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CrSbSe3âthe only experimentally validated one-dimensional (1D) ferromagnetic semiconductorâhas recently attracted significant attention. However, all reported synthesis methods for CrSbSe3 nanocrystals are based on top-down methods. Here we report a template selection strategy for the bottom-up synthesis of CrSbSe3 nanoribbons. This strategy relies on comparing the formation energies of potential binary templates to the ternary target product. It enables us to select Sb2Se3 with the highest formation energy, along with its 1D crystal structure, as the template instead of Cr2Se3 with the lowest formation energy, thereby facilitating the transformation from Sb2Se3 to CrSbSe3 by replacing half of the Sb atoms in Sb2Se3 with Cr atoms. The as-prepared CrSbSe3 nanoribbons exhibit a length of approximately 5 µm, a width ranging from 80 to 120 nm, and a thickness of about 5 nm. The single CrSbSe3 nanoribbon presents typical semiconductor behavior and ferromagnetism, confirming the intrinsic ferromagnetism in the 1D CrSbSe3 semiconductor.
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As a globally invasive quarantine pest, the cotton mealybug, Phenacoccus solenopsis, is spreading rapidly, posing serious threats against agricultural and forestry production and biosecurity. In recent years, the niche conservatism hypothesis has been widely debated, which is particularly evident in invasive biology research. Identifying the niche dynamics of P. solenopsis, as well as assessing its global invasion risk, is of both theoretical and practical importance. Based on 462 occurrence points and 19 bioclimatic variables, we used n-dimensional hypervolume analysis to quantify the multidimensional climatic niche of this pest in both its native and invasive ranges. We examined niche conservatism and further optimized the MaxEnt model parameters to predict the global invasion risk of P. solenopsis under both current and future climate conditions. Our findings indicated that the niche hypervolume of this pest in invasive ranges was significantly larger than that in its native ranges, with 99.45% of the niche differentiation contributed by niche expansion, with the remaining less than 1% explained by space replacement. Niche expansion was most evident in Oceania and Eurasia. The area under the receiver operating characteristic curve (0.83) and true skill statistic (0.62) indicated the model's robust performance. The areas of suitable habitats for P. solenopsis are increasing significantly and the northward spread is obvious in future climate change scenarios. North Africa, northern China, Mediterranean regions, and northern Europe had an increased invasion risk of P. solenopsis. This study provided scientific support for the early warning and control of P. solenopsis.
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Similar to the magnetic topological insulator of MnBi2Te4, recent studies have demonstrated that VBi2Te4 is also an ideal candidate to explore many intriguing quantum states. Different from the strong interlayer antiferromagnetic (AFM) coupling in layered MnBi2Te4, based on first-principles calculations, we find that the energy difference between AFM and ferromagnetic (FM) orders in layered VBi2Te4 is much smaller than that of MnBi2Te4. Specifically, it is found that the interlayer FM coupling can be readily achieved by applying strain. Further electronic band structures reveal that the VBi2Te4 bilayer is a time-reversal symmetry broken quantum spin Hall insulator with a spin Chern number of CS = 1, which is essentially different from the QAH state with a Chern number of C = 1 in the MnBi2Te4 bilayer. Most strikingly, the topological states of the magnetic VBi2Te4 bilayer can be well tuned by strain, whose topological phase diagram is mapped out as a function of strain by employing continuum model analyses. All of these results indicate that the layered VBi2Te4 not only enriches the family of magnetic topological materials, but also provides a promising platform to explore more exotic quantum phenomena.
