Significant Changes In Amplitude Research Articles

Effect of alternate nostril breathing on evoked potentials among internet addicts.

Increased availability of smartphones and easy access to the internet among adolescents has resulted in Internet Addiction (IA). Effects of IA and Pranayama on evoked potential are available but studies on the comparison of immediate and 6-week effects of alternate nostril breathing on evoked potentials among medicos with internet addiction are not available as per our search in PubMed, hence the study was chosen. In this comparative study 100 male and female medical students aged between 18-25 years, with internet addiction scores ≥ 50 were included as study participants. P300 auditory event-related potential and pattern reversal visual evoked potential (VEP) were recorded before, immediately, and 6 weeks after practicing pranayama. Repeated measure ANOVA shows statistically significant change (P<0.05) in P300 amplitude, P100 latency, N145 latency, and VEP amplitude. The post hoc Bonferroni test shows that P100 latency and N145 latency significantly reduced immediately after 15 minutes of pranayama. P300 amplitude and VEP amplitude significantly increased only after practicing pranayama for 6 weeks. Pranayama has an immediate effect on latency, but it takes 6 weeks of practice to significantly change amplitude.

3 Tesla magnetic resonance imaging in patients with cardiac implantable electronic devices: a single centre experience.

Three Tesla (T) magnetic resonance imaging (MRI) provides critical imaging information for many conditions. Owing to potential interactions of the magnetic field, it is largely withheld from patients with cardiac implantable electronic devices (CIEDs). Therefore, we assessed the safety of 3T MRI in patients with '3T MRI-conditional' and 'non-3T MRI-conditional' CIEDs. We performed a retrospective single-centre analysis of clinically indicated 3T MRI examinations in patients with conventional pacemakers, cardiac resynchronization devices, and implanted defibrillators from April 2020 to May 2022. All CIEDs were interrogated and programmed before and after scanning. Adverse events included all-cause death, arrhythmias, loss of capture, inappropriate anti-tachycardia therapies, electrical reset, and lead or generator failure during or shortly after MRI. Changes in signal amplitude and lead impedance were systematically assessed. Statistics included median and interquartile range. A total of 132 MRI examinations were performed on a 3T scanner in 97 patients. Thirty-five examinations were performed in patients with 'non-3T MRI-conditional' CIEDs. Twenty-six scans were performed in pacemaker-dependent patients. No adverse events occurred during or shortly after MRI. P-wave or R-wave reductions ≥ 50 and ≥ 25%, respectively, were noted after three (2.3%) scans, all in patients with '3T MRI-conditional' CIEDs. Pacing and shock impedance changed by ± 30% in one case (0.7%). Battery voltage and stimulation thresholds did not relevantly change after MRI. Pending verification in independent series, our data suggest that clinically indicated MRI scans at 3T field strength should not be withheld from patients with cardiac pacemakers or defibrillators.

Multifunctional terahertz microscopy for biochemical and chemical imaging and sensing

Laser-excited terahertz emission microscopy (LTEM) has exhibited great potential for studying the dynamic physical properties of various materials and device evaluation. In this study, an up-to-date version of LTEM, the terahertz chemical microscopy, was developed for biochemical and chemical imaging and sensing. By functionalizing a terahertz semiconductor emitter with an ion-sensitive membrane, a DNA aptamer, and a specific polymer, the change in the terahertz signal amplitude attributed to the surface electrical potential change was successfully detected. Accordingly, the measurement of calcium ions (Ca2+), stress biomarker cortisol, and 2, 4, 6-trinitrotoluene (TNT) explosive was achieved. Measured of charged Ca2+ was via the change in the electrical potential of the ion-sensitive membrane with ion accumulation. For non-charged cortisol and TNT measurements, the surface potential change was recorded by the conformational change of the negatively charged DNA aptamer bound to cortisol and the charge-transfer complex formation between TNT and polyethylenimine polymer, respectively. Moreover, the specificity of this sensing approach was demonstrated by molecular docking and measuring the interfering substances such as sodium ions, potassium ions, brain chemicals histamine and dopamine, and TNT analogues. The results showed that the developed multifunctional terahertz microscopy technique can be used for trace biochemical and chemical sensing via visualization of the terahertz amplitude distribution.

