107 research outputs found
P1-210: Prognostic analysis of Small Cell Lung Cancer (SCLC) treated with postoperative chemotherapy
Inductive Graph Neural Networks for Spatiotemporal Kriging
Time series forecasting and spatiotemporal kriging are the two most important
tasks in spatiotemporal data analysis. Recent research on graph neural networks
has made substantial progress in time series forecasting, while little
attention has been paid to the kriging problem -- recovering signals for
unsampled locations/sensors. Most existing scalable kriging methods (e.g.,
matrix/tensor completion) are transductive, and thus full retraining is
required when we have a new sensor to interpolate. In this paper, we develop an
Inductive Graph Neural Network Kriging (IGNNK) model to recover data for
unsampled sensors on a network/graph structure. To generalize the effect of
distance and reachability, we generate random subgraphs as samples and
reconstruct the corresponding adjacency matrix for each sample. By
reconstructing all signals on each sample subgraph, IGNNK can effectively learn
the spatial message passing mechanism. Empirical results on several real-world
spatiotemporal datasets demonstrate the effectiveness of our model. In
addition, we also find that the learned model can be successfully transferred
to the same type of kriging tasks on an unseen dataset. Our results show that:
1) GNN is an efficient and effective tool for spatial kriging; 2) inductive
GNNs can be trained using dynamic adjacency matrices; 3) a trained model can be
transferred to new graph structures and 4) IGNNK can be used to generate
virtual sensors.Comment: AAAI 202
Enhancing Representation Learning for Periodic Time Series with Floss: A Frequency Domain Regularization Approach
Time series analysis is a fundamental task in various application domains,
and deep learning approaches have demonstrated remarkable performance in this
area. However, many real-world time series data exhibit significant periodic or
quasi-periodic dynamics that are often not adequately captured by existing deep
learning-based solutions. This results in an incomplete representation of the
underlying dynamic behaviors of interest. To address this gap, we propose an
unsupervised method called Floss that automatically regularizes learned
representations in the frequency domain. The Floss method first automatically
detects major periodicities from the time series. It then employs periodic
shift and spectral density similarity measures to learn meaningful
representations with periodic consistency. In addition, Floss can be easily
incorporated into both supervised, semi-supervised, and unsupervised learning
frameworks. We conduct extensive experiments on common time series
classification, forecasting, and anomaly detection tasks to demonstrate the
effectiveness of Floss. We incorporate Floss into several representative deep
learning solutions to justify our design choices and demonstrate that it is
capable of automatically discovering periodic dynamics and improving
state-of-the-art deep learning models.Comment: 12 page
On-the-fly scheduling vs. reservation-based scheduling for unpredictable workflows
International audienceScientific insights in the coming decade will clearly depend on the effective processing of large datasets generated by dynamic heterogeneous applications typical of workflows in large data centers or of emerging fields like neuroscience. In this paper, we show how these big data workflows have a unique set of characteristics that pose challenges for leveraging HPC methodologies, particularly in scheduling. Our findings indicate that execution times for these workflows are highly unpredictable and are not correlated with the size of the dataset involved or the precise functions used in the analysis. We characterize this inherent variability and sketch the need for new scheduling approaches by quantifying significant gaps in achievable performance. Through simulations, we show how on-the-fly scheduling approaches can deliver benefits in both system-level and user-level performance measures. On average, we find improvements of up to 35% in system utilization and up to 45% in average stretch of the applications, illustrating the potential of increasing performance through new scheduling approaches
Cell Spatial Analysis in Crohn's Disease: Unveiling Local Cell Arrangement Pattern with Graph-based Signatures
Crohn's disease (CD) is a chronic and relapsing inflammatory condition that
affects segments of the gastrointestinal tract. CD activity is determined by
histological findings, particularly the density of neutrophils observed on
Hematoxylin and Eosin stains (H&E) imaging. However, understanding the broader
morphometry and local cell arrangement beyond cell counting and tissue
morphology remains challenging. To address this, we characterize six distinct
cell types from H&E images and develop a novel approach for the local spatial
signature of each cell. Specifically, we create a 10-cell neighborhood matrix,
representing neighboring cell arrangements for each individual cell. Utilizing
t-SNE for non-linear spatial projection in scatter-plot and Kernel Density
Estimation contour-plot formats, our study examines patterns of differences in
the cellular environment associated with the odds ratio of spatial patterns
between active CD and control groups. This analysis is based on data collected
at the two research institutes. The findings reveal heterogeneous
nearest-neighbor patterns, signifying distinct tendencies of cell clustering,
with a particular focus on the rectum region. These variations underscore the
impact of data heterogeneity on cell spatial arrangements in CD patients.
Moreover, the spatial distribution disparities between the two research sites
highlight the significance of collaborative efforts among healthcare
organizations. All research analysis pipeline tools are available at
https://github.com/MASILab/cellNN.Comment: Submitted to SPIE Medical Imaging. San Diego, CA. February 202
Rubber Toughened and Nanoparticle Reinforced Epoxy Composites
Epoxy resins have achieved acceptance as adhesives, coatings, and potting compounds,
but their main application is as matrix to produce reinforced composites.
