56 research outputs found
Por uma sociologia crĂtica da ciĂȘncia
Neste artigo crĂtico e construtivo, defendemos que a Sociologia da CiĂȘncia, como estĂĄ estabelecida, Ă© distorcida por uma suposta filosofia idealista que estimula uma atitude acrĂtica em relação ao que se supĂ”e serem fatos. Propomos uma sociologia crĂtica da ciĂȘncia que faz a distinção entre ciĂȘncia, ciĂȘncia aplicada e tecnologia; enfoca a falibilidade da ciĂȘncia e da sociologia da ciĂȘncia que desconstrĂłi toda pretensĂŁo de autoridade. Construtivamente, esboçamos os elementos de uma sociologia da ciĂȘncia que envolve as formas elementares da vida cientĂfica, bem como a ciĂȘncia "normal" contemporĂąnea, burocratizada e militarizada
Potential drivers of changing ecological conditions in English and Welsh rivers since 1990
River invertebrate communities across Europe have been changing in response to variations in water quality over recent decades, but the underlying drivers are difficult to identify because of the complex stressors and environmental heterogeneity involved. Here, using data from ~4000 locations across England and Wales, collected over 29âŻyears, we use three approaches to help resolve the drivers of spatiotemporal variation in the face of this complexity: i) mapping changes in invertebrate richness and community composition; ii) structural equation modelling (SEM) to distinguish land cover, water quality and climatic influences; and iii) geographically weighted regression (GWR) to identify how the apparent relationships between invertebrate communities and abiotic variables change across the area. Mapping confirmed widespread increases in richness and the proportion of pollution-sensitive taxa across much of England and Wales. It also revealed regions where pollution-sensitive taxa or overall richness declined, the former primarily in the uplands. SEMs confirmed strong increases in average biochemical oxygen demand and nutrient concentrations related to urban and agricultural land cover, but only a minority of land cover's effect upon invertebrate communities was explained by average water chemistry, highlighting potential factors such as episodic extremes or emerging contaminants. GWR identified strong geographical variation in estimated relationships between macroinvertebrate communities and environmental variables, with evidence that the estimated negative impacts of nutrients and water temperature were increasing through time. Overall the results are consistent with widespread biological recovery of Britain's rivers from past gross organic pollution, whilst highlighting declines in some of the most diverse and least impacted streams. Modelling points to a complex and changing set of drivers, highlighting the multifaceted impacts of catchment land cover and the evolving role of different stressors, with the relationship to gross organic pollution weakening, whilst estimated nutrient and warming effects strengthened
Digital Fabrication and Its Meanings for Photography and Film
Bazin, Cavell and other prominent theorists have asserted that movies are essentially photographic, with more recent scholars such as Carroll and Gaut protesting. Today CGI stands as a further counter, in addition to past objections such as editing, animation and blue screen. Also central in debates is whether photography is transparent, that is, whether it allows us to see things in other times and places. I maintain photography is transparent, notwithstanding objections citing digital manipulation. However, taking a cue from Cavellâalbeit one poorly outlined in his workâI argue this is not so much because of what photography physically is, but because of what âphotographyâ has come to mean. I similarly argue digital technologies have not significantly altered what cinematic media âareâ because they have not fundamentally modified what they mean; and that cinema retains a photographic legacy, even when it abandons photographic technologies to digitally manufacture virtual worlds
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International films and international markets: the globalisation of Hollywood entertainment, c.1921-1951
The international appeal of Hollywood films through the twentieth century has been a subject of interest to economic and film historians alike. This paper employs some of the methods of the economic historian to evaluate key arguments within the film history literature explaining the global success of American films. Through careful analysis of both existing and newly constructed data sets, the paper examines the extent to which Hollywood's foreign earnings were affected by: film production costs; the extent of global distribution networks; and also the international orientation of the films themselves. The paper finds that these factors influenced foreign earnings in quite distinct ways, and that their relative importance changed over time. The evidence presented here suggests a degree of interaction between the production and distribution arms of the major US film companies in their pursuit of foreign markets that would benefit from further archival-based investigation
Small Water Bodies in Great Britain and Ireland: Ecosystem function, human-generated degradation, and options for restorative action
© 2018 Small, 1st and 2nd-order, headwater streams and ponds play essential roles in providing natural flood control, trapping sediments and contaminants, retaining nutrients, and maintaining biological diversity, which extend into downstream reaches, lakes and estuaries. However, the large geographic extent and high connectivity of these small water bodies with the surrounding terrestrial ecosystem makes them particularly vulnerable to growing land-use pressures and environmental change. The greatest pressure on the physical processes in these waters has been their extension and modification for agricultural and forestry drainage, resulting in highly modified discharge and temperature regimes that have implications for flood and drought control further downstream. The extensive length of the small stream network exposes rivers to a wide range of inputs, including nutrients, pesticides, heavy metals, sediment and emerging contaminants. Small water bodies have also been affected by invasions of non-native species, which along with the physical and chemical pressures, have affected most groups of organisms with consequent implications for the wider biodiversity within the catchment. Reducing the impacts and restoring the natural ecosystem function of these water bodies requires a three-tiered approach based on: restoration of channel hydromorphological dynamics; restoration and management of the riparian zone; and management of activities in the wider catchment that have both point-source and diffuse impacts. Such activities are expensive and so emphasis must be placed on integrated programmes that provide multiple benefits. Practical options need to be promoted through legislative regulation, financial incentives, markets for resource services and voluntary codes and actions
From existing in situ, high-resolution measurement technologies to lab-on-a-chip – the future of water quality monitoring?
