1,403 research outputs found

    On fundamental groups related to the Hirzebruch surface F_1

    Full text link
    Given a projective surface and a generic projection to the plane, the braid monodromy factorization (and thus, the braid monodromy type) of the complement of its branch curve is one of the most important topological invariants, stable on deformations. From this factorization, one can compute the fundamental group of the complement of the branch curve, either in C^2 or in CP^2. In this article, we show that these groups, for the Hirzebruch surface F_{1,(a,b)}, are almost-solvable. That is - they are an extension of a solvable group, which strengthen the conjecture on degeneratable surfaces.Comment: accepted for publication at "Sci. in China, ser. Math"; 22 pages, 11 figure

    Superconductivity in the Z2\mathbb{Z}_2 kagome metal KV3_3Sb5_5

    Full text link
    Here we report the observation of bulk superconductivity in single crystals of the two-dimensional kagome metal KV3_3Sb5_5. Magnetic susceptibility, resistivity, and heat capacity measurements reveal superconductivity below Tc=0.93T_c = 0.93K, and density functional theory (DFT) calculations further characterize the normal state as a Z2\mathbb{Z}_2 topological metal. Our results demonstrate that the recent observation of superconductivity within the related kagome metal CsV3_3Sb5_5 is likely a common feature across the AV3_3Sb5_5 (A: K, Rb, Cs) family of compounds and establish them as a rich arena for studying the interplay between bulk superconductivity, topological surface states, and likely electronic density wave order in an exfoliable kagome lattice

    Extrapyramidal side effects and suicidal ideation under fluoxetine treatment: a case report

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>We present the case of a 52-year-old woman with depression who developed extrapyramidal symptoms (mainly parkinsonism) and suicidal ideation while on fluoxetine.</p> <p>Methods</p> <p>The patient underwent neurological and neuroimaging examination.</p> <p>Results</p> <p>The patient's neurological and neuroimaging examinations were normal and there was no other cause of extrapyramidal symptoms. The patient showed remission of the aforementioned symptomatology when fluoxetine was discontinued.</p> <p>Conclusions</p> <p>This case shows that fluoxetine can be associated with extrapyramidal symptoms, and this may have an aggravating affect on clinical depression progress and the emergence of suicidal ideation.</p

    Epileptiform Activity in Alcohol Dependent Patients and Possibilities of Its Indirect Measurement

    Get PDF
    Background: Alcohol dependence during withdrawal and also in abstinent period in many cases is related to reduced inhibitory functions and kindling that may appear in the form of psychosensory symptoms similar to temporal lobe epilepsy frequently in conditions of normal EEG and without seizures. Because temporal lobe epileptic activity tend to spread between hemispheres, it is possible to suppose that measures reflecting interhemispheric information transfer such as electrodermal activity (EDA) might be related to the psychosensory symptoms. Methods and Findings: We have performed measurement of bilateral EDA, psychosensory symptoms (LSCL-33) and alcohol craving (ACQ) in 34 alcohol dependent patients and 32 healthy controls. The results in alcohol dependent patients show that during rest conditions the psychosensory symptoms (LSCL-33) are related to EDA transinformation (PTI) between left and right EDA records (Spearman r = 0.44, p,0.01). Conclusions: The result may present potentially useful clinical finding suggesting a possibility to indirectly assess epileptiform changes in alcohol dependent patients

    Fermi surface mapping and the nature of charge density wave order in the kagome superconductor CsV3_3Sb5_5

    Full text link
    The recently discovered family of AV3_3Sb5_5 (A: K, Rb Cs) kagome metals possess a unique combination of nontrivial band topology, superconducting ground states, and signatures of electron correlations manifest via competing charge density wave order. Little is understood regarding the nature of the charge density wave (CDW) instability inherent to these compounds and the potential correlation with the accompanying onset of a large anomalous Hall response. To understand the impact of the CDW order on the electronic structure in these systems, we present quantum oscillation measurements on single crystals of CsV3_3Sb5_5. Our data provides direct evidence that the CDW invokes a substantial reconstruction of the Fermi surface pockets associated with the vanadium orbitals and the kagome lattice framework. In conjunction with density functional theory modeling, we are able to identify split oscillation frequencies originating from reconstructed pockets built from vanadium orbitals and Dirac-like bands. Complementary diffraction measurements are further able to demonstrate that the CDW instability has a correlated phasing between neighboring V3_3Sb5_5 planes. These results provide critical insights into the underlying CDW instability in AV3_3Sb5_5 kagome metals and support minimal models of CDW order arising from within the vanadium-based kagome lattice.Comment: 12 pages, 9 figure

    Spectroscopic investigation of quantum confinement effects in ion implanted silicon-on-sapphire films

    Full text link
    Crystalline Silicon-on-Sapphire (SOS) films were implanted with boron (B+^+) and phosphorous (P+^+) ions. Different samples, prepared by varying the ion dose in the range 101410^{14} to 5 x 101510^{15} and ion energy in the range 150-350 keV, were investigated by the Raman spectroscopy, photoluminescence (PL) spectroscopy and glancing angle x-ray diffraction (GAXRD). The Raman results from dose dependent B+^+ implanted samples show red-shifted and asymmetrically broadened Raman line-shape for B+^+ dose greater than 101410^{14} ions cm2^{-2}. The asymmetry and red shift in the Raman line-shape is explained in terms of quantum confinement of phonons in silicon nanostructures formed as a result of ion implantation. PL spectra shows size dependent visible luminescence at \sim 1.9 eV at room temperature, which confirms the presence of silicon nanostructures. Raman studies on P+^+ implanted samples were also done as a function of ion energy. The Raman results show an amorphous top SOS surface for sample implanted with 150 keV P+^+ ions of dose 5 x 101510^{15} ions cm2^{-2}. The nanostructures are formed when the P+^+ energy is increased to 350 keV by keeping the ion dose fixed. The GAXRD results show consistency with the Raman results.Comment: 9 Pages, 6 Figures and 1 Table, \LaTex format To appear in SILICON(SPRINGER

    Increased methylation of glucocorticoid receptor gene (NR3C1) in adults with a history of childhood maltreatment: a link with the severity and type of trauma

    Get PDF
    Childhood maltreatment, through epigenetic modification of the glucocorticoid receptor gene (NR3C1), influences the hypothalamic–pituitary–adrenal axis (HPA axis). We investigated whether childhood maltreatment and its severity were associated with increased methylation of the exon 1F NR3C1 promoter, in 101 borderline personality disorder (BPD) and 99 major depressive disorder (MDD) subjects with, respectively, a high and low rate of childhood maltreatment, and 15 MDD subjects with comorbid post-traumatic stress disorder (PTSD). Childhood sexual abuse, its severity and the number of type of maltreatments positively correlated with NR3C1 methylation (P=6.16 × 10−8, 5.18 × 10−7 and 1.25 × 10−9, respectively). In BPD, repetition of abuses and sexual abuse with penetration correlated with a higher methylation percentage. Peripheral blood might therefore serve as a proxy for environmental effects on epigenetic processes. These findings suggest that early life events may permanently impact on the HPA axis though epigenetic modifications of the NR3C1. This is a mechanism by which childhood maltreatment may lead to adulthood psychopathology
    corecore