Synthesis of c-axis oriented AlN thin films on different substrates: A review

Highly c-axis oriented AlN thin films have been deposited by reactive sputtering on different substrates. The crystallographic properties of layered film structures consisting of a piezoelectric layer, aluminum nitride (AlN), synthesized on a variety of substrates, have been examined. Aluminum nitride thin films have been deposited by reactive pulsed-DC magnetron sputtering using an aluminum target in an Ar/N₂ gas mixture. The influence of the most critical deposition parameters on the AlN thin film crystallography has been investigated by means of X-ray diffraction (XRD) analysis of the rocking curve Full-Width at Half Maximum (FWHM) of the AlN-(0 0 0 2) peak. The relationship between the substrate, the synthesis parameters and the crystallographic orientation of the AlN thin films is discussed. A guide is provided showing how to optimize these conditions to obtain highly c-axis oriented AlN thin films on substrates of different nature.     

Participation of women in doctorate,research, innovation,and management activities at Universidad Politécnica de Madrid: analysis of the decade 2006–2016

Scientometrics - This article studies the participation of women in doctorate, lecturing and research, innovation, and management activities at Universidad Politécnica de Madrid (UPM), the...     

Post-harvest physiological deterioration in several cassava genotypes over sequential harvests and effect of pruning prior to harvest

Consumers, traders and processors consider post-harvest physiological deterioration (PPD) an important constraint. In Experiment 1, PPD was assessed three consecutive years in roots from five genotypes through seven storage days. PPD, scopoletin and dry matter content (DMC) was recorded during storage. Year, genotype, duration of storage and their interactions were significant. PPD was associated with duration of storage period, DMC and scopoletin contents. Ambient moisture and temperature during storage influenced PPD. In Experiment 2, roots from seven clones were harvested 10 months after planting from 30 consecutive biweekly plantings. PPD was assessed 0, 2 and 7 days after harvest. In 13 harvests, roots from plants pruned six days earlier were also evaluated. Results indicated large seasonal variation across genotypes. Pruning reduced PPD and DMC. Complex and contrasting relationships among the variables analysed were found. There is no uniform model explaining the relationship between PPD and the independent variables considered.     

Statistical user model supported by R-Tree structure

This paper is about developing a group user model able to predict unknown features (attributes, preferences, or behaviors) of any interlocutor. Specifically, for systems where there are features that cannot be modeled by a domain expert within the human computer interaction. In such cases, statistical models are applied instead of stereotype user models. The time consumption of these models is high, and when a requisite of bounded response time is added most common solution involves summarizing knowledge. Summarization involves deleting knowledge from the knowledge base and probably losing accuracy in the medium-term. This proposal provides all the advantages of statistical user models and avoids knowledge loss by using an R-Tree structure and various search spaces (universes of users) of diverse granularity for solving inferences with enhanced success rates. Along with the formalization and evaluation of the approach, main advantages will be discussed, and a perspective for its future evolution is provided. In addition, this paper provides a framework to evaluate statistical user models and to enable performance comparison among different statistical user models.     

High‐efficiency black silicon interdigitated back contacted solar cells on p‐type and n‐type c‐Si substrates

This work demonstrates the high potential of Al₂O₃ passivated black silicon in high‐efficiency interdigitated back contacted (IBC) solar cells by reducing surface reflectance without jeopardizing surface passivation. Very low reflectance values, below 0.7% in the 300–1000 nm wavelength range, together with striking surface recombination velocities values of 17 and 5 cm/s on p‐type and n‐type crystalline silicon substrates, respectively, are reached. The simultaneous fulfillment of requirements, low reflectance and low surface recombination, paves the way for the fabrication of high‐efficiency IBC Si solar cells using black silicon at their front surface. Outstanding photovoltaic efficiencies over 22% have been achieved both in p‐type and n‐type 9‐cm² cells. 3D simulations suggest that efficiencies of up to 24% can be obtained in the future with minor modifications in the baseline fabrication process. Copyright © 2015 John Wiley & Sons, Ltd.     

Semicarbazide in baby food: a European survey

The concentration of semicarbazide (SEM) in baby food packed in glass jars with lids sealed with plastic gaskets was determined in more than 100 samples, produced in 11 European countries, and purchased at local supermarkets in 14 countries. The method used for the analyses has been recently validated in a collaborative study. A correlation between the measured SEM concentration and the type of food (fruit, vegetables, meat and combinations of those) was found. The lowest values of SEM were found in samples containing only fruit with a mean concentration of 5.5±3.8 μg/kg. Some brands were characterised by low levels of SEM regardless of the composition. The levels of SEM found were comparable for the different countries of production. Both, high and low semicarbazide levels were found among organic and conventional samples.     

