340 research outputs found

    Sums of commutators in pure C*-algebras

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    A segmented and clawed male foreleg in a newly described genus and species of eumaeine butterfly (Lepidoptera: Lycaenidae)

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    Grishinata Robbins and Busby, new genus (Lepidoptera: Lycaenidae: Eumaeini), possesses a five-segmented foretarsus with a clawed pretarsus, a trait that differentiates it from all eumaeine genera except Theclopsis Godman and Salvin. Grishinata penny Busby, Hall, and Robbins, new species, differs from all species of Theclopsis (and most Eumaeini) in lacking male secondary sexual organs on the wings or in the abdomen. It is recorded from the eastern slope of the Andes in Ecuador and Peru. We cannot place Grishinata penny in an existing Eumaeini genus based upon its wing pattern, male foreleg structure, lack of male second­ary sexual organs, and male genitalic morphology. We propose names for the genus and species to document its leg morphology and to provide a name for a genome sequencing project, which will allow us to place the genus in the eumaeine Linnaean hierarchy. There are two morphological types of male forelegs in the lepidopteran butterfly family Lycaenidae, each of which is functionally and structurally different from male forelegs in other diurnal butterfly families. The first male foreleg type is superficially similar to that of Nymphalidae and Riodinidae in that the tarsus is unsegmented, lacks a pretarsus, and is not used to groom the antennae (Robbins 1988, 1990). It differs functionally from these families in that it is used for walking. It differs morphologically in that it possesses tarsal alpha and beta trichoid sensilla (terminology from Chun and Schoonhoven 1973), which are lacking in Nymphalidae and Riodinidae with few exceptions (Robbins 1988). This male foreleg type occurs in more than 98% of lycaenid species (Mattoni and Fiedler 1991). The second lycaenid male foreleg type is superficially similar to that of Hesperiidae, Papilionidae, and Pieridae in that the foretarsus is segmented with a clawed pretarsus. It differs functionally from these families in that it is not used to groom the antennae (Jander 1966; Robbins 1990). It differs morphologically in that it lacks the tibial epiphysis of Hesperiidae and Papilionidae or the vestigial remnant of an epiphysis that occurs in some Pieridae (Robbins 1990). Within Eumaeini, this male foreleg type is restricted to some species of Theclopsis Godman and Salvin, 1887 (Godman and Salvin 1887; Robbins 2004). We discovered a species (Fig. 1) belonging to the Eumaeini with a male foreleg that has a clawed pretarsus and a five-segmented tarsus (Fig. 2), but the male genitalia, secondary sexual characters, and wing pattern (Fig. 1, 3) are dissimilar from those of Theclopsis. The males lack secondary sexual organs on the wings or in the abdomen (Fig. 1, 3), which is highly unusual in Eumaeini (Valencia-Montoya et al. 2021). The male genitalia (Fig. 3) lack structures that would be useful in determining its closest phylogenetic relatives. More generally, we find no clear-cut morphological evidence to place this species in an available eumaeine genus. The purpose of this paper is to propose new generic and specific names for this newly discovered taxon. One reason is that we need a name to document its unusual leg morphology. Another is that we are currently sequencing its genome for a phylogenetic project. Phylogenetic analysis of the sequence data will allow us to place the genus in the eumaeine Linnaean hierarchy. We predict that it will show, in accord with the findings of Mattoni and Fiedler (1991), that its male foreleg with a clawed pretarsus and five-segmented tarsus evolved from a tarsus that was fused without a pretarsus

    The evolution, distribution and diversity of endogenous circoviral elements in vertebrate genomes

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    Circoviruses (family Circoviridae) are small, non-enveloped viruses that have short, single-stranded DNA genomes. Circovirus sequences are frequently recovered in metagenomic investigations, indicating that these viruses are widespread, yet they remain relatively poorly understood. Endogenous circoviral elements (CVe) are DNA sequences derived from circoviruses that occur in vertebrate genomes. CVe are a useful source of information about the biology and evolution of circoviruses. In this study, we screened 362 vertebrate genome assemblies in silico to generate a catalog of CVe loci. We identified a total of 179 CVe sequences, most of which have not been reported previously. We show that these CVe loci reflect at least 19 distinct germline integration events. We determine the structure of CVe loci, identifying some that show evidence of potential functionalization. We also identify orthologous copies of CVe in snakes, fish, birds, and mammals, allowing us to add new calibrations to the timeline of circovirus evolution. Finally, we observed that some ancient CVe group robustly with contemporary circoviruses in phylogenies, with all sequences within these groups being derived from the same host class or order, implying a hitherto underappreciated stability in circovirus-host relationships. The openly available dataset constructed in this investigation provides new insights into circovirus evolution, and can be used to facilitate further studies of circoviruses and CVe

