Response Measurements Research Articles

Electroencephalographic power ratio and peak frequency difference associate with central sensitization in chronic pain.

Central sensitization, or increased responsiveness of the central nervous system to sensory input, is present in many chronic pain patients. Clinically, it is detected through subjective, patient-reported measures. There is a need for reliable, direct measurements of neural response to controlled stimuli to quantify neuronal dysfunction in pain. The goal of this work is to investigate cortical activity, recorded via electroencephalogram (EEG), during objective and calibrated painful stimulation in chronic pain patients.&#xD;Approach. Chronic pain patients (N=8) and healthy controls (N=8) participated in this study. We recorded electroencephalography (EEG) at rest (baseline) and during evoked pain tasks, including thermal and mechanical stimuli. The evoked pain was applied following the quantitative sensory testing (QST) protocol, which is a research technique that applies objective, calibrated painful stimuli. &#xD;Main results. Peak alpha frequency at rest was significantly lower in chronic pain patients compared to healthy controls (p<0.0002), while EEG alpha/theta and alpha/beta power ratios at rest were higher in patients (p<0.0002). During thermal QST, these power ratios decreased in patients and increased in controls (p<0.0002 for both). During mechanical QST, power ratios decreased or did not change. Furthermore, the peak theta-beta frequency difference at baseline was significantly lower in patients compared to controls (p<0.0002). During thermal QST, this difference increased in patients and decreased in controls; during mechanical QST, this difference increased in both patients and controls (p<0.0002). Functional connectivity analysis showed that controls had greater baseline theta connectivity strength that increased during mechanical QST (p<0.0002).&#xD;Significance. This work demonstrates differential patterns of EEG activity at rest and during acute painful stimulation in chronic pain patients compared to healthy controls. These measures may quantify an individual's tendency to experience chronic pain and central sensitization and serve as diagnostic biomarkers.

High cell throughput, programmable fixation reveals the RNA and protein co-regulation with spatially resolved NFκB pseudo-signaling.

RNA translation to protein is paramount to creating life, yet RNA and protein correlations vary widely across tissues, cells, and species. To investigate these perplexing results, we utilize a time-series fixation method that combines static stimulation and a programmable formaldehyde perfusion to map pseudo-Signaling with Omics signatures (pSigOmics) of single-cell data from hundreds of thousands of cells. Using the widely studied nuclear factor kappa B (NFκB) mammalian signaling pathway in mouse fibroblasts, we discovered a novel asynchronous pseudotime regulation (APR) between RNA and protein levels in the quintessential NFκB p65 protein using single molecule spatial imaging. Prototypical NFκB dynamics are successfully confirmed by the rise and fall of NFκB response as well as A20 negative inhibitor activity by 90 min. The observed p65 translational APR is evident in both statically sampled timepoints and dynamic response gradients from programmable formaldehyde fixation, which successfully creates continuous response measurements. Finally, we implement a graph neural network model capable of predicting APR cell subpopulations from GAPDH RNA spatial expression, which is strongly correlated with p65 RNA signatures. Successful decision tree classifiers on Potential of Heat-diffusion for Affinity-based Trajectory Embedding embeddings of our data, which illustrate partitions of APR cell subpopulations in latent space, further confirm the APR patterns. Together, our data suggest an RNA-protein regulatory framework in which translation adapts to signaling events and illuminates how immune signaling is timed across various cell subpopulations.

Computed Tomography Scan and Clinical-based Complete Response Prediction in Locally Advanced Rectal Cancer after Neoadjuvant Chemoradiotherapy: A Machine Learning Approach

