46 resultados para multiple change-points
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Aquatic ecosystems are confronted with multiple stress factors. Current approaches to assess the risk of anthropogenic stressors to aquatic ecosystems are developed for single stressors and determine stressor effects primarily as a function of stressor properties. The cumulative impact of several stressors, however, may differ markedly from the impact of the single stressors and can result in nonlinear effects and ecological surprises. To meet the challenge of diagnosing and predicting multiple stressor impacts, assessment strategies should focus on properties of the biological receptors rather than on stressor properties. This change of paradigm is required because (i) multiple stressors affect multiple biological targets at multiple organizational levels, (ii) biological receptors differ in their sensitivities, vulnerabilities, and response dynamics to the individual stressors, and (iii) biological receptors function as networks, so that actions of stressors at disparate sites within the network can lead via indirect or cascading effects, to unexpected outcomes.
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Purpose The purpose of this study was to investigate multiple indirect Big Five personality influences on professionals’ annual salary while considering relevant mediators. These are the motivational variables of occupational self-efficacy and career-advancement goals, and the work status variable of contractual work hours. The motivational and work status variables were conceptualized as serial mediators (Big Five → occupational self-efficacy/career-advancement goals → contractual work hours → annual salary). Design/Methodology/Approach We realized a 4 year longitudinal survey study with 432 participants and three points of measurement. We assessed personality prior to the mediators and the mediators prior to annual salary. Findings Results showed that except for openness the other Big Five personality traits exerted indirect influences on annual salary. Career-advancement goals mediated influences of conscientiousness (+), extraversion (+), and agreeableness (−). Occupational self-efficacy mediated influences of neuroticism (–) and conscientiousness (+). Because the influence of occupational self-efficacy on annual salary was fully mediated by contractual work hours, indirect personality influences via occupational self-efficacy always included contractual work hours in a serial mediation. Implications These findings underline the importance of distal personality traits for career success. They give further insights into direct and indirect relationships between personality, goal content, self-efficacy beliefs, and an individual’s career progress. Originality/Value Previous research predominantly investigated direct Big Five influences on salary, and it analyzed cross-sectional data. This study is one of the first to investigate multiple indirect Big Five influences on salary in a longitudinal design. The findings support process-oriented theories of personality influences on career outcomes.
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Species adapted to cold-climatic mountain environments are expected to face a high risk of range contractions, if not local extinctions under climate change. Yet, the populations of many endothermic species may not be primarily affected by physiological constraints, but indirectly by climate-induced changes of habitat characteristics. In mountain forests, where vertebrate species largely depend on vegetation composition and structure, deteriorating habitat suitability may thus be mitigated or even compensated by habitat management aiming at compositional and structural enhancement. We tested this possibility using four cold-adapted bird species with complementary habitat requirements as model organisms. Based on species data and environmental information collected in 300 1-km2 grid cells distributed across four mountain ranges in central Europe, we investigated (1) how species’ occurrence is explained by climate, landscape, and vegetation, (2) to what extent climate change and climate-induced vegetation changes will affect habitat suitability, and (3) whether these changes could be compensated by adaptive habitat management. Species presence was modelled as a function of climate, landscape and vegetation variables under current climate; moreover, vegetation-climate relationships were assessed. The models were extrapolated to the climatic conditions of 2050, assuming the moderate IPCC-scenario A1B, and changes in species’ occurrence probability were quantified. Finally, we assessed the maximum increase in occurrence probability that could be achieved by modifying one or multiple vegetation variables under altered climate conditions. Climate variables contributed significantly to explaining species occurrence, and expected climatic changes, as well as climate-induced vegetation trends, decreased the occurrence probability of all four species, particularly at the low-altitudinal margins of their distribution. These effects could be partly compensated by modifying single vegetation factors, but full compensation would only be achieved if several factors were changed in concert. The results illustrate the possibilities and limitations of adaptive species conservation management under climate change.
