6,788 research outputs found
Morphometric Study of Two Drainage Basins Near Iowa City, Iowa
A morphometric study was made of the adjoining drainage basins of east-flowing Old Man Creek and Clear Creek in Johnson and Iowa counties, Iowa. In terms of the parameters measured, these basins are essentially similar. They agree with laws for drainage basins proposed by Horton and are therefore normal rather than misfit . Part of the Clear Creek basin was invaded by Iowan ice and this probably accounts for some abnormal data. Distinct longitudinal asymmetry and obviously steeper south valley walls are probably best explained by the differences in loess thickness on valley sides
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Multiphase measurement of blood flow in a microchannel
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Blood is a complex fluid comprising red blood cells (RBCs) suspended in a continuous medium. Recent studies have shown that the spatial concentration distributions of the RBCs have a considerable impact on their velocity distributions. By extending this analysis, we present the first multiphase experimental analysis of microscale blood flow to include local velocity and concentration distributions of both phases of the blood. Human blood is perfused though a PDMS microchannel comprising a sequentially bifurcating geometry with a 50×50μm cross-section. The flow rate and the proportion of flow entering the branches of the bifurcation are varied, and the effects on the velocity and concentration distributions of the RBCs and suspending medium are analysed. In addition, the influence of RBC aggregation is investigated. The relative velocity between the two phases of the blood is shown to be dependent to varying degrees on all of the independent parameters examined in this study. A mechanism for the observed trends based on collisions of RBCs with the channel walls in the bifurcation is proposed
Study of aircraft in intraurban transportation systems, volume 1
An analysis of an effective short range, high density computer transportation system for intraurban systems is presented. The seven county Detroit, Michigan, metropolitan area, was chosen as the scenario for the analysis. The study consisted of an analysis and forecast of the Detroit market through 1985, a parametric analysis of appropriate short haul aircraft concepts and associated ground systems, and a preliminary overall economic analysis of a simplified total system designed to evaluate the candidate vehicles and select the most promising VTOL and STOL aircraft. Data are also included on the impact of advanced technology on the system, the sensitivity of mission performance to changes in aircraft characteristics and system operations, and identification of key problem areas that may be improved by additional research. The approach, logic, and computer models used are adaptable to other intraurban or interurban areas
Decay of the Z Boson into Scalar Particles
In extensions of the standard model, light scalar particles are often
possible because of symmetry considerations. We study the decay of the Z boson
into such particles. In particular, we consider for illustration the scalar
sector of a recently proposed model of the 17-keV neutrino which satisfies all
laboratory, astrophysical, and cosmological constraints.Comment: 11 pages (2 figures, not included) (Revised, Oct 1992). Some
equations have been corrected and 1 figure has been eliminate
Longitudinal patterns in an Arkansas River Valley stream: an Application of the River Continuum Concept
The River Continuum Concept (RCC) provides the framework for studying how lotic ecosystems vary from headwater streams to large rivers. The RCC was developed in streams in eastern deciduous forests of North America, but watershed characteristics and land uses differ across ecoregions, presenting unique opportunities to study how predictions of the RCC may differ across regions. Additionally, RCC predictions may vary due to the influence of fishes, but few studies have used fish taxa as a metric for evaluating predictions of the RCC. Our goal was to determine if RCC predictions for stream orders 1 through 5 were supported by primary producer, macroinvertebrate, and fish communities in Cadron Creek of the Arkansas River Valley. We sampled chlorophyll a, macroinvertebrates, and fishes at five stream reaches across a gradient of watershed size. Contrary to RCC predictions, chlorophyll a did not increase in concentration with catchment size. As the RCC predicts, fish and macroinvertebrate diversity increased with catchment size. Shredding and collecting macroinvertebrate taxa supported RCC predictions, respectively decreasing and increasing in composition as catchment area increased. Herbivorous and predaceous fish did not follow RCC predictions; however, surface-water column feeding fish were abundant at all sites as predicted. We hypothesize some predictions of the RCC were not supported in headwater reaches of this system due to regional differences in watershed characteristics and altered resource availability due to land use surrounding sampling sites
Weight loss, glycemic control, and cardiovascular disease risk factors in response to differential diet composition in a weight loss program in type 2 diabetes: a randomized controlled trial.
