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Terms modified by Very Different Selected AbstractsBenchmarking message-oriented middleware: TIB/RV versus SonicMQCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 12 2005Piyush Maheshwari Abstract Message-oriented middleware (MOM) has become a vital part of the complex application integration projects. MOM is used to pass data and workflow in the form of messages between different enterprise applications. The performance of integrated applications greatly depends on how effectively the MOM performs. This paper presents a benchmark comparison between two industry well-known MOMs,TIBCO Rendezvous (TIB/RV) and SonicMQ. Although the two MOMs are very similar in certain respects, their native implementation and architecture are very different. We provide an unbiased benchmark reference to the middleware selection process. The primary objective of our work is to evaluate and compare the MOMs by testing their effectiveness in the delivery of messages in publish/subscribe and point-to-point message domains, their program stability and the system resource utilization. Copyright © 2005 John Wiley & Sons, Ltd. [source] Characterization of the in vitro adherence behavior of ultrasound responsive double-shelled microspheres targeted to cellular adhesion moleculesCONTRAST MEDIA & MOLECULAR IMAGING, Issue 6 2006Susanne Ottoboni Abstract We have developed novel adhesion molecule-targeted double-shelled microspheres which encapsulate nitrogen. We report in vitro targeting studies utilizing these microspheres conjugated to target-specific antibodies directed towards ICAM-1 and VCAM-1. In static adherence experiments, the adherence patterns of microspheres conjugated to three different monoclonal antibodies (two targeted to ICAM-1 and one to VCAM-1) to their target surfaces were very different. Maximum microsphere adherence at the lowest target and/or ligand densities was observed with the VCAM-1 system. Differences in target-specific adherence were also observed between anti-ICAM-1 and anti-VCAM-1 microsphere conjugates in flow adherence studies. Equilibrium binding studies of the target proteins in solution to the microsphere-bound ligands showed that the affinity constants of two microsphere-bound monoclonal antibodies for their target proteins are similar. Thus, ligand,target affinity is not the only determinant of microsphere adherence to the target surface in our systems. Shear stress was found to have an effect on the mean diameter of adhered microspheres; a decrease in the mean diameter with increasing shear was observed. The magnitude of this effect was dependent on both microsphere-bound ligand and target surface densities, with a more pronounced change at lower densities. Adhered microspheres were readily detectable using ultrasound at the lowest tested surface density of 40,mm,2. Copyright © 2006 John Wiley & Sons, Ltd. [source] Reverse Auctions with Multiple Reinforcement Learning Agents,DECISION SCIENCES, Issue 1 2008Subhajyoti Bandyopadhyay ABSTRACT Reverse auctions in business-to-business (B2B) exchanges provide numerous benefits to participants. Arguably the most notable benefit is that of lowered prices driven by increased competition in such auctions. The competition between sellers in reverse auctions has been analyzed using a game-theoretic framework and equilibria have been established for several scenarios. One finding of note is that, in a setting in which sellers can meet total demand with the highest-bidding seller being able to sell only a fraction of the total capacity, the sellers resort to a mixed-strategy equilibrium. Although price randomization in industrial bidding is an accepted norm, one might argue that in reality managers do not utilize advanced game theory calculations in placing bids. More likely, managers adopt simple learning strategies. In this situation, it remains an open question as to whether the bid prices converge to the theoretical equilibrium over time. To address this question, we model reverse-auction bidding behavior by artificial agents as both two-player and n -player games in a simulation environment. The agents begin the game with a minimal understanding of the environment but over time analyze wins and losses for use in determining future bids. To test for convergence, the agents explore the price space and exploit prices where profits are higher, given varying cost and capacity scenarios. In the two-player case, the agents do indeed converge toward the theoretical equilibrium. The n -player case provides results that reinforce our understanding of the theoretical equilibria. These results are promising enough to further consider the use of artificial learning mechanisms in reverse auctions and other electronic market transactions, especially as more sophisticated mechanisms are developed to tackle real-life complexities. We also develop the analytical results when one agent does not behave strategically while the other agent does and show that our simulations for this environment also result in convergence toward the theoretical equilibrium. Because the nature of the best response in the new setting is very different (pure strategy as opposed to mixed), it indicates the robustness of the devised algorithm. The use of artificial agents can also overcome the limitations in rationality demonstrated by human managers. The results thus have interesting implications for designing artificial agents in automating bid responses for large numbers of bids where human intervention might not always be possible. [source] Meet the New Hybrid DesignersDESIGN MANAGEMENT REVIEW, Issue 2 2010Michael Eckersley Many of them have changed careers, or the focus of their careers, and have arrived at graduate design programs from a background very different from that of traditional designers. They're likely to add a different flavor to the design mix,and bring a considerable amount of business acumen, as well. [source] Temperature perception and nociceptionDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2004Barry G. Green Abstract The specificity theory of somesthesis holds that perceptions of warmth, cold, and pain are served by separate senses. Although no longer accepted in all its details, the theory's basic assumptions of anatomical and functional specificity have remained guiding principles in research on temperature perception and its relationship to