Enhancement of dynamic visual acuity using transcranial alternating current stimulation with gamma burst entrained on alpha wave troughs
Behavioral and Brain Functions volume 19, Article number: 13 (2023)
Cross-frequency phase-amplitude coupling (PAC) of cortical oscillations is observed within and across cortical regions during higher-order cognitive processes. Particularly, the PAC of alpha and gamma waves in the occipital cortex is closely associated with visual perception. In theory, gamma oscillation is a neuronal representation of visual stimuli, which drives the duty cycle of visual perception together with alpha oscillation. Therefore, it is believed that the timing of entrainment in alpha-gamma PAC may play a critical role in the performance of visual perception. We hypothesized that transcranial alternating current stimulation (tACS) with gamma waves entrained at the troughs of alpha waves would enhance the dynamic visual acuity (DVA).
We attempted to modulate the performance of DVA by using tACS. The waveforms of the tACS were tailored to target PAC over the occipital cortex. The waveforms contained gamma (80 Hz) waves oscillating at either the peaks or troughs of alpha (10 Hz) waves. Participants performed computerized DVA task before, immediately after, and 10 min after each stimulation sessions. EEG and EOG were recorded during the DVA task to assess inter-trial phase coherence (ITPC), the alpha-gamma PAC at occipital site and the eye movements.
tACS with gamma waves entrained at alpha troughs effectively enhanced DVA, while the tACS with gamma waves entrained at alpha peaks did not affect DVA performance. Importantly, analyses of EEG and EOG showed that the enhancement of DVA performance originated solely from the neuromodulatory effects, and was not related to the modulation of saccadic eye movements. Consequently, DVA, one of the higher-order cognitive abilities, was successfully modulated using tACS with a tailored waveform.
Our experimental results demonstrated that DVA performances were enhanced when tACS with gamma bursts entrained on alpha wave troughs were applied over the occipital cortex. Our findings suggest that using tACS with tailored waveforms, modulation of complex neuronal features could effectively enhance higher-order cognitive abilities such as DVA, which has never been modulated with conventional noninvasive brain stimulation methods.
Theta (4-7 Hz), alpha (7-13 Hz), and gamma (>30 Hz) band activities in the occipital area have been reported to play a critical role in visual perception [1,2,3,4,5]. Specifically, a characteristic commonly observed in previous studies is phase-amplitude coupling (PAC) between slow (theta or alpha) and fast oscillations (gamma). In particular, alpha-gamma PAC is believed to be closely related to visual attention and cognition [1,2,3,4], whereas theta-gamma PAC is more relevant to the capacity to store visual representations [5, 6].
Gamma waves are believed to be responsible for inter-regional communication and information encoding, and alpha waves are known to rhythmically inhibit these processes [7, 8]. It is quite interesting, however, that coupling between the two waves with seemingly contradicting function plays an important role in visual perception. Theories suggest that rhythmical inhibition by alpha oscillation limits and prioritizes neuronal processing, and at the same time, a “duty cycle” is driven by gamma waves . The duty cycle refers to the timing when the gamma oscillation is entrained on an oscillatory cycle of alpha waves (e.g., peak or trough) when a certain neural process occurs. Because the alpha waves serve as an inhibitory rhythm, neuronal firing is generally inhibited at the peaks of an alpha cycle, and the opposite is true at the troughs of an alpha cycle. Therefore, gamma waves cannot drive a duty cycle at the peaks of the alpha wave. In contrast, gamma waves can initiate duty cycles as inhibitory alpha waves enter their descending period. Therefore, stronger gamma waves are observed at the troughs of alpha waves [1, 7]. In summary, the entrainment timing of fast oscillating waves on slow waves is critical for neural processing in the brain.
The importance of entrainment timing in the coupling between fast and slow brain oscillations has been confirmed in a number of studies that examined information processing within a cortical region and between multiple cortical regions. For example, the performance of a visual perception task was enhanced when visual stimuli were presented over troughs of the occipital alpha , which was also observed in the visual cortex of monkeys . Likewise, information transfer between the parietal and frontal regions was enhanced when parietal gamma waves were entrained at the troughs of the fronto-medial theta waves . This evidence stresses the importance of the timing of coupling between fast and slow oscillations during higher-order cognitive processes.
Modulating the timing of gamma entrainment in slower waves over certain cortical regions could further confirm the importance of entrainment timing in neuronal processing. Such modulation could be achieved by transcranial alternating current stimulation (tACS), as tACS is known to directly influence neural activity by interacting with endogenous oscillations [11, 12] and effect large-scale cortical networks with unique resonance dynamics . That is, tACS can entrain brain oscillations to specific waveforms by injecting weak alternating currents (AC) through electrodes attached over the scalp [14, 15]. Previously, only one study has focused on modulating the entrainment timing using tACS . While conventional tACS employs sinusoidal AC with a single frequency [10, 17, 18], the previous study delivered a customized AC with multiple frequencies, and reported successful modulation of brain connectivity . In this study, an injection current with 40 Hz gamma waves entrained over the peaks of theta waves enhanced the working memory performance. However, the injection current with 40 Hz gamma waves entrained over the troughs of theta waves did not show any significant effect. This study reiterated the role of PAC and proved that an elaborate stimulation protocol could modulate sophisticated neuronal features and eventually affect behavioral performance.
In the present study, we attempted to demonstrate that adjustment of entrainment timing in occipital alpha-gamma PAC using tACS with customized waveforms can affect the dynamic visual acuity (DVA) performance of individuals. To this end, two customized injection current waveforms were evaluated—gamma waves (80 Hz) entrained over the peaks of alpha waves (10 Hz) and gamma waves entrained over the troughs of alpha waves (hereafter referred to as the peak and trough conditions, respectively). The effect of stimulation on DVA performance was quantified by measuring DVA performance before and after both conditional and sham stimulation conditions. We hypothesized that the trough condition would strengthen the information processing of visual inputs in the occipital cortex, while the peak and sham conditions would not lead to any significant performance change. Because both image processing and visual tracking via saccadic movements are critical components of DVA [19, 20], horizontal electrooculograms (EOG) were also recorded and analyzed to observe any saccadic movement during the task. Finally, to eliminate the possibility that DVA performance was affected by the coincidental presentation of visual stimuli during certain times of occipital alpha, an electroencephalogram (EEG) was recorded from the occipital site.
Twenty young volunteers who had corrected to normal vision participated in the current study (ten males and ten females; mean age: 22.94 ± 2.24 years). Participants went through initial screening by identifying a gap direction of static Landolt’s C ring with gap size of 3 minimum angle of resolutions (MARs), or the smallest size of visual stimuli used in the behavioral task employed for this study. All the participants successfully identified gap directions of every static stimuli. Individuals with any identifiable neurological disorder, head injury, or personal or family history of psychiatric illness were excluded. The study protocol was approved by the Institutional Review Board (IRB) of Hanyang University, South Korea (IRB No. HYU-2020–010). The participants gave their written informed contents before the experiments. Subjects participated in three stimulation sessions, with each session (peak, trough, and sham) at least 72 h apart. No participants reported adverse symptoms, such as itchiness or phosphene.
TACS with tailored waveform
Single-channel tACS with customized current waveforms and sham stimulation were applied to each participant on three separate days, with the current waveforms applied over the electrode at Oz. All the sessions were counterbalanced and randomized. The peak and trough sessions indicate the timing at which gamma (80 Hz) waves were entrained over the alpha (10 Hz) waves in the stimulation current waveform. The peak-to-peak amplitude of the stimulation current was 3 mA, with three cycles of 1.2 mA, 80 Hz entrained over an interval π/8, 3π/8 (peak) or interval 5π/8, 7π/8 (trough) of 1.8 mA, 10 Hz AC. For the sham condition, 10 Hz AC was ramped up to 3 mA and immediately ramped back to 0 mA once the current reached the peak, with 30 s of ramping periods. All stimulations were delivered using Starstim8 of Neuroelectrics (Barcelona, Spain).
The stimulation current was delivered through saline soaked, circular electrodes with an area of 25 cm2 placed over Cz and Oz of the 10–20 international EEG system. The stimulation montage was validated using computer simulation based on finite element method (FEM). The finite element head model was constructed from a sample MRI data (Fig. 1B), and the electric fields were computed using solver embedded in COMETS 2 . The maximum electric field delivered by our setup was 0.32 V/m, which was sufficient to modulate neuronal activities [22, 23]. The electric field distribution over the cortex is illustrated in Fig. 1C. The stimulation lasted 20 min, excluding the ramping times. The ramping times were 60 s, with a ramp-up and ramp-down of 30 s each. The participants underwent three DVA task sessions: pre, post0, and post10. Pre, post0, and post10 sessions denoted the task sessions performed prior to the stimulation, immediately after the stimulation, and 10 min after the stimulation, respectively. Three participants were excluded from the analyses because they could not participate in all three stimulation (2 participants) sessions or was accidentally informed of stimulation condition (1 participant). Additionally, one participant was excluded for the analysis of 3 MARs trials since the size-specific accuracy of a participant did not reach the chance level (25%) in all the task sessions under a stimulation condition.
