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Sample records for ecosystem limiting factor

  1. Nitrogen and phosphorus limitation over long-term ecosystem development in terrestrial ecosystems.

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    Duncan N L Menge

    Full Text Available Nutrient limitation to net primary production (NPP displays a diversity of patterns as ecosystems develop over a range of timescales. For example, some ecosystems transition from N limitation on young soils to P limitation on geologically old soils, whereas others appear to remain N limited. Under what conditions should N limitation and P limitation prevail? When do transitions between N and P limitation occur? We analyzed transient dynamics of multiple timescales in an ecosystem model to investigate these questions. Post-disturbance dynamics in our model are controlled by a cascade of rates, from plant uptake (very fast to litter turnover (fast to plant mortality (intermediate to plant-unavailable nutrient loss (slow to weathering (very slow. Young ecosystems are N limited when symbiotic N fixation (SNF is constrained and P weathering inputs are high relative to atmospheric N deposition and plant N:P demand, but P limited under opposite conditions. In the absence of SNF, N limitation is likely to worsen through succession (decades to centuries because P is mineralized faster than N. Over long timescales (centuries and longer this preferential P mineralization increases the N:P ratio of soil organic matter, leading to greater losses of plant-unavailable N versus P relative to plant N:P demand. These loss dynamics favor N limitation on older soils despite the rising organic matter N:P ratio. However, weathering depletion favors P limitation on older soils when continual P inputs (e.g., dust deposition are low, so nutrient limitation at the terminal equilibrium depends on the balance of these input and loss effects. If NPP switches from N to P limitation over long time periods, the transition time depends most strongly on the P weathering rate. At all timescales SNF has the capacity to overcome N limitation, so nutrient limitation depends critically on limits to SNF.

  2. Limits on carbon sequestration in arid blue carbon ecosystems.

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    Schile, Lisa M; Kauffman, J Boone; Crooks, Stephen; Fourqurean, James W; Glavan, Jane; Megonigal, J Patrick

    2017-04-01

    Coastal ecosystems produce and sequester significant amounts of carbon ("blue carbon"), which has been well documented in humid and semi-humid regions of temperate and tropical climates but less so in arid regions where mangroves, marshes, and seagrasses exist near the limit of their tolerance for extreme temperature and salinity. To better understand these unique systems, we measured whole-ecosystem carbon stocks in 58 sites across the United Arab Emirates (UAE) in natural and planted mangroves, salt marshes, seagrass beds, microbial mats, and coastal sabkha (inter- and supratidal unvegetated salt flats). Natural mangroves held significantly more carbon in above- and belowground biomass than other vegetated ecosystems. Planted mangrove carbon stocks increased with age, but there were large differences for sites of similar age. Soil carbon varied widely across sites (2-367 Mg C/ha), with ecosystem averages that ranged from 49 to 156 Mg C/ha. For the first time, microbial mats were documented to contain soil carbon pools comparable to vascular plant-dominated ecosystems, and could arguably be recognized as a unique blue carbon ecosystem. Total ecosystem carbon stocks ranged widely from 2 to 515 Mg C/ha (seagrass bed and mangrove, respectively). Seagrass beds had the lowest carbon stock per unit area, but the largest stock per total area due to their large spatial coverage. Compared to similar ecosystems globally, mangroves and marshes in the UAE have lower plant and soil carbon stocks; however, the difference in soil stocks is far larger than with plant stocks. This incongruent difference between stocks is likely due to poor carbon preservation under conditions of weakly reduced soils (200-350 mV), coarse-grained sediments, and active shoreline migration. This work represents the first attempt to produce a country-wide coastal ecosystem carbon accounting using a uniform sampling protocol, and was motivated by specific policy goals identified by the Abu Dhabi Global

  3. Metabolic models to investigate energy limited anaerobic ecosystems.

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    Rodríguez, J; Premier, G C; Guwy, A J; Dinsdale, R; Kleerebezem, R

    2009-01-01

    Anaerobic wastewater treatment is shifting from a philosophy of solely pollutants removal to a philosophy of combined resource recovery and waste treatment. Simultaneous wastewater treatment with energy recovery in the form of energy rich products, brings renewed interest to non-methanogenic anaerobic bioprocesses such as the anaerobic production of hydrogen, ethanol, solvents, VFAs, bioplastics and even electricity from microbial fuel cells. The existing kinetic-based modelling approaches, widely used in aerobic and methanogenic wastewater treatment processes, do not seem adequate in investigating such energy limited microbial ecosystems. The great diversity of similar microbial species, which share many of the fermentative reaction pathways, makes quantify microbial groups very difficult and causes identifiability problems. A modelling approach based on the consideration of metabolic reaction networks instead of on separated microbial groups is suggested as an alternative to describe anaerobic microbial ecosystems and in particular for the prediction of product formation as a function of environmental conditions imposed. The limited number of existing relevant fermentative pathways in conjunction with the fact that anaerobic reactions proceed very close to thermodynamic equilibrium reduces the complexity of such approach and the degrees of freedom in terms of product formation fluxes. In addition, energy limitation in these anaerobic microbial ecosystems makes plausible that selective forces associated with energy further define the system activity by favouring those conversions/microorganisms which provide the most energy for growth under the conditions imposed.

  4. Landscape genetics and limiting factors

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    Samuel A. Cushman; Andrew J. Shirk; Erin L. Landguth

    2013-01-01

    Population connectivity is mediated by the movement of organisms or propagules through landscapes. However, little is known about how variation in the pattern of landscape mosaics affects the detectability of landscape genetic relationships. The goal of this paper is to explore the impacts of limiting factors on landscape genetic processes using simulation...

  5. FACTORS THAT STIMULATE THE ECOSYSTEM ROMANIAN ENTREPRENEURIAL

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    ENEA CONSTANŢA

    2017-12-01

    Full Text Available Entrepreneurship has begun to grapple with the global economic and financial crisis, and entrepreneurs have become "heroes" capable of delivering impetus to fragile economies. Small and innovative companies account for 99% of all Europe's active companies and offer 66% of available jobs. In the context of a worrying unemployment rate that persists in many countries of the world, entrepreneurship has become a viable solution to economic problems. Entrepreneurship can not be defined precisely, and the multidimensionality and homogeneity of the concept makes it very difficult to generalize the conclusions of studies for regions other than those for which they were originally developed. The objective of the present study is to carry out a comprehensive analysis of the Romanian entrepreneurial ecosystem and the factors that have the power to stimulate it, thus allowing the design of efficient policies for the development of Romanian entrepreneurship.

  6. Does the Ecosystem Service Concept Reach its Limits in Urban Environments?

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    Simone A. Beichler

    2017-06-01

    Full Text Available There is a rapidly growing body of literature on the theory about the ecosystem service concept and the practical assessment of ecosystem services in different contexts ranging from natural to urban environments. Yet, where does the concept reach its limits? This paper critically reflects the application of the ecosystem service concept in urban environments illustrating the handling of urban structures (incl. built-up areas and the risk that the normative principle of the concept could be missed. It is shown that in theory urban structures refer to a variety of ecosystem concepts. As a starting point for ecosystem service assessments, these could be classified into natural, managed, constructed and overbuilt systems. Since ecosystem service concepts do not directly refer to a specific ecosystem definition, but to biophysical structures and processes, all of these classes could be included. However, the dependency on context and scale makes a differentiation in practical ecosystem services assessment challenging. We conclude that the ecosystem service concept does not reach its limits in urban environments, but urban environments represent an extreme case characterized by multifunctionality and a high degree of modification that enables to uncover research challenges applying in any environment. There is a need for a more transparent reporting of theoretical and methodological assumptions to facilitate the comparability between ecosystem service assessments. Comprehensive approaches that consider multiple ecosystem services and include human input, human modification, the ecosystem status as well as their interactions are required to understand the spatial relations between ecosystem services delivered by different ecosystems.

  7. Acid deposition in aquatic ecosystems: Setting limits empirically

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    Newcombe, Charles P.

    1985-07-01

    The problem of acid deposition and its harmful effects on aquatic ecosystems has created a new branch of science that is called upon to provide the knowledge on which legislative controls can be based. However, because of the nature of existing legislation, which requires evidence of cause and effect between industrial emissions and pollution, and because of science's inability to provide this information over the short term, considerable controversy has arisen about whether sufficient information exists to warrant control measures at this time. Among those who advocate controls, there is genuine divergence of opinion about how stringent the controls must be to achieve any desired level of protection. The controversy has led to an impasse between the scientific and political participants, which is reflected in the slow pace of progress toward an effective management strategy. Resolution of the impasse, at least in the short term, may demand that science and politics rely on empirical models rather than explanatory ones. The empirical model, which is the major proposal in this article, integrates all of the major variables and many of the minor ones, and constructs a three-dimensionally curved surface capable of representing the status of any waterbody subjected to the effects of acid deposition. When suitably calibrated—a process involving the integration of knowledge and data from aquatic biology, geochemistry, meteorology, and limnology—it can be used to depict limits to the rate of acid deposition required for any level of environmental protection. Because it can generate a pictorial display of the effects of management decisions and legislative controls, the model might serve as a basis for enhancing the quality of communication among all the scientific and political participants and help to resolve many of their controversies.

  8. On the Vulnerability of Water Limited Ecosystems to Climate Change

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    Kelly K. Caylor

    2013-06-01

    Full Text Available Society is facing growing environmental problems that require new research efforts to understand the way ecosystems operate and survive, and their mutual relationships with the hydrologic cycle. In this respect, ecohydrology suggests a renewed interdisciplinary approach that aims to provide a better comprehension of the effects of climatic changes on terrestrial ecosystems. With this aim, a coupled hydrological/ecological model is adopted to describe simultaneously vegetation pattern evolution and hydrological water budget at the basin scale using as test site the Upper Rio Salado basin (Sevilleta, NM, USA. The hydrological analyses have been carried out using a recently formulated framework for the water balance at the daily level linked with a spatial model for the description of the spatial organization of vegetation. This enables quantitatively assessing the effects on soil water availability on future climatic scenarios. Results highlighted that the relationship between climatic forcing (water availability and vegetation patterns is strongly non-linear. This implies, under some specific conditions which depend on the ecosystem characteristics, small changes in climatic conditions may produce significant transformation of the vegetation patterns.

  9. The Ecosystem Factor in Supporting Wiki Initiative for Knowledge Sharing in Malaysian Public Organisation

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    Khairil Hizar Md Khuzaimah

    2015-10-01

    Full Text Available The purpose of this paper is to highlight the significance of considering the organizational ecosystem in implementing wikis for knowledge sharing.The findings suggest that a prerequisite of an effective wiki is the appreciation of the factors that make up the organizational ecosystem; technical and organizational factors are variable elements of the ecosystem that can significantly impact the wiki; and the task of re-aligning an existing wiki taking into consideration these factors can be complex.The case study was based on knowledge sharing in a public project management organization, thereby limiting the generalizability to other organizations. Organizations which are keen to adopt wiki as part of their knowledge management initiative need to contextualize their wiki initiative within the organizational context.This research contributes to extending the knowledge-base of the factors that impact the effectiveness of wikis for knowledge sharing by linking the wiki to the broader organizational factors.

  10. Potential and limitations of inferring ecosystem photosynthetic capacity from leaf functional traits

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    Talie Musavi; Mirco Migliavacca; Martine Janet van de Weg; Jens Kattge; Georg Wohlfahrt; Peter M. van Bodegom; Markus Reichstein; Michael Bahn; Arnaud Carrara; Tomas F. Domingues; Michael Gavazzi; Damiano Gianelle; Cristina Gimeno; André Granier; Carsten Gruening; Kateřina Havránková; Mathias Herbst; Charmaine Hrynkiw; Aram Kalhori; Thomas Kaminski; Katja Klumpp; Pasi Kolari; Bernard Longdoz; Stefano Minerbi; Leonardo Montagnani; Eddy Moors; Walter C. Oechel; Peter B. Reich; Shani Rohatyn; Alessandra Rossi; Eyal Rotenberg; Andrej Varlagin; Matthew Wilkinson; Christian Wirth; Miguel D. Mahecha

    2016-01-01

    The aim of this study was to systematically analyze the potential and limitations of using plant functional trait observations from global databases versus in situ data to improve our understanding of vegetation impacts on ecosystem functional properties (EFPs). Using ecosystem photosynthetic capacity as an example, we first provide an objective approach to derive...

  11. Preliminary disposal limits, plume interaction factors, and final disposal limits

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2018-01-11

    In the 2008 E-Area Performance Assessment (PA), each final disposal limit was constructed as the product of a preliminary disposal limit and a plume interaction factor. The following mathematical development demonstrates that performance objectives are generally expected to be satisfied with high confidence under practical PA scenarios using this method. However, radionuclides that experience significant decay between a disposal unit and the 100-meter boundary, such as H-3 and Sr-90, can challenge performance objectives, depending on the disposed-of waste composition, facility geometry, and the significance of the plume interaction factor. Pros and cons of analyzing single disposal units or multiple disposal units as a group in the preliminary disposal limits analysis are also identified.

  12. Habitat, not resource availability, limits consumer production in lake ecosystems

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    Craig, Nicola; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

    2015-01-01

    Food web productivity in lakes can be limited by dissolved organic carbon (DOC), which reduces fish production by limiting the abundance of their zoobenthic prey. We demonstrate that in a set of 10 small, north temperate lakes spanning a wide DOC gradient, these negative effects of high DOC concentrations on zoobenthos production are driven primarily by availability of warm, well-oxygenated habitat, rather than by light limitation of benthic primary production as previously proposed. There was no significant effect of benthic primary production on zoobenthos production after controlling for oxygen, even though stable isotope analysis indicated that zoobenthos do use this resource. Mean whole-lake zoobenthos production was lower in high-DOC lakes with reduced availability of oxygenated habitat, as was fish biomass. These insights improve understanding of lake food webs and inform management in the face of spatial variability and ongoing temporal change in lake DOC concentrations.

  13. Limiting factors in caribou population ecology

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    David R. Klein

    1991-10-01

    Full Text Available Caribou and wild reindeer populations fluctuate over time. On this fact there is general agreement. Factors responsible for population limitation and subsequent declines have been examined within the framework of animal population theory. There is, however, little agreement when factors limiting specific populations are generalized to Rangifer populations over broad geographic regions. Comparative examinations of wild Rangifer populations worldwide discloses that factors that have regulated those populations are highly variable between populations, apparently as a reflection of the differences in environmental variables unique to each population. Examples exist of populations where major regulating factors have been climatic extremes, predation, hunting mortality, food limitation, insects, parasites, disease, interspecific competition, and human developmental impacts or combinations of these factors. This diversity of limiting factors affecting caribou and wild reindeer populations is a reflection of the ecologial complexity of the species, a concept that has often been ignored in past efforts to reach management decisions by extrapolation from the limited localized knowledge available on the species.

  14. Regional zooplankton biodiversity provides limited buffering of pond ecosystems against climate change.

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    Thompson, Patrick L; Shurin, Jonathan B

    2012-01-01

    1. Climate change and other human-driven environmental perturbations are causing reductions in biodiversity and impacting the functioning of ecosystems on a global scale. Metacommunity theory suggests that ecosystem connectivity may reduce the magnitude of these impacts if the regional species pool contains functionally redundant species that differ in their environmental tolerances. Dispersal may increase the resistance of local ecosystems to environmental stress by providing regional species with traits adapted to novel conditions. 2. We tested this theory by subjecting freshwater zooplankton communities in mesocosms that were either connected to or isolated from the larger regional species pool to a factorial manipulation of experimental warming and increased salinity. 3. Compensation by regional taxa depended on the source of stress. Warming tolerant regional taxa partially compensated for reductions in heat sensitive local taxa but similar compensation did not occur under increased salinity. 4. Dispersal-mediated species invasions dampened the effects of warming on summer net ecosystem productivity. However, this buffering effect did not occur in the fall or for periphyton growth, the only other ecosystem function affected by the stress treatments. 5. The results indicate that regional biodiversity can provide insurance in a dynamic environment but that the buffering capacity is limited to some ecosystem processes and sources of stress. Maintaining regional biodiversity and habitat connectivity may therefore provide some limited insurance for local ecosystems in changing environments, but is unable to impart resistance against all sources of environmental stress. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.

  15. Photodegradation of Leaf Litter in Water-Limited Ecosystems

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    Cory, R. M.; Powers, H.; McDowell, N.; Rahn, T.

    2008-12-01

    The longstanding view of terrestrial decomposition holds that heterotrophic respiration drives release of CO2, but recent studies, such as Austin and Vivanco (2006) have shown that in water-limited environments, photochemical decomposition of leaf litter may be equally or more effective than microbial decomposition. Although initial studies have concluded that photochemical degradation can be important in some environments, it has been difficult to quantify and the oxidative mechanisms involved remain unknown. Thus, the objectives of our study were to (1) quantify the CO2 emitted during photochemical degradation of leaf litter and (2) use the stable isotopic signatures of evolved CO2 to elucidate pathways of production. Emitted CO2 and its isotopic signature were measured using a tunable diode laser (TDL) to assess the pool of photochemically-labile plant matter (δ13C-CO2) in a given sample and to assess the source of the oxygen (δ18O-CO2). We quantified the photochemical release of CO2 and its isotopic signature from dried leaf litter of 10 tree and grass species prevalent in major biotic zones of New Mexico. The cumulative CO2 released upon exposure of 0.1-0.3 g of dried leaf litter to three hours of simulated sunlight ranged from 8-25 mg CO2-C g-1 dried litter, corresponding to 1-2% mass loss. Generally, the δ13C-CO2 was more depleted (4-7 ± 2 per mil) than the average δ13C of the respective leaf litter sample. The δ18O-CO2 evolved is approximately equal to δ18O of atmospheric O2, suggesting that the oxidation mechanism involves direct reaction with atmospheric O2.

  16. Setting limits: Using air pollution thresholds to protect and restore US ecosystems

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    Fenn, Mark E.; Lambert, Kathleen F.; Blett, Tamara F.; Burns, Douglas A.; Pardo, Linda H.; Lovett, Gary M.; Haeuber, Richard A.; Evers, David C.; Driscoll, Charles T.; Jeffries, Dean S.

    2011-01-01

    More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage.

  17. Ecosystem development in roadside grasslands: Biotic control, plant-soil interactions, and dispersal limitations

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    Garcia-Palacios, P.; Bowker, M.A.; Maestre, F.T.; Soliveres, S.; Valladares, F.; Papadopoulos, J.; Escudero, A.

    2011-01-01

    Roadside grasslands undergoing secondary succession are abundant, and represent ecologically meaningful examples of novel, human-created ecosystems. Interactions between plant and soil communities (hereafter plant-soil interactions) are of major importance in understanding the role of biotic control in ecosystem functioning, but little is known about these links in the context of ecosystem restoration and succession. The assessment of the key biotic communities and interactions driving ecosystem development will help practitioners to better allocate the limited resources devoted to roadside grassland restoration. We surveyed roadside grasslands from three successional stages (0-2, 7-9, and > 20 years) in two Mediterranean regions of Spain. Structural equation modeling was used to evaluate how interactions between plants, biological soil crusts (BSCs), and soil microbial functional diversity (soil microorganisms) affect indicators of ecosystem development and restoration: plant similarity to the reference ecosystem, erosion control, and soil C storage and N accumulation. Changes in plant community composition along the successional gradient exerted the strongest influence on these indicators. High BSC cover was associated with high soil stability, and high soil microbial functional diversity from late-successional stages was associated with high soil fertility. Contrary to our expectations, the indirect effects of plants, mediated by either BSCs or soil microorganisms, were very weak in both regions, suggesting a minor role for plant-soil interactions upon ecosystem development indicators over long periods. Our results suggest that natural vegetation dynamics effectively improved ecosystem development within a time frame of 20 years in the grasslands evaluated. They also indicate that this time could be shortened if management actions focus on: (1) maintaining wellconserved natural areas close to roadsides to enhance plant compositional changes towards late

  18. [Net photosynthesis and its affecting factors in a tropical seasonal rainforest ecosystem in southwest China].

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    Song, Qing-hai; Zhang, Yi-ping; Tan, Zheng-hong; Zhang, Lei-ming; Yang, Zhen; Zhao, Shuang-ju; Sun, Xiao-min

    2010-12-01

    By using eddy covariance technique, this paper quantitatively analyzed the photosynthetic characteristics of tropical seasonal rainforest ecosystem and related environmental controlling factors in Xishuangbanna in 2003-2006. In the study period, less interannual difference was observed in the net photosynthesis of the ecosystem, with the maximum photosynthesis rate (P(eco,opt)), respiration at daytime (R(eco,d)), and apparent quantum yield (alpha) averaged by 0.813 mg x m(-2) x s(-1), 0.238 mg x m(-2) x s(-1), and 0.0023 mg x micromol(-1), respectively. As affected by the interaction of air temperature (Ta) and vapor pressure deficit (VPD), the photosynthetic characteristics had some seasonal differences. In rainy season, the ecosystem had the strongest photosynthetic capacity because of the higher precipitation and warmer air temperature; in foggy and cool season, fog drip played an important role in the water relations of plants, and thereby, the ecosystem photosynthetic capacity was still higher; in dry and hot season, due to the limited precipitation and high temperature, the Ta and VPD increased, inducing a decrease of ecosystem alpha and P(eco,opt). The net CO2 exchange of the ecosystem strongly depended on the Ta above 20 degrees C and the VPD above 1 kPa.

  19. Ecosystem specific dose conversion factors for Aberg, Beberg and Ceberg

    International Nuclear Information System (INIS)

    Nordlinder, S.; Bergstroem, U.; Mathiasson, Lena

    1999-12-01

    The aim of this study was to calculate ecosystem specific dose conversion factors (EDFs) for three hypothetical sites, Aberg, Beberg and Ceberg, used in the safety analysis SR 97. The EDFs can, in combination with calculated releases of radionuclides from the geosphere, be used to illustrate relative differences in doses to the most exposed individual due to accidental leakage of radionuclides from a deep repository for spent nuclear fuel. Maps of the three sites were studied and subdivided into areas, which were characterised according to an earlier developed module system. For each of the identified modules, ecosystem transport and exposure model calculations were performed for release of 1 Bq per year during 10 000 years. 44 radionuclides contained within a deep repository for spent nuclear fuel were considered. A preliminary comparison of the EDFs for the three sites showed that the highest relative doses can be expected in Ceberg due to the high frequency of peat bog modules

  20. Aggregated filter-feeding consumers alter nutrient limitation: consequences for ecosystem and community dynamics.

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    Atkinson, Carla L; Vaughn, Caryn C; Forshay, Kenneth J; Cooper, Joshua T

    2013-06-01

    Nutrient cycling is a key process linking organisms in ecosystems. This is especially apparent in stream environments in which nutrients are taken up readily and cycled through the system in a downstream trajectory. Ecological stoichiometry predicts that biogeochemical cycles of different elements are interdependent because the organisms that drive these cycles require fixed ratios of nutrients. There is growing recognition that animals play an important role in biogeochemical cycling across ecosystems. In particular, dense aggregations of consumers can create biogeochemical hotspots in aquatic ecosystems via nutrient translocation. We predicted that filter-feeding freshwater mussels, which occur as speciose, high-biomass aggregates, would create biogeochemical hotspots in streams by altering nutrient limitation and algal dynamics. In a field study, we manipulated nitrogen and phosphorus using nutrient-diffusing substrates in areas with high and low mussel abundance, recorded algal growth and community composition, and determined in situ mussel excretion stoichiometry at 18 sites in three rivers (Kiamichi, Little, and Mountain Fork Rivers, south-central United States). Our results indicate that mussels greatly influence ecosystem processes by modifying the nutrients that limit primary productivity. Sites without mussels were N-limited with -26% higher relative abundances of N-fixing blue-green algae, while sites with high mussel densities were co-limited (N and P) and dominated by diatoms. These results corroborated the results of our excretion experiments; our path analysis indicated that mussel excretion has a strong influence on stream water column N:P. Due to the high N:P of mussel excretion, strict N-limitation was alleviated, and the system switched to being co-limited by both N and P. This shows that translocation of nutrients by mussel aggregations is important to nutrient dynamics and algal species composition in these rivers. Our study highlights the

  1. Factors influencing DOC leaching from terrestrial ecosystems: a database analysis

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    Camino Serrano, M.; Janssens, I.; Luyssaert, S.; Ciais, P.; Gielen, B.

    2012-04-01

    The lateral transport of dissolved organic carbon (DOC) is an important process linking terrestrial and aquatic ecosystems. Neglecting these fluxes can lead to biased of eddy covariance-based estimates of terrestrial ecosystem carbon sequestration. The necessity for integrating DOC leaching in carbon cycle models is thus clear, especially in view of future model development aiming at directly linking terrestrial, freshwater and ocean carbon cycles. However, to achieve this goal, more accurate information is needed in order to better understand and predict dissolved organic carbon dynamics. DOC concentrations mainly vary by geographical location, soil and vegetation types, topography, season and climate. Within this framework, we developed a database on DOC concentrations and fluxes with the aim of better understanding how those parameters determine DOC variations. This database compiles DOC concentrations and fluxes in soil solution and creeks at site or catchment level for different ecosystems around the world, but with special focus on the Northern Hemisphere and on peatland ecosystems. The database currently includes information from around 120 sites, gathered from published literature and datasets accessible on the internet. The database contains annual, seasonal and monthly data on DOC, dissolved inorganic carbon (DIC), dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) and also includes other meta-data related to the site, such as land cover, soil properties, climate, annual water balance and other soil solution parameters. This compiled dataset allows to study the influence of several physical factors that determine DOC production in soils. We will present the observed relationships between drivers, such as precipitation, drainage flows, soil pH, soil texture, and DOC concentration/ DOC fluxes at different levels, ecosystem types, temporal scales (monthly versus annual or seasonal), and soil depths. The same relations will be analysed

  2. Nutrient addition differentially affects ecological processes of Avicennia germinans in nitrogen versus phosphorus limited mangrove ecosystems

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    Feller, Ilka C.; Lovelock, C.E.; McKee, K.L.

    2007-01-01

    Nutrient over-enrichment is a major threat to marine environments, but system-specific attributes of coastal ecosystems may result in differences in their sensitivity and susceptibility to eutrophication. We used fertilization experiments in nitrogen (N)- and phosphorus (P)-limited mangrove forests to test the hypothesis that alleviating different kinds of nutrient limitation may have different effects on ecosystem structure and function in natural systems. We compared a broad range of ecological processes to determine if these systems have different thresholds where shifts might occur in nutrient limitation. Growth responses indicated N limitation in Avicennia germinans (black mangrove) forests in the Indian River Lagoon (IRL), Florida, and P limitation at Twin Cays, Belize. When nutrient deficiency was relieved, A. germinans grew out of its stunted form by increasing wood relative to leaf biomass and shoot length relative to lateral growth. At the P-limited site, P enrichment (+P) increased specific leaf area, N resorption, and P uptake, but had no effect on P resorption. At the N-limited site, +N increased both N and P resorption, but did not alter biomass allocation. Herbivory was greater at the P-limited site and was unaffected by +P, whereas +N led to increased herbivory at the N-limited site. The responses to nutrient enrichment depended on the ecological process and limiting nutrient and suggested that N- versus P-limited mangroves do have different thresholds. +P had a greater effect on more ecological processes at Twin Cays than did +N at the IRL, which indicated that the P-limited site was more sensitive to nutrient loading. Because of this sensitivity, eutrophication is more likely to cause a shift in nutrient limitation at P-limited Twin Cays than N-limited IRL. ?? 2007 Springer Science+Business Media, LLC.

  3. Global comparison reveals biogenic weathering as driven by nutrient limitation at ecosystem scale

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    Boy, Jens; Godoy, Roberto; Dechene, Annika; Shibistova, Olga; Amir, Hamid; Iskandar, Issi; Fogliano, Bruno; Boy, Diana; McCulloch, Robert; Andrino, Alberto; Gschwendtner, Silvia; Marin, Cesar; Sauheitl, Leopold; Dultz, Stefan; Mikutta, Robert; Guggenberger, Georg

    2017-04-01

    A substantial contribution of biogenic weathering in ecosystem nutrition, especially by symbiotic microorganisms, has often been proposed, but large-scale in vivo studies are still missing. Here we compare a set of ecosystems spanning from the Antarctic to tropical forests for their potential biogenic weathering and its drivers. To address biogenic weathering rates, we installed mineral mesocosms only accessible for bacteria and fungi for up to 4 years, which contained freshly broken and defined nutrient-baring minerals in soil A horizons of ecosystems along a gradient of soil development differing in climate and plant species communities. Alterations of the buried minerals were analyzed by grid-intersection, confocal lascer scanning microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy on the surface and on thin sections. On selected sites, carbon fluxes were tracked by 13C labeling, and microbial community was identified by DNA sequencing. In young ecosystems (protosoils) biogenic weathering is almost absent and starts after first carbon accumulation by aeolian (later litter) inputs and is mainly performed by bacteria. With ongoing soil development and appearance of symbiotic (mycorrhized) plants, nutrient availability in soil increasingly drove biogenic weathering, and fungi became the far more important players than bacteria. We found a close relation between fungal biogenic weathering and available potassium across all 16 forested sites in the study, regardless of the dominant mycorrhiza type (AM or EM), climate, and plant-species composition. We conclude that nutrient limitations at ecosystem scale are generally counteracted by adapted fungal biogenic weathering. The close relation between fungal weathering and plant-available nutrients over a large range of severely contrasting ecosystems points towards a direct energetic support of these weathering processes by the photoautotrophic community, making biogenic weathering a

  4. Nitrogen excess in North American ecosystems: Predisposing factors, ecosystem responses, and management strategies

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    Fenn, M.E.; Poth, M.A.; Aber, J.D.; Baron, Jill S.; Bormann, B.T.; Johnson, D.W.; Lemly, A.D.; McNulty, S.G.; Ryan, D.F.; Stottlemyer, R.

    1998-01-01

    Most forests in North America remain nitrogen limited, although recent studies have identified forested areas that exhibit symptoms of N excess, analogous to overfertilization of arable land. Nitrogen excess in watersheds is detrimental because of disruptions in plant/soil nutrient relations, increased soil acidification and aluminum mobility, increased emissions of nitrogenous greenhouse gases from soil, reduced methane consumption in soil, decreased water quality, toxic effects on freshwater biota, and eutrophication of coastal marine waters. Elevated nitrate (NO3/-) loss to groundwater or surface waters is the primary symptom of N excess. Additional symptoms include increasing N concentrations and higher N:nutrient ratios in foliage (i.e., N:Mg, N:P), foliar accumulation of amino acids or NO3/-, and low soil C:N ratios. Recent nitrogen-fertilization studies in New England and Europe provide preliminary evidence that some forests receiving chronic N inputs may decline in productivity and experience greater mortality. Long-term fertilization at Mount Ascutney, Vermont, suggests that declining and slow N-cycling coniferous stands may be replaced by fast-growing and fast N-cycling deciduous forests. Symptoms of N saturation are particularly severe in high-elevation, nonaggrading spruce-fir ecosystems in the Appalachian Mountains and in eastern hardwood watersheds at the Fernow Experimental Forest near Parsons, West Virginia. In the Los Angeles Air Basin, mixed conifer forests and chaparral watersheds with high smog exposure are N saturated and exhibit the highest streamwater NO3/- concentrations for wildlands in North America. High-elevation alpine watersheds in the Colorado Front Range and a deciduous forest in Ontario, Canada, are N saturated, although N deposition is moderate (~8 kg??ha-1??yr-1). In contrast, the Harvard Forest hardwood stand in Massachusetts has absorbed >900 kg N/ha during 8 yr of N amendment studies without significant NO3/- leaching

  5. Nucleon form factors. Probing the chiral limit

    International Nuclear Information System (INIS)

    Goeckeler, M.; Haegler, P.; Horsley, R.

    2006-10-01

    The electromagnetic form factors provide important hints for the internal structure of the nucleon and continue to be of major interest for experimentalists. For an intermediate range of momentum transfers the form factors can be calculated on the lattice. However, reliability of the results is limited by systematic errors due to the required extrapolation to physical quark masses. Chiral effective field theories predict a rather strong quark mass dependence in a range which was yet unaccessible for lattice simulations. We give an update on recent results from the QCDSF collaboration using gauge configurations with Nf=2, non-perturbatively O(a)-improved Wilson fermions at very small quark masses down to 340 MeV pion mass, where we start to probe the relevant quark mass region. (orig.)

  6. Simulation of population response to ionizing radiation in an ecosystem with a limiting resource--Model and analytical solutions.

    Science.gov (United States)

    Sazykina, Tatiana G; Kryshev, Alexander I

    2016-01-01

    A dynamic mathematical model is formulated, predicting the development of radiation effects in a generic animal population, inhabiting an elemental ecosystem 'population-limiting resource'. Differential equations of the model describe the dynamic responses to radiation damage of the following population characteristics: gross biomass; intrinsic fractions of healthy and reversibly damaged tissues in biomass; intrinsic concentrations of the self-repairing pool and the growth factor; and amount of the limiting resource available in the environment. Analytical formulae are found for the steady states of model variables as non-linear functions of the dose rate of chronic radiation exposure. Analytical solutions make it possible to predict the expected severity of radiation effects in a model ecosystem, including such endpoints as morbidity, mortality, life shortening, biosynthesis, and population biomass. Model parameters are selected from species data on lifespan, physiological growth and mortality rates, and individual radiosensitivity. Thresholds for population extinction can be analytically calculated for different animal species, examples are provided for generic mice and wolf populations. The ecosystem model demonstrates a compensatory effect of the environment on the development of radiation effects in wildlife. The model can be employed to construct a preliminary scale 'radiation exposure-population effects' for different animal species; species can be identified, which are vulnerable at a population level to chronic radiation exposure. Copyright © 2015. Published by Elsevier Ltd.

  7. Seasonal zooplankton dynamics in Lake Michigan: disentangling impacts of resource limitation, ecosystem engineering, and predation during a critical ecosystem transition

    Science.gov (United States)

    Vanderploeg, Henry A.; Pothoven, Steven A.; Fahnenstiel, Gary L.; Cavaletto, Joann F.; Liebig, James R.; Stow, Craig Stow; Nalepa, Thomas F.; Madenjian, Charles P.; Bunnell, David B.

    2012-01-01

    We examined seasonal dynamics of zooplankton at an offshore station in Lake Michigan from 1994 to 2003 and 2007 to 2008. This period saw variable weather, declines in planktivorous fish abundance, the introduction and expansion of dreissenid mussels, and a slow decline in total phosphorus concentrations. After the major expansion of mussels into deep water (2007–2008), chlorophyll in spring declined sharply, Secchi depth increased markedly in all seasons, and planktivorous fish biomass declined to record-low levels. Overlaying these dramatic ecosystem-level changes, the zooplankton community exhibited complex seasonal dynamics between 1994–2003 and 2007–2008. Phenology of the zooplankton maximum was affected by onset of thermal stratification, but there was no other discernable effect due to temperature. Interannual variability in zooplankton biomass during 1994 and 2003 was strongly driven by planktivorous fish abundance, particularly age-0 and age-1 alewives. In 2007–2008, there were large decreases in Diacyclops thomasi and Daphnia mendotae possibly caused by food limitation as well as increased predation and indirect negative effects from increases in Bythotrephes longimanus abundance and in foraging efficiency associated with increased light penetration. The Bythotrephes increase was likely driven in part by decreased predation from yearling and older alewife. While there was a major decrease in epilimnetic–metalimnetic herbivorous cladocerans in 2007–2008, there was an increase in large omnivorous and predacious calanoid copepods, especially those in the hypolimnion. Thus, changes to the zooplankton community are the result of cascading, synergistic interactions, including a shift from vertebrate to invertebrate planktivory and mussel ecosystem impacts on light climate and chlorophyll.

  8. Setting limits: Using air pollution thresholds to protect and restore U.S. ecosystems

    Science.gov (United States)

    Fenn, M.E.; Lambert, K.F.; Blett, T.F.; Burns, Douglas A.; Pardo, L.H.; Lovett, Gary M.; Haeuber, R. A.; Evers, D.C.; Driscoll, C.T.; Jeffries, D.S.

    2011-01-01

    More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage. Based on the results of a comprehensive review of air pollution thresholds, we conclude: ??? Ecosystem services such as air and water purification, decomposition and detoxification of waste materials, climate regulation, regeneration of soil fertility, production and biodiversity maintenance, as well as crop, timber and fish supplies are impacted by deposition of nitrogen, sulfur, mercury and other pollutants. The consequences of these changes may be difficult or impossible to reverse as impacts cascade throughout affected ecosystems. ??? The effects of too much nitrogen are common across the U.S. and include altered plant and lichen communities, enhanced growth of invasive species, eutrophication and acidification of lands and waters, and habitat deterioration for native species, including endangered species. ??? Lake, stream and soil acidification is widespread across the eastern United States. Up to 65% of lakes within sensitive areas receive acid deposition that exceeds critical loads. ??? Mercury contamination adversely affects fish in many inland and coastal waters. Fish consumption advisories for mercury exist in all 50

  9. Uranium - a factor limiting nuclear energy?

    International Nuclear Information System (INIS)

    Ohnemus, J.

    2006-01-01

    Nuclear power has been back as a topic of public debate since early this year. A special subject under discussion is the extension of nuclear power plant life. Hardly had it been on the agenda, when interested parties announced that this st ep was impossible because uranium reserves were no longer sufficient. A variety of terms are being used in this discussion without their meaning being taken int o account: stocks, resources, and reserves. To clarify the situation, this artic le outlines important aspects of short and long term uranium supplies, and analy zes their meaning. Here are some of the most important issues under consideration: - For what period of time is there really enough uranium? - Is uranium becoming the limiting factor in the use of nuclear power? - Is uranium really a 'sustainable' energy resource? - Will higher prices extend the range? - What is the in fluence of the price of uranium on the cost of electricity generation? Among oth er results, it is found that comprehensive sources of low-price uranium and nucl ear fuels are, or can be made, available worldwide. Consequently, the 'range' is beyond the time frames currently mentioned, also as a function of technological factors, i.e. reaching several hundred years. It is also important to note that nuclear power - ensures greater independence of volatile imported sources, - guarantees reliably low electricity prices, - has a huge potential of environmental protection, and - is a clean source of energy. (orig.)

  10. Uranium, a factor limiting nuclear energy?

    International Nuclear Information System (INIS)

    2006-01-01

    Nuclear power has been back as a topic of public debate since early this year. A special subject under discussion is the extension of nuclear power plant life. Hardly had it been on the agenda, when interested parties announced that this step was impossible because uranium reserves were no longer sufficient. A variety of terms are being used in this discussion without their meaning being taken into account: stocks, resources, and reserves. To clarify the situation, this article outlines important aspects of short and long term uranium supplies, and analyzes their meaning. Here are some of the most important issues under consideration: - For what period of time is there really enough uranium? - Is uranium becoming the limiting factor in the use of nuclear power? - Is uranium really a 'sustainable' energy resource? - Will higher prices extend the range? - What is the influence of the price of uranium on the cost of electricity generation? Among other results, it is found that comprehensive sources of low-price uranium and nuclear fuels are, or can be made, available worldwide. Consequently, the 'range' is beyond the time frames currently mentioned, also as a function of technological factors, i.e. reaching several hundred years. It is also important to note that nuclear power - ensures greater independence of volatile imported sources, - guarantees reliably low electricity prices, - has a huge potential of environmental protection, and - is a clean source of energy. (orig./GL)

  11. Simulation of population response to ionizing radiation in an ecosystem with a limiting resource – Model and analytical solutions

    International Nuclear Information System (INIS)

    Sazykina, Tatiana G.; Kryshev, Alexander I.

    2016-01-01

    A dynamic mathematical model is formulated, predicting the development of radiation effects in a generic animal population, inhabiting an elemental ecosystem ‘population-limiting resource’. Differential equations of the model describe the dynamic responses to radiation damage of the following population characteristics: gross biomass; intrinsic fractions of healthy and reversibly damaged tissues in biomass; intrinsic concentrations of the self-repairing pool and the growth factor; and amount of the limiting resource available in the environment. Analytical formulae are found for the steady states of model variables as non-linear functions of the dose rate of chronic radiation exposure. Analytical solutions make it possible to predict the expected severity of radiation effects in a model ecosystem, including such endpoints as morbidity, mortality, life shortening, biosynthesis, and population biomass. Model parameters are selected from species data on lifespan, physiological growth and mortality rates, and individual radiosensitivity. Thresholds for population extinction can be analytically calculated for different animal species, examples are provided for generic mice and wolf populations. The ecosystem model demonstrates a compensatory effect of the environment on the development of radiation effects in wildlife. The model can be employed to construct a preliminary scale ‘radiation exposure-population effects’ for different animal species; species can be identified, which are vulnerable at a population level to chronic radiation exposure. - Highlights: • Mathematical model is formulated predicting radiation effects in elemental ecosystem. • Analytical formulae are found for steady states of variables as functions of exposure. • Severity of radiation effects are calculated, including population extinction. • Model parameterization is made for generic mice and wolf populations.

  12. 14 CFR 23.337 - Limit maneuvering load factors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit maneuvering load factors. 23.337... Flight Loads § 23.337 Limit maneuvering load factors. (a) The positive limit maneuvering load factor n... airplanes; or (3) 6.0 for acrobatic category airplanes. (b) The negative limit maneuvering load factor may...

  13. Estimating annual rainfall threshold for establishment of tree species in water-limited ecosystems using tree-ring data

    NARCIS (Netherlands)

    Lopez, B.C.; Holmgren, M.; Sabate, S.; Gracia, C.A.

    2008-01-01

    In arid and semi-arid ecosystems, water availability is discontinuous, highly variable, and characterized by discrete pulse events separated by long periods of limited resource availability. Plant recruitment in these ecosystems is also episodic and dependent on the water available during and after

  14. Potential and limitations of inferring ecosystem photosynthetic capacity from leaf functional traits

    Czech Academy of Sciences Publication Activity Database

    Musavi, T.; Migliavacca, M.; van de Weg, M. J.; Kattge, J.; Wohlfahrt, G.; van Bodegom, P. M.; Reichstein, M.; Bahn, M.; Carrara, A.; Domingues, T. F.; Gavazzi, M.; Gianelle, D.; Gimeno, C.; Granier, A.; Gruening, C.; Havránková, Kateřina; Herbst, M.; Hrynkiw, Ch.; Kalhori, A.; Kaminski, T.; Klumpp, K.; Kolari, P.; Longdoz, B.; Minerbi, S.; Montagnani, L.; Moors, E.; Oechel, W.; Reich, P. B.; Rohatyn, S.; Rossi, A.; Rotenberg, E.; Varlagin, A.; Wilkinson, M.; Wirth, C.; Mahecha, M. D.

    2016-01-01

    Roč. 6, č. 20 (2016), s. 7352-7366 ISSN 2045-7758 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : gross primary production * cross-biome analysis * relative growth-rate * plant traits * carbon-dioxide * forest productivity * wide-range * environmental variation * nutrient concentrations * terrestrial biosphere * ecosystem functional property * eddy covariance * fluxnet * interannual variability * photosynthetic capacity * plant traits * spatiotemporal variability * TRY database Subject RIV: EH - Ecology, Behaviour Impact factor: 2.440, year: 2016

  15. Plant responses, climate pivot points, and trade-offs in water-limited ecosystems

    Science.gov (United States)

    Munson, Seth M.

    2013-01-01

    Plant species in dryland ecosystems are limited by water availability and may be vulnerable to increases in aridity. Methods are needed to monitor and assess the rate of change in plant abundance and composition in relation to climate, understand the potential for degradation in dryland ecosystems, and forecast future changes in plant species assemblages. I employ nearly a century of vegetation monitoring data from three North American deserts to demonstrate an approach to determine plant species responses to climate and critical points over a range of climatic conditions at which plant species shift from increases to decreases in abundance (climate pivot points). I assess these metrics from a site to regional scale and highlight how these indicators of plant performance can be modified by the physical and biotic environment. For example, shrubs were more responsive to drought and high temperatures on shallow soils with limited capacity to store water and fine-textured soils with slow percolation rates, whereas perennial grasses were more responsive to precipitation in sparse shrublands than in relatively dense grasslands and shrublands, where competition for water is likely more intense. The responses and associated climate pivot points of plant species aligned with their lifespan and structural characteristics, and the relationship between responses and climate pivot points provides evidence of the trade-off between the capacity of a plant species to increase in abundance when water is available and its drought resistance.

  16. The Role of Vegetation Dynamics on the Groundwater Recharge in a Water-Limited Ecosystem

    Science.gov (United States)

    Montaldo, N.; Mancini, M.; Albertson, J. D.; Katul, G.

    2003-04-01

    The structure and function of the vegetation regulates the exchange of mass, energy and momentum across the biosphere-atmosphere interface. Root systems affect soil properties, and vegetation density dominates the functioning of hydrological processes through modification of interception, infiltration, evapotranspiration, surface runoff, and groundwater recharge. Influencing the partitioning of incoming solar energy into sensible and latent heat fluxes, the changes in vegetation densities will result in long-term changes in both local and global climates (e.g., precipitation and temperature), and in turn will affect the vegetation growth as a feedback. In semi-arid regions, this may result in persistent drought and desertification, with substantial impacts on the human populations of these regions through reduction in agricultural productivity and reduction in quantity and quality of water supply. In these regions the water becomes a controlling factor, and the groundwater becomes an important water resource. We investigate the role of vegetation dynamics in the soil-vegetation-atmosphere system, and, in particular, on the groundwater recharge in a water-limited ecosystem. The questions addressed are: 1) how does groundwater recharge under grass differ from that under a tree canopy? 2) how does the recharge difference depend on the time scale over which precipitation variability or change occurs? 3) and, to what extent does “temporal change in leaf area” (i.e. denser vegetation in wetter periods) control the answers to the above questions? To reach the objectives, a coupled land surface model (LSM) and vegetation dynamics model is employed. The simple dynamic vegetation model simulates the plant growth, and provides the Leaf Area Index (LAI) evolution through time, which is then used by the LSM in the computation of the energy partitioning between soil and vegetation as well in the parameterization of turbulent transport and evapotranspiration. This updates the

  17. The Ecosystem Factor in Supporting Wiki Initiative for Knowledge Sharing in Malaysian Public Organisation

    Science.gov (United States)

    Khuzaimah, Khairil Hizar Md; Affandi, Haryanti Mohd; Hassan, Fadzil

    2015-01-01

    The purpose of this paper is to highlight the significance of considering the organizational ecosystem in implementing wikis for knowledge sharing.The findings suggest that a prerequisite of an effective wiki is the appreciation of the factors that make up the organizational ecosystem; technical and organizational factors are variable elements of…

  18. The Limits of Acclimation of land plants in a Terrestrial Ecosystems Model

    Science.gov (United States)

    Kothavala, Zavareh

    2014-05-01

    In this study, we examine the role of the terrestrial carbon cycle and the ability of different plant types to acclimate to a changing climate at the centennial scale using a global ecosystems model with updated biogeochemical processes related to moisture, carbon, and nitrogen. Elevated level of atmospheric carbon dioxide (CO2) increases CO2 fertilization, resulting in more CO2 uptake by vegetation, whereas the concomitant warming increases autotrophic and heterotrophic respiration, releasing CO2 to the atmosphere. Additionally, warming will enhance photosynthesis if current temperatures are below the optimal temperature for plant growth, while it will reduce photosynthesis if current temperatures are above the optimal temperature for plant growth. We present a series of ensemble simulations to evaluate the ability of plants to acclimate to changing conditions over the last century and how this affects the terrestrial carbon sink. A set of experiments related to (a) the varying relationship between CO2 fertilization and the half saturation constant, (b) the factors related to gross primary productivity and maintenance respiration, and (c) the variables related to heterotrophic respiration, were conducted with thirteen plant functional types. The experiments were performed using the Terrestrial Ecosystem Model (TEM) with a present-day vegetation distribution without the effects of natural or human disturbance, and a closed Nitrogen cycle, at a half-degree resolution over the globe. The experiment design consisted of eight scenarios that are consistent with past and future ecosystem conditions, presented in other scientific studies. The significance of model trends related to runoff, soil moisture, soil carbon, Net Primary Productivity (NPP), crop yield, and Net Ecosystem Productivity (NEP) for different seasons, as well as surface temperature, precipitation, vapor pressure, and photosynthetically active radiation are analyzed for various ecosystems at the global

  19. 14 CFR 25.337 - Limit maneuvering load factors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit maneuvering load factors. 25.337... Conditions § 25.337 Limit maneuvering load factors. (a) Except where limited by maximum (static) lift... maneuvering load factors prescribed in this section. Pitching velocities appropriate to the corresponding pull...

  20. Bioaccumulation factors in aquatic ecosystems. A critical review

    International Nuclear Information System (INIS)

    Karlsson, Sara; Meili, Markus; Bergstroem, Ulla

    2002-07-01

    The calculated concentrations of radionuclides in organisms are often obtained by means of bioaccumulation factors (BAF) that describe the internal concentration relative to an external concentration e.g. in the abiotic environments at steady-state conditions. Such factors are often used when modelling the dose to man from radio-nuclides released to the biosphere. Values of bioaccumulation factors vary widely in magnitude among elements, organisms, and environmental conditions which is not always considered. In order to relate the bioaccumulation factors for some radionuclides to environmental conditions as well as to the trophic level of the organism of concern we have compiled an extensive database with bioaccumulation factors (about 5,500 values) together with information on some environmental conditions. The data for nine radionuclides has been extracted and examined. A comparison between the bioaccumulation factors found in this study and values given in literature by IAEA and NCRP shows that the ranges presented in this study are generally somewhat higher with the exception of BAF for molybdenum in freshwater fish which is of the same order of magnitude. This is startling and calls for a thorough research. The amount of readily accessible and reliable values of BAF is limited, often because basic information such as e.g. units and part of organism examined, is not reported. This is surprising and also unfortunate for those who need such data for use in generic or specific models. A major update of recommended values appears to be necessary for many elements to account for the development of analytical methods and experiences from case studies over the past two decades

  1. Bioaccumulation factors in aquatic ecosystems. A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Sara; Meili, Markus; Bergstroem, Ulla [Studsvik Eco and Safety AB, Nykoeping (Sweden)

    2002-07-01

    The calculated concentrations of radionuclides in organisms are often obtained by means of bioaccumulation factors (BAF) that describe the internal concentration relative to an external concentration e.g. in the abiotic environments at steady-state conditions. Such factors are often used when modelling the dose to man from radio-nuclides released to the biosphere. Values of bioaccumulation factors vary widely in magnitude among elements, organisms, and environmental conditions which is not always considered. In order to relate the bioaccumulation factors for some radionuclides to environmental conditions as well as to the trophic level of the organism of concern we have compiled an extensive database with bioaccumulation factors (about 5,500 values) together with information on some environmental conditions. The data for nine radionuclides has been extracted and examined. A comparison between the bioaccumulation factors found in this study and values given in literature by IAEA and NCRP shows that the ranges presented in this study are generally somewhat higher with the exception of BAF for molybdenum in freshwater fish which is of the same order of magnitude. This is startling and calls for a thorough research. The amount of readily accessible and reliable values of BAF is limited, often because basic information such as e.g. units and part of organism examined, is not reported. This is surprising and also unfortunate for those who need such data for use in generic or specific models. A major update of recommended values appears to be necessary for many elements to account for the development of analytical methods and experiences from case studies over the past two decades.

  2. Springs as Model Systems for Aquatic Ecosystems Ecology: Stoichiometry, Metabolism and Nutrient Limitation

    Science.gov (United States)

    Cohen, M. J.; Nifong, R. L.; Kurz, M. J.; Martin, J. B.; Cropper, W. P.; Korhnak, L. V.

    2013-12-01

    Springs have been called nature's chemostats, where low variation in discharge, temperature and chemistry creates a natural laboratory in which to address basic questions about aquatic ecosystems. Ecological stoichiometry posits that patterns of metabolism, trophic energy transfer and community structure arise in response to coupled elemental cycles. In this work we synthesize several recent studies in Florida's iconic springs to explore the overarching hypothesis that stoichiometry can be used to indicate the nutrient limitation status of autotrophs and ecosystem metabolism. Of foremost importance is that the chemically stable conditions observed in springs ensures that autotroph tissue elemental composition, which is thought to vary with environmental supply, is near steady state. Moreover, the elemental ratios of discharging water vary dramatically across our study springs (for example, molar N:P ranges from 0.4:1 to 400:1), subjecting the communities of autotrophs, which are largely conserved across systems, to dramatically different nutrient supply. At the scale of whole ecosystem metabolism, we show that C:N:P ratios are strongly conserved across a wide gradient of environmental supplies, counter to the prediction of stoichiometric plasticity. Moreover, the absence of a relationship between gross primary production and nutrient concentrations or stoichiometry suggests that metabolic homeostasis may be a diagnostic symptom of nutrient saturation. At the scale of individual autotrophs, both submerged vascular plants and filamentous algae, this finding is strongly reinforced, with remarkable within-species tissue C:N:P homeostasis over large gradients, and no statistically significant evidence that gradients in nutrient supply affect autotroph composition. Expanding the suite of elements for which contemporaneous environment and tissue measurements are available to include 19 metals and micronutrients revealed that, while plants were homeostatic across large N

  3. Genetic transformation of barley: limiting factors

    Czech Academy of Sciences Publication Activity Database

    Vyroubalová, Š.; Šmehilová, M.; Galuszka, P.; Ohnoutková, Ludmila

    2011-01-01

    Roč. 55, č. 2 (2011), s. 213-224 ISSN 0006-3134 R&D Projects: GA ČR GD522/08/H003; GA MŠk 1M06030 Institutional research plan: CEZ:AV0Z50380511 Keywords : Agrobacterium * albinism * Hordeum Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.974, year: 2011

  4. Radiation risk factors and dose limits

    International Nuclear Information System (INIS)

    Barendsen, G.W.

    1979-01-01

    The contents of the ICRP publications 9 (1965) and 26 (1977) are outlined and the research conducted during these years considered. Expressions are derived for the frequency for induction of cancer from the most common irradiations - X rays, gamma rays and electrons. The dose limits advised by the ICRP are discussed and the first two fundamental principles are presented - that no one should be subjected to radiation without useful cause and that in those cases where irradiation is thought necessary, the medical, scientific, social and economic advantages need to be carefully considered with respect to the possible disadvantages. (C.F.)

  5. Pressure as a Limiting Factor for Life

    Directory of Open Access Journals (Sweden)

    Rachael Hazael

    2016-08-01

    Full Text Available Facts concerning the stability and functioning of key biomolecular components suggest that cellular life should no longer be viable above a few thousand atmospheres (200–300 MPa. However, organisms are seen to survive in the laboratory to much higher pressures, extending into the GPa or even tens of GPa ranges. This is causing main questions to be posed concerning the survival mechanisms of simple to complex organisms. Understanding the ultimate pressure survival of organisms is critical for food sterilization and agricultural products conservation technologies. On Earth the deep biosphere is limited in its extent by geothermal gradients but if life forms exist in cooler habitats elsewhere then survival to greater depths must be considered. The extent of pressure resistance and survival appears to vary greatly with the timescale of the exposure. For example, shock experiments on nanosecond timescales reveal greatly enhanced survival rates extending to higher pressure. Some organisms could survive bolide impacts thus allowing successful transport between planetary bodies. We summarize some of the main questions raised by recent results and their implications for the survival of life under extreme compression conditions and its possible extent in the laboratory and throughout the universe.

  6. Metabolic factors limiting performance in marathon runners.

    Science.gov (United States)

    Rapoport, Benjamin I

    2010-10-21

    Each year in the past three decades has seen hundreds of thousands of runners register to run a major marathon. Of those who attempt to race over the marathon distance of 26 miles and 385 yards (42.195 kilometers), more than two-fifths experience severe and performance-limiting depletion of physiologic carbohydrate reserves (a phenomenon known as 'hitting the wall'), and thousands drop out before reaching the finish lines (approximately 1-2% of those who start). Analyses of endurance physiology have often either used coarse approximations to suggest that human glycogen reserves are insufficient to fuel a marathon (making 'hitting the wall' seem inevitable), or implied that maximal glycogen loading is required in order to complete a marathon without 'hitting the wall.' The present computational study demonstrates that the energetic constraints on endurance runners are more subtle, and depend on several physiologic variables including the muscle mass distribution, liver and muscle glycogen densities, and running speed (exercise intensity as a fraction of aerobic capacity) of individual runners, in personalized but nevertheless quantifiable and predictable ways. The analytic approach presented here is used to estimate the distance at which runners will exhaust their glycogen stores as a function of running intensity. In so doing it also provides a basis for guidelines ensuring the safety and optimizing the performance of endurance runners, both by setting personally appropriate paces and by prescribing midrace fueling requirements for avoiding 'the wall.' The present analysis also sheds physiologically principled light on important standards in marathon running that until now have remained empirically defined: The qualifying times for the Boston Marathon.

  7. Metabolic factors limiting performance in marathon runners.

    Directory of Open Access Journals (Sweden)

    Benjamin I Rapoport

    2010-10-01

    Full Text Available Each year in the past three decades has seen hundreds of thousands of runners register to run a major marathon. Of those who attempt to race over the marathon distance of 26 miles and 385 yards (42.195 kilometers, more than two-fifths experience severe and performance-limiting depletion of physiologic carbohydrate reserves (a phenomenon known as 'hitting the wall', and thousands drop out before reaching the finish lines (approximately 1-2% of those who start. Analyses of endurance physiology have often either used coarse approximations to suggest that human glycogen reserves are insufficient to fuel a marathon (making 'hitting the wall' seem inevitable, or implied that maximal glycogen loading is required in order to complete a marathon without 'hitting the wall.' The present computational study demonstrates that the energetic constraints on endurance runners are more subtle, and depend on several physiologic variables including the muscle mass distribution, liver and muscle glycogen densities, and running speed (exercise intensity as a fraction of aerobic capacity of individual runners, in personalized but nevertheless quantifiable and predictable ways. The analytic approach presented here is used to estimate the distance at which runners will exhaust their glycogen stores as a function of running intensity. In so doing it also provides a basis for guidelines ensuring the safety and optimizing the performance of endurance runners, both by setting personally appropriate paces and by prescribing midrace fueling requirements for avoiding 'the wall.' The present analysis also sheds physiologically principled light on important standards in marathon running that until now have remained empirically defined: The qualifying times for the Boston Marathon.

  8. Spatial Assessment of Forest Ecosystem Functions and Services using Human Relating Factors for SDG

    Science.gov (United States)

    Song, C.; Lee, W. K.; Jeon, S. W.; Kim, T.; Lim, C. H.

    2015-12-01

    Application of ecosystem service concept in environmental related decision making could be numerical and objective standard for policy maker between preserving and developing perspective of environment. However, pursuing maximum benefit from natural capital through ecosystem services caused failure by losing ecosystem functions through its trade-offs. Therefore, difference between ecosystem functions and services were demonstrated and would apply human relating perspectives. Assessment results of ecosystem functions and services can be divided 3 parts. Tree growth per year set as the ecosystem function factor and indicated through so called pure function map. After that, relating functions can be driven such as water conservation, air pollutant purification, climate change regulation, and timber production. Overall process and amount are numerically quantified. These functional results can be transferred to ecosystem services by multiplying economic unit value, so function reflecting service maps can be generated. On the other hand, above services, to implement more reliable human demand, human reflecting service maps are also be developed. As the validation, quantified ecosystem functions are compared with former results through pixel based analysis. Three maps are compared, and through comparing difference between ecosystem function and services and inversed trends in function based and human based service are analysed. In this study, we could find differences in PF, FRS, and HRS in relation to based ecosystem conditions. This study suggests that the differences in PF, FRS, and HRS should be understood in the decision making process for sustainable management of ecosystem services. Although the analysis is based on in sort existing process separation, it is important to consider the possibility of different usage of ecosystem function assessment results and ecosystem service assessment results in SDG policy making. Furthermore, process based functional approach

  9. Additional factors of nuclear war potential effect on ecosystems

    International Nuclear Information System (INIS)

    Khatchinson, T.; Kharuehll, M.; Kropper, U.; Grover, G.

    1988-01-01

    Available information on response of organisms and ecosystems to increase of ultraviolet radiation, air borne pollutant concentrations, radiation and fires in case of nuclear war is generalized. The presented data are based on accumulated experience and experimental investigations. Potentiality of arising a great amount of stress effect localized regions is noted. Severe consequences for agriculture and population, particularly in sinergic stress effect, are not excluded. 169 refs.; 5 figs.; 25 tabs

  10. Biological factors of natural and artificial ecosystems stable (unstable) functioning

    Science.gov (United States)

    Pechurkin, Nikolai S.

    The problem of sustainable development of humanity on Earth and the problem of supporting human life in space have the same scientific and methodological bases. The key to solve both problems is a long term maintenance of balanced material cycle. As a whole, natural or artificial ecosystems are to be more closed than open, but their elements (links of systems) are to be substantially open in interactions with each other. Prolonged stable interactions of different links have to have unique joint results - closed material cycling or biotic turnover. It is necessary to include, at least, three types of main links into any system to support real material cycling: producers, consumers, reducers. Producer links are now under studies in many laboratories. It is evident that the higher productivity of link, the lower link stability. Especially, it concerns with parasite impact to plants. As usual, artificial ecosystems are more simple (incomplete) than natural ecosystems, sometimes, they have not enough links for prolonged stable functioning. For example, life support system for space flight can be incomplete in consumer link, having only some crew persons, instead of interacting populations of consumers. As for reducer link, it is necessary to "organize" a special coordinated work of microbial biocenoses to fulfill proper cycling. Possible evolution of links, their self development is a matter of special attention for the maintenance of prolonged stable functioning. It's the most danger for systems with populations of quickly reproducing, so-called, R - strategists, according to symbols of logistic equation. From another side, quick reproduction of R - strategists is able to increase artificial ecosystems and their links functioning. After some damages of system, R - strategist's link can be quickly "self repaired" up to level of normal functioning. Some experimental data of this kind and mathematical models are to be discussed in the paper. This work is supported by

  11. Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates.

    Science.gov (United States)

    Caldeira, Maria C; Lecomte, Xavier; David, Teresa S; Pinto, Joaquim G; Bugalho, Miguel N; Werner, Christiane

    2015-10-13

    Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs.

  12. Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates

    Science.gov (United States)

    Caldeira, Maria C.; Lecomte, Xavier; David, Teresa S.; Pinto, Joaquim G.; Bugalho, Miguel N.; Werner, Christiane

    2015-10-01

    Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs.

  13. Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors

    International Nuclear Information System (INIS)

    Marek, Michal V.; Janous, Dalibor; Taufarova, Klara; Havrankova, Katerina; Pavelka, Marian; Kaplan, Veroslav; Markova, Irena

    2011-01-01

    By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands. - Highlights: → Highest carbon sequestration potential in evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). → The final carbon gain of the grassland was negative (massive ecosystem respiration). → Climate is important factor of net primary productivity. → Carbon uptake is strongly affected by the ontogeny and a production strategy of ecosystem. - Identification of the apparent differences in the carbon storage by different ecosystem types.

  14. Variable Eddington factors and flux-limiting diffusion coefficients

    International Nuclear Information System (INIS)

    Whalen, P.P.

    1982-01-01

    Variable Eddington factors and flux limiting diffusion coefficients arise in two common techniques of closing the moment equations of transport. The first two moment equations of the full transport equation are still frequently used to solve many problems of radiative or particle transport. An approximate analysis, developed by Levermore, exhibits the relation between the coefficients of the two different techniques. This analysis is described and then used to test the validity of several commonly used flux limiters and Eddington factors. All of the ad-hoc flux limiters have limited validity. All of the variable Eddington factors derived from some underlying description of the angular distribution function are generally valid. The use of coefficients from Minerbo's elegant maximum entropy Eddington factor analysis is suggested for use in either flux limited diffusion or variable Eddington factor equations

  15. Factors limiting the operation of structures under high gradient

    International Nuclear Information System (INIS)

    Schriber, S.O.

    1986-01-01

    Factors limiting the operation of rf structures under high-gradient conditions are described. Included are recent rf measurements at laboratories in Europe, Asia, and North America and how these measurements relate to earlier data as exemplified by the use of the Kilpatrick criterion (Kp). Operation limitations will cover mechanical, geometry, thermal, and surface constraints and the associated impact on structure design, fabrication, and material selection. Generally, structures operating continuous wave (100% duty factor) appear to be limited to peak surface fields at about twice the Kilpatrick limit, whereas pulsed structures operating with pulse lengths less than a millisecond can attain peak surface fields five times the Kilpatrick limit

  16. Principal factors of soil spatial heterogeneity and ecosystem services at the Central Chernozemic Region of Russia

    Science.gov (United States)

    Vasenev, Ivan; Valentini, Riccardo

    2013-04-01

    The essential spatial heterogeneity is mutual feature for most natural and man-changed soils at the Central Chernozemic Region of Russia which is not only one of the biggest «food baskets» in RF but very important regulator of ecosystem principal services at the European territory of Russia. The original spatial heterogeneity of dominated here forest-steppe and steppe Chernozems and the other soils has been further complicated by a specific land-use history and different-direction soil successions due to environmental changes and more than 1000-year history of human impacts. The carried out long-term researches of representative natural, rural and urban landscapes in Kursk, Orel, Tambov and Voronezh oblasts give us the regional multi-factorial matrix of elementary soil cover patterns (ESCP) with different land-use practices and history, soil-geomorphologic features, environmental and microclimate conditions. The validation and ranging of the limiting factors of ESCP regulation and development, ecosystem principal services, land functional qualities and agroecological state have been done for dominating and most dynamical components of ESCP regional-typological forms - with application of regional and local GIS, soil spatial patterns mapping, traditional regression kriging, correlation tree models. The outcomes of statistical modeling show the essential amplification of erosion, dehumification and CO2 emission, acidification and alkalization, disaggregation and overcompaction processes due to violation of agroecologically sound land-use systems and traditional balances of organic matter, nutrients, Ca and Na in agrolandscapes. Due to long-term intensive and out-of-balance land-use practices the famous Russian Chernozems begin to lose not only their unique natural features of (around 1 m of humus horizon, 4-6% of Corg and favorable agrophysical features), but traditional soil cover patterns, ecosystem services and agroecological functions. Key-site monitoring

  17. Derivation of guideline values for gold (III) ion toxicity limits to protect aquatic ecosystems.

    Science.gov (United States)

    Nam, Sun-Hwa; Lee, Woo-Mi; Shin, Yu-Jin; Yoon, Sung-Ji; Kim, Shin Woong; Kwak, Jin Il; An, Youn-Joo

    2014-01-01

    This study focused on estimating the toxicity values of various aquatic organisms exposed to gold (III) ion (Au(3+)), and to propose maximum guideline values for Au(3+) toxicity that protect the aquatic ecosystem. A comparative assessment of methods developed in Australia and New Zealand versus the European Community (EC) was conducted. The test species used in this study included two bacteria (Escherichia coli and Bacillus subtilis), one alga (Pseudokirchneriella subcapitata), one euglena (Euglena gracilis), three cladocerans (Daphnia magna, Moina macrocopa, and Simocephalus mixtus), and two fish (Danio rerio and Oryzias latipes). Au(3+) induced growth inhibition, mortality, immobilization, and/or developmental malformations in all test species, with responses being concentration-dependent. According to the moderate reliability method of Australia and New Zealand, 0.006 and 0.075 mg/L of guideline values for Au(3+) were obtained by dividing 0.33 and 4.46 mg/L of HC5 and HC50 species sensitivity distributions (SSD) with an FACR (Final Acute to Chronic Ratio) of 59.09. In contrast, the EC method uses an assessment factor (AF), with the 0.0006 mg/L guideline value for Au(3+) being divided with the 48-h EC50 value for 0.60 mg/L (the lowest toxicity value obtained from short term results) by an AF of 1000. The Au(3+) guideline value derived using an AF was more stringent than the SSD. We recommend that more toxicity data using various bioassays are required to develop more accurate ecological risk assessments. More chronic/long-term exposure studies on sensitive endpoints using additional fish species and invertebrates not included in the current dataset will be needed to use other derivation methods (e.g., US EPA and Canadian Type A) or the "High Reliability Method" from Australia/New Zealand. Such research would facilitate the establishment of guideline values for various pollutants that reflect the universal effects of various pollutants in aquatic ecosystems. To

  18. Biophysical and sociocultural factors underlying spatial trade-offs of ecosystem services in semiarid watersheds

    Directory of Open Access Journals (Sweden)

    Marina García-Llorente

    2015-09-01

    Full Text Available Biophysical and social systems are linked to form social-ecological systems whose sustainability depends on their capacity to absorb uncertainty and cope with disturbances. In this study, we explored the key biophysical and socio-cultural factors underlying ecosystem service supply in two semiarid watersheds of southern Spain. These included variables associated with the role that freshwater flows and biodiversity play in securing the system's capacity to sustain essential ecosystem services and their relationship with social demand for services, local water governance, and land-use intensification. Our results reveal the importance of considering the invisible dimensions of water and biodiversity, i.e. green freshwater flows and trait-based indicators, because of their relevance to the supply of ecosystem services. Furthermore, they uncover the importance of traditional irrigation canals, a local water governance system, in maintaining the ecosystems' capacity to supply services. The study also highlights the complex trade-offs that occur because of the spatial mismatch between ecosystem service supply (upstream and ecosystem service demand (downstream in watersheds. Finally, we found that land-use intensification generally resulted in losses of the biophysical factors that underpin the supply of some ecosystem services, increases in social demand for less diversified services, and the abandonment of local governance practices. Attempts to manage social-ecological systems toward sustainability at the local scale should identify the key biophysical and socio-cultural factors that are essential for maintaining ecosystem services and should recognize existing interrelationships between them. Land-use management should also take into account ecosystem service trade-offs and the consequences resulting from land-use intensification.

  19. Nitrogen-limited mangrove ecosystems conserve N through dissimilatory nitrate reduction to ammonium

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, S.O.; Bonin, P.C.; Michotey, V.D.; Garcia, N.; LokaBharathi, P.A.

