We present a three-dimensional simulation of the dynamic emergence of a twisted magnetic flux tube from the top layer of the solar convection zone into the solar atmosphere and corona. It is found ...that after a brief initial stage of flux emergence during which the two polarities of the bipolar region become separated and the tubes intersecting the photosphere become vertical, significant rotational motion sets in within each polarity. The rotational motions of the two polarities are found to twist up the inner field lines of the emerged fields such that they change their orientation into an inverse configuration (i.e., pointing from the negative polarity to the positive polarity over the neutral line). As a result, a flux rope with sigmoid-shaped, dipped core fields forms in the corona, and the center of the flux rope rises in the corona with increasing velocity as the twisting of the flux rope footpoints continues. The rotational motion in the two polarities is a result of propagation of nonlinear torsional Alfven waves along the flux tube, which transports significant twist from the tube's interior portion toward its expanded coronal portion. This is a basic process whereby twisted flux ropes are developed in the corona with increasing twist and magnetic energy, leading up to solar eruptions.
We present three-dimensional MHD simulations of the evolution of the magnetic field in the corona where the emergence of a twisted magnetic flux tube is driven at the lower boundary into a ...pre-existing coronal potential arcade field. Through a sequence of simulations in which we vary the amount of twisted flux transported into the corona before the emergence is stopped, we investigate the conditions that lead to a dynamic eruption of the resulting coronal flux rope. It is found that the critical condition for the onset of eruption is for the center of the flux rope to reach a critical height at which the corresponding potential field declines with height at a sufficiently steep rate, consistent with the onset of the torus instability of the flux rope. In some cases, immediately after the emergence is stopped, the coronal flux rope first settles into a quasi-static rise with an underlying sigmoid-shaped current layer developing. Preferential heating of field lines going through this current layer may give rise to the observed quiescent X-ray sigmoid loops before eruption. Reconnections in the current layer during the initial quasi-static stage is found to add detached flux to the coronal flux rope, allowing it to rise quasi-statically to the critical height and dynamic eruption of the flux rope then ensues. By identifying field lines whose tops are in the most intense part of the current layer during the eruption, we deduce the evolution and morphology of the post-flare X-ray loops and the flare ribbons at their footpoints.
Acute lung injury (ALI) and its severe form, known as acute respiratory distress syndrome (ARDS), are caused by direct pulmonary insults and indirect systemic inflammatory responses that result from ...conditions such as sepsis, trauma, and major surgery. The reciprocal influences between pulmonary and systemic inflammation augments the inflammatory process in the lung and promotes the development of ALI. Emerging evidence has revealed that alveolar macrophage (AM) death plays important roles in the progression of lung inflammation through its influence on other immune cell populations in the lung. Cell death and tissue inflammation form a positive feedback cycle, ultimately leading to exaggerated inflammation and development of disease. Pharmacological manipulation of AM death signals may serve as a logical therapeutic strategy for ALI/ARDS. This review will focus on recent advances in the regulation and underlying mechanisms of AM death as well as the influence of AM death on the development of ALI.
Background
IL‐25 has been proposed to play a key role in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). This study aimed to evaluate the association of IL‐25 with the ...Th2‐biased inflammatory profiles in CRSwNP.
Methods
Nasal polyp (NP) tissues and control uncinate process tissues were collected from 92 patients with CRSwNP, 20 patients with chronic rhinosinusitis without nasal polyps (CRSsNP), and 16 normal control subjects. IL‐25 expression was examined using immunohistochemistry and immunofluorescence staining, flow cytometry, RT‐qPCR, and ELISA. The inflammatory profiles and clinical characteristics of 2 NP subtypes (IL‐25high and IL‐25low) were evaluated, and the effects of IL‐25 on Th2 cytokine production in cultured dispersed polyp cells were examined in vitro.
