bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling the early age behaviour of a low heat concrete bulkhead sealing an underground tunnel
Authors: Didry Olivier , Gray Malcolm N , Cournut André , Graham James
Published: April 2011

A major experiment - the tunnel sealing experiment, related to the disposal of heat generating radioactive wastes in geological formations and supported by government organizations from Japan, France, U.S.A., and Canada, is being carried out at the Underground Research Laboratory of Atomic Energy of Canada Limited in Manitoba, Canada. Through a systematic process, the results from the experiment will be used to validate numerical models for the early age behaviour of high mass concrete bulkheads. A numerical model, based on the CESAR-LCPC finite element code equipped with the modules TEXO and MEXO, has been developed and used to predict the behaviour of a concrete bulkhead which will be built as part of the experiment. The TEXO-based component of the model which describes temperature changes has been validated. A maximum temperature rise in the concrete of 19°C is calculated. This will occur about 4 days after the concrete is cast. The temperature rise is low. This arises from the use of a specially developed low cement content concrete. Despite uncertainties in the MEXO-based model, which is used to describe the chemo-mechanical behaviour of the system, results indicate that it is unlikely that the concrete will crack, but a gap of 0.5 mm or more will develop between the bulkhead and the rock. Water leakage around the bulkhead through this gap could be significant and measures to seal this gap are advised. The modelling results recorded here will be tested against measurements made in the experiment. Thus, the numerical model will be formally validated and bounds to its use will be defined. Key words: concrete, bulkhead, sealing, early age behaviour, heat of hydration, autogenous shrinkage, underground repository, modelling.
Tamoxifen inhibits phorbol ester stimulated osteoclastic bone resorption: An effect mediated by calmodulin
Authors: Williams John P , McKenna Margaret A , Thames III Allyn M , McDonald Jay M
Published: April 2011

Tamoxifen inhibits bone resorption by disrupting calmodulin-dependent processes. Since tamoxifen inhibits protein kinase C in other cells, we compared the effects of tamoxifen and the phorbol ester, phorbol myristate acetate, on osteoclast activity. Phorbol esters stimulate bone resorption and calmodulin levels four-fold (k0.5= 0.10.3 µM). In contrast, tamoxifen inhibited osteoclast activity ~60% with an IC50of 1.5 µM, had no apparent effect on protein kinase C activity in whole-cell lysates, and reduced protein kinase Cα recovered by immunoprecipitation 75%. Phorbol esters stimulated resorption in a time-dependent manner that was closely correlated with a similar-fold increase in calmodulin. Protein kinase Cα, β, δ, ε, and ζ were all down-regulated in response to phorbol ester treatment. Tamoxifen and trifluoperazine inhibited PMA-dependent increases in bone resorption and calmodulin by 85 ± 10%. Down-regulation of protein kinase C isoforms by phorbol esters suggests that the observed increases in bone resorption and calmodulin levels are most likely due to a mechanism independent of protein kinase C and dependent on calmodulin. In conclusion, the data suggest that protein kinase C negatively regulates calmodulin expression and support the hypothesis that the effects of both phorbol esters and tamoxifen on osteoclast activity is mediated by calmodulin.Key words: osteoclast, calmodulin, tamoxifen, osteoporosis, protein kinase C.
Isolation and characterization of a xylose-glucose isomerase from a new strainStreptomyces thermovulgaris127, var. 7-86
Authors: Raykovska Vessela , Dolashka-Angelova Pavlina , Paskaleva Donka , Stoeva Stanka , Abashev Juri , Kirkov Lubo , Voelter Wolfgang
Published: April 2011

A thermostable D-xyloseglucose isomerase was isolated from the thermophilic strain Streptomyces thermovulgaris 127, var. 7-86, as a result of mutagenic treatment by γ-irradiation of the parent strain, by precipitation and sequential chromatographies on DEAESephadex A50, TSK-gel, FPLC-Mono Q/HR, and Superose 12 columns. The N-terminal amino acid sequence and amino acid analysis shows 7392% homology with xyloseglucose isomerases from other sources. The native molecular mass, determined by gel filtration on a Superose 12 column, is 180 kDa, and 44.6 and 45 kDa were calculated, based on amino acid analysis and 10% SDS-PAGE, respectively. Both, the activity and stability of the enzyme were investigated toward pH, temperature, and denaturation with guanidine hydrochloride. The enzyme activity showed a clear pH optimum between pH 7.2 and 9.0 with D-glucose and 7.4 and 8.3 with D-xylose as substrates, respectively. The enzyme is active up to 6085°C at pH 7.0, using D-glucose, and up to 5060°C at pH 7.6, using D-xylose as substrates. The activation energy (Ea= 46 kJ·mol1) and the critical temperature (Tc= 60°C) were determined by fluorescence spectroscopy. Tcis in close coincidence with the melting temperature of denaturation (Tm= 59°C), determined by circular dichroism (CD) spectroscopy. The free energy of stabilization in water after denaturation with Gdn.HCl was calculated to be 12 kJ·mol1. The specific activity (kmvalues) for D-xylose-glucose isomerase at 70°C toward different substrates, D-xylose, D-glucose, and D-ribose, were determined to be 4.4, 55.5, and 13.3 mM, recpectively.Key words: D-xylose-glucose isomerase, protein sequencing, protein stability, protein denaturation.
His-391 of β-galactosidase (Escherichia coli) promotes catalyes by strong interactions with the transition state
Authors: Huber Reuben E , Hlede Isabel Y , Roth Nathan J , McKenzie Kyle C , Ghumman Kiran K
Published: April 2011

