1,718 research outputs found

    The Powfoot Boulder Pavement

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    Lessons from Fiascos in Russian Corporate Governance

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    "Bad corporate governance" is often invoked to explain poor enterprise performance, but the catch phrase is never precisely defined - neither its consequences for the real economy, nor its causes in particular countries has been adequately explained. This paper uses Russian enterprise examples to address these open questions in corporate governance theory. We define corporate governance by looking to the economic functions of the firm rather than to any particular set of national corporate laws. Firms exhibit good corporate governance when their managers maximize residuals and, in the case of investor-owned firms, make pro rata distributions to shareholders. First, using this definition, we develop a typology that shows the channels through which bad corporate governance can inflict damage on the real economy. The topology helps identify vulnerabilities to corporate governance problems that may appear in any country and it suggests a new way to tailor policy responses. Second, we explain the causes of poor corporate performance in Russia by looking to the particular conditions prevailing at privatization - untenable initial firm boundaries and insider allocation of firm shares - and the bargaining dynamics that followed. The focus on initial conditions helps expand a comparative corporate governance literature built on United States, Western European, and Japanese models. Lessons from Russian fiascos counsel caution as to "stakeholder" proposals - including labor or local communities in formal corporate governance - and generate testable hypotheses regarding potential losses from the multiple large block share ownerships typical of many U.S. firms, especially close corporations.

    Dose-volume-based IMRT fluence optimization: A fast least-squares approach with differentiability

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    AbstractIn intensity-modulated radiation therapy (IMRT) for cancer treatment, the most commonly used metric for treatment prescriptions and evaluations is the so-called dose-volume constraint (DVC). These DVCs induce much needed flexibility but also non-convexity into the fluence optimization problem, which is an important step in the IMRT treatment planning. Currently, the models of choice for fluence optimization in clinical practice are weighted least-squares models. When DVCs are directly incorporated into the objective functions of least-squares models, these objective functions become not only non-convex but also non-differentiable. This non-differentiability is a problem when software packages designed for minimizing smooth functions are routinely applied to these non-smooth models in commercial IMRT planning systems. In this paper, we formulate and study a new least-squares model that allows a monotone and differentiable objective function. We devise a greedy approach for approximately solving the resulting optimization problem. We report numerical results on several clinical cases showing that, compared to a widely used existing model, the new approach is capable of generating clinically relevant plans at a much faster speed. This improvement can be more than one-order of magnitude for some large-scale problems

    Photonic Integrated Circuits

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    Integrated photonics generally is the integration of multiple lithographically defined photonic and electronic components and devices (e.g. lasers, detectors, waveguides passive structures, modulators, electronic control and optical interconnects) on a single platform with nanometer-scale feature sizes. The development of photonic integrated circuits permits size, weight, power and cost reductions for spacecraft microprocessors, optical communication, processor buses, advanced data processing, and integrated optic science instrument optical systems, subsystems and components. This is particularly critical for small spacecraft platforms. We will give an overview of some NASA applications for integrated photonics

    Sequentially consistent versus linearizable counting networks

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    We compare the impact of timing conditions on implementing sequentially consistent and linearizable counters using (uniform) counting networks in distributed systems. For counting problems in application domains which do not require linearizability but will run correctly if only sequential consistency is provided, the results of our investigation, and their potential payoffs, are threefold: • First, we show that sequential consistency and linearizability cannot be distinguished by the timing conditions previously considered in the context of counting networks; thus, in contexts where these constraints apply, it is possible to rely on the stronger semantics of linearizability, which simplifies proofs and enhances compositionality. • Second, we identify local timing conditions that support sequential consistency but not linearizability; thus, we suggest weaker, easily implementable timing conditions that are likely to be sufficient in many applications. • Third, we show that any kind of synchronization that is too weak to support even sequential consistency may violate it significantly for some counting networks; hence

    Corporate Governance Lessons from Russian Enterprise Fiascoes

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    This Article draws on a rich array of deviant behavior in Russian enterprises to craft lessons for corporate governance theory. First, Professors Fox and Heller define corporate governance by looking to the economic functions of the firm. Based on this definition, they develop a typology that comprehensively shows all the channels through which bad corporate governance can inflict damage on a country\u27s real economy. Second, they explain the causes of Russian enterprise fiascoes by looking to the particular initial conditions prevailing at privatization – untenable firm boundaries and insider allocation of firm shares – and the bargaining dynamics that have followed. This focus offers a new perspective for a comparative corporate governance literature derived from United States, Western European, and Japanese models. The analytic tools created in this Article can inform pressing debates across contemporary corporate law, ranging from the theory of the close corporation to the viability of stakeholder proposals

    BOTPPI, a New Wittig Salt Used in the Synthesis of 12-(S)-Hydroxy-Eicosatetraenoic Acid [12-(S)-HETE]

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    An efficient route to (Z)-(8-benzyloxy-8-oxooct-3-en-1-yl)triphenylphosphonium iodide, or BOTPPI, is disclosed, complete with full experimental details, NMR spectra, and HRMS data. BOTPPI serves as a surrogate for (Z)-(8-methoxy-8-oxooct-3-en-1-yl)triphenylphosphonium iodide, or MOTPPI, a Wittig salt previously used in two 12-HETE syntheses. BOTPPI has the advantage over MOTPPI of being derived from a sequence for which every intermediate is UV-active and amenable to large-scale chromatographic purification. A formal asymmetric total synthesis of 12-(S)-HETE is also reported, involving a stereoselective phase-transfer catalyzed (PTC) alkylation in its key step

    Far Ultraviolet Spectroscopy of Seven Nova-Like Variables

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    We present the results of a multi-component synthetic spectral analysis of the archival far ultraviolet spectra of several key nova-like variables including members of the SW Sex, RW Tri, UX UMa and VY Scl subclasses: KR Aur, RW Tri, V825 Her, V795 Her, BP Lyn, V425 Cas and HL Aqr. Accretion rates as well as the possible flux contribution of the accreting white dwarf are included in our analysis. Except for RW Tri which has a reliable trigonometric parallax, we computed the distances to the nova-like systems using the method of Knigge (2006). Our analysis of seven archival IUE spectra of RW Tri at its parallax distance of 341 pc consistently indicates a low mass (0.4Msun) white dwarf and an average accretion rate, 6.3 E-9Msun/yr. For KR Aur, we estimate that the white dwarf has Teff=29,000K, log g = 8.4 and contributes 18% of the FUV flux while an accretion disk with accretion rate of 3 E-10Msun/yr at an inclination of 41 degrees, contributes the remainder. We find that an accretion disk dominates the far UV spectrum of V425 Cas but a white dwarf contributes non-negligibly with approximately 18% of the FUV flux. For the two high state nova-likes, HL Aqr and V825 Her, their accretion disks totally dominate with 1 E-9Msun/yr and 3 E-9Msun/yr, respectively. For BP Lyn we find an accretion rate of 1 E-8Msun/yr while for V795 Her, we find an accretion rate of 1 E-10Msun/yr. We discuss the implications of our results for the evolutionary status of nova-like variables.Comment: ApJ, accepte
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