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Selected AbstractsManagement and Recovery Options for Ural River Beluga SturgeonCONSERVATION BIOLOGY, Issue 3 2010PHAEDRA DOUKAKIS caviar; CITES; criadero; Mar Caspio; puntos de referencia; sobrepesca Abstract:,Management of declining fisheries of anadromous species sometimes relies heavily on supplementation of populations with captive breeding, despite evidence that captive breeding can have negative consequences and may not address the root cause of decline. The beluga sturgeon (Huso huso), a species threatened by the market for black caviar and reductions in habitat quality, is managed through harvest control and hatchery supplementation, with an emphasis on the latter. We used yield per recruit and elasticity analyses to evaluate the population status and current levels of fishing and to identify the life-history stages that are the best targets for conservation of beluga of the Ural River. Harvest rates in recent years were four to five times higher than rates that would sustain population abundance. Sustainable rates of fishing mortality are similar to those for other long-lived marine species such as sharks and mammals. Yield per recruit, which is maximized if fish are first harvested at age 31 years, would be greatly enhanced by raising minimum size limits or reducing illegal take of subadults. Improving the survival of subadult and adult females would increase population productivity by 10 times that achieved by improving fecundity and survival from egg to age 1 year (i.e., hatchery supplementation). These results suggest that reducing mortality of subadults and adult wild fish is a more effective conservation strategy than hatchery supplementation. Because genetics is not factored into hatchery management practices, supplementation may even reduce the viability of the beluga sturgeon. Resumen:,El manejo de pesquerías de peces anádromos en declinación a veces depende estrechamente de la suplementación de poblaciones mediante la reproducción en cautiverio, no obstante la evidencia de que la reproducción en cautiverio puede tener consecuencias negativas y no abordar la causa principal de la declinación. El esturión beluga (Huso huso), una especie amenazada por el mercado de caviar negro y por reducciones en la calidad del hábitat, es manejado mediante el control de la cosecha y suplementación de poblaciones, con énfasis en esta. Utilizamos análisis de producción por recluta y de elasticidad para evaluar el estatus de la población y los niveles de pesca actuales y para identificar las etapas de la historia de vida que son los mejores blancos para la conservación del beluga en el Río Ural. Las tasas de cosecha en años recientes fueron cuatro a cinco veces mayores que las tasas que sustentarían la abundancia de la población. Las tasas sustentables de mortalidad por pesca son similares a las de otras especies marinas longevas como tiburones y mamíferos. La producción por recluta, que es maximizada si los peces son cosechados a la edad de 31 años, podría incrementar significativamente elevando los límites de talla mínima o reduciendo la captura ilegal de subadultos. La mejora de la supervivencia de hembras subadultas y adultas incrementaría la productividad de la población 10 veces más que la mejora obtenida incrementando la fecundidad y supervivencia de huevo a 1 año de edad (i. e., suplementación de poblaciones mediante reproducción en cautiverio). Estos resultados sugieren que la reducción de la mortalidad de peces silvestres subadultos y adultos es una mejor estrategia de conservación que la suplementación. Debido a que la genética no es considerada en las prácticas de manejo en los criaderos, la suplementación incluso puede reducir la viabilidad del esturión beluga. [source] Refining Biodiversity Conservation PrioritiesCONSERVATION BIOLOGY, Issue 6 2005GRANT M. HARRIS Bosque del Atlántico; percepción remota; priorización; SIG; sitios prioritarios para la conservación Abstract:,Although there is widespread agreement about conservation priorities at large scales (i.e., biodiversity hotspots), their boundaries remain too coarse for setting practical conservation goals. Refining hotspot conservation means identifying specific locations (individual habitat patches) of realistic size and scale for managers to protect and politicians to support. Because hotspots have lost most of their original habitat, species endemic to them rely on what remains. The issue now becomes identifying where this habitat is and these species are. We accomplished this by using straightforward remote sensing and GIS techniques, identifying specific locations in Brazil's Atlantic Forest hotspot important for bird conservation. Our method requires a regional map of current forest cover, so we explored six popular products for mapping and quantifying forest: MODIS continuous fields and a MODIS land cover (preclassified products), AVHRR, SPOT VGT, MODIS (satellite images), and a GeoCover Landsat thematic mapper mosaic (jpg). We compared subsets of these forest covers against a forest map based on a Landsat enhanced thematic mapper. The SPOT VGT forest cover predicted forest area and location well, so we combined it with elevation data to refine coarse distribution maps for forest endemic birds. Stacking these species distribution maps enabled identification of the subregion richest in threatened birds,the lowland forests of Rio de Janeiro State. We highlighted eight priority fragments, focusing on one with finer resolved imagery for detailed study. This method allows prioritization of areas for conservation from a region >1 million km2 to forest fragments of tens of square kilometers. To set priorities for biodiversity conservation, coarse biological information is sufficient. Hence, our method is attractive for tropical and biologically rich locations, where species location information is sparse. Resumen:,Aunque