pain. This article reviews the response characteristics of thermoreceptors, temperature-sensitive nociceptors, and their associated pathways in the context of old and new perceptual phenomena, most of which cannot be satisfactorily explained by the specificity theory. The evidence indicates that throughout most of the perceptual range, temperature sensitivity depends upon coactivation of, and interactions among, thermal and nociceptive pathways that are composed of both specific "labeled lines" and nonspecific, multimodal fibers. Adding to this complexity is evidence that tactile stimulation can influence the way in which thermal stimulation is perceived. It is argued that thermoreception is best defined as a functional subsystem of somesthesis that serves the very different and sometimes conflicting demands of thermoregulation, protection from thermal injury, and haptic perception. © 2004 Wiley Periodicals, Inc. J Neurobiol 61: 13,29, 2004 [source] The Role of Research Institutions in Seed,related Disaster Relief: Seeds of Hope Experiences in RwandaDISASTERS, Issue 4 2002Robin A. Buruchara The article describes the efforts of a coalition of agricultural research centres, Seeds of Hope (SOH) in the rebuilding of Rwanda, after the genocide and war of 1994. Research involvement in emergency relief and rehabilitation was unusual at the time and SOH had to forge its unique complementary role. Focusing on crop and variety development and conservation it: provided technical advice to relief agencies on seed procurement; used its baseline ken to assess the effects of war on seed diversity and seed security; made preparations to restore specific germplasm (which, fortunately, proved unnecessary) and spent substantial effort on rebuilding human resource capacity in research as well as basic scientific facilities. The involvement of SOH highlighted the critical, yet very different, roles for research during emergency versus rehabilitation periods and demonstrated the cost effectiveness of building in a diagnostic component , before massive seed or germplasm distributions are programmed. [source] Probabilistic estimate of seismic response design values of RC framesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 15 2009Angelo D'Ambrisi Abstract Probabilistically controlled design values of the nonlinear seismic response of reinforced concrete frames are obtained using a method previously proposed by the authors. The method allows to calculate conservative design values characterized by a predefined non-exceedance probability, using a limited number of spectrum-fitting generated accelerograms. Herein the method is applied to elastic-strain hardening single degree of freedom systems representative of RC framed structures and is then assessed with reference to four reinforced concrete model frames designed according to EC8. The frames are characterized by different natural periods and aspect ratios. The results, compared with those obtained applying current EC8 recommendations, show the effectiveness of the proposed method. EC8 provides for design values of the seismic response of a structure with a nonlinear behavior computed as the mean value of the responses to seven accelerograms or as the maximum value of the responses to three accelerograms. These two criteria lead to design values characterized by very different and uncontrolled non-exceedance probability levels, while the proposed method allows the analyst to directly control the non-exceedance probability level of the calculated design values. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dimensional analysis of the earthquake-induced pounding between adjacent structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 7 2009Elias Dimitrakopoulos Abstract In this paper the dynamic response of two and three pounding oscillators subjected to pulse-type excitations is revisited with dimensional analysis. Using Buckingham's ,-theorem the number of variables that govern the response of the system is reduced by three. When the response is presented in the dimensionless ,-terms remarkable order emerges. It is shown that regardless of the acceleration level and duration of the pulse all response spectra become self-similar and follow a single master curve. This is true despite the realization of finite duration contacts with increasing durations as the excitation level increases. All physically realizable contacts (impacts, continuous contacts, and detachments) are captured via a linear complementarity approach. The study confirms the existence of three spectral regions. The response of the most flexible among the two oscillators amplifies in the low range of the frequency spectrum (flexible structures); whereas, the response of the most stiff among the two oscillators amplifies at the upper range of the frequency spectrum (stiff structures). Most importantly, the study shows that pounding structures such as colliding buildings or interacting bridge segments may be most vulnerable for excitations with frequencies very different from their natural eigenfrequencies. Finally, by applying the concept of intermediate asymptotics, the study unveils that the dimensionless response of two pounding oscillators follows a scaling law with respect to the mass ratio, or in mathematical terms, that the response exhibits an incomplete self-similarity or self-similarity of the second kind with respect to the mass ratio. Copyright © 2008 John Wiley & Sons, Ltd. [source] Influence of dynamic soil,structure interaction on the nonlinear response and seismic reliability of multistorey systemsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2007Armando Bárcena Abstract A set of reinforced concrete structures with gravitational loads and mechanical properties (strength and stiffness) representative of systems designed for earthquake resistance in accordance with current criteria and methods is selected to study the influence of dynamic soil,structure interaction on seismic response, ductility demands and reliability levels. The buildings are considered located at soft soil sites in the Valley of Mexico and subjected to ground motion time histories simulated in accordance with characteristic parameters of the maximum probable earthquake likely to occur during the system's expected life. For the near-resonance condition the effects of soil,structure interaction on the ductility demands depend mainly on radiation