Analysis of Corneal Biomechanical Properties in Different Keratotopographic Patterns of Keratoconus.

Purpose: To analyze the frequency of main keratotopographic patterns at the 1st, 2nd, and 3rd stages of keratoconus and investigate corneal biomechanical properties across different patterns. Methods: The study comprised two stages. The first stage was computational-experimental, where we utilized COMSOL Multiphysics® software (COMSOL AB, Stockholm, Sweden) to mathematically model corneal mechanical behavior under intraocular pressure and pulsed air jet action in both normal and keratoconic conditions. The second stage was the clinical phase, during which we retrospectively analyzed the examination results of both healthy subjects and patients with keratoconus. In total, the study included 256 eyes (256 subjects). Among them, 174 eyes (174 healthy individuals) had normal corneas with different refractions, and 82 eyes (82 individuals) had stages 1, 2, and 3 of keratoconus based on Amsler-Krumeich classification. The keratotopographic characteristics of the participants were assessed using Sirius (Schwind, Germany) and Pentacam AXL (OCULUS Optikgeräte GmbH, Germany) keratotomographs, while the corneal biomechanical properties were studied using noncontact tonometry with the Corvis ST device (OCULUS Optikgeräte GmbH, Germany). The study focused on evaluating corneal stiffness index values in the central optical zone under various keratotopographic patterns. In addition, it compared the elastic coefficient values c1, c2, and c3 for the model of hyperelastic behavior of corneal material outside the keratoconus zone. Furthermore, the study examined the values of reduced stiffness zone characteristics, including the stiffness reduction factor ψmax, effective radius Rk, and the ratio of maximum and minimum strain intensity in keratoconus of different stages. Results: The mean age of the patients in the study was 30.16 ± 8.31 years, with 166 men and 90 women participating. The study revealed typical keratotopographic patterns in the examined keratoconus stages, as well as their occurrence frequency. In the 1st stage of keratoconus, the pattern of asymmetric astigmatism was noted more frequently (in 75% of cases). In the 2nd stage, the pattern with an ectasia zone in the lower cornea was observed in 80% of cases, and in the 3rd stage, a centrally located keratotopographic ectasia pattern was found in 42% of cases. Comparative analysis showed that the greatest decrease in stiffness parameter (SpA1) and stress-strain index occurred in the central pattern (by 64% and 46%, respectively), while the least decrease was observed in local corneal radius reduction in the lower cornea (by 42% and 33%, respectively). Conclusions: The decrease in strength properties in keratoconus occurs in a local area, the size and degree of which are determined by the disease stage. The indicated biomechanical parameters are consistent regardless of the shape and localization of keratotopographic patterns but are relevant to diagnostic specifications using the Corvis ST pneumotonometer, which assesses corneal properties in the apical zone.

Integrated Platform for the Management of Chronic Low Back Pain.

BACKGROUND: Chronic low back pain is a global health problem having a tremendous effect on the quality of life of patients. OBJECTIVES: An online therapy management system (TMS) is developed for comprehensive management of chronic low back pain patients. METHODS: A smartphone and a web app are built based on the Keep-In-Touch Telehealth Platform. The smartphone app allows entering patient reported outcomes and connection to third party devices to monitor physiological data and parameters of therapy. RESULTS: The TMS has been realized and a wearable auricular vagus nerve stimulation device has been integrated. The TMS is currently evaluated in a randomized clinical trial.

Ruptured tuberculous aneurysms of the abdominal aorta: Two case series.

BACKGROUND: Ruptured aneurysms secondary to the tuberculous infection of the aorta are a rare and life-threatening disease. We report a single-center experience of two patients with ruptured infrarenal tuberculous aneurysms. CASE PRESENTATION: We report 2 patients with ruptures of the tuberculous aneurysm. All patients had acute abdominal pain and were diagnosed by echography then CT scan preoperatively. The first patient (male, 50 years old) had a ruptured saccular aneurysm. The second patient (male, 43 years old) had a retroperitoneal contained rupture. All were treated by open prosthetic repair, by vascular surgeons. The two patients were well after operations. The diagnosis was confirmed by pathology examination. Antituberculous treatment was introduced after the operation. CONCLUSIONS: Ruptured tuberculous aneurysms are rare but life-threatening. The diagnosis requires a high degree of suspicion. The treatment includes early diagnosis and emergent surgical intervention, extensive excision of infected field, aortic reconstruction, and prolonged antituberculous drug therapy.

Effect of multiple rescatterings on continuum harmonics from asymmetric molecules in multicycle lasers.

