995 resultados para Morphological model
Resumo:
Mathematical morphology addresses the problem of describing shapes in an n-dimensional space using the concepts of set theory. A series of standardized morphological operations are defined, and they are applied to the shapes to transform them using another shape called the structuring element. In an industrial environment, the process of manufacturing a piece is based on the manipulation of a primitive object via contact with a tool that transforms the object progressively to obtain the desired design. The analogy with the morphological operation of erosion is obvious. Nevertheless, few references about the relation between the morphological operations and the process of design and manufacturing can be found. The non-deterministic nature of classic mathematical morphology makes it very difficult to adapt their basic operations to the dynamics of concepts such as the ordered trajectory. A new geometric model is presented, inspired by the classic morphological paradigm, which can define objects and apply morphological operations that transform these objects. The model specializes in classic morphological operations, providing them with the determinism inherent in dynamic processes that require an order of application, as is the case for designing and manufacturing objects in professional computer-aided design and manufacturing (CAD/CAM) environments. The operators are boundary-based so that only the points in the frontier are handled. As a consequence, the process is more efficient and more suitable for use in CAD/CAM systems.
Resumo:
The article describes some concrete problems that were encountered when writing a two-level model of Mari morphology. Mari is an agglutinative Finno-Ugric language spoken in Russia by about 600 000 people. The work was begun in the 1980s on the basis of K. Koskenniemi’s Two-Level Morphology (1983), but in the latest stage R. Beesley’s and L. Karttunen’s Finite State Morphology (2003) was used. Many of the problems described in the article concern the inexplicitness of the rules in Mari grammars and the lack of information about the exact distribution of some suffixes, e.g. enclitics. The Mari grammars usually give complete paradigms for a few unproblematic verb stems, whereas the difficult or unclear forms of certain verbs are only superficially discussed. Another example of phenomena that are poorly described in grammars is the way suffixes with an initial sibilant combine to stems ending in a sibilant. The help of informants and searches from electronic corpora were used to overcome such difficulties in the development of the two-level model of Mari. The variation of the order of plural markers, case suffixes and possessive suffixes is a typical feature of Mari. The morphotactic rules constructed for Mari declensional forms tend to be recursive and their productivity must be limited by some technical device, such as filters. In the present model, certain plural markers were treated like nouns. The positional and functional versatility of the possessive suffixes can be regarded as the most challenging phenomenon in attempts to formalize the Mari morphology. Cyrillic orthography, which was used in the model, also caused problems. For instance, a Cyrillic letter may represent a sequence of two sounds, the first being part of the word stem while the other belongs to a suffix. In some cases, letters for voiced consonants are also generalized to represent voiceless consonants. Such orthographical conventions distance a morphological model based on orthography from the actual (morpho)phonological processes in the language.
Resumo:
The use of planktonic foraminifera in paleoceanographic studies relies on the assumption that morphospecies represent biological species with ecological preferences that are stable through time and space. However, genetic surveys unveiled a considerable level of diversity in most morphospecies of planktonic foraminifera. This diversity is significant for paleoceanographic applications because cryptic species were shown to display distinct ecological preferences that could potentially help refine paleoceanographic proxies. Subtle morphological differences between cryptic species of planktonic foraminifera have been reported, but so far their applicability within paleoceanographic studies remains largely unexplored. Here we show how information on genetic diversity can be transferred to paleoceanography using Globorotalia inflata as a case study. The two cryptic species of G. inflata are separated by the Brazil-Malvinas Confluence (BMC), a major oceanographic feature in the South Atlantic. Based on this observation, we developed a morphological model of cryptic species detection in core top material. The application of the cryptic species detection model to Holocene samples implies latitudinal oscillations in the position of the confluence that are largely consistent with reconstructions obtained from stable isotope data. We show that the occurrence of cryptic species in G. inflata, can be detected in the fossil record and used to trace the migration of the BMC. Since a similar degree of morphological separation as in G. inflata has been reported from other species of planktonic foraminifera, the approach presented in this study can potentially yield a wealth of new paleoceanographical proxies.
Resumo:
This study presents the results of Raman spectroscopy applied to the classification of arterial tissue based on a simplified model using basal morphological and biochemical information extracted from the Raman spectra of arteries. The Raman spectrograph uses an 830-nm diode laser, imaging spectrograph, and a CCD camera. A total of 111 Raman spectra from arterial fragments were used to develop the model, and those spectra were compared to the spectra of collagen, fat cells, smooth muscle cells, calcification, and cholesterol in a linear fit model. Non-atherosclerotic (NA), fatty and fibrous-fatty atherosclerotic plaques (A) and calcified (C) arteries exhibited different spectral signatures related to different morphological structures presented in each tissue type. Discriminant analysis based on Mahalanobis distance was employed to classify the tissue type with respect to the relative intensity of each compound. This model was subsequently tested prospectively in a set of 55 spectra. The simplified diagnostic model showed that cholesterol, collagen, and adipocytes were the tissue constituents that gave the best classification capability and that those changes were correlated to histopathology. The simplified model, using spectra obtained from a few tissue morphological and biochemical constituents, showed feasibility by using a small amount of variables, easily extracted from gross samples.
