Series Of Flashes Research Articles

The Impact of Single Group Flashes on Geostationary Lightning Mapper Data

AbstractThe Geostationary Lightning Mapper (GLM) is an instrument on the NOAA Geostationary Operational Environmental Satellites‐R (GOES‐R) Series. The GLM data are processed by the Lightning Cluster Filter Algorithm which filters the GLM data and clusters it into a series of events, groups, and flashes. One of the current filters in the GLM algorithm (as of June 2023) removes all flashes that have only a single group. Combining the flashes (including the flashes with only single group) from two of the GLMs (the GLM on GOES‐16 and the GLM on GOES‐17) in the region where they overlap produces a unique data set of coincident flashes (detected by both GLMs) and non‐coincident flashes (detected by only one GLM). Coincident flashes detected by both GLMs are very unlikely to be from noise sources. This data set allows us to estimate the impact of the single group flashes on the Detection Efficiency (DE) and the False Alarm Rate (FAR). We find that the single group flash filter does greatly improve the FAR but does slightly decrease the DE. Subsequent analysis shows that some of the removed flashes with single groups are from true lightning. A simple modification to the single group flash filter to only remove flashes with a single event increases the FAR without a corresponding improvement in DE. A more complex algorithm is needed to recover the single group flashes that are likely from lightning without adding back single group flashes that are from noise sources.

Observational appearance of a freely-falling star in an asymmetric thin-shell wormhole

It has been recently reported that, at late times, the total luminosity of a star freely falling in black holes decays exponentially with time, and one or two series of flashes with decreasing intensity are seen by a specific observer, depending on the number of photon spheres. In this paper, we examine observational appearances of an infalling star in a reflection-asymmetric wormhole, which has two photon spheres, one on each side of the wormhole. We find that the late-time total luminosity measured by distant observers gradually decays with time or remains roughly constant due to the absence of the event horizon. Moreover, a specific observer would detect a couple of light flashes in a bright background at late times. These observations would offer a new tool to distinguish wormholes from black holes, even those with multiple photon spheres.

Appearance of an infalling star in black holes with multiple photon spheres

Photon spheres play a pivotal role in the imaging of luminous objects near black holes. In this paper, we examine observational appearances of a star freely falling in hairy black holes, which can possess one or two photon spheres outside the event horizon. When there exists a single photon sphere, the total luminosity measured by distant observers decreases exponentially with time at late times. Due to successive arrivals of photons orbiting around the photon sphere different times, a specific observer would see a series of light flashes with decreasing intensity, which share a similar frequency content. Whereas in the case with two photon spheres, photons temporarily trapped between the photon spheres can cause a peak of the total luminosity, which is followed by a slow exponential decay, at late times. In addition, these photons lead to one more series of light flashes seen by the specific observer.

Superior visual rhythm discrimination in expert musicians is most likely not related to cross-modal recruitment of the auditory cortex.

Training can influence behavioral performance and lead to brain reorganization. In particular, training in one modality, for example, auditory, can improve performance in another modality, for example, visual. Previous research suggests that one of the mechanisms behind this phenomenon could be the cross-modal recruitment of the sensory areas, for example, the auditory cortex. Studying expert musicians offers a chance to explore this process. Rhythm is an aspect of music that can be presented in various modalities. We designed an fMRI experiment in which professional pianists and non-musicians discriminated between two sequences of rhythms presented auditorily (series of sounds) or visually (series of flashes). Behavioral results showed that musicians performed in both visual and auditory rhythmic tasks better than non-musicians. We found no significant between-group differences in fMRI activations within the auditory cortex. However, we observed that musicians had increased activation in the right Inferior Parietal Lobe when compared to non-musicians. We conclude that the musicians' superior visual rhythm discrimination is not related to cross-modal recruitment of the auditory cortex; instead, it could be related to activation in higher-level, multimodal areas in the cortex.

