45 research outputs found

    An upgraded ultra-high vacuum magnetron-sputtering system for high-versatility and software-controlled deposition

    Full text link
    Magnetron sputtering is a widely used physical vapor deposition technique. Reactive sputtering is used for the deposition of, e.g, oxides, nitrides and carbides. In fundamental research, versatility is essential when designing or upgrading a deposition chamber. Furthermore, automated deposition systems are the norm in industrial production, but relatively uncommon in laboratory-scale systems used primarily for fundamental research. Combining automatization and computerized control with the required versatility for fundamental research constitutes a challenge in designing, developing, and upgrading laboratory deposition systems. The present article provides a detailed description of the design of a lab-scale deposition chamber for magnetron sputtering used for the deposition of metallic, oxide, nitride and oxynitride films with automated controls, dc or pulsed bias, and combined with a coil to enhance the plasma density near the substrate. LabVIEW software (provided as Supplementary Information) has been developed for a high degree of computerized or automated control of hardware and processes control and logging of process details.Comment: 17 pages, 8 figure

    Forty-five minutes of physical activity at school each day? Curricular promotion of physical activity in grades one to four

    Full text link
    Aim: According to the US Department of Health and Human Services (2008) and the World Health Organization (2008), regular physical activity is essential to the healthy development of children and contributes to the reduction of chronic diseases throughout their life span. However, coordinated comprehensive national and international programs to promote physical activity and sports participation are lacking. According to the German Sports Federation (2006), physical education (PE) classes at German schools are increasingly being canceled or taught outside the school. "fit for pisa" is a German intervention developed in response to the demand for scientific evaluation of interventions like daily physical education. Its goal is to provide quality management-secured, structured and standardized PE instruction by qualified instructors. Subjects and methods: The "fit for pisa" intervention has been implemented at five primary schools in Göttingen, Germany, since 2003. This daily physical education intervention is based on quality standards. At the five primary schools participating in "fit for pisa," students receive a supplementary 3 class hours of PE/week in addition to the mandatory 2 class hours/week for the entire school term. In other words, the children now receive one 45-min session of PE each school day. Daily physical education is now a part of their mandatory school curriculum. The curriculum content and teaching methods have been continuously developed and optimized based on the state guidelines for Lower Saxony. Results: Teacher training is held at the participating schools once a month to promote standardized implementation and quality management of the intervention program. Additional monthly meetings are held so that the teachers can discuss any problems, deviations or other issues occurring in the classes. Checklists are provided for the teachers and external trainers to document the content and objectives of each lesson. Supervisors evaluate the checklists at regular intervals. Using these instruments, the results of the 4-year intervention program were evaluated at the five participating primary schools. Conclusions: This study provides important data for recommendations to implement additional physical education in primary schools, for the corresponding quality assurance instruments and for the optimization of physical education guidelines for primary schools

    a comparative experimental and numerical study of baroclinic wave dynamics

    Get PDF
    The differentially heated rotating annulus is a widely studied tabletop-size laboratory model of the general mid-latitude atmospheric circulation. The two most relevant factors of cyclogenesis, namely rotation and meridional temperature gradient are quite well captured in this simple arrangement. The radial temperature difference in the cylindrical tank and its rotation rate can be set so that the isothermal surfaces in the bulk tilt, leading to the formation of baroclinic waves. The signatures of these waves at the free water surface have been analyzed via infrared thermography in a wide range of rotation rates (keeping the radial temperature difference constant) and under different initial conditions. In parallel to the laboratory experiments, five groups of the MetStröm collaboration have conducted numerical simulations in the same parameter regime using different approaches and solvers, and applying different initial conditions and perturbations. The experimentally and numerically obtained baroclinic wave patterns have been evaluated and compared in terms of their dominant wave modes, spatio-temporal variance properties and drift rates. Thus certain “benchmarks” have been created that can later be used as test cases for atmospheric numerical model validation

    The Origin and Development of the Geometrical Ideas in Arabic Mathematics : The Synopsis of the Geometrical Works of al-Quhi

    Get PDF
    Arabic Mathematics has been characterized as algebra. Compared with this, Arabic geometry had not influence on the later mathematics, and has not been studied so much. However without this geometry, no solution of cubic equations has not completed in Arabic mathematics. We sketch here the synopsis of the geometrical works of Abu Sahl al-Quhl (second half of the tenth century), 'one of the most eminent mathematicians in Iraq', and investigate the origin and development of his geometrical ideas. Thirty three mathematical works are attributed to him, and almost of them are geometrical. His ideas were from Archimedes, Euclid and Apollonius. The opus magnum of the last one is indispensable for al-Quhl's works, and in the field of conic sections he contributed much. He completed the lacuna of the Greek mathematics, and developed it further. For showing this aspect four treatises are presented with partial translations. 'On Tangent Circles' investigated Apollonian circle problems further, and 'On the Trisection of Angle' solved the famous problem by Apollonian conic sections. 'On the Motion' was a unique treatise in Arabic mathematics, for it dealt with infinity which had been avoided in Greek mathematics. 'On the Perfect Compass (an instrument to draw conies by continuous moving)' gave an idea on the new classification of curves, which anticipates the seventeenth-century European mathematics. The problems and method which he used seems to be analytical and purely Greek, and he might be called as the last Greek-style mathematician. The atmosphere where he studied shows that Arabic science developed under a kind of patronage, and the manuscripts containing his treatises shows that Greek geometry was well established at his times. In conclusion, geometry flourished in Arabic world of the tenth century, and its results were over the Greek ones, and might be compared to the early modern mathematics in Europe

