840 research outputs found

    The Unintended Consequences of Enhancing Gun Penalties: Shooting Down the Commerce Clause and Arming Federal Prosecutors

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    The objective of this work is to derive an MIQP solver tailored for MPC. The MIQP solver is built on the branch and bound method, where QP relaxations of the original problem are solved in the nodes of a binary search tree. The difference between the subproblems is often small and therefore it is interesting to be able to use a previous solution as a starting point in a new subproblem. This is referred to as a warm start of the solver. Because of its good warm start properties, a dual active set QP method was chosen. The method is tailored for MPC by solving a part of the KKT system using a Riccati recursion, which makes the computational complexity of the QP iterations grow linearly with the prediction horizon. Simulation results are presented both for the QP solver itself and when it is incorporated as a part of the MIQP solver. In both cases the computational complexity is significantly reduced compared to if a primal active set solver not utilizing structure is used

    EC Maritime Transport Policy and Regulation

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    When designing robust controllers, H-infinity synthesis is a common tool touse. The controllers that result from these algorithms are typically of very high order, which complicates implementation. However, if a constraint on the maximum order of the controller is set, that is lower than the order of the (augmented) system, the problem becomes nonconvex and it is relatively hard to solve. These problems become very complex, even when the order of the system is low. The approach used in this work is based on formulating the constraint onthe maximum order of the controller as a polynomial (or rational) equation.This equality constraint is added to the optimization problem of minimizingan upper bound on the H-innity norm of the closed loop system subjectto linear matrix inequality (LMI) constraints. The problem is then solvedby reformulating it as a partially augmented Lagrangian problem where theequality constraint is put into the objective function, but where the LMIsare kept as constraints. The proposed method is evaluated together with two well-known methodsfrom the literature. The results indicate that the proposed method hascomparable performance in most cases, especially if the synthesized con-troller has many parameters, which is the case if the system to be controlledhas many input and output signals

    Luminosities of High-Redshift Objects in an Accelerating Universe

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    The results from the Supernova Cosmology Project indicate a relation between cosmic distance and redshift that corresponds to an accelerating Universe, and, as a consequence, the presence of an energy component with negative pressure. This necessitates a re-evaluation of such astrophysical luminosities that have been derived through conventional redshift analyses of, e.g., gamma-ray bursts and quasars. We have calculated corrected luminosity distances within two scenarios; the standard one with a non-zero cosmological constant, and the more recently proposed ``quintessence'', with a slowly evolving energy-density component. We find luminosity corrections from +30 to -40 per cent for redshifts with z=010z=0 - 10. This finding implicates that the SCP data do not, by themselves, require a revision of the current, rather qualitative modeling of gamma-ray bursts and quasar properties.Comment: RevTeX, 4 pages, 2 postscript figures, submitted to PR

    Sometimes the Silence Can Be like the Thunder: Access to Pharmaceutical Data at the FDA

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    Those committed to the free exchange of scientific information have long complained about various restrictions on access to the FDA\u27s pharmaceutical data and the resultant restrictions on open discourse. A review of open-government procedures and litigation at the FDA demonstrates that the need for transparency at the agency extend well beyond the reach of any clinical trial registry

    SZZ Unleashed: An Open Implementation of the SZZ Algorithm -- Featuring Example Usage in a Study of Just-in-Time Bug Prediction for the Jenkins Project

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    Numerous empirical software engineering studies rely on detailed information about bugs. While issue trackers often contain information about when bugs were fixed, details about when they were introduced to the system are often absent. As a remedy, researchers often rely on the SZZ algorithm as a heuristic approach to identify bug-introducing software changes. Unfortunately, as reported in a recent systematic literature review, few researchers have made their SZZ implementations publicly available. Consequently, there is a risk that research effort is wasted as new projects based on SZZ output need to initially reimplement the approach. Furthermore, there is a risk that newly developed (closed source) SZZ implementations have not been properly tested, thus conducting research based on their output might introduce threats to validity. We present SZZ Unleashed, an open implementation of the SZZ algorithm for git repositories. This paper describes our implementation along with a usage example for the Jenkins project, and conclude with an illustrative study on just-in-time bug prediction. We hope to continue evolving SZZ Unleashed on GitHub, and warmly invite the community to contribute

