35 research outputs found
Magnon Broadening Effects in Double Layered Manganite La_1.2 Sr_1.8 Mn_2 O_7
Magnon linewidth of La_1.2 Sr_1.8 Mn_2 O_7 near the Brillouin zone boundary
is investigated from both theoretical and experimental points of view. Abrupt
magnon broadening is ascribed to a strong magnon-phonon coupling. Magnon
broadening observed in cubic perovskite manganites is also discussed.Comment: 4 pages + 1 jpeg figur
Neutron Diffraction Study of Field Cooling Effects on Relaxor Ferroelectrics Pb[(Zn_{1/3} Nb_{2/3})_{0.92} Ti_{0.08}] O_{3}
High-temperature (T) and high-electric-field (E) effects on Pb[(Zn_{1/3}
Nb_{2/3})_{0.92} Ti_{0.08}]O_3 (PZN-8%PT) were studied comprehensively by
neutron diffraction in the ranges 300 <= T <= 550 K and 0 <= E <= 15 kV/cm. We
have focused on how phase transitions depend on preceding thermal and
electrical sequences. In the field cooling process (FC, E parallel [001] >= 0.5
kV/cm), a successive cubic (C) --> tetragonal (T) --> monoclinic (M_C)
transition was observed. In the zero field cooling process (ZFC), however, we
have found that the system does not transform to the rhombohedral (R) phase as
widely believed, but to a new, unidentified phase, which we call X. X gives a
Bragg peak profile similar to that expected for R, but the c-axis is always
slightly shorter than the a-axis. As for field effects on the X phase, we found
an irreversible X --> M_C transition via another monoclinic phase (M_A) as
expected from a previous report [Noheda et al. Phys. Rev. Lett. 86, 3891
(2001)]. At a higher electric field, we confirmed a c-axis jump associated with
the field-induced M_C --> T transition, which was observed by strain and x-ray
diffraction measurements.Comment: 8 pages, 9 figures, revise
Photopharmacological Manipulation of Mammalian CRY1 for Regulation of the Circadian Clock
CRY1 and CRY2 proteins are highly conserved components of the circadian clock that controls daily physiological rhythms. Disruption of CRY functions are related to many diseases, including circadian sleep phase disorder. Development of isoform-selective and spatiotemporally controllable tools will facilitate the understanding of shared and distinct functions of CRY1 and CRY2. Here, we developed CRY1-selective compounds that enable light-dependent manipulation of the circadian clock. From phenotypic chemical screening in human cells, we identified benzophenone derivatives that lengthened the circadian period. These compounds selectively interacted with the CRY1 photolyase homology region, resulting in activation of CRY1 but not CRY2. The benzophenone moiety rearranged a CRY1 region called the "lid loop"located outside of the compound-binding pocket and formed a unique interaction with Phe409 in the lid loop. Manipulation of this key interaction was achieved by rationally designed replacement of the benzophenone with a switchable azobenzene moiety whose cis-trans isomerization can be controlled by light. The metastable cis form exhibited sufficiently high half-life in aqueous solutions and structurally mimicked the benzophenone unit, enabling reversible period regulation over days by cellular irradiation with visible light. This study revealed an unprecedented role of the lid loop in CRY-compound interaction and paves the way for spatiotemporal regulation of CRY1 activity by photopharmacology for molecular understanding of CRY1-dependent functions in health and disease
Fundamental Parameters of the Milky Way Galaxy Based on VLBI astrometry
We present analyses to determine the fundamental parameters of the Galaxy
based on VLBI astrometry of 52 Galactic maser sources obtained with VERA, VLBA
and EVN. We model the Galaxy's structure with a set of parameters including the
Galaxy center distance R_0, the angular rotation velocity at the LSR Omega_0,
mean peculiar motion of the sources with respect to Galactic rotation (U_src,
V_src, W_src), rotation-curve shape index, and the V component of the Solar
peculiar motions V_sun. Based on a Markov chain Monte Carlo method, we find
that the Galaxy center distance is constrained at a 5% level to be R_0 = 8.05
+/- 0.45 kpc, where the error bar includes both statistical and systematic
errors. We also find that the two components of the source peculiar motion
U_src and W_src are fairly small compared to the Galactic rotation velocity,
being U_src = 1.0 +/- 1.5 km/s and W_src = -1.4 +/- 1.2 km/s. Also, the
rotation curve shape is found to be basically flat between Galacto-centric
radii of 4 and 13 kpc. On the other hand, we find a linear relation between
V_src and V_sun as V_src = V_sun -19 (+/- 2) km/s, suggesting that the value of
V_src is fully dependent on the adopted value of V_sun. Regarding the rotation
speed in the vicinity of the Sun, we also find a strong correlation between
Omega_0 and V_sun. We find that the angular velocity of the Sun, Omega_sun,
which is defined as Omega_sun = Omega_0 + V_sun/R_0, can be well constrained
with the best estimate of Omega_sun = 31.09 +/- 0.78 km/s/kpc. This corresponds
