Showing papers by "United States Department of Energy published in 1981"
TL;DR: In this article, the results gathered here on simple Lie algebras have been selected with attention to the needs of unified model builders who study Yang-Mills theories based on simple, local symmetry groups that contain as a subgroup the SUw2 × Uw1 × SUc3 symmetry of the standard theory of electromagnetic, weak, and strong interactions.
1,251 citations
TL;DR: Cytogenetic studies were performed on 26 patients who developed acute nonlymphocytic leukemia (ANLL) or a dysmyelopoietic syndrome after treatment of a primary malignancy, finding changes are distinctly different from those noted in lymphomas but similar to those seen in 25% of aneuploid patients with ANLL de novo.
442 citations
TL;DR: The report reviews and evaluates the current literature on chemically induced specific locus mutations in the V79 Chinese hamster lung cell line, and discusses the protocols for quantitative mutation studies including measurements of cytotoxicity, mutant expression times, mutant selection agents, cell densities during selection, and the stability and verification of mutant phenotypes.
Abstract: The report reviews and evaluates the current literature (about 125 primary publications) on chemically induced specific locus mutations in the V79 Chinese hamster lung cell line. The V79 cell is convenient to use for mutagenesis studies since it has a rapid growth rate, high plating efficiency, and a stable karyotype. Mutation can be easily measured at either the hypoxanthine-guanine phosphoribosyl transferase or the Na+/K+ ATPase locus, both of which have been well characterized. Other less-studied markers are also described. We discuss the protocols for quantitative mutation studies including measurements of cytotoxicity, mutant expression times, mutant selection agents, cell densities during selection, and the stability and verification of mutant phenotypes. Mutations in the V79 cells by chemicals that require activation can be tested after their metabolism by cell homogenates or by intact cells, and the results with each type of activation are compared. For purposes of analysis, we classified a compound as mutagenic if it induced a mutation frequency that is at least 3 times higher than the spontaneous mutant frequency reported for that specific experiment. By this criterion two-thirds of the chemicals analyzed were mutagenic--; 11% with and 55% without metabolic activation. Of the 191 chemicals examined; 119 were polycyclic aromatic hydrocarbons; 25 were nitro or nitroso compounds, 9 were alkyl halides; 7 were purine or pyrimidine derivatives and the remaining 31 were from other chemical classes. We also defined mutagenic potency as the concentration of a compound that increases the mutant frequency by 10 times the spontaneous frequency. Mutagenic potencies of the compounds examined varied over a range of 5 X 10(6). We have also found large interlaboratory variations in the mutagenic potencies. Such variation in potency could be reduced by normalizing the results to a standard mutagen such as N-methyl-N'-nitro-N-nitrosoguanidine. The role of the V79 assay in mutagenicity and carcinogenicity testing is discussed and recommendations are suggested for future investigation.
293 citations
TL;DR: Sediment cores from Sagamore Lake and Woods Lake in New York State's Adirondack Park were analyzed for polynuclear aromatic hydrocarbons (PAH) by high resolution gas chromatography/mass spectrometry (GC/MS) as discussed by the authors.
149 citations
TL;DR: The mouse specific-locus test with visible markers (SLT) has been the only extensively used method for detecting and quantifying the induction of heritable point mutations (intragenic changes and small deficiencies) in mammals.
Abstract: The mouse specific-locus test with visible markers (SLT) has been the only extensively used method for detecting and quantifying the induction of heritable point mutations (intragenic changes and small deficiencies) in mammals. Mutations are detected in first-generation offspring; and scoring is simple, objective, and rapid. Different germ-cell stages can be sampled, including those of greatest pertinence for genetic risk assessment. The differential probability of involving the various loci of the marked set makes the method capable of detecting qualitative (as well as quantitative) differences between the actions of mutagens. Control SLT frequencies for males reported by 4 sets of investigators are in excellent agreement and were summed as a "historical control" (801406 observations) for use in our calculations. Experimental results were classified as positive, negative, or inconclusive based upon a multiple-decision procedure produced by the testing of the following 2 hypotheses: (1) the mutation frequency (induced + spontaneous) of treated mice is not higher than the spontaneous mutation frequency, and (2) the induced mutation frequency of treated mice is no less than 4 times the historical-control mutation frequency. Each hypothesis was tested at the 5% significance level. Because of the low mutation frequency in a very large control, the SLT is capable of yielding positive results in relatively small samples. We reviewed 58 publications, SLT results have been reported for 25 chemical agents, of which 17 (representing 21 chemical classes) gave results that were positive or negative by our criteria. The frequency of positive agents was 6 of 14, 5 of 5, and 0 of 1 conclusively tested, respectively, in spermatogonia, post-spermatogonial stages, and unspecified male germ cells. Depending on the chemical used, post-spermatogonial stages can be of greater, less, or equal sensitivity relative to spermatogonia. The SLT was strongly positive for some chemicals that are not mutagenic (or only weakly so) in lower systems, and there are several examples of the reverse situation. Factors which presumably operated to cause these differences (e.g., metabolism, transport, repair in germ cells) are likely also to operate for transmitted point mutations in man.
