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

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

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

The UCSD HIRES/KeckI Damped Lya Abundance Database: II. The Implications

We present a comprehensive analysis of the damped Lya abundance database presented in the first paper of this series. This database provides a homogeneous set of abundance measurements for many elements including Si, Cr, Ni, Zn, Fe, Al, S, Co, O, and Ar from 38 damped Lya systems with z > 1.5. With little exception, these damped Llya systems exhibit very similar relative abundances. There is no significant correlation in X/Fe with [Fe/H] metallicity and the dispersion in X/Fe is small at all metallicity. We search the database for trends indicative of dust depletion and in a few cases find strong evidence. Specifically, we identify a correlation between [Si/Ti] and [Zn/Fe] which is unambiguous evidence for depletion. We present a discussion on the nucleosynthetic history of the damped Lya systems by focusing on abundance patterns which are minimally affected by dust depletion. We find [Si/Fe] -> +0.25 dex as [Zn/Fe] -> 0 and that the [Si/Fe] values exhibit a plateau of ~+0.3 dex at [Si/H] < -1.5 dex. Together these trends indicate significant alpha-enrichment in the damped Lya systems at low metallicity, an interpretation further supported by the observed O/Fe, S/Fe and Ar/Fe ratios. We also discuss Fe-peak nucleosynthesis and the odd-even effect. To assess the impact of dust obscuration, we present estimates of the dust-to-gas ratios for the damped Lya sightlines and crudely calculate dust extinction corrections. The distribution of extinction corrections suggests the effects of dust obscuration are minimal and that the population of 'missing' damped systems has physical characteristics similar to the observed sample. We update our investigation on the chemical evolution of the early universe in neutral gas. [significantly abridged]Comment: 29 pages, 26 figures. Uses emulateapj.sty. Accepted to ApJ: Oct 15, 200

An Imaging and Spectroscopic Study of the z=3.38639 Damped Lyman Alpha System in Q0201+1120: Clues to Star Formation Rate at High Redshift

We present the results of a series of imaging and spectroscopic observations aimed at identifying and studying the galaxy responsible for the z = 3.38639 damped lya system in the z = 3.61 QSO Q0201+1120. We find that the DLA is part of a concentration of matter which includes at least four galaxies (probably many more) over linear comoving dimensions, greater than 5h^-1Mpc. The absorber may be a 0.7 L* galaxy at an impact parameter of 15 h^-1 kpc, but follow-up spectroscopy is still required for positive identification. The gas is turbulent, with many absorption components distributed over approximately 270 km/s and a large spin temperature, T_s greater than 4000K. The metallicity is relatively high for this redshift, Z(DLA) approximately 1/20 Z(solar). From consideration of the relative ratios of elements which have different nucleosynthetic timescales, it would appear that the last major episode of star formation in this DLA occurred at z greater than 4.3, more than approximately 500 Myr prior to the time when we observe it.Comment: Accepted for publication in Ap

Infrared FeII Emission in Narrow-Line Seyfert 1 Galaxies

We obtained 0.8-2.4 micron spectra at a resolution of 320 km/s of four narrow-line Seyfert 1 galaxies in order to study the near-infrared properties of these objects. We focus on the analysis of the FeII emission in that region and the kinematics of the low-ionization broad lines. We found that the 1 micron FeII lines (9997 A, 10501 A, 10863 A and 11126 A) are the strongest FeII lines in the observed interval. For the first time, primary cascade lines of FeII arising from the decay of upper levels pumped by Ly-alpha fluorescence are resolved and identified in active galactic nuclei. Excitation mechanisms leading to the emission of the 1 micron FeII features are discussed. A combination of Ly-alpha fluorescence and collisional excitation are found to be the main contributors. The flux ratio between near-IR FeII lines varies from object to object, in contrast to what is observed in the optical region. A good correlation between the 1 micron and optical FeII emission is found. This suggests that the upper z4Fo and z4Do levels from which the bulk of the optical lines descend are mainly populated by the transitions leading to the 1 micron lines. The width and profile shape of FeII 11127, CaII 8642 and OI 8446 are very similar but significantly narrower than Pa-beta, giving strong observational support to the hypothesis that the region where FeII, CaII and OI are produced are co-spatial, interrelated kinematically and most probably located in the outermost portion of the BLR.Comment: Accepted for publication in ApJ - 35 page