hay acuerdo generalizado sobre las prioridades de conservación a escalas mayores (i. e., sitios prioritarios para la conservación de la biodiversidad), los límites son muy gruesos como para definir metas de conservación prácticas. La refinación de la conservación de sitios prioritarios significa la identificación de localidades específicas (parches de hábitat individuales) de tamaño y escala realistas para ser protegidos por gestores y apoyados por políticos. Debido a que los sitios prioritarios han perdido la mayor parte de su hábitat original, las especies endémicas dependen del que permanece. Ahora el asunto es identificar donde están el hábitat y las especies. Logramos lo anterior mediante técnicas directas de percepción remota y de SIG para identificar localidades específicas importantes para la conservación de aves en el sitio prioritario Bosque del Atlántico en Brasil. Nuestro método requiere de un mapa regional de la cobertura forestal actual, así que exploramos seis productos populares para el mapeo y cuantificación de bosques: campos continuos MODIS y una cobertura de suelo MODIS (productos preclasificados), AVHRR, SPOT VGT, MODIS (imágenes de satélite) y un mosaico GeoCover Landsat thematic mapper (jpg). Comparamos subconjuntos de estas coberturas forestales con las de un mapa basado en un Landsat enhanced thematic mapper. La cobertura forestal SPOT VGT predijo bien la superficie y localización del bosque, así que lo combinamos con datos de altitud para refinar los mapas generales de distribución de aves endémicas de bosques. La sobreposición de estos mapas de distribución permitió la identificación de la subregión más rica en aves amenazadas,los bosques en bajíos del Estado de Río de Janeiro. Dimos relevancia a ocho fragmentos prioritarios, con atención en uno con imágenes de resolución fina para estudio en detalle. Este método permite la priorización de áreas para conservación de fragmentos de decenas de kilómetros cuadrados en una región >1 millón km2. La información biológica general es suficiente para definir prioridades de conservación de la biodiversidad. Por lo tanto, nuestro método es atractivo para localidades tropicales y biológicamente ricas, para las que la información sobre la ocalización de las especies es escasa. [source] Exploiting the short,term and long,term channel properties in space and time: Eigenbeamforming concepts for the BS in WCDMAEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2001Christopher Brunner The deployment of adaptive antennas at base stations considerably increases the spectral efficiency of wireless communication systems. To reduce the computational complexity and increase performance of space,time (ST) processing, processing may take place in reduced dimension, i. e., pre,filtering takes place which is related to linear estimation theory based on second order statistics. To this end, long,term and short,term channel estimates are integrated into specific Tx/Rx systems. In this article, we present a new ST rake structure for uplink reception in WCDMA which operates in reduced dimension. Accordingly, our approach combines short,term and long,term spatial and temporal channel properties using an eigenanalysis. By choosing dominant eigenbeams in time and space, the algorithm enhances interference suppression as well as spatial and temporal receive diversity. In contrast to previously introduced well,known receiver structures, the ST eigenrake inherently adapts to different propagation environments and achieves higher spectral efficiency than other receivers. This is illustrated by Monte,Carlo simulations. Then we extend the proposed concept to the downlink. The downlink eigenbeamformer improves closed,loop downlink diversity compared to other proposals in standardization (3GPP) which only exploit short,term channel properties. Even though the short,term feedback rate remains unchanged, additional antenna elements can be included to increase antenna and diversity gain. We also present a tracking solution to the downlink eigenbeamforming in WCDMA. To this end, we propose a distributed implementation of the eigenspace/,beam tracking at the mobile terminal and base station (BS), respectively. Moreover, the specific nature of the deployed tracking scheme offers an advantageous feedback signalling. [source] Electrochemical Reduction of Oxygen on Carbon Supported Pt and Pt/Ru Fuel Cell Electrodes in Alkaline SolutionsFUEL CELLS, Issue 4 2003E.H. Yu Abstract A study of O2 reduction in 1 M NaOH solution at gas diffusion electrodes made from carbon supported Pt and Pt/Ru catalysts is reported. Two Tafel regions were observed for both the Pt and Pt/Ru electrodes. Although the same mechanism was suggested for oxygen reduction on both Pt and Pt/Ru catalysts, the O2 reduction activity was lower on Ru. Electrochemical Impedance Spectroscopy (EIS) analysis was carried out at different potentials and showed the significant contribution of diffusion on the reaction process and kinetics. The effect of methanol on O2 reduction was investigated in solutions containing various concentrations of methanol. The electrode performance deteriorated with increasing methanol concentration because of a mixed cathode potential. The methanol tolerance, i. e., the methanol concentration which polarises the O2 reduction reaction for O2 reduction, at the Pt/C electrode with a Pt loading of 1.2 mg cm,2 is 0.2 M methanol in 1 M NaOH. [source] Organizational Politics, Perceived Control, and Work Outcomes: Boundary Conditions on the Effects of Politics,JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 3 2001Dennis P. Bozeman This investigation examined the moderating influences of perceived control (i. e., personal control and job self-efficacy) on relationships between perceptions of organizational politics and organizational commitment, job satisfaction, intention to turnover, and job stress. Although results failed