Incorporating collisions and resistance into the transition from field emission to the space charge regime

Advancements in microelectromechanical systems (MEMS) and microplasmas, particularly with respect to applications in combustion and biotechnology, motivate studies into microscale gas breakdown to enable safe system design and implementation. Breakdown at microscale deviates from that predicted by Paschen’s law due to field emission—the stripping of electrons from the cathode in the presence of strong surface field—and follows the Fowler-Nordheim (FN) law. As injected current increases at this length scale, electrons accumulate in the gap and FN electron emission becomes space charge limited, leading to the Child-Langmuir (CL) law at vacuum and the Mott-Gurney (MG) law at high pressure. While theoretical studies link CL to FN and CL to MG, none links all three to simultaneously assess the importance of pressure and external resistance (perturbation) on electron emission. This study extends existing theory to elucidate the transition between these regimes as a function of applied voltage, gap distance, electron mobility, and external resistance, and in particular, derives asymptotic equations illustrating the transitions between the three. It also demonstrates the presence of a triple point, where one theoretically encounters FN, CL, and MG at once, and characterizes the importance of gap pressure and distance on these regimes, especially when MG dominates at non-vacuum pressures. The sensitivity of the triple point to external resistance, representative of the effects of perturbations in system parameters on electron emission, receives special attention

Developmenting mathematical and algorithmic providing and software grid-system

Дипломна робота присвячена розробці математичної моделі та програмного забезпечення грід-системи для виконання високонавантажених обчислень. У ході викладу проводиться аналіз способів зберігання даних, протоколів взаємодії та архітектурних рішень. Обгрунтовується вибір мікросервісного підходу для створення запропонованої моделі програмного продукту. Проводиться аналіз проблематики високонавантажених обчислень та способів їх вирішення, збереження даних та побудови грід-систем.Graduate work deals with developmenting mathematical model and software Grid-system to perform heavy computing. During the presentation analyzes the methods of data storage, interaction protocols and architectural solutions. Substantiates the choice of micro-service approach proposed model for creating software. Evaluated problems of the heavy computing solutions, data storage and building Grid systems

Emergency Department and Radiological Cost of Delayed Diagnosis of Cannabinoid Hyperemesis.

Background. Chronic cannabis use has become prevalent with decriminalization, medical prescription, and recreational legalization in numerous US states. With this increasing incidence of chronic cannabis use a new clinical syndrome has become apparent in emergency departments and hospitals across the country, termed Cannabinoid Hyperemesis (CH). CH has been described as cyclical vomiting and abdominal pain in the setting of chronic cannabis use, which is often temporarily relieved by hot showers. CH presents a diagnostic challenge to clinicians who do not have a high clinical suspicion for the syndrome and can result in high costs and resource utilization for hospitals and patients. This study investigates the expenditures associated with delayed CH evaluation and delayed diagnosis. Methods. This is a retrospective observational study of 17 patients diagnosed with CH at three medical centers in the United States from 2010 to 2015, consisting of two academic centers and a community hospital. Emergency department (ED) costs were calculated and analyzed for patients eventually diagnosed with CH. Results. For the 17 patients treated, the total cost for combined ED visits and radiologic evaluations was an average of $76,920.92 per patient. On average these patients had 17.9 ED visits before the diagnosis of CH was made. Conclusion. CH provides a diagnostic challenge to clinicians without a high suspicion of the syndrome and may become increasingly prevalent with current trends toward cannabis legalization. The diagnosis of CH can be made primarily through a thorough history and physical examination. Awareness of this syndrome can save institutions money, prevent inappropriate utilization of healthcare resources, and save patients from unnecessary diagnostic tests

Representation of women in sport sciences research, publications, and editorial leadership positions: are we moving forward?

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Elena Martinez-Rosales was supported by the Spanish Ministry of Education (FPU18/01107) . Alba Hernandez-Martinez was supported by the Plan Propio, Gerty Cori program from the University of Almeria, Spain. Irene Esteban-Cornejo was supported by the Spanish Ministry of Economy and Competitiveness (RTI2018-095284-J-100) and the Spanish Ministry of Science and Innovation (RYC2019-027287-I) . Alberto Soriano-Maldonado was supported by the Spanish Ministry of Science, Innovation and Universities (ref. RTI2018-093302-A-I00) .Objectives: We determined the representation of women in sport sciences research leadership by assessing the proportion of women in (i) leading authorship positions of randomized controlled trials (RCTs) published from January 2000 to September 2020 in sport sciences journals and (ii) editorial boards of these journals as of September 2020. Design: Review. Methods: We searched PubMed for RCTs published from January 1, 2000, to September 1, 2020, in a representative sample of the top sport sciences journals and identified the sex of first and senior authors through photographs, sex pronouns, Google Scholar, ResearchGate, institutional, or other profiles. This strategy was also used to identify the sex of the editorial board members from the selected journals. Results: A total of 4841 articles published in 14 journals, and 1418 editors, were analyzed. The average proportions of female first and senior authorship were 24.8% and 16.8%, respectively. The percentage of female first authorship increased by ~0.5% annually (β=0.702; B=0.46, 95% CI=0.24 to 0.68, p < 0.001) from2000 to 2020, while the percentage of female senior authorship did not change over time (β = 0.274; B = 0.15, 95% CI = −0.102 to 0.398, p = 0.230). Among the editorial boards' positions, 19.7% were occupied by women. None of the editors-in-chief of the selected journals were women. Conclusions:Women are markedly underrepresented in leading authorship and editorial board positions in sport sciences, despite a ~0.5% annual increase in female first authorship in the past two decades. The mechanisms underlying these findings and the actions needed to reduce potential gender inequalities warrant further research.Spanish Government FPU18/01107University of Almeria, SpainSpanish Ministry of Economy and Competitiveness RTI2018-095284-J-100Spanish Government RYC2019-027287-ISpanish Ministry of Science, Innovation and Universities RTI2018-093302-A-I0

