Showing papers by "Brown University published in 1981"

The use of antiavidin antibody and avidin-biotin-peroxidase complex in immunoperoxidase technics.

Abstract: Avidin has an extraordinary affinity for the small-molecule vitamin biotin. Covalently coupling biotin or avidin to peroxidase molecules does not interfere with their normal biochemical functions. The avidin or biotin molecules, either peroxidase conjugated or unconjugated, can be brought to the antigen sites by means of an antiavidin antibody. Several immunohistochemical staining technics based on this principal have been described. The method utilizing an avidin-biotin-peroxidase complex was found to be more sensitive than the unlabeled antibody (PAP) method. This method involved four sequential staining procedures: (1) primary antibody (goat anti-human antigen); (2) secondary antibody (rabbit antigoat IgG) added in relative excess; (3) goat antiavidin antibody; (4) avidin-biotin-peroxidase complex. The applications of this technic are discussed.

A comparative study of the peroxidase-antiperoxidase method and an avidin-biotin complex method for studying polypeptide hormones with radioimmunoassay antibodies.

Abstract: A highly sensitive immunoenzymatic technic is presented. The method involves three sequential steps: (1) primary antibody, (2) biotin-labeled secondary antibody, and (3) avidin-biotin-peroxidase complex. Avidin, an egg white protein, has four binding sites for the low-molecular weight vitamin biotin. Many moieties of biotin can be coupled to the peroxidase molecule. Thus, since a relatively large amount of avidin is incubated with biotin-labeled peroxidase, avidin serves as a link between biotin-peroxidase molecules; in turn, biotin-peroxidase serves as a link between avidin molecules. Consequently, this large lattice-like complex with biotin-binding capability can be attracted to the sites of biotin-labeled antibody, producing a superior staining sensitivity. Several commercially available radioimmunoassay antibodies (e.g., antiglucagon, prolactin, gastrin, growth hormone, and thyroid-stimulating hormone antibodies) were tested for immunohistochemical staining. The unlabeled antibody peroxidase-antiperoxidase method fails to stain gastrin or thyroid-stimulating secretory cells when using these antibodies, and a relatively high antibody concentration is required to produce a positive reaction for glucagon, prolactin, and growth hormone. In contrast, the avidin-biotin-peroxidase complex method successfully demonstrates polypeptide hormones even when antibodies are diluted 20 to 40 times.

Infinite dimensional dynamical systems

Abstract: : An approach is outlined for the discussion of the qualitative theory of infinite dimensional dynamical systems. Retarded functional differential equations are used to illustrate the usefulness of the approach and the limitations of our present knowledge. (Author)

Ascent and eruption of basaltic magma on the earth and moon

Abstract: The ascent and emplacement of basaltic magma on the earth and moon is modeled by the application of geological and physical observations and constraints. Relatively simple mathematical models of the motion of gas/liquid mixtures are shown to be adequate in the treatment of basaltic eruptions, provided that allowance is made for the coalescence of gas bubbles and that realistic geological and petrochemical constraints are applied to the numerical values of variables. Because gas exsolution from magmas on the earth and moon commonly occur at depths of less than 2 km, it is generally convenient to consider separately the rise of bubble-free magmatic liquid at depth in a planetary crust and the more complex motions occurring near the surface with gas exsolution.

Existence and non-existence of global solutions for a semilinear heat equation

Abstract: The existence and non-existence of global solutions and theL p blow-up of non-global solutions to the initial value problemu′(t)=Δu(t)+u(t) γ onR n are studied. We consider onlyγ>1. In the casen(γ − 1)/2=1, we present a simple proof that there are no non-trivial global non-negative solutions. Ifn(γ−1)/2≦1, we show under mild technical restrictions that non-negativeL p solutions always blow-up inL p norm in finite time. In the casen(γ−1)/2>1, we give new sufficient conditions on the initial data which guarantee the existence of global solutions.

Tables of the Dynamic and Kinematic Viscosity of Aqueous KCl Solutions in the Temperature Range 25-150 C and the Pressure Range 0.1-35 MPa,

Abstract: Tabulated values of the dynamic and kinematic viscosity of aqueous sodium chloride solutions are given. The tables cover the temperature range 20–150 °C, the pressure range 0.1–35 MPa and is the concentration range 0–6 molal. It is estimated that the accuracy of the tabulated values is ±0.5%. The correlating equations from which the tables were generated are given.

