106 research outputs found
A vicious cycle along busy bus corridors and how to abate it
We unveil that a previously-unreported vicious cycle can be created when bus
queues form at curbside stops along a corridor. Buses caught in this cycle
exhibit growing variation in headways as they travel from stop to stop. Bus
(and patron) delays accumulate in like fashion and can grow large on long, busy
corridors. We show that this damaging cycle can be abated in simple ways.
Present solutions entail holding buses at a corridor entrance and releasing
them as per various strategies proposed in the literature. We introduce a
modest variant to the simplest of these strategies. It releases buses at
headways that are slightly less than, or equal to, the scheduled values. It
turns out that periodically releasing buses at slightly smaller headways can
substantially reduce bus delays caused by holding so that benefits can more
readily outweigh costs in corridors that contain a sufficient number of serial
bus stops. The simple variant is shown to perform about as well as, or better
than, other bus-holding strategies in terms of saving delays, and is more
effective than other strategies in regularizing bus headways. We also show that
grouping buses from across multiple lines and holding them by group can be
effective when patrons have the flexibility to choose buses from across all
lines in a group. Findings come by formulating select models of bus-corridor
dynamics and using these to simulate part of the Bus Rapid Transit corridor in
Guangzhou, China
MLA-BIN: Model-level Attention and Batch-instance Style Normalization for Domain Generalization of Federated Learning on Medical Image Segmentation
The privacy protection mechanism of federated learning (FL) offers an
effective solution for cross-center medical collaboration and data sharing. In
multi-site medical image segmentation, each medical site serves as a client of
FL, and its data naturally forms a domain. FL supplies the possibility to
improve the performance of seen domains model. However, there is a problem of
domain generalization (DG) in the actual de-ployment, that is, the performance
of the model trained by FL in unseen domains will decrease. Hence, MLA-BIN is
proposed to solve the DG of FL in this study. Specifically, the model-level
attention module (MLA) and batch-instance style normalization (BIN) block were
designed. The MLA represents the unseen domain as a linear combination of seen
domain models. The atten-tion mechanism is introduced for the weighting
coefficient to obtain the optimal coefficient ac-cording to the similarity of
inter-domain data features. MLA enables the global model to gen-eralize to
unseen domain. In the BIN block, batch normalization (BN) and instance
normalization (IN) are combined to perform the shallow layers of the
segmentation network for style normali-zation, solving the influence of
inter-domain image style differences on DG. The extensive experimental results
of two medical image seg-mentation tasks demonstrate that the proposed MLA-BIN
outperforms state-of-the-art methods.Comment: 9 pages, 8 figures, 2 table
Improving the critical speeds of high-speed trains using magnetorheological technology
With the rapid development of high-speed railways, vibration control for maintaining stability, passenger comfort, and safety has become an important area of research. In order to investigate the mechanism of train vibration, the critical speeds of various DOFs with respect to suspension stiffness and damping are first calculated and analyzed based on its dynamic equations. Then, the sensitivity of the critical speed is studied by analyzing the influence of different suspension parameters. On the basis of these analyses, a conclusion is drawn that secondary lateral damping is the most sensitive suspension damper. Subsequently, the secondary lateral dampers are replaced with magnetorheological fluid (MRF) dampers. Finally, a high-speed train model with MRF dampers is simulated by a combined ADAMS and MATLAB simulation and tested in a roller rig test platform to investigate the mechanism of how the MRF damper affects the train\u27s stability and critical speed. The results show that the semi-active suspension installed with MRF dampers substantially improves the stability and critical speed of the train
A Water-Soluble Polysaccharide from the Fruit Bodies of Bulgaria inquinans (Fries) and Its Anti-Malarial Activity
A water-soluble polysaccharide (BIWS-4b) was purified from the fruit bodies of Bulgaria inquinans (Fries). It is composed of mannose (27.2%), glucose (15.5%) and galactose (57.3%). Its molecular weight was estimated to be 7.4 kDa (polydispersity index, Mw/Mn: 1.35). Structural analyses indicated that BIWS-4b mainly contains (1 → 6)-linked, (1 → 5)-linked and (1 → 5,6)-linked β-Galf units; (1 → 4)-linked and non-reducing terminal β-Glcp units; and (1 → 2)-linked, (1 → 6)-linked, (1 → 2,6)-linked and non-reducing terminal α-Manp units. When examined by the 4-day method and in a prophylactic assay in mice, BIWS-4b exhibited markedly suppressive activity against malaria while enhancing the activity of artesunate. Immunological tests indicated that BIWS-4b significantly enhanced macrophage phagocytosis and splenic lymphocyte proliferation in malaria-bearing mice and normal mice. The anti-malarial activity of BIWS-4b might be intermediated by enhancing immune competence and restoring artesunate-suppressed immune function. Thus, BIWS-4b is a potential adjuvant of anti-malaria drugs
