424 research outputs found

    Visual acuity of pseudophakic patients predicted from in-vitro measurements of intraocular lenses with different design

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    The optical quality of a set of IOLs (modeling set: one monofocal and two bifocals) was assessed through focus by the area under the modulation transfer function (MTFa) metric and related to the visual acuity (VA) defocus curves of pseudophakic patients implanted with said IOLs. A non-linear relationship between the MTFa and clinical VA was obtained with an asymptotic limit found to be the best VA achievable by the patients. Two mathematical fitting functions between clinical VA and MTFa were derived with high correlation coefficients (R-2 >= 0.85). They were applied to the MTFa obtained from a different set of IOLs with advanced designs (trial set: one extended range of vision -ERV-, one trifocal ERV and one trifocal apodized) to predict VA versus defocus of patients implanted with these IOLs. Differences between the calculated VA and the clinical VA for both fitting models were within the standard deviation of the clinical measurements in the range of -3.00 D to 0.00 D defocus. thus proving the suitability of the MTFa metric to predict clinical VA performance of new IOL designs. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

    Immigrant students in Spain compared to spanish students: perceived relationships and academic results

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    [Abstract] Personal relationships are central to adolescent students' lives, not just the relationships in which they themselves are involved but also those that unfold around them. This study considers immigrant and Spanish adolescents’ views about the “community dimension of school climate”, centered on family-school relationships and school relationships, and how these relate to their academic results. Seven hundred and forty-five (745) students living in Galicia, Spain, participated in the study. Their ages ranged from 12 to 18 years old (M = 14.5, SD = 1.67). Spanish students accounted for 81% of the sample, while 19% were immigrant students. There were statistical differences between Spanish and immigrant students in their perceived family-school relationships, however this did not impact significantly on their academic results. For immigrant students, the sole variable “school relationships” accounted for 20% of their academic results. For Spanish students, this variable together with students’ age and parental education accounted for 27% of their marks. Results emphasize the relational impact of the perceived processes going on inside the schools and point at the importance that investing in school relationships might have in students, especially when they are immigrants.[Resumen] Las relaciones interpersonales ocupan un lugar central en la vida de los adolescentes, no solo aquellas en las que ellos están implicados sino las que se producen a su alrededor. Este estudio considera su percepción de la “dimensión comunitaria del clima escolar”, centrada en las relaciones familia-escuela y las relaciones escolares, y su papel en los resultados escolares. Participaron 745 alumnos residentes en Galicia, España. Sus edades oscilaban entre los 12 y los 18 años (M = 14.5, DE =1.67). Los alumnos españoles constituían el 81% de la muestra mientras que un 19% eran inmigrantes. Se hallaron diferencias estadísticamente significativas entre los alumnos españoles e inmigrantes en su percepción de las relaciones familia-escuela, aunque estos datos no fueron significativos para los resultados escolares. En la muestra inmigrante, la variable “relaciones escolares” explicaba un 20% de sus resultados escolares. Para los estudiantes españoles, esta variable junto con su edad y el nivel educativo de sus padres y madres explicaban el 27% de sus calificaciones. Los resultados enfatizan el impacto relacional de los procesos percibidos dentro de la escuela y apuntan a la importancia de invertir en la mejora de dichas relaciones, sobre todo cuando los alumnos son inmigrantes

    Finding robust solutions for constraint satisfaction problems with discrete and ordered domains by coverings

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    Constraint programming is a paradigm wherein relations between variables are stated in the form of constraints. Many real life problems come from uncertain and dynamic environments, where the initial constraints and domains may change during its execution. Thus, the solution found for the problem may become invalid. The search forrobustsolutions for constraint satisfaction problems (CSPs) has become an important issue in the ¿eld of constraint programming. In some cases, there exists knowledge about the uncertain and dynamic environment. In other cases, this information is unknown or hard to obtain. In this paper, we consider CSPs with discrete and ordered domains where changes only involve restrictions or expansions of domains or constraints. To this end, we model CSPs as weighted CSPs (WCSPs) by assigning weights to each valid tuple of the problem constraints and domains. The weight of each valid tuple is based on its distance from the borders of the space of valid tuples in the corresponding constraint/domain. This distance is estimated by a new concept introduced in this paper: coverings. Thus, the best solution for the modeled WCSP can be considered as a most robust solution for the original CSP according to these assumptionsThis work has been partially supported by the research projects TIN2010-20976-C02-01 (Min. de Ciencia e Innovacion, Spain) and P19/08 (Min. de Fomento, Spain-FEDER), and the fellowship program FPU.Climent Aunés, LI.; Wallace, RJ.; Salido Gregorio, MA.; Barber Sanchís, F. (2013). Finding robust solutions for constraint satisfaction problems with discrete and ordered domains by coverings. Artificial Intelligence Review. 1-26. https://doi.org/10.1007/s10462-013-9420-0S126Climent L, Salido M, Barber F (2011) Reformulating dynamic linear constraint satisfaction problems as weighted csps for searching robust solutions. 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    Role of color doppler imaging in early diagnosis and prediction of progression in glaucoma

