Note: Active optical detection of cloud from a balloon platform

A disposable backscatter instrument is described for optical detection of cloud in the atmosphere from a balloon-carried platform. It uses an ultra-bright light emitting diode (LED) illumination source with a photodiode detector. Scattering of the LED light by cloud droplets generates a small optical signal which is separated from background light fluctuations using a lock-in technique. The signal to noise obtained permits cloud detection using the scattered LED light, even in daytime. The response is interpreted in terms of the equivalent visual range within the cloud. The device is lightweight (150 g) and low power (∼30 mA), for use alongside a conventional meteorological radiosonde.

Expressão de zif-268 durante a aquisição, evocação e extinção de uma memória aversiva

In the behavioral paradigm of discriminative avoidance task, both short and long-term memories have been extensively investigated with behavioral and pharmacological approaches. The aim of the present study was to evaluate, using the abovementioned model, the hippocampal expression of zif-268 - a calcium-dependent immediate early gene involved with synaptic plasticity process - throughout several steps of memory formation, such as acquisition, evocation and extiction. The behavioral apparatus consisted of a modified elevaated plus-maze, with their enclosed arms disposed in "L". A pre-exposure to the maze was made with the animal using all arms enclosed, for 30 minutes, followed by training and test, during 10 minutes each. The between sections interval was 24h. During training, aversive stimuli (bright light and loud noise) were actived whenever the animals entered one of the enclosed armas (aversive arm). Memory acquisiton, retention and extinction were evaluated by the percentage of the total time spent exploring the aversive arm. The parameters evaluated (time spent in the arms and total distance traveled) were estimated with an animal tracking software (Anymaze, Stoelting, USA). Learning during training was estimated by the decrease of the time spent exploring the aversive arm. One hour after the beginning of each section, animals were anaesthetized with sodium-thiopental (i.p.) and perfused with 0.9% heparinized saline solution followed by 4% paraformaldehyde. Brains were cryoprotected with 20% sucrose, separeted in three blocks and frozen. The middle block, containing the hippocampus, was sectioned at 20 micro meters in the coronal plane and the resutant sections were submitted to zif-268 immunohistochemistry. Our results show an increased expression of zif-268 in the dentate gyrus (DG) during the evocation and extinction stages. There is a distinct participation of the DG during the memory evocation, but not during its acquisition. Inaddition, all hippocampal regions (CA1, CA3 and DG) presented an increased zif-268 expression during the process of extinction.

Alterações na evocação de uma memória aversiva ao liongo do ciclo estral de ratas: influências da transmissão gabaérgica na amígdala

GABAergic neurotransmission has been implicated in many aspects of learning and memory, as well as mood and anxiety disorders. The amygdala has been one of the major focuses in this area, given its essential role in modulating emotionally relevant memories. However, studies with male subjects are still predominant in the field. Here we investigated the consequences for an aversive memory of enhancing or decreasing GABAergic transmission in the basolateral nucleus of the amygdala (BLA). Wistar female rats were trained in the plus-maze discriminative avoidance task, in which they had to learn to avoid one of the enclosed arms where an aversive stimulus consisting of a bright light and a loud noise was given (day 1). Fifteen minutes before the test session (day 2) animals received 0,2 μL infusions of either saline solution, the GABAergic agonist muscimol (0,05 mg/ml), or the GABAergic antagonist bicuculine (0,025 mg/ml) bilaterally intra-BLA. On the test day, females in proestrous or estrous presented adequate retrieval and did not extinguish the task, while females in metestrous or diestrous presented impaired retrieval. In the first group, muscimol infusion impaired retrieval and bicuculline had no effect, suggesting naturally low levels of GABAergic transmission in the BLA of proestrous and estrous females. In the second group, muscimol infusion had no effect and bicuculline reversed retrieval impairment, suggesting naturally high levels of GABAergic transmission in the BLA of metestrous and diestous females. Additionally, proestrous and estrous females presented higher anxiety levels compared to metestrous and diestrous females, which could explain better performance of this group. On the other hand, BLA GABAergic system did not interfere with the innate fear response because drug infusions had no effect in anxiety. Thus, retrieval alterations caused by the GABAergic drugs were probably related specifically to memory processes

