Constraining type Ia supernova models:SN 2011fe as A test case

The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia supernova (SN Ia) models, which may bring us closer to understanding the physical nature of these objects. Here, we explore how available and expected future observations of SN 2011fe can be used to constrain SN Ia explosion scenarios. We base our discussion on three-dimensional simulations of a delayed detonation in a Chandrasekhar-mass white dwarf and of a violent merger of two white dwarfs (WDs) - realizations of explosion models appropriate for two of the most widely discussed progenitor channels that may give rise to SNe Ia. Although both models have their shortcomings in reproducing details of the early and near-maximum spectra of SN 2011fe obtained by the Nearby Supernova Factory (SNfactory), the overall match with the observations is reasonable. The level of agreement is slightly better for the merger, in particular around maximum, but a clear preference for one model over the other is still not justified. Observations at late epochs, however, hold promise for discriminating the explosion scenarios in a straightforward way, as a nucleosynthesis effect leads to differences in the Co production. SN 2011fe is close enough to be followed sufficiently long to study this effect. © © 2012 The American Astronomical Society. All rights reserved.

Sub-luminous type Ia supernovae from the mergers of equal-mass white dwarfs with mass 0.9M

Type Ia supernovae are thought to result from thermonuclear explosions of carbong'oxygen white dwarf stars. Existing models generally explain the observed properties, with the exception of the sub-luminous 1991bg-like supernovae. It has long been suspected that the merger of two white dwarfs could give rise to a type Ia event, but hitherto simulations have failed to produce an explosion. Here we report a simulation of the merger of two equal-mass white dwarfs that leads to a sub-luminous explosion, although at the expense of requiring a single common-envelope phase, and component masses of 0.9M. The light curve is too broad, but the synthesized spectra, red colour and low expansion velocities are all close to what is observed for sub-luminous 1991bg-like events. Although the mass ratios can be slightly less than one and still produce a sub-luminous event, the masses have to be in the range 0.83M to 0.9M. © 2010 Macmillan Publishers Limited. All rights reserved.

US Credit Unions: Survival, Consolidation and Growth

This study uses hazard function estimations and time-series and cross-sectional growth regressions to examine the impact of exit through merger and acquisition (M&A) or failure, and internally-generated growth, on the firm-size distribution within the US credit union sector. Consolidation through M&A was the principal cause of a reduction in the number of credit unions, but impact on concentration was small. Divergence between the average internally-generated growth of smaller and larger credit unions was the principal driver of the rise in concentration.

The Polish Competition Authority Submits a Draft Amendment to the Polish Competition Act: Revolution or Fine-Tuning?

This piece highlights and offers a brief analysis of the most important of the
proposed changes to Polish competition law. The draft proposal envisages introduction of, inter alia, financial penalties for individuals, two-stage merger review process, important changes to the leniency program (including introduction of leniency plus), as well as such new tools as remedies and settlements.

Offshoring Clinical Trials: The Mutable Ethics, Weak Protections and Vulnerable Subjects of EU Law

In this paper I engage with science and technology studies work on pharmaceuticalisation to explore how European Union (EU) law helps to produce and support the preference for pharmaceutical responses in public health governance, while authorising the production of vulnerable subjects through the growing off-shoring of clinical trials. Drawing on the analysis of legal and policy documents, I demonstrate how EU law allows and legitimates the use of data procured from vulnerable subjects abroad for market authorisation and corporate profitability at home. This is possible because the EU has (de)selected international ethical frameworks in order to support the continued and growing use of clinical trials data from abroad. This has helped to stimulate the revision of international ethical frameworks in light of market needs, inscribing EU public health law within specific politics (that often remained obscured by the joint workings of legal and technological discourses). I suggest that law operates as part of a broader ‘technology’ – encompassing ethics and human rights discourses – that functions to optimise life through resort to market reasoning. Law is thereby reoriented, instrumentalised and deployed as part of a broader project aimed at (re)defining and limiting the boundaries of the EU's responsibility for public health, including the broader social production of public health problems and the unequal global order that the EU represents and helps to depoliticise and perpetuate. Overall, this limits the EU's responsibility and accountability for these failures, as well as another: the weak and mutable protections and insecure legacies for vulnerable trial subjects abroad.

