1,420 research outputs found
Regge behaviour and Regge trajectory for ladder graphs in scalar field theory
Using the gaussian representation for propagators (which can be proved to be
exact in the infinite number of loops limit) we are able to derive the Regge
behaviour for ladder graphs of field theory in a completely new way.
An analytic expression for the Regge trajectory is found in
terms of the mean-values of the Feynman -parameters.
is calculated in the range . The intercept
agrees with that obtained from earlier calculations using the Bethe-Salpeter
approach for \alpha (0) \gsim 0.3.Comment: 10 PlainTex pages, 2 PostScript Figures include
Detection of Chlamydiaceae in ocular swabs from Australian pre-export feedlot sheep
Infectious Ovine Keratoconjunctivitis (IOK) is a contagious ocular disease of sheep. A range of organisms have been observed as the aetiological agents of IOK. In this study, the presence of chlamydial pathogens (C. pecorum, C. abortus, C. psittaci) in conjunctival swabs was tested for. The swabs were collected from sheep with varying grades of IOK in an Australian pre-export feedlot. The sheep had been rejected from a shipment because of the eye disease. The relative contribution of chlamydial pathogens to IOK and the rejection of animals was evaluated. In total, 149 conjunctival swabs were taken from rejected sheep (IOK Grades 1 to 6; n = 126) as well as those with healthy eyes (Grade 0; n = 23). Screening for chlamydial pathogens was done using speciesâspecific qPCR assays. Chlamydial DNA was detected in 35.6% (53/149) of conjunctival samples. C. pecorum was the most predominant species with an overall prevalence of 28.9% (43/149). C. psittaci prevalence was 6.7% (10/149). Both organisms were detected in healthy as well as IOK-affected eyes. All swabs tested negative for C. abortus. The results from this study demonstrate that Chlamydia spp can be readily detected in sheep presenting with IOK. The zoonotic C. abortus was not detected in any of the samples in this study, providing further evidence to the suggestion that this pathogen remains absent from Australia. Although the exact contribution of Chlamydia spp in the IOK pathogenesis is unclear, such studies are anticipated to be of benefit to Australian domestic and live export production systems
Proposal for the Measurement of Bell-like Correlations from Continuous Variables
We show theoretically that Bell-type correlations can be observed between
continuous variable measurements performed on a parametric source. An auxiliary
measurement, performed on the detection environment, negates the possibility of
constructing a local realistic description of these correlations
Willingness to participate in a randomized trial comparing catheters to fistulas for vascular access in incident hemodialysis patients: an international survey of nephrologists
BACKGROUND: Current guidelines favor fistulas over catheters as vascular access. Yet, the observational literature comparing fistulas to catheters has important limitations and biases that may be difficult to overcome in the absence of randomization. However, it is not clear if physicians would be willing to participate in a clinical trial comparing fistulas to catheters.
OBJECTIVES: We also sought to elicit participants' opinions on willingness to participate in a future trial regarding catheters and fistulas.
DESIGN: We created a three-part survey consisting of 19 questions. We collected demographic information, respondents' knowledge of the vascular access literature, appropriateness of current guideline recommendations, and their willingness to participate in a future trial.
SETTING: Participants were recruited from Canada, Europe, Australia, and New Zealand.
PARTICIPANTS: Participants include physicians and trainees who are involved in the care of end-stage renal disease patients requiring vascular access.
MEASUREMENTS: Descriptive statistics were used to describe baseline characteristics of respondents according to geographic location. We used logistic regression to model willingness to participate in a future trial.
METHODS: We surveyed nephrologists from Canada, Europe, Australia, and New Zealand to assess their willingness to participate in a randomized trial comparing fistulas to catheters in incident hemodialysis patients.
RESULTS: Our results show that in Canada, 86 % of respondents were willing to participate in a trial (32 % in all patients; 54 % only in patients at high risk of primary failure). In Europe and Australia/New Zealand, the willingness to participate in a trial that included all patients was lower (28 % in Europe; 25 % in Australia/New Zealand), as was a trial that included patients at high risk of primary failure (38 % in Europe; 39 % in Australia/New Zealand). Nephrologists who have been in practice for a few years, saw a larger volume of patients, or self-identified as experts in vascular access literature were more likely to participate in a trial.
LIMITATIONS: Survey distribution was limited to vascular access experts in participating European countries and ultimately led to a discrepancy in numbers of European to non-European respondents overall. Canadian views are likely over-represented in the overall outcomes.
