Influencia de factores fósicos y químicos sobre la sobrevivencia de Pichia aislada de jarabe de glucosa

Yeasts belonging to the genus Pichia were isolated fr om glucose syrup samples. Yeasts were identified as P. anomala ( it is now Wickerhamomyces anomala) and P. guilliermondii. These strains did not metabolize the nutritive preservatives, potassium sorbate or sodium benzoate when these were used as the single carbon source. P. anomala grew in culture media containing up to 1200 mg/L of both preservatives. Critical temperature and time of exposure for its inactivation were 60 °C and 3 min, respectively. P. guilliermondii grew in media containing up to 1400 mg/L of both preservatives. Critical temperature and time for inactivation of this Pichia were 80 °C and 2 min. This strain was able to grow in a wide range of temperatures (5 to 30 °C), pH (2.5 to 5.5) and glucose concentrations (200 to 800 g/L). At 5 °C and 800 g/L glucose (osmotic pressure, 0.110 atm), P.guilliermndii gr ew poorly , with no cell death because of its ability to sporulate. We determined that P. guilliermondii is a potentially contaminating yeast able to develop in a variety of foods, especially those with low pH or with high sugar concentrations (glucose above 400g/L) such as refreshments, juices, syrups and confected fruits and it is resistant to both food preservatives and low temperatures (5°C).De muestras de jarabe de glucosa fueron aisladas levaduras que pertenecen al género Pichia. Estas fueron identificadas como P.anomala (actualmente Wickerha- momyces anomala) y P. guilliermondii, ambas cepas no metabolizan los conservantes alimenticios, sorbato de potasio o benzoato de sodio, al ser usados como única fuente de carbono. P. anomala desarrolló en medios de cultivo que contenían hasta 1200 mg/L de ambos conservantes. La temperatura y el tiempo crítico de exposición para su inactivación fueron 60 °C y 3 min, respectiva- mente. P.guilliermondii desarrolló en medios que contienen hasta 1400 mg/l de ambos conservantes. La to y el tiempo crítico de inactivación fueron 80 °C y 2 min. Esta cepa fue capaz de desarrollar en un amplio rango de temperaturas (5 a 30 °C), pH (2,5 a 5,5) y concentraciones de glucosa (200 a 800 g/L). A 5 °C y glucosa 800 g/L (presión osmótica, 0,110 atm), P. guilliermondii desarrolló pobremente sin que se produzca la muerte celular debido a su capacidad de esporular. Se deter- minó que P. guilliermondii, es una levadura potencialmente contaminante que puede desarrollarse en una variedad de alimentos, especialmente aquellos con bajo pH o altas concentraciones de azúcar (glucosa, > 400 g/L) como en gaseosas, jugos, jarabes y frutas confitadas, y es resistente a ambos conservantes y bajas to (5°C)Fil: Rubio, María Cristina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Biotecnología; ArgentinaFil: Navarro, Antonio Roberto. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin

Innovation, R&D Investment and Productivity in Chile

This paper uses two sources of information and different methodologies to analyze the causal effect of product and process innovation on productivity in the Chilean manufacturing industry during the past decade. In general, the evidence suggests there is not a contemporaneous effect of product innovation on productivity, but there is a positive effect of process innovation. This notsignificant effect of product innovation contrasts with evidence of studies for other countries. However, the results show the presence of lagged effects product innovation on productivity two years after innovation. Compared with the case of developed countries, this evidence might be consistent with a very slow process of “learning by doing” on the part of Chilean firms with regard to mastering new technologies. These slow and frequently uncertain gains in productivity could help to explain the low levels of investment in research and development (R&D) activities by Chilean firms.Productivity, Innovation, Investment, Research and development, Chile

A numerical approach for predicting flow-induced acoustics at near-stall conditions in an automotive turbocharger compressor

Se realiza un modelo CFD-3D de un compresor centrífugo. Se determina la configuración numérica adecuada para simular puntos de funcionamiento cercanos a bombeo. Se validan los resultados frente a ensayos experimentales realizados en cámara anecoica. Se analizan los resultados, justificando las características del ruido emitido por el compresor a partir de los patrones de flujo encontrados. En particular, se analiza el flujo en la holgura entre los álabes y la carcasa del compresor y en la parte posterior del rodete. Por último, se analiza la influencia de las geometrías aguas arriba del compresor en el ruido producido por éste.Navarro García, R. (2014). A numerical approach for predicting flow-induced acoustics at near-stall conditions in an automotive turbocharger compressor [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/44114TESISPremios Extraordinarios de tesis doctorale

