79 research outputs found

    Identification Robust Inference for the Risk Premium in Term Structure Models

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    We propose identification robust statistics for testing hypotheses on the risk premia in dynamic affine term structure models. We do so using the moment equation specification proposed for these models in Adrian et al. (2013). We extend the subset (factor) Anderson-Rubin test from Guggenberger et al. (2012) to models with multiple dynamic factors and time-varying risk prices. Unlike projection-based tests, it provides a computationally tractable manner to conduct identification robust tests on a larger number of parameters. We analyze the potential identification issues arising in empirical studies. Statistical inference based on the three-stage estimator from Adrian et al. (2013) requires knowledge of the factors' quality and is misleading without full-rank beta's or with sampling errors of comparable size as the loadings. Empirical applications show that some factors, though potentially weak, may drive the time variation of risk prices, and weak identification issues are more prominent in multi-factor models

    Macrophyte identity shapes water column and sediment bacterial community

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    By assembling mesocosms and utilizing high-throughput sequencing, we aim to characterize the shifts of the bacterial community in freshwaters driven by two contrasting submerged macrophyte species, Ceratophyllum demersum L. and Vallisneria spiralis L. Although the microbe in both the water column and sediment were largely modulated by the macrophyte, the effect varied considerably depending on bacterial locations and macrophyte species. Actinobacteria was the most abundant taxa in the water column of all the three treatments, but its abundances were significantly higher in the two planted treatments. Moreover, Alphaproteobacteria showed high abundance only in the unplanted control. For bacterial taxa in the sediment, C. demersum significantly increased the relative abundance of Anaerolineae but reduced the relative abundance of Betaproteobacteria and Gammaproteobacteria, while V. spiralis increased the relative abundance of Deltaproteobacteria and Gammaproteobacteria. Additionally, in the C. demersum treatment, the water column bacterial community increased more dramatically in richness, alpha diversity, and the relative abundance of the dominant taxa than those in the V. spiralis treatment. Taken together, the findings from this study reveal that the two species of submerged macrophyte modified the bacterial community in waters, despite the obvious interspecific performance differences

    Blur the Linguistic Boundary: Interpreting Chinese Buddhist Sutra in English via Neural Machine Translation

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    Buddhism is an influential religion with a long-standing history and profound philosophy. Nowadays, more and more people worldwide aspire to learn the essence of Buddhism, attaching importance to Buddhism dissemination. However, Buddhist scriptures written in classical Chinese are obscure to most people and machine translation applications. For instance, general Chinese-English neural machine translation (NMT) fails in this domain. In this paper, we proposed a novel approach to building a practical NMT model for Buddhist scriptures. The performance of our translation pipeline acquired highly promising results in ablation experiments under three criteria.Comment: This paper is accepted by ICTAI 2022. The 34th IEEE International Conference on Tools with Artificial Intelligence (ICTAI

    The impact of multiple driving factors on forest ecosystem services in karst desertification control

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    In the fragile karst desertification ecosystem, forests are the providers of eco-multifunctionality. And the ecosystem service (ES) supply capacity of forests is directly or indirectly affected by various driving factors. The aim of this study is to explore the driving role of forest spatial structure, species diversity, and functional diversity on ecosystem services. In this study, four forest types, namely, broad-leaved monoculture forest (planted economic forest) (F1), broad-leaved mixed forest (F2), coniferous and broad-leaved mixed forest (F3), and coniferous mixed forest (F4), were investigated in karst plateau mountain (KPM), karst plateau canyon (KPC), and karst mountain canyon (KMC) landforms. Variance analysis, correlation analysis and redundancy analysis were used to compare the differences of spatial structure, species diversity, functional diversity, and ES of different forest types and to clarify the driving role of spatial structure, species diversity, and functional diversity on ES. The results showed that the wood supply service of F3 was at least 4.27% higher than that of other forest types; carbon sequestration and oxygen release are at least 4.57 and 3.89% higher; the water holding capacity of litter and soil is higher by 6.24 and 2.26%, respectively; the soil OC, TN, TP, and TK were higher than 6.01, 1.22, 25.55, and 13.34%, respectively. The coniferous mixed forest and broadleaved mixed forest with a more complete spatial structure has a higher level of diversity, which can generate more wood and provide more soil nutrient sources, as well as stronger regulation capacity. Spatial structure affects plant productivity through interspecific relationships; soil fertility is restricted by the level of diversity; gas and water regulation are influenced by both spatial structure and diversity levels. There is a progressive driving relationship among spatial structure, diversity, and ES. In forest management, it is helpful to improve the forest ecosystem’s functioning by adjusting the forest structure using close-to-natural management measures

    Creep Properties of Expansive Soils under Triaxial Drained Conditions and its Nonlinear Constitutive Model

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    The creep behaviors of expansive soils play an important role in landslide prediction and long-term stability analysis. In this paper, triaxial drained compression creep tests of expansive soils were conducted on the improved stress-controlled triaxial apparatus. The test results show that only transient deformation and attenuation creep occur with low deviator stress, and the increment of axial strain increases exponentially with deviator stress increasing; while deviator stress reaches a certain value, attenuation creep, steady creep and accelerated creep all occur in a creep curve. Meanwhile, the volumetric strain presents the shear shrinkage characteristic at the initial stage of loading, and the shear shrinkage is small. With the extension of loading time, the volumetric strain gradually varies from shear contraction to dilatancy. When entering the accelerated creep stage, the development rate of volumetric strain increases sharply. Besides, isochronous stress-strain curves of expansive soils indicate that their creep process possesses nonlinear characteristics, and the nonlinear degree is related to creep time and stress level. Imitating the empirical formula of cyclic cumulative deformation of clay, a new nonlinear creep model is presented, which may well describe the creep property of expansive soils. Furthermore, critical failure stress could be obtained based on the proposed creep model. The ratio of the critical failure stress to conventional shear failure stress ranges from 70% to 80%, with average of 75.56%, therefore, critical failure stress may be estimated by conventional triaxial tests with the margin of error 5.5% within
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