Factors Associated With Retinal Vessel Diameters in an Elderly Population: the Thessaloniki Eye Study

Purpose: To identify the factors associated with retinal vessel diameters in the population of the Thessaloniki Eye Study. Methods: Cross-sectional population-based study (age ≥ 60 years). Subjects with glaucoma, late age-related macular degeneration, and diabetic retinopathy were excluded from the analyses. Retinal vessel diameters were measured using the IVAN software, and measurements were summarized to central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and arteriole to venule ratio (AVR). Results: The analysis included 1614 subjects. The hypertensive group showed lower values of CRAE (P = 0.033) and AVR (P = 0.0351) compared to the normal blood pressure (BP) group. On the contrary, the group having normal BP under antihypertensive treatment did not have different values compared to the normal BP group. Diastolic BP (per mm Hg) was negatively associated with CRAE (P < 0.0001) and AVR (P < 0.0001), while systolic BP (per mm Hg) was positively associated with CRAE (P = 0.001) and AVR (P = 0.0096). Other factors significantly associated included age, sex, alcohol, smoking, cardiovascular disease history, ophthalmic medication, weight, and IOP; differences were observed in a stratified analysis based on BP medication use. Conclusions: Our study confirms previous reports about the association of age and BP with vessel diameters. The negative correlation between BP and CRAE seems to be guided by the effect of diastolic BP as higher systolic BP is independently associated with higher values of CRAE. The association of BP status with retinal vessel diameters is determined by diastolic BP status in our population. Multiple other factors are also independently associated with retinal vessel diameters

Analysis of CH2_{2}O x OH as marker for fuel-rich air to pure oxy-fuel flames under higher preheat temperature and elevated pressure

The scope of the present work is a numerical and experimental investigation about the range of validity in terms of applicability of CH$_{2}$OxOH as a marker for the heat release rate (HRR) for fuel-rich air to pure oxy-fuel flames including preheating and elevated pressure. Therefore, laminar, freely propagating 1d CH$_{4}$ flames were calculated, where oxygen content in the oxidizer (from air to pure oxy-fuel combustion), inlet temperature and pressure were varied for a wide range of the equivalence ratios. The preheat temperature and pressure were parametrically changed from 300 K to 573 K and 1 bar to 5 bar, respectively. Different reaction mechanisms were used, namely GRI30, DLR, USC/II, Caltech2.3 and ABF. The performance of the CH$_{2}$OxOH as a marker for HRR is assessed in terms of correlation coefficients of their profiles in laminar flames. The comparison of the obtained correlations of CH$_{4}$/air and CH$_{4}$/O$_{2}$ flames shows that in case of air combustion, the HRR can be accurately estimated by the product of CH$_{2}$OxOH for slightly rich flames (Φ = 1.5), whereas the quality of the correlation degrades with increasing equivalence ratio. In contrary, the correlation coefficient increases with higher equivalence ratios in the fuel-rich domain for enhanced oxygen contents in the oxidizer. For pure oxyfuel combustion, the best correlation is found at an equivalence ratio of approximately Φ = 3.0. Elevated pressure leads in all flames to better correlations at lower equivalence ratios compared to standard inlet conditions, whereas preheating induces the opposite trend and expands the valid regime. A series of CH$_{4}$/air flames were also investigated experimentally in a range of the equivalence ratio between 1 < Φ < 2 at standard inlet conditions. The qualitative CH$_{2}$O (excitation at 355 nm) and OH (excitation at 283 nm) concentration were resolved applying two-dimensional LIF for flames stabilized at a McKenna burner. Comparisons show similar trends for measurements and numerical simulations

Pb et As dans des eaux alcalines minières : contamination, comportement et risques (mine abandonnée de Zeïda, Maroc)