to support predictions concerning the interaction of perceptions of organizational politics and personal control, some support was found for predictions concerning the interactive influence of perceptions of organizational politics and job self-efficacy on outcomes. Data from 189 hotel managers supported the hypothesized interactive effects of perceptions of organizational politics and job self-efficacy for the outcomes of organizational commitment and job satisfaction. These results suggest that job self-efficacy exacerbates the relationship between perceived politics and certain dysfunctional attitudes. [source] Blurring Emotional Safety With Physical Safety in AIDS and STD Risk Estimations: The Casual/Regular Partner Distinction,JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 12 2000Lisa K. Comer Research on the sexual behavior of young adults has documented a casual/regular partner distinction in terms of condom use and perceived risk of contracting sexually transmitted diseases (STDs). How this population distinguishes between the 2 partner types has not been known, making it impossible to assess the rationality of this strategy. In the present study, college students' conceptions of casual vs. regular partners were explored and used to create 3 sexual partner scenarios: casual, regular with insufficient risk information (regular emotionally safe), and regular with sufficient risk information (regular objectively safe). Participants rated the target partner in terms of emotional safety, AIDS/STD risk, and likelihood of condom use. Results showed participants to be blurring emotional with physical safety; i. e., employing an emotionally based strategy in rating perceived risk. [source] Predictors of Teens' Attitudes Toward Condoms: Gender Differences in the Effects of NormsJOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 7 2000Yuko Mizuno Using data collected from a telephone survey of adolescents aged 15 to 19, we studied predictors of condom attitudes. Analyses were conducted on a sample of 348 sexually active teens. Multiple regression revealed that holding other variables constant being females, African American, perceiving that more of their friends were using condoms (i. e., perceived normative behavior). and stronger perceived normative pressure were significantly associated with favorable condom attitudes. Furthermore, significant interaction effects pointed to gender differences in the association between two types of norms and attitudes toward condoms. Perceived normative behavior had a greater effect on the attitudes of female adolescents. Perceived normative pressure had a greater effect on the attitudes of male adolescents. [source] Self-Supervisor Agreement: The Influence of Feedback Seeking on the Relationship Between Self and Supervisor Ratings of Performance,JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 2 2000JANE R. WILLIAMS Self-assessment research has continued to search for those factors that increase self-other rating agreement. The current field study investigated the feedback-seeking strategies (i. e., monitoring and inquiry) used by 125 employees to obtain performance information, as well as the relationship between feedback-seeking strategy use and self-supervisor performance-rating agreement. Results indicate that the frequency of monitoring reported by employees significantly moderated the relationship between self and supervisor ratings of performance. Individuals who reported higher levels of feedback seeking through monitoring were more likely to have self-assessments that were congruent with their supervisors' ratings of performance. [source] Natural resource-collection work and children's schooling in MalawiAGRICULTURAL ECONOMICS, Issue 2-3 2004Flora J. Nankhuni Abstract This paper presents results of research that investigates if long hours of work spent by children in fuel wood and water-collection activities, i. e., natural resource-collection work, influence the likelihood that a child aged 6,14 attends school. Potential endogeneity of resource-collection work hours is corrected for, using two-stage conditional maximum likelihood estimation. Data from the 1997,1998 Malawi Integrated Household Survey (IHS) conducted by the Malawi National Statistics Office (NSO) in conjunction with the International Food Policy Research Institute (IFPRI) are used. The study finds that Malawian children are significantly involved in resource-collection work and their likelihood of attending school decreases with increases in hours allocated to this work. The study further shows that girls spend more hours on resource-collection work and are more likely to be attending school while burdened by this work. Consequently, girls may find it difficult to progress well in school. However, girls are not necessarily less likely to be attending school. Results further show that presence of more women in a household is associated with a lower burden of resource-collection work on children and a higher probability of children's school attendance. Finally, the research shows that children from the most environmentally degraded districts of central and southern Malawi are less likely to attend school and relatively fewer of them have progressed to secondary school compared to those-from districts in the north. [source] DFT study and NBO analysis of the mutual interconversion of cumulene compoundsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2007Davood Nori-Shargh Abstract The B3LYP/6-31G* method was used to investigate the configurational properties of allene (1,2-propadiene) (1), 1,2,3-butatriene (2), 1,2,3,4-pentateriene (3), 1,2,3,4,5-hexapentaene (4), 1,2,3,4,5,6-heptahexaene (5), 1,2,3,4,5,6,7-octaheptaene (6), 1,2,3,4,5,6,7,8-nonaoctaene (7), and 1,2,3,4,5,6,7,8,9-decanonaene (9). The calculations at the B3LYP/6-31G* level of theory showed that the mutual interconversion energy barrier in compounds 