damping. According to the geometry of the structures studied this damping is strongly correlated with the aspect ratio, obtained by dividing the building height by its width. In this way, for structures with aspect ratio greater than 1.4 the storey and global ductility demands increase with respect to those obtained with the same structures but on rigid base, while for structures with aspect ratio less than 1.4 the ductility demands decrease with respect to those for the structures on rigid base. For the cases when the fundamental period of the structure has values very different from the dominant ground period, soil,structure interaction leads in all cases to a reduction of the ductility demands, independently of the aspect ratio. The reliability index , is obtained as a function of the base shear ratio and of the seismic intensity acting on the nonlinear systems subjected to the simulated motions. The resulting reliability functions are very similar for systems on rigid or on flexible foundation, provided that in the latter case the base rotation and the lateral displacement are removed from the total response of the system. Copyright © 2006 John Wiley & Sons, Ltd. [source] Specialization across varieties and North,South competitionECONOMIC POLICY, Issue 53 2008Lionel Fontagné SUMMARY North,South competition quality Analyzing a new database that makes it possible to disaggregate trade flows across many countries according to unit values, we show that international specialization in terms of quality within industries and product categories plays an important role in the dynamics of North,South competition. The different specialization of countries at different levels of development within products and across varieties is mirrored in the recent shifts in world market shares, which are very different across quality segments: the South is not gaining market share in high-value portions of trade pattern. In this respect Europe's specialization pattern appears to be different from that of the US and Japan, and may allow it to better resist the competitive pressure of the South. , Lionel Fontagné, Guillaume Gaulier and Soledad Zignago [source] Marketization of household production and the EU,US gap in workECONOMIC POLICY, Issue 41 2005Richard B. Freeman SUMMARY Jobs and homework Time-use evidence Employment rates and hours worked per employee are very different in the EU and the US. This paper relates the greater time worked in the US to greater marketization in the US of traditional household production: food preparation, childcare, elderly care, cleaning houses. Since women do most household work, marketization is particularly relevant to the EU,US difference in hours worked by women. We suggest that to raise employment rates the EU should develop policies that make it easier for women to move from the household to the market and to substitute market goods and services for household production. , Richard B. Freeman and Ronald Schettkat [source] DEWEYAN DARWINISM FOR THE TWENTY-FIRST CENTURY: TOWARD AN EDUCATIONAL METHOD FOR CRITICAL DEMOCRATIC ENGAGEMENT IN THE ERA OF THE INSTITUTE OF EDUCATION SCIENCESEDUCATIONAL THEORY, Issue 3 2008Deborah Seltzer-Kelly Early in the twentieth century, John Dewey also advocated for a vision of education guided by science, and more recent scholarship has validated many of his ideas. However, as Deborah Seltzer-Kelly argues in this essay, Dewey's vision of a scientifically based system of education was very different from that envisioned by the IES, and also very different from that implied by the progenitor of contemporary evolutionary thought, Donald Campbell. Seltzer-Kelly proposes a Deweyan Darwinist model of educational method as a genuinely scientific alternative to the scientism that pervades current official efforts to imbue education with science. The implications of this model are profound, highlighting the difference between education as preparation for consent to authoritarian structures and education as preparation for genuinely democratic participation. [source] Separation of propranolol enantiomers by CE using sulfated ,-CD derivatives in aqueous and non-aqueous electrolytes: Comparative CE and NMR study,ELECTROPHORESIS, Issue 9 2010Anne-Catherine Servais Abstract Separations using CE employing non-aqueous BGE are already as well established as separations in aqueous buffers. The separation mechanisms in achiral CE with non-aqueous BGEs are most likely similar to those in aqueous buffers. However, for the separation of enantiomers involving their interaction with chiral buffer additives, the interaction mechanisms might be very different in aqueous and non-aqueous BGEs. While the hypothesis regarding distinct mechanisms of enantiomer separations in aqueous and non-aqueous BGEs has been mentioned in several papers, no direct proof of this hypothesis has been reported to date. In the present study, the enantiomers of propranolol were resolved using CE in aqueous and non-aqueous methanolic BGEs with two single isomer sulfated derivatives of ,-CD, namely heptakis (2,3-diacetyl-6-sulfo)-,-CD and heptakis (2,3-dimethyl-6-sulfo)-,-CD. The enantiomer migration order of propranolol was inverted when an aqueous BGE was replaced with non-aqueous BGE in the case of heptakis (2,3-dimethyl-6-sulfo)-,-CD but remained the same in the case of heptakis (2,3-diacetyl-6-sulfo)-,-CD. The possible molecular mechanisms leading to this reversal of enantiomer migration order were studied by using nuclear overhauser effect spectroscopy in both aqueous and non-aqueous BGEs. [source] Marine diatom species harbour distinct bacterial communitiesENVIRONMENTAL MICROBIOLOGY, Issue 6 2005Hans-Peter Grossart Summary We examined bacterial dynamics in batch cultures of two axenic marine diatoms (Thalassiosira rotula and Skeletonema costatum). The axenic diatoms were inoculated with natural bacterial assemblages and monitored by 4,6-diamidino-2-phenolindole (DAPI) counts, denaturing gradient gel electrophoresis (DGGE) with subsequent analysis of excised, sequenced 16S rRNA gene fragments, and fluorescence in situ hybridization (FISH) with group-specific 16S rRNA oligonucleotide probes. Our results show that algal growth exhibited pronounced differences in axenic treatments and when bacteria were present. Bacterial abundance and community structure greatly depended on species, growth and physiological status of even closely related algae. Free-living and phytoplankton-associated bacteria were very different from each other and were dominated by distinct phylogenetic groups. The diatom-associated bacteria mainly belonged to the Flavobacteria,Sphingobacteria group of the Bacteroidetes phylum whereas free-living bacteria, which were rather similar in both cultures, comprised mainly of members of the Roseobacter,group ,of ,,- Proteobacteria. ,Presence and disappearance of specific bacteria during algal growth indicated pronounced differences in environmental conditions over time and selection of bacteria highly adapted to the changing conditions. Tight interactions between marine bacteria and diatoms appear to be important for the decomposition of organic matter and nutrient cycling in the sea. [source] Influence of isolation on the recovery of pond mesocosms from the application of an insecticide.