Job satisfaction and discrepancies between social and biological timing

The discrepancies between social and biological timing are reflected in shift workers' well-being. The aim of this study was to verify the association between job satisfaction and chronotype among day and night nursing personnel. Several variables, including seniority at the hospital and, in the same shift, sleep duration, quality of sleep, sleepiness and willingness to change sleep timing were also analyzed. Chronotype was calculated by using the morningness-eveningness questionnaire. We studied 514 nursing professionals from a public university hospital. Among the day workers, the higher the morningness, the more the workers were satisfied with their job. In contrast, among night workers, job satisfaction was associated with sleep quality and seniority at the hospital but not with chronotype. Our results suggest that an agreement between work schedule and chronotype may help to increase job satisfaction among diurnal workers.

Investigations on the G-protein involved in Cnidarian phototransduction

This study aimed to investigate which genes Cnidaria use for photoreception and test whether Gi alpha subunit protein is involved in the phototransduction cascade, giving additional tools to investigate light-mediated behaviors, as nematocyte firing. Here, I engineered an opsin gene promoter construct useful to test whether nematocyte sensory cells express opsin gene. By determining the expression of one of the unique EST opsin genes of the eyeless hydrozoan Hydra magnipapillata genome in nematocyte sensory cells, we will be able to investigate whether light modulation is an ancestral feature in Cnidaria, and whether regulation of nematocyte discharge by opsin-mediated phototransduction predated this pathway’s function in cnidarian eyes. Nematocytes, the cnidarians stinging cells, discharge nematocysts to capture prey. As nematocysts are energetically expensive, the discharge is tightly regulated and occurs after proper chemical and mechanical stimulation. Cnidarians are also known to display a rich corpus of photobehaviors, which are often associated with activities that involve nematocytes. Previous experiments on nematocyst firing modulation show that light decreases nematocyte firing. This study contributed to confirm that bright light decreases the tendency for nematocytes to discharge in Haliplanella luciae. Similar findings in cubozoan and hydrozoan lead us to believe that light modulation of cnidocytes may be an ancestral feature of Cnidaria. Experimentally, I found no evidence that pertussis toxin, a Gi alpha subunit protein inhibitor, ablates Hydra magnipapillata photobehaviour, preliminary suggesting that Gi alpha subunit protein is not involved in photoresponse. I found no significant association between pertussis toxin and nematocyte firing in Haliplanella luciae both in conditions of dim and bright light, suggesting that Gi alpha subunit protein is not involved in photoresponse. We have preliminary evidence for a prevalence of photoreception over chemoreception, tending toward conditions of bright light. This finding may suggest the involvement of a Gs alpha subunit protein in Haliplanella luciae phototransduction pathway. While nematocyte chemo- and mechano-sensitivity have been extensively studied, further research is necessary to better understand what an ancestral phototransduction cascade looked like, and how opsin-based phototransduction acts to regulate nematocyte discharge.

A circadian clock regulates rod and cone input to fish retinal cone horizontal cells.