1,8 are: 209.73, 131.77, 120.34, 85.00, 80.91, 62.19, 55.56, and 46.83,kJ,mol,1, respectively. The results showed that the difference between the average CC double bond lengths () values in cumulene compounds 1 and 2, is larger than those between 7 and 8, which suggest that with large n (number of carbon atoms in cumulene chain), the values approach a limiting value. Accordingly, based on the plotted data, the extrapolation to n,=,,, gives nearly the same limiting (i. e., ). Also, NBO results revealed that the sum of , -bond occupancies, , decrease from 1 to 8, and inversely, the sum of , -antibonding orbital occupancies, , increase from compound 1 to compound 8. The decrease of values for compounds 1,8, is found to follow the same trend as the barrier heights of mutual interconversion in compounds 1,8, while the decrease of the barrier height of mutual interconversion in compounds 1,8 is found to follow the opposite trend as the increase in the number of carbon atom. Accordingly, besides the previously reported allylic resonant stabilization effect in the transition state structures, the results reveal that the values, , ,(EHOMO,,,ELUMO), and the C atom number could be considered as significant criteria for the mutual interconversion in cumulene compounds 1,8. This work reports also useful predictive linear relationships between mutual interconversion energy barriers () in cumulene compounds and the following four parameters: , , ,(EHOMO,,,ELUMO), and CNumber. Copyright © 2007 John Wiley & Sons, Ltd. [source] Determination of the active metabolites of sibutramine in rat serum using column-switching HPLCJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2008So Young Um Abstract A simple and direct analysis using column-switching HPLC method was developed and validated for the quantification of active metabolites of sibutramine, N -mono-desmethyl metabolite (metabolite 1, M1) and N -di-desmethyl metabolite (metabolite 2, M2) in the serum of rats administered sibutramine HCl (5.0 mg/kg, p.o.). Rat serum was directly injected onto the precolumn without sample prepreparation step following dilution with mobile phase A, i. e., methanol,ACN,20 mM ammonium phosphate buffer (pH 6.0 with phosphoric acid) (8.3:4.5:87.2 by volume). After the endogenous serum components were eluted to waste, the system was switched and the analytes were eluted to the trap column. Active metabolites M1 and M2 were then back-flushed to the analytical column for separation with mobile phase B, i. e., methanol,ACN,20 mM ammonium phosphate buffer (pH 6.0 with phosphoric acid) (35.8:19.2:45 by volume) and detected at 223 nm. The calibration curves of active metabolites M1 and M2 were linear in the range of 0.1,1.0 ,g/mL and 0.15,1.8 ,g/mL. This method was fully validated and shown to be specific, accurate (10.4,10.7% error), and precise (1.97,8.79% CV). This simple and rapid analytical method using column-switching appears to be useful for the pharmacokinetic study of active metabolites (M1 and M2) of sibutramine. [source] Precision in differential field-flow fractionation: A chemometric studyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16 2007Letizia Bregola Abstract In the present paper, the capabilities of differential field-flow fractionation, i. e., the determination of an incremental quantity of a colloidal species, e. g., an uptake adsorbed mass, determined by the joint use of two independent FFF measurements, over a species and the same modified species respectively, are considered. The different error types, those related to the retention time determinations and those coming from the operating parameter fluctuations were considered. The different components were computed with reference to SdFFF determinations of bare polystyrene (PS) submicronic particles and the same PS particles covered by IgG. Comparison was made between theoretically computed precision and experiments. The error coming from the experimental measurement of retention times was identified to be the main source of errors. Accordingly, it was possible to make explicit the detection limits and the confidence intervals of the adsorbed mass uptake, as a function of experimental quantities such as the retention ratio, the detector calibration ratio, the injected quantity, the baseline noise, and the void time relative error. An experimentally determined and theoretically foreseen dependence of both the experimental detection and confidence limits (, ± 10,17 g) on the square root of the injected concentration, for constant injected volume, was found. [source] Acceleration of absolute negative mobilityJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2007Jan Regtmeier Abstract Recently, the counter intuitive migration phenomenon of absolute negative mobility (ANM) has been demonstrated to occur for colloidal particles in a suitably arranged post array within a microfluidic device [1]. This effect is based on the interplay of Brownian motion, nonlinear dynamics induced through microstructuring, and nonequilibrium driving, and results in a particle movement opposite to an applied static force. Simultaneously, the migration of a different particle species along the direction of the static force is possible [19], thus providing a new tool for particle sorting in microfluidic device format. The so far demonstrated maximum velocities for micrometer-sized spheres are slow, i. e., in the order of 10 nm per second. Here, we investigate numerically, how maximum ANM velocities can be significantly accelerated by a careful adjustment of the post size and shape. Based on this numerical analysis, a post design is developed and tested in a microfluidic device made of PDMS. The experiment reveals an order of magnitude increase in velocity. [source] Simple method for determination of five terpenoids from different parts of Tripterygium wilfordii and its preparations by HPLC coupled with evaporative light