Magnetotransport in a pseudomorphic GaAs/GaInAs/GaAlAs heterostructure with a Si delta-doping layer

Magnetotransport properties of a pseudomorphic GaAs/Ga0.8In0.2As/Ga0.75Al0.25As heterostructure are investigated in pulsed magnetic fields up to 50 T and at temperatures of T=1.4 K and 4.2 K. The structure studied consists of a Si delta-layer parallel to a Ga0.8In0.2As quantum well (QW). The dark electron density of the structure is n_e=1.67x 10^16 m^-2. By illumination the density can be increased up to a factor of 4; this way the second subband in the Ga0.8In0.2As QW can become populated as well as the Si delta-layer. The presence of electrons in the delta-layer results in drastic changes in the transport data, especially at magnetic fields beyond 30 T. The phenomena observed are interpreted as: 1) magnetic freeze-out of carriers in the delta-layer when a low density of electrons is present in the delta-layer, and 2) quantization of the electron motion in the two dimensional electron gases in both the Ga0.8In0.2As QW and the Si delta-layer in the case of high densities. These conclusions are corroborated by the numerical results of our theoretical model. We obtain a satisfactory agreement between model and experiment.Comment: 23 pages, RevTex, 11 Postscript figures (accepted for Phys. Rev. B

Quantitative determination of fluorescein in the anterior chamber and vitreous body

The blood-retinal barrier plays an important role in the physiology of the retina, the vitreous body and the aqueous humour. Many intra-ocular processes cause a breakdown of this barrier and this results in an increase in the concentration of fluorescein in the vitreous and the aqueous after it has been injected intravenously (Cunha-Vaz et al., 1975). In our clinic we have built an apparatus for the quantitative determination of the concentration of this fluorescein in both healthy and pathological eyes (Brubaker and Coakes, 1978). The goal of the present communication is to invite other workers with similar interests to compare their results with ours

Only Low Patients' Expectations Are Prognostic for Dissatisfaction With Performing Work-Related Knee-Straining Activities After Total Knee Arthroplasty:A Prospective Multicenter Cohort Study

OBJECTIVE: To investigate whether preoperative expectations regarding performing work-related knee-straining activities were associated with being dissatisfied 6 months after total knee arthroplasty (TKA) among working patients, and, to identify prognostic factors for being dissatisfied with performing these work-related knee-straining activities.DESIGN: Multicenter prospective cohort study.SETTING: Orthopedic surgery departments of 7 hospitals in the Netherlands.PARTICIPANTS: A consecutive sample of 175 working patients who were on the waiting list for TKA (median age 59 years, 53% women) and intended to return to work (N=175).INTERVENTIONS: Not applicable.MAIN OUTCOME MEASURE(S): Dissatisfaction with performing work-related knee-straining activities 6 months postoperative was measured using the Work Osteoarthritis or joint-Replacement Questionnaire (score range 0-100). The clinically relevant cut-off points for being satisfied and dissatisfied were ≥71 and ≤50, respectively.RESULTS: Thirty-three patients (19%) were dissatisfied with performing work-related knee-straining activities 6 months after TKA. Patients who expected to be dissatisfied preoperative had a 5.1 times higher odds (95% CI 1.7-15.5) of being dissatisfied 6 months postoperatively compared with patients who expected to be satisfied preoperative. Regression analyses revealed that only patients' expectations were prognostic for being dissatisfied 6 months postoperatively rather than age, pain level, or having a knee-straining job.CONCLUSIONS: Two in 10 working patients are dissatisfied with performing work-related knee-straining activities 6 months after TKA. Only preoperative patients' expectations appeared prognostic. Therefore, we should better prepare working patients with low expectations by managing their preoperative expectations and improving their performance of work-related knee-straining activities in rehabilitation.</p

Dutch influences on English literary culture in the early renaissance, 1470–1650

During the fifteenth, sixteenth and seventeenth centuries the Low Countries made a series of important contributions to English literature. Through such agents as the printers of Antwerp and Amsterdam, and the movements of Dutch scholars and Calvinist refugees, the Low Countries exerted a continuous impact on the literary culture of England. This article examines the scope of Dutch influence during the English Renaissance, indicates some of its key effects, and provides an overview of existing scholarship on the subject