136,197 research outputs found
Choice Experiments in Enviromental Impact Assessment: The Toro 3 Hydroelectric Project and the Recreo Verde Tourist Center in Costa Rica
No full textChoice experiments, a stated preference valuation method, are proposed as a tool to assign monetary values to environmental externalities during the ex-ante stages of environmental impact assessment. This case study looks at the impacts of the Costa Rican Institute of Electricity’s Toro 3 hydroelectric project and its affects on the Recreo Verde tourism center in San Carlos, Costa Rica. Compared to other valuation methods (e.g., travel cost and contingent valuation), choice experiments can create hypothetical but realistic scenarios for consumers and generate restoration alternatives for the affected good. Although they have limitations that must be taken into account in environmental impact assessments, incorporating economic parameters—especially resource constraints and tradeoffs—can substantially enrich the assessment process.stated-preference, economic valuation, choice experiments, hydropower, tourism, Costa Rica
Optimización de parámetros para la extracción de elementos desde minerales en medios ácido
No full text[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Actualmente, la gran minería del cobre chilena se encuentra frente a nuevos problemas y desafíos a superar. El principal problema, es de carácter medio ambiental, debido a que la mayor parte de la producción es por procesos de flotación, lo que implica aumentar la generación de relaves, ocasionando drenajes ácidos que generan la movilidad de elementos pesados al medio ambiente. Otro desafío importante, es diversificar las extracciones de otros elementos (como ocurre actualmente con el molibdeno) para impulsar la exportación de productos básicos y aumentar el empleo. Además, se deben tratar recursos que hoy en día no se están aprovechando a escala industrial, un ejemplo son los minerales de cobre negro, estos recursos generalmente no se incorporan en las pilas de lixiviación. Estos minerales exóticos tienen cantidades considerables de Mn (aproximadamente 29%), lo que representa un atractivo comercial. Para abordar este desafío, se realizaron investigaciones a nivel laboratorio, de extracción de cobre y manganeso desde cobres negros mediante procesos de lixiviación. Se evaluaron diferentes aditivos y concentraciones de estos mediante la aplicación de modelos estadísticos de regresión cuadrática, evaluando efectos lineales, interacciones y curvaturas. Además, se diseñaron y probaron con éxito nuevos procesos de extracción. Finalmente, se pudo demostrar que para la disolución de Mn ya sea desde nódulos marinos o cobres negros, se obtienen resultados positivos al adicionar Fe en el sistema, siendo un parámetro óptimo de trabajo una razón de MnO2/Fe de 1/2, logrando extracciones sobre el 70% en tiempos de 20 min. Para la disolución de Cu desde sulfuros secundarios, se puede concluir que los mejores resultados se obtienen al trabajar a elevadas concentraciones de cloruro, siendo poco relevante la concentración de H2SO4. Por otra parte, para la disolución de calcopirita, trabajar en un medio clorurado incorporando altas concentraciones de MnO2 (razones de MnO2/CuFeS2 de 5/1) favorece el mantener un alto valor de potencial en el sistema, superando la pasivación de este mineral.[ENG] This doctoral dissertation has been presented in the form of thesis by publication. Currently, the great copper mining is facing new problems and challenges to overcome. The main problem is environmental, because most of the production is due to flotation processes, which implies increasing the generation of tailings, causing acid drains that generate the mobility of heavy elements to the environment. Another important challenge is to diversify the extractions of other elements (as is currently the case with molybdenum) to boost the export of basic products and increase employment. In addition, resources that are not currently being used on an industrial scale should be treated, an example is black copper ores, these resources are generally not incorporated into the extraction circuits or are not treated, whether in stocks, platforms leaching or waste. These exotic minerals have considerable amounts of Mn (approximately 29%), which represents a commercial appeal. To address this challenge, research was carried out at the laboratory level, for the extraction of copper and manganese from minerals through leaching processes. Evaluating different additives and concentrations thereof, applying the use of statistical models of quadratic regression, evaluating linear effects, interactions