176 research outputs found
Impulsivity in patients with obsessive-compulsive disorder: exploring the mediating effect of cognitive emotion regulation strategies and depressive symptoms
No full textBackgroundThe underlying mechanism of impulsivity in obsessive-compulsive disorder (OCD) patients is complex and still unclear. Previous studies have not thoroughly explored whether impulsivity in OCD patients is a result of the obsessive-compulsive symptoms themselves or other contributing factors. This study aimed to explore whether cognitive emotion regulation strategies and depressive symptoms mediate the relationship between the severity of obsessive-compulsive symptoms and impulsivity in a clinical population with OCD.MethodsThis was a case-control study that recruited 65 OCD patients (male/female=31/34) and 65 healthy controls (male/female =23/42), matched for age, gender, and education level. Demographic and clinical data were collected, and the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Beck Depression Inventory-II (BDI-II), Barratt Impulsiveness Scale-11 (BIS-11) and Cognitive Emotion Regulation Questionnaire (CERQ) were adopted.ResultsOCD patients scored higher on BIS-11 attentional and non-planning impulsiveness and total scores (all p < 0.05). On CERQ, OCD patients showed elevated maladaptive strategies (self-blame, rumination, catastrophizing, blaming others) and reduced adaptive strategies (positive reappraisal) (all p < 0.05). Attentional impulsiveness positively correlated with OCD severity, depression, and maladaptive strategies (all p < 0.05). Non-planning impulsiveness and BIS-11 total scores positively correlated with depression and negatively with adaptive strategies (all p < 0.05). After adjusting for age, gender, depression level, there was only a significant negative correlation between BIS-11 non-planning impulsiveness and CERQ maladaptive strategies (r = -0.28, p < 0.05). Mediation analysis revealed significant indirect effects of OCD severity on impulsivity via adaptive strategies/depression (β = 0.13, 95% CI: 0.03~0.24, p = 0.012) and via maladaptive strategies/depression (β = 0.09, 95% CI: 0.00~0.23, p = 0.042), but no significant direct or total effects.ConclusionsOCD symptom severity indirectly influences impulsivity through emotion regulation strategies and depressive symptoms, highlighting the need to target these mediators in clinical interventions
Analysis of Principal Structural Orientation of Trabecular Bone Using Quantitative Ultrasound
No full textQuantitative ultrasound (QUS) has been accepted widely as a non-invasive, economic, non-radioactive and portable modality for assessing bone heath status. This technology utilizes the basic physical mechanism of interaction between ultrasound wave and bone structure to provide mechanical and structural information of bone. Instead of only evaluating the quantity of bone like other traditional techniques such as duel energy X-ray absorptiometry (DXA), QUS is also capable of measuring the quality of bone such as anisotropy, microarchitecture and microfracture. This advantage of QUS is beneficial for treating the patient suffering from osteoporosis or other bone health deterioration, long term bed-rest patient and astronaut experiences low gravity environment. To improve the current QUS technology for bone mechanical properties assessment and fracture risk prediction, the focuses of this study are: 1) to develop a novel QUS measurement protocol to predict the principal structural orientation (PSO) of spherical trabecular bone model; 2) to use finite element analysis (FEA) to evaluate the mechanical properties in the PSO predicted by QUS; 3) to apply this novel QUS measurement on human calcaneus as an improved evaluation for the mechanical properties. It is shown that the PSO predicted by QUS is highly close to the PSO predicted by micro computed tomography (μCT), and the average angle difference is less than 5° using prediction of ultrasound velocity. The FEA simulation based on the μCT images showed the mechanical strength in the PSO predicted by QUS is significantly higher than the anatomical orientations and highly close to the value in longest vector of MIL tensor measured by μCT. By applying the same QUS measurement of PSO on bovine cubic bone samples and human calcaneus, the correlations between the QUS parameters and the mechanical and structural properties of trabecular bone were significantly improved (p<0.05), suggesting that such QUS measurement can be applied to human calcaneus evaluation and improves the reliability and accuracy for bone strength measurement and fracture risk assessment
Analysis of Principal Structural Orientation of Trabecular Bone Using Quantitative Ultrasound
No full textQuantitative ultrasound (QUS) has been accepted widely as a non-invasive, economic, non-radioactive and portable modality for assessing bone heath status. This technology utilizes the basic physical mechanism of interaction between ultrasound wave and bone structure to provide mechanical and structural information of bone. Instead of only evaluating the quantity of bone like other traditional techniques such as duel energy X-ray absorptiometry (DXA), QUS is also capable of measuring the quality of bone such as anisotropy, microarchitecture and microfracture. This advantage of QUS is beneficial for treating the patient suffering from osteoporosis or other bone health deterioration, long term bed-rest patient and astronaut experiences low gravity environment. To improve the current QUS technology for bone mechanical properties assessment and fracture risk prediction, the focuses of this study are: 1) to develop a novel QUS measurement protocol to predict the principal structural orientation (PSO) of spherical trabecular bone model; 2) to use finite element analysis (FEA) to evaluate the mechanical properties in the PSO predicted by QUS; 3) to apply this novel QUS measurement on human calcaneus as an improved evaluation for the mechanical properties. It is shown that the PSO predicted by QUS is highly close to the PSO predicted by micro computed tomography (µCT), and the average angle difference is less than 5° using prediction of ultrasound velocity. The FEA simulation based on the µCT images showed the mechanical strength in the PSO predicted by QUS is significantly higher than the anatomical orientations and highly close to the value in longest vector of MIL tensor measured by µCT. By applying the same QUS measurement of PSO on bovine cubic bone samples and human calcaneus, the correlations between the QUS parameters and the mechanical and structural properties of trabecular bone were significantly improved (p\u3c0.05), suggesting that such QUS measurement can be applied to human calcaneus evaluation and improves the reliability and accuracy for bone strength measurement and fracture risk assessment. | Quantitative ultrasound (QUS) has been accepted widely as a non-invasive, economic, non-radioactive and portable modality for assessing bone heath status. This technology utilizes the basic physical mechanism of interaction between ultrasound wave and bone structure to provide mechanical and structural information of bone. Instead of only evaluating the quantity of bone like other traditional techniques such as duel energy X-ray absorptiometry (DXA), QUS is also capable of measuring the quality of bone such as anisotropy, microarchitecture and microfracture. This advantage of QUS is beneficial for treating the patient suffering from osteoporosis or other bone health deterioration, long term bed-rest patient and astronaut experiences low gravity environment. To improve the current QUS technology for bone mechanical properties assessment and fracture risk prediction, the focuses of this study are: 1) to develop a novel QUS measurement protocol to predict the principal structural orientation (PSO) of spherical trabecular bone model; 2) to use finite element analysis (FEA) to evaluate the mechanical properties in the PSO predicted by QUS; 3) to apply this novel QUS measurement on human calcaneus as an improved evaluation for the mechanical properties. It is shown that the PSO predicted by QUS is highly close to the PSO predicted by micro computed tomography (µCT), and the average angle difference is less than 5° using prediction of ultrasound velocity. The FEA simulation based on the µCT images showed the mechanical strength in the PSO predicted by QUS is significantly higher than the anatomical orientations and highly close to the value in longest vector of MIL tensor measured by µCT. By applying the same QUS measurement of PSO on bovine cubic bone samples and human calcaneus, the correlations between the QUS parameters and the mechanical and structural properties of trabecular bone were significantly improved (p\u3c0.05), suggesting that such QUS measurement can be applied to human calcaneus evaluation and improves the reliability and accuracy for bone strength measurement and fracture risk assessment. | 129 page
Business output and business experience — Evidence from China's nongovernmental businesses
No full textWe study the application of the Solow growth model in China's non-governmental businesses and propose a reasonable modification for it. Our analysis indicates that business experience is closely tied to the output of China's non-governmental businesses. Our major findings include: (1) the business experience has little overall impact on the elasticity of output with respect to labour; (2) the business experience has a large impact on the elasticity of output with respect to capital and the elasticity increases as the business experience increases; (3) the adjusted Solow residual that reflects technological progress exhibits a negative relationship with the business experience, indicating that a newly established business tends to have higher technology content than others.
Instrumental Variable Quantile Estimation of Spatial Autoregressive Models
No full textWe propose an instrumental variable quantile regression (IVQR) estimator for spatial autoregressive (SAR) models. Like the GMM estimators of Lin and Lee (2006) and Kelejian and Prucha (2006), the IVQR estimator is robust against heteroscedasticity. Unlike the GMM estimators, the IVQR estimator is also robust against outliers and requires weaker moment conditions. More importantly, it allows us to characterize the heterogeneous impact of variables on different points (quantiles) of a response distribution. We derive the limiting distribution of the new estimator. Simulation results show that the new estimator performs well in finite samples at various quantile points. In the special case of median restriction, it outperforms the conventional QML estimator without taking into account of heteroscedasticity in the errors; it also outperforms the GMM estimators with or without considering the heteroscedasticity.Spatial Autoregressive Model, Quantile Regression, Instrumental Variable, Quasi Maximum Likelihood, GMM, Robustness
Instrumental Variable Quantile Estimation of Spatial Autoregressive Models
No full textWe propose an instrumental variable quantile regression (IVQR) estimator for spatial autoregressive (SAR) models. Like the GMM estimators of Lin and Lee (2006) and Kelejian and Prucha (2006), the IVQR estimator is robust against heteroscedasticity. Unlike the GMM estimators, the IVQR estimator is also robust against outliers and requires weaker moment conditions. More importantly, it allows us to characterize the heterogeneous impact of variables on different points (quantiles) of a response distribution. We derive the limiting distribution of the new estimator. Simulation results show that the new estimator performs well in finite samples at various quantile points. In the special case of median restriction, it outperforms the conventional QML estimator without taking into account of heteroscedasticity in the errors; it also outperforms the GMM estimators with or without considering the heteroscedasticity.Spatial Autoregressive Model; Quantile Regression; Instrumental Variable; Quasi Maximum Likelihood; GMM; Robustness.
Instrumental variable quantile estimation of spatial autoregressive models
No full textWe propose an instrumental variable quantile regression (IVQR) estimator for spatial autoregres-sive (SAR) models. Like the GMM estimators of Lin and Lee (2006) and Kelejian and Prucha (2006), the IVQR estimator is robust against heteroscedasticity. Unlike the GMM estimators, the IVQR es-timator is also robust against outliers and requires weaker moment conditions. More importantly, it allows us to characterize the heterogeneous impact of variables on different points (quantiles) of a response distribution. We derive the limiting distribution of the new estimator. Simulation results show that the new estimator performs well in finite samples at various quantile points. In the spe-cial case of median restriction, it outperforms the conventional QML estimator without taking into account of heteroscedasticity in the errors; it also outperforms the GMM estimators with or without considering the heteroscedasticity
Integrated transmission-reflection quantitative ultrasound noninvasive prediction of trabecular bone principal structural orientation validated with mechanical testing
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