10,045 research outputs found

    The Atomic and Electronic Structure of Liquid N- Methylformamide as Determined from Diffraction Experiments

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    The structure of liquid N-methylformamide (NMF) has been investigated using synchrotron radiation at 77 and 95 keV. The use of high energy photons has several advantages, in this case especially the large accessible momentum transfer range, the low absorption and the direct comparability with neutron diffraction. The range of momentum transfer covered is 0.6 \AA−1<^{-1} < Q <<24.0 \AA−1^{-1}. Neutron diffraction data on the same sample in the same momentum transfer range have been published previously. In that study two differently isotope - substituted species were investigated. In order to compare neutron and photon diffraction data properly Reverse Monte Carlo (RMC-) simulations have been performed. Some modifications had to be added to the standard RMC- code introducing different constraints for inter- and intramolecular distances as these distances partly overlap in liquid NMF. RMC- simulations having only the neutron data as input were carried out in order to test the quality of the X-ray data. The photon structure factor calculated from the RMC- configurations is found to agree well with the present experimental data, while it deviates considerably from earlier X-ray work using low energy photons (17 keV). Finally we discuss whether the different interaction mechanisms of neutrons and photons can be used to directly access the electronic structure in the liquid. Evidence is presented that the elastic self scattering part of liquid NMF is changed with respect to the independent atom approximation. This modification can be accounted for by a simple charged atoms model.Comment: Accepted for publication in Molecular Physics, LaTex file, 12 pages, figures not include

    Asset Sales, Firm Performance, and the Agency Costs of Managerial Discretion

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    We argue that management sells assets when doing so provides the cheapest funds to pursue its objectives rather than for operating efficiency reasons alone. This hypothesis suggests that (1) firms selling assets have high leverage and/or poor performance, (2) a successful asset sale is good news and (3) the stock market discounts asset sale proceeds retained by the selling firm. In support of this hypothesis, we find that the typical firm in our sample performs poorly before the sale and that the average stock-price reaction to asset sales is positive only when the proceeds are paid out.

    Do People Make Strategic Moves? Experimental Evidence on Strategic Information Avoidance

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    The strategic commitment moves that game theory predicts players make may sometimes seem counter-intuitive. We therefore conducted an experiment to see if people make the predicted strategic move. The experiment uses a simple bargaining situation. A player can make a strategic move of committing to not seeing what another player will demand. Our data show that subjects do, but only after substantial time, learn to make the predicted strategic move. We find only weak evidence of physical timing effects.strategic moves; commitment; bargaining; strategic value of information; physical timing effects; endogenous timing; experiment

    Biodynamic Parameters During a Step Down Task in Subjects with Chronic or Recurrent Low Back Pain Classified with Lumbar Instability

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    Background: Low back pain (LBP) affect a majority of the population. Lumbar instability has been identified as a factor in a significant portion of individuals with LBP but movement characteristics of this population has seen limited research regarding functional tasks. Objective: This study examined biodynamic parameters during a step task. Design: Quasi-experimental with 2 factors, group and side (L/R), and 1 repeated measure (stepping). Statistics: Two-way Mixed-Design Repeated Measures ANOVA with Alpha = .05. Movement task: Subjects with LBP and lumbar spine clinical instability classification (N=11) and control subjects (N=11) performed a step down task from a 9.5 inch height on left and right side. Main outcomes: sEMG activation (%MVC), sEMG onset time at first weight acceptance, Ground Reaction Force; rise time GRF(z) and 3D trunk range of motion (ROM) related to three phases of the step: (1) First single leg support, (2) double support and (3) second single leg support. Main results: ROM was reduced in the LBP group in the full step phase in the sagittal plane (p=.003, power= .99), in the final phase in the frontal plane (p=.021, power=.99) and in the transverse plane (p=.018, power=.99) on left steps. GRF(z) was slower in the LBP group at first weight acceptance when leading with the left leg (p=.016, power= .99). EMG onsets: The LBP group had delayed muscle onsets of the right hip abductors (p=.043, power=.99), left abdominals with left stepping (p=.008, power=.91) and right lumbar extensors with right stepping (p=.025, power=.93). The LBP group had delayed onset of right lumbar extensors with right stepping but earlier onset with left stepping (p=.025, power.93). EMG activation levels was higher in the LBP group in both left and right steps of right lumbar extensors (p=.047, power=.93), right hip abductors (p=.017, power= .68) and left hip abductors (p= .035, power= .96). Conclusion: Subjects with LBP demonstrated a high-load movement strategy during this low-load step task with reduced ROM, increased muscle activation, delayed muscle onsets and slow GRF(z) rise time. Left stepping presented more challenge for this group of predominantly right-footed subjects with LBP classified with lumbar instability