Abstract Background: Treatment of locally advanced rectal cancer (LARC) involves neoadjuvant chemoradiotherapy (nCRT), followed by total mesorectal excision. Examining the response to treatment is one of the most important factors in the follow-up of patients; therefore, in this study, radiomics patterns derived from pretreatment computed tomography images in rectal cancer and its relationship with treatment response measurement criteria have been investigated. Methods: Fifty patients with rectal adenocarcinoma who were candidates for nCRT and surgery were included. The information obtained from the tumor surgical pathology report, including pathological T and N, the degree of tumor differentiation, lymphovascular invasion, and perineural invasion along with radiomics characteristics to each patient, was assessed. Modeling with disturbed forest model was used for radiomics data. For other variables, Shapiro–Wilk, Chi-Square, and Pearson Chi-square tests were used. Results: The participants of this study were 50 patients (23 males [46%] and 27 females [54%]). There was no significant difference in the rate of response to neoadjuvant treatment in between age and gender groups. According to the modeling based on combined clinical and radiomics data together, area under the curves for the nonresponders and complete respond group (responder group) was 0.97 and 0.99, respectively. Conclusion: Random forests modeling based on combined radiomics and clinical characteristics of the pretreatment tumor images has the ability to predict the response or non-response to neoadjuvant treatment in LARC to an acceptable extent.

Automated ultrasonographic pupillary assessment: a new neuro-ophthalmological assessment tool.

To evaluate correlations between ultrasonographic pupillary assessment (UPA) and automated UPA in neurocritical patients. This was a prospective, observational study of 20 adult patients admitted to the intensive care unit with neurological pathology. Between UPA and automated UPA, 40 pupillary measurements were made. The time required to conduct UPA and automated UPA on a single patient was consistently < 3 minutes. Automated UPA required a markedly shorter operational time than UPA. There were strong positive associations between UPA and automated UPA measurements, with the following correlations: right eye at rest, r = 0.9973; left eye at rest, r = 0.9989; right eye post-pupillary light response, r = 0.9975; left eye post-pupillary light response, r = 0.9955. Bland-Altman analyses confirmed the strong agreement between the two methods under both conditions, with most measurements falling within the limits of agreement. Both the right and left pupillary diameters at rest demonstrated consistency, and the post-pupillary light response measurements for both eyes indicated good agreement, with a few outliers. Automated UPA was strongly correlated with UPA in neurocritical patients. Automated UPA is a rapid, feasible, and noninvasive method that enables the precise evaluation of pupillary size and light response.

Dietary supplementation with thyme oil improves the reproductive characteristics of Barki adult and prepubertal ewes

The reproductive technology has a significant impact on the development of livestock production. The thyme oil, rich in phytoestrogen chemicals like apigenin, has been found to enhance reproductive performance by mimicking estrogen’s action. This study aimed to investigate the effects of oral supplementation with thyme essential oil on the reproductive organ biometry, and reproductive performance in adult and prepubertal Barki ewes. Seventy ewes were treated with intravaginal sponges impregnated with 40 mg. medroxyprogesterone acetate for 14 days and simultaneously assigned randomly to two groups (20 adult and 15 prepubertal ewes per group), i.e., a control and a thyme oil treated (2.25 mg/kg body weight) group. The number of follicles, follicle diameter, corpora lutea diameter, and estrogen concentration were higher in the thyme oil-treated group than in the control group without comparing between adult ewes and prepubertal ewes. Additionally, the number and diameter of the large follicles were higher (P < 0.05) in the right-side ovary of adult ewes compared with that in prepubertal ewes at day 15. Moreover, thyme oil treatment resulted in higher conception (P < 0.01), lambing rates (P < 0.05), and fecundity (P < 0.01), with values 95.12, 136.73, and 130.25 compared with those in the control group, with values 63.51, 105.24, and 66.97, respectively, without comparing between adult ewes and prepubertal ewes. The adult ewes had a stronger estrus response and better fertility measurement values than prepubertal ewes. Additionally, the estrogen serum levels were positively correlated with the number (P < 0.05) and diameter (P < 0.01) of follicles, and the progesterone serum concentration was positively correlated with the corpora lutea diameter (P < 0.01), without treated group. In conclusion, dietary supplementation with thyme oil improved the follicular population and reproductive performance, which has a good effect on the adult and prepubertal ewes in the Barki ewes.

