5,603 research outputs found
Metodologia para manuseio de Mycosphaerella musiocola em laboratório.
Introdução; Histórico da Sigatoka-amarela da bananeira; Biologia e Sintomatologia; A produção de conídios e ascósporos e sua relação com fatores climáticos; Isolamento de Mycospharella musiocola; Inoculação de Mycospharella musiocola em plantas teste; Considerações finais; Referências.bitstream/item/54426/1/Doc-198-final.pd
Epidemiological measurements in banana genotypes inoculated with Mycosphaerella musicola.
In order to define the most important variables in disease progression, it is necessary to know the details of the monocycle of the pathogen. Incubation periods and establishment of Sigatoka leaf spot, caused by Mycosphaerella musicola, are strongly influenced by climatic factors and by genotype
Interferência da iluminância nos parâmetros monocíclicos do patossistema Mycosphaerella musicola - Musa spp.
A bananicultura está distribuída em praticamente todo o mundo. A sigatoka-amarela é uma das doenças de maior importância de alguns países tropicais, e pode ter sua severidade aumentada em condições ambientais favoráveis (2, 3, 5)
Morphological analysis of Yarrowia lipolytica under stress conditions through image processing
Yarrowia lipolytica is an aerobic microrganism capable to produce important metabolites, has
an intense secretory activity which drives efforts to be employed in industry (as a biocatalyst),
in molecular biology and genetics studies. Dimorphism is refeered to fungi ability to growth
in two distinct forms, usually as single oval cells os as a filament and to be reversible between
each one. The cell shape is controlled by environmental factors and has been seeked by some
authors [1,2,3].
Y. lipolytica has been considered an adequate model for dimorphism studies in yeasts since it
has an efficient system for transformation and is easy to distinct between its morphological
forms, on opposite to S. cerevisiae that do not produce true filaments and exhibits pseudohyphae
growth under nitrogen limited conditions. Y. lipolytica has an hyphae diameter
corresponding 60 to 100% of its single cell stage [4,5]. It is believed that Y. lipolytica
dimorphism is related to defense mechanism from adverse conditions.
The aim of this work resides on investigate morphological changes in Y. lipolytica under
thermal and oxidative stress conditions. Yarrowia lipolytica (IMUFRJ 50682) was cultivated
in YPD medium (glucose 2%, peptone 0.64%, yeast extract 1%) at 29oC and 160 rpm.
Thermal stress experiments were carried employing a temperature shift (37oC / 1 h.). For
oxidative ones, an addition of H2O2 was used to reach final concentration of 10mM. Both
stress conditions were applied at exponential growth phase. Morphology was observed in a
optic microscope (Axiolab, Zeiss) and cell characteristics were determined employing image
processing analysis (Matlab v. 6.1, The Mathworks Inc.) and comparisons were carried on to
a control system.
A net increase around 22% on hyphae formation was detected as well as a significant
increment in its length in relation to control system, when both thermal and oxidative stress
was applied. The results herein obtained drives to consider a possible relationship between
dimorphism and a cell response mechanism to stress conditions.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação para a Ciência e a Tecnologia (FCT); CAPES
Function Merging by Sequence Alignment
Resource-constrained devices for embedded systems are becoming increasingly important. In such systems, memory is highly restrictive, making code size in most cases even more important than performance. Compared to more traditional platforms, memory is a larger part of the cost and code occupies much of it. Despite that, compilers make little effort to reduce code size. One key technique attempts to merge the bodies of similar functions. However, production compilers only apply this optimization to identical functions, while research compilers improve on that by merging the few functions with identical control-flow graphs and signatures. Overall, existing solutions are insufficient and we end up having to either increase cost by adding more memory or remove functionality from programs. We introduce a novel technique that can merge arbitrary functions through sequence alignment, a bioinformatics algorithm for identifying regions of similarity between sequences. We combine this technique with an intelligent exploration mechanism to direct the search towards the most promising function pairs. Our approach is more than 2.4x better than the state-of-the-art, reducing code size by up to 25%, with an overall average of 6%, while introducing an average compilation-time overhead of only 15%. When aided by profiling information, this optimization can be deployed without any significant impact on the performance of the generated code
Differential evolution for the offline and online optimization of fed-batch fermentation processes
The optimization of input variables (typically feeding trajectories over
time) in fed-batch fermentations has gained special attention, given the economic impact
and the complexity of the problem. Evolutionary Computation (EC) has been a
source of algorithms that have shown good performance in this task. In this chapter,
Differential Evolution (DE) is proposed to tackle this problem and quite promising
results are shown. DE is tested in several real world case studies and compared with
other EC algorihtms, such as Evolutionary Algorithms and Particle Swarms. Furthermore,
DE is also proposed as an alternative to perform online optimization, where the
input variables are adjusted while the real fermentation process is ongoing. In this case,
a changing landscape is optimized, therefore making the task of the algorithms more
difficult. However, that fact does not impair the performance of the DE and confirms
its good behaviour.(undefined
Evolutionary algorithms for optimal control in fed-batch fermentation processes
In this work, Evolutionary Algorithms (EAs) are used to achieve optimal feedforward control in a recombinant bacterial fed-batch
fermentation process, that aims at producing a bio-pharmaceutical product.