His-391 of β-galactosidase (Escherichia coli) was substituted by Phe, Glu, and Lys. Homogeneous preparations of the substituted enzymes were essentially inactive unless very rapid purifications were performed, and the assays were done immediately. The inactive enzymes were tetrameric, just like wild-type β-galactosidase and their fluorescence spectra were identical to the fluorescence spectrum of wild-type enzyme. Analyses of two of the substituted enzymes that were very rapidly purified to homogeneity and rapidly assayed while they were still active (at only a few substrate concentrations so that the data could be rapidly obtained), showed that the kinetic values were very similar to the values obtained with the same enzymes that were only partially purified. This showed that the kinetics were not affected by the degree of purity and allowed kinetic analyses with partially purified enzymes so that large numbers of points could be used for accuracy. The data showed that His-391 is a very important residue. It interacts strongly with the transition state and promotes catalysis by stabilizing the transition state. Activation energy differences (ΔΔGs), as determined by differences in the kcat/Kmvalues, indicated that substitutions for His-391 caused very large destabilizations (22.8-35.9 kJ/mol) of the transition state. The importance of His-391 for transition state stabilization was confirmed by studies that showed that transition state analogs are very poor inhibitors of the substituted enzymes, while inhibition by substrate analogs was only affected in a small way by substituting for His-391. The poor stabilities of the transition states caused significant decreases of the rates of the glycolytic cleavage steps (galactosylation, k2). Degalactosylation (k3) was not decreased to the same extent.Key words: β-galactosidase, mechanism, transition state, binding, histidine, catalysis.
Expression of tenascin-C by human endometrial adenocarcinoma and stroma cells: heterogeneity of splice variants and induction by TGF- b
Authors: Vollmer Günter , Tan Marselina I , Wünsche Winfried , Frank Kirsten
Published: April 2011

Localization of tenascin-C in vivo and cell culture experiments in vitro have provided evidence for stromal production of tenascin-C in malignant tumors of a variety of organs. Here we raised the question of whether the mesenchymal stroma in the case of endometrial adenocarcinoma is the unique source of tenascin-C. Therefore, the expression of tenascin-C mRNA by human endometrial adenocarcinoma cells and endometrial stroma cells was investigated. Several preparations of endometrial stroma cells produced tenascin-C mRNA. Using a serum-free defined cell culture medium, production of tenascin-C mRNA could be increased by adding either serum or 20 ng TGF- beta /mL to the cell culture medium. Reverse transcriptase polymerase chain reaction analysis revealed that five out of six endometrial adenocarcinoma cell lines produced tenascin-C mRNA. Northern blot experiments and ribonuclease protection assays provided evidence that the number of copies of tenascin-C mRNA was small. Analysis of expressed splice variants by reverse transcriptase polymerase chain reaction analysis revealed the abundance of one major splice variant that lacked all potential alternatively spliced fibronectin type-III-like repeats. Regarding larger splice variants, all fragment sizes that could theoretically originate from seven alternatively spliced fibronectin type-III-like repeats were observed. Evaluating relative signal intensities, the splice variants containing a single fibronectin type-III-like repeat and the variant possessing all but one alternatively spliced repeats were most frequent. In summary, evidence is provided that tenascin-C can originate from both tissue compartments of the human endometrium stroma and (tumor) epithelium. Splice variant analysis revealed a high number of splice variants and a relative high proportion of variants that have so far been regarded as minor constituents of expressed tenascin-C. Key words: gene expression, splice variant analysis, extracellular matrix, endometrial cancer, growth factors.
Cellular phenotypic transformation during early embryogenesis: a role for focal adhesion kinase?
Authors: Ridyard M S , Sanders E J
Published: April 2011

We have used the gastrulating chick embryo as a model for studying the potential role of focal adhesion kinase (FAK) in phenotypic transformation. In the gastrulating embryo, there is a well-defined epithelial to mesenchymal transformation as the upper epithelial epiblast layer of cells ingresses at the primitive streak to form the invasive mesenchymal mesoderm layer and the epithelioid endoderm layer. Immunolocalization showed that FAK was expressed primarily in the apical cytoplasm of the epiblast layer, together with some regions of the mesoderm and endoderm. Hensen's node and the primitive streak, where the transformation occurs, showed very low immunoreactivity. Levels of FAK in these individual tissues were quantified by densitometric analysis of Western blots, and FAK activation was quantified by stripping these blots and reprobing for phosphotyrosine. Immunoprecipitation indicated that the phosphotyrosine bands corresponded with the FAK bands on the blots. Although the blots confirmed that FAK was highly expressed in the epiblast, the level of FAK activation was highest in the endoderm, despite relatively low expression of the protein. Similar quantitative blotting was carried out using cells from each of the three layers cultured on different substrata. The results indicated that cells cultured on fibronectin, laminin, and Matrigel expressed differing levels of FAK, with differing levels of tyrosine phosphorylation, depending on the cell type and the substratum. We conclude that FAK is developmentally regulated during gastrulation, and that this regulation could be influenced by the changing substratum encountered by the differentiating cells during this process. However, the apical localization of FAK in much of the epiblast appears to preclude a consistent focal contact-like association of this molecule with integrins in vivo, and we therefore suggest that in the embryo, FAK may be involved in integrin-mediated signalling pathways without physical association with cell-substratum contacts.Key words: chick, embryo, gastrulation, phenotypic transformation, FAK.
Heat shock-induced acquisition of thermotolerance at the levels of cell survival and translation inXenopusA6 kidney epithelial cells
Authors: Phang Donna , Joyce Elizabeth M , Heikkila John J
Published: April 2011

