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Maintaining acceptable radiation performance over the entire operation bandwidth is a significant challenge in development of a miniaturised reconfigurable antenna. To address this issue, a new Substrate Integrated Waveguide (SIW) based reconfigurable antenna using slow wave structure is presented in this study. The proposed SIW antenna is based on a layered construction with metallic blind vias connecting to ground plane of SIW. The multi-layer structure of SIW with blind vias helps to separate magnetic and electric fields in the SIW cavity. Thus, a slow wave effect is also utilised and it leads to 36% reduction in the antenna size as compared to conventional SIW cavity. To attain the polarisation and frequency reconfiguration, a cross slot is introduced in the top metallic layer of the SIW cavity and four PIN diodes are connected into the cross-slot arms. Experimental results exhibit frequency reconfigurability in different operating regions with resonant frequencies 4.35, 5, 5.8, 6.4, and 9.6 GHz. The polarisation reconfigurability of the proposed antenna is achieved at 5 GHz with LP/RHCP/LHCP. The proposed antenna exhibits 3-dB axial ratio bandwidth of 4.8 to 5.2 GHz with peak gain of 4.2 dBi. [ABSTRACT FROM AUTHOR]

Background: The unexpected observation of calretinin immunoreactivity in smooth muscle cells in the muscularis propria of the cecum led to a more detailed examination of calretinin expression and its possible relationship to propulsive contractile activity around the vermiform appendix. Methods: Immunohistochemistry and RNA in situ hybridization were performed to analyze calretinin expression in intestinal samples from 33 patients at ages ranging from mid-gestation fetuses to adults, as well as in some potentially relevant animal models. Dual immunolabeling was done to compare calretinin localization with markers of smooth muscle and interstitial cells of Cajal. Results: Calretinin expression was observed consistently in the innermost smooth muscle layers of the muscularis interna in the human cecum, appendiceal base, and proximal ascending colon, but not elsewhere in the intestinal tract. Calretinin-positive smooth muscle cells did not co-express markers located in adjacent interstitial cells of Cajal. Muscular calretinin immunoreactivity was not detected in the ceca of mice or macaques, species which lack appendices, nor in the rabbit cecum or appendix. Conclusions: Localized expression of calretinin in cecal smooth muscle cells may reduce the likelihood of retrograde, calcium-mediated propulsive contractions from the proximal colon and suppress pro-inflammatory fecal stasis in the appendix. [ABSTRACT FROM AUTHOR]

Intestinal motility is governed in part by bioelectrical slow-waves and spike-bursts. Mesenteric ischemia is a substantial clinical challenge, but its electrophysiological and contractile mechanisms are not well understood. Simultaneous high-resolution bioelectrical and video mapping techniques were used to capture the changes in slow-waves, spike-bursts, and contractile activity during baseline, ischemia, and reperfusion periods. Experiments were performed on anesthetized pigs where intestinal contractions were quantified using surface strain and diameter measurements, while slow-wave and spike-bursts were quantified using frequency and amplitude. Slow-waves entrainment within the ischemic region diminished during ischemia, resulting in irregular slow-wave activity and a reduction in the frequency from 12.4 ± 3.0 cycles-per-minute (cpm) to 2.5 ± 2.7 cpm (p = 0.0006). At the end of the reperfusion period, normal slow-wave entrainment was observed at a frequency of 11.5 ± 2.9 cpm. There was an increase in spike-burst activity between the baseline and ischemia periods (1.1 ± 1.4 cpm to 8.7 ± 3.3 cpm, p = 0.0003) along with a spasm of circumferential contractions. At the end of the reperfusion period, the frequency of spike-bursts decreased to 2.7 ± 1.4 cpm, and contractions subsided. The intestine underwent tonal contraction during ischemia, with the diameter decreasing from 29.3 ± 2.6 mm to 21.2 ± 6.2 mm (p = 0.0020). At the end of the reperfusion period, the intestinal diameter increased to 27.3 ± 3.9 mm. The decrease in slow-wave activity, increase in spike-bursts, and tonal contractions can objectively identify ischemic segments in the intestine. It is anticipated that the use of electrophysiological slow-wave and spike-burst biomarkers, along with contractile measures, could identify mesenteric ischemia in surgical settings and allow an objective biomarker for successful revascularization. [ABSTRACT FROM AUTHOR]

This paper presents a slow‐wave substrate integrated suspended parallel strip line (SW‐SISPSL) for the first time. The slow‐wave effect is produced by cascading high/low‐impedance SISPSL in the meander line configuration. Different from conventional single‐ended slow‐wave transmission lines, the proposed SW‐SISPSL supports differential signal transmission. The characteristic impedance and slow‐wave factor of the SW‐SISPSL are analyzed using equivalent circuit models. Using the proposed SW‐SISPSL and a SISPSL phase inverter, a very compact rat‐race coupler is implemented. The core circuit area of the slow‐wave rat‐race coupler is 0.083 λg × 0.089 λg, which is only 4.12% of the conventional topology. [ABSTRACT FROM AUTHOR]

This paper presents a multi-layered composite right-left-handed (CRLH) slow-wave substrate integrated waveguide (SW-SIW) circularly polarized (CP) leaky-wave antenna (LWA) having wide impedance bandwidth (measured: 14.6–18.25 GHz). The CRLH unit cell consists of three radiating slots on top metallic layer, arranged in a crown-shaped fashion, to achieve wideband circular polarization.The bottom ground plane of the standard SIW is connected to the SW structure of the LWA that consists of internal metalized blind vias. Due to the SW effect, a 33% reduction in lateral dimension is achieved, compared to a conventional SIW having the same cut-off frequency. At the same time, the phase velocity is also reduced leading to a reduction in longitudinal dimensions. The dimensions of the antenna are relatively small, with a size of 3.2 × 0.4x.07 λ3. The operating mechanism of the LWA having symmetrical and continuous backward-to-forward scanning range from −64 ° to 64 ° (128 °) is explained by an equivalent circuit model. The measured CP bandwidth (14.6–18.43 GHz) of the LWA completely overlaps the 10-dB return loss bandwidth. The compact dimension, wide symmetric beam scanning, completely overlapped CP, and return loss bandwidths are the major advantages of the proposed antenna.The LWA exhibits stable gain with a peak value of 11.3 dBic (gain variation: from 9.7 to 11.3 dB). The radiation efficiency of the LWA is above 85% within the impedance bandwidth. [ABSTRACT FROM AUTHOR]

