On the Wiener-Hopf solution of water-wave interaction with a submerged elastic or poroelastic plate.

A solution to the problem of water-wave scattering by a semi-infinite submerged thin elastic plate, which is either porous or non-porous, is presented using the Wiener-Hopf technique. The derivation of the Wiener-Hopf equation is rather different from that which is used traditionally in water-waves problems, and it leads to the required equations directly. It is also shown how the solution can be computed straightforwardly using Cauchy-type integrals, which avoids the need to find the roots of the highly non-trivial dispersion equations. We illustrate the method with some numerical computations, focusing on the evolution of an incident wave pulse which illustrates the existence of two transmitted waves in the submerged plate system. The effect of the porosity is studied, and it is shown to influence the shorter-wavelength pulse much more strongly than the longer-wavelength pulse

Empathic and Self-Regulatory Processes Governing Doping Behavior

Evidence associating doping behavior with Moral Disengagement (MD) has accumulated over recent years. However, to date, research examining links between MD and doping has not considered key theoretically-grounded influences and outcomes of MD. As such, there is a need for quantitative research in relevant populations that purposefully examines the explanatory pathways through which MD is thought to operate. Towards this end, the current study examined a conceptually-grounded model of doping behavior that incorporated empathy, doping self-regulatory efficacy (SRE), doping MD, anticipated guilt and self-reported doping/doping susceptibility. Participants were specifically recruited to represent four key physical-activity contexts and consisted of team- (n = 195) and individual- (n = 169) sport athletes and hardcore- (n = 125) and corporate- (n = 121) gym exercisers representing both genders (nmale = 371; nfemale = 239); self-reported lifetime prevalence of doping across the sample was 13.6%. Each participant completed questionnaires assessing the aforementioned variables. Structural equation modelling indicated strong support for all study hypotheses. Specifically, we established: (a) empathy and doping SRE negatively predicted reported doping; (b) the predictive effects of empathy and doping SRE on reported doping were mediated by doping MD and anticipated guilt; (c) doping MD positively predicted reported doping; (d) the predictive effects of doping MD on reported doping were partially mediated by anticipated guilt. Substituting self-reported doping for doping susceptibility, multisample analyses then demonstrated these predictive effects were largely invariant between males and females and across the four physical-activity contexts represented. These findings extend current knowledge on a number of levels, and in doing so aid our understanding of key psychosocial processes that may govern doping behavior across key physical-activity contexts

Strabismus as a Presenting Sign in Retinoblastoma

PURPOSE:To report the presenting signs of retinoblastoma in a large cohort of patients who underwent orthoptic assessment at presentation. METHODS:A retrospective medical chart review was conducted on 131 patients with retinoblastoma who presented consecutively to a single institution during a 6-year period. The main outcome measure was the presenting sign(s) of the disease. RESULTS:Of 131 patients with retinoblastoma, 88 presented with unilateral disease and 43 presented with bilateral disease (mean ages: 22.7 and 14.8 months, respectively). Leukocoria was the presenting sign in 56% of patients, leukocoria and strabismus in 18%, strabismus in 13%, inflammation in 8%, and “other” signs in 5%. The fovea was affected by the retinoblastoma tumor or its sequelae in 75% of patients. Patients who presented with strabismus were significantly more likely to have foveal involvement than patients who presented with leukocoria alone (P = .001). Thirty-one percent of patients had strabismus as a component of their presentation; 63% had exotropia, 23% had esotropia, and 14% had variable strabismus. The percentage of patients with strabismus increased to 66% when small angle and variable strabismus were also considered. Patients with inflammation had worse ocular survival (P < .05). CONCLUSIONS:This study assessed the combination of leukocoria and strabismus as presenting features of retinoblastoma. Foveal involvement is common in patients who have strabismus and may influence decision-making regarding globe salvage. The authors confirmed that exotropia is more common than esotropia in retinoblastoma in the largest cohort to have undergone an orthoptic assessment

Microturbulence in O supergiants

We investigate the role of classical microturbulence in the non-LTE He i/He ii line formation problem for luminous O-type stars. We find that the shapes and strengths of certain saturated He i lines, in particular the triplets λλ4471, 4713 and the singlet λ4921, are sensitive to microturbulent velocities in excess of 5 km s−1. Weaker lines, including most of the He i singlets, are effectively independent of this parameter, as are the Fowler series He ii lines λλ4199, 4541, 5411. We show that this behaviour is due to interaction between direct line-broadening effects in the radiative transfer, and indirect changes in the atmospheric structure and the populations of absorbing states. Using an analysis of high-resolution, high signal-to-noise ratio observations of the O9.7 supergiant HD 152003 as an illustrative example, we show how the introduction of microturbulence in non-LTE models allows consistent fits to be obtained for all blue-region He i lines — including the strong triplets λλ4026, 4713, 4471 — at an assumed solar helium abundance, thereby offering a resolution to the problem of the ‘generalized dilution effect’ described by Voels et al. We argue that by extension this result may also have implications for the so-called ‘helium discrepancy’ identified in OB-type stars by Herrero et al

The Incidence of Binocular Visual Impairment and Blindness in Children with Bilateral Retinoblastoma

Purpose: The study aimed to assess the incidence of and risk factors leading to visual impairment and legal blindness in children with retinoblastoma. Procedures: This is a singlecenter, retrospective case series of all patients with bilateral retinoblastoma presenting from 2010 to 2014. Results: A total of 44 patients were included in the study. Visual impairment was present in 14 (38%) children, legal blindness was present in 7 (19%) children. Bilateral macular tumors (BMT) were associated with visual impairment (12 of 18 patients with BMT, 2 of 19 patients without BMT, p = 0.0006) and legal blindness (7 of 18 patients with BMT, 0 of 19 patients without BMT, p = 0.003).The International Intraocular Retinoblastoma Classification (IIRC) of the better eye also predicted visual impairment (16% in IIRC Group A–C, 75% in IIRC Group D, E, p = 0.004) and blindness (3% eye in IIRC Group A–C, 50% in Group D, E, p = 0.005). Various non-Snellen visual acuity measures were able to predict visual impairment in pre-verbal children, providing them with early assistance. Conclusions: The rates of visual impairment and blindness reported in this paper can be used to counsel families regarding the risk of binocular visual impairment. Early detection and support for visually impaired infants are essential as d

"We also deserve help during the pandemic": The effect of the COVID-19 pandemic on foreign domestic workers in Hong Kong.

The coronavirus disease 2019 (COVID-19) pandemic poses particular challenges for migrant workers around the world. This study explores the unique experiences of foreign domestic workers (FDWs) in Hong Kong, and how COVID-19 impacted their health and economic wellbeing. Interviews with FDWs (n = 15) and key informants (n = 3) were conducted between May and August 2020. FDWs reported a dual-country experience of the pandemic, where they expressed concerns about local transmission risks as well as worries about their family members in their home country. Changes to their current work situation included how their employers treated them, as well as their employment status. FDWs also cited blind spots in the Hong Kong policy response that also affected their experience of the pandemic, including a lack of support from the Hong Kong government. Additional support is needed to mitigate the particularly negative effects of the pandemic on FDWs

The first millikelvin cryocooler (mKCC): Design and performance

The design and performance of the first millikelvin cryocooler (mKCC) is presented. The mKCC is based upon a tandem Adiabatic Demagnetisation Refrigerator (ADR) that uses two single ADRs operated out of phase and connected to a common cold stage to provide continuous cooling. Development of this mKCC is part of an on-going research program to ultimately achieve sub-100 mK continuous cooling and builds upon our previous research, with each single ADR in the mKCC being a fast thermal response miniature ADR using a single crystal tungsten magnetoresistive heat switch as detailed in our 2015 publication [1]. With the mKCC operating from a 3.6 K bath temperature, the goal is to achieve continuous cooling at 250 mK (sub-100 mK is not possible without additional pre-cooling). The mKCC has dimensions of 120 × 56 × 228 mm and a mass of 4.67 kg. It can operate on very fast timescales – each superconducting magnet can be ramped to 2 Tesla in 30 s and the Chromium Potassium Alum pills have a measured sub-second thermal response, resulting in each miniature ADR being recycled in minutes. Unconventionally, the mKCC uses single crystal tungsten magnetoresistive heat switches. We present the performance of the first version of the fully automated mKCC (from a 3.6 K bath temperature), which has been determined by undertaking a range of tests analysing the cool down from 3.6 K to the operating temperature, the baseline performance, the thermal stability at the continuous stage, the reliability and repeatability in performance and the cooling power at a range of operating temperatures. The base temperature has been measured to be 750 mK and we have demonstrated that the mKCC can be operated at any temperature between 750 mK and 3 K, with the program-controlled transition between operating temperatures taking approximately 60 s. The cooling power of the mKCC (in addition to parasitic load) has been measured at a range of temperatures between 800 mK and 3 K by applying a heat load to the continuous stage via a heater; the maximum cooling power at 800 mK is 6 µW, increasing to 32 µW at 1 K and 412 µW at 3 K. In addition we conducted a six-week continuous test during which each ADR undertook 5,498 5.5 min cycles with no significant variation in performance detected. To conclude, we compare the measured performance of the mKCC to the expected performance based on mathematical thermal modelling and the performance of the miniature ADR. Whilst the measured performance does not meet the expected performance in terms of base temperature or cooling power, we have identified the limiting factors and discuss them here