Influence of high-k La2O3 interfacial oxide layer on the performance of GaN based Schottky barrier ultraviolet-B and A photodetection sensors

GaN based metal-semiconductor-metal (MSM) type Schottky heterojunction-based ultraviolet (UV) photodetectors (PDs) have already proven as an efficient candidate for photodetection applications. However, in real time applications, GaN based MSM type UV PD device display higher dark current, weak signal detection and required external bias are seriously limiting their usage. Therefore, self-powered interdigitated electrode type Cr/Cu/La2O3/GaN: MIS (metal-insulator-semiconductor) heterojunction visible blind UV PD has been fabricated and studied in UV-B and A region. The structure, morphology, chemical and optical parameters of La2O3 films were evaluated using GIXRD, AFM, XPS and UV–Vis techniques, respectively. The reported interdigitated Cr/Cu/La2O3/GaN: MIS UV PD device yielded a higher Schottky barrier height (SBH) of 0.95 eV (dark) and 0.89 eV (360 nm) indicating the formation of higher potential barrier. At an applied bias of 0 V, the fabricated GaN MIS PD yielded an UV to visible rejection ratio (R360/R400) of 1.62 × 102. In UV-A region (at 0 V of 360 nm), the fabricated Cr/Cu/La2O3/GaN: MIS UV PD device exhibited a peak responsivity of 28.9 mAW−1, D∗ of 3.57 × 1012 Jones and EQE of 19.2 %. On the other hand, in UV-B region (at 0 V of 310 nm) the MIS UV PD device exhibited a peak responsivity of 34.4 mAW−1, D∗ of 4.2 × 1012 Jones and EQE of 22.7 %. During 360 nm illumination (at 0 V), the temporal response measurements of GaN UV PD device yielded the best rise/fall times of 70 ms/141 ms. This work validates the fact that the high-k La2O3 thin film as an interfacial oxide layer at the metal/GaN interface provides a novel solution for the photo detection field in the self-powered mode i.e., without any external bias.

Reflected encounters at hunter-gatherer rock art sites by the water

ABSTRACT This article seeks to recapture the sensory experiences of prehistoric hunter-gatherers in the Finnish Lake District by examining the acoustics of their rock art sites. The sites consist of vertical cliffs rising directly from the lakes, with painted images of humans, boats, and animals, sometimes also drummers (5000–1500 calBC). The acoustic impulse response measurements performed at 37 sites indicate that the painted cliffs, in their original state, reflected sound more strongly and accurately than the nearby lakeshore rocks. The psychoacoustic criterion and the auralizations created through artistic improvisations indicate that the reflections generated discrete single-repeat echoes, which endowed sounds produced in front of the cliffs with their auditory mirror images. As these reflections appeared to emanate from invisible sources behind the paintings, the auditory and visual images overlapped merging into one multisensory experience. Although the sounds and music of prehistoric people are beyond our reach, the study shows that the physical environment actively participated in their activities, co-vibrating and creating reciprocal tangible encounters between the human and more-than-human worlds. For the history of sound and music, the study provides an example of how significant a role sound reflections could have in past societies.

Calibration of pressures measured via tubing systems: Accounting for laboratory environmental variations between tubing response measurement and wind tunnel testing

Accurate pressure measurements on structures via tubing systems during wind tunnel tests are crucial for precise estimation of wind loads. While calibration studies have traditionally focused on the contribution of tubing configuration to pressure distortion, they often overlook the effects of environmental parameter changes between the measurement of tubing response and aerodynamic pressure on structures. However, higher atmospheric pressure and lower ambient temperature can substantially increase tubing response distortion. To address this, this study introduces a dynamic calibration approach that accounts for such laboratory environmental changes. This method integrates the experimental transfer function, obtained under specific environmental conditions, with numerical estimates of the impact of environmental changes, to derive transfer functions for the desired environmental conditions. The effectiveness of this approach was validated using experimental and numerical transfer functions under two distinct environmental conditions. A case study for outdoor open-circuit laboratories revealed that neglecting environmental conditions during dynamic pressure calibrations could lead to overall average deviations in peak pressures across the channels on a building face of up to ≈ 5%, with local maximum deviations reaching ≈ 10%, respectively. Therefore, the proposed calibration method can significantly enhance the accuracy of pressure measurements via tubing systems, particularly when the tubing response and the pressures are measured under different environmental conditions.

