Feasibility of Simultaneous Anodal Transcranial Direct Current Stimulation During Gait Training in Chronic Stroke Patients: A Randomized Double-Blind Pilot Clinical Trial.

BACKGROUND: Transcranial direct current stimulation (tDCS) is a therapeutic tool for improving post-stroke gait disturbances, with ongoing research focusing on specific protocols for its application. We evaluated the feasibility of a rehabilitation protocol that combines tDCS with conventional gait training. METHODS: This was a randomized, double-blind, single-center pilot clinical trial. Patients with unilateral hemiplegia due to ischemic stroke were randomly assigned to either the tDCS with gait training group or the sham stimulation group. The anodal tDCS electrode was placed on the tibialis anterior area of the precentral gyrus while gait training proceeded. Interventions were administered 3 times weekly for 4 weeks. Outcome assessments, using the 10-meter walk test, Timed Up and Go test, Berg Balance Scale, Functional Ambulatory Scale, Modified Barthel Index, and European Quality of Life 5 Dimensions 3 Level Version, were conducted before and after the intervention and again at the 8-week mark following its completion. Repeated-measures analysis of variance (ANOVA) was used for comparisons between and within groups. RESULTS: Twenty-six patients were assessed for eligibility, and 20 were enrolled and randomized. No significant differences were observed between the tDCS with gait training group and the sham stimulation group in gait speed after the intervention. However, the tDCS with gait training group showed significant improvement in balance performance in both within-group and between-group comparisons. In the subgroup analysis of patients with elicited motor-evoked potentials, comfortable pace gait speed improved in the tDCS with gait training group. No serious adverse events occurred throughout the study. CONCLUSIONS: Simultaneous anodal tDCS during gait training is a feasible rehabilitation protocol for chronic stroke patients with gait disturbances. CLINICAL TRIAL REGISTRATION: URL: https://cris.nih.go.kr; Registration number: KCT0007601; Date of registration: 11 July 2022.

Capacitive Electrode-Based Electric Field Treatments on Redox-Toxic Iron Deposits in Transgenic AD Mouse Models: The Electroceutical Targeting of Alzheimer's Disease Feasibility Study.

Iron accumulation in the brain accelerates Alzheimer's disease progression. To cure iron toxicity, we assessed the therapeutic effects of noncontact transcranial electric field stimulation to the brain on toxic iron deposits in either the Aß fibril structure or the Aß plaque in a mouse model of Alzheimer's disease (AD) as a pilot study. A capacitive electrode-based alternating electric field (AEF) was applied to a suspension of magnetite (Fe3O4) to measure field-sensitized reactive oxygen species (ROS) generation. The increase in ROS generation compared to the untreated control was both exposure-time and AEF-frequency dependent. The frequency-specific exposure of AEF to 0.7-1.4 V/cm on a magnetite-bound Aß-fibril or a transgenic Alzheimer's disease (AD) mouse model revealed the degradation of the Aß fibril or the removal of the Aß-plaque burden and ferrous magnetite compared to the untreated control. The results of the behavioral tests show an improvement in impaired cognitive function following AEF treatment on the AD mouse model. Tissue clearing and 3D-imaging analysis revealed no induced damage to the neuronal structures of normal brain tissue following AEF treatment. In conclusion, our results suggest that the effective degradation of magnetite-bound amyloid fibrils or plaques in the AD brain by the electro-Fenton effect from electric field-sensitized magnetite offers a potential electroceutical treatment option for AD.

Control of localization and optical properties with deep-subwavelength engineered disorder.

The effect of deep subwavelength disorder in one-dimensional dichromic multilayer films on the optical transmission, localization length, and Goos-Hänchen shift around the critical angle is analyzed using sets of disordered multilayer films with different degrees of order metric τ. For each Gaussian-perturbed multilayer film designed by a Metropolis algorithm targeting the predetermined order metric τ, the numerically obtained localization length and transmission show excellent agreement with the recent theoretical analysis developed for disordered multilayer films, further revealing τ-dependence of the Goos-Hänchen shift across the critical angle. Emphasizing the role of deep subwavelength structures in disorder-induced transmission enhancement, our result thus paves the way toward the inverse design of a deep subwavelength disordered structural landscape for the targeted order metric τ or abnormal optical responses - including the Goos-Hänchen shift.

A boy with a congenital cerebellar mass.

