Environmental invitingness for transport-related cycling in middle-aged adults: a proof of concept study using photographs

Introduction: Current evidence on associations between modifiable environmental characteristics and transport-related cycling remains inconsistent. Most studies on these associations used questionnaires to determine environmental perceptions, but such tools may be subject to bias due to unreliable recall. Moreover, questionnaires only measure separate environmental characteristics, while real environments are a combination of different characteristics. To overcome these limitations, the present proof of concept study used panoramic photographs of cycling environments to capture direct responses to the physical environment. We examined which depicted environmental characteristics were associated to environments' invitingness for transportation cycling. Furthermore, interactions with gender and participants' cycling behavior were examined. Methods: Fifty-nine middle-aged adults were recruited through purposeful convenience sampling. During a home visit, participants took part in a structured interview assessing demographics and PA during the preceding seven days, followed by an intuitive choice task and a (cognitive) rating task, which both measured 40 photographed environments' invitingness to cycle along. Multi-level cross-classified analyses were conducted using MLwiN 2.26. Results: Both tasks' multivariate results showed that presence of vegetation was identified as the most important environmental characteristic to invite people for engaging in transportation cycling, even when the amount of vegetation was relatively small. In the bivariate analyzes, some differences between results of the cognitive rating task and the intuitive choice task were found, showing that invitingness measured by the rating task was associated with environmental maintenance and cycling infrastructure, whereas invitingness determined by the choice task was associated with more traffic-oriented characteristics. Moreover, only for the choice task's results, moderating effects of gender and participants' cycling behavior in the preceding week were observed. Conclusion: The present study provides proof of concept that capturing people's less cognitive, more intuitive responses to an environment's invitingness for transport-related cycling may be important for revealing environment-behavior associations. If replicated in future studies using larger samples, results of our innovative measurements with photographs, especially those on vegetation, can complete the existing knowledge on which environmental characteristics are important for transportation cycling in adults and could form a basis to inform health promoters and local policy makers. However, future studies replicating our study method in larger samples and other population subgroups are highly encouraged. Moreover, causal relationships should be explored.

Continuous finite-time state feedback stabilizers for some nonlinear stochastic systems

This paper is concerned with the problem of finite-time stabilization for some nonlinear stochastic systems. Based on the stochastic Lyapunov theorem on finite-time stability that has been established by the authors in the paper, it is proven that Euler-type stochastic nonlinear systems can be finite-time stabilized via a family of continuous feedback controllers. Using the technique of adding a power integrator, a continuous, global state feedback controller is constructed to stabilize in finite time a large class of two-dimensional lower-triangular stochastic nonlinear systems. Also, for a class of three-dimensional lower-triangular stochastic nonlinear systems, a recursive design scheme of finite-time stabilization is given by developing the technique of adding a power integrator and constructing a continuous feedback controller. Finally, a simulation example is given to illustrate the theoretical results. © 2014 John Wiley & Sons, Ltd.

A novel fuzzy multi-objective framework to construct optimal prediction intervals for wind power forecast

The forecasting behavior of the high volatile and unpredictable wind power energy has always been a challenging issue in the power engineering area. In this regard, this paper proposes a new multi-objective framework based on fuzzy idea to construct optimal prediction intervals (Pis) to forecast wind power generation more sufficiently. The proposed method makes it possible to satisfy both the PI coverage probability (PICP) and PI normalized average width (PINAW), simultaneously. In order to model the stochastic and nonlinear behavior of the wind power samples, the idea of lower upper bound estimation (LUBE) method is used here. Regarding the optimization tool, an improved version of particle swam optimization (PSO) is proposed. In order to see the feasibility and satisfying performance of the proposed method, the practical data of a wind farm in Australia is used as the case study.

Assessing cycling-friendly environments for children: are micro-environmental factors equally important across different street settings?

