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Major Drivers (major + drivers)
Selected AbstractsReducing redundancy in invasion ecology by integrating hypotheses into a single theoretical frameworkDIVERSITY AND DISTRIBUTIONS, Issue 1 2009Jane A. Catford ABSTRACT Aim, Invasion ecology includes many hypotheses. Empirical evidence suggests that most of these can explain the success of some invaders to some degree in some circumstances. If they all are correct, what does this tell us about invasion? We illustrate the major themes in invasion ecology, and provide an overarching framework that helps organize research and foster links among subfields of invasion ecology and ecology more generally. Location, Global. Methods, We review and synthesize 29 leading hypotheses in plant invasion ecology. Structured around propagule pressure (P), abiotic characteristics (A) and biotic characteristics (B), with the additional influence of humans (H) on P, A and B (hereon PAB), we show how these hypotheses fit into one paradigm. P is based on the size and frequency of introductions, A incorporates ecosystem invasibility based on physical conditions, and B includes the characteristics of invading species (invasiveness), the recipient community and their interactions. Having justified the PAB framework, we propose a way in which invasion research could progress. Results, By highlighting the common ground among hypotheses, we show that invasion ecology is encumbered by theoretical redundancy that can be removed through integration. Using both holistic and incremental approaches, we show how the PAB framework can guide research and quantify the relative importance of different invasion mechanisms. Main conclusions, If the prime aim is to identify the main cause of invasion success, we contend that a top-down approach that focuses on PAB maximizes research efficiency. This approach identifies the most influential factors first, and subsequently narrows the number of potential causal mechanisms. By viewing invasion as a multifaceted process that can be partitioned into major drivers and broken down into a series of sequential steps, invasion theory can be rigorously tested, understanding improved and effective weed management techniques identified. [source] CRAS-CBR: Internal control risk assessment system using case-based reasoningEXPERT SYSTEMS, Issue 1 2004Sung-Sik Hwang Abstract: Information technology and the Internet have been major drivers for changes in all aspects of business processes and activities. They have brought major changes to the financial statements audit environment as well, which in turn has required modifications in audit procedures. There exist certain difficulties, however, with current audit procedures especially for the assessment of the level of control risk. This assessment is primarily based on the auditors' professional judgment and experiences, not on objective rules or criteria. To overcome these difficulties, we propose a prototype decision support model named CRAS-CBR using case-based reasoning to support auditors in making their professional judgment on the assessment of the level of control risk of the general accounting system in the manufacturing industry. To validate the performance, we compare our proposed model with benchmark performances in terms of classification accuracy for the level of control risk. Our experimental results show that CRAS-CBR outperforms a statistical model and staff auditor performance in average hit ratio. [source] Multiple stressors and regime shifts in shallow aquatic ecosystems in antipodean landscapesFRESHWATER BIOLOGY, Issue 2010JENNY DAVIS Summary 1. Changes in land management (land use and land cover) and water management (including extraction of ground water and diversion of surface waters for irrigation) driven by increases in agricultural production and urban expansion (and fundamentally by population growth) have created multiple stressors on global freshwater ecosystems that we can no longer ignore. 2. The development and testing of conceptual ecological models that examine the impact of stressors on aquatic ecosystems, and recognise that responses may be nonlinear, is now essential for identifying critical processes and predicting changes, particularly the possibility of catastrophic regime shifts or ,ecological surprises'. 3. Models depicting gradual ecological change and three types of regime shift (simple thresholds, hysteresis and irreversible changes) were examined in the context of shallow inland aquatic ecosystems (wetlands, shallow lakes and temporary river pools) in southwestern Australia subject to multiple anthropogenic impacts (hydrological change, eutrophication, salinisation and acidification). 4. Changes in hydrological processes, particularly the balance between groundwater-dominated versus surface water-dominated inputs and a change from seasonal to permanent water regimes appeared to be the major drivers influencing ecological regime change and the impacts of eutrophication and acidification (in urban systems) and salinisation and acidification (in agricultural systems). 