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Search Results: 1 - 10 of 45300 matches for " Michael Koller "
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Infrared Spectroscopic Study of Phase Transisions in A1c60 Compounds (a=K,Rb,Cs)
Daniel Koller,Michael C. Martin,Laszlo Mihaly
Physics , 1994,
Abstract: Optical measurements on doped C$_{60}$ films provide evidence for a transition from a high temperature conducting phase to a low temperature insulating phase in quenched Rb$_1$C$_{60}$ and K$_1$C$_{60}$ compounds, while Cs$_1$C$_{60}$ did not exhibit this behavior. For slow cooled samples our study confirms earlier results indicating phase separation of K$_1$C$_{60}$ to K$_3$C$_{60}$ and C$_{60}$, and the formation of a new Rb$_1$C$_{60}$ phase at low temperatures. Upon slow cooling Cs$_1$C$_{60}$ behaves similar to Rb$_1$C$_{60}$.
In-Situ Infrared Transmission Study of Rb- and K-Doped Fullerenes
Michael C. Martin,Daniel Koller,L. Mihaly
Physics , 1993, DOI: 10.1103/PhysRevB.47.14607
Abstract: We have measured the four IR active $C_{60}$ molecular vibrations in $M_{x}C_{60}$ $(M = K, Rb)$ as a function of doping $x$. We observe discontinuous changes in the vibrational spectra showing four distinct phases (presumably $x = 0, 3, 4$, and 6). The $1427cm^{-1}$ and $576cm^{-1}$ modes show the largest changes shifting downward in frequency in four steps as the doping increases. Several new very weak modes are visible in the $x=6$ phase and are possibly Raman modes becoming weakly optically active. We present quantitative fits of the data and calculate the electron-phonon coupling of the $1427cm^{-1}$ IR mode.
Elbow Dislocations: A Review Ranging from Soft Tissue Injuries to Complex Elbow Fracture Dislocations
Carsten Englert,Johannes Zellner,Michael Koller,Michael Nerlich,Andreas Lenich
Advances in Orthopedics , 2013, DOI: 10.1155/2013/951397
Abstract: This review on elbow dislocations describes ligament and bone injuries as well as the typical injury mechanisms and the main classifications of elbow dislocations. Current treatment concepts of simple, that is, stable, or complex unstable elbow dislocations are outlined by means of case reports. Special emphasis is put on injuries to the medial ulnar collateral ligament (MUCL) and on posttraumatic elbow stiffness. 1. Introduction Even simple elbow dislocations do not necessarily represent benign injuries. Anakwe showed in a retrospective trial with almost 180 patients that simple elbow dislocations caused considerable residual pain and stiffness in 62% and 56% of the patients, respectively [1]. According to Anakwe, elbow dislocations can be defined as simple if an elbow is stable when put through full range of motion after repositioning. Typically, simple elbow dislocations occur when a person falls onto an outstretched hand. Axial compression on the elbow in combination with supination and valgus stress primarily result in the rupture of the lateral ulnar collateral ligament (LUCL), which may cause posterolateral subluxation (Figure 1(a)). Extended elbow dislocations often involve severe ruptures with anterior and posterior capsule distractions followed by muscle injuries and, finally, by total elbow dislocation with rupture of the anterior MUCL (Figure 1(b)). This ligament tends to rupture in two stages; that is, the rupture of the posterior MUCL (Figure 1(a)) is followed by the rupture of the anteromedial bundle of the ligament complex [2, 3] (Figure 1(b)). This trauma mechanism has been described by O’Driscoll, who has also classified posttraumatic elbow instability according to the following five criteria: the articulations involved, the direction of the displacement, the degree of the displacement, the timing, and the presence or absence of associated fractures [3]. Fractures of a bony structure with a buttress function immediately result in elbow instability. The function of the medial ulnar collateral ligament complex and particularly its role in complex elbow dislocations has been investigated intensively. However, single injuries to the MUCL seem to be rare. Figure 1: (a) Dorsal view to an anatomic elbow preparation. The posterior lateral ulnar collateral ligament (LUCL) and the posterior medial ulnar collateral ligament (MUCL) are visible. The posterior part of the ligamentum annulare with its insertion to the ulnar and the above lying distal part of the LCL can be seen. (b) Ventral view to an anatomic elbow preparation with demonstration of
Preoperative information for ICU patients to reduce anxiety during and after the ICU-stay: protocol of a randomized controlled trial [NCT00151554]
Almuth Berg, Steffen Fleischer, Michael Koller, Thomas R Neubert
BMC Nursing , 2006, DOI: 10.1186/1472-6955-5-4
