Showing papers by "University of Texas at Austin published in 1968"

Coupling of substructures for dynamic analyses.

Abstract: A method for treating a complex structure as an assemblage of distinct regions, or substructures, is presented. Using basic mass and stiffness matrices for the substructures, together with conditions of geometrical compatibility along substructure boundaries, the method employs two forms of generalized coordinates. Boundary generalized coordinates give displacements and rotations of points along substructure boundaries and are related to the displacement modes of the substructures known as "constraint modes." All constraint modes are generated by matrix operations from substructure input data. Substructure normal-mode generalized coordinates are related to free vibration modes of the substructures relative to completely restrained boundaries. The definition of substructure modes and the requirement of compatibility along substructure boundaries lead to coordinate transformation matrices that are employed in obtaining system mass and stiffness matrices from the mass and stiffness matrices of the substructures. Provision is made, through a RayleighRitz procedure, for reducing the total number of degrees of freedom of a structure while retaining accurate description of its dynamic behavior. Substructure boundaries may have any degree of redundancy. An example is presented giving a free vibration analysis of a structure having a highly indeterminate substructure boundary.

Capitalism and Underdevelopment in Latin America. Historical Studies of Chile and Brazil

Abstract: The four essays in this book offer a sweeping reinterpretation of Latin American history as an aspect of the world-wide spread of capitalism in its commercial and industrial phases. Dr. Frank lays to rest the myth of Latin American feudalism, demonstrating in the process the impossibility of a bourgeois revolution in a part of the world which is already part and parcel of the capitalist system.

Stimulatory and inhibitory effects of purified hypothalamic extracts on growth hormone release from rat pituitary in vitro.

Abstract: Male rat anterior pituitaries were incubated in vitro for 5 hr in Krebs-Ringer bicarbonate medium and the growth hormone (GH) released from the glands was estimated by the tibial epiphyseal cartilage assay. Addition of crude sheep or rat hypothalamic extract to the pituitaries increased the GH concentration in the medium on comparison to either diluent or cortical extract-treated controls. The ovine extracts also depleted pituitary GH concentration when injected into male rats in vivo. Gel filtration of either sheep or rat hypothalamic extract on a column of Sephadex G-25 resulted in the elution from the column of 2 zones which influenced the release of GH in vitro on addition to the incubated pituitaries. The first zone of activity to be eluted increased the release of GH from the glands severalfold, whereas the second zone inhibited the release of GH to levels about one half of that released by control glands incubated in the presence of the eluting buffer. Increasing the dose in the inhibitory zone res...

Pineal Function: The Biological Clock in the Sparrow?

Abstract: The pineal organ of the house sparrow, Passer domesticus, is essential for persistence of the circadian locomotor rhythm in constant conditions. Upon removal of the pineal body, activity becomes arrhythmic. However, pinealectomy does not abolish the rhythm of locomotor activity in birds exposed to light-dark cycles. Pinealectomized birds are entrained by light cycles in much the same manner as are normal birds. Our data demonstrate that the pineal organ is a crucial component of the endogenous time-measuring system of the sparrow.

Androgen Control of Territorial Marking in the Mongolian Gerbil

Abstract: Gerbils mark objects with the secretion of a midventral sebaceous gland. Both the behavior and the gland integrity are under androgen control, as indicated by castration and replacement with testosterone propionate. The integrity of the gland seems less important for marking than an influence on the central nervous system, although the gland can be used as an external measure of androgen levels. It is possible that the secretion acts as a pheromone to signal territorial possession.

On pigments, growth, and photosynthesis of phaeodactylum tricornutum(1) (2).

Abstract: SUMMARY A maximum growth rate with doubling time of 18 hr at 18 C could be maintained. Continuous cultures at about half maximum growth rate provided cells for study of pigments and photosynthesis. The light intensity curve of photosynthesis had no unusual features and showed light-saturated rates of 30-35 μl O2/mrn3-hr at 18 C. Pigment analysis showed chlorophylls a and c (a/c ratio = 4), fucoxanthin, β-carotene, and diadinoxanthin. Growth under red light (±660 mμ) altered pigments only by decrease in chlorophyll c to about one-half the content obtained under clear tungsten lamps. The large and anomalous spectral shift in fucoxanthin following organic solvent extraction runs confirmed, but efforts to isolate a native fucoxanthin were unsuccessful. Spectral analysis of acetone extracts and sonicated cell preparations allowed estimate of fractional absorption by each component pigment. The analysis shows that chlorophyll a and fucoxanthin are the principal light absorbing pigments and that absorption by other carotenoids is very small.

