141 research outputs found

    Analysis of sustainability in the pig production chain : life cycle assessment of contrasting scenarios

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    This research investigated the environmental impact of the pig production chain by modelling contrasting scenarios. Life Cycle Analysis (LCA) and scenario analysis methodologies were used to reveal the main opportunities to improve sustainability. Pig production systems were modelled in two countries (The UK and Mexico), each with a standard production system and on alternative system. This gave four scenarios which were different in the degree of integration that exist between pig and crop production and were then specified in detail to allow for comparison of environmental impact. This study used two strategies to analyse the four scenarios: A pre-assessment facilitated the construction of the system boundary and clarified the processes and commodities which should be included in the Life Cycle Inventory (LCI). A hybrid-LCA method combined a detailed collection of environmental burdens (e-burdens) from the main sources (process-LCA) and a broad compilation of e-burdens from indirect sources (Economic Input Output-LCA). The pre-assessment, conducted as a general LCA, explored novel techniques to construct the system boundary and explore the supply chains in detail. This step clarified the importance of the supply chains of different commodities that are used in the pig farm. The importance of previously reported commodities and processes that mainly contribute to the environmental impact, i.e. feed consumption and manure fermentation were confirmed. Novel findings included the importance of the environmental impacts of goods and services, i.e. machinery, equipment, disinfectants and medicines, that have negligible weight in the impact of environmental indicators that are traditionally analysed (global warming, acidification and eutrophication). The inclusion of novel indicators, such as ozone depression and ecotoxicity to water and soil, demonstrated the importance of including in the LCA those commodities and indicators that have been excluded in many previous studies on the sustainability of pig production. Subsequently, the hybrid-LCA method allowed the expansion of the system boundary of the LCA in a detailed evaluation of each scenario. Results showed the UK scenarios to be superior in management of nutrient flow, by manure management and good agricultural practice. Opportunities to capture methane and recycle nutrients for crop production in the Mexican scenarios were highlighted. In contrast, reduction in machinery and equipment use and fuel consumption were the main opportunities which emerged for the UK scenarios. In addition, specific opportunities to reduce the environmental impact of different pig supply chain sectors were identified in each scenario. In conclusion, the EIO-LCA method allowed for an extension of the traditional system boundary of the LCA, to encompass those e-impacts that have not been included in previous studies. The contrasting of different scenarios allowed emphasis to be placed on opportunities to reduce environmental impact of pig production by highlighting the main challenges in each case. This avoids the controversial issue of denoting a set of specific e-impacts that then favour one production system over another.EThOS - Electronic Theses Online ServiceNational Autonomous University of Mexico (UNAM) : DGAPAGBUnited Kingdo

    Conversion of High Biomass/Bagasse from Sorghum and Bermuda Grass into Second-Generation Bioethanol

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    Sorghum (Sorghum bicolor) and Bermuda (Cynodon dactylon) grass are examples of annual and perennial forage crops produced throughout the globe. These crops should be harvested at the peak of biomass production when the levels of lignin are relatively low. The high biomass sorghum, sweet sorghum bagasse (2 cuts or crops year−1) or Bermuda grass capable of yielding up to 50, 60 and 27 tons of dry forage ha−1 year−1 rich in cellulose and hemicellulose can be efficiently transformed into bioethanol using second-generation technologies consisting of milling, pretreatment (chemical and/or enzymatic) and fermentation with microorganisms capable of transforming C5/C6 sugars to obtain ethanol. An alternative process contemplates the extrusion aimed toward the physical disruption of cell walls minimizing the use of considerable amounts of water and chemicals commonly used during pretreatment. Extruded feedstocks treated with fiber-degrading enzyme cocktails had conversion efficiencies between 60 and 78% of the hemicellulose and cellulose similar to the ones achieved after acid/enzyme hydrolyses. The chief advantages of this continuous process are that hydrolysates are practically free of enzymes and yeast inhibitors. These feedstocks can produce up to 310 L anhydrous bioethanol dry t−1 and have a great potential for widespread use

    The estrogenicity of bisphenol A-related diphenylalkanes with various substituents at the central carbon and the hydroxy groups

