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Search Results: 1 - 10 of 402462 matches for " W. S. Costa "
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Partículas esferoidais associadas ao vírus do mosaico das nervuras da mandioca
Kitajima, E. W.;Costa, A. S.;
Bragantia , 1966, DOI: 10.1590/S0006-87051966000100018
Abstract: spheroidal particles, 50-60 m? in diameter, were found in quick preparations and in ultra-thin sections for electron microscopy, from leaves of cassava plants infected with the vein mosaic (cvmv). they were not found in preparations made from healthy plants, nor in symptomless leaves of infected plants, and are considered as representing the virus. in ultra-thin sections of leaf tissues, cvmv particles were found dispersed in certain areas of the cytoplasm, rich in ribosomes, but poor in other cytoplasmic organelles, where sporadical small bundles of dense fibrils (7-10 m?x 100-300 m?) occur. dense and fine granular masses (0.3-3 ?,in diameter) were seen in a few instances, associated with the particles. it seems likely that both fibrils and the dense masses are primarily involved in the cvmv synthesis.
Microscopia electr?nica de microrganismos do tipo micoplasma nos tecidos de milho afetado pelo enfezamento e nos órg?os da cigarrinha vectora portadora
Kitajima, E. W.;Costa, A. S.;
Bragantia , 1972, DOI: 10.1590/S0006-87051972000100006
Abstract: corn stunt in s?o paulo state is usually of minor importance during normal summer crops but might induce significant losses if corn is planted late in the season. it is transmitted by leaf - hopper dalbulus maidisde l. & w. and two different forms of this disease have been recognized the chlorotic, similar to the rio grande type of the u.s., and the red, resembling the mesa central type of mexico. electron microscopic examination of tissues from both affected plants or leafhopper reared on diseased plants, demonstrated the presence of pleomorphic, mycoplasma-like bodies, consistently associated with the corn stunt, which probably represent the causal agent the latter. no significant difference could be observed in the morphology of these mycoplasma-like bodies associated with the two disease types or with the insect vector. in the affected plants, these corpuscles were only found in the sieve tubes; in the insect body they were detected in several types of tissues of different organs - intestine, malphigian tubules, muscle, nervous ganglion, salivary gland, fat body, epidermis. in the insect cells, the pleomorphic bodies occurred either scattered in the cytoplasm or in cytoplasmic cavities bounded by membrane.
Bladder Neck Morphologic Changes and Clinical Correlation of Smokers Submitted to Radical Prostatectomy  [PDF]
L. C. N. Araujo, W. S. Costa, F. O. Vilar, S. V. C. Lima, F. J. B. Sampaio
Open Journal of Urology (OJU) , 2013, DOI: 10.4236/oju.2013.36043
Abstract:

Introduction: Smoking is an important risky factor to many diseases, affecting arterial system, skin and urogenital system, including bladder neck stenosis. Its effect on bladder neck has not been described. Objective: Evaluate possible morphological changes caused by nicotine in the bladder neck. Material and Method: Fragments of bladder neck of 16 patients were submitted to stereological analysis, and those patients are divided into two groups, one of smokers and the other of non-smokers with 7 and 9 patients, respectively. After 90 days of surgery, they were submitted to free uroflowmetry and data analyzed by T test, having statistical significance with P < 0.05. Results: An increase of 63.26% in the amount of fibers in the elastic system of the smokers group was observed, a reduction of 35.96% in the thickness of arteries, as well as an increase of IPSS and decrease of maximum flow in uroflowmetry, all with statistical significance. Discussion: Laboratorial changes are similar to those found in other studies with different tissues, such as skin, in which those findings are related to premature ageing. Clinical results, though statistically significant, do not have clinical consistence because the study was meant to morphological analysis. Conclusion: Smoking increases the

Lack of Relationship between Testicular Echotexture and Seminal Characteristics in Adult Texel Rams  [PDF]
Mariana A. G. Urt, Edwin W. B. Bakarji, Fábio J. C. Faria, Elisvania F. Santos, Deiler S. Costa
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.98065
Abstract: The objective of this study was to determine the minimum representative area to evaluate testicular echotexture parenchyma and to identify the correlations between the intensity of pixels of the testicular parenchyma and the fibrosis score with the physical and morphological characteristics of the ejaculate of Texel rams. The study used 88 Texel rams, aged between 10 and 12 months, and reared in a semi-extensive system. The animals underwent breeding soundness evaluation (BSE) and ultrasound of the testicles. The images were transferred to a computer where they were defined in areas of 400, 1600, 3600, and 6400 mm2, after which the average intensity of the pixels of each image of the testicular regions was evaluated. A testicular fibrosis score was assigned in order to quantify the frequency of fibrotic lesions. In relation to the intensity of pixels of the predetermined regions, only the area of 400 mm2 presented a difference (P < 0.05), with the area of 1600 mm2 being the smallest area that best represented the testicular parenchyma. There were no correlations between the intensity of pixels of the testicular parenchyma and the fibrosis score with the physical and morphological characteristics of the ejaculate of the rams.
