1,282 research outputs found
Hot filament technique for measuring the thermal conductivity of molten lithium fluoride
Molten salts, such as lithium fluoride, are attractive candidates for thermal energy storage in solar dynamic space power systems because of their high latent heat of fusion. However, these same salts have poor thermal conductivities which inhibit the transfer of heat into the solid phase and out of the liquid phase. One concept for improving the thermal conductivity of the thermal energy storage system is to add a conductive filler material to the molten salt. High thermal conductivity pitch-based graphite fibers are being considered for this application. Although there is some information available on the thermal conductivity of lithium fluoride solid, there is very little information on lithium fluoride liquid, and no information on molten salt graphite fiber composites. This paper describes a hot filament technique for determining the thermal conductivity of molten salts. The hot filament technique was used to find the thermal conductivity of molten lithium fluoride at 930 C, and the thermal conductivity values ranged from 1.2 to 1.6 W/mK. These values are comparable to the slightly larger value of 5.0 W/mK for lithium fluoride solid. In addition, two molten salt graphite fiber composites were characterized with the hot filament technique and these results are also presented
A Procedure for Uncovering Acceptable and Nonacceptable Mortgage Applications through Discriminant Analysis Using Ranked Data
The procedure developed in this paper uses a less biased statistical technique than conventional discriminant analysis and parallels the ranking procedure used by loan officers. A variety of univariate and multivariate statistical procedures as well as comprehensive validation methods are used to develop a "best" model. The resulting model provides more accurate classification than other studies have shown, without violating federal law regarding discrimination.
Loop Current Spin-off Eddies, Slope Currents and Dispersal of Reef Fish Larvae from The Flower Gardens National Marine Sanctuary and The Florida Middle Grounds
Large energetic spin—off eddies from Loop Current intrusions into the Gulf of Mexico play a major role in water exchange between the continental shelf and the deep basin in the northern Gulf. Reef fish larvae, spawned on the outer shelf and planktonic during their early life history, are broadly dispersed by this mechanism, but may be lost to the cohort by transport away from suitable settlement habitat. In this study, satellite altimeter data—assimilative ocean model currents (HYCOM) from 2003—2015 are used to calculate kinetic energy of the mixed layer over the upper continental slope (200 m —1000 m) due to eddy interactions with the shelf and to track the dispersal of larvae spawned during core summer (June—August) season. Over the 13 year model period, dispersal into the deep basin from the Flower Gardens National Marine Sanctuary averaged 63.5%, with a high of 90.8% and a low of 34.6%. Dispersal from the Florida Middle Grounds averaged 9.5%, with a high of 23.1% and a low of 0.6%. Temporal dispersal of larvae was associated with trends in turbulent kinetic energy and mean kinetic energy over the continental slope, and varied with the North Atlantic Oscillation Index. Between 2010 and 2011, mean kinetic energy replaced turbulent kinetic energy as the dominant dispersal mechanism
Evaluation of Extent and Bioavailability of Chromium Contamination Near an Abandoned Strip Mine
Chromium is a potentially toxic element to plants and animals commonly associated with serpentine and anthropogenic sources. An abandoned Cr strip-mine at US National Guard Camp SLO, CA containing serpentinitic parent material was tested for total and bioavailable Cr in the soil and overlying vegetation via US EPA Methods 3050a (Total Cr) and 1311 (Total Characteristic Leaching Procedure, TCLP) (US EPA, 1995), respectively. The analysis of total and bioavailable Cr was used to assess the risk of nearby surface and groundwater contamination and to evaluate the site’s need for remediation. In addition, trends in soil Cr levels with respect to slope position and sampling transect were identified. Total and most bioavailable Cr concentrations in plants were below the method detection limits (TotalMDL = 0.12 mg L-1; TCLPMDL = 0.04 mg L-1), suggesting the Cr was immobile and not bioavailable. The average total Cr level was 403.5 +/- 177.6 mg kg-1, significantly below the background total Cr level of 829.4 +/- 213.6 mg kg-1. Based on Chromium’s immobility, and its low levels in the site relative to background concentrations, remediation practices were not recommended. No significant trends were observed in total soil Cr levels along any transect or between sampled slope positions. The information gained from this was used by Camp SLO officers to assess the threat of Cr mobility and bioavailability in the soils at this site, as well as in nearby waterways and ground water
