Showing papers by "University of Rochester published in 1974"
994 citations
TL;DR: A new method of assigning patients to treatment and control groups to minimize differences between the groups, not only in the number of patients but in patient characteristics is described, demonstrating a four‐ to fivefold reduction of the probability of severe imbalance, relative to randomization.
Abstract: This paper describes a new method of assigning patients to treatment and control groups to minimize differences between the groups, not only in the number of patients but in patient characteristics. Testing the method by computer simulations, using data on 40 patients with 15 variates each, demonstrates a four- to fivefold reduction of the probability of severe imbalance, relative to randomization. Minimization can maintain tight control of one variate, comparable to the currently acceptable experimental design of blocking, while reduCing the probability of severe imbalance in the other 14 variates by a factor of 3. It also compares favorably with accepted methods regarding susceptibility to experimenter bias. Therefore, it is suggested that minimization should replace randomization in assigning patients in clinical trials.
762 citations
TL;DR: In this paper, the authors deal with questionnaires tapping fears of snakes, spiders, mutilation, and public speaking, and find consistent distribution characteristics of the scales across several samples.
728 citations
TL;DR: Findings support the view that outcome is not a single process but is comprised of several semi-independent processes best conceptualized as open-linked systems and must be considered in understanding, evaluating, and treating the different areas of outcome disability in schizophrenia.
Abstract: This report describes the characteristics of outcome and its predictors in a cohort of patients evaluated in the Washington Center of the International Pilot Study of Schizophrenia. Part I, focusing on the characteristics of outcome, suggested that outcome consists of several semi-independent processes. This second part focuses on the nature of predictor-outcome relationships in this cohort of patients. Results demonstrate that employment function and social relations in the past were each the best predictor of its respective outcome function. Established chronicity of illness predicted outcome in all areas. The findings support the view that outcome is not a single process but is comprised of several semi-independent processes best conceptualized as open-linked systems. Each system must be considered in understanding, evaluating, and treating the different areas of outcome disability in schizophrenia.
619 citations
564 citations
TL;DR: In this article, an explicit form for the Lagrangian of an arbitrary-spin boson field was obtained by introducing auxiliary field variables which are required to vanish in the free-field limit.
Abstract: An explicit form is obtained for the Lagrangian of an arbitrary-spin boson field. This is achieved by introducing auxiliary field variables which are required to vanish in the free-field limit. For $s\ensuremath{\le}4$ the results are found to be in agreement with those obtained by Chang. Canonical commutation rules are derived and the equations of motion are brought to first-order form, thereby facilitating the introduction of minimal electromagnetic coupling. It is found that, upon taking the Galilean limit, the ($6s+1$)-component Galilean-invariant theory of Hagen and Hurley results. The $g$ factor is found to be $\frac{1}{s}$, thereby confirming a long-standing conjecture.
382 citations
TL;DR: Clinical and laboratory evaluation of 15 infant-mother pairs exposed to methylmercury during pregnancy, including mercury determinations in blood samples of mothers and infants, and in milk samples from mothers, during the first seven months following the epidemic.
Abstract: A disastrous epidemic of methylmercury poisoning occurred in rural Iraq early in 1972, due to the ingestion of home-made bread prepared from wheat treated with a methylmercury fungicide. We report the clinical and laboratory evaluation of 15 infant-mother pairs exposed to methylmercury during pregnancy, including mercury determinations in blood samples of mothers and infants, and in milk samples from mothers, during the first seven months following the epidemic.
359 citations
TL;DR: The continuous-time random walk of Montroll and Weiss has a complete separation of time (how long a walker will remain at a site) and space (how far a walkers will jump when it leaves a site). The time part is completely described by a pausing time distributionψ(t) as mentioned in this paper.
Abstract: The continuous-time random walk of Montroll and Weiss has a complete separation of time (how long a walker will remain at a site) and space (how far a walker will jump when it leaves a site). The time part is completely described by a pausing time distributionψ(t). This paper relates the asymptotic time behavior of the probability of being at sitel at timet to the asymptotic behavior ofψ(t). Two classes of behavior are discussed in detail. The first is the familiar Gaussian diffusion packet which occurs, in general, when at least the first two moments ofψ(t) exist; the other occurs whenψ(t) falls off so slowly that all of its moments are infinite. Other types of possible behavior are mentioned. The relationship of this work to solutions of a generalized master equation and to transient photocurrents in certain amorphous semiconductors and organic materials is discussed.
353 citations
TL;DR: In the last few years the picture of the ionic channels has grown considerably more tangible, though it still falls far short of a detailed molecular description, and this article describes this sharpened picture and reviews the evidence for it.
