FIRST RESULTS OF SPACE CHARGE SIMULATIONS FOR THE NOVEL MULTI-TURN INJECTION

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Strokes such as acute ischemic stroke require vascular access for endovascular thrombectomy. To navigate the small and complex cerebral vessels with multiple branches, clinicians use guidewires or catheters with pre‐shaped tips. However, complex procedures still face the problem of increased X‐ray exposure for both clinicians and patients. Engineering technologies such as robotic guidewires and catheters are being applied to neurovascular procedures to make them faster and more effective. The technology pre

The quantum magnet Cu₂OSO₄ exhibits a complex magnetic excitation spectrum whose microscopic origin remains an open challenge in condensed matter physics. In this work, we investigate its magnon dynamics by combining inelastic neutron scattering measurements performed on the CAMEA spectrometer at the Paul Scherrer Institut (PSI) with complementary data collected on the TAIPAN triple-axis spectrometer. Linear spin wave theory (LSWT), implemented using the SpinW framework, is employed to refine a microscopic

Disorder in magnetic systems typically suppresses long-range order, promoting short-range states such as spin glasses and magnetic clusters. This is particularly prominent in high-entropy materials, characterized by the random distributions of local magnetic entities and exchange interactions. However, in rare exceptions, long-range magnetic order can persist in high-entropy systems, while the microscopic characters and underlying mechanisms remain elusive, especially the magnetic behaviors of individual el

Multipactor discharge is a vacuum surface discharge on dielectrics or metals triggered by a secondary electron emission avalanche (SEEA), posing a threat to the stable operation of electrical and quantum information devices. This paper performs a first-principle model of multipactor discharge developing on a dielectric with realistic microscopic surface morphology, revealing the critical role of microstructures and roughness in multipactor physics, which is often neglected in existing studies. The simulatio

Introducing symmetry breaking in materials enables the emergence of functionalities. This can be microscopically and macroscopically driven by applying external stimuli such as mechanical stress, electric field, temperature, and chemical modification. For instance, non‐zero net dipole moments are formed in a material with the presence of local charged defects or their clusters, which can alter the crystal structure, charge states, and electrostatic potential across the material. Here, a conceptual approach

The power exhaust through the scrape-off layer (SOL) in fusion reactors is expected to be significantly higher than in ITER, thus questioning the extrapolation of the ITER exhaust solution to these devices. The snowflake (SF) magnetic configuration is one of the alternative exhaust configurations being considered to mitigate the heat vessel loads in fusion reactors. The SF configuration features a second-order null of the poloidal magnetic field, i.e. a point where the poloidal magnetic field and its spatia

This paper aims at an accurate and ecient computation of eective quantities, e.g., the homogenized coecients for approximating the solu- tions to partial dierential equations with oscillatory coecients. Typical multiscale methods are based on a micro-macro coupling, where the macro model describes the coarse scale behaviour, and the micro model is solved only locally to upscale the eective quantities, which are missing in the macro model. The fact that the micro problems are solved over small domains within

X-ray diffraction measurements show that the high-temperature superconductor YBa2Cu3O6.54, with ortho-II oxygen order, has charge-density-wave order in the absence of an applied magnetic field. The dominant wave vector of the charge density wave is q(CDW) = (0, 0.328(2), 0.5), with the in-plane component parallel to the b axis (chain direction). It has a similar incommensurability to that observed in ortho-VIII and ortho-III samples, which have different dopings and oxygen orderings. Our results for ortho-I

This project presents the theoretical background in electrophysiology that is used as a basis in the development of numerical methods for the simulation of heart’s electrical activity. We discuss the mathematical models currently used in cardiac electrophysiology research to simulate the propagation of an action potential wave, and then focus on the description of the ionic currents. This study allows us to anticipate the numerical model sensitivity with regard to the discretization, with the aim of recover

Diffusion magnetic resonance imaging (dMRI) is a non-invasive method that allows connectivity mapping of the brain. However, despite major advances in this field, accurate inference of these patterns and its applicability within a clinical context is still in its early stages. This thesis describes a conceptually novel method for reconstructing neuronal pathways inside the brain from diffusion-weighted imaging (DWI) measurements with high angular resolution and short data acquisition time. The proposed meth

We consider a 3-dimensional Dirac operator H_0 with non-constant magnetic field of constant direction, perturbed by a sign-definite matrix-valued potential V decaying fast enough at infinity. Then we determine asymptotics, as the energy goes to +m and -m, of the spectral shift function for the pair (H_0,H_0+V). We obtain, as a by-product, a generalised version of Levinson's Theorem relating the eigenvalues asymptotics of H_0+V near +m and -m to the scattering phase shift for the pair (H_0,H_0+V).

