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A new vibration apparatus for measuring the shear strength of snow has been designed and fabricated. The force applied to a snow block is calculated using Newton’s second law. Results from this apparatus concerning the dependence of the shear strength on snow density, overburden load and strain rate are in reasonable agreement with those obtained from the work of previous researchers. Snow densities ranged from 160 to 320 kg m−3. The overburden load and strain rate ranged from 1.95 × 10−1 to 7.79 × 10−1 kPa and 2.9 × 10−4 to 9.1 × 10−3 s−1 respectively.
Settlement force of a snow cover acting on horizontal beams O.8 m high on the ground has been measured using electric force gauges since winter 1974/75, to understand mechanisms of settlement force generation. Shapes of cross-sections of the beams were rectangular, square, equilateral triangle and triangular with a 37_ vertical angle. From the measurements, it was found that the magnitude of the settlement force acting on a beam did not depend upon the shape of cross-section when snow depth was smaller than 1.3 m, but in deeper snow it was smaller on the triangular than on the rectangular beam. When the surface of the snow cover turned into a crust, the settlement force increased from about 0.3 kN m-1 to 1.1 kN m-1. Physical properties of snow cover are important for quantitative estimation of the settlement force on a beam.
The average amounts of seasonal snow cover and snowfall in Japan were calculated as 7.9 × 1013kg and 1.2 × 1014kg, respectively. The mass of seasonal snow cover of a heavy-snowfall winter, 1980–81 (56-Gosetsu), was calculated as 1.3 × 1014kg. The amount of 7.9 × 1013kg was converted to water equivalent of 230 mm on the whole snow-covered area, including snow-prone area. A mean of 370 mm in snow water equivalent was calculated for the snow area where mean snow depth on the ground was more than 10 cm.
The startup dynamics of three wet snow avalanches in central Japan were evaluated by computer modeling the occurrences and comparing leading edge position-time data. Results were compared between three finite difference based computer codes, which were used to model the startup transients. Two of the computer codes use equations of uniform flow hydrodynamics, the third uses transient viscous fluid mechanics. The latter two codes also incorporate a material description of snow as a locking material. Results show a general increasing of frictional and/or viscous coefficients in the avalanche startup zones in order to match the kinematics of startup. Differences in results between the codes is attributed to the shape of the startup zones, whether convex or concave. The results indicate the magnitude of perturbation of startup on total avalanche runout time, which is likely to be negligible on long-duration avalanche occurrences.
Computer analysis is carried out to predict the force that bears upon a horizontal beam embedded in settling snowpack. Use is made of extensive experimental data on snow depth, layering and density, and on measured force on a test beam, in order to evaluate the internal structural arrangement in a finite element representation of the region in the vicinity of the beam. The compressive secondary-creep viscoelastic properties and the densification properties of the snow are accounted for in the computer modelling. Results show that the bearing force on the beam develop from direct snow weight, from shear transfer by adjacent snowpack, from basal weakening below and to the side of the beam, and from snow densification above and to the side of the beam producing a bridging mechanism. These findings corroborate with related experimental results and point out the need for further refinement in definition, particularly of the bridging mechanism, which produces large force incrementation on the beam compared to the other mechanisms noted.
In comparison with windward coral reefs, the facies and evolution of leeward coral reefs has been discussed to a lesser extent. By accelerator mass spectrometry (AMS) carbon-14 dating of coral specimens collected from the trench excavated across a modern coral reef during a fishery port repair, we revealed the internal facies and Holocene evolution of a leeward reef in Ishigaki Island, Ryukyu Islands, southwest Japan. The reef facies can be split into three facies: the tabular Acropora framework facies, the tabular Acropora reworked facies, and the unconsolidated bioclast facies. The tabular Acropora reworked facies first formed a ridge by 3500 BR Then, the tabular Acropora framework facies grew both upward and seaward. The accumulation rates of the tabular Acropora framework facies ranged from 2.2 to 8.3 m/ka. Thus, the reef framework facies and accumulation rates of this leeward reef is similar to those of windward reefs, although the age of the reef top is younger than that of windward reefs.
Higher daytime cortisol levels because of a hyperactive hypothalamic–pituitary–adrenal axis have been reported in patients with major depressive disorder (MDD). The elevated glucocorticoids inhibit the proliferation of the oligodendrocytes that are responsible for myelinating the axons of white matter fibre tracts.
To evaluate the relationship between white matter integrity and serum cortisol levels during a first depressive episode in drug-naive patients with MDD (MDD group) using a tract-based spatial statistics (TBSS) method.
The MDD group (n = 29) and a healthy control group (n = 47) underwent diffusion tensor imaging (DTI) scans and an analysis was conducted using TBSS. Morning blood samples were obtained from both groups for cortisol measurement.
Compared with the controls, the MDD group had significantly reduced fractional anisotropy values (P<0.05, family-wise error (FWE)-corrected) in the inferior fronto-occipital fasciculus, uncinate fasciculus and anterior thalamic radiation. The fractional anisotropy values of the inferior fronto-occipital fasciculus, uncinate fasciculus and anterior thalamic radiation had significantly negative correlations with the serum cortisol levels in the MDD group (P<0.05, FWE-corrected).