Abstract: The current phase of axon physiology began with the invention of the voltage clamp by Cole (1949) and its use by Hodgkin & Huxley (1952d) to produce an astonishingly complete analysis of the ionic permeabilities that are responsible for the action potential. Their description did notcontain much in the way of molecular detail, and left open such questions as whether ions cross the membrane by way of pores or carriers, and the nature of the ‘gating‘ processes that increase ordecrease ion permeability in response to changes of the membrane potential. In the last few years our picture of the ionicchannels has grown considerably more tangible, though it still falls far short of a detailed molecular description. This article describes this sharpened picture and reviews the evidence for it. The viewpoint expressed is a very personal one, andno attempt has been made to review the literature of axonology comprehensively.
338 citations
TL;DR: The ultrastructure of osteoclasts was examined in fetal rat bones after stimulation or inhibition of resorption in culture, suggesting that the cells had returned to their inactive state.
Abstract: The ultrastructure of osteoclasts was examined in fetal rat bones after stimulation or inhibition of resorption in culture. A central ruffled border area completely encircled by a clear zone was considered to represent the resorbing system of the cell. The proportion of ruffled border and clear zone in osteoclast cross sections was compared with changes in bone resorption as measured by the release of previously incorporated radioactive calcium (45Ca). In control cultures 55% of the osteoclast cross sections showed an area closely apposed to bone and this consisted mainly of clear zone; only 11% showed ruffled borders. Treatment with parathyroid hormone (PTH) increased 45Ca release, increased the frequency of finding areas closely apposed to bone (79%), and markedly increased the frequency of the ruffled border area (64%). Colchicine given concurrently with PTH decreased the number of osteoclasts. Colchicine or calcitonin treatment after PTH stimulation decreased the proportion of ruffled border area significantly by 1 h; this was followed by a decrease in 45Ca release. These inhibited osteoclasts resembled osteoclasts from control, unstimulated cultures, suggesting that the cells had returned to their inactive state. Colchicine-treated osteoclasts also showed a loss of microtubules and a massive accumulation of 100 A filaments, suggesting that synthesis of microtubular subunits had increased.
328 citations
TL;DR: In this article, the production equations of Steele, of Vollenweider, and of Fee are transformed to meet this requirement, by choosing the quantum yield of photosynthesis in weak light as parameter instead of the maximum rate in saturating light.
Abstract: For eventual incorporation into a general theory of phytoplankton dynamics, an equation for gross daily production in a water column is needed which is an explicit function of phytoplankton concentration and which does not contain parameters or coefficients dependent on phytoplankton concentration: the production equations of Steele, of Vollenweider, and of Fee are transformed to meet this requirement. It is also desirable, in order to simplify theoretical analysis, that the parameters in production equations be chosen so as to minimize the range of values needed to describe the variation of photosynthesis in nature. This can be achieved by choosing the quantum yield of photosynthesis in weak light as parameter instead of the maximum rate in saturating light. In lakes, the value of the quantum yield in weak light is likely to be about 0.06 moles carbon per einstein absorbed. An additional advantage of the transformed equations is to make evident a simple relation between actual daily production and the upper limit to production.
TL;DR: It is demonstrated that genetically "nonresponsive" mice have the structural and regulatory genes necessary for expression of these inducible microsomal monooxygenase activities and associated new formation of cytochrome P1-450 and that the defect in these mice is a failure to recognize aromatic hydrocarbons which are less potent inducers.
TL;DR: One of the main branches of the left main coronary artery of normally beating dog hearts was perfused with a silicone elastomer which solidified within the vasculature, providing a basis mainly for concurrent flow in neighboring capillaries, and for some diffusional exchange between inflow and outflow regions.
Journal Article•
TL;DR: The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the induction of microsomal oxygenase were studied in the rat and had little effect on hepatic aminopyrine N-demethylase and NADPH-cytochrome c reductase.
Abstract: The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the induction of microsomal oxygenase were studied in the rat. TCDD was 3 x 104 times more potent than 3-methylcholanthrene (MC) as an inducer of hepatic aryl hydrocarbon hydroxylase. Half-maximal induction occurred at a dose of 0.85 nmole/kg. TCDD and MC produced parallel log dose-response curves for the induction of hepatic aryl hydrocarbon hydroxylase, with the same maximal response. The simultaneous administration of maximally inducing doses of both drugs produced no greater response than either drug alone. TCDD, like MC, induced a spectrally distinct type of cytochrome P-450, with a shift in the absorption maximum of the carbon monoxide difference spectrum from 450 nm to 448 nm, and an increase in the ratio of the 455 nm:430 nm absorption maxima of the ethyl isocyanide difference spectra. Following a single dose of TCDD (31.1 nmoles/kg), hepatic aryl hydrocarbon hydroxylase activity and microsomal hemoprotein remained elevated for over 35 days. Both TCDD and MC had little effect on hepatic aminopyrine N-demethylase and NADPH-cytochrome c reductase. The dose of TCDD which produced half-maximal induction of hepatic aryl hydrocabon hydroxylase in the rat, chick embryo, and several strains of mice was similar, varying from 0.4 to 1.2 nmoles/kg.
