La política económica del gobierno bolivariano

En este artículo vamos a tratar de presentar de la manera más sencilla y resumida posible las pretensiones y los logros de la política económica que ha llevado a cabo el gobierno bolivariano desde que Hugo Chávez llegara al poder teniendo en cuenta, sobre todo, la situación inicial y los objetivos que el propio gobierno se había ido proponiendo. Para ello, analizaremos los objetivos explícitos de los sucesivos programas y planes del gobierno venezolano y sus resultados macroeconómicos y sociales que se manifiestan en los indicadores disponibles

A Second Order Sliding Mode Controller with Predefined-Time Convergence

This paper presents the basis to design a well-suited control law which guarantees predefined-time convergence for a class of second-order systems. In contrast to the case of finite-time and fixed-time controllers, a predefined-time controller allows to set the bound of the convergence time, explicitly during the control design. Furthermore, in the case of no disturbance, the least upper bound of the convergence time can be predefined directly from the control definition. A Lyapunov-like characterization for predefined-time stability is performed. Numerical results are discussed to show the reliability of the proposed method.Consejo Nacional de Ciencia y Tecnologí

High pressure effects on the activities of cathepsins B and D of mackerel and horse mackerel muscle

We determined high pressure processing (HPP) effects on the activities of cathepsins B and D in the muscles of mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus). In mackerel, the cathepsin B activity decrease reached 40% at 450 MPa while in horse mackerel, low and intermediate pressures (150 and 300 MPa) caused an activity increase (30%) but at 450 MPa a decrease of up to 60%. In both species, cathepsin D activity increased after a 300 MPa treatment (up to 2-fold for mackerel and 60% for horse mackerel) and decreased on a 450 MPa treatment. The activity increase is probably due to HPP damage of lysosome releasing enzymes into the fish muscle. Based on the HPP effects on the activities of cathepsins B and D, 450 MPa may be used to reduce the proteolytic activity of cathepsin B prior to chilled or frozen storage of these fish speciesSupported by the Xunta de Galicia, Spain Project 10TAL402001PR, 2010-2012, and FCT (Portugal), European Union, QREN, FEDER and COMPETE thorough QOPNA research unit, Project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296. Also supported by he USDA National Institute of Food and Agriculture, Grants No. 2011-31200-06041 and 2012-31200-06041S

Sortase mutants with improved protein thermostability and enzymatic activity obtained by consensus design

Staphylococcus aureus sortase A (SaSrtA) is an enzyme that anchors proteins to the cell surface of Gram-positive bacteria. During the transpeptidation reaction performed by SaSrtA, proteins containing an N-terminal glycine can be covalently linked to another protein with a C-terminal LPXTG motif (X being any amino acid). Since the sortase reaction can be performed in vitro as well, it has found many applications in biotechnology. Although sortase-mediated ligation has many advantages, SaSrtA is limited by its low enzymatic activity and dependence on Ca2+. In our study, we evaluated the thermodynamic stability of the SaSrtA wild type and found the enzyme to be stable. We applied consensus analysis to further improve the enzyme's stability while at the same time enhancing the enzyme's activity. As a result, we found thermodynamically improved, more active and Ca2+-independent mutants. We envision that these new variants can be applied in conjugation reactions in low Ca2+ environments

Conservadurismo del resultado bajo las normas internacionales de contabilidad: un estudio comparado

El presente trabajo muestra que la adopción de la normativa del IASB en los países europeos ha contribuido a aumentar el conservadurismo del resultado de las empresas que las implantaron antes de ser obligatorias en 2005, acercando las medidas de conservadurismo a los niveles estadounidenses. Este no es el caso de las empresas de países menos desarrollados que han adoptado la normativa internacional. Para estas empresas, pese a la adopción de las NIC, el conservadurismo no ha aumentado. De hecho, no hay indicios de asimetría en el reconocimiento de noticias en el resultado. Además, parte del aumento en el conservadurismo observado en las empresas europeas desaparece si se controla de manera adecuada por sus características específicas

Conservadurismo del resultado contable bajo las Normas Internacionales de Contabilidad: Un estudio comparativo.