A Robust Deep Learning Method with Uncertainty Estimation for the Pathological Classification of Renal Cell Carcinoma based on CT Images
Objectives To develop and validate a deep learning-based diagnostic model
incorporating uncertainty estimation so as to facilitate radiologists in the
preoperative differentiation of the pathological subtypes of renal cell
carcinoma (RCC) based on CT images. Methods Data from 668 consecutive patients,
pathologically proven RCC, were retrospectively collected from Center 1. By
using five-fold cross-validation, a deep learning model incorporating
uncertainty estimation was developed to classify RCC subtypes into clear cell
RCC (ccRCC), papillary RCC (pRCC), and chromophobe RCC (chRCC). An external
validation set of 78 patients from Center 2 further evaluated the model's
performance. Results In the five-fold cross-validation, the model's area under
the receiver operating characteristic curve (AUC) for the classification of
ccRCC, pRCC, and chRCC was 0.868 (95% CI: 0.826-0.923), 0.846 (95% CI:
0.812-0.886), and 0.839 (95% CI: 0.802-0.88), respectively. In the external
validation set, the AUCs were 0.856 (95% CI: 0.838-0.882), 0.787 (95% CI:
0.757-0.818), and 0.793 (95% CI: 0.758-0.831) for ccRCC, pRCC, and chRCC,
respectively. Conclusions The developed deep learning model demonstrated robust
performance in predicting the pathological subtypes of RCC, while the
incorporated uncertainty emphasized the importance of understanding model
confidence, which is crucial for assisting clinical decision-making for
patients with renal tumors. Clinical relevance statement Our deep learning
approach, integrated with uncertainty estimation, offers clinicians a dual
advantage: accurate RCC subtype predictions complemented by diagnostic
confidence references, promoting informed decision-making for patients with
RCC.Comment: 16 pages, 6 figure
Incremental Value and Interpretability of Radiomics Features of Both Lung and Epicardial Adipose Tissue for Detecting the Severity of COVID-19 Infection
Epicardial adipose tissue (EAT) is known for its pro-inflammatory properties
and association with Coronavirus Disease 2019 (COVID-19) severity. However,
current EAT segmentation methods do not consider positional information.
Additionally, the detection of COVID-19 severity lacks consideration for EAT
radiomics features, which limits interpretability. This study investigates the
use of radiomics features from EAT and lungs to detect the severity of COVID-19
infections. A retrospective analysis of 515 patients with COVID-19 (Cohort1:
415, Cohort2: 100) was conducted using a proposed three-stage deep learning
approach for EAT extraction. Lung segmentation was achieved using a published
method. A hybrid model for detecting the severity of COVID-19 was built in a
derivation cohort, and its performance and uncertainty were evaluated in
internal (125, Cohort1) and external (100, Cohort2) validation cohorts. For EAT
extraction, the Dice similarity coefficients (DSC) of the two centers were
0.972 (+-0.011) and 0.968 (+-0.005), respectively. For severity detection, the
hybrid model with radiomics features of both lungs and EAT showed improvements
in AUC, net reclassification improvement (NRI), and integrated discrimination
improvement (IDI) compared to the model with only lung radiomics features. The
hybrid model exhibited an increase of 0.1 (p<0.001), 19.3%, and 18.0%
respectively, in the internal validation cohort and an increase of 0.09
(p<0.001), 18.0%, and 18.0%, respectively, in the external validation cohort
while outperforming existing detection methods. Uncertainty quantification and
radiomics features analysis confirmed the interpretability of case prediction
after inclusion of EAT features.Comment: 20 pages, 7 figure
Dysregulated protocadherin-pathway activity as an intrinsic defect in induced pluripotent stem cell-derived cortical interneurons from subjects with schizophrenia.
We generated cortical interneurons (cINs) from induced pluripotent stem cells derived from 14 healthy controls and 14 subjects with schizophrenia. Both healthy control cINs and schizophrenia cINs were authentic, fired spontaneously, received functional excitatory inputs from host neurons, and induced GABA-mediated inhibition in host neurons in vivo. However, schizophrenia cINs had dysregulated expression of protocadherin genes, which lie within documented schizophrenia loci. Mice lacking protocadherin-α showed defective arborization and synaptic density of prefrontal cortex cINs and behavioral abnormalities. Schizophrenia cINs similarly showed defects in synaptic density and arborization that were reversed by inhibitors of protein kinase C, a downstream kinase in the protocadherin pathway. These findings reveal an intrinsic abnormality in schizophrenia cINs in the absence of any circuit-driven pathology. They also demonstrate the utility of homogenous and functional populations of a relevant neuronal subtype for probing pathogenesis mechanisms during development
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