578 research outputs found
CMOS Voltage and Current Reference Circuits consisting of Subthreshold MOSFETs – Micropower Circuit Components for Power-Aware LSI Applications –
Chandra Observations of a Non-Thermal Supernova Remnant Candidate AX J1843.8-0352 and its Surroundings
We present the Chandra results of AX J1843.8-0352, a supernova remnant (SNR)
recently identified with ASCA. Chandra spatially resolved two components from
this SNR: non-thermal and thermal ones. The morphology of the non-thermal
component is clumpy and elliptical, elongated from the north to the south with
a mean diameter of about 9 arcmin. The spectrum is fitted with a power-law
model of photon index 2.1 and the east rim is associated with the non-thermal
radio sources C and F (Helfand et al. 1989). Therefore the non-thermal
component is probably synchrotron X-rays by energetic electrons accelerated at
the shell of the SNR. The thermal component is the brightest clump located
within the non-thermal component and shows a spectrum of a thin plasma of about
0.7 keV temperature. Notable discovery is its peculiar morphology; a head of 50
arcsec x 30 arcsec size near the south-east rim of the SNR and a 30 arcsec-long
``jet'' pointing to the southwest. Although this emission is associated with
the west part of the radio source F, the absorption is twice larger than that
of the non-thermal X-rays, or the bulk of the SNR emission. Therefore, it is
unclear whether this peculiar plasma is a thermal component associated with AX
J1843.8-0352, a Galactic source located in the far side of our Galaxy, or an
extragalactic source.Comment: 19 pages, 5 figures; to appear in Ap
Climatological analysis on extratropical cyclones in the middle latitudes of the Northern Hemisphere
Thesis--University of Tsukuba, D.Sc.(A), no. 876, 1991. 3. 2
Observations of Chromospheric Anemone Jets with Hinode SOT and Hida Ca II Spectroheliogram
We present the first simultaneous observations of chromospheric "anemone"
jets in solar active regions with Hinode SOT Ca II H broadband filetergram and
Ca II K spetroheliogram on the Domeless Solar Telescope (DST) at Hida
Observatory. During the coordinated observation, 9 chromospheric anemone jets
were simultaneously observed with the two instruments. These observations
revealed three important features, i.e.: (1) the jets are generated in the
lower chromosphere, (2) the length and lifetime of the jets are 0.4-5 Mm and
40-320 sec, (3) the apparent velocity of the jets with Hinode SOT are 3-24
km/s, while Ca II K3 component at the jets show blueshifts (in 5 events) in the
range of 2- 6 km/s. The chromospheric anemone jets are associated with mixed
polarity regions which are either small emerging flux regions or moving
magnetic features. It is found that the Ca II K line often show red or blue
asymmetry in K2/K1 component: the footpoint of the jets associated with
emerging flux regions often show redshift (2-16 km/s), while the one with
moving magnetic features show blueshift (around 5 km/s). Detailed analysis of
magnetic evolution of the jet foaming regions revealed that the reconnection
rate (or canceling rate) of the total magnetic flux at the footpoint of the
jets are of order of 10^{16} Mx/s, and the resulting magnetic energy release
rate (1.1-10) x 10^{24} erg/s, with the total energy release (1-13) x 10^{26}
erg for the duration of the magnetic cancellations, 130s. These are comparable
to the estimated total energy, 10^{26} erg, in a single chromospheric anemone
jet. An observation-based physical model of the jet is presented. The relation
between chromospheric anemone jets and Ellerman bombs is discussed.Comment: 22 pages, 27 figures, accepted for Publications of the Astronomical
Society of Japa
Method for Assessing X-ray-Induced Hydroxyl Radical Scavenging Activity of Biological Compounds/Materials
A method for correctly assessing hydroxyl radical scavenging activity of antioxidative chemicals and/or biological compounds/materials was proposed. This method can simultaneously assess two factors, i.e. hydroxyl radical scavenging and 5,5-dimethyl-2-hydroxy-1-pyrrolidine-N-oxide (hydroxyl radical adduct of 5,5-dimethyl-1-pyrroline-N-oxide) reducing ability, as antioxidative properties. In this paper, some biologically common hydrophilic molecules, cell culture media, and rat plasma were tested. X-ray induced hydroxyl radical can be detected using the electron paramagnetic resonance spin trapping technique. Using X-ray irradiation of the reaction mixture as the hydroxyl radical source, the true hydroxyl radical scavenging ability of the subjected antioxidant can be assessed. In addition, the method simultaneously measures the reduction of 5,5-dimethyl-2-hydroxy-1-pyrrolidine-N-oxide, to estimate the reducing ability of the antioxidant. Biological materials, such as sugars and proteins, could abolish hydroxyl radical at the biological concentration. Ascorbic acid showed reducing ability at the biological concentration. The simultaneous assessment of hydroxyl radical scavenging and reducing ability of antioxidants can be an informative index for antioxidants
