The spin anisotropy of the magnetic excitations in the normal and superconducting states of optimally doped YBa2Cu3O6.9 studied by polarized neutron spectroscopy

We use inelastic neutron scattering with spin polarization analysis to study the magnetic excitations in the normal and superconducting states of YBa2Cu3O6.9. Polarization analysis allows us to determine the spin polarization of the magnetic excitations and to separate them from phonon scattering. In the normal state, we find unambiguous evidence of magnetic excitations over the 10-60meV range of the experiment with little polarization dependence to the excitations. In the superconducting state, the magnetic response is enhanced near the "resonance energy" and above. At lower energies, 10<E<30meV, the local susceptibility becomes anisotropic, with the excitations polarized along the c-axis being suppressed. We find evidence for a new diffuse anisotropic response polarized perpendicular to the c-axis which may carry significant spectral weight.Comment: Various typos and errors (inc assignment of components) correcte

Measurement of Superluminal optical tunneling times in double-barrier photonic bandgaps

Tunneling of optical pulses at 1.5 micron wavelength through double-barrier periodic fiber Bragg gratings is experimentally investigated. Tunneling time measurements as a function of barrier distance show that, far from the resonances of the structure, the transit time is paradoxically short, implying Superluminal propagation, and almost independent of the distance between the barriers. These results are in agreement with theoretical predictions based on phase time analysis and also provide an experimental evidence, in the optical context, of the analogous phenomenon expected in Quantum Mechanics for non-resonant superluminal tunneling of particles across two successive potential barriers. [Attention is called, in particular, to our last Figure]. PACS nos.: 42.50.Wm, 03.65.Xp, 42.70.Qs, 03.50.De, 03.65.-w, 73.40.GkComment: LaTeX file (8 pages), plus 5 figure

Progress in Neutron Scattering Studies of Spin Excitations in High-Tc Cuprates

Neutron scattering experiments continue to improve our knowledge of spin fluctuations in layered cuprates, excitations that are symptomatic of the electronic correlations underlying high-temperature superconductivity. Time-of-flight spectrometers, together with new and varied single crystal samples, have provided a more complete characterization of the magnetic energy spectrum and its variation with carrier concentration. While the spin excitations appear anomalous in comparison with simple model systems, there is clear consistency among a variety of cuprate families. Focusing initially on hole-doped systems, we review the nature of the magnetic spectrum, and variations in magnetic spectral weight with doping. We consider connections with the phenomena of charge and spin stripe order, and the potential generality of such correlations as suggested by studies of magnetic-field and impurity induced order. We contrast the behavior of the hole-doped systems with the trends found in the electron-doped superconductors. Returning to hole-doped cuprates, studies of translation-symmetry-preserving magnetic order are discussed, along with efforts to explore new systems. We conclude with a discussion of future challenges.Comment: revised version, to be published in JPSJ, 20 pages, 21 figure

Quantitative genetic variation in carbonic anhydrase isozymes from tissues of the pig-tailed macaque, Macaca nemestrina

Two isozymes of carbonic anhydrase (CA I and CA II) were quantified by a radio-immunoassay in 10 different tissues of the pig-tailed macaque. There were clearly differences in relative amounts of the two isozymes, indicating a differential regulation of these two different gene products. An inherited deficiency variant reduced red cell CA I and CA II 5000-fold and 2.7-fold, respectively. In nine other tissues, CA I was reduced from approximately twofold to 110-fold, and CA II was essentially unchanged. The CA I in deficient red cells was immunochemically and electrophoretically identical to common electrophoretic variants of CA I in the pig-tailed macaque and was enzymatically active.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44174/1/10528_2004_Article_BF00485860.pd

Genetic variation in the carbonic anhydrase isozymes of macaque monkeys. II. Inheritance of red cell carbonic anhydrase levels in different carbonic anhydrase I genotypes of the pig-tailed macaque, Macaca nemestrina

