Showing papers by "University of Utah published in 1981"
TL;DR: Irradiation of 2,2-bis(2,4,6-trimethylphenyl)hexamethyltrisilane in hydrocarbon solution produces tetramesityldisilene, which can be isolated as a yellow-orange solid stable to room temperature and above in the absence of air.
Abstract: Irradiation of 2,2-bis(2,4,6-trimethylphenyl)hexamethyltrisilane in hydrocarbon solution produces tetramesityldisilene, which can be isolated as a yellow-orange solid stable to room temperature and above in the absence of air Like the olefins of carbon chemistry, tetramesityldisilene undergoes addition reactions across the silicon-silicon double bond
756 citations
01 Jan 1981
TL;DR: In this article, a brief summary of the quantum theory of angular momentum is given, which is at the core of the theory of magnetism, as the angular momentum of a charged particle is proportional to its magnetization.
Abstract: This chapter affords a brief summary of the quantum theory of angular momentum. As the angular momentum of a charged particle is proportional to its magnetization, this subject is at the core of the theory of magnetism. We shall show that motional angular momentum is inadequate, and introduce spin angular momentum. We shall develop operator techniques expressing angular momentum or spin operators in terms of more primitive fermion or boson operators. The topics of spin-one-half and spin-one are treated individually, for use in subsequent chapters on the theory of magnetism.
684 citations
TL;DR: A natural selection model for sex ratio control in a spatially variable environment and predictions of sex ratio alteration as a function of environmental change are tested in laboratory experiments with two parasitic wasps.
Abstract: We develop a natural selection model for sex ratio control in a spatially variable environment. Predictions of sex ratio alteration as a function of environmental change are tested in laboratory experiments with two parasitic wasps. Field data from a variety of other organisms also support the model. Finally, we discuss possibilities and difficulties for testing this type of evolutionary model.
663 citations
TL;DR: Neuronal types contributing to the inner plexiform layer of the cat retina are described based primarily on light microscopy of Golgi-impregnated retinal whole-mounts.
527 citations
TL;DR: In this paper, the ground state of a quantum mechanical antiferromagnetic model with next-nearest neighbor interactions was studied. But the results for the model were not exact.
Abstract: We present some exact results for the ground state of a quantum mechanical antiferromagnetic model in the two dimensions with next-nearest neighbor interactions.
509 citations
486 citations
350 citations
TL;DR: Pemoline was demonstrably more effective than placebo in a random-assignment, parallel, double-blind trial of placebo and pemoline, a noneuphorigenic psychostimulant drug effective in children with ADD.
Abstract: This study replicated an earlier one dealing with the diagnosis and treatment of attention deficit disorder (ADD, or minimal brain dysfunction) in adults. Subjects who met provisional operational criteria for adult ADD were entered in a random-assignment, parallel, double-blind trial of placebo and pemoline, a noneuphorigenic psychostimulant drug effective in children with ADD. There was improvement in both the pemoline group and the placebo group, but the difference in improvement was not statistically significant. When the analyses were confined to that subgroup of patients whose parents had described them in the 95th percentile of childhood "hyperactivity" or when the hyperactivity score was partialled out statistically, pemoline was demonstrably more effective than placebo. Revised operational criteria for adult ADD are proposed.
315 citations
TL;DR: Taxonomic theory can help students of cognition, evolutionary psychology, ethology, anatomy, and sociobiology to avoid serious mistakes, both practical and theoretical as mentioned in this paper, and it helps in generating hypotheses useful to a wide range of disciplines.
