185 research outputs found

    High-energy gamma-ray emission from the inner jet of LS I+61 303: the hadronic contribution revisited

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    LS I+61 303 has been detected by the Cherenkov telescope MAGIC at very high energies, presenting a variable flux along the orbital motion with a maximum clearly separated from the periastron passage. In the light of the new observational constraints, we revisit the discussion of the production of high-energy gamma rays from particle interactions in the inner jet of this system. The hadronic contribution could represent a major fraction of the TeV emission detected from this source. The spectral energy distribution resulting from p-p interactions is recalculated. Opacity effects introduced by the photon fields of the primary star and the stellar decretion disk are shown to be essential in shaping the high-energy gamma-ray light curve at energies close to 200 GeV. We also present results of Monte Carlo simulations of the electromagnetic cascades developed very close to the periastron passage. We conclude that a hadronic microquasar model for the gamma-ray emission in LS I +61 303 can reproduce the main features of its observed high-energy gamma-ray flux.Comment: 6 pages. Sligth improvements made. Accepted version by Astrophysics and Space Scienc

    A common terminology for the external anatomy of centipedes (Chilopoda)

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    A common terminology for the external morphological characters of centipedes (Chilopoda) is proposed. Terms are selected from the alternatives used in the English literature, preferring those most frequently used or those that have been introduced explicitly. A total of 330 terms are defi ned and illustrated, and another ca. 500 alternatives are listed.Facultad de Ciencias Naturales y Muse

    Reproducing Kernels of Generalized Sobolev Spaces via a Green Function Approach with Distributional Operators

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    In this paper we introduce a generalized Sobolev space by defining a semi-inner product formulated in terms of a vector distributional operator P\mathbf{P} consisting of finitely or countably many distributional operators PnP_n, which are defined on the dual space of the Schwartz space. The types of operators we consider include not only differential operators, but also more general distributional operators such as pseudo-differential operators. We deduce that a certain appropriate full-space Green function GG with respect to L:=PTPL:=\mathbf{P}^{\ast T}\mathbf{P} now becomes a conditionally positive definite function. In order to support this claim we ensure that the distributional adjoint operator P\mathbf{P}^{\ast} of P\mathbf{P} is well-defined in the distributional sense. Under sufficient conditions, the native space (reproducing-kernel Hilbert space) associated with the Green function GG can be isometrically embedded into or even be isometrically equivalent to a generalized Sobolev space. As an application, we take linear combinations of translates of the Green function with possibly added polynomial terms and construct a multivariate minimum-norm interpolant sf,Xs_{f,X} to data values sampled from an unknown generalized Sobolev function ff at data sites located in some set XRdX \subset \mathbb{R}^d. We provide several examples, such as Mat\'ern kernels or Gaussian kernels, that illustrate how many reproducing-kernel Hilbert spaces of well-known reproducing kernels are isometrically equivalent to a generalized Sobolev space. These examples further illustrate how we can rescale the Sobolev spaces by the vector distributional operator P\mathbf{P}. Introducing the notion of scale as part of the definition of a generalized Sobolev space may help us to choose the "best" kernel function for kernel-based approximation methods.Comment: Update version of the publish at Num. Math. closed to Qi Ye's Ph.D. thesis (\url{http://mypages.iit.edu/~qye3/PhdThesis-2012-AMS-QiYe-IIT.pdf}

    Towards a population of HMXB/NS microquasars as counterparts of low-latitude unidentified EGRET sources

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    The discovery of the microquasar LS 5039 well within the 95% conficence contour of the Unidentified EGRET Source (UES) 3EG J1824-1514 was a major step towards the possible association between microquasars (MQs) and UESs. The recent discovery of precessing relativistic radio jets in LS I +61 303, a source associated for long time with 2CG 135+01 and with the UES 3EG J0241+6103, has given further support to this idea. Finally, the very recently proposed association between the microquasar candidate AX J1639.0-4642 and the UES 3EG J1639-4702 points towards a population of High Mass X-ray Binary (HMXB)/Neutron Star (NS) microquasars as counterparts of low-latitude unidentified EGRET sources.Comment: 12 pages, 7 figures. Proceedings of the Conference "The Multiwavelength Approach to Unidentified Gamma-ray Sources", to appear in the journal Astrophysics and Space Scienc

