Shaping electron wave functions in a carbon nanotube with a parallel magnetic field

A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here we demonstrate experimentally and theoretically that in carbon nanotube quantum dots, combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17T) magnetic fields in our experiment the wave functions can be tuned all the way from "half-wave resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape, with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with nontrivial lattice and topology.Comment: 5 figure

Trajectories of childhood body mass index are associated with adolescent sagittal standing posture

Objectives. To identify distinct age-related trajectory classes of body mass index (BMI) z-scores from childhood to adolescence, and to examine the association of these trajectories with measures of standing sagittal spinal alignment at 14 years of age. Methods. Adolescents participating in the Western Australian Pregnancy Cohort (Raine) Study contributed data to the study (n=1 373). Age- and gender-specific z-scores for BMI were obtained from height and weight at the ages of 3, 5, 10 and 14 years. Latent class group analysis was used to identify six distinct trajectory classes of BMI z-score. At the age of 14 years, adolescents were categorised into one of four subgroups of sagittal spinal posture using k-means cluster analysis of photographic measures of lumbar lordosis, thoracic kyphosis and trunk sway. Regression modeling was used to assess the relationship between postural angles and subgroups, and different BMI trajectory classes, adjusting for gender. Results. Six trajectory classes of BMI z-score were estimated: Very Low (4%), Low (24%), Average (34%), Ascending (6%), Moderate High (26%) and Very High (6%). The proportions of postural subgroups at age 14 were; Neutral (29%), Flat (22%), Sway (27%) and Hyperlordotic (22%). BMI trajectory class was strongly associated with postural subgroup, with significantly higher proportions of adolescents in the Very High, High and Ascending BMI trajectory classes displaying a Hyperlordotic or Sway posture than a Neutral posture at age 14. Conclusions. This prospective study provides evidence that childhood obesity, and how it develops, is associated with standing sagittal postural alignment in adolescence

Computational ligand design in enantio- and diastereoselective ynamide [5+2] cycloisomerization.

Transition metals can catalyse the stereoselective synthesis of cyclic organic molecules in a highly atom-efficient process called cycloisomerization. Many diastereoselective (substrate stereocontrol), and enantioselective (catalyst stereocontrol) cycloisomerizations have been developed. However, asymmetric cycloisomerizations where a chiral catalyst specifies the stereochemical outcome of the cyclization of a single enantiomer substrate-regardless of its inherent preference-are unknown. Here we show how a combined theoretical and experimental approach enables the design of a highly reactive rhodium catalyst for the stereoselective cycloisomerization of ynamide-vinylcyclopropanes to [5.3.0]-azabicycles. We first establish highly diastereoselective cycloisomerizations using an achiral catalyst, and then explore phosphoramidite-complexed rhodium catalysts in the enantioselective variant, where theoretical investigations uncover an unexpected reaction pathway in which the electronic structure of the phosphoramidite dramatically influences reaction rate and enantioselectivity. A marked enhancement of both is observed using the optimal theory-designed ligand, which enables double stereodifferentiating cycloisomerizations in both matched and mismatched catalyst-substrate settings

Uptake and factors that influence the use of ‘sit less, move more’ occupational intervention strategies in Spanish office employees

Background Little is known about the types of ‘sit less, move more’ strategies that appeal to office employees, or what factors influence their use. This study assessed the uptake of strategies in Spanish university office employees engaged in an intervention, and those factors that enabled or limited strategy uptake. Methods The study used a mixed method design. Semi-structured interviews were conducted with academics and administrators (n = 12; 44 ± 12 mean SD age; 6 women) at three points across the five-month intervention, and data used to identify factors that influenced the uptake of strategies. Employees who finished the intervention then completed a survey rating (n = 88; 42 ± 8 mean SD age; 51 women) the extent to which strategies were used [never (1) to usually (4)]; additional survey items (generated from interviewee data) rated the impact of factors that enabled or limited strategy uptake [no influence (1) to very strong influence (4)]. Survey score distributions and averages were calculated and findings triangulated with interview data. Results Relative to baseline, 67% of the sample increased step counts post intervention (n = 59); 60% decreased occupational sitting (n = 53). ‘Active work tasks’ and ‘increases in walking intensity’ were the strategies most frequently used by employees (89% and 94% sometimes or usually utilised these strategies); ‘walk-talk meetings’ and ‘lunchtime walking groups’ were the least used (80% and 96% hardly ever or never utilised these strategies). ‘Sitting time and step count logging’ was the most important enabler of behaviour change (mean survey score of 3.1 ± 0.8); interviewees highlighted the motivational value of being able to view logged data through visual graphics in a dedicated website, and gain feedback on progress against set goals. ‘Screen based work’ (mean survey score of 3.2 ± 0.8) was the most significant barrier limiting the uptake of strategies. Inherent time pressures and cultural norms that dictated sedentary work practices limited the adoption of ‘walk-talk meetings’ and ‘lunch time walking groups’. Conclusions The findings provide practical insights into which strategies and influences practitioners need to target to maximise the impact of ‘sit less, move more’ occupational intervention strategies

Inflammatory myofibroblastic tumour of the gallbladder

BACKGROUND: Inflammatory myofibroblastic tumour (IMT) is a benign, nonmetastasizing proliferation of myofibroblasts with a potential for local infiltration, recurrence and persistent local growth. CASE REPORT: We report a case of a 51 year-old female, who had excision of a gallbladder tumour. Histopathology showed it to be IMT of the gallbladder. CONCLUSION: The approach to these tumours should be primarily surgical resection to obtain a definitive diagnosis and relieve symptoms. IMT has a potential for local infiltration, recurrence and persistent local growth