Abstract: Classifying is a fundamental operation in the acquisition of knowledge. Taxonomic theory can help students of cognition, evolutionary psychology, ethology, anatomy, and sociobiology to avoid serious mistakes, both practical and theoretical. More positively, it helps in generating hypotheses useful to a wide range of disciplines. Composite wholes, such as species and societies, are “individuals” in the logical sense, and should not be treated as if they were classes. A group of analogous features is a natural kind, but a group of homologous features is not. Imposing hypotheses justified only on the basis of nominalist, realist, phenomenalist, or conceptualist metaphysics upon the neurophysiology of organisms or upon the causes of behavior exemplifies the “psychologist's fallacy” of William James. Levels should be distinguished from their members and from classes of levels, and the ontological status of entities ranked at levels should be made clear. It is important not to confuse such categories as substance and process with one another. Several genetical terms, such as “gene” and chromosome,” are even more equivocal than has been realized. Discussions about units of selection, behavior, and thinking suffer from the ambiguity of a “unit of” an entity. An important source of misunderstanding about natural selection is the habit of treating it as an “agent”: in an important sense, natural selection does not “act” at all.
276 citations
TL;DR: The results favor the view that some AFP synthesis still exists after birth; however, the rate of synthesis may also decrease with age, and the wide range of variation in serum AFP levels in infants of various ages indicates that there must be more than one unknown factor affecting the AFP serum level.
Abstract: Serum alpha-fetoprotein (AFP) levels were monitored in 32 normal babies consecutively from 2 to 3 days, 2 wk, and 2 and 4 months after birth. In addition, serum AFP concentration was also measured in 116 random specimens from infants with normal liver enzymes and 10 infants born immaturely. Results were combined to establish normal AFP levels for infants at various ages. Serum AFP disappeared rapidly after birth. We found that it was not until 8 months of age that the normal AFP level in infants approached adult level. The half-lives of AFP degradation were estimated to be 5.5 days between birth and 2 wk, 11 days between 2 wk to 2 months, and 33 days between 2 and 4 months of age. In contrast to earlier belief, we felt that some AFP synthesis still exists after birth; however, the rate of synthesis may also decrease with age.
275 citations
TL;DR: A survey of data from tropical and temperate regions confirms that nectars of hummingbird and honeyeater flowers are dilute, especially relative to nectar of bee flowers as mentioned in this paper.
Abstract: A survey of data from tropical and temperate regions confirms that nectars of hummingbird and honeyeater flowers are dilute, especially relative to nectars of bee flowers. We use these data, along with theoretical considerations, to examine three recently proposed hypotheses to explain low concentration of hummingbird nectars. None of the quantitative or qualitative predictions of these three hypotheses appears to be upheld. We discuss possible weaknesses of each hypothesis and then present a general framework which may be useful in generating new hypotheses to explain the evolution of nectar concentration. OVER THE PAST FEW YEARS, several authors have discussed sugar concentration of nectars from flowers attracting different kinds of pollinators (e.g., Percival 1965, 1974; Watt et al. 1974; Baker 1975, 1977; Hainsworth and Wolf 1976). One interesting observation is that nectars of hummingbird and honeyeater flowers are dilute, especially relative to nectars of bee flowers (e.g., Hainsworth and Wolf 1972b, 1976; Hainsworth 1973; Stiles 1975; Baker 1975; Percival 1965; Pyke 1979b). Nectar concentrations of 202 plant species known or presumed on morphological grounds to be largely hummingbird-pollinated average 25.4 percent sucrose-equivalent sugars weight by total volume (equals about 23.2% weight by total weight; table 1). Concentrations of 47 honeyeaterpollinated species are similar and average 23.4 percent wt/vol (equals about 21.6% wt/wt; table 2). In contrast, concentrations of 156 largely bee-pollinated species average 41.6 percent (equals about 36.0% wt/wt; table 3). For conversion from percent wt/vol to percent wt/wt see Hodgman et al. (1956: 1925) and Bolten et al. (1979). The most detailed discussions of dilute hummingbird nectars are those of Baker (1975), Calder (1979), and Bolten and Feinsinger (1978). Baker (1975) suggests (p. 39) that "the high energy needs ... [of hummingbirds] will select for richness in energy-giving sugars in the nectars that they favor." He adds (p. 39) that "Increase in sugar concentration necessarily means an increase in the viscosity of the nectar, which could be disadvantageous to a bird that must hover in front of flowers while drinking . (emphasis ours), and that as a result (p. 40) ". tPresent address: The Australian Museum, Sydney, N.S.W. 2000, Australia. 