ALBERT

Description: Chitosan/bacterial cellulose composite films containing diamond nanoparticles (NDs) with potential application as wound dressing are introduced. Microstructural studies show that NDs are uniformly dispersed in the matrix, although slight agglomeration at concentrations above 2 wt % is seen. Fourier transform infrared spectroscopy reveals formation of hydrogen bonds between NDs and the polymer matrix. X-ray diffraction analysis indicates reduced crystallinity of the polymer matrix in the presence of NDs. Approximately 3.5-fold increase in the elastic modulus of the composite film is obtained by the addition of 2 wt % NDs. The results of colorimetric analysis show that the composite films are transparent but turn to gray-like and semitransparent at high ND concentrations. Additionally, a decrease in highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gap is also seen, which results in a red shift and higher absorption intensity towards the visible region. Mitochondrial activity assay using L929 fibroblast cells shows that the nanocomposite films are biocompatible (>90%) after 24 h incubation. Multiple lamellapodia and cell-cell interaction are shown. The results suggest that the developed films can potentially be used as a flexible platform for wound dressing.

Description: In the context of the liberalization of electricity markets, forecasting prices is essential. With this aim, research has evolved to model the particularities of electricity prices. In particular, dynamic factor models have been quite successful in the task, both in the short and long run. However, specifying a single model for the unobserved factors is difficult, and it cannot be guaranteed that such a model exists. In this paper, model averaging is employed to overcome this difficulty, with the expectation that electricity prices would be better forecast by a combination of models for the factors than by a single model. Although our procedure is applicable in other markets, it is illustrated with an application to forecasting spot prices of the Iberian Market, MIBEL (The Iberian Electricity Market). Three combinations of forecasts are successful in providing improved results for alternative forecasting horizons.

Description: Wireless sensor networks deployed within metallic cavities are known to suffer from a very severe fading, even in strong line-of-sight propagation conditions. This behavior is well-captured by the Two-Wave with Diffuse Power (TWDP) fading distribution, which shows great fit to field measurements in such scenarios. In this paper, we address the joint estimation of the parameters K and Δ that characterize the TWDP fading model, based on the observation of the received signal envelope. We use a moment-based approach to derive closed-form expressions for the estimators of K and Δ, as well as closed-form expressions for their asymptotic variance. Results show that the estimation error is close to the Cramer-Rao lower bound for a wide range of values of the parameters K and Δ. The performance degradation due to a finite number of observations is also analyzed.

Description: Delay tracking of spread-spectrum signals is widely used for ranging in radio frequency based navigation. Its use in non-coherent optical ranging, however, has not been extensively studied since optical channels are less subject to narrowband interference situations where these techniques become more useful. In this work, an early-late delay-locked loop adapted to indoor optical ranging is presented and analyzed. The specific constraints of free-space infrared channels in this context substantially differ from those typically considered in radio frequency applications. The tracking stage is part of an infrared differential range measuring system with application to mobile target indoor localization. Spread-spectrum signals are used in this context to provide accurate ranging while reducing the effect of multipath interferences. The performance of the stage regarding noise and dynamic errors is analyzed and validated, providing expressions that allow an adequate selection of the design parameters depending on the expected input signal characteristics. The behavior of the stage in a general multipath scenario is also addressed to estimate the multipath error bounds. The results, evaluated under realistic conditions corresponding to an 870 nm link with 25 MHz chip-rate, built with low-cost up-to-date devices, show that an overall error below 6% of a chip time can be achieved.

Description: Over the past few years, Intelligent Spaces (ISs) have received the attention of many Wireless Sensor Network researchers. Recently, several studies have been devoted to identify their common capacities and to set up ISs over these networks. However, little attention has been paid to integrating Fuzzy Rule-Based Systems into collaborative Wireless Sensor Networks for the purpose of implementing ISs. This work presents a distributed architecture proposal for collaborative Fuzzy Rule-Based Systems embedded in Wireless Sensor Networks, which has been designed to optimize the implementation of ISs. This architecture includes the following: (a) an optimized design for the inference engine; (b) a visual interface; (c) a module to reduce the redundancy and complexity of the knowledge bases; (d) a module to evaluate the accuracy of the new knowledge base; (e) a module to adapt the format of the rules to the structure used by the inference engine; and (f) a communications protocol. As a real-world application of this architecture and the proposed methodologies, we show an application to the problem of modeling two plagues of the olive tree: prays (olive moth, Prays oleae Bern.) and repilo (caused by the fungus Spilocaea oleagina). The results show that the architecture presented in this paper significantly decreases the consumption of resources (memory, CPU and battery) without a substantial decrease in the accuracy of the inferred values.