Introduction: Two of the most important ion channels in the smooth muscle membrane are L-type and T-type calcium channels. L-type calcium channels are responsible for smooth muscle contraction, while T-type calcium channels are involved in cell membrane depolarization. Methods: In this study, a model consisting of 1200 cells was used to simulate the smooth muscle of the gastric wall. The paper explores the effects of blocking 10%, 50%, 90%, and 100% of L-type and T-type calcium channels on the spatiotemporal wavefront propagation in human gastric wall smooth muscle cells, simulated separately. Results: The results showed that complete blockage had the most significant effect on the slow-wave. Blockage of the L-type calcium channel led to a reduction of -3.4% and -0.8% in the membrane potential during the spike and plateau phases, respectively. The T-type calcium channel reduced the spike and resting membrane potential by -1.8% and -0.9%, respectively. In addition, the L-type calcium channel exhibited a greater impact on reducing muscle contraction compared to the T-type calcium channel. This suggests that higher blockage of calcium channels led to decreased membrane potential during slow-wave phases and reduced muscle contraction, compared to the physiological state. Conclusion: Blocking ion channels in electrophysiological models can potentially help control gastrointestinal tract motility disorders and smooth muscle contraction. [ABSTRACT FROM AUTHOR]

This paper presents a highly miniaturized tuneable microstrip line phase shifter for 5 GHz to 67 GHz. The design takes advantage of the microstrip topology by substituting the ground plane by a metallic-nanowire-filled porous alumina membrane (NaM). This leads to a slow-wave (SW) effect of the transmission line; thus, the transmission line can be physically compact while maintaining its electric length. By applying a liquid crystal (LC) with its anisotropic permittivity as substrate between the transmission line and the NaM, a tuneable microstrip line phase shifter is realized. Three demonstrators are identically fabricated filled with different types of high-performance microwave LCs from three generations (GT3-23001, GT5-26001 and GT7-29001). The measurement results show good matching in a $50\ \Omega$ system with reflection less than −10 dB over a wide frequency range. These demonstrators are able to reach a maximum figure of merit (FoM) of 41 $^{\circ }$/dB, 48 $^{\circ }$/dB, and 70 $^{\circ }$/dB for different LCs (GT3-23001, GT5-26001 and GT7-29001, respectively). In addition, experiments show that all three LCs should be biased with square wave voltage at approximately 1 kHz to achieve maximum tuneability and response speed. The achieved response times with GT3-23001, GT5-26001 and GT7-29001 are 116 ms, 613 ms, and 125 ms, respectively, which are much faster than other reported LC phase shifter implementations. Large-signal analysis shows that these implementations have high linearity with third-order interception (IP3) points of approximately 60 dBm and a power handling capability of 25 dBm.

In this paper, we describe the design and implementation of a frequency-scanned slotted waveguide antenna with a closed stopband which has a low sensitivity to the fabrication errors. The antenna is implemented as a slotted slow-wave waveguide by loading a standard WR22 waveguide with elliptical posts. A systematic design approach for scanning through broadside and closing the stopband with a reduced sensitivity to fabrication tolerances is discussed in the paper. This approach allows for fabricating the antenna using CNC machining with a tolerance of +/−0.13 mm for the waveguide and a tolerance of +/−0.05 mm for the posts. The antenna beam can be steered from −38° to +27° by changing the frequency from 27 GHz to 34.7 GHz. The effective radiating length of the antenna is $27.6\lambda $ corresponding to a 1.75° half-power beamwidth while its radiation efficiency changes between 54% and 90% throughout the steering range.

Abstract Background Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping. Methods HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 × 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm2, 0.3 mm diameter) for up to 15 min. Passive unipolar signals were obtained and analysed. Results Eleven patients (33–71 years; 6 females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artefact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2 and 6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10–180 s with frequencies of each cluster ranging between 24 and 42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded. Conclusions Intraoperative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity. Although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period. New findings The aim of this study was to assess the feasibility of detecting propagating electrical activity that may correlate to the cyclic motor pattern in the distal human colon through intraoperative, high-resolution, serosal electrical mapping. High-resolution electrical mapping of the human colon revealed no regular propagating activity, but does reveal sporadic spike-wave events. These findings indicate that further research into appropriate techniques is required to identify the mechanism of hyperactive cyclic motor pattern observed in the intra- and post-operative period in humans.

This work presents a novel microwave sensor that is specially designed for the retrieval of complex permittivity. The proposed sensor is designed to operate in the C band (4.54 GHz). By implementing a novel feeding structure, the proposed SIW cavity design improves the coupling and achieves a better quality factor. Several techniques are used to enhance sensitivity, including a Photonic Band Gap (PBG), corner cut, and slow-wave vias. These techniques increase the interaction between the material under test and the electric field. By utilizing slow-wave vias, 35% size reduction is achieved. Achieving simultaneous miniaturization and sensitivity enhancement in this study introduces a new possibility and application for sensor design. The values of complex permittivities are extracted from scattering parameters obtained from simulation of the structure in CST Microwave Studio (MWS) using a machine learning approaches. Our sensor has 0.8% sensitivity, which is better than that of other sensors. Moreover, the maximum error rate in our method is lower than other existing methods. This ratio for the proposed method is 2.31% while for curve fitting and analytical solutions are 26% and 16%, respectively.