142 citations
TL;DR: In this article, the retention, release, and isotope exchange of ion implanted hydrogen and deuterium in oarbon and Tic have been investigated as a function of temperature.
140 citations
TL;DR: In this article, a simple semiclassical method for calculating the polarizability of a very small spherical particle by taking into account the nonlocal nature of the dielectric response was developed.
Abstract: We develop a simple semiclassical method for calculating the polarizability of a very small spherical particle by taking into account the nonlocal nature of the dielectric response. Our theory is very general in the sense that it can be applied to any material which can be characterized by a bulk dielectric function of the form ${\ensuremath{\epsilon}}_{B}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}},\ensuremath{\omega})$: We introduce a new additional boundary condition (ABC) which is similar but not exactly equivalent to the Fuchs-Kliewer ABC. The theory is applied to calculate the polarizabilities of dielectric and metallic spheres.
136 citations
TL;DR: The GENE-TOX Group on Specific Gene Mutations in Chinese Hamster Ovary (CHO) Cells has evaluated the use of mutational systems in these cells for identification of mutagenic chemicals, finding the CHO/HGPRT assay has a sound genetic and biochemical basis for quantifying specific locus mutation reproducibly.
Abstract: The GENE-TOX Group on Specific Gene Mutations in Chinese Hamster Ovary (CHO) Cells has evaluated the use of mutational systems in these cells for identification of mutagenic chemicals from 261 references in the file of the Environmental Mutagen Information Center, Oak Ridge National Laboratory by February, 1979; 68 references were found to be relevant to the stated task. After establishing that the end-point of mutational measurement occurs at a specific locus and the determinations are quantifiable and reproducible, data from 21 references were found to fulfill such requirements. Among them, 14 were concerned with chemically-induced mutations to resistance to a purine analogue, 6-thioguanine, which selects for variants deficient in the enzyme hypoxanthine—guanine phosphoribosyl transferase (HGPRT). This mutational system is referred to as the CHO/HGPRT assay. Studies with other genetic markers offer promise for the development of quantitative specific genemutational assays, but these studies have not advanced thoroughly enough to assess their value. Several lines of genetic, physiological and biochemical evidence support the premise that the CHO/HGPRT system fulfills the criteria for measurement of specific gene mutations using CHO-K1-BH4 subclone and other appropriate CHO subclones. Based largely on published information, this Work Group has suggested a protocol for testing of chemical agents with consideration of the following: cells, media, culture conditions and their quality control, treatment with test compounds with and without an exogenous metabolic activation system, estimation of cytoxicity (cloning efficiency), optimum expression and selection of the mutant phenotype, calculation of mutation frequency, positive and negative controls, vehicles or solvents, spontaneous mutation frequency, dosage selection and number of doses, and collection of raw data. For interpretation of the mutagenesis data, this Work Group recommends various ways of presenting data, numerous criteria for acceptability of data, the need to use appropriate statistical procedures for data evaluation, and a potential applicability of results to hazard evaluation. Evaluation of test performances with 18 chemicals revealed that the correlation between mutagenicity in CHO/HGPRT assay and animal mutagenicity and carcinogenicity is high. Since the number of chemicals tested was small and 17 of the 18 compounds were direct-acting agents, the utility of the system for identification of various classes of potential mutagens and carcinogens cannot be adequately assessed until more chemical classes, especially promutagens, are tested. However, the assay has a sound genetic and biochemical basis for quantifying specific locus mutation reproducibly. The fact that CHO cells are also useful for determination of chemically-induced chromosome aberration and sister-chromatid exchange adds an additional strength to the assay. Future research should address the possible improvement of procedures for phenotypic expression and application for testing gaseous and volatile liquids, as well as such problems as appropriate metabolic activation system(s) and effective statistical procedures common to perhaps all short-term cellular assays. Recent rapid development of mutagen test systems like the CHO/HGPRT assay calls for a need to update and evaluate the data base generated.