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    This longitudinal and prospective study analyzes the ability of orbital blood flow measured by color Doppler imaging (CDI) to predict glaucoma progression in patients with glaucoma risk factors. Patients with normal perimetry but having glaucoma risk factors and patients in the initial phase of glaucoma were prospectively included in the study and divided, after a five-year follow-up, into two groups: “Progression” and “No Progression” based on the changes in the Moorfields regression analysis (MRA) classification of Heidelberg retina tomograph (HRT). An orbital CDI was performed in all patients and the parameters obtained were correlated with changes in HRT. A logistic discrimination function (LDF) was calculated for ophthalmic artery (OA) and central retinal artery (CRA) parameters. Receiver operating characteristics curves (ROC) were used to assess the usefulness of LDFs to predict glaucomatous progression. A total of 71 eyes were included. End-diastolic velocity, time-averaged velocity, and resistive index in the OA and CRA were significantly different ( ) between the Progression and No Progression groups. The area under the ROC curves calculated for both LDFs was of 0.695 (OA) and 0.624 (CRA). More studies are needed to evaluate the ability of CDI to perform early diagnosis and to predict progression in glaucoma in eyes

    Comparison of visual and optical quality of monofocal versus multifocal intraocular lenses

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    Objective: To compare visual quality in patients implanted with Tecnis ® monofocal (ZCB00) and multifocal (ZMB00) intraocular lenses taking into account their optical quality measured in vitro with an eye model. Methods: In total, 122 patients participated in this study: 44 implanted with monofocal and 78 with multifocal intraocular lenses. Measurements of visual acuity and contrast sensitivity were performed. The optical quality of the intraocular lenses was evaluated in three image planes (distance, intermediate and near) using an eye model on a test bench. The metric considered was the area under the curve of the modulation transfer function. Results: Optical quality at the far focus of the monofocal intraocular lens (area under the curve of the modulation transfer function = 66.97) was considerably better than that with the multifocal lens (area under the curve of the modulation transfer function = 32.54). However, no significant differences were observed between groups at the distance-corrected visual acuity. Distance-corrected near vision was better in the multifocal (0.15 ± 0.20 logMAR) than that in the monofocal group (0.43 ± 0.21 logMAR, p < 0.001), which correlated with the better optical quality at near reached by the multifocal intraocular lens (area under the curve of the modulation transfer function = 29.11) in comparison with the monofocal intraocular lens (area under the curve of the modulation transfer function = 5.0). In intermediate vision, visual acuity was 0.28 ± 0.16 logMAR (multifocal) and 0.36 ± 0.14 logMAR (monofocal) with p = 0.014, also in good agreement with the values measured in the optical quality (area under the curve of the modulation transfer function = 10.69 (multifocal) and 8.86 (monofocal)). The contrast sensitivity was similar in almost all frequencies. Pelli–Robson was slightly better in the monofocal (1.73) than in the multifocal group (1.64; p = 0.023). Conclusion: Patients implanted with multifocal ZMB00 achieved a distance visual acuity similar to those implanted with monofocal ZCB00, but showed significantly better intermediate and near visual acuity. A correlation was found between intraocular lenses’ optical quality and patients’ visual acuity. Contrast sensitivity was very similar between the multifocal and monofocal groups

