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Articles 751 - 780 of 784

Full-Text Articles in Physical Sciences and Mathematics

Nonenzymatic Glucosylation And Glucose-Dependent Cross-Linking Of Protein, Albert S. Eble, Suzanne R. Thorpe, John W. Baynes Aug 1983

Nonenzymatic Glucosylation And Glucose-Dependent Cross-Linking Of Protein, Albert S. Eble, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

A model system using RNase A has been established for studying the nonenzymatic glucosylation and glucose-dependent cross-linking of protein (Maillard reaction) under physiological conditions in vitro. The rate of glucosylation of RNase was first order in glucose. Glucosylation was accompanied by a comparable decrease in primary amino groups in the protein and lysine recoverable by amino acid analysis. Analysis of glucosylation reaction mixtures by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of mercaptoethanol revealed the time-dependent formation of RNase dimer and trimer. The polymerization reaction was mixed order with respect to glucose concentration, but was approximately first order with …

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Conductance In Restricted-Dimensionality Accumulation Layers, A. B. Fowler, A. Hartstein, Richard A. Webb Jan 1982

Conductance In Restricted-Dimensionality Accumulation Layers, A. B. Fowler, A. Hartstein, Richard A. Webb

Faculty Publications

Conductance has been studied in metal-oxide-silicon field-effect transistor accumulation-layer samples in which it is possible to constrict the channel to small dimensions both perpendicular to the surface and perpendicular to the channel. A temperature-dependent conductance σ=σ0exp[-(T0/T)n] is observed, where n=1/2 for small channel widths and n=1/3 for larger channel widths. It is believed that this behavior arises from a transition from one-dimensional to two-dimensional variable-range hopping in the sample.

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Some Comments On The Erdos-Renyl Law And A Theorem Of Shepp, James Lynch Jan 1982

Some Comments On The Erdos-Renyl Law And A Theorem Of Shepp, James Lynch

Faculty Publications

We show that the finiteness of the moment generating function is necessary for the finiteness of the lim sup of the moving averages considered by Shepp (1964). This also implies that the same must be true for the Erdos-Renyi law of large numbers.

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Metrizability And The Frechet-Urysohn Property In Topological Groups, Peter J. Nyikos Dec 1981

Metrizability And The Frechet-Urysohn Property In Topological Groups, Peter J. Nyikos

Faculty Publications

A question of Arhangel'skii, whether weakly first countable topological groups are metrizable, is answered in two ways: if the Hausdorff axiom is assumed, the answer is yes, but in general a weakly first countable topological group need not be pseudometrizable. The former result is obtained as a corollary of a more general sufficient condition for a sequential group to be Fr&chet-Urysohn. A general necessary and sufficient condition for a sequential group to be Frechet-Urysohn is given, and a number of questions are raised. Examples are given to show in what respect the theorems of the paper are the "best possible".

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Macroscopic Quantum Tunneling In 1-Μm Nb Josephson Junctions, Richard F. Voss, Richard A. Webb Jul 1981

Macroscopic Quantum Tunneling In 1-Μm Nb Josephson Junctions, Richard F. Voss, Richard A. Webb

Faculty Publications

The probability distributions for switching out of the superconducting state of low-cur-rent-density 1-μm Nb Josephson junctions with capacitance ≈ 0.1 pF have been measured as a function of temperature T down to 3 mK. Below 100 mK the distribution widths become independent of T. The results are in excellent agreement with predictions for the quantum tunneling of the (macroscopic) junction phase that include the reduction of tunneling rates due to dissipation.

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An Octic Reciprocity Law Of Scholz Type, Duncan A. Buell, Kenneth S. Williams Dec 1979

An Octic Reciprocity Law Of Scholz Type, Duncan A. Buell, Kenneth S. Williams

Faculty Publications

No abstract provided.

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Nonenzymatic Glucosylation Of Rat Albumin: Studies In Vitro And In Vivo, James F. Day, Robert W. Thornburg, Suzanne R. Thorpe, John W. Baynes Oct 1979

Nonenzymatic Glucosylation Of Rat Albumin: Studies In Vitro And In Vivo, James F. Day, Robert W. Thornburg, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Incubation of rat serum with D-glucose in vitro resulted in nonenzymatic glucosylation of serum proteins. Analysis of freshly isolated rat albumin by ion exchange chromatography indicated that the glucosylated albumin accounts for 6.7.+-. 0.9% of total albumin in normal rat serum. Glucosylation of rat albumin in vitro was 1st order with respect to glucose and albumin concentrations and occurs primarily (> 90%) at intrachain lysine residues. Kinetic analysis and inhibition of glucosylation by aspirin suggest that 1 reactive lysine residue is the primary site of glucosylation. Less than 5% of the radioactivity from glucosyl-albumin was released as glucose or mannose …

