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Articles 21841 - 21870 of 21971

Full-Text Articles in Physical Sciences and Mathematics

Adaptative Alteration In Phospholipid Composition Of Plasma Membranes From A Somatic Cell Mutant Defective In The Regulation Of Cholesterol Biosynthesis, Michael Sinensky Jan 1980

Adaptative Alteration In Phospholipid Composition Of Plasma Membranes From A Somatic Cell Mutant Defective In The Regulation Of Cholesterol Biosynthesis, Michael Sinensky

Michael Sinensky

A somatic cell mutant (CR1) of a Chinese hamster ovary cell (CHO-K1) which has previously been shown to be defective in the regulation of cholesterol biosynthesis accumulates more cholesterol than the parental cell line in plasma membranes. Although such an increase in membrane cholesterol should lead to an increase in the order parameter of these membranes, as measured with an electron spin resonance spin probe, the order parameters of mutant and wild-type plasma membranes are identical--apparently because of an adaptive alteration in membrane phospholipid composition. The phospholipid compositions of mutant and wild-type cell plasma membranes are compared and the mutant …

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Type I Radar Echoes From Theequatorial Electrojet With Double Peaked Doppler Spectra, Bela G. Fejer, D. T. Farley, P. Johnston, B. B. Balsley Jan 1980

Type I Radar Echoes From Theequatorial Electrojet With Double Peaked Doppler Spectra, Bela G. Fejer, D. T. Farley, P. Johnston, B. B. Balsley

Bela G. Fejer

Normal type 1 radar echoes obtained from relatively large zenith angles have a power spectrum with a single narrow peak whose Doppler shift corresponds approximately to the acoustic velocity in the medium. On some occasions, however, this single maximum splits into two distinct peaks, separated in phase velocity on one occasion by 270 m/s. This bifurcation is most easily observed at large zenith angles during daytime when a narrow antenna beam is used. It has also been seen in a daytime experiment in which radars at Jicamarca and Huancayo simultaneously probed the same region from two different radar zenith angles. …

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Simple Parallel Interface Between An Optical Multichannel Analyzer And A Microprocessor, Stephen E. Bialkowski Jan 1980

Simple Parallel Interface Between An Optical Multichannel Analyzer And A Microprocessor, Stephen E. Bialkowski

Stephen E. Bialkowski

A simple circuit is given which will allow data transfer from a LSI‐11 DRV11 parallel interface unit to a PARC 1216 Optical Multichannel Detector Controller. The Circuit for OMA to LSI‐11 data transfer is slightly more complicated. Data buffering is used so that data transfer can occur without time‐out loss due to the dynamic memory refresh cycle of the LSI‐11. The circuit may be constructed and mounted within the PARC 1216 unit with only minor, noncritical, modifications to the controller unit. The unit is able to transmit data from the 1216 controller running at dwell times as short as 40 …

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The Determination Of Mass Transport Coefficients And Vibrational Relaxation Rates Of Speciesformed In Laser Photolysis Experiments, Stephen E. Bialkowski, David S. King, John C. Stephenson Jan 1980

The Determination Of Mass Transport Coefficients And Vibrational Relaxation Rates Of Speciesformed In Laser Photolysis Experiments, Stephen E. Bialkowski, David S. King, John C. Stephenson

Stephen E. Bialkowski

A simple analytical solution of the equations which govern the formation, collisional relaxation, and mass transport rates of species produced in radially symmetric laser‐induced processes is given. These equations are specifically applied to the CO2 laser‐induced dissociations of CF2HCl and C2F3Cl dilute in argon. The concentration of the vibrational ground state of the CF2 radical product was probed as a function of time and pressure both during and after the photolyzing laser pulse by the laser‐excited fluorescence technique. From these measurements, the vibrational relaxation rate of ? CF2 in argon was …

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Energy Partitioning In The Ir Multiphoton Dissociation Of Molecules: Energy Of Xcf2 And Xcfcl Fromcf2Cfcl, John C. Stephenson, Stephen E. Bialkowski, David S. King Jan 1980

Energy Partitioning In The Ir Multiphoton Dissociation Of Molecules: Energy Of Xcf2 And Xcfcl Fromcf2Cfcl, John C. Stephenson, Stephen E. Bialkowski, David S. King

