Human‐induced disturbances, including grazing and clipping, that cause defoliation are common in natural grasslands. Plant functional type differences in the ability to compensate for this tissue ...loss may influence interspecific competition.
To explore the effects of different intensities of clipping and nitrogen (N) addition on compensatory growth and interspecific competition, we measured accumulated aboveground biomass (AGB), belowground biomass (BGB), tiller number, non‐structural carbohydrates concentrations and leaf gas exchange parameters in two locally co‐occurring species (the C3 grass Leymus chinensis and the C4 grass Hemarthria altissima) growing in monoculture and in mixture.
For both grasses, the clipping treatment had significant impacts on the accumulated AGB, and the 40% clipping treatment had the largest effect. BGB gradually decreased with increasing defoliation intensity. Severe defoliation caused a significant increase in tiller number. Stored carbohydrates in the belowground biomass were mobilised and transported aboveground for the growth of new leaves to compensate for clipping‐induced injury. The net CO2 assimilation rate (A) of the remaining leaves increased with clipping intensity and peaked under clipping intensities of 20% or 40%. Nitrogen addition, at a rate of 10 g·N·m−2·year−1, enhanced A of the remaining leaves and non‐structural carbohydrate concentrations, which benefited plant compensatory growth, especially for the C3 grass. Under the mixed planting conditions, the clipping and N addition treatments lowered the competitive advantage of the C4 grass.
The results suggest that a combination of defoliation and N deposition have the potential to benefit the coexistence of C3 and C4 grasses.
The combination of defoliation and N deposition have the potential to benefit the coexistence of C3 and C4 grasses.
Genetic variants in the pharmacokinetic (PK) mechanism are the main underlying factors affecting the antiplatelet response to clopidogrel. Using a genomewide association study (GWAS) to identify new ...genetic loci that modify antiplatelet effects in Chinese patients with coronary heart disease, we identified novel variants in two transporter genes (SLC14A2 rs12456693, ATP‐binding cassette ABCA1 rs2487032) and in N6AMT1 (rs2254638) associated with P2Y12 reaction unit (PRU) and plasma active metabolite (H4) concentration. These new variants dramatically improved the predictability of PRU variability to 37.7%. The associations between these loci and PK parameters of clopidogrel and H4 were observed in additional patients, and its function on the activation of clopidogrel was validated in liver S9 fractions (P < 0.05). Rs2254638 was further identified to exert a marginal risk effect for major adverse cardiac events in an independent cohort. In conclusion, new genetic variants were systematically identified as risk factors for the reduced efficacy of clopidogrel treatment.
Free-electron lasers have been successfully operated with ultrahigh brightness and excellent transverse coherence at X-ray wavelengths. One of the next goals for further improvements is full ...coherence. An obvious approach is to seed the free-electron laser interaction using a conventional source that has good temporal coherence. Here, we show the first lasing of a free-electron laser with an echo-enabled harmonic generation scheme, which shows great promise for producing coherent lasing at short wavelengths, even in the X-ray regime. The experiment was conducted at a test facility that combines a 135.4 MeV electron accelerator with an amplifier consisting of a series of undulator magnets. Lasing was achieved at the third harmonic of the seed with a gain of ∼100,000 over spontaneous radiation. The measurements show typical exponential growth and excellent spectral characteristics, as well as good intensity stability.
Based on a rather simple macroscopic and statistical model, experimentally observed variations of yield stress at room temperature in various ODS alloys were theoretically reproduced. For the first ...time, yield stress values of ODS steels were calculated by taking into account: (1) two interaction mechanisms between dislocations and nanoprecipitates (shearing or bypassing, simultaneously, depending on the particle size); and (2) the whole, possibly multimodal, nanoparticle distributions experimentally determined by SANS. The relative importances of the various strengthening mechanisms can be easily deduced from these calculations.
