2,263 research outputs found

    Executive Pay: Regulation vs. Market Competition

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    The economic slowdown and the active political season are generating calls for imposing new regulations on executive pay. The presidential candidates of the two major parties have lashed out at what they perceive to be excessive pay for certain executives or for corporate executives in general. Such populist sentiments are often based on misunderstandings about the role of corporate executives in the economy and the vigorous competition that exists for these highly skilled leaders. In the past, federal regulatory efforts based on such misunderstandings have generated unintended consequences, which have damaged the economy and hurt the ability of the market for executives to self-regulate over time. The labor market for executives and the associated pay levels are already subject to high levels of regulation. Indeed, U.S. corporations are subject to more stringent executive pay disclosure requirements than corporations anywhere else in the world. Before additional regulatory and legislative efforts are unleashed, policymakers should examine the rationale for current pay structures and the strong links between executive pay and corporate performance. The misperceptions that drive regulatory efforts are grounded in the idea that the market for executives is not competitive and that pay levels do not reflect supply and demand for talent. Critics claim that executives essentially set their own pay through their influence over the boards of directors of corporations. This "myth of managerial power" leads some policy makers to conclude that greater government regulation is necessary because the market is "rigged." However, a large body of empirical research documents that labor markets for executives are indeed competitive, and that pay levels track corporate performance. This study examines the market forces that set the parameters of executive compensation, the process that boards use to determine pay packages, and the data that indicate the efficient workings of the current "pay-for-performance" model. It also discusses the adverse consequences of imposing rules and regulations on an executive compensation system that has helped to generate great wealth for shareholders and millions of jobs for American workers

    Uniqueness in MHD in divergence form: right nullvectors and well-posedness

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    Magnetohydrodynamics in divergence form describes a hyperbolic system of covariant and constraint-free equations. It comprises a linear combination of an algebraic constraint and Faraday's equations. Here, we study the problem of well-posedness, and identify a preferred linear combination in this divergence formulation. The limit of weak magnetic fields shows the slow magnetosonic and Alfven waves to bifurcate from the contact discontinuity (entropy waves), while the fast magnetosonic wave is a regular perturbation of the hydrodynamical sound speed. These results are further reported as a starting point for characteristic based shock capturing schemes for simulations with ultra-relativistic shocks in magnetized relativistic fluids.Comment: To appear in J Math Phy

    Gravitational radiation from gamma-ray bursts as observational opportunities for LIGO and VIRGO

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    Gamma-ray bursts are believed to originate in core-collapse of massive stars. This produces an active nucleus containing a rapidly rotating Kerr black hole surrounded by a uniformly magnetized torus represented by two counter-oriented current rings. We quantify black hole spin-interactions with the torus and charged particles along open magnetic flux-tubes subtended by the event horizon. A major output of Egw=4e53 erg is radiated in gravitational waves of frequency fgw=500 Hz by a quadrupole mass-moment in the torus. Consistent with GRB-SNe, we find (i) Ts=90s (tens of s, Kouveliotou et al. 1993), (ii) aspherical SNe of kinetic energy Esn=2e51 erg (2e51 erg in SN1998bw, Hoeflich et al. 1999) and (iii) GRB-energies Egamma=2e50 erg (3e50erg in Frail et al. 2001). GRB-SNe occur perhaps about once a year within D=100Mpc. Correlating LIGO/Virgo detectors enables searches for nearby events and their spectral closure density 6e-9 around 250Hz in the stochastic background radiation in gravitational waves. At current sensitivity, LIGO-Hanford may place an upper bound around 150MSolar in GRB030329. Detection of Egw thus provides a method for identifying Kerr black holes by calorimetry.Comment: to appear in PRD, 49

    Hyper- and suspended-accretion states of rotating black holes and the durations of gamma-ray bursts

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    We analyze the temporal evolution of accretion onto rotating black holes subject to large-scale magnetic torques. Wind torques alone drive a disk towards collapse in a finite time tffEk/EB\sim t_{ff} E_k/E_B, where tfft_{ff} is the initial free-fall time and Ek/EBE_k/E_B is the ratio of kinetic-to-poloidal magnetic energy. Additional spin-up torques from a rapidly rotating black hole can arrest the disk's inflow. We associate short/long gamma-ray bursts with hyperaccretion/suspended-accretion onto slowly/rapidly spinning black holes. This model predicts afterglow emission from short bursts, and may be tested by HETE-II.Comment: accepted for publication in the ApJ

