We present the catalog of high Galactic-latitude (|b| > 10 • ) X-ray sources detected in the first 37-month data of Monitor of All-sky X-ray Image (MAXI) / Gas Slit Camera (GSC). To achieve the best sensitivity, we develop a background model of the GSC that well reproduces the data based on the detailed on-board calibration. Source detection is performed through image fit with the Poisson likelihood algorithm. The catalog contains 500 objects detected in the 4-10 keV band with significance of s D,4−10keV ≥ 7. The limiting sensitivity is ≈ 7.5 × 10 −12 ergs cm −2 s −1 (≈ 0.6 mCrab) in the 4-10 keV band for 50% of the survey area, which is the highest ever achieved as an all-sky survey mission covering this energy band. We summarize the statistical properties of the catalog and results from cross matching with the Swift/BAT 70-month catalog, the metacatalog of X-ray detected clusters of galaxies, and the MAXI/GSC 7-month catalog. Our catalog lists the source name (2MAXI), position and its error, detection significances and fluxes in the 4-10 keV and 3-4 keV bands, their hardness ratio, and basic information of the likely counterpart available for 296 sources.
The catalytic center of photosynthetic water oxidation, the Mn4CaO5 cluster, is assembled in photosystem II (PSII) through a light-driven process called photoactivation, whose mechanism remains elusive. Here, we used rapid-scan time-resolved Fourier transform infrared (FTIR) spectroscopy combined with the attenuated total reflection (ATR) technique to monitor the photoactivation process. Rapid-scan ATR-FTIR spectra of apo-PSII with Mn2+ upon flash illumination showed spectral features typical of carboxylate stretching vibrations, which were attributed to two carboxylate ligands, D1-D170 and D1-E189, by quantum chemical calculations. The FTIR signal decayed with a time constant of ∼0.7 s, showing that the subsequent “dark rearrangement” step occurred with a low quantum yield and Mn3+ ions were mostly released during this decay. Simulation of the kinetic process provided a slow intrinsic rate of the dark rearrangement, which was attributed to a large protein conformational change. The photoassembly mechanism of the Mn4CaO5 cluster is proposed based on these findings.
In the photosynthetic membrane of purple bacteria networks of light-harvesting 2 (LH2) complexes capture the sunlight and transfer the excitation energy. In order to investigate the mutual relationship between the supramolecular organization of the pigment-protein complexes and their biological function, the LH2 complexes were reconstituted into three types of phospholipid membranes, consisting of L-α-phosphatidylglycerol (PG), L-α-phosphatidylcholine (PC), and L-α-phosphatidylethanolamine (PE)/PG/cardiolipin (CL). Atomic force microscopy (AFM) revealed that the type of phospholipids had a crucial influence on the clustering tendency of the LH2 complexes increased from PG over PC to PE/PG/CL, where the LH2 complexes formed large, densely packed clusters. Time-resolved spectroscopy uncovered a strong quenching of the LH2 fluorescence that is ascribed to singlet-singlet and singlet-triplet annihilation by an efficient energy transfer between the LH2 complexes in the artificial membrane systems. Quantitative analysis reveals that the intercomplex energy transfer efficiency varies strongly as a function of the morphology of the nanostructure, namely in the order PE/PG/CL > PC > PG, which is in line with the clustering tendency of LH2 observed by AFM. These results suggest a strong influence of the phospholipids on the self-assembly of LH2 complexes into networks and concomitantly on the intercomplex energy transfer efficiency.
We study the three-dimensional bosonic t-J model, that is, the t-J model of "bosonic electrons" at finite temperatures. This model describes a system of an isotropic antiferromagnet with doped bosonic holes and is closely related to systems of two-component bosons in an optical lattice. The bosonic "electron" operator B xσ at the site x with a two-component spin σ (=1,2) is treated as a hard-core boson operator and represented by a composite of two slave particles: a spinon described by a Schwinger boson (CP 1 boson) z xσ and a holon described by a hard-core-boson field φ x as B xσ = φ † x z xσ . By means of Monte Carlo simulations of this bosonic t-J model, we study its phase structure and the possible phenomena like appearance of antiferromagnetic long-range order, Bose-Einstein condensation, phase separation, etc. Obtained results show that the bosonic t-J model has a phase diagram that suggests some interesting implications for high-temperature superconducting materials.
In this paper, the failsafe performance of front-andrear-wheel-independent-drive-type electric vehicles (FRID EVs) is clarified from a practical viewpoint through vehicle dynamics analysis under various road conditions and experiments on a running test course. Dynamic analyses at the time of failure were performed under severe road conditions by comparing the vehicle trajectories of FRID EVs with those of conventional EVs, i.e., two-and four-wheel motor drive-type EVs. The analyzed results show that after failure, FRID EVs continue to run safely and stably; all of the conventional EVs deviate from the travel lane in less than 2 s, which is not sufficient time for an ordinary driver to steer the vehicle to safety after being notified about vehicle failure. Using a prototype FRID EV with practical specifications, failsafe performance at the time of failure was evaluated on test courses, including roads having an ultra-low friction coefficient (µ). The experimental results showed that even if failure occurred while cornering and when running on low-µ roads, the FRID EV continued to run stably. These results proved that FRID EVs could ensure safety at the time of failure under practical running conditions. Index Terms-Body slip, electric vehicle (EV), failsafe performance, front-and-rear-wheel-independent-drive-type EV (FRID EV), fuel cell electric vehicle (FCEV), low-friction-coefficient road (low-µ road), vehicle dynamics, vehicle failure, vehicle safety, yaw rate.
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