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  • Bone densitometry  (2)
  • 42.65  (1)
  • Abscisic acid  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 60 (1995), S. 437-442 
    ISSN: 1432-0649
    Keywords: 42.55 ; 42.65 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The design, configuration and operation of Ti:Sapphire-laser-pumped femtosecond Optical Parametric Oscillators (OPOs) using KTP and RTA are described. The results presented include configurations capable of producing transform-limited pulses shorter than 40 fs and operating with pump powers as low as 50 mW. Tunability within the 1–3 µn spectral region is demonstrated using pump-tuning alone.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-2965
    Keywords: Bone densitometry ; Broadband ultrasound attenuation ; Dual-energy X-ray absorptiometry ; Osteoporosis ; Perimenopausal women ; Screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper compares dual-energy X-ray absorptiometry (DXA) of the spine and hip and broadband ultrasound attenuation (BUA) of the os calcis in 1000 perimenopausal women aged between 45 and 49 years who attended a randomized Osteoporosis Screening Programme. Significant correlations were found between all DXA results and BUA, with the trochanter giving the best numerical correlation with BUA (r=0.354,p〈0.0001). BUA was not successful in predicting women with low DXA measurements, with only 44.0% of the women whose spinal DXA falls within the lowest quartile being in the lowest quartile of BUA. Although BUA is a poor predictor of spinal and hip bone mineral density it may provide additional structural information important in fracture prediction.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-2965
    Keywords: Aging ; Bone densitometry ; Epidemiology ; European Spine Phantom ; Geographic variation ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to investigate variations in bone density between 16 European populations, 13 of which were participants in the European Vertebral Osteoporosis Study (EVOS). Men and women aged 50–80 years were recruited randomly from local population registers, stratified in 5-year age bands. The other three centres recruited similarly. Random samples of 20–100% of EVOS subjects were invited for dual-energy X-ray absorptiometry (DXA) densitometry of the lumbar spine and/or proximal femur using Hologic, Lunar or Norland pencil beam machines or, in one centre, a Sopha fan-beam machine. Cross-calibration of the different machines was undertaken using the European Spine Phantom prototype (ESPp). Highly significant differences in mean bone density were demonstrated between centres, giving rise to between-centre SDs in bone density that were about a quarter of a population SD. These differences persisted when centres using Hologic machines and centres using Lunar machines were considered separately. The centres were ranked differently according to whether male or female subjects were being considered and according to site of measurement (L2–4, femoral neck or femoral trochanter). As expected, bone mineral density (BMD) had a curvilinear relationship with age, and apparent rates of decrease slowed as age advanced past 50 years in both sexes. In the spine, not only did male BMD usually appear to increase with age, but there was a highly significant difference between centres in the age effect in both sexes, suggesting a variability in the impact of osteoarthritis between centres. Weight was consistently positively associated with BMD, but the effects of height and armspan were less consistent. Logarithmic transformation was needed to normalize the regressions of BMD on the independent variates, and after transformation, all sites except the femoral neck in females showed significant increases in SD with age. Interestingly, the effect of increasing weight was to decrease dispersion in proximal femur measurements in both sexes, further accentuating the tendency in women for low body mass index to be associated with osteoporosis as defined by densitometry. It is concluded that there are major differences between BMD values in European population samples which, with variations in anthro-pometric variables, have the potential to contribute substantially to variations in rates of osteoporotic fracture risk in Europe.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5087
    Keywords: Abscisic acid ; cytokinins ; drought ; ethylene ; gibberellins ; sunflower ; water stress ; aeroponics ; roots ; shoots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Abscisic acid (ABA), cytokinins and gibberellin-like substances (GAs) were extracted from the roots and shoots of 17-day-old sunflower seedlings which had been droughted or were unstressed. Plants were grown in an aeroponic chamber which allowed for good control over degree of water stress and easy access to roots. Following methanolic extraction of lyophilized material, cytokinins were separated from the acidic growth-regulators on a cellulose PO4 cationic exchange column. The cytokinins were analysed by paper chromatography and HPLC and the soybean hypocotyl section assay. Semipurified acidic regulators were chromatographed on SiO2 columns and HPLC and aliquots assayed with the dwarf rice cv. Tan-ginbozu bioassay for GAs. Fractions known to contain ABA were purified by sequential reverse-phase HPLC of the acid and then of the methyl ester forms followed by quantitation as Me-ABA on GLC-EC. ABA losses were measured by using an internal standard [3H]-ABA). Ethylene production was also monitored in stressed and unstressed seedlings. The effect of drought on GAs and ethylene was minimal. The ABA levels were markedly higher in droughted plants. Stressed roots had 32 times more ABA than controls. The levels of cytokinins in the shoots of droughted plants were about half those in unstressed shoots, and qualitative differences occurred in the roots. Under stress a large peak of activity was present similar to zeatin glucoside which was not present in the unstressed condition. The results are discussed in relation to drought-effects on metabolism.
    Type of Medium: Electronic Resource
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