862 research outputs found
Burrowing apparatus
A soil burrowing mole is described in which a housing has an auger blade wound around a front portion. This portion is rotatable about a housing longitudinal axis relative to an externally finned housing rear portion upon operation of driving means to cause an advance through soil and the like. The housing carries a sensor sensitive to deviation from a predetermined path and to which is coupled means for steering the housing to maintain the path
Linearized dynamical model for the NASA/IEEE SCOLE configuration
The linearized equation of motion for the NASA/IEEE SCOLE configuration are developed. The derivation is based on the method of Lagrange and the equations are assembled into matrix second order form
Cold-air investigation of a 4 1/2 stage turbine with stage-loading factor of 4.66 and high specific work output. 2: Stage group performance
The stage group performance of a 4 1/2 stage turbine with an average stage loading factor of 4.66 and high specific work output was determined in cold air at design equivalent speed. The four stage turbine configuration produced design equivalent work output with an efficiency of 0.856; a barely discernible difference from the 0.855 obtained for the complete 4 1/2 stage turbine in a previous investigation. The turbine was designed and the procedure embodied the following design features: (1) controlled vortex flow, (2) tailored radial work distribution, and (3) control of the location of the boundary-layer transition point on the airfoil suction surface. The efficiency forecast for the 4 1/2 stage turbine was 0.886, and the value predicted using a reference method was 0.862. The stage group performance results were used to determine the individual stage efficiencies for the condition at which design 4 1/2 stage work output was obtained. The efficiencies of stages one and four were about 0.020 lower than the predicted value, that of stage two was 0.014 lower, and that of stage three was about equal to the predicted value. Thus all the stages operated reasonably close to their expected performance levels, and the overall (4 1/2 stage) performance was not degraded by any particularly inefficient component
Cold air investigation of 4 1/2-stage turbine with stage loading factor of 4.66 and high specific work output. 1: Overall performance
The turbine developed design specific work output at design speed at a total pressure ratio of 6.745 with a corresponding efficiency of 0.855. The efficiency (0.855)was 3.1 points lower than the estimated efficiency quoted by the contractor in the design report and 0.7 of a point lower than that determined by a reference prediction method. The performance of the turbine, which was a forced vortex design, agreed with the performance determined by the prediction method to about the same extent as did the performance of three reference high stage loading factor turbines, which were free vortex designs
Spatial Distance Between Parents and Adult Children in the United States
ObjectiveThis brief report presents contemporary national estimates of the spatial distance between residences of parents and adult children in the United States, including distance to one’s nearest parent or adult child and whether one lives near all of their parents and adult children.BackgroundThe most recent national estimates of parent–child spatial proximity come from data for the early 1990s. Moreover, research has rarely assessed the spatial clustering of all parents and adult children.MethodData are from the 2013 Panel Study of Income Dynamics on residential locations of adults aged 25 years and older and each of their parents and adult children. The following two measures of spatial proximity were estimated: the share of adults who have their nearest parent or adult child at a given distance and the share of adults who have all parents and/or all adult children at a given distance. Sociodemographic and geographic differences were examined for both measures.ResultsAmong the adults with at least one living parent or adult child, a significant majority (74.8%) had their nearest parent or adult child within 30 miles, and about one third (35.5%) had all parents and adult children living that close. Spatial proximity differed substantially among sociodemographic groups, with those who were disadvantaged more likely to have their parents or adult children nearby. In most cases, sociodemographic disparities were much higher when spatial proximity was measured by proximity to all parents and all adult children instead of to the nearest parent or nearest adult child.ConclusionDisparities in having all parents and/or adult children nearby may be a result of family solidarity and also may affect family solidarity. This report sets the stage for new investigations of the spatial dimension of family cohesion.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154398/1/jomf12606_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154398/2/jomf12606.pd
Constraints and opportunities for implementing nutrition-specific, agricultural and market-based approaches to improve nutrient intake adequacy among infants and young children in two regions of rural Kenya.
Several types of interventions can be used to improve nutrient intake adequacy in infant and young child (IYC) diets, including fortified foods, home fortification, nutrition education and behaviour change communication (BCC) in addition to agricultural and market-based strategies. However, the appropriate selection of interventions depends on the social, cultural, physical and economic context of the population. Derived from two rural Kenyan populations, this analysis combined information from: (1) a quantitative analysis to derive a set of food-based recommendations (FBRs) to fill nutrient intake gaps in IYC diets and identify 'problem nutrients' for which intake gaps require solutions beyond currently available foods and dietary patterns, and (2) an ethnographic qualitative analysis to identify contextual factors posing opportunities or constraints to implementing the FBRs, including perceptions of cost, convenience, accessibility and appropriateness of the recommended foods for IYC diets and other social or physical factors that determine accessibility of those foods. Opportunities identified included BCC to increase the acceptability and utilisation of green leafy vegetables (GLV) and small fish and agronomic interventions to increase the productivity of GLV and millet. Value chains for millet, beans, GLV, milk and small fish should be studied for opportunities to increase their accessibility in local markets. Processor-level interventions, such as partially cooked fortified dry porridge mixes or unfortified cereal mixes incorporating millet and beans, may increase the accessibility of foods that provide increased amounts of the problem nutrients. Multi-sectoral actors and community stakeholders should be engaged to assess the feasibility of implementing these locally appropriate strategies
Surfactant protein-D and exposure to bioaerosols in wastewater and garbage workers
Purpose: Bioaerosols and their constituents, such as endotoxins, are capable of causing an inflammatory reaction at the level of the lung-blood barrier, which becomes more permeable. Thus, it was hypothesized that occupational exposure to bioaerosols can increase leakage of surfactant protein-D (SP-D), a lung-specific protein, into the bloodstream. Methods: SP-D was determined by ELISA in 316 wastewater workers, 67 garbage collectors, and 395 control subjects. Exposure was assessed with four interview-based indicators and by preliminary endotoxin measurements using the Limulus amoebocyte lysate assay. Influence of exposure on serum SP-D was assessed by multiple linear regression considering smoking, glomerular function, lung diseases, obesity, and other confounders. Results: Overall, mean exposure levels to endotoxins were below 100EU/m3. However, special tasks of wastewater workers caused higher endotoxin exposure. SP-D concentration was slightly increased in this occupational group and associated with the occurrence of splashes and contact to raw sewage. No effect was found in garbage collectors. Smoking increased serum SP-D. No clinically relevant correlation between spirometry results and SP-D concentrations appeared. Conclusions: These results support the hypothesis that inhalation of bioaerosols, even at low concentrations, has a subclinical effect on the lung-blood barrier, the permeability of which increases without associated spirometric change
Volumetric optoacoustic neurobehavioral tracking of epileptic seizures in freely-swimming zebrafish larvae
Fast three-dimensional imaging of freely-swimming zebrafish is essential to understand the link between neuronal activity and behavioral changes during epileptic seizures. Studying the complex spatiotemporal patterns of neuronal activity at the whole-brain or -body level typically requires physical restraint, thus hindering the observation of unperturbed behavior. Here we report on real-time volumetric optoacoustic imaging of aberrant circular swimming activity and calcium transients in freely behaving zebrafish larvae, continuously covering their motion across an entire three-dimensional region. The high spatiotemporal resolution of the technique enables capturing ictal-like epileptic seizure events and quantifying their propagation speed, independently validated with simultaneous widefield fluorescence recordings. The work sets the stage for discerning functional interconnections between zebrafish behavior and neuronal activity for studying fundamental mechanisms of epilepsy and in vivo validation of treatment strategies
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