54,362 research outputs found

    Mesoscale variability in intact and ghost colonies of Phaeocystis antarctica in the Ross Sea : distribution and abundance

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    © The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Marine Systems 166 (2017): 97-107, doi:10.1016/j.jmarsys.2016.05.007.Phaeocystis, a genus with a cosmopolitan distribution and a polymorphic life cycle, was observed during summer in the Ross Sea, Antarctica, where large blooms of this haptophyte regularly occur. The mesoscale vertical and horizontal distributions of colonies of P. antarctica were assessed using a towed Video Plankton Recorder (VPR). The mean size of colonies was 1.20 mm, and mean abundances within the three VPR surveys were 4.86, 1.96, and 11.5 mL-1. In addition to the typical spherical, transparent colonies, the VPR quantified an optically dissimilar form of colony that had a distinctive translucent appearance. It also measured the abundance of collapsed colonies, similar to those observed previously from cultures and mesocosms, which we called “ghost colonies”. The translucent colonial form had a different distribution than the more common colonial form, and at times was more abundant. Relative to intact colonies, the ghost colonies occurred less frequently, with mean abundances in the three surveys being 0.01, 0.08, and 0.0004 mL-1. Ghost colonies generally were found below the euphotic zone, where they often were in greater abundance than intact colonies. However, the relationship of ghost colonies to intact P. antarctica colonies was not direct or consistent, suggesting that the formation of ghost colonies from living colonies and their appearance within the water column were not tightly coupled. Given their relative scarcity and low carbon content, it is unlikely that ghost colonies contribute substantially to vertical flux; however, it is possible that we did not sample periods of major flux events, and as a result minimized the importance of ghost colonies to vertical flux. They do, however, represent a poorly documented feature of polar haptophyte life cycles.This research was supported by grants from the National Science Foundation (ANT-0944254 and ANT-0944165). HMS and EEP acknowledge support of the Gordon and Betty Moore Foundation (Grant #2649) for image informatics development.2018-06-0

    Let's Twist Again: N=2 Super Yang Mills Theory Coupled To Matter

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    We give the twisted version of N=2 Super Yang Mills theory coupled to matter, including quantum fields, supersymmetry transformations, action and algebraic structure. We show that the whole action, coupled to matter, can be written as the variation of a nilpotent operator, modulo field equations. An extended Slavnov-Taylor identity, collecting gauge symmetry and supersymmetry, is written, which allows to define the web of algebraic constraints, in view of the algebraic renormalization and of the extension of the non-renormalization theorems holding for N=2 SYM theory without matter.Comment: 28 pages, final version to be published on CQ

    The Feeding Behaviour Of The Ghost Ants, Tapinoma Melanocephalum (Fabricius) And Tapinoma Indicum (Forel) (Hymenoptera: Formicidae)

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    Thesis ini bertumpu kepada perilaku pemakanan dua spesies semut mayat, Tapinoma melanocephalum (Fabricius) dan Tapinoma indicum (Forel). This thesis focuses on the feeding behaviour of two species of the ghost ant, namely Tapinoma melanocephalum (Fabricius) and Tapinoma indicum (Forel)

    Physical unitarity for a massive Yang-Mills theory without the Higgs field: (I) A perturbative treatment

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    In a series of papers, we examine the physical unitarity in a massive Yang-Mills theory without the Higgs field in which the color gauge symmetry is not spontaneously broken and kept intact. For this purpose, we use a new framework proposed in the previous paper Kondo [arXiv:1208.3521] based on a nonperturbative construction of a non-Abelian field describing a massive spin-one vector boson field, which enables us to perform the perturbative and nonperturbative studies on the physical unitarity. In this paper, we present a new perturbative treatment for the physical unitarity after giving the general properties of the massive Yang-Mills theory. Then we reproduce the violation of physical unitarity in a transparent way. This paper is a preliminary work to the subsequent papers in which we present a nonperturbative framework to propose a possible scenario of restoring the physical unitarity in the Curci-Ferrari model.Comment: 17 pages, 11 figures, references updated, a version published in Phys.Rev.D. arXiv admin note: substantial text overlap with arXiv:1208.352

    Higher covariant derivative regulators and non-multiplicative renormalization

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    The renormalization algorithm based on regularization methods with two regulators is analyzed by means of explicit computations. We show in particular that regularization by higher covariant derivative terms can be complemented with dimensional regularization to obtain a consistent renormalized 4-dimensional Yang-Mills theory at the one-loop level. This shows that hybrid regularization methods can be applied not only to finite theories, like \eg\ Chern-Simons, but also to divergent theories.Comment: 12 pages, phyzzx, no figure

    Super-Weyl Invariant 2D Supergravity, Anomaly and WZ Action

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    We present a candidate of anomaly and Wess Zumino action of the two dimensional supergravity coupling with matters in a super-Weyl invariant regularization. It is a generalization of the Weyl and the area preserving \Diff invariant formulation of two dimensional gravity theory.Comment: 9 pages, Late

    Non-perturbative BRST invariance and what it might be good for

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    We construct a local, gauge-fixed, lattice Yang-Mills theory with an exact BRST invariance, and with the same perturbative expansion as the standard Yang-Mills theory. The ghost sector, and some of its BRST transformation rules, are modified to get around Neuberger's theorem. A special term is introduced in the action to regularize the Gribov horizons, and the limit where the regulator is removed is discussed. We conclude with a few comments on what might be the physical significance of this theory. We speculate that there may exist new strong-interaction phases apart from the anticipated confinement phase.Comment: 3 pages, Lattice2002(theoretical), For additional technical details see ref.

    Topological Yang-Mills Theories and Their Observables: a Superspace Approach

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    Witten's observables of topological Yang-Mills theory, defined as classes of an equivariant cohomology, are reobtained as the BRST cohomology classes of a superspace version of the theory.Comment: 8 pages, Latex - Talk given by O.P. at the 2nd Londrina International Winter School Mathematical Methods in Physics, August 2002, Londrina, Brazi

    On the BFFT quantization of first order systems

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    By using the field-antifield formalism, we show that the method of Batalin, Fradkin, Fradkina and Tyutin to convert Hamiltonian systems submitted to second class constraints introduces compensating fields which do not belong to the BRST cohomology at ghost number one. This assures that the gauge symmetries which arise from the BFFT procedure are not obstructed at quantum level. An example where massive electrodynamics is coupled to chiral fermions is considered. We solve the quantum master equation for the model and show that the respective counterterm has a decisive role in extracting anomalous expectation values associated with the divergence of the Noether chiral current.Comment: 18 pages, LaTeX, no figures, to appear in Journal of Mathematical Physic
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