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Spin-Glass-Like Behavior In Very Dilute Pdfe At Very Low Temperatures, Richard A. Webb, G. W. Crabtree, J. J. Vuillemin Sep 1979

Spin-Glass-Like Behavior In Very Dilute Pdfe At Very Low Temperatures, Richard A. Webb, G. W. Crabtree, J. J. Vuillemin

Faculty Publications

Measurements of the electrical resistivity of palladium, residual resistivity ratio ∼22 500, containing 1.7 ppm of Fe have been made from 5.5 K to 1.8 mK. 15 Hz ac susceptibility measurements from 1 K to 1.8 mK together with the resistivity data suggest that a transition into a spin-glass state occurs near 7 mK.

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Enhanced Nonenzymatic Glucosylation Of Human Serum Albumin In Diabetes Mellitus, C. Earl Guthrow, Mary Ann Morris, James F. Day, Suzanne R. Thorpe, John W. Baynes Sep 1979

Enhanced Nonenzymatic Glucosylation Of Human Serum Albumin In Diabetes Mellitus, C. Earl Guthrow, Mary Ann Morris, James F. Day, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Use of an ion exchange chromatographic method and a colorimetric method with thiobarbituric acid showed that levels of nonenzymatically glucosylated serum albumin were increased in patients with poorly controlled diabetes mellitus compared to controls. The two methods correlated well (r = 0.99) and clearly discriminated between normal and poorly controlled diabetic populations. The levels of glycosylated hemoglobin were also measured in both populations. Several patients apparently in good control based on glycosylated hemoglobin measurements were found to have increased levels of glycosylated albumin. Because albumin has a shorter circulating half-life than does the human erythrocyte, the plasma concentration of glucosylated …

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Nonenzymatically Glucosylated Albumin: In Vitro Preparation And Isolation From Normal Human Serum, James F. Day, Suzanne R. Thorpe, John W. Baynes Feb 1979

Nonenzymatically Glucosylated Albumin: In Vitro Preparation And Isolation From Normal Human Serum, James F. Day, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Incubation of human serum with D-[6-3H]glucose resulted in the gradual accumulation of radioactivity in acid-precipitable material. Upon chromatography on Sephadex G-200, radioactivity was found associated with each of the major molecular weight classes of serum protein. Purified human serum albumin was also glucosylated in vitro upon exposure to D-[6-3H]glucose in phosphate-buffered saline. The glucosylated and unmodified albumins were separated by ion exchange chromatography. The physiological significance of these observations in vitro was confirmed by the isolation and quantitation of glucosylated albumin from normal human serum. Glucosylated albumin represents approximately 6 to 15% of total serum albumin in normal adults. The …

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[3H]‑Raffinose, A Novel Radioactive Label For Determining Organ Sites Of Catabolism Of Proteins In The Circulation, Jonathon Van Zile, Lee A. Henderson, John W. Baynes, Suzanne R. Thorpe Sep 1978

[3H]‑Raffinose, A Novel Radioactive Label For Determining Organ Sites Of Catabolism Of Proteins In The Circulation, Jonathon Van Zile, Lee A. Henderson, John W. Baynes, Suzanne R. Thorpe

Faculty Publications

The primary tissue sites of catabolism of plasma proteins with long circulating half-lives are unknown. It has been difficult to identify these sites because plasma proteins are delivered to tissues at relatively slow rates but are rapidly degraded intracellularly within lysosomes. Therefore, a tracer attached to protein is lost from the site of uptake before an amount sufficient for quantitation can accumulate. We hypothesized that sucrose (Glupal-2 /3Fruf) would be a useful label to circumvent this difficulty because of the stability of sucrose in lysosomes; and thus, sucrose should remain in tissue long after the protein to which it was …

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Bayes Estimation Of Reliability For Mixtures Of Life Distributions, William J. Padgett, Chris P. Tsokos Jun 1978

Bayes Estimation Of Reliability For Mixtures Of Life Distributions, William J. Padgett, Chris P. Tsokos

Faculty Publications

No abstract provided.

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Maximal Residue Difference Sets Modulo P, Duncan A. Buell, Kenneth S. Williams May 1978

Maximal Residue Difference Sets Modulo P, Duncan A. Buell, Kenneth S. Williams

Faculty Publications

Let p ≡ 1 (mod 4) be a prime. A residue difference set modulo p is a set S = {ai} of integers ai such that (ai/p) = +1 and ((ai - aj)/p) = +1 for all i and j with i ≠ j, where (n/p) is the Legendre symbol modulo p. Let mp be the cardinality of a maximal such set S. The authors estimate the size of mp.