A computerized DVA task was constructed using C# and Unity based on a previous study . During the task, participants were asked to indicate the direction of the gap of a Landolt’s C-ring moving at a constant speed by using the arrow keys of the keyboard. For each trial, the stimulus presented was random in speed (from 200 to 700 degrees/s, with a step of 100 degrees/s), movement direction (left to right or vice versa), gap direction (up, down, left, and right), and size (gap size of 3, 4, and 5 MARs). All possible combinations of random factors were 144, which was the number of trials in one session. When no stimuli were presented, a fixation cross appeared on the screen. The ISI was also random, ranging from 1500 to 2500 ms. The movement of the visual stimuli covered the visual angle ranging from -10° to 10°. This range of visual angles failed to induce ocular saccades during DVA performance . To maintain the visual angle, the stimuli were kept constant, and the distance between the subjects and the center of the monitor was fixed at 70 cm. To display the stimuli as fluently as possible, a 240 Hz monitor was used. A flowchart of the task session is illustrated in Fig. 2. Participants performed three sessions of computerized DVA tasks under each stimulation condition: prior to the stimulation (pre), immediately after the stimulation session (post0), and 10 min after the stimulation session (post10).
Initially, the participants underwent a screening test, wherein they were asked to identify the direction of the gap of ten 3 MARs stimuli in a static state. During the main sessions, both overall accuracy and accuracy, specific to the stimulus size, were evaluated. The experimental protocol and the schedule of tasks are illustrated in Fig. 2.
EEG recording and analysis
During all task sessions, EEG was recorded. Of the 17 participants who completed the experiment, data from one subject were excluded from the analysis due to recording errors. The EEG data were recorded over the Oz position (the electrode at Oz site was replaced as necessary, i.e., from EEG electrode to the stimulation electrode after the pre session) according to the International 10–20 EEG system with reference attached over the right mastoid, at a sampling rate of 2,048 Hz. The recorded data were high pass filtered at 1 Hz, and 60 Hz components were notch filtered to remove power noises. In all the analyses, trials with an EEG amplitude higher than 100 µV were excluded (maximum of 14 trials were removed, from one subject in post0 session of peak stimulation condition) from the analysis to eliminate trials contaminated with noise. For trials that were not contaminated, the inter-trial phase coherence (ITPC) and power spectrum was computed and averaged across trials for each participant. The ITPC was computed using newtimf function of EEGLAB in MATLAB version 2019b , with frequency range of 1 to 100 Hz with a step size of 1 Hz. The power spectrum was computed based on fft function in MATLAB. Finally, the PAC was computed using a MATLAB toolbox available at https://data.mrc.ox.ac.uk; the PAC was computed for phase frequency of 4 Hz to 20 Hz with a step size of 1 Hz and amplitude frequency of 30 Hz to 100 Hz with a step size of 5 Hz. All the features were computed for the time window spanning -1000 ms to 0 ms, where 0 ms was the stimulus onset.
All the statistical analyses were conducted using Matlab 2019b. For the behavioral data, both the qq-plot and data distribution indicated that the data did not follow normal distribution, as confirmed by the Shapiro–Wilk test (see Supplementary information for details). Therefore, a nonparametric analysis was employed. For behavioral performance data, Friedman’s test for within factor ‘session’ was performed to examine the overall and size-specific accuracy under each stimulation condition. Additionally, Friedman’s test was performed for within factor ‘Stimulation condition’ to assess the overall and size-specific accuracy of pre sessions to evaluate whether there was any difference between the baseline conditions for each day. Then, a post-hoc analysis of Wilcoxon’s signed-rank test was performed if necessary. Finally, multiple corrections of p-values were made using false discovery rate (FDR).
For EEG data, statistical analyses were conducted for the ITPC, 10 Hz power, 80 Hz power, and PAC. For every feature, Friedman’s test was performed for within factor ‘session’, and subsequent Wilcoxon’s signed rank test was performed if necessary. All the p-values acquired from the Wilcoxon’s signed rank test was corrected using FDR. Because stimulation parameters targeted alpha (10 Hz) and high gamma (80 Hz), appropriate windows of interests were selected for each analysis.
For ITPC, six windows of interests for the statistical analyses were selected: all possible combinations between two frequency windows of 7 − 13 Hz and 70 − 90 Hz and 200 ms time windows starting from − 600 ms, − 400 ms, and − 200 ms. The time windows were chosen to represent time windows prior to the visual stimuli onset, as phase alignment during visual perception is reported to occur prior to the stimulus onset. For PAC, the statistical analyses were conducted for a phase frequency bin of 7 − 13 Hz and amplitude frequency bin of 70 − 90 Hz. The mean PAC value for the window of interest was computed for each session under the stimulation conditions, and Friedman’s test was performed. Since Friedman’s test did not yield any significance, no post-hoc analysis was conducted.
The simulation results revealed that the maximum electric field amplitude induced over the cortex was 0.32 V/m when 1.5 mA was applied over the Oz electrode (Fig. 1C), which is strong enough to entrain neuronal activities [25,26,27]. Note that the simulation was conducted assuming that maximal current was applied over the Oz electrode.
Because the data did not follow normal distribution, nonparametric methods were used for all statistical analyses. Exemplary quantile–quantile plot and distribution of the data are illustrated in Supplementary information (Additional file 1: Fig. S1). More detailed information about the task is described in the Methods section and Fig. 2. Friedman’s tests with within-factor ‘sessions’ revealed significant differences in all size-specific and overall accuracies under trough conditions (3 MARs: χ2 = 10.32, p < 0.01; 4 MARs: χ2 = 7.85, p = 0.02; 5 MARs: χ2 = 8.39, p = 0.015; overall: χ2 = 13, p < 0.01) and the accuracy of 5 MARs stimuli under the sham condition (χ2 = 6.64, p = 0.04). Additionally, the post-hoc analysis revealed significant differences between the accuracies of pre-post0 and pre-post10 only under the trough condition for all the measures (between pre-post0: p < 0.01 for 3 MARs, 4 MARs, and the overall accuracy, and p = 0.026 for 5 MARs; between pre-post10: p < 0.01 for 3 MARs, 4 MARs, and the overall accuracy, and p = 0.011 for 5 MARs). However, no significant difference was observed between the accuracies of 5 MARs under the sham session (p > 0.14). In addition, there were no significant differences between the accuracies of the different pre-sessions (3 MARs: χ2 = 1.66, p = 0.44; 4 MARs: χ2 = 3.31, p = 0.19; 5 MARs: χ2 = 1.61, p = 0.45; overall: χ2 = 2.38, p = 0.3). These results indicate that there was no difference in the participants’ baseline performance, regardless of the stimulation conditions. All p-values presented were corrected using the FDR. The behavioral results are shown in Fig. 3.
EEG was recorded during each task session. EEG was recorded at Oz, with the reference attached over right mastoid. To examine whether the changes in behavioral performance was due to the previously reported pre-stimulus phase realignment, ITPC was computed (Fig. 4). For the windows of interest, no significant difference was observed for post0 and post10 sessions compared to pre session, regardless of the stimulation conditions (χ2 < 5.38, p > 0.068 for each comparison, per Friedman’s test, where the complete statistics are displayed in Table. 1). The windows of interests covered time windows prior to the stimulus onset, as significant phase alignment is usually observed prior to the stimulus onset during visual perception . This implies that the behavioral changes were not caused by coincidental alignment of pre-stimulus phase. Furthermore, the ITPC was computed separately for correct and missed trials, as the significant phase alignment was better observed in correct trials . However, significant increase in phase alignment due to different stimulation conditions were not observed for both correct trials and missed trials (depicted in Additional file 1: Fig. S2).
To further test the effect of stimulation conditions, the additional features during the task was observed: i) the power spectrum of 10 Hz and 80 Hz and ii) the PAC were computed. Firstly, the spectral power of 10 Hz significantly increased only after the trough stimulation condition, in both post0 and post10 sessions compared to the pre session (Fig. 5A-B). For clarity of display, error bars were omitted; the power spectrum with standard error shaded is illustrated in (Additional file 1: Fig. S3). While Friedman test for within factor ‘session’ showed significant difference between sessions for each of stimulation conditions (sham: χ2 = 6, p = 0.05; peak: χ2 = 6.5, p = 0.039; trough: χ2 = 12.13, p < 0.01), subsequent post-hoc analysis of Wilcoxon’s signed rank test with multiple correction using FDR showed significance only under the trough stimulation condition (between pre-post0 and pre-post10, respectively, sham: p = 0.2 and p = 0.17, peak: p = 0.21 and p = 0.08, and trough: p < 0.01 and p = 0.011). No significance was found between post0 and post10 sessions, regardless of stimulation conditions (p > 0.19). All the p-values reported are corrected using FDR. Additionally, no significance was found for 80 Hz in Friedman test, albeit marginal significance was observed for the trough condition (sham: sham: χ2 = 0.38, p = 0.83; peak: χ2 = 2, p = 0.37; trough: χ2 = 4.88, p = 0.09).