In the vertebrate retina, the light responses of post-receptor neurons depend on the ambient or background illumination. Using intracellular recording, we have found that a circadian clock regulates the light responses of dark-adapted fish cone horizontal cells. Goldfish were maintained on a 12-hr light/12-hr dark cycle. At different times of the day or night, retinas were superfused in darkness for 90 min ("prolonged darkness"), following which horizontal cells were impaled without the aid of any light flashes. In some of the experiments, fish were kept in constant darkness for 3-48 hr prior to surgery. After prolonged darkness during the night, but not during the day, the light responses of L-type cone horizontal cells resembled those of rod horizontal cells with respect to threshold, waveform, intensity-response functions, and spectral sensitivity. Following light sensitization during the night and day, the light responses of rod and cone horizontal cells were clearly different with respect to threshold, waveform, intensity-response functions, and spectral sensitivity. Under conditions of constant darkness for two full light/dark cycles, average responses of cone horizontal cells to a bright light stimulus during the subjective day were greater than during the subjective night. Prior reversal of the light/dark cycle reversed the 24-hr rhythm of cone horizontal cell responses to bright lights. In addition, following one full cycle of constant darkness, average cone horizontal cell spectral sensitivity during the subjective night closely matched that of rod horizontal cells, whereas average cone horizontal cell spectral sensitivity during the subjective day was similar to that of red (625 nm) cones. These results indicate that the effects of dark adaptation depend on the time of day and are regulated by a circadian clock so that cone input to cone horizontal cells predominates in the day and rod input predominates in the night.

A behavioral screen for isolating zebrafish mutants with visual system defects.

Optokinetic and phototactic behaviors of zebrafish larvae were examined for their usefulness in screening for recessive defects in the visual system. The optokinetic response can be reliably and rapidly detected in 5-day larvae, whereas the phototactic response of larvae is variable and not robust enough to be useful for screening. We therefore measured optokinetic responses of mutagenized larvae as a genetic screen for visual system defects. Third-generation larvae, representing 266 mutagenized genomes, were examined for abnormal optokinetic responses. Eighteen optokinetic-defective mutants were identified and two mutants that did not show obvious morphological defects, no optokinetic response a (noa) and partial optokinetic response a (poa), were studied further. We recorded the electroretinogram (ERG) to determine whether these two mutations affect the retina. The b-wave of noa larvae was grossly abnormal, being delayed in onset and significantly reduced in amplitude. In contrast, the ERG waveform of poa larvae was normal, although the b-wave was reduced in amplitude in bright light. Histologically, the retinas of noa and poa larvae appeared normal. We conclude that noa larvae have a functional defect in the outer retina, whereas the outer retina of poa larvae is likely to be normal.

Les effets de l’éclairage cyclique versus l’éclairage tamisé constant sur la stabilité physiologique et le niveau d’activité motrice de prématurés

Problématique : Les prématurés évoluent dans l’unité néonatale qui présente une intensité lumineuse parfois forte et variable, ce qui a pour effet de provoquer une instabilité physiologique, ainsi qu’une augmentation du niveau d’activité motrice chez ces derniers. Par ailleurs, le contrôle de l’éclairage à l’unité néonatale favorise la stabilité physiologique et réduit le niveau d’activité motrice des prématurés. Deux méthodes de contrôle de l’éclairage ont été étudiées, soit l’éclairage tamisé constant et l’éclairage cyclique. Or, la méthode de contrôle de l’éclairage la plus appropriée au système nerveux immature des prématurés est inconnue et il y a ambivalence en ce qui concerne les résultats des études ayant évalué ces deux modes de contrôle de l’éclairage. But : Le but de cette étude était de mesurer les effets de l’éclairage cyclique versus l’éclairage tamisé constant sur la stabilité physiologique et le niveau d’activité motrice de prématurés nés entre 28 et 32 semaines d’âge gestationnel. Méthode : Un essai clinique randomisé a été réalisé. Les 38 prématurés recrutés dans une unité néonatale de niveaux II et III d’un hôpital universitaire, ont été randomisés dans l’un des deux groupes d’intervention, soit le groupe exposé à l’éclairage tamisé constant ou celui exposé à l’éclairage cyclique. Ces deux types d’éclairage ont été appliqués pendant 24 heures. La stabilité physiologique a été mesurée par le score Stability of the Cardio Respiratory System in Premature Infants (SCRIP) et le niveau d’activité motrice a été mesuré avec un accéléromètre (Actiwatch®). L’intensité lumineuse à laquelle les prématurés ont été exposés a été mesurée de façon continue à l’intérieur de l’incubateur à l’aide d’un photomètre. Résultats : L’analyse des données révèle qu’il n’y aucune différence significative entre les deux groupes d’intervention en ce qui a trait à la stabilité physiologique (valeur-p du score SCRIP de 0,54 à 0,96) et au niveau d’activité motrice (valeur-p de 0,09 à 0,88). Les participants des deux groupes ont manifesté une stabilité physiologique et un niveau d’activité motrice comparables. Conclusion : Des interventions de contrôle de l’éclairage doivent être adoptées à l’unité néonatale, que ce soit des interventions qui permettent la mise en œuvre de l’éclairage cyclique ou de l’éclairage tamisé constant, dans le but de favoriser l’adaptation du prématuré à l’environnement de l’unité néonatale. Des recherches additionnelles sont requises afin d’identifier la méthode de contrôle de l’éclairage (éclairage cyclique ou éclairage tamisé constant) qui doit être implantée à l’unité néonatale.