Description: Background: Schools are important settings for the promotion of a healthy diet and sufficient physical activity and thus overweight prevention. Objective: To assess differences in school nutrition environment and body mass index (BMI) in primary schools between and within 12 European countries. Methods: Data from the World Health Organization (WHO) European Childhood Obesity Surveillance Initiative (COSI) were used (1831 and 2045 schools in 2007/2008 and 2009/2010, respectively). School personnel provided information on 18 school environmental characteristics on nutrition and physical activity. A school nutrition environment score was calculated using five nutrition-related characteristics whereby higher scores correspond to higher support for a healthy school nutrition environment. Trained field workers measured children’s weight and height; BMI-for-age (BMI/A) Z-scores were computed using the 2007 WHO growth reference and, for each school, the mean of the children’s BMI/A Z-scores was calculated. Results: Large between-country differences were found in the availability of food items on the premises (e.g., fresh fruit could be obtained in 12%-95% of schools) and school nutrition environment scores (range: 0.30-0.93). Low-score countries (Bulgaria, Czech Republic, Greece, Hungary, Latvia and Lithuania) graded less than three characteristics as supportive. High-score (≥0.70) countries were Ireland, Malta, Norway, Portugal, Slovenia and Sweden. The combined absence of cold drinks containing sugar, sweet snacks and salted snacks were more observed in high-score countries than in low-score countries. Largest within-country school nutrition environment scores were found in Bulgaria, Czech Republic, Greece, Hungary, Latvia and Lithuania. All country-level BMI/A Z-scores were positive (range: 0.20-1.02), indicating higher BMI values than the 2007 WHO growth reference. With the exception of Norway and Sweden, a country-specific association between the school nutrition environment score and the school BMI/A Z-score was not observed. Conclusions: Some European countries have implemented more school policies that are supportive to a healthy nutrition environment than others. However, most countries with low school nutrition environment scores also host schools with supportive school environment policies, suggesting that a uniform school policy to tackle the “unhealthy” school nutrition environment has not been implemented at the same level throughout a country and may underline the need for harmonized school policies.

Description: Atmospheric transport and in situ oxidation are important factors influencing mercury concentrations at the surface and wet and dry deposition rates. Contributions of both natural and anthropogenic processes can significantly impact burdens of mercury on local, regional and global scales. To address these key issues in atmospheric mercury research, airborne measurements of mercury speciation and ancillary parameters were conducted over a region near Tullahoma, Tennessee, USA, from August 2012 to June 2013. Here, for the first time, we present vertical profiles of Hg speciation from aircraft for an annual cycle over the same location. These airborne measurements included gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate bound mercury (PBM), as well as ozone (O3), sulfur dioxide (SO2), condensation nuclei (CN) and meteorological parameters. The flights, each lasting ~3 h, were conducted typically one week out of each month to characterize seasonality in mercury concentrations. Data obtained from 0 to 6 km altitudes show that GEM exhibited a relatively constant vertical profile for all seasons with an average concentration of 1.38 ± 0.17 ng∙m−3. A pronounced seasonality of GOM was observed, with the highest GOM concentrations up to 120 pg∙m−3 in the summer flights and lowest (0–20 pg∙m−3) in the winter flights. Vertical profiles of GOM show the maximum levels at altitudes between 2 and 4 km. Limited PBM measurements exhibit similar levels to GOM at all altitudes. HYSPLIT back trajectories showed that the trajectories for elevated GOM (>70 pg∙m−3) or PBM concentrations (>30 pg∙m−3) were largely associated with air masses coming from west/northwest, while events with low GOM (〈20 pg∙m−3) or PBM concentrations (〈5 pg∙m−3) were generally associated with winds from a wider range of wind directions. This is the first set of speciated mercury vertical profiles collected in a single location over the course of a year. Even though there are current concerns that the KCl denuders used in this study may under-collect GOM, especially in the presence of elevated ozone, the collected data in this region shows the strong seasonality of oxidized mercury concentrations throughout the low to middle free troposphere.

