The solvability of groups with nilpotent minimal coverings

A covering of a group is a finite set of proper subgroups whose union is the whole group. A covering is minimal if there is no covering of smaller cardinality, and it is nilpotent if all its members are nilpotent subgroups. We complete a proof that every group that has a nilpotent minimal covering is solvable, starting from the previously known result that a minimal counterexample is an almost simple finite group

Absolute and convective instabilities in non-local active-dissipative equations arising in the modelling of thin liquid films

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Absolute and convective instabilities in a non-local model that arises in the analysis of thin-film flows over flat or corrugated walls in the presence of an applied electric field are discussed. Electrified liquid films arise, for example, in coating processes where liquid films are deposited onto a target surfaces with a view to producing an evenly coating layer. In practice, the target surface, or substrate, may be irregular in shape and feature corrugations or indentations. This may lead to non-uniformities in the thickness of the coating layer. Attempts to mitigate film-surface irregularities can be made using, for example, electric fields. We analyse the stability of such thin-film flows and show that if the amplitude of the wall corrugations and/or the strength of the applied electric field is increased the convectively unstable flow undergoes a transition to an absolutely unstable flow

Confidence regions for the multinomial parameter with small sample size

Consider the observation of n iid realizations of an experiment with d>1 possible outcomes, which corresponds to a single observation of a multinomial distribution M(n,p) where p is an unknown discrete distribution on {1,...,d}. In many applications, the construction of a confidence region for p when n is small is crucial. This concrete challenging problem has a long history. It is well known that the confidence regions built from asymptotic statistics do not have good coverage when n is small. On the other hand, most available methods providing non-asymptotic regions with controlled coverage are limited to the binomial case d=2. In the present work, we propose a new method valid for any d>1. This method provides confidence regions with controlled coverage and small volume, and consists of the inversion of the "covering collection"' associated with level-sets of the likelihood. The behavior when d/n tends to infinity remains an interesting open problem beyond the scope of this work.Comment: Accepted for publication in Journal of the American Statistical Association (JASA

Absolute and convective instabilities in non-local active-dissipative equations arising in the modelling of thin liquid films

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Absolute and convective instabilities in a non-local model that arises in the analysis of thin-film flows over flat or corrugated walls in the presence of an applied electric field are discussed. Electrified liquid films arise, for example, in coating processes where liquid films are deposited onto a target surfaces with a view to producing an evenly coating layer. In practice, the target surface, or substrate, may be irregular in shape and feature corrugations or indentations. This may lead to non-uniformities in the thickness of the coating layer. Attempts to mitigate film-surface irregularities can be made using, for example, electric fields. We analyse the stability of such thin-film flows and show that if the amplitude of the wall corrugations and/or the strength of the applied electric field is increased the convectively unstable flow undergoes a transition to an absolutely unstable flow

Antinucleus Production at RHIC

Light antinuclei may be formed in relativistic heavy ion collisions via final state coalescence of antinucleons. The yields of antinuclei are sensitive to primordial antinucleon production, the volume of the system at kinetic freeze-out, and space-momentum correlations among antinucleons at freeze-out. We report here preliminary STAR results on antideuteron and antihelion production in 130A GeV Au+Au collisions. These results are examined in a coalescence framework to elucidate the space-time structure of the antinucleon source.Comment: 4 pages, 3 figures, talk given at Quark Matter 200

Expectations and experiences of gamete donors and donor-conceived adults searching for genetics relatives using DNA linking through a voluntary register