In this paper, two types (i.e., type-A and type-B) of hybrid microstrip/defected ground structure (DGS) cells are proposed for passive circuit implementation with ultra-wide stopband. Both cells consist of the stepped-impedance DGS and embedded folded slotline on the ground, which could obtain the dual-resonances. In type-A cell, a microstrip T-stub on the top side is introduced, which can not only allocate a strong coupling to the DGS with slotline on the bottom side, but also act as the input/output port. To finely adjust the dual-resonances of the type-B cell, a grounded microstrip patch is used. Meanwhile, such compact cells could feature an ultra-wide upper stopband, due to their own slow-wave effect. Based on the aforementioned hybrid microstrip/DGS cells, two dual-band bandpass filters (BPFs) and a dual-band filtering power divider (FPD) are proposed and fabricated. Measured and simulated results are in a fairly-close agreement. Both dual-band BPFs exhibit the ultra-wide upper stopband, which extends up to 40 GHz with a high rejection level about 30 dB. Besides, the dual-band FPD has merits of more than 18.7 dB of in-band isolation and 28 dB stopband rejection levels up to 40 GHz.

In this paper we describe the design, theory, implementation, and measurement results of a novel frequency-scanned slow-wave slotted waveguide antenna. The slow-wave antenna is fabricated by periodically loading a standard WR22 waveguide using cylindrical posts. The antenna has a backward radiation and can steer the beam from -72° to -12° by changing the frequency from 32.5 GHz to 37.4 GHz. The gain of the antenna remains within a 3 dB range from the maximum gain of 17 dBi throughout the steering range. The antenna is 29λ in length and 0.69λ in width. The antenna radiation efficiency is between 74% and 92% throughout its frequency range which allows for further extension of its length in order to achieve a higher gain and a smaller beamwidth. Moreover, the small lateral width of the antenna allows placing several of them side-by-side to either narrow or facilitate scanning the beam in the transverse plane. The antenna has a fast and constant scanning rate of 4.3° over a 1% bandwidth and a return loss of less than -10 dB throughout its operating frequency range.

Gastric peristalsis is critically dependent on an underlying electrical conduction system. Recent years have witnessed substantial progress in clarifying the operations of this system, including its pacemaking units, its cellular architecture, and slow-wave propagation patterns. Advanced techniques have been developed for assessing its functions at high spatiotemporal resolutions. This review synthesizes and evaluates this progress, with a focus on human and translational physiology. A current conception of the initiation and conduction of slow-wave activity in the human stomach is provided first, followed by a detailed discussion of its organization at the cellular and tissue level. Particular emphasis is then given to how gastric electrical disorders may contribute to disease states. Gastric dysfunction continues to grow in their prevalence and impact, and while gastric dysrhythmia is established as a clear and pervasive feature in several major gastric disorders, its role in explaining pathophysiology and informing therapy is still emerging. New insights from high-resolution gastric mapping are evaluated, together with historical data from electrogastrography, and the physiological relevance of emerging biomarkers from body surface mapping such as retrograde propagating slow waves. Knowledge gaps requiring further physiological research are highlighted. [ABSTRACT FROM AUTHOR]

Background: Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping.Methods: HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 × 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm2, 0.3 mm diameter) for up to 15 min. Passive unipolar signals were obtained and analysed.Results: Eleven patients (33-71 years; 6 females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artefact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2 and 6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10-180 s with frequencies of each cluster ranging between 24 and 42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded.Conclusions: Intraoperative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity. Although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period.New Findings: The aim of this study was to assess the feasibility of detecting propagating electrical activity that may correlate to the cyclic motor pattern in the distal human colon through intraoperative, high-resolution, serosal electrical mapping. High-resolution electrical mapping of the human colon revealed no regular propagating activity, but does reveal sporadic spike-wave events. These findings indicate that further research into appropriate techniques is required to identify the mechanism of hyperactive cyclic motor pattern observed in the intra- and post-operative period in humans. [ABSTRACT FROM AUTHOR]

Microwave soil heating deactivates weed seeds; however, in many modern agricultural settings, weed seeds are mostly found in the top 1–2 cm of the soil profile. Until recently, microwave soil heating has been achieved using various antennas, which project the microwave energy deeply into the soil. The aim of this research was to develop new microwave applicators that provide shallow heating (less than 50 mm). This paper presents two applicator designs, one based on a comb slow-wave structure and the other on the frustrated total internal reflection (FTIR) principle, which utilise evanescent microwave fields to restrict the depth of microwave heating. The background theory to their performance is presented, followed by experimental evidence of their constrained heating performance under different soil moisture scenarios. Experimental measurements of the heating performance of these applicators, in soils of varying moisture content, demonstrate that the evanescent microwave fields restrict the depth of heating, so that most of the energy is manifested in the top 50 mm of soil. The evanescent field decay rate for the FTIR applicator changes from 44.0 ± 0.7 m−1 to 30 ± 1.2 m−1 as the soil moisture changes from 32% to 174% (dry weight basis). This is higher than the evanescent field decay rate for the comb slow-wave applicator (17.6 ± 0.7 m−1 to 19.9 ± 1.5 m−1). The FTIR applicator has a wider and shallower heating pattern than the comb slow-wave applicator. Because of the double heating lobes of the FTIR applicator, the effective half temperature heating width is approximately 150 mm. This is wider than the half temperature heating width of the comb slow-wave applicator (95 mm).