Des échantillons d’eau et de matière en suspension ont été prélevés le long de l’oued Moulouya et dans des lacs de carrière au niveau de l’ancien centre minier de Zeïda (Haute Moulouya, Maroc) en vue d’en évaluer la salubrité. Il est en effet important d’établir le degré et les causes éventuelles de dégradation de la qualité de ces eaux, compte tenu de leur usage à des fins tant domestiques qu’agricoles. Des résidus de traitement ont également été échantillonnés dans les haldes abandonnées.L’analyse des distributions et des variations spatio-temporelles des concentrations de Pb et As a permis de mettre en évidence que le centre minier a véritablement un impact sur la qualité des eaux de surface environnantes, malgré le caractère neutre à alcalin du drainage. Aucune ne rejoint les critères de l’Organisation mondiale de la santé en matière de Pb et As dans l’eau potable (10 µg/L), mais près de la moitié souscrit aux normes marocaines (50 µg/L). L’importance de la dégradation varie selon la saison et la localité, et le contraste entre sites a priori non dégradés et sites dégradés n’est pas toujours très prononcé. On observe même des variations à l’inverse des tendances attendues. Les résultats peuvent cependant être réconciliés en tenant compte de l’importance du transport particulaire par rapport au transport dissous au moment et au lieu de l’échantillonnage.Il appert que les minéralisations et les résidus miniers restés sur place peuvent constituer la principale source de pollution des eaux de surface de la région de Zeïda.The Upper Moulouya Basin was the location of extensive lead mining between 1930 and 1985, with three major operations near Aouli, Mibladen and Zeïda. The Moulouya drains about 7.5% of the Moroccan territory and provides drinking and irrigation water to many communities over its more than 500 km path. It is thus important to determine the impact of past mining activities on its water quality, since the mining sites were abandoned with little or no rehabilitation. This paper focuses on the Zeïda area, the uppermost of these mining centres on the Moulouya.About 630,172 t of lead concentrates (40‑70% Pb) were produced between 1972 and 1985 at Zeïda. Lead was mined from carbonate and sulphide mineral deposits (cerussite, 70%; galena, 30%) mixed with barite in stratiform ore bodies hosted by Permo-Triassic arkoses. Mining left 12 Mt and 70 Mt of tailings and wastes in fully exposed piles on each side of the Moulouya, as well as a dozen water-filled open-stopes. Mine drainage is of neutral pH, thanks to the low content of residual sulphide minerals and the availability of carbonate in the tailings and host rock. The river and some quarry-lakes are tapped to fulfill domestic, agricultural and stock-breeding needs. One lake is used to directly feed Zeïda’s water network (pop. 3,000), without any water treatment.The Moulouya, upstream and downstream of Zeïda, and four lakes were sampled twice in 2002 (dry period: February; wet period: April). Temperature, electric conductivity (EC), Eh and pH were measured in the field. Samples were filtered through 0.45 µm membranes. The filtrates were preserved with 4% HNO3 and kept at 4°C until analysis. The filters and their particulate fraction, as well as a composite sample of the tailings, were dried and kept dry until dissolution and analysis. All measurements were performed by ICP-MS and capillary electrophoresis analyses.Lead and arsenic are well above « normal » concentrations in the tailings, at 5,547 g/t and 192 g/t, respectively. These elements are clear threats to population health, since dust from unstabilized tailings can be dispersed by wind and rain waters, contaminating agricultural soils and surface waters, and eventually leading to cases of saturnism or arsenical intoxication in the population. All Pb and As concentrations measured in the waters sampled are above the World Health Organisation criteria for drinking water (10 µg/L for Pb and As). Nevertheless, about half of these measurements meet the Moroccan criteria (50 µg/L). All samples show near neutral or slightly basic pH values (7.2-8.9). EC is also high (> 1,000 µS/cm).As and Pb are largely associated with the particulate fraction (> 80% of total As and Pb), except for As in two lakes (< 40%). Overall, their concentrations are higher in the Zeïda area than upstream in the Moulouya. However, this is a tendency rather than a rule, because the differences are often small (< 50%) and suffer exceptions. For instance, Pb concentrations are 60% lower than the so-called uncontaminated reference station, in two quarry-lakes sampled during the wet period. The occasional lack of significant and consistent contrast between an obviously degraded environment and a pristine site was unexpected. The results were therefore further investigated, in order to identify possible explanations for the apparent discrepancies.Coherency in the data set emerges when one considers the relative importance of dissolved and particulate transport in the various types of environments sampled. Using this interpretation scheme, EC is considered as an indicator of solute transportation, since EC is a function of dissolved ionic components. Total Pb is regarded as an indicator of particulate transportation, since Pb is strongly adsorbed to particulate substrates at the pH observed. Following these assumptions, particulate transport appears to dominate over dissolved transportation in the Moulouya. Total Pb increases by factors of 3.4 and 9.8 from dry to wet periods, whereas EC decreases by 0.7-0.8, as a result of rain dilution. In two of the four lakes, dissolved transport is comparatively more important, since EC does not change significantly and total Pb shows only a small increase from the dry to the wet period. In these lakes, the dissolved input during the rainy period appears to be large enough to keep EC at its previous value, without significant dilution, as opposed to what is going on in the Moulouya. In the two other lakes, both EC and total Pb decrease from the dry to the wet period, pointing to dilution effects greater than either dissolved or particulate mobilization.Apparent discrepancies in the intensity and direction of variations are explained when prevailing modes of dispersion are taken into account. For instance, the enrichment factor of total Pb in the Moulouya, downstream of Zeïda, jumps from 1.1 (dry) to 3.2 (wet), with respect to the reference station. Meanwhile, EC increases only from 1.2 (dry) to 1.5 (wet). The greater increase of total Pb over EC is explained by prevalent particulate transport. In another case, the enrichment of EC with respect to the reference station, in two lakes, increases from 14.2 and 20.4 (dry) to 20.1 and 27.9 (wet) while total Pb enrichment decreases from 2.0 and 2.0 (dry) to 1.6 and 1.3 (wet). Here, the prevalence of dissolved transport in these two lakes, combined with particulate transport at the reference station, allow for a strong increase in the EC parameter, concurrent with a weak increase in total Pb. Finally, in the lakes where both dissolved and particulate transport are presumably minor, total Pb undergoes enrichment with respect to the reference station, in the dry period (by 3.4 and 1.8), whereas depletion characterizes the wet period (0.6 in both lakes). In this case, enrichment is likely the result of evaporation during the dry season, and depletion the result of dilution by rain during the wet period. These two types of lake behave differently because they are located next to residual mineral deposits (likely with more soluble phases), have short travel distances and thus fewer contacts with adsorbing substrates, which is not the case for the other two lakes