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An experiment was conducted to determine the effect of grazing versus zero-grazing on energy expenditure (EE), feeding behaviour and physical activity in dairy cows at different stages of lactation. Fourteen Holstein cows were subjected to two treatments in a repeated crossover design with three experimental series (S1, S2, and S3) reflecting increased days in milk (DIM). At the beginning of each series, cows were on average at 38, 94 and 171 (standard deviation (SD) 10.8) DIM, respectively. Each series consisted of two periods containing a 7-d adaptation and a 7-d collection period each. Cows either grazed on pasture for 16–18.5 h per day or were kept in a freestall barn and had ad libitum access to herbage harvested from the same paddock. Herbage intake was estimated using the double alkane technique. On each day of the collection period, EE of one cow in the barn and of one cow on pasture was determined for 6 h by using the 13C bicarbonate dilution technique, with blood sample collection done either manually in the barn or using an automatic sampling system on pasture. Furthermore, during each collection period physical activity and feeding behaviour of cows were recorded over 3 d using pedometers and behaviour recorders. Milk yield decreased with increasing DIM (P<0.001) but was similar with both treatments. Herbage intake was lower (P<0.01) for grazing cows (16.8 kg dry matter (DM)/d) compared to zero-grazing cows (18.9 kg DM/d). The lowest (P<0.001) intake was observed in S1 and similar intakes were observed in S2 and S3. Within the 6-h measurement period, grazing cows expended 19% more (P<0.001) energy (319 versus 269 kJ/kg metabolic body size (BW0.75)) than zero-grazing cows and differences in EE did not change with increasing DIM. Grazing cows spent proportionally more (P<0.001) time walking and less time standing (P<0.001) and lying (P<0.05) than zero-grazing cows. The proportion of time spent eating was greater (P<0.001) and that of time spent ruminating was lower (P<0.05) for grazing cows compared to zero-grazing cows. In conclusion, lower feed intake along with the unchanged milk production indicates that grazing cows mobilized body reserves to cover additional energy requirements which were at least partly caused by more physical activity. However, changes in cows׳ behaviour between the considered time points during lactation were too small so that differences in EE remained similar between treatments with increasing DIM.
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Urban agriculture is a phenomenon that can be observed world-wide, particularly in cities of devel-oping countries. It is contributing significantly to food security and food safety and has sustained livelihood of the urban and peri-urban low income dwellers in developing countries for many years. Population increase due to rural-urban migration and natural, coupled with formal as well as infor-mal urbanization are competing with urban farming for available space and scarce water resources. A multitemporal multisensoral urban change analysis over the period of 25 years (1982-2007) was performed in order to measure and visualize the urban expansion along the Kizinga and Mzinga valley in the South of Dar es Salaam. Airphotos and VHR satellite data were analyzed by using a combination of a composition of anisotropic textural measures and spectral information. The study revealed that unplanned built-up area is expanding continuously and vegetation covers and agricultural lands decline at a fast rate. The validation showed that the overall classification accuracy varied depending on the database. The extracted built-up areas were used for visual in-terpretation mapping purposes and served as information source for another research project. The maps visualize an urban congestion and expansion of nearly 18% of the total analyzed area that had taken place in the Kizinga valley between 1982 and 2007. The same development can be ob-served in the less developed and more remote Mzinga valley between 1981 and 2002. Both areas underwent fast changes where land prices still tend to go up and an influx of people both from rural and urban areas continuously increase density with the consequence of increasing multiple land use interests.
