Biomedical subjects
Publications and source records attributed to C Theis.
Randomized controlled trials were evaluated to assess the effectiveness of extracorporeal shock wave treatment in the management of tennis elbow. Five trials had a mediocre methodology and four trials had a high-quality design. Well-designed randomized control trials have provided evidence of the effectiveness of shock wave intervention for tennis elbow.
Monitoring of the radiation environment is one of the key tasks in operating a high-energy accelerator such as the Large Hadron Collider (LHC). The radiation fields consist of neutrons, charged hadrons as well as photons and electrons with energy spectra extending from those of thermal neutrons up to several hundreds of GeV. The requirements for measuring the dose equivalent in such a field are different from standard uses and it is thus necessary to investigate the response of monitoring devices thoroughly before the implementation of a monitoring system can be conducted. For the LHC, it is currently foreseen to install argon- and hydrogen-filled high-pressure ionisation chambers as radiation monitors of mixed fields. So far their response to these fields was poorly understood and, therefore, further investigation was necessary to prove that they can serve their function well enough. In this study, ionisation chambers of type IG5 (Centronic Ltd) were characterised by simulating their response functions by means of detailed FLUKA calculations as well as by calibration measurements for photons and neutrons at fixed energies. The latter results were used to obtain a better understanding and validation of the FLUKA simulations. Tests were also conducted at the CERF facility at CERN in order to compare the results with simulations of the response in a mixed radiation field. It is demonstrated that these detectors can be characterised sufficiently enough to serve their function as radiation monitors for the LHC.
The guidelines of the German Orthopaedic Societies regarding the treatment of lateral elbow epicondylitis were analysed on the ground of recently published reviews or randomised placebo-controlled trials (RCT). For the acute phase, reviews or RCTs failed to show a clinical effect beyond placebo if follow-up was extended over 6 weeks. For the chronic phase a current Cochrane review failed to identify any controlled trial regarding surgical procedures during the last decades. Without an adequate control group, it is not possible to draw any meaningful conclusions about the value of this modality of treatment. Therefore surgery is not indicated before repetitive low-energy extracorporeal shock wave therapy (ESWT) has been applied. This novel treatment, under strictly standardized conditions, showed effects beyond placebo in independent randomised placebo-controlled trials for follow-up periods of 3 and 6 months. To date there exists no evidence-based therapeutic algorithm for the treatment of acute and chronic tennis elbow. Even medium-term effects should be regarded as either a placebo effect or natural regression to the mean.
Forty-three consecutive patients who did not have healing of tibial or femoral diaphyseal and metaphyseal fractures and osteotomies for at least 9 months after injury or surgery were examined prospectively for use of high-energy extracorporeal shock waves. Former treatment modalities (cast, external fixator, plate osteosynthesis, limitation of weightbearing) remained unchanged. In all cases a 99mTechnetium dicarboxyphosphonate regional two-phase bone scintigraphy was performed before one treatment with 3,000 impulses of an energy flux density of 0.6 mJ/mm2. Radiologic and clinical followups were done at 4-week intervals starting 8 weeks after shock wave treatment. The success criterion was bridging of all four cortices in the anteroposterior and lateral radiographic views, in oblique views, or by conventional tomography. An independent observer described bony consolidation in 31 of 43 cases (72%) after an average of 4 months (range, 2-7 months). Twenty-nine of 35 (82.9%) patients with a positive bone scan had healing of the pseudarthrosis compared with two of eight (25%) patients with a negative bone scan. Six of these eight patients with negative scans were heavy smokers. No complications were observed. High-energy shock wave therapy seemed to be an effective noninvasive tool for stimulation of bone healing in properly selected patients with a diaphyseal or metaphyseal nonunion of the femur or tibia. Additional controlled studies are mandatory.
We report recent progress on the test of mode coupling theory for molecular liquids (MMCT) for molecules of arbitrary shape. The MMCT equations in the long time limit are solved for supercooled water including all molecular degrees of freedom. In contrast to our earlier treatment of water as a linear molecule, we find that the glass-transition temperature T(c) is overestimated by the theory as was found in the case of simple liquids. The nonergodicity parameters are calculated from the "full" set of MMCT equations truncated at l(co)=2. These results are compared (i) with the nonergodicity parameters from MMCT with l(co)=2 in the "dipole" approximation n=n(')=0 and the diagonalization approximation n=n(')=0, l=l(') and (ii) with the corresponding results from a MD simulation. This work supports the possibility that a reduction to the most prominent correlators may constitute a valid approximation for solving the MMCT equations for rigid molecules.
