Showing papers by "University of California published in 1975"
TL;DR: Much of what constitutes the core of scientific knowledge may be regarded as a reservoir of concepts and techniques which can be drawn upon to construct mathematical models of various types of systems and thereby yield quantitative information concerning their behavior.
12,530 citations
TL;DR: In this article, the Whitney sum of three (Tf t )-invariant continuous subbundles of a Riemann manifold is used to define hyperbolic tangent bundles.
Abstract: Let M be a compact (Riemann) manifold and (f t ): M → M a differentiable flow A closed (f t )-invariant set ∧ ⊂ M containing no fixed points is hyperbolic if the tangent bundle restricted to ∧ can be written as the Whitney sum of three (Tf t )-invariant continuous subbundles
$${T_\Lambda }M = E + {E^s} + {E^u}$$
where E is the one-dimensional bundle tangent to the flow, and there are constants c λ>0 so that
$$(a)||T{f^t}(v)||\underset{\raise03em\hbox{$\smash{\scriptscriptstyle-}$}}{ \leqslant } c{e^{ - \lambda t}}||v||forv \in {E^s},t\underset{\raise03em\hbox{$\smash{\scriptscriptstyle-}$}}{ \geqslant } 0and$$
$$(b)||T{f^{ - 1}}(v)||\underset{\raise03em\hbox{$\smash{\scriptscriptstyle-}$}}{ \leqslant } c{e^{ - \lambda t}}||v||forv \in {E^u},t\underset{\raise03em\hbox{$\smash{\scriptscriptstyle-}$}}{ \geqslant } 0$$
727 citations
01 Jan 1975
TL;DR: In this article, the relation between nonequilibrium statistical mechanics and ergodic theory has been studied, and a notation for discussing finite systems of classical point particles has been established.
Abstract: We begin with some very general and elementary remarks about nonequilibrium statistical mechanics. We then establish our notation for discussing finite systems of classical point particles, construct the microcanonical ensemble, and sketch some of the relations between statistical mechanics and ergodic theory.
626 citations
TL;DR: Identification of mutant variants of the sequence combined with the in vitro biochemical studies of others has allowed us to tentatively identify the recognition site for each of these proteins, and to suggest how CAP might act at a distance to affect the interaction of RNA polymerase with the promoter.
Abstract: The nucleotide sequence of the lac promoter-operator region has been determined. The 122 base pairs comprising this region include the recognition sites for RNA polymerase, the positive regulatory protein, CAP, and the negative regulatory protein, the repressor. Identification of mutant variants of the sequence combined with the in vitro biochemical studies of others has allowed us to tentatively identify the recognition site for each of these proteins, and to suggest how CAP might act at a distance to affect the interaction of RNA polymerase with the promoter.
480 citations
TL;DR: This paper argued that Rawls's attempt to suggest a viable alternative to utilitarianism does not succeed, and argued that A Theory of Justice is the only ethical theory proposing a reasonably clear, systematic, and purportedly rational concept of morality.
Abstract: John Rawls’s A Theory of Justice 1 is an important book. It is an attempt to develop a viable alternative to utilitarianism, which up to now in its various forms was virtually the only ethical theory proposing a reasonably clear, systematic, and purportedly rational concept of morality. I shall argue that Rawls’s attempt to suggest a viable alternative to utilitarianism does not succeed. Nevertheless, beyond any doubt, his book is a significant contribution to the ongoing debate on the nature of rational morality.
383 citations
TL;DR: In Winfree's terminology, the existence of isochrons is shown and some of their properties are established and the models leading to these questions concerning dynamical systems are discussed.
Abstract: Winfree has developed mathematical models for his phase resetting experiments on biological clocks. These models lead him to ask a number of mathematical questions concerning dynamical systems. This paper deals with these mathematical questions. In Winfree's terminology we show the existence of isochrons and establish some of their properties.
364 citations
01 Jan 1975
TL;DR: In this article, the average asymptotic behavior of orbits of points in the neighborhood U of a C2-attractor is studied. But the main result is not related to our work.