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Land-use intensification is a key driver of biodiversity change. However, little is known about how it alters relationships between the diversities of different taxonomic groups, which are often correlated due to shared environmental drivers and trophic interactions. Using data from 150 grassland sites, we examined how land-use intensification (increased fertilization, higher livestock densities, and increased mowing frequency) altered correlations between the species richness of 15 plant, invertebrate, and vertebrate taxa. We found that 54% of pairwise correlations between taxonomic groups were significant and positive among all grasslands, while only one was negative. Higher land-use intensity substantially weakened these correlations (35% decrease in r and 43% fewer significant pairwise correlations at high intensity), a pattern which may emerge as a result of biodiversity declines and the breakdown of specialized relationships in these conditions. Nevertheless, some groups (Coleoptera, Heteroptera, Hymenoptera and Orthoptera) were consistently correlated with multidiversity, an aggregate measure of total biodiversity comprised of the standardized diversities of multiple taxa, at both high and low land-use intensity. The form of intensification was also important; increased fertilization and mowing frequency typically weakened plant–plant and plant–primary consumer correlations, whereas grazing intensification did not. This may reflect decreased habitat heterogeneity under mowing and fertilization and increased habitat heterogeneity under grazing. While these results urge caution in using certain taxonomic groups to monitor impacts of agricultural management on biodiversity, they also suggest that the diversities of some groups are reasonably robust indicators of total biodiversity across a range of conditions. Read More: http://www.esajournals.org/doi/10.1890/14-1307.1
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The 5th Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) states with very high certainty that anthropogenic emissions have caused measurable changes in the physical ocean environment. These changes are summarized with special focus on those that are predicted to have the strongest, most direct effects on ocean biological processes; namely, ocean warming and associated phenomena (including stratification and sea level rise) as well as deoxygenation and ocean acidification. The biological effects of these changes are then discussed for microbes (including phytoplankton), plants, animals, warm and cold-water corals, and ecosystems. The IPCC AR5 highlighted several areas related to both the physical and biological processes that required further research. As a rapidly developing field, there have been many pertinent studies published since the cut off dates for the AR5, which have increased our understanding of the processes at work. This study undertook an extensive review of recently published literature to update the findings of the AR5 and provide a synthesized review on the main issues facing future oceans. The level of detail provided in the AR5 and subsequent work provided a basis for constructing projections of the state of ocean ecosystems in 2100 under two the Representative Concentration Pathways RCP4.5 and 8.5. Finally the review highlights notable additions, clarifications and points of departure from AR5 provided by subsequent studies.
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In sports games, it is often necessary to perceive a large number of moving objects (e.g., the ball and players). In this context, the role of peripheral vision for processing motion information in the periphery is often discussed especially when motor responses are required. In an attempt to test the basal functionality of peripheral vision in those sports-games situations, a Multiple Object Tracking (MOT) task that requires to track a certain number of targets amidst distractors, was chosen. Participants’ primary task was to recall four targets (out of 10 rectangular stimuli) after six seconds of quasi-random motion. As a second task, a button had to be pressed if a target change occurred (Exp 1: stop vs. form change to a diamond for 0.5 s; Exp 2: stop vs. slowdown for 0.5 s). While eccentricities of changes (5-10° vs. 15-20°) were manipulated, decision accuracy (recall and button press correct), motor response time as well as saccadic reaction time were calculated as dependent variables. Results show that participants indeed used peripheral vision to detect changes, because either no or very late saccades to the changed target were executed in correct trials. Moreover, a saccade was more often executed when eccentricities were small. Response accuracies were higher and response times were lower in the stop conditions of both experiments while larger eccentricities led to higher response times in all conditions. Summing up, it could be shown that monitoring targets and detecting changes can be processed by peripheral vision only and that a monitoring strategy on the basis of peripheral vision may be the optimal one as saccades may be afflicted with certain costs. Further research is planned to address the question whether this functionality is also evident in sports tasks.
Resumo:
In sports games, it is often necessary to perceive a large number of moving objects (e.g., the ball and players). In this context, the role of peripheral vision for processing motion information in the periphery is often discussed especially when motor responses are required. In an attempt to test the capability of using peripheral vision in those sports-games situations, a Multiple-Object-Tracking task that requires to track a certain number of targets amidst distractors, was chosen to determine the sensitivity of detecting target changes with peripheral vision only. Participants’ primary task was to recall four targets (out of 10 rectangular stimuli) after six seconds of quasi-random motion. As a second task, a button had to be pressed if a target change occurred (Exp 1: stop vs. form change to a diamond for 0.5 s; Exp 2: stop vs. slowdown for 0.5 s). Eccentricities of changes (5-10° vs. 15-20°) were manipulated, decision accuracy (recall and button press correct), motor response time and saccadic reaction time (change onset to saccade onset) were calculated and eye-movements were recorded. Results show that participants indeed used peripheral vision to detect changes, because either no or very late saccades to the changed target were executed in correct trials. Moreover, a saccade was more often executed when eccentricities were small. Response accuracies were higher and response times were lower in the stop conditions of both experiments while larger eccentricities led to higher response times in all conditions. Summing up, it could be shown that monitoring targets and detecting changes can be processed by peripheral vision only and that a monitoring strategy on the basis of peripheral vision may be the optimal one as saccades may be afflicted with certain costs. Further research is planned to address the question whether this functionality is also evident in sports tasks.