    Reducing chaos in SAT-like search: finding solutions close to a given one

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    Motivated by our own industrial users, we attack the following challenge that is crucial in many practical planning, scheduling or timetabling applications. Assume that a solver has found a solution for a given hard problem and, due to unforeseen circumstances (e.g., rescheduling), or after an analysis by a committee, a few more constraints have to be added and the solver has to be re-run. Then it is almost always important that the new solution is “close” to the original one. The activity-based variable selection heuristics used by SAT solvers make search chaotic, i.e., extremely sensitive to the initial conditions. Therefore, re-running with just one additional clause added at the end of the input usually gives a completely different solution. We show that naive approaches for finding close solutions do not work at all, and that solving the Boolean optimization problem is far too inefficient: to find a reasonably close solution, state-of-the-art tools typically require much more time than was needed to solve the original problem. Here we propose the first (to our knowledge) approach that obtains close solutions quickly. In fact, it typically finds the optimal (i.e., closest) solution in only 25% of the time the solver took in solving the original problem. Our approach requires no deep theoretical or conceptual innovations. Still, it is non-trivial to come up with and will certainly be valuable for researchers and practitioners facing the same problem.Postprint (published version

    Influence of ocular biometric factors on the defocus curve in an enlarged depth-of-focus intraocular lens

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    Background: To assess the influence of biometric measurements on the defocus curve after the implantation of enlarged depth-of-focus (EDoF) intraocular lens (IOL). Methods: Patients who underwent cataract surgery with bilateral implantation of Tecnis Symfony IOL were enrolled. Preoperatively, axial length (AL), corneal keratometry (K), pupil size and corneal aberrations were measured. 1 month after surgery, distance, intermediate, and near visual acuities (VA) were recorded. At 3 months, monocular and binocular corrected contrast sensitivities under photopic and mesopic lighting conditions were measured with CSV-1000E test. At 6-months, the defocus curve between −5.00 to + 3.00 diopters (D) was assessed in steps of 0.50 D, and NEI-RQL-42 questionnaire was administered. Results: One hundred thirty one eyes of 66 patients were included. Binocular logMAR VA better than 0.1 for intermediate vision was obtained in 90% of patients, whereas only 17.7% obtained that result in near vision. The rate of satisfaction was high (96%) and most of them (85.5%) had no or little difficulties in near vision. The mean amplitude of the defocus curve was 2.35D ± 0.73D, and smaller AL, smaller pupils, younger age, and male sex were associated with wider range of clear vision. Conclusions: Tecnis Symfony IOL enables functional vision at all distances, but demographic variables and preoperative biometric measurements like AL and pupil size influence the postoperative amplitude of the defocus curve. These parameters could be used to predict the performance of EDoF IOLs

    In Vitro Antibacterial Activity of Silver Nanoparticles Conjugated with Amikacin and Combined with Hyperthermia against Drug-Resistant and Biofilm-Producing Strains

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    Antibacterial activity; Biofilms; Silver nanoparticlesActividad antibacteriana; Biopelículas; Nanopartículas de plataActivitat antibacteriana; Biopel·lícules; Nanopartícules de plataIn view of the current increase and spread of antimicrobial resistance (AMR), there is an urgent need to find new strategies to combat it. This study had two aims. First, we synthesized highly monodispersed silver nanoparticles (AgNPs) of approximately 17 nm, and we functionalized them with mercaptopoly(ethylene glycol) carboxylic acid (mPEG-COOH) and amikacin (AK). Second, we evaluated the antibacterial activity of this treatment (AgNPs_mPEG_AK) alone and in combination with hyperthermia against planktonic and biofilm-growing strains. AgNPs, AgNPs_mPEG, and AgNPs_mPEG_AK were characterized using a suite of spectroscopy and microscopy methods. Susceptibility to these treatments and AK was determined after 24 h and over time against 12 clinical multidrug-resistant (MDR)/extensively drug-resistant (XDR) isolates of Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The efficacy of the treatments alone and in combination with hyperthermia (1, 2, and 3 pulses at 41°C to 42°C for 15 min) was tested against the same planktonic strains using quantitative culture and against one P. aeruginosa strain growing on silicone disks using confocal laser scanning microscopy. The susceptibility studies showed that AgNPs_mPEG_AK was 10-fold more effective than AK alone, and bactericidal efficacy after 4, 8, 24, or 48 h was observed against 100% of the tested strains. The combination of AgNPs_mPEG_AK and hyperthermia eradicated 75% of the planktonic strains and exhibited significant reductions in biofilm formation by P. aeruginosa in comparison with the other treatments tested, except for AgNPs_mPEG_AK without hyperthermia. In conclusion, the combination of AgNPs_mPEG_AK and hyperthermia may be a promising therapy against MDR/XDR and biofilm-producing strains. IMPORTANCE Antimicrobial resistance (AMR) is one of the greatest public health challenges, accounting for 1.27 million deaths worldwide in 2019. Biofilms, a complex microbial community, directly contribute to increased AMR. Therefore, new strategies are urgently required to combat infections caused by AMR and biofilm-producing strains. Silver nanoparticles (AgNPs) exhibit antimicrobial activity and can be functionalized with antibiotics. Although AgNPs are very promising, their effectiveness in complex biological environments still falls below the concentrations at which AgNPs are stable in terms of aggregation. Thus, improving the antibacterial effectiveness of AgNPs by functionalizing them with antibiotics may be a significant change to consolidate AgNPs as an alternative to antibiotics. It has been reported that hyperthermia has a large effect on the growth of planktonic and biofilm-producing strains. Therefore, we propose a new strategy based on AgNPs functionalized with amikacin and combined with hyperthermia (41°C to 42°C) to treat AMR and biofilm-related infections.This study was supported by research grants from the Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III (FIS 01162); la Marató TV3 (472/U/2018); the CaixaImpulse Program (Fundació LaCaixa); and the Spanish Network for Research in Infectious Diseases (REIPI RD19/0016)

