Magnetic resonance angiography signal intensity as a marker of hemodynamic impairment in intracranial arterial stenosis.

BackgroundIntracranial arterial stenosis (ICAS) is the predominant cause of ischemic stroke and transient ischemic attack in Asia. Change of signal intensities (SI) across an ICAS on magnetic resonance angiography (MRA) may reflect its hemodynamic severity.MethodsIn-patients with a symptomatic single ICAS detected on 3D time-of-flight MRA were recruited from 2 hospitals. Baseline and 1-year follow-up data were collected. Signal intensity ratio (SIR) [ =  (mean post-stenotic SI -mean background SI)/(mean pre-stenotic SI - mean background SI)] was evaluated on baseline MRA to represent change of SIs across an ICAS. Acute infarct volume was measured on baseline diffusion-weighted images (DWI). Relationships between SIR and baseline characteristics as well as 1y outcomes were evaluated.ResultsThirty-six subjects (86.1% males, mean age 55.0) were recruited. Overall, mean SIR was 0.84±0.23. Mean SIRs were not significantly different between the 23 (63.9%) anatomically severe stenoses and the 13 (36.1%) anatomically moderate stenoses (0.80±0.23 versus 0.92±0.21, p = 0.126). SIR was significantly, linearly and negatively correlated to acute infarct volume on DWI (Spearman correlation coefficient -0.471, p = 0.011). Two patients (5.6%) had recurrent ischemic strokes at 1y, not related to SIR values.ConclusionsChange of signal intensities across an ICAS on MRA may reflect its hemodynamic and functional severity. Future studies are warranted to further verify the relationships between this index and prognosis of patients with symptomatic ICAS

Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite

As China's first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band (1-250 keV) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 MeV. It was designed to perform pointing, scanning and gamma-ray burst (GRB) observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed. Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results.Comment: 29 pages, 40 figures, 6 tables, to appear in Sci. China-Phys. Mech. Astron. arXiv admin note: text overlap with arXiv:1910.0443

La mesure de probabilité génératrice de données dans le pire des cas

In this paper, the worst-case probability measure over the data is introduced as a tool for characterizing the generalization capabilities of machine learning algorithms. More specifically, the worst-case probability measure is a Gibbs probability measure and the unique solution to the maximization of the expected loss under a relative entropy constraint with respect to a reference probability measure. Fundamental generalization metrics, such as the sensitivity of the expected loss, the sensitivity of the empirical risk, and the generalization gap are shown to have closed-form expressions involving the worst-case data-generating probability measure. Existing results for the Gibbs algorithm, such as characterizing the generalization gap as a sum of mutual information and lautum information, up to a constant factor, are recovered. A novel parallel is established between the worst-case data-generating probability measure and the Gibbs algorithm. Specifically, the Gibbs probability measure is identified as a fundamental commonality of the model space and the data space for machine learning algorithms.Dans ce rapport, la mesure de probabilité du pire cas sur les données est présentée comme un outil pour caractériser les capacités de généralisation des algorithmes d'apprentissage automatique. Plus précisément, la mesure de probabilité du pire cas est une solution à la maximisation de la valeur espérée de la perte (ou risque) induite par un modèle sous une contrainte d'entropie relative par rapport à une mesure de probabilité de référence. Étant donné un modèle, le résultat central consiste en une expression explicite de la différence entre les valeurs espérées de la perte par rapport à deux mesures de probabilité quelconques sur l'ensemble de données. Cette différence est caractérisée en termes de ``distances statistiques'' mesurées via des divergences KL impliquant les mesures données; la mesure de référence; et la mesure de probabilité du pire cas. Lorsque les mesures données sont les types (mesures de probabilité empiriques) induits par deux ensembles de données, une expression sous forme fermée pour la différence entre les risques empiriques correspondants est obtenue. Enfin, l'écart de généralisation induit par un algorithme d'apprentissage quelconque est caractérisé. Les résultats existants pour l'algorithme de Gibbs, tels que l'égalité entre l'écart de généralisation et une somme d'informations mutuelles et d'informations de lautum, à un facteur constant près, sont récupérés. Tout ce qui précède suggère une dualité entre l'algorithme de Gibbs et la mesure du pire cas au-delà du fait que les deux sont représentés par des mesures de probabilité de Gibbs

Anti-inflammatory effect of IL-1ra-loaded dextran/PLGA microspheres on Porphyromonas gingivalis lipopolysaccharide-stimulated macrophages in vitro and in vivo in a rat model of periodontitis

Periodontitis is a multifactorial chronic infectious disease leading to a host immune response involving inflammatory cytokines, especially IL-1β, which is the main reason for further developing this disease. IL-1 receptor antagonist (IL-1ra) binds IL-1 receptor, inhibiting IL-1β signaling and reducing the levels of other cytokines closely related to periodontitis, such as IL-6 and TNF-α. Therefore, the use of IL-1ra to inhibit periodontitis development in a system, ensuring its sustained release, might be an effective way to combat this disease. Hence, in this study, a novel IL-1ra-loaded dextran/PLGA microsphere was developed to allow the sustained release of IL-1ra and enhance the anti-inflammatory properties. Therefore, this study’s purposes were to develop a novel periodontal treatment for inhibition and treatment of periodontitis and evaluate the sustained-release effect and anti-inflammatory properties of IL-1ra-loaded dextran/PLGA microspheres in vitro by cell experiments and in vivo by animal experiments. The results showed that IL-1ra-loaded dextran/PLGA microspheres were non-toxic both in vitro and in vivo and could be used as a safe and effective treatment. In addition, these microspheres could significantly prolong the half-life of IL-1ra drug, exerting a useful anti-inflammatory effect in macrophages stimulated with P. gingivalis lipopolysaccharide and in rats with periodontitis. In conclusion, IL-1ra-loaded dextran/PLGA microsphere might be a useful tool to combat periodontal disease

Switchable quantum anomalous and spin Hall effects in honeycomb magnet EuCd2As2

Creating and engineering the topological features of intrinsic magnets are essential for topological spintronic applications. Here, we propose a material platform to realize the switchable topological phase transition between quantum anomalous Hall (QAH) and quantum spin Hall (QSH) effects, unlike generally used magnetic doping, by strain engineering. At equilibrium lattice parameters, the QAH effect emerges in EuCd _2 As _2 quintuple layers with nonzero Chern number and chiral edge states. Accompanying a strain-engineered magnetic phase transition from out-of-plane ferromagnetic (FM) to in-plane antiferromagnetic (AFM) states, a topological phase transition is simultaneously achieved, resulting in the QSH effect, which is explicitly confirmed by nonzero spin Chern number and the emergence of gapless edge states, even without time-reversal symmetry. Remarkably, the obtained QSH effect is highly robust against the magnetic configurations, including FM and AFM configurations with both out-of-plane and in-plane directions, hereby promoting EuCd _2 As _2 as a wonderful candidate for understanding and utilizing the magnetic topological states in spintronics