In this study we have investigated the acquisition of thermotolerance in a Xenopus laevis kidney A6 epithelial cell line at both the level of cell survival and translation. In cell survival studies, A6 cells were incubated at temperatures ranging from 22 to 35°C for 2 h followed by a thermal challenge at 39°C for 2 h and a recovery period at 22°C for 24 h. Optimal acquisition of thermotolerance occurred at 33°C. For example, exposure of A6 cells to 39°C for 2 h resulted in only 3.4% survival of the cells whereas prior exposure to 33°C for 2 h enhanced the survival rate to 69%. This state of thermotolerance in A6 cells was detectable after 1 h at 33°C and was maintained even after 18 h of incubation. Cycloheximide inhibited the acquisition of thermotolerance at 33°C suggesting the requirement for ongoing protein synthesis. The optimal temperature for the acquisition of translational thermotolerance also occurred at 33°C. Treatment of A6 cells at 39°C for 2 h resulted in an inhibition of labeled amino acid incorporation into protein which recovered to approximately 14% of control after 19 h at 22°C whereas cells treated at 33°C for 2 h prior to the thermal challenge recovered to 58% of control levels. These translationally thermotolerant cells displayed relatively high levels of the heat shock proteins hsp30, hsp70, and hsp90 compared to pretreatment at 22, 28, 30, or 35°C. These studies demonstrate that Xenopus A6 cells can acquire a state of thermotolerance and that it is correlated with the synthesis of heat shock proteins.Key words: Xenopus laevis, heat shock protein, hsps, A6 cells, chaperone, thermotolerance.
DNA-induced conformational change of Gaf1, a novel GATA factor inSchizosaccharomyces pombe
Authors: Won Misun , Hoe Kwang-Lae , Cho Yong-Sik , Song Kyung Bin , Yoo Hyang-Sook
Published: April 2011

A novel GATA factor in Schizosaccharomyces pombe, Gaf1, containing one zinc-finger motif was studied for conformational change that was induced by DNA-binding. Gaf1 was shown to bind to the upstream activation sequence of a gene in Saccharomyces cerevisiae containing GATA element by gel mobility shift assay. Circular dichroism spectra of Gaf1 indicated an increase of alpha-helix content of Gaf1 occurred upon binding to the upstream activation sequence. These results suggest that the binding of Gaf1 to the GATA element is required for the conformational change that may precede transactivation of the target gene(s).Key words: GATA factor, Schizosaccharomyces pombe, DNA-binding, conformational change.
Identification of theEscherichia colienzyme I binding site in histidine-containing protein, HPr, by the effects of mutagenesis
Authors: Brokx Stephen J , Napper Scott , Wong George , Mirza Ahmad , Georges Fawzy , Delbaere Louis TJ , Waygood E Bruce
Published: April 2011

The structure of the N-terminal domain of enzyme I complexed with histidine-containing protein (HPr) has been described by multi-dimensional NMR. Residues in HPr involved in binding were identified by intermolecular nuclear Overhauser effects (Garrett et al. 1999). Most of these residues have been mutated, and the effect of these changes on binding has been assessed by enzyme I kinetic measurement. Changes to Thr16, Arg17, Lys24, Lys27, Ser46, Leu47, Lys49, Gln51, and Thr56 result in increases to the HPr Kmof enzyme I, which would be compatible with changes in binding. Except for mutations to His15 and Arg17, very little or no change in Vmaxwas found. Alanine replacements for Gln21, Thr52, and Leu55 have no effect. The mutation Lys40Ala also affects HPr Kmof enzyme I; residue 40 is contiguous with the enzyme I binding site in HPr and was not identified by NMR. The mutations leading to a reduction in the size of the side chain (Thr16Ala, Arg17Gly, Lys24Ala, Lys27Ala, and Lys49Gly) caused relatively large increases in Km(>5-fold) indicating these residues have more significant roles in binding to enzyme I. Acidic replacement at Ser46 caused very large increases (>100-fold), while Gln51Glu gave a 3-fold increase in Km. While these results essentially concur with the identification of residues by the NMR experiments, the apparent importance of individual residues as determined by mutation and kinetic measurement does not necessarily correspond with the number of contacts derived from observed intermolecular nuclear Overhauser effects.Key words: Phosphoryl transfer; enzyme I; phosphoenolpyruvate-sugar phosphotransferase system; HPr; protein-protein interaction.
THE ANGULAR CORRELATION OF ANNIHILATION RADIATION
Authors: Argyle P. E. , Warren J. B.
Published: April 2011

The angular distribution of annihilation radiation from copper 64 has been measured with a pair of scintillation counters in coincidence. Coincidences were found when the counters and source were not quite collinear. The relation between the noncollinear coincidence rate and angle of deviation λ could be closely approximated to by an exponential of the form [Formula: see text], where λ0 = (3.60 ± 0.04) 10−3 radian. Interpreting this departure from antiparallelism of the two photons as arising from the residual motion of the annihilating pair, the average momentum of their mass center in copper is found to be (7.20 mc.) × 10−3 which corresponds to an electron energy of 13.2 ev., if the positron is assumed to be thermalized before annihilation.
THE PRECISION MEASUREMENT OF HALF LIVES OF RADIOACTIVE SUBSTANCES
Authors: Silver Lorna M.
Published: April 2011