    A four-surface schematic eye of macaque monkey obtained by an optical method

    Get PDF
    AbstractSchematic eyes for four Macaca fascicularis monkeys were constructed from measurements of the positions and curvatures of the anterior and posterior surfaces of the cornea and lens. All of these measurements were obtained from Scheimpflug photography through the use of a ray-tracing analysis. Some of these measurements were also checked (and confirmed) by keratometry and ultrasound. Gaussian lens equations were applied to the measured dimensions of each individual eye in order to construct schematic eyes. The mean total power predicted by the schematic eyes agreed closely with independent measurements based on retinoscopy and ultrasound results, 74.2 ± 1.3 (SEM) vs 74.7 ± 0.3 (SEM) diopters. The predicted magnification of 202 μm/deg in one eye was confirmed by direct measurement of 205 μm/deg for a foveal laser lesion. The mean foveal retinal magnification calculated for our eight schematic eyes was 211 ± (SEM) μm/deg, slightly less than the value obtained by application of the method of Rolls and Cowey [Experimental Brain Research, 10, 298–310 (1970)] to our eight eyes but just 4% more than the value obtained by application of the method of Perry and Cowey [Vision Research, 12, 1795–1810 (1985)]

    A depauperate immune repertoire precedes evolution of sociality in bees

    Get PDF
    Background Sociality has many rewards, but can also be dangerous, as high population density and low genetic diversity, common in social insects, is ideal for parasite transmission. Despite this risk, honeybees and other sequenced social insects have far fewer canonical immune genes relative to solitary insects. Social protection from infection, including behavioral responses, may explain this depauperate immune repertoire. Here, based on full genome sequences, we describe the immune repertoire of two ecologically and commercially important bumblebee species that diverged approximately 18 million years ago, the North American Bombus impatiens and European Bombus terrestris. Results We find that the immune systems of these bumblebees, two species of honeybee, and a solitary leafcutting bee, are strikingly similar. Transcriptional assays confirm the expression of many of these genes in an immunological context and more strongly in young queens than males, affirming Bateman’s principle of greater investment in female immunity. We find evidence of positive selection in genes encoding antiviral responses, components of the Toll and JAK/STAT pathways, and serine protease inhibitors in both social and solitary bees. Finally, we detect many genes across pathways that differ in selection between bumblebees and honeybees, or between the social and solitary clades. Conclusions The similarity in immune complement across a gradient of sociality suggests that a reduced immune repertoire predates the evolution of sociality in bees. The differences in selection on immune genes likely reflect divergent pressures exerted by parasites across social contexts

    Minimal Induced Drag for Non-Planar Lifting Surfaces with Moderate and Small Aspect Ratio

    No full text
    Summary The induced drag of non-planar wings is compared to that of planar wings which result from unfolding the non-planar ones. It is shown that due to the induced lift, there exist non-planar configurations with positive span camber that have an overall aerodynamic performance increase in comparison to the planar ones. The induced lift and increment of aerodynamic performance increases with decreasing aspect ratio. The effect is opposite for configurations with negative camber. Without the induced lift, the positive non-planar configuration would have more induced drag. Analysis is performed using a lifting line method, which takes into account the induced lift, and using Euler solutions. For the inviscid solutions, the induced drag is obtained with a far-field drag analysis method

    Numerical Implications of Spanwise Camber on Minimum Induced Drag Configurations

    No full text
    Lifting line and Euler techniques have indicated that an elliptical planform cambered in the spanwise direction appears to have a lower induced drag than the uncambered, planar configuration, when both of then have identical arc lengths and the same wetted areas. In other words, a wing geometry with a lower projected span than the planar wing, only because of spanwise cambering, has been found to have a lower induced drag than the corresponding planar case. It was also noted that in the Euler solutions the theoretical minimum induced drag was not achieved on a planar configuration without applying a twist distribution. The increased efficiency of the non-planar configuration is due to induced lift and without accounting for this induced lift, the induced drag is larger then that of the corresponding unfolded planar wing. Induced lift and aerodynamic efficiency of the spanwise cambered configuration was observed to increase with reduced aspect ratio

    Molecular Cytogenetics: Genomic Imbalances in Colorectal Cancer and their Clinical Impact

    No full text
    Chromosomal aberrations play a dominant role in colorectal carcinogenesis. The application of fluorescence in situ hybridization (FISH) based techniques such as comparative genomic hybridization (CGH) and spectral karyotyping (SKY) revealed that colorectal carcinomas are characterized by a specific pattern of chromosomal imbalances which sequentially accumulate during cancer progression. This review aims to summarize molecular cytogenetic studies, provides a background on the functional relevance of chromosomal aberrations for colorectal cancer progression and discusses their potential clinical impact
    corecore