Microbial metabolism: optimal control of uptake versus synthesis

Microbes require several complex organic molecules for growth. A species may obtain a required factor by taking up molecules released by other species or by synthesizing the molecule. The patterns of uptake and synthesis set a flow of resources through the multiple species that create a microbial community. This article analyzes a simple mathematical model of the tradeoff between uptake and synthesis. Key factors include the influx rate from external sources relative to the outflux rate, the rate of internal decay within cells, and the cost of synthesis. Aspects of demography also matter, such as cellular birth and death rates, the expected time course of a local resource flow, and the associated lifespan of the local population. Spatial patterns of genetic variability and differentiation between populations may also strongly influence the evolution of metabolic regulatory controls of individual species and thus the structuring of microbial communities. The widespread use of optimality approaches in recent work on microbial metabolism has ignored demography and genetic structure

Teacher numbers (SPICe Briefing; 11/08)

"This briefing summarises trends in teacher numbers, probationer employment and related policy regarding intake targets for student teachers." - Cover

Cosmic Gamma-Ray Background from Star-Forming Galaxies

The origin of the extragalactic gamma-ray background is a pressing cosmological mystery. The Fermi Gamma-Ray Space Telescope has recently measured the intensity and spectrum of this background; both are substantially different from previous measurements. We present a novel calculation of the gamma-ray background from normal star-forming galaxies. Contrary to long-standing expectations, we find that numerous but individually faint normal galaxies may comprise the bulk of the Fermi signal, rather than rare but intrinsically bright active galaxies. This result has wide-ranging implications, including: the possibility to probe the cosmic star formation history with gamma rays; the ability to infer the cosmological evolution of cosmic rays and galactic magnetic fields; and an increased likelihood of identifying subdominant components from rare sources (e.g., dark matter clumps) through their large anisotropy.Comment: 5 pages, 1 figure. Matches version published in ApJL. Sharper focus on normal (vs starburst) galaxies. Basic conclusions unchange

Research needs for an improved primary care response to chronic non-communicable diseases in Africa.

With non-communicable diseases (NCDs) projected to become leading causes of morbidity and mortality in developing countries, research is needed to improve the primary care response, especially in sub-Saharan Africa. This region has a particularly high double burden of communicable diseases and NCDs and the least resources for an effective response. There is a lack of good quality epidemiological data from diverse settings on chronic NCD burden in sub-Saharan Africa, and the approach to primary care of people with chronic NCDs is currently often unstructured. The main primary care research needs are therefore firstly, epidemiological research to document the burden of chronic NCDs, and secondly, health system research to deliver the structured, programmatic, public health approach that has been proposed for the primary care of people with chronic NCDs. Documentation of the burden and trends of chronic NCDs and associated risk factors in different settings and different population groups is needed to enable health system planning for an improved primary care response. Key research issues in implementing the programmatic framework for an improved primary care response are how to (i) integrate screening and prevention within health delivery; (ii) validate the use of standard diagnostic protocols for NCD case-finding among patients presenting to the local health facilities; (iii) improve the procurement and provision of standardised treatment and (iv) develop and implement a data collection system for standardised monitoring and evaluation of patient outcomes. Important research considerations include the following: selection of research sites and the particular NCDs targeted; research methodology; local research capacity; research collaborations; ethical issues; translating research findings into policy and practice and funding. Meeting the research needs for an improved health system response is crucial to deliver effective, affordable and equitable care for the millions of people with chronic NCDs in developing countries in Africa

Nonthermal Emission from Star-Forming Galaxies

The detections of high-energy gamma-ray emission from the nearby starburst galaxies M82 & NGC253, and other local group galaxies, broaden our knowledge of star-driven nonthermal processes and phenomena in non-AGN star-forming galaxies. We review basic aspects of the related processes and their modeling in starburst galaxies. Since these processes involve both energetic electrons and protons accelerated by SN shocks, their respective radiative yields can be used to explore the SN-particle-radiation connection. Specifically, the relation between SN activity, energetic particles, and their radiative yields, is assessed through respective measures of the particle energy density in several star-forming galaxies. The deduced energy densities range from O(0.1) eV/cm^3 in very quiet environments to O(100) eV/cm^3 in regions with very high star-formation rates.Comment: 17 pages, 5 figures, to be published in Astrophysics and Space Science Proceeding