Correlation analysis of human upper arm parameters to oscillometric signal in automatic blood pressure measurement

Cardiovascular diseases are the leading cause of global deaths, making cardiovascular health monitoring important. Measuring blood pressure using an automatic sphygmomanometer is the most widely used method to monitor cardiovascular health due to its accessibility, convenience, and strong correlation with cardiovascular diseases. In this work, in order to estimate brachial artery diameter, stiffness, or thickness using an automatic sphygmomanometer, the correlation between upper arm parameters and the oscillometric signal was intensively investigated through analytical, numerical, and experimental approaches. The parametric studies commonly revealed that the inner radius of the brachial artery is the most influential parameter in determining the amplitude of the oscillometric signal. The experimental results of using a cardiovascular simulator (a virtual patient) combined with upper arm phantoms with various inner radii of the brachial artery showed a 6.5% change in the oscillometric signal amplitude with a 10% artery radius variation. It was concluded that the oscillometric signal can be used to evaluate brachial artery diameter. Based on the clinical relationship between brachial artery diameter and cardiovascular risk factors such as hypertension, diabetes, and obesity, this study showed and verified a novel method to monitor brachial artery diameter and hence, cardiovascular risks while measuring blood pressure.

Absence of Neuroplastic Changes in the Bilateral H-Reflex Amplitude following Spinal Manipulation with Activator IV.

Background and Objectives: Chiropractic spinal manipulation is an alternative medical procedure for treating various spinal dysfunctions. Great interest exists in investigating its neuroplastic effects on the central nervous system. Previous studies have found contradictory results in relation to the neuroplastic changes in the H-reflex amplitude as a response to manual spinal manipulation. The discrepancies could be partly due to differences in the unilateral nature of these recordings and/or the variable force exerted in manual techniques applied by distinct chiropractors. Concerning the latter point, the variability in the performance of manual interventions may bias the determination of the significance of changes in H-reflex responses derived from spinal manipulation. To investigate such responses, a chiropractic device can be used to provide more precise and reproducible results. The current contribution aimed to examine whether spinal manipulation with an Activator IV instrument generates neuroplastic effects on the bilateral H-reflex amplitude in dancers and non-dancers. Materials and Methods: A radiograph verified spinal dysfunction in both groups of participants. Since there were significant differences between groups in the mean Hmax values of the H-reflex amplitude before spinal intervention, an assessment was made of the possible dependence of the effects of spinal manipulation with Activator IV on the basal conditions. Results: Ten sessions of spinal manipulation with Activator IV did not cause statistically significant changes in the bilateral H-reflex amplitude (measured as the Hmax/Mmax ratio) in either group. Furthermore, no significant difference was detected in the effects of spinal manipulation between groups, despite their distinct basal H-reflex amplitude. Conclusions: Regarding the therapeutic benefits of a chiropractic adjustment, herein carried out with Activator IV, the present findings suggest that the mechanism of action is not on the monosynaptic H-reflex pathway. Further research is needed to understand the mechanisms involved.

Transcranial Magnetic Stimulation Following a Paired Associative Stimulation Protocol Based on a Video Game Neuromodulates Cortical Excitability and Motor Behavior.

Transcranial Magnetic Stimulation (TMS) can be used to modulate cortico-spinal excitability following a paired associative stimulation (PAS) protocol. Movement-related cortical stimulation (MRCS) is a PAS protocol based on the synchronization of a single-pulse TMS with a movement task. However, plasticity and motor performance potentiation due to MRCS has been related exclusively to single-movement tasks. In order to unveil the effects of an MRCS protocol in complex movements, we applied PAS synchronized with a movement-related dynamic task (MRDT) with a customized video game. In 22 healthy subjects, we measured the reaction time (RT), trajectory error (TE), and the number of collected and avoided items when playing the custom video game to evaluate the task motor performance. Moreover, we assessed the recruitment curve of Motor Evoked Potentials (MEPs) with five different intensities to evaluate the motor corticospinal excitability. MEPs were recorded in Abductor Pollicis Brevis (APB) and Abductor Digiti Minimi (ADM), before, right after, and 30 min after the PAS intervention, in an active versus sham experimental design. The MRCS PAS intervention resulted in RT reduction, and motor corticospinal excitability was modulated, reflected as significant MEP amplitude change at 110% RMT intensity in ADM and at 130% RMT intensity in APB. RTs and ADM MEP amplitudes correlated positively in specific time and intensity assessments. We conclude that the proposed PAS protocol facilitated RT performance in a complex task. This phenomenon might be useful to develop neurorehabilitation strategies with complex movements, similar to activities of daily living.

