Size and sign of time savings

INTRODUCTION The conventional approach in the U.K. has been to value all travel time changes at a constant rate regardless of their size or direction. This ‘constant unit value’ approach was supported by the 1980-86 UK DoT Value of Time Study (MVA/ITS/TSU, 1987). However, there has always remained a vocal body of opinion critical of this approach (see Welch and Williams, 1997, for references and discussion). Some of the main objections have been the following: i. small amounts of time are less useful than large amounts; ii. small time savings (or losses) might not be noticed by travellers and any that are not noticed cannot be valued by those affected and so should not be valued by society; iii. small time savings are said to often account for a large proportion of scheme benefits, so that small errors in measurement might mean that the scheme is really of no benefit to anyone; iv. allowing small time savings to have ‘full’ value is said to inflate the measured total of benefits and so lead to schemes (often road schemes) being wrongly found to have sufficient net benefit to justify implementation; v. time savings are less highly valued than are time losses, according to surveys, and so should have a lower unit value when evaluating schemes. Both aspects relate to the possible non-constancy of the value of time for a given journey made for a given purpose (clearly, it is much less controversial, and indeed standard practice, to allow for variation by purpose and traveller type). The practical difficulties are twofold. On the one hand, it is difficult to overcome the lay reaction that small time savings have little or no value, as well as the feeling that losses are more important than gains. On the other hand, if these points have any empirical relevance, they cause major problems for the cost-benefit calculus, as losses and gains will not cancel out, and time savings cannot be directly aggregated. Although they do not recommend that values differentiated by size and sign should be used for appraisal, the HCG/Accent (1999) Report (AHCG) notes that [p 259] "For any level of variation around the original journey time, gains (savings) are valued less than losses. For non-work related journeys, a time savings of five minutes has negligible value." A recent paper by Gunn (2001) notes that corroborative results are available from a reanalysis of the 1988 Dutch value of Time study. For reasons which will be carefully rehearsed in this paper, we do not believe that the conclusion on the differences between gains and losses is safe. This is based on an extensive re-analysis of the AHCG data. We have found it harder to reach a conclusion on the issue of small time savings, we agree with AHCG that their data undoubtedly implies a lower valuation: we have some concerns, nonetheless, as to the interpretation which should be placed on this

Stochastic Gravitational Wave Measurements with Bar Detectors: Dependence of Response on Detector Orientation

The response of a cross-correlation measurement to an isotropic stochastic gravitational-wave background depends on the observing geometry via the overlap reduction function. If one of the detectors being correlated is a resonant bar whose orientation can be changed, the response to stochastic gravitational waves can be modulated. I derive the general form of this modulation as a function of azimuth, both in the zero-frequency limit and at arbitrary frequencies. Comparisons are made between pairs of nearby detectors, such as LIGO Livingston-ALLEGRO, Virgo-AURIGA, Virgo-NAUTILUS, and EXPLORER-AURIGA, with which stochastic cross-correlation measurements are currently being performed, planned, or considered.Comment: 17 pages, REVTeX (uses rcs, amsmath, hyperref, and graphicx style files), 4 figures (8 eps image files

A STATISTICAL ANALYSIS OF THE IRISH ELECTORAL REGISTER AND ITS USE FOR POPULATION ESTIMATION AND SAMPLE SURVEYS. General Research Series Paper No. 130, July 1986

The Electoral Register’s prime purpose is to serve as a list of those persons in tile State who are eligible to vote in national and local elections. Apart from this function it is also used by researchers in the social sciences for other purposes, as it is tile only regularly updated list of the adult population which is readily available. In particular, it has been used as a sampling frame for social surveys and as an indicator of population levels. The accuracy of the Register is, therefore, of interest to researchers

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 ($\dot{M}_{out}$/$\dot{M}_{acc}$). 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 $\sim$ 20$^{\circ}$. The aim here is to further investigate the properties of ISO-ChaI 217, the morphology and kinematics of its outflow, and to better constrain ($\dot{M}_{out}$/$\dot{M}_{acc}$). The outflow is spatially resolved in the $[SII]\lambda \lambda 6716,6731$ lines and is detected out to $\sim$ 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($\dot{M}_{acc}$) [M$_{sun}$/yr]= -10.6 $\pm$ 0.4. As it was not possible to measure the effect of extinction on the ISO-ChaI 217 outflow $\dot{M}_{out}$ was derived for a range of values of A$_{v}$, up to a value of A$_{v}$ = 2.5 mag estimated for the source extinction. The logarithm of the mass outflow ($\dot{M}_{out}$) was estimated in the range -11.7 to -11.1 for both jets combined. Thus $\dot{M}_{out}$/$\dot{M}_{acc}$ [\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$\alpha$ line show that the bulk of the H I emission comes from the accretion flow.Comment: accepted by Astronomy & Astrophysic