A Distinctive Large Breeding Population of Ringed Seals (Phoca hispida) Inhabiting the Baffin Bay Pack Ice

Aerial surveys in June and July, 1978 and 1979, documented an unexpectedly large population (at least 417,000) of ringed seals, some with pups, inhabiting the pack ice of Baffin Bay. Pack-ice seals are smaller than their fast-ice counterparts and have a different diet and gut parasite load. Age and productive data, although limited, indicate that the offshore seals are a normal breeding population. Pack-ice seals probably mix with fast-ice seals in coastal areas during the brief open-water season but morphological and ecological differences suggest that the populations are reproductively isolated. This study prompts reconsideration of the importance of offshore pack ice to ringed seals and, therefore, to the coastal hunting economy of Inuit in Greenland and Baffin Island.Key words: ringer seals, Baffin Bay, pack ice, distribution, population discreteness, managementDes inventaires aériens effectués en juin et juillet, 1978 et 1979, ont documenté une population importante d'au moins 417 000 phoques annelés, certains accompagnés de jeunes, habitant le pack de la baie Baffin. Les phoques du pack sont plus petits que ceux de la banquise côtière et ont un régime alimentaire et des parasites intestinaux différents. Des données sur l'âge et le reproduction, quoique limitées, indiquent que les phoques au large des côtes suivent un cycle de reproduction normal. Les phoques du pack se mêlent probablement à ceux de la banquise dans les régions côtières durant la brève saison d'eau libre mais les différences morphologiques et écologiques suggèrent que les populations se reproduisent peut-être indépendamment l'une de l'autre. La présente étude encourage une reconsidération de l'importance du pack chez les phoques annelés et ainsi, de son importance dans 1'économie côtière des Inuit chasseurs du Groenland et de l'île de Baffin.Mots clés: phoque annelés, baie Baffin, banquise, distribution, isolation reproductrice de la population, contrôle de la populatio

Type 0A 2D Black Hole Thermodynamics and the Deformed Matrix Model

Recently, it has been proposed that the deformed matrix model describes a two-dimensional type 0A extremal black hole. In this paper, the thermodynamics of 0A charged non-extremal black holes is investigated. We observe that the free energy of the deformed matrix model to leading order in 1/q can be seen to agree to that of the extremal black hole. We also speculate on how the deformed matrix model is able to describe the thermodynamics of non-extremal black holes.Comment: 12 page

Exotic torus manifolds and equivariant smooth structures on quasitoric manifolds

In 2006 Masuda and Suh asked if two compact non-singular toric varieties having isomorphic cohomology rings are homeomorphic. In the first part of this paper we discuss this question for topological generalizations of toric varieties, so-called torus manifolds. For example we show that there are homotopy equivalent torus manifolds which are not homeomorphic. Moreover, we characterize those groups which appear as the fundamental groups of locally standard torus manifolds. In the second part we give a classification of quasitoric manifolds and certain six-dimensional torus manifolds up to equivariant diffeomorphism. In the third part we enumerate the number of conjugacy classes of tori in the diffeomorphism group of torus manifolds. For torus manifolds of dimension greater than six there are always infinitely many conjugacy classes. We give examples which show that this does not hold for six-dimensional torus manifolds.Comment: 21 pages, 2 figures, results about quasitoric manifolds adde

Condensing Momentum Modes in 2-d 0A String Theory with Flux

We use a combination of conformal perturbation theory techniques and matrix model results to study the effects of perturbing by momentum modes two dimensional type 0A strings with non-vanishing Ramond-Ramond (RR) flux. In the limit of large RR flux (equivalently, mu=0) we find an explicit analytic form of the genus zero partition function in terms of the RR flux $q$ and the momentum modes coupling constant alpha. The analyticity of the partition function enables us to go beyond the perturbative regime and, for alpha>> q, obtain the partition function in a background corresponding to the momentum modes condensation. For momenta such that 0<p<2 we find no obstruction to condensing the momentum modes in the phase diagram of the partition function.Comment: 22 page

Integrable Deformations of c^=1\hat{c}=1 Strings in Flux Backgrounds

We study d=2 0A string theory perturbed by tachyon momentum modes in backgrounds with non-trivial tachyon condensate and Ramond-Ramond (RR) flux. In the matrix model description, we uncover a complexified Toda lattice hierarchy constrained by a pair of novel holomorphic string equations. We solve these constraints in the classical limit for general RR flux and tachyon condensate. Due to the non-holomorphic nature of the tachyon perturbations, the transcendental equations which we derive for the string susceptibility are manifestly non-holomorphic. We explore the phase structure and critical behavior of the theory.Comment: 39 pages, 4 figure

Smooth vortex precession in superfluid 4He

We have measured a precessing superfluid vortex line, stretched from a wire to the wall of a cylindrical cell. By contrast to previous experiments with a similar geometry, the motion along the wall is smooth. The key difference is probably that our wire is substantially off center. We verify several numerical predictions about the motion, including an asymmetry in the precession signature, the behavior of pinning events, and the temperature dependence of the precession.Comment: 8 pages, 8 figure

The Shapes of Dirichlet Defects

If the vacuum manifold of a field theory has the appropriate topological structure, the theory admits topological structures analogous to the D-branes of string theory, in which defects of one dimension terminate on other defects of higher dimension. The shapes of such defects are analyzed numerically, with special attention paid to the intersection regions. Walls (co-dimension 1 branes) terminating on other walls, global strings (co-dimension 2 branes) and local strings (including gauge fields) terminating on walls are all considered. Connections to supersymmetric field theories, string theory and condensed matter systems are pointed out.Comment: 24 pages, RevTeX, 21 eps figure

Collisional Velocities and Rates in Resonant Planetesimal Belts

We consider a belt of small bodies around a star, captured in one of the external or 1:1 mean-motion resonances with a massive perturber. The objects in the belt collide with each other. Combining methods of celestial mechanics and statistical physics, we calculate mean collisional velocities and collisional rates, averaged over the belt. The results are compared to collisional velocities and rates in a similar, but non-resonant belt, as predicted by the particle-in-a-box method. It is found that the effect of the resonant lock on the velocities is rather small, while on the rates more substantial. The collisional rates between objects in an external resonance are by about a factor of two higher than those in a similar belt of objects not locked in a resonance. For Trojans under the same conditions, the collisional rates may be enhanced by up to an order of magnitude. Our results imply, in particular, shorter collisional lifetimes of resonant Kuiper belt objects in the solar system and higher efficiency of dust production by resonant planetesimals in debris disks around other stars.Comment: 31 pages, 11 figures (some of them heavily compressed to fit into arxiv-maximum filesize), accepted for publication at "Celestial Mechanics and Dynamical Astronomy

Tunelling with a Negative Cosmological Constant

The point of this paper is see what light new results in hyperbolic geometry may throw on gravitational entropy and whether gravitational entropy is relevant for the quantum origin of the univeres. We introduce some new gravitational instantons which mediate the birth from nothing of closed universes containing wormholes and suggest that they may contribute to the density matrix of the universe. We also discuss the connection between their gravitational action and the topological and volumetric entropies introduced in hyperbolic geometry. These coincide for hyperbolic 4-manifolds, and increase with increasing topological complexity of the four manifold. We raise the questions of whether the action also increases with the topological complexity of the initial 3-geometry, measured either by its three volume or its Matveev complexity. We point out, in distinction to the non-supergravity case, that universes with domains of negative cosmological constant separated by supergravity domain walls cannot be born from nothing. Finally we point out that our wormholes provide examples of the type of Perpetual Motion machines envisaged by Frolov and Novikov.Comment: 36 pages, plain TE