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    This work was reported in part at the meeting Estrogens in the Environment IV: Linking Fundamental Knowledge, Risk Assessment, and Public Policy held in Washington, DC, 19-21 July 1997.The chemical structure of hydroxylated diphenylalkanes or bisphenols consists of two phenolic rings joined together through a bridging carbon. This class of endocrine disruptors that mimic estrogens is widely used in industry, particularly in plastics. Bisphenol F, bisphenol A, fluorine-containing bisphenol A (bisphenol AF), and other diphenylalkanes were found to be estrogenic in a bioassay with MCF7 human breast cancer cells in culture (E-SCREEN assay). Bisphenols promoted cell proliferation and increased the synthesis and secretion of cell type-specific proteins. When ranked by proliferative potency, the longer the alkyl substituent at the bridging carbon, the lower the concentration needed for maximal cell yield; the most active compound contained two propyl chains at the bridging carbon. Bisphenols with two hydroxyl groups in the para position and an angular configuration are suitable for appropriate hydrogen bonding to the acceptor site of the estrogen receptor. Our data suggest that estrogenicity is influenced not only by the length of the substituents at the bridging carbon but also by their nature. Because diphenylalkane derivatives are widespread and their production and use are increasing, potential exposure of humans to estrogenic bisphenols is becoming a significant issue. The hazardous effects of inadvertent exposure to bisphenol-releasing chemicals in professional workers and the general populations therefore deserve investigation.This research was supported by grants from the Spanish Ministry of Health (FIS, 95/1959) and the Andalusian Regional Government Department of Health (Consejerla de Salud, 96/159)

    Serendipitous discovery of the long-sought AGN in Arp 299-A

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    Context: The dusty nuclear regions of luminous infra-red galaxies (LIRGs) are heated by either an intense burst of massive star formation, an active galactic nucleus (AGN), or a combination of both. Disentangling the contribution of each of those putative dust-heating agents is a challenging task, and direct imaging of the innermost few pc can only be accomplished at radio wavelengths, using very high-angular resolution observations. Aims: We observed the nucleus A of the interacting starburst galaxy Arp 299, using very long baseline interferometry (VLBI) radio observations at 1.7 and 5.0 GHz. Our aim was to characterize the compact sources in the innermost few pc region of Arp 299-A, as well as to detect recently exploded core-collapse supernovae. Methods: We used the European VLBI Network (EVN) to image the 1.7 and 5.0 GHz compact radio emission of the parsec-scale structure in the nucleus of Arp 299-A with milliarcsecond resolution. Results: Our EVN observations show that one of the compact VLBI sources, A1, previously detected at 5.0 GHz, has a flat spectrum between 1.7 and 5.0 GHz and is the brightest source at both frequencies. Our 1.7 GHz EVN image shows also diffuse, low-surface brightness emission extending westwards from A1 and displays a prominent core-jet structure. Conclusions: The morphology, radio luminosity, spectral index and ratio of radio-to-X-ray emission of the A1-A5 region is consistent with a low-luminosity AGN (LLAGN), and rules out the possibility that it is a chain of young radio supernovae (RSNe) and supernova remnants (SNRs). We therefore conclude that A1-A5 is the long-sought AGN in Arp 299-A. This finding may suggest that both starburst and AGN are frequently associated phenomena in mergers.Comment: Accepted for publication in Letters to Astronomy and Astrophysics on 12 August 2010. 4 pages, 1 figur

    Experimental verification of intermediate band formation on titanium-implanted silicon

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    Intermediate band formation on silicon layers for solar cell applications was achieved by titanium implantation and laser annealing. A two-layer heterogeneous system, formed by the implanted layer and by the un-implanted substrate, was formed. In this work, we present for the first time electrical characterization results which show that recombination is suppressed when the Ti concentration is high enough to overcome the Mott limit, in agreement with the intermediate band theory. Clear differences have been observed between samples implanted with doses under or over the Mott limit. Samples implanted under the Mott limit have capacitance values much lower than the un-implanted ones as corresponds to a highly doped semiconductor Schottky junction. However, when the Mott limit is surpassed, the samples have much higher capacitance, revealing that the intermediate band is formed. The capacitance increasing is due to the big amount of charge trapped at the intermediate band, even at low temperatures. Ti deep levels have been measured by admittance spectroscopy. These deep levels are located at energies which vary from 0.20 to 0.28?eV below the conduction band for implantation doses in the range 1013-1014 at./cm2. For doses over the Mott limit, the implanted atoms become nonrecombinant. Capacitance voltage transient technique measurements prove that the fabricated devices consist of two-layers, in which the implanted layer and the substrate behave as an n+/n junction