    Checklist of the Lepidoptera of British Columbia, Canada

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    This list documents 2832 Lepidoptera species reported for the province of British Columbia, Canada. It is based on examination of the major public insect collections in the province and the Canadian National Collection of Insects, Arachnids and Nematodes, Ottawa, Ontario. Records from relevant literature sources and online databases have also been examined and reliable ones have been included. The entry for each species includes the scientific name, the author and year of publication of the original description, and occurrence status. Taxonomic, distributional and biological notes are provided for selected species, and 134 species are flagged as introduced from outside North America. An additional 27 species which probably occur in British Columbia are included in the list. A list of 322 species erroneously reported from British Columbia in previous works is provided. Introductory sections provide an overview of the order Lepidoptera, review the province’s ecozones, and discuss the history of lepidopterology in British Columbia and its current state of knowledge. Each of the 70 families occurring in the province is briefly reviewed, along with information on its distinguishing features, general appearance and biology and diversity. An index of higher taxonomic names, genera, species, and common names is included

    Baxter Q-operator and Separation of Variables for the open SL(2,R) spin chain

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    We construct the Baxter Q-operator and the representation of the Separated Variables (SoV) for the homogeneous open SL(2,R) spin chain. Applying the diagrammatical approach, we calculate Sklyanin's integration measure in the separated variables and obtain the solution to the spectral problem for the model in terms of the eigenvalues of the Q-operator. We show that the transition kernel to the SoV representation is factorized into the product of certain operators each depending on a single separated variable. As a consequence, it has a universal pyramid-like form that has been already observed for various quantum integrable models such as periodic Toda chain, closed SL(2,R) and SL(2,C) spin chains.Comment: 29 pages, 9 figures, Latex styl

    A common terminology for the external anatomy of centipedes (Chilopoda)

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    A common terminology for the external morphological characters of centipedes (Chilopoda) is proposed. Terms are selected from the alternatives used in the English literature, preferring those most frequently used or those that have been introduced explicitly. A total of 330 terms are defi ned and illustrated, and another ca. 500 alternatives are listed.Facultad de Ciencias Naturales y Muse

    Discovering Usability: Comparing Two Discovery Systems at One Academic Library

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    In the spring of 2013, the University Library at the University of Illinois at Chicago was in the unique position of having access to two discovery systems, Summon and WorldCat Local, at the same time. When tasked with choosing between the two systems, librarians undertook a usability study of Summon and WorldCat Local. The goal of this study was two-fold: to test the ease-of-use of each discovery system with an eye toward identifying one tool to retain for the longer term, and to learn about the search behaviors of different types of user groups. Eighteen subjects, consisting of undergraduate students, graduate students and faculty, participated in the study. Participants performed usability tasks using each tool and answered pre-task and post-task questions. While there was no clear preference among study participants for either discovery layer, individual groups did express preferences. Faculty, for example, preferred Summon to WorldCat Local at a rate of five to one. The study findings are explored in detail through an examination of the three major data sets produced by the usability test instrument: results derived from tasks performed by participants as part of the study; themes and trends identified by the investigators within the recorded participant tests; and discovery tool preferences as determined from pre-task and post-task questionnaires administered to study participants. This study has implications for librarians engaged in information literacy instruction; those considering implementing discovery tools, as well as for librarians currently using Summon or WorldCat Local at their libraries

    Categorizing Different Approaches to the Cosmological Constant Problem

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    We have found that proposals addressing the old cosmological constant problem come in various categories. The aim of this paper is to identify as many different, credible mechanisms as possible and to provide them with a code for future reference. We find that they all can be classified into five different schemes of which we indicate the advantages and drawbacks. Besides, we add a new approach based on a symmetry principle mapping real to imaginary spacetime.Comment: updated version, accepted for publicatio

    Domain wall generation by fermion self-interaction and light particles

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    A possible explanation for the appearance of light fermions and Higgs bosons on the four-dimensional domain wall is proposed. The mechanism of light particle trapping is accounted for by a strong self-interaction of five-dimensional pre-quarks. We obtain the low-energy effective action which exhibits the invariance under the so called \tau-symmetry. Then we find a set of vacuum solutions which break that symmetry and the five-dimensional translational invariance. One type of those vacuum solutions gives rise to the domain wall formation with consequent trapping of light massive fermions and Higgs-like bosons as well as massless sterile scalars, the so-called branons. The induced relations between low-energy couplings for Yukawa and scalar field interactions allow to make certain predictions for light particle masses and couplings themselves, which might provide a signature of the higher dimensional origin of particle physics at future experiments. The manifest translational symmetry breaking, eventually due to some gravitational and/or matter fields in five dimensions, is effectively realized with the help of background scalar defects. As a result the branons acquire masses, whereas the ratio of Higgs and fermion (presumably top-quark) masses can be reduced towards the values compatible with the present-day phenomenology. Since the branons do not couple to fermions and the Higgs bosons do not decay into branons, the latter ones are essentially sterile and stable, what makes them the natural candidates for the dark matter in the Universe.Comment: 34 pages, 2 figures, JHEP style,few important refs. adde
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