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The main goals of this study were to identifythe alpine torrent catchments that are sensitive to climatic changes and to assess the robustness of the methods for the elaboration of flood and debris flow hazard zone maps to specific effects of climate changes. In this study, a procedure for the identification and localization of torrent catchments in which the climate scenarios will modify the hazard situation was developed. In two case studies, the impacts of a potential increase of precipitation intensities to the delimited hazard zones were studied. The identification and localization of the torrent and river catchments, where unfavourable changes in the hazard situation occur, could eliminate speculative and unnecessary measures against the impacts of climate changes like a general enlargement of hazard zones or a general over dimensioning of protection structures for the whole territory. The results showed a high spatial variability of the sensitivity of catchments to climate changes. In sensitive catchments, the sediment management in alpine torrents will meet future challenges due to a higher rate for sediment removal from retention basins. The case studies showed a remarkable increase of the areas affected by floods and debris flow when considering possible future precipitation intensities in hazard mapping. But, the calculated increase in extent of future hazard zones lay within the uncertainty of the methods used today for the delimitation of the hazard zones. Thus, the consideration of the uncertainties laying in the methods for the elaboration of hazard zone maps in the torrent and river catchments sensitive to climate changes would provide a useful instrument for the consideration of potential future climate conditions. The study demonstrated that weak points in protection structures in future will become more important in risk management activities.
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The Younger Dryas cooling event disrupted the overall warming trend in the North Atlantic region during the last deglaciation. Climate change during the Younger Dryas was abrupt and thus provides insights into the sensitivity of the climate system to perturbations. The sudden Younger Dryas cooling has traditionally been attributed to a shutdown of the Atlantic Meridional Overturning Circulation by meltwater discharges. However, alternative explanations such as strong negative radiative forcing14 and a shift in atmospheric circulation have also been offered. Here we investigate the importance of these different forcings in coupled climate model experiments constrained by data assimilation. We find that the Younger Dryas climate signal as registered in proxy evidence is best simulated using a combination of processes: a weakened Atlantic Meridional Overturning Circulation, moderate negative radiative forcing and an altered atmospheric circulation. We conclude that none of the individual mechanisms alone provide a plausible explanation for the Younger Dryas cold period. We suggest that the triggers for abrupt climate changes such as the Younger Dryas are more complex than suggested so far, and that studies on the response of the climate system to perturbations should account for this complexity.
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More than 40 years after the agrarian reform, Peru is experiencing a renewed process of concentration of land ownership in the hands of large-scale investors, favoring the development of a sugar cane production cluster along the northern coast. The expansion of the agricultural frontier by means of large irrigation projects – originally developed to benefit medium- and small-scale farmers – is carried out today in order to be sold to large-scale investors for the production of export crops. In the region of Piura the increasing presence of large-scale biofuel investors puts substantial pressure on land and water resources, not only changing the use of and access to land for local communities, but also generating water shortages vis-à-vis the multiple water demands of local food producers. The changes in land relations and the agro-ecosystem, the altering food production regime as well as the increasing proletarization of smallholders, is driving many locals – even those which (initially) welcomed the investment – into resistance activities against the increasing control of land, water and other natural resources in the hands of agribusinesses. The aim of this presentation is to discuss the contemporary political, social and cultural dynamics of agrarian change along the northern Peruvian coast as well as the «reactions from below» emanating from campesino communities, landless laborers, brick producers, pastoralists as well as other marginalized groups. The different strategies, forms and practices of resistance with the goal of the «protection of the territory» shall be explored as well as the reasons for their rather scattered occurrence and the lack of alliances on the land issue. This input shall make a contribution to the on-going debate on individual and communal property rights and the question of what is best in terms of collective defense against land grabbing.