Les effets de l’éclairage cyclique versus l’éclairage tamisé constant sur la stabilité physiologique et le niveau d’activité motrice de prématurés

Problématique : Les prématurés évoluent dans l’unité néonatale qui présente une intensité lumineuse parfois forte et variable, ce qui a pour effet de provoquer une instabilité physiologique, ainsi qu’une augmentation du niveau d’activité motrice chez ces derniers. Par ailleurs, le contrôle de l’éclairage à l’unité néonatale favorise la stabilité physiologique et réduit le niveau d’activité motrice des prématurés. Deux méthodes de contrôle de l’éclairage ont été étudiées, soit l’éclairage tamisé constant et l’éclairage cyclique. Or, la méthode de contrôle de l’éclairage la plus appropriée au système nerveux immature des prématurés est inconnue et il y a ambivalence en ce qui concerne les résultats des études ayant évalué ces deux modes de contrôle de l’éclairage. But : Le but de cette étude était de mesurer les effets de l’éclairage cyclique versus l’éclairage tamisé constant sur la stabilité physiologique et le niveau d’activité motrice de prématurés nés entre 28 et 32 semaines d’âge gestationnel. Méthode : Un essai clinique randomisé a été réalisé. Les 38 prématurés recrutés dans une unité néonatale de niveaux II et III d’un hôpital universitaire, ont été randomisés dans l’un des deux groupes d’intervention, soit le groupe exposé à l’éclairage tamisé constant ou celui exposé à l’éclairage cyclique. Ces deux types d’éclairage ont été appliqués pendant 24 heures. La stabilité physiologique a été mesurée par le score Stability of the Cardio Respiratory System in Premature Infants (SCRIP) et le niveau d’activité motrice a été mesuré avec un accéléromètre (Actiwatch®). L’intensité lumineuse à laquelle les prématurés ont été exposés a été mesurée de façon continue à l’intérieur de l’incubateur à l’aide d’un photomètre. Résultats : L’analyse des données révèle qu’il n’y aucune différence significative entre les deux groupes d’intervention en ce qui a trait à la stabilité physiologique (valeur-p du score SCRIP de 0,54 à 0,96) et au niveau d’activité motrice (valeur-p de 0,09 à 0,88). Les participants des deux groupes ont manifesté une stabilité physiologique et un niveau d’activité motrice comparables. Conclusion : Des interventions de contrôle de l’éclairage doivent être adoptées à l’unité néonatale, que ce soit des interventions qui permettent la mise en œuvre de l’éclairage cyclique ou de l’éclairage tamisé constant, dans le but de favoriser l’adaptation du prématuré à l’environnement de l’unité néonatale. Des recherches additionnelles sont requises afin d’identifier la méthode de contrôle de l’éclairage (éclairage cyclique ou éclairage tamisé constant) qui doit être implantée à l’unité néonatale.