Combustion Characterization of Solvents used in Coil Coating Processes: Experiments and Kinetic Modelling

A combined experimental and chemical kinetics modelling approach is presented to account for the combustion behaviour of solvents utilized in coil coating processes. Heating values and laminar burning velocities of typical industrial solvent formulations comprising alcohols, ethers, esters and aromatics are experimentally investigated. Due to the complexity of species participating in the solvent formulations surrogate solvents are introduced, one for each considered formulation. An “in-house” chemical kinetics mechanism has been extended in order to take into account the solvents’ combustion and consists of 321 species participating in 1826 reactions. Its overall performance is validated against the laminar burning velocity measurements. A good qualitative and quantitative reproduction of the experimental curves is depicted with maximum discrepancies observed in the range of 10-15%

A comparative study on the effect of simulated EGR environment on spray characteristics under engine-like conditions

Abstract Increasing concern over air quality and security of energy supply poses challenges to engine research and manufacturing. Despite improvements in conventional engine design, many alternatives are winning their place in order to further reduce engine-out emissions. Sophisticated operating modes, such as homogeneous charge compression ignition (HCCI) and Partially premixed Charge Compression Ignition (PCCI), often coupled with exhaust gas recirculation and/or aftertreatment are employed for regulating nitric oxide (NO x ) and soot emission levels. However, a totally homogeneous mixture is unachievable in practical engines. Inherent inhomogeneities in fuel concentration and temperature may significantly affect the ignition and combustion processes, hence various control strategies attract research interest. The present work demonstrates the potential of emission reduction in Diesel engines operating under high boost conditions through a combination of multi-injection strategies and high EGR schemes

The Decreasing Prevalence of Nonrefractive Visual Impairment in Older Europeans: A Meta-analysis of Published and Unpublished Data

