46,023 research outputs found

    Gone but not forgotten

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    In this reminiscence I discuss the influence of Henry Eyring and John Barker upon my life and work. Others, especially my family, have been of even greater personal influence. However, these two great and grand men were of tremendous scientific influence. Of course, others who came before Eyring and Barker, especially Boltzmann and van der Waals and later Onsager and Eyring's contemporary, Kirkwood, have been influential, but only indirectly as I never met them. Eyring and Barker are not the only scientists who have inspired me. Many who influenced me have contributed articles to this special issue or have worked with me. I single out Eyring and Barker because I met them early in my career and because they have passed away and are now present only in spirit. They are gone but should not be forgotten; I take this occasion to remind the readers about these two outstanding scientists and fine men and offer this reminiscence as thanks to them.Comment: 7 pages, 2 figure

    Some simple results for the properties of polar fluids

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    The author's lecture notes concerning the correlation functions and the thermodynamics of a simple polar fluid are summarized. The emphasis is on the dipolar hard sphere fluid and the mean spherical approximation and on the relation of these results to the Clausius-Mossotti and Onsager formulae for the dielectric constant. Previous excerpts from these lecture notes, Condens. Matter Phys., 2009, 12, 127; ibid., 2010, 13, 13002, have contained results that were not widely known. It is hoped that this third, and likely final, excerpt will prove equally helpful by gathering several results together and making these more widely available and recording a few new results.Comment: 17 pages, 3 figure

    Nonmonotonous pressure as a function of the density in a fluid without attractive forces

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    A simple result for the pressure of a hard sphere fluid that was developed many years ago by Rennert is extended in a straightforward manner by adding the terms that are of the same form as the Rennert's formula. The resulting expression is moderately accurate but its accuracy does not necessarily improve as additional terms are included. This expression has the interesting consequence that the pressure can have a maximum, as the density increases, which is consistent with the freezing of hard spheres. This occurs solely as a consequence of repulsive interactions. Only the Born-Green-Yvon and Kirkwood theories show such a behavior for hard spheres and they require a numerical solution of an integral equation. The procedure outlined here is ad hoc but is, perhaps, useful just as the popular Carnahan-Starling equation for the hard sphere pressure is also ad hoc but useful.Comment: 4 pages, 1 figur

    Nonlinear dynamics and pattern formation in turbulent wake transition

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    Results are reported on direct numerical simulations of transition from two-dimensional to three-dimensional states due to secondary instability in the wake of a circular cylinder. These calculations quantify the nonlinear response of the system to three-dimensional perturbations near threshold for the two separate linear instabilities of the wake: mode A and mode B. The objectives are to classify the nonlinear form of the bifurcation to mode A and mode B and to identify the conditions under which the wake evolves to periodic, quasi-periodic, or chaotic states with respect to changes in spanwise dimension and Reynolds number. The onset of mode A is shown to occur through a subcritical bifurcation that causes a reduction in the primary oscillation frequency of the wake at saturation. In contrast, the onset of mode B occurs through a supercritical bifurcation with no frequency shift near threshold. Simulations of the three-dimensional wake for fixed Reynolds number and increasing spanwise dimension show that large systems evolve to a state of spatiotemporal chaos, and suggest that three-dimensionality in the wake leads to irregular states and fast transition to turbulence at Reynolds numbers just beyond the onset of the secondary instability. A key feature of these ‘turbulent’ states is the competition between self-excited, three-dimensional instability modes (global modes) in the mode A wavenumber band. These instability modes produce irregular spatiotemporal patterns and large-scale ‘spot-like’ disturbances in the wake during the breakdown of the regular mode A pattern. Simulations at higher Reynolds number show that long-wavelength interactions modulate fluctuating forces and cause variations in phase along the span of the cylinder that reduce the fluctuating amplitude of lift and drag. Results of both two-dimensional and three-dimensional simulations are presented for a range of Reynolds number from about 10 up to 1000

    The Confrontation of Federal Preemption and State Right-to-Work Laws

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    That Congress in enacting section 14(b) of the National Labor Relations Act authorized the states to adopt right-to-work laws banning forms of compulsory unionism otherwise permissable under federal law has never been seriously questioned. In this article the author discusses the more difficult problem of the extent to which section 14(b) does, or should, enable the states to deal with union-security issues irrespective of an elaborate federal regulatory scheme which touches identical or related subject matter

    Review of Videotape Presented at the 6th Annual Conference on Ethnic and Minority Studies: Alan Hertzberg, The Autobiography of Miss Jane Dubois

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    To say that The Autobiography of Miss Jane Dubois is an exciting new departure in the venerable art of autobiography does not do full justice to the work under review here. Nor is it sufficient to say that in giving us this study of human life, producer Alan Hertzberg proves that works of integrity and high purpose can be crafted by the video artist, holding out the promise that if it would, American television could lift itself from the slough of mediocrity in which it has ever wallowed. What makes this twelve- chapter study an unforgettable experience is Jane Dubois herself, the young black woman from New York City whose life we ”watch“ unfold over the course of three hours

    Charge storage in nanotubes: the case of a 2-1 electrolyte

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    We consider a 2-1 electrolyte in contact with a narrow nanotube, which only allows one-dimensional storage along the axis. The asymmetry does not allow an a priori definition of the potential of zero charge; instead, the natural reference is the electrode potential at which both ions have the same electrochemical potential; the value of the latter can serve as a measure of ionophilicity. Near this potential, ionophobic tubes are filled with a dilute gas, ionophilic tubes are filled with a one-dimensional solid containing about the same number of the divalent ions and the monovalent counterions, a structure that is stabilized by a strong screening of the Coulomb interaction by an induced counter charge on the walls of the tube. The filling of the tube by the application of an electrode potential exhibits a complicated pattern of interactions between the two kinds of ions.Comment: 7 pages, 6 figure

    Application of the SRISM approach to the study of the capacitance of the double layer of a high density primitive model electrolyte

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    In this study the Singlet Reference Interaction Site Model (SRISM) is employed to the study of the electrode charge dependence of the capacitance of a planar electric double layer using the primitive model of the double layer for a high density electrolyte that mimics an ionic liquid. The ions are represented by charged hard spheres and the electrode is a uniformly charged flat surface. The capacitance of this model fluid is calculated with the SRISM approach with closures based on the hypernetted chain (HNC) and Kovalenko-Hirata (KH) closures and compared with simulations. As long as the magnitude of the electrode charge is not too great, the HNC closure shows the most promise. The KH results are reasonably good for a high density electrolyte but are poor when applied at low densities.Comment: 6 pages, 2 figure

    Shuttle Program. Euler angles, quaternions, and transformation matrices working relationships

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    A brief mathematical development of the relationship between the Euler angles and the transformation matrix, the quaternion and the transformation matrix, and the Euler angles and the quaternion is presented. The analysis and equations presented apply directly to current space shuttle problems. The twelve three-axis Euler transformation matrices are given as functions of the Euler angles, the equations for the quaternion as a funtion of the Euler angles, and the Euler angles as a function of the transformation matrix elements
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