350 research outputs found
Visualizing Convolutional Networks for MRI-based Diagnosis of Alzheimer's Disease
Visualizing and interpreting convolutional neural networks (CNNs) is an
important task to increase trust in automatic medical decision making systems.
In this study, we train a 3D CNN to detect Alzheimer's disease based on
structural MRI scans of the brain. Then, we apply four different gradient-based
and occlusion-based visualization methods that explain the network's
classification decisions by highlighting relevant areas in the input image. We
compare the methods qualitatively and quantitatively. We find that all four
methods focus on brain regions known to be involved in Alzheimer's disease,
such as inferior and middle temporal gyrus. While the occlusion-based methods
focus more on specific regions, the gradient-based methods pick up distributed
relevance patterns. Additionally, we find that the distribution of relevance
varies across patients, with some having a stronger focus on the temporal lobe,
whereas for others more cortical areas are relevant. In summary, we show that
applying different visualization methods is important to understand the
decisions of a CNN, a step that is crucial to increase clinical impact and
trust in computer-based decision support systems.Comment: MLCN 201
De kracht van de gemeenschap
Met het verschijnen van het regeerakkoord van het kabinet Rutte II is de discussie over de inrichting van het Nederlands openbaar bestuur in een stroomversnelling geraakt. De passages over een gewenste minimumomvang van gemeenten van 100.000 inwoners en een lange termijn perspectief van vijf te vormen landsdelen hebben de agenda vooral bepaald. Dit ondanks nuanceringen in het akkoord zelf en verwoede pogingen van bewindspersonen om een en ander in perspectief te plaatsen. Jammer, want daarmee wordt de discussie minder gevoerd waarover deze zou moeten gaan. Namelijk de discussie waar, op welke plek, taken in de samenleving het beste belegd kunnen worden
Performance analysis of wireless LANs: an integrated packet/flow level approach
In this paper we present an integrated packet/flow level modelling approach for analysing flow throughputs and transfer times in IEEE 802.11 WLANs. The packet level model captures the statistical characteristics of the transmission of individual packets at the MAC layer, while the flow level model takes into account the system dynamics due to the initiation and completion of data flow transfers. The latter model is a processor sharing type of queueing model reflecting the IEEE 802.11 MAC design principle of distributing the transmission capacity fairly among the active flows. The resulting integrated packet/flow level model is analytically tractable and yields a simple approximation for the throughput and flow transfer time. Extensive simulations show that the approximation is very accurate for a wide range of parameter settings. In addition, the simulation study confirms the attractive property following from our approximation that the expected flow transfer delay is insensitive to the flow size distribution (apart from its mean)
End stage renal disease patients have a skewed T cell receptor Vβ repertoire
BACKGROUND: End stage renal disease (ESRD) is associated with defective T-cell mediated immunity. A diverse T-cell receptor (TCR) Vβ repertoire is central to effective T-cell mediated immune responses to foreign antigens. In this study, the effect of ESRD on TCR Vβ repertoire was assessed. RESULTS: A higher proportion of ESRD patients (68.9 %) had a skewed TCR Vβ repertoire compared to age and cytomegalovirus (CMV) – IgG serostatus matched healthy individuals (31.4 %, P < 0.001). Age, CMV serostatus and ESRD were independently associated with an increase in shifting of the TCR Vβ repertoire. More differentiated CD8(+) T cells were observed in young ESRD patients with a shifted TCR Vβ repertoire. CD31-expressing naive T cells and relative telomere length of T cells were not significantly related to TCR Vβ skewing. CONCLUSIONS: ESRD significantly skewed the TCR Vβ repertoire particularly in the elderly population, which may contribute to the uremia-associated defect in T-cell mediated immunity. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12979-015-0055-7) contains supplementary material, which is available to authorized users
Current Tolerance-Associated Peripheral Blood Gene Expression Profiles After Liver Transplantation Are Influenced by Immunosuppressive Drugs and Prior Cytomegalovirus Infection
Spontaneous operational tolerance to the allograft develops in a proportion of liver transplant (LTx) recipients weaned off immunosuppressive drugs (IS). Several previous studies have investigated whether peripheral blood gene expression profiles could identify operational tolerance in LTx recipients. However, the reported gene expression profiles differed greatly amongst studies, which could be caused by inadequate matching of clinical parameters of study groups. Therefore, the purpose of this study was to validate differentially expressed immune system related genes described in previous studies that identified tolerant LTx recipients after IS weaning. Blood was collected of tolerant LTx recipients (TOL), a control group of LTx recipients with regular IS regimen (CTRL), a group of LTx recipients with minimal IS regimen (MIN) and healthy controls (HC), and groups were matched on age, sex, primary disease, time after LTx, and cytomegalovirus serostatus after LTx. Quantitative Polymerase Chain Reaction was used to determine expression of twenty selected genes and transcript variants in PBMCs. Several genes were differentially expressed between TOL and CTRL groups, but none of the selected genes were differentially expressed between HC and TOL. Principal component analysis revealed an IS drug dosage effect on the expression profile of these genes. These data suggest that use of IS profoundly affects gene expression in peripheral blood, and that these genes are not associated with operational tolerance. In addition, expression levels of SLAMF7 and NKG7 were affected by prior cytomegalovirus infection in LTx recipients. In conclusion, we found confounding effects of IS regimen and prior cytomegalovirus infection, on peripheral blood expression of several selected genes that were described as tolerance-associated genes by previous studies
Distributed Ledger for Provenance Tracking of Artificial Intelligence Assets
High availability of data is responsible for the current trends in Artificial
Intelligence (AI) and Machine Learning (ML). However, high-grade datasets are
reluctantly shared between actors because of lacking trust and fear of losing
control. Provenance tracing systems are a possible measure to build trust by
improving transparency. Especially the tracing of AI assets along complete AI
value chains bears various challenges such as trust, privacy, confidentiality,
traceability, and fair remuneration. In this paper we design a graph-based
provenance model for AI assets and their relations within an AI value chain.
