Pub Date : 2012-07-05DOI: 10.1109/QOMEX.2012.6263859
Chao Wang, X. Mou, Lei Zhang
Rate and distortion models (R-D models) are important for current image/video encoders. They can help encoders to find the best encoding parameters for improving encoding performance quickly and effectively. However, most of the existing R-D models are based on mean square error (MSE). For the purpose of achieving better perceptual quality in encoding, the R-D models based on perceptual distortion measurement are involuntarily needed. In this paper, we proposed a perceptual quality based R-D model for lossy image/video encoding. The experimental results show that, the proposed model can accurately describe the R-D characteristics of the sources in the context of perceptual distortion, both for whole frames and the areas inside frame.
{"title":"A perceptual quality based rate distortion model","authors":"Chao Wang, X. Mou, Lei Zhang","doi":"10.1109/QOMEX.2012.6263859","DOIUrl":"https://doi.org/10.1109/QOMEX.2012.6263859","url":null,"abstract":"Rate and distortion models (R-D models) are important for current image/video encoders. They can help encoders to find the best encoding parameters for improving encoding performance quickly and effectively. However, most of the existing R-D models are based on mean square error (MSE). For the purpose of achieving better perceptual quality in encoding, the R-D models based on perceptual distortion measurement are involuntarily needed. In this paper, we proposed a perceptual quality based R-D model for lossy image/video encoding. The experimental results show that, the proposed model can accurately describe the R-D characteristics of the sources in the context of perceptual distortion, both for whole frames and the areas inside frame.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"111 1","pages":"74-79"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73304813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many subjective assessment methods for video quality have been standardized. Although the performance of individual subjective assessment methods of 2D video quality has been studied to compare their stability, the performance per subjective assessment method for stereoscopic 3D video quality has not been sufficiently studied. To compare this performance, we conducted subjective quality assessments of 3D video using the double stimulus continuous quality-scale (DSCQS), absolute category rating (ACR), and degradation category rating (DCR) methods. As a result, the Pearson's and Spearman's rank correlations between two of the four methods (i.e., DSCQS, ACR, DCR, and ACR with hidden reference (ACR-HR)) were high. In terms of stability, the DCR method performed better than the others. However, in terms of both stability and assessment time, we found that the ACR method was most effective.
{"title":"Performance comparison of subjective assessment methods for 3D video quality","authors":"Taichi Kawano, Kazuhisa Yamagishi, Takanori Hayashi","doi":"10.1109/QoMEX.2012.6263833","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263833","url":null,"abstract":"Many subjective assessment methods for video quality have been standardized. Although the performance of individual subjective assessment methods of 2D video quality has been studied to compare their stability, the performance per subjective assessment method for stereoscopic 3D video quality has not been sufficiently studied. To compare this performance, we conducted subjective quality assessments of 3D video using the double stimulus continuous quality-scale (DSCQS), absolute category rating (ACR), and degradation category rating (DCR) methods. As a result, the Pearson's and Spearman's rank correlations between two of the four methods (i.e., DSCQS, ACR, DCR, and ACR with hidden reference (ACR-HR)) were high. In terms of stability, the DCR method performed better than the others. However, in terms of both stability and assessment time, we found that the ACR method was most effective.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"118 1","pages":"218-223"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75773142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QoMEX.2012.6263849
T. Hossfeld, S. Egger, R. Schatz, M. Fiedler, Kathrin Masuch, C. Lorentzen
End user quality perception in the context of Internet applications is often characterized by waiting times before service consumption as well as interruptions during service consumption. In particular in case of bad network conditions, network and service providers have to trade off between these two impairment types, i.e. between the devil and the deep blue sea. In this paper we investigate this tradeoff in order to guide the design and development of Internet applications and network management approaches. The contribution of this paper is twofold. Firstly, we quantify the impact of initial delays on the user perceived Quality of Experience (QoE) for different application scenarios by means of subjective laboratory and crowdsourcing studies. We show that QoE for a given waiting time strongly depends on the concrete application at hand but that rating diversity remains fairly application-invariant. Secondly, using the example of YouTube video streaming we compare the influence of initial delays and interruptions (stallings) during watching. Our results demonstrate that users are extremely sensitive to interruptions and that services should be designed accordingly e.g. by increasing initial delay for prebuffering to overcome lack of resources.
