154 research outputs found
Femtosecond core level photoemision spectroscopy on 1T-TaS2 using 60 eV laser source
Time-resolved photoelectron spectroscopy (trPES) can directly detect
transient electronic structure, thus bringing out its promising potential to
clarify nonequilibrium processes arising in condensed matters. Here we report
the result of core-level (CL) trPES on 1T-TaS2, realized by developing a
high-intensity 60 eV laser obtained by high-order harmonic (HH) generation.
Ta4f CL-trPES offers the transient amplitude of the charge-density-wave (CDW),
via the site-selective and real-time observation of Ta electrons. The present
result indicates an ultrafast photoinduced melting and recovery of CDW
amplitude, followed by a peculiar long-life oscillation (i.e. collective
amplitudon excitation) accompanying the transfer of 0.01 electrons among
adjacent Ta atoms. CL-trPES offers a broad range of opportunities for
investigating the ultrafast atom-specific electron dynamics in photo-related
phenomena of interest
Magnetic-susceptibility and specific-heat studies on the inhomogeneity of superconductivity in the underdoped La_2-x_Sr_x_CuO_4_
The possible inhomogeneity of superconductivity has been investigated by
means of bulk-sensitive probes, using La_2-x_Sr_x_CuO_4_ (LSCO) single crystals
from the underdoped to optimally doped regime. Measurements of the magnetic
susceptibility, chi, on field cooling and specific heat have revealed that both
the absolute value of chi at 2 K, regarded as corresponding to the
superconducting (SC) volume fraction in a sample, and the Sommerfeld constant,
reflecting the density of states of quasiparticles at the Fermi level, exhibit
significant dependence on x, namely, on the hole concentration. This is the
first experimental work strongly suggesting that a phase separation into SC and
normal-state regions takes place in the underodped regime of LSCO as well as in
the overdoped regime.Comment: 7 pages, 4 figures, the version 2 has been accepted for publication
in J. Phys. Soc. Jp
Localization and Superconductivity in Doped Semiconductors
Motivated by the discovery of superconductivity in boron-doped (B-doped)
diamond, we investigate the localization and superconductivity in heavily doped
semiconductors. The competition between Anderson localization and s-wave
superconductivity is investigated from the microscopic point of view. The
effect of microscopic inhomogeneity and the thermal fluctuation in
superconductivity are taken into account using the self-consistent 1-loop-order
theory with respect to superconducting fluctuation. The crossover from
superconductivity in the host band to that in the impurity band is described on
the basis of the disordered three-dimensional attractive Hubbard model for
binary alloys. We show that superconductor-insulator transition (SIT)
accompanies the crossover. We point out an enhancement of Cooper pairing in the
crossover regime. Further localization of the electron wave function gives rise
to incoherent Cooper pairs and the pseudogap above T_c. A global phase diagram
is drawn for host band superconductivity, impurity band superconductivity,
Anderson localization, Fermi liquid state, and pseudogap state. A theoretical
interpretation is proposed for superconductivity in the doped diamond, SiC, and
Si.Comment: Final version for publication. To appear in J. Phys. Soc. Jpn. (2009)
No.
Interferon-α/β and Anti-Fibroblast Growth Factor Receptor 1 Monoclonal Antibody Suppress Hepatic Cancer Cells In Vitro and In Vivo
Hepatocellular carcinoma (HCC) is the most commonly occurring primary liver cancer and ranks as the fifth most frequently occurring cancer, overall, and the third leading cause of cancer deaths, worldwide. At present, effective therapeutic options available for HCC are limited; consequently, the prognosis for these patients is poor. Our aim in the present study was to identify a novel target for antibody therapy against HCC..Our results suggest that the combined use of an anti-FGFR1 antibody and interferon-α/β is a promising approach to the treatment of HCC
Search for Periodic Time Variations of the Solar B Neutrino Flux Between 1996 and 2018 in Super-Kamiokande
We report a search for time variations of the solar B neutrino flux using
5,804 live days of Super-Kamiokande data collected between May 31, 1996, and
May 30, 2018. Super-Kamiokande measured the precise time of each solar neutrino
interaction over 22 calendar years to search for solar neutrino flux
modulations with unprecedented precision. Periodic modulations are searched for
in a data set comprised of five-day interval solar neutrino flux measurements
with a maximum likelihood method. We also applied the Lomb-Scargle method to
this data set to compare it with previous reports. The only significant
modulation found is due to the elliptic orbit of the Earth around the Sun. The
observed modulation is consistent with astronomical data: we measured an
eccentricity of (1.530.35)\,\%, and a perihelion shift is
(1.513.5)\,days.Comment: 8 pages, 5 figures, 2 tables, and data file:
"sksolartimevariation5804d.txt
Search for astrophysical electron antineutrinos in Super-Kamiokande with 0.01wt% gadolinium-loaded water
We report the first search result for the flux of astrophysical electron
antineutrinos for energies O(10) MeV in the gadolinium-loaded Super-Kamiokande
(SK) detector. In June 2020, gadolinium was introduced to the ultra-pure water
of the SK detector in order to detect neutrons more efficiently. In this new
experimental phase, SK-Gd, we can search for electron antineutrinos via inverse
beta decay with efficient background rejection and higher signal efficiency
thanks to the high efficiency of the neutron tagging technique. In this paper,
we report the result for the initial stage of SK-Gd with a exposure at 0.01% Gd mass concentration. No significant excess
over the expected background in the observed events is found for the neutrino
energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90%
confidence level. The limits and sensitivities are already comparable with the
previous SK result with pure-water () owing
to the enhanced neutron tagging
Immune plexins and semaphorins: old proteins, new immune functions
Plexins and semaphorins are a large family of proteins that are involved in cell movement and response. The importance of plexins and semaphorins has been emphasized by their discovery in many organ systems including the nervous (Nkyimbeng-Takwi and Chapoval, 2011; McCormick and Leipzig, 2012; Yaron and Sprinzak, 2012), epithelial (Miao et al., 1999; Fujii et al., 2002), and immune systems (Takamatsu and Kumanogoh, 2012) as well as diverse cell processes including angiogenesis (Serini et al., 2009; Sakurai et al., 2012), embryogenesis (Perala et al., 2012), and cancer (Potiron et al., 2009; Micucci et al., 2010). Plexins and semaphorins are transmembrane proteins that share a conserved extracellular semaphorin domain (Hota and Buck, 2012). The plexins and semaphorins are divided into four and eight subfamilies respectively based on their structural homology. Semaphorins are relatively small proteins containing the extracellular semaphorin domain and short intra-cellular tails. Plexins contain the semaphorin domain and long intracellular tails (Hota and Buck, 2012). The majority of plexin and semaphorin research has focused on the nervous system, particularly the developing nervous system, where these proteins are found to mediate many common neuronal cell processes including cell movement, cytoskeletal rearrangement, and signal transduction (Choi et al., 2008; Takamatsu et al., 2010). Their roles in the immune system are the focus of this review
- …