Digigram by Barbara Henning

Reviewed by: Digigram by Barbara Henning Kit Robinson (bio) digigram Barbara Henning United Artist Books https://www.spdbooks.org/Products/9780935992502/digigram.aspx 92 Pages; Print, $16.00 For a long time, the poet, novelist, and teacher Barbara Henning has made a career of violating genre boundaries, mixing fact and fiction, prose and poetry, autobiography and chance procedure to compile an utterly original body of work. Written in the pre-COVID teens during the hellish rise of Ubu Trump, her new book, Digigram, is an homage to public life, a celebration of the energy, movement, community, anonymity, and freedom afforded by our erstwhile urban existence. At the same time, through memory, dream, and reflection, Henning opens the door to her private world, a realm of love, joy, sorrow, and deep, if fraught, relationship. Digigram is a sequence of prose poems titled and dated from 25 February 2016 to 24 April 2018. Each entry is a verbal construct of phrases recording the events of one day through a series of flashes. Henning's use of the em dash to link the phrases frees her from the constraints of standard syntax and creates an equivalency across disparate referents—public and private, personal and political, past and present, dreaming and waking life. We join her on her bike, in cabs, on the subway, and in apartments and restaurants while she makes her way around the New York City of her continuous present, as well as the Detroit of her youth. Interspersed among her daily observations and encounters, news items appear like a running subtext injected into the flow. Trump, a looming, ominous presence throughout, is named only as "the bully." Strains of racism, oligarchy, and corruption interlace with verbal snapshots of quotidian events. As inner and outer worlds collide, feelings of anxiety, tenderness, and outrage animate the narrative. Two aspects of city life permeate the text: simultaneity and coincidence. One has the overwhelming sense of innumerable things going on at once. Street scenes commingle with states of mind in a kaleidoscopic mélange navigable [End Page 135] only by a quick-witted, intuitive narrator. Coincidence, a natural by-product of complexity, arrives early and often, as identical structures of feeling coincide: —an old female orangutan—locks eyes—with a young woman—breastfeeding a baby—yes, she nods, me, too–("Me, Too") Henning often uses words as hinges to swing from one realm of consciousness to the next and back again. In "Let Me Know," the narrative shifts from a bike ride by the shore of Lake Superior to immigration law to a soccer match to electoral politics. Each shift is triggered by the word or concept "pass": —as I pass the woman on the bike … many mothers are unable to pass on—their citizenship … when a pass is made—four defenders charge … a committee of American men—will meet to decide—the rights of women ("Let Me Know") The em dashes remind one of William Burroughs, but with an important difference: Henning's work is proudly feminist. The poems act as both argument and anthem: —the outlook for 2016 somewhat gloomy … a NYC policeman forces a man to stand—outside—in his underwear … another bully wants—to be liked by the alpha bully … ugly and frightful haters, bashers, hucksters—he-who-must-not-be-named … tear gas fired at children … 14,000 Syrian migrants—in desperate condition ("Wham!") "River God" begins with a description of the book's cover image, a 1984 photograph of the author's young children posing on the "belly of a river god," a statue at the Detroit Institute of Art, "looking over a baby angel—then over—the ruins of Detroit." The poem ends with "the boys reclining—beside my grown daughter—watching TV—feet overlapping." Past and present cohabit in Henning's kaleidoscopic prosody, which morphs and spreads in all directions, only to execute a poignant return: —at night—a cold-air bath—thunder—the sound of rain on the pavement—turn off the lights—lie in bed—in the dark—and [End Page 136] listen—my arms crossed—over my bare chest—the child I was—am now—Mama and Daddy—I say out loud—("A...

Measurement of electroretinogram responses in OPA1‐associated autosomal dominant optic atrophy using a handheld device

