8,842 research outputs found
SORBITOL SYNTHESIS FROM A LACTOBACILLUS CASEI FOOD-GRADE STRAIN USING METABOLIC ENGINEERING
No full textSorbitol is a sugar alcohol that is assumed to have important physiological properties for human health. It could replace high-calorie sugars such as glucose, lactose or sucrose in food products with equivalent sweetness and taste. The synthesis of sorbitol in situ during fermentation of dairy products may result in a good strategy to obtain fermented products with extra health-promoting value. A food-grade recombinant strain of Lactobacillus casei (BL232) was constructed by the integration of a D-Sorbitol-6-phosphate dehydrogenase-encoding gene (gutF) in the chromosomal lactose operon. gutF expression followed the same regulation as that of the lac genes, that is, repressed by glucose and induced by lactose. BL232 cells were induced with lactose, and using 13C-nuclear magnetic resonance analysis, sorbitol was detected by addition of glucose to resting cells. Inactivation of the L-lactate dehydrogenase gene in BL232 led to higher sorbitol production, suggesting that the novel route provides an alternative pathway for NAD+ regeneration. Since sorbitol is not absorbed in the small intestine, it could reach the colon and there it could selectively stimulate the multiplication or activity of beneficial bacteria. Results showing the influence of sorbitol on the intestinal microbiota of rats will be presente
New Production and the Global Carbon Cycle
No full textThe export of newly produced organic carbon from the surface ocean and its regeneration at depth account for an estimated three-quarters of the vertical ΣCO2 gradient shown in Fig. 1 (Volk and Hoffert, 1985). If these processes, often referred to as the “biological pump,” had ceased operating during the pre-industrial era, the increase in surface ΣCO2 resulting from upward mixing of high ΣCO2 deep waters would have raised atmospheric pCO2 from 280 ppm to the order of 450 ppm (Sarmiento and Toggweiler, 1984) over a period of centuries. Vertical exchange, which gives an estimated upward flux of 100 GtC/yr (Fig. 2), works continuously to bring about just such a scenario. The biological pump prevents it by stripping out about 10 GtC/yr, so that the water arriving at the surface has a concentration equal to that which is already there
Perspectives of the River Plate around the time of Rosas : an analysis based upon the personal correspondence, private memoirs and published accounts of British settlers, as well as works by creole authors
No full textThis thesis draws inspiration from the emergence of cultural studies as an academic
pursuit, in addition to the current renewal of interest in the relationship between
literary works and their socio-cultural milieux, to bring together an assortment of
textual traces pertaining to the River Plate around the era of Juan Manuel de Rosas,
governor of Buenos Aires and de facto dictator of Argentina for most of the period
1829-1852. The main texts analysed range from private documents relating to two
Scottish settler families, through accounts published by British citizens with first-hand
knowledge of the region (Un inglés, Cinco años en Buenos Aires and
Beaumont, Travels in Buenos Ayres and the Adjacent Provinces), to three influential
pieces of early Argentinian literature (Echeverria's El matadero, Mármol's Amalia
and Sarmiento's Facundo). One justification of this apparently eclectic approach lies
in the prominence accorded to the incomer in the thought of liberal Platine
intellectuals, a concern evinced in their literary production.
The methodology involves examining the representation of certain
fundamental topics across this range of written artefacts, observing frequent points of
thematic convergence amongst the various texts. In this fashion, I construct an image
of the River Plate region around the Rosas period, whilst also appraising the degree
to which early British settlers matched the idealized notion of the immigrant present
in liberal creole writings.
