Exact Green's Function of the reversible diffusion-influenced reaction for an isolated pair in 2D

We derive an exact Green's function of the diffusion equation for a pair of spherical interacting particles in 2D subject to a back-reaction boundary condition.Comment: 6 pages, 1 Figur

Temperature dependent photoluminescence of organic semiconductors with varying backbone conformation

We present photoluminescence studies as a function of temperature from a series of conjugated polymers and a conjugated molecule with distinctly different backbone conformations. The organic materials investigated here are: planar methylated ladder type poly para-phenylene, semi-planar polyfluorene, and non-planar para hexaphenyl. In the longer-chain polymers the photoluminescence transition energies blue shift with increasing temperatures. The conjugated molecules, on the other hand, red shift their transition energies with increasing temperatures. Empirical models that explain the temperature dependence of the band gap energies in inorganic semiconductors can be extended to explain the temperature dependence of the transition energies in conjugated molecules.Comment: 8 pages, 9 figure

Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey

We combine 131 new medium-resolution (R~2000) J-band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5-T9. Specifically, we use an established set of spectral indices to determine surface gravity classifications for all M6-L7 objects in our sample by measuring equivalent widths (EW) of the K I lines at 1.1692, 1.1778, 1.2529 um, and the 1.2 um FeHJ absorption index. Our results are consistent with previous surface gravity measurements, showing a distinct double peak - at ~L5 and T5 - in K I EW as a function of spectral type. We analyze K I EWs of 73 objects of known ages and find a linear trend between log(Age) and EW. From this relationship, we assign age ranges to the very low gravity, intermediate gravity, and field gravity designations for spectral types M6-L0. Interestingly, the ages probed by these designations remain broad, change with spectral type, and depend on the gravity sensitive index used. Gravity designations are useful indicators of the possibility of youth, but current datasets cannot be used to provide a precise age estimate.Comment: 33 pages, 13 figures, ApJ in pres

Snapshots of a molecular swivel in action

Members of the serine family of site-specific recombinases exchange DNA strands via 180° rotation about a central protein-protein interface. Modeling of this process has been hampered by the lack of structures in more than one rotational state for any individual serine recombinase. Here we report crystal structures of the catalytic domains of four constitutively active mutants of the serine recombinase Sin, providing snapshots of rotational states not previously visualized for Sin, including two seen in the same crystal. Normal mode analysis predicted that each tetramer's lowest frequency mode (i.e. most accessible large-scale motion) mimics rotation: two protomers rotate as a pair with respect to the other two. Our analyses also suggest that rotation is not a rigid body movement around a single symmetry axis but instead uses multiple pivot points and entails internal motions within each subunit

The link between health care spending and health outcomes for the new English Primary Care Trusts

English programme budgeting data have yielded major new insights into the link between health care spending and health outcomes. This paper updates two recent studies that have used programme budgeting data for 295 Primary Care Trusts (PCTs) in England to examine the link between spending and outcomes for several programmes of care. We use the same economic model employed in the two previous studies. It focuses on a decision maker who must allocate a fixed budget across programmes of care so as to maximize social welfare given a health production function for each programme. Two equations – a health outcome equation and an expenditure equation – are estimated for each programme (data permitting). The two previous studies employed expenditure data for 2004/05 and 2005/06 for 295 health authorities and found that in several care programmes – cancer, circulation problems, respiratory problems, gastro-intestinal problems, trauma burns and injury, and diabetes – expenditure had the anticipated negative effect on the mortality rate. Each health outcome equation was used to estimate the marginal cost of a life year saved. In 2006/07 the number of PCTs in England was reduced to 152, largely through a series of mergers. In addition, several changes were made to the methods employed to construct the programme budgeting data. This paper employs updated budgeting and mortality data for the new 152 PCTs to reestimate health production and expenditure functions, and also presents updated estimates of the marginal cost of a life year saved in each programme. Although there are some differences, the results obtained are broadly similar to those presented in our two previous studies

The link between health care spending and health outcomes: : Evidence from English programme budgeting data

This report describes preliminary results from research funded by the Health Foundation under its Quest for Quality and Improved Performance (QQuIP) initiative. For three years, each Primary Care Trust (PCT) in the English NHS has prepared data on expenditure on health care across 23 ‘programmes’ of care, based on ICD10 disease categories. These programme budgeting data seek to allocate exhaustively to disease categories all items of NHS expenditure, including expenditure on inpatient care, outpatient care, community care, primary care and pharmaceuticals and devices. In 2005 the average size of the programmes varied considerably, with the largest being mental health (£145 per head per year), circulation (£122) and cancer (£75)

Further evidence on the link between health care spending and health outcomes in England

This report describes results from research funded by the Health Foundation under its Quest for Quality and Improved Performance (QQuIP) initiative. It builds on our earlier report for the Health Foundation – The link between health care spending and health outcomes: evidence from English programme budgeting data – that took advantage of the availability of a major new dataset to examine the relationship between health care expenditure and mortality rates for two disease categories (cancer and circulation problems) across 300 English Primary Care Trusts

Tricolored Lattice Gauge Theory with Randomness: Fault-Tolerance in Topological Color Codes

We compute the error threshold of color codes, a class of topological quantum codes that allow a direct implementation of quantum Clifford gates, when both qubit and measurement errors are present. By mapping the problem onto a statistical-mechanical three-dimensional disordered Ising lattice gauge theory, we estimate via large-scale Monte Carlo simulations that color codes are stable against 4.5(2)% errors. Furthermore, by evaluating the skewness of the Wilson loop distributions, we introduce a very sensitive probe to locate first-order phase transitions in lattice gauge theories.Comment: 12 pages, 5 figures, 1 tabl

Infrared spectra of one- and two-dimensional fullerene polymer structures: RbC60 and rhombohedral C-60

We compare the infrared spectra of two types of fullerene polymers: the linear-chain RbC60 and the two-dimensional pressure-polymerized rhombohedral C-60. Both the splitting of the F-1u modes and the structure of newly activated Lines are in agreement with fully ordered structures of molecular symmetry D-2h and D-3d, respectively