Correcting the light extinction effect of fly ash particles on the measurement of NO by TDLAS

The measurement of nitric oxide (NO) concentration in power plant flue gas by tunable diode laser absorption spectroscopy (TDLAS) is susceptible to fly ash particles. The presence of fly ash particles causes laser intensity fluctuations and leads to the second harmonic (2f) signal amplitude changes. In this manuscript, we analyzed the influence of particles on the 2f signal and corrected the measurement error of NO concentration by the wavelength modulation-second harmonic (WMS-2f) technique. Specifically, the 2f signal error caused by quartz sand and fly ash particles were measured, and the exponential function representing the peak-to-peak error of the 2f signal was obtained by fitting. Finally, the peak-to-peak value of the 2f signal and the NO concentration were corrected according to the exponential function. After correction, the NO concentration error under the fly ash influence (the particle size in the range of 10–200 μm and the mass concentration is less than 18.26 g/m3) was no more than 2%. This correction method effectively improves the measurement accuracy of NO concentration by the WMS-2f technique in the fly ash environment.

Offset Compensation in Resistive Stretch Sensors Using Low-Frequency Feedback Topology

Respiration monitoring systems play an important role in healthcare and fitness. For this purpose, resistive stretch sensors are frequently used, which are cheap and simple in operation. However, they are not free from drawbacks. Varying offset due to patient movement, low signal amplitude, as well as susceptibility to interference, can all pose serious challenges. In this paper, a novel signal conditioning circuit for a resistive respiration sensor is proposed that alleviates some of the above problems. Namely, the proposed low-frequency feedback topology improves the dynamic range by offset compensation, sustaining a high signal amplification. Further advantages of the new configuration are the phase shift of 0.5 degrees in the band of interest and higher gain for the respiration signal than for the offset. The topology was proved to correctly represent signal amplitude changes, as well as to be able to sample human respiration in the home environment. However, the circuit shows some nonlinear behavior around resistance discontinuity points–settling time after body position change of the patient, which can be as long as 40 s. The circuit was tested both in bench tests and in the prototype of a respiratory polygraphy device during actual sleep apnea examinations. The results indicate that resistive stretch sensors, along with low-frequency feedback topology, are a promising development path for future respiration monitoring devices.

A model-driven approach to ultrasonic detection of state of charge in lithium-ion batteries

Ultrasonic inspection is one non-destructive method to monitor the internal state of lithium-ion battery (LIB) cells. During charging, lithium ions intercalate into the graphite anode, causing moderate volumetric expansion (approximately 10%) and as much as a three-fold increase in Young’s modulus of the anode. Many researchers have observed changes in the time-of-flight (TOF) of through-thickness ultrasonic waves that correlate with changes in the state of charge (SOC). We introduce a transfer matrix method and Bloch-wave formalism for periodically layered media to show that the observed changes in TOF are partially due to the associated changes in anode stiffness. However, more detailed models that consider battery heterogeneity in structure and properties are needed to predict changes in TOF and signal amplitude (SA) for sophisticated ultrasonic measurement configurations and different cell chemistries. We therefore employ a quasi-static homogenization scheme for layered media to estimate the effective anisotropic stiffness of LIB pouch cells as a function of SOC as an input to a time-domain finite element model to determine the influence of changes in the anode, cathode, and separator on the direction-dependent propagation modes. This model is then employed to interpret experimentally obtained TOF and SA data for more robust SOC detection.

Control of Brushless Direct-Current Motors Using Bioelectric EMG Signals.

