810 research outputs found
Investigations of the pi N total cross sections at high energies using new FESR: log nu or (log nu)^2
We propose to use rich informations on pi p total cross sections below N= 10
GeV in addition to high-energy data in order to discriminate whether these
cross sections increase like log nu or (log nu)^2 at high energies, since it is
difficult to discriminate between asymptotic log nu and (log nu)^2 fits from
high-energy data alone. A finite-energy sum rule (FESR) which is derived in the
spirit of the P' sum rule as well as the n=1 moment FESR have been required to
constrain the high-energy parameters. We then searched for the best fit of pi p
total cross sections above 70 GeV in terms of high-energy parameters
constrained by these two FESR. We can show from this analysis that the (log
nu)^2 behaviours is preferred to the log nu behaviours.Comment: to be published in Phys. Rev. D 5 pages, 2 eps figure
Thermal modelling of a small wind turbine gearbox for condition monitoring
This paper details the development of a mathematical thermal model of a small wind turbine gearbox for use in condition monitoring. The model was optimised and partially validated using experimental data from a wind turbine drivetrain test rig. The model was then used to mimic bearing faults, by simulating additional heat losses at respective faulty components. The extent to which the thermal behaviour changed as a result of a fault was studied, with a view to use such an approach to detect and locate faults
The future of higher education (HE) hangs on innovating our assessment – but are we ready, willing and able?
Graduates are entering a sociotechnological world, with teaching and assessment needing to reflect that, by shifting from a ‘recall-on-paper’ to ‘do-it-for-real’. With increasing student numbers, it is not feasible to have staff-student ratios and round-the-clock availability required to provide instant feedback and ever-more interactive teaching sessions, so digital solutions are the only option. There is already growing comfort with using computers in formal assessment; however, more work is required to extend beyond performance indicators enabling digital assessments, to addressing how students apply their learning to relevant work-based scenarios. This opinion piece discusses the issues HE currently face to ensure students develop the employability skills that equip them to be proficient in the skills directly related to their degree subject but also transferable to other graduate careers. It raises possible solutions to current technological problems in developing more computer-based assessment, to enable academics to design assessments that develop the capabilities students need
Generalized transparency in semi-inclusive processes
It is argued that the transparency of a medium for passage of a nucleon,
knocked-out in a semi-inclusive reaction and subsequently scattered
elastically, is not the same as the one measured in purely elastic scattering.
Expressions are given for the properly generalized transparency and those are
compared with recently proposed, alternative suggestions. Numerical results are
presented for selected nuclear targets and kinematic conditions, applying to
the Garino et al and the SLAC NE18 experiment.Comment: 24p.; added topdraw file for figures; WIS-93/48/Jun-P
Finite sum of gluon ladders and high energy cross sections
A model for the Pomeron at is suggested. It is based on the idea of a
finite sum of ladder diagrams in QCD. Accordingly, the number of -channel
gluon rungs and correspondingly the powers of logarithms in the forward
scattering amplitude depends on the phase space (energy) available, i.e. as
energy increases, progressively new prongs with additional gluon rungs in the
-channel open. Explicit expressions for the total cross section involving
two and three rungs or, alternatively, three and four prongs (with
and as highest terms, respectively) are fitted to the proton-proton
and proton-antiproton total cross section data in the accelerator region. Both
QCD calculation and fits to the data indicate fast convergence of the series.
