Recurrent Outbursts and Jet Ejections Expected in Swift J1644+57: Limit-Cycle Activities in a Supermassive Black Hole

The tidal disruption event by a supermassive black hole in Swift J1644+57 can trigger limit-cycle oscillations between a supercritically accreting X-ray bright state and a subcritically accreting X-ray dim state. Time evolution of the debris gas around a black hole with mass M=10^{6} {\MO} is studied by performing axisymmetric, two-dimensional radiation hydrodynamic simulations. We assumed the $\alpha$-prescription of viscosity, in which the viscous stress is proportional to the total pressure. The mass supply rate from the outer boundary is assumed to be ${\dot M}_{\rm supply}=100L_{\rm Edd}/c^2$, where $L_{\rm Edd}$ is the Eddington luminosity, and $c$ is the light speed. Since the mass accretion rate decreases inward by outflows driven by radiation pressure, the state transition from a supercritically accreting slim disk state to a subcritically accreting Shakura-Sunyaev disk starts from the inner disk and propagates outward in a timescale of a day. The sudden drop of the X-ray flux observed in Swift J1644+57 in August 2012 can be explained by this transition. As long as ${\dot M}_{\rm supply}$ exceeds the threshold for the existence of a radiation pressure dominant disk, accumulation of the accreting gas in the subcritically accreting region triggers the transition from a gas pressure dominant Shakura-Sunyaev disk to a slim disk. This transition takes place at $t {\sim}~50/({\alpha}/0.1)$ days after the X-ray darkening. We expect that if $\alpha > 0.01$, X-ray emission with luminosity $\gtrsim 10^{44}$ ${\rm erg}{\cdot}{\rm s}^{-1}$ and jet ejection will revive in Swift J1644+57 in 2013--2014.Comment: 6 pages, 4 figures, accepted for publication in PASJ Letter

Experimental Model of Asthma by Toluene Diisocyanate (TDI)

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Attention has been paid to respiratory hypersensitivity in workers who are exposed to toluene diisocyanate (TDI) in their workshops. An experimental model of asthma in guinea pigs by TDI has been developed. A 10% TDI solution dissolved in ethyl acetate was painted on the nasal cavities of guinea pigs with a thin cotton applicator once daily for five consecutive days. Three weeks later, the animals were challenged with a 5% TDI solution. Exertional breathing accompanied by the prolongation of expiratory phase was observed among the test animals. The number of the animals suffering from the attacks increased by the repetitive provocations. Although some of the guinea pigs suffered from anaphylaxis by the provocation procedures, the attacks including the anaphylactic shocks hardly brought about deaths in the animals. It was found that passive transfer of the symtom was possible in our experimental system. Both eosinophilic infiltration in the lung and eosinophilia in the peripheral bood were found among the test animals. This experimental model was developed by the appliaction of a simple chemical alone to the respiratory tract of guinea pigs. A significance of the model is discussed with the review of the literatures concerned

Concept of Virtual Incision for Minimally Invasive Surgery

Minimally invasive surgery has been introduced to various surgical fields for its benefits such as smaller scars and less pain as compared to open surgery. Highly skilled surgical techniques are required for surgeons to conduct minimally invasive surgery with fewer ports, whereas minimally invasive surgery has a number of advantages for patients. Single-incision laparoscopic surgery (SILS), in which surgical instruments and a laparoscope are inserted through a single port, has better cosmetic results than conventional multi-incision surgery; moreover, the scar is invisible when the port is opened in navel. However, instrument collisions and visual defects often occur due to the limited space of the single opening. We propose a new surgical approach entitled “virtual incision” that enables surgeons to increase the number of openings virtually. Using our approach, we have developed two types of master-slave surgical robot systems for SILS—remote-operated and local-operated systems—which have operability close to that of multiple-incision surgery. Through evaluation of these systems, we demonstrated that the visual field and operability during virtual incision surgery are similar to those of conventional multi-incision surgery. Our surgical approach can be applied to not only single-incision surgery but also multi-incision surgery, and is very likely to improve operability

Background-metric Independent Formulation of 4D Quantum Gravity

Using the background-metric independence for the traceless mode as well as the conformal mode, 4D quantum gravity is described as a quantum field theory defined on a non-dynamical background-metric. The measure then induces an action with 4 derivatives. So we think that 4-th order gravity is essential and the Einstein-Hilbert term should be treated like a mass term. We introduce the dimensionless self-coupling constant t for the traceless mode. In this paper we study a model where the measure can be evaluated in the limit $t \to 0$ exactly, using the background-metric independence for the conformal mode. The t-dependence of the measure is determined perturbatively using the background-metric independence for the traceless mode.Comment: 27 pages, references added, some sentences added and corrected especially in sect.3 and 6; version to appear in Nucl. Phys.

Momentum transfer in non-equilibrium steady states

When a Brownian object interacts with non-interacting gas particles under non-equilibrium conditions, the energy dissipation associated to the Brownian motion causes an additional force on the object as a `momentum transfer deficit'. This principle is demonstrated first by a new NESS model and then applied to several known models such as adiabatic piston for which simple explanation has been lacking.Comment: 4 pages, 3 figure