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Bottom-up
Terms modified by Bottom-up Selected AbstractsSingle-Molecule Spectroscopy for Plastic Electronics: Materials Analysis from the Bottom-UpADVANCED MATERIALS, Issue 15 2010John M. Lupton Abstract , -conjugated polymers find a range of applications in electronic devices. These materials are generally highly disordered in terms of chain length and chain conformation, besides being influenced by a variety of chemical and physical defects. Although this characteristic can be of benefit in certain device applications, disorder severely complicates materials analysis. Accurate analytical techniques are, however, crucial to optimising synthetic procedures and assessing overall material purity. Fortunately, single-molecule spectroscopic techniques have emerged as an unlikely but uniquely powerful approach to unraveling intrinsic material properties from the bottom up. Building on the success of such techniques in the life sciences, single-molecule spectroscopy is finding increasing applicability in materials science, effectively enabling the dissection of the bulk down to the level of the individual molecular constituent. This article reviews recent progress in single molecule spectroscopy of conjugated polymers as used in organic electronics. [source] Lithographically Patterned Breath Figure of Photoresponsive Small Molecules: Dual-Patterned Honeycomb Lines from a Combination of Bottom-Up and Top-Down LithographyADVANCED MATERIALS, Issue 41 2009Jung Hak Kim A line-patterned breath figure film is achieved using a photo-crosslinkable small molecule through a novel dual-patterning process that combines a breath-figure technique (bottom-up) and photolithography (top-down). The organogelator molecules form honeycomb structures, organizing into supramolecular fibers similar to polymers that stabilize water droplets. [source] Bottom-up, top-down, and within-trophic level pressures on a cactus-feeding insectECOLOGICAL ENTOMOLOGY, Issue 2 2008TOM E. X. MILLER Abstract 1.,The relative importance of host-plants and predators in the population dynamics of herbivorous insects, and the frequency and intensity of inter-specific competition among herbivores, have both been intensively studied and debated. The joint effects of bottom-up, top-down, and within-trophic level interactions, however, have rarely been integrated in a single system. 2.,I studied the dynamics of the cactus bug (Narnia pallidicornis), a specialist feeder on tree cholla cactus (Opuntia imbricata), in response to variable host-plant quality, spider predation, and interactions with cactus-feeding beetles (Moneilema appressum). Previous work suggests that cactus reproductive effort (the proportion of meristems allocated to reproduction) is an important component of host-plant quality for Narnia. I conducted a 2-year field experiment to test the hypotheses that Narnia abundance is positively related to host-plant reproductive effort, and that interactions with predators and putative competitors alter the shape of this relationship. 3.,I found strong support for the first prediction (positive Narnia,plant quality relationship) in both years, but neither predator removal nor beetle exclusion had detectable effects on this relationship in either year. I conclude that the dynamics of this insect herbivore are driven predominantly from the bottom-up, and that available data from this work and from previous studies are too variable to permit broad generalisations for the combined effects of host-plants, predation, and competition on herbivore dynamics. [source] A kaleidoscope as a cyberworld and its animation: linear architecture and modeling based on an incrementally modular abstraction hierarchyCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3-4 2006Tosiyasu L. Kunii Abstract An incrementally modular abstraction hierarchy is known to effectively linearize cyberworlds and virtual worlds, which are combinatorially exploding and hardly managed. It climbs down from general level to specific model preserving the higher level modules as invariants. It not only prevents the combinatorial explosion but also benefits the reuse, development, testing and validation of cyberworld resources. By applying this incrementally modular abstraction hierarchy to a kaleidoscope animation, its architecture and modeling is also specified in this paper as a typical case of cyberworlds. In particular, a homotopy lifting property and a homotopy extension property, which satisfy a duality relation, are also described to show how a kaleidoscope world is systematically created top-down from the whole system and bottom-up from the components. Copyright © 2006 John Wiley & Sons, Ltd. [source] Hierarchical Convex Approximation of 3D Shapes for Fast Region SelectionCOMPUTER GRAPHICS FORUM, Issue 5 2008Marco Attene Abstract Given a 3D solid model S represented by a tetrahedral mesh, we describe a novel algorithm to compute a hierarchy of convex polyhedra that tightly enclose S. The hierarchy can be browsed at interactive speed on a modern PC and it is useful for implementing an intuitive feature selection paradigm for 3D editing environments. Convex parts often coincide with perceptually relevant shape components and, for their identification, existing methods rely on the boundary surface only. In contrast, we show that the notion of part concavity can be expressed and implemented more intuitively and efficiently by exploiting a tetrahedrization of the shape volume. The method proposed is completely automatic, and generates a tree of convex polyhedra in which the root is the convex hull of the whole shape, and the leaves are the tetrahedra of the input mesh. The algorithm proceeds bottom-up by hierarchically clustering tetrahedra into nearly convex aggregations, and the whole process is significantly fast. We prove that, in the average case, for a mesh of n tetrahedra O(n log2 n) operations are sufficient to compute the whole tree. [source] Atlantic climatic factors control decadal dynamics of a Baltic