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Structure of a disturbed natural forest of Pinus tropicalis Morelet in Galalón, Cuba
No full text"Los bosques naturales de Pinus tropicalis Morelet en Cuba han sido alterados por prácticas inadecuadas de aprovechamiento forestal. Esta investigación tiene el objetivo de caracterizar la estructura de un bosque perturbado de Pinus tropicalis en Galalón, Pinar del Río. Para ello se realizó un inventario florístico, se determinaron los índices de valor de importancia ecológica y de importancia ecológica ampliado. Se calculó la diversidad alfa mediante el recíproco del índice de Simpson (1/D) y el índice de Jackknife, así como la diversidad beta por medio de Morisita-Horn y Jaccard. Se evaluó el grado de perturbación del área mediante indicadores de cambios en el ecosistema. Se identificaron un total 22 familias, 30 géneros y 31 especies. Los parámetros estructurales indicaron que las especies de mayor importancia ecológica son P. tropicalis, P. caribaea var. caribaea y Byrsonima crassifolia. La diversidad florística se calificó de baja y la similitud resultó en tres grupos diferenciados por su composición florística.""Natural forests of Pinus tropicalis Morelet in Cuba have been altered by inadequate management. The aim of this study was to characterize the structure of a disturbed forest of Pinus tropicalis in Galalón, Pinar del Rio. We carried out a floristic inventory, and determined the ecological importance value and the increased ecological importance index. The alpha diversity was calculated by means of the reciprocal of the Simpson index (1/D) and the Jackknife index. The beta diversity was estimated through the Morisita-Horn and Jaccard. The degree of interference of the area was evaluated by means of indicators of changes in the ecosystem. We identified 30 genera and 31 species from 22 families. The structural parameters indicated that the species of higher ecological importance were P. tropicalis, P. caribaea var. caribaea and Byrsonima crassifolia. The floristic diversity was low and the similarity indexes yielded three groups differing in floristic composition.
Delimitación aeromagnética del Bloque Jalisco. implacaciones geohidrológicas en Tequila, Jalisco
Get PDF"Para este estudio, se plantearon dos objetivos principales, divididos en tres etapas, los cuales se cumplieron utilizando dos métodos geofísicos, el magnético y eléctrico. En el cumplimiento del primer objetivo, el cual es proponer un límite septentrional y oriental para el Bloque Jalisco (BJ), se utilizó la magnetometría aérea, debido a que es posible cubrir una gran extensión de terreno y brinda grandes cantidades de información, además de que es una primera etapa para el reconocimiento geológico. La información aeromagnética fue adquirida del Servicio Geológico Mexicano (SGM) en un formato ascci (X, Y, Z), a la cual se le aplicaron diversos algoritmos matemáticos que nos permitieron definir los lineamientos superficiales y profundos del BJ, seis Dominios Aeromagnéticos (DAM) asociados a diferentes unidades geológicas y definir el límite septentrional y oriental del bloque. El límite del BJ se asocia con movimientos de distención, los cuales a su vez producen un fracturamiento en las rocas, mismos que son asociados con permeabilidades secundarías. En las proximidades del límite norte propuesto, se encuentra Tequila, Jalisco, lugar donde se desarrollaron las etapas de semidetalle y detalle para el cumplimiento del segundo objetivo, mismo que consiste en delimitar zonas con posibilidades acuíferas. Dentro de la etapa de semidetalle se realizaron 41 secciones magnéticas terrestres con dirección E – W, con la información de dichas secciones se generó un mallado al cual se le aplicaron diferentes algoritmos matemáticos para marcar los lineamientos superficiales, intermedios y profundos, así como cinco Dominios Magnéticos (DM). En la etapa de detalle se realizaron 48 Sondeos Eléctricos Verticales (SEV´s), con los que se identificaron las mejores zonas para pozos de extracción de agua.""For this study, two main objectives were proposed, divided into three stages, which were accomplished using two geophysical methods, the magnetic and the electric. In fulfilling the first objective, which is to propose a northern and eastern boundary for the Jalisco Block (JB), aerial magnetometry was used, because it is possible to cover a large terrain extension and provides large amounts of information, besides it is a first stage for the geological reconnaissance. The aeromagnetic data was acquired from the Mexican Geological Survey (SGM) in a ascci format (X, Y, Z), to which various mathematical algorithms were applied that allowed us to define the superficial and deep alignments, six Aeromagnetic Domains (AMD) associated to different geological units and to define the northern and eastern boundary of the block. The limit of the JB is associated with distension movements, which in turn produce fracturing in the rocks, which are themselves associated with secondary permeabilities. In the vicinity of the proposed northern boundary, is Tequila, Jalisco, place where the semi-detailed and detailed stages were developed for the fulfillment of the second objective, which consist in to delineate the areas with aquifer potential. Within the stage of semi-detailed 41 terrestrial magnetic sections were performed in E – W direction, with the information from these sections a mesh was generated for which different mathematical algorithms were applied to mark the superficial, intermediate and deep alignments, as well as five Magnetic Domains (DM). In the detail stage, 48 Vertical Electrical Soundings (VES) were performed, with which the best areas for water extraction wells were identified.
