Zero Jordan product determined Banach algebras

A Banach algebra $A$ is said to be a zero Jordan product determined Banach algebra if every continuous bilinear map $\varphi\colon A\times A\to X$, where $X$ is an arbitrary Banach space, which satisfies $\varphi(a,b)=0$ whenever $a$, $b\in A$ are such that $ab+ba=0$, is of the form $\varphi(a,b)=\sigma(ab+ba)$ for some continuous linear map $\sigma$. We show that all $C^*$-algebras and all group algebras $L^1(G)$ of amenable locally compact groups have this property, and also discuss some applications

Assessment of Aspergillus niger biofilm growth kinetics in minibioreactors by carbon dioxide evolution

Aspergillus niger ATCC 10864 was grown on bubble minicolumns aerated with pure oxygen either as biofilm or free-mycelium submerged systems. Growth kinetics was followed by estimating biomass from released carbon dioxide using a titration method and mathematical models. Submerged cultures showed increased endogenous respiration rates (0.0298 vs. 0.0004 g biomass/g biomass.h) possibly related to stress condition since this type of growth is not the natural way of life of A. niger. On the other hand, A. niger biofilm growth followed a logistic model having higher maximal specific growth rate than submerged cultures (0.061 vs. 0.045 h-1). This may be related to better mass transfer processes due to a channeled mycelial microstructure. Biofilm growth can be easily and reliable assessed by evaluating the CO2 released during the fermentation in minibioreactors.Key words: Aspergillus niger, biofilm, mathematical modeling, endogenous respiration, Cryo-SEM

¿Contribuimos a la capacitación docente con el prácticum? Análisis de la percepción del estudiantado

El PRACTICUM o prácticas externas curriculares, es una asignatura desgranada en Prácticum I y Prácticum II que forma parte del plan de estudios del máster de secundaria que realiza la UPC desde el curso 2009/10. Las dos asignaturas representan el 23% de la totalidad de créditos de la titulación y por su carácter transversal, se realiza a lo largo del curso académico. El objetivo del prácticum está muy ligado a las asignaturas presenciales ya que pretende impulsar un modelo de aprendizaje basado en la alternancia, dónde los conocimientos teórico-prácticos y las experiencias en entornos reales de trabajo convergen para garantizar la adquisición de competencias profesionales de los futuros docentes de secundaria. Dado éste contexto y el hecho de haber experimentado un proceso de acreditación de la titulación dónde se generaron muchas reflexiones que provocan crear espacios de mejora, se propone el siguiente trabajo. Se plantea un proceso de análisis y estudio para detectar áreas de mejora que impacten en toda la titulación. Aunque la valoración del estudiantado que cursa el máster, sobre el prácticum es muy positiva, no dejamos de preguntarnos qué competencias docentes se trabajan y cuáles no y en qué grado, con el objetivo de definir actividades para abordar aquellas que los alumnos no las perciben como adquiridas. Por lo tanto, el objetivo es crear un método que nos permita analizar la autoevaluación inicial i final del estudiantado en referencia a la adquisición de las competencias docentes (el máster de secundaria es una titulación con atribuciones profesionales). De ésta manera podremos constatar si se confirman nuestras hipótesis de partida, identificar que competencias tendríamos que trabajar para conseguir una óptima capacitación del futuro docente y, de forma general, reflexionar con todo el profesorado implicado sobre el resultado del estudioPeer ReviewedPostprint (author's final draft

Maps preserving zeros of a polynomial

Let \A be an algebra and let $f(x_1,...,x_d)$ be a multilinear polynomial in noncommuting indeterminates $x_i$. We consider the problem of describing linear maps \phi:\A\to \A that preserve zeros of $f$. Under certain technical restrictions we solve the problem for general polynomials $f$ in the case where \A=M_n(F). We also consider quite general algebras \A, but only for specific polynomials $f$.Comment: 11 pages, accepted for publication in Linear Algebra App

A Comparative Study of Electric Load Curve Changes in an Urban Low-Voltage Substation in Spain during the Economic Crisis (2008-2013)

This paper presents a comparative study of the electricity consumption (EC) in an urban low-voltage substation before and during the economic crisis (2008-2013). This low-voltage substation supplies electric power to near 400 users. The EC was measured for an 11-year period (2002-2012) with a sampling time of 1 minute. The study described in the paper consists of detecting the changes produced in the load curves of this substation along the time due to changes in the behaviour of consumers. The EC was compared using representative curves per time period (precrisis and crisis). These representative curves were obtained after a computational process, which was based on a search for days with similar curves to the curve of a determined (base) date. This similitude was assessed by the proximity on the calendar, day of the week, daylight time, and outdoor temperature. The last selection parameter was the error between the nearest neighbour curves and the base date curve. The obtained representative curves were linearized to determine changes in their structure (maximum and minimum consumption values, duration of the daily time slot, etc.). The results primarily indicate an increase in the EC in the night slot during the summer months in the crisis perio

Effects of ultrasound treatments on wine microorganisms

Ultrasound is one of the most promising non-thermal an emerging technique in food technology. The objective of the present work was to evaluate the effect of different ultrasonic treatments on the most important wine microbiota (Saccharomyces and non-Saccharomyces yeasts and lactic acid bacteria). Two stages were carried out: the assessment step, where six different ultrasonic treatments (with varying power, time, and pulses) were used on Saccharomyces cerevisiae, Brettanomyces spp., and Lactiplantibacillus plantarum; and the validation step, where two chosen ultrasonic treatments were used on Zigosaccharomyces bailli, Brettanomyces spp., Saccharomyces cerevisiae, Saccharomyces bayanus, Pichia membranifaciens, Schizosaccharomyces pombe, and Hanseniaspora osmophila. The most sensitive microorganism was Brettanomyces spp., and the most resistant was Lactiplantibacillus plantarum. Ultrasonic treatments had varying effects on vitality (delay of growth or maximum OD reduction) and on viability (reduction of microbial growth)