Sea copepod Temora longicornisECOGRAPHY, Issue 5 2003Jari Hänninen We discovered, using transfer functions, that climatic changes in the Atlantic control the abundance of Temora longicornis, a dominant pelagic copepod of the Baltic Sea. The seawater salinity was increasing and copepod numbers were high from 1960s up to 1970s. Then the freshwater runoff started to increase, which resulted in decreasing salinities and abundance of the copepod. At the end of 1990s, runoffs remained at a high level, and the decrease of surface salinities and Temora leveled off. Due to time lags between variables studied, we also make predictions of changes expectable in early 2000s. The total freshwater runoff to the Baltic Sea followed the North Atlantic Oscillation with an immediate lag. Salinity followed the runoff non-linearly with a lag of 4,9 months. Temora longicornis followed the salinity with a lag of 1,3 months. Predicted abundance of T. longicornis will remain low implicating poor feeding conditions for planktivores. Our study points out the importance of physical factors in control of pelagic environments compared to ecological interactions, such as top-down and bottom-up. [source] Bottom-up, top-down, and within-trophic level pressures on a cactus-feeding insectECOLOGICAL ENTOMOLOGY, Issue 2 2008TOM E. X. MILLER Abstract 1.,The relative importance of host-plants and predators in the population dynamics of herbivorous insects, and the frequency and intensity of inter-specific competition among herbivores, have both been intensively studied and debated. The joint effects of bottom-up, top-down, and within-trophic level interactions, however, have rarely been integrated in a single system. 2.,I studied the dynamics of the cactus bug (Narnia pallidicornis), a specialist feeder on tree cholla cactus (Opuntia imbricata), in response to variable host-plant quality, spider predation, and interactions with cactus-feeding beetles (Moneilema appressum). Previous work suggests that cactus reproductive effort (the proportion of meristems allocated to reproduction) is an important component of host-plant quality for Narnia. I conducted a 2-year field experiment to test the hypotheses that Narnia abundance is positively related to host-plant reproductive effort, and that interactions with predators and putative competitors alter the shape of this relationship. 3.,I found strong support for the first prediction (positive Narnia,plant quality relationship) in both years, but neither predator removal nor beetle exclusion had detectable effects on this relationship in either year. I conclude that the dynamics of this insect herbivore are driven predominantly from the bottom-up, and that available data from this work and from previous studies are too variable to permit broad generalisations for the combined effects of host-plants, predation, and competition on herbivore dynamics. [source] Limitation of nesting resources for ants in Colombian forests and coffee plantationsECOLOGICAL ENTOMOLOGY, Issue 5 2006INGE ARMBRECHT Abstract 1.,This study examines limitation of nesting resources for leaf-litter and twig-nesting ants as a mechanism of diversity loss across an intensification gradient of coffee production in Colombia. Twelve farms were selected and classified into four management types: forest, polygeneric shade coffee, monogeneric shade coffee, and sun coffee (unshaded coffee monocultures). 2.,At each of the farms, four treatment subplots were established at the corners of each of 10 25 m2 plots: (i) twig augmentation (adding 10 empty bamboo twigs); (ii) litter augmentation (tripling existing litter profile); (iii) twig and litter augmentation; and (iv) no manipulation control, for a total of 480 subplots. A twig addition experiment was also performed on coffee bushes. 3.,The results showed significantly more ant colonies in the forest and monogeneric shade coffee litter augmentation plots after 4 months. Litter-nesting ant species richness was higher in all three shade systems than in the sun coffee. The identities of ants nesting on coffee bushes were different from those in the soil level litter. Fewer species nested in bamboo twigs placed in litter in the most intensive systems. 4.,More ants nested in the resource addition treatments, and more ant species were found in forested habitats; however, a single mechanism cannot explain the observed patterns. It was concluded that a combination of bottom-up and top-down effects might lead to the loss of associated fauna with the intensification of these agroecosystems. [source] Wedged between bottom-up and top-down processes: aphids on tansyECOLOGICAL ENTOMOLOGY, Issue 1 2004Bernhard Stadler Abstract., 1. Many species of aphids exploit a single host-plant species and have to cope with changing environmental conditions. They often vary greatly in abundance even when feeding on the same host. In a field experiment, the bottom-up (plant quality/patch type frequency) and top-down (ant attendance/predation) effects on the abundance of four species of aphids feeding on tansy (Tanacetum vulgare) were tested using a full factorial design. In addition, a model was used to examine these patch characteristics for their relative effects on the population dynamics and abundance of different aphid species. 2. Aphid numbers changed significantly depending on the quality of the host plant and the presence/absence of attending ants. The obligate myrmecophile, Metopeurum fuscoviride, was abundant on high-quality plants, while on poor quality plants or on plants without attending ants these aphids did not survive until the end of the experiment. The facultative myrmecophiles, Aphis fabae and Brachycaudus cardui, and the unattended aphid species, Macrosiphoniella tanacetaria, all reached similar peak population densities, but M. tanacetaria did best in poor quality patches. 3. Natural enemies reduced aphid numbers, but those species feeding on high-quality plants survived longer than those on poor-quality plants, which existed only for a short period of time, especially when associated with ants. Losses due to migration of winged morphs and mortality caused by parasitoids were insignificant. 