Amorphous metallic films in silicon metallization systems

The general objective was to determine the potential of amorphous metallic thin films as a means of improving the stability of metallic contacts to a silicon substrate. The specific objective pursued was to determine the role of nitrogen in the formation and the resulting properties of amorphous thin-film diffusion barriers. Amorphous metallic films are attractive as diffusion barriers because of the low atomic diffusivity in these materials. Previous investigations revealed that in meeting this condition alone, good diffusion barriers are not necessarily obtained, because amorphous films can react with an adjacent medium (e.g., Si, Al) before they recrystallize. In the case of a silicon single-crystalline substrate, correlation exists between the temperature at which an amorphous metallic binary thin film reacts and the temperatures at which the films made of the same two metallic elements react individually. Amorphous binary films made of Zr and W were investigated. Both react with Si individually only at elevated temperatures. It was confirmed that such films react with Si only above 700 C when annealed in vacuum for 30 min. Amorphous W-N films were also investigated. They are more stable as barriers between Al and Si than polycrystalline W. Nitrogen effectively prevents the W-Al reaction that sets in at 500 C with polycrystalline W

THE EFFECTS OF HOUSING PRICES, WAGES, AND COMMUTING TIME ON JOINT RESIDENTIAL AND JOB LOCATION CHOICES

A utility maximizing framework is used to model how wages, housing prices, and commuting time affect joint decisions of where to live and where to work. The implied multinomial logit model yields plausible estimates of the role of economic variables on joint residence/job location choices.Labor and Human Capital,

Inactive alleles of cytochrome P450 2C19 may be positively selected in human evolution Genome evolution and evolutionary systems biology

© 2014 Janha et al.; licensee BioMed Central Ltd.Background: Cytochrome P450 CYP2C19 metabolizes a wide range of pharmacologically active substances and a relatively small number of naturally occurring environmental toxins. Poor activity alleles of CYP2C19 are very frequent worldwide, particularly in Asia, raising the possibility that reduced metabolism could be advantageous in some circumstances. The evolutionary selective forces acting on this gene have not previously been investigated. We analyzed CYP2C19 genetic markers from 127 Gambians and on 120 chromosomes from Yoruba, Europeans and Asians (Japanese + Han Chinese) in the Hapmap database. Haplotype breakdown was explored using bifurcation plots and relative extended haplotype homozygosity (REHH). Allele frequency differentiation across populations was estimated using the fixation index (FST) and haplotype diversity with coalescent models. Results: Bifurcation plots suggested conservation of alleles conferring slow metabolism (CYP2C19∗2 and ∗3). REHH was high around CYP2C19∗2 in Yoruba (REHH 8.3, at 133.3 kb from the core) and to a lesser extent in Europeans (3.5, at 37.7 kb) and Asians (2.8, at -29.7 kb). FST at the CYP2C19 locus was low overall (0.098). CYP2C19∗3 was an FST outlier in Asians (0.293), CYP2C19 haplotype diversity ST is low at the CYP2C19 locus, suggesting balancing selection overall. The biological factors responsible for these selective pressures are currently unknown. One possible explanation is that early humans were exposed to a ubiquitous novel toxin activated by CYP2C19. The genetic adaptation took place within the last 10,000 years which coincides with the development of systematic agricultural practices.This work was supported by the Medical Research Council Unit The Gambia and the European and Developing Countries Clinical Trials Partnership [grant number CG_ta_05_40204_018]

Reactively sputtered RuO2 diffusion barriers

The thermal stability of reactively sputtered RuO2 films is investigated from the point of view of their application as diffusion barriers in silicon contact metallizations with an Al overlayer. Backscattering spectra of Si/RuO2/Al samples and electrical measurements on shallow junction diodes with Si/TiSi2.3/RuO2/Al contacts both show that RuO2 films are effective diffusion barriers between Al and Si for 30-min annealing at temperatures as high as 600°C

Guidelines for the treatment of gout: a Swiss perspective.

Gout is a common condition and its management is suboptimal. A number of guidelines on the management of gout have been published in the last decade by professional societies with the aim of informing the physician of the recommended therapeutic strategies and the treatment options. We have tried to synthesize the current recommendations and to highlight some challenges that still need to be resolved in clinical practice in Switzerland

WxN1–x alloys as diffusion barriers between Al and Si

Reactively sputtered tungsten nitride (WxN1–x) layers are investigated as diffusion barriers between Al overlayers and Si shallow n + -p junctions. Both amorphous W80 N20 and polycrystalline W60 N40 films were found to be very effective in preserving the integrity of the n + -p diodes for 30-min vacuum annealing up to 575 °C. Diode failure at higher temperatures is caused by localized penetration of Al into through the WxN1–x barriers. The effectiveness of the barrier decreases for polycrystalline W90 N10 and is worse for pure W

Economic analysis of locust bean processing and marketing in Iwo local government, Osun state.

