937 research outputs found
Evaluating the Impact of Chartered Teacher in Scotland: The views of Chartered Teachers: Final Report
Evidence of a link between the evolution of clusters and their AGN fraction
âThe definitive version is available at www3.interscience.wiley.com .' Copyright Blackwell Publishing / Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.14513.xPeer reviewe
Physiological factors associated with low bone mineral density in female endurance runners
This paper details research taken to explore potential factors that could be associated with low bone mineral density (BMD) in female endurance runners. Fifty two female endurance runners (1,500 m to marathon), aged 18-44 years, took part. Body fat percentage, lumbar spine BMD, and femoral neck BMD were measured using the Hologic QDR 4,500w bone densitometer. Data on training, menstrual cycle status, osteoporosis, and health related factors were obtained by questionnaire. Dietary variables were assessed from a prospective seven day dietary record of macronutrients and micronutrients. The results suggest a negative association between endurance running distance and lumbar spine and femoral neck BMD, with a positive association between body mass and femoral neck and lumbar spine BMD. However, longitudinal studies are required to assess directly the effect of endurance running and body mass on BMD, and to see if the addition of alternative exercise that would increase lean body mass would have a positive effect on BMD and therefore help to prevent osteoporosis
Exact beta function from the holographic loop equation of large-N QCD_4
We construct and study a previously defined quantum holographic effective
action whose critical equation implies the holographic loop equation of large-N
QCD_4 for planar self-avoiding loops in a certain regularization scheme. We
extract from the effective action the exact beta function in the given scheme.
For the Wilsonean coupling constant the beta function is exacly one loop and
the first coefficient agrees with its value in perturbation theory. For the
canonical coupling constant the exact beta function has a NSVZ form and the
first two coefficients agree with their value in perturbation theory.Comment: 42 pages, latex. The exponent of the Vandermonde determinant in the
quantum effective action has been changed, because it has been employed a
holomorphic rather than a hermitean resolution of identity in the functional
integral. Beta function unchanged. New explanations and references added,
typos correcte
Optimized and accelerated 19FâMRI of inhaled perfluoropropane to assess regional pulmonary ventilation
Purpose
To accelerate 19FâMR imaging of inhaled perfluoropropane using compressed sensing methods, and to optimize critical scan acquisition parameters for assessment of lung ventilation properties.
Methods
Simulations were performed to determine optimal acquisition parameters for maximal perfluoropropane signalâtoânoise ratio (SNR) in human lungs for a spoiled gradient echo sequence. Optimized parameters were subsequently employed for 19FâMRI of inhaled perfluoropropane in a cohort of 11 healthy participants using a 3.0 T scanner. The impact of 1.8Ă, 2.4Ă, and 3.0Ă undersampling ratios on 19FâMRI acquisitions was evaluated, using both retrospective and prospective compressed sensing methods.
Results
3D spoiled gradient echo 19FâMR ventilation images were acquired at 1âcm isotropic resolution within a single breath hold. Mean SNR was 11.7 ± 4.1 for scans acquired within a single breath hold (duration = 18 s). Acquisition of 19FâMRI scans at shorter scan durations (4.5 s) was also demonstrated as feasible. Application of both retrospective (n = 8) and prospective (n = 3) compressed sensing methods demonstrated that 1.8Ă acceleration had negligible impact on qualitative image appearance, with no statistically significant change in measured lung ventilated volume. Acceleration factors of 2.4Ă and 3.0Ă resulted in increasing differences between fully sampled and undersampled datasets.
Conclusion
This study demonstrates methods for determining optimal acquisition parameters for 19FâMRI of inhaled perfluoropropane and shows significant reduction in scan acquisition times (and thus participant breath hold duration) by use of compressed sensing
Quantitative Behavioural Reasoning for Higher-order Effectful Programs: Applicative Distances (Extended Version)
This paper studies the quantitative refinements of Abramsky's applicative
similarity and bisimilarity in the context of a generalisation of Fuzz, a
call-by-value -calculus with a linear type system that can express
programs sensitivity, enriched with algebraic operations \emph{\`a la} Plotkin
and Power. To do so a general, abstract framework for studying behavioural
relations taking values over quantales is defined according to Lawvere's
analysis of generalised metric spaces. Barr's notion of relator (or lax
extension) is then extended to quantale-valued relations adapting and extending
results from the field of monoidal topology. Abstract notions of
quantale-valued effectful applicative similarity and bisimilarity are then
defined and proved to be a compatible generalised metric (in the sense of
Lawvere) and pseudometric, respectively, under mild conditions
Soluble granzymes are released during human endotoxemia and in patients with severe infection due to gram-negative bacteria
Ultrasonic Cutting Device for Bone Surgery Based on a Cymbal Transducer
AbstractIn this study, we introduce a new prototype ultrasonic cutting device for bone surgery based on a class V flextensional cymbal transducer, configured for use in power ultrasonics applications, which removes many of the geometrical restrictions on the cutting tip of Langevin-based transducers. The benefit of incorporating a cymbal transducer is that since the cutting blade itself does not have to be tuned, blade design can focus more closely on delivering the best interaction with bone to provide a highly accurate cut. Small variations to the geometry of the blade do not affect the final resonance frequency. Also the ultrasonic device can be miniaturised to allow the design of devices for delicate orthopaedic procedures involving minimal-access surgery. The results show how the cymbal transducer, driven by a single piezoceramic disc, can excite sufficiently high vibration displacement amplitudes at lower driving voltages. This is achieved by adapting the configuration of the cymbal to remove the problem of epoxy layer debonding, and by optimising the cymbal end-cap and geometry through finite element modelling supported with experimental vibration characterisation. Preliminary characterisations of the resulting prototype ultrasonic bone cutting device, which operates at around 25kHz, illustrate the success of this novel device design
Twisted local systems solve the (holographic) loop equation of large-N QCD_4
We construct a holographic map from the loop equation of large-N QCD in d=2
and d=4, for planar self-avoiding loops, to the critical equation of an
equivalent effective action. The holographic map is based on two ingredients:
an already proposed holographic form of the loop equation, such that the
quantum contribution is reduced to a regularized residue; a new conformal map
from the region encircled by the based loop to a cuspidal fundamental domain in
the upper half-plane, such that the regularized residue vanishes at the cusp.
As a check, we study the first coefficient of the beta function and that part
of the second coefficient which arises from the rescaling anomaly, in passing
from the Wilsonian to the canonically normalised (holographic) effective
action.Comment: 42 pages, latex; abstract shortened and a reference added as
suggested by the referee; typos in Eq.(72,76,77,82,83,84) correcte
Hypolytrum (Cyperaceae): taxonomic and nomenclatural notes, geographical distribution and conservation status of Neotropical species
- âŠ