Adakite is an intermediate to felsic rock with low K, high Al, Na and Sr, and depleted in Y and HREE, usually occurring in arc settings related to subduction of an oceanic slab. Here we report the ...occurrence of potassic adakites from south Tibet in an orogenic belt produced by the Indo–Asian continent collision. These adakitic intrusives, as a product of Neogene east–west extension, occur in a Miocene Cu-bearing porphyry belt, which developed along the Gangdese arc paralleling the Yarlung–Zangbo suture, but is locally controlled by NS-striking normal faulting systems. Available age data define a duration of magmatism of 10–18 Ma for the adakitic intrusives and related extrusive analogues in south Tibet, which occur in a post-collisional extensional setting. Geochemical data indicate that these adakitic intrusives are shoshonitic and exhibit calc-alkaline composition with high K, and high Sr/Y and La/Y coupled with low Y and HREE, similar to adakites derived from slab melting. However, a wide range for ϵNd(t) (−6.18 to +5.52), initial 87Sr/86Sr (0.7049–0.7079), 207Pb/204Pb (15.502–15.626), and 208Pb/204Pb (38.389–38.960), as well as high K2O contents (2.6–8.6 wt%) and relatively high Mg# values (0.32–0.74) indicate that these adakitic magmas were formed by a complex mechanism involving partial melting of mafic materials in a thickened lower crust with input of enriched mantle and/or upper crust components. Absence of a negative Eu anomaly, extreme depletion in Y, Nb and Ti, and variable high Sr/Y and La/Yb ratios suggest that the lower crustal source is probably a hydrous amphibole eclogite or garnet amphibolite, as exhumed in the western and eastern Himalayan syntaxes on the Tibetan plateau. Partial melting of the lower crust was most likely triggered by mantle-derived ultra-potassic magmatism (17–25 Ma) formed by slab breakoff or mantle thinning. During the formation and migration of pristine adakitic melts, additional input of ultra-potassic magmas and upper crustal materials could account for the observed ϵNd–ϵSr signatures and high Rb/Sr, K and Mg# characteristics for most of the adakitic intrusives in south Tibet.
Grazing by livestock greatly affects the soil carbon (C) cycle in grassland ecosystems. However, the effects of grazing at different intensities and durations on the dynamics of soil C in its subsoil ...layers are not clearly understood. Here, we compiled data from 78 sites (in total 122 published studies) to examine the effects of varying grazing intensities and durations on soil C content at different depths for grasslands in China. Our meta‐analysis revealed that grazing led to an overall decrease in soil C content and productivity of above‐ground vegetation (e.g., above‐ground biomass and litter) but an increase in below‐ground biomass. Specifically, the effects of grazing on soil C content became less negative or even positive with increasing soil depths. An increase of soil C content was consequently found under light grazing (LG), although soil C content still decreased under moderate and heavy grazing. The increase in soil C content under LG could be largely attributed to the increase of soil C content in subsoil layers (>20 cm), despite that soil C content in surface soil layer (0–20 cm) decreased. Moreover, the magnitude of increase in soil C content under LG in subsoil layers increased with grazing duration. A possible reason of the increase in soil C content in the subsoil layers was due to the increases in below‐ground biomass. Our study highlights that LG may modify the allocation of C input and promote its accumulation in subsoil layers, thus offsetting the negative impact of grazing on surface soil C content, a finding that has significant implications for C sequestration in grasslands.
Light grazing (LG) increased the soil C content (SCC) owing to its positive effect on SCC in subsoil layers (>20 cm), although its effect in the surface soil layer (0–20 cm) was negative. A possible reason is that LG may promote the below‐ground biomass (BGB) in subsoil layers (>20 cm), offsetting the negative impact on above‐ground biomass (AGB) and litter. Blue downward pointing arrows represent decrease and red upward pointing arrows represent increase in the variables. SWC: soil water content.
Intervertebral disc degeneration (IDD) is a chronic, complex process associated with low back pain; mechanisms of its occurrence have not yet been fully elucidated. Its process is not only ...accompanied by morphological changes, but also by systematic changes in its histological and biochemical properties. Many cellular and molecular mechanisms have been reported to be related with IDD and to reverse degenerative trends, abnormal conditions of the living cells and altered cell phenotypes would need to be restored. Promising biological therapeutic strategies still rely on injection of active substances, gene therapy and cell transplantation. With advanced study of tissue engineering protocols based on cell therapy, combined use of seeding cells, bio‐active substances and bio‐compatible materials, are promising for IDD regeneration. Recently reported progenitor cells within discs themselves also hold prospects for future IDD studies. This article describes the background of IDD, current understanding and implications of potential therapeutic strategies.
