An experimental test of the contributions and condition dependence of microstructure and carotenoids in yellow plumage coloration.

PubMed

Shawkey, Matthew D; Hill, Geoffrey E; McGraw, Kevin J; Hood, Wendy R; Huggins, Kristal

2006-12-07

A combination of structural and pigmentary components is responsible for many of the colour displays of animals. Despite the ubiquity of this type of coloration, neither the relative contribution of structures and pigments to variation in such colour displays nor the relative effects of extrinsic factors on the structural and pigment-based components of such colour has been determined. Understanding the sources of colour variation is important because structures and pigments may convey different information to conspecifics. In an experiment on captive American goldfinches Carduelis tristis, we manipulated two parameters, carotenoid availability and food availability, known to affect the expression of carotenoid pigments in a full-factorial design. Yellow feathers from these birds were then analysed in two ways. First, we used full-spectrum spectrometry and high-performance liquid chromatography to examine the extent to which variation in white structural colour and total carotenoid content was associated with variation in colour properties of feathers. The carotenoid content of yellow feathers predicted two colour parameters (principal component 1--representing high values of ultraviolet and yellow chroma and low values of violet-blue chroma-and hue). Two different colour parameters (violet-blue and yellow chroma) from white de-pigmented feathers, as well as carotenoid content, predicted reflectance measurements from yellow feathers. Second, we determined the relative effects of our experimental manipulations on white structural colour and yellow colour. Carotenoid availability directly affected yellow colour, while food availability affected it only in combination with carotenoid availability. None of our manipulations had significant effects on the expression of white structural colour. Our results suggest that the contribution of microstructures to variation in the expression of yellow coloration is less than the contribution of carotenoid content, and that carotenoid deposition is more dependent on extrinsic variability than is the production of white structural colour.

Colour variations in the GRB 120327A afterglow

NASA Astrophysics Data System (ADS)

Melandri, A.; Covino, S.; Zaninoni, E.; Campana, S.; Bolmer, J.; Cobb, B. E.; Gorosabel, J.; Kim, J.-W.; Kuin, P.; Kuroda, D.; Malesani, D.; Mundell, C. G.; Nappo, F.; Sbarufatti, B.; Smith, R. J.; Steele, I. A.; Topinka, M.; Trotter, A. S.; Virgili, F. J.; Bernardini, M. G.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Ghirlanda, G.; Gomboc, A.; Greiner, J.; Guidorzi, C.; Haislip, J. B.; Hanayama, H.; Hanlon, L.; Im, M.; Ivarsen, K. M.; Japelj, J.; Jelínek, M.; Kawai, N.; Kobayashi, S.; Kopac, D.; LaCluyzé, A. P.; Martin-Carrillo, A.; Murphy, D.; Reichart, D. E.; Salvaterra, R.; Salafia, O. S.; Tagliaferri, G.; Vergani, S. D.

2017-10-01

Aims: We present a comprehensive temporal and spectral analysis of the long Swift GRB 120327A afterglow data to investigate possible causes of the observed early-time colour variations. Methods: We collected data from various instruments and telescopes in X-ray, ultraviolet, optical, and near-infrared bands, and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times. Results: The ultraviolet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2 × 104 s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour that is typical of long gamma-ray bursts. At early times a colour variation is observed in the ultraviolet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early-time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction. Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/607/A29

Temperature, but Not Available Energy, Affects the Expression of a Sexually Selected Ultraviolet (UV) Colour Trait in Male European Green Lizards

PubMed Central

Bajer, Katalin; Molnár, Orsolya; Török, János; Herczeg, Gábor

2012-01-01

Background Colour signals are widely used in intraspecific communication and often linked to individual fitness. The development of some pigment-based (e.g. carotenoids) colours is often environment-dependent and costly for the signaller, however, for structural colours (e.g. ultraviolet [UV]) this topic is poorly understood, especially in terrestrial ectothermic vertebrates. Methodology/Principal Findings In a factorial experiment, we studied how available energy and time at elevated body temperature affects the annual expression of the nuptial throat colour patch in male European green lizards (Lacerta viridis) after hibernation and before mating season. In this species, there is a female preference for males with high throat UV reflectance, and males with high UV reflectance are more likely to win fights. We found that (i) while food shortage decreased lizards' body condition, it did not affect colour development, and (ii) the available time for maintaining high body temperature affected the development of UV colour without affecting body condition or other colour traits. Conclusions/Significance Our results demonstrate that the expression of a sexually selected structural colour signal depends on the time at elevated body temperature affecting physiological performance but not on available energy gained from food per se in an ectothermic vertebrate. We suggest that the effect of high ambient temperature on UV colour in male L. viridis makes it an honest signal, because success in acquiring thermally favourable territories and/or effective behavioural thermoregulation can both be linked to individual quality. PMID:22479611

Geographic divergence and colour change in response to visual backgrounds and illumination intensity in bearded dragons.

PubMed

Cadena, Viviana; Smith, Kathleen R; Endler, John A; Stuart-Fox, Devi

2017-03-15

Animals may improve camouflage by both dynamic colour change and local evolutionary adaptation of colour but we have little understanding of their relative importance in colour-changing species. We tested for differences in colour change in response to background colour and light intensity in two populations of central bearded dragon lizards ( Pogona vitticeps ) representing the extremes in body coloration and geographical range. We found that bearded dragons change colour in response to various backgrounds and that colour change is affected by illumination intensity. Within-individual colour change was similar in magnitude in the two populations but varied between backgrounds. However, at the endpoints of colour change, each population showed greater similarity to backgrounds that were representative of the local habitat compared with the other population, indicating local adaptation to visual backgrounds. Our results suggest that even in species that change colour, both phenotypic plasticity and geographic divergence of coloration may contribute to improved camouflage. © 2017. Published by The Company of Biologists Ltd.

Period-Luminosity-Colour distribution and classification of Galactic oxygen-rich LPVs. I. Luminosity calibrations

NASA Astrophysics Data System (ADS)

Barthès, D.; Luri, X.; Alvarez, R.; Mennessier, M. O.

1999-11-01

The absolute K magnitudes and kinematic parameters of about 350 oxygen-rich Long-Period Variable stars are calibrated, by means of an up-to-date maximum-likelihood method, using Hipparcos parallaxes and proper motions together with radial velocities and, as additional data, periods and V-K colour indices. Four groups, differing by their kinematics and mean magnitudes, are found. For each of them, we also obtain the distributions of magnitude, period and de-reddened colour of the base population, as well as de-biased period-luminosity-colour relations and their two-dimensional projections. The SRa semiregulars do not seem to constitute a separate class of LPVs. The SRb appear to belong to two populations of different ages. In a PL diagram, they constitute two evolutionary sequences towards the Mira stage. The Miras of the disk appear to pulsate on a lower-order mode. The slopes of their de-biased PL and PC relations are found to be very different from the ones of the Oxygen Miras of the LMC. This suggests that a significant number of so-called Miras of the LMC are misclassified. This also suggests that the Miras of the LMC do not constitute a homogeneous group, but include a significant proportion of metal-deficient stars, suggesting a relatively smooth star formation history. As a consequence, one may not trivially transpose the LMC period-luminosity relation from one galaxy to the other Based on data from the Hipparcos astrometry satellite. Appendix B is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

Ultraviolet sensitivity and colour vision in raptor foraging.

PubMed

Lind, Olle; Mitkus, Mindaugas; Olsson, Peter; Kelber, Almut

2013-05-15

Raptors have excellent vision, yet it is unclear how they use colour information. It has been suggested that raptors use ultraviolet (UV) reflections from vole urine to find good hunting grounds. In contrast, UV plumage colours in songbirds such as blue tits are assumed to be 'hidden' communication signals, inconspicuous to raptors. This ambiguity results from a lack of knowledge about raptor ocular media transmittance, which sets the limit for UV sensitivity. We measured ocular media transmittance in common buzzards (Buteo buteo), sparrowhawks (Accipiter nisus), red kites (Milvus milvus) and kestrels (Falco tinnunculus) so that, for the first time, raptor UV sensitivity can be fully described. With this information, and new measurements of vole urine reflectance, we show that (i) vole urine is unlikely to provide a reliable visual signal to hunting raptors and (ii) blue tit plumage colours are more contrasting to blue tits than to sparrowhawks because of UV reflectance. However, as the difference between blue tit and sparrowhawk vision is subtle, we suggest that behavioural data are needed to fully resolve this issue. UV cues are of little or no importance to raptors in both vole and songbird interactions and the role of colour vision in raptor foraging remains unclear.

Two transitional type Ia supernovae located in the Fornax cluster member NGC 1404: SN 2007on and SN 2011iv

NASA Astrophysics Data System (ADS)

Gall, C.; Stritzinger, M. D.; Ashall, C.; Baron, E.; Burns, C. R.; Hoeflich, P.; Hsiao, E. Y.; Mazzali, P. A.; Phillips, M. M.; Filippenko, A. V.; Anderson, J. P.; Benetti, S.; Brown, P. J.; Campillay, A.; Challis, P.; Contreras, C.; Elias de la Rosa, N.; Folatelli, G.; Foley, R. J.; Fraser, M.; Holmbo, S.; Marion, G. H.; Morrell, N.; Pan, Y.-C.; Pignata, G.; Suntzeff, N. B.; Taddia, F.; Robledo, S. Torres; Valenti, S.

2018-03-01

We present an analysis of ultraviolet (UV) to near-infrared observations of the fast-declining Type Ia supernovae (SNe Ia) 2007on and 2011iv, hosted by the Fornax cluster member NGC 1404. The B-band light curves of SN 2007on and SN 2011iv are characterised by Δm15 (B) decline-rate values of 1.96 mag and 1.77 mag, respectively. Although they have similar decline rates, their peak B- and H-band magnitudes differ by 0.60 mag and 0.35 mag, respectively. After correcting for the luminosity vs. decline rate and the luminosity vs. colour relations, the peak B-band and H-band light curves provide distances that differ by 14% and 9%, respectively. These findings serve as a cautionary tale for the use of transitional SNe Ia located in early-type hosts in the quest to measure cosmological parameters. Interestingly, even though SN 2011iv is brighter and bluer at early times, by three weeks past maximum and extending over several months, its B - V colour is 0.12 mag redder than that of SN 2007on. To reconcile this unusual behaviour, we turn to guidance from a suite of spherical one-dimensional Chandrasekhar-mass delayed-detonation explosion models. In this context, 56Ni production depends on both the so-called transition density and the central density of the progenitor white dwarf. To first order, the transition density drives the luminosity-width relation, while the central density is an important second-order parameter. Within this context, the differences in the B - V colour evolution along the Lira regime suggest that the progenitor of SN 2011iv had a higher central density than SN 2007on. The photometry tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A58

Environmental effects on the shape variation of male ultraviolet patterns in the Brimstone butterfly ( Gonepteryx rhamni, Pieridae, Lepidoptera)

NASA Astrophysics Data System (ADS)

Pecháček, Pavel; Stella, David; Keil, Petr; Kleisner, Karel

2014-12-01

The males of the Brimstone butterfly ( Gonepteryx rhamni) have ultraviolet pattern on the dorsal surfaces of their wings. Using geometric morphometrics, we have analysed correlations between environmental variables (climate, productivity) and shape variability of the ultraviolet pattern and the forewing in 110 male specimens of G. rhamni collected in the Palaearctic zone. To start with, we subjected the environmental variables to principal component analysis (PCA). The first PCA axis (precipitation, temperature, latitude) significantly correlated with shape variation of the ultraviolet patterns across the Palaearctic. Additionally, we have performed two-block partial least squares (PLS) analysis to assess co-variation between intraspecific shape variation and the variation of 11 environmental variables. The first PLS axis explained 93 % of variability and represented the effect of precipitation, temperature and latitude. Along this axis, we observed a systematic increase in the relative area of ultraviolet colouration with increasing temperature and precipitation and decreasing latitude. We conclude that the shape variation of ultraviolet patterns on the forewings of male Brimstones is correlated with large-scale environmental factors.

Visual modelling suggests a weak relationship between the evolution of ultraviolet vision and plumage coloration in birds.

PubMed

Lind, O; Delhey, K

2015-03-01

Birds have sophisticated colour vision mediated by four cone types that cover a wide visual spectrum including ultraviolet (UV) wavelengths. Many birds have modest UV sensitivity provided by violet-sensitive (VS) cones with sensitivity maxima between 400 and 425 nm. However, some birds have evolved higher UV sensitivity and a larger visual spectrum given by UV-sensitive (UVS) cones maximally sensitive at 360-370 nm. The reasons for VS-UVS transitions and their relationship to visual ecology remain unclear. It has been hypothesized that the evolution of UVS-cone vision is linked to plumage colours so that visual sensitivity and feather coloration are 'matched'. This leads to the specific prediction that UVS-cone vision enhances the discrimination of plumage colours of UVS birds while such an advantage is absent or less pronounced for VS-bird coloration. We test this hypothesis using knowledge of the complex distribution of UVS cones among birds combined with mathematical modelling of colour discrimination during different viewing conditions. We find no support for the hypothesis, which, combined with previous studies, suggests only a weak relationship between UVS-cone vision and plumage colour evolution. Instead, we suggest that UVS-cone vision generally favours colour discrimination, which creates a nonspecific selection pressure for the evolution of UVS cones. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Ornamental comb colour predicts T-cell-mediated immunity in male red grouse Lagopus lagopus scoticus

NASA Astrophysics Data System (ADS)

Mougeot, Francois

2008-02-01

Sexual ornaments might reliably indicate the ability to cope with parasites and diseases, and a better ability to mount a primary inflammatory response to a novel challenge. Carotenoid-based ornaments are amongst the commonest sexual signals of birds and often influence mate choice. Because carotenoids are immuno-stimulants, signallers may trade-off allocating these to ornamental colouration or using them for immune responses, so carotenoid-based ornaments might be particularly useful as honest indicators of immuno-compentence. Tetraonid birds, such as the red grouse Lagopus lagopus scoticus, exhibit supra-orbital yellow red combs, a conspicuous ornament which functions in intra- and inter-sexual selection. The colour of combs is due to epidermal pigmentation by carotenoids, while their size is testosterone-dependent. In this study, I investigated whether comb characteristics, and in particular, comb colour, indicated immuno-competence in free-living male red grouse. I assessed T-cell-mediated immunity using a standardised challenge with phytohaemagglutinin. Red grouse combs reflect in the red and in the ultraviolet spectrum of light, which is not visible to humans but that grouse most likely see, so I measured comb colour across the whole bird visible spectrum (300 700 nm) using a reflectance spectrometer. I found that males with bigger and redder combs, but with less ultraviolet reflectance, had greater T-cell-mediated immune response. Comb colour predicted T-cell-mediated immune response better than comb size, indicating that the carotenoid-based colouration of this ornament might reliably signal this aspect of male quality.

The role of ultraviolet colour in the assessment of mimetic accuracy between Batesian mimics and their models: a case study using ant-mimicking spiders

NASA Astrophysics Data System (ADS)

Corcobado, Guadalupe; Herberstein, Marie E.; Pekár, Stano

2016-12-01

The use of ultraviolet (UV) cues for intra- and inter-specific communication is common in many animal species. Still, the role of UV signals under some predator-prey contexts, such as Batesian mimicry, is not clear. Batesian mimicry is a defensive strategy by which a palatable species (the mimic) resembles an unpalatable or noxious species (the model) to avoid predation. This strategy has evolved independently in many different taxa that are predated by species capable of UV perception. Moreover, there is considerable variation in how accurately Batesian mimics resemble their models across species. Our aim was to investigate how UV colour contributed to mimetic accuracy using several ant-mimicking spider species as a case study. We measured the reflectance spectrum (300-700 nm) for several species of mimics and models, and we tested whether they differ in visible and UV colour. We modelled whether two different predators could discriminate between mimics and models using colour information. We found that generally, ant-mimicking spiders differed significantly from their ant models in UV colour and that information from the visible range of light cannot be extrapolated into the UV. Our modelling suggested that wasps should be able to discriminate between mimics and models combining information from visible and the UV light, whereas birds may not discriminate between them. Thus, we show that UV colour can influence mimic accuracy and we discuss its potential role in Batesian mimicry. We conclude that colour, especially in the UV range, should be taken into account when measuring mimetic accuracy.

The physiological and phenotypic determinants of human tanning measured as change in skin colour following a single dose of ultraviolet B radiation.

PubMed

Wong, Terence H; Jackson, Ian J; Rees, Jonathan L

2010-07-01

Experimental study of the in vivo kinetics of tanning in human skin has been limited by the difficulties in measuring changes in melanin pigmentation independent of the ultravioletinduced changes in erythema. The present study attempted to experimentally circumvent this issue. We have studied erythemal and tanning responses following a single exposure to a range of doses of ultraviolet B irradiation on the buttock and the lower back in 98 subjects. Erythema was assessed using reflectance techniques at 24 h and tanning measured as the L* spectrophotometric score at 7 days following noradrenaline iontophoresis. We show that dose (P < 0.0001), body site (P < 0.0001), skin colour (P < 0.0001), ancestry (P = 0.0074), phototype (P = 0.0019) and sex (P = 0.04) are all independent predictors of erythema. Quantitative estimates of the effects of these variables are reported, but the effects of ancestry and phototype do not appear solely explainable in terms of L* score. Dose (P < 0.0001), body site (P < 0.0001) and skin colour (P = 0.0365) or, as an alternative to skin colour, skin type (P = 0.0193) predict tanning, with those with lighter skin tanning slightly more to a defined UVB dose. If erythema is factored into the regression, then only dose and body site remain significant predictors of tanning: therefore neither phototype nor pigmentary factors, such as baseline skin colour, or eye or hair colour, predict change in skin colour to a unit erythemal response.

Galaxy And Mass Assembly (GAMA): colour- and luminosity-dependent clustering from calibrated photometric redshifts

NASA Astrophysics Data System (ADS)

Christodoulou, L.; Eminian, C.; Loveday, J.; Norberg, P.; Baldry, I. K.; Hurley, P. D.; Driver, S. P.; Bamford, S. P.; Hopkins, A. M.; Liske, J.; Peacock, J. A.; Bland-Hawthorn, J.; Brough, S.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

2012-09-01

We measure the two-point angular correlation function of a sample of 4289 223 galaxies with r < 19.4 mag from the Sloan Digital Sky Survey (SDSS) as a function of photometric redshift, absolute magnitude and colour down to Mr - 5 log h = -14 mag. Photometric redshifts are estimated from ugriz model magnitudes and two Petrosian radii using the artificial neural network package ANNz, taking advantage of the Galaxy And Mass Assembly (GAMA) spectroscopic sample as our training set. These photometric redshifts are then used to determine absolute magnitudes and colours. For all our samples, we estimate the underlying redshift and absolute magnitude distributions using Monte Carlo resampling. These redshift distributions are used in Limber's equation to obtain spatial correlation function parameters from power-law fits to the angular correlation function. We confirm an increase in clustering strength for sub-L* red galaxies compared with ˜L* red galaxies at small scales in all redshift bins, whereas for the blue population the correlation length is almost independent of luminosity for ˜L* galaxies and fainter. A linear relation between relative bias and log luminosity is found to hold down to luminosities L ˜ 0.03L*. We find that the redshift dependence of the bias of the L* population can be described by the passive evolution model of Tegmark & Peebles. A visual inspection of a random sample from our r < 19.4 sample of SDSS galaxies reveals that about 10 per cent are spurious, with a higher contamination rate towards very faint absolute magnitudes due to over-deblended nearby galaxies. We correct for this contamination in our clustering analysis.

Pterin pigments amplify iridescent ultraviolet signal in males of the orange sulphur butterfly, Colias eurytheme

PubMed Central

Rutowski, R.L; Macedonia, J.M; Morehouse, N; Taylor-Taft, L

2005-01-01

Animal colouration is typically the product of nanostructures that reflect or scatter light and pigments that absorb it. The interplay between these colour-producing mechanisms may influence the efficacy and potential information content of colour signals, but this notion has received little empirical attention. Wing scales in the male orange sulphur butterfly (Colias eurytheme) possess ridges with lamellae that produce a brilliant iridescent ultraviolet (UV) reflectance via thin-film interference. Curiously, these same scales contain pterin pigments that strongly absorb wavelengths below 550 nm. Given that male UV reflectance functions as a sexual signal in C. eurytheme, it is paradoxical that pigments in the wing scales are highly UV absorbing. We present spectrophotometric analyses of the wings before and after pterin removal that show that pterins both depress the amplitude of UV iridescence and suppress a diffuse UV reflectance that emanates from the scales. This latter effect enhances the directionality and spectral purity of the iridescence, and increases the signal's chromaticity and potential signal content. Our findings also suggest that pterins amplify the contrast between iridescent UV reflectance and scale background colour as a male's wings move during flight. PMID:16191648

Pterin pigments amplify iridescent ultraviolet signal in males of the orange sulphur butterfly, Colias eurytheme.

PubMed

Rutowski, R L; Macedonia, J M; Morehouse, N; Taylor-Taft, L

2005-11-07

Animal colouration is typically the product of nanostructures that reflect or scatter light and pigments that absorb it. The interplay between these colour-producing mechanisms may influence the efficacy and potential information content of colour signals, but this notion has received little empirical attention. Wing scales in the male orange sulphur butterfly (Colias eurytheme) possess ridges with lamellae that produce a brilliant iridescent ultraviolet (UV) reflectance via thin-film interference. Curiously, these same scales contain pterin pigments that strongly absorb wavelengths below 550 nm. Given that male UV reflectance functions as a sexual signal in C. eurytheme, it is paradoxical that pigments in the wing scales are highly UV absorbing. We present spectrophotometric analyses of the wings before and after pterin removal that show that pterins both depress the amplitude of UV iridescence and suppress a diffuse UV reflectance that emanates from the scales. This latter effect enhances the directionality and spectral purity of the iridescence, and increases the signal's chromaticity and potential signal content. Our findings also suggest that pterins amplify the contrast between iridescent UV reflectance and scale background colour as a male's wings move during flight.

In vitro assessment of ultraviolet protection of coloured cotton knitted fabrics with different structures under stretched and wet conditions.

PubMed

Wong, W Y; Lam, J K C; Kan, C W; Postle, R

2015-04-01

Clothing provides intrinsic ultraviolet (UV) protection that can be improved by colouration. However, the daily wearing condition can undermine the UV protection of coloured clothing wherein garments are stretched by body movement and/or wetted by perspiration of wearers. Knitwear is an indispensable clothing in summer, but its UV protection against wearing conditions lacks extensive study especially in a fabric structural approach. This article aimed at narrowing the research gap by focusing on the UV protection against stretch and wetness provided by various knitted fabric constructions incorporating the knit, tuck and miss stitches. The results show that the black knitted fabrics exhibit a significant reduction in the UV protection factor by 53% on average at a 10% stretch level. Knitted fabrics with miss stitches retained good UV protection even when the fabrics were stretched by 20% of its original dimensions. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Search for Type Ia supernova NUV-optical subclasses

NASA Astrophysics Data System (ADS)

Cinabro, David; Scolnic, Daniel; Kessler, Richard; Li, Ashley; Miller, Jake

2017-04-01

In response to a recently reported observation of evidence for two classes of Type Ia supernovae (SNe Ia) distinguished by their brightness in the rest-frame near-ultraviolet (NUV), we search for the phenomenon in publicly available light-curve data. We use the SNANA supernova analysis package to simulate SN Ia light curves in the Sloan Digital Sky Survey (SDSS) Supernova Search and the Supernova Legacy Survey (SNLS) with a model of two distinct ultraviolet classes of SNe Ia and a conventional model with a single broad distribution of SN-Ia ultraviolet brightnesses. We compare simulated distributions of rest-frame colours with these two models to those observed in 158 SNe Ia in the SDSS and SNLS data. The SNLS sample of 99 SNe Ia is in clearly better agreement with a model with one class of SN Ia light curves and shows no evidence for distinct NUV sub-classes. The SDSS sample of 59 SNe Ia with poorer colour resolution does not distinguish between the two models.

Colour preference and light sensitivity in trilobite larvae of mangrove horseshoe crab, Carcinoscopius rotundicauda (Latreille, 1802).

PubMed

Srijayat, T C; Pradeep, P J; Hassan, A; Chatterji, A; Shaharom, F; Jeffs, Andrew

2014-03-01

The trilobite larvae of C. rotundicauda were tested to determine their colour preference and light sensitivity until their first moulting (25 days post hatching) under laboratory conditions. Maximum congregation size of the trilobite larvae was found in the white zone respectively where (n = 12) followed by yellow (n = 8) and orange (n = 8), which showed the larval preference for lighter zones. Morisita's index calculation showed a clumped/aggregated distribution (yellow, blue, orange and white) and uniform/hyper dispersed distribution (green, red and black) for various colours tested. Trilobite larvae showed least preference for brighter regions while tested in the experiment [black; (n = 4) and red; (n = 5)]. Experiments done to determine the light sensitivity of trilobite larvae showed that the larvae had more preference towards ultraviolet lights. The maximum congregation size of 38.8 and 40.7% of the larvae was encountered under ultraviolet light, when the light sources were kept horizontal and vertical, respectively. Overall, results suggested that the trilobite larvae of C. rotundicauda, preferred light source of shorter wavelengths (UV light) and colours of lighter zone (white, yellow, orange), which might be due to their adaptation to their natural habitat for predator avoidance, prey selection and water quality.

Structure of the Large Magellanic Cloud from near infrared magnitudes of red clump stars

NASA Astrophysics Data System (ADS)

Subramanian, S.; Subramaniam, A.

2013-04-01

Context. The structural parameters of the disk of the Large Magellanic Cloud (LMC) are estimated. Aims: We used the JH photometric data of red clump (RC) stars from the Magellanic Cloud Point Source Catalog (MCPSC) obtained from the InfraRed Survey Facility (IRSF) to estimate the structural parameters of the LMC disk, such as the inclination, i, and the position angle of the line of nodes (PAlon), φ. Methods: The observed LMC region is divided into several sub-regions, and stars in each region are cross-identified with the optically identified RC stars to obtain the near infrared magnitudes. The peak values of H magnitude and (J - H) colour of the observed RC distribution are obtained by fitting a profile to the distributions and by taking the average value of magnitude and colour of the RC stars in the bin with largest number. Then the dereddened peak H0 magnitude of the RC stars in each sub-region is obtained from the peak values of H magnitude and (J - H) colour of the observed RC distribution. The right ascension (RA), declination (Dec), and relative distance from the centre of each sub-region are converted into x,y, and z Cartesian coordinates. A weighted least square plane fitting method is applied to this x,y,z data to estimate the structural parameters of the LMC disk. Results: An intrinsic (J - H)0 colour of 0.40 ± 0.03 mag in the Simultaneous three-colour InfraRed Imager for Unbiased Survey (SIRIUS) IRSF filter system is estimated for the RC stars in the LMC and a reddening map based on (J - H) colour of the RC stars is presented. When the peaks of the RC distribution were identified by averaging, an inclination of 25°.7 ± 1°.6 and a PAlon = 141°.5 ± 4°.5 were obtained. We estimate a distance modulus, μ = 18.47 ± 0.1 mag to the LMC. Extra-planar features which are both in front and behind the fitted plane are identified. They match with the optically identified extra-planar features. The bar of the LMC is found to be part of the disk within 500 pc. Conclusions: The estimates of the structural parameters are found to be independent of the photometric bands used for the analysis. The radial variation of the structural parameters are also studied. We find that the inner disk, within ~3°.0, is less inclined and has a larger value of PAlon when compared to the outer disk. Our estimates are compared with the literature values, and the possible reasons for the small discrepancies found are discussed.

First Results from the AKARI FU-HYU Mission Program

NASA Astrophysics Data System (ADS)

Pearson, C.; Serjeant, S.; Takagi, T.; Jeong, W.-S.; Negrello, M.; Matsuhara, H.; Wada, T.; Oyabu, S.; Lee, H. M.; Im, M.

2009-12-01

The AKARI FU-HYU mission program has carried out mid-infrared imaging of several well studied Spitzer fields. This imaging fills in the wavelength coverage lacking from the Spitzer surveys and gives an extremely high scientific return for minimal input for AKARI. We select fields already rich in multi-wavelength data from radio to X-ray wavelengths and present the results from our initial analysis in the GOODS-N field. We utilize the comprehansive multiwavelength coverage in the GOODS-N field to produce a multiwavelength catalogue from infrared to ultraviolet wavelengths including photometric redshifts. Using the FU-HYU catalogue we present colour-colour diagrams that map the passage of PAH features through our observation bands. These colour-colours diagrams are used as tools to extract anomalous colour populations, in particular a population of Silicate Break galaxies from the GOODS-N field.

The role of light, temperature and wine bottle colour on pigment enhancement in white wine.

PubMed

Dias, Daniel A; Smith, Trevor A; Ghiggino, Kenneth P; Scollary, Geoffrey R

2012-12-15

Pigmentation enhancement in a Chardonnay wine with high flavan-3-ol concentration was examined by irradiating the wine under controlled conditions. Heating the wine in darkness required temperatures in excess of 50°C before enhanced pigmentation became apparent. It was found that ultraviolet and, to a lesser extent, low wavelength visible light contributed to pigment production. The development of pigmentation depended on wine bottle glass colour: Flint>Arctic Blue>French Green>Antique Green. This is in agreement with the transmission characteristics of the bottles with even the darkest (Antique Green) allowing the transmission of some ultraviolet light. Riboflavin, when added to the wine, degraded rapidly when exposed to radiation <400 nm. The degradation of riboflavin and the onset of colour development depended on the actual amounts as well as the ratio of riboflavin to flavan-3-ol, suggesting that a complex series of reactions are occurring. A degradation product of riboflavin may be contributing to the increase in absorbance in the visible region observed during light exposure. Copyright © 2012 Elsevier Ltd. All rights reserved.

The cuticle modulates ultraviolet reflectance of avian eggshells

PubMed Central

Fecheyr-Lippens, Daphne C.; Igic, Branislav; D'Alba, Liliana; Hanley, Daniel; Verdes, Aida; Holford, Mande; Waterhouse, Geoffrey I. N.; Grim, Tomas; Hauber, Mark E.; Shawkey, Matthew D.

2015-01-01

ABSTRACT Avian eggshells are variedly coloured, yet only two pigments, biliverdin and protoporphyrin IX, are known to contribute to the dramatic diversity of their colours. By contrast, the contributions of structural or other chemical components of the eggshell are poorly understood. For example, unpigmented eggshells, which appear white to the human eye, vary in their ultraviolet (UV) reflectance, which may be detectable by birds. We investigated the proximate mechanisms for the variation in UV-reflectance of unpigmented bird eggshells using spectrophotometry, electron microscopy, chemical analyses, and experimental manipulations. We specifically tested how UV-reflectance is affected by the eggshell cuticle, the outermost layer of most avian eggshells. The chemical dissolution of the outer eggshell layers, including the cuticle, increased UV-reflectance for only eggshells that contained a cuticle. Our findings demonstrate that the outer eggshell layers, including the cuticle, absorb UV-light, probably because they contain higher levels of organic components and other chemicals, such as calcium phosphates, compared to the predominantly calcite-based eggshell matrix. These data highlight the need to examine factors other than the known pigments in studies of avian eggshell colour. PMID:25964661

Prefrontal cortex contributions to episodic retrieval monitoring and evaluation.

PubMed

Cruse, Damian; Wilding, Edward L

2009-11-01

Although the prefrontal cortex (PFC) plays roles in episodic memory judgments, the specific processes it supports are not understood fully. Event-related potential (ERP) studies of episodic retrieval have revealed an electrophysiological modulation - the right-frontal ERP old/new effect - which is thought to reflect activity in PFC. The functional significance of this old/new effect remains a matter of debate, and this study was designed to test two accounts: (i) that the effect indexes processes linked to the monitoring or evaluation of the products of retrieval in service of task demands, or (ii) that it indexes the number of internal decisions required for a task judgment. Participants studied words in one of two colours. In a subsequent retrieval task, old (studied) and new words were presented in a neutral colour. Participants made initial old/new judgments, along with study colour judgments to words thought to be old. They also indicated their confidence (high/low) in the colour decision. Right-frontal ERP old/new effects were larger for high than for low confidence correct colour judgments, and the magnitude of the right-frontal effect was correlated with the proportions of low confidence judgments that were made. Because the numbers of decisions associated with these response categories are equivalent, these findings do not support a decision-based account of the right-frontal ERP old/new effect. Rather, the correlation between confidence and the magnitude of the effect links it with retrieval monitoring and evaluation processes.

Development of colour and firmness in strawberry crops is UV light sensitive, but colour is not a good predictor of several quality parameters.

PubMed

Ordidge, Matthew; García-Macías, Paulina; Battey, Nicholas H; Gordon, Michael H; John, Philip; Lovegrove, Julie A; Vysini, Eleni; Wagstaffe, Alexandra; Hadley, Paul

2012-06-01

Strawberry (Fragaria × ananassa Duchesne var. Elsanta) plants were grown in polytunnels covered with three polythene films that transmitted varying levels of ultraviolet (UV) light. Fruit were harvested under near-commercial conditions and quality and yield were measured. During ripening, changes in the colour parameters of individual fruit were monitored, and the accuracy of using surface colour to predict other quality parameters was determined by analysing the correlation between colour and quality parameters within UV treatments. Higher exposure to UV during growth resulted in the fruit becoming darker at harvest and developing surface colour more quickly; fruit were also firmer at harvest, but shelf life was not consistently affected by the UV regime. Surface colour measurements were poorly correlated to firmness, shelf life or total phenolics, anthocyanins and ellagic acid contents. Although surface colour of strawberry fruits was affected by the UV regime during growth, and this parameter is an important factor in consumer perception, we concluded that the surface colour at the time of harvest was, contrary to consumer expectations, a poor indicator of firmness, potential shelf life or anthocyanin content. Copyright © 2011 Society of Chemical Industry.

Melanins in Fossil Animals: Is It Possible to Infer Life History Traits from the Coloration of Extinct Species?

PubMed Central

Negro, Juan J.; Finlayson, Clive; Galván, Ismael

2018-01-01

Paleo-colour scientists have recently made the transition from describing melanin-based colouration in fossil specimens to inferring life-history traits of the species involved. Two such cases correspond to counter-shaded dinosaurs: dark-coloured due to melanins dorsally, and light-coloured ventrally. We believe that colour reconstruction of fossils based on the shape of preserved microstructures—the majority of paleo-colour studies involve melanin granules—is not without risks. In addition, animals with contrasting dorso-ventral colouration may be under different selection pressures beyond the need for camouflage, including, for instance, visual communication or ultraviolet (UV) protection. Melanin production is costly, and animals may invest less in areas of the integument where pigments are less needed. In addition, melanocytes exposed to UV radiation produce more melanin than unexposed melanocytes. Pigment economization may thus explain the colour pattern of some counter-shaded animals, including extinct species. Even in well-studied extant species, their diversity of hues and patterns is far from being understood; inferring colours and their functions in species only known from one or few specimens from the fossil record should be exerted with special prudence. PMID:29360744

Colour stability of maxillofacial silicone elastomers: a review of the literature.

PubMed

Kulkarni, R S; Nagda, S J

2014-09-01

Colour degradation is a serious limitation of maxillofacial silicone elastomers and most silicone facial prostheses have to be remade within 1 year due to colour deterioration. A comprehensive review of the literature was completed using MEDLINE and PubMed Library databases. This was supplemented with a manual search of selected journals and textbooks. English language articles published in peer-reviewed journals from 1966 to January 2012 in which colour stability of silicone elastomers was evaluated using standard research protocols were included. In all, 127 articles were identified and 23 met the inclusion criteria. Current literature reveals that average colour stability of maxillofacial silicone prostheses is 6-12 months, and inherent unstable nature of silicones is responsible for the color degradation. Opacifiers, oil pigments and inorganic colourants may have a protective effect on colour stability of prostheses. Organic colourants, ultraviolet (UV) light, cleansing solutions, dust and aging can adversely affect colour stability of silicone prostheses. A direct comparison between studies has not been possible, because of the differences in experimental set-up such as materials tested, colourants used, or method of aging. There appears to be a need for a standardised test protocol for colour stability of maxillofacial materials. Colour degradation limits the useful lifespan of maxillofacial silicones. Improvements in colour stability is possible with the use of certain nano opacifiers, UV absorbers, photoprotective agents, and use of inorganic pigments and metal oxides.

Seasonal Changes in Colour: A Comparison of Structural, Melanin- and Carotenoid-Based Plumage Colours

PubMed Central

Delhey, Kaspar; Burger, Claudia; Fiedler, Wolfgang; Peters, Anne

2010-01-01

Background Plumage coloration is important for bird communication, most notably in sexual signalling. Colour is often considered a good quality indicator, and the expression of exaggerated colours may depend on individual condition during moult. After moult, plumage coloration has been deemed fixed due to the fact that feathers are dead structures. Still, many plumage colours change after moult, although whether this affects signalling has not been sufficiently assessed. Methodology/Principal Findings We studied changes in coloration after moult in four passerine birds (robin, Erithacus rubecula; blackbird, Turdus merula; blue tit, Cyanistes caeruleus; and great tit, Parus major) displaying various coloration types (melanin-, carotenoid-based and structural). Birds were caught regularly during three years to measure plumage reflectance. We used models of avian colour vision to derive two variables, one describing chromatic and the other achromatic variation over the year that can be compared in magnitude among different colour types. All studied plumage patches but one (yellow breast of the blue tit) showed significant chromatic changes over the year, although these were smaller than for a typical dynamic trait (bill colour). Overall, structural colours showed a reduction in relative reflectance at shorter wavelengths, carotenoid-based colours the opposite pattern, while no general pattern was found for melanin-based colours. Achromatic changes were also common, but there were no consistent patterns of change for the different types of colours. Conclusions/Significance Changes of plumage coloration independent of moult are probably widespread; they should be perceivable by birds and have the potential to affect colour signalling. PMID:20644723

Colour Changes on the Surface of the Rock Materials Due to UV-A and UV-B Rays

NASA Astrophysics Data System (ADS)

Binal, Adil; Ayderman, Aykut; Sel, Aylin

2015-04-01

The colour of the rocks used in the current buildings, and historical monuments is an important parameter in architecture and engineering. In addition, engineering geologists use the colour in order to identify the weathering class of rock material. The main colour of the stone, especially, are affected by the mineral size, the colour of the primary minerals and matrix material, as well as the colour of the accessory minerals. Due to atmospheric effects, changes in the outer surface colour of the rocks used as siding materials occur with over time. Factors causing the colour change are carbon dioxide (CO2), ozone (O3), sulphate (SO2, SO3) and nitrate (NOx) from the atmosphere with aerosols as well as UV rays from the sun. There is no more work in the literature on colour changes caused by UV-A and UV-B rays. In this study, the effects of ultraviolet in the colour of the surfaces of basalt, limestone, ignimbrite, travertine and sandstone have been simulated with a new experimental device in the laboratory medium. Lutron colour analyser (RGB-1002) was used for the measurements of RGB colours. Colour differences between the beginning and end of tests were determined with the standard practice for calculation of colour tolerances and colour differences from instrumentally measured colour coordinates (ASTM D2244). As a result of the experiments performed, lighten that seem on dark-grey micritic limestone (colour change ratio, CCR: 17.06) and basalt samples (CCR: 8.24) become even visually noticeable. Black and red ignimbrite samples having high porosity were presented the lower rate of colour changes. Finally, colour darkening has been observed in the light-coloured travertine (CCR: 13.8) and sandstone samples (CCR: 20.99).

The ATLAS3D project - XXVII. Cold gas and the colours and ages of early-type galaxies

NASA Astrophysics Data System (ADS)

Young, Lisa M.; Scott, Nicholas; Serra, Paolo; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Bureau, Martin; Crocker, Alison F.; Cappellari, Michele; Davies, Roger L.; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Weijmans, Anne-Marie

2014-11-01

We present a study of the cold gas contents of the ATLAS3D early-type galaxies, in the context of their optical colours, near-ultraviolet colours and Hβ absorption line strengths. Early-type (elliptical and lenticular) galaxies are not as gas poor as previously thought, and at least 40 per cent of local early-type galaxies are now known to contain molecular and/or atomic gas. This cold gas offers the opportunity to study recent galaxy evolution through the processes of cold gas acquisition, consumption (star formation) and removal. Molecular and atomic gas detection rates range from 10 to 34 per cent in red sequence early-type galaxies, depending on how the red sequence is defined, and from 50 to 70 per cent in blue early-type galaxies. Notably, massive red sequence early-type galaxies (stellar masses >5 × 1010 M⊙, derived from dynamical models) are found to have H I masses up to M(H I)/M* ˜ 0.06 and H2 masses up to M(H2)/M* ˜ 0.01. Some 20 per cent of all massive early-type galaxies may have retained atomic and/or molecular gas through their transition to the red sequence. However, kinematic and metallicity signatures of external gas accretion (either from satellite galaxies or the intergalactic medium) are also common, particularly at stellar masses ≤5 × 1010 M⊙, where such signatures are found in ˜50 per cent of H2-rich early-type galaxies. Our data are thus consistent with a scenario in which fast rotator early-type galaxies are quenched former spiral galaxies which have undergone some bulge growth processes, and in addition, some of them also experience cold gas accretion which can initiate a period of modest star formation activity. We discuss implications for the interpretation of colour-magnitude diagrams.

Photometric search for variable stars in the young open cluster Berkeley 59

NASA Astrophysics Data System (ADS)

Lata, Sneh; Pandey, A. K.; Maheswar, G.; Mondal, Soumen; Kumar, Brijesh

2011-12-01

We present the time series photometry of stars located in the extremely young open cluster Berkeley 59. Using the 1.04-m telescope at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, we have identified 42 variables in a field of ˜13 × 13 arcmin2 around the cluster. The probable members of the cluster have been identified using a (V, V-I) colour-magnitude diagram and a (J-H, H-K) colour-colour diagram. 31 variables have been found to be pre-main-sequence stars associated with the cluster. The ages and masses of the pre-main-sequence stars have been derived from the colour-magnitude diagram by fitting theoretical models to the observed data points. The ages of the majority of the probable pre-main-sequence variable candidates range from 1 to 5 Myr. The masses of these pre-main-sequence variable stars have been found to be in the range of ˜0.3 to ˜3.5 M⊙, and these could be T Tauri stars. The present statistics reveal that about 90 per cent T Tauri stars have period <15 d. The classical T Tauri stars are found to have a larger amplitude than the weak-line T Tauri stars. There is an indication that the amplitude decreases with an increase in mass, which could be due to the dispersal of the discs of relatively massive stars.

Ocular media transmission of coral reef fish--can coral reef fish see ultraviolet light?

PubMed

Siebeck, U E; Marshall, N J

2001-01-15

Many coral reef fish are beautifully coloured and the reflectance spectra of their colour patterns may include UVa wavelengths (315-400 nm) that are largely invisible to the human eye (Losey, G. S., Cronin, T. W., Goldsmith, T. H., David, H., Marshall, N. J., & McFarland, W.N. (1999). The uv visual world of fishes: a review. Journal of Fish Biology, 54, 921-943; Marshall, N. J. & Oberwinkler, J. (1999). The colourful world of the mantis shrimp. Nature, 401, 873-874). Before the possible functional significance of UV patterns can be investigated, it is of course essential to establish whether coral reef fishes can see ultraviolet light. As a means of tackling this question, in this study the transmittance of the ocular media of 211 coral reef fish species was measured. It was found that the ocular media of 50.2% of the examined species strongly absorb light of wavelengths below 400 nm, which makes the perception of UV in these fish very unlikely. The remaining 49.8% of the species studied possess ocular media that do transmit UV light, making the perception of UV possible.

Natural dyeing and UV protection of plasma treated cotton

NASA Astrophysics Data System (ADS)

Gorjanc, Marija; Mozetič, Miran; Vesel, Alenka; Zaplotnik, Rok

2018-03-01

Raw cotton fabrics have been exposed to low-pressure non-equilibrium gaseous plasma to improve the adsorption of natural dyes as well as ultraviolet (UV) protection factor. Plasma created in a glass tube by an electrodeless radiofrequency (RF) discharge was created either in oxygen or ammonia at the pressure of 50 Pa to stimulate formation of oxygen and nitrogen groups, respectively. The type and concentration of functional groups was determined by X-ray photoelectron spectroscopy (XPS) and morphological modifications by scanning electron microscopy (SEM). The colour yield for curcumin dye was improved significantly for samples treated with ammonia plasma what was explained by bonding of the dye to surface of amino groups. Contrary, the yield decreased when oxygen plasma treatment was applied due to the negatively charged surface that repels the negatively charged dye molecules. The effect was even more pronounced when using green tea extract as the colouring agent. The colour difference between the untreated and ammonia plasma treated sample increased linearly with plasma treatment time reaching the factor of 3.5 for treatment time of 300 s. The ultraviolet protection factor (UPF) was over 50 indicating excellent protection due to improved adsorption of the dye on the ammonia plasma treated samples.

Flower colours through the lens: quantitative measurement with visible and ultraviolet digital photography.

PubMed

Garcia, Jair E; Greentree, Andrew D; Shrestha, Mani; Dorin, Alan; Dyer, Adrian G

2014-01-01

The study of the signal-receiver relationship between flowering plants and pollinators requires a capacity to accurately map both the spectral and spatial components of a signal in relation to the perceptual abilities of potential pollinators. Spectrophotometers can typically recover high resolution spectral data, but the spatial component is difficult to record simultaneously. A technique allowing for an accurate measurement of the spatial component in addition to the spectral factor of the signal is highly desirable. Consumer-level digital cameras potentially provide access to both colour and spatial information, but they are constrained by their non-linear response. We present a robust methodology for recovering linear values from two different camera models: one sensitive to ultraviolet (UV) radiation and another to visible wavelengths. We test responses by imaging eight different plant species varying in shape, size and in the amount of energy reflected across the UV and visible regions of the spectrum, and compare the recovery of spectral data to spectrophotometer measurements. There is often a good agreement of spectral data, although when the pattern on a flower surface is complex a spectrophotometer may underestimate the variability of the signal as would be viewed by an animal visual system. Digital imaging presents a significant new opportunity to reliably map flower colours to understand the complexity of these signals as perceived by potential pollinators. Compared to spectrophotometer measurements, digital images can better represent the spatio-chromatic signal variability that would likely be perceived by the visual system of an animal, and should expand the possibilities for data collection in complex, natural conditions. However, and in spite of its advantages, the accuracy of the spectral information recovered from camera responses is subject to variations in the uncertainty levels, with larger uncertainties associated with low radiance levels.

The phylogenetic distribution of ultraviolet sensitivity in birds

PubMed Central

2013-01-01

Background Colour vision in birds can be categorized into two classes, the ultraviolet (UVS) and violet sensitive (VS). Their phylogenetic distributions have traditionally been regarded as highly conserved. However, the complicated nature of acquiring spectral sensitivities from cone photoreceptors meant that until recently, only a few species had actually been studied. Whether birds are UVS or VS can nowadays be inferred from a wide range of species via genomic sequencing of the UV/violet SWS1 cone opsin gene. Results We present genomic sequencing results of the SWS1 gene from 21 avian orders. Amino acid residues signifying UV sensitivity are found in the two most important spectral tuning sites 86 and 90 of Pteroclidiformes and Coraciiformes, in addition to the major clades, Palaeognathae, Charadriiformes, Trogoniformes, Psittaciformes and Passeriformes, where they where previously known to occur. We confirm that the presumed UVS-conferring amino acid combination F86, C90 and M93 is common to Palaeognathae and unique to this clade, despite available spectrometric evidence showing the ostrich retina to be VS. Conclusions By mapping our results together with data from previous studies on a molecular phylogeny we show that avian colour vision shifted between VS and UVS at least 14 times. Single nucleotide substitutions can explain all these shifts. The common ancestor of birds most likely had a VS phenotype. However, the ancestral state of the avian SWS1 opsin’s spectral tuning sites cannot be resolved, since the Palaeognathae are F86, C90 while the Neognathae are ancestrally S86, S90. The phylogenetic distribution of UVS and VS colour vision in birds is so complex that inferences of spectral sensitivities from closely related taxa should be used with caution. PMID:23394614

Light-induced pyroelectric effect as an effective approach for ultrafast ultraviolet nanosensing

NASA Astrophysics Data System (ADS)

Wang, Zhaona; Yu, Ruomeng; Pan, Caofeng; Li, Zhaoling; Yang, Jin; Yi, Fang; Wang, Zhong Lin

2015-09-01

Zinc oxide is potentially a useful material for ultraviolet detectors; however, a relatively long response time hinders practical implementation. Here by designing and fabricating a self-powered ZnO/perovskite-heterostructured ultraviolet photodetector, the pyroelectric effect, induced in wurtzite ZnO nanowires on ultraviolet illumination, has been utilized as an effective approach for high-performance photon sensing. The response time is improved from 5.4 s to 53 μs at the rising edge, and 8.9 s to 63 μs at the falling edge, with an enhancement of five orders in magnitudes. The specific detectivity and the responsivity are both enhanced by 322%. This work provides a novel design to achieve ultrafast ultraviolet sensing at room temperature via light-self-induced pyroelectric effect. The newly designed ultrafast self-powered ultraviolet nanosensors may find promising applications in ultrafast optics, nonlinear optics, optothermal detections, computational memories and biocompatible optoelectronic probes.

Observed Type II supernova colours from the Carnegie Supernova Project-I

NASA Astrophysics Data System (ADS)

de Jaeger, T.; Anderson, J. P.; Galbany, L.; González-Gaitán, S.; Hamuy, M.; Phillips, M. M.; Stritzinger, M. D.; Contreras, C.; Folatelli, G.; Gutiérrez, C. P.; Hsiao, E. Y.; Morrell, N.; Suntzeff, N. B.; Dessart, L.; Filippenko, A. V.

2018-06-01

We present a study of observed Type II supernova (SN II) colours using optical/near-infrared photometric data from the Carnegie Supernovae Project-I. We analyse four colours (B - V, u - g, g - r, and g - Y) and find that SN II colour curves can be described by two linear regimes during the photospheric phase. The first (s1, colour) is steeper and has a median duration of ˜40 d. The second, shallower slope (s2, colour) lasts until the end of the `plateau' (˜80 d). The two slopes correlate in the sense that steeper initial colour curves also imply steeper colour curves at later phases. As suggested by recent studies, SNe II form a continuous population of objects from the colour point of view as well. We investigate correlations between the observed colours and a range of photometric and spectroscopic parameters including the absolute magnitude, the V-band light-curve slopes, and metal-line strengths. We find that less luminous SNe II appear redder, a trend that we argue is not driven by uncorrected host-galaxy reddening. While there is significant dispersion, we find evidence that redder SNe II (mainly at early epochs) display stronger metal-line equivalent widths. Host-galaxy reddening does not appear to be a dominant parameter, neither driving observed trends nor dominating the dispersion in observed colours. Intrinsic SN II colours are most probably dominated by photospheric temperature differences, with progenitor metallicity possibly playing a minor role. Such temperature differences could be related to differences in progenitor radius, together with the presence or absence of circumstellar material close to the progenitor stars.

Nanostructural origin of blue fluorescence in the mineral karpatite.

PubMed

Potticary, Jason; Jensen, Torsten T; Hall, Simon R

2017-08-29

The colour of crystals is a function of their atomic structure. In the case of organic crystals, it is the spatial relationships between molecules that determine the colour, so the same molecules in the same arrangement should produce crystals of the same colour, regardless of whether they arise geologically or synthetically. There is a naturally-occurring organic crystal known as karpatite which is prized for its beautiful blue fluorescence under ultra-violet illumination. When grown under laboratory conditions however, the crystals fluoresce with an intense green colour. For 20 years, this difference has been thought to be due to chemical impurities in the laboratory-grown material. Using electron microscopy coupled with fluorescence spectroscopy and X-Ray diffraction, we report here that this disparity is instead due to differences in the structure of the crystals at the nanoscale. The results show that in nature, karpatite has a nanotexture that is not present in the synthetic crystals, which enables different photonic pathways and therefore a blue, rather than green colour whilst undergoing fluorescence.

Distinctive convergence in Australian floral colours seen through the eyes of Australian birds.

PubMed

Burd, Martin; Stayton, C Tristan; Shrestha, Mani; Dyer, Adrian G

2014-04-22

We used a colour-space model of avian vision to assess whether a distinctive bird pollination syndrome exists for floral colour among Australian angiosperms. We also used a novel phylogenetically based method to assess whether such a syndrome represents a significant degree of convergent evolution. About half of the 80 species in our sample that attract nectarivorous birds had floral colours in a small, isolated region of colour space characterized by an emphasis on long-wavelength reflection. The distinctiveness of this 'red arm' region was much greater when colours were modelled for violet-sensitive (VS) avian vision than for the ultraviolet-sensitive visual system. Honeyeaters (Meliphagidae) are the dominant avian nectarivores in Australia and have VS vision. Ancestral state reconstructions suggest that 31 lineages evolved into the red arm region, whereas simulations indicate that an average of five or six lineages and a maximum of 22 are likely to have entered in the absence of selection. Thus, significant evolutionary convergence on a distinctive floral colour syndrome for bird pollination has occurred in Australia, although only a subset of bird-pollinated taxa belongs to this syndrome. The visual system of honeyeaters has been the apparent driver of this convergence.

Ultraviolet reflectance by the cere of raptors

PubMed Central

Mougeot, François; Arroyo, Beatriz E

2006-01-01

Ultraviolet (UV) signals have been shown to play key roles in social and sexual signalling in birds. Using a spectrophotometer, we analysed the colour of the cere (skin above the beak) of a diurnal raptor, the Montagu's harrier (Circus pygargus), and show that it reflects in the UV part of the spectrum. The cere is a well-known sexual signal in raptors, with carotenoid based pigmentation being indicative of quality. We thus hypothesized that UV reflectance also signals quality. Accordingly, we found that in our sample of wild males, the location of the UV peak was related to the orangeness of cere and correlated with male body mass and condition (mass corrected for size). Also, males with brighter UV were mated to females that laid earlier, as expected if UV reflectance relates to a male's quality and attractiveness. Future studies should investigate the relationships between UV reflectance and carotenoid pigmentation of cere, and test how UV reflectance influences mate choice. PMID:17148356

Spectral reflectance properties of iridescent pierid butterfly wings.

PubMed

Wilts, Bodo D; Pirih, Primož; Stavenga, Doekele G

2011-06-01

The wings of most pierid butterflies exhibit a main, pigmentary colouration: white, yellow or orange. The males of many species have in restricted areas of the wing upper sides a distinct structural colouration, which is created by stacks of lamellae in the ridges of the wing scales, resulting in iridescence. The amplitude of the reflectance is proportional to the number of lamellae in the ridge stacks. The angle-dependent peak wavelength of the observed iridescence is in agreement with classical multilayer theory. The iridescence is virtually always in the ultraviolet wavelength range, but some species have a blue-peaking iridescence. The spectral properties of the pigmentary and structural colourations are presumably tuned to the spectral sensitivities of the butterflies' photoreceptors.

Energy transfer and colour tunability in UV light induced Tm3 +/Tb3 +/Eu3 +: ZnB glasses generating white light emission

NASA Astrophysics Data System (ADS)

Naresh, V.; Gupta, Kiran; Parthasaradhi Reddy, C.; Ham, Byoung S.

2017-03-01

A promising energy transfer (Tm3 + → Tb3 + → Eu3 +) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm3 +/Tb3 +/Eu3 + ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II)x-[O(- II)]y centres in the ZnB glass matrix. At 360 nm (UV) excitation, triply doped Tm3 +/Tb3 +/Eu3 +: ZnB glasses simultaneously shown their characteristic emission bands in blue (454 nm: 1D2 → 3F4), green (547 nm: 5D4 → 7F5) and red (616 nm: 5D0 → 7F2) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb3 + in ET from Tm3 + → Eu3 + was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb3 +, Eu3 +) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening.

Infrared observations of metal-deficient stars

NASA Astrophysics Data System (ADS)

Arribas, S.; Martinez Roger, C.

1987-09-01

Infrared magnitudes in the J, H, K and L bands for 64 metal-deficient stars spanning a wide range in effective temperature, luminosity and metal content are presented. An accuracy of 0.02 magnitude is obtained for the JHK bands and 0.03 for the L filter. Infrared-infrared and optical-infrared colour-colour diagrams are discussed and compared with the mean intrinsic tracks for Population I stars. It is concluded that infrared colours are not notably dependent on metallicity, with some exceptions for the reddest giants, which can be also interpreted by residual effects in the transformation equations between different systems. The authors also discuss briefly the near infrared photometric system of the Observatorio del Teide, from the Instituto de Astrofisica de Canarias.

Galaxy populations in the Antlia cluster - III. Properties of faint early-type galaxies

NASA Astrophysics Data System (ADS)

Smith Castelli, Analía. V.; Cellone, Sergio A.; Faifer, Favio R.; Bassino, Lilia P.; Richtler, Tom; Romero, Gisela A.; Calderón, Juan Pablo; Caso, Juan Pablo

2012-01-01

We present a new analysis of the early-type galaxy population in the central region of the Antlia cluster, focusing on the faint systems such as dwarf ellipticals (dEs) and dwarf spheroidals (dSphs). The colour-magnitude relation (CMR) and the relation between luminosity and mean effective surface brightness for galaxies in the central region of Antlia have been previously studied in Paper I of the present series. Now we confirm 22 early-type galaxies as Antlia members, using Gemini-GMOS and Magellan-MIKE spectra. Among them, 15 are dEs from the FS90 Antlia Group catalogue, two belong to the rare type of compact ellipticals (cEs) and five are new faint dwarfs that had never been catalogued before. In addition, we present 16 newly identified low-surface-brightness galaxy candidates, almost half of them displaying morphologies consistent with being Antlia's counterparts of Local Group dSphs, which extend the faint luminosity limit of our study down to MB=-10.1(BT= 22.6) mag. With these new data, we built an improved CMR in the Washington photometric system, i.e. integrated T1 magnitudes versus (C-T1) colours, which extends ˜4 mag faintwards the limit of spectroscopically confirmed Antlia members. When only confirmed early-type members are considered, this relation extends over 10 mag in luminosity with no apparent change in slope or increase in colour dispersion towards its faint end. The intrinsic colour scatter of the relation is compared with those reported for other clusters of galaxies; we argue that it is likely that the large scatter of the CMR, usually reported at faint magnitudes, is mostly due to photometric errors along with an improper membership/morphological classification. The distinct behaviour of the luminosity versus mean effective surface brightness relation at the bright and faint ends is analysed, while it is confirmed that dE galaxies on the same relation present a very similar effective radius, regardless of their colour. The projected spatial distribution of the member sample confirms the existence of two groups in Antlia, each one dominated by a giant elliptical galaxy and with one cE located close to each giant. Size and position, with respect to massive galaxies, of the dSph candidates are estimated and compared to Local Group counterparts. Based on observations carried out at the Cerro Tololo Inter-American Observatory (Chile), at Las Campanas Observatory (Chile) and at the European Southern Observatory, Paranal (Chile). Also based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministerio da Ciencia e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Attentional load attenuates synaesthetic priming effects in grapheme-colour synaesthesia.

PubMed

Mattingley, Jason B; Payne, Jonathan M; Rich, Anina N

2006-02-01

One of the hallmarks of grapheme-colour synaesthesia is that colours induced by letters, digits and words tend to interfere with the identification of coloured targets when the two colours are different, i.e., when they are incongruent. In a previous investigation (Mattingley et al., 2001) we found that this synaesthetic congruency effect occurs when an achromatic-letter prime precedes a coloured target, but that the effect disappears when the letter is pattern masked to prevent conscious recognition of its identity. Here we investigated whether selective attention modulates the synaesthetic congruency effect in a letter-priming task. Fourteen grapheme-colour synaesthetes and 14 matched, non-synaesthetic controls participated. The amount of selective attention available to process the letter-prime was limited by having participants perform a secondary visual task that involved discriminating pairs of gaps in adjacent limbs of a diamond surrounding the prime. In separate blocks of trials the attentional load of the secondary task was systematically varied to yield 'low load' and 'high load' conditions. We found a significant congruency effect for synaesthetes, but not for controls, when they performed a secondary attention-demanding task during presentation of the letter prime. Crucially, however, the magnitude of this priming was significantly reduced under conditions of high-load relative to low-load, indicating that attention plays an important role in modulating synaesthesia. Our findings help to explain the observation that synaesthetic colour experiences are often weak or absent during attention-demanding tasks.

A neuronal circuit for colour vision based on rod-cone opponency.

PubMed

Joesch, Maximilian; Meister, Markus

2016-04-14

In bright light, cone-photoreceptors are active and colour vision derives from a comparison of signals in cones with different visual pigments. This comparison begins in the retina, where certain retinal ganglion cells have 'colour-opponent' visual responses-excited by light of one colour and suppressed by another colour. In dim light, rod-photoreceptors are active, but colour vision is impossible because they all use the same visual pigment. Instead, the rod signals are thought to splice into retinal circuits at various points, in synergy with the cone signals. Here we report a new circuit for colour vision that challenges these expectations. A genetically identified type of mouse retinal ganglion cell called JAMB (J-RGC), was found to have colour-opponent responses, OFF to ultraviolet (UV) light and ON to green light. Although the mouse retina contains a green-sensitive cone, the ON response instead originates in rods. Rods and cones both contribute to the response over several decades of light intensity. Remarkably, the rod signal in this circuit is antagonistic to that from cones. For rodents, this UV-green channel may play a role in social communication, as suggested by spectral measurements from the environment. In the human retina, all of the components for this circuit exist as well, and its function can explain certain experiences of colour in dim lights, such as a 'blue shift' in twilight. The discovery of this genetically defined pathway will enable new targeted studies of colour processing in the brain.

A Bayesian Model of the Memory Colour Effect.

PubMed

Witzel, Christoph; Olkkonen, Maria; Gegenfurtner, Karl R

2018-01-01

According to the memory colour effect, the colour of a colour-diagnostic object is not perceived independently of the object itself. Instead, it has been shown through an achromatic adjustment method that colour-diagnostic objects still appear slightly in their typical colour, even when they are colourimetrically grey. Bayesian models provide a promising approach to capture the effect of prior knowledge on colour perception and to link these effects to more general effects of cue integration. Here, we model memory colour effects using prior knowledge about typical colours as priors for the grey adjustments in a Bayesian model. This simple model does not involve any fitting of free parameters. The Bayesian model roughly captured the magnitude of the measured memory colour effect for photographs of objects. To some extent, the model predicted observed differences in memory colour effects across objects. The model could not account for the differences in memory colour effects across different levels of realism in the object images. The Bayesian model provides a particularly simple account of memory colour effects, capturing some of the multiple sources of variation of these effects.

A Bayesian Model of the Memory Colour Effect

PubMed Central

Olkkonen, Maria; Gegenfurtner, Karl R.

2018-01-01

According to the memory colour effect, the colour of a colour-diagnostic object is not perceived independently of the object itself. Instead, it has been shown through an achromatic adjustment method that colour-diagnostic objects still appear slightly in their typical colour, even when they are colourimetrically grey. Bayesian models provide a promising approach to capture the effect of prior knowledge on colour perception and to link these effects to more general effects of cue integration. Here, we model memory colour effects using prior knowledge about typical colours as priors for the grey adjustments in a Bayesian model. This simple model does not involve any fitting of free parameters. The Bayesian model roughly captured the magnitude of the measured memory colour effect for photographs of objects. To some extent, the model predicted observed differences in memory colour effects across objects. The model could not account for the differences in memory colour effects across different levels of realism in the object images. The Bayesian model provides a particularly simple account of memory colour effects, capturing some of the multiple sources of variation of these effects. PMID:29760874

Ultraviolet reflecting photonic microstructures in the King Penguin beak.

PubMed

Dresp, Birgitta; Jouventin, Pierre; Langley, Keith

2005-09-22

King and emperor penguins (Aptenodytes patagonicus and Aptenodytes forsteri) are the only species of marine birds so far known to reflect ultraviolet (UV) light from their beaks. Unlike humans, most birds perceive UV light and several species communicate using the near UV spectrum. Indeed, UV reflectance in addition to the colour of songbird feathers has been recognized as an important signal when choosing a mate. The king penguin is endowed with several highly coloured ornaments, notably its beak horn and breast and auricular plumage, but only its beak reflects UV, a property considered to influence its sexual attraction. Because no avian UV-reflecting pigments have yet been identified, the origin of such reflections is probably structural. In an attempt to identify the structures that give rise to UV reflectance, we combined reflectance spectrophotometry and morphological analysis by both light and electron microscopy, after experimental removal of surface layers of the beak horn. Here, we characterize for the first time a multilayer reflector photonic microstructure that produces the UV reflections in the king penguin beak.

The case for cases B and C: intrinsic hydrogen line ratios of the broad-line region of active galactic nuclei, reddenings, and accretion disc sizes

NASA Astrophysics Data System (ADS)

Gaskell, C. Martin

2017-05-01

Low-redshift active galactic nuclei (AGNs) with extremely blue optical spectral indices are shown to have a mean, velocity-averaged, broad-line Hα/Hβ ratio of ≈2.72 ± 0.04, consistent with a Baker-Menzel Case B value. Comparison of a wide range of properties of the very bluest AGNs with those of a luminosity-matched subset of the Dong et al. blue AGN sample indicates that the only difference is the internal reddening. Ultraviolet fluxes are brighter for the bluest AGNs by an amount consistent with the flat AGN reddening curve of Gaskell et al. The lack of a significant difference in the GALEX (far-ultraviolet-near-ultraviolet) colour index strongly rules out a steep Small Magellanic Cloud-like reddening curve and also argues against an intrinsically harder spectrum for the bluest AGNs. For very blue AGNs, the Ly α/Hβ ratio is also consistent with being the Case B value. The Case B ratios provide strong support for the self-shielded broad-line model of Gaskell, Klimek & Nazarova. It is proposed that the greatly enhanced Ly α/Hβ ratio at very high velocities is a consequence of continuum fluorescence in the Lyman lines (Case C). Reddenings of AGNs mean that the far-UV luminosity is often underestimated by up to an order of magnitude. This is a major factor causing the discrepancies between measured accretion disc sizes and the predictions of simple accretion disc theory. Dust covering fractions for most AGNs are lower than has been estimated. The total mass in lower mass supermassive black holes must be greater than hitherto estimated.

Far-ultraviolet observation of the globular cluster NGC 6397

NASA Astrophysics Data System (ADS)

Dieball, A.; Rasekh, A.; Knigge, C.; Shara, M.; Zurek, D.

2017-07-01

We present an observational far-ultraviolet (FUV) and near-ultraviolet (NUV) study of the core region of the globular cluster (GC) NGC 6397. The observations were obtained with the Space Telescope Imaging Spectrograph (STIS, FUV) and the Wide Field Camera 3 (NUV) on board the Hubble Space Telescope. Here, we focus on the UV-bright stellar populations such as blue stragglers (BSs), white dwarfs (WDs) and cataclysmic variables (CVs). We present the first FUV - NUV colour-magnitude diagram (CMD) for this cluster. To support our classification of the stellar populations, we compare our FUV - NUV CMD with optical data from the ACS Survey of Galactic Globular Clusters. The FUV - NUV CMD indicates 16 sources located in the WD area, and 10 BSs within the 25 × 25 arcsec2 of the STIS FUV data. 18 Chandra X-ray sources are located within the FUV field of view. 13 of those have an NUV counterpart, of which 9 sources also have an FUV counterpart. Out of those, five sources are previously suggested CVs, and indeed, all five are located in the WD/CV region in our FUV - NUV CMD. Another CV has only an FUV but no NUV counterpart. We also detect an NUV (but no FUV) counterpart to the millisecond pulsar (MSP) located in the core of this cluster. The NUV light curves of the CVs and MSP show flickering behaviour typical of CVs. We found that the BSs and CVs are the most centrally concentrated populations. This might be an effect of mass segregation or it might indicate the preferred birth place of BSs and CVs via dynamical interactions in the dense core region of GCs. Horizontal branch stars are the least centrally concentrated population and absent in the innermost area of the core.

Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

NASA Astrophysics Data System (ADS)

Bero, M. A.; Abukassem, I.

2009-05-01

Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

Transformations between the 2MASS, SDSS, and BV I photometric systems for late-type giants

NASA Astrophysics Data System (ADS)

Yaz, E.; Bilir, S.; Karaali, S.; Ak, S.; Coşkunoğlu, B.; Cabrera-Lavers, A.

2010-08-01

We present colour transformations from Two Micron All Sky Survey (2MASS) photometric system to Johnson-Cousins system and to Sloan Digital Sky Survey (SDSS) system for late-type giants and vice versa. The giant star sample was formed using surface gravity constraints ({2 < log g ≤ 3}) to Cayrel de Strobel et al.' s (2001) spectroscopic catalogue. 2MASS, SDSS and Johnson-Cousins photometric data was taken from \\cite{Cu03}, \\cite{Ofek08}, and \\cite{vanLeeuwen2007}, respectively. The final sample was refined applying the following steps: (1) the data were dereddened, (2) the sample stars selected are of the highest photometric quality. We give two-colour dependent transformations as a function of metallicity as well as independent of metallicity. The transformations provide absolute magnitudes and distance determinations which can be used in space density evaluations at relatively short distances where some or all of the SDSS magnitudes of late-type giants are saturated.

Gaia Reveals Evidence for Merged White Dwarfs

NASA Astrophysics Data System (ADS)

Kilic, Mukremin; Hambly, N. C.; Bergeron, P.; Genest-Beaulieu, C.; Rowell, N.

2018-06-01

We use Gaia Data Release 2 to identify 13,928 white dwarfs within 100 pc of the Sun. The exquisite astrometry from Gaia reveals for the first time a bifurcation in the observed white dwarf sequence in both Gaia and the Sloan Digital Sky Survey (SDSS) passbands. The latter is easily explained by a helium atmosphere white dwarf fraction of 36%. However, the bifurcation in the Gaia colour-magnitude diagram depends on both the atmospheric composition and the mass distribution. We simulate theoretical colour-magnitude diagrams for single and binary white dwarfs using a population synthesis approach and demonstrate that there is a significant contribution from relatively massive white dwarfs that likely formed through mergers. These include white dwarf remnants of main-sequence (blue stragglers) and post-main sequence mergers. The mass distribution of the SDSS subsample, including the spectroscopically confirmed white dwarfs, also shows this massive bump. This is the first direct detection of such a population in a volume-limited sample.