Dynamic response and tension estimation of stay cables with disturbed images acquired from vision sensors

ABSTRACT This study introduces a novel approach to measure cable responses of such bridges using a vision sensor comprising a digital camcorder mounted on a tripod. Prioritizing simplicity and efficiency, this setup requires minimal equipment. The sensor is strategically positioned to ensure the target cable remains within the camcorder’s field of view. However, operational bridge imagery is frequently disturbed by vehicular traffic, leading to defocusing and blurring due to the camcorder’s automatic focus adjustments. These disturbances complicate the identification of reference points essential for accurate cable response measurements, potentially skewing results. To address this, we apply an image quality evaluation method to distinguish reference points from disturbed images, mitigating the impact of these disturbances on measurement accuracy. We evaluated the method’s effectiveness in estimating cable tension under disturbances by capturing images of an operational cable-stayed bridge experiencing ambient vibrations. Cable tension estimations were derived from the analysed responses using the vibration method and validated against data from a long-term monitoring accelerometer. This comparison highlights the potential of the proposed vision sensor method to enhance the accuracy of cable tension measurements in cable-stayed bridges, even in the presence of disturbed images.

Guidance to investigate university students’ bodily responses and perceptual assessments in sound exposure experiments

Previous studies have shown that sound influences students both physiologically and perceptually. However, most of these studies focussed on the effects of sounds at group-level, ignoring individual differences. Therefore, we investigated which indicators can be used to identify differences in bodily responses and perceptual assessments of each individual when exposed to four different sounds. First, based on an audiometric test, the hearing acuity of 15 students (from five different profiles based on their acoustical preferences and needs) was measured. Then, two sound exposure experiments were conducted in the SenseLab: direct sound exposure using earbuds in a laboratory setting, and indirect sound exposure with speakers in a real room setting. During each experiment, the attention level (AL), mental relaxation level (MRL), heart rate (HR), and respiration rate (RR) were measured with wearable devices, and students made perceptual assessments of each condition. The percentage of change normalised the four bodily response measurements among students. Based on correlation analysis and t-tests, bodily responses, and perceptual assessments across experiments were compared, at group-level and individual-level. Six students, who suffered from mild hearing loss in low-frequency sounds, showed bodily responses such as increased HR during exposure to low-frequency sound conditions. Perceptual assessments of different sound types during both lab experiments substantiated the acoustical preferences of the students from the five profiles. Bodily responses showed no strong nor significant correlations with perceptual assessments during the direct sound exposure experiments. Differences in bodily responses and perceptual assessments between the two experiments and between group-level and individual-level were observed in AL. It is concluded that hearing acuity and type of sound (sound frequencies) are key indicators for identifying differences in bodily responses (such as HR and RR) and perceptual assessment. For future research, it is crucial to consider incorporating audiometric tests, bodily responses such as HR and RR, and perceptual assessments in this type of investigations.

Site response measurements and implications for soil deformation using geophysical and geotechnical characterization of Djen-Djen Port, Jijel, Northeast Algeria

This paper describes the concept used to develop a methodology and an integrated approach based on the ambient vibration horizontal-to-vertical spectral ratio (HVSR) combined with geotechnical analysis for assessing soil deformations observed in Djen-Djen port located near Jijel-City (north-east Algeria).140 ambient vibrations recording were carried out to generate a spatial distribution map of the HVSR curves, seismic vulnerability index (Kg) and the ground shear strain GSS-(γ) value distribution maps. The spatial distribution of Kg and GSS-(γ) values estimated correlates well with both the geological units and soil deformations in the study area. In addition, the mapping of the spatial distribution of the HVSR curves delineates six distinct zones, thus reflecting the sensitivity of the HVSR peak amplification factor with the compactness and technical properties of the soil.The qualitative and quantitative analysis developed in this study made it possible to characterize the embankments, settlement, and liquefaction observed at the port of Djen-Djen in eastern Algeria. This paper shows that the HVSR method is a useful and promising technique for studying soil settlement and liquefaction. The Kg and GSS maps can be used as a guide to implementation of geotechnical tests before any conventional study and as well to identify sites that are vulnerable to deformation for seismic hazard reduction.

