Matrix similarity transformations derived from extended qq-analogues of the Toda equation and Lotka-Volterra system

The $q$-Toda equation is derived from replacing ordinary derivatives with $q$-derivatives in the famous Toda equation. In this paper, we associate an extension of the $q$-Toda equation with matrix eigenvalue problems, and then show applications of its time-discretization to computing matrix eigenvalues. With respect to the Lotka-Volterra system, we also have the similar discussion on the case of the Toda equation

Eigen electric moments of magnetic-dipolar modes in quasi-2D ferrite disk particles

A property associated with a vortex structure becomes evident from an analysis of confinement phenomena of magnetic oscillations in a quasi-2D ferrite disk with a dominating role of magnetic-dipolar (non-exchange-interaction) spectra. The vortices are guaranteed by the chiral edge states of magnetic-dipolar modes which result in appearance of eigen electric moments oriented normally to the disk plane. Due to the eigen-electric-moment properties, a ferrite disk placed in a microwave cavity is strongly affected by the cavity RF electric field with a clear evidence for multi-resonance oscillations. For different cavity parameters, one may observe the "resonance absorption" and "resonance repulsion" behaviors

Bipolar-Driven Large Magnetoresistance in Silicon

Large linear magnetoresistance (MR) in electron-injected p-type silicon at very low magnetic field is observed experimentally at room temperature. The large linear MR is induced in electron-dominated space-charge transport regime, where the magnetic field modulation of electron-to-hole density ratio controls the MR, as indicated by the magnetic field dependence of Hall coefficient in the silicon device. Contrary to the space-charge-induced MR effect in unipolar silicon device, where the large linear MR is inhomogeneity-induced, our results provide a different insight into the mechanism of large linear MR in non-magnetic semiconductors that is not based on the inhomogeneity model. This approach enables homogeneous semiconductors to exhibit large linear MR at low magnetic fields that until now has only been appearing in semiconductors with strong inhomogeneities.Comment: 23 pages, 4 figures (main text), 6 figures (supplemental material

Evolution and stability of a magnetic vortex in small cylindrical ferromagnetic particle under applied field

The energy of a displaced magnetic vortex in a cylindrical particle made of isotropic ferromagnetic material (magnetic dot) is calculated taking into account the magnetic dipolar and the exchange interactions. Under the simplifying assumption of small dot thickness the closed-form expressions for the dot energy is written in a non-perturbative way as a function of the coordinate of the vortex center. Then, the process of losing the stability of the vortex under the influence of the externally applied magnetic field is considered. The field destabilizing the vortex as well as the field when the vortex energy is equal to the energy of a uniformly magnetized state are calculated and presented as a function of dot geometry. The results (containing no adjustable parameters) are compared to the recent experiment and are in good agreement.Comment: 4 pages, 2 figures, RevTe

Pain in individuals with idiopathic inflammatory myopathies, other systemic autoimmune rheumatic diseases, and without rheumatic diseases: A report from the COVAD study

Myositis; Pain; Rheumatic diseasesMiositis; Dolor; Enfermedades reumáticasMiositis; Dolor; Malalties reumàtiquesObjectives To compare pain intensity among individuals with idiopathic inflammatory myopathies (IIMs), other systemic autoimmune rheumatic diseases (AIRDs), and without rheumatic disease (wAIDs). Methods Data were collected from the COVID-19 Vaccination in Autoimmune Diseases (COVAD) study, an international cross-sectional online survey, from December 2020 to August 2021. Pain experienced in the preceding week was assessed using numeral rating scale (NRS). We performed a negative binomial regression analysis to assess pain in IIMs subtypes and whether demographics, disease activity, general health status, and physical function had an impact on pain scores. Results Of 6988 participants included, 15.1% had IIMs, 27.9% had other AIRDs, and 57.0% were wAIDs. The median pain NRS in patients with IIMs, other AIRDs, and wAIDs were 2.0 (interquartile range [IQR] = 1.0–5.0), 3.0 (IQR = 1.0–6.0), and 1.0 (IQR = 0–2.0), respectively (P < 0.001). Regression analysis adjusted for gender, age, and ethnicity revealed that overlap myositis and antisynthetase syndrome had the highest pain (NRS = 4.0, 95% CI = 3.5–4.5, and NRS = 3.6, 95% CI = 3.1–4.1, respectively). An additional association between pain and poor functional status was observed in all groups. Female gender was associated with higher pain scores in almost all scenarios. Increasing age was associated with higher pain NRS scores in some scenarios of disease activity, and Asian and Hispanic ethnicities had reduced pain scores in some functional status scenarios. Conclusion Patients with IIMs reported higher pain levels than wAIDs, but less than patients with other AIRDs. Pain is a disabling manifestation of IIMs and is associated with a poor functional status.HC is supported by the National Institution for Health Research Manchester Biomedical Research Centre Funding Scheme

Interacting circular nanomagnets

Regular 2D rectangular lattices of permalloy nanoparticles (40 nm in diameter) were prepared by the method of the electron lithography. The magnetization curves were studied by Hall magnetometry with the compensation technique for different external field orientations at 4.2K and 77K. The shape of hysteresis curves indicates that there is magnetostatic interaction between the particles. The main peculiarity is the existence of remanent magnetization perpendicular to easy plain. By numerical simulation it is shown, that the character of the magnetization reversal is a result of the interplay of the interparticle interaction and the magnetization distribution within the particles (vortex or uniform).Comment: 16 pages, 8 figure

Identification of plant genetic resources with high potential contribution to soil fertility enhancement in the Sahel, with special interest in fallow vegetation

The sandy soil in the Sahel is characterized as low inherent fertility, that is, having nutrient deficiency (total N and available P), low organic matter and high risk of erosion. Under the concept of integrated soil fertility management (ISFM), possible contribution of natural inhabitant plants to the improvement of soil fertility in the Sahel was evaluated. A broad variation in δ 15N values was observed among the plant species commonly found in cropland and fallow land of the Sahelian zone. Annual leguminous herbs, Cassia mimosoides (Caesalpiniaceae) and Alysicarpus ovalifolius (Papilionaceae), had low δ 15N values, showing their higher dependency on biological nitrogen fixation. They will be efficiently utilized as an extensive means of soil fertility management, for example, through more encouraged incorporation into the fallow vegetation. Ctenium elegans, Eragrostis tremula and Schizachyrium exile, greatly dominating annual grass species in the fallow land, though their δ 15N values were high, would contribute to the soil fertility by supplying a significant amount of organic matte

Kink propagation in a two-dimensional curved Josephson junction

We consider the propagation of sine-Gordon kinks in a planar curved strip as a model of nonlinear wave propagation in curved wave guides. The homogeneous Neumann transverse boundary conditions, in the curvilinear coordinates, allow to assume a homogeneous kink solution. Using a simple collective variable approach based on the kink coordinate, we show that curved regions act as potential barriers for the wave and determine the threshold velocity for the kink to cross. The analysis is confirmed by numerical solution of the 2D sine-Gordon equation.Comment: 8 pages, 4 figures (2 in color