Persistence in the Zero-Temperature Dynamics of the Random Ising Ferromagnet on a Voronoi-Delaunay lattice
F. W. S. Lima,R. N. Costa Filho,U. M. S. Costa
Physics , 2002,
Abstract: The zero-temperature Glauber dynamic is used to investigate the persistence probability $P(t)$ in the randomic two-dimensional ferromagnetic Ising model on a Voronoi-Delaunay tessellation. We consider the coupling factor $J$ varying with the distance $r$ between the first neighbors to be $J(r) \propto e^{-\alpha r}$, with $\alpha \ge 0$. The persistence probability of spins flip, that does not depends on time $t$, is found to decay to a non-zero value $P(\infty)$ depending on the parameter $\alpha$. Nevertheless, the quantity $p(t)=P(t)-P(\infty)$ decays exponentially to zero over long times. Furthermore, the fraction of spins that do not change at a time $t$ is a monotonically increasing function of the parameter $\alpha$. Our results are consistent with the ones obtained for the diluted ferromagnetic Ising model on a square lattice.
Critical behavior of the 3D-Ising model on a poissonian random lattice
F. W. S. Lima,U. M. S. Costa,R. N. Costa Filho
Physics , 2005,
Abstract: The single-cluster Monte Carlo algorithm and the reweighting technique are used to simulate the 3D-ferromagnetic Ising model on three dimensional Voronoi-Delaunay lattices. It is assumed that the coupling factor $J$ varies with the distance $r$ between the first neighbors as $J(r) \propto e^{-ar}$, with $a \ge 0$. The critical exponents $\gamma/\nu$, $\beta/\nu$, and $\nu$ are calculated, and according to the present estimates for the critical exponents, we argue that this random system belongs to the same universality class of the pure three-dimensional ferromegnetic Ising model.
Morfologia do vírus do mosaico do pic?o
Kitajima, Elliot W.;Carvalho, Ana Maria B.;Costa, A. S.;
Bragantia , 1961, DOI: 10.1590/S0006-87051961000100013
Abstract: electron microscopical observations were made on exudates obtained from plants of bidrus pilosa, chenopodium amaranticolor leonolis nepaetifolia, helianthus annums. nicotiana tabucum, cassia occidentalis, chenopodium ambrosioides, and physalis floridona infected with a virus that induces mosaic on the first named species. the presenes of a flexible thread with a normal length 720 mm. x 12-13 mm was recorded in the exudates from the: diseased plants, but not in those from the healthy ones, and is considered to represent the causal virus.