and curvatures. And in other cases, creating new extraction processes. Finally, it was discovered that for the dissolution of Mn either from marine nodules or black copper, very positive results are obtained by adding Fe in the system, an optimal working parameter being a ratio of MnO2/Fe of 1/2, achieving extractions above 70% in times of 20 min. For the dissolution of Cu from secondary sulphides, it was found that the best results are obtained when working at high concentrations of chloride, the concentration of H2SO4 being insignificant. On the other hand, for the dissolution of chalcopyrite, working in a chlorinated medium incorporating high concentrations of MnO2 (ratios of MnO2 / CuFeS2 of 5/1) favors maintaining a high potential value in the system, overcoming the passivation of this mineral.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaPrograma de Doctorado en Tecnología y Modelización en Ingeniería Civil, Minera y AmbientalScientific Equipment Unit- MAINI of the Universidad Católica del Norte (Chile)Los artículos que componen la tesis son los siguientes: Publicación 1: N. Toro*, M. Saldaña, E. Gálvez, M. Cánovas, E. Trigueros, J. Castillo and P. Hernández. “Optimization of Parameters for the Dissolution of Mn from Manganese Nodules with the Use of Tailings in an Acid Medium” Q2 ISI WoS. Minerals, 2019; https://doi.org/10.3390/min9070387. Publicación 2: N. Toro*, W. Briceño, K. Pérez, M. Cánovas, E. Trigueros, R. Sepúlveda and P. Hernández. “Leaching of Pure Chalcocite in a Chloride Media Using Sea Water and Waste Water” Q1 ISI WoS. Metals, 2019; https://doi.org/10.3390/met9070780. - Publicación 3: M. Saldaña, N. Toro*, J. Castillo, P. Hernández, E. Trigueros, and A. Navarra. “Development of an Analytical Model for the Extraction of Manganese from Marine Nodules” Q1 ISI WoS. Metals, 2019 https://doi.org/10.3390/met9080903. - Publicación 4: N. Toro*, K. Pérez, M. Saldaña, R. I. Jeldres, M. Jeldres and M. Cánovas. “Dissolution of pure chalcopyrite with manganese nodules and waste water” Q1 ISI WoS. Journal of Materials Research and Technology, 2019 https://doi.org/10.1016/j.jmrt.2019.11.020. - Publicación 5 (En Revisión): N. Toro*, W. Briceño, A. Navarra, K. Pérez, M. Cánovas and E. Trigueros. “Statistical and kinetic study for leaching of covellite in a chloride media” Q1 ISI WoS. Journal of Materials Research and Technology.Universidad Politécnica de Cartagen
Defying the law, negotiating change The Futanke’s opposition to the national ban on FGM in Senegal
No full textThis thesis is concerned with the politics of the preservation and ‘abandonment’ of female circumcision in Fouta Toro, Senegal. The focal point of analysis is the overt opposition to the law criminalising female genital cutting in 1999, and development projects raising awareness about excision in human rights and reproductive health education programmes. As an ethnography of the politics around bodily practices in the light of governmental and non-governmental intervention, the thesis looks at how different interest groups justify their position towards excision. This is a timely enquiry, given the Senegalese government’s ‘acceleration programme of the complete abandonment of excision by 2015’ and some Futanke leaders’ non-compliance with, and opposition to this intervention.
After providing details about ‘the ban’ on ‘female genital mutilation’ in Senegal and a critical reflection on the events that are seen to have led to the call for this ban, I carefully disentangle what ‘the opposition to the law’ is and who disagrees with ‘the abandonment’ of the practice in Fouta Toro. The central part of the thesis is guided by an analysis of how excision is embedded in constructions of personhood, sociality and ethnic identity, and how the body is imagined and located in this process. I show how conceptions of ethnic purity and pride are formulated in terms of fear about a ‘loss of culture’ and ‘foreign invasion’ which nourishes discourses of opposition to the law and non-governmental intervention. Others use ‘human rights’ associated with non-governmental organisations and the state as a vehicle to express their views against excision and those who oppose its criminalisation. I examine how idioms like ‘the state’, ‘human rights’ and ‘Futanke way of life’ feature in discourses around the ban of excision in Fouta Toro, and how respectability and honour are maintained through competing representations of the female body as a site of morality. Some claim the female body – a reproducer of cultural identities – with reference to duties through kin obligations, others with reference to ‘human rights’ and ‘the state’.
