Silicon web process development

A barrier crucible design which consistently maintains melt stability over long periods of time was successfully tested and used in long growth runs. The pellet feeder for melt replenishment was operated continuously for growth runs of up to 17 hours. The liquid level sensor comprising a laser/sensor system was operated, performed well, and meets the requirements for maintaining liquid level height during growth and melt replenishment. An automated feedback loop connecting the feed mechanism and the liquid level sensing system was designed and constructed and operated successfully for 3.5 hours demonstrating the feasibility of semi-automated dendritic web growth. The sensitivity of the cost of sheet, to variations in capital equipment cost and recycling dendrites was calculated and it was shown that these factors have relatively little impact on sheet cost. Dendrites from web which had gone all the way through the solar cell fabrication process, when melted and grown into web, produce crystals which show no degradation in cell efficiency. Material quality remains high and cells made from web grown at the start, during, and the end of a run from a replenished melt show comparable efficiencies

Observational Constraints on Interstellar Grain Alignment

We present new multicolor photo-polarimetry of stars behind the Southern Coalsack. Analyzed together with multiband polarization data from the literature, probing the Chamaeleon I, Musca, rho Opiuchus, R CrA and Taurus clouds, we show that the wavelength of maximum polarization (lambda_max) is linearly correlated with the radiation environment of the grains. Using Far-Infrared emission data, we show that the large scatter seen in previous studies of lambda_max as a function of A_V is primarily due to line of sight effects causing some A_V measurements to not be a good tracer of the extinction (radiation field strength) seen by the grains being probed. The derived slopes in lambda_max vs. A_V, for the individual clouds, are consistent with a common value, while the zero intercepts scale with the average values of the ratios of total-to-selective extinction (R_V) for the individual clouds. Within each cloud we do not find direct correlations between lambda_max and R_V. The positive slope in consistent with recent developments in theory and indicating alignment driven by the radiation field. The present data cannot conclusively differentiate between direct radiative torques and alignment driven by H_2 formation. However, the small values of lambda_max(A_V=0), seen in several clouds, suggest a role for the latter, at least at the cloud surfaces. The scatter in the lambda_max vs. A_V relation is found to be associated with the characteristics of the embedded Young Stellar Objects (YSO) in the clouds. We propose that this is partially due to locally increased plasma damping of the grain rotation caused by X-rays from the YSOs.Comment: Accepted for publication in the Astrophysical Journa

A GLIMPSE into the Nature of Galactic Mid-IR Excesses

We investigate the nature of the mid-IR excess for 31 intermediate-mass stars that exhibit an 8 micron excess in either the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire or the Mid-Course Space Experiment using high resolution optical spectra to identify stars surrounded by warm circumstellar dust. From these data we determine projected stellar rotational velocities and estimate stellar effective temperatures for the sample. We estimate stellar ages from these temperatures, parallactic distances, and evolutionary models. Using MIPS [24] measurements and stellar parameters we determine the nature of the infrared excess for 19 GLIMPSE stars. We find that 15 stars exhibit Halpha emission and four exhibit Halpha absorption. Assuming that the mid-IR excesses arise in circumstellar disks, we use the Halpha fluxes to model and estimate the relative contributions of dust and free-free emission. Six stars exhibit Halpha fluxes that imply free-free emission can plausibly explain the infrared excess at [24]. These stars are candidate classical Be stars. Nine stars exhibit Halpha emission, but their Halpha fluxes are insufficient to explain the infrared excesses at [24], suggesting the presence of a circumstellar dust component. After the removal of the free-free component in these sources, we determine probable disk dust temperatures of Tdisk~300-800 K and fractional infrared luminosities of L(IR)/L(*)~10^-3. These nine stars may be pre-main-sequence stars with transitional disks undergoing disk clearing. Three of the four sources showing Halpha absorption exhibit circumstellar disk temperatures ~300-400 K, L(IR)/L(*)~10^-3, IR colors K-[24]< 3.3, and are warm debris disk candidates. One of the four Halpha absorption sources has K-[24]> 3.3 implying an optically thick outer disk and is a transition disk candidate.Comment: 17 figures. Accepted for publication in Ap