A vibrating reed electrometer with feedback amplifier has been used in conjunction with a differential ionization chamber to measure accurately the decay periods of several radioactive isotopes. This method proved to be simple, reliable, and free from uncertain corrections, with a low background due to the differential technique adopted and a low drift rate (normally less than 5 × 10−17 amp.) due to the feedback electrometer circuit. This high and easily varied sensitivity enabled the decay to be followed over 12 periods, making possible the detection of, and correction for, any weak long lived impurity activity, thus eliminating one major source of error in half life measurements. Least squares analysis of the data showed that a quadratic mean error as small as 1/2% can be easily achieved with this apparatus. Half life values were found as follows:[Formula: see text]
ON θ VALUES IN METALS. II
Authors: Kelly F. M.
Published: April 2011

The four methods of calculating θD, the Debye characteristic temperature for specific heats, and θR, the characteristic temperature which appears in the quantum theory of electrical resistance, discussed in a previous paper, are applied to copper, silver, and gold. An allowance has also now been made for the variation of electrical resistance with volume to take into account the effects of thermal expansion before θR is calculated and compared with θD. Revised values of θR for lithium and sodium are given.
THE EFFECT OF SUNRISE ON THE REFLECTION HEIGHT OF LOW FREQUENCY WAVES
Authors: Brown S. B. , Petrie W.
Published: April 2011

It has been found that when radio waves of frequency 16 kc./s. and somewhat higher are transmitted over distances of 540 km., the phase and amplitude of the received signal change suddenly about one hour before ground sunrise at the mid-point of the transmission path. This effect results from a lowering of the nighttime reflection height of 95 km. to the daytime value of 70 km.By considering the geometry of the situation, it is apparent that the process of photo-ionization of atmospheric molecules cannot produce the observed effect since the relevant wave lengths are absorbed before reaching the 95 km. height. On the other hand, electrons may be removed from negative oxygen ions by visible and near infrared radiation which does reach the 95 km. level prior to sunrise. The problem is then to determine the intensities of the relevant wave lengths at the 95 km. level, and to compute the rate at which electrons are released from negative ions. It is shown that the pre-sunrise effect at 95 km. is readily explained as a negative ion phenomenon, and the rate of fall of reflection height is discussed.
A METHOD OF DETERMINING THE ELECTRONIC TRANSITION MOMENT FOR DIATOMIC MOLECULES
Authors: Fraser P. A.
Published: April 2011

A method is described that will give the variation, as a function of internuclear distance, of the electronic transition moment governing intensities in diatomic molecular band systems. Reliable theoretical results and good experimental intensities are used conjointly to find this variation. Once smoothed, the trend may be replaced into the overlap integrals to give relative vibrational transition probabilities better than those given by the approximation ‘overlap integrals squared’, and presumably better than those deduced directly from experiment, since the latter are not smoothed. Limits on the application of the method are suggested; however many band systems fall within these limits.
THE FISSION YIELDS OF THE STABLE AND LONG-LIVED ISOTOPES OF XENON, CESIUM, AND KRYPTON IN NEUTRON FISSION OF U233
Authors: Fleming W. , Tomlinson R. H. , Thode H. G.
Published: April 2011

The fission yields of Xe131, Xe132, Xe134, Xe136, Cs133, Cs135, Cs137, Kr83, Kr84, 10.27 year Kr85, and Kr86 in the neutron fission of U233 have been determined by mass spectrometer methods. The very pronounced fine structure in the mass yield curve in the mass range 131 to 137 found in U235 fission does not occur in the fission of U233. This disappearance of fine structure would not have been predicted by any of the mechanisms which have been suggested to explain the fine structure in U235 fission. The fission yield of the 10.27 year isomer of Kr85 relative to the other krypton isotopes is considerably higher in U233 fission than in U235 fission, indicating some fine structure in this mass range which may be related to the closed shell of 50 neutrons.
A POTENTIAL FUNCTION FOR LIQUID HELIUM AT 0°K.
Authors: Beaumont C. F. A.
Published: April 2011

A new potential function for liquid helium is obtained by modifying the Margenau potential function and summing over a suggested structure for the liquid. The new potential function leads to fair agreement with the first peak of the radial distribution curve for liquid helium, with the isothermal compressibility, and with second virial coefficient data at high temperatures.
THE EFFECT OF HIGH LOADING ON THE KINETIC FRICTIO OF ICE
Authors: Niven C. D.
Published: April 2011

The kinetic friction of stainless steel on ice decreased very markedly at high loadings of 30 to 50 kgm. Per sq. cm. This constituted a violation of Amontons' Law. At low loading the material of a slider is of far greater importance than at high loading, which suggests that in the explanation of the friction of ice at least two important factors are involved, which are related respectively to (a) pressure and (b) adhesion.
MOTION OF CLOUDS OF ABNORMAL IONIZATION IN THE AURORAL AND POLAR REGIONS
Authors: Hagg E. L. , Hanson G. H.
Published: April 2011