Acetate Assimilation by Nitrobacter agilis in Relation to Its “Obligate Autotrophy”

Abstract: Acetate (1 to 10 mm) had no effect on the rate of nitrite oxidation or exponential growth by Nitrobacter agilis. However, acetate-1-(14)C and -2-(14)C were both assimilated by growing cultures, and acetate carbon contributed 33 to 39% of newly synthesized cell carbon. Carbon from acetate was incorporated into all of the major cell constituents, including most of the amino acids of cell protein and poly-beta-hydroxybutyrate (PHB). Cultures grown in the presence of acetate showed a significant increase in turbidity, attributable in part to protein synthesis and the accumulation of PHB in the "post-exponential phase," when the supply of nitrite was completely exhausted. Cell suspensons of N. agilis assimilated acetate in the absence of bicarbonate and even in the absence of nitrite. However, the addition of nitrite increased the rate of acetate assimilation by cell suspensions. The distribution of (14)C-acetate incorporated by cell suspensions was qualitatively similar to that found with growing cultures. Cell suspensions of N. agilis slowly oxidized acetate to CO(2). Addition of nitrite suppressed CO(2) production from acetate but increased the assimilation of acetate carbon into cell material. N. agilis contained all the enzymes of the tricarboxylic acid cycle. Growth of N. agilis in the presence of acetate did not significantly affect the levels of the enzymes of the tricarboxylic acid cycle, but did result in a 100-fold increase in the specific activity of isocitratase. In contrast, carboxydismutase was partially repressed. N. agilis was grown heterotrophically through seven transfers on a medium containing acetate and casein hydrolysate. The addition of nitrite increased the rate of heterotrophic growth. Heterotrophically grown organisms still retained their ability to grow autotrophically with nitrite. However, these organisms oxidized nitrite at a slower rate. Organisms from autotrophic and heterotrophic cultures were analyzed to determine the mean guanine plus cytosine content of their deoxyribonucleic acid; in both cases this mean was 61.2 +/- 1%. We concluded that N. agilis is not an obligate autotroph; it appears to be a facultative autotroph which resembles the novel facultative autotroph, Thiobacillus intermedius, very closely.

The Measurement of Modernism: A Study of Values in Brazil and Mexico

Abstract: Preface Chapter I. The Modernization of Values Traditional Society versus Modern Society Causes and Effects Values and Norms Career Values Three Men From Ideal Types to Variables The Components of Modernism Empirical Syndrome of Modernism Conclusions Chapter II. The Operational Definition of Modernism The Questionnaire The Samples The Scales Modernism I Stability of Modernism I in Subsamples Rotation of Axes Modernism II Conclusions Chapter III. Who Are the Modern Men? Component Value Scales Comparisons between Brazil and Mexico: Modernism III Comparisons with the United States Conclusions Chapter IV. Modern Values, Education, and Occupation From School to Job How Much Is an Education Worth? Why Do Boys Stay in School? The Prediction of Education by Father's Status and by Size of Town Values and Education Conclusions Chapter V. Modern Values and Fertility Ideals Fertility Ideals The Role of Values Family Structure in Brazil and Mexico Supporting Evidence on Family Structure Nonfamily Relationships A Theory of Causation Conclusions Chapter VI. Personal Satisfaction and Political Attitudes Job and Career Satisfaction Life Satisfaction Relations among the Three Indices of Satisfaction Satisfaction, Occupation, and Location Time Sequence: Satisfaction Relative to Aspiration Education, Occupation, and Satisfaction Income and Satisfaction Measures of Radical Orientation Status, Satisfaction, and Radicalism Mexican Manual Workers Mexican Nonmanual Workers The Ambivalent Mexican Conclusions Chapter VII. Work Attitudes The Wide Range of Views Specific Job Attitudes Rating by the Boss Conclusions Chapter VIII. Conclusions: Modernism and Development The Value Scales The Typical Modem Man Where Is the Modern Man? Validity of the Tools Values and Education Values and Family Size Satisfaction and Politics Work Attitudes Values: Means or Ends? Values and Economic Development Appendix A. Socio-Economic Status Social Stratification The Respondents' Status Indices Index of SES Measures of Parental Status Social-Class Identification Deviant Cases Time Sequence Multivariate Analysis of Identification Identification as an Intervening Variable Clerks versus Skilled Workers Conclusions Appendix B. Fathers and Sons: Intergenerational Mobility Rates of Mobility: Correlation Coefficients Father's SES, Son's Education, Son's SES Problems of Matrix Analysis of Occupational Mobility Matrices for Brazil and Mexico Education and Mobility Conclusions Appendix C. Portuguese Translation of Value Scales Appendix D. Spanish Translation of Value Scales Bibliography Index

