Improvement in the decadal prediction skill of the North Atlantic extratropical winter circulation through increased model resolution

In this study the latest version of the MiKlip decadal hindcast system is analyzed, and the effect of an increased horizontal and vertical resolution on the prediction skill of the extratropical winter circulation is assessed. Four different metrics – the storm track, blocking, cyclone and windstorm frequencies – are analyzed in the North Atlantic and European region. The model bias and the deterministic decadal hindcast skill are evaluated in ensembles of five members in a lower-resolution version (LR, atm: T63L47, ocean: 1.5∘ L40) and a higher-resolution version (HR, atm: T127L95, ocean: 0.4∘ L40) of the MiKlip system based on the Max Planck Institute Earth System model (MPI-ESM). The skill is assessed for the lead winters 2–5 in terms of the anomaly correlation of the quantities' winter averages using initializations between 1978 and 2012. The deterministic predictions are considered skillful if the anomaly correlation is positive and statistically significant. While the LR version shows common shortcomings of lower-resolution climate models, e.g., a storm track that is too zonal and southward displaced as well as a negative bias of blocking frequencies over the eastern North Atlantic and Europe, the HR version counteracts these biases. Cyclones, i.e., their frequencies and characteristics like strength and lifetime, are particularly better represented in HR. As a result, a chain of significantly improved decadal prediction skill between all four metrics is found with the increase in the spatial resolution. While the skill of the storm track is significantly improved primarily over the main source region of synoptic activity – the North Atlantic Current – the other extratropical quantities experience a significant improvement primarily downstream thereof, i.e., in regions where the synoptic systems typically intensify. Thus, the skill of the cyclone frequencies is significantly improved over the central North Atlantic and northern Europe, the skill of the blocking frequencies is significantly improved over the Mediterranean, Scandinavia and eastern Europe, and the skill of the windstorms is significantly improved over Newfoundland and central Europe. Not only is the skill improved with the increase in resolution, but the HR system itself also exhibits significant skill over large areas of the North Atlantic and European sector for all four circulation metrics. These results are particularly promising regarding the high socioeconomic impact of European winter windstorms and blocking situations

Independent Information of Nonspecific Biomarkers in Exhaled Breath Condensate

Background: Exhaled breath condensate (EBC) has been used for diagnosing and monitoring respiratory disorders. For clinical purposes the assessment of easy-to-obtain nonspecific markers seems particularly interesting. Objectives: As these measures are related to each other, our objective was to extract the independent information in global EBC markers across a range of respiratory disorders. Methods: EBC was collected from patients with asthma (n = 18), chronic obstructive pulmonary disease (n = 17), and cystic fibrosis (n = 46), as well as from lung transplant (LTX) recipients (n = 14) and healthy controls (n = 26). Samples were assessed for electrical conductivity, ammonia, pH, and nitrite/nitrate. pH was measured after both deaeration with argon and CO(2) standardization. Additionally, the fraction of exhaled nitric oxide (FE(NO)) was assessed. Factor analysis was applied to identify major factors concerning these measures. Results: Three independent factors were detected; the first comprised conductivity, ammonia, and pH, especially when standardized using CO(2), the second nitrite/nitrate, and the third FE(NO). Conductivity and ammonia were highly correlated (r = 0.968; p < 0.001). FE(NO) provided independent information mainly in asthma. The nonspecific EBC markers showed considerable overlap between patient groups and healthy subjects. However, conductivity, ammonia, pH standardized for CO(2) and nitrite/nitrate were increased in LTX recipients compared to healthy controls (p < 0.05 each). Conclusions: A panel of nonspecific easy-to-obtain exhaled breath markers could be reduced to 3 independent factors. The information content of conductivity, ammonia, and pH after CO(2) equilibration appeared to be similar, while FE(NO) was independent. The increased levels of these biomarkers in LTX might indicate a potential for their use in these patients. Copyright (C) 2010 S. Karger AG, Base

