Crustal deformation induced by mantle dynamics: insights from models of gravitational lithosphere removal

Mantle-based stresses have been proposed to explain the occurrence of deformation in the interior regions of continental plates, far from the effects of plate boundary processes. We examine how the gravitational removal of a dense mantle lithosphere root may induce deformation of the overlying crust. Simplified numerical models and a theoretical analysis are used to investigate the physical mechanisms for deformation and assess the surface expression of removal. Three behaviours are identified: (1) where the entire crust is strong, stresses from the downwelling mantle are efficiently transferred through the crust. There is little crustal deformation and removal is accompanied by surface subsidence and a negative free-air gravity anomaly. Surface uplift and increased free-air gravity occur after the dense root detaches. (2) If the mid-crust is weak, the dense root creates a lateral pressure gradient in the crust that drives Poiseuille flow in the weak layer. This induces crustal thickening, surface uplift and a minor free-air gravity anomaly above the root. (3) If the lower crust is weak, deformation occurs through pressure-driven Poiseuille flow and Couette flow due to basal shear. This can overthicken the crust, producing a topographic high and a negative free-air gravity anomaly above the root. In the latter two cases, surface uplift occurs prior to the removal of the mantle stress. The modeling results predict that syn-removal uplift will occur if the crustal viscosity is less than ∼10^(21) Pa s, corresponding to temperatures greater than ∼400–500 °C for a dry and felsic or wet and mafic composition, and ∼900 °C for a dry and mafic composition. If crustal temperatures are lower than this, lithosphere removal is marked by the formation of a basin. These results can explain the variety of surface expressions observed above areas of downwelling mantle. In addition, observations of the surface deflection may provide a way to constrain the vertical rheological structure of the crust

Magmatic expressions of continental lithosphere removal

Gravitational lithosphere removal in continental interior has been inferred from various observations, including anomalous surface deflections and magmatism. We use numerical models and a simplified theoretical analysis to investigate how lithosphere removal can be recognized in the magmatic record. One style of removal is a Rayleigh-Taylor-type instability, where removal occurs through dripping. The associated magmatism depends on the lithosphere thermal structure. Four types of magmatism are predicted: (1) For relatively hot lithosphere (e.g., back arcs), the lithosphere can be conductively heated and melted during removal, while the asthenosphere upwells and undergoes decompression melting. If removal causes significant lithospheric thinning, the deep crust may be heated and melted. (2) For moderately warm lithosphere (e.g., average Phanerozoic lithosphere) in which the lithosphere root has a low density, only the lithosphere may melt. (3) If the lithosphere root has a high density in moderately warm lithosphere, only asthenosphere melt is predicted. (4) For cold lithosphere (e.g., cratons), no magmatism is induced. An alternate style of removal is delamination, where dense lithosphere peels along Moho. In most cases, the lithosphere sinks too rapidly to melt. However, asthenosphere can upwell to the base of the crust, resulting in asthenospheric and crustal melts. In delamination, magmatism migrates laterally with the detachment point; in contrast, magmatism in Rayleigh-Taylor-type instability has a symmetric shape and converges toward the drip center. The models may explain the diversity of magmatism observed in areas with inferred lithosphere removal, including the Puna Plateau and the southern Sierra Nevada

Exploring the role of mindfulness on obligatory exercise among young athletes: mediating roles of obsessive passion and cognitive state anxiety

IntroductionIn the current trend toward youthfulness and age reduction in competitive sports, the issue of obligatory exercise among young athletes is becoming more severe. This not only affects their physical and mental health but also hampers their future prospects in the sports world. While delving into the impact of mindfulness on the issue of obligatory exercise among young athletes, it reveals the mediating role of obsessive passion and cognitive state anxiety.MethodsThis study is a cross-sectional research that employs convenience and snowball sampling methods. We selected 403 young athletes from several universities and high-level sports teams in the central-southern region of China as valid samples and used AMOS v.23 to construct a structural equation model to validate the hypotheses.ResultsThe research findings indicate a significant positive correlation between obsessive passion, cognitive state anxiety, and obligatory exercise. Furthermore, obsessive passion and cognitive state anxiety mediate the relationship between mindfulness and obligatory exercise. This implies that young athletes can better regulate their emotional state during training, manage training loads sensibly, and avoid issues with obligatory exercise through mindfulness training.DiscussionIn conclusion, to enhance the cognitive levels of young athletes and reduce their obligatory exercise behaviors, national sports authorities and coaching teams should develop reasonable mindfulness training programs for athletes and encourage their participation in mindfulness training

SGLT2 inhibitor plus DPP‐4 inhibitor as combination therapy for type 2 diabetes: A systematic review and meta‐analysis

To assess the efficacy and safety of sodium‐glucose co‐transporter 2 (SGLT2) inhibitors plus a dipeptidyl peptidase‐4 (DPP‐4) inhibitor in patients with type 2 diabetes mellitus (T2DM), we performed a systematic review and meta‐analysis of 14 randomized controlled trials (RCTs) involving 4828 patients. Compared with a DPP‐4 inhibitor, SGLT2 inhibitor/DPP‐4 inhibitor combination therapy was significantly associated with a decrease in glycaemic control (HbA1c, −0.71%; fasting plasma glucose [FPG], −25.62 mg/dL; postprandial plasma glucose, −44.00 mg/dL), body weight (−2.05 kg) and systolic blood pressure (−5.90 mm Hg), but an increase in total cholesterol (TC) of 3.24%, high‐density lipoprotein of 6.15% and low‐density lipoprotein of 2.55%. Adding a DPP‐4 inhibitor to an SGLT2 inhibitor could reduce HbA1c by −0.31%, FPG by −8.94 mg/dL, TC by −1.48% and triglycerides by −3.25%. Interestingly, low doses of an SGLT2 inhibitor in the combination has similar or even better efficacy in some aspects than high doses. Similar adverse events were observed for the combination therapy, with the exception of genital infection vs DPP‐4 inhibitor (risk ratio [RR], 5.31) and consistent genital infection vs an SGLT2 inhibitor (RR, 0.61). Further studies are warranted to confirm these results

Mindfulness, social evaluation anxiety, and self-regulation: exploring their association on impulsive behavior among athletes

IntroductionAthletes, due to frequent physical interactions in competitive sports, are prone to impulsive behavior. Impulsive behavior is a prevalent psychological factor in sports, often leading to performance-affecting errors. This cross-sectional survey investigated the relationship between mindfulness and athletes’ impulsive behavior.MethodsWe sampled 403 athletes from youth training centers, universities, sports academies, and clubs in China using convenience and snowball sampling. Using AMOS v23, we analyzed the data with a structural equation model.ResultsOur structural equation model confirmed that mindfulness and self-regulation inversely correlate with impulsive behavior, while social evaluation anxiety positively correlates with impulsive behavior. Furthermore, self-regulation and social evaluation anxiety serve as intermediaries in the link between mindfulness and impulsive behavior.DiscussionsThis research suggests introducing mindfulness meditation practices in competitive settings to improve athletes’ social evaluation anxiety and enhance their self-regulation abilities, thereby boosting their psychological health and curbing impulsive behavior