Stability and Hermitian-Einstein metrics for vector bundles on framed manifolds

We adapt the notions of stability of holomorphic vector bundles in the sense of Mumford-Takemoto and Hermitian-Einstein metrics in holomorphic vector bundles for canonically polarized framed manifolds, i.e. compact complex manifolds X together with a smooth divisor D such that K_X \otimes [D] is ample. It turns out that the degree of a torsion-free coherent sheaf on X with respect to the polarization K_X \otimes [D] coincides with the degree with respect to the complete K\"ahler-Einstein metric g_{X \setminus D} on X \setminus D. For stable holomorphic vector bundles, we prove the existence of a Hermitian-Einstein metric with respect to g_{X \setminus D} and also the uniqueness in an adapted sense.Comment: 21 pages, International Journal of Mathematics (to appear

Abrupt Emergence of Pressure-Induced Superconductivity of 34 K in SrFe2As2: A Resistivity Study under Pressure

We report resistivity measurement under pressure in single crystals of SrFe_2As_2, which is one of the parent materials of Fe-based superconductors. The structural and antiferromagnetic (AFM) transition of T_0 = 198 K at ambient pressure is suppressed under pressure, and the ordered phase disappears above P_c ~ 3.6-3.7 GPa. Superconductivity with a sharp transition appears accompanied by the suppression of the AFM state. T_c exhibits a maximum of 34.1 K, which is realized close to the phase boundary at P_c. This T_c is the highest among those of the stoichiometric Fe-based superconductors.Comment: 4 pages, 4 figures, to be published in J. Phys. Soc. Jpn. 78 No.1 (2009

Electronic states of disordered grain boundaries in graphene prepared by chemical vapor deposition

Perturbations of the two dimensional carbon lattice of graphene, such as grain boundaries, have significant influence on the charge transport and mechanical properties of this material. Scanning tunneling microscopy measurements presented here show that localized states near the Dirac point dominate the local density of states of grain boundaries in graphene grown by chemical vapor deposition. Such low energy states are not reproduced by theoretical models which treat the grain boundaries as periodic dislocation-cores composed of pentagonal-heptagonal carbon rings. Using ab initio calculations, we have extended this model to include disorder, by introducing vacancies into a grain boundary consisting of periodic dislocation-cores. Within the framework of this model we were able to reproduce the measured density of states features. We present evidence that grain boundaries in graphene grown on copper incorporate a significant amount of disorder in the form of two-coordinated carbon atoms. © 2013 Elsevier Ltd. All rights reserved

Children with hyperdiploid but not triple trisomy (+4,+10,+17) acute lymphoblastic leukemia have an increased incidence of extramedullary relapse on current therapies: A single institution experience

To evaluate the outcome of children with high hyperdiploid acute lymphoblastic leukemia (hHDALL) treated at the author's institution. One hundred thirty-five consecutive children with B-precursor ALL were diagnosed between 1991 and 2002: 38 (28.1%) hHDALL and 97 (71.9%) non-hHDALL. In the hHDALL group, 11/38 (28.9%) relapsed at a median interval of 2.8 years (range: 0.8–5.0 years) with 9/11 relapses occurring at the end or after the completion of therapy. Three (27.3%) relapses were isolated hematopoietic (BM), while eight (72.7%) were either isolated extramedullary (EM) relapses ( n = 6; Testis: 4; CNS: 2) or combined hematopoietic and extramedullary relapses ( n = 2; BM + CNS: 1; BM + Testis: 1). For the non-hHDALL group, 29/97 (29.9%) relapsed. Unlike the hHDALL group, the non-hHDALL group experienced hematopoietic relapses (62%; n = 18) more frequently than isolated extramedullary (27.5%; n = 8: Testis: 1; CNS: 7) or combined hematopoietic and extramedullary relapses (10.3%; CNS + BM: 3), with 24/29 (82.8%) of the relapses occurring on therapy. Relapses in hHDALL frequently involved EM sites ( P = 0.053). Presence of triple trisomy of +4,+10,+17 at diagnosis had a protective effect against relapse ( P < 0.05). Five-year EFS for the hHDALL and non-hHDALL patients was similar, 70.5 ± 7.5% and 66.4 ± 4.9%, respectively. Five-year OS for the hHDALL patients was significantly higher than for the non-hHDALL patients, 92 ± 4.5% vs. 74.1 ± 4.5%, P = 0.038. Biologically significant differences exist between relapse patterns of hHDALL and non-hHDALL cases related to relapse sites and time periods when relapses occur. hDALL relapses continue to be chemo-sensitive. Am. J. Hematol., 2008. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57520/1/21011_ftp.pd

Effect of Uniaxial Stress for Pressure-Induced Superconductor SrFe_2As_2

We report that the pressure-temperature phase diagram of single-crystalline SrFe$_2$As$_2$ is easily affected by the hydrostaticity of a pressure-transmitting medium. For all of the three mediums we used, superconductivity with zero resistance appears, accompanied by the suppression of an antiferromagnetic (orthorhombic) phase, but the critical pressure $P_c$ was found to depend on the type of medium. $P_c$ was estimated to be 4.4 GPa under almost hydrostatic condition, but it decreased to $3.4-3.7$ GPa with the use of the medium already solidified at room temperature. The uniaxial stress along the c-axis is suggested to aid in the suppression of the antiferromagnetic (orthorhombic) phase. The pressure effect of BaFe$_2$As$_2$ is also reported.Comment: 4 pages, 5 figures, to be published in J. Phys. Soc. Jpn. No.8 (2009