CONCLUSIONS: Our survey results suggest that nephrologists believe there is equipoise surrounding the optimal vascular access strategy and that a randomized controlled study should be undertaken, but restricted to those individuals with a high risk of primary fistula failure
Criminal narrative experience: relating emotions to offence narrative roles during crime commission
A neglected area of research within criminality has been that of the experience of the offence for the offender. The present study investigates the emotions and narrative roles that are experienced by an offender while committing a broad range of crimes and proposes a model of Criminal Narrative Experience (CNE). Hypotheses were derived from the Circumplex of Emotions (Russell, 1997), Frye (1957), Narrative Theory (McAdams, 1988) and its link with Investigative Psychology (Canter, 1994). The analysis was based on 120 cases. Convicted for a variety of crimes, incarcerated criminals were interviewed and the data were subjected to Smallest Space Analysis (SSA). Four themes of Criminal Narrative Experience (CNE) were identified: Elated Hero, Calm Professional, Distressed Revenger and Depressed Victim in line with the recent theoretical framework posited for Narrative Offence Roles (Youngs & Canter, 2012). The theoretical implications for understanding crime on the basis of the Criminal Narrative Experience (CNE) as well as practical implications are discussed
Exploring Andragogy: Understanding the Implications for Teaching in Higher Education
Andragogy is the theory and practice of educating adults. What are the differences between teaching HE students of different age groups? Do these differences become more prevalent with age, and does this matter? Should we revise our teaching practices to maximise engagement with mature students
Comparison of Boltzmann Kinetics with Quantum Dynamics for a Chiral Yukawa Model Far From Equilibrium
Boltzmann equations are often used to describe the non-equilibrium
time-evolution of many-body systems in particle physics. Prominent examples are
the computation of the baryon asymmetry of the universe and the evolution of
the quark-gluon plasma after a relativistic heavy ion collision. However,
Boltzmann equations are only a classical approximation of the quantum
thermalization process, which is described by so-called Kadanoff-Baym
equations. This raises the question how reliable Boltzmann equations are as
approximations to the complete Kadanoff-Baym equations. Therefore, we present
in this article a detailed comparison of Boltzmann and Kadanoff-Baym equations
in the framework of a chirally invariant Yukawa-type quantum field theory
including fermions and scalars. The obtained numerical results reveal
significant differences between both types of equations. Apart from
quantitative differences, on a qualitative level the late-time universality
respected by Kadanoff-Baym equations is severely restricted in the case of
Boltzmann equations. Furthermore, Kadanoff-Baym equations strongly separate the
time scales between kinetic and chemical equilibration. In contrast to this
standard Boltzmann equations cannot describe the process of quantum-chemical
equilibration, and consequently also cannot feature the above separation of
time scales.Comment: 17 pages, 8 figures, REVTeX
The Mach-Zehnder and the Teleporter
We suggest a self-testing teleportation configuration for photon q-bits based
on a Mach-Zehnder interferometer. That is, Bob can tell how well the input
state has been teleported without knowing what that input state was. One could
imagine building a "locked" teleporter based on this configuration. The
analysis is performed for continuous variable teleportation but the arrangement
could equally be applied to discrete manipulations.Comment: 4 pages, 5 figure
Entanglement swapping using continuous variables
We investigate the efficacy with which entanglement can be teleported using a
continuous measurement scheme. We show that by using the correct gain for the
classical channel the degree of violation of locality that can be demonstrated
(using a CH type inequality) is {\it not} a function of the level of
entanglement squeezing used in the teleportation. This is possible because a
gain condition can always be choosen such that passage through the teleporter
is equivalent to pure attenuation of the input field.Comment: 8 pages, 4 figure
Quantum trajectories for the realistic measurement of a solid-state charge qubit
We present a new model for the continuous measurement of a coupled quantum
dot charge qubit. We model the effects of a realistic measurement, namely
adding noise to, and filtering, the current through the detector. This is
achieved by embedding the detector in an equivalent circuit for measurement.
Our aim is to describe the evolution of the qubit state conditioned on the
macroscopic output of the external circuit. We achieve this by generalizing a
recently developed quantum trajectory theory for realistic photodetectors [P.
Warszawski, H. M. Wiseman and H. Mabuchi, Phys. Rev. A_65_ 023802 (2002)] to
treat solid-state detectors. This yields stochastic equations whose (numerical)
solutions are the ``realistic quantum trajectories'' of the conditioned qubit
state. We derive our general theory in the context of a low transparency
quantum point contact. Areas of application for our theory and its relation to
previous work are discussed.Comment: 7 pages, 2 figures. Shorter, significantly modified, updated versio
- âŠ