Current distribution and recent development of sessile oak forests in Montseny (1956–2015)

There is a distribution limit of sessile oak (Quercus petraea) in the northern half of the Iberian Peninsula, with its southernmost populations located at the xeric limit for the species. We present here the current distribution of these populations in the Montseny Massif (N.E. Catalonia) and how the surface area they cover has developed over the last 50 years. Using a new high-resolution map (1:5000) we have calculated that Q. petraea currently covers 64.1 ha, and is found between 450 and 1150 m above sea level with a predominantly southern exposure, with the north-facing slopes being dominated by beech forests. With regard to its recent development, 44% of what is now dense forest was, in 1956, much more dispersed while 11% of it consisted of open spaces or shrubs. Such changes clearly show that, in Montseny, Q. petraea is well capable of regenerating its forest canopy as well as colonising adjacent environments.     

A Fittingness Factor-Based Spectrum Management Framework for Cognitive Radio Networks

In order to increase cognitive radios (CRs) operation efficiency, there has been an increasing interest in strengthening awareness level about spectrum utilisation. In this respect, this paper proposes to exploit the fittingness factor concept to capture the suitability of spectral resources exhibiting time-varying characteristics to support a set of heterogeneous CR applications. First, a new knowledge management functional architecture for optimizing spectrum management has been constructed. It integrates a set of advanced statistics capturing the influence of the dynamic radio environment on the fittingness factor. Then, a knowledge manager (KM) exploiting these statistics to monitor time-varying suitability of spectrum resources has been proposed to support the spectrum selection (SS) decision-making process. In particular, a new Fittingness Factor-based strategy combining two SS and spectrum mobility (SM) functionalities has been proposed, following either a greedy or a proactive approach. Results have shown that, with a proper fittingness factor function, the greedy approach efficiently exploits the KM support at low loads and the SM functionality at high loads to introduce significant gains in terms of the user dissatisfaction probability. The proactive approach has been shown to maintain the introduced performance gain while minimizing the signalling requirements in terms of spectrum handover rate.     

Effluent content from albedo degradation and kinetics at different temperatures in the enzymatic peeling of grapefruits

This work studies the variation in the effluent content from the reactor in enzymatic peeling of grapefruits, to determine the loss of soluble solids, reducing sugars and galacturonic acid, the main component from the albedo of the skin to model the solid–liquid transfer in this process. Experiments to study the efficiency of the enzymatic reaction include the effect of the temperature on the kinetics of albedo degradation to find an equation relating both variables and also the activation energy of this process, its value being 36.9 kJ/mol.     

Characterization by culture-dependent and culture-independent methods of the bacterial population of suckling-lamb packaged in different atmospheres

This study offers insight into the dynamics of bacterial populations in fresh cuts of suckling lamb under four different atmospheric conditions: air (A), and three Modified Atmosphere Packaging (MAP) environments, 15%O₂/30%CO₂/55%N₂ (C, commercial), 70%O₂/30%CO₂ (O), and 15%O₂/85%CO₂ (H) for 18 days. Microbial analyses by both conventional methods and PCR-DGGE were performed. Controversial and surprising results emerged from comparing both methods in relation to the genus Pseudomonas. Thus, conventional methods detected the presence of high numbers of Pseudomonas colonies, although PCR-DGGE only detected this genus in air-packaged samples. PCR-DGGE detected higher microbial diversity in the control samples (A) than in the modified atmospheres (C, O, H), having atmosphere H the fewest number of species. Brochothrix thermosphacta, LAB (Carnobacterium divergens and Lactobacillus sakei), and Escherichia spp. were detected in all the atmospheres throughout storage. Moreover, previously undescribed bacteria from lamb meat such as Enterobacter hormaechei, Staphylococcus equorum and Jeotgalicoccus spp. were also isolated in this study by DGGE. Additionally, qPCR analysis was used to detect and characterize strains of Escherichia coli. Virulence genes (stx₁, stx₂ and eae) were detected throughout storage in 97% of the samples. A high CO₂ atmosphere was the most effective packaging combination doubling storage time in comparison with commercial atmosphere.     

Diffusion Coefficient Measurements Under Reduced Gravity Conditions by Means of the Shear Cell Technique. The Impact of Free Surfaces

A recent computational methodology is applied here in order to analyze the impact of free surfaces on the measurement of the interdiffusion coefficients if shear cells are used. Calculations indicate that the above-mentioned impact depends on the intensity of the solutal Marangoni convection but mainly on the number of active Marangoni segments, that is to say, on the extent of the free surface considered. Bulk solutal convection due to reduced gravity levels is not relevant if the gravity vector acts orthogonally to the gradient of concentration.     

Effect of raspberry pomace extracts isolated by high pressure extraction on the quality and shelf‐life of beef burgers

Raspberry pomace extracts isolated with supercritical carbon dioxide (SCE) and pressurised ethanol/water (ETE) were tested in beef burgers. Only ETE additives effectively inhibited lipid oxidation and the growth of microorganisms, as it was observed by measuring the changes of thiobarbituric acid reactive substances, bacterial counts and the content of O₂ and CO₂ during storage in the modified atmosphere package. ETE additives also demonstrated some meat colour preservation effects, which were assessed by the intensity of hamburger colour and metmyoglobin concentration. However, ETE additives did not alter burger's taste at the applied concentrations (up to 1%). It may be concluded that the most effective extracts possessing strong antioxidant and antimicrobial activity may be isolated from raspberry pomace by the pressurised liquid extraction with a hydroethanolic solvent; such extracts may be considered as promising additives in meat products for improving their stability and enriching with beneficial to health phytochemicals.     

Explicit model for the gate tunneling current in double-gate MOSFETs

In this paper, we present an explicit compact quantum model for the gate tunneling current in double-gate metal–oxide–semiconductor field-effect transistors (DG-MOSFETs). Specifically, an explicit closed-form expression is proposed, useful for the fast evaluation of the gate leakage in the context of electrical circuit simulators. A benchmarking test against 1D self-consistent numerical solution of Schrödinger–Poisson (SP) equations has been performed to demonstrate the accuracy of the model.     

Low-intensity optical bistability in an active Fabry-Perot mirror induced by input-phase-insensitive parametric downconversion

A Fabry-Perot resonator filled with second-order nonlinear optical material is investigated. Attention is devoted to making the resonator act as a nonlinear mirror for ultralow-intensity light signals that can be switched by a control beam at the second-harmonic frequency. The interaction process is an input-phase-independent parametric downconversion. The theoretical problem is solved through implementation of a dummy variable method optimized for a parametric process. Efficient amplification and bistability of low-intensity signals have been found.     

Forthcoming Contributions

Table of Contents

Forthcoming Contributions