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2007Abstract The immediate response and recovery of the macrobenthic communities of nonisolated and isolated freshwater outdoor 9 m3 mesocosms following an acute stress caused by the addition of deltamethrin were studied over a 14-month period. To discriminate between internal and external recovery mechanisms, half of the treated ponds were covered by 1-mm mesh lids that restricted aerial recolonization. Both structural (abundance of the different taxonomic groups) and functional (litter breakdown) parameters were monitored. Insects were broadly reduced in numbers by deltamethrin addition. In general, noninsect groups were not affected or increased in abundance in deltamethrin-treated ponds, probably because of relative insensitivity to deltamethrin, reduced predation, and lower competition for food. No major change in litter breakdown rates were seen, probably because of functional redundancy among the macrobenthic community. Chironominae larvae recovered in open, treated mesocosms 62 d after deltamethrin addition and most insect groups recovered 84 d after the treatment date. However, the presence of lids significantly reduced insect recovery rate, suggesting that it largely depends on the immigration of winged forms (i.e., external recovery) from surrounding non- or less affected systems. These results indicate that the recovery time of macrobenthic communities in an affected natural pond would depend on spatial characteristics of the landscape and also the season that exposure occurs. Isolated ecosystems would display posttreatment insect recovery dynamics very different from highly connected ones, evolving toward alternate pseudoequilibrium states, possibly with lower biodiversity but with preserved functionality. Consequences for higher tier risk assessment of pesticides are discussed. [source] Assessing sediment contamination in estuariesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2001Peter M. Chapman Abstract Historic and ongoing sediment contamination adversely affects estuaries, among the most productive marine ecosystems in the world. However, all estuaries are not the same, and estuarine sediments cannot be treated as either fresh or marine sediments or properly assessed without understanding both seasonal and spatial estuarine variability and processes, which are reviewed. Estuaries are physicochemically unique, primarily because of their variable salinity but also because of their strong gradients in other parameters, such as temperature, pH, dissolved oxygen, redox potential, and amount and composition of particles. Salinity (overlying and interstitial) varies spatially (laterally, vertically) and temporally and is the controlling factor for partitioning of contaminants between sediments and overlying or interstitial water. Salinity also controls the distribution and types of estuarine biota. Benthic infauna are affected by interstitial salinities that can be very different than overlying salinities, resulting in large-scale seasonal species shifts in salt wedge estuaries. There are fewer estuarine species than fresh or marine species (the paradox of brackish water). Chemical, toxicological, and community-level assessment techniques for estuarine sediment are reviewed and assessed, including chemistry (grain size effects, background enrichment, bioavailability, sediment quality values, interstitial water chemistry), biological surveys, and whole sediment toxicity testing (single-species tests, potential confounding factors, community level tests, laboratory-to-field comparisons). Based on this review, there is a clear need to tailor such assessment techniques specifically for estuarine environments. For instance, bioavailability models including equilibrium partitioning may have little applicability to estuarine sediments, appropriate reference comparisons are difficult in biological surveys, and there are too few full-gradient estuarine sediment toxicity tests available. Specific recommendations are made to address these and other issues. [source] An evidence-based approach to equine parasite control: It ain't the 60s anymoreEQUINE VETERINARY EDUCATION, Issue 6 2010R. M. Kaplan Summary Most veterinarians continue to recommend anthelmintic treatment programmes for horses that derive from knowledge and concepts more than 40 years old. However, much has changed since these recommendations were first introduced and current approaches routinely fail to provide optimal or even adequate levels of parasite control. There are many reasons for this. Recent studies demonstrate that anthelmintic resistance in equine parasites is highly prevalent and multiple-drug resistance is common in some countries, but few veterinarians take this into account when making treatment decisions or when recommending rotation of anthelmintics. Furthermore, the current approach of treating all horses at frequent intervals was designed specifically to control the highly pathogenic large strongyle, Strongylus vulgaris. But this parasite is now quite uncommon in managed horses in most of the world. Presently, the cyathostomins (small strongyles) are the principal parasitic pathogens of mature horses. The biology and pathogenesis of cyathostomins and S. vulgaris are very different and therefore require an entirely different approach. Furthermore, it is known that parasites are highly over-dispersed in hosts, such that a small percentage of hosts harbour most of the parasites. The common practices of recommending the same treatment programme for