BACKGROUND: As physical activity levels decrease as children age, sustainable and accessible forms of physical activity are needed from a young age. Transportation cycling is one such physical activity and has been associated with many benefits. The aims of the study were to identify whether manipulating micro-environmental factors (e.g. speed limis, evenness of cycle path) within a photographed street influences the perceived supportiveness for transportation cycling; and whether changing these micro-environmental factors has the same effect across different street settings. METHODS: We recruited 305 fifth and sixth grade children and their parents from twelve randomly selected primary schools in Flanders, Belgium. They completed a web-based questionnaire including 12 choice-based conjoint tasks, in which they had to choose between two possible routes depicted on manipulated photographs, which the child would cycle along. The routes differed in four attributes: general street setting (enclosed, half open, open), evenness of cycle path (very uneven, moderately uneven, even), speed limit (70 km/h, 50 km/h, 30 km/h) and degree of separation between a cycle path and motorised traffic (no separation, curb, hedge). Hierarchical Bayes analyses revealed the relative importance of each micro-environmental attribute across the three street settings. RESULTS: For each attribute, children and their parents chose routes that had the best alternative (i.e. open street setting, even cycle path, 30 km/h, a hedge separating the cycle path from motorised traffic). The evenness of the cycle path and lower speed limit had the largest effect for the children, while the degree of separation and lower speed limit had the largest effect for their parents. Interactions between micro-scale and macro-scale factors revealed differences in the magnitude but not direction of their effects on route choice. The results held across the different kinds of street settings tested. CONCLUSIONS: Improving micro-scale attributes may increase the supportiveness of a street for children's transportation cycling. We call for on-site research to test effects of changes in micro-environmental attributes on transportation cycling among children.

The effect of low cycle fatigue, ratcheting and mean stress relaxation on stress-strain response and microstructural development in a dual phase steel

This study examines the cyclic plastic deformation behavior and microstructural development of a dual phase steel in both symmetric and asymmetric cycling in strain and stress control modes. The low-cycle fatigue (LCF) and mean stress relaxation (MSR) tests show very similar fatigue lifetimes. However, fatigue lifetimes reduce and prominent accumulation of directional strain was observed in ratcheting. A microstructural analysis has revealed that the type of cyclic test carried out has a noticeable impact on the substructural development, and this has been correlated with differences in accumulated tensile strain. Electron backscatter diffraction investigation has shown larger in-grain misorientation for ratcheting specimen in comparison with LCF and MSR specimens. The orientation of ferrite grains was found to have very little effect on their substructural development, and strain localization commonly occurred in the ferrite at the ferrite/martensite interface.

Global finite-time stabilisation for a class of stochastic nonlinear systems by output feedback

In this paper, the problem of global finite-time stabilisation by output feedback is considered for a class of stochastic nonlinear systems. First, based on homogeneous systems theory and the adding a power integrator technique, a homogeneous reduced order observer and control law are constructed in a recursive manner for the nominal system. Then, the homogeneous domination approach is used to deal with the nonlinearities in drift and diffusion terms; it is shown that the proposed output-feedback control law can guarantee that the closed-loop system is global finite-time stable in probability. Finally, simulation examples are carried out to demonstrate the effectiveness of the proposed control scheme.

Monitoring neuromuscular fatigue in team-sport athletes using a cycle-ergometer test

PURPOSE: To compare a novel sprint test on a cycle ergometer with a countermovement-jump (CMJ) test for monitoring neuromuscular fatigue after Australian rules football match play. METHODS: Twelve elite under-18 Australian rules football players (mean ± SD age 17.5 ± 0.6 y, stature 184.7 ± 8.8 cm, body mass 75.3 ± 7.8 kg) from an Australian Football League club's Academy program performed a short sprint test on a cycle ergometer along with a single CMJ test 1 h prematch and 1, 24, and 48 h postmatch. The cycle-ergometer sprint test involved a standardized warm-up, a maximal 6-s sprint, a 1-min active recovery, and a 2nd maximal 6-s sprint, with the highest power output of the 2 sprints recorded as peak power (PP). RESULTS: There were small to moderate differences between postmatch changes in cycle-ergometer PP and CMJ PP at 1 (ES = 0.49), 24 (ES = -0.85), and 48 h postmatch (ES = 0.44). There was a substantial reduction in cycle-ergometer PP at 24 h postmatch (ES = -0.40) compared with 1 h prematch. CONCLUSIONS: The cycle-ergometer sprint test described in this study offers a novel method of neuromuscular-fatigue monitoring in team-sport athletes and specifically quantifies the concentric component of the fatigue-induced decrement of force production in muscle, which may be overlooked by a CMJ test.

Exponential stability for markovian jumping stochastic BAM neural networks with mode-dependent probabilistic time-varying delays and impulse control

Abstract
In this article, an exponential stability analysis of Markovian jumping stochastic bidirectional associative memory (BAM) neural networks with mode-dependent probabilistic time-varying delays and impulsive control is investigated. By establishment of a stochastic variable with Bernoulli distribution, the information of probabilistic time-varying delay is considered and transformed into one with deterministic time-varying delay and stochastic parameters. By fully taking the inherent characteristic of such kind of stochastic BAM neural networks into account, a novel Lyapunov-Krasovskii functional is constructed with as many as possible positive definite matrices which depends on the system mode and a triple-integral term is introduced for deriving the delay-dependent stability conditions. Furthermore, mode-dependent mean square exponential stability criteria are derived by constructing a new Lyapunov-Krasovskii functional with modes in the integral terms and using some stochastic analysis techniques. The criteria are formulated in terms of a set of linear matrix inequalities, which can be checked efficiently by use of some standard numerical packages. Finally, numerical examples and its simulations are given to demonstrate the usefulness and effectiveness of the proposed results.