Zircon geochemistry provides a sensitive monitor of its parental magma composition. However, due to the complexity of the uptake of trace elements during zircon growth, identifying source magmas ...remains challenging, particularly for detrital grains whose petrological context is lost. We use a machine learning-based approach to explore the classifiers for zircon provenance, based on 3794 published, high-quality zircon trace element analyses compiled from I-, S-, and A-type granites. Three supervised machine learning algorithms, namely, Support Vector Machine (SVM), Random Forest (RF), and Multilayer Perceptron (MLP) were used and trained with 11 features, including 7 trace elements (Ce, Eu, Ho, Nb, Ta, Th, and U) and 4 derived trace element ratios (Th/U, U/Yb, Ce/Ce*, and Eu/Eu*). Our results show that all three trained machine learning methods perform very well with accuracy varying from 0.86 to 0.89, and that input–output relationships captured by different ML methods are nearly consistent and can be explained by the known petrological processes. The application of our trained machine learning classifiers to detrital zircon studies will enhance the interpretability of zircon assemblages of different origins. It also helps develop interpretations, approaches, and tools that will benefit, for example, the study of continental crust evolution and mineral exploration.
Al-substituted
α-type nickel hydroxides with different interlayer anions (
NO
3
−
or
SO
4
2
−
) have been synthesized by chemical coprecipitation method. The microstructure and morphology of the ...prepared samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscope (SEM). The effect of interlayer anions on the electrochemical performance of the prepared nickel hydroxides were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results demonstrated that the Al-substituted
α-type nickel hydroxide with interlayer
NO
3
−
has better electrochemical performance, such as better reaction reversibility, higher proton diffuse coefficient, lower electrochemical impedance, higher specific capacity, and better cyclic stability, than that of the Al-substituted
α-type nickel hydroxide with interlayer
SO
4
2
−
.
Colitis-associated cancer (CAC) in inflammatory bowel diseases exhibits more aggressive behavior than sporadic colorectal cancer; however, the molecular mechanisms remain unclear. No definitive ...preventative agent against CAC is currently established in the clinical setting. We investigated the molecular mechanisms of CAC in the azoxymethane/dextran sulfate sodium (AOM/DSS) mouse model and assessed the antitumor efficacy of erlotinib, a small molecule inhibitor of the epidermal growth factor receptor (EGFR). Erlotinib premixed with AIN-93 G diet at 70 or 140 parts per million (ppm) inhibited tumor multiplicity significantly by 96%, with ∼60% of the treated mice exhibiting zero polyps at 12 weeks. Bulk RNA-sequencing revealed more than a thousand significant gene alterations in the colons of AOM/DSS-treated mice, with KEGG enrichment analysis highlighting 46 signaling pathways in CAC development. Erlotinib altered several signaling pathways and rescued 40 key genes dysregulated in CAC, including those involved in the Hippo and Wnt signaling. These findings suggest that the clinically-used antitumor agent erlotinib might be repurposed for suppression of CAC, and that further studies are warranted on the crosstalk between dysregulated Wnt and EGFR signaling in the corresponding patient population.
Display omitted
•Prophylactic erlotinib ingestion restricts colitis-associated cancer development.•Multiple inflammatory and immune signaling pathways contribute to CAC development.•Erlotinib modulates signaling pathways in the colon outside of EGFR inhibition.•Erlotinib rescues Wnt, Hippo and TGF-β signaling pathways dysregulated in CAC.•Prophylactic erlotinib may be an option to prevent CAC development in IBD.
The net rotation of Earth's lithosphere with respect to the underlying mantle is the longest‐wavelength component of toroidal flow in the mantle and is sensitive to both mantle buoyancy structure and ...lateral viscosity variations. The lithospheric net rotation in the geologic past implied by plate reconstructions using a hotspot reference frame for the past 100 Myr is up to five times greater than the present‐day rate of lithospheric net rotation. We explore the role of lateral viscosity variations associated with subcontinental keels in producing the lithospheric net rotation for the geologic past and find that the introduction of subcontinental keels improves the agreement between modeled net rotation and the net rotation present in the plate reconstructions for the past 25 Myr. However, our models with continental keels produce at most
0.16°/Myr of differential rotation between the lithosphere and lower mantle for present‐day, and explaining the most rapid rates of lithospheric net rotation during the Cretaceous and Paleogene remains challenging. This suggests the need for either an additional mechanism for generating lithospheric net rotation, or an adjustment to the absolute mantle reference frame relative to which plate motions are specified.
