De complexiteit van de sociale verzekering

Society; Social Science

Time-varying effective EEG source connectivity: the optimization of model parameters*

Adaptive estimation methods based on general Kalman filter are powerful tools to investigate brain networks dynamics given the non-stationary nature of neural signals. These methods rely on two parameters, the model order p and adaptation constant c, which determine the resolution and smoothness of the time-varying multivariate autoregressive estimates. A sub-optimal filtering may present consistent biases in the frequency domain and temporal distortions, leading to fallacious interpretations. Thus, the performance of these methods heavily depends on the accurate choice of these two parameters in the filter design. In this work, we sought to define an objective criterion for the optimal choice of these parameters. Since residual- and information-based criteria are not guaranteed to reach an absolute minimum, we propose to study the partial derivatives of these functions to guide the choice of p and c. To validate the performance of our method, we used a dataset of human visual evoked potentials during face perception where the generation and propagation of information in the brain is well understood and a set of simulated data where the ground truth is available

Atomic force microscopy applications in macromolecular crystallography

Atomic force microscopy (AFM) can be applied both in situ and ex situ to study the growth of crystals from solution. The method is particularly useful for investigating the crystallization of proteins, nucleic acids and viruses because it can be carried out in the mother liquor and in a non-perturbing fashion. Interactions and transformations between various growth mechanisms can be directly visualized as a function of supersaturation, as can the incorporation of diverse impurities and the formation and propagation of defects. Because the crystals can be observed over long periods, it is also possible to obtain precise quantitative measures of the kinetic parameters for nucleation and growth. Finally, AFM has allowed us to identify a number of previously unsuspected phenomena that influence nucleation, rate of growth and the ultimate perfection of macromolecular crystals. These are all features which are important in determining the ultimate resolution and quality of a crystal's diffraction pattern

Nonlinear Dynamics of the Perceived Pitch of Complex Sounds

We apply results from nonlinear dynamics to an old problem in acoustical physics: the mechanism of the perception of the pitch of sounds, especially the sounds known as complex tones that are important for music and speech intelligibility

A Translational Model for Repeated Episodes of Joint Inflammation : Welfare, Clinical and Synovial Fluid Biomarker Assessment

This study investigates repeated low-dose lipopolysaccharide (LPS) injections in equine joints as a model for recurrent joint inflammation and its impact on animal welfare. Joint inflammation was induced in eight horses by injecting 0.25 ng of LPS three times at two-week intervals. Welfare scores and clinical parameters were recorded at baseline and over 168 h post-injection. Serial synoviocentesis was performed for the analysis of a panel of synovial fluid biomarkers of inflammation and cartilage turnover. Clinical parameters and a final synoviocentesis were also performed eight weeks after the last sampling point to assess the recovery of normal joint homeostasis. Statistical methods were used to compare the magnitude of response to each of the 3 LPS inductions and to compare the baseline and final measurements. Each LPS injection produced consistent clinical and biomarker responses, with minimal changes in welfare scores. General matrix metalloproteinase (MMP) activity and joint circumference showed greater response to the second LPS induction, but response to the third was comparable to the first. Gylcosaminoglycans (GAG) levels showed a significantly decreased response with each induction, while collagen-cleavage neoepitope of type II collagen (C2C) and carboxypropetide of type II collagen epitope (CPII) showed quicker responses to the second and third inductions. All parameters were comparable to baseline values at the final timepoint. In conclusion, a consistent, reliable intra-articular inflammatory response can be achieved with repeated injections of 0.25 ng LPS, with minimal impact on animal welfare, suggesting potential as a refined translational model of recurrent joint inflammation

Schatten van grasopbrengst op basis van spectrale reflectie, grashoogte en modellering : Onderzoeksresultaten van een maaiproef op zand- klei en veengrond 2016-2017

For dairy farmers a good estimate of the current grass yield is essential for grassland planning. To see to what extent grass yield and nitrogen content can be measured with remote sensing, spectral reflection measurements were compared in a field trial with dry matter yields and nitrogen content of mown grass (‘ground truth’ data). These yields and contents were also used to validate a model-based estimate of the grass yield and the nitrogen content or crude protein content. A practical comparison has also been made with grass height measurements. Reflection measurements gave a rough estimate of the dry matter yield. By making a distinction between location and by including basic growth data, the estimate improved considerably. A model-based growth prediction gave a better estimate of the dry matter yield and improved even further in combination with reflection measurements or grass height. With the current techniques, nitrogen content of grass appears to be difficult to measure and predict

Contemporary use of devices in chronic heart failure in the Netherlands

Aims: Despite previous surveys regarding device implantation rates in heart failure (HF), insight into the real-world management with devices is scarce. Therefore, we investigated device implantation rates in HF with reduced left ventricular ejection fraction (LVEF) in 34 Dutch centres. Methods and results: A cross-sectional outpatient registry was conducted in 6666 patients with LVEF < 50% and with information about device implantation available [74 (66–81) years of age; 64% male]. Patients were classified into conventional pacemakers (PM, n = 562), implantable cardioverter defibrillato

Mesoporous silica formation mechanisms probed using combined Spin-Echo Modulated Small Angle Neutron Scattering (SEMSANS) and Small Angle Neutron Scattering (SANS)

International audienceThe initial formation stages of surfactant-templated silica thin films which grow at the air−water interface were studied using combined spin−echo modulated small-angle neutron scattering (SEMSANS) and small-angle neutron scattering (SANS). The films are formed from either a cationic surfactant or nonionic surfactant (C16EO8) in a dilute acidic solution by the addition of tetramethoxysilane. Previous work has suggested a twostage formation mechanism with mesostructured particle formation in the bulk solution driving film formation at the solution surface. From the SEMSANS data, it is possible to pinpoint accurately the time associated with the formation of large particles in solution that go on to form the film and to show their emergence is concomitant with the appearance of Bragg peaks in the SANS pattern, associated with the two-dimensional hexagonal order. The combination of SANS and SEMSANS allows a complete depiction of the steps of the synthesis that occur in the subphase