Laser-induced phase separation of silicon carbide

Understanding the phase separation mechanism of solid-state binary compounds induced by laser-material interaction is a challenge because of the complexity of the compound materials and short processing times. Here we present xenon chloride excimer laser-induced melt-mediated phase separation and surface reconstruction of single-crystal silicon carbide and study this process by high-resolution transmission electron microscopy and a time-resolved reflectance method. A single-pulse laser irradiation triggers melting of the silicon carbide surface, resulting in a phase separation into a disordered carbon layer with partially graphitic domains (???2.5 nm) and polycrystalline silicon (???5 nm). Additional pulse irradiations cause sublimation of only the separated silicon element and subsequent transformation of the disordered carbon layer into multilayer graphene. The results demonstrate viability of synthesizing ultra-thin nanomaterials by the decomposition of a binary system.open

International medical graduates in family medicine in the United States of America: an exploration of professional characteristics and attitudes

BACKGROUND: The number of international medical graduates (IMGs) entering family medicine in the United States of America has steadily increased since 1997. Previous research has examined practice locations of these IMGs and their role in providing care to underserved populations. To our knowledge, research does not exist comparing professional profiles, credentials and attitudes among IMG and United States medical graduate (USMG) family physicians in the United States. The objective of this study is to determine, at the time when a large influx of IMGs into family medicine began, whether differences existed between USMG and IMG family physicians in regard to personal and professional characteristics and attitudes that may have implications for the health care system resulting from the increasing numbers of IMGs in family medicine in the United States. METHODS: This is a secondary data analysis of the 1996–1997 Community Tracking Study (CTS) Physician Survey comparing 2360 United States medical graduates and 366 international medical graduates who were nonfederal allopathic or osteopathic family physicians providing direct patient care for at least 20 hours per week. RESULTS: Compared to USMGs, IMGs were older (p < 0.001) and practised in smaller (p = 0.0072) and younger practices (p < 0.001). Significantly more IMGs practised in metropolitan areas versus rural areas (p = 0.0454). More IMG practices were open to all new Medicaid (p = 0.018) and Medicare (p = 0.0451) patients, and a greater percentage of their revenue was derived from these patients (p = 0.0020 and p = 0.0310). Fewer IMGs were board-certified (p < 0.001). More IMGs were dissatisfied with their overall careers (p = 0.0190). IMGs and USMGs did not differ in terms of self-rated ability to deliver high-quality care to their patients (p = 0.4626). For several of the clinical vignettes, IMGs were more likely to order tests, refer patients to specialists or require office visits than USMGs. CONCLUSION: There are significant differences between IMG and USMG family physicians' professional profiles and attitudes. These differences from 1997 merit further exploration and possible follow-up, given the increased proportion of family physicians who are IMGs in the United States

Carbon related defects in irradiated silicon revisited

Electronic structure calculations employing hybrid functionals are used to gain insight into the interaction of carbon (C) atoms, oxygen (O) interstitials, and self-interstitials in silicon (Si). We calculate the formation energies of the C related defects C(i)(Si(I)), C(i)O(i), C(i)C(s), and C(i)O(i)(Si(I)) with respect to the Fermi energy for all possible charge states. The C(i)(Si(I))(2+) state dominates in almost the whole Fermi energy range. The unpaired electron in the C(i)O(i)(+) state is mainly localized on the C interstitial so that spin polarization is able to lower the total energy. The three known atomic configurations of the C(i)C(s) pair are reproduced and it is demonstrated that hybrid functionals yield an improved energetic order for both the A and B-types as compared to previous theoretical studies. Different structures of the C(i)O(i)(Si(I)) cluster result for positive charge states in dramatically distinct electronic states around the Fermi energy and formation energies

In pursuit of P2X3 antagonists: novel therapeutics for chronic pain and afferent sensitization

