Melvin Sanchez

© 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.Reduced cell wall recalcitrance and increased C6 monosaccharide content are desirable traits for future biofuel crops, as long as these biomass modifications do not significantly alter normal growth and development. Mixed-linkage glucan, a cell wall polysaccharide only present in grasses and related species among flowering plants, is comprised of glucose monomers linked by both β-1,3 and β-1,4 bonds. Previous data have shown that constitutive production of MLG in barley severely compromises growth and development. Here, we used spatio-temporal strategies to engineer Arabidopsis thaliana plants to accumulate significant amounts of MLG in the cell wall by expressing the rice CslF6 MLG synthase using secondary cell wall and senescence-associated promoters. Results using secondary wall promoters were suboptimal. When the rice MLG synthase was expressed under the control of a senescence-associated promoter, we obtained up to four times more glucose in the matrix cell wall fraction and up to a 42% increase in saccharification compared to control lines. Importantly, these plants grew and developed normally. The induction of MLG deposition at senescence correlated with an increase of gluconic acid in cell wall extracts of transgenic plants in contrast to the other approaches presented in this study. MLG produced in Arabidopsis has an altered structure compared to the grass glucan, which likely affects its solubility, while its molecular size is unaffected. The induction of cell wall polysaccharide biosynthesis in senescing tissues offers a novel engineering alternative to enhance cell wall properties of lignocellulosic biofuel crops.

El objetivo de este estudio es analizar las investigaciones de pregrado en Literatura de una universidad peruana. Se realizó el mapeo sistemático de diez trabajos publicados entre el 2017 y 2022. Los resultados evidencian preferencia por la investigación en literatura peruana y que el género literario más estudiado es el narrativo. Se concluye que en los trabajos no se describen claramente los métodos científicos ni las metodologías de análisis literario; debido a su diversidad, a que los estudios literarios poseen una complejidad interdisciplinaria, y porque los esfuerzos educativos universitarios en investigación se centran en los últimos semestres.

El trabajo tiene los dos siguientes objetivos. En primer lugar, repasar la literatura más reciente sobre Intangibles y Capital Intelectual para poner de manifiesto los avances sobre estos temas y las lagunas que subsisten. En segundo lugar, presentar los retos a los que, a medio plazo, hay que hacer frente para incrementar la utilidad de este marco de análisis en la creación y difusión de conocimiento y en el diseño de políticas públicas. Dichos retos hacen referencia, básicamente, a la necesidad de contar con datos homogéneos, públicos y frecuentes para analizar las consecuencias de la existencia y gestión del Capital Intelectual en el desempeño de las organizaciones. Se sugieren los mecanismos para superar esos retos y las características que deben tener los necesarios acuerdos supranacionales que se habiliten al efecto.

New aspects of spectral fluctuations of (quantum) chaotic and diffusive systems are considered, namely autocorrelations of the spacing between consecutive levels or spacing autocovariances. They can be viewed as a discretized two point correlation function. Their behavior results from two different contributions. One corresponds to (universal) random matrix eigenvalue fluctuations, the other to diffusive or chaotic characteristics of the corresponding classical motion. A closed formula expressing spacing autocovariances in terms of classical dynamical zeta functions, including the Perron–Frobenius operator, is derived. It leads to a simple interpretation in terms of classical resonances. The theory is applied to zeros of the Riemann zeta function. A striking correspondence between the associated classical dynamical zeta functions and the Riemann zeta itself is found. This induces a resurgence phenomenon where the lowest Riemann zeros appear replicated an infinite number of times as resonances and sub-resonances in the spacing autocovariances. The theoretical results are confirmed by existing “data.” The present work further extends the already well known semiclassical interpretation of properties of Riemann zeros