Large-angle scattering and quasi-elastic barrier distributions

We study in detail the barrier distributions extracted from large-angle quasi-elastic scattering of heavy ions at energies near the Coulomb barrier. Using a closed-form expression for scattering from a single barrier, we compare the quasi-elastic barrier distribution with the corresponding test function for fusion. We examine the isocentrifugal approximation in coupled-channels calculations of quasi-elastic scattering and find that for backward angles, it works well, justifying the concept of a barrier distribution for scattering processes. This method offers an interesting tool for investigating unstable nuclei. We illustrate this for the $^{32}$Mg + $^{208}$Pb reaction, where the quadrupole collectivity of the neutron-rich $^{32}$Mg remains to be clarified experimentally.Comment: 26 pages, 10 eps figure

Immaturity, Normative Competence, and Juvenile Transfer: How (Not) to Punish Minors for Major Crimes

This essay critically examines the national trend to get tough on juvenile crime by making it easier to transfer juvenile offenders to adult criminal court. It assesses this trend in light of different rationales for punishment, arguing that immaturity provides retributive, deterrent, and corrective reasons to punish juvenile crime differently than otherwise similar adult crime. Insofar as retributive concepts determine whom to punish and how much to punish, it is especially important that immaturity involves diminished normative competence and, hence, diminished responsibility. In defending a traditional approach to juvenile criminal justice against the reforms embodied in the transfer trend, the essay critically considers an alternative proposal that abolishes the juvenile court and requires a unitary system of criminal justice but treats immaturity as a mitigating factor at sentencing. Though it appears to be a more radical reform, this proposal accepts the traditional idea, rejected in the transfer trend, that immaturity implies differential desert and punishment. Despite the appeal of this non-traditional proposal for accommodating immaturity, it is rejected for sacrificing the demands of individualized justice

Effect of lightning strike on bromine intercalated graphite fiber/epoxy composites

Laminar composites were fabricated from pristine and bromine intercalated pitch based graphite fibers. It was found that laminar composites could be fabricated using either pristine or intercalated graphite fibers using standard fabrication techniques. The intercalated graphite fiber composites had electrical properties which were markedly improved over both the corresponding pitch based and polyacrylonitrile (PAN) based composites. Despite composites resistivities more than an order of magnitude lower for pitch based fiber composites, the lightning strike resistance was poorer than that of the Pan based fiber composites. This leads to the conclusion that the mechanical properties of the pitch fibers are more important than electrical or thermal properties in determining the lightning strike resistance. Based on indicated lightning strike tolerance for high elongation to failure materials, the use of vapor grown, rather than pitch based graphite fibers appears promising

Revised theory of the magnetic surface anisotropy of impurities in metallic mesoscopic samples

In several experiments the magnitude of the contribution of magnetic impurities to the Kondo resistivity shows size dependence in mesoscopic samples. It was suggested ten years ago that magnetic surface anisotropy can be responsible for the size dependence in cases where there is strong spin-orbit interaction in the metallic host. The anisotropy energy has the form $\Delta E=K_d ({\bf n}{\bf S})^2$ where ${\bf n}$ is the vector perpendicular to the plane surface, ${\bf S}$ is the spin of the magnetic impurity and $K_d>0$ is inversely proportional to distance $d$ measured from the surface. It has been realized that in the tedious calculation an unjustified approximation was applied for the hybridizations of the host atom orbitals with the conduction electrons which depend on the position of the host atoms. Namely, the momenta of the electrons were replaced by the Fermi momentum $k_F$. That is reinvestigated considering the $k$-dependence which leads to singular energy integrals and in contrary to the previous result $K_d$ is oscillating like $\sin (2 k_F d)$ and the distance dependence goes like $1/d^3$ in the asymptotic region. As the anisotropy is oscillating, for integer spin the ground state is either a singlet or a doublet depending on distance $d$, but in the case of the doublet there is no direct electron induced transition between those two states at zero temperature. Furthermore, for half-integer ($S > 1/2$) spin it is always a doublet with direct transition only in half of the cases.Comment: 10 pages, 4 figure

Development and evaluation of the elastic recovery concept for expandable space structures

Elastic recovery of expandable space structure

Generalized rotational hamiltonians from nonlinear angular momentum algebras

Higgs algebras are used to construct rotational Hamiltonians. The correspondence between the spectrum of a triaxial rotor and the spectrum of a cubic Higgs algebra is demonstrated. It is shown that a suitable choice of the parameters of the polynomial algebra allows for a precise identification of rotational properties. The harmonic limit is obtained by a contraction of the algebra, leading to a linear symmetry.Comment: 3 figures, 6 pages, 15 references. Phys. Rev. C (in press, ms CZ10038

Electron self-energy in A3C60 (A=K, Rb): Effects of t1u plasmon in GW approximation

The electron self-energy of the t1u states in A3C60 (A=K, Rb) is calculated using the so-called GW approximation. The calculation is performed within a model which considers the t1u charge carrier plasmon at 0.5 eV and takes into account scattering of the electrons within the t1u band. A moderate reduction (35 %) of the t1u band width is obtained.Comment: 4 pages, revtex, 1 figure more information at http://www.mpi-stuttgart.mpg.de/dokumente/andersen/fullerene

Approach to the extremal limit of the Schwarzschild-de Sitter black hole

The quasinormal-mode spectrum of the Schwarzschild-de Sitter black hole is studied in the limit of near-equal black-hole and cosmological radii. It is found that the mode_frequencies_ agree with the P"oschl-Teller approximation to one more order than previously realized, even though the effective_potential_ does not. Whether the spectrum approaches the limiting one uniformly in the mode index is seen to depend on the chosen units (to the order investigated). A perturbation framework is set up, in which these issues can be studied to higher order in future.Comment: REVTeX4, 4pp., no figures. N.B. "Alec" is my first, and "Maassen van den Brink" my family name. v2: added numerical verificatio