Showing papers by "University of Arizona published in 1980"

Cordilleran suspect terranes

Abstract: Over 70% of the North American Cordillera is made up of ‘suspect terranes’. Many of these geological provinces are certainly allochthonous to the North American continent and seem to have been swept from far reaches of the Pacific Ocean before collision and accretion into the Cordilleran margin mostly in Mesozoic to early Cenozoic time.

Effect of an intense electromagnetic field on a weakly bound system

Abstract: The approximation method introduced by Keldysh is revised and extended. The technique is applicable to the photodetachment by a plane-wave field of an electron bound by a short-range potential. The approximation is to neglect the effect of the binding potential as compared to the field effects on the final state of the detached electron. By choice of a different gauge than that used by Keldysh, the formalism becomes very simple and tractable. A general basis for the formalism is developed, and it is then applied to find transition probabilities for any order of interaction for both linearly and circularly polarized plane-wave fields. The low-intensity, first-order limit and the high-intensity, high-order limit yield the correct results. Two intensity parameters are identified. The fundamental one is $z=\frac{{e}^{2}{a}^{2}}{4m\ensuremath{\omega}}$, where $a$ is the magnitude of the vector potential (in radiation gauge) of the field of circular frequency $\ensuremath{\omega}$. The second parameter is ${z}_{1}=\frac{2z\ensuremath{\omega}}{{E}_{B}}$, where ${E}_{B}$ is binding energy, and it becomes important only in the asymptotic case. With the assumption that the field leaves the neutral atomic core relatively unaffected, the formalism is applied to the example of the negative hydrogen ion irradiated by circularly or linearly polarized 10.6-\ensuremath{\mu}m radiation. Photodetachment angular distributions and total transition probabilities are examined for explicit intensity effects. It is found that total transition probability $W$ is not sensitive to intensity since $\frac{d(logW)}{d}$ ($logz$) retains low-intensity straight-line behavior up to quite high values of $z$. An important intensity effect is the major significance of higher-than-lowest-order terms when $z$ is large, especially for circular polarization. A sensitive indicator of intensity is the ratio of photodetachment probabilities in circularly and linearly polarized fields, which increases sharply with intensity. An investigation of the convergence of perturbation expansions gives the upper limit $zl[\frac{{E}_{B}}{\ensuremath{\omega}}]\ensuremath{-}\frac{{E}_{B}}{\ensuremath{\omega}}$, where the square bracket means "smallest integer containing" the quantity in brackets. This limit is $zl0.59$ for ${\mathrm{H}}^{\ensuremath{-}}$ in 10.6-\ensuremath{\mu}m radiation. The failure of perturbation theory is not necessarily manifest in qualitative ways. For example, it is not apparent in total photoelectron yield as a function of intensity.

Smoke and Dust Particles of Meteoric Origin in the Mesosphere and Stratosphere

Abstract: A height profile of ablated mass from meteors is calculated, assuming an incoming mass of 10 to the -16th g/sq cm/s (44 metric tons per day) and the velocity distribution of Southworth and Sekanina, which has a mean of 14.5 km/s. The profile peaks at 84 km. The fluxes of micrometeorites and residual meteoroids are also calculated. The coagulation of the evaporated silicates into 'smoke' particles is then followed by means of a model adapted from a previous study of the stratospheric sulfate layer. Numerous sensitivity tests are made. Features of the results are a sharp cutoff of the particle distribution above 90 km, and a surface area close to 10 to the -9th sq cm/cu cm all the way from 30 to 85 km. Some confirmation is obtained from balloon studies of condensation nuclei, although the various measurements differ greatly. The optical scattering and extinction are shown to be undetectable. Several potential applications are suggested: nucleation of sulfate particles and noctilucent clouds, scavenging of metallic ions and atoms, and perhaps other aeronomical effects. The latter are limited to processes that can be influenced by a collision time of the order of a day.

4-Norleucine, 7-D-phenylalanine-alpha-melanocyte-stimulating hormone: a highly potent alpha-melanotropin with ultralong biological activity.

Abstract: alpha-Melanocyte-stimulating hormone (alpha-MSH) reversibly darkens frog skins by stimulating melanosome movement (dispersion) within melanophores. Heat-alkali treatment of alpha-MSH results in prolonged biological activity of the hormone. Quantitative gas chromatographic analysis of the hydrolyzed heat-alkali-treated peptide revealed partial racemization particularly at the 4(methionine) and 7(phenylalanine) positions. [Nle4]-alpha-MSH, a synthetic analogue of alpha-MSH, reversibly darkens frog skins and also exhibits prolonged activity after heat-alkali treatment. Synthesis of [Nle4, D-Phe7]-alpha-MSH provided an analogue with prolonged biological activity identical to that observed with heat-alkali-treated alpha-MSH or [Nle4]-alpha-MSH. [Nle4, D-Phe7]-alpha-MSH was resistant to enzymatic degradation by serum enzymes. In addition, this peptide exhibited dramatically increased biological activity as determined by frog skin bioassay, activation of mouse melanoma adenylate cyclase, and stimulation of mouse melanoma cell tyrosinase activity. This Nle4, D-Phe7 synthetic analogue of alpha-MSH is a very porent melanotropin, 26 times as potent as alpha-MSH in the adenylate cyclase assay. The resistance of the peptide to enzymatic degradation and its extraordinarily potent and prolonged biological activity should make this analogue of alpha-MSH an important molecular probe for studying the melanotropin receptors of both normal and abnormal (melanoma) melanocytes.

Multiphase averaging and the inverse spectral solution of the Korteweg—de Vries equation

Abstract: Inverse spectral theory is used to prescribe and study equations for the slow modulations of N-phase wave trains for the Korteweg-de Vries (KdV) equation. An invariant representation of the modulational equations is deduced. This representation depends upon certain differentials on a Riemann surface. When evaluated near ∞ on the surface, the invariant representation reduces to averaged conservations laws; when evaluated near the branch points, the representation shows that the simple eigenvalues provide Riemann invariants for the modulational equations. Integrals of the invariant representation over certain cycles on the Riemann surface yield “conservation of waves.” Explicit formulas for the characteristic speeds of the modulational equations are derived. These results generalize known results for a single-phase traveling wave, and indicate that complete integrability can induce enough structure into the modulational equations to diagonalize (in the sense of Riemann invariants) their first-order terms.

Biological effects of residual glutaraldehyde in glutaraldehyde‐tanned collagen biomaterials

Abstract: Glutaraldehyde is commonly used to control physical and biological properties of collagen structure by means of intramolecular and/or intermolecular crosslinking of collagen molecules. Solubility, antigenicity, and biodegradation of naturally occurring or reconstituted collagenous matrices are effectively reduced by glutaraldehyde treatment. Adverse biological reactions to glutaraldehyde have been limited to infrequent contact dermatitis and to biocidal effects which are exploited in chemical sterilization media. In the present study of glutaraldehyde-tanned collagen sponge, the presence of glutaraldehyde was correlated with cytotoxic effects upon fibroblasts in tissue culture and foreign body giant cell reaction to bioimplants of the sponge. Fibroblast growth in tissue culture is 99% inhibited at media concentrations of 3.0 ppm glutaraldehyde. Extracts of glutaraldehyde collagen sponge in aqueous media at pH 7 and 4.5 yielded 6 micrograms and 65 micrograms glutaraldehyde per gram of collagen sponge, respectively. The yield increased tenfold at pH 4.5. Observations indicate that leaching of the glutaraldehyde from glutaraldehyde-tanned collagen sponge is sufficient to produce potentially adverse cellular effects both in vivo and in vitro.

Variations on the Common Subexpression Problem

Abstract: Let G be a directed graph such that for each vertex v in G, the successors of v are ordered Let C be any equivalence relation on the vertices of G. The congruence closure C* of C is the finest equivalence relation containing C and such that any two vertices having corresponding successors equivalent under C* are themselves equivalent under C* Efficient algorithms are described for computing congruence closures in the general case and in the following two special cases. 0) G under C* is acyclic, and (it) G is acychc and C identifies a single pair of vertices. The use of these algorithms to test expression eqmvalence (a problem central to program verification) and to test losslessness of joins in relational databases is described

Fatigue under Wide Band Random Stresses

Abstract: A method for predicting high cycle fatigue under stationary gaussian wide band stress processes is developed. The rainflow cycle counting method is used as the basis for predicting fatigue damage. Stress simulations from various spectral density models were analyzed using the rainflow method. Statistical analysis of these results provided a closed form expression for fatigue damage. A principal application of the method is to predict fatigue in the welded joints of offshore structures, an example of which is provided. A long term nonstationary sea state is modelled as a sequence of stationary sea states. Thus the example also illustrates how fatigue under certain types of nonstationary stress processes can be analyzed.