2Present address: Department of Biology, University of California, Riverside, California 92521, U.S.A. a compromise between higher sugar concentration (with smaller volume) and lower concentration (requiring a larger volume for the same caloric content) will be reached in the nectars of hummingbird flowers." Baker also points out (p. 39) that viscosity of a sugar solution increases rapidly above concentrations of about 20 percent (the relationship is exponential, cf. Hodgman et al. 1956: 2042), and implies, we believe, that for these reasons (p. 40) the ". . compromise appears to be struck very often at about 20 to 25 percent [wt/wt; equals about 22 to 28% wt/voll sucrose equivalent." Hence Baker appears to suggest that sugar concentrations of hummingbird flowers have evolved to maximize net rates of energy intake by foraging birds. Baker (1975: 40) also suggests that "Another factor which may limit the strength of hummingbird nectars is the need that these birds have for free water as well as energy-giving sugar for life support." This second hypothesis is pursued by Calder (1979), who suggests (p. 185) that ". . . flowers which have coevolved with pollination by hummingbirds could provide both energy and water balance simultaneously if they produced nectars of appropriate concentrations which depend on environmental temperature," and further (p. 186) that "Since the temperatures to which hummingbirds are exposed range from cold to hot, and the water balance problems range from excess to scarcity, one might look for . . . an in'verse relationship betweenz temperature and optimal nectar concentrationi" (emphasis ours). Calder presents data which (p. 192) ". . . tend to suggest a trend in which concentration may be inversely related to temperature, but the ranges overlap considerably." Bolten and Feinsinger ( 1978) propose a third hypothesis. They suggest (p. 307) that ". . . low sugar concentrations in many hummingbird-pollin260 BIOTROPICA 13(4): 260-27
TL;DR: In this article, the long-term development of social bonds, including their growth and deterioration, their interaction processes that occur over the history of social relationships, and their holistic systems like qualities, are examined in the chapter.
Abstract: Publisher Summary The long-term development of social bonds, including their growth and deterioration, their interaction processes that occur over the history of social relationships, and their holistic systems like qualities, are examined in the chapter. The chapter integrates and extends the social penetration theory and the privacy regulation theory. It introduces the study of interpersonal relationships. The chapter compares social penetration and privacy regulation frameworks in terms of their similarities and differences and their strengths and weaknesses. It examines the concept of dialectics from a historical and philosophical perspective and describes a particular dialectic approach. The idea of opposition, the unity of opposites, and the concept of change are discussed under the concept of dialectics. Then the chapter explores assumptions about social relationships, wherein it discusses about general philosophical assumptions, homeostasis and the maintenance of stability, and specific assumptions about openness-closeness and stability-change. The chapter discusses research conducted on openness-closeness and stability-change processes in reference to (1) relationship development, (2) crises in social relationships, (3) intimacy of exchange, (4) personal characteristics of interaction style, and (5) the interpersonal unit-matching and timing of interaction.
TL;DR: There are in fact three major criteria dividing six phenomona, rather than a single dichotomy between mimicry and crypsis, and each author's definition includes differing and partially overlapping subsets of the six classes:crypsis; masquerade; Batesism; Mullerism; polymorphism and convergence.
Abstract: There have been many different and conflicting definitions of mimicry. Some of the definitions of mimicry include crypsis and others do not. Each definition includes different groups of phenomena and uses different criteria to distinguish mimetic from non-mimetic phenomena. The confusion is eliminated by a consideration of the criteria of all definitions. This shows that there are in fact three major criteria dividing six phenomona, rather than a single dichotomy between mimicry and crypsis (Table 2). The criteria are defined by the results of a mistake in discrimination between the model and mimic: (a) the mistake does or does not depend upon relationship between mimic and background; (b) the mistake has or has no effect on the population dynamics or evolution of the model and (c) the mistake affects dynamics or evolution of one or of many models. The main reason for the contusion about mimicry and crypsis is that each author's definition includes differing and partially overlapping subsets of the six classes: crypsis; masquerade; Batesism; Mullerism; polymorphism and convergence.