Creating cycling-friendly environments for children: which micro-scale factors are most important? An experimental study using manipulated photographs

BACKGROUND: Increasing participation in transportation cycling represents a useful strategy for increasing children's physical activity levels. Knowledge on how to design environments to encourage adoption and maintenance of transportation cycling is limited and relies mainly on observational studies. The current study experimentally investigates the relative importance of micro-scale environmental factors for children's transportation cycling, as these micro-scale factors are easier to change within an existing neighborhood compared to macro-scale environmental factors (i.e. connectivity, land-use mix, …). METHODS: Researchers recruited children and their parents (n = 1232) via 45 randomly selected schools across Flanders and completed an online questionnaire which consisted of 1) demographic questions; and 2) a choice-based conjoint (CBC) task. During this task, participants chose between two photographs which we had experimentally manipulated in seven micro-scale environmental factors: type of cycle path; evenness of cycle path; traffic speed; traffic density; presence of speed bumps; environmental maintenance; and vegetation. Participants indicated which route they preferred to (let their child) cycle along. To find the relative importance of these micro-scale environmental factors, we conducted Hierarchical Bayes analyses. RESULTS: Type of cycle path emerged as the most important factor by far among both children and their parents, followed by traffic density and maintenance, and evenness of the cycle path among children. Among parents, speed limits and maintenance emerged as second most important, followed by evenness of the cycle path, and traffic density. CONCLUSION: Findings indicate that improvements in micro-scale environmental factors might be effective for increasing children's transportation cycling, since they increase the perceived supportiveness of the physical environment for transportation cycling. Investments in creating a clearly designated space for the young cyclist, separated from motorized traffic, appears to be the most effective way to increase perceived supportiveness. Future research should confirm our laboratory findings with experimental on-site research.

Influence of pacing on reliability of middle-distance cycling performance

The purpose of the present study was to examine the reliability of middle distance cycling time trials using fast-, even-, and slow-starts. Eighteen endurance-trained male cyclists [mean ± standard deviation; VO2peak 63.1 ± 6.1 mL⋅kg-1⋅min-1] performed nine cycling time trials where the total external work (96.5 ± 11.2 kJ) was identical to the better of two, 5-minute habituation time trials. Power output during the first quarter of the time-trials (24.1 ± 2.8 kJ) was fixed to induce fast-, even- or slow-starting strategies (60, 75 and 90 s, respectively). In consecutive sessions, participants performed three trials of each pacing condition although the order of these pacing conditions was counterbalanced. Average power output and performance time were unaffected by trial number in the fast- (P = 0.60), even- (P = 0.18) and slow-start (P = 0.53) trials. In all three pacing conditions, average power output was highly reliable and similar between trial 1 to 2 and trial 2 to 3 in fast- (standard error of measurement; SEM=8.3 and 8.2W), even (coefficient of variation; CV=2.8 and 2.4%) and slow-start (CV=2.4 and 1.5%) trials. In conclusion, the reproducibility of 5-min cycling time trials is unaffected by starting strategy and is acceptable following two selfpaced habituation trials. Research examining the influence of pacing strategies may therefore be conducted without the need for familiarisation trials using each individual pacing condition.

Metabolic power method underestimates energy expenditure in field sport movements using a GPS tracking system

The purpose of this study was to assess the validity of a GPS tracking system to estimate energy expenditure (EE) during exercise and field sport locomotor movements. Twenty-seven participants each completed one 90 minute exercise session on an outdoor synthetic futsal pitch. During the exercise session participants wore a 5 Hz GPS unit interpolated to 15 Hz (SPI HPU, GPSports Pty Ltd, Australia) and a portable gas analyser (Metamax® 3B, Cortex Pty Ltd, Germany) which acted as the criterion measure of EE. The exercise session was comprised of alternating five minute exercise bouts of randomised walking, jogging, running or a field sport circuit (x3) followed by 10 minutes of recovery. One-way ANOVA showed significant (p<0.01) and very large underestimations between GPS metabolic power derived EE and VO2 derived EE for all field sport circuits (% difference ≈ -44%). No differences in EE were observed for the jog (7.8%) and run (4.8%) while very large overestimations were found for the walk (43.0%). The GPS metabolic power EE over the entire 90 minute session was significantly lower (p<0.01) than the VO2 EE, resulting in a moderate underestimation overall (-19%). The results of this study suggest that a GPS tracking system using the metabolic power model of EE does not accurately estimate EE in field sport movements or over an exercise session consisting of mixed locomotor activities interspersed with recovery periods; however is able to provide a reasonably accurate estimation of EE during continuous jogging and running.

