Evaluation of atomic constants for optical radiation, volume 1

Atomic constants for optical radiation are discussed which include transition probabilities, line strengths, and oscillator strengths for both dipole and quadrupole transitions, as well as the associated matrix elements needed for line broadening calculations. Atomic constants were computed for a wide selection of elements and lines. An existing computer program was used, with modifications to include, in an approximate manner, the effect of equivalent electrons, and to enable reordering and restructuring of the output for publication. This program is suitable for fast, low cost computation of the optical constants, using the Coulomb approximation formalism for LS coupling

Electric field effect modulation of transition temperature, mobile carrier density and in-plane penetration depth in NdBa2Cu3O(7-delta) thin films

We explore the relationship between the critical temperature, T_c, the mobile areal carrier density, n_2D, and the zero temperature magnetic in-plane penetration depth, lambda_ab(0), in very thin underdoped NdBa2Cu3O{7-delta} films near the superconductor to insulator transition using the electric field effect technique. We observe that T_c depends linearly on both, n_2D and lambda_ab(0), the signature of a quantum superconductor to insulator (QSI) transition in two dimensions with znu-bar where z is the dynamic and nu-bar the critical exponent of the in-plane correlation length.Comment: 4 pages, 4 figure

Hydrogen/oxygen auxiliary propulsion technology

A survey is provided of hydrogen/oxygen (H/O) auxiliary propulsion system (APS) concepts and low thrust H/O rocket technology. A review of H/O APS studies performed for the Space Shuttle, Space Tug, Space Station Freedom, and Advanced Manned Launch System programs is given. The survey also includes a review of low thrust H/O rocket technology programs, covering liquid H/O and gaseous H/O thrusters, ranging from 6600 N (1500 lbf) to 440 mN (0.1 lbf) thrust. Ignition concepts for H/O thrusters and high temperature, oxidation resistant chamber materials are also reviewed

Evidence for charged critical behavior in the pyrochlore superconductor RbOs2O6

We analyze magnetic penetration depth data of the recently discovered superconducting pyrochlore oxide RbOs2O6. Our results strongly suggest that in RbOs2O6 charged critical fuctuations dominate the temperature dependence of the magnetic penetration depth near Tc. This is in contrast to the mean-field behavior observed in conventional superconductors and the uncharged critical behavior found in nearly optimally doped cuprate superconductors. However, this finding agrees with the theoretical predictions for charged criticality and the charged criticality observed in underdoped YBa2Cu3O6.59.Comment: 5 pages, 4 figure

Z-Pencils

The matrix pencil (A,B) = {tB-A | t \in C} is considered under the assumptions that A is entrywise nonnegative and B-A is a nonsingular M-matrix. As t varies in [0,1], the Z-matrices tB-A are partitioned into the sets L_s introduced by Fiedler and Markham. As no combinatorial structure of B is assumed here, this partition generalizes some of their work where B=I. Based on the union of the directed graphs of A and B, the combinatorial structure of nonnegative eigenvectors associated with the largest eigenvalue of (A,B) in [0,1) is considered.Comment: 8 pages, LaTe

Weak lensing evidence for a filament between A222/A223

We present a weak lensing analysis and comparison to optical and X-ray maps of the close pair of massive clusters A222/223. Indications for a filamentary connection between the clusters are found and discussed.Comment: 6 pages, 1 figure. To appear in Proc. IAU Colloquium 195: Outskirts of Galaxy Clusters - Intense Life in the Suburbs. Version with higher resolution available at http://www.astro.uni-bonn.de/~dietrich/torino_proc.ps.g

The Determinants and Impact of Property Rights: Land Titles on the Brazilian Frontier

This paper provides new empirical results regarding the demand and supply of title, its impact on land value, and its effects on agricultural investment on Brazilian frontiers. We use survey data from 1992 and 1993 from the state of Par  with data on the characteristics of the settlers, land tenure, land agencies involved, land values, and investment. We then turn to census data from the Brazilian agricultural census from 1940 through 1985, with observations at the municipio (county) level to examine the development of property rights to land in the southern state of Paran  during the agricultural boom between 1940 and 1970 and in the Amazon state of Par  during the period of rapid migration to the region after 1970. By examining frontiers we can follow the rise in land values, the increase in the demand for title, and the response of government. The empirical findings support the predictions of the theory regarding the effects of title and investment on land value, the role of expected change in value on demand for title, and the contribution of title in promoting investment. Governments, however, have not exactly followed the predictions of the analytical framework in supplying title. Political and bureaucratic factors play an important role in the government response to demands for title. This result suggests that researchers must pay special attention to the complex political process by which property rights are assigned in studying the emergence of tenure institutions.

Low-energy local density of states of the 1D Hubbard model

We examine the local density of states (DOS) at low energies numerically and analytically for the Hubbard model in one dimension. The eigenstates represent separate spin and charge excitations with a remarkably rich structure of the local DOS in space and energy. The results predict signatures of strongly correlated excitations in the tunneling probability along finite quantum wires, such as carbon nanotubes, atomic chains or semiconductor wires in scanning tunneling spectroscopy (STS) experiments. However, the detailed signatures can only be partly explained by standard Luttinger liquid theory. In particular, we find that the effective boundary exponent can be negative in finite wires, which leads to an increase of the local DOS near the edges in contrast to the established behavior in the thermodynamic limit.Comment: 6 pages, 4 figures, more information can be found at http://www.physik.uni-kl.de/eggert/papers/index.htm

On the occurrence of Berezinskii-Kosterlitz-Thouless behavior in highly anisotropic cuprate superconductors

The conflicting observations in the highly anisotropic Bi2Sr2CaCu2O8+x, vidence for BKT behavior emerging from magnetization data and smeared 3D-xy behavior, stemming form the temperature dependence of the magnetic in-plane penetration depth are traced back to the rather small ratio, gsic+/gsic-=0.45, between the c-axis correlation length probed above (+) and below (-) Tc, and the comparatively large anisotropy. The latter leads to critical amplitudes gsic0+,-which are substantially smaller than the distance between two CuO2 double layers. In combination with gsic+/gsic-=0.45 and in contrast to the situation below Tc the c-axis correlation length gsic exceeds the distance between two CuO2 double layers very close to Tc only. Below this narrow temperature regime where 3D-xy fluctuations dominate, there is then an extended temperature regime where the units with two CuO2 double layers are nearly uncoupled so that 2D thermal fluctuations dominate and BKT features are observable.Comment: 4 pages, 4 figure