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  • 1
    ISSN: 1573-5117
    Keywords: boundary control ; Photogenesis control ; Nitella ; charophyte ; light regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two series of lakes with increasing attenuation were examined for trends in spectral composition. They became the basis for an evaluation of the light environment at the lower boundary (LB) of Nitella meadows in three other series of lakes. Increased attenuation (K d PAR) was marked by progressive erosion of the ‘blue window’ and caused primarily by humic substances. An increase in K d PAR from 0.06 to 0.81 produced, at the floor of the euphotic zone, a shift in K d min from 440 to 580 nm. Regressions of boundary depths of Nitella meadows on water clarity produced similar slope coefficients for the three series of lakes. Several trends became evident: 1, PAR irradiance at the LB increases with depth of the LB; 2, red light (E d 660) declines from richness at shallow LB to near extinction in deep water LB in clear lakes; while 3, blue light (K d 450) increases to an asymptote. Blue light appears to substitute, although less effectively, for red light irradiance in the growth regulation of charophytes. These data support an hypothesis that spectral quality is involved in the determination of lower boundary depths for benthic macro-algae.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 383 (1998), S. 485-491 
    ISSN: 1435-2451
    Keywords: Key words Gastric carcinoma ; Total gastrectomy ; Duodenal passage ; Pouch reconstruction ; Quality of life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: More than 60 different methods of reconstruction after total gastrectomy have been described. The different surgical procedures can be reduced essentially to pouch reconstruction, pouch size and maintenance of duodenal passage. Methods: To clarify the importance of pouch reconstruction and maintenance of duodenal passage, we reviewed all controlled prospectively randomized clinical studies reporting on the various methods of reconstruction after gastrectomy. Results: After reconstruction with a pouch, 6-month postoperative patients have a better food intake, a slower food passage (t50% 12 vs 25 min), fewer postprandial symptoms (4–10% vs 20–60%), less weight loss (7 vs 14kg), and in tendency, they have a better quality of life. With maintenance of duodenal passage, disturbance of blood sugar regulation (stimulated glucose level 22% lower) and iron deficiency anemia (hemoglobin: 13.9 vs 12.5 g/dl; iron: 18.4 vs 10.2 μmol/l) are prevented. In addition, the patients lose less body weight (8% higher) and they tend to have a better quality of life (life quality score: 84 vs 76 points). Nevertheless, in several studies the number of patients is too small to demonstrate significant differences. Conclusions: After total gastrectomy, curatively operated patients might benefit from a reconstruction with pouch and maintenance of duodenal passage. Nevertheless, the present study results are partially divergent. For definitive demonstration of the superiority of this technique, further controlled longitudinal studies should be conducted with a larger number of cases and suitable instruments for assessing the quality of life.
    Type of Medium: Electronic Resource
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