all horses despite great differences in parasite burdens, recommending prophylactic treatment of all horses without indication of parasitic disease or knowing what species of parasites are infecting the horses, recommending use of drugs without knowledge of their efficacy and failing to perform diagnostic (faecal egg count) surveillance for estimating parasite burdens and determining treatment efficacy, are all incompatible with current standards of veterinary practice. Consequently, it is necessary that attitudes and approaches to parasite control in horses undergo a complete overhaul. This is best achieved by following an evidence-based approach that takes into account all of these issues and is based on science, not tradition. [source] Our Common European Model of AgricultureEUROCHOICES, Issue 3 2006Juha Korkeaoja Our Common European Model of Agriculture Future internal and external forces on European agriculture mean that the CAP may look very different after 2013. However large these changes, the CAP will need to retain its common principles based on the European Model of Agriculture (EMA). This became clear in an informal September meeting of EU agriculture ministers in Oulu, arranged by the Finnish Presidency. A strong CAP will be needed in the future but it will have to evolve to meet upcoming challenges. Work on the future CAP will need to start soon and the Oulu meeting may become known as the starting point for those discussions. The CAP will have to provide a reasonable environment for practicing agriculture for very different farmers in very diverse conditions, and facilitate the supply of a wide variety of goods and services to consumers and taxpayers as only truly multifunctional agriculture can. If the CAP can maintain these characteristics it has an important role to play in a future Europe. The meeting in Oulu was also an important milestone for a very special reason: for the first time, all ten New Member States took an active part in the EMA-debate with full rights and responsibilities as part of the Union. Once again this underlines the central role of our common European Model of Agriculture. Unser gemeinsames Europäisches Land wirts chafts modell Die zukünftigen internen und externen Einflüsse auf die europäische Landwirtschaft könnten zur Folge haben, dass die GAP nach dem Jahr 2013 ganz anders aussieht. Wie umwälzend diese Veränderungen auch sein mögen, die GAP wird ihre allgemeinen, auf dem Europäischen Landwirtschaftsmodell (EMA) beruhenden Grundsätze beibehalten müssen. Dies wurde im September bei einem von der finnischen Präsidentschaft arrangierten informellen Treffen der EU-Landwirtschaftsminister in Oulu deutlich. In der Zukunft brauchen wir eine starke GAP, die jedoch weiterentwickelt werden muss, um den kommenden Herausforderungen gerecht zu werden. Die Arbeit an der zukünftigen GAP muss in nächster Zeit beginnen, und das Treffen in Oulu könnte möglicherweise als Ausgangspunkt dieser Diskussionen gelten. Die GAP wird ein angemessenes Umfeld schaffen müssen, um sehr unterschiedlichen Landwirten mit sehr unterschiedlichen Arbeitsbedingungen die Ausübung der Landwirtschaft sowie Verbrauchern und Steuerzahlern die Versorgung mit einer großen Vielfalt an Waren und Dienstleistungen zu ermöglichen, wie es nur eine wirklich multifunktionale Landwirtschaft zu leisten vermag. Wenn es der GAP gelingt, diese Merkmale beizubehalten, wird ihr im zukünftigen Europa eine wichtige Rolle zukommen. Bei dem Treffen in Oulu handelt es sich auch aus einem ganz besonderen Grund um einen bedeutenden Meilenstein: Zum ersten Mal beteiligte sich jeder der zehn neuen Mitgliedsstaaten mit allen Rechten und voller Verantwortung als Teil der Union aktiv an der Debatte zum Europäischen Landwirtschaftsmodell. Wieder einmal unterstreicht dies die zentrale Rolle unseres gemeinsamen Europäischen Landwirtschaftsmodells. Ce modèle agricole européen qui nous est commun Du fait des forces internes et externes qui vont bientôt s'exercer sur l'agriculture européenne, la physionomie de la PAC après 2013 pourrait bien être très différente de ce qu'elle est maintenant. Quelque soit cependant l'importance de ces changements, la PAC devra conserver sa base commune actuelle, qui repose sur le « modèle agricole européen » (MAE). La chose est apparue clairement lors d'une réunion informelle des ministres de l'agriculture européens organisée par la présidence finnoise à Oulu, en septembre dernier. Une politique agricole musclée sera nécessaire à l'avenir, mais elle devra évoluer pour répondre à de nouveaux défis. Il va bientôt falloir commencer à travailler cette nouvelle PAC, et la réunion d'Oulu restera peut être comme le point de départ des discussions sur le sujet. La PAC devra fournir un environnement convenable pour la pratique d'agricultures diverses, par des agriculteurs différents les uns des autres, dans un vaste éventail de conditions. Elle devra permettre la production d'une grande variété de biens et de services financés par le consommateur ou le contribuable, comme seule une agriculture multifonctionnelle peut le faire. Si la PAC arrive à conserver ces caractéristiques, elle aura un grand rôle à jouer dans l'Europe de demain. Il y a encore une raison plus spécifique pour marquer d'une pierre blanche la réunion d'Oulu : pour la première fois, les dix nouveaux membres de l'Union ont activement participé et de plein droit aux discussions sur le MAE. Cela, une fois de plus, souligne le rôle essentiel du « modèle agricole européen » qui nous est commun. [source] Europe and the Crisis in Scientific VocationsEUROPEAN JOURNAL OF EDUCATION, Issue 4 2005BERNARD CONVERT During the 1990s, the number of students enrolling in science subjects at universities was declining each year in Germany, France, Italy, amongst other countries. These decreases are too readily attributed to a general disaffection caused by the image that younger generations have of scientific studies: they are seen as being the most ,difficult'. This explanation is true but not sufficient. Over and above the similarities that can be seen between European countries , which stem from the fact that they are simultaneously experiencing strong growth in and democratisation of their student populations ,, profound differences continue to exist, resulting in apparently similar effects, but with very different causes. Not only do higher education structures taken as a whole remain very different