PURPOSE: Tumorigenesis of medulloblastoma is believed to be associated with granule cell progenitor neurogenesis of the cerebellum. Nevertheless, congenital medulloblastomas are rarely found. Here, we report a case of congenital medulloblastoma that showed spontaneous albeit transient regression. METHODS: A one-month-old baby presented with abnormal antenatal and postnatal imaging findings. Upon ultrasonography at 26 weeks of gestational age, Dandy-Walker malformation with vermian hypoplasia and cystic change was suspected. Brain MRI at 1 week after birth revealed gadolinium-enhancing lesions in the cerebellum with apparent infiltrative features along the cerebellar folia accompanied by three independent cysts in the upper and inferolateral sides of the lesion. Serial MRIs taken up to 5 months of age showed a decrease in the size and extent of enhancing solid portions. The baby did not show any abnormal signs or developmental delay. MRI at the age of 7 months showed enlargement of the lesion, and surgery was performed. RESULTS: The lesion was diagnosed as medulloblastoma with histologically extensive nodularity (MBEN), genetically SHH-activated and TP53-wildtype. CONCLUSION: This case provides an unusual chance of observing an early phase of medulloblastoma development and raises a suspicion that medulloblastoma may initiate itself very early in cerebellar organogenesis and progress later at a certain time of postnatal development.

Long-term clinical outcomes in patients with untreated non-culprit intermediate coronary lesion and evaluation of predictors by using virtual histology-intravascular ultrasound; a prospective cohort study.

BACKGROUND: It is uncertain whether the coronary lesion with intermediate stenosis is more likely to cause cardiovascular events than a normal or minimal lesion. We conducted a single-center, prospective cohort study to identify long-term clinical outcomes of patients with untreated non-culprit intermediate lesion and evaluate its predictor of cardiovascular events by using virtual histology-intravascular ultrasound (VH-IVUS). METHODS: Subjects with non-culprit intermediate lesion underwent VH-IVUS were prospectively registered after percutaneous coronary intervention at the culprit lesion. Intermediate lesion was defined as 30 to 70% stenosis in coronary angiography and primary outcome was an occurrence of major adverse cardiovascular events (MACE) defined as all-cause death, intermediate lesion revascularization (InLR), minimal lesion revascularization (MnLR, unplanned revascularization elsewhere in the target vessel or in other coronary arteries which looked normal or minimal stenosis), cerebrovascular events, or non-fatal myocardial infarction (MI). The mean follow-up period was 4.2 years. RESULTS: Total 25 MACE, approximately 7% incidence annually, were identified during a follow-up period in 86 patients with 89 intermediate lesions. InLR (n = 13) was a most common event followed by MnLR (n = 6), non-fatal MI (n = 4), all-cause death (n = 3), and cerebrovascular events (n = 1). Diameter stenosis (OR 1.07, 95% CI 1.01-1.12, p = 0.015), plaque burden (PB, OR 1.07, 95% CI 1.00-1.15, p = 0.040), fibrofatty area (FFA, OR 1.61, 95% CI 1.10-2.38, p = 0.016), PB ≥ 70% (OR 3.93, 95% CI 1.28-12.07, p = 0.018), and area stenosis ≥ 50% (OR 2.94, 95% CI 1.01-8.56, p = 0.042) showed significant relationships with an occurrence of MACE. In multivariable Cox-proportional hazard analysis, FFA in intermediate lesion was an only independent predictor of MACE (HR 1.36, 95% CI 1.05-1.77, p = 0.019). CONCLUSIONS: Untreated intermediate lesions had a significantly higher chance for requiring revascularization compared with a normal or minimal lesion. And also, a large FFA in intermediate lesion was a significant predictor of cardiovascular events and which finding was mainly driven by coronary-related events, in particularly intermediate lesion progression.

Resonant absorption of electromagnetic waves in transition anisotropic media.

We study the mode conversion and resonant absorption phenomena occurring in a slab of a stratified anisotropic medium, optical axes of which are tilted with respect to the direction of inhomogeneity, using the invariant imbedding theory of wave propagation. When the tilt angle is zero, mode conversion occurs if the longitudinal component of the permittivity tensor, which is the one in the direction of inhomogeneity in the non-tilted case, varies from positive to negative values within the medium, while the transverse component plays no role. When the tilt angle is nonzero, the wave transmission and absorption show an asymmetry under the sign change of the incident angle in a range of the tilt angle, while the reflection is always symmetric. We calculate the reflectance, the transmittance and the absorptance for several configurations of the permittivity tensor and find that resonant absorption is greatly enhanced when the medium from the incident surface to the resonance region is hyperbolic than when it is elliptic. For certain configurations, the transmittance and absorptance curves display sharp peaks at some incident angles determined by the tilt angle.

Giant enhancement of reflectance due to the interplay between surface confined wave modes and nonlinear gain in dielectric media.

