Investigation of Magnetoelectric Sensor Requirements for Deep Brain Stimulation Electrode Localization and Rotational Orientation Detection

Correct position and orientation of a directional deep brain stimulation (DBS) electrode in the patient’s brain must be known to fully exploit its benefit in guiding stimulation programming. Magnetoelectric (ME) sensors can play a critical role here. The aim of this study was to determine the minimum required limit of detection (LOD) of a ME sensor that can be used for this application by measuring the magnetic field induced by DBS. For this experiment, a commercial DBS system was integrated into a head phantom and placed inside of a state-of-the-art Superconducting Quantum Interference Device (SQUID)-based magnetoencephalography system. Measurements were performed and analyzed with digital signal processing. Investigations have shown that the minimum required detection limit depends on various factors such as: measurement distance to electrode, bandwidth of magnetic sensor, stimulation amplitude, stimulation pulse width, and measurement duration. For a sensor that detects only a single DBS frequency (stimulation frequency or its harmonics), a LOD of at least 0.04 pT/Hz0.5 is required for 3 mA stimulation amplitude and 60 μμs pulse width. This LOD value increases by an order of magnitude to 0.4 pT/Hz0.5 for a 1 kHz, and by approximately two orders to 3 pT/Hz0.5 for a 10 kHz sensor bandwidth. By averaging, the LOD can be reduced by at least another 2 orders of magnitude with a measurement duration of a few minutes.

Cavity buildup dispersion spectroscopy

Measurements of ultrahigh-fidelity absorption spectra can help validate quantum theory, engineer ultracold chemistry, and remotely sense atmospheres. Recent achievements in cavity-enhanced spectroscopy using either frequency-based dispersion or time-based absorption approaches have set new records for accuracy with uncertainties at the sub-per-mil level. However, laser scanning or susceptibility to nonlinearities limits their ultimate performance. Here we present cavity buildup dispersion spectroscopy (CBDS), probing the CO molecule as an example, in which the dispersive frequency shift of a cavity resonance is encoded in the cavity’s transient response to a phase-locked non-resonant laser excitation. Beating between optical frequencies during buildup exactly localizes detuning from mode center, and thus enables single-shot dispersion measurements. CBDS can yield an accuracy limited by the chosen frequency standard and measurement duration and is currently 50 times less susceptible to detection nonlinearity compared to intensity-based methods. Moreover, CBDS is significantly faster than previous frequency-based cavity-enhanced methods. The generality of CBDS shows promise for improving fundamental research into a variety of light–matter interactions.

Comparing the usefulness of a new algorithm to measure visual field using the variational Bayes linear regression in glaucoma patients, in comparison to the Swedish interactive thresholding algorithm

Background/aimsWe previously reported that the visual field (VF) prediction model using the variational Bayes linear regression (VBLR) is useful for accurately predicting VF progression in glaucoma (Invest Ophthalmol Vis Sci. 2014, 2018). We constructed a VF measurement algorithm using VBLR, and the purpose of this study was to investigate its usefulness.Method122 eyes of 73 patients with open-angle glaucoma were included in the current study. VF measurement was performed using the currently proposed VBLR programme with AP-7700 perimetry (KOWA). VF measurements were also conducted using the Swedish interactive thresholding algorithm (SITA) standard programme with Humphrey field analyser. VF measurements were performed using the 24–2 test grid. Visual sensitivities, test–retest reproducibility and measurement duration were compared between the two algorithms.ResultMean mean deviation (MD) values with SITA standard were −7.9 and −8.7 dB (first and second measurements), whereas those with VBLR-VF were −8.2 and −8.0 dB, respectively. There were no significant differences across these values. The correlation coefficient of MD values between the 2 algorithms was 0.97 or 0.98. Test–retest reproducibility did not differ between the two algorithms. Mean measurement duration with SITA standard was 6 min and 02 s or 6 min and 00 s (first or second measurement), whereas a significantly shorter duration was associated with VBLR-VF (5 min and 23 s or 5 min and 30 s).ConclusionVBLR-VF reduced test duration while maintaining the same accuracy as the SITA-standard.

