221 research outputs found
Analysis of (sub-)Riemannian PDE-G-CNNs
Group equivariant convolutional neural networks (G-CNNs) have been
successfully applied in geometric deep learning. Typically, G-CNNs have the
advantage over CNNs that they do not waste network capacity on training
symmetries that should have been hard-coded in the network. The recently
introduced framework of PDE-based G-CNNs (PDE-G-CNNs) generalises G-CNNs.
PDE-G-CNNs have the core advantages that they simultaneously 1) reduce network
complexity, 2) increase classification performance, and 3) provide geometric
interpretability. Their implementations primarily consist of linear and
morphological convolutions with kernels.
In this paper we show that the previously suggested approximative
morphological kernels do not always accurately approximate the exact kernels
accurately. More specifically, depending on the spatial anisotropy of the
Riemannian metric, we argue that one must resort to sub-Riemannian
approximations. We solve this problem by providing a new approximative kernel
that works regardless of the anisotropy. We provide new theorems with better
error estimates of the approximative kernels, and prove that they all carry the
same reflectional symmetries as the exact ones.
We test the effectiveness of multiple approximative kernels within the
PDE-G-CNN framework on two datasets, and observe an improvement with the new
approximative kernels. We report that the PDE-G-CNNs again allow for a
considerable reduction of network complexity while having comparable or better
performance than G-CNNs and CNNs on the two datasets. Moreover, PDE-G-CNNs have
the advantage of better geometric interpretability over G-CNNs, as the
morphological kernels are related to association fields from neurogeometry.Comment: 29 pages, 21 figure
Identifying risk factors for Jihadist terrorist offenders committing homicide: An explorative analysis using the European Database of Terrorist offenders
Although many studies have examined various aspects of terrorism, relatively little is known about risk indicators associated with specific types of terrorist offences. To partly fill this void, this study explores differences on risk indicators of the Violent Extremism Risk Assessment tool (VERA-2R) between 21 Jihadist offenders who were convicted for homicide and a comparison group of 30 Jihadist offenders convicted for other Jihadist terrorist offences. In doing so, we use judicial data from the European Database of Terrorist offenders (EDT). The results reveal that a number of risk and protective indicators differ between both groups. Both terrorist offender groups often expressed grievances about perceived injustice, but the homicide group more frequently expressed anger, moral outrage, or hatred in response to the perceived injustice than the comparison group. The homicide group also identified their attacks more often than the comparison group, and were more actively engaged in planning and preparation them. Additionally, the homicide group was less often motivated to commit their terrorist offences by group belonging compared with the non-homicide group. With respect to the protective indicators, persons in the comparison group more often reject violence as a means to achieve goals. Although further research is necessary, the results from this study indicate that a differentiated approach might be needed for risk assessment and risk management of the terrorist offender population
Procalcitonin as a potent marker of bacterial infection in febrile Afro-Caribbean patients at the emergency department
Procalcitonin (PCT) has been shown to be of additional value in the work-up of a febrile patient. This study is the first to investigate the additional value of PCT in an Afro-Caribbean febrile population at the emergency department (ED) of a general hospital. Febrile patients were included at the ED. Prospective, blinded PCT measurements were performed in patients with a microbiologically or serologically confirmed diagnosis or a strongly suspected diagnosis on clinical grounds. PCT analysis was performed in 93 patients. PCT levels differentiated well between confirmed bacterial and confirmed viral infection (area under the curve [AUC] of 0.82, sensitivity 85%, specificity 69%, cut-off 0.24Â ng/mL), between confirmed bacterial infection and non-infectious fever (AUC of 0.84, sensitivity 90%, specificity 71%, cut-off 0.21Â ng/mL) and between all bacterial infections (confirmed and suspected) and non-infectious fever (AUC of 0.80, sensitivity 85%, specificity 71%, cut-off 0.21Â ng/mL). C-reactive protein (CRP) levels were shown to be less accurate when comparing the same groups. This is the first study showing that, in a non-Caucasian febrile population at the ED, PCT is a more valuable marker of bacterial infection than CRP. These results may improve diagnostics and eventually decrease antibiotic prescriptions in resource-limited settings
