999 research outputs found
Coherent optical phase transfer over a 32-km fiber with 1-s instability at
The phase coherence of an ultrastable optical frequency reference is fully
maintained over actively stabilized fiber networks of lengths exceeding 30 km.
For a 7-km link installed in an urban environment, the transfer instability is
at 1-s. The excess phase noise of 0.15 rad, integrated from
8 mHz to 25 MHz, yields a total timing jitter of 0.085 fs. A 32-km link
achieves similar performance. Using frequency combs at each end of the
coherent-transfer fiber link, a heterodyne beat between two independent
ultrastable lasers, separated by 3.5 km and 163 THz, achieves a 1-Hz linewidth.Comment: 4 pages, 4 figure
New classes of exact solutions of three-dimensional Navier-Stokes equations
New classes of exact solutions of the three-dimensional unsteady
Navier-Stokes equations containing arbitrary functions and parameters are
described. Various periodic and other solutions, which are expressed through
elementary functions are obtained. The general physical interpretation and
classification of solutions is given.Comment: 11 page
From pelvic radiation to social isolation: a qualitative study of survivors’ experiences of chronic bowel symptoms after pelvic radiotherapy
\ua9 2024, The Author(s).Purpose: We explored survivors’ experiences of chronic bowel symptoms following pelvic radiotherapy, strategies employed in living with these symptoms, effects on daily activities, and roles at home and in the workplace. Methods: Semi-structured interviews were conducted with 28 individuals (10 gynaecological, 14 prostate, four anal/rectal cancer survivors) who had completed pelvic radiotherapy at least six months prior to data collection and who had experience of bowel symptoms during this post-treatment period. Reflexive thematic analysis was undertaken. Results: We propose four themes describing a process leading from experience of symptoms to withdrawal from activities and roles. These are (1) losing control (the experience of unintended anal leakage or discharge); (2) experiencing embarrassment and fear (the experience of embarrassment or fear of embarrassment as a result of discharge becoming public); (3) managing and reacting (acting to reduce the likelihood of discharge or to prevent this becoming public); and (4) restriction and withdrawal (avoiding specific activities or situations so as to reduce or remove the risk of embarrassment). Returning to the workplace presented additional challenges across these themes. Conclusions: Impacts of chronic bowel symptoms can be severe. Survivors employ a variety of methods and strategies in living with their symptoms. Some of these support continued role fulfilment but some constitute a withdrawal from pre-treatment roles. Current healthcare provision and statutory protections fail to fully meet needs following pelvic radiotherapy. Implications for cancer survivors. There is a need to develop and implement evidence-based services and supported self-management programmes for survivors experiencing chronic bowel problems post-radiotherapy
Systematic study of the Sr clock transition in an optical lattice
With ultracold Sr confined in a magic wavelength optical lattice, we
present the most precise study (2.8 Hz statistical uncertainty) to-date of the
- optical clock transition with a detailed analysis of
systematic shifts (20 Hz uncertainty) in the absolute frequency measurement of
429 228 004 229 867 Hz. The high resolution permits an investigation of the
optical lattice motional sideband structure. The local oscillator for this
optical atomic clock is a stable diode laser with its Hz-level linewidth
characterized across the optical spectrum using a femtosecond frequency comb.Comment: 4 pages, 4 figures, 1 tabl
Making optical atomic clocks more stable with level laser stabilization
The superb precision of an atomic clock is derived from its stability. Atomic
clocks based on optical (rather than microwave) frequencies are attractive
because of their potential for high stability, which scales with operational
frequency. Nevertheless, optical clocks have not yet realized this vast
potential, due in large part to limitations of the laser used to excite the
atomic resonance. To address this problem, we demonstrate a cavity-stabilized
laser system with a reduced thermal noise floor, exhibiting a fractional
frequency instability of . We use this laser as a stable
optical source in a Yb optical lattice clock to resolve an ultranarrow 1 Hz
transition linewidth. With the stable laser source and the signal to noise
ratio (S/N) afforded by the Yb optical clock, we dramatically reduce key
stability limitations of the clock, and make measurements consistent with a
