Radiomics in Cross-Sectional Adrenal Imaging: A Systematic Review and Quality Assessment Study

In this study, we aimed to systematically review the current literature on radiomics applied to cross-sectional adrenal imaging and assess its methodological quality. Scopus, PubMed and Web of Science were searched to identify original research articles investigating radiomics applications on cross-sectional adrenal imaging (search end date February 2021). For qualitative synthesis, details regarding study design, aim, sample size and imaging modality were recorded as well as those regarding the radiomics pipeline (e.g., segmentation and feature extraction strategy). The methodological quality of each study was evaluated using the radiomics quality score (RQS). After duplicate removal and selection criteria application, 25 full-text articles were included and evaluated. All were retrospective studies, mostly based on CT images (17/25, 68%), with manual (19/25, 76%) and two-dimensional segmentation (13/25, 52%) being preferred. Machine learning was paired to radiomics in about half of the studies (12/25, 48%). The median total and percentage RQS scores were 2 (interquartile range, IQR = −5–8) and 6% (IQR = 0–22%), respectively. The highest and lowest scores registered were 12/36 (33%) and −5/36 (0%). The most critical issues were the absence of proper feature selection, the lack of appropriate model validation and poor data openness. The methodological quality of radiomics studies on adrenal cross-sectional imaging is heterogeneous and lower than desirable. Efforts toward building higher quality evidence are essential to facilitate the future translation into clinical practice

Interaction and flocculation of spherical colloids wetted by a surface-induced corona of paranematic order

Particles dispersed in a liquid crystal above the nematic-isotropic phase transition are wetted by a surface-induced corona of paranematic order. Such coronas give rise to pronounced two-particle interactions. In this article, we report details on the analytical and numerical study of these interactions published recently [Phys. Rev. Lett. 86, 3915 (2001)]. We especially demonstrate how for large particle separations the asymptotic form of a Yukawa potential arises. We show that the Yukawa potential is a surprisingly good description for the two-particle interactions down to distances of the order of the nematic coherence length. Based on this fact, we extend earlier studies on a temperature induced flocculation transition in electrostatically stabilized colloidal dispersions [Phys. Rev. E 61, 2831 (2000)]. We employ the Yukawa potential to establish a flocculation diagram for a much larger range of the electrostatic parameters, namely the surface charge density and the Debye screening length. As a new feature, a kinetically stabilized dispersion close to the nematic-isotropic phase transition is found.Comment: Revtex v4.0, 16 pages, 12 Postscript figures. Accepted for publication in Phys. Rev.

High-order power series expansion of the elastic interaction between conical membrane inclusions

We revisit the problem of the long-range interaction between two conical proteins inserted into a lipid membrane and interacting via the induced deformation of the membrane, first considered by Goulian et al. (M. Goulian, R. Bruinsma, P. Pincus, Europhys. Lett. 22, 145 (1993); Europhys. Lett. 23, 155 (1993)). By means of a complex variables formulation and an iterative solution, we determine analytically an arbitrary high-order expansion of the interaction energy in powers of the inverse distance between two inclusions of different sizes. At leading order and for inclusions of equal sizes, we recover the result obtained by Goulian et al.. We generalize the development to inclusions of different sizes and give explicit formulas that increase the precision by ten orders in the inverse distance

Berry phase analogies in nonlinear optics

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Coupling between Inclusions and Membranes at the Nanoscale

International audienceThe activity of cell membrane inclusions (such as ion channels) is influenced by the host lipid membrane, to which they are elastically coupled. This coupling concerns the hydrophobic thickness of the bilayer (imposed by the length of the channel, as per the hydrophobic matching principle) but also its slope at the boundary of the inclusion. However, this parameter has never been measured so far. We combine small-angle x-ray scattering data and a complete elastic model to measure the slope for the model gramicidin channel and show that it is surprisingly steep, in two membrane systems with very different elastic properties. This conclusion is confirmed and generalized by the comparison with recent results in the simulation literature and with conductivity measurements

Periodic attractors in two-photon processes

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Interaction and structuration of membrane-binding and membrane-excluding colloidal particles in lamellar phases

International audienceWithin the framework of a discrete Gaussian model, we present analytical results for the interaction induced by a lamellar phase between small embedded colloids. We consider the two limits of particles strongly adherent to the adjacent membranes and of particles impenetrable to the membranes. Our approach takes into account the finite size of the colloids, the discrete nature of the layers, and includes the Casimir-like effect of fluctuations, which is very important for dilute phases. Monte Carlo simulations of the statistical behavior of the membrane-interacting colloids account semi-quantitatively, without any adjustable parameters, for the experimental data measured on silica nanospheres inserted within lyotropic smectics. We predict the existence of finite-size and densely packed particle aggregates originating from the competition between attractive interactions between colloids in the same layer and repulsion between colloids one layer apart

Form Birefringence In Helical Liquid-crystals

The optical properties of cholesteric and chiral smectic liquid crystals are studied, in the limit of pitch smaller than the wavelength of visible light, by means of a formalism borrowing techniques developed to explain form birefringence effects in particulate media. The behaviour of actual stratified anisotropic substances is shown to be accurately approximated, in this limit, by an effective homogeneous uniaxial crystal, whose dielectric tensor elements are easily obtained from the exact values corresponding to the stratified medium. In two notable cases, i.e., for normal incidence of light and in smectic-C liquid crystals with a critical value of the tilt angle, the optical properties of the stratified material may only be accounted for by introducing an effective medium suitably characterized by optical activity. In all the examined cases, the periodic media appear to be completely equivalent to homogeneous crystals displaying optical activity, up to pitch values corresponding to one half of the first Bragg diffraction band. The model's results having higher relevance both in fundamental studies and applications are described and discussed

Stationary Optical Noise in Planar Nematic Liquid Crystals Near the Fréedericksz Transition

We measure, under stationary conditions, the power spectrum of the transmitted and scattered light intensity in a planar nematic liquid crystal cell as a function of the applied voltage in the neighbourhood of the electrically-induced splay Freedericksz transition. The Freedericksz threshold is independently determined using a standard interferometric technique. The low-frequency noise spectral density of the transmitted light displays a well defined peak at the critical voltage; this feature is instead hidden in the scattering noise. We critically examine the performances of these different experimental techniques and show that noise measurements are an adequate tool to study orientation transitions in nematic liquid crystals