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Image Analysis Techniques (image + analysis_techniques)
Selected AbstractsNet changes in regional woody vegetation cover and carbon storage in Texas Drylands, 1937,1999GLOBAL CHANGE BIOLOGY, Issue 3 2003GREGORY P. ASNER Abstract Although local increases in woody plant cover have been documented in arid and semiarid ecosystems worldwide, there have been few long-term, large-scale analyses of changes in woody plant cover and aboveground carbon (C) stocks. We used historical aerial photography, contemporary Landsat satellite data, field observations, and image analysis techniques to assess spatially specific changes in woody vegetation cover and aboveground C stocks between 1937 and 1999 in a 400-km2 region of northern Texas, USA. Changes in land cover were then related to topo-edaphic setting and historical land-use practices. Mechanical or chemical brush management occurred over much of the region in the 1940,1950s. Rangelands not targeted for brush management experienced woody cover increases of up to 500% in 63 years. Areas managed with herbicides, mechanical treatments or fire exhibited a wide range of woody cover changes relative to 1937 (,75% to + 280%), depending on soil type and time since last management action. At the integrated regional scale, there was a net 30% increase in woody plant cover over the 63-year period. Regional increases were greatest in riparian corridors (33%) and shallow clay uplands (26%) and least on upland clay loams (15%). Allometric relationships between canopy cover and aboveground biomass were used to estimate net aboveground C storage changes in upland (nonriparian) portions of regional landscapes. Carbon stocks increased from 380 g C m,2 in 1937 to 500 g C m,2 in 1999, a 32% net increase across the 400 km2 region over the 63-year period. These plant C storage change estimates are highly conservative in that they did not include the substantial increases in woody plant cover observed within riparian landscape elements. Results are discussed in terms of implications for ,carbon accounting' and the global C cycle. [source] Use of image analysis techniques for objective quantification of the efficacy of different hair removal methodsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2007S. Bielfeldt In the field of consumer-used cosmetics for hair removal and hair growth reduction, there is a need for improved quantitative methods to enable the evaluation of efficacy and claim support. Optimized study designs and investigated endpoints are lacking to compare the efficacy of standard methods, like shaving or plucking, with new methods and products, such as depilating instruments or hair-growth-reducing cosmetics. Non-invasive image analysis, using a high-performance microscope combined with an optimized image analysis tool, was investigated to assess hair growth. In one step, high-resolution macrophotographs of the legs of female volunteers after shaving and plucking with cold wax were compared to observe short-term hair regrowth. In a second step, images obtained after plucking with cold wax were taken over a long-term period to assess the time, after which depilated hairs reappeared on the skin surface. Using image analysis, parameters like hair length, hair width, and hair projection area were investigated. The projection area was found to be the parameter most independent of possible image artifacts such as irregularities in skin or low contrast due to hair color. Therefore, the hair projection area was the most appropriate parameter to determine the time of hair regrowth. This point of time is suitable to assess the efficacy of different hair removal methods or hair growth reduction treatments by comparing the endpoint after use of the hair removal method to be investigated to the endpoint after simple shaving. The closeness of hair removal and visible signs of skin irritation can be assessed as additional quantitative parameters from the same images. Discomfort and pain rating by the volunteers complete the set of parameters, which are required to benchmark a new hair removal method or hair-growth-reduction treatment. Image analysis combined with high-resolution imaging techniques is a powerful tool to objectively assess parameters like hair length, hair width, and projection area. To achieve reliable data and to reduce well known image-analysis artifacts, it was important to optimize the technical equipment for use on human skin and to improve image analysis by adaptation of the image-processing procedure to the different skin characteristics of individuals, like skin color, hair color, and skin structure. [source] Quantification of dynamic mixing performance of single screws of different configurations by visualization and image analysisADVANCES IN POLYMER TECHNOLOGY, Issue 1 2009A. C.-Y. Abstract The visualization and image analysis techniques developed by the authors for the study of quantifying the dynamic quality of mixing of a single-screw extruder were employed to investigate the mixing performance of screws of different configurations. The mixing quality was quantified by calculating the variances of the light intensity of the bitmap files cropped from the films taken at the screw length of 15D and 17D of a 45-mm screw diameter single-screw extruder. Temperature and screw speed were the two variables studied. While temperature and back pressure were found to have little effect on the mixing quality, screw speed was demonstrated to be a major factor responsible for the mixing fluctuation observed during extrusion. In fact, screw speed and mixing fluctuation appeared to have a relationship that the higher the screw speed, the bigger the fluctuation (i.e., poorer quality of mixing). The experimental results also revealed that the secondary flight of a barrier screw might be essential to improve the quality of mixing. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:1,15, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20142 [source] Characterization of the Mucor circinelloides life cycle by on-line image analysisJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003T.L. Lübbehüsen Abstract Aims: The life cycle of the dimorphic fungus Mucor circinelloides was studied in a temperature-controlled flow-through cell, which constitutes an ideal tool when following the development of individual cells, with a view to understanding the growth and differentiation processes occurring in and between the different morphological forms of the organism. Methods and Results: Mycelial growth and the transformation of hyphae into chains of arthrospores were characterized by image analysis techniques and described quantitatively. The influence of the nature (glucose and xylose) and concentration of the carbon source on specific growth rate and hyphal growth unit length were studied. The organism branched more profusely on xylose than on glucose while the specific growth rates determined were rather similar. Methods were developed to study the yeast-like growth phase of M. circinelloides in the flow-through cell, and combined with fluorescent microscopy which allowed new insights to bud formation. Additionally, numbers and distribution of nuclei in arthrospores, hyphae and yeasts were studied. Conclusions: The results give essential information on the morphological development of the organism. Significance and Impact of Study: Development of any industrial process utilizing this organism will be dependent on the information obtained here for effective process optimization. [source] MRI tissue characterization of experimental cerebral ischemia in ratJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2003Hamid Soltanian-Zadeh PhD Abstract Purpose To extend the ISODATA image segmentation method to characterize tissue damage in stroke, by generating an MRI score for each tissue that corresponds to its histological damage. Materials and Methods After preprocessing and segmentation (using ISODATA clustering), the proposed method scores tissue regions between 1 and 100. Score 1 is assigned to normal brain matter (white or gray matter), and score 100 to cerebrospinal fluid (CSF). Lesion zones are assigned a score based on their relative levels of similarities to normal brain matter and CSF. To evaluate the method, 15 rats were imaged by a 7T MRI system at one of three time points (acute, subacute, chronic) after MCA occlusion. Then they were killed and their brains were sliced and prepared for histological studies. MRI of two or three slices of each rat brain (using two DWI (b = 400, b = 800), one PDWI, one T2WI, and one T1WI) was performed, and an MRI score between 1 and 100 was determined for each region. Segmented regions were mapped onto the histology images and scored on a scale of 1,10 by an experienced pathologist. The MRI scores were validated by comparison with histology scores. To this end, correlation coefficients between the two scores (MRI and histology) were determined. Results Experimental results showed excellent correlations between MRI and histology scores at different time points. Depending on the reference tissue (gray matter or white matter) used in the standardization, the correlation coefficients ranged from 0.73 (P < 0.0001) to 0.78 (P < 0.0001) using the entire dataset, including acute, subacute, and chronic time points. This suggests that the proposed multiparametric approach accurately identified and characterized ischemic tissue in a rat model of cerebral ischemia at different stages of stroke evolution. Conclusion The proposed approach scores tissue regions and characterizes them using unsupervised clustering and multiparametric image analysis techniques. The method can be used for a variety of applications in the field of computer-aided diagnosis and treatment, including evaluation of response to treatment. For example, volume changes for different zones of the lesion over time (e.g., tissue recovery) can be evaluated. J. Magn. Reson. Imaging 2003;17:398,409. © 2003 Wiley-Liss, Inc. [source] Comparative morphology of stingray lateral line canal and electrosensory systemsJOURNAL OF MORPHOLOGY, Issue 11 2008Laura K. JordanArticle first published online: 24 JUL 200 Abstract Elasmobranchs (sharks, skates, and rays) possess a variety of sensory systems including the mechanosensory lateral line and electrosensory systems, which are particularly complex with high levels of interspecific variation in batoids (skates and rays). Rays have dorsoventrally compressed, laterally expanded bodies that prevent them from seeing their mouths and more often than not, their prey. This study uses quantitative image analysis techniques to identify, quantify, and compare structural differences that may have functional consequences in the detection capabilities of three Eastern Pacific stingray species. The benthic round stingray, Urobatis halleri, pelagic stingray, Pteroplatytrygon (Dasyatis) violacea, and benthopelagic bat ray, Myliobatis californica, show significant differences in sensory morphology. Ventral lateral line canals correlate with feeding ecology and differ primarily in the proportion of pored and nonpored canals and the degree of branching complexity. Urobatis halleri shows a high proportion of nonpored canals, while P. violacea has an intermediate proportion of pored and nonpored canals with almost no secondary branching of pored canals. In contrast, M. californica has extensive and highly branched pored ventral lateral line canals that extended laterally toward the wing tips on the anterior edge of the pectoral fins. Electrosensory morphology correlates with feeding habitat and prey mobility; benthic feeders U. halleri and M. californica, have greater electrosensory pore numbers and densities than P. violacea. The percentage of the wing surface covered by these sensory systems appears to be inversely related to swimming style. These methods can be applied to a broader range of species to enable further discussion of the relationship of