Pre- and Post Impoundment Ichthyoparasite Succession in a New Arkansas Reservoir
Helminth and crustacean parasites from 2,387 Micropterus dolomieui, M. punctulatus, and M. salmoides were utilized to monitor annual pre- and postimpoundment succession patterns spanning eight con- tinuous years in Beaver Reservoir, Arkansas. Incidence of infection by ichthyoparasites with direct life cycles (monogenetic trematodes, leeches, and crustaceans) generally increased following impoundment, although leeches remained relatively constant. Exceptions to this general pattern occurred. Incidence of ichthyoparasites with indirect life cycles (digenetic trematodes, cestodes, acanthocephalans, and nematodes) decreased immediately following impoundment with subsequent increases to a point equal or above that of preimpoundment, although exceptions occurred. Time for species adaptation to the reservoir environment varied, with some species disappearing and others occurring for the first time. Diversity indices indicated that a moderate parasite community was maintained in the White River two years prior to its impoundment to form Beaver Reservoir. During the first impoundment year the parasite community declined to the lowest postimpoundment level with the abrupt change in habitat. Throughout the following four post- impoundment years the parasite community gradually increased to become much larger and more complex than it was during preimpoundment. Parasite community succession stabilization occurred in the fifth postimpoundment year and continued the following year indicating the establishment of a climax ichthyoparasite community
Prenatal transportation stress did not impact ovarian follicle count for three generations of female Brahman offspring
As prenatal transportation stress altered behavior and adrenal glucocorticoid secretion of calves, we hypothesized that prenatal transportation stress would decrease ovarian reserve size and negatively impact female offspring fertility. The impact of prenatal transportation stress on ovarian follicle numbers in female offspring for three generations was studied. Brahman cows were transported for 2 h on day 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 of gestation. Ovaries were collected from offspring of transported or non-transported dams at multiple ages. Primordial, primary, secondary, and antral follicles were histologically analyzed. Antral follicle numbers were determined by ultrasound in a subset of offspring. Numbers of primordial, primary, secondary, and antral follicles were analyzed using the MIXED procedure, while the CORR procedure of SAS was used to determine the correlation between follicles observed by ultrasonography and histology. There were no differences (P \u3e 0.05) in the number of primordial, primary, secondary, antral, or total follicles observed histologically due to treatment. Younger females had significantly greater numbers of follicles than older females (P \u3c 0.0001). Antral follicles tended to be correlated with total histological ovarian follicles (P = 0.10). There was no difference in the number of antral follicles observed at ultrasound due to treatment (P = 0.3147), or generation (P = 0.6005) when controlling for age at observation. These results show that short-term transportation stress during early- to mid-gestation did not impact fertility as measured by ovarian follicle numbers in female Brahman offspring for three generations
Impact of Allergic Reactions on Food-Specific IgE Concentrations and Skin Test Results
Although there is concern that food allergic reactions may negatively affect the natural history of food allergy, the impact of reactions on food-specific IgE (sIgE) or skin prick tests is unknown
Plans and Status of Wind-Tunnel Testing Employing an Aeroservoelastic Semispan Model
This paper presents the research objectives, summarizes the pre-wind-tunnel-test experimental results to date, summarizes the analytical predictions to date, and outlines the wind-tunnel-test plans for an aeroservoelastic semispan wind-tunnel model. The model is referred to as the Supersonic Semispan Transport (S4T) Active Controls Testbed (ACT) and is based on a supersonic cruise configuration. The model has three hydraulically-actuated surfaces (all-movable horizontal tail, all-movable ride control vane, and aileron) for active controls. The model is instrumented with accelerometers, unsteady pressure transducers, and strain gages and will be mounted on a 5-component sidewall balance. The model will be tested twice in the Langley Transonic Dynamics Tunnel (TDT). The first entry will be an "open-loop" model-characterization test; the second entry will be a "closed-loop" test during which active flutter suppression, gust load alleviation and ride quality control experiments will be conducted