despite the Bologna process, but more fundamentally, the very meaning of the higher education system within each national society, its relationship with employment, and its position in individuals' personal career paths all vary. A comparison between Germany, Italy and France shows three ideal types of relationship between training and employment and three ways of explaining symptoms that appear similar. [source] Structure Variation and Luminescence Properties of Lanthanide Complexes Incorporating a Naphthalene-Derived Chromophore Featuring Salicylamide Pendant ArmsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2008Xue-Qin Song Abstract A new potentially bridging ligand containing two salicylamide pendant arms separated by a 2,3-dimethoxynaphthalene spacer has been prepared and its coordination chemistry with LnIII ions has been investigated. An analysis of the presented crystal structures indicates that the diversity of these supramolecular structures is mainly dictated by the nature of the metal ions. These compounds represent good examples of tuning crystal structures arising from the flexibility of the ligands and the Ln contraction effect. Luminescence studies showed that the introduction of the methoxyl substituents on the naphthalene backbone lowers the triplet energy and considerably changes the luminescent behaviors of the EuIII and TbIII complexes, which is very different from the literature data on similar compounds. In the emission spectra of the Tb complex the ligand fluorescence remains relatively important because of the back-energy transfer from the TbIII ion to the ligand, which to the best of our knowledge, may be the first example of salicylamide lanthanide complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Variability of the masticatory process during chewing of elastic model foodsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2000Claire Lassauzay Many studies show a consistent individual chewing pattern; chewing being governed by a pattern generator and regulated by sensory feedback. The aim of this study was to determine the variation in chewing between sessions, replicates and subjects using elastic model foods. Fifteen young male subjects were selected to chew four food products differing in hardness. Four sessions were performed at 1-wk intervals for each subject and, within each session, the four model foods were presented 3 times each. Jaw movement was recorded simultaneously with masseter and anterior temporalis electromyographic activities. Several chewing characteristics increased progressively from one session to the next; the largest increase occurred from the 1st to the 2nd session, with little difference between the last two sessions. No differences were observed between the samples of the same food product within a session. As mastication progressed, the amplitude and speed of the cycles and the muscular work decreased progressively. The first cycle appeared to be very different from the subsequent for all parameters except for occlusal duration. Thus, under our experimental conditions, the origin and amount of variation in chewing patterns were identified and provide information to improve the accuracy and comparability of results in studies of mastication. [source] The Extraordinary Cocatalytic Action of Polymethylaluminoxane (MAO) in the Polymerization of Terminal Olefins by Metallocenes: Chemical Change in the Group 4 Metallocene Dimethyl Derivatives Induced by MAO,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2005John J. Eisch Abstract In the polymerization of olefins with Group 4 metallocene dichlorides or dimethyl derivatives as procatalysts the use of polymethylaluminoxane (MAO) as the cocatalyst, especially in extreme excess (102,103 times the metallocene equivalent), has been shown to have an extraordinary accelerating effect on the rate of olefin polymerization, when compared with the cocatalytic action of alkylaluminum halides. In attempts at explaining the greatly superior catalytic activity of MAO in olefin polymerization (the MAO conundrum), hypotheses have generally paralleled the steps involved in the cocatalytic action of RnAlCl3,n, namely the alkylation of Cp2MtCl2, ionization of Cp2Mt(R)Cl into the metallocenium cation, [Cp2Mt,R]+, and anion, [Rn,1AlCl4,n], and subsequent ion-pair separation. In order to understand any differences in catalytic action between such cocatalysts, we have studied the individual action of MAO (100 equiv.) and of MeAlCl2 (1,2 equiv.) on each of the Group 4 metallocene derivatives, Cp2TiCl2, Cp2ZrCl2, Cp2Ti(CH3)2 and Cp2Zr(CH3)2. With MeAlCl2 each of the metallocene derivatives appeared to form the cation, [Cp2Mt,CH3]+, with greater (Ti) or lesser (Zr) ease, because an alkyne such as diphenylacetylene was then found to insert into the Mt,CH3 bond stereoselectively. In striking contrast, treatment of each metallocene with MAO gave two reactions very different from MeAlCl2, namely a steady evolution of methane gas upon mixing and a finding upon hydrolytic workup that the diphenylacetylene present had undergone no insertion into the Mt,CH3 bond but instead had been reductively dimerized completely to (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene. To account for this astonishing difference in chemical behavior between MAO and MeAlCl2 in their cocatalytic activation of Group 4 metallocenes to olefin polymerization, it is necessary to postulate a novel, unique sequence of reaction steps occurring between MAO and the metallocene. If one starts with the metallocene dichloride, then the free TMA present in the MAO would generate the Cp2Mt(CH3)2. This metallocene dimethyl derivative, complexed with an oligomeric MAO unit, would undergo a transfer-epimetallation with added olefin or acetylene to form a metallacyclopropane or metallacyclopropene, respectively. With added diphenylacetylene the resulting 2,3-diphenylmetallacyclopropene would be expected rapidly to insert a second alkyne to form the 2,3,4,5-tetraphenyl-1-metallacyclopentadiene. Simple hydrolysis of the latter intermediate would generate (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene while alternative workup with D2O would give the 1,4-dideuterio derivative of this butadiene. Both such expectations were confirmed by experiment. In the case of added olefin, similar metallacyclopropane and metallacyclopentane intermediates should be produced until ring opening of the latter five-membered ring leads to an open-chain zwitterion, a process having ample precedent in the research of Gerhard Erker. The solution to the MAO conundrum then, namely the extraordinary cocatalytic activity of MAO in olefin polymerization by metallocenes, lies in the unique catalytic activation of the Group 4 metallocene dimethyl derivative, which occurs by transfer-epimetallation of the olefin monomer by the Cp2Mt(CH3)2,MAO complex. The most advantageous Lewis acidic sites in the MAO,oligomeric mixture for such metallocene,MAO complexation are suggested to be terminal Me2Al,O,AlMe, segments of an open-chain oligomer. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Factors controlling aggregation in a minimum and a conventionally tilled undulating fieldEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2007S. De Gryze Summary Wind and water erosion induce breakdown of soil aggregates and loss of soil organic matter. Whereas most of the relations between aggregation and its driving factors have been established on a plot scale, these relations might be very different within an undulating landscape where both erosion (by wind or water) and deposition occur. The aim of this study was to investigate to what degree spatial patterns in soil variables influence spatial patterns in aggregation under different tillage intensities. We studied an agricultural field of about 3 ha in the silty region of Belgium. The site was split into a conventional tillage (CT) and a minimum tillage (MT) system. Within the field, 396 geo-referenced surface soil samples (0,5 cm) were taken and analyzed for organic matter content, quantity of aggregates and a number of other soil properties. Under CT, 28.5% of the total sample variation was explained by the occurrence of depositional areas, 20.8% by the amount of soil organic matter, and 13.8% by the presence of a clay-rich B horizon which surfaced due to progressive water and tillage erosion. Regression analysis revealed that 27% of the variation in the quantity of macroaggregates (>0.25 mm) was accounted for by these three factors. Under MT, 27.1% of the total sample variation was related to the surface cover of Tertiary sand, 22.6% to the amount of soil organic matter, and 13% to erodibility. These three factors explained 53% of the variation in the quantity of macroaggregates. In the CT system, the correlation between grass- or maize- carbon and the quantity of macroaggregates was strongly linked to erodibility, while this was not the case in the MT system. We concluded that at this site, macroaggregation is dominated by landscape-scale processes (such as water or tillage erosion) rather than determined by the commonly considered local variables (such as small variations in texture or organic matter content). [source] ADAPTIVE CONSTRAINTS AND THE PHYLOGENETIC COMPARATIVE METHOD: A COMPUTER SIMULATION TESTEVOLUTION, Issue 1 2002Emilia P. Martins Abstract Recently, the utility of modern phylogenetic comparative methods (PCMs) has been questioned because of the seemingly restrictive assumptions required by these methods. Although most comparative analyses involve traits thought to be undergoing natural or sexual selection, most PCMs require an assumption that the traits be evolving by less directed random processes, such as Brownian motion (BM). In this study, we use computer simulation to generate data under more realistic evolutionary scenarios and consider the statistical abilities of a variety of PCMs to estimate correlation coefficients from these data. We found that correlations estimated without taking phylogeny into account were often quite poor and never substantially better than those produced by the other tested methods. In contrast, most PCMs performed quite well even when their assumptions were violated. Felsenstein's independent contrasts (FIC) method gave the best performance in many cases, even when weak constraints had been acting throughout phenotypic evolution. When strong constraints acted in opposition to variance-generating (i.e., BM) forces, however, FIC correlation coefficients were biased in the direction of those BM forces. In most cases, all other PCMs tested (phylogenetic generalized least squares, phylogenetic mixed model, spatial autoregression, and phylogenetic eigenvector regression) yielded good statistical performance, regardless of the details of the evolutionary model used to generate the data. Actual parameter estimates given by different PCMs for each dataset, however, were occasionally very different from one another, suggesting that the choice among them should depend on the types of traits and evolutionary processes being considered. [source] The origin of the endothelial cells: an evo-devo approach for the invertebrate/vertebrate transition of the circulatory systemEVOLUTION AND DEVELOPMENT, Issue 4 2005R. Muñoz-Chápuli Summary Circulatory systems of vertebrate and invertebrate metazoans are very different. Large vessels of invertebrates are constituted of spaces and lacunae located between the basement membranes of endodermal and mesodermal epithelia, and they lack an endothelial lining. Myoepithelial differentation of the coelomic cells covering hemal spaces is a frequent event, and myoepithelial cells often form microvessels in some large invertebrates. There is no phylogenetic theory about the origin of the endothelial cells in vertebrates. We herein propose that endothelial cells originated from a type of specialized blood cells, called amoebocytes, that adhere to the vascular basement membrane. The transition between amoebocytes and endothelium involved the acquisition of an epithelial phenotype. We suggest that immunological cooperation was the earliest function of these protoendothelial cells. Furthermore, their ability to transiently recover the migratory, invasive phenotype of amoebocytes (i.e., the angiogenic phenotype) allowed for vascular growth from the original visceral areas to the well-developed somatic areas of vertebrates (especially the tail, head, and neural tube). We also hypothesize that pericytes and smooth muscle cells derived from myoepithelial cells detached from the coelomic lining. As the origin of blood cells in invertebrates is probably coelomic, our hypothesis relates the origin of all the elements of the circulatory system with the coelomic wall. We have collected from the literature a number of comparative and developmental