Edinburgh Napier University

About: Edinburgh Napier University is a education organization based out in Edinburgh, United Kingdom. It is known for research contribution in the topics: Population & Health care. The organization has 2665 authors who have published 6859 publications receiving 175272 citations.

A probit-based stochastic user equilibrium assignment model

Abstract: Stochastic methods of traffic assignment have received much less attention in the literature than those based on deterministic user equilibrium (UE). The two best known methods for stochastic assignment are those of Burrell and Dial, both of which have certain weaknesses which have limited their usefulness. Burrell's is a Monte Carlo method, whilst Dial's logit method takes no account of the correlation, or overlap,between alternative routes. This paper describes, firstly, a probit stochastic method (SAM) which does not suffer from these weaknesses and which does not require path enumeration. While SAM has a different route-finding methodology to Burrell, it is shown that assigned flows are similar. The paper then goes on to show how, by incorporating capacity restraint (in the form of link-based cost-flow functions) into this stochastic loading method, a new stochastic user equilibrium (SUE) model can be developed. The SUE problem can be expressed as a mathematical programming problem, and its solution found by an iterative search procedure similar to that of the Frank-Wolfe algorithm commonly used to solve the UE problem. The method is made practicable because quantities calculated during the stochastic loading process make the SUE objective function easy to compute. As a consequence, at each iteration, the optimal step length along the search direction can be estimated using a simple interpolation method. The algorithm is demonstrated by applying it successfully to a number of test problems, in which the algorithm shows good behaviour. It is shown that, as the values of parameters describing the variability and degree of capacity restraint are varied, the SUE solution moves smoothly between the UE and pure stochastic solutions.

Avoiding the 'McJobs': unemployed job seekers and attitudes to service work

Abstract: Service employment plays an increasingly important role in the UK economy. However, it has been suggested that some forms of service work are unattractive for many unemployed job seekers, and parti...

Toll-like receptor expression on classic and pro-inflammatory blood monocytes after acute exercise in humans

Abstract: Monocytes are a heterogeneous group of cells, the relative distribution of which change in peripheral blood following a strenuous bout of aerobic exercise. Monocyte subtypes can be identified in blood based on the cell surface expression of CD14 and CD16: classic (CD14(++bright)/CD16(-negative)) and the CD16(+dim) (CD14(++bright)/CD16(+dim)) and CD16(++bright) (CD14(+dim)/CD16(++bright)) pro-inflammatory subtypes. Whole monocyte population changes in TLR2, TLR4 and HLA.DR expression have previously been documented after acute exercise without accounting for relative changes in monocyte subpopulations, therefore, this study examined their expression on classic and pro-inflammatory monocyte subsets following 45min of treadmill running at 75% VO(2max). Mononuclear cells isolated from the peripheral blood of moderately trained male subjects (n=15) before (PRE), immediately after (POST) and 1h after (1H) exercise were assessed for TLR2, TLR4 and HLA.DR expression on blood monocytes and their subpopulations using three-colour flow cytometry. Compared to PRE, the proportion of CD14+/CD16+ monocytes was 27% greater POST and 49% less at 1H and was associated with changes in the CD16(++bright) pro-inflammatory subtype (p 0.05). We conclude that acute exercise causes localised changes in TLR2, TLR4 and HLA.DR expression within specific blood monocyte subpopulations, and could therefore be occurring at the cellular level. Such alterations might have significant implications for modulation of post-exercise immune surveillance.

Mutual-Coupling Isolation Using Embedded Metamaterial EM Bandgap Decoupling Slab for Densely Packed Array Antennas

Abstract: This article presents a unique technique to enhance isolation between transmit/receive radiating elements in densely packed array antenna by embedding a metamaterial (MTM) electromagnetic bandgap (EMBG) structure in the space between the radiating elements to suppress surface currents that would otherwise contribute towards mutual coupling between the array elements. The proposed MTM-EMBG structure is a cross-shaped microstrip transmission line on which are imprinted two outward facing E-shaped slits. Unlike other MTM structures there is no short-circuit grounding using via-holes. With this approach, the maximum measured mutual coupling achieved is -60 dB @ 9.18 GHz between the transmit patches (#1 & #2) and receive patches (#3 & #4) in a four-element array antenna. Across the antenna’s measured operating frequency range of 9.12 to 9.96 GHz, the minimum measured isolation between each element of the array is 34.2 dB @ 9.48 GHz, and there is no degradation in radiation patterns. The average measured isolation over this frequency range is 47 dB. The results presented confirm the proposed technique is suitable in applications such as synthetic aperture radar (SAR) and multiple-input multiple-output (MIMO) systems.