We present the first in-depth analysis of the massive cluster AS1063. This is one of the hottest X-ray clusters discovered to date and is undergoing a major merging event. The average temperature of the hot intracluster medium has been measured, using Chandra/ACIS-I, and found to be >11.5 keV. Optical spectroscopy, from GMOS-S, has provided a mean redshift of 0.3461 and a large velocity dispersion of 1840 +230 −150 km s −1 . Both the large velocity dispersion and high X-ray temperature suggest a very massive cluster (M 200 > 2.5 × 10 15 M ) and/or a merger system. The merger model is supported by a small offset between the galaxy density and the peak of the X-ray emission, the presence of offset and twisted X-ray isophotes, and a non-Gaussian galaxy velocity distribution. We also report that the velocity distribution is better represented by the velocity dispersion produced during a merger than by the velocity distribution of a relaxed cluster. Moreover, we find that two non-concentric beta models are a better description for the distribution of the cluster gas than a single beta model. Therefore, we propose that a recent merger event close to the plane of the sky is responsible for the observed properties of the cluster. In addition, optical imaging, from SuSI2 on the New Technology Telescope and GMOS-S at Gemini, has also uncovered the presence of several gravitational arcs that have been used to further constrain the mass and dynamics of the cluster.
We report the observation of narrow resonances in the absorption of mm wavelength radiation (30 to 50 GHz) in the vortex state of BiqSr2CaCuz08+s. When the applied field B ((~c) is swept at fixed frequency co, the absorption displays two distinct Lorentzian peaks at the resonance fields Bo and Bl . The resonance frequency decreases with increasing field, consistent with anticyclotronic behavior.At fixed cu, Bp and BI also vary strongly with temperature T. Bo and Bl increase to a sharp maximum when T crosses the vortex solid-to-liquid transition line inferred from resistivity results. The coupling of cyclotron resonance with collective modes giving rise to an anticyclotronic mode is discussed.The direct observation of electronic absorption resonances (such as cyclotron absorption) in type II superconductors should provide a valuable way to probe properties of the vortex state. Such experiments are not feasible in low T, type -II superconductors because materials with large upper critical fields H, 2 (e.g., A15's)
The catalytic properties of pulsed and resting cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1.), expressed in terms of a minimal kinetic scheme and simulated by numerical computations, were successfully described. A two-state model, in which the relative amounts of the enzyme present in each conformation are regulated by the rates ofelectron flux and 0°binding on one side and the interconversion rates on the other, accounts for the activation of cytochrome c oxidase during turnover.
Orthophotos (or orthoimages if in digital form) have long been recognised as a supplement or alternative to standard maps. The increasing applications of orthoimages require efforts to ensure the accuracy of produced orthoimages. As digital photogrammetry technology has reached a stage of relative maturity and stability, the availability of high quality ground control points (GCPs) and digital elevation models (DEMs) becomes the central issue for successfully implementing an image orthorectification project. Concerns with the impacts of the quality of GCPs and DEMs on the quality of orthoimages inspire researchers to look for more reliable approaches to acquire high quality GCPs and DEMs for orthorectification. Light Detection and Ranging (LiDAR), an emerging technology, offers capability of capturing high density three dimensional points and generating high accuracy DEMs in a fast and cost-effective way. Nowadays, highly developed computer technologies enable rapid processing of huge volumes of LiDAR data. This leads to a great potential to use LiDAR data to get high quality GCPs and DEMs to improve the accuracy of orthoimages. This paper presents methods for utilizing LiDAR intensity images to collect high accuracy ground coordinates of GCPs and for utilizing LiDAR data to generate a high quality DEM for digital photogrammetry and orthorectification processes. A comparative analysis is also presented to assess the performance of proposed methods. The results demonstrated the feasibility of using LiDAR intensity image-based GCPs and the LiDAR-derived DEM to produce high quality orthoimages.
The heme undecapeptide of cytochrome c has been converted to a bis(N-acetylated) derivative by reaction with acetic anhydride. The structure of the product has been confirmed by liquid secondary-ion mass spectrometry. As anticipated, the N-acetylated molecule exhibits much less tendency to aggregate in aqueous solution than its heme undecapeptide precursor. Around neutral pH, one axial ligand on the heme iron is provided by the same histidine residue as in the native cytochrome. The other axial ligand can be varied by the addition of exogenous donor species to produce a range of hemoprotein model compounds exhibiting mixed axial ligation. Contrary to the findings of Othman et al. [Biochemistry 1994, 33, 15437-15448] concerning heme octapeptide, the N-acetylated undecapeptide showed no tendency to bind more than one exogenous ligand per heme. At concentrations approaching millimolar and in the absence of exogenous ligands, the N-acetylated molecule may either be monodispersed, exhibiting a characteristic high-spin (S = (5)/(2)) ferric heme electron paramagnetic resonance (EPR) signal, or exist in an EPR-silent and presumably aggregated form. Interestingly, the system displays a novel dependence on the buffer with regard to which of these two forms is present in a given sample. There is no evidence in any of the spectra for the existence of an intermediate-spin (S = (3)/(2)) ferric heme as suggested by Wang and Van Wart [J. Phys. Chem. 1989, 93, 7925-7931] to be present in aqueous solutions of N-acetylated heme octapeptide. Also, in contrast to another earlier report concerning the underivatized undecapeptide [Clore et al. Inorg. Chim. Acta 1981, 56, 143-148], the N-acetylated molecule showed no evidence of catalase activity. In fact, the heme chromophore was surprisingly unstable in the presence of hydrogen peroxide.
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