Showing papers by "University of Virginia published in 1968"
TL;DR: In this article, a lattice contraction of small (2 r = 35 A to 125 A) gold nuclei is observed as a function of their radii, interpreted in terms of surface stress, and a value of 1175 dyn/cm is obtained for the surface stress of gold, at a temperature of approximately 50°C.
356 citations
TL;DR: The physical significance of the difference between surface tension, σ, and surface stress, fij = σ + ∂σ∂eij, with δij the Kronecker delta, is investigated in this article, where it is concluded that the strain concerned is not the total strain, which may be composed of elastic and plastic contributions, but only the elastic component of the strain.
226 citations
TL;DR: In this article, a general dynamical scaling theory of phase transitions is established by exploiting the absence of a characteristic length in an extended system at its phase transition, which imposes strong constraints on the frequency and wave-number dependence of the fluctuation spectrum and leads to unambiguous predictions concerning the critical properties.
182 citations
TL;DR: A retrospective analysis of drugs as possible etiologic factors in 138 cases of Stevens-Johnson syndrome made at five university medical centers from 1952 through 1965 is presented, providing little basis for suspecting long-acting sulfonamides as an important Etiologic factor in the Stevens- Johnson syndrome.
123 citations
TL;DR: The synthesis of lens proteins during differentiation of the chicken lens was studied with antisera to adult lens and to fractions isolated by polyacrylamide gel electrophoresis as discussed by the authors.
122 citations
TL;DR: In this article, an experimental oligopoly market is presented, where price variations models of oligopoly are used. But the authors focus on price variation models and do not consider the effect of price variations on the overall market.
Abstract: I. Introduction, 240. — II. Price variations models of oligopoly, 241. — III. An experimental oligopoly market, 242. — IV. Hypotheses, 248. — V. Procedure, 249. — VI. Results, 251. — VII. Discussion, 257. — VIII. Summary and conclusions, 259.
121 citations
TL;DR: The primary products of the reaction of lithium atoms and carbon tetrachloride in solid argon at 15°K are lithium chloride and the trichloromethyl radical, which are identified by infrared spectral studies.
Abstract: The primary products of the reaction of lithium atoms and carbon tetrachloride in solid argon at 15°K are lithium chloride and the trichloromethyl radical, which are identified by infrared spectral studies. Natural chlorine isotopes, carbon 13 and bromine substitution, and loss of CCl3 absorptions with attendant growth of absorptions due to C2Cl6 on sample warming verify the molecular identity. Assignments to the carbon–chlorine stretching vibrations ν1 = 674 and ν3 = 898 cm−1 are supported by normal coordinate calculations, and the weak bending modes ν2 and ν4 were not detected. The stretching force constants Fτ = 3.83 mdyn / A and Fττ = 0.43 mdyn / A are compared with those of other chlorocarbons and BCl3 This comparison supports proposed resonance stabilization of the trichloromethyl radical.
121 citations
TL;DR: The concentrations of copper, zinc, iron, and magnesium have been determined by atomic absorption spectroscopy for various regions of the brain in cases restricted to non-neurologic disorders.
107 citations
TL;DR: Indomethacin may be useful in treating other nonrheumatoid rheumatic diseases, but as yet few comparisons with standard therapies have been made and the drug has severe side effects and should be used with caution.
Abstract: Clinical trials of indomethacin in rheumatic diseases are reviewed. In treating rheumatoid arthritis, the good results observed in uncontrolled subjective and objective evaluations have not been confirmed in recent controlled double‐blind trials. Failure to account for natural remission and cyclic variation in disease activity in uncontrolled trials probably explains these differences. There is no clear reason for preferring this drug over aspirin in treating rheumatoid arthritis. Indomethacin may be useful in treating other nonrheumatoid rheumatic diseases, but as yet few comparisons with standard therapies have been made. The drug has severe side effects and should be used with caution. Problems encountered in collecting information about this drug and its toxicity are discussed. The controlled double‐blind trial appears to be the only feasible method for assessing both the efficacy and the toxicity of drugs used in treating rheumatoid arthritis.