Continuous scanning leaky‐wave antenna (LWA) based on second‐mode spoof surface plasmon polaritons (SSPPs) excitation has been proposed and validated in this article. Different from the existing modulation methods, connecting axisymmetric rectangular modulation is adopted to excite the −first harmonic. In this way, the slow‐wave bound on the surface of the transmission line is converted into a radiation wave in space. To the authors' knowledge, this is the first presentation of LWA design utilizing second‐mode SSPPs excitation. In the range from 5.0 to 9.0 GHz, the proposed LWA realizes continuous scanning from −54° ~ 11° with a quasi‐omnidirectional beam in the vertical plane. A prototype of the proposed antenna is fabricated and measured, and the measured results show good agreement with the simulated. The proposed LWA has potential applications in communication systems and radars. [ABSTRACT FROM AUTHOR]

A millimeter‐wave slow‐wave transmission line (T‐line) implemented with Si‐benzocyclobutene (Si‐BCB) technology is modeled in this paper. An artificial neural network (ANN) is applied to map the numerical relationship between the geometric parameters of the slow‐wave T‐line and its S‐parameters. The Levenberg–Marquardt algorithm and Gradient Descent Back‐Propagation optimization method are used during ANN training process. A 30‐GHz coupler based on the proposed slow‐wave structure is fabricated and measured. The ANN results, electromagnetic (EM)‐simulated results, and measured results are consistent with one another. [ABSTRACT FROM AUTHOR]

Background The incidence of dementia has reached epidemic levels, both globally and here in Ireland. Many adults with dementia living in the community remain inactive with some also suffering from sleep disturbances. There is evidence to suggest sufficient exercise and sleep can have a positive influence on cognition also. In this study, we explore: physical activity levels sleep patterns, of community dwelling people with dementia and explore the association they have on: cognitive function quality of life. Methods Each individual was assigned a Withings-Go wrist-watch to wear over a period of 3 months which measured their: daily steps taken time in deep sleep time in light sleep. total sleep each night MMSE and DEM QoL were used to measure cognitive function and quality of life respectively. Assessed at: baseline & after 3 months. This data was coded and analysed using Microsoft Excel and SPSS. Results An RHO = 0.617 was detected between the DEMQoL scores and the mean steps taken over the last 5 days of data collection. An RHO = -0.127 was detected between steps and sleep time which implied that as steps increased, sleep time was reduced with the opposite being applicable also. The average total sleep time for the sample was 08:03:00 (hh:mm:ss) while the average daily steps taken by the group was 3,266 steps. Conclusion People with dementia living in the community were found to be physically inactive. This study has displayed that increased levels of physical activity can show signs of an improved self-perceived quality of life. This study was a correlational study and causality was not investigated. The association we have identified may provide support and foundation for future studies that explore causal components. [ABSTRACT FROM AUTHOR]

In this paper, a miniaturized substrate integrated waveguide (SIW) band-pass cavity filter is presented. Miniaturization is achieved using the half-mode (HM) principle so the lateral dimension of the filter can be reduced by half. Moreover, the slow-wave (SW) technique is used to decrease the center frequency by more than 30 % . Combining these two techniques will reduce filter dimensions by more than 75 % in comparison with the original SIW. By using an electromagnetic (EM) solver the effect of each geometrical parameter on the filter performance is demonstrated. Measurements on the fabricated filter are in good agreement with the numerical results. Input return loss is better than 10 dB, insertion loss of the filter is lower than 2.5 dB across a bandwidth of 3.3 GHz. [ABSTRACT FROM AUTHOR]

This paper presents slow-wave transmission lines based on non-periodic reactive loading. Specifically, the loading elements are stepped impedance shunt stubs (SISS). By sacrificing periodicity using SISS tuned to different frequencies, multiple transmission zeros above the pass band arise, and the rejection level and bandwidth of the stop band is improved as compared with those of periodic structures. Through a proper design, it is possible to achieve compact lines, simultaneously providing the required electrical length and characteristic impedance at the design frequency (dictated by specifications), and efficiently filtering the response at higher frequencies. These lines are applied to the design of a compact power splitter with filtering capability in this work. The length of the splitter, based on a 35.35 Ω impedance inverter, is reduced by a factor of roughly two. Moreover, harmonic suppression better than 20 dB up to the fourth harmonic is achieved. [ABSTRACT FROM AUTHOR]

A compact substrate integrated waveguide (SIW) liquids permittivity sensor structure that utilizes half-mode (HM) and slow-wave (SW) techniques for the miniaturization of SIW sensor is presented in this paper. First, HM miniaturization technique is applied to SIW resonator cavity. Sensor width is reduced by 50% in comparison to the conventional resonator. Due to the complexity of the relationship between the complex permittivity of the substrate and liquids under test, artificial neural network tool is used as a simple and fast method to determine liquids’ complex permittivity through the measured resonant frequency and unloaded quality factor. The sensor is fabricated, and good agreement with simulations is observed according to the obtained experimental results. In the second step, SW and HM techniques are applied to the SIW sensor. The application of the HM and SW techniques indicate that an increase in sensor miniaturization while obtaining a better quality factor could be achieved. Furthermore, HM-SW-SIW is not fabricated, and we are satisfied with simulation results since we have fabricated other components. Moreover, good correspondence between the measurement and simulation results is obtained. Finally, a comparison between the structures presented in this paper and those published previously is made, demonstrating that a minimum of 25% miniaturization is achieved while maintaining acceptable characteristics. [ABSTRACT FROM AUTHOR]

Background: Mild traumatic brain injury (mTBI) is a leading cause of sustained impairments in military service members, Veterans, and civilians. However, few treatments are available for mTBI, partially because the mechanism of persistent mTBI deficits is not fully understood. Methods: We used magnetoencephalography (MEG) to investigate neuronal changes in individuals with mTBI following a passive neurofeedback-based treatment programme called IASIS. This programme involved applying low-intensity pulses using transcranial electrical stimulation (LIP-tES) with electroencephalography monitoring. Study participants included six individuals with mTBI and persistent post-concussive symptoms (PCS). MEG exams were performed at baseline and follow-up to evaluate the effect of IASIS on brain functioning. Results: At the baseline MEG exam, all participants had abnormal slow-waves. In the follow-up MEG exam, the participants showed significantly reduced abnormal slow-waves with an average reduction of 53.6 ± 24.6% in slow-wave total score. The participants also showed significant reduction of PCS scores after IASIS treatment, with an average reduction of 52.76 ± 26.4% in PCS total score. Conclusions: The present study demonstrates, for the first time, the neuroimaging-based documentation of the effect of LIP-tES treatment on brain functioning in mTBI. The mechanisms of LIP-tES treatment are discussed, with an emphasis on LIP-tES’s potentiation of the mTBI healing process. [ABSTRACT FROM PUBLISHER]