Characterisation of interaction between food colourant allura red AC and human serum albumin: multispectroscopic analyses and docking simulations.

PubMed

Wu, Di; Yan, Jin; Wang, Jing; Wang, Qing; Li, Hui

2015-03-01

Binding interaction of human serum albumin (HSA) with allura red AC, a food colourant, was investigated at the molecular level through fluorescence, ultraviolet-visible, circular dichroism (CD) and Raman spectroscopies, as well as protein-ligand docking studies to better understand the chemical absorption, distribution and transportation of colourants. Results show that allura red AC has the ability to quench the intrinsic fluorescence of HSA through static quenching. The negative values of the thermodynamic parameters ΔG, ΔH, and ΔS indicated that hydrogen bond and van der Waals forces are dominant in the binding between the food colourant and HSA. The CD and Raman spectra showed that the binding of allura red AC to HSA induces the rearrangement of the carbonyl hydrogen-bonding network of polypeptides, which changes the HSA secondary structure. This colourant is bound to HSA in site I, and the binding mode was further analysed with the use of the CDOCKER algorithm in Discovery Studio. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Hubble Space Telescope UV Legacy Survey of Galactic globular clusters - XIV. Multiple stellar populations within M 15 and their radial distribution

NASA Astrophysics Data System (ADS)

Nardiello, D.; Milone, A. P.; Piotto, G.; Anderson, J.; Bedin, L. R.; Bellini, A.; Cassisi, S.; Libralato, M.; Marino, A. F.

2018-06-01

In the context of the Hubble Space Telescope UV Survey of Galactic globular clusters (GCs), we derived high-precision, multi-band photometry to investigate the multiple stellar populations in the massive and metal-poor GC M 15. By creating for red-giant branch (RGB) stars of the cluster a `chromosome map', which is a pseudo two-colour diagram made with appropriate combination of F275W, F336W, F438W, and F814W magnitudes, we revealed colour spreads around two of the three already known stellar populations. These spreads cannot be produced by photometric errors alone and could hide the existence of (two) additional populations. This discovery increases the complexity of the multiple-population phenomenon in M 15. Our analysis shows that M 15 exhibits a faint sub-giant branch (SGB), which is also detected in colour-magnitude diagrams (CMDs) made with optical magnitudes only. This poorly populated SGB includes about 5 per cent of the total number of SGB stars and evolves into a red RGB in the mF336W versus mF336W - mF814W CMD, suggesting that M 15 belongs to the class of Type II GCs. We measured the relative number of stars in each population at various radial distances from the cluster centre, showing that all of these populations share the same radial distribution within statistic uncertainties. These new findings are discussed in the context of the formation and evolution scenarios of the multiple populations.

Solvent-free optical recording of structural colours on pre-imprinted photocrosslinkable nanostructures

NASA Astrophysics Data System (ADS)

Jiang, Hao; Rezaei, Mohamad; Abdolahi, Mahssa; Kaminska, Bozena

2017-09-01

Optical digital information storage media, despite their ever-increasing storage capacity and data transfer rate, are vulnerable to the potential risk of turning inaccessible. For this reason, long-term eye-readable full-colour optical archival storage is in high demand for preserving valuable information from cultural, intellectual, and scholarly resources. However, the concurrent requirements in recording colours inexpensively and precisely, and preserving colours for the very long term (for at least 100 years), have not yet been met by existing storage techniques. Structural colours hold the promise to overcome such challenges. However, there is still the lack of an inexpensive, rapid, reliable, and solvent-free optical patterning technique for recording structural colours. In this paper, we introduce an enabling technique based on optical and thermal patterning of nanoimprinted SU-8 nanocone arrays. Using photocrosslinking and thermoplastic flow of SU-8, diffractive structural colours of nanocone arrays are recorded using ultra-violet (UV) exposure followed by the thermal development and reshaping of nanocones. Different thermal treatment procedures in reshaping nanocones are investigated and compared, and two-step progressive baking is found to allow the controllable reshaping of nanocones. The height of the nanocones and brightness of diffractive colours are modulated by varying the UV exposure dose to enable grey-scale patterning. An example of recorded full-colour image through half-tone patterning is also demonstrated. The presented technique requires only low-power continuous-wave UV light and is very promising to be adopted for professional and consumer archival storage applications.

Astrophysical parameters of open star clusters using 2MASS JHKs data

NASA Astrophysics Data System (ADS)

Durgapal, Alok; Bisht, Devendra; Yadav, Ramakant Singh

2018-04-01

In the present analysis we have estimated the fundamental parameters of two poorly studied open star clusters, namely Teutsch 61 and Czernik 3, using 2MASS JHKs data. We have used the color-magnitude and colour-colour diagrams to determine their fundamental parameters.

Luminosity function of faint galaxies with ultraviolet continuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stepanyan, D.A.

1985-05-01

The spatial density of faint galaxies with ultraviolet continuum in the Second Survey of the Byurakan Astrophysical Observatory is determined. The luminosity function of galaxies with ultraviolet continuum can be extended to objects fainter by 1-1.5 magnitudes. The spatial density of such galaxies in the interval of luminosities -16 /sup m/ .5 to -21 /sup m/ .5 is on the average 0.08 of the total density of field galaxies in the same interval of absolute magnitudes. The spatial density of low-luminosity galaxies with ultraviolet continuum is very high. In the interval from -12 /sup m/ .5 to -15 /sup m/more » .5 it is 0.23 Mpc/sup -3/.« less

Calibration and characterisation of the Gaia Red Clump

NASA Astrophysics Data System (ADS)

Ruiz-Dern, L.; Babusiaux, C.; Arenou, F.; Danielski, C.; Turon, C.; Sartoretti, P.

2018-04-01

We present new empirical Colour-Colour and Effective Temperature-Colour Gaia Red Clump calibrations. The selected sample takes into account high photometric quality, good spectrometric metallicity, homogeneous effective temperatures and low interstellar extinctions. From those calibrations we developed a method to derive the absolute magnitude, temperature and extinction of the Gaia RC. We tested our colour and extinction estimates on stars with measured spectroscopic effective temperatures and Diffuse Interstellar Band (DIB) constraints. Within the Gaia Validation team these calibrations are also being used, together with asteroseismic constraints, to check the parallax zero-point with Red Clump stars.

Colours of minor bodies in the outer solar system. II. A statistical analysis revisited

NASA Astrophysics Data System (ADS)

Hainaut, O. R.; Boehnhardt, H.; Protopapa, S.

2012-10-01

We present an update of the visible and near-infrared colour database of Minor Bodies in the Outer Solar System (MBOSSes), which now includes over 2000 measurement epochs of 555 objects, extracted from over 100 articles. The list is fairly complete as of December 2011. The database is now large enough to enable any dataset with a large dispersion to be safely identified and rejected from the analysis. The selection method used is quite insensitive to individual outliers. Most of the rejected datasets were observed during the early days of MBOSS photometry. The individual measurements are combined in a way that avoids possible rotational artifacts. The spectral gradient over the visible range is derived from the colours, as well as the R absolute magnitude M(1,1). The average colours, absolute magnitude, and spectral gradient are listed for each object, as well as the physico-dynamical classes using a classification adapted from Gladman and collaborators. Colour-colour diagrams, histograms, and various other plots are presented to illustrate and investigate class characteristics and trends with other parameters, whose significances are evaluated using standard statistical tests. Except for a small discrepancy for the J-H colour, the largest objects, with M(1,1) < 5, are indistinguishable from the smaller ones. The larger ones are slightly bluer than the smaller ones in J-H. Short-period comets, Plutinos and other resonant objects, hot classical disk objects, scattered disk objects and detached disk objects have similar properties in the visible, while the cold classical disk objects and the Jupiter Trojans form two separate groups of their spectral properties in the visible wavelength range. The well-known colour bimodality of Centaurs is confirmed. The hot classical disk objects with large inclinations, or large orbital excitations are found to be bluer than the others, confirming a previously known result. Additionally, the hot classical disk objects with a smaller perihelion distance are bluer than those that do not come as close to the Sun. The bluer hot classical disk objects and resonant objects have fainter absolute magnitudes than the redder ones of the same class. Finally, we discuss possible scenarios for the origin of the colour diversity observed in MBOSSes, i.e. colouration caused by evolutionary or formation processes. The colour tables and all plots are also available on the MBOSS colour web page, which will be updated when new measurements are published Full Tables 2 and 3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/546/A115

Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision.

PubMed

Cronin, Thomas W; Bok, Michael J; Marshall, N Justin; Caldwell, Roy L

2014-01-01

Stomatopod crustaceans have the most complex and diverse assortment of retinal photoreceptors of any animals, with 16 functional classes. The receptor classes are subdivided into sets responsible for ultraviolet vision, spatial vision, colour vision and polarization vision. Many of these receptor classes are spectrally tuned by filtering pigments located in photoreceptors or overlying optical elements. At visible wavelengths, carotenoproteins or similar substances are packed into vesicles used either as serial, intrarhabdomal filters or lateral filters. A single retina may contain a diversity of these filtering pigments paired with specific photoreceptors, and the pigments used vary between and within species both taxonomically and ecologically. Ultraviolet-filtering pigments in the crystalline cones serve to tune ultraviolet vision in these animals as well, and some ultraviolet receptors themselves act as birefringent filters to enable circular polarization vision. Stomatopods have reached an evolutionary extreme in their use of filter mechanisms to tune photoreception to habitat and behaviour, allowing them to extend the spectral range of their vision both deeper into the ultraviolet and further into the red.

Spectral energy distributions and colours of hot subluminous stars

NASA Astrophysics Data System (ADS)

Heber, Ulrich; Irrgang, Andreas; Schaffenroth, Johannes

2018-02-01

Photometric surveys at optical, ultraviolet, and infrared wavelengths provide ever-growing datasets as major surveys proceed. Colour-colour diagrams are useful tools to identify classes of star and provide large samples. However, combining all photometric measurements of a star into a spectral energy distribution will allow quantitative analyses to be carried out. We demonstrate how to construct and exploit spectral energy distributions and colours for sublumious B (sdB) stars. The aim is to identify cool companions to hot subdwarfs and to determine atmospheric parameters of apparently single sdB stars as well as composite spectrum sdB binaries.We analyse two sdB stars with high-quality photometric data which serve as our benchmarks, the apparently single sdB HD205805 and the sdB + K5 binary PG 0749+658, briefly present preliminary results for the sample of 142 sdB binaries with known orbits, and discuss future prospects from ongoing all-sky optical space- (Gaia) and ground-based (e.g. SkyMapper) as well as NIR surveys.

Disorder in convergent floral nanostructures enhances signalling to bees

NASA Astrophysics Data System (ADS)

Moyroud, Edwige; Wenzel, Tobias; Middleton, Rox; Rudall, Paula J.; Banks, Hannah; Reed, Alison; Mellers, Greg; Killoran, Patrick; Westwood, M. Murphy; Steiner, Ullrich; Vignolini, Silvia; Glover, Beverley J.

2017-10-01

Diverse forms of nanoscale architecture generate structural colour and perform signalling functions within and between species. Structural colour is the result of the interference of light from approximately regular periodic structures; some structural disorder is, however, inevitable in biological organisms. Is this disorder functional and subject to evolutionary selection, or is it simply an unavoidable outcome of biological developmental processes? Here we show that disordered nanostructures enable flowers to produce visual signals that are salient to bees. These disordered nanostructures (identified in most major lineages of angiosperms) have distinct anatomies but convergent optical properties; they all produce angle-dependent scattered light, predominantly at short wavelengths (ultraviolet and blue). We manufactured artificial flowers with nanoscale structures that possessed tailored levels of disorder in order to investigate how foraging bumblebees respond to this optical effect. We conclude that floral nanostructures have evolved, on multiple independent occasions, an effective degree of relative spatial disorder that generates a photonic signature that is highly salient to insect pollinators.

SPIDER - I. Sample and galaxy parameters in the grizYJHK wavebands

NASA Astrophysics Data System (ADS)

La Barbera, F.; de Carvalho, R. R.; de La Rosa, I. G.; Lopes, P. A. A.; Kohl-Moreira, J. L.; Capelato, H. V.

2010-11-01

This is the first paper of a series presenting the Spheroids Panchromatic Investigation in Different Environmental Regions (SPIDER). The sample of spheroids consists of 5080 bright (Mr < -20) early-type galaxies (ETGs), in the redshift range of 0.05 to 0.095, with optical (griz) photometry and spectroscopy from the Sloan Digital Sky Survey Data Release 6 (SDSS-DR6) and near-infrared (YJHK) photometry from the UKIRT Infrared Deep Sky Survey-Large Area Survey (UKIDSS-LAS) (DR4). We describe how homogeneous photometric parameters (galaxy colours and structural parameters) are derived using grizYJHK wavebands. We find no systematic steepening of the colour-magnitude relation when probing the baseline from g - r to g - K, implying that internal colour gradients drive most of the mass-metallicity relation in ETGs. As far as structural parameters are concerned we find that the mean effective radius of ETGs smoothly decreases, by 30 per cent, from g through K, while no significant dependence on waveband is detected for the axial ratio, Sersic index and a4 parameters. Furthermore, velocity dispersions are remeasured for all the ETGs using STARLIGHT and compared to those obtained by SDSS. The velocity dispersions are rederived using a combination of simple stellar population models as templates, hence accounting for the kinematics of different galaxy stellar components. We compare our (2DPHOT) measurements of total magnitude, effective radius and mean surface brightness with those obtained as part of the SDSS pipeline (PHOTO). Significant differences are found and reported, including comparisons with a third and independent part. A full characterization of the sample completeness in all wavebands is presented, establishing the limits of application of the characteristic parameters presented here for the analysis of the global scaling relations of ETGs.

Flower Colours through the Lens: Quantitative Measurement with Visible and Ultraviolet Digital Photography

PubMed Central

Garcia, Jair E.; Greentree, Andrew D.; Shrestha, Mani; Dorin, Alan; Dyer, Adrian G.

2014-01-01

Background The study of the signal-receiver relationship between flowering plants and pollinators requires a capacity to accurately map both the spectral and spatial components of a signal in relation to the perceptual abilities of potential pollinators. Spectrophotometers can typically recover high resolution spectral data, but the spatial component is difficult to record simultaneously. A technique allowing for an accurate measurement of the spatial component in addition to the spectral factor of the signal is highly desirable. Methodology/Principal findings Consumer-level digital cameras potentially provide access to both colour and spatial information, but they are constrained by their non-linear response. We present a robust methodology for recovering linear values from two different camera models: one sensitive to ultraviolet (UV) radiation and another to visible wavelengths. We test responses by imaging eight different plant species varying in shape, size and in the amount of energy reflected across the UV and visible regions of the spectrum, and compare the recovery of spectral data to spectrophotometer measurements. There is often a good agreement of spectral data, although when the pattern on a flower surface is complex a spectrophotometer may underestimate the variability of the signal as would be viewed by an animal visual system. Conclusion Digital imaging presents a significant new opportunity to reliably map flower colours to understand the complexity of these signals as perceived by potential pollinators. Compared to spectrophotometer measurements, digital images can better represent the spatio-chromatic signal variability that would likely be perceived by the visual system of an animal, and should expand the possibilities for data collection in complex, natural conditions. However, and in spite of its advantages, the accuracy of the spectral information recovered from camera responses is subject to variations in the uncertainty levels, with larger uncertainties associated with low radiance levels. PMID:24827828

Evolution of ultraviolet vision in the largest avian radiation - the passerines.

PubMed

Ödeen, Anders; Håstad, Olle; Alström, Per

2011-10-24

Interspecific variation in avian colour vision falls into two discrete classes: violet sensitive (VS) and ultraviolet sensitive (UVS). They are characterised by the spectral sensitivity of the most shortwave sensitive of the four single cones, the SWS1, which is seemingly under direct control of as little as one amino acid substitution in the cone opsin protein. Changes in spectral sensitivity of the SWS1 are ecologically important, as they affect the abilities of birds to accurately assess potential mates, find food and minimise visibility of social signals to predators. Still, available data have indicated that shifts between classes are rare, with only four to five independent acquisitions of UV sensitivity in avian evolution. We have classified a large sample of passeriform species as VS or UVS from genomic DNA and mapped the evolution of this character on a passerine phylogeny inferred from published molecular sequence data. Sequencing a small gene fragment has allowed us to trace the trait changing from one stable state to another through the radiation of the passeriform birds. Their ancestor is hypothesised to be UVS. In the subsequent radiation, colour vision changed between UVS and VS at least eight times. The phylogenetic distribution of SWS1 cone opsin types in Passeriformes reveals a much higher degree of complexity in avian colour vision evolution than what was previously indicated from the limited data available. Clades with variation in the colour vision system are nested among clades with a seemingly stable VS or UVS state, providing a rare opportunity to understand how an ecologically important trait under simple genetic control may co-evolve with, and be stabilised by, associated traits in a character complex.

UV SEDs of early-type cluster galaxies: a new look at the UV upturn

NASA Astrophysics Data System (ADS)

Ali, S. S.; Bremer, M. N.; Phillipps, S.; De Propris, R.

2018-05-01

Using GALEX, Ultraviolet Optical Telescope (UVOT), and optical photometry, we explore the prevalence and strength of the Ultraviolet (UV) upturn in the spectra of quiescent early-type galaxies in several nearby clusters. Even for galaxies with completely passive optical colours, there is a large spread in vacuum UV colour consistent with almost all having some UV upturn component. Combining GALEX and UVOT data below 3000 Å, we generate for the first time comparatively detailed UV spectral energy distributions for Coma cluster galaxies. Fitting the UV upturn component with a blackbody, 26 of these show a range of characteristic temperatures (10 000-21 000K) for the UV upturn population. Assuming a single temperature to explain GALEX-optical colours could underestimate the fraction of galaxies with UV upturns and mis-classify some as systems with residual star formation. The UV upturn phenomenon is not an exclusive feature found only in giant galaxies; we identify galaxies with similar (or even bluer) FUV - V colours to the giants with upturns over a range of fainter luminosities. The temperature and strength of the UV upturn are correlated with galaxy mass. Under the plausible hypothesis that the sources of the UV upturn are blue horizontal branch stars, the most likely mechanism for this is the presence of a substantial (between 4 per cent and 20 per cent) Helium-rich (Y > 0.3) population of stars in these galaxies, potentially formed at z ˜ 4 and certainly at z > 2; this plausibly sets a lower limit of {˜ } {0.3- 0.8} × 10^{10} M⊙ to the in situ stellar mass of ˜L* galaxies at this redshift.

Relativistic effects on galaxy redshift samples due to target selection

NASA Astrophysics Data System (ADS)

Alam, Shadab; Croft, Rupert A. C.; Ho, Shirley; Zhu, Hongyu; Giusarma, Elena

2017-10-01

In a galaxy redshift survey, the objects to be targeted for spectra are selected from a photometrically observed sample. The observed magnitudes and colours of galaxies in this parent sample will be affected by their peculiar velocities, through relativistic Doppler and relativistic beaming effects. In this paper, we compute the resulting expected changes in galaxy photometry. The magnitudes of the relativistic effects are a function of redshift, stellar mass, galaxy velocity and velocity direction. We focus on the CMASS sample from the Sloan Digital Sky Survey (SDSS) and Baryon Oscillation Spectroscopic Survey (BOSS), which is selected on the basis of colour and magnitude. We find that 0.10 per cent of the sample (∼585 galaxies) has been scattered into the targeted region of colour-magnitude space by relativistic effects, and conversely 0.09 per cent of the sample (∼532 galaxies) has been scattered out. Observational consequences of these effects include an asymmetry in clustering statistics, which we explore in a companion paper. Here, we compute a set of weights that can be used to remove the effect of modulations introduced into the density field inferred from a galaxy sample. We conclude by investigating the possible effects of these relativistic modulation on large-scale clustering of the galaxy sample.

Pterin pigment granules are responsible for both broadband light scattering and wavelength selective absorption in the wing scales of pierid butterflies

PubMed Central

Morehouse, Nathan I; Vukusic, Peter; Rutowski, Ron

2006-01-01

A small but growing literature indicates that many animal colours are produced by combinations of structural and pigmentary mechanisms. We investigated one such complex colour phenotype: the highly chromatic wing colours of pierid butterflies including oranges, yellows and patterns which appear white to the human eye, but strongly absorb the ultraviolet (UV) wavelengths visible to butterflies. Pierids produce these bright colours using wing scales that contain collections of minute granules. However, to date, no work has directly characterized the molecular composition or optical properties of these granules. We present results that indicate these granules contain pterin pigments. We also find that pterin granules increase light reflection from single wing scales, such that wing scales containing denser granule arrays reflect more light than those with less dense granule collections. As male wing scales contain more pterin granules than those of females, the sexual dichromatism found in many pierid species can be explained by differences in wing scale pterin deposition. Additionally, the colour pattern elements produced by these pterins are known to be important during mating interactions in a number of pierid species. Therefore, we discuss the potential relevance of our results within the framework of sexual selection and colour signal evolution. PMID:17164199

Skin of colour: Characteristics and disease.

PubMed

Zaidi, Zohra

2017-02-01

Skin colour varies from pale white to very dark. Fitzpatrick's skin phototypes are based on the person's skin colour and its response to sun exposure in terms of burning and tanning of the skin. Fitzpatrick's type 1V-V1 is known as the skin of colour and type 1-111 is the fair or white skin. The colour of the skin and texture of the hair are the most apparent phenotype to differentiate the different races; this correlates closely with the geography and ultraviolet radiation of the sun. There are notable differences in skin disease incidence, presentation, and treatment based on skin type. Differences in skin anatomy and physiology between the fair skin and the skin of colour may explain disparities in skin disorders and provide insight into appropriate differences in the management of cutaneous disease. Differences in culture and habits may produce skin lesions unknown to the local physicians. Temperature, humidity and rainfall are closely interwoven with the fauna and flora of the area. Hot and humid climate favours bacterial and fungal infections. Today in this multicultural society due to globalization, a physician has to see patients from all over the globe. There is a need for the physicians to know the diseases of people from different racial and ethnic backgrounds for early diagnosis and treatment.

Examination of molecular mechanism for the enhanced thermal stability of anthocyanins by metal cations and polysaccharides.

PubMed

Tachibana, Noriko; Kimura, Yukihiro; Ohno, Takashi

2014-01-15

Anthocyanins exhibit colour variation over wide pH range but the colour stability is relatively low at the physiological pH. To improve the stability of anthocyanins in neutral to weakly acidic pH region, effects of metal cations and polysaccharides on the colour stability of cyanidin-3-glucoside (C3G) were examined by ultraviolet-visible and resonance Raman spectroscopies. C3G was thermally stabilized by the addition of Fe(3+) but formed aggregation. However, further addition of anionic polysaccharides enhanced the thermal stability of C3G without aggregation. Similar stabilisation was confirmed for delphinidin-3-glucoside (D3G) but not for pelargonidin-3-glucoside. The stability of anthocyanins considerably varied depending on pHs and kinds of metal cations, polysaccharides and buffer molecules. The characteristic resonance Raman bands of C3G-Fe(3+) and D3G-Fe(3+) complexes were significantly affected by the addition of alginate, (18)O/(16)O-isotope substitution, and Fe(2+)/Fe(3+)-replacement. These results suggest that alginate associates with C3G through Fe(3+) to form a stable complex, which enhances the thermal stability of C3G. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of memory load on hemispheric asymmetries of colour memory.

PubMed

Clapp, Wes; Kirk, Ian J; Hausmann, Markus

2007-03-01

Hemispheric asymmetries in colour perception have been a matter of debate for some time. Recent evidence suggests that lateralisation of colour processing may be largely task specific. Here we investigated hemispheric asymmetries during different types and phases of a delayed colour-matching (recognition) memory task. A total of 11 male and 12 female right-handed participants performed colour-memory tasks. The task involved presentation of a set of colour stimuli (encoding), and subsequent indication (forced choice) of which colours in a larger set had previously appeared at the retrieval or recognition phase. The effect of memory load (set size), and the effect of lateralisation at the encoding or retrieval phases were investigated. Overall, the results indicate a right hemisphere advantage in colour processing, which was particularly pronounced in high memory load conditions, and was seen in males rather than female participants. The results suggest that verbal (mnemonic) strategies can significantly affect the magnitude of hemispheric asymmetries in a non-verbal task.

Aqueous two-phase based on ionic liquid liquid-liquid microextraction for simultaneous determination of five synthetic food colourants in different food samples by high-performance liquid chromatography.

PubMed

Sha, Ou; Zhu, Xiashi; Feng, Yanli; Ma, Weixing

2015-05-01

A rapid and effective method of aqueous two-phase systems based on ionic liquid microextraction for the simultaneous determination of five synthetic food colourants (tartrazine, sunset yellow, amaranth, ponceau 4R and brilliant blue) in food samples was established. High-performance liquid chromatography coupled with an ultraviolet detector of variable wavelength was used for the determinations. 1-alkyl-3-methylimidazolium bromide was selected as the extraction reagent. The extraction efficiency of the five colourants in the proposed system is influenced by the types of salts, concentrations of salt and [CnMIM]Br, as well as the extracting time. Under the optimal conditions, the extraction efficiencies for these five colourants were above 95%. The phase behaviours of aqueous two-phase system and extraction mechanism were investigated by UV-vis spectroscopy. This method was applied to the analysis of the five colourants in real food samples with the detection limit of 0.051-0.074 ng/mL. Good spiked recoveries from 93.2% to 98.9% were obtained. Copyright © 2014 Elsevier Ltd. All rights reserved.

Colour and Light Effects on Students' Achievement, Behavior and Physiology.

ERIC Educational Resources Information Center

Wohlfarth, H.

A quasi-experimental non-equivalent control group design was used to investigate the effects of full-spectrum light, prescribed color and light/color combinations, ultra-violet light, and electromagnetic radiation in an elementary school environment. Four schools in the Wetaskiwin School District, Alberta, were involved in the study; three served…

Energy transfer and colour tunability in UV light induced Tm3+/Tb3+/Eu3+: ZnB glasses generating white light emission.

PubMed

Naresh, V; Gupta, Kiran; Parthasaradhi Reddy, C; Ham, Byoung S

2017-03-15

A promising energy transfer (Tm 3+ →Tb 3+ →Eu 3+ ) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm 3+ /Tb 3+ /Eu 3+ ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II) x -[O(-II)] y centres in the ZnB glass matrix. At 360nm (UV) excitation, triply doped Tm 3+ /Tb 3+ /Eu 3+ : ZnB glasses simultaneously shown their characteristic emission bands in blue (454nm: 1 D 2 → 3 F 4 ), green (547nm: 5 D 4 → 7 F 5 ) and red (616nm: 5 D 0 → 7 F 2 ) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb 3+ in ET from Tm 3+ →Eu 3+ was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb 3+ , Eu 3+ ) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening. Copyright © 2016 Elsevier B.V. All rights reserved.

Skylab ultraviolet stellar spectra - A new white dwarf, HD 149499 B

NASA Technical Reports Server (NTRS)

Parsons, S. B.; Wray, J. D.; Benedict, G. F.; Henize, K. G.; Laget, M.

1976-01-01

The letter reports the discovery of a cool star with excess brightness in the vacuum ultraviolet on an objective-prism photograph obtained during the second Skylab mission. This star, HD 149499, is of type K0 V and has a companion with an apparent magnitude of about 11.8; the relatively flat UV spectrum observed at the position of HD 149499 is characteristic of a 10th or 11th magnitude unreddened O- or early B-type star. It is shown that the excess VUV brightness is due to the companion, HD 149499B, which probably lies in the region of the H-R diagram occupied by the hot white dwarfs. Inspection of white dwarf lists indicates that this star is the sixth or seventh brightest white dwarf known. A maximum orbital motion of 0.025 arcsec/yr is estimated along with a period of just under 500 yr.

Reliability of the Raven Coloured Progressive Matrices for Anglo and for Mexican-American Children.

ERIC Educational Resources Information Center

Valencia, Richard R.

1984-01-01

Investigated the internal consistency reliability estimates of the Raven Coloured Progressive Matrices (CPM) for 96 Anglo and Mexican American third-grade boys from low socioeconomic status background. The results showed that the reliability estimates of the CPM for the two ethnic groups were acceptably high and extremely similar in magnitude.…

Superhump and outburst activity of the cataclysmic variable RZ LMi in the U- and optical passbands

NASA Astrophysics Data System (ADS)

Shugarov, S. Y.; Katysheva, N. A.; Chochol, D.; Krushevska, V. N.; Vozyakova, O. V.

2018-05-01

An analysis of the new U,B,V,RC,IC-photometry of the cataclysmic variable RZ LMi obtained in 2016-17 showed the largest (U-B) colour excess in quiescence as well as during the decline of brightness, associated with the outbursts activity. The smallest (U-B) colour excess was found during the brightness increase from the quiescence. In contrast to the (U-B) colour index, the (B-V),(V-RC),(RC-IC) colour indices exhibits the largest colour excesses near the maximum of the outburst and the smallest during the quiescence. The (B-V) colour index showed also a large excess 1-2 days before a minimum. The detailed study of superhumps during the maximum of activity reveals the largest (U-B) colour excess at the time of the minimum brightness of superhumps. The (B-RC) colour index exhibits a similar behaviour, but with a phase shift of +0.1-{+}0.2 period of superhumps. The tracks in two-colour and colour-magnitude diagrams during superoutbursts are compared with the data for other cataclysmic variables during their outbursts as well as with published theoretical calculations.

Widely tunable two-colour seeded free-electron laser source for resonant-pump resonant-probe magnetic scattering

PubMed Central

Ferrari, Eugenio; Spezzani, Carlo; Fortuna, Franck; Delaunay, Renaud; Vidal, Franck; Nikolov, Ivaylo; Cinquegrana, Paolo; Diviacco, Bruno; Gauthier, David; Penco, Giuseppe; Ribič, Primož Rebernik; Roussel, Eleonore; Trovò, Marco; Moussy, Jean-Baptiste; Pincelli, Tommaso; Lounis, Lounès; Manfredda, Michele; Pedersoli, Emanuele; Capotondi, Flavio; Svetina, Cristian; Mahne, Nicola; Zangrando, Marco; Raimondi, Lorenzo; Demidovich, Alexander; Giannessi, Luca; De Ninno, Giovanni; Danailov, Miltcho Boyanov; Allaria, Enrico; Sacchi, Maurizio

2016-01-01

The advent of free-electron laser (FEL) sources delivering two synchronized pulses of different wavelengths (or colours) has made available a whole range of novel pump–probe experiments. This communication describes a major step forward using a new configuration of the FERMI FEL-seeded source to deliver two pulses with different wavelengths, each tunable independently over a broad spectral range with adjustable time delay. The FEL scheme makes use of two seed laser beams of different wavelengths and of a split radiator section to generate two extreme ultraviolet pulses from distinct portions of the same electron bunch. The tunability range of this new two-colour source meets the requirements of double-resonant FEL pump/FEL probe time-resolved studies. We demonstrate its performance in a proof-of-principle magnetic scattering experiment in Fe–Ni compounds, by tuning the FEL wavelengths to the Fe and Ni 3p resonances. PMID:26757813

Theoretical colours and isochrones for some Hubble Space Telescope colour systems

NASA Technical Reports Server (NTRS)

Edvardsson, B.; Bell, R. A.

1989-01-01

Synthetic spectra for effective temperatures of 4000-7250 K, logarithmic surface gravities typical of dwarfs and subgiants, and metallicities from solar values to 0.001 of the solar metallicity were used to derive a grid of synthetic surface brightness magnitudes for 21 of the Hubble Space Telescope Wide Field Camera (WFC) band passes. The absolute magnitudes of these 21 band passes are also obtained for a set of globular cluster isochrones with different helium abundances, metallicities, oxygen abundances, and ages. The usefulness and efficiency of different sets of broad and intermediate bandwidth WFC colors for determining ages and metallicities for globular clusters are evaluated.

Parallel inputs to memory in bee colour vision.

PubMed

Horridge, Adrian

2016-03-01

In the 19(th) century, it was found that attraction of bees to light was controlled by light intensity irrespective of colour, and a few critical entomologists inferred that vision of bees foraging on flowers was unlike human colour vision. Therefore, quite justly, Professor Carl von Hess concluded in his book on the Comparative Physiology of Vision (1912) that bees do not distinguish colours in the way that humans enjoy. Immediately, Karl von Frisch, an assistant in the Zoology Department of the same University of Münich, set to work to show that indeed bees have colour vision like humans, thereby initiating a new research tradition, and setting off a decade of controversy that ended only at the death of Hess in 1923. Until 1939, several researchers continued the tradition of trying to untangle the mechanism of bee vision by repeatedly testing trained bees, but made little progress, partly because von Frisch and his legacy dominated the scene. The theory of trichromatic colour vision further developed after three types of receptors sensitive to green, blue, and ultraviolet (UV), were demonstrated in 1964 in the bee. Then, until the end of the century, all data was interpreted in terms of trichromatic colour space. Anomalies were nothing new, but eventually after 1996 they led to the discovery that bees have a previously unknown type of colour vision based on a monochromatic measure and distribution of blue and measures of modulation in green and blue receptor pathways. Meanwhile, in the 20(th) century, search for a suitable rationalization, and explorations of sterile culs-de-sac had filled the literature of bee colour vision, but were based on the wrong theory.

True and false memory for colour names versus actual colours: support for the visual distinctiveness heuristic in memory for colour information.

PubMed

Eslick, Andrea N; Kostic, Bogdan; Cleary, Anne M

2010-06-01

In a colour variation of the Deese-Roediger-McDermott (DRM) false memory paradigm, participants studied lists of words critically related to a nonstudied colour name (e.g., "blood, cherry, scarlet, rouge ... "); they later showed false memory for the critical colour name (e.g., "red"). Two additional experiments suggest that participants generate colour imagery in response to such colour-related DRM lists. First, participants claim to experience colour imagery more often following colour-related than standard non-colour-related DRM lists; they also rate their colour imagery as more vivid following colour-related lists. Second, participants exhibit facilitative priming for critical colours in a dot selection task that follows words in the colour-related DRM list, suggesting that colour-related DRM lists prime participants for the actual critical colours themselves. Despite these findings, false memory for critical colour names does not extend to the actual colours themselves (font colours). Rather than leading to source confusion about which colours were self-generated and which were studied, presenting the study lists in varied font colours actually worked to reduce false memory overall. Results are interpreted within the framework of the visual distinctiveness hypothesis.

An integrated anaerobic digestion and UV photocatalytic treatment of distillery wastewater.

PubMed

Apollo, Seth; Onyango, Maurice S; Ochieng, Aoyi

2013-10-15

Anaerobic up-flow fixed bed reactor and annular photocatalytic reactor were used to study the efficiency of integrated anaerobic digestion (AD) and ultraviolet (UV) photodegradation of real distillery effluent and raw molasses wastewater (MWW). It was found that UV photodegradation as a stand-alone technique achieved colour removal of 54% and 69% for the distillery and MWW, respectively, with a COD reduction of <20% and a negligible BOD reduction. On the other hand, AD as a single treatment technique was found to be effective in COD and BOD reduction with efficiencies of above 75% and 85%, respectively, for both wastewater samples. However, the AD achieved low colour removal efficiency, with an increase in colour intensity of 13% recorded when treating MWW while a colour removal of 51% was achieved for the distillery effluent. The application of UV photodegradation as a pre-treatment method to the AD process reduced the COD removal and biogas production efficiency. However, an integration in which UV photodegradation was employed as a post-treatment to the AD process achieved high COD removal of above 85% for both wastewater samples, and colour removal of 88% for the distillery effluent. Thus, photodegradation can be employed as a post-treatment technique to an AD system treating distillery effluent for complete removal of the biorecalcitrant and colour imparting compounds. Copyright © 2013 Elsevier B.V. All rights reserved.

Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours. II. The role of convection across the H-R diagram

NASA Astrophysics Data System (ADS)

Kučinskas, A.; Klevas, J.; Ludwig, H.-G.; Bonifacio, P.; Steffen, M.; Caffau, E.

2018-05-01

Aims: We studied the influence of convection on the spectral energy distributions (SEDs), photometric magnitudes, and colour indices of different types of stars across the H-R diagram. Methods: The 3D hydrodynamical CO5BOLD, averaged ⟨3D⟩, and 1D hydrostatic LHD model atmospheres were used to compute SEDs of stars on the main sequence (MS), main sequence turn-off (TO), subgiant branch (SGB), and red giant branch (RGB), in each case at two different effective temperatures and two metallicities, [M/H] = 0.0 and - 2.0. Using the obtained SEDs, we calculated photometric magnitudes and colour indices in the broad-band Johnson-Cousins UBVRI and 2MASS JHKs, and the medium-band Strömgren uvby photometric systems. Results: The 3D-1D differences in photometric magnitudes and colour indices are small in both photometric systems and typically do not exceed ± 0.03 mag. Only in the case of the coolest giants located on the upper RGB are the differences in the U and u bands able reach ≈-0.2 mag at [M/H] = 0.0 and ≈-0.1 mag at [M/H] = -2.0. Generally, the 3D-1D differences are largest in the blue-UV part of the spectrum and decrease towards longer wavelengths. They are also sensitive to the effective temperature and are significantly smaller in hotter stars. Metallicity also plays a role and leads to slightly larger 3D-1D differences at [M/H] = 0.0. All these patterns are caused by a complex interplay between the radiation field, opacities, and horizontal temperature fluctuations that occur due to convective motions in stellar atmospheres. Although small, the 3D-1D differences in the magnitudes and colour indices are nevertheless comparable to or larger than typical photometric uncertainties and may therefore cause non-negligible systematic differences in the estimated effective temperatures.

Colour pairs for constraining the age and metallicity of stellar populations

NASA Astrophysics Data System (ADS)

Li, Zhongmu; Han, Zhanwen

2008-04-01

Using a widely used stellar-population synthesis model, we study the possibility of using pairs of AB system colours to break the well-known stellar age-metallicity degeneracy and to give constraints on two luminosity-weighted stellar-population parameters (age and metallicity). We present the relative age and metallicity sensitivities of the AB system colours that relate to the u,B,g,V,r,R,i, I,z,J,H and K bands, and we quantify the ability of various colour pairs to break the age-metallicity degeneracy. Our results suggest that a few pairs of colours can be used to constrain the above two stellar-population parameters. This will be very useful for exploring the stellar populations of distant galaxies. In detail, colour pairs [(r-K), (u-R)] and [(r-K), (u-r)] are shown to be the best pairs for estimating the luminosity-weighted stellar ages and metallicities of galaxies. They can constrain two stellar-population parameters on average with age uncertainties less than 3.89 Gyr and metallicity uncertainties less than 0.34 dex for typical colour uncertainties. The typical age uncertainties for young populations (age < 4.6 Gyr) and metal-rich populations (Z >= 0.001) are small (about 2.26 Gyr) while those for old populations (age >= 4.6 Gyr) and metal-poor populations (Z < 0.001) are much larger (about 6.88 Gyr). However, the metallicity uncertainties for metal-poor populations (about 0.0024) are much smaller than for other populations (about 0.015). Some other colour pairs can also possibly be used for constraining the two parameters. On the whole, the estimation of stellar-population parameters is likely to be reliable only for early-type galaxies with small colour errors and globular clusters, because such objects contain less dust. In fact, no galaxy is totally dust-free and early-type galaxies are also likely have some dust [e.g. E(B- V) ~ 0.05], which can change the stellar ages by about 2.5 Gyr and metallicities (Z) by about 0.015. When we compare the photometric estimates with previous spectroscopic estimates, we find some differences, especially when comparing the stellar ages determined by two methods. The differences mainly result from the young populations of galaxies. Therefore, it is difficult to obtain the absolute values of stellar ages and metallicities, but the results are useful for obtaining some relative values. In addition, our results suggest that colours relating to both UBVRIJHK and ugriz magnitudes are much better than either UBVRIJHK or ugriz colours for breaking the well-known degeneracy. The results also show that the stellar ages and metallicities of galaxies observed by the Sloan Digital Sky Survey and the Two-Micron All-Sky Survey can be estimated via photometry data. The data are available at the Centre de Données astronomiques de Strabourg (CDS) or on request to the authors. E-mail: zhongmu.li@gmail.com

The eyes and vision of butterflies.

PubMed

Arikawa, Kentaro

2017-08-15

Butterflies use colour vision when searching for flowers. Unlike the trichromatic retinas of humans (blue, green and red cones; plus rods) and honeybees (ultraviolet, blue and green photoreceptors), butterfly retinas typically have six or more photoreceptor classes with distinct spectral sensitivities. The eyes of the Japanese yellow swallowtail (Papilio xuthus) contain ultraviolet, violet, blue, green, red and broad-band receptors, with each ommatidium housing nine photoreceptor cells in one of three fixed combinations. The Papilio eye is thus a random patchwork of three types of spectrally heterogeneous ommatidia. To determine whether Papilio use all of their receptors to see colours, we measured their ability to discriminate monochromatic lights of slightly different wavelengths. We found that Papilio can detect differences as small as 1-2 nm in three wavelength regions, rivalling human performance. We then used mathematical modelling to infer which photoreceptors are involved in wavelength discrimination. Our simulation indicated that the Papilio vision is tetrachromatic, employing the ultraviolet, blue, green and red receptors. The random array of three ommatidial types is a common feature in butterflies. To address the question of how the spectrally complex eyes of butterflies evolved, we studied their developmental process. We have found that the development of butterfly eyes shares its molecular logic with that of Drosophila: the three-way stochastic expression pattern of the transcription factor Spineless determines the fate of ommatidia, creating the random array in Papilio. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

On the use of Gaia magnitudes and new tables of bolometric corrections

NASA Astrophysics Data System (ADS)

Casagrande, L.; VandenBerg, Don A.

2018-06-01

The availability of reliable bolometric corrections and reddening estimates, rather than the quality of parallaxes will be one of the main limiting factors in determining the luminosities of a large fraction of Gaia stars. With this goal in mind, we provide Gaia GBP, G, and GRP synthetic photometry for the entire MARCS grid, and test the performance of our synthetic colours and bolometric corrections against space-borne absolute spectrophotometry. We find indication of a magnitude-dependent offset in Gaia DR2 G magnitudes, which must be taken into account in high accuracy investigations. Our interpolation routines are easily used to derive bolometric corrections at desired stellar parameters, and to explore the dependence of Gaia photometry on Teff, log g, {[Fe/H]}, [α /{Fe}] and E(B - V). Gaia colours for the Sun and Vega, and Teff-dependent extinction coefficients, are also provided.

The DART Imaging And CaT Survey of the Fornax Dwarf Spheroidal Galaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Battaglia, Giuseppina; Tolstoy, E.; Helmi, A.

2006-08-28

As part of the DART project we have used the ESO/2.2m Wide Field Imager in conjunction with the VLT/FLAMES* GIRAFFE spectrograph to study the detailed properties of the resolved stellar population of the Fornax dwarf spheroidal galaxy out to and beyond its tidal radius. Fornax dSph has had a complicated evolution and contains significant numbers of young, intermediate age and old stars. We investigate the relation between these different components by studying their photometric, kinematic and abundance distributions. We re-derived the structural parameters of the Fornax dwarf spheroidal using our wide field imaging covering the galaxy out to its tidalmore » radius, and analyzed the spatial distribution of the Fornax stars of different ages as selected from Colour-Magnitude Diagram analysis. We have obtained accurate velocities and metallicities from spectra in the Ca II triplet wavelength region for 562 Red Giant Branch stars which have velocities consistent with membership in Fornax dwarf spheroidal. We have found evidence for the presence of at least three distinct stellar components: a young population (few 100 Myr old) concentrated in the center of the galaxy, visible as a Main Sequence in the Colour-Magnitude Diagram; an intermediate age population (2-8 Gyr old); and an ancient population (> 10Gyr), which are distinguishable from each other kinematically, from the metallicity distribution and in the spatial distribution of stars found in the Colour-Magnitude Diagram. From our spectroscopic analysis we find that the ''metal rich'' stars ([Fe/H] > -1.3) show a less extended and more concentrated spatial distribution, and display a colder kinematics than the ''metal poor'' stars ([Fe/H] < -1.3). There is tentative evidence that the ancient stellar population in the center of Fornax does not exhibit equilibrium kinematics. This could be a sign of a relatively recent accretion of external material, such as the merger of another galaxy or other means of gas accretion at some point in the fairly recent past, consistent with other recent evidence of substructure (Coleman et al. 2004, 2005).« less

On the physical nature of six galactic open cluster candidates

NASA Astrophysics Data System (ADS)

Piatti, A. E.; Clariá, J. J.; Ahumada, A. V.

We present CCD UBVI_(KC) photometry in the fields of the unstudied open cluster (OC) candidates Haffner 3, Haffner 5, NGC 2368, Haffner 25, Hogg 3 and Hogg 4. Our analysis shows that none of these objects are genuine OCs since no clear main sequences or other typical features can be seen in their colour-magnitude and colour-colour diagrams. Star counts performed within and outside the OC candidate fields not only support these results but also suggest that these objects are not OC remnants. A detailed version of this work can be seen in New Astronomy, 16, 161 (2011).

Modelling a man-portable air-defence (MANPAD) system with a rosette scan two-colour infrared (IR) and ultraviolet (UV) seeker

NASA Astrophysics Data System (ADS)

Kumar, Devinder; Smith, Leon; Richardson, Mark A.; Ayling, Richard; Barlow, Nick

2014-10-01

The Ultraviolet (UV) band of the electromagnetic (EM) spectrum has the potential to be used as the host medium for the operation of guided weapons. Unlike in the Infrared (IR), a target propelled by an air breathing jet engine produces no detectable radiation in the UV band, and is opaque to the background UV produced by the Sun. Successful engineering of spectral airborne IR countermeasures (CM) against existing two colour IR seekers has encouraged missile counter-countermeasure (CCM) designers to utilise the silhouette signature of an aircraft in the UV as a means of distinguishing between a true target and a flare CM. In this paper we describe the modelling process of a dual band IR and UV rosette scan seeker using CounterSim, a missile engagement and countermeasure simulation software package developed by Chemring Countermeasures Ltd. Results are shown from various simulated engagements of the dual band MANPAD with a C-130 Hercules modelled by Chemring Countermeasures. These results have been used to estimate the aircrafts' vulnerability to this MANPAD threat. A discussion on possible future optical countermeasures against dual band IR-UV seekers is given in conclusion to the simulation results.

Galaxy and Mass Assembly (GAMA): ugriz galaxy luminosity functions

NASA Astrophysics Data System (ADS)

Loveday, J.; Norberg, P.; Baldry, I. K.; Driver, S. P.; Hopkins, A. M.; Peacock, J. A.; Bamford, S. P.; Liske, J.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Hill, D. T.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H. R.; Phillipps, S.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

2012-02-01

Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from Phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z < 0.1, we find that blue galaxies, defined according to a magnitude-dependent but non-evolving colour cut, are reasonably well fitted over a range of more than 10 magnitudes by simple Schechter functions in all bands. Red galaxies, and the combined blue plus red sample, require double power-law Schechter functions to fit a dip in their LF faintwards of the characteristic magnitude M* before a steepening faint end. This upturn is at least partly due to dust-reddened disc galaxies. We measure the evolution of the galaxy LF over the redshift range 0.002 < z < 0.5 both by using a parametric fit and by measuring binned LFs in redshift slices. The characteristic luminosity L* is found to increase with redshift in all bands, with red galaxies showing stronger luminosity evolution than blue galaxies. The comoving number density of blue galaxies increases with redshift, while that of red galaxies decreases, consistent with prevailing movement from blue cloud to red sequence. As well as being more numerous at higher redshift, blue galaxies also dominate the overall luminosity density beyond redshifts z≃ 0.2. At lower redshifts, the luminosity density is dominated by red galaxies in the riz bands, and by blue galaxies in u and g.

Association between ultraviolet radiation, skin sun sensitivity and risk of pancreatic cancer.

PubMed

Tran, Bich; Whiteman, David C; Webb, Penelope M; Fritschi, Lin; Fawcett, Jonathan; Risch, Harvey A; Lucas, Robyn; Pandeya, Nirmala; Schulte, Annaka; Neale, Rachel E

2013-12-01

Ecological studies showing an inverse association between pancreatic cancer incidence and mortality and levels of ultraviolet radiation (UVR), suggest that higher levels of sun exposure may reduce risks of pancreatic cancer but there has been only one individual-level study that examined this issue. We aimed to examine the association between pancreatic cancer and markers of exposure to solar UVR, namely skin type, treatment of skin lesions, ambient UVR and time outdoors on work days. We used data from an Australian case-control study. Location at birth, residential location during adulthood, outdoors work, history of skin lesion treatment and sensitivity of the skin to the sun were obtained by questionnaire. We limited the analyses to Caucasians who answered the questionnaire about UVR (controls=589/711 recruited; cases=496/705 recruited). We used NASA's Total Ozone Mapping Spectrometer to estimate ambient UVR. Being born in or living in areas of higher ambient UVR (compared to lower ambient UVR) was associated with about 30-40% lower risk of pancreatic cancer. People with fair skin colour had 47% lower risk of pancreatic cancer than those with dark skin colour (95% CI 0.37-0.75). There was some suggestion of increased risk with increased average number of hours spent outside at work. This study suggests that people with light skin colour or those born or living in areas of high ambient UVR have lower risk of pancreatic cancer. Our analysis supports an association between UVR and pancreatic cancer, possibly mediated through production of vitamin D. Copyright © 2013 Elsevier Ltd. All rights reserved.

Melanocortin MC1 receptor in human genetics and model systems

PubMed Central

Beaumont, Kimberley A.; Wong, Shu S.; Ainger, Stephen A.; Liu, Yan Yan; Patel, Mira P.; Millhauser, Glenn L.; Smith, Jennifer J.; Alewood, Paul F.; Leonard, J. Helen; Sturm, Richard A.

2011-01-01

The melanocortin MC1 receptor is a G -protein coupled receptor expressed in melanocytes of the skin and hair and is known for its key role in regulation of human pigmentation. Melanocortin MC1 receptor activation after ultraviolet radiation exposure results in a switch from the red/yellow pheomelanin to the brown/black eumelanin pigment synthesis within cutaneous melanocytes; this pigment is then transferred to the surrounding keratinocytes of the skin. The increase in melanin maturation and uptake results in tanning of the skin, providing a physical protection of skin cells from ultraviolet radiation induced DNA damage. Melanocortin MC 1 receptor polymorphism is widespread within the Caucasian population and some variant alleles are associated with red hair colour, fair skin, poor tanning and increased risk of skin cancer. Here we will discuss the use of mouse coat colour models, human genetic association studies, and in vitro cell culture studies to determine the complex functions of the melanocortin MC1 receptor and the molecular mechanisms underlying the association between melanocortin MC1 receptor variant alleles and the red hair colour phenotype. Recent research indicates that melanocortin MC1 receptor has many non-pigmentary functions, and that the increased risk of skin cancer conferred by melanocortin MC1 receptor variant alleles is to some extent independent of pigmentation phenotypes. The use of new transgenic mouse models, the study of novel melanocortin MC1 receptor response genes and the use of more advanced human skin models such as 3D skin reconstruction may provide key elements in understanding the pharmacogenetics of human melanocortin MC1 receptor polymorphism . PMID:21199646

UV-Vis microspectrophotometry as a method of differentiation between cotton fibre evidence coloured with reactive dyes

NASA Astrophysics Data System (ADS)

Was-Gubala, Jolanta; Starczak, Roza

2015-05-01

The main purposes of this study was to assess the usefulness of microspectrophotometry (MSP), both in the ultraviolet (UV) and visible (Vis) range for discriminating single cotton fibres dyed with reactive dyes coming from the same manufacturer, as well as the possibility of evaluation of the concentration of dye in an examine fibre. This study utilised woven cotton fabrics dyed with different concentrations of one-compound reactive dyes with the commercial name Cibacron® (at present Novacron®) as the focus of the MSP analysis. The spectra were recorded in the UV-Vis range between 200 and 800 nm, in transmission mode. The results from this study illustrated that all of the analysed cotton samples dyed with reactive dyes were distinguishable between each other with the use of MSP, mostly in the visible, and also in ultraviolet range. The limit for applied MSP techniques was 0.18% of the concentration of a dye in the textile sample. The results indicate that based on the absorbance measurements for fibres constituting e.g. forensic traces it was not possible to estimate the concentration of the dye in the fibre because Beer's law did not obey. The intra-sample, and inter- sample variation, as well as dichroism effect in a case of a cotton fibres dyed with reactive dye were observed. On the basis of the results obtained for each analysed cotton sample, it was concluded that there was no correlation between colour uniformity in cotton fabric (changes in lightness, red/green and yellow/blue colour) and concentration of the reactive dye.

The AKARI FU-HYU galaxy evolution program: first results from the GOODS-N field

NASA Astrophysics Data System (ADS)

Pearson, C. P.; Serjeant, S.; Negrello, M.; Takagi, T.; Jeong, W.-S.; Matsuhara, H.; Wada, T.; Oyabu, S.; Lee, H. M.; Im, M. S.

2010-05-01

The AKARI FU-HYU mission program carried out mid-infrared imaging of several well studied Spitzer fields preferentially selecting fields already rich in multi-wavelength data from radio to X-ray wavelengths filling in the wavelength desert between the Spitzer IRAC and MIPS bands. We present the initial results for the FU-HYU survey in the GOODS-N field. We utilize the supreme multiwavelength coverage in the GOODS-N field to produce a multiwavelength catalogue from infrared to ultraviolet wavelengths, containing more than 4393 sources, including photometric redshifts. Using the FU-HYU catalogue we present colour-colour diagrams that map the passage of PAH features through our observation bands. We find that the longer mid-infrared bands from AKARI (IRC-L18W 18 micron band) and Spitzer (MIPS24 24 micron band) provide an accurate measure of the total MIR emission of the sources and therefore their probable total mid-infrared luminosity. We also find that colours incorporating the AKARI IRC-S11 11 micron band produce a bimodal distribution where an excess at 11 microns preferentially selects moderate redshift star-forming galaxies. These powerful colour-colour diagnostics are further used as tools to extract anomalous colour populations, in particular a population of Silicate Break galaxies from the GOODS-N field showing that dusty starbursts can be selected of specific redshift ranges (z = 1.2-1.6) by mid-infrared drop-out techniques. The FU-HYU catalogue will be made publically available to the astronomical community.

IUE and ground-based observations of the Hubble-Sandage variables in M31 and M33

NASA Technical Reports Server (NTRS)

Blaha, C.; Dodorico, S.; Gull, T. R.; Benvenuti, P.; Humphreys, R. M.

1984-01-01

Ultraviolet spectra were obtained from the International Ultraviolet Explorer for the brightest Hubble-Sandage (H-S) variables in M31 and M33. The ultraviolet fluxes were then used in combination with ground-based visual and infrared photometry to determine the energy distributions, luminosities, and temperatures of these stars. When corrected for interstellar extinction, the integrated energy distributions yield the total luminosities and blackbody temperatures of the H-S variables. The resulting bolometric magnitudes and temperatures confirm that these peculiar stars are indeed very luminous, hot stars. They occupy the same regions of the bolometric magnitude vs temperature diagram as Eta Car and P Cyg in the Galaxy and S Dor in the LMC.

An isochrone data base and a rapid model for stellar population synthesis

NASA Astrophysics Data System (ADS)

Li, Zhongmu; Han, Zhanwen

2008-06-01

We first presented an isochrone data base that can be widely used for stellar population synthesis studies and colour-magnitude diagram (CMD) fitting. The data base consists of the isochrones of both single-star and binary-star simple stellar populations (ss-SSPs and bs-SSPs). The ranges for the age and metallicity of populations are 0-15 Gyr and 0.0001-0.03, respectively. All data are available for populations with two widely used initial mass functions (IMFs), that is, Salpeter IMF and Chabrier IMF. The uncertainty caused by the data base (about 0.81 per cent) is designed to be smaller than those caused by the Hurley code and widely used stellar spectra libraries (e.g. BaSeL 3.1) when it is used for stellar population synthesis. Based on the isochrone data base, we then built a rapid stellar population synthesis (RPS) model and calculated the high-resolution (0.3-Å) integrated spectral energy distributions, Lick indices and colour indices for bs-SSPs and ss-SSPs. In particular, we calculated the UBVRIJHKLM colours, ugriz colours and some composite colours that consist of magnitudes on different systems. These colours are useful for disentangling the well-known stellar age-metallicity degeneracy according to our previous work. As an example for applying the isochrone data base for CMD fitting, we fitted the CMDs of two star clusters (M67 and NGC1868) and obtained their distance moduli, colour excesses, stellar metallicities and ages. The results showed that the isochrones of bs-SSPs are closer to those of real star clusters. It suggests that we should take the effects of binary interactions into account in stellar population synthesis. We also discussed on the limitations of the application of the isochrone data base and the results of the RPS model. All the data are available at the CDS or on request to the authors. E-mail: zhongmu.li@gmail.com

Impact of ultraviolet radiation treatments on the physicochemical properties, antioxidants, enzyme activity and microbial load in freshly prepared hand pressed strawberry juice.

PubMed

Bhat, Rajeev; Stamminger, Rainer

2015-07-01

Freshly prepared, hand-pressed strawberry fruit juice was exposed to ultraviolet radiation (254 nm) at room temperature (25 ℃ ± 1 ℃) for 15, 30 and 60 min with 0 min serving as control. Results revealed decrease in pH, total soluble solids and titratable acidity, while colour parameters (L*, a* and b* values) and clarity of juice (% transmittance) increased significantly. All the results corresponded to exposure time to ultraviolet radiation. Bioactive compounds (total phenolics, ascorbic acid and anthocyanins) decreased along with a recorded reduction in polyphenol oxidase enzyme and 1,1-diphenyl-2-picryl hydrazyl radical scavenging activities, which were again dependent on exposure time. Results on the microbial studies showed significant reduction by 2-log cycles in aerobic plate count as well as in total yeast and mould counts. Though negative results were observed for certain parameters, this is the first time it was endeavoured to demonstrate the impact of ultraviolet radiation radiation on freshly prepared, hand-pressed strawberries juice. © The Author(s) 2014.

Photometric catalogue for stars in Selected Areas and other fields inthe RGU-system (X). Photometry of fields in and near to the Milky Way: Anticenter 5, Carina (IC 2581), Centaurus III, Aquila II, Cassiopeia(NGC 7654).

NASA Astrophysics Data System (ADS)

Becker, W.; Fenkart, R. P.; Spaenhauer, A.; Alfaro, E. A.; Kandemir, G.; Karaali, S.; Fang, C.; Garcia-Pelayo, J. M.; Steppe, H.; Topaktas, L.

The tenth volume of the Basle Photometric Catalogues contains the G-magnitudes, as well as the long- (G-R) and short-wave (U-G) colour indices of the stars in five galactic fields. Additionally, data as obtained from the interpretationof the two-colour diagrams are given, i.e.: if the star in question has been identified as a main-sequence star of either population, or asa late-type giant, or if it is blended on the photographic plates of one or more colours.

Enhanced effect of temporal variation of the fine structure constant and the strong interaction in 229Th.

PubMed

Flambaum, V V

2006-09-01

The relative effects of the variation of the fine structure constant alpha = e2/variant Planck's over 2pi c and the dimensionless strong interaction parameter m(q)/LambdaQCD are enhanced by 5-6 orders of magnitude in a very narrow ultraviolet transition between the ground and the first excited states in the 229Th nucleus. It may be possible to investigate this transition with laser spectroscopy. Such an experiment would have the potential of improving the sensitivity to temporal variation of the fundamental constants by many orders of magnitude.

Innate colour preference, individual learning and memory retention in the ant Camponotus blandus.

PubMed

Yilmaz, Ayse; Dyer, Adrian G; Rössler, Wolfgang; Spaethe, Johannes

2017-09-15

Ants are a well-characterized insect model for the study of visual learning and orientation, but the extent to which colour vision is involved in these tasks remains unknown. We investigated the colour preference, learning and memory retention of Camponotus blandus foragers under controlled laboratory conditions. Our results show that C. blandus foragers exhibit a strong innate preference for ultraviolet (UV, 365 nm) over blue (450 nm) and green (528 nm) wavelengths. The ants can learn to discriminate 365 nm from either 528 nm or 450 nm, independent of intensity changes. However, they fail to discriminate between 450 nm and 528 nm. Modelling of putative colour spaces involving different numbers of photoreceptor types revealed that colour discrimination performance of individual ants is best explained by dichromacy, comprising a short-wavelength (UV) receptor with peak sensitivity at about 360 nm, and a long-wavelength receptor with peak sensitivity between 470 nm and 560 nm. Foragers trained to discriminate blue or green from UV light are able to retain the learned colour information in an early mid-term (e-MTM), late mid-term (l-MTM), early long-term (e-LTM) and late long-term (l-LTM) memory from where it can be retrieved after 1 h, 12 h, 24 h, 3 days and 7 days after training, indicating that colour learning may induce different memory phases in ants. Overall, our results show that ants can use chromatic information in a way that should promote efficient foraging in complex natural environments. © 2017. Published by The Company of Biologists Ltd.

How Bees Discriminate a Pattern of Two Colours from Its Mirror Image

PubMed Central

Horridge, Adrian

2015-01-01

A century ago, in his study of colour vision in the honeybee (Apis mellifera), Karl von Frisch showed that bees distinguish between a disc that is half yellow, half blue, and a mirror image of the same. Although his inference of colour vision in this example has been accepted, some discrepancies have prompted a new investigation of the detection of polarity in coloured patterns. In new experiments, bees restricted to their blue and green receptors by exclusion of ultraviolet could learn patterns of this type if they displayed a difference in green contrast between the two colours. Patterns with no green contrast required an additional vertical black line as a landmark. Tests of the trained bees revealed that they had learned two inputs; a measure and the retinotopic position of blue with large field tonic detectors, and the measure and position of a vertical edge or line with small-field phasic green detectors. The angle between these two was measured. This simple combination was detected wherever it occurred in many patterns, fitting the definition of an algorithm, which is defined as a method of processing data. As long as they excited blue receptors, colours could be any colour to human eyes, even white. The blue area cue could be separated from the green receptor modulation by as much as 50°. When some blue content was not available, the bees learned two measures of the modulation of the green receptors at widely separated vertical edges, and the angle between them. There was no evidence that the bees reconstructed the lay-out of the pattern or detected a tonic input to the green receptors. PMID:25617892

Machine Vision-Based Measurement Systems for Fruit and Vegetable Quality Control in Postharvest.

PubMed

Blasco, José; Munera, Sandra; Aleixos, Nuria; Cubero, Sergio; Molto, Enrique

Individual items of any agricultural commodity are different from each other in terms of colour, shape or size. Furthermore, as they are living thing, they change their quality attributes over time, thereby making the development of accurate automatic inspection machines a challenging task. Machine vision-based systems and new optical technologies make it feasible to create non-destructive control and monitoring tools for quality assessment to ensure adequate accomplishment of food standards. Such systems are much faster than any manual non-destructive examination of fruit and vegetable quality, thus allowing the whole production to be inspected with objective and repeatable criteria. Moreover, current technology makes it possible to inspect the fruit in spectral ranges beyond the sensibility of the human eye, for instance in the ultraviolet and near-infrared regions. Machine vision-based applications require the use of multiple technologies and knowledge, ranging from those related to image acquisition (illumination, cameras, etc.) to the development of algorithms for spectral image analysis. Machine vision-based systems for inspecting fruit and vegetables are targeted towards different purposes, from in-line sorting into commercial categories to the detection of contaminants or the distribution of specific chemical compounds on the product's surface. This chapter summarises the current state of the art in these techniques, starting with systems based on colour images for the inspection of conventional colour, shape or external defects and then goes on to consider recent developments in spectral image analysis for internal quality assessment or contaminant detection.

Coherent modulation of stimulus colour can affect visually induced self-motion perception.

PubMed

Nakamura, Shinji; Seno, Takeharu; Ito, Hiroyuki; Sunaga, Shoji

2010-01-01

The effects of dynamic colour modulation on vection were investigated to examine whether perceived variation of illumination affects self-motion perception. Participants observed expanding optic flow which simulated their forward self-motion. Onset latency, accumulated duration, and estimated magnitude of the self-motion were measured as indices of vection strength. Colour of the dots in the visual stimulus was modulated between white and red (experiment 1), white and grey (experiment 2), and grey and red (experiment 3). The results indicated that coherent colour oscillation in the visual stimulus significantly suppressed the strength of vection, whereas incoherent or static colour modulation did not affect vection. There was no effect of the types of the colour modulation; both achromatic and chromatic modulations turned out to be effective in inhibiting self-motion perception. Moreover, in a situation where the simulated direction of a spotlight was manipulated dynamically, vection strength was also suppressed (experiment 4). These results suggest that observer's perception of illumination is critical for self-motion perception, and rapid variation of perceived illumination would impair the reliabilities of visual information in determining self-motion.

Enhanced ultraviolet photoconductivity in porous GaN prepared by metal-assisted electroless etching

NASA Astrophysics Data System (ADS)

Guo, X. Y.; Williamson, T. L.; Bohn, P. W.

2006-10-01

The ultraviolet photoconductivity of porous GaN (PGaN) produced by Pt-assisted electroless etching has been investigated. The photoresponse of PGaN prepared from highly doped GaN ( n>1018 cm) shows enhanced ( 15×) magnitude and faster decay of persistent photoconductivity relative to bulk crystalline (CGaN), suggesting advantages for PGaN in photodetector applications. A space charge model for changes in photoconductivity is used to explain these observations. Heightened defect density in the etched material plays an important role in the enhanced photoconductivity in PGaN. Flux-dependent optical quenching (OQ) behavior, linked to the presence of metastable states, is also observed in PGaN as in CGaN.

CCD UBVRI photometry of NGC 6811

NASA Astrophysics Data System (ADS)

Yontan, T.; Bilir, S.; Bostancı, Z. F.; Ak, T.; Karaali, S.; Güver, T.; Ak, S.; Duran, Ş.; Paunzen, E.

2015-02-01

We present the results of CCD UBVRI observations of the open cluster NGC 6811 obtained on 18th July 2012 with the 1 m telescope at the TÜBİTAK National Observatory (TUG). Using these photometric results, we determine the structural and astrophysical parameters of the cluster. The mean photometric uncertainties are better than 0.02 mag in the V magnitude and B- V, V- R, and V- I colour indices to about 0.03 mag for U- B among stars brighter than magnitude V=18. Cluster member stars were separated from the field stars using the Galaxia model of Sharma et al. (2011) together with other techniques. The core radius of the cluster is found to be r c =3.60 arcmin. The astrophysical parameters were determined simultaneously via Bayesian statistics using the colour-magnitude diagrams V versus B- V, V versus V- I, V versus V- R, and V versus R- I of the cluster. The resulting most likely parameters were further confirmed using independent methods, removing any possible degeneracies. The colour excess, distance modulus, metallicity and the age of the cluster are determined simultaneously as E( B- V)=0.05±0.01 mag, μ=10.06±0.08 mag, [ M/ H]=-0.10±0.01 dex and t=1.00±0.05 Gyr, respectively. Distances of five red clump stars which were found to be members of the cluster further confirm our distance estimation.

Influence of induced colour centres on the frequency - angular spectrum of a light bullet of mid-IR radiation in lithium fluoride

NASA Astrophysics Data System (ADS)

Chekalin, S. V.; Kompanets, V. O.; Dormidonov, A. E.; Kandidov, V. P.

2017-04-01

The influence of the occurrence of a structure consisting of long-lived colour centres, formed in an LiF crystal upon filamentation of femtosecond mid-IR radiation, on the supercontinuum characteristics is investigated. With an increase in the number of incident pulses, the length and transverse size of the structure of colour centres induced in LiF increase, and the supercontinuum spectrum in the short-wavelength region is markedly transformed due to the occurrence of the waveguide propagation regime, absorption, and scattering of radiation from the newly formed structure of colour centres. Under these conditions, the intensity of the anti-Stokes wing decreases by two orders of magnitude after several tens of pulses. Spectral components arise in the visible range, the angular divergence of which increases with increasing wavelength.

Theoretical colours and isochrones for some Hubble Space Telescope colour systems. II

NASA Technical Reports Server (NTRS)

Paltoglou, G.; Bell, R. A.

1991-01-01

A grid of synthetic surface brightness magnitudes for 14 bandpasses of the Hubble Space Telescope Faint Object Camera is presented, as well as a grid of UBV, uvby, and Faint Object Camera surface brightness magnitudes derived from the Gunn-Stryker spectrophotometric atlas. The synthetic colors are used to examine the transformations between the ground-based Johnson UBV and Stromgren uvby systems and the Faint Object Camera UBV and uvby. Two new four-color systems, similar to the Stromgren system, are proposed for the determination of abundance, temperature, and surface gravity. The synthetic colors are also used to calculate color-magnitude isochrones from the list of theoretical tracks provided by VandenBerg and Bell (1990). It is shown that by using the appropriate filters it is possible to minimize the dependence of this color difference on metallicity. The effects of interstellar reddening on various Faint Object Camera colors are analyzed as well as the observational requirements for obtaining data of a given signal-to-noise for each of the 14 bandpasses.

Ultraviolet signals in birds are special.

PubMed

Hausmann, Franziska; Arnold, Kathryn E; Marshall, N Justin; Owens, Ian P F

2003-01-07

Recent behavioural experiments have shown that birds use ultraviolet (UV)-reflective and fluorescent plumage as cues in mate choice. It remains controversial, however, whether such UV signals play a special role in sexual communication, or whether they are part of general plumage coloration. We use a comparative approach to test for a general association between sexual signalling and either UV-reflective or fluorescent plumage. Among the species surveyed, 72% have UV colours and there is a significant positive association between UV reflectance and courtship displays. Among parrots (Psittaciformes), 68% of surveyed species have fluorescent plumage, and again there is a strong positive association between courtship displays and fluorescence. These associations are not artefacts of the plumage used in courtship displays, being generally more 'colourful' because there is no association between display and colours lacking UV reflectance or fluorescence. Equally, these associations are not phylogenetic artefacts because all results remain unchanged when families or genera, rather than species, are used as independent data points. We also find that, in parrots, fluorescent plumage is usually found adjacent to UV-reflective plumage. Using a simple visual model to examine one parrot, the budgerigar Melopsittacus undulatus, we show that the juxtaposition of UV-reflective and fluorescent plumage leads to a 25-fold increase in chromatic contrast to the budgerigar's visual system. Taken together, these results suggest that signals based on UV contrast are of special importance in the context of active sexual displays. We review briefly six hypotheses on why this may be the case: suitability for short-range signalling; high contrast with backgrounds; invisibility to predators; exploitation of pre-existing sensory biases; advertisement of feather structure; and amplification of behavioural signals.

