Molecular Factors Influencing Retention on Immobilized Artificial Membranes (IAM) Compared to Partitioning in Liposomes and n -Octanol

Purpose. To assess the effect of molecular factors influencing retention on immobilized artificial membrane (IAM) high-performance liquid chromatography columns compared to liposomal partitioning and traditional n-octanol/water partition coefficients. Methods. IAM capacity factors were measured at pH 7.0 on an IAM.PC.DD2 stationary phase. Liposomal partitioning at pH 7.0 and n-octanol/water partition coefficients were measured using the pH metric method. Partitioning in egg-phosphatidylcholine (PhC) liposomes was also measured by equilibrium dialysis for a series of β-blockers. Results. For the ionized β-blockers, potentiometry and equilibrium dialysis yielded consistent partitioning data. For relatively large bases, IAM retention correlated well with PhC liposome partitioning, hydrophobic forces being mainly involved. For more hydrophilic compounds and for heterogeneous solutes, in contrast, the balance between electrostatic and hydrophobic interactions was not the same in the two systems. Hydrogen bonding, an important factor in liposomes partitioning, played only a minor role in IAM retention. Conclusions. Partitioning in immobilized artificial membranes depends on size, hydrophobicity, and charge. When hydrophobic interactions dominate retention, IAM capacity factors are well correlated with liposomal partitioning. On the contary, for hydrophilic solutes, the two systems do not yield the same information and are not interchangeabl

KiDS-1000 Cosmology: Constraints from density split statistics

Context. Weak lensing and clustering statistics beyond two-point functions can capture non-Gaussian information about the matter density field, thereby improving the constraints on cosmological parameters relative to the mainstream methods based on correlation functions and power spectra. Aims. This paper presents a cosmological analysis of the fourth data release of the Kilo Degree Survey based on the density split statistics, which measures the mean shear profiles around regions classified according to foreground densities. The latter is constructed from a bright galaxy sample, which we further split into red and blue samples, allowing us to probe their respective connection to the underlying dark matter density. Methods. We use the state-of-the-art model of the density splitting statistics and validate its robustness against mock data infused with known systematic effects such as intrinsic galaxy alignment and baryonic feedback. Results. After marginalising over the photometric redshift uncertainty and the residual shear calibration bias, we measure for the full KiDS-bright sample a structure growth parameter of $S_8 = \sigma_8 \sqrt{\Omega_\mathrm{m}/0.3} = 0.74^{+0.03}_{-0.02}$ that is competitive to and consistent with two-point cosmic shear results, a matter density of $\Omega_\mathrm{m} = 0.28 \pm 0.02$, and a constant galaxy bias of $b = 1.32^{+0.12}_{-0.10}$.Comment: 18 pages, 23 Figures. Submitted to A&

KiDS-450: cosmological constraints from weak-lensing peak statistics – II: Inference from shear peaks using N-body simulations

We study the statistics of peaks in a weak-lensing reconstructed mass map of the first 450 deg2 of the Kilo Degree Survey (KiDS-450). The map is computed with aperture masses directly applied to the shear field with an NFW-like compensated filter. We compare the peak statistics in the observations with that of simulations for various cosmologies to constrain the cosmological parameter S8=σ8Ωm/0.3−−−−−−√⁠, which probes the (Ωm, σ8) plane perpendicularly to its main degeneracy. We estimate S8 = 0.750 ± 0.059, using peaks in the signal-to-noise range 0 ≤ S/N ≤ 4, and accounting for various systematics, such as multiplicative shear bias, mean redshift bias, baryon feedback, intrinsic alignment, and shear–position coupling. These constraints are ∼ 25 per cent tighter than the constraints from the high significance peaks alone (3 ≤ S/N ≤ 4) which typically trace single-massive haloes. This demonstrates the gain of information from low-S/N peaks. However, we find that including S/N < 0 peaks does not add further information. Our results are in good agreement with the tomographic shear two-point correlation function measurement in KiDS-450. Combining shear peaks with non-tomographic measurements of the shear two-point correlation functions yields a ∼20 per cent improvement in the uncertainty on S8 compared to the shear two-point correlation functions alone, highlighting the great potential of peaks as a cosmological probe

KiDS-450: cosmological constraints from weak lensing peak statistics – I. Inference from analytical prediction of high signal-to-noise ratio convergence peaks

This paper is the first of a series of papers constraining cosmological parameters with weak lensing peak statistics using ∼ 450 deg2 of imaging data from the Kilo Degree Survey (KiDS-450). We measure high signal-to-noise ratio (SNR: ν) weak lensing convergence peaks in the range of 3 < ν < 5, and employ theoretical models to derive expected values. These models are validated using a suite of simulations. We take into account two major systematic effects, the boost factor and the effect of baryons on the mass–concentration relation of dark matter haloes. In addition, we investigate the impacts of other potential astrophysical systematics including the projection effects of large-scale structures, intrinsic galaxy alignments, as well as residual measurement uncertainties in the shear and redshift calibration. Assuming a flat Λ cold dark matter model, we find constraints for S8=σ8(Ωm/0.3)0.5=0.746+0.046−0.107S8=σ8(Ωm/0.3)0.5=0.746−0.107+0.046 according to the degeneracy direction of the cosmic shear analysis and Σ8=σ8(Ωm/0.3)0.38=0.696+0.048−0.050Σ8=σ8(Ωm/0.3)0.38=0.696−0.050+0.048 based on the derived degeneracy direction of our high-SNR peak statistics. The difference between the power index of S8 and in Σ8 indicates that combining cosmic shear with peak statistics has the potential to break the degeneracy in σ8 and Ωm. Our results are consistent with the cosmic shear tomographic correlation analysis of the same data set and ∼2σ lower than the Planck 2016 results

L'apprentissage de l'orthographe d'usage et ses troubles dans la dyslexie développementale de surface

Summary : Learning to spell words : Difficulties in developmental surface dyslexia. Word spelling performance of normal children from the first to the fifth grade was analysed and compared with the performance of children having a reading and spelling impairment characteristic of surface dyslexia. The quantitative analysis of their productions for word spelling to dictation showed that the performance of children with surface dyslexia was very similar to that of younger control children of the same reading level. The qualitative analysis of the erroneous spellings showed that for children with surface dyslexia, knowledge of the phonology-to-orthography correspondences was comparable to that of chronological-age-matched children. In contrast, the lexical knowledge of children with surface dyslexia was very poor and close to that of very beginning readers. The results suggest that the spelling deficit associated with developmental surface dyslexia results from a cognitive disorder that prevents the establishment of specific lexical spelling knowledge. Key words : spelling, development, surface dyslexia, surface dysgraphia, retardation vs deviance.Martinet Catherine, Valdois S. L'apprentissage de l'orthographe d'usage et ses troubles dans la dyslexie développementale de surface. In: L'année psychologique. 1999 vol. 99, n°4. pp. 577-622