Non-adiabatic corrections to elastic scattering of halo nuclei

We derive the formalism for the leading order corrections to the adiabatic approximation to the scattering of composite projectiles. Assuming a two-body projectile of core plus loosely-bound valence particle and a model (the core recoil model) in which the interaction of the valence particle and the target can be neglected, we derive the non-adiabatic correction terms both exactly, using a partial wave analysis, and using the eikonal approximation. Along with the expected energy dependence of the corrections, there is also a strong dependence on the valence-to-core mass ratio and on the strength of the imaginary potential for the core-target interaction, which relates to absorption of the core in its scattering by the target. The strength and diffuseness of the core-target potential also determine the size of the corrections. The first order non-adiabatic corrections were found to be smaller than qualitative estimates would expect. The large absorption associated with the core-target interaction in such halo nuclei as Be11 kills off most of the non-adiabatic corrections. We give an improved estimate for the range of validity of the adiabatic approximation when the valence-target interaction is neglected, which includes the effect of core absorption. Some consideration was given to the validity of the eikonal approximation in our calculations.Comment: 14 pages with 10 figures, REVTeX4, AMS-LaTeX v2.13, submitted to Phys. Rev.

The South Seas of To-Day

The following is a chapter plus some text from the Introduction of a book published in 1926, describing a scientific expedition that cruised the Pacific in 1924. The group visited the Marquesas, Tahiti, and Rapa Iti before stopping, briefly, at Easter Island. What science was conducted is unclear. They did make a film record of the journey and the whereabouts ofthe footage they shot would be of interest, if it still exists. Of particular concern is the presence on Easter Island of a Ford automobile, described as "very, very old and decrepit ". This apparition, belonging to Mr. Edmunds, is a real mystery of Easter Island. How did it get to the island? And when?</p

Carbon Capture and Storage (CCS) pipeline operating temperature effects on UK soils: The first empirical data

This paper presents the first empirical data of soil temperature and soil moisture profiles with depth in the context of a buried Carbon Capture and Storage transportation pipeline operating at higher than ambient soil temperatures. In an experimental approach, soil temperature responses are non-linear and are raised and restricted to within 45 cm of the subsurface heat source (hypothetical pipeline). A surface heat source is included to investigate interactions of natural seasonal surface heating of soils with subsurface heat. There is no interaction between subsurface and surface heat sources in the experimental system. Soil moisture profiles vary with soil type, with overall soil moisture losses of >10% over experimental time courses. Modelled soil temperature profiles show that the ability of soils to buffer thermal movement from depths up to 1.2 m from the surface is currently inadequately represented. Measurements provide the first elementary data of soil temperature changes resulting from a subsurface heat source for more accurate modelling of soil/pipeline interactions

Nature of the Missing Near-side Amplitude in Calculations of Intermediate Energy (d,p) and (p,d) Reactions

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Interaction of Natural Organic Matter with Layered Minerals: Recent Developments in Computational Methods at the Nanoscale

The role of mineral surfaces in the adsorption, transport, formation, and degradation of natural organic matter (NOM) in the biosphere remains an active research area owing to the difficulties in identifying proper working models of both NOM and mineral phases present in the environment. The variety of aqueous chemistries encountered in the subsurface (e.g., oxic vs. anoxic, variable pH) further complicate this field of study. Recently, the advent of nanoscale probes such as X-ray adsorption spectroscopy and surface vibrational spectroscopy applied to study such complicated interfacial systems have enabled new insight into NOM-mineral interfaces. Additionally, due to increasing capabilities in computational chemistry, it is now possible to simulate molecular processes of NOM at multiple scales, from quantum methods for electron transfer to classical methods for folding and adsorption of macroparticles. In this review, we present recent developments in interfacial properties of NOM adsorbed on mineral surfaces from a computational point of view that is informed by recent experiments

An NMR-based nanostructure switch for quantum logic

We propose a nanostructure switch based on nuclear magnetic resonance (NMR) which offers reliable quantum gate operation, an essential ingredient for building a quantum computer. The nuclear resonance is controlled by the magic number transitions of a few-electron quantum dot in an external magnetic field.Comment: 4 pages, 2 separate PostScript figures. Minor changes included. One reference adde

A Bayesian Image Analysis of the Change in Tumor/Brain Contrast Uptake Induced by Radiation via Reversible Jump Markov Chain Monte Carlo

This work is motivated by a pilot study on the change in tumor/brain contrast uptake induced by radiation via quantitative Magnetic Resonance Imaging. The results inform the optimal timing of administering chemotherapy in the context of radiotherapy. A noticeable feature of the data is spatial heterogeneity. The tumor is physiologically and pathologically distinct from surrounding healthy tissue. Also, the tumor itself is usually highly heterogeneous. We employ a Gaussian Hidden Markov Random Field model that respects the above features. The model introduces a latent layer of discrete labels from an Markov Random Field (MRF) governed by a spatial regularization parameter. We further assume that conditional on the hidden labels, the observed data are independent and normally distributed, We treat the regularization parameter of the MRF, as well as the number of states of the MRF as parameters, and estimate them via the Reversible Jump Markov chain Monte Carlo algorithm. We propose a novel and nontrivial implementation of the Reversible Jump moves. The performance of the method is examined in both simulation studies and real data analysis. We report the pixel-wise posterior mean and standard deviation of the change in contrast uptake marginalized over the number of states and hidden labels. We also compare the performance with a Markov chain with fixed number of states and a parallel Expectation-Maximization approach from a frequentist perspective