The study is divided into four main chapters, supplemented by an
introduction, conclusion and appendix. The first chapter summarizes the historical
context of the young Platine republics; the second deals with the themes of society,
community and family, the third focuses upon religion; the fourth considers
perspectives of politics, dictatorship and civil war. The appendix consists of an
unpublished settler autobiography, a remarkable account of the tribulations faced on
a daily basis in the developing Argentina
Partial characterization of graphs having a single large Laplacian eigenvalue
No full textFil: Grippo, Luciano Norberto. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina.Fil: Grippo, Luciano Norberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Safe, Martín M. Universidad Nacional del Sur. Departamento de Matemática; Argentina.Fil: Allem, L. Emilio. Universidade Federal do Rio Grande do Sul. Instituto de Matemática; Brazil.Fil: Cafure, Antonio. Universidad Nacional de General Sarmiento. Instituto del Desarrollo Humano; Argentina.Fil: Trevisan, Vilmar. Universidade Federal do Rio Grande do Sul; Brasil.Fil: Dratman, Ezequiel. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina.The parameter σ(G) of a graph G stands for the number of Laplacian eigenvalues
greater than or equal to the average degree of G. In this work, we address the
problem of characterizing those graphs G having σ(G) = 1. Our conjecture is that
these graphs are stars plus a (possible empty) set of isolated vertices. We establish
a link between σ(G) and the number of anticomponents of G. As a by-product,
we present some results which support the conjecture, by restricting our analysis to
cographs, forests, and split graphs
La Escuela sin la religión de mi mujer
No full textSarmiento's reply to 'Escuela sin religión' by Nicolás Avellaneda, published 1883. In reference to the 'Ley de Educación Común', passed in 1884, Sarmiento defends secular education and the new laws concerning religious teaching at public schools. Material in this pamphlet was taken from newspaper articles published in Buenos Aires in 1883, after Avellaneda's publication. The editor is signed 'A. M. G', possibly Angel M. Giménez, who is noted on the back page as a contributor to the same publication serie
Response of the ocean natural carbon storage to projected twenty-first-century climate change
No full textThe separate impacts of wind stress, buoyancy fluxes, and CO2 solubility on the oceanic storage of natural carbon are assessed in an ensemble of twentieth- to twenty-first-century simulations, using a coupled atmosphere–ocean–carbon cycle model. Time-varying perturbations for surface wind stress, temperature, and salinity are calculated from the difference between climate change and preindustrial control simulations, and are imposed on the ocean in separate simulations. The response of the natural carbon storage to each perturbation is assessed with novel prognostic biogeochemical tracers, which can explicitly decompose dissolved inorganic carbon into biological, preformed, equilibrium, and disequilibrium components. Strong responses of these components to changes in buoyancy and winds are seen at high latitudes, reflecting the critical role of intermediate and deep waters. Overall, circulation-driven changes in carbon storage are mainly due to changes in buoyancy fluxes, with wind-driven changes playing an opposite but smaller role. Results suggest that climate-driven perturbations to the ocean natural carbon cycle will contribute 20 Pg C to the reduction of the ocean accumulated total carbon uptake over the period 1860–2100. This reflects a strong compensation between a buildup of remineralized organic matter associated with reduced deep-water formation (+96 Pg C) and a decrease of preformed carbon (?116 Pg C). The latter is due to a warming-induced decrease in CO2 solubility (?52 Pg C) and a circulation-induced decrease in disequilibrium carbon storage (?64 Pg C). Climate change gives rise to a large spatial redistribution of ocean carbon, with increasing concentrations at high latitudes and stronger vertical gradients at low latitudes
Selectarum interpretationum liber octauus, qui De legatis secundo inscribitur / authore D. Francisco Sarmiento...
