922 resultados para High-level Design Specification
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As the Greek debt drama reaches another supposedly decision point, Daniel Gros urges creditors (and indeed all policy-makers) to think about the long term and poses one key question in this CEPS High-Level Brief: What can be gained by keeping Greece inside the euro area at “whatever it takes”? As he points out, the US, with its unified politics and its federal fiscal transfer system, is often taken as a model for the Eurozone, and it is thus instructive to consider the longer-term performance of an area of the US which has for years been kept afloat by massive transfers, and which is now experiencing a public debt crisis. The entity in question is Puerto Rico, which is an integral part of the US in all relevant economic dimensions (currency, economic policy, etc.). The dismal fiscal and economic performance of Puerto Rico carries two lessons: 1) Keeping Greece in the eurozone by increasing implicit subsidies in the form of debt forgiveness might create a low-growth equilibrium with increasing aid dependency. 2) It is wrong to assume that, further integration, including a fiscal and political union, would be sufficient to foster convergence, and prevent further problems of the type the EU is experiencing with Greece.
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Os meios urbanos são espaços cada vez mais edificados, compactos e com solos impermeabilizados, onde a ausência ou reduzida presença de espaços verdes é uma realidade. Os elementos arbóreos, qualquer que seja a sua disposição, ganham cada vez mais significado enquanto representantes do meio natural na conservação da qualidade e conforto de vida nas cidades. Este trabalho desenvolveu-se a partir do tema das árvores em meio urbano, tendo por base os benefícios das árvores nas cidades, a sua distribuição espacial e o estado de conservação deste tipo de património. O principal fio condutor passou pela concepção do inventário do Património Arbóreo da cidade de Portalegre, com recurso às novas tecnologias da informação, nomeadamente os Sistemas de Informação Geográfica, capaz de se integrar nos sistemas homólogos do Município de Portalegre. O inventário à escala do perímetro urbano da cidade de Portalegre contabilizou 2087 elementos arbóreos localizados em áreas públicas, dos quais 1500 são árvores de folha caduca e 587 são perenifólias. Registou-se um elevado índice de diversidade para aquela área, cerca de 705 árvores/km2, embora as árvores estejam distribuídas de forma heterogénea pelo território considerado, percebendo-se com isso as zonas de carência de arborização. Com este inventário foi ainda possível conceber uma avaliação económica segundo a Norma de Granada, de 13 árvores isoladas e uma alameda com 38 indivíduos, assim como propor a classificação destes elementos a Árvores de Interesse Público. Anseia-se que este trabalho seja um documento informativo e sensibilizador de todo o público em geral, mas principalmente que se assuma como uma ferramenta útil aos responsáveis pelos espaços verdes da cidade de Portalegre.
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Thesis (Ph.D.)--University of Washington, 2016-06
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Background: Contemporary neuropsychological studies suggest that cerebellar lesions may impact upon higher-level cognitive functioning via mechanisms of crossed cerebello-cerebral diaschisis. Accordingly, right cerebellar lesions have been previously associated with linguistic impairments such as reduced word fluency and agrammatic output. Recently, however, neuroimaging investigations have also identified ipsilateral cerebral hypoperfusion as a consequence of cerebellar lesions, implicating a potential role for the left cerebellum in the mediation of language processes. Aims: The purpose of this research was to investigate the effects of left cerebellar lesions of vascular origin, on general as well as high-level language skills. Methods & Procedures: Linguistic profiles were compiled for five individuals with left primary cerebellar lesions utilising a comprehensive language test battery. Individual scores relevant to each subtest were compared to a group of non-neurologically impaired controls. The criterion for anomalous performance was established as greater than or equal to 1.5 SD below the mean of the control group. Outcomes & Results: The findings of this research suggest that higher-level language deficits may result from left primary cerebellar lesions. All participants demonstrated deficits on measures of word fluency, sentence construction within a set context, producing word definitions, and producing multiple definitions for the same word. Deficits were also noted for several participants on measures of understanding figurative language, forming word associations, identifying and correcting semantic absurdities, and producing synonyms and antonyms. Conclusions: The results presented challenge the notion of a lateralised linguistic cerebellum, supporting a potential role for the left as well as right cerebellar hemispheres in the regulation of language processes, presumably via cerebellar-basal ganglia/thalamo-cortical pathways.