Abstract. This paper introduces new insights into the hydrochemical functioning of lowland river-systems using field-based spectrophotometric and electrode technologies. The streamwater concentrations of nitrogen species and phosphorus fractions were measured at hourly intervals on a continuous basis at two contrasting sites on tributaries of the River Thames, one draining a rural catchment, the River Enborne, and one draining a more urban system, The Cut. The measurements complement those from an existing network of multi-parameter water quality sondes maintained across the Thames catchment and weekly monitoring based on grab samples. The results of the sub-daily monitoring show that streamwater phosphorus concentrations display highly complex, seemingly chaotic, dynamics under storm conditions dependent on the antecedent catchment wetness, and that diurnal phosphorus and nitrogen cycles occur under low flow conditions. The diurnal patterns highlight the dominance of sewage inputs in controlling the streamwater phosphorus and nitrogen concentrations at low flows, even at a distance of 7 km from the nearest sewage works in the rural, River Enborne, and that the time of sample collection is important when judging water quality against ecological thresholds or standards. An exhaustion of the supply of phosphorus from diffuse and septic tank sources during storm events was evident and load estimation was not improved by sub-daily monitoring beyond that achieved by daily sampling because of the eventual reduction in the phosphorus mass entering the stream during events. The dominance of respiration over photosynthesis in The Cut indicated a prevalence of heterotrophic algae, and the seasonal patterns in respiration and photosynthesis corresponded with those of temperature and light in this nutrient over-enriched stream. These results highlight the utility of sub-daily water quality measurements but the deployment of modified wet-chemistry technologies into the field was limited by mains electricity availability. A new approach is therefore needed to allow measurement of a wide range of analytes at a broader range of locations for the development of water quality web-sensor networks. The development and field deployment of a miniaturised "lab-on-a-chip" ion chromatograph is proposed and justified.
