Early versus late type galaxies in compact groups

We find a strong correlation between the effective radius of the largest early-type galaxies in compact groups of galaxies and the velocity dispersion of the groups. The lack of a similar correlation for late type galaxies is supportive of the so called second generation merging scenario which predicts that ellipticals should dominate the internal dynamics of the groups, while late-type galaxies are mainly recent interlopers which are still in an early stage of interaction with the group potential.Comment: Astron. Nachr., IN PRES

The untold standards of living story : the GDP value of twentieth century health improvements in developed economies

Economists are aware that conventional measures of national income do not capture everything that is important to individuals. In particular, the value of huge improvments in health over the twentieth century has gone uncalculated. Usher (1980) and Nordhaus (2002) have emphasised the virtues of including mortality improvments in some form of extended national income measure. This paper therefore sets out a methodology that can be used to calculate the value of mortality and morbidity improvements. The results indicate that health improvements in developed economies have been worth at least $1 trillion. As such not accounting for historical health gains leads to a significant underestimate of improvements in standards of living and economic development

Predicting Student Achievement In Intermediate University Economics From Principles Assessments

This study investigates how first year Principles of Economics courses assessment items predict achievement in post principles economics courses. Of particular interest is how achievement in different assessment forms (assignments, multiple choice questions, and constructed response questions) predicts future performance. I use assessment data compiled from principles and post principles economics classes at the University of Canterbury from 2002-2008. I also control for performance in first year mathematics, statistics, accountancy and management. I find that constructed response questions particularly in the end of semester final exam generally contain more predictive power than multiple choice questions or the term test constructed response items.Principles of Economics Assessment; Multiple Choice; Constructed Response; Free Response; Essay

Observational properties of compact groups of galaxies

Compact groups are small, relatively isolated, systems of galaxies with projected separations comparable to the diameters of the galaxies themselves. Two well-known examples are Stephan's Quintet (Stephan, 1877) and Seyfert's Sextet (Seyfert 1948a,b). In groups such as these, the apparent space density of galaxies approaches 10(exp 6) Mpc(sub -3), denser even than the cores of rich clusters. The apparent unlikeliness of the chance occurrence of such tight groupings lead Ambartsumyan (1958, 1975) to conclude that compact groups must be physically dense systems. This view is supported by clear signs of galaxy interactions that are seen in many groups. Spectroscopic observations reveal that typical relative velocities of galaxies in the groups are comparable to their internal stellar velocities. This should be conducive to strong gravitational interactions - more so than in rich clusters, where galaxy velocities are typically much higher. This suggests that compact groups could be excellent laboratories in which to study galaxy interactions and their effects. Compact groups often contain one or more galaxies whose redshift differs greatly from those of the other group members. If these galaxies are at the same distance as the other members, either entire galaxies are being ejected at high velocities from these groups, or some new physical phenomena must be occurring. If their redshifts are cosmological, we must explain why so many discordant galaxies are found in compact groups. In recent years much progress has been made in addressing these questions. Here, the author discusses the current observational data on compact groups and their implications

Assert Yourself! evaluating the performance of an HIV prevention intervention

Duration: November 1996 - June 2012 CHAPS is a collaborative programme of HIV health promotion for gay men and bisexual men living in England. It is co-ordinated by Terrence Higgins Trust on behalf of a range of project partners, including Sigma Research. The CHAPS programme includes a national HIV prevention mass media campaign each year, which usually include adverts, leaflets, magazines and other small media. Data from the Gay Men's Sex Survey is used to inform the targets and aims of these interventions and their development is supported by pre-testing with the target audience via focus groups. After the launch of the interventions, Sigma generates performance data about their performance. This includes annual coverage surveys where gay men and bisexual men are asked if they recognise the adverts, magazines and leaflets. This data is used to look in greater detail at the targeting of the campaigns. Using data from these surveys, we make recommendations on the most efficient media spend for advertising. In addition, we undertake end-user focus groups in which gay men and bisexual men are asked about their opinions, reactions and responses to the campaigns. This work follows on from the pre-testing groups, and looks at the relevance of the campaigns in situ. We also evaluate the sector development or facilitation interventions, undertaken within the CHAPS partnership including training events, Symposiums and the annual CHAPS conference. Three CHAPS summary final evaluation reports are available alongside many of the interim reports of CHAPS evaluation activities on which they are based. Click here for more details. CHAPS evaluation is funded by Terrence Higgins Trust as part of CHAPS, a national HIV prevention initiative funded by the Department of Health

Optical Tests of a 3.7-m diameter Liquid Mirror: Behavior under External Perturbations

We have built and tested a 3.7-m diameter liquid mirror that rotates on a ball bearing. We have carried out extensive optical tests. We find that although the ball bearing has a poor quality, the quality of the mirror, with mercury layers 1-mm thick, is surprisingly good. Taken at face values the instantaneous Strehl ratios indicate a mirror, that is not quite diffraction limited but usable for astronomical applications. However, the large coning error of the bearing (1.5 arcseconds P-V) induces an excessive wobble, considerably worsening the time averaged PSF. The most interesting result of the interferometry is that we do not see any evidence of the strong astigmatism that may have been expected from Coriolis forces.Comment: PDF format, 34 pages, 12 figures, (some figures reduced, full size figures in Applied Optics, Vol. 39, No 36, 5651

A Technique for Photometric Detection and Measurement of Unresolved Binary Systems

A technique is described for the detection and measurement of close binary systems whose images are unresolved. The method is based on analysis of the moment of inertia tensor of the image, from which the product of the binary flux ratio and square of the angular separation may be determined. Intrinsic asymmetries of the point-spread function are removed by comparison with the image of a reference star. Multiple exposures may be used to increase the signal-to-noise ratio without need of image alignment. An example is given of a simulated measurement of the dwarf carbon star system G77-61.Comment: PASP, in press. 17 pages including 2 figure

Eliminating the Coriols Effect in Liquid Mirrors

If uncorrected, the Coriolis force due to the rotation of the Earth causes significant aberration of images produced by large liquid-mirror telescopes. We show that this problem can be eliminated by a fixed compensating tilt of the liquid-mirror rotation axis. The required tilt angle, which is a function of latitude and mirror rotation rate, is of order 10 arcsec for current telescopes. This result removes the last fundamental obstacle to achieving diffraction-limited performance with large liquid mirrors.Comment: 8 pages 1 figure, submitted to PAS

History of wildland fires on Vandenberg Air Force Base, California

The fire history of the past 50 years for Vandenberg AFB, California was determined using aerial photography, field investigation, and historical and current written records. This constitutes a record of the vegetation age classes for the entire base. The location, cause, and fuel type for sixty fires from this time period were determined. The fires were mapped and entered into a geographic infomation system (GIS) for Vandenberg. Fire history maps derived from this GIS were printed at 1:9600 scale and are on deposit at the Vandenberg Environmental Task Force Office. Although some ecologically significant plant communities on Vandenberg are adapted to fire, no natural fire frequency could be determined, since only one fire possibly caused by lightning occurred in the area now within the base since 1937. Observations made during this study suggest that burning may encourage the invasion of exotic species into chaparral, in particular Burton Mesa or sandhill chaparral, an unusual and geographically limited form of chaparral found on the base