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Imaging Mie polarimetry is key to determining spatially resolved information about the properties, i.e. refractive index and grain size, of particle clouds, such as during the growth process in reactive particle producing plasmas. Asymmetries in the intensity maps of the different Stokes parameters resulting from the anisotropic scattering of polarized laser light complicate the analysis and require the use of radiative transfer (RT) simulations. We use RT simulations to investigate the asymmetric scattering behavior based on a model of a typical reactive argon-acetylene plasma. We address possible misinterpretations and explore the potential for analyzing particle properties. We find that the asymmetric pattern of the intensity distributions is highly dependent on the refractive index, providing the potential to determine the refractive index and grain size at any time during the growth process.

When considering particles produced in reactive plasmas, their basic properties, such as refractive index and grain size often need to be known. They can be constrained both ex-situ, e.g., by microscopy, and in-situ by polarimetry, i.e., analyzing the polarization state of scattered light. Polarimetry has the advantage of temporal resolution and real-time measurement, but the analysis is often limited by the assumption of single scattering and thus optically thin dust clouds. This limits the investigation of the growth process typically to grain sizes smaller than about 200 nm. Using 3D polarized radiative transfer simulations, however, it is possible to consider multiple scattering and to analyze the properties of dense particle clouds. We study the impact of various properties of dust clouds on the scattering polarization, namely the optical depth of the cloud, the spatial density distribution of the particles, their refractive index as well as the particle size dispersion. We find that ambiguities can occur regarding optical depth and spatial density distribution as well as regarding refractive index and particle size dispersion. Determining the refractive index correctly is especially important as it has a strong impact on the derived particle sizes. With this knowledge, we are able to design an in-situ diagnostics strategy for the investigation of the particle growth process based on radiative transfer simulations which are used to model the polarization over the whole growth process. The application of this strategy allows us for the first time to analyze the polarization measured during a growth experiment in a reactive argon-acetylene plasma for particle radii up to 280 nm.

In order to study the initial conditions of planet formation, it is crucial to obtain spatially resolved multi-wavelength observations of the innermost region of protoplanetary discs. We evaluate the advantage of combining observations with MATISSE/VLTI and ALMA to constrain the radial and vertical structure of the dust in the innermost region of circumstellar discs in nearby star-forming regions. Based on a disc model with a parameterized dust density distribution, we apply 3D radiative-transfer simulations to obtain ideal intensity maps. These are used to derive the corresponding wavelength-dependent visibilities we would obtain with MATISSE as well as ALMA maps simulated with CASA. Within the considered parameter space, we find that constraining the dust density structure in the innermost \\(5\\,\\)au around the central star is challenging with MATISSE alone, whereas ALMA observations with reasonable integration times allow us to derive significant constraints on the disc surface density. However, we find that the estimation of the different disc parameters can be considerably improved by combining MATISSE and ALMA observations. For example, combining a 30-minute ALMA observation (at 310 GHz with an angular resolution of 0.03\\(^{\\prime\\prime}\\)) for MATISSE observations in the L and M bands (with visibility accuracies of about \\(3\\,\\%\\)) allows the radial density slope and the dust surface density profile to be constrained to within \\(\\Delta \\alpha=0.3\\) and \\(\\Delta (\\alpha-\\beta)=0.15\\), respectively. For an accuracy of \\({\\sim 1\\%}\\) even the disc flaring can be constrained to within \\(\\Delta \\beta=0.1\\). To constrain the scale height to within \\(5\\,\\)au, M band accuracies of \\(0.8\\,\\%\\) are required. While ALMA is sensitive to the number of large dust grains settled to the disc midplane we find that the impact of the surface density distribution of the large grains on the observed quantities is small.

Interferometric observations of protoplanetary disks by VLTI and ALMA have greatly improved our understanding of the detailed structure of these planetary birthplaces. These observations have revealed a variety of large-scale disk substructures, including rings, gaps, and spirals, spanning tens to hundreds of au, supporting the predictions of planet formation models. Recent instruments, such as MATISSE at the VLTI, allow one to resolve and investigate the inner few au of protoplanetary disks in nearby star formation regions, shedding light on the traces of planet formation and evolution at these small scales. The aim of this work is to assess the feasibility of interferometric observations of small-scale planet-induced substructures in protoplanetary disks in nearby star-forming regions. We aim to characterize these substructures in multi-wavelength and multi-epoch observations and subsequently differentiate between simulation parameters. On the basis of 3D hydrodynamic simulations of embedded planetary companions and subsequent 3D Monte Carlo radiative transfer simulations, we calculated and analyzed interferometric observables, assuming observations with the VLTI in the K, L, M, and N bands. The hydrodynamic simulations exhibit mass-dependent planet-induced density waves that create observable substructures, most notably for the considered case of a 300 \\(M_\\) planet. These substructures share similarities with observed large-scale structures and feature a prominent accretion region around the embedded planet. The visibilities show a detectable variability for multi-epoch VLTI/GRAVITY and VLTI/MATISSE observations, caused by the orbital motion of the planet, that are distinguishable from other sources of variability due to their unique combination of timescale and amplitude.

Introduction To ensure that pre-final year medical students at Stellenbosch University were able to resume clinical training during the COVID-19 pandemic, a 12-week integrated rotation was introduced, during which students were distributed across a widespread training platform in two provinces of South Africa, utilizing a range of health care facilities in both rural and urban areas, rather than the central academic hospital (CAH) in which they would have been doing clerkships. Called the Integrated Distributed Engagement to Advance Learning (IDEAL) rotation, this clerkship was based on supervised engagement in healthcare services, focusing on patient-based clinical training, self-regulated learning and student participation as integral members of clinical teams. The success of this emergency intervention has led to its formal incorporation into the medical curriculum. This study aimed to understand the factors that influenced learning among students undertaking the IDEAL rotation at multiple sites on a distributed training platform. Methods Using an interpretive paradigm, we sought to conduct focus group interviews with students who completed the first iteration of the IDEAL rotation in the year after they had undertaken it to understand their experiences. All 252 students who were eligible were invited to participate by email on several occasions. Ultimately three focus group discussions and two individual interviews were undertaken, based on volunteers. Using a semi-structured interview guide, these explored student perceptions of their learning and growth through the rotation. Inductive and deductive analysis was carried out to identify themes. Findings Student descriptions of their learning experiences coalesced in 6 themes. The rotation was an enabling learning experience , which was more practically focused and assisted students in developing confidence in their clinical skills. It was seen to be a humanizing learning experience with greater opportunities for the development of relationships with patients and families, as well as with health professionals, who made them feel part of the team, so it was also a more collegial learning experience . At the same time, it was a variable learning experience with a lack of standardization on a number of levels and challenges being experienced at particular sites regarding both logistics and the nature of the exposure. Students perceived it to be a very different learning experience from what they had encountered in the CAH in terms of relationships, the kinds of patients and problems they saw, and their active participation. Through this, they also learned more about themselves and their roles, making it a personal learning journey . The findings confirm the importance of the dimensions of person, participation and place for being and becoming a doctor in a clinical environment. Conclusions Student learning experiences in the IDEAL rotation emphasize the importance of context, reinforcing the value of a distributed training platform in developing health professionals who are responsive to their environment. They emphasize the vital role of active participation in learning and the centrality of relationships in medical training, helping to develop graduates who are human beings and not only human doings.

Background Despite benefits of endovascular treatment (EVT) for large vessel occlusion (LVO) ischemic stroke, space-occupying brain edema (BE) represents a detrimental complication. In critical-care settings, CT-imaging is needed for monitoring these patients. Yet, bed-side techniques with the potential to predict whether patients develop BE or not would facilitate a time- and cost-efficient patient care. We assessed clinical significance of automated pupillometry in the follow-up of patients undergoing EVT. Methods From 10/2018 to 10/2021, neurocritical-care-unit patients were retrospectively enrolled after EVT of anterior circulation LVO. We monitored parameters of pupillary reactivity [light-reflex-latency (Lat), constriction- and redilation-velocities (CV, DV), percentage-change-of-apertures (per-change); NeurOptics-pupilometer ® ] up to every hour on day 1–3 of ICU stay. BE was defined as midline shift ≥ 5 mm on follow-up imaging 3–5 days after EVT. We calculated mean values of intra-individual differences between successive pairs of parameters (mean-deltas), determined best discriminative cut-off values for BE development (ROC-analyses), and evaluated prognostic performance of pupillometry for BE development (sensitivity/specificity/positive-/negative-predictive-values). Results 3241 pupillary assessments of 122 patients [67 women, 73 years (61.0–85.0)] were included. 13/122 patients developed BE. Patients with BE had significantly lower CVs, DVs, and smaller per-changes than patients without BE. On day 1 after EVT mean-deltas of CV, DV, and per-changes were significantly lower in patients with than without BE. Positive-predictive-values of calculated thresholds to discriminate both groups were considerably low, yet, we found high negative-predictive-values for CV, DV, per-changes, and mean-deltas (max.: 98.4%). Conclusion Our data suggest associations between noninvasively detected changes in pupillary reactivity and BE early after LVO-EVT. Pupillometry may identify patients who are unlikely to develop BE and may not need repetitive follow-up-imaging or rescue-therapy.