Longitudinal beam dynamics for different initial distributions at cSTART

The compact STorage ring for Accelerator Research and Technology (cSTART) project aims to store electron bunches of LPA-like beams in a very large momentum acceptance storage ring. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for cSTART to benchmark and emulate laser-plasma accelerator-like beams. In a second stage a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and Helmholtz Institute Jena (HIJ). With an energy of 50 MeV and damping times of several seconds, the electron beam does not reach equilibrium emittance within the storage time of about 100 milliseconds. Therefore, the initial phase space distribution influences the later dynamics and beam properties. We perform longitudinal particle tracking simulations to investigate the evolution of the bunch lengths and phase space densities for different initial beam distributions

Chewing simulation of zirconia implant supported restorations

PURPOSE To test three potential prosthetic material options for zirconia implants in regard to their mechanical properties, loading and retention capacity as well as to record abrasion after chewing simulation followed by thermocyclic aging. METHODS Molar crowns (n = 96) of three different computer-aided design/computer-aided manufacturing (CAD/CAM) materials were produced and cemented on zirconia implants (ceramic.implant, Vita) with a diameter of 4.5 mm. Monolithic zirconia (Vita YZ [YZ] with RelyX Unicem 2 Automix [RUN], polymer-infiltrated ceramic (Vita Enamic [VE]) with Vita Adiva F-Cem [VAF] and acrylate polymer (CAD Temp [CT]) with RelyX Ultimate [RUL]. Fracture load and retentive force of the crowns were measured after 24 h water storage at 37 °C and after a chewing simulation followed by thermocyclic aging. Abrasion was recorded by matching stereolithography-data of the crowns obtained before and after chewing simulation. Additionally, the mechanical properties and bonding capabilities of the crown and cement materials were assessed. RESULTS Fracture load values were significantly highest for YZ > VE = CT. Retention force values did not differ significantly between the materials. The aging procedure did not affect the fracture load values nor the retention force significantly. Abrasion depth of the crowns was lowest for YZ followed by VE and CT. On unpolished crowns, abrasion of YZ and VE tended to be higher than on polished specimens. CONCLUSIONS Based on the obtained in-vitro results, all tested materials can be recommended for the use on zirconia implants, although CT is only approved for temporary crowns. The loading and retention capacity of the materials were not significantly affected by aging

The Hamiltonian of the V15_{15} Spin System from first-principles Density-Functional Calculations

We report first-principles all-electron density-functional based studies of the electronic structure, magnetic ordering and anisotropy for the V$_{15}$ molecular magnet. From these calculations, we determine a Heisenberg Hamiltonian with four antiferromagnetic and one {\em ferromagnetic} coupling. We perform direct diagonalization to determine the temperature dependence of the susceptibility. This Hamiltonian reproduces the experimentally observed spin $S$=1/2 ground state and low-lying $S$=3/2 excited state. A small anisotropy term is necessary to account for the temperature independent part of the magnetization curve.Comment: 4 pages in RevTeX format + 2 ps-figures, accepted by PRL Feb. 2001 (previous version was an older version of the paper

Impact of geometry on chemical analysis exemplified for photoelectron spectroscopy of black silicon

For a smooth surface, the chemical composition can be readily evaluated by a variety of spectroscopy techniques; a prominent example is X-ray photoelectron spectroscopy (XPS), where the relative proportions of the elements are mainly determined by the intensity ratio of the element-specific photoelectrons. This deduction, however, is more intricate for a nanorough surface, such as black silicon, since the steep slopes of the geometry mimic local variations of the local emission angle. Here, we explicitly quantify this effect via an integral geometric analysis, by using so-called Minkowski tensors. Thus, we match the chemical information from XPS with topographical information from atomic force microscopy (AFM). Our method provides reliable estimates of layer thicknesses for nanorough surfaces. For our black silicon samples, we found that the oxide layer thickness is on average comparable to that of a native oxide layer. Our study highlights the impact of complex geometries at the nanoscale on the analysis of chemical properties with implications for a broad class of spectroscopy techniques