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Top-down
Terms modified by Top-down Selected AbstractsTop-down and bottom-up regulation of herbivores: Spodoptera frugiperda turns tables on endophyte-mediated plant defence and virulence of an entomopathogenic nematodeECOLOGICAL ENTOMOLOGY, Issue 3 2004Douglas S. Richmond Abstract., 1. The fungus Neotyphodium lolii forms a symbiotic relationship with its grass host Lolium perenne (perennial ryegrass). The fungus benefits from access to plant nutrients and photosynthate, whereas the plant benefits from acquired chemical defence against herbivory. 2. This study examined the potential for endophyte-mediated plant defences to influence interactions between fall armyworm Spodoptera frugiperda, and the entomopathogenic nematode Steinernema carpocapsae and clarified biological mechanisms underlying the observations made. 3. In laboratory and greenhouse experiments, S. frugiperda larvae were fed endophytic or non-endophytic L. perenne then exposed to S. carpocapsae or injected with the nematodes' symbiotic bacteria Xenorhabdus nematophila. 4. In all instances, S. frugiperda larvae fed endophyte-infected grass suffered significantly lower mortality than those fed non-endophytic plants. Although larvae fed endophyte-infected grass often had significantly lower biomass than those fed uninfected grass, these differences did not account for altered susceptibility to S. carpocapsae. 5. Endophyte-mediated reductions in herbivore susceptibility to the nematode pathogen represent a herbivore adaptation that effectively turns the tables on both plant and natural enemy by reducing the virulence of the nematodes' symbiotic bacteria while expanding the temporal window of herbivory. [source] Top-down and bottom-up diversity cascades in detrital vs. living food websECOLOGY LETTERS, Issue 1 2003Lee A. Dyer Abstract Apex predators and plant resources are both critical for maintaining diversity in biotic communities, but the indirect (,cascading') effects of top-down and bottom-up forces on diversity at different trophic levels are not well resolved in terrestrial systems. Manipulations of predators or resources can cause direct changes of diversity at one trophic level, which in turn can affect diversity at other trophic levels. The indirect diversity effects of resource and consumer variation should be strongest in aquatic systems, moderate in terrestrial systems, and weakest in decomposer food webs. We measured effects of top predators and plant resources on the diversity of endophytic animals in an understorey shrub Piper cenocladum (Piperaceae). Predators and resource availability had significant direct and indirect effects on the diversity of the endophytic animal community, but the effects were not interactive, nor were they consistent between living vs. detrital food webs. The addition of fourth trophic level beetle predators increased diversity of consumers supported by living plant tissue, whereas balanced plant resources (light and nutrients) increased the diversity of primary through tertiary consumers in the detrital resources food web. These results support the hypotheses that top-down and bottom-up diversity cascades occur in terrestrial systems, and that diversity is affected by different factors in living vs. detrital food webs. [source] Top-down and bottom-up control in an eelgrass,epiphyte systemOIKOS, Issue 5 2008Sybill Jaschinski Nutrient supply and the presence of grazers can control primary producers in aquatic ecosystems, but the relative importance of bottom-up and top-down effects remains inconclusive. We conducted a mesocosm experiment and a field study to investigate the independent and interactive effects of nutrient enrichment and grazing on primary producers in an eelgrass bed Zostera marina. Nutrient treatments consisted of ambient or enriched (2× and 4× ambient) concentrations of inorganic nitrogen and phosphate. Grazer treatments consisted of presence or absence of field densities of the common isopod Idotea baltica. We found strong and interacting effects of nutrients and grazing on epiphytes. Epiphyte biomass and productivity were enhanced by nutrient enrichment and decreased in the presence of grazers. The absolute amount of epiphyte biomass consumed by grazers increased under high nutrient supply, and thus, nutrient effects were stronger in the absence of grazing. The effects of grazers and fertilisation on epiphyte composition were antagonistic: chain-forming diatoms and filamentous algae profited from nutrient enrichment, but their proportions were reduced by grazing. Eelgrass growth was positively affected by grazing and by nutrient enrichment at moderate nutrient concentrations. High nutrient supply reduced eelgrass productivity compared to moderate nutrient conditions. The monthly measured field data showed a nitrogen limitation for epiphytes and eelgrass in summer, which may explain the positive effect of nutrient enrichment on both primary producers. Generally, the field data suggested the possibility of seasonally varying importance of bottom-up and top-down control on primary producers in this eelgrass system. [source] Stability of pitcher-plant microfaunal populations depends on food web structureOIKOS, Issue 1 2005M. Kurtis Trzcinski Enrichment (increasing K) destabilizes simple consumer,resource interactions, but increasing food web complexity in various ways can remove this paradox of enrichment. We varied resources and number of omnivorous predators (mosquitoes) and tested for effects on the stability (persistence and temporal variability) of microfaunal populations living in pitcher plants. Top-down (omnivorous) effects were destabilizing, decreasing the persistence time of a rotifer, Habrotrocha rosa, and perhaps a microflagellate, Bodo sp. Enrichment effects were more complex, in part due to effects of shredding midges on resource availability, and in part due to interactions with predation. The persistence of Bodo increased with resource availability (more bacteria due to shredding by midges; no paradox of enrichment). Increasing resources by adding ants decreased persistence of H. rosa when mosquitoes were rare (paradox of enrichment), but the effect was reversed in leaves with significant colonization by mosquitoes. Thus, in the microfaunal community of pitcher plants, omnivorous predation tends to be destabilizing, and also tends to remove the paradox of enrichment. [source] Top-down processed silicon nanowire transistor arrays for biosensingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2009Xuan Thang Vu Abstract We describe the fabrication, electrical and electrochemical characterization of silicon nanowire arrays, which were processed in a top-down approach using combined nanoimprint lithography and wet chemical etching. We used the top silicon layer as contact line and observed an influence of implantation and subsequent annealing of these lines to the device performance. In addition we found a subthreshold slope dependence on wire size. When operated in a liquid environment, wires can be utilized as pH sensors. We characterized the pH sensitivity in the linear range and in the subthreshold operation regime. As a first proof-of-principle experiment for the later use of the sensors in bioassays, we monitored the buildup of polyelectrolyte multilayers on the wire surface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [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] Community Driven Development, Collective Action and Elite Capture in IndonesiaDEVELOPMENT AND CHANGE, Issue 2 2007Aniruddha Dasgupta ABSTRACT In response to the well documented limitations of top-down, modernist and authoritarian approaches that have dominated development, practitioners and academics increasingly promote more community-based approaches. The World Bank uses the term ,community driven development' to describe projects that increase a community's control over the development process. In an analysis of a community driven poverty alleviation project in Indonesia, this article examines the vulnerability of such an approach to elite capture. The expected relationships among a community's capacity for collective action, elite control over project decisions and elite capture of project benefits were not found. In cases where the project was controlled by elites, benefits continued to be delivered to the poor, and where power was the most evenly distributed, resource allocation to the poor was restricted. Communities where both non-elites and elites participated in democratic self-governance, however, did demonstrate an ability to redress elite capture when it occurred. [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] 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] Top-down and bottom-up diversity cascades in detrital vs. living food websECOLOGY LETTERS, Issue 1 2003Lee A. Dyer Abstract Apex predators and plant resources are both critical for maintaining diversity in biotic communities, but the indirect (,cascading') effects of top-down and bottom-up forces on diversity at different trophic levels are not well resolved in terrestrial systems. Manipulations of predators or resources can cause direct changes of diversity at one trophic level, which in turn can affect diversity at other trophic levels. The indirect diversity effects of resource and consumer variation should be strongest in aquatic systems, moderate in terrestrial systems, and weakest in decomposer food webs. We measured effects of top predators and plant resources on the diversity of endophytic animals in an understorey shrub Piper cenocladum (Piperaceae). Predators and resource availability had significant direct and indirect effects on the diversity of the endophytic animal community, but the effects were not interactive, nor were they consistent between living vs. detrital food webs. The addition of fourth trophic level beetle predators increased diversity of consumers supported by living plant tissue, whereas balanced plant resources (light and nutrients) increased the diversity of primary through tertiary consumers in the detrital resources food web. These results support the hypotheses that top-down and bottom-up diversity cascades occur in terrestrial systems, and that diversity is affected by different factors in living vs. detrital food webs. [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] 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] Mining fuzzy quantitative association rulesEXPERT SYSTEMS, Issue 4 2006R.B.V. Subramanyam Abstract: The concept of fuzzy sets is one of the most fundamental and influential tools in the development of computational intelligence. In this paper the fuzzy pincer search algorithm is proposed. It generates fuzzy association rules by adopting combined top-down and bottom-up approaches. A fuzzy grid representation is used to reduce the number of scans of the database and our algorithm trims down the number of candidate fuzzy grids at each level. It has