Traumatic brain injury (TBI) is a leading cause of sustained impairment in military and civilian populations. However, mild TBI (mTBI) can be difficult to detect using conventional MRI or CT. Injured brain tissues in mTBI patients generate abnormal slow-waves (1–4 Hz) that can be measured and localized by resting-state magnetoencephalography (MEG). In this study, we develop a voxel-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mTBI on a single-subject basis. A normative database of resting-state MEG source magnitude images (1–4 Hz) from 79 healthy control subjects was established for all brain voxels. The high-resolution MEG source magnitude images were obtained by our recent Fast-VESTAL method. In 84 mTBI patients with persistent post-concussive symptoms (36 from blasts, and 48 from non-blast causes), our method detected abnormalities at the positive detection rates of 84.5%, 86.1%, and 83.3% for the combined (blast-induced plus with non-blast causes), blast, and non-blast mTBI groups, respectively. We found that prefrontal, posterior parietal, inferior temporal, hippocampus, and cerebella areas were particularly vulnerable to head trauma. The result also showed that MEG slow-wave generation in prefrontal areas positively correlated with personality change, trouble concentrating, affective lability, and depression symptoms. Discussion is provided regarding the neuronal mechanisms of MEG slow-wave generation due to deafferentation caused by axonal injury and/or blockages/limitations of cholinergic transmission in TBI. This study provides an effective way for using MEG slow-wave source imaging to localize affected areas and supports MEG as a tool for assisting the diagnosis of mTBI.

Background: We used functional connectivity measures from brain resting state functional magnetic resonance imaging to identify human neural correlates of sedation with dexmedetomidine or propofol and their similarities with natural sleep.Methods: Connectivity within the resting state networks that are proposed to sustain consciousness generation was compared between deep non-rapid-eye-movement (N3) sleep, dexmedetomidine sedation, and propofol sedation in volunteers who became unresponsive to verbal command. A newly acquired dexmedetomidine dataset was compared with our previously published propofol and N3 sleep datasets.Results: In all three unresponsive states (dexmedetomidine sedation, propofol sedation, and N3 sleep), within-network functional connectivity, including thalamic functional connectivity in the higher-order (default mode, executive control, and salience) networks, was significantly reduced as compared with the wake state. Thalamic functional connectivity was not reduced for unresponsive states within lower-order (auditory, sensorimotor, and visual) networks. Voxel-wise statistical comparisons between the different unresponsive states revealed that thalamic functional connectivity with the medial prefrontal/anterior cingulate cortex and with the mesopontine area was reduced least during dexmedetomidine-induced unresponsiveness and most during propofol-induced unresponsiveness. The reduction seen during N3 sleep was intermediate between those of dexmedetomidine and propofol.Conclusions: Thalamic connectivity with key nodes of arousal and saliency detection networks was relatively preserved during N3 sleep and dexmedetomidine-induced unresponsiveness as compared to propofol. These network effects may explain the rapid recovery of oriented responsiveness to external stimulation seen under dexmedetomidine sedation.Trial Registry Number: Committee number: 'Comité d'Ethique Hospitalo-Facultaire Universitaire de Liège' (707); EudraCT number: 2012-003562-40; internal reference: 20121/135; accepted on August 31, 2012; Chair: Prof G. Rorive. As it was considered a phase I clinical trial, this protocol does not appear on the EudraCT public website. [ABSTRACT FROM AUTHOR]

Background: Gastrointestinal (GI) motility disorders represent a group of problems that more constantly encountered in preterm infants. However, whether hypoxia exposure contributes to the GI dysfunctions is still unclear.Methods: Newborn mice were exposed to hypoxia (10%) from P1 to P7. Intestinal motilities were examined by a strain gauge transducer. The proliferation of ICCs was detected by using immunostaining for BrdU, Ki67, Kit, Ano1, and insulin-like growth factor 1 receptor (IGF-1R+). Smooth muscle cells and enteric neurons were revealed by immunostaining for α-SMA and NF200, respectively. Apoptosis was assessed by TUNEL assay. Kit signal pathway was examined by western blot and qPCR.Results: Intestinal motilities were found weakened significantly in the hypoxic small intestines as compared to controls on P8. Kit+ or Ano1+ interstitial cells of Cajal (ICCs) were found obviously decreased in the myenteric ICCs (ICC-MY) of neonatal mice after exposed to hypoxia. A large number of ICC progenitors (IGF-1R+) were found highly mitotic (BrdU+ Ki67+) to populate ICC during early postnatal development in the normoxic mice. We found the ICC proliferation was significantly inhibited upon hypoxia exposure, without increasing apoptosis (TUNEL+). We next identified that Kit phosphorylation was inhibited 3 days after hypoxia exposure. The inhibition of Kit signaling was largely due to decreased the expression of the ligand of Kit receptor, stem cell factor (SCF), in the intestinal walls. Exposure to imatinib, a Kit receptor inhibitor, for 3 days from P4 phenocopied the effect of hypoxia on the neonatal pups that resulted in inhibited intestinal motilities and decreased Kit+ ICC numbers.Conclusion: All together, our findings indicate the SCF/Kit signaling insufficiency may contribute to the underdevelopment of ICCs and intestinal motility dysfunction upon hypoxia exposure. The decease in ICC density is likely due to the cell cycle arrest of ICC progenitor cells. [ABSTRACT FROM AUTHOR]