Abstract: The trial is designed as a prospective randomized controlled trial including an intervention and a control group. The control group receives the standard preparation currently conducted by surgeons and anesthetists. The intervention group additionally receives a standardized information program with specific procedural, sensory and coping information about the ICU.A measurable clinical relevant difference regarding anxiety will be expected after discharge from ICU. Power calculation (α = 0.05; β = 0.20; Δ = 8.50 score points) resulted in a required sample size of N = 120 cardiac surgical patients (n = 60 vs. n = 60). Furthermore, N = 20 abdominal or thoracic surgical patients will be recruited (n = 10 vs. n = 10) to gain insight to a possible generalization to other patient groups.Additionally the moderating effect of specific patient attributes (need for cognition, high trait anxiety) will be investigated to identify certain patient groups which benefit most.The proposed study promises to strengthen evidence on effects of a specific, concise information program that addresses the information needs of patients scheduled for ICU stay.Technological advances during the last decades in intensive care medicine made it possible to treat an increasing number of high risk surgical patients. Nevertheless, many patients awaiting elective surgery experience diffuse anxiety and a lack of subjective predictability regarding their stay on the intensive care unit. The psychological elements that become salient in the perioperative situation can be characterized as loss of control, irritation and uncertainty. These psychological elements are also known for contributing to postoperative complications such as delayed wound healing and an increased intake of sedatives and analgesics [1]. In addition, the strange and unfamiliar situation on the ICU in combination with sleep deprivation and ICU-noises is closely related with the incidence of a postoperative delirium also called ICU-Synd
[μ-Bis(diphenylphosphanyl)methane]tricarbonyl(μ-p-toluenesulfonylmethyl isocyanato)(triphenylphosphane)ironplatinum(Fe—Pt)
Isabelle Jourdain,Michael Knorr,Stephan G. Koller,Carsten Strohmann
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812004023
Abstract: The title compound, [FePt(C9H9NO2S)(C18H15P)(C25H22P2)(CO)3], represents a rare example of an isonitrile-bridged heterobimetallic complex (here Pt and Fe) and is an interesting precursor for the preparation of heterodinuclear μ-aminocarbyne complexes, since the basic imine-type N atom of the μ2-C=N–R ligand readily undergoes addition with various electrophiles to afford iminium-like salts. In the crystal, the almost symmetrically bridging μ2-C=N-R ligand (neglecting the different atomic radii of Fe and Pt) is strongly bent towards the Fe(CO)3 fragment, with a C=N-R angle of only 121.1 (4)°.
Tinnitus assessment by means of standardized self-report questionnaires: Psychometric properties of the Tinnitus Questionnaire (TQ), the Tinnitus Handicap Inventory (THI), and their short versions in an international and multi-lingual sample
Zeman Florian,Koller Michael,Schecklmann Martin,Langguth Berthold
Health and Quality of Life Outcomes , 2012, DOI: 10.1186/1477-7525-10-128
Abstract: Background Tinnitus research in an international context requires standardized and validated questionnaires in different languages. The aim of the present set of analyses was the reassessment of basic psychometric properties according to classical test theory of self-report instruments that are being used within the multicentre Tinnitus Research Initiative (TRI) database project. Methods 1318 patients of the TRI Database were eligible for the analyses. The basic psychometric properties reliability, validity, and sensitivity of Tinnitus Handicap Inventory (THI), Tinnitus Questionnaire (TQ) and Tinnitus Beeintr chtigungs Fragebogen (i.e., Tinnitus Impairment Questionnaire, TBF-12) were assessed by the use of Cronbach’s alpha, corrected item-total correlations, correlation coefficients and standardized response means. Results Throughout the languages, all questionnaires showed high internal consistencies (Cronbach’s alpha > 0.79) and solid item-total correlations, as well as high correlations among themselves (around 0.8) and in combination with the self-reported tinnitus severity. However, some paradoxical correlations between individual items of the TBF-12, constructed as a shortform of the THI, and the corresponding THI-items were seen. Standardized Response Means (SRM) were low if tinnitus did not change, and between 0.3 and 1.09 for improved or worsened tinnitus complaints, indicating the sensitivity of the measures. Conclusions All investigated instruments have high internal consistency, high convergence and discriminant validity and good change sensitivity in an unselected large multinational clinical sample and thus appear appropriate to evaluate the effects of tinnitus treatments in a cross-cultural context.