been observed that fuzzy association rules provide more realistic visualization of the knowledge extracted from databases. [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] 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] International Organizations in Transfer of Infectious Diseases: Iterative Loops of Adoption, Adaptation, and MarketingGOVERNANCE, Issue 2 2004Gill Walt Over the past few years increasing attention has been given to the role of international organizations in the diffusion of policy ideas and promotion of particular macro-level policies. Much of the attention has been on the ideological driving forces behind such policies, and on the extent to which the policies are externally imposed. There has been limited discussion on the bread-and-butter, technical policies of international organizations, and how they devise, adopt, adapt, and then promote what come to be seen as policies of global "best practice." This paper seeks to redress this gap by looking at the process of transfer of two infectious disease policies between international and national levels. It demonstrates that international organizations play different roles in policy transfer at particular stages in the process. The paper suggests that health policy transfer is a long adaptive process, made up of several iterative loops, as research and clinical practices developed in one or more countries are adopted, adapted, and taken up by international organizations which then mobilize support for particular policies, market, and promote them. Assumptions that new ideas about policies flow "rationally" into existing decision making are challenged by the processes analyzed here. Policy transfer, given the experience of these infectious diseases policies, goes through separate, "bottom-up," research-oriented, and "top-down" marketing-oriented loops. Individuals and different configurations of networks play key roles linking these loops. In the process, complex, context-specific policies are repackaged into simplified guidelines for global best practice, leading to considerable contestation within the policy networks. [source] FROM REVOLUTION TO MODERNIZATION: THE PARADIGMATIC TRANSITION IN CHINESE HISTORIOGRAPHY IN THE REFORM ERAHISTORY AND THEORY, Issue 3 2010HUAIYIN LI ABSTRACT Chinese historiography of modern China in the 1980s and 1990s underwent a paradigmatic transition: in place of the traditional revolutionary historiography that bases its analyses on Marxist methodologies and highlights rebellions and revolutions as the overarching themes in modern Chinese history, the emerging modernization paradigm builds its conceptual framework on borrowed modernization theory and foregrounds top-down, incremental reforms as the main force propelling China's evolution to modernity. This article scrutinizes the origins of the new paradigm in the context of a burgeoning modernization discourse in reform-era China. It further examines the fundamental divides between the two types of historiography in their respective constructions of master narratives and their different approaches to representing historical events in modern China. Behind the prevalence of the modernization paradigm in Chinese historiography is Chinese historians' unchanged commitment to serving present political needs by interpreting the past. [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] Legal Reform, Women's Empowerment and Social Change: The Case of EgyptIDS BULLETIN, Issue 2 2010Mulki Al-Sharmani In the last decade, new family laws have been passed in Egypt, with important ramifications for women. In this article, I argue that two issues diminish the transformative role that these reforms could play in strengthening Egyptian women's rights and achieving gender justice. First, despite the recently passed laws, the model of marriage that the state continues to uphold through its codes and courts is premised on gendered roles and rights for husbands and wives. This model, however, contradicts the realities of Egyptian marriages. Second, the incongruence between the agendas of different reform actors, their piecemeal approach, and their top-down and non-participatory strategies have impacted the reform outcomes in mixed ways. This has meant that the multidimensionality and the social-embeddedness of the process of law-making have not been adequately taken into account in the efforts undertaken by reform actors, thereby undermining the effectiveness and significance of these endeavours. [source] Urban community in China: service, participation and developmentINTERNATIONAL JOURNAL OF SOCIAL WELFARE, Issue 3 2006Qingwen Xu With the rapid urbanisation and population growth in the cities, the People's Republic of China has recognised the importance of community development based on an ever-increasing demand for social services. In 1994, the Chinese government adopted community service as an alternative way of providing the supplemental safety net in urban areas. Along with this top-down approach, resident-initiated activities, participation and grassroots organisations at the community level are growing at an incredible pace. Using a case study, this study explores the context and aspects of community services, participation and community development in a Chinese urban community. Results indicate that China's reformed market economy and welfare system presses ordinary urban people to reconnect to the local community to ensure welfare security and quality of life. Community participation