575 research outputs found
A Redescription of Periclimenes yaldwyni Holthuis (Brachycarpus audouini Bate, 1888, Crustacea, Decapoda, Palaemonidae) and Its Occurrence in Australian Waters
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
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
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 Pb 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
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
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
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
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
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
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
A systematic method for the computation of finite temperature () 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
and critical tuning parameter () plane. The quantum critical point is at
, , and in many cases there is a line of finite temperature
transitions at , with . For the relativistic,
-component continuum quantum field theory (which describes lattice
quantum rotor () and transverse field Ising () models) the upper
critical dimension is , and for , is the control
parameter over the entire phase diagram. In the region , we obtain an expansion for coupling constants which then are
input as arguments of known {\em classical, tricritical,} crossover functions.
In the high region of the continuum theory, an expansion in integer powers
of , modulo powers of , holds for all
thermodynamic observables, static correlators, and dynamic properties at all
Matsubara frequencies; for the imaginary part of correlators at real
frequencies (), the perturbative expansion describes
quantum relaxation at or larger, but fails for or smaller. An important principle,
underlying the whole calculation, is the analyticity of all observables as
functions of at , for ; indeed, analytic continuation in 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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