Showing papers by "University of Colorado Boulder published in 1985"

Control of eukaryotic messenger RNA synthesis by sequence-specific DNA-binding proteins

Abstract: The enzymatic machinery that carries out RNA synthesis provides the cell with the means to adjust the patterns of transcription in response to environmental and developmental signals. In eukaryotes, this regulation is mediated in part by promoter-specific transcription factors, which are DNA-binding proteins with the ability to discriminate between distinctive DNA sequence elements found in the promoter regions of different genes. The presence of these factors bound to DNA enables other components of the transcriptional machinery, including the RNA polymerase, to initiate transcription with selectivity and accuracy.

Radio Emission from the Sun and Stars

Abstract: Radio astronomy of the sun has reached a high level of maturity, while radio astronomy of the stars is now a burgeoning new field of study. The present review is mainly concerned with radiation which is emitted by 'normal' stars, defined here to include those appearing on classical Hertzsprung-Russell diagrams. The mechanisms for both steady, quiescent emission and intense, strongly varying outbursts are discussed. Included are discussions of bremsstrahlung, gyrosynchrotron emission, electron-cyclotron masers, and plasma radiation. The manifestation of these mechanisms in various kinds of solar radiation are considered along with stellar manifestations.

Gene synthesis machines: DNA chemistry and its uses

Abstract: Deoxyoligonucleotides can now be synthesized rapidly and in high yield because of recent advances in nucleic acid chemistry. Key innovations include solid-phase synthesis on silica-based supports and the development of stable deoxynucleoside phosphoramidites as synthons. When incorporated into manual, semiautomatic, or automatic instruments, these new procedures can be used to prepare probes, mixed probes, deoxyoligonucleotides for priming DNA synthesis, analogues of deoxyoligonucleotides, and DNA segments containing more than 100 deoxynucleotides.

Human migration: theory, models, and empirical studies.

Abstract: A general review of studies on internal migration within the United States since 1970 is presented. The author first describes the changes that have occurred during the recent past in U.S. internal migration patterns. The state of knowledge concerning these changes is also assessed. A more abstract discussion of the determinants of migration covering both the theoretical and empirical literature is then presented. Next the empirical findings associated with several new time-series migration data sets are reviewed and the application of econometric methodologies to temporal models of migration is considered. The review concludes with a summary of recent research results and some pointers for future research.

Multiple Regression Analysis of Twin Data

Abstract: A multiple regression model for the analysis of twin data is described in which a cotwin's score is predicted from a proband's score and the coefficient of relationship (R=1.0 and 0.5 for identical and fraternal twin pairs, respectively). This model is especially appropriate for the analysis of data on twins in which one member of each pair has been selected because of a deviant score, e.g., low reading performance. When the model is fitted to such data, the partial regression of the cotwin's score on the coefficient of relationship provides a powerful test of the extent to which the difference between the mean for probands and that for the unselected population is heritable, i.e., a test for genetic etiology. By fitting an augmented model containing an interaction term to either selected or unselected data sets, direct estimates of heritability and the proportion of variance due to shared environmental influences can also be obtained (subject, of course, to the usual assumptions underlying twin analyses, e.g., a linear polygenic model, little or no assortative mating, and equal shared environmental influences for identical and fraternal twins).

A federated architecture for information management

Abstract: An approach to the coordinated sharing and interchange of computerized information is described emphasizing partial, controlled sharing among autonomous databases. Office information systems provide a particularly appropriate context for this type of information sharing and exchange. A federated database architecture is described in which a collection of independent database systems are united into a loosely coupled federation in order to share and exchange information. A federation consists of components (of which there may be any number) and a single federal dictionary. The components represent individual users, applications, workstations, or other components in an office information system. The federal dictionary is a specialized component that maintains the topology of the federation and oversees the entry of new components. Each component in the federation controls its interactions with other components by means of an export schema and an import schema. The export schema specifies the information that a component will share with other components, while the import schema specifies the nonlocal information that a component wishes to manipulate. The federated architecture provides mechanisms for sharing data, for sharing transactions (via message types) for combining information from several components, and for coordinating activities among autonomous components (via negotiation). A prototype implementation of the federated database mechanism is currently operational on an experimental basis.

Anisotropic scattering of electrons by N2 and its effect on electron transport.

