Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth's magnetosphere, where the process can be investigated in situ by spacecraft. On 11 ...July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth's magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvénic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0.1 to 0.2, consistent with fast reconnection. The well-structured multiple layers of electron populations indicate that the dominant electron dynamics are mostly laminar, despite the presence of turbulence near the reconnection site.
To determine if the association between hyperuricaemia and poor outcomes in heart failure (HF) varies by chronic kidney disease (CKD).
Of the 2645 systolic HF patients in the Beta-Blocker Evaluation ...of Survival Trial with data on baseline serum uric acid, 1422 had hyperuricaemia (uric acid ≥6 mg/dL for women and ≥8 mg/dL for men). Propensity scores for hyperuricaemia, estimated for each patient, were used to assemble a matched cohort of 630 pairs of patients with and without hyperuricaemia who were balanced on 75 baseline characteristics. Associations of hyperuricaemia with outcomes during 25 months of median follow-up were examined in all patients and in those with and without CKD (estimated glomerular filtration rate of <60 mL/min/1.73 m(2)). Hyperuricaemia-associated hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality and HF hospitalization were 1.44 (1.12-1.85, P = 0.005) and 1.27 (1.02-1.58, P = 0.031), respectively. Hazard ratios (95% CIs) for all-cause mortality among those with and without CKD were 0.96 (0.70-1.31, P = 0.792) and 1.40 (1.08-1.82, P = 0.011), respectively (P for interaction, 0.071), and those for HF hospitalization among those with and without CKD were 0.99 (0.74-1.33, P = 0.942) and 1.49 (1.19-1.86, P = 0.001), respectively (P for interaction, 0.033).
Hyperuricaemia has a significant association with poor outcomes in HF patients without CKD but not in those with CKD, suggesting that hyperuricaemia may predict poor outcomes when it is primarily a marker of increased xanthine oxidase activity, but not when it is primarily due to impaired renal excretion of uric acid.
We report in‐situ measurements by three THEMIS spacecraft showing the evolution of reconnection in a solar wind current sheet as the current sheet transited from the solar wind across the bow shock ...and close to the magnetopause on July 11, 2008. The observations suggest that the solar wind reconnection exhaust within the current sheet was disrupted by its interaction with the bow shock, while the subsequent compression of the current sheet against the magnetopause significantly reduced both the current sheet thickness and the plasma β and initiated reconnection at a new X‐line located within the magnetosheath. Furthermore, electrons were heated at the center of the magnetosheath exhaust, in contrast to the previously reported absence of electron heating in solar wind exhausts, but consistent with electron heating occasionally observed in association with magnetopause reconnection. This suggests that the level of electron heating in reconnection exhausts depends strongly on the boundary conditions.
Key Points
Triggers of magnetosheath reconnection identified
The bow shock disrupted reconnection
Magnetosheath reconnection heats electrons, unlike solar wind exhausts
Sea-Floor Spreading Event Captured by Seismometers Tolstoy, M; Cowen, J.P; Baker, E.T ...
Science (American Association for the Advancement of Science),
12/2006, Letnik:
314, Številka:
5807
Journal Article
Recenzirano
Two-thirds of Earth's surface is formed at mid-ocean ridges, yet sea-floor spreading events are poorly understood because they occur far beneath the ocean surface. At 9°50'N on the East Pacific Rise, ...ocean-bottom seismometers recently recorded the microearthquake character of a mid-ocean ridge eruption, including precursory activity. A gradual ramp-up in activity rates since seismic monitoring began at this site in October 2003 suggests that eruptions may be forecast in the fast-spreading environment. The pattern culminates in an intense but brief (~6-hour) inferred diking event on 22 January 2006, followed by rapid tapering to markedly decreased levels of seismicity.
Biological drugs are effective in patients with rheumatoid arthritis (RA), but increase severe infections. The CC chemokine receptor (CCR) 9 antagonist was effective for Crohn's disease without ...critical adverse effects including infections in clinical trials. The present study was carried out to explore the pathogenic roles of chemokine (C-C motif) ligand (CCL) 25 and its receptor, CCR9, in autoimmune arthritis and to study if the CCR9 antagonist could be a new treatment for RA.
CCL25 and CCR9 expression was examined with immunohistochemistry and Western blotting. Concentration of interleukin (IL)-6, matrix metalloproteinase (MMP)-3 and tumor necrosis factor (TNF)-α was measured with enzyme-linked immunosorbent assays. Effects of abrogating CCR9 on collagen-induced arthritis (CIA) was evaluated using CCR9-deficient mice or the CCR9 antagonist, CCX8037. Fluorescence labeled-CD11b+ splenocytes from CIA mice were transferred to recipient CIA mice and those infiltrating into the synovial tissues of the recipient mice were counted.
CCL25 and CCR9 proteins were found in the RA synovial tissues. CCR9 was expressed on macrophages, fibroblast-like synoviocytes (FLS) and dendritic cells in the synovial tissues. Stimulation with CCL25 increased IL-6 and MMP-3 production from RA FLS, and IL-6 and TNF-α production from peripheral blood monocytes. CIA was suppressed in CCR9-deficient mice. CCX8037 also inhibited CIA and the migration of transferred CD11b+ splenocytes into the synovial tissues.