Convertidor CD/CA sin aislamiento con conexión a la red eléctrica para aplicaciones en paneles solares
Get PDF"Para aprovechar la energía solar como energía eléctrica es necesario del uso de paneles solares fotovoltaicos (PV), los cuales aprovechan la radiación proveniente de la actividad solar y convierten la energía solar en energía eléctrica en corriente directa (CD). Para poder utilizar esta tecnología como generadora de electricidad y poder suministrarla en casas, edificios, pozos e iluminación en lugares lejanos entre otros es necesario convertirla de corriente directa a corriente alterna (CA). Para esto se hace uso de convertidores CD/CA (también conocidos como inversores). Muchas de las aplicaciones de estos inversores es cuando son usados para proveer de energía a casas o edificios, en estos casos existen dos modalidades, cuando están aislados de la red eléctrica o cuando están conectados a está. En los casos cuando están conectados a la red eléctrica la mayoría de las topologías existentes presentan una conexión en su salida en modo diferencial, este tipo de conexión ocasiona que circule corriente a través de capacitancias parásitas generadas en las terminales del panel solar. Esta corriente no es deseada en los sistemas generadores de energía por medio de paneles solares ya que no solo reduce la eficiencia y la calidad del inversor, sino también afecta la vida útil del panel solar y en casos de empresas puede ocasionar sanciones monetarias con el proveedor de energía al contaminar la red eléctrica. Este trabajo se centra en el desarrollo de una nueva topología de inversor para su uso en aplicaciones con paneles solares, en el que la salida del inversor este referida a la misma tierra de la fuente de alimentación, en este caso el PV, eliminando la salida en modo diferencial y de esta manera reduciendo notablemente las corrientes parásitas.""To use the solar energy as electricity is required the use of a photovoltaic panel (PV), which take the benefit of the radiation from solar activity and convert solar energy to electrical energy in the direct current form (DC). To use this technology as a generator of electricity and be able to supply energy into houses, buildings, wells and lighting in remote locations and so on, is necessary to convert this direct current into alternate current (AC). For this point use of DC/AC (also known as inverters) is necessary. Many of the applications of these inverters is when they are used to provide energy to house or buildings, in such cases there are two ways, when they are isolated from the electrical network or when they are connected to it. In cases when they are connected to the electrical network most existing topologies have in its output a differential mode connection, such connection causes that current flow through the parasitic capacitances generated in PV terminals to the neutral point. This current is not desired in PV generating systems since not only reduces the efficiency and quality of the inverter, also affects the service life of the PV, in business might cause monetary sanctions with the provider of the electrical network. This work focuses on the development of a new inverter topology for use in applications with PV, in which its output is referred to the same point of negative power supply, in this case the PV, eliminating the differential mode output and thus significantly reducing the leakage currents.
Modelación matemática de anclado y pre-fusión vesicular en sinapsis
Get PDF"Diferentes estímulo provocan una respuesta en la célula, involucrando muchas veces la secreción de diversas sustancias desde el interior de la célula hacia el medio externo que son captadas posteriormente por otra célula, desarrollando así un sistema de comunicación entre ambas. El proceso de secreción, conocido como exocitosis, es uno de los más importantes dentro de la célula y que involucra una serie de complejos pasos a nivel molecular. Dentro de este proceso se cuenta con la ayuda de un complejo proteico conocido como complejo SNARE, que tiene como principal función anclar y acercar las vesículas que contiene las sustancias a ser secretadas a la membrana plasmática de la célula. Si bien el área de la ciencia encargada de estudiar el fenómeno de la exocitosis ha sido objeto de un extenso estudio desde el punto de vista biológico y químico desde hace más de dos décadas, el proceso de exocitosis en células aún no ha sido descrito en su totalidad. Más aún, se han realizado muy pocos estudios de estos fenómenos desde el punto de vista físico-matemático. En el presente trabajo se propone un modelo de la dinámica de movimiento vesicular en el proceso docking/priming previo a la exocitosis de una vesícula sináptica por medio de leyes clásicas de la física y ecuaciones diferenciales, tomando en cuenta los principales factores físicos que comúnmente se han planteado intervienen en dicho fenómeno.""Several stimulus unleash a reaction on the cell that many times involves the secretion of substances from inside the cell to the outside medium, developing a system of communication between both. This secretion process, known as exocytosis, is one of the most important inside the cell, and it involves a chain of complexes steps at molecular level. This process is helped for a protein complex known as SNARE complex, which has as main function the docking of synaptic vesicles to the plasma membrane and subsequently priming and fusion between both membranes. Even though this area of science has been object of intense studies from the biological and chemical point of view for more of two decades, the process of exocytosis in cells is still not fully understood. Even more, there is almost none study of this phenomena from the physic and mathematical point of view. In this work we propose a dynamical model of the vesicular movement in the docking/priming process that precedes vesicle fusion and neurotransmitter release through classic physic laws and differential equations that takes account of the principal forces and physical factors that has been told in uences this phenomenon.