88 citations
87 citations
TL;DR: The isotopic chloride flux was examined in detail and shown to exhibit saturation kinetics, and the difference between this flux and the value calculated from the electrical parameters may be accounted for by assuming the existence of an auxiliary carrier-mediated diffusion mechanism for chloride permeation.
TL;DR: The histologic features required to make a diagnosis of primary melanoma of the lung or bronchus are demonstrated in this case and it is suggested that since melanoma may occur fairly commonly in juxtacutaneous mucous membranes, it is not unreasonable to see a few cases in an adjacent site such as the lung.
Abstract: This paper describes a case of primary melanoma of the lung. The histologic features required to make a diagnosis of primary melanoma of the lung or bronchus are demonstrated in this case. It is suggested that since melanoma may occur fairly commonly in juxtacutaneous mucous membranes, it is not unreasonable to see a few cases in an adjacent site such as the bronchus of the lung.
TL;DR: It is proposed that the ATPase localized on the stacks of lateral plasma membrane may be involved with ion secretion into the intercellular spaces to create the osmotic gradient necessary to extract water from the lumen.
Abstract: Adenosine triphosphatase (ATPase) activity in the rectal papillae of Calliphora has been studied by biochemical and histochemical techniques The microsomal fraction contained a Mg 2+ -activated ATPase with a pH optimum of 80 The enzyme was not stimulated by the addition of Na + plus K + and was insensitive to ouabain Histochemical studies using modifications of the Wachstein-Meisel method showed that at pH 72 this Mg 2+ -activated ATPase was specifically localized on the intracellular surface of the lateral plasma membranes A similar though less intense reaction was obtained with adenosine diphosphate and inosine triphosphate, but not with guanosine triphosphate, uridine triphosphate or β-glycerophosphate as substrates At an acid pH (66-68), very little reaction occurred on the lateral plasma membrane but some reaction product was present in mitochondria and nuclei Very little enzyme activity was found in the flattened rectal epithelium These results are discussed in relation to the available data on transport ATPases and on the structural basis of fluid transport by rectal papillae It is proposed that the ATPase localized on the stacks of lateral plasma membrane may be involved with ion secretion into the intercellular spaces to create the osmotic gradient necessary to extract water from the lumen
TL;DR: The temperature dependence of the resistance of iron has been measured in the range 1 to 42 as discussed by the authors, with average coefficients of 82, 82, 84, and 84 degrees in the flux closed and -saturated states, respectively.
Abstract: The temperature dependence of the resistance of iron has been measured in the range 1 to 42\ifmmode^\circ\else\textdegree\fi{}K Single-crystal iron specimens 100 to 300 \ensuremath{\mu} in diameter with residual resistance ratios up to 2100 were used in the experiments The dominant temperature dependence in this range is linear with average coefficients of 82\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ and $214\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}{\ensuremath{\mu}}_{A}$ cm/\ifmmode^\circ\else\textdegree\fi{}K in the flux-closed and -saturated states, respectively These coefficients are an order of magnitude larger than those observed by previous experimenters Careful control of the magnetic state of the crystal seems to remove most of the ${T}^{2}$ dependence in this temperature range The results are discussed in terms of the general electron-magnon scattering theories developed by Turov Deviations from Ohm's law and large negative magnetoresistance effects are observed, and these are taken into account in making the measurements Preliminary measurements have also been made in the range 77 to 294\ifmmode^\circ\else\textdegree\fi{}K, and results are in general agreement with previous measurements by White and Woods
TL;DR: Findings are in disagreement with some of the current theories on the regulation of lens differentiation and suggest a differential production onset for the components of each single crystallin type.
