Assessing smoking status in children, adolescents and adults: cotinine cut-points revisited

Aims To reassess saliva cotinine cut-points to discriminate smoking status. Cotinine cut-points that are in use were derived from relatively small samples of smokers and non-smokers 20 or more years ago. It is possible that optimal cut-points may have changed as prevalence and exposure to passive smoking have declined. Design Cross-sectional survey of the general population, with assessment of self-reported smoking and saliva cotinine. Participants A total of 58 791 respondents aged 4 years and older in the Health Survey for England for the years 1996-2004 who provided valid saliva cotinine specimens. Measures Saliva cotinine concentrations, demographic variables, self-reported smoking, presence or absence of smoking in the home, a composite index of social disadvantage derived from occupation, housing tenure and access to a car. Findigns A cut-point of 12 ng/ml performed best overall, with specificity of 96.9% and sensitivity of 96.7% in discriminating confirmed cigarette smokers from never regular smokers. This cut-point also identified correctly 95.8% of children aged 8-15 years smoking six or more cigarettes a week. There was evidence of substantial misreport in claimed ex-smokers, especially adolescents (specificity 72.3%) and young adults aged 16-24 years (77.5%). Optimal cut-points varied by presence (18 ng/ml) or absence (5 ng/ml) of smoking in the home, and there was a gradient from 8 ng/ml to 18 ng/ml with increasing social disadvantage. Conclusions The extent of non-smokers' exposure to other people's tobacco smoke is the principal factor driving optimal cotinine cut-points. A cut-point of 12 ng/ml can be recommended for general use across the whole age range, although different cut-points may be appropriate for population subgroups and in societies with differing levels of exposure to secondhand smoke

Variational integrators, the Newmark scheme, and dissipative systems

Variational methods are a class of symplectic-momentum integrators for ODEs. Using these schemes, it is shown that the classical Newmark algorithm is structure preserving in a non-obvious way, thus explaining the observed numerical behavior. Modifications to variational methods to include forcing and dissipation are also proposed, extending the advantages of structure preserving integrators to non-conservative systems

The Principal Axis of the Virgo Cluster

Using accurate distances to individual Virgo cluster galaxies obtained by the method of Surface Brightness Fluctuations, we show that Virgo's brightest ellipticals have a remarkably collinear arrangement in three dimensions. This axis, which is inclined by 10 to 15 degrees from the line of sight, can be traced to even larger scales where it appears to join a filamentary bridge of galaxies connecting Virgo to the rich cluster Abell 1367. The orientations of individual Virgo ellipticals also show some tendency to be aligned with the cluster axis, as does the jet of the supergiant elliptical M87. These results suggest that the formation of the Virgo cluster, and its brightest member galaxies, have been driven by infall of material along the Virgo-A1367 filament.Comment: 8 pages, 4 figures, accepted for publication in ApJ Letter

A Modified Stern-Gerlach Experiment Using a Quantum Two-State Magnetic Field

The Stern-Gerlach experiment has played an important role in our understanding of quantum behavior. We propose and analyze a modified version of this experiment where the magnetic field of the detector is in a quantum superposition, which may be experimentally realized using a superconducting flux qubit. We show that if incident spin-$1/2$ particles couple with the two-state magnetic field, a discrete target distribution results that resembles the distribution in the classical Stern-Gerlach experiment. As an application of the general result, we compute the distribution for a square waveform of the incident fermion. This experimental setup allows us to establish: (1) the quantization of the intrinsic angular momentum of a spin-$1/2$ particle, and (2) a correlation between EPR pairs leading to nonlocality, without necessarily collapsing the particle's spin wavefunction.Comment: 12 pages, 2 figure

Nonsmooth Lagrangian mechanics and variational collision integrators

Variational techniques are used to analyze the problem of rigid-body dynamics with impacts. The theory of smooth Lagrangian mechanics is extended to a nonsmooth context appropriate for collisions, and it is shown in what sense the system is symplectic and satisfies a Noether-style momentum conservation theorem. Discretizations of this nonsmooth mechanics are developed by using the methodology of variational discrete mechanics. This leads to variational integrators which are symplectic-momentum preserving and are consistent with the jump conditions given in the continuous theory. Specific examples of these methods are tested numerically, and the long-time stable energy behavior typical of variational methods is demonstrated