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Tip-Angle-Dependent Magnetic Relaxation In Superfluid 3he, Richard A. Webb Mar 1978

Tip-Angle-Dependent Magnetic Relaxation In Superfluid 3he, Richard A. Webb

Faculty Publications

Using a pulsed superconducting-quantum-interference-device (SQUID) NMR technique, relaxation of the longitudinal magnetization in superfluid 3He has been measured in magnetic fields of 31, 102, 180, and 306 Oe in the pressure range 16-26 bar. It is observed that in both superfluid phases there is a temperature-dependent, well-defined spin-tipping angle, θc, for which the relaxation of the magnetization changes from an exponential to a nonexponential behavior.

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Ferromagneticlike Resonance Behavior In Superfluid 3he-B, Richard A. Webb Oct 1977

Ferromagneticlike Resonance Behavior In Superfluid 3he-B, Richard A. Webb

Faculty Publications

Nonlinear cw NMR behavior, similar to that observed on ferromagnets at high rf powers, has been observed in superfluid 3He-B using a superconducting quantum interference device (SQUID) magnetometer in fields of 31, 102, 180, and 308 Oe and at a pressure of 21 bar. It is observed that beyond some threshold value of the transverse H1 field the z component of magnetization anomalously decreases and is followed by a rapid increase back to the normal resonance curve as the frequency of the H1 field is swept through resonance.

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Fragments Of 1st-Order Logic, I: Universal Horn Logic, George F. Mcnulty Jun 1977

Fragments Of 1st-Order Logic, I: Universal Horn Logic, George F. Mcnulty

Faculty Publications

No abstract provided.

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Measurement Of The Difference Between The Dynamic Nmr And Static Susceptibilites Of Superfluid 3he-B Using An Rf-Biased Superconducting Quantum-Interference Device, Richard A. Webb May 1977

Measurement Of The Difference Between The Dynamic Nmr And Static Susceptibilites Of Superfluid 3he-B Using An Rf-Biased Superconducting Quantum-Interference Device, Richard A. Webb

Faculty Publications

The temperature-dependent susceptiblity of superfluid 3He-B has been measured both statically and via a pulse technique in a field of 309 G using an rf-biased superconducting quantum-interference device (SQUID). In the pressure range 26.5 to 18 bar, the dynamic NMR susceptiblity agrees qualitatively with the theoretical weak-coupling predictions for the Balian-Werthamer state. However, the static susceptiblity, measured using the same rf-biased SQUID and detection system, is significantly smaller thatn the dynamic susceptibility.

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A Random Differential-Equation Approach To Probability Distribution Of Bod And Do In Streams, William J. Padgett, G Schultz, Chris P. Tsokos Mar 1977

A Random Differential-Equation Approach To Probability Distribution Of Bod And Do In Streams, William J. Padgett, G Schultz, Chris P. Tsokos

Faculty Publications

No abstract provided.

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Effect Of Glycosylation On The In Vivo Circulating Half-Life Of Ribonuclease, John W. Baynes, Finn Wold Oct 1976

Effect Of Glycosylation On The In Vivo Circulating Half-Life Of Ribonuclease, John W. Baynes, Finn Wold

Faculty Publications

The circulating half-lives of the four isozymes of bovine pancreatic ribonuclease (RNases A, B, C, and D) have been determined in normal and in nephrectomized rats. The isozymes differ only in their glycosyl content. While A contains no sugars, B has a simple oligosaccharide (GlcNAc, Man,+), and C and D each have a complex oligosaccharide (GlcNAc, Man,., Gal, Fuc NeuAc%, and GlcNAc, Mans Gal, Fuc NeuAc,, respectively) attached to Asn-34 of the polypeptide chain. All four isozymes were cleared rapidly in normal rats (t,,, = 2 to 3 min), as expected on the basis of the established role of the …

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Application Of Theorems Of Schur And Albert, Thomas L. Markham Sep 1976

Application Of Theorems Of Schur And Albert, Thomas L. Markham

Faculty Publications

No abstract provided.

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Undecidable Properties Of Finite Sets Of Equations, George F. Mcnulty Sep 1976

Undecidable Properties Of Finite Sets Of Equations, George F. Mcnulty

Faculty Publications

No abstract provided.

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Relaxation Of The Wall-Pinned Magnetization Ringing Mode In Superfluid 3he-B, Richard A. Webb, R. E. Sager, J. C. Wheatley Oct 1975

Relaxation Of The Wall-Pinned Magnetization Ringing Mode In Superfluid 3he-B, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

Observations of the wall-pinned mode in 3He-B allow new magnetic relaxation phenomena to be studied. Excepting the quantitative value of the zero-time ringing frequency, comparison of experiment with theory is satisfactory, including a linear dependence of the square of the ringing period on time and a square-root singularity near Tc in the relaxation parameter.