TL;DR: Three homologous toxic peptides which cause postsynaptic inhibition at the vertebrate neuromuscular junction have been purified from the venom of the marine snail Conus geographus.
TL;DR: In this paper, the authors studied the excitation spectrum of an antiferromagnetic chain exhibiting the effects of both dimerization and frustration, based on an exact solution for the doubly degenerate ground state, and viewed the excitations as propagating defect boundaries between the two exact ground states.
Abstract: The excitation spectrum of an antiferromagnetic chain exhibiting the effects of both dimerization and frustration is studied. The method used is based on an exact solution for the doubly degenerate ground state, and views the excitations as propagating defect boundaries between the two exact ground states. These excitations are analogous to "solitons," and can bind into a second type of excitation, analogous to "breathers."
TL;DR: In this paper, the authors evaluated solid and liquid phase gastric emptying using 99mTc-sulfur colloid-labeled chicken liver and DTPA, and emptying was quantitated using the geometric mean of the anterior and posterior counts.
Abstract: Ten subjects were given self-selected filling meals (mean weight = 1692 g) and meals of 900 and 300 g. The three meals varied in composition and total kcal. Solid and liquid phase gastric emptying was evaluated using 99mTc-sulfur colloid-labeled chicken liver and [111In]DTPA, and emptying was quantitated using the geometric mean of the anterior and posterior counts. Emptying of the solid-phase marker was linear; mean half-emptying times were 277 min, 146 min, and 77 min for the filling, 900-g, and 300-g meals, respectively. Emptying of the liquid-phase marker was curvilinear, mean half-emptying times were 178 min, 81 min, and 40 min, for the filling, 900-g, and 300-g meals, respectively. Thus, meals of larger weight and kcal content were associated with longer emptying times for both solids and liquids.
TL;DR: The nucleus is the site where cellular capped RNAs prime viral RNA transcription and donate their 5′ caps and about 10 to 13 nucleotides to the viral mRNAs; and essentially only those capped cellular RNAs synthesized after infection, and not those synthesized before infection, are used as primers.
TL;DR: Two predictions of this model, namely, that the requirement of continuous protein synthesis for genome replication is not at the level of the initiation of the genome chains but at thelevel of the suppression of the leader RNA termination signal, have been tested experimentally and the results found to be consistent with the above model.
TL;DR: In this article, a 3D volume integral equation algorithm was adapted to magnetotelluric (MT) modeling, where the two symmetry planes of a buried prismatic body and a normally incident plane wave source were used to reduce the computation time and storage.
Abstract: We have adapted a three‐dimensional (3-D) volume integral equation algorithm to magnetotelluric (MT) modeling. Incorporating an integro‐difference scheme increases accuracy somewhat. Utilizing the two symmetry planes of a buried prismatic body and a normally incident plane wave source greatly reduces required computation time and storage. Convergence checks and comparisons with one‐dimensional (1-D) and two‐dimensional (2-D) models indicate that our results are valid. We show theoretical surface anomalies due to a 3-D prismatic conductive body buried in a half‐space earth. Instead of studying the electric and magnetic fields, we have obtained impedance tensor and magnetic transfer functions by imposing two different source polarizations. Manipulation of the impedance tensor and magnetic transfer functions yields the following MT quantities: apparent resistivity and phase, impedance polar diagrams, tipper direction and magnitude, principal directions, skew, and ellipticity. With our preliminary analyses of...
TL;DR: Shrubs are shown to have the widest range of absorptance, with perennial herbs and cacti exhibiting a smaller range, and very little variation in leaf absorptances among trees and annuals.
Abstract: Leaf absorptances to solar radiation in the 400-700 nm (photosynthetically useful wavelengths) are presented for a diversity of species in the Mohave and Sonoran Deserts of North America. As a life form shrubs are shown to have the widest range of absorptance, with perennial herbs and cacti exhibiting a smaller range, and very little variation in leaf absorptances among trees and annuals. The measurement of leaf absorptance at 625 nm is shown to be the same as the leaf absorptance to solar radiation over the 400-700 nm. Over a wide range of species and absorptances, the total solar leaf absorptance (400-3,000 nm) is shown to be closely related to the 400-700 nm leaf absorptance.