4. Varying the frequency of different patch types in a model indicates that different degrees of associations with ants are favoured in different environments. If the proportion of high-quality patches in a habitat is large, obligate myrmecophiles do best. On increasing the number of poor-quality patches, unattended species become more abundant. 5. The results suggest that, in spite of large species specific differences in growth rates, degree of myrmecophily or life cycle features, the temporal and spatial variability in top-down and bottom-up forces differentially affects aphid species and allows the simultaneous exploitation of a shared host-plant species. [source] Reconciling differences in trophic control in mid-latitude marine ecosystemsECOLOGY LETTERS, Issue 10 2006Kenneth T. Frank Abstract The dependence of long-term fishery yields on primary productivity, largely based on cross-system comparisons and without reference to the potential dynamic character of this relationship, has long been considered strong evidence for bottom-up control in marine systems. We examined time series of intensive empirical observations from nine heavily exploited regions in the western North Atlantic and find evidence of spatial variance of trophic control. Top-down control dominated in northern areas, the dynamics evolved from bottom-up to top-down in an intermediate region, and bottom-up control governed the southern areas. A simplified, trophic control diagram was developed accounting for top-down and bottom-up forcing within a larger region whose base state dynamics are bottom-up and can accommodate time-varying dynamics. Species diversity and ocean temperature co-varied, being relatively high in southern areas and lower in the north, mirroring the shifting pattern of trophic control. A combination of compensatory population dynamics and accelerated demographic rates in southern areas seems to account for the greater stability of the predator species complex in this region. [source] Predator disease out-break modulates top-down, bottom-up and climatic effects on herbivore population dynamicsECOLOGY LETTERS, Issue 4 2006Christopher C. Wilmers Abstract Human-introduced disease and climatic change are increasingly perturbing natural ecosystems worldwide, but scientists know very little about how they interact to affect ecological dynamics. An outbreak of canine parvovirus (CPV) in the wolf population on Isle Royale allowed us to test the transient effects of an introduced pathogen and global climatic variation on the dynamics of a three-level food chain. Following the introduction of CPV, wolf numbers plummeted, precipitating a switch from top-down to bottom-up regulation of the moose population; consequently, the influence of climate on moose population growth rate doubled. This demonstrates that synergistic interactions between pathogens and climate can lead to shifts in trophic control, and suggests that predators in this system may play an important role in dampening the effects of climate change on the dynamics of their prey. [source] Trade-offs in oviposition choice?ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2007Food-dependent performance, defence against predators of a herbivorous sawfly Abstract The sawfly Athalia rosae L. (Hymenoptera: Tenthredinidae) is a feeding specialist on plant species of the Brassicaceae, which are characterised by secondary metabolites, called glucosinolates. The larvae can take up the respective glucosinolates of their hosts and concentrate them in their haemolymph to protect themselves against predators. Oviposition preferences of naïve females were tested for three species, Sinapis alba L., Brassica nigra (L.) Koch, and Barbarea stricta Andrz., and were related to larval performance patterns. Larvae were reared on either one of these plants and it was investigated how host-plant quality influences both the developmental times and growth of larvae (bottom-up) and the defence efficiency against predators (top-down). Innately, almost all adult females avoided B. stricta for oviposition and clearly preferred B. nigra over S. alba. On average, larvae developed best on B. nigra. Female larvae reached similar final body masses on all host-plant species, but males reared on S. alba were slightly lighter. The developmental time of larvae reared on B. stricta was significantly longer than on the other two plants. However, larvae reared on B. stricta were best protected against the predatory wasp Polistes dominulus Christ (Hymenoptera: Vespidae). The wasps rejected these larvae most often, while they attacked larvae reared on S. alba most frequently. Thus, larvae feeding on B. stricta theoretically run a higher risk of predation due to a prolonged developmental time, but in practice they are better protected against predators. Overall, oviposition preferences of A. rosae seem to be more influenced by bottom-up effects on larval performance than by top-down effects. [source] Governing long-term social,ecological change: what can the adaptive management and transition management approaches learn from each other?ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 1 2009Timothy J. Foxon Abstract Maintaining social welfare and opportunity in the face of severe ecological pressures requires frameworks for managing and governing long-term social,ecological change. In this paper we analyse two recent frameworks, adaptive management and transition management, outlining what they could learn from each other. Though usually applied in different domains, the two conceptual frameworks aim to integrate bottom-up and top-down approaches, and share a focus on the ability of systems to learn and develop adaptive capacity whilst facing external shocks and long-term pressures. Both also emphasize learning from experimentation in complex systems, but transition management focuses more on the ability to steer long-term changes in system functions, whilst adaptive management emphasizes the maintenance of system functions in the face of external change. The combination of iterative learning and stakeholder participation from adaptive management has the potential to incorporate vital feedbacks into transition management, which in turn offers a longer-term perspective from which to learn about and manage socio-technical and social,ecological change. It is argued that by combining insights from both frameworks it may be possible to foster more robust and resilient governance of social,ecological systems than could be achieved by either approach alone. The paper concludes by critically reflecting upon the challenges and benefits of combining elements of each approach, as has been attempted in the methodology of a research project investigating social,ecological change in UK uplands. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment. [source] Directions in Rural Development Policy , Lessons from Both Sides of the Atlantic Richtlinien für die ländliche Entwicklungspolitik , Beispiele von diesseits und jenseits des Atlantiks Les orientations de la politique de développement rural , Enseignements en provenance des deux côtés de l'AtlantiqueEUROCHOICES, Issue 1 2008David Blandford Directions in Rural Development Policy , Lessons from Both Sides of the Atlantic A workshop comparing rural development policies in Europe and the US found differences in the social values that shape them. These include different attachments to place, concerns with lagging regions, and interests in the assessment of public interventions. There is also a difference in coverage. In the EU environmental and landscape issues form part of the CAP's Rural Development Pillar, using agriculture as an instrument, whereas in the US these are handled by other policies, some of which can claim deeper historical roots. In the context of rural development policy, the EU attaches intrinsic value to the environment, while in the US the focus is more on economic spin-offs from environmental quality. There are also differences in governance; a complete US view requires taking in Federal, State and local initiatives whereas in the EU a more organised framework is apparent. Nevertheless, when policy is viewed from a bottom-up perspective many common features are found. Improving human and social capital and infrastructure are key factors to stimulating economic development on both sides of the Atlantic, though only some of these drivers form part of the CAP's Pillar II. While in the EU the role of rural development is set to expand, this is far less certain in the US where the emphasis on agricultural support is likely to continue to dominate the political agenda. Les orientations de la politique de développement rural , Enseignements en provenance des deux côtés de l'Atlantique Un atelier comparant les politiques de développement rural en Europe et aux États-Unis a mis en évidence des différences entre les valeurs sociales sur lesquelles sont fondées ces politiques. Ces différences concernent entre autre l'attachement à des lieux particuliers, l'inquiétude pour les régions en retard de croissance, et l'intérêt pour une évaluation des pouvoirs publics. Les différences portent aussi sur l'étendue de la question. Dans l'Union européenne, les questions portant sur le paysage et l'environnement sont abordées dans le cadre du pilier de la PAC sur le développement rural, qui porte sur l'agriculture comme instrument du développement rural, alors qu'aux États-Unis, ces questions sont traitées par d'autres politiques dont certaines remontent à loin. Dans le contexte de la politique de développement rural, l'Union européenne attache une valeur intrinsèque à l'environnement tandis qu'aux États-Unis, l'accent est mis plutôt sur les retombées économiques d'un environnement de qualité. Les différences portent également sur la gouvernance : pour avoir une vue d'ensemble sur les États-Unis, il faut considérer les actions aux niveaux fédéral, des États et du local alors que dans l'Union européenne, un cadre plus organisé est apparent. Cependant, dans le cas de politiques partant de la base (bottom-up), de nombreux points communs existent. L'amélioration du capital social et humain, et celle des infrastructures sont des éléments clés pour stimuler le développement économique des deux côtés de l'Atlantique, même si seuls quelques uns de ces facteurs sont compris dans le deuxième pilier de la PAC. Alors que le rôle du développement rural devrait s'étendre dans l'Union européenne, c'est beaucoup moins certain aux États-Unis où l'accent sur le soutien à l'agriculture continuera probablement à dominer l'ordre du jour de la politique. Richtlinien für die ländliche Entwicklungspolitik , Beispiele von diesseits und jenseits des Atlantiks Im Rahmen eines Workshops wurden europäische und US-amerikanische Politikmaßnahmen zur Entwicklung des ländlichen Raums miteinander verglichen. Die Ergebnisse zeigen, dass sich die gesellschaftlichen Werte für die Ausgestaltung der Politikmaßnahmen im Hinblick auf Ortsverbundenheit, die Belange der rückständigen Regionen und das Interesse bei der Bewertung öffentlicher Interventionen unterscheiden. Die jeweiligen Geltungsbereiche unterscheiden sich ebenfalls. In der EU bilden Fragestellungen in Bezug auf Umwelt und landschaftliche Gestaltung einen Teil der zweiten Säule der GAP (Entwicklung des ländlichen Raums), und die Landwirtschaft ist dabei ein Mittel zum Zweck. In den USA hingegen werden diese Fragestellungen durch andere Politikmaßnahmen abgedeckt, von denen einige über längere historische Wurzeln verfügen. Im Rahmen der Politik zur Entwicklung des ländlichen Raums misst die EU der Umwelt intrinsischen Wert bei, während sich die USA mehr auf aus der Umweltqualität resultierende wirtschaftliche Nebeneffekte konzentriert. Im Hinblick auf die Governance sind ebenfalls Unterschiede vorhanden: Während es im Falle der USA erforderlich ist, in einer Gesamtbetrachtung die Initiativen auf staatlicher, bundesstaatlicher und kommunaler Ebene zu