Trial of Brain Redox Imaging and Estimation of Radiation-Induced Redox Change in Mouse Brain
The in vivo T1-weighted contrasting abilities and signal decay behaviors of several nitroxyl contrast agents, which have been used as redox responsive contrast agents in several magnetic resonance-based imaging modalities, in mouse brain were compared. In addition, daily variations of redox behavior in mouse brain after irradiation of X-ray or carbon-ion beams (C-beam) were tried to estimate based on the in vivo reduction rate of amphiphilic nitroxyl contrast agents.Injection solutions of five types of five-membered-ring nitroxyl contrast agents, i.e. 3-carboxy-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CxP), 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CmP), 3-methoxy-carbonyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (MCP), acetoxymethyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl-3-carboxylate (CxP-AM), and 4-(N-methylpiperidine)-2,2,5,5-tetramethylpyrroline-N-oxyl (23c), and a six-membered-ring nitroxyl contrast agent, i.e. 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL), were prepared. The nitroxyl contrast agent was i.v. injected to a mouse through tail vein. Then, the distributions and pharmacokinetics of nitroxyl contrast agents were compared based on the time course of T1-weighted MRI. The MRI experiments using CMP or TEMPOL were repeated for mice irradiated by X-ray or C-beam to their head on several deferent timings, i.e. 1, 2, 4, 8 day(s) after irradiation. C-beam was irradiated at Heavy-Ion Medical Accelerator in Chiba (HIMAC, National Institute of Radiological Sciences/ National Institutes for Quantum and Radiological Science and Technology).The blood-brain-barrier (BBB)-impermeable CxP could not be distributed in the brain. The slightly lipophilic CmP showed slight distribution only in the ventricle, but not in the medulla and cortex. The amphiphilic MCP and TEMPOL had good initial uniform distribution in the brain and showed typical 2-phase signal decay profiles. A brain-seeking nitroxyl probe, CxP-AM, showed an accumulating phase, and then its accumulation was maintained in the medulla and ventricle regions, but not in the cortex. The lipophilic 23c was well distributed in the cortex and medulla, but slightly in the ventricle, and showed relatively rapid linear signal decay.Decay rates of MCP in mouse brain after irradiation of 8 Gy X-ray, 8 Gy C-beam or 16 Gy C-beams did not show marked clear changes, however relatively little decreasing were observed at day 1 and day 2 after irradiation. Decay rates of TEMPOL was increased 1 after irradiation then gradually recovered to the control level. MCP and TEMPOL showed opposite responses but the timing of redox change may be 1 or 2 days after irradiation.Nitroxyl contrast agents equipped with a suitable lipophilic substitution group could be BBB-permeable functional contrast agents. MR redox imaging, which can estimate not only the redox characteristics but also the detailed distribution of the contrast agents, is a good candidate for a theranostic tool. Irradiation of ionized radiation to head could cause alternation of redox status in the brain. Detail of redox mechanisms were still in progress.第7回国際放射線神経生物学会大
Inter-annual and intra-seasonal variations of mountain weather in Khumbu region, Nepal Himalayas (Session 3: In-site Flux Observation studies)
Domain distributions in tetragonal Pb(Zr,Ti)O3 thin films probed by polarized Raman spectroscopy
We have investigated polarized Raman spectra of (001)/(100)-oriented tetragonal epitaxial Pb(ZrxTi1–x)O3 (PZT) thin films (x=~0.35) in which the volume fraction of the polar c domain is systematically varied from 4% to 96%. From polarization analyses using high epitaxial quality films, we have successfully isolated the A1 and B1 phonons from the E phonons, thus offering a distinctive evaluation of the c domains. As increasing c-domain volume, the A1(TO) modes linearly increase in their intensity. A remarkable correlation is found between the A1(1TO)-mode intensity and the c-domain volume for PZT films. We suggest that this correlation as well as the A1(1TO)-mode intensity provide a simple and useful probe for characterization of c-domain volume and ferroelectric properties in PZT-based devices
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