296 research outputs found
Space‐time PU‐DWR error control and adaptivity for the heat equation
In this work, space-time goal-oriented a posteriori error estimation using a partition-of-unity localization is applied to the linear heat equation. The algorithmic developments are substantiated with a numerical example
Numerical modeling and open-source implementation of variational partition-of-unity localizations of space-time dual-weighted residual estimators for parabolic problems
In this work, we consider space-time goal-oriented a posteriori error
estimation for parabolic problems. Temporal and spatial discretizations are
based on Galerkin finite elements of continuous and discontinuous type. The
main objectives are the development and analysis of space-time estimators, in
which the localization is based on a weak form employing a partition-of-unity.
The resulting error indicators are used for temporal and spatial adaptivity.
Our developments are substantiated with several numerical examples.Comment: Changes in v2: - Updated the title - Reworked space-time function
spaces - Added cG(1) in time partition-of-unity - Added links to the now
published codes used for this work - Added further reference
Single-protein optical holography
Light scattering by nanoscale objects is a fundamental physical property defined by their scattering cross-section and thus polarisability. Over the past decade, a number of studies have demonstrated single-molecule sensitivity by imaging the interference between coherent scattering from the object of interest and a reference field. This approach has enabled mass measurement of single biomolecules in solution owing to the linear scaling of the image contrast with the molecular polarisability. Nevertheless, all implementations to date are based on a common-path interferometer and cannot separate and independently tune the reference and scattered light field, thus prohibiting access to the rich toolbox available to holographic imaging. Here, we demonstrate comparable sensitivity using a non-common path geometry based on a dark-field scattering microscope, similar to a Mach-Zehnder interferometer. We separate the scattering and reference light into four parallel, inherently phase stable detection channels, delivering a five orders of magnitude boost in sensitivity in terms of scattering cross-section over state-of-the-art holographic methods. We demonstrate the detection, resolution and mass measurement of single proteins with mass below 100 kDa. Separate amplitude and phase measurement also yields direct information on sample identity and experimental determination of the polarisability of single biomolecules
Lexical alignment in triadic communication
Foltz A, Gaspers J, Thiele K, Stenneken P, Cimiano P. Lexical alignment in triadic communication. Frontiers in Psychology. 2015;6: 127
Frequency Scaling as a Security Threat on Multicore Systems
Most modern processors use Dynamic Voltage and Frequency Scaling (DVFS) for power management. DVFS allows to optimize power consumption by scaling voltage and frequency depending on performance demand. Previous research has indicated that this frequency scaling might pose a security threat in the form of a covert channel, which could leak sensitive information. However, an analysis able to determine whether DVFS is a serious security issue is still missing.
In this paper, we conduct a detailed analysis of the threat potential of a DVFS-based covert channel. We investigate two multicore platforms representative of modern laptops and hand-held devices. Furthermore, we develop a channel model to determine an upper bound to the channel capacity, which is in the order of 1 bit per channel use. Last, we perform an experimental analysis using a novel transceiver implementation. The neural network based receiver yields packet error rates between 1% and 8% at average throughputs of up to 1.83 and 1.20 bits per second for platforms representative of laptops and hand-held devices, respectively. Considering the well-known small message criterion, our results show that a relevant covert channel can be established by exploiting the behaviour of computing systems with DVFS.ISSN:0278-0070ISSN:1937-415
The inter-individual anatomical variation of the trochlear notch as a predisposition for simple elbow dislocation
Purpose: Besides the multi-layered capsule-ligamentous complex of the elbow joint the high bony congruence in the ulnohumeral joint contributes to elbow stability. Therefore, we assume that specific anatomical configurations of the trochlear notch predispose to dislocation. In case of ligamentous elbow dislocation both conservative and surgical treatment is possible without a clear treatment algorithm. Findings of constitutional bony configurations could help deciding for the best treatment option.