5. In the absence of hydrological change, urban wetlands undergoing eutrophication and agricultural wetlands experiencing salinisation appeared to fit threshold models. Models encompassing alternative regimes and hysteresis appeared to be applicable where a change from a seasonal to permanent hydrological regime had occurred. 6. Irreversible ecological change has potentially occurred in agricultural landscapes because the external economic driver, agricultural productivity, persists independently of the impact on aquatic ecosystems. 7. Thematic implications: multiple stressors can create multiple thresholds that may act in a hierarchical fashion in shallow, lentic systems. The resulting regime shifts may follow different models and trajectories of recovery. Challenges for ecosystem managers and researchers include determining how close a system may be to critical thresholds and which processes are essential to maintaining or restoring the system. This requires an understanding of both external drivers and internal ecosystem dynamics, and the interactions between them, at appropriate spatial and temporal scales. [source] Regionalisation of chemical variability in European mountain lakesFRESHWATER BIOLOGY, Issue 12 2009LLUÍS CAMARERO Summary 1. We carried out a coordinated survey of mountain lakes covering the main ranges across Europe (including Greenland), sampling 379 lakes above the local tree line in 2000. The objectives were to identify the main sources of chemical variability in mountain lakes, define a chemical classification of lakes, and develop tools to extrapolate our results to regional lake populations through an empirical regionalisation or upscaling of chemical properties. 2. We investigated the main causes of chemical variability using factor analysis (FA) and empirical relationships between chemistry and several environmental variables. Weathering, sea salt inputs, atmospheric deposition of N and S, and biological activity in soils of the catchment were identified as the major drivers of lake chemistry. 3. We tested discriminant analysis (DA) to predict the lake chemistry. It was possible to use the lithology of the catchments to predict the range of Ca2+ and SO42, into which a lake of unknown chemistry will decrease. Lakes with lower SO42, concentrations have little geologically derived S, and better reflect the variations in atmospheric S loading. The influence of marine aerosols on lakewater chemistry could also be predicted from the minimum distance to the sea and altitude of the lakes. 4. The most remarkable result of FA was to reveal a factor correlated to DOC (positively) and NO3, (negatively). This inverse relationship might be the result either of independent processes active in the catchment soils and acting in an opposite sense, or a direct interaction, e.g. limitation of denitrification by DOC availability. Such a relationship has been reported in the recent literature in many sites and at all scales, appearing to be a global pattern that could reflect the link between the C and N cycles. 5. The concentration of NO3, is determined by both atmospheric N deposition and the processing capacity of the catchments (i.e. N uptake by plants and soil microbes). The fraction of the variability in NO3, because of atmospheric deposition is captured by an independent factor in the FA. This is the only factor showing a clear pattern when mapped over Europe, indicating lower N deposition in the northernmost areas. 6. A classification has been derived which takes into account all the major chemical features of the mountain lakes in Europe. FA provided the criteria to establish the most important factors influencing lake water chemistry, define classes within them, and classify the surveyed lakes into each class. DA can be used as a tool to scale up the classification to unsurveyed lakes, regarding sensitivity to acidification, marine influence and sources of S. [source] Exploitation and habitat degradation as agents of change within coral reef fish communitiesGLOBAL CHANGE BIOLOGY, Issue 12 2008S. K. WILSON Abstract Over-exploitation and habitat degradation are the two major drivers of global environmental change and are responsible for local extinctions and declining ecosystem services. Here we compare the top-down effect of exploitation by fishing with the bottom-up influence of habitat loss on fish communities in the most diverse of ecological systems, coral reefs. Using a combination of multivariate techniques and path analyses, we illustrate that the relative importance of coral cover and fishing in controlling fish abundance on remote Fijian reefs varies between species and functional groups. A decline in branching Acropora coral is strongly associated with a decline in abundance of coral-feeding species, and a decrease in coral-associated habitat complexity, which has indirectly contributed to reduced abundance of small-bodied damselfish. In contrast, reduced fishing pressure, brought about by declining human populations and a shift to alternate livelihoods, is associated with increased abundance of some piscivores and fisheries target species. However, availability of prey is controlled by coral-associated habitat complexity and appears to be a more important