Magnetically Focused Proton Irradiation of Small Volume Radiosurgery Targets Using a Triplet of Quadrupole Magnets

Proton therapy is an advantageous choice for the irradiation of tumors in proximity of critical structures due to rapid dose fall off and high dose deposition at target compared to dose at the surface of the patient (ie, peak-to-entrance dose ratio (P/E)). However, with target fields below 1.0 cm, as often encountered in proton radiosurgery, multiple Coulomb scattering (MCS) broadens proton beams leading to diminished P/E advantages and reduced dose delivery efficiency (DDE). Magnetic focusing tends to counteract MCS and is a promising method to reduce these undesirable effects. The purpose of this research is to investigate the advantages of proton magnetic focusing with a triplet of quadrupole rare earth permanent magnets

Validation of a skinfold based index for tracking proportional changes in lean mass

BACKGROUND: The lean mass index (LMI) is a new empirical measure that tracks within‐subject proportional changes in body mass adjusted for changes in skinfold thickness. OBJECTIVE: To compare the ability of the LMI and other skinfold derived measures of lean mass to monitor changes in lean mass. METHODS: 20 elite rugby union players undertook full anthropometric profiles on two occasions 10 weeks apart to calculate the LMI and five skinfold based measures of lean mass. Hydrodensitometry, deuterium dilution, and dual energy x ray absorptiometry provided a criterion choice, four compartment (4C) measure of lean mass for validation purposes. Regression based measures of validity, derived for within‐subject proportional changes through log transformation, included correlation coefficients and standard errors of the estimate. RESULTS: The correlation between change scores for the LMI and 4C lean mass was moderate (0.37, 90% confidence interval −0.01 to 0.66) and similar to the correlations for the other practical measures of lean mass (range 0.26 to 0.42). Standard errors of the estimate for the practical measures were in the range of 2.8–2.9%. The LMI correctly identified the direction of change in 4C lean mass for 14 of the 20 athletes, compared with 11 to 13 for the other practical measures of lean mass. CONCLUSIONS: The LMI is probably as good as other skinfold based measures for tracking lean mass and is theoretically more appropriate. Given the impracticality of the 4C criterion measure for routine field use, the LMI may offer a convenient alternative for monitoring physique changes, provided its utility is established under various conditions

Improving access to primary care:a mixed-methods approach studying a new review appointment system in a Scottish GP practice

A Scottish general practitioner (GP) practice proposed an improvement intervention, shorter pre-bookable ‘review’ appointments, to increase appointment capacity and meet their patients’ demand for appointments. Staff are now able to pre-book these review appointments for patients, guaranteeing that the patient will see the same GP or advanced nurse practitioner (ANP) for both initial and review appointments. By shortening the review appointments, more patients were seen each day, hence the appointment capacity increased. The aim of this project was to examine the impact of the improvement intervention, pre-bookable review appointments, using a mixed-methods approach. Ethnographic methods (non-participant observation, participant observation and eight semistructured interviews with administrative staff) provided qualitative data, to understand the appointment system and to identify areas for further improvement. Quantitative data were then collected to assess: the number of patients receiving ‘on the day’ appointments, with the aim for this to be 95% (outcome measure); by how much the number of appointments available had increased (process measure) and the administrative staff workload (balancing measure). During a 7-week period, 3 months post-intervention, a median of 93% of patients received an ‘on the day’ appointment when they phoned for one between 08:00 and 09:00. The number of appointments available increased by 43%. Administrative staff workload (number of calls received per day) remained the same. Patients prefer being able to book in to see the same GP (continuity of care) and the ability to book in advance. Administrative staff workload decreased in terms of dealing with less frustrated patients. Main suggestions for improvement include introducing later appointments for workers and text reminders for pre-booked (review and online) appointments. The introduction of pre-bookable review appointments improved patient accessibility in the practice. Next steps for improving the appointment system include gaining clinician (GP/ANP) opinions on review appointments and trialling later appointments

