An assessment and application of turbulence models for hypersonic flows

The current approach to the Accurate Computation of Complex high-speed flows is to solve the Reynolds averaged Navier-Stokes equations using finite difference methods. An integral part of this approach consists of development and applications of mathematical turbulence models which are necessary in predicting the aerothermodynamic loads on the vehicle and the performance of the propulsion plant. Computations of several high speed turbulent flows using various turbulence models are described and the models are evaluated by comparing computations with the results of experimental measurements. The cases investigated include flows over insulated and cooled flat plates with Mach numbers ranging from 2 to 8 and wall temperature ratios ranging from 0.2 to 1.0. The turbulence models investigated include zero-equation, two-equation, and Reynolds-stress transport models

Numerical solution of linear models in economics: The SP-DG model revisited

In general, complex and large dimensional models are needed to solve real economic problems. Due to these characteristics, there is either no analytical solution for them or they are not attainable. As a result, solutions can be only obtained through numerical methods. Thus, the growing importance of computers in Economics is not surprising. This paper focuses on an implementation of the SP-DG model, using Matlab,developed by the students as part of the Computational Economics course. We also discuss some of our teaching/learning experience within the course, given for the first time in the FEP Doctoral Programme in Economics.SP-DG Model, Output, Inflation, Numerical Simulation, Teaching of Economics

Temperature Fluctuations and Abundances in HII Galaxies

There is evidence for temperature fluctuations in Planetary Nebulae and in Galactic HII regions. If such fluctuations occur in the low-metallicity, extragalactic HII regions used to probe the primordial helium abundance, the derived 4He mass fraction, Y_P, could be systematically different from the true primordial value. For cooler, mainly high-metallicity HII regions the derived helium abundance may be nearly unchanged but the oxygen abundance could have been seriously underestimated. For hotter, mainly low-metallicity HII regions the oxygen abundance is likely accurate but the helium abundance could be underestimated. The net effect is to tilt the Y vs. Z relation, making it flatter and resulting in a higher inferred Y_P. Although this effect could be large, there are no data which allow us to estimate the size of the temperature fluctuations for the extragalactic HII regions. Therefore, we have explored this effect via Monte Carlos in which the abundances derived from a fiducial data set are modified by \Delta-T chosen from a distribution with 0 < \Delta-T < \Delta-T_max where \Delta-T_max is varied from 500K to 4000K. It is interesting that although this effect shifts the locations of the HII regions in Y vs. O/H plane, it does not introduce any significant additional dispersion.Comment: 11 pages, 9 postscript figures; submitted to the Ap

Determinación quelatométrica de secantes en medio no acuoso

Se presenta una modificación de la técnica complejométrica utilizada para la determinación de secantes en forma directa en un medio no acuoso. Se emplea una mezcla de benceno-isopropanol-metil glicol en la relación 1/60/50. Se titula por retorno, usando soluciones de EDTA y cloruro de cinc, empleando negro de Eriocromo T como indicador y una solución reguladora de cloruro de amonio y amoníaco. El método es aplicado a la determinación de hierro, cobre, cobalto, cinc, manganeso, plomo, bario y calcio.A modification of the technique used for the complexometric determination of driers, for being used in non aqueous solutions is presented. The solvent used is a mixture of 1 part of bencene, 60 parts of isopropanol and 30 parts of methyl glicol.The back titration performed using EDTA solution, zinc chloride solution, Eriochrome black T as indicator, and a buffer solution of amonium hidroxide and amonium chloride. This method may be applied to the determination of iron, copper, cobalt, zinc, manganese, lead, barium and calcium

FUNDAMENTOS DA LÓGICA OBJETIVA: SOBRE A RELAÇÃO ENTRE LÓGICA, ONTOLOGIA E SOCIABILIDADE BURGUESA NA LEITURA DE FILOSOFIA DO DIREITO E ENCICLOPÉDIA DAS CIÊNCIAS FILOSÓFICAS DE GEORG WILHELM FRIEDRICH HEGEL

A discussão entre analíticos e dialéticos impõe sua marca na delimitação do estatuto ontológico das estruturas normativas sociais. Compreendidas segundo a posição dada ao princípio de não-contradição, estas perspectivas orientam a razão reflexiva que figura descrições cuja forma normativa se mantém extrínseca à realidade, bem como a razão epistêmica que pressupõe a exegese sintático-formal aos desdobramentos ontológicos categoriais da realidade, desta, diga-se, uma normatividade intrínseca ao ente real. Na obra de Hegel, o condicionamento universal do sujeito particular percebe sua realização material segundo possibilidades subjetivas, condição da mediação econômica que configura a sociabilidade burguesa. Igualmente, denota o sistema de trocas como a estrutura de realização das necessidades individuais cuja permanência afirma a formalidade das relações, por isso, universais. Como desdobramento ontológico do conceito, a sociabilidade burguesa hegeliana reescreve o tratamento dialético ao princípio de não-contradição para, assim, se distinguir do discurso analítico como detentora do quesito de realização subjetiva da meritocracia liberal

Obesity and COVID-19 in-hospital fatality in southern Brazil: impact by age and skin color