Dynamics of myelin content decrease in the rat stroke model

A majority of studies were usually focused on neuronal death after brain ischemia, however, stroke affects all cell types including oligodendrocytes that form myelin sheath in the CNS. Our study is focused on the changes of myelin content in ischemic core and neighbor structures in early terms (1, 3 and 10 days) after stroke. Stroke modeled with middle cerebral artery occlusion (MCAo) in 15 male rats that were divided in three groups by time-points after operation. Brain sections were histologically stained with Luxol Fast Blue (LFB) for myelin quantification. The significant demyelination was found in the ischemic core, corpus callosum, anterior commissure, whereas myelin content was increased in caudoputamen, internal capsule and piriform cortex compared with the contralateral hemisphere. The motor cortex showed a significant increase of myelin content on the 1st day and a significant decrease on the 3rd and 10th days after MCAo. These results suggest stroke influences myelination not only in ischemic core but also in distant structures

Создание опытного образца геохода. Временной фактор изготовления компонентов и их сборки в конечное изделие

Изложен опыт реализации проекта №02.G25.31.0076 в рамках открытого конкурса Министерства образования и науки РФ и Постановления Правительства РФ №218 от 09.04.2010 г. Дано описание временных рамок реализации проекта, в частности, работы над созданием опытного образца щитового проходческого агрегата - геохода, диаметром 3,2 м. В настоящее время проект находится в стадии завершения. Главная идея статьи - поделиться опытом создания новой техники и показать, сколько времени затрачивается на решение тех или иных производственных процессов по созданию опытных образцов горных машин на примере геохода. Данная статья будет полезна организациям, планирующим участие в реализации проектов по созданию высокотехнологичного производства, и может являться ориентиром для составления Плана-графика реализации подобных проектов. Автор статьи лично принимал участие в реализации данного проекта и принимал решения по планированию и организации работ.The experience of the project №02.G25.31.0076 is presented. The project was operated in the framework of the open competition of the Ministry of education and science of the Russian Federation and the RF Government Decree №218 from 09.04.2010. Description of the time frame of the project implementation, particularly the activities of the TBM prototype creation - geokhod, with a diameter of 3.2 m. is presented. Currently, the project is closer to complete. The main idea of the article is to share the experience of creating new technology and show how much time is spent on the decision of production processes to create prototypes of mining machines on the example of a geokhod. This article will be useful for organizations planning to participate in the implementation of projects to create high-tech production, and can be a guide for drawing up a Plan-schedule of such projects. The author of this article personally participated in the implementation of this project and made decisions on planning and organization of activities

Silicon web process development

Silicon dendritic web, a single crystal ribbon shaped during growth by crystallographic forces and surface tension (rather than dies), is a highly promising base material for efficient low cost solar cells. The form of the product smooth, flexible strips 100 to 200 microns thick, conserves expensive silicon and facilitates automation of crystal growth and the subsequent manufacturing of solar cells. These characteristics, coupled with the highest demonstrated ribbon solar cell efficiency-15.5%-make silicon web a leading candidate to achieve, or better, the 1986 Low Cost Solar Array (LSA) Project cost objective of 50 cents per peak watt of photovoltaic output power. The main objective of the Web Program, technology development to significantly increase web output rate, and to show the feasibility for simultaneous melt replenishment and growth, have largely been accomplished. Recently, web output rates of 23.6 sq cm/min, nearly three times the 8 sq cm/min maximum rate of a year ago, were achieved. Webs 4 cm wide or greater were grown on a number of occassions

Percutaneous Sclerotherapy of Venous Malformations of the Hand: A Multicenter Analysis

PURPOSE To evaluate the safety and outcome of percutaneous sclerotherapy for treating venous malformations (VMs) of the hand. MATERIALS AND METHODS A retrospective multicenter trial of 29 patients with VMs primarily affecting the hand, including wrist, carpus, and/or fingers, treated by 81 percutaneous image-guided sclerotherapies using ethanol gel and/or polidocanol was performed. Clinical and imaging findings were assessed to evaluate clinical response, lesion size reduction, and complication rates. Substratification analysis was performed with respect to the Puig's classification, the sclerosing agent, the injected volume of the sclerosant, and to previously performed treatments. RESULTS The mean number of procedures per patient was 2.8 (± 2.2). Last follow-up (mean = 9.2~months) revealed a partial relief of symptoms in 78.9% (15/19), while three patients (15.8%) presented symptom-free and one patient (5.3%) with no improvement. Post-treatment imaging revealed an overall objective response rate of 88.9%. Early post-procedural complications occurred after 5/81 sclerotherapies (6.2%) and were entirely resolved by conservative means. Type of VM (Puig's classification) as well as sclerosing agent had no impact on clinical response (p = 0.85, p = 0.11) or complication rates (p = 0.66, p = 0.69). The complication rates were not associated with the sclerosant volume injected (p = 0.76). In addition, no significant differences in clinical success (p = 0.11) or complication rates (p = 0.89) were detected when comparing patients with history of previous treatments compared to therapy-naive patients. CONCLUSION Percutaneous sclerotherapy is both safe and effective for treating VMs of the hand. Even patients with history of previous treatments benefit from further sclerotherapy showing similar low complication rates to therapy-naive patients. LEVEL OF EVIDENCE Level 4, Retrospective study

