The spectroscopic parameters of sodium cyanide, NaCN (X 1A'), revisited

The study of the rotational spectrum of NaCN (X $^1$A') has recently been extended in frequency and in quantum numbers. Difficulties have been encountered in fitting the transition frequencies within experimental uncertainties. Various trial fits traced the difficulties to the incomplete diagonalization of the Hamiltonian. Employing fewer spectroscopic parameters than before, the transition frequencies could be reproduced within experimental uncertainties on average. Predictions of $a$-type $R$-branch transitions with $K_a \le 7$ up to 570 GHz should be reliable to better than 1 MHz. In addition, modified spectroscopic parameters have been derived for the 13C isotopic species of NaCN.Comment: 5 pages, no figure, J. Mol. Spectrosc., appeared; CDMS links update

Flavor Changing Processes in Supersymmetric Models with Hybrid Gauge- and Gravity-Mediation

We consider supersymmetric models where gauge mediation provides the dominant contributions to the soft supersymmetry breaking terms while gravity mediation provides sub-dominant yet non-negligible contributions. We further assume that the gravity-mediated contributions are subject to selection rules that follow from a Froggatt-Nielsen symmetry. This class of models constitutes an example of viable and natural non-minimally flavor violating models. The constraints from mixing in the neutral K system imply that the modifications to the Standard Model predictions for mixing in the neutral B_d and B_s systems are generically at most at the percent level, but can be of order ten percent for large $\tan \beta$. The modifications for the neutral D system mixing are generically at most of order a few percent, but in a special subclass of models they can be of order one. We point out $\Delta B=1$ processes relevant for flavor violation in hybrid mediation.Comment: 30 pages, 3 figure

Osmium isotope evidence for two pulses of increased continental weathering linked to Early Jurassic volcanism and climate change

Large igneous provinces (LIPs) are proposed to have caused a number of episodes of abrupt environmental change by increasing atmospheric CO2 levels, which were subsequently alleviated by drawdown of CO2 via enhanced continental weathering and burial of organic matter. Here the sedimentary records of two such episodes of environmental change, the Toarcian oceanic anoxic event (T-OAE) and preceding Pliensbachian–Toarcian (Pl-To) event (both possibly linked to the Karoo-Ferrar LIP), are investigated using a new suite of geochemical proxies that have not been previously compared. Stratigraphic variations in osmium isotope (187Os/188Os) records are compared with those of mercury (Hg) and carbon isotopes (d13C) in samples from the Mochras core, Llanbedr Farm, Cardigan Bay Basin, Wales. These sedimentary rocks are confirmed as recording an open-marine setting by analysis of molybdenum/uranium enrichment trends, indicating that the Os isotope record in these samples reflects the isotopic composition of the global ocean. The Os isotope data include the first results across the Pl-To boundary, when seawater 187Os/188Os increased from ~0.40 to ~0.53, in addition to new data that show elevated 187Os/188Os (from ~0.42 to ~0.68) during the T-OAE. Both increases in 187Os/188Os correlate with negative carbon isotope excursions and increased mercury concentrations, supporting an interplay between terrestrial volcanism, weathering, and climate that was instrumental in driving these distinct episodes of global environmental change. These observations also indicate that the environmental impact of the Karoo-Ferrar LIP was not limited solely to the T-OAE

NLTE wind models of hot subdwarf stars

We calculate NLTE models of stellar winds of hot compact stars (central stars of planetary nebulae and subdwarf stars). The studied range of subdwarf parameters is selected to cover a large part of these stars. The models predict the wind hydrodynamical structure and provide mass-loss rates for different abundances. Our models show that CNO elements are important drivers of subdwarf winds, especially for low-luminosity stars. We study the effect of X-rays and instabilities on these winds. Due to the line-driven wind instability, a significant part of the wind could be very hot.Comment: 7 pages, to appear in Astrophysics and Space Science. The final publication will be available at springerlink.com

Canonical Forms in Interactive Exercise Assistants

Interactive exercise assistants support students in practicing exercises, and acquiring procedural skills. Many mathematical topics can be practiced in such assistants. Ideally, an interactive exercise assistant not only validates final answers, but also comments on intermediate steps submitted by a student, provides hints on how to proceed, and presents worked-out examples. For these purposes, fine control over the symbolic simplification procedures of the underlying mathematical machinery is needed. In this paper, we introduce views for mathematical expressions. A view defines an equivalence relation by choosing a canonical form of mathematical expressions. We use views to track and recognize intermediate answers, to help in presenting expressions to a user, and to control the granularity of the steps in worked-out examples. We develop the concept of a view, discuss the laws it satisfies, and show how views are composed, which means that they can be used for multiple exercise classes.