    , the occurrence of DNRA in mangroves has important implications for maintaining N levels and sustaining ecosystem productivity T his study also highlights the significance of DNRA in buffering the climate by modulating the production of the greenhouse gas nitrous...

  20. Classical limit of diagonal form factors and HHL correlators

    Energy Technology Data Exchange (ETDEWEB)

    Bajnok, Zoltan [MTA Lendület Holographic QFT Group, Wigner Research Centre,H-1525 Budapest 114, P.O.B. 49 (Hungary); Janik, Romuald A. [Institute of Physics, Jagiellonian University,ul. Łojasiewicza 11, 30-348 Kraków (Poland)

    2017-01-16

    We propose an expression for the classical limit of diagonal form factors in which we integrate the corresponding observable over the moduli space of classical solutions. In infinite volume the integral has to be regularized by proper subtractions and we present the one, which corresponds to the classical limit of the connected diagonal form factors. In finite volume the integral is finite and can be expressed in terms of the classical infinite volume diagonal form factors and subvolumes of the moduli space. We analyze carefully the periodicity properties of the finite volume moduli space and found a classical analogue of the Bethe-Yang equations. By applying the results to the heavy-heavy-light three point functions we can express their strong coupling limit in terms of the classical limit of the sine-Gordon diagonal form factors.

  1. Linking demand and supply factors in identifying cultural ecosystem services of urban green infrastructures

    DEFF Research Database (Denmark)

    Hegetschweiler, K. Tessa; de Vries, Sjerp; Arnberger, Arne

    2017-01-01

    characteristics of the ecosystem. We conducted a review of publications dealing with demand or social factors such as user needs, preferences and values as well as spatially explicit supply or physical factors such as amount of green space, (bio)diversity, recreational infrastructure, etc. and linking demand...... applicability for urban management and planning...

  2. Critical Success Factors for Limited Service Hotels in Malaysia

    OpenAIRE

    Wong, Chee Keng

    2015-01-01

    Critical success factors were used originally in Information technology areas when it was first introduced but has since been applied generically in other industries. This study explores the critical success factors for limited service hotels in Malaysia from both customer and hotel operator/ business owners’ perspective. The literature presents information from tourism in general and in Malaysia, definition of limited service hotels and its relevance to the hospitality industry in Malaysia, ...

  3. Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors.

    Science.gov (United States)

    Marek, Michal V; Janouš, Dalibor; Taufarová, Klára; Havránková, Kateřina; Pavelka, Marian; Kaplan, Věroslav; Marková, Irena

    2011-05-01

    By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Nutrient limitation on ecosystem productivity and processes of mature and old-growth subtropical forests in China.

    Directory of Open Access Journals (Sweden)

    Enqing Hou

    Full Text Available Nitrogen (N is considered the dominant limiting nutrient in temperate regions, while phosphorus (P limitation frequently occurs in tropical regions, but in subtropical regions nutrient limitation is poorly understood. In this study, we investigated N and P contents and N:P ratios of foliage, forest floors, fine roots and mineral soils, and their relationships with community biomass, litterfall C, N and P productions, forest floor turnover rate, and microbial processes in eight mature and old-growth subtropical forests (stand age >80 yr at Dinghushan Biosphere Reserve, China. Average N:P ratios (mass based in foliage, litter (L layer and mixture of fermentation and humus (F/H layer, and fine roots were 28.3, 42.3, 32.0 and 32.7, respectively. These values are higher than the critical N:P ratios for P limitation proposed (16-20 for foliage, ca. 25 for forest floors. The markedly high N:P ratios were mainly attributed to the high N concentrations of these plant materials. Community biomass, litterfall C, N and P productions, forest floor turnover rate and microbial properties were more strongly related to measures of P than N and frequently negatively related to the N:P ratios, suggesting a significant role of P availability in determining ecosystem production and productivity and nutrient cycling at all the study sites except for one prescribed disturbed site where N availability may also be important. We propose that N enrichment is probably a significant driver of the potential P limitation in the study area. Low P parent material may also contribute to the potential P limitation. In general, our results provided strong evidence supporting a significant role for P availability, rather than N availability, in determining ecosystem primary productivity and ecosystem processes in subtropical forests of China.

  5. Detecting changes in water limitation in the West using integrated ecosystem modeling approaches

    Science.gov (United States)

    Poulter, B.; Hoy, J.; Emmett, K.; Cross, M.; Maneta, M. P.; Al-Chokhachy, R.

    2016-12-01

    Water in the western United States is the critical currency for determining a range of ecosystem services, such as wildlife habitat, carbon sequestration, and timber and water resources for an expanding human population. The current generation of catchment models trades a detailed representation of hydrologic processes for a generalization of vegetation processes and thus ignores many land-surface feedbacks that are driven by physiological responses to atmospheric CO2 and changes in vegetation structure following disturbance and climate change. Here we demonstrate how catchment scale modeling can better couple vegetation dynamics and disturbance processes to reconstruct historic streamflow, stream temperature and vegetation greening for the Greater Yellowstone Ecosystem. Using a new catchment routing model coupled to the LPJ-GUESS dynamic global vegetation model, simulations are made at 1 km spatial resolution using two different climate products. Decreased winter snowpack has led to increasing spring runoff and declines in summertime slow, and increasing the likelihood that stream temperature exceeds thresholds for cold-water fish growth. Since the mid-1980s, vegetation greening is projected by both the model and detected from space-borne normalized difference vegetation index observations. These greening trends are superimposed on a landscape matrix defined by frequent disturbance and intensive land management, making the climate and CO2 fingerprint difficult to discern. Integrating dynamical vegetation models with in-situ and spaceborne measurements to understand and interpret catchment-scale trends in water availability has potential to better disentangle historical climate, CO2, and human drivers and their ecosystem consequences.

  6. Plant responses, climate pivot points, and trade-offs in water-limited ecosystems

    Science.gov (United States)

    Munson, S. M.; Bunting, E.

    2017-12-01

    Ecosystem transitions and thresholds are conceptually well-defined and have become a framework to address vegetation response to climate change and land-use intensification, yet there are few approaches to define the environmental conditions which can lead to them. We demonstrate a novel climate pivot point approach using long-term monitoring data from a broad network of permanent plots, satellite imagery, and experimental treatments across the southwestern U.S. The climate pivot point identifies conditions that lead to decreased plant performance and serves as an early warning sign of increased vulnerability of crossing a threshold into an altered ecosystem state. Plant responses and climate pivot points aligned with the lifespan and structural characteristics of species, were modified by soil and landscape attributes of a site, and had non-linear dynamics in some cases. Species with strong increases in abundance when water was available were most susceptible to losses during water shortages, reinforcing plant energetic and physiological tradeoffs. Future research to uncover the heterogeneity of plant responses and climate pivot points at multiple scales can lead to greater understanding of shifts in ecosystem productivity and vulnerability to climate change.

  7. Nitrogen, organic carbon and sulphur cycling in terrestrial ecosystems: linking nitrogen saturation to carbon limitation of soil microbial processes

    Czech Academy of Sciences Publication Activity Database

    Kopáček, Jiří; Cosby, B. J.; Evans, C. D.; Hruška, J.; Moldan, F.; Oulehle, F.; Šantrůčková, H.; Tahovská, K.; Wright, R. F.

    2013-01-01

    Roč. 115, 1-3 (2013), s. 33-51 ISSN 0168-2563. [BIOGEOMON : international symposium on ecosystem behavior /7./. Northport, 15.07.2012-20.07.2012] R&D Projects: GA ČR(CZ) GAP504/12/1218 Institutional support: RVO:60077344 Keywords : nitrogen * carbon * sulphur * acidification * forest soil * modelling Subject RIV: DJ - Water Pollution ; Quality Impact factor: 3.730, year: 2013

  8. Mycobacterium ulcerans dynamics in aquatic ecosystems are driven by a complex interplay of abiotic and biotic factors.

    Science.gov (United States)

    Garchitorena, Andrés; Guégan, Jean-François; Léger, Lucas; Eyangoh, Sara; Marsollier, Laurent; Roche, Benjamin

    2015-07-28

    Host-parasite interactions are often embedded within complex host communities and can be influenced by a variety of environmental factors, such as seasonal variations in climate or abiotic conditions in water and soil, which confounds our understanding of the main drivers of many multi-host pathogens. Here, we take advantage of a combination of large environmental data sets on Mycobacterium ulcerans (MU), an environmentally persistent microorganism associated to freshwater ecosystems and present in a large variety of aquatic hosts, to characterize abiotic and biotic factors driving the dynamics of this pathogen in two regions of Cameroon. We find that MU dynamics are largely driven by seasonal climatic factors and certain physico-chemical conditions in stagnant and slow-flowing ecosystems, with an important role of pH as limiting factor. Furthermore, water conditions can modify the effect of abundance and diversity of aquatic organisms on MU dynamics, which suggests a different contribution of two MU transmission routes for aquatic hosts (trophic vs environmental transmission) depending on local abiotic factors.

  9. The investigation of limiting factors of earnings management for ...

    African Journals Online (AJOL)

    The current study was to examine the limiting factors of earnings management for companies' listed Tehran stock exchange. The study was a kind of applied, descriptive- correlative research. All listed companies in Tehran stock exchange were selected as statistical population during 2009 to 2013. So, data was gathered by ...

  10. The limiting factor relationship between geoelectric and hydraulic ...

    African Journals Online (AJOL)

    The objectives of study included the estimation of the aquifer hydraulic parameters of the Pleistocene aged alluvium Formation from both the geoelectric and pumping test datasets with a view to determining empirical and limiting factor relationships and groundwater conditions. 106 geoelectric sounding and seventeen ...

  11. Factors limiting and preventing emerging farmers to progress to ...

    African Journals Online (AJOL)

    The findings demonstrated that the specific limiting factors emerging farmers face are poor physical infrastructure such as poor roads, lack of transportation to the markets from the farms, lack of marketing skills and information, poor market infrastructure, and high transaction costs, insufficient land availability to expand ...

  12. Perceived Factors Limiting Rice Production in Patigi Local ...

    African Journals Online (AJOL)

    The study examined the perceived factors limiting rice production in five selected villages in Patigi Local Government Area of Kwara State, Nigeria. The study area was purposively selected based on their known potentials for rice production. One Hundred and Ten (110) rice farmers were selected for the study.

  13. Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors

    Czech Academy of Sciences Publication Activity Database

    Marek, Michal V.; Janouš, Dalibor; Taufarová, Klára; Havránková, Kateřina; Pavelka, Marian; Kaplan, Věroslav; Marková, I.

    2011-01-01

    Roč. 159, č. 5 (2011), s. 1035-1039 ISSN 0269-7491 R&D Projects: GA MŽP(CZ) SP/1A6/108/07; GA MŠk 2B06068 Institutional research plan: CEZ:AV0Z60870520 Keywords : carbon fluxes * net ecosystem exchange * spruce forest * beech forest * Grassland * agroecosystem * wetland * climate factors Subject RIV: EH - Ecology, Behaviour Impact factor: 3.746, year: 2011

  14. [A review on carbon and water interactions of forest ecosystem and its impact factors].

    Science.gov (United States)

    Song, Chun-lin; Sun, Xiang-yang; Wang, Gen-xu

    2015-09-01

    Interaction between carbon and water in forest ecosystem is a coupling process in terrestrial ecosystem, which is an indispensable aspect for the study of forest carbon pool, ecohydrological processes and the responses to global change. In the context of global change, the interaction and coupling of carbon and water in forest ecosystem has attracted much attention among scientists. In this paper, we reviewed the process mechanism of forest carbon and water relationships based on previous studies, which consisted of advance in forest water use efficiency, carbon and water interactions at different scales, scaling, and model simulation. We summed up the factors affecting for- est water and carbon interaction, including water condition, carbon dioxide enrichment, warming, nitrogen deposition, ozone concentration variation, solar radiation, and altitudinal gradients. Finally, we discussed the problems in the previous studies, and prospected the possible future research fields, among which we thought the inherent dynamics mechanism and scaling of forest carbon and water interactions should be enhanced.

  15. Factors limiting heterotrophic bacterial production in the southern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    F. Van Wambeke

    2008-05-01

    Full Text Available The role of potential factors limiting bacterial growth was investigated along vertical and longitudinal gradients across the South Eastern Pacific Gyre. The effects of glucose, nitrate, ammonium and phosphate additions on heterotrophic bacterial production (using leucine technique were studied in parallel in unfiltered seawater samples incubated under natural daily irradiance. The enrichments realized on the subsurface showed three types of responses. From 141° W (Marquesas plateau to approx 125° W, bacteria were not bottom-up controlled, as confirmed by the huge potential of growth in non-enriched seawater (median of enhancement factor×39 in 24 h. Within the Gyre (125° W–95° W, nitrogen alone stimulated leucine incorporation rates (median×4.2, but rapidly labile carbon (glucose became a second limiting factor (median×37 when the two elements were added. Finally from the border of the gyre to the Chilean upwelling (95° W–73° W, labile carbon was the only factor stimulating heterotrophic bacterial production. Interaction between phytoplankton and heterotrophic bacterial communities and the direct versus indirect effect of iron and macronutrients on bacterial production were also investigated in four selected sites: two sites on the vicinity of the Marquesas plateau, the centre of the gyre and the Eastern border of the gyre. Both phytoplankton and heterotrophic bacteria were limited by availability of nitrogen within the gyre, but not by iron. Iron limited phytoplankton at Marquesas plateau and at the eastern border of the gyre. However 48 h enrichment experiments were not sufficient to show any clear limitation of heterotrophic bacteria within Marquesas plateau and showed a limitation of these organisms by labile carbon in the eastern border of the Gyre.

  16. Physiological strategies of co-occurring oaks in a water- and nutrient-limited ecosystem

    Science.gov (United States)

    Heidi Renninger; Nicholas Carlo; Kenneth L. Clark; Karina V.R. Schafer

    2014-01-01

    Oak species are well suited to water-limited conditions by either avoiding water stress through deep rooting or tolerating water stress through tight stomatal control. In co-occurring species where resources are limited, species may either partition resources in space and/or time or exhibit differing efficiencies in the use of limited resources. Therefore, this study...

  17. Ecosystem Service Value Assessment and Contribution Factor Analysis of Land Use Change in Miyun County, China

    Directory of Open Access Journals (Sweden)

    Ping Zhang

    2015-06-01

    Full Text Available Unreasonable land use planning can reduce ecosystem service value and result in unsustainable land use. In this paper, the changes of ecosystem service value were investigated by using the GIS and dynamic simulation model of land use in Miyun of Beijing, China, based on the land use at four time points including 1991, 2006, 2021 and one improved scenario, respectively. The results showed the total ecosystem service value of Miyun was about 2968.34 million Yuan in 1991, 3304.72 million Yuan in 2006, 3106.48 million Yuan in 2021, and 3759.77 million Yuan in the improved scenario. In terms of ecosystem service function, the functions of water supply and soil formation and retention accounted for the largest proportion, which were 19.99% and 14.58% respectively; whereas the functions of food supply and recreation and culture were only 1.83% and 5.99%, respectively. Coefficients of sensitivity for forest cover, water bodies and arable land were relatively large, which were 0.73, 0.28 and 0.14, respectively. The contribution factors of total ecosystem service value with the land use change during different periods were mainly the unused land to forest cover and arable land, which respectively accounted for more than 63% and 21% of the contribution rate. These results suggested that sustainable land use planning should be undertaken with emphasis on vegetation restoration and protection of water bodies.

  18. Climatological Implications of Deep-Rooting in Water-Limited Ecosystems

    Science.gov (United States)

    Amenu, G. G.; Kumar, P.

    2005-12-01

    In vegetated ecosystems, plants are the primary channels that connect the soil with the atmosphere (through water, energy, carbon, and nutrient cycles), with plant roots controlling the below-ground dynamics. Recently, several observational evidences are emerging which suggests the existence of plant roots much deeper in the soil/rock profile than the depth usually perceived in existing hydroclimatological and hydroecological models. In this study, using land surface model, we assess the effects of vegetation deep-rooting on (a) moisture and temperature redistribution in the soil profile, (b) energy flux partitioning at the land surface, and (c) net primary productivity of vegetated ecosystems. Three sites characterized by different vegetation, soil, and climate (all located in arid to sub-humid regions of the United States) were studied. The sites include the Mogollon Rim in Arizona, the Edwards Plateau in Texas, and the Southern Piedmont in Georgia. Soil depths of up to 10 m are investigated. Results of this modeling effort and its implications for climatological modeling will be presented.

  19. Modeling plant competition for soil water balance in Water-limited Mediterranean Ecosystems

    Science.gov (United States)

    Cortis, C.; Montaldo, N.

    2009-12-01

    In heterogeneous ecosystems, such Mediterranean ecosystems, contrasting plant functional types (PFTs, e.g., grass and woody vegetation) compete for the water use. In these complex ecosystems current modeling approaches need to be improved due to a general lack of knowledge about the relationship between ET and the plant survival strategies for the different PFTs under water stress. Indeed, still unsolved questions are: how the PFTs (in particular the root systems) compete for the water use, the impact of this competition on the water balance terms, and the role of the soil type and soil depth in this competition. For this reasons an elaborated coupled Vegetation dynamic model (VDM) - land surface model (LSM) model able to also predict root distribution of competing plant systems is developed. The transport of vertical water flow in the unsaturated soil is modelled through a Richards’ equation based model. The water extraction (sink) term is considered as the root water uptake. Two VDMs predict vegetation dynamics, including spatial and temporal distribution/evolution of the root systems in the soil of two competing species (grass and woody vegetation). An innovative method for solving the unlinear system of predicting equations is proposed. The coupled model is able to predict soil and root water potential of the two competing plant species. The model is tested for the Orroli case study, situated in the mid-west of Sardinia within the Flumendosa river watershed. The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and coark oaks, different shrubs and herbaceous species. In particular two contrasting plant functional types (grass and woody vegetation) have been included. The model well predict the soil moisture and vegetation dynamics for the case study, and significantly different root potentials are predicted for the two PFTs, highlighting the root competition for the water use. The soil depth is low in the case

  20. Modeling plant competition for water use in Water-limited Mediterranean Ecosystems

    Science.gov (United States)

    Cortis, C.; Montaldo, N.

    2009-04-01

    In heterogeneous ecosystems, such Mediterranean ecosystems, contrasting plant functional types (PFTs, e.g., grass and woody vegetation) compete for the water use. In these complex ecosystems current modeling approaches need to be improved due to a general lack of knowledge about the relationship between ET and the plant survival strategies for the different PFTs under water stress. Indeed, still unsolved questions are: how the PFTs (in particular the root systems) compete for the water use, the impact of this competition on the water balance terms, and the role of the soil type and soil depth in this competition. For this reasons an elaborated coupled Vegetation dynamic model (VDM) - land surface model (LSM) model able to also predict root distribution of competing plant systems is developed. The transport of vertical water flow in the unsaturated soil is modelled through a Richards' equation based model. The water extraction (sink) term is considered as the root water uptake. Two VDMs predict vegetation dynamics, including spatial and temporal distribution/evolution of the root systems in the soil of two competing species (grass and woody vegetation). An innovative method for solving the unlinear system of predicting equations is proposed. The coupled model is able to predict soil and root water potential of the two competing plant species. The model is tested for the Orroli case study, situated in the mid-west of Sardinia within the Flumendosa river watershed. The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and coark oaks, different shrubs and herbaceous species. In particular two contrasting plant functional types (grass and woody vegetation) have been included. The model well predict the soil moisture and vegetation dynamics for the case study, and significantly different root potentials are predicted for the two PFTs, highlighting the root competition for the water use. The soil depth is low in the case

  1. Limiting factors for growth and development of domestic mites

    NARCIS (Netherlands)

    Lynden, A.M.T. van; Kort, H.S.M.; Koren, L.G.H.; Pernot, C.E.E.; Bronswijk, J.E.M.H. van

    1996-01-01

    A quarter to half of European households are at risk of health damage due to mites in their home. House dust mites (family Pyroglyphidae) and storage mites (families Acaridae and Gly-cyphagidae) are present; both groups being specific for different ecosystems: house-dust ecosystem of textiles

  2. Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphere

    Science.gov (United States)

    Ram Oren; David S. Ellsworth; Kurt H. Johnsen; Nathan Phillips; Brent E. Ewers; Chris Maier; Karina V.R. Schafer; Heather McCarthy; George Hendrey; Steven G. McNulty; Gabriel G. Katul

    2001-01-01

    Northern mid-latitude forests are a large terrestrial carbon sink. Ignoring nutrient limitations, large increases in carbon sequestration from carbon dioxide (CO2) fertilization are expected in these forests. Yet, forests are usually relegated to sites of moderate to poor fertility, where tree growth is often limited by nutrient supply, in...

  3. Nutrient limitation of soil microbial activity during the earliest stages of ecosystem development.

    Science.gov (United States)

    Castle, Sarah C; Sullivan, Benjamin W; Knelman, Joseph; Hood, Eran; Nemergut, Diana R; Schmidt, Steven K; Cleveland, Cory C

    2017-11-01

    A dominant paradigm in ecology is that plants are limited by nitrogen (N) during primary succession. Whether generalizable patterns of nutrient limitation are also applicable to metabolically and phylogenetically diverse soil microbial communities, however, is not well understood. We investigated if measures of N and phosphorus (P) pools inform our understanding of the nutrient(s) most limiting to soil microbial community activities during primary succession. We evaluated soil biogeochemical properties and microbial processes using two complementary methodological approaches-a nutrient addition microcosm experiment and extracellular enzyme assays-to assess microbial nutrient limitation across three actively retreating glacial chronosequences. Microbial respiratory responses in the microcosm experiment provided evidence for N, P and N/P co-limitation at Easton Glacier, Washington, USA, Puca Glacier, Peru, and Mendenhall Glacier, Alaska, USA, respectively, and patterns of nutrient limitation generally reflected site-level differences in soil nutrient availability. The activities of three key extracellular enzymes known to vary with soil N and P availability developed in broadly similar ways among sites, increasing with succession and consistently correlating with changes in soil total N pools. Together, our findings demonstrate that during the earliest stages of soil development, microbial nutrient limitation and activity generally reflect soil nutrient supply, a result that is broadly consistent with biogeochemical theory.

  4. [Factors influencing the variability in soil heterotrophic respiration from terrestrial ecosystem in China].

    Science.gov (United States)

    Xie, Wei; Chen, Shu-Tao; Hu, Zheng-Hua

    2014-01-01

    Soil heterotrophic respiration is one of the key factors for estimating ecosystem carbon balance. Measurement data of soil heterotrophic respiration from terrestrial ecosystem in China were collected. Climate data (annual precipitation and annual mean air temperature) and relevant environmental factors (e. g. tree age) were also collected. Results indicated that the relationship between heterotrophic respiration and soil respiration could be explained by a power function. Heterotrophic respiration increased with the increase of soil respiration. The power function explained 73% of the variability (R2 = 0.730, P power function could be used to explain the relationship between the ratio of heterotrophic respiration to soil respiration and tree age. Further investigation showed that the relationship between measured annual heterotrophic respiration and modeled heterotrophic respiration by using an empirical model could be described by a linear function, indicating that the empirical model well fitted the variability in heterotrophic respiration.

  5. Alpine ecosystems

    Science.gov (United States)

    P.W. Rundel; C.I. Millar

    2016-01-01

    Alpine ecosystems are typically defined as those areas occurring above treeline, while recognizing that alpine ecosystems at a local scale may be found below this boundary for reasons including geology, geomorphology, and microclimate. The lower limit of the alpine ecosystems, the climatic treeline, varies with latitude across California, ranging from about 3500 m in...

  6. Characterization factors for global warming in life cycle assessment based on damages to humans and ecosystems.

    Science.gov (United States)

    De Schryver, An M; Brakkee, Karin W; Goedkoop, Mark J; Huijbregts, Mark A J

    2009-03-15

    Human and ecosystem health damage due to greenhouse gas (GHG) emissions is generally poorly quantified in the life cycle assessment of products, preventing an integrated comparison of the importance of GHGs with other stressor types, such as ozone depletion and acidifying emissions. In this study, we derived new characterization factors for 63 GHGs that quantify the impact of an emission change on human and ecosystem health damage. For human health damage, the Disability Adjusted Life Years (DALYs) per unit emission related to malaria, diarrhea, malnutrition, drowning, and cardiovascular diseases were quantified. For ecosystem health damage, the Potentially Disappeared Fraction (PDF) over space and time of various species groups, including plants, butterflies, birds, and mammals, per unit emission was calculated. The influence of value choices in the modeling procedure was analyzed by defining three coherent scenarios, based on Cultural theory perspectives. It was found that the characterization factor for human health damage by carbon dioxide (CO2) ranges from 1.1 x 10(-2) to 1.8 x 10(+1) DALY per kton of emission, while the characterization factor for ecosystem damage by CO2 ranges from 5.4 x 10(-2) to 1.2 x 10(+1) disappeared fraction of species over space and time ((km2 x year)/kton), depending on the scenario chosen. The characterization factor of a GHG can change up to 4 orders of magnitude, depending on the scenario. The scenario-specific differences are mainly explained by the choice for a specific time horizon and stresses the importance of dealing with value choices in the life cycle impact assessment of GHG emissions.

  7. Model-based assessment of estuary ecosystem health using the latent health factor index, with application to the richibucto estuary.

    Directory of Open Access Journals (Sweden)

    Grace S Chiu

    Full Text Available The ability to quantitatively assess ecological health is of great interest to those tasked with monitoring and conserving ecosystems. For decades, biomonitoring research and policies have relied on multimetric health indices of various forms. Although indices are numbers, many are constructed based on qualitative procedures, thus limiting the quantitative rigor of the practical interpretations of such indices. The statistical modeling approach to construct the latent health factor index (LHFI was recently developed. With ecological data that otherwise are used to construct conventional multimetric indices, the LHFI framework expresses such data in a rigorous quantitative model, integrating qualitative features of ecosystem health and preconceived ecological relationships among such features. This hierarchical modeling approach allows unified statistical inference of health for observed sites (along with prediction of health for partially observed sites, if desired and of the relevance of ecological drivers, all accompanied by formal uncertainty statements from a single, integrated analysis. Thus far, the LHFI approach has been demonstrated and validated in a freshwater context. We adapt this approach to modeling estuarine health, and illustrate it on the previously unassessed system in Richibucto in New Brunswick, Canada, where active oyster farming is a potential stressor through its effects on sediment properties. Field data correspond to health metrics that constitute the popular AZTI marine biotic index and the infaunal trophic index, as well as abiotic predictors preconceived to influence biota. Our paper is the first to construct a scientifically sensible model that rigorously identifies the collective explanatory capacity of salinity, distance downstream, channel depth, and silt-clay content-all regarded a priori as qualitatively important abiotic drivers-towards site health in the Richibucto ecosystem. This suggests the potential

  8. Model-based assessment of estuary ecosystem health using the latent health factor index, with application to the richibucto estuary.

    Science.gov (United States)

    Chiu, Grace S; Wu, Margaret A; Lu, Lin

    2013-01-01

    The ability to quantitatively assess ecological health is of great interest to those tasked with monitoring and conserving ecosystems. For decades, biomonitoring research and policies have relied on multimetric health indices of various forms. Although indices are numbers, many are constructed based on qualitative procedures, thus limiting the quantitative rigor of the practical interpretations of such indices. The statistical modeling approach to construct the latent health factor index (LHFI) was recently developed. With ecological data that otherwise are used to construct conventional multimetric indices, the LHFI framework expresses such data in a rigorous quantitative model, integrating qualitative features of ecosystem health and preconceived ecological relationships among such features. This hierarchical modeling approach allows unified statistical inference of health for observed sites (along with prediction of health for partially observed sites, if desired) and of the relevance of ecological drivers, all accompanied by formal uncertainty statements from a single, integrated analysis. Thus far, the LHFI approach has been demonstrated and validated in a freshwater context. We adapt this approach to modeling estuarine health, and illustrate it on the previously unassessed system in Richibucto in New Brunswick, Canada, where active oyster farming is a potential stressor through its effects on sediment properties. Field data correspond to health metrics that constitute the popular AZTI marine biotic index and the infaunal trophic index, as well as abiotic predictors preconceived to influence biota. Our paper is the first to construct a scientifically sensible model that rigorously identifies the collective explanatory capacity of salinity, distance downstream, channel depth, and silt-clay content-all regarded a priori as qualitatively important abiotic drivers-towards site health in the Richibucto ecosystem. This suggests the potential effectiveness of the

  9. Fuel biomass and combustion factors associated with fires in savanna ecosystems of South Africa and Zambia

    Science.gov (United States)

    Shea, Ronald W.; Shea, Barbara W.; Kauffman, J. Boone; Ward, Darold E.; Haskins, Craig I.; Scholes, Mary C.

    1996-10-01

    Fires are dominant factors in shaping the structure and composition of vegetation in African savanna ecosystems. Emissions such as CO2, NOx, CH4, and other compounds originating from these fires are suspected to contribute substantially to changes in global biogeochemical processes. Limited quantitative data exist detailing characteristics of biomass, burning conditions, and the postfire environment in African savannas. Fourteen test sites, differentiated by distinct burn frequency histories and land-use patterns, were established and burned during August and September 1992 in savanna parklands of South Africa and savanna woodlands of Zambia. Vegetation physiognomy, available fuel loads, the levels of biomass consumed by fire, environmental conditions, and fire behavior are described. In the South African sites, total aboveground fuel loads ranged from 2218 to 5492 kg ha-1 where fire return intervals were 1-4 years and exceeded 7000 kg ha-1 at a site subjected to 38 years of fire exclusion. However, fireline intensity was only 1419 kW m-1 at the fire exclusion site, while ranging from 480 to 6130 kW m-1 among the frequent fire sites. In Zambia, total aboveground fuel loads ranged from 3164 kg ha-1 in a hydromorphic grassland to 7343 kg ha-1 in a fallow shifting cultivation site. Dormant grass and litter constituted 70-98% of the total fuel load among all sites. Although downed woody debris was a relatively minor fuel component at most sites, it constituted 43-57% of the total fuel load in the fire exclusion and shifting cultivation sites. Fire line intensity ranged between 1734 and 4061 kW m-1 among all Zambian sites. Mean grass consumption generally exceeded 95%, while downed woody debris consumption ranged from 3 to 73% at all sites. In tropical savannas and savanna woodlands of southern Africa, differences in environmental conditions, land- use patterns, and fire regimes influence vegetation characteristics and thus influence fire behavior and biomass

  10. Extreme drought event and shrub invasion combine to reduce ecosystem functioning and resilience in water-limited climates

    Science.gov (United States)

    Caldeira, Maria; Lecomte, Xavier; David, Teresa; Pinto, Joaquim; Bugalho, Miguel; Werner, Christiane

    2016-04-01

    ). Caldeira M.C., Lecomte X., David T.S., Pinto J.G., Bugalho M.N. & Werner C. (2015). Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates. Scientific Reports, 5, 15110.

  11. Tropical Andean ecosystems and the need to keep warming limits below a +1.5°C threshold

    Science.gov (United States)

    Ruiz-Carrascal, D.; Herzog, S. K.; Guitierrez Lagoueyte, M. E.; Gonzalez-Duque, D.; Cuevas-Moreno, J.; del Valle, J. I.; Andreu-Hayles, L.; Herrera, D. A.; Martínez, R.

    2017-12-01

    Long-term climate change and rapid land-use change are synergistically threatening the integrity and functioning of tropical Andean ecosystems. The main goal of our research was to integrate climate change projections, biodiversity data and anthropogenically driven ecosystem disruption assessments to quantify the vulnerability of Andean ecosystems and species to global change at a local scale. We merged discernible trends in local quality-controlled weather station data with reanalysis data, as well as with historical and prospective simulation outputs of five well-known GCMs to assess a long-term context for the analysis of climate change exposure (temperature severity intervals). Individual, medium-term, multi-member GCM simulations included: altitude-corrected 2046-2065 (IPCC-AR4) climate change scenarios for the A1B emission scenario; and spatially-downscaled 2040-2069 (IPCC-AR5) projections for the RCP4.5. Previous studies reported mean annual temperature anomaly intervals that resulted in exceedingly high thresholds: the lowest severity interval ( +2.71°C). The least severe interval extended up to the threshold widely recognized as `dangerous' climate change, thereby leading to an underestimation of the true vulnerability of Andean species. Our analyses suggest that temperature anomalies for the full extent of the tropical Andes will likely range from low ( +2.61°C), exceeding the threshold of 'natural' climate variability (+1.78°C). Our results suggest that most species that were used as proxies of ecosystem vulnerabilities will likely experience overall low-to-medium-to-high temperature increases. Since many of them have potentially high sensitivity to such long-term changes, Andean species will likely experience greatly increases in vulnerability. The already-disrupted Andean ecosystems will suffer a further climatic stress, which will worsen the well-known detrimental synergies between climate and land-use changes. There is an imperative need to

  12. Soil moisture and wild olive tree transpiration relationship in a water-limited Mediterranean ecosystem.

    Science.gov (United States)

    Curreli, M.; Montaldo, N.; Oren, R.

    2016-12-01

    Typically, during the dry summers, Mediterranean ecosystems are characterized by a simple dual PFTs system with strong-resistant woody vegetation and bare soil, since grass died. In these conditions the combined use of sap flow measurements, based on Granier's thermo-dissipative probes, eddy covariance technique and soil water content measurements provides a robust estimation of evapotranspiration (ET). An eddy covariance micrometeorological tower, thermo-dissipative probes based on the Granier technique and TDR sensors have been installed in the Orroli site in Sardinia (Italy). The site landscape is a mixture of Mediterranean patchy vegetation types: wild olives, different shrubs and herbaceous species, which died during the summer. 33 sap flow sensors have been installed at the Orroli site into 15 wild olives clumps with different characteristics (tree size, exposition to wind, solar radiation and soil depth). Sap flow measurements show the significantly impacts on transpiration of soil moisture, radiation and vapor pressure deficit (VPD). In addition ET is strongly influenced by the tree position into the clump. Results show a significant difference in sap flow rate for the south exposed trees compared to inside clump and north exposed trees. Using an innovative scaling procedure, the transpiration calculated from sap flow measurements have been compared to the eddy covariance ET. Sap flow measurements show night time uptake allows the recharge of the stem capacity, depleted during the day before due to transpiration. The night uptake increases with increasing VPD and transpiration but surprisingly it is independent to soil water content. Soil moisture probes allow monitoring spatial and temporal dynamics of water content at different soil depth and distance to the trees, and estimating its correlation with hydraulic lift. During the light hours soil moisture is depleted by roots to provide the water for transpiration and during night time the lateral roots

  13. Biotic elements of NPP techno-ecosystem

    International Nuclear Information System (INIS)

    Protasov, A.A.; Silaeva, A.A.

    2013-01-01

    Specific features of biotic elements in the NPP techno-ecosystems were considered and compared with natural ecosystems. Relationships between biotic communities and environmental factors that are specific to the techno-ecosystems were discussed, and the problems of limitation of biological hindrances in operation of equipment, principles of hydrobiological and environmental monitoring were considered.

  14. Molybdenum limitation of microbial nitrogen assimilation in aquatic ecosystems and pure cultures

    Directory of Open Access Journals (Sweden)

    Jennifer B. Glass

    2012-09-01

    Full Text Available Molybdenum (Mo is an essential micronutrient for biological assimilation of nitrogen gas and nitrate because it is present in the cofactors of nitrogenase and nitrate reductase enzymes. Although Mo is the most abundant transition metal in seawater (107 nM, it is present in low concentrations in most freshwaters, typically <20 nM. In 1960, it was discovered that primary productivity was limited by Mo scarcity (2-4 nM in Castle Lake, a small, meso-oligotrophic lake in northern California. Follow up studies demonstrated that Mo also limited primary productivity in lakes in New Zealand, Alaska and the Sierra Nevada. Research in the 1970s and 1980s showed that Mo limited primary productivity and nitrate uptake in Castle Lake only during periods of the growing season when nitrate concentrations were relatively high because ammonium assimilation does not require Mo. In the years since, research has shifted to investigate whether Mo limitation also occurs in marine and soil environments. Here we review studies of Mo limitation of nitrogen assimilation in natural communities and pure microbial cultures. We also summarize new data showing that the simultaneous addition of Mo and nitrate causes increased activity of proteins involved in nitrogen assimilation in the hypolimnion of Castle Lake when ammonium is scarce. Furthermore, we suggest that meter-scale Mo and oxygen profiles from Castle Lake are consistent with the hypothesis that nitrogen-fixing cyanobacteria in freshwater periphyton communities have higher Mo requirements than other microbial communities. Finally, we present topics for future research related to Mo bioavailability through time and with changing oxidation state.

  15. Investigation of the factors influencing radiocesium concentrations of fish inhabiting natural aquatic ecosystems

    International Nuclear Information System (INIS)

    Jinks, S.M.

    1975-01-01

    Distributions of radioactive and stable cesium were determined in water, sediment, and biota from eight different aquatic ecosystems between 1971 and 1973. The ecosystems included four lakes, fresh and brackish water regions of the Hudson River estuary, and two coastal marine sites. In the Hudson River estuary, the distribution of radiocesium between suspended and dissolved phases in water was found to be a function of salinity. Mean rates of deposition of suspended radiocesium into bottom sediment are calculated from the temporal changes in concentrations of the media, and observed depth distributions in sediment are semi-quantitatively described. Desorption by salt water is identified as the major mechanism for transport of radiocesium from bottom sediment in the lower estuary, and half-times for removal by this mechanism are estimated to be 1.5 to 2.0 years. Suspended-dissolved distributions of radiocesium in water, and depth distributions in sediment are also presented for lake and marine systems. Accumulation of radiocesium by fish is examined in relation to radiocesium distributions in water, sediment, and other biota, and to the chemical characteristics of each ecosystem. Radiocesium dissolved in water was the primary source to the fish in all ecosystems. Sediment inventories of 137 Cs constituted a secondary source which provided as much as 50 percent of the radiocesium in benthic feeding fish in the Hudson River. Dietary intake of 137 Cs is shown to be inversely related to the potassium concentration in the ambient water, and results in an inverse proportionality between the concentration factor in fish and the potassium concentrations in the different freshwater and estuarine ecosystems

  16. Limiting factors in the production of deep microstructures

    Science.gov (United States)

    Tolfree, David W. L.; O'Neill, William; Tunna, Leslie; Sutcliffe, Christopher

    1999-10-01

    Microsystems increasingly require precision deep microstructures that can be cost-effectively designed and manufactured. New products must be able to meet the demands of the rapidly growing markets for microfluidic, micro- optical and micromechanical devices in industrial sectors which include chemicals, pharmaceuticals, biosciences, medicine and food. The realization of such products, first requires an effective process to design and manufacture prototypes. Two process methods used for the fabrication of high aspect-ratio microstructures are based on X-ray beam lithography with electroforming processes and direct micromachining with a frequency multiplied Nd:YAG laser using nanosecond pulse widths. Factors which limit the efficiency and precision obtainable using such processes are important parameters when deciding on the best fabrication method to use. A basic microstructure with narrow channels suitable for a microfluidic mixer have been fabricated using both these techniques and comparisons made of the limitations and suitability of the processes in respect of fast prototyping and manufacture or working devices.

  17. Success factors and limitations of efficient internal communication

    Directory of Open Access Journals (Sweden)

    Dariusz Tworzydło

    2015-03-01

    Full Text Available The article covers the key issues of internal communication within an organization. It highlights the benefits of implementation of transparent communication principles for a company. It identifies objectives and presents selected communication tools. In the article, also guidelines for carrying out research in the context of development of an internal communication strategy can be found. Selected research areas of the process of planning and implementation of strategic assumptions have been presented. Factors limiting effective implementation of an internal communication strategy have been discussed.

  18. Managing Urban Water: Opportunities and Limitations of the Ecosystem Services Framework

    Science.gov (United States)

    Hamel, P.; Keeler, B.; Donahue, M.; Hobbie, S. E.; Finlay, J. C.; Brauman, K. A.; Vogl, A.

    2015-12-01

    Traditionally applied to rural environments, the concept of ES is gaining traction in urban areas, overlapping with a number of existing management frameworks in engineering, policy science, political ecology, or urban planning. Given this overlap, it is legitimate to question the value added by the ES concept, either as a theoretical or practical framework. This is particularly the case for urban water management, where new paradigms in engineering and socio-hydrology are increasingly bringing a social dimension to problem solving. In this talk, I will illustrate key opportunities and limitations of the ES framework with a focus on the service of stormwater retention. Drawing from examples in the Global North and South (including Melbourne, Australia, and Cape Town, South Africa), I will show that the ES lens allows: i) an explicit linkage between beneficiaries and grey and green infrastructure, which improves visibility and credibility of techniques valuing urban nature; ii) an improved understanding of tradeoffs and synergies between services, even in regions with limited environmental or socio-economic data; and iii) the development of powerful visualization techniques, enhancing communication with a broad range of stakeholders. These strengths make ES assessments a powerful tool to raise awareness or assist urban planners in realizing their vision of green cities. However, in cities like Melbourne with high capacity and innovative governance, I will argue that the instrumental use of ES is limited and may even be detrimental; limitations of the ES framework, which include a perceived partiality and vagueness, may be used by detractors to undermine the work of urban planners envisioning a greener city. To conclude the talk, I will present the work that the Natural Capital Project is conducting on the application of the ES concept for global indicators of sustainable development, thereby supporting the monitoring and implementation of urban Sustainable

  19. Climaite - a three factor climate change ecosystem manipulation study: Set up and approaches for data analysis

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Beier, C.; Kappel Schhmidt, I.

    In a new Danish climate change related field scale experiment, CLIMAITE, we are investigating the impacts of individual and multiple simultaneous global changes on ecosystem processes and functioning in a Danish semi natural grassland vegetation dominated by Deschampsia flexuosa and Calluna...... vulgaris. The Climaite experiment involves three global change factors: elevated CO2 (510 ppm), elevated temperature (+ 1-2 C) and altered precipitation (1-1.5 months extended drought in May-July) all compared to ambient conditions in a complete factorial design. The experiment includes six replicates...... initial results from the first treatment year on manipulated and ambient CO2 concentrations and night time temperatures together with plant, soil and ecosystem responses to the treatments (e.g. vegetation surface temperature, soil water content, soil water chemistry, phenology and C sequestration). (www.climaite.dk)...

  20. Factors limiting sulfolane biodegradation in contaminated subarctic aquifer substrate.

    Directory of Open Access Journals (Sweden)

    Christopher P Kasanke

    Full Text Available Sulfolane, a water-soluble organosulfur compound, is used industrially worldwide and is associated with one of the largest contaminated groundwater plumes in the state of Alaska. Despite being widely used, little is understood about the degradation of sulfolane in the environment, especially in cold regions. We conducted aerobic and anaerobic microcosm studies to assess the biological and abiotic sulfolane degradation potential of contaminated subarctic aquifer groundwater and sediment from Interior Alaska. We also investigated the impacts of nutrient limitations and hydrocarbon co-contamination on sulfolane degradation. We found that sulfolane underwent biodegradation aerobically but not anaerobically under nitrate, sulfate, or iron-reducing conditions. No abiotic degradation activity was detectable under either oxic or anoxic conditions. Nutrient addition stimulated sulfolane biodegradation in sediment slurries at high sulfolane concentrations (100 mg L-1, but not at low sulfolane concentrations (500 μg L-1, and nutrient amendments were necessary to stimulate sulfolane biodegradation in incubations containing groundwater only. Hydrocarbon co-contamination retarded aerobic sulfolane biodegradation rates by ~30%. Our study is the first to investigate the sulfolane biodegradation potential of subarctic aquifer substrate and identifies several important factors limiting biodegradation rates. We concluded that oxygen is an important factor limiting natural attenuation of this sulfolane plume, and that nutrient amendments are unlikely to accelerate biodegradation within in the plume, although they may biostimulate degradation in ex situ groundwater treatment applications. Future work should be directed at elucidating the identity of indigenous sulfolane-degrading microorganisms and determining their distribution and potential activity in the environment.

  1. Identifying critical recruitment bottlenecks limiting seedling establishment in a degraded seagrass ecosystem.

    Science.gov (United States)

    Statton, John; Montoya, Leonardo R; Orth, Robert J; Dixon, Kingsley W; Kendrick, Gary A

    2017-11-01

    Identifying early life-stage transitions limiting seagrass recruitment could improve our ability to target demographic processes most responsive to management. Here we determine the magnitude of life-stage transitions along gradients in physical disturbance limiting seedling establishment for the marine angiosperm, Posidonia australis. Transition matrix models and sensitivity analyses were used to identify which transitions were critical for successful seedling establishment during the first year of seed recruitment and projection models were used to predict the most appropriate environments and seeding densities. Total survival probability of seedlings was low (0.001), however, transition probabilities between life-stages differed across the environmental gradients; seedling recruitment was affected by grazing and bioturbation prevailing during the first life-stage transition (1 month), and 4-6 months later during the third life-stage transition when establishing seedlings are physically removed by winter storms. Models projecting population growth from different starting seed densities showed that seeds could replace other more labour intensive and costly methods, such as transplanting adult shoots, if disturbances are moderated sufficiently and if large numbers of seed can be collected in sufficient quantity and delivered to restoration sites efficiently. These outcomes suggest that by improving management of early demographic processes, we could increase recruitment in restoration programs.

  2. Do limiting factors at Alaskan treelines shift with climatic regimes?

    International Nuclear Information System (INIS)

    Ohse, B; Jansen, F; Wilmking, M

    2012-01-01

    Trees at Alaskan treelines are assumed to be limited by temperature and to expand upslope and/or to higher latitudes with global warming. However, recent studies describe negative temperature responses and drought stress of Alaskan treeline trees in recent decades. In this study, we have analyzed the responses of treeline white spruce to temperature and precipitation according to different climatic regimes in Alaska, described as negative (cool) and positive (warm) phases of the Pacific Decadal Oscillation (PDO). We found that in three consecutive phases (positive from 1925–46, negative from 1947–76, and positive again from 1977–98), the growth responses to temperature and precipitation differed markedly. Before 1947, in a phase of warm winters and with summer temperatures being close to the century mean, the trees at most sites responded positively to summer temperature, as one would expect from treeline trees at northern high latitudes. Between 1947 and 1976, a phase of cold winters and average summers, the trees showed similar responses, but a new pattern of negative responses to the summer temperature of the year prior to growth coupled with positive responses to the precipitation in the same year emerged at some sites. As the precipitation was relatively low at those sites, we assume that drought stress might have played a role. However, the climate responses were not uniform but were modified by regional gradients (trees at northern sites responded more often to temperature than trees at southern sites) and local site conditions (forest trees responded more often to precipitation than treeline trees), possibly reflecting differences in energy and water balance across regions and sites, respectively. However, since the shift in the PDO in 1976 from a negative to a positive phase, the trees’ climate–growth responses are much less pronounced and climate seems to have lost its importance as a limiting factor for the growth of treeline white spruce. If

  3. The Role of Vegetation Dynamics on the Soil Water Balance in Water-Limited Ecosystems

    Science.gov (United States)

    Montaldo, N.; Rondena, R.; Albertson, J. D.; Mancini, M.

    2003-12-01

    The structure and function of the vegetation regulates the exchange of mass, energy and momentum across the biosphere-atmosphere interface. Vegetation dynamics are usually neglected, other than seasonal phenology, in land surface models (LSMs). However, changes in vegetation densities, influencing the partitioning of incoming solar energy into sensible and latent heat fluxes, can result in long-term changes in both local and global climates (e.g., precipitation and temperature), which in turn will feedback to affect the vegetation growth. In semi-arid regions, this may result in persistent drought and desertification, with substantial impacts on the human populations of these regions through reduction in agricultural productivity and reduction in quantity and quality of water supply. With an objective of finding a simple vegetation model able to accurately simulate the leaf area index (LAI) dynamics, vegetation models of different level of complexity (e.g., including or not the modeling of the root biomass or the modeling of the dead biomass) are developed and compared. The vegetation dynamics models are coupled to a LSM, with the vegetation models providing the green biomass and the LAI evolution through time, and the LSM using this information in the computation of the land surface fluxes and updating the soil water content in the root-zone. We explore the models on a case study of a water limited grass field in California. Results show that a simple vegetation model that simulates the living aboveground green biomass (i.e., with low parameterization and computational efforts) is able to accurately simulate the LAI. Results also highlight the importance of including the plant growth model in the LSM when studying the climate-soil-vegetation interactions and the impact of watershed management practices on the scarce water resources over moderate to long time scales. The inclusion of the vegetation model in the LSM is demonstrated to be essential for assessing the

  4. Limiting factors in single particle cryo electron tomography

    Directory of Open Access Journals (Sweden)

    Mikhail Kudryashev

    2012-07-01

    Full Text Available Modern methods of cryo electron microscopy and tomography allow visualization of protein nanomachines in their native state at the nanometer scale. Image processing methods including sub-volume averaging applied to repeating macromolecular elements within tomograms allow exploring their structures within the native context of the cell, avoiding the need for protein isolation and purification. Today, many different data acquisition protocols and software solutions are available to researchers to determine average structures of macromolecular complexes and potentially to classify structural intermediates. Here, we list the density maps reported in the literature, and analyze each structure for the chosen instrumental settings, sample conditions, main processing steps, and obtained resolution. We present conclusions that identify factors currently limiting the resolution gained by this approach.

  5. Analysis of chemical factors affecting marine ecosystem around nuclear power plant

    International Nuclear Information System (INIS)

    Chun, Kwan Sik; Choi, Yoon Dong; Chun, Ki Jeong; Kim, Jin Kyu; Jung, Kyeong Chai; Lee, Yeong Keun; Park, Hyo Kook

    1994-06-01

    The ecological data of the coastal area of Youngkwang nuclear power plant from 1987 to 1993 were comprehensively analyzed, and various physical and chemical properties of sea water and sediments were measured. Major factors affecting phytoplankton standing crops were suspended substances, nitrate, and silicate. The contents of iron, chromium, copper, and sulfur in sediments sampled from the discharge channel were slightly higher than those in the other areas. In order to qantify the chemical impacts on marine ecosystem, it is desirable that a systematic survey be made through the whole year cycle to assure the consistency and confidence of the related data. (Author)

  6. Meta-analysis of Digital Consumption in the Contemporary Media Ecosystem: Key Factors and Emotional Implications

    Directory of Open Access Journals (Sweden)

    Javier SERRANO-PUCHE

    2017-01-01

    Full Text Available Two of the characteristic features of contemporary society are the overabundance of information and the speed of communications, which takes place in a scenario marked by people’s hyperconnectivity. This intense use of technology arouses emotions in users and serves as a channel for the expression of affection. Therefore, this paper contains two objectives: (1 To identify general factors that are distinctive of digital consumption in the current media ecosystem and (2 to describe the connotations that said consumption has on human beings’ emotional dimension. The article finally concludes that the development of a critical and conscious media consumption, which is associated with emotional management, is a recommended practice.

  7. Sources, factors, mechanisms and possible solutions to pollutants in marine ecosystems

    International Nuclear Information System (INIS)

    Mostofa, Khan M.G.; Liu, Cong-Qiang; Vione, Davide; Gao, Kunshan; Ogawa, Hiroshi

    2013-01-01

    Algal toxins or red-tide toxins produced during algal blooms are naturally-derived toxic emerging contaminants (ECs) that may kill organisms, including humans, through contaminated fish or seafood. Other ECs produced either naturally or anthropogenically ultimately flow into marine waters. Pharmaceuticals are also an important pollution source, mostly due to overproduction and incorrect disposal. Ship breaking and recycle industries (SBRIs) can also release various pollutants and substantially deteriorate habitats and marine biodiversity. Overfishing is significantly increasing due to the global food crisis, caused by an increasing world population. Organic matter (OM) pollution and global warming (GW) are key factors that exacerbate these challenges (e.g. algal blooms), to which acidification in marine waters should be added as well. Sources, factors, mechanisms and possible remedial measures of these challenges to marine ecosystems are discussed, including their eventual impact on all forms of life including humans. -- Review of sources, factors, mechanisms and possible remedial measures of key pollutants (contaminants, toxins, ship breaking, overfishing) in marine ecosystems

  8. Identifying the principal driving factors of water ecosystem dependence and the corresponding indicator species in a pilot City, China

    Science.gov (United States)

    Zhao, C. S.; Shao, N. F.; Yang, S. T.; Xiang, H.; Lou, H. Z.; Sun, Y.; Yang, Z. Y.; Zhang, Y.; Yu, X. Y.; Zhang, C. B.; Yu, Q.

    2018-01-01

    The world's aquatic ecosystems yield numerous vital services, which are essential to human existence but have deteriorated seriously in recent years. By studying the mechanisms of interaction between ecosystems and habitat processes, the constraining factors can be identified, and this knowledge can be used to improve the success rate of ecological restoration initiatives. At present, there is insufficient data on the link between hydrological, water quality factors and the changes in the structure of aquatic communities to allow any meaningful study of driving factors of aquatic ecosystems. In this study, the typical monitoring stations were selected by fuzzy clustering analysis based on the spatial and temporal distribution characteristics of water ecology in Jinan City, the first pilot city for the construction of civilized aquatic ecosystems in China. The dominant species identification model was used to identify the dominant species of the aquatic community. The driving effect of hydrological and water quality factors on dominant species was analyzed by Canonical Correspondence Analysis. Then, the principal factors of aquatic ecosystem dependence were selected. The results showed that there were 10 typical monitoring stations out of 59 monitoring sites, which were representative of aquatic ecosystems, 9 dominant fish species, and 20 dominant invertebrate species. The selection of factors for aquatic ecosystem dependence in Jinan were highly influenced by its regional conditions. Chemical environmental parameters influence the temporal and spatial variation of invertebrate much more than that of fish in Jinan City. However, the methodologies coupling typical monitoring stations selection, dominant species determination and driving factors identification were certified to be a cost-effective way, which can provide in-deep theoretical and technical directions for the restoration of aquatic ecosystems elsewhere.

  9. Understanding the Factors Influencing Nonindustrial Private Forest Landowner Interest in Supplying Ecosystem Services in Cumberland Plateau, Tennessee

    Directory of Open Access Journals (Sweden)

    Nana Tian

    2015-11-01

    Full Text Available Private forests provide a range of ecosystem services for society including provisioning, regulating, cultural, and supporting services. Sustaining the supply of such services depends on the interest of nonindustrial private forest (NIPF landowners in managing their forests for such services. Assessing factors that influence NIPF landowner intentions would be useful in identifying potential suppliers of ecosystem services and in designing and implementing outreach and education programs to elevate the interests of less interested landowners. Using data collected from a mail survey of NIPF landowners on the Cumberland Plateau of Tennessee, this study examined how landowner interest in supplying ecosystem services was influenced by socio-demographic characteristics, economic and market factors, land management objectives, and ownership motivations. To that end, a multivariate logistic regression model was employed to analyze the supply of three types of ecosystem services: carbon storage (regulating service, water quality (provisioning service, and aesthetics (cultural service. Results revealed that landowner interest in managing forests for ecosystem services were significantly related to socio-demographic factors, management and ownership characteristics, and availability of financial incentives. These findings will improve the understanding of the market segment of landowners as related to ecosystem services. The findings may facilitate the development of market protocols and outreach programs that promote payments for ecosystem services in Tennessee and elsewhere.

  10. Merits and Limits of Ecosystem Protection for Conserving Wild Salmon in a Northern Coastal British Columbia River

    Directory of Open Access Journals (Sweden)

    Aaron C. Hill

    2010-06-01

    Full Text Available Loss and degradation of freshwater habitat reduces the ability of wild salmon populations to endure other anthropogenic stressors such as climate change, harvest, and interactions with artificially propagated fishes. Preservation of pristine salmon rivers has thus been advocated as a cost-effective way of sustaining wild Pacific salmon populations. We examine the value of freshwater habitat protection in conserving salmon and fostering resilience in the Kitlope watershed in northern coastal British Columbia - a large (3186 km2 and undeveloped temperate rainforest ecosystem with legislated protected status. In comparison with other pristine Pacific Rim salmon rivers we studied, the Kitlope is characterized by abundant and complex habitats for salmon that should contribute to high resilience. However, biological productivity in this system is constrained by naturally cold, light limited, ultra-oligotrophic growing conditions; and the mean (± SD density of river-rearing salmonids is currently low (0.32 ± 0.27 fish per square meter; n = 36 compared to our other four study rivers (grand mean = 2.55 ± 2.98 fish per square meter; n = 224. Existing data and traditional ecological knowledge suggest that current returns of adult salmon to the Kitlope, particularly sockeye, are declining or depressed relative to historic levels. This poor stock status - presumably owing to unfavorable conditions in the marine environment and ongoing harvest in coastal mixed-stock fisheries - reduces the salmon-mediated transfer of marine-derived nutrients and energy to the system's nutrient-poor aquatic and terrestrial food webs. In fact, Kitlope Lake sediments and riparian tree leaves had marine nitrogen signatures (δ15N among the lowest recorded in a salmon ecosystem. The protection of the Kitlope watershed is undoubtedly a conservation success story. However, "salmon strongholds" of pristine watersheds may not adequately sustain salmon populations and foster

  11. Tissular senescence and modifications of oral ecosystem in the elderly: risk factors for mucosal pathologies.

    Science.gov (United States)

    Bodineau, Agnès; Folliguet, Marysette; Séguier, Sylvie

    2009-07-01

    The aim of this present review is to describe the pathogenesis and mechanisms behind mucosal pathologies in the elderly including a description of the risk factors for these pathologies. The oral cavity - and particularly oral mucosae - is exposed to many stresses as well as physical, chemical, thermic and pathogenic agents. In the elderly, mucosae are less resistant to the insults, and this increases the occurrence of diseases. Several factors contribute to the prevalence of mucosal pathologies with aging. There are two categories: intrinsic factors linked to the senescence of the tissues and functions, and extrinsic factors related to the older people general health status. The intrinsic factors are: 1) mucosal senescence which induces fragility 2) immunosenescence which causes a decrease in the host response against micro-organisms and an increase in the autoimmune diseases and 3) senescence of salivary glands and reduction of the saliva protective function. Furthermore, there are extrinsic factors which contribute to change the oral ecosystem during aging, such as polypathologies and polymedications, malnutrition, degradation of oral hygiene, pathogen proliferation (mainly bacteria and Candida species) and old or ill-fitted removable dentures. In the elderly several diseases occur on the oral mucosae: inflammation, bacterial infections or candidiasis, ulcerations, autoimmune dermatosis, tumoral processes. This review describes some common oral mucosal pathologies in the older people, which illustrate the impact of different risk factors described in the first part.

  12. Sources, factors, mechanisms and possible solutions to pollutants in marine ecosystems.

    Science.gov (United States)

    Mostofa, Khan M G; Liu, Cong-Qiang; Vione, Davide; Gao, Kunshan; Ogawa, Hiroshi

    2013-11-01

    Algal toxins or red-tide toxins produced during algal blooms are naturally-derived toxic emerging contaminants (ECs) that may kill organisms, including humans, through contaminated fish or seafood. Other ECs produced either naturally or anthropogenically ultimately flow into marine waters. Pharmaceuticals are also an important pollution source, mostly due to overproduction and incorrect disposal. Ship breaking and recycle industries (SBRIs) can also release various pollutants and substantially deteriorate habitats and marine biodiversity. Overfishing is significantly increasing due to the global food crisis, caused by an increasing world population. Organic matter (OM) pollution and global warming (GW) are key factors that exacerbate these challenges (e.g. algal blooms), to which acidification in marine waters should be added as well. Sources, factors, mechanisms and possible remedial measures of these challenges to marine ecosystems are discussed, including their eventual impact on all forms of life including humans. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Factorization and hadronic B decays in the heavy quark limit

    Science.gov (United States)

    Cottingham, W. N.; Whittingham, I. B.; de Groot, N.; Wilson, F.

    2002-11-01

    Recent theoretical investigations (Beneke M et al 1999 Phys. Rev. Lett. 83 1914) of two-body hadronic B decays have provided justification, at least to order αs, for the use of the factorization ansatz to evaluate the B decay matrix elements provided the decay meson containing the spectator quark is not heavy. Although data is now available on many charmless two-body B decay channels, it is so far not very precise with systematic and statistical errors in total of the order of 25% or greater. Analyses have been made on ππ and πK channels with somewhat contradictory results (Beneke M et al 2001 Nucl. Phys. B 606 245; Ciuchini M et al 2001 Preprint hep-ph/0110022). We take an overview of these channels and of other channels containing vector mesons. Because factorization involves many poorly known soft QCD parameters, and because of the imprecision of the current data, we present simplified formulae for a wide range of B decays into the lowest mass pseudoscalar and vector mesons. These formulae, valid in the heavy quark limit, involve a reduced set of soft QCD parameters and, although resulting in some loss of accuracy, should still provide an adequate and transparent tool with which to confront data for some time to come. Finally we confront these formulae with the data on 19 channels. We find a plausible set of soft QCD parameters that, apart from three pseudoscalar vector channels, fit the branching ratios and the recently measured value of sin(2β) quite well.

  14. Effects of UV radiation on aquatic ecosystems and interactions with other environmental factors.

    Science.gov (United States)

    Häder, Donat-P; Williamson, Craig E; Wängberg, Sten-Åke; Rautio, Milla; Rose, Kevin C; Gao, Kunshan; Helbling, E Walter; Sinha, Rajeshwar P; Worrest, Robert

    2015-01-01

    the ability of many marine organisms to form UV-absorbing exoskeletons. Many aquatic organisms use adaptive strategies to mitigate the effects of solar UV-B radiation (280-315 nm), including vertical migration, crust formation, synthesis of UV-absorbing substances, and enzymatic and non-enzymatic quenching of ROS. Whether or not genetic adaptation to changes in the abiotic factors plays a role in mitigating stress and damage has not been determined. This assessment addresses how our knowledge of the interactive effects of UV radiation and climate change factors on aquatic ecosystems has advanced in the past four years.

  15. FACTORS LIMITING THE EFFECTIVENESS OF INTESTINAL PARASITOSES’ PHARMACOTHERAPY

    Directory of Open Access Journals (Sweden)

    Kalina Stoyanova

    2017-10-01

    Full Text Available The effective etiological antiparasitic treatment fulfils two major goals - to cure the infected patient and to terminate its role as an epidemiologically relevant source of infection. The purpose of this study is to evaluate the effectiveness of the pharmacotherapy against the most common intestinal helminthic and protozoal infections diagnosed in Varna region. Material and Methods: 879 patients with laboratory-confirmed intestinal parasitoses were treated etiologically with the established anthelminthic and antiprotozoal agents. Mandatory and active post-treatment laboratory monitoring served as the basis for the assessment of the therapy effectiveness. Results: Enterobiasis has the highest prevalence of the intestinal parasitic infections with estimated treatment success of 94,7% at the end of the mandatory period and nearly 100% at the end of our monitoring. The significantly greater rate of relapses was registered among the patients with the two most common protozoal invasions – Giardiasis (9,5% and Blastocystosis (6,7 %. Our analysis established that the main factors limiting the effective antiparasitic pharmacotherapy are extraneous, i.e. independent of the pharmacological properties of the agent or parasite’s biology. The most prominent reasons for therapy failure are poor or missing compliance to the therapy regimen, inadequate form or dosage of the medication, unrecognized source of (reinvasion, etc. In conclusion, the collaboration between the general practitioners, clinical parasitologists and respectively the patients themselves is crucial for achieving an effective therapy and the resultant control of the intestinal parasitoses.

  16. Is iron a limiting factor of Nodularia spumigena blooms?

    Directory of Open Access Journals (Sweden)

    Lidia Paczuska

    2003-12-01

    Full Text Available It is well known that a deficiency of iron, a trace element essential to every living organism, limits the growth of algae and cyanobacteria. Nodularia spumigena Mertens is a blue-green algae species inhabiting the Baltic region that often forms toxic blooms.     The aim of the study was to assess the growth of the toxic cyanobacteria with respect to iron bioavailability. The measured growth parameters were the numbers of cells (optical density, chlorophyll a and pheopigment a concentrations. The iron concentrations used ranged from 10-7 to 10-4 mol dm-3. Under iron stress conditions (<5 × 10-7 mol dm-3, growth inhibition, gradual pigment decay and cell mortality were observed. However, enriching the medium with complexing factors like citric acid and EDTA significantly stimulated the growth rate and chlorophyll a production. The citric acid - EDTA - Fe (5 × 10-7 mol dm-3 complex was demonstrably effective in stimulating the rate of cell division. Starting with 10-6 mol dm-3, the higher the iron(III concentration used in the media, the more intensive the growth of the cyanobacteria populations. This was most rapid in the presence of high iron concentrations (10-4 mol dm-3, regardless of the presence of complexing agents.     It appears that the growth of toxic cyanobacteria N. spumigena, and thus also its ability to form blooms, may well depend on iron availability in the environment.

  17. Factors which could limit the nuclear fuel cycle development

    International Nuclear Information System (INIS)

    Pecqueur, M.; Barre, B.

    1977-01-01

    The nuclear fuel cycle is a most important industry for the energy future of the world. It has also a leading part as regards the physical continuity of energy supply of the countries engaged in the nuclear field. The development of this industry is subject to the economic or political constraints involved by the availability of raw materials, technologies or production means. The various limiting factors which could affect the different stages of the fuel cycle are linked with the technical, economic and financial aspects, with the impact on the environment, nuclear safety, risks of non-pacific uses and proliferation of arms. Interesting to note is also the correlation between the fuel cycle development and the problems of energy independence and security of nuclear programs. As a conclusion, the nuclear fuel cycle industry is confronted to difficulties due to its extremely rapid growth (doubling time 5 years) which only few heavy industries have encountered for long periods. It is more over submitted to the political and safety constraints always linked with nuclear matters. The task is therefore a difficult one. But the objective is worth-while since it is a condition to the development of nuclear industry [fr

  18. Interacting factors driving a major loss of large trees with cavities in a forest ecosystem.

    Directory of Open Access Journals (Sweden)

    David B Lindenmayer

    Full Text Available Large trees with cavities provide critical ecological functions in forests worldwide, including vital nesting and denning resources for many species. However, many ecosystems are experiencing increasingly rapid loss of large trees or a failure to recruit new large trees or both. We quantify this problem in a globally iconic ecosystem in southeastern Australia--forests dominated by the world's tallest angiosperms, Mountain Ash (Eucalyptus regnans. Tree, stand and landscape-level factors influencing the death and collapse of large living cavity trees and the decay and collapse of dead trees with cavities are documented using a suite of long-term datasets gathered between 1983 and 2011. The historical rate of tree mortality on unburned sites between 1997 and 2011 was >14% with a mortality spike in the driest period (2006-2009. Following a major wildfire in 2009, 79% of large living trees with cavities died and 57-100% of large dead trees were destroyed on burned sites. Repeated measurements between 1997 and 2011 revealed no recruitment of any new large trees with cavities on any of our unburned or burned sites. Transition probability matrices of large trees with cavities through increasingly decayed condition states projects a severe shortage of large trees with cavities by 2039 that will continue until at least 2067. This large cavity tree crisis in Mountain Ash forests is a product of: (1 the prolonged time required (>120 years for initiation of cavities; and (2 repeated past wildfires and widespread logging operations. These latter factors have resulted in all landscapes being dominated by stands ≤72 years and just 1.16% of forest being unburned and unlogged. We discuss how the features that make Mountain Ash forests vulnerable to a decline in large tree abundance are shared with many forest types worldwide.

  19. Activity limitations and factors influencing functional outcome of ...

    African Journals Online (AJOL)

    Results: The mean Barthel Index scores on admission and at discharge were 58.85 and 81.59 respectively. A significant improvement was noted in the ... It further underscores the administration of a functional rating scale on admission in order to aggressively manage activity limitations. Key words: stroke, activity limitations, ...

  20. Country-wide assessment of estuary health: An approach for integrating pressures and ecosystem response in a data limited environment

    CSIR Research Space (South Africa)

    Van Niekerk, L

    2013-09-01

    Full Text Available Population and development pressures increase the need for proactive strategic management on a regional or country-wide scale - reactively protecting ecosystems on an estuary-by-estuary basis against multiple pressures is ‘resource hungry...

  1. Factors Limiting Vocational Agriculture Student Participation in Supervised Occupational Experience Programs in Nebraska.

    Science.gov (United States)

    Foster, Richard M.

    1986-01-01

    In this study, economic factors were consistently rated as important considerations in limited student participation in supervised farm practice in Nebraska high schools. It was indicated that administrative support was the least limiting factor for student participation. (CT)

  2. Growing season length as a key factor of cumulative net ecosystem exchange over the pine forest ecosystems in Europe

    Czech Academy of Sciences Publication Activity Database

    Danielewska, A.; Urbaniak, M.; Olejnik, Janusz

    2015-01-01

    Roč. 29, č. 2 (2015), s. 129-135 ISSN 0236-8722 Institutional support: RVO:67179843 Keywords : forest * carbon dioxide * eddy covariance * growing season length Subject RIV: EH - Ecology, Behaviour Impact factor: 1.067, year: 2015

  3. Impact of environmental factors and biological soil crust types on soil respiration in a desert ecosystem.

    Science.gov (United States)

    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93 ± 0.43 µmol m-2 s-1) and the lowest values in algae-crusted soil (0.73 ± 0.31 µmol m-2 s-1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m-3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level.

  4. The adaptation rate of terrestrial ecosystems as a critical factor in global climate dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Fuessler, J.S.; Gassmann, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    A conceptual climate model describing regional two-way atmosphere-vegetation interaction has been extended by a simple qualitative scheme of ecosystem adaptation to drought stress. The results of this explorative study indicate that the role of terrestrial vegetation under different forcing scenarios depends crucially on the rate of the ecosystems adaptation to drought stress. The faster the adaptation of important ecosystems such as forests the better global climate is protected from abrupt climate changes. (author) 1 fig., 3 refs.

