The CreC regulator of Escherichia coli, a new target for metabolic manipulations

The CreBC (carbon source-responsive) two-component regulation system of Escherichia coli affects a number of functions, including intermediary carbon catabolism. The impacts of different creC mutations (a ΔcreC mutant and a mutant carrying the constitutive creC510 allele) on bacterial physiology were analyzed in glucose cultures under three oxygen availability conditions. Differences in the amounts of extracellular metabolites produced were observed in the null mutant compared to the wild-type strain and the mutant carrying creC510 and shown to be affected by oxygen availability. The ΔcreC strain secreted more formate, succinate, and acetate but less lactate under low aeration. These metabolic changes were associated with differences in AckA and LdhA activities, both of which were affected by CreC. Measurement of the NAD(P)H/NAD(P)+ ratios showed that the creC510 strain had a more reduced intracellular redox state, while the opposite was observed for the ΔcreC mutant, particularly under intermediate oxygen availability conditions, indicating that CreC affects redox balance. The null mutant formed more succinate than the wild-type strain under both low aeration and no aeration. Overexpression of the genes encoding phosphoenolpyruvate carboxylase from E. coli and a NADH-forming formate dehydrogenase from Candida boidinii in the ΔcreC mutant further increased the yield of succinate on glucose. Interestingly, the elimination of ackA and adhE did not significantly improve the production of succinate. The diverse metabolic effects of this regulator on the central biochemical network of E. coli make it a good candidate for metabolic-engineering manipulations to enhance the formation of bioproducts, such as succinate.Fil: Godoy, Manuel Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Nikel, Pablo Ivan. Consejo Superior de Investigaciones Científicas; EspañaFil: Cabrera Gomez, José Gregorio. Unviversidad de San Pablo; BrasilFil: Pettinari, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentin

Before the public space: a history of green and open spaces in Rosario city (1900-1940)

Este trabajo parte de constatar la proliferación del concepto de espacio público en el lenguaje político, proyectual y cultural urbano actual. Posteriormente, se interroga acerca de si esa multiplicación y derrame del concepto de las últimas décadas tuvo algún correlato o equivalente en el pasado. El artículo comprueba que, al menos en la ciudad de Rosario, el espacio público como designación aplicable a un espacio urbano específico es un fenómeno relativamente nuevo, que no puede remontarse más allá de las tres últimas décadas. Este estudio se propone reconstruir históricamente las designaciones y los sentidos producidos alrededor de y atribuidos a los espacios verdes en tanto dispositivos urbanos. El higienismo, el paisajismo y el urbanismo son las tres formaciones discursivas y momentos históricos que construyen el acceso para reflexionar acerca de la relación que los espacios verdes y los espacios libres, en tanto dispositivos higiénicos, paisajísticos y urbanísticos, plantean con los significantes actualmente asignados al espacio público. Se demuestra que entre los espacios verdes y los espacios públicos existe una relación marcada por la diferencia, la discontinuidad y el desplazamiento.From the proliferation of public space in the political, projective and cultural urban languages, this work analyses the projection of this concept in historical terms. The article notes that, strictly speaking, the public space as a designation applicable to a specific urban space is a relatively new phenomenon, which can’t go back beyond the last three decades. This study aims to reconstruct historically produced designations and cultural meanings around and attributed to green spaces in both urban devices. Matrices hygienist, landscaper and urbanism are the three discursive formations and historical genealogical moments used to reflect about the relationship that green spaces and open spaces, while hygienic, landscape and urban devices pose with signifiers currently assigned the public space. It is shown that between green spaces and public spaces there is a relationship marked by difference, discontinuity and displacement.Fil: Roldan, Diego Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Humanidades y Artes. Centro de Estudios Culturales Urbanos; ArgentinaFil: Godoy, Sebastián David. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Humanidades y Artes. Centro de Estudios Culturales Urbanos; Argentin

On dynamic quasi-bifurcation of simple shell-like systems under impulsive loads

The nonlinear dynamic response and buckling of a simple, two degree of freedom system is investigated in this work under an impulsive load that simulates a nearby detonation-like explosion. The model considered in this work was originally studied by other researchers to explore static buckling. The system includes force and moment springs in much the same way as membrane and bending effects develop in shell structures. The static response is first obtained to evaluate bifurcation states and nonlinear equilibrium paths including geometric imperfections. The dynamic problem is modeled using Lagrange equation of motion involving the total potential and kinetic energies. The nonlinear dynamic response under impulsive load is next computed for the perfect configuration under increasing load levels. The presence of quasi-bifurcations is detected using stability coefficients based on second order derivatives of the total potential energy. For a given load level, it is found that one stability coefficient vanishes at the first maximum in the displacement versus time trajectory, at which the system passes through a state of zero velocity. This occurs for the same displacement configuration as in the static buckling mode. The results show that quasi-bifurcation loads thus obtained are independent of the amplitude of the geometric imperfection considered but display high sensitivity to changes in the membrane to bending stiffness ratio. Extensions of the present model to account for the behavior of oil storage tanks under loads due to nearby explosions are suggested.Fil: Ameijeiras, Mariano Pablo. Universidad Nacional de Córdoba; ArgentinaFil: Godoy, Luis Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin

Quasi-bifurcation and Imperfection-sensitivity of Cylindrical Shells under Pressures due to an Explosion

The static and dynamic behavior of a horizontal cylindrical shell (as used to store fuels in tanks) is investigated in this work by means of computational modeling. Under a distributed pressure commonly used to model effects due to explosions, the geometrically nonlinear behavior is explored to identify bifurcation and limit points along the static equilibrium path, and the associated displacements. Critical load reductions due to imperfections are found in the order of 25%. The dynamic analysis is next presented to identify the possibility of reaching a quasi-bifurcation. It is found that the first peak in the transient response at which the displacement reaches the same value as in the limit static case occurs for a load which is about 3.5 times the static bifurcation load. The velocity is zero at this state and is identified as a quasi-bifurcation, at which the shell is expected to display a static instability. Imperfection-sensitivity of the quasi-bifurcation load is found to be of the same order as the static one. This is the first quasi-bifurcation study of a shell to identify dynamic buckling due to a nearby explosion.Fil: Ameijeiras, Mariano Pablo. Universidad Nacional de Córdoba; ArgentinaFil: Godoy, Luis Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin

A cloud based WSN remote laboratory for user training

This paper presents a WSN remote laboratory prototype aimed at user training. The prototype has been deployed on a Cloud Computing infrastructure, in order to take advantage of the benefits that this technology can provide to remote laboratories. An analysis of the state of the art allows to specified the features required for a remote laboratory intended to be applyed in user training. In this paper, the main results of this analysis are presented. Then, the implementation of the main modules that compose the remote laboratory, and the analysis that led to chose a deployment based on Cloud Computing are presented. Some proof of concept experiments to test the applicability to user training were performed and the results are presented in this paper.Área: Tecnología en Educación.Red de Universidades con Carreras en Informática (RedUNCI

A Nomadic Testbed for Teaching Computer Architecture

A nomadic laboratory or testbed, based on Raspberry Pi 3 computers and Arduino microcontrollers, has been developed in order to teach subjects related to computer architecture. The testbed can be transported to the classroom. Students can access it through the available network, which can be a wireless LAN, wired LAN o a custom network. The student can access without constraints to the platforms, therefore there are a wide range of possible experiments. This laboratory was used during 2017 for practical works in the course Introduction to Technology, and during 2018 in the course Computers Architecture at Universidad Nacional of Cuyo. Some of the experiments that are been carried out by students are: to explore and analyse the architecture of the computers through Linux commands, write and run programs on different programing languages, input and output operations through memory mapped addressing and isolated addressing, write interrupt service routines in order to service interrupts, multithreading programing, explore memory maps, CPU features, etc. This paper describes the testbed architecture, experiments performed by students in the mentioned subjects, present the students feedback, and describes the possible methods in order to integrate it to a remote laboratory.XVII Workshop Tecnología Informática Aplicada en Educación (WTIAE)Red de Universidades con Carreras en Informática (RedUNCI

A Nomadic Testbed for Teaching Computer Architecture

A nomadic laboratory or testbed, based on Raspberry Pi 3 computers and Arduino microcontrollers, has been developed in order to teach subjects related to computer architecture. The testbed can be transported to the classroom. Students can access it through the available network, which can be a wireless LAN, wired LAN o a custom network. The student can access without constraints to the platforms, therefore there are a wide range of possible experiments. This laboratory was used during 2017 for practical works in the course Introduction to Technology, and during 2018 in the course Computers Architecture at Universidad Nacional of Cuyo. Some of the experiments that are been carried out by students are: to explore and analyse the architecture of the computers through Linux commands, write and run programs on different programing languages, input and output operations through memory mapped addressing and isolated addressing, write interrupt service routines in order to service interrupts, multithreading programing, explore memory maps, CPU features, etc. This paper describes the testbed architecture, experiments performed by students in the mentioned subjects, present the students feedback, and describes the possible methods in order to integrate it to a remote laboratory.XVII Workshop Tecnología Informática Aplicada en Educación (WTIAE)Red de Universidades con Carreras en Informática (RedUNCI