Examination of records taken in rapid succession at ionospheric stations in Northern Canada has revealed three distinctive types of echoes corresponding to clouds of ionization in motion. One type is ascribed to clouds of sporadic E moving horizontally over the station. The second type is believed to be due to clouds of ionization descending vertically from the F region to the E region, while the third type appears to be from clouds moving at extremely high velocities in the E region. Reflections of the second and third types have been seen only at stations in or north of the auroral zone. The characteristics of the echoes, the velocities of the clouds, and other associated phenomena are discussed.
A CALORIMETRIC DETERMINATION OF THE AVERAGE KINETIC ENERGY OF THE FRAGMENTS FROM U235 FISSION
Authors: Leachman R. B. , Schafer W. D.
Published: April 2011

The average heat of thermal-neutron induced fission of U235 has been measured by a differential calorimeter. The average energy per fission observed by the calorimeter was 170.1 ± 1.2 Mev. On the basis of the thicknesses of the calorimeter materials and the theoretical energy loss equation, the β energy per fission observed by the calorimeter is 3.0 ± 1 Mev. and, on the same basis, the γ and neutron energy observed is negligible. The resulting 167.1 ± 1.6 Mev. for the average kinetic energy of the fission products is shown to be in good agreement with less direct determinations of this quantity.
DIFFRACTION OF MICROWAVES BY LONG METAL CYLINDERS
Authors: Adey Albert W.
Published: April 2011

A parallel-plate transmission line has been applied to the study of the amplitude and phase of the diffracted electric field near metal cylinders of circular, square, and rectangular cross-section. The transverse dimensions of the cylinders are comparable with the wavelength (3.280 cm.). A travelling dipole probe inserted in the line through a slot in one of the plates permits investigation of the field. Absorbing wedges at the boundary of the line make the plates effectively infinite in extent. Essentially plane wave conditions exist in the region utilized in the measurements. Good agreement is obtained between calculation and experiment for circular cylinders. Measured results are given for square and rectangular cylinders. For one orientation of the rectangles the measured results are compared with approximate calculations.
CAPTURE RADIATION AND NEUTRONS FROM THE BOMBARDMENT OF C14 WITH PROTONS
Authors: Bartholomew G. A. , Brown F. , Gove H. E. , Litherland A. E. , Paul E. B.
Published: April 2011

The yield and angular distribution of ground state γ-rays and of neutrons resulting from the proton bombardment of C14 have been studied for proton energies from 0.2 to 2.5 Mev. Assignments of spin and parity are made to most of the resonances observed in this range. A single particle proton state which may have isotopic spin 3/2 has been observed. The interference of this state, which has spin 1/2+, with a neighboring state of the same spin and parity is observed in the total yield of the ground state γ-ray. Three states below the neutron threshold which have been observed previously in the N14(d, p)N15 reaction are also observed in the C14(p, γ)N15 reaction. The N14(n, p)C14 cross section at thermal energies can be accounted for by a resonance observed in this experiment, but another resonance below the neutron threshold must be assumed to account for the thermal (n, n) and (n, γ) cross sections.
RADIO STAR SCINTILLATIONS AND THE IONOSPHERE
Authors: Hartz T. R.
Published: April 2011

The observed intensity at the surface of the earth of radiation at a frequency of 50 Mc./s. from a radio star has been studied. A relationship is shown to exist between the fluctuations, or scintillations, in this observed radiation intensity and the angle of its incidence on the 400 km. level of the earth's ionosphere. The occurrence of these scintillations is compared with other ionospheric phenomena as determined by vertical soundings from the earth. The probable cause of the fluctuations has been localized to a source in the high ionospheric regions.
FIELD EQUATIONS FROM PARTICLE EQUATIONS
Authors: Archibald W. J.
Published: April 2011

A simple point of view is developed which shows how various types of field equations may be obtained from the relativistic Hamiltonian of a particle.
RANGE-ENERGY RELATIONS FOR LIGHT NUCLEI IN AIR AND NUCLEAR EMULSION
Authors: Livesey D. L.
Published: April 2011

An empirical method has been developed for estimating the effective charge of ions between Z = 3 and Z = 10 over a wide range of velocities in air and nuclear emulsion. The results are used in conjunction with a power-law function for the variation of stopping-power with velocity to derive range–energy relations for these ions. The curves are compared with all available experimental data, and agreement within the limits of experimental error is obtained in all cases except those of fluorine and neon ions in air.
ON THE EFFECT OF SPEED ON THE KINETIC FRICTION OF SOME PLASTIC MATERIALS ON ICE
Authors: Niven C. D.
Published: April 2011

Curves are shown illustrating the effect of speed on the friction of teflon, bakelite, nylon, terylene, plexiglas (perspex), cellulose acetate, polystyrene, and polyethylene, sliding on ice at −5 °C. and −15 °C. Bakelite and teflon had the lowest kinetic friction of the materials examined. Terylene also slid easily but polyethylene had rather high friction. Departure from Amontons' Law was very evident at high speed.
THE RELATIONSHIP BETWEEN THE STATISTICAL AND FIELD THEORETICAL TREATMENTS OF MULTIPLE MESON PRODUCTION
Authors: Takahashi Yasushi
Published: April 2011

The aim of this note is to point out the relation between Fermi's statistical theory of multiple meson production and the field theoretical treatment.
PHOTO ALPHA REACTIONS IN SILVER
Authors: Roalsvig J. P. , Haslam R. N. H. , Skarsgard L. D. , Wuschke E. E.
Published: April 2011

