275 research outputs found
Successful reduction in contaimination and an increase in blood culture collection rates, following introduction of adult blook culture packs
Assessing the see-and-treat approach for the management of high-grade squamous intraepithelial cervical lesions
Objectives: To assess local histological outcomes in patients with HSIL cytology results on cervical smears, in both the see-and-treat and three-step approach. Study Design: A retrospective analysis of patients with HSIL on cervical cytology was performed, obtaining an 83 patient cohort. The histological result following the primary investigation (colposcopic-directed biopsy or excisional procedure) was noted for each patient together with their demographic variables and HPV status. Results: Of 83 patients with HSIL cytology on cervical smear, 43 underwent LLETZ as a primary procedure, while 40 patients underwent a colposcopic-directed biopsy. There was no statistically significant difference in terms of dermographics and HPV status between the two groups. In those patients who had LLETZ as a primary procedure, 29 had CIN2+ on histology. On the other hand, following colposcopic-directed biopsies, 17 resulted in CIN2+ on histology. Conclusion: The conventional approach within our local setting potentially has inferior sensitivity in picking up CIN2+ lesions when compared to the see-and-treat approach. On the other hand, primary excisional procedures were associated with an overtreatment rate of at least 20.9%, subjecting patients to unnecessary risks. Local improvement of colposcopic skill will aid to reduce this overtreatment rate and missed lesions at biopsy.peer-reviewe
A single trapped atom in front of an oscillating mirror
We investigate the Wigner-Weisskopf decay of a two level atom in front of an
oscillating mirror. This work builds on and extends previous theoretical and
experimental studies of the effects of a static mirror on spontaneous decay and
resonance fluorescence. The spontaneously emitted field is inherently
non-stationary due to the time-dependent boundary conditions and in order to
study its spectral distribution we employ the operational definition of the
spectrum of non-stationary light due to the seminal work by Eberly and
Wodkiewicz. We find a rich dependence of this spectrum as well as of the
effective decay rates and level shifts on the mirror-atom distance and on the
amplitude and frequency of oscillations of the mirror. The results presented
here provide the basis for future studies of more complex setups, where the
motion of the atom and/or the mirror are included as quantum degrees of
freedom.Comment: 10 pages, 12 figures, contribution to the special issue in Optics
Communications devoted to Krzysztof Wodkiewicz's memor
Flow generated by radial flow impellers: PIV measurements and CFD simulations
Particle image velocimetry (PIV) and computational fluid dynamics (CFD) have been used to
investigate the single phase and gas-liquid flow generated by a Scaba SRGT turbine. The key
details of the trailing vortices, the turbulent flow around the impeller blades and the
accumulation of gas have been studied by using PIV measurements and CFD simulations.
Both the experimental and numerical results show that the flow and the trailing vortices are
not altered significantly upon gassing. The simulated results are generally in good agreement
with the experimental findings. The CFD simulations also show that only small low-pressure
regions exist behind the blades of the Scaba turbine compared with the very large lowpressure
zones formed by the Rushton turbine. These results enable better understanding of
the improved performance of the Scaba turbine for gas-liquid dispersions compared with the
Rushton turbine
Multipartite optomechanical entanglement from competing nonlinearities
We investigate the nature of the three-mode interaction inside an
optomechanically-active microtoroid with a sizeable chi^(2) coefficient.
