Non-equilibrium Lorentz gas on a curved space

The periodic Lorentz gas with external field and iso-kinetic thermostat is equivalent, by conformal transformation, to a billiard with expanding phase-space and slightly distorted scatterers, for which the trajectories are straight lines. A further time rescaling allows to keep the speed constant in that new geometry. In the hyperbolic regime, the stationary state of this billiard is characterized by a phase-space contraction rate, equal to that of the iso-kinetic Lorentz gas. In contrast to the iso-kinetic Lorentz gas where phase-space contraction occurs in the bulk, the phase-space contraction rate here takes place at the periodic boundaries

Predictors of Spectacle Wear and Reasons for Nonwear in Students Randomized to Ready-made or Custom-made Spectacles: Results of Secondary Objectives From a Randomized Noninferiority Trial.

Importance: Visual impairment from uncorrected refractive errors affects 12.8 million children globally. Spectacle correction is simple and cost-effective; however, low adherence to spectacle wear, which can occur in all income settings, limits visual potential. Objective: To investigate predictors of spectacle wear and reasons for nonwear in students randomized to ready-made or custom-made spectacles. Design, Setting, and Participants: In planned secondary objectives of a noninferiority randomized clinical trial, students aged 11 to 15 years who fulfilled eligibility criteria, which included improvement in vision with correction by at least 2 lines in the better eye, were recruited from government schools in Bangalore, India. Recruitment took place between January 12 and July 15, 2015, and analysis for the primary outcome occurred in August 2016. Data analysis for the secondary outcome was conducted in August 2018. Spectacle wear was assessed by masked observers at unannounced visits to schools 3 to 4 months after spectacles were distributed. Students not wearing their spectacles were asked an open-ended question to elicit reasons for nonwear. Main Outcomes and Measures: Predictors of spectacle wear and reasons for nonwear. Results: Of 460 students recruited and randomized (52.2% male; 46 students aged 11 to 12 years and 13 to 15 years in each trial arm), 78.7% (362 of 460) were traced at follow-up, and 25.4% (92 of 362) were not wearing their spectacles (no difference between trial arms). Poorer presenting visual acuity (VA) and improvement in VA with correction predicted spectacle wear. Students initially seen with an uncorrected VA less than 6/18 in the better eye were almost 3 times more likely to be wearing their spectacles than those with less than 6/9 to 6/12 (adjusted odds ratio, 2.84; 95% CI, 1.52-5.27). Improvement of VA with correction of 3 to 6 lines or more than 6 lines had adjusted odds ratios of 2.31 (95% CI, 1.19-4.50) and 2.57 (95% CI, 1.32-5.01), respectively, compared with an improvement of less than 3 lines. The main reason students gave for nonwear was teasing or bullying by peers (48.9% [45 of 92]). Girls reported parental disapproval as a reason more frequently than boys (difference, 7.2%). Conclusions and Relevance: Three-quarters of students receiving spectacles were wearing them at follow-up, which supports the use of the prescribing guidelines applied in this trial. Predictors of spectacle wear, poorer presenting VA, and greater improvement in VA with correction are similar to other studies. Interventions to reduce teasing and bullying are required, and health education of parents is particularly needed for girls in this setting. Trial Registration: isrctn.org Identifier: ISRCTN14715120

A Systematic Literature Review of the Contribution of Past Climate Information Services Pilot Projects in Climate Risk Management

Many pilot-based initiatives have been developed to promote awareness and use of climate information services among vulnerable smallholder farmers in Africa through million-dollar investments. However, despite their experimental nature, these pilot projects have been successful in raising participating farmers’ awareness and use of climate information services and they can inform transferrable good practices. Through a systematic literature review approach, this review sought to understand ways in which these past pilot projects have contributed to climate risk management in the context of smallholder farming and the factors that led to their success. Results showed that climate information services main contribution to climate risk management has been through facilitating farm level decision making. Factors that led to success of the pilots include: use of downscaled information; building institutional partnerships to add value to climate information; involving farmers through the co-designing and co-developing process; face-to-face way of communication; embedding pre-seasonal workshops in the activities of local institutions for sustainability; using diversity of communication channels to enhance reach among others. These factors can be borrowed as good practices to inform future efforts focused on increasing adoption of climate information services among a wider population beyond pilot project reach