Secondly, as in Fig. 6, relatively strong PAC between alpha and high gamma was observed throughout the behavioral performance. However, Friedman’s test for factor ‘session’ showed no significant difference between PAC of alpha (7 ~ 13 Hz) and high gamma (70 ~ 90 Hz) during post0 and post10 sessions compared to the pre sessions (sham: χ2 = 4.63, p = 0.1; peak: χ2 = 0.13, p = 0.94; trough: χ2 = 5.38, p = 0.07). The PAC results indicate that while alpha-high gamma coupling is related to behavioral performance, stimulations did not alter alpha-high gamma PAC at the occipital site. This result is in line with that of spectral power analysis, as amplitudes of gamma were not affected by stimulation.
In this study, we sought to improve DVA performance using tACS with customized AC waveforms and found that the modulation of spatiotemporal features of alpha-gamma PAC at the occipital site could successfully enhance DVA performance. It is widely believed that visual perception is controlled by the inhibitory cycle of occipital alpha waves [29,30,31,32]. Specifically, visual inputs are most efficiently processed during the descending period, or troughs, of alpha waves [1, 7]. It could be argued that to assess such behavioral performance related to visual perception, the employment of static visual stimuli might be sufficient rather than presenting a dynamic visual stimulus; however, improving the identification of static visual stimuli would be related more to vision itself than to visual processing mechanisms related to occipital cortex.
The main finding of our stimulation study was in agreement with previous studies, as DVA performance was enhanced only when gamma oscillations were entrained on the troughs of the alpha waves. For the trough condition, 80 Hz gamma waves were entrained over the [17π/16, 31π/16] period of the 10 Hz alpha phase, whereas the gamma waves were entrained over the [π/16, 15π/16] period for the peak condition. We chose 10 Hz and 80 Hz as the stimulation parameters because 10 Hz is a widely used frequency when targeting alpha oscillations [33, 34] and it is reported that high gamma (> 50 Hz) being coupled with alpha at the posterior cortex is critical during visual tasks . It could be debated whether weak AC delivered transcranially can modulate such intricate cortical rhythms . However, an ephaptic coupling hypothesis  and many other reports [15, 38,39,40] underpin the feasibility of such modulation. Therefore, we believe that the improvement in DVA performance in our study originated from the modulation of entrainment timing in the alpha-gamma PAC at the occipital site.
Since previous studies reported prestimulus oscillatory phase affecting visual perceptions, we set the inter-stimulus interval (ISI) as a random value between 1.5 and 2.5 s in an effort to randomize the prestimulus oscillatory phases. Furthermore, we recorded EEG signals at Oz during the task sessions and analyzed the ITPC from – 1000ms to 0 ms from stimulus onset. ITPC were not affected by stimulation, as evidenced by the lack of a significant difference between sessions after and prior to each stimulation. Therefore, it was confirmed that the visual stimuli of the DVA task was not presented at specific oscillatory phases. This further supports that the observed enhancement of DVA performance was not a product of coincidental alignment of the visual stimuli to a certain phase of the occipital alpha.
Although the stimulation parameters included both alpha (10 Hz) and gamma (80 Hz) components, the power spectrum showed that only the power of 10 Hz was enhanced when trough stimulation was applied, while the 80 Hz component was not significantly affected by stimulations. Therefore, it could be argued that only applying 10 Hz stimulation might be sufficient to target causal oscillatory features for DVA performance. However, we firmly believe that this argument is not true based on the following two reasons: Firstly, the peak stimulation condition did not enhance either DVA performance or 10 Hz power, although the peak stimulation parameter also included 10 Hz. Secondly, the previous literature that employed a similar tACS waveform yielded similar behavioral and EEG results to ours, where behavioral performances were dependent on the frequency of the higher frequency component in the stimulation waveform while EEG functional connectivity for the low frequency component over cortical regions was increased only when the stimulation was effective . Note that our stimulation amplitude ratio between the phase and amplitude frequencies (10 Hz and 80 Hz, respectively) was replicated from the study.
To the best of our knowledge, no previous study has explored the causality between the different amplitudes of the phase and amplitude frequencies and cognitive measures. Although, given that the brain oscillations naturally exhibit higher power in the low frequencies (i.e., alpha range, 7–13 Hz) than high frequencies (i.e., gamma range, 30–100 Hz), it seems feasible that the low frequency component (10 Hz) in our stimulation waveform has higher amplitude than the high frequency component (80 Hz). Granted, the optimal ratio or amplitude of each frequency component when designing stimulation waveform likely depends on individual responsiveness to stimulations. Such individualization of stimulation amplitude is extremely challenging to achieve in most experimental designs, including the current study. Furthermore, we aimed to modulate frequency coupling in a single cortical region by manipulating temporal dynamics of the tACS waveforms. Combined, while the amplitudes of each frequency component constituting the customized tACS waveform might be important, a focus should be placed on the temporal characteristics and amplitude of the entire waveform when evaluating the waveform.
In an effort to examine whether the increase in alpha power truly affected behavioral performance, we also computed event-related spectral perturbation (ERSP) during the task. The results indicated that the trough stimulation condition significantly increased ERSP at the alpha band prior to the onset of visual stimuli, further underpinning the trough stimulation condition only affected alpha band (see Additional file 1: Fig. S4 for details).
There are two key components of the DVA: visual information processing and visual search through saccadic movements. Several previous studies that compared DVA performance between normal people and athletes reported that faster saccadic movements generally result in better DVA performance [19, 20]. To further validate whether the tACS with a tailored waveform was the only factor involved in the enhancement of DVA performance, we observed saccadic movements from EOG signals recorded during the entire task. Since we recorded EOG only during the task, we were unable to statistically claim that there was no eye movement. However, saccadic movements are rapid and thus could be easily detected by visual inspection. In this light, no significant saccadic movement was observed during any task sessions (Additional file 1: Fig. S5), indicating that the DVA performance was unaffected by saccadic movement changes.
The causal role of brain oscillations in cognitive performance has been widely studied [41,42,43]. Specifically, our results are in agreement with those of previous studies that emphasized the close relationship between the entrainment timing of cross-frequency PAC and behavioral performance [4, 9, 10]. In the present study, we demonstrated that modulation of the entrainment timing of alpha-gamma PAC using tACS with a tailored waveform could successfully alter visual processing performance, particularly the DVA performance. Nevertheless, we did not conduct any neuroimaging study that might quantitatively evaluate the brain network dynamics, especially the fronto-occipital network , altered by tACS. Further exploration of the causality between brain network dynamics and the modulation of entrainment timing in PAC should be performed using neuroimaging methods.
This study attempted to modulate the entrainment timing of gamma oscillations at alpha oscillations using tACS with tailored waveforms. Our experimental results demonstrated that tACS over the occipital cortex with gamma bursts entrained on alpha wave troughs could effectively enhance DVA. Our findings suggest that using tACS with tailored waveforms, modulation of complex neuronal features could effectively enhance higher-order cognitive abilities such as DVA, which has never been modulated with conventional noninvasive brain stimulation methods. It is expected that our findings may provide useful insights for developing new interventions based on noninvasive brain stimulation.
Availability of data and materials
The measured data and code can be conditionally accessed upon request to the corresponding author due to privacy and conditions of approvement by the Institutional Review Board of Hanyang University.
Phase amplitude coupling
Transcranial alternating current stimulation
Noninvasive brain stimulation
Dynamic visual acuity
Minimum angle of resolution
Finite element method
Inter-trial phase coherence
False discovery rate
Event-related spectral perturbation
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This research was supported by the National Research Foundation of Korea (NRF), funded by the Korea government (MSIT) (Nos. 2019M3C7A1031278 & RS-2023-00266075).
Ethics approval and consent to participate
All the participants were provided with a detailed explanation of the experimental protocols and signed a written informed consent form. The study protocol was approved by the Institutional Review Board of Hanyang University, South Korea (IRB No. HYU-2020-010).
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The authors declare no competing financial interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Cite this article
Park, J., Lee, S., Choi, D. et al. Enhancement of dynamic visual acuity using transcranial alternating current stimulation with gamma burst entrained on alpha wave troughs. Behav Brain Funct 19, 13 (2023). https://doi.org/10.1186/s12993-023-00215-w


Below is a non-exhaustive list of instruments we use in the field.
Ionicon PTR-ToF-MS 4000
The PTR provides simultaneous measurements of hundreds of VOCs with high precision. Recent deployments of our instrument include:
- Jan-March 2020: COALA, New South Wales, Australia (wildfire smoke composition)
- Nov-Dec 2021: Chamber studies at CalTech (emissions and oxidation of volatile chemical products)
- June-Aug 2020, 2021, 2022: Atlanta, Georgia (urban VOC speciation and trends)
Ionicon PTR-ToF-MS technical specifications: here.