Robust switched predictive braking control for rollover prevention in wheeled vehicles
Get PDF"The aim of this paper is to propose a differential braking rollover mitigation strategy for wheeled vehicles. The strategy makes use of a polytopic (piecewise linear) description of the vehicle and includes translational and rotational dynamics, as well as suspension effects. The braking controller is robust and the system states are predicted to estimate the rollover risk up to a given time horizon. In contrast to existing works, the switched predictive nature of the control allows it to be applied only when risk of rollover is foreseen, interfering a minimum with driver's actions. The stability of the strategy is analyzed and its robustness is illustrated via numerical simulations using CarSim for a variety of vehicles.
Producción de biohidrógeno a partir de hidrolizados de biomasa lignocelulósica: evaluación en sistemas en lote, semi-continuo y continuo
No full textTesis (Doctorado en Ciencias Ambientales)"El hidrógeno es considerado el combustible del futuro debido a su alto contenido energético (122 kJ/g) y a que el único subproducto de su uso es el agua. Aunado a estas características, la producción de hidrógeno mediante fermentación de residuos orgánicos es carbono neutral. En este sentido, la biomasa lignocelulósica es reconocida como una materia prima potencialmente atractiva para la producción fermentativa de hidrógeno, ya que es abundante y rica en carbohidratos. No obstante, a la fecha, la mayoría de los estudios publicados sobre la producción de hidrógeno a partir de biomasa lignocelulósica han sido llevados a cabo en sistemas por lote, por lo cual, estudios en sistemas semi-continuos y continuos son necesarios para mejorar el entendimiento y futuro desarrollo del proceso. Por lo anterior, esta tesis se enfocó en estudiar el efecto de los hidrolizados lignocelulósicos sobre la producción de hidrógeno en sistemas en lote, semi-continuo y continuo. En el presente estudio, la paja de avena se utilizó como un modelo de biomasa lignocelulósica. Primeramente, se encontró que una hidrólisis secuencial ácida-enzimática es eficaz para solubilizar los azúcares de las fracciones de hemicelulosa y celulosa de la paja de avena. Además, se demostró la factibilidad de producir hidrógeno a partir de los hidrolizados ácidos y enzimáticos en ensayos por lote. Sin embargo, el hidrolizado ácido obtuvo menor rendimiento molar de hidrógeno (RMH) que el hidrolizado enzimático, 1,1 mol H2/mol de azúcar y 2,4 mol de H2/mol de azúcar, respectivamente. El menor RMH del hidrolizado ácido se debió parcialmente a un bajo RMH de la arabinosa, mientras que el mejor rendimiento del hidrolizado enzimático se debió parcialmente a la fermentación de la preparación comercial enzimática (Celluclast 1.5L), lo cual contribuyó a la producción de hidrógeno. Posteriormente, se demostró la viabilidad de producir hidrógeno a partir de ambos hidrolizados en un reactor anaerobio en lote secuencial (ASBR). No obstante, se observó que la alimentación inicial con sustratos modelo (glucosa/xilosa) facilitó la obtención de valores altos de RMH (2 mol H2/mol azúcar) y de velocidad de producción de hidrógeno (VPH, 278 ml H2/L-h); mientras que la sustitución gradual de estos sustratos modelo por hidrolizados, llevó a la obtención de valores de RMH y VPH menores, 0,8 mol H2/mol azúcar y 29,6 ml H2/L-h, respectivamente.""Hydrogen is considered as the fuel of the future because of its high energy content (122 kJ/g) and because water is the only byproduct of its use. Moreover, the production of hydrogen via fermentation of organic wastes is carbon neutral. In this regard, lignocellulosic biomass has been recognized as a potentially attractive feedstock for the fermentative hydrogen production, since it is abundant and rich in carbohydrates. However, up to now, most of the reported studies on hydrogen production from lignocellulosic biomass have been carried out on batch mode; therefore, studies on semi-continuous and continuous systems are required in order to improve the understanding and further development of the process. This thesis studied the effect of lignocellulosic biomass hydrolysates over the hydrogen production on batch, semi-continuous and continuous systems. Oat straw was used as a lignocellulosic biomass model. Firstly, it was found that a sequential acid-enzymatic hydrolysis resulted effective to solubilize sugars from the hemicellulose and cellulose