berücksichtigen, lassen die Rahmenbedingungen in Europa ein höheres Maß an Organisation erkennen. Wird die Politik jedoch aus einer Bottom-up-Perspektive heraus betrachtet, können zahlreiche Gemeinsamkeiten gefunden werden. Bei der Verbesserung des Human- und Sozialkapitals und der Infrastruktur handelt es sich um Schlüsselfaktoren für die Ankurbelung der wirtschaftlichen Entwicklung diesseits und jenseits des Atlantiks, wenngleich nur einige dieser Triebfedern die zweite Säule der GAP ausmachen. Während die Entwicklung des ländlichen Raums in der EU eine immer größere Rolle spielen wird, ist dies in den USA längst nicht sicher; dort wird der Schwerpunkt auf die Agrarstützung wahrscheinlich weiterhin die politische Agenda dominieren. [source] Bulk Nanostructured Materials: Non-Mechanical Synthesis,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Yulia Ivanisenko An overview of the synthesis and processing techniques for bulk nanostructured materials that are based on "bottom-up" approaches is presented. Typically, these processes use nanoparticles, which can be produced by a variety of methods in the gas, liquid or solid state, as the basic building blocks. Their assembly into bulk nanostructured materials requires at least one more processing step, such as compaction or the formation of thick films. For certain nanostructures, film deposition techniques can also be employed. A wide range of nanostructures , from thick films with theoretical density to bulk nanocrystalline materials with nanoporosity , exhibiting novel structural and functional properties useful in many fields of applications are presented. Additionally, the properties of these bulk nanostructured materials can be categorized as either tailored, i.e., microstructure-dependent and inherently irreversible, or tunable, i.e., reversible by the application of an external field. Examples of both categories of properties are presented and the special role of the synthesis and processing routes to achieve the necessary nanostructures is emphasized. [source] Activity in the superior colliculus reflects dynamic interactions between voluntary and involuntary influences on orienting behaviourEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2008Andrew H. Bell Abstract Performance in a behavioural task can be influenced by both bottom-up and top-down processes such as stimulus modality and prior probability. Here, we exploited differences in behavioural strategy to explore the role of the intermediate and deep layers of the superior colliculus (dSC) in covert orienting. Two monkeys were trained on a predictive cued-saccade task in which the cue predicted the target's upcoming location with 80% validity. When the delay between cue and target onset was 250 ms, both monkeys showed faster responses to the uncued (Invalid) location. This was associated with a reduced target-aligned response in the dSC on Valid trials for both monkeys and is consistent with a bottom-up (i.e. involuntary) bias. When the delay was increased to 650 ms, one monkey continued to show faster responses to the Invalid location whereas the other monkey showed faster responses to the Valid location, consistent with a top-down (i.e. voluntary) bias. This latter behaviour was correlated with an increase in activity in dSC neurons preceding target onset that was absent in the other monkey. Thus, using the information provided by the cue shifted the emphasis towards top-down processing, while ignoring this information allowed bottom-up processing to continue to dominate. Regardless of the selected strategy, however, neurons in the dSC consistently reflected the current bias between the two processes, emphasizing its role in both the bottom-up and top-down control of orienting behaviour. [source] Effect of Contact Mode on the Electrical Transport and Field-Emission Performance of Individual Boron NanowiresADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Fei Liu Abstract Vapor,liquid,solid processing of boron nanowires (BNWs) can be carried out either using a bottom-up or top-down growth mode, which results in different contact modes between the nanowire and the substrate. The contact mode may strongly affect the electrical transport and field-emission performance of the individual boron nanowires grown on a Si substrate. The electrical transport and field-emission characteristics of individual boron nanowires of different contact modes are investigated in situ using a scanning electron microscope. The contact barriers are very distinct for the different contact modes. Moreover, the transition from a "contact-limited" to a "bulk-limited" field-emission (FE) process is demonstrated in nanoemitters for the first time, and the proposed improved metal,insulator,vacuum (MIV) model may better illustrate the nonlinear behavior of the Fowler-Nordheim (FN) plots in these nanoscale systems. Individual BNWs with different contact modes have a discrepancy in their emission stability and vacuum breakdown characteristics though they have similar aspect ratios, which suggests that their electrical transport and field-emission performance are closely related to their contact mode. Boron nanowires grown in the base-up mode have better field-emission performances and are more beneficial than those grown in the top-down mode for various device applications. [source] Ecosystem controls of juvenile pink salmon (Onchorynchus gorbuscha) and Pacific herring (Clupea pallasi) populations in Prince William Sound, AlaskaFISHERIES OCEANOGRAPHY, Issue 2001Robert T. Cooney Abstract Five years of field, laboratory, and numerical modelling studies demonstrated ecosystem-level mechanisms influencing the mortality of juvenile pink salmon and Pacific herring. Both species are prey for other fishes, seabirds, and marine mammals in Prince William Sound. We identified critical time-space linkages between the juvenile stages of pink salmon and herring rearing in shallow-water nursery areas and seasonally varying ocean state, the availability of appropriate zooplankton forage, and the kinds