UV-Vis microspectrophotometry as a method of differentiation between cotton fibre evidence coloured with reactive dyes.

PubMed

Was-Gubala, Jolanta; Starczak, Roza

2015-05-05

The main purposes of this study was to assess the usefulness of microspectrophotometry (MSP), both in the ultraviolet (UV) and visible (Vis) range for discriminating single cotton fibres dyed with reactive dyes coming from the same manufacturer, as well as the possibility of evaluation of the concentration of dye in an examine fibre. This study utilised woven cotton fabrics dyed with different concentrations of one-compound reactive dyes with the commercial name Cibacron® (at present Novacron®) as the focus of the MSP analysis. The spectra were recorded in the UV-Vis range between 200 and 800nm, in transmission mode. The results from this study illustrated that all of the analysed cotton samples dyed with reactive dyes were distinguishable between each other with the use of MSP, mostly in the visible, and also in ultraviolet range. The limit for applied MSP techniques was 0.18% of the concentration of a dye in the textile sample. The results indicate that based on the absorbance measurements for fibres constituting e.g. forensic traces it was not possible to estimate the concentration of the dye in the fibre because Beer's law did not obey. The intra-sample, and inter- sample variation, as well as dichroism effect in a case of a cotton fibres dyed with reactive dye were observed. On the basis of the results obtained for each analysed cotton sample, it was concluded that there was no correlation between colour uniformity in cotton fabric (changes in lightness, red/green and yellow/blue colour) and concentration of the reactive dye. Copyright © 2015 Elsevier B.V. All rights reserved.

Ultraviolet signals in birds are special.

PubMed Central

Hausmann, Franziska; Arnold, Kathryn E; Marshall, N Justin; Owens, Ian P F

2003-01-01

Recent behavioural experiments have shown that birds use ultraviolet (UV)-reflective and fluorescent plumage as cues in mate choice. It remains controversial, however, whether such UV signals play a special role in sexual communication, or whether they are part of general plumage coloration. We use a comparative approach to test for a general association between sexual signalling and either UV-reflective or fluorescent plumage. Among the species surveyed, 72% have UV colours and there is a significant positive association between UV reflectance and courtship displays. Among parrots (Psittaciformes), 68% of surveyed species have fluorescent plumage, and again there is a strong positive association between courtship displays and fluorescence. These associations are not artefacts of the plumage used in courtship displays, being generally more 'colourful' because there is no association between display and colours lacking UV reflectance or fluorescence. Equally, these associations are not phylogenetic artefacts because all results remain unchanged when families or genera, rather than species, are used as independent data points. We also find that, in parrots, fluorescent plumage is usually found adjacent to UV-reflective plumage. Using a simple visual model to examine one parrot, the budgerigar Melopsittacus undulatus, we show that the juxtaposition of UV-reflective and fluorescent plumage leads to a 25-fold increase in chromatic contrast to the budgerigar's visual system. Taken together, these results suggest that signals based on UV contrast are of special importance in the context of active sexual displays. We review briefly six hypotheses on why this may be the case: suitability for short-range signalling; high contrast with backgrounds; invisibility to predators; exploitation of pre-existing sensory biases; advertisement of feather structure; and amplification of behavioural signals. PMID:12590772

Milky Way demographics with the VVV survey. I. The 84-million star colour-magnitude diagram of the Galactic bulge

NASA Astrophysics Data System (ADS)

Saito, R. K.; Minniti, D.; Dias, B.; Hempel, M.; Rejkuba, M.; Alonso-García, J.; Barbuy, B.; Catelan, M.; Emerson, J. P.; Gonzalez, O. A.; Lucas, P. W.; Zoccali, M.

2012-08-01

Context. The Milky Way (MW) bulge is a fundamental Galactic component for understanding the formation and evolution of galaxies, in particular our own. The ESO Public Survey VISTA Variables in the Vía Láctea is a deep near-IR survey mapping the Galactic bulge and southern plane. Particularly for the bulge area, VVV is covering ~315 deg2. Data taken during 2010 and 2011 covered the entire bulge area in the JHKs bands. Aims: We used VVV data for the whole bulge area as a single and homogeneous data set to build for the first time a single colour - magnitude diagram (CMD) for the entire Galactic bulge. Methods: Photometric data in the JHKs bands were combined to produce a single and huge data set containing 173 150 467 sources in the three bands, for the ~315 deg2 covered by VVV in the bulge. Selecting only the data points flagged as stellar, the total number of sources is 84 095 284. Results: We built the largest colour-magnitude diagrams published up to date, containing 173.1+ million sources for all data points, and more than 84.0 million sources accounting for the stellar sources only. The CMD has a complex shape, mostly owing to the complexity of the stellar population and the effects of extinction and reddening towards the Galactic centre. The red clump (RC) giants are seen double in magnitude at b ~ -8° -10°, while in the inner part (b ~ -3°) they appear to be spreading in colour, or even splitting into a secondary peak. Stellar population models show the predominance of main-sequence and giant stars. The analysis of the outermost bulge area reveals a well-defined sequence of late K and M dwarfs, seen at (J - Ks) ~ 0.7-0.9 mag and Ks ≳ 14 mag. Conclusions: The interpretation of the CMD yields important information about the MW bulge, showing the fingerprint of its structure and content. We report a well-defined red dwarf sequence in the outermost bulge, which is important for the planetary transit searches of VVV. The double RC in magnitude seen in the outer bulge is the signature of the X-shaped MW bulge, while the spreading of the RC in colour, and even its splitting into a secondary peak, are caused by reddening effects. The region around the Galactic centre is harder to interpret because it is strongly affected by reddening and extinction. Based on observations taken within the ESO VISTA Public Survey VVV, Programme ID 179.B-2002.The VVV survey data are available through the ESO archive http://www.eso.org/sci/archive.html

Seeing red primes tomato: evidence for comparable priming from colour and colour name primes to semantically related word targets.

PubMed

Nijboer, Tanja C W; van Zandvoort, Martine J E; de Haan, Edward H F

2006-12-01

There is ample evidence that an independent processing stream exists that subserves the perception and appreciation of colour. Neurophysiological research has identified separate brain mechanisms for the processing of wavelength and colour, and neuropsychological studies have revealed selective colour disorders, such as achromatopsia, colour agnosia, and colour anomia. The aim of the present study is to investigate whether the perception of colour may, despite its independent processing, influence other cognitive functions. Specifically, we investigate the possibility that the perception of a colour influences higher order processes such as the activation of semantically related concepts. We designed an associative priming task involving a colour prime (e.g. a red patch or the word RED) and a lexical decision response to a semantically related ('tomato' vs. 'timato') or unrelated ('grass' vs. 'griss') word target. The results of this experiment indicate that there is comparable facilitation of accessing colour-related semantics through the perception of a colour or the reading of a colour name. This suggests that colour has a direct effect on higher order level, cognitive processing. These results are discussed in terms of current models of colour processing.

A portable explosive detector based on fluorescence quenching of pyrene deposited on coloured wax-printed μPADs.

PubMed

Taudte, Regina Verena; Beavis, Alison; Wilson-Wilde, Linzi; Roux, Claude; Doble, Philip; Blanes, Lucas

2013-11-07

A new technique for the detection of explosives has been developed based on fluorescence quenching of pyrene on paper-based analytical devices (μPADs). Wax barriers were generated (150 °C, 5 min) using ten different colours. Magenta was found as the most suitable wax colour for the generation of the hydrophobic barriers with a nominal width of 120 μm resulting in fully functioning hydrophobic barriers. One microliter of 0.5 mg mL(-1) pyrene dissolved in an 80:20 methanol-water solution was deposited on the hydrophobic circle (5 mm diameter) to produce the active microchip device. Under ultra-violet (UV) illumination, ten different organic explosives were detected using the μPAD, with limits of detection ranging from 100-600 ppm. A prototype of a portable battery operated instrument using a 3 W power UV light-emitting-diode (LED) (365 nm) and a photodiode sensor was also built and evaluated for the successful automatic detection of explosives and potential application for field-based screening.

UV-Green Iridescence Predicts Male Quality during Jumping Spider Contests

PubMed Central

Lim, Matthew L. M.; Li, Daiqin

2013-01-01

Animal colour signals used in intraspecies communications can generally be attributed to a composite effect of structural and pigmentary colours. Notably, the functional role of iridescent coloration that is ‘purely’ structural (i.e., absence of pigments) is poorly understood. Recent studies reveal that iridescent colorations can reliably indicate individual quality, but evidence of iridescence as a pure structural coloration indicative of male quality during contests and relating to an individual’s resource-holding potential (RHP) is lacking. In age- and size-controlled pairwise male-male contests that escalate from visual displays of aggression to more costly physical fights, we demonstrate that the ultraviolet-green iridescence of Cosmophasis umbratica predicts individual persistence and relates to RHP. Contest initiating males exhibited significantly narrower carapace band separation (i.e., relative spectral positions of UV and green hues) than non-initiators. Asymmetries in carapace and abdomen brightness influenced overall contest duration and escalation. As losers retreated upon having reached their own persistence limits in contests that escalated to physical fights, losers with narrower carapace band separation were significantly more persistence. We propose that the carapace UV-green iridescence of C. umbratica predicts individual persistence and is indicative of a male’s RHP. As the observed UV-green hues of C. umbratica are ‘pure’ optical products of a multilayer reflector system, we suggest that intrasexual variations in the optical properties of the scales’ chitin-air-chitin microstructures are responsible for the observed differences in carapace band separations. PMID:23573210

UV-green iridescence predicts male quality during jumping spider contests.

PubMed

Lim, Matthew L M; Li, Daiqin

2013-01-01

Animal colour signals used in intraspecies communications can generally be attributed to a composite effect of structural and pigmentary colours. Notably, the functional role of iridescent coloration that is 'purely' structural (i.e., absence of pigments) is poorly understood. Recent studies reveal that iridescent colorations can reliably indicate individual quality, but evidence of iridescence as a pure structural coloration indicative of male quality during contests and relating to an individual's resource-holding potential (RHP) is lacking. In age- and size-controlled pairwise male-male contests that escalate from visual displays of aggression to more costly physical fights, we demonstrate that the ultraviolet-green iridescence of Cosmophasis umbratica predicts individual persistence and relates to RHP. Contest initiating males exhibited significantly narrower carapace band separation (i.e., relative spectral positions of UV and green hues) than non-initiators. Asymmetries in carapace and abdomen brightness influenced overall contest duration and escalation. As losers retreated upon having reached their own persistence limits in contests that escalated to physical fights, losers with narrower carapace band separation were significantly more persistence. We propose that the carapace UV-green iridescence of C. umbratica predicts individual persistence and is indicative of a male's RHP. As the observed UV-green hues of C. umbratica are 'pure' optical products of a multilayer reflector system, we suggest that intrasexual variations in the optical properties of the scales' chitin-air-chitin microstructures are responsible for the observed differences in carapace band separations.

Long-term optical flux and colour variability in quasars

NASA Astrophysics Data System (ADS)

Sukanya, N.; Stalin, C. S.; Jeyakumar, S.; Praveen, D.; Dhani, Arnab; Damle, R.

2016-02-01

We have used optical V and R band observations from the Massive Compact Halo Object (MACHO) project on a sample of 59 quasars behind the Magellanic clouds to study their long term optical flux and colour variations. These quasars, lying in the redshift range of 0.2 < z < 2.8 and having apparent V band magnitudes between 16.6 and 20.1 mag, have observations ranging from 49 to 1353 epochs spanning over 7.5 yr with frequency of sampling between 2 to 10 days. All the quasars show variability during the observing period. The normalised excess variance (Fvar) in V and R bands are in the range 0.2% < FVvar < 1.6% and 0.1% < FRvar < 1.5% respectively. In a large fraction of the sources, Fvar is larger in the V band compared to the R band. From the z-transformed discrete cross-correlation function analysis, we find that there is no lag between the V and R band variations. Adopting the Markov Chain Monte Carlo (MCMC) approach, and properly taking into account the correlation between the errors in colours and magnitudes, it is found that the majority of sources show a bluer when brighter trend, while a minor fraction of quasars show the opposite behaviour. This is similar to the results obtained from another two independent algorithms, namely the weighted linear least squares fit (FITEXY) and the bivariate correlated errors and intrinsic scatter regression (BCES). However, the ordinary least squares (OLS) fit, normally used in the colour variability studies of quasars, indicates that all the quasars studied here show a bluer when brighter trend. It is therefore very clear that the OLS algorithm cannot be used for the study of colour variability in quasars.

The colour-magnitude relation of globular clusters in Centaurus and Hydra. Constraints on star cluster self-enrichment with a link to massive Milky Way globular clusters

NASA Astrophysics Data System (ADS)

Fensch, J.; Mieske, S.; Müller-Seidlitz, J.; Hilker, M.

2014-07-01

Aims: We investigate the colour-magnitude relation of metal-poor globular clusters, the so-called blue tilt, in the Hydra and Centaurus galaxy clusters and constrain the primordial conditions for star cluster self-enrichment. Methods: We analyse U,I photometry for about 2500 globular clusters in the central regions of Hydra and Centaurus, based on VLT/FORS1 data. We measure the relation between mean colour and luminosity for the blue and red subpopulation of the globular cluster samples. We convert these relations into mass-metallicity space and compare the obtained GC mass-metallicity relation with predictions from the star cluster self-enrichment model by Bailin & Harris (2009, ApJ, 695, 1082). For this we include effects of dynamical and stellar evolution and a physically well motivated primordial mass-radius scaling. Results: We obtain a mass-metallicity scaling of Z ∝ M0.27 ± 0.05 for Centaurus GCs and Z ∝ M0.40 ± 0.06 for Hydra GCs, consistent with the range of observed relations in other environments. We find that the GC mass-metallicity relation already sets in at present-day masses of a few and is well established in the luminosity range of massive MW clusters like ω Centauri. The inclusion of a primordial mass-radius scaling of star clusters significantly improves the fit of the self-enrichment model to the data. The self-enrichment model accurately reproduces the observed relations for average primordial half-light radii rh ~ 1-1.5 pc, star formation efficiencies f⋆ ~ 0.3-0.4, and pre-enrichment levels of [Fe/H] - 1.7 dex. The slightly steeper blue tilt for Hydra can be explained either by a ~30% smaller average rh at fixed f⋆ ~ 0.3, or analogously by a ~20% smaller f⋆ at fixed rh ~ 1.5 pc. Within the self-enrichment scenario, the observed blue tilt implies a correlation between GC mass and width of the stellar metallicity distribution. We find that this implied correlation matches the trend of width with GC mass measured in Galactic GCs, including extreme cases like ω Centauri and M 54. Conclusions: First, we found that a primordial star cluster mass-radius relation provides a significant improvement to the self-enrichment model fits. Second we show that broadened metallicity distributions as found in some massive MW globular clusters may have arisen naturally from self-enrichment processes, without the need of a dwarf galaxy progenitor.

Controlling upconversion nanocrystals for emerging applications

NASA Astrophysics Data System (ADS)

Zhou, Bo; Shi, Bingyang; Jin, Dayong; Liu, Xiaogang

2015-11-01

Lanthanide-doped upconversion nanocrystals enable anti-Stokes emission with pump intensities several orders of magnitude lower than required by conventional nonlinear optical techniques. Their exceptional properties, namely large anti-Stokes shifts, sharp emission spectra and long excited-state lifetimes, have led to a diversity of applications. Here, we review upconversion nanocrystals from the perspective of fundamental concepts and examine the technical challenges in relation to emission colour tuning and luminescence enhancement. In particular, we highlight the advances in functionalization strategies that enable the broad utility of upconversion nanocrystals for multimodal imaging, cancer therapy, volumetric displays and photonics.

An overview of the extreme ultraviolet explorer and its scientific program

NASA Technical Reports Server (NTRS)

Malina, Roger F.; Finley, David S.; Jelinsky, Patrick; Vallerga, John; Bowyer, Stuart

1987-01-01

NASA's Extreme Ultraviolet Explorer (EUVE) will carry out an all-sky survey from 8 to 90 nm in four bandpasses; the limiting sensitivity will be between 2 to 3 orders of magnitude fainter than the hot white dwarf HZ 43. A deep survey will also be carried out along the ecliptic which will have a limiting sensitivity of 1 to 2 orders of magnitude fainter than the all-sky survey in the bandpass from 8 to 50 nm. The payload also includes a spectrometer which will be used to observe the brighter sources found in the surveys with a spectral resolution of 1 to 2 A.

30 Doradus - Ultraviolet and optical stellar photometry

NASA Technical Reports Server (NTRS)

Hill, Jesse K.; Bohlin, Ralph C.; Cheng, Kwang-Ping; Fanelli, Michael N.; Hintzen, Paul; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.; Stecher, Theodore P.

1993-01-01

Ultraviolet Imaging Telescope (UIT) UV magnitudes in four bands, together with optical B magnitudes, are presented for up to 314 early-type stars located in a 9.7 x 9.7 arcmin field centered on R136. The magnitudes have an rms uncertainty estimated at 0.10 mag from a comparison between the UIT magnitudes and the IUE spectra. Spectral types and E(B-V) color excesses are estimated. The mean color excesses following the two extinction curves agree well with the predictions of the two-component extinction model of Fitzpatrick and Savage (1984). However, the degree of nebular extinction is found to vary systematically by large amounts over the 30 Dor field. The minimum of nebular extinction in the central parts of the nebula suggests that dust has been expelled from this region by stellar winds. It is suggested that the form of the UV extinction curve can be understood as a consequence of the evolutionary state of the stellar population responsible for making the dust grains.

Influence of tropospheric ozone control on exposure to ultraviolet radiation at the surface.

PubMed

Madronich, Sasha; Wagner, Mark; Groth, Philip

2011-08-15

Improving air quality by reducing ambient ozone (O(3)) will likely lower O(3) concentrations throughout the troposphere and increase the transmission of solar ultraviolet (UV) radiation to the surface. The changes in surface UV radiation between two control scenarios (nominally 84 and 70 ppb O(3) for summer 2020) in the Eastern two-thirds of the contiguous U.S. are estimated, using tropospheric O(3) profiles calculated with a chemistry-transport model (Community Multi-Scale Air Quality, CMAQ) as inputs to a detailed model of the transfer of solar radiation through the atmosphere (tropospheric ultraviolet-visible, TUV) for clear skies, weighed for the wavelengths known to induce sunburn and skin cancer. Because the incremental emission controls differ according to region, strong spatial variability in O(3) reductions and in corresponding UV radiation increments is seen. The geographically averaged UV increase is 0.11 ± 0.03%, whereas the population-weighted increase is larger, 0.19 ± 0.06%, because O(3) reductions are greater in more densely populated regions. These relative increments in exposure are non-negligible given the already high incidence of UV-related health effects, but are lower by an order of magnitude or more than previous estimates.

Using digital colour to increase the realistic appearance of SEM micrographs of bloodstains.

PubMed

Hortolà, Policarp

2010-10-01

Although in the scientific-research literature the micrographs from scanning electron microscopes (SEMs) are usually displayed in greyscale, the potential of colour resources provided by the SEM-coupled image-acquiring systems and, subsidiarily, by image-manipulation free softwares deserves be explored as a tool for colouring SEM micrographs of bloodstains. After acquiring greyscale SEM micrographs of a (dark red to the naked eye) human blood smear on grey chert, they were manually obtained in red tone using both the SEM-coupled image-acquiring system and an image-manipulation free software, as well as they were automatically generated in thermal tone using the SEM-coupled system. Red images obtained by the SEM-coupled system demonstrated lower visual-discrimination capability than the other coloured images, whereas those in red generated by the free software rendered better magnitude of scopic information than the red images generated by the SEM-coupled system. Thermal-tone images, although were further from the real sample colour than the red ones, not only increased their realistic appearance over the greyscale images, but also yielded the best visual-discrimination capability among all the coloured SEM micrographs, and fairly enhanced the relief effect of the SEM micrographs over both the greyscale and the red images. The application of digital colour by means of the facilities provided by an SEM-coupled image-acquiring system or, when required, by an image-manipulation free software provides a user-friendly, quick and inexpensive way of obtaining coloured SEM micrographs of bloodstains, avoiding to do sophisticated, time-consuming colouring procedures. Although this work was focused on bloodstains, well probably other monochromatic or quasi-monochromatic samples are also susceptible of increasing their realistic appearance by colouring them using the simple methods utilized in this study.

Sensory matched filters.

PubMed

Warrant, Eric J

2016-10-24

As animals move through their environments they are subjected to an endless barrage of sensory signals. Of these, some will be of utmost importance, such as the tell-tale aroma of a potential mate, the distinctive appearance of a vital food source or the unmistakable sound of an approaching predator. Others will be less important. Indeed some will not be important at all. There are, for instance, wide realms of the sensory world that remain entirely undetected, simply because an animal lacks the physiological capacity to detect and analyse the signals that characterise this realm. Take ourselves for example: we are completely insensitive to the Earth's magnetic field, a sensory cue of vital importance as a compass for steering the long distance migration of animals as varied as birds, lobsters and sea turtles. We are also totally oblivious to the rich palette of ultraviolet colours that exist all around us, colours seen by insects, crustaceans, birds, fish and lizards (in fact perhaps by most animals). Nor can we hear the ultrasonic sonar pulses emitted by bats in hot pursuit of flying insect prey. The simple reason for these apparent deficiencies is that we either lack the sensory capacity entirely (as in the case of magnetoreception) or that our existing senses are incapable of detecting specific ranges of the stimulus (such as the ultraviolet wavelength range of light). Copyright © 2016 Elsevier Ltd. All rights reserved.

The effect of colour on children's cognitive performance.

PubMed

Brooker, Alice; Franklin, Anna

2016-06-01

The presence of red appears to hamper adults' cognitive performance relative to other colours (see Elliot & Maier, 2014, Ann. Rev. Psychol. 65, 95). Here, we investigate whether colour affects cognitive performance in 8- and 9-year-olds. Children completed a battery of tasks once in the presence of a coloured screen that was one of eight colours and once in the presence of a grey screen. Performance was assessed for each colour relative to the grey baseline, and differences across colours were compared. We find a significant difference in performance across colours, with significantly worse performance in the presence of red than grey. The effect of colour did not significantly interact with task. The findings suggest that colour can affect children's cognitive performance and that there is a detrimental effect of red. Findings are related to the adult literature and implications for educational contexts are discussed. © 2015 The British Psychological Society.

Catalogue of UV sources in the Galaxy

NASA Astrophysics Data System (ADS)

Beitia-Antero, L.; Gómez de Castro, A. I.

2017-03-01

The Galaxy Evolution Explorer (GALEX) ultraviolet (UV) database contains the largest photometric catalogue in the ultraviolet range; as a result GALEX photometric bands, Near UV band (NUV) and the Far UV band (FUV), have become standards. Nevertheless, the GALEX catalogue does not include bright UV sources due to the high sensitivity of its detectors, neither sources in the Galactic plane. In order to extend the GALEX database for future UV missions, we have obtained synthetic FUV and NUV photometry using the database of UV spectra generated by the International Ultraviolet Explorer (IUE). This database contains 63,755 spectra in the low dispersion mode (λ / δ λ ˜ 300) obtained during its 18-year lifetime. For stellar sources in the IUE database, we have selected spectra with high Signal-To-NoiseRatio (SNR) and computed FUV and NUV magnitudes using the GALEX transmission curves along with the conversion equations between flux and magnitudes provided by the mission. Besides, we have performed variability tests to determine whether the sources were variable (during the IUE observations). As a result, we have generated two different catalogues: one for non-variable stars and another one for variable sources. The former contains FUV and NUV magnitudes, while the latter gives the basic information and the FUV magnitude for each observation. The consistency of the magnitudes has been tested using White Dwarfs contained in both GALEX and IUE samples. The catalogues are available through the Centre des Donées Stellaires. The sources are distributed throughout the whole sky, with a special coverage of the Galactic plane.

An optical imaging study of 0.4 ≤ z ≤ 0.8 quasar host galaxies . II. Analysis and interpretation

NASA Astrophysics Data System (ADS)

Örndahl, E.; Rönnback, J.

2005-11-01

We performed optical imaging of 102 radio-loud and radio-quiet quasars at z=0.4{-}0.8, of which 91 fields were found suitable for host galaxy analysis after the deselection of saturated and otherwise flawed images. The data sets were obtained mainly in the R band, but also in the V and I or Gunn i band, and were presented in Rönnback et al.(1996, MNRAS, 283, 282) and Örndahl et al. (2003, A&A, 404, 883). In this paper we combine the two above-mentioned samples and also separately discuss additional hosts, extracted from data taken by Wold et al. (2000, MNRAS, 316, 267; 2001, MNRAS, 323, 231). The joint sample forms a sizeable fraction of the to-date total number of observed sources at intermediate redshifts and increases the number of resolved radio-quiet hosts at z>0.4 considerably. Equal numbers of radio-loud and radio-quiet objects were observed, resulting in a detection rate of 79% for the radio-loud hosts and 66% for the radio-quiet hosts. Profile fitting could only be carried out for a minority of the sample, but it results in predominantly elliptical morphologies. This is consistent with the mean values of the axial ratios, for which we find b/a⪆0.8 for both radio-quiet and radio-loud hosts, just as in the case of normal elliptical galaxies. The mean absolute magnitudes of the radio-loud and radio-quiet hosts is M_R=-23.5 in both cases. This similarity between the mean magnitudes of the two types of host galaxy is also seen in the other imaged bands. While the radio-loud host absolute R magnitudes are correlated with redshift, only a weak trend of the same sort is seen for the radio-quiet host magnitudes. Note, however, that the sample is not fully resolved and that the detection limit, in combination with the relationship between host and nuclear luminosity, may conspire in creating the illusion of an upturn in magnitude. The average nucleus-to-host galaxy luminosity ratios of the radio-loud and radio-quiet objects do not differ significantly in any band, nor is the difference between the average luminosity ratios of flat spectrum and steep spectrum radio-loud quasars larger than 1.5σ. Thus, no effect of beaming (as expected in the unifying scheme) is seen. The colours of both radio-loud and radio-quiet host galaxies are found to be as blue as present-day late-type spirals and starburst galaxies. These blue colours are most likely due neither to galaxy evolution over the range, which only gives rise to a colour shift of 0.2 mag, nor to scattered nuclear light, since colours determined from annular apertures yield very similar results. Since close companions in projection are not uncommon (and a few sources even exhibit tidal tail-like features and other signs of interaction), ongoing star formation is a reasonable explanation of the blue host colours. As multiple-band imaging primarily was carried out for quasars showing indications of the presence of a host galaxy, the colour analysis results are valid for host galaxies which are large, bright, have low nucleus-to-host luminosity ratios, and/or display large scale disturbances, but cannot however safely be generalised to hold for the quasar host galaxy population at intermediate redshift as a whole.

Stability assessment of lycopene microemulsion prepared using tomato industrial waste against various processing conditions.

PubMed

Amiri-Rigi, Atefeh; Abbasi, Soleiman

2017-11-01

Green separation techniques are growing at a greater rate than solvent extraction as a result of the constant consumer drive to 'go natural'. Considering the increasing evidence of the health benefits of lycopene and massive tomato industrial waste, in the present study, lycopene was extracted from tomato industrial waste using microemulsion technique and its mean droplet size and size distribution was determined. Moreover, the effects of pasteurization, sterilization, freeze-thaw cycles and ultraviolet (UV) irradiation on the thermodynamic stability, turbidity and lycopene concentration of the lycopene microemulsion were monitored. Freeze-thaw cycles, pasteurization and short exposure to UV irradiation showed no or negligible influence on lycopene content and turbidity of the microemulsion. However, long exposure to UV (260 min) reduced the lycopene content and turbidity by 34% and 10%, respectively. HHST (higher-heat shorter-time) and sterilization also reduced lycopene content (25%) and increased turbidity (32%). The lycopene microemulsion showed satisfactory stability over a process where its monodispersity and nanosize could be of potential advantage to the food and related industries. Regarding the carcinogenicity of synthetic colourants, potential applications of the lycopene microemulsion include in soft drinks and minced meat, which would result in a better colour and well-documented health-promoting qualities. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Observations of the peculiar object MWC 560 in outburst

NASA Technical Reports Server (NTRS)

Michalitsianos, A. G.; Maran, S. P.; Oliversen, R. J.; Bopp, B.; Kontizas, E.

1991-01-01

The results of ultraviolet spectroscopy, photoelectric photometry, and supplemental high-resolution H(alpha) spectroscopy of a photometric outburst of MWC 560 are discussed. Ultraviolet spectra are shown to be consistent with the ejection of an optically thick shell that produced strong absorption blends of Fe II and Cr II. The velocities reported exceed by far those previously found in symbiotic stars or recurrent novas. In addition to the variable high-velocity system of broad absorption features, a relatively stable system of Mg II, Mg I, Fe II, Cr II, and other ionic absorptions is observed. It is pointed out that the spectroscopic phenomena in MWC 560 resemble those found in XX Ophiuchi, but the velocities in the MWC 560 are an order of magnitude higher than those found in XX Oph.

Visual awareness of objects and their colour.

PubMed

Pilling, Michael; Gellatly, Angus

2011-10-01

At any given moment, our awareness of what we 'see' before us seems to be rather limited. If, for instance, a display containing multiple objects is shown (red or green disks), when one object is suddenly covered at random, observers are often little better than chance in reporting about its colour (Wolfe, Reinecke, & Brawn, Visual Cognition, 14, 749-780, 2006). We tested whether, when object attributes (such as colour) are unknown, observers still retain any knowledge of the presence of that object at a display location. Experiments 1-3 involved a task requiring two-alternative (yes/no) responses about the presence or absence of a colour-defined object at a probed location. On this task, if participants knew about the presence of an object at a location, responses indicated that they also knew about its colour. A fourth experiment presented the same displays but required a three-alternative response. This task did result in a data pattern consistent with participants' knowing more about the locations of objects within a display than about their individual colours. However, this location advantage, while highly significant, was rather small in magnitude. Results are compared with those of Huang (Journal of Vision, 10(10, Art. 24), 1-17, 2010), who also reported an advantage for object locations, but under quite different task conditions.

Near-infrared study of new embedded clusters in the Carina complex

NASA Astrophysics Data System (ADS)

Oliveira, R. A. P.; Bica, E.; Bonatto, C.

2018-05-01

We analyse the nature of a sample of stellar overdensities that we found projected on the Carina complex. This study is based on the Two Micron All Sky Survey photometry and involves the photometry decontamination of field stars, elaboration of intrinsic colour-magnitude diagrams [CMDs; J × (J - Ks)], colour-colour diagrams (J - H) × (H - Ks), and radial density profiles, in order to determine the structure and the main astrophysical parameters of the best candidates. The verification of an overdensity as an embedded cluster requires a CMD consistent with a PMS content and MS stars, if any. From these results, we are able to verify if they are, in fact, embedded clusters. The results were, in general, rewarding: in a sample of 101 overdensities, the analysis provided 15 candidates, of which three were previously catalogued as clusters (CCCP-Cl 16, Treasure Chest, and FSR 1555), and the 12 remaining are discoveries that provided significant results, with ages not above 4.5 Myr and distances compatible with the studied complex. The resulting values for the differential reddening of most candidates were relatively high, confirming that these clusters are still (partially or fully) embedded in the surrounding gas and dust, as a rule within a shell. Histograms with the distribution of the masses, ages, and distances were also produced, to give an overview of the results. We conclude that all the 12 newly found embedded clusters are related to the Carina complex.

Lack of tumour pigmentation in conjunctival melanoma is associated with light iris colour and worse prognosis.

PubMed

Brouwer, Niels J; Marinkovic, Marina; Luyten, Gregorius P M; Shields, Carol L; Jager, Martine J

2018-05-18

To investigate whether differences in iris colour, skin colour and tumour pigmentation are related to clinical outcome in conjunctival melanoma. Data of 70 patients with conjunctival melanoma from the Leiden University Medical Center (Leiden, The Netherlands) and 374 patients from the Wills Eye Hospital (Philadephia, USA) were reviewed. The relation between iris colour, skin colour and tumour pigmentation versus clinical parameters and outcome was investigated using univariate and multivariate regression analyses. A light iris colour (blue, grey, green) was present in 261 (59%) patients and a dark colour (hazel, brown) in 183 (41%). A low tumour pigmentation was detected in 130 (40%) and a high pigmentation in 197 (60%) patients. Low tumour pigmentation was associated with light iris colour (p=0.021) but not related to skin colour (p=0.92). In univariate analysis, neither iris nor skin colour was related to clinical outcome, while a low tumour pigmentation was related to metastasis formation (HR 2.37, p=0.004) and death (HR 2.42, p=0.020). In multivariate analysis, low tumour pigmentation was related to the development of recurrences (HR 1.63, p=0.043), metastasis formation (HR 2.48, p=0.004) and death (HR 2.60, p=0.014). Lightly pigmented tumours occurred especially in individuals with lightly coloured irises. While iris colour or skin colour was not significantly related to clinical outcome, a low tumour pigmentation was related to a worse outcome in patients with conjunctival melanoma. The amount and type of melanin in conjunctival melanocytes may be involved in the pathogenesis and behaviour of selected conjunctival melanoma. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Population gradient in the Sextans dSph: comprehensive mapping of a dwarf galaxy by Suprime-Cam

NASA Astrophysics Data System (ADS)

Okamoto, S.; Arimoto, N.; Tolstoy, E.; Jablonka, P.; Irwin, M. J.; Komiyama, Y.; Yamada, Y.; Onodera, M.

2017-05-01

We present the deep and wide V and Ic photometry of the Sextans dwarf spheroidal galaxy (dSph) taken by the Suprime-Cam imager on the Subaru Telescope, which extends out to the tidal radius. The colour-magnitude diagram (CMD) reaches two magnitudes below the main-sequence (MS) turn-off, showing a steep red giant branch, a blue and a red horizontal branch (BHB and RHB, respectively), a sub-giant branch (SGB), an MS and blue stragglers (BSs). We construct the radial profile of each evolutionary phase and demonstrate that blue HB stars are more spatially extended, while red HB stars are more centrally concentrated than the other components. The colour distribution of SGB stars also varies with the galactocentric distance; the inner SGB stars shift bluer than those in the outskirts. The radial differences in the CMD morphology indicate the existence of the age gradient. The relatively younger stars (˜10 Gyr) are more centrally concentrated than the older ones (˜13 Gyr). The spatial contour maps of stars in different age bins also show that the younger population has a higher concentration and higher ellipticity than the older one. We also detect the centrally concentrated bright BS stars, the number of which is consistent with the idea that a part of these stars belongs to the remnant of a disrupted star cluster discovered in the previous spectroscopic studies.

Evaluation of Staining-Dependent Colour Changes in Resin Composites Using Principal Component Analysis

PubMed Central

Manojlovic, D.; Lenhardt, L.; Milićević, B.; Antonov, M.; Miletic, V.; Dramićanin, M. D.

2015-01-01

Colour changes in Gradia Direct™ composite after immersion in tea, coffee, red wine, Coca-Cola, Colgate mouthwash, and distilled water were evaluated using principal component analysis (PCA) and the CIELAB colour coordinates. The reflection spectra of the composites were used as input data for the PCA. The output data (scores and loadings) provided information about the magnitude and origin of the surface reflection changes after exposure to the staining solutions. The reflection spectra of the stained samples generally exhibited lower reflection in the blue spectral range, which was manifested in the lower content of the blue shade for the samples. Both analyses demonstrated the high staining abilities of tea, coffee, and red wine, which produced total colour changes of 4.31, 6.61, and 6.22, respectively, according to the CIELAB analysis. PCA revealed subtle changes in the reflection spectra of composites immersed in Coca-Cola, demonstrating Coca-Cola’s ability to stain the composite to a small degree. PMID:26450008

Evaluation of Staining-Dependent Colour Changes in Resin Composites Using Principal Component Analysis.

PubMed

Manojlovic, D; Lenhardt, L; Milićević, B; Antonov, M; Miletic, V; Dramićanin, M D

2015-10-09

Colour changes in Gradia Direct™ composite after immersion in tea, coffee, red wine, Coca-Cola, Colgate mouthwash, and distilled water were evaluated using principal component analysis (PCA) and the CIELAB colour coordinates. The reflection spectra of the composites were used as input data for the PCA. The output data (scores and loadings) provided information about the magnitude and origin of the surface reflection changes after exposure to the staining solutions. The reflection spectra of the stained samples generally exhibited lower reflection in the blue spectral range, which was manifested in the lower content of the blue shade for the samples. Both analyses demonstrated the high staining abilities of tea, coffee, and red wine, which produced total colour changes of 4.31, 6.61, and 6.22, respectively, according to the CIELAB analysis. PCA revealed subtle changes in the reflection spectra of composites immersed in Coca-Cola, demonstrating Coca-Cola's ability to stain the composite to a small degree.

Impact of shortwave ultraviolet (UV-C) radiation on the antioxidant activity of thyme (Thymus vulgaris L.).

PubMed

Dogu-Baykut, Esra; Gunes, Gurbuz; Decker, Eric Andrew

2014-08-15

Thyme is a good source of antioxidant compounds but it can be contaminated by microorganisms. An experimental fluid bed ultraviolet (UV) reactor was designed for microbial decontamination of thyme samples and the effect of shortwave ultraviolet light (UV-C) radiation on antioxidant properties of thyme was studied. Samples were exposed to UV-C radiation for 16 or 64 min. UV-C treatment led to 1.04 and 1.38 log CFU/g reduction of total aerobic mesophilic bacteria (TAMB) counts. Hunter a(∗) value was the most sensitive colour parameter during UV-C treatment. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of extracts was not significantly affected by UV-C. Addition of thyme extracts at 0.15 and 0.3 μmol GAE/ml emulsion delayed the formation of lipid hydroperoxides and headspace hexanal in the 5.0%(wt) corn oil-in-water emulsion from 4 to 9 and 14 days, respectively. No significant changes in oxidation rates were observed between UV-C treated and untreated samples at same concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

A photometrically and spectroscopically confirmed population of passive spiral galaxies

NASA Astrophysics Data System (ADS)

Fraser-McKelvie, Amelia; Brown, Michael J. I.; Pimbblet, Kevin A.; Dolley, Tim; Crossett, Jacob P.; Bonne, Nicolas J.

2016-10-01

We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z < 0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption-line spectra with 4000 Å breaks consistent with an average luminosity-weighted age of 2.3 Gyr. Our photometric and integral field spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.

Spatially modulated structural colour in bird feathers.

PubMed

Parnell, Andrew J; Washington, Adam L; Mykhaylyk, Oleksandr O; Hill, Christopher J; Bianco, Antonino; Burg, Stephanie L; Dennison, Andrew J C; Snape, Mary; Cadby, Ashley J; Smith, Andrew; Prevost, Sylvain; Whittaker, David M; Jones, Richard A L; Fairclough, J Patrick A; Parker, Andrew R

2015-12-21

Eurasian Jay (Garrulus glandarius) feathers display periodic variations in the reflected colour from white through light blue, dark blue and black. We find the structures responsible for the colour are continuous in their size and spatially controlled by the degree of spinodal phase separation in the corresponding region of the feather barb. Blue structures have a well-defined broadband ultra-violet (UV) to blue wavelength distribution; the corresponding nanostructure has characteristic spinodal morphology with a lengthscale of order 150 nm. White regions have a larger 200 nm nanostructure, consistent with a spinodal process that has coarsened further, yielding broader wavelength white reflectance. Our analysis shows that nanostructure in single bird feather barbs can be varied continuously by controlling the time the keratin network is allowed to phase separate before mobility in the system is arrested. Dynamic scaling analysis of the single barb scattering data implies that the phase separation arrest mechanism is rapid and also distinct from the spinodal phase separation mechanism i.e. it is not gelation or intermolecular re-association. Any growing lengthscale using this spinodal phase separation approach must first traverse the UV and blue wavelength regions, growing the structure by coarsening, resulting in a broad distribution of domain sizes.

Spatially modulated structural colour in bird feathers

PubMed Central

Parnell, Andrew J.; Washington, Adam L.; Mykhaylyk, Oleksandr O.; Hill, Christopher J.; Bianco, Antonino; Burg, Stephanie L.; Dennison, Andrew J. C.; Snape, Mary; Cadby, Ashley J.; Smith, Andrew; Prevost, Sylvain; Whittaker, David M.; Jones, Richard A. L.; Fairclough, J. Patrick. A.; Parker, Andrew R.

2015-01-01

Eurasian Jay (Garrulus glandarius) feathers display periodic variations in the reflected colour from white through light blue, dark blue and black. We find the structures responsible for the colour are continuous in their size and spatially controlled by the degree of spinodal phase separation in the corresponding region of the feather barb. Blue structures have a well-defined broadband ultra-violet (UV) to blue wavelength distribution; the corresponding nanostructure has characteristic spinodal morphology with a lengthscale of order 150 nm. White regions have a larger 200 nm nanostructure, consistent with a spinodal process that has coarsened further, yielding broader wavelength white reflectance. Our analysis shows that nanostructure in single bird feather barbs can be varied continuously by controlling the time the keratin network is allowed to phase separate before mobility in the system is arrested. Dynamic scaling analysis of the single barb scattering data implies that the phase separation arrest mechanism is rapid and also distinct from the spinodal phase separation mechanism i.e. it is not gelation or intermolecular re-association. Any growing lengthscale using this spinodal phase separation approach must first traverse the UV and blue wavelength regions, growing the structure by coarsening, resulting in a broad distribution of domain sizes. PMID:26686280

Prediction of texture and colour of dry-cured ham by visible and near infrared spectroscopy using a fiber optic probe.

PubMed

García-Rey, R M; García-Olmo, J; De Pedro, E; Quiles-Zafra, R; Luque de Castro, M D

2005-06-01

The potential of visible and near infrared spectroscopy to predict texture and colour of dry-cured ham samples was investigated. Sensory evaluation was performed on 117 boned and cross-sectioned dry-cured ham samples. Slices of approximate thickness 4cm were cut, vacuum-packaged and kept under frozen storage until spectral analysis. Then, Biceps femoris muscle from the thawed slices was taken and scanned (400-2200nm) using a fiber optic probe. The exploratory analysis using principal component analysis shows that there are two ham groups according to the appearance or not of defects. Then, a K nearest neighbours was used to classify dry-cured hams into defective or no defective classes. The overall accuracy of the classification as a function of pastiness was 88.5%; meanwhile, according to colour was 79.7%. Partial least squares regression was used to formulate prediction equations for pastiness and colour. The correlation coefficients of calibration and cross-validation were 0.97 and 0.86 for optimal equation predicting pastiness, and 0.82 and 0.69 for optimal equation predicting colour. The standard error of cross-validation for predicting pastiness and colour is between 1 and 2 times the standard deviation of the reference method (the error involved in the sensory evaluation by the experts). The magnitude of this error demonstrates the good precision of the methods for predicting pastiness and colour. Furthermore, the samples were classified into defective or no defective classes, with a correct classification of 94.2% according to pasty texture evaluation and 75.7% as regard to colour evaluation.

An exploratory study of linguistic-colour associations across languages in multilingual synaesthetes.

PubMed

Barnett, Kylie J; Feeney, Joanne; Gormley, Michael; Newell, Fiona N

2009-07-01

In one of the most common forms of synaesthesia, linguistic-colour synaesthesia, colour is induced by stimuli such as numbers, letters, days of the week, and months of the year. It is not clear, however, whether linguistic-colour synaesthesia is determined more by higher level semantic information--that is, word meaning--or by lower level grapheme or phoneme structure. To explore this issue, we tested whether colour is consistently induced by grapheme or phoneme form or word meaning in bilingual and trilingual linguistic-colour synaesthetes. We reasoned that if the induced colour was related to word meaning, rather than to the acoustic or visual properties of the words, then the induced colours would remain consistent across languages. We found that colours were not consistently related to word meaning across languages. Instead, induced colours were more related to form properties of the word across languages, particularly visual structure. However, the type of inducing stimulus influenced specific colour associations. For example, colours to months of the year were more consistent across languages than were colours to numbers or days of the week. Furthermore, the effect of inducing stimuli was also associated with the age of acquisition of additional languages. Our findings are discussed with reference to a critical period in language acquisition on synaesthesia.

The galaxy UV luminosity function at z ≃ 2-4; new results on faint-end slope and the evolution of luminosity density

NASA Astrophysics Data System (ADS)

Parsa, Shaghayegh; Dunlop, James S.; McLure, Ross J.; Mortlock, Alice

2016-03-01

We present a new, robust measurement of the evolving rest-frame ultraviolet (UV) galaxy luminosity function (LF) over the key redshift range from z ≃ 2 to z ≃ 4. Our results are based on the high dynamic range provided by combining the Hubble Ultra Deep Field (HUDF), CANDELS/GOODS-South, and UltraVISTA/COSMOS surveys. We utilize the unparalleled multifrequency photometry available in this survey `wedding cake' to compile complete galaxy samples at z ≃ 2, 3, 4 via photometric redshifts (calibrated against the latest spectroscopy) rather than colour-colour selection, and to determine accurate rest-frame UV absolute magnitudes (M1500) from spectral energy distribution (SED) fitting. Our new determinations of the UV LF extend from M1500 ≃ -22 (AB mag) down to M1500 = -14.5, -15.5 and -16 at z ≃ 2, 3 and 4, respectively (thus, reaching ≃ 3-4 mag fainter than previous blank-field studies at z ≃ 2,3). At z ≃ 2, 3, we find a much shallower faint-end slope (α = -1.32 ± 0.03) than reported in some previous studies (α ≃ -1.7), and demonstrate that this new measurement is robust. By z ≃ 4, the faint-end slope has steepened slightly, to α = -1.43 ± 0.04, and we show that these measurements are consistent with the overall evolutionary trend from z = 0 to 8. Finally, we find that while characteristic number density (φ*) drops from z ≃ 2 to z ≃ 4, characteristic luminosity (M*) brightens by ≃ 1 mag. This, combined with the new flatter faint-end slopes, has the consequence that UV luminosity density (and hence unobscured star formation density) peaks at z ≃ 2.5-3, when the Universe was ≃ 2.5 Gyr old.

How temporal cues can aid colour constancy

PubMed Central

Foster, David H.; Amano, Kinjiro; Nascimento, Sérgio M. C.

2007-01-01

Colour constancy assessed by asymmetric simultaneous colour matching usually reveals limited levels of performance in the unadapted eye. Yet observers can readily discriminate illuminant changes on a scene from changes in the spectral reflectances of the surfaces making up the scene. This ability is probably based on judgements of relational colour constancy, in turn based on the physical stability of spatial ratios of cone excitations under illuminant changes. Evidence is presented suggesting that the ability to detect violations in relational colour constancy depends on temporal transient cues. Because colour constancy and relational colour constancy are closely connected, it should be possible to improve estimates of colour constancy by introducing similar transient cues into the matching task. To test this hypothesis, an experiment was performed in which observers made surface-colour matches between patterns presented in the same position in an alternating sequence with period 2 s or, as a control, presented simultaneously, side-by-side. The degree of constancy was significantly higher for sequential presentation, reaching 87% for matches averaged over 20 observers. Temporal cues may offer a useful source of information for making colour-constancy judgements. PMID:17515948

First CCD UBVI photometric analysis of six open cluster candidates

NASA Astrophysics Data System (ADS)

Piatti, A. E.; Clariá, J. J.; Ahumada, A. V.

2011-04-01

We have obtained CCD UBVIKC photometry down to V ˜ 22 for the open cluster candidates Haffner 3, Haffner 5, NGC 2368, Haffner 25, Hogg 3 and Hogg 4 and their surrounding fields. None of these objects have been photometrically studied so far. Our analysis shows that these stellar groups are not genuine open clusters since no clear main sequences or other meaningful features can be seen in their colour-magnitude and colour-colour diagrams. We checked for possible differential reddening across the studied fields that could be hiding the characteristics of real open clusters. However, the dust in the directions to these objects appears to be uniformly distributed. Moreover, star counts carried out within and outside the open cluster candidate fields do not support the hypothesis that these objects are real open clusters or even open cluster remnants.

Influence of drug colour on perceived drug effects and efficacy.

PubMed

Tao, Da; Wang, Tieyan; Wang, Tieshan; Qu, Xingda

2018-02-01

A drug's physical characteristics, such as colour, could be factors influencing its therapeutic effects. It is not well understood whether people's expectations on drug effects and efficacy are affected by colour, especially among Chinese population. This study was conducted to examine people's expectations on drug effects and efficacy on the basis of drug colour, and to reveal possible gender differences in colour-related drug expectations. Participants (n = 224) were asked to classify seven single-coloured and six two-coloured capsules into one of four categories of drug effects, and to indicate the strength of drug efficacy. It is found that all the coloured capsules yielded non-chance distributions in classifications of drug effects, with six single-coloured and four two-coloured capsules associated with specific drug effects. Colour also conveyed differential strengths of drug efficacy in general and in relation to specific drug effects. There were gender differences in drug expectations for some colours and colour combinations. Practitioner Summary: Drug colour was found to have impacts on perceived drug effects and efficacy. The findings from the present study can be used by ergonomics practitioners to design appropriate drug colours in support of drug differentiation, therapeutic effects and medication adherence.

Hopkins Ultraviolet Telescope determination of the Io torus electron temperature

NASA Technical Reports Server (NTRS)

Hall, D. T.; Bednar, C. J.; Durrance, S. T.; Feldman, P. D.; Mcgrath, M. A.; Moos, H. W.; Strobel, D. F.

1994-01-01

Sulfur ion emissions from the Io plasma torus observed by the Hopkins Ultraviolet Telescope (HUT) in 1990 December have been analyzed to determine the effective temperature of the exciting electrons. Spectra were obtained with a long slit that extended from 3.1 to 8.7 Jupiter radii R(sub J) on both dawn and dusk torus ansae. The average temperature of electrons exciting S(2+) emissions from the dawn ansa is (4800 +/- 2400) K lower than on the dusk ansa, a dawn-dusk asymmetry comparable in both sign and magnitude to that measured by the Voyager Ultraviolet Spectrograph (UVS) experiment. Emissions from S(2+) ions are generated in a source region with electron temperatures in the range 32,000-56,000 K; S(3+) ion emissions are excited by electrons that average 20,000-40,000 K hotter. This distinct difference suggests that the S(3+) emission source region is spatially separate from the S(2+) source region. Estimated relative aperture filling factors suggest that the S(3+) emissions originate from a region more extended out of the centrifugal plane than the S(2+) emissions.

An asymptotic safety scenario for gauged chiral Higgs-Yukawa models

NASA Astrophysics Data System (ADS)

Gies, Holger; Rechenberger, Stefan; Scherer, Michael M.; Zambelli, Luca

2013-12-01

We investigate chiral Higgs-Yukawa models with a non-abelian gauged left-handed sector reminiscent to a sub-sector of the standard model. We discover a new weak-coupling fixed-point behavior that allows for ultraviolet complete RG trajectories which can be connected with a conventional long-range infrared behavior in the Higgs phase. This non-trivial ultraviolet behavior is characterized by asymptotic freedom in all interaction couplings, but a quasi conformal behavior in all mass-like parameters. The stable microscopic scalar potential asymptotically approaches flatness in the ultraviolet, however, with a non-vanishing minimum increasing inversely proportional to the asymptotically free gauge coupling. This gives rise to non-perturbative—though weak-coupling—threshold effects which induce ultraviolet stability along a line of fixed points. Despite the weak-coupling properties, the system exhibits non-Gaußian features which are distinctly different from its standard perturbative counterpart: e.g., on a branch of the line of fixed points, we find linear instead of quadratically running renormalization constants. Whereas the Fermi constant and the top mass are naturally of the same order of magnitude, our model generically allows for light Higgs boson masses. Realistic mass ratios are related to particular RG trajectories with a "walking" mid-momentum regime.

The search for multiple populations in Magellanic Cloud clusters - IV. Coeval multiple stellar populations in the young star cluster NGC 1978

NASA Astrophysics Data System (ADS)

Martocchia, S.; Niederhofer, F.; Dalessandro, E.; Bastian, N.; Kacharov, N.; Usher, C.; Cabrera-Ziri, I.; Lardo, C.; Cassisi, S.; Geisler, D.; Hilker, M.; Hollyhead, K.; Kozhurina-Platais, V.; Larsen, S.; Mackey, D.; Mucciarelli, A.; Platais, I.; Salaris, M.

2018-07-01

We have recently shown that the ˜2 Gyr old Large Magellanic Cloud star cluster NGC 1978 hosts multiple populations in terms of star-to-star abundance variations in [N/Fe]. These can be seen as a splitting or spread in the subgiant and red giant branches (SGB and RGB) when certain photometric filter combinations are used. Because of its relative youth, NGC 1978 can be used to place stringent limits on whether multiple bursts of star formation have taken place within the cluster, as predicted by some models for the origin of multiple populations. We carry out two distinct analyses to test whether multiple star formation epochs have occurred within NGC 1978. First, we use ultraviolet colour-magnitude diagrams (CMDs) to select stars from the first and second population along the SGB, and then compare their positions in optical CMDs, where the morphology is dominantly controlled by age as opposed to multiple population effects. We find that the two populations are indistinguishable, with age differences of 1 ± 20 Myr between them. This is in tension with predictions from the asymptotic giant branch scenario for the origin of multiple populations. Second, we estimate the broadness of the main-sequence turn-off (MSTO) of NGC 1978 and we report that it is consistent with the observational errors. We find an upper limit of ˜65 Myr on the age spread in the MSTO of NGC 1978. This finding is in conflict with the age spread scenario as origin of the extended MSTO in intermediate-age clusters, while it fully supports predictions from the stellar rotation model.

New Metallicty Calibration for Dwarfs for the RGU-Photometry

NASA Astrophysics Data System (ADS)

Karaali, Salih; Bilir, Selçuk

2002-10-01

We adopted the procedure of Carney to obtain a metallicity calibration for dwarfs for the RGU photometry. For this purpose we selected 76 dwarfs of different metallicities from Carney, and Strobel et al., and evaluated their δ(U-G) ultra-violet excess relative to Hyades by transforming their UBV magnitudes to RGU via metallicity dependent equations of Ak-Güngör. The δ0.6/ΔM normalized factors of Sandage transform Δ(U-G) excess at any G-R to δ=δ1.08, i.e.: the ultra-violet excess at G-R = 1.08 mag, corresponding to B-V = 0.60 mag in the UBV-system. Finally, the (δ, [Fe/H]) couples were fitted by the equation [Fe/H] = 0.11-2.22δ-7.95δ2. This calibration covers the metallicity interval (-2.20, +0.20) dex.

Sexual maturation and control issues among sexually abused and non-abused anorexia patients.

PubMed

Walsh, J; Burns, F

2000-09-01

To assess the relative salience of the maintenance of control and the avoidance of sexual maturation as sources of motivation for maintaining pathological eating behaviours among sexually abused anorexic patients. A two-factor mixed experimental design was employed. Three independent groups (sexually abused anorexics (N = 12); non-abused anorexics (N = 9); non-anorexic/non-abused controls (N = 12)) constituted the between-subjects factor. Allocation to abuse/non-abuse group was dependent upon replies to a questionnaire-based measure of unwanted sexual experience. The within-subjects factor comprised three conditions in which words of various colours were presented to participants for colour-naming (Stroop, 1935). The conditions were represented by lists of neutral words, sexual maturation words, and control-related words. Two trials were carried out in each condition and mean response times were measured. Within-group analyses revealed that interference was greater from sexual maturation words than from control-related words among the sexually-abused anorexics, but of equal magnitude among non-abused counterparts. Between-groups analyses found that abused patients experienced marginally greater cognitive interference from sexual maturation words than the non-abused patients. Theoretically, support is offered for elaborated schematic models of cognitive processing. Clinically, treatment interventions may need to pay particular attention to issues of sexual maturation among sexually abused anorexic patients.

The Galaxy Color-Magnitude Diagram in the Local Universe from GALEX and SDSS Data

NASA Astrophysics Data System (ADS)

Wyder, T. K.; GALEX Science Team

2005-12-01

We present the relative density of galaxies in the local universe as a function of their r-band absolute magnitudes and ultraviolet minus r-band colors. The Sloan Digital Sky Survey (SDSS) main galaxy sample selected in the r-band was matched with a sample of galaxies from the Galaxy Evolution Explorer (GALEX) Medium Imaging Survey in both the far-UV (FUV) and near-UV (NUV) bands. Simlar to previous optical studies, the distribution of galaxies in (FUV-r) and (NUV-r) is bimodal with well-defined blue and red sequences. We compare the distribution of galaxies in these colors with both the D4000 index measured from the SDSS spectra as well as the SDSS (u-r) color.

Molecular logic behind the three-way stochastic choices that expand butterfly colour vision.

PubMed

Perry, Michael; Kinoshita, Michiyo; Saldi, Giuseppe; Huo, Lucy; Arikawa, Kentaro; Desplan, Claude

2016-07-14

Butterflies rely extensively on colour vision to adapt to the natural world. Most species express a broad range of colour-sensitive Rhodopsin proteins in three types of ommatidia (unit eyes), which are distributed stochastically across the retina. The retinas of Drosophila melanogaster use just two main types, in which fate is controlled by the binary stochastic decision to express the transcription factor Spineless in R7 photoreceptors. We investigated how butterflies instead generate three stochastically distributed ommatidial types, resulting in a more diverse retinal mosaic that provides the basis for additional colour comparisons and an expanded range of colour vision. We show that the Japanese yellow swallowtail (Papilio xuthus, Papilionidae) and the painted lady (Vanessa cardui, Nymphalidae) butterflies have a second R7-like photoreceptor in each ommatidium. Independent stochastic expression of Spineless in each R7-like cell results in expression of a blue-sensitive (Spineless(ON)) or an ultraviolet (UV)-sensitive (Spineless(OFF)) Rhodopsin. In P. xuthus these choices of blue/blue, blue/UV or UV/UV sensitivity in the two R7 cells are coordinated with expression of additional Rhodopsin proteins in the remaining photoreceptors, and together define the three types of ommatidia. Knocking out spineless using CRISPR/Cas9 (refs 5, 6) leads to the loss of the blue-sensitive fate in R7-like cells and transforms retinas into homogeneous fields of UV/UV-type ommatidia, with corresponding changes in other coordinated features of ommatidial type. Hence, the three possible outcomes of Spineless expression define the three ommatidial types in butterflies. This developmental strategy allowed the deployment of an additional red-sensitive Rhodopsin in P. xuthus, allowing for the evolution of expanded colour vision with a greater variety of receptors. This surprisingly simple mechanism that makes use of two binary stochastic decisions coupled with local coordination may prove to be a general means of generating an increased diversity of developmental outcomes.

VizieR Online Data Catalog: Period-mass-loss rate relation of Miras (Uttenthaler, 2013)

NASA Astrophysics Data System (ADS)

Uttenthaler, S.

2013-06-01

Table 1 is a collection of information on the technetium (Tc) content, pulsation period, and IR photometry of AGB variables, without claim of completeness, in particular for the semi-regular variables (SRVs). Up to three references on the Tc content are given. The pulsation period is the most up-to-date value possible, for many objects based on an analysis of AAVSO data with the Period04 program (Lenz & Breger, 2005CoAst.146...53L). The spectral (or chemical) type of the star is taken from the same literature as the information on Tc. A mean K magnitude and J-K colour is computed from all available literature, as listed in Sect. 2 of the paper; they are meant to be as close as possible to cycle-averaged values, to average out the variability of the objects. Finally, magnitudes are given in the IRAS 12, 25, and 60 micron bands, Akari 9 and 18 micron bands, and WISE 22 micron bands are given, where fluxes have been converted to magnitudes given the zero-magnitude fluxes as given in the Note to Table 1. (1 data file).

First ultraviolet observations of the transition regions of X-ray bright solar-type stars in the Pleiades

NASA Technical Reports Server (NTRS)

Caillault, J.-P.; Vilhu, O.; Linsky, J. L.

1990-01-01

Results are reported from A UV study of the transition regions of two X-ray-bright solar-type stars from the Pleiades, in an attempt to extend the main sequence age baseline for the transition-region activity-age relation over more than two orders of magnitude. However, no emission lines were detected from either star; the upper limits to the fluxes are consistent with previously determined saturation levels, but do not help to further constrain evolutionary models.

Visual ecology of the Australian lungfish (Neoceratodus forsteri)

PubMed Central

Hart, Nathan S; Bailes, Helena J; Vorobyev, Misha; Marshall, N Justin; Collin, Shaun P

2008-01-01

Background The transition from water to land was a key event in the evolution of vertebrates that occurred over a period of 15–20 million years towards the end of the Devonian. Tetrapods, including all land-living vertebrates, are thought to have evolved from lobe-finned (sarcopterygian) fish that developed adaptations for an amphibious existence. However, while many of the biomechanical and physiological modifications necessary to achieve this feat have been studied in detail, little is known about the sensory adaptations accompanying this transition. In this study, we investigated the visual system and visual ecology of the Australian lungfish Neoceratodus forsteri, which is the most primitive of all the lungfish and possibly the closest living relative to the ancestors of tetrapods. Results Juvenile Neoceratodus have five spectrally distinct retinal visual pigments. A single type of rod photoreceptor contains a visual pigment with a wavelength of maximum absorbance (λmax) at 540 nm. Four spectrally distinct single cone photoreceptors contain visual pigments with λmax at 366 (UVS), 479 (SWS), 558 (MWS) and 623 nm (LWS). No double cones were found. Adult lungfish do not possess UVS cones and, unlike juveniles, have ocular media that prevent ultraviolet light from reaching the retina. Yellow ellipsoidal/paraboloidal pigments in the MWS cones and red oil droplets in the LWS cones narrow the spectral sensitivity functions of these photoreceptors and shift their peak sensitivity to 584 nm and 656 nm, respectively. Modelling of the effects of these intracellular spectral filters on the photoreceptor colour space of Neoceratodus suggests that they enhance their ability to discriminate objects, such as plants and other lungfishes, on the basis of colour. Conclusion The presence of a complex colour vision system based on multiple cone types and intracellular spectral filters in lungfishes suggests that many of the ocular characteristics seen in terrestrial or secondarily aquatic vertebrates, such as birds and turtles, may have evolved in shallow water prior to the transition onto land. Moreover, the benefits of spectral filters for colour discrimination apply equally to purely aquatic species as well as semi-aquatic and terrestrial animals. The visual system of the Australian lungfish resembles that of terrestrial vertebrates far more closely than that of other sarcopterygian fish. This supports the idea that lungfishes, and not the coelacanth, are the closest living relatives of the ancestors of tetrapods. PMID:19091135

Spectral shifts of mammalian ultraviolet-sensitive pigments (short wavelength-sensitive opsin 1) are associated with eye length and photic niche evolution.

PubMed

Emerling, Christopher A; Huynh, Hieu T; Nguyen, Minh A; Meredith, Robert W; Springer, Mark S

2015-11-22

Retinal opsin photopigments initiate mammalian vision when stimulated by light. Most mammals possess a short wavelength-sensitive opsin 1 (SWS1) pigment that is primarily sensitive to either ultraviolet or violet light, leading to variation in colour perception across species. Despite knowledge of both ultraviolet- and violet-sensitive SWS1 classes in mammals for 25 years, the adaptive significance of this variation has not been subjected to hypothesis testing, resulting in minimal understanding of the basis for mammalian SWS1 spectral tuning evolution. Here, we gathered data on SWS1 for 403 mammal species, including novel SWS1 sequences for 97 species. Ancestral sequence reconstructions suggest that the most recent common ancestor of Theria possessed an ultraviolet SWS1 pigment, and that violet-sensitive pigments evolved at least 12 times in mammalian history. We also observed that ultraviolet pigments, previously considered to be a rarity, are common in mammals. We then used phylogenetic comparative methods to test the hypotheses that the evolution of violet-sensitive SWS1 is associated with increased light exposure, extended longevity and longer eye length. We discovered that diurnal mammals and species with longer eyes are more likely to have violet-sensitive pigments and less likely to possess UV-sensitive pigments. We hypothesize that (i) as mammals evolved larger body sizes, they evolved longer eyes, which limited transmittance of ultraviolet light to the retina due to an increase in Rayleigh scattering, and (ii) as mammals began to invade diurnal temporal niches, they evolved lenses with low UV transmittance to reduce chromatic aberration and/or photo-oxidative damage. © 2015 The Author(s).

Spectral shifts of mammalian ultraviolet-sensitive pigments (short wavelength-sensitive opsin 1) are associated with eye length and photic niche evolution

PubMed Central

Emerling, Christopher A.; Huynh, Hieu T.; Nguyen, Minh A.; Meredith, Robert W.; Springer, Mark S.

2015-01-01

Retinal opsin photopigments initiate mammalian vision when stimulated by light. Most mammals possess a short wavelength-sensitive opsin 1 (SWS1) pigment that is primarily sensitive to either ultraviolet or violet light, leading to variation in colour perception across species. Despite knowledge of both ultraviolet- and violet-sensitive SWS1 classes in mammals for 25 years, the adaptive significance of this variation has not been subjected to hypothesis testing, resulting in minimal understanding of the basis for mammalian SWS1 spectral tuning evolution. Here, we gathered data on SWS1 for 403 mammal species, including novel SWS1 sequences for 97 species. Ancestral sequence reconstructions suggest that the most recent common ancestor of Theria possessed an ultraviolet SWS1 pigment, and that violet-sensitive pigments evolved at least 12 times in mammalian history. We also observed that ultraviolet pigments, previously considered to be a rarity, are common in mammals. We then used phylogenetic comparative methods to test the hypotheses that the evolution of violet-sensitive SWS1 is associated with increased light exposure, extended longevity and longer eye length. We discovered that diurnal mammals and species with longer eyes are more likely to have violet-sensitive pigments and less likely to possess UV-sensitive pigments. We hypothesize that (i) as mammals evolved larger body sizes, they evolved longer eyes, which limited transmittance of ultraviolet light to the retina due to an increase in Rayleigh scattering, and (ii) as mammals began to invade diurnal temporal niches, they evolved lenses with low UV transmittance to reduce chromatic aberration and/or photo-oxidative damage. PMID:26582021

Planetary nebulae search in the outskirts of M33: looking for the farthest candidates

NASA Astrophysics Data System (ADS)

Galera Rosillo, Rebeca; Corradi, Romano L. M.; Mampaso Recio, Antonio

2015-08-01

The nearby disc galaxy M33 is one of the best laboratories for testing chemical evolution models in galaxies and for understanding disc formation mechanisms. In this galaxy, planetary nebulae (PNe) were previously extensively studied only within a galactocentric radius of 8 kpc.In the framework of a broad study of the population of PNe in Local Group disc galaxies, we present the results of a deep narrow-band imaging of the outer regions of M33, performed using the Wide Field Camera at the 2.5 m Isaac Newton Telescope (INT).The INT images were obtained in the narrow-band filters selecting the [OIII] 5007 Å and Hα 6563 Å lines, plus broad-band filters SDSS g and i. A photometric catalog of around 150000 sources covering a total area of 5 square degrees, and extending out to 2 deg (30 kpc at the adopted distance of 840 kpc) from the centre of the galaxy is presented.PNe candidates are selected in the [OIII]-g vs Hα-r colour-colour diagram as bright emitters in the narrowband filters. A number of candidates with similar colours to those of known PNe, and with an apparent [OIII] magnitude > 21 have been selected for future follow-up. Three of these have been already spectroscopically confirmed at the William Herschel Telescope (WHT).Our survey will improve the knowledge of the PNe population in the outskirts of M33, constraining the properties of its metal-poor halo and of the extended disc substructures that have been proposed to be related to a relatively recent interaction with M31.

Solar ultraviolet radiation in Africa: a systematic review and critical evaluation of the health risks and use of photoprotection.

PubMed

Lucas, Robyn M; Norval, Mary; Wright, Caradee Y

2016-01-01

Most information on the harmful health effects of solar ultraviolet radiation (UVR) has been obtained in populations in which the majority has fair skin. Here a systematic review of evidence on diseases related to solar UVR in Africa was undertaken, and the appropriateness of effective photoprotection for these people considered. There are few population-based studies on UV-induced skin cancers (melanoma, squamous and basal cell carcinomas) in Africa, although limited reports indicated that they occur, even in people with deeply pigmented skin. The incidence of melanoma is particularly high in the white population living in the Western Cape of South Africa and has increased significantly in recent years. Cataract is extremely common in people of all skin colours and is a frequent cause of blindness, particularly in the elderly. For both skin cancer and cataract, the proportion of the disease risk that is attributable to exposure to solar UVR in African populations, and therefore the health burden caused by UV irradiation is unclear. There was little published information on the use of sun protection in Africa. The potential disease burden attributable to solar UVR exposure of Africans is high, although accurate data to quantify this are sparse. Information is required on the incidence, prevalence and mortality for the range of UV-related diseases in different populations living throughout Africa. Photoprotection is clearly required, at least for those subpopulations at particularly high risk, but may be limited by cost and cultural acceptability.

A study of the H I and optical properties of Low Surface Brightness galaxies: spirals, dwarfs, and irregulars

NASA Astrophysics Data System (ADS)

Honey, M.; van Driel, W.; Das, M.; Martin, J.-M.

2018-06-01

We present a study of the H I and optical properties of nearby (z ≤ 0.1) Low Surface Brightness galaxies (LSBGs). We started with a literature sample of ˜900 LSBGs and divided them into three morphological classes: spirals, irregulars, and dwarfs. Of these, we could use ˜490 LSBGs to study their H I and stellar masses, colours, and colour-magnitude diagrams, and local environment, compare them with normal, High Surface Brightness (HSB) galaxies and determine the differences between the three morphological classes. We found that LSB and HSB galaxies span a similar range in H I and stellar masses, and have a similar M_{H I}/M⋆-M⋆ relationship. Among the LSBGs, as expected, the spirals have the highest average H I and stellar masses, both of about 109.8 M⊙. The LSGBs' (g - r) integrated colour is nearly constant as function of H I mass for all classes. In the colour-magnitude diagram, the spirals are spread over the red and blue regions whereas the irregulars and dwarfs are confined to the blue region. The spirals also exhibit a steeper slope in the M_{H I}/M⋆-M⋆ plane. Within their local environment, we confirmed that LSBGs are more isolated than HSB galaxies, and LSB spirals more isolated than irregulars and dwarfs. Kolmogorov-Smirnov statistical tests on the H I mass, stellar mass, and number of neighbours indicate that the spirals are a statistically different population from the dwarfs and irregulars. This suggests that the spirals may have different formation and H I evolution than the dwarfs and irregulars.

A comprehensive photometric study of dynamically evolved small van den Bergh-Hagen open clusters

NASA Astrophysics Data System (ADS)

Piatti, Andrés E.

2016-12-01

We present results from Johnson UBV, Kron-Cousins RI and Washington CT1T2 photometries for seven van den Bergh-Hagen (vdBH) open clusters, namely, vdBH 1, 10, 31, 72, 87, 92, and 118. The high-quality, multiband photometric data sets were used to trace the cluster stellar density radial profiles and to build colour-magnitude diagrams and colour-colour diagrams from which we estimated their structural parameters and fundamental astrophysical properties. The clusters in our sample cover a wide age range, from ˜60 Myr up to 2.8 Gyr, are of relatively small size (˜1-6 pc) and are placed at distances from the Sun which vary between 1.8 and 6.3 kpc, respectively. We also estimated lower limits for the cluster present-day masses as well as half-mass relaxation times (tr). The resulting values in combination with the structural parameter values suggest that the studied clusters are in advanced stages of their internal dynamical evolution (age/tr ˜ 20-320), possibly in the typical phase of those tidally filled with mass segregation in their core regions. Compared to open clusters in the solar neighbourhood, the seven vdBH clusters are within more massive (˜80-380 M⊙), with higher concentration parameter values (c ˜ 0.75-1.15) and dynamically evolved ones.

The Las Campanas Infrared Survey - II. Photometric redshifts, comparison with models and clustering evolution

NASA Astrophysics Data System (ADS)

Firth, A. E.; Somerville, R. S.; McMahon, R. G.; Lahav, O.; Ellis, R. S.; Sabbey, C. N.; McCarthy, P. J.; Chen, H.-W.; Marzke, R. O.; Wilson, J.; Abraham, R. G.; Beckett, M. G.; Carlberg, R. G.; Lewis, J. R.; Mackay, C. D.; Murphy, D. C.; Oemler, A. E.; Persson, S. E.

2002-05-01

The Las Campanas Infrared (LCIR) Survey, using the Cambridge Infra-Red Survey Instrument (CIRSI), reaches H ~21 over nearly 1deg2 . In this paper we present results from 744arcmin2 centred on the Hubble Deep Field South for which UBVRI optical data are publicly available. Making conservative magnitude cuts to ensure spatial uniformity, we detect 3177 galaxies to H =20.0 in 744arcmin2 and a further 842 to H =20.5 in a deeper subregion of 407arcmin2 . We compare the observed optical-infrared (IR) colour distributions with the predictions of semi-analytic hierarchical models and find reasonable agreement. We also determine photometric redshifts, finding a median redshift of ~0.55. We compare the redshift distributions N (z ) of E, Sbc, Scd and Im spectral types with models, showing that the observations are inconsistent with simple passive-evolution models while semi-analytic models provide a reasonable fit to the total N (z ) but underestimate the number of z ~1 red spectral types relative to bluer spectral types. We also present N (z ) for samples of extremely red objects (EROs) defined by optical-IR colours. We find that EROs with R -H >4 and H <20.5 have a median redshift z m ~1 while redder colour cuts have slightly higher z m . In the magnitude range 194 comprise ~18 per cent of the observed galaxy population, while in semi-analytic models they contribute only ~4 per cent. We also determine the angular correlation function w (θ ) for magnitude, colour, spectral type and photometric redshift-selected subsamples of the data and use the photometric redshift distributions to derive the spatial clustering statistic ξ (r ) as a function of spectral type and redshift out to z ~1.2. Parametrizing ξ (r ) by ξ (r c ,z )=[r c /r *(z )]-1.8 , where r c is in comoving coordinates, we find that r *(z ) increases by a factor of 1.5-2 from z =0 to z ~1.2. We interpret this as a selection effect - the galaxies selected at z ~1.2 are intrinsically very luminous, about 1-1.5mag brighter than L *. When galaxies are selected by absolute magnitude, we find no evidence for evolution in r * over this redshift range. Extrapolated to z =0, we find r *(z =0)~6.5h -1 Mpc for red galaxies and r *(z =0)~2-4h -1 Mpc for blue galaxies. We also find that, while the angular clustering amplitude of EROs with R -H >4 or I -H >3 is up to four times that of the whole galaxy population, the spatial clustering length r *(z =1) is ~7.5-10.5h -1 Mpc, which is only a factor of ~1.7 times r *(z =1) for R -H <4 and I -H <3 galaxies lying in a similar redshift and luminosity range. This difference is similar to that observed between red and blue galaxies at low redshifts.

Colour application on mammography image segmentation

NASA Astrophysics Data System (ADS)

Embong, R.; Aziz, N. M. Nik Ab.; Karim, A. H. Abd; Ibrahim, M. R.

2017-09-01

The segmentation process is one of the most important steps in image processing and computer vision since it is vital in the initial stage of image analysis. Segmentation of medical images involves complex structures and it requires precise segmentation result which is necessary for clinical diagnosis such as the detection of tumour, oedema, and necrotic tissues. Since mammography images are grayscale, researchers are looking at the effect of colour in the segmentation process of medical images. Colour is known to play a significant role in the perception of object boundaries in non-medical colour images. Processing colour images require handling more data, hence providing a richer description of objects in the scene. Colour images contain ten percent (10%) additional edge information as compared to their grayscale counterparts. Nevertheless, edge detection in colour image is more challenging than grayscale image as colour space is considered as a vector space. In this study, we implemented red, green, yellow, and blue colour maps to grayscale mammography images with the purpose of testing the effect of colours on the segmentation of abnormality regions in the mammography images. We applied the segmentation process using the Fuzzy C-means algorithm and evaluated the percentage of average relative error of area for each colour type. The results showed that all segmentation with the colour map can be done successfully even for blurred and noisy images. Also the size of the area of the abnormality region is reduced when compare to the segmentation area without the colour map. The green colour map segmentation produced the smallest percentage of average relative error (10.009%) while yellow colour map segmentation gave the largest percentage of relative error (11.367%).

Carotenoid-based bill colour is an integrative signal of multiple parasite infection in blackbird

NASA Astrophysics Data System (ADS)

Biard, Clotilde; Saulnier, Nicolas; Gaillard, Maria; Moreau, Jérôme

2010-11-01

In the study of parasite-mediated sexual selection, there has been controversial evidence for the prediction that brighter males should have fewer parasites. Most of these studies have focused on one parasite species. Our aim was to investigate the expression of carotenoid-based coloured signals in relation to patterns of multiple parasite infections, to determine whether colour reflects parasite load of all parasite species, or whether different relationships might be found when looking at each parasite species independently. We investigated the relationship between bill colour, body mass and plasma carotenoids and parasite load (feather chewing lice, blood parasite Plasmodium sp., intestinal parasites cestodes and coccidia) in the blackbird ( Turdus merula). Bill colour on its own appeared to be a poor predictor of parasite load when investigating its relationships with individual parasite species. Variation in parasite intensities at the community level was summarised using principal component analysis to derive synthetic indexes of relative parasite species abundance and absolute parasite load. The relative abundance of parasite species was strongly related to bill colour, plasma carotenoid levels and body mass: birds with relatively more cestodes and chewing lice and relatively less Plasmodium and coccidia had a more colourful bill, circulated more carotenoids and were heavier. These results suggest that bill colour more accurately reflects the relative intensities of parasite infection, rather than one-by-one relationships with parasites or absolute parasite burden. Investigating patterns of multiple parasite infection would thus improve our understanding of the information conveyed by coloured signals on parasite load.

The colour preference control based on two-colour combinations

NASA Astrophysics Data System (ADS)

Hong, Ji Young; Kwak, Youngshin; Park, Du-Sik; Kim, Chang Yeong

2008-02-01

This paper proposes a framework of colour preference control to satisfy the consumer's colour related emotion. A colour harmony algorithm based on two-colour combinations is developed for displaying the images with several complementary colour pairs as the relationship of two-colour combination. The colours of pixels belonging to complementary colour areas in HSV colour space are shifted toward the target hue colours and there is no colour change for the other pixels. According to the developed technique, dynamic emotions by the proposed hue conversion can be improved and the controlled output image shows improved colour emotions in the preference of the human viewer. The psychophysical experiments are conducted to investigate the optimal model parameters to produce the most pleasant image to the users in the respect of colour emotions.

The First Billion Years project: constraining the dust attenuation law of star-forming galaxies at z ≃ 5

NASA Astrophysics Data System (ADS)

Cullen, F.; McLure, R. J.; Khochfar, S.; Dunlop, J. S.; Dalla Vecchia, C.

2017-09-01

We present the results of a study investigating the dust attenuation law at z ≃ 5, based on synthetic spectral energy distributions (SEDs) calculated for a sample of N = 498 galaxies drawn from the First Billion Years (FiBY) simulation project. The simulated galaxies at z ≃ 5, which have M1500 ≤ -18.0 and 7.5 ≤ log(M/M}_{⊙}) ≤ 10.2, display a mass-dependent α-enhancement, with a median value of [α /{Fe}]_{z=5} ˜eq 4 × [α /{Fe}]_{Z_{⊙}}. The median Fe/H ratio of the simulated galaxies is 0.14 ± 0.05 which produces steep intrinsic ultraviolet (UV) continuum slopes; 〈βI〉 = -2.4 ± 0.05. Using a set of simple dust attenuation models, in which the wavelength-dependent attenuation is assumed to be of the form A(λ) ∝ λn, we explore the parameter values which best reproduce the observed z = 5 luminosity function (LF) and colour-magnitude relation (CMR). We find that a simple model in which the absolute UV attenuation is a linearly increasing function of log stellar mass (A1500 = 0.5 × log(M/M⊙) - 3.3), and the dust attenuation slope (n) is within the range -0.7 ≤ n ≤ -0.3, can successfully reproduce the LF and CMR over a wide range of stellar population synthesis model assumptions, including the effects of massive binaries. This range of attenuation curves is consistent with a power-law fit to the Calzetti attenuation law in the UV (n = -0.55). In contrast, curves as steep as the Small Magellanic Cloud extinction curve (n = -1.24) are formally ruled out. Finally, we show that our models are consistent with recent 1.3 mm Atacama Large Millimeter Array observations of the Hubble Ultra Deep Field, and predict the form of the z ≃ 5 infrared excess (IRX)-β relation.

Seven-color Vilnius photometry and classification of stars in the region of the North Ecliptic Pole

NASA Astrophysics Data System (ADS)

Zdanavičius, K.; Straižys, V.; Zdanavičius, J.; Chmieliauskaitė, R.; Kazlauskas, A.

2012-08-01

The results of photometry of 948 stars down to V = 16.2 mag in the Vilnius seven-color system at the North Ecliptic Pole (NEP) are presented. Among them, 293 stars have all seven magnitudes, 331 stars have no ultraviolet magnitudes and 324 stars have no ultraviolet and violet magnitudes. Photometric data are used to classify about 500 stars in spectral and luminosity classes. For the remaining stars one-dimensional spectral classes are given. Some stars are suspected as new F and G subdwarfs and metal-deficient giants. The dependence of interstellar extinction on distance in the direction of NEP is discussed. The average extinction in the area for stars with d > 500 pc is found to be AV = 0.10 ± 0.01 mag, with the standard deviation 0.14 mag. The results of photometry and classification can be used to supplement the catalog of Gaia standard stars near the Ecliptic poles. To facilitate this, we present transformation of the Vilnius magnitudes to the magnitudes of the SDSS and Gaia systems. Full Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/544/A49.

Far-Ultraviolet Number Counts of Field Galaxies

NASA Technical Reports Server (NTRS)

Voyer, Elysse N.; Gardner, Jonathan P.; Teplitz, Harry I.; Siana, Brian D.; deMello, Duilia F.

2010-01-01

The Number counts of far-ultraviolet (FUV) galaxies as a function of magnitude provide a direct statistical measure of the density and evolution of star-forming galaxies. We report on the results of measurements of the rest-frame FUV number counts computed from data of several fields including the Hubble Ultra Deep Field, the Hubble Deep Field North, and the GOODS-North and -South fields. These data were obtained from the Hubble Space Telescope Solar Blind Channel of the Advance Camera for Surveys. The number counts cover an AB magnitude range from 20-29 magnitudes, covering a total area of 15.9 arcmin'. We show that the number counts are lower than those in previous studies using smaller areas. The differences in the counts are likely the result of cosmic variance; our new data cover more area and more lines of sight than the previous studies. The slope of our number counts connects well with local FUV counts and they show good agreement with recent semi-analytical models based on dark matter "merger trees".

Testing the relativistic Doppler boost hypothesis for supermassive black hole binary candidates

NASA Astrophysics Data System (ADS)

Charisi, Maria; Haiman, Zoltán; Schiminovich, David; D'Orazio, Daniel J.

2018-06-01

Supermassive black hole binaries (SMBHBs) should be common in galactic nuclei as a result of frequent galaxy mergers. Recently, a large sample of sub-parsec SMBHB candidates was identified as bright periodically variable quasars in optical surveys. If the observed periodicity corresponds to the redshifted binary orbital period, the inferred orbital velocities are relativistic (v/c ≈ 0.1). The optical and ultraviolet (UV) luminosities are expected to arise from gas bound to the individual BHs, and would be modulated by the relativistic Doppler effect. The optical and UV light curves should vary in tandem with relative amplitudes which depend on the respective spectral slopes. We constructed a control sample of 42 quasars with aperiodic variability, to test whether this Doppler colour signature can be distinguished from intrinsic chromatic variability. We found that the Doppler signature can arise by chance in ˜20 per cent (˜37 per cent) of quasars in the nUV (fUV) band. These probabilities reflect the limited quality of the control sample and represent upper limits on how frequently quasars mimic the Doppler brightness+colour variations. We performed separate tests on the periodic quasar candidates, and found that for the majority, the Doppler boost hypothesis requires an unusually steep UV spectrum or an unexpectedly large BH mass and orbital velocity. We conclude that at most approximately one-third of these periodic candidates can harbor Doppler-modulated SMBHBs.

Polarization properties and microfacet-based modelling of white, grey and coloured matte diffuse reflection standards

NASA Astrophysics Data System (ADS)

Quast, T.; Schirmacher, A.; Hauer, K.-O.; Koo, A.

2018-02-01

To elucidate the influence of polarization in diffuse reflectometry, we performed a series of measurements in several bidirectional geometries and determined the Stokes parameters of the diffusely reflected radiation. Different types of matte reflection standards were used, including several common white standards and ceramic colour standards. The dependence of the polarization on the sample type, wavelength and geometry have been studied systematically, the main influence factors have been identified: The effect is largest at large angles of incidence or detection and at wavelengths where the magnitude of the reflectance is small. The results for the colour standards have been modelled using a microfacet-based reflection theory which is derived from the well-known model of Torrance and Sparrow. Although the theory is very simple and only has three free parameters, the agreement with the measured data is very good, all essential features of the data can be reproduced by the model.

Caracterizacion y optimizacion electroquimica de dispositivos electrocromicos duales basados en polimeros conductores

NASA Astrophysics Data System (ADS)

Padilla Martinez, Javier

The aim of this thesis is to emphasize the existing relations between electrochemical processes, or electrochemical magnitudes, and colour changes. The work is focused on two aspects: individual spectroelectrochemical characterization of the constituent materials followed by an electrochemical and optical study of the performance of the dual system constructed with those materials. The objective is the optimization of both electrochemical and optical processes in dual conducting polymer systems, obtaining experimental methodologies able to characterize, predict, and finally design optimal dual electrochromic devices. The first part of the study is focused on the development of the proper methodology to obtain an optical characterization of any electrochromic material as a function of its electrochemical properties. Materials used were poly((3,4-ethylenedioxy)thiophene) (PEDOT) and poly-(3,6-bis(2-(3,4-ethylenedioxy)thienyl)-N-methylcarbazole) (PBEDOT-NMCz). PEDOT films are coloured under reduction, while PBEDOT-NMCz are coloured under oxidation, showing complementary colouration, and so they can be used to construct a dual electrochromic device. Based on the obtained experimental results, a theoretical study was undertaken to establish the optical responses of a system comprising several electrochromic layers. The theoretically obtained relations were experimentally proved. Relations obtained allow the prediction of the maximum contrast configuration for a dual system, as a function of the individual electrochemical properties of each constituent material. The system studied was PEDOT/PBEDOT-NMCz. The third chapter deals with the proposal and development of a new experimental methodology able to register the individual oxidation states of each electrode during operation of a dual device, obtaining then direct information about device performance. This methodology allows the study of the influence of different physical and chemical variables, like ratio of redox charge between both constituent films, applied potential to the device and initial oxidation state of the constituent polymer films, on the device performance. The final objective of this work is the construction of electrochromic devices that can be use in real applications out of research or academic contexts. It is necessary then, for safety purposes, to use solid electrolytes in the cell. For final applications it is also required to construct devices of appropriate dimensions. In the fourth chapter, the construction and study of large dimensions and solid state devices for the system PEDOT/PBEDOT-NMCz was carried out. The information obtained in previous sections was used to determine maximum contrast combinations. Problems related to electrodeposition of conducting polymers on large surfaces (around 30 cm2) are discussed, together with the optimization of switching speeds when a solid electrolyte is used. Finally the ability to tune colour states and retain them in the absence of an external potential applied was studied and discussed. The last section deals with the study of two new cathodically colouring polymers, poly(3-(Biphenyl-4-ylmethoxymethyl)-3,4-dihydro-2H-thieno(3,4-b)-(1,2)dioxepine) (BPMOM-ProDOT) and poly-dibenzylProDOT (PDiBz-ProDOT), which have been reported to show larger contrasts than PEDOT. For this reason, dual cells were constructed and checked by combination of these two polymers with PBEDOT-NMCz. The methodology previously developed and used to characterize PEDOT and PBEDOT-NMCz was applied to these polymers. The developed theoretical equations were used to determine the maximum contrast for both systems. Finally, the use of standard optical magnitudes as photopic values is emphasized. Photopic values are standardized by the Commission Internationale de l'Eclairage (CIE), and correspond to real sensations perceived by the human eye, whose sensitivity is different for each wavelength. In this sense the use of photopic values, instead of values corresponding to a single wavelength, is encouraged. (Abstract shortened by UMI.)

A deep view on the Virgo cluster core

NASA Astrophysics Data System (ADS)

Lieder, S.; Lisker, T.; Hilker, M.; Misgeld, I.; Durrell, P.

2012-02-01

Studies of dwarf spheroidal (dSph) galaxies with statistically significant sample sizes are still rare beyond the Local Group, since these low surface brightness objects can only be identified with deep imaging data. In galaxy clusters, where they constitute the dominant population in terms of number, they represent the faint end slope of the galaxy luminosity function and provide important insight on the interplay between galaxy mass and environment. In this study we investigate the optical photometric properties of early-type galaxies (dwarf ellipticals (dEs) and dSphs) in the Virgo cluster core region, by analysing their location on the colour magnitude relation (CMR) and the structural scaling relations down to faint magnitudes, and by constructing the luminosity function to compare it with theoretical expectations. Our work is based on deep CFHT V- and I-band data covering several square degrees of the Virgo cluster core that were obtained in 1999 using the CFH12K instrument. We visually select potential cluster members based on morphology and angular size, excluding spiral galaxies. A photometric analysis has been carried out for 295 galaxies, using surface brightness profile shape and colour as further criteria to identify probable background contaminants. 216 galaxies are considered to be certain or probable Virgo cluster members. Our study reveals 77 galaxies not catalogued in the VCC (with 13 of them already found in previous studies) that are very likely Virgo cluster members because they follow the Virgo CMR and exhibit low Sérsic indices. Those galaxies reach MV = -8.7 mag. The CMR shows a clear change in slope from dEs to dSphs, while the scatter of the CMR in the dSph regime does not increase significantly. Our sample might, however, be somewhat biased towards redder colours. The scaling relations given by the dEs appear to be continued by the dSphs indicating a similar origin. The observed change in the CMR slope may mark the point at which gas loss prevented significant metal enrichment. The almost constant scatter around the CMR possibly indicates a short formation period, resulting in similar stellar populations. The luminosity function shows a Schechter function's faint end slope of α = -1.50 ± 0.17, implying a lack of galaxies related to the expected number of low-mass dark matter haloes from theoretical models. Our findings could be explained by suppressed star formation in low-mass dark matter halos or by tidal disruption of dwarfs in the dense core region of the cluster. Tables 3 and 4 are available in electronic form at http://www.aanda.org

The role of colour in signalling and male choice in the agamid lizard Ctenophorus ornatus.

PubMed Central

LeBas, N R; Marshall, N J

2000-01-01

Bright coloration and complex visual displays are frequent and well described in many lizard families. Reflectance spectrometry which extends into the ultraviolet (UV) allows measurement of such coloration independent of our visual system. We examined the role of colour in signalling and mate choice in the agamid lizard Ctenophorus ornatus. We found that throat reflectance strongly contrasted against the granite background of the lizards' habitat. The throat may act as a signal via the head-bobbing and push-up displays of C. ornatus. Dorsal coloration provided camouflage against the granite background, particularly in females. C. ornatus was sexually dichromatic for all traits examined including throat UV reflectance which is beyond human visual perception. Female throats were highly variable in spectral reflectance and males preferred females with higher throat chroma between 370 and 400 nm. However, female throat UV chroma is strongly correlated to both throat brightness and chest UV chroma and males may choose females on a combination of these colour variables. There was no evidence that female throat or chest coloration was an indicator of female quality. However, female brightness significantly predicted a female's laying date and, thus, may signal receptivity. One function of visual display in this species appears to be intersexual signalling, resulting in male choice of females. PMID:10737400

Studies on Coloration and UV Protective Action of Anar Peel (Pomegranate Rind) as an Effective Natural Colorant for Cotton Khadi Fabric

NASA Astrophysics Data System (ADS)

Sinnur, H. D.; Samanta, Ashis Kumar; Verma, D. K.; Kaware, Runali

2018-06-01

Besides optimization of conditions of colour extraction from dried anar peel, effect of different single and double mordants, dyeing process variables and UV protective action of anar peels (pomegranate rind i.e. Punica granatum L.) as a natural colourant is studied in this work. Mordants used are potash alum, aluminium sulphate and stannous chloride (as metallic salt mordant) and harda (i.e., myrobolan as natural mordant) from natural source. Relevant results indicate that 50:50 ratio of harda plus potash aluminium sulphate at overall 15% application level offers maximum K/S value and overall good colour fastness than any other combination. After finalizing the mordants, dyeing process variables were studied for standardization of conditions for dyeing cotton khadi fabric with aqueous extract of pomegranate rind. The results indicate that standardized conditions for dyeing are (a) dyeing time : 60 min, (b) dyeing temperature: 80 °C, (c) dye bath MLR : 1:30, (d) dye bath pH : 9.0, (e) max dye concentration : 20% and (f) common salt : 3%. Studies of FTIR, UV scan, Atomic Absorption Spectrophotometry (AAS) and UV Protection Factor (UPF) characters show a medium to good level of ultraviolet protection. Corresponding reaction mechanism amongst mordant/fibre and dye forming giant complex is also reported.

Studies on Coloration and UV Protective Action of Anar Peel (Pomegranate Rind) as an Effective Natural Colorant for Cotton Khadi Fabric

NASA Astrophysics Data System (ADS)

Sinnur, H. D.; Samanta, Ashis Kumar; Verma, D. K.; Kaware, Runali

2017-10-01

Besides optimization of conditions of colour extraction from dried anar peel, effect of different single and double mordants, dyeing process variables and UV protective action of anar peels (pomegranate rind i.e. Punica granatum L.) as a natural colourant is studied in this work. Mordants used are potash alum, aluminium sulphate and stannous chloride (as metallic salt mordant) and harda (i.e., myrobolan as natural mordant) from natural source. Relevant results indicate that 50:50 ratio of harda plus potash aluminium sulphate at overall 15% application level offers maximum K/S value and overall good colour fastness than any other combination. After finalizing the mordants, dyeing process variables were studied for standardization of conditions for dyeing cotton khadi fabric with aqueous extract of pomegranate rind. The results indicate that standardized conditions for dyeing are (a) dyeing time : 60 min, (b) dyeing temperature: 80 °C, (c) dye bath MLR : 1:30, (d) dye bath pH : 9.0, (e) max dye concentration : 20% and (f) common salt : 3%. Studies of FTIR, UV scan, Atomic Absorption Spectrophotometry (AAS) and UV Protection Factor (UPF) characters show a medium to good level of ultraviolet protection. Corresponding reaction mechanism amongst mordant/fibre and dye forming giant complex is also reported.

VizieR Online Data Catalog: GRB 120327A afterglow colour variations (Melandri+, 2017)

NASA Astrophysics Data System (ADS)

Melandri, A.; Covino, S.; Zaninoni, E.; Campana, S.; Bolmer, J.; Cobb, B. E.; Gorosabel, J.; Kim, J.-W.; Kuin, P.; Kuroda, D.; Malesani, D.; Mundell, C. G.; Nappo, F.; Sbarufatti, B.; Smith, R. J.; Steele, I. A.; Topinka, M.; Trotter, A. S.; Virgili, F. J.; Bernardini, M. G.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Ghirlanda, G.; Gomboc, A.; Greiner, J.; Guidorzi, C.; Haislip, J. B.; Hanayama, H.; Hanlon, L.; Im, M.; Ivarsen, K. M.; Japelj, J.; Jelinek, M.; Kawai, N.; Kobayashi, S.; Kopac, D.; Lacluyze, A. P.; Martin-Carrillo, A.; Murphy, D.; Reichart, D. E.; Salvaterra, R.; Salafia, O. S.; Tagliaferri, G.; Vergani, S. D.

2017-09-01

Photometric data of GRB120327A are presented. Magnitudes are in the Vega system unless for griz filters that are in the AB system, and they are all not corrected for Galactic absorption. Errors are at 1sigma level. (1 data file).

Inverse opal with an ultraviolet photonic gap

NASA Astrophysics Data System (ADS)

Ni, Peigen; Cheng, Bingying; Zhang, Daozhong

2002-03-01

Photonic crystals composed of TiO2 and air voids fabricated by the template method exhibit an ultraviolet photonic stop band (˜380 nm) in the Γ-L direction. Scanning electron microscopy images show that the inverse opal possesses face-centered-cubic symmetry with a lattice constant of 240 nm. The transmission spectra show that the change in transmittance is one order of magnitude in the gap, which is in accord with the reflection spectrum.

Relationship between natural tooth shade and skin colour.

PubMed

Nourbakhsh, M; Mousavinejad, N; Adli, A R; Harati, M

2013-06-01

The purpose of this study was to assess the correlation of skin colour and tooth shade. One hundred and twenty six individuals aging between 18 to 25 years participated in this study. Colour of the maxillary central incisors was examined by VITA easy shade. Tooth shades were assigned to four ordinal values. Nivea Beauty Protect Foundation shade sample was used as a guide to assess facial skin colour Shin colours were also assigned to four ordinal values. Spearman test revealed that there was a significant relationship between tooth shade and skin colour Total co-relation factor was 51.6% (p <0 .01). Co-relation factors were 57% for women and 27% for men (p <0 .01). The highest tooth shade prevalence belonged to the second group and the highest skin colour prevalence was also in the second skin colour group.

Rethinking Colour Constancy.

PubMed

Logvinenko, Alexander D; Funt, Brian; Mirzaei, Hamidreza; Tokunaga, Rumi

2015-01-01

Colour constancy needs to be reconsidered in light of the limits imposed by metamer mismatching. Metamer mismatching refers to the fact that two objects reflecting metameric light under one illumination may reflect non-metameric light under a second; so two objects appearing as having the same colour under one illuminant can appear as having different colours under a second. Yet since Helmholtz, object colour has generally been believed to remain relatively constant. The deviations from colour constancy registered in experiments are usually thought to be small enough that they do not contradict the notion of colour constancy. However, it is important to determine how the deviations from colour constancy relate to the limits metamer mismatching imposes on constancy. Hence, we calculated metamer mismatching's effect for the 20 Munsell papers and 8 pairs of illuminants employed in the colour constancy study by Logvinenko and Tokunaga and found it to be so extensive that the two notions-metamer mismatching and colour constancy-must be mutually exclusive. In particular, the notion of colour constancy leads to some paradoxical phenomena such as the possibility of 20 objects having the same colour under chromatic light dispersing into a hue circle of colours under neutral light. Thus, colour constancy refers to a phenomenon, which because of metamer mismatching, simply cannot exist. Moreover, it obscures the really important visual phenomenon; namely, the alteration of object colours induced by illumination change. We show that colour is not an independent, intrinsic attribute of an object, but rather an attribute of an object/light pair, and then define a concept of material colour in terms of equivalence classes of such object/light pairs. We suggest that studying the shift in material colour under a change in illuminant will be more fruitful than pursuing colour constancy's false premise that colour is an intrinsic attribute of an object.

Colour preferences and colour vision in poultry chicks.

PubMed

Ham, A D; Osorio, D

2007-08-22

The dramatic colours of biological communication signals raise questions about how animals perceive suprathreshold colour differences, and there are long-standing questions about colour preferences and colour categorization by non-human species. This study investigates preferences of foraging poultry chicks (Gallus gallus) as they peck at coloured objects. Work on colour recognition often deals with responses to monochromatic lights and how animals divide the spectrum. We used complementary colours, where the intermediate is grey, and related the chicks' choices to three models of the factors that may affect the attractiveness. Two models assume that attractiveness is determined by a metric based on the colour discrimination threshold either (i) by chromatic contrast against the background or (ii) relative to an internal standard. An alternative third model is that categorization is important. We tested newly hatched and 9-day-old chicks with four pairs of (avian) complementary colours, which were orange, blue, red and green for humans. Chromatic contrast was more relevant to newly hatched chicks than to 9-day-old birds, but in neither case could contrast alone account for preferences; especially for orange over blue. For older chicks, there is evidence for categorization of complementary colours, with a boundary at grey.

VizieR Online Data Catalog: VI photometry of Berkeley 66 (Guarnieri+ 1997)

NASA Astrophysics Data System (ADS)

Guarnieri, M. D.; Carraro, G.

1996-06-01

A colour magnitude diagram (CMD) extending to V=~19mag is given for 444 stars in the region of the galactic cluster Berkeley 66. The V and I photometry of a nearby field is also reported. This object appears very faint, highly contaminated by foreground stars and very reddened. The apparent distance modulus (m-M) and the colour excess EV-I are guessed to be 17.5 and 1.1, respectively, with an uncertainty of at least 30%. Adopting these values the comparison of the CMD with theoretical isochrones from the Padova group provides an age around 1.0Gyr. (1 data file).

Behavioural evidence of colour vision in free flying stingless bees.

PubMed

Spaethe, J; Streinzer, M; Eckert, J; May, S; Dyer, A G

2014-06-01

Colour vision was first demonstrated with behavioural experiments in honeybees 100 years ago. Since that time a wealth of quality physiological data has shown a highly conserved set of trichromatic colour receptors in most bee species. Despite the subsequent wealth of behavioural research on honeybees and bumblebees, there currently is a relative dearth of data on stingless bees, which are the largest tribe of the eusocial bees comprising of more than 600 species. In our first experiment we tested Trigona cf. fuscipennis, a stingless bee species from Costa Rica in a field setting using the von Frisch method and show functional colour vision. In a second experiment with these bees, we use a simultaneous colour discrimination test designed for honeybees to enable a comparative analysis of relative colour discrimination. In a third experiment, we test in laboratory conditions Tetragonula carbonaria, an Australian stingless bee species using a similar simultaneous colour discrimination test. Both stingless bee species show relatively poorer colour discrimination compared to honeybees and bumblebees; and we discuss the value of being able to use these behavioural methods to efficiently extend our current knowledge of colour vision and discrimination in different bee species.

Binding of motion and colour is early and automatic.

PubMed

Blaser, Erik; Papathomas, Thomas; Vidnyánszky, Zoltán

2005-04-01

At what stages of the human visual hierarchy different features are bound together, and whether this binding requires attention, is still highly debated. We used a colour-contingent motion after-effect (CCMAE) to study the binding of colour and motion signals. The logic of our approach was as follows: if CCMAEs can be evoked by targeted adaptation of early motion processing stages, without allowing for feedback from higher motion integration stages, then this would support our hypothesis that colour and motion are bound automatically on the basis of spatiotemporally local information. Our results show for the first time that CCMAE's can be evoked by adaptation to a locally paired opposite-motion dot display, a stimulus that, importantly, is known to trigger direction-specific responses in the primary visual cortex yet results in strong inhibition of the directional responses in area MT of macaques as well as in area MT+ in humans and, indeed, is perceived only as motionless flicker. The magnitude of the CCMAE in the locally paired condition was not significantly different from control conditions where the different directions were spatiotemporally separated (i.e. not locally paired) and therefore perceived as two moving fields. These findings provide evidence that adaptation at an early, local motion stage, and only adaptation at this stage, underlies this CCMAE, which in turn implies that spatiotemporally coincident colour and motion signals are bound automatically, most probably as early as cortical area V1, even when the association between colour and motion is perceptually inaccessible.

Colour-stability and gloss-retention of silorane and dimethacrylate composites with accelerated aging.

PubMed

Furuse, Adilson Y; Gordon, Kathryn; Rodrigues, Flávia P; Silikas, Nick; Watts, David C

2008-11-01

To evaluate the colour-stability and gloss-retention of silorane versus dimethacrylate composites exposed to accelerated aging from daylight radiation. Five disc-shaped specimens of photo-cured resin-composites were prepared and manually polished for each material (Filtek Silorane, Herculite XRV, Tetric Evoceram and QuiXfil). Colour and gloss were evaluated before and after periods (baseline, 24, 72, 120 and 192 h) of accelerated photo-aging in xenon light following ISO 7491:2000. Colour measurements were performed with a colourimeter according to the CIE-Lab colour-space. The colour change (DeltaE) for each time was calculated. The surface gloss was measured using a glossmeter. Results were evaluated using one-way ANOVA and Tukey tests (alpha=0.05). Correlations between logtime, DeltaE and gloss were evaluated using Pearson's correlation (alpha=0.05). Materials generally decreased in L and a and increased in b. The strong exception was Filtek Silorane which maintained a and b. DeltaE was found to be a positive linear function of logtime for all materials. Materials varied in the magnitude and rate of increase of DeltaE with logtime: QuiXfil>Tetric EvoCeram>(Filtek Silorane>or=Herculite XRV). DeltaE remained<3.3 for Filtek Silorane and Herculite XRV. Gloss was found to be a negative linear function of logtime. Gloss was maximal in the sequence: Filtek Silorane approximately Tetric EvoCeram>Herculite XRV>QuiXfil. Silorane gave the best overall performance in stability over time, compared to a set of representative dimethacrylate composites.

Working memory in children and adolescents with Down syndrome: evidence from a colour memory experiment.

PubMed

Laws, Glynis

2002-03-01

This paper reports information on the visual and verbal short-term memory of individuals with Down syndrome. Colour memory in 16 children and adolescents with Down syndrome was compared with that of 16 typically developing children matched for receptive vocabulary. It was suggested that focal colours should be remembered more successfully than non-focal colours on the basis that the former could be remembered using a verbal recoding strategy. However, children with Down syndrome, for whom a deficit in verbal short-term memory makes the use of such a strategy unlikely, should remember focal and non-focal colours equally well. More importantly, if individuals with Down syndrome have more developed visual memory abilities than control children, they should outperform them in recognising non-focal colours. Although the group with Down syndrome demonstrated significantly better Corsi blocks performance than controls, and displayed similar levels of colour knowledge, no advantage for colour memory was found. Non-focal colours were remembered by individuals with Down syndrome as successfully as focal colours but there was no indication of a visual memory advantage over controls. Focal colours were remembered significantly more successfully than non-focal colours by the typically developing children. Their focal colour memory was significantly related to digit span, but only Corsi span was related to focal colour memory in the group with Down syndrome.

Semantically induced distortions of visual awareness in a patient with Balint's syndrome.

PubMed

Soto, David; Humphreys, Glyn W

2009-02-01

We present data indicating that visual awareness for a basic perceptual feature (colour) can be influenced by the relation between the feature and the semantic properties of the stimulus. We examined semantic interference from the meaning of a colour word (''RED") on simple colour (ink related) detection responses in a patient with simultagnosia due to bilateral parietal lesions. We found that colour detection was influenced by the congruency between the meaning of the word and the relevant ink colour, with impaired performance when the word and the colour mismatched (on incongruent trials). This result held even when remote associations between meaning and colour were used (i.e. the word ''PEA" influenced detection of the ink colour red). The results are consistent with a late locus of conscious visual experience that is derived at post-semantic levels. The implications for the understanding of the role of parietal cortex in object binding and visual awareness are discussed.

Modelling energy efficiency of an integrated anaerobic digestion and photodegradation of distillery effluent using response surface methodology.

PubMed

Apollo, Seth; Onyango, Maurice S; Ochieng, Aoyi

2016-10-01

Anaerobic digestion (AD) is efficient in organic load removal and bioenergy recovery when applied in treating distillery effluent; however, it is ineffective in colour reduction. In contrast, ultraviolet (UV) photodegradation post-treatment for the AD-treated distillery effluent is effective in colour reduction but has high energy requirement. The effects of operating parameters on bioenergy production and energy demand of photodegradation were modelled using response surface methodology (RSM) with a view of developing a sustainable process in which the biological step could supply energy to the energy-intensive photodegradation step. The organic loading rate (OLRAD) and hydraulic retention time (HRTAD) of the initial biological step were the variables investigated. It was found that the initial biological step removed about 90% of COD and only about 50% colour while photodegradation post-treatment removed 98% of the remaining colour. Maximum bioenergy production of 180.5 kWh/m(3) was achieved. Energy demand of the UV lamp was lowest at low OLRAD irrespective of HRTAD, with values ranging between 87 and 496 kWh/m(3). The bioenergy produced formed 93% of the UV lamp energy demand when the system was operated at OLRAD of 3 kg COD/m(3) d and HRT of 20 days. The presumed carbon dioxide emission reduction when electricity from bioenergy was used to power the UV lamp was 28.8 kg CO2 e/m(3), which could reduce carbon emission by 31% compared to when electricity from the grid was used, leading to environmental conservation.

VizieR Online Data Catalog: NGC 2264, NGC 2547 and NGC 2516 stellar radii (Jackson+, 2016)

NASA Astrophysics Data System (ADS)

Jackson, R. J.; Jeffries, R. D.; Randich, S.; Bragaglia, A.; Carraro, G.; Costado, M. T.; Flaccomio, E.; Lanzafame; Lardo, C.; Monaco, L.; Morbidelli, L.; Smiljanic, R.; Zaggia, S.

2015-11-01

File Table1.dat contains Photometric and spectroscopic data of GES Survey targets in clusters in NGC 2547, NGC 2516, NGC 22264 downloaded from the Edinburugh GES archive (http://ges/roe.ac.uk/) . Photometric data comprised the (Cousins) I magnitude and 2MASS J, H and K magnitudes. Spectroscopic data comprises the signal to noise ratio, S/N of the target spectrum, the radial velocity, RV (in km/s), the projected equatorial velocity, vsini (in km/s), the number of separate observations co-added to produce the target spectrum and the log of effective temperature (logTeff) of the template spectrum fitted to measure RV and vsini. The absolute precision in RV, pRV (in km/s) and relative precision vsini (pvsini) were estimated, as a function of the logTeff, vsini and S/N, using the prescription described in Jackson et al. (2015A&A...580A..75J, Cat. J/A+A/580/A75). File Table3.dat contains measured and calculated properties of cluster targets with resolved vsini and a reported rotation period. The cluster name, right ascension, RA (deg) and declination, Dec (deg) are given for targets with measured periods given in the literature. Dynamic properties comprise: the radial velocity, RV (in km/s), the absolute precision in RV, pRV (km/s), the projected equatorial velocity, vsini (in km/s), the relative precision in vsini (pvsini) and the rotational period (in days). Also shown are values of absolute K magnitude, MK log of luminosity, log L (in solar units) and probability of cluster membership estimated using cluster data given in the text. Period shows reported values of cluster taken from the literature Estimated values of the projected radius, Rsini (in Rsolar) and uncertainty in projected radius, e_Rsini (in Rsolar) are given for targets where vsini>5km/s and pvsini>0.2. The final column shows a flag which is set to 1 for targets in cluster NGC 2264 where a (H-K) versus (J-H) colour-colour plot indicates possible infra-red excess. Period shows reported values of cluster taken from the literature (2 data files).

Does task-irrelevant colour information create extraneous cognitive load? Evidence from a learning task.

PubMed

Miller, Paul; Hazan-Liran, Batel; Cohen, Danielle

2018-06-01

Previous studies have shown that task-irrelevant information impedes learning by creating extraneous cognitive load. But still open is whether such intrusion reflects a purely semantic phenomenon or whether it also stands for sheer perceptual interference. Using Cognitive Load Theory as a framework, this study aimed to answer this question by examining whether and how task-irrelevant colour information modifies extraneous cognitive load in relation to a new code-learning paradigm. For this purpose, university students were asked to learn, based on an example, associations between colour-related and colour-unrelated words and digits presented in black or in a mismatched ink colour. Evident costs in learning efficacy were found in learning the associations between words and digits for colour-related, but not for colour-unrelated, word stimuli. This suggests that interference by task-irrelevant information in learning stands for a mere semantic conflict. Implications of the findings for extraneous cognitive load on learning efficacy are discussed.

Spectroscopic survey of the far-ultraviolet /1160-1700 A/ emissions of Capella

NASA Technical Reports Server (NTRS)

Vitz, R. C.; Weiser, H.; Moos, H. W.; Weinstein, A.; Warden, E. S.

1976-01-01

A far-ultraviolet spectral survey of Capella (Alpha Aur, G5 III + G0 III) has been obtained using a highly sensitive rocketborne spectrograph with a microchannel plate detector. The spectral distribution is very similar to that of the sun; however, if the line surface fluxes are due to the primary (G5 III), then, except for Ly-alpha, they are about an order of magnitude greater than those of the quiet sun

Broadband ultraviolet reflectance filters for space applications.

NASA Technical Reports Server (NTRS)

Osantowski, J. F.; Toft, A. R.

1973-01-01

It is shown that a simple metal-dielectric-metal filter for broadband ultraviolet (BUV) reflectance control can provide a stable and effective means for reducing stray visible radiation in UV reflective optical systems. The application of such a filter in a BUV instrument resulted in a reduction of scattered visible light by at least an order of magnitude. The instrument has been in orbit for 2.5 year without loss of sensitivity or an increase in scattered light background.-

The Swift/UVOT catalogue of NGC 4321 star-forming sources: a case against density wave theory

NASA Astrophysics Data System (ADS)

Ferreras, Ignacio; Cropper, Mark; Kawata, Daisuke; Page, Mat; Hoversten, Erik A.

2012-08-01

We study the star-forming regions in the spiral galaxy NGC 4321 (M100). We take advantage of the spatial resolution (2.5 arcsec full width at half-maximum) of the Swift/Ultraviolet/Optical Telescope camera and the availability of three ultraviolet (UV) passbands in the region 1600 < λ < 3000 Å, in combination with optical and infrared (IR) imaging from Sloan Digital Sky Survey, KPNO/Hα and Spitzer/IRAC, to obtain a catalogue of 787 star-forming regions out to three disc scalelengths. We use a large volume of star formation histories, combined with stellar population synthesis, to determine the properties of the young stellar component and its relationship with the spiral arms. The Hα luminosities of the sources have a strong decreasing radial trend, suggesting more massive star-forming regions in the central part of the galaxy. When segregated with respect to near-UV (NUV)-optical colour, blue sources have a significant excess of flux in the IR at 8 μm, revealing the contribution from polycyclic aromatic hydrocarbons, although the overall reddening of these sources stays below E(B - V) = 0.2 mag. The distribution of distances to the spiral arms is compared for subsamples selected according to Hα luminosity, NUV-optical colour or ages derived from a population synthesis model. An offset would be expected between these subsamples as a function of radius if the pattern speed of the spiral arm were constant - as predicted by classic density wave theory. No significant offsets are found, favouring instead a mechanism where the pattern speed has a radial dependence.

The early ultraviolet, optical, and radio evolution of the soft X-ray transient GRO J0422+32

NASA Technical Reports Server (NTRS)

Shrader, C. R.; Wagner, R. Mark; Hjellming, R. M.; Han, X. H.; Starrfield, S. G.

1994-01-01

We have monitored the evolution of the transient X-ray source GRO J0422+32 from approximately 2 weeks postdiscovery into its early decline phase at ultraviolet, optical, and radio wavelengths. Optical and ultraviolet spectra exhibit numerous, but relatively weak, high-excitation emission lines such as those arising from He II, N III, N V, and C IV superposed on an intrinsically blue continuum. High-resolution optical spectroscopy reveals line profiles which are double peaked, and in the case of the higher order Balmer lines, superposed on a broad absorption profile. The early outburst optical-ultraviolet continuum energy distribution is well represented by a two power-law fit with a break at approximately equal 4000 A. Radio observations with the Very Large Array (VLA) reveal a flat-spectrum source, slowly increasing in intensity at the earliest epochs observed, followed by an approximate power-law decay light curve with an index of -1. Light curves for each wavelength domain are presented and discussed. Notable are the multiple secondary outbursts seen in the optical more than 1 year postdiscovery, and spectral changes associated with secondary rises seen in the radio and UV. We find that the ultraviolet and optical characteristics of GRO J0422+32 as well as its radio evolution, are similar to other recent well-observed soft X-ray transients (also called X-ray novae) such as Cen X-4, A0620-00 (V616 Mon), and Nova Muscae 1991 (GS 1124-683), suggesting that GRO J0422+32 is also a member of that subclass of low-mass X-ray binaries. We present definitive astrometric determination of the source position, and place an upper limit of R approximately equals 20 from our analysis of the Palomar Observatory Sky Survey (POSS). Additionally, we derive distinct values for color excess from analysis of the optical (E(B-V) = 0.23) and ultraviolet (E(B-V) = 0.4) data, suggesting an intrinsic magnitude of 19-19.5 for the progenitor if it is mid-K dwarf. This leads to a likely range of 2.4-3.0 kpc for the source distance, which is consistent with our separate estimate of 2.4 +/- 0.4 kpc based on measurement of the NaD interstellar line profile. Adopting 2.4 kpc and E(B-V) = 0.23, the outburst absolute magnitude was M approximately equals 0.0, which is a typical value for this class of objects.

Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

PubMed Central

Wang, He; Xu, Yiming; Ulonska, Stefan; Robinson, Joseph S.; Ranitovic, Predrag; Kaindl, Robert A.

2015-01-01

Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. Here, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 1013 s−1 is generated at 22.3 eV, with 5 × 10−5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications. PMID:26067922

Feedback-related potentials in a gambling task with randomised reward.

PubMed

Mushtaq, Faisal; Guillen, Pablo Puente; Wilkie, Richard M; Mon-Williams, Mark A; Schaefer, Alexandre

2016-03-01

Event-related potentials (ERPs) time-locked to decision outcomes are reported. Participants engaged in a gambling task (see [1] for details) in which they decided between a risky and a safe option (presented as different coloured shapes) on each trial (416 in total). Each decision was associated with (fully randomised) feedback about the reward outcome (Win/Loss) and its magnitude (varying as a function of decision response; 5-9 points for Risky decisions and 1-4 points for Safe decisions). Here, we show data demonstrating: (a) the influence of Win feedback in the preceding outcome (Outcome t-1) on activity related to the current outcome (Outcome t ); (b) difference wave analysis for outcome expectancy- separating Expected Outcomes (consecutive Loss trials subtracted from consecutive reward) from Unexpected Outcomes (subtracting Loss t-1Win t trials from Win t-1Loss t trials); (c) difference waves separating Switch and Stay responses for Outcome Expectancy; (d) the effect of magnitude induced by decisions (Risk t vs. Safe t ) on Outcome Expectancy; and finally, (e) expectations reflected by response switch direction (Risk to Safe responses vs. Safe to Risk t ) on the FRN at Outcome t .

Rethinking Colour Constancy

PubMed Central

Logvinenko, Alexander D.; Funt, Brian; Mirzaei, Hamidreza; Tokunaga, Rumi

2015-01-01

Colour constancy needs to be reconsidered in light of the limits imposed by metamer mismatching. Metamer mismatching refers to the fact that two objects reflecting metameric light under one illumination may reflect non-metameric light under a second; so two objects appearing as having the same colour under one illuminant can appear as having different colours under a second. Yet since Helmholtz, object colour has generally been believed to remain relatively constant. The deviations from colour constancy registered in experiments are usually thought to be small enough that they do not contradict the notion of colour constancy. However, it is important to determine how the deviations from colour constancy relate to the limits metamer mismatching imposes on constancy. Hence, we calculated metamer mismatching’s effect for the 20 Munsell papers and 8 pairs of illuminants employed in the colour constancy study by Logvinenko and Tokunaga and found it to be so extensive that the two notions—metamer mismatching and colour constancy—must be mutually exclusive. In particular, the notion of colour constancy leads to some paradoxical phenomena such as the possibility of 20 objects having the same colour under chromatic light dispersing into a hue circle of colours under neutral light. Thus, colour constancy refers to a phenomenon, which because of metamer mismatching, simply cannot exist. Moreover, it obscures the really important visual phenomenon; namely, the alteration of object colours induced by illumination change. We show that colour is not an independent, intrinsic attribute of an object, but rather an attribute of an object/light pair, and then define a concept of material colour in terms of equivalence classes of such object/light pairs. We suggest that studying the shift in material colour under a change in illuminant will be more fruitful than pursuing colour constancy’s false premise that colour is an intrinsic attribute of an object. PMID:26356217

What do we really know about the signalling role of plumage colour in blue tits? A case study of impediments to progress in evolutionary biology.

PubMed

Parker, Timothy H

2013-08-01

Evolutionary biologists seek to explain the origin and maintenance of phenotypes, and a substantial portion of this research is accomplished by thorough study of individual species. For instance, many researchers study individual species to understand evolution of ornamental traits which appear to be products of sexual selection. I explored our understanding of sexual ornaments in a well-studied vertebrate species that may serve as a case study for research programs in evolutionary biology. I attempted to located all published papers examining plumage colour and variables related to sexual selection hypotheses in a common European songbird, the blue tit (Cyanistes caeruleus). Researchers have estimated over 1200 statistical relationships with plumage colour of blue tits in 52 studies. However, of the approximately 1000 main-effect relationships from the 48 studies that are candidates for inclusion in this meta-analysis, more than 400 were reported without details of strength and direction. Circumstantial evidence suggests that an unknown number of other estimated effects remain unpublished. Missing information is a substantial barrier to interpretation of these papers and to meta-analytic synthesis. Examination and analysis of funnel plots indicated that unpublished effects may be a biased sample of all effects, especially for comparisons of plumage colour to age and individual quality, and possibly also to measures of mate choice. Further, type I error was likely elevated by the large number of statistical comparisons evaluated, the frequent use of iterative model-building procedures, and a willingness to interpret a wide variety of results as support for a hypothesis. Type I errors were made more problematic because blue tit plumage researchers only rarely have attempted to replicate important findings in their own work or that of others. Replication is essential to drawing robust scientific conclusions, especially in probabilistic systems with moderate to weak effects or a likelihood of bias. Last, researchers studying blue tit plumage have often developed ad hoc explanations for deviations of results from their predictions. Revising hypotheses in light of data is appropriate, but these revised hypotheses were rarely tested with new data. The only highly robust conclusion supported by meta-analysis is that male blue tits have plumage that reflects more light in the ultraviolet and yellow wavelengths than the plumage of females. Various other effects, including condition-dependence of plumage colour expression and a tendency for females to adjust the sex ratio of their offspring in response to male colour, remain uncertain. These obstacles to progress in the blue tit plumage literature are likely common in evolutionary biology, and so I recommend changes to incentive structures which may improve progress towards scientific understanding in this discipline. © 2012 The Authors. Biological Reviews © 2012 Cambridge Philosophical Society.

Supra-galactic colour patterns in globular cluster systems

NASA Astrophysics Data System (ADS)

Forte, Juan C.

2017-07-01

An analysis of globular cluster systems associated with galaxies included in the Virgo and Fornax Hubble Space Telescope-Advanced Camera Surveys reveals distinct (g - z) colour modulation patterns. These features appear on composite samples of globular clusters and, most evidently, in galaxies with absolute magnitudes Mg in the range from -20.2 to -19.2. These colour modulations are also detectable on some samples of globular clusters in the central galaxies NGC 1399 and NGC 4486 (and confirmed on data sets obtained with different instruments and photometric systems), as well as in other bright galaxies in these clusters. After discarding field contamination, photometric errors and statistical effects, we conclude that these supra-galactic colour patterns are real and reflect some previously unknown characteristic. These features suggest that the globular cluster formation process was not entirely stochastic but included a fraction of clusters that formed in a rather synchronized fashion over large spatial scales, and in a tentative time lapse of about 1.5 Gy at redshifts z between 2 and 4. We speculate that the putative mechanism leading to that synchronism may be associated with large scale feedback effects connected with violent star-forming events and/or with supermassive black holes.

Applications of machine-learning algorithms for infrared colour selection of Galactic Wolf-Rayet stars

NASA Astrophysics Data System (ADS)

Morello, Giuseppe; Morris, P. W.; Van Dyk, S. D.; Marston, A. P.; Mauerhan, J. C.

2018-01-01

We have investigated and applied machine-learning algorithms for infrared colour selection of Galactic Wolf-Rayet (WR) candidates. Objects taken from the Spitzer Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE) catalogue of the infrared objects in the Galactic plane can be classified into different stellar populations based on the colours inferred from their broad-band photometric magnitudes [J, H and Ks from 2 Micron All Sky Survey (2MASS), and the four Spitzer/IRAC bands]. The algorithms tested in this pilot study are variants of the k-nearest neighbours approach, which is ideal for exploratory studies of classification problems where interrelations between variables and classes are complicated. The aims of this study are (1) to provide an automated tool to select reliable WR candidates and potentially other classes of objects, (2) to measure the efficiency of infrared colour selection at performing these tasks and (3) to lay the groundwork for statistically inferring the total number of WR stars in our Galaxy. We report the performance results obtained over a set of known objects and selected candidates for which we have carried out follow-up spectroscopic observations, and confirm the discovery of four new WR stars.

Colour categories are reflected in sensory stages of colour perception when stimulus issues are resolved.

PubMed

Forder, Lewis; He, Xun; Franklin, Anna

2017-01-01

Debate exists about the time course of the effect of colour categories on visual processing. We investigated the effect of colour categories for two groups who differed in whether they categorised a blue-green boundary colour as the same- or different-category to a reliably-named blue colour and a reliably-named green colour. Colour differences were equated in just-noticeable differences to be equally discriminable. We analysed event-related potentials for these colours elicited on a passive visual oddball task and investigated the time course of categorical effects on colour processing. Support for category effects was found 100 ms after stimulus onset, and over frontal sites around 250 ms, suggesting that colour naming affects both early sensory and later stages of chromatic processing.

Colour categories are reflected in sensory stages of colour perception when stimulus issues are resolved

PubMed Central

He, Xun; Franklin, Anna

2017-01-01

Debate exists about the time course of the effect of colour categories on visual processing. We investigated the effect of colour categories for two groups who differed in whether they categorised a blue-green boundary colour as the same- or different-category to a reliably-named blue colour and a reliably-named green colour. Colour differences were equated in just-noticeable differences to be equally discriminable. We analysed event-related potentials for these colours elicited on a passive visual oddball task and investigated the time course of categorical effects on colour processing. Support for category effects was found 100 ms after stimulus onset, and over frontal sites around 250 ms, suggesting that colour naming affects both early sensory and later stages of chromatic processing. PMID:28542426

Effect of colour of drugs: systematic review of perceived effect of drugs and of their effectiveness.

PubMed

de Craen, A J; Roos, P J; de Vries, A L; Kleijnen, J

To assess the impact of the colour of a drug's formulation on its perceived effect and its effectiveness and to examine whether antidepressant drugs available in the Netherlands are different in colour from hypnotic, sedative, and anxiolytic drugs. Systematic review of 12 published studies. Six studies examined the perceived action of different coloured drugs and six the influence of the colour of a drug on its effectiveness. The colours of samples of 49 drugs affecting the central nervous system were assessed using a colour atlas. Perceived stimulant action versus perceived depressant action of colour of drugs; the trials that assessed the effect of drugs in different colours were done in patients with different diseases and had different outcome measures. The studies on perceived action of coloured drugs showed that red, yellow, and orange are associated with a stimulant effect, while blue and green are related to a tranquillising effect. The trials that assessed the impact of the colour of drugs on their effectiveness showed inconsistent differences between colours. The quality of the methods of these trials was variable. Hypnotic, sedative, and anxiolytic drugs were more likely than antidepressants to be green, blue, or purple. Colours affect the perceived action of a drug and seem to influence the effectiveness of a drug. Moreover, a relation exists between the colouring of drugs that affect the central nervous system and the indications for which they are used. Research contributing to a better understanding of the effect of the colour of drugs is warranted.

Display Parameters and Requirements

NASA Astrophysics Data System (ADS)

Bahadur, Birendra

The following sections are included: * INTRODUCTION * HUMAN FACTORS * Anthropometry * Sensory * Cognitive * Discussions * THE HUMAN VISUAL SYSTEM - CAPABILITIES AND LIMITATIONS * Cornea * Pupil and Iris * Lens * Vitreous Humor * Retina * RODS - NIGHT VISION * CONES - DAY VISION * RODS AND CONES - TWILIGHT VISION * VISUAL PIGMENTS * MACULA * BLOOD * CHOROID COAT * Visual Signal Processing * Pathways to the Brain * Spatial Vision * Temporal Vision * Colour Vision * Colour Blindness * DICHROMATISM * Protanopia * Deuteranopia * Tritanopia * ANOMALOUS TRICHROMATISM * Protanomaly * Deuteranomaly * Tritanomaly * CONE MONOCHROMATISM * ROD MONOCHROMATISM * Using Colour Effectively * COLOUR MIXTURES AND THE CHROMATICITY DIAGRAM * Colour Matching Functions and Chromaticity Co-ordinates * CIE 1931 Colour Space * CIE PRIMARIES * CIE COLOUR MATCHING FUNCTIONS AND CHROMATICITY CO-ORDINATES * METHODS FOR DETERMINING TRISTIMULUS VALUES AND COLOUR CO-ORDINATES * Spectral Power Distribution Method * Filter Method * CIE 1931 CHROMATICITY DIAGRAM * ADDITIVE COLOUR MIXTURE * CIE 1976 Chromaticity Diagram * CIE Uniform Colour Spaces and Colour Difference Formulae * CIELUV OR L*u*v* * CIELAB OR L*a*b* * CIE COLOUR DIFFERENCE FORMULAE * Colour Temperature and CIE Standard Illuminants and source * RADIOMETRIC AND PHOTOMETRIC QUANTITIES * Photopic (Vλ and Scotopic (Vλ') Luminous Efficiency Function * Photometric and Radiometric Flux * Luminous and Radiant Intensities * Incidence: Illuminance and Irradiance * Exitance or Emittance (M) * Luminance and Radiance * ERGONOMIC REQUIREMENTS OF DISPLAYS * ELECTRO-OPTICAL PARAMETERS AND REQUIREMENTS * Contrast and Contrast Ratio * Luminance and Brightness * Colour Contrast and Chromaticity * Glare * Other Aspects of Legibility * SHAPE AND SIZE OF CHARACTERS * DEFECTS AND BLEMISHES * FLICKER AND DISTORTION * ANGLE OF VIEW * Switching Speed * Threshold and Threshold Characteristic * Measurement Techniques For Electro-optical Parameters * RADIOMETRIC MEASUREMENTS * Broadband Radiometry or Filtered Photodetector Radiometric Method * Spectroradiometric Method * PHOTOMETRIC MEASUREMENTS * COLOUR MEASUREMENTS * LUMINANCE, CONTRAST RATIO, THRESHOLD CHARACTERISTIC AND POLAR PLOT * SWITCHING SPEED * ELECTRICAL AND LIFE PARAMETERS AND REQUIREMENTS * Operating Voltage, Current Drainage and Power Consumption * Operating Frequency * Life Expectancy * LCD FAILURE MODES * Liquid Crystal Materials * Substrate Glass * Electrode Patterns * Alignment and Aligning Material * Peripheral and End Plug Seal * Spacers * Crossover Material * Polarizers and Reflectors * Connectors * Heater * Colour Filters * Backlighting System * Explanation For Some of the Observed Defects * BLOOMING PIXELS * POLARIZER RELATED DEFECTS * DIFFERENTIAL THERMAL EXPANSION RELATED DEFECTS * ELECTROCHEMICAL AND ELECTROHYDRODYNAMIC RELATED DEFECTS * REVERSE TWIST AND REVERSE TILT * MEMORY OR REMINISCENT CONTRAST * LCD RELIABILRY AND ACCELERATED LIFE TESTING * ACKNOWLEDGEMENTS * REFERENCES * APPENDIX

Measuring the Hubble constant with Type Ia supernovae as near-infrared standard candles

NASA Astrophysics Data System (ADS)

Dhawan, Suhail; Jha, Saurabh W.; Leibundgut, Bruno

2018-01-01

The most precise local measurements of H0 rely on observations of Type Ia supernovae (SNe Ia) coupled with Cepheid distances to SN Ia host galaxies. Recent results have shown tension comparing H0 to the value inferred from CMB observations assuming ΛCDM, making it important to check for potential systematic uncertainties in either approach. To date, precise local H0 measurements have used SN Ia distances based on optical photometry, with corrections for light curve shape and colour. Here, we analyse SNe Ia as standard candles in the near-infrared (NIR), where luminosity variations in the supernovae and extinction by dust are both reduced relative to the optical. From a combined fit to 9 nearby calibrator SNe with host Cepheid distances from Riess et al. (2016) and 27 SNe in the Hubble flow, we estimate the absolute peak J magnitude MJ = -18.524 ± 0.041 mag and H0 = 72.8 ± 1.6 (statistical) ±2.7 (systematic) km s-1 Mpc-1. The 2.2% statistical uncertainty demonstrates that the NIR provides a compelling avenue to measuring SN Ia distances, and for our sample the intrinsic (unmodeled) peak J magnitude scatter is just 0.10 mag, even without light curve shape or colour corrections. Our results do not vary significantly with different sample selection criteria, though photometric calibration in the NIR may be a dominant systematic uncertainty. Our findings suggest that tension in the competing H0 distance ladders is likely not a result of supernova systematics that could be expected to vary between optical and NIR wavelengths, like dust extinction. We anticipate further improvements in H0 with a larger calibrator sample of SNe Ia with Cepheid distances, more Hubble flow SNe Ia with NIR light curves, and better use of the full NIR photometric data set beyond simply the peak J-band magnitude.

Machine learning in infrared object classification - an all-sky selection of YSO candidates

NASA Astrophysics Data System (ADS)

Marton, Gabor; Zahorecz, Sarolta; Toth, L. Viktor; Magnus McGehee, Peregrine; Kun, Maria

2015-08-01

Object classification is a fundamental and challenging problem in the era of big data. I will discuss up-to-date methods and their application to classify infrared point sources.We analysed the ALLWISE catalogue, the most recent public source catalogue of the Wide-field Infrared Survey Explorer (WISE) to compile a reliable list of Young Stellar Object (YSO) candidates. We tested and compared classical and up-to-date statistical methods as well, to discriminate source types like extragalactic objects, evolved stars, main sequence stars, objects related to the interstellar medium and YSO candidates by using their mid-IR WISE properties and associated near-IR 2MASS data.In the particular classification problem the Support Vector Machines (SVM), a class of supervised learning algorithm turned out to be the best tool. As a result we classify Class I and II YSOs with >90% accuracy while the fraction of contaminating extragalactic objects remains well below 1%, based on the number of known objects listed in the SIMBAD and VizieR databases. We compare our results to other classification schemes from the literature and show that the SVM outperforms methods that apply linear cuts on the colour-colour and colour-magnitude space. Our homogenous YSO candidate catalog can serve as an excellent pathfinder for future detailed observations of individual objects and a starting point of statistical studies that aim to add pieces to the big picture of star formation theory.

Photometric and spectroscopic study of low mass embedded star clusters in reflection nebulae

NASA Astrophysics Data System (ADS)

Soares, J. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

2005-02-01

An analysis of the candidate embedded stellar systems in the reflection nebulae vdBH-RN 26, vdBH-RN} 38, vdBH-RN} 53a, GGD 20, ESO 95-RN 18 and NGC 6595 is presented. Optical spectroscopic data from CASLEO (Argentina) in conjunction with near infrared photometry from the 2MASS Point Source Catalogue were employed. The analysis is based on source surface density, colour-colour and colour-magnitude diagrams together with theoretical pre-main sequence isochrones. We take into account the field population affecting the analysis by carrying out a statistical subtraction. The fundamental parameters for the stellar systems were derived. The resulting ages are in the range 1-4 Myr and the objects are dominated by pre-main sequence stars. The observed masses locked in the clusters are less than 25 M⊙. The studied systems have no stars of spectral types earlier than B, indicating that star clusters do not necessarily evolve through an HII region phase. The relatively small locked mass combined with the fact that they are not numerous in catalogues suggests that these low mass clusters are not important donors of stars to the field populations. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

Ultraviolet-B radiation modifies the quantitative and qualitative profile of flavonoids and amino acids in grape berries.

PubMed

Martínez-Lüscher, J; Torres, N; Hilbert, G; Richard, T; Sánchez-Díaz, M; Delrot, S; Aguirreolea, J; Pascual, I; Gomès, E

2014-06-01

Grapevine cv. Tempranillo fruit-bearing cuttings were exposed to supplemental ultraviolet-B (UV-B) radiation under controlled conditions, in order to study its effect on grape traits, ripening, amino acids and flavonoid profile. The plants were exposed to two doses of UV-B biologically effective (5.98 and 9.66kJm(-2)d(-1)), applied either from fruit set to ripeness or from the onset of veraison to ripeness. A 0kJm(-2)d(-1) treatment was included as a control. UV-B did not significantly modify grape berry size, but increased the relative mass of berry skin. Time to reach ripeness was not affected by UV-B, which may explain the lack of changes in technological maturity. The concentration of must extractable anthocyanins, colour density and skin flavonols were enhanced by UV-B, especially in plants exposed from fruit set. The quantitative and qualitative profile of grape skin flavonols were modified by UV-B radiation. Monosubstituted flavonols relative abundance increased proportionally to the accumulated UV-B doses. Furthermore, trisubstituted forms, which where predominant in non-exposed berries, were less abundant as UV-B exposure increased. Although total free amino acid content remained unaffected by the treatments, the increased levels of gamma-aminobutyric acid (GABA), as well as the decrease in threonine, isoleucine, methionine, serine and glycine, revealed a potential influence of UV-B on the GABA-mediated signalling and amino acid metabolism. UV-B had an overall positive impact on grape berry composition. Copyright © 2014 Elsevier Ltd. All rights reserved.

A search for ultraviolet-excess objects (Kondo, Noguchi, and Maehara 1984): Documentation for the machine-readable version

NASA Technical Reports Server (NTRS)

Warren, Wayne H., Jr.

1990-01-01

A list of 1186 ultraviolet-excess objects (designated KUV) was compiled as a result of a search conducted with the 105-cm Schmidt telescope of the Kiso station of the Tokyo Astronomical Observatory. This document describes the machine readable version of the KUV survey list and presents a sample listing showing the logical records as they are recorded in the machine readable catalog. The KUV data include equatorial coordinates, magnitudes, color indices, and identifications for previously cataloged objects.

Industrial-scale spray layer-by-layer assembly for production of biomimetic photonic systems.

PubMed

Krogman, K C; Cohen, R E; Hammond, P T; Rubner, M F; Wang, B N

2013-12-01

Layer-by-layer assembly is a powerful and flexible thin film process that has successfully reproduced biomimetic photonic systems such as structural colour. While most of the seminal work has been carried out using slow and ultimately unscalable immersion assembly, recent developments using spray layer-by-layer assembly provide a platform for addressing challenges to scale-up and manufacturability. A series of manufacturing systems has been developed to increase production throughput by orders of magnitude, making commercialized structural colour possible. Inspired by biomimetic photonic structures we developed and demonstrated a heat management system that relies on constructive reflection of near infrared radiation to bring about dramatic reductions in heat content.

Colour discrimination and categorisation in Williams syndrome.

PubMed

Farran, Emily K; Cranwell, Matthew B; Alvarez, James; Franklin, Anna

2013-10-01

Individuals with Williams syndrome (WS) present with impaired functioning of the dorsal visual stream relative to the ventral visual stream. As such, little attention has been given to ventral stream functions in WS. We investigated colour processing, a predominantly ventral stream function, for the first time in nineteen individuals with Williams syndrome. Colour discrimination was assessed using the Farnsworth-Munsell 100 hue test. Colour categorisation was assessed using a match-to-sample test and a colour naming task. A visual search task was also included as a measure of sensitivity to the size of perceptual colour difference. Results showed that individuals with WS have reduced colour discrimination relative to typically developing participants matched for chronological age; performance was commensurate with a typically developing group matched for non-verbal ability. In contrast, categorisation was typical in WS, although there was some evidence that sensitivity to the size of perceptual colour differences was reduced in this group. Copyright © 2013 Elsevier Ltd. All rights reserved.

Endocrine differences among colour morphs in a lizard with alternative behavioural strategies.