AbstractPurposeAutosomal dominant optic atrophy (ADOA) associated with OPA1 variants is the most common inherited optic neuropathy in the population. The utility of the Ganzfeld electroretinogram (ERG) in evaluating ADOA has not been extensively investigated. In this study, we explored the potential of using a handheld ERG device (RETeval®) to measure ERG responses in a cohort of patients with ADOA carrying pathogenic OPA1 mutations.MethodsThe Ganzfeld photopic ERG was recorded in 15 individuals with OPA1‐associated ADOA in response to series of flashes (200, automatically adjusted in intensity to pupil diameter) using the RETeval® handheld ERG device and skin electrodes. Two to three series were obtained from each eye. The recordings were analysed for noise and drift manually. Both visual acuity measurements, and optical coherence tomography ganglion cell layer (GCL) and retina nerve fibre layer (RNFL) thicknesses were recorded to explore correlation with ERG parameters.ResultsThere was a significant correlation between LogMAR visual acuity and both the a‐wave (ρ = ‐0.60, p = 0.02, n = 15) and b‐wave (ρ = ‐0.54, p = 0.04, n = 15) peak times. As a‐wave and b‐wave peak time correlated with age, a multiple linear regression analysis was performed to exclude age as a confounder. With respect to the a‐wave analysis, the coefficients for visual acuity and age were ‐0.66 (p = 0.019) and 0.015 (p = 0.14), respectively. With respect to b‐wave analysis, the coefficients for visual acuity and age were ‐1.32 (p = 0.017) and 0.028 (p = 0.16), respectively. There was no significant correlation between a‐wave and b‐wave peak times with the OCT structural parameters that were analysed.ConclusionsIn patients with OPA1‐associated ADOA, a‐wave and b‐wave peak times correlated negatively with LogMAR visual acuity, independent of the effects of age. The pathophysiological relevance of these findings requires further investigation in a larger patient cohort.

Diabetic mice have retinal and choroidal blood flow deficits and electroretinogram deficits with impaired responses to hypercapnia

PurposeThe purpose of this study was to investigate neuronal and vascular functional deficits in the retina and their association in a diabetic mouse model. We measured electroretinography (ERG) responses and choroidal and retinal blood flow (ChBF, RBF) with magnetic resonance imaging (MRI) in healthy and diabetic mice under basal conditions and under hypercapnic challenge.MethodsIns2Akita diabetic (Diab, n = 8) and age-matched, wild-type C57BL/6J mice (Ctrl, n = 8) were studied under room air and moderate hypercapnia (5% CO2). Dark-adapted ERG a-wave, b-wave, and oscillatory potentials (OPs) were measured for a series of flashes. Regional ChBF and RBF under air and hypercapnia were measured using MRI in the same mice.ResultsUnder room air, Diab mice had compromised ERG b-wave and OPs (e.g., b-wave amplitude was 422.2±10.7 μV in Diab vs. 600.1±13.9 μV in Ctrl, p < 0.001). Under hypercapnia, OPs and b-wave amplitudes were significantly reduced in Diab (OPs by 30.3±3.0% in Diab vs. -3.0±3.6% in Ctrl, b-wave by 17.9±1.4% in Diab vs. 1.3±0.5% in Ctrl). Both ChBF and RBF had significant differences in regional blood flow, with Diab mice having substantially lower blood flow in the nasal region (ChBF was 5.4±1.0 ml/g/min in Diab vs. 8.6±1.0 ml/g/min in Ctrl, RBF was 0.91±0.10 ml/g/min in Diab vs. 1.52±0.24 ml/g/min in Ctrl). Under hypercapnia, ChBF increased in both Ctrl and Diab without significant group difference (31±7% in Diab vs. 17±7% in Ctrl, p > 0.05), but an increase in RBF was not detected for either group.ConclusionsInner retinal neuronal function and both retinal and choroidal blood flow were impaired in Diab mice. Hypercapnia further compromised inner retinal neuronal function in diabetes, while the blood flow response was not affected, suggesting that the diabetic retina has difficulty adapting to metabolic challenges due to factors other than impaired blood flow regulation.

