scholarly journals The Development and Precision of a Custom-Made Skitester

2021 ◽  
Vol 7 ◽  
Author(s):  
Teemu Lemmettylä ◽  
Teemu Heikkinen ◽  
Olli Ohtonen ◽  
Stefan Lindinger ◽  
Vesa Linnamo
Keyword(s):  
Weather Conditions ◽  
Physical Characteristics ◽  
Measurement Unit ◽  
Preparation Process ◽  
Direct Influence ◽  
Relative Variation ◽  
Custom Made ◽  
Cross Country Skiing ◽  
Cross Country

In the sport of cross-country skiing, equipment has a direct influence on results. Ski teams do extensive testing of different ski base grinds and products on a yearly basis. To achieve reliable results, the quality of methods used for testing skis needs to be taken in to account in addition to factors including the physical characteristics of testing personnel and changes in weather conditions. The aim of this study was to introduce a custom-made skitester, that was developed for testing skis on real snow, in laboratory conditions, and to evaluate its precision. The current skitester is capable of glide testing both classic and skate skis as well as kick simulation for the testing of grip waxes. In the present study, glide testing precision was completed in three different conditions. Velocity and pressure of skis were evaluated in three different temperature conditions. During kick simulation, precision was determined in one temperature condition. For glide testing, the precision of the measurement unit was able to distinguish the differences between skis with a relative variation of 0.6–1.1%. However, the track preparation process caused variation. For kick simulation, precision of the measurement unit was slightly higher (2.5%), and track preparation caused less variation. The skitester is capable of distinguishing the differences between both skate and classic cross-country skis with certain limitations.

The Velocity and Energy Profiles of Elite Cross-Country Skiers Executing Downhill Turns With Different Radii

2014 ◽  
Vol 9 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Øyvind Sandbakk ◽  
Silvana Bucher Sandbakk ◽  
Matej Supej ◽  
Hans-Christer Holmberg
Keyword(s):  
Lower Energy ◽  
Satellite System ◽  
Energy Characteristics ◽  
Energy Profiles ◽  
Single Turn ◽  
Turn Radius ◽  
Cross Country Skiing ◽  
Cross Country ◽  
Global Navigation Satellite

This study examined the influence of turn radius on velocity and energy profiles when skidding and step turning during more and less effective downhill turns while cross-country skiing. Thirteen elite female cross-country skiers performed single turns with a 9- or 12-m radius using the skidding technique and a 12- or 15-m radius with step turning. Mechanical parameters were monitored using a real-time kinematic Global Navigation Satellite System and video analysis. Step turning was more effective during all phases of a turn, leading to higher velocities than skidding (P < .05). With both techniques, a greater radius was associated with higher velocity (P < .05), but the quality of turning, as assessed on the basis of energy characteristics, was the same. More effective skidding turns involved more pronounced deceleration early in the turn and maintenance of higher velocity thereafter, while more effective step turning involved lower energy dissipation during the latter half of the turn. In conclusion, the single-turn analysis employed here reveals differences in the various techniques chosen by elite cross-country skiers when executing downhill turns of varying radii and can be used to assess the quality of such turns.

scholarly journals Methodological Guidelines Designed to Improve the Quality of Research on Cross-Country Skiing

2021 ◽  
Author(s):  
Barbara Pellegrini ◽  
Øyvind Sandbakk ◽  
Thomas Stöggl ◽  
Matej Supej ◽  
Niels Ørtenblad ◽  
...  
Keyword(s):  
Measuring Equipment ◽  
Reliability And Validity ◽  
Cross Country Skiing ◽  
Cross Country ◽  
International Experts ◽  
Methodological Guidelines ◽  
Quality Of Research ◽  
Biomechanical Measurements ◽  
Variable Topography

AbstractCross-country (XC) ski races involve a variety of formats, two different techniques and tracks with highly variable topography and environmental conditions. In addition, XC skiing is a major component of both Nordic combined and biathlon competitions. Research in this area, both in the laboratory and field, encounters certain difficulties that may reduce the reliability and validity of the data obtained, as well as complicate comparisons between studies. Here, 13 international experts propose specific guidelines designed to enhance the quality of research and publications on XC skiing, as well as on the biathlon and Nordic combined skiing. We consider biomechanical (kinematic, kinetic and neuromuscular) and physiological methodology (at the systemic and/or muscle level), providing recommendations for standardization/control of the experimental setup. We describe the types of measuring equipment and technology that are most suitable in this context. Moreover, we also deal with certain aspects of nomenclature of the classical and skating sub-techniques. In addition to enhancing the quality of studies on XC skiing, Nordic combined and biathlon, our guidelines should also be of value for sport scientists and coaches in other disciplines where physiological and/or biomechanical measurements are performed in the laboratory and/or outdoors.