OBJECTIVES: To estimate the relative risk (RR) of death associated with obesity, the attributable fraction in the exposed/with obesity (AFo), and the hospitalized population attributable risk (hospitalized PAR) associated with obesity of death among all adults and among Black and non-Black adults hospitalized for severe COVID-19 in the state of Rio Grande do Sul, Brazil. METHODS: This retrospective cohort study of prognostic factors analyzed all cases of adults hospitalized for severe COVID-19 in the state of Rio Grande do Sul, Brazil. The occurrence of obesity by hospital teams was primarily measured observing individuals’ medical records. The outcome assessed was hospital deaths caused by severe COVID-19. Poisson regression was used to estimate RRs and 95% confidence intervals (95%CI). RESULTS: The study sample consisted of 100,099 patients hospitalized for severe COVID-19, most of whom were White (84.7%) and male (54.7%). The effect of obesity was strongly modified by age. For the 18–39-year-old age group, RR = 2.54 (95%CI: 2.33–2.77), and in individuals 70 years and above, RR = 1.09 (95%CI: 1.05–1.13). For the 18–39-year-old age range, AFo = 60.6% and AFo = 42.5% in individuals 40–59 years old. For all hospitalizations, the hospitalized population attributable risk (hospitalized PAR) measuring obesity for individuals 18–39 years old was 25.3%, while in the 40–59-year-old range, the hospitalized PAR = 11.2%. The hospitalized PAR was 31.7% in the Black population aged 18–39 years and 24.8% in non-Blacks. The hospitalized PAR was also larger in Blacks aged 40-59 years. CONCLUSIONS: Obesity largely impacted in-hospital case-fatality rates among young adults and Black people contaminated by COVID-19. These data highlight the extent of the risk concerning obesity, a highly prevalent chronic condition

The Evolution of Helium and Hydrogen Ionization Corrections as HII Regions Age

Helium and hydrogen recombination lines observed in low-metallicity, extragalactic, HII regions provide the data used to infer the primordial helium mass fraction, Y_P. In deriving abundances from observations, the correction for unseen neutral helium or hydrogen is usually assumed to be absent; i.e., the ionization correction factor is taken to be unity (icf = 1). In a previous paper (VGS), we revisited the question of the icf, confirming a "reverse" ionization correction: icf < 1. In VGS the icf was calculated using more nearly realistic models of inhomogeneous HII regions, suggesting that the published values of Y_P needed to be reduced by an amount of order 0.003. As star clusters age, their stellar spectra evolve and so, too, will their icfs. Here the evolution of the icf is studied, along with that of two, alternate, measures of the "hardness" of the radiation spectrum. The differences between the icf for radiation-bounded and matter-bounded models are also explored, along with the effect on the icf of the He/H ratio (since He and H compete for some of the same ionizing photons). Particular attention is paid to the amount of doubly-ionized helium predicted, leading us to suggest that observations of, or bounds to, He++ may help to discriminate among models of HII regions ionized by starbursts of different ages and spectra. We apply our analysis to the Izotov & Thuan (IT) data set utilizing the radiation softness parameter, the [OIII]/[OI] ratio, and the presence or absence of He++ to find 0.95 < icf < 0.99. This suggests that the IT estimate of the primordial helium abundance should be reduced by Delta-Y = 0.006 +- 0.002, from 0.244 +- 0.002 to 0.238 +- 0.003.Comment: 27 double-spaced pages, 11 figures, 5 equations; revised to match the version accepted for publication in the Ap

Ionization Corrections For Low-Metallicity H II Regions and the Primordial Helium Abundance

Helium and hydrogen recombination lines observed in low-metallicity, extragalactic H II regions provide the data used to infer the primordial helium mass fraction, Y_P. The ionization corrections for unseen neutral helium (or hydrogen) are usually assumed to be absent; i.e., the ionization correction factor is taken to be unity (icf = 1). In this paper we revisit the question of the icf for H II regions ionized by clusters of young, hot, metal-poor stars. Our key result is that for the H II regions used in the determination of Y_P, there is a ``reverse'' ionization correction: icf < 1. We explore the effect on the icf of more realistic inhomogeneous H II region models and find that for those regions ionized by young stars, with ``hard'' radiation spectra, the icf is reduced further below unity. In Monte Carlos using H II region data from the literature (Izotov and Thuan 1998) we estimate a reduction in the published value of Y_P of order 0.003, which is roughly twice as large as the quoted statistical error in the Y_P determination.Comment: 23 pages, 2 postscript figures; ApJ accepted; minor change

The architecture of the 10-23 DNAzyme and its implications for DNA-mediated catalysis

Funding Information: The authors acknowledge access to the Jülich‐Düsseldorf Biomolecular NMR Center. HG is grateful for computational support and infrastructure provided by the ‘Zentrum für Informations‐ und Medientechnologie’ (ZIM) at the Heinrich Heine University Düsseldorf and the John von Neumann Institute for Computing (NIC) (user ID: HKF7, VSK33). We thank Hannah Rosenbach for providing activity data. This work was supported by the German Research Foundation (DFG) (103/4‐1, ET 103/4‐3, and the Heisenberg grant ET 103/5‐1) to ME, the Volkswagen Foundation to ME and HG (project no. 9B798) and the European Union‘s Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement no. 660258 to AV. Open Access funding enabled and organized by Projekt DEAL. Publisher Copyright: © 2022 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.Understanding the molecular features of catalytically active DNA sequences, so-called DNAzymes, is essential not only for our understanding of the fundamental properties of catalytic nucleic acids in general, but may well be the key to unravelling their full potential via tailored modifications. Our recent findings contributed to the endeavour to assemble a mechanistic picture of DNA-mediated catalysis by providing high-resolution structural insights into the 10-23 DNAzyme (Dz) and exposing a complex interplay between the Dz's unique molecular architecture, conformational plasticity, and dynamic modulation by metal ions as central elements of the DNA catalyst. Here, we discuss key features of our findings and compare them to other studies on similar systems.publishersversionpublishe