  5. Activity limitations and factors influencing functional outcome of ...

    African Journals Online (AJOL)

    EB

    2013-09-03

    Sep 3, 2013 ... It further underscores the administration of a functional rating scale on admission in order to aggressively manage activity limitations. .... rating scale (presented with intervals of 5 points) of this tool allows for the measurement of the ..... function and life satisfaction after stroke. Journal of the American Heart ...

  6. Limiting factors of exercise performance 1 year after lung transplantation

    NARCIS (Netherlands)

    Reinsma, G. D.; ten Hacken, N. H. T.; Grevink, R. G.; van der Bij, W.; Koer, G. H.; van Weert, E.

    2006-01-01

    Background: After lung transplantation (LTx). exercise capacity frequently remains limited, despite significantly improved pulmonary function. The aim of this study was to evaluate maximal exercise capacity and peripheral muscle force before and 1 year after LTx, and to determine whether peripheral

  7. Limiter

    Science.gov (United States)

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  8. Linking the spatial patterns of organisms and abiotic factors to ecosystem function and management: insights from semi-arid environments

    Directory of Open Access Journals (Sweden)

    F. T. Maestre

    2006-12-01

    Full Text Available Numerous theoretical and modeling studies have demonstrated the ecological significance of the spatial patterning of organisms on ecosystem functioning and dynamics. However, there is a paucity of empirical evidence that quantitatively shows how changes in the spatial patterns of the organisms forming biotic communities are directly related to ecosystem structure and functioning. In this article, I review a series of experiments and observational studies conducted in semi-arid environments from Spain (degraded calcareous shrubland, steppes dominated by Stipa tenacissima, and gypsum shrublands to: 1 evaluate whether the spatial patterns of the dominant biotic elements in the community are linked to ecosystem structure and functioning, and 2 test if these patterns, and those of abiotic factors, can be used to improve ecosystem restoration. In the semiarid steppes we found a significant positive relationship between the spatial pattern of the perennial plant community and: i the water status of S. tenacissima and ii perennial species richness and diversity. Experimental plantings conducted in these steppes showed that S. tenacissima facilitated the establishment of shrub seedlings, albeit the magnitude and direction of this effect was dependent on rainfall conditions during the first yr after planting. In the gypsum shrubland, a significant, direct relationship between the spatial pattern of the biological soil crusts and surrogates of ecosystem functioning (soil bulk density and respiration was found. In a degraded shrubland with very low vegetation cover, the survival of an introduced population of the shrub Pistacia lentiscus showed marked spatial patterns, which were related to the spatial patterns of soil properties such as soil compaction and sand content. These results provide empirical evidence on the importance of spatial patterns for maintaining ecosystem structure and functioning in semi-arid ecosystems

  9. Limited ankle dorsiflexion: a predisposing factor to Morbus Osgood Schlatter?

    Science.gov (United States)

    Sarcević, Zoran

    2008-08-01

    Quadriceps femoris muscle contracts eccentrically during the stance phase of running till the beginning of propulsion when the knee reaches the highest level of flexion. Limited dorsiflexion in the ankle joint is associated with a compensatory increased knee flexion, tibial inversion, and foot pronation during the stance phase of running. Theoretically, these compensatory mechanisms might cause increased stress on the quadriceps femoris muscle attachment to the tuberositas tibia. This study is aimed at evaluating a possible relationship between limited dorsiflexion of the ankle and the occurrence of Morbus Osgood Schlatter (MOS) in sports-active children. Forty-five children, including 40 boys (mean age 13 years, range 11-14) and 5 girls (mean age 12 years, range 10-12) with the clinical diagnosis of MOS, were studied. Dorsiflexion angle (DFA) of less than 10 degrees was found in 37 boys, whereas 3 of them had a DFA of more than 10 degrees . All five girls had a DFA of less than 10 degrees . In conclusion, limited dorsiflexion of the ankle joint might be of significant importance for MOS. Further studies are warranted to evaluate the cause-effect relationship.

  10. Linking demand and supply factors in identifying cultural ecosystem services of urban green infrastructures

    NARCIS (Netherlands)

    Hegetschweiler, K.T.; Vries, de Sjerp; Arnberger, Arne; Bell, Simon; Brennan, Michael; Siter, Nathan; Olafsson, Anton Stahl; Voigt, Annette; Hunziker, Marcel

    2017-01-01

    Urban green infrastructure provides a number of cultural ecosystem services that are greatly appreciated by the public. In order to benefit from these services, actual contact with the respective ecosystem is often required. Furthermore, the type of services offered depend on the physical

  11. Country-wide assessment of estuary health: An approach for integrating pressures and ecosystem response in a data limited environment

    Science.gov (United States)

    Van Niekerk, L.; Adams, J. B.; Bate, G. C.; Forbes, A. T.; Forbes, N. T.; Huizinga, P.; Lamberth, S. J.; MacKay, C. F.; Petersen, C.; Taljaard, S.; Weerts, S. P.; Whitfield, A. K.; Wooldridge, T. H.

    2013-09-01

    Population and development pressures increase the need for proactive strategic management on a regional or country-wide scale - reactively protecting ecosystems on an estuary-by-estuary basis against multiple pressures is 'resource hungry' and not feasible. Proactive management requires a strategic assessment of health so that the most suitable return on investment can be made. A country-wide assessment of the nearly 300 functional South African estuaries examined both key pressures (freshwater inflow modification, water quality, artificial breaching of temporarily open/closed systems, habitat modification and exploitation of living resources) and health state. The method used to assess the type and level of the different pressures, as well as the ecological health status of a large number of estuaries in a data limited environment is described in this paper. Key pressures and the ecological condition of estuaries on a national scale are summarised. The template may also be used to provide guidance to coastal researchers attempting to inform management in other developing countries. The assessment was primarily aimed at decision makers both inside and outside the biodiversity sector. A key starting point was to delineate spatially the estuary functional zone (area) for every system. In addition, available data on pressures impacting estuaries on a national scale were collated. A desktop national health assessment, based on an Estuarine Health Index developed for South African ecological water requirement studies, was then applied systematically. National experts, all familiar with the index evaluated the estuaries in their region. Individual estuarine health assessment scores were then translated into health categories that reflect the overall status of South Africa's estuaries. The results showed that estuaries in the warm-temperate biogeographical zone are healthier than those in the cool-temperate and subtropical zones, largely reflecting the country

  12. Six Sigma: Problems, Limitations, Critical Success Factors and Future Prospects

    Directory of Open Access Journals (Sweden)

    Paulo Mazieiro Pohlmann

    2015-12-01

    Full Text Available Six Sigma is a business strategy based on objective decision making and problem solving in order to achieve, maintain and maximize business success through understanding and meeting the needs of customers. The visualization of this methodology as a powerful tool in reducing variability and improving quality led to the interest in performing this bibliographical study, whose purpose was to assess the critical success factors and future prospects of this managerial system. A survey was conducted in order to discover the main critical success factors of the implementation of the methodology in organizations, among which stood out the proper selection of projects, connecting the project with the business strategy, customer focus, financial, human and infrastructure resources, the involvement of senior management, professional training, and cultural change.

  13. Factors Limiting Complete Tumor Ablation by Radiofrequency Ablation

    International Nuclear Information System (INIS)

    Paulet, Erwan; Aube, Christophe; Pessaux, Patrick; Lebigot, Jerome; Lhermitte, Emilie; Oberti, Frederic; Ponthieux, Anne; Cales, Paul; Ridereau-Zins, Catherine; Pereira, Philippe L.

    2008-01-01

    The purpose of this study was to determine radiological or physical factors to predict the risk of residual mass or local recurrence of primary and secondary hepatic tumors treated by radiofrequency ablation (RFA). Eighty-two patients, with 146 lesions (80 hepatocellular carcinomas, 66 metastases), were treated by RFA. Morphological parameters of the lesions included size, location, number, ultrasound echogenicity, computed tomography density, and magnetic resonance signal intensity were obtained before and after treatment. Parameters of the generator were recorded during radiofrequency application. The recurrence-free group was statistically compared to the recurrence and residual mass groups on all these parameters. Twenty residual masses were detected. Twenty-nine lesions recurred after a mean follow-up of 18 months. Size was a predictive parameter. Patients' sex and age and the echogenicity and density of lesions were significantly different for the recurrence and residual mass groups compared to the recurrence-free group (p < 0.05). The presence of an enhanced ring on the magnetic resonance control was more frequent in the recurrence and residual mass groups. In the group of patients with residual lesions, analysis of physical parameters showed a significant increase (p < 0.05) in the time necessary for the temperature to rise. In conclusion, this study confirms risk factors of recurrence such as the size of the tumor and emphasizes other factors such as a posttreatment enhanced ring and an increase in the time necessary for the rise in temperature. These factors should be taken into consideration when performing RFA and during follow-up

  14. Evidence of Facilitation Cascade Processes as Drivers of Successional Patterns of Ecosystem Engineers at the Upper Altitudinal Limit of the Dry Puna.

    Directory of Open Access Journals (Sweden)

    Luca Malatesta

    Full Text Available Facilitation processes constitute basic elements of vegetation dynamics in harsh systems. Recent studies in tropical alpine environments demonstrated how pioneer plant species defined as "ecosystem engineers" are capable of enhancing landscape-level richness by adding new species to the community through the modification of microhabitats, and also provided hints about the alternation of different ecosystem engineers over time. Nevertheless, most of the existing works analysed different ecosystem engineers separately, without considering the interaction of different ecosystem engineers. Focusing on the altitudinal limit of Peruvian Dry Puna vegetation, we hypothesized that positive interactions structure plant communities by facilitation cascades involving different ecosystem engineers, determining the evolution of the microhabitat patches in terms of abiotic resources and beneficiary species hosted. To analyze successional mechanisms, we used a "space-for-time" substitution to account for changes over time, and analyzed data on soil texture, composition, and temperature, facilitated species and their interaction with nurse species, and surface area of engineered patches by means of chemical analyses, indicator species analysis, and rarefaction curves. A successional process, resulting from the dynamic interaction of different ecosystem engineers, which determined a progressive amelioration of soil conditions (e.g. nitrogen and organic matter content, and temperature, was the main driver of species assemblage at the community scale, enhancing species richness. Cushion plants act as pioneers, by starting the successional processes that continue with shrubs and tussocks. Tussock grasses have sometimes been found to be capable of creating microhabitat patches independently. The dynamics of species assemblage seem to follow the nested assemblage mechanism, in which the first foundation species to colonize a habitat provides a novel substrate for

  15. Evidence of Facilitation Cascade Processes as Drivers of Successional Patterns of Ecosystem Engineers at the Upper Altitudinal Limit of the Dry Puna.

    Science.gov (United States)

    Malatesta, Luca; Tardella, Federico Maria; Piermarteri, Karina; Catorci, Andrea

    2016-01-01

    Facilitation processes constitute basic elements of vegetation dynamics in harsh systems. Recent studies in tropical alpine environments demonstrated how pioneer plant species defined as "ecosystem engineers" are capable of enhancing landscape-level richness by adding new species to the community through the modification of microhabitats, and also provided hints about the alternation of different ecosystem engineers over time. Nevertheless, most of the existing works analysed different ecosystem engineers separately, without considering the interaction of different ecosystem engineers. Focusing on the altitudinal limit of Peruvian Dry Puna vegetation, we hypothesized that positive interactions structure plant communities by facilitation cascades involving different ecosystem engineers, determining the evolution of the microhabitat patches in terms of abiotic resources and beneficiary species hosted. To analyze successional mechanisms, we used a "space-for-time" substitution to account for changes over time, and analyzed data on soil texture, composition, and temperature, facilitated species and their interaction with nurse species, and surface area of engineered patches by means of chemical analyses, indicator species analysis, and rarefaction curves. A successional process, resulting from the dynamic interaction of different ecosystem engineers, which determined a progressive amelioration of soil conditions (e.g. nitrogen and organic matter content, and temperature), was the main driver of species assemblage at the community scale, enhancing species richness. Cushion plants act as pioneers, by starting the successional processes that continue with shrubs and tussocks. Tussock grasses have sometimes been found to be capable of creating microhabitat patches independently. The dynamics of species assemblage seem to follow the nested assemblage mechanism, in which the first foundation species to colonize a habitat provides a novel substrate for colonization by other

  16. Explanatory factors of female entrepreneurship and limiting elements

    Directory of Open Access Journals (Sweden)

    Carmina Pérez-Pérez

    2016-06-01

    Full Text Available Researches on entrepreneurship from a gender perspective reveal significant differences not only between the levels of participation of men and women in business, but also between the orientations, motives and business opportunities for both. Based on this fact, the following investigation is performed, whose objective is twofold: firstly, to know what are the aspects that influence the entrepreneurship of women and secondly, to identify what factors determine and/or difficult the creation and development of business that they undertake. To achieve both, it is reviewed, first, the literature on this subject and, second, are exposed the main results of the qualitative analysis with Atlas.ti from interviews with a group of Spanish entrepreneurs.

  17. Limiting factors to oxygen transport on Mount Everest.

    Science.gov (United States)

    Cerretelli, P

    1976-05-01

    The effect of a sudden increase of the inspired oxygen tension on the maximal aerobic performance was studied on 23 subjects acclimated to high altitude (5,350-8,848 m above sea level) in the course of a 4-mo expedition to Mt. Everest. Inhalation of 100% O2 at 390 mmHg or a rapid descent (20 min) by helicopter to 2,850 m (Pio2 = 117 mmHg) raised maximal oxygen consumption (Vo2 max) from an average 0.7 of the control sea-level value, respectively, to 0.92 and 0.97. The failure of acclimated subjects to increase markedly or even to resume the preexisting sea-level Vo2mxa while breathing O2 in the presence of a 40% increase of blood Hb concentration and of a limited reduction of maximal cardiac output (Qmax), is attributed to changes in the peripheral circulation. These may consist of a) a hindrance of O2 diffusion due to erythrocytes packing secondary to increased hematocrit (Hct up to 70%); b) a bypass of arterial blood from the high-resistance working areas of the body aimed at reducing the load on the heart caused by increased blood viscosity. A 11.6% increase above normal controls of Hb concentration still found in 13 subjects 25 days after leaving altitude does not increase significantly maximum O2 consumption.

  18. Terrestrial ecosystems, increased solar ultraviolet radiation, and interactions with other climate change factors.

    Science.gov (United States)

    Caldwell, M M; Bornman, J F; Ballaré, C L; Flint, S D; Kulandaivelu, G

    2007-03-01

    as growth, DNA damage, oxidative damage and induction of changes in secondary chemicals. Thus, use of a single BSWF for plant or ecosystem response is not appropriate. This brief review emphasizes progress since the previous report toward the understanding of solar ultraviolet radiation effects on terrestrial systems as it relates to ozone column reduction and the interaction of climate change factors.

  19. Ecosystem Resilience and Limitations Revealed by Soil Bacterial Community Dynamics in a Bark Beetle-Impacted Forest

    Directory of Open Access Journals (Sweden)

    Kristin M. Mikkelson

    2017-12-01

    Full Text Available Forested ecosystems throughout the world are experiencing increases in the incidence and magnitude of insect-induced tree mortality with large ecologic ramifications. Interestingly, correlations between water quality and the extent of tree mortality in Colorado montane ecosystems suggest compensatory effects from adjacent live vegetation that mute responses in less severely impacted forests. To this end, we investigated whether the composition of the soil bacterial community and associated functionality beneath beetle-killed lodgepole pine was influenced by the extent of surrounding tree mortality. The most pronounced changes were observed in the potentially active bacterial community, where alpha diversity increased in concert with surrounding tree mortality until mortality exceeded a tipping point of ~30 to 40%, after which diversity stabilized and decreased. Community structure also clustered in association with the extent of surrounding tree mortality with compositional trends best explained by differences in NH4+ concentrations and C/N ratios. C/N ratios, which were lower in soils under beetle-killed trees, further correlated with the relative abundance of putative nitrifiers and exoenzyme activity. Collectively, the response of soil microorganisms that drive heterotrophic respiration and decay supports observations of broader macroscale threshold effects on water quality in heavily infested forests and could be utilized as a predictive mechanism during analogous ecosystem disruptions.

  20. Factors limiting the recovery of boreal toads (Bufo b. boreas)

    Science.gov (United States)

    Carey, C.; Corn, P.S.; Jones, M.S.; Livo, L.J.; Muths, E.; Loeffler, C.W.; Lannoo, M.

    2005-01-01

    early 1990s, however, indicated that the toads were still present in only one of 377 historical sites in parts of western Colorado (Hammerson, 1992) and in about 17% of previously known sites in the Colorado Front Range (Corn et al., 1989). Once common in Rocky Mountain National Park, boreal toads are now found at only seven localities, with just two or three of these populations likely to be reproducing successfully each year (Corn et al., 1997). Intensive surveys by the Boreal Toad Recovery Team since 1995 have found about 50 breeding sites comprising 25 distinct populations within Colorado (Loeffler, unpublished data). Of these populations, most are small (fewer than five egg clutches laid per year) and may not survive over the long term. Efforts to restore population sizes and expand the geographical distribution of boreal toads in the southern Rocky Mountains have involved considerable person-hours and financial commitments. Special care has been taken to protect habitats and, when feasible, to improve sites where breeding populations currently exist. However, initial attempts to repatriate these toads in historic habitats in which boreal toads were present before 1975 have generally proven unsuccessful (Carey, unpublished data; Muths et al., 2003). It is too early to determine if recent repatriations will establish breeding populations (Scherff-Norris, 1999), but these efforts will likely continue. Despite the best human intentions and efforts, the recovery of former population sizes and the historical distribution of boreal toads will greatly depend on its own life history characteristics. However, as we will review in this paper, environmental factors affect many life history attributes in a manner that poses serious obstacles for recovery.

  1. Soil Water Balance and Vegetation Dynamics in two Water-limited Mediterranean Ecosystem on Sardinia under past and future climate change

    Science.gov (United States)

    Corona, R.; Montaldo, N.; Albertson, J. D.

    2016-12-01

    Water limited conditions strongly impacts soil and vegetation dynamics in Mediterranean regions, which are commonly heterogeneous ecosystems, characterized by inter-annual rainfall variability, topography variability and contrasting plant functional types (PFTs) competing for water use. Historical human influences (e.g., deforestation, urbanization) further altered these ecosystems. Sardinia island is a representative region of Mediterranean ecosystems. It is low urbanized except some plan areas close to the main cities where main agricultural activities are concentrated. Two contrasting case study sites are within the Flumendosa river basin (1700 km2). The first site is a typical grassland on an alluvial plan valley (soil depth > 2m) while the second is a patchy mixture of Mediterranean vegetation species (mainly wild olive trees and C3 herbaceous) that grow in a soil bounded from below by a rocky layer of basalt, partially fractured (soil depth 15 - 40 cm). In both sites land-surface fluxes and CO2 fluxes are estimated by the eddy correlation technique while soil moisture was continuously estimated with water content reflectometers, and periodically leaf area index (LAI) was estimated. The following objectives are addressed:1) pointing out the dynamics of land surface fluxes, soil moisture, CO2 and vegetation cover for two contrasting water-limited ecosystems; 2) assess the impact of the soil depth and type on the CO2 and water balance dynamics; 3) evaluate the impact of past and future climate change scenarios on the two contrasting ecosystems. For reaching the objectives an ecohydrologic model that couples a vegetation dynamic model (VDM), and a 3-component (bare soil, grass and woody vegetation) land surface model (LSM) has been used. Historical meteorological data are available from 1922 and hydro-meteorological scenarios are then generated using a weather generator. The VDM-LSM model predict soil water balance and vegetation dynamics for the generated

  2. Importance of spatial factors and temporal scales in environmental risk assessment in marine ecosystems

    International Nuclear Information System (INIS)

    Grebenkov, A.; Linkov, I.; Andrizhievski, A.; Lukashevich, A.; Trifonov, A.

    2004-01-01

    Coastal areas adjacent to the Black Sea, particularly in Crimea, have suffered from inappropriate human activities, poorly regulated industry and former naval bases. Industrial and municipal wastewater pollutants draining into the three major European rivers (the Danube, Dniestr, and Dnieper) and dumping in the open sea result in an enormous increase in contamination level of ecosystems of the Black Sea. In spite of this, Crimea and its adjacent waters is still a globally important center of biological diversity, with an enormous and exciting range of habitats within a comparatively small area. The problem now is to evaluate economically feasible remediation and ecologically sustainable cleanup/reuse alternatives for the most contaminated sites of this area. One of the principal methodological components of such evaluation is a risk-based decision protocol that provides support in analysis of ecological value and reuse options for a chosen site. This paper presents the results of development of a spatially explicit risk assessment technique to be implemented as a part of the decision-making process and gives an example of its application to contaminated marine ecosystems. The model is suggested that takes into account several principal assumptions: (i) spatial heterogeneity of contamination of forage is known and mapped within known location of receptor's habitat, and (ii) the receptor movement and timescale are determined by location, volume and attractiveness of local habitat and forage resources. This implies two models: Spatially Explicit Exposure Assessment Model that calculates internal exposure resulting from ingestion of contaminated feeds, and Probabilistic Receptor Migration Model that generates motivation of behaviour of a receptor while feeding. In the first model, time-dependent accumulation of contamination in receptor tissue is defined by the differential balance equation that takes into account forage consumption rate and excretion rate. In the

  3. How to identify the speed limiting factor of a TCP flow

    NARCIS (Netherlands)

    Timmer, Mark

    2005-01-01

    This thesis develops a method for identifying the speed limiting factor of a TCP flow. Five factors are considered: the receive window, the send buffer, the network and two kinds of application layer factors. Criteria for recognizing each factor based on TCP header information are put forward. These

  4. Integrating Measurements and Models of Water Limitation on Soil and Ecosystem Respiration in Two New England Forests from Hourly to Decadal Timescales.

    Science.gov (United States)

    Sihi, D.; Chen, M.; Davidson, E. A.; Savage, K. E.; Richardson, A. D.; Keenan, T. F.; Hollinger, D. Y.

    2016-12-01

    Soil respiration (SR), the sum of autotrophic (root, Ra) and heterotrophic (microbial, Rh) respiration, is an important component of the global carbon (C) budget and climate change feedbacks from terrestrial ecosystems. Interannual variation of precipitation (and soil moisture) mostly accounts for interannual anomalies in SR. Microbial water stress and limitation of substrate diffusion in dry soil and release from those limitations after a wet-up event also affect SR on short timescales. Variation of precipitation also drives seasonal and interannual patterns of net ecosystem exchange, belowground C allocation, and Ra. Therefore, integration of belowground and aboveground processes is imperative for better understanding of the biosphere-atmosphere C exchange. To that end, we have merged two relatively parsimonious models, a soil enzymatic kinetics model, DAMM (Dual Arrhenius and Michaelis-Menten) and an ecosystem flux model, FöBAAR (Forest Biomass, Assimilation, Allocation and Respiration). We used high-frequency, long-term soil flux data from automated soil chambers and landscape-scale fluxes from eddy covariance towers from the Harvard forest, MA and the Howland forest, ME to develop and validate the merged model and to quantify the uncertainties in a multiple constraints approach. Measurements from trenched and untrenched plots partitioned CO2 flux into Ra and Rh. Preliminary simulations indicated that performance of coupled DAMM- FöBAAR model was improved than FöBAAR-only, as indicated by lower cost functions (model-data mismatch) at the Harvard forest, but not in boreal transition Howland forest, where frequency of droughts is lower due to a shallower water table. Water limitation occurred at Howland, but only briefly and not in most years. Thus, greater confidence in model prediction resulting from inclusion of moisture limitation on substrate availability, an emergent property of DAMM, depends on site conditions, climate, and the temporal scale of

  5. The Climate change impact on the water balance and use efficiency of two contrasting water limited Mediterranean ecosystems in Sardinia

    Science.gov (United States)

    Montaldo, Nicola; Corona, Roberto; Albertson, John

    2016-04-01

    Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFT) competing for the water use. Often deforestation activities have been more intensive along the plan and alluvial river valleys, where deep soils are well suited for agricultural and grass became the primary PFT, while more natural woody vegetation (trees and shrubs) survived in the steep hillslopes and mountain areas, where soil thickness is low, i.e. less attractive for agricultural. Hence, Mediterranean regions are characterized by two main ecosystems, grassland and woodland, which for both natural and anthropogenic causes can grow in soils with also different characteristics (texture, hydraulic properties, depth), highly impacting water resources. Mediterranean regions suffer water scarcity produced in part by natural (e.g., climate variations) influences. For instance, in the Flumendosa basin water reservoir system, which plays a primary role in the water supply for much of southern Sardinia, the average annual input from stream discharge in the latter part of the 20th century was less than half the historic average rate. The precipitation over the Flumendosa basin has decreased, but not at such a drastic rate as the discharge, suggesting a marked non-linear response of discharge to precipitation changes. Indeed, precipitation decreased in winter months, which are crucial for reservoirs recharge through runoff. At the same time air temperature increased during the spring-summer season, when the precipitation slightly increased. The IPCC models predicts a further increase of drought in the Mediterranean region during winter, increasing the uncertainty on the future of the water resources system of these regions. Hence, there is the need to investigate the role of the PFT vegetation dynamics on the soil water budget of these ecosystems in the context of the climate change, and predict hydrologic variables for climate change scenarios

  6. Artificial neural network analysis of factors controlling ecosystem metabolism in coastal systems

    NARCIS (Netherlands)

    Rochelle-Newall, E.J.; Winter, C.; Barrón, C.; Borges, A.V.; Duarte, C.M.; Elliott, M.; Frankignoulle, M.; Gazeau, F.P.H.; Middelburg, J.J.; Pizay, M-D.; Thioulouse, J.; Gattuso, J.P.

    2007-01-01

    Knowing the metabolic balance of an ecosystem is of utmost importance in determining whether the system is a net source or net sink of carbon dioxide to the atmosphere. However, obtaining these estimates often demands significant amounts of time and manpower. Here we present a simplified way to

  7. Critical levels and loads of atmospheric pollutants for terrestrial and aquatic ecosystems. The emergence of a scientific concept. Application potentials and their limits

    International Nuclear Information System (INIS)

    Landmann, G.

    1993-01-01

    The 'critical loads and levels' are defined as the highest atmospheric deposition rate or concentration of a gaseous pollutant, respectively, that will not cause harmful effects on sensitive elements of an ecosystem. The recent emergence of the concept of critical loads and levels is described, from the first explicit mention in 1986 to the production of the first European maps in 1991. The difficulties linked to the definition of the concept and to its english-derived terminology are discussed. The main approaches used for assessing critical loads and levels are briefly described. Important research is developed under the auspices of the Convention of Geneva (Long Range Transboundary Air Pollution Transport, UN-ECE), arising from intensive studies which have been carried out on the effects of air pollution on terrestrial and aquatic ecosystems for the past ten or fifteen years. Current knowledge is summarized, as well as the remaining gaps (and questions) which hinder the calculation of the critical thresholds. Finally, beyond the fundamental relevance of this scientifically sound and easily understood concept, its limits are pointed out. In brief, the 'critical loads and levels' concept is attractive and motivating to many scientists: it implies to apply an integrated and finalized approach, favors the prospecting of poorly known ecosystems and regions, and represents an interesting interface with decision makers

  8. Birds of prey as limiting factors of gamebird populations in Europe: a review.

    Science.gov (United States)

    Valkama, Jari; Korpimäki, Erkki; Arroyo, Beatriz; Beja, Pedro; Bretagnolle, Vincent; Bro, Elisabeth; Kenward, Robert; Mañosa, Santi; Redpath, Stephen M; Thirgood, Simon; Viñuela, Javier

    2005-05-01

    Whether predators can limit their prey has been a topic of scientific debate for decades. Traditionally it was believed that predators take only wounded, sick, old or otherwise low-quality individuals, and thus have little impact on prey populations. However, there is increasing evidence that, at least under certain circumstances, vertebrate predators may indeed limit prey numbers. This potential role of predators as limiting factors of prey populations has created conflicts between predators and human hunters, because the hunters may see predators as competitors for the same resources. A particularly acute conflict has emerged over the past few decades between gamebird hunters and birds of prey in Europe. As a part of a European-wide research project, we reviewed literature on the relationships between birds of prey and gamebirds. We start by analysing available data on the diets of 52 European raptor and owl species. There are some 32 species, mostly specialist predators feeding on small mammals, small passerine birds or insects, which never or very rarely include game animals (e.g. hares, rabbits, gamebirds) in their diet. A second group (20 species) consists of medium-sized and large raptors which prey on game, but for which the proportion in the diet varies temporally and spatially. Only three raptor species can have rather large proportions of gamebirds in their diet, and another seven species may utilise gamebirds locally to a great extent. We point out that the percentage of a given prey species in the diet of an avian predator does not necessarily reflect the impact of that predator on densities of prey populations. Next, we summarise available data on the numerical responses of avian predators to changing gamebird numbers. In half of these studies, no numerical response was found, while in the remainder a response was detected such that either raptor density or breeding success increased with density of gamebirds. Data on the functional responses of

  9. Bottom-up resource limitation: the ecosystem energy balance predicts the quality of nutrition in a herbivore prey population

    DEFF Research Database (Denmark)

    Fernandez, Nestor; Garcia, Monica; Gil, Esperanza

    2014-01-01

    of the herbivore diet has been insufficiently tested. We hypothesized that in drylands, where water availability is a prime control of ecosystem functioning, remote sensing indicators of vegetation drought stress are critical to predict the nutritional quality of herbivore habitats. This hypothesis was analyzed...... by measuring the dynamics in diet quality for the European rabbit, a key prey in Mediterranean communities. Rabbit nutrition was measured in six habitats throughout a year using faecal nitrogen (FN) content, an indicator of the levels of ingested protein. Then we tested the accuracy for predicting diet quality...... contributed to explain the dynamics of diet quality: models including either TVDI or Hr shower a better fit than those exclusively based in EVI (R2 = 0.43—0.60). Whereas FN showed a positive relationship with EVI, the effect of TVDI and Hr was negative. Extracting the temporal component further allowed us...

  10. The Role of Driving Factors in Historical and Projected Carbon Dynamics in Wetland Ecosystems of Alaska

    Science.gov (United States)

    Lyu, Z.; Helene, G.; He, Y.; Zhuang, Q.; McGuire, A. D.; Bennett, A.; Breen, A. L.; Clein, J.; Euskirchen, E. S.; Johnson, K. D.; Kurkowski, T. A.; Pastick, N. J.; Rupp, S. T.; Wylie, B. K.; Zhu, Z.

    2017-12-01

    Wetlands are important terrestrial ecosystems in Alaska. It is important to understand and assess their role in the regional carbon dynamics in response to historical and projected environmental conditions. A coupled modeling framework that incorporates a fire disturbance model and two biogeochemical models was used to assess the relative influence of changing climate, atmospheric carbon dioxide (CO2) concentration, and fire regime on the historical and future carbon balance in wetland ecosystems of the four main Landscape Conservation Cooperatives (LCCs) of Alaska. Simulations were conducted for the historical period (1950-2009) and future projection period (2010-2099). These simulations estimate that the total carbon (C) storage in wetland ecosystems of Alaska is 5556 Tg C in 2009, with 89% of the C stored in soils. An estimated 175 Tg C was lost during the historical period, which is attributed to greater C lost from the Northwest Boreal LCC than C gained from the other three LCCs. The simulations for the projection period were conducted for six different scenarios driven by climate forcings from two different climate models for each of three CO2 emission scenarios. The mean total carbon storage increased 3.94 Tg C/yr by 2099, with variability among the simulations ranging from 2.02 Tg C/yr to 4.42 Tg C/yr. Across the four LCCs, the largest relative C storage increase occurred in the Arctic and North Pacific LCCs. These increases were primarily driven by increases in net primary production (NPP) that were greater than increases in heterotrophic respiration and fire emissions. Our analysis further indicates that NPP increase was primarily driven by CO2 fertilization ( 5% per 100 ppmv increase) as well as by increases in air temperature ( 1% per ° increase). Increases air temperature were estimated to be the primary cause for a projected 47.7% mean increase in wetlands biogenic CH4 emissions among the simulations ( 15% per ° increase). The combined effects of

  11. The Effects of Degradational Factors on the Ecosystem of Mount Madra

    Science.gov (United States)

    Efe, R.; Soykan, A.; Sönmez, S.; Cürebal, I.

    2009-04-01

    Significant degradation has been observed in Turkey's Mediterranean woodlands and mountainous areas. Mediterranean climate prevails in the southern and western part of Turkey. Mount Madra, which is located on Turkey's western Aegean coast, is part of a rangeland which is particularly exposed to the effects of degradation resulting from human activities. The principal factors in the degradation are inappropriate land use, destruction of forests, mining, construction, overgrazing and transhumance. Mount Madra and its environs benefit from a Mediterranean climate, experiencing dry, hot summers and cool, wet winters. The average yearly rainfall is 700-1000 mm, of which most occurs in the winter months. The mountain extends from east to west, and between the South and North slopes there is great variety in terms of plant species and biodiversity. The regeneration of the lost plant cover has been hindered by the mountain's geomorphologic characteristics. The slopes have suffered destruction of vegetation and, as a result of severe erosion, the soil has been swept away and in many places the bedrock has become exposed. The Kozak plateau on mount Madra is notable for the richness of its natural vegetation. This plateau, covered in pine forest (Pinus pinea), is the site for the traditional transhumance of over 500 families. Pine nuts and livestock breeding are livelihood of these families. Mount Madra and its surrounding area is one of the most important locations with gold mining potential in Turkey and it is estimated that it has 16.7 tons of gold reserve. The gold mining which took place on the west of the Madra Mountain around Ovacik village in 1994 led to serious land degradation in the surrounding area. The new mining on the study area and the proposed feldspar mining on the Madra riverbed poses a serious threat to the region's ecosystem and biodiversity. The removal of increasing amounts of granite and other quarrying has had a negative impact on the natural

  12. Millennium Ecosystem Assessment: MA Scenarios

    Data.gov (United States)

    National Aeronautics and Space Administration — The Millennium Ecosystem Assessment: MA Scenarios provide useful insight into the complex factors that drive ecosystem change, estimating the magnitude of regional...

  13. Driving automation forward : human factors for limited-ability autonomous driving systems.

    Science.gov (United States)

    2010-01-01

    Over the past 100 years, there has been a : steady progression of innovations that : enhance the driving experience, in particular : the continuing trend toward automating more : driving tasks. Human Factors for Limited-Ability : Autonomous Drivin...

  14. Photodegradation processes in arid ecosystems: controlling factors and potential application in land restoration

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Luna-Ramos, Lourdes; Oyonarte, Cecilio; Sole Benet, Albert

    2017-04-01

    Water availability plays a fundamental part in controlling biotic processes in arid ecosystems. However, recent evidence suggests that other decisive drivers take part in these processes. Despite low annual rainfall and microbial activity, unexplained high rates of litter decomposition, net nitrogen mineralization, soil enzymatic activity and carbon turnover have been observed in arid ecosystems. These observations have been partly explained by photodegradation, a process that consists of the breakdown of organic matter via solar radiation (UV) and that can increase decomposition rates and lead to changes in the balance of carbon and nutrients between plants, soil and atmosphere. A complete understanding of these mechanisms and its drivers in arid ecosystems remains a critical challenge for the scientific community at the global level. In this research, we conducted a multi-site field experiment to test the effects of photodegradation on decomposition of organic amendments used in ecosystem restoration. The study was carried out during 12 months in two study areas: the Pilbara region in Western Australia (Southern Hemisphere) and the Cabo de Gata Nijar Natural Park, South Spain (Northern Hemisphere). In both sites, four treatments were applied in replicated plots (1x1 m, n=4) that included a control (C) with no soil amendment; organic amendment covering the soil surface (AS); organic amendment incorporated into the soil (AI); and a combination of both techniques, both covering the surface and incorporated into the soil (AS-AI). Different organic amendments (native mulch versus compost) and soil substrates were used at each site according to local practices, but in both sites these were applied to increase soil organic matter up to 2%. At the two locations, a radiometer and a logger with a soil temperature and soil moisture probe were installed to monitor UV radiation and soil conditions for the duration of the trial. Soil microbial activity, soil CO2 efflux, and

  15. Coastal ecosystems, productivity and ecosystem protection: Coastal ecosystem management

    Energy Technology Data Exchange (ETDEWEB)

    Ngoile, M.A.K.; Horrill, C.J. (Inst. of Marine Sciences, Zanzibar (Tanzania, United Republic of))

    1993-01-01

    The coastal zone is a complex ecosystem under the influence of physical, chemical and biological processes. Under natural conditions these processes interact and maintain an equilibrium in the coastal ecosystem. Man makes a variety of important uses of coastal resources, ranging from harvesting of living resources, extraction of nonliving resources, and recreation, to the disposal of wastes. Man's extensive use of the oceans introduces factors which bring about an imbalance in the natural processes, and may result in harmful and hazardous effects to life hindering further use. Man's pressure on the resources of the coastal zone is already manifest and will increase manifold. This calls for an immediate solution to the protection and sustainable use of coastal resources. The current sectorized approach to the management of human activities will not solve the problem because the different resources of the coastal zone interact in such a manner that disturbances in one cause imbalance in the others. This is further complicated by the sectorized approach to research and limited communication between policy makers, managers, and scientists. This paper discusses strategies for managing coastal-resources use through an integrated approach. The coastal zone is presented as a unified ecosystem in equilibrium and shows that man's extensive use of the coastal resources destabilizes this equilibrium. Examples from the East Africa Region are presented. 15 refs, 2 figs, 3 tabs

  16. Coastal ecosystems, productivity and ecosystem protection: Coastal ecosystem management

    International Nuclear Information System (INIS)

    Ngoile, M.A.K.; Horrill, C.J.

    1993-01-01

    The coastal zone is a complex ecosystem under the influence of physical, chemical and biological processes. Under natural conditions these processes interact and maintain an equilibrium in the coastal ecosystem. Man makes a variety of important uses of coastal resources, ranging from harvesting of living resources, extraction of nonliving resources, and recreation, to the disposal of wastes. Man's extensive use of the oceans introduces factors which bring about an imbalance in the natural processes, and may result in harmful and hazardous effects to life hindering further use. Man's pressure on the resources of the coastal zone is already manifest and will increase manifold. This calls for an immediate solution to the protection and sustainable use of coastal resources. The current sectorized approach to the management of human activities will not solve the problem because the different resources of the coastal zone interact in such a manner that disturbances in one cause imbalance in the others. This is further complicated by the sectorized approach to research and limited communication between policy makers, managers, and scientists. This paper discusses strategies for managing coastal-resources use through an integrated approach. The coastal zone is presented as a unified ecosystem in equilibrium and shows that man's extensive use of the coastal resources destabilizes this equilibrium. Examples from the East Africa Region are presented. 15 refs, 2 figs, 3 tabs

  17. France's Financial (Eco)system. Improving the integration of sustainability factors

    International Nuclear Information System (INIS)

    Morel, Romain; Cochran, Ian; Robins, Nick

    2015-11-01

    In the run-up of the COP21, much international attention is focused on France. While mainly related to climate change negotiations, this creates an opportunity to take a broader look at French domestic policies and practices on sustainability. This report presents the French financial system and draws lessons from the French ongoing experience in improving the integration of sustainability issues that could be shared with other countries. The present report summarizes and analyses the key initiatives and dynamics at stake in France. It focuses on both the climate-related issues that have recently received significant attention and the development of broader Environmental, Social and Governance (ESG) issues over the past twenty years. The dynamics that have shaped the last two decades have both led to and been influenced by the emergence of an 'ecosystem' of commercial, public and non-profit actors and experts involved in the appropriation and integration of sustainability issues across the sector. Using the framework of analysis presented in the UNEP Inquiry global report, this case study examines the landscape of actors, private initiatives and public policy that has driven the emergence of this ecosystem and helped foster capacity building and the acquisition of expertise among sectoral actors. (authors)

  18. Impact of selected risk factors on expected lifetime without long-standing, limiting illness in Denmark

    DEFF Research Database (Denmark)

    Brønnum-Hansen, Henrik; Juel, Knud; Davidsen, Michael

    2007-01-01

    OBJECTIVE: To estimate the impacts of tobacco smoking, high alcohol consumption, physical inactivity and overweight on expected lifetime with and without long-standing, limiting illness. METHODS: Life tables for each level of exposure to the risk factors were constructed, mainly on the basis...... health due to interventions against these risk factors could be evaluated, when the prevalence of exposure to the risk factor is available....

  19. Metal toxicity characterization factors for marine ecosystems: considering the importance of the estuary for freshwater emissions

    DEFF Research Database (Denmark)

    Dong, Yan; Rosenbaum, Ralph K.; Hauschild, Michael Zwicky

    2017-01-01

    for metal emissions to freshwater and coastal seawater, respectively. The new CFs were applied to calculate endpoint impact scores for the same amount of metal emission to each compartment, to compare the relative ecotoxicity damages in freshwater and marine ecosystems in LCA. Site-dependent marine CFs...... as the best one. Endpoint marine and freshwater metals CFs were developed to calculate endpoint ecotoxicity impact scores. Marine ecotoxicity CFs are 1.5 orders of magnitude lower for emission to freshwater than for emission to seawater for Cr, Cu, and Pb, due to notable removal fractions both in freshwater...... CFs for emission to seawater are 1–4 orders of magnitude lower except for Pb. The new site-generic marine CFs for emission to freshwater lie within two orders of magnitude difference from USES-LCA 2.0 CFs. The comparative contribution share analysis shows a poor agreement of metal toxicity ranking...

  20. Impact of gamma radiation on nonliving factors in an aquatic ecosystem

    International Nuclear Information System (INIS)

    Ishii, Nobuyoshi

    2011-01-01

    DNA is an abiotic substance, and it is an essential substance as a genetic material for all organisms. However, DNA is not always present within cell. In aquatic environments, a form of naked extracellular DNA is omnipresent at concentrations from 0.2 to 88 g per liter. Extracellular DNA can serve as a source of carbon and energy supporting microbial growth and is required for bacterial biofilm formation. In addition, extracellular DNA has a sufficient molecular weight to retain its genetic function. In fact, gene sequences had been detected in the extracellular DNA fraction. Therefore, extracellular DNA is an important component of aquatic ecosystems. In this paper, the impact of gamma radiation on the extracellular DNA was described. (author)

  1. Persistent organic pollutants (POPs) as environmental risk factors in remote high-altitude ecosystems.

    Science.gov (United States)

    Kallenborn, Roland

    2006-01-01

    Persistent organic pollutants (POPs), and their transformation products, are the most investigated organic environmental contaminants within the past five decades. Organochlorines have been found in virtually all environmental compartments on the globe. Severe environmental implications have been shown to be associated with the presence of the POP group of contaminants in the environment. However, in the late 1990s, Canadian scientists first pinpointed the implication of POPs for high-altitude environments in a comprehensive way (Blais et al., 1998, Nature 395, 585-588). Under certain meteorological and geographic conditions, high-altitude environments can serve as "cold condensers" for atmospheric POP loadings. Subsequent investigations in high-altitude environments in Asia, Europe, and North and South America have confirmed suspicions that high-altitude mountainous regions have the potential to serve as focus regions for POPs and even for nonpersistent, medium-lived contaminants, such as "currently used pesticides", due to cold condensation and deposition in high altitudes. Although the presence and the altitude-dependent increase of POP levels in mountainous regions are confirmed by many international studies, the ecotoxicological consequences still remain largely unknown. At present, only a few studies have been published describing the biological effects in high-altitude environments due to increased POP exposure. Therefore, in this early stage of the international research effort on the ecotoxicological risk evaluation of persistent contaminants in high-altitude, pristine ecosystems, the present review intends to summarize the current state of research on POPs in high-altitude environments and draw preliminary conclusions on possible consequences of the presence of POPs in mountainous ecosystems based on currently available information from alpine and related Arctic environments.

  2. Performance evaluation of five Mediterranean species to optimize ecosystem services of green roofs under water-limited conditions.

    Science.gov (United States)

    Azeñas, V; Janner, I; Medrano, H; Gulías, J

    2018-04-15

    Rapid urban growth in Mediterranean cities has become a serious environmental concern. Due to this expansion, which covers adjacent horizontal ground, a critical deficit of green areas has been increasing. Moreover, irrigation is considered an important issue since water is one of the most limiting natural resources all over the world. The main objective of this study was to perform a long-term experiment to assess five Mediterranean species for extensive green roof implementation in Mediterranean-climate conditions. Brachypodium phoenicoides, Crithmum maritimum, Limonium virgatum, Sedum sediforme and Sporobolus pungens were grown in experimental modules under well-watered and water-limited conditions (irrigation at 50% and 25% ET 0 , respectively). Plant growth and cover, relative appearance, color evolution and water use were determined periodically for two years. Shoot and root biomass were quantified at the end of the experimental period. The effects of the irrigation treatments and seasonal changes were assessed to identify the advantages and disadvantages of each species according to their environmental performance. All species survived and showed adequate esthetic performance and plant cover during the experiment. S. sediforme registered the lowest variation of relative appearance along the experiment, the highest biomass production and the lowest water consumption. Nevertheless, B. phoenicoides appeared to be an interesting alternative to S. sediforme, showing high esthetic performance and water consumption throughout the rainy season, suggesting a potential role of this species in stormwater regulation related with runoff reduction. S. pungens performed well in summer but presented poor esthetics during winter. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Millennium Ecosystem Assessment: MA Ecosystems

    Data.gov (United States)

    National Aeronautics and Space Administration — The Millennium Ecosystem Assessment: MA Ecosystems provides data and information on the extent and classification of ecosystems circa 2000, including coastal,...

  4. Mathematical modeling of plant allelopathic hormesis based on ecological-limiting-factor models.

    Science.gov (United States)

    Liu, Yinghu; Chen, Xiaoqiu; Duan, Shunshan; Feng, Yuanjiao; An, Min

    2010-05-28

    Allelopathy arises from the release of chemicals by one plant species that affect other species in its vicinity, usually to their detriment. Allelopathic effects have been demonstrated to be limiting factors for species distributions and ecological processes in some natural or agricultural communities. Based on the biphasic hormetic responses of plants to allelochemicals, ecological-limiting-factor models were introduced into the An-Johnson-Lovett hormesis model to improve modelling the phenomenon of allelopathic hormesis and to better reflect the nature of allelopathy as a limiting factor in ecological processes. Outcomes of the models have been compared for several sets of experimental data from the literature and good agreement between the models and data was observed, which indicates that the new models give some insight into the ecological mechanisms involved and may provide more options for modelling the allelopathic phenomenon as well as platforms for further research on plant allelopathic hormesis.

  5. Mercury in soils, lakes, and fish in Voyageurs National Park (Minnesota): Importance of atmospheric deposition and ecosystem factors

    Science.gov (United States)

    Wiener, J.G.; Knights, B.C.; Sandheinrich, M.B.; Jeremiason, Jeffrey D.; Brigham, M.E.; Engstrom, D.R.; Woodruff, L.G.; Cannon, W.F.; Balogh, S.J.

    2006-01-01

    Concentrations of methylmercury in game fish from many interior lakes in Voyageurs National Park (MN, U.S.A.) substantially exceed criteria for the protection of human health. We assessed the importance of atmospheric and geologic sources of mercury to interior lakes and watersheds within the Park and identified ecosystem factors associated with variation in methylmercury contamination of lacustrine food webs. Geologic sources of mercury were small, based on analyses of underlying bedrock and C-horizon soils, and nearly all mercury in the O- and A-horizon soils was derived from atmospheric deposition. Analyses of dated sediment cores from five lakes showed that most (63% ?? 13%) of the mercury accumulated in lake sediments during the 1900s was from anthropogenic sources. Contamination of food webs was assessed by analysis of whole, 1-year-old yellow perch (Perca flavescens), a regionally important prey fish. The concentrations of total mercury in yellow perch and of methylmercury in lake water varied substantially among lakes, reflecting the influence of ecosystem processes and variables that affect the microbial production and abundance of methylmercury. Models developed with the information-theoretic approach (Akaike Information Criteria) identified lake water pH, dissolved sulfate, and total organic carbon (an indicator of wetland influence) as factors influencing methylmercury concentrations in lake water and fish. We conclude that nearly all of the mercury in fish in this seemingly pristine landscape was derived from atmospheric deposition, that most of this bioaccumulated mercury was from anthropogenic sources, and that both watershed and lacustrine factors exert important controls on the bioaccumulation of methylmercury. ?? 2006 American Chemical Society.

  6. JOB BEHAVIORAL FACTORS AND TURNOVER INTENTION: EVIDENCE FROM SIME DARBY PROPERTY LIMITED

    OpenAIRE

    Amran Awang; Abdul Razak Amir; Wirda Osman

    2013-01-01

    Some job behavioral factors are utilized to examine their relationship with turnover intention among 201 employees in Sime Darby Property (Malaysia) Limited. Job satisfaction, job stress, organizational commitment, job enrichment and person-organization fit are the job behavioral factors selected for the study. The variables used in the study justify the reliability scores consistent with indicators in previous studies. Research methodology justifies the quantitative requirements ...

  7. Functional limitation and associated factors in outpatients with ankylosing spondylitis in Southwest China.

    Science.gov (United States)

    Song, Yuqing; Wang, Chen; Chen, Hong

    2017-04-01

    Functional limitation is often complained by patients with ankylosing spondylitis (AS). With a rising number of patients suffering from AS, there are a limited number of reports focusing on functional limitation of AS in Chinese patients. This study was conducted to investigate the level of functional limitation and explore its associations with demographic, disease-related factors. A total of 303 AS outpatients were recruited in this cross-sectional study from a tertiary general hospital in Southwest China. Functional limitation was measured by the Bath Ankylosing Spondylitis Functional Index (BASFI). Other data were collected by the following questionnaires: the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Bath Ankylosing Spondylitis Patient Global Score (BAS-G), and the Pittsburgh Sleep Quality Index Questionnaire (PSQI). Finally, 295 outpatients with AS completed this survey. The median BASFI was 0.80. Worse function limitation was found in outpatients with extra-spinal manifestation, older age, lower household income, more back pain, higher disease activity and morning stiffness, poorer sleep, and worse patient's well-being (all P < 0.05). Multivariate regression analysis indicated that patient's well-being (P < 0.001), disease activity (P < 0.001), and disease duration (P < 0.05) were the positive predictors of functional limitation. AS outpatients in Southwest China had a mild level of functional limitation. The factors associated with functional limitation included disease duration, disease activity, and patients' well-being, which should be taken into consideration when assessing functional limitation of AS outpatients. Besides, more comprehensive and targeted interventions should be conducted for AS patients as early as possible, which will be effective to improve functional outcome.

  8. Spatiotemporal Variation of Karst Ecosystem Service Values and Its Correlation with Environmental Factors in Northwest Guangxi, China

    Science.gov (United States)

    Zhang, Mingyang; Zhang, Chunhua; Wang, Kelin; Yue, Yuemin; Qi, Xiangkun; Fan, Feide

    2011-11-01

    In this investigation we analyzed the spatiotemporal variation of ecosystem service values (ESVs) and its correlation with numerous environmental factors (EFs) for the karst region of Northwest Guangxi, China, from 1985 to 2005 using remote sensing, geographic information systems (GIS) and statistical techniques. The results indicate that historically ESVs for this karst region decreased from 1985 (109.652 billion Yuan) to 1990 (88.789 billion Yuan) and then increased at the turn of the twenty-first century. However, the ESVs in both 2000 (103.384 billion Yuan) and 2005 (106.257 billion Yuan) never achieved the level recorded in 1985. The total of nutrient cycling, organic production and gas regulation combined were 72.69, 64.57, 70.18 and 72.10% of ESVs in 1985, 1990, 2000 and 2005, respectively. In contrast, the ESVs of water conservation, soil reservation, recreation and culture were determined to be relatively low contributing only 17.44, 23.82, 19.26 and 24.76% of total ESVs, respectively, during these four years. With regards to the spatial distribution of ESVs, larger values were recorded in the west and smaller ones recorded in the east. The most significant factors that were deemed to influence ESVs are annual rainfall, per capita cropland, slope and vegetation coverage. Annual rainfall and slope exert a negative force, whereas per capita cropland and vegetation coverage exert a positive force on ESVs. The results of the study would suggest that ecosystem conditions of this important karst region have been improved as the result of the implementation of rocky desertification control policies.

  9. Radiological bioconcentration factors for aquatic, terrestrial, and wetland ecosystems at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Cummins, C.L.

    1994-09-01

    As a result of operations at the Savannah River Site (SRS), over 50 radionuclides have been released to the atmosphere and to onsite streams and seepage basins. Now, many of these radionuclides are available to aquatic and/or terrestrial organisms for uptake and cycling through the food chain. Knowledge about the uptake and cycling of these radionuclides is now crucial in evaluating waste management and clean-up alternatives for the site. Numerous studies have been conducted at the SRS over the past forty years to study the uptake and distribution of radionuclides in the Savannah River Site environment. In many instances, bioconcentration factors have been calculated to quantify the uptake of a radionuclide by an organism from the surrounding medium (i.e., soil or water). In the past, it has been common practice to use bioconcentration factors from the literature because site-specific data were not readily available. However, because of the variability of bioconcentration factors due to experimental or environmental conditions, site-specific data should be used when available. This report compiles and summarizes site-specific bioconcentration factors for selected radionuclides released at the Savannah River Site (SRS). An extensive literature search yielded site-specific bioconcentration factors for cesium, strontium, cobalt, plutonium, americium, curium, and tritium. These eight radionuclides have been the primary radionuclides studied at SRS because of their long half lives or because they are major contributors to radiological dose from exposure. For most radionuclides, it was determined that the site-specific bioconcentration factors were higher than those reported in literature. This report also summarizes some conditions that affect radionuclide bioavailability to and bioconcentration by aquatic and terrestrial organisms.

  10. Radiological bioconcentration factors for aquatic, terrestrial, and wetland ecosystems at the Savannah River Site

    International Nuclear Information System (INIS)

    Cummins, C.L.

    1994-09-01

    As a result of operations at the Savannah River Site (SRS), over 50 radionuclides have been released to the atmosphere and to onsite streams and seepage basins. Now, many of these radionuclides are available to aquatic and/or terrestrial organisms for uptake and cycling through the food chain. Knowledge about the uptake and cycling of these radionuclides is now crucial in evaluating waste management and clean-up alternatives for the site. Numerous studies have been conducted at the SRS over the past forty years to study the uptake and distribution of radionuclides in the Savannah River Site environment. In many instances, bioconcentration factors have been calculated to quantify the uptake of a radionuclide by an organism from the surrounding medium (i.e., soil or water). In the past, it has been common practice to use bioconcentration factors from the literature because site-specific data were not readily available. However, because of the variability of bioconcentration factors due to experimental or environmental conditions, site-specific data should be used when available. This report compiles and summarizes site-specific bioconcentration factors for selected radionuclides released at the Savannah River Site (SRS). An extensive literature search yielded site-specific bioconcentration factors for cesium, strontium, cobalt, plutonium, americium, curium, and tritium. These eight radionuclides have been the primary radionuclides studied at SRS because of their long half lives or because they are major contributors to radiological dose from exposure. For most radionuclides, it was determined that the site-specific bioconcentration factors were higher than those reported in literature. This report also summarizes some conditions that affect radionuclide bioavailability to and bioconcentration by aquatic and terrestrial organisms

  11. Ecosystem service trade-offs and their influencing factors: A case study in the Loess Plateau of China.

    Science.gov (United States)

    Feng, Qiang; Zhao, Wenwu; Fu, Bojie; Ding, Jingyi; Wang, Shuai

    2017-12-31

    Soil erosion control (SEC), carbon sequestration (CAS), and soil moisture (SMO) strongly interact in the semi-arid Loess Plateau. Since SMO has supportive effects on SEC and CAS, it can be considered as ecosystem service (ES), and there is an immediate need to coordinate the relationships among these ecosystem services (ESs) to promote the sustainability of vegetation recovery. In this study, we quantified the ESs, ES trade-offs, and the environmental factors in 151 sample plots in the Ansai watershed, and we used a redundancy analysis (RDA) to clarify the effects of environmental factors on these ESs and their trade-offs. The results were as follows: (1) the general trend in the SEC of vegetation types was Robinia pseudoacacia (CH)>native grass (NG)>small arbor (ST)>Hippophae rhamnoides (SJ)>artificial grass (AG)>Caragana korshinskii (NT)>apple orchard (GY)>crop (CP); the CAS trend was CH>SJ>NT>AG>CP>ST>GY>NG; and the SMO trend was CP>NG>GY>AG>SJ>ST>CH>NT. (2) For SEC-SMO trade-offs, the influence of vegetation type, altitude, silt and sand composition was dominant. The arrangement of NG, AG, and SJ could decrease the extent of the trade-offs. (3) For CAS-SMO trade-offs, vegetation coverage and types were the dominant factors, but the effects were not complex. The extent of these trade-offs was lowest for NT, and that for SJ was the second lowest. (4) Considering the relationships among the three ESs, SJ was the most appropriate afforestation plant. Combing the vegetation types, slope position, slope gradient, and soil properties could regulate these ES relationships. The dominant factors influencing ES trade-offs varied among the different soil layers, so we must consider the corresponding influencing factors to regulate ESs. Moreover, manual management measures were also important for coordinating the ES relationships. Our research provides a better understanding of the mechanisms influencing the relationships among ESs. Copyright © 2017 Elsevier B.V. All

  12. Interplay between abiotic factors and species assemblages mediated by the ecosystem engineer Sabellaria alveolata (Annelida: Polychaeta)

    Science.gov (United States)

    Jones, Auriane G.; Dubois, Stanislas F.; Desroy, Nicolas; Fournier, Jérôme

    2018-01-01

    , associated and control sediment assemblages. These two parameters are under the ecosystem engineer's influence stressing its importance in structuring benthic macrofauna. Furthermore, in late summer but not in late winter, presence/absence and abundance-based beta diversity were positively correlated to our disturbance proxy (mud content) a tendency driven by a species replacement and a rise in the associated fauna density. Our first set of results highlight the importance of S. alveolata reefs as benthic primary production enhancers via their physical structure and their biological activity. The results obtained using beta diversity indices emphasize the importance of recruitment in structuring the reef's macrofauna and - paradoxically - the ecological value of S. alveolata degraded forms as biodiversity and recruitment promoters.

  13. Lifestyle Factors and Incident Mobility Limitation in Obese and Non-obese Older Adults.

    NARCIS (Netherlands)

    Koster, A.; Penninx, B.W.J.H.; Newman, A.B.; Visser, M.; van Gool, C.H.; Harris, T.B.; van Eijk, J.T.; Kempen, G.I.; Brach, J.S.; Simonsick, E.M.; Houston, D.K.; Tylavsky, F.A.; Rubin, S.M.; Kritchevsky, S.B.

    2007-01-01

    Objective: This study examines the association between incident mobility limitation and 4 lifestyle factors: smoking, alcohol intake, physical activity, and diet in well-functioning obese (n = 667) and non-obese (n = 2027) older adults. Research Methods and Procedures: Data were from men and women,

  14. What is the most prominent factor limiting photosynthesis in different layers of a greenhouse cucumber canopy?

    NARCIS (Netherlands)

    Chen, T.W.; Henke, M.; Visser, de P.H.B.; Buck-Sorlin, G.H.; Wiechers, D.; Kahlen, K.; Stützel, H.

    2014-01-01

    Background and Aims Maximizing photosynthesis at the canopy level is important for enhancing crop yield, and this requires insights into the limiting factors of photosynthesis. Using greenhouse cucumber (Cucumis sativus) as an example, this study provides a novel approach to quantify different

  15. Understanding the factors that limit restoration success on a recreation-impacted subalpine site

    Science.gov (United States)

    Catherine Zabinski; David Cole

    2000-01-01

    Factors that limit successful revegetation of a subalpine site were studied through a combination of soil assays, greenhouse studies, and field manipulations. Campsite soils had higher available nitrogen, lower microbial community diversity, and lower seed bank density than undisturbed soils. In the greenhouse, there was no significant difference in plant growth on...

  16. Factors associated with pain intensity and physical limitations after lateral ankle sprains

    NARCIS (Netherlands)

    Briet, Jan Paul; Houwert, Roderick M.; Hageman, Michiel G J S; Hietbrink, Falco; Ring, David C.; Verleisdonk, Egbert Jan J M

    2016-01-01

    Background Swelling, tenderness, and ecchymosis don't correlate with time to functional recovery in patients with a lateral ankle sprain. It is established that psychosocial factors such as symptoms of depression and low pain self-efficacy correlate with pain intensity and magnitude of limitations

  17. The zero-slope limit of Witten's string field theory with Chan-Paton factors

    International Nuclear Information System (INIS)

    Dearnaley, R.

    1990-01-01

    I demonstrate that open-string field theory with Chan-Paton factors has Yang-Mills theory as its off-shell zero-slope limit. I first add Chan-Paton group factors both to Witten's string field theory and to a non-oriented extension of it. The quadratic and cubic interactions between massless fields are calculated in the zero-slope limit by means of the Neumann functions computed for Witten's theory by Gross and Jevicki and by Cremmer, Schwimmer and Thorn. I show that the only other terms (up to renormalisation) appearing in the zero-slope limit are those from tree-level interactions between four massless fields. These are evaluated off-shell using the conformal mapping and Neumann function techniques developed by Giddings, by Sloan, and by Samuel. The resulting lagrangian is Yang-Mills theory in the Feynman-Lorentz-Baulieu-Thierry-Mieg gauge. (orig.)

  18. Interaction of extrinsic chemical factors affecting photodegradation of dissolved organic matter in aquatic ecosystems

    Czech Academy of Sciences Publication Activity Database

    Porcal, Petr; Dillon, P. J.; Molot, L. A.

    2014-01-01

    Roč. 13, č. 5 (2014), s. 799-812 ISSN 1474-905X R&D Projects: GA ČR(CZ) GAP503/12/0781 Institutional support: RVO:60077344 Keywords : photodegradation * dissolved organic matter * calcium * nitrate * iron * pH Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.267, year: 2014

  19. Research frontiers in climate change: Effects of extreme meteorological events on ecosystems; Limites de la recherche dans le domaine des changements climatiques: effets des evenements meteorologiques extremes sur les ecosystemes

    Energy Technology Data Exchange (ETDEWEB)

    Jentsch, A. [Disturbance Ecology and Vegetation Dynamics, Helmholtz Centre for Environmental Research - UFZ, Leipzig (Germany); Jentsch, A. [Bayreuth Univ. (Germany); Beierkuhnlein, C. [Bayreuth Univ., Biogeography (Germany)

    2008-09-15

    Climate change will increase the recurrence of extreme weather events such as drought and heavy rainfall. Evidence suggests that modifications in extreme weather events pose stronger threats to ecosystem functioning than global trends and shifts in average conditions. As ecosystem functioning is connected with ecological services, this has far-reaching effects on societies in the 21. century. Here, we: (i) present the rationale for the increasing frequency and magnitude of extreme weather events in the near future; (ii) discuss recent findings on meteorological extremes and summarize their effects on ecosystems and (iii) identify gaps in current ecological climate change research. (authors)

  20. Endophytic and Epiphytic Phyllosphere Fungal Communities Are Shaped by Different Environmental Factors in a Mediterranean Ecosystem.

    Science.gov (United States)

    Gomes, Teresa; Pereira, José Alberto; Benhadi, Jacinto; Lino-Neto, Teresa; Baptista, Paula

    2018-03-02

    The diversity and factors influencing fungal assemblages in phyllosphere of Mediterranean tree species have been barely studied, especially when endophytic and epiphytic communities are simultaneously considered. In this work, the endophytic and epiphytic fungal communities from olive tree phyllosphere were studied. This tree species is natural from the Mediterranean region and adapted to grow under adverse climatic conditions. The main objectives were to determine whether there are differences between both fungal communities and to examine whether different abiotic (climate-related) and biotic (plant organs) factors play a pivotal role in structuring these communities. Both communities differed in size and composition, with epiphytic community being richer and more abundant, displaying also a dominance of melanized fungi. Season was the major driver of community composition, especially of epiphytes. Other drivers shaping epiphytes were wind speed and temperature, while plant organ, rainfall, and temperature were the major drivers for endophytic composition. In contrast, canopy orientation caused slight variations in community composition of fungi, but with distinct effects in spring and autumn seasons. In conclusion, epiphytic and endophytic communities are not driven by the same factors. Several sources of variation undergo complex interactions to form and maintain phyllosphere fungal community in Mediterranean climates. Climatic parameters have influence on these fungal communities, suggesting that they are likely to be affected by climate changes in a near future.

  1. Human and environmental factors influencing fire trends in different forest ecosystems

    OpenAIRE

    Román Cuesta, Rosa María

    2002-01-01

    Consultable des del TDX Títol obtingut de la portada digitalitzada La mayoría de los bosques del planeta, exceptuando, quizá, el cinturón más húmedo del trópico, han sufrido perturbaciones recurrentes por incendios, desde hace miles de años. Sin embargo, en el último siglo, la combinación de factores socio-económicos y ambientales han alterado la frecuencia y distribución de incendios en casi todos los ecosistemas forestales. Esta mala distribución del fuego ha conllevado la acumulación...

  2. Radiological bioconcentration factors for aquatic, terrestrial, and wetland ecosystems at the Savannah River site

    International Nuclear Information System (INIS)

    Friday, G.P.; Cummins, C.L.; Schwartzman, A.L.

    1996-01-01

    Since the early 1950s, the Savannah River Site (SRS) released over 50 radionuclides into the environment while producing nuclear defense materials. These releases directly exposed aquatic and terrestrial biota to ionizing radiation from surface water, soil, and sediment, and also indirectly by the ingestion of items in the food chain. As part of new missions to develop waste management strategies and identify cost-effective environmental restoration options, knowledge concerning the uptake and distribution of these radionuclides is essential. This report compiles and summarizes site-specific bioconcentration factors for selected radionuclides released at SRS

  3. Radiological bioconcentration factors for aquatic, terrestrial, and wetland ecosystems at the Savannah River site

    Energy Technology Data Exchange (ETDEWEB)

    Friday, G.P.; Cummins, C.L.; Schwartzman, A.L.

    1996-12-31

    Since the early 1950s, the Savannah River Site (SRS) released over 50 radionuclides into the environment while producing nuclear defense materials. These releases directly exposed aquatic and terrestrial biota to ionizing radiation from surface water, soil, and sediment, and also indirectly by the ingestion of items in the food chain. As part of new missions to develop waste management strategies and identify cost-effective environmental restoration options, knowledge concerning the uptake and distribution of these radionuclides is essential. This report compiles and summarizes site-specific bioconcentration factors for selected radionuclides released at SRS.

  4. Breastfeeding in the first hour of life and modern technology: prevalence and limiting factors

    Directory of Open Access Journals (Sweden)

    Maria Cristina Pillegi

    2008-12-01

    Full Text Available Objective: To identify the prevalence and limiting factors ofbreastfeeding in the first hour of life at the Maternity Center of HospitalIsraelita Albert Einstein, where the predominant model of childbirthcare is largely based on the use of modern technology. Methods: Aretrospective study with quantitative analysis in a middle and upperclass population of different cultural backgrounds. Data were obtainedfrom the delivery record book in a total of 12,350 births from January2004 to December 2007. Results: Of 12,350 births, 3,277 (26.9%were excluded because of contraindications to breastfeeding in thefirst hour of life such as: prematurity, respiratory distress, adverseeffects of anesthesia, obstetric conditions, congenital malformation,and others. Other 180 cases were excluded due to missing data.Of the remaining 8,893 cases, 2,279 (18.7% were not breastfedbecause of limiting factors that require improvement actions: highdelivery turnover, patient refusal, medical refusal, tiredness due toprolonged labor, loss of data recording. Cesarean delivery and the useof anesthesia did neither prevent breastfeeding in the first hour of lifenor skin-to-skin contact. The prevalence was 74.3%. Conclusions:The use of technology and the hospital practices interfere inbreastfeeding, but are not factors that prevent it. The identificationof the prevalence and limiting factors contributes to the evaluationof the care provided and elaboration of nursing interventions forcontinuous improvement of the care practice. Improvement actionsshould include prenatal care and delivery itself.

  5. Seasonal variations in terpene emission factors of dominant species in four ecosystems in NE Spain

    Science.gov (United States)

    Llusia, Joan; Peñuelas, Josep; Guenther, Alex; Rapparini, Francesca

    2013-05-01

    We studied the daily patterns in the rates of foliar terpene emissions by four typical species from the Mediterranean region in two days of early spring and two days of summer in 4 localities of increasing biomass cover in Northern Spain. The species studied were Thymelaea tinctoria (in Monegros), Quercus coccifera (in Garraf), Quercus ilex (in Prades) and Fagus sylvatica (in Montseny). Of the total 43 VOCs detected, 23 were monoterpenes, 5 sesquiterpenes and 15 were not terpenes. Sesquiterpenes were the main terpenes emitted from T. tinctoria. Total VOC emission rates were on average about 15 times higher in summer than in early spring. The maximum rates of emission were recorded around midday. Emissions nearly stopped in the dark. No significant differences were found for nocturnal total terpene emission rates between places and seasons. The seasonal variations in the rate of terpene emissions and in their chemical composition can be explained mainly by dramatic changes in emission factors (emission capacity) associated in some cases, such as for beech trees, with very different foliar ontogenical characteristics between spring and summer. The results show that temperature and light-standardised emission rates were on average about 15 times higher in summer than in early spring, which, corroborating other works, calls to attention when applying the same emission factor in modelling throughout the different seasons of the year.

  6. Power and limitation of soil properties as predictors of rangeland health and ecosystem functioning in a Northern mixed-grass prairie[Abstract

    Science.gov (United States)

    Soil properties are thought to affect rangeland ecosystem functioning (e.g. primary productivity, hydrology), and thus soil variables that are consistently correlated with key ecosystem functions may be general indicators of rangeland health. We summarize results from several studies in mixed-grass...

  7. Ecosystem Services

    Science.gov (United States)

    Ecosystem goods and services are the many life-sustaining benefits we receive from nature and contribute to environmental and human health and well-being. Ecosystem-focused research will develop methods to measure ecosystem goods and services.

