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When plants die, neighbours escape competition. Living conspecifics could disproportionately benefit because they are freed from negative intraspecific processes; however, if the negative effects of past conspecific neighbours persist, other species might be advantaged, and diversity might be maintained through legacy effects. We examined legacy effects in a mapped forest by modelling the survival of 37,212 trees of 23 species using four neighbourhood properties: living conspecific, living heterospecific, legacy conspecific (dead conspecifics) and legacy heterospecific densities. Legacy conspecific effects proved nearly four times stronger than living conspecific effects; changes in annual survival associated with legacy conspecific density were 1.5% greater than living conspecific effects. Over 90% of species were negatively impacted by legacy conspecific density, compared to 47% by living conspecific density. Our results emphasize that legacies of trees alter community dynamics, revealing that prior research may have underestimated the strength of density dependent interactions by not considering legacy effects.
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Bosques , Densidad de Población , Árboles , Árboles/fisiología , Dinámica Poblacional , Modelos Biológicos , BiodiversidadRESUMEN
The realization and discovery of quantum spin liquid (QSL) candidate materials are crucial for exploring exotic quantum phenomena and applications associated with QSLs. Most existing metal-organic two-dimensional (2D) quantum spin liquid candidates have structures with spins arranged on the triangular or kagome lattices, whereas honeycomb-structured metal-organic compounds with QSL characteristics are rare. Here, we report the use of 2,5-dihydroxy-1,4-benzoquinone (X2dhbq, X = Cl, Br, H) as the linkers to construct cobalt(II) honeycomb lattices (NEt4)2[Co2(X2dhbq)3] as promising Kitaev-type QSL candidate materials. The high-spin d7 Co2+ has pseudospin-1/2 ground-state doublets, and benzoquinone-based linkers not only provide two separate superexchange pathways that create bond-dependent frustrated interactions but also allow for chemical tunability to mediate magnetic coupling. Our magnetization data show antiferromagnetic interactions between neighboring metal centers with Weiss constants from -5.1 to -8.5 K depending on the X functional group in X2dhbq linkers (X = Cl, Br, H). No magnetic transition or spin freezing could be observed down to 2 K. Low-temperature susceptibility (down to 0.3 K) and specific heat (down to 0.055 K) of (NEt4)2[Co2(H2dhbq)3] were further analyzed. Heat capacity measurements confirmed no long-range order down to 0.055 K, evidenced by the broad peak instead of the λ-like anomaly. Our results indicate that these 2D cobalt benzoquinone frameworks are promising Kitaev QSL candidates with chemical tunability through ligands that can vary the magnetic coupling and frustration.
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With the advancement of neural networks, more and more neural networks are being applied to structural health monitoring systems (SHMSs). When an SHMS requires the integration of numerous neural networks, high-performance and low-latency networks are favored. This paper focuses on damage detection based on vibration signals. In contrast to traditional neural network approaches, this study utilizes a stochastic configuration network (SCN). An SCN is an incrementally learning network that randomly configures appropriate neurons based on data and errors. It is an emerging neural network that does not require predefined network structures and is not based on gradient descent. While SCNs dynamically define the network structure, they essentially function as fully connected neural networks that fail to capture the temporal properties of monitoring data effectively. Moreover, they suffer from inference time and computational cost issues. To enable faster and more accurate operation within the monitoring system, this paper introduces a stochastic convolutional feature extraction approach that does not rely on backpropagation. Additionally, a random node deletion algorithm is proposed to automatically prune redundant neurons in SCNs, addressing the issue of network node redundancy. Experimental results demonstrate that the feature extraction method improves accuracy by 30% compared to the original SCN, and the random node deletion algorithm removes approximately 10% of neurons.
