5,448 research outputs found
Reporte de las serpientes del municipio de Tamalameque, Cesar - Colombia
Objetivo. Identificar preliminarmente los ofidios del municipio de Tamalameque, departamento del Cesar-Colombia. Materiales y métodos. Entre enero y mayo de 2009, mediante búsqueda libre y captura manual se efectuaron muestreos de serpientes, con dos muestreos por mes y un esfuerzo de captura de cuatro horas/hombres. Resultados. Se reporta para esta localidad la presencia de tres familias de serpientes, distribuidas en 12 géneros y 13 especies; La familia Colubridae fue la mejor representada con el 76.93% de las especies reportadas, seguida de la familia Boidae 15.38% y Anomalepidae 7.69%. Conclusiones. Los resultados permiten deducir que la familia Colúbridae es un componente herpetológico importante para la Ciénaga del Cristo y que las amenazas antropicas para los ofidios en esta localidad son la destrucción de hábitat y falta de conocimiento ecológico y etológico por parte de los pobladore
Influence of Embankments with Parapets on the Cross-Wind Turbulence Intensity at the Contact Wire of Railway Overheads
Winds as an environmental factor can cause significant difficulties for the railway system operation. The railway overhead has been particularly vulnerable to cross-winds related problems, such as development of undamped oscillations due to galloping phenomenon. The installation of windbreaks to decrease the aerodynamic loads on the train can affect the loads on railway overheads triggering cable galloping. One essential parameter to indicate the influence of the parapet wake on the catenary contact wire is the turbulence intensity. In this paper the results of an experimental analysis of the turbulence intensity due to the presence of parapets carried out in a wind tunnel are reported. Embankments equipped with different parapets have been tested and turbulence intensity has been measured at both contact wire locations, windward and leeward. The relative influence of the parapets is measured through a reduced turbulence intensity, defined as the ratio between the turbulence intensity measured with parapet and the turbulence intensity in the case without any parapet on the embankment. In general the reduced turbulence intensity increases as the height of the parapet increases
Geometric constraint subsets and subgraphs in the analysis of assemblies and mechanisms
Geometric Reasoning ability is central to many applications in CAD/CAM/CAPP environments. An increasing demand exists for Geometric Reasoning systems which evaluate the feasibility of virtual scenes specified by geometric relations. Thus, the Geometric Constraint Satisfaction or Scene Feasibility (GCS/SF) problem consists of a basic scenario containing geometric entities, whose context is used to propose constraining relations among still undefined entities. If the constraint specification is consistent, the answer of the problem is one of finitely or infinitely many solution scenarios satisfying the prescribed constraints. Otherwise, a diagnostic of inconsistency is expected. The three main approaches used for this problem are numerical, procedural or operational and mathematical. Numerical and procedural approaches answer only part of the problem, and are not complete in the sense that a failure to provide an answer does not preclude the existence of one. The mathematical approach previously presented by the authors describes the problem using a set of polynomial equations. The common roots to this set of polynomials characterizes the solution space for such a problem. That work presents the use of Groebner basis techniques for verifying the consistency of the constraints. It also integrates subgroups of the Special Euclidean Group of Displacements SE(3) in the problem formulation to exploit the structure implied by geometric relations. Although theoretically sound, these techniques require large amounts of computing resources. This work proposes Divide-and-Conquer techniques applied to local GCS/SF subproblems to identify strongly constrained clusters of geometric entities. The identification and preprocessing of these clusters generally reduces the effort required in solving the overall problem. Cluster identification can be related to identifying short cycles in the Spatial Constraint graph for the GCS/SF problem. Their preprocessing uses the aforementioned Algebraic Geometry and Group theoretical techniques on the local GCS/SF problems that correspond to these cycles. Besides improving the efficiency of the solution approach, the Divide-and-Conquer techniques capture the physical essence of the problem. This is illustrated by applying the discussed techniques to the analysis of the degrees of