The Nullity of Bicyclic Signed Graphs

Let \Gamma be a signed graph and let A(\Gamma) be the adjacency matrix of \Gamma. The nullity of \Gamma is the multiplicity of eigenvalue zero in the spectrum of A(\Gamma). In this paper we characterize the signed graphs of order n with nullity n-2 or n-3, and introduce a graph transformation which preserves the nullity. As an application we determine the unbalanced bicyclic signed graphs of order n with nullity n-3 or n-4, and signed bicyclic signed graphs (including simple bicyclic graphs) of order n with nullity n-5

Daytime radiative cooling using near-black infrared emitters

Recent works have demonstrated that daytime radiative cooling under direct sunlight can be achieved using multilayer thin films designed to emit in the infrared atmospheric transparency window while reflecting visible light. Here, we demonstrate that a polymer-coated fused silica mirror, as a near-ideal blackbody in the mid-infrared and near-ideal reflector in the solar spectrum, achieves radiative cooling below ambient air temperature under direct sunlight (8.2 °C) and at night (8.4 °C). Its performance exceeds that of a multilayer thin film stack fabricated using vacuum deposition methods by nearly 3 °C. Furthermore, we estimate the cooler has an average net cooling power of about 127 Wm^(-2) during daytime at ambient temperature even considering the significant influence of external conduction and convection, more than twice that reported previously. Our work demonstrates that abundant materials and straight-forward fabrication can be used to achieve daytime radiative cooling, advancing applications such as dry cooling of thermal power plants

Liver transplantation in mainland China: the overview of CLTR 2011 annual scientific report

China Liver Transplant Registry (CLTR) is the official national liver transplant registry in Mainland China that has been authorized by the National Health and Family Planning Commission of the People's Republic of China (NHFPC) and serves for both regulatory and scientific purposes. The CLTR 2011 annual scientific reports released national statistics describing current status of liver transplant (LT) in China. This article, as an accompanying document of CLTR 2011 annual scientific report, provides an overview of scientific results for LT in China. Up to December 2011, a total number of 20,877 LT performed during 1980-2011 in 81 certified transplant centers had been reported to CLTR. Of these donated livers, 92.63% were procured from deceased donors (N=19,338) and 7.37% were from living donors (N=1,539). In March 2010, the pilot project of the new deceased organ donation was initiated. From the initiation of the pilot program to the end of 2011, there were 115 LT (0.55% of all LT) using the liver grafts from Chinese categories donors. The recipient post-transplant survival had been significantly improved over years. The median post-transplant follow-up was 14.74 months, of which the longest follow-up time was 192.47 months. The 1-year, 3-year and 5-year cumulative survival rate for all recipients was 77.97%, 65.38% and 60.53%, respectively.published_or_final_versio

Density Matrix in Quantum Mechanics and Distinctness of Ensembles Having the Same Compressed Density Matrix

We clarify different definitions of the density matrix by proposing the use of different names, the full density matrix for a single-closed quantum system, the compressed density matrix for the averaged single molecule state from an ensemble of molecules, and the reduced density matrix for a part of an entangled quantum system, respectively. We show that ensembles with the same compressed density matrix can be physically distinguished by observing fluctuations of various observables. This is in contrast to a general belief that ensembles with the same compressed density matrix are identical. Explicit expression for the fluctuation of an observable in a specified ensemble is given. We have discussed the nature of nuclear magnetic resonance quantum computing. We show that the conclusion that there is no quantum entanglement in the current nuclear magnetic resonance quantum computing experiment is based on the unjustified belief that ensembles having the same compressed density matrix are identical physically. Related issues in quantum communication are also discussed.Comment: 26 pages. To appear in Foundations of Physics, 36 (8), 200

The Origin of Separable States and Separability Criteria from Entanglement-breaking Channels

In this paper, we show that an arbitrary separable state can be the output of a certain entanglement-breaking channel corresponding exactly to the input of a maximally entangled state. A necessary and sufficient separability criterion and some sufficient separability criteria from entanglement-breaking channels are given.Comment: EBCs with trace-preserving and EBCs without trace-preserving are separately discusse

Eclipsing Binaries From the CSTAR Project at Dome A, Antarctica

The Chinese Small Telescope ARray (CSTAR) has observed an area around the Celestial South Pole at Dome A since 2008. About $20,000$ light curves in the i band were obtained lasting from March to July, 2008. The photometric precision achieves about 4 mmag at i = 7.5 and 20 mmag at i = 12 within a 30 s exposure time. These light curves are analyzed using Lomb--Scargle, Phase Dispersion Minimization, and Box Least Squares methods to search for periodic signals. False positives may appear as a variable signature caused by contaminating stars and the observation mode of CSTAR. Therefore the period and position of each variable candidate are checked to eliminate false positives. Eclipsing binaries are removed by visual inspection, frequency spectrum analysis and locally linear embedding technique. We identify 53 eclipsing binaries in the field of view of CSTAR, containing 24 detached binaries, 8 semi-detached binaries, 18 contact binaries, and 3 ellipsoidal variables. To derive the parameters of these binaries, we use the Eclipsing Binaries via Artificial Intelligence (EBAI) method. The primary and the secondary eclipse timing variations (ETVs) for semi-detached and contact systems are analyzed. Correlated primary and secondary ETVs confirmed by false alarm tests may indicate an unseen perturbing companion. Through ETV analysis, we identify two triple systems (CSTAR J084612.64-883342.9 and CSTAR J220502.55-895206.7). The orbital parameters of the third body in CSTAR J220502.55-895206.7 are derived using a simple dynamical model.Comment: 41 pages, 12 figures; published online in ApJ