Semicircular canal drug delivery safely targets the inner ear perilymphatic space.

Effective, reproducible, and safe delivery of therapeutics into the inner ear is required for the prevention and treatment of hearing loss. A commonly used delivery method is via the posterior semicircular canal (PSCC); however, its specific targeting within the cochlea remains unclear, impacting precision and reproducibility. To assess safety and target specificity, we conducted in vivo recordings of the pharmacological manipulations delivered through the PSCC. Measurements of auditory brainstem response (ABR), vibrometry, and vestibular behavioral and sensory-evoked potential (VsEP) revealed preserved hearing and vestibular functions after artificial perilymph injections. Injection of curare, a mechanoelectrical transducer (MET) channel blocker that affects hearing when in the endolymph, had no effect on ABR or VsEP thresholds. Conversely, injection of CNQX, an AMPA receptor blocker, or lidocaine, a Na+ channel blocker, which affects hearing when in the perilymph, significantly increased both thresholds, indicating that PSCC injections selectively target the perilymphatic space. In vivo tracking of gold nanoparticles confirmed their exclusive distribution in the perilymph during PSCC injection, supporting the pharmacological finding. Together, PSCC injection is a safe method for inner ear delivery, specifically targeting the perilymphatic space. Our findings will allow for precise delivery of therapeutics within the inner ear for therapeutic and research purposes.

Computer-Vision-Aided Deflection Influences Line Identification of Concrete Bridge Enhanced by Edge Detection and Time-Domain Forward Inference

To enhance the accuracy and efficiency of the deflection response measurement of concrete bridges with a non-contact scheme and address the ill-conditioned nature of the inverse problem in influence line (IL) identification, this study introduces a computer-vision-aided deflection IL identification method that integrates edge detection and time-domain forward inference (TDFI). The methodology proposed in this research leverages computer vision technology with edge detection to surpass traditional contact-based measurement methods, greatly enhancing the operational efficiency and applicability of IL identification and, in particular, addressing the challenge of accurately measuring small deflections in concrete bridges. To mitigate the limitations of the Lucas–Kanade (LK) optical flow method, such as unclear feature points within the camera’s field of view and occasional point loss in certain video frames, an edge detection technique is employed to identify maximum values in the first-order derivatives of the image, creating virtual tracking points at the bridge edges through image processing. By precisely defining the bridge boundaries, only the essential structural attributes are preserved to enhance the reliability of minimal deflection deformations under vehicular loads. To tackle the ill-posed nature of the inverse problem, a TDFI model is introduced to identify IL, recursively capturing the static bridge response generated by the bridge under the influence of successive axles of a multi-axle vehicle. The IL is then computed by dividing the response by the weight of the preceding axle. Furthermore, an axle weight ratio reduction coefficient is proposed to mitigate noise amplification issues, ensuring that the weight of the preceding axle surpasses that of any other axle. To validate the accuracy and robustness of the proposed method, it is applied to numerical examples of a simply supported concrete beam, indoor experiments on a similar beam, and field tests on a three-span continuous concrete beam bridge.

Influence of Strain Rate and Temperature on the Multiaxial Failure Stress Locus of a Polyamide Syntactic Foam

This study introduces a comprehensive experimental methodology allowing for the direct measurement of the rate dependent multiaxial response of polymer syntactic foams under combined direct-shear loading. The combined tension-torsion behaviour of a syntactic foam and its rate dependence are investigated for the first time.Dynamic tension-torsion experiments were conducted using a newly developed Tension-Torsion Hopkinson Bar (TTHB) enabling the measurement of the combined tensile-shear response of engineering materials at high rates of strain.The response and multiaxial failure envelope of a polyamide syntactic foam were experimentally measured and analysed to determine the combined influences of stress state, strain rate, and temperature. The multiaxial failure stress locus was defined in both the normal versus shear stress space and the principal stress space, providing a comprehensive characterisation of the behaviour of the material under various loading and environmental conditions.The suitability of existing pressure dependent failure criteria to represent the measured experimental data was also assessed. The Drucker-Prager pressure dependent criterion proved to be effective in capturing the measured quasi-static and dynamic multi-axial stress loci at different temperatures.The effects of temperature, loading rate and stress state on the deformation and failure modes were analysed by means of SEM micrographs of the tested samples.