Attention-deficit/hyperactivity disorder (ADHD), which is characterized by core symptoms of inattention and hyperactivity/impulsivity, is one of the most common neurodevelopmental disorders of ...childhood. Neuroimaging studies have suggested that these behavioral disturbances are associated with abnormal functional connectivity among brain regions. However, the alterations in the structural connections that underlie these behavioral and functional deficits remain poorly understood. Here, we used diffusion magnetic resonance imaging and probabilistic tractography method to examine whole-brain white matter (WM) structural connectivity in 30 drug-naive boys with ADHD and 30 healthy controls. The WM networks of the human brain were constructed by estimating inter-regional connectivity probability. The topological properties of the resultant networks (e.g., small-world and network efficiency) were then analyzed using graph theoretical approaches. Nonparametric permutation tests were applied for between-group comparisons of these graphic metrics. We found that both the ADHD and control groups showed an efficient small-world organization in the whole-brain WM networks, suggesting a balance between structurally segregated and integrated connectivity patterns. However, relative to controls, patients with ADHD exhibited decreased global efficiency and increased shortest path length, with the most pronounced efficiency decreases in the left parietal, frontal, and occipital cortices. Intriguingly, the ADHD group showed decreased structural connectivity in the prefrontal-dominant circuitry and increased connectivity in the orbitofrontal-striatal circuitry, and these changes significantly correlated with the inattention and hyperactivity/impulsivity symptoms, respectively. The present study shows disrupted topological organization of large-scale WM networks in ADHD, extending our understanding of how structural disruptions of neuronal circuits underlie behavioral disturbances in patients with ADHD.
In order to assess the left ventricular (LV) longitudinal rotation (LR) in primary hypertension (PH) patients with a normal LV ejection fraction. Conventional echocardiography was performed in 61 ...healthy subjects and 64 PH patients. The apical four-chamber views in these patients were acquired by GE-Vivid7 or E9, then the peak radial strain in the systolic period and the strain rate in systole, in early and late diastolic periods, were measured. Segmental LR and global LR were assessed by using two-dimensional speckle tracking imaging (2D-STI). The peak radial strain rate in the early diastolic period in PH patients was significantly lower than that in healthy subjects. The rotational degrees of the middle and base lateral, the apex and the middle septum walls in PH patients were significantly different from those of the healthy subjects. The healthy subjects had prominent counter-clockwise LR (0.29°±2.86°) and the PH patients had prominent clockwise LR (-2.13°±2.93°) in non-LV wall hypertrophy and (-2.43°±2.66°) in LV wall hypertrophy. The time delay between the LV lateral wall and the septum wall in PH patients correlated to the peak LR. We concluded that 2D-STI can assess the time delay between the LV lateral wall and the septum wall to the peak LR and clockwise LR in patients with PH, and prove that PH patients have a clockwise LR. By this, we conclude that in PH patients, the LV early systolic function have changed.
Background
The longitudinal associations of sleep timing and time in bed (TIB) with dementia and cognitive decline in older adults are unclear.
Methods
This population‐based cohort study used data ...from 1982 participants who were aged ≥60 years, free of dementia, and living in rural communities in western Shandong, China. At the baseline (2014) and follow‐up (2018) examinations, sleep parameters were assessed using standard questionnaires. Cognitive function was measured using the Mini‐Mental State Examination (MMSE). Dementia was diagnosed following the DSM‐IV criteria, and the NIA‐AA criteria for Alzheimer disease (AD). Data were analyzed using restricted cubic splines, Cox proportional‐hazards models, and general linear models.
Results
During the mean follow‐up of 3.7 years, dementia was diagnosed in 97 participants (68 with AD). Restricted cubic spline curves showed J‐shaped associations of sleep duration, TIB, and rise time with dementia risk, and a reverse J‐shaped association with mid‐sleep time. When sleep parameters were categorized into tertiles, the multivariable‐adjusted hazard ratio (HR) of incident dementia was 1.69 (95%CI 1.01–2.83) for baseline sleep duration >8 hours (vs. 7–8 h), 2.17 (1.22–3.87) for bedtime before 9 p.m. (vs. 10 p.m. or later), and 2.00 (1.23–3.24) for mid‐sleep time before 1 a.m. (vs. 1–1.5 a.m.). Early bedtime and mid‐sleep time were significantly associated with incident AD (HR range: 2.25–2.51; p < 0.05). Among individuals who were free of dementia at follow‐up, baseline long TIB, early bedtime and mid‐sleep time, early and late rise time, and prolonged TIB and advanced bedtime and mid‐sleep time from baseline to follow‐up were associated with a greater decline in MMSE score (p < 0.05). These associations with cognitive decline were statistically evident mainly among men or participants who were aged 60–74 years.
Conclusions
Long TIB and early sleep timing are associated with an increased risk of dementia, and the associations with greater cognitive decline are evident only among older people aged 60–74 years and men.