AN ULTRASTRUCTURAL STUDY OF PLANT SPERMATOGENESIS Spermatogenesis in Nitella

Abstract: Spermatogenesis in the charophyte Nitella has been followed in antheridia prepared for light and electron microscopy. The antheridial filament cells contain paired centrioles which are similar in structure and behavior to the centrioles of animal cells. In the early spermatid, the centrioles undergo an initial elongation at their distal ends and become joined by a spindle-shaped fibrous connection. At the same time, their proximal ends are closely associated with the development of a layer of juxtaposed microtubules which will form the microtubular sheath. The architectural arrangement of these microtubules suggests that they constitute a cytoskeletal system, forming a framework along which the mitochondria and plastids become aligned and along which the nucleus undergoes extensive elongation and differentiation. The microtubular sheath persists in the mature sperm. During mid-spermatid stages, the centrioles give rise to the flagella and concomitantly undergo differentiation to become the basal bodies. The Golgi apparatus goes through a period of intensive activity during mid-spermatid stages, then decreases in organization until it can no longer be detected in the late spermatid. An attempt is made to compare similarities between plant and animal spermiogenesis.

Clinical pharmacologic observations on 6-mercaptopurine and 6-methylthiopurine ribonucleoside.

Abstract: Gastrointestinal absorption of 6‐mercaptopurine (MP) was incomplete and variable. After a single intravenous iniection, its plasma half‐life was 21 minutes in children and 47 minutes in adults. However, in 6 hours the cumulative urinary excretion of MP in each was about 20 per cent of the administered dose. The passage of MP into the red blood cells and into the cerebrospinal fluid was minimal. MP was 19 per cent bound to plasma protein. In contrast, the study on 6‐methylthiopurine ribonucleoside (MMPR) showed that the highest plasma level of radioactivity in patients on MMPR‐S35 occurred at 1 to 2 days following both oral and intravenous routes. Gastrointestinal absorption was complete. The half‐life of plasma radioactivity was 5 days. Radioactivity was concentrated within human red blood cells to a 40 to 1 concentration gradient over plasma; the radioactivity was in the form of MMPR 5'‐monophosphate. This anabolite persisted in the red cells for as long as 6 weeks. Excretion of radioactivity was slow and sustained, about 10 per cent daily of the MMPR dose. Only unchanged MMPR was detected in urine during the first day; in later urine samples, principally the 5'‐monophosphate was found. MMPR was largely excluded from the cerebrospinal fluid. It was 39 per cent bound to plasma protein.

Spontaneous seizures in the Mongolian gerbil (Meriones unguiculatus)

Abstract: Approximately 50% of the Mongolian gerbils in our colony were observed to display an epileptiform seizure when placed in a novel area. Forty-six percent of the susceptible animals were descended from two pairs of animals. Stimulus quality seemed to have little bearing on the response, but stimulus intensity was important. Daily exposure to novelty resulted in a progressive loss of seizure activity until no seizures were observed by the fifth day. The peak seizure time was at the height of diurnal behavioral activity. Dilantin, a common anticonvulsant drug used in human epilepsy completely eliminated the seizure as did reserpine. Brain histologies revealed nothing peculiar about the seizing animals. Neither dietary deficiencies nor infections seemed to be involved. The seizure pattern and the conditions under which it occurred suggest a variable genetic threshold response contingent on central nervous system excitation.

Optimal estimation in the presence of unknown parameters

Abstract: An adaptive approach is presented for optimal estimation of a sampled stochastic process with finite-state unknown parameters. It is shown that for processes with an implicit generalized Markov property that the optimal (conditional mean) state estimates can be formed from (i) a set of optimal estimates based on known parameters, and (ii) a set of "learning" statistics which are recursively updated. The formulation thus provides a separation technique which simplifies the optimal solution of this class of nonlinear estimation problems. Examples of the separation technique are given for prediction of a non-Gaussian Markov process with unknown parameters and for filtering the state of a Gauss-Markov process with unknown parameters. General results are given on the convergence of optimal estimation systems operating in the presence of unknown parameters. Conditions are given under which a Bayes optimal (conditional mean) adaptive estimation system will converge in performance to an optimal system which is "told" the value of unknown parameters.

Electron and phase-contrast microscopy of sexual reproduction in chlamydomonas moewusii(1).