    Microbial fuel cells: a green and alternative source for bioenergy production

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    Microbial fuel cell (MFC) represents one of the green technologies for the production of bioenergy. MFCs using microalgae produce bioenergy by converting solar energy into electrical energy as a function of metabolic and anabolic pathways of the cells. In the MFCs with bacteria, bioenergy is generated as a result of the organic substrate oxidation. MFCs have received high attention from researchers in the last years due to the simplicity of the process, the absence in toxic by-products, and low requirements for the algae growth. Many studies have been conducted on MFC and investigated the factors affecting the MFC performance. In the current chapter, the performance of MFC in producing bioenergy as well as the factors which influence the efficacy of MFCs is discussed. It appears that the main factors affecting MFC’s performance include bacterial and algae species, pH, temperature, salinity, substrate, mechanism of electron transfer in an anodic chamber, electrodes materials, surface area, and electron acceptor in a cathodic chamber. These factors are becoming more influential and might lead to overproduction of bioenergy when they are optimized using response surface methodology (RSM)

    Efectos del entrenamiento en conciencia fonológica y velocidad de denominación sobre la lectura. Un estudio longitudinal

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    Existen una serie de predictores que contribuyen directamente a la precisión y a la velocidad lectora. En este trabajo se analizan los efectos que un programa de instrucción en dos de dichos predictores, “conciencia fonológica” y “velocidad de denominación”, tienen sobre el aprendizaje de la lectura. Los participantes fueron 326 escolares (171 del grupo experimental y 155 del grupo control) que cursaban 2º y 3º de educación infantil y primero de primaria al comenzar la instrucción. Procedían de cuatro colegios (dos públicos y dos concertados). El grupo experimental recibió entrenamiento explícito en conciencia fonológica y velocidad de denominación durante tres cursos, dos días a la semana. El grupo control siguió el plan curricular ofi cial. El grupo experimental obtuvo puntuaciones signifi cativamente más altas que el grupo control en las pruebas de conciencia fonológica y denominación rápida, y obtuvo mejores puntuaciones en tareas de lectura en los tres primeros cursos de primaria. Los resultados indican que la intervención explícita mejora la precisión y velocidad en la lectura de palabras y de pseudopalabras y orientan la intervención en el aula.Reading predictors directly contribute to reading accuracy and speed. This study analyses the effect of an instructional programme aimed at improving two of these reading predictors, phonological awareness and naming speed. Participants were 326 children (171 in the experimental group and 155 in the control group) in grades second and third year preschool and fi rst year primary school at the onset. They attended four schools (2 public and 2 private). The experimental group was explicitly trained in phonological awareness and naming speed during three consecutive years two days a week. The control group followed the offi cial curriculum. Results show that this explicit intervention improves words and pseudowords reading accuracy and speed and provides keys for future intervention
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