Morpho-physiological analysis of adaptive responses of common bean (Phaseolus vulgaris L.) to drought stress. Thesis (Ph.D.)

Common bean (Phaseolus vulgaris L.) is the most important food legume in the diet of poor people in the tropics. This legume is cultivated by small farmers and is usually exposed to unfavorable conditions with minimum use of inputs. Drought and low soil fertility, especially phosphorus (P) and nitrogen (N) deficiencies, are major limitations to bean yield in smallholder systems. Beans can derive part of their required N from the atmosphere through symbiotic nitrogen fixation (SNF). Drought stress severely limits SNF ability of plants. Identification of traits associated with drought resistance contributes to improving the process of designing bean genotypes adapted to these conditions. Field studies were conducted at the International Center for Tropical Agriculture (CIAT), Palmira, Colombia to determine the relationship between grain yield and different parameters in elite lines selected for drought resistance over the past decade. The selected traits were effective use of water (EUW), canopy biomass, remobilization of photosynthates to grain (pod partitioning index, harvest index and pod harvest index) and SNF ability. Moreover, in field trials we also validated the use of 15N natural abundance in grain tissue to quantify phenotypic differences in SNF ability for its implementation in breeding programs aiming to improve SNF in common bean. Carbon isotope discrimination (CID) was used for estimation of water use efficiency (WUE) and effective use of water (EUW). A set of 36 bean genotypes belonging to the Middle American gene pool were evaluated under field conditions with two levels of water supply (irrigated and rainfed) over two seasons. Additionally, a greenhouse study was conducted at CIAT using plastic cylinders with soil inserted into PVC pipes, to determine the relationship between grain yield and different root parameters such as total root length, fine root production and visual root growth rate in same group of elite lines under drought stress. Eight bean lines (NCB 280, NCB 226, SEN 56, SCR 2, SCR 16, SMC 141, RCB 593 and BFS 67) were identified as resistant to drought stress. Resistance to terminal drought stress was positively associated with EUW combined with a deeper and vigorous root system, better plant growth, and superior mobilization of photosynthates to pod and seed production, but negatively associated with days to flowering and days to physiological maturity. Based on phenotypic differences in CID, leaf stomatal conductance, canopy biomass and grain yield under drought stress, the tested lines were classified into two groups, water savers and water spenders. These groups also differ in their root characteristics, water spenders with a vigorous and deeper root system and water savers genotypes with a moderate to shallow root system and more presence of fine roots. We used 15N natural abundance method to compare SNF ability estimated from shoot tissue sampled at mid-pod filling growth stage vs. grain tissue sampled at harvest. The results showed a significant positive correlation between nitrogen derived from the atmosphere (Ndfa), estimated using shoot tissue at mid-pod filling, and Ndfa estimated using grain tissue at harvest. The method showed phenotypic variability in SNF ability under both drought and irrigated conditions. A significant reduction in SNF ability was observed under drought stress. We suggest that the method of estimating Ndfa using grain tissue (Ndfa-G) can be applied in bean breeding programs to improve SNF ability. Using this method of Ndfa-G, we identified four bean lines (RCB 593, SEA 15, NCB 226 and BFS 29) that combine greater SNF ability with higher grain yield under drought stress. These lines could serve as potential parents to further improve SNF ability of common bean. Better SNF ability under drought stress was related with superior presence of thick roots. Superior N uptake from the soil was associated with a large root system with more presence of fine roots. Pod harvest index, grain CID and Ndfa using grain tissue could be a useful selection criterion in breeding programs to select for drought resistance in common bean

Engineering directed excitonic energy transfer

We provide an intuitive platform for engineering exciton transfer dynamics. We show that careful consideration of the spectral density, which describes the system-bath interaction, leads to opportunities to engineer the transfer of an exciton. Since excitons in nanostructures are proposed for use in quantum information processing and artificial photosynthetic designs, our approach paves the way for engineering a wide range of desired exciton dynamics. We carefully describe the validity of the model and use experimentally relevant material parameters to show counter-intuitive examples of a directed exciton transfer in a linear chain of quantum dots