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Culture and Subjectivity in Neoliberal and postfeminist times
My aim in this paper is to think through a number of issues concerning the relationship between culture and subjectivity. It seems to me that exploring the relationship of changing forms of political organisation, social relations and cultural practices to changing modes and experiences of subjecthood and subjectivity are among the most important and urgent tasks for critical intellectual work. These questions go to the heart of understanding power, ideology and agency and they require research that is interdisciplinary, psychosocial and intersectional. My particular focus in this short article is on the interrelations between changing representational practices in visual culture and changing subjectivity/ies. I argue that neoliberalism and postfeminism are central to understanding contemporary media culture, and I put the case for research which does not retreat from exploring how these broader social/political/economic/cultural discourses and formations may relate to subjectivity
Non-intersecting squared Bessel paths at a hard-edge tacnode
The squared Bessel process is a 1-dimensional diffusion process related to
the squared norm of a higher dimensional Brownian motion. We study a model of
non-intersecting squared Bessel paths, with all paths starting at the same
point at time and ending at the same point at time . Our
interest lies in the critical regime , for which the paths are tangent
to the hard edge at the origin at a critical time . The critical
behavior of the paths for is studied in a scaling limit with time
and temperature . This leads to a critical
correlation kernel that is defined via a new Riemann-Hilbert problem of size
. The Riemann-Hilbert problem gives rise to a new Lax pair
representation for the Hastings-McLeod solution to the inhomogeneous Painlev\'e
II equation where with
the parameter of the squared Bessel process. These results extend
our recent work with Kuijlaars and Zhang \cite{DKZ} for the homogeneous case
.Comment: 54 pages, 13 figures. Corrected error in Theorem 2.
A deep learning system for detection of early Barrett's neoplasia:a model development and validation study
BACKGROUND: Computer-aided detection (CADe) systems could assist endoscopists in detecting early neoplasia in Barrett's oesophagus, which could be difficult to detect in endoscopic images. The aim of this study was to develop, test, and benchmark a CADe system for early neoplasia in Barrett's oesophagus.METHODS: The CADe system was first pretrained with ImageNet followed by domain-specific pretraining with GastroNet. We trained the CADe system on a dataset of 14 046 images (2506 patients) of confirmed Barrett's oesophagus neoplasia and non-dysplastic Barrett's oesophagus from 15 centres. Neoplasia was delineated by 14 Barrett's oesophagus experts for all datasets. We tested the performance of the CADe system on two independent test sets. The all-comers test set comprised 327 (73 patients) non-dysplastic Barrett's oesophagus images, 82 (46 patients) neoplastic images, 180 (66 of the same patients) non-dysplastic Barrett's oesophagus videos, and 71 (45 of the same patients) neoplastic videos. The benchmarking test set comprised 100 (50 patients) neoplastic images, 300 (125 patients) non-dysplastic images, 47 (47 of the same patients) neoplastic videos, and 141 (82 of the same patients) non-dysplastic videos, and was enriched with subtle neoplasia cases. The benchmarking test set was evaluated by 112 endoscopists from six countries (first without CADe and, after 6 weeks, with CADe) and by 28 external international Barrett's oesophagus experts. The primary outcome was the sensitivity of Barrett's neoplasia detection by general endoscopists without CADe assistance versus with CADe assistance on the benchmarking test set. We compared sensitivity using a mixed-effects logistic regression model with conditional odds ratios (ORs; likelihood profile 95% CIs).FINDINGS: Sensitivity for