Pflanzensoziologische Beobachtungen an isländischen Dünengesellschaften

Zusammenfassung Nachdem die Therophyten- und Hemikryptophyten-Spülsaum-Gesellschaften des Strandes geschildert worden sind, wird die Honckenya diffusa-Elymus arenarius-Ass. der isländischen Küste und der Flugsandflächen im Binnenlande beschrieben. Die weitere Entwicklung der Vegetation auf den Flugsand-Feldern führt zur Silene maritima-Festuca cryophila-Ass., die in verschiedenen Subassoziationen vorkommt.Die Wünschbarkeit einer Nachprüfung der örtlich gewonnenen Ergebnisse wird dargelegt und die pflanzensoziologische Kartierung eines ausgedehnten Flugsandgebietes beiderseits der Ölfusá-Mündung in SW-Island empfohlen.Die Festlegung des Flugsandes, die zur Sicherung der benachbarten Siedlungen notwendig ist, wird am sichersten, schnellsten und billigsten durch die Kenntnis und Beachtung der syndynamischen Gesetze der hier wachsenden Pflanzengesellschaften erreicht. Dabei sind Vegetation und Standort, d.h. die Flugsand-Dünen als eine lebendige Einheit im Sinne vonvan Dieren (1934) zu betrachten und die praktischen Erfahrungen an der deutschen und dänischen Nordsee-Küste von Wert, auf die verwiesen wird.Auf die Bedeutung der Kenntnisse von Soziologie, Syndynamik und Synökologie der s-isländischen Küsten-Vegetation für das Verständnis der Besiedlung der nahen jungen Vulkan-Insel Surtsey wird hingewiesen.     

Metabolic Studies and Clinical Observations During L-Dopa Treatment of Parkinson's Disease

Twenty-two patients with Parkinson''s disease were treated for the periods of up to six months with L-dopa. In nine of the male patients metabolic observations were made after oral administration of ¹⁴C-L-dopa.Peak serum levels of total radioactivity represented small fractions of the dose given and occurred at one to two hours after ingestion. Two-thirds of the dose was excreted as metabolites in urine in eight hours. Insignificant fractions of the dose were excreted in stool and expired air. These results indicate rapid and complete absorption from the gastrointestinal tract, as well as rapid distribution and excretion. Clinical observations confirmed that L-dopa is an effective treatment for Parkinson''s disease. Improvements in disability averaged 47% at 30 days, 55% at 50 days, and 60% at three months. Degree of improvement tended to be inversely related to age of patient, duration of illness, and severity of disease. Side-effects were seen in most patients, but were always reversible with dose reduction. Nausea was the chief dose-limiting side-effects in early therapy and choreoathetosis after two months of treatment. The average tolerated daily dose was 3 g. On the basis of this experience it seems that the drug can be used safely and effectively on an outpatient basis provided that dosage increments are introduced gradually, maximum dosage is limited to 4 g. a day, and supervision is both close and continuous.     

Synchronously dividing bacterial cultures. I. Synchrony following depletion and resupplementation of a required amino acid in Escerichia coli

Matney, Thomas S. (The University of Texas M. D. Anderson Hospital and Tumor Institute, Houston, Texas), and Joan C. Suit. Synchronously dividing bacterial cultures. I. Synchrony following depletion and resupplementation of a required amino acid in Escherichia coli. J. Bacteriol. 92:960-966. 1966.-A procedure was developed for phasing large-volume cultures of Escherichia coli K-12 with regard to cell division. The method consists of permitting the bacteria to exhaust a growth-limiting supply of a required amino acid, starving the culture, resupplementing with an excess of the amino acid, and following the ensuing growth by usual counting procedures.     

The parallactic view, statistical testing, and circular reasoning

A "parallactic view" (i.e., subjectivity in interpreting data) is an important and perhaps essential tool for formulating hypotheses, but it also represents a hazardous contaminant to be avoided in testing hypotheses. Computer simulations demonstrate that statistical testing of data that are contaminated by even a modest level of such parallax can be very misleading; probability levels are greatly distorted. An even more insidious influence of the parallactic view arises when the fundamental assumptions for a statistical test are not adequately respected. Single-cosinor analysis, which has been used to "demonstrate" circaseptan rhythms (tau = about 7 days), lends itself to such abuse: The statistical test of the zero-amplitude hypothesis assumes that if any serial correlation is present in the data, it is due to a sinusoidal oscillation with period that is known a priori. One cannot, therefore, legitimately use this method to demonstrate the existence of such a rhythm.