(1) Background: The purpose of this study was to evaluate the analysis of measurements of bioelectric signals obtained from electromyographic sensors. A system that controls the speed and direction of rotation of a brushless DC motor (BLDC) was developed; (2) Methods: The system was designed and constructed for the acquisition and processing of differential muscle signals. Basic information for the development of the EMG signal processing system was also provided. A controller system implementing the algorithm necessary to control the speed and direction of rotation of the drive rotor was proposed; (3) Results: Using two muscle groups (biceps brachii and triceps), it was possible to control the direction and speed of rotation of the drive unit. The control system changed the rotational speed of the brushless motor with a delay of about 0.5 s in relation to the registered EMG signal amplitude change; (4) Conclusions: The prepared system meets all the design assumptions. In addition, it is scalable and allows users to adjust the signal level. Our designed system can be implemented for rehabilitation, and in exoskeletons or prostheses.

Variabilities in Urban Ambient Noise Before, During, and After Covid-19 Lockdown in the Peruvian Capital

ABSTRACT. Recent studies have shown that urban ambient noise (UAN) decreased at many sites due to a slowdown in human activities brought by the SARS-CoV-2 (COVID-19) pandemic lockdowns. Such understanding is inferred from the historical record of the noise levels, which may also help us disambiguate noise sources as required for ambient noise tomography, microseismic and other seismic based studies. As UAN is site-specific, and its analysis enables passive situational awareness, therefore, in the present study, we analyzed the temporal variations in UAN before, during and after the social isolation in the metropolitan region of Lima, the capital of Peru, for the very first time. We used continuous waveforms recorded from February 1st to August 31st, 2020, at the Ñaña (NNA) broadband seismic station for the analysis. Results show the temporal changes occur in different frequency ranges; for example, at frequencies &gt;1 Hz, significant changes in the mean daytime amplitudes are observed, which are absent in the lower frequency range (0.1–1, 1–3, 3–5 Hz). A maximum noise reduction of 37% is observed and should be considered for any future application of UAN. The results were verified by comparing with Community Mobility Reports (CMR) provided by Google using statistical change-point analysis.

Changes in Corticospinal Excitability and Motor Control During Cerebellar Transcranial Direct Current Stimulation in Healthy Individuals.

Cerebellar transcranial direct current stimulation (ctDCS) modulates the primary motor cortex (M1) via cerebellar brain inhibition (CBI), which affects motor control in humans. However, the effects of ctDCS on motor control are inconsistent because of an incomplete understanding of the real-time changes in the M1 excitability that occur during ctDCS, which determines motor output under regulation by the cerebellum. This study investigated changes in corticospinal excitability and motor control during ctDCS in healthy individuals. In total, 37 healthy individuals participated in three separate experiments. ctDCS (2mA) was applied to the cerebellar hemisphere during the rest condition or a pinch force-tracking task. Motor-evoked potential (MEP) amplitude and the F-wave were assessed before, during, and after ctDCS, and pinch force control was assessed before and during ctDCS. The MEP amplitudes were significantly decreased during anodal ctDCS from 13min after the onset of stimulation, whereas the F-wave was not changed. No significant changes in MEP amplitudes were observed during cathodal and sham ctDCS conditions. The MEP amplitudes were decreased during anodal ctDCS when combined with the pinch force-tracking task, and pinch force control was impaired during anodal ctDCS relative to sham ctDCS. The MEP amplitudes were not significantly changed before and after all ctDCS conditions. Motor cortical excitability was suppressed during anodal ctDCS, and motor control was unskilled during anodal ctDCS when combined with a motor task in healthy individuals. Our findings provided a basic understanding of the clinical application of ctDCS to neurorehabilitation.

From null to midline: changes in head posture do not predictably change head tremor in cervical dystonia.

A common view is that head tremor (HT) in cervical dystonia (CD) decreases when the head assumes an unopposed dystonic posture and increases when the head is held at midline. However, this has not been examined with objective measures in a large, multicenter cohort. For 80 participants with CD and HT, we analyzed videos from examination segments in which participants were instructed to 1) let their head drift to its most comfortable position (null point) and then 2) hold their head straight at midline. We used our previously developed Computational Motor Objective Rater (CMOR) to quantify changes in severity, amplitude, and frequency between the two postures. Although up to 9% of participants had exacerbated HT in midline, across the whole cohort, paired t-tests reveal no significant changes in overall severity (t = -0.23, p = 0.81), amplitude (t = -0.80, p = 0.43), and frequency (t = 1.48, p = 0.14) between the two postures. When instructed to first let their head drift to its null point and then to hold their head straight at midline, most patient's changes in HT were below the thresholds one would expect from the sensitivity of clinical rating scales. Counter to common clinical impression, CMOR objectively showed that HT does not consistently increase at midline posture in comparison to the null posture.