and numbers of predators. These relationships defined unique habitat dependencies for juveniles whose survivals were strongly linked to growth rates, energy reserves, and seasonal trophic sheltering from predators. We found that juvenile herring were subject to substantial starvation losses during a winter period of plankton diminishment, and that predation on juvenile pink salmon was closely linked to the availability of alternative prey for fish and bird predators. Our collaborative study further revealed that juvenile pink salmon and age-0 herring exploit very different portions of the annual production cycle. Juvenile pink salmon targeted the cool-water, early spring plankton bloom dominated by diatoms and large calanoid copepods, whereas young-of-the-year juvenile herring were dependent on warmer conditions occurring later in the postbloom summer and fall when zooplankton was composed of smaller calanoids and a diversity of other taxa. The synopsis of our studies presented in this volume speaks to contemporary issues facing investigators of fish ecosystems, including juvenile fishes, and offers new insight into problems of bottom-up and top-down control. In aggregate, our results point to the importance of seeking mechanistic rather than correlative understandings of complex natural systems. [source] An Investigation of Reading Strategies Applied by American Learners of Chinese as a Foreign LanguageFOREIGN LANGUAGE ANNALS, Issue 4 2008Li-Chun Lee-Thompson Assistant ProfessorArticle first published online: 19 MAR 200 Abstract: Minimal research has been conducted in reading Chinese as a second/ foreign language (CSI/CFL). In an effort to further the understanding of the reading process, this study, utilizing think aloud and retelling procedures, focuses on the identification of strategies that American university students applied to read Chinese texts (narrative and argumentative), and the difficulties encountered when processing texts for meaning. Also it examines whether Bernhardt's constructivist model can account for the reading process of the CFL learners at the intermediate proficiency level. The results show that the CFL readers employed bottom-up and top-down processing strategies, that their difficulties were pertinent to vocabulary, orthography, grammar, and background knowledge, and that Bernhardt's reading model could account for the reading process of CFL learners with minor modification. [source] Can America Finance Freedom?FOREIGN POLICY ANALYSIS, Issue 4 2009Assessing U.S. Democracy Promotion via Economic Statecraft Recent discourse on U.S. efforts to promote democracy has focused on military activities; especially the strategic and normative perils of democracy promotion at the point of bayonets. This paper explores the United States' use of economic statecraft to foster democratization, with particular attention to democracy incentive and assistance strategies. Incentive approaches attempt to promote democracy from the top-down, by leveraging aid and trade privileges to persuade authoritarian leaders to implement political reform. Assistance approaches aim to induce democratization from the inside, through funding and technical assistance to state institutions, and from the bottom-up, by providing support to civil society and elections. This study finds that while top-down incentive approaches can stimulate democratic change, this strategy tends to work only when aid and trade benefits are conditional; that is, when benefits are withheld until recipient states meet rigorous democratic benchmarks. Washington has historically eschewed democratic conditionality, however, and thus can claim very few aid-induced or trade-induced democratization events. Scant evidence exists to demonstrate that inside approaches,that is, institutional aid,possesses significant capacity to induce democracy. It is the bottom-up approach,empowering the masses to compel democratic change,that has registered the greatest number of democracy promotion successes. [source] Linking ecological theory with stream restorationFRESHWATER BIOLOGY, Issue 4 2007P. S. LAKE Summary 1. Faced with widespread degradation of riverine ecosystems, stream restoration has greatly increased. Such restoration is rarely planned and executed with inputs from ecological theory. In this paper, we seek to identify principles from ecological theory that have been, or could be, used to guide stream restoration. 2. In attempts to re-establish populations, knowledge of the species' life history, habitat template and spatio-temporal scope is critical. In many cases dispersal will be a critical process in maintaining viable populations at the landscape scale, and special attention should be given to the unique geometry of stream systems 3. One way by which organisms survive natural disturbances is by the use of refugia, many forms of which may have been lost with degradation. Restoring refugia may therefore be critical to survival of target populations, particularly in facilitating resilience to ongoing anthropogenic disturbance regimes. 4. Restoring connectivity, especially longitudinal connectivity, has been a major restoration goal. In restoring lateral connectivity there has been an increasing awareness of the riparian zone as a critical transition zone between streams and their catchments. 5. Increased knowledge of food web structure , bottom-up versus top-down control, trophic cascades and subsidies , are yet to be applied to stream restoration efforts. 6. In restoration, species are drawn from the regional species pool. Having overcome dispersal and environmental constraints (filters), species persistence may be governed by local internal dynamics, which are referred to as assembly rules. 7. While restoration projects often define goals and endpoints, the succession pathways and mechanisms (e.g. facilitation) by which these may be achieved are rarely considered. This occurs in spite of a large of body of general theory on which to draw. 8. Stream restoration has neglected ecosystem processes. The concept that increasing biodiversity increases ecosystem functioning is very relevant to stream restoration. Whether biodiversity affects ecosystem processes, such as decomposition, in streams is equivocal. 