1,201 research outputs found
Voltage from mechanical stress in type-II superconductors: Depinning of the magnetic flux by moving dislocations
Mechanical stress causes motion of defects in solids. We show that in a
type-II superconductor a moving dislocation generates a pattern of current that
exerts the depinning force on the surrounding vortex lattice. Concentration of
dislocations and the mechanical stress needed to produce critical depinning
currents are shown to be within practical range. When external magnetic field
and transport current are present this effect generates voltage across the
superconductor. Thus a superconductor can serve as an electrical sensor of the
mechanical stress.Comment: 3 pages, 1 figure
Minimal qubit tomography
We present, and analyze thoroughly, a highly symmetric and efficient scheme
for the determination of a single-qubit state, such as the polarization
properties of photons emitted by a single-photon source. In our scheme there
are only four measured probabilities, just enough for the determination of the
three parameters that specify the qubit state, whereas the standard procedure
would measure six probabilities.Comment: 14 pages, 10 figures; final versio
Variation in fiberoptic bead-based oligonucleotide microarrays: dispersion characteristics among hybridization and biological replicate samples
BACKGROUND: Gene expression microarray technology continues to evolve and its use has expanded into all areas of biology. However, the high dimensionality of the data makes analysis a difficult challenge. Evaluating measurements and estimating the significance of the observed differences among samples remain important issues that must be addressed for each technology platform. In this work we use a consecutive sampling method to characterize the dispersion patterns of data generated from Illumina fiberoptic bead-based oligonucleotide arrays. RESULTS: To describe general properties of the dispersion we used a linear function SD = a + bY(mean), approximating the standard deviation across arrays (Y(mean )is the mean expression of a given consecutive sample). First we examined three levels of variability: 1) same cell culture, same reverse transcription, duplicate hybridizations; 2) same cell culture, reverse transcription replicates; 3) parallel cultures. Each higher level is expected to introduce a new source of variability. We observed minor differences in the constant term: the mean values are 3.5, 3.1 and 3.5, respectively. However, the mean coefficient b increased from 0.045 to 0.147 and 0.133. We compared the coefficients derived from the consecutive sampling to those obtained from the standard deviation of individual gene expressions and found them in good agreement. In the second experiment samples we detected 11 genes with systematically different expressions between the experiment samples treated with glucose oxidase and controls and corroborated the selection using the Mann-Whitney and other tests. We also compared the consecutive sampling and coincidence method to t-test: the average percentage of consistency was above 80 for the former and below 50 for the latter. CONCLUSION: Our results indicate that the consecutive sampling method and standard deviation function provide a convenient description of the overall dispersion of Illumina arrays. We observed that the constant term of the standard deviation function is at average approximately the same for duplicate hybridization as for the assays with additional sources of variability. Furthermore, among the genes affected by glucose oxidase treatment we identified 6 genes in oxidative stress pathways and 5 genes involved in DNA repair. Finally, we noted that the consecutive sampling and coincidence test provide, under given conditions, more consistent results than the t-test. REVIEWERS: This article was reviewed by Alexander Karpikov (nominated by MarkGerstein), Jordan King and Eugene V. Koonin
Influence of maltodextrin dextrose equivalent value on rheological and dispersion properties of sunflower oil in water emulsions
Effect of dextrose equivalent (DE) of maltodextrin present in continuous phase on flow along with dispersion properties of sunflower oil in water emulsions has been investigated. Both, rheological and disperse characteristics of the emulsions were greatly influenced by continuous phase viscosity and thus by the DE value of maltodextrin.. The smaller DE value the greater high shear viscosity and the smaller the droplet size. Irrespective of the amount and DE value of maltodextrin used was, all the emulsions showed a pseudoplastic behaviour
Strong Correlations in Electron Doped Phthalocyanine Conductors Near Half Filling
We propose that electron doped nontransition metal-phthalocyanines (MPc) like
ZnPc and MgPc, similar to those very recently reported, should constitute novel
strongly correlated metals. Due to orbital degeneracy, Jahn-Teller coupling and
Hund's rule exchange, and with a large on-site Coulomb repulsion, these
molecular conductors should display, particularly near half filling at two
electrons/molecule, very unconventional properties, including Mott insulators,
strongly correlated superconductivity, and other intriguing phases.Comment: 4 pages, 1 figure, submited to PR
Quantum dynamics and statistics of two coupled down-conversion processes
In the framework of Heisenberg-Langevin theory the dynamical and statistical
effects arising from the linear interaction of two nondegenerate
down-conversion processes are investigated. Using the strong-pumping
approximation the analytical solution of equations of motion is calculated. The
phenomena reminiscent of Zeno and anti-Zeno effects are examined. The
possibility of phase-controlled and mismatch-controlled switching is
illustrated.Comment: 17 pages, 7 figure
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