Large Non-perturbative Effects of Small \Delta m^2_{21}/\Delta m^2_{31} and \sin \theta_{13} on Neutrino Oscillation and CP Violation in Matter

In the framework of three generations, we consider the CP violation in neutrino oscillation with matter effects. At first, we show that the non-perturbative effects of two small parameters, \Delta m_{21}^2/\Delta m_{31}^2 and \sin \theta_{13}, become more than 50% in certain ranges of energy and baseline length. This means that the non-perturbative effects should be considered in detailed analysis in the long baseline experiments. Next, we propose a method to include these effects in approximate formulas for oscillation probabilities. Assuming the two natural conditions, \theta_{23}=45^\circ and the fact that the matter density is symmetric, a set of approximate formulas, which involve the non-perturbative effects, has been derived in all channels.Comment: 25 pages, 4 figures, version to appear in JHE

The Persistency of the India-Pakistan Conflict: Chances and Obstacles of the Bilateral Composite Dialogue

This article investigates the underlying causes for the persistency of the India–Pakistan conflict and, on this basis, the chances and obstacles of the bilateral composite dialogue initiated in 2004. In particular, it wants to provide a theoretically grounded account of the factors that facilitated and constrained the bilateral composite dialogue process. Drawing on the regional security complex theory, this article examines the rivalry between the two South Asian nuclear powers on four levels of analysis: the domestic, the regional, the interregional and the global level. The analysis shows that there have been some substantial changes on all four levels in the recent decade or so and that these changes have provided more beneficial conditions for a peace process. These changes include, inter alia, India’s new regional policy, the consequences of the 9/11 terrorist attacks for the region and India’s growing power capacities. However, major obstacles to the India–Pakistan dialogue and a permanent conflict resolution continue to persist: the dominant role of the military in Pakistan, conflicting national identities and the still partially contested nature of statehood in India and Pakistan, which is in the case of Pakistan linked to the growing power of Islamic fundamentalists

Mitotic Potential of the Enamel Organ of the Rhesus Monkey

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66907/2/10.1177_00220345650440062901.pd

A progressive refinement approach for the visualisation of implicit surfaces

Visualising implicit surfaces with the ray casting method is a slow procedure. The design cycle of a new implicit surface is, therefore, fraught with long latency times as a user must wait for the surface to be rendered before being able to decide what changes should be introduced in the next iteration. In this paper, we present an attempt at reducing the design cycle of an implicit surface modeler by introducing a progressive refinement rendering approach to the visualisation of implicit surfaces. This progressive refinement renderer provides a quick previewing facility. It first displays a low quality estimate of what the final rendering is going to be and, as the computation progresses, increases the quality of this estimate at a steady rate. The progressive refinement algorithm is based on the adaptive subdivision of the viewing frustrum into smaller cells. An estimate for the variation of the implicit function inside each cell is obtained with an affine arithmetic range estimation technique. Overall, we show that our progressive refinement approach not only provides the user with visual feedback as the rendering advances but is also capable of completing the image faster than a conventional implicit surface rendering algorithm based on ray casting

Analytic and Reidemeister torsion for representations in finite type Hilbert modules

For a closed Riemannian manifold we extend the definition of analytic and Reidemeister torsion associated to an orthogonal representation of fundamental group on a Hilbert module of finite type over a finite von Neumann algebra. If the representation is of determinant class we prove, generalizing the Cheeger-M\"uller theorem, that the analytic and Reidemeister torsion are equal. In particular, this proves the conjecture that for closed Riemannian manifolds with positive Novikov-Shubin invariants, the L2 analytic and Reidemeister torsions are equal.Comment: 78 pages, AMSTe