Microlensing events in the Galactic bulge

For the first time we detected microlensing events at zero latitude in the Galactic bulge using the VISTA Variables in the Via Lactea Survey (VVV) data. We have discovered a total sample of N = 630 events within an area covering 20.7 sq. deg. Using the near-IR color magnitude diagram we selected N = 291 red clump sources, allowing us to analyse the longitude dependence of microlensing across the central region of the Galactic plane. We thoroughly accounted for the photometric and sampling efficiency. The spatial distribution is homogeneous, with the number of events smoothly increasing toward the Galactic center. We find a slight asymmetry, with a larger number of events toward negative longitudes than positive longitudes, that is possibly related with the inclination of the bar along the line of sight. We also examined the timescale distribution which shows a mean on 17.4 +- 1.0 days for the whole sample, and 20.7 +- 1.0 for the Red Clump subsample.Comment: Proceedings of the Fifteenth Marcel Grossman Meeting on General Relativity Edited by Elia Battistelli, Robert T. Jantzen, and Remo Ruffini. 6 pages, 3 figures, to be published in Open access e-book proceedings World Scientific, Singapore, 201

On the quantum stress tensor for extreme 2D Reissner-Nordstrom black holes

Contrary to previous claims, it is shown that the expectation values of the quantum stress tensor for a massless scalar field propagating on a two-dimensional extreme Reissner-Nordstrom black hole are indeed regular on the horizon.Comment: 5 pages, revtex, 1 figur

La representacion judicial de las victimas de delitos sexuales y el deber de proteccion en el sistema penal chileno

54 p.En esta memoria se realiza un análisis del sistema de protección a favor de las victimas contemplado en el ordenamiento jurídico chileno, particularmente, en la constitución política de la republica y en el código procesal penal. Para lograr el objetivo anterior se desarrollara una investigación jurídica dogmática del conjunto de normas que regulan este sistema de protección. El principal problema a desarrollar, es determinar la relación entre deber de protección y representación judicial de las victimas de delitos, respecto de la cual, demostrare que no existe tal relación normativa. Además, se analizara las modificaciones que pretende realizar el legislador, con la finalidad de corregir esta anormalidad jurídica, y por ultimo manifestar las razones por las cuales el legislador protege con más ímpetu a las victimas de delitos sexuales. ABSTRACT: In this research it will be developed an analysis of the protection system in favor of the victims referred in the Juridical Chilean Classification, particularly in the Political Constitution of the Republic and in the Procedural Penal Code. To reach the previous objective, it will be made a Juridical Dogmatic Research of the set of rules that regulate the protection system. The main problem developed is determinate the relation between protection duty and the judicial representation of the victims of crimes, for which I will demonstrate that does not exist a normative relation. Besides, I will analyzed the modifications that pretends to develop the legislator, with the finality of correct that situation, and finally demonstrate the reasons why is protected with more importance to the victims that suffer sexual abuses

Effects of the Background Turbulence on the Relaxation of Ion Temperature Anisotropy in Space Plasmas

Turbulence in space plasmas usually exhibits two regimes separated by a spectral break that divides the so called inertial and kinetic ranges. Large scale magnetic fluctuations are dominated by non-linear MHD wave-wave interactions following a -5/3 or -2 slope power-law spectrum. After the break, at scales in which kinetic effects take place, the magnetic spectrum follows a steeper power-law $k^{-\alpha}$ shape given by a spectral index $\alpha > 5/3$. Despite its ubiquitousness, the possible effects of a turbulent background spectrum in the quasilinear relaxation of solar wind temperatures are usually not considered. In this work, a quasilinear kinetic theory is used to study the evolution of the proton temperatures in an initially turbulent collisionless plasma composed by cold electrons and bi-Maxwellian protons, in which electromagnetic waves propagate along a background magnetic field. Four wave spectrum shapes are compared with different levels of wave intensity. We show that a sufficient turbulent magnetic power can drive stable protons to transverse heating, resulting in an increase in the temperature anisotropy and the reduction of the parallel proton beta. Thus, stable proton velocity distribution can evolve in such a way as to develop kinetic instabilities. This may explain why the constituents of the solar wind can be observed far from thermodynamic equilibrium and near the instability thresholds.Comment: 19 pages, 6 figures, accepted for publication in Frontiers in Physic

Statistical properties of volume in the Bitcoin/USD market

It is widely known that the volumes of limit orders and market orders display non-trivial statistical properties. For example, the sizes of volumes can take on many different values across several orders of magnitude, with a marked preference for whole numbers like 5, 10, 100. These studies have been centered on the volume of incoming orders or of realized transactions. In the present work we analyze the statistical properties of volumes stored at the best ask and best bid. We measured both dynamical properties as well as properties that do not directly depend on time. Of the properties found some are also present in the time series of price returns while others turn out to be particularly idiosyncratic and distinguish the stochastic nature of volume time series from that of price returns time series