Survival of bacteriophages in seawater

The stability of T₂ bacteriophage in seawater was investigated under laboratory conditions and in the natural waters of a bay. Inactivation was temperature dependent and was enhanced by sunlight and sewage pollution. Chemical inactivation did not appear to be a major factor.     

The role of the gas phase in the greening and growth of illuminated cell suspension cultures of spinach (Spinacia oleracea, L.)

The gas phase developed above spinach suspension cultures critically affected their growth and greening. Ethylene accumulation inhibited greening; this effect of ethylene was antagonised when the culture gas phase was enriched with carbon dioxide. Greening was enhanced by reducing the partial pressure of oxygen below the air level; this effect was observed when oxygen supply did not restrict growth.     

Thermal Mass and Thermal Inertia in Fluids — A Comparison of Hypotheses

Thermal inertia and thermal mass are concepts that offer means to describe transport of heat in nonequilibrium fluids. However there are options regarding how to separate the part of the total flow that caries entropy from the "mechanical", nonentropy-bearing part. Some hypotheses are examined and compared for constructing such a field theory of thermal mass in the energy representation. A global intrinsic symmetry and a finite thermal momentum imply that any formulation which hypothesizes a constant ratio of thermal mass to the entropy must tie the thermal mass to the so-called bare mass of particles, to preserve the global conservation of matter. However, in any formulation consistent with the Grad-Boltzmann theory, where must be variable, the thermal mass behaves as a separate variable governed by the entropy and the second law. Nonetheless, in this case has a reasonably broad plateau of values within which entropy is a measure of the thermal mass associated with changes of state. Nonlinear transformations linking usual thermodynamic variables with those of the thermal mass frame preserve the components of the tensor of matter, including Nöther's energy and pressure. A formula is given for the fraction of the observed mass assignable as thermal mass, in accordance with Grad's solution of the Boltzmann equation.     

Language design methods based on semantic principles: Algol 68, a Language Designed using Semantic Principles

Summary This note observes that Tennent's proposed language design method is that used by Algol 68's designers and points out how his proposed extensions to Pascal bring it closer to Algol 68. Some implications of his proposal are discussed.On Sabbatical from: Computer Science Department, University of California, Los Angeles, Los Angeles, CA 90024, USA     

Oxidative damage of retinal rod outer segment membranes and the role of vitamin E

Highly purified bovine rod outer segment membranes show loss of structural integrity under an air atmosphere. Obvious ultrastructural changes are preceded by increases in absorbance below 400 nm. These changes are inhibited by Ar or N2 atmospheres and appear to be due primarily to oxidative damage to the polyunsaturated fatty acids of the membrane lipids. Loss of polyunsaturated fatty acids, formation of malonaldehyde and fluorescent products characteristic of lipid oxidation accompany the spectral alterations. The elevated ultraviolet absorbance can largely be removed from the membranes by gentle extraction of the lipids using phospholipase C and hexane without changing the visible absorbance of rhodopsin. We have found a large seasonal variation in the endogenous level of alpha-tocopherol (vitamin E) in the bovine rod outer segment preparations. For much of the year we find that the rod outer segment membranes contain higher levels of alpha-tocopherol than have been previously reported in biological membranes. Rod outer segments which are low in endogenous tocopherol can be protected from oxygen damage by adding exogenous tocopherol. The rod outer segments are extremely susceptible to oxygen damage due to the unusually high content of polyunsaturated fatty acids in the membrane lipids. The presence of tocopherol inhibits oxygen damage but does not eliminate it. The tocopherol in the rod outer segments is consumed in air, thus complete protection from peroxidation in vitro requires an inert atmosphere as well as high levels of tocopherol. This work suggests that extensive precautions against oxidative degradation should also be employed in studies of other membrane systems where important deleterious effects of oxygen may be less obvious.     

Determination of power absorption in man exposed to high frequency electromagnetic fields by thermographic measurements on scale models

Ultrafiltrable serum uric acid (u.a.) was determined by ultrafiltration under in vivo conditions in humans using a reliable technique described in detail. It could be demonstrated that u.a. binding to macromolecules occurs in healthy humans (controls) and in patients with renal calcium stones. The percentage of free u.a. in controls (n=60) averages 86.2 +/- 0.9 SEM. With increasing age, bound u.a. rises slightly. On the other hand, younger (less than 40 years) stone patients have significantly more bound u.a. than matched controls (80.7 +/- 1.0 SEM; p less than 0.001), whereas this is not found in elderly patients. The degree of binding is not related to concentration of plasma proteins but inversely related to free fatty acid concentration in healthy controls (r= -0.52; p less than 0.01). It is suggested that no augmentation of tubular u.a. filtered by the glomeruli could have occurred. The origin of fasting hyperuricosuria shown earlier to be a prominent feature of young renal calcium stone formers is yet unknown.