This study was designed to estimate the economic analysis of locust bean processing and marketing in Iwo Local Government Area of Osun State, Nigeria. Primary data was used and purposive sampling technique was adopted to select the respondents used for the study. A total number of 60 respondents were interviewed. The data collected were analyzed using inferential statistical tool such as regression analysis. Budgetary analysis technique was also used to analyze the profitability of locust bean processing and marketing in the study area. Majority (78.3%) of the processors and marketers were making profit; 95.0% operate above break even point while 3.3% operate at break even point this indicates that they neither gain nor loss. The regression analysis result shows that quantity processed and years of experience in processing were significant at 1% and 10% respectively, while stall rent was significant at 5%. F-test also explained that independent variables are jointly significant at 1% probability level with an adjusted R2 of 79.8%. It was therefore concluded that locust bean enterprise is profitable and attention should be focused on boosting quantity of locust bean seeds available for processing and the revenue from its’ sales through cultivation and planting of more locust bean trees.Keywords: Locust bean, processing, marketing, Iwo, Budgetary techniques, Regression analysis

Systems Engineering Technical Authority: A Path to Mission Success

The systems engineering of space missions to study planet Earth has been an important focus of the National Aeronautics and Space Administration (NASA) since its inception. But all space missions are becoming increasingly complex and this fact, reinforced by some major mishaps, has caused NASA to reevaluate their approach to achieving safety and mission success. A new approach ensures that there are adequate checks and balances in place to maximize the probability of safety and mission success. To this end the agency created the concept of Technical Authority which identifies a key individual accountable and responsible for the technical integrity of a flight mission as well as a project-independent reporting path. At the Goddard Space Flight Center (GSFC) this responsibility ultimately begins with the Mission Systems Engineer (MSE) for each satellite mission. This paper discusses the Technical Authority process and then describes some unique steps that are being taken at the GSFC to support these MSEs in meeting their responsibilities

Prevalence of Antibiotic-Resistant Strains of Escherichia coli in Drinking Water Samples from Mowe Metropolis, Ogun State, Nigeria

A measured Escherichia coli level in drinking water is perhaps the most popular means of determining human health risks globally. Water samples from wells, boreholes and sachet water, the 3 predominant sources of drinking water in the study area were evaluated for the presence of bacteria, particularly E coli. Bacteria isolation was done using standard microbiological procedures while identification of isolates was done using cultural, morphological and biochemical characteristics. Enumeration of standard plate count was done by spread plate method on serially diluted water samples. The prevalence of E coli in the water samples and the activities of cefoxitin, fusidic acid, meticillin, penicillin and vancomycin against the E coli isolates and the susceptibility testing data were obtained using Kirby Bauer method. A total of six bacteria species Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Klebsiella pneumonia, Staphylococcus aureus, Enterobacter aerogenes were isolated from water samples obtained from borehole, well and sachet water samples in the study area. The mean bacteria counts ranged between 3.74 x 104 to 1.65 x 102 CFU/ml for well and borehole water and 0.81 to 5.1 x 102 CFU/ml for sachet water samples. Out of the 6 E coli strains representing 27.2% of the isolated bacteria species; two, representing 33.3% of the strainsshowed moderate to high resistance against meticillin. These findings are expected to motivate public health stakeholders in the study location to attempt reducing the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects.Key words: antibiotic resistance, meticillin, water quality, E. coli Un niveau d'Escherichia coli mesurées dans l'eau potable est peut-être le moyen le plus populaire de la détermination des risques pour la santé humaine à l'échelle mondiale. Des échantillons d'eau de puits, de forages et de l'eau de sachet, les trois principales sources d’eau potable dans la zone d'étude ont été évalués pour la présence de bactéries, en particulier E. coli. L'isolement de bactéries a été effectué en utilisant des procédures microbiologiques standard tandis que l'identification des isolats a été effectuée à l'aide des caractéristiques culturelles, morphologiques et biochimiques. Énumération de nombre de plaque standard a été effectuée par la méthode de la plaque de propagation sur des échantillons d'eau dilués en série. La prévalence de E. coli dans les échantillons d'eau et les activités de la céfoxitine, l'acide fusidique, la méticilline, la pénicilline etde la vancomycine contre les isolats de E. coli et les données de tests de sensibilité ont été obtenus en utilisant la méthode de Kirby Bauer. Un total de six espèces de bactéries :Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Klebsiella pneumoniae, Staphylococcus aureus,  Enterobacter aerogenes ont été isolés à partir d'échantillons d'eau provenant de puits, de forage et des échantillons d'eau de sachet dans la zone d'étude. Les bactéries, les valeurs moyennes se situaient entre 3,74 x 104 à 1,65 x 102 UFC / ml pour le bien et l'eau de forage et de 0,81 à 5,1 x 102 UFC / ml pour les échantillons d'eau de sachet. Sur les 6 souches d'E.coli représentant 27,2% des espèces de bactéries isolées ; deux (33,3 %) des souches ont montré une résistance modéré à haute à la pénicilline. Ces résultats devraient inciter les intervenants en santé publique dans le lieu de l'étude de tenter de réduire la résistance croissante des bactéries  pathogènes dans l'environnement et leurs effets écotoxiques.Mots clés: Résistance aux antibiotiques, pénicilline, qualité l’eau, E. coli

Evolution of the single-hole spectral function across a quantum phase transition in the anisotropic-triangular-lattice antiferromagnet

We study the evolution of the single-hole spectral function when the ground state of the anisotropic-triangular-lattice antiferromagnet changes from the incommensurate magnetically-ordered phase to the spin-liquid state. In order to describe both of the ground states on equal footing, we use the large-N approach where the transition between these two phases can be obtained by controlling the quantum fluctuations via an 'effective' spin magnitude. Adding a hole into these ground states is described by a t-J type model in the slave-fermion representation. Implications of our results to possible future ARPES experiments on insulating frustrated magnets, especially Cs$_2$CuCl$_4$, are discussed.Comment: 8 pages, 7 figure