Numerical simulations of possible finite time singularities in the incompressible Euler equations: comparison of numerical methods

The numerical simulation of the 3D incompressible Euler equation is analyzed with respect to different integration methods. The numerical schemes we considered include spectral methods with different strategies for dealiasing and two variants of finite difference methods. Based on this comparison, a Kida-Pelz like initial condition is integrated using adaptive mesh refinement and estimates on the necessary numerical resolution are given. This estimate is based on analyzing the scaling behavior similar to the procedure in critical phenomena and present simulations are put into perspective.Comment: Euler equations: 250 years o

Neuropsychological Sequelae of Carotid Angioplasty with Stent Placement: Correlation with Ischemic Lesions in Diffusion Weighted Imaging

BACKGROUND AND PURPOSE: Few studies investigated the neuropsychological outcome after carotid angioplasty with stent placement (CAS), yielding partially inconsistent results. The present investigation evaluated the effect of CAS in patients with high-grade stenosis and assessed the predictive value of ischemic lesion number for postinterventional cognitive deterioration. METHODS: 22 patients were tested neuropsychologically before and six weeks after CAS. Cerebral ischemic changes were assessed with diffusion weighted imaging (DWI) prior to and after angioplasty. RESULTS: Pre- to postinterventional cognitive performance improved significantly in terms of verbal memory (t = -2.30; p<0.05), whereas significant deterioration was noted regarding verbal memory span (t = 2.31; p<0.05). 8 (36%) persons conformed to the criteria of cognitive improvement. 6 patients (27%) were postinterventionally classified as having deficits. Analysis yielded no statistically significant correlations between lesion quantity and cognitive change. CONCLUSION: Both improvement and deterioration of cognitive functioning was observed in our collective of patients, leaving the neuropsychological outcome after percutaneous transluminal angioplasty unpredictable in individual cases. The presence of acute ischemic lesions on DWI was found to be not tightly associated with cognitive dysfunction after CAS

On the cardiorespiratory coordination assessed by the photoplethysmography imaging technique

Abstract Cardiorespiratory coordination (CRC) probes the interaction between cardiac and respiratory oscillators in which cardiac and respiratory activity are synchronized, with individual heartbeats occurring at approximately the same temporal positions during several breathing cycles. An increase of CRC has previously been related to pathological stressful states. We studied CRC employing coordigrams computed from non-contact photoplethysmography imaging (PPGI) and respiratory data using the optical flow method. In a blocked study design, we applied the cold pressure test (CPT), water at ambient temperature (AWT), and intermittent resting conditions. In controls (no intervention), CRC remained on initial low levels throughout measurements. In the experimental group (AWT and CPT intervention), CRC decreased during AWT and CPT. Following both interventions, CRC increased significantly, with a rebound effect following AWT. In controls, HR increased steadily over time. CPT evoked a significant HR increase which correlated with subjective stress/pain ratings. The CRC increase following AWT correlated significantly with subjective pain (r = .79) and stress (r = .63) ratings. Furthermore, we observed a significant correlation (r = − .80) between mean RMSSD and mean duration of CRC, which further supports an association between autonomic state and CRC level. CRC analysis obtained from cutaneous tissue perfusion data therefore appears to be a sensitive and useful method for the study of CRC and ANS activity. Future studies need to investigate the physiological principles and clinical significance of these findings

Autonomic nervous system responses in the intermediate band to cranial cutaneous stimulation

Abstract Cardiovascular rhythms representing functional states of the autonomic nervous system (ANS) are insufficiently reflected by the current physiological model based on low and high frequency bands (LF, HF, resp.). An intermediate (IM) frequency band generated by a brainstem pacemaker was included in systemic physiological ANS analyses of forehead skin perfusion (SP), ECG, and respiration. Data of 38 healthy participants at T0 and T1 (+1 week) before, during, and following osteopathic cranial vault hold (CVH) stimulation were analyzed including momentary frequencies of highest amplitude, amplitudes in low (0.05–0.12 Hz), IM (0.12–0.18 Hz), and high (0.18–0.4 Hz) frequency bands, and established heart rate variability (HRV) metrics. During CVH, LF interval durations increased, whereas IM/HF band durations decreased significantly. Amplitudes increased significantly in all frequency bands. A cluster analysis found one response pattern dominated by IM activity (47% of participants) with highly stable 0.08 Hz oscillation to CVH, and one dominated by LF activity (0.10 Hz) at T0, increasing to IM activity at T1. Showing frequency ratios at ≈3:1, respiration was not responsible for oscillations in PPG during CVH. HRV revealed no significant responses. Rhythmic patterns in SP and respiration matched previous findings on a reticular “0.15 Hz rhythm”. Involvement of baroreflex pathways is discussed as alternative explanation

