Characterization of metal-insulator-semicomductor capacitors with insulating nitride films grown on 4H-SiC

ArticleJAPANESE JOURNAL OF APPLIED PHYSICS. 47(1):676-678(2008)journal articl

Orbits in the Field of a Gravitating Magnetic Monopole

Orbits of test particles and light rays are an important tool to study the properties of space-time metrics. Here we systematically study the properties of the gravitational field of a globally regular magnetic monopole in terms of the geodesics of test particles and light. The gravitational field depends on two dimensionless parameters, defined as ratios of the characteristic mass scales present. For critical values of these parameters the resulting metric coefficients develop a singular behavior, which has profound influence on the properties of the resulting space-time and which is clearly reflected in the orbits of the test particles and light rays.Comment: 24 pages, 15 figures. Accepted for publication in GR

Circadian Gene Circuitry Predicts Hyperactive Behavior in a Mood Disorder Mouse Model

SummaryBipolar disorder, also known as manic-depressive illness, causes swings in mood and activity levels at irregular intervals. Such changes are difficult to predict, and their molecular basis remains unknown. Here, we use infradian (longer than a day) cyclic activity levels in αCaMKII (Camk2a) mutant mice as a proxy for such mood-associated changes. We report that gene-expression patterns in the hippocampal dentate gyrus could retrospectively predict whether the mice were in a state of high or low locomotor activity (LA). Expression of a subset of circadian genes, as well as levels of cAMP and pCREB, possible upstream regulators of circadian genes, were correlated with LA states, suggesting that the intrinsic molecular circuitry changes concomitant with infradian oscillatory LA. Taken together, these findings shed light onto the molecular basis of how irregular biological rhythms and behavior are controlled by the brain

Performance of the neutron polarimeter NPOL3 for high resolution measurements

We describe the neutron polarimeter NPOL3 for the measurement of polarization transfer observables $D_{ij}$ with a typical high resolution of $\sim$300 keV at $T_n$ $\simeq$ 200 MeV. The NPOL3 system consists of three planes of neutron detectors. The first two planes for neutron polarization analysis are made of 20 sets of one-dimensional position-sensitive plastic scintillation counters with a size of 100 cm $\times$ 10 cm $\times$ 5 cm, and they cover the area of 100 $\times$ 100 $\mathrm{cm}^2$. The last plane for detecting doubly scattered neutrons or recoiled protons is made of the two-dimensional position-sensitive liquid scintillation counter with a size of 100 cm $\times$ 100 cm $\times$ 10 cm. The effective analyzing powers $A_{y;\mathrm{eff}}$ and double scattering efficiencies $\epsilon_{\mathrm{D.S.}}$ were measured by using the three kinds of polarized neutrons from the ${}^{2}{\rm H}(\vec{p},\vec{n})pp$, ${}^{6}{\rm Li}(\vec{p},\vec{n}){}^{6}{\rm Be}(\mathrm{g.s.})$, and ${}^{12}{\rm C}(\vec{p},\vec{n}){}^{12}{\rm N}(\mathrm{g.s.})$ reactions at $T_p$ = 198 MeV. The performance of NPOL3 defined as $\epsilon_{\mathrm{D.S.}}(A_{y;\mathrm{eff}})^2$ are similar to that of the Indiana Neutron POLarimeter (INPOL) by taking into account for the counter configuration difference between these two neutron polarimeters.Comment: 28 pages, 18 figures, submitted to Nucl. Instrum. Methods Phys. Res.