    Assessment of insertion techniques and complication rates of dual lumen central venous catheters in patients with hematological malignancies

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    One hundred and twenty-three dual lumen silicone rubber central venous catheters were inserted into 101 patients with hematological malignancies undergoing intensive treatment. There was a perioperative complication rate of 13%. Open and closed techniques for inserting the catheter were compared. The operating time needed for introducing the catheter by the closed technique (average, 51 minutes) was significantly shorter (p< 0.001) than the time needed for the open technique (70 minutes), whereas complication rates were equal in both techniques. On average, the catheters functioned for 149 days. Complications leading to removal were observed in 29.3% of patients, most of which were catheter-related infections (20.4%). Thromboembolic complications leading to removal were less frequent (4.1%) and appeared significantly earlier (p<0.001). These data indicate that introduction of the catheter by direct puncture of the subclavian vein is a quick and safe technique, and that this type of catheter is suitable for long-term use, both for infusion and for blood sampling

    Fostering a Paradigm Shift in the Roles of Health Promotion Education in Southeast Asia

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    In the context of an evolving domain and the complexity globalization adds to the situation, health promotion practice in Southeast Asia face challenges posed by the growing gaps between practice needs, human resource development needs, and educational program development needs. One of the challenges is how to foster a much needed paradigm shift among those responsible for workforce production in health promotion. In this paper, we provide practical proposals for action that provide leverage in thinking differently about health promotion practice. These proposals reflect the authors’ perspectives and experiences in competencies relevant to health promotion key action areas: empowerment, health services, partnerships and alliances, environments, and health and policy. We first describe the developments in the health promotion domain; summarize competency frameworks for health promotion; to arrive at a comparison of Southeast Asia education programs for health promotion with programs in socio-economic advanced regions. We suggest proposals on the way forward aimed at fueling the required paradigm shift in capacity building for health promotion in Southeast Asia; and conclude by considering the role national and international alliances can play in implementing these proposals and improving workforce production for health promotion in Southeast Asia. Keywords: Southeast Asia, health promotion, challenge, educatio

    Electron-positron outflow from black holes

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    Gamma-ray bursts (GRBs) appear as the brightest transient phenomena in the Universe. The nature of the central engine in GRBs is a missing link in the theory of fireballs to their stellar mass progenitors. Here it is shown that rotating black holes produce electron-positron outflow when brought into contact with a strong magnetic field. The outflow is produced by a coupling of the spin of the black hole to the orbit of the particles. For a nearly extreme Kerr black hole, particle outflow from an initial state of electrostatic equilibrium has a normalized isotropic emission of 5×1048(B/Bc)2(M/7M)2sin2θ\sim 5\times10^{48}(B/B_c)^2(M/7M_\odot)^2\sin^2\theta erg/s, where B is the external magnetic field strength, B_c=4.4 x 10^{13}G, and M is the mass of the black hole. This initial outflow has a half-opening angle θBc/3B\theta\ge\sqrt{B_c/3B}. A connection with fireballs in γ\gamma-ray bursts is given.Comment: 10 pages LaTe

    Testing the paradox of enrichment along a land use gradient in a multitrophic aboveground and belowground community

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    In the light of ongoing land use changes, it is important to understand how multitrophic communities perform at different land use intensities. The paradox of enrichment predicts that fertilization leads to destabilization and extinction of predator-prey systems. We tested this prediction for a land use intensity gradient from natural to highly fertilized agricultural ecosystems. We included multiple aboveground and belowground trophic levels and land use-dependent searching efficiencies of insects. To overcome logistic constraints of field experiments, we used a successfully validated simulation model to investigate plant responses to removal of herbivores and their enemies. Consistent with our predictions, instability measured by herbivore-induced plant mortality increased with increasing land use intensity. Simultaneously, the balance between herbivores and natural enemies turned increasingly towards herbivore dominance and natural enemy failure. Under natural conditions, there were more frequently significant effects of belowground herbivores and their natural enemies on plant performance, whereas there were more aboveground effects in agroecosystems. This result was partly due to the “boom-bust” behavior of the shoot herbivore population. Plant responses to herbivore or natural enemy removal were much more abrupt than the imposed smooth land use intensity gradient. This may be due to the presence of multiple trophic levels aboveground and belowground. Our model suggests that destabilization and extinction are more likely to occur in agroecosystems than in natural communities, but the shape of the relationship is nonlinear under the influence of multiple trophic interactions.
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