Abstract: where E is the one-dimensional bundle tangent to the flow, and there are constants c, 2 > 0 so that (a) IlTf'(v)ll =O and (b) IlZf-'(v)lI O. We can choose t o > 0 and change 2 so that the above conditions hold with c = 1 when t > t o. We can also assume that, for such t, T f t (resp. Tf -t) expands E at a smaller rate than it expands any element of E u (resp. E~). It is then said that the metric is adapted (see [-14]) to f,o. We will always assume that t o < l t h i s can be achieved by a rescaling of t (t-~ t' = t/to) which does not affect our main results. A closed invariant set A is a basic hyperbolic set if (a) A contains no fixed points and is hyperbolic; (b) the periodic orbits of f~lA are dense in A; (c) f t lA is a topologically transitive flow; and (d) there is an open set U ~ A with A = ~ f~ U. tE~ These sets are the building blocks of the Axiom A flows of Smale [27]. We will especially be interested in attractors, basic hyperbolic sets A for which the U in (d) can be found satisfying f f U c U for all t > T O (T O fixed) and hence A = N f ' U. t>__0 This paper will study the average asymptotic behavior of orbits of points in the neighborhood U of a C2-attractor. Precisely we will find an ergodic probabili ty m e a s u r e / ~ on a C 2 attractor A so that for almost all x e U w.r.t. Lebesgue measure and all continuous g: U ~ R one has T lim 1 ! g ( f f x) d t = S g d ~ (1) T~ot~ T
258 citations
TL;DR: It is now apparent that steroids induce de novo synthesis of both messenger RNA (mRNA) and ribosomal RNA (rRNA); the role of the former in directing the synthesis of specific proteins is reasonably clear but that of the latter remains to be elucidated.
202 citations
TL;DR: In this article, a short and eclectic review of lipoproteins and their role in transport of non-polar lipids is presented, with a focus on the role of apoprotein proteins.
Abstract: Lipids are transported in blood plasma in association with proteins. Some polar lipids are transported by albumin (free fatty acids, bile acids) or by specific binding proteins (retinol-binding protein). Nonpolar lipids are transported in large complexes containing polar lipids and specific apoproteins (which serve functions beyond that of “packaged”). These complexes comprise the macromolecular particles that we generally think of when we apply the term “lipoproteins” to blood plasma and other extracellular fluids. These lipoproteins and their role in transport of nonpolar lipids are the subject of this short and eclectic review.
195 citations
TL;DR: Of the individual glycosaminoglycan fractions, only hyaluronic acid showed significant correlation with the biomechanical data, and the possible mechanism of contracture formation was postulated based on these results.
Abstract: The biomechanical changes in rabbit knee contractures were measured after 9 weeks of immobilization. These results were correlated with the biochemical composition of periarticular connective knee tissue of the same knees. The loss of total hexosamine correlates significantly with joint stiffness on an animal-to-animal basis. Total hexosamine also correlates with the energy required cyclicly to flex and to extend the experimental joints. Of the individual glycosaminoglycan fractions, only hyaluronic acid showed significant correlation with the biomechanical data. The possible mechanism of contracture formation was postulated based on these results.
193 citations
TL;DR: The observed gradient in the mean level of serum PG I among the groups of patients studied is similar to that which has been reported for maximally stimulated gastric acid output, suggesting that the secretory potential of the fundic gland mucosa of the stomach may be reflected by the level of PG I in serum.
TL;DR: The results indicate that a significant relationship exists between the concentration of PG I in serum and the acid secretory capacity of the gastric mucosa.
TL;DR: The noncausal structure events demanded by Bell's theorem are shown to follow naturally from a theory of events similar to White-head's as discussed by the authors, and the macroscopic causality structure observed in Nature at the statistical level holds Quantum theory itself emerges naturally, along with the basic analyticity properties of the S-matrix.
Abstract: The noncausal structure events demanded by Bell's theorem are shown to follow naturally from a theory of events similar to White-head's In spite of this noncausal structure on the level of individu al events the macroscopic causality structure observed in Nature at the statistical level holds Quantum theory itself emerges naturally, along with the basic analyticity properties of theS-matrix
TL;DR: In this paper, three classes of location measures are discussed whose estimators are respectively linear functions of order statistics, R-estimators and M-estimateators, and it is argued that such measures can be compared in terms of the (asymptotic) efficiencies of their estimators.
