774 research outputs found
The Role of Prior Knowledge in Peer Tutorials: Rethinking the Study of Transfer in Writing Centers
Noncommutative Korteweg deVries and modified Korteweg deVries Hierarchies via Recursion Methods
Here, noncommutative hierarchies of nonlinear equations are studied. They represent a generalization to the operator level of corresponding hierarchies of scalar equations, which can be obtained from the operator ones via a suitable projection. A key tool is the application of BĂ€cklund transformations to relate different operator-valued hierarchies. Indeed, in the case when hierarchies in 1+1-dimensions are considered, a âBĂ€cklund chartâ depicts links relating, in particular, the Kortewegâde Vries (KdV) to the modified KdV (mKdV) hierarchy. Notably, analogous links connect the hierarchies of operator equations. The main result is the construction of an operator soliton solution depending on an infinite-dimensional parameter. To start with, the potential KdV hierarchy is considered. Then BĂ€cklund transformations are exploited to derive solution formulas in the case of KdV and mKdV hierarchies. It is remarked that hierarchies of matrix equations, of any dimension, are also incorporated in the present framework
Picocyanobacteria distribution in the Ebro Estuary (Spain)
The stratified estuary of the Ebro River is located on the Mediterranean coast of Spain. From samples obtained in 6 sampling campaigns between July 1999 and February 2000 from the last 18 km of Ebro River, the abundance of picocyanobacteria was estimated by epifluorescence microscopy. The abundance of picocyanobacteria reached 93.7 x106 cells Lâ1 in the river mouth (station R1) below the surface, in October 1999. In deeper layers of salt wedge area stations (near the river mouth), we could observe higher concentrations of marine cyanobacteria. This study offers comments about the abundance and distribution in cyanobacteria
Biochemical, Physiological and Anatomical Mechanisms of Adaptation of Callistemon citrinus and Viburnum lucidum to NaCl and CaCl2 Salinization
Callistemon citrinus and Viburnum lucidum are very appreciated and widespread ornamental shrubs for their abundant flowering and/or brilliant foliage. The intrinsic tolerance to drought/salinity supports their use in urban areas and in xeriscaping. Despite adaptive responses of these ornamental species to sodium chloride (NaCl) have been extensively explored, little is known on the effects of other salt solution, yet iso-osmotic, on their growth, mineral composition and metabolism. The present research aimed to assess responses at the biochemical, physiological and anatomical levels to iso-osmotic salt solutions of NaCl and CaCl2 to discriminate the effects of osmotic stress and ion toxicity. The two ornamental species developed different salt-tolerance mechanisms depending on the salinity sources. The growth parameters and biomass production decreased under salinization in both ornamental species, independently of the type of salt, with a detrimental effect of CaCl2 on C. citrinus. The adaptive mechanisms adopted by the two ornamental species to counteract the NaCl salinity were similar, and the decline in growth was mostly related to stomatal limitations of net CO2 assimilation rate, together with the reduction in leaf chlorophyll content (SPAD index). The stronger reduction of C. citrinus growth compared to V. lucidum, was due to an exacerbated reduction in net photosynthetic rate, driven by both stomatal and non stomatal limitations. In similar conditions, V. lucidum exhibited other additional adaptive response, such as modification in leaf functional anatomical traits, mostly related to the reduction in the stomata size allowing plants a better control of stomata opening than in C. citrinus. However, C. citrinus plants displayed an increased ability to retain higher Cl- levels in leaves than in roots under CaCl2 salinity compared to V. lucidum, thus, indicating a further attempt to counteract chloride toxicity through an increased vacuolar compartmentalization and to take advantages of them as chip osmotica
PD-0498: Use of STAT in prostate cancer: correlation with risk factors and identification of residual cohort
n/
Anthocyanins are Key Regulators of Drought Stress Tolerance in Tobacco
Abiotic stresses will be one of the major challenges for worldwide food supply in the near future. Therefore, it is important to understand the physiological mechanisms that mediate plant responses to abiotic stresses. When subjected to UV, salinity or drought stress, plants accumulate specialized metabolites that are often correlated with their ability to cope with the stress. Among them, anthocyanins are the most studied intermediates of the phenylpropanoid pathway. However, their role in plant response to abiotic stresses is still under discussion. To better understand the effects of anthocyanins on plant physiology and morphogenesis, and their implications on drought stress tolerance, we used transgenic tobacco plants (AN1), which over-accumulated anthocyanins in all tissues. AN1 plants showed an altered phenotype in terms of leaf gas exchanges, leaf morphology, anatomy and metabolic profile, which conferred them with a higher drought tolerance compared to the wild-type plants. These results provide important insights for understanding the functional reason for anthocyanin accumulation in plants under stress
Hard-disk computer simulations -- a historic perspective
We discuss historic pressure computations for the hard-disk model performed
since 1953, and compare them to results that we obtain with a powerful
event-chain Monte Carlo and a massively parallel Metropolis algorithm. Like
other simple models in the sciences, such as the Drosophila model of biology,
the hard-disk model has needed monumental effort to be understood. In
particular, we argue that the difficulty of estimating the pressure has not
been fully realized in the decades-long controversy over the hard-disk
phase-transition scenario. We present the physics of the hard-disk model, the
definition of the pressure and its unbiased estimators, several of which are
new. We further treat different sampling algorithms and crucial criteria for
bounding mixing times in the absence of analytical predictions. Our definite
results for the pressure, for up to one million disks, may serve as benchmarks
for future sampling algorithms. A synopsis of hard-disk pressure data as well
as different versions of the sampling algorithms and pressure estimators are
made available in an open-source repository.Comment: 21 pages, 13 figures, open-source repositor
Chemical Eustress Elicits Tailored Responses and Enhances the Functional Quality of Novel Food Perilla frutescens
Consumer demand for fresh and functional horticultural products is on the rise. Perilla frutescens, L. Britt (Lamiaceae) is a potential specialty/niche crop for consumption and therapeutic uses with high contents of phenolic and volatile compounds. Plant growth, mineral composition, polyphenol proïŹle and aroma volatile components of two perilla genotypes in response to salinity (non-salt control, 10, 20 or 30 mM NaCl) applied as chemical eustressor were assessed. Salinity suppressed growth and yield of both genotypes, although the red-pigmented genotype was less sensitive than the green-pigmented one. Mild (10 mM NaCl) and moderate (20 and 30 mM NaCl) salinity suppressed foliar potassium, magnesium, nitrate and chlorophyll a concentrations of both genotypes and increased the levels of rosmarinic acid, total polyphenols and target aroma volatilecomponents. Greenperillashowedhigheryieldandbiomassproductionandhighercontentof protein,drymatter,calcium,magnesium,perillaketoneandcis-jasmone,whereasredperillaexhibited higher content of potassium, chlorophyll a, rosmarinic acid, total polyphenols, perilla aldehyde and benzaldehyde. OurïŹndingssupportthatchemicaleustressorssuchasmildtomoderatesalinityoffer valuable means to manipulate phytochemical and aroma proïŹles
- âŠ