Intermediate-scale spurs are common in spiral galaxies, but perhaps most distinctively evident in a recent image showing a quasi-regular series of dust lanes projecting from the arms of M51 (Scoville & Rector 2001). We investigate, using time-dependent numerical MHD simulations, how such spurs could form (and subsequently fragment) from the interaction of a gaseous interstellar medium with a st...

Flow nonnormality induced linear transient phenomena in thin self-gravitating astrophysical discs are studied in the shearing sheet approximation. The considered system includes two modes of perturbations: vortex and (spiral density) wave. It is shown that self-gravity considerably alters the vortex mode dynamics – its transient (swing) growth may be several orders of magnitude stronger than in...

Grain selection is an important process in single crystal turbine blades manufacturing. Selector structure is a control factor of grain selection, as well as directional solidification (DS). In this study, the grain selection and structure design of the spiral selector were investigated through experimentation and simulation. A heat transfer model and a 3D microstructure growth model were estab...

background: x-ray computed tomography (ct) examinations deliver a significant amount of radiation doses to patients comparing to conventional radiography examinations. the objective of the current study was to analyze and investigate the average patient received dose from axial and spiral ct exams in a medical imaging center. material and methods: in this study, the patient imaging technique, w...

Background: During the first trimester of pregnancy the uterine spiral arteries that supply blood to the placenta are remodelled, creating heavily dilated conduits lacking maternal vasomotor control. To effect permanent vasodilatation, the internal elastic lamina and medial elastic fibres must be degraded. Failure of remodelling is a key characteristic of the pathological placenta and is though...

This paper attempts to unify a variety of dynamic hashing methods. Spiral storage, linear hashing and to a certain extent, linear hashing with partial expansions can be seen as particular cases of a more general technique. The approach is closest to spiral storage in concept. A new instantiation of the general method is offered which permits an adjustment to the dynamic growth rate during expan...

Mirrored carbon-spirals have been produced from pressured ferrocene via the bilateral extrusion of the spiral pairs from an iron core. A parametric plot of the surface geometry displays the fractal growth of the conical helix made with the logarithmic spiral. Electron microscopy studies show the core is a crystalline cementite which grows and transforms its shape from spherical to biconical as ...

Using recently proposed improvements of reflection electron microsopy (REM) we study, in perfectly controlled thermodynamics conditions, spiral and spirals shapes on Si(111) surface. It is shown that the new method named low distortion reflection electron microscopy (LODREM) is a powerful instrument, resolving in much more details (compared with REM) growth or evaporation spirals at the crystal...

conclusions the automatic bolus-tracking method, results in higher contrast enhancement of the aorta and spleen at the portal phase, but has no effect on liver enhancement. however, bolus tracking is associated with reduced variability for liver enhancement among different patients. results forty-eight patients (23 male, 25 female, mean age=56.4±13.5 years) were included. the contrast enhanceme...