Analytic bond-order potentials for the bcc refractory metals Nb, Ta, Mo and W.

Bond-order potentials (BOPs) are based on the tight-binding approximation for determining the energy of a system of interacting atoms. The bond energy and forces are computed analytically within the formalism of the analytic BOPs. Here we present parametrizations of the analytic BOPs for the bcc refractory metals Nb, Ta, Mo and W. The parametrizations are optimized for the equilibrium bcc structure and tested for atomic environments far from equilibrium that had not been included in the fitting procedure. These tests include structural energy differences for competing crystal structures; tetragonal, trigonal, hexagonal and orthorhombic deformation paths; formation energies of point defects as well as phonon dispersion relations. Our tests show good agreement with available experimental and theoretical data. In practice, we obtain the energetic ordering of vacancy, [1 1 1], [1 1 0], and [1 0 0] self-interstitial atom in agreement with density functional theory calculations.

[Mechanics and effects of European reference pricing for vaccines in Germany according to §130a Abs. 2 SGB V: an analysis using the example of influenza vaccines]. / Funktionsweise und Auswirkungen des Referenzpreissystems bei Impfstoffen nach §130a Abs. 2 SGB V: eine Analyse am Beispiel der Grippeimpfstoffe.

OBJECTIVES: On 01 January 2011 the bill for the reorganisation of the pharmaceutical market became effective. Since that time there is a European reference pricing (ERP) system for vaccines in order to bring down the German vaccine prices to an assumed lower European level. This study describes the implementation, functioning and effect of this new system. For influenza vaccines the impact of ERP on the price level and spread of prices is analysed. METHODS: The description of the mechanism is based on the law and corresponding regulations of the head association of sickness funds (GKV-SV). The analysis of vaccine prices is based on the data of the i:data report (status of 01 September 2011) of ifap Service Institute. RESULTS: The European reference price is calculated as the average price of the manufacturer-selling-prices of the corresponding vaccine in the 4 countries of the European Union whose gross national income comes closest to the German one and in which the vaccine is distributed. The relied prices are weighted by sales and purchasing power parities of the respective countries. This analysis suggests that in particular the practical implementation of the reference price system should be further improved and specified. The calculation of the reference prices should ensure price comparability. In addition, significant problems remain in the deduction of discounts, because no distinction is made in the documentation of vaccinating doctors, whether vaccination was performed as a compulsory or statutory benefit. The comparison of the manufacturer-selling-prices of individual influenza vaccines with the corresponding reference prices shows an enlargement of the existing price differences, which have evolved in a competitive environment, after the implementation of the reference pricing -system. CONCLUSIONS: There is still a need for improvement in implementing the reference pricing system. In the most competitive vaccine market of influenza vaccines, the ERP-system lowers the prices, but seems to distort the market prices.

Comparison of analytic and numerical bond-order potentials for W and Mo.

Bond-order potentials (BOPs) are derived from the tight-binding approximation and provide a linearly-scaling computation of the energy and forces for a system of interacting atoms. While the numerical BOPs involve the numerical integration of the response (Green's) function, the expressions for the energy and interatomic forces are analytical within the formalism of the analytic BOPs. In this paper we present a detailed comparison of numerical and analytic BOPs. We use established parametrizations for the bcc refractory metals W and Mo and test structural energy differences; tetragonal, trigonal, hexagonal and orthorhombic deformation paths; formation energies of point defects as well as phonon dispersion relations. We find that the numerical and analytic BOPs generally are in very good agreement for the calculation of energies. Different from the numerical BOPs, the forces in the analytic BOPs correspond exactly to the negative gradients of the energy. This makes it possible to use the analytic BOPs in dynamical simulations and leads to improved predictions of defect energies and phonons as compared to the numerical BOPs.

New superconducting and semiconducting Fe-B compounds predicted with an ab initio evolutionary search.

