Fifteen years follow-up of photorefractive keratectomy up to 10 D of myopia: outcomes and analysis of the refractive regression

PURPOSE: To evaluate outcomes of photorefractive keratectomy up to -10.00 D of myopia and -4.50 of astigmatism and to develop a predictive model for the refractive changes in the long term. SETTING: Vissum Corporation and Miguel Hernandez University (Alicante, Spain). DESIGN: Retrospective-prospective observational series of cases. METHODS: This study included 33 eyes of 33 patients aged 46.79±7.04 years (range 40-57) operated with the VISX 20/20 excimer laser with optical zones of 6 mm. No mitomycin C was used in any of these cases. The minimum follow-up was 15 years. The main outcome measures were: uncorrected and corrected distance visual acuity, manifest refraction and corneal topography. Linear regression models were developed from the observed refractive changes over time. RESULTS: Safety and efficacy indexes at 15 years were 1.18 and 0.83, respectively. No statistically significant differences were detected for any keratometric variable during the follow-up (p≥0.103). 15 years after the surgery 54.55% of the eyes were within ±1.00 D of spherical equivalent and 84.85% within ±2.00 D. The uncorrected distance visual acuity at 15 years was 20/25 or better in 60.6% of the eyes and 20/40 or better in 72.73% of the eyes. The correlation between the attempted and the achieved refractions was r=0.948 (p<0.001) at 1 year, and r=0.821 (p<0.001) at 15 years. No corneal ectasia was detected in any case during the follow-up. CONCLUSIONS: Photorefractive keratectomy is a safe refractive procedure in the long term within the range of myopia currently considered suitable for its use, although its efficacy decreases with time, especially, in high myopia. The model developed predicts a myopic regression of 2.00 D at 15 years for an ablation depth of 130 µm

Considerations on the effects of automotive lighting to enhance alert and avoid sleepiness in night time drivers via melatonin inhibition

The effects of light on circadian rhythms have been known for a long time. It is well known that shift workers, transoceanic travellers and other people being exposed to light during their sleep hours have remarkable disorders in their biological clocks that can last just some days with few important effects or become really serious with higher incidence of serious diseases. One of the reasons for circadian clock to be altered is the melatonin inhibition, due to the exposure to intense and/or bluer lights during sleep hours. The inhibition of the secretion of this neurohormone has been proven to be an effective measure to enhance alert and avoid sleepiness. However, although this sleepiness avoidance is widely used in indoor illumination to achieve better productivities or higher concentration in mental tasks, nothing has been done in order to ensure that night time drivers will keep awake during long journeys via melatonin inhibition. In this sense, the lighting of the own vehicle could be the most reasonable candidate to avoid sleepiness on this collective with the consequent impact on safety. This work uses the theoretical models of dependence between light intensity and wavelength and melatonin inhibition to analyze the potential influence of car headlamps on sleepiness in people driving during long periods at night-time. The results of this research show that cars equipped with headlamps using xenon and halogen light sources, which are the most common with a still wide advantage on LEDs cause no melatonin inhibition on people driving during long periods at night and thus, the current automotive lighting technology cannot avoid distraction and sleepiness in drivers with this strategy. However, a new lighting pattern that theoretically would cause melatonin inhibition and hence, an enhanced road safety, is proposed. We conclude that the incorporation of headlighting systems providing this pattern would be extremely positive for road safety and one important step for the automotive industr

Materiales didácticos de filosofía helenística

Memoria ID-083. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2018-2019

Materiales docentes de asignaturas de historia de la filosofía adaptados al espacio europeo de educación superior

Memoria ID12-0014. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2012-2013

Materiales didácticos para la docencia presencial y virtual de la filosofía antigua

Memoria ID-0086. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2016-2017

Materiales docentes de asignaturas de Historia de la Filosofía adaptados al Espacio Europeo de Educación Superior

Memoria ID-0250. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015

Post-Ugi transformations for the access to pyrrolobenzodiazepine scaffolds with different degrees of unsaturation

The synthesis of three novel families of pyrrolo[2,1-c][1,4]benzodiazepine-5-ones is described. The compounds were prepared according to a three-step sequence, involving an Ugi reaction, building of the pyrrolo nucleus, and reduction–cyclization to the corresponding diazepine. Depending on the amine employed in the synthesis of the Ugi adducts, different unsaturation degrees could be obtained in the pyrrolo ring (saturated or with endo or exo unsaturations), a key feature determining their biological activity, as it affects the affinity of the pyrrolobenzodiazepines toward DNA and thus their cytotoxicity. This synthetic methodology represents a significant improvement with respect to those described in the literature so far, as it uses inexpensive and commercially available starting materials without needing derivatization or the use of protecting groups.Consejería de Educación de la Junta de Castilla y León (project BU075G19

