182 research outputs found
XAFS Measurement System in the Soft X-ray Region for Various Sample Conditions and Multipurpose Measurements
Proliferative Potential of a Spinal Nephroblastoma in a Young Dog
The proliferative potential of a spinal nephroblastoma was studied in a young dog. A 4-month-old, female golden retriever showed developing deterioration in her gait and subsequent paralysis of her hind legs. At necropsy, a well-demarcated grayish brown tumor mass was found in the lumbar spinal cord segments between L2 and L3. Histologically, a blastemal cell tumor with a tubule- or glomeruli-like structure was found to be infiltrating intradurally. Proliferating cells at the S-phase, assessed using the bromodeoxyuridine (BrdU) labeling method, were seen occasionally in the tubular cells and glomeruli-like structures and were frequently seen in the blastemal cells. Immunohistochemically, the tubular epithelial cells were positive for cytokeratin, and the blastemal cells were positive for vimentin. The present tumor showed a high potential for growth and invasion, which suggests that it the potential to expand into the adjacent spinal cord
Red fluorescent cAMP indicator with increased affinity and expanded dynamic range
cAMP is one of the most important second messengers in biological processes. Cellular dynamics of cAMP have been investigated using a series of fluorescent indicators; however, their sensitivity was sub-optimal for detecting cAMP dynamics at a low concentration range, due to a low ligand affinity and/or poor dynamic range. Seeking an indicator with improved detection sensitivity, we performed insertion screening of circularly permuted mApple, a red fluorescent protein, into the cAMP-binding motif of PKA regulatory subunit Iα and developed an improved cAMP indicator named R-FlincA (Red Fluorescent indicator for cAMP). Its increased affinity (Kd = 0.3 μM) and expanded dynamic range (860% at pH 7.2) allowed the detection of subtle changes in the cellular cAMP dynamics at sub-μM concentrations, which could not be easily observed with existing indicators. Increased detection sensitivity also strengthened the advantages of using R-FlincA as a red fluorescent indicator, as it permits a series of applications, including multi-channel/function imaging of multiple second messengers and combinatorial imaging with photo-manipulation. These results strongly suggest that R-FlincA is a promising tool that accelerates cAMP research by revealing unobserved cAMP dynamics at a low concentration range
On the Nature of AX J2049.6+2939 and AX J2050.0+2914
AX J2049.6+2939 is a compact X-ray source in the vicinity of the southern
blow-up region of the Cygnus Loop supernova remnant (Miyata et al. 1998a). This
source was the brightest X-ray source inside the
Cygnus Loop observed during the ASCA survey project. The X-ray spectrum was
well fitted by a power-law function with a photon index of . Short-term timing analysis was performed and no coherent pulsation
was found. Follow-up observations with ASCA have revealed a large variation in
X-ray intensity by a factor of 50, whereas the spectral shape did not
change within the statistical uncertainties. In the second ASCA observation, we
found another X-ray source, AX J2050.0+2941, at the north east of AX
J2049.6+2939. During the three ASCA observations, the X-ray intensity of AX
J2050.0+2941 varied by a factor of 4. No coherent pulsations could be
found for AX J2050.0+2941.
We have performed optical photometric and spectroscopic observations in the
vicinity of AX J2049.6+2939 at the Kitt Peak National Observatory
(KPNO). As a result, all objects brighter than -band magnitude of 22 in
the error box can be identified with normal stars. Combined with the
X-ray results and the fact that there are no radio counterparts, AX
J2049.6+2939 is not likely to be either an ordinary rotation-powered pulsar
or an AGN. The nature of AX J2049.6+2939 is still unclear and further
observations over a wide energy band are strongly required.