Resumo:
Spinal cord injury (SCI) causes motor and sensory deficits that impair functional performance, and significantly impacts life expectancy and quality. Animal models provide a good opportunity to test therapeutic strategies in vivo. C57BL/6 mice were subjected to laminectomy at T9 and compression with a vascular clip (30 g force, 1 min). Two groups were analyzed: injured group (SCI, n = 33) and laminectomy only (Sham, n = 15). Locomotor behavior (Basso mouse scale-BMS and global mobility) was assessed weekly. Morphological analyses were performed by LM and EM. The Sham group did not show any morphofunctional alteration. All SCI animals showed flaccid paralysis 24 h after injury. with subsequent improvement. The BMS score of the SCI group improved until the intermediate phase (2.037 +/- 1.198): the Sham animals maintained the highest BMS score (8.981 +/- 0.056). p < 0.001 during the entire time. The locomotor speed was slower in the SCI animals (5.581 +/- 0.871) than in the Sham animals (15.80 +/- 1.166), p < 0.001. Morphological analysis of the SCI group showed, in the acute phase, edema, hemorrhage, multiple cavities, fiber degeneration, cell death and demyelination. In the chronic phase we observed glial scarring, neuron death, and remyelination of spared axons by oligodendrocytes and Schwann cells. In conclusion, we established a simple, reliable, and inexpensive clip compression model in mice, with functional and morphological reproducibility and good validity. The availability of producing reliable injuries with appropriate outcome measures represents great potential for studies involving cellular mechanisms of primary injury and repair after traumatic SCI. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
The use of biochemical and genetic characters to explore species or population relationships has been applied to taxonomic questions since the 60s. In responding to the central question of the evolutionary history of Triatominae, i.e. their monophyletic or polyphyletic origin, two important questions arise (i) to what extent is the morphologically-based classification valid for assessing phylogenetic relationships? and (ii) what are the main mechanisms underlying speciation in Triatominae? Phenetic and genetic studies so far developed suggest that speciation in Triatominae may be a rapid process mainly driven by ecological factors.
Resumo:
One of the main difficulties in studying dengue virus infection in humans and in developing a vaccine is the absence of a suitable animal model which develops the full spectrum of dengue fever, dengue haemorrhagic fever, and dengue shock syndrome. It is our proposal to present morphological aspects of an animal model which shows many similarities with the dengue infection in humans. BALB/c mice were intraperitoneally infected with non-neuroadapted dengue virus serotype 2 (DENV-2). Histopathological and morphometrical analyses of liver tissue revealed focal alterations along the infection, reaching wide-ranging portal and centrolobular veins congestion and sinusoidal cell death. Additional ultrastructural observations demonstrated multifocal endothelial injury, platelet recruitment, and alterated hepatocytes. Dengue virus antigen was detected in hepatocytes and in the capillar endothelium of the central lobular vein area. Liver function tests showed high levels of aspartate transaminase and alanine transaminase enzyme activity. Lung tissue showed interstitial pneumonia and mononuclear cells, interseptal oedema, hyperplasia, and hypertrophy of the bronchiolar epithelial cells. DENV-2 led to a transient inflammatory process, but caused focal alterations of the blood-exchange barrier. Viremia was observed from 2nd to 11th day p.i. by isolation of DENV-2 in C6/36 mosquito cell line inoculated with the supernatant of macerated liver, lung, kidney, and cerebellum tissues of the infected mice.
Resumo:
P>In this study, Bayesian analysis under a threshold animal model was used to estimate genetic correlations between morphological traits (body structure, finishing precocity and muscling) in Nelore cattle evaluated at weaning and yearling. Visual scores obtained from 7651 Nelore cattle at weaning and from 4155 animals at yearling, belonging to the Brazilian Nelore Program, were used. Genetic parameters for the morphological traits were estimated by two-trait Bayesian analysis under a threshold animal model. The genetic correlations between the morphological traits evaluated at two ages of the animal (weaning and yearling) were positive and high for body structure (0.91), finishing precocity (0.96) and muscling (0.94). These results indicate that the traits are mainly determined by the same set of genes of additive action and that direct selection at weaning will also result in genetic progress for the same traits at yearling. Thus, selection of the best genotypes during only one phase of life of the animal is suggested. However, genetic differences between morphological traits were better detected during the growth phase to yearling. Direct selection for body structure, finishing precocity and muscling at only one age, preferentially at yearling, is recommended as genetic differences between traits can be detected at this age.