Key Points
Net rotation history can be explained for past 25 Myr
Rapid past net rotation requires new dynamical origin/revised reference frame
Net rotation requires careful treatment in models incorporating plate motions
We use a finite‐element model to solve for the response of Ganymede and Europa to tidal forcing from Jupiter, using various icy shell models with laterally variable (3‐D) structure. In all cases, the ...shell is assumed to be underlain by a liquid‐water ocean. Icy shells with laterally varying thickness are derived from a thermal conduction model. Three‐dimensional shear modulus profiles for the shell are built either from a conduction model or, for Europa, by assuming a hemispherical difference in composition. Icy shell structures with a nonglobal ocean are built for Ganymede. Using these shell structures to calculate the tidal response of Ganymede and Europa, we conclude the following: (1) the presence of lateral variations in thickness or in shear modulus would not degrade future attempts to use tidal observations to decide on the existence or absence of a liquid ocean and to determine the mean icy shell thickness. (2) Given accurate enough observations, the presence of lateral variations in thickness or in shear modulus could be determined by searching for nondegree‐2 components in the tidal response. (3) In the absence of significant viscous convective flow in the shell, the effects of a laterally varying shear modulus on the tidal response would be smaller than those of a laterally varying shell thickness. (4) If the shell is partially grounded, tidal observations of either gravity or uplift would be able to roughly differentiate regions where the ice is grounded from those where it is floating.
Key Points
Three‐dimensional structure would not affect attempts to detect a liquid ocean
Three‐dimensional structure would not affect attempts to determine the mean shell thickness
Presence of 3‐D structure could be inferred from nondegree‐2 tidal response
p70 S6 kinase (p70S6K) is best known for its regulatory roles in protein synthesis and cell growth by phosphorylating its primary substrate, ribosomal protein S6, upon mitogen stimulation. The ...enhanced expression/activation of p70S6K has been correlated with poor prognosis in some cancer types, suggesting that it may serve as a biomarker for disease monitoring. p70S6K is a critical downstream effector of the oncogenic PI3K/Akt/mTOR pathway and its activation is tightly regulated by an ordered cascade of Ser/Thr phosphorylation events. Nonetheless, it should be noted that other upstream mechanisms regulating p70S6K at both the post-translational and post-transcriptional levels also exist. Activated p70S6K could promote various aspects of cancer progression such as epithelial-mesenchymal transition, cancer stemness and drug resistance. Importantly, novel evidence showing that p70S6K may also regulate different cellular components in the tumor microenvironment will be discussed. Therapeutic targeting of p70S6K alone or in combination with traditional chemotherapies or other microenvironmental-based drugs such as immunotherapy may represent promising approaches against cancers with aberrant p70S6K signaling. Currently, the only clinically available p70S6K inhibitors are rapamycin analogs (rapalogs) which target mTOR. However, there are emerging p70S6K-selective drugs which are going through active preclinical or clinical trial phases. Moreover, various screening strategies have been used for the discovery of novel p70S6K inhibitors, hence bringing new insights for p70S6K-targeted therapy.
•p70S6K overexpression/activation is prognostically significant in some cancers.•Alternative splicing and non-coding RNAs emerge as important post-transcriptional mechanisms to regulate p70S6K.•p70S6K demonstrates potential roles in regulating the tumor microenvironment.•Several p70S6K-specific inhibitors have reached preclinical/clinical trial stages.•Different screening strategies are used to identify novel classes of p70S6K inhibitors.
PDF