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The number of well-dated pollen diagrams in Europe has increased considerably over the last 30 years and many of them have been submitted to the European Pollen Database (EPD). This allows for the construction of increasingly precise maps of Holocene vegetation change across the continent. Chronological information in the EPD has been expressed in uncalibrated radiocarbon years, and most chronologies to date are based on this time scale. Here we present new chronologies for most of the datasets stored in the EPD based on calibrated radiocarbon years. Age information associated with pollen diagrams is often derived from the pollen stratigraphy itself or from other sedimentological information. We reviewed these chronological tie points and assigned uncertainties to them. The steps taken to generate the new chronologies are described and the rationale for a new classification system for age uncertainties is introduced. The resulting chronologies are fit for most continental-scale questions. They may not provide the best age model for particular sites, but may be viewed as general purpose chronologies. Taxonomic particularities of the data stored in the EPD are explained. An example is given of how the database can be queried to select samples with appropriate age control as well as the suitable taxonomic level to answer a specific research question.
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Synopsis: Sport organisations are facing multiple challenges originating from an increasingly complex and dynamic environment in general, and from internal changes in particular. Our study seeks to reveal and analyse the causes for professionalization processes in international sport federations, the forms resulting from it, as well as related consequences. Abstract: AIM OF ABSTRACT/PAPER - RESEARCH QUESTION Sport organisations are facing multiple challenges originating from an increasingly complex and dynamic environment in general, and from internal changes in particular. In this context, professionalization seems to have been adopted by sport organisations as an appropriate strategy to respond to pressures such as becoming more “business-like”. The ongoing study seeks to reveal and analyse the internal and external causes for professionalization processes in international sport federations, the forms resulting from it (e.g. organisational, managerial, economic) as well as related consequences on objectives, values, governance methods, performance management or again rationalisation. THEORETICAL BACKGROUND/LITERATURE REVIEW Studies on sport as specific non-profit sector mainly focus on the prospect of the “professionalization of individuals” (Thibault, Slack & Hinings, 1991), often within sport clubs (Thiel, Meier & Cachay, 2006) and national sport federations (Seippel, 2002) or on organisational change (Griginov & Sandanski, 2008; Slack & Hinings, 1987, 1992; Slack, 1985, 2001), thus leaving broader analysis on governance, management and professionalization in sport organisations an unaccomplished task. In order to further current research on above-mentioned topics, our intention is to analyse causes, forms and consequences of professionalisation processes in international sport federations. The social theory of action (Coleman, 1986; Esser, 1993) has been defined as appropriate theoretical framework, deriving in the following a multi-level framework for the analysis of sport organisations (Nagel, 2007). In light of the multi-level framework, sport federations are conceptualised as corporative actors whose objectives are defined and implemented with regard to the interests of member organisations (Heinemann, 2004) and/or other pressure groups. In order to understand social acting and social structures (Giddens 1984) of sport federations, two levels are in the focus of our analysis: the macro level examining the environment at large (political, social, economic systems etc.) and the meso level (Esser, 1999) examining organisational structures, actions and decisions of the federation’s headquarter as well as member organisations. METHODOLOGY, RESEARCH DESIGN AND DATA ANALYSIS The multi-level framework mentioned seeks to gather and analyse information on causes, forms and consequences of professionalization processes in sport federations. It is applied in a twofold approach: first an exploratory study based on nine semi-structured interviews with experts from umbrella sport organisations (IOC, WADA, ASOIF, AIOWF, etc.) as well as the analysis of related documents, relevant reports (IOC report 2000 on governance reform, Agenda 2020, etc.) and important moments of change in the Olympic Movement (Olympic revenue share, IOC evaluation criteria, etc.); and secondly several case studies. Whereas the exploratory study seeks more the causes for professionalization on an external, internal and headquarter level as depicted in the