Showing papers by "University of Texas at Austin published in 1971"
Book•
01 Jan 1971TL;DR: In this paper, a comprehensive discussion of heat transfer by thermal radiation is presented, including the radiative behavior of materials, radiation between surfaces, and gas radiation, and the use of the Monte Carlo technique in solving radiant exchange problems and problems of radiative transfer through absorbing-emitting media.
Abstract: A comprehensive discussion of heat transfer by thermal radiation is presented, including the radiative behavior of materials, radiation between surfaces, and gas radiation. Among the topics considered are property prediction by electromagnetic theory, the observed properties of solid materials, radiation in the presence of other modes of energy transfer, the equations of transfer for an absorbing-emitting gas, and radiative transfer in scattering and absorbing media. Also considered are radiation exchange between black isothermal surfaces, radiation exchange in enclosures composed of diffuse gray surfaces and in enclosures having some specularly reflecting surfaces, and radiation exchange between nondiffuse nongray surfaces. The use of the Monte Carlo technique in solving radiant-exchange problems and problems of radiative transfer through absorbing-emitting media is explained.
5,420 citations
Book•
01 Jan 1971TL;DR: A theory of multi-LANE traffic flow and the space-time evolution of thevelocity distribution of cars are examined to help understand the role of driver behaviour and strategy in this network.
Abstract: THE THEORY OF MULTIPLE-LANE TRAFFIC FLOW IS EXAMINED. A PREDICTION OF THE CHARACTER OF THE TRAFFIC FLOW IS MADE AT ARBITARY DENSITY IN TERMS OF DRIVER BEHAVIOR IN DILUTE, NONINTERACTING TRAFFIC, AND A KINETIC EQUATION IS DERIVED TO DESCRIBE THE SPACE-TIME EVOLUTION OF THE VELOCITY DISTRIBUTION OF CARS. THE ANALOGIES THAT EXIST BETWEEN STATISTICAL PHYSICS AND TRAFFIC HAVE BEEN EMPLOYED IN DEVELOPING A VIABLE THEORY. THE PROBLEM IS FORMULATED AND THE THEORY IS DEVELOPED TO A POINT WHERE THE MEETING OF THEORETICAL CONCEPTS WITH EXPERIMENTAL OBSERVATIONS WILL BE FRUITFUL. /AUTHOR/
695 citations
TL;DR: Cycloheximide and related glutarimide antibiotics have been shown to affect binding, transfer enzyme II-dependent movement, and release of transfer RNA from the donor site of reticulocyte ribosomes, as well as both the initiation and extension of globin and phenylalanine peptides.
518 citations
TL;DR: This book is not a survey on theorem proving programs, but the description of a program developed from 1960 to 1965, and includes three chapters that deal with resolution-based theorem-proving in the predicate calculus and its applications to problem solving.
Abstract: This book is not a survey on theorem proving programs, but the description of a program developed from 1960 to 1965. In the first part there are some generalities on artificial intelligence, and in the second part, some logical explanations, necessary for the comprehension of the program. The third part describes the program. The program has three important features:-it is general. It can study more than one formal system. It receives as data the inference rules and the axioms of the formal system which it must study.-it is capable of invention. It can work without knowing the theorem to be proven. It tries to find interesting theorems; it has only the definition of the interest of a theorem.-it proves theorems, but also metatheorems which are new productions and meta-metatheorems which are new means to get productions. This feature has a great heuristic value. This textbook explains the theoretical ideas underlying problem-solving by heuristically guided, trial-and-error search processes. These search methods are explained by the use of a uniform vocabulary, and several theoretical results about the properties of heuristic search are presented. Several simple example problems, puzzles, and games are used to illustrate the techniques. The author refers to instances in which these same techniques have been successfully applied to problems much more complex than the example problems in his book. The book also includes three chapters that deal with resolution-based theorem-proving in the predicate calculus and its applications to problem solving. Each chapter contains exercises and a section on bibliographical and historical remarks that list some of the more important references related to the subject of the chapter.
385 citations
TL;DR: Both responses were greatly enhanced in hypothyroid patients and virtually abolished in hyperthyroid patients, and the possibility that p-Glu-His-Pro-NH2 is also a “natural physiological” regulator of PRL in man is evident.
379 citations
332 citations
TL;DR: In this article, the adaptive estimators are applied to the problem of state estimation with non-Gaussian initial state, to estimation under measurement uncertainty (joint detection-estimation) as well as to system identification.
