2,374 research outputs found

    Testing the Peculiar Velocity Field predicted from Redshift Surveys

    Full text link
    The reconstruction of the peculiar velocity field from the 1.936~Jy iras selected sample of galaxies is compared to a similar reconstruction from an optically selected sample. A general method for combining different samples to reconstruct a self-consistent density and peculiar velocity field is presented. The method is applied to determine how sensitive the derived peculiar velocity field is to the characteristics of the sample used. The possibility that the iras galaxies do not trace the general galaxy population is explored adopting a simple model of linear biasing between the iras and optical samples. We find that the velocity fields derived from the two samples are consistent, within the estimated shot noise error, for the case of no relative bias. This result suggests that the predicted peculiar velocity field based on iras samples is not sensitive to the sampling properties of iras galaxies. Combined with previous suggestion of a relative biasing of iras galaxies on small scales (about 5 h^-1Mpc), this result suggests scale dependent biasing.Comment: tar-compressed and uudecoded postscript files, 12 pages+8 figure

    Using full-scale duckweed ponds as the finish stage for swine waste treatment with a focus on organic matter degradation

    Get PDF
    Artigo Publicado em: IWA - Water Science & TechnologyThe rapid increase in the number of swine has caused pronounced environmental impacts worldwide, especially on water resources. As an aggregate, smallholdings have an important role in South American pork production, contributing to the net diffusion of pollution. Thus, duckweed ponds have been successfully used for swine waste polishing, mainly for nutrient removal. Few studies have been carried out to assess organic matter degradation in duckweed ponds. Hence, the present study evaluated the efficiency of two full-scale duckweed ponds for organic matter reduction of swine waste on small pig farms. Duckweed ponds, in series, received the effluent after an anaerobic biodigester and storage pond, with a flow rate of 1 m3 day 1. After 1 year of monitoring, an improvement in effluent quality was observed, with a reduction in biochemical oxygen demand (BOD) and total chemical oxygen demand (tCOD), respectively, of 94.8 and 96.7%, operating at a loading rate of approximately 27 kgBOD ha 1 day 1 and 131 kgCOD ha 1 day 1. Algae inhibition due to duckweed coverage was strongly observed in the pond effluent, where chlorophyll a and turbidity remained below 25 μg L 1 and 10 NTU. Using the study conditions described herein, duckweed ponds were shown to be a suitable technology for swine waste treatment, contributing to the environmental sustainability of rural areas

    Mechanistic insights into the electrochemical reduction of CO2 to CO on Ni(salphen) complexes

    Get PDF
    LA/P/0056/2020. The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project No 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). FCT is acknowledged for PTDCQUI-QIN0252_2021 (PNM). The CARISMA COST action CM1205 is acknowledged. MJC thanks N. A. G. Bandeira for technical assistance. The CATSUS doctoral programme is also acknowledged. Publisher Copyright: © 2023 The Royal Society of Chemistry.Cyclic voltammetry and bulk electrolysis showed that [Ni(ii)(salphen)] [1], [Ni(ii)(tBu-salphen)] [2], and a binuclear Ni(ii) compound combining salphen and tBu-salphen [3] react with CO2 to yield a metal-carbonyl species that is stable under an oxygen free atmosphere. Upon exposure to air, a stoichiometric amount of CO is released (detected by gas chromatography) and protonation regenerates the initial complex. To shed light on the mechanism of CO2 reduction and O2-dependent CO release by [1], UV-vis, EPR and SEC-IR spectroscopy studies complemented with DFT calculations were performed. It is proposed that the mono reduced [Ni(i)(salphen)]−, 2[1]−, formed a CO2 complex, 2[1(CO2)]−, which was then further reduced to 3[1(CO2)]2−. After addition of two protons, the coordinated CO2 was reduced to CO and released, regenerating 1[1]. Alternatively, 2[1(CO2)]− is protonated and then reduced to the same intermediate as before, continuing the same way. In the second cycle, the CO released competed with CO2 and coordinated to 2[1]− much more strongly, thereby deactivating the system. The new 2[1(CO)]− was reduced to 3[1(CO)]2− which was identified by comparison of experimental spectroscopic (UV-vis, EPR, SEC-IR) data with DFT calculated parameters.publishersversionpublishe

    A pesca de polvos e lulas no litoral do Rio de Janeiro

    Get PDF

    The role of transaction costs in the delivering of urban infrastructure services: an overview of brazilian and portuguese municipalities

    Get PDF
    The present paper explores the different options for delivering public services by Portuguese and Brazilian municipalities. With reduction of human and financial resources and increase in demand, large municipalities need efficient arrangements to deliver public services. In fact, the conditions for providing these services influence the quality of life, the economic development and are directly related to the capacity of institutions to find the most appropriate governance mechanisms. In this context, the use of Transaction Costs Theory (TCT), specifically economic and political costs, reveals an appropriated tool to understand the ways how public services can be delivered. Existing research and theory point out several studies around the world that analyze how different governance mechanism’s choice (hierarchy, market and network) can be explained based on TCT. This paper contributes to expand this topic to Brazilian’s municipalities context, due to the lack of studies in this country. Contrariwise, there are more studies about Portuguese’s municipalities, but as a dynamic process, it’s becomes interesting update such studies in order to expand the existing database. In this sense we addressed a preliminary step whose objective is to identify the different options for public service delivery, finding similarities and differences in these two countries, following a qualitative approach. As results, we find that governance mechanisms adopted by two countries are very similar. The differences result from regional level in Brazil that allows recourse to state's business sector, as opposed to Portugal. In turn, Portuguese municipalities have several options that result from municipal associations, options that are more limited in Brazilian case.info:eu-repo/semantics/publishedVersio

    Gender in their attitude towards domestic violence and intimate partner violence in Portugal

    Get PDF
    ESA 2021. 15ª Conferência realizada em Barcelona de 31 de agosto a 3 setembro de 2021.info:eu-repo/semantics/publishedVersio

    Estimation of moisture in wood chips by near infrared spectroscopy

    Get PDF
    In order to assess the moisture content of wood chips on an industrial scale, readily applicable techniques are required. Thus, near infrared (NIR) spectroscopy was used to estimate moisture in wood chips by means of partial least squares regressions. NIR spectra were obtained in spectrometer with an integrating sphere and optical fiber probe, on the longitudinal and transverse surface of Eucalyptus wood chips. The specimens had their masses and NIR spectra measured in 10 steps during drying from saturated to anhydrous condition. Principal Component Analysis was performed to explore the effect of moisture of wood chip on NIR signatures. The values of moisture content of chips were associated with the respective NIR spectra by Partial Least Squares Regression (PLS-R) and Partial Least Squares Discriminant Analysis (PLS-DA) to estimate the moisture content of wood chips and its moisture classes, respectively. Model developed from spectra recorded on the longitudinal face by the integrating sphere method presented statistics slightly better (R²cv = 0,96; RMSEcv = 7,15 %) than model based on optical fiber probe (R²cv = 0,90; RMSEcv = 11,86 %). This study suggests that for calibration of robust predictive model for estimating moisture content in chips the spectra should be recorded on the longitudinal surface of wood using the integrating sphere acquisition method
    • …
    corecore