{"title":"Initial delay vs. interruptions: Between the devil and the deep blue sea","authors":"T. Hossfeld, S. Egger, R. Schatz, M. Fiedler, Kathrin Masuch, C. Lorentzen","doi":"10.1109/QoMEX.2012.6263849","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263849","url":null,"abstract":"End user quality perception in the context of Internet applications is often characterized by waiting times before service consumption as well as interruptions during service consumption. In particular in case of bad network conditions, network and service providers have to trade off between these two impairment types, i.e. between the devil and the deep blue sea. In this paper we investigate this tradeoff in order to guide the design and development of Internet applications and network management approaches. The contribution of this paper is twofold. Firstly, we quantify the impact of initial delays on the user perceived Quality of Experience (QoE) for different application scenarios by means of subjective laboratory and crowdsourcing studies. We show that QoE for a given waiting time strongly depends on the concrete application at hand but that rating diversity remains fairly application-invariant. Secondly, using the example of YouTube video streaming we compare the influence of initial delays and interruptions (stallings) during watching. Our results demonstrate that users are extremely sensitive to interruptions and that services should be designed accordingly e.g. by increasing initial delay for prebuffering to overcome lack of resources.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"65 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80204582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QOMEX.2012.6263843
Xiguang Zheng, C. Ritz
This paper presents a new framework for compression and transmission of simultaneously occurring audio objects through packet loss channels in order to maintain user Quality of Experience (QoE). The audio objects are compressed into two mono mixtures, by exploiting sparsity of multichannel audio signals to identify the two most dominant time-frequency components in terms of an energy measure. These mixtures are further compressed using the MP3 audio codec, with the optimised transmission model selected from several channel coding models based on the Forward Error Correction (FEC) and Multiple Description Coding (MDC) packet loss protection techniques. Audio objects can be recovered robustly from any received description(s) allowing real-time selective reproduction at the listeners' end. Results from spectral distortion measurements indicate the proposed scheme maintains the perceptual quality of the audio objects across a wide variety of packet loss conditions.
{"title":"Packet loss protection for interactive audio object rendering: A multiple description approach","authors":"Xiguang Zheng, C. Ritz","doi":"10.1109/QOMEX.2012.6263843","DOIUrl":"https://doi.org/10.1109/QOMEX.2012.6263843","url":null,"abstract":"This paper presents a new framework for compression and transmission of simultaneously occurring audio objects through packet loss channels in order to maintain user Quality of Experience (QoE). The audio objects are compressed into two mono mixtures, by exploiting sparsity of multichannel audio signals to identify the two most dominant time-frequency components in terms of an energy measure. These mixtures are further compressed using the MP3 audio codec, with the optimised transmission model selected from several channel coding models based on the Forward Error Correction (FEC) and Multiple Description Coding (MDC) packet loss protection techniques. Audio objects can be recovered robustly from any received description(s) allowing real-time selective reproduction at the listeners' end. Results from spectral distortion measurements indicate the proposed scheme maintains the perceptual quality of the audio objects across a wide variety of packet loss conditions.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"8 1","pages":"68-73"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84213159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QoMEX.2012.6263852
Blazej Lewcio, S. Möller
Video calls performed in heterogeneous mobile networks are affected by time-varying quality changes. Packet loss or transmission adaptation by network handover, bit rate switching, or codec changeover, are the potential results of user mobility. In order to optimize the quality under these circumstances, quality monitoring plays an essential role to improve user experience in future mobile networks. However, the existing quality prediction models have not been fully validated for video telephony in future networks. In this paper, we analyse the applicability of speech, video, and call quality prediction models for video telephony in heterogeneous wireless networks. We focus on user perception of changing transmission quality. We show how accurately the quality of video calls in mobile networks can be predicted with the existing approaches, and we disclose the major limitations of the individual models. Thus, this paper contributes to the monitoring of video call quality in future mobile networks.