Target-free vision method for planar displacement measurement of structures subjected to out-of-plane movement by UAV

In the field of structural health monitoring, one of the essential tasks is to measure dynamic responses such as vibration displacement. With the recent advancement in computer vision, cameras are developed as alternative tools to traditional displacement sensors. Unmanned aerial vehicles (UAVs) offer mobility and can handle complex real-world situations. However, limitations of using UAVs, particularly self-motions, have hindered the accuracy in vibration displacement measurements. This paper proposes a target-free vision-based approach for measuring dynamic displacement responses using UAV. A series of videos of a beam subjected to planar motions are captured using a UAV. Stationary features on the background and target features on the structure are detected using features from accelerated segment test with adaptive threshold strategy and tracked using the Kanade–Lucas–Tomasi. UAV self-motions are estimated using motion-only bundle adjustment. Dynamic displacement responses of the structure are computed based on the displacements of target features and UAV self-motions. Results of the displacement responses and identified natural frequencies with different planar motion types and shooting angles are obtained. They are compared with those obtained by linear variable differential transducers, which demonstrates the accuracy of the proposed method for vibration displacement response measurement.

Performance optimization of AlN ultrasonic thin-film sensors deposited by RF magnetron sputtering

The AlN thin-film ultrasonic transducers were deposited by reactive RF magnetron sputtering technique. The effects of deposition parameters: target-substrate distance, argon-nitrogen flow ratio, deposition time, substrate temperature and radial distance from the deposition center on the ultrasonic performance of AlN thin films were studied. A metal electrode layer was deposited on the AlN film transducer to fabricate an ultrasonic temperature sensor, and the effects of the size and thickness of the electrode layer on the performance of the sensor were studied. Piezoelectric response measurements were performed in air over a temperature range of −60 °C–900 °C, and the dependence of ultrasonic response (time-of-flight and pulse echo amplitude) on temperature was analyzed. Long-term heat treatment in air at 750 °C for 128 h showed that the high-entropy alloy oxide protective layer could effectively delay oxidation of the AlN layer and improve the service life of the sensor.

Dynamic Response of a Rotor Supported on Hybrid Bearings in Air, Water, and Liquid Nitrogen: Measurements and Comparisons to Predictions

Abstract Modern liquid rocket engine turbopumps implement hybrid bearings, which combine hydrostatic and hydrodynamic fluid film principles, in compact and lightweight units known for their superior reusability, durability, and reliability. This study aims to provide extensive and reliable test data for the purpose of anchoring and benchmarking predictive tools for these bearings. This paper provides comprehensive dynamic response measurements of a rotor weighing 10.40 kg and approximately 60 mm in diameter at the bearing locations. The test rotor is supported on two hybrid journal bearings with a bearing length to bearing diameter ratio of approximately 0.42 and a bearing radial clearance to rotor radius ratio of around 0.0017. The bearings are tested with air, water, and liquid nitrogen, serving as surrogate test fluids for common propellants in liquid rocket engines. Rotor run-up and speed coast-down tests are conducted to measure shaft motion responses. The results clearly demonstrate that the rotordynamic characteristics of the test rotor supported on the hybrid journal bearings largely rely on properties of the test fluids and their feeding conditions. Notably, when air is pressurized into the test bearings, the shaft motion responses differ markedly from those observed with water and liquid nitrogen, primarily due to significantly lower stiffness and damping coefficients. Furthermore, rotor speed coast-down tests for each test fluid exhibit notable differences in coast-down speed over time characteristics, depending on the test fluid properties. The predicted rotor imbalance responses exhibit excellent correlation with the measurement data. The steady increase of demand and growth of the fluid film bearing technology for reusable rocket engines require accurate bearing design tools, the extensive component testing, and the implementation of the technology. The validated and developed bearing predictive models from previous research demonstrate well the characteristics of bearings under various operating fluids conditions. The findings and database presented in this work contribute not only to comprehending the performance of hybrid bearings but also to understanding and enhancing the dynamic characteristics of rotor systems supported on hybrid bearings.

