Scattering of 300-MeV positrons from cobalt and bismuth

Positrons and electrons from the Stanford Mark III linear accelerator have been scattered from cobalt and bismuth at 300 MeV. The ratio R, equal to (σ--σ+)/(σ-+σ+), has been measured at a number of angles from 10° to 45° for cobalt and from 5° to 45° for bismuth. Two experiments are reported: a high-percision experiment with poor energy resolution, suitable for measuring the small values of R found at small angles, where inelastic scattering is not important; and an experiment with somewhat lower precision but better energy resolution, suitable for measuring the larger values of R found at angles where inelastic scattering must be taken into account. The elastic scattering data are in good agreement with phase-shift calculations of Herman, Clark, and Ravenhall, who used nuclear charge distributions which fit earlier electron scattering data. The inelastic data, for which no reliable predictions exist, indicate that Rinelastic is generally smaller than Relastic. This suggests that the inelastic scattering is better described by the first Born approximation, in which R=0, than is the elastic scattering

Phase Space Evolution and Discontinuous Schr\"odinger Waves

The problem of Schr\"odinger propagation of a discontinuous wavefunction -diffraction in time- is studied under a new light. It is shown that the evolution map in phase space induces a set of affine transformations on discontinuous wavepackets, generating expansions similar to those of wavelet analysis. Such transformations are identified as the cause for the infinitesimal details in diffraction patterns. A simple case of an evolution map, such as SL(2) in a two-dimensional phase space, is shown to produce an infinite set of space-time trajectories of constant probability. The trajectories emerge from a breaking point of the initial wave.Comment: Presented at the conference QTS7, Prague 2011. 12 pages, 7 figure

Exact propagators on the lattice with applications to diffractive effects

The propagator of the discrete Schr\"odinger equation is computed and its properties are revealed through a Feynman path summation in discrete space. Initial data problems such as diffraction in discrete space and continuous time are studied analytically by the application of the new propagator. In the second part of this paper, the analogy between time propagation and 2D scattering by 1D obstacles is explored. New results are given in the context of diffraction by edges within a periodic medium. A connection with tight-binding arrays and photonic crystals is indicated.Comment: Final version with two appendices. Published in J. Phys. A: Math. Theo

Is the renewables transformation a piece of cake or a pie in the sky?

Historically, long-waves have characterized transformations of the energy systems. There is not much reason to assume that our current energy system is here to stay. One possible future option is that renewables will provide all energy needed. While many scenarios exist showing that this is technically feasible, the related costs, speed of technology diffusion and social and political acceptance of such an energy transition are fiercely debated, both in the scientific field as well as in politics. Yet, there is growing consensus that renewables are becoming established as a key building block in the energy system, irrespective of the exact shares they represent. The focus should shift from a debate surrounding the feasibility of a 100% renewable system to how we can enable a speedy and immediate upscaling

Energy poverty, institutional reform and challenges of sustainable development: the case of India

This paper assesses recent efforts by the Indian Government to tackle energy poverty and sustainable development. It focuses on the new integrated energy policy, and initiatives to disseminate improved cookstoves and develop energy alternatives for transport. The success of government initiatives in cleaner biomass cookstoves and village electrification has historically been limited, and institutional reforms in the 2000s promoted market-led and ‘user-centred’ approaches, and encouraged biofuels as a ‘pro-poor’ route to rural development and energy security. The paper argues that such interventions have reopened tensions and conflicts around land-use, intra-community inequalities and the role of corporate agendas in sustainable energy

Mobile health use in low- and high-income countries: an overview of the peer-reviewed literature.

The evolution of mobile phone technology has introduced new possibilities to the field of medicine. Combining technological advances with medical expertise has led to the use of mobile phones in all healthcare areas including diagnostics, telemedicine, research, reference libraries and interventions. This article provides an overview of the peer-reviewed literature, published between 1 August 2006 and 1 August 2011, for the application of mobile/cell phones (from basic text-messaging systems to smartphones) in healthcare in both resource-poor and high-income countries. Smartphone use is paving the way in high-income countries, while basic text-messaging systems of standard mobile phones are proving to be of value in low- and middle-income countries. Ranging from infection outbreak reporting, anti-HIV therapy adherence to gait analysis, resuscitation training and radiological imaging, the current uses and future possibilities of mobile phone technology in healthcare are endless. Multiple mobile phone based applications are available for healthcare workers and healthcare consumers; however, the absolute majority lack an evidence base. Therefore, more rigorous research is required to ensure that healthcare is not flooded with non-evidence based applications and is maximized for patient benefit

Nuclear Octupole Correlations and the Enhancement of Atomic Time-Reversal Violation

We examine the time-reversal-violating nuclear ``Schiff moment'' that induces electric dipole moments in atoms. After presenting a self-contained derivation of the form of the Schiff operator, we show that the distribution of Schiff strength, an important ingredient in the ground-state Schiff moment, is very different from the electric-dipole-strength distribution, with the Schiff moment receiving no strength from the giant dipole resonance in the Goldhaber-Teller model. We then present shell-model calculations in light nuclei that confirm the negligible role of the dipole resonance and show the Schiff strength to be strongly correlated with low-lying octupole strength. Next, we turn to heavy nuclei, examining recent arguments for the strong enhancement of Schiff moments in octupole-deformed nuclei over that of 199Hg, for example. We concur that there is a significant enhancement while pointing to effects neglected in previous work (both in the octupole-deformed nuclides and 199Hg) that may reduce it somewhat, and emphasizing the need for microscopic calculations to resolve the issue. Finally, we show that static octupole deformation is not essential for the development of collective Schiff moments; nuclei with strong octupole vibrations have them as well, and some could be exploited by experiment.Comment: 25 pages, 4 figures embedded in tex