{"title":"Predicting video call quality in future mobile networks","authors":"Blazej Lewcio, S. Möller","doi":"10.1109/QoMEX.2012.6263852","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263852","url":null,"abstract":"Video calls performed in heterogeneous mobile networks are affected by time-varying quality changes. Packet loss or transmission adaptation by network handover, bit rate switching, or codec changeover, are the potential results of user mobility. In order to optimize the quality under these circumstances, quality monitoring plays an essential role to improve user experience in future mobile networks. However, the existing quality prediction models have not been fully validated for video telephony in future networks. In this paper, we analyse the applicability of speech, video, and call quality prediction models for video telephony in heterogeneous wireless networks. We focus on user perception of changing transmission quality. We show how accurately the quality of video calls in mobile networks can be predicted with the existing approaches, and we disclose the major limitations of the individual models. Thus, this paper contributes to the monitoring of video call quality in future mobile networks.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"30 1","pages":"140-145"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86734935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QoMEX.2012.6263856
Petko N. Petkov, H. Helgason, W. Kleijn
A non-intrusive quality predictor constitutes a mapping from signal features to a (typically one dimensional) representation of the perceived quality. Assuming that the regression model performing the mapping is suited to the data, the performance of the predictor largely depends on how well the parameters of this regression model can be inferred from the training data. In situations where the training data is scarce, model performance is degraded due to over-fitting. The effects of over-fitting can be mitigated by feature selection but the model performance remains low due to the insufficiently representative training data. The objective we pursue is to enhance the performance of a quality predictor by augmenting the feature set with the output of a pre-trained quality predictor. This approach introduces an implicit dependence of the regression model parameters on a larger amount of training data. In view of the increasing usage of speech signals with higher bandwidth, and the dearth of training data for such signals, an augmentation of particular interest is that of a wide-band feature set with a narrow-band quality prediction. Experimental results for additive noise and non-linear distortions encountered in hearing aids, using quality labels from an intrusive quality predictor, illustrate the performance enhancement capabilities of the proposed approach.
{"title":"Feature set augmentation for enhancing the performance of a non-intrusive quality predictor","authors":"Petko N. Petkov, H. Helgason, W. Kleijn","doi":"10.1109/QoMEX.2012.6263856","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263856","url":null,"abstract":"A non-intrusive quality predictor constitutes a mapping from signal features to a (typically one dimensional) representation of the perceived quality. Assuming that the regression model performing the mapping is suited to the data, the performance of the predictor largely depends on how well the parameters of this regression model can be inferred from the training data. In situations where the training data is scarce, model performance is degraded due to over-fitting. The effects of over-fitting can be mitigated by feature selection but the model performance remains low due to the insufficiently representative training data. The objective we pursue is to enhance the performance of a quality predictor by augmenting the feature set with the output of a pre-trained quality predictor. This approach introduces an implicit dependence of the regression model parameters on a larger amount of training data. In view of the increasing usage of speech signals with higher bandwidth, and the dearth of training data for such signals, an augmentation of particular interest is that of a wide-band feature set with a narrow-band quality prediction. Experimental results for additive noise and non-linear distortions encountered in hearing aids, using quality labels from an intrusive quality predictor, illustrate the performance enhancement capabilities of the proposed approach.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"19 1","pages":"121-126"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84445760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QoMEX.2012.6263854
Philippe Hanhart, F. D. Simone, T. Ebrahimi
When a stereo pair is formed from a decoded view and a synthesized view, it is unclear how the overall quality of the stereo pair should be assessed through objective quality metrics. In this paper, this problem is addressed considering a 3D video represented in the format of multiview video plus depth. The performance of different PSNR-based metrics are analyzed in terms of correlation with subjective perception of video quality. A set of subjective data collected through formal subjective evaluation tests is used as benchmark. Results show that, among the considered metrics, the PSNR of the decoded view has the highest correlation with the perceived quality while the PSNR of the synthesized view has the lowest correlation.
{"title":"Quality assessment of asymmetric stereo pair formed from decoded and synthesized views","authors":"Philippe Hanhart, F. D. Simone, T. Ebrahimi","doi":"10.1109/QoMEX.2012.6263854","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263854","url":null,"abstract":"When a stereo pair is formed from a decoded view and a synthesized view, it is unclear how the overall quality of the stereo pair should be assessed through objective quality metrics. In this paper, this problem is addressed considering a 3D video represented in the format of multiview video plus depth. The performance of different PSNR-based metrics are analyzed in terms of correlation with subjective perception of video quality. A set of subjective data collected through formal subjective evaluation tests is used as benchmark. Results show that, among the considered metrics, the PSNR of the decoded view has the highest correlation with the perceived quality while the PSNR of the synthesized view has the lowest correlation.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"18 1","pages":"236-241"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79057349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QoMEX.2012.6263853
Selim Ickin, L. Janowski, K. Wac, M. Fiedler
Evaluating video Quality of Experience (QoE) on a mobile phone has not yet been studied much. It is common that the data collected through user studies in mobile platform involves high fluctuation of user ratings without obvious reasons related to variation in network level. User disparity, user's various intermediate or previous experiences, video bitrate, and the objective measure of criticality are a few of the reasons that need to be identified with a well-designed user experiment. We present an experiment procedure to understand better the perceived quality of video in mobile platform. First, we investigate the reliability of the data, and identify unreliable users. Then, we investigate the psychological influence factors of previous experiences on the recent perceived quality known as the memory effect, and the influence of the bitrate on the time it takes for users to react and evaluate the video quality, i.e., user response time.
