Application of a diode array spectroradiometer to measuring the spectral scattering properties of cloud types in a laboratory

International audienceIn the last few years diode array spectroradiometers have become useful complements to traditional scanning instruments when measuring visible and ultraviolet solar radiation incident on the ground. This study describes the application of such an instrument to the problem of measuring the radiation scattered by different cloud-types in a laboratory environment. Details of how the instrument is incorporated into the experimental set-up are given together with the development of the system as a whole. The capability to measure a full spectrum for each scattering angle is an undoubted advantage, although the limited sensitivity impacts on the usefulness for optically thin clouds. Nevertheless example results are presented: (1) scattering phase functions at a range of wavelengths recorded simultaneously for water clouds, showing spectral deviation at the rainbow angle and verification of Mie theory; (2) likewise for mixed phase clouds, with evidence of both halo and rainbow features in a single scattering function; and, (3) detail of the forward scattering region in a glaciated cloud showing a barely perceptible halo feature, with implications for the small-scale structure of the ice crystals produced

SLICES: Critical Theory as Praxis and Research-Based Service Learning

Abstract: In an era of increasing racial and ethnic diversity, both in the larger U.S. society and in institutions of higher education, using teaching strategies that explicitly address racial justice can be a meaningful way to engage a diverse student. Service Learning Initiative for Community Engagement in Sociology (SLICES) is a research-based program in the Department of Sociology at the University of Nevada, Las Vegas that uses critical theories as praxis to foster academic and professional development, and civic engagement while paying particular attention racial justice. This paper describes the use of Feminist Standpoint Theory and Information Has Value as theoretical tools for course curriculum development, larger program design, and community involvement. Key words: critical theory, Feminist Standpoint Theory, service learning, community based participatory action research, Information Has Value Acknowledgements: The authors would like to extend our appreciation the two blind reviewers for their thoughtful and comprehensive comments. SLICES’ work would not be possible without the support of our UNLV campus partners. We would like to thank the Office of Student Engagement and Diversity, the Office of Undergraduate Research, University Libraries Social Sciences Librarian, Heidi Johnson, and the Office of Career Services. We would also like to thank Sociologists for Women in Society for their generous support from the Social Action Grant and the Nevada System of Higher Education Regents Service Award program funding support for SLICES staffing positions. And the first author would like to thank José Luis Meléndrez, M.S.W., Executive Director of Community Partnerships, UNLV School of Community Health, for modeling commitment to community engagement and mentorship

AIR multigrid with GMRES polynomials (AIRG) and additive preconditioners for Boltzmann transport

We develop a reduction multigrid based on approximate ideal restriction (AIR) for use with asymmetric linear systems. We use fixed-order GMRES polynomials to approximate $A_\textrm{ff}^{-1}$ and we use these polynomials to build grid transfer operators and perform F-point smoothing. We can also apply a fixed sparsity to these polynomials to prevent fill-in. When applied in the streaming limit of the Boltzmann Transport Equation (BTE), with a P$^0$ angular discretisation and a low-memory spatial discretisation on unstructured grids, this "AIRG" multigrid used as a preconditioner to an outer GMRES iteration outperforms the lAIR implementation in hypre, with two to three times less work. AIRG is very close to scalable; we find either fixed work in the solve with slight growth in the setup, or slight growth in the solve with fixed work in the setup when using fixed sparsity. Using fixed sparsity we see less than 20% growth in the work of the solve with either 6 levels of spatial refinement or 3 levels of angular refinement. In problems with scattering AIRG performs as well as lAIR, but using the full matrix with scattering is not scalable. We then present an iterative method designed for use with scattering which uses the additive combination of two fixed-sparsity preconditioners applied to the angular flux; a single AIRG V-cycle on the streaming/removal operator and a DSA method with a CG FEM. We find with space or angle refinement our iterative method is very close to scalable with fixed memory use

Empirical comparison of high gradient achievement for different metals in DC and pulsed mode