Pandora 1S spectrometer systems
Measurements from Pandora spectrometers can be used to track total column and vertical profiles of key trace gasses such as NO2 and formaldehyde. We have three Pandora systems deployed in Atlanta. These systems are paired with ground-based observations to provide a complete picture of surface and total column trace gas levels.
The large and growing Pandonia global network is a multi-institutional effort to build satellite validation infrastructure.
This cavity-ringdown instrument provides continuous observations of formaldehyde with high advertised precision and accuracy. The instrument is currently deployed in Atlanta at a Photochemical Assessment Monitoring Station (PAMS) site as part of a long-term effort to understand VOCs and their oxidation in the urban environment.
Picarro G2307 technical specifications: here.
Aeris Ultra and Pico formaldehyde analyzers
These small-footprint, portable instruments are part of our urban formaldehyde monitoring plan. Paired with our Pandora spectrometers, we use the Aeris Analyzers study spatial gradients in urban HCHO concentrations.
Aeris Ultra/Pico technical specifications: here.


Last year, Sirin Labs launched the Finney Smartphone, the first mobile phone on the market to function within a specially developed blockchain ecosystem. The company has also developed a Blockchain-All-In-One-PC.
Let’s take a closer look at what this Bitcoin news has to offer and how it could change the way we communicate
Blockchain will remain one of the buzzwords in 2018 when it comes to technological innovations designed to make our lives simpler, more convenient and more efficient. Driven by the use of crypto currencies, which have recently been on everyone’s lips thanks to the recent Bitcoin news high flight, the review of this technology is gradually making its way into the middle of society. In addition to institutionalized adaptations, such as in logistics or the energy industry, the private use of blockchain-based solutions is becoming increasingly important.
A suitable example of this is the Finney smartphone, a mobile phone issued by the Israeli blockchain start-up Sirin Labs. Sirin Labs has developed its own ecosystem, Finney, to combine consumer hardware with blockchain technology. Sirin denounces that the current generation of interconnected electronic devices places too little emphasis on security and sacrifices it in favor of optimizing the user experience. For a sustainable digital economy, however, sufficient security of user data when using a device is indispensable. The blockchain named after Hal Finney, one of the first bitcoiners, is intended to remedy this situation.
Sirin Labs recently launched two products that can be used within the Sirin ecosystem. The Finney smartphone is marketed as the first blockchain-enabled mobile phone and can be purchased for around 1,000 US dollars. The Finney Blockchain All-In-One PC is said to be a bit cheaper for about 800 US dollars. Both devices will run on the Android-based open source operating system Shield OS, which is programmed to support blockchain applications such as an integrated cold storage crypto wallet, secure access to crypto exchanges and encrypted P2P resource sharing.
The devices also have their own DApps
The Finney smartphone is not the first mobile phone developed by Sirin Labs. In 2016, the luxury Solaris smartphone came onto the market for $14,000. Here, too, the focus was on the security of user data, but this early version did not yet include a blockchain solution. In addition, the expensive purchase price prevented the device from becoming seriously established. Instead, the Finney smartphone is designed for the mass market and has the ambition of becoming one of the pioneers of a new generation of smartphones.
Last year, Sirin Labs raised more than 150 million US dollars for the further expansion of the Finney Blockchain ecosystem, far exceeding its target of 100 million. For the acquisition of the products as well as the use of the Finney network, the SRN token exists since the ICO that ended last week, which will have contributed significantly to the financing of the project. Sirin Labs had announced its intention to develop the smartphone in the case of an income of 50 million US dollars, for the development of the PC the figure of 75 million US dollars had been spent.
With the development of the first blockchain-enabled devices, Sirin Labs aims to take electronics into the blockchain era and create a customer-focused, secure open source product. Finney smartphones and Finney PCs thus create an interface between hardware and blockchain technology, between electronics and digital, via the Sirin ecosystem. This innovation could represent the next logical step in the evolution of the smartphone by flanking permanent networking and availability with the self-management of one’s own data.


Photo credit: SpaceX
SpaceX hasn’t yet performed a successful barge landing.
Here we go again: SpaceX will attempt to launch the SES-9 mission on a Falcon 9 rocket today for the fifth time, together with a daring attempt at a landing.
The mission is scheduled to launch this evening, with the launch window opening at 6.35 p.m. EST (11.35 p.m. GMT) and closing at 8.06 p.m. EST (1.06 a.m. GMT tomorrow), from Cape Canaveral Air Force Station in Florida. Four previous attempts at launching have had to be scrubbed due to issues with the rocket and the weather.


Mendeley, the system that makes research easier and more fun, has announced a joint competition with PLoS, a library of scientific research, to award a series of prizes to developers who build interesting apps on top of their APIs.
The interesting thing about this competition is that the app being built could improve the lives of scientists and researchers, potentially improving the quality of research or the findings. Who knows, maybe your entry will help to change the world?
First prize is £10,000.00 and AWS credits, second prize is £5,000.00 and AWS credits, and third prize is £1,000.00 and a Parrot AR Drone (remote controlled flying toy controlled via iPhone). So the prizes are definitely worth going for.
This is very timely considering the upcoming Launch48 Moldova and Launch48 Kingston events where new startups could integrate and use these APIs. If you’re interested you can get an API key and enter at http://dev.mendeley.com/api-binary-battle/


on a chalet in boykovo village
A hybrid solar PV system, which we built on a chalet in the village of Boykovo, in a place that currently has no power supply.
The system is equipped with 3 pcs. CanadianSolar 265Wp photovoltaic panels, an FSP 24/3000 hybrid inverter and Monbat MVR190 200Ah AGM batteries. A generator is also connected to help the system on cloudy days when the energy from the solar panels is not sufficient


Berowra Waters is among the most beautiful places in the world. Many properties overlook the stunning waterways called Berowra Waters. The services of a trusted, local electrician is required, no matter where you live. Especially at times when you move into a new house or upgrade your current one. BSK Data & Electrical gives superb electrical services that are designed to fit all your needs.
Electrical Services That We Offer in Berowra Waters
BSK Data & Electrical is a local company with loads of experience in electrical services. Our team can handle any electrical job.
Our electrical services in Berowra Waters include:
Wiring Design and Reconstruction
If the house you’re living in is older, the wiring is likely outdated. These older power systems can’t cope with modern electronics and appliances’ higher power demands. Old appliances can heat the wiring. Especially when they’re used at the same time. This could melt the insulation and cause an electrical fire or shock. A good way to avoid this from occurring is to get your wiring up to date. We make sure that all the electrical installations are updated. We also confidently handle the wiring of new builds.
Power Point Repair and Installations
Each room in the house needs power points. The amount required rests on the number of equipment, gadgets, and electrical appliances that are planned to be used. Power points get a lot of use daily. Choosing premium ones is vital. Having them installed in your home by a skilled electrician will ensure a safe and detailed job done. No job is too small for us here at BSK Data and Electrical.
Replacement And Installation of Circuit Breaker
Your home’s electricity comes in through the meter box. It will then be fed to different rooms and areas around your home as required. Each power circuit is covered by a circuit breaker that controls the power flowing through it. This protects the circuits from voltage surges, appliance faults, and overload. Circuit breaker installations are a regular part of our day here at BSK Data and Electrical.
The main switch box controls the flow of electricity into varied parts of a property. We can replace switches, repair them, as well as install them.
In addition to these services, our team of trained Berowra Waters electricians also provide:
Ceiling fan assembly
Power protection solutions
Integrated security lights
We also design and set up all types of housing electrical projects, including the installation of electric gate motors.
Installations of Outdoor Lighting
BSK Data and Electrical is a company that can help you with a complete solution for your outdoor lighting. We are a local business in the Berowra Waters area. We provide residential electrical services with expertise, skill, knowledge, and good old fashioned courtesy.
Lighting up your yard and garden areas at night really takes your property to the next level. We offer top-notch outdoor lighting services. We can also add features such as paver lights, lamp posts, and more.
We suggest using LED bulbs and fixtures which give energy-efficient light and are durable. Well lit outdoor areas reduce the chance of trespassers, vandals, burglars, and other unwanted elements.
Why Should You Choose Us for Electrical Services?
We pride ourselves on being able to offer cost-effective electrical services to our clients. Berowra Waters homeowners are pleasantly surprised when we bring our services to them. We always clean up after ourselves – there will be no sign that a trade has been present other than for the improvements that have been made.
Know Your Local Electrician
Your local electrician is BSK Data & Electrical. Look no further the next time you want Berowra Waters electrician services. Phone us on 0447 730 993 if you need more info or would like to book our expert services. You can also use this online form to send us your questions.