Abstract: Measures of location (without assumption of symmetry) are defined as functionals satisfying certain equivariance and order conditions. Three classes of such measures are discussed whose estimators are respectively linear functions of order statistics, R-estimators and M-estimators. It is argued that such measures can be compared in terms of the (asymptotic) efficiencies of their estimators. Of the three classes considered, it is found that trimmed expectations (and certain other weighted quantiles) are the only ones which are both robust and whose estimators have guaranteed high efficiency relative to the mean X for all underlying distributions.
01 Jan 1975
TL;DR: In this paper, it was shown that the break point energy of the electrons traveling parallel to the local magnetic field is usually between 0.1 and 10 keV, and that the acceleration of these electrons is at most 2 k.
Abstract: Intense beams of electrons travelling parallel to the local magnetic field have been observed at a magnetic latitude of 11° and a radial distance of 6.6 Re. The distribution function for electrons travelling within 8° of the field line direction is typically flat or slightly rising up to a break point beyond which it decreases as v−5 to v−10. The energy corresponding to the break point velocity is usually between 0.1 and 10 keV. These beams are found to occur on closed field lines at the inner edge of the plasma sheet and thus at the root of the earth’s magnetotail. Beams with break point energies greater than 2 k seem to occur only within the first 10 minutes after the onset of hot plasma injection associated with a magnetospheric substorm. Although the origin and destiny of these electrons is as yet unknown, considerations of the total energy and the number of particles transported guarantee that they must play a dominant role in many key magnetospheric processes.
TL;DR: The purpose of this study was to determine the effect of smoking marihuana and of high‐nicotine cigarettes on exercise‐induced angina pectoris.
Abstract: The purpose of this study was to determine the effect of smoking marihuana and of high-nicotine cigarettes on exercise-induced angina pectoris. Smoking 1 marihuana cigarette increased the resting product of systolic blood pressure times heart rate 54%, increased the venous carboxyhemoglobin level, and decreased the exercise time until angina 50% in 10 patients with angina pectoris. Smoking 1 high-nicotine cigarette increased the resting product of systolic blood pressure times heart rate 36%, increased the venous carboxyhemoglobin level, and decreased the exercise time until angina 23%. Smoking either marihuana or high-nicotine cigarettes decreases exercise performance until angina by increasing myocardial oxygen demand and by decreasing myocardial oxygen delivery. Smoking 1 marihuana cigarette decreased the exercise time until angina more than smoking 1 high-nicotine cigarette (p less than 0.001).
TL;DR: An overview of an approach to the definition of descriptive characteristics of populations and their estimation is given in this article, where the emphasis is on the robustness and efficiency of the estimators.
Abstract: An overview is given of an approach to the definition of descriptive characteristics of populations and to their estimation. The emphasis is on the robustness and efficiency of the estimators. Detailed summaries will be found in successive papers of the series dealing with the problems of location, scale and kurtosis.
01 Jan 1975
TL;DR: What physiologists have inferred years ago and epidemiologists suspected only recently, is being proven by clinical investigators, and a new role for carbon monoxide in heart disease is emerging from new research findings.
01 Jan 1975
TL;DR: A method of calculating the expected errors in the parameters is described, and the results of some applications of the method are presented.
Abstract: This paper is concerned with the estimation of parameters when mathematical models are fitted to data. Two new algorithms are presented. The first is fast (economical in computation time), requires no initial estimates, but is not so accurate. The second requires more computation time, and fairly accurate initial estimates, but achieves high accuracy. The models discussed consist of sets of coupled, non-linear differential equations, but the second algorithm is applicable to wider classes of models as well.
TL;DR: In this article, Histological estimates of the numbers of oyster granular basophilic blood cells, or basophils, per oyster were found to differ significantly for various populations of Pacific and American oysters.
