Solar Cell Parameter Extraction Method from Illumination and Dark I-V Characteristics.

A novel method to extract the seven parameters of the double-diode model of solar cells using the current-voltage (I-V) characteristics under illumination and in the dark is presented. The algorithm consists of two subroutines which are alternatively run to adjust all the parameters of the cell in an iterative process. Curve fitting of the light I-V characteristics ensures accuracy in the prediction of the maximum power point, whereas simultaneously fitting the dark I-V characteristics results in a set of physically meaningful parameters that provide information about the physical performance of the photovoltaic devices. Experimental I-V curves of in-house solar cells are used to validate the proposed parameter extraction method, which can be furthermore applied to other types of p-n junction-based photovoltaic devices.

High-Level Modeling and Simulation Tool for Sensor Conditioning Circuit Based on Artificial Neural Networks.

For current microelectronic integrated systems, the design methodology involves different steps that end up in the full system simulation by means of electrical and physical models prior to its manufacture. However, the higher the circuit complexity, the more time is required to complete these simulations, jeopardizing the convergence of the numerical methods and, hence, meaning that the reliability of the results are not guaranteed. This paper shows the use of a high-level tool based on Matlab to simulate the operation of an artificial neural network implemented in a mixed analog-digital CMOS process, intended for sensor calibration purposes. The proposed standard tool enables modification of the neural model architecture to adapt its characteristics to those of the electronic system, resulting in accurate behavioral models that predict the complete microelectronic IC system behavior under different operation conditions before its physical implementation with a simple, time-efficient, and reliable solution.

Low-Power Highly Robust Resistance-to-Period Converter.

This paper presents a novel structure of Resistance- to-Period (R-T) Converter highly robust to supply and temperature variations. Robustness is achieved by using the ratiometric approach so that complex circuits or high accuracy voltage references are not necessary. To prove the proposed architecture of R-T converter, a prototype was implemented in a 0.18 µ m CMOS process with a single supply voltage of 1.8 V and without any stable reference voltage. Experimental results show a maximum ±1.5% output signal variation for ±10% supply voltage variation and in a 3⁻95 ° C temperature range.

An integrated low-power lock-in amplifier and its application to gas detection.

This paper presents a new micropower analog lock-in amplifier (LIA) suitable for battery-operated applications thanks to its reduced size and power consumption as well as its operation with single-supply voltage. The proposed LIA was designed in a 0.18 µm CMOS process with a single supply voltage of 1.8 V. Experimental results show a variable DC gain ranging from 24.7 to 42 dB, power consumption of 417 µW and integration area of 0.013 mm2. The LIA performance was demonstrated by measuring carbon monoxide concentrations as low as 1 ppm in dry N2. The experimental results show that the response to CO of the sensing system can be considerably improved by means of the proposed LIA.

Renal function and short-term outcome in stable outpatients with coronary, cerebrovascular or peripheral artery disease.

BACKGROUND: The influence of renal function on outcome in stable outpatients with atherosclerotic disease has not been thoroughly studied. METHODS: We used the FRENA Registry data to compare the incidence of subsequent ischemic events (myocardial infarction [MI], ischemic stroke or limb amputation) in patients with coronary (CAD), cerebrovascular (CVD) or peripheral artery disease (PAD), according to their estimated glomerular filtration rate (eGFR) at baseline. RESULTS: As of April 2012, 3860 patients were recruited in FRENA: 1439 with CAD, 1118 with CVD and 1303 with PAD. Over a mean follow-up of 14 ± 12 months, 97 patients suffered subsequent MI, 93 had ischemic stroke and 46 underwent limb amputation. In all, 2699 patients (70%) had eGFR > 60 mL/min/1.73 m(2), 1022 (26%) had 30-60 mL/min/1.73 m(2), and 139 (3.6%) had <30 mL/min/1.73 m(2). Among patients with CAD, the rate of subsequent MI was: 1.38 (95% CI: 0.85-2.11), 5.79 (95% CI: 3.90-8.31) and 18.8 (95% CI: 9.14-34.4) events per 100 patient-years, respectively. On multivariable analysis, the hazard ratio for MI (compared with patients with eGFR > 60 mL/min/1.73 m(2)) was of 1.77 (95% CI: 1.15-2.73) for patients with eGFR of 30-60 mL/min/1.73 m(2), and 3.15 (95% CI: 1.61-6.14) for those with eGFR < 30 mL/min/1.73 m(2). Among patients with CVD or PAD, there was no increasing rate of subsequent ischemic events with decreasing renal function. CONCLUSIONS: Among stable outpatients with CAD, there is an increasing rate of subsequent MI with decreasing renal function, independently of potentially confounding variables. These findings were not observed in patients with CVD or PAD.

Smoking cessation and outcome in stable outpatients with coronary, cerebrovascular, or peripheral artery disease.