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The cotton mealybug Phenacoccus solenopsis, a globally invasive insect, is listed as a national quarantine pest in agriculture and forestry, which seriously threatens biological safety of China. Niche conservatism is a key assumption of species distribution model. An evaluation of the applicability of using ecological niche models to assess the invasion risk of cotton mealybug, and further optimizing model complexity, are of both theoretical and practical significance. Based on 706 occurrence records and key bioclimatic variables, we used n-dimensional hypervolume niche analysis method to quantify the climatic niche hypervolumes of this pest in both native and invasive sites, and further tested the niche conservatism hypothesis. MaxEnt model parameters were optimized to predict the invasion risk of the mealybug under current and future climate scenarios in China. The results showed that four climatic variables (annual mean temperature, mean temperature of wettest quarter, mean temperature of warmest quarter, and precipitation of driest quarter) were the key climate factors affecting the distribution of cotton mealybug. Compared with native climatic niche (hypervolume volume, HV=40.43), the niche hypervolume of cotton mealybug in the invasive areas was significantly reduced (HV=6.04). Niche contraction (the net differences between the amount of space enclosed by each hypervolume was 0.84) explained 98.8% of niche differentiation, whereas niche shift (the replacement of space between hypervolumes was 0.01) contributed less than 2%. The direction of climatic niche contraction of the pest in different invasive areas was not exactly consistent. The default parameters of MaxEnt model were unreliable (ΔAICc=14.27), and the optimal parameter combination was obtained as follows: feature combination was linear-quadratic-hinge-product and regularization multiplier was 0.5. The most suitable habitats of cotton mealybug were concentrated in the south of Huaihe River-Qinling Mountains line, and the north-central provinces contained a large area of low suitable habitat. The increase of suitable habitat was not significant at the end of 21 century (SSP1-2.6: 1.7%, SSP5-8.5: 0.7%). The multidimensional climatic niche of P. solenopsis was highly conservative. The species distribution model was suitable for analyzing its invasion risk. The northward spread was obvious, and climate change had less impact on the pest.
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Hormigas , Gossypium , Animales , Agricultura , China , Cambio ClimáticoRESUMEN
The recently discovered magnetic topological insulator of MnBi2Te4(MBT), has been demonstrated to realize the quantum anomalous Hall (QAH) effect, while the naturally antiferromagnetic (AFM) interlayer coupling in MBT results in that the QAH effect can only be realized in odd-layered systems and at low temperature. Using first-principles calculations, we find that intercalating Bi2Te3(BT) layers into MBT by forming MBT/(BT)n/MBT (n= 1-6) heterostructures can induce magnetic phase transition from AFM to ferromagnetic (FM) interlayer coupling whenn⩾ 3. Specifically, MBT/(BT)3/MBT and MBT/(BT)4/MBT respectively host Curie temperaturesTcof 14 K and 11 K, which fits well the experimentally measuredTcof 12 K. Detailed band structure calculations and topological identification show that the QAH phases are well preserved for all FM heterostructures. And the topological mechanism of MBT/(BT)n/MBT as a function ofnis revealed by employing continuum model analysis. Most importantly, the FM MBT/(BT)4/MBT has already been experimentally fabricated. Thus, our work provides a practical guideline to explore high-temperature QAH effect in MBT family of materials.
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In this work, we use first-principles calculations to determine the interplay between spin-orbit coupling (SOC) and magnetism which can not only generate a quantum anomalous Hall state but can also result in topologically trivial states although some honeycomb systems host large band gaps. By employing tight-binding model analysis, we have summarized two types of topologically trivial states: one is due to the coexistence of quadratic non-Dirac and linear Dirac bands in the same spin channel that act together destructively in magnetic materials (such as, CrBr3, CrCl3, and VBr3 monolayers); the other one is caused by the destructive coupling effect between two different spin channels due to small magnetic spin splitting in heavy-metal-based materials, such as, BaTe(111)-supported plumbene. Further investigations reveal that topologically nontrivial states can be realized by removing the Dirac band dispersion of the magnetic monolayers for the former case (such as in alkali metal doped CrBr3), while separating the two different spin channels from each other by enhancing the magnetic spin splitting for the latter case (such as in half-iodinated silicene). Thus, our work provides a theoretical guideline to manipulate the topological states in a two-dimensional honeycomb lattice.