TL;DR: Children receiving coping plus modeling techniques were more calm and cooperative during invasive procedures than children receiving coping or modeling alone and other measures indicated that the coping procedures were more effective than modeling only procedures for both parents and children.
TL;DR: Results suggest that 12independent waveforms, derived from the 192 measured ECGs, may be used in place of those ECGs in theKarhunen-Loeve technique of random process representation as 97 patients with independently documented heart disease were used in the study.
Abstract: The Karhunen-Loeve technique of random process representation was investigated as a method of quantitatively characterizing body surface potential maps. One hundred ninety-two lead body surface potential maps from 124 normal subjects and 97 patients with independently documented heart disease were used in the study. Each map frame in QRS and ST-T of 34 maps in a test set was represented as a linear sum of orthonormal distributions derived from the covariance matrix estimated from all QRS frames in the 221 training maps. A 16:1 reduction in spatial data of the test set was achieved with rms errors of 45 and 21 microV in QRS and ST-T, respectively. Results suggest that 12 independent waveforms, derived from the 192 measured ECGs, may be used in place of those 192 ECGs. In addition to providing a convenient and familiar method of display for map data, the technique puts the data in an appropriate form for quantitative statistical analysis.
TL;DR: The data suggest that clinical expression of experimental collagen-induced arthritis and immune responsiveness to type II collagen are controlled in part by genes within or closely linked to the rat major histocompatibility complex--RT1.
Abstract: Seven inbred rat strains were tested for susceptibility to experimental type II collagen-induced arthritis and for development of cellular immunity to type II collagen by delayed hypersensitivity skin testing. WF (RT1u), LEW (RT1l), and DA (RT1a) were the most susceptible of the strains tested with respect to incidence (greater than 95%) and severity of disease. LEW and DA were strongly skin test reactive to calf type II collagen. BUF (RT1b) developed moderate skin test responses to calf type II collagen and showed low susceptibility to collagen arthritis (1/8). MAXX (RT1n), LEW.B3 (RT1nvl), and AUG (RT1c) were not susceptible to collagen arthritis and showed negative to very weak skin test responses to type II collagen. Disease susceptibility was inherited as a dominant trait in the F1 progeny of (WF X LEW.B3) matings. These data suggest that clinical expression of experimental collagen-induced arthritis and immune responsiveness to type II collagen are controlled in part by genes within or closely linked to the rat major histocompatibility complex--RT1.
TL;DR: Several common plants (Chenopodiaceae) of the Australian arid zone produce diaspores that bear small and inconspicuous food bodies and are adapted for dispersal by ants, suggesting an adaptation for highly directional dispersal of diaspore to favorable microsites where nutrients are concentrated and possibly more accessible.
Abstract: Several common plants (Chenopodiaceae) of the Australian arid zone produce diaspores that bear small and inconspicuous food bodies and are adapted for dispersal by ants. For these species, myrmecochory probably represents an adaptation for highly directional dispersal of diaspores to favorable microsites where nutrients are concentrated and possibly more accessible. Dispersal of diaspores by ants can have a pronounced effect on plant dispersion. In habitats characterized by red, crusty alluvial loam soils, myrmecochorous species grow almost exclusively on ant mounds; these same species grow in relatively continuous stands in sandy soil habitats. The flora of the Australia arid zone may contain many plant species that are adapted to use ants as dispersal agents. We consider several factors that may have promoted or facilitated the evolution of myrmecochory in arid zone plants.
TL;DR: Genetic and biochemical analyses of lambda groE+ transducing phages and their deletion and point mutant derivatives show that the groE locus consists of two closely linked genes that cause similar phenotypes, with respect to lambda phage head morphogenesis and bacterial growth at nonpermissive temperatures.
