Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles: DFG German National Licenses  (6)
  • 2000-2004  (4)
  • 1990-1994  (2)
  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A nondestructive method is presented which allows a precise detection of defects and their positions inside the cavity of semiconductor lasers. The defect recognition is based on the measurement of the longitudinal mode spectrum below threshold and the inspection of its Fourier transformation. Using a theoretical model, it is shown that a small distortion inside the cavity leads to a peak in the Fourier transformed spectrum from which the position of the distortion relative to the facets can be determined. For a ridge waveguide laser we find a direct correlation between defects identified by the analysis of the longitudinal mode spectrum and cathodoluminescence imaging. The applicability of this method for nondestructive defect recognition will also be demonstrated for broad area laser diodes with lateral multimode emission. The investigations reveal that the presented method can be used to assess the crystal quality of manufactured laser diodes. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1965-1967 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Highly strained InGaAs quantum wells were grown by metalorganic vapor-phase epitaxy. By lowering the growth temperature to 530 °C, a maximum photoluminescence wavelength of 1192 nm was achieved. High-power diode lasers with a maximum lasing wavelength of 1175 nm were fabricated. A continuous-wave output power of 12 W at a heat-sink temperature of 25 °C was obtained at a lasing wavelength of 1120 nm. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2653-2655 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The threshold current and the external efficiency of a three-section distributed Bragg reflector laser are investigated as a function of a forward electrical bias applied to the passive sections. Within a well-determined range, the threshold current increases and the external efficiency decreases with increasing bias. This effect is attributed to band gap renormalization. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-0428
    Keywords: Keywords Switzerland, diabetes, cost-effectiveness, intensive therapy, screening, microalbuminuria, renal failure, blindness, disease modelling.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. A computer model was developed to determine the health outcomes and economic consequences of different combinations of diabetes interventions in newly diagnosed patients with Type I (insulin-dependent) diabetes in Switzerland.¶Methods. We modelled seven complications of diabetes: hypoglycaemia, ketoacidosis, acute myocardial infarction, stroke, lower extremity amputation, nephropathy, and retinopathy. Transition probabilities and costs were taken from published literature. The Swiss health insurance payer perspective was taken. Various combinations of diabetes management strategies, including intensive or conventional insulin therapy and screening and treatment strategies for renal and eye disease were defined. Life expectancy, cumulative incidences of complications, and mean expected total lifetime costs per patient were calculated under six different management strategies. Incremental cost-effectiveness ratios were calculated in terms of costs per life-year gained compared with conventional insulin therapy alone.¶Results. The addition of screening for microalbuminuria and retinopathy followed by appropriate treatment, if detected, were cost saving, with reduction in cumulative incidence of end stage renal disease and blindness respectively, and, in the case of microalbuminuria screening and treatment, an improvement in life expectancy. Intensive therapy improved life expectancy but increased total lifetime costs.¶Conclusion/interpretation. Optimal management of Type I diabetic patients, including secondary and tertiary prevention, leads to reduced complications and improved life expectancy, with the increased costs of prevention offset to varying degrees by cost savings due to complications avoided. [Diabetologia (2000) 43: 13–26]
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 61 (1990), S. 101-103 
    ISSN: 1432-1246
    Keywords: Energy expenditure ; Douglas Bag ; Kofranyi-Michaelis respirometer ; Oxylog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to determine energy expenditure, the Douglas Bag technique (DB) and Kofranyi-Michaelis respirometers (KM) have been widely used under field conditions for several decades. Some years ago the Oxylog (OX) method was developed, measuring simultaneously the difference of partial oxygen pressure in inspired and expired air (PO2 diff.) by two polarographic oxygen sensors. In order to compare these three methods laboratory experiments (3 test subjects, 5 different bicycle ergometer work loads, 180 measurements per apparatus) were performed. Oxygen uptake (VO2) varied between about 0.9 to 3.01/min. The VO2data obtained by the DB method, which were used as a reference, and those obtained by the KM method agreed fairly well. The recorded data of OX underestimated VO2up to 21%, with the deviation increasing with work intensity. A sufficient accuracy of recorded VO2 was observed only up to moderate work intensity. OX data calculated from ventilation volume of inspired air per minute (V1) and PO2 diff., measured by OX, were always about 19% higher than those recorded by OX. This means that the calculated VO2 values of the OX corresponded fairly well with DB values at heavy work loads. The reason for the differences between recorded and calculated OX data is still unknown. Further research is urgently needed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 61 (1990), S. 380-385 
    ISSN: 1439-6327
    Keywords: Calibration ; Tissot spirometer ; Kofranyi-Michaelis respirometer ; Wet gasmeter ; Oxylog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Various methods for determinating energy expenditure by indirect calorimetry are used in laboratory and field studies such as the Douglas bag method, often used in combination with a wet gasmeter, the respirometer of Kofranyi and Michaelis (KM) and the Oxylog (OX). To calibrate the volume measurements of these pieces of apparatus a modified Tissot spirometer was built, consisting of an outer casing filled with water, a core and a bell. It was equipped with a solid counterbalance and with an additional roller chain, partly freely suspended on the side of the counterbalance. This construction allowed compensation for the varying buoyancies of the bell. The lift of the bell was measured by means of a vernier scale. From calculations of the geometric volume a revolution counter was adapted to record the moved volume in litres. By means of this spirometer volumes up to 2001 can be used for calibration at various physiological flow rates. Calibration procedures for KM, wet gasmeters and OX were developed. For OX a small inaccuracy up to 2.0% was observed within the flow range from 20 to 701·min−1. The inaccuracy increased at higher flow rates. Under defined calibration conditions the modified Tissot spirometer enabled repeated calibrations of different types of gasmeters.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...