Coastline Marine is proud to be able to supply and install Fusion Marine entertainment systems. Fusion offer a variety of systems within their range to suit all needs and budgets. Fusion's range offers some fantastic features, including; touch screens, ethernet, wifi, bluetooth and NMEA 2000 connectivity, multi-zone technology (up to four zones), televisions, speakers in varying designs and colours, VHF monitoring through stereo speakers, remote controls for the flybridge or cabin areas, amplifiers and subwoofers, USB and video playback and iPod / iPhone interface. A number of Fusion entertainment systems can also be integrated with Garmin marine multifunction, navigation and GPS systems. We can even fit systems to your jet ski! Fusion's Apollo series offers the first Marine stereo touchscreen to hit the market and the Fusion STEREOACTIVE is the world’s first purpose built watersport stereo. This is a fully waterproof portable watersport stereo. Featuring a unique Puck mount system that lets you attach the stereo to any paddle board, kayak, canoe, dinghy/tinny/jon boat or even Jacuzzi. To keep your smartphone safe during your excursion, FUSION has created the ACTIVESAFE which will securely house any smartphone, standard vehicle keys and any bank cards or change. For more information check out the product brochure here. Fusion also offer 'high-end' marine entertainment systems, which are purpose built for the marine-cabin environment of large boats. We can also upgrade your existing stereo system to include features like bluetooth connectivity.
Check out the videos below for more information. Contact us to purchase Fusion products or to discuss your marine entertainment needs at email@example.com or phone (03) 9708 2149


History Of Pcb
Dale Published November 2007 To Be Presented a1 WM 2008 PHOENIX WM Symposia, Inc. Congress initiated formal regulation of PCB management in the United States in 1976 with the regulation of PCBs by the Toxic Substances Control Act (TSCA), PL 94-469 (U. One such invention was a primitive circuit board, a precursor to the first true PCB. Download express pcb design software for free. Fighter's History is a traditional 2D fighter along the lines of the Street Fighter series. Flex Printed Circuits. Keyword: printed circuit board, history of PCB. In the winter time the bookmobile was jammed with snowbirds looking forward to their weekly reads. Klon Centaur circuit history. All this month we’re bringing you stories from North Carolina’s black history. History of Panama City Beach Public Library Library service for Panama City Beach started in the 1960's with weekly bookmobile runs from the Bay County Public Library in Panama City. A Closer Look at DDR5 Sockets. The History of Chlorinated Diphenyl (PCB's) by Peter Montague Annapolis, Maryland March 04, 1993 If you had to pick one chemical that best exemplified our modern situation, it might well be PCB's (polychlorinated biphenyls). HDI technology allowed for a denser design on the PCB and significantly smaller components. The ideal candidate will be an experienced functional manager, have a strong Printed Circuit Board design background, and a proven history of cross site / cross functional project management. A bit of history. PCB manufacturing. Introduction to PCB Design. Finding a piece of software to do printed circuit board design is much easier than it was a few years ago. Shop now!. Cornelius as one of three vice-Presidents. Innovative Concepts in Entertainment (ICE) - The Coolest Games on Earth. Holes were drilled into the material and then flat brass "wires" were riveted or bolted onto the board. Was founded by a mixture of EDA companies (Daisy Systems, Mentor Graphics), OEMs. In fact, the printed circuit board has taken a long journey to become the vital piece of electronics we use today. PCBs were banned in the U. The History of Chlorinated Diphenyl (PCB's) by Peter Montague Annapolis, Maryland March 04, 1993 If you had to pick one chemical that best exemplified our modern situation, it might well be PCB's (polychlorinated biphenyls). Multek is a value-added manufacturer of rigid, flexible and rigid-flex printed circuits, and offers printed electronics. PCB has a long history of development. 16 definitions of PCB. PCB's, once widely used as insulators and flame retardants, were found in the 1970's to be a cause of cancer and other illness in humans, including reproductive failures and birth defects. A Closer Look at DDR5 Sockets. So where did it all begin? Development of the methods used in modern printed circuit boards started early in the 20th century. So A1 would be the first version of the BOM and the first. A History of Printed Circuit Board Assemblies. PCB manufacturers were also quick to exploit the new opportunities. com ISO 9001/13485 FDA Registered Manufacturing Facility. Founded over a century ago in 1913, Peoples Community Bank is immersed in the rich history of the Northern Neck and Ferry Farm area of Virginia. will continue to challenge the world's most trusted PCB manufacturer. MORE ABOUT PCB CONTACT US. Learn about the complete history of EDA design automation and the evolution of PCB autorouting technology from the 1980s to today. PCB Design Software. Numerous boat houses, fishing docks, and piers offer valuable structure and cover to the fishes of Lake Worth. Here are some fascinating details you may not be aware of about the history of PCB. Santosh, founder of this Electronics Tutorial Website, is an Electronics Geek, Blogger and Young Entrepreneur. Every character has his ending sequence and his own stage. This led to frequent failures at wire junctions and short circuits when wire insulation began to age. The History of PCBs. From ocean to orbit and everywhere in between, Harris provides mission-critical solutions to connect, inform and protect the world. 2% from 2017 to 2022. We have been spending 25 years focusing on our customers, offering a professional service and tailored PCB products according to the diverse project needs. REGULATORY HISTORY The U. The Home Audio section contains information on home audio manufacturers and models. 1 Data Collection & Usability As an initial step, the PCB Screening Level Subgroup requested that all available PCB data sets generated through special studies by the DEQ Regional Offices be submitted to Central Office for ana lysis. 2% from 2017 to 2022. PCB articles must be properly marked and stored in an appropriate storage area. Despite the low concentrations, PCB bioaccumulation in biota could potentially produce chronic effects, such as developmental effects, reproductive failure, liver damage, cancer, wasting syndrome, and death. History of Buddhism Buddhist history begins with the life and teachings of an Indian prince named Siddharta Gautama, who lived around 500 BCE. Very few pedals can match the levels of mystery, hype and drama that surround the Klon Centaur Professional Overdrive, but then, very few pedals can match its tone, either. The Worst Greenhouse Gasses You Haven’t Heard Of. XP Power is committed to being a leading provider of power solutions, including AC-DC power supplies and DC-DC converters, high voltage power supplies and RF power supplies. As mechanically supports and electrically connects electronic components or electrical components using conductive tracks, pads and other features ethched from one or more sheet layers of copper laminated onto and/or between sheet layers of non-conductive substrate. They were intended to be used by the British and American military during World War II. 16 definitions of PCB. (UNEP, 2001, UNEP Draft 2004) Technology description: Hazardous waste incineration uses controlled flame combustion to treat organic contaminants mainly in rotary kilns. Generating the Right Data: Determination ~ of Aroclors Versus PCB Congeners C. The McMechen Street Car Barns, during demolition in 1959, to make wa y for the new Route 2. Holes were drilled into the material and then flat brass "wires" were riveted or bolted onto the board. com, India's no. This section is very helpful in getting information related to the elementary, secondary, higher secondary, higher and adult education etc. Newgrange Design is a Best-in-Class Embedded Systems and PCB Design services firm. 0 parts per million (ppm) in fish. The inventor of the printed circuit was the Austrian engineer Paul Eisler (1907–1995), who made one in England around 1936, as part of a radio set. For some designers, the PCB design will be a natural and easy extension of the design process. In this blog we share the history of the Printed Circuit Board (PCB) and ask what possible future applications can change the course of PCB manufacturing. Wally said that it wasn't really his title, it was given to him by the show organizers who wanted him to do a retrospective on the PCB industry over the years, and a look to the future. PCB is compliant with all government laws and regulations including the Fair Debt Collection Practices Act (FDCPA) and the Health Insurance Portability and Accountability Act (HIPAA). The illustrious history of the PCB Posted on March 1, 2016 March 1, 2016 by Stranco While printed circuit boards are an integral component of modern electronics today, their origin began in the early 20th century. This type of connector is designed to mate cable and PC board circuitry in wire-to-board devices. The essence of Human Resource Development is education, which plays a significant and remedial role in balancing the socio-economic framework of the country. The development history of PCB is very long. Welcome to the PCB Design Flow using OrCAD Capture CIS and PCB Editor 17. The Forged PCB Tours are not to be confused with the regular Forged PCB irons which are aimed more towards mid- to high handicappers. The PCB Rules And Violations panel. Harwin has been manufacturing high-reliability connectors and PCB hardware since 1952. Definition of PCB in Science & Medicine. When Congress created Idaho Territory in 1863, the new territory sprawled across an area one-quarter larger than Texas. By building upon the code portions you select, the application will provide valid choices for each of the five components of the product code (Industry, Class, Subclass. Scope: A brief history of where we have been Definition: Printed Circuit Board (PCB) or Printed Wiring Board (PWB) " Printed circuits were developed during World War II by the National Institute of Standards and Technology for use in the proximity fuze for artillery shells. This led to frequent failures at wire junctions and short circuits when wire insulation began to age. Who Made the First Printed Circuit Board?. A history of the Big Muff, from the Foxey Lady, to the Russian Sovteks, to the current USA re-issue. Its unique, patented technologies can reduce design cycles by 50 percent or more while significantly improving overall quality and resource efficiency. The Pakistan Cricket Board (PCB) is the central industry for cricket in Pakistan which deals with all the concerned matters of Pakistan cricket and International cricket. 