However, their usefulness in this field still limited due to their brittle nature. Some
studies have been done to increase the toughness of epoxy composites, of which the
most successful one is the modification of the polymer matrix with a second toughening
phase.
Resin Transfer Molding (RTM) is one of the most important technologies to manufacture
fiber reinforced composites. In the last decade it has experimented new impulse,
due to its favorable application to produce large surface composites with good technical
properties and at relative low cost.
This research work focuses on the development of novel modified epoxy matrices,
with enhanced mechanical and thermal properties, suitable to be processed by resin
transfer molding technology, to manufacture Glass Fiber Reinforced Composites
(GFRC’s) with improved performance in comparison to the commercially available
ones.
In the first stage of the project, a neat epoxy resin (EP) was modified using two different
nano-sized ceramics: silicium dioxide (SiO2) and zirconium dioxide (ZrO2); and
micro-sized particles of silicone rubber (SR) as second filler. Series of nanocomposites
and hybrid modified epoxy resins were obtained by systematic variation of filler
contents. The rheology and curing process of the modified epoxy resins were determined
in order to define their aptness to be processed by RTM. The resulting matrices
were extensively characterized qualitatively and quantitatively to precise the effect
of each filler on the polymer properties.
It was shown that the nanoparticles confer better mechanical properties to the epoxy
resin, including modulus and toughness. It was possible to improve simultaneously
the tensile modulus and toughness of the epoxy matrix in more than 30 % and 50 %
respectively, only by using 8 vol.-% nano-SiO2 as filler. A similar performance was
obtained by nanocomposites containing zirconia. The epoxy matrix modified with 8 vol.-% ZrO2 recorded tensile modulus and toughness improved up to 36% and 45%
respectively regarding EP.
On the other hand, the addition of silicone rubber to EP and nanocomposites results
in a superior toughness but has a slightly negative effect on modulus and strength.
The addition of 3 vol.-% SR to the neat epoxy and nanocomposites increases their
toughness between 1.5 and 2.5 fold; but implies also a reduction in their tensile modulus
and strength in range 5-10%. Therefore, when the right proportion of nanoceramic
and rubber were added to the epoxy resin, hybrid epoxy matrices with fracture
toughness 3 fold higher than EP but also with up to 20% improved modulus were
obtained.
Widespread investigations were carried out to define the structural mechanisms responsible
for these improvements. It was stated, that each type of filler induces specific
energy dissipating mechanisms during the mechanical loading and fracture
processes, which are closely related to their nature, morphology and of course to
their bonding with the epoxy matrix. When both nanoceramic and silicone rubber are
involved in the epoxy formulation, a superposition of their corresponding energy release
mechanisms is generated, which provides the matrix with an unusual properties
balance.
From the modified matrices glass fiber reinforced RTM-plates were produced. The
structure of the obtained composites was microscopically analyzed to determine their
impregnation quality. In all cases composites with no structural defects (i.e. voids,
delaminations) and good superficial finish were reached. The composites were also
properly characterized. As expected the final performance of the GFRCs is strongly
determined by the matrix properties. Thus, the enhancement reached by epoxy matrices
is translated into better GFRC´s macroscopical properties. Composites with up
to 15% enhanced strength and toughness improved up to 50%, were obtained from
the modified epoxy matrices
Association Between Whole Blood-Derived Mitochondrial Dna Copy Number, Low-Density Lipoprotein Cholesterol, and Cardiovascular Disease Risk
Background The relationship between mitochondrial DNA copy number (mtDNA CN) and cardiovascular disease remains elusive. Methods and Results We performed cross-sectional and prospective association analyses of blood-derived mtDNA CN and cardiovascular disease outcomes in 27 316 participants in 8 cohorts of multiple racial and ethnic groups with whole-genome sequencing. We also performed Mendelian randomization to explore causal relationships of mtDNA CN with coronary heart disease (CHD) and cardiometabolic risk factors (obesity, diabetes, hypertension, and hyperlipidemia)
Stem cell-based ischemic stroke therapy: Novel modifications and clinical challenges
Ischemic stroke (IS) causes severe disability and high mortality worldwide. Stem cell (SC) therapy exhibits unique therapeutic potential for IS that differs from current treatments. SC's cell homing, differentiation and paracrine abilities give hope for neuroprotection. Recent studies on SC modification have enhanced therapeutic effects for IS, including gene transfection, nanoparticle modification, biomaterial modification and pretreatment. These methods improve survival rate, homing, neural differentiation, and paracrine abilities in ischemic areas. However, many problems must be resolved before SC therapy can be clinically applied. These issues include production quality and quantity, stability during transportation and storage, as well as usage regulations. Herein, we reviewed the brief pathogenesis of IS, the “multi-mechanism” advantages of SCs for treating IS, various SC modification methods, and SC therapy challenges. We aim to uncover the potential and overcome the challenges of using SCs for treating IS and convey innovative ideas for modifying SCs
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