Hard lessons for lifelong learners? age and experience in the graduate labour market

The expansion of the higher education system and widening access to undergraduate study has led to growing diversity within the graduate labour supply, including increasing numbers who studied for their degrees as mature students. Analysis of graduates entering the labour market prior to the major expansion in the early 1990s indicated that those over the age of 30 had considerably more difficulty than younger graduates in accessing the career opportunities for which their education had equipped them. Is this still the case for more recent graduates? Drawing on a major qualitative and quantitative study of a class of graduates who completed their undergraduate degree courses in 1995, this paper explores early career development and employment outcomes according to age at graduation. Although we find considerable diversity among all age groups, mature graduates were more likely than their younger peers to experience difficulty in accessing appropriate employment, had a lower rate of earnings growth and expressed higher levels of dissatisfaction with their jobs. © 2007 Blackwell Publishing Ltd

Simulation Tools for Detector and Instrument Design

The high performance requirements at the European Spallation Source have been driving the technological advances on the neutron detector front. Now more than ever is it important to optimize the design of detectors and instruments, to fully exploit the ESS source brilliance. Most of the simulation tools the neutron scattering community has at their disposal target the instrument optimization until the sample position, with little focus on detectors. The ESS Detector Group has extended the capabilities of existing detector simulation tools to bridge this gap. An extensive software framework has been developed, enabling efficient and collaborative developments of required simulations and analyses -- based on the use of the Geant4 Monte Carlo toolkit, but with extended physics capabilities where relevant (like for Bragg diffraction of thermal neutrons in crystals). Furthermore, the MCPL (Monte Carlo Particle Lists) particle data exchange file format, currently supported for the primary Monte Carlo tools of the community (McStas, Geant4 and MCNP), facilitates the integration of detector simulations with existing simulations of instruments using these software packages. These means offer a powerful set of tools to tailor the detector and instrument design to the instrument application

Ligand-based virtual screening using binary kernel discrimination

This paper discusses the use of a machine-learning technique called binary kernel discrimination (BKD) for virtual screening in drug- and pesticide-discovery programmes. BKD is compared with several other ligand-based tools for virtual screening in databases of 2D structures represented by fragment bit-strings, and is shown to provide an effective, and reasonably efficient, way of prioritising compounds for biological screening

Frontiers in Coalescent Theory: Pedigrees, Identity-by-Descent, and Sequentially Markov Coalescent Models

The coalescent is a stochastic process that describes the genetic ancestry ofindividuals sampled from a population. It is one of the main tools of theoretical population genetics and has been used as the basis of many sophisticated methods of inferring the demographic history of a population from a genetic sample. This dissertation is presented in four chapters, each developing coalescent theory to some degree. In the first chapter, I investigate how patterns of coalescence are affected by the population pedigree in structured populations, showing that the pedigree has longer-term effects in structured populations than in unstructured populations. Based on my findings, I develop a conceptual framework for jointly inferring population sizes, migration rates, and the recent pedigree of sampled individuals, and I demonstrate the efficacy of this approach in an application to simulated data. In Chapter 2, I present a theoretical study of the distribution of segments of identity-by-descent, showing how the accuracy of predictions made based on sequentially Markov coalescent models depends on the particular model being used as the basis of calculations. In the third chapter, I undertake a theoretical comparison of two approximations, termed the SMC and SMC', to the full model of coalescence with recombination. I derive new theoretical properties of the SMC' and use these properties to demonstrate that the SMC' is, in a well-defined sense, the most appropriate first-order approximation to the full coalescent with recombination. I also show that estimates of population size based on the SMC are statistically inconsistent. Finally, in Chapter 4, I develop a coalescent hidden Markov model approach to inferring the demographic and reproductive history of a triploid asexual lineage derived from a diploid sexual ancestor. The motivation for this project is an ongoing collaborative effort to sequence and analyze the genomes of sexual and asexual lineages of the New Zealand snail Potamopyrgus antipodarum. The method I present in this chapter will be applied to these genomes to infer when triploid asexual lineages were derived from sexual ancestors and to describe the demographic history of those sexual ancestors. Here, I investigate the this method with simulated asexual genomes.Biology, Organismic and Evolutionar

Bottleneck and selection in the germline and maternal age influence transmission of mitochondrial DNA in human pedigrees.