New candidate ground states at 1:4, 1:2, and 1:1 compositions are identified in the well-known Fe-B system via a combination of ab initio high-throughput and evolutionary searches. We show that the proposed oP12-FeB2 stabilizes by a break up of 2D boron layers into 1D chains while oP10-FeB4 stabilizes by a distortion of a 3D boron network. The uniqueness of these configurations gives rise to a set of remarkable properties: oP12-FeB2 is expected to be the first semiconducting metal diboride and oP10-FeB4 is shown to have the potential for phonon-mediated superconductivity with a T(c) of 15-20 K.

[Burden of acute rotavirus gastroenteritis (RV-AGE) in Germany: a comparison of federal statistics and epidemiological data]. / Krankheitslast durch akute Rotavirus-Gastroenteritis (RV-AGE) in Deutschland: Ein Vergleich offizieller Statistiken mit epidemiologischen Daten.

Worldwide, rotavirus (RV) is the main cause for morbidity and mortality due to acute gastroenteritis (AGE) among infants and toddlers. In Germany, where RV-AGE is notifiable, rotavirus is the most common pathogen of AGE in young children. Since 2006, two rotavirus vaccines for use in infants are available. The objective of this study is to estimate the burden of RV-AGE among young children in Germany on the basis of federal statistics as well as data from epidemio-logical studies. Between 2001 and 2004, 36,281 (or 37,932) RV infections among children below 4 (or 5 years) of age have been notified per year which results in an incidence of 1.2%/1%. Epidemiological studies yield an estimate of 117,985 cases of RV-AGE among children below 4 years of age (incidence: 4%). The hospital statistic shows 12,716 RV-AGE cases per year in children below the age of 5 years between 2001 and 2004. Those cases account for 22% of all AGE cases. However, the causative organism is not stated in more than 75% of cases. In epidemiological studies, an average of 53% of the hospitalised cases of AGEs has been attributed to RV. Based on these data, 30,500 hospitalized RV-AGE cases can be expected per year among children up to 5 years. The mortality statistics show less than one death due to RV among young children per year. Based on federal statistics as well as epidemiological studies, the burden of RV-AGE can only be estimated approximately. While federal statistics underestimate the burden of RV-AGE, the burden documented in epidemiological studies in young children is high in Germany. These findings support the recommendation of the Deutsche Akademie für Kinderheilkunde und Jugendmedizin (DAKJ) for a general vaccination of against RV in Germany.

[Adherence with daily and weekly administration of oral bisphosphonates for osteoporosis treatment]. / Adhärenz mit täglichen und wöchentlichen oralen Bisphosphonaten in der Osteoporosetherapie.

BACKGROUND AND OBJECTIVE: Bisphosphonates provide efficacious treatment for osteoporosis. However, side effects often lead to patients discontinuing this treatment. This study analyses differences in adherence (including acceptance, persistence and compliance) between daily (ALD-D) and weekly (ALD-W) administration of alendronate among German patients with osteoporosis. METHODS: Prescription claims data of two random groups of subjects (144 patients each) taking ALD-D and ALD-W, respectively, were observed for 12 months after starting the given prescription. Termination was defined as the moment when the last prescription had been used up. The percentage of patients continuing the drug treatment after the first prescription was used as a measure for acceptance. Compliance was measured by the medication possession ratio (MPR), namely the percentage of days on which the patient was supplied with the medication. An MPR > 80% is therapeutically relevant because the risk of fractures is significantly reduced. RESULTS: 31.3% (ALD-W) vs. 45.8% (ALD-D) of patients discontinued therapy after one prescription. 53.5% (ALD-W) vs. 72.2% (ALD-D) of patients discontinued therapy throughout the year. The proportion of those who discontinued the treatment was significantly higher with daily administration (p=0.0035). Mean time until discontinuation was 220 days (ALD-W) vs. 169 days (ALD-D). Mean compliance among any patients was 51.7% (ALD-W) vs. 37.7% (ALD-D); Only 30.6% (ALD-W) vs. 19.2% (ALD-D) (p=0,0295) of patients reached a therapeutically relevant compliance level. CONCLUSIONS: A large proportion of patients discontinued treatment with bisphosphonates, a majority of discontinuing patients not even refilling their first prescription. Adherence, although enhanced by less frequent dosing, was suboptimal in all of its aspects, i.e. acceptance, persistence and compliance. There is a need for treatment strategies to increase adherence.