Lithium in red giants: the roles of the He-core flash and the luminosity bump

ABSTRACT Lithium abundances for red giants in the GALAH DR3 survey are studied. The rare examples of Li-enriched stars with abundances A(Li) ≥1.5 are confirmed to be He-core burning stars belonging to or evolved from the red clump with similar masses and metallicity: M ≃ 1.1 ± 0.2 M⊙ and [Fe/H] ≃ −0.3 ± 0.3. Li enrichment over the Li abundance present in a star’s predecessor at the tip of the red giant branch likely occurs in all these red clump stars. Examination of the elemental abundances (C to Eu) in the GALAH catalogue shows no anomalous abundances in red clump giants and, in particular, no dependence on the Li abundance, which ranges over at least five dex. Lithium synthesis is attributed to the He-core flash occurring in stars at the tip of the red giant branch. Models from the Modules for Experiments in Stellar Astrophysics (MESA) match the observed evolution of these stars along the red giant branch and to the red clump but only at the low effective temperature end of the observed spread of red clump giants. Run of Li abundance on the red giant branch is fairly well reproduced by MESA models. A speculation is presented that the series of He-core flashes not only leads to 7Li synthesis from a star’s internal reservoir of 3He but also may lead to internal restructuring leading to the observed effective temperature spread of red clump stars at about a constant luminosity. Giants exhibiting marked Li enrichments are not found at other evolutionary phases and, in particular, not directly associated with the luminosity bump on the red giant branch for which the Li abundance increase does not exceed 0.3 dex.

Research of combustion of flickering pyrotechnical products

The process of combustion of flickering pyrotechnic products containing metallic and non-metallic fuel was investigated. A research method based on the comparison of experimental and calculated data is proposed, which allows the creation of flickering pyrotechnic products with a given duration of the interval between flashes.Flickering pyrotechnic products, the burning of which is accompanied by a series of bright flashes, are used in the technique of fireworks to create original light paintings.According to the known works, the range of characteristics of such products is quite wide. In particular, the duration of the interval between flashes may range from hundredths of a second to several seconds. However, in literature there are no details of the reasons pulsating nature of combustion and quantitative characteristics of the processes that occur at the same time. Due to the lack of a theoretical base, pyrotechnic product developers have to go empirically, relying only on experimental experience. An unresolved scientific problem is the lack of a theoretical approach to the development of flickering pyrotechnic articles with a given duration of the interval between flashes.The purpose of the article is to obtain data on the quantitative characteristics of the processes occurring during the burning of flickering pyrotechnic articles, and to develop a methodology that will allow to create products whose combustion parameters - primarily the duration of the interval between flashes - would be predictable in advance.The pulsating character of the combustion is a consequence of the parallel course of processes having different time scales. There are at least two types of such processes: fast exothermic combustion reactions and slow heat loss to the environment. The speed of the latter, among other things, depends on the size of the heat transfer surface, which is determined by the diameter of the product, if it has the shape of a body of rotation. By varying the diameter obviously can affect the rate of heat transfer, and with it the nature of combustion. From this assumption follows the task of this study - to investigate the burning of flickering products of cylindrical shape, which differ only in diameter.The results were obtained by comparing experimental data on the duration of the interval between flashes with the data obtained in the calculated way.The temporal characteristics of the combustion of the samples were determined using a storage oscilloscope, to which a photocell was connected. The interval between flashes was determined by the screen scale as the distance between the peaks of the waveform.According to our observations, the following occurs in the process of sample burning. During ignition, non-metallic fuel - sulfur, is first lit. It lights up easily but burns slowly, warming the composition of the site to the ignition temperature of the metal fuel. The latter lights up harder but burns quickly with a flash.The sharp flash of metallic fuel is accompanied by spreading hot combustion products, because they are unable to ignite the next batch of metal. However, the sulfur continues to burn, so the cycle repeats. The duration of the interval between flashes is determined by the heating time of the sample portion of the burning sulfur to the ignition temperature of the metallic fuel.The study confirmed the assumption that to change the duration of the interval between flashes of flashing pyrotechnic products within certain limits, it is enough to change their diameter.