TL;DR: The inviscid stability of swirling flows with mean velocity profiles similar to that obtained by Batchelor (1964) for a trailing vortex from an aircraft is studied with respect to infinitesimal non-axisymmetric disturbances as discussed by the authors.
Abstract: The inviscid stability of swirling flows with mean velocity profiles similar to that obtained by Batchelor (1964) for a trailing vortex from an aircraft is studied with respect to infinitesimal non-axisymmetric disturbances. The flow is characterized by a swirl parameter q involving the ratio of the magnitude of the maximum swirl velocity to that of the maximum axial velocity. It is found that, as the swirl is continuously increased from zero, the disturbances die out quickly for a small value of q if n = 1 (n is the azimuthal wavenumber of the Fourier disturbance of type exp{i(αx + nϕ − αct)}); but for negative values of n, the amplification rate increases and then decreases, falling to negative values at q slightly greater than 1·5 for n = −1. The maximum amplification rate increases for increasingly negative n up to n = −6 (the highest mode investigated), and corresponds to q ≃ 0·85. The applicability of these results to attempts at destabilizing vortices is briefly discussed.
TL;DR: In this paper, a simple improvement on the usual on-shell approximation (which in the single-atom case is part of the Weisskopf-Wigner approximation) yields new solutions for the various probability amplitudes in the form of infinite series involving all the retardation times.
Abstract: The problem considered is that of two identical two-level atoms a fixed distance $r$ apart, one of which is excited at $t=0$. A simple improvement on the usual on-shell approximation (which in the single-atom case is part of the Weisskopf-Wigner approximation) yields new solutions for the various probability amplitudes in the form of infinite series involving all the retardation times $\frac{\mathrm{nr}}{c}$. The truncated solutions involving only the single retardation time $\frac{r}{c}$ are compared with previously published results both when all photon modes are allowed and when only photons propagating along the interatomic axis are allowed. When the retardation times are neglected, the series are summed to give the well-known results of Stephen and others.
TL;DR: In this article, a theory of the time dependence of resonance transfer of excitation energy between molecules is developed in terms of memory functions appearing in the transition rates of a generalized master equation (GME).
Abstract: A theory of the time dependence of resonance transfer of excitation energy between molecules is developed in terms of memory functions appearing in the transition rates of a generalized master equation (GME). The memory can be computed explicitly and, due to the coarse-graining operation incorporated in our derivation of the GME, the accuracy of the memory function depends only on the amount of detailed information one has, or wishes to include, about the spectrum and dynamics of the system. The formalism yields a unified description of coherent motion at short times and diffusive transport at long times, and for the case of transfer between and among identical molecules provides a generalized approach to the theory of exciton transport. Memory functions for transfer between anthracene molecules are obtained as an illustration of the theory. The connection between the new formalism and existing exciton-transport theories is indicated and its relation to the theory of non-Markoffian random walks is presented.
TL;DR: In this paper, the effect of the cubic term was studied using perturbation theory, and all the details of the observed spectra were reproduced, and the eigenvalue problem was reduced to simple radial Hamiltonians which are explicitly given for the most important acceptor states.
Abstract: In a previous paper the effective-mass Hamiltonian for shallow acceptor states was separated into a spherical term and a cubic contribution. Neglecting the latter term, a spherical model was formulated which explained the main features of the experimental acceptor spectra. Here the effects of the cubic term are studied using perturbation theory, and all the details of the observed spectra are reproduced. As in the case of the spherical model, the eigenvalue problem is reduced to simple radial Hamiltonians which are explicitly given for the most important acceptor states. These Hamiltonians are solved numerically and the resulting eigenvalues are tabulated as functions of the relevant parameters. The predicted spectra are in good agreement with available experimental data for acceptors in Ge, InSb, and GaAs, but not for acceptors in Si, where the unusual strength of the cubic term makes the present analysis unsatisfactory.
TL;DR: The results suggest that local PGE2 production may contribute to the inflammatory changes and bone resorption seen in periodontal disease.
Patent•
09 Aug 1974TL;DR: In this paper, a surgical implant is produced by coating a metallic substrate with enamel, which provides chemical stability, resistance to wear, tissue compatibility, progressive ingrowth and electrical insulating properties.
Abstract: A surgical implant is produced by coating a metallic substrate with enamel. The metallic substrate provides structural strength and the enamel provides chemical stability, resistance to wear, tissue compatibility, progressive ingrowth and electrical insulating properties. The implant may be produced by coating a portion of the metallic substrate with a partially crystallized enamel, and then positioning the implant on a firing support with the partially crystallized enamel in contact with the support and coating the remaining non-enamelled surface.
