Anomalous direction for skyrmion bubble motion

Magnetic skyrmions are localized topological excitations that behave as particles and can be mobile, with great potential for novel data storage devices. In this work, the current-induced dynamics of large skyrmion bubbles is studied. When skyrmion motion in the direction opposite to the electron flow is observed, this is usually interpreted as a perpendicular spin current generated by the spin Hall effect exerting a torque on the chiral N\'{e}el skyrmion. By designing samples in which the direction of the net generated spin current can be carefully controlled, we surprisingly show that skyrmion motion is always against the electron flow, irrespective of the net vertical spin-current direction. We find that a negative bulk spin-transfer torque is the most plausible explanation for the observed results, which is qualitatively justified by a simple model that captures the essential behaviour. These findings demonstrate that claims about the skyrmion chirality based on their current-induced motion should be taken with great caution

Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers

A nonlinear magnetoresistance - called unidirectional spin-Hall magnetoresistance - is recently experimentally discovered in metallic bilayers consisting of a heavy metal and a ferromagnetic metal. To study the fundamental mechanism of the USMR, both ferromagnetic and heavy metallic layer thickness dependence of the USMR are presented in a Pt/Co/AlOx trilayer at room temperature. To avoid ambiguities, second harmonic Hall measurements are used for separating spin-Hall and thermal contributions to the non-linear magnetoresistance. The experimental results are fitted by using a drift-diffusion theory, with parameters extracted from an analysis of longitudinal resistivity of the Co layer within the framework of the Fuchs-Sondheimer model. A good agreement with the theory is found, demonstrating that the USMR is governed by both the spin-Hall effect in the heavy metallic layer and the metallic diffusion process in the ferromagnetic layer

Magnetostatics of Room Temperature Compensated Co/Gd/Co/Gd-based Synthetic Ferrimagnets

Flexibility for interface engineering, and access to all-optical switching of the magnetization, make synthetic ferrimagnets an interesting candidate for advanced opto-spintronic devices. Moreover, due to their layered structure and disordered interfaces they also bear promise for the emerging field of graded magnetic materials. The fastest and most efficient spin-orbit torque driven manipulation of the magnetic order in this material system generally takes place at compensation. Here, we present a systematic experimental and modeling study of the conditions for magnetization compensation and perpendicular magnetic anisotropy in the synthetic ferrimagnetic Co/Gd/Co/Gd system. A model based on partial intermixing at the Co/Gd interfaces of this system has been developed which explains the experiments well, and provides a new tool to understand its magnetic characteristics. More specifically, this work provides new insight in the decay of the Co proximity-induced magnetization in the Gd, and the role the capping layer plays in the Gd magnetization

Study protocol of validating a numerical model to assess the blood flow in the circle of Willis

Introduction We developed a zero-dimensional (0D) model to assess the patient-specific haemodynamics in the circle of Willis (CoW). Similar numerical models for simulating the cerebral blood flow (CBF) had only been validated qualitatively in healthy volunteers by magnetic resonance (MR) angiography and transcranial Doppler (TCD). This study aims to validate whether a numerical model can simulate patient-specific blood flow in the CoW under pathological conditions. Methods and analysis This study is a diagnostic accuracy study. We aim to collect data from a previously performed prospective study that involved patients with aneurysmal subarachnoid haemorrhage (aSAH) receiving both TCD and brain Computerd Tomography angiography (CTA) at the same day. The cerebral flow velocities are calculated by the 0D model, based on the vessel diameters measured on the CTA of each patient. In this study, TCD is considered the gold standard for measuring flow velocity in the CoW. The agreement will be analysed using Pearson correlation coefficients. Ethics and dissemination This study protocol has been approved by the Medical Ethics Review Board of the University Medical Center Groningen: METc2019/103. The results will be submitted to an international scientific journal for peer-reviewed publication. Trial registration number NL8114

Patient-Specific Cerebral Blood Flow Simulation Based on Commonly Available Clinical Datasets

