Children in organized hockey: How much physical activity do they really get?

International Journal of Exercise Science 8(2): 184-191, 2015. For optimal physical and mental health and child growth, development and maturation, the Canadian physical activity guidelines recommend children participate in minimally 60 minutes of moderate intense physical activity each day. It is often believed that children’s participation in sport provides sufficient physical activity to meet these recommendations. The purpose of this study was to measure the amount and intensity of physical activity obtained by children participating in a regularly scheduled ice hockey practice and game. Actigraph GT3X triaxial accelerometers (motion detectors) were used to determine the intensity and amount of physical activity obtained by 9- and 10-year old children (16 boys; 1 girl) during an ice hockey practice and game. Downloaded accelerometer counts were converted to minutes of moderate, hard, or very-hard physical activity. On average, participants spent 30.2 ± 10.8 min or 43.1% of their 70-min ice hockey practice and 22.3 ± 6.3 min or 28.2% of their 80-min ice hockey game in moderate or more intense physical activity. Children’s participation in one session of organized ice hockey, whether a practice or a game, did not meet the minimal daily physical activity recommendation for children. Thus parents, teachers, coaches, and physical activity practitioners must create, support, and encourage additional opportunities for children to engage in physical activity of sufficient intensity for optimal growth and development and to ensure physical and mental health and well-being

Large scale anthropogenic reduction of forest cover in Last Glacial Maximum Europe

Reconstructions of the vegetation of Europe during the Last Glacial Maximum (LGM) are an enigma. Pollen-based analyses have suggested that Europe was largely covered by steppe and tundra, and forests persisted only in small refugia. Climate-vegetation model simulations on the other hand have consistently suggested that broad areas of Europe would have been suitable for forest, even in the depths of the last glaciation. Here we reconcile models with data by demonstrating that the highly mobile groups of hunter-gatherers that inhabited Europe at the LGM could have substantially reduced forest cover through the ignition of wildfires. Similar to hunter-gatherers of the more recent past, Upper Paleolithic humans were masters of the use of fire, and preferred inhabiting semi-open landscapes to facilitate foraging, hunting and travel. Incorporating human agency into a dynamic vegetation-fire model and simulating forest cover shows that even small increases in wildfire frequency over natural background levels resulted in large changes in the forested area of Europe, in part because trees were already stressed by low atmospheric CO2 concentrations and the cold, dry, and highly variable climate. Our results suggest that the impact of humans on the glacial landscape of Europe may be one of the earliest large-scale anthropogenic modifications of the earth system

Contributions of After School Programs to the Development of Fundamental Movement Skills in Children

International Journal of Exercise Science 7(3) : 236-249, 2014. Fundamental movement skill (FMS) proficiency or the ability to perform basic skills (e.g., throwing, catching and jumping) has been linked to participation in lifelong physical activity. FMS proficiency amongst children has declined in the previous 15 years, with more children performing FMS at a low-mastery level. These declines may help explain the insufficient levels of participation in health promoting physical activity seen in today’s youth. The after school time period (e.g., 3 to 6 p.m.), is increasingly considered an opportune time for physical activity interventions. To date, little research has examined the potential for after school programming to improve FMS proficiency. Participants (n=40, 6-10 years) of two existent physical activity based after school programs, a low-organized games and a sports-based program, were pre- and post-tested for FMS proficiency using the Test of Gross Motor Development-2 (TGMD-2) over an 11-week period. The sports-based program participants showed no improvement in FMS over the 11-week study (p=0.91, eta2=0.00) and the games-based program participants significantly improved their proficiency (p=0.00, eta2=0.30). No significant (p=0.13, eta2 = 0.06), differences were found in change in FMS scores between the low-organized games program participants and the sport-based program participants. These results suggest that after school programs with a low-organized games-based focus may support a moderate improvement in FMS proficiency in young children. Better training of after school program leaders on how to teach FMS may be necessary to assist children in acquiring sufficient proficiency in FMS

Interval Selection in the Streaming Model

A set of intervals is independent when the intervals are pairwise disjoint. In the interval selection problem we are given a set $\mathbb{I}$ of intervals and we want to find an independent subset of intervals of largest cardinality. Let $\alpha(\mathbb{I})$ denote the cardinality of an optimal solution. We discuss the estimation of $\alpha(\mathbb{I})$ in the streaming model, where we only have one-time, sequential access to the input intervals, the endpoints of the intervals lie in $\{1,...,n \}$, and the amount of the memory is constrained. For intervals of different sizes, we provide an algorithm in the data stream model that computes an estimate $\hat\alpha$ of $\alpha(\mathbb{I})$ that, with probability at least $2/3$, satisfies $\tfrac 12(1-\varepsilon) \alpha(\mathbb{I}) \le \hat\alpha \le \alpha(\mathbb{I})$. For same-length intervals, we provide another algorithm in the data stream model that computes an estimate $\hat\alpha$ of $\alpha(\mathbb{I})$ that, with probability at least $2/3$, satisfies $\tfrac 23(1-\varepsilon) \alpha(\mathbb{I}) \le \hat\alpha \le \alpha(\mathbb{I})$. The space used by our algorithms is bounded by a polynomial in $\varepsilon^{-1}$ and $\log n$. We also show that no better estimations can be achieved using $o(n)$ bits of storage. We also develop new, approximate solutions to the interval selection problem, where we want to report a feasible solution, that use $O(\alpha(\mathbb{I}))$ space. Our algorithms for the interval selection problem match the optimal results by Emek, Halld{\'o}rsson and Ros{\'e}n [Space-Constrained Interval Selection, ICALP 2012], but are much simpler.Comment: Minor correction

