Anderson Localization in Disordered Vibrating Rods

We study, both experimentally and numerically, the Anderson localization phenomenon in torsional waves of a disordered elastic rod, which consists of a cylinder with randomly spaced notches. We find that the normal-mode wave amplitudes are exponentially localized as occurs in disordered solids. The localization length is measured using these wave amplitudes and it is shown to decrease as a function of frequency. The normal-mode spectrum is also measured as well as computed, so its level statistics can be analyzed. Fitting the nearest-neighbor spacing distribution a level repulsion parameter is defined that also varies with frequency. The localization length can then be expressed as a function of the repulsion parameter. There exists a range in which the localization length is a linear function of the repulsion parameter, which is consistent with Random Matrix Theory. However, at low values of the repulsion parameter the linear dependence does not hold.Comment: 10 pages, 6 figure

Anderson Localization Phenomenon in One-dimensional Elastic Systems

The phenomenon of Anderson localization of waves in elastic systems is studied. We analyze this phenomenon in two different set of systems: disordered linear chains of harmonic oscillators and disordered rods which oscillate with torsional waves. The first set is analyzed numerically whereas the second one is studied both experimentally and theoretically. In particular, we discuss the localization properties of the waves as a function of the frequency. In doing that we have used the inverse participation ratio, which is related to the localization length. We find that the normal modes localize exponentially according to Anderson theory. In the elastic systems, the localization length decreases with frequency. This behavior is in contrast with what happens in analogous quantum mechanical systems, for which the localization length grows with energy. This difference is explained by means of the properties of the re ection coefficient of a single scatterer in each case.Comment: 15 pages, 10 figure

Wannier-Stark ladders in one-dimensional elastic systems

The optical analogues of Bloch oscillations and their associated Wannier-Stark ladders have been recently analyzed. In this paper we propose an elastic realization of these ladders, employing for this purpose the torsional vibrations of specially designed one-dimensional elastic systems. We have measured, for the first time, the ladder wave amplitudes, which are not directly accessible either in the quantum mechanical or optical cases. The wave amplitudes are spatially localized and coincide rather well with theoretically predicted amplitudes. The rods we analyze can be used to localize different frequencies in different parts of the elastic systems and viceversa.Comment: 10 pages, 6 figures, accepted in Phys. Rev. Let

Persistent financial hardship, 11-year weight gain, and health behaviors in the Whitehall II study.

OBJECTIVE: To ascertain prospectively gender-specific associations between types and amounts of financial hardship and weight gain, and investigate potential behavioral mechanisms. METHODS: Prospective study of 3701 adult British civil servants with repeated measures of difficulty paying bills or insufficient money to afford adequate for food/clothing (1985-1988; 1989-1990; 1991-1993; 1997-1999), and weight (1985-1988; 1997-1999). RESULTS: Persistent hardships were associated with adjusted mean weight change in women over 10.9 years, but no consistent pattern was seen in men. During follow-up, 46% of women gained ≥5 kg. Women reporting persistent insufficient money for food/clothing had a significantly greater odds of gaining ≥5 kg (1.42 [1.05, 1.92]) compared to no hardship history, which remained after socioeconomic status (SES) adjustment (1.45 [1.05, 2.01]). The association between persistent difficulty paying bills and odds of excess weight gain was also significant (1.42 [1.03, 1.97]) but attenuated after considering SES (1.39 [0.98, 1.97]). Four health behaviors as single measures or change variables did not attenuate associations. CONCLUSIONS: Results suggested strategies to tackle obesity must address employed women's everyday financial troubles which may influence weight through more biological pathways than classical correlates of economic disadvantage and weight.This is the final version, originally published in the journal Obesity here: http://onlinelibrary.wiley.com/doi/10.1002/oby.20875/abstract;jsessionid=EDA4F761217B492D16E7384EB67A7399.f02t02

Job-loss and weight gain in British adults: Evidence from two longitudinal studies.