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The Great Barrier Reef Marine Park, an area almost the size , of Japan, has a new network of no-take areas that significantly improves the protection of biodiversity. The new marine park zoning implements, in a quantitative manner, many of the theoretical design principles discussed in the literature. For example, the new network of no-take areas has at least 20% protection per bioregion, minimum levels of protection for all known habitats and special or unique features, and minimum sizes for no-take areas of at least 10 or 20 kat across at the smallest diameter Overall, more than 33% of the Great Barrier Reef Marine Park is now in no-take areas (previously 4.5%). The steps taken leading to this outcome were to clarify to the interested public why the existing level of protection wets inadequate; detail the conservation objectives of establishing new no-take areas; work with relevant and independent experts to define, and contribute to, the best scientific process to deliver on the objectives; describe the biodiversity (e.g., map bioregions); define operational principles needed to achieve the objectives; invite community input on all of The above; gather and layer the data gathered in round-table discussions; report the degree of achievement of principles for various options of no-take areas; and determine how to address negative impacts. Some of the key success factors in this case have global relevance and include focusing initial communication on the problem to be addressed; applying the precautionary principle; using independent experts; facilitating input to decision making; conducting extensive and participatory consultation; having an existing marine park that encompassed much of the ecosystem; having legislative power under federal law; developing high-level support; ensuring agency Priority and ownership; and being able to address the issue of displaced fishers.
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Purpose: Classic lobular carcinomas (CLC) account for 10% to 15% of all breast cancers. At the genetic level, CLCs show recurrent physical loss of chromosome16q coupled with the lack of E-cadherin (CDH1 gene) expression. However, little is known about the putative therapeutic targets for these tumors. The aim of this study was to characterize CLCs at the molecular genetic level and identify putative therapeutic targets. Experimental Design: We subjected 13 cases of CLC to a comprehensive molecular analysis including immunohistochemistry for E-cadherin, estrogen and progesterone receptors, HER2/ neu and p53; high-resolution comparative genomic hybridization (HR-CGH); microarray-based CGH (aCGH); and fluorescent and chromogenic in situ hybridization for CCND1 and FGFR1. Results: All cases lacked the expression of E-cadherin, p53, and HER2, and all but one case was positive for estrogen receptors. HR-CGH revealed recurrent gains on 1q and losses on 16q (both, 85%). aCGH showed a good agreement with but higher resolution and sensitivity than HR-CGH. Recurrent, high level gains at 11q13 (CCND1) and 8p12-p11.2 were identified in seven and six cases, respectively, and were validated with in situ hybridization. Examination of aCGH and the gene expression profile data of the cell lines, MDA-MB-134 and ZR-75-1, which harbor distinct gains of 8p12-p11.2, identified FGFR1 as a putative amplicon driver of 8p12-p11.2 amplification in MDA-MB-134. Inhibition of FGFR1 expression using small interfering RNA or a small-molecule chemical inhibitor showed that FGFR1 signaling contributes to the survival of MDA-MB-134 cells. Conclusions: Our findings suggest that receptor FGFR1 inhibitors may be useful as therapeutics in a subset of CLCs.
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Radio-frequency ( RF) coils are designed such that they induce homogeneous magnetic fields within some region of interest within a magnetic resonance imaging ( MRI) scanner. Loading the scanner with a patient disrupts the homogeneity of these fields and can lead to a considerable degradation of the quality of the acquired image. In this paper, an inverse method is presented for designing RF coils, in which the presence of a load ( patient) within the MRI scanner is accounted for in the model. To approximate the finite length of the coil, a Fourier series expansion is considered for the coil current density and for the induced fields. Regularization is used to solve this ill-conditioned inverse problem for the unknown Fourier coefficients. That is, the error between the induced and homogeneous target fields is minimized along with an additional constraint, chosen in this paper to represent the curvature of the coil windings. Smooth winding patterns are obtained for both unloaded and loaded coils. RF fields with a high level of homogeneity are obtained in the unloaded case and a limit to the level of homogeneity attainable is observed in the loaded case.