For the SwissFEL project, an advanced high gradient low emittance gun is under development. Reliable operation with an electric field, preferably above 125 MV/m at a 4 mm gap, in the presence of an UV laser beam, has to be achieved in a diode configuration in order to minimize the emittance dilution due to space charge effects. In the first phase, a DC breakdown test stand was used to test different metals with different preparation methods at voltages up to 100 kV. In addition high gradient stability tests were also carried out over several days in order to prove reliable spark-free operation with a minimum dark current. In the second phase, electrodes with selected materials were installed in the 250 ns FWHM, 500 kV electron gun and tested for high gradient breakdown and for quantum efficiency using an ultra-violet laser.Comment: 25 pages, 13 figures, 5 tables. Follow up from FEL 2008 conference (Geyongju Korea 2008) New Title in JVST A (2010) : Vacuum breakdown limit and quantum efficiency obtained for various technical metals using DC and pulsed voltage source

The Physicist's Guide to the Orchestra

An experimental study of strings, woodwinds (organ pipe, flute, clarinet, saxophone and recorder), and the voice was undertaken to illustrate the basic principles of sound production in music instruments. The setup used is simple and consists of common laboratory equipment. Although the canonical examples (standing wave on a string, in an open and closed pipe) are easily reproduced, they fail to explain the majority of the measurements. The reasons for these deviations are outlined and discussed.Comment: 11 pages, 10 figures (jpg files). Submitted to European Journal of Physic

Risk Factors for Swine Infection with Toxoplasma gondii

The objective of this study was to evaluate the association between the seroprevalence of Toxoplasma gondii antibodies in swine in commercial pork production systems in Iowa, USA and the source of water (surface water vs. well water vs. rural processed water) and method of water delivery (surface or trough vs. nipple vs. cup). Also the study evaluated the association between T. gondii seroprevalence and other selected potential farm variables

The IKMC web portal: a central point of entry to data and resources from the International Knockout Mouse Consortium

The International Knockout Mouse Consortium (IKMC) aims to mutate all protein-coding genes in the mouse using a combination of gene targeting and gene trapping in mouse embryonic stem (ES) cells and to make the generated resources readily available to the research community. The IKMC database and web portal (www.knockoutmouse.org) serves as the central public web site for IKMC data and facilitates the coordination and prioritization of work within the consortium. Researchers can access up-to-date information on IKMC knockout vectors, ES cells and mice for specific genes, and follow links to the respective repositories from which corresponding IKMC products can be ordered. Researchers can also use the web site to nominate genes for targeting, or to indicate that targeting of a gene should receive high priority. The IKMC database provides data to, and features extensive interconnections with, other community databases

Ethnic Minorities and their Health Needs: Crisis of Perception and Behaviours

There is considerable evidence to suggest that racial and ethnic disparities exist in the provision of emergency and wider healthcare. The importance of collecting patient ethnic data has received attention in literature across the world and eliminating ethnic and racial health equalities is one of the primary aims of healthcare providers internationally. The poor health status of certain racial and ethnic groups has been well documented. The improvement of racial and ethnic disparities in healthcare is at the forefront of many public health agendas. This article addresses important policy, practice, and cultural issues confronted by the pre-hospital emergency care setup. This aspect of care plays a unique role in the healthcare safety net in providing a service to a very diverse population, including members of ethnic and racial minorities. Competent decision making by the emergency care practitioners requires patient-specific information and the health provider's prior medical knowledge and clinical training. The article reviews the current ethnicity trends in the UK along with international evidence linking ethnicity and health inequalities. The study argues that serious difficulties will arise between the health provider and the patient if they come from different backgrounds and therefore experience difficulties in cross-cultural communication. This adversely impacts on the quality of diagnostic and clinical decision making for minority patients. The article offers few strategies to address health inequalities in emergency care and concludes by arguing that much more needs to be done to ensure that we are hearing the voices of more diverse groups, groups who are often excluded from engagement through barriers such as language or mobility difficulties