Results
The mRNA and protein levels of IL‐25 were significantly increased in the polyp tissues compared with the control uncinate process tissues. The IL‐25high subtype showed greater computed tomography scores, endoscopic scores, and Th2 response. Exposure to IL‐25 activated type 2 innate lymphoid cells and Th2 cells in NP simultaneously which further increased Th2 cytokine production in vitro.
Conclusions
Local IL‐25 plays a crucial role in promoting Th2‐biased inflammatory profiles in NP and may serve as a promising therapeutic target in CRSwNP patients.
Global Patterns of Groundwater Table Depth Fan, Y.; Li, H.; Miguez-Macho, G.
Science (American Association for the Advancement of Science),
02/2013, Letnik:
339, Številka:
6122
Journal Article
Recenzirano
Shallow groundwater affects terrestrial ecosystems by sustaining river base-flow and root-zone soil water in the absence of rain, but little is known about the global patterns of water table depth ...and where it provides vital support for land ecosystems. We present global observations of water table depth compiled from government archives and literature, and fill in data gaps and infer patterns and processes using a groundwater model forced by modern climate, terrain, and sea level. Patterns in water table depth explain patterns in wetlands at the global scale and vegetation gradients at regional and local scales. Overall, shallow groundwater influences 22 to 32% of global land area, including ∼15% as groundwater-fed surface water features and 7 to 17% with the water table or its capillary fringe within plant rooting depths.
The room‐temperature synthesis of a new two‐dimensional (2D) zirconium‐containing carbide, Zr3C2Tz MXene is presented. In contrast to traditional preparation of MXene, the layered ternary Zr3Al3C5 ...material instead of MAX phases is used as source under hydrofluoric acid treatment. The structural, mechanical, and electronic properties of the synthesized 2D carbide are investigated, combined with first‐principles density functional calculations. A comparative study on the structrual stability of our obtained 2D Zr3C2Tz and Ti3C2Tz MXenes at elevated temperatures is performed. The obtained 2D Zr3C2Tz exhibits relatively better ability to maintain 2D nature and strucural integrity compared to Ti‐based Mxene. The difference in structural stability under high temperature condition is explained by a theoretical investigation on binding energy.
Zr3C2Tz nanosheets: A 2D zirconium‐containing carbide, Zr3C2Tz MXene, is obtained by selective etching of Al3C3 units from layered ternary Zr3Al3C5 beyond MAX phases (see picture) at room temperature. The structural, mechanical, and electronic properties of the 2D carbide were investigated combined with density functional calculations. The 2D Zr3C2Tz exhibits excellent thermal stability, which exists even at 1200 °C in vacuum.
Summary
This meta-analysis revealed that diabetic adults had a twofold greater risk of hip fractures compared with non-diabetic populations, and this association was more pronounced in type 1 ...diabetes.
Introduction
The relationship between diabetes mellitus and risk of hip fracture yielded conflicting results. We conducted a meta-analysis to investigate the association between diabetes mellitus and the risk of hip fractures based on observational studies.
Methods
We conducted a systematic literature search of PubMed and Embase databases through May 2015. We selected cohort and case–control studies providing at least age-adjusted risk ratio (RR) and corresponding 95 % confidence intervals (CI) of hip fractures among diabetic and non-diabetic subjects. Moreover, we pooled the female-to-male RR of hip fractures from studies that reported gender-specific risk estimate in a single study.
Results
Twenty-one studies involving 82,293 hip fracture events among 6,995,272 participants were identified. Diabetes mellitus was associated with an increased risk of hip fractures (RR 2.07; 95 % CI 1.83–2.33) in a random effects model. Subgroup analysis indicated that excess risk of hip fracture was more pronounced in type 1 diabetes (RR 5.76; 95 % CI 3.66–9.07) than that in type 2 diabetes (RR 1.34; 95 % CI 1.19–1.51). The pooled female-to-male RR of hip fractures was 1.09 (95 % CI 0.93–1.28).
Conclusions
Individuals with diabetes mellitus have an excessive risk of hip fractures, and this relationship is more pronounced in type 1 diabetes. The association between diabetes and hip fracture risk is similar in men and women.
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