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

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

Determining intended evidence relations in natural language arguments

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72555/1/j.1467-8640.1991.tb00386.x.pd

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

Energy Recovery Linac: Photocathode Deposition and Transport System

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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

Shell formation and star formation in superbubble DEM 192

Was star formation in the OB associations, LH 51 and LH 54, triggered by the growth of the superbubble DEM 192? To examine this possibility, we investigate the stellar contents and star formation history, and model the evolution of the shell. H-R diagrams constructed from UBV photometry and spectral classifications indicate highly coeval star formation, with the entire massive star population having an age of ~< 2-3 Myr. However, LH 54 is constrained to an age of ~3 Myr by the presence of a WR star, and the IMF for LH 51 suggests a lower-mass limit implying an age of 1-2 Myr. There is no evidence of an earlier stellar population to create the superbubble, but the modeled shell kinematics are consistent with an origin due to the strongest stellar winds of LH 54. It might therefore be possible that LH 54 created the superbubble, which in turn may have triggered the creation of LH 51. Within the errors, the spatial distribution of stellar masses and IMF appear uniform within the associations. We reinvestigate the estimates for stellar wind power L_w(t), during the H-burning phase, and note that revised mass-loss rates yield a significantly different form for L_w(t), and may affect stellar evolution timescales. We also model superbubble expansion into an ambient medium with a sudden, discontinuous drop in density, and find that this can easily reproduce the anomalously high shell expansion velocities seen in many superbubbles.Comment: 18 pages, 12 figures, AASTeX; Figure 1 bitmapped. Accepted to AJ. Table of Contents and preprint, including hi-resolution version of Figure 1, available at: http://www.ast.cam.ac.uk/~oey/oeypubs.htm

Balancing prescription with teacher and pupil agency : spaces for manoeuvre within a pedagogical model for working with adolescent girls

This paper explores the possibilities of using a pedagogical model for working with adolescent girls in physical education as a means of balancing the challenge of external prescription from outside the school with teacher and pupil agency. We report data from a study involving four schools in Glasgow. We note that the national curriculum for Scotland, Curriculum for Excellence, is a broad and bold type that provides teachers with ‘spaces for manoeuvre’ in order to shape local curricula that best meet the needs and interests of girls. This is particularly the case in physical education, which in the Basic General Education phase for 12-15 years olds there is no well-established assessment regime. We identify four spaces for manoeuvre for teachers and pupils within an activist model: new forms of communication based on authorising pupil voice; offering choices and opening up learning possibilities; the co-construction of a safe class environment; and opportunities to rethink traditional structures based on the multi-activity curriculum form. We conclude that an activist pedagogical model provided teachers and pupils with spaces to explore alternative practices to traditional forms of physical education

Intercomparison of solar UV direct irradiance spectral measurements at Izana in June 2005

Spectral measurements of direct solar ultraviolet irradiance are very important for many applications in the field of atmospheric sciences. Despite its usefulness, few UV monitoring sites include such measurements in their regular observational programs. Standardization of measurement methodologies and calibration techniques is required in order to reach the quality standard of global irradiance measurements. This study presents preliminary results from an intercomparison campaign of seven UV spectroradiometers of different types that took place at the high altitude site of Izana (28.3°N, 16.5°W, 2367 m above sea level), in Tenerife, Canary Islands in June 2005