Abstract: Optimal structure and parameter adaptive estimators have been obtained for continuous as well as discrete data Gaussian process models with linear dynamics. Specifically, the essentially nonlinear adaptive estimators are shown to be decomposable (partition theorem) into two parts, a linear nonadaptive part consisting of a bank of Kalman-Bucy filters and a nonlinear part that incorporates the adaptive nature of the estimator. The conditional-error-covariance matrix of the estimator is also obtained in a form suitable for on-line performance evaluation. The adaptive estimators are applied to the problem of state estimation with non-Gaussian initial state, to estimation under measurement uncertainty (joint detection-estimation) as well as to system identification. Examples are given of the application of the adaptive estimators to structure and parameter adaptation indicating their applicability to engineering problems.
329 citations
TL;DR: This article distinguishes determinant attributes from nondeterminant ones and presents a cross-validation method for testing alternative approaches to identifying these key attributes.
Abstract: Not all product attributes are equally important in determining consumer preferences. This article distinguishes determinant attributes from nondeterminant ones and presents a cross-validation meth...
328 citations
310 citations
TL;DR: In this article, three experiments were designed to demonstrate that objective self-awareness, a state in which the individual evaluates himself and attempts to attain correctness and consistency in his beliefs and behaviors, can mediate both opinion change and performance facilitation.
301 citations
TL;DR: Pharmacologic studies were performed in man with tritiated 1‐β‐D‐arabinofuranosyl cytosine (ara‐C) and the plasma ara‐C deaminase activity was very low, and there was a linear correlation between the dose and plasma concentration of aRA‐C.
Abstract: Pharmacologic studies were performed in man with tritiated 1-β-D-arabinofuranosyl cytosine (ara-C). Most of the plasma and urine radioactivity was in 1-f3-D-arabinofuranosyl uracil (ara-U), and all of the radioactivity could be accounted for as ara-C and ara-U. The plasma disapperance curve of ara-C when plotted on a semilog scale was biphasic with an initial fast phase (mean half-time 12 minutes) and a slower second phase (mean half-time 111 minutes). There was a linear correlation between the dose and plasma concentration of ara-C. The initial plasma ara-U to ara-C ratio was lower at the high doses, suggesting saturation of ara-C deaminase activity. Eighty per cent of the radioactivity was recovered in the urine by 24 hours, 8 per cent as ara-C, and 72 per cent as ara-U. Prior treatment with ara-C had no effect on the pharmacology of ara-C. The plasma ara-C deaminase activity was very low. The total amount in plasma was less than one per cent of that present in the liver. The ara-C deaminase activity of red blood cells (RBC) of normal subjects was 7 per cent that of the liver, and the RBC of solid tumor patients contained significantly higher enzyme activity. Following a loading dose, ara-C was given by constant intravenous infUSion. This resulted in constant plasma ara-C levels which were dose related. At steady state the cerebrospinal fluid (CSF) to plasma ratio of ara-C was 0.4. Intrathecal injection of ara-C resulted in high initial CSF levels and an exponential decrease with a half-time of 2 hours. This very long half-time as compared to the plasma is a function of the very low ara-C deaminase activity in CSF and brain.
TL;DR: Repeat leukapheresis of the same donor does not reduce the number of circulating colony-forming cells in the peripheral blood of man.
Abstract: Colony-forming cells have been found in the peripheral blood of man and have been grown in vitro by use of a soft agar gel technique. It has been possible to collect these cells with a blood-cell separator in numbers similar to those found in the peripheral circulation. Repeat leukapheresis of the same donor does not reduce the number of circulating colony-forming cells.
TL;DR: Adriamycin appears to be promising in several tumors, but maintenance therapy may be precluded by cumulative toxicity, as well as in patients with a variety of tumors.
Abstract: Adriamycin was given to 67 patients with a variety of tumors. The tolerated dose was 20–30 mg/m2/day IV daily for 3 days or 18 mg/m2/day IV daily for 5 days every 3 weeks. Objective responses were seen in transitional cell carcinoma (4/7), liposarcoma (2/2), squamous cell carcinoma (1/9), and adenocarcinoma of the breast (1/1). No responses were seen in other soft tissue sarcomas (10), malignant melanoma (4), acute leukemia (4), lymphoepithelioma (1), or tumors of the gastrointestinal organs (5), thyroid (2), kidney (4), and testis (2). At low doses, nausea and vomiting, phlebitis, and alopecia appeared. At higher doses, mucositis and myelosuppression seem related to the dose of each course, while EKG changes (4 cases) and congestive heart failure (6 cases) appear related to the cumulative dose. EKG changes, consisting of premature ventricular contractions and ST-T wave changes, appeared to be related to adriamycin in 3 cases. The CHF appeared related in 3 cases. Adriamycin appears to be promising in several tumors, but maintenance therapy may be precluded by cumulative toxicity.