Structural basis of assembly chaperone-mediated snRNP formation

Small nuclear ribonucleoproteins (snRNPs) represent key constituents of major and minor spliceosomes. snRNPs contain a common core, composed of seven Sm proteins bound to snRNA, which forms in a step-wise and factor-mediated reaction. The assembly chaperone pICln initially mediates the formation of an otherwise unstable pentameric Sm protein unit. This so-called 6S complex docks subsequently onto the SMN complex, which removes pICln and enables the transfer of pre-assembled Sm proteins onto snRNA. X-ray crystallography and electron microscopy was used to investigate the structural basis of snRNP assembly. The 6S complex structure identifies pICln as an Sm protein mimic, which enables the topological organization of the Sm pentamer in a closed ring. A second structure of 6S bound to the SMN complex components SMN and Gemin2 uncovers a plausible mechanism of pICln elimination and Sm protein activation for snRNA binding. Our studies reveal how assembly factors facilitate formation of RNA-protein complexes in vivo

Data publication: An approach for in situ fouling monitoring in heat exchangers using electrical impedance spectroscopy

The dataset presented in this study is focused on the in situ monitoring of organic fouling in a plate heat exchanger using electrical impedance spectroscopy (EIS). The primary objective was to accurately determine the thickness of fouling layers that develop over time during heat exchanger operation. The experiments were conducted using an impedance analyzer (Sciospec ISX-3) configured in a four-terminal setup with two electrodes. The counter and reference electrodes were connected to a probe positioned at the top of the chamber, while the working and sensing electrodes were connected to the heating plate of the heat exchanger. This configuration allowed for the precise measurement of impedance across the fouling layer. The amplitude of the excitation signal was set to 1 V (rms). This value was chosen to maintain linearity at high frequencies and to ensure a high signal-to-noise ratio (SNR). The impedance spectra were recorded across a frequency range of 10 Hz to 2 MHz. The spectrum included 50 measurement points that were logarithmically spaced within this range to capture detailed impedance characteristics across different frequencies. Impedance data were sampled at a rate of 45 mHz, and measurements were collected over a duration of approximately 600 minutes, allowing for continuous monitoring of the fouling development process. The raw data consists of impedance measurements, reflecting changes in the electrical properties of the fouling layer as it accumulates on the heat exchanger surfaces. The data points in the spectrum provide insights into the relationship between fouling thickness and impedance across various frequencies, which is critical for developing models to predict fouling behavior in heat exchangers.This dataset is valuable for researchers and engineers interested in non-invasive fouling monitoring techniques, offering a foundation for improving heat exchanger efficiency through real-time fouling detection and characterization

PolyQ-expanded ataxin-3 protein levels in peripheral blood mononuclear cells correlate with clinical parameters in SCA3: a pilot study

In view of upcoming clinical trials, quantitative molecular markers accessible in peripheral blood are of critical importance as prognostic or pharmacodynamic markers in genetic neurodegenerative diseases such as Spinocerebellar Ataxia Type 3 (SCA3), in particular for signaling target engagement. In this pilot study, we focused on the quantification of ataxin-3, the protein altered in SCA3, in human peripheral blood mononuclear cells (PBMCs) acquired from preataxic and ataxic SCA3 mutation carriers as well as healthy controls, as a molecular marker directly related to SCA3 pathophysiology. We established two different highly sensitive TR-FRET-based immunoassays to measure the protein levels of either total full-length, non-expanded and expanded, ataxin-3 or specifically polyQ-expanded ataxin-3. In PBMCs, a clear discrimination between SCA3 mutation carrier and controls were seen measuring polyQ-expanded ataxin-3 protein level. Additionally, polyQ-expanded ataxin-3 protein levels correlated with disease progression and clinical severity as assessed by the Scale for the Assessment and Rating of Ataxia. Total full-length ataxin-3 protein levels were directly influenced by the expression levels of the polyQ-expanded ataxin-3 protein, but were not correlated with clinical parameters. Assessment of ataxin-3 levels in fibroblasts or induced pluripotent stem cells allowed to distinguish mutation carriers from controls, thus providing proof-of-principle validation of our PBMC findings across cell lines. Total full-length or polyQ-expanded ataxin-3 protein was not detectable by TR-FRET assays in other biofluids like plasma or cerebrospinal fluid, indicating the need for ultra-sensitive assays for these biofluids. Standardization studies revealed that tube systems, blood sampling, and PBMC preparation may influence ataxin-3 protein levels indicating a high demand for standardized protocols in biomarker studies. In conclusion, the polyQ-expanded ataxin-3 protein is a promising candidate as a molecular target engagement marker in SCA3 in future clinical trials, determinable even in-easily accessible-peripheral blood biomaterials. These results, however, require validation in a larger cohort and further standardization of modifying conditions