Heteroplasmy-the presence of multiple mitochondrial DNA (mtDNA) haplotypes in an individual-can lead to numerous mitochondrial diseases. The presentation of such diseases depends on the frequency of the heteroplasmic variant in tissues, which, in turn, depends on the dynamics of mtDNA transmissions during germline and somatic development. Thus, understanding and predicting these dynamics between generations and within individuals is medically relevant. Here, we study patterns of heteroplasmy in 2 tissues from each of 345 humans in 96 multigenerational families, each with, at least, 2 siblings (a total of 249 mother-child transmissions). This experimental design has allowed us to estimate the timing of mtDNA mutations, drift, and selection with unprecedented precision. Our results are remarkably concordant between 2 complementary population-genetic approaches. We find evidence for a severe germline bottleneck (7-10 mtDNA segregating units) that occurs independently in different oocyte lineages from the same mother, while somatic bottlenecks are less severe. We demonstrate that divergence between mother and offspring increases with the mother's age at childbirth, likely due to continued drift of heteroplasmy frequencies in oocytes under meiotic arrest. We show that this period is also accompanied by mutation accumulation leading to more de novo mutations in children born to older mothers. We show that heteroplasmic variants at intermediate frequencies can segregate for many generations in the human population, despite the strong germline bottleneck. We show that selection acts during germline development to keep the frequency of putatively deleterious variants from rising. Our findings have important applications for clinical genetics and genetic counseling

Controls on the transport of oceanic heat to Kangerdlugssuaq Glacier, East Greenland

Greenland's marine-terminating glaciers may be sensitive to oceanic heat, but the fjord processes controlling delivery of this heat to glacier termini remain poorly constrained. Here we use a three-dimensional numerical model of Kangerdlugssuaq Fjord, East Greenland, to examine controls on fjord/shelf exchange. We find that shelf-forced intermediary circulation can replace up to ~25% of the fjord volume with shelf waters within 10 d, while buoyancy-driven circulation (forced by subglacial runoff from marine-terminating glaciers) exchanges ~10% of the fjord volume over a 10 d period under typical summer conditions. However, while the intermediary circulation generates higher exchange rates between the fjord and shelf, the buoyancy-driven circulation is consistent over time hence more efficient at transporting water along the full length of the fjord. We thus find that buoyancy-driven circulation is the primary conveyor of oceanic heat to glaciers during the melt season. Intermediary circulation will however dominate during winter unless there is sufficient input of fresh water from subglacial melting. Our findings suggest that increasing shelf water temperatures and stronger buoyancy-driven circulation caused the heat available for melting at Kangerdlugssuaq Glacier to increase by ~50% between 1993–2001 and 2002–11, broadly coincident with the onset of rapid retreat at this glacier

Narrow genetic basis for the Australian dingo confirmed through analysis of paternal ancestry

The dingo (Canis lupus dingo) is an iconic animal in the native culture of Australia, but archaeological and molecular records indicate a relatively recent history on the continent. Studies of mitochondrial DNA (mtDNA) imply that the current dingo population was founded by a small population of already tamed dogs from Southeast Asia. However, the maternal genetic data might give a unilateral picture, and the gene pool has yet to be screened for paternal ancestry. We sequenced 14,437 bp of the Y-chromosome (Y-chr) from two dingoes and one New Guinea Singing Dog (NGSD). This positioned dingo and NGSD within the domestic dog Y-chr phylogeny, and produced one haplotype not detected before. With this data, we characterized 47 male dingoes in 30 Y-chr single-nucleotide polymorphism sites using protease-mediated allele-specific extension technology. Only two haplotypes, H3 and H60, were found among the dingoes, at frequencies of 68.1 and 31.9 %, respectively, compared to 27 haplotypes previously established in the domestic dog. While H3 is common among Southeast Asian dogs, H60 was specifically found in dingoes and the NGSD, but was related to Southeast Asian dog Y-chr haplotypes. H3 and H60 were observed exclusively in the western and eastern parts of Australia, respectively, but had a common range in Southeast. Thus, the Y-chr diversity was very low, similar to previous observations for d-loop mtDNA. Overall genetic evidence suggests a very restricted introduction of the first dingoes into Australia, possibly from New Guinea. This study further confirms the dingo as an isolated feral dog. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10709-012-9658-5) contains supplementary material, which is available to authorized users

NEW AND SIGNIFICANT ISLAND RECORDS, RANGE EXTENSIONS AND ELEVATIONAL EXTENSIONS OF BIRDS IN EASTERN SULAWESI, ITS NEARBY SATELLITES, AND TERNATE

The Wallacean Region continues to be widely unexplored even in such relatively well-known animal groups as birds (Aves). We report on the results of an ornithological expedition from late Nov 2013 through early Jan 2014 to eastern Sulawesi and a number of satellite islands (Togian, Peleng, Taliabu) as well as Ternate. The expedition targeted and succeeded with the collection of 7–10 bird taxa previously documented by us and other researchers but still undescribed to science. In this contribution, we provide details on numerous first records of bird species outside their previously known geographic or elevational ranges observed or otherwise recorded during this expedition. We also document what appears to be a genuinely new taxon, possibly at the species level of kingfisher from Sulawesi that has been overlooked by previous ornithologists. Our results underscore our fragmentary knowledge of the composition of the avifauna of eastern Indonesia, and demonstrate that there continues to be a high degree of cryptic, undescribed avian diversity on these islands more than a century and a half after they were visited by Alfred Russel Wallace and other collectors