Showing papers by "State University of New York System published in 1975"

Transition temperature of strong-coupled superconductors reanalyzed

Abstract: A through analysis is made of the dependence of the superconducting transition temperature ${T}_{c}$ on material properties ($\ensuremath{\lambda}$, ${\ensuremath{\mu}}^{*}$, phonon spectrum) as contained in Eliashberg theory. The most striking new feature of the analysis is in the asymptotic regime of very large $\ensuremath{\lambda}$ where ${T}_{c}$ is found to equal $0.15 {(\ensuremath{\lambda}〈{\ensuremath{\omega}}^{2}〉)}^{\frac{1}{2}}$ (assuming ${\ensuremath{\mu}}^{*}=0.1$). This result implies the surprising conclusion that within Eliashberg theory ${T}_{c}$ is not limited by the phonon frequencies, and also shows that McMillan's "$\ensuremath{\lambda}=2$ limit" is spurious. The McMillan equation (with a prefactor altered from $\frac{{\ensuremath{\Theta}}_{D}}{1.45}$ to $\frac{{\ensuremath{\omega}}_{log}}{1.2}$) is found to be highly accurate for all known materials with $\ensuremath{\lambda}l1.5$ but in error for large values of $\ensuremath{\lambda}$. Correction factors to McMillan's equation are found in terms of $\ensuremath{\lambda}$, ${\ensuremath{\mu}}^{*}$, and one additional parameter, $\frac{{(〈{\ensuremath{\omega}}^{2}〉)}^{\frac{1}{2}}}{{\ensuremath{\omega}}_{log}}$. The frequency ${\ensuremath{\omega}}_{log}$ is defined as $\mathrm{exp} 〈\mathrm{ln}\ensuremath{\omega}〉$ where the averages $〈\mathrm{ln}\ensuremath{\omega}〉$ and $〈{\ensuremath{\omega}}^{2}〉$ are defined using $(\frac{2}{\ensuremath{\lambda}\ensuremath{\omega}}){\ensuremath{\alpha}}^{2}F(\ensuremath{\omega})$ as a weight factor. These conclusions are based on a combination of analytic and numerical solutions of the Eliashberg equations, and are supported by a comparison with tunneling data. Especially strong support comes from a new experimental result for amorphous ${\mathrm{Pb}}_{0.45}$${\mathrm{Bi}}_{0.55}$ reported herein. This material has parameters $\ensuremath{\lambda}=2.59$ and $\frac{{T}_{c}}{{\ensuremath{\omega}}_{log}}=0.284$, in serious disagreement with McMillan's formula but in good agreement when the correction factors are included. The McMillan-Hopfield parameter $\ensuremath{\eta}$ [or $N(0) 〈{I}^{2}〉$] is extracted from tunneling measurements or from a combination of empirical values of $\ensuremath{\lambda}$ and neutron-scattering measurements of phonon dispersion. It is proposed that $\ensuremath{\eta}$ (which is now known not to be accurately constant) is the most significant single parameter in understanding the origin of high ${T}_{c}$ and the limitation of ${T}_{c}$ by colvalent instabilities.

Concept of Nonintegrable Phase Factors and Global Formulation of Gauge Fields

Abstract: Through an examination of the Bohm-Aharonov experiment an intrinsic and complete description of electromagnetism in a space-time region is formulated in terms of a nonintegrable phase factor. This concept, in its global ramifications, is studied through an examination of Dirac's magnetic monopole field. Generalizations to non-Abelian groups are carried out, and result in identification with the mathematical concept of connections on principal fiber bundles.

Model for a multicomponent quantum system

Abstract: In a recent paper, Lai introduced a lattice-gas model. In this paper we generalize Lai's model, making application to various systems such as dilute Heisenberg magnets, higher-spin systems, and a lattice of SU(3) triplets. By a careful consideration of general thermodynamic stability, and by variational arguments, we demonstrate Lai's solution to be incorrect, and in turn produce the correct solution in this case and in other cases including higher-dimensional models. The remaining cases we treat in one dimension by Bethe's ansatz, reducing the problem to coupled integral equations. We locate the singularities of the ground-state energy in the phase plane; and we explicitly calculate the absolute-ground-state energy, excitations above the absolute ground state, and the first correction to the absolute ground state for small concentrations of impurities.

A vaginal plethysmograph system.

