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Michela Leonardi, Guido Barbujani, Andrea Manica
Archaeological evidence shows that, in the long run, Neolitization (the transition from foraging to food production) was associated with demographic growth. We used two methods (patterns of linkage disequilibrium from whole-genome SNPs and MSMC estimates on genomes) to reconstruct the demographic profiles for respectively 64 and 24 modern-day populations with contrasting lifestyles across the Old World (sub-Saharan Africa, south-eastern Asia, Siberia). Surprisingly, in all regions, food producers had larger effective population sizes (N e ) than foragers already 20 k years ago, well before the Neolithic revolution...
June 14, 2017: Scientific Reports
Giovanni Gasbarrini, Fiorenza Bonvicini, Annagiulia Gramenzi
Gut microbiota promotes healthy effects on the host and prevents diseases. Probiotic (probios, for life) are defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host." At the beginning of 1900s Louis Pasteur identified the microorganisms responsible for the process of fermentation, whereas E. Metchnikoff associated the enhanced longevity of Bulgarian rural people to the regular consumption of fermented dairy products such as yogurt. He suggested that lactobacilli might counteract the putrefactive effects of gastrointestinal metabolism that contributed to illness and aging...
November 2016: Journal of Clinical Gastroenterology
Kai Way Li, Fanxing Meng, Wei Zhang
Solid particles on the floor, both dry and wet, are common but their effects on the friction on the floor were seldom discussed in the literature. In this study, friction measurements were conducted to test the effects of particle size of solid contaminants on the friction coefficient on the floor under footwear, floor, and surface conditions. The results supported the hypothesis that particle size of solids affected the friction coefficient and the effects depended on footwear, floor, and surface conditions...
2014: International Journal of Occupational Safety and Ergonomics: JOSE
Wen-Ruey Chang, Simon Matz, Raoul Grönqvist, Mikko Hirvonen
For slips and falls, friction is widely used as an indicator of surface slipperiness. Surface parameters, including surface roughness and waviness, were shown to influence friction by correlating individual surface parameters with the measured friction. A collective input from multiple surface parameters as a predictor of friction, however, could provide a broader perspective on the contributions from all the surface parameters evaluated. The objective of this study was to develop regression models between the surface parameters and measured friction...
January 2010: Applied Ergonomics
No abstract text is available yet for this article.
August 1948: Fogorvosi Szemle
Kai Way Li, Horng Huei Wu, Yu-Chang Lin
Slipping and falling are common phenomena in both workplaces and our daily activities. The risks associated with slipping and falling are related to the materials of footwear/floor, contamination condition, and geometric design of the sole. Shoe soles of various tread design are very common. Tread pattern of the shoe affects friction especially under liquid-contaminated conditions. Verification of the effects of tread groove depth is significant in assisting designers in designing proper footwear for workers exposed to slippery floor conditions...
November 2006: Applied Ergonomics
Tim Joganich, Len Mc Cuen
In recent years, walkway slip-resistance testing with grooved NTL (Neolite Test Liners) has been the subject of research, as well as used in field investigation practices. Recent research shows that differences between non-grooved and grooved test feet do exist, especially under wet conditions. It is not known how the number of grooves influences the slip resistance. This study investigates the influence of groove count on slip resistance under both wet and dry conditions using the PIAST tribometer. Test feet with 1, 3, 5, 7, 9, 11, 13, and 15 grooves and a non-grooved test foot were used...
September 2005: Journal of Forensic Sciences
Wen-Ruey Chang, Raoul Grönqvist, Mikko Hirvonen, Simon Matz
Friction is widely used as an indicator of surface slipperiness in preventing accidents in slips and falls. Surface texture affects friction, but it is not clear which surface characteristics are better correlated with friction. Highly correlated surface characteristics could be used as potential interventions to prevent slip and fall accidents. The dynamic friction between quarry tiles and a commonly used sole testing material, Neolite, using three different mixtures of glycerol and water as contaminants at the interface was correlated with the surface parameters of the tile surfaces...
June 22, 2004: Ergonomics
W R Chang
Surface roughness affects friction, but it is not clear what surface roughness characteristics are better correlated with friction. The average of the maximum height above the mean line in each cut-off length (Rpm) and the arithmetical average of surface slope (deltaa) had the highest correlation with dynamic friction coefficient in a previous study. The previous study was expanded to two different footwear materials and four different contaminants on a porcelain tile in the current investigation. The results showed that dynamic friction decreased as the interface speed and glycerol content in the contaminant were increased due to the hydrodynamic lubrication effect...
April 2001: Applied Ergonomics
D B Chaffin, J C Woldstad, A Trujillo
A variety of slip measurement devices exist that provide estimates of both static and dynamic coefficient-of-friction (COF) values between one's shoes and the floor. Unfortunately, different shoe sole/heel materials, floor conditions, and contaminants will affect the tests in ways that result in widely varying COF estimates. This paper reviews the basic physics of such tests and describes a set of experiments to determine the static and dynamic COF values under operating conditions known to exist in different jobs...
May 1992: American Industrial Hygiene Association Journal
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