freedom of mechanisms.MSC: 68U07La habilidad del Razonamiento Geométrico es central a muchas aplicaciones de CAD/CAM/CAPP (Computer Aided Design, Manufacturing and Process Planning). Existe una demanda creciente de sistemas de Razonamiento Geométrico que evalúen la factibilidad de escenas virtuales, especificados por relaciones geométricas. Por lo tanto, el problema de Satisfacción de Restricciones Geométricas o de Factibilidad de Escena (GCS/SF) consta de un escenario básico conteniendo entidades geométricas, cuyo contexto es usado para proponer relaciones de restricción entre entidades aún indefinidas. Si la especificación de las restricciones es consistente, la respuesta al problema es uno del finito o infinito número de escenarios solución que satisfacen las restricciones propuestas. De otra forma, un diagnóstico de inconsistencia es esperado. Las tres principales estrategias usadas para este problema son: numérica, procedimental y matemática. Las soluciones numérica y procedimental resuelven solo parte del problema, y no son completas en el sentido de que una ausencia de respuesta no significa la ausencia de ella. La aproximación matemática previamente presentada por los autores describe el problema usando una serie de ecuaciones polinómicas. Las raíces comunes a este conjunto de polinomios caracterizan el espacio solución para el problema. Ese trabajo presenta el uso de técnicas con Bases de Groebner para verificar la consistencia de las restricciones. Ella también integra los subgrupos del grupo especial Euclídeo de desplazamientos SE(3) en la formulación del problema para explotar la estructura implicada por las relaciones geométricas. Aunque teóricamente sólidas, estas técnicas requieren grandes cantidades de recursos computacionales. Este trabajo propone técnicas de Dividir y Conquistar aplicadas a subproblemas GCS/SF locales para identificar conjuntos de entidades geométricas fuertemente restringidas entre sí. La identificación y pre-procesamiento de dichos conjuntos locales, generalmente reduce el esfuerzo requerido para resolver el problema completo. La identificación de dichos sub-problemas locales está relacionada con la identificación de ciclos cortos en el grafo de Restricciones Geométricas del problema GCS/SF. Su preprocesamiento usa las ya mencionadas técnicas de Geometría Algebraica y Grupos en los problemas locales que corresponden a dichos ciclos. Además de mejorar la eficiencia de la solución, las técnicas de Dividir y Conquistar capturan la esencia física del problema. Esto es ilustrado por medio de su aplicación al análisis de grados de libertad de mecanismos.MSC: 68U0
Design of a bench to allocate accelerometers and gyroscopes on a sailplane
El proyecto consiste en el diseño de unos soportes destinados a llevar acelerómetros y giroscopo en un planeador, con el objeto de poder realizar medidas relacionadas con su movimiento
Doctor of Philosophy
dissertationA common pattern in systems designed to transport liquids and gases, such as the vascular and respiratory systems, is the use of branched tubular structures to create a network that interconnects the entire body. The cellular cues required for generating these complex networks are not well understood. To identify components involved in generating branched tubular networks we are studying the Drosophila melanogaster tracheal (respiratory) system. The Drosophila larval tracheal system is composed of approximately 10,000 interconnected tubes which serve to transport oxygen and other gases throughout the body. The branching and tubulogenesis (the formation of an open space or lumen that extends throughout the length of a branch to make it a tube) seen during Drosophila tracheal system development may parallel similar processes seen in other organisms. The molecular and genetic tools available for Drosophila provide us an excellent opportunity to identify factors required in branching and lumen formation. A forward genetic screen of the X chromosome was conducted to isolate lethal mutations affecting branching and lumen formation in tracheal terminal cells of Drosophila. Tracheal terminal cells are specialized cells that undergo subcellular branching and tubulogenesis, and are responsible for transporting gases and exchanging gases in hypoxic tissues. Thirty-two lines with mutations affecting different aspects of branching and lumen formation were identified. Of these 32 we focused on five iv lines in which tracheal terminal cells undergo essentially normal branching, but are unable to generate a functional lumen. These mutants have been mapped to discrete genetic intervals using a recombination mapping strategy. The mapping has been further refined for two of these five lines by using a combination of single nucleotide polymorphisms (SNP) and P-element recombination frequencies allowing us to identify a small number of candidate genes for each of these mutations. Additionally, for one of these mutants we have identified the causative gene as Zpr1 (Zinc-finger protein 1), an evolutionarily conserved protein characterized by two C4 zinc fingers and two conserved homology domains
