16,592 research outputs found
Groundwater quality on a waste disposal area due to sand mining activities in São Paulo state, Brazil
No full textThis investigation reports the results of a study realized in an area related to the development of sand mining activities, which belongs to Sibelco Mineração Ltd. The site is located around Analândia municipality, nearly in the center of São Paulo State, Brazil. Hydrochemical analyses of groundwater were realized under different periods of time, with the aim of evaluating the possibility of release of several constituents to the liquid phase, which may be a source of pollution of the surface hydrological resources and of the deeper Guarani aquifer. This is because the site is located at the recharge area of Guarani aquifer and some tributaries from Corumbataí river may also be suffering contamination, implying on the impoverishment of the water quality that are very important resources in the region, as they are extensively used for drinking purposes, among others.© 2011 WIT Press.Departamento de Petrologia e Metalogenia Instituto de Geociências e Ciências Exatas-UNESP, Rio ClaroDepartamento de Geologia Aplicada, Instituto de Geociências e Ciências Exatas-UNESP, Rio ClaroDepartamento de Petrologia e Metalogenia Instituto de Geociências e Ciências Exatas-UNESP, Rio ClaroDepartamento de Geologia Aplicada, Instituto de Geociências e Ciências Exatas-UNESP, Rio Clar
Effects of the Brazilian biodiesel certification in the relationship between biodiesel industry and small-scale farmer
No full textEcosystems and Sustainable Development X
Edited By
J.L. Miralles i Garcia, Universitat Politecnica de Valencia, Spain and C.A. Brebbia, Wessex Institute of Technology, UK[EN] The production of biodiesel in Brazil is encouraged by the government through
the Fuel Stamp, a certification system linked to the National Plan for Production
and Use of Biodiesel – PNPB – aimed at promoting economic and sustainable
development. It focuses on social inclusion, also intending to reduce dependence
on fossil fuels and emission of pollutants and diversify the energetic matrix
through the use of different oil sources as raw material. Certification – and with it
a number of tax benefits – are granted to industrial processors that are supplied
with raw materials coming from small-scale farms. Thus, it facilitates the access
of the family farms in this value chain. The objective of this work is to analyze the
effects of this system of certification in the transactions between its main agents,
farmers and processing industries. For this purpose, the work makes a revision of
the studies that national public agencies have elaborated on regional cases and also
scientific publications. Results show that this measure allowed the insertion of
family farmers in the production chain and enabled the sustainable rural
development. However, it presents gaps as the occurrence of failures in the
fulfilment of contracts between family farmers and the industry. Moreover, in spite
of being crop diversification, one of the objectives of the certification system, the
preference of the industry for soy as raw material – because of technological
reasons – is displacing traditional regional crops (for example palm and castor oil).Marcossi, G.; Ortiz Miranda, D.; Moreno Pérez, OM. (2015). Effects of the Brazilian biodiesel certification in the relationship between biodiesel industry and small-scale farmer. WIT Transactions on Ecology and the Environment. 192:285-295. doi:10.2495/ECO150261S28529519
Amphetamine as a social drug: effects of d-amphetamine on social processing and behavior
No full textRationale: drug users often report using drugs to enhance social situations, and empirical studies support the idea that drugs increase both social behavior and the value of social interactions. One way drugs may affect social behavior is by altering social processing, for example by decreasing perceptions of negative emotion in others. Objectives: we examined effects of d-amphetamine on processing of emotional facial expressions, and on the social behavior of talking. We predicted amphetamine would enhance attention, identification and responsivity to positive expressions, and that this in turn would predict increased talkativeness. Methods: over three sessions, 36 healthy normal adults received placebo, 10mg, and 20mg d-amphetamine under counterbalanced double-blind conditions. At each session we measured processing of happy, fearful, sad and angry expressions using an attentional visual probe task, a dynamic emotion identification task, and measures of facial muscle activity. We also measured talking. Results: amphetamine decreased the threshold for identifying all emotions, increased negative facial responses to sad expressions, and increased talkativeness. Contrary to our hypotheses, amphetamine did not alter attention to, identification of or facial responses to positive emotions specifically. Interestingly, the drug decreased the threshold to identify all emotions, and this effect was uniquely related to increased talkativeness, even after controlling for overall sensitivity to amphetamine. Conclusions: the results suggest that amphetamine may encourage sociability by increasing sensitivity to subtle emotional expressions. These findings suggest novel social mechanisms that may contribute to the rewarding effects of amphetamine
VVV-WIT-13: An eruptive young star with cool molecular features
No full textContext.