Our findings indicate that the elevated cortisol levels in the MDD group may injure the white matter integrity in the frontal–subcortical and frontal–limbic circuits.
Pr0.5Ca0.5MnO3 (PCMO) films were deposited on LaAlO3 (100) substrates under pressure from 1.33 to 5.33 Pa by RF magnetron sputtering. Resistance switching and dielectric functions of PCMO films were studied by DC current-voltage characteristic measurements and spectroscopic ellipsometry (SE) measurements. Resistance switching was observed in the devices composed of PCMO films deposited under low pressures of 1.33 and 2.67 Pa. SE measurements revealed that dielectric functions also depended on deposition pressure. PCMO films deposited under lower pressure had larger high-frequency dielectric constant, larger oscillator strength of the electric dipole charge transitions in MnO6 octahedral complexes, and lower oscillator strength of d-d transitions in Mn3+ and Mn4+ ions. SE measurements suggested that oxygen vacancies and MnO6 octahedral complexes play an important role in resistance switching in PCMO films.
The consumption of probiotics by pregnant and lactating women may prevent the onset of allergic disorders in their children by increasing the concentrations of immunoactive agents such as cytokines in breast milk. Prebiotics such as fructo-oligosaccharides (FOS) increase the number of beneficial organisms such as bifidobacteria. Thus, prebiotics may have an effect similar to that of probiotics. The objective of the present study was to carry out a comprehensive analysis of mRNA expression in human milk cells to identify changes in the concentrations of cytokines in breast milk after the consumption of FOS (4 g × 2 times/d) by pregnant and lactating women. The microarray analysis of human milk cells demonstrated that the expression levels of five genes in colostrum samples and fourteen genes in 1-month breast milk samples differed more than 3-fold between the FOS and control groups (sucrose group). The mRNA expression level of IL-27, a cytokine associated with immunoregulatory function, was significantly higher in 1-month breast milk samples obtained from the FOS group than in those obtained from the control group. In addition, the protein concentrations of IL-27 in colostrum and 1-month breast milk samples were significantly higher in the FOS group than in the control group. In conclusion, the consumption of FOS by pregnant and lactating women increases the production of IL-27 in breast milk. Future studies will address the association of this phenomenon with the onset of allergic disorders in children.
Bone-forming cells fabricate a highly ordered collagen matrix (osteoid) which subsequently mineralizes. A variety of cell culture systems exist for osteogenic cells, yet none of these is optimal for the organized formation of a mineralized matrix. We have generated collagen substrates which have different degrees of fibrillar orientation, and have cultured osteogenic cells on these matrices. In this format, von Kossa-stained sections show that highly oriented collagen matrix starts to calcify in 6–7 days, while a random fibrillar matrix does not mineralize even after 21 days. Mineral has been detected only within the collagen matrix with a narrow, unmineralized region between the cells and the mineral.
In this paper, we study contribution of the magnetoelastic anisotropy effect on perpendicular magnetic anisotropy of Co/Pt superlattice thin films. The effective-magnetic anisotropy energy was measured for Co/Pt thin films with a constant Co-layer thickness (4 Å) deposited on silicon substrate by the ultrahigh-vacuum deposition method. As the Pt-layer thickness increases, the effective-magnetic anisotropy energy increases and decreases after showing a maximum at the Pt-layer thickness of 12 Å. This behavior can be explained only by the magnetoelastic anisotropy effect, that is, elastic-strain energy released through the magnetostriction effect with the strain-dependent elastic constants.
We have carried out multi-epoch VLBI observations of the H2O maser sources associated with young stellar objects (YSOs) in nearby molecular clouds with VERA (VLBI Exploration of Radio Astrometry), which is a newly constructed VLBI network in Japan (Kobayashi et al. 2003). The main goal of our study is to measure the absolute proper motions and distances to nearby molecular clouds within 1 kpc from the Sun, to reveal their 3-dimensional structures and dynamical properties. Using the VERA dual-beam receiving system (Honma et al. 2003), we have carried out phase-referencing VLBI observations and measured annual parallaxes and absolute proper motions of the H2O maser features with respect to the extragalactic radio sources. We have successfully detected the annual parallax of one of the H2O maser features in Orion KL to be 2.29±0.10 mas, corresponding to the distance of 437±19 pc from the Sun (Hirota et al. 2007). In addition, the annual parallax of SVS13 in NGC 1333 is also determined to be4.10±0.17 mas, corresponding to the distance of 244±10 pc from the Sun, although the life time of the maser features are only 6 months. The absolute proper motions of the H2O maser features associated with Orion KL and NGC 1333 are derived, possibly indicating the outflow motions from the YSOs as well as the systemic motions of the powering sources.
The spectra of the Sloan Digital Sky Survey (SDSS) are being used to construct a catalogue of QSO absorption lines, for use in studies of abundances, relevant radiation fields, number counts as a function of redshift, and other matters, including the evolution of these parameters. The catalogue includes intervening, associated, and BAL absorbers, in order to allow a clearer definition of the relationships between these three classes. We describe the motivation for and the data products of the project to build the SDSS QSO absorption line catalogue.