Fiber tracking

The major cognitive disturbances in schizophrenia may result from a deficit of myelination in relevant neuronal structures, such as the corpus callosum, involved in connectivity between both hemispheres the resulting decrease of electrical conduction in fiber tracks linking different parts of the brain may affect behavior and perception (Haroutunian and Davis, 2007 Haroutunian et al., 2007). 

Kinoshita M, Yamada K, Hashimoto N, Kato A, Izumoto S, Baba T, Maruno M, Nishimura T, Yoshimine T (2005) Fiber-tracking does not accurately estimate size of fiber bundle in pathological condition Initial neurosmgical experience using neuronavigation and subcortical white matter stimulation. Neuroimage 25 424-429. 

Fig. 9.7. Muscle fibers tracked in a high-resolution DTI MRI of a healthy mouse heart. Lighting and shadowing of lines combined with color coding of helix angle (aj,). From Peeters et al. (2006a)...

Since diffusion is fastest in the direction parallel to axons in a fiber bundle, diffusion measurements can be used to estimate fiber orientation in each voxel in an MRI data set. If these orientations are interpreted as the local tangent to fiber pathways, then the pathways can be reconstracted by following the fast diffusion direction from point to point along a fiber bundle [5-6]. Fiber tracking based on diffusion data, known as MR tractography, is used to visualize and segment specific anatomical fiber bundles in the brain (Figure 1). This kind of analysis makes it possible to characterize individual fiber bimdles and identify those that are affected by disease. 

Figure 29 (Qin and Liu, 1982) shows the behavior of individual particles above the distributor recorded by video camera of small clusters of particles, coated with a fluorescent material and spot-illuminated by a pulse of ultra violet light from an optical fiber. The sequential images, of which Fig. 29 just represents exposures after stated time intervals, were reconstructed to form the track of motion of the particle cluster shown in Fig. 30. Neither this track nor visual observation of the shallow bed while fluidized, reveal any vestige of bubbles. Instead, the particles are thrown up by the high velocity jets issuing from the distributor orifices to several times their static bed height.

Figure 46. Typical bed collapse curve traced by optical-fiber probe tracking instrument (solids alumina A66, 140-280 microns). (Yang, Tung, and Kwauk, 1985.)...

Selection of the material model is another important factor to be considered. Some programs allow the user to specify plastic moment-rotation curves for beam elements. However, the more rigorous and most widely available method of defining nonlinear material properties is to specify the stress versus strain data, Plastic behavior is approximated at the section level in the former method whereas, the latter method tracks plastic behavior at the individual integration points (fibers) through the thickness of the member. Each method has its advantages and disadvantages. 

The fiber industry has long been aware of PTT s good tensile elastic recovery [3], Ward et al. [4] studied the deformation behavior of PET, PTT and PBT fibers and found the tensile elastic recoveries were ranked in the unexpected descending order of PTT > PBT > PET. Chuah [47] found that the PTT elastic recovery and permanent set nearly tracked that of nylon 66 up to 30% strain (Figure 11.12). 

Using radioactive labeled UICC samples, the deposition and distribution of asbestiform fibers in the pulmonary cavity have been studied. For example, after thirty minutes of inhalation, the deposition of fibers in the respiratory track was shown to be proportional to the median aerodynamic particle diameter for the two UICC chrysotiles, amosite, anthophyllite, and crocidolite. The percentage of total deposited fiber in the lower respiratory tract varied inversely as the square root of the particle diameter (Morgan et al., 1975). 

As mentioned earlier, chemicals and explosives are usually detected spectroscopically. Fiber-optic-based chemical sensors have application in the real-time tracking of rapidly changing chemical environments. These sensors provide rapid... 

Pultrusion is a steady-state process in which the fiber-resin mass changes its properties as it moves from the entrance to the exit of the die. In order to track the temperature, polymer conversion, and other properties of the fiber-resin mass as it moves along the die, it is useful to define a representative volume element (RVE) that rides along the fiber at the line speed of the pultrusion process. An RVE is defined such that it will contain both the solid phase (i.e., fibers and resin), irrespective of its location in the composite. In real-life pultrusion, a thermocouple wire that passes through the pultrusion die tracks the temperature of an RVE in the composite. 

Poor impregnation will result if the fiber volume fraction is so low that a region without fibers is formed on top of the reinforcement. This can happen, for example, if high performance fabrics with a high uncompacted fiber volume fraction are used at a too-low-fiber volume fraction. This situation is similar to the race tracking problem described earlier. Flow on top of the reinforcement can occur, even if the whole cavity thickness is filled with fibers, if... 

Fig. li. The change in failure at the single-fiber level as shown by the embedded single-fiber test is mirrored by the failure behavior at the macroscopic level. The increase in adhesion also tracks the same between the ITS results and 0° flexure data. 

I realize that this is a side track issue, but relevant all the same. Cycle protocols were an approach intended to facilitate optimal growth of muscle tissue. Remember there are two main muscle fiber types Type I, which is endurance orientated, and Type II which is strength orientated. Type "Ha", "Hb", and Type "He" are responsible for most musculature size and have the greatest potential for growth. Testosterone increases the number of Type II fibers at the expense of the Type I transformation. Growth hormone, Insulin, IGF-1, and thyroid hormones effect growth and hyperplasia of both fiber types. This should be another key relating to protocols that were utilized and why. 

When microtubules were visualized by electron microscopy (EM), after the improvement of methods of fixation, it was realized that they formed the structural basis of flagellar axonemes and of so-called spindle fibers, as well as occurring as individual filaments in the cytoplasm. Their designation as part of the cytoskeleton suggested that they acted mainly as fixed structural supports. Subsequent research has focused more and more on their dynamic behavior and on their role as tracks for motor proteins, which may, for example, transport chromosomes during cell division. Microtubules are found in all eukaryotic cells and are essential for many cellular functions, such as motility, morphogenesis, intracellular transport, and cell division. It is that dynamic behavior that allows microtubules to fulfill all of these functions in specific places and at appropriate times in the cell cycle. 

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