Outburst phenomena are observed at different stages of stellar evolution, due to the enhancement of the mass accretion rate on protostars or even stellar merger events. In the case of a young stellar object (YSO), the episodic mass accretion event plays an important role in the pre-main-sequence stellar mass assembly. Here we investigate an infrared eruptive source (RA = 16:53:44.38; Dec = − 43:28:19.47), identified from the decade-long VISTA Variables in the Vía Láctea survey (VVV). We named this target after a group of variable sources discovered by VVV, as VVV-WIT-13, where WIT stands for ‘What is this?’, due to its unique photometric variation behaviour and the mysterious origin of the outburst. This target exhibited an outburst with a 5.7 mag amplitude in the
K
s
-band, remained on its brightness plateau for 3.5 years, and then rapidly faded to its pre-eruptive brightness afterwards.
Aims.
Our aim is to reveal the variable nature and outburst origin of VVV-WIT-13 by presenting our follow-up photometric and spectroscopic observations along with theoretical models.
Methods.
We gathered photometric time series in both near- and mid-infrared wavelengths. We obtained near-infrared spectra during the outburst and decaying stages on XSHOOTER/VLT and FIRE/Magellan, and then fitted the detected molecular absorption features using models from ExoMol. We applied 2D numerical simulations to re-create the observables of the eruptive phenomenon.
Results.
We observe deep AlO absorption bands in the infrared spectra of VVV-WIT-13, during the outburst stage, along with other more common absorption bands (e.g. CO). Our best-fit model suggests a 600 K temperature of the AlO absorption band. In the decaying stage, the AlO bands disappeared, whilst broad blue-shifted H
2
lines arose, a common indicator of stellar wind and outflow. The observational evidence suggests that the CO and TiO features originate from an outflow or a wind environment.
Conclusions.
We find that VVV-WIT-13 is an eruptive young star with instability occurring in the accretion disk. One favoured theoretical explanation of this event is a disrupted gas clump at a distance of 3 au from the source. If confirmed, this would be the first such event observed in real time.</p
Sensitivity of a 3-D surface mapping system to environmental perturbations
No full textA newly developed three-axes coordinate measurement machine, coupled with a confocal laser sensor, has been housed in a temperature-controlled laboratory.Initial results of three-dimensional (3-D) measurements taken off a NAMAS (TVational Accreditation of Measurement and Sampling) certified sphere were found to vary significantly with large errors.Evaluation of the possible sources of errors included drift in ambient temperature, positioning inaccuracies, and mechanical set-up errors such as orthogonality and straightness of axes.This paper investigates the sensitivity of the measurement system towards environmental perturbations, looking particularly at the influence of temperature drift.The laboratory's temperature was logged over a period of time and the data subsequently charted
VVV-WIT-07: Another Boyajian’s star or a Mamajek’s object?
