Mixing and coherent structures in two-dimensional viscous flows

We introduce a dynamical description based on a probability density $\phi(\sigma,x,y,t)$ of the vorticity $\sigma$ in two-dimensional viscous flows such that the average vorticity evolves according to the Navier-Stokes equations. A time-dependent mixing index is defined and the class of probability densities that maximizes this index is studied. The time dependence of the Lagrange multipliers can be chosen in such a way that the masses m(\sigma,t):=\intdxdy \phi(\sigma,x,y,t) associated with each vorticity value $\sigma$ are conserved. When the masses $m(\sigma,t)$ are conserved then 1) the mixing index satisfies an H-theorem and 2) the mixing index is the time-dependent analogue of the entropy employed in the statistical mechanical theory of inviscid 2D flows [Miller, Weichman & Cross, Phys. Rev. A \textbf{45} (1992); Robert & Sommeria, Phys. Rev. Lett. \textbf{69}, 2776 (1992)]. Within this framework we also show how to reconstruct the probability density of the quasi-stationary coherent structures from the experimentally determined vorticity-stream function relations and we provide a connection between this probability density and an appropriate initial distribution

Increasing healthy life expectancy equitably in England by 5 years by 2035: could it be achieved?

In 2018, the UK Government’s Secretary of State for Health and Social Care articulated an ambition to increase healthy life expectancy by five years by 2035 for England, while also reducing the gap in this between the rich and the poor1. While we doubt that England – or indeed any high-income country – could achieve this ambition, we describe a set of policies with the potential to make a significant contribution

A new sampling system tailored to experimentally-derived mechanical properties of icy analogs for evolved Enceladus surface plume deposits

Enceladus is unique amongst Ocean Worlds in our Solar System: the contents of its internal ocean are continuously emitted to space by its present-day activity, and some of these materials are redeposited on the surface. This tiny moon of Saturn thus presents an opportunity to directly measure the composition of the ocean and seek evidence for habitability (including past or extant life), either by collecting and analyzing plume particles as previously proposed by Discovery and New Frontiers mission concepts, or via more ambitious mission concepts that involve landing, surface sampling and analysis, and potential deployment of subsurface probes to reach the ocean itself (Hofgartner et al., this meeting). However, the low surface gravity (1% of Earth’s) and extreme cryogenic conditions in the South Pole regions (~ 50 K, away from the Tiger Stripes) raises questions: how to best sample the upper ~ 1 cm of the surface around a lander, made of most freshly deposited plume materials? What are the expected properties of these materials, i.e. how fast does sintering proceed and how strong would these materials be as function of their exposure age? We provide answers to these questions via a two-pronged approach. First, we surveyed experimentally the time evolution of mechanical strength of large samples of ice spherules at several temperatures. A custom sample preparation system has been developed to synthesize ice spheres with a grain size distribution of mean ~ 12 microns. The samples are subsequently held at temperatures of -30, -50, and -80 C, over extended periods of time (up to 9 months at time of writing), and their strength is tested at frequent intervals using cone penetration tests. The data obtained to date suggests that the observed temperature dependence of the strength evolution is commensurate with expectations from vapor diffusion. Second, we developed a new sampling system that enables rapid sampling and transfer of surface materials into receptacles. Those receptacles can then deposit the sampled materials into the inlet of an instrument dedicated to analyzing the chemical composition of these materials and seek tracers of past or extant life. The geometry of the system and principles of operation have been established and validated by experimental tests, as well as dynamical simulations

An observational study of retail availability and in-store marketing of e-cigarettes in London: potential to undermine recent tobacco control gains?