Urban Rail Transit Network Planning Based on Particle Swarm Optimization Algorithm

In order to solve the problem that the urban rail transit network is affected by a large number of signals, resulting in poor control effect, and improve the living comfort of residents near urban rail transit, a study on urban rail transit network planning based on particle swarm optimization algorithm is proposed. The learning factor is dynamically adjusted according to the inertia weight parameters, and the particle swarm optimization parameters are selected in combination with the setting of the maximum velocity parameters. The individual optimal particle is selected by using the dominant relationship between the individual particles, and the optimization of the optimal particle is completed by combining the selection requirements of the global optimal particle. We design the v2x communication implementation scheme, obtain the traffic flow information of urban rail transit, build the signal input and output model based on particle swarm optimization algorithm, obtain the output feedback signal, and determine the planning scale of urban rail transit network, so as to build the urban rail transit network planning model and complete the urban rail transit network planning. The experimental results show that the proposed method can improve the utilization rate of urban rail transit network planning, effectively control the change of network signal amplitude, and reduce the repetition rate of urban rail transit network planning.

Children with strabismus and amblyopia presented abnormal spontaneous brain activities measured through fractional amplitude of low-frequency fluctuation (fALFF).

PurposeBased on fMRI technology, we explored whether children with strabismus and amblyopia (SA) showed significant change in fractional amplitude of low-frequency fluctuation (fALFF) values in specific brain regions compared with healthy controls and whether this change could point to the clinical manifestations and pathogenesis of children with strabismus to a certain extent.MethodsWe enrolled 23 children with SA and the same number matched healthy controls in the ophthalmology department of the First Affiliated Hospital of Nanchang University, and the whole brain was scanned by rs-fMRI. The fALFF value of each brain area was derived to examine whether there is a statistical difference between the two groups. Meanwhile, the ROC curve was made in a view to evaluate whether this difference proves useful as a diagnostic index. Finally, we analyzed whether changes in the fALFF value of some specific brain regions are related to clinical manifestations.ResultsCompared with HCs, children with SA presented decreased fALFF values in the left temporal pole: the superior temporal gyrus, right middle temporal gyrus, right superior frontal gyrus, and right supplementary motor area. Meanwhile, they also showed higher fALFF values in specific brain areas, which included the left precentral gyrus, left inferior parietal, and left precuneus.ConclusionChildren with SA showed abnormal fALFF values in different brain regions. Most of these regions were allocated to the visual formation pathway, the eye movement-related pathway, or other visual-related pathways, suggesting the pathological mechanism of the patient.

Imbibition Retention in the Process of Fluid Replacement in Tight Sandstone Reservoir

“Fracture network stimulation and oil-water infiltration and replacement” are recent attempts to effectively produce oil from tight reservoirs. On the one hand, the formation can be fractured by the fracturing fluid, which can carry proppant into fractures. On the other hand, the fracturing fluid can spontaneously infiltrate into the pores under the action of capillary pressure to displace the oil phase, thereby enhancing the oil recovery. To distinguish imbibition and displacement processes during fluid replacement in tight reservoirs is difficult, and the effect of these two processes is also vaguely defined. In this study, an experimental method that can visualize the imbibition and displacement process is proposed by combining the core slice displacement experiment. Based on this method, the process of imbibition and displacement can be effectively distinguished, and imbibition retention rate can be quantitatively characterized. The effectiveness of this method is proved by taking the core of Chang 7 tight sandstone reservoir in the Ordos Basin as the research object. The results show that the force direction of the fluid under imbibition is related to the wettability, and it is always from the wetting phase to the nonwetting phase, while the force direction of fluid under displacement is mainly related to the directivity of displacement pressure difference. Based on the difference of force action, imbibition and displacement can be quantitatively characterized, respectively. During the imbibition process, the peak value of the NMR curve corresponding to the small pore throat shifts to the left, and the signal amplitude increases. During the displacement process, the peak value of the NMR curve corresponding to the small pore throat has no obvious shift, nor signal amplitude change, but the peak value of the curve corresponding to the large pore throat shifts to the right. The results also indicate that there is an exponential negative correlation between imbibition retention rate and gas permeability. The greater the gas permeability is, the smaller the imbibition retention rate is.