Informal Caregivers’ Health Literacy in Lisbon, Portugal: A Profile for Health Promotion Prioritization

Health literacy (HL) allows people to access, understand and evaluate health information. Informal caregivers' levels of HL may impact long-term care outcomes. 'Informal caregivers' profile in Lisbon county: a health community approach' is a nurse-led research project aiming to assess informal caregivers' health literacy and associated factors in Lisbon county, as well as to foster the development of a local-specific health literacy strategy. A survey to identify a health/social caregiver profile, including questions about HL (HLS-EU-PT), was submitted to a representative sample of carers. Descriptive and bivariate inferential analysis was developed. Informal caregivers' level of HL was mostly sufficient (n = 99, 38%). More than 60% of caregivers have limited HL regarding health promotion. 'Access', 'Appraisal' and 'Use' are the information processing stages with lower mean scores of HL. Carers with low HL levels appear to be older and to have less education, low knowledge of community resources and decreased wellbeing (p < 0.05). A strategy focused on health promotion-related HL through primary care resources can potentially improve caregivers' knowledge, competencies and motivation, as well as health system sustainability. Reported HLS-EU-PT scores deserve special attention. Future work should emphasize the role of HL-associated factors and health outcomes for caregivers and cared-for persons.info:eu-repo/semantics/publishedVersio

Does Reality Overcome the Expected? Survey on Informal Caregivers' Profile: A Nurse-Led Study in Times of COVID-19

The increasing overload of chronic conditions raises challenges for the health system. Informal caregivers have a major role in ensuring the quality of life of the cared-for person, despite the reported lack of working resources which can lead to unmet needs. This article reports on the first part of a nurse-led research project entitled “Informal caregiver’ profiles in Lisbon county: a health community approach.’ We aimed to support decision-making by developing an informal caregiver profile to promote tailored interventions. A survey addressing the dyad was developed and submitted to a convenient, network-based, stratified sample of carers aged 18 years or above. More than thirty community partners supported the identification of caregivers. Data were submitted to univariate descriptive analysis. A profile of the cared-for person and the informal caregiver was uncovered by identifying 639 caregivers, of whom the majority lived with the cared-for person. Only four percent planned the transition to a caregiver role, and no more than 10% had access to support programs. Approximately half of the respondents found that COVID-19 negatively impacted their performance in the caregiver role. Developing a local and tailored strategy with collaboration between healthcare professionals, academics, and community partners is key to ensuring that meaningful support is provided to caregivers.info:eu-repo/semantics/publishedVersio

BBN and the Primordial Abundances

The relic abundances of the light elements synthesized during the first few minutes of the evolution of the Universe provide unique probes of cosmology and the building blocks for stellar and galactic chemical evolution, while also enabling constraints on the baryon (nucleon) density and on models of particle physics beyond the standard model. Recent WMAP analyses of the CBR temperature fluctuation spectrum, combined with other, relevant, observational data, has yielded very tight constraints on the baryon density, permitting a detailed, quantitative confrontation of the predictions of Big Bang Nucleosynthesis with the post-BBN abundances inferred from observational data. The current status of this comparison is presented, with an emphasis on the challenges to astronomy, astrophysics, particle physics, and cosmology it identifies.Comment: To appear in the Proceedings of the ESO/Arcetri Workshop on "Chemical Abundances and Mixing in Stars in the Milky Way and its Satellites", eds., L. Pasquini and S. Randich (Springer-Verlag Series, "ESO Astrophysics Symposia"