Experimental techniques are quickly advancing to the point where structures
with the necessary properties can be made, and we argue that these provide a
natural setting in which to observe rich dynamics leading, for instance, to
genuine tripartite steady-state entanglement. We also show that this approach
lends itself to a full characterisation of the three-mode state of the system.Comment: 7 pages, 5 figures; comments welcom
Gas-liquid mass transfer : a comparison of down-and up-pumping axial flow impellers with radial impellers
The performance of a down- and up-pumping pitched blade turbine and A315 for gas-liquid dispersion and mass
transfer was evaluated and then compared with that of Rushton and Scaba turbines in a small laboratory scale
vessel. The results show that when the axial flow impellers are operated in the up-pumping mode, the overall
performance is largely improved compared with the down-pumping configuration. Compared with the radial
turbines, the up-pumping A315 has a high gas handling capacity, equivalent to the Scaba turbine and is
economically much more efficient in terms of mass transfer than both turbines. On the other hand, the uppumping
pitched blade turbine is not as well adapted to such applications. Finally, the axial flow impellers in the
down-pumping mode have the lowest performance of all the impellers studied, although the A315 is preferred of
the pitched blade turbine
In-field entanglement distribution over a 96 km-long submarine optical fibre
Techniques for the distribution of quantum-secured cryptographic keys have
reached a level of maturity allowing them to be implemented in all kinds of
environments, away from any form of laboratory infrastructure. Here, we detail
the distribution of entanglement between Malta and Sicily over a 96 km-long
submarine telecommunications optical fibre cable. We used this standard
telecommunications fibre as a quantum channel to distribute
polarisation-entangled photons and were able to observe around 257 photon pairs
per second, with a polarisation visibility above 90%. Our experiment
demonstrates the feasibility of using deployed submarine telecommunications
optical fibres as long-distance quantum channels for polarisation-entangled
photons. This opens up a plethora of possibilities for future experiments and
technological applications using existing infrastructure.Comment: 6 pages, 4 figure
Tnehid ta’ ltim
Ä abra ta’ poeĹĽiji u proĹĽa li tinkludi: Minn fuq il-Barrakka ta’ K. Xuereb – Triqat Mitlufa ta’ Ä orġ Pisani – Għall-mewt ta’ G. K. Chesterton ta’ Karmenu Vassallo – Imħabba u mibegħda ta’ Ä użè Chetcuti – Mill-mewt għall-ħajja! ta’ R. M. B. – Tnehid ta’ ltim ta’ Mario Agius.N/
Gas-liquid flow generated by a pitched blade turbine : PIV measurements and CFD simulations
Axial flow impellers, like pitched blade impellers, are being increasingly used for gas-liquid systems in stirred vessels. In this work we have used particle image velocimetry (PIV) and computational fluid dynamics (CFD) models to investigate gas-liquid flow generated by a down-flow pitched blade turbine. PIV measurements were carried out in a fully baffled stirred vessel (of 0.19 m diameter) with a dished bottom. Angle resolved measurements of the flow field with and without gas dispersion were carried out. An attempt was made to capture key details of the trailing vortex, the accumulation of gas and the flow around the impeller blades. A two-fluid model along with the standard k-e turbulence model was used to simulate dispersed gas-liquid flow in stirred vessel. The computational snapshot approach was used to simulate impeller rotation and was implemented in the commercial CFD code, FLUENT4.5 (of Fluent. Inc., USA). The model predictions were verified by comparison with the PIV measurements and other available experimental data. The computational model and results discussed in this work are useful for better understanding and simulating of gas-liquid flow generated by axial impellers in stirred vessels
Sisyphus Cooling of Electrically Trapped Polyatomic Molecules
The rich internal structure and long-range dipole-dipole interactions
establish polar molecules as unique instruments for quantum-controlled
applications and fundamental investigations. Their potential fully unfolds at
ultracold temperatures, where a plethora of effects is predicted in many-body
physics, quantum information science, ultracold chemistry, and physics beyond
the standard model. These objectives have inspired the development of a wide
range of methods to produce cold molecular ensembles. However, cooling
polyatomic molecules to ultracold temperatures has until now seemed
intractable. Here we report on the experimental realization of opto-electrical
cooling, a paradigm-changing cooling and accumulation method for polar
molecules. Its key attribute is the removal of a large fraction of a molecule's
kinetic energy in each step of the cooling cycle via a Sisyphus effect,
allowing cooling with only few dissipative decay processes. We demonstrate its
potential by reducing the temperature of about 10^6 trapped CH_3F molecules by
a factor of 13.5, with the phase-space density increased by a factor of 29 or a
factor of 70 discounting trap losses. In contrast to other cooling mechanisms,
our scheme proceeds in a trap, cools in all three dimensions, and works for a
large variety of polar molecules. With no fundamental temperature limit
anticipated down to the photon-recoil temperature in the nanokelvin range, our
method eliminates the primary hurdle in producing ultracold polyatomic
molecules. The low temperatures, large molecule numbers and long trapping times
up to 27 s will allow an interaction-dominated regime to be attained, enabling
collision studies and investigation of evaporative cooling toward a BEC of
polyatomic molecules
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