Design and Analysis of a Triple-band Non-zonal Polarization Electromagnetic Metamaterial Absorber

A facile design of a novel triple-band electromagnetic metamaterial absorber (MMA) with polarization insensitive property is proposed in this paper. Each unit of the MMA consists of upper copper resonator and bottom copper plate with middle dielectric FR-4 between them. The MMA performs three absorption peaks at 16.919 GHz, 21.084 GHz and 25.266 GHz with absorption rates 99.90%, 97.76% and 99.18%, respectively. The influence of the main structural parameters on the frequencies and absorption rates is analyzed. The absorption mechanism of the absorber is explained by electric field, magnetic field and surface current distributions, which is supported by the electromagnetic parameters, affected with magnetic resonance. The polarization-insensitivity of TE wave is verified by observing the effects of the polarization angle change from 0-90º. The MMA can be applied in radiation, spectrum imaging detector, electromagnetic wave modulator, and so on.

Characterization of multiple sclerosis neuroinflammation and neurodegeneration with relaxation and diffusion basis spectrum imaging

Background: Advanced magnetic resonance imaging (MRI) methods can provide more specific information about various microstructural tissue changes in multiple sclerosis (MS) brain. Quantitative measurement of T1 and T2 relaxation, and diffusion basis spectrum imaging (DBSI) yield metrics related to the pathology of neuroinflammation and neurodegeneration that occurs across the spectrum of MS. Objective: To use relaxation and DBSI MRI metrics to describe measures of neuroinflammation, myelin and axons in different MS subtypes. Methods: 103 participants (20 clinically isolated syndrome (CIS), 33 relapsing-remitting MS (RRMS), 30 secondary progressive MS and 20 primary progressive MS) underwent quantitative T1, T2, DBSI and conventional 3T MRI. Whole brain, normal-appearing white matter, lesion and corpus callosum MRI metrics were compared across MS subtypes. Results: A gradation of MRI metric values was seen from CIS to RRMS to progressive MS. RRMS demonstrated large oedema-related differences, while progressive MS had the most extensive abnormalities in myelin and axonal measures. Conclusion: Relaxation and DBSI-derived MRI measures show differences between MS subtypes related to the severity and composition of underlying tissue damage. RRMS showed oedema, demyelination and axonal loss compared with CIS. Progressive MS had even more evidence of increased oedema, demyelination and axonal loss compared with CIS and RRMS.

Characterisation of Dentatorubrothalamic tract with Diffusion Spectrum Imaging in Patients suffering from Parkinson’s disease

Introduction: Clinical data support that the dentatorubrothalamic tract (DRTT) is an effective target for deep brain stimulation (DBS) in medically refractory tremor. Nevertheless, the achievement of a realistically detailed depiction of DRTT for preoperative direct targeting remains a challenge.Methods: Ten patients with Parkinson’s disease from the Inselspital Bern database were selected. We used diffusion spectrum imaging (DSI) scans for deterministic fiber tracking of the DRTT with the Track Vis software. Thereafter we compared our DSI-characterized DRTT with the existing anatomical data.Results: In 6 out of 10 individuals the full course of DRTT has been in high affiliation/consistency/association/adherence with the anatomical course of DRTT as described in literature.Conclusions: In this study DSI fiber tracking was used to characterize successfully the DRTT anatomical course in its complexity in a quest of the optimal DBS target for parkinsonian tremor. To our knowledge such attempt has not occurred before. Further studies are required to standardize the protocol of DRTT fiber Tracking and to implement it as a valid DBS preoperative planning technique.