Abstract: The sexual process of C. moewusii from gametic activation through germination of the zygote has been studied with phase-contrast and electron microscopy. Long strands emerging from the gametic flagellar tips are the site of early flagellar attraction which is followed by union of compatible flagella within common flagellar sheaths. The gametic connecting strand is formed by coordinated elongation of the plasma papillae of a gametic pair and the penetration of the former through their wall papillae while the flagella are in intimate association. After the free-swimming period, the gametic pairs aggregate in a second period of clumping. The connecting strand is abscised and extruded during plas-mogamy as are the flagellar basal bodies. Evidence is presented which suggests union of the gametic plastids, and stages in karyogamy are illustrated. Formation of the wall layers, accumulation of starch and lipids, and changes in plastid organization in the maturing and germinating zygote are described as is the formation of the gonal walls.

The roots of territorial marking in the Mongolian gerbil: A problem of species-common topography

Abstract: The Mongolian gerbil (Meriones unguiculatus) has recently been introduced into behavioral research. Many features make it an ideal laboratory animal. It is docile, highly exploratory, a good learner, virtually odorless and can be maintained without water; other than that it metabolizes from its food. General characteristics of the gerbil are described, and a brief review of behavioral research is given. The gerbil also possesses unique attributes that can only be studied by matching experimental methodology with species-common responses. Territorial marking is used as example. The gerbil regularly marks objects in an open field by skimming the object with a midventral sebaceous scent gland. The marking and gland are dimorphic, with the male marking about twice as frequently as the female and possessing a gland roughly twice the size. The configuration of the field (object quality) modifies the frequency of the response, as does the time of day the animals are exposed to the field. Androgen levels control the level of marking in the male and female, and the correlations between testis weight, size of the sebaceous gland, secretory output and marking frequency are significant. When a gerbil is introduced into an open field recently contaminated by another gerbil, or when objects are smeared with sebum and placed in the field, the male tends to be more hesitant in several types of behavior. The laboratory measures are internally consistent and congruous with the notion that natural selection has acted to reinforce a hormone-behavior relation of social significance to the gerbil.

Peripheral consideration in improving obturator retention

Abstract: The anatomic features of a maxillary resection are described. A simple geometric principle incorporated in an obturative treatment is explained. The application of such a mechanical action to attain greater retention is offered as a practical feature in the obturator design.

The electronic and ionic structures of metal-ammonia solutions

Abstract: Presently existing data on the properties of liquid metal-ammonia solutions are reviewed critically in relation to physical models and current theory. Emphasis is given to the inter-relation between the electronic properties and the atomic structures of the solutions. The material is organized according to concentration regions characterized by differing electronic and ionic structures. In the very dilute concentration range, 0–10−3 mole per cent metal (MPM), the solutions behave as ideal electrolytes with solvated electrons and solvated positive ions as the ionic species. Association of these species occurs in the dilute region, 10−3–10−1 MPM. We propose that growth of associated complexes into large, metallic clusters occurs in the intermediate region, 10−1—3 MPM. A metal-non-metal transition or, at lower temperatures, a phase separation takes place in the 3–7 MPM concentration range. We give a simplified theory of the Mott transition for these solutions and explore the inter-relation of the Mo...

Electrogenerated chemiluminescence. I. Mechanism of anthracene chemiluminescence in N,N-dimethylformamide solution

