The generalized second law of thermodynamics and cosmological decoherence

We pointed out that the generalized second law of thermodynamics on a de Sitter universe whose energy density stochastically fluctuates due to quantum fluctuations is seemingly violated. We have shown that even in such a case, the generalized second law is unviolated by taking cosmological decoherence into account. It has been well known that the decoherence is necessary to give a reasonable reason why our universe looks classical. Our proposal can support the importance of decoherence from another aspect, i.e. the generalized second law of thermodynamics.Comment: 5 pages, 2 figures; v2: minor corrections, references added, accepted for publication in PR

<原著>肝右葉切除における短肝静脈, 右肝静脈処理のための前方アプローチ

A simple procedure of right hepatic lobectomy for bulky liver tumors is proposed. The procedure is named "Anterior approach", which is characterized by transection of hepatic parenchyma without mobilization and rotation of the right hepatic lobe. The transection directly reaches the ventral surface of the retrohepatic inferior vena cava first at the portion of caudate process. The hepatic parenchymal transection proceeds from ventral to dorsal and from caudal to cranial. Several dorsal short hepatic veins are severed on the ventral surface of the IVC and the right hepatic vein is finally severed from inside. This method enables the minimization of operative stress and is especially useful for cases with a huge tumor in the right hepatic lobe which invades the diaphragm or thoraco-abdominal wall.巨大肝腫瘍に対する合理的な肝右葉切除法としての前方アプローチを紹介する. 肝右葉切除の標準手技として, 右葉の授動と脱転がある. これは肝の右側から, 肝部下大静脈に注ぐ短肝静脈や右肝静脈の剥離と切離を行う方法であるが, 後区域や右葉全体を占める巨大肝腫瘍の場合には, それらの手技は困難なことが多く, また腫瘍の破裂をきたす恐れもあり危険を伴う. 前方アプローチは, 右葉の脱転を行わずに直接肝実質を切離して, 肝部下大静脈腹側面に到達し, 尾状葉突起から頭側に向かつて肝実質の離断を進める方法である. 肝部下大静脈腹側面に注ぐ短肝静脈を, 順次肝離断面側から剥離処理し, 最後に右肝静脈の離断も同様に行う. 横隔膜浸潤, 胸壁, 腹壁浸潤がある場合には, 肝切離が終了してから合併切除として最後に行う. また本法は, 脱転による残存肝の阻血, 門脈血液鬱滞を回避出来る利点があり, 肝ミトコンドリアの酸化還元状態を反映する動脈血中ケトン体比(AKBR)の術中低下も軽微であることが判明しており, 手術侵襲の点からみても有用である前方アプローチの良い適応は, 1)後区域, 又は右葉全体を占拠するような巨大肝腫瘍の場合, 2)腫蕩が右横隔膜, 胸壁, 腹壁に浸潤している場合, 3)右葉の腫瘍の下大静脈への浸潤が疑われ, 下大静脈合併切除の要否を判定する場合, 4)肝障害のために右葉切除を行うには機能的予備力の点で不安がある場合, などである

Thermal Ringdown of a Kerr Black Hole: Overtone Excitation, Fermi-Dirac Statistics and Greybody Factor

We find a significant destructive interference among Kerr overtones in the early ringdown induced by an extreme mass-ratio merger of a massive black hole and a compact object, and that the ringdown spectrum apparently follows the Fermi-Dirac distribution. We numerically compute the spectral amplitude of gravitational waves induced by a particle plunging into a Kerr black hole and study the excitation of multiple quasi-normal (QN) modes. We find that the start time of ringdown is before the strain peak of the signal and corresponds to the time when the particle passes the photon sphere. When the black hole has the near-extremal rotation, the Kerr QN frequencies are close to the fermionic Matsubara frequencies with the Hawking temperature and the chemical potential of the superradiant frequency. We indeed find that the absolute square of the spectral amplitude apparently follows the Fermi-Dirac distribution with the chemical potential of around the real QN frequency of the fundamental mode. Fitting the Boltzmann distribution to the data in higher frequencies, the best-fit temperature is found out to be close to the Hawking temperature, especially for rapid rotations. In the near-extremal limit, the gravitational-wave spectrum exhibits a would-be Fermi degeneracy with the Fermi surface at the superradiant frequency $\omega = \mu_{\rm H}$. We show that the greybody factor, i.e., the absorption cross section of a black hole, leads to the Fermi-Dirac distribution. As the greybody factor is another no-hair quantity of black holes, this opens a new possibility that we can test general relativity by observationally searching for the Boltzmann distribution in $\omega \gtrsim \mu_{\rm H}$ without extracting QN modes from ringdown. We could measure the mass and angular momentum of ringing black holes and could probe the Kerr/CFT by measuring the greybody factor imprinted on the ringdown spectrum.Comment: 19 pages, 13 figure