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Co-suppression of transgenes and their homologous viral sequences by RNA silencing is a powerful strategy for achieving high-level virus resistance in plants. This review provides a brief overview of RNA silencing mechanisms in plants and discusses important transgene construct design features underpinning successful RNA silencing-mediated transgenic virus control. Application of those strategies to protect horticultural and field crops from virus infection and results of field tests are also provided. The effectiveness and stability of RNA-mediated transgenic resistance are assessed taking into account effects of viral, plant and environmental factors.
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Object-Z allows coupling constraints between classes which, on the one hand, facilitate specification at a high level of abstraction, but, on the other hand, make class refinement non-compositional. The consequence of this is that refinement is not practical for large Systems. This paper overcomes this limitation by introducing a methodology for compositional class refinement in Object-Z. The key step is an equivalence transformation of an arbitrary Object-Z specification to one in which introduced constraints prohibit non-compositional refinements. The methodology also allows the constraints which couple classes to be refined yielding an unrestricted approach to compositional class refinement.
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Security protocols are often modelled at a high level of abstraction, potentially overlooking implementation-dependent vulnerabilities. Here we use the Z specification language's rich set of data structures to formally model potentially ambiguous messages that may be exploited in a 'type flaw' attack. We then show how to formally verify whether or not such an attack is actually possible in a particular protocol using Z's schema calculus.
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Previous work on formally modelling and analysing program compilation has shown the need for a simple and expressive semantics for assembler level programs. Assembler programs contain unstructured jumps and previous formalisms have modelled these by using continuations, or by embedding the program in an explicit emulator. We propose a simpler approach, which uses techniques from compiler theory in a formal setting. This approach is based on an interpretation of programs as collections of program paths, each of which has a weakest liberal precondition semantics. We then demonstrate, by example, how we can use this formalism to justify the compilation of block-structured high-level language programs into assembler.
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This paper details the design of an autonomous helicopter control system using a low cost sensor suite. Control is maintained using simple nested PID loops. Aircraft attitude, velocity, and height is estimated using an in-house designed IMU and vision system. Information is combined using complimentary filtering. The aircraft is shown to be stabilised and responding to high level demands on all axes, including heading, height, lateral velocity and longitudinal velocity.
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-scale vary from a planetary scale and million years for convection problems to 100km and 10 years for fault systems simulations. Various techniques are in use to deal with the time dependency (e.g. Crank-Nicholson), with the non-linearity (e.g. Newton-Raphson) and weakly coupled equations (e.g. non-linear Gauss-Seidel). Besides these high-level solution algorithms discretization methods (e.g. finite element method (FEM), boundary element method (BEM)) are used to deal with spatial derivatives. Typically, large-scale, three dimensional meshes are required to resolve geometrical complexity (e.g. in the case of fault systems) or features in the solution (e.g. in mantel convection simulations). The modelling environment escript allows the rapid implementation of new physics as required for the development of simulation codes in earth sciences. Its main object is to provide a programming language, where the user can define new models and rapidly develop high-level solution algorithms. The current implementation is linked with the finite element package finley as a PDE solver. However, the design is open and other discretization technologies such as finite differences and boundary element methods could be included. escript is implemented as an extension of the interactive programming environment python (see www.python.org). Key concepts introduced are Data objects, which are holding values on nodes or elements of the finite element mesh, and linearPDE objects, which are defining linear partial differential equations to be solved by the underlying discretization technology. In this paper we will show the basic concepts of escript and will show how escript is used to implement a simulation code for interacting fault systems. We will show some results of large-scale, parallel simulations on an SGI Altix system. Acknowledgements: Project work is supported by Australian Commonwealth Government through the Australian Computational Earth Systems Simulator Major National Research Facility, Queensland State Government Smart State Research Facility Fund, The University of Queensland and SGI.