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Reduced T2* Values in Soleus Muscle of Patients with Type 2 Diabetes Mellitus
Tissue water transverse relaxation times (T2) are highly sensitive to fluid and lipid accumulations in skeletal muscles whereas the related T2* is sensitive to changes in tissue oxygenation in addition to factors affecting T2. Diabetes mellitus (DM) affects muscles of lower extremities progressively by impairing blood flow at the macrovascular and microvascular levels. This study is to investigate whether T2 and T2* are sensitive enough to detect abnormalities in skeletal muscles of diabetic patients in the resting state. T2 and T2* values in calf muscle of 18 patients with type 2 DM (T2DM), 22 young healthy controls (YHC), and 7 age-matched older healthy controls (OHC) were measured at 3T using multi-TE spin echo and gradient echo sequences. Regional lipid levels of the soleus muscle were also measured using the Dixon method in a subset of the subjects. Correlations between T2, T2*, lipid levels, glycated hemoglobin (HbA1c) and presence of diabetes were evaluated. We found that T2 values were significantly higher in calf muscles of T2DM subjects, as were T2* values in anterior tibialis, and gastrocnemius muscles of T2DM participants. However, soleus T2* values of the T2DM subjects were significantly lower than those of the older, age-matched HC cohort . The soleus T2* values in the T2DM cohort were inversely correlated with the presence of diabetes (t = −3.46, p<0.001) and with an increase in HbA1c, but not with body mass index or regional lipid levels. Although multiple factors may contribute to changes in T2* values, the lowered T2* value observed in the T2DM soleus muscle is most consistent with a combination of high oxygen consumption and poor regional perfusion. This finding is consistent with results of previous perfusion studies and suggests that the soleus in individuals with T2DM is likely under tissue oxygenation stress
Aerosol meteorology of Maritime Continent for the 2012 7SEAS southwest monsoon intensive study - Part 2: Philippine receptor observations of fine-scale aerosol behavior
Abstract. The largest 7 Southeast Asian Studies (7SEAS) operations period within the Maritime Continent (MC) occurred in the August–September 2012 biomass burning season. Data included were observations aboard the M/Y Vasco, dispatched to the Palawan Archipelago and Sulu Sea of the Philippines for September 2012. At these locations, the Vasco observed MC smoke and pollution entering the southwest monsoon (SWM) monsoonal trough. Here we describe the research cruise findings and the finer-scale aerosol meteorology of this convectively active region. This 2012 cruise complemented a 2-week cruise in 2011 and was generally consistent with previous findings in terms of how smoke emission and transport related to monsoonal flows, tropical cyclones (TC), and the covariance between smoke transport events and the atmosphere's thermodynamic structure. Biomass burning plumes were usually mixed with significant amounts of anthropogenic pollution. Also key to aerosol behavior were squall lines and cold pools propagating across the South China Sea (SCS) and scavenging aerosol particles in their path. However, the 2012 cruise showed much higher modulation in aerosol frequency than its 2011 counterpart. Whereas in 2011 large synoptic-scale aerosol events transported high concentrations of smoke into the Philippines over days, in 2012 measured aerosol events exhibited a much shorter-term variation, sometimes only 3–12 h. Strong monsoonal flow reversals were also experienced in 2012. Nucleation events in cleaner and polluted conditions, as well as in urban plumes, were observed. Perhaps most interestingly, several cases of squall lines preceding major aerosol events were observed, as opposed to 2011 observations where these lines largely scavenged aerosol particles from the marine boundary layer. Combined, these observations indicate pockets of high and low particle counts that are not uncommon in the region. These perturbations are difficult to observe by satellite and very difficult to model. Indeed, the Navy Aerosol Analysis and Prediction System (NAAPS) simulations captured longer period aerosol events quite well but largely failed to capture the timing of high-frequency phenomena. Ultimately, the research findings of these cruises demonstrate the real world challenges of satellite-based missions, significant aerosol life cycle questions such as those the future Aerosol/Clouds/Ecosystems (ACE) will investigate, and the importance of small-scale phenomena such as sea breezes, squall lines, and nucleation events embedded within SWM patterns in dominating aerosol life cycle and potential relationships to clouds
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