Flow Localization in the Plane Strain Tensile Test

Abstract: The deformations in a plane strain tensile test are analyzed numerically, both for a solid characterized by a phenomenological corner theory of plasticity and for a nonlinear elastic solid As opposed to the simplest flow theory of plasticity with a smooth yield surface, both these material models exhibit shear band instabilities at a realistic level of strain Initial imperfections are specified in the form of thickness inhomogeneities A long-wavelength imperfection grows into the well-known necking mode and subsequently, at a sufficiently high local strain level, bands of intense shear deformations develop in the necking region The location of these shear bands is strongly influenced by the location of small strain concentrations near the surface, induced by various short-wave patterns of initial thickness imperfections In accord with the non-uniform straining in the neck it is found that the intensity of the localized deformations varies along the bands, and some of the shear bands end inside the material

Trypan blue dye uptake and lactate dehydrogenase in adult rat hepatocytes—Freshly isolated cells, cell suspensions, and primary monolayer cultures

Abstract: Leakage of lactate dehydrogenase and staining by the vital dye trypan blue were investigated in adult rat hepatocytes at the time of isolation, in suspensions up to 3 h and in primary monolayer cultures up to 3 d. These two parameters of plasma membrane integrity were found to correlate closely in hepatocyte suspensions, but to a lesser degree in monolayer cultures. Functional activity was demonstrated in culture by glucose consumption and lactic acid production. There was a balance of total lactate dehydrogenase (LDH) activity over time for both hepatocyte suspensions and cultures. Loss of LDH activity in the cell fraction was accompanied by a corresponding increase in enzyme activity in the media fraction. Lactate dehydrogenase activity per dye-excluding hepatocyte was calculated to be 9.2 +/- 1.5 X 10(-6) IU assayed at 37 degrees C for 25 preparations of isolated hepatocytes. The results suggest that leakage of cytoplasmic enzyme and vital dye staining are of comparable sensitivity in evaluating hepatocyte preparations. Measurement of LDH leakage offers a less subjective alternative to cell counting procedures and is applicable to both attached and suspended cells.

Tumor shedding and coagulation

Abstract: Three syngeneic carcinomas from two species shed plasma membrane vesicles when cultured in vitro or grown in the ascites tumor form in vivo. Shed vesicles carry procoagulant activity that can account for the activation of the clotting system and the fibrin deposition associated with these and many other types of malignancy in animals and man.

On the connectedness of degeneracy loci and special divisors

Abstract: Introduction Let C be a smooth complex projective curve of genus g, and let J be the Jacobian of C. Upon choosing a base-point in C, J may be identified with the set of linear equivalence classes of divisors of degree d on C. Denote by W~ the algebraic subvariety of J parametrizing divisors which move in a linear system of dimension at least r. A fundamental theorem of Kempf [9] and Kleiman and Laksov [11, 12] asserts tha t these loci are nonempty when their expected dimension

Predation pressure and gastropod foraging: a tropical-temperate comparison.

