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41.
《Statistics In Biopharmaceutical Research》2013,5(4):326-337
An important aspect of the drug evaluation process is to have an integrated benefit-risk assessment to determine, using some quantitative measures, whether the benefit outweighs the risk for the target population. Chuang-Stein et al. proposed a five-category random variable along with three global measures of benefit-risk assessment. Assuming the cell probabilities follow a multinomial distribution, we propose a Bayesian approach for the longitudinal assessment of benefit-risk using these three global measures and a new measure. A Dirichlet distribution is used as the natural conjugate prior for multinomial cell probabilities, and the posterior distributions of cell-probabilities are recursively derived as the data from multiple visits become available. In a more generalized approach, a power prior is used through the likelihood function to discount the information from previous visits, and, again, the posterior distributions of the cell-probabilities at multiple visits are derived. The estimates of the posterior means and credible intervals for the four global measures are derived, and the decision rules based on the credible intervals are applied for the assessment of the four global measures. Using two simulated datasets generated under two different scenarios—one where benefit outweighs risk and the other where benefit does not outweigh risk—the performances of the four measures are evaluated using a Markov chain Monte Carlo (MCMC) technique. We illustrate of the methodology using clinical trial data. 相似文献
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43.
Hyo Jong Lee Adrian Preda Judith M. Ford Daniel H. Mathalon David B. Keator Theo G.M. van Erp Jessica A. Turner Steven G. Potkin 《Journal of Korean medical science》2015,30(5):625-631
Previous fMRI studies of sensorimotor activation in schizophrenia have found in some cases hypoactivity, no difference, or hyperactivity when comparing patients with controls; similar disagreement exists in studies of motor laterality. In this multi-site fMRI study of a sensorimotor task in individuals with chronic schizophrenia and matched healthy controls, subjects responded with a right-handed finger press to an irregularly flashing visual checker board. The analysis includes eighty-five subjects with schizophrenia diagnosed according to the DSM-IV criteria and eighty-six healthy volunteer subjects. Voxel-wise statistical parametric maps were generated for each subject and analyzed for group differences; the percent Blood Oxygenation Level Dependent (BOLD) signal changes were also calculated over predefined anatomical regions of the primary sensory, motor, and visual cortex. Both healthy controls and subjects with schizophrenia showed strongly lateralized activation in the precentral gyrus, inferior frontal gyrus, and inferior parietal lobule, and strong activations in the visual cortex. There were no significant differences between subjects with schizophrenia and controls in this multi-site fMRI study. Furthermore, there was no significant difference in laterality found between healthy controls and schizophrenic subjects. This study can serve as a baseline measurement of schizophrenic dysfunction in other cognitive processes.
Graphical Abstract
相似文献44.
介绍一种基于模型的多因子降维方法(MB-MDR),并通过实例说明其分析流程及其在基因-基因/环境交互作用分析中的应用。结果显示该方法可用于原始样本量较小的资料研究,同时也能解决许多经典MDR方法的不足;与其他MDR扩展方法相比,在探索交互作用方面具有更高的统计效能,并已成功应用于膀胱癌、湿疹等研究。MB-MDR能够处理二元性状和数量性状,并可在模型中调整因子的边际效应和混杂因子,与其他非参数方法相比具有一定优势。因此MB-MDR在基因-基因/环境交互作用分析中具有较好的应用前景。 相似文献
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46.
Yan-Hao Huang Jeon-Hor Chen Yeun-Chung Chang Chiun-Sheng Huang Woo Kyung Moon Wen-Jia Kuo Kuan-Ju Lai Ruey-Feng Chang 《Journal of digital imaging》2013,26(4):731-739
This study aims to evaluate whether the distribution of vessels inside and adjacent to tumor region at three-dimensional (3-D) power Doppler ultrasonography (US) can be used for the differentiation of benign and malignant breast tumors. 3-D power Doppler US images of 113 solid breast masses (60 benign and 53 malignant) were used in this study. Blood vessels within and adjacent to tumor were estimated individually in 3-D power Doppler US images for differential diagnosis. Six features including volume of vessels, vascularity index, volume of tumor, vascularity index in tumor, vascularity index in normal tissue, and vascularity index in surrounding region of tumor within 2 cm were evaluated. Neural network was then used to classify tumors by using these vascular features. The receiver operating characteristic (ROC) curve analysis and Student’s t test were used to estimate the performance. All the six proposed vascular features are statistically significant (p < 0.001) for classifying the breast tumors as benign or malignant. The AZ (area under ROC curve) values for the classification result were 0.9138. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of the diagnosis performance based on all six proposed features were 82.30 (93/113), 86.79 (46/53), 78.33 (47/60), 77.97 (46/59), and 87.04 % (47/54), respectively. The p value of AZ values between the proposed method and conventional vascularity index method using z test was 0.04. 相似文献
47.
