Milton Keynes: an outline cost-benefit study

This is a preliminary survey of some of the factors which would need to be investigated in the design and cost-benefit analysis of alternative transport systems for Milton Keynes. It outlines the framework within which further work can be developed and provides some order-of-magnitude estimates for basic elements in the transport cost-benefit equations

Aristotle on Mind and the Science of Nature

On the basis of two premises to which he is committed, it would seem that Aristotle must be a “naturalist” about the investigation of the soul: 1. Natural things have both a material and a formal nature. 2. In the case of living things, their formal nature is their soul. This paper deals with a complication in the above inference. In De partibus animalium I 1, Aristotle insists that the natural scientist should not speak of all soul, since not all of the soul is a nature, though one or more parts of it is (641b8–9). In this paper I argue that this claim is consistent with everything he says in the De anima about the investigation of reason, and is a consequence of his views about the methodological norms of natural science. Aristotle is a naturalist when it comes to those parts of the soul human beings share with other animals, but his views about the mind are much more complicated

Milton Keynes - preliminary estimates of regional traffic flows in 1981

The Milton Keynes Development Corporation and their planning consultants have asked the College Transport Group to investigate the scale of likely regional traffic flows into and out of Milton Keynes. At this stage the emphasis is on providing information for the preparation of a Master Plan for the city itself, rather than detailed traffic estimates for planning transport systems in the surrounding region. Population estimates for 1981 have been obtained from County Councils for areas within a 20 mile radius of the new city, and the proportions attracted to Milton Keynes for work and shopping assessed using gravity model techniques. Separate estimates have been made of work journeys from the city to regional employment and to London. Possible upper and lower limits to these forecasts are included to account for many uncertainties in the absolute and relative growth of population, employment and shopping opportunities in the city itself and in the surrounding region. The results are presented as traffic flews into and out of octant sectors around the city. Flows to the east are greater than to the west with work trip flows of the order of 2,500 person trips each way in the most heavily loaded sectors. A 1981 city population of 150,000 is likely to produce at least 1,500 daily commuters to London using the fast rail service, with an additional 200 commuters from the region using Milton Keynes railway station

The Density of Lyman-alpha Emitters at Very High Redshift

We describe narrowband and spectroscopic searches for emission-line star forming galaxies in the redshift range 3 to 6 with the 10 m Keck II Telescope. These searches yield a substantial population of objects with only a single strong (equivalent width >> 100 Angstrom) emission line, lying in the 4000 - 10,000 Angstrom range. Spectra of the objects found in narrowband-selected samples at lambda ~5390 Angstroms and ~6741 Angstroms show that these very high equivalent width emission lines are generally redshifted Lyman alpha 1216 Angstrom at z~3.4 and 4.5. The density of these emitters above the 5 sigma detection limit of 1.5 e-17 ergs/cm^2/s is roughly 15,000 per square degree per unit redshift interval at both z~3.4 and 4.5. A complementary deeper (1 sigma \~1.0 e-18 ergs/cm^2/s) slit spectroscopic search covering a wide redshift range but a more limited spatial area (200 square arcminutes) shows such objects can be found over the redshift range 3 to 6, with the currently highest redshift detected being at z=5.64. The Lyman alpha flux distribution can be used to estimate a minimum star formation rate in the absence of reddening of roughly 0.01 solar masses/Mpc^3/year (H_0 = 65 km/s/Mpc and q_0 = 0.5). Corrections for reddening are likely to be no larger than a factor of two, since observed equivalent widths are close to the maximum values obtainable from ionization by a massive star population. Within the still significant uncertainties, the star formation rate from the Lyman alpha-selected sample is comparable to that of the color-break-selected samples at z~3, but may represent an increasing fraction of the total rates at higher redshifts. This higher-z population can be readily studied with large ground-based telescopes.Comment: 7 pages, 5 encapsulated figures; aastex, emulateapj, psfig and lscape style files. Separate gif files for 2 gray-scale images also available at http://www.ifa.hawaii.edu/faculty/hu/emitters.html . Added discussion of foreground contaminants. Updated discussion of comparison with external surveys (Sec. 5 and Fig. 5). Note: continuum break strength limits (Fig. 3 caption) are correct here -- published ApJL text has a sign erro