Abstract: As part of a systematic study of approximations commonly made in solutions of the Boltzmann equation for electrons in molecular gases, we have investigated the effects of anisotropic scattering on electron transport coefficients in ${\mathrm{N}}_{2}$ and have extended our study of the multiterm expansion technique to higher E/n. A critical survey of published data yields a set of differential and integral cross sections for electron energies from 0.003 to ${10}^{4}$ eV. For electric-field--to--gas-density ratios E/n between 10 and 500 Td (1 Td${=10}^{\mathrm{\ensuremath{-}}21}$ V ${\mathrm{m}}^{2}$), the changes in the commonly measured transport and reaction coefficients resulting from the introduction of anisotropic elastic and inelastic scattering, while keeping the elastic momentum-transfer cross section constant, are less than 1%.These calculations were made with use of the multiterm spherical-harmonic expansion solution of the Boltzmann equation. For 500lE/nl1500 Td the changes in scattering anisotropy cause changes in transport and reaction coefficients which increase with E/n to about 10%. The errors in drift velocity, mean energy, and the reaction coefficients resulting from the use of the two-term spherical-harmonic expansion rather than a six-term expansion are less than 3% at 1500 Td.However, the errors in the diffusion coefficients become large (g25%) at our highest E/n. The calculated transport coefficients are in generally good agreement with experiment for E/n less than 300 Td, but the differences increase at higher E/n. The importance of proper interpretation of ionization and excitation experiments at high E/n is illustrated by calculations which model either an exponential growth of density in time or an exponential growth with position. The calculated ionization coefficients are low compared to most experiments for E/n less than 200 Td. At E/ng600 Td the agreement is good for the spatial growth experiments, but the calculated values are below experiment from the temporal growth experiments. The calculated excitation coefficients are generally higher than experiment at low and high E/n but in agreement with experiment at E/n near 150 Td.

Limiting and realizable efficiencies of solar photolysis of water

Abstract: A critical analysis of various schemes for the solar photolysis of water into hydrogen and oxygen places ideal limits on their efficiencies. Single-bandgap schemes will have practical efficiencies of up to 10%, but the prospects of higher efficiencies from dual-bandgap schemes are encouraging.

A Factor Analysis of Self‐Report Measures of Family Functioning

Abstract: Four well-known, self-report measures of family functioning were serially examined in order to identify a limited set of reliable concepts for describing families. Following the completion of four separate data collection procedures, a 75-item scale comprising 15 dimensions of family functioning was constructed. The dimensions appear reasonably independent of each other and have satisfactory psychometric properties. An initial effort to validate the scales was undertaken by contrasting scale scores obtained from descriptions of intact families with those obtained from descriptions of families that subsequently were disrupted by separation and divorce. Significant differences in scale scores were obtained on 12 of the 15 dimensions of family functioning. The 15 dimensions of family functioning could be subsumed under the three general headings suggested by Moos, Insel, and Humphrey (14)--relationship dimensions, personal growth or value dimensions, and system maintenance dimensions.

Extrachromosomal DNA transformation of Caenorhabditis elegans.

Abstract: DNA was introduced into the germ line of the nematode Caenorhabditis elegans by microinjection. Approximately 10% of the injected worms gave rise to transformed progeny. Upon injection, supercoiled molecules formed a high-molecular-weight array predominantly composed of tandem repeats of the injected sequence. Injected linear molecules formed both tandem and inverted repeats as if they had ligated to each other. No worm DNA sequences were required in the injected plasmid for the formation of these high-molecular-weight arrays. Surprisingly, these high-molecular-weight arrays were extrachromosomal and heritable. On average 50% of the progeny of a transformed hermaphrodite still carried the exogenous sequences. In situ hybridization experiments demonstrated that approximately half of the transformed animals carried foreign DNA in all of their cells; the remainder were mosaic animals in which some cells contained the exogenous sequences while others carried no detectable foreign DNA. The presence of mosaic and nonmosaic nematodes in transformed populations may permit detailed analysis of the expression and function of C. elegans genes.

An age comparison of the rates of acquisition and forgetting of spatial information in relation to long-term enhancement of hippocampal synapses.