The reaction Ag109(γ, α)Rh105 has been investigated by using the secondary activity of Rh105. Statistical theory was used to obtain information about the reactions Ag107(γ, α)Rh103 and Ag(γ, α) Rh. The present values for the absolute yield and cross section are in agreement with previous work using either the secondary activity or photographic plates.
THE SUPERCONDUCTING TRANSITION IN POLYCRYSTALLINE TIN
Authors: Aziz R. A. , Baird D. C.
Published: April 2011

The influence of grain size on the breadth of the superconducting transition in polycrystalline tin has been studied. The transition has been detected using an a-c. induction method. A range of grain sizes from 0.2 mm to 10 mm was used and the corresponding range in transition breadth is from 75 to 18 millidegrees. The influence of the grain boundaries is to broaden all the transition curves towards higher temperatures from a well-defined end point which is common to all the curves.
CENTRAL THREE-BODY FORCES IN HEAVY NUCLEI
Authors: Smith Robert C. , Sharp Robert T.
Published: April 2011

Three-nucleon potentials are calculated using the renormalized, static theory of Chew and Low. These potentials are used to evaluate the three-body contribution to the total energy per nucleon in nuclear matter as a function of nuclear density. It is found that while the three-body energy is greater than that predicted by unrenormalized theories by about one order of magnitude as a result of multiple-scattering effects, its dependence on the nuclear density in the region of the equilibrium density is very weak. Three-body forces are therefore not expected to change the saturation properties of nuclear matter as predicted by a hard core potential to any appreciable extent.
ON THE TEMPERATURE DEPENDENCE OF THE SHAPE OF PARAMAGNETIC RESONANCE LINES
Authors: McMillan Malcolm , Opechowski W.
Published: April 2011

A theory of the temperature dependence of the shape of paramagnetic resonance lines is developed for temperatures sufficiently low to make the effects of the spin–lattice interaction and thermal expansion negligible. General expressions for the first and second moments of the line shape function as functions of the temperature are obtained, and the approximations used are discussed in detail. These expressions are applied to the case of effective spin [Formula: see text] and 1. As an illustration of the general theory numerical results are given for the paramagnetic resonance lines of nickel fluosilicate. In this case the moments become strongly temperature dependent below 10 °K.
ON BOURRET'S HYPOTHESIS CONCERNING TURBULENT DIFFUSION
Authors: Roberts P. H.
Published: April 2011

An integrodifferential equation proposed on heuristic grounds by Bourret for turbulent diffusion is compared with a similar equation which was derived by Roberts from the application of Kraichnan's approximation to the exact equations of turbulent diffusion, and which is itself closely related to an equation postulated by Bourret as a result of further heuristic arguments. A simple generalization of Taylor's model of turbulent diffusion is discussed, and is found to obey Roberts' equation but, unless the spacial correlation between the velocity of the diffusing particles is zero, it does not obey the equation initially proposed by Bourret.
THE ABSORPTION SPECTRA OF HNO AND DNO
Authors: Bancroft J. L. , Hollas J. M. , Ramsay D. A.
Published: April 2011

The long wavelength 1A″ – 1A′ transition of HNO and DNO has been studied in absorption under high resolution using much greater absorption intensities than in the earlier work of Dalby. Seven new bands of HNO and six new bands of DNO have been found and analyzed. Values for [Formula: see text] have been found and are: [Formula: see text] and [Formula: see text]. Equilibrium rotational constants [Formula: see text], [Formula: see text], and [Formula: see text] have been determined for both molecules. The values for HNO give zero inertial defect but the values for DNO are less satisfactory, presumably due to resonance between pairs of levels (1, [Formula: see text], [Formula: see text]) and (0, [Formula: see text], [Formula: see text]). Equilibrium values for the geometrical parameters of the excited state have been evaluated and are: [Formula: see text] [Formula: see text], [Formula: see text].Some of the rotational lines of the (101)–(000) band of HNO are found to be slightly diffuse, the maximum observed line width being ~0.7 cm−1. This observation confirms the predissociation limit found in the emission studies of Clement and Ramsay and gives a value for the lifetime of the molecule in the excited state, viz τ ~7.6 × 10−12 sec. The predissociation is weak and the possible states causing this predissociation are discussed.
ON THE QUANTUM MECHANICAL GENERALIZATION OF BLOCH'S TRANSPORT EQUATION
Authors: Hajdu J.
Published: April 2011

A simple derivation is given of a kinetic equation for a system of free electrons moving in uniform electric and magnetic fields, and interacting with fixed scattered. The kinetic equation describes the asymptotic behavior of the single-electron density operator if it approaches a steady value, or the asymptotic behavior of its average over oscillations if the density operator oscillates in time. This equation, which is effectively the quantum mechanical generalization of Bloch's transport equation, is identical with the one recently derived by Kosevich and Andreev using Bogolyubov's method. More general considerations show that this asymptotic equation is valid, and describes the approach to the steady state for weak magnetic fields when the relaxation time is much longer than the atomic time. For strong magnetic fields, the same statement holds if the density operator is averaged over its oscillations, whereas the unaveraged approach towards the steady state is governed by a somewhat different equation. The solutions of these two equations become identical in the most important limiting cases. The results obtained previously by different authors follow from the kinetic equation when further assumptions are introduced.
EFFECTS OF THE GROUND ON THE γ DOSE FROM DISTRIBUTED 137Cs SOURCES
Authors: Clifford C. E.
Published: April 2011

