Association between quality of clinical practice guidelines and citations given to their references

It has been suggested that bibliometric analysis of different document types may reveal new aspects of research performance. In medical research a number of study types play different roles in the research process and it has been shown, that the evidence-level of study types is associated with varying citation rates. This study focuses on clinical practice guidelines, which are supposed to gather the highest evidence on a given topic to give the best possible recommendation for practitioners. The quality of clinical practice guidelines, measured using the AGREE score, is compared to the citations given to the references used in these guidelines, as it is hypothesised, that better guidelines are based on higher cited references. AGREE scores are gathered from reviews of clinical practice guidelines on a number of diseases and treatments. Their references are collected from Web of Science and citation counts are normalised using the item-oriented z-score and the PPtop-10% indicators. A positive correlation between both citation indicators and the AGREE score of clinical practice guidelines is found. Some potential confounding factors are identified. While confounding cannot be excluded, results indicate low likelihood for the identified confounders. The results provide a new perspective to and application of citation analysis.Comment: Paper submitted to 14th International Society of Scientometrics and Informetrics Conferenc

Pension institutions and annuities in Denmark

This paper considers the overall structure of the Danish pension system, reviews the relative role of different types of pension institutions, and discusses their asset allocation strategies and investment performance. The paper also examines the regulation and supervision of providers of pension services, the growing reliance on risk-based supervision,and the application of the so-called contribution principle. The Danish pension system includes a modest universal social pension with a supplement for low-income pensioners and near universal participation in occupational and personal pensions that are primarily based on defined contribution plans. The annuity market is well developed: 50 percent of annual contributions are allocated to the purchase of deferred annuities, while immediate annuities are also purchased at or even after retirement. However, detailed comprehensive data on the rate of annuitization are lacking. Distinct features of the Danish pension system include the widespread use of profit participating contracts with minimum guaranteed benefits and regular provision of bonuses, covering both the accumulation and payout phases, and extensive use of group deferred annuity contracts. A new traffic light system with periodic stress testing has resulted in greater emphasis on asset liability matching and hedging strategies by pension institutions and a shift in investment policies in favor of foreign bonds and long-term swap contracts.,Debt Markets,Emerging Markets,Pensions&Retirement Systems,Insurance&Risk Mitigation

The linkage principle for restricted critical level representations of affine Kac-Moody algebras

We study the restricted category O for an affine Kac--Moody algebra at the critical level. In particular, we prove the first part of the Feigin-Frenkel conjecture: the linkage principle for restricted Verma modules. Moreover, we prove a version of the BGGH-reciprocity principle and we determine the block decomposition of the restricted category O. For the proofs we need a deformed version of the classical structures, so we mostly work in a relative setting.Comment: 25 pages, substantially revised version, closing a gap in the earlier version

Magnetic phase diagram of the iron pnictides in the presence of spin-orbit coupling: Frustration between C2C_2 and C4C_4 magnetic phases

We investigate the impact of spin anisotropic interactions, promoted by spin-orbit coupling, on the magnetic phase diagram of the iron-based superconductors. Three distinct magnetic phases with Bragg peaks at $(\pi,0)$ and $(0,\pi)$ are possible in these systems: one $C_2$ (i.e. orthorhombic) symmetric stripe magnetic phase and two $C_4$ (i.e. tetragonal) symmetric magnetic phases. While the spin anisotropic interactions allow the magnetic moments to point in any direction in the $C_2$ phase, they restrict the possible moment orientations in the $C_4$ phases. As a result, an interesting scenario arises in which the spin anisotropic interactions favor a $C_2$ phase, but the other spin isotropic interactions favor a $C_4$ phase. We study this frustration via both mean-field and renormalization-group approaches. We find that, to lift this frustration, a rich magnetic landscape emerges well below the magnetic transition temperature, with novel $C_2$, $C_4$, and mixed $C_2$-$C_4$ phases. Near the putative magnetic quantum critical point, spin anisotropies promote a stable Gaussian fixed point in the renormalization-group flow, which is absent in the spin isotropic case, and is associated with a near-degeneracy between $C_2$ and $C_4$ phases. We argue that this frustration is the reason why most $C_4$ phases in the iron pnictides only appear inside the $C_2$ phase, and discuss additional manifestations of this frustration in the phase diagrams of these materials.Comment: 21 pages, 19 figures, published versio

The recurrence time of Dansgaard-Oeschger events and limits on the possible periodic component

By comparing the high-resolution isotopic records from the GRIP and NGRIP icecores, we approximately separate the climate signal from local noise to obtain an objective criterion for defining Dansgaard-Oeschger events. Our analysis identifies several additional short lasting events, increasing the total number of DO events to 27 in the period 12-90 kyr BP. The quasi-regular occurrence of the DO events could indicate a stochastic or coherent resonance mechanism governing their origin. From the distribution of waiting times we obtain a statistical upper bound on the strength of a possible periodic forcing. This finding indicates that the climate shifts are purely noise driven with no underlying periodicity.Comment: 9 figure

Chemical Transformation Motifs - Modelling Pathways as Integer Hyperflows

We present an elaborate framework for formally modelling pathways in chemical reaction networks on a mechanistic level. Networks are modelled mathematically as directed multi-hypergraphs, with vertices corresponding to molecules and hyperedges to reactions. Pathways are modelled as integer hyperflows and we expand the network model by detailed routing constraints. In contrast to the more traditional approaches like Flux Balance Analysis or Elementary Mode analysis we insist on integer-valued flows. While this choice makes it necessary to solve possibly hard integer linear programs, it has the advantage that more detailed mechanistic questions can be formulated. It is thus possible to query networks for general transformation motifs, and to automatically enumerate optimal and near-optimal pathways. Similarities and differences between our work and traditional approaches in metabolic network analysis are discussed in detail. To demonstrate the applicability of the mathematical framework to real-life problems we first explore the design space of possible non-oxidative glycolysis pathways and show that recent manually designed pathways can be further optimised. We then use a model of sugar chemistry to investigate pathways in the autocatalytic formose process. A graph transformation-based approach is used to automatically generate the reaction networks of interest