20,891 research outputs found

    Program for the 18th Annual John F. Sonnett Memorial Lecture Series: Bill of Rights

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    Program for the 18th Annual John F. Sonnett Memorial Lecture Series: Bill of Rights by Judge John J. Gibbons, Chief Judge of the U.S. Court of Appeals for the Third Circuit (1987-1990).https://ir.lawnet.fordham.edu/events_programs_sonnett_miscellaneous/1004/thumbnail.jp

    A genus six cyclic tetragonal reduction of the Benney equations

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    A reduction of Benney’s equations is constructed corresponding to Schwartz–Christoffel maps associated with a family of genus six cyclic tetragonal curves. The mapping function, a second kind Abelian integral on the associated Riemann surface, is constructed explicitly as a rational expression in derivatives of the Kleinian σ-function of the curve

    Complex Numbers, Quantum Mechanics and the Beginning of Time

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    A basic problem in quantizing a field in curved space is the decomposition of the classical modes in positive and negative frequency. The decomposition is equivalent to a choice of a complex structure in the space of classical solutions. In our construction the real tunneling geometries provide the link between the this complex structure and analytic properties of the classical solutions in a Riemannian section of space. This is related to the Osterwalder- Schrader approach to Euclidean field theory.Comment: 27 pages LATEX, UCSBTH-93-0

    Localized Activation of Bending in Proximal, Medial and Distal Regions of Sea-Urchin Sperm Flagella

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    Spermatozoa from the sea urchin, Colobocentrotus atratus, were partially demembranated by extraction with solutions containing Triton X-100 at a concentration which was insufficient to solubilize the membranes completely. The resulting suspension was a mixture containing some spermatozoa in which a proximal, medial, or distal portion of the flagellum was membrane-covered, while the remaining portion was naked axoneme. In reactivating solutions containing 12 µM ATP, only the naked portions of the flagellum became motile. In reactivating solutions containing 0.8 mM ADP, the membrane-covered regions became motile and beat at 6-10 beats/s, while the naked regions remained immobile, or beat very slowly at about 0.3 beat/s. Activation of membrane-covered regions in ADP solutions probably results from the membrane restricting the diffusion of ATP which is formed from ADP by the axonemal adenylate kinase. The results indicate that any region of the flagellum has the capacity for autonomous beating, and that special properties of the basal end of the flagellum are not required for bend initiation. However, the beating of different regions of the flagellum is not completely independent, for in a fair number of spermatozoa the beating of the distal, membrane-covered region in 0.8 mM ADP was intermittent, and was turned on and off in phase with the much slower bending cycle in the proximal region of naked axoneme

    WHAT IS A HERPETOLOGIST AND HOW CAN I BECOME ONE?

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    The following is the first in the JNAH series in which we address a variety of topics on herpetology based on essays from our upcoming book “How to Be a Herpetologist,”. We will also answer frequently asked questions we and other professional herpetologists receive from students, colleagues, and the general public about herpetology as a career or an avocation

    Geodesic flows on semidirect-product Lie groups: geometry of singular measure-valued solutions

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    The EPDiff equation (or dispersionless Camassa-Holm equation in 1D) is a well known example of geodesic motion on the Diff group of smooth invertible maps (diffeomorphisms). Its recent two-component extension governs geodesic motion on the semidirect product DiffF{\rm Diff}\circledS{\cal F}, where F\mathcal{F} denotes the space of scalar functions. This paper generalizes the second construction to consider geodesic motion on Diffg{\rm Diff} \circledS\mathfrak{g}, where g\mathfrak{g} denotes the space of scalar functions that take values on a certain Lie algebra (for example, g=Fso(3)\mathfrak{g}=\mathcal{F}\otimes\mathfrak{so}(3)). Measure-valued delta-like solutions are shown to be momentum maps possessing a dual pair structure, thereby extending previous results for the EPDiff equation. The collective Hamiltonians are shown to fit into the Kaluza-Klein theory of particles in a Yang-Mills field and these formulations are shown to apply also at the continuum PDE level. In the continuum description, the Kaluza-Klein approach produces the Kelvin circulation theorem.Comment: 22 pages, 2 figures. Submitted to Proc. R. Soc.

    The Physics of 2-d Stringy Spacetimes

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    We examine the two-dimensional spacetimes that emerge from string theory. We find all the solutions with no tachyons, and show that the only non-trivial solution is the black hole spacetime. We examine the role of duality in this picture. We then explore the thermodynamics of these solutions which is complicated by the fact that only in two spacetime dimensions is it impossible to redefine the dilaton field in terms of a canonical scalar field. Finally, we extend our analysis to the heterotic string, and briefly comment on exact, as opposed to perturbative, solutions

    Branes as BIons

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    A BIon may be defined as a finite energy solution of a non-linear field theory with distributional sources. By contrast a soliton is usually defined to have no sources. I show how harmonic coordinates map the exteriors of the topologically and causally non-trivial spacetimes of extreme p-branes to BIonic solutions of the Einstein equations in a topologically trivial spacetime in which the combined gravitational and matter energy momentum is located on distributional sources. As a consequence the tension of BPS p-branes is classically unrenormalized. The result holds equally for spacetimes with singularities and for those, like the M-5-brane, which are everywhere singularity free.Comment: Latex, 9 pages, no figure

    Moduli, Scalar Charges, and the First Law of Black Hole Thermodynamics

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    We show that under variation of moduli fields ϕ\phi the first law of black hole thermodynamics becomes dM=κdA8π+ΩdJ+ψdq+χdpΣdϕdM = {\kappa dA\over 8\pi} + \Omega dJ + \psi dq + \chi dp - \Sigma d\phi, where Σ\Sigma are the scalar charges. We also show that the ADM mass is extremized at fixed AA, JJ, (p,q)(p,q) when the moduli fields take the fixed value ϕfix(p,q)\phi_{\rm fix}(p,q) which depend only on electric and magnetic charges. It follows that the least mass of any black hole with fixed conserved electric and magnetic charges is given by the mass of the double-extreme black hole with these charges. Our work allows us to interpret the previously established result that for all extreme black holes the moduli fields at the horizon take a value ϕ=ϕfix(p,q)\phi= \phi_{\rm fix}(p,q) depending only on the electric and magnetic conserved charges: ϕfix(p,q) \phi_{\rm fix}(p,q) is such that the scalar charges Σ(ϕfix,(p,q))=0\Sigma ( \phi_{\rm fix}, (p,q))=0.Comment: 3 pages, no figures, more detailed versio

    Sigma, tau and Abelian functions of algebraic curves

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    We compare and contrast three different methods for the construction of the differential relations satisfied by the fundamental Abelian functions associated with an algebraic curve. We realize these Abelian functions as logarithmic derivatives of the associated sigma function. In two of the methods, the use of the tau function, expressed in terms of the sigma function, is central to the construction of differential relations between the Abelian functions.Comment: 25 page
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