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Epilepsy is a common chronic neurological disorder worldwide. MicroRNAs (miRNAs) play an important role in the pathogenesis of epilepsy. However, the mechanism of the regulatory effect of miR-10a on epilepsy is unclear. In this study, we investigated the effect of miR-10a expression on the PI3K/Akt/mTOR signaling pathway and inflammatory cytokines in epileptic hippocampal neurons of rats. The miRNA differential expression profile of rat epileptic brain was analyzed using bioinformatic approaches. Neonatal Sprague-Dawley rat hippocampal neurons were prepared as epileptic neuron models in vitro by replacing culture medium with magnesium-free extracellular solution. The hippocampal neurons were transfected with miR-10a mimics, and transcript levels of miR-10a, PI3K, Akt and mTOR were detected by quantitative reverse transcription-PCR, and PI3K, mTOR, Akt, TNF-α, IL-1ß, IL-6 protein expression levels were detected by Western blot. Cytokines secretory levels were detected by ELISA. Sixty up-regulated miRNAs were identified in the hippocampal tissue of epileptic rats and might affect the PI3K-Akt signaling pathway. In the epileptic hippocampal neurons model, the expression levels of miR-10a were significantly increased, with decreasing levels of PI3K, Akt and mTOR, and increasing levels of TNF-α, IL-1ß and IL-6. The miR-10a mimics promoted the expression of TNF-α, IL-1ß and IL-6. Meanwhile, miR-10a inhibitor activated PI3K/Akt/mTOR pathway and inhibited cytokines secretion. Finally, cytokine secretion was increased by treated with PI3K inhibitor and miR-10a inhibitor. The miR-10a may promote inflammatory responses in rat hippocampal neurons by inhibiting the PI3K/Akt/mTOR pathway, suggesting that miR-10a may be one of the target therapeutic molecules for epilepsy treatment.
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Epilepsia , MicroARNs , Ratas , Animales , Proteínas Proto-Oncogénicas c-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Ratas Sprague-Dawley , Factor de Necrosis Tumoral alfa/metabolismo , Interleucina-6/metabolismo , Transducción de Señal , Serina-Treonina Quinasas TOR/metabolismo , Epilepsia/metabolismo , MicroARNs/metabolismo , Citocinas/metabolismo , Hipocampo/metabolismo , Neuronas/metabolismoRESUMEN
The propagation of spin waves in magnetically ordered systems has emerged as a potential means to shuttle quantum information over large distances. Conventionally, the arrival time of a spin wavepacket at a distance, d, is assumed to be determined by its group velocity, vg. Here, we report time-resolved optical measurements of wavepacket propagation in the Kagome ferromagnet Fe3Sn2 that demonstrate the arrival of spin information at times significantly less than d/vg. We show that this spin wave "precursor" originates from the interaction of light with the unusual spectrum of magnetostatic modes in Fe3Sn2. Related effects may have far-reaching consequences toward realizing long-range, ultrafast spin wave transport in both ferromagnetic and antiferromagnetic systems.
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Topologically protected magnon surface states are highly desirable as an ideal platform to engineer low-dissipation spintronics devices. However, theoretical prediction of topological magnons in strongly correlated materials proves to be challenging because the ab initio density functional theory calculations fail to reliably predict magnetic interactions in correlated materials. Here, we present a symmetry-based approach, which predicts topological magnons in magnetically ordered crystals, upon applying external perturbations such as magnetic/electric fields and/or mechanical strains. We apply this approach to carry out an efficient search for magnetic materials in the Bilbao Crystallographic Server, where, among 198 compounds with an over 300-K transition temperature, we identify 12 magnetic insulators that support room-temperature topological magnons. They feature Weyl magnons with surface magnon arcs and magnon axion insulators with either chiral surface or hinge magnon modes, offering a route to realize energy-efficient devices based on protected surface magnons.
