alopecia is a significant problem for patients receiving long-term therapy. We evaluated the hair cycle changes of fluconazole in a rat model and investigated potential molecular mechanisms. Plasma and tissue levels of retinoic acid were not found to be causal. Human patients with alopecia attributed to fluconazole also underwent detailed assessment and in both our murine model and human cohort fluconazole induced telogen effluvium. Future work further examining the mechanism of fluconazole-induced alopecia should be undertaken

Phase-coherence threshold and vortex-glass state in diluted Josephson-junction arrays in a magnetic field

We study numerically the interplay of phase coherence and vortex-glass state in two-dimensional Josephson-junction arrays with average rational values of flux quantum per plaquette $f$ and random dilution of junctions. For $f=1/2$, we find evidence of a phase coherence threshold value $x_s$, below the percolation concentration of diluted junctions $x_p$, where the superconducting transition vanishes. For $x_s < x < x_p$ the array behaves as a zero-temperature vortex glass with nonzero linear resistance at finite temperatures. The zero-temperature critical currents are insensitive to variations in $f$ in the vortex glass region while they are strongly $f$ dependent in the phase coherent region.Comment: 6 pages, 4 figures, to appear in Phys. Rev.

Variable response in alpine tree-ring stable isotopes following volcanic eruptions in the tropics and iceland

The importance of the stable isotopes in tree rings for the study of the climate variations caused by volcanic eruptions is still unclear. We studied &delta;18O, &delta;D, &delta;13C stable isotopes of larch and cembran pine cellulose around four major eruptions with annual resolution, along with a superposed epoch analysis of 34 eruptions with 5-year resolution. Initial analysis of the tropical Tambora (1815 CE) and Samalas (1257 CE) eruptions showed a post-eruption decrease in &delta;18O values attributed to post-volcanic cooling and increased summer precipitation in Southern Europe, as documented by observations and climate simulations. The post-volcanic cooling was captured by the &delta;D of speleothem fluid inclusion. The &delta;18O decrease was also observed in the analysis of 34 major tropical eruptions over the last 2000 years. In contrast, the eruptions of c. 750, 756, and 764 CE attributed to Icelandic volcanoes left no significant responses in the cellulose isotopes. Further analysis of all major Icelandic eruptions in the last 2000 years showed no consistent isotopic fingerprints, with the exception of lower post-volcanic &delta;13C values in larch. In summary, the &delta;18O values of cellulose can provide relevant information on climatic and hydroclimatic variations following major tropical volcanic eruptions, even when using the 5-year resolution wood samples of the Alpine Tree-Ring Isotope Record database