STUDY QUESTION: What are the experiences of donor-conceived adults and donors who are searching for a genetic link through the use of a DNA-based voluntary register service? SUMMARY ANSWER: Donor-conceived adults and donors held positive beliefs about their search and although some concerns in relation to finding a genetically linked relative were reported, these were not a barrier to searching. WHAT IS KNOWN ALREADY: Research with donor-conceived people has consistently identified their interest in learning about-and in some cases making contact with-their donor and other genetic relatives. However, donor-conceived individuals or donors rarely have the opportunity to act on these desires. STUDY DESIGN, SIZE, AND DURATION: A questionnaire was administered for online completion using Bristol Online Surveys. The survey was live for 3 months and responses were collected anonymously. PARTICIPANTS/MATERIALS, SETTING, AND METHODS: The survey was completed by 65 donor-conceived adults, 21 sperm donors and 5 oocyte donors who had registered with a DNA-based voluntary contact register in the UK. The questionnaire included socio-demographic questions, questions specifically developed for the purposes of this study and the standardized Aspects of Identity Questionnaire (AIQ). MAIN RESULTS AND THE ROLE OF CHANCE: Motivations for searching for genetic relatives were varied, with the most common reasons being curiosity and passing on information. Overall, participants who were already linked and those awaiting a link were positive about being linked and valued access to a DNA-based register. Collective identity (reflecting self-defining feelings of continuity and uniqueness), as assessed by the AIQ, was significantly lower for donor-conceived adults when compared with the donor groups (P 0.05) for donor-conceived adults. LIMITATIONS, REASONS FOR CAUTION: Participants were members of a UK DNA-based registry which is unique. It was therefore not possible to determine how representative participants were of those who did not register for the service, those in other countries or of those who do not seek information exchange or contact. WIDER IMPLICATIONS OF THE FINDINGS: This is the first survey exploring the experiences of donor-conceived adults and donors using a DNA-based voluntary register to seek information about and contact with genetic relatives and the first to measure aspects of identity using standardized measures. Findings provide valuable information about patterns of expectations and experiences of searching through DNA linking, identity and of having contact in the context of donor conception that will inform future research, practice and policy development

Systematic analysis of the evolution of electricity and carbon markets under deep decarbonization

The decarbonization of electricity generation presents policy makers in many countries with the delicate task of balancing initiatives for technological change with a commitment to market liberalization. Despite the theoretical attractions, it has become doubtful whether carbon markets by themselves can offer the desired solution. We address this question through an integrated modeling framework, stylized for the Great Britain (GB) power market within the EU ETS, which includes three distinct components: (a) long-term least-cost capacity planning, similar in functionality to many used in policy analysis, but innovative in providing the endogenous calculation of carbon prices; (b) short-term price risk analysis producing hourly dispatch and pricing outputs, which are used to test the annual financial performance metrics implied by the longer-term investments; and (c) agent-based computational learning to derive pricing behavior in imperfect markets. The results indicate that the risk/return profile of electricity markets may deteriorate substantially as a result of decarbonization, reducing the propensity of companies to invest in the absence of increased government support and/or more beneficial market circumstances. If allowed, markets may adjust by deferring investment until conditions improve, consolidating to increase market power, or operating in a tighter market with reduced spare capacity. To the extent that each of these “market-led” solutions may be politically unpalatable, policy design will need to sustain a delicate regulatory regime, moderating the possible increased market power of companies while maintaining low-carbon subsidies for longer than expected. This paper considers some of the modeling implications for this compromise

Evaluation of work-related psychosocial factors and regional musculoskeletal pain: results from a EULAR Task Force

Objectives: to establish whether review articles provide consistent conclusions on associations between workplace psychosocial factors and musculoskeletal pain and, if differences exist, to explore whether this is related to the methods used.Methods: reviews, reported up to February 2007, that included consideration of workplace psychosocial factors and upper limb, back or knee pain were identified through searches of multiple databases. The specific work-related psychosocial factors considered were job demands, support, job autonomy and job satisfaction. The conclusions of each review on one or more of the psychosocial/musculoskeletal pain associations were extracted.Results: 15 review articles were identified that considered one or more of the regional pain syndromes included in the study. For back pain, the most consistent conclusions (four reviews positive out of six) were with high job demands and low job satisfaction. The studies of upper limb pain were exclusively related to shoulder and/or neck pain, and the most consistent positive conclusions were with high and low job demands (four reviews positive out of six and two reviews positive out of three, respectively). For knee pain, only a single review was identified. For individual reviews of back and upper limb pain, there were marked differences in the number of associations concluded to be positive between reviews.Conclusions: the reasons for reviews coming to different conclusions included that they were often evaluating different bodies of evidence (according to their search criteria, the year when the review was conducted, the role that quality assessment played in whether studies contributed to evidence, and the combination of risk factors addressed in individual studies), but more important was whether the review specified explicit criteria for making conclusions on strength of evidence. These conclusions emphasise the importance of developing standardised methods for conducting such evaluations of existing evidence and the importance of new longitudinal studies for clarifying the temporal relationship between psychosocial factors and musculoskeletal pain in the workplac