9,544 research outputs found
Rolling stock quality - Improvements and user willingness to pay.
This study has estimated monetary valuations of various types of rolling stock and stock related attributes in relation to each other. It has used a combination of Revealed Preference (RP) and Stated Preference (SP) methods. The estimated monetary valuations of different types of rolling stock do not vary greatly and this contrasts with most of the previous quantitative research findings in this area.
The largest valuation of one stock type in relation to another was 39 pence per single trip for the comparison of Wessex electrics and Sprinters. This valuation is equivalent to 4.3% of the average fare paid.
With regard to specific rolling stock attributes, this study has examined seating comfort, seating layout, ride quality, ambience, ventilation and noise. The most important attributes were found to be seating comfort, ride quality and ambience. The largest valuation obtained for seat comfort differences was 17 pence per single trip for the comparison of Networkers and Sprinters. This is equivalent to 1.9% of the average single fare. The corresponding figure for ride quality was 13 pence for the comparison of Wessex electrics and Sprinters and for ambience it was 10 pence for the comparison of Networkers and Sprinters. The maximum differences between stock types in terms of seating layout, ventilation and noise were all valued at less than five pence.
The results can be generalised to stock types not covered in this research by obtaining ratings on a ten point scale of the relevant train types or specific rolling stock attributes and entering these into the estimated model
Direct Demand Models of Air Travel: A Novel Approach to the Analysis of Stated Preference Data
This paper uses what has been termed the direct demand approach to obtain elasticity estimates from discrete choice Stated Preference data. The Stated Preference data relates to business travellers' choices between air and rail. The direct demand methodology is outlined and some potential advantages over the conventional disaggregate logit model are discussed. However, further research regarding the relative merits of the two approaches is recommended. The direct demand model is developed to explain variations in the demand for air travel as a function of variations in air headway and cost and in train journey time, frequency, interchange and cost. Relatively little has previously been published about the interaction between rail and air and the elasticities and variation in them which have been estimated are generally plausible. In particular, the results show that large improvements in rail journey times can have a very substantial impact on the demand for air travel and that the rail journey time cross-elasticity depends on satisfying a three hour journey time threshold
Binary companions of evolved stars in APOGEE DR14: Orbital circularization
Short-period binary star systems dissipate orbital energy through tidal
interactions that lead to tighter, more circular orbits. When at least one star
in a binary has evolved off of the main sequence, orbital circularization
occurs for longer-period (~100 day) systems. Past work by (Verbunt & Phinney
1995) has shown that the orbital parameters and the circularization periods of
a small sample of binary stars with evolved-star members can be understood
within the context of standard tidal circularization theory. Using a sample of
binaries with subgiant, giant, and red clump star members that is nearly an
order of magnitude larger, we reexamine predictions for tidal circularization
of binary stars with evolved members. We confirm that systems predicted by
equilibrium-tide theory to have circular orbits generally have negligible
measured eccentricities. The circularization period is correlated with the
surface gravity (i.e. size) of the evolved member, indicating that the
circularization timescale must be shorter than the evolutionary timescale along
the giant branch. A few exceptions to the conclusions above are mentioned in
the discussion: Some of these exceptions are likely systems in which the
spectrum of the secondary biases the radial velocity measurements, but four
appear to be genuine, short-period, moderate-eccentricity systems.Comment: 13 pages, 6 figures; comments welcom
Characterisation of nicotine receptors on human peripheral blood mononuclear cells (PBMC)
“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1007/s00011-008-8171-xAim and objective: The aim of the work was to characterise the nAChRs on human PBMC. Method: PBMC were isolated from human blood buffy coats provided by the blood transfusion service and were used for radioligand binding studies with [3H]-nicotine. RT-PCR experiments were used to determine nAChR subunit expression while immunoblotting experiments were used to confirm that nAChR subunits identified by RT-PCR were translated into protein. Results: Binding studies suggested the presence of one binding site for (-)- nicotine on human peripheral blood lymphocytes. Competition studies showed that only (-)- nicotine, epibatidine and α-bungarotoxin, displaced radiolabelled nicotine from cells. RT-PCR studies demonstrated mRNA for α4, α5, α7, β1 and β2 nAChRs subunits in PBMC. Expression of mRNA for the a5 subunit of nAChR was observed in all lymphocyte samples tested. In contrast, the expression pattern of mRNAs for α4, α7, β1, and β2 mRNAs subunits of nAChRs, varied between samples. Western blot analysis showed that protein for α4, α5, and α7 and β2 nAChR subunits was expressed in most, but not all of the PBMC samples tested but some of the bands obtained were faint. Conclusion: The results obtained suggest that human PBMC contain nAChRs containing α4β2, α4β2α5, and/or α7 subunits.Peer reviewe
What bandwidth do I need for my image?
Computer representations of real numbers are necessarily discrete, with some
finite resolution, discreteness, quantization, or minimum representable
difference. We perform astrometric and photometric measurements on stars and
co-add multiple observations of faint sources to demonstrate that essentially
all of the scientific information in an optical astronomical image can be
preserved or transmitted when the minimum representable difference is a factor
of two finer than the root-variance of the per-pixel noise. Adopting a
representation this coarse reduces bandwidth for data acquisition,
transmission, or storage, or permits better use of the system dynamic range,
without sacrificing any information for down-stream data analysis, including
information on sources fainter than the minimum representable difference
itself.Comment: submitted to PAS
Accretion-ejection connection in the young brown dwarf candidate ISO-Cha1 217
As the number of observed brown dwarf outflows is growing it is important to
investigate how these outflows compare to the well studied jets from young
stellar objects. A key point of comparison is the relationship between outflow
and accretion activity and in particular the ratio between the mass outflow and
accretion rates (/). The brown dwarf candidate
ISO-ChaI 217 was discovered by our group, as part of a spectro-astrometric
study of brown dwarfs, to be driving an asymmetric outflow with the
blue-shifted lobe having a position angle of 20. The aim here
is to further investigate the properties of ISO-ChaI 217, the morphology and
kinematics of its outflow, and to better constrain
(/). The outflow is spatially resolved in the
lines and is detected out to 1\farcs6
in the blue-shifted lobe and ~ 1" in the red-shifted lobe. The asymmetry
between the two lobes is confirmed although the velocity asymmetry is less
pronounced with respect to our previous study. Using thirteen different
accretion tracers we measure log() [M/yr]= -10.6
0.4. As it was not possible to measure the effect of extinction on the ISO-ChaI
217 outflow was derived for a range of values of A, up to
a value of A = 2.5 mag estimated for the source extinction. The logarithm
of the mass outflow () was estimated in the range -11.7 to -11.1
for both jets combined. Thus / [\Msun/yr] lies
below the maximum value predicted by magneto-centrifugal jet launching models.
Finally, both model fitting of the Balmer decrements and spectro-astrometric
analysis of the H line show that the bulk of the H I emission comes
from the accretion flow.Comment: accepted by Astronomy & Astrophysic
A survey of the reasons for the likes and dislikes of first grade children in the Row, Peterson Basal Reader, Round About.
Thesis (Ed.M.)--Boston Universit
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