All-metal beam steering antenna based on the concept of Risley prism is presented in this communication. The antenna is composed of a feed antenna and two metal lenses. Mechanically rotate two lenses ...along the same axis independently can steer the radiation beam in both azimuth and elevation planes. Simulations and measurements were carried out in X-band to verify its performance, and the results agree each other well, which are also in agreement with the theoretical results. Furthermore, the power handling capability of the lens antenna with a dimension of 1 m × 1 m is estimated about 4 GW, which indicates the all-metal beam steering antenna has the application potentials for high-power microwave applications.
Sleep architecture carries vital information about brain health across the lifespan. In particular, the ability to express distinct vigilance states is a key physiological marker of neurological ...wellbeing in the newborn infant although systems-level mechanisms remain elusive. Here, we demonstrate that the transition from quiet to active sleep in newborn infants is marked by a substantial reorganization of large-scale cortical activity and functional brain networks. This reorganization is attenuated in preterm infants and predicts visual performance at two years. We find a striking match between these empirical effects and a computational model of large-scale brain states which uncovers fundamental biophysical mechanisms not evident from inspection of the data. Active sleep is defined by reduced energy in a uniform mode of neural activity and increased energy in two more complex anteroposterior modes. Preterm-born infants show a deficit in this sleep-related reorganization of modal energy that carries novel prognostic information.
With the rapid popularization of wireless electronic devices, there has been an increasing concern about the impacts of the electromagnetic environment on health. However, most research reports on ...the biological effects of microwaves have focused on a single frequency point. In reality, people are exposed to complex electromagnetic environments that consist of multiple frequency microwave signals in their daily lives. It is important to investigate whether multi-frequency combined microwave energies have different biological effects compared with single frequency microwave energy. Unfortunately, there are limited reports on this topic due to the lack of suitable platforms for research on multi-frequency microwave energy combined with biological exposure. To address this issue, this study presents a setup that has a very wide working frequency bandwidth and can be compatible with single frequency and multi-frequency microwave combined exposure. Moreover, it can achieve relatively equal exposure to multiple biological samples at any frequency point in the working frequency range, which is crucial for electromagnetic biology research. The experimental results are in good agreement with the simulation results, confirming its capability to facilitate the study of complex electromagnetic environment effects on organisms.
OBJECTIVETo determine whether quantitative EEG (QEEG) features predict neurologic outcomes in children after cardiac arrest.
METHODSWe performed a single-center prospective observational study of 87 ...consecutive children resuscitated and admitted to the pediatric intensive care unit after cardiac arrest. Full-array conventional EEG data were obtained as part of clinical management. We computed 8 QEEG features from 5-minute epochs every hour after return of circulation. We developed predictive models utilizing random forest classifiers trained on patient age and 8 QEEG features to predict outcome. The features included SD of each EEG channel, normalized band power in alpha, beta, theta, delta, and gamma wave frequencies, line length, and regularity function scores. We measured outcomes using Pediatric Cerebral Performance Category (PCPC) scores. We evaluated the models using 5-fold cross-validation and 1,000 bootstrap samples.
RESULTSThe best performing model had a 5-fold cross-validation accuracy of 0.8 (0.88 area under the receiver operating characteristic curve). It had a positive predictive value of 0.79 and a sensitivity of 0.84 in predicting patients with favorable outcomes (PCPC score of 1–3). It had a negative predictive value of 0.8 and a specificity of 0.75 in predicting patients with unfavorable outcomes (PCPC score of 4–6). The model also identified the relative importance of each feature. Analyses using only frontal electrodes did not differ in prediction performance compared to analyses using all electrodes.
CONCLUSIONSQEEG features can standardize EEG interpretation and predict neurologic outcomes in children after cardiac arrest.
Transmit-array (T-A) design for circular polarization made by all metal is presented in this communication. The proposed T-A consists of numerous cross-slot elements. The simulation results indicate ...that rotating the cross slot on the element, a full transmission phase range of 360° can be achieved for a transmission magnitude better than -0.6 dB at 9.375 GHz. A T-A has been designed, simulated, and measured in x-band. The measurement results show that the T-A can radiate the wave in the desired direction with an enhanced gain. They are in agreement with the theoretical and simulation results. Furthermore, the all-metal T-A presented in this communication has the application potentials for high-power microwave applications.
This study aimed to elucidate the effects and biological targets sensitive to simultaneous 1.5 and 4.3 GHz microwave exposure in rats. A total of 120 male Wistar rats were divided randomly into four ...groups: the sham (S group), 1.5 GHz microwave exposure (L group), 4.3 GHz microwave exposure (C group) and simultaneous 1.5 and 4.3 GHz microwave exposure (LC group) groups. Spatial learning and memory, cortical electrical activity, and hippocampal ultrastructure were assessed by the Morris Water Maze, electroencephalography, and transmission electron microscopy, respectively. Additionally, serum exosomes were isolated by ultracentrifugation and assessed by Western blotting, nanoparticle tracking and transmission electron microscopy. The serum exosome protein content was assessed by label-free quantitative proteomics. Impaired spatial learning and memory decreased cortical excitability, and damage to the hippocampal ultrastructure were observed in groups exposed to microwaves, especially the L and LC groups. A total of 54, 145 and 296 exosomal proteins were differentially expressed between the S group and the L, C and LC groups, respectively. These differentially expressed proteins were involved in the synaptic vesicle cycle and SNARE interactions during vesicular transport. Additionally, VAMP8, Syn7 and VMAT are potential serum markers of simultaneous microwave exposure. Thus, exposure to 1.5 and 4.3 GHz microwaves induced impairments in spatial learning and memory, and simultaneous microwave exposure had the most severe effects.
