Viscoelastic State for the Solutions of Spherically Symmetric Viscoelasticity Problems

The solutions of the spherically symmetric, linear, isothermal, and transient viscoelasticity problems via reciprocity theorem have been investigated for a specific material. The integral form of stress–strain relations has been used. The Laplace transform of a viscoelastic state, which is necessary for the integral equation arising as a result of reciprocity theorem, has been derived. This integral equation has been solved by Laplace transform. A sample problem has been solved to test the presented formulation. A numerical application of the analytic solution of this problem has been given.     

Mutations in filamin 1 prevent migration of cerebral cortical neurons in human periventricular heterotopia

Long-range, directed migration is particularly dramatic in the cerebral cortex, where postmitotic neurons generated deep in the brain migrate to form layers with distinct form and function. In the X-linked dominant human disorder periventricular heterotopia (PH), many neurons fail to migrate and persist as nodules lining the ventricular surface. Females with PH present with epilepsy and other signs, including patent ductus arteriosus and coagulopathy, while hemizygous males die embryonically. We have identified the PH gene as filamin 1 (FLN1), which encodes an actin-cross-linking phosphoprotein that transduces ligand-receptor binding into actin reorganization, and which is required for locomotion of many cell types. FLN1 shows previously unrecognized, high-level expression in the developing cortex, is required for neuronal migration to the cortex, and is essential for embryogenesis.     

Analysis of PVC Pipe-Wall Viscoelasticity during Water Hammer

This research work focuses on the analysis of hydraulic transients in polyvinyl chloride (PVC) pipes, which are characterized by a viscoelastic rheological behavior. Transient pressure data were collected in a pipe rig consisting of a set of PVC pipes. The creep function of the PVC pipes was determined by using an inverse transient model based on collected transient pressure data and compared with that obtained by carrying out mechanical tensile tests of PVC pipe specimens. The numerical results obtained from the transient solver have shown that the attenuation, dispersion, and shape of transient pressures were well described. The incorporation of the viscoelastic mechanical behavior in the hydraulic transient model has provided an excellent fitting between numerical results and observed data. Calibrated creep function based on inverse analysis fit the one determined by mechanical tests well, which emphasized the importance of pipe-wall viscoelasticity in hydraulic transients in PVC pipes.     

Purification and properties of filamin, and actin binding protein from chicken gizzard

Filamin, a protein recently identified in chicken gizzard (Wang, K., Ash, F., and Singer, S. J. (1975) Proc. Natl. Acad. Sci. U. S. A. 72, 4483-4486), has been purified free of other components and its molecular properties have been examined. Filamin has a sedimentation constant (S020,w) of 8.86 S and a partial specific volume of 0.734 ml/g. Sedimentation equilibrium experiments give a value of 498,000 for the molecular weight of native filamin. From these data a frictional ratio of 2.32 has been calculated. On sodium dodecyl sulfate gel electrophoresis, filamin migrates as a single protein band with an estimated molecular weight of 240,000. Filamin is a soluble protein and under a variety of conditions tested does not by itself form filaments or precipitate from solution. However, filamin binds to rabbit skeletal muscle F-actin, and the complex is readily sedimented by centrifugation to yield a gelatinous pellet containing actin and filamin. These results indicate that filamin is a dimeric protein with a moderate degree of asymmetry that binds to actin. The results also suggest that the distribution of filamin in cells is derived from its interaction with polymerized actin.     

Oxygen parameters in the presence of hemoglobin H

Two cases of an unusual finding of capsular pseudoinvasion in follicular thyroid adenomas after fine-needle aspiration (FNA) procedures are reported. These capsular breaches were noted along the hemorrhagic needle track, which traversed the normal peripheral thyroid parenchyma into the lesions. A reparative reaction was seen at some points along one of the tracks. Histologic examination also showed extrusion of the tumor parenchyma through the capsular interruption in one case. Surgical pathologists should be aware of this rare complication of FNA of thyroid follicular adenomas as a differential diagnosis of minimally invasive (encapsulated) follicular carcinoma.