721 research outputs found

    Growth of the Northern Fur Seal Colony on Bogoslof Island, Alaska

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    Northern fur seal, Callorhinus ursinus, pups were first observed on Bogoslof Island, southeast Bering Sea, in 1980. By 1988 the population had grown at a rate of 57%/yr to over 400 individuals, including 80+ pups, 159 adult females, 22 territorial males, and 188 subadult males. Some animals originated from rookeries of the Commander Islands, whereas others are probably from the Pribilof Islands. In 1983 and 1985 over 50% of the females were estimated to be >6 years of age, based on vibrissae color. The rookery is in the same location where solitary male fur seals were seen in 1976 and 1979 and is adjacent to a large northern sea lion rookery.Key words: Bogoslof Island, northern fur seal, Callorhinus ursinus, northern sea lion, breeding colonyMots clés: île Bogoslof, otarie à fourrure nordique, Callorhinus ursinus, lion de mer nordique, colonie reproductric

    Gray Whales (Eschrichtius robustus) in the Western Chukchi and East Siberian Seas

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    During joint Soviet-American shipboard surveys in autumn 1979 and 1980, numerous sightings of gray whales (Eschrichtius robustus) were made in the western Chukchi and East Siberian seas. Gray whales were observed well offshore in ice-free water in 1979, but near the Chukotka coast in 1980. During the 1980 survey, gray whales were observed further west than previously recorded, with three animals seen at 174 08 E longitude, well into the East Siberian Sea. Based on indirect evidence of gray whale behavior and typical prey organisms identified in bottom samples, we assume gray whales are feeding in the western Chukchi Sea during summer and fall. Movement of these animals further west into the East Siberian Sea may occur regularly when ice conditions permit, but it may also be a response to increasing population size over the past several decades, and gray whales may be reoccupying habitat unused during periods of low population caused by commercial whaling.Key words: gray whale, Eschrichtius robustus, cetacean, Chukchi Sea, East Siberian SeaMots clés: baleine grise de Californie, Eschrichtius robustus, cétacé, mer Tchouktche, mer de Sibérie Oriental

    Tumor-homing cytotoxic human induced neural stem cells for cancer therapy

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    Engineered neural stem cells (NSCs) are a promising approach to treating glioblastoma (GBM). The ideal NSC drug carrier for clinical use should be easily isolated and autologous to avoid immune rejection. We transdifferentiated (TD) human fibroblasts into tumor-homing early-stage induced NSCs (h-iNSCTE), engineered them to express optical reporters and different therapeutic gene products, and assessed the tumor-homing migration and therapeutic efficacy of cytotoxic h-iNSCTE in patient-derived GBM models of surgical and nonsurgical disease. Molecular and functional analysis revealed that our single-factor SOX2 TD strategy converted human skin fibroblasts into h-iNSCTE that were nestin+ and expressed pathways associated with tumor-homing migration in 4 days. Time-lapse motion analysis showed that h-iNSCTE rapidly migrated to human GBM cells and penetrated human GBM spheroids, a process inhibited by blockade of CXCR4. Serial imaging showed that h-iNSCTE delivery of the proapoptotic agent tumor necrosis factor-A-related apoptosis-inducing ligand (TRAIL) reduced the size of solid human GBM xenografts 250-fold in 3 weeks and prolonged median survival from 22 to 49 days. Additionally, h-iNSCTE thymidine kinase/ganciclovir enzyme/prodrug therapy (h-iNSCTE-TK) reduced the size of patient-derived GBM xenografts 20-fold and extended survival from 32 to 62 days. Mimicking clinical NSC therapy, h-iNSCTE-TK therapy delivered into the postoperative surgical resection cavity delayed the regrowth of residual GBMs threefold and prolonged survival from 46 to 60 days. These results suggest that TD of human skin into h-iNSCTE is a platform for creating tumor-homing cytotoxic cell therapies for cancer, where the potential to avoid carrier rejection could maximize treatment durability in human trials

    Temporal, Situational and Interactional Features of Women’s Violent Conflicts

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    This article examines contextual and situational influences on the processural development of women\u27s violent conflicts. Through close analysis of 3 women\u27s accounts of their disputes and associated violent behaviours, we provide a rich description of how such events evolved over time and how the interviewees managed this process. Drawing upon both criminological and feminist theories, our analysis highlights existing gaps in the literature, providing an exploratory discussion of the interaction of gender with situational elements and the production of assaultive events

    A dimensionally continued Poisson summation formula

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    We generalize the standard Poisson summation formula for lattices so that it operates on the level of theta series, allowing us to introduce noninteger dimension parameters (using the dimensionally continued Fourier transform). When combined with one of the proofs of the Jacobi imaginary transformation of theta functions that does not use the Poisson summation formula, our proof of this generalized Poisson summation formula also provides a new proof of the standard Poisson summation formula for dimensions greater than 2 (with appropriate hypotheses on the function being summed). In general, our methods work to establish the (Voronoi) summation formulae associated with functions satisfying (modular) transformations of the Jacobi imaginary type by means of a density argument (as opposed to the usual Mellin transform approach). In particular, we construct a family of generalized theta series from Jacobi theta functions from which these summation formulae can be obtained. This family contains several families of modular forms, but is significantly more general than any of them. Our result also relaxes several of the hypotheses in the standard statements of these summation formulae. The density result we prove for Gaussians in the Schwartz space may be of independent interest.Comment: 12 pages, version accepted by JFAA, with various additions and improvement