Stephen E. Bialkowski

We have measured the vibrational (v), rotational (J,K), and translational energy, (ET), of the X̃ CF2 and X̃ CFCl fragments formed in the CO2 laser induced multiphoton dissociation of CF2CFCl (chlorotrifluoroethylene): CF2CFCl→CF2(v,J,K)+CFCl(v,J,K)+ET(v,J,K), which was the only detectable reaction path for CF2CFCl. More vibrational energy (Ev) appears in CF2 than in CFCl. Direct spectroscopicmeasurements of populations in levels 0<ν2<7 show that Ev is distributed statistically in the bending mode (ν2) of CF2 according to P(Ev)=exp(−Ev/k Tv), …

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A Theory Of Reading: From Eye Fixations To Comprehension, Marcel Adam Just, Patricia A. Carpenter Dec 1979

A Theory Of Reading: From Eye Fixations To Comprehension, Marcel Adam Just, Patricia A. Carpenter

Marcel Adam Just

No abstract provided.

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Interpolating Functions Associated With Second Order Differential, William F. Trench Dec 1979

Interpolating Functions Associated With Second Order Differential, William F. Trench

William F. Trench

No abstract provided.

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Centers Of Polymer Research; Polymer Science And Technology In The Ddr, Otto Vogl Dec 1979

Centers Of Polymer Research; Polymer Science And Technology In The Ddr, Otto Vogl

Otto Vogl

No abstract provided.

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Increased Access To Medical Care: The Impact On Health, Paula Diehr Oct 1979

Increased Access To Medical Care: The Impact On Health, Paula Diehr

Paula Diehr

Many federally financed programs have been launched to improve the access of the poor to medical care, under the assumption that this will improve their health. The effectiveness of these programs, however, has generally been measured by increased utilization rather than by improved health. The few studies which have considered health status have shown small or negative effects. Here, data are presented from a project which provided fully prepaid care to near poor families through existing sources in the community. A group of 748 enrollees was found to report worse health on four of five health indicators after one year …

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Equatorial Electricfields During Magnetically Disturbed Conditions, 1. The Effect Of The Interplanetary Magneticfield, Bela G. Fejer, C. A. Gonzales, D. T. Farley, M. C. Kelley, R. F. Woodman Sep 1979

Equatorial Electricfields During Magnetically Disturbed Conditions, 1. The Effect Of The Interplanetary Magneticfield, Bela G. Fejer, C. A. Gonzales, D. T. Farley, M. C. Kelley, R. F. Woodman

Bela G. Fejer

Radar measurements of E and F region drift velocities have been used to look for correlations between changes in equatorial electric fields and the interplanetary magnetic field (IMF). The east-west component of the IMF appears to be unimportant, but the north-south component has some effect; rapid reversals from south to north are sometimes correlated with reversals of the equatorial east-west electric field during both daytime and nighttime. This is not always true, however, the IMF may reverse without any apparent effect at the equator. Furthermore, large equatorial field perturbations are sometimes observed when the IMF Bz is large and southward …

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Vesicular-Arbuscular Mycorrhiza Influence Growth But Not Mineral Concentrations In Seedlings Of Eight Sweetgum Families, Richard C. Schultz, Paul P. Kormanik, W. Craig Bryan, G. H. Brister Jun 1979

Vesicular-Arbuscular Mycorrhiza Influence Growth But Not Mineral Concentrations In Seedlings Of Eight Sweetgum Families, Richard C. Schultz, Paul P. Kormanik, W. Craig Bryan, G. H. Brister

Richard C. Schultz

Seedlings of eight half-sib sweetgum (Liquidambar styraciflua L.) families were grown for 6 months in a fumigated soil mixture, with or without inoculum from a mixture of Glomus mosseae and Glomus etunicatus fungi, at levels of 140, 280, 560, and 1120 kg/ha of 10-10-10 fertilizer. All seedlings received three additions of 187 kg/ha of N during the growing season. Inoculated seedlings had significantly greater biomass, height, and stem diameters at each fertilizer level than nonmycorrhizal control seedlings. Significant differences in growth occurred between families in mycorrhizal plants. However, fertilizer did not significantly affect growth or nutrient uptake of the seedlings. …

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Hidrometalurjide Yeni, Fathi Habashi Jan 1979

Hidrometalurjide Yeni, Fathi Habashi

Fathi Habashi

Turkish translation of F. Habashi, “Recent Advances in Hydrometallurgy,” Proceedings International Mineral Processing Congress, Warsaw, 1979, edited by J. Laskowski, published by Elsevier, pp. 902–935

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Excited States And Photochemistry Of Saturated Molecules. Vii. Potential Energy Surfaces In Excited Singlet States Of Methane, Mark S. Gordon, James W. Caldwell Jan 1979