ObjectiveTo test whether a weight loss program promotes greater weight loss, glycemic control, and improved cardiovascular disease risk factors compared with control conditions and whether there is a differential response to higher versus lower carbohydrate intake.Research design and methodsThis randomized controlled trial at two university medical centers enrolled 227 overweight or obese adults with type 2 diabetes and assigned them to parallel in-person diet and exercise counseling, with prepackaged foods in a planned menu during the initial phase, or to usual care (UC; two weight loss counseling sessions and monthly contacts).ResultsRelative weight loss was 7.4% (95% CI 5.7-9.2%), 9.0% (7.1-10.9%), and 2.5% (1.3-3.8%) for the lower fat, lower carbohydrate, and UC groups (P < 0.001 intervention effect). Glycemic control markers and triglyceride levels were lower in the intervention groups compared with UC group at 1 year (fasting glucose 141 [95% CI 133-149] vs. 159 [144-174] mg/dL, P = 0.023; hemoglobin A1c 6.9% [6.6-7.1%] vs. 7.5% [7.1-7.9%] or 52 [49-54] vs. 58 [54-63] mmol/mol, P = 0.001; triglycerides 148 [134-163] vs. 204 [173-234] mg/dL, P < 0.001). The lower versus higher carbohydrate groups maintained lower hemoglobin A1c (6.6% [95% CI 6.3-6.8%] vs. 7.2% [6.8-7.5%] or 49 [45-51] vs. 55 [51-58] mmol/mol) at 1 year (P = 0.008).ConclusionsThe weight loss program resulted in greater weight loss and improved glycemic control in type 2 diabetes
Feedlot Surface Conditions and Ammonia Emissions
Moisture and urine were applied to a feedlot surface in a 2x2 factorial design. Forced-air wind tunnels were used to determine differences in the net flux of ammonia (NH3) being volatilized. Surface DM, pH and surface temperature were all analyzed within each treatment to determine effect on NH3 net flux. No effects of urine were detected. There were differences detected due to moisture and moisture*time with the dry plots releasing significantly more NH3
Feedlot Surface Conditions and Ammonia Emissions
Moisture and urine were applied to a feedlot surface in a 2x2 factorial design. Forced-air wind tunnels were used to determine differences in the net flux of ammonia (NH3) being volatilized. Surface DM, pH and surface temperature were all analyzed within each treatment to determine effect on NH3 net flux. No effects of urine were detected. There were differences detected due to moisture and moisture*time with the dry plots releasing significantly more NH3
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Carbonyl sulfide and carbon disulfide: Large-scale distributions over the western Pacific and emissions from Asia during TRACE-P
An extensive set of carbonyl sulfide (OCS) and carbon disulfide (CS2) observations were made as part of the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) project, which took place in the early spring 2001. TRACE-P sampling focused on the western Pacific region but in total included the geographic region 110°E to 290°E longitude, 5°N to 50°N latitude, and 0–12 km altitude. Substantial OCS and CS2 enhancements were observed for a great many air masses of Chinese and Japanese origin during TRACE-P. Over the western Pacific, mean mixing ratios of long-lived OCS and shorter-lived CS2 showed a gradual decrease by about 10% and a factor of 5–10, respectively, from the surface to 8–10 km altitude, presumably because land-based sources dominated their distribution during February through April 2001. The highest mean OCS and CS2levels (580 and 20 pptv, respectively, based on 2.5° × 2.5° latitude bins) were observed below 2 km near the coast of Asia, at latitudes between 25°N and 35°N, where urban Asian outflow was strongest. Ratios of OCS versus CO for continental SE Asia were much lower compared to Chinese and Japanese signatures and were strongly associated with biomass burning/biofuel emissions. We present a new inventory of anthropogenic Asian emissions (including biomass burning) for OCS and CS2 and compare it to emission estimates based on regional relationships of OCS and CS2 to CO and CO2. The OCS and CS2 results for the two methods compare well for continental SE Asia and Japan plus Korea and also for Chinese CS2 emissions. However, it appears that the inventory underestimates Chinese emissions of OCS by about 30–100%. This difference may be related to the fact that we did not include natural sources such as wetland emissions in our inventory, although the contributions from such sources are believed to be at a seasonal low during the study period. Uncertainties in OCS emissions from Chinese coal burning, which are poorly characterized, likely contribute to the discrepancy
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Atmospheric sampling of Supertyphoon Mireille with NASA DC-8 aircraft on September 27,1991, during PEM-West A
The DC-8 mission of September 27, 1991, was designed to sample air flowing into Typhoon Mireille in the boundary layer, air in the upper tropospheric eye region, and air emerging from the typhoon and ahead of the system, also in the upper troposphere. The objective was to find how a typhoon redistributes trace constituents in the West Pacific region and whether any such redistribution is important on the global scale. The boundary layer air (300 m), in a region to the SE of the eye, contained low mixing ratios of the tracer species O3, CO, C2H6, C2H2, C3H8, C6H6and CS2 but high values of dimethylsulfide (DMS). The eye region relative to the boundary layer, showed somewhat elevated levels of CO, substantially increased levels of O3, CS2 and all nonmethane hydrocarbons (NMHCs), and somewhat reduced levels of DMS. Ahead of the eye, CO and the NMHCs remained unchanged, O3 and CS2 showed a modest decrease, and DMS showed a substantial decrease. There was no evidence from lidar cross sections of ozone for the downward entrainment of stratospheric air into the eye region; these sections show that low ozone values were measured in the troposphere. The DMS data suggest substantial entrainment of boundary layer air into the system, particularly into the eye wall region. Estimates of the DMS sulphur flux between the boundary layer and the free troposphere, based on computations of velocity potential and divergent winds, gave values of about 69 μg S m−2 d−1 averaged over a 17.5° grid square encompassing the typhoon. A few hours after sampling with the DC-8, Mireille passed over Oki Island, just to the north of Japan, producing surface values of ozone of 5.5 ppbv. These O3 levels are consistent with the low tropospheric values found by lidar and are more typical of equatorial regions. We suggest that the central eye region may act like a Taylor column which has moved poleward from low latitudes. The high-altitude photochemical environment within Typhoon Mireille was found to be quite active as evidenced by significant levels of measured gas phase H2O2 and CH3OOH and model-computed levels of OH
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