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Approach Shows (approach + shows)
Selected AbstractsDispersion of Dust Acoustic Modes and Perturbations of Plasma Flux BalanceCONTRIBUTIONS TO PLASMA PHYSICS, Issue 3 2007V. Tsytovich Abstract Previous considerations of dust acoustic waves is demonstrated to be inconsistent - the required equilibrium state for perturbations was not defined since balance of plasma fluxes was neglecting. The self-consistent treatment shows that plasma flux perturbations are accompanying any collective waves propagating in dusty plasmas and can play an important role in wave dispersion, wave damping and can create instabilities. This is illustrated by the derivation of dispersion relation for dust acoustic modes taking into account the plasma flux balances and plasma flux perturbations by waves. The result of this approach shows that the dust acoustic waves with linear dependence of wave frequency on the wave number exist only in restricted range of the wave numbers. Only for wave numbers larger than some critical wave number for low frequency modes the frequency can be have approximately a linear dependence on wave number and can be called as dust acoustic wave but the phase velocity of these waves is different from that which can be obtained neglecting the flux balance and depends on grain charge variations which are determined by the balance of fluxes. The presence of plasma fluxes previously neglected is the main typical feature of dusty plasmas. The dispersion relation in the range of small wave numbers is found to be mainly determined by the change of the plasma fluxes and is quite different from that of dust acoustic type, namely it is found to have the same form as the well known dispersion relation for the gravitational instability. This result proves in general way the existence of the collective grain attractions of negatively charged grains for for large distances between them and for any source of ionization. The attraction of grains found from dispersion relation of the dust acoustic branch coincides with that found previously for pair grain interactions using some models for the ionization source. For the existing experiments the effective Jeans length for such attraction is estimated to be about 8 , 10 times larger than the ion Debye length and the effective gravitational constant for the grain attraction is estimated to be several orders of magnitude larger than the usual gravitational constant. The grain attraction at large inter-grain distances described by the gravitationlike grain instability is considered as the simplest explanation for observed dust cloud clustering, formation of dust structures including the plasma crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Genetic pattern of the recent recovery of European otters in southern FranceECOGRAPHY, Issue 2 2008Xavier Janssens We investigated how landscape affects the population genetic structure and the dispersal of the elusive European otter Lutra lutra in a contemporary colonization context, over several generations and at the level of hydrographic basins. Our study area included 10 basins located in the Cévennes National Park (CNP), at the southern front of the natural otter recovery in France. Each basin comprised 50 to 300 km of permanent rivers that were surveyed for otter presence from 1991 to 2005. Faecal samples collected in 2004 and 2005 in this area were genotyped at 9 microsatellite loci, resulting in the identification of 70 genetically distinct individuals. Bayesian clustering methods were used to infer genetic structure of the populations and to compare recent gene flow to the observed colonization. At the regional level, we identified 2 distinct genetic clusters (NE and SW; FST=0.102) partially separated by ridges, suggesting that the CNP was recolonized by 2 genetically distinct otter populations. At the basin level, the genetic distance between groups of individuals in different basins was positively correlated to the mean slope separating these basins. The probable origins and directions of individual movements (i.e. migration between clusters and basin colonization inside clusters) were inferred from assignment tests. This approach shows that steep and dry lands can stop, impede or divert the dispersal of a mobile carnivore such as the otter. [source] The Expansion of the Finance Industry and Its Impact on the Economy: A Territorial Approach Based on Swiss Pension FundsECONOMIC GEOGRAPHY, Issue 3 2009José Corpataux abstract A new economic geography of finance is emerging, and the current "financialization" of contemporary economies has contributed greatly to the reshaping of the economic landscape. How can these changes be understood and interpreted, especially from a territorial point of view? There are two contradictory economic theories regarding the tangible effects of the rise of the finance industry. According to neoclassical financial theorists, the finance industry's success is based on its positive effects on the real economy through its capacity to allocate financial resources efficiently. An alternative approach, adopted here, posits that finance does not merely mirror the real economy and that the financial economy, far from being a simple instrument for the allocation of capital, has its own autonomy, its own logic of development and expansion. A series of complex, and sometimes contradictory, connections link financial markets and the real economy, and there are some tensions between them, calling into question the coherence of the regional and national economies that follow from them. Moreover, the territorial approach shows how the mobility/liquidity of capital and the changing dimensions of new regions and countries are central to the finance industry's functioning. This article builds an understanding of the financial system through the lens of pension funds and highlights the impact of such a system on the real economy and its geography. [source] Diagnostic evaluation of conceptual rainfall,runoff models using temporal clusteringHYDROLOGICAL PROCESSES, Issue 20 2010N. J. de Vos Abstract Given the structural shortcomings of conceptual rainfall,runoff models and the common use of time-invariant model parameters, these parameters can be expected to represent broader aspects of the