Biomedical subjects

A Erb

Publications and source records attributed to A Erb.

At least 19 recordsLinked to original sources

PubMed2006

Effect of Zn and Ni impurities on the quasiparticle renormalization of superconducting Bi-2212.

The Cu substitution by Zn and Ni impurities and its influence on the mass renormalization effects in angle-resolved photoelectron spectra (ARPES) of Bi2Sr2CaCu2O8-delta is addressed. We show that the nonmagnetic Zn atoms have a much stronger effect in both the nodal and antinodal parts of the Brillouin zone than magnetic Ni. The observed changes are consistent with the behavior of the spin resonance mode as seen by inelastic neutron scattering in YBCO. This strongly suggests that the "peak-dip-hump" and the kink in ARPES on the one side and neutron resonance on the other are closely related features.

Journal Article↗

PubMed2004

Triangular to square flux lattice phase transition in YBa2Cu3O7.

We have used the technique of small-angle neutron scattering to observe magnetic flux lines directly in a YBa2Cu3O7 single crystal at fields higher than previously reported. For field directions close to perpendicular to the CuO2 planes, we find that the flux lattice structure changes smoothly from a distorted triangular coordination to nearly perfectly square as the magnetic induction approaches 11 T. The orientation of the square flux lattice is as expected from recent d-wave theories but is 45 degrees from that recently observed in La(1.83)Sr(0.17)CuO(4+delta).

Journal Article↗

PubMed2004

Prevalence and determinants of nasal colonization with antibiotic-resistant Staphylococcus aureus among unselected patients attending general practitioners in Germany.

Although the great majority of antibiotics are prescribed outside hospitals, little is known about the prevalence and determinants of antibiotic resistance in the group of outpatients. Nasal swabs were taken from 627 consecutive patients aged 40 years or above attending general practitioners in Southern Germany. Staphylococcus aureus was cultured and minimal inhibitory concentrations to various antibiotics were tested. Nasal swabs of 152 patients were positive for S. aureus. Prevalence of resistance was 68.3, 8.3 and 0.7% for penicillin G, erythromycin, and oxacillin respectively. Antibiotic use within the last month was associated with erythromycin resistance [adjusted odds ratio (OR) 7.4; 95 % confidence interval (CI) 1.0-53]. Besides a high prevalence of resistance to penicillinase-instable antibiotics we found only one (0.7%) methicillin-resistant S. aureus. Recent antibiotic use was associated with increased resistance to erythromycin.

Adult↗

PubMed2002

Oxygen isotope effect in the ab-plane reflectance of underdoped YBa(2)Cu(3)O(7-delta).

We have measured the effect of oxygen isotope substitution on the ab-plane reflectance of underdoped YBa(2)Cu(3)O(7-delta). The frequency shift of the transverse optic phonons due to the substitution of 16O by 18O yields an isotope effect of the expected magnitude for copper-oxygen stretching modes with alpha=0.5+/-0.1. The reflectance shoulder at 400-500 cm(-1) shows a much smaller exponent of alpha=0.1+/-0.1 in the normal state and alpha=0.23+/-0.1 in the superconducting state. These observations suggest that the shoulder is of electronic origin and not due to a phonon mode as has been suggested recently.

Journal Article↗

PubMed2001

Determinants of impaired renal function with use of nonsteroidal anti-inflammatory drugs: the importance of half-life and other medications.

PURPOSE: Nonsteroidal anti-inflammatory drugs (NSAIDs) may interfere with renal function, but little is known about the effects of the half-life of these agents, or the use of other medications, on renal function. SUBJECTS AND METHODS: Medication use was assessed during a standardized interview in a cross-sectional study of 802 patients undergoing total joint replacement because of osteoarthritis. Preoperative blood samples were used to estimate creatinine clearance using a standard formula that takes age, sex, and weight into account. Impaired renal function was defined as an estimated creatinine clearance less than 60 mL/min (fifteenth percentile). Multivariable logistic regression was used to estimate the adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association between NSAID use (alone or in combination with diuretics or angiotensin-converting enzyme [ACE] inhibitors) and impaired renal function. RESULTS: NSAID use per se was only marginally associated with impaired renal function (OR = 1.4; 95% CI, 0.9 to 2.2). This association was almost exclusively the result of the use of NSAIDs with a half-life of 4 or more hours (OR = 2.6; 95% CI: 1.2 to 5.7). Patients who used diuretics with NSAIDs (OR = 3.7; 95% CI: 1.7 to 8.3) or without NSAIDs (OR = 3.5; 95% CI: 1.6 to 7.6) had a higher risk of impaired renal function than did patients using NSAIDs alone (OR = 1.6) or none of these drugs (reference). A similar but less pronounced pattern was observed for ACE inhibitors. CONCLUSION: NSAID-associated impaired renal function seems to be mainly the result of compounds with intermediate-long half-life. We found no evidence that the adverse effects of diuretics and ACE inhibitors on renal function were greater in those who also used NSAIDs.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

Observation of out-of-phase bilayer plasmons in YBa(2)Cu(3)O(7-delta)

The temperature dependence of the c-axis optical conductivity sigma(omega) of optimally and overdoped YBa2Cu3Ox ( x = 6.93 and 7) is reported in the far- (FIR) and midinfrared (MIR) range. Below T(c) we observe a transfer of spectral weight from the FIR not only to the condensate at omega = 0, but also to a new peak in the MIR. This peak is naturally explained as a transverse out-of-phase bilayer plasmon by a model for sigma(omega) which takes the layered crystal structure into account. With decreasing doping the plasmon shifts to lower frequencies and can be identified with the surprising and so far not understood FIR feature reported in underdoped bilayer cuprates.

Journal Article↗

PubMed2000

Hormone replacement therapy and patterns of osteoarthritis: baseline data from the Ulm Osteoarthritis Study.

OBJECTIVES: It has been suggested that hormone replacement therapy (HRT) may protect against osteoarthritis (OA). The aim of this paper was to assess the association between HRT and radiographically defined patterns of OA. METHODS: 475 consecutive women aged 50 years or older (mean age 66.1) who underwent hip or knee joint replacement because of advanced OA in four hospitals in south west Germany were enrolled in a cross sectional study. Participants underwent a standardised interview including detailed history of medication use and a physical examination. Furthermore, radiographs of the joint being replaced and of the contralateral joint as well as of both hands were obtained. Patients were categorised as having bilateral or unilateral OA according to the presence or absence of radiographic OA in the contralateral joint. If radiographic OA of different hand and finger joint groups was present, participants were categorised as having generalised OA (GOA). Logistic regression was used to estimate odds ratios and their 95% confidence intervals for the association between HRT and bilateral or GOA while adjusting for potential confounders. RESULTS: Fifty five women (11.6%) were using HRT. The median duration of use was 5.4 years. The prevalence of bilateral and GOA was similar among users of ORT (86.3% and 27.5%, respectively) and among non-users of HRT (88.7% and 35.7%, respectively). After adjustment for potential confounding factors, the odds ratios (95% confidence intervals) of bilateral OA and GOA among HRT users compared with non-users was 1.21 (0.48, 3.03) and 1. 21 (0.53, 2.74), respectively. CONCLUSION: Despite limited generalisability because of the selective study sample, these data do not support the hypothesis that HRT acts as a systemic protective factor against OA.

Aged↗

PubMed1995