The inheritance of red blood cell levels of carbonic anhydrase isozymes (CA I and CA II) has been studied in different carbonic anhydrase I genotypes of the pig-tailed macaque, Macaca nemestrina . Quantitation of CA I isozymes in a series of animals indicates that the total CA I concentration is the sum of the average effects of each CA I structural allele and that the average effects are independent of the various allelic combinations. The relative average effects were 0.32:0.95:1.0 for the CA I a , CA I b , and CA I c structural genes, respectively. It is also demonstrated that the level of CA II is related to the CA I genotypes. Multiple regression analysis demonstrated that each dose of CA I-deficiency gene present decreased the CA II concentration by approximately 30%, with this decrease in CA II level being solely related to the dose of CA I-deficiency gene and not to the level of CA I. The CA I-deficient animals produce CA I products that are similar to the common CA Ia, CA Ib, CA Ic electrophoretic types. Limited mating data indicate that the CA I components in CA I-deficient animals are inherited codominantly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44182/1/10528_2004_Article_BF00485544.pd

Carbonic anhydrase II is induced in HL-60 cells by 1,25-dihydroxyvitamin D3: A model for osteoclast gene regulation

Carbonic anhydrase II (CA II) generates the H+ required for osteoclast-mediated bone resorption in humans. We have developed the human promyelocytic cell line HL-60 as a model system with which to study the osteoclast-specific expression of the CA II gene. Treatment of the cell line with 1,25-dihydroxyvitamin D3 resulted in a dramatic de novo induction of CA II at both the protein and mRNA levels. CA II mRNA was also induced to a lesser extent by 12-O-tetradecanoyl phorbol 13-acetate. Treatment with dimethyl sulfoxide did not increase CA II mRNA. These findings indicate that the HL-60 cell line will be a useful model system to study the osteoclast-specific expression of the CA II gene.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27889/1/0000303.pd

Genetic variation and evolution in the red cell carbonic anhydrase isozymes of macaque monkeys

The electrophoretic phenotypes of the two isozymes of red cell carbonic anhydrase, CA I and CA II, are described in nine species of macaque monkeys from southeast Asia and Japan. Twelve phenotypes of CA I, apparently under the control of seven alleles, and five phenotypes of CA II, under the control of three alleles, were found in the different macaque populations studied. Extensive electrophoretic polymorphisms of CA I were found in three species (Macaca nemestrina, Macaca speciosa , and Macaca fuscata) , and polymorphisms at the CA II locus were found in Macaca irus, Macaca mulatta , and M. nemestrina . In addition to the electrophoretic polymorphisms at the CA I locus in M. nemestrina , an inherited deficiency of CA I was also discovered in which approximately 30% of the individuals in all populations of M. nemestrina tested showed the deficient phenotype. Although the recessive gene controlling this deficiency appears to be an allele of the CA I locus, it is postulated that the CA I deficiency could also be under the control of a closely linked gene. The comparative data on the extent of genetic variation observed in the two isozymes of red cell carbonic anhydrase in macaques appear to support the concept that CA I has evolved more rapidly than CA II in mammals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44171/1/10528_2004_Article_BF00485644.pd

Genetic control of quantitative variation in carbonic anhydrase isozymes of mammals. I. The concentration within single erythrocytes of the mouse

The levels of the carbonic anhydrase isozymes (CA and CA II) in single erythrocytes of DBA/2J mice were assayed by measuring the specific immunofluorescence of CA I and CA II with a microspectrofluorometric technique. Measurements of 100 randomly selected cells showed a range (in relative fluorescence units) of 21–52 (mean 31.3±7.5) for CA I and 30–80 (mean 45.6±10.7) for CA II. The CA II/CA I ratio of the means obtained by the single-cell fluorescence assay was similar to the ratios obtained for the two isozymes from hemolysates of DBA/2J mice using an immunodiffusion assay. The influence of cell age on the variation in carbonic anhydrase levels was determined by separating red cells into several fractions by a gravity sedimentation procedure. The younger cells showed higher levels of CA I and CA II than the older cells; however, the extensive overlap in the variability between the cells from the different fractions indicated that although cell age was contributing to the overall heterogeneity, its influence was not pronounced.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44126/1/10528_2004_Article_BF00483984.pd