Design and analysis of silicon antiresonant reflecting opticalwaveguides for evanescent field sensor

Silicon based antiresonant reflecting optical waveguides (ARROW's) have been designed in order to obtain a high sensitive optical transducer for sensing applications. The designed sensor has an integrated Mach-Zehnder interferometer configuration. The optical waveguides that form its structure have to verify two conditions: monomode behavior and high surface sensitivity. In this paper, we present a theoretical modeling of the propagation characteristics and surface sensitivity of the ARROW structure     

Optical and electrical characterization of GaN layers grown on silicon and sapphire substrates

Characterization of the structural, optical and electrical properties of GaN layers grown by two epitaxial techniques (ECR-MBE and MOCVD) using different substrates (vicinal Si111 and sapphire) has been performed. The quality of the samples grown by MOCVD seems to be influenced by the nitrogen source used for the growth. Unintentionally doped MBE samples with n-type concentrations around 10¹⁸ cm⁻³ and Hall mobility of 15 cm² (V s)⁻¹ were studied. GaN films doped with Mg and grown using AlN buffer layers have also been analyzed to study the influence of the thickness of the buffer layer on the optical properties of the GaN epilayer. In the samples with low Mg doping, a thin AlN buffer layer improved the optical quality of the film. In general, all the MBE samples doped with Mg were highly resistive, probably due to a low activation or high ionization energy of the Mg acceptors. Technological issues related to the formation of ohmic contacts on GaN layers are also presented.     

Epinephrine-induced reduction in insulin receptor mRNA level and stability in U-937 human promonocytic cells

Abscess of the psoas muscle (PA) is every more frequently observed in recent years. The PA diagnosed in the authors' center over a period of 91 months are presented, analyzing the main clinical features, microbiologic causal agents, risk factors, treatment and the differences between primary and secondary PA. A total of 19 cases of which 14 were secondary PA (73.7%) and 5 primary PA (26.3%) were diagnosed. The main foci of infection of the former were the bone and the genitourinary tract, with intestinal infection being rare. The most frequent clinical data were lumbar pain with possible irradiation to the lower limb, fever, and leucocytosis with neutrophilia. Gram negative and enteric anaerobes were the bacteria most often identified, followed by Staphylococcus aureus and Mycobacterium tuberculosis. In a high percentage of patients (57.8%) a history of immunodeficiency was reported. In regard to treatment, surgical drainage was performed in 5 cases (26.3%), while ten cases (52.6%) were treated by DPCT. Four patients (21%) were exclusively treated with antibiotics. Recurrence was observed in three cases (15.3%) of the DPCT group requiring new drainage. Of all the cases, 18 were cured while one death occurred, being attributed to the underlying tumoral disease of advanced stage. The authors believe DPCT to be a good therapeutic option in both primary and secondary PA, thereby avoiding the risks of major surgery. In the cases with no underlying immunodeficiency the existence of secondary PA should be discarded as occurred in 7 out of 8 cases with no history of immunodeficiency in this series of patients.     

Fast method for multielemental analysis of plants and discrimination according to the anatomical part by total reflection X-ray fluorescence spectrometry

Fast and reliable analytical methodologies are required for quality control of plants in order to assure human health. Ultrasound-assisted extraction in combination with total reflection X-ray fluorescence is proposed as a fast and simple method for multielemental analysis of plants on a routine basis. For this purpose, five certified reference materials have been analysed for the determination of P, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn and Pb. Different extractant media (acids and oxidants) were tried. A mixture of diluted HNO₃ + HCl + HF, was selected as the best option for the achievement of complete extractions. Accurate and precise results can be reached in most cases along with a high sample throughput. Different plants (i.e., herbs, spices and medicinal plants) were analysed. Linear discriminant analysis together with the elemental concentrations allowed the differentiation of commercial preparations corresponding to flower, fruit and leaf.     

Optical characterization of [111]B InGaAs layers

Strain assessment of [111]B InGaAs/GaAs layers, of several compositions and variable thicknesses, has been performed by photoluminescence and Raman spectroscopies. Both the gap energy and GaAs-like LO frequency undergo a blue shift proportional to the residual strain, which can be thus determined. The critical layer thickness for [111]B orientation is found to be three times larger than for [001] layers grown simultaneously. In addition, two kinds of inhomogeneities in the relaxation are found: strain domains, demonstrated by the spectral and spatial resolution of photoluminescence excitation, micro-photoluminescence and micro-Raman experiments; and a change in the strain release with layer depth, obtained by Raman at different excitation energies.     