rainfall,runoff relationship than merely the static catchment characteristics that they are commonly supposed to quantify. In this article, we relax the common assumption of time-invariance of parameters, and instead seek signature information about the dynamics of model behaviour and performance. We do this by using a temporal clustering approach to identify periods of hydrological similarity, allowing the model parameters to vary over the clusters found in this manner, and calibrating these parameters simultaneously. The diagnostic information inferred from these calibration results, based on the patterns in the parameter sets of the various clusters, is used to enhance the model structure. This approach shows how diagnostic model evaluation can be used to combine information from the data and the functioning of the hydrological model in a useful manner. Copyright © 2010 John Wiley & Sons, Ltd. [source] MULTIPLE CRITERIA SCREENING OF A LARGE WATER POLICY SUBSET SELECTION PROBLEM,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2001Siamak Rajabi ABSTRACT: A new screening approach is applied to a large-scale multiple criteria water management problem to remove actions that cannot possibly be in the best subset. An inherent advantage of the approach is its ability to identify inferior actions by examining them individually, rather than within subsets. In a case study involving the selection of actions to address high water levels in the Great Lakes-St. Lawrence Basin, two statistical indicators, the mode and the mean, are used to aggregate the opinions of experts and representatives of interest groups on the impacts of actions according to various criteria. Application of the screening approach shows that some of the proposed actions can be removed as they can never be in the optimal subset, thereby reducing the size of the problem. [source] A halo model of galaxy colours and clustering in the Sloan Digital Sky SurveyMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2009Ramin A. Skibba ABSTRACT Successful halo-model descriptions of the luminosity dependence of clustering distinguish between the central galaxy in a halo and all the others (satellites). To include colours, we provide a prescription for how the colour,magnitude relation of centrals and satellites depends on halo mass. This follows from two assumptions: (i) the bimodality of the colour distribution at a fixed luminosity is independent of halo mass and (ii) the fraction of satellite galaxies which populate the red sequence increases with luminosity. We show that these two assumptions allow one to build a model of how galaxy clustering depends on colour without any additional free parameters than those required to model the luminosity dependence of galaxy clustering. We then show that the resulting model is in good agreement with the distribution and clustering of colours in the Sloan Digital Sky Survey, both by comparing the predicted correlation functions of red and blue galaxies with measurements and by comparing the predicted colour,mark correlation function with the measured one. Mark correlation functions are powerful tools for identifying and quantifying correlations between galaxy properties and their environments: our results indicate that the correlation between halo mass and environment is the primary driver for correlations between galaxy colours and the environment; additional correlations associated with halo ,assembly bias' are relatively small. Our approach shows explicitly how to construct mock catalogues which include both luminosities and colours , thus providing realistic training sets for, e.g., galaxy cluster-finding algorithms. Our prescription is the first step towards incorporating the entire spectral energy distribution into the halo model approach. [source] Clinical outcomes of corneal wavefront customized ablation strategies with SCHWIND CAM in LASIK treatmentsOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2009Maria Clara Arbelaez Abstract Purpose:, To evaluate the clinical outcomes of aspheric corneal wavefront (CW) ablation profiles in LASIK treatments. Methods:, Thirty eyes treated with CW ablation profiles were included after a follow-up of 6 months. In all cases, standard examinations including preoperative and postoperative wavefront analysis with a CW topographer (Optikon Keratron Scout) were performed. Custom Ablation Manager (CAM) software was used to plan corneal wavefront customized aspheric treatments, and the ESIRIS flying spot excimer laser system was used to perform the ablations (both SCHWIND eye-tech-solutions, Kleinhostheim, Germany). Clinical outcomes were evaluated in terms of predictability, refractive outcome, safety, and wavefront aberration. Results:, In general, the postoperative uncorrected visual acuity and the best corrected visual acuity improved (p < 0.001). In particular, the trefoil, coma, and spherical aberrations, as well as the total root-mean-square values of higher order aberrations, were significantly reduced (p < 0.05) when the pre-existing aberrations were greater than the repeatability and the biological noise. Conclusions:, The study results indicate that the aspheric corneal wavefront customized CAM approach for planning ablation volumes yields visual, optical, and refractive results comparable to those of other wavefront-guided customized techniques for correction of myopia and myopic astigmatism. The CW customized approach shows its strength in cases where abnormal optical systems are expected. Apart from the risk of additional ablation of corneal tissue, systematic wavefront-customized corneal ablation can be considered as a safe and beneficial method. [source] Eine Lanze für den Sachverständigenrat?PERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 4 2007Plädoyer für eine differenziertere Analyse wirtschaftswissenschaftlicher Beratungsinstitutionen On a closer look, these conclusions are disputable. Therefore, in this contribution we analyse both institutions with respect to different functions of scientific advice such as: (1) operative advice, (2) conception, (3) information of the public, (4) legitimization, and (5) filter. Our approach shows that the simultaneous treatment of all functions by one institution is impossible. Finally, the institutionalization of the German Council is quite appropriate with respect to some functions of scientific advice. [source] Strong spin relaxation length dependence on electric field gradientsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2006D. Csontos Abstract We discuss the influence of electrical effects on spin transport, and in particular the propagation and relaxation of spin polarized electrons in the presence of inhomogeneous electric fields. We show that the spin relaxation length strongly depends on electric field gradients, and that significant suppression of electron spin polarization can occur as a result thereof. A discussion in terms of a drift-diffusion picture, and selfconsistent numerical calculations based on a Boltzmann-Poisson approach shows that the spin relaxation length in fact can be of the order of the charge screening length. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Informed Consent: Documenting the Intersection of Bureaucratic Regulation and Ethnographic PracticePOLAR: POLITICAL AND LEGAL ANTHROPOLOGY REVIEW, Issue 2 2007Jennifer Shannon Standardized institutional review board (IRB) procedures suggest that informed consent can be enacted in the same way everywhere,across disciplines and across different cultural communities. With attention to documents as artifacts and embedding ethics, I consider consent documents to be located at a productive site for anthropological analysis the intersection of bureaucratic and ethnographic practice. Through fieldwork that engaged both American Indians in Chicago and museum professionals in Washington, D.C., I was able to view these procedures in a variety of contexts. Unlike the joking references to IRB scripts when interviewing museum professionals, American Indians were wary of such procedures. The particular meaning attached to signing documents varied in these communities and in one case prompted people to challenge and change the consent protocol that I would use in my fieldwork practice. This comparative approach shows how different institutions are represented by and transact through documents in ways that significantly impact the nature of fieldwork relations. [source] Cysteine-capped ZnSe quantum dots as affinity and accelerating probes for microwave enzymatic digestion of proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2009Lokesh A. Shastri Fluorescent semiconductor quantum dots (QDs) exhibit great potential and capability for many biological and biochemical applications. We report a simple strategy for the synthesis of aqueous stable ZnSe QDs by using cysteine as the capping agent (ZnSe-Cys QDs). The ZnSe QDs can act as affinity probes to enrich peptides and proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis. This nanoprobe could significantly enhance protein signals (insulin, ubiquitin, cytochrome c, myoglobin and lysozyme) in MALDI-TOFMS by 2.5,12 times compared with the traditional method. Additionally, the ZnSe-Cys QDs can be applied as heat absorbers (as accelerating probes) to speed up microwave-assisted enzymatic digestion reactions and also as affinity probes to enrich lysozyme-digested products in MALDI-TOFMS. Furthermore, after the enrichment experiments, the solutions of ZnSe-Cys QDs mixed with proteins can be directly deposited onto the MALDI plates for rapid analysis. This approach shows a simple, rapid, efficient and straightforward method for direct analysis of proteins or peptides by MALDI-TOFMS without the requirement for further time-consuming separation processes, tedious washing steps or laborious purification procedures. The present study has demonstrated that ZnSe-Cys QDs are reliable and potential materials for rapid, selective separation and enrichment of proteins as well as accelerating probes for microwave-digested reactions for proteins than the regular MALDI-MS tools. Additionally, we also believe that this work may also inspire investigations for applications of QDs in the field of MALDI-MS for proteomics. Copyright © 2009 John Wiley & Sons, Ltd. [source] Source selectivity: An assessment of volcanic glass sources in the southern primorye region, far East RussiaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2008Trudy Doelman Artifacts made from volcanic glass have been found in archaeological contexts dating from the Late Palaeolithic (ca. 20,000 yr B.P.) through to the end of the Bronze Age (ca. 2700 yr B.P.) in the southern Primorye region of Far East Russia. A geoarchaeological survey of volcanic glass outcrops assessed the various potential sources to determine their potential for sustained exploitation. A characterization study of source samples and artifacts from 27 spatially and temporally dispersed sites using a combination of PIXE-PIGME and relative density identified which sources had actually been exploited and a technological analysis of the assemblages described patterns of use. The combination of these three approaches shows the impact of a relatively stable geological environment on patterns of procurement and exchange. © 2008 Wiley Periodicals, Inc. [source] Reactive transport parameter estimation: Genetic algorithm vs.AICHE JOURNAL, Issue 8 2009Monte carlo approach Abstract This article concerns reactive transport in porous media with an emphasis on the optimization of the chemical parameters. The transport of Cadmium (Cd) and tributyltin (TBT) in column experiments were used as test cases. The reactive transport model is described by a set of chemical reactions with equilibrium constants as the main adjustable parameters. As such a problem is highly nonlinear and can have multiple minima, global parameter estimation methods are more suitable than local gradient-based methods. This article focuses on the application of a genetic algorithm (GA) in estimating chemical equilibrium parameters of a reactive transport model. The GA is capable of minimizing the difference between the measured and modeled breakthrough curves for both Cd and TBT. A comparison between GA and Monte-Carlo approaches shows that the GA performance is better than the Monte-Carlo, especially for a small number of evaluations of the cost function. The results of this study show that the use of GA to estimate the parameters of reactive transport models is promising. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] | |||||||||||||||||||