305 research outputs found
Objective measurement of habitual sedentary behavior in pre-school children: comparison of activPAL with actigraph monitors
The Actigraph is well established for measurement of both physical activity and
sedentary behavior in children. The activPAL is being used increasingly in children, though with no published evidence on its use in free-living children to date. The present study compared the two monitors in preschool children. Children (n 23) wore both monitors simultaneously during waking hours for 5.6d and 10h/d. Daily mean percentage of time sedentary (nontranslocation of the trunk) was 74.6 (SD 6.8) for the Actigraph and 78.9 (SD 4.3) for activPAL. Daily mean percentage of time physically active (light intensity physical activity plus MVPA) was 25.4 (SD 6.8) for the Actigraph and 21.1 (SD 4.3) for the activPAL. Bland-Altman tests and paired t tests suggested small but statistically significant differences between the two monitors. Actigraph and activPAL estimates of sedentary behaviour and physical activity in young children are similar at a group level
Influence of molding and core sands matrix on the effectiveness of the microwaves absorption
The paper presents the results of applying microwaves to support the drying, redrying and hardening process of molding and core sands made of different types of matrix. In the tests of the microwave heating process a slot line measuring stand was used. Being based on the dielectric parameter measurement it enabled the evaluation of power losses of microwaves penetrating: chromite, magnesite, corundum, zircon and silica molding matrix samples. The survey revealed an impact of humidity and chemical compound of sands on microwave absorption. The study enabled the systematization of knowledge about the influence of selected types of matrix on the effectiveness of the microwave heating process
Exploration of Parameter Spaces in a Virtual Observatory
Like every other field of intellectual endeavor, astronomy is being
revolutionised by the advances in information technology. There is an ongoing
exponential growth in the volume, quality, and complexity of astronomical data
sets, mainly through large digital sky surveys and archives. The Virtual
Observatory (VO) concept represents a scientific and technological framework
needed to cope with this data flood. Systematic exploration of the observable
parameter spaces, covered by large digital sky surveys spanning a range of
wavelengths, will be one of the primary modes of research with a VO. This is
where the truly new discoveries will be made, and new insights be gained about
the already known astronomical objects and phenomena. We review some of the
methodological challenges posed by the analysis of large and complex data sets
expected in the VO-based research. The challenges are driven both by the size
and the complexity of the data sets (billions of data vectors in parameter
spaces of tens or hundreds of dimensions), by the heterogeneity of the data and
measurement errors, including differences in basic survey parameters for the
federated data sets (e.g., in the positional accuracy and resolution,
wavelength coverage, time baseline, etc.), various selection effects, as well
as the intrinsic clustering properties (functional form, topology) of the data
distributions in the parameter spaces of observed attributes. Answering these
challenges will require substantial collaborative efforts and partnerships
between astronomers, computer scientists, and statisticians.Comment: Invited review, 10 pages, Latex file with 4 eps figures, style files
included. To appear in Proc. SPIE, v. 4477 (2001
A technique to record the sedentary to walk movement during free living mobility : a comparison of healthy and stroke populations
Background
Hesitation between moving from a sedentary posture (lying/sitting) to walking is a characteristic of
mobility impaired individuals, as identified from laboratory studies. Knowing the extent to which this
hesitation occurs during everyday life would benefit rehabilitation research. This study aimed to
quantify this transition hesitation through a novel approach to analysing data from a physical activity
monitor based on a tri-axial accelerometer and compare results from two populations; stroke
patients and age-matched unimpaired controls.
Methods
Stroke patients living at home with early supported discharge (n=34, 68.9YO ± 11.8) and age matched
controls (n=30, 66.8YO ± 10.5) wore a physical activity monitor for 48hrs. The outputs from
the monitor were then used to determine the transitions from sedentary to walking. The time delay
between a sedentary posture ending and the start of walking classified four transition types: 1)
fluent (<=2s), 2) hesitant (>2s<=10s), 3) separated (>10s) and 4) a change from sedentary with no
registered walking to a return to sedentary.
Results
Control participants initiated walking after a sedentary posture on 92% of occasions. Most
commonly (43%) this was a fluent transition. In contrast stroke patients walked after changing from
a sedentary posture on 68% of occasions with only 9% of transitions classed as fluent, (p<0.05).
Discussion/Conclusion
A new data analysis technique reports the frequency of walking following a change in sedentary
position in stroke patients and healthy controls and characterises this transition according to the
time delay before walking. This technique creates opportunities to explore everyday mobility in
greater depth
Injecting Artificial Memory Errors Into a Running Computer Program
Single-event upsets (SEUs) or bitflips are computer memory errors caused by radiation. BITFLIPS (Basic Instrumentation Tool for Fault Localized Injection of Probabilistic SEUs) is a computer program that deliberately injects SEUs into another computer program, while the latter is running, for the purpose of evaluating the fault tolerance of that program. BITFLIPS was written as a plug-in extension of the open-source Valgrind debugging and profiling software. BITFLIPS can inject SEUs into any program that can be run on the Linux operating system, without needing to modify the program s source code. Further, if access to the original program source code is available, BITFLIPS offers fine-grained control over exactly when and which areas of memory (as specified via program variables) will be subjected to SEUs. The rate of injection of SEUs is controlled by specifying either a fault probability or a fault rate based on memory size and radiation exposure time, in units of SEUs per byte per second. BITFLIPS can also log each SEU that it injects and, if program source code is available, report the magnitude of effect of the SEU on a floating-point value or other program variable
Exploration of Large Digital Sky Surveys
We review some of the scientific opportunities and technical challenges posed
by the exploration of the large digital sky surveys, in the context of a
Virtual Observatory (VO). The VO paradigm will profoundly change the way
observational astronomy is done. Clustering analysis techniques can be used to
discover samples of rare, unusual, or even previously unknown types of
astronomical objects and phenomena. Exploration of the previously poorly probed
portions of the observable parameter space are especially promising. We
illustrate some of the possible types of studies with examples drawn from
DPOSS; much more complex and interesting applications are forthcoming.
