Greater Manchester PTE New Railway Station Demand Prediction Model

This paper reports on work that was initiated in February 1989 to develop a simple model that can accurately predict the usage of new stations in the Greater Manchester area. The starting point for this study was the work carried out by Moss in 1988 in which an attempt was made to develop a new station demand model based on patronage data for 9 of the 10 new stations that had been opened in Greater Manchester since 1984. In his research the main explanatory variable was the population within 1,000m and the sub-divisions 0-300m, 300-600m, 600-800m and 800-1,000m were also examined. Arbitrary dummy variables were studied to assess the effect of service frequency, car ownership, alternative routes and park and ride. The main finding was that population, on its own, did not appear to be an adequate explanatory variable. For example, Mills Hill was found to attract 7.9 times as many passengers per 1,000 households as Hag Fold. In other words, there was very large variation in the trip rates at these nine new stations, with a mean of 36.2 and a standard deviation of 22.4 daily trips per thousand households. An alternative approach is that developed in West Yorkshire based on multiple regression techniques (Preston, 1987). This model predicts the number of rail trips between two stations as a function of: (i) the population within 800 metres of the origin station, (ii) the proportion of that population in social classes I and II, (iii) the population between 800 metres and 2 kilometres of the origin station, (iv) the number of jobs within 800 metres of the destination station, (v) the generalised cost of rail, (vi) the generalised cost of competing modes (bus and car). This model is a form of direct demand model in that it forecasts the number of trips (T) between origin i and destination j by mode k (ie. Tijk). In this paper, we shall develop a simpler version of this model which will simply predict the number of trips from origin i by mode k (ie. Tik). We shall call this a trip end model. The West Yorkshire model (called the Aggregate Simultaneous Model - ASM) was calibrated for 39 existing stations based on patronage data collected in the early 1980s. In this work, we shall attempt to calibrate a similar model for 36 existing stations in Greater Manchester, based on patronage data collected in 1987/8. These stations are listed in Appendix 1. Of these stations 16 are on what we have termed the Oldham Loop, 9 are on the Bury Line, 9 are on the Altrincham Line and the remaining 2 are on the Buxton Line. It was felt that this sample was reasonably representative of Greater Manchester new stations although well used commuter stations may be unavoidably over represented due to the availability of patronage data which dictated at data set. In developing a new station model for Greater Manchester, we have borne in mind comments made about Moss's earlier work by Greater Manchester PTE, Greater Manchester Transportation Unit, Manchester City Council and British Rail, Provincial (Midland) and in particular the consideration of existing trip patterns, especially to central Manchester. Whilst we encountered difficulties in obtaining relevant data, we were able to explicitly incorporate a number of other points. Our work will be based on multiple regression and will be able to examine the effect of distance, frequency and car ownership directly. Use will be made of 0-800m and 800m - 2km populations (rather than households within 1km), adjusted to take into account overlapping catchment areas. Figure 1 shows the zoning scheme used. Having dealt with the background to this study, the rest of the report will be as follows: - in section 2 we outline the data sought and made available for our study; - in section 3 we describe the process of calibrating a simple trip end model; - in section 4 our simple trip end model is developed further and in greater depth with the aim of maximising the goodness of fit; - in section 5 we develop a more generalised framework; - in section 6 we calibrate a simple trip end model for walk access patrons; -in section 7 we comment on the criteria of model choice, discuss statistical problems related to cross-sectional data and summarise our findings

CHANDRA Observations of X-ray Jet Structure on kpc to Mpc Scales

With its exquisite spatial resolution of better than 0.5 arcsecond, the Chandra observatory is uniquely capable of resolving and studying the spatial structure of extragalactic X-ray jets on scales of a few to a few hundred kilo-parsec. Our analyses of four recent Chandra images of quasar jets interpret the X-ray emission as inverse Compton scattering of high energy electrons on the cosmic microwave background. We infer that these jets are in bulk relativistic motion, carrying kinetic powers upwards of 10^46 ergs/s to distances of hundreds of kpc, with very high efficiency.Comment: 4 pages, 3 figures, to be published in the proceedings of the Bologna jet workshop, "The Physics of Relativistic Jets in the CHANDRA and XMM Era.

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

The Translog Costs Function Applied to European Railways.

This paper expands the exploratory analysis undertaken by Vigoroux-Steck (1990), who used statistical cost techniques, in conjunction with UIC published data, to estimate cost functions for 13 Western European railway operations. Four improvements have been made to Steck's work. Firstly, the data has been up-dated from 1987 to 1990 and re-indexed to incorporate the most recent information on international prices. Secondly, consistency is introduced into the Returns to Scale and Density measures by including all relevant estimated parameter values. Thirdly, we constrain the repssion model to insure linear homogeneity of degree one in factor prices. Fourthly, we attempt to reduce statistical problems by redefining variables around the sample mean (although there is further work to be undertaken in this respect). Three further amendments were undertaken with limited success. Attempts to introduce a more complex treatment of technological change led to implausible returns to scale. Attempts to re-define the returns to density measure by using a length of line variable rather than a density (train kilometres divided by length of line) variable also led to some implausible results. A re-definition of Steck's returns to density measure gave more plausible results. Despite these statistical problems, some common results do come hmgh. In particular, it appears that Western Europe's largest railways exhibit decreasing returns to scale and increasing returns to density. This does suggest that some European railways are operating beyond the point of maximum efficient scale and re-organisation into smaller units may be sensible. Our findings are less robust on how small these units should be. Railways with less than 3,000 km of route may be below the minimum efficient scale. Another important finding is that some Western Europe railways do exhibit diseconomies of density most notably those of Switzerland and the Netherlands. Proposed expansion of infrastructure in these countries may be sensible. Lastly, in terms of an index of managerial efficiency, we find that the railway of Sweden is a consistently high performer and those of Austria and Belgium poor performers

Cuprous hydrometallurgy: Part VIII. Solvent extraction and recovery of copper(I) chloride with organic nitriles from an iron(III), copper(II) chloride, two-step oxidative leach of chalcopyrite concentrate

Water-immiscible organic nitriles selectively extract copper(I) chloride as CuCl from aqueous chloride solutions. The distribution coefficients for the extraction of metal chlorides are in the order Ni2+ ⪡ Fe2+ < Na+ < Cu2+ ≈ Co2+ < Cu+ ⩽ Fe3+. The equilibrium Cu2+ + Fe2+ ⇌ Cu+ + Fe3+ lies strongly to the right in nitrile solutions containing a small amount of water. When volatile nitriles containing some water are used as extractants, CuCl may be recovered from the organic phase by stripping the solvent with steam. Pure CuCl, suitable for reduction to electrolytic-grade copper, is precipitated from the residual aqueous phase. A process is demonstrated for the recovery of pure CuCl from chalcopyrite concentrate, in which a two-stage, iron(III), copper(II) chloride leach is used to maximize the amount of CuCl relative to CuCl2 formed in solution