Simulating chemistry using quantum computers

The difficulty of simulating quantum systems, well-known to quantum chemists, prompted the idea of quantum computation. One can avoid the steep scaling associated with the exact simulation of increasingly large quantum systems on conventional computers, by mapping the quantum system to another, more controllable one. In this review, we discuss to what extent the ideas in quantum computation, now a well-established field, have been applied to chemical problems. We describe algorithms that achieve significant advantages for the electronic-structure problem, the simulation of chemical dynamics, protein folding, and other tasks. Although theory is still ahead of experiment, we outline recent advances that have led to the first chemical calculations on small quantum information processors.Comment: 27 pages. Submitted to Ann. Rev. Phys. Che

The confrontation between Mayans and the Iriarte with respect to the Latin grammars

En la historiografía tradicional, y a propósito del pleito de las gramáticas latinas, generalmente se ha presentado a Mayans como una víctima inerme de las intrigas de los Iriarte, y esta imagen coincide con la que don Gregorio a menudo presentó de sí mismo. Sin embargo, un análisis de este enfrentamiento en relación con las otras polémicas en las que resultó implicado el valenciano pone de manifiesto que los hechos deben ser interpretados en un contexto más amplio y más complejo que trasciende los enfrentamientos y las meras ambiciones personales, y que también caracteriza a la sociedad y la cultura españolas del siglo XVIII: el reformismo borbónico, la renovación de las enseñanzas del latín, el clientelismo político y la lucha de facciones y las nuevas formas de socialización de los literatos. Esta interpretación sugiere la necesidad de una historiografía de la lingüística de carácter hermenéutico.In traditional historiography, and with regard to the litigation of the Latin grammars, usually presented to Mayans as defenseless victims of the machinations of the Iriarte, and this picture agrees with that Don Gregorio often presented itself. However, an analysis of this conflict in relation to the other controversies in which it was implied the valencian shows that the facts must be interpreted in a broader context and more complex that transcends mere confrontations and personal ambitions, and that also characterizes the Spanish society and culture of the eighteenth century: the Bourbon reforms, the renewal of the teaching of Latin, the political patronage and factional fighting and the new forms of socialization of the writers

Metodologia sugerida para estimar o volume e a carga de poluentes gerados em uma granja de suínos.

bitstream/CNPSA/15662/1/cot332.pd

Prevention and Treatment of Acute Stroke in the Nonagenarians and Beyond : Medical and Ethical Issues

Peer reviewedPostprin

The relative abundance of wheat Rubisco activase isoforms is post‑transcriptionally regulated

Diurnal rhythms and light availability affect transcription–translation feedback loops that regulate the synthesis of photosynthetic proteins. The CO2-fixing enzyme Rubisco is the most abundant protein in the leaves of major crop species and its activity depends on interaction with the molecular chaperone Rubisco activase (Rca). In Triticum aestivum L. (wheat), three Rca isoforms are present that differ in their regulatory properties. Here, we tested the hypothesis that the relative abundance of the redox-sensitive and redox-insensitive Rca isoforms could be differentially regulated throughout light–dark diel cycle in wheat. While TaRca1-β expression was consistently negligible throughout the day, transcript levels of both TaRca2-β and TaRca2-α were higher and increased at the start of the day, with peak levels occurring at the middle of the photoperiod. Abundance of TaRca-β protein was maximal 1.5 h after the peak in TaRca2-β expression, but the abundance of TaRca-α remained constant during the entire photoperiod. The redox-sensitive TaRca-α isoform was less abundant, representing 85% of the redox-insensitive TaRca-β at the transcript level and 12.5% at the protein level. Expression of Rubisco large and small subunit genes did not show a consistent pattern throughout the diel cycle, but the abundance of Rubisco decreased by up to 20% during the dark period in fully expanded wheat leaves. These results, combined with a lack of correlation between transcript and protein abundance for both Rca isoforms and Rubisco throughout the entire diel cycle, suggest that the abundance of these photosynthetic enzymes is post-transcriptionally regulated

HBM, present and future of HPC based on FPGAs

In the past decades, advances in the speed of commodity CPUs have far out-paced advances in memory latency. Mainmemory access is therefore increasingly a performance bottleneck for many computer applications, including HPC embedded systems. This translates into unprecedented memory performance requirements in critical systems that the commonly used DRAM memories struggle to provide. High-Bandwidth Memory (HBM) can satisfy these requirements offering high bandwidth, low power and highintegration capacity features. However, it remains unclear whether the predictability and isolation properties of HBM are compatible with the requirements of critical embedded systems. In our research, a deep characterization of the HBM for its use in MEEP applications is performed