One Amino Acid Change of Angiotensin II Diminishes Its Effects on Abdominal Aortic Aneurysm

Angiotensin (Ang) A is formed by the decarboxylation of the N terminal residue of AngII. The present study determined whether this one amino acid change impacted effects of AngII on abdominal aortic aneurysm (AAA) formation in mice. Computational analyses implicated that AngA had comparable binding affinity to both AngII type 1 and 2 receptors as AngII. To compare effects of these two octapeptides in vivo, male low-density lipoprotein receptor (Ldlr) or apolipoprotein E (Apoe) deficient mice were infused with either AngII or AngA (1 μg/kg/min) for 4 weeks. While AngII infusion induced AAA consistently in both mouse strains, the equivalent infusion rate of AngA did not lead to AAA formation. We also determined whether co-infusion of AngA would influence AngII-induced aortic aneurysm formation in male Apoe−/− mice. Co-infusion of the same infusion rate of AngII and AngA did not change AngII-induced AAA formation. Since it was reported that a 10-fold higher concentration of AngA elicited comparable vasoconstrictive responses as AngII, we compared a 10-fold higher rate (10 μg/kg/min) of AngA infusion into male Apoe−/− mice with AngII (1 μg/kg/min). This rate of AngA led to abdominal aortic dilation in three of ten mice, but no aortic rupture, whereas the 10-fold lower rate of AngII infusion led to abdominal aortic dilation or rupture in eight of ten mice. In conclusion, AngA, despite only being one amino acid different from AngII, has diminished effects on aortic aneurysmal formation, implicating that the first amino acid of AngII has important pathophysiological functions

PSR J1926-0652: A Pulsar with Interesting Emission Properties Discovered at FAST

We describe PSR J1926-0652, a pulsar recently discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive single-pulse detections from FAST and long-term timing observations from the Parkes 64-m radio telescope, we probed phenomena on both long and short time scales. The FAST observations covered a wide frequency range from 270 to 800 MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at least four profile components, short-term nulling lasting from 4 to 450 pulses, complex subpulse drifting behaviours and intermittency on scales of tens of minutes. While the average band spacing P3 is relatively constant across different bursts and components, significant variations in the separation of adjacent bands are seen, especially near the beginning and end of a burst. Band shapes and slopes are quite variable, especially for the trailing components and for the shorter bursts. We show that for each burst the last detectable pulse prior to emission ceasing has different properties compared to other pulses. These complexities pose challenges for the classic carousel-type models.Comment: 13pages with 12 figure

Industrial productivity performance in Chinese regions (1987–2002): a decomposition approach

This article investigates the productivity performance of China's industries 1987–2002, by means of a provincial panel. Productivity growth is decomposed into four components: technical progress, scale efficiezncy change, and improvements in technical and allocative efficiency. Although total factor productivity growth had been the second major contributor to industrial growth (after capital accumulation), it has been driven mainly by technical progress rather than efficiency improvement. The estimated stochastic production frontier function exhibits substantial economies of scale. Regional differences in technical progress are negligible, but differences in technical efficiency are statistically significant across regions. The restructuring of state-owned enterprises from the mid-1990s seems to have improved technical efficiency considerably, while the performance of allocative efficiency does not seem to be converging towards standard conditions for optimizing firms under perfect competition. Factor price distortions, like artificially cheap capital together with suppressed wage levels, might have been the driving forces behind China's capital-intensive industrial growth and technology-dependent productivity performance

The performance of industrial productivity across regions of China: Structural differences, institutional shocks and dynamic characteristics

This paper is dedicated to probing into the dynamic performances of industrial productivity across regions of transitional China, using the panel data of provincial level. Based on the approach by Kumbhakar (2000), TFP (total factor productivity) growth is decomposed into four components. The main results are as follows. First, since 1988, the industrial TFP growth has been commonly accelerated across regions, with a rising technical change rate as the principal impetus. Second, meanwhile, technical efficiency and factors’ allocative efficiency are deteriorated with scale efficiency switching from being retrogressive to being progressive. Third, although the SOE (state-owned enterprise) reform in the late 1990s has constituted a common shock to the industrial productivity, the eastern area with relatively few SOEs suffers the least from this policy enforcement. Fourth, by exploring the sources of productivity differences, we further confirm that the institutional shock launched by SOE reform in the late 1990s is crucial for the enhancement of scale effects as well as the temporarily rapid decline of factors’ allocative efficiency; in addition, the educational level of the labor-force and the share of non-SOEs in the industrial output contribute positively to the acceleration of technical change and the improvement of allocative efficiency. The economic transition, accompanied by gradual institutional reforms, is reshaping the map of regional industrialization through various channels

