Modeling Vacuum Arcs

We are developing a model of vacuum arcs. This model assumes that arcs develop as a result of mechanical failure of the surface due to Coulomb explosions, followed by ionization of fragments by field emission and the development of a small, dense plasma that interacts with the surface primarily through self sputtering and terminates as a unipolar arc capable of producing breakdown sites with high enhancement factors. We have attempted to produce a self consistent picture of triggering, arc evolution and surface damage. We are modeling these mechanisms using Molecular Dynamics (mechanical failure, Coulomb explosions, self sputtering), Particle-In-Cell (PIC) codes (plasma evolution), mesoscale surface thermodynamics (surface evolution), and finite element electrostatic modeling (field enhancements). We can present a variety of numerical results. We identify where our model differs from other descriptions of this phenomenon.Comment: 4 pages, 5 figure

Investigation on the Structural and Optical Properties of Thermally Evaporated Indium Selenide Compound Material for Solar Cell Application

In2Se3 thin films with different thicknesses have been deposited by thermal evaporation method on glass substrate under vacuum pressure of 10-6 Torr. Structural Properties of these films were studied by different analytical techniques. X- ray diffraction revealed as deposited films have amorphous nature and annealing effect enhanced crystalline structure. Structural studies by XRD results showed the polycrystalline nature of the films. The Full Width at Half Maximum (FWHM) values were observed from the XRD pattern and used to evaluate the microstructural parameters like crystallite size, strain, dislocation density. The optical absorption spectra of In2Se3 films were studied in the wavelength region of 250–2500 nm. The optical properties show that the band gap (Eg) values vary from 2.5 to 3.34 eV as an-nealing temperature varies from 150 to 350C. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3513

Electrodeposition of Sn, Se, SnSe and the material properties of SnSe films

Tin sulphide (SnS) films have been electrodeposited and the materials properties are reported, The potential-pH diagram of Sn and S in aqueous medium are superimposed to obtain the common immunity domains which predicts a pH value 1.5 and deposition potential of ·1.0 VseE for the stoichiometric deposition. Films are cathodically deposited on 5002 coated conducting glass substrates at bath temperatures 303-353 K. XRD studies show the polycrystalline nature with orthorhombic structure. The optical band gap of the snS film is 1.1 eV from the absorption studies. ESCA spectrum confirms the presence of Sn and S on the grey black sample. Uniform, smooth and pin hole free surface morphology is observed by SEM

Proximal femur fractures - effect of preoperative mental status of patients on postoperative mobility of patients

Background: In the elderly population, proximal femur fractures are most common which can result in increase of morbidity and mortality. Pre and postoperative mobility patterns, also depends upon the Mental Status of the patient. Incidence of Mental health disorders of patient can increases with age and co morbidities. The aim of the study was to evaluate the effect and relationship of preoperative mental status, on postoperative mobility in proximal femur fracture patients. On null hypothesis; there exists no co-relation between pre-operative mental status on pre and postoperative mobility those had surgery for proximal femur fractures.Methods: This is a retrospective study, carried out during the period of 14th March, 2016 to 14th March, 2017 at BIRRD (T) Hospital. All the patients who underwent proximal femur fracture surgeries were included in the study. Patients were evaluated for Abbreviated Mental Score Test pre-operatively. Mobility patterns were before injury and after surgery evaluated in patients with proximal femur fractures. Postoperatively patients were followed up to one year.Results: 50 patients were included into the study, where 12 patients could not present to follow-up due to various reasons, thus we have complete data of 38 patients. There is significant reduction in mobility status of individuals i.e. from 6.18 (preoperative pre fracture mobility) to 5.36 (postoperative mobility). Average abbreviated mental test score is 7.55. There exists a correlation between the variables.Conclusions: Null hypothesis remains rejected. There is statistically significant relationship between the variables (pre and postoperative mobility, and abbreviated mental test score), which appears to be positive correlation

The incidence of symptomatic deep vein thrombosis and pulmonary embolism, following THA in patients, with postoperative chemoprophylaxis in Indian population

Background: Deep vein thrombosis (DVT) and pulmonary embolism (PE) can occur in patients after elective total hip arthroplasties (THA). Indian population appears to have low incidence of DVT and PE in comparison with Western population due to difference in ethnicity, genetic make-up, social life styles. The study intends to find the incidence of symptomatic DVT and PE in postoperative THA patients. The aim of the study was to study the incidence of symptomatic DVT and PE, in post-THA patients in Indian Population.Methods: Retrospective study conducted from 1st January, 2017 to 31st July, 2018 in BIRRD (T) Hospital. All patients who underwent THA are included, after fulfilling inclusion and exclusion criteria. Patients were evaluated for symptoms during the hospital stay and after discharge for 3 Months.Results: Total number of patients who had THA were 447 (n=447). The symptomatic DVT was found in 1 (n=1) patient. He developed DVT (n=1) during the study period, in first 48 hours postoperatively and recovered with ICU management. The same patient showed symptoms of PE but recovered fully. All patients were on a prophylactic regimen.Conclusions: Our results suggest incidence of DVT and PE are low in the Indian population with a prophylactic regimen

