Moduli and periods of simply connected Enriques surfaces

We describe a period map for those simply connected Enriques surfaces in characteristic 2 whose canonical double cover is K3. The moduli stack for these surfaces has a Deligne-Mumford quotient that is an open substack of a $\mathbb P^1$-bundle over the period space. We also give some general results relating local and global moduli for algebraic varieties and describe the difference in their dimensions in terms of the failure of the automorphism group scheme to be reduced

Stability of highly cooled hypervelocity boundary layers

The influence of high levels of wall cooling on the stability of hypervelocity boundary layers is investigated. Such conditions are relevant to experiments in high-enthalpy impulse facilities, where the wall temperature is much smaller than the free-stream temperature, as well as to some real flight scenarios. Some effects of wall cooling are well known, for instance, the stabilization of the first mode and destabilization of the second mode. In this paper, several new instability phenomena are investigated that arise only for high Mach numbers and high levels of wall cooling. In particular, certain unstable modes can travel supersonically with respect to the free stream, which changes the nature of the dispersion curve and leads to instability over a much wider band of frequencies. The cause of this phenomenon, the range of parameters for which it occurs and its implications for boundary layer stability are examined. Additionally, growth rates are systematically reported for a wide range of conditions relevant to high-enthalpy impulse facilities, and the stability trends in terms of Mach number and wall temperature are mapped out. Thermal non-equilibrium is included in the analysis and its influence on the stability characteristics of flows in impulse facilities is assessed

Evidence for ion acceleration by oscillations in the discharge plasma of ion engines

The hollow cathode discharge plasma in ion engines is highly non-uniform, geometrically complex, and confined by a magnetic field; elucidating the mechanisms responsible for producing ions with anomalously high energies observed in the downstream regions of hollow cathodes will contribute to understanding the behavior of complex plasmas. Ions with energies in excess of ten times greater than the energy associated with electrostatic acceleration from the largest steady-state potential difference in the plasma discharge of ion engines have been detected

Differential Interferometric Measurement of Instability in a Hypervelocity Boundary Layer

The prediction of laminar–turbulent transition location in high-speed boundary layers is critical to hypersonic vehicle design because of the weight implications of increased skin friction and surface heating rate after transition. Current work in T5 (the California Institute of Technology’s free piston reflected shock tunnel) includes the study of problems relevant to hypervelocity boundary layer transition on cold-wall slender bodies. With the ability to ground-test hypervelocity flows, the study of energy exchange between the boundary layer instability and the internal energy of the fluid is emphasized. The most unstable mode on a cold-wall slender body at zero angle of incidence is not the viscous instability (as in low-speed boundary layers) but the acoustic instability. Quantitative characterization of this disturbance is paramount to the development of transition location-prediction tools

The molecular genetic analysis of the expanding pachyonychia congenita case collection

BACKGROUND: Pachyonychia congenita (PC) is a rare autosomal dominant keratinizing disorder characterized by severe, painful, palmoplantar keratoderma and nail dystrophy, often accompanied by oral leucokeratosis, cysts and follicular keratosis. It is caused by mutations in one of five keratin genes: KRT6A, KRT6B, KRT6C, KRT16 or KRT17. OBJECTIVES: To identify mutations in 84 new families with a clinical diagnosis of PC, recruited by the International Pachyonychia Congenita Research Registry during the last few years. METHODS: Genomic DNA isolated from saliva or peripheral blood leucocytes was amplified using primers specific for the PC-associated keratin genes and polymerase chain reaction products were directly sequenced. RESULTS: Mutations were identified in 84 families in the PC-associated keratin genes, comprising 46 distinct keratin mutations. Fourteen were previously unreported mutations, bringing the total number of different keratin mutations associated with PC to 105. CONCLUSIONS: By identifying mutations in KRT6A, KRT6B, KRT6C, KRT16 or KRT17, this study has confirmed, at the molecular level, the clinical diagnosis of PC in these families

