Long-Wavelength Excesses in Two Highly Obscured High-Mass X-Ray Binaries: IGR J16318–4848 and GX 301–2

We present evidence for excess long-wavelength emission from two high-mass X-ray binaries, IGR J16318-4848 and GX 301-2, that show enormous obscuration (N_H ≃ 10^(23)-10^(24) cm^(-2)) in their X-ray spectra. Using archival near- and mid-infrared data, we show that the spectral energy distributions of IGR J16318-4848 and GX 301-2 are substantially higher in the mid-infrared than their expected stellar emission. We successfully fit the excesses with ~1000 K blackbodies, which suggests that they are due to warm circumstellar dust that also gives rise to the X-ray absorption. However, we need further observations to constrain the detailed properties of the excesses. This discovery highlights the importance of mid-infrared observations for understanding highly obscured X-ray binaries

Orbital-selective Mass Enhancements in Multi-band Ca2−x_{2-x}Srx_{x}RuO4_{4} Systems Analyzed by the Extended Drude Model

We investigated optical spectra of quasi-two-dimensional multi-band Ca$_{2-x}$Sr$_{x}$RuO$_{4}$ systems. The extended Drude model analysis on the ab-plane optical conductivity spectra indicates that the effective mass should be enhanced near $x=0.5$. Based on the sum rule argument, we showed that the orbital-selective Mott-gap opening for the $d_{yz/zx}$ bands, the widely investigated picture, could not be the origin of the mass enhancement. We exploited the multi-band effects in the extended Drude model analysis, and demonstrated that the intriguing heavy mass state near $x=0.5$ should come from the renormalization of the $d_{xy}$ band.Comment: 4 figure

Quasinormal Ringing for Acoustic Black Holes at Low Temperature

We investigate a condensed matter ``black hole'' analogue, taking the Gross-Pitaevskii (GP) equation as a starting point. The linearized GP equation corresponds to a wave equation on a black hole background, giving quasinormal modes under some appropriate conditions. We suggest that we can know the detailed characters and corresponding geometrical information about the acoustic black hole by observing quasinormal ringdown waves in the low temperature condensed matters.Comment: 9 pages, 3 figures, PRD accepted versio

A Low Order Theory of Arctic Sea Ice Stability

We analyze the stability of a low-order coupled sea ice and climate model and extract the essential physics governing the time scales of response as a function of greenhouse gas forcing. Under present climate conditions the stability is controlled by longwave radiation driven heat conduction. However, as greenhouse gas forcing increases and the ice cover decays, the destabilizing influence of ice-albedo feedback acts on equal footing with longwave stabilization. Both are seasonally out of phase and as the system warms towards a seasonal ice state these effects, which underlie the bifurcations between climate states, combine exhibiting a "slowing down" to extend the intrinsic relaxation time scale from ~ 2 yr to 5 yr.Comment: 5 pages, 2 figure

Trends, noise and reentrant long-term persistence in Arctic sea ice

We examine the long-term correlations and multifractal properties of daily satellite retrievals of Arctic sea ice albedo and extent, for periods of $\sim$ 23 years and 32 years respectively. The approach harnesses a recent development called Multifractal Temporally Weighted Detrended Fluctuation Analysis (MF-TWDFA), which exploits the intuition that points closer in time are more likely to be related than distant points. In both data sets we extract multiple crossover times, as characterized by generalized Hurst exponents, ranging from synoptic to decadal. The method goes beyond treatments that assume a single decay scale process, such as a first-order autoregression, which cannot be justifiably fit to these observations. Importantly, the strength of the seasonal cycle "masks" long term correlations on time scales beyond seasonal. When removing the seasonal cycle from the original record, the ice extent data exhibits white noise behavior from seasonal to bi-seasonal time scales, whereas the clear fingerprints of the short (weather) and long ($\sim$ 7 and 9 year) time scales remain, the latter associated with the recent decay in the ice cover. Therefore, long term persistence is reentrant beyond the seasonal scale and it is not possible to distinguish whether a given ice extent minimum/maximum will be followed by a minimum/maximum that is larger or smaller in magnitude.Comment: 17 pages, 7 figure

Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5dd Transition Metal Oxides Srn+1_{n+1}Irn_{n}O3n+1_{3n+1} (nn=1, 2, and ∞\infty)

We investigated the electronic structures of the 5$d$ Ruddlesden-Popper series Sr$_{n+1}$Ir$_{n}$O$_{3n+1}$ ($n$=1, 2, and $\infty$) using optical spectroscopy and first-principles calculations. As 5$d$ orbitals are spatially more extended than 3$d$ or 4$d$ orbitals, it has been widely accepted that correlation effects are minimal in 5$d$ compounds. However, we observed a bandwidth-controlled transition from a Mott insulator to a metal as we increased $n$. In addition, the artificially synthesized perovskite SrIrO$_{3}$ showed a very large mass enhancement of about 6, indicating that it was in a correlated metallic state

Measuring the efficiency of capital allocation in commercial banking

Commercial banks leverage their equity capital with demandable debt that participates in the economy's payments system. The distinctive nature of this debt generates an unusual degree of liquidity risk that can, at times, threaten the payments system. To reduce this threat, insurance protects deposits; and to reduce the moral hazard problems of the debt contract and deposit insurance, bank regulation constrains risk-taking and defines standards of capital adequacy. The inherent liquidity risk of demandable debt as well as potential regulatory penalties for poor financial performance creates the potential for costly episodes of financial distress that affects banks' employment of capital. ; The existence of financial-distress costs implies that many banks are likely to take actions, such as holding additional capital, that increase bank safety at the expense of short-run returns. While such a strategy may reduce average returns in the short run, it may maximize the market value of the bank by protecting charter value and protecting against regulatory interventions. On the other hand, some banks whose charter values are low may have an incentive to follow a higher risk strategy, one that increases average return at the expense of greater risk of financial distress and regulatory intervention. ; This paper examines how banks' employment of capital in their production plans affects their "market value" efficiency. The authors develop a market-based measure of production efficiency and implement it on a sample of publicly traded bank holding companies. Our evidence indicates that banks' efficiency and, hence, the market value of their assets are influenced by the level and allocation of capital. However, even controlling for the effect of size, we find that the influence of equity capital differs markedly between banks with higher capital-to-assets ratios and those with lower ratios. For inefficient banks with higher capital-to-assets ratios, marginal increases in capitalization and asset quality boost their market-value efficiency. For inefficient banks with lower levels of capitalization, the signs of these effects are reversed. Controlling for asset size, it appears that less capitalized banks cannot afford to mimic the investment strategy of more capitalized banks, which may be using this greater capitalization to signal their safety to financial markets.Bank capital