Molecular cloning and expression studies of two divergent α-tubulin genes in Neurospora crassa

Three α-tubulin isoforms were previously detected in Neurospora crassa. We have cloned and analysed two α-tubulin cDNAs, Tub αA and Tub αB that encode polypeptides of 453 and 451 amino acids, respectively. The encoded amino acids exhibit an unusual divergence of 35%. This is the highest divergence ever observed between α-tubulins from the same species. The expression of the two genes is developmentally regulated. We did not detect any transcription of the Tub αA gene in dormant macroconidia and during the first 30 min of development even though the α-tub A protein is already present in the early stage of germination. In contrast, the Tub αB gene is continuously transcribed during the vegetative cycle and the expression profile of the protein follows the ones of its mRN

PID passivity-based droop control of power converters:Large-signal stability, robustness and performance

We present a full review of PID passivity-based controllers (PBC) applied to power electronic converters, discussing limitations, unprecedented merits and potential improvements in terms of large-signal stability, robustness and performance. We provide four main contributions. The nominal case is first considered and it is shown—under the assumption of perfect knowledge of the system parameters—that the PID-PBC is able to guarantee global exponential stability of a desired operating point for any positive gains. Second, we analyze robustness of the controller to parameters uncertainty for a specific class of power converters, by establishing precise stability margins. Third, we propose a modification of the controller by introducing a leakage, in order to overcome some of the intrinsic performance and robustness limitations. Interestingly, such controller can be interpreted at steady-state as a droop between the input and the passive output, similar to traditional primary controllers. Fourth, we robustify the design against saturation of the control input via an appropriate monotone transformation of the controller. The obtained results are thoroughly discussed and validated by simulations on two relevant power applications: a DC/DC boost converter and an HVDC grid-connected voltage source converter

A short-turning policy for the management of demand disruptions in rapid transit systems

Rapid transit systems timetables are commonly designed to accommodate passenger demand in sections with the highest passenger load. However, disruptions frequently arise due to an increase in the demand, infrastructure incidences or as a consequence of fleet size reductions. All these circumstances give rise to unsupplied demand at certain stations, which generates passenger overloads in the available vehicles. The design of strategies that guarantee reasonable user waiting time with small increases of operation costs is now an important research topic. This paper proposes a tactical approach to determine optimal policies for dealing with such situations. Concretely, a short-turning strategy is analysed, where some vehicles perform short cycles in order to increase the frequency among certain stations of the lines and to equilibrate the train occupancy level. Turn-back points should be located and service offset should be determined with the objective of diminishing the passenger waiting time while preserving certain level of quality of service. Computational results and analysis for a real case study are provided.Junta de Andalucía P09-TEP-5022Natural Sciences and Engineering Research Council of Canada (NSERC) 39682-1

Analyzing the theoretical capacity of railway networks with a radial-backbone topology

In this work we propose a mechanism to optimize the capacity of the main corridor within a railway network with a radial-backbone or X-tree structure. The radial-backbone (or Xtree) structure is composed of two types of lines: the primary lines that travel exclusively on the common backbone (main corridor) and radial lines which, starting from the common backbone, branch out to individual locations. We define possible line configurations as binary strings and propose operators on them for their analysis, yielding an effective algorithm for generating an optimal design and train frequencies. We test our algorithm on real data for the high speed line Madrid-Seville. A frequency plan consistent with the optimal capacity is then proposed in order to eliminate the number of transfers between lines as well as to minimize the network fleet size, determining the minimum number of vehicles needed to serve all travel demand at maximum occupancy.Ministerio de Economía y Competitividad MTM2012-37048Junta de Andalucía P09-TEP-5022Junta de Andalucía P10-FQM-5849Canadian Natural Sciences and Engineering Research Council 39682-1

Maximizing Trip Coverage in the Location of a Single Rapid Transit Alignment

This article describes several heuristics for the construction of a rapid transit alignment. The objective is the maximization of the total origin-destination demand covered by the alignment. Computational results show that the best results are provided by a simple greedy extension heuristic. This conclusion is confirmed on the Sevilla data for scenarios when the upper bound for inter-station distance is greater than 1250 m. Otherwise, when those upper bounds are smaller (750mand 1000 m), an insertion heuristic followed by a post-optimization phase yields the best results. Computational times are always insignificant.Canadian Natural Sciences and Engineering Research Council OGP0039682Ministerio de Ciencia y Tecnología BFM2000-1052-C02-01Ministerio de Ciencia y Tecnología BFM2003-04062/MAT

An Integrated Methodology for the Rapid Transit Network Design

The Rapid Transit System Network Design Problem consists of two intertwined location problems: the determination of alignments and that of the stations. The underlying space, a network or a region of the plane, mainly depends on the place in which the system is being constructed, at grade or elevated, or underground, respectively. For solving the problem some relevant criteria, among them cost and future utilisation, are applied. Urban planners and engineering consulting usually select a small number of corridors to be combined and then analysed. The way of selecting and comparing these alternatives is performed by the application of the four-stage transit planning model. Due to the complexity of the overall problem, during last ten years some efforts have been dedicated to modelling some aspects as optimisation problems and to provide Operations Research methods for solving them. This approach leads to the consideration of a higher number of candidates than that of the classic corridor analysis. The main aim of this paper is to integrate the steps of the transit planning model (trip attraction and generation, trip distribution, mode choice and traffic equilibrium) into an optimisation process.Ministerio de Ciencia y Tecnología BFM2003-04062/MATEMinisterio de Fomento 2003/136

Purification of a 47-kDa calmodulin-binding polypeptide as an actin-binding protein from Neurospora crassa

We have enriched a 47-kDa polypeptide (p47) from Neurospora crassa on the basis of its affinity to calmodulin. The p47 was purified to homogeneity by chromatography on a Mono S cation exchange column and evidence is presented that the polypeptide co-sediments specifically with F-actin. The intracellular distribution of p47 and actin was also examined using indirect double immunofluorescence staining of cells at different stages of development. Our results suggest that by altering the conformation binding site of actin to p47, calmodulin could play a regulatory role in the polarized hyphal growth of N. crass

Planning Rapid Transit Networks

Rapid transit construction projects are major endeavours that require long-term planning by several players, including politicians, urban planners, engineers, management consultants, and citizen groups. Traditionally, operations research methods have not played a major role at the planning level but several tools developed in recent years can assist the decision process and help produce tentative network designs that can be submitted to the planners for further evaluation. This article reviews some indices for the quality of a rapid transit network, as well as mathematical models and heuristics that can be used to design networks.Canadian Natural Sciences and Engineering Research Council 39682-10Ministerio de Ciencia e Innovación MTM 2009-14243Junta de Andalucía P09-TEP-502

La comunidad de ostrácodos en humedales del sudeste de la Península Ibérica

Se muestran los primeros datos sobre la comunidad de ostrácodos en los humedales del sudeste de España (provincias de Jaén y Córdoba). Se han estudiado un total de 21 humedales, habiéndose registrado la presencia de 12 especies de ostrácodos, pertenecientes a 8 géneros diferentes. Los valores de singularidad muestran la importancia de los humedales temporales y salinos para esta comunidad biótica. Esta aportación pone en valor la necesidad de incrementar el conocimiento que se tiene sobre la distribución y ecología de las especies de ostrácodos en la Península Ibéric