The internal structure of asteroid (25143) Itokawa as revealed by detection of YORP spin-up *’**

Context. Near-Earth asteroid (25143) Itokawa was visited by the Hayabusa spacecraft in 2005, resulting in a highly detailed shape and surface topography model. This model has led to several predictions for the expected radiative torques on this asteroid, suggesting that its spin rate should be decelerating. Aims. To detect changes in rotation rate that may be due to YORP-induced radiative torques, which in turn may be used to investigate the interior structure of the asteroid. Methods. Through an observational survey spanning 2001 to 2013 we obtained rotational lightcurve data at various times over the last five close Earth-approaches of the asteroid. We applied a polyhedron-shape-modelling technique to assess the spin-state of the asteroid and its long term evolution. We also applied a detailed thermophysical analysis to the shape model determined from the Hayabusa spacecraft. Results. We have successfully measured an acceleration in Itokawa's spin rate of dω/dt = (3.54 ± 0.38) × 10 rad day, equivalent to a decrease of its rotation period of ~45 ms year. From the thermophysical analysis we find that the centre-of-mass for Itokawa must be shifted by ~21 m along the long-axis of the asteroid to reconcile the observed YORP strength with theory. Conclusions. This can be explained if Itokawa is composed of two separate bodies with very different bulk densities of 1750 ± 110 kg m and 2850 ± 500 kg m, and was formed from the merger of two separate bodies, either in the aftermath of a catastrophic disruption of a larger differentiated body, or from the collapse of a binary system. We therefore demonstrate that an observational measurement of radiative torques, when combined with a detailed shape model, can provide insight into the interior structure of an asteroid. Futhermore, this is the first measurement of density inhomogeneity within an asteroidal body, that reveals significant internal structure variation. A specialised spacecraft is normally required for this.

'Super-Chandrasekhar' Type Ia Supernovae at nebular epochs

We present a first systematic comparison of superluminous Type Ia supernovae (SNe Ia) at late epochs, including previously unpublished photometric and spectroscopic observations of SN 2007if, SN 2009dc and SNF20080723-012. Photometrically, the objects of our sample show a diverse late-time behaviour, some of them fading quite rapidly after a light-curve break at ∼ 150-200 d. The latter is likely the result of flux redistribution into the infrared, possibly caused by dust formation, rather than a true bolometric effect. Nebular spectra of superluminous SNe Ia are characterized by weak or absent [Fe III] emission, pointing at a low ejecta ionization state as a result of high densities. To constrain the ejecta and Ni masses of superluminous SNe Ia, we compare the observed bolometric light curve of SN 2009dc with synthetic model light curves, focusing on the radioactive tail after ∼60 d. Models with enough Ni to explain the light-curve peak by radioactive decay, and at the same time sufficient mass to keep the ejecta velocities low, fail to reproduce the observed light-curve tail of SN 2009dc because of too much γ -ray trapping.We instead propose a model with ∼1M of Ni and ∼2 M of ejecta, which may be interpreted as the explosion of a Chandrasekhar-mass white dwarf (WD) enshrouded by 0.6-0.7 M of C/O-rich material, as it could result from a merger of two massive C/O WDs. This model reproduces the late light curve of SN 2009dc well. A flux deficit at peak may be compensated by light from the interaction of the ejecta with the surrounding material.

Political Posturing or Real Powers: Control of Genetically Modified Crops by the Member States and their Regions

The cultivation of genetically modified (GM) crops in the EU is highly harmonised, involving a central authorisation procedure that aims to ensure a high level of environmental and human health protection. However conflicts over authority persist and the Commission has responded to a combination of internal and external pressures with a more flexible approach to coexistence, a proposed opt-out clause and recently a promise by the head of the Commission to review the existing EU GM legislative regime, providing an opportunity to consider and suggest paths of development. In light of the significance of multilevel governance and subsidiarity for GM cultivation, this paper considers the policy-making powers of the Member States and subnational regions in this regime, focussing upon post-authorisation options in particular. A number of core mechanisms exist, including voluntary measures, safeguard clauses, coexistence measures, a proposed express opt-out and Article 4(2) TEU on ‘national identity. These mechanisms are examined in light of the goals and challenges of multilevel governance, in order to consider whether the relevant powers are located at the appropriate level. Overall, it is apparent that the developments occurring at the EU level are strengthening multilevel governance, but with significant opportunities to improve it further through focussing on the supporting roles and the regional levels in particular.

Direct Detection of YORP Spin-up on Asteroid (25143) Itokawa and Implications for its Internal Structure

Near-Earth asteroid (25143) Itokawa was visited by the Hayabusa spacecraft in 2005, resulting in a highly detailed surface shape and topography model. This model has led to several predictions for the expected radiative torques on this asteroid, suggesting that its spin rate should be decelerating. Through an observational survey spanning 2001 to 2013 we have successfully measured an acceleration in its spin rate of dω/dt = 3.54 (± 0.38) × 10^(-8) rad day^(-2), equivalent to a decrease of its rotation period of ~ 45 ms year^(-1). Using the shape model determined from the Hayabusa spacecraft, we applied a detailed thermophysical analysis, to reconcile the predicted YORP strength with that observed. We find that the center-of-mass for Itokawa must be shifted by ~20 m along the long-axis of the asteroid to reconcile observations with theory. This can be explained if Itokawa is composed of two separate bodies with very different bulk densities of 1740 ± 110 kg m^(-3) and 2730 ± 440 kg m^(-3), and was formed from the merger of two separate bodies, consistent with the collapse of a binary system or the re-accumulation of material from a catastrophic collisional disruption. We demonstrate that an observational measurement of radiative torques, when combined with a detailed shape model, can provide insight into the interior structure of an asteroid.

