2,190 research outputs found

    Recent Developments in the Law of the Sea IV: A Synopsis

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    This Article presents an annual synopsis of important events pertaining to the law of the sea which occurred between February 1, 1972, and January 31, 1973. Our major sources of information included the New York Times, the Environmental Reporter, the United States Code Congressional and Administrative News, the Congressional Record, the United Nations Chronicle, and International Legal Materials. It is our hope that the search through a seemingly endless array of indices, newspapers, microfilms, and dusty shelves will prove to be of value. We regret that the synopsis must once again report more problems than solutions, but it is with great optimism that we look to the forthcoming United Nations Conference on the Law of the Sea. Perhaps the next synopsis will report some far-reaching accomplishments of that Conference. Finally, we express our sincerest appreciation to Professor H. Gary Knight. His faith in the value of the synopsis has been a great encouragement

    ARPES and NMTO Wannier Orbital Theory of LiMo6_{6}O17_{17} - Implications for Unusually Robust Quasi-One Dimensional Behavior

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    We present the results of a combined study by band theory and angle resolved photoemission spectroscopy (ARPES) of the purple bronze, Li1x_{1-x}Mo6_{6}O17_{17}. Structural and electronic origins of its unusually robust quasi-one dimensional (quasi-1D) behavior are investigated in detail. The band structure, in a large energy window around the Fermi energy, is basically 2D and formed by three Mo t2gt_{2g}-like extended Wannier orbitals, each one giving rise to a 1D band running at a 120^\circ angle to the two others. A structural "dimerization" from c/2\mathbf{c}/2 to c\mathbf{c} gaps the xzxz and yzyz bands while leaving the xyxy bands metallic in the gap, but resonantly coupled to the gap edges and, hence, to the other directions. The resulting complex shape of the quasi-1D Fermi surface (FS), verified by our ARPES, thus depends strongly on the Fermi energy position in the gap, implying a great sensitivity to Li stoichiometry of properties dependent on the FS, such as FS nesting or superconductivity. The strong resonances prevent either a two-band tight-binding model or a related real-space ladder picture from giving a valid description of the low-energy electronic structure. We use our extended knowledge of the electronic structure to newly advocate for framing LiMo6_{6}O17_{17} as a weak-coupling material and in that framework can rationalize both the robustness of its quasi-1D behavior and the rather large value of its Luttinger liquid (LL) exponent α\alpha. Down to a temperature of 6\,K we find no evidence for a theoretically expected downward renormalization of perpendicular single particle hopping due to LL fluctuations in the quasi-1D chains.Comment: 53 pages, 17 Figures, 6 year

    Product Measure Steady States of Generalized Zero Range Processes

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    We establish necessary and sufficient conditions for the existence of factorizable steady states of the Generalized Zero Range Process. This process allows transitions from a site ii to a site i+qi+q involving multiple particles with rates depending on the content of the site ii, the direction qq of movement, and the number of particles moving. We also show the sufficiency of a similar condition for the continuous time Mass Transport Process, where the mass at each site and the amount transferred in each transition are continuous variables; we conjecture that this is also a necessary condition.Comment: 9 pages, LaTeX with IOP style files. v2 has minor corrections; v3 has been rewritten for greater clarit

    Non-Fermi liquid angle resolved photoemission lineshapes of Li0.9Mo6O17

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    A recent letter by Xue et al. (PRL v.83, 1235 ('99)) reports a Fermi-Liquid (FL) angle resolved photoemission (ARPES) lineshape for quasi one-dimensional Li0.9Mo6O17, contradicting our report (PRL v.82, 2540 ('99)) of a non-FL lineshape in this material. Xue et al. attributed the difference to the improved angle resolution. In this comment, we point out that this reasoning is flawed. Rather, we find that their data have fundamental differences from other ARPES results and also band theory.Comment: To be published as a PRL Commen

    ITS 1.5 Reference Manual

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    This reference manual consists of two parts. The first (sections 1 through 6) is intended for those who are either interested in the ITS 1.5 time sharing monitor for its own sake or who wish to write machine language programs to run under it. Some knowledge of PDP-6 (or PDP-10) machine language is useful in reading this part. The second part (sections 7, 8, and 9) describes three programs that run under ITS. The first program (DDT) is a modified machine language debugging program that also replaces the "monitor command" level (where the user is typing directly at the monitor) present in most time-sharing systems. The remaining two (PEEK and LOCK) are a status display and a miscellaneous utility program. It should be remembered that the McCulloch Laboratory PDP-6 and PDP-10 installation is undergoing continuous software and hardware development which may rapidly outdate this manual

    Pressure-induced structural transitions triggering dimensional crossover in lithium purple bronze Li0.9M6O17

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    At ambient pressure, lithium molybdenum purple bronze (Li0.9Mo6O17) is a quasi-one dimensional solid in which the anisotropic crystal structure and the linear dispersion of the underlying bands produced by electronic correlations possibly bring about a rare experimental realization of Tomomaga-Luttinger liquid physics. It is also the sole member of the broader purple molybdenum bronzes family where a Peierls instability has not been identified at low temperatures. The present study reports a pressure-induced series of phase transitions between 0 and 12 GPa. These transitions are strongly reflected in infrared spectroscopy, Raman spectroscopy, and x-ray diffraction. The most dramatic effect seen in optical conductivity is the metallization of the c-axis, concomitant to the decrease of conductivity along the b-axis. This indicates that high pressure drives the material away from its quasi-one dimensional behavior at ambient pressure. While the first pressure-induced structure of the series is resolved, the identification of the underlying mechanisms driving the dimensional change in the physics remains a challenge.Comment: 10 pages, 12 figure