The Mass and Radius of the Neutron Star in the Bulge Low-Mass X-ray Binary KS 1731-260

Measurements of neutron star masses and radii are instrumental for determining the equation of state of their interiors, understanding the dividing line between neutron stars and black holes, and for obtaining accurate statistics of source populations in the Galaxy. We report here on the measurement of the mass and radius of the neutron star in the low-mass X-ray binary KS 1731-260. The analysis of the spectroscopic data on multiple thermonuclear bursts yields well-constrained values for the apparent angular area and the Eddington flux of the source, both of which depend in a distinct way on the mass and radius of the neutron star. The binary KS 1731-260 is in the direction of the Galactic bulge, allowing a distance estimate based on the density of stars in that direction. Making use of the Han & Gould model, we determine the probability distribution over the distance to the source, which is peaked at 8 kpc. Combining these measurements, we place a strong upper bound on the radius of the neutron star, R <= 12 km, while confining its mass to M <= 1.8 M_sun.Comment: submitted to Ap

Convictions for summary insolvency offences committed by company directors

The Australian Securities and Investments Commission (ASIC) investigates and prosecutes certain strict liability criminal offences by directors before local and Magistrates’ courts across Australia. Until December 2011, ASIC made public the details of each successful case by periodically releasing conviction reports on its website and through media releases. In this paper, an analysis of the raw information in ASIC conviction reports for the five calendar years 2006 to 2010 is presented to provide statistical data on convictions and fines obtained by ASIC under its court-based enforcement activities, with an emphasis on insolvency offences. The analysis reveals that under its summary prosecution program, ASIC’s focus turned almost exclusively to insolvency crimes committed by directors of collapsed, insolvent companies, where they have failed to assist liquidators. The analysis reveals a trend toward fewer convictions (except in New South Wales) and smaller fines for these ‘fail-to-assist’ offences between 2006 and 2010. This paper also provides background information about the traditional role played by insolvency practitioners in detecting corporate crime and assisting with prosecution, as well as the character and significance of summary insolvency offences. It suggests that prosecution of these summary insolvency offences may be important to the integrity of Australia’s regime of corporate insolvency law. By arrangement with the Commonwealth Director of Public Prosecutions, ASIC is permitted to conduct its own prosecutions of what the Commonwealth Director of Public Prosecutions describes as minor regulatory offences against the Corporations Act 2001 (Cth) (the Act). Under this arrangement, ASIC commenced an expanded summary prosecutions program in 2002 and as part of this, received special funding for a Liquidator Assistance Program. ASIC’s first report on the outcomes of these initiatives showed that most of the convictions achieved between 2002 and 2005 were in respect of offences relating to failure by company officers to assist insolvency practitioners (ASIC 2005). Analysis of similar ASIC reports since 2005 reveals that convictions for such insolvency offences now predominate. Further, analysis of these reports shows a reduction in the average fine being imposed by the courts, a fall in the actual number of defendants convicted and offence rates varying between jurisdictions. The purpose of this scoping study is to analyse and document changes in the number of convictions achieved by ASIC for failure to assist-type insolvency offences identified during the liquidation process, to examine changes in the penalties awarded by the courts for such offences, to illuminate enforcement and prosecution action being taken in an area of white collar crime that is rarely discussed outside the insolvency industry and to point to the nature of the issues that should be examined through additional research

School buildings: frequently asked questions (SPICe briefing; 11/11)

"This briefing gives an overview of key facts relating to school buildings, based on enquiries frequently received in SPICe. This updates SPICe briefing 09/72." - Cover