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Previous studies have suggested that human exposure to bisphenol A (BPA) and soy isoflavones (SIFs) can occur during pregnancy. The combination of these chemicals is hypothesized to have a toxic impact on the fetus. While BPA is an industrial chemical used widely in the manufacture of polycarbonate plastics and epoxy resins, SIFs are naturally occurring estrogenlike phytoestrogens. To determine the impact of the combination of BPA and SIFs on fetal development, the body weight, organ weight, anogenital distance and histopathological changes in the testes of F1 offspring were assessed in mice. Hormonal effects were determined by measuring serum levels of estrogen receptor (ESR), folliclestimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T). Additionally, mitochondrial DNA copy numbers, and the serum levels of malondialdehyde and superoxide dismutase, were determined to evaluate alterations in oxidative stress and potential toxicity. Exposure to BPA increased the body weight of the pups and reduced the ratio of anogenital distance to body weight, as well as testes weight. Moreover, BPA exposure also induced testicular lesions. The seminiferous tubules of testis were denatured in varying degrees and the lumen wall structure was disordered. The levels of ESR in all offspring and the T levels in male offspring significantly increased, compared with controls. Coexposure to BPA and SIFs exacerbated these changes in body weight, testicular lesions and hormonal levels, relative to BPA exposure alone. Additionally, oxidative damage was only induced by highdose BPA. Collectively, these findings suggested that BPA and SIFs could have synergistic effect on the reproductive system, which could be mediated by the regulation of ESR expression and testosterone release.
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Compuestos de Bencidrilo/efectos adversos , Isoflavonas/efectos adversos , Fenoles/efectos adversos , Efectos Tardíos de la Exposición Prenatal/metabolismo , Animales , Femenino , Hormona Folículo Estimulante/sangre , Hormona Folículo Estimulante/metabolismo , Hormona Luteinizante/sangre , Hormona Luteinizante/efectos de los fármacos , Masculino , Malondialdehído/análisis , Malondialdehído/sangre , Ratones , Ratones Endogámicos , Tamaño de los Órganos/efectos de los fármacos , Estrés Oxidativo , Embarazo , Receptores de Estrógenos/sangre , Receptores de Estrógenos/efectos de los fármacos , Reproducción/efectos de los fármacos , Superóxido Dismutasa/análisis , Superóxido Dismutasa/sangre , Testículo/metabolismo , Testosterona/sangre , Testosterona/metabolismoRESUMEN
The discovery of 2-dimensional (2D) materials, such as CrI3, that retain magnetic ordering at monolayer thickness has resulted in a surge of both pure and applied research in 2D magnetism. Here, we report a magneto-Raman spectroscopy study on multilayered CrI3, focusing on two additional features in the spectra that appear below the magnetic ordering temperature and were previously assigned to high frequency magnons. Instead, we conclude these modes are actually zone-folded phonons. We observe a striking evolution of the Raman spectra with increasing magnetic field applied perpendicular to the atomic layers in which clear, sudden changes in intensities of the modes are attributed to the interlayer ordering changing from antiferromagnetic to ferromagnetic at a critical magnetic field. Our work highlights the sensitivity of the Raman modes to weak interlayer spin ordering in CrI3.
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BACKGROUND: Colon neuroendocrine tumors (NETs) are uncommon. Currently, the impact of the number of metastatic lymph nodes (LNs) and lymph node ratio (LNR) on survival has been well investigated in other colon malignancies, but both remain nebulous for patients with colon NETs. METHODS: Surgically resected patients with histologically proven nonmetastatic colon NETs were queried from the Surveillance, Epidemiology, and End Results database between 1988 and 2011. Patients with lymph nodes involved were investigated and categorized into four LNs-based classifications (≤4, >4-10, >10-13, and >13) or three LNR-based subgroups (≤0.51, >0.51-0.71, and >0.71) according to the threshold, determined by Harrell's C statistic. Univariate and multivariate survival analyses were performed by log-rank test and Cox stepwise regression analysis, respectively. RESULTS: Eight hundred fifty-one patients met the inclusion criteria. Among them, higher LNR and LNs classification are associated with a worse prognosis. The 10-year NETs-specific survival rate was 78.3% (74.2-82.6%), 61.3% (52.4-71.7%), 40.8% (20.7-80.7%) for patients in the ≤4, >4-10, and 10-13 LNs groups, respectively. When patients were classified with LNR, the observed 10-year NETs-specific survival rate was 79.9% (74.8-85.5%) for ≤0.51, 57.4% (43.8-75.2%) for >0.51-0.71, and 40.0% (31.0-51.5%) for >0.71. In stratified analysis, higher LNs and LNR groups have worse prognosis only in patients with advanced T stage (T3-T4). Regarding stage migration, the LNR-based system did not show superiority to LNs-based classification. CONCLUSIONS: Current TNM staging classification could be improved by considering the count of metastatic nodes and LNR instead of a simple record of lymph node status (N1 or N0) for colon NETs.