    Bioavailability assessment: Methods to estimate total area (AUC 0-∞) and total amount excreted (A e ∞ ) and importance of blood and urine sampling scheme with application to digoxin

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    Five methods are compared to estimate the total area under the digoxin plasma or serum concentrationtime curve (AUC0-∞) after a single dose of drug. To obtain accurate estimates of AUC0-∞, data required are concentrations at a sufficient number of sampling times to define adequately the concentration-time curve prior to the log-linear phase, and at least three, but preferably four or more equally spaced points in the terminal loglinear phase. One method (designated Method I) requires a digital computer; another (Method III) is the classical method (these two methods do not require equally spaced points in the loglinear phase). Method IIA is the accelerated convergence method of Amidon et al.; Methods IIB and IIC are modifications of this method, but incorporate usual and orthogonal least squares, respectively, which make them more accurate with real (noisy) data. Methods I and IICgave very comparable estimates of AUC0-∞. Results indicate that digoxin administered orally in aqueous solution was completely (100%) absorbed when bioavailability estimates were based on oral and intravenous AUC0-∞ estimates and the actual doses, whereas formerly only about 80% absorption was reported, based on areas, under plasma concentration curves which were truncated at 96 hr. It is shown that the sampling scheme of blood can produce biased apparent bioavailability estimates when areas under truncated curves are employed, but an appropriate sampling scheme and application of method IIyield accurate bioavailability estimates. This is important particularly in those bioavailability studies where one is attempting to determine the appropriate label dose for a new “fastrelease” digoxin preparation relative to the label dose and bioavailability of currently marketed tablets. It is shown that the magnitudes and variability of apparent elimination rate constants and halflives of digoxin, estimated from urinary excretion data by the σ − method, depend on which value of A e ∞ is used. The formerly reported greater interindividual variability of AUC data compared to At data for digoxin is explained in that the AUCs, but not the A e ,'s, involve the renal clearance, which exhibits considerable inter- and intraindividual variation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45073/1/10928_2005_Article_BF01061733.pd

    Coriolis Effect on Dynamic Stall in a Vertical Axis Wind Turbine at Moderate Reynolds Number

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    The immersed boundary method is used to simulate the flow around a two-dimensional rotating NACA 0018 airfoil at sub-scale Reynolds number in order to investigate the separated flow occurring on a vertical-axis wind turbine. The influence of dynamic stall on the forces is characterized as a function of tip-speed ratio. The influence of the Coriolis effect is also investigated by comparing the rotating airfoil to one undergoing a equivalent planar motion, which is composed of surging and pitching motions that produce an equivalent speed and angle-of-attack variation over the cycle. When the angle of attack of a rotating airfoil starts to decrease in the upwind half cycle, the Coriolis force leads to a wake-capturing phenomenon of a vortex pair at low tip-speed ratio. This effects occurs at a slightly different phase in each cycle and leads to a significant decrease in the average lift during the downstroke phase. Moreover, the wake-capturing is only observed when the combination of surging, pitching, and Coriolis force are present. Finally, an actuator model is placed at an appropriate location on the suction side of the airfoil surface to control the wake-capturing phenomenon. Based on preliminary simulations, a momentum coefficient above 0.02 was able to increase the average lift by more than 70% over the upwind-half cycle

    Lifeworld Inc. : and what to do about it

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    Can we detect changes in the way that the world turns up as they turn up? This paper makes such an attempt. The first part of the paper argues that a wide-ranging change is occurring in the ontological preconditions of Euro-American cultures, based in reworking what and how an event is produced. Driven by the security – entertainment complex, the aim is to mass produce phenomenological encounter: Lifeworld Inc as I call it. Swimming in a sea of data, such an aim requires the construction of just enough authenticity over and over again. In the second part of the paper, I go on to argue that this new world requires a different kind of social science, one that is experimental in its orientation—just as Lifeworld Inc is—but with a mission to provoke awareness in untoward ways in order to produce new means of association. Only thus, or so I argue, can social science add to the world we are now beginning to live in

    Dynamic separation on a pitching and surging airfoil as a model for flow over vertical axis wind turbine blades

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    Vertical axis wind turbine (VAWT) blades undergo dynamic separation due to the large angle of attack variation they experience during a turbine rotation. The flow over a single blade was modeled using a sinusoidally pitching and surging airfoil in a constant free stream flow at a mean chord Reynolds number of 10^5. Two-dimensional, time resolved velocity fields were acquired using particle image velocimetry (PIV). Vorticity contours were used to visualize shear layer and vortex activity. A low order model of dynamic separation was developed using Dynamic Mode Decomposition (DMD). A primary and secondary dynamic separation mode were identified as the critical drivers for the unsteady flow field
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