Abstract: Over the last two decades, theories of species diversity (Huston, 1979), antipredation phenomena (Vermeij, 1978) and reproductive effort (Cody, 1966) have involved a temperate-tropical gradient in predation. Comparative tropical-temperate observations in a number of systems support the case for an increase in predation intensity with a decrease in latitude (Cody, 1966; Bakus, 1974; Jeanne, 1979; Palmer, 1979); however, no experimental evidence has been presented. One of the stronger cases for a latitudinal gradient in predation pressure has been made for littoral gastropods (Vermeij, 1978, and included references). Intertidal gastropods are exposed to shellbreaking predation from two major feeding guilds: fishes and bottom-dwelling Crustacea (Vermeij, 1978; Palmer, 1979; Bertness and Cunningham, 1981). Crustaceans may either crush or peel prey shells. Small snails are generally crushed, while larger shells are grasped and pieces of apex or lip are chipped away until the molluscan soft parts are reached (Zipser and Vermeij, 1978; Bertness and Cunningham, 1981). Fish that feed on snails crush their prey and do not inflict the apical and aperture damage characteristic of crustacean related injury (Zipser and Vermeij, 1978; Palmer, 1979; Bertness, 1981). Birds are also known to feed on intertidal gastropods, but their overall effect seems minor (Gibb, 1956; Feare, 1971; Vermeij, 1978; Zach, 1978). 1 Present address: Smithsonian Tropical Research Institute, APO Miami, Florida 34002. Vermeij (1978) presented evidence indicating that the frequency of gastropod shell characteristics such as narrow or occluded apertures, low spires, thickened shells and strong shell sculpture increases from temperate to tropical seas. These morphological characteristics have been shown to defend gastropods from some kinds and sizes of predators (Vermeij, 1976, 1978; Zipser and Vermeij, 1978; Palmer, 1979; Bertness and Cunningham, 1981). In addition, tropical shell-crushing crabs are more efficient and specialized predators than their temperature equivalents (Shoup, 1968; Zipser and Vermeij, 1978). Palmer (1979) suggested that species of teleost fish and rays that crush gastropods are not only found more commonly in tropical oceans, but also are more specialized on a gastropod diet than their temperate relatives. Gastropod shell characteristics that appear to deter predation by fish are almost exclusively tropical in occurrence (Vermeij, 1978; Palmer, 1979). These lines of evidence strongly suggest that shell-crushing predation is greater on tropical than on temperate shells. The prevalence of shell-crushing predators in tropical waters has led to speculation and experimentation on the architectural defenses of gastropods against shell-crushing predators (Reynolds and Reynolds, 1977; Zipser and Vermeij, 1978; Palmer, 1979; Bertness and Cunningham, 1981). However, there have been no efforts to quantitatively compare the direct effects of crushing predation

The asymptotic stress and strain field near the tip of a growing crack under creep conditions

Abstract: The asymptotic stress and strain fields near the tip of a slowly growing crack are derived for elastic-nonlinear viscous materials, which deform in tension according to the law % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafuyTduMbai% aacqGH9aqpcuqHdpWCgaGaaiaac+cacaWGfbGaey4kaSIaamOqaiab% fo8aZnaaCaaaleqabaGaamOBaaaaaaa!428D!\[\dot \varepsilon = \dot \sigma /E + B\sigma ^n \]. The nonlinear viscous term describes power law creep. Based on (small strain) continuum mechanics, a stress analysis is carried out for anti-plane shear (Mode III), plane stress and plane strain (Mode I).

Moon: near-infrared spectral reflectance, a first good look.

Abstract: Spectral reflectance contains direct information on the mineralogy of the surface soils and rocks. A problem concerning the employment of remote spectral-reflectance sensing techniques for mineralogical studies is related to the lack of photometrically precise spectra of planetary surfaces in the region from 1.0 to 2.5 micrometers, where additional important mineral absorptions occur. Recently, a new instrument was developed, and an observational program is underway to provide the required near-infrared spectra. The first, comprehensive near-infrared spectroscopic results for the moon are presented. It is shown that it is equally possible to derive quantitative mineralogical information about the lunar surface by using remotely sensed reflectance spectra as it is by using laboratory reflectance measurements of lunar samples.

Depression and self-focused attention

Abstract: Recent research on self-focused attention has indicated effects that parallel several cognitive and affective phenomena associated with depression. Specifically, discrepancies between perceived real and ideal self, increased affective response, self-attribution for negative events, and accurate self-reports occur both in depression and as a result of self-focused attention. A study is reported that investigated the relationship between depression and a measure of private self-consciousness, a dispositional measure of the tendency to attend to one's inner thoughts and feelings. As predicted, a reliable positive relationship was found. The potential role of self-focused attention in maintaining and exacerbating depression was discussed.

The Sources of Political Tolerance: A Multivariate Analysis

Abstract: Over the past 25 years a number of conclusions concerning the development of political tolerance have come to be well accepted in the literature on political behavior. There are, however, two persisting problems with the studies that have generated these findings: they have relied on a content-biased measure of tolerance, and have failed to examine well specified models of the factors leading to tolerance. In this article we report the results of an analysis of the determinants of political tolerance using a content-controlled measure of tolerance and a more fully specified multivariate model. The parameters of the model are estimated from a national sample of the U.S. The results indicate the explanatory power of two political variables, the level of perceived threat and the commitment to general norms, and psychological sources of political tolerance. Social and demographic factors are found to have no direct effect and little indirect influence on the development of political tolerance.

Convenient and accurate discretized path integral methods for equilibrium quantum mechanical calculations

Abstract: In the path integral representation of quantum theory, a few body quantum problem becomes a classical many body problem. To exploit this isomorphism, it becomes necessary to develop methods by which degrees of freedom can be explicitly removed from consideration. The interactions among the remaining relevant variables are described by effective interactions. In this paper, we present a general methodology to carry out the reduction in numbers of degrees of freedom. Certain path integral algorithms are shown to correspond to reference systems for the full isomorphic classical many body problem. The correspondence allows one to determine systematic corrections to the algorithms by low order perturbation approximations familiar in the theory of simple classical fluids. We show how to use discretized path integrals to compute rigorous upper and lower bounds to the free energy for nontrivial quantum systems, and we discuss how to optimize the upper bounds with variational theories. Several illustrative example...

The influence of shell-type on hermit crab growth rate and clutch size (decapoda, anomura)

Abstract: [Les taux de croissance du Paguride Clibanarius albidigitus se sont reveles influences de facon significative par le type de coquille occupe. Le taux est le plus eleve pour les coquilles legeres et a volume interne important, et le plus bas pour les coquilles relativement lourdes, a volume interne faible. De meme, la dimension des pontes de C. albidigitus, Calcinus obscurus et Pagurus sp. (non decrit) est affectee de facon significative par le type de coquille. Chez les trois especes, la ponte est plus importante dans des coquilles legeres, a grand volume interne que dans les coquilles lourdes, a volume interne faible. Les observations sur les avantages resultant du choix de certaines coquilles, en ce qui concerne le taux de croissance et la dimension des pontes, montrent l'importance de ce choix et ses consequences dans le domaine de l'ecologie et de l'evolution de l'utilisation des coquilles par les Pagurides., Les taux de croissance du Paguride Clibanarius albidigitus se sont reveles influences de facon significative par le type de coquille occupe. Le taux est le plus eleve pour les coquilles legeres et a volume interne important, et le plus bas pour les coquilles relativement lourdes, a volume interne faible. De meme, la dimension des pontes de C. albidigitus, Calcinus obscurus et Pagurus sp. (non decrit) est affectee de facon significative par le type de coquille. Chez les trois especes, la ponte est plus importante dans des coquilles legeres, a grand volume interne que dans les coquilles lourdes, a volume interne faible. Les observations sur les avantages resultant du choix de certaines coquilles, en ce qui concerne le taux de croissance et la dimension des pontes, montrent l'importance de ce choix et ses consequences dans le domaine de l'ecologie et de l'evolution de l'utilisation des coquilles par les Pagurides.]

Gold Monetization and Gold Discipline

Abstract: Gold and its price have emerged as frequent topics of both academic and government debate.2 Public attention, focused on the gold market since gold’s price began fluctuating violently in 1980 and 1981, has turned to gold as a possible means of removing some discretion inherent in the current fiat money system. Since lack of adherence to monetary rules can lead to problems of dynamic policy inconsistency, academic economists have begun seriously to reconsider monetary standards based either on gold or on some other commodity as politically feasible methods of establishing rules.3

Lower bounds for VLSI

Abstract: Increased use of Very Large Scale Integration (VLSI) for the fabrication of digital circuits has led to increased interest in complexity results on the inherent VLSI difficulty of various problems. Lower bounds have been obtained for problems such as integer multiplication [1,2], matrix multiplication [7], sorting [8], and discrete Fourier transform [9], all within VLSI models similar to one originally developed by Thompson [8,9]. The lower bound results all pertain to a space-time trade-off measure that arises naturally within this model. In this paper, we extend the model and the class of functions for which non-trivial bounds can be proved. In Section 2, we give a more general model than has been proposed previously. In Section 3 we show how to reduce the derivation of lower bounds within the model to a problem in distributed computing In Section 4, we consider lower bounds for a number of predicates: n-input, l-output functions (as contrasted with the n-input, n-output functions which have been studied previously). In Section 5, we show that previous lower bound results (for n-input, n-output functions) also apply even when the model is extended to allow nondeterminism, randomness, and multiple arrivials. Finally, the full details of the results presented here will appear in the final version of this paper.