clock instability of
Understanding the impact of diet and nutrition on symptoms of Tourette Syndrome: A Scoping Review
This document is the accepted manuscript version. The final, definitive version of this paper has been published in Journal of Child Health Care, December 2017, published by SAGE Publishing, doi:https://doi.org/10.1177/1367493517748373.Anecdotal reports frequently suggest some dietary involvement in the maintenance of tics in children with Tourette syndrome (TS). This scoping review aimed to (1) understand the possible influence of diet as a trigger of tics and (2) map out the existing studies documenting dietary interventions in children with TS. Current evidence suggests no single diet to benefit individuals with TS. However, reports from parents of children with TS suggest that certain allergens in food may exacerbate tic-related symptoms. For example, an increase in tics has been related to the consumption of caffeine and refined sugar. Moreover, oligoantigenic diets and sugar-free diets have been identified as significantly reducing tics. More research is urgently needed to develop more accurate guidance for parents and children with TS, as many have reported using dietary and nutritional supplements, despite the lack of evidence detailing any benefits, side effects and recommended doses.Peer reviewedFinal Accepted Versio
Sub-recoil clock-transition laser cooling enabling shallow optical lattice clocks
Laser cooling is a key ingredient for quantum control of atomic systems in a
variety of settings. In divalent atoms, two-stage Doppler cooling is typically
used to bring atoms to the uK regime. Here, we implement a pulsed radial
cooling scheme using the ultranarrow 1S0-3P0 clock transition in ytterbium to
realize sub-recoil temperatures, down to tens of nK. Together with sideband
cooling along the one-dimensional lattice axis, we efficiently prepare atoms in
shallow lattices at an energy of 6 lattice recoils. Under these conditions key
limits on lattice clock accuracy and instability are reduced, opening the door
to dramatic improvements. Furthermore, tunneling shifts in the shallow lattice
do not compromise clock accuracy at the 10-19 level
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Solids Fraction Measurement with a Reflective Fiber Optic Probe
A method has been developed to extract solids fraction information from a reflective fiber optic probe. The commercially available reflective fiber optic probe was designed to measure axial particle velocity (both up and down directions). However, the reflected light intensity measured is related to particle size and particle concentration. A light reflection model is used to relate the reflected light intensity to solids fraction. In this model we assume that the reflected light intensity is a fixed fraction, K1, of the total light intensity lost in penetration of a solid layer. Also, the solids fraction is related to particle concentration, N, in the light path, by N = K2 (1- ε), where (1-ε) is the solids fraction. The parameters K1 and K2 are determined through a calibration and curve fitting procedure. This paper describes this procedure and the steps taken to derive the values of K1 and K2. It is proposed that the reflective fiber optic can be used for real time measurement of solids fraction in a circulating fluid bed
A high stability semiconductor laser system for a Sr-based optical lattice clock
We describe a frequency stabilized diode laser at 698 nm used for high
resolution spectroscopy of the 1S0-3P0 strontium clock transition. For the
laser stabilization we use state-of-the-art symmetrically suspended optical
cavities optimized for very low thermal noise at room temperature. Two-stage
frequency stabilization to high finesse optical cavities results in measured
laser frequency noise about a factor of three above the cavity thermal noise
between 2 Hz and 11 Hz. With this system, we demonstrate high resolution remote
spectroscopy on the 88Sr clock transition by transferring the laser output over
a phase-noise-compensated 200 m-long fiber link between two separated
laboratories. Our dedicated fiber link ensures a transfer of the optical
carrier with frequency stability of 7 \cdot 10^{-18} after 100 s integration
time, which could enable the observation of the strontium clock transition with
an atomic Q of 10^{14}. Furthermore, with an eye towards the development of
transportable optical clocks, we investigate how the complete laser system
(laser+optics+cavity) can be influenced by environmental disturbances in terms
of both short- and long-term frequency stability.Comment: 9 pages, 9 figures, submitted to Appl. Phys.
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