data supporting our hypothesis, for example the localization of the vascular endothelial growth factor receptor-2 ortholog in hemocytes of Drosophila or the fact that circulating progenitors can differentiate into endothelial cells even in adult vertebrates. [source] Atom Probe Tomography I. Early Stages of Precipitation of NbC and NbN in Ferritic Steels,ADVANCED ENGINEERING MATERIALS, Issue 12 2006F. Danoix Abstract The results reported in this paper give new information regarding the early stages of precipitation in model low niobium steels. It clearly appears that the kinetic paths for carbides and nitrides precipitation in the investigated model alloys are very different, more continuous in the case of carbides, and through GP zones formation in the case of nitrides. [source] The structural comparison of the bacterial PepX and human DPP-IV reveals sites for the design of inhibitors of PepX activityFEBS JOURNAL, Issue 8 2005Pascal Rigolet X-prolyl dipeptidyl aminopeptidases (X-PDAP) are enzymes catalysing the release of dipeptides from the amino termini of polypeptides containing a proline or an alanine at the penultimate position. Involved in various mammalian regulation processes, as well as in chronic human diseases, they have been proposed to play a role in pathogenicity for Streptococci. We compared the structure of X-PDAP from Lactococcus lactis (PepX) with its human counterpart DPP-IV. Despite very different overall folds, the residues most implicated for X-PDAP activity are conserved in the same positions and orientations in both enzymes, thus defining a structural signature for the X-PDAP specificity that crosses the species frontiers of evolution. Starting from this observation, we tested some inhibitors of DPP-IV on PepX activity, for which no specific inhibitor is known. We thus found that PepX was highly sensitive to valine-pyrrolidide with a KI of 9.3 µm, close to that reported in DPP-IV inhibition. We finally used the structure of PepX from L. lactis as a template for computer-based homology modeling of PepX from the pathogenic Streptococcus gordonii. Docking simulations of valine-pyrrolidide into the active site of PepX led to the identification of key residues for a rational drug design against PepX from Streptococci. These results could have applications in human health giving new perspectives to the struggle against pathogens. [source] Spatial characterization of arbuscular mycorrhizal fungal molecular diversity at the submetre scale in a temperate grasslandFEMS MICROBIOLOGY ECOLOGY, Issue 2 2008Daniel L. Mummey Abstract Although arbuscular mycorrhizal fungi (AMF) form spatially complex communities in terrestrial ecosystems, the scales at which this diversity manifests itself is poorly understood. This information is critical to the understanding of the role of AMF in plant community composition. We examined small-scale (submetre) variability of AMF community composition (terminal restriction fragment length polymorphism fingerprinting) and abundance (extraradical hyphal lengths) in two 1 m2 plots situated in a native grassland ecosystem of western Montana. Extraradical AMF hyphal lengths varied greatly between samples (14,89 m g soil,1) and exhibited spatial structure at scales <30 cm. The composition of AMF communities was also found to exhibit significant spatial autocorrelation, with correlogram analyses suggesting patchiness at scales <50 cm. Supportive of overall AMF community composition analyses, individual AMF ribotypes corresponding to specific phylogenetic groups exhibited distinct spatial autocorrelation. Our results demonstrate that AMF diversity and abundance can be spatially structured at scales of <1 m. Such small-scale heterogeneity in the soil suggests that establishing seedlings may be exposed to very different, location dependent AMF communities. Our results also have direct implications for representative sampling of AMF communities in the field. [source] Chemical variability of Artemisia vulgaris L. essential oils originated from the Mediterranean area of France and CroatiaFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2003I. Jerkovic Abstract The essential oils of Artemisia vulgaris L. originating from France and Croatia were subjected to detailed GC,MS analysis in order to determine possible similarities and differences between them and their chemical compositions, depending on the stage of development. Plant materials were collected in Provence (France) and Dalmatia (Croatia) at four different stages of development: vegetative (June), buds (July), ,owering (August) and seeding (September). Comparison of the chemical composition and content, depending on phenological stages in both localities, shows qualitative similarity, but also the noticeable difference in the amounts of most components. First, the chemical composition of main compounds is very different; Croatian oils are rich in hydrocarbons, which are absent or present in low amounts in French oils. Also, with regard to the yield of essential oils, the yields from Croatian oils were higher (0.09,0.61%) than these from French oil (0.04,0.15%) at each development stage, respectively. Copyright © 2003 John Wiley & Sons, Ltd. [source] Facile Controlled Synthesis and Spectroscopy of CdS1,xSex Alloy and (CdS)1,x@(CdSe)x Core,Shell NanotetrapodsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Mee Rahn Kim Abstract Nanotetrapods of alloy CdS1,xSex and core,shell (CdS)1,x@(CdSe)x are fabricated easily in water using ethylenediamine as a solvent-coordinating molecular template, and then their optical properties are investigated using diverse static and time-resolved spectroscopic methods. The arms of the alloy nanotetrapods have single-crystalline structures of CdS1,xSex without showing staking faults, while the arms of the core,shell nanotetrapods display polycrystalline shell structures of CdSe. The optical properties of CdS1,xSex, where Se atoms are isolated in the CdS lattice, are very different from those of (CdS)1,x@(CdSe)x, where banded CdSe passivates the CdS core. Compared with pure CdS nanotetrapods, the photoluminescence of CdS0.9Se0.1 shifts to the red by 40,nm, whereas that of (CdS)0.9@(CdSe)0.1 does so only by 5,nm. Although the mean luminescence lifetime of alloy CdS1,xSex is shorter than that of pure CdS, it is still much longer than that of core-shell (CdS)1,x@(CdSe)x. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||