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Majorana bound states often occur at the end of a 1D topological superconductor. Validated by a new bulk invariant and an intuitive edge argument, we show the emergence of one Majorana Kramers pair at each corner of a square-shaped 2D topological insulator proximitized by an s_{±}-wave (e.g., Fe-based) superconductor. We obtain a phase diagram that addresses the relaxation of crystal symmetry and edge orientation. We propose two experimental realizations in candidate materials. Our scheme offers a higher-order and higher-temperature route for exploring non-Abelian quasiparticles.
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We report the discovery of a strong and tunable spin-lifetime anisotropy with excellent out-of-plane spin lifetimes up to 7.8 ns at 100 K in dual-gated bilayer graphene. Remarkably, this realizes the manipulation of spins in graphene by electrically controlled spin-orbit fields, which is unexpected due to graphene's weak intrinsic spin-orbit coupling (â¼12 µeV). We utilize both the in-plane magnetic field Hanle precession and oblique Hanle precession measurements to directly compare the lifetimes of out-of-plane vs in-plane spins. We find that near the charge neutrality point, the application of a perpendicular electric field opens a band gap and generates an out-of-plane spin-orbit field that stabilizes out-of-plane spins against spin relaxation, leading to a large spin-lifetime anisotropy (defined as the ratio between out-of-plane and in-plane spin lifetime) up to â¼12 at 100 K. This intriguing behavior occurs because of the unique spin-valley coupled band structure of bilayer graphene. Our results demonstrate the potential for highly tunable spintronic devices based on dual-gated 2D materials.
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Liver cancer is one of the leading causes of cancer associated mortality, particularly in eastern Asia. Autophagy serves an important role in carcinogenesis. Previous studies have reported that TRAP1 is a novel and efficient therapeutic target in various tumors. However, the associations between autophagy and TRAP1 is not clear. In the present study, autophagy activity and TRAP1 expression were examined in 4 different liver cancer cell lines (HepG2, Hep3B2.1-7, Sk-hep1 and HepG2.2.15) with or without rapamycin induction. The cell autophagy level was validated by monodansylcadaverine fluorescent staining, and the expression levels of Beclin1 and light chain (LC)-3-II/LC3-I. The mRNA and protein expression levels of tumor necrosis factor receptor-associated protein-1 (TRAP-1), Beclin1 and LC3-II/LC3-I were measured by reverse transcription-quantitative polymerase chain reaction, Protein Simple Western and western blot analysis. HepG2 cells, with medium invasive ability, exerted the highest basal level of autophagy and TRAP1 expression. In addition, hepatitis B (HBV) infection in HepG2 cells inhibited autophagy activity and TRAP1 expression. Rapamycin treatment also significantly enhanced autophagy in the 4 liver cancer cell lines and increased TRAP1 expression in HepG2, Hep3B2.1-7 and Sk-hep1 cells. Thus, the cell invasive ability, HBV infection and autophagy induction had different effects on TRAP1 expression, and TRAP1 may be associated with autophagy in liver cancer.
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This study investigated the association of PM2.5 exposure with VEGF by conducting a systematic review of existing literature and performing a meta-analysis. We searched all the studies published in the Cochrane Library, PUBMED, Embase, China National Knowledge Infrastructure China National Knowledge Infrastructure, and WanFang Electronic Database before June 2017. Finally six studies were identified. It confirmed that the increase in VEGF (ß = 1.23 pg/ml, 95% CI: 0.45, 2.01) was significantly associated with the PM2.5 mass concentration of 10 µg/m3. Studies from Canada showed that PM2.5 exposure statistically elevated the level of VEGF level that an increase of 1.20 pg/ml (95% CI: 0.88, 1.52) in VEGF was associated with per 10 µg/m3 increase in PM2.5 concentration. Other subgroup analyses indicated that the effects of PM2.5 exposure on VEGF differed per the in different exposure assessment methods, study designs, and study settings. It was concluded that elevated VEGF levels was significantly positive associated with PM2.5 exposure. Exposure assessment methods and study countries were the major sources of heterogeneity among studies.