Inclus?es intracelulares associadas à "espiga branca" do trigo
Kitajima, E. W.;Caetano, V. R.;Costa, A. S.;
Bragantia , 1971, DOI: 10.1590/S0006-87051971000200002
Abstract: light microscopic examination of epidermal strips from leaves of wheat (triticum sativuml.) showing typical symptoms of the white spike (ws) disease, demonstrated the constant occurrence of huge, fibrous and whorled intracellular inclusions. occasionally cells adjacent to those having inclusions contained needle-like formations. the whorled inclusions appeared in ultrathin section profiles as loose aggregates of threadlike elements, 7-10 m? in diameter and of indeterminable length, within the cytoplasm. they seem to represent filamentous particles found in leaf dip preparations from affected plants, in situ. nucleolus hypertrophy, chloroplast degeneration and changes in endoplasmic reticulum were frequently noticed in affected tissues. occasionally small crystalline inclusions were found nearby or within the nucleus. the presence of these fibrous, whorled inclusions associated to ws condition, reinforces the suggested viral etiology, due to the similarity of these inclusions with virus aggregates found in tissues infected with several other viruses of the beet yellows virus group. besides symptomatology, the particle and inclusion morphology of rice "hoja blanca" virus are very similar to ws of wheat, suggesting that both diseases are induced by viruses of the same complex. the ease with which the inclusions are detected in epidermal strips, constitutes a quick and secure method to diagnose the ws disease.
Morfologia das partículas do vírus do anel do piment?o
Kitajima, E. W.;Oliveira, A. R.;Costa, A. S.;
Bragantia , 1969, DOI: 10.1590/S0006-87051969000100001
Abstract: tubular particles, about 25 m? wide, with an axial channel 4 m? in diameter, were found in leaf dip or purified preparations and also within tissues, from plants infected with pepper ringspot virus (prsv), but not in uninoculated control plants. the particle length determinations showed two prevalent types of particles in vitro, respectively with ca. 55 m? and 200 m? in normal length. these values were independent of the virus isolate, host plant or preparative procedures for electron microscopy employed. in thin section profiles, a dense rim was observed bordering the axial channel, in cross section of particles stained with uranyl acetate, which might represent the location of the viral nucleic acid in the virion. the long, 200 m?, particles can be separated from the short, 55 m? particles through sucrose gradient density ultracentrifugation, when it can be demonstrated that only the longer particles are infective. incubation of purified preparations with ribonuclease and/or trypsin, did not affect infectivity or the structure of the virions. however, in some experiments, the trypsin treatment induced an end-to-end aggregation of the particles. purified preparations lose infectivity after being heated for 10 minutes at 65-70°c. simultaneously a generalized degradation of virions is noticeable. the end product of this degradation is a powdery material, composed of granules 30-40 ao in diameter. in ultrathin sections of prsv-infected tissues, ordered aggregates of particles, similar to those found in vitro,were observed in the cytoplasm. such inclusions consisted of long (200 m?) particles only. in no instance, groups of typical 55 m?, short particles were found, and this suggests that they are fragments of the longer, 200 m?. particles, rather than products of self multiplication.
Microscopia electr?nica de inclus?es citoplas máticas e altera??es celulares associadas ao vírus do mosaico da cenoura
Camargo, I. J. B.;Kitajima, E. W.;Costa, A. S.;
Bragantia , 1971, DOI: 10.1590/S0006-87051971000100004
Abstract: a virus, inducing mosaic and malformation of carrot leaves (daucus carota l.), was found in piedade, sp. it was termed carrot mosaic virus (cmv), and is both mechanically and aphid transmitted. morphologically it belongs to the potato virus y group (15m? x 740m?). electron microscopic examination of thin sections of leaf tissues from carrot or coriander (coriandrum sativum l.) infected with cmv demonstrated the presence of cytoplasmic inclusions, usually in the form of dense bands. they could reach sizes up to 0.2? x 4? and were detectable even under light microscopic examination. these bands, at higher magnification, showed to be built up of thin lamella (10-15m? thick), closely apposed. occasionally individual or group of lamella appeared to loose from the bands, producing other type of profile, such as pin wheels and rings. cmv particles were sometimes observed in the vicinity of these inclusions, often laying parallel to their surface. these inclusions are identical to those observed in tissues infected with other components of the potato y virus group, and their detection seems to corroborate the previous inclusion of cmv in this group, basead on particle morphology. besides these cytoplasmic inclusions, some cells contained a large number of vesicles in the cytoplasm, apparently associated with golgi complex activity.
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