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Nonlinear Parallel Ringing Of Magnetization In Superfluid 3he, Richard A. Webb, R. E. Sager, J. C. Wheatley Oct 1975

Nonlinear Parallel Ringing Of Magnetization In Superfluid 3he, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

Experiments based on an analogy to the ac Josephson effect have shown in both 3He-A and 3He-B that a pairing theory of the superfluidity of 3He is essentially correct. Additional observations of parallel ringing are not in agreement with the simple "pendulum models" used to describe nonlinear dynamic magnetic effects.

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Relationship Between The Linear Ringing Frequencies In 3he-A And 3he-B Near The Polycritical Point, Richard A. Webb, R. E. Sager, J. C. Wheatley Sep 1975

Relationship Between The Linear Ringing Frequencies In 3he-A And 3he-B Near The Polycritical Point, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

New measurements of parallel ringing in a quasi-ideal geometry for 3He-B near the temperature and pressure of the polycritical point suggest fB2/fA2∼5/2, where fB and fA are the linear parallel-ringing frequencies at a given temperature near Tc. This result approaches the prediction of theory using the Anderson-Brinkman-Morel and Balian-Werthamer states to describe 3He-A and 3He-B, respectively, and hence the results of Osheroff at melting pressure, but disagrees with earlier observations at pressures near the polycritical point.

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Application Of Separation Theorem For Hermitian Matrices, Thomas L. Markham Jan 1975

Application Of Separation Theorem For Hermitian Matrices, Thomas L. Markham

Faculty Publications

No abstract provided.

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Experiments On Dynamic Parallel Magnetism In Superfluid 3he, Richard A. Webb, R. L. Kleinberg, J. C. Wheatley Jul 1974

Experiments On Dynamic Parallel Magnetism In Superfluid 3he, Richard A. Webb, R. L. Kleinberg, J. C. Wheatley

Faculty Publications

Observations are reported of the ringing of parallel magnetization in superfluid 3He when an incremental magnetic field parallel to a steady field is suddenly turned off.

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The Role Of A Dolichol-Oligosaccharide As An Intermediate In Glycoprotein Biosynthesis, An-Fei Hsu, John W. Baynes, Edward C. Heath Jun 1974

The Role Of A Dolichol-Oligosaccharide As An Intermediate In Glycoprotein Biosynthesis, An-Fei Hsu, John W. Baynes, Edward C. Heath

Faculty Publications

Incubation of mouse myeloma microsomes with GDP-[(14)C]mannose results in the biosynthesis of [(14)C]mannose phosphoryl dolichol [Baynes, J. W., Hsu, A.-F. & Heath, E. C. (1973) J. Biol. Chem. 248, 5693-5704] and a [(14)C]mannose- and N-acetylglucosamine (GlcNAc)-containing oligosaccharide derivative of dolichol. Thus, [(14)C]mannose phosphoryl dolichol and [(14)C]mannose-labeled oligosaccharide pyrophosphoryl dolichol were isolated from incubation mixtures by solubilization in 2% (w/v) Triton X-100 and the lipids were separated from small molecules by gel filtration fractionation. After removal of radioactive protein from the preparation, the two lipid derivatives were separated quantitatively by fractionation on a concanavalin A-Sepharose column; [(14)C]mannose phosphoryl dolichol was not …

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Graphs With 1-Factors, David Sumner Jan 1974

Graphs With 1-Factors, David Sumner

Faculty Publications

In this paper it is shown that if G is a connected graph of order 2n (n > 1) not containing a 1-factor, then for each k, 1

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The Role Of Mannosyl-Phosphoryl-Dihydropolyisoprenol In The Synthesis Of Mammalian Glycoproteins, John W. Baynes, An-Fei Hsu, Edward C. Heath Aug 1973

The Role Of Mannosyl-Phosphoryl-Dihydropolyisoprenol In The Synthesis Of Mammalian Glycoproteins, John W. Baynes, An-Fei Hsu, Edward C. Heath

Faculty Publications

A mouse myeloma tumor was used as a model system to study the biochemical steps involved in the incorporation of mannose into glycoproteins. This tumor, MOPC-46B, synthesizes a K-type immunoglobulin light chain (K-46) which is a glycoprotein with a single oligosaccharide side chain containing mannose as one of its constituent sugars. MOPC-46B microsomal preparations contain enzymes which transfer mannose from the sugar nucleotide, GDPmannose, to endogenous lipid and protein acceptors. Formation of the mannolipid proceeds by the reversible transfer of mannose from GDP-mannose to an endogenous phospholipid. The mannolipid was purified and characterized by chemical methods and mass spectrometry as …

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Nonlinear Stochastic Integral-Equation Of Hammerstein Type, William J. Padgett May 1973

Nonlinear Stochastic Integral-Equation Of Hammerstein Type, William J. Padgett

Faculty Publications

No abstract provided.

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