The oxygenation of extraction and future global ecological democracy: the City of London, the alternative investment market and oil in frontiers in Africa

This article explores how the governance of the City of London Corporation perpetuates the oxygenation of extraction, with a focus on oil frontiers and ecological impacts in Africa. It shows how this extractive system limits environmental justice through a spider’s web of tax havens linked to the notoriously under-regulated Alternative Investment Market. The contemporary success of the City of London Corporation is supported by an archaic membership system drawn from financial services. This has also allowed it to support the establishment of the most successful network of secrecy jurisdictions of ‘tax havens’ on the planet, supporting flows for illicit business in commodity frontiers. As extractive operations are given life by the financial flows that circulate through the City and its offshore empire, and take control of land, the potential for local communities to utilise their local ecological knowledge is asphyxiated, limiting the protection of food systems and endangered species. The article explains how this system functions, and why it needs to be reformed to limit Earth’s sixth mass extinction. It does so through case studies of the City of London, the Niger Delta and Turkana Kenya, using ethnography and semi structured interviews. A new system of ecological direct democracy is proposed, limiting global corruption flows into the City’s tax havens, allowing instead for a flourishing globalisation of ecological democracy

The fractality of the relaxation modes in deterministic reaction-diffusion systems

In chaotic reaction-diffusion systems with two degrees of freedom, the modes governing the exponential relaxation to the thermodynamic equilibrium present a fractal structure which can be characterized by a Hausdorff dimension. For long wavelength modes, this dimension is related to the Lyapunov exponent and to a reactive diffusion coefficient. This relationship is tested numerically on a reactive multibaker model and on a two-dimensional periodic reactive Lorentz gas. The agreement with the theory is excellent

Primary open angle glaucoma in northern Nigeria: stage at presentation and acceptance of treatment.

BACKGROUND: To determine the stage of primary open angle glaucoma at presentation at a tertiary eye unit, to assess patient's knowledge of glaucoma and acceptance and subsequent adherence to treatment. METHOD: Information collected prospectively on new glaucoma patients aged 30 or more years included distance from residence and what they knew about glaucoma and its treatment. Treatment offered took account of disease severity and socioeconomic factors. Reasons for not accepting surgery were recorded. At follow up intraocular pressure (IOP) was measured and adherence to medication assessed verbally. Four categories of severity were defined based on visual acuity and visual fields defects in the worse eye. RESULTS: 131 patients were recruited (mean age 52.8 years; 62% male). Most attended because of symptoms (70%). Mean IOP in affected eyes was 31.9+/-SD 12.4 and mean vertical cup:disc ratio was 0.8. 99 eyes (47%) had a visual acuity of light perception or worse. Risk factors for advanced/end-stage disease were age >50 years, living >10 km from the hospital, some awareness of glaucoma, not being literate, being unemployed and presenting with symptoms. In multivariable analysis older age and poor knowledge of glaucoma remained independent risk factors. 75 were offered trabeculectomy: five agreed but only one underwent surgery. Reasons for rejecting surgery were fear (37%), preferred medical treatment (27 %) and cost (15 %). 32/85 (24 %) participants started on topical medication attended follow up. 72% reported excellent compliance but only 56% of glaucomatous eyes had IOPs less than 21 mmHg. CONCLUSIONS: To prevent glaucoma blindness strategies are required which promote earlier detection, with counselling to promote acceptance of and adherence to treatment

Reducing inequity of cataract blindness and vision impairment is a global priority, but where is the evidence?

