561 research outputs found

    A Redescription of Periclimenes yaldwyni Holthuis (Brachycarpus audouini Bate, 1888, Crustacea, Decapoda, Palaemonidae) and Its Occurrence in Australian Waters

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    The pontoniine shrimp Periclimenes yaldwyni Holthuis is recorded for the first time from Australian waters and is redescribed and figured in detail to augment the original description and illustration provided by Bate (1888) as Brachycarpus audouini. The presently available data on carideans (eight spp.) occurring in both Australian and New Zealand waters are summarized

    Recommendations for Preventing Possible Transmission of Al OS from Tears

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    Recommendations for Preventing Possible Trans­mission of Human T-Lymphotropic Virus Type Ill/ Lymphadenopathy-Associated Virus from Tears

    Bound-free pair production in ultra-relativistic ion collisions at the LHC collider: Analytic approach to the total and differential cross sections

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    A theoretical investigation of the bound-free electron-positron pair production in relativistic heavy ion collisions is presented. Special attention is paid to the positrons emitted under large angles with respect to the beam direction. The measurement of these positrons in coincidence with the down--charged ions is in principle feasible by LHC experiments. In order to provide reliable estimates for such measurements, we employ the equivalent photon approximation together with the Sauter approach and derive simple analytic expressions for the differential pair--production cross section, which compare favorably to the results of available numerical calculations. Based on the analytic expressions, detailed calculations are performed for collisions of bare Pb82+^{82+} ions, taking typical experimental conditions of the LHC experiments into account. We find that the expected count rate strongly depends on the experimental parameters and may be significantly enhanced by increasing the positron-detector acceptance cone.Comment: 10 pages, 4 figure

    Graded Bundles in the Category of Lie Groupoids

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    We define and make initial study of Lie groupoids equipped with a compatible homogeneity (or graded bundle) structure, such objects we will refer to as weighted Lie groupoids. One can think of weighted Lie groupoids as graded manifolds in the category of Lie groupoids. This is a very rich geometrical theory with numerous natural examples. Note that VB-groupoids, extensively studied in the recent literature, form just the particular case of weighted Lie groupoids of degree one. We examine the Lie theory related to weighted groupoids and weighted Lie algebroids, objects defined in a previous publication of the authors, which are graded manifolds in the category of Lie algebroids, showing that they are naturally related via differentiation and integration. In this work we also make an initial study of weighted Poisson-Lie groupoids and weighted Lie bi-algebroids, as well as weighted Courant algebroids

    An optimization principle for deriving nonequilibrium statistical models of Hamiltonian dynamics

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    A general method for deriving closed reduced models of Hamiltonian dynamical systems is developed using techniques from optimization and statistical estimation. As in standard projection operator methods, a set of resolved variables is selected to capture the slow, macroscopic behavior of the system, and the family of quasi-equilibrium probability densities on phase space corresponding to these resolved variables is employed as a statistical model. The macroscopic dynamics of the mean resolved variables is determined by optimizing over paths of these probability densities. Specifically, a cost function is introduced that quantifies the lack-of-fit of such paths to the underlying microscopic dynamics; it is an ensemble-averaged, squared-norm of the residual that results from submitting a path of trial densities to the Liouville equation. The evolution of the macrostate is estimated by minimizing the time integral of the cost function. The value function for this optimization satisfies the associated Hamilton-Jacobi equation, and it determines the optimal relation between the statistical parameters and the irreversible fluxes of the resolved variables, thereby closing the reduced dynamics. The resulting equations for the macroscopic variables have the generic form of governing equations for nonequilibrium thermodynamics, and they furnish a rational extension of the classical equations of linear irreversible thermodynamics beyond the near-equilibrium regime. In particular, the value function is a thermodynamic potential that extends the classical dissipation function and supplies the nonlinear relation between thermodynamics forces and fluxes

    Coherent photon-photon interactions in very peripheral relativistic heavy ion collisions

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    Heavy ions at high velocities provide very strong electromagnetic fields for a very short time. The main characteristics of ultraperipheral relativistic heavy ion collisions are reviewed, characteristic parameters are identified. The main interest in ultraperipheral heavy ion collisions at relativistic ion colliders like the LHC is the interactions of very high energy (equivalent) photons with the countermoving (equivalent) photons and hadrons (protons/ions). The physics of these interactions is quite different from and complementary to the physics of the strong fields achieved with current and future lasers.Comment: 5 pages, 5 figures, invited talk presented at the ELI Workshop and School on Fundamental Physics with Ultra-high Fields (September 29- October 2, 2008, Frauenwoerth, German

    Comparison of three RNA amplification methods as sources of DNA for sequencing

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    DNA products generated from a region of the measles virus genome by three RNA reverse transcription and amplification methods were cloned and sequenced, and the results were compared in order to evaluate the methods' relative fidelities. The methods were: (i) reverse transcription followed by a nested polymerase chain reaction (RT-nPCR), (ii) a combined RT-PCR using rTth polymerase and (iii) nucleic acid sequence-based amplification (NASBA). NASBA was followed by RT-PCR with rTth polymerase or RT using AMV reverse transcriptase to generate DNA products for cloning. Products from all three sets of reactions were cloned into a vector, pT7Blue, and 790 bp of cloned DNA were sequenced and analyzed for base changes to determine the error rates for each amplification method. Sequence analysis of cloned RT-nPCR products showed no errors, whereas cloned rTth mediated RT-PCR products possessed an error rate of 0.38 and cloned NASBA products 0.38. Products generated by NASBA followed by RT-PCR with rTth polymerase possessed an error rate of 1.9. The results indicated that cloned DNA products generated by RT-nPCRs possessed least errors and that for NASBA, RT of reaction products before cloning and sequencing was preferable to using RT-PCR