Abstract: Polycrylamide gel electrophoresis of chicken lens proteins showed 17 crystallins, divided over three groups. Within each group physicochemical heterogeneity was combined with (partial) immunological homogeneity. It is assumed that more than one gene is involved in the synthesis of any crystallin species. During development of the chicken embryo, α-crystallin was first demonstrated by immunofluorescence in centrally located lens fibers at 3 days. At 8 days the epithelium became positive and the fibers lost some fluorescence. This continued until in 5-week-old chickens the lens core was negative. Lens placode cells showed immunofluorescence for δ-crystallin at 52 hours, mainly in their basal parts. The reaction gradually spread and at 3 days the entire lens was positive. From 8 days on the epithelium reacted progressively weaker, but the fibers remained positive. Five weeks after hatching, epithelium and cortex were negative, while the center still showed strong fluorescence. The behavior of β-crystallin was intermediate between that of the other two. Immunoelectrophoresis suggested a differential production onset for the components of each single crystallin type. Under normal conditions no crystallins were found outside the lens. Therefore, crystallin synthesis occurs after placode formation has taken place and must be restricted to the lens itself. Autoradiography after 3H-thymidine treatment indicated that all placode cells still replicate, though some already produce crystallins. A generation time of 8 to 10 hours was determined with an M phase of 30 minutes, an S phase of 6 hours, and a G2 of 2 ½ hours. During DNA synthesis the nuclei were located in the basal parts of the cells, and for mitosis they migrated to the lumen. Autoradiography after 3H-glucosamine application suggested that the placode cells take active part in the synthesis of the basement membrane interposed between lens rudiment and optic cup. This membrane later becomes the lens capsule, and in mice with the “shrivelled” gene, abnormal masses of anterior epithelial cells also clearly produce extra capsule material. This results in anterior polar cataracts. Several of the above findings are in disagreement with some of the current theories on the regulation of lens differentiation. No substitutes are presently offered, however.
TL;DR: Pituitary gland prolactin and growth hormone content are decreased in rats bearing certain hormone-secreting pituitary tumors, but the present study shows that this is the result of decreased hormone synthesis and not increased release of pituitsary gland hormones.
Abstract: Pituitary gland prolactin and growth hormone content are decreased in rats bearing certain hormone-secreting pituitary tumors. The present study shows that this is the result of decreased hormone synthesis and not increased release of pituitary gland hormones. Pituitary glands were incubated in vitro in tissue culture Medium 199 containing leucine-4,5-3H. Aliquots from pituitary gland homogenates and incubation medium were subjected to polyacrylamide gel electrophoresis and the optical density and radioactivity in the protein bands measured. The synthesis of hormones was observed for varying time periods up to 21 hr. Labeled prolactin appears in the medium promptly and is not retained in the gland, whereas growth hormone is largely retained in the gland. Both hormones are synthesized at comparable rates. Glands from rats with tumors MtTW5, StW5 or 7315a synthesized prolactin at a rate approximately 50% that found in control glands. No change in the pattern of prolactin release was found in glands from tum...
TL;DR: It was found that the bone weight loss and cortical area reduction caused by immobilization were reduced by electric field treatments.
TL;DR: In birds whether the myotome extends in ventro-lateral direction by growth and migration of existing cells (Engert, 1900; Williams, 1910) or by differentiation of locally found mesoderm cells into myoblasts remains even at present a controversial issue.
Abstract: Considerable difference of opinion exists about the origin of the various components of the somite. According to Williams (1910), Hamilton (1952) and Boyd (1960), the cells of the myotome originate in the dorso-medial angle of the somite wall and migrate beneath the dermatome in ventro-lateral direction. A group of older investigators (Remak, 1855; His, 1888; Bardeen, 1900) state, however, that the myotome cells originate not only in the dorso-medial angle but also along the total length of the dorsal somite wall, formed by the dermatome. Similarly, in birds whether the myotome extends in ventro-lateral direction by growth and migration of existing cells (Engert, 1900; Williams, 1910) or by differentiation of locally found mesoderm cells into myoblasts (Straus & Rawles, 1953) remains even at present a controversial issue.
TL;DR: In this paper, the authors measured the cross sections for charge transfer between positive ions and atoms and molecules in the low energy range (1 to 100 eV) using direct-current techniques for slow-product-ion detection.
Abstract: Cross sections for charge transfer between positive ions and atoms and molecules have been measured in the low-energy range (1 to 100 eV), using direct-current techniques for slow-product-ion detection. The electrode configuration adopted is designed to discriminate against elastically scattered primary particles. Resonant symmetric systems such as ${\mathrm{He}}^{+}$+He and ${\mathrm{Ar}}^{+}$+Ar and near-resonant pairs like ${\mathrm{He}}^{+}$+${\mathrm{N}}_{2}$ and ${\mathrm{He}}^{+}$+${\mathrm{O}}_{2}$, respectively, have been investigated. Cross-section functions for the symmetric cases conform to an expression of the form ${\ensuremath{\sigma}}^{\frac{1}{2}}=a\ensuremath{-}b\mathrm{ln}E$. Other reactions studied include ${\mathrm{Ar}}^{+}$ in ${\mathrm{N}}_{2}$ and ${\mathrm{H}}_{2}$ and the inverse reactions ${\mathrm{Ar}}^{+}$+He and ${\mathrm{He}}^{+}$+Ar, respectively. Results are compared with existing literature values.
