862 research outputs found
Parametric studies of stitching effectiveness for preventing substructure disbond
A methodology is desired that will allow a designer to select appropriate amounts of through-thickness reinforcement needed to meet design requirements. The goal is to use a relatively simple analysis to minimize the amount of testing that needs to be performed, and to make test results from simple configurations applicable to more general structures. Using this methodology one should be able to optimize the selection of stitching materials, the weight of the yarn, and the stitching density. The analysis approach is to treat substructure disbond as a crack propagation problem. In this approach, the stitches have little influence until a delamination begins to grow. Once the delamination reaches, or extends beyond a stitch, the stitch serves to reduce the strain-energy-release-rate (G) at the crack tip for a given applied load. The reduced G can then be compared to the unstitched materials toughness to predict the load required to further extend the crack. The current model treats the stitch as a simple spring which responds to displacements in the vertical (through-thickness) direction. In concept, this approach is similar to that proposed by other authors. Test results indicate that the model should be refined to include the shearing stiffness of the stitch. The strain-energy-release-rate calculations are performed using a code which uses interconnected higher-order plates to model built-up composite cross-sections. When plates are stacked vertically, the interfacial tractions between the plates can be computed. The plate differential equations are solved in closed-form. The code, called SUBLAM, was developed as part of this section in one dimension. Because of this limitation, rows of stitches are treated as a two-dimensional sheet. The spring stiffness of a row of stitches can be estimated from the stitch material, weight, and density. As a practical and conservative approach, we can assume that the stitch is bonded until a crack passes the stitch location. After the crack passes, it is fully bonded. A series of tests were performed to exercise this methodology and incorporated an attached flange such that the sudden change in thickness initiated a delamination. The analysis was used to estimate the materials' critical G from that of the unstitched specimens. With this data, a prediction was made for the load required to delaminate the stitched specimens. Using the methodology, design charts have been created for simplified geometries. These charts give stitch force, along with G(sub 1) and G(sub 2) as as function of the stitch spring stiffness. Using the charts, it should be possible to determine the stitch spring stiffness and strength required to reduce the G to a desired level. From these parameters, the actual stitching material, weight, and density can be computed
A grid and cloud-based framework for high throughput bioinformatics
Recent advances in genome sequencing technologies have unleashed a flood of new data. As a result, the computational analysis of bioinformatics data sets has been rapidly moving from a labbased desktop computer environment to exhaustive analyses performed by large dedicated computing resources. Traditionally, large computational problems have been performed on dedicated clusters of high performance machines that are typically local to, and owned by, a particular institution. The current trend in Grid computing has seen institutions pooling their computational resources in order to offload excess computational work to remote locations during busy periods. In the last year or so, commercial Cloud computing initiatives have matured enough to offer a viable remote source of reliable computational power. Collections of idle desktop computers have also been used as a source of computational power in the form of âvolunteer Gridsâ. The field of bioinformatics is highly dynamic, with new or updated versions of software tools and databases continually being developed. Several different tools and datasets must often be combined into a coherent, automated workflow or pipeline. While existing solutions are available for constructing workflows, there is a clear need for long-lived analyses consisting of many interconnected steps to be able to migrate among Grid and cloud computational resources dynamically. This project involved research into the principles underlying the design and architecture of flexible, high-throughput bioinformatics processes. Following extensive research into requirements gathering, a novel Grid-based platform, Microbase, has been implemented that is based on service-oriented architectures and peer-to-peer data transfer technology. This platform has been shown to be amenable to utilising a wide range of hardware from commodity desktop computers, to high-performance cloud infrastructure. The system has been shown to drastically reduce the bandwidth requirements of bioinformatics data distribution, and therefore reduces both the financial and computational costs associated with cloud computing. The system is inherently modular in nature, comprising a service based notification system, a data storage system scheduler and a job manager. In keeping with e-Science principles, each module can operate in physical isolation from each other, distributed within an intranet or Internet. Moreover, since each module is loosely coupled via Web services, modules have the potential to be used in combination with external service oriented components or in isolation as part of another system. In order to demonstrate the utility of such an open source system to the bioinformatics community, a pipeline of inter-connected bioinformatics applications was developed using the Microbase system to form a high throughput application for the comparative and visual analysis of microbial genomes. This application, Automated Genome Analyser (AGA) has been developed to operate without user interaction. AGA exposes its results via Web-services which can be used by further analytical stages within Microbase, by external computational resources via a Web service interface or which can be queried by users via an interactive genome browser. In addition to providing the necessary infrastructure for scalable Grid applications, a modular development framework has been provided, which simplifies the process of writing Grid applications. Microbase has been adopted by a number of projects ranging from comparative genomics to synthetic biology simulations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
