Validation of Electroencephalographic Recordings Obtained with a Consumer-Grade, Single Dry Electrode, Low-Cost Device: A Comparative Study

The functional validity of the signal obtained with low-cost electroencephalography (EEG) devices is still under debate. Here, we have conducted an in-depth comparison of the EEG-recordings obtained with a medical-grade golden-cup electrodes ambulatory device, the SOMNOwatch + EEG-6, vs those obtained with a consumer-grade, single dry electrode low-cost device, the NeuroSky MindWave, one of the most a ordable devices currently available. We recorded EEG signals at Fp1 using the two di erent devices simultaneously on 21 participants who underwent two experimental phases: a 12-minute resting state task (alternating two cycles of closed/open eyes periods), followed by 60-minute virtual-driving task. We evaluated the EEG recording quality by comparing the similarity between the temporal data series, their spectra, their signal-to-noise ratio, the reliability of EEG measurements (comparing the closed eyes periods), as well as their blink detection rate. We found substantial agreement between signals: whereas, qualitatively, the NeuroSky MindWave presented higher levels of noise and a biphasic shape of blinks, the similarity metric indicated that signals from both recording devices were significantly correlated. While the NeuroSky MindWave was less reliable, both devices had a similar blink detection rate. Overall, the NeuroSky MindWave is noise-limited, but provides stable recordings even through long periods of time. Furthermore, its data would be of adequate quality compared to that of conventional wet electrode EEG devices, except for a potential calibration error and spectral differences at low frequencies.Spanish Department of Transportation, Madrid, Spain (Grant No. SPIP2014-1426 to L.L.D.S.)A.C. is funded by a Spanish Ministry of Economy and Competitiveness grant (PSI2016-80558-R to A.C.)S.R. is funded by an Andalusian Government Excellence Research grant (P11-TIC-7983)L.J.F. is funded by a Spanish Ministry of Economy and Competitiveness grant (PSI2014-53427-P) and a Fundación Séneca grant (19267/PI/14)L.L.D.S. is currently supported by the Ramón y Cajal fellowship program (RYC-2015-17483)C.D.-P. is currently supported by the CEIMAR program (CEIMAR2018-2)C.D.-P. and L.L.D.S. are supported by a Santander Bank—CEMIX UGR-MADOC grant (Project PINS 2018-15

Estudo da visión temporal e a regulación do fluxo sanguíneo

We will study the bases of visual perception associated to temporal factors, specifically stimulus duration and interstimulus intervals. We will use psychophysical and electrophysiological techniques to determine the effect of stimulus duration in the subjective perception of brightness and contrast, and also the neuronal basis of the phenomenon known as flicker fusion, in which a series of images presented in quick sequence are perceived as a single presentation. We will also study, using neuroimaging techniques, the brain blood flow changes evoked by this neuronal activity. Since epilepsy patients have their quality of life significantly impacted by temporal factors of visual stimulation, we will also study how blood flow alterations contribute to neural cell death in epilepsy.En este proyecto estudiaremos las bases de la percepción visual ligada a factores temporales, específicamente la duración del estímulo y el intervalo entre estímulos. Usando técnicas psicofísicas y electrofisiológicas, determinaremos el efecto de la duración de un estímulo en la percepción subjetivo de la luminosidad, y las bases neuronales del fenómeno conocido como fusión del parpadeo, en el que sucesivos estímulos presentados en rápida secuencia se perciben como una única presentación. También estudiaremos, empleando técnicas de neuroimagen, como la actividad neuronal generada puede provocar cambios en el flujo sanguíneo cerebral, y como estas alteraciones vasculares contribuyen a la muerte celular en epilepsia, una enfermedad en la que la calidad de vida de los pacientes se ve significativamente afectada por los factores temporales de la estimulación visual.Neste proxecto estudaremo-las bases da percepción visual ligada a factores temporais, específicamente a duración dos estímulo e o intervalo entre diferentes repeticións deste. Usando técnicas psicofísicas e electrofixiolóxicas, determinaremo-lo efecto da duración dun estímulo na percepción subxectiva da luminosidade e as bases neuronais do fenómeno conocido como fusión do parpadeo, no que sucesivos estímulos presentados en rápida sucesión son perceibidos coma unha única presentación. Tamén estudaremos, empregando técnicas de neuroimaxe, como a actividade neuronal xerada pode provocar cambios no fluxo sanguíneo cerebral, e como estas alteracións vasculares contribúen á morte celular en epilepsia, una enfermedade na que a calidade de vida dos pacientes vése significativamente afectada polos factores temporales da estimulación visual

Building a US company to manufacture solar PV mounting systems

This paper describes the process of developing a product for the solar industry. It is the story of starting a business in the solar market by designing a product, manufacturing the product and growing sales to over $1 million USD in 2011 and 2012. The author is describing the actual details of a manufacturing company that produces solar racking systems in the USA. The author founded the company in 2009 and left the company at the end of 2012. The document describes the changing landscape of the racking sector of the US PV market, and makes the case for industry standards in solar module dimensions. The range of current sizes of solar modules is described. The inconsistency in sizes creates additional overhead for manufacturers to accommodate different sized parts to hold the different solar panels. A uniform standard size would result in cost reductions for the end customers

Examples of primate SWJs.

<p>Each trace represents 3 seconds of horizontal (top) and vertical (bottom) eye position recordings containing SWJs. Primarily horizontal (left), vertical (middle), and oblique (right) SWJs are displayed. All time scales are as in the bottom trace.</p

Peak velocity-magnitude relationship for SWJ saccades and non-SWJ saccades.

<p>Main panel: Each dot represents a saccade with the peak velocity indicated on the y-axis and the magnitude on the x-axis. Color determines whether the saccade was part of a SWJ (red) or not (blue). Bottom panel: Average saccade magnitude distribution across monkeys (<i>n</i> = 5). Left panel: Average peak velocity distribution across monkeys (<i>n</i> = 5). Saccade magnitude and peak velocity were greater for SWJ saccades than for non-SWJ saccades (Z-values = 2.02; <i>p</i>-values = 0.04). The slopes of the peak velocity-magnitude relationships for SWJ saccades and non-SWJ did not differ statistically (Z-value = 0.14; <i>p</i> = 0.89).</p

Relationship between fixation error and Intra-SWJ ISI.

<p>A) The larger the distance to fixation target, the shorter the intra-SWJ ISI [Friedman's test (5, 9) = 17.55; <i>p</i> = 0.047)]. B) Likewise, larger saccades tend to be more quickly followed by return saccades [Friedman's test (5, 9) = 18.80; <i>p</i> = 0.026)]. Shadows indicate the s.e.m. across monkeys (<i>n</i> = 5).</p

Relationship between fixation error and subsequent SWJ generation.

<p><b>A) Schematic illustration of a fixation error.</b> The fixation target location, the magnitude of the first saccade in the SWJ, and the distance to the fixation target after the first SWJ saccade are indicated. Relationship between a saccade’s likelihood of being part of a SWJ and <b>B) the post-saccadic distance to the fixation target and C) the saccade’s magnitude.</b> Both relationships follow a logistic regression (<i>p</i>-values < 0.05), where a saccade’s likelihood of being part of a SWJ increases with both the distance to the fixation target after the saccade [Friedman's test (5, 4) = 12.32; <i>p</i> = 0.015] and the saccadic magnitude [Friedman's test (5, 4) = 16.64; <i>p</i> = 0.002)] up to 1 deg, and then plateaus for values > 1 deg [<i>p</i>-values >0.9]. Grey shadows indicate the s.e.m. across monkeys (<i>n</i> = 5).</p