    Dilaton as the Higgs boson

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    We propose a model where the role of the electroweak Higgs field is played by the dilaton. The model contains terms which explicitly violate gauge invariance, however it is shown that this violation is fictitious, so that the model is a consistent low energy effective theory. In the simplest version of the idea the resulting low energy effective theory is the same as the top mode standard model.Comment: 6 pages, v2 with expanded discussio

    Phylogenetic diversity of insecticolous fusaria inferred from multilocus DNA sequence data and their molecular identification via FUSARIUM-ID and Fusarium MLST

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    We constructed several multilocus DNA sequence datasets to assess the phylogenetic diversity of insecticolous fusaria, especially focusing on those housed at the Agricultural Research Service Collection of Entomopathogenic Fungi (ARSEF), and to aid molecular identifications of unknowns via the FUSARIUM-ID and Fusarium MLST online databases and analysis packages. Analyses of a 190-taxon, two-locus dataset, which included 159 isolates from insects, indicated that: (i) insect-associated fusaria were nested within 10 species complexes spanning the phylogenetic breadth of Fusarium, (ii) novel, putatively unnamed insecticolous species were nested within 8/10 species complexes and (iii) Latin binomials could be applied with confidence to only 18/58 phylogenetically distinct fusaria associated with pest insects. Phylogenetic analyses of an 82-taxon, three-locus dataset nearly fully resolved evolutionary relationships among the 10 clades containing insecticolous fusaria. Multilocus typing of isolates within four species complexes identified surprisingly high genetic diversity in that 63/65 of the fusaria typed represented newly discovered haplotypes. The DNA sequence data, together with corrected ABI sequence chromatograms and alignments, have been uploaded to the following websites dedicated to identifying fusaria: FUSARIUM-ID (http://isolate.fusariumdb.org) a

    Condensation energy in strongly coupled superconductors

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    We consider the condensation energy in superconductors where the pairing is electronic in origin and is mediated by a collective bosonic mode. We use magnetically-mediated superconductivity as an example, and show that for large spin-fermion couplings, the physics is qualitatively different from the BCS theory as the condensation energy results from the feedback on spin excitations, while the electronic contribution to the condensation energy is positive due to an ``undressing'' feedback on the fermions. The same feedback effect accounts for the gain of the kinetic energy at strong couplings.Comment: 4 pages, revtex 4, 3 eps figure

    Hubbard model versus t-J model: The one-particle spectrum

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    The origin of the apparent discrepancies between the one-particle spectra of the Hubbard and t-J models is revealed: Wavefunction corrections, in addition to the three-site terms, should supplement the bare t-J. In this way a quantitative agreement between the two models is obtained, even for the intermediate-UU values appropriate for the high-Tc cuprate superconductors. Numerical results for clusters of up to 20 sites are presented. The momentum dependence of the observed intensities in the photoemission spectra of Sr2CuO2Cl2 are well described by this complete strong-coupling approach.Comment: 4 two-column RevTeX pages, including 4 Postscript figures. Uses epsf. Accepted for publication in Physical Review B, Rapid Communicatio

    Quantum Error Correction via Convex Optimization

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    We show that the problem of designing a quantum information error correcting procedure can be cast as a bi-convex optimization problem, iterating between encoding and recovery, each being a semidefinite program. For a given encoding operator the problem is convex in the recovery operator. For a given method of recovery, the problem is convex in the encoding scheme. This allows us to derive new codes that are locally optimal. We present examples of such codes that can handle errors which are too strong for codes derived by analogy to classical error correction techniques.Comment: 16 page

    Influence of radiative damping on the optical-frequency susceptibility

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    Motivated by recent discussions concerning the manner in which damping appears in the electric polarizability, we show that (a) there is a dependence of the nonresonant contribution on the damping and that (b) the damping enters according to the "opposite sign prescription." We also discuss the related question of how the damping rates in the polarizability are related to energy-level decay rates

    Effect of Magnetic Impurities on Suppression of the Transition Temperature in Disordered Superconductors

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    We calculate the first-order perturbative correction to the transition temperature TcT_c in a superconductor with both non-magnetic and magnetic impurities. We do this by first evaluating the correction to the effective potential, Ω(Δ)\Omega(\Delta), and then obtain the first-order correction to the order parameter, Δ\Delta, by finding the minimum of Ω(Δ)\Omega(\Delta). Setting Δ=0\Delta=0 finally allows TcT_c to be evaluated. TcT_c is now a function of both the resistance per square, R□R_\square, a measure of the non-magnetic disorder, and the spin-flip scattering rate, 1/τs1/\tau_s, a measure of the magnetic disorder. We find that the effective pair-breaking rate per magnetic impurity is virtually independent of the resistance per square of the film, in agreement with an experiment of Chervenak and Valles. This conclusion is supported by both the perturbative calculation, and by a non-perturbative re-summation technique.Comment: 29 pages, 9 figure
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