Multigene Metabolic Engineering Via The Chloroplast Genome
The vast majority of valuable agronomic traits are encoded polygenetically. Chloroplast genetic engineering offers an alternate approach to multigene engineering by allowing the insertion of entire pathways in a single transformation event, while being an environmentally friendly approach. Stable integration into the chloroplast genome and transcription of the phaA gene coding for β-ketothiolase was confirmed by Southern and northern blots. Coomassie-stained gel and western blots confirmed hyperexpression of β-ketothiolase in leaves and anthers, with high enzyme activity. The transgenic lines were normal except for the male sterile phenotype, lacking pollen. Scanning electron microscopy revealed a collapsed morphology of the pollen grains. Transgenic lines followed an accelerated anther developmental pattern, affecting their development and maturation, resulting in aberrant tissue patterns. Abnormal thickening of the outer wall, enlarged endothecium and vacuolation, decreased the inner space of the locules, affecting pollen grain and resulted in the irregular shape and collapsed phenotype. Reversibility of the male sterility phenotype was achieved by exposing the plants to continuous illumination, producing viable pollen and copious amounts of seeds. This is the first report of engineered cytoplasmic male sterility and offers a new tool for transgene containment for both nuclear and organelle genomes. Detailed characterization of transcriptional, posttranscriptional and translational processes of heterologous operons expressed via the chloroplast genome is reported here. Northern blot analyses performed on chloroplast transgenic lines harboring seven different heterologous operons, revealed that in most cases, only polycistronic mRNA was produced or polycistrons were the most abundant form and that they were not processed into monocistrons. Despite such lack of processing, abundant foreign protein accumulation was detected in these transgenic lines. Interestingly, a stable secondary structure formed from a heterologous bacterial intergenic sequence was recognized and efficiently processed, indicating that the chloroplast posttranscriptional machinery can indeed recognize sequences that are not of chloroplast origin, retaining its prokaryotic ancestral features. Processed and unprocessed heterologous polycistrons were quite stable even in the absence of 3\u27UTRs and were efficiently translated. Unlike native 5\u27UTRs, heterologous secondary structures or 5\u27UTRs showed efficient translational enhancement independent of any cellular control. Finally, we observed abundant read-through transcription in the presence of chloroplast 3\u27UTRs. Such read-through transcripts were efficiently processed at introns present within native operons. Addressing questions about polycistrons, as well as the sequences required for their processing and transcript stability are essential for future approaches in metabolic engineering. Finally, we have shown phytoremediation of mercury by engineering the mer operon via the chloroplast genome under the regulation of chloroplast native and heterologous 5\u27UTRs. These transgenenic plants hyperexpress were able to translate MerA and MerB enzymes to levels detectable by coomassie stained gel. The knowledge acquired from these studies offer guidelines for engineering multigene pathways via the chloroplast genome
On the use of preference-based evolutionary multi-objective optimization for solving a credibilistic portfolio selection model
The portfolio selection problem tries to identify the assets to allocate the capital, and the proportion to be devoted to each asset, for maximizing the returns at the minimum risk. By nature, this is a multi-objective optimization problem. In this work, we propose a three-objective model for portfolio selection, in which the uncertainty of the portfolio returns is modelled by means of LR-power fuzzy variables. We consider as criteria the credibilistic expected return (to be maxi-
mized), the below-mean absolute semi-deviation as a risk measure (to be minimized), and a loss function which evaluates the credibility of achieving a non-positive return (to be minimized). The uncorrelation among the risk and loss measures concludes that they provide different information.