TL;DR: Since similar concentrations of (NH4)2SO4 increase the in vitro nuclear RNA synthesis several-fold, it can be concluded that the salt activation ofRNA synthesis in isolated nuclei or chromatin is caused by the activation of RNA synthesis system and not by template derepression of chromatin.
TL;DR: This method is based on the demonstration that nucleotide sequence diversity may be estimated from the kinetics of renaturation of denatured DNA and shows that most of the nucleotide sequences in mouse, Drosophila, and Ciona DNA are present only once per sperm.
Abstract: Models of chromatid structure are based on inferences made from genetic, cytological, and cytochemical observations. An alternative approach can provide limits as to the number of identical subunits present in chromatids. This method is based on the demonstration that nucleotide sequence diversity may be estimated from the kinetics of renaturation of denatured DNA. Measurements of DNA content and renaturation rate constants are given for several eukaryotic DNAs. Control experiments involved measurements of renaturation kinetics of DNAs from bacteria and bacteriophage. These estimates show that most of the nucleotide sequences in mouse, Drosophila, and Ciona DNA are present only once per sperm. Since the reduction of DNA content during meiosis indicates that mouse sperm contain a haploid set of chromatids, it follows that a set of mouse meiotic chromatids contains a single copy of most sequences. Models of chromatid structure which postulate multiple subunits with identical nucleotide sequences are therefore not tenable for mouse meiotic chromatids. This method of analyzing nucleotide sequence diversity may be of general use in designing models of chromatid structure in other organisms.
TL;DR: In this paper, six different estimates of the magnetotelluric impedance tensor elements may be computed from measured data by use of auto-power and cross-power density spectra.
Abstract: Six different estimates of the magnetotelluric impedance tensor elements may be computed from measured data by use of auto-power and cross-power density spectra. We show that each of the estimates satisfies a mean-square error criterion. Two of the six estimates are relatively unstable in the one-dimensional case when the incident fields are unpolarized. For the remaining four estimates, it is shown that two are unaffected by random noise on the H signal, but are biased upward by random noise on the E signal. The
TL;DR: It was demonstrated that DNA prepared from log-phase cells renatures faster than stationary-phase DNA and also departs from theoretical second-order kinetics.
Abstract: The base composition of a deoxyribonucleic acid (DNA) sample affects its intrinsic rate of renaturation. In agreement with the information of Wetmur and Davidson, it was established that high guanosine plus cytosine (GC) DNA renatures faster than expected from analytical measurement of its molecular weight. A calculated correction factor of 1.8% of the observed C0t.5 is required for every mole per cent GC difference from 51% GC. The correction factor is now established in the range of 32 to 65% GC. Renaturation of DNA mixtures prepared from pairs of organisms has been studied. When no similarity existed between the two organisms, the observed C0t.5 of the mixture was the sum of the independently determined C0t.5 values. Lack of additivity was correlated with similarities in polynucleotide sequence of the reassociating DNA molecules. A quantitative relationship was formulated to relate C0t.5 values of renatured DNA mixtures to per cent binding (“homology”). Finally, it was demonstrated that DNA prepared from log-phase cells renatures faster than stationary-phase DNA and also departs from theoretical second-order kinetics.
TL;DR: From the location of the centromeric heterochromatin of the X chromosome in the sex bivalent, it is concluded that the association between the X and Y in meiosis is limited to the distal portions of the sex elements.
Abstract: Applying a staining procedure which reveals constitutive heterochromatin to cytological preparations of the mouse (Mus musculus), one detects heterochromatin pieces at the centromeric areas of all chromosomes except the Y. The Y chromosome is somewhat heteropyenotic in general but possesses no intensely stained centromeric heterochromatin. The arrangement of the centromeric heterochromatin in interphase cells is apparently specific for a given cell type. In meiotic prophase, centromeric heterochromatin may form clusters among bivalents. From the location of the centromeric heterochromatin of the X chromosome in the sex bivalent, it is concluded that the association between the X and Y (common end) in meiosis is limited to the distal portions of the sex elements.
TL;DR: The origin of the longitudinal dune form is reviewed in this article, where the spectacular longitudinal dunes of the Simpson desert are caused by helicoidal wind flow of the prevailing south-southeastern winds, acting upon ancient alluvial plains.