    Multiwavelength study of the starburst galaxy NGC7714. I: Ultraviolet-Optical spectroscopy

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    We have studied the physical conditions in the central 300 pc of the proto-typical starburst galaxy NGC 7714. Our analysis is based on ultraviolet spectroscopy with the HST+GHRS and ground-based optical observations.The data are interpreted using evolutionary models optimized for young starburst regions. The massive stellar population is derived in a self-consistent way using the continuum and stellar absorption lines in the ultraviolet and the nebular emission line optical spectrum. The central starburst has an age of about 4.5 Myr, with little evidence for an age spread. Wolf-Rayet features at the ultraviolet indicates a stellar population of \sim 2000 Wolf-Rayet stars. The overall properties of the newly formed stars are quite similar to those derived, e.g., in 30 Doradus. A standard Salpeter IMF is consistent with all observational constraints. We find evidence for spatial structure within the central 300 pc sampled. Therefore it is unlikely that the nucleus of NGC 7714 hosts a single star cluster exceeding the properties of other known clusters. Contrary to previous suggestions, we find no evidence for a nuclear supernova rate that would significantly exceed the total disk-integrated rate. About one supernova event per century is predicted.Comment: 19 pages, 9 figures in a tar file. Accepted for publication in ApJ, 1999, March, issue 51

    Ovarían morphology andfolliculogenesis in Gymnotus carapo (Linnaeus, 1758)

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    El objetivo del presente trabajo fue el estudio de la morfología ovárica y la foliculogénesis de Gymnotus carapo, a fin de aportar información sobre su biología reproductiva, y que ésta sea de utilidad en el manejo de dicha especie como recurso pesquero. Se recolectaron 40 ejemplares hembras durante el periodo de febrero a diciembre del 2019 en ambientes naturales próximos a la Ciudad de Corrientes. Posteriormente a la captura fueron anestesiados con solución de lidocaína al 2% y sacrificados por sección medular. Los ovarios fueron aislados y fijados en formol al 10%; posteriormente fueron procesados para la técnica histológica convencional y coloreados con hematoxilina-eosina (H-E), tricrómica de Gomori y reacción histoquímica de PAS. Los preparados histológicos fueron analizados a través del microscopio óptico. Se pudo observar que la foliculogénesis en G. carapo es similar a la descrita para otros peces. El ovario y los ovocitos de G. carapo experimentan diferentes etapas de desarrollo: crecimiento primario, secundario, vitelogénesis y maduración durante el ciclo reproductivo, información que sienta base para estudios futuros sobre biología reproductiva. La información brindada en el presente trabajo es importante dado que aporta un estudio histológico detallado que describe la morfología ovárica y foliculogénesis en G. carapo y contribuye a la gestión y planificación de conservación de especies de importancia para el recurso pesquero.The objective of this work is to study the ovarian morphology and folliculogenesis of Gymnotus carapo, in order to provide information on its reproductive biology, and that this is useful in the management of this species as a fishing resource. 40 female specimens were collected during the period from February to December 2019 from natural environments near the City of Corrientes. After capture, they were anesthetized with 2% lidocaine solution and sacrificed by spinal section. The ovaries were isolated and fixed in 10% formalin; Later they were processed for the conventional histological technique and stained with hematoxylin-eosin (H-E), Gómori trichrome and PAS histochemical reaction. The histological preparations were analyzed through the light microscope. It was observed that the folliculogenesis in G. carapo is similar to that described for other fish. The ovary and oocytes of G. carapo undergo different stages of development: primary and secondary growth, vitellogenesis and maturation during the reproductive cycle, information that provides the basis for future studies on reproductive biology. The information provided in this work is important since it provides a detailed histological study that describes the ovarian morphology and folliculogenesis in G. carapo and contributes to the management and conservation planning of species that are of importance to the fishing resource.Fil: Perez, Dante David. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; ArgentinaFil: Olea, Gabriela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; Argentina. Universidad Nacional del Nordeste. Facultad de Medicina; Argentina. Universidad Nacional del Chaco Austral; ArgentinaFil: Mendez Galarza, Sabrina. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; ArgentinaFil: Blanco Cohene, Tania Katherina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; ArgentinaFil: Flores Quintana, Carolina Isabel. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; Argentina. Universidad Nacional del Chaco Austral; Argentin

