Low temperature specific heat of vanadium carbide

Low temperature specific heat measurements on vanadium carbide crystal

Optical and Infrared Spectroscopy

Contains research objectives, summary of research and reports on four research projects.Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)National Aeronautics and Space Administration (Grant NGR-22-009-237)U. S. Air Force Cambridge Research Laboratories Contract AF 19(628)-606

On the de Haas-van Alphen effect in inhomogeneous alloys

We show that Landau level broadening in alloys occurs naturally as a consequence of random variations in the local quasiparticle density, without the need to consider a relaxation time. This approach predicts Lorentzian-broadened Landau levels similar to those derived by Dingle using the relaxation-time approximation. However, rather than being determined by a finite relaxation time $\tau$, the Landau-level widths instead depend directly on the rate at which the de Haas-van Alphen frequency changes with alloy composition. The results are in good agreement with recent data from three very different alloy systems.Comment: 5 pages, no figure

‘When I look at this van, it’s not only a van’: symbolic objects in the policing of migration

The ‘Go Home Van’ was the centrepiece of the UK government’s 2013 immigration enforcement campaign. Vehicles were driven around ethnically diverse London neighbourhoods clad with giant posters offering irregular migrants a choice between ‘voluntary departure’ and criminal arrest. Abandoned shortly afterwards in response to complaints, the GHV nonetheless had a significant impact on migrants. Through interviews and focus groups, this article investigates what was conveyed by the van, and the means by which it achieved these effects. We find that the GHV communicated meanings about the illegitimacy and criminality of migrants, with its material characteristics (visibility and mobility) as important as the words and pictures on its surface. Migrants sought to resist the van through hiding, while support organisations rejected dominant meanings and crafted alternatives. The article establishes a research agenda around the wider role of symbolic objects, in the context of the global migration crisis

Applications of laser annealing and laser-induced diffusion to photovoltaic conversion

Over the past several years it has been demonstrated that a variety of techniques involving pulsed laser irradiation of both single crystal and polycrystalline silicon by pulsed lasers can result in the reproducible achievement of high efficiency silicon solar cells. Pulsed laser annealing (PLA) after an ion implantation (II) step results in melting (for a time of order 100 nsec) and essentially defect-free liquid phase epitaxial regrowth within approx. 0.5 ..mu..m of the surface. Complete electrical activation of a number of dopant ions, at concentrations exceeding ordinary solubility limits, has been demonstrated and crystalline (polycrystalline) silicon solar cell efficiencies of 16.6% (12.5%) have been obtained. Other p-n junction and solar cell fabrication techniques have been demonstrated. Pulsed laser processing has also been demonstrated to have several other unique and beneficial advantages in polycrystalline silicon substrates. For example, grain boundaries do not exist during laser melting, while dopant diffusion is taking place; the short melt durations involved further limit dopant diffusion; precipitates present after conventional high temperature dopant diffusion can be removed; and, certain types of electrically active grain boundaries can be made inactive by pulsed laser irradiation. Finally, grain growth in fine-grained polycrystalline silicon films, via pulsed laser melting and recrystallization, has been demonstrated. Because little is known about the application of similar pulsed laser processing techniques to compound semiconductors, particularly in connection with the formation of shallow p-n junctions, research has been devoted to studies of pulsed laser processing of GaAs and compound semiconductor solar cell fabrication techniques that are compatible with the use of pulsed lasers. Progress is reported. (WHK

Strongly Enhanced Current Densities in Superconducting Coated Conductors of YBa2Cu3O7-x + BaZrO3

There are numerous potential applications for superconducting tapes, based on YBa2Cu3O7-x (YBCO) films coated onto metallic substrates. A long established goal of more than 15 years has been to understand the magnetic flux pinning mechanisms which allow films to maintain high current densities out to high magnetic fields. In fact, films carry 1-2 orders of magnitude higher current densities than any other form of the material. For this reason, the idea of further improving pinning has received little attention. Now that commercialisation of conductors is much closer, for both better performance and lower fabrication costs, an important goal is to achieve enhanced pinning in a practical way. In this work, we demonstrate a simple and industrially scaleable route which yields a 1.5 to 5-fold improvement in the in-field current densities of already-high-quality conductors

Book Reviews

An Estate Planner\u27s Handbook By Mayo Adams Shattuck Boston: Little, Brown & Company, 1948. Pp. 575. $7.50 reviewer: Philip A. Hendrick ================================ Estate Planning and Estate Tax Saving By Edward N. Polisher Philadelphia: George T. Bisel Company. Second Edition, 1948. 2 Volumes. Pp. xxxii, 923.$20.00 reviewer: Charles L.B. Lowndes =============================== Federal Taxes--Corporations and Partnerships, 1948-49 By Robert H. Montgomery, Conrad B. Taylor and Mark E. Richardson Vol. I: Gross Income and Deductions Vol. II: Taxes, Returns and Administration New York: The Ronald Press Company, 1948. Pp. xiii, 1001; pp. iv, 881. $20.00 Federal Taxes--Estates, Trusts and Gifts, 1948-49 By Robert H. Montgomery and James 0. Wynn New York: The Ronald Press Company,1948. Pp. xi, 1263.$10.00 reviewer: Adrian W. DeWind ================================ Wills, Gifts and Estate Planning Under the 1948 Revenue Act By Seymour S. Mintz, Richard C. Flesch and Bernard Soman Washington: The Bureau of National Affairs, Inc., 1948. Pp. 328. $2.00 reviewer: Chas. A. Morehead =============================== Federal Taxation for the Lawyer By Houstin Shockey New York: Prentice-Hall, Inc., Second Edition, 1947. Pp. xiii, 396.$5.00 reviewer: John R. Stiver

Task analysis method for procedural training curriculum development

A central venous catheter (CVC) is an important medical tool used in critical care and emergent situations. Integral to proper care in many circumstances, insertion of a CVC introduces the risk of central line-associated blood stream infections and mechanical adverse events; proper training is important for safe CVC insertion. Cognitive task analysis (CTA) methods have been successfully implemented in the medical field to improve the training of postgraduate medical trainees, but can be very time-consuming to complete and require a significant time commitment from many subject matter experts (SMEs). Many medical procedures such as CVC insertion are linear processes with well-documented procedural steps. These linear procedures may not require a traditional CTA to gather the information necessary to create a training curriculum. Accordingly, a novel, streamlined CTA method designed primarily to collect cognitive cues for linear procedures was developed to be used by medical professionals with minimal CTA training. This new CTA methodology required fewer trained personnel, fewer interview sessions, and less time commitment from SMEs than a traditional CTA. Based on this study, a streamlined CTA methodology can be used to efficiently gather cognitive information on linear medical procedures for the creation of resident training curricula and procedural skills assessments

Field Emission and Nanostructure of Carbon Films

The results of field emission measurements of various forms of carbon films are reported. It is shown that the films nanostructure is a crucial factor determining the field emission properties. In particular, smooth, pulsed-laser deposited amorphous carbon films with both high and low sp3 contents are poor field emitters. This is similar to the results obtained for smooth nanocrystalline, sp2-bonded carbon films. In contrast, carbon films prepared by hot-filament chemical vapor deposition (HE-CVD) exhibit very good field emission properties, including low emission turn-on fields, high emission site density, and excellent durability. HF-CVD carbon films were found to be predominantly sp2-bonded. However, surface morphology studies show that these films are thoroughly nanostructured, which is believed to be responsible for their promising field emission properties