Treating pain by inhibiting ATP activation of P2X3-containing receptors heralds an exciting new approach to pain management, and Afferent's program marks the vanguard in a new class of drugs poised to explore this approach to meet the significant unmet needs in pain management. P2X3 receptor subunits are expressed predominately and selectively in so-called C- and Aδ-fiber primary afferent neurons in most tissues and organ systems, including skin, joints, and hollow organs, suggesting a high degree of specificity to the pain sensing system in the human body. P2X3 antagonists block the activation of these fibers by ATP and stand to offer an alternative approach to the management of pain and discomfort. In addition, P2X3 is expressed pre-synaptically at central terminals of C-fiber afferent neurons, where ATP further sensitizes transmission of painful signals. As a result of the selectivity of the expression of P2X3, there is a lower likelihood of adverse effects in the brain, gastrointestinal, or cardiovascular tissues, effects which remain limiting factors for many existing pain therapeutics. In the periphery, ATP (the factor that triggers P2X3 receptor activation) can be released from various cells as a result of tissue inflammation, injury or stress, as well as visceral organ distension, and stimulate these local nociceptors. The P2X3 receptor rationale has aroused a formidable level of investigation producing many reports that clarify the potential role of ATP as a pain mediator, in chronic sensitized states in particular, and has piqued the interest of pharmaceutical companies. P2X receptor-mediated afferent activation has been implicated in inflammatory, visceral, and neuropathic pain states, as well as in airways hyperreactivity, migraine, itch, and cancer pain. It is well appreciated that oftentimes new mechanisms translate poorly from models into clinical efficacy and effectiveness; however, the breadth of activity seen from P2X3 inhibition in models offers a realistic chance that this novel mechanism to inhibit afferent nerve sensitization may find its place in the sun and bring some merciful relief to the torment of persistent discomfort and pain. The development philosophy at Afferent is to conduct proof of concept patient studies and best identify target patient groups that may benefit from this new intervention

Drug Resistance in Eukaryotic Microorganisms

Eukaryotic microbial pathogens are major contributors to illness and death globally. Although much of their impact can be controlled by drug therapy as with prokaryotic microorganisms, the emergence of drug resistance has threatened these treatment efforts. Here, we discuss the challenges posed by eukaryotic microbial pathogens and how these are similar to, or differ from, the challenges of prokaryotic antibiotic resistance. The therapies used for several major eukaryotic microorganisms are then detailed, and the mechanisms that they have evolved to overcome these therapies are described. The rapid emergence of resistance and the restricted pipeline of new drug therapies pose considerable risks to global health and are particularly acute in the developing world. Nonetheless, we detail how the integration of new technology, biological understanding, epidemiology and evolutionary analysis can help sustain existing therapies, anticipate the emergence of resistance or optimize the deployment of new therapies

Análise a longo prazo do tratamento conservador na doença de Legg-Calvé-Perthes Long-term analysis of a conservative approach in Legg-Clavé-Perthes disease

O objetivo do estudo é a análise a longo prazo de pacientes portadores da doença de Legg-Calvé-Perthes que foram tratados conservadoramente. Foram analisados 43 pacientes (49 quadris), na fase ativa da doença, radiograficamente segundo os critérios de Catterall e Herring, na época do diagnóstico, e os métodos Mose e Stulberg, na maturidade esquelética, e clinicamente segundo os critérios de Larson, ou escala de IOWA. O tempo de seguimento médio foi de 19 anos. Os pacientes foram divididos em dois grupos: grupo I, onde a carga foi liberada e grupo II restrição da deambulação. Na análise dos resultados obtidos segundo a escala de IOWA, não houve diferença estatística significante entre os dois grupos. Dentre os métodos empregados na fase ativa da doença, a classificação radiográfica segundo os critérios de Herring et al. foi aparentemente a que maior concordância apresentou com os resultados observados na classificação de Stulberg et al. Os autores concluem que os resultados avaliados pela escala de IOWA não se correlacionam com a gravidade do acometimento da doença e nem com a avaliação radiográfica na maturidade esquelética.<br>The objective of this study is the long-term analysis of patients with Legg-Calvé-Perthes disease who were treated using a conservative approach. Forty-three patients (forty-nine hips at disease’s active phase) were analyzed for x-ray imaging according to Catterall and Herring et al. criteria by the time of diagnosis and according to Mose and Stulberg methods by skeletal maturity phase, and, clinically, according to the Larson’s criteria or IOWA scale. The average follow-up was 19 years. Patients were divided into two groups: group I, where load was allowed, and group II, in which ambulation was restricted. By the analysis of results achieved according to IOWA scale, there was no statistically significant difference between both groups. Among the employed methods for the active phase of the disease, x-ray classification according to criteria by Herring et al. was the one mostly in accordance with the outcomes seen in Stulberg et al. classification. The authors conclude that the outcomes evaluated by IOWA scale are not correlated to the severity of the disease or to the x-ray evaluation in skeletal maturity phase