457 research outputs found
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Effects of blood withdrawal and reinfusion on biomarkers of erythropoiesis in humans: Implications for anti-doping strategies
To discriminate autologous blood doping procedures from normal conditions, we examined the hematological response to blood withdrawal and reinfusion. We found that biomarkers of erythropoiesis are primarily affected in the anemic period. Therefore, individual variations in [Hb] exceeding 15% between samples obtained shortly before any major competition would be indicative of autologous blood manipulation
DIFFERENCES IN JUMPING PERFORMANCE OF CHILDREN FROM DIFFERENT SPORTS
The ability of high rate of force development is crucial in many high power sports. The aim of this study was to examine the possible differences in jumping skills of children participating in sports with different demands of leg strength, in order to investigate if specific training influenced different jump performances. 175 children from four different sports participated. The subjects performed squat jumps; counter movement jumps and drop jumps from 0.2 m and 0.4 m. The study showed that the nature of the sport has influence on the performance of drop jumping ability on children, though natural selection may also have an influence
Developing a framework for mobile payments integration
This paper derives a theoretical framework for consideration of both the technologically driven dimensions of mobile payment solutions, and the associated value proposition for customers. Banks promote traditional payment instruments whose value proposition is the management of risk for both consumers and merchants. These instruments are centralised, costly and lack decision support functionality. The ubiquity of the mobile phone has provided a decentralised platform for managing payment processes in a new way, but the value proposition for customers has yet to be elaborated clearly. This inertia has stalled the design of sustainable revenue models for a mobile payments ecosystem. Merchants and consumers in the meantime are being seduced by the convenience of on-line and mobile payment solutions. Adopting the purchase and payment process as the unit of analysis, the current mobile payment landscape is reviewed with respect to the creation and consumption of customer value. From this analysis, a framework is derived juxtaposing customer value, related to what is being paid for, with payment integration, related to how payments are being made. The framework provides a theoretical and practical basis for considering the contribution of mobile technologies to the payment industry. The framework is then used to describe the components of a mobile payments pilot project being run on a trial population of 250 students on a campus in Ireland. In this manner, weaknesses in the value proposition for consumers and merchants were highlighted. Limitations of the framework as a research tool are also discussed
Reduction of nickel oxide particles by hydrogen studied in an environmental TEM
In situ reduction of nickel oxide (NiO) particles is performed under 1.3mbar of hydrogen gas (H2) in an environmental transmission electron microscope (ETEM). Images, diffraction patterns and electron energy-loss spectra (EELS) are acquired to monitor the structural and chemical evolution of the system during reduction, whilst increasing the temperature. Ni nucleation on NiO is either observed to be epitaxial or to involve the formation of randomly oriented grains. The growth of Ni crystallites and the movement of interfaces result in the formation of pores within the NiO grains to accommodate the volume shrinkage associated with the reduction. Densification is then observed when the sample is nearly fully reduced. The reaction kinetics is obtained using EELS by monitoring changes in the shapes of the Ni L2,3 white lines. The activation energy for NiO reduction is calculated from the EELS data using both a physical model-fitting technique and a model-independent method. The results of the model-fitting procedure suggest that the reaction is described by Avrami models (whereby the growth and impingement of Ni domains control the reaction), in agreement with the ETEM observation
A new methodology to simulate subglacial deformation of water-saturated granular material
The dynamics of glaciers are to a large degree governed by processes
operating at the ice–bed interface, and one of the primary
mechanisms of glacier flow over soft unconsolidated sediments is
subglacial deformation. However, it has proven difficult to
constrain the mechanical response of subglacial sediment to the
shear stress of an overriding glacier. In this study, we present
a new methodology designed to simulate subglacial deformation using
a coupled numerical model for computational experiments on
grain-fluid mixtures. The granular phase is simulated on a per-grain
basis by the discrete element method. The pore water is modeled as
a compressible Newtonian fluid without inertia. The numerical
approach allows close monitoring of the internal behavior under
a range of conditions.
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Our computational experiments support the findings of previous studies
where the rheology of a slowly deforming water-saturated granular bed in the
steady state generally conforms to the rate-independent plastic rheology.
Before this so-called critical state, deformation is in many cases accompanied
by volumetric changes as grain rearrangement in active shear zones changes the
local porosity. For previously consolidated beds porosity
increases can cause local pore-pressure decline, dependent on till
permeability and shear rate. We observe that the pore-water pressure reduction
strengthens inter-granular contacts, which results in increased shear strength
of the granular material. In contrast, weakening takes place when shear
deformation causes consolidation of dilated sediments or during rapid fabric
development. Both processes of strengthening and weakening depend inversely on
the sediment permeability and are transient phenomena tied to the porosity
changes during the early stages of shear.
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We find that the transient strengthening and weakening in turn influences the
distribution of shear strain in the granular bed. Dilatant strengthening has
the ability to distribute strain during early deformation to large depths, if
sediment dilatancy causes the water pressure at the ice–bed interface to
decline. Oppositely, if the ice–bed interface is hydrologically stable the
strengthening process is minimal and instead causes shallow deformation. The
depth of deformation in subglacial beds thus seems to be governed by not only
local grain and pore-water feedbacks but also larger-scale hydrological
properties at the ice base
A web of stakeholders and strategies: A case of broadband diffusion in South Korea
When a new technology is launched, its diffusion becomes an issue of importance. There are various stakeholders that influence diffusion. The question that remains to be determined is their identification and roles. This paper outlines how the strategies pursued by a government acting as the key stakeholder affected the diffusion of a new technology. The analysis is based on a theoretical framework derived from innovation diffusion and stakeholder theories. The empirical evidence comes from a study of broadband development in South Korea. A web of stakeholders and strategies is drawn in order to identify the major stakeholders involved and highlight their relations. The case of South Korea offers implications for other countries that are pursuing broadband diffusion strategies
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