The efficient calculation of the transport properties of a dilute gas to a prescribed accuracy

Numerical techniques for minimizing computation time for determining transport properties of dilute ga

Rocketdyne PSAM: In-house enhancement/application

The development was initiated of the Probabilistic Design Analysis (PDA) Process for rocket engines. This will enable engineers a quantitative assessment of calculated reliability during the design process. The PDA will help choose better designs, make them more robust, and help decide on critical tests to help demonstrate key reliability issues to aid in improving the confidence of the engine capabilities. Rockedyne's involvement with the Composite Loads Spectra (CLS) and Probabilistic Structural Analysis Methodology (PSAM) contracts started this effort and are key elements in the on-going developments. Internal development efforts and hardware applications complement and extend the CLS and PSAM efforts. The completion of the CLS option work and the follow-on PSAM developments will also be integral parts of this methodology. A brief summary of these efforts is presented

Dispersion Study of a Broadband Terahertz Focusing Reflecting Metasurface for 6G Wireless Communication

In 6G wireless communications, functional terahertz reflecting metasurfaces are expected to play increasingly important roles such as beamforming and beamsteering. This paper demonstrates the design of a functional and efficient beamforming metasurface in the burgeoning D-band (0.11-0.17~THz). In addition to achieving broadband operation (0.135-0.165~THz), this design is polarization-maintaining, diffraction limited, simple in design, exhibits 64.1\% broadband efficiency (1.9 dB insertion loss) and 20\% fractional bandwidth. Despite being formed by an array of highly dispersive resonators, the metasurface exhibits very low temporal dispersion, which avoids pulse reshaping and its consequent limitations on achievable data rate. The design and performance of the focusing reflector are presented followed by a group delay and group delay dispersion analysis revealing that a 2.83\% temporal broadening of the pulse is observed at the focus

The evaluation of definite integrals by interval subdivision

Algorithm for efficient evaluation of badly behaved definite integrals to prescribed accuracy by concentrating abscissas near regions of most irregularity in integran

A simple probabilistic construction yielding generalized entropies and divergences, escort distributions and q-Gaussians

We give a simple probabilistic description of a transition between two states which leads to a generalized escort distribution. When the parameter of the distribution varies, it defines a parametric curve that we call an escort-path. The R\'enyi divergence appears as a natural by-product of the setting. We study the dynamics of the Fisher information on this path, and show in particular that the thermodynamic divergence is proportional to Jeffreys' divergence. Next, we consider the problem of inferring a distribution on the escort-path, subject to generalized moments constraints. We show that our setting naturally induces a rationale for the minimization of the R\'enyi information divergence. Then, we derive the optimum distribution as a generalized q-Gaussian distribution

Bridge over Olduvai Gorge: Capacity building and conservation of lithics and fossils

This paper explores decision-making processes involved in the conservation of lithics and fossils excavated at Olduvai Gorge, Tanzania. The site is renowned for discoveries of early humans from the Palaeolithic period, lithics and fossils that document the evolutionary history of humans, vertebrate fauna and their environment over the last two million years. Excavated specimens are treated in situ, at the field laboratory and at the UCL Institute of Archaeology in London. Factors such as accessibility, ease of transportation and preparation, disposal, Tg and toxicity of resins, and ease of re-treatability are considered to decide what can be used in treatments and how. Frequently used materials include Paraloid B-44 and cyclododecane for temporary consolidation and Paraloid B-44 for adhesion and gap-filling. We have found that, in such complex contexts, the more one engages with colleagues across the disciplines and local community groups, the smoother, stronger and more sustainable one’s efforts become

Cyclic nitroxides inhibit the toxicity of nitric oxide-derived oxidants: mechanisms and implications

The substantial therapeutic potential of tempol (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy) and related cyclic nitroxides as antioxidants has stimulated innumerous studies of their reactions with reactive oxygen species. In comparison, reactions of nitroxides with nitric oxide-derived oxidants have been less frequently investigated. Nevertheless, this is relevant because tempol has also been shown to protect animals from injuries associated with inflammatory conditions, which are characterized by the increased production of nitric oxide and its derived oxidants. Here, we review recent studies addressing the mechanisms by which cyclic nitroxides attenuate the toxicity of nitric oxidederived oxidants. As an example, we present data showing that tempol protects mice from acetaminophen-induced hepatotoxicity and discuss the possible protection mechanism. In view of the summarized studies, it is proposed that nitroxides attenuate tissue injury under inflammatory conditions mainly because of their ability to react rapidly with nitrogen dioxide and carbonate radical. In the process the nitroxides are oxidized to the corresponding oxammonium cation, which, in turn, can be recycled back to the nitroxides by reacting with upstream species, such as peroxynitrite and hydrogen peroxide, or with cellular reductants. An auxiliary protection mechanism may be down-regulation of inducible nitric oxide synthase expression. The possible therapeutic implications of these mechanisms are addressed.O considerável potencial terapêutico de tempol (4-hidroxi-2,2, 6,6-tetrametil-1piperiniloxila) e nitróxidos cíclicos relacionados como antioxidantes tem estimulado inúmeros estudos de suas reações com espécies reativas derivadas de oxigênio. Em comparação, as reações de nitróxidos com oxidantes derivados do óxido nítrico têm sido investigadas menos frequentemente. Todavia, essas reações são relevantes porque o tempol é também capaz de proteger animais de injúrias associadas a condições inflamatórias, as quais são caracterizadas por uma aumentada produção de óxido nítrico e derivados oxidantes. Aqui, discutimos estudos recentes abordando os mecanismos pelos quais nitróxidos cíclicos atenuam a toxicidade de oxidantes derivados do óxido nítrico. Como um exemplo, apresentamos dados que demonstram que o tempol protege camundongos do dano hepatotóxico promovido por altas doses de acetaminofeno e discutimos o possível mecanismo de proteção. Com base nos estudos sumarizados, é proposto que nitróxidos atenuam a injúria tecidual em condições inflamatórias devido principalmente a sua capacidade de reagir rapidamente com ambos, dióxido de nitrogênio e radical carbonato. Em conseqüência, os nitróxidos são oxidados ao cátion oxamônio correspondente, o qual, por sua vez, pode ser reciclado ao nitróxido através de reações com espécies precursoras, como peroxinitrito e peróxido de hidrogênio, ou com redutores celulares. Um possível mecanismo auxiliar de proteção é a regulação negativa da expressão da sintase do óxido nítrico induzível. As possíveis implicações terapêuticas desses mecanismos são abordadas.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq