Dynnikov coordinates on virtual braid groups

We define Dynnikov coordinates on virtual braid groups. We prove that they are faithful invariants of virtual 2-braids, and present evidence that they are also very powerful invariants for general virtual braids

Cognitive improvement in patients with carotid stenosis is independent of treatment type

Treatment of carotid artery stenosis decreases the long-term risk of stroke and may enhance cerebral blood flow. It is therefore expected to have the potential to prevent cognitive decline or even improve cognition over the long-term. However, intervention itself can cause peri-interventional cerebral infarcts, possibly resulting in a decline of cognitive performance, at least for a short time. We investigated the long-term effects of three treatment methods on cognition and the emotional state one year after intervention. In this prospective observational cohort study, 58 patients with extracranial carotid artery stenosis (≥ 70%) underwent magnetic resonance imaging and assessment of cognition, mood and motor speed before carotid endarterectomy (n = 20), carotid stenting (n = 10) or best medical treatment (n = 28) (i.e., time-point 1 [TP1]), and at one-year follow-up (TP2). Gain scores, reflecting cognitive change after treatment, were built according to performance as (TP2 -TP1)/TP1. Independent of the treatment type, significant improvement in frontal lobe functions, visual memory and motor speed was found. Performance level, motor speed and mood at TP1 were negatively correlated with gain scores, with greater improvement in patients with low performance before treatment. Active therapy, whether conservative or interventional, produces significant improvement of frontal lobe functions and memory in patients with carotid artery disease, independent of treatment type. This effect was particularly pronounced in patients with low cognitive performance prior to treatment

Changes in life satisfaction when losing one's spouse: individual differences in anticipation, reaction, adaptation and longevity in the German Socio-economic Panel Study (SOEP)

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Losing a spouse is among the most devastating events that may occur in people's lives. We use longitudinal data from 1,224 participants in the German Socio-economic Panel Study (SOEP) to examine (a) how life satisfaction changes with the experience of spousal loss; (b) whether socio-demographic factors and social and health resources moderate spousal loss-related changes in life satisfaction; and (c) whether extent of anticipation, reaction and adaptation to spousal loss are associated with mortality. Results reveal that life satisfaction shows anticipatory declines about two and a half years prior to (anticipation), steep declines in the months surrounding (reaction) and lower levels after spousal loss (adaptation). Older age was associated with steeper anticipatory declines, but less steep reactive declines. Additionally, younger age, better health, social participation and poorer partner health were associated with better adaptation. Higher pre-loss life satisfaction, less steep reactive declines and better adaptation were associated with longevity. The discussion focuses on the utility of examining the interrelatedness among anticipation, reaction and adaptation to further our understanding of change in life satisfaction in the context of major life events

Identifying Ligand Binding Conformations of the β2-Adrenergic Receptor by Using Its Agonists as Computational Probes

Recently available G-protein coupled receptor (GPCR) structures and biophysical studies suggest that the difference between the effects of various agonists and antagonists cannot be explained by single structures alone, but rather that the conformational ensembles of the proteins need to be considered. Here we use an elastic network model-guided molecular dynamics simulation protocol to generate an ensemble of conformers of a prototypical GPCR, β2-adrenergic receptor (β2AR). The resulting conformers are clustered into groups based on the conformations of the ligand binding site, and distinct conformers from each group are assessed for their binding to known agonists of β2AR. We show that the select ligands bind preferentially to different predicted conformers of β2AR, and identify a role of β2AR extracellular region as an allosteric binding site for larger drugs such as salmeterol. Thus, drugs and ligands can be used as "computational probes" to systematically identify protein conformers with likely biological significance. © 2012 Isin et al

First direct detection of an exoplanet by optical interferometry; Astrometry and K-band spectroscopy of HR8799 e

To date, infrared interferometry at best achieved contrast ratios of a few times $10^{-4}$ on bright targets. GRAVITY, with its dual-field mode, is now capable of high contrast observations, enabling the direct observation of exoplanets. We demonstrate the technique on HR8799, a young planetary system composed of four known giant exoplanets. We used the GRAVITY fringe tracker to lock the fringes on the central star, and integrated off-axis on the HR8799e planet situated at 390 mas from the star. Data reduction included post-processing to remove the flux leaking from the central star and to extract the coherent flux of the planet. The inferred K band spectrum of the planet has a spectral resolution of 500. We also derive the astrometric position of the planet relative to the star with a precision on the order of 100$\,\mu$as. The GRAVITY astrometric measurement disfavors perfectly coplanar stable orbital solutions. A small adjustment of a few degrees to the orbital inclination of HR 8799 e can resolve the tension, implying that the orbits are close to, but not strictly coplanar. The spectrum, with a signal-to-noise ratio of $\approx 5$ per spectral channel, is compatible with a late-type L brown dwarf. Using Exo-REM synthetic spectra, we derive a temperature of $1150\pm50$\,K and a surface gravity of $10^{4.3\pm0.3}\,$cm/s$^{2}$. This corresponds to a radius of $1.17^{+0.13}_{-0.11}\,R_{\rm Jup}$ and a mass of $10^{+7}_{-4}\,M_{\rm Jup}$, which is an independent confirmation of mass estimates from evolutionary models. Our results demonstrate the power of interferometry for the direct detection and spectroscopic study of exoplanets at close angular separations from their stars.Comment: published in A&