    Ovarían morphology andfolliculogenesis in Gymnotus carapo (Linnaeus, 1758)

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    El objetivo del presente trabajo fue el estudio de la morfología ovárica y la foliculogénesis de Gymnotus carapo, a fin de aportar información sobre su biología reproductiva, y que ésta sea de utilidad en el manejo de dicha especie como recurso pesquero. Se recolectaron 40 ejemplares hembras durante el periodo de febrero a diciembre del 2019 en ambientes naturales próximos a la Ciudad de Corrientes. Posteriormente a la captura fueron anestesiados con solución de lidocaína al 2% y sacrificados por sección medular. Los ovarios fueron aislados y fijados en formol al 10%; posteriormente fueron procesados para la técnica histológica convencional y coloreados con hematoxilina-eosina (H-E), tricrómica de Gomori y reacción histoquímica de PAS. Los preparados histológicos fueron analizados a través del microscopio óptico. Se pudo observar que la foliculogénesis en G. carapo es similar a la descrita para otros peces. El ovario y los ovocitos de G. carapo experimentan diferentes etapas de desarrollo: crecimiento primario, secundario, vitelogénesis y maduración durante el ciclo reproductivo, información que sienta base para estudios futuros sobre biología reproductiva. La información brindada en el presente trabajo es importante dado que aporta un estudio histológico detallado que describe la morfología ovárica y foliculogénesis en G. carapo y contribuye a la gestión y planificación de conservación de especies de importancia para el recurso pesquero.The objective of this work is to study the ovarian morphology and folliculogenesis of Gymnotus carapo, in order to provide information on its reproductive biology, and that this is useful in the management of this species as a fishing resource. 40 female specimens were collected during the period from February to December 2019 from natural environments near the City of Corrientes. After capture, they were anesthetized with 2% lidocaine solution and sacrificed by spinal section. The ovaries were isolated and fixed in 10% formalin; Later they were processed for the conventional histological technique and stained with hematoxylin-eosin (H-E), Gómori trichrome and PAS histochemical reaction. The histological preparations were analyzed through the light microscope. It was observed that the folliculogenesis in G. carapo is similar to that described for other fish. The ovary and oocytes of G. carapo undergo different stages of development: primary and secondary growth, vitellogenesis and maturation during the reproductive cycle, information that provides the basis for future studies on reproductive biology. The information provided in this work is important since it provides a detailed histological study that describes the ovarian morphology and folliculogenesis in G. carapo and contributes to the management and conservation planning of species that are of importance to the fishing resource.Fil: Perez, Dante David. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; ArgentinaFil: Olea, Gabriela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; Argentina. Universidad Nacional del Nordeste. Facultad de Medicina; Argentina. Universidad Nacional del Chaco Austral; ArgentinaFil: Mendez Galarza, Sabrina. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; ArgentinaFil: Blanco Cohene, Tania Katherina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; ArgentinaFil: Flores Quintana, Carolina Isabel. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias. Departamento de Cs.basicas. Cátedra de Histología y Embriologia; Argentina. Universidad Nacional del Chaco Austral; Argentin

    Herd-level risk factors of bovine tuberculosis in England and Wales after the 2001 foot-and-mouth disease epidemic

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    We present the results of a 2005 case–control study of bovine tuberculosis (bTB) breakdowns in English and Welsh herds. The herd management, farming practices, and environmental factors of 401matched pairs of case and control herds were investigated to provide a picture of herd-level risk factors in areas of varying bTB incidence. A global conditional logistic regression model, with region-specific variants, was used to compare case herds that had experienced a confirmed bTB breakdown to contemporaneous control herds matched on region, herd type, herd size, and parish testing interval. Contacts with cattle from contiguous herds and sourcing cattle from herds with a recent history of bTB were associated with an increased risk in both the global and regional analyses. Operating a farm over several premises, providing cattle feed inside the housing, and the presence of badgers were also identified as significantly associated with an increased bTB risk. Steps taken to minimize cattle contacts with neighboring herds and altering trading practices could have the potential to reduce the size of the bTB epidemic. In principle, limiting the interactions between cattle and wildlife may also be useful; however this study did not highlight any specific measures to implement
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