Preoperative coronarography in heart valve disease patients. A probability analysis of coronary lesion

INTRODUCTION AND OBJECTIVES: The indication of preoperative coronary angiography is routinely performed for patients who are going to valve replacement surgery. The need of coronary angiography is based on age, gender and previous angina, but it is not usually based on risk factors. The purpose of this study has been to find markers to predict the probability of coronary lesion in this group of patients. PATIENTS AND METHODS: We studied retrospectively a population of 541 patients with valvular heart disease who underwent preoperative coronary angiography from 1989 to 1994. Mean age was 61.8 (range 34-82). There were 301 men and 240 women. We analyzed in each patient different variables such as age, gender, previous angina, hypertension, diabetes mellitus, tobacco and familial predisposition. We correlated these variables with the presence of coronary lesion by multivariate analysis. RESULTS: There were 73 patients with coronary lesion greater than 50%. The prevalence of significant coronary artery disease was 13.4%. Angina was present in 34.6%. The risk of coronary lesion was defined as odds ratio: previous angina 3.3; tobacco 2.6; diabetes 2.2; hypertension 1.8 and age 1.4. The others variables were not predictor of coronary lesion. The probability of coronary lesion in patients without those variables (angina, tobacco, diabetes, hypertension) was 4%. If we analyzed age, the probability of coronary lesion was 3% in patients under 65 years and 6% above 65 years. CONCLUSIONS: The lack of previous angina and at least the three risk factors described as predictors of coronary lesion (hypertension, tobacco and diabetes) can define a group of patients with a very low prevalence of coronary lesion, especially if they are under 65 years. It can allow us to avoid preoperatory coronary angiography in patients who undergo valve replacement.     

NEURAL NETWORKS AND HAUSDORFF DISTANCE APPLIED TO NUMBER RECOGNITION IN ELECTRICAL METERS

Pattern recognition is the area of research dedicated to recognizing objects, images, faces, letters, numbers, and so forth. Number recognition processes have an important role in remotely monitoring data for electrical meter readings, and monitoring data from these devices can help to reduce energy consumption. Research in the area of number recognition is vast and there are many different methods have been developed; some of these approaches follow characteristics extraction methods and others, such as the Hausdorff Distance, use the calculation of the distance between two finite sets. In this article, some of these approaches and a comparison among them are presented. Results showed that for recognizing complete digits, characteristic extraction methods offer a better result in terms of recognition time than Hausdorff Distance methods; however, both are similar when considering recognition percentage.     

Using AHS hyper-spectral images to study forest vegetation recovery after a fire

Recent advances in sensor technology have led to the development of new hyper-spectral instruments capable of measuring reflected radiation over a wide range of wavelengths. These instruments can be used to assess the diverse characteristics of vegetation recovery that are only noticeable in certain parts of the electromagnetic spectrum. In this research, such instruments were used to study vegetation recovery following a forest fire in a Mediterranean ecosystem. The specific event occurred in an area called El Rodenal of Guadalajara (in Central Spain) between 16 and 21 July 2005. Remotely sensed hyper-spectral multitemporal data were used to assess the forest vegetation response following the fire. These data were also combined with remotely sensed fire severity data and satellite high temporal resolution data. Four Airborne Hyperspectral Scanner (AHS) hyper-spectral images, 361 Moderate Resolution Imaging Spectroradiometer (MODIS) images, field data, and ancillary information were used in the analysis. The total burned area was estimated to be 129.4 km². AHS-derived fire severity level-of-damage assessments were estimated using the normalized burn ratio (NBR). Post-fire vegetation recovery was assessed according to a spectral unmixing analysis of the AHS hyper-spectral images and the normalized difference vegetation index (NDVI), as calculated from the MODIS time series. Combining AHS hyper-spectral images with field data provides reliable estimates of burned areas and fire severity levels-of-damage. This combination can also be used to monitor post-fire vegetation recovery trends. MODIS time series were used to determine the types and rates of vegetation recovery after the fire and to support the AHS-based estimates. Data and maps derived using this method may be useful for locating priority intervention areas and planning forest restoration projects.