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Exposición por Inhalación/efectos adversos , Material Particulado/efectos adversos , Factor A de Crecimiento Endotelial Vascular/sangre , Humanos , Exposición por Inhalación/análisis , Tamaño de la Partícula , Material Particulado/análisisRESUMEN
Topologically ordered phases of matter can host fractionalized excitations known as "anyons," which obey neither Bose nor Fermi statistics. Despite forming the basis for topological quantum computation, experimental access to these exotic phases has been very limited. We present a new route toward realizing fractionalized topological phases by literally building on unfractionalized phases, which are much more easily realized experimentally. Our approach involves a Kondo lattice model in which a gapped electronic system of noninteracting fermions is coupled to local moments via the exchange interaction. Using general entanglement-based arguments and explicit lattice models, we show that gapped spin liquids can be induced in the spin system, and we demonstrate the power of this "topological bootstrap" by realizing chiral and Z2 spin liquids. This technique enables the realization of many long sought-after fractionalized phases of matter.
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Gravitation is an important factor in maintaining cardiac contractility. Our study investigated whether simulated microgravity increases myocardial susceptibility to ischemia-reperfusion (IR) injury. Using the Langendorff-perfused heart model with 300 beats/min pacing, 4-week tail suspension (SUS) and control (CON) male Sprague-Dawley rats (n = 10 rats/group) were subjected to 60 min of left anterior descending coronary artery (LAD) occlusion followed by 120 min of reperfusion. Left ventricular end-systolic pressure (LVESP), left ventricular end-diastolic pressure (LVEDP), creatine kinase (CK) and lactate dehydrogenase (LDH) activity, and infarct size were assessed. Data demonstrated that there were significantly increased LVEDP, CK, LDH, and infarct size in SUS compared with CON (P < 0.05), accompanied by decreased LVESP (P < 0.05). Furthermore, TUNEL-positive cardiomyocytes were higher in SUS than that in CON (P < 0.01), and AMP-activated protein kinase (AMPK) phosphorylation and Bcl-2/Bax in SUS were less compared with CON (P < 0.05). Similarly, isolated hearts pre-treated with A-769662 exhibited better recovery of cardiac function, increased AMPK phosphorylation, and reduced necrosis and apoptosis. Furthermore, AMPKα protein showed a significant suppression in 4-week hindlimb unweighting rats. These results suggest that AMPK deficiency increases myocardial susceptibility to IR injury in rats subjected to simulated microgravity.
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Proteínas Quinasas Activadas por AMP/deficiencia , Daño por Reperfusión Miocárdica/enzimología , Daño por Reperfusión Miocárdica/fisiopatología , Simulación de Ingravidez , Proteínas Quinasas Activadas por AMP/metabolismo , Animales , Apoptosis , Autofagia , Compuestos de Bifenilo , Peso Corporal , Creatina Quinasa/metabolismo , Hemodinámica , Suspensión Trasera/efectos adversos , Preparación de Corazón Aislado , L-Lactato Deshidrogenasa/metabolismo , Masculino , Músculo Esquelético/metabolismo , Daño por Reperfusión Miocárdica/patología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/patología , Necrosis/patología , Fosforilación/efectos de los fármacos , Pironas/farmacología , Ratas , Tiofenos/farmacología , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
Motivated by recent experiments probing anomalous surface states of Dirac semimetals (DSMs) Na3Bi and Cd3As2, we raise the question posed in the title. We find that, in marked contrast to Weyl semimetals, the gapless surface states of DSMs are not topologically protected in general, except on time-reversal-invariant planes of surface Brillouin zone. We first demonstrate this finding in a minimal four-band model with a pair of Dirac nodes at [Formula: see text] where gapless states on the side surfaces are protected only near [Formula: see text] We then validate our conclusions about the absence of a topological invariant protecting double Fermi arcs in DSMs, using a K-theory analysis for space groups of Na3Bi and Cd3As2 Generically, the arcs deform into a Fermi pocket, similar to the surface states of a topological insulator, and this pocket can merge into the projection of bulk Dirac Fermi surfaces as the chemical potential is varied. We make sharp predictions for the doping dependence of the surface states of a DSM that can be tested by angle-resolved photoemission spectroscopy and quantum oscillation experiments.