As to AX J2050.0+2941, the long-term X-ray variability and the radio
counterpart suggests that it is an AGN.Comment: 23 pages, 4 figures, Accepted for publication by Astrophysical
Journa
Ultrafast relaxation processes of excitons to the relaxed excited state in one-dimensional dimethylglyoxime platinum complexes driven by intramolecular vibration
Non-Abelian Vortices on Cylinder -- Duality between vortices and walls
We investigate vortices on a cylinder in supersymmetric non-Abelian gauge
theory with hypermultiplets in the fundamental representation. We identify
moduli space of periodic vortices and find that a pair of wall-like objects
appears as the vortex moduli is varied. Usual domain walls also can be obtained
from the single vortex on the cylinder by introducing a twisted boundary
condition. We can understand these phenomena as a T-duality among D-brane
configurations in type II superstring theories. Using this T-duality picture,
we find a one-to-one correspondence between the moduli space of non-Abelian
vortices and that of kinky D-brane configurations for domain walls.Comment: 33 pages, 17 figures, v2: references added, typos corrected, the
final version published in PR
Direct observation of reversible oxygen anion redox reaction in Li-rich manganese oxide, Li2MnO3, studied by soft X-ray absorption spectroscopy
Li-rich layered oxides have attracted attention as promising positive electrode materials for next-generation lithium-ion secondary batteries because of their high energy storage capacity. The participation of the oxygen anion has been hypothesized to contribute to these oxides' high capacity. In the present study, we used O K-edge and Mn L-edge X-ray absorption spectroscopy (XAS) to study the reversible redox reactions that occur in single-phase Li-rich layered manganese oxide, Li2MnO3. We semiquantitatively analyzed the oxygen and manganese reactions by dividing the charge/discharge voltage region into two parts. The O K-edge XAS indicated that the electrons at the oxygen site reversibly contributed to the charge compensation throughout the charge/discharge processes at operating voltages between 2.0 and 4.8 V vs. Li+/Li0. The Mn L-edge XAS spectra indicated that the Mn redox reaction occurred only in the lower-voltage region. Thus, at higher potentials, the electrons, mainly at the oxygen site, contributed to the charge compensation. Peaks whose energies were similar to peroxide appeared in and then disappeared from the O K-edge spectra obtained during the reversible redox cycles. These results indicate that the reorganization of the oxygen network in the crystal structure affects the redox components. By using two kinds of detection modes with different probing depths in XAS measurements, it was found that these redox reactions are bulk phenomena in the electrode
Statistical Mechanics of Vortices from D-branes and T-duality
We propose a novel and simple method to compute the partition function of
statistical mechanics of local and semi-local BPS vortices in the Abelian-Higgs
model and its non-Abelian extension on a torus. We use a D-brane realization of
the vortices and T-duality relation to domain walls. We there use a special
limit where domain walls reduce to gas of hard (soft) one-dimensional rods for
Abelian (non-Abelian) cases. In the simpler cases of the Abelian-Higgs model on
a torus, our results agree with exact results which are geometrically derived
by an explicit integration over the moduli space of vortices. The equation of
state for U(N) gauge theory deviates from van der Waals one, and the second
virial coefficient is proportional to 1/sqrt{N}, implying that non-Abelian
vortices are "softer" than Abelian vortices. Vortices on a sphere are also
briefly discussed.Comment: 20 pages, 18 figure
Intersecting Solitons, Amoeba and Tropical Geometry
We study generic intersection (or web) of vortices with instantons inside,
which is a 1/4 BPS state in the Higgs phase of five-dimensional N=1
supersymmetric U(Nc) gauge theory on R_t \times (C^\ast)^2 \simeq R^{2,1}
\times T^2 with Nf=Nc Higgs scalars in the fundamental representation. In the
case of the Abelian-Higgs model (Nf=Nc=1), the intersecting vortex sheets can
be beautifully understood in a mathematical framework of amoeba and tropical
geometry, and we propose a dictionary relating solitons and gauge theory to
amoeba and tropical geometry. A projective shape of vortex sheets is described
by the amoeba. Vortex charge density is uniformly distributed among vortex
sheets, and negative contribution to instanton charge density is understood as
the complex Monge-Ampere measure with respect to a plurisubharmonic function on
(C^\ast)^2. The Wilson loops in T^2 are related with derivatives of the Ronkin
function. The general form of the Kahler potential and the asymptotic metric of
the moduli space of a vortex loop are obtained as a by-product. Our discussion
works generally in non-Abelian gauge theories, which suggests a non-Abelian
generalization of the amoeba and tropical geometry.Comment: 39 pages, 11 figure
- …