Ancient colour vision: Multiple opsin genes in the ancestral vertebrates

Molecular investigation of the origin of colour vision has discovered five visual pigment (opsin) genes, all of which are expressed in an agnathan (jawless) fish, the lamprey Geotria australis. Lampreys are extant representatives of an ancient group of vertebrates whose origins are thought to date back to at least the early Cambrian, approximately 540 million years ago [1.]. Phylogenetic analysis has identified the visual pigment opsin genes of G. australis as orthologues of the major classes of vertebrate opsin genes. Therefore, multiple opsin genes must have originated very early in vertebrate evolution, prior to the separation of the jawed and jawless vertebrate lineages, and thereby provided the genetic basis for colour vision in all vertebrate species. The southern hemisphere lamprey Geotria australis (Figure 1A,B) possesses a predominantly cone-based visual system designed for photopic (bright light) vision [2. S.P. Collin, I.C. Potter and C.R. Braekevelt, The ocular morphology of the southern hemisphere lamprey Geotria australis Gray, with special reference to optical specializations and the characterisation and phylogeny of photoreceptor types. Brain Behav. Evol. 54 (1999), pp. 96–111.2. and 3.]. Previous work identified multiple cone types suggesting that the potential for colour vision may have been present in the earliest members of this group. In order to trace the molecular evolution and origins of vertebrate colour vision, we have examined the genetic complement of visual pigment opsins in G. australis.

Tablet App halometer for the assessment of dysphotopsia

Purpose To assess the validity and repeatability of the Aston Halometer. Setting University clinic, United Kingdom. Design Prospective, repeated-measures experimental study. Methods The halometer comprises a bright light-emitting-diode (LED) glare source in the center of an iPad4. Letters subtending 0.21° (∼0.3 logMAR) were moved centrifugally from the LED in 0.05 degree steps in 8 orientations separated by 45 degrees for each of 4 contrast levels (1000, 500, 100, and 25 Weber contrast units [Cw]) in random order. Bangerter occlusion foils were inserted in front of the right eye to simulate monocular glare conditions in 20 subjects (mean age 27.7 ± 3.1 years). Subjects were positioned 2 meters from the screen in a dark room with the iPad controlled from an iPhone via Bluetooth operated by the researcher. The C-Quant straylight meter was also used with each of the foils to measure the level of straylight over the retina. Halometry and straylight repeatability was assessed at a second visit. Results Halo size increased with the different occlusion foils and target contrasts (F = 29.564, P <.001) as expected and in a pattern similar to straylight measures (F = 80.655, P <0.001). Lower contrast letters showed better sensitivity but larger glare-obscured areas, resulting in ceiling effects caused by the screen's field-of-view, with 500 Cw being the best compromise. Intraobserver and interobserver repeatability of the Aston Halometer was good (500Cw: 0.84 to 0.93 and 0.53 to 0.73) and similar to the straylight meter. Conclusion The halometer provides a sensitive, repeatable way of quantifying a patient-recognized form of disability glare in multiple orientations to add objectivity to subjectively reported discomfort glare.

Plasticity varies with boldness in a weakly-electric fish

The expression of animal personality is indicated by patterns of consistency in  individual behaviour. Often, the differences exhibited between individuals are consistent across situations. However, between some situations, this can be biased by variable levels of individual plasticity. The interaction between individual plasticity and animal personality can be illustrated by examining situation-sensitive personality traits such as boldness (i.e. risk-taking and exploration tendency). For the weakly electric fish Gnathonemus petersii, light condition is a major factor influencing behaviour. Adapted to navigate in low-light conditions, this species chooses to be more active in dark environments where risk from visual predators is lower. However, G. petersii also exhibit individual differences in their degree of behavioural change from light to dark. The present study, therefore, aims to  examine if an increase of motivation to explore in the safety of the dark, not only affects mean levels of boldness, but also the variation between individuals, as a result of differences  in individual plasticity.  Results: Boldness was consistent between a novel-object and a novel-environment situation in bright light. However, no consistency in boldness was noted between a bright (risky) and a  dark (safe) novel environment. Furthermore, there was a negative association between boldness and the degree of change across novel environments, with shier individuals  exhibiting greater behavioural plasticity.  Conclusions: This study highlights that individual plasticity can vary with personality. In  addition, the effect of light suggests that variation in boldness is situation specific. Finally,  there appears to be a trade-off between personality and individual plasticity with shy but  plastic individuals minimizing costs when perceiving risk and bold but stable individuals  consistently maximizing rewards, which can be maladaptive.

