Showing papers in "Biophysical Journal in 1961"

TL;DR: Van der Pol's equation for a relaxation oscillator is generalized by the addition of terms to produce a pair of non-linear differential equations with either a stable singular point or a limit cycle, which qualitatively resembles Bonhoeffer's theoretical model for the iron wire model of nerve.

TL;DR: It was concluded that gaseous equilibration may be considerably accelerated by bolus flow, though this may be more of a limiting factor in peripheral capillaries than in the pulmonary circulation.

TL;DR: Salmon DNA has been irradiated with visible light in the presence of acridine orange and CsCl banding experiments show that the first two effects reflect depolymerization of the DNA.

TL;DR: The effect of slice thickness was investigated by a mathematical procedure involving the solutions of approximate differential equations and it was shown that even for slices so thick that 95 per cent of the solute in the gel is contained in the first two, a correction factor equal to the square of the slice thickness divided by 48D't permits one to obtain accurate measurement of D' from the mean concentration and the position of the midplane of theslice.

TL;DR: In this paper, the distribution of labeled DNA, RNA, protein, and cell wall among the progeny cells of successive generations was examined by quantitative radioautographic techniques, and it was found that DNA is in large structures, non-randomly distributed in the progeni.

TL;DR: The survival of yeast cells after exposure to subzero temperatures was affected by the cooling and warming velocity, temperature itself, and the physical state of the water surrounding the cells, indicating that death is a result of intracellular ice formation.

TL;DR: Results are consistent with the hypothesis that the enzyme-forming unit is unstable and the steady-state rate of β-galactosidase synthesis is approximated by I2/I2 + K2.

TL;DR: In this article, the characteristics of a certain class of two terminal dissipative elements and the conditions under which such elements will display both real and imaginary components of AC impedance are specified.

TL;DR: By using complex inputs the predictive apparatus is eliminated and steady state experiments can be used to study the neurological response and a series of linearity and other control experiments elucidate the limitations and adequacies of the method.

TL;DR: The integral sedimentation distributions of these preparations suggest a high degree of homogeneity among the molecules of each of the three classes, which seems to result from sequential breaks in the molecules since the proportion of smaller molecules increases with time of treatment.

TL;DR: The hypothesis is considered that replication and selection began from well ordered sequences, rather than random sequences, and Macromolecular models of such computers are suggested on the basis of mechanisms proposed for the growth of eutactic polymers.

TL;DR: The experimental data indicated that the graded receptor potential does not arise solely from a collapse of the resting membrane potential of the sensory cells of the eye, since a reversal of polarity of the photoreceptor unit could be demonstrated when the eye was stimulated by light.

TL;DR: Small-angle x-ray scattering studies on an absolute scale have been carried out on isotropic solutions of high molecular weight RNA obtained from ascites tumor cells, E. coli, and yeast, and it was found that in all three cases the RNA is composed of short rigid rods joined by small flexible regions.

TL;DR: The studies indicate boundary conditions to include the following: A 189 A identity period, with a pseudoidentity of 94.5 A, and the possibility of breaking down the structure into units of about 10,000 molecular weight.

TL;DR: Four types of ribosomes occurring in E. coli have been separated by sucrose gradient centrifugation, and Native and derived 30S particles were found to contain 16S RNA, whereas derived 50S particles contained 23S RNA and a small amount of 15 to 20S RNA.

TL;DR: Preliminary results indicate that the assumption that the proline residues in feather keratin are periodically located along the polypeptide chain is better capable of accounting for the data than previously proposed structures.

TL;DR: Algae tested appear to contain approximately 3 to 5 per cent of their chlorophyll as Ca695; this proportion does not increase as strikingly with lowering of the light intensity as it does in Euglena, but cells containing a large proportion of Ca695 have a fluorescence maximum at 708 mμ, as contrasted to the 687 mμ maximum in other algae.

TL;DR: The kinetics of degradation of DNA by deoxyribonuclease II have been studied, using the techniques of light scattering, viscosity, and titration, and it has been shown that these equations permit a valid calculation of the number of polynucleotide strands per molecule.

TL;DR: It is shown that the single substrate 5'-adenylic acid (AMP) of deaminase "protects" the enzyme against antibody inhibition, however, phosphate, a competitive inhibitor of the highly specific deamin enzyme, enhances combination with antibody.

TL;DR: The theory of the electromagnetic blood flow measuring technique is extended from the well known case (conductive liquid flowing through an insulating tube) to more realistic situations and the evidence is established that flowmeter cuffs should fit the blood vessels accurately to minimize errors.

TL;DR: X-ray scattering data are presented on solutions of wild cucumber mosaic virus and the associated "top component" particles which have little or no RNA.

TL;DR: The relationship between the molecular units produced by cesium chloride treatment and the units conserved during DNA replication is discussed.

TL;DR: It is shown that the "second Emerson effect" exists not only in photosynthesis, but also in the quinone reduction (Hill reaction), in Chlorella pyrenoidosa and Anacystis nidulans, and the participation of phycocyanin in the Emerson effect in the Hill reaction is revealed.

TL;DR: The kinetics of the synthesis of ribosomal RNA in E. coli has been studied using C(14)-uracil as tracer to indicate that ribosome synthesis occurs by concurrent conversion of small to large molecules of RNA and small to small ribosomes.

TL;DR: The replication cycle of the DNA molecule has been shown to consist of an alternation between the four- and two-stranded forms, the latter being the conserved unit.

TL;DR: It was found that shaking with chloroform-octanol does not degrade DNA from the seven sources studied; that light scattering yields valid weight-average molecular weights for these samples; and that, when disaggregated, the molecular weights of these samples are in the range 1.2-2.4 million and the length-to-mass ratios are high.

TL;DR: A kinetic model for a two pigment mechanism of photosynthesis based on observations made on the red alga Porphyridium cruentum showed the Emerson enhancement effect, chromatic transients, "respiratory stimulation," and other effects observed with live algae.

TL;DR: A method which was derived in a previous paper for calculating the energy expended in an active transport system has been generalized to a linked transport system, multiple pathways, and electrically non-neutral particles.

TL;DR: The inhibition of macromolecular synthesis in Escherichia coli by ionizing radiation has been investigated and the long thin character observed for amino acids suggests that the sensitive region affected by radiation is an unfolded form of a ribosome, or alternatively a long nucleic acid molecule.

TL;DR: A sequence of reactions is postulated from which are derived equations describing the time course of enzyme induction and the observed effect of the inducer concentration on the time constant and final rate of enzyme synthesis.