The Changing Context for Planning Education in the UK and the Prospects for Research-Led, Practice-Engaged Teaching

The UK’s Royal Town Planning Institute (RTPI) celebrates its centenary in 2014, marking 100 years of close relationships between university-based Planning Schools and a professional body focussed on planning practice. During this period, the context for university education and the very idea of planning has changed dramatically contributing to a continual renegotiation of the relationships between the planning profession and the educational institutions it accredits. These changes have been particularly acute in the last ten years where a number of factors have forced a rapid change in the nature of planning education in the UK. This has included a boom and then slump in the number of planning students linked to the national economic situation, a reorganisation of many planning schools and their merger with cognate disciplines such as geography and an increased focus of research output, rather than professional engagement the key institutional indicator of success. This last factor adds a particularly new dimension to the profession-university relationship, which could potentially lead to either a straining of tensions or a synergy through research-led teaching that could significantly benefit both.

This paper will briefly review the evolution of UK planning schools and the co-evolution of the main ideas informing planning education. It will then describe the current profile of UK planning schools, based on an extensive national survey conducted on behalf of the Royal Town Planning Institute. The paper will then critically review the main challenges and opportunities facing UK Planning Schools in the context of changes in both planning practice and higher education. It will then move on to the concept of research-led teaching, drawing on current practice in the UK and review how well this concept serves students and the idea of developing reflective planning practitioners. Finally, the paper will seek to draw broad lessons from the experience of the UK and reflect on the type of planning education that can best serve planning professions in a variety of international contexts in the future.

Defining the role of common variation in the genomic and biological architecture of adult human height

Using genome-wide data from 253,288 individuals, we identified 697 variants at genome-wide significance that together explained one-fifth of the heritability for adult height. By testing different numbers of variants in independent studies, we show that the most strongly associated 1/42,000, 1/43,700 and 1/49,500 SNPs explained 1/421%, 1/424% and 1/429% of phenotypic variance. Furthermore, all common variants together captured 60% of heritability. The 697 variants clustered in 423 loci were enriched for genes, pathways and tissue types known to be involved in growth and together implicated genes and pathways not highlighted in earlier efforts, such as signaling by fibroblast growth factors, WNT/I 2-catenin and chondroitin sulfate-related genes. We identified several genes and pathways not previously connected with human skeletal growth, including mTOR, osteoglycin and binding of hyaluronic acid. Our results indicate a genetic architecture for human height that is characterized by a very large but finite number (thousands) of causal variants.

New genetic loci link adipose and insulin biology to body fat distribution

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.

Genetic studies of body mass index yield new insights for obesity biology

Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10(-8)), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ∼2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.

Regulating Genetically Modified Organisms in Ireland – Laissez faire approach?

This chapter examines the legal framework applicable to genetically modified organisms (GMOs) in Ireland, bearing in mind the limited presence of GMOs. As a member of the European Union (EU), a specific, process-based regime applies regarding the authorisation and regulation of GMOs. This is intended to ensure a high level of environmental and human health protection and also enable producer and consumer choice. This regime is highly harmonized, but allows some flexibility regarding its implementation and, soon, the potential to opt-out from cultivation in part or entirely. Although, Ireland has only legislated on the area to the extent and in the manner required by the EU, it may avail of the opt-out in future – understandable in light of the lack of any cultivation currently and the green image of Ireland.
Complementary horizontal legislation and common law principles, relevant to labelling and varying forms of liability, deal with most issues that might arise quite comprehensively. However, they are quite complicated, overlapping and untailored and it is worth considering whether specific legislation should be developed to deal with liability related to GMOs.
Overall, Ireland holds varying stances to different forms of GMOs, with the greatest acceptance and use of GM-feed for pragmatic reasons. It has not developed a specific Irish approach, copy-pasting EU legislation and relying upon existing law to deal with any issues. This is understandable in light of the high level of harmonization and limited presence of GMOs in Ireland, but nonetheless will need to be developed as the availability of GMOs increases.

Attaining Subsidiarity-Based Multilevel Governance of Genetically Modified Cultivation?

The cultivation of genetically modified (GM) crops in the EU is highly harmonised, but with persisting conflicts over authority. The Commission responded to internal and external pressures with a more flexible approach to coexistence, a proposed opt-out clause and a promise to review the existing EU GM regime, providing an opportunity to consider and suggest paths of development. This article considers the post-authorisation policy-making powers of Member States and subnational regions, in light of subsidiarity-based multilevel governance. It considers the different approaches to risk-centred issues and more general policy choices. Overall, the developments occurring at the EU level are strengthening subsidiarity-based multilevel governance within the GM cultivation regime, but with significant opportunities to improve it further through focussing on the complementary powers, coordination and the regional levels in particular.