Propellant Chemistry for CFD Applications

Current concepts for reusable launch vehicle design have created renewed interest in the use of RP-1 fuels for high pressure and tri-propellant propulsion systems. Such designs require the use of an analytical technology that accurately accounts for the effects of real fluid properties, combustion of large hydrocarbon fuel modules, and the possibility of soot formation. These effects are inadequately treated in current computational fluid dynamic (CFD) codes used for propulsion system analyses. The objective of this investigation is to provide an accurate analytical description of hydrocarbon combustion thermodynamics and kinetics that is sufficiently computationally efficient to be a practical design tool when used with CFD codes such as the FDNS code. A rigorous description of real fluid properties for RP-1 and its combustion products will be derived from the literature and from experiments conducted in this investigation. Upon the establishment of such a description, the fluid description will be simplified by using the minimum of empiricism necessary to maintain accurate combustion analyses and including such empirical models into an appropriate CFD code. An additional benefit of this approach is that the real fluid properties analysis simplifies the introduction of the effects of droplet sprays into the combustion model. Typical species compositions of RP-1 have been identified, surrogate fuels have been established for analyses, and combustion and sooting reaction kinetics models have been developed. Methods for predicting the necessary real fluid properties have been developed and essential experiments have been designed. Verification studies are in progress, and preliminary results from these studies will be presented. The approach has been determined to be feasible, and upon its completion the required methodology for accurate performance and heat transfer CFD analyses for high pressure, tri-propellant propulsion systems will be available

Thyroid hormones correlate with resting metabolic rate, not daily energy expenditure, in two charadriiform seabirds

K. Woo, M. Le Vaillant, T. van Nus, and especially A. Wesphal, J. Schultner and I. Dorresteijn, assisted with field work, often under unpleasant conditions. K. Wauthier was instrumental in wrestling the gamma counter into submission. P. Redman and C. Hambly conducted the isotopic analyses. K. Scott and K. Campbell provided the FoxBox. K.H.E. benefited from a Natural Sciences and Engineering Research Council (NSERC) Vanier Scholarship, Association of Canadian Universities for Northern Studies Garfield Weston Northern Studies Award and the Arctic Institute of North America Jennifer Robinson Scholarship. Research support came from Bird Studies Canada/Society of Canadian Ornithologists James Baillie Award, Animal Behavior Society Research Grant, American Ornithologists’ Union Research Grant, Frank Chapman Research Grant, the Waterbird Society Nisbet Grant and NSERC Discovery Grants to J.F.H. and W.G.A. Any use of trade names is for descriptive purposes only and does not imply endorsement by the US Government.Peer reviewedPublisher PD

Relationship between high sodium levels in municipally softened drinking water and elevated blood pressure

A recent study in Massachusetts found that a group of high school sophomores exposed to 107 mg/l sodium in their drinking water had significantly higher blood pressures than a control group exposed to a lower level of sodium (8 mg/l). The present study was undertaken in Illinois to determine if these findings could be repeated with a group of high school juniors and seniors from two communities, LaGrange and Westchester, located in the Chicago metropolitan area. The concentration of sodium in LaGrange's municipal drinking water is 405 mg/l as compared to 4 mg/l for Westchester. Of the 386 eligible students in LaGrangeI.84%volunteered to have their blood pressures taken. In Westchester, 78% of the 401 eligible students volunteered. Results of the survey indicated that male and female systolic blood pressures in the high sodium community were not higher than those in the low-sodium community (p > 0.05). In contrast, the male and female diastolic blood pressures were significantly higher in the high-sodium community (p < 0.05). However, the increases in diastolic blood pressures were not as large as those observed in the Massachusetts study. The long-term significance of these findings is unknown. However, they do indicate a need for further follow-up study to determine if there is an association with the development of hypertension.U.S. Department of the InteriorU.S. Geological SurveyOpe

Lexical organization in deaf children who use British Sign Language: Evidence from a semantic fluency task

We adapted the semantic fluency task into British Sign Language (BSL). In Study 1, we present data from twenty-two deaf signers aged four to fifteen. We show that the same ‘cognitive signatures’ that characterize this task in spoken languages are also present in deaf children, for example, the semantic clustering of responses. In Study 2, we present data from thirteen deaf children with Specific Language Impairment (SLI) in BSL, in comparison to a subset of children from Study 1 matched for age and BSL exposure. The two groups' results were comparable in most respects. However, the group with SLI made occasional word-finding errors and gave fewer responses in the first 15 seconds. We conclude that deaf children with SLI do not differ from their controls in terms of the semantic organization of the BSL lexicon, but that they access signs less efficiently

Hierarchical Bayesian Spatio-Temporal Analysis of Climatic and Socio-Economic Determinants of Rocky Mountain Spotted Fever

Citation: Raghavan, R. K., Goodin, D. G., Neises, D., Anderson, G. A., & Ganta, R. R. (2016). Hierarchical Bayesian Spatio-Temporal Analysis of Climatic and Socio-Economic Determinants of Rocky Mountain Spotted Fever. Plos One, 11(3), 17. doi:10.1371/journal.pone.0150180This study aims to examine the spatio-temporal dynamics of Rocky Mountain spotted fever (RMSF) prevalence in four contiguous states of Midwestern United States, and to determine the impact of environmental and socio-economic factors associated with this disease. Bayesian hierarchical models were used to quantify space and time only trends and spatio-temporal interaction effect in the case reports submitted to the state health departments in the region. Various socio-economic, environmental and climatic covariates screened a priori in a bivariate procedure were added to a main-effects Bayesian model in progressive steps to evaluate important drivers of RMSF space-time patterns in the region. Our results show a steady increase in RMSF incidence over the study period to newer geographic areas, and the posterior probabilities of county-specific trends indicate clustering of high risk counties in the central and southern parts of the study region. At the spatial scale of a county, the prevalence levels of RMSF is influenced by poverty status, average relative humidity, and average land surface temperature (> 35 degrees C) in the region, and the relevance of these factors in the context of climate-change impacts on tick-borne diseases are discussed