5,541 research outputs found
Cold inelastic collisions between lithium and cesium in a two-species magneto-optical trap
We investigate collisional properties of lithium and cesium which are
simultaneously confined in a combined magneto-optical trap. Trap-loss
collisions between the two species are comprehensively studied. Different
inelastic collision channels are identified, and inter-species rate
coefficients as well as cross sections are determined. It is found that loss
rates are independent of the optical excitation of Li, as a consequence of the
repulsive Li-Cs interaction. Li and Cs loss by inelastic inter-species
collisions can completely be attributed to processes involving optically
excited cesium (fine-structure changing collisions and radiative escape). By
lowering the trap depth for Li, an additional loss channel of Li is observed
which results from ground-state Li-Cs collisions changing the hyperfine state
of cesium.Comment: submitted to Euro. Phys. J. D, special issue on Laser Cooling and
Trappin
Seed dispersal distances: a typology based on dispersal modes and plant traits
The ability of plants to disperse seeds may be critical for their survival under the current constraints of landscape fragmentation and climate change. Seed dispersal distance would therefore be an important variable to include in species distribution models. Unfortunately, data on dispersal distances are scarce, and seed dispersion models only exist for some species with particular dispersal modes. To overcome this lack of knowledge, we propose a simple approach to estimate seed dispersal distances for a whole regional flora. We reviewed literature about seed dispersal in temperate regions and compiled data for dispersal distances together with information about the dispersal mode and plant traits. Based on this information, we identified seven "dispersal types" with similar dispersal distances. For each type, upper limits for the distance within which 50% and 99% of a species' seeds will disperse were estimated with the 80th percentile of the available values. These distances varied 5000-fold among the seven dispersal types, but generally less than 50-fold within the types. Thus, our dispersal types represented a large part of the variation in observed dispersal distances. The attribution of a dispersal type to a particular species only requires information that is already available in databases for most Central European species, i.e. dispersal vector (e.g. wind, animals), the precise mode of dispersal (e.g. dyszoochory, epizoochory), and species traits influencing the efficiency of dispersal (e.g. plant height, typical habitats). This typology could be extended to other regions and will make it possible to include seed dispersal in species distribution models
Risk preferences estimation for small raspberry producers in the Bio-Bio Region, Chile
Toledo, R (reprint author), Ctr Reg Invest Quilamapu, Inst Invest Agropecuarias, Casilla 426, Chillan, ChileDecisions are strongly influenced by Ask and Ask preferences or decision makes; however, in Chile there are few studies in Me agricultural sector focused on this topic. The present paper analyzes the risk preferences of small producers or raspberries (Win idaeus L.) and the production function associated with their production system in the Bio-Bio Region of Chile. Under a mean-variance approach, the estimation procedure uses a flexible utility Function to incorporate a variety of risk preference alternatives. Three different estimation procedures were used: Least Squares Estimation, Seemingly Unrelated Regression and Full Information Maximum Likelihood, which revealed Me same Conclusions. Results showed that small farmers are risk averse (gamma=0.104) and present increasing relative and absolute aversion to risk (theta =0.099 < 1 and theta < gamma, respectively). The hypotheses of risk neutrality (gamma = 0) and constant absolute risk aversion (theta = 1) were rejected with 94% and 99% confidence, respectively. The chosen function of production is the Cobb Douglas type, because A presents a better adjustment, and the relevant factors are fertilizer quantity per hectare, the experience of the producer and the planted area. This Function presents decreasing returns to scale, then beta(2)+beta(3)+beta(4) is equal to 0.18. The hypothesis of constant returns to scale is rejected with 99%, confidence
α2 High molecular mass cysteine proteinase inhibitor: HMrα2-CPI An inhibitor of human liver cathepsin H as probed by kinetic study
AbstractHMrα2CPI was found to be an inhibitor of human liver cathepsin H by the measurement of the dissociation constant (Ki), the association rate constant (k1) and the dissociation rate constant (k−1) between the enzyme and the inhibitor. These data suggest that this protein-proteinase inhibitor can play a physiological role in the regulation of free cathepsin H
Evaluation of Risk Factors in Agriculture: An Application of the Analytical Hierarchical Process (AHP) Methodolog
Engler, A (reprint author), Univ Talca, Fac Ciencias Agr, Av Lircay S-N, Talca, Chile.Risk in the agricultural sector has multiple dimensions or factors and prioritization of these can support decision making. On the other hand, knowing the importance of these risk factors for distinct agricultural activities and how they vary according to geographic zone constitutes relevant information for agricultural development. The objective of this study was to prioritize risk factors that are highly relevant for farmers in Central South Chile. The multicriteria Analytical Hierarchical Process (AHP) methodology was used to define a decision structure with four risk factors or criteria: climate, price and direct cost variability, human factor, and commercialization. In general, results obtained showed that there are no important imbalances in the weightings of different risk factors. Price and cost variability was the most important factor (0.30) whereas climate was the least important (0.20). It also confirmed that there are spatial differences in the weightings obtained for the distinct risk factors which determine distinct risk levels for the respective agricultural activities according to geographic region
Development and test of advanced composite components. Center Directors discretionary fund program
This report describes the design, analysis, fabrication, and test of a complex bathtub fitting. Graphite fibers in an epoxy matrix were utilized in manufacturing of 11 components representing four different design and layup concepts. Design allowables were developed for use in the final stress analysis. Strain gage measurements were taken throughout the static load test and correlation of test and analysis data were performed, yielding good understanding of the material behavior and instrumentation requirements for future applications
Application of nuclear volume measurements to comprehend the cell cycle in root-knot nematode-induced giant cells.
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Previous issue date: 2017-08-1
The United States Army Corps of Engineers\u27 Perspective on Environmental Dredging
This paper summarizes investigations conducted under the Dredged Material Research Program, Long-Term Effects of Dredging Operations Program, Field Verification Program, Dredging Operations Technical Support Program, and field reimbursable work funded by the U. S. Army Corps of Engineers. Permission to publish this material was granted by the U.S. Army Corps of Engineers, Chief of Engineers
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