Aim Gastrointestinal motility disorders are presumed to be associated with abnormalities of the generation of slow-wave electric impulses. A requirement for the development of non-invasive clinical methods for the diagnosis of motility disorders is the identification of these signals. We set out to separate and characterize the signals from the various sections of the gastrointestinal tract and to detect changes in the smooth muscle electromyography (SEMG) signals. Methods Partially resected (stomach–small intestine, stomach–large intestine or small and large intestine) or non-resected male SPRD rats were measured under deep anaesthesia. Bipolar thread and disk electrodes and strain gauge sensors were used for SEMG and the detection of mechanical contractions, respectively. The electric activity was characterized by cycle per minute (cpm) and power spectrum density maximum (PsD max ) W by fast Fourier transformation analysis. Contractions were evaluated by area under the curve analysis. Results The myoelectric signals of the stomach, ileum and caecum were at 3–5, 20–25 and 1–3 cpm, respectively. Neostigmine increased (40–60%), while atropine decreased (30–50%) the PsD max values. However, the cpm values remained unchanged. Linear regression revealed a good correlation between the PsD max values and the smooth muscle contractions. Conclusions Electric signals of the same character were recorded from the organ and from the abdominal surface. The change in PsD max perfectly reflects the change in the contractions of the smooth muscle. These results may serve as the basis for non-invasive gastrointestinal measurements in experimental animals, which can be translated into clinical practice for motility studies. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the effects of slow-wave disruption on positive and negative word recognition in a sample of healthy control participants and those with major depressive disorder. Prior to sleep, participants learned a set of emotional and neutral words during an encoding task by responding whether or not the word described them. Following baseline sleep, participants underwent one night of selective slow-wave disruption by auditory stimuli. Accuracy and reaction time to a recognition word set, including both positive and negative words, was assessed in the morning. Repeated-measures ANOVA revealed a significant interaction between word valence and condition, with positive words recognized significantly faster than negative words after disruption, in only healthy control participants. There were no significant results in those with major depressive disorder, or with regard to accuracy. These results may add to the increasing body of literature suggesting a hedonic bias to positive stimuli following sleep disruption. [ABSTRACT FROM AUTHOR]

A 18–24 GHz broadband power amplifier (PA) by 0.18-μm CMOS technology is presented in this article. The low loss microstrip line matching technique is used to reduce transmission losses and achieve higher gain, PAE, and enough output power. An improved gain-boosting technique is also included in the PA architecture to improve high-frequency gain and gain flatness. The measurement results show that small-signal gain is large than 18.5 dB from 18 to 24 GHz, while the gain variation is less than 1.5 dB. The maximum PAE is about 18%, and the outputP1dBis 13.1  and 15 dBmPsat. [ABSTRACT FROM AUTHOR]

In this work, a size-reduced wideband coupler is presented and demonstrated, which explores the slow-wave half-mode substrate integrated waveguide (SW-HMSIW) technique on a printed circuit board process. The SW-HMSIW coupler is composed of two SW-HMSIW transmission lines loaded with a polyline network. Along the coupler, energy is coupled by the electric and magnetic field between the two parallel SW-HMSIW lines. Compared with conventional microstrip coupler, the proposed coupler presents lower loss owning to the HWSIW structure performance. In addition, the proposed SW-HMSIW coupler exhibits a smaller size against its SIW and HWSIW counterparts, thanks to slow-wave effects of the loaded polyline. Measured and simulated results are in a good agreement. [ABSTRACT FROM PUBLISHER]

This article investigates the propagation along coplanar waveguide (CPW) structures, where multiwalled carbon nanotubes (MWCNTs) network layers are deposited using inkjet printing. Electrical parameters are extracted from measured S-parameters data over the frequency range from 10 MHz to 26.5 GHz. The results clearly demonstrate two distinct propagation modes. At low-frequencies, a slow-wave factor up to 7 is achieved. With increasing frequency, attenuation becomes significant, while the propagation constant tends to a linear TEM regime. An equivalent lumped element circuit for CPW structure with MWCNTs network is developed and describes well the measured behavior up to 26.5 GHz. Thanks to the extracted equivalent circuit, the origin of the observed slow-wave phenomenon is confirmed: it is ascribed to a larger capacitance per unit length of the CPW line induced by the presence of the CNTs network that prevents/limits the expansion of fields into air. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1118-1124, 2014 [ABSTRACT FROM AUTHOR]

Abstract: In adult brain tissue, thyroid hormones are known to have multiple effects which are not mediated by chronic influences of the hormones on heterodimeric thyroid hormone nuclear receptors. Previous work has shown that acute microinjections of l-triiodothyronine (T3) to the preoptic region significantly influence EEG-defined sleep in hypothyroid rats. The current study examined the effects of similar microinjections in euthyroid rats. In 7 rats with histologically confirmed microinjection sites bilaterally placed in the preoptic region, slow-wave sleep time was significantly decreased, but REM and waking were increased as compared to vehicle-injected controls. The EEG-defined parameters were significantly influenced by the microinjections in a biphasic dose-response relationship; the lowest (0.3μg) and highest (10μg) doses tested were without significant effect while intermediate doses (1 and 3μg) induced significant differences from controls. There were significant diurnal variations in the measures, yet no significant interactions between the effect of hormone and time of day were demonstrated. Core body temperature was not significantly altered in the current study. The demonstration of effects of T3 within hours instead of days is consistent with a rapid mechanism of action such as a direct influence on neurotransmission. Since the T3-mediated effects were robust in the current work, euthyroid rats retain thyroid hormone sensitivity which would be needed if sleep-regulatory mechanisms in the preoptic region are continuously modulated by the hormones. This article is part of a Special Issue entitled LInked: BRES-D-12-01552 & BRES-D-12-01363R2. [Copyright &y& Elsevier]