Cost-Effectiveness Analysis of Local Treatment in Oligometastatic Disease

Background: In certain malignancies, patients with oligometastatic disease benefit from radical ablative or surgical treatment. The SABR-COMET trial demonstrated a survival benefit for oligometastatic patients randomized to local stereotactic ablative radiation (SABR) compared to patients receiving standard care (SC) alone. Our aim was to determine the cost-effectiveness of SABR. Materials and Methods: A decision model based on partitioned survival simulations estimated costs and quality-adjusted life years (QALY) associated with both strategies in a United States setting from a health care perspective. Analyses were performed over the trial duration of six years as well as a long-term horizon of 16 years. Model input parameters were based on the SABR-COMET trial data as well as best available and most recent data provided in the published literature. An annual discount of 3% for costs was implemented in the analysis. All costs were adjusted to 2019 US Dollars according to the United States Consumer Price Index. SABR costs were reported with an average of $11,700 per treatment. Deterministic and probabilistic sensitivity analyses were performed. Incremental costs, effectiveness, and cost-effectiveness ratios (ICER) were calculated. The willingness-to-pay (WTP) threshold was set to$100,000/QALY. Results: Based on increased overall and progression-free survival, the SABR group showed 0.78 incremental QALYs over the trial duration and 1.34 incremental QALYs over the long-term analysis. Treatment with SABR led to a marginal increase in costs compared to SC alone (SABR: $304,656; SC:$303,523 for 6 years; ICER $1,446/QALY and SABR:$402,888; SC: $350,708 for long-term analysis; ICER$38,874/QALY). Therapy with SABR remained cost-effective until treatment costs of $88,969 over the trial duration (i.e. 7.6 times the average cost). Sensitivity analysis identified a strong model impact for ongoing annual costs of oligo- and polymetastatic disease states. Conclusion: Our analysis suggests that local treatment with SABR adds QALYs for patients with certain oligometastatic cancers and represents an intermediate- and long-term cost-effective treatment strategy

An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology

We study the IR-through-UV interstellar extinction curves towards 328 Galactic B and late-O stars. We use a new technique which employs stellar atmosphere models in lieu of unreddened "standard" stars. This technique is capable of virtually eliminating spectral mismatch errors in the curves. It also allows a quantitative assessment of the errors and enables a rigorous testing of the significance of relationships between various curve parameters, regardless of whether their uncertainties are correlated. Analysis of the curves gives the following results: (1) In accord with our previous findings, the central position of the 2175 A extinction bump is mildly variable, its width is highly variable, and the two variations are unrelated. (2) Strong correlations are found among some extinction properties within the UV region, and within the IR region. (3) With the exception of a few curves with extreme (i.e., large) values of R(V), the UV and IR portions of Galactic extinction curves are not correlated with each other. (4) The large sightline-to-sightline variation seen in our sample implies that any average Galactic extinction curve will always reflect the biases of its parent sample. (5) The use of an average curve to deredden a spectral energy distribution (SED) will result in significant errors, and a realistic error budget for the dereddened SED must include the observed variance of Galactic curves. While the observed large sightline-to-sightline variations, and the lack of correlation among the various features of the curves, make it difficult to meaningfully characterize average extinction properties, they demonstrate that extinction curves respond sensitively to local conditions. Thus, each curve contains potentially unique information about the grains along its sightline.Comment: To appear in the Astrophysical Journal, Part 1, July 1, 2007. Figures and Tables which will appear only in the electronic version of the Journal can be obtained via anonymous ftp from ftp://ftp.astronomy.villanova.edu . After logging in, change directories to "fitz/FMV_EXTINCTION". A README file describes the various files present in the director