•A microwave source with simultaneous exposure of 1.5 GHz and 4.3 GHz was constructed.•The simultaneous microwave could induced early impairments spatial learning and memory abilities and hippocampal structure.•VAMP8, Syn7, VMAT might be key molecules in serum exosomes for microwave exposure.
This study presents the design and simulation of a novel type of TM01-TE01 mode converter for high-power microwave applications, which efficiently converts the TM01 circular waveguide mode into the ...TE01 circular waveguide mode. The converter is composed of three sections: power-dividing section, twist-waveguide section and power-combining section. These sections were analyzed and discussed respectively, and the whole converter structure was studied numerically. The results show that at the central frequency 12.5 GHz, the TM01-TE01 conversion loss of the converter made of aluminum is 0.05 dB and the bandwidth for S21 > 0.25 dB is 2.73 GHz. Moreover, the power-handling capacity is over 2 GW.
The solution utilized to design a compact transverse electromagnetic mode (TEM)-CPT (circular polarized TE11) mode converter with high power handling capability and high efficiency, especially at ...high frequency bands is proposed in this paper. The analysis shows that increasing the quantity of the arms of the converter could make the converter work under overmoded state. The problem that the power capability of the converter working at high frequency bands is low will be addressed. To verify the feasibility of this solution, simulations and experiments on a 20 arms converter are carried out, and the results show that the converter would convert the TEM mode into CPT mode efficiently in a 2-3 free wavelengths longitudinal size and that the power capability is in gigawatt (GW) class. Moreover, this kind of converter can also be utilized in the design of GW TEM phase shifter, whether at low or high frequency bands, which plays a key role in the power combining technology.
Objective. Closed-loop implantable neural stimulators are an exciting treatment option for patients with medically refractory epilepsy, with a number of new devices in or nearing clinical trials. ...These devices must accurately detect a variety of seizure types in order to reliably deliver therapeutic stimulation. While effective, broadly-applicable seizure detection algorithms have recently been published, these methods are too computationally intensive to be directly deployed in an implantable device. We demonstrate a strategy that couples devices to cloud computing resources in order to implement complex seizure detection methods on an implantable device platform. Approach. We use a sensitive gating algorithm capable of running on-board a device to identify potential seizure epochs and transmit these epochs to a cloud-based analysis platform. A precise seizure detection algorithm is then applied to the candidate epochs, leveraging cloud computing resources for accurate seizure event detection. This seizure detection strategy was developed and tested on eleven human implanted device recordings generated using the NeuroVista Seizure Advisory System. Main results. The gating algorithm achieved high-sensitivity detection using a small feature set as input to a linear classifier, compatible with the computational capability of next-generation implantable devices. The cloud-based precision algorithm successfully identified all seizures transmitted by the gating algorithm while significantly reducing the false positive rate. Across all subjects, this joint approach detected 99% of seizures with a false positive rate of 0.03 h−1. Significance. We present a novel framework for implementing computationally intensive algorithms on human data recorded from an implanted device. By using telemetry to intelligently access cloud-based computational resources, the next generation of neuro-implantable devices will leverage sophisticated algorithms with potential to greatly improve device performance and patient outcomes.
A user ready, portable, documented software package, NFTsim, is presented to facilitate numerical simulations of a wide range of brain systems using continuum neural field modeling. NFTsim enables ...users to simulate key aspects of brain activity at multiple scales. At the microscopic scale, it incorporates characteristics of local interactions between cells, neurotransmitter effects, synaptodendritic delays and feedbacks. At the mesoscopic scale, it incorporates information about medium to large scale axonal ranges of fibers, which are essential to model dissipative wave transmission and to produce synchronous oscillations and associated cross-correlation patterns as observed in local field potential recordings of active tissue. At the scale of the whole brain, NFTsim allows for the inclusion of long range pathways, such as thalamocortical projections, when generating macroscopic activity fields. The multiscale nature of the neural activity produced by NFTsim has the potential to enable the modeling of resulting quantities measurable via various neuroimaging techniques. In this work, we give a comprehensive description of the design and implementation of the software. Due to its modularity and flexibility, NFTsim enables the systematic study of an unlimited number of neural systems with multiple neural populations under a unified framework and allows for direct comparison with analytic and experimental predictions. The code is written in C++ and bundled with Matlab routines for a rapid quantitative analysis and visualization of the outputs. The output of NFTsim is stored in plain text file enabling users to select from a broad range of tools for offline analysis. This software enables a wide and convenient use of powerful physiologically-based neural field approaches to brain modeling. NFTsim is distributed under the Apache 2.0 license.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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