    Evidence for a three-nucleon-force effect in proton-deuteron elastic scattering

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    Developments in spin-polarized internal targets for storage rings have permitted measurements of 197 MeV polarized protons scattering from vector polarized deuterons. This work presents measurements of the polarization observables A_y, iT_11, and C_y,y in proton-deuteron elastic scattering. When compared to calculations with and without three-nucleon forces, the measurements indicate that three-nucleon forces make a significant contribution to the observables. This work indicates that three-body forces derived from static nuclear properties appear to be crucial to the description of dynamical properties.Comment: 8 pages 2 figures Latex, submitted to Phys. Rev. Letter

    On the Circular Orbit Approximation for Binary Compact Objects In General Relativity

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    One often-used approximation in the study of binary compact objects (i.e., black holes and neutron stars) in general relativity is the instantaneously circular orbit assumption. This approximation has been used extensively, from the calculation of innermost circular orbits to the construction of initial data for numerical relativity calculations. While this assumption is inconsistent with generic general relativistic astrophysical inspiral phenomena where the dissipative effects of gravitational radiation cause the separation of the compact objects to decrease in time, it is usually argued that the timescale of this dissipation is much longer than the orbital timescale so that the approximation of circular orbits is valid. Here, we quantitatively analyze this approximation using a post-Newtonian approach that includes terms up to order ({Gm/(rc^2)})^{9/2} for non-spinning particles. By calculating the evolution of equal mass black hole / black hole binary systems starting with circular orbit configurations and comparing them to the more astrophysically relevant quasicircular solutions, we show that a minimum initial separation corresponding to at least 6 (3.5) orbits before plunge is required in order to bound the detection event loss rate in gravitational wave detectors to < 5% (20%). In addition, we show that the detection event loss rate is > 95% for a range of initial separations that include all modern calculations of the innermost circular orbit (ICO).Comment: 10 pages, 12 figures, revtex

    Improved description of charged Higgs boson production at hadron colliders

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    We present a new method for matching the two twin-processes gb->H+/-t and gg->H+/-tb in Monte Carlo event generators. The matching is done by defining a double-counting term, which is used to generate events that are subtracted from the sum of these two twin-processes. In this way we get a smooth transition between the collinear region of phase space, which is best described by gb->H+/-t, and the hard region, which requires the use of the gg->H+/-tb process. The resulting differential distributions show large differences compared to both the gb-> H+/-t and gg->H+/-tb processes illustrating the necessity to use matching when tagging the accompanying b-jet.Comment: 21 pages, 9 figures. Revised with updated discussion and reference

    Transformation elastodynamics and active exterior acoustic cloaking

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    This chapter consists of three parts. In the first part we recall the elastodynamic equations under coordinate transformations. The idea is to use coordinate transformations to manipulate waves propagating in an elastic material. Then we study the effect of transformations on a mass-spring network model. The transformed networks can be realized with "torque springs", which are introduced here and are springs with a force proportional to the displacement in a direction other than the direction of the spring terminals. Possible homogenizations of the transformed networks are presented, with potential applications to cloaking. In the second and third parts we present cloaking methods that are based on cancelling an incident field using active devices which are exterior to the cloaked region and that do not generate significant fields far away from the devices. In the second part, the exterior cloaking problem for the Laplace equation is reformulated as the problem of polynomial approximation of analytic functions. An explicit solution is given that allows to cloak larger objects at a fixed distance from the cloaking device, compared to previous explicit solutions. In the third part we consider the active exterior cloaking problem for the Helmholtz equation in 3D. Our method uses the Green's formula and an addition theorem for spherical outgoing waves to design devices that mimic the effect of the single and double layer potentials in Green's formula.Comment: Submitted as a chapter for the volume "Acoustic metamaterials: Negative refraction, imaging, lensing and cloaking", Craster and Guenneau ed., Springe

    Isospin-Violating Meson-Nucleon Vertices as an Alternate Mechanism of Charge-Symmetry Breaking

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    We compute isospin-violating meson-nucleon coupling constants and their consequent charge-symmetry-breaking nucleon-nucleon potentials. The couplings result from evaluating matrix elements of quark currents between nucleon states in a nonrelativistic constituent quark model; the isospin violations arise from the difference in the up and down constituent quark masses. We find, in particular, that isospin violation in the omega-meson--nucleon vertex dominates the class IV CSB potential obtained from these considerations. We evaluate the resulting spin-singlet--triplet mixing angles, the quantities germane to the difference of neutron and proton analyzing powers measured in elastic n⃗−p⃗\vec{n}-\vec{p} scattering, and find them commensurate to those computed originally using the on-shell value of the ρ\rho-ω\omega mixing amplitude. The use of the on-shell ρ\rho-ω\omega mixing amplitude at q2=0q^2=0 has been called into question; rather, the amplitude is zero in a wide class of models. Our model possesses no contribution from ρ\rho-ω\omega mixing at q2=0q^2=0, and we find that omega-meson exchange suffices to explain the measured n−pn-p analyzing power difference~at~183 MeV.Comment: 20 pages, revtex, 3 uuencoded PostScript figure
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