Molecular Dynamics of Solids at Constant Pressure and Stress Using Anisotropic Stochastic Cell Rescaling

Molecular dynamics simulations of solids are often performed using anisotropic barostats that allow the shape and volume of the periodic cell to change during the simulation. Most existing schemes are based on a second-order differential equation that might lead to undesired oscillatory behaviors and should not be used in the equilibration phase. We recently introduced stochastic cell rescaling, a first-order stochastic barostat that can be used for both the equilibration and production phases. Only the isotropic and semi-isotropic variants have been formulated and implemented so far. In this paper, we develop and implement the equations of motion of the fully anisotropic variant and test them on Lennard-Jones solids, ice, gypsum, and gold. The algorithm has a single parameter that controls the relaxation time of the volume, results in the exponential decay of correlation functions, and can be effectively applied to a wide range of systems

Stapled Porcine Pericardium Displays Lower Infectivity In Vitro Than Native and Sutured Porcine Pericardium.

Biological xenografts using tubulized porcine pericardium are an alternative to replace infected prosthetic graft. We recently reported an innovative technique using a stapled porcine pericardial bioconduit for immediate vascular reconstruction in emergency. The objective of this study is to compare the growth and adherence to grafts of bacteria and yeast incubated with stapled porcine pericardium, sutured or naked pericardium. One square centimeter of porcine pericardial patches, with or without staples or sutures, was incubated with 10 <sup>5</sup> colony forming units of Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans for 1, 6, and 24 h. The medium was collected to quantify planktonic microorganisms, while grafts were sonicated to quantify adherent microorganisms. Dacron and Dacron Silver were analyzed in parallel as synthetic reference prostheses. Stapled porcine pericardium reduced the growth and the adherence of E coli (2- to 30-fold; P < 0.0005), S aureus (11- to 1000-fold; P < 0.0006), S epidermidis (>500-fold; P < 0.0001), and C albicans (12- to 50-fold; P < 0.0001) when compared to medium alone (growth) and pericardium or Dacron (adherence). Native and sutured porcine pericardium interfered with the growth and the adherence of E coli and C albicans, and Dacron with that of S epidermidis. As expected, Dacron Silver was robustly bactericidal. Stapled porcine pericardium exhibited a lower susceptibility to infection by bacteria and yeasts in vitro when compared to the native and sutured porcine pericardium. Stapled porcine pericardium might be a good option for rapid vascular grafting without increasing infectivity

O surgimento das políticas de responsabilidade com consequências graves na formação de professores: Um estudo dos regulamentos propostos pelo Departamento de Educação dos EUA

Using a sociological framework this article explores the emergence and possible consequences of the 2015 U.S. Department of Education’s proposed federal regulatory policy on teacher education programs and alternative route providers. After describing the key features of the policy, we examine the research literature looking for evidence of the merits of accountability policies in improving teacher education and preparation quality and outcomes. Although there is some research evidence that increased accountability measures may indeed contribute to improving the quality and outcomes of teacher education and preparation, the conditions under which this happens are not straightforward. While the stated aim of the regulatory policy, to ultimately advance student learning, finds widespread support in the education community, research evidence points to a number of validity problems with the overall policy. Of particular concern is the policy’s attempts at establishing a direct link between teacher preparation and two of the regulations’ suggested outcomes, namely graduates’ employment and pupil achievement. The policy as conceived could negatively impact program norms and resources and undermine the development of teachers’ human, cultural, and social capital. We discuss the accreditation challenges that the policy is likely to confront and implications for the future of teacher education and preparation accountability.  Usando un marco conceptual sociológico este artículo explora el surgimiento y las posibles consecuencias de las políticas de reglamentación federal propuestas en 2015 por el Departamento de Educación de EE. UU sobre los programas de formación docente y sobre los modelos de formación alternativos. Después de describir las características claves de esas políticas, analizamos la literatura en busca de evidencia de los méritos de las políticas de rendición de cuentas en la mejora de la formación docente, la calidad de la preparación y sus resultados. Aunque existe alguna evidencia de que el aumento de las medidas de responsabilidad puede contribuir a la mejora de la calidad de la preparación docente, las condiciones en que esto sucede no son sencillas. Mientras que el objetivo declarado de la política, la mejora del aprendizaje de los estudiantes, tiene un amplio apoyo entre la comunidad educativa, las evidencias recogidas en esta investigación identifico una serie de problemas respecto a la validez de esta política. Una preocupación importante es acerca de los intentos de establecer un vínculo directo entre formación docente e indicadores de empleo y rendimiento de los alumnos. Tal como está concebida esta política podría impactar negativamente las normas y recursos del programa y socavar el desarrollo de los docentes en términos de recursos humanos, culturales, y de capital social. Discutimos los desafíos de la acreditación que probablemente esta política enfrentara y las implicaciones para el futuro de las políticas de rendición de cuentas en la mejora de la formación docente.Usando uma base conceitual sociológica este artigo explora a ascensão e as possíveis consequências das políticas de regulação federais em 2015 propostas pelo Departamento de Educação dos Estados Unidos para os programas de formação docente e de modelos alternativos de formação. Depois de descrever as principais características dessas políticas, analisamos a literatura  procurando evidências sobre o mérito das políticas de responsabilização na melhora da formação de professores, a qualidade da preparação e os resultados. Embora encontramos algumas evidências de que as medidas de prestação de contas poderiam contribuir para melhorar a qualidade, os resultados da educação e da formação de professores, as condições em que isso acontece não são simples. Embora a meta declarada dessas políticas,  a melhoria dos aprendizagem dos alunos, tem amplo apoio entre a comunidade educativa, as provas recolhidas nesta investigação identificaram uma série de problemas relacionados com a validade desta política. Uma grande preocupação é sobre as tentativas de estabelecer uma ligação direta entre a formação de professores e indicadores de emprego e desempenho dos alunos. Como esta formulada esta política poderia impactar negativamente as regras e os recursos dos programa e prejudicar o desenvolvimento dos professores em termos de recursos humanos, culturais e capital social. Discutimos os desafios de credenciamento que esta política deverá enfrentar e as implicações para o futuro das políticas de responsabilidade na melhora da formação de professores