in China has rediscovered the path of community development and re-interpreted the top-down and bottom-up approaches in the context of community services. [source] Participation in Urban Contention and DeliberationINTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 3 2010HILARY SILVER Abstract Participation is a popular buzzword in contemporary urban studies. For some, it implies a deepening of democratic deliberation; for others, it represents grassroots resistance to powerful elites and neoliberalization. Rather than seeing participation as either consensus-building or conflicts of interest, as either a top-down or bottom-up process, the evidence suggests that it can be all of these. By adopting a more dynamic, pragmatic, and empirically informed perspective, seemingly opposite normative conceptions of democratic participation may be theorized as different ,moments' in the democratic process. Bottom-up mobilization may coincide with and complement top-down initiatives, each dominating different political phases of policymaking, implementation and monitoring. Case studies from Belfast, Berlin, Durban, Philadelphia and São Paulo illustrate the approach and provide insight into the urban as a social laboratory in which other scales of social life and multiple ways to perform democracy are constructed. Résumé La participation est un terme qui revient très souvent dans les études urbaines contemporaines. Pour certains, elle implique une réflexion démocratique approfondie, pour d'autres, une résistance des citoyens face à la puissance des élites et au néolibéralisme. Si la participation peut être vue comme un moyen de bâtir des consensus ou l'expression de conflits d'intérêts, ou comme un processus imposé par le haut ou bien par la base, les faits suggèrent qu'elle peut être tout cela. En adoptant une perspective pragmatique plus dynamique reposant sur des éléments empiriques, des concepts normatifs de la participation apparemment opposés sont susceptibles d'être formulés en tant que "moments" différents du processus démocratique. La mobilisation par la base peut venir en coïncidence et complément d'initiatives imposées par le haut, chaque forme dominant des phases politiques distinctes dans la prise de décision, la mise en ,uvre et le suivi. Des études de cas portant sur Belfast, Berlin, Durban, Philadelphie et São Paulo illustrent la démarche et font apparaître l'urbain comme un laboratoire où s'élaborent d'autres dimensions de la vie sociale et de multiples modalités d'exercice de la démocratie. [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] Cascading top-down effects of changing oceanic predator abundancesJOURNAL OF ANIMAL ECOLOGY, Issue 4 2009Julia K. Baum Summary 1Top-down control can be an important determinant of ecosystem structure and function, but in oceanic ecosystems, where cascading effects of predator depletions, recoveries, and invasions could be significant, such effects had rarely been demonstrated until recently. 2Here we synthesize the evidence for oceanic top-down control that has emerged over the last decade, focusing on large, high trophic-level predators inhabiting continental shelves, seas, and the open ocean. 3In these ecosystems, where controlled manipulations are largely infeasible, ,pseudo-experimental' analyses of predator,prey interactions that treat independent predator populations as ,replicates', and temporal or spatial contrasts in predator populations and climate as ,treatments', are increasingly employed to help disentangle predator effects from environmental variation and noise. 4Substantial reductions in marine mammals, sharks, and piscivorous fishes have led to mesopredator and invertebrate predator increases. Conversely, abundant oceanic predators have suppressed prey abundances. Predation has also inhibited recovery of depleted species, sometimes through predator,prey role reversals. Trophic cascades have been initiated by oceanic predators linking to neritic food webs, but seem inconsistent in the pelagic realm with effects often attenuating at plankton. 5Top-down control is not uniformly strong in the ocean, and appears contingent on the intensity and nature of perturbations to predator abundances. Predator diversity may dampen cascading effects except where nonselective fisheries deplete entire predator functional groups. In other cases, simultaneous exploitation of predator and prey can inhibit prey responses. Explicit consideration of anthropogenic modifications to oceanic foodwebs should help inform predictions about trophic control. 6Synthesis and applications. Oceanic top-down control can have important socio-economic, conservation, and management implications as mesopredators and invertebrates assume dominance, and recovery of overexploited predators is impaired. Continued research aimed at integrating across trophic levels is needed to understand and forecast the ecosystem effects of changing oceanic predator abundances, the relative strength of top-down and bottom-up control, and interactions with intensifying anthropogenic stressors such as climate change. [source] Large-scale ecology and hydrology: an introductory perspective from the editors of the Journal of Applied EcologyJOURNAL OF APPLIED ECOLOGY, Issue 2000S.J. Ormerod 1. Five key features characterize large-scale factors in ecology: (a) they incorporate some of the most major of all ecological phenomena , the ranges of organisms, patterns of diversity, variations in ecosystem character and environmental processes such as climate, biogeochemical cycles, dispersal and migration; (b) they involve interactions across scales through both top-down and bottom-up processes; (c) they are multifaceted, and hence require an interdisciplinary perspective; (d) they reflect the cumulative effects of anthropogenic change across all scales, and so have direct relevance to environmental management; (e) they invariably exceed the range of classical ecological experiments, and so require alternative approaches to hypothesis testing. 