Description: Materials, Vol. 11, Pages 1612: Transmission Attenuation Power Ratio Analysis of Flexible Electromagnetic Absorber Sheets Combined with a Metal Layer Materials doi: 10.3390/ma11091612 Authors: Jorge Victoria Adrian Suarez Jose Torres Pedro A. Martinez Antonio Alcarria Julio Martos Raimundo Garcia-Olcina Jesus Soret Steffen Muetsch Alexander Gerfer Electromagnetic noise absorber sheets have become a solution for solving complex electromagnetic interference (EMI) problems due to their high magnetic losses. This contribution is focused on characterizing a novel structure that is based on an absorber film with a metal layer attached on its top side. Two different absorber compositions were combined with Al and Cu metal layers in order to study the improvement on the performance of these structures, depending on the complex permeability, absorber film thickness, and type of metal. The transmission attenuation power ratio of the absorber films is analyzed and compared to the performance of absorber and metal structures. The measurement procedure is carried out attaching the films into a microstrip line that has been designed based on IEC standard (IEC 62333-2). This test fixture is employed as a transmission line to simulate a general noise path. The performance of absorber composites to filter electromagnetic noise is evaluated through analyzing S21 and S11 parameters. This is carried out with the aim of finding out in which conditions the absorption loss is improved when a metal layer is attached. In addition, the possible re-radiation effect, due to the magnetic field that is generated by the eddy currents induced in the metal layer, is examined.

Description: Entropy, Vol. 20, Pages 698: Combining Entropy Measures for Anomaly Detection Entropy doi: 10.3390/e20090698 Authors: Alberto Muñoz Nicolás Hernández Javier M. Moguerza Gabriel Martos The combination of different sources of information is a problem that arises in several situations, for instance, when data are analysed using different similarity measures. Often, each source of information is given as a similarity, distance, or a kernel matrix. In this paper, we propose a new class of methods which consists of producing, for anomaly detection purposes, a single Mercer kernel (that acts as a similarity measure) from a set of local entropy kernels and, at the same time, avoids the task of model selection. This kernel is used to build an embedding of data in a variety that will allow the use of a (modified) one-class Support Vector Machine to detect outliers. We study several information combination schemes and their limiting behaviour when the data sample size increases within an Information Geometry context. In particular, we study the variety of the given positive definite kernel matrices to obtain the desired kernel combination as belonging to that variety. The proposed methodology has been evaluated on several real and artificial problems.

Description: Water, Vol. 9, Pages 600: How Efficient Are Semi-Natural Ponds in Assimilating Wastewater Effluents? Application to Fuente de Piedra Ramsar, Mediterranean Salt Lake (South of Spain) Water doi: 10.3390/w9080600 Authors: Jesús de-los-Ríos-Mérida Andreas Reul María Muñoz Salvador Arijo Silvana Tapia-Paniagua Manuel Rendón-Martos Francisco Guerrero This work concerns the case study of a Mediterranean Ramsar salt lake (Fuente de Piedra, southern Spain) that receives the treated wastewater of the local village treatment plant. The wastewater goes through a system of canals, water dams, and three semi-natural ponds that were built in 2005. This work aims to investigate the capacity of the system to assimilate the impact of wastewater effluents on Lake Fuente de Piedra. For this, four points were sampled on 27–29 April 2016, at the inlet and the outlet points of the first and the third semi-natural ponds, with three replicates each. Temperature, pH, and conductivity at the inlet were 19.62 °C, 7.99, and 3262.67 μS/cm, respectively, and increased through the pond system by 7.59%, 8.04%, and 37.34%, respectively. Phytoplankton concentration indicators decreased from the inlet point to the outlet point (chlorophyll a from >500 to <20mg/L), as did the biovolume (from >5 × 1010 to 4.3 × 109 μm3/mL). Zooplankton biovolume, in contrast, increased three orders of magnitude from the inlet (3.5 × 107 μm3/mL) to the outlet point (1.6 × 109 μm3/mL). Heterotrophic bacteria (1.29 × 105 cfu/mL) and faecal enterococci (1033 ± 351 cfu/100 mL) were high at the inlet point, but decreased at the outlet point by almost three orders of magnitude. Total phosphorous and total nitrogen decreased 40.3% and 23.1% through the pond system. The results showed an improvement in water quality in its passage through the built system. Additionally, as permanent wetlands with acceptable water quality, the water system attracts wild fauna during the dry summer, leading to the conclusion that these semi-natural or artificial wetlands should be extrapolated to other aquatic ecosystems (Mediterranean wetlands) that receive contributions of residual waters. Better functioning of the treatment plant is desirable to improve the conservation of the Ramsar and adjacent wetlands systems.