Abstract: Origin of the longitudinal dune form is reviewed. The spectacular longitudinal dunes of the Simpson desert are caused by helicoidal wind flow of the prevailing south-southeastern winds, acting upon ancient alluvial plains. Critical in this theory is the evidence from tuning-fork junctures, which open upwind as do similar features in other geologic realms of primarily one-directional currents undergoing second-order helicoidal circulation.
A summary of previous work on using grain size to distinguish beach from dune sands reveals the consistent good sorting and positive skewness of coastal dunes. Simpson desert dunes are also positively-skewed, but are not as well sorted as coastal dunes because they are only recently derived from poorly-sorted alluvial source sediments. Dune crests are coarsest and best sorted because they are made out of the most easily saltated fine sand (about 2.5 o); windward flanks, leeward flanks, and reg are progressively finer and also show regular and explainable changes in the higher-order grain-size parameters. Both dune and reg sediments are made of polymodal mixtures, giving rise to a “quantum theory” of aeolian deposition.
TL;DR: In the early steady state after small bowel resection, the remaining segment shows hyperplasia with an increase in the number of epithelial cells lining the villous surface, suggesting presumably less mature and smaller cells have diminished disaccharidase and transport activity.
TL;DR: The authors' studies go beyond Calhoun chiefly in detail and show that full appreciation of variation and adaptation of house sparrows in North America is dependent on that detail.
Abstract: With the introduction of the house sparrow Passer domesticus to North America in the period 1852-1860, students of the evolutionary process had a developing case history of adaptation and differentiation set before them. However, the possibilities of gaining evolutionary insight through what Grinnell (1919) was to call \"an experiment in nature\" were not realized for several decades, perhaps because the timing of the initial introductions preceded the Darwinian thesis. But periodically the birds figured in evolutionary thinking, and suggestive instances of what they were experiencing in life in North America were noted by Bumpus (1898a, 1898b), Grinnell (1919), Lack (1940), and Calhoun (1947). In fact, with the appearance of Calhoun's work, a broad base for understanding that the birds had been undergoing adaptive differentiation was thoroughly established. Our studies, of which parts have already appeared (Johnston and Selander, 1964; Selander and Johnston, 1967), go beyond Calhoun chiefly in detail. Notwithstanding, full appreciation of variation and adaptation of house sparrows in North America is dependent on that detail.
TL;DR: Analysis of the membrane lipids of fractions of Tetrahymena pyriformis reveals significant differences in lipid composition, most noteworthy are the high concentrations of phosphonolipid and tetrahymanol in the surface membranes.
Abstract: A method has been devised to fractionate cells of Tetrahymena pyriformis, yielding pure or highly enriched preparations of cilia, cilia-associated soluble material, pellicles, mitochondria, microsomes, and postmicrosomal supernatant. The method prevents the destructive action of lipolytic enzymes commonly associated with this organism. Analysis of the membrane lipids of these fractions reveals significant differences in lipid composition. Most noteworthy are the high concentrations of phosphonolipid and tetrahymanol in the surface membranes.
TL;DR: Deep body temperature of the house sparrow, Passer domesticus, was monitored continuously by radio telemetry and pinealectomy abolished the normal circadian rhythm of body temperature in constant darkness, and significantly altered the amplitude of bodyTemperature rhythms entrained to light cycles.
Abstract: Deep body temperature of the house sparrow, Passer domesticus, was monitored continuously by radio telemetry. Pinealectomy abolished the normal circadian rhythm of body temperature in constant darkness, and significantly altered the amplitude of body temperature rhythms entrained to light cycles. The body temperature minima of pinealectomized birds never fell as low as those of unoperated birds regardless of the light conditions; the temperature maxima of both normal and pinealectomized birds were higher in light than in darkness. In sparrows the pineal organ is essential to the normal function of the biological clock controlling both activity and body temperature rhythms and may be directly involved in thermoregulation.
TL;DR: The survival of patients with lymphosarcoma or reticulum cell sarcoma receiving COP treatment was significantly superior to a comparable group of patients treated sequentially with single agents.