Methods: In this retrospective matched-pair analysis we compared MRI imaging from patients sustaining a primary traumatic elbow dislocation (instability group) with patients suffering from chronic lateral epicondylitis (control group), treated between 2009 and 2019. Two independent observers measured different anatomical landmarks of the trochlear notch in a multiplanar reconstructed standardized sagittal trochlear plane (SSTP). Primarily, opening angle and relative depth of the trochlear notch were determined. After adjustment to the proximal ulnar rim in the SSTP, coronoid and olecranon angle, the articular angle as well as the ratio of the tip heights of the trochlear notch were measured.
Results: We compared 34 patients in the instability group (age 48 +/- 14 years, f/m 19/15) with 34 patients in the control group (age 47 +/- 16 years, f/m 19/15). Instability group showed a significantly larger opening angle (94.1 degrees +/- 6.9 degrees vs. 88.5 degrees +/- 6.9 degrees, p = 0.0002), olecranon angle (60.9 degrees +/- 5.3 degrees vs. 56.1 degrees +/- 5.1 degrees, p < 0.0001) and articular angle (24.7 degrees +/- 6.4 degrees vs. 22.3 degrees +/- 5.8 degrees, p = 0.02) compared to the control group. Measuring the height from the coronoid (ch) and olecranon (oh) tip also revealed a significantly larger tip ratio (tr = ch/oh) in the instability group (2.7 +/- 0.8 vs. 2.2 +/- 0.5, p < 0.0001). The relative depth (61.0% +/- 8.3% vs. 62.7% +/- 6.0%, p = 0.21) of the trochlear notch as well as the coronoid angle (32.8 degrees +/- 4.5 degrees vs. 31.7 degrees +/- 5.2 degrees, p = 0.30) showed no significant difference in the instability group compared to the control group. The interrater reliability of all measurements was between 0.83 and 0.94.
Conclusion: MRI of patients with elbow dislocation show that there seems to be a bony anatomical predisposition. According to the results, it seems reasonable to include predisposing bony factors in the decision-making process when surgical stabilization and conservative treatment is possible. Further biomechanical studies should prove these assumptions to generate critical bony values helping surgeons with decision making
Dissecting Calcific Aortic Valve Disease—The Role, Etiology, and Drivers of Valvular Fibrosis
Calcific aortic valve disease (CAVD) is a highly prevalent and progressive disorder
that ultimately causes gradual narrowing of the left ventricular outflow orifice with
ensuing devastating hemodynamic effects on the heart. Calcific mineral accumulation
is the hallmark pathology defining this process; however, fibrotic extracellular matrix
(ECM) remodeling that leads to extensive deposition of fibrous connective tissue
and distortion of the valvular microarchitecture similarly has major biomechanical and
functional consequences for heart valve function. Significant advances have been made
to unravel the complex mechanisms that govern these active, cell-mediated processes,
yet the interplay between fibrosis and calcification and the individual contribution to
progressive extracellular matrix stiffening require further clarification. Specifically, we
discuss (1) the valvular biomechanics and layered ECM composition, (2) patterns
in the cellular contribution, temporal onset, and risk factors for valvular fibrosis, (3)
imaging valvular fibrosis, (4) biomechanical implications of valvular fibrosis, and (5)
molecular mechanisms promoting fibrotic tissue remodeling and the possibility of reverse
remodeling. This review explores our current understanding of the cellular and molecular
drivers of fibrogenesis and the pathophysiological role of fibrosis in CAVD
Transcriptomic Research in Heart Failure with Preserved Ejection Fraction: Current State and Future Perspectives
Heart failure with preserved ejection fraction (HFpEF) is increasing in incidence and has a higher prevalence compared with heart failure with reduced ejection fraction. So far, no effective treatment of HFpEF is available, due to its complex underlying pathophysiology and clinical heterogeneity. This article aims to provide an overview and a future perspective of transcriptomic biomarker research in HFpEF. Detailed characterisation of the HFpEF phenotype and its underlying molecular pathomechanisms may open new perspectives regarding early diagnosis, improved prognostication, new therapeutic targets and tailored therapies accounting for patient heterogeneity, which may improve quality of life. A combination of cross-sectional and longitudinal study designs with sufficiently large sample sizes are required to support this concept
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