PubMed

Yewers, Madeleine St Clair; Jessop, Tim S; Stuart-Fox, Devi

2017-07-01

Alternative behavioural strategies of colour morphs are expected to associate with endocrine differences and to correspond to differences in physical performance (e.g. movement speed, bite force in lizards); yet the nature of correlated physiological and performance traits in colour polymorphic species varies widely. Colour morphs of male tawny dragon lizards Ctenophorus decresii have previously been found to differ in aggressive and anti-predator behaviours. We tested whether known behavioural differences correspond to differences in circulating baseline and post-capture stress levels of androgen and corticosterone, as well as bite force (an indicator of aggressive performance) and field body temperature. Immediately after capture, the aggressive orange morph had higher circulating androgen than the grey morph or the yellow morph. Furthermore, the orange morph maintained high androgen following acute stress (30min of capture); whereas androgen increased in the grey and yellow morphs. This may reflect the previously defined behavioural differences among morphs as the aggressive response of the yellow morph is conditional on the colour of the competitor and the grey morph shows consistently low aggression. In contrast, all morphs showed an increase in corticosterone concentration after capture stress and morphs did not differ in levels of corticosterone stress magnitude (CSM). Morphs did not differ in size- and temperature-corrected bite force but did in body temperature at capture. Differences in circulating androgen and body temperature are consistent with morph-specific behavioural strategies in C. decresii but our results indicate a complex relationship between hormones, behaviour, temperature and bite force within and between colour morphs. Copyright © 2017 Elsevier Inc. All rights reserved.

VizieR Online Data Catalog: 2nd and 3d parameters of HB of globular clusters (Gratton+, 2010)

NASA Astrophysics Data System (ADS)

Gratton, R. G.; Carretta, E.; Bragaglia, A.; Lucatello, S.; S'orazii, V.

2010-05-01

The second parameter (the first being metallicity) defining the distribution of stars on the horizontal branch (HB) of globular clusters (GCs) has long been one of the major open issues in our understanding of the evolution of normal stars. Large photometric and spectroscopic databases are now available: they include large and homogeneous sets of colour-magnitude diagrams, cluster ages, and homogeneous data about chemical compositions from our FLAMES survey. We use these databases to re-examine this issue. Methods. We use the photometric data to derive median and extreme (i.e., the values including 90% of the distribution) colours and magnitudes of stars along the HB for about a hundred GCs. We transform these into median and extreme masses of stars on the HB, using the models developed by the Pisa group, and taking into account evolutionary effects. We compare these masses with those expected at the tip of the red giant branch (RGB) to derive the total mass lost by the stars. (11 data files).

VizieR Online Data Catalog: Gaia photometry for white dwarfs (Carrasco+, 2014)

NASA Astrophysics Data System (ADS)

Carrasco, J. M.; Catalan, S.; Jordi, C.; Tremblay, P.-E.; Napiwotzki, R.; Luri, X.; Robin, A. C.; Kowalski, P. M.

2014-03-01

The Gaia space mission, through its 5-6 years survey of the whole sky up to magnitude V=20-25, will drastically increase the sample of known white dwarfs allowing to address new science questions. In this paper we provide a characterisation of Gaia photometry for the case of white dwarfs to better prepare for the analysis of the scientific output of the mission including relationships among colours involving Gaia magnitudes (white light G, blue GBP, red GRP and GRVS passbands) and colours from other commonly used photometric systems (Johnson-Cousins, SDSS and 2MASS). We also present numbers of white dwarfs predicted by the Gaia Universe Model Snapshot and compare them with an alternative simulation calibrated with the local white dwarfs sample. In these online tables we provide the values used to fit the relationships in the paper, especially useful for those cases where the deviation from the established relationships is large. The most recent Gaia transmission curves and three different compositions for white dwarfs were considered here (pure hydrogen, pure helium and mixed composition with H/He=0.1). (3 data files).

Col-OSSOS: A new ugrJ taxonomy for trans-Neptunian objects

NASA Astrophysics Data System (ADS)

Fraser, Wesley Cristopher; Bannister, Michele T.; Marsset, Michael; Pike, Rosemary E.; Schwamb, Megan E.; Kavelaars, J. J.; Benecchi, Susan D.; Delsanti, Audrey; Lehner, Matt J.; Wang, Shiang-Yu; Thirouin, Audrey; Guilbert-Lepoutre, Aurelie; Peixinho, Nuno; Vernazza, Pierre

2016-10-01

The surfaces of trans-Neptunian objects (TNOs) are poorly understood. Very little has been discerned about the compositions of most small TNOs. In recent years however, some concrete knowledge about the surface colour distribution of TNOs has come to light. It is now generally accepted that small TNOs fall into at least three classes of object based on their surface colours and albedo. Despite nearly two decades of gathering TNO surface information however, a taxonomy has still not been agreed upon. From Col-OSSOS u, g, r, and J photometry, we find significantly different clustering of (u-g) colour in the optically red, dynamically cold TNOs as compared to similarly optically coloured dynamically excited TNOs. One of the goals of the Colours of the Outer Solar System Origins Survey is the development of a robust TNO taxonomy. This 4 year program which started in 2014B is simultaneously using the Gemini-North and Canada-France-Hawaii telescopes to gather near simultaneous u, g, r, and J spectral photometry of all targets in the Outer Solar System Origins Survey (OSSOS) brighter than r'=23.6 (120 expected). The focus of Col-OSSOS is completeness and consistency, with the same SNR=25 being reached in all bands, for all targets brighter than our depth limit. Col-OSSOS will provide the first brightness-complete, compositional-dynamical map of the Outer Solar System, from which key hypotheses about the Solar System's cosmogony can be tested. After an overview of the survey's design and techniques, we will present the observed colours from the first complete block. Even with just ~30 targets, the precise photometry afforded by Col-OSSOS has already revealed the existence of 3 separate TNO taxons or classes, which become obvious when their (u-g), (g-r), and (r-J) colours are considered together. In particular, the so-called cold classical TNOs, which stand out because of their dynamically quiescent orbits, while possessing similar (g-r) and (r-J) colours as other red TNOs, exhibit extremely red (u-g) colours, roughly 0.5 magnitudes redder than the typical (u-g) of the red dynamically excited objects. These classes appear to exhibit a continuum in colour, rather than occupying similar mean colours for all class members.

Epitaxial graphene/SiC Schottky ultraviolet photodiode with orders of magnitude adjustability in responsivity and response speed

NASA Astrophysics Data System (ADS)

Yang, Junwei; Guo, Liwei; Guo, Yunlong; Hu, Weijie; Zhang, Zesheng

2018-03-01

A simple optical-electronic device that possesses widescale adjustability in its performance is specially required for realizing multifunctional applications as in optical communication and weak signal detectors. Here, we demonstrate an epitaxial graphene (EG)/n-type SiC Schottky ultraviolet (UV) photodiode with extremely widescale adjustability in its responsivity and response speed. It is found that the response speed of the device can be modulated over seven orders of magnitude from tens of nanoseconds to milliseconds by changing its working bias from 0 to -5 V, while its responsivity can be varied by three orders of magnitude. A 2.18 A/W responsivity is observed at -5 V when a 325 nm laser is irradiated on, corresponding to an external quantum efficiency over 800% ascribed to the trap induced internal gain mechanism. These performances of the EG/SiC Schottky photodiode are far superior to those based on traditional metal/SiC and indicate that the EG/n-type SiC Schottky diode is a good candidate for application in UV photodetection.

The inter-outburst behavior of cataclysmic variables

NASA Technical Reports Server (NTRS)

Szkody, Paula; Mattei, Janet A.; Waagen, Elizabeth O.; Stablein, Clay

1990-01-01

Existing International Ultraviolet Explorer (IUE) and American Association of Variable Star Observers (AAVSO) archive data was used to accomplish a large scale study of what happens to the ultraviolet flux of accretion disk systems during the quiescent intervals between outbursts and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 novae along with existing optical coverage. Results indicate that most systems show correlated ultraviolet (UV) flux behavior with interoutburst phase, with 60 percent of the dwarf novae and 50 percent of the novae having decreasing flux trends while 33 percent of the dwarf novae and 38 percent of the novae show rising UV flux during the quiescent interval. All of the dwarf novae with decreasing UV fluxes at 1475A have orbital periods longer than 4.4 hours, while all (except BV Cen) with flat or rising fluxes at 1475A have orbital periods less than two hours. There are not widespread correlations of the UV fluxes with the amplitude of the preceding outburst and no correlations with the width of the outburst. From a small sample (7) that have relatively large quiescent V magnitude changes between the IUE observations, most show a strong correlation between the UV and optical continuum. Interpretation of the results is complicated by not being able to determine how much the white dwarf contributes to the ultraviolet flux. However, it is now evident that noticeable changes are occurring in the hot zones in accreting systems long after the outburst, and not only for systems that are dominated by the white dwarf. Whether these differences are due to different outburst mechanisms or to changes on white dwarfs which provide varying contributions to the UV flux remains to be determined.

Adhesion enhancement of biomimetic dry adhesives by nanoparticle in situ synthesis

NASA Astrophysics Data System (ADS)

Díaz Téllez, J. P.; Harirchian-Saei, S.; Li, Y.; Menon, C.

2013-10-01

A novel method to increase the adhesion strength of a gecko-inspired dry adhesive is presented. Gold nanoparticles are synthesized on the tips of the microfibrils of a polymeric dry adhesive to increase its Hamaker constant. Formation of the gold nanoparticles is qualitatively studied through a colour change in the originally transparent substance and quantitatively analysed using ultraviolet-visible spectrophotometry. A pull-off force test is employed to quantify the adhesion enhancement. Specifically, adhesion forces of samples with and without embedded gold nanoparticles are measured and compared. The experimental results indicate that an adhesion improvement of 135% can be achieved.

Use of discrete chromatic space to tune the image tone in a color image mosaic

NASA Astrophysics Data System (ADS)

Zhang, Zuxun; Li, Zhijiang; Zhang, Jianqing; Zheng, Li

2003-09-01

Color image process is a very important problem. However, the main approach presently of them is to transfer RGB colour space into another colour space, such as HIS (Hue, Intensity and Saturation). YIQ, LUV and so on. Virutally, it may not be a valid way to process colour airborne image just in one colour space. Because the electromagnetic wave is physically altered in every wave band, while the color image is perceived based on psychology vision. Therefore, it's necessary to propose an approach accord with physical transformation and psychological perception. Then, an analysis on how to use relative colour spaces to process colour airborne photo is discussed and an application on how to tune the image tone in colour airborne image mosaic is introduced. As a practice, a complete approach to perform the mosaic on color airborne images via taking full advantage of relative color spaces is discussed in the application.

VizieR Online Data Catalog: SN 2007on and SN 2011iv light curves (Gall+, 2018)

NASA Astrophysics Data System (ADS)

Gall, C.; Stritzinger, M. D.; Ashall, C.; Baron, E.; Burns, C. R.; Hoeflich, P.; Hsiao, E. Y.; Mazzali, P. A.; Phillips, M. M.; Filippenko, A. V.; Anderson, J. P.; Benetti, S.; Brown, P. J.; Campillay, A.; Challis, P.; Contreras, C.; Elias de La Rosa, N.; Folatelli, G.; Foley, R. J.; Fraser, M.; Holmbo, S.; Marion, G. H.; Morrell, N.; Pan, Y.-C.; Pignata, G.; Suntzeff, N. B.; Taddia, F.; Torres Robledo, S.; Valenti, S.

2017-11-01

Detailed optical and NIR light curves of SN 2007on obtained by the first phase of the Carnegie Supernova Project (CSP-I, 2004-2009; Hamuy et al., 2006PASP..118....2H) were published by Stritzinger et al. (2011, Cat. J/AJ/142/156).UV uvw2-, uvm2-, and uvw1-band imaging of both SN 2007on and SN 2011iv were obtained with Swift (+ UVOT). Photome- try of SN 2007on and SN 2011iv was computed following the method described in detail by Brown et al. (2014Ap&SS.354...89B), who use the calibration published by Breeveld et al. (2011, AIPCS, 1358, 373). The Swift UVOT images and photometry are also available as part of the Swift Optical Ultraviolet Supernova Archive (SOUSA; Brown et al. 2014Ap&SS.354...89B). Optical ugriBV-band imaging of SN 2007on and SN 2011iv was obtained with the Henrietta Swope 1.0m telescope (+ SITe3 direct CCD camera) located at the Las Campanas Observatory (LCO). The NIR YJH-band imaging of SN 2007on was obtained with the Swope (+ RetroCam) and the Irenee du Pont 2.5m (+ WIRC: Wide Field Infrared Camera) telescopes (Stritzinger et al., Cat. J/AJ/142/156), while in the case of SN 2011iv all NIR YJH-band imaging was taken with RetroCam attached to the Irenee du Pont telescope. The optical local sequence is calibrated relative to Landolt (1992AJ....104..372L) (BV) and Smith et al. (2002AJ....123.2121S) (ugri) standard-star fields observed over multiple photometric nights. The NIR J-band and H-band local sequences were calibrated relative to the Persson et al. (1998AJ....116.2475P) standard stars, while the Y- band local sequence was calibrated relative to standard Y-band magnitudes computed using a combination of stellar atmosphere models (Castelli & Kurucz, 2003, IAUSymp, 210, A20) with the J-Ks colours of the Persson et al. standard-star catalogue (Hamuy et al., 2006PASP..118....2H). (5 data files).

Study of II Galactic quadrant of Milky Way Galaxy using open clusters

NASA Astrophysics Data System (ADS)

Bisht, Devendra; Ganesh, Shashikiran; Baliyan, Kiran Singh; Yadav, Ramakant Singh; Durgapal, Alok

2018-04-01

We have made UBV I CCD observations for the open clusters Teutsch 1, Riddle 4 and Czernik 6 using 1.04-m Sampurnanand telescope located at the ARIES observatory (Manora peak, Nainital, India). We have used 2MASS JHKS data for the clusters Teutsch 126, Teutsch 54 and Czernik 3. For the estimation of fundamental parameters, we have plotted radial density profiles, colour-magnitude and colour-colour diagrams. Using these inputs, we have studied the structure of Milky Way Galaxy in the second Galactic quadrant. We have considered the open clusters that are younger than 1 Gyrs and lay in the longitude range from 90 to 180 deg. Our study shows that up to 3.5 Kpc, the Galactic disc bends towards the southern hemisphere while after 3.5 Kpc it bends towards the northern hemisphere. The distribution of reddening with longitude and age shows a decreasing trend with the longitude and age of the clusters. Our study also indicates that younger clusters have more reddening than older ones.

High-intensity double-pulse X-ray free-electron laser

DOE PAGES

Marinelli, A.; Ratner, D.; Lutman, A. A.; ...

2015-03-06

The X-ray free-electron laser has opened a new era for photon science, improving the X-ray brightness by ten orders of magnitude over previously available sources. Similar to an optical laser, the spectral and temporal structure of the radiation pulses can be tailored to the specific needs of many experiments by accurately manipulating the lasing medium, that is, the electron beam. Here we report the generation of mJ-level two-colour hard X-ray pulses of few femtoseconds duration with an XFEL driven by twin electron bunches at the Linac Coherent Light Source. This performance represents an improvement of over an order of magnitudemore » in peak power over state-of-the-art two-colour XFELs. The unprecedented intensity and temporal coherence of this new two-colour X-ray free-electron laser enable an entirely new set of scientific applications, ranging from X-ray pump/X-ray probe experiments to the imaging of complex biological samples with multiple wavelength anomalous dispersion.« less

VizieR Online Data Catalog: OB association members in ACT+TRC Catalogs (Hoogerwerf, 2000)

NASA Astrophysics Data System (ADS)

Hoogerwerf, R.

2000-05-01

The Hipparcos Catalogue (Cat. I/239) contains members of nearby OB associations brighter than 12th magnitude in V. However, membership lists are complete only to magnitude V=7.3. In this paper we discuss whether proper motions listed in the `Astrographic Catalogue+Tycho' reference catalogue (ACT, Cat. I/246) and the Tycho Reference Catalogue (TRC, Cat. I/250), which are complete to V~10.5mag, can be used to find additional association members. Proper motions in the ACT/TRC have an average accuracy of ~3mas/yr. We search for ACT/TRC stars which have proper motions consistent with the spatial velocity of the Hipparcos members of the nearby OB associations already identified by de Zeeuw et al. (1999, Cat. J/AJ/117/354). These stars are first selected using a convergent-point method, and then subjected to further constraints on the proper-motion distribution, magnitude and colour to narrow down the final number of candidate members. Monte Carlo simulations show that the proper-motion distribution, magnitude, and colour constraints remove ~97% of the field stars, while at the same time retain more than 90% of the cluster stars. The procedure has been applied to five nearby associations: the three subgroups of Sco OB2, plus Per OB3 and Cep OB6. In all cases except Cep OB6, we find evidence for new association members fainter than the completeness limit of the Hipparcos Catalogue. However, narrow-band photometry and/or radial velocities are needed to pinpoint the cluster members, and to study their physical characteristics. (1 data file).

Colour vision experimental studies in teaching of optometry

NASA Astrophysics Data System (ADS)

Ozolinsh, Maris; Ikaunieks, Gatis; Fomins, Sergejs

2005-10-01

Following aspects related to human colour vision are included in experimental lessons for optometry students of University of Latvia. Characteristics of coloured stimuli (emitting and reflective), determination their coordinates in different colour spaces. Objective characteristics of transmitting of colour stimuli through the optical system of eye together with various types of appliances (lenses, prisms, Fresnel prisms). Psychophysical determination of mono- and polychromatic stimuli perception taking into account physiology of eye, retinal colour photoreceptor topography and spectral sensitivity, spatial and temporal characteristics of retinal receptive fields. Ergonomics of visual perception, influence of illumination and glare effects, testing of colour vision deficiencies.

Young star clusters in the interacting galaxies of Hickson Compact Group 90

NASA Astrophysics Data System (ADS)

Miah, J. A.; Sharples, R. M.; Cho, J.

2015-03-01

Deep images of Hickson Compact Group 90 (HCG 90) have been obtained using the Advanced Camera for Surveys on the Hubble Space Telescope. We report results for star clusters observed in the interacting pair of galaxies NGC 7174 and NGC 7176. We present magnitude and colour distributions for the observed cluster population and find that the majority of objects show colours similar to intermediate/old age (>1 Gyr) globular clusters. However, a significant population of blue star clusters are also observed which may have formed from the tidal interaction currently occurring between the two galaxies. We find luminosity function turnover magnitudes of m^{TO}g = 25.1 ± 0.1 and m^{TO}z = 24.3 ± 0.1 for the g and z bands, respectively, implying distances of Dg = 28.8 ± 2.6 Mpc and Dz = 34.7 ± 3.1 Mpc to these galaxies, using the globular cluster luminosity function method. Lastly, we determine a total cluster population of approximately NGC ≃ 212 ± 10 over all magnitudes and a low specific frequency of SN ˜ 0.6 ± 0.1 for this pair of interacting elliptical and spiral galaxies. The small globular cluster population is likely due to tidal interactions taking place between the two galaxies which may have stripped many progenitor clusters away and formed the diffuse light observed at the core of HCG 90.

Quasar probabilities and redshifts from WISE mid-IR through GALEX UV photometry

NASA Astrophysics Data System (ADS)

DiPompeo, M. A.; Bovy, J.; Myers, A. D.; Lang, D.

2015-09-01

Extreme deconvolution (XD) of broad-band photometric data can both separate stars from quasars and generate probability density functions for quasar redshifts, while incorporating flux uncertainties and missing data. Mid-infrared photometric colours are now widely used to identify hot dust intrinsic to quasars, and the release of all-sky WISE data has led to a dramatic increase in the number of IR-selected quasars. Using forced photometry on public WISE data at the locations of Sloan Digital Sky Survey (SDSS) point sources, we incorporate this all-sky data into the training of the XDQSOz models originally developed to select quasars from optical photometry. The combination of WISE and SDSS information is far more powerful than SDSS alone, particularly at z > 2. The use of SDSS+WISE photometry is comparable to the use of SDSS+ultraviolet+near-IR data. We release a new public catalogue of 5537 436 (total; 3874 639 weighted by probability) potential quasars with probability PQSO > 0.2. The catalogue includes redshift probabilities for all objects. We also release an updated version of the publicly available set of codes to calculate quasar and redshift probabilities for various combinations of data. Finally, we demonstrate that this method of selecting quasars using WISE data is both more complete and efficient than simple WISE colour-cuts, especially at high redshift. Our fits verify that above z ˜ 3 WISE colours become bluer than the standard cuts applied to select quasars. Currently, the analysis is limited to quasars with optical counterparts, and thus cannot be used to find highly obscured quasars that WISE colour-cuts identify in significant numbers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inserra, C.; Smartt, S. J., E-mail: c.inserra@qub.ac.uk

We investigate the use of type Ic superluminous supernovae (SLSN Ic) as standardizable candles and distance indicators. Their appeal as cosmological probes stems from their remarkable peak luminosities, hot blackbody temperatures, and bright rest-frame ultraviolet emission. We present a sample of 16 published SLSN, from redshifts 0.1 to 1.2, and calculate accurate K corrections to determine uniform magnitudes in 2 synthetic rest-frame filter bandpasses with central wavelengths at 400 nm and 520 nm. At 400 nm, we find an encouragingly low scatter in their uncorrected, raw mean magnitudes with M(400) = –21.86 ± 0.35 mag for the full sample ofmore » 16 objects. We investigate the correlation between their decline rates and peak magnitude and find that the brighter events appear to decline more slowly. In a manner similar to the Phillips relation for type Ia SNe (SNe Ia), we define a ΔM {sub 20} decline relation. This correlates peak magnitude and decline over 20 days and can reduce the scatter in standardized peak magnitudes to ±0.22 mag. We further show that M(400) appears to have a strong color dependence. Redder objects are fainter and also become redder faster. Using this peak magnitudecolor evolution relation, a surprisingly low scatter of between ±0.08 mag and ±0.13 mag can be found in peak magnitudes, depending on sample selection. However, we caution that only 8 to 10 objects currently have enough data to test this peak magnitudecolor evolution relation. We conclude that SLSN Ic are promising distance indicators in the high-redshift universe in regimes beyond those possible with SNe Ia. Although the empirical relationships are encouraging, the unknown progenitor systems, how they may evolve with redshift, and the uncertain explosion physics are of some concern. The two major measurement uncertainties are the limited numbers of low-redshift, well-studied objects available to test these relationships and internal dust extinction in the host galaxies.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wuebbles, D.J.; Kinnison, D.E.; Lean, J.L.

Over the past decade, knowledge of the magnitude and temporal structure of the variations in the sun's ultraviolet irradiance has increased steadily. A number of theoretical modeling studies have shown that changes in the solar ultraviolet flux during the 11-year solar cycle can have a significant effect on stratospheric ozone concentrations. With the exception of Brasseur et al., who examined a very broad range of solar flux variations, all of these studies assumed much larger changes in the ultraviolet flux than measurements now indicate. These studies either calculated the steady-state effect at solar maximum and solar minimum or assumed sinusoidalmore » variations in the solar flux changes with time. It is now possible to narrow the uncertainty range of the expected effects on upper stratospheric ozone and temperature resulting from the 11-year solar cycle. A more accurate representation of the solar flux changes with time is used in this analysis, as compared to previous published studies. This study also evaluates the relative roles of solar flux variations and increasing concentrations of long-lived trace gases in determining the observed trends in upper stratospheric ozone and temperature. The LLNL two-dimensional chemical-radiative-transport model of the global atmosphere is used to evaluate the combined effects on the stratosphere from changes in solar ultraviolet irradiances and trace gas concentrations over the last several decades. Derived trends in upper stratospheric ozone concentrations and temperature are then compared with available analyses of ground-based and satellite measurements over this time period.« less

Unbiased estimates of galaxy scaling relations from photometric redshift surveys

NASA Astrophysics Data System (ADS)

Rossi, Graziano; Sheth, Ravi K.

2008-06-01

Many physical properties of galaxies correlate with one another, and these correlations are often used to constrain galaxy formation models. Such correlations include the colour-magnitude relation, the luminosity-size relation, the fundamental plane, etc. However, the transformation from observable (e.g. angular size, apparent brightness) to physical quantity (physical size, luminosity) is often distance dependent. Noise in the distance estimate will lead to biased estimates of these correlations, thus compromising the ability of photometric redshift surveys to constrain galaxy formation models. We describe two methods which can remove this bias. One is a generalization of the Vmax method, and the other is a maximum-likelihood approach. We illustrate their effectiveness by studying the size-luminosity relation in a mock catalogue, although both methods can be applied to other scaling relations as well. We show that if one simply uses photometric redshifts one obtains a biased relation; our methods correct for this bias and recover the true relation.

Determinants of Colour Constancy and the Blue Bias

PubMed Central

Gegenfurtner, Karl

2017-01-01

We investigated several sensory and cognitive determinants of colour constancy across 40 illumination hues. In the first experiment, we measured colour naming for the illumination and for the colour induced by the illumination on the colorimetric grey. Results confirmed that the induced colours are approximately complementary to the colour of the illumination. In the second experiment, we measured colour constancy using achromatic adjustments. Average colour constancy was perfect under the blue daylight illumination and decreased in colour directions away from the blue daylight illumination due to undershooting and a strong blue bias. Apart from this blue bias, colour constancy was not related to illumination discrimination and to chromatic detection measured previously with the same setup and stimuli. We also observed a strong negative relationship between the degree of colour constancy and the consensus of naming the illumination colour. Constancy coincided with a low naming consensus, in particular because bluish illumination colours were sometimes seen as achromatic. Blue bias and category consensus alone explained >68%, and all determinants together explained >94% of the variance of achromatic adjustments. These findings suggest that colour constancy is optimised for blue daylight. PMID:29348910

A Novel Method for Age Estimation in Solar-Type Stars Through GALEX FUV Magnitudes

NASA Astrophysics Data System (ADS)

Ho, Kelly; Subramonian, Arjun; Smith, Graeme; Shouru Shieh

2018-01-01

Utilizing an inverse association known to exist between Galaxy Evolution Explorer (GALEX) far ultraviolet (FUV) magnitudes and the chromospheric activity of F, G, and K dwarfs, we explored a method of age estimation in solar-type stars through GALEX FUV magnitudes. Sample solar-type star data were collected from refereed publications and filtered by B-V and absolute visual magnitude to ensure similarities in temperature and luminosity to the Sun. We determined FUV-B and calculated a residual index Q for all the stars, using the temperature-induced upper bound on FUV-B as the fiducial. Plotting current age estimates for the stars against Q, we discovered a strong and significant association between the variables. By applying a log-linear transformation to the data to produce a strong correlation between Q and loge Age, we confirmed the association between Q and age to be exponential. Thus, least-squares regression was used to generate an exponential model relating Q to age in solar-type stars, which can be used by astronomers. The Q-method of stellar age estimation is simple and more efficient than existing spectroscopic methods and has applications to galactic archaeology and stellar chemical composition analysis.

Thin film filter lifetesting results in the extreme ultraviolet

NASA Technical Reports Server (NTRS)

Vedder, P. W.; Vallerga, J. V.; Gibson, J. L.; Stock, J.; Siegmund, O. H. W.

1993-01-01

We present the results of the thin film filter lifetesting program conducted as part of the NASA Extreme Ultraviolet Explorer (EUVE) satellite mission. This lifetesting program is designed to monitor changes in the transmission and mechanical properties of the EUVE filters over the lifetime of the mission (fabrication, assembly, launch and operation). Witness test filters were fabricated from thin film foils identical to those used in the flight filters. The witness filters have been examined and calibrated periodically over the past seven years. The filters have been examined for evidence of pinholing, mechanical degradation, and oxidation. Absolute transmissions of the flight and witness filters have been measured in the extreme ultraviolet (EUV) over six orders of magnitude at numerous wavelengths using the Berkeley EUV Calibration Facility.

The effect of growth rate and ageing on colour variation of European pond turtles.

PubMed

Ibáñez, Alejandro; Martín, José; Marzal, Alfonso; Bertolero, Albert

2017-06-01

Many chelonians have colourful dots, patches and stripes throughout their body that are made up, at least in part, of carotenoids. Therefore, turtles are very suitable models to study the evolution and functionality of carotenoid-based colouration. Recent studies suggested a close link between colouration and immune system in these taxa. However, more research is needed to understand the role of these colourful stripes and patches in turtle visual signalling. The purpose of this study was to explore the relationship between growth rate and colouration in European pond turtles. In particular, we wanted to answer the question of whether there is a trade-off between growth and colour expression. We also aimed to explore the effect of body size and age on colour variation. Turtles from a reintroduction-breeding program were recaptured, weighed and measured over an 8-year period to estimate their growth rates and age. We also measured with a spectrometer the reflectance of colour patches in two different body parts: shell and forelimb. We found that turtles with a faster growth rate had brighter limb stripes independently of their age. On the other hand, shell colouration was related to body size with larger turtles having brighter shell stripes and higher values of carotenoid chroma. Our results suggest that fast-growers may afford to express intense colourful limb stripes likely due to their higher intake of carotenoids that would modulate both growth and colour expression. However, shell colouration was related to body size probably due to ontogenetic differences in the diet, as juveniles are strictly carnivorous while adults are omnivorous. Alternatively, shell colouration might be involved in crypsis as the shell is visually exposed to predators.

The effect of growth rate and ageing on colour variation of European pond turtles

NASA Astrophysics Data System (ADS)

Ibáñez, Alejandro; Martín, José; Marzal, Alfonso; Bertolero, Albert

2017-06-01

Many chelonians have colourful dots, patches and stripes throughout their body that are made up, at least in part, of carotenoids. Therefore, turtles are very suitable models to study the evolution and functionality of carotenoid-based colouration. Recent studies suggested a close link between colouration and immune system in these taxa. However, more research is needed to understand the role of these colourful stripes and patches in turtle visual signalling. The purpose of this study was to explore the relationship between growth rate and colouration in European pond turtles. In particular, we wanted to answer the question of whether there is a trade-off between growth and colour expression. We also aimed to explore the effect of body size and age on colour variation. Turtles from a reintroduction-breeding program were recaptured, weighed and measured over an 8-year period to estimate their growth rates and age. We also measured with a spectrometer the reflectance of colour patches in two different body parts: shell and forelimb. We found that turtles with a faster growth rate had brighter limb stripes independently of their age. On the other hand, shell colouration was related to body size with larger turtles having brighter shell stripes and higher values of carotenoid chroma. Our results suggest that fast-growers may afford to express intense colourful limb stripes likely due to their higher intake of carotenoids that would modulate both growth and colour expression. However, shell colouration was related to body size probably due to ontogenetic differences in the diet, as juveniles are strictly carnivorous while adults are omnivorous. Alternatively, shell colouration might be involved in crypsis as the shell is visually exposed to predators.

Semantically Induced Distortions of Visual Awareness in a Patient with Balint's Syndrome

ERIC Educational Resources Information Center

Soto, David; Humphreys, Glyn W.

2009-01-01

We present data indicating that visual awareness for a basic perceptual feature (colour) can be influenced by the relation between the feature and the semantic properties of the stimulus. We examined semantic interference from the meaning of a colour word ("RED") on simple colour (ink related) detection responses in a patient with simultagnosia…

Selective interference reveals dissociation between memory for location and colour.

PubMed

Vuontela, V; Rämä, P; Raninen, A; Aronen, H J; Carlson, S

1999-08-02

The aim was to study whether there is indication of a dissociation in processing of visuospatial and colour information in working memory in humans. Experimental subjects performed visuospatial and colour n-back tasks with and without visuospatial and colour distractive stimuli presented in the middle of the delay period to specifically affect mnemonic processing of task-related information. In the high memory-load condition, the visuospatial, but not the colour, task was selectively disrupted by visuospatial but not colour distractors. When subvocal rehearsal of the memoranda in the colour task was prevented by articulatory suppression; colour task performance was also selectively disrupted by distractors qualitatively similar to the memoranda. The results support the suggestion that visual working memory for location is processed separate from that for colour.

Neural activation patterns and connectivity in visual attention during Number and Non-number processing: An ERP study using the Ishihara pseudoisochromatic plates.

PubMed

Al-Marri, Faraj; Reza, Faruque; Begum, Tahamina; Hitam, Wan Hazabbah Wan; Jin, Goh Khean; Xiang, Jing

2017-10-25

Visual cognitive function is important to build up executive function in daily life. Perception of visual Number form (e.g., Arabic digit) and numerosity (magnitude of the Number) is of interest to cognitive neuroscientists. Neural correlates and the functional measurement of Number representations are complex occurrences when their semantic categories are assimilated with other concepts of shape and colour. Colour perception can be processed further to modulate visual cognition. The Ishihara pseudoisochromatic plates are one of the best and most common screening tools for basic red-green colour vision testing. However, there is a lack of study of visual cognitive function assessment using these pseudoisochromatic plates. We recruited 25 healthy normal trichromat volunteers and extended these studies using a 128-sensor net to record event-related EEG. Subjects were asked to respond by pressing Numbered buttons when they saw the Number and Non-number plates of the Ishihara colour vision test. Amplitudes and latencies of N100 and P300 event related potential (ERP) components were analysed from 19 electrode sites in the international 10-20 system. A brain topographic map, cortical activation patterns and Granger causation (effective connectivity) were analysed from 128 electrode sites. No major significant differences between N100 ERP components in either stimulus indicate early selective attention processing was similar for Number and Non-number plate stimuli, but Non-number plate stimuli evoked significantly higher amplitudes, longer latencies of the P300 ERP component with a slower reaction time compared to Number plate stimuli imply the allocation of attentional load was more in Non-number plate processing. A different pattern of asymmetric scalp voltage map was noticed for P300 components with a higher intensity in the left hemisphere for Number plate tasks and higher intensity in the right hemisphere for Non-number plate tasks. Asymmetric cortical activation and connectivity patterns revealed that Number recognition occurred in the occipital and left frontal areas where as the consequence was limited to the occipital area during the Non-number plate processing. Finally, the results displayed that the visual recognition of Numbers dissociates from the recognition of Non-numbers at the level of defined neural networks. Number recognition was not only a process of visual perception and attention, but it was also related to a higher level of cognitive function, that of language.

A Supernova in ZWI:16.7+1.57

NASA Astrophysics Data System (ADS)

Shahbazian, R. K.; Borngen, F.

1984-09-01

A supernova near the galaxy Zw1 16.7+1.57, has been found on the maps of the Palomar Observatory. The eye estimation of photographic and red magnitudes gives: mpg = 18.3, mr = 18.6. The blue colour and the supposed luminosity (Mpg = -17.2) of the object suggest that it is of type II near the maximum.

Chromotherapy of macular degeneration with transitions lenses and green-yellow medical filters and special programme for psychoorganic disturbances.

PubMed

Vojniković, Bozo; Vojniković, Davor

2010-04-01

Optical spectrum of the sunlight consists of visible or chromatic spectrum, with the range of wavelengths of electromagnetic vibrations from 7700 to 3900 AU, and the invisible spectrum: infrared and ultraviolet. Chromatic spectrum gives rise to the sensation of colour, capable for simulating specialized retinal photoreceptors and is perceptible as light. This rule of perception of the particular range of the optical spectrum goes mainly for man, while particular deviations, more or less, are applicable to the rest of animal and plant life. The optical part of the spectrum belongs to nonionizing radiation. It created the life on the Earth, maintaining it nowadays and even threatening the human organ of vision, because the retina had not been yet adequately accommodated through evolution with its photoreactive metabolism. Human retina is very sensitive about possible harmful influence of ultraviolet and blue light even today in evolution, but also phototoxic on complete strong visible light. In their clinical and experimental work on animals, the authors prove with their own patent (P 20020077A)-Vojniković B&D, and in collaboration with Essilor Optic Austria GmbH, that particular medical filters in the range of green-yellow colour especially (565 to 570 nm), and in combination with "Transitions" successfully threat macular degeneration-AMD, slowing down its progression and having positive psychoorganic effect on the depressive mood of such patients with threatened sight. Full attention has been paid to the design of medical filter, so the periphery of the lens plays a positive role in blood concentration of melatonin, while the central part stimulates the sight and the concentration of serotonine. Thus the physiological balance of melatonin and serotonin and the stability of psychophysical disturbances have been achieved.

Ultraviolet vision in lacertid lizards: evidence from retinal structure, eye transmittance, SWS1 visual pigment genes and behaviour.

PubMed

Pérez i de Lanuza, Guillem; Font, Enrique

2014-08-15

Ultraviolet (UV) vision and UV colour patches have been reported in a wide range of taxa and are increasingly appreciated as an integral part of vertebrate visual perception and communication systems. Previous studies with Lacertidae, a lizard family with diverse and complex coloration, have revealed the existence of UV-reflecting patches that may function as social signals. However, confirmation of the signalling role of UV coloration requires demonstrating that the lizards are capable of vision in the UV waveband. Here we use a multidisciplinary approach to characterize the visual sensitivity of a diverse sample of lacertid species. Spectral transmission measurements of the ocular media show that wavelengths down to 300 nm are transmitted in all the species sampled. Four retinal oil droplet types can be identified in the lacertid retina. Two types are pigmented and two are colourless. Fluorescence microscopy reveals that a type of colourless droplet is UV-transmitting and may thus be associated with UV-sensitive cones. DNA sequencing shows that lacertids have a functional SWS1 opsin, very similar at 13 critical sites to that in the presumed ancestral vertebrate (which was UV sensitive) and other UV-sensitive lizards. Finally, males of Podarcis muralis are capable of discriminating between two views of the same stimulus that differ only in the presence/absence of UV radiance. Taken together, these results provide convergent evidence of UV vision in lacertids, very likely by means of an independent photopigment. Moreover, the presence of four oil droplet types suggests that lacertids have a four-cone colour vision system. © 2014. Published by The Company of Biologists Ltd.

Saliency predicts change detection in pictures of natural scenes.

PubMed

Wright, Michael J

2005-01-01

It has been proposed that the visual system encodes the salience of objects in the visual field in an explicit two-dimensional map that guides visual selective attention. Experiments were conducted to determine whether salience measurements applied to regions of pictures of outdoor scenes could predict the detection of changes in those regions. To obtain a quantitative measure of change detection, observers located changes in pairs of colour pictures presented across an interstimulus interval (ISI). Salience measurements were then obtained from different observers for image change regions using three independent methods, and all were positively correlated with change detection. Factor analysis extracted a single saliency factor that accounted for 62% of the variance contained in the four measures. Finally, estimates of the magnitude of the image change in each picture pair were obtained, using nine separate visual filters representing low-level vision features (luminance, colour, spatial frequency, orientation, edge density). None of the feature outputs was significantly associated with change detection or saliency. On the other hand it was shown that high-level (structural) properties of the changed region were related to saliency and to change detection: objects were more salient than shadows and more detectable when changed.

Effects of colour on preview search: anticipatory and inhibitory biases for colour.

PubMed

Braithwaite, Jason J; Humphreys, Glyn W; Hodsoll, John

2004-01-01

Two experiments are reported examining the effects of colour grouping, colour change and target colour foreknowledge under preview search conditions (Watson and Humphreys, 1997). In Experiment 1 we manipulated the colour homogeneity of the old items at initial presentation, and the colour these items subsequently changed into. In all cases participants knew the colour of the target. We found that when the old items changed into the same colour as the new search set, search performance was affected. In Experiment 2 participants did not know the colour of the target. Here we found evidence for a negative colour-based carry-over effect that slowed search for new targets carrying the colour of the old items. This occurred even when the old items changed their original colour and the new target was a singleton. Collectively the results suggest an important role for both colour grouping and colour-based inhibition in the successful rejection of old distractors. The consequence of this, however, is that new stimuli that may carry the critical attribute may take longer to detect. We discuss the results in relation to prior 'feature-blind' accounts of preview effects on visual search.

II Zw 40 - 30 Doradus on Steroids

NASA Astrophysics Data System (ADS)

Leitherer, Claus; Lee, Janice C.; Levesque, Emily M.

2017-11-01

We obtained HST COS G140L spectra of the enigmatic nearby blue compact dwarf galaxy II Zw 40. The galaxy hosts a nuclear super star cluster embedded in a radio-bright nebula, similar to those observed in the related blue compact dwarfs NGC 5253 and Henize 2-10. The ultraviolet spectrum of II Zw 40 is exceptional in terms of the strength of He II 1640, O III] 1666 and C III] 1909. We determined reddening, age, and the cluster mass from the ultraviolet data. The super nebula and the ionizing cluster exceed the ionizing luminosity and stellar mass of the local benchmark 30 Doradus by an order of magnitude. Comparison with stellar evolution models accounting for rotation reveals serious short-comings: these models do not account for the presence of Wolf-Rayet-like stars at young ages observed in II Zw 40. Photoionization modeling is used to probe the origin of the nebular lines and determine gas phase abundances. C/O is solar, in agreement with the result of the stellar-wind modeling.

Interband Tunneling for Hole Injection in III-Nitride Ultraviolet Emitters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuewei; Krishnamoorthy, Sriram; Johnson, Jared M.

Low p-type conductivity and high contact resistance remain a critical problem in wide band gap AlGaN-based ultraviolet light emitters due to the high acceptor ionization energy. In this work, interband tunneling is demonstrated for non-equilibrium injection of holes through the use of ultra-thin polarization-engineered layers that enhance tunneling probability by several orders of magnitude over a PN homojunction. Al 0.3Ga 0.7N interband tunnel junctions with a lowresistance of 5.6 × 10 -4 Ω cm 2 were obtained and integrated on ultraviolet light emitting diodes.Tunnel injection of holes was used to realize GaN-free ultraviolet light emitters with bottom and top n-typemore » Al 0.3Ga 0.7N contacts. At an emission wavelength of 327 nm, stable output power of 6 W/cm 2 at a current density of 120 A/cm 2 with a forward voltage of 5.9 V was achieved. Our demonstration of efficient interband tunneling could enable device designs for higher efficiency ultraviolet emitters.« less

VizieR Online Data Catalog: Faint blue objects at high galactic latitude (Mitchell+, 2004)

NASA Astrophysics Data System (ADS)

Mitchell, K. J.; Usher, P. D.

2006-11-01

The US (UV-excess Starlike) survey has cataloged 3987 objects in 7 high Galactic latitude fields according to their optical colors, magnitudes, and morphologies using photographic techniques. This paper analyzes the effectiveness of the survey at producing finding lists for complete samples of hot stars and quasars that exhibit blue and/or ultraviolet excess (B-UVX) relative to the colors of halo F and G subdwarf stars. A table of 599 spectroscopic identifications summarizes the spectroscopic coverage of the US objects that has been accomplished to date. (6 data files).

Item-method directed forgetting: Effects at retrieval?

PubMed

Taylor, Tracy L; Cutmore, Laura; Pries, Lotta

2018-02-01

In an item-method directed forgetting paradigm, words are presented one at a time, each followed by an instruction to Remember or Forget; a directed forgetting effect is measured as better subsequent memory for Remember words than Forget words. The dominant view is that the directed forgetting effect arises during encoding due to selective rehearsal of Remember over Forget items. In three experiments we attempted to falsify a strong view that directed forgetting effects in recognition are due only to encoding mechanisms when an item method is used. Across 3 experiments we tested for retrieval-based processes by colour-coding the recognition test items. Black colour provided no information; green colour cued a potential Remember item; and, red colour cued a potential Forget item. Recognition cues were mixed within-blocks in Experiment 1 and between-blocks in Experiments 2 and 3; Experiment 3 added explicit feedback on the accuracy of the recognition decision. Although overall recognition improved with cuing when explicit test performance feedback was added in Experiment 3, in no case was the magnitude of the directed forgetting effect influenced by recognition cueing. Our results argue against a role for retrieval-based strategies that limit recognition of Forget items at test and posit a role for encoding intentions only. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthetic IRIS spectra of the solar transition region: Effect of high-energy tails

NASA Astrophysics Data System (ADS)

Dzifčáková, E.; Vocks, C.; Dudík, J.

2017-06-01

Aims: The solar transition region satisfies the conditions for presence of non-Maxwellian electron energy distributions with high-energy tails at energies corresponding to the ionization potentials of many ions emitting in the extreme-ultraviolet and ultraviolet portions of the spectrum. Methods: We calculate the synthetic Si iv, O iv, and S iv spectra in the far ultraviolet channel of the Interface Region Imaging Spectrograph (IRIS). Ionization, recombination, and excitation rates are obtained by integration of the cross-sections or their approximations over the model electron distributions considering particle propagation from the hotter corona. Results: The ionization rates are significantly affected by the presence of high-energy tails. This leads to the peaks of the relative abundance of individual ions to be broadened with pronounced low-temperature shoulders. As a result, the contribution functions of individual lines observable by IRIS also exhibit low-temperature shoulders, or their peaks are shifted to temperatures an order of magnitude lower than for the Maxwellian distribution. The integrated emergent spectra can show enhancements of Si iv compared to O iv by more than a factor of two. Conclusions: The high-energy particles can have significant impact on the emergent spectra and their presence needs to be considered even in situations without strong local acceleration.

Development of vacuum ultraviolet absorption spectroscopy system for wide measurement range of number density using a dual-tube inductively coupled plasma light source

NASA Astrophysics Data System (ADS)

Kuwahara, Akira; Matsui, Makoto; Yamagiwa, Yoshiki

2012-12-01

A vacuum ultraviolet absorption spectroscopy system for a wide measurement range of atomic number densities is developed. Dual-tube inductively coupled plasma was used as a light source. The probe beam profile was optimized for the target number density range by changing the mass flow rate of the inner and outer tubes. This system was verified using cold xenon gas. As a result, the measurement number density range was extended from the conventional two orders to five orders of magnitude.

Experimental observation of attosecond control over relativistic electron bunches with two-colour fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeung, M.; Rykovanov, S.; Bierbach, J.

2016-12-05

Energy coupling during relativistically intense laser–matter interactions is encoded in the attosecond motion of strongly driven electrons at the pre-formed plasma–vacuum boundary. Studying and controlling this motion can reveal details about the microscopic processes that govern a vast array of light–matter interaction phenomena, including those at the forefront of extreme laser–plasma science such as laser-driven ion acceleration, bright attosecond pulse generation and efficient energy coupling for the generation and study of warm dense matter. Here in this paper, we experimentally demonstrate that by precisely adjusting the relative phase of an additional laser beam operating at the second harmonic of themore » driving laser it is possible to control the trajectories of relativistic electron bunches formed during the interaction with a solid target at the attosecond scale. Finally, we observe significant enhancements in the resulting high-harmonic yield, suggesting potential applications for sources of ultra-bright, extreme ultraviolet attosecond radiation to be used in atomic and molecular pump–probe experiments« less

Far Ultraviolet Spectroscopic Explorer Spectroscopy of the Nova-Like Cataclysmic Variable BB Doradus

DTIC Science & Technology

2008-06-27

which we have best-fit models in the parameter space, we use the infrared magnitudes J, H, and K from the Two Micron All Sky Survey ( 2MASS ) to assess the...in a high state with a visual red magnitude R ¼ 14:60 and a blue magnitude B ¼ 13:90 (whereas B 16:5 in the low state). The 2MASS IR apparent...therefore certainly larger than 300 pc, and most likely in the range of 500 pc. Since BB Dor was observed in a high state (with 2MASS ), it is likely

Best not to bet on the horserace: A comment on Forrin and MacLeod (2017) and a relevant stimulus-response compatibility view of colour-word contingency learning asymmetries.

PubMed

Schmidt, James R

2018-02-01

One powerfully robust method for the study of human contingency learning is the colour-word contingency learning paradigm. In this task, participants respond to the print colour of neutral words, each of which is presented most often in one colour. The contingencies between words and colours are learned, as indicated by faster and more accurate responses when words are presented in their expected colour relative to an unexpected colour. In a recent report, Forrin and MacLeod (2017b, Memory & Cognition) asked to what extent this performance (i.e., response time) measure of learning might depend on the relative speed of processing of the word and the colour. With keypress responses, learning effects were comparable when responding to the word and to the colour (contrary to predictions). However, an asymmetry appeared in a second experiment with vocal responses, with a contingency effect only present for colour identification. In a third experiment, the colour was preexposed, and contingency effects were again roughly symmetrical. In their report, they suggested that a simple speed-of-processing (or "horserace") model might explain when contingency effects are observed in colour and word identification. In the present report, an alternative view is presented. In particular, it is argued that the results are best explained by appealing to the notion of relevant stimulus-response compatibility, which also resolves discrepancies between horserace model predictions and participant results. The article presents simulations with the Parallel Episodic Processing model to demonstrate this case.

Characterizing the WISE-selected heavily obscured quasar population with optical spectroscopy from the Southern African Large Telescope

NASA Astrophysics Data System (ADS)

Hviding, Raphael E.; Hickox, Ryan C.; Hainline, Kevin N.; Carroll, Christopher M.; DiPompeo, Michael A.; Yan, Wei; Jones, Mackenzie L.

2018-02-01

We present the results of an optical spectroscopic survey of 46 heavily obscured quasar candidates. Objects are selected using their mid-infrared (mid-IR) colours and magnitudes from the Wide-Field Infrared Survey Explorer (WISE) anzd their optical magnitudes from the Sloan Digital Sky Survey. Candidate Active Galactic Nuclei (AGNs) are selected to have mid-IR colours indicative of quasar activity and lie in a region of mid-IR colour space outside previously published X-ray based selection regions. We obtain optical spectra for our sample using the Robert Stobie Spectrograph on the Southern African Large Telescope. 30 objects (65 per cent) have identifiable emission lines, allowing for the determination of spectroscopic redshifts. Other than one object at z ˜ 2.6, candidates have moderate redshifts ranging from z = 0.1 to 0.8 with a median of 0.3. 21 (70 per cent) of our objects with identified redshift (46 per cent of the whole sample) are identified as AGNs through common optical diagnostics. We model the spectral energy distributions of our sample and found that all require a strong AGN component, with an average intrinsic AGN fraction at 8 μm of 0.91. Additionally, the fits require large extinction coefficients with an average E(B - V)AGN = 17.8 (average A(V)AGN = 53.4). By focusing on the area outside traditional mid-IR photometric cuts, we are able to capture and characterize a population of deeply buried quasars that were previously unattainable through X-ray surveys alone.

Trial type mixing substantially reduces the response set effect in the Stroop task.

PubMed

Hasshim, Nabil; Parris, Benjamin A

2017-03-20

The response set effect refers to the finding that an irrelevant incongruent colour-word produces greater interference when it is one of the response options (referred to as a response set trial), compared to when it is not (a non-response set trial). Despite being a key effect for models of selective attention, the magnitude of the effect varies considerably across studies. We report two within-subjects experiments that tested the hypothesis that presentation format modulates the magnitude of the response set effect. Trial types (e.g. response set, non-response set, neutral) were either presented in separate blocks (pure) or in blocks containing trials from all conditions presented randomly (mixed). In the first experiment we show that the response set effect is substantially reduced in the mixed block context as a result of a decrease in RTs to response set trials. By demonstrating the modulation of the response set effect under conditions of trial type mixing we present evidence that is difficult for models of the effect based on strategic, top-down biasing of attention to explain. In a second experiment we tested a stimulus-driven account of the response set effect by manipulating the number of colour-words that make up the non-response set of distractors. The results show that the greater the number of non-response set colour concepts, the smaller the response set effect. Alternative accounts of the data and its implications for research debating the automaticity of reading are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Preschoolers' Mathematical Play and Colour Preferences: A New Window into the Development of Gendered Beliefs about Math

ERIC Educational Resources Information Center

Paz-Albo Prieto, Jesús; Cvencek, Dario; Herranz Llácer, Cristina V.; Hervás Escobar, Aránzazu; Meltzoff, Andrew N.

2017-01-01

In play, children often explore mathematical ideas that are vital for future learning. Children's play also reveals gender differences in both colour and toy preferences. The authors examined how gender-related colour preferences of 5-year-olds are related to preferences for math-specific games/toys and gendered beliefs about math. Spanish…

The Carnegie Chicago Hubble Program: The Mid-Infrared Colours of Cepheids and the Effect of Metallicity on the CO Band-Head at 4.6 Micron

NASA Technical Reports Server (NTRS)

Scowcroft, Victoria; Seibert, Mark; Freedman, Wendy L.; Beaton, Rachael L.; Madore, Barry F.; Monson, Andrew J.; Rich, Jeffery A.; Rigby, Jane R.

2016-01-01

We compare mid-infrared (IR) 3.6 and 4.5 micron Warm Spitzer observations for Cepheids in the Milky Way and the Large and Small Magellanic Clouds. Using models, we explore in detail the effect of the CO rotation-vibration band-head at 4.6 micron on the mid-IR photometry. We confirm the temperature sensitivity of the CO band-head at 4.6 micron and find no evidence for an effect at 3.6 micron. We compare the ([3.6]-[4.5]) period-colour relations in the MW, LMC and SMC. The slopes of the period-colour relations for the three galaxies are in good agreement, but there is a trend in zero-point with metallicity, with the lowest metallicity Cepheids having redder mid-IR colours. Finally, we present a colour-[Fe/H] relation based on published spectroscopic metallicities. This empirical relation, calibrated to the metallicity system of Genovali et al., demonstrates that the ([3.6]-[4.5]) colour provides a reliable metallicity indicator for Cepheids, with a precision comparable to current spectroscopic determinations.

Classifying Natural Waters with the Forel-Ule Colour Index System: Results, Applications, Correlations and Crowdsourcing.

PubMed

Garaba, Shungudzemwoyo P; Friedrichs, Anna; Voß, Daniela; Zielinski, Oliver

2015-12-18

Societal awareness of changes in the environment and climate has grown rapidly, and there is a need to engage citizens in gathering relevant scientific information to monitor environmental changes due to recognition that citizens are a potential source of critical information. The apparent colour of natural waters is one aspect of our aquatic environment that is easy to detect and an essential complementary optical water quality indicator. Here we present the results and explore the utility of the Forel-Ule colour index (FUI) scale as a proxy for different properties of natural waters. A FUI scale is used to distinguish the apparent colours of different natural surface water masses. Correlation analysis was completed in an effort to determine the constituents of natural waters related to FUI. Strong correlations with turbidity, Secchi-disk depth, and coloured dissolved organic material suggest the FUI is a good indicator of changes related to other constituents of water. The increase in the number of tools capable of determining the FUI colours, (i) ocean colour remote sensing products; (ii) a handheld scale; and (iii) a mobile device app, make it a versatile relative measure of water quality. It has the potential to provide higher spatial and temporal resolution of data for a modernized classification of optical water quality. This FUI colour system has been favoured by several scientists in the last century because it is affordable and easy to use and provides indicative information about the colour of water and the water constituents producing that colour. It is therefore within the scope of a growing interest in the application and usefulness of basic measurement methodologies with the potential to provide timely benchmark information about the environment to the public, scientists and policymakers.

Classifying Natural Waters with the Forel-Ule Colour Index System: Results, Applications, Correlations and Crowdsourcing

PubMed Central

Garaba, Shungudzemwoyo P.; Friedrichs, Anna; Voß, Daniela; Zielinski, Oliver

2015-01-01

Societal awareness of changes in the environment and climate has grown rapidly, and there is a need to engage citizens in gathering relevant scientific information to monitor environmental changes due to recognition that citizens are a potential source of critical information. The apparent colour of natural waters is one aspect of our aquatic environment that is easy to detect and an essential complementary optical water quality indicator. Here we present the results and explore the utility of the Forel-Ule colour index (FUI) scale as a proxy for different properties of natural waters. A FUI scale is used to distinguish the apparent colours of different natural surface water masses. Correlation analysis was completed in an effort to determine the constituents of natural waters related to FUI. Strong correlations with turbidity, Secchi-disk depth, and coloured dissolved organic material suggest the FUI is a good indicator of changes related to other constituents of water. The increase in the number of tools capable of determining the FUI colours, (i) ocean colour remote sensing products; (ii) a handheld scale; and (iii) a mobile device app, make it a versatile relative measure of water quality. It has the potential to provide higher spatial and temporal resolution of data for a modernized classification of optical water quality. This FUI colour system has been favoured by several scientists in the last century because it is affordable and easy to use and provides indicative information about the colour of water and the water constituents producing that colour. It is therefore within the scope of a growing interest in the application and usefulness of basic measurement methodologies with the potential to provide timely benchmark information about the environment to the public, scientists and policymakers. PMID:26694444

Plumage brightness as an indicator of parental care in northern cardinals

PubMed

Linville; Breitwisch; Schilling

1998-01-01

Good parent and differential allocation models predict relationships between degree of sexual ornamentation and parental care, but relatively few studies have tested these models. The northern cardinal, Cardinalis cardinalis, is a sexually dichromatic species in which both sexes are ornamented. Males have red plumage, and females have tan plumage with limited areas of red feathering. Cardinals were used to address the two models and determine whether plumage brightness signals level of parental care by both sexes. Absolute effort in feeding nestlings by males was not correlated with male breast plumage colour, but effort by females was positively correlated with female underwing plumage colour. Absolute feeding effort by females was also inversely related to brightness of the mate's breast colour. As a consequence, the proportion of a pair's total feedings provided by the male was positively correlated with male breast colour. Proportion of total feedings provided by the female was positively correlated with female wing colour. Feeding efforts (both per nest and per nestling) were correlated between mates, but birds did not mate assortatively in relation to colour. These results support the good parent hypothesis, suggesting colour brightness is a signal of parental care. The results also indicate that ornamentation of both members of the pair may be important determinants of relative efforts in provisioning nestlings by parent birds. Copyright 1998 The Association for the Study of Animal Behaviour.

The natural moon illusion: a multifactor angular account.

PubMed

Plug, C; Ross, H E

1994-01-01

It is argued that the failure to explain the celestial illusion results from conceptual confusion about perceived size and from disregard of the observational evidence relating to the natural moon illusion. The evidence shows that the illusion consists of a perceived angular size enlargement of horizon objects, by a factor of about 1.5-2.0 in diameter in comparison with elevated objects. Most measurements of the illusion have been made in terms of angular size, although in some proposed explanations an illusion of linear size is assumed. The magnitude of the illusion varies, particularly with the detail of the horizon scene. The illusion can be explained as the sum of several factors that affect perceived angular size: size contrast, vergence commands and eye or head position, aerial perspective, and colour. The relative contributions of these factors are assessed.

Colours’ Impact on Morality: Evidence from Event-related Potentials

PubMed Central

Gan, Tian; Fang, Wei; Ge, Liezhong

2016-01-01

Black and white have been shown to be representations of moral concepts. The purpose of this study was to investigate whether colours other than black and white have similar effects on words related to morality and to determine the time course of these effects. We presented moral and immoral words in three colours (red, green and blue) in a Moral Stroop task and used the event-related potential (ERP) technique to identify the temporal dynamics of the impact of colours on moral judgement. The behavioural results showed that it took longer for people to judge immoral words than moral words when the words were coloured green than when they were red or blue. The ERP results revealed the time course of these effects. Three stages were identified in the significant effects of P200, N300 and LPC. These findings suggest a metaphorical association between the colour green and moral information. PMID:28004749

Predicting stellar angular diameters from V, IC, H and K photometry

NASA Astrophysics Data System (ADS)

Adams, Arthur D.; Boyajian, Tabetha S.; von Braun, Kaspar

2018-01-01

Determining the physical properties of microlensing events depends on having accurate angular sizes of the source star. Using long baseline optical interferometry, we are able to measure the angular sizes of nearby stars with uncertainties ≤2 per cent. We present empirically derived relations of angular diameters which are calibrated using both a sample of dwarfs/subgiants and a sample of giant stars. These relations are functions of five colour indices in the visible and near-infrared, and have uncertainties of 1.8-6.5 per cent depending on the colour used. We find that a combined sample of both main-sequence and evolved stars of A-K spectral types is well fitted by a single relation for each colour considered. We find that in the colours considered, metallicity does not play a statistically significant role in predicting stellar size, leading to a means of predicting observed sizes of stars from colour alone.

The time course of activation of object shape and shape+colour representations during memory retrieval.

PubMed

Lloyd-Jones, Toby J; Roberts, Mark V; Leek, E Charles; Fouquet, Nathalie C; Truchanowicz, Ewa G

2012-01-01

Little is known about the timing of activating memory for objects and their associated perceptual properties, such as colour, and yet this is important for theories of human cognition. We investigated the time course associated with early cognitive processes related to the activation of object shape and object shape+colour representations respectively, during memory retrieval as assessed by repetition priming in an event-related potential (ERP) study. The main findings were as follows: (1) we identified a unique early modulation of mean ERP amplitude during the N1 that was associated with the activation of object shape independently of colour; (2) we also found a subsequent early P2 modulation of mean amplitude over the same electrode clusters associated with the activation of object shape+colour representations; (3) these findings were apparent across both familiar (i.e., correctly coloured - yellow banana) and novel (i.e., incorrectly coloured - blue strawberry) objects; and (4) neither of the modulations of mean ERP amplitude were evident during the P3. Together the findings delineate the timing of object shape and colour memory systems and support the notion that perceptual representations of object shape mediate the retrieval of temporary shape+colour representations for familiar and novel objects.

The Time Course of Activation of Object Shape and Shape+Colour Representations during Memory Retrieval

PubMed Central

Lloyd-Jones, Toby J.; Roberts, Mark V.; Leek, E. Charles; Fouquet, Nathalie C.; Truchanowicz, Ewa G.

2012-01-01

Little is known about the timing of activating memory for objects and their associated perceptual properties, such as colour, and yet this is important for theories of human cognition. We investigated the time course associated with early cognitive processes related to the activation of object shape and object shape+colour representations respectively, during memory retrieval as assessed by repetition priming in an event-related potential (ERP) study. The main findings were as follows: (1) we identified a unique early modulation of mean ERP amplitude during the N1 that was associated with the activation of object shape independently of colour; (2) we also found a subsequent early P2 modulation of mean amplitude over the same electrode clusters associated with the activation of object shape+colour representations; (3) these findings were apparent across both familiar (i.e., correctly coloured – yellow banana) and novel (i.e., incorrectly coloured - blue strawberry) objects; and (4) neither of the modulations of mean ERP amplitude were evident during the P3. Together the findings delineate the timing of object shape and colour memory systems and support the notion that perceptual representations of object shape mediate the retrieval of temporary shape+colour representations for familiar and novel objects. PMID:23155393

Investigating broad absorption line quasars with SDSS and UKIDSS .

NASA Astrophysics Data System (ADS)

Maddox, Natasha; Hewett, P. C.

The SDSS contains the largest set of spectroscopically confirmed broad line quasars ever compiled. Upon its completion, the UKIDSS LAS will provide a near-infrared counterpart to the SDSS, reaching 3 magnitudes deeper than 2MASS over a 4000 square degree area within the SDSS footprint. Combining the SDSS optical and UKIDSS near-infrared data, allows a new insight into the photometric and spectroscopic properties of broad absorption line quasars (BALQSOs) relative to the quasar population as a whole. An accurate estimate of the intrinsic BALQSO fraction is essential for determining the BAL cloud covering fraction and the implications for the co-evolution of accreting supermassive black holes and their host galaxies. Defining a K-band limited sample of quasars makes clear the significantly redder distribution of i-K colours of the BALQSOs. The BALQSO i-K colour distribution enables us to estimate a lower limit to the intrinsic BALQSO fraction, computed to be ˜ 30 percent, significantly larger than the optical fraction of 15-20 percent found by several authors. We combined the high-quality SDSS spectra of the quasar sample to make several composite spectra based on i-K colour, and the properties of these composites are compared to a composite spectrum of unreddened quasars. If the origin of the wavelength dependent differences between the red and unreddened objects is ascribed to attenuation by dust, we find that the extinction curve of the material is intermediate in form between the steep SMC-like extinction curve and the recent, empirically determined, extinction curve presented by Gaskell & Benker (2007).

Shaping communicative colour signals over evolutionary time

PubMed Central

Oyola Morales, José R.; Vital-García, Cuauhcihuatl; Hews, Diana K.; Martins, Emília P.

2016-01-01

Many evolutionary forces can shape the evolution of communicative signals, and the long-term impact of each force may depend on relative timing and magnitude. We use a phylogenetic analysis to infer the history of blue belly patches of Sceloporus lizards, and a detailed spectrophotometric analysis of four species to explore the specific forces shaping evolutionary change. We find that the ancestor of Sceloporus had blue patches. We then focus on four species; the first evolutionary shift (captured by comparison of S. merriami and S. siniferus) represents an ancient loss of the belly patch by S. siniferus, and the second evolutionary shift, bounded by S. undulatus and S. virgatus, represents a more recent loss of blue belly patch by S. virgatus. Conspicuousness measurements suggest that the species with the recent loss (S. virgatus) is the least conspicuous. Results for two other species (S. siniferus and S. merriami) suggest that over longer periods of evolutionary time, new signal colours have arisen which minimize absolute contrast with the habitat while maximizing conspicuousness to a lizard receiver. Specifically, males of the species representing an ancient loss of blue patch (S. siniferus) are more conspicuous than are females in the UV, whereas S. merriami males have evolved a green element that makes their belly patches highly sexually dimorphic but no more conspicuous than the white bellies of S. merriami females. Thus, our results suggest that natural selection may act more immediately to reduce conspicuousness, whereas sexual selection may have a more complex impact on communicative signals through the introduction of new colours. PMID:28018661

Shaping communicative colour signals over evolutionary time.

PubMed

Ossip-Drahos, Alison G; Oyola Morales, José R; Vital-García, Cuauhcihuatl; Zúñiga-Vega, J Jaime; Hews, Diana K; Martins, Emília P

2016-11-01

Many evolutionary forces can shape the evolution of communicative signals, and the long-term impact of each force may depend on relative timing and magnitude. We use a phylogenetic analysis to infer the history of blue belly patches of Sceloporus lizards, and a detailed spectrophotometric analysis of four species to explore the specific forces shaping evolutionary change. We find that the ancestor of Sceloporus had blue patches. We then focus on four species; the first evolutionary shift (captured by comparison of S. merriami and S. siniferus ) represents an ancient loss of the belly patch by S. siniferus , and the second evolutionary shift, bounded by S. undulatus and S. virgatus , represents a more recent loss of blue belly patch by S. virgatus . Conspicuousness measurements suggest that the species with the recent loss ( S. virgatus ) is the least conspicuous. Results for two other species ( S. siniferus and S. merriami ) suggest that over longer periods of evolutionary time, new signal colours have arisen which minimize absolute contrast with the habitat while maximizing conspicuousness to a lizard receiver. Specifically, males of the species representing an ancient loss of blue patch ( S. siniferus ) are more conspicuous than are females in the UV, whereas S. merriami males have evolved a green element that makes their belly patches highly sexually dimorphic but no more conspicuous than the white bellies of S. merriami females. Thus, our results suggest that natural selection may act more immediately to reduce conspicuousness, whereas sexual selection may have a more complex impact on communicative signals through the introduction of new colours.

Colour in flux: describing and printing colour in art

NASA Astrophysics Data System (ADS)

Parraman, Carinna

2008-01-01

This presentation will describe artists, practitioners and scientists, who were interested in developing a deeper psychological, emotional and practical understanding of the human visual system who were working with wavelength, paint and other materials. From a selection of prints at The Prints and Drawings Department at Tate London, the presentation will refer to artists who were motivated by issues relating to how colour pigment was mixed and printed, to interrogate and explain colour perception and colour science, and in art, how artists have used colour to challenge the viewer and how a viewer might describe their experience of colour. The title Colour in Flux refers, not only to the perceptual effect of the juxtaposition of one colour pigment with another, but also to the changes and challenges for the print industry. In the light of screenprinted examples from the 60s and 70s, the presentation will discuss 21 st century ideas on colour and how these notions have informed the Centre for Fine Print Research's (CFPR) practical research in colour printing. The latter part of this presentation will discuss the implications for the need to change methods in mixing inks that moves away from existing colour spaces, from non intuitive colour mixing to bespoke ink sets, colour mixing approaches and colour mixing methods that are not reliant on RGB or CMYK.

Characterizing mid-ultraviolet to optical light curves of nearby type IIn supernovae

DOE PAGES

de la Rosa, Janie; Roming, Pete; Pritchard, Tyler; ...

2016-03-21

Here, we present early mid-ultraviolet and optical observations of Type IIn supernovae (SNe IIn) observed from 2007 to 2013. Our results focus on the properties of UV light curves: peak absolute magnitudes, temporal decay, and color evolution. During early times, this sample demonstrates that UV light decays faster than optical, and each event transitions from a predominantly UV-bright phase to an optically bright phase. In order to understand early UV behavior, we generate and analyze the sample's blackbody luminosity, temperature, and radius as the SN ejecta expand and cool. Since most of our observations were detected post maximum luminosity, wemore » introduce a method for estimating the date of peak magnitude. When our observations are compared based on filter, we find that even though these SNe IIn vary in peak magnitudes, there are similarities in UV decay rates. We use a simple semi-analytical SN model in order to understand the effects of the explosion environment on our UV observations. Understanding the UV characteristics of nearby SNe IIn during an early phase can provide valuable information about the environment surrounding these explosions, leading us to evaluating the diversity of observational properties in this subclass.« less

Measurements and modelling of the influence of dentine colour and enamel on tooth colour.

PubMed

Battersby, Paul D; Battersby, Stephen J

2015-03-01

We provide a quantitative predictive model for the extent to which coloured dentine, visible through the enamel, contributes to tooth colour. Our model uses (L(*),a(*),b(*)) measurements rather than spectral measurements. We have used a model system, composed of a slice of bovine enamel placed on top of coloured paper. We have measured the colour of the enamel-paper combination, as an analogue for a tooth, and have related this to the colour of the paper, as an analogue for dentine. By changing the paper colour, we have been able to explore how the colour of dentine determines tooth colour, according to our model system. We have also compared hydrated and desiccated samples. In qualitative terms, superimposing the enamel on top of the paper increases the "lightness" for all colours tested except white while simultaneously reducing the chromaticity, a measure of the extent to which the colour differs from grey. Desiccated enamel is much more effective at increasing the lightness and reducing the chromaticity than hydrated enamel. Quantitatively, our measurements are reproduced by the mathematical model we have developed to within 2% in "lightness" and about 8% in chromaticity. We are able to predict the colour of an analogue for a tooth, composed of bovine enamel and coloured paper, from the colour of an analogue for the dentine, the coloured paper alone, with good accuracy. This understanding provides insights into the role of dentine colour in determining tooth colour. Our work helps quantify the importance of dentine colour, compared to other, extrinsic causes of colour, such as staining, in determining the visible colour of teeth. Our predicted colours represent a baseline to which extrinsic sources will add. Copyright © 2015. Published by Elsevier Ltd.

An RGB approach to prismatic colours

NASA Astrophysics Data System (ADS)

Theilmann, Florian; Grusche, Sascha

2013-11-01

Teaching prismatic colours usually boils down to establishing the take-home message that white light consists of ‘differently refrangible’ coloured rays. This approach explains the classical spectrum of seven colours but has its limitations, e.g. in discussing spectra from setups with higher resolution or in understanding the well saturated colours of simple edge spectra. Besides, the connection of physical wavelength and colour remains obscure—after all, colour and wavelength are not equivalent. In this paper, we suggest that teachers demonstrate these impressive experiments in the classroom by using a video projector and a prism to disperse black-and-white slit images. We introduce experimental and diagrammatic methods for establishing the connection between the original slit image and the wavelength composition of the resulting spectrum. From this (or any other given) wavelength composition, students can systematically derive the colours with a simple RGB approach, thus gaining a more accurate picture of the relation between wavelength and colour.