OBJECTIVES: E-cigarette companies and vendors claim the potential of e-cigarettes to help smokers reduce or quit tobacco use. E-cigarettes also have the potential to renormalise smoking. The purpose of this study was to describe the availability and in-store marketing of e-cigarettes in London, UK stores selling tobacco and alcohol. DESIGN: Observational study. SETTING: Small and large stores selling alcohol and tobacco in London, UK. PRIMARY AND SECONDARY OUTCOME MEASURES: The number of stores selling e-cigarettes, the number of stores with an interior or exterior e-cigarette advertisement, the number of stores with an e-cigarette point-of-sale movable display, store size, deprivation index score for store's corresponding lower super output area. RESULTS: Audits were completed in 108 of 128 selected stores. 62 of the audited stores (57%) sold e-cigarettes. E-cigarette availability was unrelated to store size. There was a statistically non-significant trend towards increased availability in more deprived areas (p=0.069). 31 of the 62 stores (50%) selling e-cigarettes had a point-of-sale movable display, with all but one found in small stores. Two small stores had interior advertisements and eight had exterior advertisements. No advertisements were observed in large stores. CONCLUSIONS: This audit revealed widespread availability of e-cigarettes and in-store marketing in London, UK. Even if e-cigarettes prove to be an effective cessation aid, their sale and use are resulting in an increasing public presence of cigarette-like images and smoking behaviour. After decades of work to denormalise smoking, these findings raise the question of whether e-cigarettes are renormalising smoking

Impact of health warning labels communicating the risk of cancer on alcohol selection: An online experimental study

Background and Aims: Evidence from tobacco research suggests that health warning labels (HWLs) depicting the adverse consequences of consumption change smoking behaviours, with image-and-text (also known as ‘pictorial’ or ‘graphic’) HWLs most effective. There is an absence of evidence concerning the potential impact of HWLs placed on alcohol products on selection of those products. This study aimed to obtain a preliminary assessment of the possible impact of (a) image-and-text (b) text-only and (c) image-only HWLs on selection of alcoholic versus non-alcoholic drinks. DesignA between-subjects randomised experiment with a 2 (image: present vs absent) x 2 (text: present vs absent) factorial design. SettingThe study was conducted on the online survey platform Qualtrics.Participants Participants (n=6024) were adults over the age of 18 who consumed beer or wine regularly (i.e., at least once a week), recruited through a market research agency. Interventions Participants were randomised to one of four groups varying in the HWL displayed on the packaging of alcoholic drinks: i. image-and-text HWL; ii. text-only HWL; iii. image-only HWL; iv. no HWL. HWLs depicted bowel cancer, breast cancer and liver cancer, which were each displayed twice across six alcoholic drinks. Each group viewed six alcoholic and six non-alcoholic drinks and selected one drink that they would like to consume. MeasurementsThe primary outcome was the proportion of participants selecting an alcoholic versus a non-alcoholic drink.FindingsAlcoholic drink selection was lower for all HWL types compared with no HWL (image-and-text: 56%; image-only: 49%; text-only: 61%; no HWL: 77%), with selection lowest for HWLs that included an image. Image-and-text HWLs reduced the odds of selecting an alcoholic drink compared with text-only HWLs (OR = 0.80, 95% CI = 0.69, 0.92), but increased the odds of selecting an alcoholic drink compared with image-only HWLs (OR = 1.34, 95% CI = 1.16, 1.55).ConclusionsHealth warning labels communicating the increased risk of cancers associated with alcohol consumption reduced selection of alcoholic versus non-alcoholic drinks in a hypothetical choice task in an online setting; labels displaying images had the largest effect. Their impact in laboratory and real-world field settings using physical products awaits investigatio

Large time behavior and asymptotic stability of the two-dimensional Euler and linearized Euler equations

We study the asymptotic behavior and the asymptotic stability of the two-dimensional Euler equations and of the two-dimensional linearized Euler equations close to parallel flows. We focus on spectrally stable jet profiles $U(y)$ with stationary streamlines $y_{0}$ such that $U'(y_{0})=0$, a case that has not been studied previously. We describe a new dynamical phenomenon: the depletion of the vorticity at the stationary streamlines. An unexpected consequence, is that the velocity decays for large times with power laws, similarly to what happens in the case of the Orr mechanism for base flows without stationary streamlines. The asymptotic behaviors of velocity and the asymptotic profiles of vorticity are theoretically predicted and compared with direct numerical simulations. We argue on the asymptotic stability of these flow velocities even in the absence of any dissipative mechanisms.Comment: To be published in Physica D, nonlinear phenomena (accepted January 2010