Mudanças institucionais, receitas cumulativas do governo federal e exportações no Brasil entre 1982 e 2001

Desde o início dos anos oitenta, o governo federal brasileiro passou a substituir a receitas de impostos tradicionais por receita de contribuições sociais (cumulativas) na composição da sua receita total (mudança de gestão). Alega-se que este procedimento é uma conseqüência das regras de compartilhamento estabelecidas (receitas de impostos do governo federal são compartilhadas com estados e municípios enquanto que receitas de contribuição não o são).Existem argumentos na literatura mostrando que este processo de descentralização das receitas teve sua origem na mudança de regime político (militar para democrático), outros com a nova Constituição de 1988 e, por último, outros afirmando que ele só foi possível porque a ineficiência das contribuições foi encoberta pela ineficiência alocativa da inflação. Por outro lado, fatos ocorridos no mesmo período, embora não citados na literatura, poderiam explicar ou ajudar na explicação deste comportamento. Entre eles, a fragmentação do poder executivo a partir de 1989 com a primeira eleição presidencial e/ou o processo de abertura da economia a partir dos anos noventa. Usando a técnica de OLS, observou-se que a Nova Constituição e a abertura da economia explicariam esta mudança de gestão. De qualquer forma, independente do que esteja explicando esta mudança, ela é apontada como altamente prejudicial a competitividade das exportações brasileiras. Existem várias proxies tentando medir este efeito, nenhuma delas considerando uma medida de gestão. Resolvemos realizar esta tentativa. Como tínhamos desconfiança da exogeneidade da variável representativa da abertura da economia no teste anterior, tratamos a questão com o instrumental de séries de tempo. No longo prazo, descobrimos que a mudança de gestão afeta negativamente as exportações e positivamente a abertura da economia por ser menos punitiva com as importações em termos de competitividade (as contribuições incidem apenas na comercialização dos produtos importados). JEL classification: H27; H77, H87.

Avaliação de projetos na presença de volatilidade: estudo de caso de empresas no setor de telecomunicações

Quando as empresas decidem se devem ou não investir em determinado projeto de investimentos a longo prazo (horizonte de 5 a 10 anos), algumas metodologias alternativas ao Fluxo de Caixa Descontado (FCD) podem se tornar úteis tanto para confirmar a viabilidade do negócio como para indicar o melhor momento para iniciar o Empreendimento. As análises que levam em conta a incerteza dos fluxos de caixa futuros e flexibilidade na data de início do projeto podem ser construídos com a abordagem estocástica, usando metodologias como a solução de equações diferenciais que descrevem o movimento browniano. Sob determinadas condições, as oportunidades de investimentos em projetos podem ser tratados como se fossem opções reais de compra, sem data de vencimento, como no modelo proposto por McDonald-Siegel (1986), para a tomada de decisões e momento ótimo para o investimento. Este trabalho analisa a viabilidade de investimentos no mercado de telecomunicações usando modelos não determinísticos, onde a variável mais relevante é a dispersão dos retornos, ou seja, que a variância representa o risco associado a determinado empreendimento.

On the purchasing power parity for Latin-American countries

The purpose of this paper is to test the hypothesis of long-run purchasing power parity (PPP) for all Latin American countries. These countries share similar economic history and contagious effects from currency crises, which might lead to comovements in their real exchange rates. New time series unit root tests found evidence of PPP for the vast majority of countries. In the panel data framework, tests for the null of unit root, null of stationarity, and unit root under multiple structural breaks indicated stationary real exchange rates. Thus, there is convincing evidence that PPP holds for Latin-American countries in the post-1980 period.

Nonparametric entropy-based tests of independence between stochastic processes

This paper develops nonparametric tests of independence between two stationary stochastic processes. The testing strategy boils down to gauging the closeness between the joint and the product of the marginal stationary densities. For that purpose, I take advantage of a generalized entropic measure so as to build a class of nonparametric tests of independence. Asymptotic normality and local power are derived using the functional delta method for kernels, whereas finite sample properties are investigated through Monte Carlo simulations.