1,513 research outputs found
Astronaut Rescue Air Pack (ARAP) and Emergency Egress Air Pack (EEAP)
Two designs for a lightweight, low profile, mobile rescue apparatus providing a 15-minute air supply and self-contained two-way communications assembly are described. Units are designed for astronaut use in hazardous environments
Comparing Optimal Relocation Operations With Simulated Relocation Policies in One-Way Carsharing Systems
One-way carsharing systems allow travelers to pick up a car at one station and return it to a different station, thereby causing vehicle imbalances across the stations. In this paper, a way to mitigate that imbalance is discussed, which is relocating vehicles between stations. For this purpose, two methods are presented, i.e., a new mathematical model to optimize the relocation operations that maximize the profitability of a carsharing service and a simulation model to study different real-time relocation policies. Both methods were applied to networks of stations in Lisbon, Portugal. Results show that relocating vehicles, using any of the methods developed, can produce significant increases in profit. For instance, in the case where the carsharing system provides maximum coverage of the city area, the imbalances in the network resulted in an operating loss of C1160/day when no relocation operations were performed. When relocation policies were applied, however, the simulation results indicate that profits of C854/day could be achieved, even with increased costs due to relocations. Using the mathematical model, the results are even better, with a reached profit of C3865.7/day. This improvement was achieved through reductions in the number of vehicles needed to satisfy the demand and the number of parking spaces needed at stations. These results demonstrate the importance of relocation operations for profitably providing a network of stations in one-way carsharing systems that covers the entire city, thus reaching a higher number of users
A Method for the Study of Human Factors in Aircraft Operations
A method for the study of human factors in the aviation environment is described. A conceptual framework is provided within which pilot and other human errors in aircraft operations may be studied with the intent of finding out how, and why, they occurred. An information processing model of human behavior serves as the basis for the acquisition and interpretation of information relating to occurrences which involve human error. A systematic method of collecting such data is presented and discussed. The classification of the data is outlined
Disaster Recovery—Managing immature crops for grain or silage
Tips on managing crops that may not mature before the first killing freeze of fall.https://lib.dr.iastate.edu/extension_ag_pubs/1203/thumbnail.jp
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Cost-effectiveness of community-based screening and treatment of moderate acute malnutrition in Mali.
IntroductionModerate acute malnutrition (MAM) causes substantial child morbidity and mortality, accounting for 4.4% of deaths and 6.0% of disability-adjusted life years (DALY) lost among children under 5 each year. There is growing consensus on the need to provide appropriate treatment of MAM, both to reduce associated morbidity and mortality and to halt its progression to severe acute malnutrition. We estimated health outcomes, costs and cost-effectiveness of four dietary supplements for MAM treatment in children 6-35 months of age in Mali.MethodsWe conducted a cluster-randomised MAM treatment trial to describe nutritional outcomes of four dietary supplements for the management of MAM: ready-to-use supplementary foods (RUSF; PlumpySup); a specially formulated corn-soy blend (CSB) containing dehulled soybean flour, maize flour, dried skimmed milk, soy oil and a micronutrient pre-mix (CSB++; Super Cereal Plus); Misola, a locally produced, micronutrient-fortified, cereal-legume blend (MI); and locally milled flour (LMF), a mixture of millet, beans, oil and sugar, with a separate micronutrient powder. We used a decision tree model to estimate long-term outcomes and calculated incremental cost-effectiveness ratios (ICERs) comparing the health and economic outcomes of each strategy.ResultsCompared to no MAM treatment, MAM treatment with RUSF, CSB++, MI and LMF reduced the risk of death by 15.4%, 12.7%, 11.9% and 10.3%, respectively. The ICER was US347 per DALY averted for RUSF compared with no MAM treatment.ConclusionMAM treatment with RUSF is cost-effective across a wide range of willingness-to-pay thresholds.Trial registrationNCT01015950
Pursuit of purity: Measurement of chelation binding affinities for NOTA, DOTA, and desferal with applications to effective specific activity
Introduction
The effective specific activity of a radioisotope is an indirect and highly useful way to describe a radioactive sample’s purity. A high effective specific activity combines the concept of an isotopically pure product with suitability via selectivity of a particular chelating body. The primary goals of this work are twofold: 1) To determine which metallic impurities have the largest impact on the effective specific activity for a given chelator, and 2) to form a model based on the binding affinities of each metal for to calculate a ‘theoretical effective specific activ-ity’ from broad band trace metal analysis. If successful, this information can be used to guide the production of high specific activity products through the systematic elimination of high-impact metallic impurities.
Material and Methods
Phosphor plate thin layer chromatography (TLC) was used to measure the effective specific activ-ity of 64Cu by NOTA and DOTA, and 89Zr by des-feral (DF). Typical measured effective specific activities are 2–5 Ci/μmol for 64Cu and 1–2 Ci/μmol for 89Zr.
Samples were created containing increasing cod competitive burdens (X) of CuCl2, ZnCl2, FeCl2, NiCl2, CrCl3, CoCl2, MnCl2, and YCl3. Standard concentrations were measured by microwave plasma atomic emission spectrometry. 50 pmol of NOTA, DOTA, or DF were added following the activity aliquots of 64Cu or 89Zr. Labeling efficien-cies (64Cu-NOTA, 64Cu-DOTA, 89Zr-DF) were measured using TLC’s, and were fit by linear regression to the form f(X) = b/(1 − AX), where A is the chelation affinity (inverse of dissociation constant) and X is the molar ratio of the metallic impurity to the amount of chelator.
Results and Conclusion
Affinity of Zr for DF was assumed to be unity, while the affinities of Cu for NOTA and DOTA were explicitly measured and were found to be 0.93 ± 0.13 and 5.2 ± 3.2 respectively.
It was found that Cu had the highest affinity for NOTA by a factor of 266, and that Zr had the highest affinity for DF by a factor of 40.
• In order of decreasing affinity to NOTA: Cu, Zn, Fe, Co, Cr, Y, and Ni
• In order of decreasing affinity to DOTA: Cu, Y, Zn, Co, Ni, Cr, and Fe
• In order of decreasing affinity to DF: Zr, Y, Cu, Zn, Ni, Fe, Co, Cr
These results suggest that aside from the carrier element it is most important to remove zinc from 64Cu products prior to chelation with NOTA and yttrium from 64Cu and 89Zr products prior to chelation with DOTA and DF, respectively. Therefore, it is logical to believe that 89Zr effective specific activities could be greatly improved by secondary separations with the goal of re-moving additional yttrium target material.
Chelation affinities of NOTA, DOTA, and DF for several common metals have successfully been investigated. These values will guide our future attempts to provide high effective specific activity 64¬Cu and 89Zr. Furthermore, a preliminary model has been formed to calculate effective specific activity from the quantitative broad band analysis of trace metals. Future work will include chelator affinity measurements for other likely contaminants, such as scandium, titanium, zirconium, molybdenum, niobium, gold, gallium, and germanium. Details will be presented
Winter grazing and pasture erosion
Winter precipitation, whether it\u27s rain, sleet, or snow, can lead to pasture erosion. Grazing livestock on frozen soil usually causes minimal pasture damage, but grazing pasture when soil is wet or muddy can lead to soil compaction, erosion, and long-term damage to pasture sod. Producers who manage livestock on pasture should consider the potential of soil erosion from winter grazing, particularly on sloped areas
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