DipyrrinatoâIridium(III) Complexes for Application in Photodynamic Therapy and Antimicrobial Photodynamic Inactivation
The generation of bio-targetable photosensitizers is of utmost importance to the emerging field of photodynamic therapy and antimicrobial (photo-)therapy. A synthetic strategy is presented in which chelating dipyrrin moieties are used to enhance the known photoactivity of iridium(III) metal complexes. Formed complexes can thus be functionalized in a facile manner with a range of targeting groups at their chemically active reaction sites. Dipyrrins with N- and O-substituents afforded (dipy)iridium(III) complexes via complexation with the respective Cp*-iridium(III) and ppy-iridium(III) precursors (dipy=dipyrrinato, Cp*=pentamethyl-eta(5)-cyclopentadienyl, ppy=2-phenylpyridyl). Similarly, electron-deficient [Ir-III(dipy)(ppy)(2)] complexes could be used for post-functionalization, forming alkenyl, alkynyl and glyco-appended iridium(III) complexes. The phototoxic activity of these complexes has been assessed in cellular and bacterial assays with and without light; the [Ir-III(Cl)(Cp*)(dipy)] complexes and the glyco-substituted iridium(III) complexes showing particular promise as photomedicine candidates. Representative crystal structures of the complexes are also presented
Stable, Time-Dependent, Exact Solutions for Brane Models with a Bulk Scalar Field
We derive two classes of brane-world solutions arising in the presence of a
bulk scalar field. For static field configurations, we adopt a time-dependent,
factorizable metric ansatz that allows for radion stabilization. The solutions
are characterized by a non-trivial warping along the extra dimension, even in
the case of a vanishing bulk cosmological constant, and lead to a variety of
inflationary, time-dependent solutions of the 3D scale factor on the brane. We
also derive the constraints necessary for the stability of these solutions
under time-dependent perturbations of the radion field, and we demonstrate the
existence of phenomenologically interesting, stable solutions with a positive
cosmological constant on the brane.Comment: 24 pages, latex, 4 eps figur
Epifania, recriação e ressentimento: fragmentos narrativos sobre a experiĂȘncia da viagem na imigração italiana no Brasil
L'expérience du voyage dans le processus de l'immigration marque le premier contact avec l'inconnu. L'aventure de la traversée de l'océan signifie par conséquent l'abandon du seul monde tangible. Le nouveau monde va se dévoiler à l'émigrant au fur et à mesure que le navire avance en mer, en un mélange de représentations produites avant le départ et de
nouvelles âidĂ©es-imagesâ que l'expĂ©rience elle-mĂȘme du voyage contribue Ă Ă©laborer en continu. Au cours de ce processus, la lecture de "Sull'Oceano" dâEdmondo De Amicis permet une immersion dans ce monde fragmentaire d'images et des rĂ©cits que l'Ă©migrant va produire. Il tente par ce biais de comprendre sa propre expĂ©rience et son existence, en un monde entrecroisĂ© de diffĂ©rentes expressions de la sensibilitĂ©. LĂȘ nouveau monde se rĂ©vĂšle, souvenir tout Ă la fois dâune terre que lâon a abandonnĂ©e et recrĂ©ation d'une reprĂ©sentation pacificatrice
Solving the Hierarchy Problem without Supersymmetry or Extra Dimensions: An Alternative Approach
In this paper, we propose a possible new approach towards solving the gauge
hierarchy problem without supersymmetry and without extra spacetime dimensions.
This approach relies on the finiteness of string theory and the conjectured
stability of certain non-supersymmetric string vacua. One crucial ingredient in
this approach is the idea of ``misaligned supersymmetry'', which explains how
string theories may be finite even without exhibiting spacetime supersymmetry.
This approach towards solving the gauge hierarchy problem is therefore
complementary to recent proposals involving both large and small extra
spacetime dimensions. This approach may also give a new perspective towards
simultaneously solving the cosmological constant problem.Comment: 33 pages, LaTeX, 3 figure
A Mechanism for Ordinary-Sterile Neutrino Mixing
Efficient oscillations between ordinary (active) and sterile neutrinos can
occur only if Dirac and Majorana mass terms exist which are both small and
comparable. It is shown that this can occur naturally in a class of string
models, in which higher-dimensional operators in the superpotential lead to an
intermediate scale expectation value for a scalar field and to suppressed Dirac
and Majorana fermion masses.Comment: 12 page
The structure of intelligence in children with specific learning disabilities is different as compared to typically development children
Children with specific learning disabilities (SLDs) are characterized by a poor academic achievement despite an average intelligence. They are therefore typically assessed not only with achievement tests, but also with intelligence tests, usually the Wechsler Intelligence Scale for Children (WISC). The assumption of a discrepancy between IQ and achievement in children with SLD has been questioned, however, and the implications of using different measures in batteries of intellectual subtests have not been thoroughly investigated. The present study examined these issues, taking advantage of a large database of scores obtained in the ten core subtests of the WISC-IV by a group of 910 Italian children with a clinical diagnosis of SLD, who were compared with the children considered for national standardization purposes. Our results support the doubts raised concerning the IQ-achievement discrepancy model, showing that relevant discrepancies can emerge even within the WISC profile. The four main WISC-IV indexes were found differently related to intelligence (measured by means of the g-factor) and the g content of many subtests differed in childrenwith SLD vis-\ue0-vis typically-developing children. These results have important implications both theoretical, indicating that the g-factor isweakly identified in children with SLD children, and practical, indicating that the QI obtained with the WISC-IV may not be a good measure of intellectual functioning for children with SLD, which are discussed
Introduction
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