Excited States And Photochemistry Of Saturated Molecules. Vii. Potential Energy Surfaces In Excited Singlet States Of Methane, Mark S. Gordon, James W. Caldwell

Mark S. Gordon

Potential energy surfaces are investigated for a number of low‐lying excited singlet states of methane, using a split valence plus Rydberg basis set and singly excited CI. Of the six minima found, the lowest two are valence states. The lowest minimum corresponds to the products 1 1 B 1 CH2+1 1Σ g + H2, in agreement with the observed threshold photochemistry, and is accessible by five separate routes from the lowest vertical state. The second valence minimum is a square planar structure. Of the four Rydberg minima detected, one is a local minimum on the otherwise dissociative B 1surface and …

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Temperature Dependent Spatial Order In Superfluid And Normal 4he, Robert Hallock, H. N. Robkoff, D. A. Ewen Jan 1979

Temperature Dependent Spatial Order In Superfluid And Normal 4he, Robert Hallock, H. N. Robkoff, D. A. Ewen

Robert Hallock

Measurements of the structure factor S(k) for 4He at constant density above and below Tλ are reported. The results show a clear loss of spatial order on cooling through Tλ. Application of the theory of Cummings, Hyland, and Rowlands to the data allows a measurement of the condensate fraction for He II.

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Behavior Of Persistent Currents Under Conditions Of Strong Decay, Robert Hallock, D. T. Ekholm Jan 1979

Behavior Of Persistent Currents Under Conditions Of Strong Decay, Robert Hallock, D. T. Ekholm

Robert Hallock

We report observations of the decay of persistent currents of thin superfluid 4He films for which the superfluid velocity deviates strongly from the previously observed logt behavior. We present data which document the evolution of this behavior as a function of film thickness. The Iordanskii-Langer-Fisher theory does not accurately describe our observation

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Gas Phase Laser Induced Fluorescence Spectroscopy Of Cfcl, Stephen E. Bialkowski, David S. King, John C. Stephenson Jan 1979

Gas Phase Laser Induced Fluorescence Spectroscopy Of Cfcl, Stephen E. Bialkowski, David S. King, John C. Stephenson

Stephen E. Bialkowski

The CFCl radical has been produced in the gas phase by both IR multiphotonphotolysis of C2F3Cl and He metastable reaction with C2F3Cl. Single vibronic level fluorescence and excitation spectra taken of this species have yielded sufficient information to determine certain vibronic constants. The excited state was found to have an origin of T0=25 283±5 cm−1 with vibrational frequencies: ω2′=394±3 cm−1 and ω3′=739±5 cm−1. In the ground state, the vibrational frequencies were found to be: ω3″=118±10 cm−1, ω2″=448±6 cm …

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Equatorialelectric Fields During Magnetically Disturbed Conditions, 2. Implications Of Simultaneousauroral And Equatorial Measurements, C. A. Gonzales, M. C. Kelley, Bela G. Fejer, J. F. Vickrey, R. F. Woodman Jan 1979

Equatorialelectric Fields During Magnetically Disturbed Conditions, 2. Implications Of Simultaneousauroral And Equatorial Measurements, C. A. Gonzales, M. C. Kelley, Bela G. Fejer, J. F. Vickrey, R. F. Woodman

Bela G. Fejer

Simultaneous auroral and equatorial electric field data are used along with magnetic field data to study anomalous electric field patterns during disturbed times. During some substorms, accompanied by ring current activity, the worldwide equatorial zonal electric field component reverses from the normal pattern. This is interpreted as a partial closure of high latitude field aligned currents in the dayside, low latitude ionosphere. These currents flow westward across the dayside. In several cases the zonal equatorial electric field component was nearly identical in form to the zonal auroral component, indicating the close electrical coupling between these regions. Less certain, but equally …

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Laminations, Or How To Build A Quantum-Logic-Valued Model Of Set Theory, Lawrence Stout Dec 1978

Laminations, Or How To Build A Quantum-Logic-Valued Model Of Set Theory, Lawrence Stout

Lawrence N. Stout

An explicit construction of the colimit of a filtered diagram in the category of topoi and logical morphisms is given and then used to construct a family of topoi with a fixed Boolean algebra of truth values but with varying amounts of cocompleteness. This same construction, when applied to the diagram of complete Boolean algebras in a quantum logic Q gives a partial topos, a noncategory which is a close to being a model of set theory with algebra of truth values Q as a noncategory can be.