Abstract: Age differences in the rates of acquisition and forgetting of a spatial memory problem were compared with corresponding differences in the rates of increase and decay of long-term synaptic enhancement (LTE) of hippocampal synapses, induced by high-frequency stimulation of perforant path fibers. Old animals approached their final asymptotic performance levels more slowly than did the young animals and exhibited faster rates of forgetting of the problem. Similarly, LTE reached its maximum more slowly in the old animals and decayed more quickly. Although the absolute rates of behavioral acquisition and forgetting were different from the corresponding rates of increase and decay of LTE, the relative differences between age groups were rather similar. This was particularly true for the comparison of forgetting with LTE decay. The relation of these data to the hypothesis that LTE underlies spatial learning and memory is discussed.

Deformation induced by polar motion

Abstract: Variations in the geocentric position of the earth's rotation axis (polar motion) cause deformation within the earth. The effects of this deformation on radial and horizontal positions of points on the earth's surface, on baseline lengths between those points, and on surface gravity are estimated. The effects of the oceans and of the earth's anelasticity on this deformation are found to be negligible. Peak-to-peak variations in radial motion are typically 10-20 mm over a year. Horizontal displacements are less than 7-8 mm. Variations in baseline length can be as large as 30-40 mm. Variations of up to 13 microgal in surface gravity are possible. These numbers are all small enough that they can probably not be used to learn about the earth. However, they are large enough to affect noticeably present high-quality geodetic observations.

Identification of kinesin in sea urchin eggs, and evidence for its localization in the mitotic spindle.

Abstract: To understand the molecular basis of microtubule-associated motility during mitosis1,2, the mechanochemical factors that generate the relevant motile force must be identified. Myosin, the ATPase that interacts with actin to produce the force for muscle contraction and other forms of cell motility3, is believed to be involved in cytokinesis but not in mitosis4–7. Dynein, the mechanochemical enzyme that drives microtubule sliding in eukaryotic cilia and flagella8,9, has been identified in the cytoplasm of sea urchin eggs10–19, but the evidence that it is involved in cytoplasmic microtubule-based motility (rather than serving as a precursor for embryonic cilia) is equivocal. Microtubule-associated ATPases have been prepared from other tissues (reviewed in ref. 12), but their role in cytoplasmic motility is also unknown. Recent work on axoplasmic transport, however, has led to the identification of a novel mechanochemical protein called kinesin20, which is thought to generate the force for moving vesicles along axonal microtubules20–27. These results suggest that kinesin may also be a mechanochemical factor for non-axoplasmic forms of microtubule-based motility, such as mitosis. We describe here the identification and isolation of a kinesin-like protein from the cytoplasm of sea urchin eggs. We present evidence that this protein is localized in the mitotic spindle, and propose that it may be a mechanochemical factor for some form of motility associated with the mitotic spindle.

Cultivation, frozen storage, and clonal growth of normal human epidermal keratinocytes in serum-free media

Abstract: Methods are described for serum-free culture of human epidermal keratinocytes derived from neonatal foreskin tissue. Cultures are initiated, stored frozen, and returned to active growth, all with bovine pituitary extract as the only undefined supplement. Clonal growth assays are then performed in a biochemically defined medium. The degree of stratification and differentiation in the defined medium (and also with pituitary extract) is controlled by the extracellular calcium ion concentration.

The density of integer points on homogeneous varieties

Abstract: A. The setting

Methylene: A study of the X̃ 3B1 and ã 1A1 states by photoelectron spectroscopy of CH−2 and CD−2

Abstract: Photoelectron spectra are reported for the CH2(X 3B1)+e−←CH−2 (X 2B1) and CH2(a 1A1)+e−←CH−2 (X 2B1) transitions of the methylene and perdeuterated methylene anions, using a new flowing afterglow photoelectron spectrometer with improved energy resolution (11 meV). Rotational relaxation of the ions to ∼300 K and partial vibrational relaxation to <1000 K in the flowing afterglow negative ion source reveal richly structured photoelectron spectra. Detailed rotational band contour analyses yield an electron affinity of 0.652±0.006 eV and a singlet–triplet splitting of 9.00±0.09 kcal/mol for CH2. (See also the following paper by Bunker and Sears.) For CD2, results give an electron affinity of 0.645±0.006 eV and a singlet–triplet splitting of 8.98±0.09 kcal/mol. Deuterium shifts suggest a zero point vibrational contribution of 0.27±0.40 kcal/mol to the observed singlet–triplet splitting, implying a Te value of 8.7±0.5 kcal/mol. Vibrational and partially resolved rotational structure is observed up to ∼9000 c...

