Phase change material (PCM) offers high-density thermal energy storage, making it attractive for thermal management applications of electronic circuitry and thermal energy storage. However, PCM, like ...paraffin wax, ideal for such low-temperature applications, has very low thermal conductivity. The present study focused on the improvement of the thermal conductivity of paraffin wax using surfactants. The surfactants used as thermal conductivity enhancers (TCE) are cetyltrimethyl ammonium bromide (CTAB), Dioctyl sodium sulfosuccinate (known as AOT) and sodium dodecyl sulfate (SDS). The surfactant self-aggregation called a micelle, acts as conducting medium inside the paraffin wax, providing better thermal conductivity. The highest heat transfer rate with a peak temperature of 71 °C was observed in the case of AOT micelle paraffin wax. Adding SDS, CTAB, and AOT surfactants increased the highest temperatures by 4%, 8.4%, and 18.33% compared to pure PCM.
Ruling out glaucoma in myopic eyes often poses a diagnostic challenge because of atypical optic disc morphology and visual field defects that can mimic glaucoma. We determined whether neuroretinal ...rim assessment based on Bruch's membrane opening (BMO), rather than conventional optic disc margin (DM)-based assessment or retinal nerve fiber layer (RNFL) thickness, yielded higher diagnostic accuracy in myopic patients with glaucoma.
Case-control, cross-sectional study.
Myopic patients with glaucoma (n = 56) and myopic normal controls (n = 74).
Myopic subjects with refraction error greater than -2 diopters (D) (spherical equivalent) and typical myopic optic disc morphology, with and without glaucoma, were recruited from a glaucoma clinic and a local optometry practice. The final classification of myopic glaucoma or myopic control was based on consensus assessment by 3 clinicians of visual fields and optic disc photographs. Participants underwent imaging with confocal scanning laser tomography for measurement of DM rim area (DM-RA) and with spectral domain optical coherence tomography (SD OCT) for quantification of a BMO-based neuroretinal rim parameter, minimum rim width (BMO-MRW), and RNFL thickness.
Sensitivity of DM-RA, BMO-MRW, and RNFL thickness at a fixed specificity of 90% and partial area under the curves (pAUCs) for global and sectoral parameters for specificities ≥90%.
Sensitivities at 90% specificity were 30% for DM-RA and 71% for both BMO-MRW and RNFL thickness. The pAUC was higher for the BMO-MRW compared with DM-RA (P < 0.001), but similar to RNFL thickness (P > 0.5). Sectoral values of BMO-MRW tended to have a higher, but nonsignificant, pAUC across all sectors compared with RNFL thickness.
Bruch's membrane opening MRW is more sensitive than DM-RA and similar to RNFL thickness for the identification of glaucoma in myopic eyes and offers a valuable diagnostic tool for patients with glaucoma with myopic optic discs.
Flood forecasting in a transboundary river basin is challenging due to insufficient data sharing between countries in the upper and lower reaches of a basin. A solution is the use of ...satellite-observed rainfall and numerical weather prediction (NWP) for hydrological forecasting. We applied this method to the transboundary sparsely gauged Chenab River basin in Pakistan and India to reproduce the exceptionally high flood in 2014. We employed global NWPs by three weather centers to consider forecast uncertainty and downscaled them using the Weather Research and Forecasting (WRF) Model to prepare precipitation inputs. For hydrological simulations, we used a kinematic wave model, the Integrated Flood Analysis System (IFAS), for the upper-reach basin with high mountains and steep slopes, and we used a diffusive-wave rainfall–runoff–inundation (RRI) model for low altitudes and mild slopes. In our forecasting experiment, the precipitation by the global NWP was not able to predict flood peaks consistently. However, the downscaled rainfall by regional NWP showed good performance in predicting flood waves quantitatively, and a multimodel approach provided added value in issuing reliable warning as early as 6 days in advance. A confident streamflow forecasting near the border of the countries also led to reliable inundation forecasting by the RRI model in the lower-reach basin.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Remote sensing precipitation or precipitation from numerical weather prediction (NWP) is considered to be the best substitute for in situ ground observations for flood simulations in transboundary, ...data-scarce catchments. This research was aimed to evaluate the possibility of using a combination of a satellite precipitation product and NWP precipitation for better flood forecasting in the transboundary Chenab River Basin (CRB) in Pakistan. The gauge-calibrated satellite precipitation product, i.e., Global Satellite Mapping of Precipitation (GSMaP_Gauge), was selected to calibrate the Integrated Flood Analysis System (IFAS) model for the 2016 flood event in the Chenab River at the Marala Barrage gauging site in Pakistan. Precipitation from the Global Forecast System (GFS) NWP, with nine different lead times up to 4 days, was used in the calibrated IFAS model to predict the flood hydrograph in the Chenab River. The hydrologic simulations, with global GFS forecasts, were unable to predict the flood peak for all lead times. Then, the Weather Research and Forecasting (WRF) model was used to downscale the precipitation forecasts with one-way and two-way nesting approaches. In the WRF model, the CRB was centered in two domains of 25 km and 5 km resolutions. The downscaled precipitation forecasts were subsequently supplied to the IFAS model, and the predicted simulations were compared to obtain the optimal flood peak simulation in the Chenab River. It was found in this study that the simulated hydrographs, at different lead times, from the precipitation of two-way WRF nesting exhibited superior performance with the highest R2 and Nash–Sutcliffe efficiency (NSE) and the lowest percent bias (PBIAS) compared with one-way nesting. Moreover, it was concluded that the combination of GFS forecast and two-way WRF nesting can provide high-quality precipitation prediction to simulate flood hydrographs with a remarkable lead time of 96 h when applying coupled hydrometeorological flow simulation.