Abstract: A combination of intravenous cyclophosphamide and vincristine (Oncovin) and oral prednisone (COP) was given every 2 weeks to 262 patients with disseminated Hodgkin's disease, lymphosarcoma, reticulum cell sarcoma, and follicular lymphoma. A complete remission was produced in 36% of patients with Hodgkin's disease, 50% of patients with lymphosarcoma, and 39% of patients with reticulum cell sarcoma. These remission rates are significantly superior to those produced by single agents. Patients who achieved a complete remission were randomly allocated to monthly COP (maintained remission) or to no treatment (unmaintained remission). The median duration of maintained remission was longer than unmaintained remission for Hodgkin's disease (42 weeks vs. 19 weeks) and lymphosarcoma (49 weeks vs. 21 weeks) but not for reticulum cell sarcoma (24 weeks vs. 25 weeks). The duration of remission for patients with little or no prior therapy was compared to that for patients in a similar study in which single agents were used.4 For lymphosarcoma and reticulum cell sarcoma, remissions maintained with COP were longer than remissions maintained with cyclophosphamide. For Hodgkin's disease and lymphosarcoma, unmaintained remissions after COP induction were longer than after single agent induction. All parameters of response, that is, complete remission rate, duration of remission, and survival were adversely affected by major prior treatment with radiotherapy and chemotherapy. The initial response to treatment correlated positively with survival. The survival of patients with lymphosarcoma or reticulum cell sarcoma receiving COP treatment was significantly superior to a comparable group of patients treated sequentially with single agents.
TL;DR: In this paper, a general formulation for studies of the vibrational properties of systems which have two-dimensional periodicity and one or two surfaces is given, which is applicable to reconstructed surfaces, surfaces with adsorbed impurity particles, etc., as well as unreconstructed clean surfaces, provided that the 2D periodicity is preserved.
Abstract: A general formulation is given for studies of the vibrational properties of systems which have two-dimensional periodicity and one or two surfaces. Although layered structures and other systems with interfaces fall within the scope of this formulation, the principal motivation is to provide a framework for calculating and interpreting vibrational surface properties. No assumption is made concerning crystal structure, surface orientation, the interaction between particles, or the number of particles per unit cell. Also, the treatment is applicable to reconstructed surfaces, surfaces with adsorbed impurity particles, etc., as well as unreconstructed clean surfaces, provided that the two-dimensional periodicity is preserved. A discussion is given of the properties of the vibrational modes: In general, the displacement ellipse for a given mode can have any orientation. For surfaces with "axial-inversion symmetry," however, one axis of the ellipse is always normal to the surface. If the surface has "complete reflection symmetry" with respect to a given plane, then for any two-dimensional wave vector parallel to the plane the modes will separate into two classes: one-third of the modes will be pure shear-horizontal (SH) modes, and the other two-thirds will be polarized strictly in the sagittal plane. It is possible for surface modes of one class to lie within the bulk subbands of the other class. If the crystal has either axial-inversion symmetry or a three-dimensional center of inversion, then the complex dynamical matrix can be reduced to a real, symmetric matrix of the same size. If both symmetries are present, as is the case for many surfaces of interest, then a further reduction is possible. Finally, notations are suggested for distinguishing two-dimensional vectors and for labeling symmetry points in the two-dimensional Brillouin zone associated with a surface.
TL;DR: Data support the hypothesis that spindle elongation occurs by growth of prepositioned microtubules which "push" the poles apart, and indicates that not all interpolar microtubule extended from pole to pole.
Abstract: The mitotic spindle of many mammalian cells undergoes an abrupt elongation at anaphase. In both cultured rat kangaroo (strain PtK1) and Chinese hamster (strain Don-C) fibroblasts, the distance from pole to pole at metaphase doubles during anaphase and telophase. In order to determine the organization and distribution of spindle microtubules during the elongation process, cells were fixed and flat embedded in Epon 812. Selected cells were photographed with the phase-contrast microscope and then serially sectioned perpendicular to the major spindle axis. Microtubule profiles were counted in selected sections, and the number was plotted with respect to position along the spindle axis. Interpretation of the distribution profiles indicated that not all interpolar microtubules extended from pole to pole. It is estimated that 55–70% of the interpolar microtubules are overlapped at the cell equator while 30–45% extend across the equator into both half spindles. This arrangement appeared to persist from early anaphase (before elongation) until telophase after the elongation process. Although sliding or shearing of microtubules may occur in the spindle, such appears not to be the mechanism by which the spindle elongates in anaphase. Instead, our data support the hypothesis that spindle elongation occurs by growth of prepositioned microtubules which "push" the poles apart.
TL;DR: Observations support the ideas of Rappaport that furrow initiation results from the interaction of pairs of asters with the egg surface, and present the possibility that there are at least two sources of membrane for furrow growth.
TL;DR: A pair grammar is composed of a pair of grammars whose rules and nonterminals are paired that defines a correspondence between elements of the languages defined by the two Grammars.