9. Considering the spatial scale of restoration projects is critical to success. Success is more likely with large-scale projects, but they will often be infeasible in terms of the available resources and conflicts of interest. Small-scale restoration may remedy specific problems. In general, restoration should occur at the appropriate spatial scale such that restoration is not reversed by the prevailing disturbance regime. 10. The effectiveness and predictability of stream ecosystem restoration will improve with an increased understanding of the processes by which ecosystems develop and are maintained. Ideas from general ecological theory can clearly be better incorporated into stream restoration projects. This will provide a twofold benefit in providing an opportunity both to improve restoration outcomes and to test ecological theory. [source] On the different nature of top-down and bottom-up effects in pelagic food websFRESHWATER BIOLOGY, Issue 12 2002Z. Maciej Gliwicz SUMMARY 1.,Each individual planktonic plant or animal is exposed to the hazards of starvation and risk of predation, and each planktonic population is under the control of resource limitation from the bottom up (growth and reproduction) and by predation from the top down (mortality). While the bottom-up and top-down impacts are traditionally conceived as compatible with each other, field population-density data on two coexisting Daphnia species suggest that the nature of the two impacts is different. Rates of change, such as the rate of individual body growth, rate of reproduction, and each species' population growth rate, are controlled from the bottom up. State variables, such as biomass, individual body size and population density, are controlled from the top down and are fixed at a specific level regardless of the rate at which they are produced. 2.,According to the theory of functional responses, carnivorous and herbivorous predators react to prey density rather than to the rate at which prey are produced or reproduced. The predator's feeding rate (and thus the magnitude of its effect on prey density) should hence be regarded as a functional response to increasing resource concentration. 3.,The disparity between the bottom-up and top-down effects is also apparent in individual decision making, where a choice must be made between accepting the hazards of hunger and the risks of predation (lost calories versus loss of life). 4.,As long as top-down forces are effective, the disparity with bottom-up effects seems evident. In the absence of predation, however, all efforts of an individual become subordinate to the competition for resources. Biomass becomes limited from the bottom up as soon as the density of a superior competitor has increased to the carrying capacity of a given habitat. Such a shift in the importance of bottom-up control can be seen in zooplankton in habitats from which fish have been excluded. [source] MONEY FLOWS LIKE MERCURY: THE GEOGRAPHY OF GLOBAL FINANCEGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 2 2005Gordon L Clark ABSTRACT. If the social relations and inherited configuration of production were at the core of economic geography a decade ago, these aspects of the world are increasingly taken for granted. The global scope of industry and corporate strategy has claimed increasing attention over the past decade. And while any ,new' economic geography must have something to say about the nature of human agency and the role of institutions in structuring the landscape, care must be taken not to exaggerate their significance for constructive interaction. In point of fact, the global finance industry is an essential lens through which to study contemporary capitalism from the top-down and the bottom-up. If we are to understand the economic landscape of twenty-first century capitalism, it should be understood through global financial institutions, its social formations and investment practices. This argument is developed by reference to the recent literature on the geography of finance and a metaphor , money flows like mercury , designed to explicate the spatial and temporal logic of global capital flows. Some may dispute this argument, but in doing so they lament the passing of an era rather than advancing a convincing counterclaim about how the world is and what it might become. All this means that we have to rethink the significance of geographical scale and organizational processes as opposed to an unquestioned commitment to localities. [source] On becoming a process-enabled organization: How to seed a culture of quality in a postacquisition environmentGLOBAL BUSINESS AND ORGANIZATIONAL EXCELLENCE, Issue 2 2010Charles Parker Misaligned processes and disparate cultures can plague M&As for years after the deals close. As this case study illustrates, a practical yet inexpensive approach can drive process improvement and quality in a transition-weary, cost-wary organization through organic bottom-up and top-down change. The author discusses a model of process evolution in organizations and the potentially disruptive effect of M&As, particularly successive deals. He then describes a relatively simple statistical method for assessing process quality; its successful application in a postacquisition environment; and organizational considerations, including influence models and the role of sponsors and champions, for shepherding an organization toward greater process quality and rigor. © 2010 Wiley Periodicals, Inc. [source] Lithographically Patterned Breath Figure of Photoresponsive Small Molecules: Dual-Patterned Honeycomb Lines from a Combination of Bottom-Up and Top-Down LithographyADVANCED MATERIALS, Issue 41 2009Jung Hak Kim A line-patterned breath figure film is achieved using a photo-crosslinkable small molecule through a novel dual-patterning process that combines a breath-figure technique (bottom-up) and photolithography (top-down). The organogelator molecules form honeycomb structures, organizing into supramolecular fibers similar to polymers that stabilize water droplets. [source] The role of soil community biodiversity in insect biodiversityINSECT CONSERVATION AND DIVERSITY, Issue 3 2010ALISON BENNETT Abstract., 1.,This study demonstrates that feedback loops between plants and insects contribute to both plant and insect diversity. Synthesis of several studies reveals that both bottom-up and top-down forces are important for plant and insect communities. 