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Retention Process (retention + process)
Selected AbstractsReview of Pesticide Retention Processes Occurring in Buffer Strips Receiving Agricultural Runoff,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2010Kapil Arora Arora, Kapil, Steven K. Mickelson, Matthew J. Helmers, and James L. Baker, 2010. Review of Pesticide Retention Processes Occurring in Buffer Strips Receiving Agricultural Runoff. Journal of the American Water Resources Association (JAWRA) 46(3):618-647. DOI: 10.1111/j.1752-1688.2010.00438.x Abstract:, Review of the published results shows that the retention of the two pesticide carrier phases (runoff volume and sediment mass) influences pesticide mass transport through buffer strips. Data averaged across different studies showed that the buffer strips retained 45% of runoff volume (ranging between 0 and 100%) and 76% of sediment mass (ranging between 2 and 100%). Sorption (soil sorption coefficient, Koc) is one key pesticide property affecting its transport with the two carrier phases through buffer strips. Data from different studies for pesticide mass retention for weakly (Koc < 100), moderately (100 < Koc < 1,000), and strongly sorbed pesticides (Koc > 1,000) averaged (with ranges) 61 (0-100), 63 (0-100), and 76 (53-100) %, respectively. Because there are more data for runoff volume and sediment mass retention, the average retentions of both carrier phases were used to calculate that the buffer strips would retain 45% of weakly to moderately sorbed and 70% of strongly sorbed pesticides on an average basis. As pesticide mass retention presented is only an average across several studies with different experimental setups, the application of these results to actual field conditions should be carefully examined. [source] Brief analysis of the retention process in RP-HPLC systems with a C30 bonded stationary phaseJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2008Wojciech Zapa Abstract The influence of the mobile-phase composition on the retention of eight model substances in different RP-HPLC systems with a C30 alkyl bonded stationary phase has been studied. The aim of this study was to compare the performance of four valuable retention models assuming the partition and adsorption mechanism of retention. All the models were verified for different experimental data by four criteria: the sum of squared differences between the experimental and theoretical data; the approximation of the standard deviation; the Fisher test; and the F-test ratio. [source] Rural Illinois Hospital Chief Executive Officers' Perceptions of Provider Shortages and Issues in Rural Recruitment and RetentionTHE JOURNAL OF RURAL HEALTH, Issue 1 2006Michael Glasser PhD ABSTRACT:,Background: It is important to assess rural health professions workforce needs and identify variables in recruitment and retention of rural health professionals. Purpose: This study examined the perspectives of rural hospital chief executive officers (CEOs) regarding workforce needs and their views of factors in the recruitment and retention process. Methods: A survey was mailed to CEOs of 28 Illinois rural hospitals, in towns ranging from 3,396 to 33,530 in population size. The survey addressed CEO perceptions of number of physicians needed by specialty, need for other health professionals, and variables important to recruitment and retention. Findings: Twenty-two CEOs (79%) responded to the survey. Eighty-six percent indicated a physician shortage in the community, with 64% reporting the need for family physicians. CEOs also indicated the need for physicians in obstetrics-gynecology, general and orthopedic surgery, general internal medicine, cardiology, and psychiatry. In terms of needs for other health professionals, most often mentioned were registered nurses (91%), pharmacists (64%), and nurses' aides (46%). Related to recruitment and retention, most often mentioned by the CEOs was community attractiveness in general, followed by practice and physician career opportunities. Conclusions: CEOs offer 1 important perspective on health professions needs, recruitment, and retention in rural communities. While expressing a range of opinions, rural hospital CEOs clearly indicate the need for more primary care physicians, call for an increased capacity in nursing, and point to community development as a key factor in recruitment and retention. [source] Characterization of an Area Polluted by Copper and Zinc: the Relation between Soil Texture, Mineralogy and Pollutant ConcentrationACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 6 2009Caterina RINAUDO Abstract: Twenty-four soil samples were collected at three depths from an approximately 2.5 acre contaminated site in southern Piedmont (Italy) and then analyzed. The main soil parameters determined were: pH, Cation Exchange Capacity (CEC), particle size distribution, total organic carbon (TOC) content and retained metal concentration. The mineral phases were identified by X-Ray Powder Diffraction (XRPD). All of the samples contained Zn and Cu resulting from industrial contamination during the last century, and those obtained at depths of 20,40 cm consistently showed the highest levels. To determine which size fraction was most active in the retention process, the samples were separated into four fractions (,2 mm, ,63 ,m, ,30 ,m and ,2 ,m) and the amount of pollutant measured in each. It was found that metal retention was the highest in the clayey fraction, whose clay minerals were identified by XRPD after K+ and Mg2+ saturation, glycerol treatment and heating to 550° C. The clayey fraction was also the richest in TOC, and a direct correlation between TOC amount and metal retention was observed. [source] Modeling knowledge-based inferences in story comprehensionCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 6 2003Stefan L. Frank Abstract A computational model of inference during story comprehension is presented, in which story situations are represented distributively as points in a high-dimensional "situation-state space." This state space organizes itself on the basis of a constructed microworld description. From the same description, causal/temporal world knowledge is extracted. The distributed representation of story situations is more flexible than Golden and Rumelhart's [Discourse Proc 16 (1993) 203] localist representation. A story taking place in the microworld corresponds to a trajectory through situation-state space. During the inference process, world knowledge is applied to the story trajectory. This results in an adjusted trajectory, reflecting the inference of propositions that are likely to be the case. Although inferences do not result from a search for coherence, they do cause story coherence to increase. The results of simulations correspond to empirical data concerning inference, reading time, and depth of processing. An extension of the model for simulating story retention shows how coherence is preserved during retention without controlling the retention process. Simulation results correspond to empirical data concerning story recall and intrusion. [source] Simulation and quantification of enrichment and retention processes in the southern Benguela upwelling ecosystemFISHERIES OCEANOGRAPHY, Issue 5 2006CHRISTOPHE LETT Abstract Important environmental processes for the survival and recruitment of early life stages of pelagic fishes have been synthesized through Bakun's fundamental triad as enrichment, concentration and retention processes (A. Bakun, 1996, Patterns in the Ocean. Ocean Processes and Marine Population Dynamics. San Diego, CA, USA: University of California Sea Grant). This conceptual framework states that from favourable spawning habitats, eggs and larvae would be transported to and/or retained in places where food originating from enrichment areas would be concentrated. We propose a method for quantifying two of the triad processes, enrichment and retention, based on the Lagrangian tracking of particles transported within water velocity fields generated by a three-dimensional hydrodynamic model. We apply this method to the southern Benguela upwelling ecosystem, constructing putative maps of enrichment and retention. We comment on these maps regarding main features of the circulation in the region, and investigate seasonal variability of the processes. We finally discuss the results in relation to available knowledge on the reproductive strategies of two pelagic clupeoid species abundant in the southern Benguela, anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax). Our approach is intended to be sufficiently generic so as to allow its application to other upwelling systems. [source] |