The interaction between CCL25 and CCR9 may play important roles in cell infiltration into the RA synovial tissues and inflammatory mediator production. Blocking CCL25 or CCR9 may represent a novel safe therapy for RA.
Aims
Potassium homeostasis is essential for normal myocardial function, and low serum potassium may cause fatal arrhythmias. However, the association of low potassium and long-term mortality and ...morbidity in heart failure (HF) is largely unknown.
Methods and results
We studied 6845 HF patients in the Digitalis Investigation Group trial with serum potassium levels ≤5.5 mEq/L. Of these, 1189 had low potassium (<4 mEq/L). Propensity scores for low potassium were calculated for each patient and were used to match 1187 low-potassium patients with 1187 normal-potassium (4-5.5 mEq/L) patients. Effects of low potassium on outcomes were assessed using matched Cox regression analyses. All-cause mortality occurred in 379 (rate, 1103/10 000 person-years) normal-potassium and 441 (rate, 1330/10 000 person-years) low-potassium patients, respectively, during 3437 and 3315 years of follow-up hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.07-1.46; P = 0.006. Cardiovascular mortality occurred in 297 (864/10 000 person-years) normal-potassium and 356 (1074/10 000 person-years) low-potassium patients (HR, 1.27; 95% CI, 1.06-1.51; P = 0.009). Cardiovascular hospitalization occurred in 610 (rate, 2553/10 000 person-years) normal-potassium and 637 (rate, 2855/10 000 person-years) low-potassium patients (HR, 1.13; 95% CI, 0.99-1.29; P = 0.082).
Conclusion
In a cohort of ambulatory chronic systolic and diastolic HF patients who were balanced in all measured baseline covariates, serum potassium <4 mEq/L was associated with increased mortality, with a trend towards increased hospitalization.
Overexpression of the transcriptional coregulators C-terminal binding proteins 1 and 2 (CtBP1 and 2) occurs in many human solid tumors and is associated with poor prognosis. CtBP modulates oncogenic ...gene expression programs and is an emerging drug target, but its oncogenic role is unclear. Consistent with this oncogenic potential, exogenous CtBP2 transformed primary mouse and human cells to anchorage independence similarly to mutant H-Ras. To investigate CtBP's contribution to in vivo tumorigenesis, Apc
mice, which succumb to massive intestinal polyposis, were bred to Ctbp2
mice. CtBP interacts with adenomatous polyposis coli (APC) protein, and is stabilized in both APC-mutated human colon cancers and Apc
intestinal polyps. Ctbp2 heterozygosity increased the median survival of Apc
mice from 21 to 48 weeks, and reduced polyp formation by 90%, with Ctbp2
polyps exhibiting reduced levels of β-catenin and its oncogenic transcriptional target, cyclin D1. CtBP's potential as a therapeutic target was studied by treating Apc
mice with the CtBP small-molecule inhibitors 4-methylthio-2-oxobutyric acid and 2-hydroxy-imino phenylpyruvic acid, both of which reduced polyposis by more than half compared with vehicle treatment. Phenocopying Ctbp2 deletion, both Ctbp inhibitors caused substantial decreases in the protein level of Ctbp2, as well its oncogenic partner β-catenin, and the effects of the inhibitors on CtBP and β-catenin levels could be modeled in an APC-mutated human colon cancer cell line. CtBP2 is thus a druggable transforming oncoprotein critical for the evolution of neoplasia driven by Apc mutation.
Lagrangian shock hydrodynamics simulations will fail to proceed past a certain time if the mesh is approaching tangling. A common solution is an Arbitrary Lagrangian Eulerian (ALE) form, in which the ...mesh is improved (remeshing) and the solution is remapped onto the improved mesh. The simplest remeshing techniques involve moving only the nodes of the mesh. More advanced remeshing techniques involve altering the mesh connectivity in portions of the domain in order to prevent tangling. Work has been done using Voronoi-based polygonal mesh generators and 2D quad/triangle mesh adaptation. This paper presents the use of tetrahedral mesh adaptation methods as the remeshing step in an otherwise Lagrangian finite element shock hydrodynamics code called Alexa.
When the interplanetary magnetic field is northward for a period of time, O+ from the high‐latitude ionosphere escapes along reconnected magnetic field lines into the dayside magnetopause boundary ...layer. Dual‐lobe reconnection closes these field lines, which traps O+ and mass loads the boundary layer. This O+ is an additional source of magnetospheric plasma that interacts with magnetosheath plasma through magnetic reconnection. This mass loading and interaction is illustrated through analysis of a magnetopause crossing by the Magnetospheric Multiscale spacecraft. While in the O+‐rich boundary layer, the interplanetary magnetic field turns southward. As the Magnetospheric Multiscale spacecraft cross the high‐shear magnetopause, reconnection signatures are observed. While the reconnection rate is likely reduced by the mass loading, reconnection is not suppressed at the magnetopause. The high‐latitude dayside ionosphere is therefore a source of magnetospheric ions that contributes often to transient reduction in the reconnection rate at the dayside magnetopause.
Key Points
During sustained periods of northward IMF, O+ from the dayside high‐latitude ionosphere mass loads the boundary layer adjacent to the magnetopause
For the example shown, this mass loading is substantial and does have an effect on reconnection at the magnetopause when the IMF turns southward
This mass loading causes a transient reduction in the reconnection rate but does not suppress reconnection at the magnetopause
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