fractions of the oat straw. Then, the feasibility to produce hydrogen from acid and enzymatic oat straw hydrolysates was demonstrated in batch assays. Nonetheless, lower hydrogen molar yield (HMY) was obtained with the acid hydrolysate (1.1 mol H2/mol reducing sugars) as compared to the enzymatic hydrolysate (2.4 mol H2/mol reducing sugars). Lower performance of the acid hydrolysate was found partially due to a lower HMY from arabinose, whereas the better performance of the enzymatic hydrolysate was found partially due to fermentation of the commercial enzymatic preparation (Celluclast 1.5L), which contributed to the hydrogen production. Afterwards, the feasibility to produce hydrogen from both hydrolysates was also demonstrated in an anaerobic sequencing batch reactor (ASBR). However, it was observed that the initial feeding with model substrates (glucose/xylose) promoted high HMY (2 mol H2/mol sugar consumed) and high hydrogen production rate (HPR, 278 mL H2/L-h); whereas the gradual substitution of the model substrates by hydrolysates led to lower HMY and HPR, 0.8 mol H2/mol sugar consumed and 29.6 mL H2/L-h, respectively. Furthermore, PCR-DGGE analysis showed that Clostridium pasteurianum (99% of similarity) was the most abundant specie when model substrates were fed and that microbial population became more diverse when hydrolysates were fed.
An unusual syn-eruptive bimodal eruption: The Holocene Cuicuiltic Member at Los Humeros caldera, Mexico
Get PDF"The Cuicuiltic Member (CM) at Los Humeros Caldera, eastern Mexican Volcanic Belt is a Holocene (6.4 ka B.P.) succession of alternated fallout deposits of contrasting composition (trachydacite pumice and basaltic andesite scoria). The CM covers approximately 250 km(2) on its proximal fades and its thickness ranges from 1.5 m to 8.0 m. It postdates two caldera-forming ignimbrites (Xaltipan and Zaragoza) and numerous Plinian successions. It is subdivided in 9 units (C1 to C9) according to its textural and chemical characteristics. Sub-horizontal, topography-draping layers of trachydacite pumice lapilli, andesitic pumice lapilli and basaltic-andesite scoria lapilli with sporadic one-meter blocks are common lithofacies. The base is formed by coarse trachydacite pumice lapilli (C1 and C2), overlain by a layer with banded pumice (C3). Thin layers of ash and ash-tuff are intermittent on lower units, whilst continuous at the base of C4. The middle units, C4 and C6 are basaltic-andesite pumice, and scoria lapilli to blocks; C5 is in-between the two mafic units and it is represented by a layer of pale grey pumice lapilli. Units C7 and C8 are a mixture of white trachydacite pumice, scoria lapilli and banded pumice. The uppermost layer, C9, is a brown to grey andesitic pumice lapilli. Extensive fieldwork allowed a close and reliable correlation of layers that helps to understand the complexity of stratigraphic relations and sources for those layers. The distribution of these units is varied across the caldera, with the trachydacite layers dispersal from the centre towards the NW, whilst the andesitic units have maximum thicknesses over the SE and NE sectors of the caldera. Isopach and isopleth maps, combined with detailed mapping of near-vent spatter facies, orientation of local bomb sags and variation of mean clasts size for some layers were very useful to determine the vent location, particularly for the andesitic-basaltic layers.
A different three-port DC/DC converter for standalone PV system
Get PDF"A three-port converter suitable for standalone applications is proposed in this paper. Each port is used for specific input or output, and its functions depend on the port; they are the renewable source, the battery set, and the output port. This proposed converter is considered for standalone operation, but it is not limited to it. Not only the system is able to deliver energy independently from each input source or in a mixed way for the output, but also the battery system may be charged from the renewable source just in case it is required. The battery port is only used when it is required; this allows increasing battery lifetime. Another important feature is that, in case of a renewable source failure, the energy is automatically demanded from the battery set, like an uninterruptible power supply. The system is able to track the maximum power of the renewable source when it is required. Operation, analysis, simulation, and experimental results are described in detail.