Development of the new tools needed for an efficient exploration of these vast
data sets requires a synergy between astronomy and information sciences, with
great potential returns for both fields.Comment: To appear in: Mining the Sky, eds. A. Banday et al., ESO Astrophysics
Symposia, Berlin: Springer Verlag, in press (2001). Latex file, 18 pages, 6
encapsulated postscript figures, style files include
Technology for monitoring everyday prosthesis use: a systematic review
BACKGROUND
Understanding how prostheses are used in everyday life is central to the design, provision and evaluation of
prosthetic devices and associated services. This paper reviews the scientific literature on methodologies and
technologies that have been used to assess the daily use of both upper- and lower-limb prostheses. It discusses
the types of studies that have been undertaken, the technologies used to monitor physical activity, the benefits
of monitoring daily living and the barriers to long-term monitoring.
METHODS
A systematic literature search was conducted in PubMed, Web of Science, Scopus, CINAHL and EMBASE of
studies that monitored the activity of prosthesis-users during daily-living.
RESULTS
60 lower-limb studies and 9 upper-limb studies were identified for inclusion in the review. The first studies in
the lower-limb field date from the 1990s and the number has increased steadily since the early 2000s. In contrast,
the studies in the upper-limb field have only begun to emerge over the past few years. The early lower-limb
studies focused on the development or validation of actimeters, algorithms and/or scores for activity
classification. However, most of the recent lower-limb studies used activity monitoring to compare prosthetic components. The lower-limb studies mainly used step-counts as their only measure of activity, focusing on the
amount of activity, not the type and quality of movements. In comparison, the small number of upper-limb
studies were fairly evenly spread between development of algorithms, comparison of everyday activity to
clinical scores, and comparison of different prosthesis user populations. Most upper-limb papers reported the
degree of symmetry in activity levels between the arm with the prosthesis and the intact arm.
CONCLUSIONS
Activity monitoring technology used in conjunction with clinical scores and user feedback, offers significant
insights into how prostheses are used and whether they meet the userâs requirements. However, the cost, limited
battery-life and lack of availability in many countries mean that using sensors to understand the daily use of
prostheses and the types of activity being performed has not yet become a feasible standard clinical practice.
This review provides recommendations for the research and clinical communities to advance this area for the
benefit of prosthesis users
pyMCMA: Uniformly distributed Pareto-front representation
pyMCMA is the Python implementation of a novel method for autonomous computation of the Pareto-front representation composed of efficient solutions distributed uniformly in terms of distances between neighbor Pareto solutions. pyMCMA supports scientific, i.e. objective, model analysis by providing preference-free Pareto front representation. pyMCMA seamlessly integrates independently developed substantive models. The computed Pareto-front, also for more than two criteria, is visualized by interactive parallel coordinate plot, as well as by charts of criteria pairs. Moreover, pyMCMA optionally exports the results for problems-specific analysis in the substantive modelâs variables space. The pyMCMA functionality is illustrated by an analysis of Chinaâs liquid fuel production model
West End Walkers 65+: a randomised controlled trial of a primary care-based walking intervention for older adults:study rationale and design
<p>Background: In Scotland, older adults are a key target group for physical activity intervention due to the large proportion who are inactive. The health benefits of an active lifestyle are well established but more research is required on the most effective interventions to increase activity in older adults. The 'West End Walkers 65+' randomised controlled trial aims to examine the feasibility of delivering a pedometer-based walking intervention to adults aged â„65 years through a primary care setting and to determine the efficacy of this pilot. The study rationale, protocol and recruitment process are discussed in this paper.</p>
<p>Methods/Design: The intervention consisted of a 12-week pedometer-based graduated walking programme and physical activity consultations. Participants were randomised into an immediate intervention group (immediate group) or a 12-week waiting list control group (delayed group) who then received the intervention. For the pilot element of this study, the primary outcome measure was pedometer step counts. Secondary outcome measures of sedentary time and physical activity (time spent lying/sitting, standing or walking; activPALâą monitor), mood (Positive and Negative Affect Schedule), functional ability (Perceived Motor-Efficacy Scale for Older Adults), quality of life (Short-Form (36) Health Survey version 2) and loneliness (UCLA Loneliness Scale) were assessed. Focus groups with participants and semi-structured interviews with the research team captured their experiences of the intervention. The feasibility component of this trial examined recruitment via primary care and retention of participants, appropriateness of the intervention for older adults and the delivery of the intervention by a practice nurse.</p>
<p>Discussion: West End Walkers 65+ will determine the feasibility and pilot the efficacy of delivering a pedometer-based walking intervention through primary care to Scottish adults aged â„65 years. The study will also examine the effect of the intervention on the well-being of participants and gain an insight into both participant and research team member experiences of the intervention.</p>
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