Galaxy clusters in the cosmic web

NASA Astrophysics Data System (ADS)

Acebrón, A.; Durret, F.; Martinet, N.; Adami, C.; Guennou, L.

2014-12-01

Simulations of large scale structure formation in the universe predict that matter is essentially distributed along filaments at the intersection of which lie galaxy clusters. We have analysed 9 clusters in the redshift range 0.4

Blue-yellow colour vision impairment and cognitive deficits in occasional and dependent stimulant users.

PubMed

Hulka, Lea M; Wagner, Michael; Preller, Katrin H; Jenni, Daniela; Quednow, Boris B

2013-04-01

Specific blue-yellow colour vision impairment has been reported in dependent cocaine users and it was postulated that drug-induced changes in retinal dopamine neurotransmission are responsible. However, it is unclear whether these changes are confined to chronic cocaine users, whether they are specific for dopaminergic stimulants such as cocaine and amphetamine and whether they are related to cognitive functions such as working memory, encoding and consolidation. In 47 occasional and 29 dependent cocaine users, 23 MDMA (commonly known as 'ecstasy') users and 47 stimulant-naive controls, colour vision discrimination was measured with the Lanthony Desaturated Panel D-15 Test and memory performance with the Auditory Verbal Learning Test. Both occasional and dependent cocaine users showed higher colour confusion indices than controls. Users of the serotonergic stimulant MDMA (26%), occasional (30%) and dependent cocaine users (34%) exhibited more frequent blue-yellow colour vision disorders compared to controls (9%). Inferior performance of MDMA users was caused by a subgroup with high amphetamine co-use (55%), while MDMA use alone was not associated with decreased blue-yellow discrimination (0%). Cognitive performance was worse in cocaine users with colour vision disorder compared to users and controls with intact colour vision and both colour vision impairment and cognitive deficits were related to cocaine use. Occasional cocaine and amphetamine use might induce blue-yellow colour vision impairment, whereas the serotonergic stimulant MDMA does not impair colour vision. The association between colour vision impairment and cognitive deficits in cocaine users may reflect that retinal and cerebral dopamine alterations are linked to a certain degree.

Stellar and planetary remnants in digital sky surveys

NASA Astrophysics Data System (ADS)

Girven, Jonathan

Large scale digital sky surveys have produced an unprecedented volume of uniform data covering both vast proportions of the sky and a wide range of wavelength, from the ultraviolet to the near-infrared. The challenge facing astronomers today is how to use this multitude of information to extract trends, outliers and and rare objects. For example, a large sample of single white dwarf stars has the potential to probe the Galaxy through the luminosity function. The aim of this work was to study stellar and planetary remnants in these surveys. In the last few decades, it has been shown that a handful of white dwarfs have remnants of planetary systems around them, in the form of a dusty disc. These are currently providing the best constraints on the composition of extra-solar planetary systems. Finding significant numbers of dusty discs is only possible in large scale digital sky surveys. I ultilised the SDSS DR7 and colour-colour diagrams to and DA white dwarfs from optical photometry. This nearly doubled the number of spectroscopically confirmed DA white dwarfs in the SDSS compared with DR4 [Eisenstein et al., 2006], and introduced nearly 10; 000 photometric-only DA white dwarf candidates. I further cross-matched our white dwarf catalogue with UKIDSS LAS DR8 to carry out the currently largest and deepest untargeted search for low-mass companions to, and dust discs around, DA white dwarfs. Simultaneously, I analyzed Spitzer observations of 15 white dwarfs with metal-polluted atmospheres, all but one having helium-dominated atmospheres. Three of these stars were found to have an infrared excess consistent with a dusty disc. I used the total sample to estimate a typical disc lifetime of log[tdisc(yr)] = 5:6+1:1, which is compatible with the relatively large range estimated from different theoretical models. Subdwarf population synthesis models predicted a vast population of subdwarfs with F to K-type companions, produced in the effcient RLOF formation channel. I used a cross-match of ultraviolet, optical and infrared surveys to search for this unseen population. I select a complementary sample to those found from radial velocity surveys, offering direct tests of binary evolution pathways. Finally, I present a method to use common proper motion white dwarf pairs to constrain the initial-final mass relation, which is extremely uncertain at low masses. In the example I show, one of the stars is a magnetic white dwarf with B ' 6 MG, making this a rare and intriguing system from a magnetic white dwarf formation point of view.

Investigating the impact of age-depended hair colour darkening during childhood on DNA-based hair colour prediction with the HIrisPlex system.

PubMed

Kukla-Bartoszek, Magdalena; Pośpiech, Ewelina; Spólnicka, Magdalena; Karłowska-Pik, Joanna; Strapagiel, Dominik; Żądzińska, Elżbieta; Rosset, Iwona; Sobalska-Kwapis, Marta; Słomka, Marcin; Walsh, Susan; Kayser, Manfred; Sitek, Aneta; Branicki, Wojciech

2018-06-06

Predictive DNA analysis of externally visible characteristics exerts an increasing influence on contemporary forensic and anthropological investigations, with pigmentation traits currently being the most advanced for predictive modelling. Since pigmentation prediction error in some cases may be due to the result of age-related hair colour darkening, and sex influence in eye colour, this study aims to investigate these less explored phenomena on a group of juvenile individuals. Pigmentation phenotypes of children between the age of 6-13 years old were evaluated, in addition to data about their hair colour during early childhood from a select number of these individuals. The HIrisPlex models for DNA-based eye and hair colour prediction were used with input from SNP genotyping using massive parallel sequencing. Analysis of the total group of 476 children showed high accuracy in blue (AUC = 0.89) and brown (AUC = 0.91) eye colour prediction, while hair colour was predicted with AUC = 0.64 for blond, AUC = 0.64 for brown and AUC = 0.97 for red. 70.8% (n = 143) of the total number of children phenotypically blond for hair colour during early childhood progressed to brown during advanced childhood. In 70.6% (n = 101) of those cases, an incorrect blond hair prediction was made during the time of analysis. A noticeable decline in AUC values for blond (from 0.76 to 0.65) and brown (from 0.72 to 0.64) were observed when comparing hair colour prediction outcomes for the phenotypes recorded for the two different time points (at the age of 2-3 and 6-13). The number of incorrect blond hair colour predictions was significantly higher in children with brown hair at age 6-13 who were blond at early childhood (n = 47, 32.9%), relative to children who had brown hair at both time points (n = 6, 9.4%). However, in 28.0% (n = 40) of children who did experience hair colour darkening, HIrisPlex provided the correct prediction for the darkened hair colour phenotype, despite them being blond in early childhood. Our study implies that HIrisPlex can correctly predict adult hair colour in some individuals who experience age-related hair colour darkening during adolescence. However, in most instances prediction seems to default to the pre-adolescent hair colour for individuals with this phenomenon. In the future, the full adolescent age range in which hair colour darkening can occur should be considered in the study samples used for training hair colour prediction models to obtain a more complete picture of the phenomenon and its impact on DNA-based hair colour prediction in adults. Copyright © 2018 Elsevier B.V. All rights reserved.

Mass-loss rates and luminosities of evolved stars in the Magellanic Clouds .

NASA Astrophysics Data System (ADS)

Groenewegen, M. A. T.; Sloan, G. C.

Stars on the asymptotic giant branch (AGB) stars play an important role in the chemical evolution of their host galaxies and the life cycle of dust in the interstellar medium. A detailed and quantitative understanding of they lose mass and eject their envelopes remains elusive, particularly how that process depends on metallicity. Groenewegen & Sloan (2017, hereafter GS17) recently presented dust radiative transfer models for 225 carbon stars and 171 oxygen-rich evolved stars in the Magellanic Clouds and four nearby dSphs which were observed with the Infrared spectrograph on the Spitzer Space Telescope. They applied a minimisation procedure to fit models to spectral energy distributions constructed from the infrared spectra and the available optical and infrared photometry for each star to determine its luminosity and dust mass-loss rate (MLR). In this contribution two items from that paper are highlighted: an update on MSX SMC 055, which Groenewegen et al. (2009) suggested could be a super-AGB star, and a discussion of synthetic colour-colour and colour-magnitude diagrams expected from the James Webb Space Telescope.

Colour measurements of surfaces to evaluate the restoration materials

NASA Astrophysics Data System (ADS)

Lo Monaco, Angela; Marabelli, Maurizio; Pelosi, Claudia; Picchio, Rodolfo

2011-06-01

In this paper two case studies on the application of colour measurements for the evaluation of some restoration materials are discussed. The materials related to the research are: watercolours employed in restoration of wall paintings and preservative/consolidants for wood artifacts. Commercial watercolours, supplied by Maimeri, Windsor&Newton and Talens factories have been tested. Colour measurements have been performed by means of a reflectance spectrophotometer (RS) before and after accelerated ageing of watercolours at 92% relative humidity (RH) and in a Solar Box chamber. The experimental results show that watercolours based on natural earths and artificial ultramarine undergo the main colour changes, expressed as L*, a* and b* variations and total colour difference (▵E*). In the other cases colour differences depend on both watercolour typology and suppliers. The other example concerns the evaluation of colour change due to surface treatment of Poplar (Populus sp.) and chestnut (Castanea sativa L.) wood samples. The wooden samples have been treated with a novel organic preservative/consolidant product that has been tested also in a real case as comparison. The treated samples have been artificially aged in Solar Box chamber equipped with a 280 nm UV filter. Colour has been measured before and after the artificial ageing by means of a RS. Colour changes have been determined also for the main door of an historical mansion in Viterbo, made of chestnut wood, and exposed outdoors.

VI photometry of the galactic cluster Berkeley 66

NASA Astrophysics Data System (ADS)

Guarnieri, M. D.; Carraro, G.

1997-03-01

A colour magnitude diagram (CMD) extending to V ~= 19 mag is given for 444 stars in the region of the galactic cluster Berkeley 66. The V and I photometry of a nearby field is also reported. This object appears very faint, highly contaminated by foreground stars and very reddened. The apparent distance modulus (m-M) and the colour excess E_{V-I} are guessed to be 17.5 and 1.1, respectively, with an uncertainty of at least 30%. Adopting these values the comparison of the CMD with theoretical isochrones from the Padova group provides an age around 1.0 Gyr. Based on observations carried out at Pino Torinese Observatory, Torino, Italy. Table 2 is available only in electronic form at the CDS via anonymous ftp 130.79.128.5.

Smoke optical depths - Magnitude, variability, and wavelength dependence

NASA Technical Reports Server (NTRS)

Pueschel, R. F.; Russell, P. B.; Colburn, D. A.; Ackerman, T. P.; Allen, D. A.

1988-01-01

An airborne autotracking sun-photometer has been used to measure magnitudes, temporal/spatial variabilities, and the wavelength dependence of optical depths in the near-ultraviolet to near-infrared spectrum of smoke from two forest fires and one jet fuel fire and of background air. Jet fuel smoke optical depths were found to be generally less wavelength dependent than background aerosol optical depths. Forest fire smoke optical depths, however, showed a wide range of wavelength depedences, such as incidents of wavelength-independent extinction.

Impact of ultraviolet radiation treatments on the quality of freshly prepared tomato (Solanum lycopersicum) juice.

PubMed

Bhat, Rajeev

2016-12-15

Impact of ultraviolet (UV-C) radiation treatments (0, 15, 30 and 60min) on freshly extracted tomato juice quality (physicochemical properties, antioxidant activity and microbial load) was evaluated. On exposure to UV-C, level of water activity, total soluble solids, and titratable acidity exhibited non-significant increase up to 30min of exposure time. Regarding colour analysis, L∗ value significantly increased with subsequent decrease in a∗ and b∗ values post UV-C treatments. Clarity, DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and total phenolics content significantly increased, whereas ascorbic acid level significantly reduced at 60min of UV-C exposure time. So also, lycopene content exhibited a non-significant decrease after UV-C treatment. Microbial studies showed reduction in total plate count and total mould counts post UV-C treatment. Overall, UV-C treatment being a physical, non-thermal method of food preservation holds the ability to improve or preserve vital quality parameters in freshly prepared tomato juices, and henceforth possesses high scope for commercial exploration. Copyright © 2016 Elsevier Ltd. All rights reserved.

A new methodology for the assessment of hand protection from ultraviolet exposure.

PubMed

Khazova, M; O'Hagan, J B; Grainger, K J-L

2006-01-01

A number of industrial applications and public services involve occupational exposure to ultraviolet radiation (UVR) from a variety of lamps and lasers. The aim of this study was to develop a methodology for the assessment of the UV protection level for disposable gloves. Glove UV protection factor is defined as a time-scale increase in exposure permitted for the hand protected by a glove with respect to an unprotected hand. Our study showed that for all tested gloves a change in UVR attenuation with stretching is characteristic for the type of glove material and can be included as a scaling factor in the definition of UVR protection. Glove material has a bigger effect on UVR protection level than variations in the glove thickness or its colour. Examples of assessment of the 'worst case scenario' are compared with the protection level against a number of sources, together with the guidance on a simplified evaluation protocol. An application-specific assessment, illustrated for 'SmartWater' forensic examinations and biological trans-illuminators, demonstrates that some gloves provide inadequate protection against occupational UV exposure.

Protection against ultraviolet radiation by commercial summer clothing: need for standardised testing and labelling.

PubMed

Gambichler, T; Rotterdam, S; Altmeyer, P; Hoffmann, K

2001-01-01

The use of clothing as a means of sun protection has been recommended in recent education campaigns. Contrary to popular opinion, however, some fabrics provide insufficient ultraviolet (UV) protection. We investigated 236 apparel textiles of the spring/summer collections 2000 and 2001. In accordance with the forthcoming European standard the UV protection factor (UPF) of the fabrics was determined spectrophotometrically. Seventy-eight (33%) fabrics had UPF < 15, 45 (19%) had UPF = or > 15 and < 30, and 113 (48%) had UPF = or > 30 (30+). More than 70% of the wool, polyester, and fabric blends, and only less than 30% of the cotton, linen, and viscose fabrics had UPF values of 30+. Fabrics with black, navy-blue, white, green, or beige colours provided most frequently UPF values of 30+. It is difficult for the sun-aware consumer to choose the 'right' garment, with a third of summer clothing providing insufficient UV protection and only half of the fabrics having UPF 30+, the UPF recommended by the European standard. Therefore, apparel summer fabrics should be measured and labelled in accordance with a standard document.

Long-term memory of hierarchical relationships in free-living greylag geese.

PubMed

Weiss, Brigitte M; Scheiber, Isabella B R

2013-01-01

Animals may memorise spatial and social information for many months and even years. Here, we investigated long-term memory of hierarchically ordered relationships, where the position of a reward depended on the relationship of a stimulus relative to other stimuli in the hierarchy. Seventeen greylag geese (Anser anser) had been trained on discriminations between successive pairs of five or seven implicitly ordered colours, where the higher ranking colour in each pair was rewarded. Geese were re-tested on the task 2, 6 and 12 months after learning the dyadic colour relationships. They chose the correct colour above chance at all three points in time, whereby performance was better in colour pairs at the beginning or end of the colour series. Nonetheless, they also performed above chance on internal colour pairs, which is indicative of long-term memory for quantitative differences in associative strength and/or for relational information. There were no indications for a decline in performance over time, indicating that geese may remember dyadic relationships for at least 6 months and probably well over 1 year. Furthermore, performance in the memory task was unrelated to the individuals' sex and their performance while initially learning the dyadic colour relationships. We discuss possible functions of this long-term memory in the social domain.

Differential age-related effects on conjunctive and relational visual short-term memory binding.

PubMed

Bastin, Christine

2017-12-28

An age-related associative deficit has been described in visual short-term binding memory tasks. However, separate studies have suggested that ageing disrupts relational binding (to associate distinct items or item and context) more than conjunctive binding (to integrate features within an object). The current study directly compared relational and conjunctive binding with a short-term memory task for object-colour associations in 30 young and 30 older adults. Participants studied a number of object-colour associations corresponding to their individual object span level in a relational task in which objects were associated to colour patches and a conjunctive task where colour was integrated into the object. Memory for individual items and for associations was tested with a recognition memory test. Evidence for an age-related associative deficit was observed in the relational binding task, but not in the conjunctive binding task. This differential impact of ageing on relational and conjunctive short-term binding is discussed by reference to two underlying age-related cognitive difficulties: diminished hippocampally dependent binding and attentional resources.

Colour vision requirements in visually demanding occupations.

PubMed

Barbur, J L; Rodriguez-Carmona, M

2017-06-01

Normal trichromatic colour vision (CV) is often required as a condition for employment in visually demanding occupations. If this requirement could be enforced using current, colour assessment tests, a significant percentage of subjects with anomalous, congenital trichromacy who can perform the suprathreshold, colour-related tasks encountered in many occupations with the same accuracy as normal trichromats would fail. These applicants would therefore be discriminated against unfairly. One solution to this problem is to produce minimum, justifiable CV requirements that are specific to each occupation. This has been done successfully for commercial aviation (i.e. the flight crew) and for Transport for London train drivers. An alternative approach is to make use of new findings and the statistical outcomes of past practices to produce graded, justifiable CV categories that can be enforced. To achieve this aim, we analysed colour assessment outcomes and quantified severity of CV loss in 1363 subjects. The severity of CV loss was measured in each subject and statistical, pass/fail outcomes established for each of the most commonly used, conventional colour assessment tests and protocols. This evidence and new findings that relate severity of loss to the effective use of colour signals in a number of tasks provide the basis for a new colour grading system based on six categories. A single colour assessment test is needed to establish the applicant's CV category which can range from 'supernormal', for the most stringent, colour-demanding tasks, to 'severe colour deficiency', when red/green CV is either absent or extremely weak. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Colour vision deficiency.

PubMed

Simunovic, M P

2010-05-01

Colour vision deficiency is one of the commonest disorders of vision and can be divided into congenital and acquired forms. Congenital colour vision deficiency affects as many as 8% of males and 0.5% of females--the difference in prevalence reflects the fact that the commonest forms of congenital colour vision deficiency are inherited in an X-linked recessive manner. Until relatively recently, our understanding of the pathophysiological basis of colour vision deficiency largely rested on behavioural data; however, modern molecular genetic techniques have helped to elucidate its mechanisms. The current management of congenital colour vision deficiency lies chiefly in appropriate counselling (including career counselling). Although visual aids may be of benefit to those with colour vision deficiency when performing certain tasks, the evidence suggests that they do not enable wearers to obtain normal colour discrimination. In the future, gene therapy remains a possibility, with animal models demonstrating amelioration following treatment.

Attentional capture by masked colour singletons.

PubMed

Ansorge, Ulrich; Horstmann, Gernot; Worschech, Franziska

2010-09-15

We tested under which conditions a colour singleton of which an observer is unaware captures attention. To prevent visual awareness of the colour singleton, we used backward masking. We find that a masked colour singleton cue captures attention if it matches the observer's goal to search for target colours but not if it is task-irrelevant. This is also reflected in event-related potentials to the visible target: the masked goal-matching cue elicits an attentional potential (N2pc) in a target search task. By contrast, a non-matching but equally strong masked colour singleton cue failed to elicit a capture effect and an N2pc. Results are discussed with regard to currently pertaining conceptions of attentional capture by colour singletons. Copyright 2010 Elsevier Ltd. All rights reserved.

Detecting gradual visual changes in colour and brightness agnosia: a double dissociation.

PubMed

Nijboer, Tanja C W; te Pas, Susan F; van der Smagt, Maarten J

2011-03-09

Two patients, one with colour agnosia and one with brightness agnosia, performed a task that required the detection of gradual temporal changes in colour and brightness. The results for these patients, who showed anaverage or an above-average performance on several tasks designed to test low-level colour and luminance (contrast) perception in the spatial domain, yielded a double dissociation; the brightness agnosic patient was within the normal range for the coloured stimuli, but much slower to detect brightness differences, whereas the colour agnosic patient was within the normal range for the achromatic stimuli, but much slower for the coloured stimuli. These results suggest that a modality-specific impairment in the detection of gradual temporal changes might be related to, if not underlie, the phenomenon of visual agnosia.

Floral colour versus phylogeny in structuring subalpine flowering communities.

PubMed

McEwen, Jamie R; Vamosi, Jana C

2010-10-07

The relative number of seeds produced by competing species can influence the community structure; yet, traits that influence seed production, such as pollinator attraction and floral colour, have received little attention in community ecology. Here, we analyse floral colour using reflectance spectra that include near-UV and examined the phylogenetic signal of floral colour. We found that coflowering species within communities tended to be more divergent in floral colour than expected by chance. However, coflowering species were not phylogenetically dispersed, in part due to our finding that floral colour is a labile trait with a weak phylogenetic signal. Furthermore, while we found that locally rare and common species exhibited equivalent floral colour distances from their coflowering neighbours, frequent species (those found in more communities) exhibited higher colour distances from their coflowering neighbours. Our findings support recent studies, which have found that (i) plant lineages exhibit frequent floral colour transitions; and (ii) traits that influence local population dynamics contribute to community structure.

Human colour in mate choice and competition.

PubMed

Rowland, Hannah M; Burriss, Robert P

2017-07-05

The colour of our skin and clothing affects how others perceive us and how we behave. Human skin colour varies conspicuously with genetic ancestry, but even subtle changes in skin colour due to diet, blood oxygenation and hormone levels influence social perceptions. In this review, we describe the theoretical and empirical frameworks in which human colour is researched. We explore how subtle skin colour differences relate to judgements of health and attractiveness. Also, because humans are one of the few organisms able to manipulate their apparent colour, we review how cosmetics and clothing are implicated in courtship and competition, both inside the laboratory and in the real world. Research on human colour is in its infancy compared with human psychophysics and colour research in non-human animals, and hence we present best-practice guidelines for methods and reporting, which we hope will improve the validity and reproducibility of studies on human coloration.This article is part of the themed issue 'Animal coloration: production, perception, function and application'. © 2017 The Author(s).

Measurement system to determine the total and angle-resolved light scattering of optical components in the deep-ultraviolet and vacuum-ultraviolet spectral regions

NASA Astrophysics Data System (ADS)

Schröder, Sven; Gliech, Stefan; Duparré, Angela

2005-10-01

An instrumentation for total and angle-resolved scattering (ARS) at 193 and 157 nm has been developed at the Fraunhofer Institute in Jena to meet the severe requirements for scattering analysis of deep- and vacuum-ultraviolet optical components. Extremely low backscattering levels of 10^-6 for the total scattering measurements and more than 9 orders of magnitude dynamic range for ARS have been accomplished. Examples of application extend from the control of at-wavelength scattering losses of superpolished substrates with rms roughness as small as 0.1 nm to the detection of volume material scattering and the study into the scattering of multilayer coatings. In addition, software programs were developed to model the roughness-induced light scattering of substrates and thin-film coatings.

Colour blindness in everyday life and car driving.

PubMed

Tagarelli, Antonio; Piro, Anna; Tagarelli, Giuseppe; Lantieri, Pasquale Bruno; Risso, Domenico; Olivieri, Rosario Luciano

2004-08-01

The aim of the present work was to ascertain, through the administration of a psychosocial questionnaire, the difficulties that subjects with defective colour vision experience in carrying out everyday tasks and work, including driving a car with a driver's licence held for no more than 3 years. Subjects with defective colour vision (n = 151) and subjects with normal vision (n = 302) completed a psychosocial questionnaire regarding the difficulties associated with congenital colour vision deficiency in daily life, work and driving a car. Subjects were diagnosed as colour-blind using the Ishihara test. Statistically significant differences between the two samples were found for daily life activities. Subjects with defective colour vision preferred daytime driving. At night, subjects with defective colour vision had difficulty identifying reflectors on the road and the rear signal lights of cars ahead of them. Colour-blind Calabrian subjects admitted to experiencing colour-related difficulties with a wide range of occupational tasks and leisure pursuits. In particular, colour-blind Calabrian subjects preferred daytime driving, and fewer drove regularly, compared to orthochromatics, who were indifferent to night or daytime driving.

Quantifying plant colour and colour difference as perceived by humans using digital images.

PubMed

Kendal, Dave; Hauser, Cindy E; Garrard, Georgia E; Jellinek, Sacha; Giljohann, Katherine M; Moore, Joslin L

2013-01-01

Human perception of plant leaf and flower colour can influence species management. Colour and colour contrast may influence the detectability of invasive or rare species during surveys. Quantitative, repeatable measures of plant colour are required for comparison across studies and generalisation across species. We present a standard method for measuring plant leaf and flower colour traits using images taken with digital cameras. We demonstrate the method by quantifying the colour of and colour difference between the flowers of eleven grassland species near Falls Creek, Australia, as part of an invasive species detection experiment. The reliability of the method was tested by measuring the leaf colour of five residential garden shrub species in Ballarat, Australia using five different types of digital camera. Flowers and leaves had overlapping but distinct colour distributions. Calculated colour differences corresponded well with qualitative comparisons. Estimates of proportional cover of yellow flowers identified using colour measurements correlated well with estimates obtained by measuring and counting individual flowers. Digital SLR and mirrorless cameras were superior to phone cameras and point-and-shoot cameras for producing reliable measurements, particularly under variable lighting conditions. The analysis of digital images taken with digital cameras is a practicable method for quantifying plant flower and leaf colour in the field or lab. Quantitative, repeatable measurements allow for comparisons between species and generalisations across species and studies. This allows plant colour to be related to human perception and preferences and, ultimately, species management.

Quantifying Plant Colour and Colour Difference as Perceived by Humans Using Digital Images

PubMed Central

Kendal, Dave; Hauser, Cindy E.; Garrard, Georgia E.; Jellinek, Sacha; Giljohann, Katherine M.; Moore, Joslin L.

2013-01-01

Human perception of plant leaf and flower colour can influence species management. Colour and colour contrast may influence the detectability of invasive or rare species during surveys. Quantitative, repeatable measures of plant colour are required for comparison across studies and generalisation across species. We present a standard method for measuring plant leaf and flower colour traits using images taken with digital cameras. We demonstrate the method by quantifying the colour of and colour difference between the flowers of eleven grassland species near Falls Creek, Australia, as part of an invasive species detection experiment. The reliability of the method was tested by measuring the leaf colour of five residential garden shrub species in Ballarat, Australia using five different types of digital camera. Flowers and leaves had overlapping but distinct colour distributions. Calculated colour differences corresponded well with qualitative comparisons. Estimates of proportional cover of yellow flowers identified using colour measurements correlated well with estimates obtained by measuring and counting individual flowers. Digital SLR and mirrorless cameras were superior to phone cameras and point-and-shoot cameras for producing reliable measurements, particularly under variable lighting conditions. The analysis of digital images taken with digital cameras is a practicable method for quantifying plant flower and leaf colour in the field or lab. Quantitative, repeatable measurements allow for comparisons between species and generalisations across species and studies. This allows plant colour to be related to human perception and preferences and, ultimately, species management. PMID:23977275

Fruit over sunbed: carotenoid skin colouration is found more attractive than melanin colouration.

PubMed

Lefevre, Carmen E; Perrett, David I

2015-01-01

Skin colouration appears to play a pivotal part in facial attractiveness. Skin yellowness contributes to an attractive appearance and is influenced both by dietary carotenoids and by melanin. While both increased carotenoid colouration and increased melanin colouration enhance apparent health in Caucasian faces by increasing skin yellowness, it remains unclear, firstly, whether both pigments contribute to attractiveness judgements, secondly, whether one pigment is clearly preferred over the other, and thirdly, whether these effects depend on the sex of the face. Here, in three studies, we examine these questions using controlled facial stimuli transformed to be either high or low in (a) carotenoid colouration, or (b) melanin colouration. We show, firstly, that both increased carotenoid colouration and increased melanin colouration are found attractive compared to lower levels of these pigments. Secondly, we show that carotenoid colouration is consistently preferred over melanin colouration when levels of colouration are matched. In addition, we find an effect of the sex of stimuli with stronger preferences for carotenoids over melanin in female compared to male faces, irrespective of the sex of the observer. These results are interpreted as reflecting preferences for sex-typical skin colouration: men have darker skin than women and high melanization in male faces may further enhance this masculine trait, thus carotenoid colouration is not less desirable, but melanin colouration is relatively more desirable in males compared to females. Taken together, our findings provide further support for a carotenoid-linked health-signalling system that is highly important in mate choice.

Optical properties of the uropygial gland secretion: no evidence for UV cosmetics in birds

NASA Astrophysics Data System (ADS)

Delhey, Kaspar; Peters, Anne; Biedermann, Peter H. W.; Kempenaers, Bart

2008-10-01

Ultraviolet (UV) reflectance of the plumage is common in birds and plays an important role in sexual signalling. Recently, it has been proposed that birds are able to modify plumage UV reflectance by the application of uropygial gland secretion. Based on a survey of the optical properties of this secretion from 51 species belonging to 12 avian orders, we show that two main types of uropygial secretions exist, one predominantly found in passerines and one in non-passerines, both reducing relative UV reflectance of a white background (Teflon™ tape). We quantified how each type of secretion (exemplified by blue tit and mallard) affected feather UV reflectance. Both secretions reduced overall brightness and relative UV reflectance of white mallard feathers but hardly affected the reflectance of UV/blue blue tit crown feathers. According to models of avian colour vision, changes in reflectance due to application of the secretion were at or below the discrimination threshold of most birds. We conclude that the uropygial secretion is unlikely to play a major role in modifying plumage UV reflectance. However, the optical properties of the uropygial secretion may have been selected to interfere as little as possible with visual signaling through plumage reflectance.

Effects of personal experiences on the interpretation of the meaning of colours used in the displays and controls in electric control panels.

PubMed

Lee, Inseok; Hwang, Won-Gue

2015-01-01

A survey was conducted to examine how personal experiences affect the interpretation of the meaning of display and control colours on electric control panels (ECPs). In Korea, the red light on ECPs represents a normal state of operation, while the green light represents a stopped state of operation; this appears to contradict the general stereotypes surrounding these colours. The survey results indicated that the participants who had experience in using ECPs interpreted the colour meaning differently from the other participant group. More than half of the experienced participants regarded the coloured displays and controls as they were designed, while most participants in the other group appeared to interpret the colours in accordance with the stereotypes. It is presumed that accidents related to human errors can occur when non-experienced people use the ECPs, which are easily accessible in many buildings. Practitioner Summary: A survey was conducted to investigate how personal experiences affect the interpretation of the function meanings of coloured lights on electrical control panels. It was found that the interpretation varies according to personal experiences, which can induce accidents related to human errors while operating electrical equipment.

Contingency learning without awareness: evidence for implicit control.

PubMed

Schmidt, James R; Crump, Matthew J C; Cheesman, Jim; Besner, Derek

2007-06-01

The results of four experiments provide evidence for controlled processing in the absence of awareness. Participants identified the colour of a neutral distracter word. Each of four words (e.g., MOVE) was presented in one of the four colours 75% of the time (Experiments 1 and 4) or 50% of the time (Experiments 2 and 3). Colour identification was faster when the words appeared in the colour they were most often presented in relative to when they appeared in another colour, even for participants who were subjectively unaware of any contingencies between the words and the colours. An analysis of sequence effects showed that participants who were unaware of the relation between distracter words and colours nonetheless controlled the impact of the word on performance depending on the nature of the previous trial. A block analysis of contingency-unaware participants revealed that contingencies were learned rapidly in the first block of trials. Experiment 3 showed that the contingency effect does not depend on the level of awareness, thus ruling out explicit strategy accounts. Finally, Experiment 4 showed that the contingency effect results from behavioural control and not from semantic association or stimulus familiarity. These results thus provide evidence for implicit control.

Bad Colourmaps Can Hide Big Structures

NASA Astrophysics Data System (ADS)

Kovesi, Peter

2014-05-01

Colourmaps are often selected with little awareness of the perceptual distortions they might introduce. A colourmap can be thought of as a line or curve drawn through a three dimensional colour space. Individual data values are mapped to positions along this line which, in turn, allows them to be mapped to a colour. For a colourmap to be effective it is important that the perceptual contrast that occurs as one moves along the line in the colour space is close to uniform. Many colourmaps are designed as piecewise linear paths through RGB space. This is a poor colour space to use because it is not perceptually uniform. Accordingly many colourmaps supplied by vendors have uneven perceptual contrast over their range. They may include points of locally high colour contrast leading you to think there might be some anomaly in your data when there is none. Conversely, colourmaps may also have flat spots of low perceptual contrast that prevent you from seeing features in your data. In some cases it is possible for structures having a magnitude of 10% of the full data range to be completely hidden by a flat spot in the colourmap. The deficiencies of many colourmaps can be revealed using a simple test image consisting of a high frequency sine wave superimposed on a ramp function. The amplitude of the sine wave is modulated from a maximum value at the top of the image to zero at the bottom. Ideally the sine wave should be uniformly visible across the image at all points on the ramp. For many colourmaps this will not be the case. At the very bottom of the image, where the sine wave amplitude has been modulated to 0, we just have a linear ramp which simply reproduces the colourmap. Given that the underlying data is a featureless ramp the colourmap should not induce the perception of any features across the bottom of the test image. Good colourmaps are difficult to design. A greyscale colourmap is generally a safe choice but is not always what is desired. For non-greyscale colourmaps the perceptual colour contrast between adjacent entries of the map should be constant across the whole colourmap. In addition, and more importantly, the colour lightness change between successive entries in the colourmap should also be constant. These conditions, if observed, constrain the design of colourmaps considerably, and they exclude the construction of rainbow style colourmaps. It is shown that good colourmaps can be formed from smooth curves constructed in a perceptually uniform colour space such as CIELAB. Colour lightness values should be monotonically increasing at a constant rate while at the same time the colourmap curve should stay close to the boundary of the colour space gamut to ensure that the colours are vivid.

The interaction of ultraviolet light with Arctic sea ice during SHEBA

NASA Astrophysics Data System (ADS)

Perovich, Donald K.

The reflection, absorption and transmission of ultraviolet light by a sea-ice cover strongly impacts primary productivity, higher trophic components of the food web, and humans. Measurements of the incident irradiance at 305, 320, 340 and 380 nm and of the photosynthetically active radiation were made from April through September 1998 as part of the SHEBA (Surface Heat Budget of the Arctic Ocean program) field experiment in the Arctic Ocean. In addition, observations of snow depth and ice thickness were made at more than 100 sites encompassing a comprehensive range of conditions. The thickness observations were combined with a radiative transfer model to compute a time series of the ultraviolet light transmitted by the ice cover from April through September. Peak values of incident ultraviolet irradiance occurred in mid-June. Peak transmittance was later in the summer at the end of the melt season when the snow cover had completely melted, the ice had thinned and pond coverage was extensive. The fraction of the incident ultraviolet irradiance transmitted through the ice increased by several orders of magnitude as the melt season progressed. Ultraviolet transmittance was approximately a factor of ten greater for melt ponds than bare ice. Climate change has the potential to alter the amplitude and timing of the annual albedo cycle of sea ice. If the onset of melt occurs at increasingly earlier dates, ultraviolet transmittance will be significantly enhanced, with potentially deleterious biological impacts.

The colour of pain: can patients use colour to describe osteoarthritis pain?

PubMed

Wylde, Vikki; Wells, Victoria; Dixon, Samantha; Gooberman-Hill, Rachael

2014-03-01

The aim of the present study was to explore patients' views on the acceptability and feasibility of using colour to describe osteoarthritis (OA) pain, and whether colour could be used to communicate pain to healthcare professionals. Six group interviews were conducted with 17 patients with knee OA. Discussion topics included first impressions about using colour to describe pain, whether participants could associate their pain with colour, how colours related to changes to intensity and different pain qualities, and whether they could envisage using colour to describe pain to healthcare professionals. The group interviews indicated that, although the idea of using colour was generally acceptable, it did not suit all participants as a way of describing their pain. The majority of participants chose red to describe high-intensity pain; the reasons given were because red symbolized inflammation, fire, anger and the stop signal in a traffic light system. Colours used to describe the absence of pain were chosen because of their association with positive emotional feelings, such as purity, calmness and happiness. A range of colours was chosen to represent changes in pain intensity. Aching pain was consistently identified as being associated with colours such as grey or black, whereas sharp pain was described using a wider selection of colours. The majority of participants thought that they would be able to use colour to describe their pain to healthcare professionals, although issues around the interpretability and standardization of colour were raised. For some patients, using colour to describe their pain experience may be a useful tool to improve doctor-patient communication. Copyright © 2013 John Wiley & Sons, Ltd.

Synaesthetic colour in the brain: beyond colour areas. A functional magnetic resonance imaging study of synaesthetes and matched controls.

PubMed

van Leeuwen, Tessa M; Petersson, Karl Magnus; Hagoort, Peter

2010-08-10

In synaesthesia, sensations in a particular modality cause additional experiences in a second, unstimulated modality (e.g., letters elicit colour). Understanding how synaesthesia is mediated in the brain can help to understand normal processes of perceptual awareness and multisensory integration. In several neuroimaging studies, enhanced brain activity for grapheme-colour synaesthesia has been found in ventral-occipital areas that are also involved in real colour processing. Our question was whether the neural correlates of synaesthetically induced colour and real colour experience are truly shared. First, in a free viewing functional magnetic resonance imaging (fMRI) experiment, we located main effects of synaesthesia in left superior parietal lobule and in colour related areas. In the left superior parietal lobe, individual differences between synaesthetes (projector-associator distinction) also influenced brain activity, confirming the importance of the left superior parietal lobe for synaesthesia. Next, we applied a repetition suppression paradigm in fMRI, in which a decrease in the BOLD (blood-oxygenated-level-dependent) response is generally observed for repeated stimuli. We hypothesized that synaesthetically induced colours would lead to a reduction in BOLD response for subsequently presented real colours, if the neural correlates were overlapping. We did find BOLD suppression effects induced by synaesthesia, but not within the colour areas. Because synaesthetically induced colours were not able to suppress BOLD effects for real colour, we conclude that the neural correlates of synaesthetic colour experience and real colour experience are not fully shared. We propose that synaesthetic colour experiences are mediated by higher-order visual pathways that lie beyond the scope of classical, ventral-occipital visual areas. Feedback from these areas, in which the left parietal cortex is likely to play an important role, may induce V4 activation and the percept of synaesthetic colour.

The Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS): survey design, data catalogue and GAMA/WiggleZ spectroscopy

NASA Astrophysics Data System (ADS)

Ching, John H. Y.; Sadler, Elaine M.; Croom, Scott M.; Johnston, Helen M.; Pracy, Michael B.; Couch, Warrick J.; Hopkins, A. M.; Jurek, Russell J.; Pimbblet, K. A.

2017-01-01

We present the Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS), a spectroscopic catalogue of radio sources designed to include the full range of radio AGN populations out to redshift z ˜ 0.8. The catalogue covers ˜800 deg2 of sky, and provides optical identifications for 19 179 radio sources from the 1.4 GHz Faint Images of the Radio Sky at Twenty-cm (FIRST) survey down to an optical magnitude limit of Imod < 20.5 in Sloan Digital Sky Survey (SDSS) images. Both galaxies and point-like objects are included, and no colour cuts are applied. In collaboration with the WiggleZ and Galaxy And Mass Assembly (GAMA) spectroscopic survey teams, we have obtained new spectra for over 5000 objects in the LARGESS sample. Combining these new spectra with data from earlier surveys provides spectroscopic data for 12 329 radio sources in the survey area, of which 10 856 have reliable redshifts. 85 per cent of the LARGESS spectroscopic sample are radio AGN (median redshift z = 0.44), and 15 per cent are nearby star-forming galaxies (median z = 0.08). Low-excitation radio galaxies (LERGs) comprise the majority (83 per cent) of LARGESS radio AGN at z < 0.8, with 12 per cent being high-excitation radio galaxies (HERGs) and 5 per cent radio-loud QSOs. Unlike the more homogeneous LERG and QSO sub-populations, HERGs are a heterogeneous class of objects with relatively blue optical colours and a wide dispersion in mid-infrared colours. This is consistent with a picture in which most HERGs are hosted by galaxies with recent or ongoing star formation as well as a classical accretion disc.

Directional sexual selection on chroma and within-pattern colour contrast in Labeotropheus fuelleborni.

PubMed

Pauers, Michael J; McKinnon, Jeffrey S; Ehlinger, Timothy J

2004-12-07

Speciation via intersexual selection on male nuptial colour pattern is thought to have been a major force in promoting the explosive speciation of African haplochromine cichlids, yet there is very little direct empirical evidence of directional preferences within populations. In this study, we used objective spectrophotometry and analyses based on visual physiology to determine whether females of the Katale population of Labeotropheus fuelleborni, a Lake Malawi haplochromine, prefer males that have higher chroma and more within-pattern colour contrast. In paired male preference tests, female Katale L. fuelleborni showed increasing preferences for males with more relatively saturated colours on their flanks. They also showed increasing preferences for males with relatively higher contrast levels among flank elements. This is the first empirical evidence, to our knowledge, for male colour as a directionally sexually selected trait within a haplochromine cichlid population.

Directional sexual selection on chroma and within-pattern colour contrast in Labeotropheus fuelleborni.

PubMed Central

Pauers, Michael J; McKinnon, Jeffrey S; Ehlinger, Timothy J

2004-01-01

Speciation via intersexual selection on male nuptial colour pattern is thought to have been a major force in promoting the explosive speciation of African haplochromine cichlids, yet there is very little direct empirical evidence of directional preferences within populations. In this study, we used objective spectrophotometry and analyses based on visual physiology to determine whether females of the Katale population of Labeotropheus fuelleborni, a Lake Malawi haplochromine, prefer males that have higher chroma and more within-pattern colour contrast. In paired male preference tests, female Katale L. fuelleborni showed increasing preferences for males with more relatively saturated colours on their flanks. They also showed increasing preferences for males with relatively higher contrast levels among flank elements. This is the first empirical evidence, to our knowledge, for male colour as a directionally sexually selected trait within a haplochromine cichlid population. PMID:15801599

Colouration in amphibians as a reflection of nutritional status: The case of tree frogs in Costa Rica

PubMed Central

2017-01-01

Colouration has been considered a cue for mating success in many species; ornaments in males often are related to carotenoid mobilization towards feathers and/or skin and can signal general health and nutrition status. However, there are several factors that can also link with status, such as physiological blood parameters and body condition, but there is not substantial evidence which supports the existence of these relationships and interactions in anurans. This study evaluated how body score and blood values interact with colouration in free-range Agalychnis callidryas and Agalychnis annae males. We found significant associations between body condition and plasmatic proteins and haematocrit, as well as between body condition and colour values from the chromaticity diagram. We also demonstrated that there is a significant relation between the glucose and plasmatic protein values that were reflected in the ventral colours of the animals, and haematocrit inversely affected most of those colour values. Significant differences were found between species as well as between populations of A. callidryas, suggesting that despite colour variation, there are also biochemical differences within animals from the same species located in different regions. These data provide information on underlying factors for colouration of male tree frogs in nature, provide insights about the dynamics of several nutrients in the amphibian model and how this could affect the reproductive output of the animals. PMID:28837604

Colour-specific differences in attentional deployment for equiluminant pop-out colours: evidence from lateralised potentials.

PubMed

Pomerleau, Vincent Jetté; Fortier-Gauthier, Ulysse; Corriveau, Isabelle; Dell'Acqua, Roberto; Jolicœur, Pierre

2014-03-01

We investigated how target colour affected behavioural and electrophysiological results in a visual search task. Perceptual and attentional mechanisms were tracked using the N2pc component of the event-related potential and other lateralised components. Four colours (red, green, blue, or yellow) were calibrated for each participant for luminance through heterochromatic flicker photometry and equated to the luminance of grey distracters. Each visual display contained 10 circles, 1 colored and 9 grey, each of which contained an oriented line segment. The task required deploying attention to the colored circle, which was either in the left or right visual hemifield. Three lateralised ERP components relative to the side of the lateral coloured circle were examined: a posterior contralateral positivity (Ppc) prior to N2pc, the N2pc, reflecting the deployment of visual spatial attention, and a temporal and contralateral positivity (Ptc) following N2pc. Red or blue stimuli, as compared to green or yellow, had an earlier N2pc. Both the Ppc and Ptc had higher amplitudes to red stimuli, suggesting particular selectivity for red. The results suggest that attention may be deployed to red and blue more quickly than to other colours and suggests special caution when designing ERP experiments involving stimuli in different colours, even when all colours are equiluminant. Copyright © 2013 Elsevier B.V. All rights reserved.

Easier detection of invertebrate "identification-key characters" with light of different wavelengths

PubMed Central

2011-01-01

The marine α-taxonomist often encounters two problems. Firstly, the "environmental dirt" that is frequently present on the specimens and secondly the difficulty in distinguishing key-features due to the uniform colours which fixed animals often adopt. Here we show that illuminating animals with deep-blue or ultraviolet light instead of the normal white-light abrogates both difficulties; dirt disappears and important details become clearly visible. This light regime has also two other advantages. It allows easy detection of very small, normally invisible, animals (0.1 μm range). And as these light wavelengths can induce fluorescence, new identification markers may be discovered by this approach. PMID:22040277

Do all barium stars have a white dwarf companion?

NASA Technical Reports Server (NTRS)

Dominy, J. F.; Lambert, D. L.

1983-01-01

International Ultraviolet Explorer short-wavelength, low-dispersion spectra were analyzed for four barium, two mild barium, and one R-type carbon star in order to test the hypothesis that the barium and related giants are produced by mass transfer from a companion now present as a white dwarf. An earlier tentative identification of a white dwarf companion to the mild barium star Zeta Cyg is confirmed. For the other stars, no ultraviolet excess attributable to a white dwarf is seen. Limits are set on the bolometric magnitude and age of a possible white dwarf companion. Since the barium stars do not have obvious progenitors among main-sequence and subgiant stars, mass transfer must be presumed to occur when the mass-gaining star is already on the giant branch. This restriction, and the white dwarf's minimum age, which is greater than 8 x 10 to the 8th yr, determined for several stars, effectively eliminates the hypothesis that mass transfer from an asymptotic giant branch star creates a barium star. Speculations are presented on alternative methods of producing a barium star in a binary system.

High-resolution UV-visible spectroscopy of lunar red spots

NASA Technical Reports Server (NTRS)

Bruno, B. C.; Lucey, P. G.; Hawke, B. R.

1991-01-01

A spectral reflectance study of selected lunar 'red spots', highland areas characterized by an absorption in the ultraviolet relative to the visible was conducted. Some red spots were suggested to be the sites of ancient highland volcanism. High-resolution spectral data of eight red spots on the western portion of the moon over the wavelength region 0.39-0.82 micron were obtained. Much spectral variation among these red spots in the magnitude as well as the wavelength position of the ultraviolet absorption were found. Spectral structure at visible and near-infrared wavelength were also identified. These spectral differences indicate that red spots do not have a single mineralogical composition, which in turn suggests that red spots may have multiple origins. Additional imaging spectroscopic observations were taken of the Herigonius red spot, a morphologically complex region northeast of Mare Humorum. These data reveal significant spectral differences among the various morphological units within the Herigonius red spot. Although some of these are likely due to the effects of the maturation process, others appear to reflect differences in mineral abundances and composition.

Observations of Comet Levy (1990c) with the Hopkins Ultraviolet Telescope

NASA Technical Reports Server (NTRS)

Feldman, P. D.; Davidsen, A. F.; Blair, W. P.; Bowers, C. W.; Dixon, W. V.; Durrance, S. T.; Henry, R. C.; Ferguson, H. C.; Kimble, R. A.; Gull, Theodore R.

1991-01-01

Observations of Comet Levy (1990c) were made with the Hopkins Ultraviolet Telescope during the Astro-1 Space Shuttle mission on December 10, 1990. The spectrum, covering the wavelength range 415-1850 A at a spectral resolution of 3 A, shows the presence of carbon monoxide and atomic hydrogen, carbon, and sulfur in the coma. Aside from H I Lyman-beta, no cometary features are detected below 1200 A, although cometary O I and O II would be masked by the same emissions present in the day airglow spectrum. The 9.4 x 116 arcsecond aperture corresponds to 12,000 x 148,000 km at the comet. The derived production rate of CO relative to water is 0.11 + or - 0.02, compared with 0.04 + or - 0.01 derived from IUE observations (made in September 1990) which sample a much smaller region of the coma. This suggests the presence of an extended source of CO, as was found in comet Halley. Upper limits on Ne and Ar abundance are within one order of magnitude of solar abundances.

Three spectrally distinct photoreceptors in diurnal and nocturnal Australian ants.

PubMed

Ogawa, Yuri; Falkowski, Marcin; Narendra, Ajay; Zeil, Jochen; Hemmi, Jan M

2015-06-07

Ants are thought to be special among Hymenopterans in having only dichromatic colour vision based on two spectrally distinct photoreceptors. Many ants are highly visual animals, however, and use vision extensively for navigation. We show here that two congeneric day- and night-active Australian ants have three spectrally distinct photoreceptor types, potentially supporting trichromatic colour vision. Electroretinogram recordings show the presence of three spectral sensitivities with peaks (λmax) at 370, 450 and 550 nm in the night-active Myrmecia vindex and peaks at 370, 470 and 510 nm in the day-active Myrmecia croslandi. Intracellular electrophysiology on individual photoreceptors confirmed that the night-active M. vindex has three spectral sensitivities with peaks (λmax) at 370, 430 and 550 nm. A large number of the intracellular recordings in the night-active M. vindex show unusually broad-band spectral sensitivities, suggesting that photoreceptors may be coupled. Spectral measurements at different temporal frequencies revealed that the ultraviolet receptors are comparatively slow. We discuss the adaptive significance and the probability of trichromacy in Myrmecia ants in the context of dim light vision and visual navigation. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Spectral Diversity and Regulation of Coral Fluorescence in a Mesophotic Reef Habitat in the Red Sea.

PubMed

Eyal, Gal; Wiedenmann, Jörg; Grinblat, Mila; D'Angelo, Cecilia; Kramarsky-Winter, Esti; Treibitz, Tali; Ben-Zvi, Or; Shaked, Yonathan; Smith, Tyler B; Harii, Saki; Denis, Vianney; Noyes, Tim; Tamir, Raz; Loya, Yossi

2015-01-01

The phenomenon of coral fluorescence in mesophotic reefs, although well described for shallow waters, remains largely unstudied. We found that representatives of many scleractinian species are brightly fluorescent at depths of 50-60 m at the Interuniversity Institute for Marine Sciences (IUI) reef in Eilat, Israel. Some of these fluorescent species have distribution maxima at mesophotic depths (40-100 m). Several individuals from these depths displayed yellow or orange-red fluorescence, the latter being essentially absent in corals from the shallowest parts of this reef. We demonstrate experimentally that in some cases the production of fluorescent pigments is independent of the exposure to light; while in others, the fluorescence signature is altered or lost when the animals are kept in darkness. Furthermore, we show that green-to-red photoconversion of fluorescent pigments mediated by short-wavelength light can occur also at depths where ultraviolet wavelengths are absent from the underwater light field. Intraspecific colour polymorphisms regarding the colour of the tissue fluorescence, common among shallow water corals, were also observed for mesophotic species. Our results suggest that fluorescent pigments in mesophotic reefs fulfil a distinct biological function and offer promising application potential for coral-reef monitoring and biomedical imaging.

Effect of TiO2-Crystal Forms on the Photo-Degradation of EVA/PLA Blend Under Accelerated Weather Testing

NASA Astrophysics Data System (ADS)

Van Cong, Do; Trang, Nguyen Thi Thu; Giang, Nguyen Vu; Lam, Tran Dai; Hoang, Thai

2016-05-01

Photo-degradation of poly (ethylene-co-vinyl acetate) (EVA)/poly (lactic acid) (PLA) blend and EVA/PLA/TiO2 nanocomposites was carried out under accelerated weather testing conditions by alternating cycles of ultraviolet (UV) light and moisture at controlled and elevated temperatures. The characters, properties, and morphology of these materials before and after accelerated weather testing were determined by Fourier transform infrared spectroscopy, colour changes, viscosity, tensile test, thermogravimetric analysis, and field emission scanning electron microscopy. The increases in the content of oxygen-containing groups, colour changes; the decreases in viscosity, tensile properties, and thermal stability of these materials after accelerated weather testing are the evidence for the photo-degradation of the blend and nanocomposites. After accelerated weather testing, the appearance of many micro-holes and micro-pores on the surface of the collected samples was observed. The photo-degradation degree of the nanocomposites depended on the TiO2-crystal form. Rutile TiO2 do not enhance the degradation, but anatase and mixed crystals TiO2 nanoparticles promoted the degradation of the nanocomposites. Particularly, the mixed crystals TiO2 nanoparticles showed the highest photo-catalytic activity of the nanocomposites.

Properties of Am, Delta Del and Delta SCT stars in the VBLUW system

NASA Astrophysics Data System (ADS)

Wiertz, M. J. J.; van Genderen, A. M.

1983-05-01

VBLUW photometric observations of 115 Am, δ Del, and δ Sct stars are presented and discussed. The spread with respect to the main sequence in the two-colour diagrams is mainly attributed to gravity effects. Temperatures and gravities compare reasonably well with those of Davis Philip et al. (1976) based on uvbyß photometry. However, the temperatures derived by Babu and Shylaja (1981, 1982) and based on spectral energy distribution, reveal that the photometric temperatures (and thus also gravities) are underestimated. The relation between the temperature sensitive colour indices V-B (of the VBLUW system), b-y (ubvyß system) and B2-V1 (Geneva system) for A/F type stars is investigated. A PLC relation for the colour V-B is derived using Breger's (1979) relation for the colour b-y.

Machine-learning identification of galaxies in the WISE × SuperCOSMOS all-sky catalogue

NASA Astrophysics Data System (ADS)

Krakowski, T.; Małek, K.; Bilicki, M.; Pollo, A.; Kurcz, A.; Krupa, M.

2016-11-01

Context. The two currently largest all-sky photometric datasets, WISE and SuperCOSMOS, have been recently cross-matched to construct a novel photometric redshift catalogue on 70% of the sky. Galaxies were separated from stars and quasars through colour cuts, which may leave imperfections because different source types may overlap in colour space. Aims: The aim of the present work is to identify galaxies in the WISE × SuperCOSMOS catalogue through an alternative approach of machine learning. This allows us to define more complex separations in the multi-colour space than is possible with simple colour cuts, and should provide a more reliable source classification. Methods: For the automatised classification we used the support vector machines (SVM) learning algorithm and employed SDSS spectroscopic sources that we cross-matched with WISE × SuperCOSMOS to construct the training and verification set. We performed a number of tests to examine the behaviour of the classifier (completeness, purity, and accuracy) as a function of source apparent magnitude and Galactic latitude. We then applied the classifier to the full-sky data and analysed the resulting catalogue of candidate galaxies. We also compared the resulting dataset with the one obtained through colour cuts. Results: The tests indicate very high accuracy, completeness, and purity (>95%) of the classifier at the bright end; this deteriorates for the faintest sources, but still retains acceptable levels of 85%. No significant variation in the classification quality with Galactic latitude is observed. When we applied the classifier to all-sky WISE × SuperCOSMOS data, we found 15 million galaxies after masking problematic areas. The resulting sample is purer than the one produced by applying colour cuts, at the price of a lower completeness across the sky. Conclusions: The automatic classification is a successful alternative approach to colour cuts for defining a reliable galaxy sample. The identifications we obtained are included in the public release of the WISE × SuperCOSMOS galaxy catalogue. The public release of the WISE × SuperCOSMOS galaxy catalogue is available from http://ssa.roe.ac.uk/WISExSCOS

Young LMC clusters: the role of red supergiants and multiple stellar populations in their integrated light and CMDs

NASA Astrophysics Data System (ADS)

Asa'd, Randa S.; Vazdekis, Alexandre; Cerviño, Miguel; Noël, Noelia E. D.; Beasley, Michael A.; Kassab, Mahmoud

2017-11-01

The optical integrated spectra of three Large Magellanic Cloud young stellar clusters (NGC 1984, NGC 1994 and NGC 2011) exhibit concave continua and prominent molecular bands which deviate significantly from the predictions of single stellar population (SSP) models. In order to understand the appearance of these spectra, we create a set of young stellar population (MILES) models, which we make available to the community. We use archival International Ultraviolet Explorer integrated UV spectra to independently constrain the cluster masses and extinction, and rule out strong stochastic effects in the optical spectra. In addition, we also analyse deep colour-magnitude diagrams of the clusters to provide independent age determinations based on isochrone fitting. We explore hypotheses, including age spreads in the clusters, a top-heavy initial mass function, different SSP models and the role of red supergiant stars (RSG). We find that the strong molecular features in the optical spectra can be only reproduced by modelling an increased fraction of about ˜20 per cent by luminosity of RSG above what is predicted by canonical stellar evolution models. Given the uncertainties in stellar evolution at Myr ages, we cannot presently rule out the presence of Myr age spreads in these clusters. Our work combines different wavelengths as well as different approaches (resolved data as well as integrated spectra for the same sample) in order to reveal the complete picture. We show that each approach provides important information but in combination we can better understand the cluster stellar populations.

The Effect of Colour on Children's Cognitive Performance

ERIC Educational Resources Information Center

Brooker, Alice; Franklin, Anna

2016-01-01

Background: The presence of red appears to hamper adults' cognitive performance relative to other colours (see Elliot & Maier, 2014, "Ann. Rev. Psychol." 65, 95). Aims and sample: Here, we investigate whether colour affects cognitive performance in 8- and 9-year-olds. Method: Children completed a battery of tasks once in the presence…

Application of the differential colorimetry and polyphenolic profile to the evaluation of the chromatic quality of Tempranillo red wines elaborated in warm climate. Influence of the presence of oak wood chips during fermentation.

PubMed

Gordillo, Belén; Cejudo-Bastante, María Jesús; Rodríguez-Pulido, Francisco J; González-Miret, M Lourdes; Heredia, Francisco J

2013-12-01

The effect of adding American oak wood chips during fermentation on Tempranillo red wines elaborates in a warm climate has been studied. Our attention was focused on the tristimulus colorimetry, differential colorimetry and phenolic compounds related to wine colour. This technique was applied as an oenological alternative to the conventional winemaking for avoiding the common fall of colour of red wines elaborated in warm climates. The addition of oak wood chips promoted the colour enhancement and stabilisation, producing wines with a notably darker colour and with more bluish tonality. This fact was also related to the significantly higher content of some phenolic compounds. On the basis of the results, it could be affirmed that the addition of oak wood chips during fermentation induced visually perceptible colour changes (by the analysis of ΔEab(*), %Δ(2)L, %Δ(2)C and %Δ(2)H), mainly in a quantitative way, and also a lower percentage of diminution of colour. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synaesthetic perception of colour and visual space in a blind subject: an fMRI case study.

PubMed

Niccolai, Valentina; van Leeuwen, Tessa M; Blakemore, Colin; Stoerig, Petra

2012-06-01

In spatial sequence synaesthesia (SSS) ordinal stimuli are perceived as arranged in peripersonal space. Using fMRI, we examined the neural bases of SSS and colour synaesthesia for spoken words in a late-blind synaesthete, JF. He reported days of the week and months of the year as both coloured and spatially ordered in peripersonal space; parts of the days and festivities of the year were spatially ordered but uncoloured. Words that denote time-units and triggered no concurrents were used in a control condition. Both conditions inducing SSS activated the occipito-parietal, infero-frontal and insular cortex. The colour area hOC4v was engaged when the synaesthetic experience included colour. These results confirm the continued recruitment of visual colour cortex in this late-blind synaesthetes. Synaesthesia also involved activation in inferior frontal cortex, which may be related to spatial memory and detection, and in the insula, which might contribute to audiovisual integration related to the processing of inducers and concurrents. Copyright © 2012 Elsevier Inc. All rights reserved.

Waveforms for optimal sub-keV high-order harmonics with synthesized two- or three-colour laser fields.

PubMed

Jin, Cheng; Wang, Guoli; Wei, Hui; Le, Anh-Thu; Lin, C D

2014-05-30

High-order harmonics extending to the X-ray region generated in a gas medium by intense lasers offer the potential for providing tabletop broadband light sources but so far are limited by their low conversion efficiency. Here we show that harmonics can be enhanced by one to two orders of magnitude without an increase in the total laser power if the laser's waveform is optimized by synthesizing two- or three-colour fields. The harmonics thus generated are also favourably phase-matched so that radiation is efficiently built up in the gas medium. Our results, combined with the emerging intense high-repetition MHz lasers, promise to increase harmonic yields by several orders to make harmonics feasible in the near future as general bright tabletop light sources, including intense attosecond pulses.

Testing the AUDI2000 colour-difference formula for solid colours using some visual datasets with usefulness to automotive industry

NASA Astrophysics Data System (ADS)

Martínez-García, Juan; Melgosa, Manuel; Gómez-Robledo, Luis; Li, Changjun; Huang, Min; Liu, Haoxue; Cui, Guihua; Luo, M. Ronnier; Dauser, Thomas

2013-11-01

Colour-difference formulas are tools employed in colour industries for objective pass/fail decisions of manufactured products. These objective decisions are based on instrumental colour measurements which must reliably predict the subjective colour-difference evaluations performed by observers' panels. In a previous paper we have tested the performance of different colour-difference formulas using the datasets employed at the development of the last CIErecommended colour-difference formula CIEDE2000, and we found that the AUDI2000 colour-difference formula for solid (homogeneous) colours performed reasonably well, despite the colour pairs in these datasets were not similar to those typically employed in the automotive industry (CIE Publication x038:2013, 465-469). Here we have tested again AUDI2000 together with 11 advanced colour-difference formulas (CIELUV, CIELAB, CMC, BFD, CIE94, CIEDE2000, CAM02-UCS, CAM02-SCD, DIN99d, DIN99b, OSA-GP-Euclidean) for three visual datasets we may consider particularly useful to the automotive industry because of different reasons: 1) 828 metallic colour pairs used to develop the highly reliable RIT-DuPont dataset (Color Res. Appl. 35, 274-283, 2010); 2) printed samples conforming 893 colour pairs with threshold colour differences (J. Opt. Soc. Am. A 29, 883-891, 2012); 3) 150 colour pairs in a tolerance dataset proposed by AUDI. To measure the relative merits of the different tested colour-difference formulas, we employed the STRESS index (J. Opt. Soc. Am. A 24, 1823-1829, 2007), assuming a 95% confidence level. For datasets 1) and 2), AUDI2000 was in the group of the best colour-difference formulas with no significant differences with respect to CIE94, CIEDE2000, CAM02-UCS, DIN99b and DIN99d formulas. For dataset 3) AUDI2000 provided the best results, being statistically significantly better than all other tested colour-difference formulas.

Optical Characterisation of Suspended Particles in the Mackenzie River Plume (Canadian Arctic Ocean) and Implications for Ocean Colour Remote Sensing

NASA Technical Reports Server (NTRS)

Doxaran, D.; Ehn, J.; Belanger, S.; Matsuoka, A.; Hooker, S.; Babin, M.

2012-01-01

Climate change significantly impacts Arctic shelf regions in terms of air temperature, ultraviolet radiation, melting of sea ice, precipitation, thawing of permafrost and coastal erosion. Direct consequences have been observed on the increasing Arctic river flow and a large amount of organic carbon sequestered in soils at high latitudes since the last glacial maximum can be expected to be delivered to the Arctic Ocean during the coming decade. Monitoring the fluxes and fate of this terrigenous organic carbon is problematic in such sparsely populated regions unless remote sensing techniques can be developed and proved to be operational. The main objective of this study is to develop an ocean colour algorithm to operationally monitor dynamics of suspended particulate matter (SPM) on the Mackenzie River continental shelf (Canadian Arctic Ocean) using satellite imagery. The water optical properties are documented across the study area and related to concentrations of SPM and particulate organic carbon (POC). Robust SPM and POC : SPM proxies are identified, such as the light backscattering and attenuation coefficients, and relationships are established between these optical and biogeochemical parameters. Following a semi-analytical approach, a regional SPM quantification relationship is obtained for the inversion of the water reflectance signal into SPM concentration. This relationship is reproduced based on independent field optical measurements. It is successfully applied to a selection of MODIS satellite data which allow estimating fluxes at the river mouth and monitoring the extension and dynamics of the Mackenzie River surface plume in 2009, 2010 and 2011. Good agreement is obtained with field observations representative of the whole water column in the river delta zone where terrigenous SPM is mainly constrained (out of short periods of maximum river outflow). Most of the seaward export of SPM is observed to occur within the west side of the river mouth. Future work will require the validation of the developed SPM regional algorithm based on match-ups with field measurements, then the routine application to ocean colour satellite data in order to better estimate the fluxes and fate of SPM and POC delivered by the Mackenzie River to the Arctic Ocean.

Protoclusters with evolved populations around radio galaxies at z ~ 2.5

NASA Astrophysics Data System (ADS)

Kajisawa, Masaru; Kodama, Tadayuki; Tanaka, Ichi; Yamada, Toru; Bower, Richard

2006-09-01

We report the discovery of protocluster candidates around high-redshift radio galaxies at z ~ 2.5 on the basis of clear statistical excess of colour-selected galaxies around them seen in the deep near-infrared imaging data obtained with CISCO on the Subaru Telescope. We have observed six targets, all at similar redshifts at z ~ 2.5, and our data reach J = 23.5, H = 22.6 and K = 21.8 (5σ) and cover a 1.6 × 1.6 arcmin2 field centred on each radio galaxy. We apply colour cuts in JHK bands in order to exclusively search for galaxies located at high redshifts, z > 2. Over the magnitude range of 19.5 < K < 21.5, we see a significant excess of red galaxies with J - K > 2.3 by a factor of 2 around the combined radio galaxies fields compared to those found in the general field of the Great Observatories Origins Deep Survey-South (GOODS-S). The excess of galaxies around the radio galaxies fields becomes more than a factor of 3 around 19.5 < K < 20.5 when the two-colour cuts are applied with JHK bands. Such overdensity of the colour-selected galaxies suggests that those fields tend to host high-density regions at high redshifts, although there seems to be the variety of the density of the colour-selected galaxies in each field. In particular, two radio galaxies fields out of the six observed fields show very strong density excess and these are likely to be protoclusters associated with the radio galaxies which would evolve into rich clusters of galaxies dominated by old passively evolving galaxies.

Dual mode operation, highly selective nanohole array-based plasmonic colour filters

NASA Astrophysics Data System (ADS)

Fouladi Mahani, Fatemeh; Mokhtari, Arash; Mehran, Mahdiyeh

2017-09-01

Taking advantage of nanostructured metal films as plasmonic colour filters (PCFs) has been evolved remarkably as an alternative to the conventional technologies of chemical colour filtering. However, most of the proposed PCFs depict a poor colour purity focusing on generating either the additive or subtractive colours. In this paper, we present dual mode operation PCFs employing an opaque aluminium film patterned with sub-wavelength holes. Subtractive colours like cyan, magenta, and yellow are the results of reflection mode of these filters yielding optical efficiencies as high as 70%-80% and full width at half maximum of the stop-bands up to 40-50 nm. The colour selectivity of the transmission mode for the additive colours is also significant due to their enhanced performance through the utilization of a relatively thick aluminium film in contact with a modified dielectric environment. These filters provide a simple design with one-step lithography in addition to compatibility with the conventional CMOS processes. Moreover, they are polarization insensitive due to their symmetric geometry. A complete palette of pure subtractive and additive colours has been realized with potential applications, such as multispectral imaging, CMOS image sensors, displays, and colour printing.

New UBVRI colour distributions in E-type galaxies . I. The data

NASA Astrophysics Data System (ADS)

Idiart, T. P.; Michard, R.; de Freitas Pacheco, J. A.

2002-01-01

New colour distributions have been derived from wide field UBVRI frames for 36 northern bright elliptical galaxies and a few lenticulars. The classical linear representations of colours against log r were derived, with some improvements in the accuracy of the zero point colours and of the gradients. The radial range of significant measurements was enlarged both towards the galaxy center and towards the outskirts of each object. Thus, the ``central colours'', integrated within a radius of 3\\arcsec, and the ``outermost colours'' averaged near the muV =24 surface brightness could also be obtained. Some typical deviations of colour profiles from linearity are described. Colour-colour relations of interest are presented. Very tight correlations are found between the U-V colour and the Mg2 line-index, measured either at the Galaxian center or at the effective radius. Based in part on observations collected at the Observatoire de Haute-Provence. Tables 9-11 plus detailed tables for each object are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/383/30

Innate colour preferences of the Australian native stingless bee Tetragonula carbonaria Sm.

PubMed

Dyer, Adrian G; Boyd-Gerny, Skye; Shrestha, Mani; Lunau, Klaus; Garcia, Jair E; Koethe, Sebastian; Wong, Bob B M

2016-10-01

Innate preferences promote the capacity of pollinators to find flowers. Honeybees and bumblebees have strong preferences for 'blue' stimuli, and flowers of this colour typically present higher nectar rewards. Interestingly, flowers from multiple different locations around the world independently have the same distribution in bee colour space. Currently, however, there is a paucity of data on the innate colour preferences of stingless bees that are often implicated as being key pollinators in many parts of the world. In Australia, the endemic stingless bee Tetragonula carbonaria is widely distributed and known to be an efficient pollinator of both native plants and agricultural crops. In controlled laboratory conditions, we tested the innate colour responses of naïve bees using standard broadband reflectance stimuli representative of common flower colours. Colorimetric analyses considering hymenopteran vision and a hexagon colour space revealed a difference between test colonies, and a significant effect of green contrast and an interaction effect of green contrast with spectral purity on bee choices. We also observed colour preferences for stimuli from the blue and blue-green categorical regions of colour space. Our results are discussed in relation to the similar distribution of flower colours observed from bee pollination around the world.

Dual mode operation, highly selective nanohole array-based plasmonic colour filters.