Abstract: The electrogenerated chemiluminescence (ECL) of anthracene is characterized by emission at the frequency of anthracene fluorescence and also at longer wavelengths. One longer wavelength component is shown to be caused by emission from anthranol produced by decomposition of the cation radical of anthracene and prbbably excited by energy transfer from excited anthracene. Another component, arising from ECL of anthranol itself, is also observed. revious reports of electrogenerated chemiluminescence (ECL) from anthracene solutions in N,Ndimethylformamide (DMF) have noted that the emission spectrum comprises two or more components. The spectral distribution of the component shortest in wavelength is similar to that of anthracene fluorescence, but the others are broad, structureless, and located toward the red with respect to the first component.2s3 This general behavior is common among several polycyclic hydrocarbons and their derivatives. Presently four alternatives are available to explain the longwavelength emission from these systems. Chandross, Longworth, and Viscoz have proposed the formation of an anthracene excited state dimer (excimer), which radiates to produce the low energy emission. A similar explanation is the formation of an anthracene excited state complex with some other species (exciplex). Both the excimer and the exciplex dissociate into component ground state molecules upon deactivation. Zweig, Maricle, Brinen, and Maurer have suggested that solution phosphorescence may be responsible for the longwavelength emission in some of these systems4 Finally, wes have previously pointed out the possibility of emission from an excited state of a product formed during the reaction of the electrogenerated radical ions with their environment. Anthracene has been chosen for study because it is representative of the class of hydrocarbons exhibiting this behavior and because it is available and easily purified. We have performed a number of experiments designed to aid in identifying the emitting species in the anthracene-DMF system, and to help illuminate the means of exciting the species in so lu t ion which do emit. Experimental Section The anthracene used in all experiments was produced by Matheson Coleman and Bell (mp 215-217”). It was purified by triple recrystallization from Baker Spectroquality benzene and Baker Reagent Grade methanol according to a modification of a procedure available in the l i terat~re .~ A portion of the triply recrystallized (1) (a) National Science Fcundation Predoctoral Fellow; (b) to whom correspondence and requests for reprints should be directed. (2) E. A. Chandross, J. W. Longworth, and R. E. Visco, J . A m . Chem. Soc., 87, 3259 (1965). (3 ) A . J. Bard, I<. S . V. Santhanam, S . A. Cruser, and L. R. Faulkner in “Fluorescence,” G. G. Guilbault, Ed., Marcel Dekker, Inc., New York, N. Y . , 1967, Chapter 14. (4) A. Zweig, D. L. Maricle, J. S . Brinen, and A. H. Maurer, J . Am. Chem. Soc., 89, 473 (1967). material was also resublimed twice in DCICUO. No differences in behavior .were found between the material which had been doubly resublimed after recrystallization and that which had merely been recrystallized thrice. For this reason, most subsequent experiments used only the triply recrystallized anthracene. Fluorescence analysis of cyclohexane solutions of the purified anthracene showed no luminescence bands other than those directly attributable to anthracene.6 Maxima in fluorescence intensity were found at 378, 397, 420, 447, and ca. 475 mp. In particular tetracene was shown by absorption spectroscopy and by fluorescence measurements to be present in amounts less than 0.1 z, since none was detectable by these methods. The solvent used in every case was N,N-dimethylformamide which was also supplied by Matheson Coleman and Bell (bp 152154”). The solvent was further purified,by two methods. Method A involved storing the solvent over anhydrous cupric sulfate for several days to complex water and dimethylamine. The solvent was then decanted and distilled at a reflux ratio of 5 from a glass bead packed column 100 cm high under a nitrogen pressure of 20 mm. The middle fraction was retained for use. Method B also involved storage over anhydrous cupric sulfate For a period of several days. The distillation which followed was under the same conditions as above except that the reflux ratio was unity. Following this distillation, the solvent was stored over Linde Type 4A Molecular Sieves for a period of 48 hr. Then the material was decanted and redistilled using a reflux ratio of .l. Once again, only the middle fraction rvas taken. The solvent was stored under an inert helium atmosphere. Neither solvent batch showed fluorescence bands, even under the most sensitive conditiuris. The supporting electrolyte used in all experiments was tetra-rzbutylammonium perchlorate (TBAP), Polarographic grade, supplied by Southwestern Analytical Chemicals, Austin, Texas. The TBAP was used without further purification, but was dried in a vacuum oven for 48 hr at a temperature of 100” and then stored in a desiccator over magnesium perchlorate. The TBAP contained no fluorescent impurities. The electrolysis cell used for ECL emission measurements consisted of two platinum helices inserted through graded seals into the Pyrex wall of a 14/35 standard taper joint, as shown in Figure 1. An adapter was provided so that the cell could be evacuated easily. The electrodes were 2-5 mm apart. It was generally found that greatest emission intensities were incident upon the monochromator entrance slits when the slits and the two electrodes were arranged colinearly. This arrangement was used uniformly in the experiments. Immediately after loading the cell, it was degassed on a vacuum line similar to that described previously7 using two freeze-pumpthaw cycles. Minimum pressure over the frozen solution on the second cycle was at most 10-4 torr in every case. The voltage applied to the cell was simply the 60-cycle sinusoidally alternating line voltage which was reduced from 110 V root mean square to any (5) T. Takeuchi and M . Furusawa, Kogpo Kagaku Zasshi, 68, 474 ( 6 ) I. Berlman, “Handbook of Fluorescence Spectra of Organic (7) K. S. V. Santhanam and A. J. Bard, J . A m . Chem. Soc., 88, 2669 (1965); Chem. Abstr., 63, 4060e (1965). Molecules,” Academic Press, New York, N . Y., 1965.