Three diferent aspects are the target of the optimization procedure: the feeding trajectory (the amount of substrate introduced in a bioreactor per time unit), the duration of the fermentation and the initial conditions
of the process. A novel EA with variable size chromosomes and using real-valued representations is proposed that is capable of simultaneously optimizing the aforementioned aspects. Outstanding productivity levels
were achieved and the results are validated by practice
HyFM: Function Merging for Free
Function merging is an important optimization for reducing code size. It merges multiple functions into a single one, eliminating duplicate code among them. The existing state-of-the-art relies on a well-known sequence alignment algorithm to identify duplicate code across whole functions. However, this algorithm is quadratic in time and space on the number of instructions. This leads to very high time overheads and prohibitive levels of memory usage even for medium-sized benchmarks. For larger programs, it becomes impractical.
This is made worse by an overly eager merging approach. All selected pairs of functions will be merged. Only then will this approach estimate the potential benefit from merging and decide whether to replace the original functions with the merged one. Given that most pairs are unprofitable, a significant amount of time is wasted producing merged functions that are simply thrown away.
In this paper, we propose HyFM, a novel function merging technique that delivers similar levels of code size reduction for significantly lower time overhead and memory usage. Unlike the state-of-the-art, our alignment strategy works at the block level. Since basic blocks are usually much shorter than functions, even a quadratic alignment is acceptable. However, we also propose a linear algorithm for aligning blocks of the same size at a much lower cost. We extend this strategy with a multi-tier profitability analysis that bails out early from unprofitable merging attempts. By aligning individual pairs of blocks, we are able to decide their alignment’s profitability separately and before actually generating code.
Experimental results on SPEC 2006 and 2017 show that HyFM needs orders of magnitude less memory, using up to 48 MB or 5.6 MB, depending on the variant used, while the state-of-the-art requires 32 GB in the worst case. HyFM also runs over 4.5×× faster, while still achieving comparable code size reduction. Combined with the speedup of later compilation stages due to the reduced number of functions, HyFM contributes to a reduced end-to-end compilation time
Emergence of magnetism in graphene materials and nanostructures
Magnetic materials and nanostructures based on carbon offer unique
opportunities for future technological applications such as spintronics. This
article reviews graphene-derived systems in which magnetic correlations emerge
as a result of reduced dimensions, disorder and other possible scenarios. In
particular, zero-dimensional graphene nanofragments, one-dimensional graphene
nanoribbons, and defect-induced magnetism in graphene and graphite are covered.
Possible physical mechanisms of the emergence of magnetism in these systems are
illustrated with the help of computational examples based on simple model
Hamiltonians. In addition, this review covers spin transport properties,
proposed designs of graphene-based spintronic devices, magnetic ordering at
finite temperatures as well as the most recent experimental achievements.Comment: tutorial-style review article -- 18 pages, 19 figure
Radial stability analysis of the continuous pressure gravastar
Radial stability of the continuous pressure gravastar is studied using the
conventional Chandrasekhar method. The equation of state for the static
gravastar solutions is derived and Einstein equations for small perturbations
around the equilibrium are solved as an eigenvalue problem for radial
pulsations. Within the model there exist a set of parameters leading to a
stable fundamental mode, thus proving radial stability of the continuous
pressure gravastar. It is also shown that the central energy density possesses
an extremum in rho_c(R) curve which represents a splitting point between stable
and unstable gravastar configurations. As such the rho_c(R) curve for the
gravastar mimics the famous M(R) curve for a polytrope. Together with the
former axial stability calculations this work completes the stability problem
of the continuous pressure gravastar.Comment: 17 pages, 5 figures, References corrected, minor changes wrt v1,
matches published versio
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