598 research outputs found
Adjusted empirical likelihood with high-order precision
Empirical likelihood is a popular nonparametric or semi-parametric
statistical method with many nice statistical properties. Yet when the sample
size is small, or the dimension of the accompanying estimating function is
high, the application of the empirical likelihood method can be hindered by low
precision of the chi-square approximation and by nonexistence of solutions to
the estimating equations. In this paper, we show that the adjusted empirical
likelihood is effective at addressing both problems. With a specific level of
adjustment, the adjusted empirical likelihood achieves the high-order precision
of the Bartlett correction, in addition to the advantage of a guaranteed
solution to the estimating equations. Simulation results indicate that the
confidence regions constructed by the adjusted empirical likelihood have
coverage probabilities comparable to or substantially more accurate than the
original empirical likelihood enhanced by the Bartlett correction.Comment: Published in at http://dx.doi.org/10.1214/09-AOS750 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Comparative study of preâcolumn derivatization liquid chromatography and post-column derivatization liquid chromatography for the determination of free formaldehyde residues in vaccines
Objective: To establish a preâcolumn derivatization liquid chromatography method and a postâcolumn derivatization liquid chromatography method for the determination of residual amount of free formaldehyde in vaccines. Consistency of the results of two methods was investigated. Methods: The preâcolumn derivatization liqâ uid chromatography was performed on a Shimadzu LCâ20AT liquid chromatograph (SPDâ20A UV detector). Sepaâ ration was accomplished on a Kromasil 100â5âC18(250mmĂ4.6mm) column with a mobile phase of 60% acetoniâ trile solution at a flow rate of 0. 8 mL·min-1 at 40â and the detection wavelength was 360 nm. The postâcolumn derivatization liquid chromatography was performed on a Shimadzu LCâ20AT liquid chromatograph (SPDâM20A diode array detector and vector derivative device). Separation was accomplished on a Chrom Core AQâC18 (250mm Ă4.6mm) column with a mobile phase of 0.2% (V/V) phosphoric acid solution at a flow rate of 1.0 mL·min-1 at 25â and the detection wavelength was 412 nm. The derivatization solution was acetate buffer, the flow rate was 0. 5 mL·min-1, and the temperature was 100â. The precision, repeatability and sample recovery of the two methods were investigated, and the experiment results were tested for significance by Fâtest and tâtest. Results: The precolumn derivatization liquid chromatography had good linearity in the range of 0. 025 -100ÎŒg· mL-1(R =0. 999 9, n =12). RSD values of precision and repeatability were 0. 06 % and 0.3%-1.4%, respectively. The average recoveries were 97. 3%-104. 8 % with RSD of 0. 7%-2. 9 %. The limit of quantitation was 0. 02ÎŒg·mL-1, and the limit of detection was 0. 01ÎŒg·mL-1. The postâcolumn derivatization liquid chromatogâ raphy had good linearity in the range of 0.025-100ÎŒg·mL-1 (R =0. 9999, n=12). RSD values of precision and repeatability were 0. 02% and 0. 0.7%-3.5 %, respectively. The average recoveries were 105. 6%-114. 6% with RSD of 0.3% - 1.9%. The limit of quantitation was 0. 02ÎŒg·mL-1, and the limit of detection was 0. 006ÎŒg·mL-1. The Fâtest and the tâtest results showed there was no significant difference between two methods. Conclusion: Two methods are simple and accurate with high sensitivity and good specificity, which can be applicable to the determination of free formaldehyde residues in vaccines
3D indoor scene modeling from RGB-D data: a survey
3D scene modeling has long been a fundamental problem in computer graphics and computer vision. With the popularity of consumer-level RGB-D cameras, there is a growing interest in digitizing real-world indoor 3D scenes. However, modeling indoor 3D scenes remains a challenging problem because of the complex structure of interior objects and poor quality of RGB-D data acquired by consumer-level sensors. Various methods have been proposed to tackle these challenges. In this survey, we provide an overview of recent advances in indoor scene modeling techniques, as well as public datasets and code libraries which can facilitate experiments and evaluation
Rate Compatible LDPC Neural Decoding Network: A Multi-Task Learning Approach
Deep learning based decoding networks have shown significant improvement in
decoding LDPC codes, but the neural decoders are limited by rate-matching
operations such as puncturing or extending, thus needing to train multiple
decoders with different code rates for a variety of channel conditions. In this
correspondence, we propose a Multi-Task Learning based rate-compatible LDPC
ecoding network, which utilizes the structure of raptor-like LDPC codes and can
deal with multiple code rates. In the proposed network, different portions of
parameters are activated to deal with distinct code rates, which leads to
parameter sharing among tasks. Numerical experiments demonstrate the
effectiveness of the proposed method. Training the specially designed network
under multiple code rates makes the decoder compatible with multiple code rates
without sacrificing frame error rate performance
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