154 research outputs found
Evolution of Small Scale Cosmological Baryon Perturbations and Matter Transfer Functions
The evolution of small scale cosmological perturbations is carefully
re-examined. Through the interaction with photons via electrons, baryon
perturbations show interesting behavior in some physical scales. Characteristic
features of the evolution of baryon density fluctuations are discussed. In CDM
models, it is found a power-law growing phase of the small-scale baryon density
fluctuations, which is characterized by the terminal velocity, after the
diffusion (Silk) damping and before the decoupling epoch. Then, a transfer
function for total matter density fluctuations is studied by taking into
account those physical processes. An analytic transfer function is presented,
which is applicable for the entire range up to a solar mass scale in the
high universe, and it is suitable also to the high baryon fraction models.Comment: 29 pages, LaTex, Submitted to Astrophysical Journa
Stochastic Gravitational Wave Background originating from Halo Mergers
The stochastic gravitational wave background (GWB) from halo mergers is
investigated by a quasi-analytic method. The method we employ consists of two
steps. The first step is to construct a merger tree by using the Extended
Press-Schechter formalism or the Sheth & Tormen formalism, with Monte-Carlo
realizations. This merger tree provides evolution of halo masses. From -body
simulation of two-halo mergers, we can estimate the amount of gravitational
wave emission induced by the individual merger process. Therefore the second
step is to combine this gravitaional wave emission to the merger tree and
obtain the amplitude of GWB. We find for Hz, where is the energy density of the GWB. It
turns out that most of the contribution on the GWB comes from halos with masses
below and mergers at low redshift, i.e., .Comment: 5 pages, 8 figures. Accepted for publication in Physical Review
MAX 4 and MAX 5 CMB anisotropy measurement constraints on open and flat-Lambda CDM cosmogonies
We account for experimental and observational uncertainties in likelihood
analyses of cosmic microwave background (CMB) anisotropy data from the MAX 4
and MAX 5 experiments. These analyses use CMB anisotropy spectra predicted in
open and spatially-flat Lambda cold dark matter cosmogonies. Amongst the models
considered, the combined MAX data set is most consistent with the CMB
anisotropy shape in Omega_0 ~ 0.1-0.2 open models and less so with that in old
(t_0 >~ 15 - 16 Gyr, i.e., low h), high baryon density (Omega_B >~ 0.0175/h^2),
low density (Omega_0 ~ 0.2 - 0.4), flat-Lambda models. The MAX data alone do
not rule out any of the models we consider at the 2-sigma level.
Model normalizations deduced from the combined MAX data are consistent with
those drawn from the UCSB South Pole 1994 data, except for the flat bandpower
model where MAX favours a higher normalization. The combined MAX data
normalization for open models with Omega_0 ~ 0.1-0.2 is higher than the upper
2-sigma value of the DMR normalization. The combined MAX data normalization for
old (low h), high baryon density, low-density flat-Lambda models is below the
lower 2-sigma value of the DMR normalization. Open models with Omega_0 ~
0.4-0.5 are not far from the shape most favoured by the MAX data, and for these
models the MAX and DMR normalizations overlap. The MAX and DMR normalizations
also overlap for Omega_0 = 1 and some higher h, lower Omega_B, low-density
flat-Lambda models.Comment: Latex, 37 pages, uses aasms4 styl
Investigating the role of the Itoigawa-Shizuoka tectonic line towards the evolution of the Northern Fossa Magna rift basin
AbstractThe Itoigawa-Shizuoka tectonic line (ISTL) fault system is considered to have one of the highest probabilities for a major inland earthquake occurrence in the whole of Japan. It is a complex fault system with the dip directions of the local fault segments changing from north to south between an east-dipping low-angle thrust fault, a strike slip fault and a west-dipping thrust fault. The tectonic relations between the different parts of the fault system and the surrounding geological units are yet to be fully explained. This study aims to reveal the juncture of the northern and central parts of the ISTL and investigate its contribution towards the shaping of the Northern Fossa Magna rift basin. We conducted 3 deployments of 1 or 2 linear arrays of seismic stations across the central and northern ISTL regions and observed local micro-earthquakes for a period of 3 years. Each deployment recorded continuous waveform data for approximately 3 months. Using arrival times of 1193 local earthquakes, we jointly determined earthquake locations and a 3D velocity model, applying the tomography method. We were able to image the regional crustal structures from the surface to a depth of 20km with a spatial resolution of 5km. Subsequently, we used the obtained 3D velocity model to relocate the background local seismicity from 2003 to 2009. The juncture of the northern and central parts of the ISTL was well constrained by our results. The depth extension of the northern parts of the ISTL fault segments follows the bottom of the Miocene Northern Fossa Magna rift basin (NFM) and forms an east-dipping low-angle fault. In contrast, the central parts of the ISTL fault segments are estimated to lie along the eastern boundary of the Matsumoto basin forming an oblique strike slip fault (Fig. 1)