BACKGROUND: The influence of smoking cessation on outcome in patients with peripheral arterial disease (PAD) has not been thoroughly studied. METHODS: FRENA is an ongoing registry of stable outpatients with symptomatic coronary artery disease (CAD), cerebrovascular disease (CVD), or PAD. We compared the mortality rate of those who quit vs. those who continued smoking. RESULTS: As of December 2010, 3523 patients were recruited, of whom 1182 (34%) were current smokers. Of these, 475 patients (40%) had CAD, 240 (20%) had CVD, and 467 (40%) had PAD. In all, 512 patients (43%) quit smoking. Over a mean follow-up of 14 months, 32 patients (2.7%) died and 95 (8.0%) had subsequent ischaemic events (myocardial infarction 32, ischaemic stroke 20, critical limb ischaemia/disabling claudication 53). In patients with CAD, the mortality rate was significantly lower in recent quitters (0.77 vs. 3.73 deaths per 100 patient-years; p = 0.013) than in persistent smokers. No quitter with CVD died (0.0 vs. 2.18 deaths; p = 0.092); but in patients with PAD there was a trend towards a higher mortality in quitters than in those who continued smoking (4.29 vs. 2.27 deaths; p = 0.357). On multivariate analysis, the relative risk for death in quitters was 0.20 (95% CI 0.05-0.75) in patients with CAD, 0.0 in those with CVD, and 1.83 (95% CI 0.65-5.15) in those with PAD. CONCLUSIONS: Smoking cessation was associated with a significant decrease in mortality in patients with CAD, a non-significant decrease in those with CVD, and a non-significant increase in those with PAD.

Auditory maturity and hearing performance in inner ear malformations: a histological and electrical stimulation approach.

The objective of this study was to assess the auditory performance of the neural structures in response to controlled electrical stimulation period. A prospective cohort study focused on the intracochlear electrical stimulation parameters and hearing performance of patients suffering different cochlear malformations who were treated by cochlear implants constituted the study design. The study sample constituted 16 patients, suffering profound prelingual hearing impairment, diagnosed on the basis of radiological criteria as having an inner ear malformation, and who underwent cochlear implantation and were followed for 24 months. Patients with common cavities, characterized by fewer nerve structures involved, less epithelial penetration, and deficient cochlear tonotopy distribution showed have higher thresholds and electrical charges than patients with cochlear hypoplasia, who in turn have higher thresholds than patients with minor malformations (p < 0.05). Furthermore, word perception was severely compromised in patients with a common cavity malformation and was also poor in patients with cochlear hypoplasia, who were unable to discriminate more than 50% of the words and relied on visual cues as a necessary aid to communication. Better results were reached by minor malformed inner ears. To conclude, the number of nerve structures involved, epithelial penetration and deficient cochlear tonotopy are responsible of inner ear functionality.

Mejora del acceso a la artroplastia total de rodilla: experiencia de una unidad monográfica / Improved accessibility in total knee arthroplasty: experience of a specialized unit

Introducción: En mayo de 2004 se implantó un programa específico para la cirugía protésica de rodilla, dada la alta demanda para este tipo de cirugía. El objetivo de este trabajo es evaluar los resultados de los indicadores asistenciales y de calidad obtenidos en una unidad monográfica de prótesis de rodilla (UEPR), y compararlos con los obtenidos previamente en una unidad asistencial convencional de cirugía ortopédica y traumatología (UCOT). Material y metodo: La población objeto de este ensayo comunitario no controlado (antes-después) han sido los primeros 124 pacientes atendidos en la UEPR y los últimos 124 pacientes a quienes se había realizado este mismo tipo de intervención en la UCOT. Edad, sexo, días de estancia, dolor, deambulación al alta, flexión de la rodilla, comorbilidades y complicaciones han sido las variables analizadas. Resultados: Los pacientes atendidos en la UEPR estaban menos tiempo ingresados (p < 0,0001) y presentaban una mayor flexión de la rodilla intervenida al alta (p < 0,0001). En general la UEPR atendió a enfermos con un mayor número de comorbilidades que la UCOT. Conclusiones: El diseño y la puesta en funcionamiento de unidades monográficas y especializadas en la atención de pacientes quirúrgicos de alta prevalencia puede ser una alternativa satisfactoria en la resolución de este problema endémico de la sanidad pública. Estas unidades deben desarrollar su actividad según una guía clínica específica y evaluar la calidad asistencial conforme a una serie de indicadores y objetivos que posibiliten su mejora continua

Introduction: In May 2004 a specific program for knee prosthesis surgery was established, due to the high demand for this type of surgery. The aim of this study was to assess the outcomes of clinical and quality indicators obtained in a monographic hospitalization unit specialized in knee prosthesis surgery compared with the outcomes previously obtained in a standard orthopedic surgery hospitalization unit. Material and method: The sample of this non-controlled community trial (before-after) consisted of the first 124 patients treated in the specialized unit and the last 124 patients treated in the standard unit for the same type of surgery. Age, gender, pain, length of hospital stay in days, movement at discharge, knee bending, comorbidity and complications were analyzed. Results: Patients admitted to the specialized unit spent less time in the hospital (p < 0.0001) and showed better knee bending at discharge (p < 0.0001). In general the specialized unit attended patients with a greater number of comorbidities than the standard unit. Conclusions: Creating a monographic unit specialized in the care of surgical patients with high prevalence could be a possible solution to this chronic problem in public hospitals. These units should follow a specific clinical pathway and should assess quality according to a group of indicators and objectives that allow continuous improvement