Gamma-ray bursts are believed to be produced when fast moving ejecta from some central source collides with slower moving, but relativistic, shells that were ejected at an earlier time. In this so called internal shock scenario we expect some fraction of the energy of the burst to be carried by slow moving shells that were ejected at late times. These slow shells collide with faster moving oute...

We present the results of UBV JHKLM photometry of RCrB spanning the period from 1976 to 2001. Studies of the optical light curve have shown no evidence of any stable harmonics in the variations of the stellar emission. In the L band we found semi-regular oscillations with the two main periods of ∼ 3.3 yr and ∼ 11.9 yr and the full amplitude of ∼ 0. 8 and ∼ 0. 6, respectively. The colors of the ...

A shell like structure is sought as a solution of a free boundary problem derived from the Ohta-Kawasaki theory of diblock copolymers. The boundary of the shell satisfies an equation that involves its mean curvature and the location of the entire shell. A variant of Lyapunov-Schmidt reduction process is performed that rigorously reduces the free boundary problem to a finite dimensional problem....

Unimolecular core−shell and hollow polymer nanoparticles with well-defined dimensions were crafted using spherical core−shell starlike diblock copolymers as templates. Monodisperse and structurally stable star-like diblock copolymers composed of inner degradable core blocks and outer photo-cross-linkable shell blocks were synthesized via a combination of two living polymerization techniques, na...

A popular paradigm to explain the rapid temporal variability observed in gamma-ray burst (GRB) light curves is the internal shock model. We propose an alternative model in which the radiating fluid in the GRB shell is relativistically turbulent with a typical eddy Lorentz factor γ t. In this model, all pulses in the gamma-ray light curve are produced at roughly the same distance R from the cent...

The elastic-plastic deformation, limiting states and supercritical behavior of cylindrical shells under tension combined loading by internal pressure to failure are studied theoretically experimentally. This problem is characterized the occurrence large strains, shape changes and, as a result, an inhomogeneous stress-strain state. In numerical solution such problems, arises constructing true cu...

conclusions although in our study washout pattern was the most powerful indicator for malignant pathology in non mass like enhancing lesions, more studies with larger sample size needs in this regard. background several studies on the diagnostic efficacy of mri has not real consensus for the accuracy of mri characteristics in non mass like breast lesions, and the number of malignant lesions in ...

The present work reports on the preparation of core–shell-like zeolites with a Si-rich mesoporous shell.

Glutamatergic system stimulationthe nucleus accumbens shell, may affect anxiety-related behaviors, aversive learning and memory. Glutamate receptors are differentially distributed in preand postsynaptic sites contributing to neuronal communications.The present study aimed to examine the possible involvement of the NAc shell presynaptic NMDA receptors on NMDA induced responses, using the elevate...

One might at first tend to think that the growth of plants and animals, because of their elaborate forms, are ruled by highly complex laws. However, this is surprisingly not always true: many aspects of the growth of plants and animals may be described by remarkably simple mathematical laws. An obvious example of this are the seashells and snails, as we show here: with a very simple model it is...