Bistability and instability of dark-antidark solitons in the cubic-quintic nonlinear Schroedinger equation

We characterize the full family of soliton solutions sitting over a background plane wave and ruled by the cubic-quintic nonlinear Schroedinger equation in the regime where a quintic focusing term represents a saturation of the cubic defocusing nonlinearity. We discuss existence and properties of solitons in terms of catastrophe theory and fully characterize bistability and instabilities of the dark-antidark pairs, revealing new mechanisms of decay of antidark solitons.Comment: 8 pages, 10 figures, accepted in PR

Connections of the Mesencephalic Locomotor Region (MLR) in the Cat

The cat entopeduncular nucleus (EN), which is the main output of the basal ganglia, is known to project to the mesencephalic tegmentum. We have been able to elicit antidromic responses in single EN neurons from the region of the mesencephalic locomotor region (MLR), then transect (precollicular-postmamillary) the brainstem and elicit rhythmic movements of the limbs by stimulation of the same site in the same animal. Injections of the fluorescent dye 2,4 diamidino phenylindole 2 HCL (DAPI) into this area induces retrograde labeling of cell bodies in EN and motor cortex. Injections of a tritiated amino acid (leucine) into the motor cortex induce terminal labeling in the area of the MLR. These studies describe convergent projections from EN and motor cortex to the MLR. These connections may be involved in the sequencing and ordering of voluntary movements in which locomotion is necessary

Generalized coherent states are unique Bell states of quantum systems with Lie group symmetries

We consider quantum systems, whose dynamical symmetry groups are semisimple Lie groups, which can be split or decay into two subsystems of the same symmetry. We prove that the only states of such a system that factorize upon splitting are the generalized coherent states. Since Bell's inequality is never violated by the direct product state, when the system prepared in the generalized coherent state is split, no quantum correlations are created. Therefore, the generalized coherent states are the unique Bell states, i.e., the pure quantum states preserving the fundamental classical property of satisfying Bell's inequality upon splitting.Comment: 4 pages, REVTeX, amssymb style. More information on http://www.technion.ac.il/~brif/science.htm

The Tobacco Epidemic in South-East Europe: Consequences and Policy Responses. Health, Nutrition and Population Discussion Paper

Smoking is the single largest cause of premature mortality in the developed world. Obtaining accurate estimates of smoking's impacts in south east Europe (SEE) is hindered by the lack of accurate data.. None of the countries of the region yet conduct regular national surveys of adult smoking prevalence and some have no recent nationally representative data available. The very high rates among medical personnel are cause for concern. Youth smoking surveys are now conducted in most countries as part of international projects and show rates broadly similar to the EU. The collapse of communism and the end of the conflicts in the 1990s has led to major changes in the region's tobacco industry. The previously state-owned tobacco monopolies have either undergone or are undergoing privatization and the transnational tobacco companies have been increasingly active both in importing their cigarettes to, and investing in, the region. These changes can be expected to increase competition in the tobacco industry which will in turn drive down prices and increase advertising, thereby stimulating consumption. The available statistics, combined with the changes to the region's tobacco industry, suggest that the health impacts of tobacco in SEE will continue to worsen over coming years

Constraining the Distribution of L- & T-Dwarfs in the Galaxy

We estimate the thin disk scale height of the Galactic population of L- & T-dwarfs based on star counts from 15 deep parallel fields from the Hubble Space Telescope. From these observations, we have identified 28 candidate L- & T- dwarfs based on their (i'-z') color and morphology. By comparing these star counts to a simple Galactic model, we estimate the scale height to be 350+-50 pc that is consistent with the increase in vertical scale with decreasing stellar mass and is independent of reddening, color-magnitude limits, and other Galactic parameters. With this refined measure, we predict that less than 10^9 M_{sol} of the Milky Way can be in the form L- & T- dwarfs, and confirm that high-latitude, z~6 galaxy surveys which use the i'-band dropout technique are 97-100% free of L- & T- dwarf interlopers.Comment: 4 pages, 4 figures, accepted to ApJ

Diffuse Extragalactic Background Radiation

Attenuation of high--energy gamma rays by pair--production with UV, optical and IR background photons provides a link between the history of galaxy formation and high--energy astrophysics. We present results from our latest semi-analytic models (SAMs), based upon a $\Lambda$CDM hierarchical structural formation scenario and employing all ingredients thought to be important to galaxy formation and evolution, as well as reprocessing of starlight by dust to mid- and far-IR wavelengths. Our models also use results from recent hydrodynamic galaxy merger simulations. These latest SAMs are successful in reproducing a large variety of observational constraints such as number counts, luminosity and mass functions, and color bimodality. We have created 2 models that bracket the likely ranges of galaxy emissivities, and for each of these we show how the optical depth from pair--production is affected by redshift and gamma-ray energy. We conclude with a discussion of the implications of our work, and how the burgeoning science of gamma-ray astronomy will continue to help constrain cosmology.Comment: 12 pages, 8 figures, to be published in the Proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy, held July 2008 in Heidelberg, German