Weak and Electromagnetic Nuclear Decay Signatures for Neutrino Reactions in SuperKamiokande

We suggest the study of events in the SuperKamiokande neutrino data due to charged- and neutral-current neutrino reactions followed by weak and/or electromagnetic decays of struck nuclei and fragments thereof. This study could improve the prospects of obtaining evidence for $\tau$ production from $\nu_\mu \to \nu_\tau$ oscillations and could augment the data sample used to disfavor $\nu_\mu \to \nu_{sterile}$ oscillations.Comment: 7 pages, latex, to appear in Phys. Rev. Let

A randomised controlled trial of the effects of a web-based PSA decision aid, Prosdex. Protocol

Contains fulltext : 51771.pdf ( ) (Open Access)BACKGROUND: Informed decision making is the theoretical basis in the UK for men's decisions about Prostate Specific Antigen (PSA) testing for prostate cancer testing. The aim of this study is to evaluate the effect of a web-based PSA decision-aid, Prosdex, on informed decision making in men. The objective is to assess the effect of Prosdex on six specific outcomes: (i) knowledge of PSA and prostate cancer-related issues - the principal outcome of the study; (ii) attitudes to testing; (iii) decision conflict; (iv) anxiety; (v) intention to undergo PSA testing; (vi) uptake of PSA testing. In addition, a mathematical simulation model of the effects of Prosdex will be developed. METHODS: A randomised controlled trial with four groups: two intervention groups, one viewing Prosdex and the other receiving a paper version of the site; two control groups, the second controlling for the potential Hawthorn effect of the questionnaire used with the first control group. Men between the ages of 50 and 75, who have not previously had a PSA test, will be recruited from General Practitioners (GPs) in Wales, UK. The principal outcome, knowledge, and four other outcome measures - attitudes to testing, decision conflict, anxiety and intention to undergo testing - will be measured with an online questionnaire, used by men in three of the study groups. Six months later, PSA test uptake will be ascertained from GP records; the online questionnaire will then be repeated. These outcomes, and particularly PSA test uptake, will be used to develop a mathematical simulation model, specifically to consider the impact on health service resources

The LBNO long-baseline oscillation sensitivities with two conventional neutrino beams at different baselines

The proposed Long Baseline Neutrino Observatory (LBNO) initially consists of $\sim 20$ kton liquid double phase TPC complemented by a magnetised iron calorimeter, to be installed at the Pyh\"asalmi mine, at a distance of 2300 km from CERN. The conventional neutrino beam is produced by 400 GeV protons accelerated at the SPS accelerator delivering 700 kW of power. The long baseline provides a unique opportunity to study neutrino flavour oscillations over their 1st and 2nd oscillation maxima exploring the $L/E$ behaviour, and distinguishing effects arising from $\delta_{CP}$ and matter. In this paper we show how this comprehensive physics case can be further enhanced and complemented if a neutrino beam produced at the Protvino IHEP accelerator complex, at a distance of 1160 km, and with modest power of 450 kW is aimed towards the same far detectors. We show that the coupling of two independent sub-MW conventional neutrino and antineutrino beams at different baselines from CERN and Protvino will allow to measure CP violation in the leptonic sector at a confidence level of at least $3\sigma$ for 50\% of the true values of $\delta_{CP}$ with a 20 kton detector. With a far detector of 70 kton, the combination allows a $3\sigma$ sensitivity for 75\% of the true values of $\delta_{CP}$ after 10 years of running. Running two independent neutrino beams, each at a power below 1 MW, is more within today's state of the art than the long-term operation of a new single high-energy multi-MW facility, which has several technical challenges and will likely require a learning curve.Comment: 21 pages, 12 figure