  8. Effects of Climatic Factors and Ecosystem Responses on the Inter-Annual Variability of Evapotranspiration in a Coniferous Plantation in Subtropical China

    Science.gov (United States)

    Xu, Mingjie; Wen, Xuefa; Wang, Huimin; Zhang, Wenjiang; Dai, Xiaoqin; Song, Jie; Wang, Yidong; Fu, Xiaoli; Liu, Yunfen; Sun, Xiaomin; Yu, Guirui

    2014-01-01

    Because evapotranspiration (ET) is the second largest component of the water cycle and a critical process in terrestrial ecosystems, understanding the inter-annual variability of ET is important in the context of global climate change. Eight years of continuous eddy covariance measurements (2003–2010) in a subtropical coniferous plantation were used to investigate the impacts of climatic factors and ecosystem responses on the inter-annual variability of ET. The mean and standard deviation of annual ET for 2003–2010 were 786.9 and 103.4 mm (with a coefficient of variation of 13.1%), respectively. The inter-annual variability of ET was largely created in three periods: March, May–June, and October, which are the transition periods between seasons. A set of look-up table approaches were used to separate the sources of inter-annual variability of ET. The annual ETs were calculated by assuming that (a) both the climate and ecosystem responses among years are variable (Vcli-eco), (b) the climate is variable but the ecosystem responses are constant (Vcli), and (c) the climate is constant but ecosystem responses are variable (Veco). The ETs that were calculated under the above assumptions suggested that the inter-annual variability of ET was dominated by ecosystem responses and that there was a negative interaction between the effects of climate and ecosystem responses. These results suggested that for long-term predictions of water and energy balance in global climate change projections, the ecosystem responses must be taken into account to better constrain the uncertainties associated with estimation. PMID:24465610

  9. Coverage of Native Plants Is Key Factor Influencing the Invasibility of Freshwater Ecosystems by Exotic Plants in China

    Directory of Open Access Journals (Sweden)

    Haihao Yu

    2018-02-01

    Full Text Available Understanding the biotic and abiotic factors that influence the susceptibility of a community to invasion is beneficial for the prediction and management of invasive species and the conservation of native biodiversity. However, the relationships between factors and invasibility of a community have not been fully confirmed, and the factors most associated with the susceptibility of a community to invasion have rarely been identified. In this study, we investigated the species richness patterns in aquatic exotic and native plants and the relationships of exotic species richness with habitat and water environment factors in 262 aquatic plant communities in China. A total of 11 exotic plant species were recorded in our field survey, and we found neither a negative nor a positive relationship between aquatic exotic and native plant species richness. The aquatic exotic plant species richness is negatively correlated with the relative coverage and biomass of native plants but positively correlated with the total nitrogen (TN, total phosphorus (TP, and chemical oxygen demand (COD concentrations in the water. The native plant species richness, native species’ relative coverage, and native species’ biomass were positively related to each other, whereas the TP, TN, and COD were also positively related to each other. The native plant species richness, native species’ relative coverage, and native species biomass were each negatively correlated with the TP, TN, and COD. In addition, biotic rather than abiotic predictors accounted for most of the variation in exotic plant richness. Our results suggest that improving the vegetation coverage and the biodiversity of native plants is the most effective approach for preventing alien plant invasions and minimizing their impacts on freshwater ecosystems.

  10. Coverage of Native Plants Is Key Factor Influencing the Invasibility of Freshwater Ecosystems by Exotic Plants in China.

    Science.gov (United States)

    Yu, Haihao; Wang, Ligong; Liu, Chunhua; Fan, Shufeng

    2018-01-01

    Understanding the biotic and abiotic factors that influence the susceptibility of a community to invasion is beneficial for the prediction and management of invasive species and the conservation of native biodiversity. However, the relationships between factors and invasibility of a community have not been fully confirmed, and the factors most associated with the susceptibility of a community to invasion have rarely been identified. In this study, we investigated the species richness patterns in aquatic exotic and native plants and the relationships of exotic species richness with habitat and water environment factors in 262 aquatic plant communities in China. A total of 11 exotic plant species were recorded in our field survey, and we found neither a negative nor a positive relationship between aquatic exotic and native plant species richness. The aquatic exotic plant species richness is negatively correlated with the relative coverage and biomass of native plants but positively correlated with the total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) concentrations in the water. The native plant species richness, native species' relative coverage, and native species' biomass were positively related to each other, whereas the TP, TN, and COD were also positively related to each other. The native plant species richness, native species' relative coverage, and native species biomass were each negatively correlated with the TP, TN, and COD. In addition, biotic rather than abiotic predictors accounted for most of the variation in exotic plant richness. Our results suggest that improving the vegetation coverage and the biodiversity of native plants is the most effective approach for preventing alien plant invasions and minimizing their impacts on freshwater ecosystems.

  11. Breastfeeding in the first hour of life and modern technology: prevalence and limiting factors

    OpenAIRE

    Maria Cristina Pillegi; Adriana Policastro; Sulim Abramovici; Eduardo Cordioli; Alice D’Agostini Deutsch

    2008-01-01

    Objective: To identify the prevalence and limiting factors ofbreastfeeding in the first hour of life at the Maternity Center of HospitalIsraelita Albert Einstein, where the predominant model of childbirthcare is largely based on the use of modern technology. Methods: Aretrospective study with quantitative analysis in a middle and upperclass population of different cultural backgrounds. Data were obtainedfrom the delivery record book in a total of 12,350 births from January2004 to December 200...

  12. Hydraulic redistribution in a Mediterranean wild olive-pasture ecosystem: A key to tree survival and a limit to tree-patch size.

    Science.gov (United States)

    Curreli, Matteo; Montaldo, Nicola; Oren, Ram

    2017-04-01

    In water-limited environments, such as certain Mediterranean ecosystems, trees may survive prolonged droughts by uptake of water by dimorphic root system: deep roots, growing vertically, and shallower lateral roots, extending beyond the crown projection of tree clumps into zones of seasonal vegetative cover. In such ecosystems, therefore, the balance between soil water under tree canopy versus that in treeless patches plays a crucial role on sustaining tree physiological performance and surface water fluxes during drought periods. The study has been performed at the Orroli site, Sardinia (Italy). The landscape is covered by patchy vegetation: wild olives trees in clumps, herbaceous species, drying to bare soil in late spring. The climate is Mediterranean maritime with long droughts from May to October, and an historical mean yearly rain of about 670 mm concentrated in the autumn and winter months. Soil depth varies from 10 to 50 cm, with underlying fractured rocky layer of basalt. From 2003, a 10 meters micrometeorological tower equipped with eddy-covariance system has been used for measuring water and energy surface fluxes, as well as key state variables (e.g. leaf and soil skin temperature, radiations, air humidity and wind velocity). Soil moisture was measured with five soil water reflectometers (two below the olive canopy and three in patches with pasture vegetation alternating with bare soil in the dry season). Early analyses show that wild olive continue to transpire even as the soil dries and the pasture desiccates. In 2015, to estimate plant water use and in the context of soil water dynamic, 33 Granier-type thermal dissipation probes were installed for estimating sap flow in stems of wild olives trees, 40 cm aboveground, in representative trees over the eddy-covariance foot-print. The combined data of sap flow, soil water content, and eddy covariance, revealed hydraulic redistribution system through the plant and the soil at different layers, allowing to

  13. Uptake of inorganic phosphate is a limiting factor for Saccharomyces cerevisiae during growth at low temperatures.

    Science.gov (United States)

    Vicent, Isabel; Navarro, Alfonso; Mulet, Jose M; Sharma, Sukesh; Serrano, Ramón

    2015-05-01

    The fermenting ability of Saccharomyces at low temperatures is crucial for the development of alcoholic beverages, but the key factors for the cold tolerance of yeast are not well known. In this report, we present the results of a screening for genes able to confer cold tolerance by overexpression in a laboratory yeast strain auxotrophic for tryptophan. We identified genes of tryptophan permeases (TAT1 and TAT2), suggesting that the first limiting factor in the growth of tryptophan auxotrophic yeast at low temperatures is tryptophan uptake. This fact is of little relevance to industrial strains which are prototrophic for tryptophan. Then, we screened for genes able to confer growth at low temperatures in tryptophan-rich media and found several genes related to phosphate uptake (PHO84, PHO87, PHO90 and GTR1). This suggests that without tryptophan limitation, uptake of inorganic phosphate becomes the limiting factor. We have found that overexpression of the previously uncharacterized ORF YCR015c/CTO1 increases the uptake of inorganic phosphate. Also, genes involved in ergosterol biosynthesis (NSG2) cause improvement of growth at 10°C, dependent on tryptophan uptake, while the gluconeogenesis gene PCK1 and the proline biosynthesis gene PRO2 cause an improvement in growth at 10°C, independent of tryptophan and phosphate uptake. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. What is the most prominent factor limiting photosynthesis in different layers of a greenhouse cucumber canopy?

    Science.gov (United States)

    Chen, Tsu-Wei; Henke, Michael; de Visser, Pieter H B; Buck-Sorlin, Gerhard; Wiechers, Dirk; Kahlen, Katrin; Stützel, Hartmut

    2014-09-01

    Maximizing photosynthesis at the canopy level is important for enhancing crop yield, and this requires insights into the limiting factors of photosynthesis. Using greenhouse cucumber (Cucumis sativus) as an example, this study provides a novel approach to quantify different components of photosynthetic limitations at the leaf level and to upscale these limitations to different canopy layers and the whole plant. A static virtual three-dimensional canopy structure was constructed using digitized plant data in GroIMP. Light interception of the leaves was simulated by a ray-tracer and used to compute leaf photosynthesis. Different components of photosynthetic limitations, namely stomatal (S(L)), mesophyll (M(L)), biochemical (B(L)) and light (L(L)) limitations, were calculated by a quantitative limitation analysis of photosynthesis under different light regimes. In the virtual cucumber canopy, B(L) and L(L) were the most prominent factors limiting whole-plant photosynthesis. Diffusional limitations (S(L) + M(L)) contributed Photosynthesis in the lower canopy was more limited by the biochemical capacity, and the upper canopy was more sensitive to light than other canopy parts. Although leaves in the upper canopy received more light, their photosynthesis was more light restricted than in the leaves of the lower canopy, especially when the light condition above the canopy was poor. An increase in whole-plant photosynthesis under diffuse light did not result from an improvement of light use efficiency but from an increase in light interception. Diffuse light increased the photosynthesis of leaves that were directly shaded by other leaves in the canopy by up to 55%. Based on the results, maintaining biochemical capacity of the middle-lower canopy and increasing the leaf area of the upper canopy would be promising strategies to improve canopy photosynthesis in a high-wire cucumber cropping system. Further analyses using the approach described in this study can be expected to

  15. Towards a consistent approach for ecosystem accounting

    NARCIS (Netherlands)

    Edens, B.; Hein, L.G.

    2013-01-01

    In spite of an increasing interest in environmental economic accounting, there is still very limited experience with the integration of ecosystem services and ecosystem capital in national accounts. This paper identifies four key methodological challenges in developing ecosystem accounts: the

  16. [Limiting factors in the class III camouflage treatment: a potential protocol].

    Science.gov (United States)

    Chaques Asensi, José

    2016-06-01

    The Class III skeletal malocclusion has been traditionally treated with a combined approach of orthodontics and orthognathic surgery or with a strategy of orthodontic camouflage. Some severe cases can be identified as ideal candidates for a surgical treatment whereas some others can be handled with orthodontics alone, with a reasonable expectation of an acceptable result. However, the problem remains for the borderline patient. In fact, limited information is available in the literature regarding the identification of the factors that can help in establishing the limits for one treatment modality or the other. Furthermore, the quantification of some of these factors, for practical purposes, is practically missing or very seldom suggested. Therefore, the decision making process remains a subjective reflection based on the "good clinical sense" of the orthodontist or just reduced to an "educated guess". In order to add some information, hopefully useful in deciding the most suitable treatment option for the individual patient, we propose a clinical protocol based on four different factors. Namely: the skeletal discrepancy, the occlusal discrepancy, the periodontal condition and facial aesthetics. For each one of these factors several parameters will be evaluated and, for some of them, an attempt to provide some reference numerical values will be made. Finally, clinical examples will be presented to illustrate the concepts discussed and the treatment alternatives, final treatment plan and treatment outcome will be analyzed for each one of them. © EDP Sciences, SFODF, 2016.

  17. Comparing the demographic factors of patient with limited and diffuse type of alopecia areata

    Directory of Open Access Journals (Sweden)

    Mina Daliri

    2010-09-01

    Full Text Available Background: Alopecia areata is a chronic inflammatory disease that involves the hair follicle. Clinically, patients with alopecia areata may have patchy or confluent hair loss on the scalp or body so we conduct a study to compare the demographic aspects of patient with limited and diffuse type of alopecia areata.Materials and Method: We conducted a descriptive-analyzing study in which 306 patient were chosen. The patients were divided into two groups of diffuse and limited Alopecia. Demographic factors including age, gender, disease onset were compared in two groups. Results: Out of 306 patients, 58.8 % were male and 41.2 % were female. 247 patients (80.7% suffered from limited type and 59 patients (19.2% suffered from diffuse type. The mean age of the onset of involvement in limited group was 21.9±12 yr and 15.8±12 yr in diffuse group. The mean duration of involvement in limited group was 18.7 months and 71 months in diffuse group. Conclusion: Diffuse type alopecia areata starts at lower age and has longer duration. Our study results were similar to the others. Like other studies, thyroid disorders and atopic dermatitis are positively correlative to the severity of disease

  18. Rational stress limits and load factors for finite element analyses in pipeline applications part I - Linear elastic stress limit development

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Bisen [Stress Engineering Services, Inc. (United States)], email: Bisen.Lin@stress.com; Biel, Richard C. [Stress Engineering Services, Inc. (United States)], email: Richard.Biel@stress.com

    2010-07-01

    In the oil and gas sector, steel pipelines are the principal means used for transportation and distribution. The ASME B31 Codes provide the design margin based on the maximum principal stress theory of failure. The aim of this paper is to present the calculation of rational stress limit based on the von Mises equivalent stress for pipelines under internal pressure. Hand calculations along with finite element model analyses with the ABAQUS software were carried out for buckle arrestors and for an ASME Class 900 flange, both of which are used in an offshore natural gas pipeline. This paper provided an analytical method to determine von Mises equivalent stress limit and the stress limit value obtained has the same design margin as the ASME Codes. This method can be used to perform a finite element analysis to determine the structural integrity of a pipeline and its components; however this method does not replace any provision of ASME B31.8.

  19. Psychosocial factors at work and the development of mobility limitations among adults in Denmark

    DEFF Research Database (Denmark)

    Hansen, A. M.; Darso, L.; Manty, M.

    2014-01-01

    /never perceived the work to be meaningful (OR 6.54, 95% CI 1.55-27.55) vs. always, and who sometimes perceived high emotional demands at work (OR 7.85, 95% CI 1.78-34.65) vs. never. Among women, lower risk of incident mobility limitations was observed among those who in 2000 perceived high work pace sometimes (OR...... 0.46, 95% CI 0.24-0.87) or often (OR 0.43, 95% CI 0.22-0.85) vs. never in 2000. Also, women who always or often experienced high emotional demands had an increased risk. Conclusions: The most important finding was that high work pace was strongly associated with increased risk of mobility......Aim: Psychosocial factors in the working environment have been shown to be associated with mobility limitations, but this has not yet been confirmed in a Danish population. We aimed to examine how psychosocial factors at work are related to developing mobility limitations in Denmark. Methods...

  20. Annual ecosystem respiration variability of alpine peatland on the eastern Qinghai-Tibet Plateau and its controlling factors.

    Science.gov (United States)

    Peng, Haijun; Hong, Bing; Hong, Yetang; Zhu, Yongxuan; Cai, Chen; Yuan, Lingui; Wang, Yu

    2015-09-01

    Peatlands are widely developed in the eastern Qinghai-Tibet Plateau, but little is known about carbon budgets for these alpine peatland ecosystems. In this study, we used an automatic chamber system to measure ecosystem respiration in the Hongyuan peatland, which is located in the eastern Qinghai-Tibet Plateau. Annual ecosystem respiration measurements showed a typical seasonal pattern, with the peak appearing in June. The highest respiration was 10.43 μmol CO2/m(2)/s, and the lowest was 0.20 μmol CO2/m(2)/s. The annual average ecosystem respiration was 2.06 μmol CO2/m(2)/s. The total annual respiration was 599.98 g C/m(2), and respiration during the growing season (from May to September) accounted for 78 % of the annual sum. Nonlinear regression revealed that ecosystem respiration has a significant exponential correlation with soil temperature at 10-cm depth (R (2) = 0.98). The Q 10 value was 3.90, which is far higher than the average Q 10 value of terrestrial ecosystems. Ecosystem respiration had an apparent diurnal variation pattern in growing season, with peaks and valleys appearing at approximately 14:00 and 10:00, respectively, which could be explained by soil temperature and soil water content variation at 10-cm depth.

  1. Fruitful factors: what limits seed production of flowering plants in the alpine?

    Science.gov (United States)

    Straka, Jason R; Starzomski, Brian M

    2015-05-01

    Predicting demographic consequences of climate change for plant communities requires understanding which factors influence seed set, and how climate change may alter those factors. To determine the effects of pollen availability, temperature, and pollinators on seed production in the alpine, we combined pollen-manipulation experiments with measurements of variation in temperature, and abundance and diversity of potential pollinators along a 400-m elevation gradient. We did this for seven dominant species of flowering plants in the Coast Range Mountains, British Columbia, Canada. The number of viable seeds set by plants was influenced by pollen limitation (quantity of pollen received), mate limitation (quality of pollen), temperature, abundance of potential pollinators, seed predation, and combinations of these factors. Early flowering species (n = 3) had higher seed set at high elevation and late-flowering species (n = 4) had higher seed set at low elevation. Degree-days >15 °C were good predictors of seed set, particularly in bee-pollinated species, but had inconsistent effects among species. Seed production in one species, Arnica latifolia, was negatively affected by seed-predators (Tephritidae) at mid elevation, where there were fewer frost-hours during the flowering season. Anemone occidentalis, a fly-pollinated, self-compatible species had high seed set at all elevations, likely due to abundant potential pollinators. Simultaneously measuring multiple factors affecting reproductive success of flowering plants helped identify which factors were most important, providing focus for future studies. Our work suggests that responses of plant communities to climate change may be mediated by flowering time, pollination syndrome, and susceptibility to seed predators.

  2. Factors Limiting Adoption of Technologies by Farmers in Catabola Municipality, Angola

    Directory of Open Access Journals (Sweden)

    Rušarová K.

    2016-06-01

    Full Text Available The objective of the paper is to define the factors influencing the adoption of animal traction and/or mechanical-power technology in the conditions of Catabola municipality where hand-tool technology is being used on 99.7% of the area cultivated by small farmers. Primary data collection was conducted in the period July–August 2011; semi-structured questionnaires and focus group discussions were the most frequent methods used. In total, 151 small-scale farmers from 9 villages participated in the survey. Ten factors influencing the dependent variable – level of technology used by farmers in combination with hiring of labour – were defined. The factors were statistically analyzed by ANOVA. The area of cultivated land and the educational level of both parents and children were found to be the factors limiting the process of animal traction or mechanical power adoption by small farmers in the Catabola municipality. In addition, a relatively high rate of child labour was observed. With the exclusion of childless families, 62.7% of small farmer families regularly use children aged 0–14 years for field operations. The results confirm that the factor of hiring extra labour is irrelevant in determining the development in technology use by small farmers in the Catabola municipality.

  3. Operationalizing ecosystem-based adaptation: harnessing ecosystem services to buffer communities against climate change

    Directory of Open Access Journals (Sweden)

    Christine Wamsler

    2016-03-01

    Full Text Available Ecosystem-based approaches for climate change adaptation are promoted at international, national, and local levels by both scholars and practitioners. However, local planning practices that support these approaches are scattered, and measures are neither systematically implemented nor comprehensively reviewed. Against this background, this paper advances the operationalization of ecosystem-based adaptation by improving our knowledge of how ecosystem-based approaches can be considered in local planning (operational governance level. We review current research on ecosystem services in urban areas and examine four Swedish coastal municipalities to identify the key characteristics of both implemented and planned measures that support ecosystem-based adaptation. The results show that many of the measures that have been implemented focus on biodiversity rather than climate change adaptation, which is an important factor in only around half of all measures. Furthermore, existing measures are limited in their focus regarding the ecological structures and the ecosystem services they support, and the hazards and risk factors they address. We conclude that a more comprehensive approach to sustainable ecosystem-based adaptation planning and its systematic mainstreaming is required. Our framework for the analysis of ecosystem-based adaptation measures proved to be useful in identifying how ecosystem-related matters are addressed in current practice and strategic planning, and in providing knowledge on how ecosystem-based adaptation can further be considered in urban planning practice. Such a systematic analysis framework can reveal the ecological structures, related ecosystem services, and risk-reducing approaches that are missing and why. This informs the discussion about why specific measures are not considered and provides pathways for alternate measures/designs, related operations, and policy processes at different scales that can foster sustainable

  4. Interleukin-17 limits hypoxia-inducible factor 1α and development of hypoxic granulomas during tuberculosis.

    Science.gov (United States)

    Domingo-Gonzalez, Racquel; Das, Shibali; Griffiths, Kristin L; Ahmed, Mushtaq; Bambouskova, Monika; Gopal, Radha; Gondi, Suhas; Muñoz-Torrico, Marcela; Salazar-Lezama, Miguel A; Cruz-Lagunas, Alfredo; Jiménez-Álvarez, Luis; Ramirez-Martinez, Gustavo; Espinosa-Soto, Ramón; Sultana, Tamanna; Lyons-Weiler, James; Reinhart, Todd A; Arcos, Jesus; de la Luz Garcia-Hernandez, Maria; Mastrangelo, Michael A; Al-Hammadi, Noor; Townsend, Reid; Balada-Llasat, Joan-Miquel; Torrelles, Jordi B; Kaplan, Gilla; Horne, William; Kolls, Jay K; Artyomov, Maxim N; Rangel-Moreno, Javier; Zúñiga, Joaquín; Khader, Shabaana A

    2017-10-05

    Mycobacterium tuberculosis (Mtb) is a global health threat, compounded by the emergence of drug-resistant strains. A hallmark of pulmonary tuberculosis (TB) is the formation of hypoxic necrotic granulomas, which upon disintegration, release infectious Mtb. Furthermore, hypoxic necrotic granulomas are associated with increased disease severity and provide a niche for drug-resistant Mtb. However, the host immune responses that promote the development of hypoxic TB granulomas are not well described. Using a necrotic Mtb mouse model, we show that loss of Mtb virulence factors, such as phenolic glycolipids, decreases the production of the proinflammatory cytokine IL-17 (also referred to as IL-17A). IL-17 production negatively regulates the development of hypoxic TB granulomas by limiting the expression of the transcription factor hypoxia-inducible factor 1α (HIF1α). In human TB patients, HIF1α mRNA expression is increased. Through genotyping and association analyses in human samples, we identified a link between the single nucleotide polymorphism rs2275913 in the IL-17 promoter (-197G/G), which is associated with decreased IL-17 production upon stimulation with Mtb cell wall. Together, our data highlight a potentially novel role for IL-17 in limiting the development of hypoxic necrotic granulomas and reducing disease severity in TB.

  5. Sensory shelf-life limiting factor of high hydrostatic pressure processed avocado paste.

    Science.gov (United States)

    Jacobo-Velázquez, D A; Hernández-Brenes, C

    2011-08-01

    High hydrostatic pressure (HHP) processing pasteurizes avocado paste without a significant impact on flavor. Although HHP-treated avocado paste stored under refrigeration is safe for human consumption for months, sensory changes taking place during storage cause the rejection of the product by consumers within days. Although it is known that the shelf life of the product ends before its microbial counts are high, its sensory shelf life limiting factor remains unknown. The present study focused on the use of a trained panel and a consumer panel to determine the sensory shelf life limiting factor of HHP-treated avocado paste. The trained panel identified sour and rancid flavors as the main sensory descriptors (critical descriptors) that differentiated stored from freshly processed samples. Further data obtained from consumers identified sour flavor as the main cause for a significant decrease in the acceptability (shelf life limiting factor) of refrigerated HHP-treated avocado paste. The study allowed the elucidation of a proposed deterioration mechanism for HHP-treated avocado paste during its refrigerated shelf life. The information through this work enhances scientific knowledge of the product and proposes the sour flavor development during storage as a relevant sensory attribute that needs to be improved in order to enhance the product shelf life. At present, HHP is the most effective commercial nonthermal technology to process avocado paste when compared to thermal and chemical alternatives. HHP-treated avocado paste is a microbiologically stable food for a period of at least 45 d stored under refrigeration. However, previous published work indicated that consumers rejected the product after approximately 19 d of storage due to sensory changes. This manuscript presents a sensory study that permitted the identification of the critical sensory descriptor that is acting as the sensory shelf life limiting factor of the product. The data presented herein along with

  6. The predictive factors of diplopia and extraocular movement limitations in isolated pure blow-out fracture.

    Science.gov (United States)

    Kasaee, Abolfazl; Mirmohammadsadeghi, Arash; Kazemnezhad, Fatemeh; Eshraghi, Bahram; Akbari, Mohammad Reza

    2017-03-01

    To evaluate the predictive factors for development of diplopia and extraocular muscle movement (EOM) limitations in the patients with isolated pure blow-out fracture. One hundred thirty-two patients with isolated pure blow-out fracture were included. The diagnosis was done with computed tomography scan. Possible predictive factors were analyzed with logistic regression. The cases that underwent surgery were assigned in the surgical group, and other cases were assigned in the non-surgical group. Receiver operating characteristic (ROC) curve analysis was used in the surgical group to evaluate the power of time interval from trauma to the surgery to predict persistence of 6 months postoperative diplopia and EOM limitation. At the first visit, 45 of 60 cases (75%) in the surgical group and 15 of 72 cases (20.8%) in the nonsurgical group had diplopia. After 6 months follow-up, 7 cases (11.7%) in the surgical group and 1 case (1.4%) in the nonsurgical group had persistent diplopia. Type of fracture was significantly associated with first visit diplopia (P = 0.01) and EOM limitations (P = 0.06). In the surgical group, type of fracture (P = 0.02 for both) and time interval from trauma to the surgery (P = 0.006 and 0.004, respectively) were significantly associated with 1 month diplopia and EOM limitations. Only time interval from trauma to the surgery (P = 0.04) was significantly associated with 3 months EOM limitation. In the ROC curve analysis, if the surgery was done before 4.5 (sensitivity = 87.5% and specificity = 61.3%) and 7.5 (sensitivity = 87.5% and specificity = 66.9%) days, risk of 6 months postoperative diplopia and EOM limitation was reduced, respectively. In the early postoperative period, a higher rate of diplopia was observed in the patients with combined inferior and medial wall fractures and longer time intervals from trauma to the surgery. The best time for blow-out fracture surgery was within 4.5 days after the trauma.

  7. Modeling Nitrous Oxide emissions and identifying emission controlling factors for a spruce forest ecosystem on drained organic soil

    Science.gov (United States)

    He, Hongxing; Kasimir, Åsa; Jansson, Per-Erik; Svensson, Magnus; Meyer, Astrid; Klemedtsson, Leif

    2015-04-01

    High Nitrous Oxide (N2O) emission has been identified in hemiboreal forests on drained organic soils. However, the controlling factors regulating the emissions have been unclear. To examine the importance of different factors on the N2O emission in a spruce forest on drained organic soil, a process-based model, CoupModel, was calibrated by the generalized likelihood uncertainty estimation (GLUE) method. The calibrated model reproduced most of the high resolution data (total net radiation, soil temperature, groundwater level, net ecosystem exchange, etc.) very well, as well as accumulated measured N2O emissions, but showed difficulties to capture all the measured emission peaks. Parameter uncertainties could be reduced by combining selected criteria with the measurement data. The model showed the N2O emissions during the summer to be controlled mainly by the competition between plants and microbes while during the winter season snow melt periods are important. The simulated N budget shows >100 kg N ha-1 yr-1 to be in circulation between soil and plants and back again. Each year the peat mineralization adds about 60 kg N ha-1 and atmospheric deposition 12 kg N ha-1. Most of the mineralized litter and peat N is directly taken up by the plants but only a part accumulates in the plant biomass. As long as no timber is harvested the main N loss from the system is through nitrate leaching (30 kg N ha-1 yr-1) and gas emissions (20 kg N ha-1 yr-1), 55% as NO, 27% as N2O and 18% as N2. Regarding N2O gas emissions, our modeling indicates denitrification to be the most responsible process, of the size 6 kg N ha-1 yr-1, which could be compared to 0.04 kg N ha-1 yr-1 from nitrification. Our modelling also reveal 88% of the N2O mainly to be produced by denitrification in the capillary fringe (c.a. 40-60 cm below soil surface) of the anaerobic zone using nitrate produced in the upper more aerobic layers. We conclude N2O production/emission to be controlled mainly by the complex

  8. Factors limiting deceased organ donation: focus groups' perspective from culturally diverse community.

    Science.gov (United States)

    Wong, L P

    2010-06-01

    In-depth understanding of cultural and religious factors limiting organ donation of three ethnic populations (Malay, Chinese, and Indian) in Southeast Asia is lacking. Identification of factors limiting organ donation among these three ethnic groups will provide insights into culturally appropriate strategies to promote acceptance of organ donation in a multiethnic Asian community. A total of 17 focus group discussions (105 participants) were conducted between September and December 2008. Participants were members of the general public aged 18 to 60 years, recruited through convenient sampling around the Klang Valley area of Malaysia. Although the majority had favorable attitudes toward deceased organ donation and transplantation, a diversity of myths and misinformation were unearthed from the discussions across the ethnic groups. These include perceived religious prohibition, cultural myths and misperceptions, fear of disfigurement, fear of surgery, distrust of the medical system, and family disapproval. Culture and religious beliefs played important prohibitive roles among those opposed to organ donations. There were distinctive ethnic differences in cultural and religious concerns regarding organ donation. Less-educated and rural groups appeared to have more misconceptions than the well-educated and the urban groups. Our findings may assist organ donation and transplantation organizations to reach diverse sociodemographic and ethnic communities with culture-specific information about organ donation. The involvement of community and religious leaders is critical in organ donation requests.

  9. Supply of fatty acid is one limiting factor in the accumulation of triacylglycerol in developing embryos

    Energy Technology Data Exchange (ETDEWEB)

    Bao, X.; Ohlrogge, J.

    1999-08-01

    The metabolic factors that determine oil yield in seeds are still not well understood. To begin to examine the limits on triacylglycerol (TAG) production, developing Cuphea lanceolata, Ulmus carpinifolia, and Ulmus parvifolia embryos were incubated with factors whose availability might limit oil accumulation. The addition of glycerol or sucrose did not significantly influence the rate of TAG synthesis. However, the rate of {sup 14}C-TAG synthesis upon addition of 2.1 mM {sup 14}C-decanoic acid (10:0) was approximately four times higher than the in vivo rate of TAG accumulation in C. lanceolata and two times higher than the in vivo rate in U. carpinifolia and U. parvifolia. In C. lanceolata embryos, the highest rate of {sup 14}C-TAG synthesis (14.3 nmol h{sup {minus}1} embryo {sup {minus}1}) was achieved with the addition of 3.6 mM decanoic acid. {sup 14}C-Decanoic acid was incorporated equally well in all three acyl positions of TAG. The results suggest that C. lancelata, U. Carpinifolia, and U. parvifolia embryos have sufficient acyltransferase activities and glycerol-3-phosphate levels to support rates of TAG synthesis in excess of those found in vivo. Consequently, the amount of TAG synthesized in these oilseeds may be in part determined by the amount of fatty acid produced in plastids.

  10. Limiting Factors of Brain Donation in Neurodegenerative Diseases: The Example of French Memory Clinics.

    Science.gov (United States)

    Le Bouc, Raphael; Marelli, Cecilia; Beaufils, Emilie; Berr, Claudine; Hommet, Caroline; Touchon, Jacques; Pasquier, Florence; Deramecourt, Vincent

    2016-01-01

    Postmortem neuropathological examination of the brain is essential in neurodegenerative diseases, to ensure accurate diagnosis, to obtain an a posteriori critical assessment of the adequacy of clinical care, and to validate new biomarkers, but is only rarely performed. The purpose of this study was to assess factors limiting brain donation, such as reluctance of physicians to seek donation consent, opposition from patients and families, and organizational constraints. We conducted a survey across French memory clinics and major neuropathological centers. Few postmortem examinations were performed annually, as less than one third of the centers had performed at least five autopsies, and 41% had performed none. The main limiting factor was the lack of donation requests made by physicians, as half of them never approach patients for brain donation. Reasons for not seeking donation consent often include discomfort broaching the subject and lack of awareness of the medical and scientific benefit of postmortems (77%), organizational constraints (61%), and overestimation of families' negative reaction (51%). Family refusals represented a second major obstacle, and were often caused by misconceptions. Identifying and addressing these biases early could help improve physicians' rate of making requests and the public's awareness about the importance of brain donation.

  11. Influencing factors for household water quality improvement in reducing diarrhoea in resource-limited areas.

    Science.gov (United States)

    Zin, Thant; Mudin, Kamarudin D; Myint, Than; Naing, Daw K S; Sein, Tracy; Shamsul, B S

    2013-01-01

    Water and sanitation are major public health issues exacerbated by rapid population growth, limited resources, disasters and environmental depletion. This study was undertaken to study the influencing factors for household water quality improvement for reducing diarrhoea in resource-limited areas. Data were collected from articles and reviews from relevant randomized controlled trials, new articles, systematic reviews and meta-analyses from PubMed, World Health Organization (WHO), United Nations Children's Fund (UNICEF) and WELL Resource Centre For Water, Sanitation And Environmental Health. Water quality on diarrhoea prevention could be affected by contamination during storage, collection and even at point-of-use. Point-of-use water treatment (household-based) is the most cost-effective method for prevention of diarrhoea. Chemical disinfection, filtration, thermal disinfection, solar disinfection and flocculation and disinfection are five most promising household water treatment methodologies for resource-limited areas. Promoting household water treatment is most essential for preventing diarrhoeal disease. In addition, the water should be of acceptable taste, appropriate for emergency and non-emergency use.

  12. Rate limiting factors in trichloroethylene co-metabolic degradation by phenol-grown aerobic granules.

    Science.gov (United States)

    Zhang, Yi; Tay, Joo Hwa

    2014-04-01

    The potential of aerobic granular sludge in co-metabolic removal of recalcitrant substances was evaluated using trichloroethylene (TCE) as the model compound. Aerobic granules cultivated in a sequencing batch reactor with phenol as the growth substrate exhibited TCE and phenol degradation activities lower than previously reported values. Depletion of reducing energy and diffusion limitation within the granules were investigated as the possible rate limiting factors. Sodium formate and citrate were supplied to the granules in batch studies as external electron sources. No significant enhancing effect was observed on the instant TCE transformation rates, but 10 mM formate could improve the ultimate transformation capacity by 26 %. Possible diffusion barrier was studied by sieving the biomass into five size fractions, and determining their specific TCE and phenol degradation rates and capacities. Biomass in the larger size fractions generally showed lower activities. Large granules of >700 μm diameter exhibited only 22 % of the flocs' TCE transformation capacity and 35 % of its phenol dependent SOUR, indicating the possible occurrence of diffusion limitation in larger biomass. However, the highest specific TCE transformation rate was observed with the fraction that mostly consisted of small granules (150-300 μm), suggesting an optimal size range while applying aerobic granules in TCE co-metabolic removal.

  13. Ecosystem CO2/H2O fluxes are explained by hydraulically limited gas exchange during tree mortality from spruce bark beetles

    Science.gov (United States)

    Frank, John M.; Massman, William J.; Ewers, Brent E.; Huckaby, Laurie S.; Negrón, José F.

    2014-06-01

    Disturbances are increasing globally due to anthropogenic changes in land use and climate. This study determines whether a disturbance that affects the physiology of individual trees can be used to predict the response of the ecosystem by weighing two competing hypothesis at annual time scales: (a) changes in ecosystem fluxes are proportional to observable patterns of mortality or (b) to explain ecosystem fluxes the physiology of dying trees must also be incorporated. We evaluate these hypotheses by analyzing 6 years of eddy covariance flux data collected throughout the progression of a spruce beetle (Dendroctonus rufipennis) epidemic in a Wyoming Engelmann spruce (Picea engelmannii)-subalpine fir (Abies lasiocarpa) forest and testing for changes in canopy conductance (gc), evapotranspiration (ET), and net ecosystem exchange (NEE) of CO2. We predict from these hypotheses that (a) gc, ET, and NEE all diminish (decrease in absolute magnitude) as trees die or (b) that (1) gc and ET decline as trees are attacked (hydraulic failure from beetle-associated blue-stain fungi) and (2) NEE diminishes both as trees are attacked (restricted gas exchange) and when they die. Ecosystem fluxes declined as the outbreak progressed and the epidemic was best described as two phases: (I) hydraulic failure caused restricted gc, ET (28 ± 4% decline, Bayesian posterior mean ± standard deviation), and gas exchange (NEE diminished 13 ± 6%) and (II) trees died (NEE diminished 51 ± 3% with minimal further change in ET to 36 ± 4%). These results support hypothesis b and suggest that model predictions of ecosystem fluxes following massive disturbances must be modified to account for changes in tree physiological controls and not simply observed mortality.

  14. 23 CFR 636.302 - Are there any limitations on the selection and use of proposal evaluation factors?

    Science.gov (United States)

    2010-04-01

    ... Are there any limitations on the selection and use of proposal evaluation factors? (a) The selection... 23 Highways 1 2010-04-01 2010-04-01 false Are there any limitations on the selection and use of proposal evaluation factors? 636.302 Section 636.302 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF...

  15. Trait Mindfulness as a Limiting Factor for Residual Depressive Symptoms: An Explorative Study Using Quantile Regression

    Science.gov (United States)

    Radford, Sholto; Eames, Catrin; Brennan, Kate; Lambert, Gwladys; Crane, Catherine; Williams, J. Mark G.; Duggan, Danielle S.; Barnhofer, Thorsten

    2014-01-01

    Mindfulness has been suggested to be an important protective factor for emotional health. However, this effect might vary with regard to context. This study applied a novel statistical approach, quantile regression, in order to investigate the relation between trait mindfulness and residual depressive symptoms in individuals with a history of recurrent depression, while taking into account symptom severity and number of episodes as contextual factors. Rather than fitting to a single indicator of central tendency, quantile regression allows exploration of relations across the entire range of the response variable. Analysis of self-report data from 274 participants with a history of three or more previous episodes of depression showed that relatively higher levels of mindfulness were associated with relatively lower levels of residual depressive symptoms. This relationship was most pronounced near the upper end of the response distribution and moderated by the number of previous episodes of depression at the higher quantiles. The findings suggest that with lower levels of mindfulness, residual symptoms are less constrained and more likely to be influenced by other factors. Further, the limiting effect of mindfulness on residual symptoms is most salient in those with higher numbers of episodes. PMID:24988072

  16. Prognostic factors for patients with inoperable non-small cell lung cancer, limited disease

    International Nuclear Information System (INIS)

    Kaasa, S.; Mastekaasa, A.; Lund, E.

    1989-01-01

    In a prospective controlled clinical trial, 102 patients with inoperable non-small lung cancer (NSCLC), limited disease, stage II and III were treated with combination chemotherapy, cisplatin 70 mg/m 2 i.v. on day one and etoposide 100 mg/m 2 i.v. on day one, and etoposide 200 mg/m 2 orally on days 2 and 3, or radiotherapy given in 15 fractions of 2.8 Gy with two anterior/posterior fields during a period of three weeks. The patients completed a validated self-administered questionnaire before the start of treatment that assessed their psychosocial well-being, disease-related symptoms, personal functioning, and every day activity. These subjective varibles were evaluated together with treatment modality, WHO performance status, weight loss, and stage of disease, with regard to their value in predicting survival. Univariate survival analyses were undertaken for each individual factor, median survival was calculated according to life-table analyses. A step-wise multiple regression analysis was used to measure the prognostic value of the various factors. In the univariate analysis, general symptons (p=0.0006) psychosocial well-being (p=0.0002) and stage of disease (p=0.007) were the best predictive factors. In the multiple regression analyses the subjective variables, general symptons (p<0.01) and psychosocial well-being (p<0.05) were shown to have the best predictive value for the patients' survival. (author). 20 refs.; 4 figs.; 3 tabs

  17. Transfer factor of caesium-137 in natural and agricultural grass ecosystems in the area of Plavsk radioactive spot, Russia

    Energy Technology Data Exchange (ETDEWEB)

    Paramonova, Tatiana A.; Machaeva, Ekaterina N. [Radioecology and Ecotoxicology Department of Soil Science Faculty, Lomonosov Moscow State University, 119234 Moscow (Russian Federation); Belyaev, Vladimir R. [Laboratory of soil erosion and fluvial processes of Geography Faculty, Lomonosov Moscow State University, 119234 Moscow (Russian Federation)

    2014-07-01

    Root uptake and translocation of ¹³⁷Cs from soil to plant is the key for estimation of general ecological situation and land use on radioactive contaminated territories. There are numerous researches concerning the relationship between the level of the radionuclide presence in soils and its accumulation in vegetation that usually describes as transfer factor (TF) for ¹³⁷Cs (the ratio of the specific ¹³⁷Cs activity in the plant tissue and the soil). But in most cases only edible organs or above-ground parts of plants are taken into account in evaluating TF. It is reasonable from the standpoint of practical use, but does not provide accurate information in the study of ¹³⁷Cs biogeochemical cycle features. The study of the ¹³⁷Cs root uptake from the radioactive contaminated chernozem soil and its distribution between above-ground and below-ground fractions of grass vegetation was conducted in the natural conditions on the territory of Plavsk radioactive spot (Tula region, Russia)~25 years after Chernobyl accident. The main crops of field rotation in this landscape (wheat, barley, potatoes, rape, maize) which occupy watersheds and slopes with arable chernozems contaminated at a level 460-670 Bq/kg (170-220 kBq/m²) and natural grassland ecosystems which occupy lower parts of slopes and flood plains with dry and wet meadows contaminated at a level 620-710 Bq/kg (210-250 kBq/m²) were examined. Total accumulation of ¹³⁷Cs in vegetation strongly depends on the level of soil radioactive contamination (correlation coefficient 0.87). So specific ¹³⁷Cs activity in vegetation of meadows (103-160 Bq/kg) in general more than one in agricultural crops (9-92 Bq/kg). Other reason may be the predominance of perennial herbs in natural meadows whereas agricultural systems contain annual crops. The values of ¹³⁷Cs TF in the studied ecosystems vary within a relatively narrow range: from 0.01 (rape) to 0.20 (wet meadow), that confirms the discrimination of

  18. The course of limitations in activities over 5 years in patients with knee and hip osteoarthritis with moderate functional limitations: risk factors for future functional decline.

    NARCIS (Netherlands)

    Pisters, M.F.; Veenhof, C.; Dijk, G.M. van; Heymans, M.W.; Twisk, J.W.R.; Dekker, J.

    2012-01-01

    Method: A longitudinal cohort study with 5 years follow-up was conducted. Patients (n = 288) were recruited at rehabilitation centers and hospitals. The main outcome measures were self-reported and performance-based limitations in activities. Prognostic factors were demographic and clinical data,

  19. Ecosystem Vulnerability Review: Proposal of an Interdisciplinary Ecosystem Assessment Approach.

    Science.gov (United States)

    Weißhuhn, Peter; Müller, Felix; Wiggering, Hubert

    2018-03-14

    To safeguard the sustainable use of ecosystems and their services, early detection of potentially damaging changes in functional capabilities is needed. To support a proper ecosystem management, the analysis of an ecosystem's vulnerability provide information on its weaknesses as well as on its capacity to recover after suffering an impact. However, the application of the vulnerability concept to ecosystems is still an emerging topic. After providing background on the vulnerability concept, we summarize existing ecosystem vulnerability research on the basis of a systematic literature review with a special focus on ecosystem type, disciplinary background, and more detailed definition of the ecosystem vulnerability components. Using the Web of Science TM Core Collection, we overviewed the literature from 1991 onwards but used the 5 years from 2011 to 2015 for an in-depth analysis, including 129 articles. We found that ecosystem vulnerability analysis has been applied most notably in conservation biology, climate change research, and ecological risk assessments, pinpointing a limited spreading across the environmental sciences. It occurred primarily within marine and freshwater ecosystems. To avoid confusion, we recommend using the unambiguous term ecosystem vulnerability rather than ecological, environmental, population, or community vulnerability. Further, common ground has been identified, on which to define the ecosystem vulnerability components exposure, sensitivity, and adaptive capacity. We propose a framework for ecosystem assessments that coherently connects the concepts of vulnerability, resilience, and adaptability as different ecosystem responses. A short outlook on the possible operationalization of the concept by ecosystem vulnerabilty indices, and a conclusion section complete the review.

  20. Ecosystem Jenga!

    Science.gov (United States)

    Umphlett, Natalie; Brosius, Tierney; Laungani, Ramesh; Rousseau, Joe; Leslie-Pelecky, Diandra L.

    2009-01-01

    To give students a tangible model of an ecosystem and have them experience what could happen if a component of that ecosystem were removed; the authors developed a hands-on, inquiry-based activity that visually demonstrates the concept of a delicately balanced ecosystem through a modification of the popular game Jenga. This activity can be…

  1. Acidosis as a factor limiting muscular activity during physical exercise and mechanisms for its development

    Directory of Open Access Journals (Sweden)

    Rozenfeld Aleksandr

    2016-06-01

    Full Text Available Based on the analysis of published data, it was shown that metabolic acidosis is an attribute of many extreme physiological and pathological conditions. It was found that metabolic acidosis is the main factor responsible for the fatigue and performance limitations during intense physical activities. According to prevailing views, metabolic acidosis during intense physical exertion is caused by the activation of glycolysis is due to insufficient activity of oxygen-dependent energy supply. However, the development and the degree of acidosis depend on whether the energy source that produces ATP consumes protons or release protons. Theoretical analysis of the published data that was performed in the study suggests that the cause of the acidosis is not the accumulation of insufficiently oxidized intermediate metabolites such as lactate and pyruvate, but hydrolysis of the ATP molecules, the resynthesis of which is not offset by oxidative phosphorylation.

  2. Limited-information goodness-of-fit testing of hierarchical item factor models.

    Science.gov (United States)

    Cai, Li; Hansen, Mark

    2013-05-01

    In applications of item response theory, assessment of model fit is a critical issue. Recently, limited-information goodness-of-fit testing has received increased attention in the psychometrics literature. In contrast to full-information test statistics such as Pearson's X(2) or the likelihood ratio G(2) , these limited-information tests utilize lower-order marginal tables rather than the full contingency table. A notable example is Maydeu-Olivares and colleagues'M2 family of statistics based on univariate and bivariate margins. When the contingency table is sparse, tests based on M2 retain better Type I error rate control than the full-information tests and can be more powerful. While in principle the M2 statistic can be extended to test hierarchical multidimensional item factor models (e.g., bifactor and testlet models), the computation is non-trivial. To obtain M2 , a researcher often has to obtain (many thousands of) marginal probabilities, derivatives, and weights. Each of these must be approximated with high-dimensional numerical integration. We propose a dimension reduction method that can take advantage of the hierarchical factor structure so that the integrals can be approximated far more efficiently. We also propose a new test statistic that can be substantially better calibrated and more powerful than the original M2 statistic when the test is long and the items are polytomous. We use simulations to demonstrate the performance of our new methods and illustrate their effectiveness with applications to real data. © 2012 The British Psychological Society.

  3. Searching out the hydrogen absorption/desorption limiting reaction factors: Strategies allowing to increase kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Zeaiter, Ali, E-mail: ali.zeaiter@femto-st.fr; Chapelle, David; Nardin, Philippe

    2015-10-05

    Highlights: • A macro scale thermodynamic model that simulates the response of a FeTi-X hydride tank is performed, and validated experimentally. • A sensibility study to identify the most influent input variables that can changes very largely the reaction rate. - Abstract: Hydrogen gas has become one of the most promising energy carriers. Main breakthrough concerns hydrogen solid storage, specially based on intermetallic material use. Regarding the raw material abundance and cost, the AB type alloy FeTi is an auspicious candidate to store hydrogen. Its absorption/desorption kinetics is a basic hindrance to common use, compared with more usual hydrides. First, discussions based on literature help us identifying the successive steps leading to metal hydriding, and allow to introduce the physical parameters which drive or limit the reaction. This analysis leads us to suggest strategies in order to increase absorption/desorption kinetics. Attention is then paid to a thermofluidodynamic model, allowing to describe a macroscopic solid storage reactor. Thus, we can achieve a simulation which describes the overall reaction inside the hydrogen reactor and, by varying the sub-mentioned parameters (thermal conductivity, the powder granularity, environment heat exchange…), we attempt to hierarchy the reaction limiting factors. These simulations are correlated to absorption/desorption experiments for which pressure, temperature and hydrogen flow are recorded.

  4. Factors Limiting Formation of Community Forestry Enterprises in the Southern Mixteca Region of Oaxaca, Mexico

    Science.gov (United States)

    Hernández-Aguilar, José Antonio; Cortina-Villar, Héctor Sergio; García-Barrios, Luis Enrique; Castillo-Santiago, Miguel Ángel

    2017-03-01

    Many studies have considered community-based forestry enterprises to be the best option for development of rural Mexican communities with forests. While some of Mexico's rural communities with forests receive significant economic and social benefits from having a community forestry enterprise, the majority have not formed such enterprises. The purpose of this article is to identify and describe factors limiting the formation of community forestry enterprise in rural communities with temperate forests in the Southern Mixteca region of Oaxaca, Mexico. The study involved fieldwork, surveys applied to Community Board members, and maps developed from satellite images in order to calculate the forested surface area. It was found that the majority of Southern Mixteca communities lack the natural and social conditions necessary for developing community forestry enterprise; in this region, commercial forestry is limited due to insufficient precipitation, scarcity of land or timber species, community members' wariness of commercial timber extraction projects, ineffective local governance, lack of capital, and certain cultural beliefs. Only three of the 25 communities surveyed have a community forestry enterprise; however, several communities have developed other ways of profiting from their forests, including pine resin extraction, payment for environmental services (PES), sale of spring water, and ecotourism. We conclude that community forestry enterprise are not the only option for rural communities to generate income from their forests; in recent years a variety of forest-related economic opportunities have arisen which are less demanding of communities' physical and social resources.

  5. Risk and resiliency factors influencing onset and adolescence-limited commercial sexual exploitation of disadvantaged girls.

    Science.gov (United States)

    Reid, Joan A

    2014-12-01

    Previous research into age-related variables relevant to girls and young women being involved in commercial sexual exploitation (including prostitution) has not distinguished between its onset and limitation to adolescence and its early onset and persistence into adult life. The aims of this study were to examine variables associated with adolescent versus adult onset of commercial sexual exploitation and identify potential risk and resiliency factors differentiating adolescence-limited sexual exploitation and early-onset-adult persistent exploitation. Interviews with 174 vulnerable mostly African-American women, 23% of whom reported commercial sexual exploitation in adolescence and/or adulthood, yielded data, which were analysed using multinomial logistic regressions. Adolescent sexual victimisation, younger age at first alcohol/drug use, being a victim of intimate partner violence and sense of stigmatisation of sexual self/others were all variables associated with adolescent onset of commercial sexual exploitation. Educational attainment differentiated adolescence limited from adolescent-adult persistent exploitation; exploitation had ceased by adulthood among over two-thirds of those who completed at least high school education, but only 13% of those exploited into adult life had finished high school. As level of education was linked to cessation of exploitation by adulthood, support for vulnerable girls to complete education at least to high school level may be protective.The link between early onset of substance misuse and persistent exploitation suggests that education and support specifically targeted within this field could reduce likelihood of persistent abuse.Work directed at improvement of self-image may also reduce risk of persistent exploitation. Copyright © 2014 John Wiley & Sons, Ltd.

  6. Mangrove ecosystems under climate change

    Science.gov (United States)

    Jennerjahn, T.C.; Gilman, E.; Krauss, Ken W.; Lacerda, L.D.; Nordhaus, I.; Wolanski, E.

    2017-01-01

    This chapter assesses the response of mangrove ecosystems to possible outcomes of climate change, with regard to the following categories: (i) distribution, diversity, and community composition, (ii) physiology of flora and fauna, (iii) water budget, (iv) productivity and remineralization, (v) carbon storage in biomass and sediments, and (vi) the filter function for elements beneficial or harmful to life. These categories are then used to identify the regions most vulnerable to climate change. The four most important factors determining the response of mangrove ecosystems to climate change are sea level rise, an increase in frequency and/or intensity of storms, increases in temperature, and aridity. While these changes may be beneficial for some mangrove forests at latitudinal distribution limits, they will threaten forest structure and functions and related ecosystem services in most cases. The interaction of climate change with human interventions is discussed, as well as the effects on ecosystem services including possible adaptation and management options. The chapter closes with an outlook on knowledge gaps and priority research needed to fill these gaps.

  7. Divergence of dominant factors in soil microbial communities and functions in forest ecosystems along a climatic gradient

    Science.gov (United States)

    Xu, Zhiwei; Yu, Guirui; Zhang, Xinyu; He, Nianpeng; Wang, Qiufeng; Wang, Shengzhong; Xu, Xiaofeng; Wang, Ruili; Zhao, Ning

    2018-03-01

    Soil microorganisms play an important role in regulating nutrient cycling in terrestrial ecosystems. Most of the studies conducted thus far have been confined to a single forest biome or have focused on one or two controlling factors, and few have dealt with the integrated effects of climate, vegetation, and soil substrate availability on soil microbial communities and functions among different forests. In this study, we used phospholipid-derived fatty acid (PLFA) analysis to investigate soil microbial community structure and extracellular enzymatic activities to evaluate the functional potential of soil microbes of different types of forests in three different climatic zones along the north-south transect in eastern China (NSTEC). Both climate and forest type had significant effects on soil enzyme activities and microbial communities with considerable interactive effects. Except for soil acid phosphatase (AP), the other three enzyme activities were much higher in the warm temperate zone than in the temperate and the subtropical climate zones. The soil total PLFAs and bacteria were much higher in the temperate zone than in the warm temperate and the subtropical zones. The soil β-glucosidase (BG) and N-acetylglucosaminidase (NAG) activities were highest in the coniferous forest. Except for the soil fungi and fungi-bacteria (F/B), the different groups of microbial PLFAs were much higher in the conifer broad-leaved mixed forests than in the coniferous forests and the broad-leaved forests. In general, soil enzyme activities and microbial PLFAs were higher in primary forests than in secondary forests in temperate and warm temperate regions. In the subtropical region, soil enzyme activities were lower in the primary forests than in the secondary forests and microbial PLFAs did not differ significantly between primary and secondary forests. Different compositions of the tree species may cause variations in soil microbial communities and enzyme activities. Our results

  8. Soil development as limiting factor for shrub expansion in southwestern Greenland

    Science.gov (United States)

    Caviezel, Chatrina; Hunziker, Matthias; Zoller, Oliver; Wüthrich, Christoph; Kuhn, Nikolaus J.

    2014-05-01

    Southern Greenland currently experiences an increase in summer temperatures and a prolonged growing season (Masson-Delmotte et al. 2012), resulting in an increased shrub cover at the boreal - tundra border ecotone (Normand et al. 2013). These findings suggest the beginning of a greener Greenland in which tundra vegetation is transformed to a boreal woody flora. However, vegetation at borderline ecotones is influenced by further ecologic factors than just temperature. In this study, the ecologic conditions at a selection of sites along an elevation gradient near Igaliku in southern Greenland were examined to identify potential factors limiting the expansion of woody vegetation apart from temperature. The sites differ in elevation, topography, shrub density and soil parent material. The three study sites comprise i) well established birch shrubs growing between 50 and 180 m a.s.l., where the parent material origins from the Julianehab granite (Brooks 2012); ii) extended shrub patches at about 250 m a.s.l., where the parent material consists of Gardar Sandstones and Lavas (Brooks 2012) and iii) restricted shrub patches at an elevation of 250 m a.s.l., where the soil parent material originates from the Gardar intrusions (Brooks 2012). The extent of the shrub areas, topography and soil moisture were mapped, additionally soil samples were analyzed for C-and N-content, texture including coarse fraction and pH and used as soil development indicators. Our results show that the topographic setting regulates the existence or absence of soil while the soil parent material is an important limiting factor for soil moisture. According to these findings, we suggest that a high proportion of areas where temperature increase would allow the increase of shrub cover is not suitable for a woody flora. Brooks, Kent. 2012. "A Tale of Two Intrusions—where Familiar Rock Names No Longer Suffice." Geology Today 28 (1): 13-19. doi:10.1111/j.1365-2451.2012.00815.x. Masson-Delmotte, V., D

  9. Evaluation of Limiting Climatic Factors and Simulation of a Climatically Suitable Habitat for Chinese Sea Buckthorn

    Science.gov (United States)

    Li, Guoqing; Du, Sheng; Guo, Ke

    2015-01-01

    Chinese sea buckthorn (Hippophae rhamnoides subsp. sinensis) has considerable economic potential and plays an important role in reclamation and soil and water conservation. For scientific cultivation of this species across China, we identified the key climatic factors and explored climatically suitable habitat in order to maximize survival of Chinese sea buckthorn using MaxEnt and GIS tools, based on 98 occurrence records from herbarium and publications and 13 climatic factors from Bioclim, Holdridge life zone and Kria' index variables. Our simulation showed that the MaxEnt model performance was significantly better than random, with an average test AUC value of 0.93 with 10-fold cross validation. A jackknife test and the regularized gain change, which were applied to the training algorithm, showed that precipitation of the driest month (PDM), annual precipitation (AP), coldness index (CI) and annual range of temperature (ART) were the most influential climatic factors in limiting the distribution of Chinese sea buckthorn, which explained 70.1% of the variation. The predicted map showed that the core of climatically suitable habitat was distributed from the southwest to northwest of Gansu, Ningxia, Shaanxi and Shanxi provinces, where the most influential climate variables were PDM of 1.0–7.0 mm, AP of 344.0–1089.0 mm, CI of -47.7–0.0°C, and ART of 26.1–45.0°C. We conclude that the distribution patterns of Chinese sea buckthorn are related to the northwest winter monsoon, the southwest summer monsoon and the southeast summer monsoon systems in China. PMID:26177033

  10. Prognostic factors for limited-stage small cell lung cancer: a study of 284 patients.

    Science.gov (United States)

    Chen, Jun; Jiang, Ruoxiang; Garces, Yolanda I; Jatoi, Aminah; Stoddard, Shawn M; Sun, Zhifu; Marks, Randolph S; Liu, Yunpeng; Yang, Ping

    2010-02-01

    Combined modality therapy is the standard care for limited stage-small cell lung cancer (LS-SCLC) and has led to a significant improvement in patients' survival. This study sought to investigate and define the importance of prognostic effects of known and controversial factors especially the impact of smoking status and treatment strategies. A total of 284 patients with LS-SCLC were diagnosed and prospectively followed from 1997 to 2008 at Mayo Clinic; their characteristics and survival outcome were assessed on the basis of age, gender, smoking history, performance status (PS), tumor recurrence or progression, and treatment using Cox proportional hazards models. Our main results are as follows: (1) Although neither smoking status (former or current smokers) nor intensity (pack-years smoked) at the time of SCLC diagnosis were significant survival predictors, compared to continued smokers (who never quit smoking), patients who quit at or after diagnosis cut the risk of death by 45% (HR=0.55, 95% CI 0.38-0.79); patients who quit before lung cancer diagnosis also experienced survival benefit (HR=0.72, 95% CI 0.52-1.00). (2) Thoracic radiotherapy and platinum-based chemotherapy could significantly improve survival but the timing (within or after one month of diagnosis) of starting chemotherapy or radiation therapy did not. (3) After adjusting for other known factors, a lower PS did not predict poorer survival, suggesting that PS should not be the only factor for making treatment decisions. In conclusion, this study demonstrated the negative impact of continued cigarette smoking on survival; therefore, clinicians and all care providers should strongly encourage smoking cessation at diagnosis of LS-SCLC. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  11. Evaluation of Limiting Climatic Factors and Simulation of a Climatically Suitable Habitat for Chinese Sea Buckthorn.

    Directory of Open Access Journals (Sweden)

    Guoqing Li

    Full Text Available Chinese sea buckthorn (Hippophae rhamnoides subsp. sinensis has considerable economic potential and plays an important role in reclamation and soil and water conservation. For scientific cultivation of this species across China, we identified the key climatic factors and explored climatically suitable habitat in order to maximize survival of Chinese sea buckthorn using MaxEnt and GIS tools, based on 98 occurrence records from herbarium and publications and 13 climatic factors from Bioclim, Holdridge life zone and Kria' index variables. Our simulation showed that the MaxEnt model performance was significantly better than random, with an average test AUC value of 0.93 with 10-fold cross validation. A jackknife test and the regularized gain change, which were applied to the training algorithm, showed that precipitation of the driest month (PDM, annual precipitation (AP, coldness index (CI and annual range of temperature (ART were the most influential climatic factors in limiting the distribution of Chinese sea buckthorn, which explained 70.1% of the variation. The predicted map showed that the core of climatically suitable habitat was distributed from the southwest to northwest of Gansu, Ningxia, Shaanxi and Shanxi provinces, where the most influential climate variables were PDM of 1.0-7.0 mm, AP of 344.0-1089.0 mm, CI of -47.7-0.0°C, and ART of 26.1-45.0°C. We conclude that the distribution patterns of Chinese sea buckthorn are related to the northwest winter monsoon, the southwest summer monsoon and the southeast summer monsoon systems in China.

  12. Limiting Factors for Agricultural Production and Differentiation of Soil Management in Romania

    Science.gov (United States)

    Ioana Moraru, Paula; Rusu, Teodor; Bogdan, Ileana; Ioan Pop, Adrian; Pop, Horia

    2017-04-01

    Romania's land area is 23,839,100 ha; 0.16% of the world's surface. Worldwide, Romania is ranked #83 for areal extent, and it consitutes 4.81% of the Europe's surface (ranked #12). Romania has 14,856,800 ha of agricultural land which represents 62.3% of the total surface; 0.65 ha per capita. At the national level, 72.5% and 27.5% of soils in Romania can be broadly classed as very poor and good/very good, respectively, based on intrinsic soil characteristics, climate, topography, and ground water. Romania has a specific geographical situation, namely: i) Romanian territory is located in the southeast portion of Central Europe at the cross roads of several high and low pressure centers that form regularly at the borders. The influence of these air masses is altered by the presence in the central regions of the Carpathian mountain chain resulting in a diverse climate with average annual rain fall amounts between 350 to 1,400 mm and average annual temperatures between 2 and 11.5°C. ii) At the national level, almost all soils in the international classification system are present in Romania; each soil type having specific properties and characteristics. iii) On approximately 12.5 million ha (7.5 million ha arable), soil fertility is adversely affected by erosion, acidity, low humus content, extreme texture (clay, sand), excessive moisture, chemical pollution etc. These natural and anthropogenic factors dramatically influence agricultural production. Furthermore, soil, climate, topography, etc. vary widely not only across the country, but also on smaller scales, even across fields within the same farm. In Steppe zone limitative climatic factors, which require differentiation towards soil management use, include: long periods of drought, high temperatures, high frequency winds (wind erosion in area of sands), low relative air humidity, and harsh frosts during winter. Negative phenomena most commonly encountered in this area are salinization, excess water, temporary

  13. Strategies for conservation of endangered ecosystems

    International Nuclear Information System (INIS)

    Ashraf, M.; Hussain, M.; Ahmad, M.S.A.

    2012-01-01

    The planet Earth is known to host a rich biodiversity owing to its suitable environmental conditions for life and at a larger scale it is regarded as a major ecosystem. Healthy existence of living organisms in this ecosystem depends on proper functioning of all the associated environmental factors. Since millennia, living organisms have adapted to thrive under a limited range of environmental conditions. Nevertheless previous history of the earth and fossil records indicates that the biodiversity housed by the planet earth has experienced five major catastrophic extinctions due to change in physical environment. Even currently, it is undergoing sixth major extinction event mainly due to anthropogenic activities. The human activities are proving a dual menace for biodiversity. On the one hand, it is causing habitat loss through intensive deforestation, conversion of different natural plant communities for agriculture, and urbanization and industrialization. Moreover, it is resulting in habitat degradation by polluting both terrestrial and aquatic ecosystems, emitting air pollutants resulting in acid rains, ozone layer depletion, global warming, heavy metal contamination and eutrophication of water bodies. As a result, healthy existence of both terrestrial and aquatic ecosystems and their associated biodiversity is altogether threatened. Worldwide efforts are underway to conserve the threatened ecosystems and their related biodiversity. A number of international conventions have been held to conserve natural ecosystems. Pakistan being a signatory of these conventions has its obligation to join hands with international community to conserve the endangered ecosystems within as well as outside its bounds. Under the existing scenario the objective of organizing this symposium was to pinpoint the threats to endangered ecosystems of the world in general and those in Pakistan in particular, and to develop suitable strategies for conservation of such paralyzed ecosystems

  14. Integration of a Tick-Borne Encephalitis Virus and Borrelia burgdorferi sensu lato into Mountain Ecosystems, Following a Shift in the Altitudinal Limit of Distribution of Their Vector, Ixodes ricinus (Krkonoše Mountains, Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Danielová, V.; Daniel, M.; Schwarzová, L.; Materna, J.; Rudenko, Natalia; Golovchenko, Maryna; Holubová, J.; Grubhoffer, Libor; Kilian, P.

    2010-01-01

    Roč. 10, č. 3 (2010), s. 223-230 ISSN 1530-3667 Grant - others:GA ČR(CZ) GA310/06/1546 Institutional research plan: CEZ:AV0Z60220518 Keywords : Borrelia burgdorferi genospecies * Climate * Ixodes ricinus tick * Mountain ecosystems * Tick-borne encephalitis virus Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 2.733, year: 2010

  15. How do climatic and management factors affect agricultural ecosystem services? A case study in the agro-pastoral transitional zone of northern China.

    Science.gov (United States)

    Qiao, Jianmin; Yu, Deyong; Wu, Jianguo

    2018-02-01

    Agricultural ecosystem management needs to ensure food production and minimize soil erosion and nitrogen (N) leaching under climate change and increasingly intensive human activity. Thus, the mechanisms through which climatic and management factors affect crop production, soil erosion, and N leaching must be understood in order to ensure food security and sustainable agricultural development. In this study, we adopted the GIS-based Environmental Policy Integrated Climate (EPIC) model to simulate crop production, soil erosion, and N leaching, and used a partial least squares regression model to evaluate the contributions of climate variables (solar radiation, precipitation, wind speed, relative humidity, and maximum and minimum temperature) and management factors (irrigation, fertilization, and crop cultivation area) on agricultural ecosystem services (AES) in the agro-pastoral transitional zone (APTZ) of northern China. The results indicated that crop production and N leaching markedly increased, whereas soil erosion declined from 1980 to 2010 in the APTZ. Management factors had larger effects on the AES than climate change. Among the climatic variables, daily minimum temperature was the most important contributor to the variations in ecosystem services of wheat, maize, and rice. Spatial changes in the cultivated area most affected crop production, soil erosion, and N leaching for majority of the cultivated areas of the three crops, except for the wheat-cultivated area, where the dominant factor for N leaching was fertilization. Although a tradeoff existed between crop production and negative environmental effects, compromises were possible. These findings provide new insights into the effects of climatic and management factors on AES, and have practical implications for improving crop production while minimizing negative environmental impacts. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Age is not a limiting factor for radical radiotherapy in pelvic malignancies

    International Nuclear Information System (INIS)

    Pignon, T.; Horiot, J.C.; Bolla, M.; Poppel, H. van; Bartelink, H.; Roelofsen, F.; Pene, F.; Gerard, A.; Einhorn, N.; Nguyen, T.D.; Vanglabbeke, M.; Scalliet, P.

    1997-01-01

    Background and purpose: Pelvic radiotherapy (RT) toxicity in the elderly is poorly documented. We developed a study aiming to evaluate whether or not a limit of age could be identified beyond which toxicities in patients receiving pelvic RT were more frequent or more severe. Material and methods: 1619 patients with pelvic cancers enrolled in nine EORTC trials, RT arms, were retrospectively studied. Patients were split into six age ranges from 50 years to 70 years and over. Survivals and late toxicity occurrence were calculated with the Kaplan-Meier method and comparison between age groups with the logrank test. A trend test was done to examine if chronological age had an impact on acute toxicity occurrence. Results: Survival was comparable in each age group for prostate (P=0.18), uterus (0.41), anal canal cancer (P=0.6) and slightly better for the younger group of rectum cancer (P=0.04). A total of 1722 acute and 514 late grade ≥1 were recorded. Acute nausea/vomiting, skin complications and performance status deterioration were significantly more frequent in younger patients. There was no trend toward more aged patients to experience diarrhea (P=0.149) and after adjustment on RT dose, acute urinary complications were observed equally in each age range (P=0.32). Eighty percent of patients were free of late complication at 5 years in each age range (P=0.79). For the grade >2 late side-effects, a plateau was observed after 1 year at near 9% without any difference (P=0.06) nor trend (P=0.13) between age-groups. Conclusion: Age per se is not a limiting factor for radical radiotherapy in pelvic malignancies

  17. Scratching the surface: Exploratory analysis of key opinion leaders on rate limiting factors in novel adjuvanted-vaccine

    NARCIS (Netherlands)

    Pronker, E.S.; Claassen, E.; Weenen, T; Commandeur, H; Osterhaus, A.D.M.E.

    2015-01-01

    This exploratory qualitative article analyzes the potentially rate-limiting factors affecting value chain dynamics during adjuvanted-vaccine development. Adjuvants are considered immunostimulating substances that can be added to a vaccine. Although adjuvants have the potential to elicit adverse

  18. Anatomy of a bottleneck: diagnosing factors limiting population growth in the Puerto Rican parrot

    Science.gov (United States)

    Beissenger, S.R.; Wunderle, J.M.; Meyers, J.M.; Saether, B.-E.; Engen, S.