To determine the rate of glaucomatous visual field change in routine clinical care.
Mean deviation (MD) rate was computed in one randomly selected eye of all glaucoma patients and suspects with ≥5 ...examinations in a tertiary eye-care center. Proportions of "fast" (MD rate, <-1 to -2 dB/y) and "catastrophic" (<-2 dB/y) progressors were determined. The MD rates were computed in tertile groups by the number of examinations, baseline age, and MD. The MD rates were compared to the Canadian Glaucoma Study (CGS), a prospective study with IOP interventions mandated by visual field progression, by pairwise matching of patients by baseline MD.
There were 2324 patients with median (interquartile range) baseline age and MD of 65 (56, 74) years and -2.44 (-5.44, -0.86) dB, and follow-up of 7.1 (4.8, 10.2) years with 8 (6, 11) examinations. The median MD rate was -0.05 (0.13, -0.30) dB/y, while the mean follow-up IOP was 17.1 (15.0, 19.7) mm Hg. The MD rate was progressively worse, with a doubling of fast and catastrophic progressors, with each tertile of increasing age. Worse MD rate was associated with lower follow-up IOP. Neither MD rate nor the number of fast and catastrophic progressors was significantly different in clinical care patients matched to CGS patients.
Most patients under routine glaucoma care demonstrate slow rates of visual field progression. The MD rate in the current study was similar to an interventional prospective study, but considerably less negative compared to published studies with similar design.
Many studies have assessed structure-function relations in glaucoma, but most without topographical comparison across the central 30°. We present a method for assessing structure-function relations ...with en face images of retinal nerve fiber layer (RNFL) bundles allowing topographical comparison across much of this retinal area. Forty-four patients with glaucoma (median age 61 years) were recruited and tested with Optical Coherence Tomography (OCT) and perimetry. Six rectangular volume scans were gathered, and then montaged to provide en face views of the RNFL bundles. We calculated the proportion of locations showing a perimetric defect that also showed an en face RNFL defect; and the proportion of locations falling on an RNFL defect that also showed a perimetric defect. A perimetric defect for a location was defined as a total deviation (TD) value equal to or deeper than -4 dB. We found that the median (IQR) number of locations with abnormal RNFL bundle reflectance that also had abnormal TD was 78% (60%) and for locations with abnormal TD that also had abnormal RNFL bundle reflectance was 75% (44%). We demonstrated a potential approach for structure-function assessment in glaucoma by presenting a topographic reflectance map, confirming results of previous studies and including larger retinal regions.
•LiTaO3-modified BiFeO3–BaTiO3 dielectric ceramics were prepared.•Easy and reproducible solid state reaction method was used.•Temperature stable dielectric of 5000 ± 9.5% was achieved in the range ...250–450 °C.