Tendon/ligament injuries are very common in sports and other rigorous activities. Tendons regenerate and repair slowly and inefficiently in vivo after injury. The limited ability of tendon to ...self-repair and the general inefficiencies of current treatment regimes have hastened the motivation to develop tissue-engineering strategies for tissue repair. Of particular interest in recent years has been the use of adult mesenchymal stem cells (MSCs) to regenerate functional tendons and ligaments. Different sources of MSCs have been studied for their effects on tendon repair. However, ectopic bone and tumour formation has been reported in some special circumstances after transplantation of MSCs. The induction of MSCs to differentiate into tendon-forming cells in vitro prior to transplantation is a possible approach to avoid ectopic bone and tumour formation while promoting tendon repair. While there are reports about the factors that might promote tenogenic differentiation, the study of tenogenic differentiation is hampered by the lack of definitive biomarkers for tendons. This review aims to summarize the cell sources currently used for tendon repair as well as their advantages and limitations. Factors affecting tenogenic differentiation were summarized. Molecular markers currently used for assessing tenogenic differentiation or neotendon formation are summarized and their advantages and limitations are commented upon. Finally, further directions for promoting and assessing tenogenic differentiation of stem cells for tendon repair are discussed.
The sit-to-stand test (STST) has been used to evaluate the exercise tolerance of patients with COPD. However, mutual comparisons to predict poor exercise tolerance have been hindered by the variety ...of STST modes used in previous studies, which also did not consider patients' subjective perceptions of different STST modes. Our aim was to compare the five-repetition sit-to-stand test (5STS) with the 30-second sit-to-stand test (30STS) for predicting poor performance in the six-minute walking test and to evaluate patients' subjective perceptions to determine the optimal mode for clinical practice.
Patients with stable COPD performed 5STS, 30STS and the 6MWT and then evaluated their feelings about the two STST modes by Borg dyspnea score and a questionnaire. Moreover, we collected data through the pulmonary function test, mMRC dyspnea score, COPD assessment test and quadriceps muscle strength (QMS). A receiver operating characteristic curve analysis of the 5STS and 30STS results was used to predict 6-minute walk distance (6MWD) <350 m.
The final analysis included 128 patients. Similar moderate correlations were observed between 6MWT and 5STS (
=-0.508,
<0.001) and between 6MWT and 30STS (
=0.528,
<0.001), and there were similar correlations between QMS and 5STS (
=-0.401,
<0.001) and between QMS and 30STS (
=0.398,
<0.001). The 5STS and 30STS score cutoffs produced sensitivity, specificity and positive and negative predictive values of 76.0%, 62.8%, 56.7% and 80.3% (5STS) and 62.0%, 75.0%, 62.0% and 75.0% (30STS), respectively, for predicting poor 6MWT performance. The 5STS exhibited obvious superiority in terms of the completion rate and the subjective feelings of the participants.
As a primary screening test for predicting poor 6MWD, the 5STS is similar to the 30STS in terms of sensitivity and specificity, but the 5STS has a better patient experience.
•Sandblasting micromachines titanium in favorable combination of microroughness and microhardness.•Ca- and P-containing coating is deposited on titanium by optimized composite technique.•Sandblasting ...promotes properties of titanium MAO coatings.•Nanostructure hydroxyapatite is deposited on as-prepared coating in SBF.
Sandblasting is one of the most effective methods to modify a metal surface and improve its properties for application. Micro-arc oxidation (MAO) could produce a ceramic coating on a dental implant, facilitating cellular differentiation and osseocomposite on it. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by an optimum composite technique to improve the bioactive performance. The effect of sandblasting intensity on microstructures and properties of the implant coatings is examined, and the modified surfaces are characterized in terms of their topography, phase, chemical composition, mechanical properties and hydroxyapatite (HA)-inducing ability. The results show that a moderate sandblasting micromachines the substrate in favorable combination of rough and residual stresses; its MAO coating deposits nano-hydroxyapatite after immersion in simulated body fluid (SBF) for 5 days exhibiting better bioactivity. The further improvement of the implant surface performance is attributed to an optimized composite technique.
•Perform an accelerated degradation test with smart electricity meter samples.•Fit regression models of the degradation paths of data from degradation indicators.•Predict the degradation to failure ...by a performance threshold of samples.•Build an accelerated degradation function of the stressors .•Evaluate the lower bound reliable lifetime of SEM samples.
The smart electricity meter (SEM) is one of the most critical elements of smart grids. The billing function of SEM is one of its most important functions to its operators and end-users. Because the SEM devices need to be highly reliable, in this study we conduct accelerated degradation tests (ADTs) for the prediction of SEM reliability with respect to the billing function. For designing the ADTs, we have identified five key modules and their components, two performance indicators, and three possible degradation stressors. Six ADTs are conducted under different configurations of the stressors. The test data are then used to fit degradation paths by linear regression models. Extrapolation to the failure threshold allows the prediction of the Time-to-Failure of SEM. Finally, the reliable lifetime of the SEM is predicted by an accelerated degradation function which is obtained by fitting a Weibull failure time distribution.
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