In the fit, two terms (a constant and a logarithmically rising one) almost
saturate the whole series, the term being small and the next one,
, negligible. Theoretical predictions for the photon-photon total
cross section are also given.Comment: 18 pages, LaTeX, 2 EPS figures, uses axodraw.st
Effects of low-dose oral micronised progesterone on sleep, psychological distress, and breast development in transgender individuals undergoing feminising hormone therapy: a prospective controlled study
Objective: The role of micronised progesterone in hormone regimens for transgender individuals undergoing feminising hormone therapy remains uncertain. We aimed to determine the effect of oral micronised progesterone on sleep quality, psychological distress, and breast development in transgender individuals undergoing feminising hormone therapy. Design: Prospective case–control study. Twenty-three transgender individuals on stable oestradiol treatment newly commencing 100 mg oral progesterone (n = 23) and controls continuing standard care (n = 19) were assessed over 3 months. Methods: Pittsburgh Sleep Quality Index (PSQI), Kessler psychological distress scale (K10), and Tanner stage to assess breast development were assessed at 0 and 3 months. Nonparametric analysis of covariance was used to compare difference s between groups. Results: Compared with controls over 3 months, there was no difference i n PSQI (P = 0.35), K10 (P = 0.64), or Tanner stage (P = 0.42). There was no significant difference in the proportion of individuals with clinically significant improvement in PSQI (25% vs 22%, P = 0.84). One individual had a significant deterioration in psychological distress that improved following the cessation of progesterone. Conclusions: Low-dose progesterone was not associated with changes in sleep quality, psychological distress, or breast development over 3 months follow-up, though there was significant inter-individual variability. Larger, placebo-controlled trials are required to further evaluate different doses of progesterone in feminising hormone therapy regimens.Brendan J Nolan, Aviva S Frydman, Shalem Y Leemaqz, Meg Carroll, Mathis Grossmann, Jeffrey D Zajac and Ada S Cheun
Role of T-type calcium current in identified D-hair mechanoreceptor neurons studied in vitro
Different subsets of dorsal root ganglion (DRG) mechanoreceptors transduce low- and high-intensity mechanical stimuli. It was shown recently that, in vivo, neurotrophin-4 (NT-4)-dependent D-hair mechanoreceptors specifically express a voltage-activated T-type calcium channel (Ca(v)3.2) that may be required for their mechanoreceptive function. Here we show that D-hair mechanoreceptors can be identified in vitro by a rosette-like morphology in the presence of NT-4 and that these rosette neurons are almost all absent in DRG cultures taken from NT-4 knock-out mice. In vitro identification of the D-hair mechanoreceptor allowed us to explore the electrophysiological properties of these cells. We demonstrate that the T-type Ca(v)3.2 channel induced slow membrane depolarization that contributes to lower the voltage threshold for action potential generation and controls spike latency after stimulation of D-hair mechanoreceptors. Indeed, the properties of the T-type amplifier are particularly well suited to explain the high sensitivity of D-hair mechanoreceptors to slowly moving stimuli
Controlling spatiotemporal chaos in oscillatory reaction-diffusion systems by time-delay autosynchronization
Diffusion-induced turbulence in spatially extended oscillatory media near a
supercritical Hopf bifurcation can be controlled by applying global time-delay
autosynchronization. We consider the complex Ginzburg-Landau equation in the
Benjamin-Feir unstable regime and analytically investigate the stability of
uniform oscillations depending on the feedback parameters. We show that a
noninvasive stabilization of uniform oscillations is not possible in this type
of systems. The synchronization diagram in the plane spanned by the feedback
parameters is derived. Numerical simulations confirm the analytical results and
give additional information on the spatiotemporal dynamics of the system close
to complete synchronization.Comment: 19 pages, 10 figures submitted to Physica
Illusory Decoherence
If a quantum experiment includes random processes, then the results of
repeated measurements can appear consistent with irreversible decoherence even
if the system's evolution prior to measurement was reversible and unitary. Two
thought experiments are constructed as examples.Comment: 10 pages, 3 figure
Coherent States and Modified de Broglie-Bohm Complex Quantum Trajectories
This paper examines the nature of classical correspondence in the case of
coherent states at the level of quantum trajectories. We first show that for a
harmonic oscillator, the coherent state complex quantum trajectories and the
complex classical trajectories are identical to each other. This congruence in
the complex plane, not restricted to high quantum numbers alone, illustrates
that the harmonic oscillator in a coherent state executes classical motion. The
quantum trajectories are those conceived in a modified de Broglie-Bohm scheme
and we note that identical classical and quantum trajectories for coherent
states are obtained only in the present approach. The study is extended to
Gazeau-Klauder and SUSY quantum mechanics-based coherent states of a particle
in an infinite potential well and that in a symmetric Poschl-Teller (PT)
potential by solving for the trajectories numerically. For the coherent state
of the infinite potential well, almost identical classical and quantum
trajectories are obtained whereas for the PT potential, though classical
trajectories are not regained, a periodic motion results as t --> \infty.Comment: More example
- …