GaN-Based Solar-Ultraviolet Detection Instrument

We report on the fabrication of a solar-UV monitoring system that uses GaN-based photodetectors. GaN photoconductors, p-n junction photodiodes, and Schottky barrier photodiodes have been fabricated and characterized as UV sensors. The best performances are obtained in Schottky photodiodes, which show a linear response, a flat responsivity of 100 mA/W, a visible rejection ratio higher than 10(3), and a noise-equivalent power of 1 nW/Hz(-1/2). Preliminary data on Al(x)Ga(1-x)N (x = 0.15, 0.22) detectors are also presented. Using GaN Schottky diodes, we fabricate and evaluate a complete solar-UV detection head.     

Personal contact from friends to increase mammography usage

To increase the use of mammography among women 40 years of age and older, the American Cancer Society (ACS) designed a telephone intervention strategy (the "Tell A Friend" program) that relied on ACS volunteers. During a half-day training session, each volunteer provided a list of 10 women she was willing to contact over a 6-month period and encourage to have a mammogram. Each list was randomized, and five names were returned to each volunteer for inclusion in the intervention. The other women served as controls and were not contacted by the volunteers. All women were subsequently interviewed at the end of the intervention period. Forty-nine percent of the women in the intervention group (n = 289) had received their most recent mammogram since the start of the intervention period, whereas 34% of control women (n = 305) received mammograms during the same time period (p < or = .001, rate ratio = 1.4, 95% confidence interval = 1.2, 1.7). The effectiveness of the intervention remained after controlling for demographic characteristics. The strategy was effective for both black and white women of all ages, but principally among women with annual household incomes of less than $40,000. We conclude that a telephone intervention strategy of personal contacts between acquainted women can significantly increase mammography use, particularly among women with low-to-moderate income.     

Age-induced hypertrophy of astrocytes in rat supraoptic nucleus: a cytological, morphometric, and immunocytochemical study

BACKGROUND: In the adult rat, neuron-astroglia interactions in the supraoptic nucleus (SON) are characterized by the structural and functional plasticity of astrocytes in response to several physiological and experimental conditions. This study has analyzed the plasticity of the supraoptic nucleus astrocytes in response to the age-induced changes in neuronal activity. METHODS: The study was performed in 5-, 12-, 18- and 24-month-old rats. The cytology and organization of astrocytes in the SON were examined using glial fibrillary acidic and vimentin immunocytochemistry and ultrastructural and morphometric analysis. RESULTS: No significant age-related variations in the total number of neurons and astrocytes in the SON were detected, although a few degenerating neurons were found in old rats. An age-dependent increase in GFAP immunoreactivity was observed at the ventral glial lamina, perivascularly and between neuronal perikarya. Vimentin overexpression was also detected in ventral lamina astrocytes with advancing age. At the cell nucleus level, we observed an age-associated increase in nuclear size and in the number of coiled bodies, nuclear bodies, and "cleared" nucleoplasmic areas, as well as changes in the nucleolar organization. At the cytoplasmic level, characteristic ultrastructural features in astrocytes of old rats were the hypertrophy of intermediate filament bundles and the formation of an extensive network of Golgi stacks interlinked by tubulovesicular elements. Glial filaments were often associated with the nuclear envelope and polyribosomes. CONCLUSIONS: The increased GFAP and vimentin immunoreactivity and the morphometric and cytological changes in rat SON astrocytes may reflect a sustained upregulation of cellular activity with age, resulting in hypertrophy of glial perikarya and cell processes. Several factors that are known to influence the expression of the astrocytic phenotype, such as signals produced by degenerating neurons and activated microglia, as well as variations in neuronal activity are considered possible causes of the age-associated changes in SON astrocytes.     

Understanding Indirect Causal Relationships in Node‐Link Graphs

To find correlations and cause and effect relationships in multivariate data sets is central in many data analysis problems. A common way of representing causal relations among variables is to use node‐link diagrams, where nodes depict variables and edges show relationships between them. When performing a causal analysis, analysts may be biased by the position of collected evidences, especially when they are at the top of a list. This is of crucial importance since finding a root cause or a derived effect, and searching for causal chains of inferences are essential analytic tasks when investigating causal relationships. In this paper, we examine whether sequential ordering influences understanding of indirect causal relationships and whether it improves readability of multi‐attribute causal diagrams. Moreover, we see how people reason to identify a root cause or a derived effect. The results of our design study show that sequential ordering does not play a crucial role when analyzing causal relationships, but many connections from/to a variable and higher strength/certainty values may influence the process of finding a root cause and a derived effect.