    Introducing Agile Principles and Management to a Library Organization

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    Libraries are pressured to adapt to changing conditions due to user demands, behavior, emerging technologies and a need for cost-efficient solutions. Software companies have turned to agile development to stay competitive and to deliver working solutions in a short timeframe. Agile processes are built upon co-operation, iterative workflows and delivering working solutions with a high business value. Agile development and management in an agile organization constitutes a controlled framework of principles with a promise to ensure that the organization focuses on the right things and is able to adapt to new needs. The Library at Chalmers University of Technology in Sweden introduced agile software development in 2011 as a part of the work with the institutional repository. Following the success of introducing Scrum to system developers the formation of cross-disciplinary teams for other projects involved librarians. One of the projects for a cross-disciplinary team was to develop a brand new website. Drawing upon the experience of Scrum and with a focus on User Experience design (UX) the team was able to define an agile methodology involving different competences at the library. As other projects formed and adopted the principles of Scrum and agile the methodology spread throughout the library organization as it was re-organized. Managing an agile oriented organization can be challenging. Senior management has been forced to work with allocating resources, input to prioritization, sprint planning and judging business value thus forcing a transparency to appear in the organization and exposing its operations. Chalmers Library is still exploring the possibilities and challenges of working with agile development and management. It is an iterative and evolving process, but the benefits far outweigh the drawbacks as the organization can learn and respond to change, re-prioritize how resources are allocated, avoid knowledge silos, build strong teams and identify uncertainties early. As of January 1st 2014 the library organization changed and introduced agile principles throughout all operations

    A Quasi-Newton Interior Point Method for Low Order H-Infinity Controller Synthesis

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    Immunotherapy with tolerogenic apolipoprotein B-100–loaded dendritic cells attenuates atherosclerosis in hypercholesterolemic mice

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    BACKGROUND: Atherosclerosis is a chronic inflammatory disease characterized by a massive intimal accumulation of low-density lipoprotein that triggers chronic vascular inflammation with an autoimmune response to low-density lipoprotein components. METHODS AND RESULTS: To dampen the inflammatory component of atherosclerosis, we injected hypercholesterolemic huB100(tg) × Ldlr(-/-) mice (mice transgenic for human apolipoprotein B100 [ApoB100] and deficient for the low-density lipoprotein receptor) intravenously with dendritic cells (DCs) that had been pulsed with the low-density lipoprotein protein ApoB100 in combination with the immunosuppressive cytokine interleukin-10. DCs treated with ApoB100 and interleukin-10 reduced proliferation of effector T cells, inhibited production of interferon-γ, and increased de novo generation of regulatory T cells in vitro. Spleen cells from mice treated with DCs plus ApoB100 plus interleukin-10 showed diminished proliferative responses to ApoB100 and significantly dampened T-helper 1 and 2 immunity to ApoB100. Spleen CD4(+) T cells from these mice suppressed activation of ApoB100-reactive T cells in a manner characteristic of regulatory T cells, and mRNA analysis of lymphoid organs showed induction of transcripts characteristic of these cells. Treatment of huB100(tg) × Ldlr(-/-) mice with ApoB100-pulsed tolerogenic DCs led to a significant (70%) reduction of atherosclerotic lesions in the aorta, with decreased CD4(+) T-cell infiltration and signs of reduced systemic inflammation. CONCLUSIONS: Tolerogenic DCs pulsed with ApoB100 reduced the autoimmune response against low-density lipoprotein and may represent a novel possibility for treatment or prevention of atherosclerosis.Swedish Research CouncilFoundation for Strategic ResearchVinnovaSwedish Heart-Lung FoundationEuropean Union (AtheroRemo integrated project)Stockholm County CouncilPublishe
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