In this study we analyse whether the use of IASB standards affects the conservatism of earnings of the firms that adopt them. We compare the conservatism of firms by groups of firms/countries using or not IAS. Our results show that 1) Earnings conservatism is, as pointed out in prior research, more pronounced in common-law-based developed economies; 2) The voluntary use of IASB standards in Europe (prior to 2005) has significantly increased the measures of earnings conservatism in adopting firms, and 3) The use of IAS fails to improve the relevance and reliability of accounting information in emerging/developing countries, where enforcement and investor protection is lowEn este trabajo se analiza si el uso de las normas del IASB afecta al conservadurismo del resultado de las empresas que las adoptan. Para ello comparamos el conservadurismo por grupos de empresas/países que usan o no las normas internacionales (NIC). Nuestros resultados muestran que: 1) El conservadurismo del resultado es, tal y como pone de manifiesto la literatura previa, más pronunciado en los países desarrollados basados en el derecho común, 2) La adopción voluntaria de las normas del IASB en Europa (antes de 2005) aumentó significativamente las medidas de conservadurismo del resultado de las empresas que las adoptaron, y 3) El uso de las NIC no logró mejorar la relevancia/fiabilidad de la información contable en los países emergentes o en vías de desarrollo, donde la protección de los intereses de los inversores es escasa

Efecto de la adición de proteínas solubles recuperadas del agua de lavado de surimi de Pacific Whiting sobre las propiedades funcionales y mecánicas de surimi de Alaska pollock grado FA

Soluble proteins from surimi wash water (SWW) can be insolubilized by complexing with chitosan-alginate allowing its recovery and the reduction of the organic matter in the processing water discharged from surimi processing plants. The objective of this work was to evaluate the effect of adding soluble proteins recovered from Pacific whiting SWW on the mechanical and functional properties of commercial Alaska Pollock surimi grade FA. Levels evaluated were 0 (control), 10, 30 and 50 g insolubilized SWW solids/kg Alaska Pollock grade FA surimi. The mechanical and functional properties of Alaska Pollock surimi pastes and gels were characterized by texture profile analysis (TPA), puncture test, expressible water (EW) and color attributes. TPA and puncture test parameters increased significantly (P≤0.05) when 10–30 g/kg of soluble proteins from Pacific whiting SWW were added. EW values increased also, indicating a decrease of the water holding capacity. Color parameters showed that all surimi gels increased in redness, an undesirable effect in the production of Alaska Pollock grade FA surimiLas proteínas solubles del agua de lavado del surimi (ALS) pueden ser insolubilizadas por medio de la formación de complejos con quitosano y alginato. Su recuperación por este método permite reducir la materia orgánica en el agua de proceso. El objetivo de este trabajo fue evaluar el efecto de la adición de proteína soluble recuperada del ALS de Pacific whiting sobre las propiedades mecánicas y funcionales de surimi comercial de Alaska Pollock de grado FA. Los niveles de adición evaluados fueron 0 (control), 10, 30 y 50 g sólidos insolubilizados de ALS/kg de surimi de Alaska Pollock de grade FA. Las propiedades mecánicas y funcionales se caracterizaron por medio del análisis de perfil de textura (TPA), prueba de punción, agua extraíble y atributos de color. Los valores de los parámetros de TPA y prueba de punción incrementaron significativamente (P≤0.05) cuando se adicionaron de 10 a 30 g/kg de proteínas solubles de ALS de Pacific whiting. El agua extraíble también se incrementó, indicando un descenso de la capacidad de retención de agua. Los atributos de color indicaron que todos los geles de surimi incrementaron su color rojo, lo cual podría ser desfavorable para la producción de surimi de Alaska Pollock grado FAThis work was partially supported by Grant no. NA 16RG 1039 (Project no. R/SF-29) from the National Oceanic and Atmospheric Administration to the Sea Grant College Program at Oregon State University, and appropriations made by the Oregon State Legislature. Part of this study was supported by Grant no. TAMPS-2003-C02-14, FOMIXCONACYT, MéxicoS

A Note on Predefined-Time Stability

This note presents a new characterization for predefined-time-stable systems based on Lyapunov stability. In contrast to the previous results in predefined-time stability, the proposed characterization allows the construction of predefined-time stabilizing controllers with polynomial terms instead of exponential ones, removing the exponential nature hypothesis of predefined-time-stable systems. Moreover, the existing Lyapunov characterization of predefined-time stability is shown to be a consequence of the new theorem presented in this paper. Finally, the proposed approach is used for the construction of robust predefined-time stabilizing controllers for first-order systems. A simulation example shows the feasibility of the proposed methods.Consejo Nacional de Ciencia y Tecnologí

A Class of Continuous Predefined-Time Controllers

A class of continuous predefined-time controllers is designed in this paper. The control structure is built upon a class of comparison functions, whose features allow to analyze the predefined-time convergence property in the Lyapunov framework. Rather than providing exact predefined-time convergence to the equilibrium point, the proposed controller guarantees uniform predefined-time ultimate predefined boundedness of the solutions, i.e., the capability of setting an arbitrarily desired ultimate bound and an arbitrarily desired convergence time, through an appropriate selection of the controller parameters. Moreover, for a class of second-order systems, an additional analysis is carried out to show finite-gain input-output stability. The reliability of the proposed scheme is highlighted through numerical simulations in a representative example.ITESO, A.C