НЕЙРОФІЗІОЛОГІЧНІ МЕХАНІЗМИ ЛОГОНЕВРОЗУ У ДІТЕЙ ДОШКІЛЬНОГО ВІКУ ПРИ ФУНКЦІОНАЛЬНИХ НАВАНТАЖЕННЯХ

The changes in the electrical activity of the brain of boys with different tempo-rhythmic characteristics of speech during functional stress have been studied, namely, a series of flashes of light of a certain frequency – rhythmic photostimulation have been used. The bioelectrical activity of the brain has been studied using a computer electroencephalography system. Also, according to the methodology of zonal distribution of normalized spectral power (SP) of the rhythm of the main frequency of the EEGranges, the particles (in percent) of the normalized SP of electrogenesis in each of the four main ranges (δ, θ, α, β) have been determined. As a result of comparison of the light flashing frequency assimilation among boys in the studied groups, it has been found, that in the group of children with logoneurosis slow rhythms (5 Hz,) lying within the theta-range of the EEG, were better assimilated. The rhythm is assimilated in the low frequency range among the children with logoneurosis. The relative spectral power of theta-rhythm significantly decreased on the EEG of children with tempo and rhythm speech disorder at low-frequency photostimulation in comparison with the corresponding indicators of the background electroencephalogram; the corresponding indicators in the beta-range, anterior and posterior leads in the alpha-rangeincreased. Based on the obtained data, it has been found, that children with logoneurosis have insufficient response to photostimulation. Such data are associated with insufficient inhibitory effect of the cortex on the subcortical structures. The reduced reactivity and functional insufficiency of the activating system of the brain stem have been noted. Neurophysiological mechanisms of logoneurosis are due to the state of insufficient formation of brain structures, which is confirmed by the results of electroencephalography during rhythmic photostimulation. Changes in the tempo and rhythm of speech during logoneurosis of preschool children provoke stress of the brain mechanisms of regulation, which become apparent by special characteristics of the electrical activity of the brain, both at rest and during load.

Thermodynamic model of fast pyrolysis bio-oil advanced distillation curves

Fast pyrolysis bio-oil (FPBO) is a complex organic liquid with over 1000 organic compounds. Therefore, little research exists on the prediction and modelling of liquid physicochemical properties and vapour-liquid phase behaviour. A thermodynamic model of the FPBO vapour-liquid equilibrium (VLE) in distillation will improve the understanding of bulk and FPBO fraction properties, and therefore, aid in the enhancement of FPBO for desired applications, such as condensation of pyrolysis vapours, fractionation, and evaporation during combustion. FPBO produced at 450 °C from softwood sawmill residues at a feed rate of 4 kg/h (~20 s residence time) in a pilot-scale auger reactor was distilled in an advanced distillation curve (ADC) apparatus at atmospheric pressure and at a vacuum of 5 kPa (abs). The ADC equipment allows for the data collection of true thermodynamic state points, including vapour phase composition data. UNIQUAC was the selected equation of states (EoS) to model FPBO distillation VLEs in a 20–flash series in VMGSim™. A surrogate mixture of water, 3,4,4′-biphenoltriol (pyrolytic lignin), inert solids, and multiple organic components was used to model and predict the VLE and consequently bulk physicochemical properties. It was found that GC-FID composition data (in area%), water content (Karl Fisher titration), distillation residue, and solid content were sufficient to inform the model (surrogate composition). This work improved the understanding of FPBO phase behaviour, composition, and bulk properties. The method allows for the identification of target components and fractions to enhance FPBO quality for desired applications.

Redox transients of P680 associated with the incremental chlorophyll-a fluorescence yield rises elicited by a series of saturating flashes in diuron-treated photosystem II core complex of Thermosynechococcus vulcanus.

