First Tests of a Precision Beam Phase Masurement System in CTF3

High precision beam phase measurements will be vital for synchronization of main and drive beams in CLIC. Development work is underway with the aim to demonstrate 0.1 degree resolution for a wideband 30 GHz measurement. In order to be able to test this with a beam exhibiting much higher phase jitter, two prototypes have been built so that the difference in their outputs can be measured. Results of measurements made with bunch trains in CTF3 are presented

RF-Based Electron Beam Timing Measurement with Sub-10FS Resolution

Time of flight measurements of a relativistic electron beam have been performed and have demonstrated a resolution below 10 fs. The electronics consisted of a heterodyne receiver incorporating an array of analogue phase detectors in order to reduce noise. The performance of the system makes it suitable for the challenging requirements of intra-pulse train timing measurements in a future linear collider

Precision beam timing measurement system for CLIC synchronization

Very precise synchronization between main and drive beams is required in CLIC to avoid excessive luminosity loss due to energy variations. One possibility to accomplish this would be to measure and correct the drive beam phase. The timing reference for the correction could be the beam in the transfer line between the injector complex and the main linac. The timing of both main and drive beams will have to be measured to a precision in the region of 10 fs. The aim is to achieve this by means of a beam measurement at 30 GHz with the signal mixed down to an intermediate frequency (IF) for precise phase detection. The RF and IF electronics are being developed and tests will be carried out in CTF

Evaluation of far-field tsunami hazard in French Polynesia based on historical data and numerical simulations

International audienceThe first tsunami hazard map of French Polynesia is presented here on the basis of historical data, and numerical simulations. French Polynesia, because of its central position in the most tsunami prone ocean, the Pacific, is strongly exposed to far-field tsunamis. As no previous study on the area had been conducted, we compiled catalogues of all the historical observations (14 events), and tide gauges records (69 marigrams). The catalogues emphasise the higher hazard associated to the Marquesas archipelago, but also the deficiency of robust data in most other parts of French Polynesia. The recourse to numerical simulations allowed us to complement the existing records, and to test tsunami scenarii over different bathymetry and topography configurations, representative of the diversity of islands in French Polynesia. The tsunami hazard map assigns a high exposure level to the Marquesas and the island of Rurutu. Other islands of the Austral, and the Gambier archipelago have a elevated level of exposure, as well as three islands of Society: Tahiti, Moorea, and Huahine. All other islands of French Polynesia are considered as moderately exposed

Diagnostic Infant ABR Testing Via Telehealth: A Survey of Professional Opinions and Current Barriers

Purpose: To examine the barriers to Washington State audiologists adopting telehealth as a means of improving accessibility to diagnostic audiology for infants. Methods: A Qualtrics survey was distributed via e-mail and social media. Survey participants were required to be audiologists practicing in Washington State. The sixteen-question survey consisted of topics related to participant demographics, previous telehealth experience, and barriers to the use of telehealth for diagnostic infant auditory brainstem response (ABR) testing. A total of 17 participants completed the survey. Results: Survey responses indicated that Washington State audiologists are largely neutral or disagree with telehealth being an effective means of performing remote diagnostic ABRs. Participants primarily identified equipment cost as a barrier, and had varying opinions regarding insurance reimbursement, internet connection, privacy, and ability to counsel. Conclusions: This study identified several barriers to the implementation of remote diagnostic ABR testing in Washington State. The neutral and negative view of telehealth for diagnostic infant ABR points to the need for education among Washington State audiologists. Disseminating information on the efficacy of telehealth to audiologists is a likely next step in reframing the current attitude toward remote diagnostic ABR and working toward reducing loss to follow-up rates for rural families

Comparison of measured and predicted bandwidth of graded-index multimode fibres

Measurements of pulse spreading in three graded index fibers have been performed over an extensive range of wavelengths, including regions in which the index profiles become optimal and the bandwidths correspondingly high. The refractive index distributions and profile dispersion parameter have been measured and used in a ray-tracing algorithm in order to predict bandwidths. Comparison reveals that averaging processes on the index data are usually necessary to account for noncircularity of the fiber and small variations in the deduced profile caused by the wavelength dependence of the near-field intensity distribution. Results obtained by this means usually tend to slightly underestimate the true fiber bandwidth, while alpha-profile predictions always result in overestimates by about one order of magnitude. Remaining discrepancies between measured and predicted bandwidths are attributed to small variations of the index profiles along the fiber length

Bayesian inversion for finite fault earthquake source models – II: the 2011 great Tohoku-oki, Japan earthquake

We present a fully Bayesian inversion of kinematic rupture parameters for the 2011 M_w 9 Tohoku-oki, Japan earthquake. Albeit computationally expensive, this approach to kinematic source modelling has the advantage of producing an ensemble of slip models that are consistent with physical a priori constraints, realistic data uncertainties, and realistic but simplistic uncertainties in the physics of the kinematic forward model, all without being biased by non-physical regularization constraints. Combining 1 Hz kinematic GPS, static GPS offsets, seafloor geodesy and near-field and far-field tsunami data into a massively parallel Monte Carlo simulation, we construct an ensemble of samples of the posterior probability density function describing the evolution of fault rupture. We find that most of the slip is concentrated in a depth range of 10–20 km from the trench, and that slip decreases towards the trench with significant displacements at the toe of wedge occurring in just a small region. Estimates of static stress drop and rupture velocity are ambiguous. Due to the spatial compactness of the fault rupture, the duration of the entire rupture was less than approximately 150 s

Personal Wellbeing Score (PWS)—a short version of ONS4: development and validation in social prescribing

Aims Our aim was to develop a short generic measure of subjective well-being for routine use in patient-centred care and healthcare quality improvement alongside other patient-reported outcome and experience measures. Methods The Personal Wellbeing Score (PWS) is based on the Office of National Statistics (ONS) four subjective well-being questions (ONS4) and thresholds. PWS is short, easy to use and has the same look and feel as other measures in the same family of measures. Word length and reading age were compared with eight other measures. Anonymous data sets from five social prescribing projects were analysed. Internal structure was examined using distributions, intra-item correlations, Cronbach’s α and exploratory factor analysis. Construct validity was assessed based on hypothesised associations with health status, health confidence, patient experience, age, gender and number of medications taken. Scores on referral and after referral were used to assess responsiveness. Results Differences between PWS and ONS4 include brevity (42 vs 114 words), reading age (9 vs 12 years), response options (4 vs 11), positive wording throughout and a summary score. 1299 responses (60% female, average age 81 years) from people referred to social prescribing services were analysed; missing values were less than 2%. PWS showed good internal reliability (Cronbach’s α=0.90). Exploratory factor analysis suggested that all PWS items relate to a single dimension. PWS summary scores correlate positively with health confidence (r=0.60), health status (r=0.58), patient experience (r=0.30) and age group (r=0.24). PWS is responsive to social prescribing intervention. Conclusions The PWS is a short variant of ONS4. It is easy to use with good psychometric properties, suitable for routine use in quality improvement and health services research