A fast and lightweight tool for partially coherent beamline simulations in fourth-generation storage rings based on coherent mode decomposition.

A new algorithm to perform coherent mode decomposition of undulator radiation is proposed. It is based on separating the horizontal and vertical directions, reducing the problem by working with one-dimension wavefronts. The validity conditions of this approximation are discussed. Simulations require low computer resources and run interactively on a laptop. The focusing with lenses of the radiation emitted by an undulator in a fourth-generation storage ring (EBS-ESRF) is studied. Results are compared against multiple optics packages implementing a variety of methods for dealing with partial coherence: full two-dimension coherent mode decomposition, Monte Carlo combination of wavefronts from electrons entering the undulator with different initial conditions, and hybrid ray-tracing correcting geometrical optics with wave optics.

Beamline simulations using monochromators with high d-spacing crystals.

Monochromators for synchrotron radiation beamlines typically use perfect crystals for the hard X-ray regime and gratings for soft X-rays. There is an intermediate range, typically 1-3 keV (tender X-rays), which common perfect crystals have difficulties covering and gratings have low efficiency, although some less common crystals with high d-spacing could be suitable. To evaluate the suitability of these crystals for a particular beamline, it is useful to evaluate the crystals' performance using tools such as ray-tracing. However, simulations for double-crystal monochromators are only available for the most used crystals such as Si, Ge or diamond. Here, an upgrade of the SHADOW ray-tracing code and complementary tools in the OASYS suite are presented to simulate high d-spacing crystals with arbitrary, and sometimes complex, structures such as beryl, YB66, muscovite, etc. Isotropic and anisotropic temperature factors are also considered. The YB66 crystal with 1936 atomic sites in the unit cell is simulated, and its applicability for tender X-ray monochromators is discussed in the context of new low-emittance storage rings.

Modelling the effects of optical vibrations on photon beam parameters using ray-tracing software.

A method to simulate beam properties observed at the beamline sample-point in the presence of motion of optical components has been developed at Diamond Light Source. A series of stationary ray-tracing simulations are used to model the impact on the beam stability caused by dynamic motion of optical elements. Ray-tracing simulations using SHADOW3 in OASYS, completed over multiple iterations and stitched together, permit the modelling of a pseudo-dynamic beamline. As beamline detectors operating at higher frequencies become more common, beam stability is crucial. Synchrotron ring upgrades to low-emittance lattices require increased stability of beamlines in order to conserve beam brightness. By simulating the change in beam size and position, an estimate of the impact the motion of various components have on stability is possible. The results presented in this paper focus on modelling the physical vibration of optical elements. Multiple beam parameters can be analysed in succession without manual input. The simulation code is described and the initial results obtained are presented. This method can be applied during beamline design and operation for the identification of optical elements that may introduce large errors in the beam properties at the sample-point.

Compensation of heat load deformations using adaptive optics for the ALS upgrade: a wave optics study.

A realistic wave optics simulation method has been developed to study how wavefront distortions originating from heat load deformations can be corrected using adaptive X-ray optics. Several planned soft X-ray and tender X-ray insertion-device beamlines in the Advanced Light Source upgrade rely on a common design principle. A flat, first mirror intercepts the white beam; vertical focusing is provided by a variable-line-space monochromator; and horizontal focusing comes from a single, pre-figured, adaptive mirror. A variety of scenarios to cope with thermal distortion in the first mirror are studied by finite-element analysis. The degradation of the intensity distribution at the focal plane is analyzed and the adaptive optics that correct it is modeled. The range of correctable wavefront errors across the operating range of the beamlines is reported in terms of mirror curvature and spatial frequencies. The software developed is a one-dimensional wavefront propagation package made available in the OASYS suite, an adaptable, customizable and efficient beamline modeling platform.

Bandage contact lens retention in dogs-A pilot study.

OBJECTIVE: To assess and compare retention, application characteristics, and patient tolerance of nine bandage contact lens types from four manufacturers. ANIMALS STUDIED: Six research Beagles were used in this pilot study. PROCEDURE: Five bandage contact lens types from two veterinary brands and four bandage contact lens types from two human brands were evaluated in six research Beagles. Placement ease, the dogs' contact lens tolerance, and contact lens retention time for up to 14 days were recorded. Statistical analysis with a linear mixed model was performed. RESULTS: Veterinary contact lenses had an average retention time of 0.4 days (range 0-7 days, with an average of 10% and 3% retained ≥1 and ≥7 days, respectively), while human contact lenses had a significantly (P < 0.0001) longer average retention time of 5.2 days (range 0-14 days, with an average of 83% and 37.5% retained ≥1 and ≥7 days, respectively). Specifically, Johnson and Johnson Vision Care Acuvue® Oasys™ with Hydraclear™ Plus lenses were retained significantly longer than all veterinary lenses, and Bausch and Lomb PureVision® 2 lenses were retained significantly longer than Keragenix HydroBlues™ 18 and AnimaLens™ HRT 78 18 mm lenses. CONCLUSION: Although all bandage contact lenses were easy to use and well tolerated by the dogs, the human lenses were retained significantly better and longer than the veterinary lenses. Additionally, human lenses were retained significantly better and longer than veterinary lenses of similar measurements. This suggests factors other than measurement and associated fit may determine contact lens retention time.

Can serial PEF measurements separate occupational asthma from allergic alveolitis?