Socio-demographic, behavioural and cognitive correlates of work-related sitting time in German men and women

Background: Sitting time is ubiquitous for most adults in developed countries and is most prevalent in three domains: in the workplace, during transport and during leisure time. The correlates of prolonged sitting time in workplace settings are not well understood. Therefore, the aim of this study was to examine the gender-specific associations between the socio-demographic, behavioural and cognitive correlates of work-related sitting time. Methods: A cross-sectional sample of working German adults (n = 1515; 747 men; 43.5 ± 11.0 years) completed questionnaires regarding domain-specific sitting times and physical activity (PA) and answered statements concerning beliefs about sitting. To identify gender-specific correlates of work-related sitting time, we used a series of linear regressions. Results The overall median was 2 hours of work-related sitting time/day. Regression analyses showed for men (β = -.43) and for women (β = -.32) that work-related PA was negatively associated with work-related sitting time, but leisure-related PA was not a significant correlate. For women only, transport-related PA (β = -.07) was a negative correlate of work-related sitting time, suggesting increased sitting times during work with decreased PA in transport. Education and income levels were positively associated, and in women only, age (β = -.14) had a negative correlation with work-related sitting time. For both genders, TV-related sitting time was negatively associated with work-related sitting time. The only association with cognitive correlates was found in men for the belief ‘Sitting for long periods does not matter to me’ (β = .10) expressing a more positive attitude towards sitting with increasing sitting durations. Conclusions: The present findings show that in particular, higher educated men and women as well as young women are high-risk groups to target for reducing prolonged work-related sitting time. In addition, our findings propose considering increasing transport-related PA, especially in women, as well as promoting recreation-related PA in conjunction with efforts to reduce long work-related sitting times

Evaluating short-term musculoskeletal pain changes in desk-based workers receiving a workplace sitting-reduction intervention

This paper explores changes in musculoskeletal pain among desk-based workers over three months of a workplace-delivered, sitting-reduction intervention. Participants (n = 153, 46% female; mean ± SD aged 38.9 ± 8.0 years) were cluster-randomized (n = 18 work teams) to receive an organizational change intervention, with or without an activity tracker. A modified Nordic Musculoskeletal Questionnaire assessed pain intensity (0–9; none–worst possible) in the neck, upper and lower back, upper and lower extremities, and in total. The activPAL3 (7 days, 24 h/day protocol) measured sitting and prolonged sitting in =30 min bouts at work. Mixed models adjusting for cluster and intervention arm examined changes in pain (n = 104), and their associations with reductions in sitting and prolonged sitting (h/10 h at work) (n = 90). Changes in pain were nonsignificant (p = 0.05) and small for total pain (-0.06 [95% CI: -0.27, 0.16]) and for each body area (-0.26 [-0.66, 0.15] for upper back to 0.09 [-0.39, 0.56] for lower back). Sitting reduction was associated with reduced lower back pain (-0.84 [-1.44, -0.25] per hour, p = 0.005); other effects were small and non-significant. No substantial average changes in pain were seen; some improvement in lower back pain might be expected with larger sitting reductions. Larger samples and diverse interventions are required for more definitive evidence

The Virtual-Spine Platform—Acquiring, visualizing, and analyzing individual sitting behavior

Back pain is a serious medical problem especially for those people sitting over long periods during their daily work. Here we present a system to help users monitoring and examining their sitting behavior. The Virtual-Spine Platform (VSP) is an integrated system consisting of a real-time body position monitoring module and a data visualization module to provide individualized, immediate, and accurate sitting behavior support. It provides a comprehensive spine movement analysis as well as accumulated data visualization to demonstrate behavior patterns within a certain period. The two modules are discussed in detail focusing on the design of the VSP system with adequate capacity for continuous monitoring and a web-based interactive data analysis method to visualize and compare the sitting behavior of different persons. The data was collected in an experiment with a small group of subjects. Using this method, the behavior of five subjects was evaluated over a working day, enabling inferences and suggestions for sitting improvements. The results from the accumulated data module were used to elucidate the basic function of body position recognition of the VSP. Finally, an expert user study was conducted to evaluate VSP and support future developments

Australia and Other Nations are Failing to Meet Sedentary Behaviour Guidelines for Children: Implications and a Way Forward

BACKGROUND: Australia has joined a growing number of nations which have evaluated the physical activity and sedentary behaviour status of their children. Australia received a 'D minus' in the first Active Healthy Kids Australia Physical Activity Report Card. METHODS: An expert subgroup of the Australian Report Card Research Working Group iteratively reviewed available evidence to answer three questions: 1) What are the main sedentary behaviours of children?, 2) What are the potential mechanisms for sedentary behaviour to impact on child health and development? and, 3) What are the effects of different types of sedentary behaviours on child health and development? RESULTS: Neither sedentary time nor screen time are homogeneous activities likely to result in homogenous effects. There are several mechanisms by which various sedentary behaviours may positively or negatively affect cardiometabolic, neuro-musculoskeletal, and psycho-social health, though the strength of evidence varies. National surveillance systems, and mechanistic, longitudinal and experimental studies are needed for Australia and other nations to improve their grade. CONCLUSIONS: Despite limitations, available evidence is sufficiently convincing that the total exposure and pattern of exposure to sedentary behaviours are critical to the healthy growth, development and wellbeing of children. Nations therefore need strategies to address these common behaviours