2008 Published in 24th Waste Management Conference Prepared for the US. Despite the low concentrations, PCB bioaccumulation in biota could potentially produce chronic effects, such as developmental effects, reproductive failure, liver damage, cancer, wasting syndrome, and death. All this month we’re bringing you stories from North Carolina’s black history. Printed Circuit Board. History and Vision. How We Care. Works well. M&M Technology, Inc. It serves 2 primary functions. Harwin is a world class manufacturer of High-Reliability Connectors, Industry Standard Connectors, Board Level EMC Shielding and associated PCB Hardware. June 2014 Version Revisions to the PCB Q and A Manual (June 2014) About the PCB Question and Answer Manual: The PCB Q and A manual is a living document and is periodically revised and updated. Although printed circuit boards represent a major improvement over tube technology, they are not without fault. To help provide a sense of the short to long-term trend, included is an interactive Pacific City Financial stock chart which you can easily adjust to the time frame of your choosing (e. PCBs have been used since 1929, and many of the early manufacturers have gone out-of-business. PCB Design Tutorial by David L. pcb Fabrication of the Printed Wiring Board - A Brief History:. between PCB exposure levels and health effects. The first printed circuit boards (PCBs) can be traced all the back to the early 1900s and a patent for “printed wire. Monsanto's history really speaks for itself, and its current behavior tells us nothing has changed since the days of DDT, PCBs and Agent Orange. EPA Bans PCB Manufacture; Phases Out Uses [EPA press release - April 19, 1979] The Environmental Protection Agency today issued final regulations banning the manufacture of polychlorinated biphenyls (PCBs) and phasing out most PCB uses. Create PCB circuits for free with the most advanced features. Before the development of printed circuit boards electrical and electronic circuits were wired point-to-point on a chassis. With these, you can press into contacts on the PCB you want to program. In applications where fine conductive traces are needed, such as computers, PCBs are made by a photolithographic process, in a larger scale version of the way conductive paths in processors are made. Polychlorinated biphenyls were once widely deployed as dielectric and coolant fluids in electrical apparatus, carbonless copy paper and in heat transfer fluids. The development history of PCB has witnessed the development of world industry. The timeline of printed circuit boards - PCB Train. Naturally, the company is one of the biggest names in the PCB industry. Navy SPAWAR Systems Center. This landfill would accept PCB-contaminated soil that resulted from illegal dumping of toxic waste along roadways. In the picture above, there are traces that electrically connect the various connectors and components to each other. Who Made the First Printed Circuit Board?. Knowledgeable of modern PCB manufacturing processes. The development history of PCB is very long. They're found. Because PCBs are such complex chemicals, knowledge of their. THE REGULATION OF PESTICIDES IN BELIZE 20 YEARS, 20 DEFINING MOMENTS 1988 TO 2008. PCBs were discovered during the 19th century. The endstop inputs will tolerate at least 8V. The question often asked is why is this thickness specified and is it an industry standard? This is one of those topics that warrants looking at the history of PCBs as. The PCB Rules And Violations panel. Wally said that it wasn't really his title, it was given to him by the show organizers who wanted him to do a retrospective on the PCB industry over the years, and a look to the future. Gerber Files. To help provide a sense of the short to long-term trend, included is an interactive Pacific City Financial stock chart which you can easily adjust to the time frame of your choosing (e. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. History of PLCs. Anderson's Marina. How We Care. BGA components are packaged electronically into standardized packages that include a wide array of. Methods and structures are provided for implementing embedded wire repair for printed circuit board (PCB) constructs. The Z probe input improved to tolerate inputs up to 30V. Because PCBs are such complex chemicals, knowledge of their. PCB levels in sea water tend to be highest in waters near industrial areas. Money20/20 is the doorway to the epicenter of the Payments, Banking, Fintech and Financial Services ecosystem. Leaching tests confirmed that PCB 11 could be released from these materials into water. Case Studies in Environmental Medicine (CSEM): PCB Toxicity. The Pakistan Cricket Board (PCB) is the central industry for cricket in Pakistan which deals with all the concerned matters of Pakistan cricket and International cricket. The History and Basics of IPC Standards: The Official Standards for PCBs 2 years ago by Nick Davis Learn about the industry-adopted IPC standards that govern every step related to the design, assembly, inspection, testing, and documentation of printed circuit boards (PCBs). PCB Manufacturing by Fineline, a world leading provider of Printed Circuit Boards. These machine tools had just started to appear on the factory floors then. 5% non-dissolved PCB material or more than 50 parts per million total concentration of PCBs, it is considered a hazardous material regulated by the U. 1968 PCB poisoning event in Yusho, Japan leads to awareness of toxic effects of PCBs. This made PCB easier to use and increased its popularity. June 2014 Version Revisions to the PCB Q and A Manual (June 2014) About the PCB Question and Answer Manual: The PCB Q and A manual is a living document and is periodically revised and updated. Northwest Public Power Association (NWPPA) is a not for profit association of over 150 public/people’s utility districts, electric cooperatives, municipalities and crown corporations in the Western U. This type of connector is designed to mate cable and PC board circuitry in wire-to-board devices. In the Pauline Letters, creation has an equally important place. 92 KB System: MAME Downloads: 1,349 Rating: None yet. Printed Circuit Design and Fab online Magazine. It conducts electricity between component leads. However, the US military ended up incorporating PCBs into anti-aircraft shells. was established in August of 1967 by Robert W. Transistors had become commonplace in everything from radios to phones to computers, and now. To gain an appreciation for PCB technology, let's look at several significant moments in the history of circuit boards. Before the advent of the PCB circuits were constructed through a laborious process of point-to-point wiring. IPC History. Construction options include everything from simple single-sided. PCB on asus z170-a MB. in 1979 amid suggestions that these chemicals could have unintended impacts on human and environmental health. Title: PCDD/F and PCB history in dated sediments of a rural lake: Authors: Isosaari, Pirjo; Pajunen, Hannu; Vartiainen, Terttu: Publication: Chemosphere, vol. Prior to Mentor Graphics, he has served on the DxDesigner and PADS Customer Advisory Boards, and is the founder and manager of the DxDesigner Yahoo forum. If the Bill of Materials or Schematic changes but the PCB board does not, then there is no need to bump a revision level on the PCB. Fighter' History is a 2D fighting game, with a cast of 9 playable characters. Most boards nowadays are constructed from laminate material, with copper pre-applied to both sides. com ISO 9001/13485 FDA Registered Manufacturing Facility. Printed circuit boards have come a long way since their initial creation, many different small changes happened over their lifespan to create the PCB that is so useful today, being integral to many pieces of technology. Jones Page 3 of 25 3 Introduction You've designed your circuit, perhaps even bread boarded a working prototype, and now it's time to turn it into a nice Printed Circuit Board (PCB) design. In this blog we share the history of the Printed Circuit Board (PCB) and ask what possible future applications can change the course of PCB manufacturing. The Arc has been at the forefront of making change happen, both through advocacy and by supporting research efforts. The two year effort, to develop a unique and distinct certification, recognized the efforts and work done by recovering individuals in the community. Create PCB circuits for free with the most advanced features. PCB Solutions announces PCB Engineering, Design, and Layout Division A supplier of rigid, flex, and rigid flex printed circuits announces the latest addition of services to their portfolio: printed circuit board engineering, design and layout. Contact Gorilla Circuits at their offices world-wide. The patent they obtained in 1956 was assigned to the U. Produced and directed by Tobe Carey. When Congress created Idaho Territory in 1863, the new territory sprawled across an area one-quarter larger than Texas. Also, while vacuum tubes are easily removed for testing or replacement, pcb components. WDFW Publications. A load of an electrical circuit may be as simple as those that power home appliances like refrigerators , televisions, or lamps or more complicated, such as the load on the. 💡 Developed a PCB for a radio system in 1936. We provide services that impact more than 840,000 students on 1,220 campuses in over 8 counties in North Texas. 