2,226 research outputs found
Bayesian Inference on Brain-Computer Interfaces via GLASS
Brain-computer interfaces (BCIs), particularly the P300 BCI, facilitate
direct communication between the brain and computers. The fundamental
statistical problem in P300 BCIs lies in classifying target and non-target
stimuli based on electroencephalogram (EEG) signals. However, the low
signal-to-noise ratio (SNR) and complex spatial/temporal correlations of EEG
signals present challenges in modeling and computation, especially for
individuals with severe physical disabilities-BCI's primary users. To address
these challenges, we introduce a novel Gaussian Latent channel model with
Sparse time-varying effects (GLASS) under a fully Bayesian framework. GLASS is
built upon a constrained multinomial logistic regression particularly designed
for the imbalanced target and non-target stimuli. The novel latent channel
decomposition efficiently alleviates strong spatial correlations between EEG
channels, while the soft-thresholded Gaussian process (STGP) prior ensures
sparse and smooth time-varying effects. We demonstrate GLASS substantially
improves BCI's performance in participants with amyotrophic lateral sclerosis
(ALS) and identifies important EEG channels (PO8, Oz, PO7, and Pz) in parietal
and occipital regions that align with existing literature. For broader
accessibility, we develop an efficient gradient-based variational inference
(GBVI) algorithm for posterior computation and provide a user-friendly Python
module available at https://github.com/BangyaoZhao/GLASS.Comment: 32 pages, 5 figure
Characterizing the temporally stable structure of community evolution in intra-urban origin-destination networks
Intra-urban origin-destination (OD) network communities evolve throughout the
day, indicating changing groups of closely connected regions. Under this
variation, groups of regions with high consistency of community affiliation
characterize the temporally stable structure of the evolution process, aiding
in comprehending urban dynamics. However, how to quantify this consistency and
identify these groups are open questions. In this study, we introduce the
consensus OD network to quantify the consistency of community affiliation among
regions. Furthermore, the temporally stable community decomposition method is
proposed to identify groups of regions with high internal and low external
consistency (named "stable groups"), where each group consists of temporally
stable cores and attaching peripheries. Wuhan taxi data is used to verify our
methods. On the hourly time scale, eleven stable groups containing 82.9% of
regions are identified. This high percentage suggests that dynamic communities
can be well organized via cores. Moreover, stable groups are spatially closed
and more likely to distribute within a single district and separated by water
bodies. Cores exhibit higher POI entropy and more healthcare and shopping
services than peripheries. Our methods and empirical findings contribute to
some practical issues, such as urban area division, polycentric evaluation and
construction, and infectious disease control
Cough Test during Tension-Free Vaginal Tape Procedure in Preventing Postoperative Urinary Retention
Objective. To discuss the practical value of the cough test during the tension-free vaginal tape (TVT) procedure. Methods. In the first group, 41 patients of female stress incontinence received TVT operations which were performed according to the Ulmsten’s method strictly, only that the stress of tape was adjusted in light of the cough test. In the second group, 44 patients of female stress incontinence received TVT operations in which the tape was put under the urethral tract without stress, not adjusted by cough test. Results. The cure rate was 38/41 (92.6%) in the cough test group and 41/44 (93.1%) in the noncough test group; detrusor pressure-uroflow study indicated that there were 11 cases in the obstruction zone in the cough test group while only 3 cases were in the obstruction zone in the noncough test group; 4 cases of urinary retention and 5 cases of voiding dysfunction were found in the cough test group, while difficulties of urination were not found in the non-cough test group. Conclusion. Adjusting the tape stress in accordance with the cough test during the TVT can increase the opportunity of urinary retention or difficulty of urination after operation. So there is no benefit of the cough test during tension-free vaginal tape procedure in preventing post-operative urinary retention
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