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In this paper, we consider a slot-controlled coded compressed sensing protocol for unsourced massive random access (URA) that concatenates a shared patterned Reed-Muller (PRM) inner codebook to an outer error-correction code. Due to the limitations of the geometry-based decoding algorithm in single-sequence settings and due to the message interference that may result in decreased decoding performance under multi-sequence circumstances, a list PRM projection algorithm and an iterative list PRM projection algorithm are proposed to supplant the signal detector associated with the inner PRM sequences in this paper. In detail, we first propose an enhanced path-saving algorithm, called list PRM projection detection, for use in single-user scenarios that maintains multiple candidates during the first few layers so as to remedy the risk of spreading errors. On this basis, we further propose an iterative list PRM projection algorithm for use in multi-user scenarios. The vectors for PRM codes and channel coefficients are jointly detected in an iterative manner, which offers significant improvements regarding the convergence rate for signal recovery. Furthermore, the performances of the proposed algorithms are analyzed mathematically, and we verify that the theoretical simulations are consistent with the numerical simulations. Finally, we concatenate the inner PRM codes that employ iterative list detection in two practical error-correction outer codes. According to the simulation results, we conclude that the packetized URA with the proposed iterative list projection detection works better than benchmarks in terms of the number of active users it can support in each slot and the amount of energy needed per bit to meet an expected error probability.
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We propose a novel slot-pattern-control based coded compressed sensing for unsourced random access with an outer A-channel code capable of correcting t errors. Specifically, an RM extension code called patterned Reed-Muller (PRM) code is proposed. We demonstrate the high spectral efficiency due to its enormous sequence space and prove the geometry property in the complex domain that enhances the reliability and efficiency of detection. Accordingly, a projective decoder based on its geometry theorem is also proposed. Next, the "patterned" property of the PRM code, which partitions the binary vector space into several subspaces, is further extended as the primary principle for designing a slot control criterion that reduces the number of simultaneous transmissions in each slot. The factors affecting the chance of sequence collisions are identified. Finally, the proposed scheme is implemented in two practical outer A-channel codes: (i) the t-tree code and (ii) the Reed-Solomon code with Guruswami-Sudan list decoding, and the optimal setups are determined to minimize SNR by optimizing the inner and outer codes jointly. In comparison with the existing counterpart, our simulation results confirm that the proposed scheme compares favorably with benchmark schemes regarding the energy-per-bit requirement to meet a target error probability as well as the number of accommodated active users in the system.
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Algoritmos , Reproducibilidad de los Resultados , Matemática , Simulación por ComputadorRESUMEN
Black phosphorus (BP), a fascinating semiconductor with high mobility and a tunable direct bandgap, has emerged as a candidate beyond traditional silicon-based devices for next-generation electronics and optoelectronics. The ability to grow large-scale, high-quality BP films is a prerequisite for scalable integrated applications but has thus far remained a challenge due to unmanageable nucleation events. Here we develop a sustained feedstock release strategy to achieve subcentimetre-size single-crystal BP films by facilitating the lateral growth mode under a low nucleation rate. The as-grown single-crystal BP films exhibit high crystal quality, which brings excellent field-effect electrical properties and observation of pronounced Shubnikov-de Haas oscillations, with high mobilities up to ~6,500 cm2 V-1 s-1 at low temperatures. We further extend this approach to the growth of single-crystal BP alloy films, which broaden the infrared emission regime of BP from 3.7 µm to 6.9 µm at room temperature. This work will greatly facilitate the development of high-performance electronics and optoelectronics based on BP family materials.
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A cost-effective, highly regioselective and metal-free version for the synthesis of indolizine derivatives by means of Tf2O-mediated cascade reaction of pyridyl-enaminones and thiophenols/thioalcohols under mild reaction conditions has been reported. Diverse electron-rich indolizine derivatives could be obtained in up to 94% yield via the selective 1,4-addition of vinyl iminium triflate tandem cyclization/aromatization, which allowed the simultaneous construction of C-N and C-S/and one example of C-Se bonds.
