Cosmology with x-matter

Motivated by the possibility of $H_0t_0 > 1$ where $H_0$ and $t_0$ are the Hubble parameter and the age of the universe, respectively, we investigate the cosmology including x-matter. x-matter is expressed by the equation of state $p_x=w_0\rho_{x0} + c_s^2(\rho_x-\rho_{x0})$, where $p_x$, $\rho_x$ and $\rho_{x0}$ are the pressure, the density of x-matter and the density at present, respectively. $w_0$ and $c_s^2$ are functions of $\rho_x$ in general. x-matter has the most general form of the equation of state which is characterized by 1)violation of strong energy condition at present for $w_0 < -1/3$ ; 2) locally stable (i.e. $c_s^2\geq 0$); 3)causality is guaranteed ($c_s\leq 1$). Considering the case that $w_0$ and $c_s^2$ are constants, we find that there is a large parameter space of $(w_0,c_s^2,\Omega_{x0})$ in which the model universe is consistent with the age of the universe and the observations of distant Type I supernovae.Comment: minor changes, 4 pages, 6 figures, accepted for publication as a Letter in MNRA

Observational tests of x-matter models

We study gravitational lensing statistics, matter power spectra and the angular power spectra of the cosmic microwave background (CMB) radiation in x-matter models. We adopt an equation-of-state of x-matter which can express a wide range of matter from the pressureless dust to the cosmological constant. A new ingredient in this model is the sound speed of the x-component in addition to the equation-of-state $w_0=p_{x0}/\rho_{x0}$. Except for the cosmological constant case, the perturbations of x-matter itself are considered. Our primary interest is in the effect of non-zero sound speed on the structure formation and the CMB spectra. It is found that there exist parameter ranges where x-matter models are consistent with all current observations. The x-matter generally leaves imprints in the CMB anisotropy and the matter power spectrum, which should be detectable in future observations.Comment: minor changes, 10 pages+14 figures, MNRAS in pres

Microwave Background Anisotropies in Primeval Isocurvature Baryon Models: Constraints on the Cosmological Parameters

We have performed the most comprehensive predictions of the temperature fluctuations \dtt in the primeval isocurvature baryon models to see whether or not the models are consistent with the recent data on the cosmic microwave background anisotropies. More specifically, we computed the \dtt corresponding to the experimental set-up by the South-Pole and the Owens Valley experiments as well as the COBE satellite. The amplitudes of the predicted \dtt are normalized by means of the COBE 10$^\circ$ data. The resulting constraints on the models are presented on $n - \Omega_b$ plane in the case of $\lambda_0=1-\Omega_b$ (flat models) and $\lambda_0=0$ (open models), where $n$ is the primordial spectral index of entropy fluctuations and $\Omega_b$ is the present baryon density parameter. Our results imply that the PIB models cannot be reconciled with the current observations for any reasonable set of cosmological parameters.Comment: 10pages and 4figures compressed uuencoded postscript (with figures), UTAP-93-16

Diffusion behavior of delta-doped Si in InAlAs/InP heterostructures

Diffusion behavior of delta-doped Si in InAlAs and InP was studied by using secondary ion mass spectroscopy. A significant broadening of the profile due to postgrowth annealing was observed in In0.52Al0.48As. In contrast, the depth profile of delta-doped Si in InP was scarcely changed by annealing. This indicates that the diffusion coefficient of delta-doped Si in InP is much smaller than that in In0.52Al0.48As. Suppression of Si diffusion by using a delta-doped InP layer as the carrier supply layer (CSL) improves the thermal stability of the InP-HEMT structures

Development and Social Implementation of Smartphone App Nige-Tore for Improving Tsunami Evacuation Drills: Synergistic Effects Between Commitment and Contingency

This research explored how we can improve tsunami evacuation behavior, which has been a major social issue since the 2011 Great East Japan Earthquake and Tsunami. We introduce Nige-Tore, a smartphone app for supporting tsunami evacuation drills, which was developed within an interdisciplinary research framework. Nige-Tore serves as an effective interface tool that successfully visualizes the dynamic interactions between human actions (evacuation behavior) and natural phenomena (tsunami behavior). Drill participants can check, on their smartphone, the estimated inundation area of the approaching tsunami, along with their own current evacuation trajectory. The results of real-world trials using Nige-Tore show that the app is more powerful than conventional devices and methods that have been used in tsunami evacuation training, such as hazard maps and traditional drills that do not make use of any apps, because Nige-Tore provides an interface that enables commitment and contingency thinking—which at first glance appear to represent different orientations—to not only coexist but to synergize. “Commitment” (devotion or involvement) refers to the act of immersing oneself in and viewing as absolute one particular scenario or its potential to be actualized, given conditions in which infinite scenarios may be actualized, depending on the interactions between human systems and natural systems. “Contingency” thinking (an accidental or incidental state) refers to the act of relativizing and separating oneself from any particular scenario or its potential to be actualized, given the same conditions. The synergistic effect of “commitment” and “contingency” thinking also expands people’s capacity to cope with unexpected and unforeseen events