001) was created for a third edition. The advisory recommended that. the house stood kitty-corner across the square. The PCB Regulations (SOR/2008-273) came into force on September 5, 2008. The History of STORIS -- PCB proof in the paperwork -- Part 5 This is a link to the Environmental Assessment report from December 2006 prepared as the Coast Guard was getting ready to decommission CGC STORIS and CGC ACUSHNET. DDT is a chlorohydrocarbon and was made for controlling mosquitoes and other insects. Visit Last Call for gorgeous designer handbags, beautiful designer dresses and designer shoes from fashion's top names. Over the past half-century, the technological components of PCBs have been quantified to micro levels. A Gerber File is a file format used for PCB manufacturing. As the home of the Money Revolution we unite captains of industry, dreamers, trailblazers, innovative thinkers and fearless leaders that hold the keys to fundamental changes in the way the world uses, spends, borrows and moves money. to build up in the bodies of animals, particularly at the top of the food chain). Compared to PCB revision v1. This type of printed circuit board contains just one layer of substrate, or base material. In this game, you are a small boy that want play video games and casino games like us back in the days The game is continually in work in progress, the main goal is to add many games inside the game. Definition of PCB in Science & Medicine. The History of PCBs 1865-2001. PCB-AHA Conference Program, August 2-4, 2018 American History Does Not Begin with Jamestown and Plymouth: America and the Pacific since 1542 David Ringrose. On these pages, read about the vision of the six printed circuit board manufacturers that came together to create the Institute of Printed Circuits in the fall of 1957. Find events hosted by local groups where you can meet new people, try something new, or just do more of what you love. PCB is an acronym for printed circuit board. First, it holds all of the electrical components of an electronic system. More of this tension was noticeable in the Southern parts of the United States. : in a diagonal or oblique position. In 1995 we saw the first use of micro-via technology in PCB production, introducing the era of High Density Interconnect (HDI) PCBs. Please see our PCB Materials section for more information on the range of materials that MLT is capable of processing or give us a call if you want to discuss a particular application. PCB was first written by Thomas Nau for an Atari ST in 1990 and ported to UNIX and X11 in 1994. What might seem like an incredibly boring time in Internet history, as there were not many people on the internet in 1971, Michael Hart turned into an incredible opportunity. This category is for the history of the PCB servers themselves. In the 25 year history we have expanded from a local Singaporean Engineering Company serving the manufacturers based in Singapore to delivering complex systems globally to the Fortune 500 OEMs and CEMs. A phenyl ring is a ring of 6 carbon atoms to which hydrogen atoms are attached. Catto's Legacy and America's Civil Rights History IHA is pleased to announce the new educational portal dedicated to Civil Rights pioneer Octavius V Catto. Including EPA Methods 600/4-81-045 for oils; 608 for waste water and 1668 and 8082 for solid, and aqueous samples such as sediment and tissue. The production process was divided into departments identified with two-digit codes. DDT was one of the first chemicals in widespread use as a pesticide. Marking and Labeling PCBs • w-hw 4. The Audio Circuit is set up in 1996 with as goal to provide a free database on hifi, including user reviews, information, pictures, manuals and a forum. Looking back at the history of PCB design and manufacturing, it is clear that the PCB world has continuously evolved. sued Data East Corp. Litten presents a history of the the rise and fall of PCB usage in industrial processes, beginning with their arrival to the marketplace in 1929. Food and Drug Administration establishes a tolerance level of 5. We are committed to great customer service and excellence in high-quality design and development solutions. One of the most revolutionary technological inventions of all time is the Printed Circuit board technology. Packaging should be the same as what is found in a retail store, unless the item is handmade or was packaged by the manufacturer in non-retail packaging, such as an unprinted box or plastic bag. Based on the studies, DNR determined 3 priority areas for addressing the sediments within the impoundment. The day and the week are easily recognized and recorded - though an accurate calendar for the year is hard to achieve. The Grimsby & Cleethorpes History Club, Great Grimsby, North East Lincolnshire, United Kingdom. In short, FCT verifies a PCB’s functionality and its behavior. Whether you're a student or professional, SPICE will allow you to predict the behavior of your electronic circuits accurately. SPICE simulation is here! Autodesk EAGLE 8. PCBs were discovered during the 19th century. For many people today, PCBs are an integral part of life. What is RoHS? RoHS stands for Restriction of Hazardous Substances. PCB is dedicated to public protection by establishing and monitoring certification standards and examination development for professionals in the behavioral and community health fields in addition to providing management and consultation services. The programs handle Schematic Capture, and PCB Layout with Gerber output. Its unique, patented technologies can reduce design cycles by 50 percent or more while significantly improving overall quality and resource efficiency. But according to Nicholas Rogers, a history professor at York University in Toronto and author of "Halloween: From Pagan Ritual to Party Night" (Oxford University Press, 2003), "there is no hard. The Environmental Protection Division (EPD) of the Georgia Department of Natural Resources is a state agency charged with protecting Georgia's air, land, and. A history of PCB signal integrity – One man’s perspective, part 2 Douglas Brooks - December 15, 2014 Continued from Part 1 Stage 3: Resistance as a function of Frequency: Most of us have understood that resistance is constant with frequency. The Forged PCB Tours are not to be confused with the regular Forged PCB irons which are aimed more towards mid- to high handicappers. Navarro Central Appraisal District is responsible for appraising all real and business personal property within Navarro County. Flexible printed circuits were originally designed as a replacement for traditional wire harnesses. It has gone through a long and tortuous history. The Connecticut Department of Energy and Environmental Protection (CT DEEP) was initially awarded an EPA grant in 1981, to enforce polychlorinated biphenyl (PCB) regulations promulgated by the Environmental Protection Agency (EPA). Before the advent of the PCB circuits were constructed through a laborious process of point-to-point wiring. Chemists started playing around with these chemicals, to see if something useful could be made. We provide services that impact more than 840,000 students on 1,220 campuses in over 8 counties in North Texas. GeoChem Metrix Inc. It is titled, History of PCB 1938-1948. 03 the following changes have been implemented: Provision of a miniblade fuse for the Motors and heaters - Supplied with a 7. This chip is the mother of all PIC chips, functionally close to the current 16C54. Waste products and recycling operations. Cornelius as one of three vice-Presidents. Hampoo was founded in 2003, who is committed to being a leading one-stop hardware solution service provider. In 1990 the printed circuit board assets of Marquette Medical Systems, Inc were purchased and moved to Oshkosh, WI and reincorporated as Multicircuits, Inc. Jones Page 3 of 25 3 Introduction You've designed your circuit, perhaps even bread boarded a working prototype, and now it's time to turn it into a nice Printed Circuit Board (PCB) design. All I ask is that it be distributed in the original PDF form. Shield and PCB || It's All About History Fanfiction. Using the 2001-2004 data, the differences between mean PCB concentrations for women with and without a history of breastfeeding were not statistically significant for all age ranges, but higher mean concentrations were consistently observed in women with no history of breastfeeding. pcb Fabrication of the Printed Wiring Board - A Brief History:. Arizona Feb. History must be read with one eye on the religious principles and values which God has revealed and continues to reveal, and the other on concrete events. History - of - Religion How has the geography of religion evolved over the centuries, and where has it sparked wars? Our map gives us a brief history of the world's most well-known religions: Christianity, Islam, Hinduism, Buddhism, and Judaism. Here is a short list of the formats, their origins and current status. PCB contamination is high in the Housatonic River and New Bedford Harbor in Massachusetts. In the summer of 1978, a trucking company began to discreetly dump liquid contaminated with PCBs (polychlorinated biphenyls) along 240 miles of roads in 14 rural North. The copperplate is first coated with an acid-resistant substance, called the etching ground, through which the design is drawn with a sharp tool. A repair wire layer is provided within the PCB stack with reference planes on opposite sides of the repair wire layer. Cortland Street, Chicago, Illinois 60635, USA in the late 1970's and early 1980's. It is a board that has lines and pads that connect various points together. Every character has his ending sequence and his own stage. Keyword: printed circuit board, history of PCB. October 2012. Rubber Keypad; Keypad Assembly; Membrane Control Panel; Silicone Rubber Keypad; Backlight. Recognized internationally for PCB manufacturing. In an odd sense, PCBs and their manufacturing advancements has been a response to history itself - The product innovations of the roaring 1920s, the foundation for communication equipment during the 2nd World War and beyond, the backbone for the innovations brought on by the inventions of the transistor and the IC, and the "right stuff" for the electronics needed for landing a man on the moon. “Laser soldering method & theory” An advancing and developing next-generation soldering method – Laser soldering, the newest soldering method, now gaining the world’s attention – “Laser soldering is garnering attention as a new method. A versatile model capable of a wide variety of processing including automotive PCB, high frequency substrate, and back drilling Download. By Rick Campbell, KK7B A Binaural I-Q Receiver 1Notes appear on page 48. He described flat foil. A history of the Big Muff, from the Foxey Lady, to the Russian Sovteks, to the current USA re-issue. Workplace concentrations of PCBs, such as those in areas where PCB transformers are repaired and. General Instruments produced a chip called the PIC1650, described as a Programmable Intelligent Computer. The focus of their technical efforts was primarily on the development and application of integrated circuit technology to piezoelectric sensors. Attitudes Toward Work During the Classical Period 3. Remedial design/remedial action (RD/RA) consent decree between the United States, Pharmacia Corp. Please consider liking our page to help us share the history and culture of Wales with a. How Did We Get Here? The key inventions and techniques throughout the last 70 years that make the industry what it is to. sued Data East Corp. Learn about the complete history of EDA design automation and the evolution of PCB autorouting technology from the 1980s to today. The history of Bay County Bay County was established from Washington County in 1913 and named for St. Cairn University enjoys a heritage that spans over one hundred years. This risk is higher in a company without a history of growth. The illustrious history of the PCB Posted on March 1, 2016 March 1, 2016 by Stranco While printed circuit boards are an integral component of modern electronics today, their origin began in the early 20th century. In May of 1987, the Michigan Department of Transportation issued a report detailing the background of the Zilwaukee