A dehydrin-dehydrin interaction: the case of SK3 from Opuntia streptacantha
Get PDF"Dehydrins belongs to a large group of highly hydrophilic proteins known as Late Embryogenesis Abundant (LEA) proteins. It is well known that dehydrins are intrinsically disordered plant proteins that accumulate during the late stages of embryogenesis and in response to abiotic stresses; however, the molecular mechanisms by which their functions are carried out are still unclear. We have previously reported that transgenic Arabidopsis plants overexpressing an Opuntia streptacantha SK3 dehydrin (OpsDHN1) show enhanced tolerance to freezing stress. Herein, we show using a split-ubiquitin yeast two-hybrid system that OpsDHN1 dimerizes. We found that the deletion of regions containing K-segments and the histidine-rich region in the OpsDHN1 protein affects dimer formation. Not surprisingly, in silico protein sequence analysis suggests that OpsDHN1 is an intrinsically disordered protein, an observation that was confirmed by circular dichroism and gel filtration of the recombinantly expressed protein. The addition of zinc triggered the association of recombinantly expressed OpsDHN1 protein, likely through its histidine-rich motif. These data brings new insights about the molecular mechanism of the OpsDHN1 SK3-dehydrin.
Expresión, purificación y caracterización de la enzima CGI58/ABHD5
Get PDFTesis (Maestría en Ciencias en Biología Molecular)"CGI58/ABHD5 es una enzima que participa en el metabolismo de lipidos como activador de la triglicerido lipasa del tejido adiposo(ATGL). Recientemente se ha descrito que CGI58 tiene actividador de lisofosfatidil aciltrasferasa, por lo que se le ha relacionado con procesos de señalizacion en la produccion de lipidos eicosanoides. A pesar de que CGI58 ha sido objeto de numerosos trabajos de investigacion, a la fecha sus estructura tridimensional no ha sido determinada. El objetivo central de este trabajo fue obtener una construccion de CGI58 que se exprese de forma soluble y a una concentracion adecuada para iniciar experimentos de cristalizacion asi resolver su estructura tridimensional por difracción de rayos X. Aqui reportamos el modelo por homologia de CGI58 de humano realizado con I-TASER, el cual se úso para diseñar una construccion deletada de 50 residuos en el extremo N-Terminal. Se generaron seis construcciónes de CGI58, dos con la secuencuia de ráton y cuatro con la de humano, que codifican para la enzima silvestre y una deletada. Cuatro de las seis construcciónes han sido expresadas como proteinas recombinantes en E.coli, la purificación de las mismas ha sido estandarizada utilizando cromatografia de afinidad a niquel. Hemos determinado que el detergente octil glucosido, permite aumentar la concentración de proteina soluble aproximadamente diez veces. Finalmente, observamos que el uso de glicerol al 10%.magnesio 2mM y pH 7.5 tienen un impacto positivo en CGI58. Sin embargo, queda pendiente evaluar el uso de estos aditivos en el proceso de purificación.""CGI58/ABHD5 is an enzyme that participates in the lipid metabolism as an activator of adipose triglyceride lipase (ATGL). Recently it has been reported that CGI58 has a lysophosphatidyl acyltransferase activity, so it has been associated with the “signaling processes” in the production of eicosanoid lipids. Although CGI58 has been the subject of several studies, the three-dimensional structure has not yet been determined. The main goal of this work was to generate a construct that expresses CGI58 in a soluble form and at suitable concentration to initiate crystallization experiments; this will allow us to solve its structure by X-ray crystallography in the near future. Here, we report a homology model of human CGI58 performed with I-TASSER, which was used to design a truncated protein of 50 residues at the N-terminus. Two constructs of mouse CGI58 were generated,comprising the wild type and the truncated enzymes. Two optimized DNA sequences for the human CGI58 were designed, for each one we have the corresponding construct that express the wild type and the truncated enzyme. So, six protein constructs were generated in this work. Four of the six constructs have been expressed as recombinant proteins in E. coli; all of them have been purified by nickel affinity chromatography. We found that the detergent octyl glucoside increases the soluble protein concentration about ten fold. Finally, we observed that the use of 10% glycerol, 2 mM magnesium and pH 7.5 had a positive impact on CGI58 thermal stability. However, the evaluation of these additives in the purification step has not been tested yet.