    2008-01-01

    captive young into wild nests), diminishing the importance of nest failure as a limiting factor. Annual survival has been periodically reduced by catastrophes (hurricanes), which have greatly constrained population growth, but survival rates were high under non-catastrophic conditions. Although the importance of factors maintaining the Puerto Rican Parrot bottleneck varied throughout the 30-year period of study, we determined their long-term influence using LSA simulations to correlate variation in demographic rates with variation in population growth (k). The bottleneck appears to have been maintained primarily by periodic catastrophes (hurricanes) that reduced adult survival, and secondarily by environmental and/or behavioral factors that resulted in a failure of many adults to nest. The influence of inbreeding through reduced hatching success played a much less significant role, even when additional effects of inbreeding on the production and mortality of young were incorporated into the LSA. Management actions needed to speed recovery include (1) continued nest guarding to minimize the effects of nest failure due to nongenetic causes; (2) creating a second population at another location on the island --a process that was recently initiated--to reduce the chance that hurricane strikes will cause extinction; and (3) determining the causes of the low percentage of breeders in the population and ameliorating them, which would have a large impact on population growth.

  19. Interministerial decree of 10 February 1988 fixing the derived limits of the air concentration and the annual intake limit and the values of the quality factor and the neutron fluence rate

    International Nuclear Information System (INIS)

    1988-01-01

    This decree establishes the derived concentration limits in the air and annual inhalation limits for the radioisotopes and the values of the quality factors and the conversion factors fluence/dose equivalent for neutrons and protons

  20. Governance of ecosystem services on small islands

    NARCIS (Netherlands)

    Polman, Nico; Reinhard, Stijn; Bets, van L.K.J.; Kuhlman, Tom

    2016-01-01

    Natural ecosystems provide an attractive focus for tourism on small islands. However, at the same time tourism and other human actions can be detrimental to these ecosystems especially because governance of the ecosystem may be difficult due to the limited resilience of small island ecosystems.

  1. Trends and factors limiting pulses-cultivation in the rice-growing areas of pakistan's punjab

    International Nuclear Information System (INIS)

    Anwar, M.Z.; Niazi, M.A.; Niazi, A.; Masood, A.; Malik, R.

    2005-01-01

    Pulses cultivation has an important position both in agricultural activities and in the dietary pattern of the country. So, to meet the domestic needs, pulses are grown in different parts of the Punjab. Previous farm-level studies have shown that pulses were traditionally grown in the rice-producing districts of the province but, presently, farmers had discontinued their cultivation. Consequently, area under pulses rapidly decreased during the past two decades. This study was designed to study the trend and identify the factors limiting pulses cultivation in the region. For this study, both secondary and primary level data were collected. Farm-level information was collected by applying a questionnaire and around 150 farmers were interviewed. Survey results show that only 11.1% farmers were cultivating pulses, while 75.2% and 13.7% were found as dis-adopters and non-adopters. The existing trend of pulses cultivation clearly indicated that until and unless incentives are not given to the pulses growers, reintroduction of pulses in the rice-wheat system is very difficult. (author)

  2. Theory of factors limiting high gradient operation of warm accelerating structures

    Energy Technology Data Exchange (ETDEWEB)

    Nusinovich, Gregory S. [University of Maryland; Antonsen, Thomas M. [University of Maryland; Kishek, Rami [University of Maryland

    2014-07-25

    This final report summarizes the research performed during the time period from 8/1/2010 to 7/31/2013. It consists of two parts describing our studies in two directions: (a) analysis of factors limiting operation of dielectric-loaded accelerating (DLA) structures where the main problem is the occurrence of multipactor on dielectric surfaces, and (b) studies of effects associated with either RF magnetic or RF electric fields which may cause the RF breakdown in high-gradient metallic accelerating structures. In the studies of DLA structures, at least, two accomplishments should be mentioned: the development of a 3D non-stationary, self-consistent code describing the multipactor phenomena and yielding very good agreement with some experimental data obtained in joint ANL/NRL experiments. In the metallic structures, such phenomena as the heating and melting of micro-particles (metallic dust) by RF electric and magnetic fields in single-shot and rep-rate regimes is analyzed. Also, such processes in micro-protrusions on the structure surfaces as heating and melting due to the field emitted current and the Nottingham effect are thoroughly investigated with the account for space charge of emitted current on the field emission from the tip.

  3. Real-time PCR for quantifying Haemonchus contortus eggs and potential limiting factors.

    Science.gov (United States)

    Harmon, Aaron F; Williams, Zachary B; Zarlenga, Dante S; Hildreth, Michael B

    2007-06-01

    The purpose of this study was to evaluate the practicality of using real-time PCR for quantifying feces-derived trichostrongyle eggs. Haemonchus contortus eggs were used to evaluate fecal contaminants, time after egg embryonation, and the presence of competing and non-competing DNAs as factors that might interfere with generating reproducible results during simplex and multiplex quantitative real-time PCR (QPCR). Real-time PCR results showed linear quantifiable amplification with DNA from five to 75 eggs. However, threshold cycle (C (T)) values obtained by amplification of DNA from egg numbers between 75 and 1,000 did not differ significantly. Inhibitors of QPCR were effectively removed during DNA extraction as exemplified by the absence of any improvement in C (T) values with bovine serum albumin or phytase treatments. Changes from egg embryonation could only be detected during the first 6 h. Noncompetitive DNA did not appear to impact amplification; however, in a multiplex reaction a competing trichostrongyle such as Cooperia oncophora can hinder amplification of H. contortus DNA, when present at tenfold greater amounts. This study demonstrates the usefulness of QPCR for amplification and quantification of trichostrongyle eggs, and identifies potential limitations, which may be addressed through multiplex assays or the addition of a standard: exogenous DNA target.

  4. Embracing the emerging precision agriculture technologies for site-specific management of yield-limiting factors.

    Science.gov (United States)

    Melakeberhan, H

    2002-09-01

    Precision agriculture (PA) is providing an information revolution using Global Positioning (GPS) and Geographic Information (GIS) systems and Remote Sensing (RS). These technologies allow better decision making in the management of crop yield-limiting biotic and abiotic factors and their interactions on a site-specific (SSM) basis in a wide range of production systems. Characterizing the nature of the problem(s) and public education are among the challenges that scientists, producers, and industry face when adapting PA technologies. To apply SSM, spatio-temporal characteristics of the problem(s) need to be determined and variations within a field demonstrated. Spatio-temporal characteristics of a given pathogen or pest problem may be known but may not be the only or primary cause of the problem. Hence, exact cause-and-effect relationships need to be established by incorporating GIS, GPS, and RS-generated data as well as possible interactions. Exploiting the potential of PA technologies in sustainable ways depends on whether or not we first ask ''Are we doing the right thing?'' (strategic) as opposed to ''Are we doing it right?'' (tactical).

  5. Transport and homeostasis of potassium and phosphate: limiting factors for sustainable crop production.

    Science.gov (United States)

    Luan, Mingda; Tang, Ren-Jie; Tang, Yumei; Tian, Wang; Hou, Congong; Zhao, Fugeng; Lan, Wenzhi; Luan, Sheng

    2017-06-01

    Potassium (K) and phosphate (Pi) are both macronutrients essential for plant growth and crop production, but the unrenewable resources of phosphorus rock and potash have become limiting factors for food security. One critical measure to help solve this problem is to improve nutrient use efficiency (NUE) in plants by understanding and engineering genetic networks for ion uptake, translocation, and storage. Plants have evolved multiple systems to adapt to various nutrient conditions for growth and production. Within the NUE networks, transport proteins and their regulators are the primary players for maintaining nutrient homeostasis and could be utilized to engineer high NUE traits in crop plants. A large number of publications have detailed K+ and Pi transport proteins in plants over the past three decades. Meanwhile, the discovery and validation of their regulatory mechanisms are fast-track topics for research. Here, we provide an overview of K+ and Pi transport proteins and their regulatory mechanisms, which participate in the uptake, translocation, storage, and recycling of these nutrients in plants. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  6. Updating Environmental Media Concentration Limits and Uncertainty factors in the ERICA Tool

    Energy Technology Data Exchange (ETDEWEB)

    Brown, J.E.; Hosseini, A. [Norwegian Radiation Protection Authority, P.O. Box 55, N-1332 Oesteraas (Norway); Alfonso, B.; Avila, R. [Facilia AB, S-167 51 Bromma (Sweden); Beresford, N.A. [Centre for Ecology and Hydrology, CEH-Lancaster, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA 1 4AP (United Kingdom); Copplestone, D. [Dept. Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA (United Kingdom)

    2014-07-01

    Tiered approaches have become a standard means of structuring information in the process of conducting environmental risk assessments. For cases involving the assessment of impacts on wildlife from ionising radiation, the ERICA integrated approach and its supporting software (The ERICA Tool) provides such a structure, splitting the system into two generic screening tiers and a third site-specific tier. The first Tier is very simple, based around Environmental Media Concentration Limits, EMCLs, and requires minimal input from the assessor. The second Tier, although still a screening tier, calculates dose rates and requires more detailed input from the assessor allowing for scrutiny and editing of default parameters in the process. A key element of Tier 2 involves the application of Uncertainty Factors, UFs. Such factors reflect our knowledge concerning probability distribution functions and provide a way of incorporating conservatism into the assessment by considering high percentile values in underlying parameters. Following its launch in 2007, there have been significant developments regarding certain components of the ERICA integrated approach. Most notably, an extended international collation of concentration ratio data has precipitated the need to update parameter values in the Tools databases. In addition, more considered guidance has been developed with regards to filling knowledge gaps in the absence of transfer data. Furthermore, the efficacy of the methods used in assigning probability distribution functions has been questioned leading to an acknowledgement from the developers that the methods were not described in enough detail nor were the justifications for applying the selected approach provided in a convincing way. This has implications for the EMCL values which are derived probabilistically using parameters including concentration ratios. Furthermore, there are implications for UF derivation that relies upon a robust consideration of underlying

  7. Pesticide Pollution in Ecosystems

    OpenAIRE

    İlter, Hüseyin; Kurt, Burak; Ötegen, Volkan Recai; Akbaba, Muhsin

    2018-01-01

    Pesticidepollution affects both aquatic and soil ecosystems. Factors that promotepesticide pollution include drainage patterns, properties of the pesticide,rainfall, microbial activity, treatment surface and rate of application.Pesticides are able to move from one ecosystem to another through processessuch as transfer (mobility) and transformation (degradation). Transfer mayoccur through surface runoff, vapourization to atmosphere, sorption (adsorp‐tion/desorp-tion), plant uptakeor soil water...

  8. Phycoremediation of landfill leachate with chlorophytes: Phosphate a limiting factor on ammonia nitrogen removal.

    Science.gov (United States)

    Paskuliakova, Andrea; Tonry, Steven; Touzet, Nicolas

    2016-08-01

    The potential of microalgae to bioremediate wastewater has been reported in numerous studies but has not been investigated as extensively for landfill leachate, which may be attributed to its complex nature and toxicity. In this study we explored if microalgal phycoremediation could constitute an alternative biological treatment option for landfill leachate management in regions with temperate climatic conditions. The aim of this study was to assess the performance of microalgae species at relatively low temperature (15 °C) and light intensity (14:10 h, light: dark, 22 μmol m(-2) s(-1)) for reduction in energy inputs. Four chlorophyte strains originating from the North-West of Ireland were selected and used in batch experiments in order to evaluate their ability to reduce total ammonia nitrogen, oxidised nitrogen and orthophosphate in landfill leachate. The Chlamydomonas sp. strain SW15aRL isolated from raw leachate achieved the highest level of pollutant reduction whereby a decrease of 51.7% of ammonia nitrogen was observed in 10% raw leachate (∼100 mg l(-1) NH4(+)-N) by day 24 in experiments without culture agitation. However, in the experiment conducted with 10% raw leachate supplemented with phosphate, a decrease of 90.7% of ammonia nitrogen was obtained by day 24 while also achieving higher biomass production. This series of experiments pointed to phosphorus being a limiting factor in the microalgae based phycoremediation of the landfill leachate. The effective reduction of ammonia nitrogen in landfill leachate can be achieved at lower temperature and light conditions. This was attained by employing native species adapted to such conditions and by improving nutrient balance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Factors associated with use of slip-resistant shoes in US limited-service restaurant workers.

    Science.gov (United States)

    Verma, Santosh K; Courtney, Theodore K; Corns, Helen L; Huang, Yueng-Hsiang; Lombardi, David A; Chang, Wen-Ruey; Brennan, Melanye J; Perry, Melissa J

    2012-06-01

    Slips and falls are a leading cause of injury at work. Several studies have indicated that slip-resistant shoes can reduce the risk of occupational slips and falls. Few studies, however, have examined the determinants of slip-resistant shoe use. This study examined the individual and workplace factors associated with slip-resistant shoe use. 475 workers from 36 limited-service restaurants in the USA participated in a study of workplace slipping. Demographic and job characteristic information about each participant was collected. Restaurant managers provided information on whether slip-resistant shoes were provided and paid for by the employer and whether any guidance was given regarding slip-resistant shoe use when they were not provided. Kitchen floor coefficient of friction was measured. Slip-resistant status of the shoes was determined by noting the presence of a 'slip-resistant' marking on the sole. Poisson regression with robust SE was used to calculate prevalence ratios. 320 participants wore slip-resistant shoes (67%). In the multivariate analysis, the prevalence of slip-resistant shoe use was lowest in 15-19-year age group. Women were more likely to wear slip-resistant shoes (prevalence ratio 1.18, 95% CI 1.07 to 1.31). The prevalence of slip-resistant shoe use was lower when no guidance regarding slip-resistant shoes was given as compared to when they were provided by the employer (prevalence ratio 0.66, 95% CI 0.55 to 0.79). Education level, job tenure and the mean coefficient of friction had no significant effects on the use of slip-resistant shoes. Provision of slip-resistant shoes was the strongest predictor of their use. Given their effectiveness and low cost, employers should consider providing slip-resistant shoes at work.

  10. Is oxygen supply a limiting factor for survival during rewarming from profound hypothermia?

    Science.gov (United States)

    Kondratiev, Timofei V; Flemming, Kristina; Myhre, Eivind S P; Sovershaev, Mikhail A; Tveita, Torkjel

    2006-07-01

    It has been postulated that unsuccessful resuscitation of victims of accidental hypothermia is caused by insufficient tissue oxygenation. The aim of this study was to test whether inadequate O2 supply and/or malfunctioning O2 extraction occur during rewarming from deep/profound hypothermia of different duration. Three groups of rats (n = 7 each) were used: group 1 served as normothermic control for 5 h; groups 2 and 3 were core cooled to 15 degrees C, kept at 15 degrees C for 1 and 5 h, respectively, and then rewarmed. In both hypothermic groups, cardiac output (CO) decreased spontaneously by > 50% in response to cooling. O2 consumption fell to less than one-third during cooling but recovered completely in both groups during rewarming. During hypothermia, circulating blood volume in both groups was reduced to approximately one-third of baseline, indicating that some vascular beds were critically perfused during hypothermia. CO recovered completely in animals rewarmed after 1 h (group 2) but recovered to only 60% in those rewarmed after 5 h (group 3), whereas blood volume increased to approximately three-fourths of baseline in both groups. Metabolic acidosis was observed only after 5 h of hypothermia (15 degrees C). A significant increase in myocardial tissue heat shock protein 70 after rewarming in group 3, but not in group 2, indicates an association with the duration of hypothermia. Thus mechanisms facilitating O2 extraction function well during deep/profound hypothermia, and, despite low CO, O2 supply was not a limiting factor for survival in the present experiments.

  11. Weathering as the limiting factor of denudation in the Western escarpment of the Andes

    Science.gov (United States)

    Abbühl, L. M.; Schlunegger, F.; Kracht, O.; Ramseyer, K.; Rieke-Zapp, D.; Aldahan, A.; von Blanckenburg, F.

    2009-04-01

    additional river profile knickzone in the transition zone between the easterlies and the westerlies. Analysis of 10Be in quartz of river-born sand and of bedrock reveals that denudation correlates positively with the present-day rainfall pattern related to the easterlies. Denudation rates in the headwaters range from 0.14 mm/year in Northern Peru down to 0.05 mm/yr in Northern Chile (Kober et al., 2007). In addition, 10Be-based denudation rates reveal a decreasing trend from the Cordillera to the Pacific coast that positively correlates with the decreasing precipitation rate, irrespective of the nature of the bedrock. Interestingly, the 10Be analysis conducted in the Piura system reveals no influence of the episodic precipitation in relation to El Niño on the sediment production rates. In summary, the pattern of denudation rates together with morphometric observations and quantitative denudation rate estimates strongly hints at weathering being the driving but also limiting factor of denudation. Accordingly, in the western Peruvian Andes, sediment production and export are most probably controlled by the pattern and rate of precipitation. Kober, F., Ivy-Ochs, S., Schlunegger, F., Baur, H., Kubik, P. W., and Wieler, R. (2007). Denudation rates and a topography-driven rainfall threshold in northern Chile: Multiple cosmogenic nuclide data and sediment yield budgets. Geomorphology 83, 97-120.

  12. AQUATIC ECOSYSTEMS,

    Science.gov (United States)

    Aquatic ecosystems are a vital part of the urban water cycle (and of urban areas more broadly), and, if healthy, provide a range of goods and services valued by humans (Meyer 1997). For example, aquatic ecosystems (e.g., rivers, lakes, wetlands) provide potable water, food resou...

  13. High-resolution chemical and hydrologic records identify environmental factors that control coastal anchialine cave ecosystem function

    Science.gov (United States)

    Brankovits, D.; Pohlman, J.; Lapham, L.; Casso, M.; Roth, E.; Lowell, N. S.; Iliffe, T. M.

    2015-12-01

    Anchialine caves host a coastal aquifer ecosystem occupied by cave-adapted crustaceans that reside within distinct fresh, brackish and marine waters. Our initial investigation of this subsurface ecotone in the Yucatan Peninsula (Mexico) provides stable isotope-based evidence that methane and dissolved organic carbon (DOC) are the primary sources of energy and carbon for the food web. However, the frequency of observations is sparse, leaving us 'in the dark' with respect to the temporal dynamics of the ecosystem function. In this study, we obtained undisturbed vertical profiles of methane, DOC and DIC concentration and isotopic composition with the 'Octopipi' water sampler from an anchialine cave located ~8 km from the coastline. To document the temporal variability of methane availability in the cave, we deployed an osmotically-driven pump (OsmoSampler). Data loggers recorded dissolved oxygen (DO), salinity, temperature and current velocities, and a rain gauge recorded precipitation. A high-methane water mass near the ceiling (up to 7795 nM) contained elevated concentration (900 µM), 13C-depleted (-27.8 to -28.2 ‰) DOC, suggesting terrestrial organic matter input from the overlying soils. Low-methane saline water (36 to 84 nM) had lower concentration DOC (15 to 97 µM) with a similar δ13C (-25.9 to -27.2 ‰), suggesting significant terrestrial organic matter consumption or removal with increasing depth, from fresh to saline water, within the water column. Our 6-month water chemistry record reveals high concentrations of methane in the wet season, especially following rainfall events, and relatively lower methane concentrations in the dry season. These observations suggest rain flushes methane generated in overlying anoxic soils into the cave. DO, water level, and groundwater flow patterns were also linked to the precipitation record. These data provide novel insight into the interconnections between external climate forcing and subterranean anchialine

  14. Affecting Factors and Recent Improvements of the Photochemical Reflectance Index (PRI for Remotely Sensing Foliar, Canopy and Ecosystemic Radiation-Use Efficiencies

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2016-08-01

    Full Text Available Accurately assessing terrestrial gross primary productivity (GPP is crucial for characterizing the climate-carbon cycle. Remotely sensing the photochemical reflectance index (PRI across vegetation functional types and spatiotemporal scales has received increasing attention for monitoring photosynthetic performance and simulating GPP over the last two decades. The factors confounding PRI variation, especially on long timescales, however, require the improvement of PRI understanding to generalize its use for estimating carbon uptake. In this review, we summarize the most recent publications that have reported the factors affecting PRI variation across diurnal and seasonal scales at foliar, canopy and ecosystemic levels; synthesize the reported correlations between PRI and ecophysiological variables, particularly with radiation-use efficiency (RUE and net carbon uptake; and analyze the improvements in PRI implementation. Long-term variation of PRI could be attributed to changes in the size of constitutive pigment pools instead of xanthophyll de-epoxidation, which controls the facultative short-term changes in PRI. Structural changes at canopy and ecosystemic levels can also affect PRI variation. Our review of the scientific literature on PRI suggests that PRI is a good proxy of photosynthetic efficiency at different spatial and temporal scales. Correcting PRI by decreasing the influence of physical or physiological factors on PRI greatly strengthens the relationships between PRI and RUE and GPP. Combining PRI with solar-induced fluorescence (SIF and optical indices for green biomass offers additional prospects.

  15. Effects of Water and Nitrogen Addition on Ecosystem Carbon Exchange in a Meadow Steppe

    Science.gov (United States)

    Wang, Yunbo; Jiang, Qi; Yang, Zhiming; Sun, Wei; Wang, Deli

    2015-01-01

    A changing precipitation regime and increasing nitrogen deposition are likely to have profound impacts on arid and semiarid ecosystem C cycling, which is often constrained by the timing and availability of water and nitrogen. However, little is known about the effects of altered precipitation and nitrogen addition on grassland ecosystem C exchange. We conducted a 3-year field experiment to assess the responses of vegetation composition, ecosystem productivity, and ecosystem C exchange to manipulative water and nitrogen addition in a meadow steppe. Nitrogen addition significantly stimulated aboveground biomass and net ecosystem CO2 exchange (NEE), which suggests that nitrogen availability is a primary limiting factor for ecosystem C cycling in the meadow steppe. Water addition had no significant impacts on either ecosystem C exchange or plant biomass, but ecosystem C fluxes showed a strong correlation with early growing season precipitation, rather than whole growing season precipitation, across the 3 experimental years. After we incorporated water addition into the calculation of precipitation regimes, we found that monthly average ecosystem C fluxes correlated more strongly with precipitation frequency than with precipitation amount. These results highlight the importance of precipitation distribution in regulating ecosystem C cycling. Overall, ecosystem C fluxes in the studied ecosystem are highly sensitive to nitrogen deposition, but less sensitive to increased precipitation. PMID:26010888

  16. Contrasting Patterns of Phytoplankton Assemblages in Two Coastal Ecosystems in Relation to Environmental Factors (Corsica, NW Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Marie Garrido

    2014-04-01

    Full Text Available Corsica Island is a sub-basin of the Northwestern Mediterranean Sea, with hydrological features typical of both oligotrophic systems and eutrophic coastal zones. Phytoplankton assemblages in two coastal ecosystems of Corsica (the deep Bay of Calvi and the shallow littoral of Bastia show contrasting patterns over a one-year cycle. In order to determine what drives these variations, seasonal changes in littoral phytoplankton are considered together with environmental parameters. Our methodology combined a survey of the physico-chemical structure of the subsurface water with a characterization of the phytoplankton community structure. Sampling provided a detailed record of the seasonal changes and successions that occur in these two areas. Results showed that the two sampled stations presented different phytoplankton abundance and distribution patterns, notably during the winter–spring bloom period. Successions in pico-, nano-, and microphytoplankton communities appeared mainly driven by differences in the ability to acquire nutrients, and in community-specific growth rates. Phytoplankton structure and dynamics are discussed in relation to available data on the Northwestern Mediterranean Sea. These results confirm that integrated monitoring of coastal areas is a requisite for gaining a proper understanding of marine ecosystems.

  17. Obesity as a risk factor for developing functional limitation among older adults: A conditional inference tree analysis.

    Science.gov (United States)

    Cheng, Feon W; Gao, Xiang; Bao, Le; Mitchell, Diane C; Wood, Craig; Sliwinski, Martin J; Smiciklas-Wright, Helen; Still, Christopher D; Rolston, David D K; Jensen, Gordon L

    2017-07-01

    To examine the risk factors of developing functional decline and make probabilistic predictions by using a tree-based method that allows higher order polynomials and interactions of the risk factors. The conditional inference tree analysis, a data mining approach, was used to construct a risk stratification algorithm for developing functional limitation based on BMI and other potential risk factors for disability in 1,951 older adults without functional limitations at baseline (baseline age 73.1 ± 4.2 y). We also analyzed the data with multivariate stepwise logistic regression and compared the two approaches (e.g., cross-validation). Over a mean of 9.2 ± 1.7 years of follow-up, 221 individuals developed functional limitation. Higher BMI, age, and comorbidity were consistently identified as significant risk factors for functional decline using both methods. Based on these factors, individuals were stratified into four risk groups via the conditional inference tree analysis. Compared to the low-risk group, all other groups had a significantly higher risk of developing functional limitation. The odds ratio comparing two extreme categories was 9.09 (95% confidence interval: 4.68, 17.6). Higher BMI, age, and comorbid disease were consistently identified as significant risk factors for functional decline among older individuals across all approaches and analyses. © 2017 The Obesity Society.

  18. Decomposition Analysis of Forest Ecosystem Services Values

    Directory of Open Access Journals (Sweden)

    Hidemichi Fujii

    2017-04-01

    Full Text Available Forest ecosystem services are fundamental for human life. To protect and increase forest ecosystem services, the driving factors underlying changes in forest ecosystem service values must be determined to properly implement forest resource management planning. This study examines the driving factors that affect changes in forest ecosystem service values by focusing on regional forest characteristics using a dataset of 47 prefectures in Japan for 2000, 2007, and 2012. We applied two approaches: a contingent valuation method for estimating the forest ecosystem service value per area and a decomposition analysis for identifying the main driving factors of changes in the value of forest ecosystem services. The results indicate that the value of forest ecosystem services has increased due to the expansion of forest area from 2000 to 2007. However, factors related to forest management and ecosystem service value per area have contributed to a decrease in the value of ecosystem services from 2000 to 2007 and from 2007 to 2012, respectively.

  19. Ecosystem thermodynamics

    International Nuclear Information System (INIS)

    Gomez Palacio, German Rau

    1998-01-01

    Ecology is no more a descriptive and self-sufficient science. Many viewpoints are needed simultaneously to give a full coverage of such complex systems: ecosystems. These viewpoints come from physics, chemistry, and nuclear physics, without a new far from equilibrium thermodynamics and without new mathematical tools such as catastrophe theory, fractal theory, cybernetics and network theory, the development of ecosystem science would never have reached the point of today. Some ideas are presented about the importance that concept such as energy, entropy, exergy information and none equilibrium have in the analysis of processes taking place in ecosystems

  20. Length-weight relationship and condition factor of white shrimp Penaeus merguiensis captured in ecosystem mangrove of Bagan Asahan, Tanjungbalai, Asahan, North Sumatra, Indonesia

    Science.gov (United States)

    Suryanti, A.; Riza, N.; Raza'i, T. S.

    2018-02-01

    White Shrimp Penaeus merguiensis was commonly found in Mangrove Ecosystem of Bagan Asahan Village. The purpose of this research are to determine length-weight relationship and condition factor of white shrimp Penaeus merguiensis around ecosystem mangrove waters in Bagan Asahan Village. This research was conducted for 3 month in Maret until Mei 2017 with determination of research station used purposive sampling method. The shrimp samples were taken by shrimp trawl. The result showed that 98 shrimp which consists of 58 males and 40 female. The carapace length of female shrimp between 6,05 - 22,125 mm and total weight ranged from 0,12 - 6,95 g. Male shrimp had carapace length between 7.125 - 18.25 mm and total weigth ranged from 0.14 - 3.82 g. Female and male white shrimp had different growth pattern. Female shrimp had b = 2.984 included in negaive allometric and male shrimps with b = 3.187 included in positive allometric. The value of correlation coefficients was more than 90% for both male and female showed very strong relation between length carapace and body weight. The value of shrimp condition factor ranged from 0.570 - 1.773 and included to flat (thin) body shrimp.

  1. Turbulence Considerations for Comparing Ecosystem Exchange over Old-Growth and Clear-Cut Stands For Limited Fetch and Complex Canopy Flow Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wharton, S; Schroeder, M; Paw U, K T; Falk, M; Bible, K

    2009-01-08

    Carbon dioxide, water vapor and energy fluxes were measured using eddy covariance (EC) methodology over three adjacent forests in southern Washington State to identify stand-level age-effects on ecosystem exchange. The sites represent Douglas-fir forest ecosystems at two contrasting successional stages: old-growth (OG) and early seral (ES). Here we present eddy flux and meteorological data from two early seral stands and the Wind River AmeriFlux old-growth forest during the growing season (March-October) in 2006 and 2007. We show an alternative approach to the usual friction velocity (u*) method for determining periods of adequate atmospheric boundary layer (ABL) mixing based on the ratio of mean horizontal ({bar u}) and vertical ({bar w}) wind flow to a modified turbulent kinetic energy scale (uTKE). This new parameter in addition to footprint modeling showed that daytime CO{sub 2} fluxes (F{sub NEE}) in small clear-cuts (< 10 hectares) can be measured accurately with EC if micrometeorological conditions are carefully evaluated. Peak midday CO{sub 2} fluxes (F{sub NEE} = -14.0 to -12.3 {micro}mol m{sup -2} s{sup -1}) at OG were measured in April in both 2006 and 2007 before bud break when air and soil temperatures and vapor pressure deficit were relatively low, and soil moisture and light levels were favorable for photosynthesis. At the early seral stands, peak midday CO{sub 2} fluxes (F{sub NEE} = -11.0 to -8.7 {micro}mol m{sup -2} s{sup -1}) were measured in June and July while spring-time CO{sub 2} fluxes were much smaller (F{sub NEE} = -3.8 to -3.6 {micro}mol m{sup -2} s{sup -1}). Overall, we measured lower evapotranspiration (OG = 230 mm; ES = 297 mm) higher midday F{sub NEE} (OG F{sub NEE} = -9.0 {micro}mol m{sup -2} s{sup -1}; ES F{sub NEE} = -7.3 {micro}mol m{sup -2} s{sup -1}) and higher Bowen ratios (OG {beta} = 2.0. ES {beta} = 1.2) at the old-growth forest than at the ES sites during the summer months (May-August). Eddy covariance studies such as ours

  2. Risky Sexual Behavior among Rural Female Adolescents in Malaysia: A Limited Role of Protective Factors

    OpenAIRE

    Ahmadian, Maryam; Hamsan, Hanina H.; Abdullah, Haslinda; Samah, Asnarulkhadi Abu; Noor, Amna Md

    2014-01-01

    Purpose: This paper presents the findings of a cross-sectional survey on the risk and protective factors of premarital sexual behavior among rural female adolescents in Peninsular Malaysia. Methods: We investigated data on 770 female respondents aged 13-17 years in rural areas to identify predictive factors for premarital sexual intercourse. Data were analyzed using bivariate and multivariate regression. Specific socio-demographic factors, psychological and family domains, peer delinquency, a...

  3. Human Factors Assessment of the UH-60M Crew Station During the Limited User Test (LUT)

    National Research Council Canada - National Science Library

    Havir, Thomas J; Durbin, David B; Frederick, Lorraine J; Hicks, Jamison S

    2006-01-01

    The utility helicopter (UH)-60M Product Manager requested the U.S. Army Research Laboratory's Human Research and Engineering Directorate to participate in the Limited User Test for the UH-60M Black Hawk...

  4. Factors affecting the abundance of wild rabbit (Oryctolagus cuniculus in agro-ecosystems of the Mount Etna Park

    Directory of Open Access Journals (Sweden)

    Susanna Caruso

    2001-09-01

    Full Text Available Abstract A study on the abundance of Wild rabbit Oryctolagus cuniculus and environmental factors which may affect its occurrence in agro-ecosystems of Mount Etna was carried out in 1998. Density data, collected monthly by pellet counts in 7 sample areas, show a mean value of 9.16 individuals per hectare; in two samples high density values were recorded and the difference compared to other areas was significant. Two peaks of abundance were recorded during the year. No significant correlation was found between rabbit density and the factors considered but altitude and percentage of abandoned cultivation seem to have a certain influence on the occurrence of the species. The main natural predators, Vulpes vulpes and Buteo buteo, do not have any negative effect on rabbit abundance.

  5. An analysis of diversity factors applied to harmonic emission limits for energy saving lamps

    NARCIS (Netherlands)

    Cuk, V.; Cobben, J.F.G.; Kling, W.L.; Timens, R.B.

    2010-01-01

    An experimental investigation of diversity factors for CFLs (compact fluorescent lamps) in combination with LED (light emitting diode) lamps is presented in this paper. Diversity factors were calculated for different configurations of lamps connected to the same feeder in one phase. It was found

  6. Endogenous tissue factor pathway inhibitor has a limited effect on host defence in murine pneumococcal pneumonia

    NARCIS (Netherlands)

    van den Boogaard, Florry E.; van 't Veer, Cornelis; Roelofs, Joris J. T. H.; Meijers, Joost C. M.; Schultz, Marcus J.; Broze, George J.; van der Poll, Tom

    2015-01-01

    Streptococcus (S.) pneumoniae is the most common causative pathogen in community-acquired pneumonia. Coagulation and inflammation interact in the host response to infection. Tissue factor pathway inhibitor (TFPI) is a natural anticoagulant protein that inhibits tissue factor (TF), the main activator

  7. Climate factors play a limited role for past adaptation strategies in West Africa

    DEFF Research Database (Denmark)

    Mertz, Ole; Mbow, Cheikh; Nielsen, Jonas Østergaard

    2010-01-01

    The Sudano-Sahelian zone of West Africa has experienced recurrent droughts since the mid-1970s and today there is considerable concern for how this region will be able to adapt to future climate change. To develop well targeted adaptation strategies, the relative importance of climate factors...... as drivers of land use and livelihood change need to be better understood. Based on the perceptions of 1249 households in five countries across an annual rainfall gradient of 400-900 mm, we provide an estimate of the relative weight of climate factors as drivers of changes in rural households during the past...... 20 years. Climate factors, mainly inadequate rainfall, are perceived by 30-50% of households to be a cause of decreasing rainfed crop production, whereas a wide range of other factors explains the remaining 50-70%. Climate factors are much less important for decreasing livestock production...

  8. Changing Arctic ecosystems--research to understand and project changes in marine and terrestrial ecosystems of the Arctic

    Science.gov (United States)

    Geiselman, Joy; DeGange, Anthony R.; Oakley, Karen; Derksen, Dirk; Whalen, Mary

    2012-01-01

    Ecosystems and their wildlife communities are not static; they change and evolve over time due to numerous intrinsic and extrinsic factors. A period of rapid change is occurring in the Arctic for which our current understanding of potential ecosystem and wildlife responses is limited. Changes to the physical environment include warming temperatures, diminishing sea ice, increasing coastal erosion, deteriorating permafrost, and changing water regimes. These changes influence biological communities and the ways in which human communities interact with them. Through the new initiative Changing Arctic Ecosystems (CAE) the U.S. Geological Survey (USGS) strives to (1) understand the potential suite of wildlife population responses to these physical changes to inform key resource management decisions such as those related to the Endangered Species Act, and (2) provide unique insights into how Arctic ecosystems are responding under new stressors. Our studies examine how and why changes in the ice-dominated ecosystems of the Arctic are affecting wildlife and will provide a better foundation for understanding the degree and manner in which wildlife species respond and adapt to rapid environmental change. Changes to Arctic ecosystems will be felt broadly because the Arctic is a production zone for hundreds of species that migrate south for the winter. The CAE initiative includes three major research themes that span Arctic ice-dominated ecosystems and that are structured to identify and understand the linkages between physical processes, ecosystems, and wildlife populations. The USGS is applying knowledge-based modeling structures such as Bayesian Networks to integrate the work.

  9. Attaining higher resolution visual prosthetics: a review of the factors and limitations

    Science.gov (United States)

    Eiber, Calvin D.; Lovell, Nigel H.; Suaning, Gregg J.

    2013-02-01

    Visual prosthetics is an expanding subfield of functional electrical stimulation which has gained increased interest recently in light of new advances in treatments and technology. These treatments and technology represent a major improvement over prior art, but are still subject to a host of limitations which are dependent on the manner in which one approaches the topic of visual prosthetics. These limitations pose new research challenges whose solutions are directly applicable to the well-being of blind individuals everywhere. In this review, we will outline and critically compare major current approaches to visual prosthetics, and in particular retinal prosthetics. Then, we will engage in an in-depth discussion of the limitations imposed by current technology, physics, and the underlying biology of the retina to highlight several of the challenges currently facing researchers. .

  10. An ecosystem approach to determining effects of prescribed fire on southwestern borderlands oak savannas: A baseline study

    Science.gov (United States)

    Gerald J. Gottfried; Daniel G. Neary; Peter F. Ffolliott

    2007-01-01

    Many traditional land management activities and supporting research have concentrated on one or two resources, with limited evaluations of interactions among other potential values. An ecosystem approach to land management requires an evaluation of the blend of physical and biological factors needed to assure productive, healthy ecosystems. Ideally, social and economic...

  11. [Limiting a Medline/PubMed query to the "best" articles using the JCR relative impact factor].

    Science.gov (United States)

    Avillach, P; Kerdelhué, G; Devos, P; Maisonneuve, H; Darmoni, S J

    2014-12-01

    Medline/PubMed is the most frequently used medical bibliographic research database. The aim of this study was to propose a new generic method to limit any Medline/PubMed query based on the relative impact factor and the A & B categories of the SIGAPS score. The entire PubMed corpus was used for the feasibility study, then ten frequent diseases in terms of PubMed indexing and the citations of four Nobel prize winners. The relative impact factor (RIF) was calculated by medical specialty defined in Journal Citation Reports. The two queries, which included all the journals in category A (or A OR B), were added to any Medline/PubMed query as a central point of the feasibility study. Limitation using the SIGAPS category A was larger than the when using the Core Clinical Journals (CCJ): 15.65% of PubMed corpus vs 8.64% for CCJ. The response time of this limit applied to the entire PubMed corpus was less than two seconds. For five diseases out of ten, limiting the citations with the RIF was more effective than with the CCJ. For the four Nobel prize winners, limiting the citations with the RIF was more effective than the CCJ. The feasibility study to apply a new filter based on the relative impact factor on any Medline/PubMed query was positive. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  12. Four-loop photon quark form factor and cusp anomalous dimension in the large-Nc limit of QCD

    International Nuclear Information System (INIS)

    Henn, Johannes; Lee, Roman N.; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias

    2017-01-01

    We compute the four-loop QCD corrections to the massless quark-anti-quark-photon form factor F q in the large-N c limit. From the pole part we extract analytic expressions for the corresponding cusp and collinear anomalous dimensions.

  13. Combining Eddy Covariance, Leaf Level Measurements and Modelling to Investigate Ecosystem Fluxes in Tropical Grasslands

    Science.gov (United States)

    Wohland, P.; Mantlana, B.; Kattge, J.

    2007-12-01

    Our project determined seasonal and spatial variations in ecosystem fluxes of tropical grassland ecosystems by investigating three prominent grassland types along a hydrological gradient in the Okavango Delta, Botswana.To identify the environmental factors that control CO2 and H2O exchange in tropical grassland ecosystems, we successfully combined eddy covariance measurements, leaf level measurements and remotely sensed data.Grassland ecosystems growing under the same climate showed profound differences in ecosystem fluxes as well as what regulated those fluxes on an ecosystem level. The analysis of the eddy covariance measurements revealed a pronounced seasonal and spatial variation with maximum net ecosystem exchange (NE) varying between -25μ mol -2 s-1 and -1μ mol -2 s-1 across sites and seasons. Without water limitation the main factor for the differences in NE between ecosystems was nutrient content per vegetation unit. This importance of nutrient content was also confirmed by our leaf level measurements. Seasonal differences in NE varied between sites and were driven by phenology or temperature and light limitation.Eddy covariance measurements for this project were predominantly campaign measurements. To determine annual course and sum of NE, we adapted the ecosystem model BETHY (Biosphere-Energy Transfer Hydrology Scheme) by parameter inversion in combination with remotely sensed fraction of absorbed photosynthetically active radiation for each site.

  14. Soil physical constraints as a limiting factor of palm and tree basal area in amazonian forests

    NARCIS (Netherlands)

    Emilio, T.; Quesada, C.A.; Costa, F.; Monteagudo, A.; Araujo, A.; Pena-Cruz, A.; Torres Lezama, A.; Castilho, C.V.; Neill, D.; Vilanova, E.; Oblitas Mendoza, E.M.; Alvarez, E.; Honorio, E.N.; Parada, G.A.; ter Steege, H.|info:eu-repo/dai/nl/075217120; Ramirez-Angulo, H.; Chave, J.; Terborgh, J.W.; Schietti, J.; Silveira, M.; Penuela-Mora, M.C.; Schwarz, M.; Banki, O.; Philips, O.L.; Thomas, R.; Vasquez, R.; Brienen, R.J.W.; Feldpausch, T.R.; Killeen, T.J.; Baker, T.R.; Magnusson, W.E.; Mahli, Y.

    2014-01-01

    Background: Trees and arborescent palms adopt different rooting strategies and responses to physical limitations imposed by soil structure, depth and anoxia. However, the implications of these differences for understanding variation in the relative abundance of these groups have not been explored.

  15. Oxygen delivery is not a limiting factor during post-exercise recovery in healthy young adults

    NARCIS (Netherlands)

    R.T. Mankowski (Robert T.); Niemeijer, V.M. (Victor M.); Jansen, J.P. (Jasper P.); Spraakman, L. (Lotte); Stam, H.J. (Henk J.); S.F.E. Praet (Stephan)

    2017-01-01

    textabstractPurpose It is still equivocal whether oxygen uptake recovery kinetics are limited by oxygen delivery and can be improved by supplementary oxygen. The present study aimed to investigate whether measurements of muscle and pulmonary oxygen uptake kinetics can be used to assess oxygen

  16. Ecosystem-based management and the wealth of ecosystems.

    Science.gov (United States)

    Yun, Seong Do; Hutniczak, Barbara; Abbott, Joshua K; Fenichel, Eli P

    2017-06-20

    We merge inclusive wealth theory with ecosystem-based management (EBM) to address two challenges in the science of sustainable management of ecosystems. First, we generalize natural capital theory to approximate realized shadow prices for multiple interacting natural capital stocks (species) making up an ecosystem. These prices enable ecosystem components to be better included in wealth-based sustainability measures. We show that ecosystems are best envisioned as portfolios of assets, where the portfolio's performance depends on the performance of the underlying assets influenced by their interactions. Second, changes in ecosystem wealth provide an attractive headline index for EBM, regardless of whether ecosystem wealth is ultimately included in a broader wealth index. We apply our approach to the Baltic Sea ecosystem, focusing on the interacting community of three commercially important fish species: cod, herring, and sprat. Our results incorporate supporting services embodied in the shadow price of a species through its trophic interactions. Prey fish have greater shadow prices than expected based on market value, and predatory fish have lower shadow prices than expected based on market value. These results are because correctly measured shadow prices reflect interdependence and limits to substitution. We project that ecosystem wealth in the Baltic Sea fishery ecosystem generally increases conditional on the EBM-inspired multispecies maximum sustainable yield management beginning in 2017, whereas continuing the current single-species management generally results in declining wealth.

  17. Vertical structure and pH as factors for chitinolytic and pectinolytic microbial community of soils and terrestrial ecosystems of different climatic zones

    Science.gov (United States)

    Lukacheva, Evgeniya; Natalia, Manucharova

    2016-04-01

    Chitin is a naturally occurring fibre-forming polymer that plays a protective role in many lower animals similar to that of cellulose in plants. Also it's a compound of cell walls of fungi. Chemically it is a long-chain unbranched polysaccharide made of N-acetylglucosamine residues; it is the second most abundant organic compound in nature, after cellulose. Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. Roots of the plants and root crops contain pectin. Chitin and pectin are widely distributed throughout the natural world. Structural and functional features of the complex microbial degradation of biopolymers one of the most important direction in microbial ecology. But there is no a lot of data concerns degradation in vertical structure of terrestrial ecosystems and detailed studies concerning certain abiotic features as pH. Microbial complexes of natural areas were analyzed only as humus horizons (A1) of the soil profile. Only small part of microbial community could be studied with this approach. It is known that ecosystems have their own structure. It is possible to allocate some vertical tiers: phylloplane, litter (soil covering), soil. We investigated chitinolytic and pectinolytic microbial communities dedicated to different layers of the ecosystems. Also it was described depending on pH dominated in certain ecosystem with certain conditions. Quantity of eukaryote and procaryote organisms increased in the test samples with chitin and pectin. Increasing of eukaryote in samples with pectin was more then in samples with chitin. Also should be noted the significant increasing of actinomycet's quantity in the samples with chitin in comparison with samples with pectin. The variety and abundance of bacteria in the litter samples increased an order of magnitude as compared to other probes. Further prokaryote community was investigated by method FISH (fluorescence in situ hybridization). FISH is a cytogenetic

  18. Working group 7: Ecosystems

    International Nuclear Information System (INIS)

    Verheyen, R.

    1976-01-01

    The purpose of this article is to evaluate the environmental impact of nuclear power plants. The effects of ionizing radiations, of the thermal and chemical pollution on aquatic ecosystems as well as on terrestrial ecosystems have been estimated. After a general survey of such effects and their interaction, practical conclusions in regard to determined areas such as Meuse-Escaut marine and the coast have been drawn. The contamination effects of food chains have been evaluted under deliberately pessimistic conditions with regard to the choice of the radionuclide as well as of concentration factors. Following the biodegradation conditions of the surface waters, criteria for the quality of the aquatic ecosystems have been established. Finally, attention has been paid on certain factors affecting the site selection especially within the frame of the nature conservation. The effects of cooling towers have been also considered. (G.C.)

  19. Strategic ecosystems of Colombia

    International Nuclear Information System (INIS)

    Marquez Calle German

    2002-01-01

    The author relates the ecosystems in Colombia, he makes a relationship between ecosystems and population, utility of the ecosystems, transformation of the ecosystems and poverty and he shows a methodology of identification of strategic ecosystems

  20. Physics of Limiting Phenomena in Superconducting Microwave Resonators: Vortex Dissipation, Ultimate Quench and Quality Factor Degradation Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Checchin, Mattia [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-12-01

    Superconducting niobium accelerating cavities are devices operating in radio-frequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associate d to the

  1. Limited promiscuity of HLA-DRB1 presented peptides derived of blood coagulation factor VIII

    NARCIS (Netherlands)

    van Haren, Simon D.; Wroblewska, Aleksandra; Herczenik, Eszter; Kaijen, Paul H.; Ruminska, Aleksandra; ten Brinke, Anja; Meijer, Alexander B.; Voorberg, Jan

    2013-01-01

    The formation of inhibitory antibodies directed against coagulation factor VIII (FVIII) is a severe complication in the treatment of hemophilia A patients. The induction of anti-FVIII antibodies is a CD4(+) T cell-dependent process. Activation of FVIII-specific CD4(+) T cells is dependent on the

  2. Referral for genetic counselling during pregnancy: limited alertness and awareness about genetic risk factors among GPs

    NARCIS (Netherlands)

    Aalfs, Cora M.; Smets, Ellen M. A.; de Haes, Hanneke C. J. M.; Leschot, Nico J.

    2003-01-01

    Background. In many countries, GPs play a key role in the referral to other medical specialists. Referral for reproductive genetic counselling during a pregnancy of women with a genetic risk factor already present before pregnancy has many disadvantages. Nevertheless, some 10-20% of the counsellees

  3. Habitats as surrogates of taxonomic and functional fish assemblages in coral reef ecosystems: a critical analysis of factors driving effectiveness.

    Directory of Open Access Journals (Sweden)

    Simon Van Wynsberge

    Full Text Available Species check-lists are helpful to establish Marine Protected Areas (MPAs and protect local richness, endemicity, rarity, and biodiversity in general. However, such exhaustive taxonomic lists (i.e., true surrogate of biodiversity require extensive and expensive censuses, and the use of estimator surrogates (e.g., habitats is an appealing alternative. In truth, surrogate effectiveness appears from the literature highly variable both in marine and terrestrial ecosystems, making it difficult to provide practical recommendations for managers. Here, we evaluate how the biodiversity reference data set and its inherent bias can influence effectiveness. Specifically, we defined habitats by geomorphology, rugosity, and benthic cover and architecture criteria, and mapped them with satellite images for a New-Caledonian site. Fish taxonomic and functional lists were elaborated from Underwater Visual Censuses, stratified according to geomorphology and exposure. We then tested if MPA networks designed to maximize habitat richness, diversity and rarity could also effectively maximize fish richness, diversity, and rarity. Effectiveness appeared highly sensitive to the fish census design itself, in relation to the type of habitat map used and the scale of analysis. Spatial distribution of habitats (estimator surrogate's distribution, quantity and location of fish census stations (target surrogate's sampling, and random processes in the MPA design all affected effectiveness to the point that one small change in the data set could lead to opposite conclusions. We suggest that previous conclusions on surrogacy effectiveness, either positive or negative, marine or terrestrial, should be considered with caution, except in instances where very dense data sets were used without pseudo-replication. Although this does not rule out the validity of using surrogates of species lists for conservation planning, the critical joint examination of both target and estimator

  4. Habitats as surrogates of taxonomic and functional fish assemblages in coral reef ecosystems: a critical analysis of factors driving effectiveness.

    Science.gov (United States)

    Van Wynsberge, Simon; Andréfouët, Serge; Hamel, Mélanie A; Kulbicki, Michel

    2012-01-01

    Species check-lists are helpful to establish Marine Protected Areas (MPAs) and protect local richness, endemicity, rarity, and biodiversity in general. However, such exhaustive taxonomic lists (i.e., true surrogate of biodiversity) require extensive and expensive censuses, and the use of estimator surrogates (e.g., habitats) is an appealing alternative. In truth, surrogate effectiveness appears from the literature highly variable both in marine and terrestrial ecosystems, making it difficult to provide practical recommendations for managers. Here, we evaluate how the biodiversity reference data set and its inherent bias can influence effectiveness. Specifically, we defined habitats by geomorphology, rugosity, and benthic cover and architecture criteria, and mapped them with satellite images for a New-Caledonian site. Fish taxonomic and functional lists were elaborated from Underwater Visual Censuses, stratified according to geomorphology and exposure. We then tested if MPA networks designed to maximize habitat richness, diversity and rarity could also effectively maximize fish richness, diversity, and rarity. Effectiveness appeared highly sensitive to the fish census design itself, in relation to the type of habitat map used and the scale of analysis. Spatial distribution of habitats (estimator surrogate's distribution), quantity and location of fish census stations (target surrogate's sampling), and random processes in the MPA design all affected effectiveness to the point that one small change in the data set could lead to opposite conclusions. We suggest that previous conclusions on surrogacy effectiveness, either positive or negative, marine or terrestrial, should be considered with caution, except in instances where very dense data sets were used without pseudo-replication. Although this does not rule out the validity of using surrogates of species lists for conservation planning, the critical joint examination of both target and estimator surrogates is needed

  5. Small Boreal Lake Ecosystem Evolution under the Influence of Natural and Anthropogenic Factors: Results of Multidisciplinary Long-Term Study

    Directory of Open Access Journals (Sweden)

    Liudmila Shirokova

    2016-07-01

    Full Text Available Small aquatic ecosystems of the boreal zone are known to be most sensitive indicators of on-going environmental change as well as local anthropogenic pressure, while being highly vulnerable to external impacts. Compared to rather detailed knowledge of the evolution of large and small lakes in Scandinavia and Canada, and large lakes in Eurasia, highly abundant small boreal lakes of northwest Russia have received very little attention, although they may become important centers of attraction of growing rural population in the near future. Here we present the results of a multidisciplinary, multi-annual study of a small boreal humic lake of NW Russia. A shallow (3 m and a deep (16 m site of this lake were regularly sampled for a range of chemical and biological parameters. Average multi-daily, summer-time values of the epilimnion (upper oxygenated layer of the lake provided indications of possible trends in temperature, nutrients, and bacterio-plankton concentration that revealed the local pollution impact in the shallow zone and overall environmental trend in the deep sampling point of the lake. Organic phosphorus, nitrate, and lead were found to be most efficient tracers of local anthropogenic pollution, especially visible in the surface layer of the shallow site of the lake. Cycling of trace elements between the epilimnion and hypolimnion is tightly linked to dissolved organic matter speciation and size fractionation due to the dominance of organic and organo-ferric colloids. The capacity of lake self-purification depends on the ratio of primary productivity to mineralization of organic matter. This ratio remained >1 both during winter and summer periods, which suggests a high potential of lake recovery from the input of allochthonous dissolved organic matter and local anthropogenic pollution.

  6. Late presentation for HIV care in central Haiti: factors limiting access to care.

    Science.gov (United States)

    Louis, C; Ivers, L C; Smith Fawzi, M C; Freedberg, K A; Castro, A

    2007-04-01

    Many patients with HIV infection present for care late in the course of their disease, a factor which is associated with poor prognosis. Our objective was to identify factors associated with late presentation for HIV care among patients in central Haiti. Thirty-one HIV-positive adults, approximately 10% of the HIV-infected population followed at a central Haiti hospital, participated in this research study. A two-part research tool that included a structured questionnaire and an ethnographic life history interview was used to collect quantitative as well as qualitative data about demographic factors related to presentation for HIV care. Sixty-five percent of the patients in this study presented late for HIV care, as defined by CD4 cell count below 350 cells/mm3. Factors associated with late presentation included male sex, older age, patient belief that symptoms are not caused by a medical condition, greater distance from the medical clinic, lack of prior access to effective medical care, previous requirement to pay for medical care, and prior negative experience at local hospitals. Harsh poverty was a striking theme among all patients interviewed. Delays in presentation for HIV care in rural Haiti are linked to demographic, socioeconomic and structural factors, many of which are rooted in poverty. These data suggest that a multifaceted approach is needed to overcome barriers to early presentation for care. This approach might include poverty alleviation strategies; provision of effective, reliable and free medical care; patient outreach through community health workers and collaboration with traditional healers.

  7. Risky sexual behavior among rural female adolescents in Malaysia: a limited role of protective factors.

    Science.gov (United States)

    Ahmadian, Maryam; Hamsan, Hanina H; Abdullah, Haslinda; Samah, Asnarulkhadi Abu; Noor, Amna Md

    2014-03-23

    This paper presents the findings of a cross-sectional survey on the risk and protective factors of premarital sexual behavior among rural female adolescents in Peninsular Malaysia. We investigated data on 770 female respondents aged 13-17 years in rural areas to identify predictive factors for premarital sexual intercourse. Data were analyzed using bivariate and multivariate regression. Specific socio-demographic factors, psychological and family domains, peer delinquency, and knowledge and attitudes about sexuality were considered in risky sexual behaviors in rural Malay girls. The effects of other covariates for premarital sexual intercourse were controlled by logistic regression model. Of the 770 rural female students, about 3.2% of respondents reported experience of sexual intercourse in the past three months. Out of those sexually active girls, 36% were 17 years old and 20% stated having sexual intercourse with more than one partner, and 72% did not use contraception during the most recent sexual intercourse. Midnight activities, peer-sexual disorder, self-evaluation, and attitude toward sexual health were significant predictors of sexual intercourse in rural girls in Malaysia. The finding highlights the impact of psychological factors and peer group influences on the challenges of premarital sexual behavior among rural girls and the notion of school-based sexual health education for adolescents. This study triggers other researchers take into account a comprehensive view of protective factors operating in adolescents' risky sexual behaviors in Asian culture seeing that family domain variables, unexpectedly, exerted no predicting influence on sexually active female teens in rural areas in Malaysia.

  8. Risky Sexual Behavior among Rural Female Adolescents in Malaysia: A Limited Role of Protective Factors

    Science.gov (United States)

    Ahmadian, Maryam; Hamsan, Hanina H.; Abdullah, Haslinda; Samah, Asnarulkhadi Abu; Noor, Amna Md

    2014-01-01

    Purpose: This paper presents the findings of a cross-sectional survey on the risk and protective factors of premarital sexual behavior among rural female adolescents in Peninsular Malaysia. Methods: We investigated data on 770 female respondents aged 13-17 years in rural areas to identify predictive factors for premarital sexual intercourse. Data were analyzed using bivariate and multivariate regression. Specific socio-demographic factors, psychological and family domains, peer delinquency, and knowledge and attitudes about sexuality were considered in risky sexual behaviors in rural Malay girls. The effects of other covariates for premarital sexual intercourse were controlled by logistic regression model. Results: Of the 770 rural female students, about 3.2% of respondents reported experience of sexual intercourse in the past three months. Out of those sexually active girls, 36% were 17 years old and 20% stated having sexual intercourse with more than one partner, and 72% did not use contraception during the most recent sexual intercourse. Midnight activities, peer-sexual disorder, self-evaluation, and attitude toward sexual health were significant predictors of sexual intercourse in rural girls in Malaysia. Conclusion: The finding highlights the impact of psychological factors and peer group influences on the challenges of premarital sexual behavior among rural girls and the notion of school-based sexual health education for adolescents. This study triggers other researchers take into account a comprehensive view of protective factors operating in adolescents’ risky sexual behaviors in Asian culture seeing that family domain variables, unexpectedly, exerted no predicting influence on sexually active female teens in rural areas in Malaysia. PMID:24762359

  9. Nitrogen saturation in stream ecosystems.

    Science.gov (United States)

    Earl, Stevan R; Valett, H Maurice; Webster, Jackson R

    2006-12-01

    The concept of nitrogen (N) saturation has organized the assessment of N loading in terrestrial ecosystems. Here we extend the concept to lotic ecosystems by coupling Michaelis-Menten kinetics and nutrient spiraling. We propose a series of saturation response types, which may be used to characterize the proximity of streams to N saturation. We conducted a series of short-term N releases using a tracer (15NO3-N) to measure uptake. Experiments were conducted in streams spanning a gradient of background N concentration. Uptake increased in four of six streams as NO3-N was incrementally elevated, indicating that these streams were not saturated. Uptake generally corresponded to Michaelis-Menten kinetics but deviated from the model in two streams where some other growth-critical factor may have been limiting. Proximity to saturation was correlated to background N concentration but was better predicted by the ratio of dissolved inorganic N (DIN) to soluble reactive phosphorus (SRP), suggesting phosphorus limitation in several high-N streams. Uptake velocity, a reflection of uptake efficiency, declined nonlinearly with increasing N amendment in all streams. At the same time, uptake velocity was highest in the low-N streams. Our conceptual model of N transport, uptake, and uptake efficiency suggests that, while streams may be active sites of N uptake on the landscape, N saturation contributes to nonlinear changes in stream N dynamics that correspond to decreased uptake efficiency.

  10. Theory of factors limiting high gradient operation of warm accelerating structures

    Energy Technology Data Exchange (ETDEWEB)

    Nusinovich, Gregory S. [Univ. of Maryland, College Park, MD (United States)

    2014-07-22

    This report consists of two parts. In the first part we describe a study of the heating of microprotrusions on surfaces of accelerating structures. This ;process is believed to lead to breakdown in these structures. Our study revealed that for current accelerator parameters melting should not occur due to space charge limitations of the current emitted by a protrusion. The second part describes a novel concept to develop THz range sources based on harmonic cyclotron masers for driving future colliders. This work was stimulated by a recent request of SLAC to develop high power, high-efficiency sources of sub-THz radiation for future high-gradient accelerators.

  11. Factors limiting the implementation of mechanical harvesting of sugarcane in Campos dos Goytacazes, RJ, Brazil

    Directory of Open Access Journals (Sweden)

    Cristóbal Soto Solano

    Full Text Available ABSTRACT The objective of this research was to identify and characterize the main technical factors that affect the deployment of the mechanized harvesting of sugarcane in Campos dos Goytacazes, Rio de Janeiro, Brazil. In general, it can be stated there were restrictive factors related to machinery, administrative management, and technical planning. We identified significant technical restrictions in the planting system, particularly in relation to the size and shape of the plots, length of the rows, row spacing, and inadequate varieties. For efficient use of mechanized harvesting, a technical planning is necessary with changes in the cropping system, adopting wider and more uniform plots regarding to its format, with rows over 500 m length and row spacing of 1.50 m and upright, productive, and deep-rooted varieties.

  12. HSL MI28: An Efficient and Robust Limited-Memory Incomplete Cholesky Factorization Code

    Czech Academy of Sciences Publication Activity Database

    Scott, J.; Tůma, Miroslav

    2014-01-01

    Roč. 40, č. 4 (2014), Art icle number 24 ISSN 0098-3500 R&D Projects: GA ČR GA13-06684S Grant - others:EPSRC(GB) EP/I013067/1 Institutional support: RVO:67985807 Keywords : preconditioning * sparse linear systems * incomplete decompositions * preconditioned iterative methods Subject RIV: IN - Informatics, Computer Science Impact factor: 1.863, year: 2014

  13. HSL MI28: An Efficient and Robust Limited-Memory Incomplete Cholesky Factorization Code

    Czech Academy of Sciences Publication Activity Database

    Scott, J.; Tůma, Miroslav

    2014-01-01

    Roč. 40, č. 4 (2014), Article number 24 ISSN 0098-3500 R&D Projects: GA ČR GA13-06684S Grant - others:EPSRC(GB) EP/I013067/1 Institutional support: RVO:67985807 Keywords : preconditioning * sparse linear systems * incomplete decompositions * preconditioned iterative methods Subject RIV: IN - Informatics, Computer Science Impact factor: 1.863, year: 2014

  14. Factors that limit access to dental care for adults with spinal cord injury.

    Science.gov (United States)

    Yuen, Hon K; Wolf, Bethany J; Bandyopadhyay, Dipankar; Magruder, Kathryn M; Selassie, Anbesaw W; Salinas, Carlos F

    2010-01-01

    This study investigated dental care service utilization among adults with spinal cord injury (SCI) and identified barriers and other factors affecting utilization among this population. There were 192 subjects with SCI who participated in the oral health survey assessing dental care service utilization and they were compared with subjects from the 2004 Behavioral Risk Factors Surveillance System (BRFSS). There was no significant difference in the proportion of subjects with SCI who visited the dentist for any reason in the past year compared to the general population (65.5% vs. 68.8%, p= .350). However, subjects with SCI were less likely to go to the dentist for a dental cleaning in the past year compared to the general population (54.6% vs. 69.4%, p dental care were cost (40.1%), physical barriers (22.9%), and dental fear (15.1%). Multivariate modeling showed that physical barriers and fear of dental visits were the two significant factors deterring subjects from dental visits in the past year. Physical barriers preventing access to dental facilities and dental fear are prevalent and significantly impede the delivery of dental health care to adults with SCI. Dentists should undertake necessary physical remodeling of their facilities to accommodate wheelchair users and implement appropriate strategies for the management of dental fear among patients with SCI.

  15. Obscuring ecosystem function with application of the ecosystem services concept.

    Science.gov (United States)

    Peterson, Markus J; Hall, Damon M; Feldpausch-Parker, Andrea M; Peterson, Tarla Rai

    2010-02-01

    Conservationists commonly have framed ecological concerns in economic terms to garner political support for conservation and to increase public interest in preserving global biodiversity. Beginning in the early 1980s, conservation biologists adapted neoliberal economics to reframe ecosystem functions and related biodiversity as ecosystem services to humanity. Despite the economic success of programs such as the Catskill/Delaware watershed management plan in the United States and the creation of global carbon exchanges, today's marketplace often fails to adequately protect biodiversity. We used a Marxist critique to explain one reason for this failure and to suggest a possible, if partial, response. Reframing ecosystem functions as economic services does not address the political problem of commodification. Just as it obscures the labor of human workers, commodification obscures the importance of the biota (ecosystem workers) and related abiotic factors that contribute to ecosystem functions. This erasure of work done by ecosystems impedes public understanding of biodiversity. Odum and Odum's radical suggestion to use the language of ecosystems (i.e., emergy or energy memory) to describe economies, rather than using the language of economics (i.e., services) to describe ecosystems, reverses this erasure of the ecosystem worker. Considering the current dominance of economic forces, however, implementing such solutions would require social changes similar in magnitude to those that occurred during the 1960s. Niklas Luhmann argues that such substantive, yet rapid, social change requires synergy among multiple societal function systems (i.e., economy, education, law, politics, religion, science), rather than reliance on a single social sphere, such as the economy. Explicitly presenting ecosystem services as discreet and incomplete aspects of ecosystem functions not only allows potential economic and environmental benefits associated with ecosystem services, but also

  16. Critical analysis of excessive utilization of crude protein in ruminants ration: impact on environmental ecosystem and opportunities of supplementation of limiting amino acids-a review.

    Science.gov (United States)

    Abbasi, Imtiaz Hussain Raja; Abbasi, Farzana; Abd El-Hack, Mohamed E; Abdel-Latif, Mervat A; Soomro, Rab N; Hayat, Khawar; Mohamed, Mohamed A E; Bodinga, Bello M; Yao, Junhu; Cao, Yangchun

    2018-01-01

    Protein quality plays a key role than quantity in growth, production, and reproduction of ruminants. Application of high concentration of dietary crude protein (CP) did not balance the proportion of these limiting amino acids (AA) at duodenal digesta of high producing dairy cow. Thus, dietary supplementation of rumen-protected AA is recommended to sustain the physiological, productive, and reproductive performance of ruminants. Poor metabolism of high CP diets in rumen excretes excessive nitrogen (N) through urine and feces in the environment. This excretion is usually in the form of nitrous oxide, nitric oxide, nitrate, and ammonia. In addition to producing gases like methane, hydrogen carbon dioxide pollutes and has a potentially negative impact on air, soil, and water quality. Data specify that supplementation of top-limiting AA methionine and lysine (Met + Lys) in ruminants' ration is one of the best approaches to enhance the utilization of feed protein and alleviate negative biohazards of CP in ruminants' ration. In conclusion, many in vivo and in vitro studies were reviewed and reported that low dietary CP with supplemental rumen-protected AA (Met + Lys) showed a good ability to reduce N losses or NH 3 . Also, it helps in declining gases emission and decreasing soil or water contamination without negative impacts on animal performance. Finally, further studies are needed on genetic and molecular basis to explain the impact of Met + Lys supplementation on co-occurrence patterns of microbiome of rumen which shine new light on bacteria, methanogen, and protozoal interaction in ruminants.

  17. Radio-capacity of ecosystems

    International Nuclear Information System (INIS)

    Kultakhmedov, Yu.; Kultakhmedova-Vyshnyakova, V.

    1997-01-01

    This paper consider a universal approach to ecosystems of different types, based on representation of their radio-capacity. The concept of ecosystem includes reproduction of components (bio-productivity) and conditions such as maintaining of environment quality. Radio-capacity in the case of radionuclide pollution appears in accumulation and redistribution of radionuclides in the ecosystem. As a result the radionuclides are redistributed and buried in soil or lake bottom sediments. Estimation models for the radio-capacity of water and terrestrial ecosystems are represented. The calculations of the radio-capacity factor of water ecosystems are performed, and the high radio-capacity of a freshwater reservoir (F=0.6-0.8) and extremely high radio-capacity of a reservoir cascade (F c =0.99) is shown material from the Dnieper's cascade reservoirs. The methods of radio-capacity estimation of agroecosystems, wood and marine ecosystems are developed. (authors)

  18. Investigation on the Quality Factor Limit of the (111 Silicon Based Disk Resonator

    Directory of Open Access Journals (Sweden)

    Xin Zhou

    2018-01-01

    Full Text Available Quality factor is one of the most important parameters for a MEMS resonator. Most MEMS resonators are dominated by thermoelastic dissipation (TED. This paper demonstrates that the TED in a disk resonator that is made of (111 single-crystal silicon is surpassed by clamping loss. The stiffness-mass decoupling design method, combined with reducing the beam width, was used to engineer high QTED. Experiments show that Q of the (111 disk resonator have an upper boundary that is determined by the clamping loss caused by the unbalanced out-of-plane displacement. The origin of the out-of-plane displacement is explained by theory and simulation.

  19. Original nerve growth factor mimetic dipeptide GK-2 limits the manifestations of hemorrhagic stroke in rats.

    Science.gov (United States)

    Kraineva, V A; Gudasheva, T A; Kotelnikova, S O; Antipova, T A; Seredenin, S B

    2013-03-01

    The protective effects of a new low-molecular-weight mimetic of nerve growth factor hexamethylene diamide bis-(N-monosuccinyl-L-glutamine-L-lysine; GK-2) were studied on the experimental model of hemorrhagic stroke (intracerebral posttraumatic hematoma) in rats. Intraperitoneal injections of GK-2 in a dose of 1 mg/kg 4 and 24 h after surgery and 24 h before testing the CNS function on days 3, 7, and 14 prevent death of experimental animals, reduce the neurological deficit, and normalized behavior.

  20. Limiting factors for vegetation development during the early late glacial in Denmark

    DEFF Research Database (Denmark)

    Mortensen, Morten Fischer; Odgaard, Bent Vad; Jessen, Cathrine

    periods at Slotseng was dominated by Betula nana and Dryas octopetala and associated with many herbs of open habitats. Late-glacial pollen records are frequently interpreted only in the context of climate change. However, the forcing mechanisms of vegetational change may shift over time between e...... type (peat/gyttja) and δ18O from assumedly synchronous levels in the NGRIP and GRIP ice-cores. Our series of RDA’s show that climate variations as expressed by proxy ice-core δ18O had limited correlation with our pollen data during these shorter intervals. The lack of immediate palynological response...... glacial vegetation changes. This result strongly suggests that late glacial pollen records may not be interpreted merely as a direct climate proxy....

  1. Factors limiting vocal-tract length discrimination in cochlear implant simulations.

    Science.gov (United States)

    Gaudrain, Etienne; Başkent, Deniz

    2015-03-01

    Perception of voice characteristics allows normal hearing listeners to identify the gender of a speaker, and to better segregate speakers from each other in cocktail party situations. This benefit is largely driven by the perception of two vocal characteristics of the speaker: The fundamental frequency (F0) and the vocal-tract length (VTL). Previous studies have suggested that cochlear implant (CI) users have difficulties in perceiving these cues. The aim of the present study was to investigate possible causes for limited sensitivity to VTL differences in CI users. Different acoustic simulations of CI stimulation were implemented to characterize the role of spectral resolution on VTL, both in terms of number of channels and amount of channel interaction. The results indicate that with 12 channels, channel interaction caused by current spread is likely to prevent CI users from perceiving VTL differences typically found between male and female speakers.