Budget, cardinality, and diversification constraints are considered. To generate non-dominated portfolios fitting the investor' expectations, preference-based evolutionary algorithms are applied. The preferences are given by aspiration values to be attained by the objectives and profiles representing aggressive, cautious, and conservative investors are analysed. The results for data of the IBEX35 show that portfolios improving the preferences are found in the cautious and aggressive cases, while portfolios with objective values as close as possible to the expectations are obtained in the conservative case. In the generation process, the credibilistic loss has played an important role to and diversified portfolios.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
First report of Leptosphaeria biglobosa ‘brassicae’ as causal agent of phoma leaf spot in Brassica napus (Canola) in Argentina
Canola(Brassicanapus L.) is the second largest oilseed crop in the worldproviding 13% of the world´s oil supply. This crop has been grown in Argentinasince the 1930s, and the area devoted to its cultivation varies every year,reaching a maximum of 95000 Ha in the 2012/2013 growing season. Because of theoccurrence of optimal weather conditions and soils with high fertility, theaverage yield in this region is about 2000 kg/Ha. Phoma leaf spot and Phomastem canker are considered the most important and devastating diseases in Brassica napus andother Brassicaespecies [1]. In both cases, the causal agent is a complexof two closely related fungal species, Leptosphaeria maculans and L. biglobosa. In Argentina,the presence of L. maculans incanola plants was reported for the first time in 2004 [2], but the existence ofL.biglobosa has not been recorded so far. During the 2015/2016season, we collected several samples with typical Phoma leaf spot symptoms fromcanola plants growing in fields from the north and northeastern regions of the Buenos Aires province.The necrotic lesions were circular to irregularly oval, 8 to 15 mm in diameter,pale brown in the center, grayish green at the margin and characterized withthe presence of pycnidia. Several leaf pieces with lesions were rinsed twicewith deionized sterile water and placed in a humid chamber (90 mm diameterPetri dish with a layer of filter paper soaked in deionized sterile water) during2-3 days to induce the pycnidia to exude cirri of conidia. After this period,one cirrus per sample was transferred onto PDA plates supplemented withantibiotics (15 mg/L streptomycin, 15 mg/L gentamicin and 12 mg/L tetracycline)using an inoculation needle under stereoscopic microscope. Thus, severalisolates were obtained, some of them showing rapid mycelial growth rate andpigment production on PDA medium, as showed by the isolate Tapidor of L. biglobosa thatwe used as control (kindly provided by Professor Bruce Fitt, University ofHertfordshire-UK). In order to confirm the identity of these isolates, a PCRassay using genomic DNA as template was performed to distinguish L. maculans from L. biglobosa withthe species-specific primers LmacR, LmacF,and LbigF ina three-primers strategy described by Gaetan (2005)[3]. These reactions gave a444-bp amplicon as expected for L. biglobosa ´brassicae´.In addition, these results were confirmed by sequencing the nuclear ribosomalinternal transcribed spacer (ITS) region, which showed a 99% of identity withthe sequence of L. biglobosa ´brassicae´at the GenBank database (FO905468). L. biglobosa isolateswere then tested for pathogenicity on the canola cultivars Westar and Bioaureo2286 (Nuseed). With this purpose, cotyledons of 10-day-old seedlings werepricked with a needle, and each wound inoculated with 10 μl ofa conidial suspension (107 42conidia/ml). Sterilized distilled water was used as control. Developing primaryleaves were removed every 2-3 days in order to ensure that cotyledons continueto expand. Fourteen days after inoculation, irregular and brown necroticlesions were visible at the site of inoculation. These cotyledons were detachedand placed in a humid chamber to induce pycnidia formation. After three dayscirri of conidia were transferred to a plate with PDA supplemented with antibioticsas mentioned above. The identity of these isolates of L. biglobosa wereconfirmed by pigment production on PDA medium and by PCR assay usingspecies-specific primers. To our knowledge, this is the first report of L. biglobosa ´brassicae´as a pathogen of canola in Argentina. This finding shows that in Argentina´scanola cropping areas not 50 only L. maculans but alsoL.biglobosa are the causal agents of Phoma leaf spot disease.Fil: Rossi, Franco Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Romero, Fernando Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Garriz, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Ruiz, Oscar Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentin
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