Overweight and obesity have been associated with unemployment but less is known about changes in weight associated with changes in employment. We examined weight changes associated with job-loss, retirement and maintaining employment in two samples of working adults in the United Kingdom. This was a prospective study of 7201 adults in the European Prospective Investigation of Cancer (EPIC)-Norfolk study (aged 39-76 years) and 4539 adults in the British Household Panel Survey (BHPS) who were followed up over 43 months and 26 months, respectively. In both samples, changes in measured (EPIC) and self-reported (BHPS) weight were computed for each participant and assessed in relation to three employment transitions: maintaining paid employment, retirement and job-loss. Regression models adjusted for potential confounders. Further analyses evaluated the contribution of diet, physical activity and smoking to weight gain. In EPIC-Norfolk, weight change differed across the three employment transitions for women but not men. The mean (95% CI) annualised change in weight for women who became unemployed over the follow-up period was 0.70 (0.55, 0.85) kg/y while those who maintained employment gained 0.49 (0.43, 0.55) kg/y (P = 0.007). Accounting for changes in smoking, diet and physical activity did not substantially alter the difference in weight gain among groups. In BHPS, job-loss was associated with weight gain of 1.56 (0.89, 2.23) kg/y, while those who maintained employment 0.60 (0.53, 0.68) kg/y (P < 0.001). In both samples, weight changes associated with retirement were similar to those staying in work. In BHPS, job-loss was also associated with significant declines in self-reported well-being and increases in sleep-loss. Two UK-based samples of working adults reveal strong associations between job-loss and excess weight gain. The mediating behaviours are so far unclear but psychosocial mechanisms and sleep-loss may contribute to the excess weight gain among individuals who become unemployed.This work was undertaken by the Centre for Diet and Activity Research, a UK Clinical Research Collaboration Public Health Research Centre of Excellence. Funding from the British Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, National Institute for Health Research, and Wellcome Trust, under the auspices of the UK Clinical Research Collaboration, is gratefully acknowledged

Gender and the double burden of economic and social disadvantages on healthy eating: cross-sectional study of older adults in the EPIC-Norfolk cohort

Abstract Background Multiple economic factors and social relationships determine dietary behaviours, but the inter-relations between determinants is unknown. Whether women and men differ in the vulnerability to, and impact of, combined disadvantages is also unclear. We examined associations between diverse combinations of economic resources and social relationships, and healthy eating in British older women and men. Methods Our sample comprised 9,580 over-50s (47 % of over-50 respondents) in the EPIC-Norfolk cohort study. We examined six economic factors (education, social class, home-ownership, money for needs, frequency of insufficient money for food/clothing, paying bills) and three social relationships (marital status, living arrangement and friend contact), independently and in combination, in relation to fruit variety and vegetable variety. We analysed gender-specific associations using multivariable linear regression with interaction terms. Results Lower social class, lower education, and difficulty paying bills were associated with lower fruit and vegetable variety in both genders, independent of social relationships. All social relationships were independently associated with fruit variety in men and with vegetable variety in both genders. Substantially lower variety was found for all combinations of low economic resources and lack of social relationship than for either measure alone, with men faring worse in the majority of combined disadvantages. For example, the difference in vegetable variety for men reporting low social class and non-married was much greater (β -4.1, [-4.8, -3.4]), than the independent association of low social class (β -1.5, [-1.8,–1.2]), or non-married (β -1.8, [-2.3,–1.3]). Variety was also lower among men with high economic resources but non-married or lone-living. Conclusion A double burden of low economic resources and lack of social relationships suggested they are unique joint determinants, particularly in older men, and that public health efforts to improve healthy eating would offer most benefit to older adults with intersecting economic and social disadvantages

Associations between exposure to takeaway food outlets, takeaway food consumption, and body weight in Cambridgeshire, UK: population based, cross sectional study.