  2. The back squat: A proposed assessment of functional deficits and technical factors that limit performance

    Science.gov (United States)

    Myer, Gregory D.; Kushner, Adam M.; Brent, Jensen L.; Schoenfeld, Brad J.; Hugentobler, Jason; Lloyd, Rhodri S.; Vermeil, Al; Chu, Donald A.; Harbin, Jason; McGill, Stuart M.

    2014-01-01

    Fundamental movement competency is essential for participation in physical activity and for mitigating the risk of injury, which are both key elements of health throughout life. The squat movement pattern is arguably one of the most primal and critical fundamental movements necessary to improve sport performance, to reduce injury risk and to support lifelong physical activity. Based on current evidence, this first (1 of 2) report deconstructs the technical performance of the back squat as a foundation training exercise and presents a novel dynamic screening tool that incorporates identification techniques for functional deficits that limit squat performance and injury resilience. The follow-up report will outline targeted corrective methodology for each of the functional deficits presented in the assessment tool. PMID:25506270

  3. Use of experimental ecosystems in regulatory decision making

    Science.gov (United States)

    La Point, Thomas W.; Perry, James A.

    1989-01-01

    Tiered testing for the effects of chemicals on aquatic ecosystems has begun to include tests at the ecosystem level as a component in pesticide regristration. Because such tests are expensive, regulators and industry need to know what additional information they can gain from such tests relative to the costs of the simpler single-species toxicity bioassays. Requirements for ecosystem-level testing have developed because resource managers have not fully understood the implications of potential damage to resources without having evaluations of the predicted impacts under field conditions. We review approaches taken in the use of experimental ecosystems, discuss benefits and limitations of small- and large-scale ecosystem tests, and point to correlative approaches between laboratory and field toxicity testing.Laboratory experimental ecosystems (microcosms) have been successfully used to measure contaminant bioavailability, to determine routes of uptake in moderately complex aquatic systems, and to isolate factors modifying contaminant uptake into the biota. Such factors cannot be as readily studied in outdoor experimental ecosystems because direct cause-and-effect relations are often confounded and difficult to isolate. However, laboratory tests can be designed to quantify the relations among three variables: known concentrations of Stressors; specific sublethal behavioral, biochemical, and physiological effects displayed by organisms; and responses that have been observed in ecosystem-level analyses. For regulatory purposes, the specificity of test results determines how widely they can be applied. Ecotoxicological research should be directed at attempts to identify instances where single-species testing would be the appropriate level of analysis for identifying critical ecological endpoints and for clarifying relationships between ecosystem structure and function, and where it would be inadequate for a given level of analysis.

  4. Terrestrial Ecosystem Responses to Global Change: A Research Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Ecosystems Working Group,

    1998-09-23

    , nutrients). With limited resources, these complementary experiments should be focused in high-priority ecosystems, with experimental treatments designed to address the major uncertainties in each system. Critical ecosystems, both managed and unmanaged, have been identified using the above criteria and key uncertainties in current understanding of ecosystem processes used to identify critical issues and experiments. The sizes of both the whole-ecosystem experiments and the multifactor experimental treatment units must be based on the sizes of the dominant organisms, the scale of major processes in each system, and the spatial heterogeneity of each system. For example, large-scale ecosystem manipulations in temperate forests should evaluate at a minimum CO{sub 2} and temperature and could be conducted on small, gauged catchments. The multifactor process experiments should address all major environmental driving variables, and the treatment units should be large enough to include multiple individuals of the major tree species. This approach represents a fundamental shift in the scale and integration of experimental ecosystem research: from the current small-scale, single- or two-factor experiments in simple natural or artificial ecosystems to highly coordinated, large-scale, replicated experiments in complex ecosystems, with multiple interacting factors being evaluated at two (or more) complementary levels of spatial scale and process resolution. These experiments will require an unprecedented long-term funding commitment and concentration of large-scale experimental research at a few major sites, with significant new investment in infrastructure to support large interdisciplinary teams of scientists.

  5. Process-Based Thinking in Ecosystem Education

    Science.gov (United States)

    Jordan, Rebecca C.; Gray, Steven A.; Brooks, Wesley R.; Honwad, Sameer; Hmelo-Silver, Cindy E.

    2013-01-01

    Understanding complex systems such as ecosystems is difficult for young K-12 students, and students' representations of ecosystems are often limited to nebulously defined relationships between macro-level structural components inherent to the ecosystem in focus (rainforest, desert, pond, etc.) instead of generalizing processes across ecosystems…

  6. [Factors limiting distribution of the rare lichen species Lobaria pulmonaria (in forests of the Kologriv Forest Nature Reserve)].

    Science.gov (United States)

    Ivanova, N V

    2015-01-01

    The distribution patterns and coenotic confines ofthe epiphytic lichen Lobaria pulmonaria have been studied. The factors limiting the habitat of this rare lichen species in the Kologriv Forest Nature Reserve (southern taiga subzone) have been revealed. It has been shown that L. pulmonaria is attracted to forest areas, which are less affected by humans and characterized by better light conditions than other communities. It has been found that L. pulmonaria is able to colonize trees at various ontogenetic states, beginning from virginal ones.

  7. Flavin as an Indicator of the Rate-Limiting Factor for Microbial Current Production in Shewanella oneidensis MR-1

    International Nuclear Information System (INIS)

    Saito, Junki; Hashimoto, Kazuhito; Okamoto, Akihiro

    2016-01-01

    Microbial electrode catalysis such as microbial fuel cells or electrosynthesis involves electron exchange with the electrodes located at the cell exterior; i.e., extracellular electron transport (EET). Despite the vast amount of research on the kinetics of EET to optimize the catalysis rate, the relevance of other factors, including upstream metabolic reactions, has scarcely been investigated. Herein, we report an in vivo electrochemical assay to confirm whether EET limits anodic current production (j) for the lactate oxidation of Shewanella oneidensis MR-1. Addition of riboflavin, which specifically enhances the EET rate, increased j only in the early phase before j saturation. In contrast, when we removed a trace metal ion necessary for upstream reactions from the electrolyte, a significant decrease in j and the lactate consumption rate was observed only after j saturation. These data suggest that the limiting factor for j shifted from EET to upstream reactions, highlighting the general importance of enhancing, for example, microbial metabolism, especially for long-standing practical applications. Our concept to specifically control the rate of EET could be applicable to other bioelectrode catalysis systems as a strategy to monitor their rate-limiting factors.

  8. A measurement of the QCD colour factors and a limit on the light gluino

    CERN Document Server

    Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Odier, P; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Miquel, R; Mir, L M; Orteu, S; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Bazarko, A O; Bright-Thomas, P G; Cattaneo, M; Cerutti, F; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Lutters, G; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rizzo, G; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Turnbull, R M; Becker, U; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Schmidt, M; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Stacey, A M; Williams, M D; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Williams, M I; Galla, A; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Konstantinidis, N P; Leroy, O; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, A; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Schune, M H; Simion, S; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1997-01-01

    Using data collected from 1992 to 1995 with the ALEPH detector at LEP, a measurement of the colour factor ratios CA/CF and TF/CF and the strong coupling constant $\\overline{\\alpha}_s = CF \\alpha_s(Mz)/ (2\\pi)$ has been performed by fitting theoretical predictions simultaneously to the measured differential two-jet rate and angular distributions in four-jet events. The result is found to be in excellent agreement with QCD, CA/CF = 2.20 +- 0.09 (stat) +- 0.13 (syst) , TF/CF = 0.29 +- 0.05 (stat) +- 0.06 (syst) . Fixing CA/CF$ and TF/CF to the QCD values permits a determination of $\\alpha_s(Mz)$ and nf, the number of active flavours. With this measurement the existence of a gluino with mass below 6.3 GeV/c^2 is excluded at 95% confidence level.

  9. Bioanode as a limiting factor to biocathode performance in microbial electrolysis cells.

    Science.gov (United States)

    Lim, Swee Su; Yu, Eileen Hao; Daud, Wan Ramli Wan; Kim, Byung Hong; Scott, Keith

    2017-08-01

    The bioanode is important for a microbial electrolysis cell (MEC) and its robustness to maintain its catalytic activity affects the performance of the whole system. Bioanodes enriched at a potential of +0.2V (vs. standard hydrogen electrode) were able to sustain their oxidation activity when the anode potential was varied from -0.3 up to +1.0V. Chronoamperometric test revealed that the bioanode produced peak current density of 0.36A/m 2 and 0.37A/m 2 at applied potential 0 and +0.6V, respectively. Meanwhile hydrogen production at the biocathode was proportional to the applied potential, in the range from -0.5 to -1.0V. The highest production rate was 7.4L H 2 /(m 2 cathode area)/day at -1.0V cathode potential. A limited current output at the bioanode could halt the biocathode capability to generate hydrogen. Therefore maximum applied potential that can be applied to the biocathode was calculated as -0.84V without overloading the bioanode. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Exercise hyperthermia as a factor limiting physical performance - Temperature effect on muscle metabolism

    Science.gov (United States)

    Kozlowski, S.; Brzezinska, Z.; Kruk, B.; Kaciuba-Uscilko, H.; Greenleaf, J. E.

    1985-01-01

    The effect of trunk cooling on the muscle contents of ATP, ADP, AMP, creatine phosphate (CrP), and creatine, as well as of glycogen, some glycolytic intermediates, pyruvate, and lactate were assessed in 11 fasted dogs exercised at 20 C on treadmill to exhaustion. Without cooling, dogs were able to run 57 min, and their rectal (Tre) and muscle (Tm) temperatures increased to 41.8 and 43.0 C, respectively. Cooling with ice packs prolonged the ability to run by 45 percent, and resulted in lower Tre (by 1.1 C) and Tm (by 1.2 C). Depletion of muscle content of total high-energy phosphates (ATP + CrP) and glycogen, and increases in contents of AMP, pyruvate, and lactate were lower in cooled dogs than in non-cooled dogs. The muscle content of lactiate correlated positively with TM. These results indicate that hypothermia accelerates glycolysis, and shifts the equilibrium between high- and low-energy phosphates in favor of the latter. The adverse effect of hypothermia on muscle metabolism may be relevant to the limitation of endurance.

  11. Attitude of Healthcare Professionals: A Major Limiting Factor in Organ Donation from Brain-Dead Donors

    Directory of Open Access Journals (Sweden)

    Maciej Kosieradzki

    2014-01-01

    Full Text Available Public attitude toward deceased donor organ recovery in Poland is quite positive, with only 15% opposing to donation of their own organs, yet actual donation rate is only 16/pmp. Moreover, donation rate varies greatly (from 5 to 28 pmp in different regions of the country. To identify the barriers of organ donation, we surveyed 587 physicians involved in brain death diagnosis from regions with low (LDR and high donation rates (HDR. Physicians from LDR were twice more reluctant to start diagnostic procedure when clinical signs of brain death were present (14% versus 5.5% physicians from HDR who would not diagnose death, resp.. Twenty-five percent of LDR physicians (as opposed to 12% of physicians from HDR would either continue with intensive therapy or confirm brain death and limit to the so-called minimal therapy. Only 32% of LDR physicians would proceed with brain death diagnosis regardless of organ donation, compared to 67% in HDR. When donation was not an option, mechanical ventilation would be continued more often in LDR regions (43% versus 26.7%; P<0.01. In conclusion, low donation activity seems to be mostly due to medical staff attitude.

  12. Progress in Australian dendroclimatology: Identifying growth limiting factors in four climate zones.

    Science.gov (United States)

    Haines, Heather A; Olley, Jon M; Kemp, Justine; English, Nathan B

    2016-12-01

    Dendroclimatology can be used to better understand past climate in regions such as Australia where instrumental and historical climate records are sparse and rarely extend beyond 100years. Here we review 36 Australian dendroclimatic studies which cover the four major climate zones of Australia; temperate, arid, subtropical and tropical. We show that all of these zones contain tree and shrub species which have the potential to provide high quality records of past climate. Despite this potential only four dendroclimatic reconstructions have been published for Australia, one from each of the climate zones: A 3592year temperature record for the SE-temperate zone, a 350year rainfall record for the Western arid zone, a 140year rainfall record for the northern tropics and a 146year rainfall record for SE-subtropics. We report on the spatial distribution of tree-ring studies, the environmental variables identified as limiting tree growth in each study, and identify the key challenges in using tree-ring records for climate reconstruction in Australia. We show that many Australian species have yet to be tested for dendroclimatological potential, and that the application of newer techniques including isotopic analysis, carbon dating, wood density measurements, and anatomical analysis, combined with traditional ring-width measurements should enable more species in each of the climate zones to be used, and long-term climate records to be developed across the entire continent. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Improving substance information in USEtox®, part 2: Data for estimating fate and ecosystem exposure factors.

    Science.gov (United States)

    Saouter, Erwan; Aschberger, Karin; Fantke, Peter; Hauschild, Michael Z; Kienzler, Aude; Paini, Alicia; Pant, Rana; Radovnikovic, Anita; Secchi, Michela; Sala, Serenella

    2017-12-01

    The scientific consensus model USEtox ® has been developed since 2003 under the auspices of the United Nations Environment Programme-Society of Environmental Toxicology and Chemistry Life Cycle Initiative as a harmonized approach for characterizing human and freshwater toxicity in life cycle assessment and other comparative assessment frameworks. Using physicochemical substance properties, USEtox quantifies potential human toxicity and freshwater ecotoxicity impacts by combining environmental fate, exposure, and toxicity effects information, considering multimedia fate and multipathway exposure processes. The main source to obtain substance properties for USEtox 1.01 and 2.0 is the Estimation Program Interface (EPI Suite™) from the US Environmental Protection Agency. However, since the development of the original USEtox substance databases, new chemical regulations have been enforced in Europe, such as the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) and the Plant Protection Products regulations. These regulations require that a chemical risk assessment for humans and the environment is performed before a chemical is placed on the European market. Consequently, additional physicochemical property data and new toxicological endpoints are now available for thousands of chemical substances. The aim of the present study was to explore the extent to which the new available data can be used as input for USEtox-especially for application in environmental footprint studies-and to discuss how this would influence the quantification of fate and exposure factors. Initial results show that the choice of data source and the parameters selected can greatly influence fate and exposure factors, leading to potentially different rankings and relative contributions of substances to overall human toxicity and ecotoxicity impacts. Moreover, it is crucial to discuss the relevance of the exposure factor for freshwater ecotoxicity impacts, particularly

  14. Sewage sludge, compost and other representative organic wastes as agricultural soil amendments: Benefits versus limiting factors.

    Science.gov (United States)

    Alvarenga, Paula; Mourinha, Clarisse; Farto, Márcia; Santos, Teresa; Palma, Patrícia; Sengo, Joana; Morais, Marie-Christine; Cunha-Queda, Cristina

    2015-06-01

    Nine different samples of sewage sludges, composts and other representative organic wastes, with potential interest to be used as agricultural soil amendments, were characterized: municipal sewage sludge (SS1 and SS2), agro industrial sludge (AIS), municipal slaughterhouse sludge (MSS), mixed municipal solid waste compost (MMSWC), agricultural wastes compost (AWC), compost produced from agricultural wastes and sewage sludge (AWSSC), pig slurry digestate (PSD) and paper mill wastes (PMW). The characterization was made considering their: (i) physicochemical parameters, (ii) total and bioavailable heavy metals (Cd, Cr, Cu, Ni, Pb, Zn and Hg), (iii) organic contaminants, (iv) pathogenic microorganisms and (v) stability and phytotoxicity indicators. All the sludges, municipal or other, comply with the requirements of the legislation regarding the possibility of their application to agricultural soil (with the exception of SS2, due to its pathogenic microorganisms content), with a content of organic matter and nutrients that make them interesting to be applied to soil. The composts presented, in general, some constraints regarding their application to soil, and their impairment was due to the existence of heavy metal concentrations exceeding the proposed limit of the draft European legislation. As a consequence, with the exception of AWSSC, most compost samples were not able to meet these quality criteria, which are more conservative for compost than for sewage sludge. From the results, the composting of sewage sludge is recommended as a way to turn a less stabilized waste into a material that is no longer classified as a waste and, judging by the results of this work, with lower heavy metal content than the other composted materials, and without sanitation problems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Limits of metastability in amorphous ices: the neutron scattering Debye-Waller factor.

    Science.gov (United States)

    Amann-Winkel, Katrin; Löw, Florian; Handle, Philip H; Knoll, Wiebke; Peters, Judith; Geil, Burkhard; Fujara, Franz; Loerting, Thomas

    2012-12-21

    Recently, it became clear that relaxation effects in amorphous ices play a very important role that has previously been overlooked. The thermodynamic history of amorphous samples strongly affects their transition behavior. In particular, well-relaxed samples show higher thermal stability, thereby providing a larger window to investigate their glass transitions. We here present neutron scattering experiments using fixed elastic window scans on relaxed forms of amorphous ice, namely expanded high density amorphous ice (eHDA), a variant of low density amorphous ice (LDA-II) and hyperquenched glassy water (HGW). These amorphous ices are expected to be true glassy counterparts of deeply supercooled liquid water, therefore fast precursor dynamics of structural relaxation are expected to appear below the calorimetric glass transition temperature. The Debye-Waller factor shows a very weak sub-T(g) anomaly in some of the samples, which might be the signature of such fast precursor dynamics. However, we cannot find this behavior consistently in all samples at all reciprocal length scales of momentum transfer.

  16. Limitations of the toxic equivalency factor (TEF) approach for risk assessment of halogenated aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Safe, S. [Texas A and M Univ., College Station, TX (United States). Dept. of Veterinary Physiology and Pharmacology

    1995-12-31

    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons (HAHs) are present as complex mixtures of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) in most environmental matrices. Risk management of these mixtures utilize the toxic equivalency factor (TEF) approach in which the TCDD (dioxin) or toxic equivalents of a mixture is a summation of the congener concentration (Ci) times TEF{sub i} (potency relative to TCDD) where. TEQ{sub mixture} = {Sigma}[Cil] {times} TEF{sub i}. TEQs are determined only for those HAHs which are aryl hydrocarbon (Ah) receptor agonists and this approach assumes that the toxic or biochemical effects of individual compounds in a mixture are additive. Several in vivo and in vitro laboratory and field studies with different HAH mixtures have been utilized to validate the TEF approach. For some responses, the calculated toxicities of PCDD/PCDF and PCB mixtures predict the observed toxic potencies. However, for fetal cleft palate and immunotoxicity in mice, nonadditive (antagonistic) responses are observed using complex PCB mixtures or binary mixtures containing an Ah receptor agonist with 2,2{prime},4,4{prime},5,5{prime}-hexachlorobiphenyl (PCB153). The potential interactive effects of PCBs and other dietary Ah receptor antagonist suggest that the TEF approach for risk management of HAHs requires further refinement and should be used selectively.

  17. A transformation procedure for recalcitrant tomato by addressing transgenic plant-recovery limiting factors.

    Science.gov (United States)

    Fuentes, Alejandro D; Ramos, Pedro L; Sánchez, Yadira; Callard, Danay; Ferreira, Aleines; Tiel, Kenia; Cobas, Karen; Rodríguez, Raisa; Borroto, Carlos; Doreste, Vivian; Pujol, Merardo

    2008-08-01

    Agrobacterium tumefaciens technology is the battle horse for tomato genetic transformation. However, tomato varieties with low regeneration capacity are very difficult to transform. In the past, tomato transformation through Agrobacterium infection was focused on varieties capable of high regeneration yield, while successful transformation of low regenerable cultivars has not been reported. The genotype response to tissue culture conditions is believed to drive the frequency of regeneration of transgenic plant, whereas the capacity for cell proliferation could determine the transformation efficiency through this technology. The Campbell-28 cultivar is an example of constraints arising from a high morphogenetic potential with low conversion compared to normal plants. In the present work the roles that contribute to improved transgenic plant recovery from this recalcitrant variety were explored for factors like Agrobacterium concentration and antibiotics for bacterial removal and transformant selection. Analysis of the efficiency from independent transformation experiments revealed a more than twofold increase of transformant regeneration after selection on ammonium glufosinate compared to kanamycin selection, showing a transformation efficiency of 21.5%.

  18. [Adolescent fertility in the Gambia. Education and declining age at marriage, two limiting factors].

    Science.gov (United States)

    Kane, T T

    1990-08-01

    In Gambia, more than 50% of the population is less than 20 years old. Adolescent fertility comprises 15% of total fertility. It is linked with certain health problems and socioeconomic problems. Adolescent fertility contributes to population growth and can influence socioeconomic development and the level of mortality risks among reproductive age women and their children. In 1983, the total fertility rate for Gambia was 6.4 births per woman compared to 6.5 in 1973. In the urban areas of Banjul and Kombo St. Mary Districts, it was 5.5 and 5.6, respectively. In Gambia overall, women have on average one child during adolescence. In metropolitan Banjul, 61% of all sexually active women and 37% of all sexually active single women had a child during adolescence. 40% of married girls aged 14-15 have been pregnant at least once. Based on the 1983 census, fertility among 15-19 year olds in metropolitan Banjul was 148 births/1000 women. In 1973, it was 199/1000 nationwide. The 1986-1987 fertility survey found their fertility to be 113/1000 based on registered births. Increase of the mean marriage age, higher educational level, and more contraceptive use in metropolitan Banjul may explain the decline in adolescent fertility here. 23% of women aged 15-19 in metropolitan Banjul were married in 1987 compared to 30% in 1983 and 53% for all Gambia in 1987. During 1986-1987, 83% of unschooled 19 year old females in greater Banjul were married compared to 13% of same-aged females with at least 7 years of education. In all of Gambia in 1983, women aged 15-19 with primary education had a fertility rate more than two times greater than that of same-aged women with superior education (220 vs. 103/1000). Adolescent fertility can limit education possibilities and darken economic perspectives. As societies continue to develop and modernize, it will be important to survey adolescent fertility and its socioeconomic and health impact on all youth as well as on the rest of society.

  19. Improving substance information in usetox®, part 2: Data for estimating fate and ecosystem exposure factors

    DEFF Research Database (Denmark)

    Saouter, Erwan; Aschberger, Karin; Fantke, Peter

    2017-01-01

    substance properties, USEtox® quantifies potential human toxicity and freshwater ecotoxicity impacts by combining environmental fate, exposure and toxicity effects information, considering multimedia fate and multi-pathway exposure processes. The main source to obtain substance properties for USEtox® 1....... These regulations require that a chemical risk assessment for humans and the environment is performed before a chemical is placed on the European market. Consequently, additional physicochemical property data and new toxicological end-points are now available for thousands of chemical substances. The aim...... of the present study is to explore to which extent the new available data can be used as input for USEtox® - especially for application in Environmental Footprint studies - and to discuss how this would influence the quantification of fate and exposure factors. Initial results show that the choice of data source...

  20. Concentration factors of radionuclides and trace metals in Mytilus galloprovincialis in an estuarine ecosystem - North Aegean Sea - Greece

    International Nuclear Information System (INIS)

    Florou, H.; Catsiki, A.B.; Papaefthymiou, H.; Chaloulou, Ch.

    2004-01-01

    Mussels are worldwide recognized as pollution bio-indicator organisms (Mussel watch program of CIESM) because they accumulate pollutants in their tissues at elevated levels in terms of biological availability in the marine environment. In the present study, the levels of 137 Cs, Cr, Cu, Mn and Zn were measured in Mytilus galloprovincialis caught from Thermaikos gulf in North Aegean Sea Greece. The samples were collected seasonally from two aqua-cultures during the period 2000 2003. Measured and published concentrations of the above elements in seawater were used for the evaluation of concentration factors by applying a linear and a non-linear regression analysis. The variation in between the two stations and the seasonal evolution of bioaccumulation of the examined elements was also investigated. Some data on the concentrations of the measured elements in sediments from the area considered were evaluated as for determining the pollution conditions of the organism habitat. (author)

  1. [Effect of abiotic and biotic factors on the structural and functional organization of the saline lake ecosystems in Crimea].

    Science.gov (United States)

    Balushkina, E V; Golubkov, S M; Golubkov, M S; Litvinchuk, L F; Shadrin, N V

    2009-01-01

    Decrease of both zooplankton and zoobenthos species richness and a trend toward decrease of their biomass with the salinity increase was recorded in the hypersaline lakes of Crimea. The most of structural and functional characteristics of macrobenthos is positively correlated with abiotic and biotic characteristics of those lakes. Abundance, biomass, productivity of macrobenthos and ration of non-predating macrozoobenthos decrease with salinity increase, while they increase with the depth and growth of amount of chlorophyll a and primary production. Macrozoobenthos portion in the total zooplankton and macrozoobenthos biomass decreases with both salinity and depth increase. Zooplankton community is less controlled by abiotic factors as compared to macrozoobenthos, while the former's species number significantly decrease with salinity increase. Effect of salinity on zooplankton biomass is slightly significant, unlike that of macrozoobenthos. Comparison of total amount of rations of zooplankton and macrozoobenthos with amount of primary production indicates intense trophic interactions in the lakes under study.

  2. Quantitative analysis of risk factors associated with brucellosis in livestock in the Katavi-Rukwa ecosystem, Tanzania.

    Science.gov (United States)

    Assenga, Justine A; Matemba, Lucas E; Malakalinga, Joseph J; Muller, Shabani K; Kazwala, Rudovick R

    2016-02-01

    Brucellosis is a neglected contagious bacterial disease of public health and economic importance. Nevertheless, its spread is not well known to many livestock farmers. Unmatched case control study was carried out to identify risk factors associated with brucellosis in cattle and goats at the herd level in Mpanda, Mlele and Nsimbo districts of Katavi region, in Tanzania between September 2012 and July 2013. A total of 138 adult respondents were selected randomly for the interview using a structured questionnaire. The criterion for inclusion was to have at least one Brucella-positive animal in the herd while the control was chosen from among the herds which these animals tested negative. The presence of seropositive herds were statistically linked (P brucellosis between animals and humans and the implementation of disease prevention and control programmes.

  3. Determination of key environmental factors responsible for distribution patterns of fiddler crabs in a tropical mangrove ecosystem.

    Directory of Open Access Journals (Sweden)

    Mohammad Mokhtari

    Full Text Available In tropical regions, different species of fiddler crabs coexist on the mangrove floor, which sometimes makes it difficult to define species-specific habitat by visual inspection. The aim of this study is to find key environmental parameters which affect the distribution of fiddler crabs and to determine the habitats in which each species was most abundant. Crabs were collected from 19 sites within the mudflats of Sepang-Lukut mangrove forest. Temperature, porewater salinity, organic matter, water content, carbon and nitrogen content, porosity, chlorophyll content, pH, redox potential, sediment texture and heavy metals were determined in each 1 m2 quadrate. Pearson correlation indicated that all sediment properties except pH and redox potential were correlated with sediment grain size. Canonical correspondence analysis (CCA indicated that Uca paradussumieri was negatively correlated with salinity and redox potential. Sand dwelling species, Uca perplexa and Uca annulipes, were highly dependent on the abundance of 250 μm and 150 μm grain size particles in the sediment. Canonical Discriminative Analysis (CDA indicated that variation in sediment grain size best explained where each crab species was most abundant. Moreover, U. paradussumieri commonly occupies muddy substrates of low shore, while U. forcipata lives under the shade of mangrove trees. U. annulipes and U. perplexa with the high number of spoon tipped setae on their second maxiliped are specialized to feed on the sandy sediments. U. rosea and U. triangularis are more common on muddy sediment with high sediment density. In conclusion, sediment grain size that influences most sediment properties acts as a main factor responsible for sediment heterogeneity. In this paper, the correlation between fiddler crab species and environmental parameters, as well as the interaction between sediment characteristics, was explained in order to define the important environmental factors in fiddler crab

  4. Body Weight, Carapace Length and Width Relationship and Condition Factor of the Mud Crab Scylla serrata (Forskal in Mangrove Ecosystem

    Directory of Open Access Journals (Sweden)

    Sarvabhowma Chakravarty MYLA

    2017-09-01

    Full Text Available The relationship of length-weight and width-weight of the carapace and the relative condition factor of mud crab Scylla serrata from Coringa Wildlife Sanctuary (Andhra Pradesh, India was the subject of present study. Significant difference in both males and females was observed between carapace length-weight, carapace width-weight with a linear relationship. The regression values of both the sexes were found to be statistically significant. The regression equations calculated for length-weight were W= 0.00000178 L 3.1139 (r= 0.95 for males, W= 0.00000520 L 2.8056 (r=0.94 for females and for sexes combined it was W = 0.0000297 L 2.9891(r= 0.94. In case of carapace width-weight relationship of males, females and sexes combined the regression equations were W= 0.00000121 CW 3.0426 (r= 0.92, W= 0.00000178 CW 2.775 (r=0.93 and W = 0.00000204 CW 2.9210(r= 0.92 respectively. The male crabs showed positive allometric growth whereas female had negative allometric growth. Analysis of covariance confirmed remarkable difference between males and females in the growth pattern. The mean relative condition factor (Kn values of both males and females and of the pooled sexes ranged from 0.680 (April to 1.029 (November. A gradual raise in Kn values was observed from small- to big- sized crabs in both the sexes. Peak values were observed in 12.0-13.9 cm size group in November.

  5. [Food addiction: Definition, measurement and limits of the concept, associated factors, therapeutic and clinical implications].

    Science.gov (United States)

    Cathelain, Sarah; Brunault, Paul; Ballon, Nicolas; Réveillère, Christian; Courtois, Robert

    2016-12-01

    Addictions, which are characterized by the inability to control a behavior despite existence of physical or psychological consequences, have biological, psychological and social determinants. Although the possibility of developing an addiction to some psychoactive substances (e.g. alcohol, tobacco, cannabis) and to gambling (i.e., gambling disorder) is now well demonstrated, the possibility to develop a non-drug addiction (i.e., behavioral addiction) to certain behaviors which provide pleasure (e.g. eating, having sex, buying things) is still in debate. The concept of food addiction, which refers to people who exhibit substance dependence criteria in relation to some high-fat and high-sugar foods, was recently proposed by applying substance dependence DSM criteria to eating behavior. To assess food addiction, the Yale Food Addiction Scale is now the only self-administered questionnaire (diagnosis and estimate of the number of symptoms of food addiction). Prevalence for food addiction is higher in overweight and obese patients, and in patients with certain psychopathological characteristics (i.e., depression, Attention Deficit Hyperactivity Disorder, high impulsivity), in patients who are single and in patients with neurobiological alterations in the reward system. However, it is still unclear whether food addiction is necessary associated with subsequent increase in body weight and/or obesity. An increasing number of studies demonstrated that drug addiction and food addiction shares some similar clinical, neurobiological and psychopathological and sociocultural risk factors. To test the pertinence to include food addiction as an addiction, it would be interesting to conduct future studies in patients who may experience harms related to their food addiction, including not only patients with obesity, but also patients with metabolic syndrome, type 2 diabetes, hypertension, dyslipidemia, atherosclerosis, stroke, or coronary heart disease. Food addiction is a clinical

  6. Life at the limits: peculiar features of lichen symbiosis related to extreme environmental factors

    Science.gov (United States)

    de Vera, J.-P.; Horneck, G.; Rettberg, P.; Ott, S.

    A lichen is a symbiotic association formed by a mycobiont (fungi), a photobiont (algae) and/or a cyanobacteria. The special symbiotic contact and interaction between the bionts in a lichen is a prerequisite for maintainance of viability for each of them during influences by harsh environmental factors. In nature parameters like UV radiation, low or high temperatures and dryness may have a destructive impact on all life functions of an organism. But with lichens the evolution has created a peculiar symbiosis which enables a wide variety of lichen species to colonize habitats where their separate bionts would not be able to survive. The results of our investigations are demonstrating these aspects (de Vera et al. 2003, 2004).We have already investigated the viability of the entire lichen thallus, the embedded spores in lichen apothecia (fruiting bodies) as well as the isolated spores and isolated photobionts after exposure to most extreme conditions caused by simulated space parameters as extreme UV radiation and vacuum. The results presented here focuse on the survival capacity of the isolated photobionts from the two lichen species Xanthoria elegans and Fulgensia bracteata which are not protected by the fungal structure of the lichen thallus. They are based on examinations using a Confocal Laser Scanning Microscopy (CLSM), analysed by modern methods of the Image Tool Program and by culture experiments. In contrast to photobionts embedded in the entire lichen thallus the isolated photobionts are much more sensitve to the extreme conditions of UV radiation and vaccum: while 50 % of the bionts in an entire lichen thallus are able to cope with simulated extreme space conditions (UV-radiation: λ quad ≥ 160nm and vacuum: p = 10-5 Pa) during an exposure time of 2 weeks, the viability of the isolated photobiont cells was already decreasing after 2 hours of exposure. All photobiont cells were inactivated after longer exposure times of about 8 hours. Further more analysis

  7. Partitioning the impact of environmental factors on lake concentrations and catchment budgets for base cations in forested ecosystems

    International Nuclear Information System (INIS)

    Augustin, Fougère; Houle, Daniel; Gagnon, Christian; Couture, Suzanne; Courchesne, François

    2015-01-01

    Highlights: • We examine base cation budgets (BC Q ) and concentrations (BC C ) in forested catchments. • Climate is the most important driver of BC Q and BC C in the study area. • We develop multivariate models that explain up to 69% of variation in BC C and BC Q . - Abstract: Seventy-two forested lake catchments were studied in Quebec (Canada) to examine the influence of climate, atmospheric deposition and catchment characteristics on base cation (BC) concentrations in lake waters (BC C ) and base cation budgets at the catchment scale (BC Q ). The catchments are located along a bioclimatic gradient in a vast (180 000 km 2 ) study area underlained by the Canadian Shield. Multivariate statistical approaches are used to simultaneously assess the effects of multiple environmental factors on cation fluxes. Mean annual BC C were 132, 40, 24 and 7 μmol c l −1 for Ca, Mg, Na and K, respectively. Mean annual BC Q estimates showed exports of 0.826, 0.251, 0.135 and 0.043 kmol c ha −1 an −1 for Ca, Mg, Na and K, respectively. There were strong similarities in the spatial variation of BC C and BC Q , and also in their links with environmental factors. We hypothesized that the spatial variability of both, BC C and BC Q , were strongly influenced by the spatial variability in the rates of mineral weathering reactions. Variance partitioning indicated that climate-related effects accounted for 51.6% and 52.7% of the variation in BC Q and BC C , respectively. Nonetheless, lake/catchment morphometry and variables linked to solutes sources (lithology, atmospheric deposition and soil properties) were also included in some models. Overall, BC C and BC Q were positively affected by temperature, precipitation as rain and sulphate depositions, and negatively influenced by precipitation as snow and the number of frost days. Multivariate models explaining up to 69% of variation in BC C and BC Q were developed. This study shows the strong impact of climatic drivers on base

  8. Ecosystem services and livelihoods in deltaic environments

    Science.gov (United States)

    Nicholls, R. J.; Rahman, M. M.; Salehin, M.; Hutton, C.

    2015-12-01

    While overall, deltas account for only 1% of global land area, they are home to more than a half billion people or ca. 7% of the world's population. In many deltas, livelihoods and food security are strongly dependent on ecosystem services, which in turn are affected by various environmental change factors, including climate variability and change, modifications to upstream river, sediment and nutrient fluxes, evolving nearshore ecosystems, and delta-level change factors such as subsidence, changing land use and management interventions such as polders. Key limits include scarcity of fresh water, saline water intrusion and the impacts of extreme events (e.g. river floods, cyclones and storm surges), which constrain land use choices and livelihood opportunities for the deltaic populations. The ESPA Deltas project takes a systemic perspective of the interaction between the coupled bio-physical environment and the livelihoods of rural delta residents. The methods emphasise poverty reduction and use coastal Bangladesh as an example. This includes a set of consistent biophysical analyses of the delta and the upstream catchments and the downstream Bay of Bengal, as well as governance and policy analysis and socio-demographic analysis, including an innovative household survey on ecosystem utilization. These results are encapsulated in an integrated model that analyses ecosystem services and livelihood implications. This integrated approach is designed to support delta-level policy formulation. It allows the exploration of contrasting development trajectories, including issues such as robustness of different governance options on ecosystem services and livelihoods. The method is strongly participatory including an ongoing series of stakeholder workshops addressing issue identification, scenario development and consideration of policy responses. The methods presented are generic and transferable to other deltas. The paper will consider the overall ESPA Deltas project and

  9. A Limiting Factor for the Progress of Radionuclide-based Cancer Diagnostics and Therapy - Availability of Suitable Radionuclides

    International Nuclear Information System (INIS)

    Tolmachev, Vladimir; Carlsson, Joergen; Lundqvist, Hans

    2004-01-01

    Advances in diagnostics and targeted radionuclide therapy of haematological and neuroendocrine tumours have raised hope for improved radionuclide therapy of other forms of disseminated tumours. New molecular target structures are characterized and this stimulates the efforts to develop new radiolabelled targeting agents. There is also improved understanding of factors of importance for choice of appropriate radionuclides. The choice is determined by physical, chemical, biological, and economic factors, such as a character of emitted radiation, physical half-life, labelling chemistry, chemical stability of the label, intracellular retention time, and fate of radiocatabolites and availability of the radionuclide. There is actually limited availability of suitable radionuclides and this is a limiting factor for further progress in the field and this is the focus in this article. The probably most promising therapeutic radionuclide, 211 At, requires regional production and distribution centres with dedicated cyclotrons. Such centres are, with a few exceptions in the world, lacking today. They can be designed to also produce beta- and Augeremitters of therapeutic interest. Furthermore, emerging satellite PET scanners will in the near future demand long-lived positron emitters for diagnostics with macromolecular radiopharmaceuticals, and these can also be produced at such centres. To secure continued development and to meet the foreseen requirements for radionuclide availability from the medical community it is necessary to establish specialized cyclotron centres for radionuclide production

  10. Setting limits: The development and use of factor-ceiling distributions for an urban assessment using macroinvertebrates

    Science.gov (United States)

    Carter, J.L.; Fend, S.V.

    2005-01-01

    Lotic habitats in urban settings are often more modified than in other anthropogenically influenced areas. The extent, degree, and permanency of these modifications compromise the use of traditional reference-based study designs to evaluate the level of lotic impairment and establish restoration goals. Directly relating biological responses to the combined effects of urbanization is further complicated by the nonlinear response often observed in common metrics (e.g., Ephemeroptera, Plecoptera, and Trichoptera [EPT] species richness) to measures of human influence (e.g., percentage urban land cover). A characteristic polygonal biological response often arises from the presence of a generalized limiting factor (i.e., urban land use) plus the influence of multiple additional stressors that are nonuniformly distributed throughout the urban environment. Benthic macroinvertebrates, on-site physical habitat and chemistry, and geographical information systems-derived land cover data for 85 sites were collected within the 1,600-km2 Santa Clara Valley (SCV), California urban area. A biological indicator value was derived from EPT richness and percentage EPT. Partitioned regression was used to define reference conditions and estimate the degree of site impairment. We propose that an upper-boundary condition (factor-ceiling) modeled by partitioned regression using ordinary least squares represents an attainable upper limit for biological condition in the SCV area. Indicator values greater than the factor-ceiling, which is monotonically related to existing land use, are considered representative of reference conditions under the current habitat conditions imposed by existing land cover and land use.

  11. Older Asian Americans and Pacific Islanders with Activities of Daily Living (ADL) limitations: immigration and other factors associated with institutionalization.

    Science.gov (United States)

    Fuller-Thomson, Esme; Chi, Monica

    2012-09-07

    This study determined the national prevalence and profile of Asian Americans with Activities of Daily Living (ADL) limitations and identified factors associated with institutionalization. Data were obtained from 2006 American Community Survey, which replaced the long-form of the US Census. The data are nationally representative of both institutionalized and community-dwelling older adults. Respondents were Vietnamese (n = 203), Korean (n = 131), Japanese (n = 193), Filipino (n = 309), Asian Indian (n = 169), Chinese (n = 404), Hawaiian/Pacific Islander (n = 54), and non-Hispanic whites (n = 55,040) aged 55 and over who all had ADL limitations. The prevalence of institutionalized among those with ADL limitations varies substantially from 4.7% of Asian Indians to 18.8% of Korean Americans with ADL limitations. Every AAPI group had a lower prevalence of institutionalization than disabled Non-Hispanic whites older adults (23.8%) (p institutionalization than non-Hispanic whites (OR = 0.29, 0.31, 0.58, 0.51, 0.70, respectively). When the sample was restricted to AAPIs, the odds of institutionalization were higher among those who were older, unmarried, cognitively impaired and those who spoke English at home. This variation suggests that aggregating data across the AAPI groups obscures meaningful differences among these subpopulations and substantial inter-group differences may have important implications in the long-term care setting.

  12. Linkages between benthic assemblages and physical environmental factors: The role of geodiversity in Eastern Gulf of Finland ecosystems

    Science.gov (United States)

    Kaskela, A. M.; Rousi, H.; Ronkainen, M.; Orlova, M.; Babin, A.; Gogoberidze, G.; Kostamo, K.; Kotilainen, A. T.; Neevin, I.; Ryabchuk, D.; Sergeev, A.; Zhamoida, V.

    2017-06-01

    variables. The benthic marine landscapes found in topographically complex seabed areas possessed higher species diversity than flatter areas with fewer seabed features. Our results indicate that on broad spatial scales, geodiversity and archipelago gradient directly influence benthic assemblages by providing a range of different habitats. These factors also indirectly influence benthic assemblages by channeling water movement and thereby distributing hydrologic conditions. This study demonstrates that broad-scale geodiversity should be considered in regional and mesoscale habitat mapping, maritime spatial planning and conservation policies.

  13. Maternal health interventions in resource limited countries: a systematic review of packages, impacts and factors for change

    Science.gov (United States)

    2011-01-01

    Background The burden of maternal mortality in resource limited countries is still huge despite being at the top of the global public health agenda for over the last 20 years. We systematically reviewed the impacts of interventions on maternal health and factors for change in these countries. Methods A systematic review was carried out using the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Articles published in the English language reporting on implementation of interventions, their impacts and underlying factors for maternal health in resource limited countries in the past 23 years were searched from PubMed, Popline, African Index Medicus, internet sources including reproductive health gateway and Google, hand-searching, reference lists and grey literature. Results Out of a total of 5084 articles resulting from the search only 58 qualified for systematic review. Programs integrating multiple interventions were more likely to have significant positive impacts on maternal outcomes. Training in emergency obstetric care (EmOC), placement of care providers, refurbishment of existing health facility infrastructure and improved supply of drugs, consumables and equipment for obstetric care were the most frequent interventions integrated in 52% - 65% of all 54 reviewed programs. Statistically significant reduction of maternal mortality ratio and case fatality rate were reported in 55% and 40% of the programs respectively. Births in EmOC facilities and caesarean section rates increased significantly in 71% - 75% of programs using these indicators. Insufficient implementation of evidence-based interventions in resources limited countries was closely linked to a lack of national resources, leadership skills and end-users factors. Conclusions This article presents a list of evidenced-based packages of interventions for maternal health, their impacts and factors for change in resource limited countries. It indicates that no single

  14. Maternal health interventions in resource limited countries: a systematic review of packages, impacts and factors for change

    Directory of Open Access Journals (Sweden)

    Urassa David P

    2011-04-01

    Full Text Available Abstract Background The burden of maternal mortality in resource limited countries is still huge despite being at the top of the global public health agenda for over the last 20 years. We systematically reviewed the impacts of interventions on maternal health and factors for change in these countries. Methods A systematic review was carried out using the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA. Articles published in the English language reporting on implementation of interventions, their impacts and underlying factors for maternal health in resource limited countries in the past 23 years were searched from PubMed, Popline, African Index Medicus, internet sources including reproductive health gateway and Google, hand-searching, reference lists and grey literature. Results Out of a total of 5084 articles resulting from the search only 58 qualified for systematic review. Programs integrating multiple interventions were more likely to have significant positive impacts on maternal outcomes. Training in emergency obstetric care (EmOC, placement of care providers, refurbishment of existing health facility infrastructure and improved supply of drugs, consumables and equipment for obstetric care were the most frequent interventions integrated in 52% - 65% of all 54 reviewed programs. Statistically significant reduction of maternal mortality ratio and case fatality rate were reported in 55% and 40% of the programs respectively. Births in EmOC facilities and caesarean section rates increased significantly in 71% - 75% of programs using these indicators. Insufficient implementation of evidence-based interventions in resources limited countries was closely linked to a lack of national resources, leadership skills and end-users factors. Conclusions This article presents a list of evidenced-based packages of interventions for maternal health, their impacts and factors for change in resource limited countries

  15. Risk and Resilience Factors Related to Parental Bereavement Following the Death of a Child with a Life-Limiting Condition

    Directory of Open Access Journals (Sweden)

    Tiina Jaaniste

    2017-11-01

    Full Text Available This paper reviews the theoretical and empirical literature on risk and resilience factors impacting on parental bereavement outcomes following the death of a child with a life-limiting condition. Over the past few decades, bereavement research has focussed primarily on a risk-based approach. In light of advances in the literature on resilience, the authors propose a Risk and Resilience Model of Parental Bereavement, thus endeavouring to give more holistic consideration to a range of potential influences on parental bereavement outcomes. The literature will be reviewed with regard to the role of: (i loss-oriented stressors (e.g., circumstances surrounding the death and multiple losses; (ii inter-personal factors (e.g., marital factors, social support, and religious practices; (iii intra-personal factors (e.g., neuroticism, trait optimism, psychological flexibility, attachment style, and gender; and (iv coping and appraisal, on parental bereavement outcomes. Challenges facing this area of research are discussed, and research and clinical implications considered.

  16. An empirical study to determine factors that motivate and limit the implementation of ICT in healthcare environments.

    Science.gov (United States)

    Gururajan, Raj; Hafeez-Baig, Abdul

    2014-12-23

    The maturity and usage of wireless technology has influenced health services, and this has raised expectations from users that healthcare services will become more affordable due to technology growth. There is increasing evidence to justify this expectation, as telehealth is becoming more and more prevalent in many countries. Thus, health services are now offered beyond the boundaries of traditional hospitals, giving rise to many external factors dictating their quality. This has led us to investigate the factors that motivate and limit the implementation of ICT applications in the healthcare domain. We used a mixed method approach with the qualitative aspects leading the quantitative aspects. The main reason for this approach was to understand and explore the domain through the qualitative aspects as we could be part of the discussion. Then we conducted a quantitative survey to extract more responses in order to justify the claims explored in the qualitative process. We found that there are a number of internal and external factors influencing ICT adoption in the healthcare environment so that services can be provided via ICT tools. These factors were grouped under factors contributing to improved outcomes, efficiency and the management of technology. We conceptualised that these three groups of factors drive ICT implementation to assure health services. The main lesson learned from this research was that Information Systems discipline needs to urgently consider health informatics as a serious growth area. We also found that as IS researchers, we need to 'mix' with the health environment in order to understand the environment and then develop suitable methods to answer posited research questions.

  17. Older Asian Americans and Pacific Islanders with Activities of Daily Living (ADL Limitations: Immigration and Other Factors Associated with Institutionalization

    Directory of Open Access Journals (Sweden)

    Esme Fuller-Thomson

    2012-09-01

    Full Text Available This study determined the national prevalence and profile of Asian Americans with Activities of Daily Living (ADL limitations and identified factors associated with institutionalization. Data were obtained from 2006 American Community Survey, which replaced the long-form of the US Census. The data are nationally representative of both institutionalized and community-dwelling older adults. Respondents were Vietnamese (n = 203, Korean (n = 131, Japanese (n = 193, Filipino (n = 309, Asian Indian (n = 169, Chinese (n = 404, Hawaiian/Pacific Islander (n = 54, and non-Hispanic whites (n = 55,040 aged 55 and over who all had ADL limitations. The prevalence of institutionalized among those with ADL limitations varies substantially from 4.7% of Asian Indians to 18.8% of Korean Americans with ADL limitations. Every AAPI group had a lower prevalence of institutionalization than disabled Non-Hispanic whites older adults (23.8% (p < 0.001. After adjustment for socio-demographic characteristics, Asian Indians, Vietnamese, Japanese, Filipino, and Chinese had significantly lower odds of institutionalization than non-Hispanic whites (OR = 0.29, 0.31, 0.58, 0.51, 0.70, respectively. When the sample was restricted to AAPIs, the odds of institutionalization were higher among those who were older, unmarried, cognitively impaired and those who spoke English at home. This variation suggests that aggregating data across the AAPI groups obscures meaningful differences among these subpopulations and substantial inter-group differences may have important implications in the long-term care setting.

  18. Analysis of factors which limited the spatial variation of barley yield on the forest-steppe chernozems of Kursk region

    Science.gov (United States)

    Belik, Anton; Vasenev, Ivan; Jablonskikh, Lidia; Bozhko, Svetlana

    2017-04-01

    The crop yield is the most important indicator of the efficiency of agricultural production. It is the function that depends on a large number of groups of independent variables, such as the weather, soil fertility and overall culture agriculture. A huge number of combinations of these factors contribute to the formation of high spatial variety of crop yields within small areas, includes the slope agrolandscapes in Kursk region. Spatial variety of yield leads to a significant reduction in the efficiency of agriculture. In this connection, evaluation and analysis of the factors, which limits the yield of field crops is a very urgent proble in agroecology. The research was conducted in the period of 2003-2004 on a representative field. The typical and leached chernozems with the varying thickness and of erosion degree are dominated in soil cover. At the time of field research studied areas were busy by barley. The reseached soils have an average and increased fertility level. Chernozem typical full-face, and the leached contain an average of 4.5-6% humus, close to neutral pH, favorable values of physico-chemical parameters, medium and high content of nutrients. The eroded chernozems differs agrogenic marked declining in fertility parameters. The diversity of meso- and micro-relief in the fields and soil cover influence to significant spatial variety of fertility. For example the content of nutrients in the soil variation can be up to 5-fold level. High spatial heterogeneity of soils fertility ifluence to barley yield variety. During research on the productivity of the field varied in the range of 20-43 c/ha, and 7-44 c/ha (2004). Analysis of the factors, which limited the yield of barley, showed that the first priorities occupy unregulated characterises: slope angle and the classification of soils (subtype and race of chernozem and the difference in the degree of erosion), which determines the development of erosion processes and redistribution available to plants

  19. Observation of the fundamental Nyquist noise limit in an ultra-high Q-factor cryogenic bulk acoustic wave cavity

    Energy Technology Data Exchange (ETDEWEB)

    Goryachev, Maxim, E-mail: maxim.goryachev@uwa.edu.au; Ivanov, Eugene N.; Tobar, Michael E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Kann, Frank van [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Galliou, Serge [Department of Time and Frequency, FEMTO-ST Institute, ENSMM, 26 Chemin de l' Épitaphe, 25000 Besançon (France)

    2014-10-13

    Thermal Nyquist noise fluctuations of high-Q bulk acoustic wave cavities have been observed at cryogenic temperatures with a DC superconducting quantum interference device amplifier. High Q modes with bandwidths of few tens of milliHz produce thermal fluctuations with a signal-to-noise ratio of up to 23 dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high (Q > 10{sup 8} at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.

  20. Beneficial and limiting factors for return to work following anterior cruciate ligament reconstruction: a retrospective cohort study.

    Science.gov (United States)

    Groot, Judith A M; Jonkers, Freerk J; Kievit, Arthur J; Kuijer, P Paul F M; Hoozemans, Marco J M

    2017-02-01

    Evidence-based advice for return to work (RTW) after anterior cruciate ligament (ACL) reconstruction is not available. Therefore, the objectives of this study were to determine when patients achieve full RTW, and to explore the beneficial and limiting factors for fully RTW after ACL reconstruction. A retrospective cohort study was performed after ACL reconstruction among 185 patients in one hospital. Data from patient files and a questionnaire were used to explore whether patient-, injury-, surgery-, sports-, work- and rehabilitation-related factors are beneficial or limiting for fully RTW after ACL reconstruction, using a backward stepwise logistic regression analysis. Of the 125 (68%) patients that returned the questionnaire, 36 were not part of the working population. Of the remaining 89 patients, 82 patients (92%) had returned fully to work at follow-up. The median time to fully RTW was 78 days. In the final regression model, which explained 29% of the variance, a significant OR of 5.4 (90% CI 2.2-13.1) for RTW > 78 days was observed for patients performing heavy knee-demanding work compared to patients performing light knee-demanding work. In addition, a significant and positive OR (1.6, 90% CI 1.2-1.9) for the number of weeks walking with the aid of crutches for RTW > 78 days was observed in the final model. After ACL reconstruction, 92% of the patients fully return to work at a median time of 78 days. The significant predictors for fully RTW > 78 days are performing heavy knee-demanding work and a longer period of walking aided with crutches after ACL reconstruction.

  1. Adaptive management for ecosystem services.

    Science.gov (United States)

    Birgé, Hannah E; Allen, Craig R; Garmestani, Ahjond S; Pope, Kevin L

    2016-12-01

    Management of natural resources for the production of ecosystem services, which are vital for human well-being, is necessary even when there is uncertainty regarding system response to management action. This uncertainty is the result of incomplete controllability, complex internal feedbacks, and non-linearity that often interferes with desired management outcomes, and insufficient understanding of nature and people. Adaptive management was developed to reduce such uncertainty. We present a framework for the application of adaptive management for ecosystem services that explicitly accounts for cross-scale tradeoffs in the production of ecosystem services. Our framework focuses on identifying key spatiotemporal scales (plot, patch, ecosystem, landscape, and region) that encompass dominant structures and processes in the system, and includes within- and cross-scale dynamics, ecosystem service tradeoffs, and management controllability within and across scales. Resilience theory recognizes that a limited set of ecological processes in a given system regulate ecosystem services, yet our understanding of these processes is poorly understood. If management actions erode or remove these processes, the system may shift into an alternative state unlikely to support the production of desired services. Adaptive management provides a process to assess the underlying within and cross-scale tradeoffs associated with production of ecosystem services while proceeding with management designed to meet the demands of a growing human population. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Brain-derived neurotrophic factor (BDNF) serum basal levels is not affected by power training in mobility-limited older adults

    DEFF Research Database (Denmark)

    Hvid, L. G.; Nielsen, M. K.F.; Simonsen, C.

    2017-01-01

    Brain-derived neurotrophic factor (BDNF) is a potential important factor involved in neuroplasticity, and may be a mediator for eliciting adaptations in neuromuscular function and physical function in older individuals following physical training. As power training taxes the neural system to a very...... not appear to be a major mechanistic factor mediating neuroplasticity in mobility-limited older adults....

  3. Perceptual and Cognitive Factors Imposing "Speed Limits" on Reading Rate: A Study with the Rapid Serial Visual Presentation.

    Science.gov (United States)

    Primativo, Silvia; Spinelli, Donatella; Zoccolotti, Pierluigi; De Luca, Maria; Martelli, Marialuisa

    2016-01-01

    Adults read at high speed, but estimates of their reading rate vary greatly, i.e., from 100 to 1500 words per minute (wpm). This discrepancy is likely due to different recording methods and to the different perceptual and cognitive processes involved in specific test conditions. The present study investigated the origins of these notable differences in RSVP reading rate (RR). In six experiments we investigated the role of many different perceptual and cognitive variables. The presence of a mask caused a steep decline in reading rate, with an estimated masking cost of about 200 wpm. When the decoding process was isolated, RR approached values of 1200 wpm. When the number of stimuli exceeded the short-term memory span, RR decreased to 800 wpm. The semantic context contributed to reading speed only by a factor of 1.4. Finally, eye movements imposed an upper limit on RR (around 300 wpm). Overall, data indicate a speed limit of 300 wpm, which corresponds to the time needed for eye movement execution, i.e., the most time consuming mechanism. Results reconcile differences in reading rates reported by different laboratories and thus provide suggestions for targeting different components of reading rate.

  4. Limited polymorphism in Plasmodium falciparum ookinete surface antigen, von Willebrand factor A domain-related protein from clinical isolates

    Directory of Open Access Journals (Sweden)

    Eisen Damon P

    2006-07-01

    Full Text Available Abstract Background As malaria becomes increasingly drug resistant and more costly to treat, there is increasing urgency to develop effective vaccines. In comparison to other stages of the malaria lifecycle, sexual stage antigens are under less immune selection pressure and hence are likely to have limited antigenic diversity. Methods Clinical isolates from a wide range of geographical regions were collected. Direct sequencing of PCR products was then used to determine the extent of polymorphisms for the novel Plasmodium falciparum sexual stage antigen von Willebrand Factor A domain-related Protein (PfWARP. These isolates were also used to confirm the extent of diversity of sexual stage antigen Pfs28. Results PfWARP was shown to have non-synonymous substitutions at 3 positions and Pfs28 was confirmed to have a single non-synonymous substitution as previously described. Conclusion This study demonstrates the limited antigenic diversity of two prospective P. falciparum sexual stage antigens, PfWARP and Pfs28. This provides further encouragement for the proceeding with vaccine trials based on these antigens.

  5. Limited polymorphism in Plasmodium falciparum ookinete surface antigen, von Willebrand factor A domain-related protein from clinical isolates.

    Science.gov (United States)

    Richards, Jack S; MacDonald, Nicholas J; Eisen, Damon P

    2006-07-05

    As malaria becomes increasingly drug resistant and more costly to treat, there is increasing urgency to develop effective vaccines. In comparison to other stages of the malaria lifecycle, sexual stage antigens are under less immune selection pressure and hence are likely to have limited antigenic diversity. Clinical isolates from a wide range of geographical regions were collected. Direct sequencing of PCR products was then used to determine the extent of polymorphisms for the novel Plasmodium falciparum sexual stage antigen von Willebrand Factor A domain-related Protein (PfWARP). These isolates were also used to confirm the extent of diversity of sexual stage antigen Pfs28. PfWARP was shown to have non-synonymous substitutions at 3 positions and Pfs28 was confirmed to have a single non-synonymous substitution as previously described. This study demonstrates the limited antigenic diversity of two prospective P. falciparum sexual stage antigens, PfWARP and Pfs28. This provides further encouragement for the proceeding with vaccine trials based on these antigens.

  6. Sleep Disordered Breathing in Four Resource-Limited Settings in Peru: Prevalence, Risk Factors, and Association with Chronic Diseases.

    Science.gov (United States)

    Schwartz, Noah G; Rattner, Adi; Schwartz, Alan R; Mokhlesi, Babak; Gilman, Robert H; Bernabe-Ortiz, Antonio; Miranda, J Jaime; Checkley, William

    2015-09-01

    Sleep disordered breathing (SDB) is a highly prevalent condition in high-income countries, with major consequences for cardiopulmonary health, public safety, healthcare utilization, and mortality. However, its prevalence and effect in low- and middle-income countries are less well known. We sought to determine the prevalence, risk factors, and comorbidities of SDB symptoms in four resource-limited settings. Cross-sectional analysis of the CRONICAS Cohort, a population-based age- and sex-stratified sample. Four resource-limited settings in Peru varying in altitude, urbanization, and air pollution. There were 2,682 adults aged 35 to 92 y. Self-reported SDB symptoms (habitual snoring, observed apneas, Epworth Sleepiness Scale), sociodemographics, medical history, anthropometrics, spirometry, blood biomarkers were reported. We found a high prevalence of habitual snoring (30.2%, 95% confidence interval [CI] 28.5-32.0%), observed apneas (20.9%, 95% CI 19.4-22.5%) and excessive daytime sleepiness (18.6%, 95% CI 17.1-20.1%). SDB symptoms varied across sites; prevalence and adjusted odds for habitual snoring were greatest at sea level, whereas those for observed apneas were greatest at high altitude. In multivariable analysis, habitual snoring was associated with older age, male sex, body mass index (BMI), and higher socioeconomic status; observed apneas were associated with BMI; and excessive daytime sleepiness was associated with older age, female sex, and medium socioeconomic status. Adjusted odds of cardiovascular disease, depression, and hypertension and total chronic disease burden increased progressively with the number of SDB symptoms. A threefold increase in the odds of having an additional chronic comorbid disease (adjusted odds ratio 3.57, 95% CI 2.18-5.84) was observed in those with all three versus no SDB symptoms. Sleep disordered breathing symptoms were highly prevalent, varied widely across four resource-limited settings in Peru, and exhibited strong

  7. ECOLOGICAL FACTORS ASSOCIATED WITH THE ESTABLISHMENT OF RUSTIC SPECIES IN DISTURBED ECOSYSTEMS IN THE ATLANTIC FOREST, PIRAÍ, RIO DE JANEIRO STATE – BRAZIL

    Directory of Open Access Journals (Sweden)

    Hiram Feijó Baylão Junior

    2013-08-01

    Full Text Available http://dx.doi.org/10.5902/1980509810542 Disturbed ecosystems do not present original floristic composition. Their soils are depleted, shallow, stony, with low infiltration and present erosion with different levels of Geodynamics. The region has areas of pasture with sparse herbaceous vegetation which is weakened in every rain and fire, covering less ground. The individuals that colonized and settled in these environments were considered rustic species. This study raised and identified by census, the rustic species and their structure in the most degraded part (lower third of the watershed of Cacaria’s river at the base of the Serra do Mar, Piraí, Rio de Janeiro state, and evaluated the influence of ecological exposure, slope, elevation, topography and rock outcrops in the establishment and growth of these species. For the vegetation survey it was conducted census in an area of 22 hectares, where it was measured, geo-referenced and identified all spontaneous tree species that were isolated in a pasture area. Ecological factors exposure, elevation and slope were determined with a compass, altimeter and clinometer, respectively. We identified 131 individuals, representing 14 species, grouped into nine families. Tabernaemontana laeta Mart., Sparattosperma leucanthum (Vell. Schum., Machaerium hirtum (Vell. Stellfeld, Tabebuia chrysotricha (Mart. ex DC. Stan., Cecropia pachystachya Trec., Peltophorum dubium (Spreng. Taub., Guarea guidonia (L. Sleumer, Acacia polyphylla DC. and Psidium guajava L.were present in portions of the slope with exposure to the north, with altitudes from 60m to 80m and with slope strongly corrugated (20-45%, indicating a preference of these species for microhabitats with those characteristics. 

  8. Mycorrhizal fungi reduce nutrient loss from model grassland ecosystems.

    NARCIS (Netherlands)

    van der Heijden, M.G.A.

    2010-01-01

    Nutrient loss from ecosystems is among the top environmental threats to ecosystems worldwide, leading to reduced plant productivity in nutrient-poor ecosystems and eutrophication of surface water near nutrient-rich ecosystems. Hence, it is of pivotal importance to understand which factors influence

  9. DRIVING AND LIMITING FACTORS IN THE FARM MANAGEMENT BY YOUNG FARMERS IN THE CONTEXT OF SURVEY RESEARCH

    Directory of Open Access Journals (Sweden)

    Barbara Kiełbasa

    2016-03-01

    Full Text Available The purpose of the study was to identify driving and limiting factors of farm management in a region of fragmented agriculture. The paper presents the results of the research conducted in the South-Eastern Poland (Macroregion of Małopolska and Pogórze. The survey was conducted in 2014 in the farms managed by young farmers, i.e. the benefi ciaries of the measure “Setting up of young farmers” from the RDP 2007–2013, with the use of a survey method with a questionnaire interview. The research was empirical, and its main goal was to present a case study of the farm management by young farmers in terms of specifi c management barriers. The results of the studies pointed to the fragmented agrarian structure as the one of the biggest barriers of the eff ective farm management. The young farmers pointed that fragmented agrarian structure signifi cantly impedes the purchase or lease of agricultural land, and the farm development in the same way. The survey pointed to the factors that contribute to the young farmers: the entrepreneurial attitude, activity and creativity, training, the management knowledge and better access to the Common Agricultural Policy instruments.

  10. Limited clinical efficacy of azacitidine in transfusion-dependent, growth factor-resistant, low- and Int-1-risk MDS

    DEFF Research Database (Denmark)

    Holm, Mette; Dybedahl, I; Holm, Mette

    2014-01-01

    This prospective phase II study evaluated the efficacy of azacitidine (Aza)+erythropoietin (Epo) in transfusion-dependent patients with lower-risk myelodysplastic syndrome (MDS). Patients ineligible for or refractory to full-dose Epo+granulocyte colony stimulation factors for >8 weeks and a trans......This prospective phase II study evaluated the efficacy of azacitidine (Aza)+erythropoietin (Epo) in transfusion-dependent patients with lower-risk myelodysplastic syndrome (MDS). Patients ineligible for or refractory to full-dose Epo+granulocyte colony stimulation factors for >8 weeks...... after Aza+Epo, giving a total response rate of 20%. Mutational screening revealed a high frequency of recurrent mutations. Although no single mutation predicted for response, SF3A1 (n=3) and DNMT3A (n=4) were only observed in non-responders. We conclude that Aza can induce TI in severely anemic MDS...... patients, but efficacy is limited, toxicity substantial and most responses of short duration. This treatment cannot be generally recommended in lower-risk MDS. Mutational screening revealed a high frequency of mutations....

  11. The Importance of Permafrost Thaw, Fire and Logging Disturbances as Driving Factors of Historical and Projected Carbon Dynamics in Alaskan Ecosystems

    Science.gov (United States)

    Genet, H.; Zhang, Y.; McGuire, A. D.; He, Y.; Johnson, K. D.; D'Amore, D. V.; Zhou, X.; Bennett, A.; Breen, A. L.; Biles, F. E.; Bliss, N. B.; Euskirchen, E. S.; Kurkowski, T. A.; Pastick, N.; Rupp, S. T.; Wylie, B. K.; Zhu, Z.; Zhuang, Q.

    2014-12-01

    Carbon dynamics of natural ecosystems are influenced by disturbance regimes of various frequencies and magnitudes. With global change, these disturbances are projected to increase in frequency and/or magnitude and may have significant effects on future net carbon balance, especially in high latitude ecosystems where carbon stocks are among the largest on Earth and climate change is substantial. In Alaska, permafrost degradation and fire in the boreal and arctic regions and logging in the southern coastal region are the main disturbances that affect ecosystems. Large uncertainties related to the effects of these disturbances on the capacity of these regions to store carbon still exist mainly due to difficulty in representing permafrost degradation in current ecosystem models. We ran the Terrestrial Ecosystem Model (TEM), which explicitly simulates the carbon cycle and permafrost dynamics, coupled with a disturbance model (the Alaska Frame Based Ecosystem Code, ALFRESCO) to assess the relative importance of permafrost thaw, wildfire, and forest management on historical and projected carbon balance and carbon stocks in Alaska, from 1950 to 2100, at a 1-km resolution. Our simulations showed that the increase in plant productivity in response to warming in boreal and arctic regions is offset by soil carbon loss due to permafrost degradation and wildfire combustion during both historical and future simulations. Fire disturbances act as a catalyst accelerating permafrost degradation and associated soil carbon loss. In addition, our preliminary results for south coastal regions of Alaska indicate that logging of second growth forests could influence carbon dynamics in that region. Overall, these results have implications for land management strategies and illustrate the importance of taking into account multiple types of disturbance regimes in ecosystem models for Alaska.

  12. Long-term tolerability of PRRT in 807 patients with neuroendocrine tumours: the value and limitations of clinical factors

    Energy Technology Data Exchange (ETDEWEB)

    Bodei, Lisa; Grana, Chiara M. [European Institute of Oncology, Division of Nuclear Medicine, Milan (Italy); Kidd, Mark; Drozdov, Ignat; Lepensky, Christopher; Modlin, Irvin M. [Yale School of Medicine, Department of Surgery, New Haven, CT (United States); Paganelli, Giovanni [Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Nuclear Medicine and Radiometabolic Units, Meldola (Italy); Cremonesi, Marta [European Institute of Oncology, Division of Medical Physics, Milan (Italy); Kwekkeboom, Dik J.; Krenning, Eric P. [Erasmus Medical Center, Department of Nuclear Medicine, Rotterdam (Netherlands); Baum, Richard P. [Zentralklinik Bad Berka, Theranostics Center for Molecular Radiotheraphy and Molecular Imaging, Bad Berka (Germany)

    2015-01-15

    9 months, p = 0.01) were relevant. Acute leukaemia occurred in 1.1 % of patients (modelled by the clinical data in 18 %, p < 0.0001). Identified risk factors provide a limited (<30 %) risk estimate even with target tissue dosimetry. These data strongly suggest the existence of unidentified individual susceptibilities to radiation-associated disease. (orig.)

  13. Factors limiting regeneration of Quercus alba and Cornus florida in formerly cultivated coastal plain sites, South Carolina.

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Joseph, M., Jr.; Jones, Robert, H.

    2003-01-01

    Riley, J.M. Jr., and R.H.Jones. 2003. Factors limiting regeneration of Quercus alba and Cornus florida in formerly cultivated coastal plain sites, South Carolina. For. Ecol., and Mgt. 177:571-586. To determine the extent that resources, conditions, and herbivoryy limit regeneration of Quercus alba L. and Cornus florida L. in formerly cultivated coastal plain uplands, we planted seedlings of the two species in two pine and one pine-hardwood forest understory and three adjacent clearcuts. Soil carbon and moisture, available nitrogen and phosphorous, and gap light index (GLI) were measured next to each seedling. Over two growing seasons, stem and leaf herbivory were estimated and survival was recorded. At the end of 2 years, all surviving stems were harvested to determine total leaf area and 2-year biomass growth. Survival to the end of the study was not significantly different between clearcuts and understories. However, clearcuts led to significantly greater biomass growth and leaf area for both Q. alba and C. florida. Soil moisture and available nutrients were also greater in the clearcuts. Using separate multiple linear (growth) or logistic (survival) regressions for each combination of three sites, two cutting treatments and two species, we found that soil moisture significantly affected survival in 12.5% and biomass growth in 8.3% of the regressions. Light availability significantly impacted biomass growth in 16.7% of the regressions. Stem and leaf herbivory had very little impact on survival (8.3%), but when combined, these two factors significantly impacted leaf area or biomass growth in 33.3% of the regressions. Seedling responses were highly variable, and no regression model accounted for more that 70.0% of this variation. In our study, stand-scalevariation in seedling responses (especially the difference between clearcut and understory) was much greater than within-stand variation. Of the within stand factors measured, herbivory was clearly the most

  14. Microbial Ecosystems, Protection of

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Nelson, K.E.

    2014-01-01

    Synonyms Conservation of microbial diversity and ecosystem functions provided by microbes; Preservation of microbial diversity and ecosystem functions provided by microbes Definition The use, management, and conservation of ecosystems in order to preserve microbial diversity and functioning.

  15. Eco-Health Linkages: evidence base and socio-economic considerations for linking ecosystem goods and services to human health

    Science.gov (United States)

    Ecosystem goods and services (EGS) are thought to play a role in protecting human health, but the empirical evidence directly linking EGS to human health outcomes is limited, and our ability to detect Eco-Health linkages is confounded by socio-economic factors. These limitations ...

  16. Australian shellfish ecosystems: Past distribution, current status and future direction.

    Science.gov (United States)

    Gillies, Chris L; McLeod, Ian M; Alleway, Heidi K; Cook, Peter; Crawford, Christine; Creighton, Colin; Diggles, Ben; Ford, John; Hamer, Paul; Heller-Wagner, Gideon; Lebrault, Emma; Le Port, Agnès; Russell, Kylie; Sheaves, Marcus; Warnock, Bryn

    2018-01-01

    We review the status of marine shellfish ecosystems formed primarily by bivalves in Australia, including: identifying ecosystem-forming species, assessing their historical and current extent, causes for decline and past and present management. Fourteen species of bivalves were identified as developing complex, three-dimensional reef or bed ecosystems in intertidal and subtidal areas across tropical, subtropical and temperate Australia. A dramatic decline in the extent and condition of Australia's two most common shellfish ecosystems, developed by Saccostrea glomerata and Ostrea angasi oysters, occurred during the mid-1800s to early 1900s in concurrence with extensive harvesting for food and lime production, ecosystem modification, disease outbreaks and a decline in water quality. Out of 118 historical locations containing O. angasi-developed ecosystems, only one location still contains the ecosystem whilst only six locations are known to still contain S. glomerata-developed ecosystems out of 60 historical locations. Ecosystems developed by the introduced oyster Crasostrea gigas are likely to be increasing in extent, whilst data on the remaining 11 ecosystem-forming species are limited, preventing a detailed assessment of their current ecosystem-forming status. Our analysis identifies that current knowledge on extent, physical characteristics, biodiversity and ecosystem services of Australian shellfish ecosystems is extremely limited. Despite the limited information on shellfish ecosystems, a number of restoration projects have recently been initiated across Australia and we propose a number of existing government policies and conservation mechanisms, if enacted, would readily serve to support the future conservation and recovery of Australia's shellfish ecosystems.

  17. Assessment of factors limiting algal growth in acidic pit lakes--a case study from Western Australia, Australia.

    Science.gov (United States)

    Kumar, R Naresh; McCullough, Clint D; Lund, Mark A; Larranaga, Santiago A

    2016-03-01

    Open-cut mining operations can form pit lakes on mine closure. These new water bodies typically have low nutrient concentrations and may have acidic and metal-contaminated waters from acid mine drainage (AMD) causing low algal biomass and algal biodiversity. A preliminary study was carried out on an acidic coal pit lake, Lake Kepwari, in Western Australia to determine which factors limited algal biomass. Water quality was monitored to obtain baseline data. pH ranged between 3.7 and 4.1, and solute concentrations were slightly elevated to levels of brackish water. Concentrations of N were highly relative to natural lakes, although concentrations of FRP (<0.01 mg/L) and C (total C 0.7-3.7 and DOC 0.7-3.5 mg/L) were very low, and as a result, algal growth was also extremely low. Microcosm experiment was conducted to test the hypothesis that nutrient enrichment will be able to stimulate algal growth regardless of water quality. Microcosms of Lake Kepwari water were amended with N, P and C nutrients with and without sediment. Nutrient amendments under microcosm conditions could not show any significant phytoplankton growth but was able to promote benthic algal growth. P amendments without sediment showed a statistically higher mean algal biomass concentration than controls or microcosms amended with phosphorus but with sediment did. Results indicated that algal biomass in acidic pit lake (Lake Kepwari) may be limited primarily by low nutrient concentrations (especially phosphorus) and not by low pH or elevated metal concentrations. Furthermore, sediment processes may also reduce the nutrient availability.

  18. Merging Platform Ecosystems in Technology Acquisitions

    DEFF Research Database (Denmark)

    Dowie, Jamie; Henningsson, Stefan; Kude, Thomas

    2017-01-01

    of the merging companies. Given the increasing importance of platforms and value co-creation with third-party providers for companies making technology acquisitions, we complement existing literature by reframing the analysis of technology acquisitions to include the merger of the broader partner ecosystems....... Specifically, we draw on theories of ecosystem governance to analyze how ecosystem tensions unfolded during the ecosystem merger and how the acquirer governed these tensions in SAP SE’s acquisition of the e-commerce provider Hybris AG. Our findings suggest that the governance of ecosystem tensions...... is an important aspect of managing technology acquisitions. We identify the pre-acquisition relation between the acquired company’s ecosystem partners and the acquirer as an important context factor for explaining how a partner company is exposed to the ecosystem tensions during the merger....

  19. Multicistronic lentiviral vectors containing the FMDV 2A cleavage factor demonstrate robust expression of encoded genes at limiting MOI

    Directory of Open Access Journals (Sweden)

    Margison Geoffrey P

    2006-03-01

    Full Text Available Abstract Background A number of gene therapy applications would benefit from vectors capable of expressing multiple genes. In this study we explored the feasibility and efficiency of expressing two or three transgenes in HIV-1 based lentiviral vector. Bicistronic and tricistronic self-inactivating lentiviral vectors were constructed employing the internal ribosomal entry site (IRES sequence of encephalomyocarditis virus (EMCV and/or foot-and-mouth disease virus (FMDV cleavage factor 2A. We employed enhanced green fluorescent protein (eGFP, O6-methylguanine-DNA-methyltransferase (MGMT, and homeobox transcription factor HOXB4 as model genes and their expression was detected by appropriate methods including fluorescence microscopy, flow cytometry, immunocytochemistry, biochemical assay, and western blotting. Results All the multigene vectors produced high titer virus and were able to simultaneously express two or three transgenes in transduced cells. However, the level of expression of individual transgenes varied depending on: the transgene itself; its position within the construct; the total number of transgenes expressed; the strategy used for multigene expression and the average copy number of pro-viral insertions. Notably, at limiting MOI, the expression of eGFP in a bicistronic vector based on 2A was ~4 times greater than that of an IRES based vector. Conclusion The small and efficient 2A sequence can be used alone or in combination with an IRES for the construction of multicistronic lentiviral vectors which can express encoded transgenes at functionally relevant levels in cells containing an average of one pro-viral insert.

  20. Prevalence and Risk Factors Associated with Precancerous Cervical Cancer Lesions among HIV-Infected Women in Resource-Limited Settings

    Directory of Open Access Journals (Sweden)

    Peter Memiah

    2012-01-01

    Full Text Available Objective. To assess the prevalence and identified associated risk factors for precancerous cervical cancer lesions among HIV-infected women in resource-limited settings in Kenya. Methods. HIV-infected women attending the ART clinic at the Nazareth Hospital ART clinic between June 2009 and September 2010. Multivariate logistic regression model with odds ratios and 95% confidence intervals (CI were estimated after controlling for important covariates. Result. A total of 715 women were screened for cervical cancer. The median age of the participants was 40 years (range 18–69 years. The prevalence of precancerous lesions (CINI, CINII, CIN III, ICC was 191 (26.7%. After controlling for other variables in logistic regression analysis, cervical precancerous lesions were associated with not being on ART therapy; whereby non-ART were 2.21 times more likely to have precancerous lesions than ART patients [(aOR=2.21, 95% CI (1.28–3.83]. Conclusion. The prevalence of precancerous cervical lesions was lower than other similar settings. It is recommended that cancer screening of HIV-infected women should be an established practice. Availability and accessibility of these services can be done through their integration into HIV. Prompt initiation of HAART through an early enrollment into care has an impact on reducing the prevalence and progression of cervical precancerous lesions.

  1. Carbon baseline as limiting factor in managing environmental sound activities in peatland for reducing greenhouse gas emission

    Directory of Open Access Journals (Sweden)

    BAMBANG HERO SAHARJO

    2011-07-01

    Full Text Available Saharjo BH (2011 Carbon baseline as limiting factor in managing environmental sound activities in peatland for reducing greenhouse gas emission. Biodiversitas 12: 182-186. The total carbon stock in Indonesia was estimated to be around 44.5 Gt or about 53.1% of the total carbon stock in tropical areas. Over 1990-2002, it was estimated that around 3.5 Gt of carbon was released in Sumatra and about 0.81-2.56 Gt was released in Central Kalimantan due to the 1997 fire alone. It was recognized that deforestation, high exploitation of peat and peat fire were behind the huge emissions of Greenhouse Gases in Indonesia. Results of a research conducted in Central Kalimantan peatland, showed that the total carbon stock at logged over area was estimated around 413.972 t ha-1 (0-30 cm depth of peat and at burnt area was 411.349 t ha-1 (0-30 cm depth of peat. Meanwhile it had been well recognized that most of opened peatlands had been occupied by Acacia crassicarpa and oil palms. Research carried out in East Kalimantan showed that the carbon stock of 25 years old oil palm planted on mineral soil was about 180 t ha-1, which is less than that of carbon stock produced by peatland clearance. This indicated that although plants occupied peatland, high Greenhouse Gas emissions were still produced, meaning that global climate change would continue and created high risk impacts.

  2. Uncovering ecosystem service bundles through social preferences.

    Directory of Open Access Journals (Sweden)

    Berta Martín-López

    Full Text Available Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem's capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem's capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis. We found a clear trade-off among provisioning services (and recreational hunting versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs.

  3. Uncovering ecosystem service bundles through social preferences.

    Science.gov (United States)

    Martín-López, Berta; Iniesta-Arandia, Irene; García-Llorente, Marina; Palomo, Ignacio; Casado-Arzuaga, Izaskun; Amo, David García Del; Gómez-Baggethun, Erik; Oteros-Rozas, Elisa; Palacios-Agundez, Igone; Willaarts, Bárbara; González, José A; Santos-Martín, Fernando; Onaindia, Miren; López-Santiago, Cesar; Montes, Carlos

    2012-01-01

    Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem's capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem's capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area) have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis). We found a clear trade-off among provisioning services (and recreational hunting) versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs.

  4. [Participation limitations following acquired brain damage: a pilot study on the relationship among functional disorders as well as personal and environmental context factors].

    Science.gov (United States)

    Fries, W; Fischer, S

    2008-10-01

    The SGB IX, book 9 of the German social code (Sozialgesetzbuch, SGB), which is the legal basis of rehabilitation in Germany, states "participation and self-determined conduct of life" as the ultimate ambition of rehabilitation. This concept of participation and disability is based on the WHO model expressed in the International Classification of Functioning, Disability and Health (ICF). In this model, participation after the onset of a health problem may not only be infringed by disturbances in body functions and structures and the resulting activity limitations but also by contextual factors such as environmental and personal factors. In an outpatient neurological rehabilitation centre we prospectively rated for 49 patients the influence of these contextual factors as well as of objectively assessed functional/activity limitations on the overall disability. On average, functional/activity limitations were rated as contributing 58.4% (SD=17.2%), personal factors 26.4% (SD=12.7%) and environmental factors 15.1% (SD=11.2%) to the overall disability. The functional/activity limitations closely matched the expected limitations based on the underlying brain lesions. The degree of disability based on contextual factors was not related to activity limitations based on disturbances of body functions and structures. Also, demographic variables such as age, sex or chronicity were not significantly linked to contextual factors. Since contextual factors together contributed 41.6% (SD=17.2%) to the overall disability they have major relevance for the rehabilitation process, because they essentially decide on the extent to which abilities acquired by the rehabilitant during rehabilitation actually be transfered to his everyday life. Therefore, rehabilitation programmes need to include assessment and treatment of contextual factors. It hence is necessary to develop instruments to quantify contextual factors.

  5. The influence of neighbourhood socio-demographic factors on densities of free-roaming cat populations in an urban ecosystem in Israel

    NARCIS (Netherlands)

    Finkler, H.; Hatna, E.; Terkel, J.

    2011-01-01

    Free-roaming cat populations are abundant in many urban ecosystems worldwide. Their management is necessary for reasons of public health, risk of wildlife predation and cat welfare related to their high densities. Trap-neuter-return (TNR) programs are now the main cat population control strategy in

  6. Linking community and ecosystem dynamics through spatial ecology.

    Science.gov (United States)

    Massol, François; Gravel, Dominique; Mouquet, Nicolas; Cadotte, Marc W; Fukami, Tadashi; Leibold, Mathew A

    2011-03-01

    Classical approaches to food webs focus on patterns and processes occurring at the community level rather than at the broader ecosystem scale, and often ignore spatial aspects of the dynamics. However, recent research suggests that spatial processes influence both food web and ecosystem dynamics, and has led to the idea of 'metaecosystems'. However, these processes have been tackled separately by 'food web metacommunity' ecology, which focuses on the movement of traits, and 'landscape ecosystem' ecology, which focuses on the movement of materials among ecosystems. Here, we argue that this conceptual gap must be bridged to fully understand ecosystem dynamics because many natural cases demonstrate the existence of interactions between the movements of traits and materials. This unification of concepts can be achieved under the metaecosystem framework, and we present two models that highlight how this framework yields novel insights. We then discuss patches, limiting factors and spatial explicitness as key issues to advance metaecosystem theory. We point out future avenues for research on metaecosystem theory and their potential for application to biological conservation. © 2011 Blackwell Publishing Ltd/CNRS.

  7. Tenax extraction for exploring rate-limiting factors in methyl-β-cyclodextrin enhanced anaerobic biodegradation of PAHs under denitrifying conditions in a red paddy soil

    International Nuclear Information System (INIS)

    Sun, Mingming; Ye, Mao; Hu, Feng; Li, Huixin; Teng, Ying; Luo, Yongming; Jiang, Xin; Kengara, Fredrick Orori

    2014-01-01

    Highlights: • Enhanced anaerobic bioremediation of a red paddy soil polluted with PAHs. • 1% (w/w) methyl-β-cyclodextrin (MCD) and 20 mM nitrate addition acted as solubility-enhancing agent and electron acceptor respectively. • Tenax extraction and a first-three-compartment modeling were applicable to explore the rate-limiting factors in the biodegradation. • Lack of PAH-degraders hindered biodegradation in control and MCD addition treatments. • Inadequate bioaccessible PAHs was vital rate-limiting factor in nitrate addition treatments. -- Abstract: The effectiveness of anaerobic bioremediation systems for PAH-contaminated soil may be constrained by low contaminants bioaccessibility due to limited aqueous solubility and lack of suitable electron acceptors. Information on what is the rate-limiting factor in bioremediation process is of vital importance in the decision in what measures can be taken to assist the biodegradation efficacy. In the present study, four different microcosms were set to study the effect of methyl-β-cyclodextrin (MCD) and nitrate addition (N) on PAHs biodegradation under anaerobic conditions in a red paddy soil. Meanwhile, sequential Tenax extraction combined with a first-three-compartment model was employed to evaluate the rate-limiting factors in MCD enhanced anaerobic biodegradation of PAHs. Microcosms with both 1% (w/w) MCD and 20 mM N addition produced maximum biodegradation of total PAHs of up to 61.7%. It appears rate-limiting factors vary with microcosms: low activity of degrading microorganisms is the vital rate-limiting factor for control and MCD addition treatments (CK and M treatments); and lack of bioaccessible PAHs is the main rate-limiting factor for nitrate addition treatments (N and MN treatments). These results have practical implications for site risk assessment and cleanup strategies

  8. Social-ecological drivers of multiple ecosystem services: what variables explain patterns of ecosystem services across the Norrström drainage basin?

    Directory of Open Access Journals (Sweden)

    Megan Meacham

    2016-03-01

    Full Text Available In human dominated landscapes many diverse, and often antagonistic, human activities are intentionally and inadvertently determining the supply of various ecosystem services. Understanding how different social and ecological factors shape the availability of ecosystem services is essential for fair and effective policy and management. In this paper, we evaluate how well alternative social-ecological models of human impact on ecosystems explain patterns of 16 ecosystem services (ES across the 62 municipalities of the Norrström drainage basin in Sweden. We test four models of human impact on ecosystems, land use, ecological modernization, ecological footprint, and location theory, and test their ability to predict both individual ES and bundles of ES. We find that different models do best to predict different types of individual ES. Land use is the best model for predicting provisioning services, standing water quality, biodiversity appreciation, and cross-country skiing, while other models work better for the remaining services. However, this range of models is not able to predict some of the cultural ES. ES bundles are predicted worse than individual ES by these models, but provide a clear picture of variation in multiple ecosystem services based on limited information. Based on our results, we offer suggestions on how social-ecological modeling and assessments of ecosystems can be further developed.

  9. The course of limitations in activities in patients with knee and hip osteoarthritis: risk factors for future functional decline.

    NARCIS (Netherlands)

    Pisters, M.F.; Veenhof, C.; Dijk, G.M. van; Heymans, M.W.; Twisk, J.W.R.; Dekker, J.

    2011-01-01

    Purpose: To describe the course of limitations in activities over five years follow-up and identify predictors of future limitations in activities in elderly patients with osteoarthritis (OA) of the hip or knee. Relevance: Although cross sectional research on determinants of limitations in

  10. Terrestrial ecosystems under warmer and drier climates

    Science.gov (United States)

    Pan, Y.

    2016-12-01

    Future warmer and drier climates will likely affect many of the world's terrestrial ecosystems. These changes will fundamentally reshape terrestrial systems through their components and across organization levels. However, it is unclear to what extent terrestrial ecosystems would be resilient enough to stay put to increased temperature and water stress by only adjusting carbon fluxes and water balances? And to what extent it would reach the thresholds at which terrestrial ecosystems were forced to alter species compositions and ecosystem structures for adapting to newer climates? The energy balance of terrestrial ecosystems link thermal and water conditions to defines terrestrial carbon processes and feedbacks to climate, which will inevitably change under warmer and drier climates. Recent theoretical studies provide a new framework, suggesting that terrestrial ecosystems were capable of balancing costs of carbon gain and water transport to achieve optimums for functioning and distribution. Such a paradigm is critical for understanding the dynamics of future terrestrial ecosystems under climate changes, and facilitate modeling terrestrial ecosystems which needs generalized principles for formulating ecosystem behaviors. This study aims to review some recent studies that explore responses of terrestrial ecosystems to rather novel climate conditions, such as heat-induced droughts, intending to provide better comprehension of complex carbon-water interactions through plants to an ecosystem, and relevant factors that may alleviate or worsen already deteriorated climates such as elevated CO2 and soil conditions.

  11. The contribution of ecosystem services to place utility as a determinant of migration decision-making

    International Nuclear Information System (INIS)

    Adams, Helen; Neil Adger, W

    2013-01-01

    Environment migration research has sought to provide an account of how environmental risks and resources affect migration and mobility. Part of that effort has focused on the role of the environment in providing secure livelihoods through provisioning ecosystem services. However, many of the models of environment migration linkages fail to acknowledge the importance of social and psychological factors in the decision to migrate. Here, we seek to provide a more comprehensive model of migration decision-making under environmental change by investigating the attachment people form to place, and the role of the environment in creating that attachment. We hypothesize that environmental factors enter the migration decision-making process through their contribution to place utility, defined as a function of both affective and instrumental bonds to location, and that ecosystem services, the aspects of ecosystems that create wellbeing, contribute to both components of place utility. We test these ideas in four rural highland settlements in Peru sampled along an altitudinal gradient. We find that non-economic ecosystem services are important in creating place attachment and that ecological place attachment exists independently of use of provisioning ecosystem services. Individuals’ attitudes to ecosystem services vary with the type of ecosystem services available at a location and the degree of rurality. While social and economic factors are the dominant drivers of migration in these locations, a loss of non-provisioning ecosystem services leads to a decrease in place utility and commitment to place, determining factors in the decision to migrate. The findings suggest that policy interventions encouraging migration as an adaptation to environmental change will have limited success if they only focus on provisioning services. A much wider set of individuals will experience a decrease in place utility, and migration will be unable to alleviate that decrease since the factors

  12. The contribution of ecosystem services to place utility as a determinant of migration decision-making

    Science.gov (United States)

    Adams, Helen; Adger, W. Neil

    2013-03-01

    Environment migration research has sought to provide an account of how environmental risks and resources affect migration and mobility. Part of that effort has focused on the role of the environment in providing secure livelihoods through provisioning ecosystem services. However, many of the models of environment migration linkages fail to acknowledge the importance of social and psychological factors in the decision to migrate. Here, we seek to provide a more comprehensive model of migration decision-making under environmental change by investigating the attachment people form to place, and the role of the environment in creating that attachment. We hypothesize that environmental factors enter the migration decision-making process through their contribution to place utility, defined as a function of both affective and instrumental bonds to location, and that ecosystem services, the aspects of ecosystems that create wellbeing, contribute to both components of place utility. We test these ideas in four rural highland settlements in Peru sampled along an altitudinal gradient. We find that non-economic ecosystem services are important in creating place attachment and that ecological place attachment exists independently of use of provisioning ecosystem services. Individuals’ attitudes to ecosystem services vary with the type of ecosystem services available at a location and the degree of rurality. While social and economic factors are the dominant drivers of migration in these locations, a loss of non-provisioning ecosystem services leads to a decrease in place utility and commitment to place, determining factors in the decision to migrate. The findings suggest that policy interventions encouraging migration as an adaptation to environmental change will have limited success if they only focus on provisioning services. A much wider set of individuals will experience a decrease in place utility, and migration will be unable to alleviate that decrease since the factors

  13. Limit of detection and threshold for positivity of the Centers for Disease Control and Prevention assay for factor VIII inhibitors.

    Science.gov (United States)

    Miller, C H; Boylan, B; Shapiro, A D; Lentz, S R; Wicklund, B M

    2017-10-01

    Essentials Immunologic methods detect factor VIII (FVIII) antibodies in some inhibitor-negative specimens. Specimens were tested by modified Nijmegen-Bethesda assay (NBA) and fluorescence immunoassay. The NBA with preanalytical heat inactivation detects FVIII inhibitors down to 0.2 NBU. IgG 4 frequency validates the established threshold for positivity of ≥ 0.5 NBU for this NBA. Background The Bethesda assay for measurement of factor VIII inhibitors called for quantification of positive inhibitors by using dilutions producing 25-75% residual activity (RA), corresponding to 0.4-2.0 Bethesda units, with the use of 'more sensitive methods' for samples with RA closer to 100% being recommended. The Nijmegen modification (Nijmegen-Bethesda assay [NBA]) changed the reagents used but not these calculations. Some specimens negative by the NBA have been shown to have FVIII antibodies detectable with sensitive immunologic methods. Objective To examine the performance at very low inhibitor titers of the Centers for Disease Control and Prevention (CDC)-modified NBA (CDC-NBA), which includes preanalytic heat inactivation to liberate bound anti-FVIII antibodies. Methods Specimens with known inhibitors were tested with the CDC-NBA. IgG 4 anti-FVIII antibodies were measured by fluorescence immunoassay (FLI). Results Diluted inhibitors showed linearity below 0.4 Nijmegen-Bethesda units (NBU). With four statistical methods, the limit of detection of the CDC-NBA was determined to be 0.2 NBU. IgG 4 anti-FVIII antibodies, which correlate most strongly with functional inhibitors, were present at rates above the background rate of healthy controls in specimens with titers ≥ 0.2 NBU and showed an increase in frequency from 14.3% at 0.4 NBU to 67% at the established threshold for positivity of 0.5 NBU. Conclusions The CDC-NBA can detect inhibitors down to 0.2 NBU. The FLI, which is more sensitive, demonstrates anti-FVIII IgG 4 in some patients with negative (NBA, supporting the need for

  14. Factors limiting performance in a multitone intensity-discrimination task: disentangling non-optimal decision weights and increased internal noise.

    Directory of Open Access Journals (Sweden)

    Daniel Oberfeld

    Full Text Available To identify factors limiting performance in multitone intensity discrimination, we presented sequences of five pure tones alternating in level between loud (85 dB SPL and soft (30, 55, or 80 dB SPL. In the "overall-intensity task", listeners detected a level increment on all of the five tones. In the "masking task", the level increment was imposed only on the soft tones, rendering the soft tones targets and loud tones task-irrelevant maskers. Decision weights quantifying the importance of the five tone levels for the decision were estimated using methods of molecular psychophysics. Compatible with previous studies, listeners placed higher weights on the loud tones than on the soft tones in the overall-intensity condition. In the masking task, the decisions were systematically influenced by the to-be-ignored loud tones (maskers. Using a maximum-likelihood technique, we estimated the internal noise variance and tested whether the internal noise was higher in the alternating-level five-tone sequences than in sequences presenting only the soft or only the loud tones. For the overall-intensity task, we found no evidence for increased internal noise, but listeners applied suboptimal decision weights. These results are compatible with the hypothesis that the presence of the loud tones does not impair the precision of the representation of the intensity of the soft tones available at the decision stage, but that this information is not used in an optimal fashion due to a difficulty in attending to the soft tones. For the masking task, in some cases our data indicated an increase in internal noise. Additionally, listeners applied suboptimal decision weights. The maximum-likelihood analyses we developed should also be useful for other tasks or other sensory modalities.

  15. Controls on winter ecosystem respiration in temperate and boreal ecosystems

    Science.gov (United States)

    T. Wang; P. Ciais; S.L. Piao; C. Ottle; P. Brender; F. Maignan; A. Arain; A. Cescatti; D. Gianelle; C. Gough; L Gu; P. Lafleur; T. Laurila; B. Marcolla; H. Margolis; L. Montagnani; E. Moors; N. Saigusa; T. Vesala; G. Wohlfahrt; C. Koven; A. Black; E. Dellwik; A. Don; D. Hollinger; A. Knohl; R. Monson; J. Munger; A. Suyker; A. Varlagin; S. Verma

    2011-01-01

    Winter CO2 fluxes represent an important component of the annual carbon budget in northern ecosystems. Understanding winter respiration processes and their responses to climate change is also central to our ability to assess terrestrial carbon cycle and climate feedbacks in the future. However, the factors influencing the spatial and temporal...

  16. Urban ecosystem health assessment: a review.

    Science.gov (United States)

    Su, Meirong; Fath, Brian D; Yang, Zhifeng

    2010-05-15

    Due to the important role of cities for regional, national, and international economic development and the concurrent degradation of the urban environmental quality under rapid urbanization, a systematic diagnosis of urban ecosystem health for sustainable ecological management is urgently needed. This paper reviews the related research on urban ecosystem health assessment, beginning from the inception of urban ecosystem health concerns propelled by the development needs of urban ecosystems and the advances in ecosystem health research. Concepts, standards, indicators, models, and case studies are introduced and discussed. Urban ecosystem health considers the integration of ecological, economic, social and human health factors, and as such it is a value-driven concept which is strongly influenced by human perceptions. There is not an absolute urban ecosystem standard because of the uncertainty caused by the changing human needs, targets, and expectation of urban ecosystem over time; thus, suitable approaches are still needed to establish health standards of urban ecosystems. Several conceptual models and suitable indicator frameworks have been proposed to organize the multiple factors to represent comprehensively the health characteristics of an urban ecosystem, while certain mathematical methods have been applied to deal with the indicator information to get a clear assessment of the urban ecosystem health status. Instead of perceiving the urban ecosystem assessment as an instantaneous measurement of the health state, it is suggested to conceptualize the urban ecosystem health as a process, which impels us to focus more studies on the dynamic trends of health status and projecting possible development scenarios. Copyright 2010 Elsevier B.V. All rights reserved.

  17. An ecosystem approach to malaria control in an urban setting

    Directory of Open Access Journals (Sweden)

    Carrasquilla Gabriel

    2001-01-01

    Full Text Available We conducted a research project aimed at strengthening local government and the community for a sustainable malaria control strategy. The project began with a baseline diagnosis of malaria prevalence, a KAP survey, entomology, and health services delivery, after which an epidemiological study was performed to identify risk factors associated with malaria, thereafter used to plan intervention measures. A program evaluation was conducted five years later. By using an ecosystem approach to reanalyze data, this paper discusses how malaria arises from a complex interaction of cultural, economic, ecological, social, and individual factors. Intervention measures require an intersectorial and transdisciplinary approach that does not exist at the moment. Health sector leadership is limited, and there is no true community participation. Implications for research, including the use of qualitative and quantitative methods, study design, and complexity of data analysis are discussed. Finally, implications for malaria control are discussed, stressing the differences between the ecosystem and integrated disease control approaches.

  18. Application of eco-exergy for assessment of ecosystem health and development of structurally dynamic models

    DEFF Research Database (Denmark)

    Zhang, J.; Gürkan, Zeren; Jørgensen, S.E.

    2010-01-01

    Eco-exergy has been widely used in the assessment of ecosystem health, parameter estimations, calibrations, validations and prognoses. It offers insights into the understanding of ecosystem dynamics and disturbance-cl riven changes. Particularly, structurally dynamic models (SDMs), which...... are developed using eco-exergy as the goal function, have been applied in explaining and exploring ecosystem properties and changes in community structure driven by biotic and abiotic factors. In this paper, we review the application of eco-exergy for the assessment of ecosystem health and development...... of structurally dynamic models (SDMs). The limitations and possible future applications of the approach are also addressed. (C) 2009 Elsevier B.V. All rights reserved....

  19. PHYSICO-CHEMICAL LIMITATIVE FACTORS FOR GROWTH AND DEVELOPMENT IN STERLET (ACIPENSER RUTHENUS LINNAEUS, 1758 IN EXTENSIVELY SYSTEM

    Directory of Open Access Journals (Sweden)

    R. C. DIMA

    2009-10-01

    Full Text Available The oldest and most common method of increasing fish is a fish breeding ponds in which the supervision of nutrition and growth of biological material. Sterlet (Acipenser ruthenus ruthenus Linnaeus 1785 is the 4th of sturgeon scale and economic importance as a share of production of these fish .Monitoring of physicochemical parameters of sturgeons ponds has a crucial role to obtain satisfactory yields both in qualitative and quantitative. Chemical characteristics of water were determined in laboratory ecosystems Chemistry of the Institute of Research and Development for Ecology Aquaculture, Fisheries and Aquaculture Galaţi for the samples have been taken of the total water. Determination of the chemical characteristics was performed by standardized methods. Physic-chemical parameters of water were determined according to norm on the classification of surface water quality in order to establish the ecological status of water (Order no. 161/2006, for Class II of quality.

  20. Parallel ecological networks in ecosystems

    NARCIS (Netherlands)

    Olff, Han; Alonso, David; Berg, Matty P.; Eriksson, B. Klemens; Loreau, Michel; Piersma, Theunis; Rooney, Neil

    2009-01-01

    In ecosystems, species interact with other species directly and through abiotic factors in multiple ways, often forming complex networks of various types of ecological interaction. Out of this suite of interactions, predator-prey interactions have received most attention. The resulting food webs,

  1. L-Arginine is not the limiting factor for nitric oxide synthesis by human alveolar macrophages in vitro

    NARCIS (Netherlands)

    Muijsers, RBR; ten Hacken, NHT; Van Ark, [No Value; Folkerts, G; Nijkamp, FP; Postma, DS

    2001-01-01

    Unlike murine mononuclear phagocytes, human macrophages do not release high amounts of nitric oxide (NO) in vitro despite the presence of nitric oxide synthase (NOS). To determine whether this limited NO synthesis in vitro is due to limited availability of the NOS substrate L-arginine, and putative

  2. Ecosystem degradation in India

    International Nuclear Information System (INIS)

    Sinha, B.N.

    1990-01-01

    Environmental and ecosystem studies have assumed greater relevance in the last decade of the twentieth century than even before. The urban settlements are becoming over-crowded and industries are increasingly polluting the air, water and sound in our larger metropolises. Degradation of different types of ecosystem are discussed in this book, Ecosystem Degradation in India. The book has been divided into seven chapters: Introduction, Coastal and Delta Ecosystem, River Basin Ecosystem, Mountain Ecosystem, Forest Ecosystem, Urban Ecosystem and the last chapter deals with the Environmental Problems and Planning. In the introduction the environmental and ecosystem degradation problems in India is highlighted as a whole while in other chapters mostly case studies by experts who know their respective terrain very intimately are included. The case study papers cover most part of India and deal with local problems, stretching from east coast to west coast and from Kashmir to Kanyakumari. (author)

  3. Transformation of Digital Ecosystems

    DEFF Research Database (Denmark)

    Henningsson, Stefan; Hedman, Jonas

    2014-01-01

    the Digital Ecosystem Technology Transformation (DETT) framework for explaining technology-based transformation of digital ecosystems by integrating theories of business and technology ecosystems. The framework depicts ecosystem transformation as distributed and emergent from micro-, meso-, and macro- level...... coopetition. The DETT framework consists an alternative to the existing explanations of digital ecosystem transformation as the rational management of one central actor balancing ecosystem tensions. We illustrate the use of the framework by a case study of transformation in the digital payment ecosystem......In digital ecosystems, the fusion relation between business and technology means that the decision of technical compatibility of the offering is also the decision of how to position the firm relative to the coopetive relations that characterize business ecosystems. In this article we develop...

  4. Recent population size, trends, and limiting factors for the double-crested Cormorant in Western North America

    Science.gov (United States)

    Adkins, Jessica Y.; Roby, Daniel D.; Lyons, Donald E.; Courtot, Karen N.; Collis, Ken; Carter, Harry R.; Shuford, W. David; Capitolo, Phillip J.

    2014-01-01

    colonies by bald eagles (Haliaeetus leucocephalus) and humans are likely limiting factors on the growth of the western population at present. Because of differences in biology and management, the western population of double-crested cormorants warrants consideration as a separate management unit from the population east of the Continental Divide.

  5. Applied Ecosystem Analysis - Background : EDT the Ecosystem Diagnosis and Treatment Method.

    Energy Technology Data Exchange (ETDEWEB)

    Mobrand, Lars E.

    1996-05-01

    This volume consists of eight separate reports. We present them as background to the Ecosystem Diagnosis and Treatment (EDT) methodology. They are a selection from publications, white papers, and presentations prepared over the past two years. Some of the papers are previously published, others are currently being prepared for publication. In the early to mid 1980`s the concern for failure of both natural and hatchery production of Columbia river salmon populations was widespread. The concept of supplementation was proposed as an alternative solution that would integrate artificial propagation with natural production. In response to the growing expectations placed upon the supplementation tool, a project called Regional Assessment of Supplementation Project (RASP) was initiated in 1990. The charge of RASP was to define supplementation and to develop guidelines for when, where and how it would be the appropriate solution to salmon enhancement in the Columbia basin. The RASP developed a definition of supplementation and a set of guidelines for planning salmon enhancement efforts which required consideration of all factors affecting salmon populations, including environmental, genetic, and ecological variables. The results of RASP led to a conclusion that salmon issues needed to be addressed in a manner that was consistent with an ecosystem approach. If the limitations and potentials of supplementation or any other management tool were to be fully understood it would have to be within the context of a broadly integrated approach - thus the Ecosystem Diagnosis and Treatment (EDT) method was born.

  6. Applied Ecosystem Analysis - Background EDT - The Ecosystem Diagnosis and Treatment Method

    International Nuclear Information System (INIS)

    Mobrand, L.E.; Lichatowich, J.A.; Howard, D.A.; Vogel, T.S.

    1996-05-01

    This volume consists of eight separate reports. We present them as background to the Ecosystem Diagnosis and Treatment (EDT) methodology. They are a selection from publications, white papers, and presentations prepared over the past two years. Some of the papers are previously published, others are currently being prepared for publication. In the early to mid 1980's the concern for failure of both natural and hatchery production of Columbia river salmon populations was widespread. The concept of supplementation was proposed as an alternative solution that would integrate artificial propagation with natural production. In response to the growing expectations placed upon the supplementation tool, a project called Regional Assessment of Supplementation Project (RASP) was initiated in 1990. The charge of RASP was to define supplementation and to develop guidelines for when, where and how it would be the appropriate solution to salmon enhancement in the Columbia basin. The RASP developed a definition of supplementation and a set of guidelines for planning salmon enhancement efforts which required consideration of all factors affecting salmon populations, including environmental, genetic, and ecological variables. The results of RASP led to a conclusion that salmon issues needed to be addressed in a manner that was consistent with an ecosystem approach. If the limitations and potentials of supplementation or any other management tool were to be fully understood it would have to be within the context of a broadly integrated approach - thus the Ecosystem Diagnosis and Treatment (EDT) method was born

  7. Uncovering Ecosystem Service Bundles through Social Preferences

    Science.gov (United States)

    Martín-López, Berta; Iniesta-Arandia, Irene; García-Llorente, Marina; Palomo, Ignacio; Casado-Arzuaga, Izaskun; Amo, David García Del; Gómez-Baggethun, Erik; Oteros-Rozas, Elisa; Palacios-Agundez, Igone; Willaarts, Bárbara; González, José A.; Santos-Martín, Fernando; Onaindia, Miren; López-Santiago, Cesar; Montes, Carlos

    2012-01-01

    Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem’s capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem’s capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area) have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis). We found a clear trade-off among provisioning services (and recreational hunting) versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs. PMID:22720006

  8. Energy efficiency : potential fuel savings generated by a national speed limit would be influenced by many other factors.

    Science.gov (United States)

    2008-11-07

    "Congress expressed interest in obtaining information on using a national speed limit to reduce fuel consumption. In response to the request, we reviewed existing literature and consulted knowledgeable stakeholders on the following: (1) What is the r...

  9. Payment for ecosystem services

    DEFF Research Database (Denmark)

    Zandersen, Marianne; Oddershede, Jakob Stoktoft; Pedersen, Anders Branth

    Research question: Northern Europe experiences an increasingly wet climate, leading to more frequent and severe fluvial flood events. Ecosystem-based Adaptation (EbA) is becoming recognised as a valuable yet under-utilised means to alleviating negative effects of a changing climate. This however...... that would allow the local municipality to periodically flood farmland in order to avoid or limit urban flooding from Storåen. The experiment aims to estimate the costs of getting farmers to participate in the scheme, which would represent (some of) the costs of reducing climate change problems in the town...... of Holstebro. In a number of choice occasions, farmers were asked to select between either no contract or contracts characterised by a set of positive and negative attributes, including a whether or not to require specific flood resistant crops or not; whether to allow for a compensation in case of crop loss...

  10. Obesity as a risk factor for developing functional limitation among older adults: A conditional inference tree analysis

    Science.gov (United States)

    Objective: To examine the risk factors of developing functional decline and make probabilistic predictions by using a tree-based method that allows higher order polynomials and interactions of the risk factors. Methods: The conditional inference tree analysis, a data mining approach, was used to con...

  11. Coral reefs - Specialized ecosystems

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, M.V.M.

    This paper discusses briefly some aspects that characterize and differentiate coral reef ecosystems from other tropical marine ecosystems. A brief account on the resources that are extractable from coral reefs, their susceptibility to natural...

  12. Parallel ecological networks in ecosystems

    Science.gov (United States)

    Olff, Han; Alonso, David; Berg, Matty P.; Eriksson, B. Klemens; Loreau, Michel; Piersma, Theunis; Rooney, Neil

    2009-01-01

    In ecosystems, species interact with other species directly and through abiotic factors in multiple ways, often forming complex networks of various types of ecological interaction. Out of this suite of interactions, predator–prey interactions have received most attention. The resulting food webs, however, will always operate simultaneously with networks based on other types of ecological interaction, such as through the activities of ecosystem engineers or mutualistic interactions. Little is known about how to classify, organize and quantify these other ecological networks and their mutual interplay. The aim of this paper is to provide new and testable ideas on how to understand and model ecosystems in which many different types of ecological interaction operate simultaneously. We approach this problem by first identifying six main types of interaction that operate within ecosystems, of which food web interactions are one. Then, we propose that food webs are structured among two main axes of organization: a vertical (classic) axis representing trophic position and a new horizontal ‘ecological stoichiometry’ axis representing decreasing palatability of plant parts and detritus for herbivores and detrivores and slower turnover times. The usefulness of these new ideas is then explored with three very different ecosystems as test cases: temperate intertidal mudflats; temperate short grass prairie; and tropical savannah. PMID:19451126

  13. Hysteresis response of daytime net ecosystem exchange during drought

    Directory of Open Access Journals (Sweden)

    N. Pingintha

    2010-03-01

    Full Text Available Continuous measurements of net ecosystem CO2 exchange (NEE using the eddy-covariance method were made over an agricultural ecosystem in the southeastern US. During optimum environmental conditions, photosynthetically active radiation (PAR was the primary driver controlling daytime NEE, accounting for as much as 67 to 89% of the variation in NEE. However, soil water content became the dominant factor limiting the NEE-PAR response during the peak growth stage. NEE was significantly depressed when high PAR values coincided with very low soil water content. The presence of a counter-clockwise hysteresis of daytime NEE with PAR was observed during periods of water stress. This is a result of the stomatal closure control of photosynthesis at high vapor pressure deficit and enhanced respiration at high temperature. This result is significant since this hysteresis effect limits the range of applicability of the Michaelis-Menten equation and other related expressions in the determination of daytime NEE as a function of PAR. The systematic presence of hysteresis in the response of NEE to PAR suggests that the gap-filling technique based on a non-linear regression approach should take into account the presence of water-limited field conditions. Including this step is therefore likely to improve current evaluation of ecosystem response to increased precipitation variability arising from climatic changes.

  14. The abiotic and biotic factors limiting establishment of predatory fishes at their expanding northern range boundaries in Ontario, Canada.

    Science.gov (United States)

    Alofs, Karen M; Jackson, Donald A

    2015-06-01

    There is a poor understanding of the importance of biotic interactions in determining species distributions with climate change. Theory from invasion biology suggests that the success of species introductions outside of their historical ranges may be either positively (biotic acceptance) or negatively (biotic resistance) related to native biodiversity. Using data on fish community composition from two survey periods separated by approximately 28 years during which climate was warming, we examined the factors influencing the establishment of three predatory centrarchids: Smallmouth Bass (Micropterus dolomieu), Largemouth Bass (M. salmoides), and Rock Bass (Ambloplites rupestris) in lakes at their expanding northern range boundaries in Ontario. Variance partitioning demonstrated that, at a regional scale, abiotic factors play a stronger role in determining the establishment of these species than biotic factors. Pairing lakes within watersheds where each species had established with lakes sharing similar abiotic conditions where the species had not established revealed both positive and negative relationships between the establishment of centrarchids and the historical presence of other predatory species. The establishment of these species near their northern range boundaries is primarily determined by abiotic factors at a regional scale; however, biotic factors become important at the lake-to-lake scale. Studies of exotic species invasions have previously highlighted how spatial scale mediates the importance of abiotic vs. biotic factors on species establishment. Our study demonstrates how concepts from invasion biology can inform our understanding of the factors controlling species distributions with changing climate. © 2014 John Wiley & Sons Ltd.

  15. Limited socioeconomic opportunities and Latina teen childbearing: a qualitative study of family and structural factors affecting future expectations.

    Science.gov (United States)

    Minnis, Alexandra M; Marchi, Kristen; Ralph, Lauren; Biggs, M Antonia; Combellick, Sarah; Arons, Abigail; Brindis, Claire D; Braveman, Paula

    2013-04-01

    The decrease in adolescent birth rates in the United States has been slower among Latinas than among other ethnic/racial groups. Limited research has explored how socioeconomic opportunities influence childbearing among Latina adolescents. We conducted in-depth interviews with 65 pregnant foreign- and US-born Latina women (31 adolescents; 34 adults) in two California counties. We assessed perceived socioeconomic opportunities and examined how family, immigration and acculturation affected the relationships between socioeconomic opportunities and adolescent childbearing. Compared with women who delayed childbearing into adulthood, pregnant adolescents described having few resources for educational and career development and experiencing numerous socioeconomic and social barriers to achieving their goals. Socioeconomic instability and policies limiting access to education influenced childbearing for immigrant adolescents. In contrast, family disintegration tied to poverty figured prominently in US-born adolescents' childbearing. Limited socioeconomic opportunities may play a large role in persistently high pregnancy rates among Latina adolescents.

  16. Rights to ecosystem services

    NARCIS (Netherlands)

    Davidson, M.

    2014-01-01

    Ecosystem services are the benefits people obtain from ecosystems. Many of these services are provided outside the borders of the land where they are produced; this article investigates who is entitled to these non-excludable ecosystem services from two libertarian perspectives. Taking a

  17. Towards ecosystem accounting

    NARCIS (Netherlands)

    Duku, C.; Rathjens, H.; Zwart, S.J.; Hein, L.

    2015-01-01

    Ecosystem accounting is an emerging field that aims to provide a consistent approach to analysing environment-economy interactions. One of the specific features of ecosystem accounting is the distinction between the capacity and the flow of ecosystem services. Ecohydrological modelling to support

  18. Global Ecosystem Restoration Index

    DEFF Research Database (Denmark)

    Fernandez, Miguel; Garcia, Monica; Fernandez, Nestor

    2015-01-01

    The Global ecosystem restoration index (GERI) is a composite index that integrates structural and functional aspects of the ecosystem restoration process. These elements are evaluated through a window that looks into a baseline for degraded ecosystems with the objective to assess restoration...

  19. Ecosystem classification, Chapter 2

    Science.gov (United States)

    M.J. Robin-Abbott; L.H. Pardo

    2011-01-01

    The ecosystem classification in this report is based on the ecoregions developed through the Commission for Environmental Cooperation (CEC) for North America (CEC 1997). Only ecosystems that occur in the United States are included. CEC ecoregions are described, with slight modifications, below (CEC 1997) and shown in Figures 2.1 and 2.2. We chose this ecosystem...

  20. Can we manage ecosystems in a sustainable way?

    Science.gov (United States)

    Rice, Jake

    Fisheries have often become unsustainable, despite efforts of policy, management, and science. FAO has reviewed this undesirable pattern and identified six major factors contributing to unsustainability: inappropriate incentives, high demand for limited resources, poverty and lack of alternatives, complexity and lack of knowledge, lack of effective governance, and interactions of fisheries sector with other sectors and the environment. It also identified eight classes of actions that provide pathways to addressing the factors causing unsustainability of fisheries: allocation of rights; transparent, participatory management; support for science, enforcement and planning; equitable distribution of benefits; integrated policy development; application of precaution; building capacity and public understanding; and market incentives and economic instruments. The review highlighted that "sustainability" is a multi-dimensional concept (economic, social, ecological, and institutional), and measures implemented to address problems on one dimension of sustainability will move the fishery in a negative direction in at least one other dimension. In this paper I apply the FAO framework to the whole ecosystem. For each factor of unsustainability, I consider whether redefining the sustainability problem to the greater ecosystem makes the factor more or less serious as a threat to sustainability. For each pathway to improvement I consider whether the redefinition of the problem makes the pathway more or less effective as a management response to the threat. Few of the factors of unsustainability becomes easier to address at the ecosystem scale, and several of them become much more difficult. Of the combinations of pathways of responses and factors of unsustainability, more than two thirds of them become more difficult to apply, and/or have even greater negative impacts on other dimensions of sustainability. Importantly, the most promising pathways for addressing unsustainability of

  1. Introduction to the application and limits of anomalous X-ray diffraction in the determination of partial structure factors

    International Nuclear Information System (INIS)

    Bienenstock, A.

    1993-01-01

    The use of anomalous X-ray scattering to obtain the first differences and partial structure factors normally obtained with isotopic substitution neutron diffraction is described and compared with the neutron technique. Both the problems associated with the X-ray technique (low-Z problems, scattering factor problems, Compton scattering problems, fluorescence problems, storage ring stability problems) and the situations in which it is highly valuable are discussed. 12 refs

  2. Low skeletal muscle mass is a predictive factor for chemotherapy dose-limiting toxicity in patients with locally advanced head and neck cancer

    NARCIS (Netherlands)

    Wendrich, Anne W; Swartz, Justin E; Bril, Sandra I; Wegner, Inge; de Graeff, Alexander; Smid, Ernst J; de Bree, Remco; Pothen, Ajit J

    OBJECTIVES: Low skeletal muscle mass (SMM) or sarcopenia is emerging as an adverse prognostic factor for chemotherapy dose-limiting toxicity (CLDT) and survival in cancer patients. Our aim was to determine the impact of low SMM on CDLT in patients with locally advanced head and neck squamous cell

  3. Ecosystem services in ECOCLIM

    DEFF Research Database (Denmark)

    Sørensen, Lise Lotte; Boegh, Eva; Bendtsen, J

    that actions initiated to reduce anthropogenic GHG emissions are sustainable and not destructive to existing ecosystem services. Therefore it is important to address i.e. land use change in relation to the regulating services of the ecosystems, such as carbon sequestration and climate regulation. At present...... a thorough understanding of the ecosystem processes controlling the uptake or emissions of GHG is fundamental. Here we present ECOCLIM in the context of ecosystem services and the experimental studies within ECOCLIM which will lead to an enhanced understanding of Danish ecosystems....

  4. A decade of insights into grassland ecosystem responses to global environmental change

    Science.gov (United States)

    Borer, Elizabeth T.; Grace, James B.; Harpole, W. Stanley; MacDougall, Andrew S.; Seabloom, Eric W.

    2017-01-01

    Earth’s biodiversity and carbon uptake by plants, or primary productivity, are intricately interlinked, underlie many essential ecosystem processes, and depend on the interplay among environmental factors, many of which are being changed by human activities. While ecological theory generalizes across taxa and environments, most empirical tests of factors controlling diversity and productivity have been observational, single-site experiments, or meta-analyses, limiting our understanding of variation among site-level responses and tests of general mechanisms. A synthesis of results from ten years of a globally distributed, coordinated experiment, the Nutrient Network (NutNet), demonstrates that species diversity promotes ecosystem productivity and stability, and that nutrient supply and herbivory control diversity via changes in composition, including invasions of non-native species and extinction of native species. Distributed experimental networks are a powerful tool for tests and integration of multiple theories and for generating multivariate predictions about the effects of global changes on future ecosystems.

  5. Fishing for ecosystem services

    Science.gov (United States)

    Pope, Kevin L.; Pegg, Mark A.; Cole, Nicholas W.; Siddons, Stephen F.; Fedele, Alexis D.; Harmon, Brian S.; Ruskamp, Ryan L.; Turner, Dylan R.; Uerling, Caleb C.

    2016-01-01

    Ecosystems are commonly exploited and manipulated to maximize certain human benefits. Such changes can degrade systems, leading to cascading negative effects that may be initially undetected, yet ultimately result in a reduction, or complete loss, of certain valuable ecosystem services. Ecosystem-based management is intended to maintain ecosystem quality and minimize the risk of irreversible change to natural assemblages of species and to ecosystem processes while obtaining and maintaining long-term socioeconomic benefits. We discuss policy decisions in fishery management related to commonly manipulated environments with a focus on influences to ecosystem services. By focusing on broader scales, managing for ecosystem services, and taking a more proactive approach, we expect sustainable, quality fisheries that are resilient to future disturbances. To that end, we contend that: (1) management always involves tradeoffs; (2) explicit management of fisheries for ecosystem services could facilitate a transition from reactive to proactive management; and (3) adaptive co-management is a process that could enhance management for ecosystem services. We propose adaptive co-management with an ecosystem service framework where actions are implemented within ecosystem boundaries, rather than political boundaries, through strong interjurisdictional relationships.

  6. Fishing for ecosystem services.

    Science.gov (United States)

    Pope, Kevin L; Pegg, Mark A; Cole, Nicholas W; Siddons, Stephen F; Fedele, Alexis D; Harmon, Brian S; Ruskamp, Ryan L; Turner, Dylan R; Uerling, Caleb C

    2016-12-01

    Ecosystems are commonly exploited and manipulated to maximize certain human benefits. Such changes can degrade systems, leading to cascading negative effects that may be initially undetected, yet ultimately result in a reduction, or complete loss, of certain valuable ecosystem services. Ecosystem-based management is intended to maintain ecosystem quality and minimize the risk of irreversible change to natural assemblages of species and to ecosystem processes while obtaining and maintaining long-term socioeconomic benefits. We discuss policy decisions in fishery management related to commonly manipulated environments with a focus on influences to ecosystem services. By focusing on broader scales, managing for ecosystem services, and taking a more proactive approach, we expect sustainable, quality fisheries that are resilient to future disturbances. To that end, we contend that: (1) management always involves tradeoffs; (2) explicit management of fisheries for ecosystem services could facilitate a transition from reactive to proactive management; and (3) adaptive co-management is a process that could enhance management for ecosystem services. We propose adaptive co-management with an ecosystem service framework where actions are implemented within ecosystem boundaries, rather than political boundaries, through strong interjurisdictional relationships. Published by Elsevier Ltd.

  7. Exploring the interaction of activity limitations with context, systems, community and personal factors in accessing public health care services: A presentation of South African case studies.

    Science.gov (United States)

    Mji, Gubela; Braathen, Stine H; Vergunst, Richard; Scheffler, Elsje; Kritzinger, Janis; Mannan, Hasheem; Schneider, Marguerite; Swartz, Leslie; Visagie, Surona

    2017-02-08

    There are many factors that influence access to public health services, such as the context people live in, the existing health services, and personal, cultural and community factors. People with disabilities (activity limitations), through their experience of health services, may offer a particular understanding of the performance of the health services, thus exposing health system limitations more clearly than perhaps any other health service user. This article explores how activity limitations interact with factors related to context, systems, community and personal factors in accessing public health care services in South Africa. We present four case studies of people with disabilities from four low-resource diverse contexts in South Africa (rural, semi-rural, farming community and peri-urban) to highlight challenges of access to health services experienced by people with activity limitations in a variety of contexts. One case study of a person with disabilities was chosen from each study setting to build evidence using an intensive qualitative case study methodology to elucidate individual and household experiences of challenges experienced by people with activity limitations when attempting to access public health services. In-depth interviews were used to collect data, using an interview guide. The analysis was conducted in the form of a thematic analysis using the interview topics as a starting point. First, these four case studies demonstrate that equitable access to health services for people with activity limitations is influenced by a complex interplay of a variety of factors for a single individual in a particular context. Secondly, that while problems with access to public health services are experienced by everyone, people with activity limitations are affected in particular ways making them particularly vulnerable in using public health services. The revitalisation of primary health care and the introduction of national health

  8. Biotic, abiotic, and management controls on the net ecosystem CO2 exchange of European mountain grassland ecosystems

    DEFF Research Database (Denmark)

    Wohlfahrt, Georg; Anderson-Dunn, Margaret; Bahn, Michael

    2008-01-01

    The net ecosystem carbon dioxide (CO2) exchange (NEE) of nine European mountain grassland ecosystems was measured during 2002-2004 using the eddy covariance method. Overall, the availability of photosynthetically active radiation (PPFD) was the single most important abiotic influence factor for NEE...... mountain grassland ecosystems to climatic drivers....

  9. Net ecosystem CO2 exchange over a larch forest in Hokkaido, Japan

    International Nuclear Information System (INIS)

    Huimin Wang; Saigusa, Nobuko; Yamamoto, Susumu; Kondo, Hiroaki; Hirano, Takashi; Toriyama, Atsushi; Fujinuma, Yasumi

    2004-01-01

    Larch forests are distributed extensively in the east Eurasian continent and are expected to play a significant role in the terrestrial ecosystem carbon cycling process. In view of the fact that studies on carbon exchange for this important biome have been very limited, we have initiated a long-term flux observation in a larch forest ecosystem in Hokkaido in northern Japan since 2000. The net ecosystem CO 2 exchange (NEE) showed large seasonal and diurnal variation. Generally, the larch forest ecosystem released CO 2 in nighttime and assimilated CO 2 in daytime during the growing season from May to October. The ecosystem started to become a net carbon sink in May, reaching a maximum carbon uptake as high as 186 g C m -2 month -1 in June. With the yellowing, senescing and leaf fall, the ecosystem turned into a carbon source in November. During the non-growing season, the larch forest ecosystem became a net source of CO 2 , releasing an average of 16.7 g C m -2 month -1 . Overall, the ecosystem sequestered 141-240 g C m -2 yr -1 in 2001. The NEE was significantly influenced by environmental factors. Respiration of the ecosystem, for example, was exponentially dependent on air temperature, while photosynthesis was related to the incident PAR in a manner consistent with the Michaelis-Menten model. Although the vapor pressure deficit (VPD) was scarcely higher than 15 hPa, the CO 2 uptake rate was also depressed when VPD surpassed 10 hPa (Author)

  10. Responses of coastal ecosystems to environmental variability in emerging countries from the Americas

    Science.gov (United States)

    Muniz, Pablo; Calliari, Danilo; Giménez, Luis; Defeo, Omar

    2015-12-01

    Coastal ecosystems supply critical ecological services and benefits to human society (Barbier et al., 2011). Nearly 38% of the global monetary value of annual ecosystem services arises from estuaries, seagrass and algal beds, coral reefs and shelf ecosystems (Costanza et al., 1997). However, these ecosystems are being increasingly affected by multiple drivers acting simultaneously at several spatial and temporal scales (Lotze et al., 2006; Hoegh-Guldberg and Bruno, 2010). Climate change (temperature increase, sea level rise, ocean acidification), human activities (e.g. land use/cover change, pollution, overexploitation, translocation of species), and extreme natural events (storms, floods, droughts) are the most important drivers degrading the resilience of coastal systems. Such factors operate on individual level processes, leading organisms away from their niches (Steinberg, 2013) or modifying rates and phenology (Giménez, 2011; Mackas et al., 2012, Deutsch et al., 2015). All of these influence ecosystem level processes, causing changes in species composition, diversity losses and deterioration of ecosystem functions (Worm et al., 2006; Defeo et al., 2009; Doney et al., 2011; Dornelas et al., 2014). The rate of change in habitats, species distributions and whole ecosystems has accelerated over the past decades as shown, for example, in the increase in the frequency of events of coastal hypoxia (Diaz and Rosenberg, 2008,Vaquer-Sunyer and Duarte, 2008), extensive translocation of species by global shipping (Seebens et al., 2013), and in ecosystem regime shifts (Möllmann et al., 2015 and references therein). Some coastal areas have been transformed into novel ecosystems with physical and biological characteristics outside their natural range of variability (Cloern et al., 2015) while others are likely to become sink areas, limiting the migration of marine species away from warming habitats (Burrows et al., 2014).

  11. From individuals to ecosystem function: toward an integration of evolutionary and ecosystem ecology.

    Science.gov (United States)

    Schmitz, Oswald J; Grabowski, Jonathan H; Peckarsky, Barbara L; Preisser, Evan L; Trussell, Geoffrey C; Vonesh, James R

    2008-09-01

    An important goal in ecology is developing general theory on how the species composition of ecosystems is related to ecosystem properties and functions. Progress on this front is limited partly because of the need to identify mechanisms controlling functions that are common to a wide range of ecosystem types. We propose that one general mechanism, rooted in the evolutionary ecology of all species, is adaptive foraging behavior in response to predation risk. To support our claim, we present two kinds of empirical evidence from plant-based and detritus-based food chains of terrestrial and aquatic ecosystems. The first kind comes from experiments that explicitly trace how adaptive foraging influences ecosystem properties and functions. The second kind comes from a synthesis of studies that individually examine complementary components of particular ecosystems that together provide an integrated perspective on the link between adaptive foraging and ecosystem function. We show that the indirect effects of predators on plant diversity, plant productivity, nutrient cycling, trophic transfer efficiencies, and energy flux caused by consumer foraging shifts in response to risk are qualitatively different from effects caused by reductions in prey density due to direct predation. We argue that a perspective of ecosystem function that considers effects of consumer behavior in response to predation risk will broaden our capacity to explain the range of outcomes and contingencies in trophic control of ecosystems. This perspective also provides an operational way to integrate evolutionary and ecosystem ecology, which is an important challenge in ecology.

  12. Diapause induction as an interplay between seasonal token stimuli, and modifying and directly limiting factors: hibernation in Chymomyza costata

    Czech Academy of Sciences Publication Activity Database

    Košťál, Vladimír; Mollaei, M.; Schöttner, Konrad

    2016-01-01

    Roč. 41, č. 4 (2016), s. 344-357 ISSN 0307-6962 R&D Projects: GA ČR GA13-01057S Institutional support: RVO:60077344 Keywords : environmental signals * overcrowding * photoperiodism Subject RIV: ED - Physiology Impact factor: 1.364, year: 2016 http://onlinelibrary.wiley.com/doi/10.1111/phen.12159/abstract

  13. Limited human epidermal growth factor receptor 2 discordance in metastatic breast cancer patients treated with trastuzumab, a population based study

    NARCIS (Netherlands)

    van Rooijen, J.M.; de Munck, L.; de Graaf, J.C.; Siesling, Sabine; de Vries, Erik G.; Boers, J.E.

    2014-01-01

    Background Accurate assessment of the human epidermal growth factor receptor 2 (HER2) in breast cancer is essential for proper treatment decisions. HER2 positivity confirmation rates in breast cancer trials by central testing pathology laboratories were reported to be approximately 85%. The aim of

  14. Limited human epidermal growth factor receptor 2 discordance in metastatic breast cancer patients treated with trastuzumab, a population based study

    NARCIS (Netherlands)

    van Rooijen, J. M.; de Munck, L.; de Graaf, J. C.; Siesling, S.; de Vries, E. G.; Boers, J. E.

    Background: Accurate assessment of the human epidermal growth factor receptor 2 (HER2) in breast cancer is essential for proper treatment decisions. HER2 positivity confirmation rates in breast cancer trials by central testing pathology laboratories were reported to be approximately 85%. The aim of

  15. Textiles: Some technocal information and data II: Conversion factors, fibre properties, spinning limits, typical twist factors, weaving performannce and transfer printing temperatures.

    CSIR Research Space (South Africa)

    Hunter, L

    1978-07-01

    Full Text Available to compile some facts and figures which are often required in the textile industry. CONVERSION FACTORS AND OTHER DATA The trend throughout the world is towards the use of metric units, or more particularly the SI units. Some of the units commonly...

  16. The Multifaceted Aspects of Ecosystem Integrity

    Directory of Open Access Journals (Sweden)

    Giulio A. De Leo

    1997-06-01

    Full Text Available The need to reduce human impacts on ecosystems creates pressure for adequate response, but the rush to solutions fosters the oversimplification of such notions as sustainable development and ecosystem health. Hence, it favors the tendency to ignore the complexity of natural systems. In this paper, after a brief analysis of the use and abuse of the notion of ecosystem health, we address the problem of a sound definition of ecosystem integrity, critically review the different methodological and conceptual approaches to the management of natural resources, and sketch the practical implications stemming from their implementation. We show thatthere are merits and limitations in different definitions of ecosystem integrity, for each acknowledges different aspects of ecosystem structure and functioning and reflects the subjective perspectives of humans on the value, importance, and role of biological diversity. This evaluation is based on a brief sketch of the links among biodiversity, ecosystem functioning and resilience, and a description of the problems that arise in distinguishing between natural and anthropogenic disturbance. We also emphasize the difficulty of assessing the economic value of species and habitats and the need to use adaptive management policies to deal with uncertainty and ecosystem complexity. In conclusion, while acknowledging that environmental legislation requires objective statements on ecosystem status and trends, we stress that the notion of ecological integrity is so complex that its measure cannot be expressed through a single indicator, but rather requires a set of indicators at different spatial, temporal, and hierarchical levels of ecosystem organization. Ecosystem integrity is not an absolute, monolithic concept. The existence of different sets of values regarding biological diversity and environmental risks must be explicitly accounted for and incorporated in the decision process, rather than ignored or averaged out.

  17. Limiting factors to oxygen transport on Mount Everest 30 years after: a critique of Paolo Cerretelli's contribution to the study of altitude physiology.

    Science.gov (United States)

    Ferretti, Guido

    2003-10-01

    In 1976, Paolo Cerretelli published an article entitled "Limiting factors to oxygen transport on Mount Everest" in the Journal of Applied Physiology. The paper demonstrated the role of cardiovascular oxygen transport in limiting maximal oxygen consumption (VO2max). In agreement with the predominant view of VO2max limitation at that time, however, its results were taken to mean that cardiovascular oxygen transport does not limit VO2max at altitude. So it was argued that the limiting factor could be in the periphery, and muscle blood flow was proposed as a possible candidate. Despite this suggestion, the conclusion generated a series of papers on muscle structural characteristics. These experiments demonstrated a loss of muscle oxidative capacity in chronic hypoxia, and thus provided an unambiguous refutation of the then widespread hypothesis that an increased muscle oxidative capacity is needed at altitude to compensate for the lack of oxygen. This analysis is followed by a short account of Cerretelli's more recent work, with a special attention to the subject of the so-called "lactate paradox".

  18. Valuation of rangeland ecosystem services

    Science.gov (United States)

    Gascoigne, W.R.

    2011-01-01

    into analyzing the costs and benefits associated with policies being proposed, or possibly already implemented. For example, with monetized values acting as a common metric, one could compare the 'benefits' of converting a rangeland ecosystem for commercial development (perhaps estimated at the market value of the developed land) with the foregone ecosystem service values (in addition to any land income lost) resulting from that land conversion. Similarly, ecosystem service values can be used to determine the level of return on an investment. rhis is a primary objective for private land conservation organizations who typically have very limited resources. Ecosystem service valuation can also have a role in damage assessments from incidents that require compensation such as oil spills. Additionally, valuation can be very informative when investigating regulatory programs that trade ecological assets such as wetland mitigation programs. Typically these programs are based simply on an 'acre for acre' criterion, and do not take into consideration varying welfare values associated with that ecosystem. Lastly, and most fundamental, ecosystem service valuation serves as a recognition tool for people of all backgrounds. Identifying and valuing ecosystem goods and services on rangelands brings to light the value these natural assets have to human welfare that often remain hidden do to their public and non-market attributes. This type of recognition is vital to the preservation of rangeland ecosystems in the future and the many ecological benefits they provide.

  19. Review of compartmental analysis in ecosystem science

    International Nuclear Information System (INIS)

    O'Neill, R.V.

    1978-01-01

    The compartment model has a large number of applications in ecosystem science. An attempt is made to outline the problem areas and objectives for which this type of model has particular advantages. The areas identified are an adequate model of tracer movement through an undisturbed but non-equilibrium ecosystem; an adequate model of the movement of material in greater than tracer quantity through an ecosystem near steady state; a minimal model based on limited data; a tool for extrapolating past trends; a framework for the summarization of large data sets; and a theoretical tool for exploring and comparing limited aspects of ecosystem dynamics. The review is set in an historical perspective which helps explain why these models were adopted in ecology. References are also provided to literature which documents available mathematical techniques in an ecological context

  20. Assessing streamflow characteristics as limiting factors on benthic invertebrate assemblages in streams across the western United States

    Science.gov (United States)

    Konrad, C.P.; Brasher, A.M.D.; May, J.T.

    2008-01-01

    1. Human use of land and water resources modifies many streamflow characteristics, which can have significant ecological consequences. Streamflow and invertebrate data collected at 111 sites in the western U.S.A. were analysed to identify streamflow characteristics (magnitude, frequency, duration, timing and variation) that are probably to limit characteristics of benthic invertebrate assemblages (abundance, richness, diversity and evenness, functional feeding groups and individual taxa) and, thus, would be important for freshwater conservation and restoration. Our analysis investigated multiple metrics for each biological and hydrological characteristic, but focuses on 14 invertebrate metrics and 13 streamflow metrics representing the key associations between streamflow and invertebrates.

  1. Vibrational spectroscopies for the analysis of cutaneous permeation: experimental limiting factors identified in the case of caffeine penetration.

    Science.gov (United States)

    Tfaili, Sana; Gobinet, Cyril; Josse, Gwendal; Angiboust, Jean-François; Baillet, Arlette; Manfait, Michel; Piot, Olivier

    2013-02-01

    Caffeine is utilised as a reference for permeation studies in dermatology and cosmetology. The present work aimed to monitor the permeation of a caffeine solution through the skin. For this purpose, Raman and infrared studies were performed. Raman microspectroscopy permitted a dynamic follow-up of the caffeine diffusion. In complementary, infrared microimaging provided information of the caffeine localization in the skin by applying multivariate statistical processing on skin tissue sections. Herein, we prove the possibility of tracking low concentrations of caffeine through the skin and we highlight some experimental limitations of vibrational spectroscopies.

  2. Meaningful learning: The essential factor for conceptual change in limited or inappropriate propositional hierarchies leading to empowerment of learners

    Science.gov (United States)

    Novak, Joseph D.

    2002-07-01

    The construction and reconstruction of meanings by learners requires that they actively seek to integrate new knowledge with knowledge already in their cognitive structure. Ausubel's assimilation theory of cognitive learning has been shown to be effective in guiding research and instructional design to facilitate meaningful learning (Ausubel, The psychology of meaningful verbal learning, New York: Grune and Stratton, 1963; Educational psychology: A cognitive view, New York: Holt, Rinehart and Winston, 1968; The acquisition and retention of knowledge, Dordrecht: Kluwer, 2000). Gowin's Vee heuristic has been employed effectively to aid teachers and students in understanding the constructed nature of knowledge (Gowin, Educating, Ithaca, NY: Cornell University Press, 1981). Situated learning occurs when learning is by rote or at a lower level of meaningful learning. Concept mapping has been used effectively to aid meaningful learning with resulting modification of student's knowledge structures. When these knowledge structures are limited or faulty in some way, they may be referred to as Limited or Inappropriate Propositional Hierarchies (LIPH's). Conceptual change, or more accurately conceptual reconstrution, requires meaningful learning to modify LIPH's. Collaborative group learning facilitates meaningful learning and new knowledge construction. World-wide economic changes are forcing major changes in business and industry placing a premium on the power and value of knowledge and new knowledge production. These changes require changes in school and university education that centers on the nature and power of meaningful learning. New computer tools are available to facilitate teaching activities targeted at modifying LIPH's, and aiding meaningful learning in general.