A naturalistic study of the meanings of touch

Abstract: The present study employed an adapted version of the contextual analysis method developed by Scheflen and others to examine the meanings‐in‐context of touches reported by persons from their daily interactions. The results revealed 12 distinct and relatively unambiguous meanings: support, appreciation, inclusion, sexual interest or intent, affection, playful affection, playful aggression, compliance, attention‐getting, announcing a response, greetings, and departure. There were also several kinds of hybrid meanings, the main ones being greeting/affection and departure/affection, and four categories of potentially ambiguous touches: reference to appearance, instrumental ancillary, instrumental intrinsic, and accidental. Finally, the analysis revealed a number of types of “touch sequences,” patterns of behavior consisting of a series of related touches, which took two primary forms, repetitive sequences and strategic sequences. These results are discussed in terms of three emergent generalizations about the ...

Laser photodetachment measurement of the electron affinity of atomic oxygen.

Abstract: The electron affinity of atomic oxygen, an important calibration standard in negative-ion photoelectron spectroscopy, has been determined by tunable-laser photodetachment in a coaxial laser--ion-beam spectrometer to be 11 784.645\ifmmode\pm\else\textpm\fi{}0.006 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. In addition, the spin-orbit splitting between the $^{2}\mathrm{P}_{3/2}$ and $^{2}\mathrm{P}_{1/2}$ states of ${\mathrm{O}}^{\mathrm{\ensuremath{-}}}$ was found to be 177.13\ifmmode\pm\else\textpm\fi{}0.05 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$.

Nonradiating edges and four edges gap-coupled multiple resonator broad-band microstrip antennas

Abstract: Two novel configurations for increasing the impedance bandwidth of the microstrip patch antennas are described. One of these configurations uses two additional resonators which are gap-coupled to the nonradiating edges of a rectangular patch, whereas in the second case, four additional resonators are gap-coupled to the four edges of a rectangular patch. Green's function approach and segmentation method are used for analysis. The experimental results are in reasonable agreement with analysis and impedance bandwidths of 480 MHz and 815 MHz are obtained for the three resonators and five resonators configurations, respectively (in S -band with substrate \epsilon_{r} = 2.55 and thickness = 0.318 cm).

Manipulation of the morphogenetic pathways of tobacco explants by oligosaccharins

Abstract: Acquiring the ability to regulate morphogenesis in plants has long been an elusive goal. Previous research has established that ‘thin cell-layer’ explants from the surface of the floral branches of tobacco can be induced to form either callus, vegetative buds, flowers or roots by adjusting the pH and the ratio of auxin to cytokinin in the culture medium1–5. We now report that oligosaccharins (oligosaccharides with regulatory activity) derived from plant cell walls can, at concentrations of ∼10−8 or 10−9 M, induce tobacco expiants to form vegetative buds instead of flowers or callus, or flowers instead of vegetative buds. Other oligosaccharins can induce the expiants to form roots instead of vegetative buds. This ability of oligosaccharins to control morphogenesis suggests that these fragments are in situ regulators of morphogenesis.

The Concept of Health Promotion and the Prevention of Adolescent Drug Abuse

Abstract: A three-dimensional conceptual model for health promotion interventions to prevent adolescent drug abuse is elaborated. The model is based on an analysis of the concept of health into four domains--physical, psychological, social, and personal; an analysis of intervention approaches to change behavior into two major strategies--introducing/strengthening health-enhancing behavior, and weakening/eliminating health-compromising behavior; and an analysis of the foci of interventions into three levels--environmental, personality, and behavior. Components of a specific health promotion program, the Minnesota Heart Health Program, that are designed to prevent adolescent drug abuse are described. These include health behavior campaigns, educational interventions, and community organization. The theoretical content of the components is shown to be linked logically to the health promotion model.

A modular system of algorithms for unconstrained minimization

Abstract: We describe a new package, UNCMIN, for finding a local minimizer of a real valued function of more than one variable. The novel feature of UNCMIN is that it is a modular system of algorithms, containing three different step selection strategies (line search, dogleg, and optimal step) that may be combined with either analytic or finite difference gradient evaluation and with either analytic, finite difference, or BFGS Hessian approximation. We present the results of a comparison of the three step selection strategies on the problems in More, Garbow, and Hillstrom in two separate cases: using finite difference gradients and Hessians, and using finite difference gradients with BFGS Hessian approximations. We also describe a second package, REVMIN, that uses optimization algorithms identical to UNCMIN but obtains values of user-supplied functions by reverse communication.