TL;DR: This technique was shown to restore normal valve function with predictable and stable long-term results, and 96 per cent of acquired tricuspid valve disease can be managed by this technique.
TL;DR: In this article, a retrospective analysis of the course of 125 patients in whom flow-directed balloon-tipped catheters were employed showed that pulmonary ischemic lesions appeared to have occurred as a direct result of the use of the catheter.
Abstract: Retrospective analysis of the course of 125 patients in whom flow-directed balloon-tipped catheters were employed showed that in nine (7.2 per cent), pulmonary ischemic lesions appeared to have occurred as a direct result of the use of the catheter. Mechanisms of the pulmonary ischemia included persistent wedging of the catheter tip in a peripheral artery (six cases), obstruction of a more central pulmonary artery by an inflated balloon (one case), and pulmonary embolism from venous thrombosis developing around the catheter (two cases). Awareness of the tendency for spontaneous wedging of the catheter to occur and of the possibility of air remaining in the balloon after use should reduce the frequency of these complications. (N Engl J Med 290:927–931, 1974)
TL;DR: Linkage analysis demonstrated that bacteriophage SPP1 transduced segments of the genome equal in size to that transferred by SP10, which should be useful in analyzing the regions of the genomes where PBS1 appears to give anomalous results.
Abstract: Lysates of the virulent bacteriophage SPP1 were shown to be capable of mediating generalized transduction. Suppressible mutants of this bacteriophage (sus) were capable of transduction at a lower multiplicity of infection than virulent SPP1. Linkage analysis demonstrated that bacteriophage SPP1 transduced segments of the genome equal in size to that transferred by SP10. This bacteriophage should be useful in analyzing the regions of the genome where PBS1 appears to give anomalous results.
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TL;DR: In a short-term memory experiment, signs of American Sign Language in list lengths of three to seven items were presented to deaf college students whose native language is American sign language as mentioned in this paper.
TL;DR: Assays of "total serum PTH" using the COOH-terminal antiserum correlated much better with the presence of suspected or proved hyperparathyroidism as well as with osteoclast counts in bone biopsy specimens from patients with primary hyperparathiroidism.
TL;DR: There is no data on whether spines are replaced when sprouting afferents invade deafferented dendritic zones, which is a critical question if the nature of the morphological reorganisation which follows lesions in the brain is to be understood.
Abstract: SEVERAL studies have reported that there is a loss of dendritic spines after partial deafferentation. It is known that terminals lost to a structure after injury to one of its afferents are replaced in part or whole by sprouting of undamaged inputs1–3. This raises questions as to the nature of the accompanying post-synaptic changes but no attempts have been made to follow the loss of spines over time4–6. Specifically, there are no data on whether spines are replaced when sprouting afferents invade deafferented dendritic zones. This is a critical question if the nature of the morphological reorganisation which follows lesions in the brain is to be understood.
TL;DR: Findings place severe constraint on possible models concerning the structure of the Tetrahymena macronucleus, and are very different from the situation observed in Stylonychia where it has been suggested that only a small percentage of the sequences in micronuclei are present in significant amounts in macron nuclei.
Abstract: Macro- and micronuclei were isolated from Tetrahymena pyriformis (Syngen 1, strain WH-6) and their DNAs compared by isopycnic centrifugation in neutral and alkaline CsCl, by analysis of thermal denaturation properties and by molecular hybridization. Unlike the situation observed in Stylonychia the buoyant densities and thermal denaturation patterns of Tetrahymena macro- and micronuclear DNAs were virtually identical—the only observable differences bordering on the limits of resolution of these techniques. DNA was isolated from the two nuclei which had been labelled with different radioactive isotopes (i.e.
14C-thymidine and 3H-thymidine), and the renaturation kinetics of mixtures of macro- and micronuclear DNA were examined using a single-strand specific deoxyribonuclease (S1). Renaturation kinetics obtained using varying ratios of macro- and micronuclear DNA suggested that 80–90% of the sequences present in micronuclei were present in similar amounts in macronuclei. However, careful analyses of the renaturation kinetics indicate that approximately 10–20% of the sequences found in micronuclei are probably absent in macronuclei, and that most of these sequences are probably moderately repetitive (100 copies per genome or less). These findings place severe constraint on possible models concerning the structure of the Tetrahymena macronucleus, and are very different from the situation observed in Stylonychia where it has been suggested that only a small percentage of the sequences in micronuclei are present in significant amounts in macronuclei. Nonetheless, these results along with those in Stylonychia can be taken as an indication that the loss or under-replication of some DNA sequences accompanies macronuclear differentiation in ciliates.
TL;DR: In this paper, the relationship between the algebraic structure of the underlying reaction network and the extent to which open isothermal reactors might give rise to such "exotic" dynamics is discussed.