Das Verhalten des Quotienten Harnstoff-N:Rest-N bei normalen und nephrektomierten,urämischen Ratten

Summary (1) The quotient urea nitrogen: non-protein nitrogen was determined in nephrectomized uremic rats and compared with the quotient in control animals. The quotient in nephrectomized uremic animals was 0.74, in control animals 0.35. The elevation of the quotient is of hepatic origin.(2) The desamination was increased in the liver of nephrectomized uremic animals in comparison to controls; the urea production was unchanged.     

Über die hemmung des wachstums vonLactobacillus casei durch einige antiphlogistica

Summary A new method for the classification of antiphlogistics is described using the growth inhibition ofLactobacillus casei. In this test the fenamic acids and particularly the new class of the Cinnopentazon-antiphologistics (Scha 306, Scha 764 etc.) exhibit bacteriostatic properties of a medium intensity.

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Alexander von Muralt zum 65. Geburtstag gewidmet.     

Optical frequency metrology

Extremely narrow optical resonances in cold atoms or single trapped ions can be measured with high resolution. A laser locked to such a narrow optical resonance could serve as a highly stable oscillator for an all-optical atomic clock. However, until recently there was no reliable clockwork mechanism that could count optical frequencies of hundreds of terahertz. Techniques using femtosecond-laser frequency combs, developed within the past few years, have solved this problem. The ability to count optical oscillations of more than 1015 cycles per second facilitates high-precision optical spectroscopy, and has led to the construction of an all-optical atomic clock that is expected eventually to outperform today's state-of-the-art caesium clocks.     

The unusual γ-ray burst GRB 101225A from a helium star/neutron star merger at redshift 0.33

Long γ-ray bursts (GRBs) are the most dramatic examples of massive stellar deaths, often associated with supernovae. They release ultra-relativistic jets, which produce non-thermal emission through synchrotron radiation as they interact with the surrounding medium. Here we report observations of the unusual GRB 101225A. Its γ-ray emission was exceptionally long-lived and was followed by a bright X-ray transient with a hot thermal component and an unusual optical counterpart. During the first 10 days, the optical emission evolved as an expanding, cooling black body, after which an additional component, consistent with a faint supernova, emerged. We estimate its redshift to be z = 0.33 by fitting the spectral-energy distribution and light curve of the optical emission with a GRB-supernova template. Deep optical observations may have revealed a faint, unresolved host galaxy. Our proposed progenitor is a merger of a helium star with a neutron star that underwent a common envelope phase, expelling its hydrogen envelope. The resulting explosion created a GRB-like jet which became thermalized by interacting with the dense, previously ejected material, thus creating the observed black body, until finally the emission from the supernova dominated. An alternative explanation is a minor body falling onto a neutron star in the Galaxy.     

Enzymes of arginine biosynthesis in methanogenic bacteria

Summary Methanobacterium thermoautotrophicum, Methanococcus vannielii andMethanobrevibacter arboriphilus, the 3 methanogenic bacteria tested, possessed an ornithine acetyltransferase and an arginine-sensitiveN-acetylglutamate 5-phopshtransferase. These 2 enzymes, as well as acetylornithinase and ornithine carbamoyltransferase, were insensitive to oxygen and were present at activity levels comparable to the levels observed in eubacteria.Acknowledgments. This work was supported by the Swiss National Foundation for Scientific Research (project No. 3.287.82). We thank A. Kiener for valuable discussions.     

Reciprocal autoregulation of blood flow and blood pressure

Zusammenfassung Der Eingangswiderstand verschiedener Arterien wurde im Niederfrequenzbereich (0,0005 bis 0,25 Hz) mittels sinusförmig modulierter Pumpen-Perfusion mit arteriellem Blut an narkotisierten Hunden gemessen. Die Resultate lassen die Existenz zweier reziprok wirkender Autoregulationsmechanismen vermuten, deren Frequenzcharakteristik mit Hilfe eines einfachen linearen Modells simuliert werden konnte.

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Supported by NIH Grant No. HE 11747.