135 citations
TL;DR: A review of ion implantation studies of the trapping of hydrogen and helium by simple defects in metals can be found in this article, where the increasingly strong evidence for the role of vacancies as trap centers is examined.
133 citations
TL;DR: In this article, a simple electron band theory model of the heat of formation ΔH, of transition metal alloys is used to predict Δ for 276 transition metal alloy at equiatomic composition.
Abstract: A simple electron band theory model of the heat of formation ΔH, of transition metal alloys is used to predict Δ for 276 transition metal alloys at equiatomic composition. The model employs a rectangular d-band electron density of states. Some of the input parameters, namely bandwidth, Fermi level position, and number of electrons in the band, are allowed to vary within certain constraints, to closely approximate any known value of ΔH. The resulting predictions are considered to have errors of the same order as the experiments.
117 citations
TL;DR: In this paper, a cross-polarization, magic-angle spinning 13C nuclear magnetic resonance spectra have been obtained on a series of coals that span the ASTM rank classification.
TL;DR: Sediment cores were taken from the remote Sagamore and Woods Lakes in New York State's Adirondack acid lake region and analyzed for 3 to 7 ring polycyclic aromatic hydrocarbons (PAHs) and Ag, Al, As, Be, Cd, Cr, Cu, Hg, Ni, Ph, Se, Sn, TI, V, and Zn.
Abstract: Sediment cores were taken from the remote Sagamore and Woods Lakes in New York State's Adirondack acid lake region and analyzed for 3 to 7 ring polycyclic aromatic hydrocarbons (PAHs) and Ag, Al, As, Be, Cd, Cr, Cu, Hg, Ni, Ph, Se, Sn, TI, V, and Zn. With the exception of perylene, all of the parental PAHs, e.g. those without sidechains, and several of the metals, Pb, As, and Cd, were found to be significantly increased in the sediments of both lakes compared to their natural integrated deposits (ng cm−2) and their background concentrations (μg g−1 or ng g−1 dry wt). Although the concentrations were generally much higher in Woods Lake, the total anthropogenic integrated depositions were about the same in both lakes for most of the metals and the 3 to 4 ring PAHs. The prime source of most of the 3 to 7 ring PAHs and trace elements measured is ascribed to anthropogenic combustion. Anthropogenically derived materials decreased in concentration with depth to baseline levels in sediment layers estimated by137Cs analyses to be ∼30 yr old, while biogenic or crustal derived species remained constant or fluctuated with core depth.
TL;DR: In this article, a reliability index for a model is defined, which is a number k ⩾ 1 which is determined from a set x 1, x 2, x n of model predictions and a corresponding set y 1, y 2,…, y n of observations.
TL;DR: A review of the present status of electric giant multipole resonances is provided in this paper, where the authors describe magnetic giant resonances, giant resonance decay modes, and theoretical implications of the new giant resonance.
TL;DR: In this article, the authors measured depth profiles for deuterium implanted in carbon at 530, 1500, and 3000 eV and calculated the retention with a Maxwellian velocity distribution to provide a new calibration for the determination of the energy and flux of deutium incident on carbon probes exposed to the edge of magnetically confined plasmas.
TL;DR: In this article, the powers of several nonparametric tests for the two-sample problem with censored data are compared by simulation and the test that performed the best overall was the Peto-Prentice generalized Wilcoxon statistic with an asymptotic variance estimate.
Abstract: The powers of several nonparametric tests for the two-sample problem with censored data are compared by simulation. The tests studied include Gehan's, Efron's, and Peto's, and Prentice's generalized Wilcoxon tests, along with the logrank test. The test with the greatest power changes with the sample sizes, censoring mechanism, and distribution of the random variables. The test that performed the best overall was the Peto-Prentice generalized Wilcoxon statistic with an asymptotic variance estimate.
TL;DR: In this article, the authors studied the electrokinetic behavior of oxidized coal and of hydrocarbon emulsion droplets of flotation reagents to indicate the feasibility of separating the oxidized coals from ash materials and pyrite by an oil flotation process.
