Are There Topological Black Hole Solitons in String Theory?

We point out that the celebrated Hawking effect of quantum instability of black holes seems to be related to a nonperturbative effect in string theory. Studying quantum dynamics of strings in the gravitational background of black holes we find classical instability due to emission of massless string excitations. The topology of a black hole seems to play a fundamental role in developing the string theory classical instability due to the effect of sigma model instantons. We argue that string theory allows for a qualitative description of black holes with very small masses and it predicts topological solitons with quantized spectrum of masses. These solitons would not decay into string massless excitations but could be pair created and may annihilate also. Semiclassical mass quantization of topological solitons in string theory is based on the argument showing existence of nontrivial zeros of beta function of the renormalization group.Comment: 12 pages, TeX, requires phyzzx.tex, published in Gen. Rel. Grav. 19 (1987) 1173; comment added on December 18, 199

NN Interaction JISP16: Current Status and Prospect

We discuss realistic nonlocal NN interactions of a new type - J-matrix Inverse Scattering Potential (JISP). In an ab exitu approach, these interactions are fitted to not only two-nucleon data (NN scattering data and deuteron properties) but also to the properties of light nuclei without referring to three-nucleon forces. We discuss recent progress with the ab initio No-core Shell Model (NCSM) approach and respective progress in developing ab exitu JISP-type NN-interactions together with plans of their forthcoming improvements.Comment: 9 pages, 3 figures, to be published in Proceedings of Few-body 19 conferenc

3D global simulations of a cosmic-ray-driven dynamo in dwarf galaxies

Star-forming dwarf galaxies can be seen as the local proxies of the high-redshift building blocks of more massive galaxies according to the current paradigm of the hierarchical galaxy formation. They are low-mass objects, and therefore their rotation speed is very low. Several galaxies are observed to show quite strong magnetic fields. These cases of strong ordered magnetic fields seem to correlate with a high, but not extremely high, star formation rate. We investigate whether these magnetic fields could be generated by the cosmic-ray-driven dynamo. The environment of a dwarf galaxy is unfavourable for the large-scale dynamo action because of the very slow rotation that is required to create the regular component of the magnetic field. We built a 3D global model of a dwarf galaxy that consists of two gravitational components: the stars and the dark-matter halo described by the purely phenomenological profile proposed previously. We solved a system of magnetohydrodynamic (MHD) equations that include an additional cosmic-ray component described by the fluid approximation. We found that the cosmic-ray-driven dynamo can amplify the magnetic field with an exponential growth rate. The $e$-folding time is correlated with the initial rotation speed. The final mean value of the azimuthal flux for our models is of the order of few $\mu$G and the system reaches its equipartition level. The results indicate that the cosmic-ray-driven dynamo is a process that can explain the magnetic fields in dwarf galaxies.Comment: 6 pages, 4 figures, accepted for publication in A&

Cosmic-ray driven dynamo in the interstellar medium of irregular galaxies

Irregular galaxies are usually smaller and less massive than their spiral, S0, and elliptical counterparts. Radio observations indicate that a magnetic field is present in irregular galaxies whose value is similar to that in spiral galaxies. However, the conditions in the interstellar medium of an irregular galaxy are unfavorable for amplification of the magnetic field because of the slow rotation and low shearing rate. We investigate the cosmic-ray driven dynamo in the interstellar medium of an irregular galaxy. We study its efficiency under the conditions of slow rotation and weak shear. The star formation is also taken into account in our model and is parametrized by the frequency of explosions and modulations of activity. The numerical model includes a magnetohydrodynamical dynamo driven by cosmic rays that is injected into the interstellar medium by randomly exploding supernovae. In the model, we also include essential elements such as vertical gravity of the disk, differential rotation approximated by the shearing box, and resistivity leading to magnetic reconnection. We find that even slow galactic rotation with a low shearing rate amplifies the magnetic field, and that rapid rotation with a low value of the shear enhances the efficiency of the dynamo. Our simulations have shown that a high amount of magnetic energy leaves the simulation box becoming an efficient source of intergalactic magnetic fields.Comment: 9 pages, 6 figure

Prospects for the Application of Nanotechnologies to the Computer System Architecture

Computer system architecture essentially influences the comfort of our everyday living. Developmental transition from electromechanical relays to vacuum tubes, from transistors to integrated circuits has significantly changed technological standards for the architecture of computer systems. Contemporary information technologies offer huge potential concerning miniaturization of electronic circuits. Presently, a modern integrated circuit includes over a billion of transistors, each of them smaller than 100 nm . Stepping beyond the symbolic 100 nm limit means that with the onset of the 21 century we have entered a new scientific area that is an era of nanotechnologies. Along with the reduction of transistor dimensions their operation speed and efficiency grow. However, the hitherto observed developmental path of classical electronics with its focus on the miniaturization of transistors and memory cells seems arriving at the limits of technological possibilities because of technical problems as well as physical limitations related to the appearance of new nano-scale phenomena as e.g. quantum effects. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2488

Prospects for the Application of Nanotechnologies to the Computer System Architecture

Computer system architecture essentially influences the comfort of our everyday living. Developmental transition from electromechanical relays to vacuum tubes, from transistors to integrated circuits has significantly changed technological standards for the architecture of computer systems. Contemporary information technologies offer huge potential concerning miniaturization of electronic circuits. Presently, a modern integrated circuit includes over a billion of transistors, each of them smaller than 100 nm . Stepping beyond the symbolic 100 nm limit means that with the onset of the 21 century we have entered a new scientific area that is an era of nanotechnologies. Along with the reduction of transistor dimensions their operation speed and efficiency grow. However, the hitherto observed developmental path of classical electronics with its focus on the miniaturization of transistors and memory cells seems arriving at the limits of technological possibilities because of technical problems as well as physical limitations related to the appearance of new nano-scale phenomena as e.g. quantum effects. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2488