Bone fragility due to osteopenia, osteoporosis or debilitating focal skeletal dysplasias is a frequent observation in the Mendelian disease Neurofibromatosis type 1 (NF1). To determine the mechanisms underlying bone fragility in NF1 we analyzed two conditional mouse models, Nf1Prx1 (limb knock-out) and Nf1Col1 (osteoblast specific knock-out), as well as cortical bone samples from individuals with NF1. We examined mouse bone tissue with micro-computed tomography, qualitative and quantitative histology, mechanical tensile analysis, small-angle X-ray scattering (SAXS), energy dispersive X-ray spectroscopy (EDX), and scanning acoustic microscopy (SAM). In cortical bone of Nf1Prx1 mice we detected ectopic blood vessels that were associated with diaphyseal mineralization defects. Defective mineral binding in the proximity of blood vessels was most likely due to impaired bone collagen formation, as these areas were completely devoid of acidic matrix proteins and contained thin collagen fibers. Additionally, we found significantly reduced mechanical strength of the bone material, which was partially caused by increased osteocyte volume. Consistent with these observations, bone samples from individuals with NF1 and tibial dysplasia showed increased osteocyte lacuna volume. Reduced mechanical properties were associated with diminished matrix stiffness, as determined by SAM. In line with these observations, bone tissue from individuals with NF1 and tibial dysplasia showed heterogeneous mineralization and reduced collagen fiber thickness and packaging. Collectively, the data indicate that bone fragility in NF1 tibial dysplasia is partly due to an increased osteocyte-related micro-porosity, hypomineralization, a generalized defect of organic matrix formation, exacerbated in the regions of tensional and bending force integration, and finally persistence of ectopic blood vessels associated with localized macro-porotic bone lesions.

Introduction : Coronary artery disease in diabetic patients is connected with worse prognosis in comparison with patients who have coronary artery disease but no diabetes. Identification of coronary artery disease risk factors and treatment in accordance with the guidelines of Polish Cardiological and Diabetic Associations may contribute to the improved prognosis in this group of patients. Aim : To evaluate the incidence of coronary artery disease risk factors and to obey the rules of secondary prevention in diabetic patients who are referred to coronary angiography due to ischaemic heart disease. The aim was also to estimate the knowledge of those patients whether they are familiar with risk factors of coronary artery disease or not. Material and methods : In the trial were involved 121 patients including 41 (33.88%) women and 80 (66.12%) men with type 2 diabetes and stable coronary artery disease referred to coronary angiography procedure. All of these patients had previously been treated due to ischaemic heart disease . The data was received based on the interview with the patients as well as the analysis of laboratory tests at admission and the measurement of arterial blood pressure. All patients completed the survey of coronary artery disease risk factors. Results : Based on the interview hypertension was found in 95.87% of the patients with diabetes and coronary artery disease. Obesity (BMI > 30 kg/m2) was found in half of these patients. Total cholesterol concentration values recommended by PTK and PTD reached 65.29%, cholesterol LDL < 100 mg/dl - 64.46%, LDL < 70 mg/dl - ok. 30%. In a high percentage of women (65.85%), HDL cholesterol < 50 mg/dl while in men the value of HDL cholesterol (< 40 mg/dl) was found in 57.50% of patients. Every tenth patient smoked tobacco. Half of the patients evaluated their knowledge of risk factors as well as complications in coronary artery disease as rather little. Only every fifth patient believes that diabetes has influence on the development of coronary artery diseases. Conclusions : There should be more pressure on educating patients with diabetes as for prevention of coronary artery disease risk factors and treatment possibilities.