Bibliometric and authorship trends over a 30 year publication history in two representative US sports medicine journals

Bibliometric studies are important to understand changes and improvement opportunities in academia. This study compared bibliometric trends for two major sports medicine/arthroscopy journals, the American Journal of Sports Medicine® (AJSM®) and Arthroscopy® over the past 30 years. Trends over time and comparisons between both journals were noted for common bibliometric variables (number of authors, references, pages, citations, and corresponding author position) as well as author gender and continental origin. Appropriate statistical analyses were performed. A p < 0.001 was considered statistically significant. One representative year per decade was used. There were 814 manuscripts from AJSM® and 650 from Arthroscopy®. For AJSM® the number of manuscripts steadily increased from 86 in 1986 to 350 in 2016; for Arthroscopy® the number of manuscripts increased from 73 in 1985/1986, to 267 in 2006, but then dropped to 229 in 2016. There were significant increases in all bibliometric variables, except for the number of citations which decreased in Arthroscopy®. There were significant differences in manuscript region of origin by journal (p = 0.000002). Arthroscopy® had a greater percentage of manuscripts from Asia than AJSM® (19.3% vs 11.5%) while AJSM® had a greater percentage from North America (70.3% vs 59.2%); both journals had similar percentages from Europe (18.2% for AJSM® and 21.6% for Arthroscopy®). For AJSM® the average percentage of female first authors was 13.3%, increasing from 4.7% in 1986 to 19.3% in 2016; the average percentage of female corresponding authors was 7.3%. For Arthroscopy®, the average percentage of female first authors was 8.1%, increasing from 2.8% in 1985/1986 to 15.7% in 2016 (p = 0.00007). In conclusion, AJSM® and Arthroscopy® showed an increase in most variables analyzed. Although Arthroscopy® is climbing at a higher rate than AJSM® for female authors, AJSM® has an overall greater percentage of female authors

Pathologic fracture and hardware failure in Streptococcus anginosus femoral osteomyelitis: Case report

Introduction: Pathologic fracture of the femur due to Streptococcus anginosus osteomyelitis has rarely been described. With limited evidence for treating S. anginosus osteomyelitis, the orthopaedic surgeon is presented with a difficult treatment decision at index presentation. Presented here is a case of failed conservative management, diagnostic dilemma, failed hardware stabilization, and definitive surgical treatment resulting in good clinical outcome. Case presentation: A 69-year-old male experienced acute right thigh pain, edema, and erythema after dental treatment 17 days prior. He was diagnosed with right femoral diaphyseal osteomyelitis and Brodie's abscess. Blood cultures grew S. anginosus, but all site-specific tissue cultures resulted negative. Initial management consisted of intravenous antibiotic therapy and percutaneous abscess drainage. Months later, the patient sustained a displaced pathologic fracture of the diaphyseal femur and there was concern for neoplasm, but biopsies were negative. Stabilization was attempted with a lateral plate and screws. This hardware catastrophically failed in the setting of an oligotrophic femoral nonunion. Ultimately, the patient was successfully treated with an intramedullary nail coated with antibiotic-impregnated cement. Twelve months later, the patient achieved clinical and radiographic healing with no evidence of relapse of his osteomyelitis. Clinical discussion: Conservative management of S. anginosus femoral osteomyelitis was inadequate and corroborates the existing literature. S. anginosus osteomyelitis and pyomyositis may be most optimally treated aggressively with early surgical intervention. Conclusion: Early surgical debridement and stabilization of the compromised bone with an antibiotic coated intramedullary nail following medullary reaming may prevent pathologic fracture, eradicate infection, and achieve predictable outcomes

The effect of marrow secretome and culture environment on the rate of metastatic breast cancer cell migration in two and three dimensions

Metastasis is responsible for over 90% of cancer-related deaths, and bone is the most common site for breast cancer metastasis. Metastatic breast cancer cells home to trabecular bone, which contains hematopoietic and stromal lineage cells in the marrow. As such, it is crucial to understand whether bone or marrow cells enhance breast cancer cell migration toward the tissue. To this end, we quantified the migration of MDA-MB-231 cells toward human bone in two- and three-dimensional (3D) environments. First, we found that the cancer cells cultured on tissue culture plastic migrated toward intact trabecular bone explants at a higher rate than toward marrow-deficient bone or devitalized bone. Leptin was more abundant in conditioned media from the cocultures with intact explants, while higher levels of IL-1β, IL-6, and TNFα were detected in cultures with both intact bone and cancer cells. We further verified that the cancer cells migrated into bone marrow using a bioreactor culture system. Finally, we studied migration toward bone in 3D gelatin. Migration speed did not depend on stiffness of this homogeneous gel, but many more dendritic-shaped cancer cells oriented and migrated toward bone in stiffer gels than softer gels, suggesting a coupling between matrix mechanics and chemotactic signals