1,721,131 research outputs found
Parameterized Model Order Reduction for Efficient Time and Frequency Domain Global Sensitivity Analysis of PEEC Circuits
No full textThis paper presents a new parameterized model order reduction technique to efficiently perform global time- and frequency-domain sensitivity analysis of electromagnetic systems over the design space of interest. The partial element equivalent circuit (PEEC) method is adopted to build the electromagnetic system model at a set of initial samples in the design space. The block Laguerre-SVD algorithm is proposed to reduce the size of the original equations of the PEEC-based equivalent circuit along with those describing the port voltage and current sensitivities. Then, a multivariate cubic spline interpolation method is used to build a parameterized compact model of port voltages and currents along with their corresponding sensitivities over the entire design space of interest. Finally, two numerical examples are presented, which confirm the accuracy and efficiency of the proposed method
Male sterility in birdsfoot trefoil (Lotus corniculatus L.).
No full textThis paper describes six male steriles
in birdsfoot trefoil. Data on the following characters
were recorded on these plants and on two male
fertile plants: chromosome number, presence of
pollen at tripping, percentage of irregularly shaped
anthers, percentage of anthers with acetocarmine
stainable pollen inside, maximum range of percentage
of pollen fertility among anthers within a flower
presenting pollen, and percentage of pod setting
with selfing. All male steriles showed a somatic
chromosome number typical of the species. All
were indehiscent and complete control of pollination
occurred in all but one. They differed in percentage
of irregular anthers, percentage of anthers
with stainable pollen inside, and range of percentage
of pollen fertility among anthers within a flower.
Indehiseence in flowers having some pollen inside
the anthers was probably due to lack of internal
pressure. It is concluded that these genotypes
can be of value in breeding birdsfoot trefoil
HISTOLOGICAL ANALYSIS OF COCOA SEEDS (THEOBROMA CACAO L.)
No full textThe cocoa (Theobroma cacao L.) is experiencing a considerable appreciation in recent years from the nutritional point of view. In addition to its economic importance, the cardioprotective effect of flavonoids in cocoa powder and dark chocolate was confirmed (Keen et al., 2005). To acquire, therefore, more information about the substances present in the various tissues of the seed of this species is of significant interest.
The aim of this research was the localization of macronutrients, such as lipids, proteins and carbohydrates in the different tissues/organs of the cocoa seed, by hystochemical analysis and microscopic observations. The presence and localization of flavonoids were also investigated. Seeds were collected from a fresh fruit of cocoa and portions (2-3 mm of size) of the seed coat, endosperm, cotyledons and embryo were embedded in epoxy resin. In cyto-histological studies, semithin sections were stained with toluidine blue, while to localize macronutrients PAS staining and the osmium treatment were carried out.
Our studies confirmed that all portions of the mature seeds contribute to store macronutrients. In the teguments soluble polysaccharides were detected, in the endosperm the polysaccharides and lipids; polyphenols and polysaccharide
Patterns of anatomy differentation, growth and physiological activity following Paclobutrazol application in chestnut
No full textCorrelation between sexual reproduction in Phragmites australis and die-back syndrome
No full textThe common reed Phragmites australis (Cav.) Trin. ex Steud. (syn. P. communis Trin.) is a member of Poaceae with a widespread distribution in both the hemispheres, in different habitat types from river/lake shores, wetlands, coastlands and estuarine habitats, to ruderal, disturbed and even urban areas, hence it is considered a sub-cosmopolite species (Bjork 1967, Haslam 1973, Ostendorp 1993, Brix 1999a) In the last decades, reeds are dying back at a fast rate in sizeable areas of Europe, with significant impacts on important wetland functions (biodiversity, stability of river and lake margins, water quality) and local economy (Den Hartog et al. 1989, Van Der Putten 1997, Brix 1999b). Similar symptoms have been detected even in central Italy (Gigante et al. 2011).
Besides ecological, morphological or anatomical parameters studies concerning some reproductive aspects might also be interesting in order to detect the health condition of reed-dominated ecosystems. In all the plant species the flower biology can be a good indicator of the health condition as the seed production and the seed viability. In plants exhibiting both vegetative and sexual reproduction, the energy allocation can be shifted from one to the other strategy in response to environmental stress; it is well known that sexual reproduction decreases the vulnerability of a population to disturbances and biotic stresses by increasing the genetic variability (Lei 2010).
On this ground, we took into account the reproductive features of a declining reed stand in central Italy, where the die-back syndrome was recently detected (Gigante et al. 2011), with the aims to extend knowledge on sexual reproduction in P. australis and to highlight links between sexual reproduction and die-back symptoms. In this frame, cyto-histological analyses of inflorescences at different developmental stages were carried out in permanent plots where morphological investigation and histochemical analyses were also carried out to verify pollen and seed viability. An interesting link between some decline symptoms and the rate of spikelets containing at least one viable seed was observed. In detail, it appears that higher rates of viable seeds are recorded in the declining reed stands
Morpho-histological characterization and nutritional properties of prickly pear (Opuntia ficusindica L. Mill)
No full textOpuntia ficus indica (L.) is a large genus of succulent shrubs native to Mexico. In 16th century it was
introduced into several continents and is now widely grown in the warmer parts of the world. It has been
shown that the prickly pear fruit is very rich in vitamins, minerals, amino acids and in sugars. Another
important compositional factor of prickly pear is the presence of pigments, such as betalains, which make
the fruit and its products particularly attractive. Betalains are vacuolar pigments present in all varieties of
reported O. ficusindica. Their main function in the plant is to attract animals for pollen transfer facilitating
plant propagation and to protect against UV radiation. Two betalain derivatives are present in cactus-pears:
betacyanin, which gives the red-purple colour, and betaxanthin, which gives a yellow-orange colour. These
pigments have important antioxidant activities without toxic effects to humans. Given the considerable
interest aroused by this species, the aim of our research was to study the morphological and cyto-histological
characteristics of the fruit from two different varieties of the prickly pear typical of Sicily (Italy):”
Sanguigna” and “Muscaredda” or “Sciannarina”.Some functional compounds of prickly pear such as the
betalains, the carotenoids and chlorophyll (a and b) were also quantified. There were no cyto-histological
differences between the fruits of the two considered varieties; instead the content of betacyanins and
chlorophyll was very different
L’ossido nitrico come segnale molecolare nel pathway di trasduzione della risposta allo stress da ozono in piante di Nicotiana tabacum (cv. BelW3)
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