PubMed

Mahani, Fatemeh Fouladi; Mokhtari, Arash; Mehran, Mahdiyeh

2017-09-20

Taking advantage of nanostructured metal films as plasmonic colour filters (PCFs) has been evolved remarkably as an alternative to the conventional technologies of chemical colour filtering. However, most of the proposed PCFs depict a poor colour purity focusing on generating either the additive or subtractive colours. In this paper, we present dual mode operation PCFs employing an opaque aluminium film patterned with sub-wavelength holes. Subtractive colours like cyan, magenta, and yellow are the results of reflection mode of these filters yielding optical efficiencies as high as 70%-80% and full width at half maximum of the stop-bands up to 40-50 nm. The colour selectivity of the transmission mode for the additive colours is also significant due to their enhanced performance through the utilization of a relatively thick aluminium film in contact with a modified dielectric environment. These filters provide a simple design with one-step lithography in addition to compatibility with the conventional CMOS processes. Moreover, they are polarization insensitive due to their symmetric geometry. A complete palette of pure subtractive and additive colours has been realized with potential applications, such as multispectral imaging, CMOS image sensors, displays, and colour printing.

Using instrumental (CIE and reflectance) measures to predict consumers' acceptance of beef colour.

PubMed

Holman, Benjamin W B; van de Ven, Remy J; Mao, Yanwei; Coombs, Cassius E O; Hopkins, David L

2017-05-01

We aimed to establish colorimetric thresholds based upon the capacity for instrumental measures to predict consumer satisfaction with beef colour. A web-based survey was used to distribute standardised photographs of beef M. longissimus lumborum with known colorimetrics (L*, a*, b*, hue, chroma, ratio of reflectance at 630nm and 580nm, and estimated deoxymyoglobin, oxymyoglobin and metmyoglobin concentrations) for scrutiny. Consumer demographics and perceived importance of colour to beef value were also evaluated. It was found that a* provided the most simple and robust prediction of beef colour acceptability. Beef colour was considered acceptable (with 95% acceptance) when a* values were equal to or above 14.5. Demographic effects on this threshold were negligible, but consumer nationality and gender did contribute to variation in the relative importance of colour to beef value. These results provide future beef colour studies with context to interpret objective colour measures in terms of consumer acceptance and market appeal. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

FReD: the floral reflectance database--a web portal for analyses of flower colour.

PubMed

Arnold, Sarah E J; Faruq, Samia; Savolainen, Vincent; McOwan, Peter W; Chittka, Lars

2010-12-10

Flower colour is of great importance in various fields relating to floral biology and pollinator behaviour. However, subjective human judgements of flower colour may be inaccurate and are irrelevant to the ecology and vision of the flower's pollinators. For precise, detailed information about the colours of flowers, a full reflectance spectrum for the flower of interest should be used rather than relying on such human assessments. The Floral Reflectance Database (FReD) has been developed to make an extensive collection of such data available to researchers. It is freely available at http://www.reflectance.co.uk. The database allows users to download spectral reflectance data for flower species collected from all over the world. These could, for example, be used in modelling interactions between pollinator vision and plant signals, or analyses of flower colours in various habitats. The database contains functions for calculating flower colour loci according to widely-used models of bee colour space, reflectance graphs of the spectra and an option to search for flowers with similar colours in bee colour space. The Floral Reflectance Database is a valuable new tool for researchers interested in the colours of flowers and their association with pollinator colour vision, containing raw spectral reflectance data for a large number of flower species.

Swift UVOT Observations of SN2018apl/ASASSN-18gq

NASA Astrophysics Data System (ADS)

Brown, Peter J.

2018-04-01

SN2018apl/ASASSN-18gq (ATEL #11500) was observed by the Neil Gehrels Swift Observatory beginning 2018-04-03 15:28:06. We measured the magnitudes below from summed images from the first orbit of observations using the Swift Optical Ultraviolet Supernova Archive (SOUSA; Brown et al. 2014).

Ultraviolet spectroscopy of the brightest supergiants in M31 and M33

NASA Technical Reports Server (NTRS)

Humphreys, R. M.; Blaha, C.; Dodorico, S.; Gull, T. R.; Benevenuti, P.

1983-01-01

Ultraviolet spectroscopy from the IUE, in combination with groundbased visual and infrared photometry, are to determine the energy distributions of the luminous blue variables, the Hubble-Sandage variables, in M31 and M33. The observed energy distributions, especially in the ultraviolet, show that these stars are suffering interstellar reddening. When corrected for interstellar extinction, the integrated energy distributions yield the total luminosities and black body temperatures of the stars. The resulting bolometric magnitudes and temperatures confirm that these peculiar stars are indeed very luminous, hot stars. They occupy the same regions of the sub B01 vs. log T sub e diagram as do eta Car, P Cyg and S Dor in our galaxy and the LMC. Many of the Hubble-Sandage variables have excess infrared radiation which is attributed to free-free emission from their extended atmospheres. Rough mass loss estimates from the infrared excess yield rates of 0.00001 M sub annual/yr. The ultraviolet spectra of the H-S variables are also compared with similar spectra of eta Car, P Cyg and S For.

The mid-infrared properties and gas content of active galaxies over large lookback times

NASA Astrophysics Data System (ADS)

Curran, S. J.; Duchesne, S. W.

2018-05-01

Upon an expansion of all of the searches for redshifted H I 21-cm absorption (0.002 1 ≤ z ≤ 5.19), we update recent results regarding the detection of 21-cm in the non-local Universe. Specifically, we confirm that photo-ionization of the gas is the mostly likely cause of the low detection rate at high redshift, in addition to finding that at z ≲ 0.1 there may also be a decrease in the detection rate, which we suggest is due to the dilution of the absorption strength by 21-cm emission. By assuming that associated and intervening absorbers have similar cosmological mass densities, we find evidence that the spin temperature of the gas evolves with redshift, consistent with heating by ultraviolet photons. From the near-infrared (λ = 3.4, 4.6 and 12 μm) colours, we see that radio galaxies become more quasar-like in their activity with increasing redshift. We also find that the non-detection of 21-cm absorption at high redshift is not likely to be due to the selection of gas-poor ellipticals, in addition to a strong correlation between the ionizing photon rate and the [3.4] - [4.6] colour, indicating that the UV photons arise from AGN activity. Like previous studies, we find a correlation between the detection of 21-cm absorption and the [4.6] - [12] colour, which is a tracer of star-forming activity. However, this only applies at the lowest redshifts (z ≲ 0.1), the range considered by the other studies.

Reconstructing the colour palette of the Konstantinos Parthenis' burnt paintings.

PubMed

Antonopoulou-Athera, N; Chatzitheodoridis, E; Terlixi, A; Doulgerides, M; Serafetinides, A A

2018-05-09

This case study focuses on the reconstruction of the colour palette and the possibility of laser cleaning of burnt paintings. The paintings ORPHEUS IN THE UNDERWORLD and CONCORDIA, composed by the Greek artist Konstantinos Parthenis (1878-1967), have been severely damaged by fire. The colour palette of Parthenis is thoroughly investigated for the first time, and to perform this, a multi-analytical spectroscopic approach was employed. Non-destructive in situ analysis was performed on multiple areas of the paintings by portable XRF. SEM-EDS and Raman, supported by reflected visible light optical microscopy, and ultraviolet light microscopy, as well as structural XRD and molecular FTIR were performed for identifying the pigments, the binder and the substrate of the paintings. This work also unveiled new aspects of the painting technique used by the artist, such as the uncommon use of multiple pigments of red hue in the upper paint layers, comparatively with the rest of Parthenis' paintings. Molecular spectroscopic techniques (i.e., Raman and FTIR) were effective in identifying pigments like chrome yellow (crocoite mineral), chrome orange (phoenicochroite mineral) and viridian green (hydrated chromium oxide). The spectroscopic analyses were also essential in the laser cleaning restoration because of the detection of pigments (i.e., lead white, vermilion etc.) prone to phase transformations due to photothermal and/or photochemical effects. Our investigation establishes the basis on the application of non-conventional cleaning methods on damaged paintings, such as laser irradiation, in order to remove the damaged layer and/or the superficial accretions, while preserving the hues of the original painting. Copyright © 2018 Elsevier B.V. All rights reserved.

Skin colour, skin redness and melanin biometric measurements: comparison study between Antera(®) 3D, Mexameter(®) and Colorimeter(®).

PubMed

Matias, Ana Rita; Ferreira, Marta; Costa, Paulo; Neto, Patrícia

2015-08-01

The actual skin colorimeters analyse reflect values from a limited number of broad spectral bands and consequently present limited reproducibility and specificity when measuring skin colour. Here, Antera 3D(®) , a new device which uses reflectance mapping of seven different light wavelengths spanning the entire visible spectrum, has been compared with Mexameter(®) MX-18, an established narrow-band reflectance spectrophotometer and with Colorimeter(®) CL-400, an established tristimulus colorimetric instrument. Thirty volunteers were exposed to a controlled ultra-violet B light. Measurements with Antera 3D(®) , Mexameter(®) MX-18 and Colorimeter(®) CL-400 were done before treatment and after 2, 7 and 14 days. Antera 3D(®) showed to have a better sensitivity and specificity than Mexameter(®) MX-18 regarding the melanin parameter. A similar sensitivity between Antera 3D(®) and Mexameter(®) MX-18 was found for erythema determination and also for the Commission Internationale de l'Eclairage L*, a* and b* parameters between Antera 3D(®) and Colorimeter(®) CL-400. Good correlations were observed for all the parameters analysed. Repeatability of Mexameter(®) MX-18 and Colorimeter(®) CL-400 values were lower than that of Antera 3D(®) for all the parameters analysed. Antera 3D(®) , such as Mexameter(®) MX-18 and Colorimeter(®) CL-400, are robust, sensitive and precise equipment for the skin colour analysis. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Synthetic food colours in saffron solutions, saffron rice and saffron chicken from restaurants in Tehran, Iran.

PubMed

Moradi-Khatoonabadi, Zhila; Amirpour, Mansooreh; AkbariAzam, Maryam

2015-01-01

Saffron solutions, saffron rice and saffron chicken samples were considered for synthetic colours as additives, which are forbidden according to Iranian national standards. Samples were taken from restaurants of three locations and analysed by high-performance liquid chromatography. Of the total 573 samples, 52% were positive for at least one colour. The most prevalent colours were Tartrazine, Quinoline Yellow and Sunset Yellow, with 44%, 9.1% and 8.4% of the samples testing positive for these colours, respectively. Carmoisine and Ponceau were both detected only in 0.5% of the positive samples and found only in saffron solution. In conclusion, synthetic food colours, especially Tartrazine should be regarded as a potential risk in saffron and its related food. Therefore, new attempts for food safety and quality should be undertaken to eliminate the use of these colours in restaurants.

Laser-induced plasmonic colours on metals

NASA Astrophysics Data System (ADS)

Guay, Jean-Michel; Calà Lesina, Antonino; Côté, Guillaume; Charron, Martin; Poitras, Daniel; Ramunno, Lora; Berini, Pierre; Weck, Arnaud

2017-07-01

Plasmonic resonances in metallic nanoparticles have been used since antiquity to colour glasses. The use of metal nanostructures for surface colourization has attracted considerable interest following recent developments in plasmonics. However, current top-down colourization methods are not ideally suited to large-scale industrial applications. Here we use a bottom-up approach where picosecond laser pulses can produce a full palette of non-iridescent colours on silver, gold, copper and aluminium. We demonstrate the process on silver coins weighing up to 5 kg and bearing large topographic variations (~1.5 cm). We find that colours are related to a single parameter, the total accumulated fluence, making the process suitable for high-throughput industrial applications. Statistical image analyses of laser-irradiated surfaces reveal various nanoparticle size distributions. Large-scale finite-difference time-domain computations based on these nanoparticle distributions reproduce trends seen in reflectance measurements, and demonstrate the key role of plasmonic resonances in colour formation.

Laser-induced plasmonic colours on metals

PubMed Central

Guay, Jean-Michel; Calà Lesina, Antonino; Côté, Guillaume; Charron, Martin; Poitras, Daniel; Ramunno, Lora; Berini, Pierre; Weck, Arnaud

2017-01-01

Plasmonic resonances in metallic nanoparticles have been used since antiquity to colour glasses. The use of metal nanostructures for surface colourization has attracted considerable interest following recent developments in plasmonics. However, current top-down colourization methods are not ideally suited to large-scale industrial applications. Here we use a bottom-up approach where picosecond laser pulses can produce a full palette of non-iridescent colours on silver, gold, copper and aluminium. We demonstrate the process on silver coins weighing up to 5 kg and bearing large topographic variations (∼1.5 cm). We find that colours are related to a single parameter, the total accumulated fluence, making the process suitable for high-throughput industrial applications. Statistical image analyses of laser-irradiated surfaces reveal various nanoparticle size distributions. Large-scale finite-difference time-domain computations based on these nanoparticle distributions reproduce trends seen in reflectance measurements, and demonstrate the key role of plasmonic resonances in colour formation. PMID:28719576

Theoretical colours for F and G dwarf stars.

NASA Technical Reports Server (NTRS)

Bell, R. A.

1971-01-01

Synthetic spectra have been computed for F and G dwarf stars, using a number of values of chemical abundance, Doppler broadening velocity, and damping constant. Metal abundances for a number of such stars have been obtained using computed and observed m(sub 1) and 40-52 colors. These abundances are in good agreement with spectroscopically determined ones. The c(sub 1) colors of such stars with exactly known trigonometric parallaxes have been used in order to determine how accurately absolute magnitudes can be predicted from the colors. Generally reasonable agreement can be obtained between observed and predicted absolute magnitudes for certain of these stars. The effects of interstellar reddening on the colors of the models are examined.

Physical constraints on the likelihood of life on exoplanets

NASA Astrophysics Data System (ADS)

Lingam, Manasvi; Loeb, Abraham

2018-04-01

One of the most fundamental questions in exoplanetology is to determine whether a given planet is habitable. We estimate the relative likelihood of a planet's propensity towards habitability by considering key physical characteristics such as the role of temperature on ecological and evolutionary processes, and atmospheric losses via hydrodynamic escape and stellar wind erosion. From our analysis, we demonstrate that Earth-sized exoplanets in the habitable zone around M-dwarfs seemingly display much lower prospects of being habitable relative to Earth, owing to the higher incident ultraviolet fluxes and closer distances to the host star. We illustrate our results by specifically computing the likelihood (of supporting life) for the recently discovered exoplanets, Proxima b and TRAPPIST-1e, which we find to be several orders of magnitude smaller than that of Earth.

Measuring colour rivalry suppression in amblyopia.

PubMed

Hofeldt, T S; Hofeldt, A J

1999-11-01

To determine if the colour rivalry suppression is an index of the visual impairment in amblyopia and if the stereopsis and fusion evaluator (SAFE) instrument is a reliable indicator of the difference in visual input from the two eyes. To test the accuracy of the SAFE instrument for measuring the visual input from the two eyes, colour rivalry suppression was measured in six normal subjects. A test neutral density filter (NDF) was placed before one eye to induce a temporary relative afferent defect and the subject selected the NDF before the fellow eye to neutralise the test NDF. In a non-paediatric private practice, 24 consecutive patients diagnosed with unilateral amblyopia were tested with the SAFE. Of the 24 amblyopes, 14 qualified for the study because they were able to fuse images and had no comorbid disease. The relation between depth of colour rivalry suppression, stereoacuity, and interocular difference in logMAR acuity was analysed. In normal subjects, the SAFE instrument reversed temporary defects of 0.3 to 1. 8 log units to within 0.6 log units. In amblyopes, the NDF to reverse colour rivalry suppression was positively related to interocular difference in logMAR acuity (beta=1.21, p<0.0001), and negatively related to stereoacuity (beta=-0.16, p=0.019). The interocular difference in logMAR acuity was negatively related to stereoacuity (beta=-0.13, p=0.009). Colour rivalry suppression as measured with the SAFE was found to agree closely with the degree of visual acuity impairment in non-paediatric patients with amblyopia.

The Lockheed OSO-8 program. Task 2: Analysis of data from the high resolution ultraviolet spectrometer experiment. [carbon 4 and silicon 4 line and emission spectra from solar flares

NASA Technical Reports Server (NTRS)

Bruner, E. C., Jr.

1980-01-01

The complete set of C 4 time sequences generated by the University of Colorado high resolution ultraviolet spectrometer experiment on OSO-8 were examined in a comprehensive and systematic fashion. As a result a new limit is placed on the acoustic flux passing through the transition zone of the Sun's atmosphere. It is found to be three orders of magnitude too small to heat the corona, and is consistent with zero. In collaborative efforts, the properties of transient C 4 brightenings were examined in considerable detail.

VizieR Online Data Catalog: Ultraviolet Excess Galaxies (Mitchell+ 1982)

NASA Astrophysics Data System (ADS)

Mitchell, K. J.; Brotzman, L. E.; Warnock, A.; Usher, P. D.

2015-05-01

The catalog contains a list of 412 faint galaxies selected for their apparent ultraviolet excess. The galaxies were selected from a 3-color (UBV) plate taken with the Palomar 48-inch Schmidt telescope. The 14-inch-square plates cover an area of 30 square degrees centered on Kapteyn Selected Area 28. The catalog includes running numbers, coordinates, color codes, magnitude codes, morphologies, diameters, and notes. The catalogued galaxies were selected by eye from the Palomar Schmidt 3-color (UBV) plate PS24771, centered on Kapteyn Selexted Area 28 and taken by Usher under conditions of good seeing and transparency. (1 data file).

Improved colour matching technique for fused nighttime imagery with daytime colours

NASA Astrophysics Data System (ADS)

Hogervorst, Maarten A.; Toet, Alexander

2016-10-01

Previously, we presented a method for applying daytime colours to fused nighttime (e.g., intensified and LWIR) imagery (Toet and Hogervorst, Opt.Eng. 51(1), 2012). Our colour mapping not only imparts a natural daylight appearance to multiband nighttime images but also enhances the contrast and visibility of otherwise obscured details. As a result, this colourizing method leads to increased ease of interpretation, better discrimination and identification of materials, faster reaction times and ultimately improved situational awareness (Toet e.a., Opt.Eng.53(4), 2014). A crucial step in this colouring process is the choice of a suitable colour mapping scheme. When daytime colour images and multiband sensor images of the same scene are available the colour mapping can be derived from matching image samples (i.e., by relating colour values to sensor signal intensities). When no exact matching reference images are available the colour transformation can be derived from the first-order statistical properties of the reference image and the multiband sensor image (Toet, Info. Fus. 4(3), 2003). In the current study we investigated new colour fusion schemes that combine the advantages of the both methods, using the correspondence between multiband sensor values and daytime colours (1st method) in a smooth transformation (2nd method). We designed and evaluated three new fusion schemes that focus on: i) a closer match with the daytime luminances, ii) improved saliency of hot targets and iii) improved discriminability of materials

From spectral information to animal colour vision: experiments and concepts.

PubMed

Kelber, Almut; Osorio, Daniel

2010-06-07

Many animals use the spectral distribution of light to guide behaviour, but whether they have colour vision has been debated for over a century. Our strong subjective experience of colour and the fact that human vision is the paradigm for colour science inevitably raises the question of how we compare with other species. This article outlines four grades of 'colour vision' that can be related to the behavioural uses of spectral information, and perhaps to the underlying mechanisms. In the first, even without an (image-forming) eye, simple organisms can compare photoreceptor signals to locate a desired light environment. At the next grade, chromatic mechanisms along with spatial vision guide innate preferences for objects such as food or mates; this is sometimes described as wavelength-specific behaviour. Here, we compare the capabilities of di- and trichromatic vision, and ask why some animals have more than three spectral types of receptors. Behaviours guided by innate preferences are then distinguished from a grade that allows learning, in part because the ability to learn an arbitrary colour is evidence for a neural representation of colour. The fourth grade concerns colour appearance rather than colour difference: for instance, the distinction between hue and saturation, and colour categorization. These higher-level phenomena are essential to human colour perception but poorly known in animals, and we suggest how they can be studied. Finally, we observe that awareness of colour and colour qualia cannot be easily tested in animals.

Effect of location in the canopy on the colour development of three apple cultivars during growth.

PubMed

Unuk, Tatjana; Tijskens, L M M Pol; Germšek, Blaž; Zadravec, Peter; Vogrin, Andrej; Hribar, Janez; Simčič, Marjan; Tojnko, Stanislav

2012-09-01

Homogeneity in appearance is one of the quality aspects asked for in the supply chain. Decreasing the biological variation in batches of harvested apples (cultivars Braeburn, Fuji and Gala) becomes increasingly important. Skin colour is one of the aspects that determine both optimal harvest and stage of development. Skin colour is affected by location in the canopy. The rules of development of biological variation are now established and will be used on skin colour data. The Minolta colour aspects a*, b* and L* measured before commercial harvest change in a sigmoidal fashion and can be analysed including the biological variation, with a logistic model in indexed nonlinear regression, obtaining explained parts of above 90%. The mechanism of colour change is not affected by state of development or location in the canopy. The location in the canopy affects the intensity of both red and green colouring compounds. The variation in colouration is not affected by the location in the canopy. The red-coloured apple cultivar (Gala) depends more on the location in the canopy than the less-coloured cultivars (Fuji and Braeburn). The colour development in Fuji apples is considerably slower, with a much larger variation in stage of development. The location in the canopy affects all aspects of biological variation (biological shift factor and asymptotic starting level of colouration) for all three colour aspects L*, a* and b*, but only the mean value, not the standard deviation. The biological shift factors per colour aspects are linearly related. Once induced, variation remains constant during development. Copyright © 2012 Society of Chemical Industry.

Object Interference in Children's Colour and Position Naming: Lexical Interference or Task-Set Competition?

ERIC Educational Resources Information Center

La Heij, Wido; Boelens, Harrie; Kuipers, Jan-Rouke

2010-01-01

Cascade models of word production assume that during lexical access all activated concepts activate their names. In line with this view, it has been shown that naming an object's colour is facilitated when colour name and object name are phonologically related (e.g., "blue" and "blouse"). Prevor and Diamond's (2005) recent observation that…

Lightness and Hue Perception: The Bezold-Brucke Effect and Colour Basic Categories

ERIC Educational Resources Information Center

Lillo, Julio; Aguado, Luis; Moreira, Humberto; Davies, Ian

2004-01-01

Using surface colours as stimuli, the present research was aimed at the two following goals: (1) To determine the chromatic angles related to categorical effects type B-B (Bezold-Brucke). (2) To determine the colourimetric characteristics compatible with each Spanish colour basic category. To get these goals the full set of tiles included in the…

Formation of automatic letter-colour associations in non-synaesthetes through likelihood manipulation of letter-colour pairings.

PubMed

Kusnir, Flor; Thut, Gregor

2012-12-01

Grapheme-colour synaesthesia is a well-characterized phenomenon in which achromatic letters and/or digits automatically and systematically trigger specific colour sensations. Models of its underlying mechanisms diverge on a central question: whether triggered sensations reflect (1) an overdeveloped capacity in normal cross-modal processing (i.e., sharing characteristics with the general population), or rather (2) qualitatively deviant processing (i.e., unique to a few individuals). To test to what extent synaesthesia-like (automatic) letter-colour associations may be learned by non-synaesthetes into adulthood, implied by (1), we developed a learning paradigm that aimed to implicitly train such associations via a visual search task that employed statistical probability learning of specific letter-colour pairs. In contrast to previous synaesthesia-training studies (Cohen Kadosh, Henik, Catena, Walsh, & Fuentes, 2009; Meier & Rothen, 2009), here all participants were naïve as to the end-goal of the experiment (i.e., the formation of letter-colour associations), mimicking the learning conditions of acquired grapheme-colour synaesthesia (Hancock, 2006; Witthoft & Winawer, 2006). In two experiments, we found evidence for significant binding of colours to letters by non-synaesthetes. These newly-formed associations showed synaesthesia-like characteristics, because they correlated in strength with performance on individual synaesthetic Stroop-tasks (experiment 1), and because interference between the learned (associated) colour and the real colour during letter processing depended on their relative positions in colour space (opponent vs. non-opponent colours, experiment 2) suggesting automatic formation on a perceptual rather than conceptual level, analogous to synaesthesia. Although not evoking conscious colour percepts, these learned, synaesthesia-like associations in non-synaesthetes support that common mechanisms may underlie letter-colour associations in synaesthetes and non-synaesthetes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours. I. Grids of 3D corrections in the UBVRI, 2MASS, HIPPARCOS, Gaia, and SDSS systems

NASA Astrophysics Data System (ADS)

Bonifacio, P.; Caffau, E.; Ludwig, H.-G.; Steffen, M.; Castelli, F.; Gallagher, A. J.; Kučinskas, A.; Prakapavičius, D.; Cayrel, R.; Freytag, B.; Plez, B.; Homeier, D.

2018-03-01

Context. The atmospheres of cool stars are temporally and spatially inhomogeneous due to the effects of convection. The influence of this inhomogeneity, referred to as granulation, on colours has never been investigated over a large range of effective temperatures and gravities. Aim. We aim to study, in a quantitative way, the impact of granulation on colours. Methods: We use the CIFIST (Cosmological Impact of the FIrst Stars) grid of CO5BOLD (COnservative COde for the COmputation of COmpressible COnvection in a BOx of L Dimensions, L = 2, 3) hydrodynamical models to compute emerging fluxes. These in turn are used to compute theoretical colours in the UBV RI, 2MASS, HIPPARCOS, Gaia and SDSS systems. Every CO5BOLD model has a corresponding one dimensional (1D) plane-parallel LHD (Lagrangian HydroDynamics) model computed for the same atmospheric parameters, which we used to define a "3D correction" that can be applied to colours computed from fluxes computed from any 1D model atmosphere code. As an example, we illustrate these corrections applied to colours computed from ATLAS models. Results: The 3D corrections on colours are generally small, of the order of a few hundredths of a magnitude, yet they are far from negligible. We find that ignoring granulation effects can lead to underestimation of Teff by up to 200 K and overestimation of gravity by up to 0.5 dex, when using colours as diagnostics. We have identified a major shortcoming in how scattering is treated in the current version of the CIFIST grid, which could lead to offsets of the order 0.01 mag, especially for colours involving blue and UV bands. We have investigated the Gaia and HIPPARCOS photometric systems and found that the (G - Hp), (BP - RP) diagram is immune to the effects of granulation. In addition, we point to the potential of the RVS photometry as a metallicity diagnostic. Conclusions: Our investigation shows that the effects of granulation should not be neglected if one wants to use colours as diagnostics of the stellar parameters of F, G, K stars. A limitation is that scattering is treated as true absorption in our current computations, thus our 3D corrections are likely an upper limit to the true effect. We are already computing the next generation of the CIFIST grid, using an approximate treatment of scattering. The appendix tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A68

Diurnal adjustment in ultraviolet sunscreen protection is widespread among higher plants.

PubMed

Barnes, Paul W; Flint, Stephan D; Tobler, Mark A; Ryel, Ronald J

2016-05-01

The accumulation of ultraviolet (UV)-absorbing compounds (flavonoids and related phenylpropanoids) in the epidermis of higher plants reduces the penetration of solar UV radiation to underlying tissues and is a primary mechanism of acclimation to changing UV conditions resulting from ozone depletion and climate change. Previously we reported that several herbaceous plant species were capable of rapid, diurnal adjustments in epidermal UV transmittance (T UV), but how widespread this phenomenon is among plants has been unknown. In the present study, we tested the generality of this response by screening 37 species of various cultivated and wild plants growing in four locations spanning a gradient of ambient solar UV and climate (Hawaii, Utah, Idaho and Louisiana). Non-destructive measurements of adaxial T UV indicated that statistically significant midday decreases in T UV occurred in 49 % of the species tested, including both herbaceous and woody growth forms, and there was substantial interspecific variation in the magnitude of these changes. In general, plants in Louisiana exhibited larger diurnal changes in T UV than those in the other locations. Moreover, across all taxa, the magnitude of these changes was positively correlated with minimum daily air temperatures but not daily UV irradiances. Results indicate that diurnal changes in UV shielding are widespread among higher plants, vary both within and among species and tend to be greatest in herbaceous plants growing in warm environments. These findings suggest that plant species differ in their UV protection "strategies" though the functional and ecological significance of this variation in UV sunscreen protection remains unclear at present.

On the roles of colour and scent in a specialized floral mimicry system

PubMed Central

Vereecken, Nicolas J.; Schiestl, Florian P.

2009-01-01

Background and Aims Sexually deceptive orchids achieve cross-pollination by mimicking the mating signals of female insects, generally hymenopterans. This pollination mechanism is often highly specific as it is based primarily on the mimicry of mating signals, especially the female sex pheromones of the targeted pollinator. Like many deceptive orchids, the Mediterranean species Ophrys arachnitiformis shows high levels of floral trait variation, especially in the colour of the perianth, which is either green or white/pinkinsh within populations. The adaptive significance of perianth colour polymorphism and its influence on pollinator visitation rates in sexually deceptive orchids remain obscure. Methods The relative importance of floral scent versus perianth colour in pollinator attraction in this orchid pollinator mimicry system was evaluated by performing floral scent analyses by gas chromatography-mass spectrometry (GC-MS) and behavioural bioassays with the pollinators under natural conditions were performed. Key Results The relative and absolute amounts of behaviourally active compounds are identical in the two colour morphs of O. arachnitiformis. Neither presence/absence nor the colour of the perianth (green versus white) influence attractiveness of the flowers to Colletes cunicularius males, the main pollinator of O. arachnitiformis. Conclusion Chemical signals alone can mediate the interactions in highly specialized mimicry systems. Floral colour polymorphism in O. arachnitiformis is not subjected to selection imposed by C. cunicularius males, and an interplay between different non-adaptive processes may be responsible for the maintenance of floral colour polymorphism both within and among populations. PMID:19692390

On the roles of colour and scent in a specialized floral mimicry system.

PubMed

Vereecken, Nicolas J; Schiestl, Florian P

2009-11-01

Sexually deceptive orchids achieve cross-pollination by mimicking the mating signals of female insects, generally hymenopterans. This pollination mechanism is often highly specific as it is based primarily on the mimicry of mating signals, especially the female sex pheromones of the targeted pollinator. Like many deceptive orchids, the Mediterranean species Ophrys arachnitiformis shows high levels of floral trait variation, especially in the colour of the perianth, which is either green or white/pinkinsh within populations. The adaptive significance of perianth colour polymorphism and its influence on pollinator visitation rates in sexually deceptive orchids remain obscure. The relative importance of floral scent versus perianth colour in pollinator attraction in this orchid pollinator mimicry system was evaluated by performing floral scent analyses by gas chromatography-mass spectrometry (GC-MS) and behavioural bioassays with the pollinators under natural conditions were performed. The relative and absolute amounts of behaviourally active compounds are identical in the two colour morphs of O. arachnitiformis. Neither presence/absence nor the colour of the perianth (green versus white) influence attractiveness of the flowers to Colletes cunicularius males, the main pollinator of O. arachnitiformis. Chemical signals alone can mediate the interactions in highly specialized mimicry systems. Floral colour polymorphism in O. arachnitiformis is not subjected to selection imposed by C. cunicularius males, and an interplay between different non-adaptive processes may be responsible for the maintenance of floral colour polymorphism both within and among populations.

Viability of Cladosporium herbarum spores under 157 nm laser and vacuum ultraviolet irradiation, low temperature (10 K) and vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarantopoulou, E., E-mail: esarant@eie.gr; Stefi, A.; Kollia, Z.

Ultraviolet photons can damage microorganisms, which rarely survive prolonged irradiation. In addition to the need for intact DNA, cell viability is directly linked to the functionality of the cell wall and membrane. In this work, Cladosporium herbarum spore monolayers exhibit high viability (7%) when exposed to 157 nm laser irradiation (412 kJm⁻²) or vacuum-ultraviolet irradiation (110–180 nm) under standard pressure and temperature in a nitrogen atmosphere. Spore viability can be determined by atomic-force microscopy, nano-indentation, mass, μ-Raman and attenuated reflectance Fourier-transform far-infrared spectroscopies and DNA electrophoresis. Vacuum ultraviolet photons cause molecular damage to the cell wall, but radiation resistance inmore » spores arises from the activation of a photon-triggered signaling reaction, expressed via the exudation of intracellular substances, which, in combination with the low penetration depth of vacuum-ultraviolet photons, shields DNA from radiation. Resistance to phototoxicity under standard conditions was assessed, as was resistance to additional environmental stresses, including exposure in a vacuum, under different rates of change of pressure during pumping time and low (10 K) temperatures. Vacuum conditions were far more destructive to spores than vacuum-ultraviolet irradiation, and UV-B photons were two orders of magnitude more damaging than vacuum-ultraviolet photons. The viability of irradiated spores was also enhanced at 10 K. This work, in addition to contributing to the photonic control of the viability of microorganisms exposed under extreme conditions, including decontamination of biological warfare agents, outlines the basis for identifying bio-signaling in vivo using physical methodologies.« less

Reconstructive colour X-ray diffraction imaging--a novel TEDDI imaging method.

PubMed

Lazzari, Olivier; Jacques, Simon; Sochi, Taha; Barnes, Paul

2009-09-01

Tomographic Energy-Dispersive Diffraction Imaging (TEDDI) enables a unique non-destructive mapping of the interior of bulk objects, exploiting the full range of X-ray signals (diffraction, fluorescence, scattering, background) recorded. By analogy to optical imaging, a wide variety of features (structure, composition, orientation, strain) dispersed in X-ray wavelengths can be extracted and colour-coded to aid interpretation. The ultimate aim of this approach is to realise real-time high-definition colour X-ray diffraction imaging, on the timescales of seconds, so that one will be able to 'look inside' optically opaque apparatus and unravel the space/time-evolution of the materials chemistry taking place. This will impact strongly on many fields of science but there are currently two barriers to this goal: speed of data acquisition (a 2D scan currently takes minutes to hours) and loss of image definition through spatial distortion of the X-ray sampling volume. Here we present a data-collection scenario and reconstruction routine which overcomes the latter barrier and which has been successfully applied to a phantom test object and to real materials systems such as a carbonating cement block. These procedures are immediately transferable to the promising technology of multi-energy-dispersive-detector-arrays which are planned to deliver the other breakthrough, that of one-two orders of magnitude improvement in data acquisition rates, that will be needed to realise real-time high-definition colour X-ray diffraction imaging.

The UV and X-ray activity of the M dwarfs within 10 pc of the Sun

NASA Astrophysics Data System (ADS)

Stelzer, B.; Marino, A.; Micela, G.; López-Santiago, J.; Liefke, C.

2013-05-01

M dwarfs are the most numerous stars in the Galaxy. They are characterized by strong magnetic activity. The ensuing high-energy emission is crucial for the evolution of their planets and the eventual presence of life on them. We systematically study the X-ray and ultraviolet emission of a subsample of M dwarfs from a recent proper-motion survey, selecting all M dwarfs within 10 pc to obtain a nearly volume-limited sample (˜90 per cent completeness). Archival ROSAT, XMM-Newton and GALEX data are combined with published spectroscopic studies of Hα emission and rotation to obtain a broad picture of stellar activity on M dwarfs. We make use of synthetic model spectra to determine the relative contributions of photospheric and chromospheric emission to the ultraviolet flux. We also analyse the same diagnostics for a comparison sample of young M dwarfs in the TW Hya association (˜10 Myr). We find that generally the emission in the GALEX bands is dominated by the chromosphere but the photospheric component is not negligible in early-M field dwarfs. The surface fluxes for the Hα, near-ultraviolet, far-ultraviolet and X-ray emission are connected via a power-law dependence. We present here for the first time such flux-flux relations involving broad-band ultraviolet emission for M dwarfs. Activity indices are defined as flux ratio between the activity diagnostic and the bolometric flux of the star in analogy to the Ca IIR'HK index. For given spectral type, these indices display a spread of 2-3 dex which is largest for M4 stars. Strikingly, at mid-M spectral types, the spread of rotation rates is also at its highest level. The mean activity index for fast rotators, likely representing the saturation level, decreases from X-rays over the FUV to the NUV band and Hα, i.e. the fractional radiation output increases with atmospheric height. The comparison to the ultraviolet and X-ray properties of TW Hya members shows a drop of nearly three orders of magnitude for the luminosity in these bands between ˜10 Myr and few Gyr age. A few young field dwarfs (<1 Gyr) in the 10-pc sample bridge the gap indicating that the drop in magnetic activity with age is a continuous process. The slope of the age decay is steeper for the X-ray than for the UV luminosity.

Male courtship preferences demonstrate discrimination against allopatric colour morphs in a cichlid fish

PubMed Central

Zoppoth, P; Koblmüller, S; Sefc, K M

2013-01-01

Whether premating isolation is achieved by male-specific, female-specific or sex-independent assortative preferences often depends on the underlying evolutionary processes. Here we test mate preferences of males presented with females of different allopatric colour variants of the cichlid fish Tropheus sp., a Lake Tanganyika endemic with rich geographical colour pattern variation, in which the strength of sexual isolation varies between populations. We conducted two-way mate choice experiments to compare behaviour of males of a red-bodied morph (population Moliro) towards females from their own population with behaviour towards females from four allopatric populations at different stages of phylogenetic and phenotypic divergence. Males courted same-population females significantly more intensely than females of other populations, and reduced their heteromorphic courtship efforts both with increasing genetic and increasing phenotypic distinctness of the females. In particular, females of a closely related red-bodied population received significantly more courtship than either genetically distinct, similarly coloured females (‘Kirschfleck’ morph) or genetically related, differently coloured females (‘yellow-blotch’ morph), both of which were courted similarly. Genetically and phenotypically distinct females (Tropheus polli) were not courted at all. Consistent with previous female-choice experiments, female courtship activity also decreased with increasing genetic distance from the males’ population. Given successful experimental and natural introgression between colour morphs and the pervasive allopatry of related variants, we consider it unlikely that assortative preferences of both sexes were driven by direct selection during periods of secondary contact or, in turn, drove colour pattern differentiation in allopatry. Rather, we suggest that sexual isolation evolved as by-product of allopatric divergence. PMID:23405907

Imagery, colour and illness: a review.

PubMed

Carruthers, Helen R

2011-09-01

This paper reviews research on the role of colour and imagery in relation to illness and examines how this might improve communication between the sufferer and those treating or caring for them. It describes a method by which colour can be related to situations such as an individual's mood and how this might be used to predict response to treatment. Furthermore, it provides evidence that documenting the imagery of an illness might give insight into the patients' fears and concerns about their condition as well as helping non-sufferers to understand what they are going through.

Dissecting the mechanism of Solanum lycopersicum and Solanum chilense flower colour formation.

PubMed

Gao, M; Qu, H; Gao, L; Chen, L; Sebastian, R S J; Zhao, L

2015-01-01

Flowers are the defining feature of angiosperms, and function as indispensable organs for sexual reproduction. Flower colour typically plays an important role in attracting pollinators, and can show considerable variation, even between closely related species. For example, domesticated tomato (S. lycopersicum) has orange/yellow flowers, while the wild relative S. chilense (accession LA2405) has bright yellow flowers. In this study, the mechanism of flower colour formation in these two species was compared by evaluating the accumulation of carotenoids, assessing the expression genes related to carotenoid biosynthetic pathways and observing chromoplast ultrastructure. In S. chilense petals, genes associated with the lutein branch of the carotenoid biosynthetic pathway, phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), lycopene β-cyclase (LCY-B), β-ring hydroxylase (CRTR-B) and ε-ring hydroxylase (CRTR-E), were highly expressed, and this was correlated with high levels of lutein accumulation. In contrast, PDS, ZDS and CYC-B from the neoxanthin biosynthetic branch were highly expressed in S. lycopersicum anthers, leading to increased β-carotene accumulation and hence an orange/yellow colour. Changes in the size, amount and electron density of plastoglobules in chromoplasts provided further evidence of carotenoid accumulation and flower colour formation. Taken together, these results reveal the biochemical basis of differences in carotenoid pigment accumulation and colour between petals and anthers in tomato. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

(Re)-wiring a brain with light: Clinical and visual processing findings after application of specific coloured glasses in patients with symptoms of a visual processing disorder (CVPD): Challenge of a possible new perspective?

PubMed

Friederichs, Edgar; Wahl, Siegfried

2017-08-01

The present investigation examined whether changes of electrophysiological late event related potential pattern could be used to reflect clinical changes from therapeutic intervention with coloured glasses in a group of patients with symptoms of central visual processing disorder. Subjects consisted of 13 patients with average age 16years (range 6-51years) with attention problems and learning disability, respectively. These patients were provided with specified coloured glasses which were required to be used during day time. Results indicated that specified coloured glasses significantly improved attention performance. Furthermore electrophysiological parameters revealed a significant change in the late event related potential distribution pattern (latency, amplitudes). This reflects a synchronization of together firing wired neural assemblies responsible for visual processing, suggesting an accelerated neuromaturation process when using coloured glasses. Our results suggest that the visual event related potentials measures are sensitive to changes in clinical development of patients with deficits of visual processing wearing appropriate coloured glasses. It will be discussed whether such a device might be useful for a clinical improvement of distraction symptoms caused by visual processing deficits. A model is presented explaining these effects by inducing the respiratory chain of the mitochondria such increasing the low energy levels of ATP of our patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Site-directed mutagenesis of firefly luciferase: implication of conserved residue(s) in bioluminescence emission spectra among firefly luciferases.

PubMed

Tafreshi, Narges Kh; Sadeghizadeh, Majid; Emamzadeh, Rahman; Ranjbar, Bijan; Naderi-Manesh, Hossein; Hosseinkhani, Saman

2008-05-15

The bioluminescence colours of firefly luciferases are determined by assay conditions and luciferase structure. Owing to red light having lower energy than green light and being less absorbed by biological tissues, red-emitting luciferases have been considered as useful reporters in imaging technology. A set of red-emitting mutants of Lampyris turkestanicus (Iranian firefly) luciferase has been made by site-directed mutagenesis. Among different beetle luciferases, those from Phrixothrix (railroad worm) emit either green or red bioluminescence colours naturally. By substitution of three specific amino acids using site-specific mutagenesis in a green-emitting luciferase (from L. turkestanicus), the colour of emitted light was changed to red concomitant with decreasing decay rate. Different specific mutations (H245N, S284T and H431Y) led to changes in the bioluminescence colour. Meanwhile, the luciferase reaction took place with relative retention of its basic kinetic properties such as K(m) and relative activity. Structural comparison of the native and mutant luciferases using intrinsic fluorescence, far-UV CD spectra and homology modelling revealed a significant conformational change in mutant forms. A change in the colour of emitted light indicates the critical role of these conserved residues in bioluminescence colour determination among firefly luciferases. Relatively high specific activity and emission of red light might make these mutants suitable as reporters for the study of gene expression and bioluminescence imaging.

FReD: The Floral Reflectance Database — A Web Portal for Analyses of Flower Colour

PubMed Central

Savolainen, Vincent; McOwan, Peter W.; Chittka, Lars

2010-01-01

Background Flower colour is of great importance in various fields relating to floral biology and pollinator behaviour. However, subjective human judgements of flower colour may be inaccurate and are irrelevant to the ecology and vision of the flower's pollinators. For precise, detailed information about the colours of flowers, a full reflectance spectrum for the flower of interest should be used rather than relying on such human assessments. Methodology/Principal Findings The Floral Reflectance Database (FReD) has been developed to make an extensive collection of such data available to researchers. It is freely available at http://www.reflectance.co.uk. The database allows users to download spectral reflectance data for flower species collected from all over the world. These could, for example, be used in modelling interactions between pollinator vision and plant signals, or analyses of flower colours in various habitats. The database contains functions for calculating flower colour loci according to widely-used models of bee colour space, reflectance graphs of the spectra and an option to search for flowers with similar colours in bee colour space. Conclusions/Significance The Floral Reflectance Database is a valuable new tool for researchers interested in the colours of flowers and their association with pollinator colour vision, containing raw spectral reflectance data for a large number of flower species. PMID:21170326

Camouflage through colour change: mechanisms, adaptive value and ecological significance

PubMed Central

Flores, Augusto A. V.

2017-01-01

Animals from a wide range of taxonomic groups are capable of colour change, of which camouflage is one of the main functions. A considerable amount of past work on this subject has investigated species capable of extremely rapid colour change (in seconds). However, relatively slow colour change (over hours, days, weeks and months), as well as changes arising via developmental plasticity are probably more common than rapid changes, yet less studied. We discuss three key areas of colour change and camouflage. First, we review the mechanisms underpinning colour change and developmental plasticity for camouflage, including cellular processes, visual feedback, hormonal control and dietary factors. Second, we discuss the adaptive value of colour change for camouflage, including the use of different camouflage types. Third, we discuss the evolutionary–ecological implications of colour change for concealment, including what it can tell us about intraspecific colour diversity, morph-specific strategies, and matching to different environments and microhabitats. Throughout, we discuss key unresolved questions and present directions for future work, and highlight how colour change facilitates camouflage among habitats and arises when animals are faced with environmental changes occurring over a range of spatial and temporal scales. This article is part of the themed issue ‘Animal coloration: production, perception, function and application’. PMID:28533459

Minimum Colour Differences Required To Recognise Small Objects On A Colour CRT

NASA Astrophysics Data System (ADS)

Phillips, Peter L.

1985-05-01

Data is required to assist in the assessment, evaluation and optimisation of colour and other displays for both military and general use. A general aim is to develop a mathematical technique to aid optimisation and reduce the amount of expensive hardware development and trials necessary when introducing new displays. The present standards and methods available for evaluating colour differences are known not to apply to the perception of typical objects on a display. Data is required for irregular objects viewed at small angular subtense ((1°) and relating the recognition of form rather than colour matching. Therefore laboratory experiments have been carried out using a computer controlled CRT to measure the threshold colour difference that an observer requires between object and background so that he can discriminate a variety of similar objects. Measurements are included for a variety of background and object colourings. The results are presented in the CIE colorimetric system similar to current standards used by the display engineer. Apart from the characteristic small field tritanopia, the results show that larger colour differences are required for object recognition than those assumed from conventional colour discrimination data. A simple relationship to account for object size and background colour is suggested to aid visual performance assessments and modelling.

Personality predicts the vibrancy of colour imagery: The case of synaesthesia.

PubMed

Hossain, Shyla R; Simner, Julia; Ipser, Alberta

2017-07-01

In this study we show that personality traits predict the physical qualities of mentally generated colours, using the case of synaesthesia. Developmental grapheme-colour synaesthetes have the automatic lifelong association of colours paired to letters or digits. Although these colours are internal mental constructs, they can be measured along physical dimensions such as saturation and luminance. The personality of synaesthetes can also be quantified using self-report questionnaires relating, for example, to the five major traits of Conscientiousness, Extraversion, Agreeableness, Neuroticism, and Openness to Experience. In this paper, we bring together both types of quality by examining whether the personality of individual synaesthetes predicts their synaesthetic colours. Twenty grapheme-colour synaesthetes were tested with the Big Five Inventory (BFI) personality questionnaire. Their synaesthesia was also tested in terms of consistency and average colour saturation and luminance. Two major results were found: although personality did not influence the overall robustness (i.e., consistency) of synaesthesia, it predicted the nature of synaesthetes' colours: the trait of Openness was positively correlated with the saturation of synaesthetic colours. Our study provides evidence that personality and internal perception are intertwined, and suggests future avenues of research for investigating the associations between the two. Copyright © 2017 Elsevier Ltd. All rights reserved.

Camouflage through colour change: mechanisms, adaptive value and ecological significance.

PubMed

Duarte, Rafael C; Flores, Augusto A V; Stevens, Martin

2017-07-05

Animals from a wide range of taxonomic groups are capable of colour change, of which camouflage is one of the main functions. A considerable amount of past work on this subject has investigated species capable of extremely rapid colour change (in seconds). However, relatively slow colour change (over hours, days, weeks and months), as well as changes arising via developmental plasticity are probably more common than rapid changes, yet less studied. We discuss three key areas of colour change and camouflage. First, we review the mechanisms underpinning colour change and developmental plasticity for camouflage, including cellular processes, visual feedback, hormonal control and dietary factors. Second, we discuss the adaptive value of colour change for camouflage, including the use of different camouflage types. Third, we discuss the evolutionary-ecological implications of colour change for concealment, including what it can tell us about intraspecific colour diversity, morph-specific strategies, and matching to different environments and microhabitats. Throughout, we discuss key unresolved questions and present directions for future work, and highlight how colour change facilitates camouflage among habitats and arises when animals are faced with environmental changes occurring over a range of spatial and temporal scales.This article is part of the themed issue 'Animal coloration: production, perception, function and application'. © 2017 The Authors.

Behavioural evidence for colour vision in an elasmobranch.

PubMed

Van-Eyk, Sarah M; Siebeck, Ulrike E; Champ, Connor M; Marshall, Justin; Hart, Nathan S

2011-12-15

Little is known about the sensory abilities of elasmobranchs (sharks, skates and rays) compared with other fishes. Despite their role as apex predators in most marine and some freshwater habitats, interspecific variations in visual function are especially poorly studied. Of particular interest is whether they possess colour vision and, if so, the role(s) that colour may play in elasmobranch visual ecology. The recent discovery of three spectrally distinct cone types in three different species of ray suggests that at least some elasmobranchs have the potential for functional trichromatic colour vision. However, in order to confirm that these species possess colour vision, behavioural experiments are required. Here, we present evidence for the presence of colour vision in the giant shovelnose ray (Glaucostegus typus) through the use of a series of behavioural experiments based on visual discrimination tasks. Our results show that these rays are capable of discriminating coloured reward stimuli from other coloured (unrewarded) distracter stimuli of variable brightness with a success rate significantly different from chance. This study represents the first behavioural evidence for colour vision in any elasmobranch, using a paradigm that incorporates extensive controls for relative stimulus brightness. The ability to discriminate colours may have a strong selective advantage for animals living in an aquatic ecosystem, such as rays, as a means of filtering out surface-wave-induced flicker.

Self-reported skin colour and erythemal sensitivity vs. objectively measured constitutive skin colour in an African population with predominantly dark skin.

PubMed

Wright, Caradee Y; Wilkes, Marcus; du Plessis, Johan L; Reeder, Anthony I

2015-11-01

Skin colour is an important factor in skin-related diseases. Accurate determination of skin colour is important for disease prevention and supporting healthy sun behaviour, yet such data are lacking for dark skin types. Self-perceived, natural skin colour and sun-skin reaction were compared with objectively measured skin colour among an African population with predominantly dark skin. Unexposed skin of 556 adults (70.1% Black) was measured with a reflectance spectrophotometer to calculate an individual typology angle (°ITA). Participants reported self-perceived skin colour and erythemal sensitivity. There was a strong, positive monotonic correlation between self-reported and measured skin colour (Spearman ρ = 0.6438, P < 0.001), but only a weak correlation between self-reported erythemal sensitivity and measured skin colour (Spearman ρ = 0.2713, P < 0.001). Self-report biases in underestimation and overestimation of skin colour were evident. Many participants with 'dark brown' and 'black' skin had difficulty in classifying erythemal sensitivity. In Africa, self-reported skin colour could potentially be used in lieu of spectrophotometer measurements, but options for questions on sunburn and tanning require suitable adjustment. Our study provides evidence of range in °ITA values among residents in Africa and reinforces previous results that self-report may be reliable for determining skin colour, but not erythemal sensitivity, for dark skin individuals. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Signal content of red facial coloration in female mandrills (Mandrillus sphinx).

PubMed

Setchell, Joanna M; Wickings, E Jean; Knapp, Leslie A

2006-09-22

Studies of secondary sexual ornamentation and its maintenance by sexual selection tend to focus on males; however, females may also possess showy ornaments. For example, female mandrills possess facial coloration that ranges from black to bright pink. We used fortnightly photographs of 52 semi-free-ranging females aged above 3years over 19 months to evaluate whether colour conveys information concerning female competitive ability, reproductive quality, age or reproductive status. Colour was not related to female rank or quality (body mass index, age at first birth or mean inter-birth interval); however, colour did increase significantly with age and primiparous females were darker than multiparous females. Colour may therefore signal reproductive quality, as younger females are less fertile and produce smaller offspring. Colour was brighter during the follicular phase than during the luteal phase, suggesting that it may signal fertility. Colour also varied across gestation and peaked at four and eight weeks post-parturition, suggesting that it may signal approaching parturition and lactation. Future studies should examine the relationship between colour and the menstrual cycle in more detail, the hormonal basis of female colour, and determine experimentally whether mandrills of both sexes attend to differences in colour between and within females.

Evolution of iris colour in relation to cavity nesting and parental care in passerine birds.

PubMed

Davidson, Gabrielle L; Thornton, Alex; Clayton, Nicola S

2017-01-01

Strong selection pressures are known to act on animal coloration. Although many animals vary in eye colour, virtually no research has investigated the functional significance of these colour traits. Passeriformes have a range of iris colours, making them an ideal system to investigate how and why iris colour has evolved. Using phylogenetic comparative methods, we tested the hypothesis that conspicuous iris colour in passerine birds evolved in response to (a) coordination of offspring care and (b) cavity nesting, two traits thought to be involved in intra-specific gaze sensitivity. We found that iris colour and cooperative offspring care by two or more individuals evolved independently, suggesting that bright eyes are not important for coordinating parental care through eye gaze. Furthermore, we found that evolution between iris colour and nesting behaviour did occur in a dependent manner, but contrary to predictions, transitions to coloured eyes were not more frequent in cavity nesters than non-cavity nesters. Instead, our results indicate that selection away from having bright eyes was much stronger in non-cavity nesters than cavity nesters, perhaps because conspicuous eye coloration in species not concealed within a cavity would be more visible to predators. © 2017 The Authors.

Perception of Safety and Liking Associated to the Colour Intervention of Bike Lanes: Contribution from the Behavioural Sciences to Urban Design and Wellbeing.

PubMed

Vera-Villarroel, Pablo; Contreras, Daniela; Lillo, Sebastián; Beyle, Christian; Segovia, Ariel; Rojo, Natalia; Moreno, Sandra; Oyarzo, Francisco

2016-01-01

The perception of colour and its subjective effects are key issues to designing safe and enjoyable bike lanes. This paper addresses the relationship between the colours of bike lane interventions-in particular pavement painting and intersection design-and the subjective evaluation of liking, visual saliency, and perceived safety related to such an intervention. Utilising images of three real bike lane intersections modified by software to change their colour (five in total), this study recruited 538 participants to assess their perception of all fifteen colour-design combinations. A multivariate analysis of covariance (MANCOVA) with the Bonferroni post hoc test was performed to assess the effect of the main conditions (colour and design) on the dependent variables (liking towards the intervention, level of visual saliency of the intersection, and perceived safety of the bike lane). The results showed that the colour red was more positively associated to the outcome variables, followed by yellow and blue. Additionally, it was observed that the effect of colour widely outweighs the effect of design, suggesting that the right choice and use of colour would increase the effectiveness on bike-lanes pavement interventions. Limitations and future directions are discussed.

Reversible colour change in Arthropoda.

PubMed

Umbers, Kate D L; Fabricant, Scott A; Gawryszewski, Felipe M; Seago, Ainsley E; Herberstein, Marie E

2014-11-01

The mechanisms and functions of reversible colour change in arthropods are highly diverse despite, or perhaps due to, the presence of an exoskeleton. Physiological colour changes, which have been recorded in 90 arthropod species, are rapid and are the result of changes in the positioning of microstructures or pigments, or in the refractive index of layers in the integument. By contrast, morphological colour changes, documented in 31 species, involve the anabolism or catabolism of components (e.g. pigments) directly related to the observable colour. In this review we highlight the diversity of mechanisms by which reversible colour change occurs and the evolutionary context and diversity of arthropod taxa in which it has been observed. Further, we discuss the functions of reversible colour change so far proposed, review the limited behavioural and ecological data, and argue that the field requires phylogenetically controlled approaches to understanding the evolution of reversible colour change. Finally, we encourage biologists to explore new model systems for colour change and to engage scientists from other disciplines; continued cross-disciplinary collaboration is the most promising approach to this nexus of biology, physics, and chemistry. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

Evolution of iris colour in relation to cavity nesting and parental care in passerine birds

PubMed Central

Thornton, Alex

2017-01-01

Strong selection pressures are known to act on animal coloration. Although many animals vary in eye colour, virtually no research has investigated the functional significance of these colour traits. Passeriformes have a range of iris colours, making them an ideal system to investigate how and why iris colour has evolved. Using phylogenetic comparative methods, we tested the hypothesis that conspicuous iris colour in passerine birds evolved in response to (a) coordination of offspring care and (b) cavity nesting, two traits thought to be involved in intra-specific gaze sensitivity. We found that iris colour and cooperative offspring care by two or more individuals evolved independently, suggesting that bright eyes are not important for coordinating parental care through eye gaze. Furthermore, we found that evolution between iris colour and nesting behaviour did occur in a dependent manner, but contrary to predictions, transitions to coloured eyes were not more frequent in cavity nesters than non-cavity nesters. Instead, our results indicate that selection away from having bright eyes was much stronger in non-cavity nesters than cavity nesters, perhaps because conspicuous eye coloration in species not concealed within a cavity would be more visible to predators. PMID:28077686

Conspicuous plumage colours are highly variable

PubMed Central

Szecsenyi, Beatrice; Nakagawa, Shinichi; Peters, Anne

2017-01-01

Elaborate ornamental traits are often under directional selection for greater elaboration, which in theory should deplete underlying genetic variation. Despite this, many ornamental traits appear to remain highly variable and how this essential variation is maintained is a key question in evolutionary biology. One way to address this question is to compare differences in intraspecific variability across different types of traits to determine whether high levels of variation are associated with specific trait characteristics. Here we assess intraspecific variation in more than 100 plumage colours across 55 bird species to test whether colour variability is linked to their level of elaboration (indicated by degree of sexual dichromatism and conspicuousness) or their condition dependence (indicated by mechanism of colour production). Conspicuous colours had the highest levels of variation and conspicuousness was the strongest predictor of variability, with high explanatory power. After accounting for this, there were no significant effects of sexual dichromatism or mechanisms of colour production. Conspicuous colours may entail higher production costs or may be more sensitive to disruptions during production. Alternatively, high variability could also be related to increased perceptual difficulties inherent to discriminating highly elaborate colours. Such psychophysical effects may constrain the exaggeration of animal colours. PMID:28100823

Conspicuous plumage colours are highly variable.

PubMed

Delhey, Kaspar; Szecsenyi, Beatrice; Nakagawa, Shinichi; Peters, Anne

2017-01-25

Elaborate ornamental traits are often under directional selection for greater elaboration, which in theory should deplete underlying genetic variation. Despite this, many ornamental traits appear to remain highly variable and how this essential variation is maintained is a key question in evolutionary biology. One way to address this question is to compare differences in intraspecific variability across different types of traits to determine whether high levels of variation are associated with specific trait characteristics. Here we assess intraspecific variation in more than 100 plumage colours across 55 bird species to test whether colour variability is linked to their level of elaboration (indicated by degree of sexual dichromatism and conspicuousness) or their condition dependence (indicated by mechanism of colour production). Conspicuous colours had the highest levels of variation and conspicuousness was the strongest predictor of variability, with high explanatory power. After accounting for this, there were no significant effects of sexual dichromatism or mechanisms of colour production. Conspicuous colours may entail higher production costs or may be more sensitive to disruptions during production. Alternatively, high variability could also be related to increased perceptual difficulties inherent to discriminating highly elaborate colours. Such psychophysical effects may constrain the exaggeration of animal colours. © 2017 The Author(s).

Finding counterparts for all-sky X-ray surveys with NWAY: a Bayesian algorithm for cross-matching multiple catalogues

NASA Astrophysics Data System (ADS)

Salvato, M.; Buchner, J.; Budavári, T.; Dwelly, T.; Merloni, A.; Brusa, M.; Rau, A.; Fotopoulou, S.; Nandra, K.

2018-02-01

We release the AllWISE counterparts and Gaia matches to 106 573 and 17 665 X-ray sources detected in the ROSAT 2RXS and XMMSL2 surveys with |b| > 15°. These are the brightest X-ray sources in the sky, but their position uncertainties and the sparse multi-wavelength coverage until now rendered the identification of their counterparts a demanding task with uncertain results. New all-sky multi-wavelength surveys of sufficient depth, like AllWISE and Gaia, and a new Bayesian statistics based algorithm, NWAY, allow us, for the first time, to provide reliable counterpart associations. NWAY extends previous distance and sky density based association methods and, using one or more priors (e.g. colours, magnitudes), weights the probability that sources from two or more catalogues are simultaneously associated on the basis of their observable characteristics. Here, counterparts have been determined using a Wide-field Infrared Survey Explorer (WISE) colour-magnitude prior. A reference sample of 4524 XMM/Chandra and Swift X-ray sources demonstrates a reliability of ∼94.7 per cent (2RXS) and 97.4 per cent (XMMSL2). Combining our results with Chandra-COSMOS data, we propose a new separation between stars and AGN in the X-ray/WISE flux-magnitude plane, valid over six orders of magnitude. We also release the NWAY code and its user manual. NWAY was extensively tested with XMM-COSMOS data. Using two different sets of priors, we find an agreement of 96 per cent and 99 per cent with published Likelihood Ratio methods. Our results were achieved faster and without any follow-up visual inspection. With the advent of deep and wide area surveys in X-rays (e.g. SRG/eROSITA, Athena/WFI) and radio (ASKAP/EMU, LOFAR, APERTIF, etc.) NWAY will provide a powerful and reliable counterpart identification tool.

Relationship between colorimetric (instrumental) evaluation and consumer-defined beef colour acceptability.

PubMed

Holman, Benjamin W B; Mao, Yanwei; Coombs, Cassius E O; van de Ven, Remy J; Hopkins, David L

2016-11-01

The relationship between instrumental colorimetric values (L*, a*, b*, the ratio of reflectance at 630nm and 580nm) and consumer perception of acceptable beef colour was evaluated using a web-based survey and standardised photographs of beef m. longissimus lumborum with known colorimetrics. Only L* and b* were found to relate to average consumer opinions of beef colour acceptability. Respondent nationality was also identified as a source of variation in beef colour acceptability score. Although this is a preliminary study with the findings necessitating additional investigation, these results suggest L* and b* as candidates for developing instrumental thresholds for consumer beef colour expectations. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Ineffective crypsis in a crab spider: a prey community perspective

PubMed Central

Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

2010-01-01

Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts upon. We carried out a manipulative field experiment using a complete factorial design resulting in six different colour combinations of crab spiders and flowers differing in their degree of colour-matching. A rich and diverse set of naturally occurring insects visited the flowers while we continuously video-recorded the spider's foraging activity. This enabled us to test the crypsis, the spider avoidance and the flower visitor attraction hypotheses, all three supported by previous studies. Flower visitors of different groups either avoided crab spiders independent of colour-matching, such as solitary bees and syrphid flies, or ignored them, such as bumble-bees and honeybees. Moreover, colour-matched spiders did not have a higher encounter rate and capture success compared to the visually apparent ones. Thus, our results support the spider avoidance hypothesis, reject the two other hypotheses and uncovered a fourth behaviour: indifference to predators. Because flower visitors reacted differently, a community approach is mandatory in order to understand the function of background colour-matching in generalist predators. We discuss our results in relation to the size and sociality of the prey and in relation to the functional significance of colour change in this predator. PMID:19889699

Ineffective crypsis in a crab spider: a prey community perspective.

PubMed

Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

2010-03-07

Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts upon. We carried out a manipulative field experiment using a complete factorial design resulting in six different colour combinations of crab spiders and flowers differing in their degree of colour-matching. A rich and diverse set of naturally occurring insects visited the flowers while we continuously video-recorded the spider's foraging activity. This enabled us to test the crypsis, the spider avoidance and the flower visitor attraction hypotheses, all three supported by previous studies. Flower visitors of different groups either avoided crab spiders independent of colour-matching, such as solitary bees and syrphid flies, or ignored them, such as bumble-bees and honeybees. Moreover, colour-matched spiders did not have a higher encounter rate and capture success compared to the visually apparent ones. Thus, our results support the spider avoidance hypothesis, reject the two other hypotheses and uncovered a fourth behaviour: indifference to predators. Because flower visitors reacted differently, a community approach is mandatory in order to understand the function of background colour-matching in generalist predators. We discuss our results in relation to the size and sociality of the prey and in relation to the functional significance of colour change in this predator.

Estimating the attributable fraction for melanoma: a meta-analysis of pigmentary characteristics and freckling.

PubMed

Olsen, Catherine M; Carroll, Heidi J; Whiteman, David C

2010-11-15

Epidemiologic research has demonstrated convincingly that certain pigmentary characteristics are associated with increased relative risks of melanoma; however there has been no comprehensive review to rank these characteristics in order of their importance on a population level. We conducted a systematic review of the literature and meta-analysis to quantify the contribution of pigmentary characteristics to melanoma, estimated by the population-attributable fraction (PAF). Eligible studies were those that permitted quantitative assessment of the association between histologically confirmed melanoma and hair colour, eye colour, skin phototype and presence of freckling; we identified 66 such studies using citation databases, followed by manual review of retrieved references. We calculated summary relative risks using weighted averages of the log RR, taking into account random effects, and used these to estimate the PAF. The pooled RRs for pigmentary characteristics were: 2.64 for red/red-blond, 2.0 for blond and 1.46 for light brown hair colour (vs. dark); 1.57 for blue/blue-grey and 1.51 for green/grey/hazel eye colour (vs. dark); 2.27, 1.99 and 1.35 for skin phototypes I, II and III respectively (vs. IV); and 1.99 for presence of freckling. The highest PAFs were observed for skin phototypes 1/II (0.27), presence of freckling (0.23), and blond hair colour (0.23). For eye colour, the PAF for blue/blue-grey eye colour was higher than for green/grey/hazel eye colour (0.18 vs. 0.13). The PAF of melanoma associated with red hair colour was 0.10. These estimates of melanoma burden attributable to pigmentary characteristics provide a basis for designing prevention strategies for melanoma.

An Entertaining Method of Teaching Concepts of Linear Light Propagation, Reflection and Refraction Using a Simple Optical Mechanism

ERIC Educational Resources Information Center

Yurumezoglu, K.

2009-01-01

An activity has been designed for the purpose of teaching how light is dispersed in a straight line and about the interaction between matter and light as well as the related concepts of shadows, partial shadows, reflection, refraction, primary colours and complementary (secondary) colours, and differentiating the relationship between colours, all…

The O-(Al2) centre in topaz and its relation to the blue colour

NASA Astrophysics Data System (ADS)

da Silva, D. N.; Guedes, K. J.; Pinheiro, M. V. B.; Schweizer, S.; Spaeth, J.-M.; Krambrock, K.

2005-01-01

Colour-enhanced blue topaz is one of the most traded gemstones. Naturally very rare, mostly topaz is irradiated by neutrons, electrons, gamma radiation and combinations of them. The colour centre is still not identified. It was speculated that it is related to a Si dangling bond defect occupied by two electrons with spin S = 0. We investigated natural blue as well as colourless topaz from different regions in Brazil by electron paramagnetic resonance (EPR), optical absorption and Raman spectroscopy. The results are compared with neutron and gamma-irradiated blue topaz. By EPR two paramagnetic defects are identified in all samples: (i) the peroxy radical (O2-) measured at room temperature and (ii) an (O-) hole centre interacting with two equivalent Al neighbours measured at low temperature. Blue samples show an absorption band centred at 620 nm which is responsible for the blue colour. From our investigation we find that the O-(Al2) hole centre has nearly the same thermal stability as the optical absorption band. However, we cannot say whether it is responsible for the absorption band and the blue colour. We suggest that at least it plays a dominant role in the stabilization of the blue colour.

VizieR Online Data Catalog: VEGAS-SSS photometry of NGC3115 (Cantiello+, 2015)

NASA Astrophysics Data System (ADS)

Cantiello, M.; Capaccioli, M.; Napolitano, N.; Grado, A.; Limatola, L.; Paolillo, M.; Iodice, E.; Romanowsky, A. J.; Forbes, D. A.; Raimondo, G.; Spavone, M.; La Barbera, F.; Puzia, T. H.; Schipani, P.

2015-03-01

We present g and i band photometry for ~47000 extended and point-like objects in the ~0.8 square degree area centred on NGC3115. For ~30000 object in the catalogue, structural parameters are also available. For each object equatorial coordinates, galactocentric distance from the photometric center of NGC3115, magnitudes in g and i bands (SDSS calibrated), colour, local extinction and sctructural parameters. (1 data file).

Artificial selection for food colour preferences.

PubMed

Cole, Gemma L; Endler, John A

2015-04-07

Colour is an important factor in food detection and acquisition by animals using visually based foraging. Colour can be used to identify the suitability of a food source or improve the efficiency of food detection, and can even be linked to mate choice. Food colour preferences are known to exist, but whether these preferences are heritable and how these preferences evolve is unknown. Using the freshwater fish Poecilia reticulata, we artificially selected for chase behaviour towards two different-coloured moving stimuli: red and blue spots. A response to selection was only seen for chase behaviours towards the red, with realized heritabilities ranging from 0.25 to 0.30. Despite intense selection, no significant chase response was recorded for the blue-selected lines. This lack of response may be due to the motion-detection mechanism in the guppy visual system and may have novel implications for the evolvability of responses to colour-related signals. The behavioural response to several colours after five generations of selection suggests that the colour opponency system of the fish may regulate the response to selection. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Effect of light, packaging condition and dark storage durations on colour and lipid oxidative stability of cooked ham.

PubMed

Haile, Demewez Moges; De Smet, Stefaan; Claeys, Erik; Vossen, Els

2013-04-01

The colour and lipid oxidative stability of sliced cooked ham stored at 4 °C were studied in relation to dark storage duration, lighting and packaging conditions. Colour stability was monitored by instrumental colour measurement (CIE L*a*b* colour space) whereas lipid stability was measured by the determination of the 2-thiobarbituric acid reactive substances (TBARS). A significantly higher discoloration observed in products wrapped in foil and kept in light than products wrapped in foil and kept in dark. Colour loss was estimated by loss of redness (a*), a*/b*, nitrosomyoglobin, chroma (C); or increase of lightness (L*), MetMb, hue angle (H°). Colour loss was more dependent upon photochemical process than dark storage duration and packaging types. Lipid oxidation was not significantly affected by light exposure. However lipid oxidation was significantly affected by dark storage duration as noticed from better lipid stability of products stored for short duration in dark. Better colour stability was observed on products packed in MAP with less residual oxygen.