ObjectiveThe aim of this review was to synthesize the current understanding relating to the risks of lower body functional asymmetry with injury in athletic populations.MethodsAn iterative data mining and sampling approach was used to construct a search phrase from key words, which were used to identify studies within SPORTdiscus, Medline and Academic Search Complete databases. Additional references were sourced from the reference lists of these articles.ResultsAfter screening, 31 papers were reviewed, from an initial search identifying 302 possible studies. A total of 6228 participants were involved in the studies, of which soccer players were the most observed sporting demographic (n = 2171). Of the 31 studies reviewed eight found no statistical association between lower limb asymmetry and injury risk, 10 studies provided partial statistically significant evidence and a further 10 provided statistically significant statistical links.ConclusionOverall moderate to lower quality evidence for functional asymmetry as a risk factor for injury in sport was observed. While the possibility of a relationship between lower limb functional asymmetry and injury risk cannot be ruled out, further higher quality investigations, adopting standardised methodologies, is required. 相似文献
48.
《Journal of medical engineering & technology》2013,37(6-7):344-353
During the recording time of lung sound (LS) signals from the chest wall of a subject, there is always heart sound (HS) signal interfering with it. This obscures the features of lung sound signals and creates confusion on pathological states, if any, of the lungs. A novel method based on empirical mode decomposition (EMD) technique is proposed in this paper for reducing the undesired heart sound interference from the desired lung sound signals. In this, the mixed signal is split into several components. Some of these components contain larger proportions of interfering signals like heart sound, environmental noise etc. and are filtered out. Experiments have been conducted on simulated and real-time recorded mixed signals of heart sound and lung sound. The proposed method is found to be superior in terms of time domain, frequency domain, and time–frequency domain representations and also in listening test performed by pulmonologist. 相似文献
49.
《Sleep medicine》2021
Objective/BackgroundThe aim of this study was to examine the relationship between overnight consolidation of implicit statistical learning with spindle frequency EEG activity and slow frequency delta power during non-rapid eye movement (NREM) sleep in obstructive sleep apnea (OSA).Patients/MethodsForty-seven OSA participants completed the experiment. Prior to sleep, participants performed a reaction time cover task containing hidden patterns of pictures, about which participants were not informed. After the familiarisation phase, participants underwent overnight polysomnography. 24 h after the familiarisation phase, participants performed a test phase to assess their learning of the hidden patterns, expressed as a percentage of the number of correctly identified patterns. Spindle frequency activity (SFA) and delta power (0.5–4.5 Hz), were quantified from NREM electroencephalography. Associations between statistical learning and sleep EEG, and OSA severity measures were examined.ResultsSFA in NREM sleep in frontal and central brain regions was positively correlated with statistical learning scores (r = 0.41 to 0.31, p = 0.006 to 0.044). In multiple regression, greater SFA and longer sleep onset latency were significant predictors of better statistical learning performance. Delta power and OSA severity were not significantly correlated with statistical learning.ConclusionsThese findings suggest spindle activity may serve as a marker of statistical learning capability in OSA. This work provides novel insight into how altered sleep physiology relates to consolidation of implicitly learnt information in patients with moderate to severe OSA. 相似文献
50.
F. Dall'Acqua G. Cristina-Souza A.C. Santos-Mariano R. Bertuzzi C. Rodacki A.E. Lima-Silva 《Brazilian journal of medical and biological research》2021,54(4)
The main movements of artistic swimming demand various physical capacities such as flexibility, strength, power, and muscular endurance. The use of ergogenic resources to potentialize performance in this sport, however, is underexplored and deserves investigation. In the present study, we tested whether caffeine ingestion would improve the execution of movements that are essential in a typical figure competition or routines in artistic swimming (i.e., amplitude in the Ariana, height in the Boost and Barracuda, and time maintained in the Stationary Scull techniques). Sixteen experienced female athlete artistic swimmers (17.4±3.2 years of age, 5.6±2.8 years of artistic swimming practice) performed several movements of artistic swimming after having ingested a capsule containing caffeine (5 mg/kg body mass) or cellulose (placebo). Compared to the placebo, caffeine improved latero-lateral amplitude during the Ariana (P=0.035), the height of the Boost and Barracuda (P=0.028 and 0.009), and maintained duration in Stationary Sculling (P=0.012). Bayes factor analysis, however, indicated substantial evidence of a positive effect of caffeine only on the Barracuda and Stationary Scull techniques. These findings indicated that caffeine improved performance during specific artistic swimming movements. Coaches and athletes should consider caffeine ingestion in their supplementation plans. 相似文献