scattering detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2007Xiao-Ling Luo Abstract By optimizing the extraction, separation, and analytical conditions, a reliable and accurate high-performance liquid chromatography method coupled with evaporative light scattering detection (ELSD) was developed for simultaneous determination of five terpenoids, i. e., triptolide, tripchlorolide, demethylzelastral, wilforlide B, and wilforlide A, in root, stem, leaves, root bark, twig, and root without bark of Tripterygium wilfordii Hook. f and six of its herbal preparations. This approach would thus provide a more accurate and general method for evaluating the quality of the herb and its preparations. Separation of these five terpenoids was achieved on a ZORBAX Eclipse XDB-C8 column with gradient elution using water and acetonitrile as solvents, both containing 0.05% formic acid, at a temperature of 30°C and a flow rate of 0.8 mL/min. The drift tube temperature of ELSD was set at 100°C, and the nitrogen flow rate at 1.5 L/min. Good linear relationships were obtained with correlation coefficients for the analytes exceeding 0.992, and the LOD and LOQ were less than 0.149 ,g and 0.297 ,g on column, respectively. Intra-day and inter-day precision of the analytes were less than 1.25% and 5.97%, respectively, and the average recovery rates obtained were in the range of 95.9 ± 3.7% to 100.4 ± 5.0% for all terpenoids with RSDs below 4.99%. Quantitative analysis of the five terpenoids in different parts of Tripterygium wilfordii and its six preparations showed that the contents of the terpenoids varied significantly. The tender root contained higher concentrations of triptolide, tripchlorolide, demethylzelastral, and wilforlide B than any other part of the herb. Correspondingly, the root bark contained the greatest concentration of wilforlide A, and the stem and twig came in second and third. This suggested that we could infer whether the medicinal materials were absolute roots without bark or not from the comparative contents of these terpenoids in the tablets in view of the fact that only the roots without bark are the valid officinal part of the plant. This method and the quantitation results obtained can provide a scientific and general as well as simple and convenient approach for the product manufacturers to set up quality control standards and for informing the public about the quality and safety of the preparations. [source] Determination of the 2,3-pentadienedioic acid enantiomer interconversion energy barrier 1.JOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2006Classical kinetic approach Abstract A classical kinetic method was used to determine the energy barrier for the interconversion of 2,3-pentadienedioic acid enantiomers. Each individual enantiomer was isolated by collecting the appropriate peaks from the HPLC enantiomeric separation, of racemic 2,3-pentadienedioic acid. The isolated enantiomers were racemized at 22°C using various interconversion times. The ratio of enantiomers in each reaction solution was determined by HPLC at 22°C. The corresponding peak areas of the enantiomers and the interconversion times obtained from the HPLC chromatograms were used to calculate both the interconversion rate constants describing (+) , (,) and (,) , (+) interconversions as well as the energy barriers. It was confirmed that the interconversion of 2,3-pentadienedioic acid enantiomers is a first-order kinetic reaction. Both semiempirical and ab initio methods were used to explore the mechanism of the interconversion of 2,3-pentadienedioic acid enantiomers, and to calculate the interconversion energy barrier. Comparison of the interconversion energy barriers found by the ab initio method (,G# = 110.7 kJ/mol) and by classical kinetics in the mobile phase solution at 22°C (,Gapp = 93.9 ± 0.2 kJ/mol) shows a difference which may be attributed to the different conditions assumed in the theoretical calculation (i. e., a gaseous state) and the actual experimental conditions (i. e., liquid solution) and a possible catalytic effect of the solution composition. [source] Comparison of two capillary electrophoresis online stacking modes by analysis of polycyclic aromatic hydrocarbons in airborne particulatesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2006Guan-Qun Song Abstract Naphthalene, fluorene, pyrene, anthracene, phenanthrene, and chrysene were successfully separated by CD-modified MEKC (CD-MEKC) using 20 mM borate (pH 9.0) containing 90 mM SDS and 75 mM ,-CD. Two online stacking methods, i. e., sweeping and field-enhanced sample injection (FESI), were explored to enhance the detection sensitivity. The influences of some crucial parameters in sweeping and FESI procedures were investigated. For FESI method, a plug of water and low-conductivity sample matrix was used to increase the stacking efficiency. Compared with the sweeping method, FESI can increase the sensitivity in the range of 10,20-fold. The proposed method was used for the analysis of polycyclic aromatic hydrocarbons in airborne particulates. [source] Prediction of chromatographic relative retention time of polychlorinated biphenyls from the molecular electronegativity distance vectorJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2006Shu-Shen Liu Abstract Using the molecular electronegativity distance vector (MEDV) descriptors derived directly from the molecular topological structures, the gas chromatographic relative retention times (RRTs) of 209 polychlorinated biphenyls (PCBs) on the SE-54 stationary phase were predicted. A five-variable regression equation with the correlation coefficient of 0.9964 and the root mean square errors of 0.0152 was developed. The descriptors included in the equation represent degree of chlorination (nCl), nonortho index (Ino), and interactions between three pairs of atom types, i. e., atom groups ,C= and ,C=, ,C= and >C=, ,C= and ,Cl. It