Realistic Interactions and Dilepton production off pp-collisions

We present a model for dilepton production of proton-proton collisions using a realist T-matrix that by incorporating Delta-isobar degrees of freedom fits the NN-scattering data up to 2 GeV. The results we find differ in details from earlier work that use less sophisticated interactions but the overall agreement with these calculations is good.Comment: 11 pages Revtex, 2 postscript figures include

Dilepton Production in Nucleon-Nucleon Interactions

Starting from a realistic one--boson--exchange--model fitted to the amplitudes of elastic nucleon--nucleon scattering and the process $NN\rightarrow N\Delta$ we perform a fully relativistic and gauge invariant calculation for the dilepton production in nucleon--nucleon collisions, including the important effect of propagating the $\Delta$--resonance. We compare the results of our calculations with the latest experimental data on dilepton production. We also show how to implement various electromagnetic formfactors for the hadrons in our calculations without loosing gauge--invariance and discuss their influence on dilepton spectra.Comment: 24 pages, figures will be sent on reques

A new MRI rating scale for progressive supranuclear palsy and multiple system atrophy: validity and reliability

AIM To evaluate a standardised MRI acquisition protocol and a new image rating scale for disease severity in patients with progressive supranuclear palsy (PSP) and multiple systems atrophy (MSA) in a large multicentre study. METHODS The MRI protocol consisted of two-dimensional sagittal and axial T1, axial PD, and axial and coronal T2 weighted acquisitions. The 32 item ordinal scale evaluated abnormalities within the basal ganglia and posterior fossa, blind to diagnosis. Among 760 patients in the study population (PSP = 362, MSA = 398), 627 had per protocol images (PSP = 297, MSA = 330). Intra-rater (n = 60) and inter-rater (n = 555) reliability were assessed through Cohen's statistic, and scale structure through principal component analysis (PCA) (n = 441). Internal consistency and reliability were checked. Discriminant and predictive validity of extracted factors and total scores were tested for disease severity as per clinical diagnosis. RESULTS Intra-rater and inter-rater reliability were acceptable for 25 (78%) of the items scored (≥ 0.41). PCA revealed four meaningful clusters of covarying parameters (factor (F) F1: brainstem and cerebellum; F2: midbrain; F3: putamen; F4: other basal ganglia) with good to excellent internal consistency (Cronbach α 0.75-0.93) and moderate to excellent reliability (intraclass coefficient: F1: 0.92; F2: 0.79; F3: 0.71; F4: 0.49). The total score significantly discriminated for disease severity or diagnosis; factorial scores differentially discriminated for disease severity according to diagnosis (PSP: F1-F2; MSA: F2-F3). The total score was significantly related to survival in PSP (p<0.0007) or MSA (p<0.0005), indicating good predictive validity. CONCLUSIONS The scale is suitable for use in the context of multicentre studies and can reliably and consistently measure MRI abnormalities in PSP and MSA. Clinical Trial Registration Number The study protocol was filed in the open clinical trial registry (http://www.clinicaltrials.gov) with ID No NCT00211224

Experimental investigation and numerical description of the damage evolution in a duplex stainless steel subjected to VHCF-loading

The present study documents how the irreversible fraction of cyclic plastic strain, induced by loading amplitudes close to the durability limit, causes fatigue damage such as (i) slip band development, (ii) fatigue crack initiation and (iii) short fatigue crack propagation. The damage evolution of the austenitic-ferritic duplex stainless steel X2CrNiMoN22-5-3 (318 LN) was investigated up to one billion load cycles by means of high resolution electron microscopy (HR-SEM, TEM), focused ion beam (FIB) cutting, confocal laser scanning microscopy (CLSM), in-situ far field microscopy and high-energy (87.1 keV) X-ray diffraction (XRD) experiments. The experimentally identified damage mechanisms were implemented into three-dimensional finite element simulations, which consider crystal plasticity. These simulations enable fatigue life predictions of real microstructures obtained for instance by means of, e.g. automated electron back scatter diffraction (EBSD) analysis. The simulations allow for determining whether microcracks (i) initiate in a microstructure, (ii) arrest in the midst of the first grain, (iii) are permanently, (iv) temporary or (v) not at all blocked by grain or phase boundaries. Moreover, this concept is capable to contribute to the concept of tailored microstructures for improved cyclic-loading behaviour