6,375 research outputs found
Evaluating the long term impacts of transport policy: the case of passenger rail privatisation in Great Britain
No full textBritain’s national rail system was ‘privatised’ as a result of the 1993 Railways Act, with most of the organisational and ownership changes implemented by 1997. This thesis examines the long term impacts of the privatisation initiative on the passenger rail service. A key issue when examining long term changes is that of the counterfactual – what would have happened if the changes had not occurred? A simple econometric model of the demand for passenger rail services was developed and used in conjunction with extrapolative methods for key variables such as fares, train kms and GDP to determine demand-side counterfactuals. Extrapolative methods were also used to determine counterfactual infrastructure and train operation costs. Although since privatisation rail demand has grown strongly, the analysis indicates that transitional disruptions suppressed demand by around 4% over a prolonged period (1994/95 to 2005/6), whilst the Hatfield accident reduced demand by about 5%, albeit over a short period (2000/1 to 2005/6). A welfare analysis indicates that although consumers gained as a result of privatisation, for most years this has been offset by increases in costs. An exception is provided by the two years immediately before the Hatfield accident. Overall the loss in welfare since the reforms were introduced far exceeds the net receipts from the sale of rail businesses. It is found that although the reforms have had advantages in terms of lower fares and better service levels than otherwise would have been the case, this has been offset by adverse transitional effects and high costs, which in turn may be linked with higher transaction costs
Glitch Collective
No full textExtent : 15 minutes This event was curated by Tristan Louth Robins as part of the Tyndall Series ; the event was promoted by Luke Altmann
Large-eddy simulation of dispersion: comparison between elevated source and ground level source
No full textLarge-eddy simulation (LES) is used to calculate the concentration fluctuations of passive plumes from an elevated source (ES) and a ground-level source (GLS) in a turbulent boundary layer over a rough wall. The mean concentration, relative fluctuations and spectra are found to be in good agreement with the wind-tunnel measurements for both ES and GLS. In particular, the calculated relative fluctuation level for GLS is quite satisfactory, suggesting that the LES is reliable and the calculated instantaneous data can be used for further post-processing. Animations are shown of the meandering of the plumes, which is one of the main features to the numerical simulations. Extreme value theory (EVT), in the form of the generalized Pareto distribution (GPD), is applied to model the upper tail of the probability density function of the concentration time series collected at many typical locations for GLS and ES from both LES and experiments. The relative maxima (defined as maximum concentration normalized by the local mean concentration) and return levels estimated from the numerical data are in good agreement with those from the experimental data. The relative maxima can be larger than 50. The success of the comparisons suggests that we can achieve significant insight into the physics of dispersion in turbulent flows by combining LES and EVT
Atractodenchelys phrix Robins
No full textAtractodenchelys phrix Robins an Robins 1970 (Fig. 3 I) Material examined. One specimen, 300.0 mm TL: MNRJ 26829 (1, 300.0 mm), T, E- 534. Distribution. Atractodenchelys phrix is being reported by the first time in the WSA. It was described from the eastern Caribbean (11 º 36 ’ N, 62 º 52 ’ W) and is also known from the western Caribbean Sea, the Atlantic Ocean north of Puerto Rico to the coast of Florida (Robins & Robins 1989).Published as part of Melo, Marcelo R. S., Nunan, Gustavo W. A., Braga, Adriana C. & Costa, Paulo A. S., 2009, The deep-sea Anguilliformes and Saccopharyngiformes (Teleostei: Elopomorpha) collected on the Brazilian continental slope, between 11 and 23 S, pp. 1-20 in Zootaxa 2234 on page 12, DOI: 10.5281/zenodo.19038
Modelling extreme concentration from a source in a turbulent flow over rough wall
No full textThe concentration fluctuations in passive plumes from an elevated and a groundlevel
source in a turbulent boundary layer over a rough wall were studied using
large eddy simulation and wind tunnel experiment. The predictions of statistics
up to second order moments were thereby validated. In addition, the trend of relative
fluctuations far downstream for a ground level source was estimated using
dimensional analysis. The techniques of extreme value theory were then applied
to predict extreme concentrations by modelling the upper tail of the probability
density function of the concentration time series by the Generalised Pareto Distribution.
Data obtained from both the simulations and experiments were analysed in
this manner. The predicted maximum concentration (?0) normalized by the local
mean concentration (Cm) or by the local r.m.s of concentration fluctuation (crms),
was extensively investigated. Values for ?0/Cm and ?0/crms as large as 50 and 20
respectively were found for the elevated source and 10 and 15 respectively for the
ground-level source
An efficient algorithm for computing interventional distributions in latent variable causal models
No full textProbabilistic inference in graphical models is the task of computing marginal and conditional densities of interest from a factorized representation of a joint probability distribution. Inference algorithms such as variable elimination and belief propagation take advantage of constraints embedded in this factorization to compute such densities efficiently. In this paper, we propose an algorithm which computes interventional distributions in latent variable causal models represented by acyclic directed mixed graphs (ADMGs). To compute these distributions efficiently, we take advantage of a recursive factorization which generalizes the usual Markov factorization for DAGs and the more recent factorization for ADMGs. Our algorithm can be viewed as a generalization of variable elimination to the mixed graph case. We show our algorithm is exponential in the mixed graph generalization of tree width
The ladie's pocket magazine; vol. 1
No full textFront. con grab. xilPort. con grab. xil.: Zenaira & Alamede- from the novel of IpsiboeSign.: A-T(6), Y(5), B-S(6)Paginacion incompleta, ejemplar falto de
Parlement(s) et cours souveraines - 2024 - 2 : "Les robins et la Révolution"
No full textLa prochaine séance du séminaire "Parlement(s) et cours souveraines sous l'Ancien Régime" se tiendra le : Vendredi 26 avril 2024 (16h30-18h30) nous écouterons : Francesco Di Donato (Université de Naples), « Les robins et la Révolution française ». Seront ses répondants : Sonia Scognamiglia (Université de Naples) et Frédéric Bidouze (Université de Pau et des pays de l’Adour) Le séminaire se tiendra salle Collinet de l'Institut d'Histoire du Droit-Jean Gaudemet, 4 rue Valette, 75005 Paris, esc..
Conversion of vinylsilanes to vinyl halides with xenon difluoride and metal halides. A versatile new route to 5-(2-halovinyl)pyrimidine nucleosides
No full textAddition of a protected 5-(2-trimethylsilylvinyl)uracil nucleoside to suspensions of xenon difluoride and alkali metal halides in benzene (or other solvents) resulted in rapid formation of the corresponding 5-(2-halovinyl)uracil products (E-isomer predominating). © 1990
- …