Abstract: The objective of this investigation was to study the electrokinetic behavior of oxidized coals and of hydrocarbon emulsion droplets of flotation reagents to indicate the feasibility of separating the oxidized coals from ash materials and pyrite by an oil flotation process. The effects of surfactants and hydrolyzed metal ions were also included. The electrokinetic behavior of the oxidized coals and the hydrocarbon emulsion droplets were studied by an electrophoresis technique. Generally the isoelectric point (IEP) of the coals decreased with increasing degree of oxidation. A model of selective flotation of oxidized coal is postulated on the basis of the electrokinetic results. This model simply states that in the presence of a suitable amount of collector and frother, the optimal selective flotation of oxidized coal will occur at the IEP of the oxidized coal. To achieve this condition at the coal surface, it is necessary to adsorb heavy metal hydroxide ions prior to flotation and to absorb hydroca...
TL;DR: Since the spot test appears well suited to the identification of potent mutagens, its main value should be in screening large numbers of substances and singling out the potentially worst offenders to be further studied in germ-line mutagenesis tests.
Abstract: The mouse spot test, developed 23 years ago, is an in vivo assay capable of detecting genetic effects of several kinds, including intragenic mutations, minute deficiencies, deletions (through breakage or nondisjunction) of various amounts of chromosomal material, and somatic crossing-over. The method involves exposing embryos that are heterozygous for a number of coat-color markers to the test agent, and, 3 weeks later, looking for clones of mutant cells, i.e., spots of color expressing the recessive marker in an otherwise black fur. Spots having other causes may also be induced, specifically white midventral spots due to cytotoxic effects, and certain spots resulting from misdifferentiation. Spot-test results have, to date, been reported from 7 laboratories. Because the control results for any one cross and solvent were found to be reasonably consistent between the laboratories, we pooled these to develop a "historical" control with which experimental results for the same cross and solvent were compared. Experimental results were classified as positive, negative, or inconclusive on the basis of a multiple-decision procedure produced by the testing of the following 2 hypotheses: (1) the mutation frequency (induced + spontaneous) in treated mice is not higher than the mutation frequency in the appropriate pooled control, and (2) the induced mutation frequency of the treated mice is no less than 4 times as high as the observed mutation frequency in the appropriate pooled control. Each hypothesis was tested at the 5% significance level. To date, 30 substances have been employed in the spot test, including 3 that are solvents for some of the others. Of the remaining 27 (26 compounds and 1 mixture), 16 were positive, 6 negative, and 5 inconclusive. The 26 compounds fell into 27 chemical classifications (using a system provided for use by the GENE-TOX program). The inadequacies in the design and reporting of some past experiments indicate a need for a carefully specified protocol. When properly done, the spot test will fulfill a useful role in mutagenicity testing programs because (1) it is an in vivo mammalian assay, (2) it detects genetic effects of many kinds, and (3) it is relatively rapid. Since the test appears well suited to the identification of potent mutagens, its main value should be in screening large numbers of substances and singling out the potentially worst offenders to be further studied in germ-line mutagenesis tests.
TL;DR: The Aharonov-Bohm effect as discussed by the authors is a necessary and easily understood feature of conventional quantum mechanics and removing it from the theory must involve a drastic change in our understanding of the quantization and conservation of angular momentum, or of the classical equations of motion in quantum mechanics.
TL;DR: In this paper, the electronic structures of bulk refractory metal disilicides have been examined using photoelectron spectroscopy with synchrotron radiation, and the energy distribution curves measured for $9.
Abstract: The electronic structures of bulk refractory metal disilicides V${\mathrm{Si}}_{2}$, Ta${\mathrm{Si}}_{2}$, and Mo${\mathrm{Si}}_{2}$ have been examined using photoelectron spectroscopy with synchrotron radiation. Photoelectron energy distribution curves measured for $9\ensuremath{\le}\mathrm{hv}\ensuremath{\le}140$ eV show occupied bands (full width $\ensuremath{\simeq}12$ eV) dominated by metal $d$-derived states within 3-4 eV of ${E}_{F}$ and by $\mathrm{Si}3s$- and $3p$-derived features at higher binding energies. The $\mathrm{V}3p$, $\mathrm{Mo}4p$, $\mathrm{Ta}5p$, $\mathrm{Ta}4f$, and $\mathrm{Si}2p$ coreemission features are also shown. Self-consistent band calculations for a series of cubic silicides $M{\mathrm{Si}}_{3}$, $M\mathrm{Si}$, and ${M}_{3}\mathrm{Si}$ ($M$ denotes V or Mo) predict dominant metal $d$ character within 5 eV of ${E}_{F}$, $\mathrm{Si}s$ states centered at about - 10 eV, $\mathrm{Si}p$ states centered near - 5 eV, and substantial $M\ensuremath{-}\mathrm{S}\mathrm{i}$ hybridization, in agreement with experiment.
