Faraday rotation spectra of bismuth-substituted ferrite garnet films with in-plane magnetization

Single crystalline films of bismuth-substituted ferrite garnets have been synthesized by the liquid phase epitaxy method where GGG substrates are dipped into the flux. The growth parameters are controlled to obtain films with in-plane magnetization and virtually no domain activity, which makes them excellently suited for magnetooptic imaging. The Faraday rotation spectra were measured across the visible range of wavelengths. To interprete the spectra we present a simple model based on the existence of two optical transitions of diamagnetic character, one tetrahedral and one octahedral. We find excellent agreement between the model and our experimental results for photon energies between 1.77 and 2.53 eV, corresponding to wavelengths between 700 and 490 nm. It is shown that the Faraday rotation changes significantly with the amount of substituted gallium and bismuth. Furthermore, the experimental results suggest that the magnetooptic response changes linearly with the bismuth substitution.Comment: 15 pages, 6 figures, published in Phys. Rev.

Critical currents in Josephson junctions, with unconventional pairing symmetry: dx2−y2+isd_{x^2-y^2}+is versus dx2−y2+idxyd_{x^2-y^2}+id_{xy}

Phenomenological Ginzburg-Landau theory is used to calculate the possible spontaneous vortex states that may exist at corner junctions of $d_{x^2-y^2}+ix$-wave, (where $x=s$ or $x=d_{xy}$) and s-wave superconductors. We study the magnetic flux and the critical current modulation with the junction orientation angle $\theta$, the magnitude of the order parameter, and the magnetic field $H$. It is seen that the critical current $I_c$ versus the magnetic flux $\Phi$ relation is symmetric / asymmetric for $x=d_{xy}/s$ when the orientation is exactly such that the lobes of the dominant $d_{x^2-y^2}$-wave order parameter points towards the two junctions, which are at right angles for the corner junction. The conclusion is that a measurement of the $I_c(\Phi)$ relation may distinguish which symmetry ($d_{x^2-y^2}+is$ or $d_{x^2-y^2}+id_{xy}$) the order parameter has.Comment: 11 pages with 11 figures, Changed conten

Anomalous Flux Flow Resistivity in Two Gap Superconductor MgB_2

The flux flow resistivity associated with purely viscous motion of vortices in high-quality MgB_2 was measured by microwave surface impedance. Flux flow resistivity exhibits unusual field dependence with strong enhancement at low field, which is markedly different to conventional s-wave superconductors. A crossover field which separates two distinct flux flow regimes having different flux flow resistivity slopes was clearly observed in H//ab-plane. The unusual H-dependence indicates that two very differently sized superconducting gaps in MgB_2 manifest in the vortex dynamics and almost equally contribute to energy dissipation. The carrier scattering rate in two different bands is also discussed with the present results, compared to heat capacity and thermal conductivity results.Comment: 4 pages, 3figure

Differential metabolism of deoxyribonucleosides by leukaemic T cells of immature and mature phenotype

Experimental evidence has indicated that T lymphoblasts are more sensitive to deoxynucleoside toxicity than are B lymphoblasts. These data have led to the use of purine enzyme inhibitors as selective chemotherapeutic drugs in the treatment of T cell malignancies ranging from T cell acute lymphoblastic leukaemia to cutaneous T cell lymphomas. We have compared the toxicities of 2′-deoxyadenosine, 2′-deoxyguanosine, and thymidine for T cell lines derived from patients with T cell acute lymphoblastic leukaemia with those for mature T cell lines derived from patients with cutaneous T cell leukaemia/lymphoma. We have found that both deoxynucleosides are far less toxic to the mature T cell lies than to T lymphoblasts and that the mature cells accumulate much lower amounts of dATP and dGTP when exposed to deoxyadenosine and deoxyguanosine, respectively. Similar studies performed on peripheral blood cells from patients with T cell leukaemias of mature phenotype and on peripheral blood T cells demonstrate similar low amounts of deoxynucleotide accumulation. Measurements of the activities of several purine metabolizing enzymes that participate in deoxynucleoside phosphorylation or degradation do not reveal differences which would explain the toxicity of deoxynucleosides for immature, as compared to mature, T cells. We conclude that deoxynucleoside metabolism in leukaemic T cells varies with their degree of differentiation. These observations may be relevant to the design of chemotherapeutic regimes for T cell malignancies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72479/1/j.1365-2141.1985.tb04067.x.pd