We present static and dynamic properties of molecular correlation functions S(lmn,l(')m(')n('))(q-->,t) in a simulated supercooled liquid of water molecules, as a preliminary effort in the direction of solving the molecular mode-coupling theory (MMCT) equations for supercooled molecular liquids. The temperature and time dependence of various molecular correlation functions, calculated from 250 ns long molecular dynamics simulations, show the characteristic patterns predicted by MMCT and shed light on the driving mechanism responsible for the slowing down of the molecular dynamics. We also discuss the symmetry properties of the molecular correlation functions that can be predicted on the basis of the C(2v) symmetry of the molecule. Analysis of the molecular dynamics results for the static correlators S(lmn,l(')m(')n('))(q-->) reveals that additional relationships between correlators with different signs of n and n(') exist. We prove that for molecules with C(rv) symmetry this unexpected result becomes exact at least for high temperatures.
We study the molecular mode-coupling theory for a liquid of diatomic molecules. The equations for the critical tensorial nonergodicity parameters F(m)(ll('))(q) and the critical amplitudes of the beta relaxation H(m)(ll('))(q) are solved up to a cutoff l(co)=2 without any further approximations. Here l,m are indices of spherical harmonics. Contrary to previous studies, where additional approximations were applied, we find in agreement with simulations that all molecular degrees of freedom vitrify at a single temperature T(c). The theoretical results for the nonergodicity parameters and the critical amplitudes are compared with those from simulations. The qualitative agreement is good for all molecular degrees of freedom. To study the influence of the cutoff on the nonergodicity parameter, we also calculate the nonergodicity parameters for an upper cutoff l(co)=4. In addition, we also propose a method for the calculation of the critical nonergodicity parameter from the liquid side of transition.
We present mode-coupling equations for the description of the slow dynamics observed in supercooled molecular liquids close to the glass transition. The mode-coupling theory (MCT) originally formulated to study the slow relaxation in simple atomic liquids, and then extended to the analysis of liquids composed by linear molecules, is here generalized to systems of arbitrarily shaped, rigid molecules. We compare the predictions of the theory for the q-vector dependence of the molecular nonergodicity parameters, calculated by solving numerically the molecular MCT equations in two different approximation schemes, with "exact" results calculated from a molecular dynamics simulation of supercooled water. The agreement between theory and simulation data supports the view that MCT succeeds in describing the dynamics of supercooled molecular liquids, even for network forming ones.
We show that the intermediate scattering function S(n)(q,t) for neutron scattering (ns) can be expanded naturally with respect to a set of molecular correlation functions that give a complete description of the translational and orientational two-point correlations in the liquid. The general properties of this expansion are discussed with special focus on the q dependence, and hints for a (partial) determination of the molecular correlation functions from neutron scattering results are given. The resulting representation of the static structure factor S(n)(q) is studied in detail for a model system using data from a molecular dynamics simulation of a supercooled liquid of rigid diatomic molecules. The comparison between the exact result for S(n)(q) and different approximations that result from a truncation of the series representation demonstrates its good convergence for the given model system. On the other hand it shows explicitly that the coupling between translational and orientational degrees of freedom of each molecule and rotational motion of different molecules cannot be neglected in the supercooled regime. Further we report the existence of a prepeak in the ns static structure factor of the examined fragile glass former, demonstrating that prepeaks can occur even in the most simple molecular liquids. Besides examining the dependence of the prepeak on the scattering length and the temperature we use the expansion of S(n)(q) into molecular correlation functions to point out the intermediate range orientational order as its principle origin.
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The nuclear carbohydrate-binding protein 35 (CBP35), a beta-galactoside-specific lectin with an M(r) of 35,000, has been identified in nuclear ribonucleoprotein complexes (RNPs) from a variety of mammalian tissues and cells. Here we determined that the expression of CBP35 mRNA greatly increases after infection of Molt-3 cells with human immunodeficiency virus type 1 (HIV-1), concomitantly with the onset of expression of the viral regulatory gene tat, and then declines. The increase in CBP35 mRNA level results in an enhanced synthesis of CBP35, as evidenced in nitrocellulose filter binding assay using radiolabeled, sugar-specific neoglycoprotein. Immunoblotting experiments showed that CBP35 is present in the 40S heterogeneous nuclear RNP complex from HIV-1-infected Molt-3 cells. CBP35 could also be detected using a novel photoreactive alpha-D-galactose probe designed for the specific detection of CBP.
A rare case of avoiding phenomenon presenting as transient ischemic attacks is reported. The distal anterior parietal artery was probably occluded.
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