OBJECTIVES: To examine the association between environmental exposure to takeaway food outlets, takeaway food consumption, and body weight, while accounting for home, work place, and commuting route environments. DESIGN: Population based, cross sectional study, using data on individual participants' diet and weight, and objective metrics of food environment exposure. PARTICIPANTS: Working adults participating in the Fenland Study, Cambridgeshire, UK (n = 5442, aged 29-62 years), who provided home and work addresses and commuting preferences. Takeaway food outlet exposure was derived using data from local authorities for individual environmental domains (at home, at work, and along commuting routes (the shortest route between home and work)), and for exposure in all three domains combined. Exposure was divided into quarters (Q); Q1 being the least exposed and Q4 being the most exposed. MAIN OUTCOME MEASURES: Self reported consumption of takeaway type food (g/day; pizza, burgers, fried foods, and chips) using food frequency questionnaires, measured body mass index, and cut-offs for body mass index as defined by the World Health Organization. RESULTS: In multiple linear regression models, exposure to takeaway food outlets was positively associated with consumption of takeaway food. Among domains at home, at work, and along commuting routes, associations were strongest in work environments (Q4 v Q1; β coefficient = 5.3 g/day, 95% confidence interval 1.6 to 8.7; P<0.05), with evidence of a dose-response effect. Associations between exposure in all three domains combined and consumption were greater in magnitude across quarters of exposure (Q4 v Q1; 5.7 g/day, 2.6 to 8.8; P<0.001), with evidence of a dose-response effect. Combined exposure was especially strongly associated with increased body mass index (Q4 v Q1; body mass index 1.21, 0.68 to 1.74; P<0.001) and odds of obesity (Q4 v Q1; odds ratio 1.80, 1.28 to 2.53; P<0.05). There was no evidence of effect modification by sex. CONCLUSIONS: Exposure to takeaway food outlets in home, work, and commuting environments combined was associated with marginally higher consumption of takeaway food, greater body mass index, and greater odds of obesity. Government strategies to promote healthier diets through planning restrictions for takeaway food could be most effective if focused around the workplace

Accordance to the Dietary Approaches to Stop Hypertension diet pattern and cardiovascular disease in a British, population-based cohort.

The dietary approaches to stop hypertension (DASH) diet could be an important population-level strategy to reduce cardiovascular disease (CVD) in the UK, but there is little UK-based evidence on this diet pattern in relation to CVD risk. We tested whether dietary accordance with DASH was associated with risk of CVD in a population-based sample of 23,655 UK adults. This prospective analysis of the EPIC-Norfolk cohort study analysed dietary intake (assessed using a validated food frequency questionnaire) to measure accordance with DASH, based on intakes of eight food groups and nutrients, ranking the sample into quintiles. Cox proportional hazards regression models tested for association between DASH accordance and incident stroke, ischemic heart disease (IHD) and total incident CVD (stroke and IHD only), as well as CVD mortality, non-CVD mortality and total mortality. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated adjusting for age, sex, behavioral and clinical risk factors and socioeconomic status. Over an average of 12.4 years follow-up, we ascertained 4129 incident CVD events, of which stroke accounted for 1011. Compared to participants with the least DASH-accordant diets, those with the most DASH-accordant diets had 20% lower risk of incident stroke (HR, 95% CI 0.80, 0.65-0.99) and 13% lower risk of total incident CVD (0.88, 0.79-0.99) but no lower risk of CHD (0.90, 0.79-1.02). CVD-related mortality also showed strong inverse associations with DASH accordance (0.72, 0.60-0.85). This study provides evidence for the cardioprotective effects of DASH diet in a UK context

Variety more than quantity of fruit and vegetable intake varies by socioeconomic status and financial hardship. Findings from older adults in the EPIC cohort.

