Quasinormal Modes of Dirty Black Holes

Quasinormal mode (QNM) gravitational radiation from black holes is expected to be observed in a few years. A perturbative formula is derived for the shifts in both the real and the imaginary part of the QNM frequencies away from those of an idealized isolated black hole. The formulation provides a tool for understanding how the astrophysical environment surrounding a black hole, e.g., a massive accretion disk, affects the QNM spectrum of gravitational waves. We show, in a simple model, that the perturbed QNM spectrum can have interesting features.Comment: 4 pages. Published in PR

Financial Crisis and the Comovements of Housing Sub-markets: Do relationships change after a crisis?

This study of the co-movements of the transaction prices and trading volumes reveal that the mean correlation of prices, and trading volumes alike, among different housing sub-markets increases during the market boom. After a financial crisis, the correlations drop dramatically and stay low. The distribution of the correlations changes from skewed to symmetric. All these coincide with the increase in the total variance of prices, as well as the share of the idiosyncratic component in the total variance after the crisis. These findings are consistent to a family of theories which emphasize on “regime switch” in expectation.financial crisis; hedonic pricing; structural break; evolution of valuation; rolling regression

Unification of bulk and interface electroresistive switching in oxide systems

We demonstrate that the physical mechanism behind electroresistive switching in oxide Schottky systems is electroformation, as in insulating oxides. Negative resistance shown by the hysteretic current-voltage curves proves that impact ionization is at the origin of the switching. Analyses of the capacitance-voltage and conductance-voltage curves through a simple model show that an atomic rearrangement is involved in the process. Switching in these systems is a bulk effect, not strictly confined at the interface but at the charge space region.Comment: 4 pages, 3 figures, accepted in PR

Perturbative Approach to the Quasinormal Modes of Dirty Black Holes

Using a recently developed perturbation theory for uasinormal modes (QNM's), we evaluate the shifts in the real and imaginary parts of the QNM frequencies due to a quasi-static perturbation of the black hole spacetime. We show the perturbed QNM spectrum of a black hole can have interesting features using a simple model based on the scalar wave equation.Comment: Published in PR

Case Report: Spinal Anesthesia by Mini-laminotomy for a Patient with Ankylosing Spondylitis who was Difficult to Anesthetize

Case reportBackground: Orthopaedic surgeons frequently encounter patients with ankylosing spondylitis who would benefit from various types of lower limb operations; however, some of these patients present challenges for anesthesiologists. Case Description: We report the case of a 65-year-old patient with a fractured femoral component 30 years after a cemented THA. The patient had severe tracheal stenosis and ankylosing spondylitis making general endotracheal and conventional neuraxial anesthesia nearly impossible. Literature Review: Possible alternative anesthetic approaches described in the literature include awake fiberoptic bronchoscopic guided intubation, laryngeal mask airway, and caudal anesthesia. Purposes and Clinical Relevance: We achieved successful anesthesia using spinal laminotomy with the patient under local anesthesia followed by insertion of a spinal catheter and injection of an anesthetic agent. The loosened component was revised to a cementless THA. © 2010 The Author(s).published_or_final_versionSpringer Open Choice, 31 May 201

Droplets in the coexistence region of the two-dimensional Ising model

The two-dimensional Ising model with fixed magnetization is studied using Monte Carlo techniques. At the coexistence line, the macroscopic, extensive droplet of minority spins becomes thermally unstable by breaking up into microscopic clusters. Intriguing finite--size effects as well as singularities of thermal and cluster properties associated with the transition are discussed.Comment: 7 pages, 3 figures included, submitted to J. Phys. A: Math. Ge

Cholangiographic Features in the Diagnosis and Management of Obstructive Icteric Type Hepatocellular Carcinoma

In 11 years and 3 months, 2037 patients with HCC were seen and 48 patients (2.4%) were diagnosed to have obstructive icteric type HCC. Five patients were terminally ill and were not investigated further. Forty three patients were initially investigated by endoscopic retrograde cholangiography (ERC) or percutaneous transhepatic cholangiogram (PTC) and classified as having obstructive icteric type 1, 2, or 3 HCC based on the cholangiographic findings. The obstruction in type 1 HCC was due to intraluminal tumour casts and/or tumour fragments obstructing the hepatic ductal confluence or common bile duct, while intraluminal blood clots, from haemobilia, filling the biliary tree was the cause in type 2 HCC. The pathology in type 3 HCC was extraluminal obstruction by extensive tumour encasement of the intra–hepatic biliary ductal system and/or extrinsic compression of the hepatic and common bile ducts by tumour(s) and/or malignant lymph nodes. At the initial ERC/PTC, 10 patients (5 resected, 50%) had obstructive icteric type 1 and 23 patients (0 resected) had obstructive icteric type 3 HCC. Of the 10 patients initially classified according to cholangiography to have obstructive icteric type 2 HCC, subsequent investigations revealed that 6 patients had type 1 HCC (4 resectable, 67%) and 4 patients had type 3 HCC (0 resectable). The classification of the obstructive icteric type HCC into types 1, 2, and 3, based on the initial cholangiographic appearances has simplified and rationalized our management strategy for this condition

Measurement of Cosmic-ray Muons and Muon-induced Neutrons in the Aberdeen Tunnel Underground Laboratory

We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be $I_{\mu} = (5.7 \pm 0.6) \times 10^{-6}$ cm$^{-2}$s$^{-1}$sr$^{-1}$. The yield of muon-induced neutrons in the liquid scintillator was determined to be $Y_{n} = (1.19 \pm 0.08 (stat) \pm 0.21 (syst)) \times 10^{-4}$ neutrons/($\mu\cdot$g$\cdot$cm$^{-2}$). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of $\left\langle E_{\mu} \right\rangle^{0.76 \pm 0.03}$ for liquid-scintillator targets.Comment: 14 pages, 17 figures, 3 table