Energy Spectra of the Soft X-ray Diffuse Emission in Fourteen Fields Observed with Suzaku

The soft diffuse X-ray emission of twelve fields observed with Suzaku are presented together with two additional fields from previous analyses. All have galactic longitudes 65 deg < l < 295 deg to avoid contributions from the very bright diffuse source that extends at least 30 deg from the Galactic center. The surface brightnesses of the Suzaku nine fields for which apparently uncontaminated ROSAT All Sky Survey (RASS) were available were statistically consistent with the RASS values, with an upper limit for differences of 17 x 10^{-6} c s^{-1} amin^{-2} in R45}-band. The Ovii and Oviii intensities are well correlated to each other, and Ovii emission shows an intensity floor at ~2 photons s^{-1} cm^{-2 str^{-1} (LU). The high-latitude Oviii emission shows a tight correlation with excess of Ovii emission above the floor, with (Oviii intensity) = 0.5 x [(Ovii intensity) -2 LU], suggesting that temperatures averaged over different line-of-sight show a narrow distribution around ~0.2 keV. We consider that the offset intensity of Ovii arises from the Heliospheric solar wind charge exchange and perhaps from the local hot bubble, and that the excess Ovii (2-7 LU) is emission from more distant parts of the Galaxy. The total bolometric luminosity of this galactic emission is estimated to be 4 x 10^{39} erg s^{-1}, and its characteristic temperature may be related to the virial temperature of the Galaxy.Comment: 22 Pages, 8 figures, to appear in PASJ (Vol.61 No.4

X-ray and UV spectroscopy of Galactic diffuse hot gas along the LMC X--3 sight line

We present Suzaku spectra of X-ray emission in the fields just off the LMC X-3 sight line. OVII, OVIII, and NeIX emission lines are clearly detected, suggesting the presence of an optically thin thermal plasma with an average temperature of 2.4E6. This temperature is significantly higher than that inferred from existing X-ray absorption line data obtained with Chandra grating observations of LMC X-3, strongly suggesting that the gas is not isothermal. We then jointly analyze these data to characterize the spatial and temperature distributions of the gas. Assuming a vertical exponential Galactic disk model, we estimate the gas temperature and density at the Galactic plane and their scale heights as 3.6(2.9, 4.7)E6 K and 1.4(0.3, 3.4)E-3 cm^{-3} and 1.4(0.2, 5.2) kpc and $2.8(1.0, 6.4)$ kpc, respectively. This characterization can account for all the \ovi line absorption, as observed in a FUSE spectrum of LMC X-3, but only predicts less than one tenth of the OVI line emission intensity typically detected at high Galactic latitudes. The bulk of the OVI emission most likely arises at interfaces between cool and hot gases.Comment: 10 pages, 7 figures, 3 tables, accepted for publication in ApJ, 200

Breakdown of supersaturation barrier links protein folding to amyloid formation

The thermodynamic hypothesis of protein folding, known as the “Anfinsen’s dogma” states that the native structure of a protein represents a free energy minimum determined by the amino acid sequence. However, inconsistent with the Anfinsen’s dogma, globular proteins can misfold to form amyloid fibrils, which are ordered aggregates associated with diseases such as Alzheimer’s and Parkinson’s diseases. Here, we present a general concept for the link between folding and misfolding. We tested the accessibility of the amyloid state for various proteins upon heating and agitation. Many of them showed Anfinsen-like reversible unfolding upon heating, but formed amyloid fibrils upon agitation at high temperatures. We show that folding and amyloid formation are separated by the supersaturation barrier of a protein. Its breakdown is required to shift the protein to the amyloid pathway. Thus, the breakdown of supersaturation links the Anfinsen’s intramolecular folding universe and the intermolecular misfolding universe

Energetic Components of Cooperative Protein Folding

A new lattice protein model with a four-helix bundle ground state is analyzed by a parameter-space Monte Carlo histogram technique to evaluate the effects of an extensive variety of model potentials on folding thermodynamics. Cooperative helical formation and contact energies based on a 5-letter alphabet are found to be insufficient to satisfy calorimetric and other experimental criteria for two-state folding. Such proteinlike behaviors are predicted, however, by models with polypeptide-like local conformational restrictions and environment-dependent hydrogen bonding-like interactions.Comment: 11 pages, 4 postscripts figures, Phys. Rev. Lett. (in press