Efficient and bright polymer light emitting field effect transistors

Light emitting field effect transistors (LEFETs) are emerging as a multi-functional class of optoelectronic devices. LEFETs can simultaneously execute light emission and the standard logic functions of a transistor in a single architecture. However, current LEFET architectures deliver either high brightness or high efficiency but not both concurrently, thus limiting their use in technological applications. Here we show an LEFET device strategy that simultaneously improves brightness and efficiency. The key step change in LEFET performance arises from the bottom gate top-contact device architecture in which the source/drain electrodes are semitransparent and the active channel contains a bi-layer comprising of a high mobility charge-transporting polymer, and a yellow-green emissive polymer. A record external quantum efficiency (EQE) of 2.1% at 1000cd/m2 is demonstrated for polymer based bilayer LEFETs.

Contrast in luminescence characteristics (intense UV to bright visible light) of ZnO nanostructures with the variation in microstructure

We report the controlled variation of luminescence of ZnO nanostructures from intense ultraviolet to bright visible light. Deliberate addition of surfactants in the reaction medium not only leads to growth anisotropy of ZnO, but also alters the luminescence property. ZnO nanoclusters comprising of very fine particles with crystallite sizes approximate to 15-22nm were prepared in a non-aqueous medium, either from a single alcohol or from their mixtures. Introduction of the aqueous solution of the surfactant helps in altering the microstructure of ZnO nanostructure to nanorods, nanodumb-bells as well as the luminescence property. The as-prepared powder material is found to be well crystallized. Defects introduced by the surfactant in aqueous medium play an important role in substantial transition in the optical luminescence. Chromaticity coordinates were found to lie in the yellow region of color space. This gives an impression of white light emission from ZnO nanocrystals, when excited by a blue laser. Oxygen vacancy is described as the major defect responsible for visible light emission as quantified by X-ray photoelectron spectroscopy and Raman analysis.

Direct observation by time-resolved infrared spectroscopy of the bright and the dark excited states of the [Ru(phen)2(dppz)]2+ light-switch compound in solution and when bound to DNA

The [Ru(phen)2(dppz)]2+ complex (1) is non-emissive in water but is highly luminescent in organic solvents or when bound to DNA, making it a useful probe for DNA binding. To date, a complete mechanistic explanation for this “light-switch” effect is still lacking. With this in mind we have undertaken an ultrafast time resolved infrared (TRIR) study of 1 and directly observe marker bands between 1280–1450 cm-1, which characterise both the emissive “bright” and the non-emissive “dark” excited states of the complex, in CD3CN and D2O respectively. These characteristic spectral features are present in the [Ru(dppz)3]2+ solvent light-switch complex but absent in [Ru(phen)3]2+, which is luminescent in both solvents. DFT calculations show that the vibrational modes responsible for these characteristic bands are predominantly localised on the dppz ligand. Moreover, they reveal that certain vibrational modes of the “dark” excited state couple with vibrational modes of two coordinating water molecules, and through these to the bulk solvent, thus providing a new insight into the mechanism of the light-switch effect. We also demonstrate that the marker bands for the “bright” state are observed for both L- and D enantiomers of 1 when bound to DNA and that photo-excitation of the complex induces perturbation of the guanine and cytosine carbonyl bands. This perturbation is shown to be stronger for the L enantiomer, demonstrating the different binding site properties of the two enantiomers and the ability of this technique to determine the identity and nature of the binding site of such intercalators.