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Background. Fresh pasta filata cheese is considered as one of the most important foods in the Venezuelan diet. It is typically produced by small-scale producers using raw milk. The objective of this research was to molecularly characterize the pathogenic potential of Escherichia coli strains isolated from pasta filata cheese manufactured and marketed in Venezuela. Methodology. In the period between January and March of 2019, a total of 36 strains of E. coli were isolated from a variety of pasta filata cheeses including 17 samples of mozzarella, 16 of telita, and 3 of guayanés. These strains were isolated according to the Venezuelan Commission of Industrial Standards (COVENIN) and identified by conventional methods (biochemical and phenotypic tests). Antimicrobial susceptibility was determined using the disk diffusion technique. Phylogenetic grouping and detection of virulence genes were performed by Polymerase Chain Reaction amplification. Diversity and genetic relationships were determined by Rep-PCR. Results: All strains were susceptible to the tested antibiotics. Phylogroup A (n=19) was the most frequent (52.8%), followed by groups D (n=11; 30.6%), and B1 (n=2; 5.6%). The majority of isolates carried at least two virulence genes, one coding for adhesion mechanisms (fimH) and the other for iron uptake (fyuA). Only one strain of phylogroup A presented a profile consisting of four virulence genes (fimH, fyuA, kpsMT II, and papAH). Four strains that could not be classified according to Clermont's scheme carried resistance genes as well. A heterogeneous population structure was observed by Rep-PCR of the strains. Conclusion: Results support the hypothesis that the E. coli strains isolated from the three types of pasta filata cheeses manufactured and marketed in Venezuela have identical characteristics and virulence factors to Extraintestinal Pathogenic E. coli strains observed in animals and humans, posing a potential health risk. Therefore, it is essential to improve hygienic and sanitary controls at all stages of cheese production and to implement measures for epidemiological surveillance of potentially pathogenic bacterial strains present in Venezuelan, artisanal pasta filata cheeses. DOI: 10.18502/jfqhc.11.3.16589

An experimental demonstration for generating harmonics in the optical Vernier effect (OVE) by cascading tapered single-mode fibres (SMF28) is presented. The tapered optical fibres conformed to a pair of in-series Mach-Zehnder fibre interferometers (MZFI), in which one MZFI was a reference while the other was a sensor. The first-order harmonic was achieved by increasing the distance between tapers of the sensor MZFI by a multiple of (i + 1) times the distance between tapers of the reference MZFI plus a mismatch factor. A series of experiments using an individual MZFI and two MZFIs with traditional and harmonic OVE as displacement sensors were performed to compare their sensitivities and magnification factors and demonstrate the improving the sensitivity. The displacement sensor with the first-order harmonic exhibited a maximum sensitivity of −33.3 nm/mm with an M-factor of 8.53 in the mm range.

En este trabajo se hace un análisis de las diferentes fallas que se pueden presentar en los instrumentos de un proceso químico (válvula y transmisor). El método propuesto detecta y diagnostica el instrumento con problemas en el proceso. Un modelo de un proceso químico es usado para ver cómo trabaja el método propuesto, para diferenciar una falla de válvula de una falla de transmisor, se utiliza un análisis en el dominio wavelet; luego se mide la diferencia entre las fallas utilizando técnicas de reconocimiento de patrones, en este caso Coeficiente de Correlación y Distancia Euclidiana.

En este trabajo se presentan los aspectos referentes al modelado de flujo en tuberías para detectar y localizar fugas, con un enfoque basado en observadores estado. El modelo de tubería está basado en las ecuaciones del Golpe de Ariete, discretizadas por diferencias finitas. Este requiere dos condiciones de frontera: presión o flujo a la entrada y salida de la tubería. Para mejorar el modelo, se modificó la forma de considerar el efecto de la fricción y la forma de introducir las condiciones de frontera. Se muestra, con simulaciones comparadas con datos reales, la importancia de considerar la variación del coeficiente de fricción, y además que la correcta selección de las condiciones de frontera, incluyendo las ecuaciones de la bomba y restricciones de flujo, permiten una mejor representación del comportamiento dinámico del flujo. Igualmente, se muestra que el modelo puede utilizarse para estimar el flujo de fuga y su posición utilizando observadores de estado, y se toma como ejemplo el filtro tipo Kalman Extendido. Se observó adicionalmente que, con el modelo obtenido, se puede trabajar con solo dos variables medidas: presión de salida y flujo de entrada, en lugar de las cuatro consideradas en trabajos anteriores.