Abstract: A vaginal plethysmograph system utilizing an indirectly (reflected) lighted photocell probe has been developed and used experimentally with excellent results. While the standard lamp and photocell plethysmograph using transmitted light is not unique, its application in measuring vaginal blood volume presented numerous instrumentation and mechanical problems not previously encountered. It is believed that this is the first system to reliably measure vaginal blood volume changes by indirect methods.

Use of an angiotensin II antagonist (saralasin) in the recognition of "angiotensinogenic" hypertension;.

Abstract: The possibility has been explored of using a specific angiotensin II antagonist, saralasin (P-113, 1-sar-8-ala-angiotensin II) to recognize patients whose hypertension depends upon excessive angiotensin II activity. Among 60 hypertensive patients, saralasin infusion reduced blood pressure in 16 "responders," but not in 44 "nonresponders." The "responders" had the following findings: elevated plasma renin activity in renal vein (or veins) or peripheral veins or both (16 of 16); reduced renal blood flow, shown by arteriography, isotopic studies or pyelography (15 of 16), or progressive azotemia (one of 16); and reduction in blood These findings indicated that angiotensin II probably caused hypertension in the "responders." One "nonresponder" had renal vein levels of plasma renin activity suggestive of angiotensinogenic hypertension. Since hypertension was invariably angiotensinogenic when it was reduced by saralasin and, with one possible exception, was never angiotensinogenic in "nonresponders," t...

The two-stream approximation in radiative transfer Including the angle of the incident radiation

Abstract: The two-stream approximation has been applied to the equation of radiative transfer to obtain two–stream models for the transfer of radiation through an optically thin plane-parallel atmosphere. The models include the dependence of the reflection and the transmission of the atmosphere on the angle of the incident radiation and on the angular dependence of the scattering phase function of the medium. The two models arise from different methods for treating the incident radiation. It is shown that the models reduce to the thin-atmosphere approximation in the limit that the optical depth of the atmosphere approaches zero. In this limit the sign of the heating caused by the presence of a scattering and absorbing layer over a reflecting surface is derived. This reveals the importance of both the zenith angle and the angular dependence of the scattering phase function. The results obtained from the two-stream models are compared with those of numerical solutions to the equation of radiative transfer. I...

Tissue ingrowth of Replamineform implants.

Abstract: The Replamineform process, a new technique for the fabrication of porous hard tissue implant materials which replicates the skeletal configuration of certain marine invertebrates, was used to manufacture 1 cm long by 0.5 cm diam cylinders. The inherent advantages of porous configurations obtained through this process are controlled, uniform pore size, controlled pore-microstructure ratio, and complete interconnection of pores. The specific materials studied were chrome-cobalt-molybdenum alloy, alphaA103, hydroxyapatite prepared by hydrothermal conversion, and the basic (aragonite) CaCO3 skeleton of the coral genus Porities. The implants were placed in the canellous bone of the distal femora and proximal tibiae of adult, mongrel dogs and analyzed at 8 weeks for tissue response and ingrowth. Uniformly, new bone was found to grow into the pores of these materials and become normally mineralized. These findings were determined by microradiography, scanning electron microscopy, electron microprobe analysis, and histology. No evidences of infection, rejection, or encapsulation were seen. In the case of those CaCO3 implants left in place for 1 year, there was almost complete resorption of the cylinders, with both bony trabeculae and unmineralized collagen (presumably osteoid) found at the sites of insertion.

Image approximation to the reaction field

Abstract: The reaction field for a charge at an arbitrary position in a spherical cavity in a medium of dielectric constant e may be expressed in terms of the electrical potential of a certain image charge. For e τ 1 the potential of the reaction field in the cavity is quite accurately the same as the electrical potential of the image charge. These observations form the basis of a rather economical and accurate way to calculate the reaction field's contribution to the interaction potential of particles with electric moments within a cavity within a dielectric. The results promise to be useful in the study of models for polar fluids and solutions by the Monte Carlo and Molecular Dynamics methods.

Cross-wire anemometry in high intensity turbulence

Abstract: An analysis of the response of an X-probe which takes into account the axial sensitivity k, the effect of the w component of velocity and the effective rectification by the hot wire is presented. Owing to rectification points in the measured u, v ‘phase plane’ are confined within a certain sector, thus leading to distortions in the measured joint probability density functions. Numerical computations show that high turbulence intensities lead to large errors in second-order moments measured by cross-wire probes; for instance, the error in the measured correlation (over and above that due to k) can be as high as 28% when the turbulence intensity is 35%.