TL;DR: The isotope-type curves for these oils, the variations in isotopic composition as a function of compound group-type, were not found to be as simple as commonly believed as mentioned in this paper.
TL;DR: It is concluded that some of these test systems are effective tools for the detection of DNA-damaging and potentially carcinogenic compounds, especially if the assay is done in liquid suspension and if more than 1 pair of tester strains is used.
Abstract: The detection of DNA-damaging agents by repair-deficient bacterial assays is based on the differential inhibition of growth of repair-proficient and repair-deficient bacterial pairs. The various methodologies used are described and recommendations are made for their improved use. In a survey of the literature through April 1979, 91 of 276 papers evaluated contained usable data, resulting in an analysis of 611 compounds that had been assayed in 1 or more of 55 pairs of repair-proficient and repair-deficient strains. The results indicate that (1) a liquid suspension assay is more sensitive than a spot (diffusion) test. In a review of the Escherichia coli polA assay, 45 compounds that gave "No Test" in the spot test were clearly positive or negative in the liquid suspension assay. (2) Of the 21 compounds analyzed by the E. coli polA assay and by other E. coli repair-deficient strains (e.g., rec, uvr, hcr, and exr derivatives of WP2 and AB1157), 10 were in complete agreement in all strains except uvrA strains. This indicates that strains other than polA+/polA- are useful for detecting DNA-damaging agents. However, in selecting strains for use in these assays, care should be taken to consider repair pathway specificity for particular compounds. (3) There was a 78% correspondence between results obtained with E. coli polA and Bacillus subtilis (H17/M45, 17A/45T) rec assay and between E. coli polA and Proteus mirabilis. (4) In a comparison of test results with carcinogenicity data, 44 of 71 (62%) carcinogenic compounds assayed by the polA system were positive, 10 (14%) were negative, and 17 (24%) gave No Test or doubtful results. 7 carcinogens were assayed by other E. coli strains and all were positive. 56 carcinogens were assayed in B. subtilis: 24 (43%) were positive, 9 (16%) were negative, and 23 (41%) gave No Test or doubtful results. Of the 7 carcinogens assayed in P. mirabilis, 6 (86%) were positive and 1 (14%) was negative. (5) The results were analyzed with respect to chemical classes. E. coli polA detected the highest percentage of hydroxylamines and alkyl epoxides. The B. subtilis rec assay detected the highest percentage of nitrosamines and sulfur and nitrogen oxides. It is concluded that some of these test systems are effective tools for the detection of DNA-damaging and potentially carcinogenic compounds, especially if the assay is done in liquid suspension and if more than 1 pair of tester strains is used. Advantages and disadvantages of the assay are discussed and suggestions are made for improvements in the system.
TL;DR: Consideration of the epidemiological evidence on radiogenic lung cancer in uranium miners and of the incidence of the disease generally leads to an upper estimate for the lifetime risk of 10−4 cases per working level month for the general population.
Abstract: Consideration of the epidemiological evidence on radiogenic lung cancer in uranium miners and of the incidence of the disease generally leads to an upper estimate for the lifetime risk of 10−4 cases per working level month for members of the general population.
TL;DR: In this article, mass spectral data were obtained for the saturated hydrocarbons of the naphtha and light distillate fractions of the Green River formation in Southwestern Wyoming.
TL;DR: In this paper, the development of magnetic order in the region of the reentrant superconducting transition in Ho${\mathrm{Mo}}_{6}$${S}}_{8} was investigated.
Abstract: Neutron scattering has been used to investigate the development of magnetic order in the region of the reentrant superconducting transition in Ho${\mathrm{Mo}}_{6}$${\mathrm{S}}_{8}$. On cooling, an ordered oscillatory magnetic state develops in the superconducting phase, with a wavelength which increases with the application of a magnetic field. On further cooling the sample reverts to the normal conducting state as ferromagnetism sets in. No oscillatory magnetic phase is observed, however, when the superconducting phase is approached from low temperatures.
TL;DR: In this paper, a cylindrical cavity expansion approximation is employed which idealizes the target as thin independent layers normal to the penetration direction and permits one-dimensional wave propagation calculations in the radial coordinate.
TL;DR: In this paper, the authors considered the problem of a uniaxial type-II superconductor near the upper critical field in the framework of the Ginzburg-Landau equations with a phenomenological mass tensor.