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As a crucial concept in magnetism and spintronics, exchange bias (ExB) measures the asymmetry in the hysteresis loop of a pinned ferromagnet (FM)/antiferromagnet (AFM) interface. Previous studies are mainly focused on FM/AFM heterostructures composed of conventional bulk materials, whose complex interfaces prohibit precise control and full understanding of the phenomenon. Here, the enabling power of 2D magnets is exploited to demonstrate the emergence, non-aging, extendability, and rechargeability of ExB in van der Waals Fe3 GeTe2 homostructures, upon moderate pressuring. The emergence of the ExB is attributed to a local stress-induced FM-to-AFM transition, as validated using first-principles calculations, and confirmed in magneto-optical Kerr effect and second harmonic generation measurements. It is also observed that, negligible ExB aging before the training effect suddenly takes place through avalanching, pronounced delay of the avalanche via timed pressure repetition (extendability), ExB recovery in the post-training sample upon refreshed pressuring (rechargeability), and demonstrate its versatile tunability. These striking findings offer unprecedented insights into the underlying principles of ExB and its training, with immense technological applications in sight.
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ABSTRACT Introduction: The epidemic has impacted the pace of teaching in colleges and universities, especially in physical education practical classes. Both online physical education and students' spontaneous exercise are restricted by space and infrastructure, making it necessary to seek guidelines for adjusting sports training. Objective: Investigate the current status of physical exercise by college students during the epidemic period, exploring data management strategies for the guidance of actions in exercise practice by colleges and universities. Methods: An online questionnaire survey was conducted among college and university students from different regions. The online data were entered, sorted, and analyzed using the questionnaire platform in question and Excel software. Results: The college students-maintained exercise frequency between three to seven sessions per week, with an average duration of 30 to 90 minutes in each session. As for the effect of the exercises performed, after optimal training, the theoretical exercise score was 3.74 points, the exercise capacity score was 3.68 points, and the actual exercise capacity score was 2.96 points. A score of 3.89 points was obtained for self-regulation and 4.23 points for stress regulation. However, due to the limits imposed by the local infrastructure and the fact that the online teaching content is slightly adapted to the real situation, it still requires adjustments. Conclusion: Colleges and universities should strengthen sports data management, manage the situation and students' physical needs in a timely manner, and provide targeted guidance to students' movements. Adjustments of methods and content to online teaching should consider the actual needs of students, providing better sports support to students during the epidemic. Level of evidence II; Therapeutic studies - investigating treatment outcomes.
RESUMO Introdução: A epidemia impactou o ritmo de ensino nas faculdades e universidades, especialmente nas aulas práticas de educação física. Tanto a educação física on-line quanto o exercício físico espontâneo dos estudantes são restringidos pelo espaço e pela infraestrutura, fazendo-se necessária a busca de orientações para o ajuste dos treinamentos esportivos. Objetivo: Investigar o estado atual dos exercícios físicos pelos estudantes universitários durante o período da epidemia, explorando estratégias de gestão dos dados para uma orientação de ações na prática de exercício pelas faculdades e universidades. Métodos: Foi realizada uma pesquisa por questionário online entre estudantes de faculdades e universidades de diferentes regiões. Através da plataforma do questionário em questão e do software Excel, os dados on-line foram introduzidos, classificados e analisados. Resultados: Os estudantes universitários mantiveram a frequência de exercícios entre três a sete sessões semanais, com média de duração de 30 minutos a 90 minutos em cada sessão. Quanto ao efeito dos exercícios praticados, após o treinamento otimizado, a pontuação teórica do exercício foi de 3,74 pontos, a pontuação da capacidade de exercício foi de 3,68 pontos, e a pontuação da capacidade real de exercício foi de 2,96 pontos. Obteve-se 3.89 pontos para a autorregulação e 4.23 pontos para a regulação do estresse. Entretanto, devido aos limites impostos pela infraestrutura local e ao fato de que o conteúdo do ensino on-line está ligeiramente adaptado à situação real, ainda exige adequações. Conclusão: As faculdades e universidades devem fortalecer a gestão de dados esportivos, administrar a situação e as necessidades físicas dos estudantes em tempo hábil, fornecendo orientação dirigida aos movimentos dos estudantes. Os ajustes de métodos e conteúdo ao ensino on-line devem considerar as necessidades reais dos estudantes, fornecendo um melhor apoio esportivo aos estudantes durante a epidemia. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.