Recent chlorophyll-a fluorescence yield measurements, using single-turnover saturating flashes (STSFs), have revealed the involvement of a rate-limiting step in the reactions following the charge separation induced by the first flash. As also shown here, in diuron-inhibited PSII core complexes isolated from Thermosynechococcus vulcanus the fluorescence maximum could only be reached by a train of STSFs. In order to elucidate the origin of the fluorescence yield increments in STSF series, we performed transient absorption measurements at 819 nm, reflecting the photooxidation and re-reduction kinetics of the primary electron donor P680. Upon single flash excitation of the dark-adapted sample, the decay kinetics could be described with lifetimes of 17 ns (∼50%) and 167 ns (∼30%), and a longer-lived component (∼20%). This kinetics are attributed to re-reduction of P680•+ by the donor side of PSII. In contrast, upon second-flash (with Δt between 5 μs and 100 ms) or repetitive excitation, the 819 nm absorption changes decayed with lifetimes of about 2ns (∼60%) and 10ns (∼30%), attributed to recombination of the primary radical pair P680•+ Pheo•- , and a small longer-lived component (∼10%). These data confirm that only the first STSF is capable of generating stable charge separation-leading to the reduction of QA ; and thus, the fluorescence yield increments elicited by the consecutive flashes must have a different physical origin. Our double-flash experiments indicate that the rate-limiting steps, detected by chlorophyll-a fluorescence, are not correlated with the turnover of P680.

Eobard Thawne: A Study Case of Main Villains in the Flash Series Season 1

Every superhero needs a villain. The Flash is an American superhero television series developed by Greg Berlanti, Andrew Kreisberg, and Geoff Johns, airing on The CW. It is based on the DC Comics character Barry Allen / The Flash, a costumed superhero crime-fighter with the power to move at superhuman speeds. In The Flash TV series Season 1, Eobard Thawne is introduced as a scientist from the future; he duplicated the reaction behind Barry Allen/The Flash's powers and learned he would become his own hero's arch-enemy: the Reverse-Flash. This study is aimed to identify the methods of characterization used in introducing Eobard Thawne as the main villain, and also analyzing the intrinsic and extrinsic motivations that the main villain character develops. In collecting the data, this study used library research and the data itself was analyzed qualitatively. Finally, the methods of characterization of the main villain character as well as the character’s motivations are explained. The character may be seen as simple at first glance, but Eobard Thawne has the components that describe him as evil character; from his characterization in his introduction to the motivations that guide him through each step of the story. Indeed, it is absolute reverse.

Konceptualizacja wspomnień w polskim i rosyjskim przekładzie autobiografii Vladimira Nabokova Speak, memory. An Autobiography Revisited

The main aim of this article is to analyze the conceptualization of memories in Vladimir Nabokov’s memoir, Speak memory: An Autobiography Revisited and its Polish and Russian translations. The article uses the devices of cognitive linguistics. Nabokov’s text contains three types of conceptual metaphors based on visual effect: MEMORIES ARE A SERIES OF FLASHES, MEMORIES ARE PERSONAL GLIMMERS and TO RECOLLECT IS TO JOURNEY BACK. Such metaphorical images are conveyed in translations in which many semantic shifts and transformations occur.

Regional differences in the preferred e-vector orientation of honeybee ocellar photoreceptors

In addition to compound eyes, honeybees (Apis mellifera) possess three single-lens eyes called ocelli located on the top of the head. Ocelli are involved in head-attitude control and in some insects have been shown to provide celestial compass information. Anatomical and early electrophysiological studies have suggested that UV and blue-green photoreceptors in ocelli are polarization sensitive. However, their retinal distribution and receptor characteristics have not been documented. Here, we used intracellular electrophysiology to determine the relationship between the spectral and polarization sensitivity of the photoreceptors and their position within the visual field of the ocelli. We first determined a photoreceptor's spectral response through a series of monochromatic flashes (340-600 nm). We found UV and green receptors, with peak sensitivities at 360 and 500 nm, respectively. We subsequently measured polarization sensitivity at the photoreceptor's peak sensitivity wavelength by rotating a polarizer with monochromatic flashes. Polarization sensitivity (PS) values were significantly higher in UV receptors (3.8±1.5, N=61) than in green receptors (2.1±0.6, N=60). Interestingly, most receptors with receptive fields below 35deg elevation were sensitive to vertically polarized light while the receptors with visual fields above 35deg were sensitive to a wide range of polarization angles. These results agree well with anatomical measurements showing differences in rhabdom orientations between dorsal and ventral retinae. We discuss the functional significance of the distribution of polarization sensitivities across the visual field of ocelli by highlighting the information the ocelli are able to extract from the bee's visual environment.

