Very-long-baseline radio interferometry surveys of the compact structure in active galactic nuclei

Very-long-baseline radio interferometry (VLBI) imaging surveys have been undertaken since the late 1970s. The sample sizes were initially limited to a few tens of objects but the snapshot technique has now allowed samples containing almost 200 sources to be studied. The overwhelming majority of powerful compact sources are asymmetric corejects of one form or another, most of which exhibit apparent superluminal motion. However 5-10% of powerful flat-spectrum sources are 100-parsec (pc)-scale compact symmetric objects; these appear to form a continuum with the 1-kpc-scale double-lobed compact steep-spectrum sources, which make up 15-20% of lower frequency samples. It is likely that these sub-galactic-size symmetric sources are the precursors to the large-scale classical double sources. There is a surprising peak around 90 degrees in the histogram of misalignments between the dominant source axes on parsec and kiloparsec scales; this seems to be associated with sources exhibiting a high degree of relativistic beaming. VLBI snapshot surveys have great cosmological potential via measurements of both proper motion and angular size vs. redshift as well as searches for gravitational "millilensing."     

Critical success in management development

Details the results of an attempt to identify the impact of a comprehensive management development programme on organizational effectiveness within the health service public sector. Concludes that management development programmes must have a prespecified set of strategically linked outcomes, identifying the benefits to the organization, and a set of critical success factor measures to determine their achievement or otherwise. Programmes which do not result in managers feeling empowered will be criticized in not impacting positively on the organization.     

Economics 101: exploring the land of costs

The word "cost" is a slippery, chameleon-like beast that changes its meaning to suit the occasion. The author's "economish" dictionary will help you survive the purchasing jungle.     

Establishing a new university department of rural health: the first 2 years of the South Australian Centre for Rural and Remote Health

ABSTRACT: This study aimed to describe the establishment of a new University Department of Rural Health (UDRH) in South Australia and to report early achievements. In May 1997, the UDRH was established, key staff were recruited, infrastructure was developed and in April 1998 a Joint University Committee on Rural and Remote Health was formed. By mid-1999, 14 full-time equivalent staff were employed in Whyalla and Adelaide. Early achievements include: review of undergraduate rural placements; increased rural clinical placements by 1000 student-weeks; partnership with the Dental School resulting in training opportunities and falling public dental waiting lists; multidisciplinary teaching practices in four rural sites; priority public health projects established; competitive research grants won; and a capital grant to strengthen Aboriginal health services infrastructure secured. These early achievements demonstrate UDRH potential to have a real impact on health worker education, service delivery, and public health status in rural and remote areas. This strong foundation must now be built on.     

Serum thyroxine binding capacity-dependent bias in an automated free thyroxine assay

The magnitude of serum thyroxine (T4) binding capacity (sBC) dependent bias in the AXSYM free thyroxine (FT4) assay was assessed using two recently described tests. One of the tests uses a direct equilibrium dialysis (ED) FT4 assay as the reference method. The results obtained with the AXSYM method were compared with those obtained by the ED FT4 method in patient sera having a wide range of sBC. The other test involves comparison of the FT4 results obtained following dilution of sera by an inert buffer, to theoretically derived FT4 results. As serum dilution causes a predictable decrease in sBC, the demonstration of a negative bias whose magnitude increases in parallel to the dilution, is indicative of an sBC-dependent bias. The AXSYM FT4 assay exhibited a significant sBC-dependent bias. This sBC-dependent bias is likely to have been caused by the presence of significant amounts of T4 binding proteins in the assay reagents.     

Crime: social disorganization and relative deprivation

Crime is seldom considered as an outcome in public health research. Yet major theoretical and empirical developments in the field of criminology during the past 50 years suggest that the same social environmental factors which predict geographic variation in crime rates may also be relevant for explaining community variations in health and wellbeing. Understanding the causes of variability in crime across countries and across regions within a country will help us to solve one of the enduring puzzles in public health, viz. why some communities are healthier than others. The purpose of this paper is to present a conceptual framework for investigating the influence of the social context on community health, using crime as the indicator of collective wellbeing. We argue that two sets of societal characteristics influence the level of crime: the degree of relative deprivation in society (for instance, measured by the extent of income inequality), and the degree of cohesiveness in social relations among citizens (measured, for instance, by indicators of 'social capital' and 'collective efficacy'). We provided a test of our conceptual framework using state-level ecologic data on violent crimes and property crimes within the USA. Violent crimes (homicide, assault, robbery) were consistently associated with relative deprivation (income inequality) and indicators of low social capital. Among property crimes, burglary was also associated with deprivation and low social capital. Areas with high crime rates tend also to exhibit higher mortality rates from all causes, suggesting that crime and population health share the same social origins. Crime is thus a mirror of the quality of the social environment.     

Low-calcium-induced enhancement of chemical synaptic transmission from photoreceptors to horizontal cells in the vertebrate retina.

According to the classical calcium hypothesis of synaptic transmission, the release of neurotransmitter from presynaptic terminals occurs through an exocytotic process triggered by depolarization-induced presynaptic calcium influx. However, evidence has been accumulating in the last two decades indicating that, in many preparations, synaptic transmitter release can persist or even increase when calcium is omitted from the perfusing saline, leading to the notion of a "calcium-independent release" mechanism. Our study shows that the enhancement of synaptic transmission between photoreceptors and horizontal cells of the vertebrate retina induced by low-calcium media is caused by an increase of calcium influx into presynaptic terminals. This paradoxical effect is accounted for by modifications of surface potential on the photoreceptor membrane. Since lowering extracellular calcium concentration may likewise enhance calcium influx into other nerve cells, other experimental observations of "calcium-independent" release may be reaccommodated within the framework of the classical calcium hypothesis without invoking unconventional processes.