{"title":"Studying the challenges in assessing the perceived quality of mobile-phone based video","authors":"Selim Ickin, L. Janowski, K. Wac, M. Fiedler","doi":"10.1109/QoMEX.2012.6263853","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263853","url":null,"abstract":"Evaluating video Quality of Experience (QoE) on a mobile phone has not yet been studied much. It is common that the data collected through user studies in mobile platform involves high fluctuation of user ratings without obvious reasons related to variation in network level. User disparity, user's various intermediate or previous experiences, video bitrate, and the objective measure of criticality are a few of the reasons that need to be identified with a well-designed user experiment. We present an experiment procedure to understand better the perceived quality of video in mobile platform. First, we investigate the reliability of the data, and identify unreliable users. Then, we investigate the psychological influence factors of previous experiences on the recent perceived quality known as the memory effect, and the influence of the bitrate on the time it takes for users to react and evaluate the video quality, i.e., user response time.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"35 1","pages":"164-169"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84977789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QoMEX.2012.6263846
A. Sackl, S. Egger, Patrick Zwickl, P. Reichl
Studying the connection between QoE and QoS and its implications for network and content providers has yielded a couple of well-established experimental approaches. However, research in this field has mainly neglected economical aspects of user trials. This paper describes and evaluates an extended experimental setup to investigate willingness-to-pay for enhanced video quality inferred from network quality parameters. The results confirm that our realistic setup provides valid results indicating the suitability for upcoming studies bringing economical aspects and QoE together.
{"title":"The QoE alchemy: Turning quality into money. Experiences with a refined methodology for the evaluation of willingness-to-pay for service quality","authors":"A. Sackl, S. Egger, Patrick Zwickl, P. Reichl","doi":"10.1109/QoMEX.2012.6263846","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263846","url":null,"abstract":"Studying the connection between QoE and QoS and its implications for network and content providers has yielded a couple of well-established experimental approaches. However, research in this field has mainly neglected economical aspects of user trials. This paper describes and evaluates an extended experimental setup to investigate willingness-to-pay for enhanced video quality inferred from network quality parameters. The results confirm that our realistic setup provides valid results indicating the suitability for upcoming studies bringing economical aspects and QoE together.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"77 1","pages":"170-175"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86150997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-07-05DOI: 10.1109/QoMEX.2012.6263874
T. Falk, Yael Pomerantz, K. Laghari, S. Möller, T. Chau
Image preference is a subjective factor which plays an important role in Quality-of-Experience (QoE) modelling. Traditionally, preference characterization has been quantified via questionnaires or subjective evaluations. Current advances in neurophysiological signal acquisition, however, have allowed for such “non-measurable” subjective parameters to be quantified objectively. In this pilot study, we explore the use of neurophysiological signals as correlates of image preference characterization. Experiments with seven participants have shown promising results and mental states associated with preferred and non-preferred images, as well as baseline neutral state could be classified with above-chance levels.
{"title":"Preliminary findings on image preference characterization based on neurophysiological signal analysis: Towards objective QoE modeling","authors":"T. Falk, Yael Pomerantz, K. Laghari, S. Möller, T. Chau","doi":"10.1109/QoMEX.2012.6263874","DOIUrl":"https://doi.org/10.1109/QoMEX.2012.6263874","url":null,"abstract":"Image preference is a subjective factor which plays an important role in Quality-of-Experience (QoE) modelling. Traditionally, preference characterization has been quantified via questionnaires or subjective evaluations. Current advances in neurophysiological signal acquisition, however, have allowed for such “non-measurable” subjective parameters to be quantified objectively. In this pilot study, we explore the use of neurophysiological signals as correlates of image preference characterization. Experiments with seven participants have shown promising results and mental states associated with preferred and non-preferred images, as well as baseline neutral state could be classified with above-chance levels.","PeriodicalId":6303,"journal":{"name":"2012 Fourth International Workshop on Quality of Multimedia Experience","volume":"24 1","pages":"146-147"},"PeriodicalIF":0.0,"publicationDate":"2012-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86172739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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