Growth and form in the reef-building coral Montastrea annularis

Abstract: The in-situ growth rate of the reef coral Montastrea annularis on a reef at Jamaica, W. Indies was determined for a 1-year period using Alizarin Red-S staining techniques. Growth rate is correlated with water depth and growth form. The flattened growth form of M. annularis allows for continued rapid increase in colony surface area at low light intensities. The geomorphology of Jamaican reefs may in part be controlled by the population ecology of M. annularis.

Genetic organization and adaptive response of allozymes to ecological variables in Fundulus heteroclitus.

Abstract: Populations of Fundulus heteroclitus, (Cyprinodontidae) a widespread coastal marine fish, were studied in control and artificially heated environments on the North Shore of Long Island, New York to determine (1) patterns of variation in biochemical phenotypes and (2) the extent to which this variation reflected adaptation to environmental characteristics. Variation at three of twelve polymorphic isoenzyme loci from the warm water population was beyond the range of variation among control populations, and resembled those determined for populations living at more southern latitudes. Hence, these differences were interpreted as adaptations to warm environments. Significant differences in allele frequencies and zygotic proportions at ten of twelve isoenzyme loci were found associated with differences in environments, sexes, and/or age classes. These data strongly support the view that protein polymorphisms are adaptive. Several observations suggested that selection acts upon multilocus phenotypes rather than upon those of single loci. Several di-locus phenotypic distributions were demonstrated to be nonrandom, and those that exhibited similar patterns of dependence over years were postulated to be maintained by selection. Highly heterozygous fish exhibited superior viability when cohorts were compared over successive years. The consequences of the polygynous mating system in this species for maintaining genetic variation and for allowing rapid evolutionary response to a variable environment are discussed.

Pharmacokinetics of acetaminophen in the human neonate: formation of acetaminophen glucuronide and sulfate in relation to plasma bilirubin concentration and D-glucaric acid excretion.

Abstract: The purpose of this study was to determine if certain physiologic parameters (plasma bilirubin concentration and urinary excretion rate of D-glucaric acid) can be used to predict a newborn infant's ability to eliminate a phenolic drug, and particularly to predict the ability to conjugate that drug with glucuronic acid. Tweleve healthy 2- to 3-day-old full-term infants with plasma bilirubin concentrations of 1.0 to 11.6 mg/100 ml and D-glucaric acid excretion rates of 0.131 to 0.345 mg/kg/day received a single oral dose of acetaminophen, 12 mg/kg. Urine was collected serially for 48 hours and analyzed for acetaminophen, acetaminophen glucuronide, acetaminophen sulfate, and D-glucaric acid. The biologic half-life of acetaminophen was 3.5 plus or minus 0.85 hours (average plus or minus SD) as compared to average values of 1.9 to 2.2 hours observed in five reported studies on a total of 39 adults. The rate constant for acetaminophen glucuronide formation in neonates was considerably smaller, on the average, than in adults but the average rate constant for acetaminophen sulfate formation was somewhat larger than in adults. There is not statistically significant colucaric acid excretion. The results of this study suggest that the limited ability of neonates to conjugate phenolic drugs with glucuronic acid is compensated to a degree by a well-developed capability for sulfate conjugation.

Chemical attractants for the smaller european elm bark beetle Scolytus multistriatus (Coleoptera: Scolytidae)

Abstract: The secondary attractant for the smaller European elm bark beetleScolytus multistriatus is a mixture of three compounds: (-)4-methyl-3-heptanol(I); 2,4-dimethyl-5-ethyl-6,8-dioxabicyclo(3.2.1) octane (II); and (−)α-cubebene (III). The novel structure assigned to compound II was confirmed by synthesis. All three compounds were isolated from the volatile compounds collected on Porapak Q by aerating elm bolts infested with virgin female beetles. The GLC fractionations were monitored by two laboratory bioassays. Individually, each compound was inactive in the laboratory bioassays, but a mixture of all three showed activity nearly equivalent to that of the of the original Porapak extract. A mixture of synthetic I and II plus natural III (from cubeb oil) was highly attractive to beetles in preliminary field tests.