Modeling RF breakdown arcs

We describe breakdown in 805 MHz rf accelerator cavities in terms of a number of self-consistent mechanisms. We divide the breakdown process into three stages: (1) we model surface failure using molecular dynamics of fracture caused by electrostatic tensile stress, (2) we model the ionization of neutrals responsible for plasma initiation and plasma growth using a particle-in-cell code, and (3) we model surface damage by assuming a process similar to unipolar arcing. We nd that the cold, dense plasma in contact with the surface produces very small Debye lengths and very high electric fields over a large area, consistent with unipolar arc behavior, although unipolar arcs are strictly de ned with equipotential boundaries. These high elds produce strong erosion mechanisms, primarily self-sputtering, compatible with the crater formation that we see. We use the OOPIC model to estimate very high surface electric elds in the dense plasma and measure these elds using electrohydrodynamic arguments to relate the dimensions of surface damage with the applied electric eld. We also present a geometrical explanation of the large enhancement factors of field emitters.This is consistent with the apparent absence of whiskers on surfaces exposed to high elds. The enhancement factors we derive, when combined with Fowler-Nordheim analysis, produce a consistent picture of breakdown and eld emission from surfaces at local elds of 7{10 GV/m. We show that the plasma growth rates we obtain from OOPIC are consistent with growth rates of the cavity shorting currents using x-ray measurements. We believe the general picture presented here for rf breakdown arcs should be directly applicable to a larger class of vacuum arcs. Results from the plasma simulation are included as a guide to experimental veri cation of this model

Modeling 21st century project teams: docking workflow and knowledge network computational models

This paper reports on an attempt to integrate and extend two established computational organizational models\u2014SimVision\uae and Blanche\u2014to examine the co-evolution of workflow and knowledge networks in 21st century project teams. Traditionally, workflow in project teams has been modeled as sets of sequential and/or parallel activities each assigned to a responsible participant, organized in a fixed structure. In the spirit of Jay Galbraith\u2019s (1973) information processing view of organizations, exceptions\u2014situations in which participants lack the required knowledge to complete a task\u2014are referred up the hierarchy for resolution. However, recent developments in digital technologies have created the possibility to design project teams that are more flexible, self-organizing structures, in which exceptions can be resolved much more flexibly through knowledge networks that extend beyond the project or even the company boundaries. In addition to seeking resolution to exceptions up the hierarchy, members of project teams may be motivated to retrieve the necessary expertise from other knowledgeable members in the project team. Further, they may also retrieve information from non-human agents, such as knowledge repositories or databases, available to the project team. Theories, such as Transactive Memory, Public Goods, Social Exchange and Proximity may guide their choice of retrieving information from a specific project team member or database. This paper reports on a \u201cdocked\u201d computational model that can be used to generate and test hypotheses about the co-evolution of workflow and knowledge networks of these 21st century project teams in terms of their knowledge distribution and performance. The two computational models being docked are SimVision (Jin & Levitt, 1999) which has sophisticated processes to model organizations executing project-oriented workflows, and Blanche (Hyatt, Contractor, & Jones, 1997), a multiagent computational network environment, which models multitheoretical mechanisms for the retrieval and allocation of information in knowledge networks involving human and non-human agents. This paper was supported in part by a grant from the U.S. National Science Foundation for the project \u201cCo-Evolution of Knowledge Networks and 21st Century Organizational Forms (IIS- 9980109)

Mannose binding lectin is required for alphavirus-induced arthritis/myositis

Mosquito-borne alphaviruses such as chikungunya virus and Ross River virus (RRV) are emerging pathogens capable of causing large-scale epidemics of virus-induced arthritis and myositis. The pathology of RRV-induced disease in both humans and mice is associated with induction of the host inflammatory response within the muscle and joints, and prior studies have demonstrated that the host complement system contributes to development of disease. In this study, we have used a mouse model of RRV-induced disease to identify and characterize which complement activation pathways mediate disease progression after infection, and we have identified the mannose binding lectin (MBL) pathway, but not the classical or alternative complement activation pathways, as essential for development of RRV-induced disease. MBL deposition was enhanced in RRV infected muscle tissue from wild type mice and RRV infected MBL deficient mice exhibited reduced disease, tissue damage, and complement deposition compared to wild-type mice. In contrast, mice deficient for key components of the classical or alternative complement activation pathways still developed severe RRV-induced disease. Further characterization of MBL deficient mice demonstrated that similar to C3(-/-) mice, viral replication and inflammatory cell recruitment were equivalent to wild type animals, suggesting that RRV-mediated induction of complement dependent immune pathology is largely MBL dependent. Consistent with these findings, human patients diagnosed with RRV disease had elevated serum MBL levels compared to healthy controls, and MBL levels in the serum and synovial fluid correlated with severity of disease. These findings demonstrate a role for MBL in promoting RRV-induced disease in both mice and humans and suggest that the MBL pathway of complement activation may be an effective target for therapeutic intervention for humans suffering from RRV-induced arthritis and myositis.This work was supported by NIH/NIAMS R01 AR 047190 awarded to MTH