We study theoretically the interplay between the surface confined wave modes and the linear and nonlinear gain of the dielectric layer in the Otto configuration. The surface confined wave modes, such as surface plasmons or waveguide modes, are excited in the dielectric-metal bilayer by obliquely incident p waves. In the purely linear case, we find that the interplay between linear gain and surface confined wave modes can generate a large reflectance peak with its value much greater than 1. As the linear gain parameter increases, the peak appears at smaller incident angles, and the associated modes also change from surface plasmons to waveguide modes. When the nonlinear gain is turned on, the reflectance shows very strong multistability near the incident angles associated with surface confined wave modes. As the nonlinear gain parameter is varied, the reflectance curve undergoes complicated topological changes and sometimes displays separated closed curves. When the nonlinear gain parameter takes an optimally small value, a giant amplification of the reflectance by three orders of magnitude occurs near the incident angle associated with a waveguide mode. We also find that there exists a range of the incident angle where the wave is dissipated rather than amplified even in the presence of gain. We suggest that this can provide the basis for a possible new technology for thermal control in the subwavelength scale.

Multifunctional Woven Structure Operating as Triboelectric Energy Harvester, Capacitive Tactile Sensor Array, and Piezoresistive Strain Sensor Array.

This paper presents a power-generating sensor array in a flexible and stretchable form. The proposed device is composed of resistive strain sensors, capacitive tactile sensors, and a triboelectric energy harvester in a single platform. The device is implemented in a woven textile structure by using proposed functional threads. A single functional thread is composed of a flexible hollow tube coated with silver nanowires on the outer surface and a conductive silver thread inside the tube. The total size of the device is 60 × 60 mm² having a 5 × 5 array of sensor cell. The touch force in the vertical direction can be sensed by measuring the capacitance between the warp and weft functional threads. In addition, because silver nanowire layers provide piezoresistivity, the strain applied in the lateral direction can be detected by measuring the resistance of each thread. Last, with regard to the energy harvester, the maximum power and power density were measured as 201 µW and 0.48 W/m², respectively, when the device was pushed in the vertical direction.

Resonant absorption and amplification of circularly-polarized waves in inhomogeneous chiral media.

It has been found that in the media where the dielectric permittivity ε or the magnetic permeability µ is near zero and in transition metamaterials where ε or µ changes from positive to negative values, there occur a strong absorption or amplification of the electromagnetic wave energy in the presence of an infinitesimally small damping or gain and a strong enhancement of the electromagnetic fields. We attribute these phenomena to the mode conversion of transverse electromagnetic waves into longitudinal plasma oscillations and its inverse process. In this paper, we study analogous phenomena occurring in chiral media theoretically using the invariant imbedding method. In uniform isotropic chiral media, right-circularly-polarized and left-circularly-polarized waves are the eigen-modes of propagation with different effective refractive indices n(+) and n(-), whereas in the chiral media with a nonuniform impedance variation, they are no longer the eigenmodes and are coupled to each other. We find that both in uniform chiral slabs where either n(+) or n(-) is near zero and in chiral transition metamaterials where n(+) or n(-) changes from positive to negative values, a strong absorption or amplification of circularly-polarized waves occurs in the presence of an infinitesimally small damping or gain. We present detailed calculations of the mode conversion coefficient, which measures the fraction of the electromagnetic wave energy absorbed into the medium, for various configurations of ε and µ with an emphasis on the influence of a nonuniform impedance. We propose possible applications of these phenomena to linear and nonlinear optical devices that react selectively to the helicity of the circular polarization.

Excitation of surface waves on the interfaces of general bi-isotropic media.

We study theoretically the characteristics of surface waves excited at the interface between a metal and a general bi-isotropic medium, which includes isotropic chiral media and Tellegen media as special cases. We derive an analytical dispersion relation for surface waves, using which we calculate the effective index and the propagation length numerically. We also calculate the absorptance, the cross-polarized reflectance and the spatial distribution of the electromagnetic fields for plane waves incident on a bilayer system consisting of a metal layer and a bi-isotropic layer in the Kretschmann configuration, using the invariant imbedding method. The results obtained using the invariant imbedding method agree with those obtained from the dispersion relation perfectly. In the case of chiral media, the effective index is an increasing function of the chirality index, whereas in Tellegen media, it is a decreasing function of the Tellegen parameter. The propagation length for surface waves in both cases increase substantially as either the chirality index or the Tellegen parameter increases. In Tellegen media, it diverges to infinity when the effective index goes to zero, whereas in chiral media, it does when the parameters approach the cutoff values where quasi surface waves are excited. We investigate the characteristics of quasi surface waves excited when the chirality index is sufficiently large.