Comprehensive Geriatric Assessment (CGA) in general practice: Results from a pilot study in Vorarlberg, Austria
Eva Mann, Michael Koller, Christian Mann, Tischa van der Cammen, Johann Steurer
BMC Geriatrics , 2004, DOI: 10.1186/1471-2318-4-4
Abstract: We developed and pilot tested a German language geriatric assessment instrument adapted for general practice. Nine general practices in a rural region of Austria participated in this cross-sectional study and consecutively enrolled 115 persons aged over 75 years. The prevalence of specific geriatric problems was assessed, as well as the frequency of initiated procedures following positive and negative tests. Whether findings were new to the physician was studied exemplarily for the items visual and hearing impairment and depression. The acceptability was recorded by means of self-administered questionnaires.On average, each patient reported 6.4 of 14 possible geriatric problems and further consequences resulted in 43.7% (27.5% to 59.8%) of each problem.The items with either the highest prevalence and/or the highest number of initiated actions by the GPs were osteoporosis risk, urinary incontinence, decreased hearing acuity, missing pneumococcal vaccination and fall risk. Visual impairment was newly detected in only 18% whereas hearing impairment and depression was new to the physician in 74.1% and 76.5%, respectively.A substantial number of interventions were initiated not only following positive tests (43.7% per item; 95% CI 27.5% to 59.8%), but also as a consequence of negative test results (11.3% per item; 95% CI 1.7% to 20.9%).The mean time expenditure to accomplish the assessment was 31 minutes (SD 10 min). Patients (89%) and all physicians confirmed the CGA to provide new information in general on the patient's health status. All physicians judged the CGA to be feasible in everyday practice.This adapted CGA was feasible and well accepted in the general practice sample. High frequencies of geriatric problems were detected prompting high numbers of problem-solving initiatives. But a substantial number of actions of the physicians following negative tests point to the risks of too aggressive treatment of elderly patients with possibly subsequent negative effects.
Insulating and Conducting Phases of RbC60
Michael C. Martin,Daniel Koller,Xiaoqun Du,Peter W. Stephens,Laszlo Mihaly
Physics , 1993, DOI: 10.1103/PhysRevB.49.10818
Abstract: Optical measurements were performed on thin films of Rb$_{x}$C$_{60}$, identified by X-ray diffraction as mostly $x=1$ material. The samples were subjected to various heat treatments, including quenching and slow cooling from 400K. The dramatic increase in the transmission of the quenched samples, and the relaxation towards the transmission observed in slow cooled samples provides direct evidence for the existence of a metastable insulating phase. Slow cooling results in a phase transition between two electrically conducting phases.
Infrared and Raman Evidence for Dimers and Polymers in Rb1C60
Michael C. Martin,Daniel Koller,A. Rosenberg,C. Kendziora,L. Mihaly
Physics , 1994, DOI: 10.1103/PhysRevB.51.3210
Abstract: The infrared- and Raman-active vibrational modes of C60 were measured in the various structural states of Rb1C60. According to earlier studies, Rb1C60 has an $fcc$ structure at temperatures above ~100C, a linear chain polymer orthorhombic structure when slowly cooled, and an as yet undetermined structure when very rapidly cooled ("quenched"). We show that the spectra obtained in the polymer state are consistent with each C60 molecule having bonds to two diametrically opposite neighbors. In the quenched state, we find evidence for further symmetry breaking, implying a lower symmetry structure than the polymer state. The spectroscopic data of the quenched phase are shown to be consistent with Rb2(C60)2, a dimerization of C60.
Energy gap in superconducting fullerides: optical and tunneling studies
Daniel Koller,Michael C. Martin,Laszlo Mihaly,Gyorgy Mihaly,Gabor Oszlanyi,Gabriel Baumgartner,Laszlo Forro
Physics , 1996, DOI: 10.1103/PhysRevLett.77.4082
Abstract: Tunneling and optical transmission studies have been performed on superconducting samples of Rb3C60. At temperatures much below the superconducting transition temperature Tc the energy gap is 2 Delta=5.2 +- 0.2meV, corresponding to 2 Delta/kB Tc = 4.2. The low temperature density of states, and the temperature dependence of the optical conductivity resembles the BCS behavior, although there is an enhanced ``normal state" contribution. The results indicate that this fulleride material is an s-wave superconductor, but the superconductivity cannot be described in the weak coupling limit.
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