Manifestation of Resonance-Related Chaos in Coupled Josephson Junctions

Chaotic features of systems of coupled Josephson junctions are studied. Manifestation of chaos in the temporal dependence of the electric charge, related to a parametric resonance, is demonstrated through the calculation of the maximal Lyapunov exponent, phase-charge and charge-charge Lissajous diagrams and correlation functions. The number of junctions in the stack strongly influences the fine structure in the current voltage characteristics and a strong proximity effect results from the nonperiodic boundary conditions. The observed resonance-related chaos exhibits intermittency over a range of conditions and parameters. General features of the system are analyzed by means of a linearized equation and the criteria for a breakpoint region with no chaos are obtained. Such criteria could clarify recent experimental observations of variations in the power output from intrinsic Josephson junctions in high temperature superconductors.Comment: 13 pages, 16 figure

Pharmacologic intervention for prevention of fractures in osteopenic and osteoporotic postmenopausal women: Systemic review and meta-analysis

Objectives Emerging evidence has indicated a role for pharmacologic agents in the primary prevention of osteoporotic fracture, but have not yet been systematically reviewed for meta-analysis. We conducted a meta-analysis to evaluate the efficacy of pharmacologic interventions in reducing fracture risk and increasing bone mineral density (BMD) in postmenopausal women with osteopenia or osteoporosis but without prevalent fragility fracture. Method The Medline, EMBASE, and CENTRAL databases were searched from inception to September 30, 2019. Only randomized placebo-controlled trials evaluating postmenopausal women with −1.0 > bone mineral density (BMD) T-score > −2.5 (low bone mass) and those with BMD T-score ≤ −2.5 (osteoporosis) but without baseline fractures, who were receiving anti-osteoporotic agents, providing quantitative outcomes data and evaluating risk of vertebral and/or non-vertebral fragility fracture at follow-up. The PRISMA guidelines were followed, applying a random-effects model. The primary endpoint was the effect of anti-osteoporotic regimens in reducing the incidence of vertebral fractures. Secondary endpoints were percentage changes in baseline BMD at the lumbar spine and total hip at 1 and 2 years follow up. Results Full-text review of 144 articles yielded, 20 for meta-analysis. Bisphosphonates reduced the risk of vertebral fracture (pooled OR = 0.50, 95%CIs = 0.36–0.71) and significantly increased lumbar spine BMD after 1 year, by 4.42% vs placebo (95%CIs = 3.70%–5.14%). At the hip, this value was 2.94% (95%CIs = 2.13%–3.75%). Overall results of limited studies for non-bisphosphonate drugs showed increased BMD and raloxifene significantly decreases the risk of subsequent clinical vertebral fractures. Conclusion The bisphosphonates are efficacious and most evident for the primary prevention of osteoporotic vertebral fractures, reducing their incidence and improving BMD in postmenopausal women with osteopenia or osteoporosis

Heavy Quarks and Heavy Quarkonia as Tests of Thermalization

We present here a brief summary of new results on heavy quarks and heavy quarkonia from the PHENIX experiment as presented at the "Quark Gluon Plasma Thermalization" Workshop in Vienna, Austria in August 2005, directly following the International Quark Matter Conference in Hungary.Comment: 8 pages, 5 figures, Quark Gluon Plasma Thermalization Workshop (Vienna August 2005) Proceeding

Single Electrons from Heavy Flavor Decays in p+p Collisions at sqrt(s) = 200 GeV

The invariant differential cross section for inclusive electron production in p+p collisions at sqrt(s) = 200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range $0.4 <= p_T <= 5.0 GeV/c at midrapidity (eta <= 0.35). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e. charm quarks or, at high p_T, bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined as sigma_(c c^bar) = 0.92 +/- 0.15 (stat.) +- 0.54 (sys.) mb.Comment: 329 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Nuclear Modification of Electron Spectra and Implications for Heavy Quark Energy Loss in Au+Au Collisions at sqrt(s_NN)=200 GeV

The PHENIX experiment has measured mid-rapidity transverse momentum spectra (0.4 < p_T < 5.0 GeV/c) of electrons as a function of centrality in Au+Au collisions at sqrt(s_NN)=200 GeV. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of pi^0 and eta mesons, were removed. The resulting non-photonic electron spectra are primarily due to the semi-leptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to non-photonic electrons in p+p collisions. A significant suppression of electrons at high p_T is observed in central Au+Au collisions, indicating substantial energy loss of heavy quarks.Comment: 330 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm