Effect of posterior hypothalamic knife cuts on the baroreflex and hemorrhage-induced hormonal responses.

We made posterior hypothalamic knife cuts in rats to transect the fibers of the medial forebrain bundle (MFB) at the level of the mammillary body. The role of the MFB in the baroreflex and hemorrhage-induced hormonal responses was then examined in the unanesthetized, freely moving condition. The slopes for the relationship between changes in pulse interval and mean arterial pressure (MAP) in the posterior-cut group were significantly steeper than those in the sham-cut group both when there were phenylephrine-induced increases in MAP (1.13 +/- 0.07 vs 0.86 +/- 0.10 msec/mmHg) and nitroprusside-induced decreases in MAP (1.16 +/- 0.10 vs 0.77 +/- 0.05 msec/mmHg). This result indicates that posterior cuts elevated baroreflex sensitivity when MAP was increased or decreased. The resting MAP was not changed, but the resting heart rate (HR) was lowered by the posterior cuts. Furthermore, the posterior cuts augmented hypotensive hemorrhage-induced bradycardia. Hypotensive hemorrhage (16-17 ml/kg) caused elevation of the plasma catecholamine, ACTH and vasopressin (AVP) levels, but the posterior cuts attenuated these hormonal responses. These results indicate that the fibers in the MFB have a tonic inhibitory effect on the baroreflex in the resting condition, and play a stimulatory role in hemorrhage-induced catecholamine, ACTH and AVP responses.</p

Diffuse X-Ray Scattering Measurement by Stationary Use of the Buerger Precession Camera

A photographic method for constructing the intensity contours of the diffuse X-ray scattering from a series of stationary photographs taken with the crystal and film rotated through successive angles is proposed, which is efficient for detecting the details of the intensity distribution. The transformation equations are derived to relate the coordinates on the film to those in the reciprocal lattice. A volume element of intensity measurement in reciprocal space, necessary for obtaining the integrated intensity or calculating the Fourier transforms of the intensity, is calculated

Evolution of 3-9 Mo Stars for Z=0.001 - 0.03 and Metallicity Effects on Type Ia Supernovae

Recent observations have revealed that Type Ia supernovae (SNe Ia) are not perfect standard candles but show some variations in their absolute magnitudes, light curve shapes, and spectra. The C/O ratio in the SNe Ia progenitors (C-O white dwarfs) may be related to this variation. In this work, we systematically investigate the effects of stellar mass (M) and metallicity (Z) on the C/O ratio and its distribution in the C-O white dwarfs by calculating stellar evolution from the main-sequence through the end of the second dredge-up for M=3-9 Mo and Z=0.001-0.03. We find that the total carbon mass fraction just before SN Ia explosion varies in the range 0.36 -- 0.5. We also calculate the metallicity dependence of the main-sequence-mass range of the SN Ia progenitor white dwarfs. Our results show that the maximum main-sequence mass to form C-O white dwarfs decreases significantly toward lower metallicity, and the number of SN Ia progenitors may be underestimated if metallicity effectis neglected. We discuss the implications of these results on the variation of SNe Ia, determination of cosmological parameters, luminosity function of white dwarfs, and the galactic chemical evolution.Comment: Added references and corrected typos. To appear in the Astrophysical Journal 1999 March 10 issu

Electron Diffraction Study on Diffuse Scattering from Disordered Cu_3Au Alloy

A detailed study has been made on diffuse scattering from Cu_3Au alloy in the disordered state by electron diffraction, using single crystal evaporated films, in order to investigate the origin of the short-range order above T_c. Aspects of the diffuse scattering resemble in some respects those of superlattice reflections below T_c, which are related to the antiphase domain structure. From the present study, however, it has become clear that there is no direct relation between the short-range order state above Te and the antiphase domain structure below T_c. Behaviors of the diffuse scattering have been studied, the electron-atom ratio being changed by addition of Pd or In to Cu_3Au. Results obtained are well interpreted by the suggestion of Moss, indicating that the short-range order state revealed by the diffuse scattering originates from anomalies of energy of conduction electrons

Correlative Microdomain Model for Short-Range Ordered Alloy Structures : I. Diffraction Theory(Physics)

A diffraction theory is developed for diffuse scattering from disordered binary alloys with short-range order. It is based on a model of ordered microdomains embedded in a disordered matrix and interference effects between the domains are considered. There is a possibility that the fine structures of diffuse scattering as observed in the cases of Cu_3Au, CuAu and Cu_3Pd alloys result from the introduction of interdomain correlations. From experimental diffuse intensity values one can calculate the statistical distribution of microdomains in antiphase with one another

X-ray Diffraction Study of Static Distortion of the Host Zirconium Lattice in Interstitial Zr-O Solid Solutions(Physics)

Static distortions of the host zirconium lattice as caused by the interstitial oxygen atoms have been determined by X-ray diffraction for Zr-23.6 and 24.8 at.%O alloys. The arrangement of oxygen atoms in the former alloy is specified by the ZrO_x or ABC-type stacking structure and that in the latter by a statistical sequence of two kinds of oxygen layer, i.e. single A and double AB layers. The present work has proved that each zirconium atom shifts toward the adjacent oxygen atoms and the magnitude of the displacement is about 0.04 A for both the alloys. The anomalous dependence of the lattice constants on oxygen concentration is qualitatively explained by the local contraction in the c plane

Nucleosynthesis in ONeMg Novae: Models versus Observations to Constrain the Masses of ONeMg White Dwarfs and Their Envelopes

Nucleosynthesis in ONeMg novae has been investigated with the wide ranges of three parameters, i.e., the white dwarf mass, the envelope mass at ignition, and the initial composition. A quasi-analytic one-zone approach is used with an up-to-date nuclear reaction network. The nucleosynthesis results show correlation with the peak temperatures or the cooling timescales during outbursts. Among the combinations of white dwarf and envelope masses which give the same peak temperature, the explosion is more violent for a lower white dwarf mass owing to its smaller gravitational potential. Comparison of the nucleosynthesis results with observations implies that at least two-third of the white dwarf masses for the observed ONeMg novae are $\simeq 1.1 M_\odot$, which are significantly lower than estimated by previous hydrodynamic studies but consistent with the observations of V1974 Cyg. Moreover, the envelope masses derived from the comparison are $\gtrsim 10^{-4} M_\odot$, which are in good agreement with the ejecta masses estimated from observations but significantly higher than in previous hydrodynamic studies. With such a low mass white dwarf and a high mass envelope, the nova can produce interesting amounts of $\gamma$-ray emitters $^7$Be, $^{22}$Na, and $^{26}$Al. We suggest that V1974 Cyg has produced $^{22}$Na as high as the upper limit derived from the COMPTEL survey. In addition, a non-negligible part of the Galactic $^{26}$Al may originate from ONeMg novae, if not the major contributors. Both the future INTEGRAL survey for these $\gamma$-ray emitters and abundance estimates derived from ultraviolet, optical, and near infrared spectroscopies will impose a severe constraint on the current nova models.Comment: 21 pages, 23 figures, to appear in the Astrophysical Journal, Vol. 523, No.1, September 20, 1999; preprint with embedded images can be obtained from http://th.nao.ac.jp/~wanajo/journal/onenova.p

Plasmonic-Heating-Induced Nanoscale Phase Separation of Free Poly(N-isopropylacrylamide) Molecules

The localized-surface-plasmon resonance (LSPR) of gold nanoparticles (Au NPs) depends sensitively on the environmental refractive index. We found that LSPRs of single Au NPs supported on a transparent substrate can monitor the phase transition/separation of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) in aqueous solution. Both reversible and irreversible phase separations were observed. Plasmonic-heating-induced redshifts and subsequent cooling-induced recovery were observed on a glass substrate. Besides reversible redshifts at lower laser intensities, permanent redshifts were evident at higher intensities after illumination on a sapphire substrate, which has a much higher thermal conductivity than glass. The permanent redshifts were caused by the formation of a PNIPAM shell around the NP. For this permanent aggregation, temperature shaping around the Au NP by the substrate was found decisive and may find new chemistry applications based on local temperature landscapes. The observed nanofabrication of core–shell particles is one such example

HLA-DRB1 and DQB1 alleles in Japanese type 1 autoimmune hepatitis: The predisposing role of the DR4/DR8 heterozygous genotype

ObjectiveAutoimmune hepatitis (AIH) is a chronic progressive liver disease. AIH is composed predominantly of type 1 in Japanese populations. The genetic and environmental factors are associated with the pathogenesis of AIH. HLA-DRB1*03:01 and *04:01 are associated with type 1 AIH in European and *04:05 in Japanese populations. Here, we conducted an HLA association study in order to find HLA alleles or haplotypes predisposing or protective for Japanese AIH.MethodsHLA-DRB1 and DQB1 genotyping of 360 type 1 AIH patients and 1026 healthy controls was performed.ResultsThe predisposing association of DRB1*04:01 (P = 0.0006, corrected P [Pc] = 0.0193, odds ratio [OR] 2.97, 95% confidence interval [CI] 1.62–5.43), DRB1*04:05 (P = 1.89×10−21, Pc = 5.86×10−20, OR 3.41, 95% CI 2.65–4.38), and DQB1*04:01 (P = 4.66×10−18, Pc = 6.99×10−17, OR 3.89, 95% CI 2.84–5.33) and the protective association of DRB1*13:02 (P = 0.0003, Pc = 0.0080, OR 0.48, 95% CI 0.32–0.72) with Japanese type 1 AIH were observed. An association of the DR4/DR8 heterozygous genotype with Japanese AIH was identified for the first time (P = 3.12×10−9, OR 3.52, 95% CI 2.34–5.29). Susceptible diplotypes were DRB1*04:05-DQB1*04:01/DRB1*08:02-DQB1*03:02 (P = 0.0004, OR 24.77, 95% CI 1.45–424.31) and DRB1*04:05-DQB1*04:01/DRB1*08:03-DQB1*06:01 (P = 1.18×10−6, OR 10.64, 95% CI 3.19–35.46). Serum levels of Immunoglobulin G and Immunoglobulin M, International Autoimmune Hepatitis Group score, positive rate of anti-smooth muscle antibodies, and the rate of definite AIH were higher in AIH patients with DRB1*04:05 than without.ConclusionsThe important roles of specific combinations of DRB1 and DQB1 alleles or haplotypes in the pathogenesis of type 1 AIH were suggested. The association of DR4/DR8 heterozygous genotype suggested the pathologic importance of trans-complementing DQα-β heterodimer molecules encoded by DQA1 allele of one haplotype and the DQB1 allele of the other haplotype, as it was proposed in the HLA association studies of Type 1 diabetes