Interhemispheric theta coherence in the hippocampus for successful object-location memory in human intracranial encephalography.

Our knowledge concerning visual-spatial memory related phase synchronization within the ipsilateral hippocampus or between contralateral hippocampi during memory encoding in humans is currently limited. The present study examines the relationship between phase synchronization within the hippocampus and memory performance during virtual navigation in an object-location memory navigation task using intracranial depth electrodes in human subjects. Specifically, we focus on the phase synchronization ratio between periods when the target object was in and out of visual focus. Our findings indicate that there is a significant relationship between this phase synchronization ratio and object-location memory performance in the theta band (p = 0.015, R = -0.71), but not in the delta or alpha bands. Importantly, this theta coherence has a significant linear relationship with memory performance between contralateral hippocampus electrode pairs (p = 0.006, R = -0.77), but not ipsilateral electrode pairs (p = 0.79, R = -0.09). In addition, this theta coherence has a significant linear relationship with memory performance during stationary periods (p = 0.002, R = -0.82), but not movement periods (p = 0.10, R = -0.51). These findings suggest that, during navigation, interhemispheric hippocampal theta coherence when stationary and focusing on the target object may be a critical determinant of successful object-location memory.

Prediction of treatment outcome using MRI radiomics and machine learning in oropharyngeal cancer patients after surgical treatment.

OBJECTIVES: In this study, we aimed to analyze preoperative MRI images of oropharyngeal cancer patients who underwent surgical treatment, extracted radiomics features, and constructed a disease recurrence and death prediction model using radiomics features and machine-learning techniques. MATERIALS AND METHODS: A total of 157 patients participated in this study, and 107 stable radiomics features were selected and used for constructing a predictive model. RESULTS: The performance of the combined model (clinical and radiomics) yielded the following results: AUC of 0.786, accuracy of 0.854, precision of 0.429, recall of 0.500, and f1 score of 0.462. The combined model showed better performance than either the clinical and radiomics only models for predicting disease recurrence. For predicting death, the combined model performance has an AUC of 0.841, accuracy of 0.771, precision of 0.308, recall of 0.667, and f1 score of 0.421. The combined model showed superior performance over the predictive model using only clinical variables. A Cox proportional hazard model using the combined variables for predicting patient death yielded a c-index value that was significantly better than that of the model including only clinical variables. CONCLUSIONS: A predictive model using clinical variables and MRI radiomics features showed excellent performance in predicting disease recurrence and death in oropharyngeal cancer patients. In the future, a multicenter study is necessary to verify the model's performance and confirm its clinical usefulness.

The Role of Charge Balance and Excited State Levels on Device Performance of Exciplex-based Phosphorescent Organic Light Emitting Diodes.

The design of novel exciplex-forming co-host materials provides new opportunities to achieve high device performance of organic light emitting diodes (OLEDs), including high efficiency, low driving voltage and low efficiency roll-off. Here, we report a comprehensive study of exciplex-forming co-host system in OLEDs including the change of co-host materials, mixing composition of exciplex in the device to improve the performance. We investigate various exciplex systems using 5-(3-4,6-diphenyl-1,3,5-triazin-2-yl)phenyl-3,9-diphenyl-9H-carbazole, 5-(3-4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9-phenyl-9H-3,9'-bicarbazole, and 2-(3-(6,9-diphenyl-9H-carbazol-4-yl)phenyl)-4-phenylbenzo[4,5]thieno[3,2-d]pyrimidine, as electron transporting (ET: electron acceptor) hosts and 9,9'-dipenyl-9H, 9'H-3,3'-bicarbazole and 9-([1,1'-biphenyl]-4-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole as hole transporting (HT: electron donor) hosts. As a result, a very high current efficiency of 105.1 cd/A at 103 cd/m2 and an extremely long device lifetime of 739 hrs (t95: time after 5% decrease of luminance) are achieved which is one of the best performance in OLEDs. Systematic approach, controlling mixing ratio of HT to ET host materials is suggested to select the component of two host system using energy band matching and charge balance optimization method. Furthermore, our analysis on exciton stability also reveal that lifetime of OLEDs have close relationship with two parameters; singlet energy level difference of HT and ET host and difference of singlet and triplet energy level in exciplex.