to Theta_0 = 238 +/- 14 km/s if one adopts the above value of R_0 and recent
determination of V_sun ~ 12 km/s.Comment: 14 pages, 6 figures, PASJ in pres
Age-related decrease of miRNA-92a levels in human CD8+ T-cells correlates with a reduction of naïve T lymphocytes
MicroRNA (miR)-17-92a expression plays a crucial role in lymphocyte ontogeny. We therefore set out to determine miR-92a expression levels in peripheral blood lymphocytes from healthy subjects to ascertain any association between these levels and ageing. We found a positive correlation between the miR-92a expression level and the percentages of RO-CD8+CD27+ (P = 0.0046) and CD3+CD8+CD62L+ (P = 0.0011). This suggests that the majority of miR-92a of CD8+ T cells is derived from naïve cells, and the miR-92a expression level in CD8+ T cells declines progressively with age. These results indicate that the age-related attrition of naïve T cells is linked to a reduction of miR-92a in human T -lymphocytes. Therefore, we should careful attention when evaluating human miRNA levels in T lymphocytes to use normal control values
VLBI Astrometry of AGB Variables with VERA -- A Semiregular Variable S Crateris --
We present a distance measurement for the semiregular variable S Crateris (S
Crt) based on its annual parallax. With the unique dual beam system of the VLBI
Exploration for Radio Astrometry (VERA) telescopes, we measured the absolute
proper motion of a water maser spot associated with S Crt, referred to the
quasar J1147-0724 located at an angular separation of 1.23. In
observations spanning nearly two years, we have detected the maser spot at the
LSR velocity of 34.7 km s, for which we measured the annual parallax of
2.330.13 mas corresponding to a distance of 430 pc. This
measurement has an accuracy one order of magnitude better than the parallax
measurements of HIPPARCOS. The angular distribution and three-dimensional
velocity field of maser spots indicate a bipolar outflow with the flow axis
along northeast-southwest direction. Using the distance and photospheric
temperature, we estimate the stellar radius of S Crt and compare it with those
of Mira variables.Comment: 9 pages, 4 figures, accepted for publication in PASJ (Vol.60, No.5,
October 25, VERA special issue
Calreticulin and integrin alpha dissociation induces anti-inflammatory programming in animal models of inflammatory bowel disease
Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease, is a chronic intestinal inflammatory condition initiated by integrins-mediated leukocyte adhesion to the activated colonic microvascular endothelium. Calreticulin (CRT), a calcium-binding chaperone, is known as a partner in the activation of integrin α subunits (ITGAs). The relationship between their interaction and the pathogenesis of IBD is largely unknown. Here we show that a small molecule, orally active ER-464195-01, inhibits the CRT binding to ITGAs, which suppresses the adhesiveness of both T cells and neutrophils. Transcriptome analysis on colon samples from dextran sodium sulfate-induced colitis mice reveals that the increased expression of pro-inflammatory genes is downregulated by ER-464195-01. Its prophylactic and therapeutic administration to IBD mouse models ameliorates the severity of their diseases. We propose that leukocytes infiltration via the binding of CRT to ITGAs is necessary for the onset and development of the colitis and the inhibition of this interaction may be a novel therapeutic strategy for the treatment of IBD
Astrometry of HO Masers in Nearby Star-Forming Regions with VERA. III. IRAS 22198+6336 in L1204G
We present results of multi-epoch VLBI observations with VERA (VLBI
Exploration of Radio Astrometry) of the 22 GHz HO masers associated with
a young stellar object (YSO) IRAS 22198+6336 in a dark cloud L1204G. Based on
the phase-referencing VLBI astrometry, we derive an annual parallax of IRAS
22198+6336 to be 1.3090.047 mas, corresponding to the distance of
76427 pc from the Sun. Although the most principal error source of our
astrometry is attributed to the internal structure of the maser spots, we
successfully reduce the errors in the derived annual parallax by employing the
position measurements for all of the 26 detected maser spots. Based on this
result, we reanalyze the spectral energy distribution (SED) of IRAS 22198+6336
and find that the bolometric luminosity and total mass of IRAS 22198+6336 are
450 and 7, respectively. These values are consistent with
an intermediate-mass YSO deeply embedded in the dense dust core, which has been
proposed to be an intermediate-mass counterpart of a low-mass Class 0 source.
In addition, we obtain absolute proper motions of the HO masers for the
most blue-shifted components. We propose that the collimated jets aligned along
the east-west direction are the most plausible explanation for the origin of
the detected maser features.Comment: 15 pages, 7 figures, accepted for publication in PASJ (Vol.60, No.5,
October 25, VERA special issue