has been proved that the retention times of all 209 PCB congeners can be accurately predicted as long as there are more than 50 calibration compounds. In the same way, the MEDV descriptors are also used to develop the five- or six-variable models of RRTs of PCBs on other 18 stationary phases and the correlation coefficients in both modeling stage and LOO cross-validation step are not lower than 0.99 except two models. [source] Absolute enantioselective separation: Optical activity ex machinaJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2005Roman Bielski Abstract The paper describes methodology of using three independent macroscopic factors affecting molecular orientation to accomplish separation of a racemic mixture without the presence of any other chiral compounds, i. e., absolute enantioselective separation (AES) which is an extension of a concept of applying these factors to absolute asymmetric synthesis. The three factors may be applied simultaneously or, if their effects can be retained, consecutively. The resulting three mutually orthogonal or near orthogonal directors constitute a true chiral influence and their scalar triple product is the measure of the chirality of the system. AES can be executed in a chromatography-like microfluidic process in the presence of an electric field. It may be carried out on a chemically modified flat surface, a monolithic polymer column made of a mesoporous material, each having imparted directional properties. Separation parameters were estimated for these media and possible implications for the natural homochirality are discussed. [source] Pesticide analysis by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2004J. Hernández-Borges Abstract In this work, a critical and updated revision of the current situation of the analysis of pesticides by Capillary Electrophoresis (CE) is presented. The review has been written in two main sections. The first one presents a thorough revision of the various off-line and on-line sample preconcentration procedures that have been used in conjunction with CE to analyze these compounds. The second part reviews the various detection strategies (i. e., UV, LIF, MS, and electrochemical) and CE modes that have been applied to the analysis of pesticides. Future trends that can be expected from this hot research area are also discussed. [source] Validation of a quantitative assay using GC/MS for trace determination of free and conjugated estrogens in environmental water samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2003Asmaa Mouatassim-Souali Abstract It has been shown that sewage effluent can discharge human hormones and pharmaceuticals, particularly estrogens and synthetic chemicals, which are able to disrupt animal and human endocrine systems into surface waters. Since many surface waters receive sewage effluent and are subsequently used to produce drinking water, it is of principal interest to assess their contamination level and thereby their possible public health and environmental impact. To date, no data concerning the occurrence of estrogens present in the French aquatic environment are available. We therefore developed and validated an analytical procedure, which allows simultaneous quantitative determination of three natural estrogens, 17,-estradiol, estriol, and estrone and one of the synthetic estrogens most widely used in contraception, ethinylestradiol, in water. Water samples are extracted using solid-phase extraction (SPE) and then separated by gas-chromatography coupled with mass spectrometric detection. Under our conditions, detection limits of estrogens reached the pg range of injected sample, i. e. less than 0.1 ng L,1. Conjugated estrogens were also investigated using the same procedure as described above but with a enzymatic hydrolysis preliminary step before extraction. The analysis of samples collected from four wastewater treatment plants and from surface water showed significant concentrations of estrogens ranging from 2 to 18 ng L,1 and from 0.5 to 3 ng L,1, respectively. Furthermore, no estrogen conjugated forms were detected in the water samples. [source] COMPARISON OF PHYSICAL PROPERTIES OF AGAR, LOW GEL STRENGTH AGAR AND GELATIN, AS SUPPLEMENTARY FOOD FOR PEOPLE WITH SWALLOWING DIFFICULTYJOURNAL OF TEXTURE STUDIES, Issue 4 2002ATSUKO IGARASHI ABSTRACT Low gel strength agar (LGSA), recently developed as a supplementary food for swallowing was compared with ordinary agar and gelatin. LGSA was developed to have physical properties close to that of gelatin, while keeping one property of agar, i. e. its setting temperature which can be controlled comparatively easier than gelatin. Each specimen was prepared with and without orange flavor. After determination of their basic properties, i. e. hardness, adhesiveness, cohesiveness and gumminess, three samples of two flavors, six in all, were studied for ease of swallowing using electromyography and sensory evaluation, on middle age (40 to 60 years old) and senior age (60 to 70 years old) subjects. Those experiments revealed nearly the same results with all samples, except for a slight difference in gumminess in LGSA and gelatin. No significant difference in electromyograms were noted in six samples or with age of subjects. It is feasible to employ agar materials together with gelatin in institutions whose members have swallowing disorders. [source] APPLICATION OF A COMPRESSION-RELAXATION TEST FOR THE CHARACTERIZATION OF BURLAT SWEET CHERRYJOURNAL OF TEXTURE STUDIES, Issue 1 2001PEDRO L. MARQUINA Mechanical parameters of Burlat sweet cherries (Prunus avium) were studied as a function of ripening during three consecutive years by using a penetration test, a compression test between two plates, and a compression-relaxation test. The latter yields the "apparent secant modulus," i. e. the ratio of the initial maximum compression force over the applied strain. This modulus is one of