Background: Novel preclinical models for prediction of osteoarthritis-like pain are necessary for the elucidation of osteoarthritis (OA) pathology and for assessment of novel analgesics. A widely used behavioral test ...Background: Novel preclinical models for prediction of osteoarthritis-like pain are necessary for the elucidation of osteoarthritis (OA) pathology and for assessment of novel analgesics. A widely used behavioral test in rat models of tibiofemoral OA is hind limb weight bearing (WB). However, this method evaluates WB in an unnaturally restricted manner. The aim of this study was therefore to characterize the Tekscan Pressure Measurement System as a means to assess OA-like tibiofemoral pain in rats by determination of plantar pressure distribution in a more natural and unrestricted position, defined as unrestricted WB. Methods: Intra-articular injections of 1 mg monosodium iodoacetate (MIA) or saline were administrated in the left hind knee of 84 male Sprague Dawley rats. Changes in unrestricted WB between ipsilateral and contralateral hindlimbs were determined. Morphine (5 mg/kg administered subcutaneously) and naproxen (60 mg/kg per-oral) were examined for their ability to reverse WB changes. Results: Changes in hind limb unrestricted WB were observed 14 (P P P Conclusion: This study indicated that unrestricted WB assessed by the Tekscan system can be utilized as a clinically relevant method to assess aberrations in WB induced by intra-articular MIA injections in rodents. Therefore, this system may be useful for understanding the mechanisms of OA pain in humans and may also assist in the discovery of novel pharmacological agents.展开更多
Multivariate seemingly unrelated regression system is raised first and the two stage estimation and its covariance matrix are given. The results of the literatures[1-5] are extended in this paper.
Based on historical aerial photography of three periods and together with field investigation, the status of desertification development after the 1950s in the Mu Us sandland was analyzed, the difference of the desert...Based on historical aerial photography of three periods and together with field investigation, the status of desertification development after the 1950s in the Mu Us sandland was analyzed, the difference of the desertification developing speed at two stages was compared, and its possible causes were explored. The results show that the developing speed of desertification from the late 1970s to the early 1990s is apparently slowed down, compared with that from the late 1950s to the late 1970s and there exists an obvious recovery trend at the second stage. The difference between the two stages accounts for severely over-reclaiming, over-grazing and unrestricted cutting during the first stage, which are the main causes of desertification development in the semi-arid steppe and arid desert steppe areas.展开更多
The double-threshold autoregressive conditional heteroscedastic(DTARCH) model is a useful tool to measure and forecast the mean and volatility of an asset return in a financial time series. The DTARCH model can handle...The double-threshold autoregressive conditional heteroscedastic(DTARCH) model is a useful tool to measure and forecast the mean and volatility of an asset return in a financial time series. The DTARCH model can handle situations wherein the conditional mean and conditional variance specifications are piecewise linear based on previous information. In practical applications, it is important to check whether the model has a double threshold for the conditional mean and conditional heteroscedastic variance. In this study, we develop a likelihood ratio test based on the estimated residual error for the hypothesis testing of DTARCH models. We first investigate DTARCH models with restrictions on parameters and propose the unrestricted and restricted weighted composite quantile regression(WCQR) estimation for the model parameters. These estimators can be used to construct the likelihood ratio-type test statistic. We establish the asymptotic results of the WCQR estimators and asymptotic distribution of the proposed test statistics. The finite sample performance of the proposed WCQR estimation and the test statistic is shown to be acceptable and promising using simulation studies. We use two real datasets derived from the Shanghai and Shenzhen Composite Indexes to illustrate the methodology.展开更多
This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/ licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction ...This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/ licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.展开更多
文摘Background: Novel preclinical models for prediction of osteoarthritis-like pain are necessary for the elucidation of osteoarthritis (OA) pathology and for assessment of novel analgesics. A widely used behavioral test in rat models of tibiofemoral OA is hind limb weight bearing (WB). However, this method evaluates WB in an unnaturally restricted manner. The aim of this study was therefore to characterize the Tekscan Pressure Measurement System as a means to assess OA-like tibiofemoral pain in rats by determination of plantar pressure distribution in a more natural and unrestricted position, defined as unrestricted WB. Methods: Intra-articular injections of 1 mg monosodium iodoacetate (MIA) or saline were administrated in the left hind knee of 84 male Sprague Dawley rats. Changes in unrestricted WB between ipsilateral and contralateral hindlimbs were determined. Morphine (5 mg/kg administered subcutaneously) and naproxen (60 mg/kg per-oral) were examined for their ability to reverse WB changes. Results: Changes in hind limb unrestricted WB were observed 14 (P P P Conclusion: This study indicated that unrestricted WB assessed by the Tekscan system can be utilized as a clinically relevant method to assess aberrations in WB induced by intra-articular MIA injections in rodents. Therefore, this system may be useful for understanding the mechanisms of OA pain in humans and may also assist in the discovery of novel pharmacological agents.
基金Supported by the NSF of Henan Province(0611052600)
文摘Multivariate seemingly unrelated regression system is raised first and the two stage estimation and its covariance matrix are given. The results of the literatures[1-5] are extended in this paper.
文摘Based on historical aerial photography of three periods and together with field investigation, the status of desertification development after the 1950s in the Mu Us sandland was analyzed, the difference of the desertification developing speed at two stages was compared, and its possible causes were explored. The results show that the developing speed of desertification from the late 1970s to the early 1990s is apparently slowed down, compared with that from the late 1950s to the late 1970s and there exists an obvious recovery trend at the second stage. The difference between the two stages accounts for severely over-reclaiming, over-grazing and unrestricted cutting during the first stage, which are the main causes of desertification development in the semi-arid steppe and arid desert steppe areas.
基金supported by National Natural Science Foundation of China(Grant No.71601123)MOE(Ministry of Education in China)Project of Humanities and Social Sciences(Grant No.15YJC910004)+3 种基金supported by National Natural Science Foundation of China(Grant No.11471277)the Research Grant Council of the Hong Kong Special Administration Region(Grant No.GRF14305014)supported by the State Key Program of National Natural Science Foundation of China(Grant No.71331006)the Major Research Plan of National Natural Science Foundation of China(Grant No.91546202)
文摘The double-threshold autoregressive conditional heteroscedastic(DTARCH) model is a useful tool to measure and forecast the mean and volatility of an asset return in a financial time series. The DTARCH model can handle situations wherein the conditional mean and conditional variance specifications are piecewise linear based on previous information. In practical applications, it is important to check whether the model has a double threshold for the conditional mean and conditional heteroscedastic variance. In this study, we develop a likelihood ratio test based on the estimated residual error for the hypothesis testing of DTARCH models. We first investigate DTARCH models with restrictions on parameters and propose the unrestricted and restricted weighted composite quantile regression(WCQR) estimation for the model parameters. These estimators can be used to construct the likelihood ratio-type test statistic. We establish the asymptotic results of the WCQR estimators and asymptotic distribution of the proposed test statistics. The finite sample performance of the proposed WCQR estimation and the test statistic is shown to be acceptable and promising using simulation studies. We use two real datasets derived from the Shanghai and Shenzhen Composite Indexes to illustrate the methodology.
基金This work was partially supported by grants from the National Natural Science Foundation of China (Nos.81670470 and 81600149)a grant from the Shan ghai Municipal Commissi on for Science and Tech nology (17140901600,18411953500 and 15JC1400201)a grant from National Key Research and Development Program (2016YFC0905100).
文摘This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/ licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
