29,186 research outputs found
Apparatus and method for heating a material in a transparent ampoule
An improved process for heating a material within a fused silica ampoule by radiation through the wall of the ampoule, while simultaneously passing a cooling gas around the ampoule is described. The radiation passes through a screen of fused silica so as to remove those components capable of directly heating the silica, therby increasing the temperature of the material within the ampoule above the strain point of the ampoule, while maintaining the exterior of the ampoule cool enough to prevent rupturing the amp
Space processing of electronic materials
The bulk growth of solid solution alloys of mercury telluride and cadmium telluride is discussed. These alloys are usually described by the formula Hg1-xCdxTe, and are useful for the construction of infrared detectors. The electronic energy band gap can be controlled between zero and 1.6 electron volts by adjusting the composition x. The most useful materials are at x approximately 20%, suitable for detection wavelengths of about 10 micrometers. The problems of growing large crystals are rooted in the wide phase diagram of the HgTe-CdTe pseudobinary system which leads to exaggerate segregation in freezing, constitutional supercooling, and other difficulties, and in the high vapor pressure of mercury at the growth temperatures, which leads to loss of stoichiometry and to the necessity of working in strong, pressure resistant sealed containers
High-temperature, high-pressure optical cell
The invention is an optical cell for containment of chemicals under conditions of high temperature and high pressure. The cell is formed of a vitreous silica tube, two optical windows comprising a vitreous silica rod inserted into the ends of a tube, and fused into position in the tube ends. Windows are spaced apart to form a cavity enclosed by the tube and the windows. A hole is drilled radially through the tube and into the cavity. Another vitreous silica tube is fused to the silica tube around the hole to form the stem, which is perpendicular to the long axis of the tube. The open end of the stem is used to load chemicals into the cavity. Then the stem may be sealed, and if desired, it may be shortened in order to reduce the volume of the cavity, which extends into the stem
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Optimising multi-disciplinary contributions for the smart clothing development process
This research aims to introduce a strategic approach to overcome the creative boundaries and optimize multidisciplinary contributions in Smart Clothing development, since the former research results revealed that these issues are key to achieving fully integrated Smart Clothes. Therefore, this paper examines collaborative projects that are shown to break through the creative boundary and integrate multidisciplinary contributions, and identifies how individual designers overcome their creative constraints and collaborate with others, in order to identify a practical method. The research result indicates that a clear description of Smart Clothingâs context will provide a new framework for the developers to work on
Simple applications of Noether's first theorem in quantum mechanics and electromagnetism
Internal global symmetries exist for the free non-relativistic
Schr\"{o}dinger particle, whose associated Noether charges--the space integrals
of the wavefunction and the wavefunction multiplied by the spatial
coordinate--are exhibited. Analogous symmetries in classical electromagnetism
are also demonstrated.Comment: 12 page
Transitions and progress: teachers' views of progress in attainment of pupils age 5-10
There has been a longstanding concern in England and Wales with the year on year progress made by pupils, but particularly at times of change, such as transfer from primary to secondary school at age 11. In Coalton, a former mining town in the North of England, a five year UK government funded initiative known as Charter for Transition has been put in place to try to overcome some of these difficulties and improve the learning opportunities for pupils aged 5-16. The programme takes place over a 5-year period in various stages, but in this paper we make use of data from the first two years. The research team examines the viewpoints of teachers from schools that were receiving additional support in their efforts to raise achievement in phase one and the pilot phase of the project about what they saw as the main benefits of this work. We present the beginnings of our exploration of teachersâ judgements of this work, and what they saw as the difficulties with associating the project with pupil attainment.</p
Comment on "Quantum back-reaction through the Bohmian particle"
In this Comment I point out some limitations of the proposal of Prezhdo and
Brooksby for coupling quantum and classical degrees of freedom
(Phys.Rev.Lett.86(2001)3215) if it is pushed too far.Comment: 1 page, REVTEX, no figure
Reversible and irreversible evolution of a condensed bosonic gas
We have formulated a kinetic theory for a condensed atomic gas in a trap,
i.e., a generalized Gross-Pitaevskii equation, as well as a quantum-Boltzmann
equation for the normal and anomalous fluctuations [R. Walser et al., Phys.
Rev. A, 59, 3878 (1999)]. In this article, the theory is applied to the case of
an isotropic configuration and we present numerical and analytical results for
the reversible real-time propagation, as well as irreversible evolution towards
equilibrium.Comment: 15 pages RevTeX, 8 figures, reviewed PRA resubmissio
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Proton irradiation of EMCCDs
This paper describes the irradiation of 95 electron multiplication charge coupled devices (EMCCDs) at the Paul Scherrer Institut (PSI) in Switzerland, to investigate the effects of proton irradiation on the operational characteristics of CCDs featuring electron multiplication technology for space use. This work was carried out in support of the CCD development for the radial velocity spectrometer (RVS) instrument of the European Space Agency's cornerstone Gaia mission. Previous proton irradiations of EMCCDs, have shown the technology to be radiation hard to /spl sim/10/spl times/ the required six-year Gaia lifetime proton fluence, with no device failures or unexpected operational changes. The purpose of the study described in this paper was to further investigate the statistical probability of device failure as a result of radiation damage, the large number of devices and high proton fluence used, making the study equivalent to testing /spl sim/50 complete RVS CCD focal planes to the expected end of life proton dose. An outline of the earlier EMCCD proton irradiations is given, followed by a detailed description of the proton irradiation and characterization of the 95 devices used in this latest study
The development of the professional values and practice standard in the secondary graduate initial teacher training route in England
The paper reports on a pilot research project to investigate how trainee teachers develop an understanding of the competences that must be reached in the area of professional practice and values , which is one of the standards that needs to be met before the award of Qualified Teacher Status in England. Data were collected from secondary trainee teachers, their placement mentors in schools and university tutors. Data have been interpreted in the context of potential threats to the professionalism of teachers, through the introduction of managerialist influences in public funded education. The main findings are: that trainees think that the most dominant influence on developing understanding of professional values are their school placements ; there were little differences in the responses from four subject areas studied ; mentors and other lead teachers play an important role in the development of understanding of professional values; the grades awarded by mentors when assessing professional practice and values varies between the four subjects studied. The explanation for these findings is complex and is related to the understanding and interpretation of the standard by both mentors and trainee teachers. The findings highlight some of the difficulties in attempting to assess competency standards in an area that is underpinned by values and suggest that initial teacher training can best assist the development of the standard when it is approached in a critical way by all parties.</p
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