we propose to use a mathematical method based on stochastic comparisons of markov chains in order to derive performance indice bounds‎. ‎the main goal of this paper is to investigate various monotonicity properties of a single server retrial queue with first-come-first-served (fcfs) orbit and general retrial times using the stochastic ordering techniques‎.

In this work the effect of the γ-radiation dose on ageing of carbon black reinforced elastomeric materials was studied. The compounds based on natural rubber/chlorosulfonated rubber blend (NR/CSM) and butadiene acrylonitrile rubber/chlorosulfonated rubber blend (NBR/CSM) (50:50, w/w) with different loadings (0, 20, 40, 50, 60, 80 and 100 phr) of the filler with the average particle size of 40 n...

Rammed earth (RE) is attracting renewed interest throughout the world thanks to its "green" characteristics in the context of sustainable building. In this study, the ageing effects on RE material are studied on the walls which have been constructed and exposed for 22 years to natural weathering. First, mechanical characteristics of the "old" walls were determined by two approaches: in-situ dyn...

Associative memory deficits are pervasive with age. Memory for complex pictures, however, also seems to require the association of several scene elements into one representation, but picture memory is often age-invariant. We speculated that the natural relationships contained in pictures may explain this distinction and that memory for scenes with unusual novel relationships would be affected w...

Cognitive impairment is a well-recognised and cardinal feature of schizophrenia (Keefe 2007). Given the biological effects of ageing on the brain, it is important to consider the cognitive manifestations of schizophrenia in the context of ageing. Significant issues include the natural history of cognitive dysfunction over the lifespan, its progression to dementia, and the temporal relationship ...

Hepatitis C virus (HCV) infection is highly prevalent in injecting drug users across Europe, with national infection rates for this group ranging from 18% to 80%. However, infected individuals often show no noticeable symptoms, and many are unaware that they are carrying the virus, leading to it being referred to as a ‘hidden’ epidemic. Injecting opioid users in Europe constitute an ageing popu...

The long-term reliability of tidal turbines is critical if these structures are to be cost effective. Optimized design requires a combination of material durability models and structural analyses. Composites are a natural choice for turbine blades, but there are few data available to predict material behaviour under coupled environmental and cycling loading. The present study addresses this pro...

Introduction Tissue glycation, that occurs naturally through ageing and can be sometimes accelerated by disease such as diabetes mellitus, is clinically claimed to have induced irregular collagen alignment and increased collagen fibril density in patients [1]. This hence increases tissue stiffness and leads to plantar injury, i.e. ulcer. In the USA, 85% of all non-traumatic amputations in diabe...

Evolutionary theories of aging predict that fitness-related traits, including reproductive performance, will senesce because the strength of selection declines with age. Sexual selection theory predicts, however, that male reproductive performance (especially sexual advertisement) will increase with age. In both bodies of theory, diet should mediate age-dependent changes in reproductive perform...

Although speech is a highly natural mode of communication, building robust and usable speech-based interfaces is still a challenge, even if the target user group is restricted to younger users. When designing for older users, there are added complications due to cognitive, physiological, and anatomical ageing. Users may also find it difficult to adapt to the interaction style required by the sp...