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In this thesis, we consider four different scenarios of interest in modern satellite communications. For each scenario, we will propose the use of advanced solutions aimed at increasing the spectral efficiency of the communication links. First, we will investigate the optimization of the current standard for digital video broadcasting. We will increase the symbol rate of the signal and determine the optimal signal bandwidth. We will apply the time packing technique and propose a specifically design constellation. We will then compare some receiver architectures with different performance and complexity. The second scenario still addresses broadcast transmissions, but in a network composed of two satellites. We will compare three alternative transceiver strategies, namely, signals completely overlapped in frequency, frequency division multiplexing, and the Alamouti space-time block code, and, for each technique, we will derive theoretical results on the achievable rates. We will also evaluate the performance of said techniques in three different channel models. The third scenario deals with the application of multiuser detection in multibeam satellite systems. We will analyze a case in which the users are near the edge of the coverage area and, hence, they experience a high level of interference from adjacent cells. Also in this case, three different approaches will be compared. A classical approach in which each beam carries information for a user, a cooperative solution based on time division multiplexing, and the Alamouti scheme. The information theoretical analysis will be followed by the study of practical coded schemes. We will show that the theoretical bounds can be approached by a properly designed code or bit mapping. Finally, we will consider an Earth observation scenario, in which data is generated on the satellite and then transmitted to the ground. We will study two channel models, taking into account one or two transmit antennas, and apply techniques such as time and frequency packing, signal predistortion, multiuser detection and the Alamouti scheme.
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This thesis deals with the challenging problem of designing systems able to perceive objects in underwater environments. In the last few decades research activities in robotics have advanced the state of art regarding intervention capabilities of autonomous systems. State of art in fields such as localization and navigation, real time perception and cognition, safe action and manipulation capabilities, applied to ground environments (both indoor and outdoor) has now reached such a readiness level that it allows high level autonomous operations. On the opposite side, the underwater environment remains a very difficult one for autonomous robots. Water influences the mechanical and electrical design of systems, interferes with sensors by limiting their capabilities, heavily impacts on data transmissions, and generally requires systems with low power consumption in order to enable reasonable mission duration. Interest in underwater applications is driven by needs of exploring and intervening in environments in which human capabilities are very limited. Nowadays, most underwater field operations are carried out by manned or remotely operated vehicles, deployed for explorations and limited intervention missions. Manned vehicles, directly on-board controlled, expose human operators to risks related to the stay in field of the mission, within a hostile environment. Remotely Operated Vehicles (ROV) currently represent the most advanced technology for underwater intervention services available on the market. These vehicles can be remotely operated for long time but they need support from an oceanographic vessel with multiple teams of highly specialized pilots. Vehicles equipped with multiple state-of-art sensors and capable to autonomously plan missions have been deployed in the last ten years and exploited as observers for underwater fauna, seabed, ship wrecks, and so on. On the other hand, underwater operations like object recovery and equipment maintenance are still challenging tasks to be conducted without human supervision since they require object perception and localization with much higher accuracy and robustness, to a degree seldom available in Autonomous Underwater Vehicles (AUV). This thesis reports the study, from design to deployment and evaluation, of a general purpose and configurable platform dedicated to stereo-vision perception in underwater environments. Several aspects related to the peculiar environment characteristics have been taken into account during all stages of system design and evaluation: depth of operation and light conditions, together with water turbidity and external weather, heavily impact on perception capabilities. The vision platform proposed in this work is a modular system comprising off-the-shelf components for both the imaging sensors and the computational unit, linked by a high performance ethernet network bus. The adopted design philosophy aims at achieving high flexibility in terms of feasible perception applications, that should not be as limited as in case of a special-purpose and dedicated hardware. Flexibility is required by the variability of underwater environments, with water conditions ranging from clear to turbid, light backscattering varying with daylight and depth, strong color distortion, and other environmental factors. Furthermore, the proposed modular design ensures an easier maintenance and update of the system over time. Performance of the proposed system, in terms of perception capabilities, has been evaluated in several underwater contexts taking advantage of the opportunity offered by the MARIS national project. Design issues like energy power consumption, heat dissipation and network capabilities have been evaluated in different scenarios. Finally, real-world experiments, conducted in multiple and variable underwater contexts, including open sea waters, have led to the collection of several datasets that have been publicly released to the scientific community. The vision system has been integrated in a state of the art AUV equipped with a robotic arm and gripper, and has been exploited in the robot control loop to successfully perform underwater grasping operations.