TL;DR: Experiments using lights with a range of spectral outputs confirm that the standard yellow "safe" lights do produce photoreactivation by the human but not the Escherichia coli enzyme.
01 Jan 1975
TL;DR: In this article, the existence of a time evolution and a stationary equilibrium measure for the infinite harmonic crystal was proved and the ergodic properties of the system were related in a simple way to the spectrum of the force matrix.
Abstract: We prove the existence of a time evolution and of a stationary equilibrium measure for the infinite harmonic crystal. The ergodic properties of the system are shown to be related in a simple way to the spectrum of the force matrix; when the spectrum is absolutely continuous, as in the translation invariant crystal, the flow is Bernoulli. The quantum crystal is also discussed.
01 Jan 1975
TL;DR: Results indicate that release from cell aging, as measured by the acquisition of unlimited growth potential, is associated with the precancerous state per se, and occurs as an early event in the transition from normal to malignant mammary cells.
Abstract: Serial transplantation of normal mouse mammary gland in young, isogenic hosts results in progressive loss of division potential, and the transplant line is eventually lost. This is interpreted as an expression of senescence at the cell and tissue level, and it inevitably occurs even though experimental conditions for growth are judged to be optimal. An indefinite extension of mammary growth span can be accomplished by transformation of these normal cells into precancerous cell types, which grow as a benign tissue but which may, however, occasionally undergo a second transformation into a malignant carcinoma. All precancerous tissues tested displayed unlimited growth potential, regardless of whether they occurred spontaneously, or were induced by oncogenic viruses or by administration of chemical carcinogens. Precancerous tissues of both ductal and lobuloalveolar morphology grew continuously. These results indicate that release from cell aging, as measured by the acquisition of unlimited growth potential, is associated with the precancerous state per se, and occurs as an early event in the transition from normal to malignant mammary cells.—Daniel, C. W., B. D. Aidells, D. Medina and L. J. Faulkin, Jr. Unlimited division potential of precancerous mouse mammary cells after spontaneous or carcinogen-induced transformation. Federation Proc. 34: 64–67, 1975.
01 Jan 1975
TL;DR: In this article, the authors used the gas transfer equations to investigate the C4 pathway for plants in an arid, desert environment and concluded that the CAM pathway is adaptive to xeric conditions and similar to the C 4 pathway.
Abstract: An investigation of CAM with the use of the gas transfer equations, \({\rm{T = D\Delta /}}{{\rm{R}}_{\rm{a}}}{\rm{ + }}{{\rm{R}}_{\rm{s}}}\) and \({\rm{P = D'\Delta '/}}{{\rm{R}}_{\rm{a}}}{\rm{ + }}{{\rm{R}}_{\rm{s}}}{\rm{ + }}{{\rm{R}}_{\rm{m}}}\) suggests that CAM is adaptive to xeric conditions and similar to the C4 pathway. Transpiration ratios (TR) are low and on the order of 150 whereas for C4-piants and C3-plants they average 300 and 600 respectively. Carbon assimilation efficiency (CAE) estimates, the ratio of P to Pmax where Pmax = \( D'\Delta \sim '({{R}_{a}} + {{R}_{s}}) \) or the estimated CO2 assimilation rate at Rm = O, in the dark are about 0.7–0.9 similarly to C4 plants but unlike C3 estimates of 0.2 to 0.3. We have concluded that the CAM pathway for plants in an arid, desert environment has a two-fold interpretation: primarily, immediately after periods of rainfall and consequent high plant water potentials, nocturnal acidification rates are highest. Minimum TR of 25–70 and maximum CAE values of 0.75–0.82 occur. The level of acid metabolism decreases with decreasing water potential. Secondly, during periods of drought and water potentials of −15 to −20 bars a reduced, but steady level of acidification occurs by the reassimilation of endogenous CO2. Perhaps, further, these plants can shift from the CAM option to the C3 option under extended, favorable conditions.
TL;DR: This paper is an analysis of 95 cases treated surgically at the University of California Hospitals and at Children's Hospital between 1949 and 1971; 92 had abdominal radical surgery and three were done vaginally.