No full textWe report the discovery of VVV-WIT-07, a unique and intriguing variable source presenting a sequence of recurrent dips with a likely deep eclipse in 2012 July. The object was found serendipitously in the near-IR data obtained by the VISTA Variables in the Vía Láctea (VVV) ESO public survey. Our analysis is based on VVV variability, multicolour, and proper motion (PM) data. Complementary data from the VVV eXtended survey as well as archive data and spectroscopic follow-up observations aided in the analysis and interpretation of VVV-WIT-07. A search for periodicity in the VVV Ks-band light curve of VVV-WIT-07 results in two tentative periods at P ∼ 322 d and P ∼ 170 d. Colours and PM are consistent either with a reddened main-sequence (MS) star or a pre-MS star in the foreground disc. The near-IR spectra of VVV-WIT-07 appear featureless, having no prominent lines in emission or absorption. Features found in the light curve of VVV-WIT-07 are similar to those seen in J1407 (Mamajek’s object), a pre-MS K5 dwarf with a ring system eclipsing the star or, alternatively, to KIC 8462852 (Boyajian’s star), an F3 IV/V star showing irregular and aperiodic dips in its light curve. Alternative scenarios, none of which is fully consistent with the available data, are also briefly discussed, including a young stellar object, a T Tauri star surrounded by clumpy dust structure, an MS star eclipsed by a nearby extended object, a self-eclipsing R CrB variable star, and even a long-period, high-inclination X-ray binary. © 2018 The Author(s).Universidad Autónoma de Chil
Operations on Railyard Sites, the Dutch Case: In between Landscape Design and Engineering
No full textThe technical landscape of railyard sites brings together a multidisciplinary set of expertise and needs. It entails the union of engineering and landscape design concerns, to redefine these spaces in the way they are maintained and potentially transformed. The paper gives an overview of this interplay, focusing on the Dutch panorama to describe experimental procedures to manage and leverage railyards' green spaces in their transformation. It is presented a specific case study, the design for Amsterdam PHS, where technological advancement allowed to redefine the railyard section, providing a new urban park for the city. Ultimately is explored the potentialities and impact of translating this approach in another territorial context, the Italian one, where abandonment phenomena are widespread. The originality of the contribution lies in correlating aspects usually disconnected, such as technical needs, design, and ecological thinking, to propose an alternative management and redevelopment outlook
Denitrification in a intertidal seagrass meadow, a comparison of 15N isotope and acetylene block technique: dissimilatory nitrate reduction to ammonia as a source of N2O?
No full textTests of the isotope-pairing technique over a range (15-200 μM) of 15N-nitrate additions to the water column of intact or defoliated cores of the seagrass Zostera noltii demonstrated that whilst overall rates of denitrification were highly dependent on the nitrate concentration in the water column, the calculated in situ rates, D14, DW and DN, were not significantly affected. Rates of coupled nitrification-denitrification determined following additions of 15N-ammonium to the sediment porewater were within the range of DN values determined by isotope pairing. Thus, this technique appears to accurately measure denitrification rates in these seagrass-colonised sediments, probably due to the effective limitation of coupled nitrification-denitrification to the surficial sediments, which ensures the homogenous mixing within the denitrification zone of the added 15N- nitrate tracer and the 14N-nitrate generated by nitrification in the sediment. Denitrification rates of nitrate diffusing from the water column were compared using the isotopepairing and acetylene-block techniques. Whilst rates were similar during dark incubations, during light incubations, rates of N2O accumulation during acetylene blocking were consistently twofold greater than denitrification rates measured by isotope pairing. We propose that this excess N2O could have been generated during dissimilatory nitrate reduction to ammonium by fermentative and or sulphate-reducing bacteria
Buoyancy-Driven Chemohydrodynamic Patterns in A + B → Oscillator Two-Layer Stratifications
No full textChemohydrodynamic patterns due to the interplay of buoyancy-driven instabilities and reaction-diffusion patterns are studied experimentally in a vertical quasi-two-dimensional reactor in which two solutions A and B containing separate reactants of the oscillating Belousov-Zhabotinsky system are placed in contact along a horizontal contact line where excitable or oscillating dynamics can develop. Different types of buoyancy-driven instabilities are selectively induced in the reactive zone depending on the initial density jump between the two layers, controlled here by the bromate salt concentration. Starting from a less dense solution above a denser one, two possible differential diffusion instabilities are triggered depending on whether the fast diffusing sulfuric acid is in the upper or lower solution. Specifically, when the solution containing malonic acid and sulfuric acid is stratified above the one containing the slow-diffusing bromate salt, a diffusive layer convection (DLC) instability is observed with localized convective rolls around the interface. In that case, the reaction-diffusion wave patterns remain localized above the initial contact line, scarcely affected by the flow. If, on the contrary, sulfuric acid diffuses upward because it is initially dissolved in the lower layer, then a double-diffusion (DD) convective mode develops. This triggers fingers across the interface that mix the reactants such that oscillatory dynamics and rippled waves develop throughout the whole reactor. If the denser solution is put on top of the other one, then a fast developing Rayleigh-Taylor (RT) instability induces fast mixing of all reactants such that classical reaction-diffusion waves develop later on in the convectively mixed solutions
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