LiTaO3 (LT)-modified (1 − x)(0.675BiFeO3–0.325BaTiO3) + 0.6 mol% MnO2 + 0.4 mol% CuO (BFBTMC–xLT, where x = 0–0.030) ceramics were synthesized by solid state reaction method. The crystal symmetry, ferroelectric response, and temperature stable dielectric properties were investigated as a function of different LT-content. The X-ray diffraction study of BFBTMC–LT piezoceramics revealed no remarkable variation in the crystal symmetry. The value of maximum polarization (Pm ≈ 24 μC/cm2) and remnant polarization (Pr ≈ 18 μC/cm2) were obtained at BFBTMC–0.010LT composition. The maximum temperature of permittivity (Tmax) decreased by the addition of LT-content in BFBTMC materials. The un-doped sample was ferroelectric; a change to relaxor behavior occurred by the addition of LT-content, with broad frequency dependent curves of dielectric mid-value permittivity (εrmid) and tangent loss as a function of temperature. A significant enhancement occurred at 3 mol% LT-modified BFBTMC ceramics, with εrmid = 5000 ± 9.5% (250–450 °C at 1 kHz). These results are favorable for practical applications in high temperature dielectrics.
An understanding of the relationship between functional and structural measures in primary open‐angle glaucoma is necessary for both grading the severity of disease and for understanding the natural ...history of the condition. This article outlines the current evidence for the nature of this relationship and highlights the current mathematical models linking structure and function. Large clinical trials demonstrate that both structural and functional change are apparent in advanced stages of disease, and at an individual level, detectable structural abnormality may precede functional abnormality in some patients, whereas the converse is true in other patients. Although the exact nature of the ‘structure–function’ relationship in primary open‐angle glaucoma is still the topic of scientific debate and the subject of continuing research, this article aims to provide the clinician with an understanding of the past concepts and contemporary thinking in relation to the structure–function relationship in primary open‐angle glaucoma.
Evaluation of progressive visual field (VF) damage is often based on pointwise sensitivity data from standard automated perimetry; however, frequency-of seeing and test-retest studies demonstrate ...that these measurements can be highly variable, especially in areas of damage. The aim of this study was to characterize VF variability by the level of sensitivity using a statistical method to quantify heteroscedasticity.
A total of 14,887 Humphrey 24-2 SITA Standard VFs from 2736 patients (2736 eyes) attending Moorfields Eye Hospital from 1997 to 2009 were studied retrospectively. The VF series of each eye was analyzed using pointwise linear regression of sensitivity over time, with residuals (difference from fitted-value) from each regression pooled according to both observed and fitted sensitivities.
The median (interquartile range) patient age, follow-up, and series length was 64 (54-71) years, 5.5 (3.9-7.0) years, and 6 (5-7) VFs, respectively. The inferred variability as a function of fitted-sensitivity was in good agreement with previous estimates. Variability was also described as a function of measured sensitivity, which confirmed that variability increased rapidly as the observed sensitivity decreased.
This study highlights a new approach for characterizing VF variability by the level of sensitivity. A considerable strength of the method is that inference is based on thousands of clinic patients rather than the tens of subjects in test-retest studies. The results can help distinguish real VF progression from measurement variability and will be used in models for glaucoma progression detection.
PRéCIS:In this case-control study, female sex, and older age were risk factors for tube exposure; risk was related to the number of prior ocular surgeries and scleral patch graft (compared with ...pericardial graft) was found to protect against exposure.
PURPOSE:Identification of potential risk factors for glaucoma drainage device (GDD) exposure may help to prevent this potentially blinding complication. The purpose of this study was to evaluate the possible risk factors for GDD exposure in a tertiary eye care center in the Middle-East.
METHODS:A retrospective case-control study was undertaken for a 7-year period (2008 to 2015 inclusive). All patients who presented with a GDD incident exposure were identified and were compared with a similar number of controls (without exposure) identified during the same period. Demographic factors, past ocular history, treatment, and surgical technique were recorded for both groups. Bivariate and multivariable analyses were used to identify possible risk factors for tube exposure.
RESULTS:A total of 836 patients underwent GDD surgery during this time period and 53 patients were identified with exposure, giving a cumulative incident exposure rate of 6.3% (0.9% per year). Bivariate analysis showed that the median age of cases (51 years) was similar to controls (53 years) (P=0.95), while there was a greater proportion of women with exposure (49%) compared with the control group (28%) with a statistically significant difference (P=0.028). The number of previous surgeries (3.77±2.1) was significantly higher (P=0.018) in the exposure group (4.25±2.0) compared with controls (3.3±2.0). With each unit increase in the number of previous surgeries, the odds of exposure significantly increased by 1.29 (95% confidence interval, 1.05-1.57). In the multivariable regression, female sex (P=0.006) and older age (P=0.025) were significant risk factors and use of a scleral patch (P=0.02) graft potentially protective.
CONCLUSIONS:Previous surgery, female sex, and older age are potential risk factors identified in our study. The use of scleral patch graft is potentially protective against GDD extrusion. Further study is needed to elucidate the reasons for these causative and protective factors.
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