Resumo:
In the present work we analyzed the effect of the chronic administration of risperidone (2mg/kg over 65 days) on behavioural, morphological and molecular aspects in an experimental model of schizophrenia obtained by bilateral injection of ibotenic acid into the ventral hippocampus of new-born rats. Our results show that during their adult lives the animals with hippocampal lesions exhibit different alterations, mainly at behavioural level and in the gene expression of dopamine D2 and 5-HT2A receptors. However, at morphological level the study performed on the prefrontal cortex did not reveal any alterations in either the thickness or the number of cells immunoreactive for c-Fos, GFAP, CBP or PV. Overall, risperidone administration elicited a trend towards the recovery of the values previously altered by the hippocampal lesion, approaching the values seen in the animals without lesions. It may be concluded that the administration of risperidone in the schizophrenia model employed helps to improve the altered functions, with no significant negative effects. © 2013.
Resumo:
This paper examines the daily morphological responses of Sununga Beach, an embayed beach located on the south-eastern Brazilian coast, to storms in the South Atlantic Ocean. The main mechanisms and timing of beach erosion and accretion, the relationship between wave height and direction, and beach volume changes are considered, to establish a qualitative model for short-term embayed beach morphological changes. The methodology consisted of daily topographic surveys during the month of May in 2001, 2002, and 2003, using an RTK-GPS (real-time kinematics global positioning system). Weather and wave model results were used to correlate hydrodynamics and beach morphology. The results indicate that the morphodynamics of Sununga Beach are characterized by a process of beach rotation, which occurred more or less clearly during all three surveys. Unlike what has been commonly described in the literature for longer time intervals and alternations of fair and stormy weather, the beach rotation processes on Sununga Beach occurred under conditions of moderate-to-high wave energy change (wave heights greater than 2 m). An integrated evaluation of the behaviour of the meteorological aspects, together with beach morphology, enabled us to recognize that extra-tropical cyclones were the most important agent in remobilizing the beach planform, whether in beach rotation or in cross-shore erosion. Copyright (C) 2010 John Wiley & Sons, Ltd.
Resumo:
Mathematical morphology has been an area of intensive research over the last few years. Although many remarkable advances have been achieved throughout these years, there is still a great interest in accelerating morphological operations in order for them to be implemented in real-time systems. In this work, we present a new model for computing mathematical morphology operations, the so-called morphological trajectory model (MTM), in which a morphological filter will be divided into a sequence of basic operations. Then, a trajectory-based morphological operation (such as dilation, and erosion) is defined as the set of points resulting from the ordered application of the instant basic operations. The MTM approach allows working with different structuring elements, such as disks, and from the experiments, it can be extracted that our method is independent of the structuring element size and can be easily applied to industrial systems and high-resolution images.
Resumo:
Obesity is associated with insulin resistance and is known to be a risk factor for type-2 diabetes. In obese individuals, pancreatic beta-cells try to compensate for the increased insulin demand in order to maintain euglycemia. Most studies have reported that this adaptation is due to morphological changes. However, the involvement of beta-cell functional adaptations in this process needs to be clarified. For this purpose, we evaluated different key steps in the glucose-stimulated insulin secretion (GSIS) in intact islets from female ob/ob obese mice and lean controls. Obese mice showed increased body weight, insulin resistance, hyperinsulinemia, glucose intolerance and fed hyperglycemia. Islets from ob/ob mice exhibited increased glucose-induced mitochondrial activity, reflected by enhanced NAD(P)H production and mitochondrial membrane potential hyperpolarization. Perforated patch-clamp examination of beta-cells within intact islets revealed several alterations in the electrical activity such as increased firing frequency and higher sensitivity to low glucose concentrations. A higher intracellular Ca(2+) mobilization in response to glucose was also found in ob/ob islets. Additionally, they displayed a change in the oscillatory pattern and Ca(2+) signals at low glucose levels. Capacitance experiments in intact islets revealed increased exocytosis in individual ob/ob beta-cells. All these up-regulated processes led to increased GSIS. In contrast, we found a lack of beta-cell Ca(2+) signal coupling, which could be a manifestation of early defects that lead to beta-cell malfunction in the progression to diabetes. These findings indicate that beta-cell functional adaptations are an important process in the compensatory response to obesity.
Resumo:
PURPOSE: Thermal injury causes catabolic processes as the body attempts to repair the damaged area. This study evaluated the effects of a scald injury on the morphology of muscle fibers belonging to a muscle distant from the lesion. METHODS: Thirty Wistar rats were divided into control (C) and scalded (S) groups. Group S was scalded over 45% of the body surface, standardized by body weight. Rats in both groups were euthanized at four, seven and 14 days following the injury. The middle portions of the medial gastrocnemius muscles were sectioned, stained with hematoxylin and eosin and Picrosirius, and submitted to histological analysis. RESULTS: Control group sections exhibited equidistantly distributed polygonal muscle fibers with peripheral nuclei, characteristic of normal muscle. The injured group sections did not consistently show these characteristics; many fibers in these sections exhibited a rounded contour, variable stain intensities, and greater interfiber distances. A substantially increased amount of connective tissue was also observed on the injured group sections. CONCLUSION: This experimental model found a morphological change in muscle distant from the site of thermal injury covering 45% of the body surface.