Relative functional and optical absorption cross-sections of PSII and other photosynthetic parameters monitored in situ, at a distance with a time resolution of a few seconds, using a prototype light induced fluorescence transient (LIFT) device.

The prototype light-induced fluorescence transient (LIFT) instrument provides continuous, minimally intrusive, high time resolution (~2s) assessment of photosynthetic performance in terrestrial plants from up to 2m. It induces a chlorophyll fluorescence transient by a series of short flashes in a saturation sequence (180 ~1μs flashlets in <380μs) to achieve near-full reduction of the primary acceptor QA, followed by a relaxation sequence (RQA; 90 flashlets at exponentially increasing intervals over ~30ms) to observe kinetics of QA re-oxidation. When fitted by the fast repetition rate (FRR) model (Kolber et al. 1998) the QA flash of LIFT/FRR gives smaller values for FmQA from dark adapted leaves than FmPAM from pulse amplitude modulated (PAM) assays. The ratio FmQA/FmPAM resembles the ratio of fluorescence yield at the J/P phases of the classical O-J-I-P transient and we conclude that the difference simply is due to the levels of PQ pool reduction induced by the two techniques. In a strong PAM-analogous WL pulse in the dark monitored by the QA flash of LIFT/FRR φPSIIWL ≈ φPSIIPAM. The QA flash also tracks PQ pool reduction as well as the associated responses of ETR QA → PQ and PQ → PSI, the relative functional (σPSII) and optical absorption (aPSII) cross-sections of PSII in situ with a time resolution of ~2s as they relax after the pulse. It is impractical to deliver strong WL pulses at a distance in the field but a longer PQ flash from LIFT/FRR also achieves full reduction of PQ pool and delivers φPSIIPQ ≈ φPSIIPAM to obtain PAM-equivalent estimates of ETR and NPQ at a distance. In situ values of σPSII and aPSII from the QA flash with smaller antenna barley (chlorina-f2) and Arabidopsis mutants (asLhcb2-12, ch1-3 Lhcb5) are proportionally similar to those previously reported from in vitro assays. These direct measurements are further validated by changes in antenna size in response to growth irradiance. We illustrate how the QA flash facilitates our understanding of photosynthetic regulation during sun flecks in natural environments at a distance, with a time resolution of a few seconds.

Flicker Regularity Is Crucial for Entrainment of Alpha Oscillations.

Previous studies have shown that alpha oscillations (8–13 Hz) in human electroencephalogram (EEG) modulate perception via phase-dependent inhibition. If entrained to an external driving force, inhibition maxima and minima of the oscillation appear more distinct in time and make potential phase-dependent perception predictable. There is an ongoing debate about whether visual stimulation is suitable to entrain alpha oscillations. On the one hand, it has been argued that a series of light flashes results in transient event-related responses (ERPs) superimposed on the ongoing EEG. On the other hand, it has been demonstrated that alpha oscillations become entrained to a series of light flashes if they are presented at a certain temporal regularity. This raises the question under which circumstances a sequence of light flashes causes entrainment, i.e., whether an arrhythmic stream of light flashes would also result in entrainment. Here, we measured detection rates in response to visual targets at two opposing stimulation phases during rhythmic and arrhythmic light stimulation. We introduce a new measure called “behavioral modulation depth” to determine differences in perception. This measure is capable of correcting for inevitable artifacts that occur in visual detection tasks during visual stimulation. The physical concept of entrainment predicts that increased stimulation intensity should produce stronger entrainment. Thus, two experiments with medium (Experiment 1) and high (Experiment 2) stimulation intensity were performed. Data from the first experiment show that the behavioral modulation depth (alpha phase-dependent differences in detection threshold) increases with increasing entrainment of alpha oscillations. Furthermore, individual alpha phase delays of entrained alpha oscillations determine the behavioral modulation depth: the largest behavioral modulation depth can be found if targets presented during the minimum of the entrained oscillation are compared to those presented during the maximum. In the second experiment stimulation with higher light intensity during both rhythmic and arrhythmic stimulation lead to an increased behavioral modulation depth, supposedly as a consequence of stronger entrainment during rhythmic stimulation. Altogether, our results reveal evidence for rhythmic and arrhythmic visual stimulation to induce fundamentally different processes in the brain: we suggest that rhythmic but not arrhythmic stimulation interacts with ongoing alpha oscillations via entrainment.