Professionals must develop a series of necessary generic competences for the correct performance of their work, where those related to emotional self-regulation and coping with occupational psychosocial risk factors stand out. The present study examines the rol of perceived occupational coping self-efficacy as a modulating variable of burnout. We have found a differential modulator effect of self-efficacy on burnout in terms of working conditions; So that under some of that conditions (i.e. overload) self-efficacy protects against emotional exhaustion and under others (i.e. role ambiguity) self-efficacy can increase the probability of burnout occurrence. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) data from airborne laser scanning (ALS) and, more recently, digital aerial photogrammetry (DAP) have been successfully used to model forest attributes. While multi-temporal, wall-to-wall ALS data is not usually available, aerial imagery is regularly acquired in many regions. Thus, the combination of ALS and DAP data provide a sufficient temporal resolution to properly monitor forests. However, field data is needed to fit new forest attribute models for each 3D data acquisition, which is not always affordable. In this study, we examined whether transferability of growing stock volume (GSV) models may provide an improvement in the efficiency of forest inventories updating. We used two available ALS datasets acquired with different characteristics in 2009 and 2010, respectively, generated two DAP point clouds from imagery collected in 2010 and 2017, and utilized field data from two ground surveys conducted in 2009 and 2016-2017. We first analyzed the stability of point cloud derived metrics. Then, Support Vector Regression models based on the most stable metrics were fitted to assess model transferability by applying them to other datasets in four different cases: (1) ALS-ALS, (2) DAP-DAP temporal, (3) ALS-DAP and (4) ALS-DAP temporal. Some metrics were found to be enough stable in each case, so they could be used interchangeably between datasets. The application of models to other datasets resulted in unbiased predictions with relative root mean square error differences ranging from -8.27% to 14.59%. Results demonstrated that 3D-based GSV models may be transferable between point clouds of the same type as well as point clouds acquired using different technologies such as ALS and DAP, suggesting that DAP data may be used as a cost-efficient source of information for updating ALS-assisted forest inventories.

En este trabajo se hace un análisis de las diferentes fallas que se pueden presentar en los instrumentos de un proceso químico (válvula y transmisor). El método propuesto detecta y diagnostica el instrumento con problemas en el proceso. Un modelo de un proceso químico es usado para ver cómo trabaja el método propuesto, para diferenciar una falla de válvula de una falla de transmisor, se utiliza un análisis en el dominio wavelet; luego se mide la diferencia entre las fallas utilizando técnicas de reconocimiento de patrones, en este caso Coeficiente de Correlación y Distancia Euclidiana.This paper presents an approach to analyse different kinds of chemical processes instrumentation faults. The proposed approach makes a detection and diagnosis of the instrument worsening in the process. A chemical process model is used to show how the approach works, to differentiate valves and transmitter problems an analysis in the wavelet domain is presented along with pattern recognition procedures, such as correlation coefficient and Euclidean distance approaches.

Se presenta un Trabajo de Investigación, dentro del contexto de “Profesiones Asistenciales”, donde estudiamos el Estrés Laboral en su fase más avanzada y más concretamente los síndromes de Burnout (profesional quemado) y Mobbing (acoso moral en trabajo). El objetivo general es determinar el nivel del constructo Estrés Laboral, a través del estudio de estos síndromes, detectándose una alta incidencia del Síndrome de Burnout entre los docentes de secundaria. El instrumento utilizado, para realizar esta investigación, ha consistido en un protocolo de recogida de información autoadministrado que consta de: Registro de variables personales y de condiciones de trabajo; Inventario de Burnout de Maslach (MBI) e Inventario de terror psicológico de Leymann (LIPT). Finalmente se obtiene una alta incidencia de burnout, no se detecta un alto porcentaje de mobbing, no podemos descartar una posible relación entre burnout y mobbing y se establece el perfil de profesorado burnout.