RESUMEN Introducción: La epidemia ha impactado en el ritmo de la enseñanza en colegios y universidades, especialmente en las clases prácticas de educación física. Tanto la educación física en línea como el ejercicio espontáneo de los estudiantes están restringidos por el espacio y la infraestructura, lo que hace necesario buscar directrices para ajustar el entrenamiento deportivo. Objetivo: Investigar el estado actual del ejercicio físico de los estudiantes universitarios durante el periodo epidémico, explorando estrategias de gestión de datos para una orientación de acciones en la práctica de ejercicio por parte de colegios y universidades. Métodos: Se realizó una encuesta por cuestionario en línea entre estudiantes de colegios y universidades de diferentes regiones. Los datos en línea se introdujeron, clasificaron y analizaron utilizando la plataforma de cuestionarios correspondiente y el programa informático Excel. Resultados: Los estudiantes universitarios mantuvieron una frecuencia de ejercicio entre tres y siete sesiones semanales, con una duración media de 30 minutos a 90 minutos en cada sesión. En cuanto al efecto de los ejercicios realizados, tras el entrenamiento optimizado, la puntuación teórica del ejercicio fue de 3,74 puntos, la puntuación de la capacidad de ejercicio fue de 3,68 puntos y la puntuación de la capacidad de ejercicio real fue de 2,96 puntos. Se obtuvieron 3,89 puntos para la autorregulación y 4,23 puntos para la regulación del estrés. Sin embargo, debido a los límites impuestos por la infraestructura local y al hecho de que el contenido de la enseñanza en línea está ligeramente adaptado a la situación real, aún requiere ajustes. Conclusión: Los institutos y universidades deben reforzar la gestión de los datos deportivos, gestionar oportunamente la situación y las necesidades físicas de los estudiantes, y proporcionar orientación específica a los movimientos de los estudiantes. Los ajustes de métodos y contenidos a la enseñanza en línea deben considerar las necesidades reales de los estudiantes, proporcionando un mejor apoyo deportivo a los estudiantes durante la epidemia. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.
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Realization of ferromagnetic (FM) interlayer coupling in magnetic topological insulators (TIs) of the MnBi2Te4 family of materials (MBTs) may pave the way for realizing the high-temperature quantum anomalous Hall effect (high-T QAHE). Here we propose a generic dual d-band (DDB) model to elucidate the energy difference (ΔE = EAFM - EFM) between the AFM and FM coupling in transition-metal (TM)-doped MBTs, where the valence of TMs splits into d-t2g and d-eg sub-bands. Remarkably, the DDB shows that ΔE is universally determined by the relative position of the dopant (X) and Mn d-eg/t2g bands, . If ΔEd > 0, then ΔE > 0 and the desired FM coupling is favored. This surprisingly simple rule is confirmed by first-principles calculations of hole-type 3d and 4d TM dopants. Significantly, by applying the DDB model, we predict the high-T QAHE in the V-doped Mn2Bi2Te5, where the Curie temperature is enhanced by doubling of the MnTe layer, while the topological order mitigated by doping can be restored by strain.
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The gas path fault diagnosis is considered widely to ensure the economy, safety and practicability of gas turbines. Traditional gas path diagnosis methods are vulnerable to various uncertainties, resulting in a deviation between the diagnostic results and the real states, which brings huge potential safety hazard to industrial production. Periodic analysis can suppress the uncertainty interference and extract accurately the features of performance parameters to improve the accuracy of health evaluation. Motivated by these, a novel periodic analysis method is proposed for detecting gas path faults, namely the changing periodicity of performance parameters representing the health state of gas turbine is detected to determine whether gas path fault occurs. It is theoretically analyzed that the relationship between the periodicity of observed performance parameters and that of boundary conditions, system uncertainties, and thermodynamic parameters. The simulation experiments are performed to analyze the effects of gas path faults on periodicity of boundary conditions, system uncertainties and thermodynamic parameters. The results show that most gas path faults break the periodicity of performance parameters, proving that the operating states can be monitored through the periodic analysis of performance parameters. An online diagnosis procedure is further proposed by combining signal decomposition and rolling periodic extraction method to judge whether the gas turbine is in health or not. The validity is verified by comparing the periodicity of performance parameters under healthy and fault states. Periodic analysis suppresses the effects of system and parameter uncertainties and detects sensitively gas path faults, which provides a new idea for the fault diagnosis of gas turbines.