driver of total piscivore abundance compared with fishing pressure. Effects of both fishing and coral loss are stronger on individual species than functional groups, as variation in the relative importance of fishing or coral loss among species within the same functional group attenuated the impact of either of these potential drivers at the functional level. Overall, fishing continues to have an influence on Fijian fish communities; however, habitat loss is currently the overriding agent of change. The importance of coral loss mediated by climate change is expected to have an increasing contribution to fish community dynamics, particularly in remote locations or where the influence of fishing is waning. [source] Consumers' views on generic medicines: A review of the literatureINTERNATIONAL JOURNAL OF PHARMACY PRACTICE, Issue 2 2009Mohamed A. A. Hassali Abstract Objectives To review the literature on consumers' knowledge, attitudes and opinions of the use of generic medicines. Method A narrative review of studies conducted from 1970 to 2008 on consumers' perceptions and views towards generic medicines was performed. An extensive literature search was undertaken using indexing services available at the authors' institution library. The following keywords were used for the search: brand, generic, multisource, medications, medicines, drugs, pharmaceuticals and consumers, customers, and patients. Electronic databases searched were Medline, Inside Web, ISI Web of Knowledge, Science Direct, Springer Link, JSTOR, Proquest, Ebsco Host and Google Scholar. These electronic databases were searched for full text papers published in English from 1970 to October 2008. Key findings Twenty studies were identified. Eleven were from the USA, four were from Europe, two were from Canada and one each was from Australia, Brazil and Malaysia. In general, consumers showed mixed reactions towards the use of generic medicines. This was evident from the divergence of views observed by country development level, consumers' socioeconomic characteristics, drug product characteristics, pharmaceutical reimbursement system, policy environment, contact with health care professionals, past experience with medications, and knowledge of the seriousness of a medical condition. Conclusions Patient confidence and knowledge pertaining to generic medicines use have increased over the past four decades, especially in developed countries. Mass educational efforts, financial incentives, and greater communication among patients and health care professionals were seen as major drivers to the uptake of generic medicines among consumers. [source] Corporate training and development policies and practices: a cross-national study of India and BritainINTERNATIONAL JOURNAL OF TRAINING AND DEVELOPMENT, Issue 2 2003P.S. Yadapadithaya The aim of this paper is to report on the existing corporate training and development (T&D) policies and practices in India and Britain. The data were collected from written questionnaires mailed to 252 Indian and 174 British companies. The results and discussions are based on the most prominent comparative and international dimensions of T&D such as key responsibility for T&D function, corporate commitment to T&D, major drivers and key result areas of T&D; purposes, levels, instruments, timing, and designs of evaluation; major perceived deficiencies and challenges of T&D function. The two-country comparisons revealed that while some of the findings related to corporate T&D policies and practices exhibited differences, others also reflected similarity. Compared with India, more training is done in Britain, more movement to delegating responsibilities or involving line managers in T&D in Britain, there seems also to be more focus on and involvement of individual employees in Britain. British organisations seem to be more concerned with business results from T&D. It may also be argued that the greater importance attached to business results brings about a growing involvement of employees and managers as opposed to HRD practitioners and that it is the greater movement in this direction in Britain compared with India that accounts for most if not all of the differences in the results of the two surveys. [source] Evaluating Corporate Training and Development: An Indian ExperienceINTERNATIONAL JOURNAL OF TRAINING AND DEVELOPMENT, Issue 4 2001P. S. Yadapadithaya The central purpose of this article is to report on the current practices of evaluating training and development programs in the Indian corporate sector. The data were collected from written questionnaires mailed to 252 respondent companies,127 private, 99 public, and 26 multinational corporations (MNCs). The results and discussions are based on the major drivers and key result areas of training and development; purposes, levels, instruments, timing, and designs of evaluation; serious limitations of the training system; and finally the major challenges currently faced by the Indian corporate sector in strengthening the training and development function. [source] Assessing the impact of deforestation and climate change on the range size and environmental niche of bird species in the