TOPIC: To estimate the prevalence of nonrefractive visual impairment and blindness in European persons 55 years of age and older. CLINICAL RELEVANCE: Few visual impairment and blindness prevalence estimates are available for the European population. In addition, many of the data collected in European population-based studies currently are unpublished and have not been included in previous estimates. METHODS: Fourteen European population-based studies participating in the European Eye Epidemiology Consortium (n = 70 723) were included. Each study provided nonrefractive visual impairment and blindness prevalence estimates stratified by age (10-year strata) and gender. Nonrefractive visual impairment and blindness were defined as best-corrected visual acuity worse than 20/60 and 20/400 in the better eye, respectively. Using random effects meta-analysis, prevalence rates were estimated according to age, gender, geographical area, and period (1991-2006 and 2007-2012). Because no data were available for Central and Eastern Europe, population projections for numbers of affected people were estimated using Eurostat population estimates for European high-income countries in 2000 and 2010. RESULTS: The age-standardized prevalence of nonrefractive visual impairment in people 55 years of age or older decreased from 2.22% (95% confidence interval [CI], 1.34-3.10) from 1991 through 2006 to 0.92% (95% CI, 0.42-1.42) from 2007 through 2012. It strongly increased with age in both periods (up to 15.69% and 4.39% in participants 85 years of age or older from 1991 through 2006 and from 2007 through 2012, respectively). Age-standardized prevalence of visual impairment tended to be higher in women than men from 1991 through 2006 (2.67% vs. 1.88%), but not from 2007 through 2012 (0.87% vs. 0.88%). No differences were observed between northern, western, and southern regions of Europe. The projected numbers of affected older inhabitants in European high-income countries decreased from 2.5 million affected individuals in 2000 to 1.2 million in 2010. Of those, 584 000 were blind in 2000, in comparison with 170 000 who were blind in 2010. CONCLUSIONS: Despite the increase in the European older population, our study indicated that the number of visually impaired people has decreased in European high-income countries in the last 20 years. This may be the result of major improvements in eye care and prevention, the decreasing prevalence of eye diseases, or both

Prevalence of Age-Related Macular Degeneration in Europe: The Past and the Future

Purpose Age-related macular degeneration (AMD) is a frequent, complex disorder in elderly of European ancestry. Risk profiles and treatment options have changed considerably over the years, which may have affected disease prevalence and outcome. We determined the prevalence of early and late AMD in Europe from 1990 to 2013 using the European Eye Epidemiology (E3) consortium, and made projections for the future. Design Meta-analysis of prevalence data. Participants A total of 42 080 individuals 40 years of age and older participating in 14 population-based cohorts from 10 countries in Europe. Methods AMD was diagnosed based on fundus photographs using the Rotterdam Classification. Prevalence of early and late AMD was calculated using random-effects meta-analysis stratified for age, birth cohort, gender, geographic region, and time period of the study. Best-corrected visual acuity (BCVA) was compared between late AMD subtypes; geographic atrophy (GA) and choroidal neovascularization (CNV). Main Outcome Measures Prevalence of early and late AMD, BCVA, and number of AMD cases. Results Prevalence of early AMD increased from 3.5% (95% confidence interval [CI] 2.1%–5.0%) in those aged 55–59 years to 17.6% (95%

Ophthalmology

PURPOSE: To investigate systemic and ocular determinants of peripapillary retinal nerve fiber layer thickness (pRNFLT) in the European population. DESIGN: Cross-sectional meta-analysis. PARTICIPANTS: A total of 16 084 European adults from 8 cohort studies (mean age range, 56.9+/-12.3-82.1+/-4.2 years) of the European Eye Epidemiology (E3) consortium. METHODS: We examined associations with pRNFLT measured by spectral-domain OCT in each study using multivariable linear regression and pooled results using random effects meta-analysis. MAIN OUTCOME MEASURES: Determinants of pRNFLT. RESULTS: Mean pRNFLT ranged from 86.8+/-21.4 mum in the Rotterdam Study I to 104.7+/-12.5 mum in the Rotterdam Study III. We found the following factors to be associated with reduced pRNFLT: Older age (beta = -0.38 mum/year; 95% confidence interval [CI], -0.57 to -0.18), higher intraocular pressure (IOP) (beta = -0.36 mum/mmHg; 95% CI, -0.56 to -0.15), visual impairment (beta = -5.50 mum; 95% CI, -9.37 to -1.64), and history of systemic hypertension (beta = -0.54 mum; 95% CI, -1.01 to -0.07) and stroke (beta = -1.94 mum; 95% CI, -3.17 to -0.72). A suggestive, albeit nonsignificant, association was observed for dementia (beta = -3.11 mum; 95% CI, -6.22 to 0.01). Higher pRNFLT was associated with more hyperopic spherical equivalent (beta = 1.39 mum/diopter; 95% CI, 1.19-1.59) and smoking (beta = 1.53 mum; 95% CI, 1.00-2.06 for current smokers compared with never-smokers). CONCLUSIONS: In addition to previously described determinants such as age and refraction, we found that systemic vascular and neurovascular diseases were associated with reduced pRNFLT. These may be of clinical relevance, especially in glaucoma monitoring of patients with newly occurring vascular comorbidities

Flows in a model furnace and heat exchanger

Imperial Users onl