A model of the solar chromosphere that consists of two fundamentally different regions, a lower region and an upper region, is proposed. The lower region is covered mostly by weak locally closed ...magnetic field and small network areas of extremely strong, locally open field. The field in the upper region is relatively uniform and locally open, connecting to the corona. The chromosphere is heated by strong collisional damping of Alfvén waves, which are driven by turbulent motions below the photosphere. The heating rate depends on the field strength, wave power from the photosphere, and altitude in the chromosphere. The waves in the internetwork area are mostly damped in the lower region, supporting radiation in the lower chromosphere. The waves in the network area, carrying more Poynting flux, are only weakly damped in the lower region. They propagate into the upper region. As the thermal pressure decreases with height, the network field expands to form the magnetic canopy where the damping of the waves from the network area supports radiation in the whole upper region. Because of the vertical stratification and horizontally nonuniform distribution of the magnetic field and heating, one circulation cell is formed in each of the upper and lower regions. The two circulation cells distort the magnetic field and reinforce the funnel-canopy-shaped magnetic geometry. The model is based on classical processes and is semi-quantitative. The estimates are constrained according to observational knowledge. No anomalous process is invoked or needed. Overall, the heating mechanism is able to damp 50% of the total wave energy.
Surrogate models are used to dramatically improve the design efficiency of numerical aerodynamic shape optimization, where high-fidelity, expensive computational fluid dynamics (CFD) is often ...employed. Traditionally, in adaptation, only one single sample point is chosen to update the surrogate model during each updating cycle, after the initial surrogate model is built. To enable the selection of multiple new samples at each updating cycle, a few parallel infilling strategies have been developed in recent years, in order to reduce the optimization wall clock time. In this article, an alternative parallel infilling strategy for surrogate-based constrained optimization is presented and demonstrated by the aerodynamic shape optimization of transonic wings. Different from existing methods in which multiple sample points are chosen by a single infill criterion, this article uses a combination of multiple infill criteria, with each criterion choosing a different sample point. Constrained drag minimizations of the ONERA-M6 and DLR-F4 wings are exercised to demonstrate the proposed method, including low-dimensional (6 design variables) and higher-dimensional problems (up to 48 design variables). The results show that, for surrogate-based optimization of transonic wings, the proposed method is more effective than the existing parallel infilling strategies, when the number of initial sample points are in the range from
N
v
to
8N
v
(
N
v
here denotes the number of design variables). Each case is repeated 50 times to eliminate the effect of randomness in our results.
This paper investigates the mechanical properties of polypropylene hybrid fiber-reinforced concrete. There are two forms of polypropylene fibers including coarse monofilament, and staple fibers. The ...content of the former is at 3kg/m3, 6kg/m3, and 9kg/m3, and the content of the latter is at 0.6kg/m3. The experimental results show that the compressive strength, splitting tensile strength, and flexural properties of the polypropylene hybrid fiber-reinforced concrete are better than the properties of single fiber-reinforced concrete. These two forms of fibers work complementarily. The staple fibers have good fineness and dispersion so they can restrain the cracks in primary stage. The monofilament fibers have high elastic modulus and stiffness. When the monofilament fiber content is high enough, it is similar to the function of steel fiber. Therefore, they can take more stress during destruction. In addition, hybrid fibers disperse throughout concrete, and they are bond with mixture well, so the polypropylene hybrid fiber-reinforced concrete can effectively decrease drying shrinkage strain.
A kidney‐paired donation (KPD) pool consists of transplant candidates and their incompatible donors, along with nondirected donors (NDDs). In a match run, exchanges are arranged among pairs in the ...pool via cycles, as well as chains created from NDDs. A problem of importance is how to arrange cycles and chains to optimize the number of transplants. We outline and examine, through example and by simulation, four schemes for selecting potential matches in a realistic model of a KPD system; proposed schemes take account of probabilities that chosen transplants may not be completed as well as allowing for contingency plans when the optimal solution fails. Using data on candidate/donor pairs and NDDs from the Alliance for Paired Donation, the simulations extend over 8 match runs, with 30 pairs and 1 NDD added between each run. Schemes that incorporate uncertainties and fallbacks into the selection process yield substantially more transplants on average, increasing the number of transplants by as much as 40% compared to a standard selection scheme. The gain depends on the degree of uncertainty in the system. The proposed approaches can be easily implemented and provide substantial advantages over current KPD matching algorithms.
This article describes four schemes for selecting exchange cycles and chains in a kidney‐paired donation program and investigates, through simulations, the advantage of taking account of uncertainty and fallback options in the planning stage. See editorial from Gentry and Segev on page 2539, and related articles from Fumo et al on page 2646 and Flechner et al on page 2712.
Background
B lymphocytes are an important cell population of the immune regulation; their role in the regulation of food allergy has not been fully understood yet.
Objective
This study aims to ...investigate the role of a subpopulation of tolerogenic B cells (TolBC) in the generation of regulatory T cells (Treg) and in the suppression of food allergy‐induced intestinal inflammation in mice.
Methods
The intestinal mucosa‐derived CD5+ CD19+ CX3CR1+ TolBCs were characterized by flow cytometry; a mouse model of intestinal T helper (Th)2 inflammation was established to assess the immune regulatory role of this subpopulation of TolBCs.
Results
A subpopulation of CD5+ CD19+ CX3CR1+ B cells was detected in the mouse intestinal mucosa. The cells also expressed transforming growth factor (TGF)‐β and carried integrin alpha v beta 6 (αvβ6). Exposure to recombinant αvβ6 and anti‐IgM antibody induced naive B cells to differentiate into the TGF‐β‐producing TolBCs. Coculturing this subpopulation of TolBCs with Th0 cells generated CD4+ CD25+ Foxp3+ Tregs. Adoptive transfer with the TolBCs markedly suppressed the food allergy‐induced intestinal Th2 pattern inflammation in mice.
Conclusions
CD5+ CD19+ CX3CR1+ TolBCs are capable of inducing Tregs in the intestine and suppress food allergy‐related Th2 pattern inflammation in mice.
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