Atlantic forests, BrazilJOURNAL OF BIOGEOGRAPHY, Issue 7 2010Bette A. Loiselle Abstract Aim, Habitat loss and climate change are two major drivers of biological diversity. Here we quantify how deforestation has already changed, and how future climate scenarios may change, environmental conditions within the highly disturbed Atlantic forests of Brazil. We also examine how environmental conditions have been altered within the range of selected bird species. Location, Atlantic forests of south-eastern Brazil. Methods, The historical distribution of 21 bird species was estimated using Maxent. After superimposing the present-day forest cover, we examined the environmental niches hypothesized to be occupied by these birds pre- and post-deforestation using environmental niche factor analysis (ENFA). ENFA was also used to compare conditions in the entire Atlantic forest ecosystem pre- and post-deforestation. The relative influence of land use and climate change on environmental conditions was examined using analysis of similarity and principal components analysis. Results, Deforestation in the region has resulted in a decrease in suitable habitat of between 78% and 93% for the Atlantic forest birds included here. Further, Atlantic forest birds today experience generally wetter and less seasonal forest environments than they did historically. Models of future environmental conditions within forest remnants suggest generally warmer conditions and lower annual variation in rainfall due to greater precipitation in the driest quarter of the year. We found that deforestation resulted in a greater divergence of environmental conditions within Atlantic forests than that predicted by climate change. Main conclusions, The changes in environmental conditions that have occurred with large-scale deforestation suggest that selective regimes may have shifted and, as a consequence, spatial patterns of intra-specific variation in morphology, behaviour and genes have probably been altered. Although the observed shifts in available environmental conditions resulting from deforestation are greater than those predicted by climate change, the latter will result in novel environments that exceed temperatures in any present-day climates and may lead to biotic attrition unless organisms can adapt to these warmer conditions. Conserving intra-specific diversity over the long term will require considering both how changes in the recent past have influenced contemporary populations and the impact of future environmental change. [source] Influence of plant species and soil conditions on plant,soil feedback in mixed grassland communitiesJOURNAL OF ECOLOGY, Issue 2 2010Kathryn A. Harrison Summary 1.,Our aim was to explore plant,soil feedback in mixed grassland communities and its significance for plant productivity and community composition relative to abiotic factors of soil type and fertility. 2.,We carried out a 4-year, field-based mesocosm experiment to determine the relative effects of soil type, historic management intensity and soil conditioning by a wide range of plant species of mesotrophic grassland on the productivity and evenness of subsequent mixed communities. 3.,The study consisted of an initial soil conditioning phase, whereby soil from two locations each with two levels of management intensity was conditioned with monocultures of nine grassland species, and a subsequent feedback phase, where mixed communities of the nine species were grown in conditioned soil to determine relative effects of experimental factors on the productivity and evenness of mixed communities and individual plant species performance. 4.,In the conditioning phase of the experiment, individual plant species differentially influenced soil microbial communities and nutrient availability. However, these biotic effects were much less important as drivers of soil microbial properties and nutrient availability than were abiotic factors of soil type and fertility. 5.,Significant feedback effects of conditioning were detected during the second phase of the study in terms of individual plant growth in mixed communities. These feedback effects were generally independent of soil type or fertility, and were consistently negative in nature. In most cases, individual plant species performed less well in mixed communities planted in soil that had previously supported their own species. 6.,Synthesis. These findings suggest that despite soil abiotic factors acting as major drivers of soil microbial communities and nutrient availability, biotic interactions in the form of negative feedback play a significant role in regulating individual plant performance in mixed grassland communities across a range of soil conditions. [source] Landmarks in the understanding and treatment of reflux diseaseJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 2009John Dent Abstract The last 50 years have seen a transformation in the understanding and treatment of reflux disease. The development and wide use of flexible endoscopy and progressively more sophisticated approaches to measurement of pathophysiological factors have been major drivers of advances. The recognition and progressive elucidation of