Cobertura de la señal TDT DBV-T2 en zonas rurales

This paper analyzes the Digital Terrestrial Television (DTT) signal coverage in the department of Cundinamarca, comparing two propagation models: Okumura-Hata, and Stanford University Interim (SUI). These models were selected because they allow the calculation of propagation losses in the UHF band and do not require greater precision in the cartographic information to estimate diffraction losses. As a result, was obtained that the selected models are close to the field measurements, in a range of 8 to 12 dB. In addition, adjustments were made to the propagation models obtaining the losses estimation in the signal propagation. The models were evaluated applying statistical criteria such as: correlation coefficient, mean square error and standard deviation. Finally, it was determined that the two models fit easily to the values obtained in the field measurements; however, the difference presented by the Okumura-Hata model was smaller in comparison with the SUI model; but the latest one allowed a better fit to the propagation model than the Okumura-Hata model.En este artículo se realiza el análisis de cobertura de la señal de Televisión Digital Terrestre (TDT) en el departamento de Cundinamarca, comparando dos modelos de propagación: Okumura-Hata, e Interino de la Universidad de Stanford (SUI). Estos modelos fueron seleccionados debido a que permiten calcular las pérdidas de propagación en la banda UHF y no requieren mayor precisión en la información cartográfica para estimar las pérdidas por difracción. Como resultado se obtuvo que los modelos seleccionados se acercan&nbsp;&nbsp; al valor obtenido, en las mediciones de campo, en un rango de 8 a 12 dB. Adicionalmente, se efectuaron ajustes a los modelos de propagación obteniendo la estimación de pérdidas en la propagación de la señal. Los modelos se evaluaron aplicando criterios estadísticos como: coeficiente de correlación, error medio cuadrado y desviación estándar Finalmente, se determinó que los dos modelos se ajustan fácilmente a los valores obtenidos en las mediciones de campo; sin embargo, la diferencia presentada por el modelo Okumura-Hata resultó menor en comparación con el modelo SUI; pero este último permitió realizar un mejor ajuste al modelo de propagación que el modelo Okumura-Hata

Microstructural quantification of collagen fiber orientations and its integration in constitutive modeling of the porcine carotid artery

Background Mechanical characteristics of vascular tissue may play a role in different arterial pathologies, which, amongst others, requires robust constitutive descriptions to capture the vessel wall’s anisotropic and non-linear properties.Specifically, the complex 3D network of collagen and its interaction with other structural elements has a dominating effect of arterial properties at higher stress levels.The aim of this study is to collect quantitative collagen organization as well as mechanical properties to facilitate structural constitutive models for the porcine carotid artery.This helps the understanding of the mechanics of swine carotid arteries, being a standard in clinical hypothesis testing, in endovascular preclinical trials for example. Method Porcine common carotid arteries (n = 10) were harvested and used to (i) characterize the collagen fiber organization with polarized light microscopy, and (ii) the biaxial mechanical properties by inflation testing.The collagen organization was quantified by the Bingham orientation density function (ODF), which in turn was integrated in a structural constitutive model of the vessel wall.A one-layered and thick-walled model was used to estimate mechanical constitutive parameters by least-square fitting the recorded in vitro inflation test results.Finally, uniaxial data published elsewhere were used to validate the mean collagen organization described by the Bingham ODF. Results Thick collagen fibers, i.e.the most mechanically relevant structure, in the common carotid artery are dispersed around the circumferential direction.In addition, almost all samples showed two distinct families of collagen fibers at different elevation, but not azimuthal, angles.Collagen fiber organization could be accurately represented by the Bingham ODF (¿1,2,3=[13.5,0.0,25.2] and ¿1,2,3=[14.7,0.0,26.6]; average error of about 5%), and their integration into a structural constitutive model captured the inflation characteristics of individual carotid artery samples.Specifically, only four mechanical parameters were required to reasonably (average error from 14% to 38%) cover the experimental data over a wide range of axial and circumferential stretches.However, it was critical to account for fibrilar links between thick collagen fibers.Finally, the mean Bingham ODF provide also good approximation to uniaxial experimental data. Conclusions The applied structural constitutive model, based on individually measured collagen orientation densities, was able to capture the biaxial properties of the common carotid artery. Since the model required coupling amongst thick collagen fibers, the collagen fiber orientations measured from polarized light microscopy, alone, seem to be insufficient structural information. Alternatively, a larger dispersion of collagen fiber orientations, that is likely to arise from analyzing larger wall sections, could have had a similar effect, i.e. could have avoided coupling amongst thick collagen fibers.Peer ReviewedPostprint (author's final draft