No full textError de fol., 179 por 178, 178 por 179, 171 por 180En port. grab. xil. esc. episcopalTexto a dos col.Enc. Perg.Sign.: [ ]2, A-E6, F8, G-I6, L-Z6, Aa-Gg6, Hh4, A
The intensity of a field simulated marine heat wave differentially modulates the transcriptome expression of Posidonia oceanica from warm and cold environments
No full textMarine Heat Waves (MHWs) occurrence has been increasing in the Mediterranean Sea. The effects of field simulated MHWs of different intensity (medium and high temperature) on the transcriptome expression of the endemic seagrass Posidonia oceanica were evaluated considering different origins of the plant. The aim of the study was reached through a common garden transplant experiment in the North-west of Sardinia (Italy), where two P. oceanica meadows characterized by different thermal regimes (cold and warm) were chosen. MHWs were simulated in front of a power plant, that creates a natural laboratory by releasing warm water in the sea. Differential gene expression and GO enrichment analyses highlighted differences in the transcriptomic profiles of plants from cold and warm environments suggesting that the MHWs induced different levels of stress due to different tolerance to the heat event. Plants from both origins activated processes to achieve protein homeostasis, but only cold plants activated an antioxidant defense and altered sugar metabolism, both indicators of heat stress. Within plants of the same origin, a different response to MHW intensity was also detected: while warm plants showed the most complex response at high temperature rather than at medium temperature, cold plants seemed to better cope with the medium temperature intensity rather than with high temperature
Local environment modulates whole-transcriptome expression in the seagrass Posidonia oceanica under warming and nutrients excess
No full textThe intensification of anomalous events of seawater warming and the co-occurrence with local anthropogenic stressors are threatening coastal marine habitats, including seagrasses, which form extensive underwater meadows. Eutrophication highly affects coastal environments, potentially summing up to the widespread effects of global climate changes. In the present study, we investigated for the first time in seagrasses, the transcriptional response of different plant organs (i.e., leaf and shoot apical meristem, SAM) of the Mediterranean seagrass Posidonia oceanica growing in environments with a different history of nutrient enrichment. To this end, a mesocosm experiment exposing plants to single (nutrient enrichment or temperature increase) and multiple stressors (nutrient enrichment plus temperature increase), was performed. Results revealed a differential transcriptome regulation of plants under single and multiple stressors, showing an organ-specific sensitivity depending on plants' origin. While leaf tissues were more responsive to nutrient stress, SAM revealed a higher sensitivity to temperature treatments, especially in plants already impacted in their native environment. The exposure to stress conditions induced the modulation of different biological processes. Plants living in an oligotrophic environment were more responsive to nutrients compared to plants from a eutrophic environment. Evidences that epigenetic mechanisms were involved in the regulation of transcriptional reprogramming were also observed in both plants’ organs. These results represent a further step in the comprehension of seagrass response to abiotic stressors pointing out the importance of local pressures in a global warming scenario
Lateral movements in Rayleigh–Taylor instabilities due to frontiers. Experimental study
No full textRevista con referatoFil: D'Onofrio, Alejandro Gustavo. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina.Fil: D'Onofrio, Alejandro Gustavo. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; Argentina.Fil: D'Onofrio, Alejandro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Binda, Leonardo David. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina.Fil: Zalts, Anita. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina.Lateral movements of the fingers in Rayleigh-Taylor hydrodynamic instabilities at the interface between two fluids are studied. We show that transverse movements appear when a physical boundary is present; these phenomena have not been explained until now. The boundary prevents one of the fluids from crossing it. Such frontiers can be buoyancy driven as, for example, the frontier to the passage of a less dense solution through a denser solution or when different aggregation states coexist (liquid and gaseous phases). An experimental study of the lateral movement velocity of the fingers was performed for different Rayleigh numbers (Ra), and when oscillations were detected, their amplitudes were studied. Liquid-liquid (L–L) and gas-liquid (G–L) systems were analysed. Aqueous HCl and Bromocresol Green (sodium salt, NaBCG) solutions were used in L–L experiments, and CO2 (gas) and aqueous NaOH, NaHCO3, and CaCl2 solutions were employed for the G–L studies. We observed that the lateral movement of the fingers and finger collapses near the interface are more notorious when Ra increases. The consequences of this, for each experience, are a decrease in the number of fingers and an increase in the velocity of the lateral finger movement close to the interface as time evolves. We found that the amplitude of the oscillations did not vary significantly within the considered Ra range. These results have an important implication when determining the wave number of instabilities in an evolving system. The wave number could be strongly diminished if there is a boundary
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