2. Against this background, a recent research initiative on large-scale ecology and hydrology was funded jointly by the Natural Environment Research Council (NERC) and the Scottish Executive Rural Affairs Department (SERAD). Outputs from this programme are reported in this special issue of the Journal of Applied Ecology, and they illustrate some of the ecological research that is currently in progress in the UK at large spatio-temporal scales. 3. The spatial scales investigated in the papers range from hectares to whole continents, and much of the work reported here involves modelling. Although the model outputs are intrinsically valuable, several authors express the need for improved validation and testing. We suggest that this is an area requiring much development, and will need considerable innovation due to the difficulties at the scales involved (see 1d). Possible methods include: model applications to new circumstances; large-scale environmental manipulations; large-scale surveys that mimic experimental protocols; support from process studies at smaller scales. These alternatives are not mutually exclusive, and all can allow robust hypothesis testing. 4. Much of the work reported here is interdisciplinary linking, for example, geographical, mathematical, hydrological, hydrochemical and ecological concepts (see 1c). We suggest that even stronger links between environmental disciplines will further aid large-scale ecological research. 5. Most important in the context of the Journal of Applied Ecology, the work reported in this issue reveals that large-scale ecology already has applied value. Sectors benefiting include the conservation of biodiversity, the control of invasive species, and the management of land and water resources. 6. Large-scale issues continue to affect many applied ecologists, with roughly 30,40% of papers published in the Journal of Applied Ecology typically confronting such problems. This special issue adds to the growing body of seminal contributions that will add impetus to further large-scale work. Moreover, occurring in a period when other areas of biology are increasingly reductionist, this collection illustrates that, at least with respect to large-scale environmental problems, ecology still holds centre ground. [source] Fighting governmental corruption: the New World Bank programme evaluatedJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 4 2004Carolien M. Klein Haarhuis Over the past decade, the international donor community has come up with a range of initiatives to curb governmental corruption in developing countries. Top-down approaches devise administrative and judicial reforms, whereas bottom-up approaches deal with the process of awareness,raising in civil society. The World Bank currently integrates these top-down and bottom-up approaches in a combined anti-corruption programme. In this paper, the most recent version of this World Bank's training programme is reconstructed and assessed. Several core approaches in the programme, such as the strengthening of civil society and the privatisation of parastatals, turn out to have unintended consequences. The empirical support is largely case-specific and turns out to be highly conditional. It is concluded that indicators need to be developed to assess the relevance of national anti-corruption policies to country-specific governance and anti-corruption conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source] Beyond top-down and bottom-up work redesign: Customizing job content through idiosyncratic dealsJOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 2-3 2010Severin Hornung Two established approaches to work redesign are formal top-down interventions and proactive bottom-up job crafting. Top-down approaches are limited in their ability to create individually optimized work characteristics, whereas bottom-up processes are constrained by the latitude workers have to modify their own jobs. Following recent research on the idiosyncratic deals (i-deals) individuals negotiate with their employer, task i-deals customizing job content are suggested as a third approach to work redesign. Hypotheses on antecedents and consequences of task i-deals were tested in two studies conducted in the United States and Germany using structural equation modeling. LMX related positively to the extent of successfully negotiated task i-deals, which, in turn, was associated with a more positive evaluation of work characteristics,specifically, higher complexity and control and lower stressors. Work characteristics mediated positive indirect effects of task i-deals on employee initiative and work engagement. Denied requests for task i-deals were associated with a more negative assessment of work characteristics. We conclude with theoretical, practical, and research implications for better understanding and implementing work redesign through i-deals. Copyright © 2010 John Wiley & Sons, Ltd. 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