Throughout the world, people who are socially or economically disadvantaged disproportionately experience blindness and vision impairment caused by cataract. Reducing vision loss from cataract and its unequal distribution must be a priority if the WHO's aim of 'universal eye health' is to be realised. To help achieve this, decision-makers and service planners need evidence on which strategies improve access to cataract services among disadvantaged populations, and under what circumstances. Unfortunately, despite many strategies to improve cataract services being implemented in recent decades, evidence of what works, for who and in what circumstances is not readily available. This paper summarises the extent of the evidence on interventions to reduce inequity of vision loss from cataract and makes suggestions for how the evidence base can be strengthened

Spectacle wearing in children randomised to ready-made or custom spectacles, and potential cost savings to programmes: study protocol for a randomised controlled trial.

BACKGROUND: Uncorrected refractive errors are the commonest cause of visual impairment in children, with myopia being the most frequent type. Myopia usually starts around 9 years of age and progresses throughout adolescence. Hyperopia usually affects younger children, and astigmatism affects all age groups. Many children have a combination of myopia and astigmatism. To correct refractive errors, the type and degree of refractive error are measured and appropriate corrective lenses prescribed and dispensed in the spectacle frame of choice. Custom spectacles (that is, with the correction specifically required for that individual) are required if astigmatism is present, and/or the refractive error differs between eyes. Spectacles without astigmatic correction and where the refractive error is the same in both eyes are straightforward to dispense. These are known as 'ready-made' spectacles. High-quality spectacles of this type can be produced in high volume at an extremely low cost. Although spectacle correction improves visual function, a high proportion of children do not wear their spectacles for a variety of reasons. The aim of this study is to compare spectacle wear at 3-4 months amongst school children aged 11 to 15 years who have significant, simple uncorrected refractive error randomised to ready-made or custom spectacles of equivalent quality, and to evaluate cost savings to programmes. The study will take place in urban and semi-urban government schools in Bangalore, India. The hypothesis is that similar proportions of children randomised to ready-made or custom spectacles will be wearing their spectacles at 3-4 months. METHODS/DESIGN: The trial is a randomised, non-inferiority, double masked clinical trial of children with simple uncorrected refractive errors. After screening, children will be randomised to ready-made or custom spectacles. Children will choose their preferred frame design. After 3-4 months the children will be followed up to assess spectacle wear. DISCUSSION: Ready-made spectacles have benefits for providers as well as parents and children, as a wide range of prescriptions and frame types can be taken to schools and dispensed immediately. In contrast, custom spectacles have to be individually made up in optical laboratories, and taken back to the school and given to the correct child. TRIAL REGISTRATION: ISRCTN14715120 (Controlled-Trials.com) Date registered: 04 February 2015

Steady-state conduction in self-similar billiards

The self-similar Lorentz billiard channel is a spatially extended deterministic dynamical system which consists of an infinite one-dimensional sequence of cells whose sizes increase monotonically according to their indices. This special geometry induces a nonequilibrium stationary state with particles flowing steadily from the small to the large scales. The corresponding invariant measure has fractal properties reflected by the phase-space contraction rate of the dynamics restricted to a single cell with appropriate boundary conditions. In the near-equilibrium limit, we find numerical agreement between this quantity and the entropy production rate as specified by thermodynamics

Effects of Strong Gravitational Lensing on Millimeter-Wave Galaxy Number Counts

We study the effects of strong lensing on the observed number counts of mm sources using a ray tracing simulation and two number count models of unlensed sources. We employ a quantitative treatment of maximum attainable magnification factor depending on the physical size of the sources, also accounting for effects of lens halo ellipticity. We calculate predicted number counts and redshift distributions of mm galaxies including the effects of strong lensing and compare with the recent source count measurements of the South Pole Telescope (SPT). The predictions have large uncertainties, especially the details of the mass distribution in lens galaxies and the finite extent of sources, but the SPT observations are in good agreement with predictions. The sources detected by SPT are predicted to largely consist of strongly lensed galaxies at z>2. The typical magnifications of these sources strongly depends on both the assumed unlensed source counts and the flux of the observed sources