POD analysis of the wake dynamics of an offshore floating wind turbine model

The wake dynamics of a floating wind turbine model experiencing realistic surge motion and immersed within a properly scaled atmospheric boundary layer is studied through wind tunnel experiments. The turbine is modelled by a porous disk representing the floating 2MW wind turbine located at the offshore test site in Le Croisic (France). Experiments were conducted in the LHEEA’s atmospheric wind tunnel. A surge motion is imposed on the model, using a linear actuator, to replicate realistic behaviors under wave swell. Realistic frequencies of actuation are considered to study their effects on the wake properties. The wake is characterized using Stereoscopic Particle Image Velocimetry (SPIV) measurements in a y - z plane normal to the flow, at two different streamwise locations x = 4.6D and 8.1D. In addition to the documentation of the main wake statistics, the velocity fields are analyzed using Proper Orthogonal Decomposition (POD). The velocity field is decomposed into a set of spatial and temporal modes. The eigenvalues convergence is shown to be relatively slow, due to the high Reynolds number turbulent boundary layer within which the model is immersed. When varying the surge motion frequency, the spatial modes do not show any significant change in shape and amplitude. However, the spectral analysis performed on the temporal modes shows the emergence of peaks at the surge motion frequency and the overall increase of the low-frequency energy content in the Power Spectral Density, in particular for the highest frequencies of motion tested.

Spectral Analysis of Resting Near‐Infrared Spectroscopy Shows Preserved Endothelial Function after Aerobic Training Exercise in Chronic Kidney Disease

This study aims to evaluate the effectiveness of aerobic exercise training on microcirculatory function among individuals with chronic kidney disease (CKD). Microcirculatory dysfunction is a prevalent complication in CKD that progresses as CKD evolves. Endothelial dysfunction is an early manifestation of microvascular disease and contributes to increased cardiovascular‐related mortality in CKD. Evidence indicates that endothelial dysfunction might be linked to deficits in blood perfusion and oxygen delivery. Aerobic exercise has been shown to improve cardiorespiratory function and blood pressure control for adults with CKD. Previous work has validated correspondence of specific frequency intervals in resting microvascular blood flow fluctuations with physiological events. Specifically, the spectrum amplitude from three frequency intervals (0.0095 – 0.02 Hz, 0.02 – 0.06 Hz, 0.06 – 0.15 Hz) have been attributed to microvascular regulation by endothelial, neurogenic, and myogenic origins, respectively. We hypothesized that 12 weeks of aerobic exercise would improve endothelial function in CKD.Ten CKD participants (Table 1) were randomized into treatment and control groups that performed progressive aerobic cycling exercise (N = 5) for 20‐45 min up to 80% of heart rate reserve and non‐aerobic, stretching exercise (N = 5). Each group performed activities 3 days/week for 12 weeks. Resting microvascular blood flow was measured in the forearm for 5 minutes using total hemoglobin (tHb) signal from near‐infrared spectroscopy. Reactive hyperemic index (RHI) was measured using peripheral artery tonometry at the upper arm, providing an accepted, single‐value index of endothelial function. Both measures were obtained at the beginning (baseline) and end of the 12‐week intervention (EOS), respectively. The resting tHb signal was analyzed using wavelet transform to obtain time‐frequency information on microcirculation regulated by endothelial, neurogenic, and myogenic functions. Differences at baseline and EOS were assessed using pairwise Student’s t‐test (statistical significance: p &lt; 0.05). The Pearson correlation coefficient between RHI and individual mean spectral amplitude was also obtained.Endothelial spectral amplitudes significantly decreased (p = 0.007) in the stretching group over the 12‐week intervention, suggesting decreased endothelial function (Fig.1). There was no significant change in the endothelial spectral amplitude (p = 0.16) in the cycling group. Changes in individual endothelial spectral amplitude and RHI were moderately correlated (r = 0.57 and p = 0.02).In conclusion, spectral analysis of resting microvascular blood flow in CKD suggests preserved endothelial function over 12 weeks of progressive aerobic cycling exercise, compared with a decline in those who performed a non‐aerobic stretching exercise. Ongoing work focuses on adapting and applying this wavelet methodology to MRI‐derived signals that provide temporo‐spatially resolved information on tissue oxygenation and perfusion. Resting microcirculatory properties yielded from this work may be useful for monitoring disease progression and guiding targeted therapeutic strategies to improve microvascular function in CKD.