Bridge, the details on the accident and the attendant repairs as well as a discussion of the safety of the bridge, which was a major concern with the public at the time. Transistors had become commonplace in everything from radios to phones to computers, and now. Workplace concentrations of PCBs, such as those in areas where PCB transformers are repaired and. Pittsburgh Ballet Theatre. A load of an electrical circuit may be as simple as those that power home appliances like refrigerators , televisions, or lamps or more complicated, such as the load on the. Despite the low concentrations, PCB bioaccumulation in biota could potentially produce chronic effects, such as developmental effects, reproductive failure, liver damage, cancer, wasting syndrome, and death. May 3rd, 2019 saw the release of the Report on the Impact Study on Credit Reporting in Cambodia produced by Neil Munroe, Principal Consultant of CRS Insights Limited, an independent consultancy firm specializing in Credit Reporting. Time, a central theme in modern life, has for most of human history been thought of in very imprecise terms. He described the PCB as flat with foil conductors laminated to an insulating board in multiple layers. There is no charge and no time limit for this evaluation copy. Library service for Panama City Beach started in the 1960's with weekly bookmobile runs from the Bay County Public Library in Panama City. Recently found in a randomly filed box of dusty assorted papers in the basement of The Hall is the following account. The only thing that has changed is that now the company is able to ensure that virtually every person on the planet is affected by its toxic chemicals, via food. The original technology used very low frequencies and high power densities (the amount of electronic energy used to cavitate the ultrasonic wash bath – measured in. Microvia hole diameters are limited by aspect ratio (hole depth to hole diameter). Historical Context of the Work Ethic 2. One such invention was a primitive circuit board, a precursor to the first. The Pakistan Cricket Board was inaugurated on 1 May 1949 as the Board of Control for Cricket in Pakistan (BCCP). It's less known for being a toxic waterway that turned fish into mutants. Get latest sports news and updates from Cricket, Tennis, Football, Formula One, Hockey, NBA and Golf with Live scores. Their use was largely abandoned because they were either too ineffective or too toxic. How Did We Get Here? The key inventions and techniques throughout the last 70 years that make the industry what it is to. Many people are never more than a few feet away from a PCB - the TV, the microwave, the computer, the car, the smartphone… and the list goes on. Albert Hanson Comes Up With an Early Circuit Board. Attitudes Toward Work During the Medieval Period 4. By adding powerful circuit simulation and analyses to the design flow, Multisim™ helps researchers and designers reduce printed circuit board (PCB) prototype iterations and save development costs. A phenyl ring is a ring of 6 carbon atoms to which hydrogen atoms are attached. In 2016, Altium acquired Perception Software, a provider of enterprise PLM integration solutions. The Printed Circuit Board: Its Long Journey and History.


Laptops have become widely used due to their power and portability. There is still a price premium when comparing feature for feature with an equivalent laptop, but it is offset by the convenience offered by laptops. All laptops and portable systems offer the ability to run on battery power. The run times vary widely from model to model. The battery technology has changed also over the years, going from Nickel Cadmium to Nickel Metal Hydride, to Lithium Ion. Each type of battery has different requirements in care, but there are things you can do to extend the length of time you can run on a single charge.


A list of the 7 libraries in the architecture espressif32.
|Algoduino||A simple API client implementation in C++ for the Algorand Blockchain.|
|ESP-FlexyStepper||This library is used to control one or more stepper motors from an ESP32 device|
|ESP-StepperMotor-Server||A stepper motor control server for ESP32 with Web UI, REST API and CLI|
|esp32FOTA||A simple library for firmware OTA updates|
|JeVe_EasyOTA||Easy include OTA Updates|
|Mcp3208||Arduino library for the MCP320x 12 bit ADC family.|
|THiNX32||A library to wrap THiNX device registration, MQTT and OTA Update|


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At SWITZERLAND INNOVATION, interdisciplinary collaboration between science and industry flourish, enabling to find keys and pathways to commercialization of innovative products and services. Together with the Swiss Business Hub China and the Science, Technology and Education Section of the Embassy of Switzerland in China, SWITZERLAND INNOVATION and China Academy of Information and Communications Technology (CAICT) are committed to promoting Sino-Swiss R&D and innovation. SWITZERLAND INNOVATION provides a platform for corporate R&D teams to collaborate with leading scientists of world-leading universities, among them are the prestigious Swiss Federal Institutes of Technology Lausanne (EPFL) and Swiss Federal Institute of Technology Zurich (ETH Zurich). It provides companies the opportunity to directly access first-class R&D capacities in Switzerland. A scientific research institute under Ministry of Industry and Information Technology, CAICT contributes to strategy and sectoral policy making, such as Internet+, China Manufacturing 2025 and Broadband China. CAICT has performed in-depth studies and promoted cross-sectoral collaboration in the area of smart manufacturing and AI.
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3D printing gives clients a true sense of the finished product in this marriage of fashion and technology
A recent analysis by ResearchMoz, as quoted by Geektime, predicts that, “The global Wearable Technology Market…is expected to reach USD 5.8 billion in 2018…” To keep up with this rapidly growing field, wearable technology designers are looking to 3D printing to complement their R&D process. The ability of a designer to show a client a tangible prototype is especially valuable for wearable tech. When something is worn, the weight, texture and feel of the product are keys to its success.
Recently, the design consultancy firm zero360 worked with Industrial Plastic Fabrications Ltd (IPF) to prototype a wristband that senses the wearer’s “biosigns,” such as heart rate. The prototype was 3D printed on an Objet500 Connex3 Color Multi-material 3D Printer by Stratasys, allowing the designers to choose from 10 color palettes, each of which can be mixed to produce 46 different colors.
In a recent interview with TCT Magazine, Luke Guttery, Director of Product Design at zero360, said: “Comfort is a really important factor in sustained engagement, so being able to rapid prototype these is a key part of the development process. Also, the Objet Connex’ flexible material is very durable and is as good as casting, which is a massive plus, as it’s quicker to produce.”
According to Gary Miller of IPF, a UK based service bureau, it takes just a few hours to 3D print one of zero360’s wristbands. Using the Objet500 Connex3 Color Multi-material 3D Printer, a single print run can include 46 colors and multiple materials, allowing for different multi-material design variations to be prototyped at once.
In addition to saving time, 3D printing the prototype is cost effective. Guttery estimates the cost of creating the prototype using 3D printing is 85% less than conventional casting methods.
With the fashion and technology industries overlapping in the field of wearable tech, we expect to see more companies using 3D printing to give their clients a true sense of the finished product.
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Modbus Device Directory. The Modbus Organization maintains a database of Modbus devices as a service to users looking for such devices for their applications….
The range of data bytes in Modbus RTU can be any characters from 00 to FF. The range of data bytes in Modbus ASCII represent only the 16 hexadecimal characters….
Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase ……
Mar 27, 2012 · Actually i am not using Modbus.dll ; better u can make your own dll or a program that communicates with PLC, There is one more thing how u will process the ……
MODBUS® Protocol is a messaging structure developed by Modicon in 1979, used to establish master-slave/client-server communication between intelligent devices….
I need read 30000 register type from modbus slave. The configuration is: CPU Quantum, from Ethernet 140NOE77101 to TSX ETG 100 ethernet-modbus, slave modbus….
Download source files – 37.5 KB; Introduction. Often in my day I find myself testing and debugging devices that communicate via the modbus protocol….


Magnetron molybdenum sputtering target purity is 99.95% and density is 10.2g/cm3. The melting point of it is 2610℃ and boiling point is 5560℃.
Magnetron molybdenum sputtering target has a lot of advantages such as high strength, high temperature resistance, wear resistance, corrosion resistance and other advantages.
The types of it include rectangle magnetron molybdenum sputtering target, rotatable magnetron molybdenum sputtering target and cylindrical magnetron tube molybdenum sputtering target.
The operating principle of magnetron molybdenum sputtering target is that electron affected by electric field so the electron in the process of flying to substrate will crash with argon ion to produce new ion. Then the new ion fly to substrate but due to affected by electric field so argon ion fly to cathode target and hit surface of target with high strength to make target sputtering.
It is widely used in two-dimensional display, thin-film solar cells, wiring material and barrier material of semiconductor.


Through its broad product portfolio, ZF has the opportunity to offer intelligent, integrated system solutions. These can be turnkey based on which a wide variety of mobility solutions can be implemented – from electric compact cars to autonomous delivery vehicles. Manufacturers essentially need only the car body/bodyshell, the battery system and the interior to put their vehicles on four wheels.
An electric drive system with an output of up to 150 kW provides propulsion that is locally emission-free. The compact drive unit is a combination of the electric motor, a two-stage transmission, a differential and the power electronics. It saves space through its location in the mSTARS modular axle system. This makes the electrification of vehicle platforms in volume production particularly simple and flexible.
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The platform can also provide the necessary sensors, a central control unit and all interfaces for advanced assistance systems ranging from highly automated to autonomous driving functions.