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Magnetic heterostructures offer great promise in spintronic devices due to their unique magnetic properties, such as exchange bias effect, topological superconductivity, and magneto-resistance. Although various magnetic heterostructures including core/shell, multilayer, and van der Waals systems have been fabricated recently, the construction of perfect heterointerfaces usually rely on complicated and high-cost fabrication methods such as molecular-beam epitaxy; surprisingly, few one-dimensional (1D) bimagnetic heterojunctions, which provide multidegrees of freedom to modulate magnetic properties via magnetic anisotropy and interface coupling, have been fabricated to date. Here we report a one-pot solution-based method for the synthesis of ferromagnetic/antiferromagnetic/ferromagnetic heterojunction nanorods with excellent heterointerfaces in the case of Cr2Te3/MnTe/Cr2Te3. The precise control of homogeneous nucleation of MnTe and heterogeneous nucleation of Cr2Te3 is a key factor in synthesizing this heterostructure. The resulting 1D bimagnetic heterojunction nanorods exhibit high coercivity of 5.8 kOe and exchange bias of 892.5 Oe achieved by the magnetic MnTe/Cr2Te3 interface coupling.
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OBJECTIVE: To investigate the association between body mass index (BMI) and all-cause mortality in a Chinese rural population. DESIGN: Prospective cohort study. SETTING: This study was conducted from 2003 to 2018 in Anqing, Anhui Province, China. PARTICIPANTS: 17 851 participants aged 25-64 years (49.4% female) attending physical examinations and questionnaire were included in this study. The inclusion criterion was families having a minimum of three participating siblings. The exclusion criteria included participants without family number and BMI data at baseline. OUTCOME MEASURES: The outcome measure was all-cause mortality. Generalized estimating equation (GEE) regression analysis was performed to determine the association between baseline BMI and all-cause mortality. RESULTS: During a mean follow-up period of 14.1 years, 730 deaths (8.0%) occurred among men, and 321 deaths (3.6%) occurred among women. The mean BMI for males was 21.3[Formula: see text] kg/m2, and for female it was 22.1±3.1 kg/m2. Baseline BMI was significantly inversely associated with all-cause mortality risk for per SD increase (OR, 0.79 (95% CI, 0.72 to 0.87) for males; OR, 0.88 (95% CI, 0.76 to 1.01) for females). When BMI was stratified with cut points at 20 and 24 kg/m2, compared with the low BMI group, a significantly lower risk of death was found in the high BMI group (BMI ≥24: OR, 0.57 (95% CI, 0.43 to 0.77) in males; 0.65 (95% CI, 0.46 to 0.93) in females) after adjustment for relevant factors. CONCLUSIONS: In this relatively lean rural Chinese population, the risk of all-cause mortality decreased with increasing BMI. The excess risk of all-cause mortality associated with a high BMI was not seen among this rural population.
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Mortalidad , Población Rural , Adulto , Índice de Masa Corporal , China/epidemiología , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Masculino , Estudios Prospectivos , Factores de RiesgoRESUMEN
Although Pb harbors a strong spin-orbit coupling effect, pristine plumbene (the last group-IV cousin of graphene) hosts topologically trivial states. Based on first-principles calculations, we demonstrate that epitaxial growth of plumbene on the BaTe(111) surface converts the trivial Pb lattice into a quantum spin Hall (QSH) phase with a large gap of â¼0.3 eV via a selective substrate-orbital-filtering effect. Tight-binding model analyses show the pz orbital in half of the Pb overlayer is selectively removed by the BaTe substrate, leaving behind a pz-px,y band inversion. Based on the same working principle, the gap can be further increased to â¼0.5-0.6 eV by surface adsorption of H or halogen atoms that filters out the other half of the Pb pz orbitals. The mechanism of selective substrate-orbital-filtering is general, opening an avenue to explore large-gap QSH insulators in heavy-metal-based materials. It is worth noting that plumbene has already been widely grown on various substrates experimentally.