TRANSCORNEAL ELECTRICAL STIMULATION THERAPY MAY HAVE A STABILIZATION EFFECT ON MULTIFOCAL ELECTRORETINOGRAPHY FOR PATIENTS WITH RETINITIS PIGMENTOSA.

To assess the effects of transcorneal electrical stimulation (TES) on several measures of visual function in retinitis pigmentosa. This prospective, randomized, fellow-eye-controlled study includes 30 eyes of 15 patients with retinitis pigmentosa. Each patient's eyes were randomly selected as treatment (TE) and control eye (CE), and 30 minutes/week TES was applied for 6 months. Patient evaluations were performed before and after TES, including comprehensive ophthalmological examination, visual fields, full-field and multifocal electroretinography, microperimetry, and optical coherence tomography. All parameters were compared before and after TES and between TE and CE. After TES, the mean signal amplitudes in multifocal electroretinography were stabilized in TE. The mean signal amplitudes in CE decreased in every ring, reaching significance in the fifth ring (847.15 ± 393.94 and 678.77 ± 282.66 nV, P = 0.039, before and after TES, respectively). The changes in the mean signal amplitudes of TE and CE were -0.38 ± 295.53 and -185.15 ± 332,62 nV in second (P = 0.046), 36.69 ± 326.4 and -143.38 ± 317,41 nV in fourth (P = 0.028), and -17.46 ± 333.07 and -168.38 ± 297,14 nV in fifth rings (P = 0.046), respectively. The decrease in the mean signal amplitudes between 2° and 20° midperipheral retina was significantly less in TE (-33.59 ± 225,1 nV) than CE (-205.56 ± 345.1 nV) (P = 0.011). There were no significant changes in other parameters. The progression in multifocal electroretinography might be stabilized with TES. Further studies with larger sample sizes and a longer follow-up are needed to conclude that TES reduces retinitis pigmentosa progression.

On the characterization of tidal ocean-dynamo signals in coastal magnetic observatories

Periodic tidal ocean currents induce electric currents and, therefore, magnetic field signals that are observable using spaceborne and ground-based observation techniques. In theory, the signals can be used to monitor oceanic temperature and salinity variations. Tidal magnetic field amplitudes and phases have been extracted from magnetometer measurements in the past. However, due to uncertainties caused by a plentitude of influencing factors, the shape and temporal variation of these signals are only known to a limited extent. This study uses past extraction methods to characterize seasonal variations and long-term trends in the ten year magnetometer time series of three coastal island observatories. First, we assess data processing procedures used to prepare ground-based magnetometer observations for tidal ocean dynamo signal extraction to demonstrate that existing approaches, i.e., subtraction of core field models or first-order differencing, are unable to reliably remove low-frequency contributions. We hence propose low-frequency filtering using smoothing splines and demonstrate the advantages over the existing approaches. Second, we determine signal and side peak magnitudes of the M2 tide induced magnetic field signal by spectral analysis of the processed data. We find evidence for seasonal magnetic field signal variations of up to 25% from the annual mean. Third, to characterize the long-term behavior of tidal ocean dynamo signal amplitudes and phases, we apply different signal extraction techniques to identify tidal ocean-dynamo signal amplitudes and phases in sub-series of the ten-year time series with incrementally increasing lengths. The analyses support three main findings: (1) trends cause signal amplitude changes of up to approx 1~nT and phase changes are in the order of {mathcal {O}}(10^{circ }) within the observation period; (2) at least four years of data are needed to obtain reliable amplitude and phase values with the extraction methods used and (3) signal phases are a less dependent on the chosen extraction method than signal amplitudes.Graphical