Jellyfish mucin may have potential disease-modifying effects on osteoarthritis
<p>Abstract</p> <p>Background</p> <p>We aimed to study the effects of intra-articular injection of jellyfish mucin (qniumucin) on articular cartilage degeneration in a model of osteoarthritis (OA) created in rabbit knees by resection of the anterior cruciate ligament. Qniumucin was extracted from <it>Aurelia aurita </it>(moon jellyfish) and <it>Stomolophus nomurai </it>(Nomura's jellyfish) and purified by ion exchange chromatography. The OA model used 36 knees in 18 Japanese white rabbits. Purified qniumucin extracts from <it>S. nomurai </it>or <it>A. aurita </it>were used at 1 mg/ml. Rabbits were divided into four groups: a control (C) group injected with saline; a hyaluronic acid (HA)-only group (H group); two qniumucin-only groups (M groups); and two qniumucin + HA groups (MH groups). One milligram of each solution was injected intra-articularly once a week for 5 consecutive weeks, starting from 4 weeks after surgery. Ten weeks after surgery, the articular cartilage was evaluated macroscopically and histologically.</p> <p>Results</p> <p>In the C and M groups, macroscopic cartilage defects extended to the subchondral bone medially and laterally. When the H and both MH groups were compared, only minor cartilage degeneration was observed in groups treated with qniumucin in contrast to the group without qniumucin. Histologically, densely safranin-O-stained cartilage layers were observed in the H and two MH groups, but cartilage was strongly maintained in both MH groups.</p> <p>Conclusion</p> <p>At the concentrations of qniumucin used in this study, injection together with HA inhibited articular cartilage degeneration in this model of OA.</p
ARGO CMB Anisotropy Measurement Constraints on Open and Flat-Lambda CDM Cosmogonies
We use data from the ARGO cosmic microwave background (CMB) anisotropy
experiment to constrain cosmogonies. We account for the ARGO beamwidth and
calibration uncertainties, and marginalize over the offset removed from the
data. Our derived amplitudes of the CMB anisotropy detected by the ARGO
experiment are smaller than those derived previously.
We consider open and spatially-flat-Lambda cold dark matter cosmogonies, with
clustered-mass density parameter Omega_0 in the range 0.1-1, baryonic-mass
density parameter Omega_B in the range (0.005-0.029)h^{-2}, and age of the
universe t_0 in the range (10--20) Gyr. Marginalizing over all parameters but
Omega_0, the ARGO data favors an open (spatially-flat-Lambda) model with
Omega_0= 0.23 (0.1). However, these numerical values are model dependent.
At the 2 sigma confidence level model normalizations deduced from the ARGO
data are consistent with those drawn from the UCSB South Pole 1994, MAX 4+5,
White Dish, and SuZIE data sets. The ARGO open model normalizations are also
consistent with those deduced from the DMR data. However, for most
spatially-flat-Lambda models the DMR normalizations are more than 2 sigma above
the ARGO ones.Comment: 21 pages of latex. Uses aaspp4.sty. 8 figures included. ApJ in pres
Cosmological Baryon Sound Waves Coupled with the Primeval Radiation
The fluid equations for the baryon-electron system in an expanding universe
are derived from the Boltzmann equation. The effect of the Compton interaction
is taken into account properly in order to evaluate the photon-electron
collisional term. As an application, the acoustic motions of the
baryon-electron system after recombination are investigated. The effective
adiabatic index is computed for sound waves of various wavelengths,
assuming the perturbation amplitude is small. The oscillations are found to be
dumped when changes from between 1 (for an isothermal process) to 5/3
(for an adiabatic process).Comment: 20 pages, Revtex, Accepted for publication in Phys. Rev.
The properties of bioengineered chondrocyte sheets for cartilage regeneration
<p>Abstract</p> <p>Background</p> <p>Although the clinical results of autologous chondrocyte implantation for articular cartilage defects have recently improved as a result of advanced techniques based on tissue engineering procedures, problems with cell handling and scaffold imperfections remain to be solved. A new cell-sheet technique has been developed, and is potentially able to overcome these obstacles. Chondrocyte sheets applicable to cartilage regeneration can be prepared with this cell-sheet technique using temperature-responsive culture dishes. However, for clinical application, it is necessary to evaluate the characteristics of the cells in these sheets and to identify their similarities to naive cartilage.</p> <p>Results</p> <p>The expression of SOX 9, collagen type 2, 27, integrin α10, and fibronectin genes in triple-layered chondrocyte sheets was significantly increased in comparison to those in conventional monolayer culture and in a single chondrocyte sheet, implying a nature similar to ordinary cartilage. In addition, immunohistochemistry demonstrated that collagen type II, fibronectin, and integrin α10 were present in the triple-layered chondrocyte sheets.</p> <p>Conclusion</p> <p>The results of this study indicate that these chondrocyte sheets with a consistent cartilaginous phenotype and adhesive properties may lead to a new strategy for cartilage regeneration.</p
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