BACKGROUND: Beyond quantity, variety of fruit and vegetable (FV) intake prevents chronic conditions and is widely recommended as critical to healthful eating. FV consumption is socially patterned, especially for women, but little is known about multiple economic determinants of variety or whether they differ from those of quantity. OBJECTIVE: To examine socioeconomic status and financial hardships in relation to variety and quantity of FV intakes among older British women and men. METHODS: Cross-sectional study of 9580 adults (50-79 years) in the nationally representative EPIC cohort who responded to a postal Health and Life Experiences Questionnaire (1996-2000) and Food Frequency Questionnaire (1998-2002). Variety counted unique items consumed (items/month) and quantity measured total intake (g/day). RESULTS: No consistent differences by any economic factor were observed for quantity of fruits or vegetables, except education in men. Lower education, lower social class and renting were independently associated with lower fruit variety and vegetable variety (p-trend < 0.001), with differences stronger in men. Mean vegetable variety differed between top and bottom social classes by 2.9 items/month for men and 2.5 for women. Greater financial hardships were also independently associated with lower variety, with differences stronger in women for fruits and in men for vegetables. CONCLUSIONS: British older adults reporting greater economic disadvantage consistently consumed fewer different fruits or vegetables, but not lower amounts. Further nutrition studies of the protective effects, and underlying mechanisms, of FV variety are warranted for addressing social inequalities in older adults' diet quality. Dietary guidance should separately emphasise variety, and interventions should aim to address financial barriers to older adults' consumption of diverse FV.We thank the Gates Cambridge Trust for full PhD funding. Authors supported the Centre for Diet and Activity Research (CEDAR), a UKCRC Public Health Research of Excellence, acknowledge funding by: the British Heart Foundation, Economic and Social Research Council, Medical Research Council, National Institute for Health Research and the Wellcome Trust, under the auspices of the UK Clinical Research Collaboration. We acknowledge core MRC Epidemiology Unit support through Programmes MC_UU_12015/1 and MC_UU_12015/5.This is the final version. It was first published by Elsevier in Appetite at http://www.sciencedirect.com/science/article/pii/S0195666314004413

Does the importance of dietary costs for fruit and vegetable intake vary by socioeconomic position?

Evidence suggests that diets meeting recommendations for fruit and vegetable (F&V) intake are more costly. Dietary costs may be a greater constraint on the diet quality of people of lower socioeconomic position (SEP). The aim of this study was to examine whether dietary costs are more strongly associated with F&V intake in lower-SEP groups than in higher-SEP groups. Data on individual participants' education and income were available from a population-based, cross-sectional study of 10 020 British adults. F&V intake and dietary costs (GBP/d) were derived from a semi-quantitative FFQ. Dietary cost estimates were based on UK food prices. General linear models were used to assess associations between SEP, quartiles of dietary costs and F&V intake. Effect modification of SEP gradients by dietary costs was examined with interaction terms. Analysis demonstrated that individuals with lowest quartile dietary costs, low income and low education consumed less F&V than individuals with higher dietary costs, high income and high education. Significant interaction between SEP and dietary costs indicated that the association between dietary costs and F&V intake was stronger for less-educated and lower-income groups. That is, socioeconomic differences in F&V intake were magnified among individuals who consumed lowest-cost diets. Such amplification of socioeconomic inequalities in diet among those consuming low-cost diets indicates the need to address food costs in strategies to promote healthy diets. In addition, the absence of socioeconomic inequalities for individuals with high dietary costs suggests that high dietary costs can compensate for lack of other material, or psychosocial resources.This work was undertaken by the Centre for Diet and Activity Research, a UK Clinical Research Collaboration Public Health Research Centre of Excellence. Funding from the British Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, National Institute for Health Research, and Wellcome Trust, under the auspices of the UK Clinical Research Collaboration, is gratefully acknowledged. Core MRC Epidemiology Unit support through programmes MC_UU_12015/1 and MC_UU_12015/5 is acknowledged. Funders had no role in the design, conduct, analysis, interpretation or publication of the manuscript.This is the final version of the article. It first appeared from Cambridge University Press via http://dx.doi.org/10.1017/S000711451500302