phylogeny, ecology, and morphology, while the results provide testable predictions of detection capabilities. J. Morphol., 2008. © 2008 Wiley-Liss, Inc. [source] Investigation of impinging-jet crystallization with a calcium oxalate model systemAICHE JOURNAL, Issue 9 2003Jean M. Hacherl An impinging-jet crystallizer was investigated in this work to assess its operational sensitivity and reproducibility for the production of small, monodisperse crystals using calcium oxalate, a model system capable of forming multiple hydrates. The impinging-jet mixer provides rapid mixing of the reactant solutions through the impingement of two narrow reactant streams at high velocity. Impinging jet linear velocity and postjetting conditions were studied, with the jet operated in nonsubmerged mode. Hydrate form and crystal-size distribution (CSD) were determined using optical microscopy and image analysis techniques. The impinging jet consistently produced small, monodisperse crystals. However, at a high level of supersaturation, slight variations in the CSD were observed for apparently identical conditions, suggesting a degree of sensitivity in the system that could lead to difficulty in its application. An apparent trend between impinging-jet linear velocity and crystal size and number was observed, with more small crystals produced at higher linear velocity. [source] An autonomous phase-boundary detection technique for colloidal hard sphere suspension experiments,MICROSCOPY RESEARCH AND TECHNIQUE, Issue 4 2006Mark McDowell Abstract Colloidal suspensions of monodisperse spheres are used as physical models of thermodynamic phase transitions and as precursors to photonic band gap materials. Current techniques for identifying the phase boundaries involve manually identifying the phase transitions, which is very tedious and time-consuming. In addition, current image analysis techniques are not able to distinguish between densely packed phases within conventional microscope images, which are mainly characterized by degrees of randomness or order with similar grayscale value properties. We have developed an intelligent machine vision technique that automatically identifies colloidal phase boundaries. The technique utilizes intelligent image processing algorithms that accurately identify and track phase changes vertically or horizontally for a sequence of colloidal hard sphere suspension images. This technique is readily adaptable to any imaging application wherein regions of interest are distinguished from the background by differing patterns of motion over time. Microsc. Res. Tech. 69:236,245, 2006. Published 2006 Wiley-Liss, Inc. [source] SPECT and Alzheimer's DiseasePSYCHOGERIATRICS, Issue 2 2002Siobhan Ni Bhriain Abstract: This article is review of the role of single photon emission tomography (SPECT) in the diagnosis and management of Alzheimer's disease (AD). It begins by describing AD in terms of diagnosis, pathology and current pharmacological treatment. The relevance of the pathological changes in relation to SPECT is outlined. This is discussed in terms of receptor abnormalities and atrophic changes which in turn effect cerebral blood flow. A detailed description of SPECT methodology describes how the quality of the image is effected by SPECT instrumentation, image reconstruction techniques and a number of subject factors. The article goes on to discuss the role SPECT in the diagnosis of AD and its potential for facilitating early diagnosis. The main focus here is on the changes which occur in cerebral blood flow in AD and the sensitivity and specificity of regional changes in cerebral blood flow is described. Image analysis is an area in which there has been many developments in the last number of years and the authors describe the differences between qualitative and quantitative image analysis, with a particular focus on statistical parametric mapping (SPM). There is a brief discussion concerning receptor ligands and their potential use in the diagnosis and management of AD, although this remains an undeveloped area in SPECT imaging as yet. Finally, the authors discuss the future possibilities for SPECT and AD, and conclude that there is considerable potential for SPECT in the diagnosis and management of AD with further refinement of image analysis techniques and the development of cholinergic receptor ligands. [source] Population estimation of human embryonic stem cell culturesBIOTECHNOLOGY PROGRESS, Issue 2 2010Thomas Thurnherr Abstract Traditionally, the population of human embryonic stem cell (hESC) culture is estimated through haemacytometer counts, which include harvesting the cells and manually analyzing a fraction of an entire population. Obviously, through this highly invasive method, it is not possible to preserve any spatial information on the cell population. The goal of this study is to identify a fast and consistent method for in situ automated hESC population estimation to quantitatively estimate the cell growth. Therefore, cell cultures were fixed, stained, and their nuclei imaged through high-resolution microscopy, and the images were processed with different image analysis techniques. The proposed method first identifies signal and background by computing an image specific threshold for image segmentation. By applying a morphological operator (watershed), we split most physically overlapping nuclei, leading to a pixel area distribution of isolated signal areas on the image. On the basis of this distribution, we derive a nucleus area model, describing the distribution of the area of cell debris, single nuclei, and small groups of connected nuclei. Through the model, we can give a quantitative estimation of the population. The focus of this study is on low-density human embryonic stem cell populations; hence cultures were measured at days 2,3 after seeding. Compared with manual cell counts, the automatic method achieved higher accuracy with <6% error. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] | ||||||||||||||||