Three-dimensional Doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states

We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a ”type-II" system where the angular momentum of the excited state, F', is less than or equal to that of the ground state, F. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one-dimensional counterpart. This differs from the more commonly used “type-I" systems (F' = F +1) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, v₀, where the two forces cancel. We find that v₀² scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions

A Strange Family of Calabi-Yau 3-folds

We study the predictions of mirror symmetry for the 1-parameter family of Calabi-Yau 3-folds $\tilde{X}$ with hodge numbers $h^{11}=31,h^{21}=1$ constructed in \cite{BN}. We calculate the Picard-Fuchs differential equation associated to this family, and use it to predict the instanton numbers on the hypothetical mirror. These exhibit a strange vanishing in odd degrees. We also calculate the monodromy action on H^3(\tilde{X},\QQ) and find that it strangely predicts a positive Euler characteristic for its mirror. From a degenerate fiber of our family we construct a new rigid Calabi-Yau 3-fold. In an appendix we prove the expansion of the conifold period conjectured in \cite{ES} to hold for all 1-parameter families.Comment: 23 page

Using the EQ-5D as a performance measurement tool in the NHS

In a landmark move, the UK Department of Health (DH) is introducing the routine use of Patient Reported Outcome Measures (PROMs) as a means of measuring the performance of health care providers in improving patient health. From April 2009 all patients will be asked to complete both generic (EQ-5D) and condition specific PROMs before and after surgery for four elective procedures; the intention is to extend this to a wide range of other NHS services. The aim of this paper is to report analysis of the EQ-5D data generated from a pilot study commissioned by the DH, and to consider the implications of the results for their use as performance indicators and measures of patient benefit. The EQ-5D has the potential advantage in the context of PROMs of enabling comparisons of performance across services as well as between providers; and in facilitating assessments of the cost effectiveness of NHS services. We present two new methods we have developed for analysing and displaying EQ-5D profile data: a Paretian Classification of Health Change, and a Health Profile Grid. Using these methods, we show that EQ-5D data can readily be used to generate useful insights into differences between providers in improving overall changes in health; results are also suggestive of striking differences in changes in health between surgical procedures. We conclude by noting a number of issues that remain to be addressed in the use of PROMs data as a basis for performance indicators

Three-dimensional Doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states

We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a "type-II" system where the angular momentum of the excited state, $F'$, is less than or equal to that of the ground state, $F$. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one dimensional counterpart. This differs from the more commonly used "type-I" systems ($F'=F+1$) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, $v_{0}$, where the two forces cancel. We find that $v_{0}^{2}$ scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions.Comment: 20 pages, 7 figures. Revised version to correct several small typographical errors and clarify the discussion on page 9. Labeling of figure 1 and colours in figure 5 also changed, and additional information provided for equations 13 and 1

A Study of the Relationship Between Health and Subjective Well-being in Parkinson’s Disease Patients

Objectives: In light of the apparent disconnect between traditional measures of societal well-being such as GDP and reported levels of happiness, governments globally are turning their attention to alternative subjective measures of well-being (SWB) to aid policy decisions. In the context of health, there is therefore growing interest in understanding how measures of health-related quality of life (HRQoL), widely used in health technology appraisal, relates to SWB, and whether SWB could provide a sound basis for resource allocation decisions in health and other sectors in the future. This study investigates the relationship between HRQoL, as measured by EQ-5D, and SWB in Parkinson’s disease (PD) and the extent to which patients’ self-reported health can explain (part of) their SWB. Methods: A paper questionnaire including EQ-5D, four key SWB questions taken from the Office for National Statistics Integrated Household Survey in England and other demographic details was distributed to people with PD in the UK. Responses were used to estimate multiple regression models explaining SWB using each of the EQ-5D Index (UK weights), EQ-5D dimensions and EQ-VAS and patient socio-demographic characteristics. Results: 276 questionnaires were distributed and 183 responses received. The EQ-5D Index was a moderate predictor of SWB (adjusted R2 range 0.19-0.38 in OLS models), but EQ-VAS performed better (adjusted R2 range 0.32-0.49). Combining EQ-VAS and EQ-5D dimensions, especially anxiety/depression and mobility, and household status in some cases, yielded the best-fitting models (adjusted R2 range 0.40-0.52). Conclusions: The findings imply that EQ-VAS and some dimensions of the EQ-5D, together with key demographic data, could potentially be used to predict SWB, e.g. via mapping. However, further empirical research into the relationship between SWB and EQ-5D longitudinally, and in different disease areas, is required to corroborate these findings, and further standardisation of SWB measures is recommended

The role of the “Inter-Life” virtual world as a creative technology to support student transition into higher education

The shape of Higher Education (HE) in the UK and internationally is changing, with wider access policies leading to greater diversity and heterogeneity in contemporary student populations world-wide. Students in the 21st Century are often described as “fragmented”; meaning they are frequently working whilst participating in a full time Degree programme. Consequently, those in the HE setting are required to become “future ready” which increasingly involves the seamless integration of new digital technologies into undergraduate programmes of teaching and learning. The present study evaluated the effectiveness of the “Inter-Life” three-dimensional virtual world as a suitable Technology Enhanced Learning (TEL) tool to support the initial stages of transition from school into university. Our results demonstrate that Inter-Life is “fit for purpose” in terms of the robustness of both the educational and technical design features. We have shown that Inter-Life provides a safe space that supports induction mediated by active learning tasks using learner-generated, multi-modal transition tools. In addition, through the provision of private spaces, Inter-Life also supports and fosters the development of critical reflective thinking skills. However, in keeping with the current literature in the field, some of the students expressed a wish for more training in the functional and social skills required to navigate and experience the Inter-Life virtual world more effectively. Such findings resonate with the current debate in the field which challenges the notion of “digital natives”, but the present study has also provided some new evidence to support the role of virtual worlds for the development of a suitable community to support students undergoing transition to university

Integrating visual and tactile information in the perirhinal cortex

By virtue of its widespread afferent projections, perirhinal cortex is thought to bind polymodal information into abstract object-level representations. Consistent with this proposal, deficits in cross-modal integration have been reported after perirhinal lesions in nonhuman primates. It is therefore surprising that imaging studies of humans have not observed perirhinal activation during visual–tactile object matching. Critically, however, these studies did not differentiate between congruent and incongruent trials. This is important because successful integration can only occur when polymodal information indicates a single object (congruent) rather than different objects (incongruent). We scanned neurologically intact individuals using functional magnetic resonance imaging (fMRI) while they matched shapes. We found higher perirhinal activation bilaterally for cross-modal (visual–tactile) than unimodal (visual–visual or tactile–tactile) matching, but only when visual and tactile attributes were congruent. Our results demonstrate that the human perirhinal cortex is involved in cross-modal, visual–tactile, integration and, thus, indicate a functional homology between human and monkey perirhinal cortices