Commissioning through Competition and Cooperation. Interim Report

Policy background A wide ranging set of reforms is being introduced into the English NHS. The reforms are designed to increase the market-like behaviour of providers of care with a view to improving efficiency, quality and responsiveness of services (DH, 2005; Health and Social Care Act, 2012; ‘HSCA 2012’) and they span the New Labour government and current Coalition government regimes. The idea behind these reforms is that competition between a wider range of providers will produce the desired results such as improved quality and greater efficiency. At the same time, it is still necessary for providers of care to cooperate with each other in order to deliver high quality care. There are many aspects of care quality where cooperation is needed, such as continuity of care as patients move between organisations, and sharing of knowledge between clinicians. Documents such as the Principles and rules for cooperation and competition (DH, 2010) (and more recently, HSCA 2012) explained how the NHS was required to deal with competition and cooperation simultaneously. The principles included the requirement for ‘providers and commissioners to cooperate to deliver seamless and sustainable care to patients’ (principle 4), while also prohibiting commissioners and providers from reaching ‘agreements which restrict commissioner or patient choice against patients’ or taxpayers’ interests’ (principle 6). Similar principles are enshrined in the HSCA 2012, as supplemented by guidance issued by Monitor. Moreover, a Statutory Instrument was issued under the HSCA 2012 which set out the rules governing procurement of health services by NHS commissioners , indicating that competitive procurement is to be preferred (The National Health Service Procurement Patient Choice and Competition No 2 Regulations 2013). A national panel was established to interpret the principles (the Cooperation and Competition Panel, CCP) and advise the NHS on what behaviours were acceptable. Under the HSCA 2012, Monitor (as the new economic regulator) took over some of the functions of the CCP and along with the national competition authorities (being, since April 2014 the Competition and Markets Authority, and prior to that, The Office of Fair Trading, OFT, and the Competition Commission (CC) has powers to enforce competition law to prevent anti-competitive behaviour. At the same time Monitor is also responsible for promoting co-operation. HSCA 2012, section 66 (2) (e) states that Monitor must have regard to ‘the desirability of persons who provide health care services for the purposes of the NHS co-operating with each other in order to improve the quality of health care services provided for those purposes’. It is the role of NHS commissioners (including Clinical Commissioning Groups ‘CCGs’), however, to ensure that the appropriate levels of competition and cooperation exist in their local health economies (HSCA, 2012). Need for research While studies have noted that incentives for competition and cooperation exist in healthcare (Goddard and Mannion, 1998; Kurunmaki 1999), few have researched the interaction between the two. Although there is research about the effects of competition in the NHS reforms introduced by New Labour (e.g. Cooper et al, 2010; Gaynor et al, 2011), there remains a need to investigate the way in which local health systems are managed to ensure that cooperative behaviour is appropriately coexisting with competition. Some specific forms of cooperation have been evaluated 5 (such as integrated care organisations, DH 2009, and clinical networks, e.g. Ferlie et al, 2010), but it does not appear that the general manner in which local health systems are being managed to balance competition and cooperation under the current reforms is being investigated. Study of commissioning through competition and cooperation For this reason, PRUComm is undertaking a project to investigate how commissioners in local health systems manage the interplay of competition and cooperation in their local health economies, looking at acute and community health services (CHS). The research questions are: How do commissioners and the organisations they commission from understand the policy and regulatory environment, including incentives for competition and co-operation? In the current environment, which encourages both competition and cooperation, how do commissioning organisations and providers approach their relationships with each other in order to undertake the planning and delivery of care for patients? In particular, how do commissioning organisations use or shape the local provider environment to secure high quality care for patients? This entails examining how CCGs’ commissioning strategies take account of the local configuration of providers and the degree to which they seek to use or enhance competition and/or encourage cooperation to improve services. This interim report deals with the first research question concerning commissioners’ and providers’ respective understandings of the policy and regulatory environment in which they operate

Injection into Supersonic Boundary Layers

A method for injection of gas into the boundary layer on a slender body in supersonic flow while minimizing perturbation to the mean flow is examined. Injection of gas is equivalent to a sudden increase in the displacement thickness of the boundary layer, which produces an oblique shock that propagates into the inviscid region of the flow. It is found that modification of the geometry of the body can compensate for the increased displacement thickness created by injection and minimize the production of oblique waves. However, the resulting near-wall injection layer is observed to be unstable and a turbulent boundary layer develops downstream of the injection region. The instability of the flow is examined experimentally using high-speed schlieren visualization and numerically using linear stability analysis of velocity profiles from a compressible Navier–Stokes computation. At the present postshock Mach number of about 3.8, both first- and second-mode instabilities are active, though computations predict that the first mode is primarily responsible for transition downstream of the injector