The effects on the exposure dose of different ground materials and of a ground cover similar to snow were measured for a smooth surface contaminated with 0.66-MeV γ sources (137Cs). Measurements were made also of the effect of a rough surface on the exposure dose. For uniform contamination of a smooth ground, agreement within 10% was obtained with theoretical dose distributions based on infinite-medium calculations. However, even moderate ground roughness reduced the dose at a detector height of 1 meter by a factor of two below its value for a smooth surface. Failure to specify the effect of ground roughness on smooth field calculations as a function of the surface roughness appeared to be the largest source of error in the calculation of exposure dose.
THE TOTAL NEUTRON CROSS SECTION OF 241Pu BELOW 1000 eV
Authors: Craig D. S. , Westcott C. H.
Published: April 2011

Measurements have been made of the total neutron cross section of 241Pu over the energy ranges of 0.025 eV to 0.75 eV and 13.8 eV to 1000 eV, using a specimen of PuO2 powder and one of Pu–Al alloy. The 241Pu content of the plutonium was 80%. The specimen thickness was known to 2%. The measurements were made with the B.N.L.–A.E.C.L. chopper at C.R.N.L., using resolutions up to 0.02 μsec/m. The results are given in graphical form. Resonance parameters are given for the region from 12 eV to 32 eV. When these parameters are used with the single-level Breit–Wigner formula a reasonable fit to the data is obtained.
On the orthogonality condition for the excited states of stationary quantum systems
Authors: Sharma C. S.
Published: April 2011

A theorem establishing the correct orthogonality condition for the perturbation expansions of the state vectors for the excited states of stationary quantum systems is enunciated. A common misunderstanding on this subject is discussed and corrected. Implications of the theorem to the use of the variation perturbation method for calculating approximate eigenvalues and eigenvectors for excited states is discussed.
Simultaneous observation of electron fluxes, ionization, and luminosity in an aurora
Authors: Matthews D. L. , Clark T. A.
Published: April 2011

Electron energy spectra, number density of ambient electrons, and 5577 Å luminosity have been measured in a rocket which passed through a well-defined westward-moving auroral band embedded in a widespread diffuse glow. In the band there was excellent spatial correlation among the electron number density, the luminosity as seen from both the ground and the rocket, and the electron flux of energy 1–7 keV. A peak of higher-energy electrons apparently trailed the band by ~ 10 km. The electron fluxes appeared to be not quite sufficient to account for the observed electron number density, still less for the luminosity. Fluxes of electrons having energies of the order of 100 eV were observed, too large and too uncorrelated with the higher-energy electron fluxes to be secondaries produced in the atmosphere by the electrons of higher energy. Since 100-eV electrons cannot penetrate from above to such heights [Formula: see text], there is a suggestion that they must have been locally accelerated. When these electrons are included in the calculations, it is possible under certain assumptions to obtain quantitative agreement between electron flux, electron density, and 5577 Å photon production in the diffuse glow.
Anomalous interactions of secondary particles emitted from relativistic heavy primary interactions
Authors: Judek B.
Published: April 2011

Interaction mean free paths of relativistic secondary particles emitted from interactions of heavy primary cosmic-ray nuclei in emulsions were measured. The results show that among the Be, Li, He, and singly charged secondary nuclei there are particles present which interact with a cross section several times higher than the expected geometrical value. The stars produced by these particles have the characteristics of ordinary nuclear interactions. There appears to be no interpretation of these observations in terms of any known particle phenomena.
On radiofrequency transitions and nuclear and electron polarization for hydrogen molecular ions H2+
Authors: Blicharski J. S.
Published: April 2011

Relative intensities of hyperfine transitions and nuclear and electron polarizations have been calculated for hydrogen molecular ions H2+.
Liquid helium and the properties of a Bose–Einstein gas. I. A numerical study of hard-core models
Authors: Goble D. F. , Trainor L. E. H.
Published: April 2011

The properties of a hard-sphere, Bose–Einstein gas are investigated numerically in the t-matrix, ladder approximation, using both the coordinate-space treatment of Brueckner and Sawada, as modified by Parry and ter Haar, and the pseudopotential method of Liu and Wong. For each treatment, the form of the excitation spectrum and the thermodynamic properties of the gas at low temperatures are compared with the corresponding properties of liquid helium. The pseudopotential method gives better agreement for a reasonable choice of the radius of the "hard-core" interaction. This result is not surprising since the actual potential corresponding to the pseudopotential of Liu and Wong is intermediate between the "soft-core" potential of Brueckner and Sawada and a true "hard-core" potential.
Pulsed nuclear magnetic resonance in a tin single crystal
Authors: McLachlan L. A.
Published: April 2011

Pulsed nuclear magnetic resonance studies of an isotopically pure 119Sn single crystal were made at 78 °K. An attempt to observe anisotropy in the spin–lattice relaxation time was inconclusive, but gave T1T = (34 ± 2) ms deg as the average value. Spin–spin relaxation was dominated by the pseudo-exchange interaction. The numerical value for this, (2.0 ± 0.5) kc/s, is in agreement with the value calculated from the Rudermann–Kittel theory. A strong pseudodipolar interaction was also observed.
On the pair correlation function for hard spheres at low density and temperature
Authors: Miller M. S. , Poll J. D.
Published: April 2011

A quantum-mechanical calculation of the pair correlation function for hard spheres in the low-density limit has been made. This calculation is, therefore, valid at low temperatures, where quantum-mechanical diffraction and symmetry effects are important. Results are given for various temperatures and hard-sphere diameters. The pair correlation function is presented in the form g = gB + gS, where gB is the correlation function for Boltzmann particles and gS describes the symmetry effects. It is found that gS(R) for any value of the separation R is always smaller than the corresponding value for free particles.
Covalency effect in paramagnetic relaxation
Authors: Weissfloch C. F.
Published: April 2011