scholarly journals Embedded inertial measurement unit reveals pole lean angle for cross-country skiing

2020 ◽  
Vol 23 (1) ◽  
Author(s):  
John Bruzzo ◽  
Noel C. Perkins ◽  
Aki Mikkola
Keyword(s):  
Measurement System ◽  
Inertial Measurement Unit ◽  
Angular Rate ◽  
Measurement Unit ◽  
Inertial Measurement ◽  
Lean Angle ◽  
Cross Country Skiing ◽  
Cross Country ◽  
Mean Differences ◽  
Mean Square Errors

AbstractThis study introduces an inertial measurement unit-based measurement system for resolving the dynamic lean angle of a ski pole during double poling while cross-country skiing. The measurement system estimates both the pole lean angle and pole–terrain contact events. Reported are results from 20 trials providing validated estimates of ski pole lean angle and the timing of pole plant and pole lift events. The pole lean angle is estimated from a complementary filter that fuses estimates of orientation from the embedded accelerometer and angular rate gyro. Validation follows from comparison with video capture measurements. Bland–Altman analysis showed agreement between the two measurement modalities with less than 5% bias in the mean differences (relative to the lean angle range of motion). Companion correlation analysis confirms strong correlation ($$r = 0.99$$ r = 0.99 ) between the inertial measurement unit and video-estimated lean angles and with mean root-mean-square errors below 4.5$$^{\circ }$$ ∘ .

Trust in the Police: Cross-country Comparisons

2012 ◽  
pp. 24-47
Author(s):  
V. Gimpelson ◽  
G. Monusova
Keyword(s):  
Public Opinion ◽  
Public Attitudes ◽  
Crime Rates ◽  
Authoritarian Regimes ◽  
Data Sets ◽  
The Public ◽  
Positive Attitudes ◽  
Cross Country ◽  
Police Activity

Using different cross-country data sets and simple econometric techniques we study public attitudes towards the police. More positive attitudes are more likely to emerge in the countries that have better functioning democratic institutions, less prone to corruption but enjoy more transparent and accountable police activity. This has a stronger impact on the public opinion (trust and attitudes) than objective crime rates or density of policemen. Citizens tend to trust more in those (policemen) with whom they share common values and can have some control over. The latter is a function of democracy. In authoritarian countries — “police states” — this tendency may not work directly. When we move from semi-authoritarian countries to openly authoritarian ones the trust in the police measured by surveys can also rise. As a result, the trust appears to be U-shaped along the quality of government axis. This phenomenon can be explained with two simple facts. First, publicly spread information concerning police activity in authoritarian countries is strongly controlled; second, the police itself is better controlled by authoritarian regimes which are afraid of dangerous (for them) erosion of this institution.

Engineers or Lawyers? Institutions and Demand for Higher Education

2012 ◽  
pp. 30-51 ◽  
Author(s):  
T. Natkhov ◽  
L. Polishchuk
Keyword(s):  
Higher Education ◽  
Public Administration ◽  
Rule Of Law ◽  
Transmission Channel ◽  
Demand For Education ◽  
Fields Of Study ◽  
Quality Of Institutions ◽  
Cross Country ◽  
Rules Of The Game

Law and public administration schools in Russia vastly exceed in their popularity sciences and engineering. We relate such lopsided demand for higher education to the quality of institutions setting “rules of the game” in economy and society. Cross-country and Russian interregional data indicate the quality of institutions (rule of law, protection of property rights etc.) is negatively associated with the demand for education in law, and positively — in sciences and engineering. More gifted younger people are particularly sensitive to the quality of institutions in choosing their fields of study, and such selection is an important transmission channel between institutions and economic growth.