Abstract: Previous work has uncovered the existence of an Escherichia coli locus, groE, that is essential for bacterial growth, lambda phage and T4 phage head morphogenesis, and T5 phage tail assembly. Our genetic and biochemical analyses of lambda groE+ transducing phages and their deletion and point mutant derivatives show that the groE locus consists of two closely linked genes. One groE gene, groEL, has been shown to encode the synthesis of a 65,000 Mr polypeptide, whereas the second, groES, codes for the synthesis of a 15,000 Mr polypeptide. About half of the groE- bacterial isolates fall into the groES complementation group. GroE mutations in either gene cause similar phenotypes, with respect to lambda phage head morphogenesis and bacterial growth at nonpermissive temperatures.
TL;DR: It is suggested that behavioral ecologists expend more effort on simple, plausible models of animal behavior, which provide ready-made testable hypotheses about the animal's approximation to optimality and about the actual mechanisms of behavior.
Abstract: Summary. We consider models of behavior that apply to two different problems: when a predator should leave a foraging site and how a female should choose the best available male. In each case we derive rules for an optimal solution to the problem. We also derive models based on very simple, plausible rules of behavior that we suspect animals may actually use. Although the expected payoffs from optimality models always exceed the expected payoffs from our simpler behavioral models, under certain conditions the difference is not large. When good foraging sites last but a short time and when females' mobility in their habitat is limited, the results of simple models and optimal models are very close indeed. Because of the difficulty of distinguishing between the results of each type of model and because natural selection will presumably provide a best mix of solutions to a range of problems rather than a best solution to any one problem, we suggest that behavioral ecologists expend more effort on simple, plausible models of animal behavior. Such models provide ready-made testable hypotheses about the animal's approximation to optimality and about the actual mechanisms of behavior.
TL;DR: It is demonstrated that the presence of 6-methoxybenzoxazolinone in the plant food resource acts as the ultimate cue to trigger reproductive effort in Microtus montanus.
Abstract: In a replicated experiment, nonbreeding winter populations of Microtus montanus were given supplements of rolled oats coated with 6-methoxybenzoxazolinone, a naturally occurring plant derivative. After 3 weeks of this feeding regime, samples from the populations demonstrated a high incidence of pregnancy in females and testicular hypertrophy in males. Control populations receiving rolled oats coated only with the solvent showed no reproductive activity. These results demonstrate that the presence of 6-methoxybenzoxazolinone in the plant food resource acts as the ultimate cue to trigger reproductive effort in Microtus montanus.
TL;DR: This paper derives specific predictions from three alternative hypotheses which deal with mode of fertilization (internal versus external) and parental care evolution, and test these predictions using a compilation of published data on occurrence and correlates of parental care in amphibians and teleost fishes.
Abstract: Why is parental care performed by the female in some species and the male in others? Several answers have been proposed by theoretical studies (Trivers, 1972; Williams, 1975; Dawkins and Carlisle, 1976; Maynard Smith, 1977, 1978; Perrone and Zaret, 1979), but there have been few efforts to test alternative hypotheses against observed patterns of vertebrate parental behavior. The present paper attempts to (1) derive specific predictions from three alternative hypotheses which deal with mode of fertilization (internal versus external) and parental care evolution, and (2) test these predictions using a compilation of published data on occurrence and correlates of parental care in amphibians and teleost fishes. In a recent review of species with male parental care, Ridley (1978) concluded: "The data implicate the mode of fertilization as the most important variable determining which parent is selected to care. Parental care usually correlates with external fertilization. There exists two hypotheses to explain this: certainty of paternity and order of gamete release. It is likely that each is the final (evolutionary) cause in different phylogenetic lineages." The "certainty of paternity" hypothesis stems from the assumption that a male is unlikely to care for offspring if those offspring are not his own genetic progeny (Alexander, 1974). Trivers (1972) hypothesized that reliability of paternity will be affected by mode of fertilization-since external fertilization is without oviposition delay, reliability of paternity may be greater than with internal fertilization.