Incorporation of Multiple Coulomb Scattering in the Prediction of Optimal Focal Lengths in Magnetically Focused Proton Radiosurgery

Magnetic focusing of protons is a promising approach to improve patient radiation dose distribution in proton radiosurgery. The paths of individual protons are affected by multiple atomic deflections (multiple Coulomb scattering [MCS]) and affect overall beam characteristics in the patient. The purpose of this project is to account for the effects of MCS in the optimization of focal lengths in magnetically focused proton radiosurgery

QED Model of Resonance Phenomena in Quasionedimensional Multichain Qubit Systems with Axial Symmetry

The analytical solution of the task of the interaction of quantized EM-field with multichain quasionedimensional axially symmetric qubit system by taking into account both the intrachain and interchain qubit coupling has been obtained for the first time. The appearance of additional lines in optical spectra of quasionedimensional systems strongly interacting with EM-field is predicted. They are result of nonstationary registration conditions, to be consequence of Rabi wave packet formation and correspond to Fourier transformation of revival part of Rabi wave packets in temporal dependence of the integral inversion. It is argued the applicability of Su-Schrieffer-Heeger-model of organic conductors for perfect quasionedimensional carbon zigzag shaped nanotubes to be consequence of 2D-1D transition with diameter decrease.Comment: 7 pages, 2 figure

Spin-other-orbit operator in the tensorial form of second quantization

The tensorial form of the spin-other-orbit interaction operator in the formalism of second quantization is presented. Such an expression is needed to calculate both diagonal and off-diagonal matrix elements according to an approach, based on a combination of second quantization in the coupled tensorial form, angular momentum theory in three spaces (orbital, spin and quasispin), and a generalized graphical technique. One of the basic features of this approach is the use of tables of standard quantities, without which the process of obtaining matrix elements of spin-other-orbit interaction operator between any electron configurations is much more complicated. Some special cases are shown for which the tensorial structure of the spin-other-orbit interaction operator reduces to an unusually simple form

Estimates of electronic interaction parameters for LaMMO3_3 compounds (MM=Ti-Ni) from ab-initio approaches

We have analyzed the ab-initio local density approximation band structure calculations for the family of perovskite oxides, La$M$O$_3$ with $M$=Ti-Ni within a parametrized nearest neighbor tight-binding model and extracted various interaction strengths. We study the systematics in these interaction parameters across the transition metal series and discuss the relevance of these in a many-body description of these oxides. The results obtained here compare well with estimates of these parameters obtained via analysis of electron spectroscopic results in conjunction with the Anderson impurity model. The dependence of the hopping interaction strength, t, is found to be approximately $r^{-3}$.Comment: 18 pages; 1 tex file+9 postscript files (appeared in Phys Rev B Oct 15,1996

Van Hove Excitons and High-Tc_c Superconductivity: VIIIC Dynamic Jahn-Teller Effects vs Spin-Orbit Coupling in the LTO Phase of La2−x_{2-x}Srx_xCuO4_4

The possible role of the van Hove singularity (vHs) in stabilizing the low-temperature orthorhombic (LTO) phase transition in La$_{2-x}$\-Sr$_x$\-CuO$_ 4$ (LSCO) is discussed. It is found that the vHs can drive a structural distortion in two different ways, either due to spin-orbit coupling or to dynamic Jahn-Teller (JT) effects. This paper discusses the latter effect in some detail. It is shown that a model Hamiltonian introduced earlier to describe the coupled electron -- octahedral tilt motions (`cageons') has a series of phase transitions, from a high-temperature disordered JT phase (similar to the high-temperature tetragonal phase of LSCO) to an intermediate temperature dynamic JT phase, of average orthorhombic symmetry (the LTO phase) to a low temperature static JT phase (the low temperature tetragonal phase). For some parameter values, the static JT phase is absent.Comment: 28 pages plain TeX, 14 figures available upon request, NU-MARKIEWIC-93-0