Water quality of Tampa Bay, Florida : wet-weather conditions, October 1971

1975 ◽  
Author(s):  
Carl R. Goodwin ◽  
Joseph S. Rosenshein ◽  
D.M. Michaelis
Keyword(s):  
Water Quality ◽  
Weather Conditions ◽  
Tampa Bay ◽  
Wet Weather

scholarly journals Physical Characteristics and Microbial Quality of Ostrich Meat in Relation to the Type of Packaging and Refrigerator Storage Time

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3445
Author(s):  
Olaf K. Horbańczuk ◽  
Artur Jóźwik ◽  
Jarosław Wyrwisz ◽  
Joanna Marchewka ◽  
Agnieszka Wierzbicka
Keyword(s):  
Storage Time ◽  
Modified Atmosphere Packaging ◽  
Physical Characteristics ◽  
Modified Atmosphere ◽  
Packaging System ◽  
Initial Ph ◽  
Viable Bacteria ◽  
L Value ◽  
Meat Samples

The aim of this study was to evaluate the effect of the packaging system type on the physical characteristics and microbial changes in ostrich meat during refrigerated storage. The applied packaging systems were vacuum packaging (VP) and modified atmosphere packaging (MAP) using two combinations of gases: MAP1 (40% O2/40% CO2/20% N2) and MAP2 (60% O2/30% CO2/10% N2). Eight meat samples were obtained in three replicates for all parameters, except for pH, for which six replicates were obtained from the M. ilifibularis (IF) muscle, and were stored in a refrigerator at 2 °C and analyzed at 0, 4, 8, 12 and 16 days for the effect of packaging methods on physical meat quality. The initial pH (5.99) decreased at the end of the storage time for MAP1 to 5.81, whereas VP was stable from day 0 to 12 and increased up to 6.08 on day 16. Regarding meat color, the L* value increased during storage for MAP1 and MAP2 from 36.99 to 40.75 and 41.60, respectively, whereas it declined for VP to 34.22. The same tendencies were reported for redness (a*) and yellowness (b*). Drip loss was the lowest in MAP1 and highest in VP. The lowest total viable bacteria counts were identified in VP, as compared to MAP1 and MAP2.

Robust Environmental Sensing Using UAVs

2021 ◽  
Vol 2 (4) ◽  
pp. 1-20
Author(s):  
Ahmed Boubrima ◽  
Edward W. Knightly
Keyword(s):  
Air Pollution ◽  
Gas Sensors ◽  
High Performance ◽  
Weather Conditions ◽  
Ambient Air ◽  
Mission Planning ◽  
Pollution Monitoring ◽  
Compound Pollution ◽  
Planning Algorithm

In this article, we first investigate the quality of aerial air pollution measurements and characterize the main error sources of drone-mounted gas sensors. To that end, we build ASTRO+, an aerial-ground pollution monitoring platform, and use it to collect a comprehensive dataset of both aerial and reference air pollution measurements. We show that the dynamic airflow caused by drones affects temperature and humidity levels of the ambient air, which then affect the measurement quality of gas sensors. Then, in the second part of this article, we leverage the effects of weather conditions on pollution measurements’ quality in order to design an unmanned aerial vehicle mission planning algorithm that adapts the trajectory of the drones while taking into account the quality of aerial measurements. We evaluate our mission planning approach based on a Volatile Organic Compound pollution dataset and show a high-performance improvement that is maintained even when pollution dynamics are high.

scholarly journals Effectiveness of custom-made foot orthoses in patients with systemic lupus erythaematosus: protocol for a randomised controlled trial

BMJ Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. e042627
Author(s):  
María Reina-Bueno ◽  
María del Carmen Vázquez-Bautista ◽  
Inmaculada C Palomo-Toucedo ◽  
Gabriel Domínguez-Maldonado ◽  
José Manuel Castillo-López ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Randomised Controlled Trial ◽  
Outcome Measures ◽  
Controlled Trial ◽  
Secondary Outcome ◽  
Foot Orthoses ◽  
Systemic Lupus ◽  
Custom Made ◽  
Randomised Controlled

IntroductionSystemic lupus erythaematosus (SLE) is a chronic autoimmune disease of heterogeneous involvement. The disease may affect feet with a high prevalence of symptoms such as, for example, pain, forefoot and rearfoot deformities, and biomechanics dysfunctions. Custom-made foot orthoses (CMFO) have been previously reported to be effective in patients with other rheumatic diseases. However, as far as the authors know, there exist no studies about their effectiveness in SLE. This study aims at determining the effect of CMFO versus placebo flat cushioning insoles on pain, foot functionality, fatigue and quality of life in patients with SLE.Methods and analysisA randomised controlled trial would compare the effects of (1) CMFO and group B, which received a placebo, flat cushioning insoles, for 3 months. The main outcome measures are foot pain, foot functionality and foot-related disability. The secondary outcome measures are fatigue and quality of life.Ethics and disseminationThe study has been approved by the Portal de Ética de la Investigación Biomédica de Andalucía ethical committee 1494-N-19. The results will be disseminated regardless of the magnitude or direction of effect.Trial registartion numberClinicaltrials.gov identifier NCT04098055.

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