The Role of TLR4 in the Paclitaxel Effects on Neuronal Growth In Vitro

Paclitaxel (Pac) is an antitumor agent that is widely used for treatment of solid cancers. While being effective as a chemotherapeutic agent, Pac in high doses is neurotoxic, specifically targeting sensory innervations. In view of these toxic effects associated with conventional chemotherapy, decreasing the dose of Pac has been recently suggested as an alternative approach, which might limit neurotoxicity and immunosuppression. However, it remains unclear if low doses of Pac retain its neurotoxic properties or might exhibit unusual effects on neuronal cells. The goal of this study was to analyze the concentration-dependent effect of Pac on isolated and cultured DRG neuronal cells from wild-type and TLR4 knockout mice. Three different morphological parameters were analyzed: the number of neurons which developed neurites, the number of neurites per cell and the total length of neurites per cell. Our data demonstrate that low concentrations of Pac (0.1 nM and 0.5 nM) do not influence the neuronal growth in cultures in both wild type and TLR4 knockout mice. Higher concentrations of Pac (1-100 nM) had a significant effect on DRG neurons from wild type mice, affecting the number of neurons which developed neurites, number of neurites per cell, and the length of neurites. In DRG from TLR4 knockout mice high concentrations of Pac showed a similar effect on the number of neurons which developed neurites and the length of neurites. At the same time, the number of neurites per cell, indicating the process of growth cone initiation, was not affected by high concentrations of Pac. Thus, our data showed that Pac in high concentrations has a significant damaging effect on axonal growth and that this effect is partially mediated through TLR4 pathways. Low doses of Pac are devoid of neuronal toxicity and thus can be safely used in a chemomodulation mode. © 2013 Ustinova et al

Inhibition of G Protein-Activated Inwardly Rectifying K+ Channels by Different Classes of Antidepressants

Various antidepressants are commonly used for the treatment of depression and several other neuropsychiatric disorders. In addition to their primary effects on serotonergic or noradrenergic neurotransmitter systems, antidepressants have been shown to interact with several receptors and ion channels. However, the molecular mechanisms that underlie the effects of antidepressants have not yet been sufficiently clarified. G protein-activated inwardly rectifying K+ (GIRK, Kir3) channels play an important role in regulating neuronal excitability and heart rate, and GIRK channel modulation has been suggested to have therapeutic potential for several neuropsychiatric disorders and cardiac arrhythmias. In the present study, we investigated the effects of various classes of antidepressants on GIRK channels using the Xenopus oocyte expression assay. In oocytes injected with mRNA for GIRK1/GIRK2 or GIRK1/GIRK4 subunits, extracellular application of sertraline, duloxetine, and amoxapine effectively reduced GIRK currents, whereas nefazodone, venlafaxine, mianserin, and mirtazapine weakly inhibited GIRK currents even at toxic levels. The inhibitory effects were concentration-dependent, with various degrees of potency and effectiveness. Furthermore, the effects of sertraline were voltage-independent and time-independent during each voltage pulse, whereas the effects of duloxetine were voltage-dependent with weaker inhibition with negative membrane potentials and time-dependent with a gradual decrease in each voltage pulse. However, Kir2.1 channels were insensitive to all of the drugs. Moreover, the GIRK currents induced by ethanol were inhibited by sertraline but not by intracellularly applied sertraline. The present results suggest that GIRK channel inhibition may reveal a novel characteristic of the commonly used antidepressants, particularly sertraline, and contributes to some of the therapeutic effects and adverse effects

Axion Searches

The strong CP problem and its resolution through the existence of an axion are briefly reviewed. The constraints on the axion from accelerator searches, from the evolution of red giants and from supernova SN1987a combine to require $m_a < 3 \cdot 10^{-3}$ eV, where $m_a$ is the axion mass. On the other hand, the constraint that axions do not overclose the universe implies m_a \gtwid 10^{-6} eV. If $m_a \sim 10^{-5}$ eV, axions contribute significantly to the cosmological energy density in the form of cold dark matter. Dark matter axions can be detected by resonant conversion to microwave photons in a cavity permeated by a static magnetic field and tuned to the axion mass. Experiments using this effect are described, as well as several other types of axion searches.Comment: 12 pages, 2 figures, based on talks at the TAUP99 Conference (Sept. 6-10, 1999, Paris, France) and at Adrianfest (Sept. 24-25, 1999, Rochester, NY

Spinor Bose-Einstein condensates

An overview on the physics of spinor and dipolar Bose-Einstein condensates (BECs) is given. Mean-field ground states, Bogoliubov spectra, and many-body ground and excited states of spinor BECs are discussed. Properties of spin-polarized dipolar BECs and those of spinor-dipolar BECs are reviewed. Some of the unique features of the vortices in spinor BECs such as fractional vortices and non-Abelian vortices are delineated. The symmetry of the order parameter is classified using group theory, and various topological excitations are investigated based on homotopy theory. Some of the more recent developments in a spinor BEC are discussed.Comment: To appear in Physics Reports. The PDF file with high resolution figures is available from the following website: http://cat.phys.s.u-tokyo.ac.jp/publication/review_of_spinorBEC.pd