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Latest investigations on atmospheric carbon tetrachloride (CTC) are focused on its ozone depleting potential, adverse effects on the human health, and radiative efficiency and Global Warming Potential as a greenhouse gas. CTC mixing ratios have been thoroughly studied since its restriction under the Montreal Protocol, mostly in remote areas with the aim of reporting long-term trends after its banning. The observed decrease of the CTC background mixing ratio, however, was not as strong as expected. In order to explain this behavior CTC lifetime should be adjusted by estimating the relative significance of its sinks and by identifying ongoing potential sources.
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In most countries, the loss of biodiversity caused by the fires is worrying. In this sense, the fires detection towers are crucial for rapid identification of fire outbreaks and can also be used in environmental inspection, biodiversity monitoring, telecommunications mechanisms, telemetry and others. Currently the methodologies for allocating fire detection towers over large areas are numerous, complex and non-standardized by government supervisory agencies. Therefore, this study proposes and evaluates different methodologies to best location of points to install fire detection towers considering the topography, risk areas, conservation units and heat spots. Were used Geographic Information Systems (GIS) techniques and unaligned stratified systematic sampling for implementing and evaluating 9 methods for allocating fire detection towers. Among the methods evaluated, the C3 method was chosen, represented by 140 fire detection towers, with coverage of: a) 67% of the study area, b) 73.97% of the areas with high risk, c) 70.41% of the areas with very high risk, d) 70.42% of the conservation units and e) 84.95% of the heat spots in 2014. The proposed methodology can be adapted to areas of other countries.
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A simulation testing framework was developed to evaluate the efficacy of detecting population trends of two sampling methods used to monitor inshore fish populations: angling and baited remote underwater stereo-video systems (stereo-BRUVs). The study is based on data collected as part of a long-term monitoring program in the Tsitsikamma National Park marine protected area, South Africa. As a test scenario, declining population trajectories of the most abundant species, Chrysoblephus laticeps, were simulated by introducing consecutive years of reduced recruitment over periods of 10 and 20 years applying an age-structured operating model. The operating model was designed to generate method-specific relative abundance indices and length–frequency data, using parameters derived from existing data collected in the long-term monitoring program. These were then fitted with an age-structured estimation model. Estimated spawner-biomass depletion was compared to the ‘true’ simulated population to quantify method-specific accuracy and bias using root-mean-squared error. Due to higher data variability and inherent size selectivity of angling, stereo-BRUVs provided more accurate spawner-biomass trends when describing a distinct population decline over 10 and 20 years. Additionally, spawner-biomass was found to be a more accurate population estimate than relative abundance indices due to the inclusion of population size structure information. The study demonstrates the potential of using simulation testing to evaluate sampling methods, given that the process generates the ‘true’ population with a known abundance and size structure.
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The Belgian territory has yielded a rich archaeological record related to the Ancient Palaeolithic, with 442 locations from this period. Of these, some were recovered in stratigraphic position and provide archaeological, chronostratigraphic and palaeoenvironmental data on the Lower to Middle Palaeolithic transition. In this paper, we present the oldest archaeological remains from the Belgian territory, from the first documented human settlements to the beginning of the Middle Palaeolithic (MIS 8). We then discuss the chronostratigraphic distribution of the sites, land-use strategies, and the Lower to Middle Palaeolithic transition in relation to the issue of the emergence of sophisticated prepared-core technologies, such as Levallois, in the North-Western European context.
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Forest ecosystems are major providers of high quality water and contribute to maintain a better distribution of base flows during the year. However, these environmental services have been adversely affected by human pressure due to the decline and deterioration of forested areas and the inadequate management of water resources. To better understand the relations between human population, forest area and water quality and yield, at a regional level, we studied six catchments located in the upper Grijalva river basin in the border between Guatemala and Mexico. Measurements of twelve water quality parameters and water yield from nine sampling periods during 2011–2013 were analyzed through PLS (partial least squares) regression, ANOVA and linear mixed models to assess the season effect on water quality and the forest cover effect on water yield. An ordination by PCA (principal components analysis) and Pearson's pair-wise correlations were used to identify association between hydrological and social catchment features (forest cover, protection of riparian buffer strips, population density and urban areas). Our results suggest that overall water quality is higher during the dry season (higher values of dissolved oxygen and lower levels of total dissolved solids, total suspended solids, total phosphorus, chemical oxygen demand and temperature were observed). Water yield is positively related to forest cover and riparian buffer strips, becoming essential in maintaining water security for local populations. Major threats to water flux and their quality are related to human pressures and untreated wastewater discharges, which reduce water quality of the receiving rivers.
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Seagrasses worldwide are highly vulnerable to, and at increasing risk from reduced light availability, and robust light thresholds are required for evaluating future impacts of changing light conditions. We tested the morphological response (shoot density and growth) of four Indo-West Pacific seagrass species (Cymodocea serrulata, Halodule uninervis, Halophila ovalis and Zostera muelleri) to six daily light levels ranging from 0 to 23molm−2d−1 (0–70% surface irradiance) in cool (∼23°C) and warm temperatures (∼28°C) over 14 weeks. The impact of light limitation on shoot densities and growth rates was higher at warm than at cool temperatures, and for Z. muelleri and H. ovalis than for C. serrulata and H. uninervis, in terms of both the time taken for the low light treatment to take effect and the predicted time to shoot loss (e.g. 17–143 days at 0molm−2d−1). Using fitted curves we estimated temperature-dependent thresholds (with estimates of uncertainty) for 50% and 80% protection of growth and shoot density, defined here as “potential light thresholds” in recognition that they were derived under experimental conditions. Potential light thresholds that maintained 50% and 80% of seagrass shoot density fell within the ranges 1.1–5.7molm−2d−1 and 3.8–10.4molm−2d−1, respectively, depending on temperature and species. Light thresholds calculated in separate in situ studies for two of the same species produced comparable results. We propose that the upper (rounded) values of 6molm−2d−1 and 10molm−2d−1 can be used as potential light thresholds for protecting 50% and 80% of shoot density for these four species over 14 weeks. As management guidelines should always be more conservative than thresholds for biological declines, we used error estimates to provide a quantitative method for converting potential light thresholds into guidelines that satisfy this criterion. The present study demonstrates a new approach to deriving potential light thresholds for acute impacts, describes how they can be applied in management guidelines and quantifies the timescales of seagrass decline in response to light limitation. This method can be used to further quantify cumulative impacts on potential light thresholds.
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The Double-crested Cormorant (Phalacrocorax auritus) is culled in many states because of the real and presumed damages it inflicts on farmed and recreational fisheries and other ecosystem services. Resident cormorant colonies breeding in the southeastern United States are protected in some areas, so it is important to distinguish these from co-occurring but unprotected migratory cormorants. Migratory P. auritus are likely to contain helminthic parasite communities that differ from those of non-migratory, resident birds, because they will encounter a wider variety of habitats and intermediate host communities during migrations. Here, we document five distinct assemblages of helminth parasites collected from 218 P. auritus culled from 11 sites in Alabama, Minnesota, Mississippi, and Vermont. The assemblages of P. auritus parasites are distinct among many sampling locations and can be used to correctly predict where a host cormorant has been feeding. We provide evidence for mixing of cormorants at a regional scale using discriminant analysis, which suggests there is a single population of migratory cormorants. Furthermore, our models strongly differentiate between migratory and resident P. auritus in the southeastern United States. In conjunction with species-by species latitudinal and longitudinal trends, our models could serve as effective tools for managers interested in both the population control of migratory cormorants and the conservation of non-migratory, resident birds. Finally, parasite counts per host are notoriously variable with many zeros and a few large numbers, leading many researchers to use simple prevalence in their analyses. We show that an intermediate level of data resolution, using species occurrence ranks within individual hosts, behaves well statistically and provides the greatest discrimination among distinct host groupings.
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The structural framework and tectonic evolution of the sedimentary basins along the eastern margin of the South American continent are closely associated with the tectonic framework and crustal heterogeneities inherited from the Precambrian basement. However, the role of NW-SE and NNW-SSE structures observed at the outcropping basement in Southeastern Brazil and its impact over the development of those basins have not been closely investigated. In the continental region adjacent to the Campos Basin, we described a geological feature with NNW-SSE orientation, named in this paper as the Alegre Fracture Zone (AFZ), which is observed in the onshore basement and can be projected to the offshore basin. The main goal of this work was to study this structural lineament and its influence on the tectonic evolution of the central portion of the Campos Basin and adjacent mainland. The onshore area was investigated through remote sensing data joint with field observations, and the offshore area was studied through the interpretation of 2-D seismic data calibrated by geophysical well logs. We concluded that the AFZ occurs in both onshore and offshore as a brittle deformation zone formed by multiple sets of fractures that originated in the Cambrian and were reactivated mainly as normal faults during the rift phase and in the Cenozoic. In the Campos Basin, the AFZ delimitates the western side of the Corvina-Parati Low, composing a complex fault system with the NE-SW faults and the NW-SE transfer faults.
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We offer a dynamical model of phonological planning that provides a formal instantiation of how the speech production and perception systems interact during online processing. The model is developed on the basis of evidence from an experimental task that requires concurrent use of both systems, the so-called response–distractor task in which speakers hear distractor syllables while they are preparing to produce required responses. The model formalizes how ongoing response planning is affected by perception and accounts for a range of results reported across previous studies. It does so by explicitly addressing the setting of parameter values in representations. The key unit of the model is that of the dynamic field, a distribution of activation over the range of values associated with each representational parameter. The setting of parameter values takes place by the attainment of a stable distribution of activation over the entire field, stable in the sense that it persists even after the response cue in the above experiments has been removed. This and other properties of representations that have been taken as axiomatic in previous work are derived by the dynamics of the proposed model.
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Abiotic stress has been shown to significantly limit the growth and productivity of crops. NAC transcription factors play essential roles in response to various abiotic stresses. However, only little information regarding stress-related NAC genes is available in maize. Here, we cloned a maize NAC transcription factor ZmNAC55 and identified its function in drought stress. Transient expression and transactivation assay demonstrated that ZmNAC55 was localized in the nucleus and had transactivation activity. Expression analysis of ZmNAC55 in maize showed that this gene was induced by drought, high salinity and cold stresses and by abscisic acid (ABA). Promoter analysis demonstrated that multiple stress-related cis-acting elements exist in promoter region of ZmNAC55. Overexpression of ZmNAC55 in Arabidopsis led to hypersensitivity to ABA at the germination stage, but enhanced drought resistence compared to wild-type seedlings. Transcriptome analysis identified a number of differentially expressed genes between 35S::ZmNAC55 transgenic and wild-type plants, and many of which are involved in stress response, including twelve qRT–PCR confirmed well-known drought-responsive genes. These results highlight the important role of ZmNAC55 in positive regulates of drought resistence, and may have potential applications in transgenic breeding of drought-tolerant crops.
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