Cardiovascular diseases have a major impact in Western countries. Mathematical models and numerical simulations can help the understanding of physiological and pathological processes, complementing the information provided to medical doctors by medical imaging and other non-invasive means, and opening the possibility of a better diagnosis and more in-depth surgical planning.This book offers a mathematically sound and up-to-date foundation to the training of researchers, and serves as a useful reference for

During this project, ultrasensitive cantilevers designed for nuclear magnetic resonance applications were fabricated and characterised. The cantilevers are 500, 340 or 200 μm long, 10 or 20 μm wide and 500 or 340 nm thick and integrate a thin film of cobalt at the free end. This thin-film can be magnetised. Their fabrication requires novel techniques such as silicon-on-insulator technology, Al protective layer deposition, high anisotropic dry etching or HF-vapour release. A dynamic and a static model of the

At frequencies below the electron cyclotron and above the lower hybrid frequency in a magnetoplasma, the refractive index is anisotropic and shows resonances at certain angles caused by electron inertia. For a radiating antenna in a plasma, the short wavelengths near this resonance angle may contribute to the radiation pattern of the antenna. A series of experiments is reported, in which waves were excited using a small 1-cm-diam electrostatically coupled antenna into a preformed plasma, densities (n(e)) fr

This article discusses neutron scattering measurements on the cuprate, high transition temperature superconductor La2-xSrxCuO4 (LSCO) in an applied magnetic field. LSCO is a type-II superconductor and magnetic flux can penetrate the material via the formation of vorticies. Phase coherent superconductivity characterized by zero resistance is suppressed to the lower field-dependent irreversibility temperature (T-irr(H)) and occurs when the vortices freeze into a lattice. Because superconductivity is destroyed

We have studied the evolution of the magnetic properties of monolayer-high cobalt islands on a Pt(111) surface as function of their exposure to oxygen. We observe a sequential quenching of magnetic anisotropy and magnetic moment. For minute exposures to oxygen this leads to an enhancement of the maximum susceptibility of up to 66% for chi". We show that the reason for the reduction of the anisotropy before the one of the moment is due to preferential oxygen adsorption at the island edges, which are the main

We present an inelastic neutron scattering study of the spin dynamics in the mixed phase of the high-T-c superconductor La2-xSrxCuO4, In the overdoped regime (x = 0. 17, T-c = 37 K) the application of a magnetic field induces a spectral weight redistribution centered around the zero-field spin gap (Delta(SG) approximate to 5 6.5 meV). Moreover the opening of the spin gap seems to track the irreversibility temperature (related to the melting of the vortex lattice) rather than T-c, indicating an unusual inter

The crystallographic structure of the cuprate Sr14Cu24O41 is a misfit stacking of layers of two distinct quantum-spin systems: linear edge-sharing CuO2 chains and 2-leg Cu2O3 spin-ladders. Interestingly, the CuO2-chains contain a large amount of holes which give rise to a quasi-2D charge order at low temperature, associated with a strong lattice distortion. In order to understand better the nature of excitation spectra in both sub-systems (in particular their possible hybrid or orbital nature), we have rece

We have carried out an ab initio molecular dynamics simulation of liquid oxygen, a molecular fluid in which the individual 02 units carry a molecular magnetic moment. In addition to the atomic and electronic structures, our simulation describes the evolution of the noncollinear magnetic structure. The atomic structure shows a strong preference for parallel alignment of first-neighbour molecules. The magnetic structure shows strong short-range antiferromagnetic correlations, in agreement with spin-polarized

This paper describes quantitatively the magnetic field inside the windings of a HTS transformer. The results are obtained by means of finite element method simulations, using the electromagnetic software package Flux2D. The transformer design has been made by ŠKODA in the European project BIG-POWA. The ratings of the transformer are U1 = 400 V, I1 = 47 A, U2 = 133 V, I2 = 140 A (rms values). The magnetic field in the superconducting windings has been calculated in the steady state regime at 50 Hz. It is non

FIRST RESULTS OF SPACE CHARGE SIMULATIONS FOR THE NOVEL MULTI-TURN INJECTION

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Magnetic Control of Intravascular Collaborative Robotic (Cobot) Guidewire: Neurovascular Intervention Studies in Phantom and Swine Models

Study of the Magnetic Properties of Cu2OSO4. High-Resolution Neutron Spectroscopy

Long-range magnetic order with disordered spin orientations in a high-entropy antiferromagnet

First-principle model of multipactor discharge considering realistic surface morphology: the role of microstructures

Tunable and Persistent Macroscopic Polarization in Nominally Centrosymmetric Defective Oxides

Turbulence and flows in the plasma boundary of snowflake magnetic configurations

MATHICSE technical Report : A parabolic local problem with exponential decay of the resonance error for numerical homogenization

X-Ray Diffraction Observations of a Charge-Density-Wave Order in Superconducting Ortho-II YBa_{2}Cu_{3}O_{6.54} Single Crystals in Zero Magnetic Field

Phenomenological and physiological approaches in the study of cardiac alternans: Theoretical background, mathematical modeling and numerical simulations

Efficient Sampling for Accelerated Diffusion Magnetic Resonance Imaging

Asymptotics near ±m of the spectral shift function for Dirac operators with non-constant magnetic fields

Cardiovascular Mathematics

Fabrication and characterisation of ultrasensitive monocrystalline silicon cantilevers with integrated magnetic tips

Transitions from electrostatic to electromagnetic whistler wave excitation

Effects of magnetic field on the cuprate high-T-c superconductor La2-xSrxCuO4

Oxidation induced enhanced magnetic susceptibility of Co islands on Pt(111)

Spin dynamics in the mixed phase of La2-xSrxCuO4 (x=0.10, x=0.17)

Longitudinal-neutron-polarization-analysis study of the spin dynamics in Sr14Cu24O41

Structural and magnetic correlations in liquid oxygen: an ab initio molecular dynamics study

Modelling the magnetic field effects in a high-Tc superconducting transformer