A bubble-based EMMS model for gas-solid bubbling fluidization

An EMMS/bubbling model for gas-solid bubbling fluidized bed was proposed based on the energy-minimization multi-scale (EMMS) method (Li and Kwauk, 1994). In this new model, the meso-scale structure was characterized with bubbles in place of clusters of the original EMMS method. Accordingly, the bubbling fluidized bed was resolved into the suspending and the energy-dissipation sub-systems over three sub-phases, i.e., the emulsion phase, the bubble phase and their inter-phase in-between. A stability condition of minimization of the energy consumption for suspending particles (N(5)-> min) was proposed, to close the hydrodynamic equations on these sub-phases. This bubble-based EMMS model has been validated and found in agreement with experimental data available in literature. Further, the unsteady-state version of the model was used to calculate the drag coefficient for two-fluid model (TFM). It was found that TFM simulation with EMMS/bubbling drag coefficient allows using coarser grid than that with homogeneous drag coefficient, resulting in both good predictability and scalability. (C) 2011 Elsevier Ltd. All rights reserved

A structure-dependent multi-fluid model (SFM) for heterogeneous gas-solid flow

For the heterogeneous gas solid flow in a fluidized bed, meso-scale structures, such as bubble and cluster, have significant effects on the hydrodynamics, mass/heat transfer and reaction rate. These structures can be described with certain kinds of bimodal probability density distribution of solids concentration, i.e., the dilute-dense two-phase structures. To keep the physical nature of these mesoscale structures in mathematical formulation, a structure-dependent, multi-fluid model (SFM) was proposed. Then, the SFM was reduced to the conventional two-fluid model (TFM) as well as the hydrodynamic equations of the bubble-based and cluster-based EMMS (energy-minimization multiscale) models by assuming different simplifications of structures. Thus, the SFM unifies these different models. A new version of bubble-based EMMS model was presented thereby and validated with comparison to experimental data. This bubble-based EMMS model was found to be applicable to wide flow regimes ranging from bubbling, turbulent to fast fluidization. (C) 2013 Elsevier Ltd. All rights reserved

A review of multiscale CFD for gas-solid CFB modeling

Meso-scale structure is of critical importance to circulating fluidized bed (CFB) applications. Computational fluid dynamics (CFD) with consideration of meso-scale structures can help understand the structure-oriented coupling between flow, heat/mass transfer and reactions. This article is to review our recent progress on the so-called multiscale CFD (MSCFD), which characterizes the sub-grid meso-scale structure with stability criteria in addition to conservation equations. It is found that the mesh-independent solution of fine-grid two-fluid model (TFM) without sub-grid structures is inexact, in the sense that it overestimates the drag coefficient and fails to capture the characteristic S-shaped axial profile of voidage in a CFB riser. By comparison, MSCFD approach in terms of EMMS/matrix seems to reach a mesh-independent solution of the sub-grid structure, and succeeds in predicting the axial profile and flow regime transitions. Further application of MSCFD finds that neglect of geometric factors is one of the major reasons that cause disputes in understanding the flow regime transitions in a CFB. The operating diagram should, accordingly, include geometric factors besides commonly believed operating parameters for the intrinsic flow regime diagram. Recent extension of MSCFD to mass transfer finds that Reynolds number is insufficient for correlating the overall Sherwood number in a CFB. This is believed the main reason why the conventional correlations of Sherwood number scatter by several orders of magnitude. Certain jump change of state of motion around Reynolds number of 50-100 can be expected to clarify the abrupt decay of Sherwood number in both classical- and circulating-fluidized beds. Finally, we expect that the real-size, 3-D, full-loop. time-dependent multiscale simulation of CFB is an emerging paradigm that will realize virtual experiment of CFBs. (C) 2009 Elsevier Ltd. All rights reserved