Avian flocking in the presence of a predator

Abstract: Although there are several possible advantages of flocking1–3, many authors suggest that birds forage in groups to reduce the risk of predation (see citations in ref. 4). One version of the ‘many eyes’ hypothesis proposes that flocking allows individuals to spend less time scanning for predators and more time feeding5,6. However, flocking may also cause individuals to lose time and energy in fighting one another. The way a bird divides its time among these activities, its time budget, may depend on variables governing foraging requirements and the chance of predation7. As one such variable is the frequency of attacks by predators8, we flew a trained hawk over flocks of granivorous yellow-eyed juncos (Junco phaeonotus) to compare time budgets in the presence and absence of a predator. We found that time budgets changed after the predator was introduced and also that flock size increased in the presence of the predator.

Normal fluctuations and the FKG inequalities

Abstract: In a translation invariant pure phase of a ferromagnet, finite susceptibility and the FKG inequalities together imply convergence of the block spin scaling limit to the infinite temperature Gaussian fixed point. This result is presented in a rather general probabilistic context and is applicable to infinite cluster density fluctuations in percolation models and to boson field fluctuations in (Euclidean) Yukawa quantum field theory models as well as to magnetization fluctuations in Ising models.

A Rating Scale for Measuring Product/ Service Satisfaction:

Abstract: A simple yet effective rating scale measure of satisfaction has been developed by sociological researchers studying the perceived quality of life. The author examines the suitability of this measur...

Wood-Rotting Fungi of North America

Abstract: The biology of wood-rotting fungi is reviewed. Discussions are presented in taxonomy, species diversity, North American distribution, developmental response to environmental factors, edibility and toxicity, medical uses, relationships of fungi with insects and birds, the role of fungi as mycorrhiza, pathological relationships with trees, role in wood decay, and ecology. Threats to the continuing existence of these fungi as a result of increased utilization of wood as fuel are also discussed. (ACR)

Work and Revolution in France: The Language of Labor from the Old Regime to 1848

Abstract: Work and Revolution in France is particularly appropriate for students of French history interested in the crucial revolutions that took place in 1789, 1830, and 1848. Sewell has reconstructed the artisans' world from the corporate communities of the old regime, through the revolutions in 1789 and 1830, to the socialist experiments of 1848. Research has revealed that the most important class struggles took place in craft workshops, not in 'dark satanic mills'. In the 1830s and 1840s, workers combined the collectivism of the corporate guild tradition with the egalitarianism of the revolutionary tradition, producing a distinct artisan form of socialism and class consciousness that climaxed in the Parisian Revolution of 1848. The book follows artisans into their everyday experience of work, fellowship, and struggles and places their history in the context of wider political, economic, and social developments. Sewell analyzes the 'language of labor' in the broadest sense, dealing not only with what the workers and others wrote and said about labour but with the whole range of institutional conventions, economic practices, social struggles, ritual gestures, customs, and actions that gave the workers' world a comprehensive shape.

Ground‐Water Tracers — A Short Review

Abstract: Tracers are used widely to determine the direction and velocity of ground-water movement. Failures of tracer tests are most commonly a result of incorrect choice of tracers, insufficient concentrations of tracers, and a lack of an understanding of the hydrogeologic system being tested. Some of the most useful general tracers are bromide chloride, rhodamine WT, and various fluorocarbons. For certain purposes, dyed clubmoss and baker's yeast have proved valuable. Many radionuclides including 3H, 82Br, and 198Au are almost ideal for numerous purposes, but radiation hazards associated with their use together with local, State, and Federal regulations have discouraged widespread field applications in recent years within the United States.

Dyslexia: regional differences in brain electrical activity by topographic mapping.