The effect of covalency on the spin–lattice relaxation of an iron-group ion in octahedral coordination is examined. It is found that the covalent contribution to the spin–phonon Hamiltonian is predominantly "dipolar", but probably too small to cause a measurable violation of the quadrupolar selection rules for [Formula: see text] ions at and below JV-band frequencies. For an ion with a low-lying spin doublet, the covalent contribution could be important.
Current distribution on a thin cylindrical antenna immersed in an isotropic compressible plasma
Authors: Monroe Richard L.
Published: April 2011

An integrodifferential equation is derived for the current distribution along a thin, hollow, center-driven, cylindrical, perfectly conducting antenna immersed in an isotropic, compressible plasma. On the basis of this equation it is shown that the current distribution approaches sinusoidal form as the radius of the antenna approaches zero. The propagation constant for this current is approximately equal to the free-space wave number for most frequencies greater than the plasma frequency.
Transient radiation in a plane stratified dispersive medium. I. Half-space configuration
Authors: Ott Edward , Shmoys Jerry
Published: April 2011

In this paper a similarity principle will be derived for a class of transient diffraction problems in cold, lossless, isotropic plane stratified plasmas. The similarity principle will be utilized to obtain an exact closed-form solution to the problem of a magnetic current source whose density is a delta function (in space and time) situated either in or above a homogeneous plasma half-space. This solution will be interpreted in terms of rays and group velocity. An independent solution to the half-space problem will also be obtained using asymptotic techniques. Exact and asymptotic solutions will be compared and discussed.
Attenuation function for propagation over a nonparallel stratified ground
Authors: Schlak Gerard A. , Wait James R.
Published: April 2011

The directional dependence of the calculated surface impedance on a nonparallel stratified conductor is pointed out. In spite of this dependence, the reciprocity theorem is not violated when the mutual coupling between two dipoles is considered.
Variation of neutron yield with fragment mass in fission
Authors: Gorman D. J. , Tomlinson R. H.
Published: April 2011

A semiempirical method is developed for constructing neutron-yield curves based on Terrell's "universal" curve and the postulate of Glendenin (1949). The curves so constructed, when combined with the prompt yields, will reproduce the fine structure in the cumulative yields.
Dynamics of galactic plasma. I
Authors: Pratap R.
Published: April 2011

We propose to answer the question as to whether there could be a topological configuration of the magnetic field, velocity field, and a potential field which could retain the galactic plasma in the spiral arm in a self-consistent way. In the kinematic theory we have developed here, we do not have an external magnetic field such as an intergalactic field, but have only the internal magnetic fields generated by the motion of the plasma as such. We have applied the kinetic equations to a galactic plasma rather than the fluid equations as is usually done; and, assuming a general quadratic expression for the distribution function in the velocity space, we have looked for the complete class of self-consistent magnetic fields, potential fields, as well as density distributions. Many important features of the magnetic fields are brought out and discussed at length. It is found that the "frozen-in" condition is valid for such a low-density plasma as well (eq. [4.11]). We have also indicated the lines in which this theory could be developed further.
Energy relaxation for thermal electrons in CO
Authors: Mentzoni Michael H. , Donohoe James
Published: April 2011

Using published cross sections for rotational excitation and de-excitation caused by dipole and quadruple interactions in carbon monoxide, the average electron energy loss rate, [Formula: see text], is computed as a function of excess electron temperature, Te − T, for the case of a maxwellian velocity distribution for various gas temperatures, T. It is found that the dipole and quadrupole contributions to the loss rate are in the ratio 3:1 with the composite electron energy relaxation time given by pτ = 338 ns Torr for Tgas = 300 °K. The initial values of [Formula: see text] caused by dipole interaction decrease more rapidly with temperature than T−1/2, which was the temperature variation found in the case of quadrupole interaction. Experimentally, microwave cross-modulation results pertaining to the isothermal afterglow of a d-c. discharge in CO yielded the value pτ = 113 ± 11 ns Torr for T = 300 °K. The apparent discrepancy between theory and experiment is discussed.
Centrifugal stretching of a classical rotator and collective motions in nuclei
Authors: Sood P. C.
Published: April 2011

The energy of a classical rotator with the inclusion of the effect of centrifugal forces is calculated. The resulting set of parametric equations is found to yield an excellent description of rotational states in deformed nuclei. The formulation within the framework of the hydrodynamical model also predicts β-vibrational energies in good agreement with the observed levels. Our results are practically identical with those obtained from the Davydov–Chaban model with axial symmetry. Comparison with other models, which include the rotation–vibration interaction corrections, establishes the relative merit of our simple approach.
The dependence of the hyperfine interaction on the cellular potential in Li, Na, and K
Authors: Moore R. A. , Vosko S. H.
Published: April 2011

The effect of including the Hartree field due to the conduction electrons in the cellular potential on the Fermi surface electron wave function is investigated. It is found that the Fermi surface electron density at the nucleus is reduced by 10% to 20% by including this term. Also, an L dependent effective local potential constructed to simulate Hartree–Fock theory is calculated and applied to Li. All calculations are performed using the Wigner–Seitz spherical cellular approximation, and the Schrödinger equation is solved by the Kohn (1954) variational method.