The U.N. Convention on Electronic Contracting: Back From the Dead?

Article published in the Michigan State International Law Review

Mean Curvature Flow with a Neumann Boundary Condition in Flat Spaces

In this thesis I study mean curvature flow in both Euclidean and Minkowski space with a Neumann boundary condition. In Minkowski space I show that for a convex timelike cone boundary condition, with compatible spacelike initial data, mean curvature flow with a perpendicular Neumann boundary condition exists for all time. Furthermore, by a blowdown argument I show convergence as t →∞ to a homothetically expanding hyperbolic hyperplane. I also study the case of graphs over convex domains in Minkowski space. I obtain long time existence for spacelike initial graphs which are taken by mean curvature flow with a Neumann boundary condition to a constant function as t →∞. In Euclidean space I consider boundary manifolds that are rotational tori where I write t for the unit vector field in the direction of the rotation. If the initial manifold M₀ is compatible with the boundary condition, and at no point has t as a tangent vector, then mean curvature flow with a perpendicular Neumann boundary condition exists for all time and converges to a flat cross-section of the boundary torus. I also discuss other constant angle boundary conditions

A Scalable Two-Level Domain Decomposition Eigensolver for Periodic Schr\"odinger Eigenstates in Anisotropically Expanding Domains

Accelerating iterative eigenvalue algorithms is often achieved by employing a spectral shifting strategy. Unfortunately, improved shifting typically leads to a smaller eigenvalue for the resulting shifted operator, which in turn results in a high condition number of the underlying solution matrix, posing a major challenge for iterative linear solvers. This paper introduces a two-level domain decomposition preconditioner that addresses this issue for the linear Schr\"odinger eigenvalue problem, even in the presence of a vanishing eigenvalue gap in non-uniform, expanding domains. Since the quasi-optimal shift, which is already available as the solution to a spectral cell problem, is required for the eigenvalue solver, it is logical to also use its associated eigenfunction as a generator to construct a coarse space. We analyze the resulting two-level additive Schwarz preconditioner and obtain a condition number bound that is independent of the domain's anisotropy, despite the need for only one basis function per subdomain for the coarse solver. Several numerical examples are presented to illustrate its flexibility and efficiency.Comment: 30 pages, 7 figures, 2 table

A new species of Daldinia (Xylariaceae) from the Argentine subtropical montane forest

Based on a combination of morphological, molecular phylogenetic and chemotaxonomic evidence, a new species of Daldinia from Northwest of Argentina is described. Daldinia korfii is morphologically related to D. placentiformis, but differs in having brown vinaceous, KOH-extractable pigments and the tissue below the perithecial layer is composed of inconspicuous to conspicuous alternating zones in the new taxon.Fil: Sir, Esteban Benjamin. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Micologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lambert, C.. Helmholtz-Zentrum für Infektionsforschung; AlemaniaFil: Wendt, L.. Helmholtz-Zentrum für Infektionsforschung; AlemaniaFil: Hladki, Adriana Ines. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Micologia; ArgentinaFil: Romero, Andrea Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Stadler, M.. Helmholtz-Zentrum für Infektionsforschung; Alemani

Student compliance with taught indications for intravenous cannulation during clinical learning

Abstract: One of the guiding principles behind the teaching and performance of a medical intervention is to “firstly do no harm”. Gaining access to a patient’s circulatory system for the purposes of administering fluid and / or medications is commonly achieved through a procedure that involves piercing the skin with a needle and inserting a cannula into a vein. Whilst intravenous (IV) cannulation remains a relatively common procedure, routinely performed by a number of health care professionals, it has the potential to create unintended adverse effects. Subjecting patients to medical procedures in the absence of a clearly established need may be considered an unethical form of “overtreatment”. Conversely, failing to perform an intervention when it is clearly indicated is equally undesirable. For this reason, it is important that medical professionals and educators ensure a real need or indication for IV cannulation exists prior to the performance of the procedure by students. The University of Johannesburg (UJ) is one of four higher education institutions in South Africa that currently offer a four-year professional bachelor degree in emergency medical care. Intravenous cannulation is a clinical procedure that is taught in the second year of study. The didactic approach followed at the UJ is to firstly teach and assess theoretical knowledge and understanding relating to the procedure with regard to the technique, indications, risks and benefits. The procedure is then demonstrated, practiced and assessed in a simulated environment making use of an intravenous trainer (medium fidelity manikin). Thereafter students are required to demonstrate performance of the procedure a set number of times on real patients. Whilst this naturally creates a desire in students to perform IV cannulation when the opportunity presents itself, as mentioned above, seeking clear indications for the performance of the procedure is essential to prevent unnecessary exposure of patients to potential adverse effects. The Department of Emergency Medical Care at the UJ currently teaches four indications for intravenous cannulation in the pre-hospital setting which are well supported by literature. These include: a) the administration of intravenous fluid in an effort to reverse hypovolaemic and associated dehydrated states, b) administration of intravenous medications, c) securing intravenous access in the case of acutely-ill, high-acuity “priority 1” or “code red” patients and d) obtaining blood samples/specimens for further laboratory testing. The authors aimed to assess the extent to which emergency medical care students may have been establishing IV access on patients during the course of their clinical learning without a clear indication

Scaling properties of work fluctuations after quenches at quantum transitions

We study the scaling properties of the statistics of the work done on a generic many-body system at a quantum phase transition of any order and type, arising from quenches of a driving control parameter. For this purpose we exploit a dynamic finite-size scaling framework. Namely, we put forward the existence of a nontrivial finite-size scaling limit for the work distribution, defined as the large-size limit when appropriate scaling variables are kept fixed. The corresponding scaling behaviors are thoroughly verified by means of analytical and numerical calculations in two paradigmatic many-body systems as the quantum Ising model and the Bose-Hubbard model.Comment: 30 pages, 6 figures. Revised versio

Emergency care practitioners’ views on the use of ultrasound in pre-hospital acute care settings

Background: Ultrasound may assist in the detection of life-threatening conditions and evolving pathologies. South African emergency care practitioners (ECPs) working in pre-hospital contexts have historically not used ultrasound to diagnose and treat patients. However, recently published clinical practice guidelines from the Health Professions Council of South Africa (HPCSA) suggest that ultrasound be considered as an adjunct in the provision of pre-hospital emergency care. Our study investigated ECPs’ views and perceptions of introducing ultrasound to their scope of practice. Method: A qualitative prospective approach was followed, using semi-structured interviews with a purposefully selected sample of practising ECPs to investigate and describe their views and perceptions of the use of ultrasound in local pre-hospital emergency care contexts. The interviews were audio recorded and transcribed. Transcripts were critically read before being manually coded to identify core themes and categories. Results: ECPs recognise the potential value of ultrasound for a subset of patients within specific pre-hospital contexts. Concerns around the introduction of ultrasound as a diagnostic adjunct included the potential to create delays in treatment and transportation. Implementation challenges included cost implications and the need for additional education and training. Conclusion: ECPs practising in South African pre-hospital acute care contexts support the use of ultrasound, provided they are adequately trained, and its use does not lead to delays in treatment and arrival at receiving facilities. Additional training on the use of ultrasound may be necessary for ECPs. Further research is required to explore the benefits of ultrasound concerning patient-specific outcomes and the associated costs in resource-constrained pre-hospital emergency care settings

TriadNet: Sampling-free predictive intervals for lesional volume in 3D brain MR images

The volume of a brain lesion (e.g. infarct or tumor) is a powerful indicator of patient prognosis and can be used to guide the therapeutic strategy. Lesional volume estimation is usually performed by segmentation with deep convolutional neural networks (CNN), currently the state-of-the-art approach. However, to date, few work has been done to equip volume segmentation tools with adequate quantitative predictive intervals, which can hinder their usefulness and acceptation in clinical practice. In this work, we propose TriadNet, a segmentation approach relying on a multi-head CNN architecture, which provides both the lesion volumes and the associated predictive intervals simultaneously, in less than a second. We demonstrate its superiority over other solutions on BraTS 2021, a large-scale MRI glioblastoma image database.Comment: Accepted for presentation at the Workshop on Uncertainty for Safe Utilization of Machine Learning in Medical Imaging (UNSURE) at MICCAI 202

Multi-layer Aggregation as a key to feature-based OOD detection

Deep Learning models are easily disturbed by variations in the input images that were not observed during the training stage, resulting in unpredictable predictions. Detecting such Out-of-Distribution (OOD) images is particularly crucial in the context of medical image analysis, where the range of possible abnormalities is extremely wide. Recently, a new category of methods has emerged, based on the analysis of the intermediate features of a trained model. These methods can be divided into 2 groups: single-layer methods that consider the feature map obtained at a fixed, carefully chosen layer, and multi-layer methods that consider the ensemble of the feature maps generated by the model. While promising, a proper comparison of these algorithms is still lacking. In this work, we compared various feature-based OOD detection methods on a large spectra of OOD (20 types), representing approximately 7800 3D MRIs. Our experiments shed the light on two phenomenons. First, multi-layer methods consistently outperform single-layer approaches, which tend to have inconsistent behaviour depending on the type of anomaly. Second, the OOD detection performance highly depends on the architecture of the underlying neural network.Comment: Accepted for presentation at the Workshop on Uncertainty for Safe Utilization of Machine Learning in Medical Imaging (UNSURE) at MICCAI 202