Parameter transfer learning based on shallow visual geometry group network and its application in motor imagery classification / 生物医学工程学杂志

Transfer learning is provided with potential research value and application prospect in motor imagery electroencephalography (MI-EEG)-based brain-computer interface (BCI) rehabilitation system, and the source domain classification model and transfer strategy are the two important aspects that directly affect the performance and transfer efficiency of the target domain model. Therefore, we propose a parameter transfer learning method based on shallow visual geometry group network (PTL-sVGG). First, Pearson correlation coefficient is used to screen the subjects of the source domain, and the short-time Fourier transform is performed on the MI-EEG data of each selected subject to acquire the time-frequency spectrogram images (TFSI). Then, the architecture of VGG-16 is simplified and the block design is carried out, and the modified sVGG model is pre-trained with TFSI of source domain. Furthermore, a block-based frozen-fine-tuning transfer strategy is designed to quickly find and freeze the block with the greatest contribution to sVGG model, and the remaining blocks are fine-tuned by using TFSI of target subjects to obtain the target domain classification model. Extensive experiments are conducted based on public MI-EEG datasets, the average recognition rate and Kappa value of PTL-sVGG are 94.9% and 0.898, respectively. The results show that the subjects' optimization is beneficial to improve the model performance in source domain, and the block-based transfer strategy can enhance the transfer efficiency, realizing the rapid and effective transfer of model parameters across subjects on the datasets with different number of channels. It is beneficial to reduce the calibration time of BCI system, which promote the application of BCI technology in rehabilitation engineering.

Temporal patterns of dengue epidemics: The case of recent outbreaks in Kaohsiung

Objective To investigate whether major dengue outbreaks in the last two decades in Kaohsiung follow a precise temporal pattern. Methods Government daily lab-confirmed dengue case data from three major dengue outbreaks occurring during the last two decades in Kaohsiung in 2002, 2014 and 2015, is utilized to compute the corresponding weekly cumulative percentage of total case numbers. We divide each of the three time series data into two periods to examine the corresponding weekly cumulative percentages of case numbers for each period. Pearson's correlation coefficient was calculated to compare quantitatively the similarity between the temporal patterns of these three years. Results Three cutoff points produce the most interesting comparisons and the most different outcomes. Pearson's correlation coefficient indicates quantitative discrepancies in the similarity between temporal patterns of the three years when using different cutoff points. Conclusions Temporal patterns in 2002 and 2014 are comparatively more similar in early stage. The 2015 outbreak started late in the year, but ended more like the outbreak in 2014, both with record-breaking number of cases. The retrospective analysis shows that the temporal dynamics of dengue outbreaks in Kaohsiung can strongly vary from one year to another, making it difficult to identify any common predictor.

Temporal patterns of dengue epidemics: The case of recent outbreaks in Kaohsiung

OBJECTIVE@#To investigate whether major dengue outbreaks in the last two decades in Kaohsiung follow a precise temporal pattern.@*METHODS@#Government daily lab-confirmed dengue case data from three major dengue outbreaks occurring during the last two decades in Kaohsiung in 2002, 2014 and 2015, is utilized to compute the corresponding weekly cumulative percentage of total case numbers. We divide each of the three time series data into two periods to examine the corresponding weekly cumulative percentages of case numbers for each period. Pearson's correlation coefficient was calculated to compare quantitatively the similarity between the temporal patterns of these three years.@*RESULTS@#Three cutoff points produce the most interesting comparisons and the most different outcomes. Pearson's correlation coefficient indicates quantitative discrepancies in the similarity between temporal patterns of the three years when using different cutoff points.@*CONCLUSIONS@#Temporal patterns in 2002 and 2014 are comparatively more similar in early stage. The 2015 outbreak started late in the year, but ended more like the outbreak in 2014, both with record-breaking number of cases. The retrospective analysis shows that the temporal dynamics of dengue outbreaks in Kaohsiung can strongly vary from one year to another, making it difficult to identify any common predictor.

Evaluation of Reliability and Validity of the Louisville Instrument for Transplantation(LIFT) in Korean Population

PURPOSE: Composite tissue allotransplantation has emerged as a new therapeutic modality to reconstruct major tissue defects of the head, neck and extremities. A questionnaire-based instrument, the Louisville Instrument for Transplantation(LIFT), has been developed to objectively assess the risk-versus-benefit ratio for composite tissue allotransplantation procedures. The objective of this study is to assess if the LIFT is a useful, reliable and valid tool to apply to the Korean population. METHODS: Seventy-three medical students and 60 lay public completed the LIFT questionnaire(translated to Korean) over the period from February 2010 to April 2010. Internal consistency was assessed using Cronbach's alpha. Test-retest reliability was analyzed using Pearson's correlation coefficient. Construct validity was assessed by comparing Pearson's correlation coefficients between perceived improvements in quality of life and responses to risk tolerance questions concerning organ transplants. RESULTS: Measurements of the test-retest reliability showed that Pearson's correlation coefficients ranged from 0.241 to 0.902, and Cronbach's alphas ranged from 0.52 to 0.80 for medical students and from 0.63 to 0.83 for the lay public. Pearson's correlation coefficients showed significant correlations between perceived improvements in quality of life and responses to risk tolerance questions concerning organ transplants. Hand transplant showed a significant correlation in medical students. Foot, hand, two hands, larynx, partial face transplants showed significant correlations for the lay public. CONCLUSION: The applicability of the LIFT to the Korean population was found to be reliable and valid. The LIFT may serve as a useful tool for clinical application in the Korean population.

A simple method to assess freezing of gait in Parkinson's disease patients

Freezing of gait (FOG) can be assessed by clinical and instrumental methods. Clinical examination has the advantage of being available to most clinicians; however, it requires experience and may not reveal FOG even for cases confirmed by the medical history. Instrumental methods have an advantage in that they may be used for ambulatory monitoring. The aim of the present study was to describe and evaluate a new instrumental method based on a force sensitive resistor and Pearson's correlation coefficient (Pcc) for the assessment of FOG. Nine patients with Parkinson's disease in the "on" state walked through a corridor, passed through a doorway and made a U-turn. We analyzed 24 FOG episodes by computing the Pcc between one "regular/normal" step and the rest of the steps. The Pcc reached ±1 for "normal" locomotion, while correlation diminished due to the lack of periodicity during FOG episodes. Gait was assessed in parallel with video. FOG episodes determined from the video were all detected with the proposed method. The computed duration of the FOG episodes was compared with those estimated from the video. The method was sensitive to various types of freezing; although no differences due to different types of freezing were detected. The study showed that Pcc analysis permitted the computerized detection of FOG in a simple manner analogous to human visual judgment, and its automation may be useful in clinical practice to provide a record of the history of FOG.