Sensitivity Analysis of List Scheduling Heuristics

When jobs have to be processed on a set of identical parallel machines so as to minimize the makespan of the schedule, list scheduling rules form a popular class of heuristics. The order in which jobs appear on the list is assumed here to be determined by the relative size of their processing times; well known special cases are the LPT rule and the SPT rule, in which the jobs are ordered according to non-increasing and non-decreasing processing time respectively. When one of the job processing times is gradually increased, the schedule produced by a list scheduling rule will be affected in a manner reflecting its sensitivity to data perturbations. We analyze this phenomenon and obtain analytical support for the intuitively plausible notion that the sensitivity of a list scheduling rule increases with the quality of the schedule produced

Fast Color Quantization Using Weighted Sort-Means Clustering

Color quantization is an important operation with numerous applications in graphics and image processing. Most quantization methods are essentially based on data clustering algorithms. However, despite its popularity as a general purpose clustering algorithm, k-means has not received much respect in the color quantization literature because of its high computational requirements and sensitivity to initialization. In this paper, a fast color quantization method based on k-means is presented. The method involves several modifications to the conventional (batch) k-means algorithm including data reduction, sample weighting, and the use of triangle inequality to speed up the nearest neighbor search. Experiments on a diverse set of images demonstrate that, with the proposed modifications, k-means becomes very competitive with state-of-the-art color quantization methods in terms of both effectiveness and efficiency.Comment: 30 pages, 2 figures, 4 table

Ultrasound transducer positioning aid for fetal heart rate monitoring

Fetal heart rate (fHR) monitoring is usually performed by Doppler ultrasound (US) techniques. For reliable fHR measurements it is required that the fetal heart is located within the US beam. In clinical practice, clinicians palpate the maternal abdomen to identify the fetal presentation and then the US transducer is fixated on the maternal abdomen where the best fHR signal can be obtained. Finding the optimal transducer position is done by listening to the strength of the Doppler audio output and relying on a signal quality indicator of the cardiotocographic (CTG) measurement system. Due to displacement of the US transducer or displacement of the fetal heart out of the US beam, the fHR signal may be lost. Therefore, it is often necessary that the obstetrician repeats the tedious procedure of US transducer positioning to avoid long periods of fHR signal loss. An intuitive US transducer positioning aid would be highly desirable to increase the work flow for the clinical staff. In this paper, the possibility to determine the fetal heart location with respect to the transducer by exploiting the received signal power in the transducer elements is shown. A commercially available US transducer used for fHR monitoring is connected to an US open platform, which allows individual driving of the elements and raw US data acquisition. Based on the power of the received Doppler signals in the transducer elements, the fetal heart location can be estimated. A beating fetal heart setup was designed and realized for validation. The experimental results show the feasibility of estimating the fetal heart location with the proposed method. This can be used to support clinicians in finding the optimal transducer position for fHR monitoring more easily

Perceptions, experiences, barriers and facilitators regarding nutritional intake of patients with chronic limb threatening ischemia:a qualitative study

Objective: Patients with chronic limb threatening ischemia (CLTI) are at high risk for amputation and other cardiovascular adverse events. Nutrition-related symptoms and malnutrition are common in the CLTI population, and lead to worse clinical outcomes. Understanding of the factors influencing nutritional intake is required to determine whether optimization of nutritional intake in this population requires interventions. Therefore, this study aimed to describe perceptions and experiences on nutrition of patients with CLTI, and to identify perceived barriers and facilitators influencing their nutritional intake.Methods: In this phenomenological qualitative study, individual semi-structured, face-to-face interviews were conducted with patients with CLTI who lived independently. Interviews were transcribed verbatim, and reflexive thematic analysis was performed.Results: Twelve participants were interviewed. Five themes were generated: (1) lack of nutritional risk perception, (2) role of nutrition for health, functioning and surviving, (3) multiple factors influencing nutritional intake, (4) limited nutritional advice, and (5) no intention to change current nutritional intake.Conclusion: Patients with CLTI perceive nutritional intake as a necessity to survive and function. Patients express limited risk perception regarding adequate nutritional intake and undernutrition. Nutritional intake is mainly based on non-health related factors, as habits and taste, and multiple barriers hinder nutritional intake. Patients received no or only limited nutritional advice. Together this leads to an expressed lack of intention to change nutritional intake. Findings of this study stress the urgency for patient-centered nutritional support, to increase nutrition-related knowledge and motivation, to prevent or treat undernutrition, and may improve clinical outcomes in patients with CLTI