Development of processes for the production of solar grade silicon from halides and alkali metals, phase 1 and phase 2

High temperature reactions of silicon halides with alkali metals for the production of solar grade silicon are described. Product separation and collection processes were evaluated, measure heat release parameters for scaling purposes and effects of reactants and/or products on materials of reactor construction were determined, and preliminary engineering and economic analysis of a scaled up process were made. The feasibility of the basic process to make and collect silicon was demonstrated. The jet impaction/separation process was demonstrated to be a purification process. The rate at which gas phase species from silicon particle precursors, the time required for silane decomposition to produce particles, and the competing rate of growth of silicon seed particles injected into a decomposing silane environment were determined. The extent of silane decomposition as a function of residence time, temperature, and pressure was measured by infrared absorption spectroscopy. A simplistic model is presented to explain the growth of silicon in a decomposing silane enviroment

Quantum Dynamical Rˇ\check{R}- Matrix with Spectral Parameter from Fusion

A quantum dynamical $\check{R}$-matrix with spectral parameter is constructed by fusion procedure. This spin-1 $\check{R}$-matrix is connected with Lie algebra $so(3)$ and does not satisfy the condition of translation invariance.Comment: 6 pages, LaTeX, no figure

Considering sensing-intuitive dimension to exposition-exemplification in adaptive sequencing

Proceedings of the Second International Conference, AH 2002 Málaga, SpainThe final publication is available at Springer via http://dx.doi.org/10.1007/3-540-47952-X_83This paper shows a way of using sensing-intuitive dimension of learning styles of students in order to improve the efficiency of adaptive learning systems. Firstly, it introduces the procedure of extracting information about sensing-intuitive students from the Felder-Soloman ILS questionnaire. Then, it presents a mechanism of application of sensing-intuitive dimension to exposition-exemplification sequencing. The example used to explain the adaptation effects is taken from a chess course developed with TANGOW, Task-based Adaptive learNer Guidance On the Web.The Spanish Interdepartmental Commission of Science and Technology (CICYT) has sponsored this paper, project number TEL1999-0181 and project number TIC2001-0685-C02-01

The Space Station Photovoltaic Panels Plasma Interaction Test Program: Test plan and results

The Plasma Interaction Test performed on two space station solar array panels is addressed. This includes a discussion of the test requirements, test plan, experimental set-up, and test results. It was found that parasitic current collection was insignificant (0.3 percent of the solar array delivered power). The measured arcing threshold ranged from -210 to -457 V with respect to the plasma potential. Furthermore, the dynamic response of the panels showed the panel time constant to range between 1 and 5 microsec, and the panel capacitance to be between .01 and .02 microF

Subjective burden of government-imposed Covid-19 restrictions in Switzerland: evidence from the 2022 LINK Covid-19 survey

BACKGROUND: While a large literature has quantified the health and economic impact of COVID-19, estimates on the subjective losses in quality of life due to government imposed restrictions remain scarce. METHODS: We conducted a nationally representative online survey in Switzerland in February 2022 to measure average self-reported quality of life with government restrictions. We used a discrete choice experiment to compute average willingness to pay for avoiding specific restrictions and time-trade-off questions to quantify the relative quality of life under restrictions. RESULTS: A total of 1299 Swiss residents completed the online survey between February 9th and 15th, 2022. On average, respondents valued life under severe restrictions at 39% of their usual life (estimated relative utility 0.39 [0.37, 0.42]). Willingness to pay for avoiding restrictions was lowest for masks (CHF 663 [319, 1007]), and highest for schools and daycares (CHF 4123 [3443, 4803]) as well as private parties (CHF 4520 [3811, 5229]). We estimate that between March 2020 and February 2022 a total of 5.7 Million QALYs were lost due to light, moderate and severe restrictions imposed by the governments. CONCLUSIONS: The quality of life losses due to government restrictions are substantial, particularly when it comes to the closure of schools and daycares, as well as the prohibition of private gatherings. Future policies should weigh these costs against the health benefits achievable with specific measures

Geometry of WZW Orientifolds

We analyze unoriented Wess-Zumino-Witten models from a geometrical point of view. We show that the geometric interpretation of simple current crosscap states is as centre orientifold planes localized on conjugacy classes of the group manifold. We determine the locations and dimensions of these planes for arbitrary simply-connected groups and orbifolds thereof. The dimensions of the O-planes turn out to be given by the dimensions of symmetric coset manifolds based on regular embeddings. Furthermore, we give a geometrical interpretation of boundary conjugation in open unoriented WZW models; it yields D-branes together with their images under the orientifold projection. To find the agreement between O-planes and crosscap states, we find explicit answers for lattice extensions of Gaussian sums. These results allow us to express the modular P-matrix, which is directly related to the crosscap coefficient, in terms of characters of the horizontal subgroup of the affine Lie algebra. A corollary of this relation is that there exists a formal linear relation between the modular P- and the modular S-matrix.Comment: 35 pages LaTeX, 2 tables; Proof added for symmetric space relation; minor improvements; references adde

Growth of Inflaton Perturbations and the Post-Inflation Era in Supersymmetric Hybrid Inflation Models

It has been shown that hybrid inflation may end with the formation of non-topological solitons of inflaton field. As a first step towards a fully realistic picture of the post-inflation era and reheating in supersymmetric hybrid inflation models, we study the classical scalar field equations of a supersymmetric hybrid inflation model using a semi-analytical ansatz for the spatial dependence of the fields. Using the minimal D-term inflation model as an example, the inflaton field is evolved using the full 1-loop effective potential from the slow-rolling era to the U(1)_{FI} symmetry-breaking phase transition. Spatial perturbations of the inflaton corresponding to quantum fluctuations are introduced for the case where there is spatially coherent U(1)_{FI} symmetry breaking. The maximal growth of the dominant perturbation is found to depend only on the ratio of superpotential coupling \lambda to the gauge coupling g. The inflaton condensate fragments to non-topological solitons for \lambda/g > 0.09. Possible consequences of non-topological soliton formation in fully realistic SUSY hybrid inflation models are discussed.Comment: 27 pages LaTeX, 8 figures. Additional references and discussio

Cosmology with decaying tachyon matter

We investigate the case of a homogeneous tachyon field coupled to gravity in a spatially flat Friedman-Robertson-Walker spacetime. Assuming the field evolution to be exponentially decaying with time we solve the field equations and show that, under certain conditions, the scale factor represents an accelerating universe, following a phase of decelerated expansion. We make use of a model of dark energy (with p=-\rho) and dark matter (p=0) where a single scalar field (tachyon) governs the dynamics of both the dark components. We show that this model fits the current supernova data as well as the canonical \LambdaCDM model. We give the bounds on the parameters allowed by the current data.Comment: 14 pages, 6 figures, v2, Discussions and references addede