Abstract: Electroencephalographic (EEG) and evoked potential data were recorded during behavioral testing from 8 dyslexic and 10 normal boys aged 9 to 11 years. Topographic mapping of their brain electrical activity revealed four discrete regions of difference between the two groups involving both hemispheres, left more than right. Aberrant dyslexic physiology was not restricted to a single locus but was found in much of the cortical region ordinarily involved in reading and speech. Prominent group differences were observed in the bifrontal area in addition to the more expected left temporal and left posterior quadrant regions. Although activation tests produced more prominent group difference, dyslexics differed from normal subjects at rest as well. EEG alpha activity was increased for the dyslexics, suggesting relative cortical inactivity in that group.

The Myogenic Response

Abstract: Much of the early evidence for the myogenic response was obtained from in vivo experiments on whole organs. Bayliss’ classie studies of the myogenic response1 included both in vivo and in vitro preparations, but data were presented only on in vivo measurements of organ volume. These measurements indicated that intravascular pressure reduction caused vasodilation. However, these studies provided only indirect evidence for a myogenic mechanism in the blood vessels, and later investigators pointed out that alternative explanations were at least as plausible as a myogenic response.

Remark on “Algorithm 500: Minimization of Unconstrained Multivariate Functions [E4]”

Abstract: The subroutine incorporates two nonlinear optimization methods, a conjugate gradient algorithm and a variable metric algorithm, with the choice of method left to the user. The conjugate gradient algorithm is the Beale restarted memoryless variable metric algorithm documented in Shanno [7]. This method requires approximately 7n double-precision words of working storage to be provided by the user. The variable metric method is the BFGS algorithm with initial scaling documented in Shanno and Phua [10], and required approximately n2/2 + l l n /2 double-precision words of working storage. Whichever method is chosen, the same linear search technique is used for both methods, with two differences. The basic linear search uses Davidon's cubic interpolation to find a step length a, which satisfies

Mass spectrometric measurements of the neutral gas composition of the thermosphere and exosphere of Venus

Abstract: The neutral gas composition and density in the thermosphere of Venus is being measured with a quadrupole mass spectrometer on the Pioneer Venus orbiter. Data are obtained near periapsis once per day approximately 150-250 km above the surface. The principal gases in the thermosphere are CO2, CO, N2, O, N, and He. Atomic oxygen is the major constituent above 155 km on the dayside and also on the nightside up to 180 km when helium becomes the major constituent. The average values of CO2, CO, N2, O, and N remain nearly constant during day and night, but an abrupt change occurs across the terminator from a high dayside value to a low nightside value. The helium density varies in the opposite way, and a distinct bulge was observed at night near the morning terminator. The data have been used as the basis of an empirical model. Large orbit to orbit variations in densities were also observed on the nightside, suggesting perhaps strong turbulent motion in the atmosphere below. Kinetic temperatures inferred from scale heights are approximately 285 K on the dayside and 110 K at night. The average global temperature obtained from the model is 199 K.

Coefficients of relatedness in sociobiology

Abstract: A much-discussed, quantitative criterion for the spread of an altruistic gene is Hamilton's rule1,2c/b 0, the rule can be interpreted as requiring that the gene-caused action increase the ‘inclusive fitness’ of the actor. Since its introduction, Hamilton's rule and the attendant concept of inclusive fitness have gained increasing acceptance and use among biologists and have become integral in the field now named sociobiology. However, the essentially heuristic reasoning used in deriving these concepts, along with the lack of a complete specification even in the original outbred model2, have led to many investigations into the population genetical underpinnings of Hamilton's rule3–18. On the basis of these considerations, several reports3,10,12,13,18 have proposed new formulae for R. These formulae have no obvious relation to each other or to the coefficients originally suggested by Hamilton. This proliferation of coefficients is undoubtedly confusing to many and the net effect may be to generate distrust both of the rule and of the notion of inclusive fitness. Our purpose here is to show that these various formulae for R (refs 3,10,12,13,18), although independently derived, are actually the same.

Structural and functional diversity in 4-α-helical proteins

Abstract: Protein crystallographic studies show that many structural arrangements appear as common features among proteins which are otherwise unrelated in sequence or function. One of the more recently recognized recurring protein structural motifs is a nearly parallel arrangement of four α-helices to form a sequentially connected left-twisted bundle1. We describe here the geometrical properties of these structures and suggest how they relate to the functional and aggregate properties of these molecules.