Partial and complete methane oxidation in supercritical water

The paper represents results on investigation of methane oxidation in supercritical water (SCW) in autoclave and flow conditions. In the autoclave, oxidation is realized under uniform heating of a CH4/O2/H2O and CH4/O2/N2 mixture to 873 K (the water and nitrogen density ≈ 3.2 mmol/cm3, the molar ratio [O2]0/[CH4]0 ≈ 1 and 2). In the composition of the oxidation products we detected H2 (only at [O2]0/[CH4]0 ≈ 1), CO and CO2. Based on time dependences of the reaction mixture temperature we have found that temperature of the onset of self-heating of the CH4/O2/H2O mixture is lower by 23 K than that of the CH4/O2/N2 mixture and grows as the CH4 concentration decreases. For comparable values of self-heating the average power in CH4 combustion in the H2O medium has appeared to be about two orders lower than in the N2 medium, which evidences inhibition of SCWmethane oxidation. In the boiler-reactor, oxidation was realized while mixing CH4 and O2 in counter-propagating jets in the cocurrent upflow of SCW at 673–874 K, 30 MPa (molar ratio [O2]/[CH4] ≈ 2.2). Unsteady combustion was observed only at a reaction mixture temperature of 678 K, which became steady at 700 K after a series of flashes. The carbon-bearing methane oxidation products in the boiler-reactor contain only CO2 (≥ 97.5%) and CO (≤ 2.5%mole).

A shared numerical representation for action and perception.

Humans and other species have perceptual mechanisms dedicated to estimating approximate quantity: a sense of number. Here we show a clear interaction between self-produced actions and the perceived numerosity of subsequent visual stimuli. A short period of rapid finger-tapping (without sensory feedback) caused subjects to underestimate the number of visual stimuli presented near the tapping region; and a period of slow tapping caused overestimation. The distortions occurred both for stimuli presented sequentially (series of flashes) and simultaneously (clouds of dots); both for magnitude estimation and forced-choice comparison. The adaptation was spatially selective, primarily in external, real-world coordinates. Our results sit well with studies reporting links between perception and action, showing that vision and action share mechanisms that encode numbers: a generalized number sense, which estimates the number of self-generated as well as external events.

Age-related change in fast adaptation mechanisms measured with the scotopic full-field ERG

To quantify the response dynamics of fast adaptation mechanisms of the scotopic ERG in younger and older adults using full-field m-sequence flash stimulation. Scotopic ERGs were measured for a series of flashes separated by 65ms over a range of 260ms in 16 younger (20-26, 22.2±2.1; range mean ±1 SD) and 16 older (65-85, 71.2±7) observers without retinal pathology. A short-wavelength (λ peak=442nm) LED was used for scotopic stimulation, and the flashes ranged from 0.0001 to 0.01cdsm(-2). The complete binary kernel series was derived from the responses to the m-sequence flash stimulation, and the first- and second-order kernel responses were analyzed. The first-order kernel represented the response to a single, isolated flash, while the second-order kernels reflected the adapted flash responses that followed a single flash by one or more base intervals. B-wave amplitudes of the adapted flash responses were measured and plotted as a function of interstimulus interval to describe the recovery of the scotopic ERG. A linear function was fitted to the linear portion of the recovery curve, and the slope of the line was used to estimate the rate of fast adaptation recovery. The amplitudes of the isolated flash responses and rates of scotopic fast adaptation recovery were compared between the younger and older participants using a two-way ANOVA. The isolated flash responses and rates of recovery were found to be significantly lower in the older adults. However, there was no difference between the two age groups in response amplitude or recovery rate after correcting for age-related changes in the density of the ocular media. These results demonstrated that the rate of scotopic fast adaptation recovery of normal younger and older adults is similar when stimuli are equated for retinal illuminance.