Survey on Measurement Methods for IPv6 Deployment

Nowadays we use Internet Protocol (IP) versions 4 (IPv4) and 6 (IPv6) at the same time. It is very difficult to determine the rate of IPv6 and the state of its deployment exactly. In our survey, paper we present some tools and methods that can be used to estimate the proportion of IPv6. First, we will show some server side methods that mostly use provider-measurable data, so they may not be available to everyone. Next, we introduce various client-side tools that can be used in a much broader context, and then present the use of survey methods. Then we are reviewing some researches, which provide more comprehensive insight into the transition to IPv6 using complex measurement methods. Finally, we compare and categorize the presented metrics based on the availability of data sources and the extent of the measurement duration. We know that there is clearly no best among the various methods. Choosing the right technique depends greatly on the data and tools available to the researcher.

Radar-Based Detection of Respiration Rate with Adaptive Harmonic Quefrency Selection

Continuous respiration monitoring is important for predicting a potential disease. Due to respiration measurements using contact sensors, it is difficult to achieve continuous measurement because the sensors are inconvenient to attach. In this study, a radar sensor was used for non-contact respiration measurements. The radar sensor had a high precision and could even be used in the dark. It could also be used continuously regardless of time and place. The radar sensor relied on the periodicity of respiration to detect the respiration rate. A respiration adaptive interval was set and the respiration rate was detected through harmonic quefrency selection. As a result, it was confirmed that there was no difference between the respiratory rate measured using a respiration belt and the respiratory rate detected using a radar sensor. Furthermore, case studies on changes in the radar position and about measurement for long periods confirmed that the radar sensor could detect respiration rate continuously regardless of the position and measurement duration.

A Low-Cost and Customizable TEER Meter for the Measurements of Cellular Barrier Integrity

<p>A low-cost and translational TEER (trans-endothelial/epithelial electric resistance) meter was designed, fabricated, validated, and applied in this paper. TEER is a critical tool to quantitate the integrity of biological barriers. Commercially available TEER meters are expensive (thousands of dollars) with low customization capability. Using Arduino, an open-source hardware and program that are used to control electronics, we fabricated the TEER meter that costs ~$50 to purchase the parts and 2 hours to be constructed. Robust characterization and validation shows that the meter can accurately measure TEER values between 132 and 82,500 Ω·cm² with <3% errors, which covers the reported TEER ranges based on a literature study we conducted. The temporal resolution, the measurement duration, and the electrode configurations of meter are also customizable. We successfully applied the meter to measure TEERs of endothelial cell monolayers, finding that cells treated with histamine have lower TEER values compared to untreated cells (793.4 ± 190.5 Ω·cm²vs. 3027.5 ± 664.4 Ω∙cm²; p < 0.001), which is consistent with literature results. We further validated the TEER measurement by showing that histamine increased the intercellular gap from 2.34 ± 0.12 µm to 5.49 ± 0.17 µm, causing leakier endothelial barriers and thus lower TEERs. In conclusion, we report for the first time a low-cost Arduino-based TEER meter capable of accurately measuring TEERs in the relevant range. We also include detailed tutorials in the supplementary information to promote the translation of the technology. </p>

A Low-Cost and Customizable TEER Meter for the Measurements of Cellular Barrier Integrity

<p>A low-cost and translational TEER (trans-endothelial/epithelial electric resistance) meter was designed, fabricated, validated, and applied in this paper. TEER is a critical tool to quantitate the integrity of biological barriers. Commercially available TEER meters are expensive (thousands of dollars) with low customization capability. Using Arduino, an open-source hardware and program that are used to control electronics, we fabricated the TEER meter that costs ~$50 to purchase the parts and 2 hours to be constructed. Robust characterization and validation shows that the meter can accurately measure TEER values between 132 and 82,500 Ω·cm² with <3% errors, which covers the reported TEER ranges based on a literature study we conducted. The temporal resolution, the measurement duration, and the electrode configurations of meter are also customizable. We successfully applied the meter to measure TEERs of endothelial cell monolayers, finding that cells treated with histamine have lower TEER values compared to untreated cells (793.4 ± 190.5 Ω·cm²vs. 3027.5 ± 664.4 Ω∙cm²; p < 0.001), which is consistent with literature results. We further validated the TEER measurement by showing that histamine increased the intercellular gap from 2.34 ± 0.12 µm to 5.49 ± 0.17 µm, causing leakier endothelial barriers and thus lower TEERs. In conclusion, we report for the first time a low-cost Arduino-based TEER meter capable of accurately measuring TEERs in the relevant range. We also include detailed tutorials in the supplementary information to promote the translation of the technology. </p>