literature, the case studies rather focus on forms and consequences. Applying our conceptual framework, the analysis of forms is built around three dimensions: 1) Individuals (persons and positions), 2) Processes, structures (formalisation, specialisation), 3) Activities (strategic planning). With regard to consequences, we centre our attention on expectations of and relationships with stakeholders (e.g. cooperation with business partners), structure, culture and processes (e.g. governance models, performance), and expectations of and relationships with member organisations (e.g. centralisation vs. regionalisation). For the case studies, a mixed-method approach is applied to collect relevant data: questionnaires for rather quantitative data, interviews for rather qualitative data, as well as document and observatory analysis. RESULTS, DISCUSSION AND IMPLICATIONS/CONCLUSIONS With regard to causes of professionalization processes, we analyse the content of three different levels: 1. the external level, where the main pressure derives from financial resources (stakeholders, benefactors) and important turning points (scandals, media pressure, IOC requirements for Olympic sports); 2. the internal level, where pressure from member organisations turned out to be less decisive than assumed (little involvement of member organisations in decision-making); 3. the headquarter level, where specific economic models (World Cups, other international circuits, World Championships), and organisational structures (decision-making procedures, values, leadership) trigger or hinder a federation’s professionalization process. Based on our first analysis, an outline for an economic model is suggested, distinguishing four categories of IFs: “money-generating IFs” being rather based on commercialisation and strategic alliances; “classical Olympic IFs” being rather reactive and dependent on Olympic revenue; “classical non-Olympic IFs” being rather independent of the Olympic Movement; and “money-receiving IFs” being dependent on benefactors and having strong traditions and values. The results regarding forms and consequences will be outlined in the presentation. The first results from the two pilot studies will allow us to refine our conceptual framework for subsequent case studies, thus extending our data collection and developing fundamental conclusions. References: Bayle, E., & Robinson, L. (2007). A framework for understanding the performance of national governing bodies of sport. European Sport Management Quarterly, 7, 249–268 Chantelat, P. (2001). La professionnalisation des organisations sportives: Nouveaux débats, nouveaux enjeux [Professionalisation of sport organisations]. Paris: L’Harmattan. Dowling, M., Edwards, J., & Washington, M. (2014). Understanding the concept of professionalization in sport management research. Sport Management Review. Advance online publication. doi: 10.1016/j.smr.2014.02.003 Ferkins, L. & Shilbury, D. (2012). Good Boards Are Strategic: What Does That Mean for Sport Governance? Journal of Sport Management, 26, 67-80. Thibault, L., Slack, T., & Hinings, B. (1991). Professionalism, structures and systems: The impact of professional staff on voluntary sport organizations. International Review for the Sociology of Sport, 26, 83–97.
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In the current study it is investigated whether peripheral vision can be used to monitor multi-ple moving objects and to detect single-target changes. For this purpose, in Experiment 1, a modified MOT setup with a large projection and a constant-position centroid phase had to be checked first. Classical findings regarding the use of a virtual centroid to track multiple ob-jects and the dependency of tracking accuracy on target speed could be successfully replicat-ed. Thereafter, the main experimental variations regarding the manipulation of to-be-detected target changes could be introduced in Experiment 2. In addition to a button press used for the detection task, gaze behavior was assessed using an integrated eye-tracking system. The anal-ysis of saccadic reaction times in relation to the motor response shows that peripheral vision is naturally used to detect motion and form changes in MOT because the saccade to the target occurred after target-change offset. Furthermore, for changes of comparable task difficulties, motion changes are detected better by peripheral vision than form changes. Findings indicate that capabilities of the visual system (e.g., visual acuity) affect change detection rates and that covert-attention processes may be affected by vision-related aspects like spatial uncertainty. Moreover, it is argued that a centroid-MOT strategy might reduce the amount of saccade-related costs and that eye-tracking seems to be generally valuable to test predictions derived from theories on MOT. Finally, implications for testing covert attention in applied settings are proposed.