Based on 15 months’ ethnographic fieldwork in Fouta Toro and nine years working in and researching the impact of development in Senegal, this dissertation contributes to scholarship on Fouta Toro and indicates how governmental and non-governmental intervention stirs up the caste-related power structures of a society led by the Tooroɓɓe since the Islamic revolution in the 18th century. It shows how the female body is located as a site of morality, key to the reproduction of cultural identities
The helicase-like domain from "Thermotoga maritima" reverse gyrase : catalytic cycle and contribution to DNA supercoiling
No full textReverse gyrases are the only topoisomerases capable of introducing positive supercoils into circular DNA. Their exclusive presence in thermophilic and hyperthermophilic organisms indicates a DNA thermoprotective role in vivo. In spite of the efforts to improve our knowledge of reverse gyrase, modest progress has been made since its discovery. Currently, only one crystal structure of the enzyme is available, and the most widely accepted reaction mechanism is a hypothetical one, mostly derived from the functions of enzymes related to reverse gyrase domains.
In the present work we address mechanistic aspects of the reaction by exploiting the capabilities of a wide range of techniques, to elucidate the role of one module of T. maritima reverse gyrase. Reverse gyrase consists of an N-terminal helicase-like domain, fused to a C-terminal topoisomerase domain. We selected the helicase-like domain as a model of study due to its capacity to couple ATP binding and hydrolysis to DNA processing. Exploiting of these features by reverse gyrase turns this region into a key player at virtually every step of DNA supercoiling.
Steady-state ATPase assays and equilibrium binding titrations with the helicase-like domain and the full-length enzyme, enabled us to prove for the first time a harnessing effect of the topoisomerase over the helicase-like domain. We showed that properties intrinsic to the helicase-like domain, like DNA-stimulated ATP hydrolysis, nucleotide-dependent affinity switch for DNA, and thermodynamic coupling between DNA binding and ATP binding and hydrolysis, are strongly reduced in the context of reverse gyrase. At that time apparent contradictions arose, from reports stating that the isolated helicase-like domain is less active than within the context of the full-length enzyme. We reconciled these differences by demonstrating that the presence of the putative N-terminal Zn-finger in the helicase-like domain construct is the cause for the decreased activity. Furthermore, we have elucidated the thermodynamic and conformational cycle of the helicase-like domain, and predicted the stages fulfilling the requirements for interdomain communication, local duplex DNA unwinding, and the stages where DNA is in a suitable state to support the supercoiling reaction. Finally, besides the use of smFRET as a tool to investigate conformational changes in solution, we have also provided high-resolution snapshots of the helicase-like domain via X-ray crystallography. We have provided the most detailed structures of this region to this date, in the apo and ADP-bound forms. They also revealed high flexibility of the linker joining the RecA domains with relative orientations far from random, and local differences in secondary structure motifs that discard the assumption of all reverse gyrases having a “monolithic” build-up.
We also created a deletion mutant of the latch, region with a sui generis location, perfectly suited for interdomain communication. Previous reports stated that its deletion from reverse gyrase abolishes positive supercoiling. We demonstrated its strong involvement in DNA binding, DNA-stimulated ATP hydrolysis, and thermodynamic coupling between these processes in the isolated helicase-like domain. We also revealed its role in presenting the ssDNA to the topoisomerase domain and in guiding the strand passage and resealing, ensuring the directionality leading to the introduction of positive supercoils. Additionally, we also elucidated the nucleotide cycle and conformational transitions for this helicase-like domain mutant, which gave the first indications of why no positive supercoiling can be performed by the full-length reverse gyrase lacking the latch, and only DNA relaxation is allowed.
Finally, our pre steady-state kinetic studies allowed us to fully describe the unstimulated ATPase activity of the isolated helicase-like domain. We also demonstrated for the first time its DNA unwinding activity, shedding light on the rarely documented local B-DNA duplex destabilization of helicase-like modules, appended to bigger enzymes. Additionally, the sequence of ssDNA strand release, and identification of secondary structure motifs involved in ssDNA binding at different stages were determined. Together with the finding of new conformational states via smFRET, and “targeted” supercoiling assays with the full-length enzyme, we end up proposing a detailed catalytic mechanism, similar to the one derived from the reverse gyrase structure, only this time based on and supported by a combination of kinetic, thermodynamic, and structural data
Ruptiliocarpon caracolito Hammel & N. Zamora from Colombia collected by F. Toro, E. Álvarez, A. Camargo #256
No full textFile Name: TOLI-22407-ZAR-05-300.jpg
CÓDIGO FOTO: TOLI-22407-ZAR-05-300-
Fotografía: SI
Nº TOLI: TOLI-22407
PARCELA: ZAR-05
CÓDIGO: 300
Nº COLECTA: 256
NUEVOS COLECTORES: Alejandro Camargo, Felipe Toro & Esteban Alvarez
COLECTORES: F. Toro, E. Álvarez, A. Camargo
Nº MUESTRAS MONTADAS: 2
Homologación: No homologado
Nueva fecha del evento : 30/11/2018.