This article presents a miniaturized 90° coupler incorporating slotted conductor-backed coplanar waveguide (S-CBCPW) transmission lines (TLs) and four shunt capacitors. The periodically slotted ground achieves higher slow-wave factor (SWF) or effective permittivity (εeff), and lower attenuation constant. Electrical characteristics of the S-CBCPW TLs are investigated by different slotted ground layers. Moreover, trade-offs among SWF, characteristic impedance, and electrical length for the design are also discussed. Finally, the measured 24-GHz coupler not only features smallest normalized chip area among previously reported CMOS couplers but also demonstrates excellent results which are comparable to the designs at 60 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1174-1178, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27525 [ABSTRACT FROM AUTHOR]

Several unit cells of conductor-backed coplanar waveguides with and without loading using thin-film ceramic technology are investigated. The frequency-dependent lumped equivalent circuit values of the cells are extracted from the full-wave electromagnetic analysis. Slow-wave periodic transmission lines and end-coupling bandpass filters (BPFs) are designed, fabricated, and measured. Size reductions of 23% and 27% for the loaded filters and several times increase of inverter values for the coupling inverters are achieved compared to that for the unloaded ones. A systematic design method by using cell cascading with compensation is proposed for the designs of the lines and filters. It is also demonstrated that “finite ground,” used in conductor-backed coplanar waveguides in the literature, is no longer suitable for the end-coupling BPFs due to the leakages. The leakages of finite ground deteriorate the stopband rejection of filters as much as up to 32 dB compared with that of “via ground.” [ABSTRACT FROM PUBLISHER]

A conventional compact microstrip resonant cell (CMRC) has been thoroughly investigated to enhance its slow-wave properties and subsequently ensure an efficient miniaturization of a microstrip circuit.The geometry of a classic CMRC has been improved in terms of slow-wave effect in two progressive steps: (i) a single-element topology has been replaced with a double-element one and (ii) a high-impedance section has been refined by means of an optimized meander line characterized by the minimal number of discontinuities. Vital usefulness of the novel CMRC in the process of microstrip circuit miniaturization has been proven and experimentally validated on the basis of a compact 3-dB branch-line coupler illustrating the possibilities of the approach. A prototype structure has been designed to mimic the performance of a classic coupler, simultaneously presenting a substantial 85% surface area reduction. The measured in-band results are in excellent accordance with theoretical characteristics, whereas the broadband performance depicts an additional phenomenon, that is, the efficient suppression of unwanted signals up to the sixth harmonic. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1949-1954, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26980 [ABSTRACT FROM AUTHOR]

Abstract: Traumatic brain injury (TBI) is a leading cause of sustained impairment in military and civilian populations. However, mild (and some moderate) TBI can be difficult to diagnose because the injuries are often not detectable on conventional MRI or CT. Injured brain tissues in TBI patients generate abnormal low-frequency magnetic activity (ALFMA, peaked at 1–4Hz) that can be measured and localized by magnetoencephalography (MEG). We developed a new automated MEG low-frequency source imaging method and applied this method in 45 mild TBI (23 from combat-related blasts, and 22 from non-blast causes) and 10 moderate TBI patients (non-blast causes). Seventeen of the patients with mild TBI from blasts had tertiary injuries resulting from the blast. The results show our method detected abnormalities at the rates of 87% for the mild TBI group (blast-induced plus non-blast causes) and 100% for the moderate group. Among the mild TBI patients, the rates of abnormalities were 96% and 77% for the blast and non-blast TBI groups, respectively. The spatial characteristics of abnormal slow-wave generation measured by Z scores in the mild blast TBI group significantly correlated with those in non-blast mild TBI group. Among 96 cortical regions, the likelihood of abnormal slow-wave generation was less in the mild TBI patients with blast than in the mild non-blast TBI patients, suggesting possible protective effects due to the military helmet and armor. Finally, the number of cortical regions that generated abnormal slow-waves correlated significantly with the total post-concussive symptom scores in TBI patients. This study provides a foundation for using MEG low-frequency source imaging to support the clinical diagnosis of TBI. [Copyright &y& Elsevier]

Abstract: This paper presents an improved active transmitting antenna. Defected ground structures (DGSs) are used to eliminate the higher mode radiation. Slow-wave propagation is realized by adopting DGS and photonic band-gap (PBG) structure, and consequently, size reduction is achieved. Suppression of the excited surface-waves of the patch antenna is realized by using an array of rectangular PBGs. Higher mode reduction is realized by using DGS. Measurement results are presented and discussed. [Copyright &y& Elsevier]

Abstract: We propose a slow-wave MEMS phase shifter that can be fabricated using the CMOS back-end and an additional maskless post-process etch. The tunable phase shifter concept is formed by a conventional slow-wave transmission line. The metallic ribbons that form the patterned floating shield of this type of structure are released to allow motion when a control voltage is applied, which changes the characteristic impedance and the phase velocity. For this device a quality factor greater than 40 can be maintained, resulting in a figure of merit on the order of 0.7dB/360° and a total area smaller than 0.14mm2 for a 60-GHz working frequency. [Copyright &y& Elsevier]

This work is a study of the dielectric propagation properties of laminar substrates, which are known to support low dispersion modes with very small phase velocities. Slow modes are linked to a polarization mode supported by the insulator-semiconductor interface. The mode spectrum of metal-insulator-semiconductor lines is controlled by the substrate resistivity and the ratio of the semiconductor to insulator layer thicknesses. An experimental investigation of substrate modes normally requires the laborious fabrication of many specimens to cover a useful range of parameter variation. In this paper, we present an experimental platform that supports slow-wave propagation and allows easy adjustment of the parameters affecting the interfacacial polarization mechanism. [ABSTRACT FROM AUTHOR]

Abstract: The propagation characteristics of metal–insulator–semiconductor (MIS) lines are controlled by the resistivity of the substrate, the operating frequency and the ratio of the semiconductor to insulator layer thicknesses. A strong interfacial polarisation, also known as the Maxwell–Wagner polarisation, is often responsible for the significant slow-down of the propagation velocity of MIS microstrip transmission lines. This phenomenon has been applied in the development of miniature delay lines exhibiting large electrical dimensions. In this paper we review most previously presented designs and we examine the effect of this polarization mechanism under various parameters. Finally, the presented micro-scale delay lines, exhibit comparable slowing factors with our predecessors at the cost of lower attenuation. [Copyright &y& Elsevier]