An Extremely Luminous Galaxy at z=5.74

We report the discovery of an extremely luminous galaxy lying at a redshift of z=5.74, SSA22-HCM1. The object was found in narrowband imaging of the SSA22 field using a 105 Angstrom bandpass filter centered at 8185 Angstroms during the course of the Hawaii narrowband survey using LRIS on the 10 m Keck II Telescope, and was identified by the equivalent width of the emission W_lambda(observed)=175 Angstroms, flux = 1.7 x 10^{-17} erg cm^{-2} s^{-1}). Comparison with broadband colors shows the presence of an extremely strong break (> 4.2 at the 2 sigma level) between the Z band above the line, where the AB magnitude is 25.5, and the R band below, where the object is no longer visible at a 2 sigma upper limit of 27.1 (AB mags). These properties are only consistent with this object's being a high-z Ly alpha emitter. A 10,800 s spectrum obtained with LRIS yields a redshift of 5.74. The object is similar in its continuum shape, line properties, and observed equivalent width to the z=5.60 galaxy, HDF 4-473.0, as recently described by Weymann et al. (1998), but is 2-3 times more luminous in the line and in the red continuum. For H_0 = 65 km s^{-1} Mpc^{-1} and q_0 = (0.02, 0.5) we would require star formation rates of around (40, 7) solar masses per year to produce the UV continuum in the absence of extinction.Comment: 5 pages, 4 figures, Latex with emulateapj style file; to appear in the Astrophysical Journal (Letters

SIPstone: Benchmarking SIP Server Performance

SIP-based Internet telephony systems need to be appropriately dimensioned, as the call and registration rate can reach several thousand requests a second. This draft proposes an initial simple set of metrics for evaluating and benchmarking the performance of SIP proxy, redirect and registrar servers. The benchmark SIPstone-A expresses a weighted average of these metrics

Galaxy Halo Masses from Galaxy-Galaxy Lensing

We present measurements of the extended dark halo profiles of bright early type galaxies at redshifts 0.1 to 0.9 obtained via galaxy-galaxy lensing analysis of images taken at the CFHT using the UH8K CCD mosaic camera. Six half degree fields were observed for a total of 2 hours each in I and V, resulting in catalogs containing ~20 000 galaxies per field. We used V-I color and I magnitude to select bright early type galaxies as the lens galaxies, yielding a sample of massive lenses with fairly well determined redshifts and absolute magnitudes M ~ M_* \pm 1. We paired these with faint galaxies lying at angular distances 20" to 60", corresponding to physical radii of 26 to 77 kpc (z = 0.1) and 105 to 315 kpc (z = 0.9), and computed the mean tangential shear of the faint galaxies. The shear falls off with radius roughly as expected for flat rotation curve halos. The shear values were weighted in proportion to the square root of the luminosity of the lens galaxy. Our results give a value for the average mean rotation velocity of an L_* galaxy halo at r~50-200 kpc of v_* = 238^{+27}_{-30} km per sec for a flat lambda (Omega_m0 = 0.3, Omega_l0 = 0.7) cosmology (v_* = 269^{+34}_{-39} km per sec for Einstein-de Sitter), and with little evidence for evolution with redshift. We compare to halo masses measured by other groups/techniques. We find a mass-to-light ratio of ~121\pm28h(r/100 kpc) and these halos constitute Omega ~0.04 \pm 0.01(r/100 kpc) of closure density. (abridged)Comment: Accepted for publication in ApJ (minor modifications) - 32 pages, 11 figs, 5 table