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Imaging Of Paramagnetic Centres In Diamond, M.J. R. Hoch, Anthony Roy Day Dec 1978

Imaging Of Paramagnetic Centres In Diamond, M.J. R. Hoch, Anthony Roy Day

Anthony Roy Day

An imaging method for determining the spatial distribution of paramagnetic nitrogen centres in diamond is described. Results are presented for a sample consisting of two small type IB diamonds.

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Band Matrices With Toeplitz Inverses, William F. Trench, T N. E. Greville Dec 1978

Band Matrices With Toeplitz Inverses, William F. Trench, T N. E. Greville

William F. Trench

No abstract provided.

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Emp Analysis Of An Fm Communications Radio With A Long Wire Antenna, George H. Baker Iii, Werner J. Stark May 1978

Emp Analysis Of An Fm Communications Radio With A Long Wire Antenna, George H. Baker Iii, Werner J. Stark

George H Baker

A Norton equivalent circuit is developed for a long-wire antenna used with a VHF man-pack FM radio exposed to an incident electromagnetic pulse (EMP). The required short-circuit current and antenna impedance are computed by use of a transmission-line model for the antenna, and the computations are compared with measurements of the short-circuit current and antenna impedance. The comparison shows that the transmission-line model for the antenna is adequate for performing a vulnerability analysis of the radio. A network model is developed for a portion of the radio and is used as the load in the Norton equivalent circuit. Load currents …

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Second-Row Molecular Orbital Calculations. 5. A Minimal Basis Indo For Sodium-Chlorine, Mark S. Gordon, Mark D. Bjorke, Fred J. Marsh, Michael S. Korth Apr 1978

Second-Row Molecular Orbital Calculations. 5. A Minimal Basis Indo For Sodium-Chlorine, Mark S. Gordon, Mark D. Bjorke, Fred J. Marsh, Michael S. Korth

Mark S. Gordon

An INDO method is developed for molecules containing Na-CJ. Using only valences and p orbitals, the parametrization is carried out in the spirit of the approach originally taken by Pople and co-workers. The reliability of the method is tested by calculating geometries, dipole moments, and internal rotation barriers for approximately 100 molecules. The improvement in predictive ability relative to previous parametrizations is considerable. Predicted geometries are nearly as good as those for ST03G. Dipole moments of molecules containing Si and Clare in excellent agreement with experiment, while for P and S the agreement is only fair.

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Admissible Solutions Of Finite State Sequence Compound Decision Problems, Stephen B. Vardeman Jan 1978

Admissible Solutions Of Finite State Sequence Compound Decision Problems, Stephen B. Vardeman

Stephen B. Vardeman

A general method of constructing procedures which are both admissible and asymptotically optimal in finite state sequence compound decision problems is suggested and applied to the situation of a two state classification component. When used in an empirical Bayes setting, procedures so constructed are seen to be both admissible and asymptotically optimal.

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Excited States And Photochemistry Of Saturated Molecules. Ix. Vertical Excited States Of Silane, Mark S. Gordon Jan 1978

Excited States And Photochemistry Of Saturated Molecules. Ix. Vertical Excited States Of Silane, Mark S. Gordon

Mark S. Gordon

The vertical excited states of silane are investigated using ten different basis sets to systematically compare the effects of (a) Rydberg functions, (b) diffuse d functions, (c) valence d functions, and (d) a split valence shell. Wavefunctions are generated using all singly excited configurations, excluding inner shells. The low‐lying singlet states are dominated by excitations into the diffuse orbitals, while low‐lying triplets have significant valence character. Valence d functions have a minor effect on excitation energies if an adequate valence s p basis set is used. The main effect of Rydbergd functions is to introduce additional Rydberg states below the …

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Recent Climatic Fluctuations Of The Canadian High Arctic And Their Significance For Glaciology, Raymond S. Bradley, John England Jan 1978

Recent Climatic Fluctuations Of The Canadian High Arctic And Their Significance For Glaciology, Raymond S. Bradley, John England

Raymond S Bradley

Various measures of the character of ablation season conditions in the Canadian High Arctic (north of 74°N) are discussed based on an analysis of daily climatic data from Alert, Eureka, Isachsen, Resolute, and Thule. Melting degree day totals appear to be the most useful index of "summer warmth." An abrupt change in the summer climate of the region occurred around 1963164. Various indices indicate a marked decrease in summer temperature after 1963. During the same period, annual precipitation in the north and northwest has increased. Glacier mass balance is strongly controlled by summer climate; in particular, annual melting degree day …

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Former Ice Shelves In The Canadian High Arctic, John England, Raymond S. Bradley, G. H. Miller Jan 1978