A conventional rat-race coupler has been doubly miniaturized: (i) characteristic impedances and electrical lengths of microstrip sections have been adequately modified as the first step of size reduction and (ii) T-shaped PBG cells have been implemented to diminish strip section length as the second step of circuit miniaturization. The experimental results show good agreement with theoretical characteristics. Furthermore, the proposed seven-section PBG coupler enabled the achievement of 85% scale of size reduction in the final design, which proves the attractiveness of presented miniaturization method. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2910–2913, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24789 [ABSTRACT FROM AUTHOR]

Two broadband compact doubly perforated hybrid couplers have been designed, manufactured, and measured. To improve frequency characteristics and to reduce circuit dimensions, two kinds of perforations have been introduced: the defected ground structures in the ground plane metallization and photonic bandgap cells in the strip metallization. Measurement results show essential miniaturization (∼39% and ∼36%) and enhancement of the bandwidth (∼47% and ∼75 %). © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2149–2152, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24566 [ABSTRACT FROM AUTHOR]

Time delay lines based on periodic microstrip lines (PMLs) and composite right/left-handed transmission lines (CRLH-TLs) are proposed. Compared with ordinary microstrip lines, PMLs are more suitable to realize tiny time delays because of their slow-wave characteristics. Meanwhile, CRLH-TLs are chosen to realize large time delays due to their large and easy designable phase constant. Finally, a 9-bit time delay module is designed and fabricated as an example. It is shown that the present time delay module possesses the advantages of compactness, low-loss, precise, and easy fabrication. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1679–1682, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24409 [ABSTRACT FROM AUTHOR]

Abstract: This study investigated preparatory processes involved in adapting to changing episodic memory retrieval demands. Event-related potentials (ERPs) were recorded while participants performed a general old/new recognition task and a specific task that also required retrieval of perceptual details. The relevant task remained either constant or changed (predictably or randomly) across trials. Responses were slowed when participants switched from the specific to the general task but not vice versa. Hence, asymmetrical switch costs were observed, suggesting that retrieval preparation is dependent not only on the current retrieval goal but also influenced by recent retrieval attempts. Consistently, over posterior scalp regions ERPs associated with advance preparation were modulated by the preceding task, reflecting increased attentional selection requirements for the general task, and by the foreknowledge about the task sequence. When retrieval demands remained constant, frontal slow-waves elicited by retrieval-cues were more positive going for the specific task, indicating full implementation of a retrieval orientation that allows more efficient retrieval of perceptual details. [Copyright &y& Elsevier]

This article presents a planar branch-line hybrid coupler with an effective technique for harmonic suppression and size reduction. The proposed technique served by a microstrip electromagnetic bandgap element entitled MEBE (compact microstrip resonant cell) is used to suppress the harmonics and reduce the length of a quarter wavelength line when compared with the conventional branch-line coupler. The planar structure enables an easy circuit implementation in printed circuit boards without any additional process and lumped elements. From the measured results, better than 30 dB suppression for the second harmonic and 18 dB suppression for the third harmonic are obtained while maintaining the characteristics of conventional branch-line hybrid coupler. It is able to achieve two insertion losses of less than 3.5 dB, the return loss of 18 dB, and isolation of 19 dB at operating frequency. With our improved beeline compact microstrip resonant cell, compact branch-line coupler occupying areas of 35.86% relative to conventional designs has been realized. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1080–1084, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24241 [ABSTRACT FROM AUTHOR]

Microwave soil heating deactivates weed seeds; however, in many modern agricultural settings, weed seeds are mostly found in the top 1–2 cm of the soil profile. Until recently, microwave soil heating has been achieved using various antennas, which project the microwave energy deeply into the soil. The aim of this research was to develop new microwave applicators that provide shallow heating (less than 50 mm). This paper presents two applicator designs, one based on a comb slow-wave structure and the other on the frustrated total internal reflection (FTIR) principle, which utilise evanescent microwave fields to restrict the depth of microwave heating. The background theory to their performance is presented, followed by experimental evidence of their constrained heating performance under different soil moisture scenarios. Experimental measurements of the heating performance of these applicators, in soils of varying moisture content, demonstrate that the evanescent microwave fields restrict the depth of heating, so that most of the energy is manifested in the top 50 mm of soil. The evanescent field decay rate for the FTIR applicator changes from 44.0 ± 0.7 m−1 to 30 ± 1.2 m−1 as the soil moisture changes from 32% to 174% (dry weight basis). This is higher than the evanescent field decay rate for the comb slow-wave applicator (17.6 ± 0.7 m−1 to 19.9 ± 1.5 m−1). The FTIR applicator has a wider and shallower heating pattern than the comb slow-wave applicator. Because of the double heating lobes of the FTIR applicator, the effective half temperature heating width is approximately 150 mm. This is wider than the half temperature heating width of the comb slow-wave applicator (95 mm). [ABSTRACT FROM AUTHOR]

In this paper, a new microstrip stepped-impedance hairpin resonator with interdigital capacitor (IDC) slow-wave band-pass filter (BPF) using dielectric supported air-gapped microstrip line (DAML) of surface micromachining on GaAs substrate is proposed. Unlike conventional slow-wave filters, the proposed bandpass filters are designed to produce a narrow passband at the fundamental mode of the resonators with small size and a sharp skirt characteristic. The proposed slow-wave band-pass filter with IDC is designed to produce a passband of 7.7% at the fundamental frequency of 56 GHz. It shows insertion loss of 3.37 dB, return loss of better than 15 dB, and a stopband characteristic greater than 31 dB within 37.03–45.51 GHz. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1244–1247, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21667 [ABSTRACT FROM AUTHOR]