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BACKGROUND: According to the Global Burden of Disease Study 2017, smoking is one of the leading four risk factors contributing to deaths in China. We aimed to evaluate the associations of smoking with all-cause mortality in a Chinese rural population. METHODS: Male participants over age 45 (n = 5367) from a large familial aggregation study in rural China, were included in the current analyses. A total of 528 former smokers and 3849 current smokers accounted for 10 and 71.7% of the cohort, respectively. Generalized Estimating Equations were used to evaluate the association between baseline smoking status and mortality, adjusting for pertinent covariates. RESULTS: There were 579 recorded deaths during the 15-year follow-up. Current smokers (odds ratio [OR],1.60; 95% CI,1.23-2.08) had higher all-cause mortality risks than nonsmokers. Relative to nonsmokers, current smokers of more than 40 pack-years ([OR],1.85; 95% CI,1.33-2.56) had a higher all-cause mortality risk. Compared to nonsmokers, current smokers who started smoking before age 20 ([OR],1.91; 95% CI,1.43-2.54) had a higher all-cause mortality risk, and former smokers in the lower pack-year group who quit after age 41 (median) ([OR],3.19; 95% CI,1.83-5.56) also had a higher risk of death after adjustment. Furthermore, former smokers who were also former drinkers had the highest significant risk of mortality than never smokers or drinkers. (P for interaction = 0.034). CONCLUSIONS: This study provides evidence that current smokers and former smokers have a higher mortality risk than nonsmokers and would benefit from cessation at a younger age.
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Fumar Cigarrillos , Adulto , China/epidemiología , Estudios de Cohortes , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Población Rural , Adulto JovenRESUMEN
A norm version of the RMSProp algorithm with penalty (termed RMSPropW) is introduced into the deep learning framework and its convergence is addressed both analytically and numerically. For rigour, we consider the general nonconvex setting and prove the boundedness and convergence of the RMSPropW method in both deterministic and stochastic cases. This equips us with strict upper bounds on both the moving average squared norm of the gradient and the norm of weight parameters throughout the learning process, owing to the penalty term within the proposed cost function. In the deterministic (batch) case, the boundedness of the moving average squared norm of the gradient is employed to prove that the gradient sequence converges to zero when using a fixed step size, while with diminishing stepsizes, the minimum of the gradient sequence converges to zero. In the stochastic case, due to the boundedness of the weight evolution sequence, it is further shown that the weight sequence converges to a stationary point with probability 1. Finally, illustrative simulations are provided to support the theoretical analysis, including a comparison with the standard RMSProp on MNIST, CIFAR-10, and IMDB datasets.
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Algoritmos , Bases de Datos Factuales , Aprendizaje Profundo , Bases de Datos Factuales/normas , Bases de Datos Factuales/estadística & datos numéricos , Aprendizaje Profundo/normas , HumanosRESUMEN
Recent advances in copper chalcogenide-based nanocrystals (NCs), copper sulfide, and copper selenide derived nanostructures, have drawn considerable attention. However, reports of crystal phase and shape engineering of binary or ternary copper telluride NCs remain rare. Here, a colloidal hot-injection approach for producing binary copper/tin telluride, and ternary copper tin telluride NCs with controllable compositions, crystal structures, and morphologies is reported. The crystal phase and growth behavior of these tellurides are systematically studied from both experimental and theoretical perspectives. The morphology of Cu1.29 Te NCs is modified from 1D nanorods with different aspect ratios to 2D nanosheets and 3D nanocubes, by controlling the preferential growth of specific crystalline facets. A controllable phase transition from Cu1.29 Te to Cu1.43 Te NCs is also demonstrated. The latter can be further converted into Cu2 SnTe3 and SnTe through Sn incorporation. Temperature dependent thermoelectric properties of metal (Cu and Sn) telluride nanostructure thin films are also studied, including Cu1.29 Te, Cu1.43 Te, Cu2 SnTe3 , and SnTe. Cu2 SnTe3 is a low carrier density semimetal with compensating electron and hole Fermi surface pockets. The engineering of crystal phase and morphology control of colloidal copper tin telluride NCs opens a path to explore and design new classes of copper telluride-based nanomaterials for thermoelectrics and other applications.