67 resultados para Minimum quantity lubrication


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Background: Schools are an ideal setting in which to involve children in research. Yet for investigators wishing to work in these settings, there are few method papers providing insights into working efficiently in this setting.

Objective: The aim of this paper is to describe the five strategies used to increase response rates, data quality and quantity in the TRansport Environment and Kids (TREK) project.

Setting: The TREK project examined the association between neighbourhood urban design and active transport in Grade 5–7 school children (n = 1480) attending 25 primary schools in metropolitan Perth, Western Australia during 2007.

Method: Children completed several survey components during school time (i.e. questionnaire, mapping activity, travel diary and anthropometric measurements) and at home (i.e. pedometer study, parent questionnaire).

Results: Overall, 69.4% of schools and 56.6% of children agreed to participate in the study and, of these, 89.9% returned a completed travel diary, 97.8% returned their pedometer and 88.8% of parents returned their questionnaire. These return rates are superior to similar studies. Five strategies appeared important: (1) building positive relationships with key school personnel; (2) child-centred approaches to survey development; (3) comprehensive classroom management techniques to standardize and optimize group sessions; (4) extensive follow-up procedures for collecting survey items; and (5) a specially designed data management/monitoring system.

Conclusion: Sharing methodological approaches for obtaining high-quality data will ensure research opportunities within schools are maximized. These methodological issues have implications for planning, budgeting and implementing future research.

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The field metabolic rate (FMR) of a free-ranging animal can be considered as the sum of its maintenance costs (minimum metabolic rate, MMR) and additional costs associated with thermoregulation, digestion, production and activity. However, the relationships between FMR and BMR and how they relate to behaviour and extrinsic influences is not clear. In seabirds, FMR has been shown to increase during the breeding season. This is presumed to be the result of an increase in foraging activity, stimulated by increased food demands from growing chicks, but few studies have investigated in detail the factors that underlie these increases. We studied free-ranging Australasian gannets (Morus serrator) throughout their 5 month breeding season, and evaluated FMR, MMR and activity-related metabolic costs on a daily basis using the heart rate method. In addition, we simultaneously recorded behaviour (flying and diving) in the same individuals. FMR increased steadily throughout the breeding season, increasing by 11% from the incubation period to the long chick-brooding period. However, this was not accompanied by either an increase in flying or diving behaviour, or an increase in the energetic costs of activity. Instead, the changes in FMR could be explained exclusively by a progressive increase in MMR. Seasonal changes in MMR could be due to a change in body composition or a decrease in body condition associated with changing the allocation of resources between provisioning adults and growing chicks. Our study highlights the importance of measuring physiological parameters continuously in free-ranging animals in order to understand fully the mechanisms underpinning seasonal changes in physiology and behaviour.

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Normal (e.g., adhesion) and lateral (friction) forces were measured between physisorbed and chemically grafted layers of hyaluronic acid (HA), an anionic polyelectrolyte in the presence of lubricin (Lub), a mucinous glycoprotein, on mica surfaces using a surface forces apparatus (SFA). This work demonstrates that high friction coefficients between the surfaces do not necessarily correlate with surface damage and that chemically grafted HA acts synergistically with Lub to provide friction reduction and enhanced wear protection to the surfaces. Surface immobilization of HA by grafting is necessary for such wear protection. Increasing the concentration of Lub enhances the threshold load that a chemically grafted HA surface can be subjected to before the onset of wear. Addition of Lub does not have any beneficial effect if HA is physisorbed to the mica surfaces. Damage occurs at loads less than 1 mN regardless of the amount of Lub, indicating that the molecules in the bulk play little or no role in protecting the surfaces from damage. Lub penetrates into the chemically bound HA to form a visco-elastic gel that reduces the coefficient of friction as well as boosts the strength of the surface against abrasive wear (damage).

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Background:
While alcohol consumption and heavy episodic (binge) drinking are well-established predictors of male-to-male alcohol-related aggression (MMARA), the role of the father-son relationship in MMARA has yet to be explored.
Methods:
This study therefore examined whether fathering by the biological father rather than another father figure, negative fathering, and gender role modeled by the father figure were significant predictors of involvement in MMARA, once drinking frequency and quantity and heavy episodic drinking were controlled for. A total of 121 university students aged 18 to 25 years (M = 20.63, SD = 1.77 years) voluntarily completed the online questionnaire.
Results:
The only significant predictors of perpetration of MMARA were a more abusive paternal relationship and drinking quantity (number of standard drinks usually consumed when drinking).
Conclusions:
Negative father-son relationships may play a role in fostering young men's perpetration of MMARA in the barroom context. © 2013 by the Research Society on Alcoholism.

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Articular cartilage is an example of a highly efficacious water-based, natural lubrication system that is optimized to provide low friction and wear protection at both low and high loads and sliding velocities. One of the secrets of cartilage's superior tribology comes from a unique, multimodal lubrication strategy consisting of both a fluid pressurization mediated lubrication mechanism and a boundary lubrication mechanism supported by surface bound macromolecules. Using a reconstituted network of highly interconnected cellulose fibers and simple modification through the immobilization of polyelectrolytes, we have recreated many of the mechanical and chemical properties of cartilage and the cartilage lubrication system to produce a purely synthetic material system that exhibits some of the same lubrication mechanisms, time dependent friction response, and high wear resistance as natural cartilage tissue. Friction and wear studies demonstrate how the properties of the cellulose fiber network can be used to control and optimize the lubrication and wear resistance of the material surfaces and highlight what key features of cartilage should be duplicated in order to produce a cartilage-mimetic lubrication system.

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Recently, nonnegative matrix factorization (NMF) attracts more and more attentions for the promising of wide applications. A problem that still remains is that, however, the factors resulted from it may not necessarily be realistically interpretable. Some constraints are usually added to the standard NMF to generate such interpretive results. In this paper, a minimum-volume constrained NMF is proposed and an efficient multiplicative update algorithm is developed based on the natural gradient optimization. The proposed method can be applied to the blind source separation (BSS) problem, a hot topic with many potential applications, especially if the sources are mutually dependent. Simulation results of BSS for images show the superiority of the proposed method.

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Despite Information Communication Technology (ICT) can help to improve efficiency and Enterprise Resource Planning (ERP) system has been widely perceives as an efficient mean, diffusion rate is slow in construction industry and amongst quantity surveying profession. Today, quantity surveyor must frequently communicate with other stakeholder throughout the design and construct process and using information technology is a must. The more technologies evolve, the more quantity surveying with change and evolve to utilize these technologies. This paper, through literature review, firstly identifies perceived benefits of using ICT/ERP system, secondly concludes the critical success factors that may affect decision of adopting ICT/ERP tool in practice, and thirdly to suggest three effective evaluation tools before/after implementing ICT/ERP strategy. The ultimate goal is to advise how Australian quantity surveyors (QS) can utilize ICT and ERP system to improve efficiency.

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Quantity surveying is the key profession in cost management for construction business. However, construction industry is notorious in using information technology that makes reporting inefficient. A construction company in Hong Kong has been using an enterprise resource planning system as the information communication technology in management and cost reporting backbone since 2003. This paper investigates if such system represents an efficient tool for quantity surveyors and any intervening actions are required to enhance its efficiency. In doing so, a team of surveyors interviewed and then the soft system methodology was used as the research approach to depict the situation. This leads to the improvement needs and list of actions. Participants have prioritized working closely with top/senior management to design a proper report format; avoiding unnecessary adjustments and undue influence to reporting, and ensuring accurate data as the top three critical actions crucial for reliable cost reporting.

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