Compressed sensing with smooth L0 constraints for moving force identification from bridge response measurements

Abstract Compressed sensing (CS), as an emerging information sampling technique, has been successfully applied in the field of moving force identification (MFI). However, existing MFI CS models often fail to obtain the optimal sparse solutions and frequently underestimate the amplitude of local impact forces. To effectively address this issue, a new CS method is proposed for MFI based on smooth L0 norm constraints and bridge response measurements. Firstly, a smooth function is used to approximate the L0 norm, establishing a noise CS reconstruction model for MFI. The introduction of the smoothing function can locally convexify the original MFI problem and enhance the smoothness and differentiability of the objective function, making the optimization problem easier to solve. Subsequently, the Polak–Ribiere–Polyak formula is adopted to point the descent direction of the new objective function, and the sparse solution is iteratively advanced through the conjugate gradient algorithm. Finally, the applicability and feasibility of the proposed method is confirmed by numerical simulations and vehicle–bridge interaction tests, respectively. The results show that the proposed method can accurately identify moving forces from limited measurements of bridge responses. Compared with existing methods, it can provide more precise sparse solutions with higher robustness to measurement noises, and address the issue of underestimating on the amplitude of local impact forces, which is expected to enhance the performance and in-situ applicability of MFI.

Greater humoral EBV response may be associated with choroid plexus inflammation in progressive MS.

Choroid plexus (CP) inflammation can be quantified in vivo with MRI in people with multiple sclerosis (pwMS). It remains unknown whether Epstein Barr Virus (EBV) is related to CP changes. Total of 170 pwMS (116 relapsing-remitting; RRMS and 54 progressive MS; PMS) underwent MRI examination and measurement of humoral anti-EBV response. CP volume and CP pseudo-T2 (pT2), a relaxation time indicative of edema and neuroinflammation, were measured. Moreover, anti-EBV nuclear antigen-1 (EBNA-1) IgG and anti-EBV capsid antigen (VCA) IgG antibodies were measured. The PMS group had greater CP pT2 value when compared to RRMS (1120ms vs. 954ms, p = 0.037). After adjusting for age and therapy effects, higher CP pT2 values were associated with higher anti-EBNA-1 IgG levels only in PMS (r = 0.352, p = 0.015). Higher Anti-EBV humoral response in pwMS may be associated with increased CP neuroinflammatory changes and may be more relevant for the later chronic stage of the disease. Large-scale studies should investigate whether these findings are generalizable to all types of progressive MS.

Wideband microwave frequency response measurement based on optical phase-locked loop.

Frequency response measurement, or the forward transmission coefficient (S21) measurement for a two-port network, is the key function of a vector network analyzer (VNA). In this paper, a broadband and high dynamic range (DR) microwave S21 parameter measurement scheme based on an optical phase-locked loop (OPLL) is proposed. By heterodyning two phase-locked hybrid integrated ultra-narrow linewidth lasers, a microwave signal with low phase noise and spurious level is generated as the incident signal and reference signal, and the signal frequency can be easily manipulated over a wide range by tuning the master laser wavelength. In the receiver, the radio frequency (RF) signals are down-converted to intermediate frequency (IF) signals with the phase-locked lasers. By sampling and processing the IF signals the S21 parameter of the DUT can be acquired. A proof-of-concept experiment is performed, and with available photodetectors, phase modulators and phase-locked loops, a measurable range of 2 to 18 GHz is achieved. The demonstrated minimum frequency resolution of the OPLL-based RF signal synthesizer is 10 Hz. The system DR exceeds 68 dB at an equivalent resolution bandwidth of 1 kHz. The S21 parameters of a power divider and a bandpass filter are measured, and the results are well consistent with those of a commercial VNA. The DR and measurable range limit factors and possible extension methods are discussed. The proposed approach offers a high potential way to develop a wideband, high DR, and fully integrated VNA.