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ENM2020 : A FREE ONLINE COURSE AND SET OF RESOURCES ON MODELING SPECIES NICHES AND DISTRIBUTIONS
The field of distributional ecology has seen considerable recent attention, particularly surrounding the theory, protocols, and tools for Ecological Niche Modeling (ENM) or Species Distribution Modeling (SDM). Such analyses have grown steadily over the past two decades-including a maturation of relevant theory and key concepts-but methodological consensus has yet to be reached. In response, and following an online course taught in Spanish in 2018, we designed a comprehensive English-language course covering much of the underlying theory and methods currently applied in this broad field. Here, we summarize that course, ENM2020, and provide links by which resources produced for it can be accessed into the future. ENM2020 lasted 43 weeks, with presentations from 52 instructors, who engaged with >2500 participants globally through >14,000 hours of viewing and >90,000 views of instructional video and question-and-answer sessions. Each major topic was introduced by an "Overview" talk, followed by more detailed lectures on subtopics. The hierarchical and modular format of the course permits updates, corrections, or alternative viewpoints, and generally facilitates revision and reuse, including the use of only the Overview lectures for introductory courses. All course materials are free and openly accessible (CC-BY license) to ensure these resources remain available to all interested in distributional ecology.Peer reviewe
Agent-Based Simulation as an Implementation of Methodological Individualism
This paper investigates the relationship between methodological individualism (MI) and Agent-Based Simulation (ABS). We discuss and analyze a thesis defended by philosophers Caterina Marchionni and Petri Ylikoski (2013). The thesis maintains that, since MI is often considered to be a reductionist approach, it is confusing and meaningless to assume that ABS, which is a non-reductionist and emergentist explanatory model, is committed to MI. We reject this thesis arguing that, from a philosophical standpoint, addressing the problem of the consistency between MI and ABS from a strictly utilitarian perspective is unsatisfactory. We analyze this problem in more substantial terms, i.e. focusing on its more theoretical and conceptual aspects. Moreover, we maintain that ABS explanations must be regarded as individualist explanations and provide a set of logical and historical arguments against the widespread interpretation of MI in terms of reductionism
Dissolved inorganic carbon export from rivers of Great Britain: Spatial distribution and potential catchment-scale controls
Dissolved inorganic carbon (DIC) fluxes from the land to ocean have been quantified for many rivers globally. However, CO2 fluxes to the atmosphere from inland waters are quantitatively significant components of the global carbon cycle that are currently poorly constrained. Understanding, the relative contributions of natural and human-impacted processes on the DIC cycle within catchments may provide a basis for developing improved management strategies to mitigate free CO2 concentrations in rivers and subsequent evasion to the atmosphere. Here, a large, internally consistent dataset collected from 41 catchments across Great Britain (GB), accounting for âŒ36% of land area (âŒ83,997 km2) and representative of national land cover, was used to investigate catchment controls on riverine dissolved inorganic carbon (DIC), bicarbonate (HCO3â) and free CO2 concentrations, fluxes to the coastal sea and annual yields per unit area of catchment. Estimated DIC flux to sea for the survey catchments was 647 kt DIC yrâ1 which represented 69% of the total dissolved carbon flux from these catchments. Generally, those catchments with large proportions of carbonate and sedimentary sandstone were found to deliver greater DIC and HCO3â to the ocean. The calculated mean free CO2 yield for survey catchments (i.e. potential CO2 emission to the atmosphere) was 0.56 t C kmâ2 yrâ1. Regression models demonstrated that whilst river DIC (R2 = 0.77) and HCO3â (R2 = 0.77) concentrations are largely explained by the geology of the landmass, along with a negative correlation to annual precipitation, free CO2 concentrations were strongly linked to catchment macronutrient status. Overall, DIC dominates dissolved C inputs to coastal waters, meaning that estuarine carbon dynamics are sensitive to underlying geology and therefore are likely to be reasonably constant. In contrast, potential losses of carbon to the atmosphere via dissolved CO2, which likely constitute a significant fraction of net terrestrial ecosystem production and hence the national carbon budget, may be amenable to greater direct management via altering patterns of land use
Raman spectroscopy as a tool to determine the thermal maturity of organic matter : application to sedimentary, metamorphic and structural geology
Raman spectrometry is a rapid, non-destructive alternative to conventional tools employed to assess the thermal alteration of organic matter (OM). Raman may be used to determine vitrinite reflectance equivalent OM maturity values for petroleum exploration, to provide temperature data for metamorphic studies, and to determine the maximum temperatures reached in fault zones. To achieve the wider utilisation of Raman, the spectrum processing method, and the positions and nomenclature of Raman bands and parameters, all need to be standardized. We assess the most widely used Raman parameters as well as the best analytical practices that have been proposed. Raman band separation and G-band full-width at half-maximum are the best parameters to estimate the maturity for rocks following diagenesisâmetagenesis. For metamorphic studies, the ratios of band areas after performing deconvolution are generally used. Further work is needed on the second-order region, as well as assessing the potential of using integrated areas on the whole spectrum, to increase the calibrated temperature range of Raman parameters. Applying Raman spectroscopy on faults has potential to be able to infer both temperature and deformation processes. We propose a unified terminology for OM Raman bands and parameters that should be adopted in the future. The popular method of fitting several functions to a spectrum is generally unnecessary, as Raman parameters determined from an un-deconvoluted spectrum can track the maturity of OM. To progress the Raman application as a geothermometer a standardized approach must be developed and tested by means of an interlaboratory calibration exercise using reference materials
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