The Xicun kiln in Guangdong Province was a famous porcelain kiln in the Song Dynasty of China, and for years there has been controversy over the provenance of Xixun Qingbai wares. This paper analyses Qingbai samples from the Xicun, Hutian (Jingdezhen) and Chaozhou (Guangdong Province) kilns by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) and energy‐dispersive X‐ray fluorescence probe (EDXRF). The analytical results indicate that wares with a thin body excavated from the Xicun kiln site were produced in the Hutian kiln, and wares with a thick body were locally fired in Xicun; the contents of trace elements (V, Rb, Ba, Ta, Pb and Th) and the Nb/Ta ratio can be used to discriminate the products from the Xicun and Chaozhou kilns.
The wooden sluice site of the Nanyue Kingdom in Guangzhou,
China,
is covered with white magnesium sulfate salt whiskers continuously
growing from the surface. In this paper, polarizing microscopy, scanning
electron microscopy, infrared thermography, Fourier transform infrared
spectrometry, and surface tension analysis were utilized to comprehensively
analyze the micromorphology of whiskers grown on the surfaces of porous
materials collected at the site of Nanyue Kingdom, as well as the
change laws of magnesium sulfate solution droplets on the porous hydrophilic
matrix, and the migration and crystallization of magnesium sulfate
solution in the capillary tube. The diameters of magnesium sulfate
salt whiskers grown on the surfaces of porous samples range from 30
to 110 μm. For the first time, it is clear to see that the whisker’s
structure is hollow and nodular. There are solid crystalline salts
in hollow tubes, and some of them are aqueous. The top sections of
whiskers are approximately circular and are composed of particles
with a size of about 0.4–4.0 μm. Their growth conditions
are mainly characterized by the high humidity environment where the
porous material is located or locally located, the formation of an
annular whisker base, and the pressure difference generated during
the formation progress of water-bearing crystals in the capillary
of the whisker. The research results expound on the circumstances
and mechanism of magnesium sulfate solution-induced whisker development
on the surface of porous materials, providing a reference for the
study of the whisker growth mechanism.
Doubly robust (DR) estimation is a crucial technique in causal inference and missing data problems. We propose a novel Propensity score Augmentved Doubly robust (PAD) estimator to enhance the commonly used DR estimator for average treatment effect on the treated (ATT), or equivalently, the mean of the outcome under covariate shift. Our proposed estimator attains a lower asymptotic variance than the conventional DR estimator when the propensity score (PS) model is misspecified and the outcome regression (OR) model is correct while maintaining the double robustness property that it is valid when either the PS or OR model is correct. These are realized by introducing some properly calibrated adjustment covariates to linearly augment the PS model and solving a restricted weighted least square (RWLS) problem to minimize the variance of the augmented estimator. Both the asymptotic analysis and simulation studies demonstrate that PAD can significantly reduce the estimation variance compared to the standard DR estimator when the PS model is wrong and the OR is correct, and maintain close performance to DR when the PS model is correct. We further applied our method to study the effects of eligibility for 401(k) plan on the improvement of net total financial assets using data from the Survey of Income and Program Participation of 1991.
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