    Biodynamic Parameters During a Step Down Task in Subjects with Chronic or Recurrent Low Back Pain Classified with Lumbar Instability

    Get PDF
    Background: Low back pain (LBP) affect a majority of the population. Lumbar instability has been identified as a factor in a significant portion of individuals with LBP but movement characteristics of this population has seen limited research regarding functional tasks. Objective: This study examined biodynamic parameters during a step task. Design: Quasi-experimental with 2 factors, group and side (L/R), and 1 repeated measure (stepping). Statistics: Two-way Mixed-Design Repeated Measures ANOVA with Alpha = .05. Movement task: Subjects with LBP and lumbar spine clinical instability classification (N=11) and control subjects (N=11) performed a step down task from a 9.5 inch height on left and right side. Main outcomes: sEMG activation (%MVC), sEMG onset time at first weight acceptance, Ground Reaction Force; rise time GRF(z) and 3D trunk range of motion (ROM) related to three phases of the step: (1) First single leg support, (2) double support and (3) second single leg support. Main results: ROM was reduced in the LBP group in the full step phase in the sagittal plane (p=.003, power= .99), in the final phase in the frontal plane (p=.021, power=.99) and in the transverse plane (p=.018, power=.99) on left steps. GRF(z) was slower in the LBP group at first weight acceptance when leading with the left leg (p=.016, power= .99). EMG onsets: The LBP group had delayed muscle onsets of the right hip abductors (p=.043, power=.99), left abdominals with left stepping (p=.008, power=.91) and right lumbar extensors with right stepping (p=.025, power=.93). The LBP group had delayed onset of right lumbar extensors with right stepping but earlier onset with left stepping (p=.025, power.93). EMG activation levels was higher in the LBP group in both left and right steps of right lumbar extensors (p=.047, power=.93), right hip abductors (p=.017, power= .68) and left hip abductors (p= .035, power= .96). Conclusion: Subjects with LBP demonstrated a high-load movement strategy during this low-load step task with reduced ROM, increased muscle activation, delayed muscle onsets and slow GRF(z) rise time. Left stepping presented more challenge for this group of predominantly right-footed subjects with LBP classified with lumbar instability

    Doses for Laboratory Animals based on Metabolic Rate

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    The differences in metabolic rates (M) of different mammals often make it difficult to estimate the dose of e.g. anaesthetics from one species to another. It is well known that the mammalian metabolic rate is correlated to the body weight (W), and the relationship between body weight and metabolic rate kan be expressed using the equation:(1) M = 3.8 x W-25Using the assumption, that the dose of e.g. an anaesthetic only depends on the metabolic rate of the animal, a simple mathematic equation can be used in scaling the dose from one species to another: As an example the equation is employed for the calculation of the doses of pentobarbital for a series of different mammals of different size. The calculated doses agree well with the doses reported in the literature. The equation may be of generel usefulness for a quick calculation of a suitable dose level, when the dose level of another species is known

    The Political Economy of the Investment Treaty Regime

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    Investment treaties are some of the most controversial but least understood instruments of global economic governance. Public interest in international investment arbitration is growing and some developed and developing countries are beginning to revisit their investment treaty policies. The Political Economy of the Investment Treaty Regime synthesises and advances the growing literature on this subject by integrating legal, economic, and political perspectives. Based on an analysis of the substantive and procedural rights conferred by investment treaties, it asks four basic questions. What are the costs and benefits of investment treaties for investors, states, and other stakeholders? Why did developed and developing countries sign the treaties? Why should private arbitrators be allowed to review public regulations passed by states? And what is the relationship between the investment treaty regime and the broader regime complex that governs international investment? Through a concise, but comprehensive, analysis, this book fills in some of the many "blind spots" of academics from different disciplines, and is the first port of call for lawyers, investors, policy-makers, and stakeholders trying to make sense of these critical instruments governing investor-state relations
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