Moreover, we propose a protocol to exchange AI assets securely to selected
parties. The provenance model and exchange protocol are then combined and
implemented as a smart contract on a permission-less blockchain. We show how
the smart contract enables the tracing of AI assets in an existing industry use
case while solving all challenges. Consequently, our smart contract helps to
increase traceability and transparency, encourages trust between actors and
thus fosters collaboration between them
Differential effects of age, cytomegalovirus-seropositivity and end-stage renal disease (ESRD) on circulating T lymphocyte subsets
The age- and cytomegalovirus (CMV)-seropositivity-related changes in subsets and differentiation of circulating T cells were investigated in end-stage renal disease (ESRD) patients (n = 139) and age-matched healthy individuals. The results show that CMV-seropositivity is associated with expansion of both CD4+ and CD8+ memory T cells which is already observed in young healthy individuals. In addition, CMV-seropositive healthy individuals have a more differentiated memory T cell profile. Only CMV-seropositive healthy individuals showed an age-dependent decrease in CD4+ naïve T cells. The age-related decrease in the number of CD8+ naïve T cells was CMV-independent. In contrast, all ESRD patients showed a profound naïve T-cell lymphopenia at every decade. CMV-seropositivity aggravated the contraction of CD4+ naïve T cells and increased the number of differentiated CD4+ and CD8+ memory T cells. In conclusion, CMV-seropositivity markedly alters the homeostasis of circulating T cells in healthy individuals and aggravates the T cell dysregulation observed in ESRD patients
Deep Placental Vessel Segmentation for Fetoscopic Mosaicking
During fetoscopic laser photocoagulation, a treatment for twin-to-twin
transfusion syndrome (TTTS), the clinician first identifies abnormal placental
vascular connections and laser ablates them to regulate blood flow in both
fetuses. The procedure is challenging due to the mobility of the environment,
poor visibility in amniotic fluid, occasional bleeding, and limitations in the
fetoscopic field-of-view and image quality. Ideally, anastomotic placental
vessels would be automatically identified, segmented and registered to create
expanded vessel maps to guide laser ablation, however, such methods have yet to
be clinically adopted. We propose a solution utilising the U-Net architecture
for performing placental vessel segmentation in fetoscopic videos. The obtained
vessel probability maps provide sufficient cues for mosaicking alignment by
registering consecutive vessel maps using the direct intensity-based technique.
Experiments on 6 different in vivo fetoscopic videos demonstrate that the
vessel intensity-based registration outperformed image intensity-based
registration approaches showing better robustness in qualitative and
quantitative comparison. We additionally reduce drift accumulation to
negligible even for sequences with up to 400 frames and we incorporate a scheme
for quantifying drift error in the absence of the ground-truth. Our paper
provides a benchmark for fetoscopy placental vessel segmentation and
registration by contributing the first in vivo vessel segmentation and
fetoscopic videos dataset.Comment: Accepted at MICCAI 202
Machine Learning Approach for the Early Prediction of the Risk of Overweight and Obesity in Young People
Obesity is a major global concern with more than 2.1 billion people overweight or obese worldwide which amounts to almost 30% of the global population. If the current trend continues, the overweight and obese population is likely to increase to 41% by 2030. Individuals developing signs of weight gain or obesity are also at a risk of developing serious illnesses such as type 2 diabetes, respiratory problems, heart disease and stroke. Some intervention measures such as physical activity and healthy eating can be a fundamental component to maintain a healthy lifestyle. Therefore, it is absolutely essential to detect childhood obesity as early as possible. This paper utilises the vast amount of data available via UK’s millennium cohort study in order to construct a machine learning driven model to predict young people at the risk of becoming overweight or obese. The childhood BMI values from the ages 3, 5, 7 and 11 are used to predict adolescents of age 14 at the risk of becoming overweight or obese. There is an inherent imbalance in the dataset of individuals with normal BMI and the ones at risk. The results obtained are encouraging and a prediction accuracy of over 90% for the target class has been achieved. Various issues relating to data preprocessing and prediction accuracy are addressed and discussed
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