Fecha del evento: 27/04/2019.
Proyecto : Recursos Botánicos Disponibles en Línea (BRAVO) para la flora Colombiana
Hábitat: Bosque húmedo tropical (bh-T)
Comentario del evento: Bosque de tierra firme
Continente: SA
Pais: Colombia
Estado/Provincia: Amazonas
Municipio: Leticia
Localidad: Resguardo Indígena Ticuna-Huitoto Km 6-11.
Elevación minima en metros: 200
Elevación maxima en metros: 300
Latitud: -4.004
Longitud original: -69.896
datum geodésico: WGS 84
Latitud decimal: -4.004
Longitud decimal: -69.896
Identificado por: Diego Suescún
Fecha de identificación: 15/02/2019.
Nombre cientifico: Ruptiliocarpon caracolito Hammel & N. Zamora
Reino: Plantae
Filo: Magnoliophyta
Clase: Equisetopsida
Orden: Celastrales
Familia nueva: Lepidobotryaceae
Género nuevo: Ruptiliocarpon
especie nueva: caracolito
Autoría del nombre científico: Hammel & N. Zamora
: Lepidobotryaceae
genero herbario: Ruptiliocarpon
especie herbario: caracolito
Especie de herbario para TNRS: Ruptiliocarpon caracolito
Especie corregida herbario y desde TNRS: Ruptiliocarpon caracolito
Familia corregida desde TNRS: Lepidobotryaceae
: 1540</p
Analysis and comparison of different thermal cycles for power generation in space
No full textThis paper presents an analysis of solar-heat driven Brayton and Rankine power cycles operating in space with different working fluids. State of the art literature show that generation of power in space for terrestrial use can represent a great opportunity in the future for many reasons, including the facts that (1) the lowtemperature of space, - 3K, which acts as the power system heat sink, allows the attainment of very high efficiency even with low-temperature heat inputs, and (2) the solar energy input is higher than on earth, all this while using traditional cycles. This study is focused on analysis and comparison of performance of advanced Brayton and Rankine cycles operating under space conditions, with a main objective to advance the identification of system configurations, working fluids and conditions leading to the design of space power systems that combine high efficiency and low weight. Starting from previous studies that show the potential high efficiency of the use of diatomic gases (H2, N2) in regenerative Brayton and Rankine cycles we have presented a comparative analysis of different and more advanced Brayton and Rankine configurations to advance the understanding of the optimal trade-off between high efficiency (thermal and exergetic) and the smallest needed heat rejection exchanger area. The effect of the main cycles' operational parameters such as pressure ratio, turbine inlet temperature, working fluid mixture and different plant layouts on thermal and exergy efficiency and power to radiator area ratio have been analyzed. Under the examined conditions the thermal efficiency of regenerative - reheated-intercooled Brayton, that resulted being the best Brayton choice, reaches 71.8% while the efficiency of the reheated-regenerative Rankine cycle reaches 88.9%, both significantly higher than the previously analysed cycles taken as reference. The power/(radiator area) ratio, however, was an order of magnitude higher for the reheated-intercooled Brayton cycle, which may lead to lower costs of the generated power. This ratio was also found to increase with the introduction of reheating for both the Rankine and Brayton cycles, while the Interceding was in all cases disadvantageous
[Hércules y el Toro de Creta]
No full textRepresentación del 7º trabajo de Hércules para Euristeo : Poseidón había hecho surgir este toro del seno del mar para que Minos lo ofreciera a los dioses; pero Minos prendado de su hermosura lo guardó. Poseidón mandó entonces al toro una locura furiosa: Hércules logró calmarlo y lo capturó para EuristeoSin fechaSin firm
Une nécropole à l'Age de Bronze à Granada (Espagne)
No full textRamos Manuel, Toro Moyano Isidro, Toro Moyano Lizana. Une nécropole à l'Age de Bronze à Granada (Espagne). In: Bulletin de la Société préhistorique française, tome 85, n°9, 1988. pp. 284-288
Bocas del Toro, Station_Climate Conditions
No full text Bocas del Toro Research Station Manual Rain GaugeLocation: 9° 21.093'N, 82° 15.394'WMorning, subjective weather conditions</p
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