    Comparison of three RNA amplification methods as sources of DNA for sequencing

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    DNA products generated from a region of the measles virus genome by three RNA reverse transcription and amplification methods were cloned and sequenced, and the results were compared in order to evaluate the methods' relative fidelities. The methods were: (i) reverse transcription followed by a nested polymerase chain reaction (RT-nPCR), (ii) a combined RT-PCR using rTth polymerase and (iii) nucleic acid sequence-based amplification (NASBA). NASBA was followed by RT-PCR with rTth polymerase or RT using AMV reverse transcriptase to generate DNA products for cloning. Products from all three sets of reactions were cloned into a vector, pT7Blue, and 790 bp of cloned DNA were sequenced and analyzed for base changes to determine the error rates for each amplification method. Sequence analysis of cloned RT-nPCR products showed no errors, whereas cloned rTth mediated RT-PCR products possessed an error rate of 0.38 and cloned NASBA products 0.38. Products generated by NASBA followed by RT-PCR with rTth polymerase possessed an error rate of 1.9. The results indicated that cloned DNA products generated by RT-nPCRs possessed least errors and that for NASBA, RT of reaction products before cloning and sequencing was preferable to using RT-PCR

    Toxoplasma gondii is not an important contributor to poor reproductive performance of primiparous ewes from southern Australia: A prospective cohort study

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    Background Toxoplasma gondii causes reproductive losses in sheep worldwide, including Australia. The reproductive performance of primiparous ewes is typically lower than for mature, multiparous ewes, and younger ewes are more likely to be immunologically naïve and therefore more susceptible to reproductive disease if T. gondii infection occurs during pregnancy. The aim of this study was to assess the impact of infection with T. gondii on the reproductive performance of primiparous ewes in southern Australia using a prospective cohort study. This will inform the need for targeted control strategies for T. gondii in Australian sheep. Results Toxoplasma gondii seropositivity using indirect ELISA was detected at 16/28 farms located across southern Australia. Apparent seropositivity to T. gondii was lower in primiparous ewes (1.1, 95% confidence interval (CI) 0.6, 1.8) compared to mature, multiparous ewes (8.1, 95% CI 6.0, 10.5; P < 0.001). Toxoplasma gondii seroconversion during the gestation and lambing period was confirmed for 11/1097 (1.0, 95% CI 0.5, 1.7) of pregnant primiparous ewes that failed to raise a lamb, and 1/161 (0.6, 95% CI 0.1, 2.9) primiparous ewes with confirmed mid-pregnancy abortion. Conclusions Low frequency of detection of T. gondii seroconversion during gestation and low frequency of seropositivity to T. gondii suggests that toxoplasmosis was not an important contributor to reproductive losses in primiparous ewes on farms located over a wide geographical area in southern Australia

    Theory of finite temperature crossovers near quantum critical points close to, or above, their upper-critical dimension

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    A systematic method for the computation of finite temperature (TT) crossover functions near quantum critical points close to, or above, their upper-critical dimension is devised. We describe the physics of the various regions in the TT and critical tuning parameter (tt) plane. The quantum critical point is at T=0T=0, t=0t=0, and in many cases there is a line of finite temperature transitions at T=Tc(t)T = T_c (t), t<0t < 0 with Tc(0)=0T_c (0) = 0. For the relativistic, nn-component ϕ4\phi^4 continuum quantum field theory (which describes lattice quantum rotor (n2n \geq 2) and transverse field Ising (n=1n=1) models) the upper critical dimension is d=3d=3, and for d<3d<3, ϵ=3d\epsilon=3-d is the control parameter over the entire phase diagram. In the region TTc(t)Tc(t)|T - T_c (t)| \ll T_c (t), we obtain an ϵ\epsilon expansion for coupling constants which then are input as arguments of known {\em classical, tricritical,} crossover functions. In the high TT region of the continuum theory, an expansion in integer powers of ϵ\sqrt{\epsilon}, modulo powers of lnϵ\ln \epsilon, holds for all thermodynamic observables, static correlators, and dynamic properties at all Matsubara frequencies; for the imaginary part of correlators at real frequencies (ω\omega), the perturbative ϵ\sqrt{\epsilon} expansion describes quantum relaxation at ωkBT\hbar \omega \sim k_B T or larger, but fails for ωϵkBT\hbar \omega \sim \sqrt{\epsilon} k_B T or smaller. An important principle, underlying the whole calculation, is the analyticity of all observables as functions of tt at t=0t=0, for T>0T>0; indeed, analytic continuation in tt is used to obtain results in a portion of the phase diagram. Our method also applies to a large class of other quantum critical points and their associated continuum quantum field theories.Comment: 36 pages, 4 eps figure
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