147 research outputs found
The Topology of Foliations Formed by the Generic K-Orbits of a Subclass of the Indecomposable MD5-Groups
The present paper is a continuation of [13], [14] of the authors.
Specifically, the paper considers the MD5-foliations associated to connected
and simply connected MD5-groups such that their Lie algebras have 4-dimensional
commutative derived ideal. In the paper, we give the topological classification
of all considered MD5-foliations. A description of these foliations by certain
fibrations or suitable actions of and the Connes' C*-algebras
of the foliations which come from fibrations are also given in the paper.Comment: 20 pages, no figur
n-Gram-based text compression
We propose an efficient method for compressing Vietnamese text using n-gram dictionaries. It has a significant compression ratio in comparison with those of state-of-the-art methods on the same dataset. Given a text, first, the proposed method splits it into n-grams and then encodes them based on n-gram dictionaries. In the encoding phase, we use a sliding window with a size that ranges from bigram to five grams to obtain the best encoding stream. Each n-gram is encoded by two to four bytes accordingly based on its corresponding n-gram dictionary. We collected 2.5 GB text corpus from some Vietnamese news agencies to build n-gram dictionaries from unigram to five grams and achieve dictionaries with a size of 12 GB in total. In order to evaluate our method, we collected a testing set of 10 different text files with different sizes. The experimental results indicate that our method achieves compression ratio around 90% and outperforms state-of-the-art methods.Web of Scienceart. no. 948364
Unlocking the capabilities of explainable fewshot learning in remote sensing
Recent advancements have significantly improved the efficiency and
effectiveness of deep learning methods for imagebased remote sensing tasks.
However, the requirement for large amounts of labeled data can limit the
applicability of deep neural networks to existing remote sensing datasets. To
overcome this challenge, fewshot learning has emerged as a valuable approach
for enabling learning with limited data. While previous research has evaluated
the effectiveness of fewshot learning methods on satellite based datasets,
little attention has been paid to exploring the applications of these methods
to datasets obtained from UAVs, which are increasingly used in remote sensing
studies. In this review, we provide an up to date overview of both existing and
newly proposed fewshot classification techniques, along with appropriate
datasets that are used for both satellite based and UAV based data. Our
systematic approach demonstrates that fewshot learning can effectively adapt to
the broader and more diverse perspectives that UAVbased platforms can provide.
We also evaluate some SOTA fewshot approaches on a UAV disaster scene
classification dataset, yielding promising results. We emphasize the importance
of integrating XAI techniques like attention maps and prototype analysis to
increase the transparency, accountability, and trustworthiness of fewshot
models for remote sensing. Key challenges and future research directions are
identified, including tailored fewshot methods for UAVs, extending to unseen
tasks like segmentation, and developing optimized XAI techniques suited for
fewshot remote sensing problems. This review aims to provide researchers and
practitioners with an improved understanding of fewshot learnings capabilities
and limitations in remote sensing, while highlighting open problems to guide
future progress in efficient, reliable, and interpretable fewshot methods.Comment: Under review, once the paper is accepted, the copyright will be
transferred to the corresponding journa
WATT-EffNet: A Lightweight and Accurate Model for Classifying Aerial Disaster Images
Incorporating deep learning (DL) classification models into unmanned aerial
vehicles (UAVs) can significantly augment search-and-rescue operations and
disaster management efforts. In such critical situations, the UAV's ability to
promptly comprehend the crisis and optimally utilize its limited power and
processing resources to narrow down search areas is crucial. Therefore,
developing an efficient and lightweight method for scene classification is of
utmost importance. However, current approaches tend to prioritize accuracy on
benchmark datasets at the expense of computational efficiency. To address this
shortcoming, we introduce the Wider ATTENTION EfficientNet (WATT-EffNet), a
novel method that achieves higher accuracy with a more lightweight architecture
compared to the baseline EfficientNet. The WATT-EffNet leverages width-wise
incremental feature modules and attention mechanisms over width-wise features
to ensure the network structure remains lightweight. We evaluate our method on
a UAV-based aerial disaster image classification dataset and demonstrate that
it outperforms the baseline by up to 15 times in terms of classification
accuracy and in terms of computing efficiency as measured by Floating
Point Operations per second (FLOPs). Additionally, we conduct an ablation study
to investigate the effect of varying the width of WATT-EffNet on accuracy and
computational efficiency. Our code is available at
\url{https://github.com/TanmDL/WATT-EffNet}.Comment: This paper is accepted in IEEE Trans. GRS
The transfer and decay of maternal antibody against Shigella sonnei in a longitudinal cohort of Vietnamese infants.
BACKGROUND: Shigella sonnei is an emergent and major diarrheal pathogen for which there is currently no vaccine. We aimed to quantify duration of maternal antibody against S. sonnei and investigate transplacental IgG transfer in a birth cohort in southern Vietnam. METHODS AND RESULTS: Over 500-paired maternal/infant plasma samples were evaluated for presence of anti-S. sonnei-O IgG and IgM. Longitudinal plasma samples allowed for the estimation of the median half-life of maternal anti-S. sonnei-O IgG, which was 43 days (95% confidence interval: 41-45 days). Additionally, half of infants lacked a detectable titer by 19 weeks of age. Lower cord titers were associated with greater increases in S. sonnei IgG over the first year of life, and the incidence of S. sonnei seroconversion was estimated to be 4/100 infant years. Maternal IgG titer, the ratio of antibody transfer, the season of birth and gestational age were significantly associated with cord titer. CONCLUSIONS: Maternal anti-S. sonnei-O IgG is efficiently transferred across the placenta and anti-S. sonnei-O maternal IgG declines rapidly after birth and is undetectable after 5 months in the majority of children. Preterm neonates and children born to mothers with low IgG titers have lower cord titers and therefore may be at greater risk of seroconversion in infancy
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The impact of environmental and climatic variation on the spatiotemporal trends of hospitalized pediatric diarrhea in Ho Chi Minh City, Vietnam.
It is predicted that the integration of climate-based early warning systems into existing action plans will facilitate the timely provision of interventions to diarrheal disease epidemics in resource-poor settings. Diarrhea remains a considerable public health problem in Ho Chi Minh City (HCMC), Vietnam and we aimed to quantify variation in the impact of environmental conditions on diarrheal disease risk across the city. Using all inpatient diarrheal admissions data from three large hospitals within HCMC, we developed a mixed effects regression model to differentiate district-level variation in risk due to environmental conditions from the overarching seasonality of diarrheal disease hospitalization in HCMC. We identified considerable spatial heterogeneity in the risk of all-cause diarrhea across districts of HCMC with low elevation and differential responses to flooding, air temperature, and humidity driving further spatial heterogeneity in diarrheal disease risk. The incorporation of these results into predictive forecasting algorithms will provide a powerful resource to aid diarrheal disease prevention and control practices in HCMC and other similar settings
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