Very Extended E8E_8 and A8A_8 at low levels, Gravity and Supergravity

We define a level for a large class of Lorentzian Kac-Moody algebras. Using this we find the representation content of very extended $A_{D-3}$ and $E_8$ (i.e. $E_{11}$) at low levels in terms of $A_{D-1}$ and $A_{10}$ representations respectively. The results are consistent with the conjectured very extended $A_8$ and $E_{11}$ symmetries of gravity and maximal supergravity theories given respectively in hep-th/0104081 and hep-th/0107209. We explain how these results provided further evidence for these conjectures.Comment: 16 pages, plain tex (equation 3.3 modified and one reference expanded

Globular Cluster Population of Hickson Compact Group 22a and 90c

We present the first measurement of the globular cluster populations of galaxies in Hickson compact groups, in order to investigate the effect of these high density environments on the formation and evolution of globular cluster systems. Based on V and R band images that we obtained of HCG 22a and HCG 90c with the ESO New Technology Telescope (NTT), we find a total globular cluster population of $1590\pm 854$ for HCG 22a and $2136\pm 718$ for 90c. The specific frequency for HCG 22a was found to be $S_{N}=1.9\pm 1.0$ and $S_{N}= 3.4\pm 1.1$ for HCG 90c. A power-law fit to the globular cluster radial profile of HCG 22a yields $\sigma\sim R^{-2.01\pm 0.30}$ and for HCG 90c we found $\sigma \sim R^{-1.20\pm0.16}$. A comparison of the globular cluster radial profiles with the surface brightness of the parent galaxy shows that the globular cluster systems are at least as extended as the halo light. The measured values for the specific frequency are consistent with a scenario in which the host galaxies were in a low density ``field-like'' environment when they formed their globular cluster systems.Comment: 28 pages, 13 figures, 3 tables, accepted for publication in the Astrophysical Journa

Pandemic pandemonium and primary care networks: Experiences of establishing primary care placements in a new medical school

Background: In 2018 five new medical schools were announced to support the expansion of the workforce. The Kent and Medway programme features early clinical placements in the community. These start in year one, structured as immersion weeks in Primary Care Networks. The KMMS school opened in September 2020 in the midst of the COVID-19 pandemic with all of its attendant challenges. We report on the challenges of selecting and establishing the placements in the newly established primary care networks (PCN). These offer a unique opportunity for medical students to learn about the provision of proactive personalised and co-ordinated multidisciplinary care at an early and formative stage in their careers. Over the course of the first year, multiple adjustments to the learning format were required including a move to blended learning. Summary of Work Initial: challenges included agreeing selection criteria for the PCNs before attending to the legal complexities of contracting and negotiating a service level agreement with the networks, addressing the needs of all stakeholders. Faculty development was conducted remotely. Challenges of the immersion weeks included compromises associated with lockdown restrictions, limited movement across organisations, social distancing and “shielding” students. Over the course of the immersion weeks, we moved to a blended format, navigating the challenges of recorded assessment presentations. Summary of Results: We will present a logic model evaluation of this first year of placements. This summarises the resources required, activities (aspects of implementation) as well as the outcomes. These are considered from the perspective of the school, the GP faculty and students. Discussion and Conclusions: Innovation in establishing a new medical school brings a unique set of challenges to negotiate. PCNs are contractual collaborations between practices (not legal entities), presenting a challenge for both contracting and quality evaluation. COVID-19 constraints compounded the complexities but offered a unique opportunity to observe multidisciplinary, cross organisation work at first hand in the delivery of the COVD vaccination programme. This balanced the change to a blended learning format. Take Home Messages: Flexibility is a key factor in the successful implementation of a new medical school programme involving a range of stakeholders, particularly during a pandemic