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The anyonic excitations of a spin liquid can feature fractional quantum numbers under space group symmetries. Detecting these fractional quantum numbers, which are analogs of the fractional charge of Laughlin quasiparticles, may prove easier than the direct observation of anyonic braiding and statistics. Motivated by the recent numerical discovery of spin-liquid phases in the kagome Heisenberg antiferromagnet, we theoretically predict the pattern of space group symmetry fractionalization in the kagome lattice SO(3)-symmetric chiral spin liquid. We provide a method to detect these fractional quantum numbers in finite-size numerics which is simple to implement in the density matrix renormalization group. Applying these developments to the chiral spin liquid phase of a kagome Heisenberg model, we find perfect agreement between our theoretical prediction and numerical observations.
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Recently, there has been much effort in understanding topological phases of matter with gapless bulk excitations, which are characterized by topological invariants and protected intrinsic boundary states. Here we show that topological semimetals of Majorana fermions arise in exactly solvable Kitaev spin models on a series of three-dimensional lattices. The ground states of these models are quantum spin liquids with gapless nodal spectra of bulk Majorana fermion excitations. It is shown that these phases are topologically stable as long as certain discrete symmetries are protected. The corresponding topological indices and the gapless boundary states are explicitly computed to support these results. In contrast to previous studies of noninteracting systems, the phases discussed in this work are novel examples of gapless topological phases in interacting spin systems.
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To address the relationship of altered expression of double-strand break repair proteins Ku70 and p53 in clinical colorectal cancer (CRC), we examined the expression pattern of Ku70 and p53 by using fluorescent immunohistochemistry and real-time PCR assays in CRC and pericancerous samples from 152 Chinese patients. The results showed that down-expression pattern of both Ku70 and p53 coexisted in the CRC samples with significant correlating rate (R (2) = 0.9103; P < 0.001), and the down-expression of Ku70 and p53 was significantly associated with the advanced tumor node metastasis stage (Ku70: HR 3.453 in recurrence and 4.182 in survival, P < 0.001; P53: HR 3.114 in recurrence and 4.113 in survival, P < 0.001). The down-regulated Ku70 and p53 were associated with poor disease-free survival. Loss of Ku70 and p53 expression might serve as a biomarker of poor prognosis in CRC patients.
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Antígenos Nucleares/metabolismo , Biomarcadores de Tumor/metabolismo , Neoplasias Colorrectales/metabolismo , Proteínas de Unión al ADN/metabolismo , Recurrencia Local de Neoplasia/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Antígenos Nucleares/genética , Biomarcadores de Tumor/genética , Estudios de Casos y Controles , Neoplasias Colorrectales/mortalidad , Neoplasias Colorrectales/patología , Proteínas de Unión al ADN/genética , Femenino , Estudios de Seguimiento , Humanos , Técnicas para Inmunoenzimas , Autoantígeno Ku , Metástasis Linfática , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/mortalidad , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Pronóstico , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Tasa de Supervivencia , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Since topological insulators were theoretically predicted and experimentally observed in semiconductors with strong spin-orbit coupling, increasing attention has been drawn to topological materials that host exotic surface states. These surface excitations are stable against perturbations since they are protected by global or spatial/lattice symmetries. Following the success in achieving various topological insulators, a tempting challenge now is to search for metallic materials with novel topological properties. Here we predict that orthorhombic perovskite iridates realize a new class of metals dubbed topological crystalline metals, which support zero-energy surface states protected by certain lattice symmetry. These surface states can be probed by photoemission and tunnelling experiments. Furthermore, we show that by applying magnetic fields, the topological crystalline metal can be driven into other topological metallic phases, with different topological properties and surface states.