BACKGROUND: Occupational asthma commonly results in work-related changes in serial peak expiratory flow (PEF) measurements. Whether alveolitis can result in similar changes is unknown. AIMS: To identify differences and similarities of serial PEF between workers with occupational alveolitis and asthma seen during an outbreak investigation in a factory with metal-working fluid exposure. METHODS: Workers with respiratory symptoms and rest-day improvement were identified by questionnaire. Each was asked to measure PEF 8 times daily for 4 weeks at home and work. Alveolitis was subsequently diagnosed from a validated scoring system including radiological changes, carbon monoxide diffusing capacity, bronchoalveolar lavage and biopsy results. Occupational asthma was confirmed with a positive Oasys score >2.5 and a mean rest-work PEF >16 l/min from serial 2-hourly PEF measurements. The Oasys PEF plotter calculated differences between rest and workdays for mean PEF, diurnal variation and the scores were used to confirm an occupational effect (Oasys, area between curve and time point). Records were compared between the alveolitis group and the group with occupational asthma without alveolitis. RESULTS: Forty workers with occupational asthma and 16 with alveolitis had indistinguishable PEF changes on workdays in terms of magnitude (median reduction 18.5 and 16.1 l/min, respectively) and diurnal variation. Immediate reactions were more common with occupational asthma and late reactions more common with alveolitis. CONCLUSIONS: PEF responses to metal-working fluid aerosols do not distinguish occupational asthma from alveolitis except in timing. They can be used to identify the workplace as the cause of asthma and also alveolitis.

Work-related peak flow and asthma symptoms in a damp building.

BACKGROUND: Working in damp conditions is associated with asthma, but few studies have used objective testing to document work-related patterns. AIMS: To describe the relationship of peak flow measurements to work-related asthma (WRA) symptoms and WRA among occupants in a damp office building. METHODS: At the beginning of the study, all workers were offered a questionnaire and methacholine challenge testing. Participants were then instructed to perform serial spirometry using handheld spirometers five times per day over a 3 week period. Peak flow data were analysed using OASYS-2 software. We calculated the area between the curves (ABC score) using hours from waking. We considered a score >5.6 L/min/h to be indicative of a work-related pattern. RESULTS: All 24 employees participated in the questionnaire. Seven participants (29%) reported physician-diagnosed asthma with onset after starting work in the building. Almost two-thirds (63%) of participants reported at least one lower respiratory symptom (LRS) occurring one or more times per week in the last 4 weeks. Twenty-two (92%) consented to participate in serial spirometry. Fourteen participants had adequate quality of serial spirometry, five of whom had ABC scores >5.6, ranging from 5.9-23.0. Of these five, two had airways responsiveness, three had current post-hire onset physician-diagnosed asthma and four reported work-related LRS. CONCLUSIONS: We found evidence of work-related changes in serial peak flows among some occupants of an office building with a history of dampness. Serial peak flows may be a useful measure to determine WRA in office settings.

Optical coherence tomography to evaluate the interaction of different edge designs of four different silicone hydrogel lenses with the ocular surface.

PURPOSE: To evaluate the lens edge interaction with the ocular surface with different edge designs using optical coherence tomography and to examine the effect of lens power on the lens edge interactions. METHODS: Four types of silicone hydrogel lenses with different edge designs (round-, semi-round-, chisel-, and knife-edged) at six different powers (+5.0, +3.0, +1.0, -1.0, -3.0, and -5.0 diopters) were fitted to both eyes of 20 healthy volunteers. Optical coherence tomography images were taken at the corneal center and at the limbus within 15-30 minutes after insertion. The images were evaluated with respect to two parameters: conjunctival indentation exerted by the lens edge; and the tear film gaps between the posterior surface of the lens and the ocular surface. The amount of conjunctival indentation was measured with the distortion angle of the conjunctiva at the lens edge. RESULTS: The degree of conjunctival indentation was highest with the chisel-edged design followed by the semi-round design (P<0.0001). Knife- and round-edged lenses exerted similar levels of conjunctival indentation that was significantly lower compared to chisel-edged lens (P<0.001). For each one of the tested lens edge designs, no significant difference was observed in the conjunctival indentation with respect to lens power. The chisel-edged lens produced the highest amount of conjunctival indentation for each one of the six lens powers (P<0.0001). Post-lens tear film gaps at the limbus were observed at most in the round-edge design (P=0.001). CONCLUSION: The fitting properties of contact lenses may be influenced by their edge design but not by their lens power.

Sloshed and sentenced: A prevalence study of alcohol use disorders among offenders in the North East of England.

The annual cost of alcohol-related harm in the UK is estimated to be between £17.7 and £25.1 billion with healthcare costs alone reaching £2.7 billion and the costs of alcohol-fuelled crime and disorder accounting for £7.3 billion each year. The aim of the study was to examine the prevalence of alcohol use disorders (AUD) in prison and probation settings in the North East of England, and to compare the ability of the Alcohol Use Disorders Identification Test (AUDIT) and Offender Assessment System (OASys) at identifying alcohol-related need in probation clients. A quantitative prevalence study was carried out using anonymous questionnaires with participants from four prisons and three probation offices in the North East who voluntarily completed the AUDIT questionnaire during a 1-month period in 2006. Response outcomes on AUDIT were compared with OASys scores which identify alcohol-related need in probation. At the time of the study OASys scores were not available for offenders in prison. Seven hundred and fifteen questionnaires were completed. Sixty-three per cent of men and 57% of women were identified as having an AUD with over a third of all individuals scoring within the possibly dependant range (20+ on AUDIT). Around 40% of probation cases who were classified as either hazardous, harmful or possibly dependant drinkers on AUDIT were not identified by OASys. The results indicate that the prevalence of AUD in offenders is much higher than in the general population. In addition, current methods of identifying offenders with alcohol-related need in probation are flawed and as many such people go undetected. Alcohol assessment procedures need to be improved in criminal justice setting order to correctly identify people with AUD.