the mechanical events that comprise the transient lower esophageal sphincter relaxation and how they lead to reflux provide a novel and firm foundation for tailoring therapies that act directly to reduce occurrence of reflux episodes, either surgically or pharmacologically. Novel GABAB agonist drugs have been shown to inhibit transient relaxations and are currently being evaluated in clinical trials on patients with reflux disease. Better understanding has extended to recognition of the extraordinarily high prevalence of reflux disease and of the ability of proton pump inhibitor drugs to deliver major benefits to a high proportion of patients with reflux disease. The life of the Gastroenterological Society of Australia has spanned the period of these major advances. A large number of the members of the Society and their associates have contributed substantially to these advances. [source] Sunscreens: expectation and realizationPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2009Brian Diffey Background: The technical performance of sunscreens has improved dramatically over the past 20 years, so have we now succeeded in delivering protection that meets consumers' expectations? Methods: From a public health perspective, the desire to prevent sunburn and protect against skin cancer are the two major drivers for using sunscreen. This review examines how well consumers can expect to realize these expectations. Results: Sunscreens are used regularly by a minority of people, even during recreational summer exposure. The failure of sunscreen to prevent sunburn is almost always due to the way that sunscreens are applied rather than technical failure of the product. The mismatch between the labelled protection (sun protection factor) and that delivered in practice is a contributory factor to this ,failure'. Sunscreens have been shown to be effective in reducing the incidence of squamous cell cancer and with promising benefits for basal cell cancer. However, the evidence that they are effective in melanoma remains lacking. Conclusion: The formulation and extinction of sunscreens have undoubtedly improved over recent years. Yet the notion that sunscreens provide unequivocal protection against the deleterious effects of sun exposure by everyone who uses them remains elusive. [source] Martin K. Starr: A Visionary Proponent for System Integration, Modular Production, and Catastrophe AvoidancePRODUCTION AND OPERATIONS MANAGEMENT, Issue 1 2007Sushil Gupta Martin K. Starr facilitated the creation of an identity for production and operations management (POM) as an academic discipline. This paper aims to summarize Starr's substantial contributions to scholarly inquiry on system integration and interfunctional coordination, modular production, and catastrophe avoidance. Even after four decades, we describe how his legacy in these areas continues to define several major drivers of operations and supply chain management research and practice. Starr has influenced several generations of students, professors, and executives with his writings, teaching, and leadership roles in the POM community that include 32 years on the faculty of the Columbia School of Business, 15 years as Editor-in-Chief of Management Science, and presidency of the Production and Operations Management Society. [source] Land crabs as key drivers in tropical coastal forest recruitmentBIOLOGICAL REVIEWS, Issue 2 2009Erin Stewart Lindquist ABSTRACT Plant populations are regulated by a diverse assortment of abiotic and biotic factors that influence seed dispersal and viability, and seedling establishment and growth at the microsite. Rarely does one animal guild exert as significant an influence on different plant assemblages as land crabs. We review three tropical coastal ecosystems,mangroves, island maritime forests, and mainland coastal terrestrial forests,where land crabs directly influence forest composition by limiting tree establishment and recruitment. Land crabs differentially prey on seeds, propagules and seedlings along nutrient, chemical and physical environmental gradients. In all of these ecosystems, but especially mangroves, abiotic gradients are well studied, strong and influence plant species distributions. However, we suggest that crab predation has primacy over many of these environmental factors by acting as the first limiting factor of tropical tree recruitment to drive the potential structural and compositional organisation of coastal forests. We show that the influence of crabs varies relative to tidal gradient, shoreline distance, canopy position, time, season, tree species and fruiting periodicity. Crabs also facilitate forest growth and development through such activities as excavation of burrows, creation of soil mounds, aeration of soils, removal of leaf litter into burrows and creation of carbon-rich soil microhabitats. For all three systems, land crabs influence the distribution, density and size-class structure of tree populations. Indeed, crabs are among the major drivers of tree recruitment in tropical coastal forest ecosystems, and their conservation should be included in management plans of these forests. [source] | ||||||||||||||||