Some remarks about unquantized non-Abelian gauge fields

Abstract: For unquantized non-Abelian gauge fields, remarks are made on the question of whether the field strengths determine the gauge field, on the dual transformations, and on complex gauge fields.

Porapak-Q collection of airborne organic compounds serving as models for insect pheromones

Abstract: Organic compounds with properties resembling those of insect pheromones can be removed from an airstream by absorption on Porapak Q and recovered from the absorbent by extraction. When this procedure is applied to aeration of live insects, the Porapak extract represents a concentration of the chemical message.

Plant mycoplasmas: a cultivable spiroplasma causes corn stunt disease.

Abstract: A spiroplasma can be isolated and grown continuously in cell-free medium from stunted corn or from Drosophila injected with sap expressed from diseased corn. The organism is serologically related to, but not identical with, Spiroplasma citri, the causative agent of citrus stubborn disease. Leafhopers injected with cultured organisms induced typical symptoms of the corn stunt disease when placed on previously healthy corn plants.

Cosmic-ray streaming and anisotropies

Abstract: The paper is concerned with the differential current densities and anisotropies that exist in the interplanetary cosmic-ray gas, and in particular with a correct formulation and simple interpretation of the momentum equation that describes these on a local basis. Two examples of the use of this equation in the interpretation of previous data are given. It is demonstrated that in interplanetary space, the electric-field drifts and convective flow parallel to the magnetic field of cosmic-ray particles combine as a simple convective flow with the solar wind, and that there exist diffusive currents and transverse gradient drift currents. Thus direct reference to the interplanetary electric-field drifts is eliminated, and the study of steady-state and transient cosmic-ray anisotropies is both more systematic and simpler.

Pharmacokinetics of Digoxin in Normal Subjects After Intravenous Bolus and Infusion Doses

Abstract: Normal subjects were given 0.75 mg of intravenous digoxin as a bolus and a 1-hr infusion, Radio-immunoassayed serum concentrations obtained over 48 hr and urinary excretion rates over 6 days were simultaneously fitted to a two- compartment open model by computer nonlinear least-squares regression. Serum concentration data alone were also fitted by this program. There was good agreement in calculated parameters between the two routes of administration in five of eight subjects, but the infusion mode of administration produced less variability in the apparent pharmacokinetic constants. The β half-life values obtained from serum concentration data alone (24.2 hr) underestimated the half-lives obtained by the simultaneous fit (44.1 hr). The steady-state volume of distribution of digoxin averaged 590±164 liters (±1sd).The renal clearance of digoxin (140±41 ml/min/1.73 m 2 )was significantly higher than creatinine clearance (101±13 ml/min/ 1.73 m 2 ),indicating tubular secretion of the drug. Digoxin body clearances were 188±44 ml/min/ 1.73 m 2 ,indicating elimination of 25% of the dose by nonrenal mechanisms. Urinary excretion data are essential for proper pharmacokinetic analysis of digoxin disposition and reveal a slower rate of elimination than that suggested by earlier studies which determined only serum concentrations.

Replamineform porous biomaterials for hard tissue implant applications.

Abstract: By means of the newly developed Replamineform process, the unique pore microstructures found in the skeletal calcium carbonate of certain reef corals can be replicated or reproduced with high precision in a wide variety of materials suitable for hard tissue implant and prosthetic applications. The advantages of fabricating porous biomaterials with this method include closely controlled size of both the pore diameters and the diameters of the pore interconnections, and virtually complete interconnection of the uniformly spaced pores. These properties are of great importance in implant devices, because tissue ingrowth, the stimulation of new bone formation, the suppression of undesirable scar tissue, the inhibition of adverse body responses, and firm biological fixation of the implanted material all depend upon the nature of the pore-microstructure configuration. Replamineform preparation of Al2O3, TiO2, hydroxyapatite, silver, Co-Cr-Mo alloys, and polymers is described in detail, and the characterization procedures used to determine the physical and structural properties of their materials are discussed. A few of the routinely measured characteristics include (1) quantitative computerized SEM image analysis for determining the volume, size and shape distributions of the macro and microporosity and the grain size measurement of the solid; (2) nondestructive x-radiography of specimens to reveal any internal defects; (3) mechanical strength measurements of randomly selected specimens. Experimental results up to now clearly demonstrate the superiority of microstructures imparted to metals, ceramics, and polymers with the Replamineform process.