TL;DR: The early manifestations of multiple sclerosis (hSS) are seldom directly observed, and their characterization therefore has been open to some question because of the inevitable dependence upon the patient’s memory of events often years past, which would afford a better opportunity to describe the onset of hfS as it occurs in the general (male) population.
Abstract: The early manifestations of multiple sclerosis (hSS) are seldom directly observed, and their characterization therefore has been open to some question because of the inevitable dependence upon the patient’s memory of events often years past. Furthermore, being drawn from hospital or clinic files, most series may well be overweighted with severe cases. In contrast, the experience of a screened military population provided with complete medical care would seem to afford a better opportunity to describe the onset of hfS as it occurs in the general (male) population. A diagnosis of ASS was cause for rejection from service. When on active duty, any symptomatology interfering with military activities led to early hospitalization. Whenever there was a suspicion of MS, neurologic evaluation followed, since this diagnosis was grounds for medical discharge from service. For these reasons, we have been seeking information on the natural history of MS on the basis of the U. S. Army experience in World War 11. The general design of the study (Nagler et al. 1966), an assessment of optic neuritis ( K u r l a n d et al. 1966), and the epidemiologic features (Beebe et al. 1967) have thus far been published. In this paper, the first on the
TL;DR: Preliminary results indicate that the technique of scanning gel chromatography is well suited for studies of interacting systems of macromolecules.
TL;DR: It is concluded that in cockroaches the gonadotropic hormone of the corpora allata is responsible for the synthesis and release into the haemolymph of proteins and possibly other nutrients as well as for the transport of these nutrients through the follicular epithelium into the oocytes.
TL;DR: In this article, a shutter was positioned between source and substrate so that cobalt deposits in which there were thickness gradients were obtained, and examination of the thin cobalt films while they were attached to their nickel substrates revealed that they were f.c.p.
TL;DR: A modification of the area-length method is described that simplifies considerably the calculations without altering the final result of left ventricular volumes measurements.
Abstract: Left ventricular volumes were measured by angiocardiography in 66 patients using different biplane and single plane methods. Regression formulae were calculated so that single plane equipment might be better utilized for volume measurements. A modification of the area-length method is described that simplifies considerably the calculations without altering the final result. A simple method of calculating LV mass is also presented.
TL;DR: Lens development in normal and mutant embryos is the same until day 14 of gestation, when anterior polar cataracts develop: the epithelial cells proliferate to form multiple layers of atypical cells, surrounded by lens capsule-like material.
Abstract: Mice carrying the gene “Shrivelled, ” also known as “Cataract-Fraser” or “Cataracta hereditaria subcapsularis, ” invariably develop lens opacities which are visible when the animals open their eyes on the fourteenth postnatal day.
Lens development in normal and mutant embryos is the same until day 14 of gestation. At this stage the nuclei of the lens fibers in the controls are large and vesicular with prominent nucleoli. In the mutants the centrally located nuclei are smaller and darker with indistinct nucleoli. The nuclei of normal fibers remain large and open even after birth; those in the mutants continue to undergo pyknosis after passing through the equatorial zone in the regular fashion. The nuclear degeneration is followed, with a delay of about 24–48 hours, by swelling and vacuolization of the fibers concerned. In the adult the lens core forms an amorphous eosinophilic mass or may partly be resorbed. The cortical fibers remain normal. Anterior polar cataracts develop: the epithelial cells proliferate to form multiple layers of atypical cells, surrounded by lens capsule-like material.
The fiber degeneration may be caused by precocious cessation of protein synthesis after the cell nucleus becomes defunct. The late epithelial aberrations may be secondary to the changes in the underlying fibers and are possibly related to the reactivation of cell replication in the central part of lens epithelium seen after traum.