1,090 research outputs found

    On Self-Validation

    Get PDF

    Change of Electronic Structure Induced by Magnetic Transitions in CeBi

    Full text link
    The temperature dependence of the electronic structure of CeBi arising from two types of antiferromagnetic transitions based on optical conductivity (Ļƒ(Ļ‰)\sigma(\omega)) was observed. The Ļƒ(Ļ‰)\sigma(\omega) spectrum continuously and discontinuously changes at 25 and 11 K, respectively. Between these temperatures, two peaks in the spectrum rapidly shift to the opposite energy sides as the temperature changes. Through a comparison with the band calculation as well as with the theoretical Ļƒ(Ļ‰)\sigma(\omega) spectrum, this peak shift was explained by the energy shift of the Bi 6p6p band due to the mixing effect between the Ce 4fĪ“84f \Gamma_8 and Bi 6p6p states. The single-layer antiferromagnetic (+āˆ’+-) transition from the paramagnetic state was concluded to be of the second order. The marked changes in the Ļƒ(Ļ‰)\sigma(\omega) spectrum at 11 K, however, indicated the change in the electronic structure was due to a first-order-like magnetic transition from a single-layer to a double-layer (++āˆ’āˆ’++--) antiferromagnetic phase.Comment: 4 pages, to be published in J. Phys. Soc. Jpn. 73 Aug. (2004

    Rhodium-catalyzed dehydrogenative borylation of cyclic alkenes

    Get PDF
    A rhodium-catalyzed dehydrogenative borylation of cyclic alkenes is described. This reaction provides direct access to cyclic 1-alkenylboronic acid pinacol esters, useful intermediates in organic synthesis. Suzukiā€“Miyaura cross-coupling applications are also presented.National Institute of General Medical Sciences (U.S.) (GM-63755

    High-resolution mass models of dwarf galaxies from LITTLE THINGS

    Get PDF
    We present high-resolution rotation curves and mass models of 26 dwarf galaxies from LITTLE THINGS. LITTLE THINGS is a high-resolution Very Large Array HI survey for nearby dwarf galaxies in the local volume within 11 Mpc. The rotation curves of the sample galaxies derived in a homogeneous and consistent manner are combined with Spitzer archival 3.6 micron and ancillary optical U, B, and V images to construct mass models of the galaxies. We decompose the rotation curves in terms of the dynamical contributions by baryons and dark matter halos, and compare the latter with those of dwarf galaxies from THINGS as well as Lambda CDM SPH simulations in which the effect of baryonic feedback processes is included. Being generally consistent with THINGS and simulated dwarf galaxies, most of the LITTLE THINGS sample galaxies show a linear increase of the rotation curve in their inner regions, which gives shallower logarithmic inner slopes alpha of their dark matter density profiles. The mean value of the slopes of the 26 LITTLE THINGS dwarf galaxies is alpha =-0.32 +/- 0.24 which is in accordance with the previous results found for low surface brightness galaxies (alpha = -0.2 +/- 0.2) as well as the seven THINGS dwarf galaxies (alpha =-0.29 +/- 0.07). However, this significantly deviates from the cusp-like dark matter distribution predicted by dark-matter-only Lambda CDM simulations. Instead our results are more in line with the shallower slopes found in the Lambda CDM SPH simulations of dwarf galaxies in which the effect of baryonic feedback processes is included. In addition, we discuss the central dark matter distribution of DDO 210 whose stellar mass is relatively low in our sample to examine the scenario of inefficient supernova feedback in low mass dwarf galaxies predicted from recent Lambda SPH simulations of dwarf galaxies where central cusps still remain.Peer reviewe

    Band Calculation for Ce-compounds on the basis of Dynamical Mean Field Theory

    Full text link
    The band calculation scheme for ff electron compounds is developed on the basis of the dynamical mean field theory (DMFT) and the LMTO method. The auxiliary impurity problem is solved by a method named as NCAf2f^{2}v', which includes the correct exchange process of the f1ā†’f2f^{1} \to f^{2} virtual excitation as the vertex correction to the non-crossing approximation (NCA) for the f1ā†’f0f^{1} \to f^{0} fluctuation. This method leads to the correct magnitude of the Kondo temperature, TKT_{\rm K}, and makes it possible to carry out quantitative DMFT calculation including the crystalline field (CF) and the spin-orbit (SO) splitting of the self-energy. The magnetic excitation spectra are also calculated to estimate TKT_{\rm K}. It is applied to Ce metal and CeSb at T=300 K as the first step. In Ce metal, the hybridization intensity (HI) just below the Fermi energy is reduced in the DMFT band. The photo-emission spectra (PES) have a conspicuous SO side peak, similar to that of experiments. TKT_{\rm K} is estimated to be about 70 K in Ī³\gamma-Ce, while to be about 1700 K in Ī±\alpha-Ce. In CeSb, the double-peak-like structure of PES is reproduced. In addition, TKT_{\rm K} which is not so low is obtained because HI is enhanced just at the Fermi energy in the DMFT band.Comment: 30pages, 18 figure

    Intracochlear schwannoma presenting as diffuse cochlear enhancement: diagnostic challenges of a rare cause of deafness

    Get PDF
    Intracochlear schwannoma is a rare, treatable, cause of unilateral hearing loss. Due to the small size, position, and variable clinical and imaging features, diagnosis presents a significant challenge and is often delayed. We present a case of a patient with an intracochlear schwannoma presenting as a diffuse enhancement of the cochlea, mimicking an infectious or inflammatory process. The absence of focal nodularity in this lesion on multiple high-resolution MRI examinations led to a delay of over 3 years from the patientā€™s initial presentation to surgical diagnosis. Clinical history and examination, imaging features, pathologic findings, and surgical management options are described
    • ā€¦
    corecore