2.,Feedback loops between plants and soil organisms contribute to plant and soil diversity. An analysis of multiple systems reveals that pathogens, mutualists, and a wide variety of soil fauna directly influence, and are influenced by, plant diversity. 3.,The connection of plant,insect and soil,plant feedback loops leads to the maintenance of all three groups, and the maintenance of these feedback loops crucially affects insect diversity. Examples of the influence of soil community diversity on insect diversity, and the influence of insect diversity on soil community diversity, as well as feedbacks through all three trophic levels are provided. 4.,Finally, means of conserving and restoring soil communities to influence the conservation and restoration of insect communities are discussed. [source] The Northern Irish Peace Process: From Top to BottomINTERNATIONAL STUDIES REVIEW, Issue 2 2008Landon E. Hancock Like the conflict in Northern Ireland, the peace process has the distinction of being one of the longest-running processes both in the time required to reach an agreement and in the time required for implementation of that agreement. This article analyzes the peace process from the perspectives of elite negotiations to community relations and in between in order to determine how each of these peace processes within the overall peace process contributed its longevity and overall success. The distinction that peace is made from the top-down is contrasted with the notion that it cannot succeed without social preparation through bottom-up, or middle-out initiatives; concluding with analysis of frameworks that attempt to capture the entirety of the peace process and what its success means for the study of the Northern Irish peace process and peace processes in general. [source] A new vision for the field: Introduction to the second special issue on the unified theoryJOURNAL OF CLINICAL PSYCHOLOGY, Issue 1 2005Gregg R. Henriques This is the second of two issues of the Journal of Clinical Psychology focused on the validity and usefulness of a new theoretical vision for the field (Henriques, 2003). The first two contributions from Rand and Ilardi and Geary both enrich the argument that psychology needs to be effectively connected with biology and physics and that the unified theory (via Behavioral Investment Theory) is highly successful in this way. The authors of the subsequent three articles,Shaffer, Quackenbush, and Shealy,show that the Tree of Knowledge System (through the Justification Hypothesis) is deeply commensurate with the dominant paradigms in the social sciences. Thus, the group of authors of these five articles demonstrates the viability of the unified theory both from bottom-up and top-down viewpoints. In the sixth article, the author addresses some important problems that potentially arise with the development of a clearly defined discipline. In the concluding article I address the concerns about the proposal raised by the contributors to the two special issues and articulate how the unified theory lays the foundation for the development of a useful mass movement in psychology. © 2004 Wiley Periodicals, Inc. J Clin Psychol. [source] Strong Societies, Wed Parties: Regime Change in Cuba and Venzula in the 1950s and TodayLATIN AMERICAN POLITICS AND SOCIETY, Issue 2 2001Jauier Cowales ABSTRACT The literature on the origins of democratic institutions is split between bottom-up and top-down approaches. The former emphasize societal factors that press for democracy; the latter, rules and institutions that shape elites' incentives. Can these approaches be reconciled? This article proposes competitive political parties, more so than degrees of modernization and associationalism, as the link between the two. Competitive political parties enhance society's bargaining power with the state and show dominant elites that liberalization is in their best interest; the parties are thus effective conduits of democracy. In the context of party deficit, the prospects for democratization or redemocratization are slim. This is illustrated by comparing Cuba and Venezuela in the 1950s and 1330s. [source] Institutional Vulnerablity and Opportunity: Immigration and America's "War on Terror"LAW & SOCIAL INQUIRY, Issue 4 2006Elizabeth Heger Boyle New legal realism focuses on the complexity of individual action and the view of law from the "bottom-up." Neoinstitutionalism also suggests that rational-actor models are too simplistic, but spotlights enduring historical effects on individual action and thus tends to view the world from the "top-down." In this article, we seek to marry the two disparate approaches by centering on moments of institutional vulnerability and opportunity when a system can change or be redefined. The terrorist attacks on September 11 provided a unique opportunity for institutional change. Policymakers seized this opportunity to introduce reforms into American immigration law that fundamentally altered how that law is administered. The implications of these legal reforms were to group many migrants into the category of potential "terrorist" and to make it increasingly difficult for any migrant to claim "victim" status. Immigrants responded to these reforms by refraining from public criticism of the United States and by becoming American citizens. We discuss the potential implications of those actions on the institution of citizenship. [source] | ||||||||||||||||||||||||||||||||||||||||||||||