  3. Australian shellfish ecosystems: Past distribution, current status and future direction.

    Directory of Open Access Journals (Sweden)

    Chris L Gillies

    Full Text Available We review the status of marine shellfish ecosystems formed primarily by bivalves in Australia, including: identifying ecosystem-forming species, assessing their historical and current extent, causes for decline and past and present management. Fourteen species of bivalves were identified as developing complex, three-dimensional reef or bed ecosystems in intertidal and subtidal areas across tropical, subtropical and temperate Australia. A dramatic decline in the extent and condition of Australia's two most common shellfish ecosystems, developed by Saccostrea glomerata and Ostrea angasi oysters, occurred during the mid-1800s to early 1900s in concurrence with extensive harvesting for food and lime production, ecosystem modification, disease outbreaks and a decline in water quality. Out of 118 historical locations containing O. angasi-developed ecosystems, only one location still contains the ecosystem whilst only six locations are known to still contain S. glomerata-developed ecosystems out of 60 historical locations. Ecosystems developed by the introduced oyster Crasostrea gigas are likely to be increasing in extent, whilst data on the remaining 11 ecosystem-forming species are limited, preventing a detailed assessment of their current ecosystem-forming status. Our analysis identifies that current knowledge on extent, physical characteristics, biodiversity and ecosystem services of Australian shellfish ecosystems is extremely limited. Despite the limited information on shellfish ecosystems, a number of restoration projects have recently been initiated across Australia and we propose a number of existing government policies and conservation mechanisms, if enacted, would readily serve to support the future conservation and recovery of Australia's shellfish ecosystems.

  4. Australian shellfish ecosystems: Past distribution, current status and future direction

    Science.gov (United States)

    Gillies, Chris L.; McLeod, Ian M.; Alleway, Heidi K.; Cook, Peter; Crawford, Christine; Creighton, Colin; Diggles, Ben; Ford, John; Hamer, Paul; Heller-Wagner, Gideon; Lebrault, Emma; Le Port, Agnès; Russell, Kylie; Sheaves, Marcus; Warnock, Bryn

    2018-01-01

    We review the status of marine shellfish ecosystems formed primarily by bivalves in Australia, including: identifying ecosystem-forming species, assessing their historical and current extent, causes for decline and past and present management. Fourteen species of bivalves were identified as developing complex, three-dimensional reef or bed ecosystems in intertidal and subtidal areas across tropical, subtropical and temperate Australia. A dramatic decline in the extent and condition of Australia’s two most common shellfish ecosystems, developed by Saccostrea glomerata and Ostrea angasi oysters, occurred during the mid-1800s to early 1900s in concurrence with extensive harvesting for food and lime production, ecosystem modification, disease outbreaks and a decline in water quality. Out of 118 historical locations containing O. angasi-developed ecosystems, only one location still contains the ecosystem whilst only six locations are known to still contain S. glomerata-developed ecosystems out of 60 historical locations. Ecosystems developed by the introduced oyster Crasostrea gigas are likely to be increasing in extent, whilst data on the remaining 11 ecosystem-forming species are limited, preventing a detailed assessment of their current ecosystem-forming status. Our analysis identifies that current knowledge on extent, physical characteristics, biodiversity and ecosystem services of Australian shellfish ecosystems is extremely limited. Despite the limited information on shellfish ecosystems, a number of restoration projects have recently been initiated across Australia and we propose a number of existing government policies and conservation mechanisms, if enacted, would readily serve to support the future conservation and recovery of Australia’s shellfish ecosystems. PMID:29444143

  5. Utilization of health services in a resource-limited rural area in Kenya: Prevalence and associated household-level factors.

    Science.gov (United States)

    Ngugi, Anthony K; Agoi, Felix; Mahoney, Megan R; Lakhani, Amyn; Mang'ong'o, David; Nderitu, Esther; Armstrong, Robert; Macfarlane, Sarah

    2017-01-01

    Knowledge of utilization of health services and associated factors is important in planning and delivery of interventions to improve health services coverage. We determined the prevalence and factors associated with health services utilization in a rural area of Kenya. Our findings inform the local health management in development of appropriately targeted interventions. We used a cluster sample survey design and interviewed household key informants on history of illness for household members and health services utilization in the preceding month. We estimated prevalence and performed random effects logistic regression to determine the influence of individual and household level factors on decisions to utilize health services. 1230/6,440 (19.1%, 95% CI: 18.3%-20.2%) household members reported an illness. Of these, 76.7% (95% CI: 74.2%-79.0%) sought healthcare in a health facility. The majority (94%) of the respondents visited dispensary-level facilities and only 60.1% attended facilities within the study sub-counties. Of those that did not seek health services, 43% self-medicated by buying non-prescription drugs, 20% thought health services were too costly, and 10% indicated that the sickness was not serious enough to necessitate visiting a health facility. In the multivariate analyses, relationship to head of household was associated with utilization of health services. Relatives other than the nuclear family of the head of household were five times less likely to seek medical help (Odds Ratio 0.21 (95% CI: 0.05-0.87)). Dispensary level health facilities are the most commonly used by members of this community, and relations at the level of the household influence utilization of health services during an illness. These data enrich the perspective of the local health management to better plan the allocation of healthcare resources according to need and demand. The findings will also contribute in the development of community-level health coverage interventions that

  6. PhoB activates Escherichia coli O157:H7 virulence factors in response to inorganic phosphate limitation.

    Science.gov (United States)

    Chekabab, Samuel Mohammed; Jubelin, Grégory; Dozois, Charles M; Harel, Josée

    2014-01-01

    Enterohemorrhagic Escherichia coli (EHEC), an emerging food- and water-borne hazard, is highly pathogenic to humans. In the environment, EHEC must survive phosphate (Pi) limitation. The response to such Pi starvation is an induction of the Pho regulon including the Pst system that senses Pi variation. The interplay between the virulence of EHEC, Pho-Pst system and environmental Pi remains unknown. To understand the effects of Pi deprivation on the molecular mechanisms involved in EHEC survival and virulence under Pho regulon control, we undertook transcriptome profiling of the EDL933 wild-type strain grown under high Pi and low Pi conditions and its isogenic ΔphoB mutant grown in low Pi conditions. The differentially expressed genes included 1067 Pi-dependent genes and 603 PhoB-dependent genes. Of these 131 genes were both Pi and PhoB-dependent. Differentially expressed genes that were selected included those involved in Pi homeostasis, cellular metabolism, acid stress, oxidative stress and RpoS-dependent stress responses. Differentially expressed virulence systems included the locus of enterocyte effacement (LEE) encoding the type-3 secretion system (T3SS) and its effectors, as well as BP-933W prophage encoded Shiga toxin 2 genes. Moreover, PhoB directly regulated LEE and stx2 gene expression through binding to specific Pho boxes. However, in Pi-rich medium, constitutive activation of the Pho regulon decreased LEE gene expression and reduced adherence to HeLa cells. Together, these findings reveal that EHEC has evolved a sophisticated response to Pi limitation involving multiple biochemical strategies that contribute to its ability to respond to variations in environmental Pi and to coordinating the virulence response.

  7. PhoB activates Escherichia coli O157:H7 virulence factors in response to inorganic phosphate limitation.

    Directory of Open Access Journals (Sweden)

    Samuel Mohammed Chekabab

    Full Text Available Enterohemorrhagic Escherichia coli (EHEC, an emerging food- and water-borne hazard, is highly pathogenic to humans. In the environment, EHEC must survive phosphate (Pi limitation. The response to such Pi starvation is an induction of the Pho regulon including the Pst system that senses Pi variation. The interplay between the virulence of EHEC, Pho-Pst system and environmental Pi remains unknown. To understand the effects of Pi deprivation on the molecular mechanisms involved in EHEC survival and virulence under Pho regulon control, we undertook transcriptome profiling of the EDL933 wild-type strain grown under high Pi and low Pi conditions and its isogenic ΔphoB mutant grown in low Pi conditions. The differentially expressed genes included 1067 Pi-dependent genes and 603 PhoB-dependent genes. Of these 131 genes were both Pi and PhoB-dependent. Differentially expressed genes that were selected included those involved in Pi homeostasis, cellular metabolism, acid stress, oxidative stress and RpoS-dependent stress responses. Differentially expressed virulence systems included the locus of enterocyte effacement (LEE encoding the type-3 secretion system (T3SS and its effectors, as well as BP-933W prophage encoded Shiga toxin 2 genes. Moreover, PhoB directly regulated LEE and stx2 gene expression through binding to specific Pho boxes. However, in Pi-rich medium, constitutive activation of the Pho regulon decreased LEE gene expression and reduced adherence to HeLa cells. Together, these findings reveal that EHEC has evolved a sophisticated response to Pi limitation involving multiple biochemical strategies that contribute to its ability to respond to variations in environmental Pi and to coordinating the virulence response.

  8. Evaluation of the Accuracy and Related Factors of the Mechanical Torque-Limiting Device for Dental Implants

    Directory of Open Access Journals (Sweden)

    Mahmood Kazemi

    2013-01-01

    Full Text Available Objective: Accurate delivery of torque to implant screws is critical to generate ideal preload in the screw joint and to offer protection against screw loosening. Mechanical torque-limiting devices (MTLDs are available for this reason. In this study, the accuracy of one type of friction-style and two types of spring-style MTLDs at baseline, following fatigue conditions and sterilization processes were determined.Materials and Methods: Five unused MTLDs were selected from each of Straumann (ITI, Astra TECH and CWM systems. To measure the output of each MTLD, a digital torque gauge with a 3-jaw chuck was used to hold the driver. Force was applied to the MTLDs until either the friction styles released at a pre-calibrated torque value or the spring styles flexed to a pre-calibrated limit (target torque value. The peak torque value was recorded and the procedure was repeated 5 times for each MTLD. Then MTLDs were subjected to fatigue conditions at 500 and 1000 times and steam sterilization processes at 50 and 100 times and the peak torque value was recorded again at each stage.Results: Adjusted difference between measured torque values and target torque values differed significantly between stages for all 3 systems. Adjusted difference did not differ significantly between systems at all stages, but differed significantly between two different styles at baseline and 500 times fatigue stages.Conclusion: Straumann (ITI devices differed minimally from target torque values at all stages. MTLDs with Spring-style were significantly more accurate than Friction-style device in achieving their target torque values at baseline and 500 times fatigue

  9. Ecosystem quality in LCIA

    DEFF Research Database (Denmark)

    Woods, John S.; Damiani, Mattia; Fantke, Peter

    2017-01-01

    viewpoint and recommendations for future developments in LCIA related to the ecosystem quality area of protection (AoP). Through our recommendations, we aim to encourage LCIA developments that improve the usefulness and global acceptability of LCIA results. Methods: We analyze current ecosystem quality...... metrics and provide recommendations to the LCIA research community for achieving further developments towards comparable and more ecologically relevant metrics addressing ecosystem quality. Results and discussion: We recommend that LCIA development for ecosystem quality should tend towards species......—should be framed to facilitate their final expression in a single, aggregated metric. This would also improve comparability with other LCIA damage-level indicators. Furthermore, to allow for a broader inclusion of ecosystem quality perspectives, the development of an additional indicator related to ecosystem...

  10. Environmental metabarcoding reveals heterogeneous drivers of microbial eukaryote diversity in contrasting estuarine ecosystems

    Science.gov (United States)

    Lallias, Delphine; Hiddink, Jan G; Fonseca, Vera G; Gaspar, John M; Sung, Way; Neill, Simon P; Barnes, Natalie; Ferrero, Tim; Hall, Neil; Lambshead, P John D; Packer, Margaret; Thomas, W Kelley; Creer, Simon

    2015-01-01

    Assessing how natural environmental drivers affect biodiversity underpins our understanding of the relationships between complex biotic and ecological factors in natural ecosystems. Of all ecosystems, anthropogenically important estuaries represent a ‘melting pot' of environmental stressors, typified by extreme salinity variations and associated biological complexity. Although existing models attempt to predict macroorganismal diversity over estuarine salinity gradients, attempts to model microbial biodiversity are limited for eukaryotes. Although diatoms commonly feature as bioindicator species, additional microbial eukaryotes represent a huge resource for assessing ecosystem health. Of these, meiofaunal communities may represent the optimal compromise between functional diversity that can be assessed using morphology and phenotype–environment interactions as compared with smaller life fractions. Here, using 454 Roche sequencing of the 18S nSSU barcode we investigate which of the local natural drivers are most strongly associated with microbial metazoan and sampled protist diversity across the full salinity gradient of the estuarine ecosystem. In order to investigate potential variation at the ecosystem scale, we compare two geographically proximate estuaries (Thames and Mersey, UK) with contrasting histories of anthropogenic stress. The data show that although community turnover is likely to be predictable, taxa are likely to respond to different environmental drivers and, in particular, hydrodynamics, salinity range and granulometry, according to varied life-history characteristics. At the ecosystem level, communities exhibited patterns of estuary-specific similarity within different salinity range habitats, highlighting the environmental sequencing biomonitoring potential of meiofauna, dispersal effects or both. PMID:25423027

  11. The pre-rRNA processing factor DEF is rate limiting for the pathogenesis of MYCN-driven neuroblastoma.

    Science.gov (United States)

    Tao, T; Sondalle, S B; Shi, H; Zhu, S; Perez-Atayde, A R; Peng, J; Baserga, S J; Look, A T

    2017-07-06

    The nucleolar factor, digestive organ expansion factor (DEF), has a key role in ribosome biogenesis, functioning in pre-ribosomal RNA (pre-rRNA) processing as a component of the small ribosomal subunit (SSU) processome. Here we show that the peripheral sympathetic nervous system (PSNS) is very underdeveloped in def-deficient zebrafish, and that def haploinsufficiency significantly decreases disease penetrance and tumor growth rate in a MYCN-driven transgenic zebrafish model of neuroblastoma that arises in the PSNS. Consistent with these findings, DEF is highly expressed in human neuroblastoma, and its depletion in human neuroblastoma cell lines induces apoptosis. Interestingly, overexpression of MYCN in zebrafish and in human neuroblastoma cells results in the appearance of intermediate pre-rRNAs species that reflect the processing of pre-rRNAs through Pathway 2, a pathway that processes pre-rRNAs in a different temporal order than the more often used Pathway 1. Our results indicate that DEF and possibly other components of the SSU processome provide a novel site of vulnerability in neuroblastoma cells that could be exploited for targeted therapy.

  12. Evolutionary diversification in stickleback affects ecosystem functioning.

    Science.gov (United States)

    Harmon, Luke J; Matthews, Blake; Des Roches, Simone; Chase, Jonathan M; Shurin, Jonathan B; Schluter, Dolph

    2009-04-30

    Explaining the ecological causes of evolutionary diversification is a major focus of biology, but surprisingly little has been said about the effects of evolutionary diversification on ecosystems. The number of species in an ecosystem and their traits are key predictors of many ecosystem-level processes, such as rates of productivity, biomass sequestration and decomposition. Here we demonstrate short-term ecosystem-level effects of adaptive radiation in the threespine stickleback (Gasterosteus aculeatus) over the past 10,000 years. These fish have undergone recent parallel diversification in several lakes in coastal British Columbia, resulting in the formation of two specialized species (benthic and limnetic) from a generalist ancestor. Using a mesocosm experiment, we demonstrate that this diversification has strong effects on ecosystems, affecting prey community structure, total primary production, and the nature of dissolved organic materials that regulate the spectral properties of light transmission in the system. However, these ecosystem effects do not simply increase in their relative strength with increasing specialization and species richness; instead, they reflect the complex and indirect consequences of ecosystem engineering by sticklebacks. It is well known that ecological factors influence adaptive radiation. We demonstrate that adaptive radiation, even over short timescales, can have profound effects on ecosystems.

  13. Elucidation of sigma factor-associated networks in Pseudomonas aeruginosa reveals a modular architecture with limited and function-specific crosstalk.

    Directory of Open Access Journals (Sweden)

    Sebastian Schulz

    2015-03-01

    Full Text Available Sigma factors are essential global regulators of transcription initiation in bacteria which confer promoter recognition specificity to the RNA polymerase core enzyme. They provide effective mechanisms for simultaneously regulating expression of large numbers of genes in response to challenging conditions, and their presence has been linked to bacterial virulence and pathogenicity. In this study, we constructed nine his-tagged sigma factor expressing and/or deletion mutant strains in the opportunistic pathogen Pseudomonas aeruginosa. To uncover the direct and indirect sigma factor regulons, we performed mRNA profiling, as well as chromatin immunoprecipitation coupled to high-throughput sequencing. We furthermore elucidated the de novo binding motif of each sigma factor, and validated the RNA- and ChIP-seq results by global motif searches in the proximity of transcriptional start sites (TSS. Our integrated approach revealed a highly modular network architecture which is composed of insulated functional sigma factor modules. Analysis of the interconnectivity of the various sigma factor networks uncovered a limited, but highly function-specific, crosstalk which orchestrates complex cellular processes. Our data indicate that the modular structure of sigma factor networks enables P. aeruginosa to function adequately in its environment and at the same time is exploited to build up higher-level functions by specific interconnections that are dominated by a participation of RpoN.

  14. Lack of infrastructure, social and cultural factors limit physical activity among patients with type 2 diabetes in rural Sri Lanka, a qualitative study.

    Science.gov (United States)

    Medagama, Arjuna; Galgomuwa, Manoj

    2018-01-01

    South Asians have high prevalence of diabetes, increased cardiovascular risk and low levels of physical activity (PA). Reasons for low levels of PA have not previously been explored among Asians living within their endogenous environment. This qualitative study was performed to explore the contextual reasons that limited PA among type 2 diabetic patients living in a rural community. Purposeful sampling recruited 40 participants with long standing type 2 diabetes for this qualitative study. Semi-structered questions utilising in-depth interviews were used to collect data on PA patterns, barriers to PA and factors that would facilitate PA. The interviews were digitally recorded and transcribed. Data were analyzed using a framework approach. The sample consisted of 11 males and 29 females. Mean age was 55.4 (SD 8.9) years. The mean duration of diabetes in the study population was 8.5 (SD 6.8) years. Inability to differentitate household and daily activities from PA emerged as a recurring theme. Most did not have a clear understanding of the type or duration of PA that they should perform. Health related issues, lifestyle and time management, envronmental and social factors like social embarrassment, prioritizing household activities over PA were important factors that limited PA. Most stated that the concept of exercising was alien to their culture and lifestyle. Culturally appropriate programmes that strengthen health education and empower communities to overcome socio-economic barriers that limit PA should be implemented to better manage diabetes among rural Sri Lankan diabetic patients.

  15. Dynamic belowground ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Harris, W. F.; Santantonio, D.; McGinty, D.

    1979-01-01

    Roots comprise the primary interface between plant and soil for uptake of water and nutrients. Much is known about the biochemistry, cell physiology and membrane physics associated with these important processes. In this paper we discuss the role of the belowground ecosystem, especially the autotrophic root component, in the structure and function of forest ecosystems. Beyond recognizing roles of anchoring terrestrial plants and uptake of water and nutrients, this component of the forest has been largely neglected in an ecosystem context. In order to focus discussion on the properties of the belowground ecosystem, we use the term rhizosphere to include roots, mycorrhizae, microbes, and rhizophagus invertebrates.

  16. Plant size and abiotic factors determine the intra-specific variation in the multi-stemmed architecture of Prunus lusitanica in the Northeast limit of its global distribution

    Directory of Open Access Journals (Sweden)

    A. Muñoz Costa

    2013-12-01

    Full Text Available Aim of study: The present work provides novel insights on factors (either intrinsic or extrinsic that trigger sprouting in woody species living at range margins. We aim to explain the inter-individual variability in the multi-stemmed architecture of Prunus lusitanica L., an Iberian evergreen relict tree related to the Tertiary flora.Area of study: Northeastern Mediterranean mountains of the Iberian Peninsula, the Northeast limit of the global distribution of the species.Material and Methods: We gathered data on two modes of vegetative reproduction, basal and layering sprouts, in 288 clumps of Prunus lusitanica from four populations. We modeled and analyzed the effect of environmental factors (topography, canopy cover, soil moisture and disturbances and plant size (diameter at breast height on sprouting by means of Generalized Linear Model and other statistical approaches.Main results: Plant size arises as the principal factor to explain the variability of the numbers of both types of sprouts yet it is not a trigger factor. Natural and anthropogenic disturbances promote basal and layering shoots, while tree canopy is mainly relevant for basal shoots, and slope and soil moisture are significant factors for layering shoots.Research highlights: The multi-stemmed architecture of P. lusitanica at the Northeastern limit of its worldwide distribution is triggered by local environmental factors and disturbances. Each external factor shows different levels of influence on the variability and type of vegetative reproduction yet the intensity of the response is driven by the size of the largest trunk of each clump.Key words: vegetative reproduction; sprouting; disturbances; woody plants; relict tree; subtropical; Iberian Peninsula.

  17. Scaling of graphene field-effect transistors supported on hexagonal boron nitride: radio-frequency stability as a limiting factor

    Science.gov (United States)

    Feijoo, Pedro C.; Pasadas, Francisco; Iglesias, José M.; Martín, María J.; Rengel, Raúl; Li, Changfeng; Kim, Wonjae; Riikonen, Juha; Lipsanen, Harri; Jiménez, David

    2017-12-01

    The quality of graphene in nanodevices has increased hugely thanks to the use of hexagonal boron nitride as a supporting layer. This paper studies to which extent hBN together with channel length scaling can be exploited in graphene field-effect transistors (GFETs) to get a competitive radio-frequency (RF) performance. Carrier mobility and saturation velocity were obtained from an ensemble Monte Carlo simulator that accounted for the relevant scattering mechanisms (intrinsic phonons, scattering with impurities and defects, etc). This information is fed into a self-consistent simulator, which solves the drift-diffusion equation coupled with the two-dimensional Poisson’s equation to take full account of short channel effects. Simulated GFET characteristics were benchmarked against experimental data from our fabricated devices. Our simulations show that scalability is supposed to bring to RF performance an improvement that is, however, highly limited by instability. Despite the possibility of a lower performance, a careful choice of the bias point can avoid instability. Nevertheless, maximum oscillation frequencies are still achievable in the THz region for channel lengths of a few hundreds of nanometers.

  18. Scaling of graphene field-effect transistors supported on hexagonal boron nitride: radio-frequency stability as a limiting factor.

    Science.gov (United States)

    Feijoo, Pedro C; Pasadas, Francisco; Iglesias, José M; Martín, María J; Rengel, Raúl; Li, Changfeng; Kim, Wonjae; Riikonen, Juha; Lipsanen, Harri; Jiménez, David

    2017-12-01

    The quality of graphene in nanodevices has increased hugely thanks to the use of hexagonal boron nitride as a supporting layer. This paper studies to which extent hBN together with channel length scaling can be exploited in graphene field-effect transistors (GFETs) to get a competitive radio-frequency (RF) performance. Carrier mobility and saturation velocity were obtained from an ensemble Monte Carlo simulator that accounted for the relevant scattering mechanisms (intrinsic phonons, scattering with impurities and defects, etc). This information is fed into a self-consistent simulator, which solves the drift-diffusion equation coupled with the two-dimensional Poisson's equation to take full account of short channel effects. Simulated GFET characteristics were benchmarked against experimental data from our fabricated devices. Our simulations show that scalability is supposed to bring to RF performance an improvement that is, however, highly limited by instability. Despite the possibility of a lower performance, a careful choice of the bias point can avoid instability. Nevertheless, maximum oscillation frequencies are still achievable in the THz region for channel lengths of a few hundreds of nanometers.

  19. Amino acids supply in culture media is not a limiting factor in the matrix synthesis of engineered cartilage tissue

    Science.gov (United States)

    Ng, K. W.; DeFrancis, J. G.; Kugler, L. E.; Kelly, T.-A. N.; Ho, M. M.; O’Conor, C. J.; Ateshian, G. A.; Hung, C. T.

    2013-01-01

    Summary Increased amino acid supplementation (0.5×, 1.0×, and 5.0× recommended concentrations or additional proline) was hypothesized to increase the collagen content in engineered cartilage. No significant differences were found between groups in matrix content or dynamic modulus. Control constructs possessed the highest compressive Young’s modulus on day 42. On day 42, compared to controls, decreased type II collagen was found with 0.5×, 1.0×, and 5.0× supplementation and significantly increased DNA content found in 1.0× and 5.0×. No effects were observed on these measures with added proline. These results lead us to reject our hypothesis and indicate that the low collagen synthesis in engineered cartilage is not due to a limited supply of amino acids in media but may require a further stimulatory signal. The results of this study also highlight the impact that culture environment can play on the development of engineered cartilage. PMID:17713744

  20. KANSL1 variation is not a major contributing factor in self-limited focal epilepsy syndromes of childhood.

    Directory of Open Access Journals (Sweden)

    Kenneth A Myers

    Full Text Available KANSL1 haploinsufficiency causes Koolen-de Vries syndrome (KdVS, characterized by dysmorphic features and intellectual disability; amiable personality, congenital malformations and seizures also commonly occur. The epilepsy phenotypic spectrum in KdVS is broad, but most individuals have focal seizures with some having a phenotype resembling the self-limited focal epilepsies of childhood (SFEC. We hypothesized that variants in KANSL1 contribute to pathogenesis of SFEC.We screened KANSL1 for single nucleotide variants in 90 patients with SFEC. We then screened a cohort of 208 patients with two specific SFEC syndromes, childhood epilepsy with centrotemporal spikes (CECTS and atypical childhood epilepsy with centrotemporal spikes (ACECTS for KANSL1 variants. The second cohort was also used to evaluate minor allelic variants that appeared overrepresented in the initial cohort.One variant, p.Lys104Thr, was predicted damaging and appeared overrepresented in our 90-patient cohort compared to Genome Aggregation Database (gnomAD allele frequency (0.217 to 0.116, with no homozygotes in gnomAD. However, there was no difference in p.Lys104Thr allele frequency in the follow-up CECTS/ACECTS cohort and controls. Four rare KANSL1 variants of uncertain significance were identified in the CECTS/ACECTS cohort.Our data do not support a major role for KANSL1 variants in pathogenesis of SFEC.

  1. Neighbourhood-scale urban forest ecosystem classification.

    Science.gov (United States)

    Steenberg, James W N; Millward, Andrew A; Duinker, Peter N; Nowak, David J; Robinson, Pamela J

    2015-11-01

    Urban forests are now recognized as essential components of sustainable cities, but there remains uncertainty concerning how to stratify and classify urban landscapes into units of ecological significance at spatial scales appropriate for management. Ecosystem classification is an approach that entails quantifying the social and ecological processes that shape ecosystem conditions into logical and relatively homogeneous management units, making the potential for ecosystem-based decision support available to urban planners. The purpose of this study is to develop and propose a framework for urban forest ecosystem classification (UFEC). The multifactor framework integrates 12 ecosystem components that characterize the biophysical landscape, built environment, and human population. This framework is then applied at the neighbourhood scale in Toronto, Canada, using hierarchical cluster analysis. The analysis used 27 spatially-explicit variables to quantify the ecosystem components in Toronto. Twelve ecosystem classes were identified in this UFEC application. Across the ecosystem classes, tree canopy cover was positively related to economic wealth, especially income. However, education levels and homeownership were occasionally inconsistent with the expected positive relationship with canopy cover. Open green space and stocking had variable relationships with economic wealth and were more closely related to population density, building intensity, and land use. The UFEC can provide ecosystem-based information for greening initiatives, tree planting, and the maintenance of the existing canopy. Moreover, its use has the potential to inform the prioritization of limited municipal resources according to ecological conditions and to concerns of social equity in the access to nature and distribution of ecosystem service supply. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Seasonality in marine ecosystems: Peruvian seabirds, anchovy, and oceanographic conditions.

    Science.gov (United States)

    Passuni, Giannina; Barbraud, Christophe; Chaigneau, Alexis; Demarcq, Hervé; Ledesma, Jesus; Bertrand, Arnaud; Castillo, Ramiro; Perea, Angel; Mori, Julio; Viblanc, Vincent A; Torres-MaitaA, Jose; Bertrand, Sophie

    2016-01-01

    In fluctuating environments, matching breeding timing to periods of high resource availability is crucial for the fitness of many vertebrate species, and may have major consequences on population health. Yet, our understanding of the proximate environmental cues driving seasonal breeding is limited. This is particularly the case in marine ecosystems, where key environmental factors and prey abundance and availability are seldom quantified. The Northern Humboldt Current System (NHCS) is a highly productive, low-latitude ecosystem of moderate seasonality. In this ecosystem, three tropical seabird species (the Guanay Cormorant Phalacrocorax bougainvillii, the Peruvian Booby Sula variegata, and the Peruvian Pelican Pelecanus thagus) live in sympatry and prey almost exclusively on anchovy, Engraulis ringens. From January 2003 to December 2012, we monitored 31 breeding sites along the Peruvian coast to investigate the breeding cycle of these species. We tested for relationships between breeding timing, oceanographic conditions, and prey availability using occupancy models. We found that all three seabird species exhibited seasonal breeding patterns, with marked interspecific differences. Whereas breeding mainly started during the austral winter/early spring and ended in summer/early fall, this pattern was stronger in boobies and pelicans than in cormorants. Breeding onset mainly occurred when upwelling was intense but ecosystem productivity was below its annual maxima, and when anchovy were less available and in poor physiological condition. Conversely, the abundance and availability of anchovy improved during chick rearing and peaked around the time of fledging. These results suggest that breeding timing is adjusted so that fledging may occur under optimal environmental conditions, rather than being constrained by nutritional requirements during egg laying. Adjusting breeding time so that fledglings meet optimal conditions at independence is unique compared with other

  3. BUSINESS ECOSYSTEMS VS BUSINESS DIGITAL ECOSYSTEMS

    Directory of Open Access Journals (Sweden)

    Marinela Lazarica

    2006-05-01

    Full Text Available E-business is often described as the small organisations’ gateway to global business and markets. The adoption of Internet-based technologies for e-business is a continuous process, with sequential steps of evolution. The latter step in the adoption of Internet-based technologies for business, where the business services and the software components are supported by a pervasive software environment, which shows an evolutionary and self-organising behaviour are named digital business ecosystems. The digital business ecosystems are characterized by intelligent software components and services, knowledge transfer, interactive training frameworks and integration of business processes and e-government models.

  4. Fire as a natural and human factor shaping the Mediterranean Ecosystems. The Montgó forest fire and the teaching for the Geograns (older than 55) students

    Science.gov (United States)

    Cerdà, Artemi; González Pelayo, Óscar; Mataix-Solera, Jorge; Arcenegui, Victoria; Jordán, Antonio; Úbeda, Xavier; Pereira, Paulo

    2015-04-01

    Cerdà and Civera (2012); Fernández Raga et al., (2013) and Cerdà et al., (2014) show that teaching Earth Sciences to students older than 55 is a new challenge for the universities of developed countries due to the higher life expectancy and the arrival of new students and teaching programs to the academy. Fire, due to the background of many of our students, is one of those topics that need more attention when teaching to students older than 55. Most of them see the fire as the enemy and not as a part of the natural and human ecosystems. The view of the scientists is based in the scientific method, and they see the fire as part of the ecosystems and the human societies (Roebroeks and Villa, 2011; Archibald et al., 2012; Berna et al, 2012; Romme et al., 2012; Zumbrunnen et al., 2012). Moreover, the studies developed on the soils, vegetation and hydrological response of fire affected land, show that the fire disturbance use to be short and the ecosystems return to the pre-fire period after a window of disturbance (Cerdà and Lasanta, 2005; Doerr and Cerdà, 2005; Lasanta and Cerdà, 2005; Granjed et al., 2011; Pérez Cabello et al., 2012; Bodí et al., 2013; Guenon et al., 2013; León et al., 2013: Pereira et al., 2013; Pereira et al., 2015; Prats et al., 2015), and this is related to the policies applied in different countries (Carreiras et al., 2014). More recent advances in the impact of fire on soils can be found in Bento-Gonçalves et al. (2012) This research show the different strategies that we apply to explain the students older than 55 to understand the natural processes that are involved in nature due to the fire. The lectures are developed at the lectures room as an introduction about the fire in the Earth System and how the fire modify the soils, the water resources and change the vegetation cover, and 10 hours of field work in an recently fire affected land. The second part of the course, 10 hours in the field, will be done in February during a visit

  5. B cell-derived transforming growth factor-β1 expression limits the induction phase of autoimmune neuroinflammation.

    Science.gov (United States)

    Bjarnadóttir, Kristbjörg; Benkhoucha, Mahdia; Merkler, Doron; Weber, Martin S; Payne, Natalie L; Bernard, Claude C A; Molnarfi, Nicolas; Lalive, Patrice H

    2016-10-06

    Studies in experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS), have shown that regulatory B cells modulate the course of the disease via the production of suppressive cytokines. While data indicate a role for transforming growth factor (TGF)-β1 expression in regulatory B cell functions, this mechanism has not yet been tested in autoimmune neuroinflammation. Transgenic mice deficient for TGF-β1 expression in B cells (B-TGF-β1 -/- ) were tested in EAE induced by recombinant mouse myelin oligodendrocyte glycoprotein (rmMOG). In this model, B-TGF-β1 -/- mice showed an earlier onset of neurologic impairment compared to their littermate controls. Exacerbated EAE susceptibility in B-TGF-β1 -/- mice was associated with augmented CNS T helper (Th)1/17 responses. Moreover, selective B cell TGF-β1-deficiency increased the frequencies and activation of myeloid dendritic cells, potent professional antigen-presenting cells (APCs), suggesting that B cell-derived TGF-β1 can constrain Th1/17 responses through inhibition of APC activity. Collectively our data suggest that B cells can down-regulate the function of APCs, and in turn encephalitogenic Th1/17 responses, via TGF-β1, findings that may be relevant to B cell-targeted therapies.

  6. The Transcription Factor T-bet Limits Amplification of Type I IFN Transcriptome and Circuitry in T Helper 1 Cells.

    Science.gov (United States)

    Iwata, Shigeru; Mikami, Yohei; Sun, Hong-Wei; Brooks, Stephen R; Jankovic, Dragana; Hirahara, Kiyoshi; Onodera, Atsushi; Shih, Han-Yu; Kawabe, Takeshi; Jiang, Kan; Nakayama, Toshinori; Sher, Alan; O'Shea, John J; Davis, Fred P; Kanno, Yuka

    2017-06-20

    Host defense requires the specification of CD4 + helper T (Th) cells into distinct fates, including Th1 cells that preferentially produce interferon-γ (IFN-γ). IFN-γ, a member of a large family of anti-pathogenic and anti-tumor IFNs, induces T-bet, a lineage-defining transcription factor for Th1 cells, which in turn supports IFN-γ production in a feed-forward manner. Herein, we show that a cell-intrinsic role of T-bet influences how T cells perceive their secreted product in the environment. In the absence of T-bet, IFN-γ aberrantly induced a type I IFN transcriptomic program. T-bet preferentially repressed genes and pathways ordinarily activated by type I IFNs to ensure that its transcriptional response did not evoke an aberrant amplification of type I IFN signaling circuitry, otherwise triggered by its own product. Thus, in addition to promoting Th1 effector commitment, T-bet acts as a repressor in differentiated Th1 cells to prevent abberant autocrine type I IFN and downstream signaling. Published by Elsevier Inc.

  7. Factors modulating cottongrass seedling growth stimulation to enhanced nitrogen and carbon dioxide: compensatory tradeoffs in leaf dynamics and allocation to meet potassium-limited growth.

    Science.gov (United States)

    Siegenthaler, Andy; Buttler, Alexandre; Grosvernier, Philippe; Gobat, Jean-Michel; Nilsson, Mats B; Mitchell, Edward A D

    2013-02-01

    Eriophorum vaginatum is a characteristic species of northern peatlands and a keystone plant for cutover bog restoration. Understanding the factors affecting E. vaginatum seedling establishment (i.e. growth dynamics and allocation) under global change has practical implications for the management of abandoned mined bogs and restoration of their C-sequestration function. We studied the responses of leaf dynamics, above- and belowground biomass production of establishing seedlings to elevated CO(2) and N. We hypothesised that nutrient factors such as limitation shifts or dilutions would modulate growth stimulation. Elevated CO(2) did not affect biomass, but increased the number of young leaves in spring (+400 %), and the plant vitality (i.e. number of green leaves/total number of leaves) (+3 %), both of which were negatively correlated to [K(+)] in surface porewater, suggesting a K-limited production of young leaves. Nutrient ratios in green leaves indicated either N and K co-limitation or K limitation. N addition enhanced the number of tillers (+38 %), green leaves (+18 %), aboveground and belowground biomass (+99, +61 %), leaf mass-to-length ratio (+28 %), and reduced the leaf turnover (-32 %). N addition enhanced N availability and decreased [K(+)] in spring surface porewater. Increased tiller and leaf production in July were associated with a doubling in [K(+)] in surface porewater suggesting that under enhanced N production is K driven. Both experiments illustrate the importance of tradeoffs in E. vaginatum growth between: (1) producing tillers and generating new leaves, (2) maintaining adult leaves and initiating new ones, and (3) investing in basal parts (corms) for storage or in root growth for greater K uptake. The K concentration in surface porewater is thus the single most important factor controlling the growth of E. vaginatum seedlings in the regeneration of selected cutover bogs.

  8. Reinforcement of the Gas Barrier Properties of Polyethylene and Polyamide Through the Nanocomposite Approach: Key Factors and Limitations

    Directory of Open Access Journals (Sweden)

    Picard E.

    2015-02-01

    Full Text Available In this study, polyamide 6 (PA6 and polyethylene (PE nanocomposites were prepared from melt blending and a detailed characterization of the nanocomposite morphology and gas barrier properties was performed. The choice of the organoclay was adapted to each polymer matrix. Exfoliated morphology and improved gas transport properties were obtained by melt mixing the polar PA6 matrix and the organoclay, whereas a microcomposite with poor barrier properties was formed from the binary PE/organomodified clay mixture. Different modified polyethylenes were examined as compatibilizers for the polyethylene/organoclay system. The effect of compatibilizer molar mass, polarity and content was investigated on the clay dispersion and on the gas barrier properties. The optimal compatibilizer to clay weight ratio was found to be equal to 4 whatever the compatibilizer. However, a high degree of clay delamination was obtained with the high molar mass compatibilizer whereas highly swollen clay aggregates resulted from the incorporation of the low molar mass interfacial agents. Contrary to the PA based system, the barrier properties of PE nanocomposites were not directly related to the clay dispersion state but resulted also from the matrix/clay interfacial interactions. Oxidized wax was identified as a very promising interfacial agent and a step by step study was performed to optimize the gas transport properties of the systems based on PE, oxidized wax and organoclay. In particular, an interesting combination of oxidized wax and high molar mass maleic anhydride grafted polyethylene allowing dividing the gas permeability by a factor 2 in comparison with neat PE was proposed.

  9. High Biodiversity of Green Infrastructure Does Not Contribute to Recreational Ecosystem Services

    Directory of Open Access Journals (Sweden)

    Daria Sikorska

    2017-02-01

    Full Text Available Urban lakes, especially those of natural origin, provide ecosystem services, recreation being one of the most important and highly valued by city dwellers. Fulfilling the needs of city residents to relax and have contact with nature has become a priority in urbanized areas and has been proven to positively affect people’s health and well-being. The recreational potential of water bodies was identified to be the most important aspect of ecosystem services to the residents of the neighboring areas. An assessment of recreational ecosystem services (RES provisioning to society based on the real time spent by the citizens and housing values in the urban–rural gradient revealed that the economic benefits of lakes differ in urbanized, suburban and rural landscapes. The growth of cities has led to an increased population density in the surroundings of ecologically valuable areas, resulting in higher pressure from visitors seeking recreational areas. Along with urbanization, the impoverishment of ecosystem functions takes place, limiting their capability to provide ecosystem services. In this work, the provisioning of recreational ecosystem services of 28 floodplain lakes located along the urban–rural gradient of the Warsaw agglomeration was assessed. The relationship between the ecological value of the water bodies, measured using naturalness indices, and the recreational ecosystem services they can provide was assessed. The results showed that the floodplain lakes located along the urban–rural gradient are of great importance to the citizens due to their recreational potential. The provisioning of recreational ecosystem services is poorly connected with the ecological characteristics of the floodplain lakes. Only hemeroby was significantly correlated with provisioning, and there was no relationship with factors such as naturalness of vegetation or water quality, demonstrating that public preference was not generally influenced by high

  10. Mobility Limitations and Fall-Related Factors Contribute to the Reduced Health-Related Quality of Life in Older Adults With Chronic Musculoskeletal Pain.

    Science.gov (United States)

    Stubbs, Brendon; Schofield, Pat; Patchay, Sandhi

    2016-01-01

    To investigate (1) the prevalence of chronic musculoskeletal pain (CMP) among a sample of community-dwelling older adults and (2) health-related quality of life (HRQOL) in people with CMP, particularly the association with mobility limitations and falls-related factors. Overall, 295 (response rate 73.5%) community-dwelling older adults were recruited across 10 sites. CMP was assessed using recognized criteria. In the sample of people with CMP, a hierarchical multiple regression analysis was conducted with HRQOL as the dependent variable and a number of independent variables were then inserted into the model. After controlling for demographic and medical variables, mobility (timed up and go (TUG), walking aid use, sedentary behavior) and fall-related factors (falls history, balance confidence, concerns about consequences of falling) were inserted into the model at the second step and changes in adjusted R(2) noted. Within our sample of older adults, 52% had CMP (154/295). Compared to the group without CMP of similar age (n = 141), those with CMP had reduced HRQOL and profound mobility limitations and more falls risk factors (P falls explanatory variables increased the variance explained within HRQOL from 14% to 36% (adjusted R(2) change 20%) in those with CMP. Sedentary behavior, pain interference, concerns about the consequences of falling, falls history, TUG scores, and balance confidence all remained significant predictors of HRQOL in the fully adjusted model in the CMP sample. Older adults with CMP have pronounced mobility limitations and increased falls risk factors, and these are associated with a marked reduction in HRQOL. Future prospective research is required to build on this cross-sectional study. © 2014 World Institute of Pain.

  11. Belowground ecosystems [chapter 9

    Science.gov (United States)

    Carole Coe Klopatek

    1995-01-01

    The USDA Forest Service defined ecosystem management as "an ecological approach to achieve multiple-use management of national forests and grasslands by blending the needs of people and environmental values in such a way that national forests and grasslands represent diverse, healthy, productive, and sustainable ecosystems" (June 4, 1992, letter from Chief FS...

  12. Ecosystem Management and Sustainability

    Science.gov (United States)

    J.D. Peine; B.L. Jacobs; K.E. Franzreb; M.R. Stevens

    2011-01-01

    Ecosystem management (EM) promotes an integrated approach to environmental issues; its central goal is the protection of entire ecosystems. By focusing on an interdisciplinary solution to environmental challenges, EM can help to synthesize societal, economic scientific, and governmental goals. Furthermore, as EM becomes part of the foundation of environmental...

  13. Radionuclides in terrestrial ecosystems

    International Nuclear Information System (INIS)

    Bocock, K.L.

    1981-01-01

    This report summarizes information on the distribution and movement of radionuclides in semi-natural terrestrial ecosystems in north-west England with particular emphasis on inputs to, and outputs from ecosystems; on plant and soil aspects; and on radionuclides in fallout and in discharges by the nuclear industry. (author)

  14. TH-EF-204-03: Determination of Small Field Output Factors, Advantages and Limitations of Monte Carlo Simulation

    International Nuclear Information System (INIS)

    Vaque, J. Puxeu

    2016-01-01

    dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research

  15. Mapping cultural ecosystem services:

    DEFF Research Database (Denmark)

    Paracchini, Maria Luisa; Zulian, Grazia; Kopperoinen, Leena

    2014-01-01

    Research on ecosystem services mapping and valuing has increased significantly in recent years. However, compared to provisioning and regulating services, cultural ecosystem services have not yet been fully integrated into operational frameworks. One reason for this is that transdisciplinarity...... surveys are a main source of information. Among cultural ecosystem services, assessment of outdoor recreation can be based on a large pool of literature developed mostly in social and medical science, and landscape and ecology studies. This paper presents a methodology to include recreation...... in the conceptual framework for EU wide ecosystem assessments (Maes et al., 2013), which couples existing approaches for recreation management at country level with behavioural data derived from surveys, and population distribution data. The proposed framework is based on three components: the ecosystem function...

  16. Effectiveness of enforcement levels of speed limit and drink driving laws and associated factors – Exploratory empirical analysis using a bivariate ordered probit model

    Directory of Open Access Journals (Sweden)

    Behram Wali

    2017-06-01

    Full Text Available The contemporary traffic safety research comprises little information on quantifying the simultaneous association between drink driving and speeding among fatally injured drivers. Potential correlation between driver's drink driving and speeding behavior poses a substantial methodological concern which needs investigation. This study therefore focused on investigating the simultaneous impact of socioeconomic factors, fatalities, vehicle ownership, health services and highway agency road safety policies on enforcement levels of speed limit and drink driving laws. The effectiveness of enforcement levels of speed limit and drink driving laws has been investigated through development of bivariate ordered probit model using data extricated from WHO's global status report on road safety in 2013. The consistent and intuitive parameter estimates along with statistically significant correlation between response outcomes validates the statistical supremacy of bivariate ordered probit model. The results revealed that fatalities per thousand registered vehicles, hospital beds per hundred thousand population and road safety policies are associated with a likely medium or high effectiveness of enforcement levels of speed limit and drink driving laws, respectively. Also, the model encapsulates the effect of several other agency related variables and socio-economic status on the response outcomes. Marginal effects are reported for analyzing the impact of such factors on intermediate categories of response outcomes. The results of this study are expected to provide necessary insights to elemental enforcement programs. Also, marginal effects of explanatory variables may provide useful directions for formulating effective policy countermeasures for overcoming driver's speeding and drink driving behavior.

  17. Democracy as a Limiting Factor for Politicised Cultural Populism in Malawi Demokratie und politisierter Kulturpopulismus in Malawi

    Directory of Open Access Journals (Sweden)

    Reuben Makayiko Chirambo

    2009-01-01

    Full Text Available Though Malawian democracy could still be described as in transition from authoritarianism, it has enabled an atmosphere for critical debate of and dissent against seemingly popular opinions, which was not possible during the authoritarian rule of former life president, Dr. H. K. Banda, 1964-1994. This article examines politicised cultural populism in Malawi under the dictatorship and democracy in comparative terms. President Banda, as a political populist, appropriated culture to legitimate and validate his political power as well as to cultivate popular support from the majority of ordinary people. Following reforms towards democracy since 1992, his successors have also tended towards populist politics by similarly appropriating culture and cultural activities, among other means, to cultivate popular support from mostly ordinary people for their regimes. Such politicised cultural populism involves adopting traditional roles, cultural symbols and images of power such as praise-titles, and participating in cultural activities such as traditional dances. This article examines the efforts of President Bingu wa Mutharika in the democratic dispensation to appropriate cultural artefacts used by Banda during a dictatorship in order to cultivate popular support for his regime. The article argues that Bingu’s efforts at politicised cultural populism are constrained, among other factors, by the nature and climate of democratic politics mainly because democracy, unlike a dictatorship, enables critical debate and the questioning of political leader’s behaviour and their motives. Auch wenn die Demokratie in Malawi sich immer noch in einem Übergangsstadium befindet, ist inzwischen eine Atmosphäre entstanden, in der eine kritische Debatte und das Äußern unpopulärer Meinungen möglich sind, was in den Jahren 1964-1994 unter dem früheren Präsidenten auf Lebenszeit, Dr. H. K. Banda, nicht denkbar war. Der Autor vergleicht die Nutzung von Elementen

  18. Ecosystem approach in education

    Science.gov (United States)

    Nabiullin, Iskander

    2017-04-01

    Environmental education is a base for sustainable development. Therefore, in our school we pay great attention to environmental education. Environmental education in our school is based on ecosystem approach. What is an ecosystem approach? Ecosystem is a fundamental concept of ecology. Living organisms and their non-living environments interact with each other as a system, and the biosphere planet functions as a global ecosystem. Therefore, it is necessary for children to understand relationships in ecosystems, and we have to develop systems thinking in our students. Ecosystem approach and systems thinking should help us to solve global environmental problems. How do we implement the ecosystem approach? Students must understand that our biosphere functions as a single ecosystem and even small changes can lead to environmental disasters. Even the disappearance of one plant or animal species can lead to irreversible consequences. So in the classroom we learn the importance of each living organism for the nature. We pay special attention to endangered species, which are listed in the Red Data List. Kids are doing projects about these organisms, make videos, print brochures and newspapers. Fieldwork also plays an important role for ecosystem approach. Every summer, we go out for expeditions to study species of plants and animals listed in the Red Data List of Tatarstan. In class, students often write essays on behalf of any endangered species of plants or animals, this also helps them to understand the importance of each living organism in nature. Each spring we organise a festival of environmental projects among students. Groups of 4-5 students work on a solution of environmental problems, such as water, air or soil pollution, waste recycling, the loss of biodiversity, etc. Participants shoot a clip about their project, print brochures. Furthermore, some of the students participate in national and international scientific Olympiads with their projects. In addition to

  19. Regime shifts and resilience in China's coastal ecosystems.

    Science.gov (United States)

    Zhang, Ke

    2016-02-01

    Regime shift often results in large, abrupt, and persistent changes in the provision of ecosystem services and can therefore have significant impacts on human wellbeing. Understanding regime shifts has profound implications for ecosystem recovery and management. China's coastal ecosystems have experienced substantial deterioration within the past decades, at a scale and speed the world has never seen before. Yet, information about this coastal ecosystem change from a dynamics perspective is quite limited. In this review, I synthesize existing information on coastal ecosystem regime shifts in China and discuss their interactions and cascading effects. The accumulation of regime shifts in China's coastal ecosystems suggests that the desired system resilience has been profoundly eroded, increasing the potential of abrupt shifts to undesirable states at a larger scale, especially given multiple escalating pressures. Policy and management strategies need to incorporate resilience approaches in order to cope with future challenges and avoid major losses in China's coastal ecosystem services.

  20. Impact intensities of climatic changes on grassland ecosystems in ...

    African Journals Online (AJOL)

    Rainfall and temperature are the direct driving factors that affect grassland ecosystem evolution. The study constructed the assessment model of the driving factors, temperature and rainfall, that exerted influence on the primary productivities of the grassland ecosystems in headwater areas, and used the model to ...

  1. Ecosystem services in sustainable groundwater management.

    Science.gov (United States)

    Tuinstra, Jaap; van Wensem, Joke

    2014-07-01

    The ecosystem services concept seems to get foothold in environmental policy and management in Europe and, for instance, The Netherlands. With respect to groundwater management there is a challenge to incorporate this concept in such a way that it contributes to the sustainability of decisions. Groundwater is of vital importance to societies, which is reflected in the presented overview of groundwater related ecosystem services. Classifications of these services vary depending on the purpose of the listing (valuation, protection, mapping et cetera). Though the scientific basis is developing, the knowledge-availability still can be a critical factor in decision making based upon ecosystem services. The examples in this article illustrate that awareness of the value of groundwater can result in balanced decisions with respect to the use of ecosystem services. The ecosystem services concept contributes to this awareness and enhances the visibility of the groundwater functions in the decision making process. The success of the ecosystem services concept and its contribution to sustainable groundwater management will, however, largely depend on other aspects than the concept itself. Local and actual circumstances, policy ambitions and knowledge availability will play an important role. Solutions can be considered more sustainable when more of the key elements for sustainable groundwater management, as defined in this article, are fully used and the presented guidelines for long term use of ecosystem services are respected. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Brain-derived neurotrophic factor (BDNF) serum basal levels is not affected by power training in mobility-limited older adults - A randomized controlled trial.

    Science.gov (United States)

    Hvid, L G; Nielsen, M K F; Simonsen, C; Andersen, M; Caserotti, P

    2017-07-01

    Brain-derived neurotrophic factor (BDNF) is a potential important factor involved in neuroplasticity, and may be a mediator for eliciting adaptations in neuromuscular function and physical function in older individuals following physical training. As power training taxes the neural system to a very high extent, it may be particularly effective in terms of eliciting increases in systemic BDNF levels. We examined the effects of 12weeks of power training on mature BDNF (mBDNF) and total BDNF (tBDNF) in mobility-limited older adults from the Healthy Ageing Network of Competence (HANC) study. We included 47 older men and women: n=22 in the training group (TG: progressive high intensity power training, 2 sessions per week; age 82.7±5.4years, 55% women) and n=25 in the control group (CG: no interventions; age 82.2±4.5years, 76% women). Following overnight fasting, basal serum levels of mBDNF and tBDNF were assessed (human ELISA kits) at baseline and post-intervention. At baseline, mBDNF and tBDNF levels were comparable in the two groups, TG and CG. Post-intervention, no significant within-group or between-group changes were observed in mBDNF or tBDNF. Moreover, when divided into responder tertiles based upon changes in mBDNF and tBDNF (i.e. decliners, maintainers, improvers), respectively, comparable findings were observed for TG and CG. Altogether, basal systemic levels of serum mBDNF and tBDNF are not affected in mobility-limited older adults following 12-weeks of power training, and do not appear to be a major mechanistic factor mediating neuroplasticity in mobility-limited older adults. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Meta-ecosystem dynamics and functioning on finite spatial networks

    OpenAIRE

    Marleau, Justin N.; Guichard, Frédéric; Loreau, Michel

    2014-01-01

    The addition of spatial structure to ecological concepts and theories has spurred integration between sub-disciplines within ecology, including community and ecosystem ecology. However, the complexity of spatial models limits their implementation to idealized, regular landscapes. We present a model meta-ecosystem with finite and irregular spatial structure consisting of local nutrient–autotrophs–herbivores ecosystems connected through spatial flows of materials and organisms. We study the eff...

  4. Parallel Computing for Terrestrial Ecosystem Carbon Modeling

    International Nuclear Information System (INIS)

    Wang, Dali; Post, Wilfred M.; Ricciuto, Daniel M.; Berry, Michael

    2011-01-01

    Terrestrial ecosystems are a primary component of research on global environmental change. Observational and modeling research on terrestrial ecosystems at the global scale, however, has lagged behind their counterparts for oceanic and atmospheric systems, largely because the unique challenges associated with the tremendous diversity and complexity of terrestrial ecosystems. There are 8 major types of terrestrial ecosystem: tropical rain forest, savannas, deserts, temperate grassland, deciduous forest, coniferous forest, tundra, and chaparral. The carbon cycle is an important mechanism in the coupling of terrestrial ecosystems with climate through biological fluxes of CO 2 . The influence of terrestrial ecosystems on atmospheric CO 2 can be modeled via several means at different timescales. Important processes include plant dynamics, change in land use, as well as ecosystem biogeography. Over the past several decades, many terrestrial ecosystem models (see the 'Model developments' section) have been developed to understand the interactions between terrestrial carbon storage and CO 2 concentration in the atmosphere, as well as the consequences of these interactions. Early TECMs generally adapted simple box-flow exchange models, in which photosynthetic CO 2 uptake and respiratory CO 2 release are simulated in an empirical manner with a small number of vegetation and soil carbon pools. Demands on kinds and amount of information required from global TECMs have grown. Recently, along with the rapid development of parallel computing, spatially explicit TECMs with detailed process based representations of carbon dynamics become attractive, because those models can readily incorporate a variety of additional ecosystem processes (such as dispersal, establishment, growth, mortality etc.) and environmental factors (such as landscape position, pest populations, disturbances, resource manipulations, etc.), and provide information to frame policy options for climate change

  5. Elasticity in ecosystem services: exploring the variable relationship between ecosystems and human well-being

    Directory of Open Access Journals (Sweden)

    Tim M. Daw

    2016-06-01

    Full Text Available Although ecosystem services are increasingly recognized as benefits people obtain from nature, we still have a poor understanding of how they actually enhance multidimensional human well-being, and how well-being is affected by ecosystem change. We develop a concept of "ecosystem service elasticity" (ES elasticity that describes the sensitivity of human well-being to changes in ecosystems. ES Elasticity is a result of complex social and ecological dynamics and is context dependent, individually variable, and likely to demonstrate nonlinear dynamics such as thresholds and hysteresis. We present a conceptual framework that unpacks the chain of causality from ecosystem stocks through flows, goods, value, and shares to contribute to the well-being of different people. This framework builds on previous conceptualizations, but places multidimensional well-being of different people as the final element. This ultimately disaggregated approach emphasizes how different people access benefits and how benefits match their needs or aspirations. Applying this framework to case studies of individual coastal ecosystem services in East Africa illustrates a wide range of social and ecological factors that can affect ES elasticity. For example, food web and habitat dynamics affect the sensitivity of different fisheries ecosystem services to ecological change. Meanwhile high cultural significance, or lack of alternatives enhance ES elasticity, while social mechanisms that prevent access can reduce elasticity. Mapping out how chains are interlinked illustrates how different types of value and the well-being of different people are linked to each other and to common ecological stocks. We suggest that examining chains for individual ecosystem services can suggest potential interventions aimed at poverty alleviation and sustainable ecosystems while mapping out of interlinkages between chains can help to identify possible ecosystem service trade-offs and winners and

  6. What can ecology contribute to ecosystem-based management?

    Science.gov (United States)

    Thrush, Simon F; Dayton, Paul K

    2010-01-01

    Modern fishing changes the ocean environment in many ways, including disturbing the sea floor, altering the food webs, and shifting many important ecosystem functions. Natural history, oceanographic, habitat, behavior, and ecological information must be integrated to implement meaningful ecosystem-based management. We discuss the urgent need to expand the concept of essential fish habitat to include important food-web relationships. The need for a broader perspective in terms of ecosystem function and the effects of interactive stressors is emphasized to maintain the vitality and resilience of valued ecosystems. Maintenance of multiple ecosystem functions is a key factor in the adaptive capacity of ecosystems to change. We argue that an ecological understanding of resilience embraces uncertainty and encourages multiple approaches to the management of humans such that ecosystem functions are maintained.

  7. ′Ha! What is the benefit of living next to the park?′ Factors limiting in-migration next to Tarangire National Park, Tanzania

    Directory of Open Access Journals (Sweden)

    Alicia Davis

    2011-01-01

    Full Text Available Controversies and contestations of park and other protected area policies, new conservation rules and regulations (formal and informal, and new land classifications are redefining land and resource use, and thus livelihood options, for four ethnically distinct communities around Tarangire National Park, Tanzania. Research was conducted on how livelihoods have been shaped by perceptions of and in response to conservation policies and community-based conservation projects. Several factors were revealed that provide examples of perceived problems and issues, which would deter in-migration to these communities bordering a national park. Migration into these areas, located to the east, north-west, and western border of Tarangire National Park may be limited, at best, due to issues of fear and mistrust, lack of access to and alienation from land and resources, ethnicity, and litigious actions. This paper addresses these limiting factors, revealing how real world examples of conservation issues can be used to inform policy, rather than relying solely on statistical-based modelling.

  8. DNA polymerase eta is a limiting factor for A:T mutations in Ig genes and contributes to antibody affinity maturation.

    Science.gov (United States)

    Masuda, Keiji; Ouchida, Rika; Yokoi, Masayuki; Hanaoka, Fumio; Azuma, Takachika; Wang, Ji-Yang

    2008-10-01

    DNA polymerase eta (POLH) is required for the generation of A:T mutations during the somatic hypermutation of Ig genes in germinal center B cells. It remains unclear, however, whether POLH is a limiting factor for A:T mutations and how the absence of POLH might affect antibody affinity maturation. We found that the heterozygous Polh+/- mice exhibited a significant reduction in the frequency of A:T mutations in Ig genes, with each type of base substitutions at a level intermediate between the Polh+/+ and Polh(-/-) mice. These observations suggest that Polh is haplo-insufficient for the induction of A:T mutations in Ig genes. Intriguingly, there was also a reduction of C to T and G to A transitions in Polh+/- mice as compared with WT mice. Polh(-/-) mice produced decreased serum titers of high-affinity antibodies against a T-dependent antigen, which was associated with a significant reduction in the number of plasma cells secreting high-affinity antibodies. Analysis of the V region revealed that aa substitutions caused by A:T mutations were greatly reduced in Polh(-/-) mice. These results demonstrate that POLH is a limiting factor for A:T mutations and contributes to the efficient diversification of Ig genes and affinity maturation of antibodies.

  9. Payments for Ecosystem Services

    DEFF Research Database (Denmark)

    Chan, Kai M.A; Anderson, Emily K.; Chapman, Mollie

    2017-01-01

    Payments for ecosystem services (PES) programs are one prominent strategy to address economic externalities of resource extraction and commodity production, improving both social and ecological outcomes. But do PES and related incentive programs achieve that lofty goal? Along with considerable...

  10. Ecosystem Analysis Program

    International Nuclear Information System (INIS)

    Burgess, R.L.

    1978-01-01

    Progress is reported on the following research programs: analysis and modeling of ecosystems; EDFB/IBP data center; biome analysis studies; land/water interaction studies; and computer programs for development of models

  11. Revisiting software ecosystems research

    DEFF Research Database (Denmark)

    Manikas, Konstantinos

    2016-01-01

    ‘Software ecosystems’ is argued to first appear as a concept more than 10 years ago and software ecosystem research started to take off in 2010. We conduct a systematic literature study, based on the most extensive literature review in the field up to date, with two primarily aims: (a) to provide...... an updated overview of the field and (b) to document evolution in the field. In total, we analyze 231 papers from 2007 until 2014 and provide an overview of the research in software ecosystems. Our analysis reveals a field that is rapidly growing both in volume and empirical focus while becoming more mature...... from evolving. We propose means for future research and the community to address them. Finally, our analysis shapes the view of the field having evolved outside the existing definitions of software ecosystems and thus propose the update of the definition of software ecosystems....

  12. Soil to plant 137Cs transfer factors in Zea mays and Phaseolus vulgaris in a semi-arid ecosystem from a radioactive waste site

    International Nuclear Information System (INIS)

    Cervantes, M.L.; Segovia, N.; Gaso, M.I.; Palacios, J.C.

    2002-01-01

    A study of 137 Cs in soil, maize plants, (Zea mays) and beans (Phaseolus vulgaris) has been performed at the confined Storage Centre for Radioactive Waste from Mexico. Under field conditions the site was divided in four zones with different soil contamination characteristics. The plants were grown 'in situ' reproducing the local agricultural practices without fertilizers, pesticides or artificial irrigation.The 137 Cs determinations were performed using a low background gamma spectrometry system with an HPGe detector. The results indicate that one of the zones had a striking 137 Cs contamination in the soil and the uptake by the grown plants showed the highest specific activities at the root. For the edible parts of the plants the amount of 137 Cs in the maize grains was one order of magnitude lower than for the beans. The transfer factors ranges for the different parts of the maize plants was from 0.001 in the grain to 0.6 in the root. (author)

  13. Aquatic macroinvertebrates associated with Eichhornia azurea (Swartz Kunth and relationships with abiotic factors in marginal lentic ecosystems (São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    CV. Silva

    Full Text Available Marginal lakes are characterised by their having high biological diversity due to the presence of aquatic macrophytes in their coastal zones, providing habitats for refuge and food for animal community members. Among the fauna components associated with macrophytes, aquatic macroinvertebrates are important because they are an energy source for predators and fish. In six lakes and two different seasons (March and August 2009, the ecological attributes of aquatic macroinvertebrate community associated with Eichhornia azurea were compared and the controlling environmental factors were identified. Since the attributes of macroinvertebrate community are strictly associated with abiotic variables of each distinct habitat, our hypothesis was that each site associated with the same floating aquatic macrophyte (E. azurea should have a typical composition and density of organisms. We identified 50 taxa of macroinvertebrates, with greater taxa richness for aquatic insects (37 taxa divided into eight orders; the order Diptera being the most abundant in the two study periods. On the other hand, higher values of total taxa richness were recorded in August. Dissolved oxygen and pH presented the greatest number of significant positive correlations with the different taxa. The animals most frequently collected in the six lakes in March and August 2009 were Hirudinea, Oligochaeta, Hydrachnidae, Conchostraca, Ostracoda, Noteridae, Ceratopogonidae, Chironomidae, Culicidae, Caenidae, Pleidae, Aeshnidae, Libellulidae, Coenagrionidae and Nematoda. Only densities of Trichoptera, Ostracoda and Conchostraca presented the highest significant differences between lakes in both study periods and considering the composition of macroinvertebrates no significant differences were registered for macroinvertebrate composition.

  14. Aquatic macroinvertebrates associated with Eichhornia azurea (Swartz) Kunth and relationships with abiotic factors in marginal lentic ecosystems (São Paulo, Brazil).

    Science.gov (United States)

    Silva, C V; Henry, R

    2013-02-01

    Marginal lakes are characterised by their having high biological diversity due to the presence of aquatic macrophytes in their coastal zones, providing habitats for refuge and food for animal community members. Among the fauna components associated with macrophytes, aquatic macroinvertebrates are important because they are an energy source for predators and fish. In six lakes and two different seasons (March and August 2009), the ecological attributes of aquatic macroinvertebrate community associated with Eichhornia azurea were compared and the controlling environmental factors were identified. Since the attributes of macroinvertebrate community are strictly associated with abiotic variables of each distinct habitat, our hypothesis was that each site associated with the same floating aquatic macrophyte (E. azurea) should have a typical composition and density of organisms. We identified 50 taxa of macroinvertebrates, with greater taxa richness for aquatic insects (37 taxa) divided into eight orders; the order Diptera being the most abundant in the two study periods. On the other hand, higher values of total taxa richness were recorded in August. Dissolved oxygen and pH presented the greatest number of significant positive correlations with the different taxa. The animals most frequently collected in the six lakes in March and August 2009 were Hirudinea, Oligochaeta, Hydrachnidae, Conchostraca, Ostracoda, Noteridae, Ceratopogonidae, Chironomidae, Culicidae, Caenidae, Pleidae, Aeshnidae, Libellulidae, Coenagrionidae and Nematoda. Only densities of Trichoptera, Ostracoda and Conchostraca presented the highest significant differences between lakes in both study periods and considering the composition of macroinvertebrates no significant differences were registered for macroinvertebrate composition.

  15. [Comparative analysis of natural uranium mobility and concentration process in ecosystems of the Pechora river basin].

    Science.gov (United States)

    Rachkova, N G; Shuktomova, I I

    2013-01-01

    Natural uranium mobility and its concentration process in water ecosystems of the Pechora river basin situated in the areas with the uranium increased concentration in rocks and in the zone around radioactive waste repository were compared. The study investigated the influence of the environmental factors on the uranium distribution in water reservoirs. In the studied ecosystems, Fe-bearing compounds are major sorbents of uranium during the migration and concentration process. Nitrate-ions increase the uranium mobility in the ecosystems. The influence of sulfate, phosphate and carbonate complexation on the uranium distribution between water and bottom sediments wasn't pronounced in the ecosystems with high natural radioactivity, but significant for the radioactively contaminated water reservoirs. Uranium geochemical mobility is higher in contaminated water ecosystems. The uranium content in the water from this area substantially exceeds the background value for the region and toxicity limits for hydrophytes. Comparison of the current and earlier received data shows that the uranium concentration in the water has decreased, its specific activity in sediments has enhanced. The level of the uranium concentration in dry hygrophyte biomass has not changed.

  16. Tenax TA extraction to understand the rate-limiting factors in methyl-β-cyclodextrin-enhanced bioremediation of PAH-contaminated soil.

    Science.gov (United States)

    Sun, Mingming; Luo, Yongming; Teng, Ying; Christie, Peter; Jia, Zhongjun; Li, Zhengao

    2013-06-01

    The effectiveness of many bioremediation systems for PAH-contaminated soil may be constrained by low contaminant bioaccessibility due to limited aqueous solubility or large sorption capacity. Information on the extent to which PAHs can be readily biodegraded is of vital importance in the decision whether or not to remediate a contaminated soil. In the present study the rate-limiting factors in methyl-β-cyclodextrin (MCD)-enhanced bioremediation of PAH-contaminated soil were evaluated. MCD amendment at 10 % (w/w) combined with inoculation with the PAH-degrading bacterium Paracoccus sp. strain HPD-2 produced maximum removal of total PAHs of up to 35 %. The desorption of PAHs from contaminated soil was determined before and after 32 weeks of bioremediation. 10 % (w/w) MCD amendment (M2) increased the Tenax extraction of total PAHs from 12 to 30 % and promoted degradation by up to 26 % compared to 6 % in the control. However, the percentage of Tenax extraction for total PAHs was much larger than that of degradation. Thus, in the control and M2 treatment it is likely that during the initial phase the bioaccessibility of PAHs is high and biodegradation rates may be limited by microbial processes. On the other hand, when the soil was inoculated with the PAH-degrading bacterium (CKB and MB2), the slowly and very slowly desorbing fractions (F sl and F vl ) became larger and the rate constants of slow and very slow desorption (k sl and k vl ) became extremely small after bioremediation, suggesting that desorption is likely rate limiting during the second, slow phase of biotransformation. These results have practical implications for site risk assessment and cleanup strategies.

  17. REVIEW: Mangrove ecosystem in Java: 1. recent status

    Directory of Open Access Journals (Sweden)

    PURIN CANDRA PURNAMA

    2003-07-01

    Full Text Available Mangrove ecosystem is a specific ecosystem that only take about 2% of total land in the earth. Indonesian mangrove ecosystem is the widest in the world and as a center of distributioan and ecosystem biodiversity, however it undergoes rapid and dramatic destruction. In just 11 years, between 1982-1993, more than 50% of Indonesian mangrove disappeared. The most factor threatening the mangrove ecosystem is human activities, including convertion to aquaculture, deforestation, and environmental pollution. Other factors such as reclamation, sedimentation, and natural dis