Abstract: The problem of a uniaxial type-II superconductor near the upper critical field is considered in the framework of the Ginzburg-Landau equations with a phenomenological mass tensor. The currents are shown to flow in planes which are in general no longer orthogonal to the direction of the vortex axes as in the isotropic case; the inclination angle is obtained in terms of anisotropic masses. The magnetic field has a component normal to the vortex axes; equations are derived which relate the transverse and axial fields. The average value of the transverse field (the transverse induction) vanishes. The constitutive relation between the induction and the magnetization is obtained. The components of the magnetization normal and parallel to the vortex direction are simply related in terms of the effective masses.
TL;DR: In this article, the effect of spin diffusion on nuclear magnetic resonance in disordered solids with a spatial distribution of resonance frequency was investigated in the limits of (a) rapid diffusion, and (b) slow diffusion:
Abstract: The spin-flip diffusion equation for the local magnetization in solids is derived using Mori's equation of motion with the emphasis on the types of approximations involved. The spin-flip diffusion coefficient is expressed in terms of the local dipolar field. Comparison with other theories is also given. The effect of spin diffusion on nuclear magnetic resonance in disordered solids with a spatial distribution of resonance frequency $\ensuremath{\omega}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$ and longitudinal spin-relaxation time ${T}_{1}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$ has been investigated in the limits of (a) rapid diffusion: $D{l}^{\ensuremath{-}2}\ensuremath{\gg}|\ensuremath{\Delta}A|$, and (b) slow diffusion: $D{l}^{\ensuremath{-}2}\ensuremath{\ll}|A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})|$ and $|\ensuremath{\Delta}A|$. $D$ is the spin diffusion coefficient, $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})=\ensuremath{-}i\ensuremath{\omega}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$ or ${T}_{1}{(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}^{\ensuremath{-}1}$, $|\ensuremath{\Delta}A|$ is the maximal variation in $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$, and $l$ is the average distance between extrema in $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$. In the rapid diffusion limit, the case of $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})={T}_{1}{(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}^{\ensuremath{-}1}$ and $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})=\ensuremath{-}i\ensuremath{\omega}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$ can be studied under the same treatment based on cumulant expansion method or second-order perturbation theory. Both yield the same results. The line shape is found to be a motionally narrowed Lorentzian whose width is determined by the spatial correlation of $\ensuremath{\omega}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$; in comparison with the result in the limit of $D\ensuremath{\rightarrow}\ensuremath{\infty}$, the longitudinal relaxation time of the sample as a whole is lengthened. The difference is determined by the spatial correlation of $\frac{1}{{T}_{1}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}$. On the other hand in the slow diffusion limit, the case of $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})={T}_{1}{(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}^{\ensuremath{-}1}$ and $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})=\ensuremath{-}i\ensuremath{\omega}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$ have to be studied separately. Hee selective summation of a perturbation expansion to an infinite order is involved. The procedure by which such expansion is summed depends on whether $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$ is real [$A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})={T}_{1}{(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}^{\ensuremath{-}1}$] or imaginary [$A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})=\ensuremath{-}i\ensuremath{\omega}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$]. The individual absorption line is now broadened by spin diffisuion. In both limits, analytic expressions of the line broadening and the lengthening of the relaxation time are given. The differences between these results and those of $D=0 \mathrm{and} \ensuremath{\infty}$ yield information about the spatial distribution of $A(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$.
Patent•
29 May 1981TL;DR: An apparatus and method for injecting a substance, such as a radiopharmaceutical, into the bloodstream of a subject is described in this paper, where an error signal proportional to the difference between the concentration of the substance in the subject's bloodstream and a predetermined function of time is calculated.
Abstract: An apparatus and method for injecting a substance, such as a radiopharmaceutical, into the bloodstream of a subject. The apparatus comprises an injection means, such as a servo controlled syringe, a means for measuring the concentration of that substance in the subject's bloodstream, and means for controlling the injection in response to the measurement so that the concentration of the substance follows a predetermined function of time. The apparatus of the subject invention functions to inject a substance into a subject's bloodstream at a rate controlled by an error signal proportional to the difference between the concentration of the substance in the subject's bloodstream and the predetermined function.
TL;DR: In this paper, a numerical solution of the Fokker-Planck equation is used to verify the theory of Fisch and Boozer and to extend their results into the non-linear regime.
Abstract: Certain aspects of the generation of steady-state currents by electron cyclotron waves are explored. A numerical solution of the Fokker-Planck equation is used to verify the theory of Fisch and Boozer and to extend their results into the non-linear regime. Relativistic effects on the current generated are discussed. Applications to steady-state tokamak reactors are considered.