A wide range of harmonics especially continuum harmonics is a prerequisite for attosecond pulse generation. One can use longer-wavelength lasers to push the cutoff to a higher order. However, this does not translate to the same amount of continuum range extension because multiple rescattering phenomena are also enhanced in the process, potentially affecting the lower end of the continuum harmonics. It is then important to understand exactly how multiple rescatterings affect the harmonic structure and their response to various laser parameters, which is the main theme of this paper. Particularly, by applying the synchrosqueezed time-frequency transform and classical electron trajectory analysis to the asymmetric molecule carbon monoxide (CO), we justify that the multiple rescatterings indeed influence the periodicity of the harmonic spectra and the stable periodicity is, in fact, bounded by the first- and third-order returns. Moreover, for the first time, we find that the high-order rescatterings are asymmetric regarding the molecular rotation of 180°, but always correlate with the first-order returns. Our last result is that by breaking the laser symmetry in an appropriate way, the contribution of multiple rescatterings is removed so that the continuum region is entirely defined by the first-order return energies.

High-Resolution Episcopic Imaging for Visualization of Dermal Arteries and Nerves of the Auricular Cymba Conchae in Humans.

Therapeutic applications of auricular vagus nerve stimulation (VNS) have drawn recent attention. Since the targeted stimulation process and parameters depend on the electrode-tissue interaction, the lack of structural anatomical information on innervation and vascularization of the auricle restrain the current optimization of stimulation paradigms. For the first time, we employed high-resolution episcopic imaging (HREM) to generate histologic volume data from donated human cadaver ears. Optimal parameters for specimen preparation were evaluated. Anatomical 3D vascular and nerve structures were reconstructed in one sample of an auricular cymba conchae (CC). The feasibility of HREM to visualize anatomical structures was assessed in that diameters, occupied areas, volumes, and mutual distances between auricular arteries, nerves, and veins were registered. The selected region of CC (3 × 5.5 mm) showed in its cross-sections 21.7 ± 2.7 (mean ± standard deviation) arteries and 14.66 ± 2.74 nerve fibers. Identified nerve diameters were 33.66 ± 21.71 µm, and arteries had diameters in the range of 71.58 ± 80.70 µm. The respective occupied area showed a share of, on average, 2.71% and 0.3% for arteries and nerves, respectively, and similar volume occupancy for arteries and nerves. Inter-centroid minimum distance between arteries and nerves was 274 ± 222 µm. The density of vessels and nerves around a point within CC on a given grid was assessed, showing that 50% of all vessels and nerves were found in a radial distance of 1.6-1.8 mm from any of these points, which is strategically relevant when using stimulation needles in the auricle for excitation of nerves. HREM seems suitable for anatomical studies of the human ear. A 3D model of CC was established in the micrometer scale, which forms the basis for future optimization of the auricular VNS. Obviously, the presented single cadaver study needs to be validated by additional anatomical data on the innervation and vascularization of the auricle.

Orbital magnetization in axially symmetric two-dimensional carbon allotrope: influence of electric field and geometry.

In this paper, we use supersymmetry formalism to study (2 + 1) dimensional Dirac-Weyl equation describing the motion of electrons in different axially symmetric carbon allotrope surfaces under the influence of crossed electromagnetic fields. In particular, we consider three carbon allotrope with different geometrical shapes and properties: open, half-open and closed geometries. The effect of the electric field and geometry on Landau levels and orbital magnetization has been examined. It has been shown that at a critical electric field the orbital magnetization exhibits a discontinuity which is associated with the collapse of Landau levels.

Odd-even harmonic generation from oriented CO molecules in linearly polarized laser fields and the influence of the dynamic core-electron polarization.

We present a detailed theoretical study of the odd-even harmonics generated from the polar molecule CO by the method based on numerically solving the time-dependent Schrödinger equation within the single-active-electron approximation. First, we reproduce the pure even harmonic generation of CO predicted theoretically by Hu et al. using the time-dependent density functional theory [H. Hu et al., Phys. Rev. Lett., 2017, 119, 173201]. Then, based on the Floquet approach, we are able to attribute this behavior to the half-cycle mirror symmetry of the molecule-field system when the polar molecule is perpendicular to the laser polarization. By numerical simulations, we show that this symmetry is broken at orientation angles other than 90° resulting in the odd-even harmonic generation and a non-trivial even-to-odd harmonics ratio strongly dependent on the molecular orientation. Furthermore, we investigate the influence of the dynamic core-electron polarization (DCeP) on the odd-even behavior near the cutoff of the high-order harmonic spectra. We emphasize that the DCeP effect is noticeable for the odd harmonics only.

Electric field and curvature effects on relativistic Landau levels on a pseudosphere.

In this paper relativistic Landau levels on a carbon pseudosphere, whose curvature is a negative constant K = -R -2, are investigated analytically in the presence of orthogonal electric and magnetic fields. It has been shown that the magnetic field tends to create bound states while the electric field tends to destroy them. Consequently there exists a critical electric field such that beyond this critical field the Landau levels collapse although negative curvature of the pseudosphere acts towards preventing the collapse of Landau levels at the critical value.