Former Ice Shelves In The Canadian High Arctic, John England, Raymond S. Bradley, G. H. Miller

Raymond S Bradley

ABSTRACT. Moraines deposited by the outermost ice advance across Judge Daly Promontory, northeastern Ellesmere Island, reflect thin, topographically controlled ice lobes extending to sea-level. The termini of two ice lobes were investigated and both produced ice shelves where they flowed into isostatically depressed embayments along western Kennedy Channel. Morphological evidence for these ice shelves occurs at the entrance to these valleys where steeply descending lateral moraines become abruptly horizontal for 2 km. In addition, both the horizontal moraines and associated pro-glacial terraces are fossiliferous downvalley from the apparent grounding line. Based on the differences in elevation between the horizontal moraines …

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Direct Observation Of Pulsed Third Sound Mass Displacement Waves In Unsaturated Superfluid 4he Films, Robert Hallock, J. S. Brooks, F. M. Ellis Jan 1978

Direct Observation Of Pulsed Third Sound Mass Displacement Waves In Unsaturated Superfluid 4he Films, Robert Hallock, J. S. Brooks, F. M. Ellis

Robert Hallock

We report direct observation of pulsed third-sound film thickness oscillations in unsaturated superfluid 4He films using a capacitance technique. Simultaneous measurements of accompanying temperature oscillations allow the first study of the relative amplitudes of these oscillations and the results are in reasonable agreement with the theory of Bergman although some discrepancies are noted.

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Collisionless Formation And Rovibronic Relaxation Of Ch And Oh From The Ir Multiphoton Photolysisof Ch3Oh, Stephen E. Bialkowski, William A. Guillory Jan 1978

Collisionless Formation And Rovibronic Relaxation Of Ch And Oh From The Ir Multiphoton Photolysisof Ch3Oh, Stephen E. Bialkowski, William A. Guillory

Stephen E. Bialkowski

A CO2 TEA laser has been used to initiate the collisionless multiphotondissociation of CH3OH between 1000 and 10 mtorr. The appearance of OH(X2Πi) 50±20 nsec after the laser pulse, independent of initial CH3OH pressure (50–200 mtorr), suggests the primary dissociative channel CH3OH+n hν→CH3 +OH(X2Πi); although CH3 could not be correspondingly confirmed. The appearance of CH(X2Πr) 70±20 nsec after the OH(X) appearance, independent of initial CH3OH pressure (70–400 mtorr), suggests secondary collisionless dissociation. Initial rovibronic distributions of OH(X) …

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Radar Observations Of Two Dimensional Turbulencein The Equatorial Electrojet, 3. Nighttime Observations Of Type I Waves, D. T. Farley, Bela G. Fejer, B. B. Balsley Jan 1978

Radar Observations Of Two Dimensional Turbulencein The Equatorial Electrojet, 3. Nighttime Observations Of Type I Waves, D. T. Farley, Bela G. Fejer, B. B. Balsley

Bela G. Fejer

The large vertically directed 50-MHz radar at Jicamarca has sufficient sensitivity to study nighttime echoes from the equatorial electrojet in detail with good resolution. Here we concentrate on type 1 (‘two-stream’) echoes. We find that (1) these echoes sometimes dominate the spectrum (which is never the case in daytime for a vertically directed radar), (2) they are observed over a much wider range of altitudes than they are during daytime, (3) they show an asymmetry which reverses from day to night (downgoing waves are more common at night), (4) the magnitude of the mean Doppler shift appears to increase somewhat …

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Influence Of Endomycorrhizae On Growth Of Sweetgum Seedlings From Eight Mother Trees, Richard C. Schultz, Paul P. Kormanik, William C. Bryan Dec 1977

Influence Of Endomycorrhizae On Growth Of Sweetgum Seedlings From Eight Mother Trees, Richard C. Schultz, Paul P. Kormanik, William C. Bryan

Richard C. Schultz

Sweetgum seedlings from eight mother trees were grown in fumigated soil with or without the endomycorrhizal fungus Glomus mosseae at four levels of soil fertility for one growing season in nursery microplots. Nonmycorrhizal seedlings of all families died or failed to exceed 5 cm in height regardless of soil fertility. Endomycorrhizal seedlings suffered little mortality, averaged about 36 cm in height, and fertility level did not significantly influence their biomass. These results demonstrate that to increase the percentage of plantable seedlings in nurseries sweetgum seedlings must be endomycorrhizal. The data further suggests that adequate endomycorrhizal inoculum in nursery beds can …

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