Cerebral hemodynamics play an important role in the development of cerebrovascular diseases. In this work, we propose a numerical framework for modeling patient-specific cerebral blood flow, using commonly available clinical datasets. Our hemodynamic model was developed using Simscape Fluids library in Simulink, based on a block diagram language. Medical imaging data obtained from computerized tomography angiography (CTA) in 59 patients with aneurysmal subarachnoid hemorrhage was used to extract arterial geometry parameters. Flow information obtained from transcranial Doppler (TCD) measurement was employed to calibrate input parameters of the hemodynamic model. The results show that the proposed numerical model can reproduce blood flow in the circle of Willis (CoW) per patient per measurement set. The resistance at the distal end of each terminal branch was the predominant parameter for the flow distribution in the CoW. The proposed model may be a promising tool for assessing cerebral hemodynamics in patients with cerebrovascular disease

Influence of social support on return to work after total hip or total knee arthroplasty:a prospective multicentre cohort study

OBJECTIVES: There is strong evidence that social support is an important determinant of return to work (RTW). Little is known about the role of social support in RTW after total hip or knee arthroplasty (THA/TKA). Objective was to examine the influence of preoperative and postoperative perceived social support on RTW status 6 months postoperatively. DESIGN: A prospective multicentre cohort study was conducted. SETTING: Orthopaedic departments of four Dutch medical centres; a tertiary university hospital, two large teaching hospitals and a general hospital. PARTICIPANTS: Patients planned to undergo THA/TKA, aged 18-63 and employed preoperatively were included. MAIN OUTCOME MEASURES: Questionnaires were filled out preoperatively and 3 and 6 months postoperatively and included questions to assess patients' perceived social support targeting three sources of social support: from home (friends, family), from work (coworkers, supervisors) and from healthcare (occupational physician, general practitioner, other caregivers). Control variables included age, gender, education, type of arthroplasty and comorbidities. RTW was defined as having fully returned to work 6 months postoperatively. Univariate and multivariate logistic regression analyses were conducted. RESULTS: Enrolled were 190 patients (n=77 THA, n=113 TKA, median age was 56 years, 56% women). The majority returned to work (64%). Preoperatively, social support from the occupational physician was associated with RTW (OR 2.53, 95% CI 1.15 to 5.54). Postoperatively, social support from the occupational physician (OR 3.04, 95% CI 1.43 to 6.47) and the supervisor (OR 2.56, 95% CI 1.08 to 6.06) was associated with RTW. CONCLUSIONS: This study underscores the importance of work-related social support originating from the occupational physician and supervisor in facilitating RTW after primary THA/TKA, both preoperatively and postoperatively. Further research is needed to confirm our results and to understand the facilitating role of social support in RTW, as arthroplasty is being performed on a younger population for whom work participation is critical

The Role of Hemodynamics through the Circle of Willis in the Development of Intracranial Aneurysm:A Systematic Review of Numerical Models

Background: The role of regional hemodynamics in the intracranial aneurysmal formation, growth, and rupture has been widely discussed based on numerical models over the past decades. Variation of the circle of Willis (CoW), which results in hemodynamic changes, is associated with the aneurysmal formation and rupture. However, such correlation has not been further clarified yet. The aim of this systematic review is to investigate whether simulated hemodynamic indices of the CoW are relevant to the formation, growth, or rupture of intracranial aneurysm. Methods: We conducted a review of MEDLINE, Web of Science, and EMBASE for studies on the correlation between hemodynamics indices of the CoW derived from numerical models and intracranial aneurysm up to December 2020 in compliance with PRISMA guidelines. Results: Three case reports out of 1046 publications met our inclusion and exclusion criteria, reporting 13 aneurysms in six patients. Eleven aneurysms were unruptured, and the state of the other two aneurysms was unknown. Wall shear stress, oscillatory shear index, von-Mises tension, flow velocity, and flow rate were reported as hemodynamic indices. Due to limited cases and significant heterogeneity between study settings, meta-analysis could not be performed. Conclusion: Numerical models can provide comprehensive information on the cerebral blood flow as well as local flow characteristics in the intracranial aneurysm. Based on only three case reports, no firm conclusion can be drawn regarding the correlation between hemodynamic parameters in the CoW derived from numerical models and aneurysmal formation or rupture. Due to the inherent nature of numerical models, more sensitive analysis and rigorous validations are required to determine its measurement error and thus extend their application into clinical practice for personalized management. Prospero registration number: CRD42021125169

Young men are at higher risk of failure after ACL hamstring reconstructions:a retrospective multivariate analysis

Background: Results of ACL reconstruction are influenced by both patient and surgical variables. Until now a significant amount of studies have focused on the influence of surgical technique on primary outcome, often leaving patient variables untouched. This study investigates the combined influence of patient and surgical variables through multivariate analysis. Methods: Single-center retrospective cohort study. All patients who underwent primary ACL hamstring reconstruction within a 5-year period were included. Patient characteristics (gender, age, height, weight, BMI at time of surgery) and surgical variables (surgical technique, concomitant knee injury, graft diameter, type of femoral and tibial fixation) were collected. Patients were asked about Tegner Activity Scale (TAS), complications and revision surgery. Multivariate logistic regression was used to study risk factors. First graft failure and potential risk factors (patient and surgical) were univariately assessed. Risk factors with a p-value ≤ 0.05 were included in the multivariate model. Results: Six hundred forty-seven primary ACL hamstring reconstructions were included. There were 41 graft failures (failure rate 6.3%). Patient gender, age, height and preoperative TAS had a significant influence on the risk of failure in the univariate analysis. The multivariate analyses showed that age and sex remained significant independent risk factors. Patients with a failed ACL reconstruction were younger (24.3 vs 29.4 years, OR 0.937), with women at a lower risk for failure of their ACL reconstruction (90.2% males vs 9.8% females, female OR 0.123). ACL graft diameter and other surgical variables aren’t confounders for graft failure. Conclusion: This study shows that patient variables seem to have a larger influence on the failure rate of ACL hamstring reconstructive surgery than surgical variables. Identification of the right patient variables can help us make more informed decisions for our patients and create patient-specific treatment protocols. Young men’s higher risk of failure suggests that these patients may benefit from a different reconstruction technique, such as use of a patellar tendon or combined ligament augmentation. Level of evidence: Retrospective cohort III

Mechanistic overlap between chronic lung injury and cancer:ERS Lung Science Conference 2017 report

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Psychosocial Working Conditions Play an Important Role in the Return-to-Work Process After Total Knee and Hip Arthroplasty

Purpose Both personal and work-related factors affect return to work (RTW) after total knee arthroplasty (TKA) and total hip arthroplasty (THA). Little is known about work-related factors associated with the recovery process. This study aimed to determine which work-related factors are associated with time to RTW for both TKA and THA patients. Methods A prospective multicenter survey study was conducted that included patients aged 18-63, had a paid job and were scheduled to undergo primary TKA/THA. Surveys were completed preoperatively, 6 weeks, and 3, 6, and 12 months postoperatively, and included four domains of work-related factors: work characteristics, physical working conditions, psychosocial working conditions and work adjustments. Control variables included age, sex, education, and comorbidity. Time to RTW was defined as days from surgery until RTW. Multivariate linear regression analyses were conducted separately for TKA/THA patients. Results Enrolled were 246 patients (n = 146 TKA, n = 100 THA, median age 56 years, 57% female). Median time to RTW was 79 days (IQR 52.0-146.0). Mainly physical tasks (TKA: B 58.2, 95%CI 9.5-106.8; THA: B 52.1, 95%CI 14.1-90.2) and a combination of physical and mental tasks (TKA: B 50.2, 95%CI 6.4-94.0; THA B 54.0, 95%CI 24.2-83.7) were associated with longer time to RTW after both TKA and THA. More possibilities for personal job development (B - 12.8, 95%CI - 25.3-0.4) and more work recognition (B - 13.2, 95%CI - 25.5 to - 0.9) were significantly associated with shorter time to RTW after TKA. Higher quality of supervisor leadership (B - 14.1, 95%CI - 22.2 to - 6.0) was significantly associated with shorter time to RTW after THA. Conclusion The findings of this study stress the importance of psychosocial working conditions, besides type of job tasks, in RTW after TKA/THA. Further research on work-related factors is needed, as arthroplasty is being performed on an increasingly younger population of knee and hip OA patients for whom participating in work is of critical importance