neoplasia detection among endoscopists increased from 74% to 88% with CADe assistance (OR 2·04; 95% CI 1·73-2·42; p<0·0001 for images and from 67% to 79% [2·35; 1·90-2·94; p<0·0001] for video) without compromising specificity (from 89% to 90% [1·07; 0·96-1·19; p=0·20] for images and from 96% to 94% [0·94; 0·79-1·11; ] for video; p=0·46). In the all-comers test set, CADe detected neoplastic lesions in 95% (88-98) of images and 97% (90-99) of videos. In the benchmarking test set, the CADe system was superior to endoscopists in detecting neoplasia (90% vs 74% [OR 3·75; 95% CI 1·93-8·05; p=0·0002] for images and 91% vs 67% [11·68; 3·85-47·53; p<0·0001] for video) and non-inferior to Barrett's oesophagus experts (90% vs 87% [OR 1·74; 95% CI 0·83-3·65] for images and 91% vs 86% [2·94; 0·99-11·40] for video).INTERPRETATION: CADe outperformed endoscopists in detecting Barrett's oesophagus neoplasia and, when used as an assistive tool, it improved their detection rate. CADe detected virtually all neoplasia in a test set of consecutive cases.FUNDING: Olympus.</p
T Lymphocytes Promote the Antiviral and Inflammatory Responses of Airway Epithelial Cells
T cells modulate the antiviral and inflammatory responses of airway epithelial cells to human rhinoviruses (HRV)
The Tissue Systems Pathology Test Outperforms Pathology Review in Risk Stratifying Patients With Low-Grade Dysplasia
BACKGROUND & AIMS:
Low-grade dysplasia (LGD) is associated with an increased risk of progression in Barrett’s esophagus (BE); however, the diagnosis of LGD is limited by substantial interobserver variability. Multiple studies have shown that an objective tissue systems pathology test (TissueCypher Barrett’s Esophagus Test, TSP-9), can effectively predict neoplastic progression in patients with BE. This study aimed to compare the risk stratification performance of the TSP-9 test vs benchmarks of generalist and expert pathology.
METHODS:
A blinded cohort study was conducted in the screening cohort of a randomized controlled trial of patients with BE with community-based LGD. Biopsies from the first endoscopy with LGD were assessed by the TSP-9 test and independently reviewed by 30 pathologists from 5 countries per standard practice. The accuracy of the test and the diagnoses in predicting high-grade dysplasia (HGD) and esophageal adenocarcinoma (EAC) were compared.
RESULTS:
A total of 154 patients with BE (122 men), mean age 60.9 ± 9.8 years were studied. Twenty-four patients progressed to HGD/EAC within 5 years (median time of 1.7 years) and 130 did not progress to HGD/EAC within 5 years (median 7.8 years follow-up). The TSP-9 test demonstrated higher sensitivity (71% vs mean 63%, range 33%–88% across 30 pathologists), than the pathology review in detecting patients who progressed (P = .01186).
CONCLUSIONS:
The TSP-9 test outperformed the pathologists in risk stratifying patients with BE with LGD. Care guided by the test can provide an effective solution to variable pathology review of LGD, improving health outcomes by upstaging care to therapeutic intervention for patients at high risk for progression, while reducing unnecessary interventions in low-risk patients
Childhood traumatic experiences and mental health problems in sexually offending and non-sexually offending juveniles
OBJECTIVE: To examine the relationship between a history of childhood abuse and mental health problems in juveniles who sexually offended (JSOs) over and above general offending behavior.
METHODS: A sample of 44 JSOs incarcerated in two juvenile detention centers in the Netherlands between May 2008 and March 2014 were examined for childhood abuse history (Childhood Trauma Questionnaire-Short Form) and mental health problems (Massachusetts Youth Screening Instrument-Version 2). Furthermore, the connection between childhood abuse and mental health problems in JSOs was compared to a sample of 44 propensity score matched juveniles who offended non-sexually (non-JSOs).
RESULTS: In JSOs, sexual abuse was related to anger problems, suicidal ideation, and thought disturbance. These associations were significantly stronger in JSOs than in non-JSOs.
CONCLUSIONS: Our results suggest that the relationship between childhood abuse and both internalizing and externalizing mental health problems is of more salience for understanding sexual offending than non-sexual offending, and should, therefore, be an important focus in the assessment and treatment of JSOs
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