Selecting feasible trajectories for robot-based X-ray tomography by varying focus-detector-distance in space restricted environments

Computed tomography has evolved as an essential tool for non-destructive testing within the automotive industry. The application of robot-based computed tomography enables high-resolution CT inspections of components exceeding the dimensions accommodated by conventional systems. However, large-scale components, e.g. vehicle bodies, often exhibit trajectory-limiting elements. The utilization of conventional trajectories with constant Focus-Detector-Distances can lead to anisotropy in image data due to the inaccessibility of some angular directions. In this work, we introduce two approaches that are able to select suitable acquisitions point sets in scans of challenging to access regions through the integration of projections with varying Focus-Detector-Distances. The variable distances of the X-ray hardware enable the capability to navigate around collision structures, thus facilitating the scanning of absent angular directions. The initial approach incorporates collision-free viewpoints along a spherical trajectory, preserving the field of view by maintaining a constant ratio between the Focus-Object-Distance and the Object-Detector-Distance, while discreetly extending the Focus-Detector-Distance. The second methodology represents a more straightforward approach, enabling the scanning of angular sectors that were previously inaccessible on the conventional circular trajectory by circumventing the X-ray source around these collision elements. Both the qualitative and quantitative evaluations, contrasting classical trajectories characterized by constant Focus-Detector-Distances with the proposed techniques employing variable Focus-Detector-Distances, indicate that the developed methods improve the object structure interpretability for scans of limited accessibility

Trajectory optimization for few-view robot-based CT: transitioning from static to object-specific acquisition geometries

The advent of robot-based computed tomography systems accelerated the development of trajectory optimization methodologies, with the objective of achieving superior image quality compared to standard trajectories while maintaining the same or even fewer number of required projections. The application of standard trajectories is not only inefficient due to the lack of integration of available prior knowledge about the object under investigation but also suboptimal because of limited accessibility issues during scans of large components, which are common in robot-based computed tomography. In this work, we introduce an object-specific trajectory optimization technique for few-view applications, based on a 3D Radon space analysis using a RANSAC algorithm. In contrast to existing methods, this approach allows for object geometry specific projection views, which are no longer constrained by discretized initial view sets on predefined acquisition geometries. In addition to eliminating the effects of discretized initial sets, this technique offers a distinct advantage in scenarios of limited accessibility by enabling the avoidance of collision elements, unlike trajectory optimizations on predefined acquisition geometries and standard trajectories. Our results show that the presented technology outperforms standard trajectories of evenly distributed projection views on predefined geometries in both ideal accessibility and limited accessibility scenarios. According to the employed geometry-based image quality metrics, our approach allows for reductions of more than 50 % in the number of projection views while maintaining equivalent image quality

The impact of positive psychological interventions on well-being in healthy elderly people

This systematic review aims to evaluate the impact of Positive Psychological Interventions (PPIs) on well-being in healthy older adults. Systematic review of PPIs obtained from three electronic databases (PsycINFO, Scopus, and Web of Science) was undertaken. Inclusion criteria were: that they were positive psychology intervention, included measurement of well-being, participants were aged over 60 years, and the studies were in English. The Cochrane Collaboration Guidelines dimensions of quality control, randomization, comparability, follow-up rate, dropout, blinding assessors are used to rate the quality of studies by two reviewers independently. The RE-AIM (Reach, Efficacy, Adoption, Implementation, and Maintenance) for evaluation of PPIs effectiveness was also applied. The final review included eight articles, each describing a positive psychological intervention study. The reminiscence interventions were the most prevalent type of PPIs to promote and maintain well-being in later life. Only two studies were rated as high quality, four were of moderate-quality and two were of low-quality. Overall results indicated that efficacy criteria (89%), reach criteria (85%), adoption criteria (73%), implementation criteria (67%), and maintenance criteria (4%) across a variety of RE-AIM dimensions. Directions for future positive psychological research related to RE-AIM, and implications for decision-making, are described