Isospin Diffusion in Heavy-Ion Collisions and the Neutron Skin Thickness of Lead

The correlation between the thickness of the neutron skin in Pb-208, and the degree of isospin diffusion in heavy-ion collisions is examined. The same equation of state is used to compute the degree of isospin diffusion in an isospin-depedent transport model and the neutron skin thickness in the Hartree-Fock approximation. We find that skin thicknesses less than 0.15 fm are excluded by the isospin diffusion data.Comment: 5 pages, 4 figures; few minor corrections and updates; version to appear in PR

Ramifications of the Nuclear Symmetry Energy for Neutron Stars, Nuclei, and Heavy-Ion Collisions

The pervasive role of the nuclear symmetry energy in establishing some nuclear static and dynamical properties, and in governing some attributes of neutron star properties is highlighted.Comment: 8 pages, to appear in the proceedings of the International Symposium on Exotic States of Nuclear Matter (EXOCT 2007), Catania, Italy, 11-15 Jun 200

Subtype-specific plasticity of inhibitory circuits in motor cortex during motor learning.

Motor skill learning induces long-lasting reorganization of dendritic spines, principal sites of excitatory synapses, in the motor cortex. However, mechanisms that regulate these excitatory synaptic changes remain poorly understood. Here, using in vivo two-photon imaging in awake mice, we found that learning-induced spine reorganization of layer (L) 2/3 excitatory neurons occurs in the distal branches of their apical dendrites in L1 but not in the perisomatic dendrites. This compartment-specific spine reorganization coincided with subtype-specific plasticity of local inhibitory circuits. Somatostatin-expressing inhibitory neurons (SOM-INs), which mainly inhibit distal dendrites of excitatory neurons, showed a decrease in axonal boutons immediately after the training began, whereas parvalbumin-expressing inhibitory neurons (PV-INs), which mainly inhibit perisomatic regions of excitatory neurons, exhibited a gradual increase in axonal boutons during training. Optogenetic enhancement and suppression of SOM-IN activity during training destabilized and hyperstabilized spines, respectively, and both manipulations impaired the learning of stereotyped movements. Our results identify SOM inhibition of distal dendrites as a key regulator of learning-related changes in excitatory synapses and the acquisition of motor skills

Probing the equation of state of neutron-rich matter with intermediate energy heavy-ion collisions

Nuclear reactions induced by stable and/or radioactive neutron-rich nuclei provide the opportunity to pin down the equation of state of neutron-rich matter, especially the density ($\rho$) dependence of its isospin-dependent part, i.e., the nuclear symmetry energy $E_{\rm sym}$. A conservative constraint, $32(\rho /\rho_{0})^{0.7} < E_{\rm sym}(\rho ) < 32(\rho /\rho _{0})^{1.1}$, around the nuclear matter saturation density $\rho_0$ has recently been obtained from the isospin diffusion data in intermediate energy heavy-ion collisions. We review this exciting result and discuss its consequences and implications on nuclear effective interactions, radii and cooling mechanisms of neutron stars.Comment: 10 pages. Invited talks at (1) International Workshop on Nuclear Multifragmentation, Nov. 28-Dec. 1, 2005, Catania, Italy and (2) XXIX Symposium on Nuclear Physics, Jan. 3-6, 2006, Cocoyoc, Morelos, Mexic

How safe is Azeroth, or, are MMORPGs a security risk?

Massive Multiplayer Online Role Playing Games (MMORPGs) are at a basic level a networked application. Blizzard’s World of Warcraft is currently the largest example of such a type of application, with over nine million subscribers at last count. Whilst the idea of researching a game for network security may sound trivial, nine million potential backdoors into home and business computers is not. The ports used by the game, as well as authentication methods and client update programs were examined using packet analysis software. No obvious vulnerabilities were discovered as a result of this analysis. In addition to this analysis, an examination of the literature in terms of other types of attack that are present was also performed. These include such common attacks as SPAM, malware and trojans. The conclusion is that while no specific network vulnerability appears to exist in the games launcher or updater, there are still a number of other attack vectors that need to be considered and protected against