the most useful mechanical parameters to discriminate between batches because its value is clearly related to the variety and degree of ripeness. Thus, the compression-relaxation test consistently allowed the differentiation of cherries in five degrees of ripeness. [source] A method for the tribological testing of thin, hard coatingsLUBRICATION SCIENCE, Issue 2 2002R. Michalczewski Abstract A new method has been developed for tribological testing of thin, hard antiwear coatings, using a ball-on-disc tribosystem, under conditions of dry sliding. In this, an Al2O3 ball is pressed against a coated steel disc. Wear debris is removed from the contact zone by a stream of dry argon in this novel method. This improves the stability of the tribological properties and the repeatability of the test results. All test conditions are precisely defined, in particular: the type of motion, air relative humidity, ambient temperature, sliding speed, load, tribosystem spatial configuration, substrate material, substrate hardness and roughness, and coating thickness. The method developed has been used to test various physical vapour deposition coatings (deposited by the vacuum arc method), i. e., single-layer TiN, Ti(C,N), CrN, and Cr(C,N), and multilayer Cr(C,N)/CrN/Cr and Cr(C,N)/(CrN+Cr2N)/CrN/Cr. It is shown that CrN coatings exhibit the best antiwear properties, and Ti(C,N) the worst. Friction coefficients for CrN and Cr(C,N) coatings are much lower than for the more commonly used TiN. Multilayer coatings have better antiwear properties than single-layer ones. [source] Abundance, Tidal Movement, Population Structure and Burrowing Rate of Emerita analoga (Anomura, Hippidae) at a Dissipative and a Reflective Sandy Beach in South Central ChileMARINE ECOLOGY, Issue 2 2000Eduardo Jaramillo Abstract. To evaluate the effects of beach morphodynamics upon the abundance, tidal movement, population structure and burrowing rate of the crab Emerita analoga (Stimpson) (Anomura, Hippidae) we sampled two beaches in south central Chile (ca. 42° S), Mar Brava and Ahui with dissipative and reflective characteristics, respectively. The swash zone at the dissipative beach was 5,,,6 times wider than that of the reflective beach. A at the dissipative beach, upwash speeds were higher and the number of effluent line crossings were lower by more than an order of magnitude. To examine the tidal movement of E. analoga, we collected crabs from 5 to 6 tidal levels of each beach every 2 h across 12 h of the tidal cycle. The intertidal distribution of crabs differed between beaches; i. e., at the dissipative beach they were primarily located at the swash zone, while at the reflective beach they were mostly located at the low tide level and shallow subtidal. The change in position of crabs was pronounced across the tidal cycle at the dissipative beach (Mar Brava), with most of the animals remaining in the active swash zone. Body size data were used to construct size frequency distributions for each population. Crabs from the dissipative beach reached larger sizes than those at the reflective beach. Sediments were coarser at the latter versus the former beach. Crabs burrowed at similar rates in the sand from both beaches, a result which supports the idea that E. analoga is a "sediment generalist" capable of burrowing successfully in a wide range of sediment types. This characteristic is likely a key to the broad success of this species on the full range of beach morphodynamic types along the coasts of South and North America. [source] MOLECULAR SYSTEMATICS OF RIVER DOLPHINS INFERRED FROM COMPLETE MITOCHONDRIAL CYTOCHROME- B GENE SEQUENCESMARINE MAMMAL SCIENCE, Issue 1 2002Guang Yang Abstract 1,140 bp of the complete mitochondrial cytochrome- b gene sequences of baiji (Lipotes vexillifer), franciscana (Pontoporia blainvillei), and Ganges river dolphin (Platanista gangetica gangetica) were determined to address the systematic position and phylogeny of extant river dolphins with combination of homologous sequences of other cetaceans. The neighbor-joining (NJ), maximum parsimony (MP), and maximum likelihood (ML) phylogenetic analyses all identified the river dolphins into three lineages, i. e., Platanista, Lipotes, and Inia+Pontoporia. The Lipotes did not have sister relationship with either Platanista or Inia+Pontoporia, which strongly supported the referral of Lipotes to a separate family, i. e., Lipotidae. There were very high sequence divergences between all river dolphin genera, suggesting a relatively longer period of separation time than those among other odontocete families. [source] DIET-TISSUE FRACTIONATION OF STABLE CARBON AND NITROGEN ISOTOPES IN PHOCID SEALSMARINE MAMMAL SCIENCE, Issue 1 2002VÉRONIQUE Lesage Diet-tissue isotopic fractionation of carbon (C) and nitrogen (N) isotopes in short- and longer-term diet integrators of diet (i. e., blood serum and red cells), that involve non-invasive sampling techniques was examined using three species of phocid seals (harbor seals, gray seals, and harp seals) fed a known diet. Variability in diet-tissue fractionation values within and between species was also scrutinized to determine the legitimacy of using values obtained from one species to explore trophic positions and diets of other related species. All captive seals raised on a constant diet had tissues enriched in 13C and 15N relative to their diet. Diet-tissue isotopic fractionation values were generally consistent among conspecifics and among phocid species for a given tissue. Trophic isotopic enrichment in 13C was significantly higher in red blood cells (+1.5%±) than in blood serum (+0.8%±), whereas the reverse was observed for nitrogen isotopes (+1.7%± in red cells vs. +3.1%± in serum). However, 13C-depleted lipids were not extracted from blood tissues in this study. This results in a downward bias in the diet-tissue fractionation factors for carbon for both red cells and blood serum, particularly the latter because of their significantly higher lipid contents (x,± SD = 14.6 ± 2.3%; n= 20; red blood cells 3.8 ± 0.9%±; n= 50, muscle 7.7 ± 2.0; n= 21) in marine mammals. [source] COLLISIONS BETWEEN SHIPS AND WHALESMARINE MAMMAL SCIENCE, Issue 1 2001David W. Laist Abstract Although collisions with motorized ships are a recognized source of whale mortality, little has been done to compile information on the frequency of their occurrence or contributing factors. We searched historical records and computerized stranding databases for evidence of ship strikes involving great whales (i. e., baleen whales and the sperm whale). Historical records suggest that ship strikes fatal to whales first occurred late in the 1800s as ships began to reach speeds of 13-15 kn, remained infrequent until about 1950, and then increased during the 1950s-1970s as the number and speed of ships increased. Of 11 species known to be hit by ships, fin whales (Balaenoptera physalus) are struck most frequently; right whales (Eubalaena glacialis and E. australis), humpback whales (Megaptera novaeangliae), sperm whales (Physeter catodon), and gray whales (Escbricbtius robustus) are hit commonly. In some areas, one-third of all fin whale and right whale strandings appear to involve ship strikes. To assess contributing factors, we compiled descriptions of 58 collisions. They indicate that all sizes and types of vessels can hit whales; most lethal or severe injuries are caused by ships 80 m or longer; whales usually are not seen beforehand or are seen too late to be avoided; and most lethal or severe injuries involve ships travelling 14 kn or faster. Ship strikes can significantly affect small populations of whales, such as northern right whales in the western North Atlantic. In areas where special caution is needed to avoid such events, measures to reduce the vessel speed below 14 kn may be beneficial. [source] Metal dusting resistance of high chromium alloysMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2003H. J. Grabke Metal dusting; hoch Chromhaltige Legierungen; Chromoxidschicht; Aufkohlung Abstract Samples of 5 high Cr-alloys were discontinuously exposed for 10,000 hours under severe metal dusting conditions, i. e. in flowing 49%CO-49%H2 -2%H2O at 650°C. After each of the 11 exposure periods the mass change was determined and any coke removed and weighed. Metallographic cross sections were prepared after about 4,000 h and 10,000 h. The high Cr-alloys: 1. PM 2000 (Fe-19%Cr-5.5%Al-0.5%Ti-0.5%Y2O3), 2. Cr-44%Fe-5%Al-0.4%Ti-0.5%Y2O3, 3. Cr-50%Ni, 4. Cr-5%Fe-1%Y2O3 and 5. porous chromium showed no or only minute metal dusting attack. Compared to the attack on reference samples of Alloy 601 (Ni-23%Cr-14%Fe-1.4%Al), the metal dusting symptoms were negligible on the 5 high Cr-alloys, minor coking and pitting and no internal carburization was observed. Because of the high Cr-content, carbon solution and ingress should be minute, and in addition are inhibited by the formation of a chromia scale, as confirmed for four of the Cr-rich alloys, and formation of an alumina scale on PM 2000. These alloys could be used for parts exposed to severe metal dusting conditions, and in fact, 50Cr-50Ni has been applied successfully under such conditions. [source] Residuated lattices arising from equivalence relations on Boolean and Brouwerian algebrasMLQ- MATHEMATICAL LOGIC QUARTERLY, Issue 4 2008Thomas Vetterlein Abstract Logics designed to deal with vague statements typically allow algebraic semantics such that propositions are interpreted by elements of residuated lattices. The structure of these algebras is in general still unknown, and in the cases that a detailed description is available, to understand its significance for logics can be difficult. So the question seems interesting under which circumstances residuated lattices arise from simpler algebras in some natural way. A possible construction is described in this paper. Namely, we consider pairs consisting of a Brouwerian algebra (i. e. a dual Heyting algebra) and an equivalence relation. The latter is assumed to be in a certain sense compatible with the partial order, with the formation of differences, and with the formation of suprema of pseudoorthogonal elements; we then call it an s-equivalence relation. We consider operations which, under a suitable additional assumption, naturally arise on the quotient set. The result is that the quotient set bears the structure of a residuated lattice. Further postulates lead to dual BL-algebras. In the case that we begin with Boolean algebras instead, we arrive at dual MV-algebras. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Computability of solutions of operator equationsMLQ- MATHEMATICAL LOGIC QUARTERLY, Issue 4-5 2007Volker Bosserhoff Abstract We study operator equations within the Turing machine based framework for computability in analysis. Is there an algorithm that maps pairs (T, u) (where T is given in form of a program) to solutions of Tx = u ? Here we consider the case when T is a bounded linear mapping between Hilbert spaces. We are in particular interested in computing the generalized inverse T,u, which is the standard concept of solution in the theory of inverse problems. Typically, T, is discontinuous (i. e. the equation Tx = u is ill-posed) and hence no computable mapping. However, we will use effective versions of theorems from the theory of regularization to show that the mapping (T, T *, u, ,T,u ,) , T,u is computable. We then go on to study the computability of average-case solutions with respect to Gaussian measures which have been considered in information based complexity. Here, T, is considered as an element of an L2 -space. We define suitable representations for such spaces and use the results from the first part of the paper to show that (T, T *, ,T,,) , T, is computable. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||||||||