Adaptive Colour Contrast Coding in the Salamander Retina Efficiently Matches Natural Scene Statistics

PubMed Central

Vasserman, Genadiy; Schneidman, Elad; Segev, Ronen

2013-01-01

The visual system continually adjusts its sensitivity to the statistical properties of the environment through an adaptation process that starts in the retina. Colour perception and processing is commonly thought to occur mainly in high visual areas, and indeed most evidence for chromatic colour contrast adaptation comes from cortical studies. We show that colour contrast adaptation starts in the retina where ganglion cells adjust their responses to the spectral properties of the environment. We demonstrate that the ganglion cells match their responses to red-blue stimulus combinations according to the relative contrast of each of the input channels by rotating their functional response properties in colour space. Using measurements of the chromatic statistics of natural environments, we show that the retina balances inputs from the two (red and blue) stimulated colour channels, as would be expected from theoretical optimal behaviour. Our results suggest that colour is encoded in the retina based on the efficient processing of spectral information that matches spectral combinations in natural scenes on the colour processing level. PMID:24205373

Artificial selection for food colour preferences

PubMed Central

Cole, Gemma L.; Endler, John A.

2015-01-01

Colour is an important factor in food detection and acquisition by animals using visually based foraging. Colour can be used to identify the suitability of a food source or improve the efficiency of food detection, and can even be linked to mate choice. Food colour preferences are known to exist, but whether these preferences are heritable and how these preferences evolve is unknown. Using the freshwater fish Poecilia reticulata, we artificially selected for chase behaviour towards two different-coloured moving stimuli: red and blue spots. A response to selection was only seen for chase behaviours towards the red, with realized heritabilities ranging from 0.25 to 0.30. Despite intense selection, no significant chase response was recorded for the blue-selected lines. This lack of response may be due to the motion-detection mechanism in the guppy visual system and may have novel implications for the evolvability of responses to colour-related signals. The behavioural response to several colours after five generations of selection suggests that the colour opponency system of the fish may regulate the response to selection. PMID:25740894

Iridescent colour production in hairs of blind golden moles (Chrysochloridae).

PubMed

Snyder, Holly K; Maia, Rafael; D'Alba, Liliana; Shultz, Allison J; Rowe, Karen M C; Rowe, Kevin C; Shawkey, Matthew D

2012-06-23

Relative to other metazoans, the mammalian integument is thought to be limited in colour. In particular, while iridescence is widespread among birds and arthropods, it has only rarely been reported in mammals. Here, we examine the colour, morphology and optical mechanisms in hairs from four species of golden mole (Mammalia: Chrysochloridae) that are characterized by sheens ranging from purple to green. Microspectrophotometry reveals that this colour is weak and variable. Iridescent hairs are flattened and have highly reduced cuticular scales, providing a broad and smooth surface for light reflection. These scales form multiple layers of light and dark materials of consistent thickness, strikingly similar to those in the elytra of iridescent beetles. Optical modelling suggests that the multi-layers produce colour through thin-film interference, and that the sensitivity of this mechanism to slight changes in layer thickness and number explains colour variability. While coloured integumentary structures are typically thought to evolve as sexual ornaments, the blindness of golden moles suggests that the colour may be an epiphenomenon resulting from evolution via other selective factors, including the ability to move and keep clean in dirt and sand.

Reduced Chromatic Discrimination in Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Franklin, Anna; Sowden, Paul; Notman, Leslie; Gonzalez-Dixon, Melissa; West, Dorotea; Alexander, Iona; Loveday, Stephen; White, Alex

2010-01-01

Atypical perception in Autism Spectrum Disorders (ASD) is well documented (Dakin & Frith, 2005). However, relatively little is known about colour perception in ASD. Less accurate performance on certain colour tasks has led some to argue that chromatic discrimination is reduced in ASD relative to typical development (Franklin, Sowden, Burley,…

Protection against ultraviolet radiation by commercial summer clothing: need for standardised testing and labelling

PubMed Central

Gambichler, Thilo; Rotterdam, Sebastian; Altmeyer, Peter; Hoffmann, Klaus

2001-01-01

Background The use of clothing as a means of sun protection has been recommended in recent education campaigns. Contrary to popular opinion, however, some fabrics provide insufficient ultraviolet (UV) protection. Material and methods We investigated 236 apparel textiles of the spring/summer collections 2000 and 2001. In accordance with the forthcoming European standard the UV protection factor (UPF) of the fabrics was determined spectrophotometrically. Results Seventy-eight (33%) fabrics had UPF < 15, 45 (19%) had UPF = or > 15 and < 30, and 113 (48%) had UPF = or > 30 (30+). More than 70% of the wool, polyester, and fabric blends, and only less than 30% of the cotton, linen, and viscose fabrics had UPF values of 30+. Fabrics with black, navy-blue, white, green, or beige colours provided most frequently UPF values of 30+. Conclusions It is difficult for the sun-aware consumer to choose the 'right' garment, with a third of summer clothing providing insufficient UV protection and only half of the fabrics having UPF 30+, the UPF recommended by the European standard. Therefore, apparel summer fabrics should be measured and labelled in accordance with a standard document. PMID:11710968

Colour Preference to Emotions in Relation to the Anxiety Level among School Children in Puducherry – A Cross-Sectional Study

PubMed Central

Prathima, Gajula Shivashankarappa; Sajeev, Renganathan; Kayalvizhi, Gurusamy; Ramesh, Venkatesan; Ezhumalai, Govindasamy

2016-01-01

Introduction Dental setting plays an important role in child’s behavior and cooperation to the planned dental treatment. Adding attractive colours to the dental environment and by incorporating colourful equipments can make the child feel good and be at ease. This study tries to convey the relationship between colours and dental anxiety among children. Aim To evaluate the colour preference to emotions in relation to children’s age, gender and anxiety level. Materials and Methods A total of 382 children aged 6-12 years were randomly selected from schools in and around Puducherry. Modified dental anxiety scale was recorded by a calibrated examiner. Each question was scored from one (not anxious) to five (extremely anxious); such that the total score ranges from 5 to 25, wherein a score of 15 or more was considered to be anxious. Based on this, children were divided into anxious and non-anxious groups. All the children were provided with eight different coloured crayon pencils and were asked to shade two cartoon emoticons indicating happiness and sadness with their preferred colour. Values were tabulated and statistically analyzed to evaluate the association between the variables using Z test, Chi-square, Chi-square goodness of fit and odds ratio. (p≤0.05 was considered statistically significant). Results Among 382 children, 77% (294) were graded as anxious and 23% (88) as non- anxious. For positive emotion (happiness), 31.2% (119) children preferred blue followed by pink 29.3% (112). For negative emotion (sadness), 52.1% (199) of children preferred black and 46.9% (179) preferred red. Association between colour and emotion was highly significant (p= 0.005). Conclusion From the colours preferred by the children in our study, it can be concluded that colours like blue and pink in the dental set-up could enhance a positive attitude while black and red could develop a negative outlook in their mind. PMID:27630948

Colour Preference to Emotions in Relation to the Anxiety Level among School Children in Puducherry - A Cross-Sectional Study.

PubMed

Annamary, Kattakayam; Prathima, Gajula Shivashankarappa; Sajeev, Renganathan; Kayalvizhi, Gurusamy; Ramesh, Venkatesan; Ezhumalai, Govindasamy

2016-07-01

Dental setting plays an important role in child's behavior and cooperation to the planned dental treatment. Adding attractive colours to the dental environment and by incorporating colourful equipments can make the child feel good and be at ease. This study tries to convey the relationship between colours and dental anxiety among children. To evaluate the colour preference to emotions in relation to children's age, gender and anxiety level. A total of 382 children aged 6-12 years were randomly selected from schools in and around Puducherry. Modified dental anxiety scale was recorded by a calibrated examiner. Each question was scored from one (not anxious) to five (extremely anxious); such that the total score ranges from 5 to 25, wherein a score of 15 or more was considered to be anxious. Based on this, children were divided into anxious and non-anxious groups. All the children were provided with eight different coloured crayon pencils and were asked to shade two cartoon emoticons indicating happiness and sadness with their preferred colour. Values were tabulated and statistically analyzed to evaluate the association between the variables using Z test, Chi-square, Chi-square goodness of fit and odds ratio. (p≤0.05 was considered statistically significant). Among 382 children, 77% (294) were graded as anxious and 23% (88) as non- anxious. For positive emotion (happiness), 31.2% (119) children preferred blue followed by pink 29.3% (112). For negative emotion (sadness), 52.1% (199) of children preferred black and 46.9% (179) preferred red. Association between colour and emotion was highly significant (p= 0.005). From the colours preferred by the children in our study, it can be concluded that colours like blue and pink in the dental set-up could enhance a positive attitude while black and red could develop a negative outlook in their mind.

Understanding the contribution of phytoplankton phase functions to uncertainties in the water colour signal.

PubMed

Lain, Lisl Robertson; Bernard, Stewart; Matthews, Mark W

2017-02-20

The accurate description of a water body's volume scattering function (VSF), and hence its phase functions, is critical to the determination of the constituent inherent optical properties (IOPs), the associated spectral water-leaving reflectance, and consequently the retrieval of phytoplankton functional type (PFT) information. The equivalent algal populations (EAP) model has previously been evaluated for phytoplankton-dominated waters, and offers the ability to provide phytoplankton population-specific phase functions, unveiling a new opportunity to further understanding of the causality of the PFT signal. This study presents and evaluates the wavelength dependent, spectrally variable EAP particle phase functions and the subsequent effects on water-leaving reflectance. Comparisons are made with frequently used phase function approximations e.g. the Fournier Forand formulation, as well as with phase functions inferred from measured VSFs in coastal waters. Relative differences in shape and magnitude are quantified. Reflectance modelled with the EAP phase functions is then compared against measured reflectance data from phytoplankton-dominated waters. Further examples of modelled phytoplankton-dominated waters are discussed with reference to choice of phase function for two PFTs (eukaryote and prokaryote) across a range of biomass. Finally a demonstration of the sensitivity of reflectance due to the choice of phase function is presented. The EAP model phase functions account for both spectral and angular variability in phytoplankton backscattering i.e. they display variability which is both spectral and shape-related. It is concluded that phase functions modelled in this way are necessary for investigating the effects of assemblage variability on the ocean colour signal, and should be considered for model closure even in relatively low scattering conditions where phytoplankton dominate the IOPs.

GAMA/H-ATLAS: the ultraviolet spectral slope and obscuration in galaxies

NASA Astrophysics Data System (ADS)

Wijesinghe, D. B.; da Cunha, E.; Hopkins, A. M.; Dunne, L.; Sharp, R.; Gunawardhana, M.; Brough, S.; Sadler, E. M.; Driver, S.; Baldry, I.; Bamford, S.; Liske, J.; Loveday, J.; Norberg, P.; Peacock, J.; Popescu, C. C.; Tuffs, R.; Andrae, E.; Auld, R.; Baes, M.; Bland-Hawthorn, J.; Buttiglione, S.; Cava, A.; Cameron, E.; Conselice, C. J.; Cooray, A.; Croom, S.; Dariush, A.; Dezotti, G.; Dye, S.; Eales, S.; Frenk, C.; Fritz, J.; Hill, D.; Hopwood, R.; Ibar, E.; Ivison, R.; Jarvis, M.; Jones, D. H.; van Kampen, E.; Kelvin, L.; Kuijken, K.; Maddox, S. J.; Madore, B.; Michałowski, M. J.; Nichol, B.; Parkinson, H.; Pascale, E.; Pimbblet, K. A.; Pohlen, M.; Prescott, M.; Rhodighiero, G.; Robotham, A. S. G.; Rigby, E. E.; Seibert, M.; Sergeant, S.; Smith, D. J. B.; Temi, P.; Sutherland, W.; Taylor, E.; Thomas, D.; van der Werf, P.

2011-08-01

We use multiwavelength data from the Galaxy And Mass Assembly (GAMA) and Herschel-ATLAS (H-ATLAS) surveys to compare the relationship between various dust obscuration measures in galaxies. We explore the connections between the ultraviolet (UV) spectral slope, β, the Balmer decrement and the far-infrared (FIR) to 150 nm far-ultraviolet (FUV) luminosity ratio. We explore trends with galaxy mass, star formation rate (SFR) and redshift in order to identify possible systematics in these various measures. We reiterate the finding of other authors that there is a large scatter between the Balmer decrement and the β parameter, and that β may be poorly constrained when derived from only two broad passbands in the UV. We also emphasize that FUV-derived SFRs, corrected for dust obscuration using β, will be overestimated unless a modified relation between β and the attenuation factor is used. Even in the optimum case, the resulting SFRs have a significant scatter, well over an order of magnitude. While there is a stronger correlation between the IR-to-FUV luminosity ratio and β parameter than with the Balmer decrement, neither of these correlations are particularly tight, and dust corrections based on β for high-redshift galaxy SFRs must be treated with caution. We conclude with a description of the extent to which the different obscuration measures are consistent with each other as well as the effects of including other galactic properties on these correlations.

Motorcycle rider conspicuity and crash related injury: case-control study.

PubMed

Wells, Susan; Mullin, Bernadette; Norton, Robyn; Langley, John; Connor, Jennie; Lay-Yee, Roy; Jackson, Rod

2004-04-10

To investigate whether the risk of motorcycle crash related injuries is associated with the conspicuity of the driver or vehicle. Population based case-control study. Auckland region of New Zealand from February 1993 to February 1996. 463 motorcycle drivers (cases) involved in crashes leading to hospital treatment or death; 1233 motorcycle drivers (controls) recruited from randomly selected roadside survey sites. Estimates of relative risk of motorcycle crash related injury and population attributable risk associated with conspicuity measures, including the use of reflective or fluorescent clothing, headlight operation, and colour of helmet, clothing, and motorcycle. Crash related injuries occurred mainly in urban zones with 50 km/h speed limit (66%), during the day (63%), and in fine weather (72%). After adjustment for potential confounders, drivers wearing any reflective or fluorescent clothing had a 37% lower risk (multivariate odds ratio 0.63, 95% confidence interval 0.42 to 0.94) than other drivers. Compared with wearing a black helmet, use of a white helmet was associated with a 24% lower risk (multivariate odds ratio 0.76, 0.57 to 0.99). Self reported light coloured helmet versus dark coloured helmet was associated with a 19% lower risk. Three quarters of motorcycle riders had their headlight turned on during the day, and this was associated with a 27% lower risk (multivariate odds ratio 0.73, 0.53 to 1.00). No association occurred between risk and the frontal colour of drivers' clothing or motorcycle. If these odds ratios are unconfounded, the population attributable risks are 33% for wearing no reflective or fluorescent clothing, 18% for a non-white helmet, 11% for a dark coloured helmet, and 7% for no daytime headlight operation. Low conspicuity may increase the risk of motorcycle crash related injury. Increasing the use of reflective or fluorescent clothing, white or light coloured helmets, and daytime headlights are simple, cheap interventions that could considerably reduce motorcycle crash related injury and death.

Motorcycle rider conspicuity and crash related injury: case-control study

PubMed Central

Wells, Susan; Mullin, Bernadette; Norton, Robyn; Langley, John; Connor, Jennie; Lay-Yee, Roy; Jackson, Rod

2004-01-01

Objective To investigate whether the risk of motorcycle crash related injuries is associated with the conspicuity of the driver or vehicle. Design Population based case-control study. Setting Auckland region of New Zealand from February 1993 to February 1996. Participants 463 motorcycle drivers (cases) involved in crashes leading to hospital treatment or death; 1233 motorcycle drivers (controls) recruited from randomly selected roadside survey sites. Main outcome measures Estimates of relative risk of motorcycle crash related injury and population attributable risk associated with conspicuity measures, including the use of reflective or fluorescent clothing, headlight operation, and colour of helmet, clothing, and motorcycle. Results Crash related injuries occurred mainly in urban zones with 50 km/h speed limit (66%), during the day (63%), and in fine weather (72%). After adjustment for potential confounders, drivers wearing any reflective or fluorescent clothing had a 37% lower risk (multivariate odds ratio 0.63, 95% confidence interval 0.42 to 0.94) than other drivers. Compared with wearing a black helmet, use of a white helmet was associated with a 24% lower risk (multivariate odds ratio 0.76, 0.57 to 0.99). Self reported light coloured helmet versus dark coloured helmet was associated with a 19% lower risk. Three quarters of motorcycle riders had their headlight turned on during the day, and this was associated with a 27% lower risk (multivariate odds ratio 0.73, 0.53 to 1.00). No association occurred between risk and the frontal colour of drivers' clothing or motorcycle. If these odds ratios are unconfounded, the population attributable risks are 33% for wearing no reflective or fluorescent clothing, 18% for a non-white helmet, 11% for a dark coloured helmet, and 7% for no daytime headlight operation. Conclusions Low conspicuity may increase the risk of motorcycle crash related injury. Increasing the use of reflective or fluorescent clothing, white or light coloured helmets, and daytime headlights are simple, cheap interventions that could considerably reduce motorcycle crash related injury and death. PMID:14742349

A catalogue of chromospherically active binary stars (third edition)

NASA Astrophysics Data System (ADS)

Eker, Z.; Ak, N. Filiz; Bilir, S.; Doǧru, D.; Tüysüz, M.; Soydugan, E.; Bakış, H.; Uǧraş, B.; Soydugan, F.; Erdem, A.; Demircan, O.

2008-10-01

The catalogue of chromospherically active binaries (CABs) has been revised and updated. With 203 new identifications, the number of CAB stars is increased to 409. The catalogue is available in electronic format where each system has a number of lines (suborders) with a unique order number. The columns contain data of limited numbers of selected cross references, comments to explain peculiarities and the position of the binarity in case it belongs to a multiple system, classical identifications (RS Canum Venaticorum, BY Draconis), brightness and colours, photometric and spectroscopic data, a description of emission features (CaII H and K, Hα, ultraviolet, infrared), X-ray luminosity, radio flux, physical quantities and orbital information, where each basic entry is referenced so users can go to the original sources.

A comparison between ultraviolet disinfection and copper alginate beads within a vortex bioreactor for the deactivation of bacteria in simulated waste streams with high levels of colour, humic acid and suspended solids.

PubMed

Thomas, Simon F; Rooks, Paul; Rudin, Fabian; Atkinson, Sov; Goddard, Paul; Bransgrove, Rachel M; Mason, Paul T; Allen, Michael J

2014-01-01

We show in this study that the combination of a swirl flow reactor and an antimicrobial agent (in this case copper alginate beads) is a promising technique for the remediation of contaminated water in waste streams recalcitrant to UV-C treatment. This is demonstrated by comparing the viability of both common and UV-C resistant organisms in operating conditions where UV-C proves ineffective - notably high levels of solids and compounds which deflect UV-C. The swirl flow reactor is easy to construct from commonly available plumbing parts and may prove a versatile and powerful tool in waste water treatment in developing countries.

Variability in avian eggshell colour: a comparative study of museum eggshells.

PubMed

Cassey, Phillip; Portugal, Steven J; Maurer, Golo; Ewen, John G; Boulton, Rebecca L; Hauber, Mark E; Blackburn, Tim M

2010-08-09

The exceptional diversity of coloration found in avian eggshells has long fascinated biologists and inspired a broad range of adaptive hypotheses to explain its evolution. Three main impediments to understanding the variability of eggshell appearance are: (1) the reliable quantification of the variation in eggshell colours; (2) its perception by birds themselves, and (3) its relation to avian phylogeny. Here we use an extensive museum collection to address these problems directly, and to test how diversity in eggshell coloration is distributed among different phylogenetic levels of the class Aves. Spectrophotometric data on eggshell coloration were collected from a taxonomically representative sample of 251 bird species to determine the change in reflectance across different wavelengths and the taxonomic level where the variation resides. As many hypotheses for the evolution of eggshell coloration assume that egg colours provide a communication signal for an avian receiver, we also modelled reflectance spectra of shell coloration for the avian visual system. We found that a majority of species have eggs with similar background colour (long wavelengths) but that striking differences are just as likely to occur between congeners as between members of different families. The region of greatest variability in eggshell colour among closely related species coincided with the medium-wavelength sensitive region around 500 nm. The majority of bird species share similar background eggshell colours, while the greatest variability among species aligns with differences along a red-brown to blue axis that most likely corresponds with variation in the presence and concentration of two tetrapyrrole pigments responsible for eggshell coloration. Additionally, our results confirm previous findings of temporal changes in museum collections, and this will be of particular concern for studies testing intraspecific hypotheses relating temporal patterns to adaptation of eggshell colour. We suggest that future studies investigating the phylogenetic association between the composition and concentration of eggshell pigments, and between the evolutionary drivers and functional impacts of eggshell colour variability will be most rewarding.

Washington photometry of 14 intermediate-age to old star clusters in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Piatti, Andrés E.; Clariá, Juan J.; Bica, Eduardo; Geisler, Doug; Ahumada, Andrea V.; Girardi, Léo

2011-10-01

We present CCD photometry in the Washington system C, T1 and T2 passbands down to T1˜ 23 in the fields of L3, L28, HW 66, L100, HW 79, IC 1708, L106, L108, L109, NGC 643, L112, HW 84, HW 85 and HW 86, 14 Small Magellanic Cloud (SMC) clusters, most of them poorly studied objects. We measured T1 magnitudes and C-T1 and T1-T2 colours for a total of 213 516 stars spread throughout cluster areas of 14.7 × 14.7 arcmin2 each. We carried out an in-depth analysis of the field star contamination of the colour-magnitude diagrams (CMDs) and statistically cleaned the cluster CMDs. Based on the best fits of isochrones computed by the Padova group to the (T1, C-T1) CMDs, as well as from the δ(T1) index and the standard giant branch procedure, we derived ages and metallicities for the cluster sample. With the exception of IC 1708, a relatively metal-poor Hyades-age cluster, the remaining 13 objects are between intermediate and old age (from 1.0 to 6.3 Gyr), their [Fe/H] values ranging from -1.4 to -0.7 dex. By combining these results with others available in the literature, we compiled a sample of 43 well-known SMC clusters older than 1 Gyr, with which we produced a revised age distribution. We found that the present clusters' age distribution reveals two primary excesses of clusters at t˜ 2 and 5 Gyr, which engraves the SMC with clear signs of enhanced formation episodes at both ages. In addition, we found that from the birth of the SMC cluster system until approximately the first 4 Gyr of its lifetime, the cluster formation resembles that of a constant formation rate scenario.

Colour Perception in Ancient World

NASA Astrophysics Data System (ADS)

Nesterov, D. I.; Fedorova, M. Yu

2017-11-01

How did the human thought form the surrounding color information into the persistent semantic images of a mythological, pseudoscientific and religious nature? The concepts associated with colour perception are suggested. The existence of colour environment does not depend on the human consciousness. The colour culture formation is directly related to the level of the human consciousness development and the possibility to influence the worldview and culture. The colour perception of a person goes through the stages similar to the development of colour vision in a child. Like any development, the colour consciousness has undergone stages of growth and decline, evolution and stagnation. The way of life and difficult conditions for existence made their own adjustments to the development of the human perception of the surrounding world. Wars have been both a powerful engine of progress in all spheres of life and a great destructive force demolishing the already created and preserved heritage. The surrounding world has always been interesting for humans, evoked images and fantasies in the consciousness of ancient people. Unusual and inexplicable natural phenomena spawned numerous legends and myths which was reflected in the ancient art and architecture and, accordingly, in a certain manifestation of colour in the human society. The colour perception of the ancient man, his pragmatic, utilitarian attitude to colour is considered as well as the influence of dependence on external conditions of existence and their reflection in the colour culture of antiquity. “Natural Science” conducts research in the field of the colour nature and their authorial interpretation of the Hellenic period. Several authorial concepts of the ancient world have been considered.

ZnO nanowire Schottky barrier ultraviolet photodetector with high sensitivity and fast recovery speed

NASA Astrophysics Data System (ADS)

Cheng, Gang; Wu, Xinghui; Liu, Bing; Li, Bing; Zhang, Xingtang; Du, Zuliang

2011-11-01

ZnO nanowire (NW) ultraviolet (UV) photodetectors have high sensitivity, while the long recovery time is an important limitation for its applications. In this paper, we demonstrate the promising applications of ZnO NW Schottky barrier as high performance UV photodetector with high sensitivity and fast recovery speed. The on/off ratio, sensitivity, and photocurrent gain are 4 × 105, 2.6 × 103 A/W, and 8.5 × 103, respectively. The recovery time is 0.28 s when photocurrent decreases by 3 orders of magnitude, and the corresponding time constant is as short as 46 ms. The physical mechanisms of the fast recovery properties have also been discussed.

Ultraviolet laser ablation as technique for defect repair of GaN-based light-emitting diodes

NASA Astrophysics Data System (ADS)

Passow, Thorsten; Kunzer, Michael; Pfeuffer, Alexander; Binder, Michael; Wagner, Joachim

2018-03-01

Defect repair of GaN-based light-emitting diodes (LEDs) by ultraviolet laser micromachining is reported. Percussion and helical drilling in GaN by laser ablation were investigated using 248 nm nanosecond and 355 nm picosecond pulses. The influence of laser ablation including different laser parameters on electrical and optical properties of GaN-based LED chips was evaluated. The results for LEDs on sapphire with transparent conductive oxide p-type contact on top as well as for thin-film LEDs are reported. A reduction of leakage current by up to six orders in magnitude and homogeneous luminance distribution after proper laser defect treatment were achieved.

VUV dissociative excitation cross sections of H2O, NH3, and CH4 by electron impact. [Vacuum Ultra-Violet

NASA Technical Reports Server (NTRS)

Morgan, H. D.; Mentall, J. E.

1974-01-01

Absolute excitation functions for excited fragments resulting from electron bombardment of H2O, NH3, and CH4 by low-energy electrons (0 to 300 eV) have been measured in the vacuum ultraviolet (1100 to 1950 A). The predominant emission for each molecule was the H Lyman-alpha line, while the O I, N I, C I, and C II emissions were at least an order of magnitude weaker. Absolute cross sections at 100 eV are given along with the appearance potential of the various processes and the possible dissociative-excitation channels through which such processes proceed.

High Throughput, High Yield Fabrication of High Quantum Efficiency Back-Illuminated Photon Counting, Far UV, UV, and Visible Detector Arrays

NASA Technical Reports Server (NTRS)

Nikzad, Shouleh; Hoenk, M. E.; Carver, A. G.; Jones, T. J.; Greer, F.; Hamden, E.; Goodsall, T.

2013-01-01

In this paper we discuss the high throughput end-to-end post fabrication processing of high performance delta-doped and superlattice-doped silicon imagers for UV, visible, and NIR applications. As an example, we present our results on far ultraviolet and ultraviolet quantum efficiency (QE) in a photon counting, detector array. We have improved the QE by nearly an order of magnitude over microchannel plates (MCPs) that are the state-of-the-art UV detectors for many NASA space missions as well as defense applications. These achievements are made possible by precision interface band engineering of Molecular Beam Epitaxy (MBE) and Atomic Layer Deposition (ALD).

EUNIS; Extreme-Ultraviolet Normal-Incidence Spectrometer

NASA Technical Reports Server (NTRS)

Thomas, Roger J.; Davila, Joseph M.; Fisher, Richard R. (Technical Monitor)

2001-01-01

GSFC is in the process of assembling an Extreme-Ultraviolet Normal Incidence Spectrometer called EUNIS, to be flown as a sounding rocket payload. The instrument builds on the many technical innovations pioneered by our highly successful SERTS experiment, which has now flown a total of ten times, most recently last summer. The new design will have somewhat improved spatial and spectral resolutions, as well as two orders of magnitude greater sensitivity, permitting high signal/noise EUV spectroscopy with a temporal resolution near 1 second for the first time ever. In order to achieve such high time cadence, a novel detector system is being developed, based on Active-Pixel-Sensor electronics, a key component of our design.

Condition-dependence, pleiotropy and the handicap principle of sexual selection in melanin-based colouration.

PubMed

Roulin, Alexandre

2016-05-01

The signalling function of melanin-based colouration is debated. Sexual selection theory states that ornaments should be costly to produce, maintain, wear or display to signal quality honestly to potential mates or competitors. An increasing number of studies supports the hypothesis that the degree of melanism covaries with aspects of body condition (e.g. body mass or immunity), which has contributed to change the initial perception that melanin-based colour ornaments entail no costs. Indeed, the expression of many (but not all) melanin-based colour traits is weakly sensitive to the environment but strongly heritable suggesting that these colour traits are relatively cheap to produce and maintain, thus raising the question of how such colour traits could signal quality honestly. Here I review the production, maintenance and wearing/displaying costs that can generate a correlation between melanin-based colouration and body condition, and consider other evolutionary mechanisms that can also lead to covariation between colour and body condition. Because genes controlling melanic traits can affect numerous phenotypic traits, pleiotropy could also explain a linkage between body condition and colouration. Pleiotropy may result in differently coloured individuals signalling different aspects of quality that are maintained by frequency-dependent selection or local adaptation. Colouration may therefore not signal absolute quality to potential mates or competitors (e.g. dark males may not achieve a higher fitness than pale males); otherwise genetic variation would be rapidly depleted by directional selection. As a consequence, selection on heritable melanin-based colouration may not always be directional, but mate choice may be conditional to environmental conditions (i.e. context-dependent sexual selection). Despite the interest of evolutionary biologists in the adaptive value of melanin-based colouration, its actual role in sexual selection is still poorly understood. © 2015 Cambridge Philosophical Society.

Statistical colour models: an automated digital image analysis method for quantification of histological biomarkers.

PubMed

Shu, Jie; Dolman, G E; Duan, Jiang; Qiu, Guoping; Ilyas, Mohammad

2016-04-27

Colour is the most important feature used in quantitative immunohistochemistry (IHC) image analysis; IHC is used to provide information relating to aetiology and to confirm malignancy. Statistical modelling is a technique widely used for colour detection in computer vision. We have developed a statistical model of colour detection applicable to detection of stain colour in digital IHC images. Model was first trained by massive colour pixels collected semi-automatically. To speed up the training and detection processes, we removed luminance channel, Y channel of YCbCr colour space and chose 128 histogram bins which is the optimal number. A maximum likelihood classifier is used to classify pixels in digital slides into positively or negatively stained pixels automatically. The model-based tool was developed within ImageJ to quantify targets identified using IHC and histochemistry. The purpose of evaluation was to compare the computer model with human evaluation. Several large datasets were prepared and obtained from human oesophageal cancer, colon cancer and liver cirrhosis with different colour stains. Experimental results have demonstrated the model-based tool achieves more accurate results than colour deconvolution and CMYK model in the detection of brown colour, and is comparable to colour deconvolution in the detection of pink colour. We have also demostrated the proposed model has little inter-dataset variations. A robust and effective statistical model is introduced in this paper. The model-based interactive tool in ImageJ, which can create a visual representation of the statistical model and detect a specified colour automatically, is easy to use and available freely at http://rsb.info.nih.gov/ij/plugins/ihc-toolbox/index.html . Testing to the tool by different users showed only minor inter-observer variations in results.

Galaxy clusters in the SDSS Stripe 82 based on photometric redshifts

DOE PAGES

Durret, F.; Adami, C.; Bertin, E.; ...

2015-06-10

Based on a recent photometric redshift galaxy catalogue, we have searched for galaxy clusters in the Stripe ~82 region of the Sloan Digital Sky Survey by applying the Adami & MAzure Cluster FInder (AMACFI). Extensive tests were made to fine-tune the AMACFI parameters and make the cluster detection as reliable as possible. The same method was applied to the Millennium simulation to estimate our detection efficiency and the approximate masses of the detected clusters. Considering all the cluster galaxies (i.e. within a 1 Mpc radius of the cluster to which they belong and with a photoz differing by less thanmore » 0.05 from that of the cluster), we stacked clusters in various redshift bins to derive colour-magnitude diagrams and galaxy luminosity functions (GLFs). For each galaxy with absolute magnitude brighter than -19.0 in the r band, we computed the disk and spheroid components by applying SExtractor, and by stacking clusters we determined how the disk-to-spheroid flux ratio varies with cluster redshift and mass. We also detected 3663 clusters in the redshift range 0.1513 and a few 10 14 solar masses. Furthermore, by stacking the cluster galaxies in various redshift bins, we find a clear red sequence in the (g'-r') versus r' colour-magnitude diagrams, and the GLFs are typical of clusters, though with a possible contamination from field galaxies. The morphological analysis of the cluster galaxies shows that the fraction of late-type to early-type galaxies shows an increase with redshift (particularly in high mass clusters) and a decrease with detection level, i.e. cluster mass. From the properties of the cluster galaxies, the majority of the candidate clusters detected here seem to be real clusters with typical cluster properties.« less

Galaxy clusters in the SDSS Stripe 82 based on photometric redshifts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durret, F.; Adami, C.; Bertin, E.

Based on a recent photometric redshift galaxy catalogue, we have searched for galaxy clusters in the Stripe ~82 region of the Sloan Digital Sky Survey by applying the Adami & MAzure Cluster FInder (AMACFI). Extensive tests were made to fine-tune the AMACFI parameters and make the cluster detection as reliable as possible. The same method was applied to the Millennium simulation to estimate our detection efficiency and the approximate masses of the detected clusters. Considering all the cluster galaxies (i.e. within a 1 Mpc radius of the cluster to which they belong and with a photoz differing by less thanmore » 0.05 from that of the cluster), we stacked clusters in various redshift bins to derive colour-magnitude diagrams and galaxy luminosity functions (GLFs). For each galaxy with absolute magnitude brighter than -19.0 in the r band, we computed the disk and spheroid components by applying SExtractor, and by stacking clusters we determined how the disk-to-spheroid flux ratio varies with cluster redshift and mass. We also detected 3663 clusters in the redshift range 0.1513 and a few 10 14 solar masses. Furthermore, by stacking the cluster galaxies in various redshift bins, we find a clear red sequence in the (g'-r') versus r' colour-magnitude diagrams, and the GLFs are typical of clusters, though with a possible contamination from field galaxies. The morphological analysis of the cluster galaxies shows that the fraction of late-type to early-type galaxies shows an increase with redshift (particularly in high mass clusters) and a decrease with detection level, i.e. cluster mass. From the properties of the cluster galaxies, the majority of the candidate clusters detected here seem to be real clusters with typical cluster properties.« less

The role of luminance and chromatic cues in emmetropisation.

PubMed

Rucker, Frances J

2013-05-01

At birth most, but not all eyes, are hyperopic. Over the course of the first few years of life the refraction gradually becomes close to zero through a process called emmetropisation. This process is not thought to require accommodation, though a lag of accommodation has been implicated in myopia development, suggesting that the accuracy of accommodation is an important factor. This review will cover research on accommodation and emmetropisation that relates to the ability of the eye to use colour and luminance cues to guide the responses. There are three ways in which changes in luminance and colour contrast could provide cues: (1) The eye could maximize luminance contrast. Monochromatic light experiments have shown that the human eye can accommodate and animal eyes can emmetropise using changes in luminance contrast alone. However, by reducing the effectiveness of luminance cues in monochromatic and white light by introducing astigmatism, or by reducing light intensity, investigators have revealed that the eye also uses colour cues in emmetropisation. (2) The eye could compare relative cone contrast to derive the sign of defocus information from colour cues. Experiments involving simulations of the retinal image with defocus have shown that relative cone contrast can provide colour cues for defocus in accommodation and emmetropisation. In the myopic simulation the contrast of the red component of a sinusoidal grating was higher than that of the green and blue component and this caused relaxation of accommodation and reduced eye growth. In the hyperopic simulation the contrast of the blue component was higher than that of the green and red components and this caused increased accommodation and increased eye growth. (3) The eye could compare the change in luminance and colour contrast as the eye changes focus. An experiment has shown that changes in colour or luminance contrast can provide cues for defocus in emmetropisation. When the eye is exposed to colour flicker the eye grows almost twice as much, and becomes more myopic, compared to when the eye is exposed to luminance flicker. Neural responses of the luminance and colour mechanisms direct accommodation and emmetropisation mechanisms to different focal planes. Therefore, it is likely that the set point of refraction and accommodation is dependent on the sensitivity of the eye to changes in spatial and temporal, colour and luminance contrast. Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Individual quality explains association between plumage colouration, arrival dates and mate acquisition in yellow warblers (Setophaga petechia).

PubMed

Jones, Teri B; Drake, Anna; Green, David J

2014-05-07

In many bird species colour traits influence social dominance and breeding success. In our study we first evaluated whether the colour of the basic plumage (tail feathers grown at the end of the breeding season), that provides an index of individual quality, influenced winter habitat use by yellow warblers. We then evaluated whether winter habitat use (inferred using δ13C and δ15N signatures of winter grown greater-coverts) influenced alternate plumage colouration, after controlling for individual quality using basic plumage colouration. Finally, we investigated whether basic and alternate plumage colouration influenced arrival dates, mate acquisition, breeding phenology and reproductive success of yellow warblers breeding in southern (Revelstoke, B.C.) and arctic (Inuvik, N.W.T.) Canada. The colour (chroma and hue) of tail feathers, grown on the breeding grounds, was not related to subsequent winter habitat use. Greater covert and tail feather colour (chroma and hue) were correlated, suggesting genetics and/or individual quality played a role in pigment deposition. After controlling for individual difference in tail colour, δ13C values did not explain any variation in greater covert colour, but birds with high δ15N signatures had greater coverts with higher chroma. Male arrival dates varied with tail chroma in Revelstoke and tail hue in Inuvik. Males that arrived early paired with older and/or more colourful mates that initiated clutches earlier, and at one site (Revelstoke) were more likely to fledge young. In addition, in Revelstoke (but not Inuvik) males with high tail hue also acquired more colourful mates. In contrast, after controlling for individual differences in tail colour, greater covert colour did not affect male arrival date, the quality of the mate obtained or reproductive success in either population. Our results suggest that plumage colour effects on breeding phenology and mate acquisition result from differences in the intrinsic quality of individuals rather than a carry-over effect of winter habitat use.

Individual quality explains association between plumage colouration, arrival dates and mate acquisition in yellow warblers (Setophaga petechia)

PubMed Central

2014-01-01

Background In many bird species colour traits influence social dominance and breeding success. In our study we first evaluated whether the colour of the basic plumage (tail feathers grown at the end of the breeding season), that provides an index of individual quality, influenced winter habitat use by yellow warblers. We then evaluated whether winter habitat use (inferred using δ13C and δ15N signatures of winter grown greater-coverts) influenced alternate plumage colouration, after controlling for individual quality using basic plumage colouration. Finally, we investigated whether basic and alternate plumage colouration influenced arrival dates, mate acquisition, breeding phenology and reproductive success of yellow warblers breeding in southern (Revelstoke, B.C.) and arctic (Inuvik, N.W.T.) Canada. Results The colour (chroma and hue) of tail feathers, grown on the breeding grounds, was not related to subsequent winter habitat use. Greater covert and tail feather colour (chroma and hue) were correlated, suggesting genetics and/or individual quality played a role in pigment deposition. After controlling for individual difference in tail colour, δ13C values did not explain any variation in greater covert colour, but birds with high δ15N signatures had greater coverts with higher chroma. Male arrival dates varied with tail chroma in Revelstoke and tail hue in Inuvik. Males that arrived early paired with older and/or more colourful mates that initiated clutches earlier, and at one site (Revelstoke) were more likely to fledge young. In addition, in Revelstoke (but not Inuvik) males with high tail hue also acquired more colourful mates. In contrast, after controlling for individual differences in tail colour, greater covert colour did not affect male arrival date, the quality of the mate obtained or reproductive success in either population. Conclusions Our results suggest that plumage colour effects on breeding phenology and mate acquisition result from differences in the intrinsic quality of individuals rather than a carry-over effect of winter habitat use. PMID:24886073

Poseidon's paintbox : historical archives of ocean colour in global-change perspective

NASA Astrophysics Data System (ADS)

Wernand, M. R.

2011-11-01

In the thesis introduction issues are discussed on the historical background of marine optics and on marine optical devices that were used over the past centuries to observe and measure; as in all sciences, in marine optics we can see a steady development: that of ‘measuring’, beginning many centuries ago, to 'knowing' and since less than a century to the understanding of the phenomenon. Hereafter, six themes are treated successively. The first theme, ‘Ocean optics from 1600 (Hudson) to 1930 (Raman), shift in interpretation of natural water colouring’, addresses the question of why it took so long a time to explain the phenomenon ‘the colouring of the sea’, especially the blue colour, despite the age-long interest of sailors, for practical purposes of navigation and detection of fish - of which more later. The second theme ‘On the history of the Secchi disc’, describes the search to establish methods for the determination of (sea) water clarity concerning purposes of navigation (near coast colour changes) just mentioned to detect shoals, and for a more basic purpose, tracing lost objects. The search to determine the clarity of lakes and seas culminated in the invention of the Secchi disc, used since the late 19th century. The third theme, ‘Spectral analysis of the Forel-Ule ocean colour comparator scale’, addresses the accuracy of a colour scale proposed, used in limnology and oceanography. Scale observations are put into perspective with contemporary measurements on the colour of the sea. The fourth theme, ‘Ocean colour changes in the North Pacific since 1930’, handles the question whether long-term ocean colour changes using historic Forel-Ule observations, in this part of the ocean made very frequently over time, can be determined in relation to global change. In principal global warming may cause a gradual change in ocean colour due to the effect of biological, chemical and physical aspects of the ocean-surface. The fifth theme, ‘MERIS-based ocean colour classification using the Forel-Ule scale’, addresses the question whether a relation can be established between the old Forel-Ule methodology, the classification of ocean colour by means of one of the scale colours, and the more recent satellite ocean colour methodology. The sixth theme, ‘Trends in ocean colour and chlorophyll concentration since 1889 to present’, addresses decadal colour changes per ocean and sea, using the longest available Forel-Ule dataset and confirms the possibility to transform these colour changes into chlorophyll concentration (indicative of the biomass of marine planktonic microalgae) changes. Such a transformation is needed to provide a link to the present in which chlorophyll concentrations are determined by using new technologies such as satellite remote sensing calibrated with high-performance liquid chromatography (HPLC) pigment analysis to determine marine microalgae pigments.

Yellow and the Novel Aposematic Signal, Red, Protect Delias Butterflies from Predators

PubMed Central

Wee, Jocelyn Liang Qi

2017-01-01

Butterflies of the South Asian and Australian genus Delias possess striking colours on the ventral wings that are presumed to serve as warning signals to predators. However, this has not been shown empirically. Here we experimentally tested whether the colours of one member of this diverse genus, Delias hyparete, function as aposematic signals. We constructed artificial paper models with either a faithful colour representation of D. hyparete, or with all of its colours converted to grey scale. We also produced models where single colours were left intact, while others were converted to grey-scale or removed entirely. We placed all model types simultaneously in the field, attached to a live mealworm, and measured relative attack rates at three separate field sites. Faithful models of D. hyparete, suffered the least amount of attacks, followed by grey-scale models with unaltered red patches, and by grey-scale models with unaltered yellow patches. We conclude that red and yellow colours function as warning signals. By mapping dorsal and ventral colouration onto a phylogeny of Delias, we observed that yellow and red colours appear almost exclusively on the ventral wing surfaces, and that basal lineages have mostly yellow, white, and black wings, whereas derived lineages contain red colour in addition to the other colours. Red appears to be, thus, a novel adaptive trait in this lineage of butterflies. PMID:28060944

Yellow and the Novel Aposematic Signal, Red, Protect Delias Butterflies from Predators.

PubMed

Wee, Jocelyn Liang Qi; Monteiro, Antónia

2017-01-01

Butterflies of the South Asian and Australian genus Delias possess striking colours on the ventral wings that are presumed to serve as warning signals to predators. However, this has not been shown empirically. Here we experimentally tested whether the colours of one member of this diverse genus, Delias hyparete, function as aposematic signals. We constructed artificial paper models with either a faithful colour representation of D. hyparete, or with all of its colours converted to grey scale. We also produced models where single colours were left intact, while others were converted to grey-scale or removed entirely. We placed all model types simultaneously in the field, attached to a live mealworm, and measured relative attack rates at three separate field sites. Faithful models of D. hyparete, suffered the least amount of attacks, followed by grey-scale models with unaltered red patches, and by grey-scale models with unaltered yellow patches. We conclude that red and yellow colours function as warning signals. By mapping dorsal and ventral colouration onto a phylogeny of Delias, we observed that yellow and red colours appear almost exclusively on the ventral wing surfaces, and that basal lineages have mostly yellow, white, and black wings, whereas derived lineages contain red colour in addition to the other colours. Red appears to be, thus, a novel adaptive trait in this lineage of butterflies.

Worldwide patterns of bird colouration on islands.

PubMed

Doutrelant, Claire; Paquet, Matthieu; Renoult, Julien P; Grégoire, Arnaud; Crochet, Pierre-André; Covas, Rita

2016-05-01

Island environments share distinctive characteristics that offer unique opportunities to investigate parallel evolution. Previous research has produced evidence of an island syndrome for morphological traits, life-history strategies and ecological niches, but little is known about the response to insularity of other important traits such as animal signals. Here, we tested whether birds' plumage colouration is part of the island syndrome. We analysed with spectrophotometry the colouration of 116 species endemic to islands and their 116 closest mainland relatives. We found a pattern of reduced brightness and colour intensity for both sexes on islands. In addition, we found a decrease in the number of colour patches on islands that, in males, was associated with a decrease in the number of same-family sympatric species. These results demonstrate a worldwide pattern of parallel colour changes on islands and suggest that a relaxation of selection on species recognition may be one of the mechanisms involved. © 2016 John Wiley & Sons Ltd/CNRS.

Capture by colour: evidence for dimension-specific singleton capture.

PubMed

Harris, Anthony M; Becker, Stefanie I; Remington, Roger W

2015-10-01

Previous work on attentional capture has shown the attentional system to be quite flexible in the stimulus properties it can be set to respond to. Several different attentional "modes" have been identified. Feature search mode allows attention to be set for specific features of a target (e.g., red). Singleton detection mode sets attention to respond to any discrepant item ("singleton") in the display. Relational search sets attention for the relative properties of the target in relation to the distractors (e.g., redder, larger). Recently, a new attentional mode was proposed that sets attention to respond to any singleton within a particular feature dimension (e.g., colour; Folk & Anderson, 2010). We tested this proposal against the predictions of previously established attentional modes. In a spatial cueing paradigm, participants searched for a colour target that was randomly either red or green. The nature of the attentional control setting was probed by presenting an irrelevant singleton cue prior to the target display and assessing whether it attracted attention. In all experiments, the cues were red, green, blue, or a white stimulus rapidly rotated (motion cue). The results of three experiments support the existence of a "colour singleton set," finding that all colour cues captured attention strongly, while motion cues captured attention only weakly or not at all. Notably, we also found that capture by motion cues in search for colour targets was moderated by their frequency; rare motion cues captured attention (weakly), while frequent motion cues did not.

Texture variations suppress suprathreshold brightness and colour variations.

PubMed

Schofield, Andrew J; Kingdom, Frederick A A

2014-01-01

Discriminating material changes from illumination changes is a key function of early vision. Luminance cues are ambiguous in this regard, but can be disambiguated by co-incident changes in colour and texture. Thus, colour and texture are likely to be given greater prominence than luminance for object segmentation, and better segmentation should in turn produce stronger grouping. We sought to measure the relative strengths of combined luminance, colour and texture contrast using a suprathreshhold, psychophysical grouping task. Stimuli comprised diagonal grids of circular patches bordered by a thin black line and contained combinations of luminance decrements with either violet, red, or texture increments. There were two tasks. In the Separate task the different cues were presented separately in a two-interval design, and participants indicated which interval contained the stronger orientation structure. In the Combined task the cues were combined to produce competing orientation structure in a single image. Participants had to indicate which orientation, and therefore which cue was dominant. Thus we established the relative grouping strength of each cue pair presented separately, and compared this to their relative grouping strength when combined. In this way we observed suprathreshold interactions between cues and were able to assess cue dominance at ecologically relevant signal levels. Participants required significantly more luminance and colour compared to texture contrast in the Combined compared to Separate conditions (contrast ratios differed by about 0.1 log units), showing that suprathreshold texture dominates colour and luminance when the different cues are presented in combination.

Iris colour, ethnic origin and progression of age-related macular degeneration.

PubMed

Nicolas, Caroline M; Robman, Luba D; Tikellis, Gabriella; Dimitrov, Peter N; Dowrick, Adam; Guymer, Robyn H; McCarty, Catherine A

2003-12-01

To investigate the relationship between iris colour, ethnic origin and the progression of age-related macular degeneration (AMD). Participants were recruited from the population-based Melbourne Visual Impairment Project or the prospective, randomized, double-masked Vitamin E, Cataract and Age-Related Macular Degeneration study. From these two cohorts, 171 participants aged between 52 and 93 years who were identified as having early AMD features at their baseline examination (1992-1995) were followed for an average of 6.8 years (until 2001) to determine the progression rate of early AMD. The participants' iris colour was categorized as light, intermediate or dark. Ethnic origin was categorized as Anglo-Saxon or non-Anglo-Saxon, according to the participants' grandparents' country of birth. In total, 53 (31%) of the 171 participants showed signs of AMD progression. Participants with light iris colour had twofold the risk of AMD progression of those with dark or intermediate iris colours, although the age-adjusted and multivariate-adjusted associations were not significant (both P = 0.13). Age-adjusted and multivariate comparisons of Anglo-Saxon ethnic origin to non-Anglo-Saxon ethnic origin showed a noticeable but non-significant association with progression of AMD (P= 0.22 and P= 0.14, respectively). Individuals with light iris colour or of Anglo-Saxon ethnic origin had a strong tendency to greater progression of AMD. A larger sample is required to confirm these clinically important, but statistically non-significant, associations.

Perception of Safety and Liking Associated to the Colour Intervention of Bike Lanes: Contribution from the Behavioural Sciences to Urban Design and Wellbeing

PubMed Central

Vera-Villarroel, Pablo; Contreras, Daniela; Lillo, Sebastián; Segovia, Ariel; Rojo, Natalia; Moreno, Sandra; Oyarzo, Francisco

2016-01-01

The perception of colour and its subjective effects are key issues to designing safe and enjoyable bike lanes. This paper addresses the relationship between the colours of bike lane interventions—in particular pavement painting and intersection design—and the subjective evaluation of liking, visual saliency, and perceived safety related to such an intervention. Utilising images of three real bike lane intersections modified by software to change their colour (five in total), this study recruited 538 participants to assess their perception of all fifteen colour-design combinations. A multivariate analysis of covariance (MANCOVA) with the Bonferroni post hoc test was performed to assess the effect of the main conditions (colour and design) on the dependent variables (liking towards the intervention, level of visual saliency of the intersection, and perceived safety of the bike lane). The results showed that the colour red was more positively associated to the outcome variables, followed by yellow and blue. Additionally, it was observed that the effect of colour widely outweighs the effect of design, suggesting that the right choice and use of colour would increase the effectiveness on bike-lanes pavement interventions. Limitations and future directions are discussed. PMID:27548562

Poor environmental tracking can make extinction risk insensitive to the colour of environmental noise

PubMed Central

van de Pol, Martijn; Vindenes, Yngvild; Sæther, Bernt-Erik; Engen, Steinar; Ens, Bruno J.; Oosterbeek, Kees; Tinbergen, Joost M.

2011-01-01

The relative importance of environmental colour for extinction risk compared with other aspects of environmental noise (mean and interannual variability) is poorly understood. Such knowledge is currently relevant, as climate change can cause the mean, variability and temporal autocorrelation of environmental variables to change. Here, we predict that the extinction risk of a shorebird population increases with the colour of a key environmental variable: winter temperature. However, the effect is weak compared with the impact of changes in the mean and interannual variability of temperature. Extinction risk was largely insensitive to noise colour, because demographic rates are poor in tracking the colour of the environment. We show that three mechanisms—which probably act in many species—can cause poor environmental tracking: (i) demographic rates that depend nonlinearly on environmental variables filter the noise colour, (ii) demographic rates typically depend on several environmental signals that do not change colour synchronously, and (iii) demographic stochasticity whitens the colour of demographic rates at low population size. We argue that the common practice of assuming perfect environmental tracking may result in overemphasizing the importance of noise colour for extinction risk. Consequently, ignoring environmental autocorrelation in population viability analysis could be less problematic than generally thought. PMID:21561978

Assessing the effects of UVA photocatalysis on soot-coated TiO2-containing mortars.

PubMed

De la Rosa, José M; Miller, Ana Z; Pozo-Antonio, J Santiago; González-Pérez, José A; Jiménez-Morillo, Nicasio T; Dionisio, Amelia

2017-12-15

The deposition of soot on building surfaces darkens their colour and leads to undesirable black crusts, which are one of the most serious problems on the conservation of built cultural heritage. As a preventive strategy, self-cleaning systems based on the use of titanium dioxide (TiO 2 ) coatings have been employed on building materials for degrading organic compounds deposited on building surfaces, improving their durability and performance. In this study, the self-cleaning effect of TiO 2 -containing mortars coated with diesel soot has been appraised under laboratory conditions. The mortar samples were manufactured using lime putty and two different doses of TiO 2 (2.5% and 5%). The lime mortars were then coated with diesel engine soot and irradiated with ultraviolet A (UVA) illumination for 30days. The photocatalytic efficiency was evaluated by visual inspection, field emission scanning electron microscopy (FESEM) and colour spectrophotometry. Changes in the chemical composition of the soot particles (including persistent organic pollutants) were assessed by analytical pyrolysis (Py-GC/MS) and solid state 13 C NMR spectroscopy. The FESEM and colour spectrophotometry revealed that the soot-coated TiO 2 -containing mortars promoted a self-cleaning effect after UVA irradiation. The combination of analytical pyrolysis and 13 C solid state NMR showed that the UVA irradiation caused the cracking of polycyclic aromatic structures and n-alkyl compounds of the diesel soot and its transformation into methyl polymers. Our findings also revealed that the inclusion of TiO 2 in the lime mortar formulations catalysed these transformations promoting the self-cleaning of the soot-stained mortars. The combined action of TiO 2 and UVA irradiation is a promising proxy to clean lime mortars affected by soot deposition. Copyright © 2017 Elsevier B.V. All rights reserved.

Apparent optical properties of the Canadian Beaufort Sea - Part 1: Observational overview and water column relationships

NASA Astrophysics Data System (ADS)

Antoine, D.; Hooker, S. B.; Belanger, S.; Matsuoka, A.; Babin, M.

2013-03-01

A data set of radiometric measurements collected in the Beaufort Sea (Canadian Arctic) in August 2009 (MALINA project) is analysed in order to describe apparent optical properties (AOPs) in this sea, which is subject to dramatic environmental changes for several decades. The two properties derived from the measurements are the spectral diffuse attenuation coefficient for downward irradiance, Kd, and the spectral remote sensing reflectance, Rrs. The former controls light propagation in the upper water column. The latter determines how light is backscattered out of the water and becomes eventually observable from a satellite ocean colour sensor. The data set includes offshore clear waters of the Beaufort basin as well as highly turbid waters of the Mackenzie River plumes. In the clear waters, we show Kd values that are much larger in the ultraviolet and blue parts of the spectrum than what could be anticipated considering the chlorophyll concentration. A larger contribution of absorption by coloured dissolved organic matter (CDOM) is responsible for this high Kd values, as compared to other oligotrophic areas. In turbid waters, attenuation reaches extremely high values, driven by high loads of particulate materials and also by a large CDOM content. In these two extreme types of waters, current satellite chlorophyll algorithms fail. This is questioning the role of ocean colour remote sensing in the Arctic when Rrs from only the blue and green bands are used. Therefore, other parts of the spectrum (e.g. the red) should be explored if one aims at quantifying interannual changes in chlorophyll in the Arctic from space. The very peculiar AOPs in the Beaufort Sea also advocate for developing specific light propagation models when attempting to predict light availability for photosynthesis at depth.

The 2-degree Field Lensing Survey: photometric redshifts from a large new training sample to r < 19.5

NASA Astrophysics Data System (ADS)

Wolf, C.; Johnson, A. S.; Bilicki, M.; Blake, C.; Amon, A.; Erben, T.; Glazebrook, K.; Heymans, C.; Hildebrandt, H.; Joudaki, S.; Klaes, D.; Kuijken, K.; Lidman, C.; Marin, F.; Parkinson, D.; Poole, G.

2017-04-01

We present a new training set for estimating empirical photometric redshifts of galaxies, which was created as part of the 2-degree Field Lensing Survey project. This training set is located in a ˜700 deg2 area of the Kilo-Degree-Survey South field and is randomly selected and nearly complete at r < 19.5. We investigate the photometric redshift performance obtained with ugriz photometry from VST-ATLAS and W1/W2 from WISE, based on several empirical and template methods. The best redshift errors are obtained with kernel-density estimation (KDE), as are the lowest biases, which are consistent with zero within statistical noise. The 68th percentiles of the redshift scatter for magnitude-limited samples at r < (15.5, 17.5, 19.5) are (0.014, 0.017, 0.028). In this magnitude range, there are no known ambiguities in the colour-redshift map, consistent with a small rate of redshift outliers. In the fainter regime, the KDE method produces p(z) estimates per galaxy that represent unbiased and accurate redshift frequency expectations. The p(z) sum over any subsample is consistent with the true redshift frequency plus Poisson noise. Further improvements in redshift precision at r < 20 would mostly be expected from filter sets with narrower passbands to increase the sensitivity of colours to small changes in redshift.

Stars caught in the braking stage in young Magellanic Cloud clusters

NASA Astrophysics Data System (ADS)

D'Antona, Francesca; Milone, Antonino P.; Tailo, Marco; Ventura, Paolo; Vesperini, Enrico; di Criscienzo, Marcella

2017-08-01

The colour-magnitude diagrams of many Magellanic Cloud clusters (with ages up to 2 billion years) display extended turnoff regions where the stars leave the main sequence, suggesting the presence of multiple stellar populations with ages that may differ even by hundreds of millions of years 1,2,3 . A strongly debated question is whether such an extended turnoff is instead due to populations with different stellar rotations3,4,5,6 . The recent discovery of a 'split' main sequence in some younger clusters (~80-400 Myr) added another piece to this puzzle. The blue side of the main sequence is consistent with slowly rotating stellar models, and the red side consistent with rapidly rotating models7,8,9,10. However, a complete theoretical characterization of the observed colour-magnitude diagram also seemed to require an age spread9. We show here that, in the three clusters so far analysed, if the blue main-sequence stars are interpreted with models in which the stars have always been slowly rotating, they must be ~30% younger than the rest of the cluster. If they are instead interpreted as stars that were initially rapidly rotating but have later slowed down, the age difference disappears, and this 'braking' also helps to explain the apparent age differences of the extended turnoff. The age spreads in Magellanic Cloud clusters are thus a manifestation of rotational stellar evolution. Observational tests are suggested.

Viability selection affects black but not yellow plumage colour in greenfinches.

PubMed

Hõrak, Peeter; Männiste, Marju

2016-01-01

Much of the debate surrounding the selective forces responsible for the expression of conspicuous plumage colouration is centred on the question of precisely which individual qualities are signalled by carotenoid- and melanin-based pigments. To examine this and other related issues, we performed viability selection analyses in wild-caught captive male greenfinches (Carduelis chloris) in Estonia during winters between 2003 and 2014. Based on our measurements, birds with a darker black eumelanin-based colouration of tail feathers survived better than those whose tail feathers had a paler black colouration. The carotenoid-based yellow colouration of the same feathers was not associated with mortality in captivity and showed much less between-year variation in the field than the black colouration. Between year-variation in the black (but not yellow) colouration of feathers was parallel in wild-grown feathers (on birds in the wild) and laboratory-grown ones (on birds held temporarily in captivity). Taken together, these findings imply that eumelanotic colouration in greenfinches is currently under selection and suggest the presence of sufficient genetic variation for a rapid response to selection. In particular, tail feathers have become darker black since the emergence of avian trichomonosis, which is known to selectively kill paler individuals.

["One makes a distinction between 2 color contrasts, the instantaneous and the afterimage". Several color theory comments by Gottfried Semper in the "style" of 1860].

PubMed

Rehm, Robin

2010-01-01

Gottfried Semper (1803-1879) is well-known for his work on colour schemes in architecture. The architect published several books and articles on related topics, such as polychromy in Greek and Roman edifices, mural paintings of Pompeii, and the colouring of the renaissance architecture. It has been less discussed, however, that Semper was also engaged in the contemporary discourse on colour theory as pursued in Natural Science research. The paper examines theoretical remarks on colour in Semper's publication "Der Stil" of 1860. His terminology, the modality of his explanations and his discussion of colour experiments suggest that Semper was familiar with Michel-Eugène Chevreul's theory of colour. Semper's reception of Chevreul is not surprising. The French chemist wrote one of the most important studies of colour of the nineteenth century. His famous book "De la loi du contraste simultané des couleurs" was published in Paris in 1839, where he developed some of the principles of "harmony and contrast of colours" and their application to the arts. Especially Chevreul's synthesis between theoretical consolidation and practical transformation seem to have attracted Semper's attention.

Temperature dependence and P/Ti ratio in phosphoric acid treatment of titanium dioxide and powder properties.

PubMed

Onoda, H; Matsukura, A

2015-02-01

Titanium dioxide has photocatalytic activity and is used as a white pigment for cosmetics. A certain degree of sebum on the skin is decomposed by the ultraviolet radiation in sunlight. In this work, titanium dioxide was shaken with phosphoric acid to synthesize a white pigment for cosmetics. Titanium dioxide was treated with 0.1 mol/L of phosphoric acid at various P/Ti molar ratios, and then shaken in hot water for 1 h. The chemical composition, powder properties, photocatalytic activity, colour phase, and smoothness of the obtained powder were studied. The obtained materials indicated XRD peaks of titanium dioxide, however the peaks diminished subsequent to phosphoric acid treatment. The samples included small particles with sub-micrometer size. The photocatalytic activity of the obtained powders decreased, decomposing less sebum on the skin. Samples prepared at high P/Ti ratio with high shaking temperature indicated low whiteness in in L*a*b* colour space. The shaking and heating temperature and P/Ti ratio had influence on the smoothness of the obtained materials. Phosphoric acid treatment of titanium dioxide is an effective method to inhibit photocatalytic activity for a white pigment. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Comparative Analysis of the Properties of Acid-Base Indicator of Rose (Rosa setigera), Allamanda (Allamanda cathartica), and Hibiscus (Hibiscus rosa-sinensis) Flowers

PubMed Central

Okoduwa, Stanley I. R.; Mbora, Lovina O.; Adu, Matthew E.; Adeyi, Ameh A.

2015-01-01

The need to develop effective alternative for synthetic indicators is the demand of present-day chemistry. The acid-base indicator properties of Rose (Rosa setigera), Allamanda (Allamanda cathartica), and Hibiscus (Hibiscus rosa-sinensis) flowers were examined. Colour pigments were extracted from the flowers via cold and solvent extraction using soxhlet extractor. The pH value of the extracts with wavelengths of absorption was determined using ultraviolet spectrophotometer. From the results obtained, all the extracts exhibited sharp contrast between their colours in acid and base. Their pH was found to be 5.5 for cold extract of Rose and 5.6 for solvent extraction, 5.24 for cold extract of a Hibiscus and 6.52 for solvent extraction, 5.35 for cold extract of Allamanda, and 5.45 for solvent extraction. The maximum wavelengths of absorption obtained for all the extract fall within the visible region of electromagnetic spectrum. These values are almost similar to that obtained from synthetic indicators. It is on these bases that we concluded that natural indicators could be an excellent replacement for synthetic indicators since they are cheap, readily available, simple to extract, not toxic, user and environmentally friendly. PMID:26819757

The impact of skin colour on human photobiological responses.

PubMed

Fajuyigbe, Damilola; Young, Antony R

2016-11-01

Terrestrial solar ultraviolet radiation (UVR) exerts both beneficial and adverse effects on human skin. Epidemiological studies show a lower incidence of skin cancer in people with pigmented skins compared to fair skins. This is attributed to photoprotection by epidermal melanin, as is the poorer vitamin D status of those with darker skins. We summarize a wide range of photobiological responses across different skin colours including DNA damage and immunosuppression. Some studies show the generally modest photoprotective properties of melanin, but others show little or no effect. DNA photodamage initiates non-melanoma skin cancer and is reduced by a factor of about 3 in pigmented skin compared with white skin. This suggests that if such a modest reduction in DNA damage can result in the significantly lower skin cancer incidence in black skin, the use of sunscreen protection might be extremely beneficial for susceptible population. Many contradictory results may be explained by protocol differences, including differences in UVR spectra and exposure protocols. We recommend that skin type comparisons be done with solar-simulated radiation and standard erythema doses or physical doses (J/m 2 ) rather than those based solely on clinical endpoints such as minimal erythema dose (MED). © 2016 The Authors. Pigment Cell & Melanoma Research Published by John Wiley & Sons Ltd.

The long goodbye

NASA Image and Video Library

2015-07-27

A dying star’s final moments are captured in this image from the NASA/ESA Hubble Space Telescope. The death throes of this star may only last mere moments on a cosmological timescale, but this star’s demise is still quite lengthy by our standards, lasting tens of thousands of years! The star’s agony has culminated in a wonderful planetary nebula known as NGC 6565, a cloud of gas that was ejected from the star after strong stellar winds pushed the star’s outer layers away into space. Once enough material was ejected, the star’s luminous core was exposed and it began to produce ultraviolet radiation, exciting the surrounding gas to varying degrees and causing it to radiate in an attractive array of colours. These same colours can be seen in the famous and impressive Ring Nebula (heic1310), a prominent example of a nebula like this one. Planetary nebulae are illuminated for around 10 000 years before the central star begins to cool and shrink to become a white dwarf. When this happens, the star’s light drastically diminishes and ceases to excite the surrounding gas, so the nebula fades from view. A version of this image was entered into the Hubble’s Hidden Treasures basic image competition by contestant Matej Novak.

High sensitivity to short wavelengths in a lizard and implications for understanding the evolution of visual systems in lizards

PubMed Central

Fleishman, Leo J.; Loew, Ellis R.; Whiting, Martin J.

2011-01-01

Progress in developing animal communication theory is frequently constrained by a poor understanding of sensory systems. For example, while lizards have been the focus of numerous studies in visual signalling, we only have data on the spectral sensitivities of a few species clustered in two major clades (Iguania and Gekkota). Using electroretinography and microspectrophotometry, we studied the visual system of the cordylid lizard Platysaurus broadleyi because it represents an unstudied clade (Scinciformata) with respect to visual systems and because UV signals feature prominently in its social behaviour. The retina possessed four classes of single and one class of double cones. Sensitivity in the ultraviolet region (UV) was approximately three times higher than previously reported for other lizards. We found more colourless oil droplets (associated with UV-sensitive (UVS) and short wavelength-sensitive (SWS) photoreceptors), suggesting that the increased sensitivity was owing to the presence of more UVS photoreceptors. Using the Vorobyev–Osorio colour discrimination model, we demonstrated that an increase in the number of UVS photoreceptors significantly enhances a lizard's ability to discriminate conspecific male throat colours. Visual systems in diurnal lizards appear to be broadly conserved, but data from additional clades are needed to confirm this. PMID:21389031

Paper un-printing: using lasers to remove toner-print in order to reuse office paper

NASA Astrophysics Data System (ADS)

Leal-Ayala, D. R.; Allwood, J. M.; Counsell, T. A. M.

2011-12-01

In this article, lasers in the ultraviolet, visible and infrared light spectra working with pulse widths in the nanosecond range are applied to a range of toner-paper combinations to determine their ability to remove toner. If the laser energy fluence can be chosen to stay below the ablation threshold of paper at the same time that it surpasses that of toner, paper could be cleaned and re-used instead of being recycled or disposed into a landfill. This could significantly reduce the environmental impact of paper production and use. Although there are a variety of paper conservation studies which have investigated the effects of laser radiation on blank and soiled paper, none has previously explored toner-print removal from paper by laser ablation. Colour analysis under the L ∗ a ∗ b ∗ colour space and SEM examination of the outcome indicate that it is possible to remove toner from paper without damaging and discolouring the substrate. Best results are obtained when employing visible radiation at a wavelength of 532 nm working with a pulse width of 4 ns and energy fluences under 1.6 J/cm2. This means that it is technically feasible to remove toner-print for paper re-use.

Spectral Diversity and Regulation of Coral Fluorescence in a Mesophotic Reef Habitat in the Red Sea

PubMed Central

Eyal, Gal; Wiedenmann, Jörg; Grinblat, Mila; D’Angelo, Cecilia; Kramarsky-Winter, Esti; Treibitz, Tali; Ben-Zvi, Or; Shaked, Yonathan; Smith, Tyler B.; Harii, Saki; Denis, Vianney; Noyes, Tim; Tamir, Raz; Loya, Yossi

2015-01-01

The phenomenon of coral fluorescence in mesophotic reefs, although well described for shallow waters, remains largely unstudied. We found that representatives of many scleractinian species are brightly fluorescent at depths of 50–60 m at the Interuniversity Institute for Marine Sciences (IUI) reef in Eilat, Israel. Some of these fluorescent species have distribution maxima at mesophotic depths (40–100 m). Several individuals from these depths displayed yellow or orange-red fluorescence, the latter being essentially absent in corals from the shallowest parts of this reef. We demonstrate experimentally that in some cases the production of fluorescent pigments is independent of the exposure to light; while in others, the fluorescence signature is altered or lost when the animals are kept in darkness. Furthermore, we show that green-to-red photoconversion of fluorescent pigments mediated by short-wavelength light can occur also at depths where ultraviolet wavelengths are absent from the underwater light field. Intraspecific colour polymorphisms regarding the colour of the tissue fluorescence, common among shallow water corals, were also observed for mesophotic species. Our results suggest that fluorescent pigments in mesophotic reefs fulfil a distinct biological function and offer promising application potential for coral-reef monitoring and biomedical imaging. PMID:26107282

Purification and properties of pyrazon dioxygenase from pyrazon-degrading bacteria.

PubMed

Sauber, K; Fröhner, C; Rosenberg, G; Eberspächer, J; Lingens, F

1977-03-15

Chromatography on DEAE-cellulose and gel filtration on Sephadex revealed that pyrazon dioxygenase from pyrazon-degrading bacteria consists of three different enzyme components. No component alone oxidizes the phenyl moiety of pyrazon, only when the three components are combined can oxidation be detected. Following electron paramagnetic resonance and ultraviolet measurements the protein nature of the three components was determined: component A1 (molecular weight about 180000,red-brown in colour) is an iron-sulphur protein. The existence of approximately two moles of iron and two moles of inorganic sulphur per mole of protein was demonstrated. This enzyme component was purified to homogeneity in disc electrophoresis. Component A2 is a yellow protein of a molecular weight of about 67000. FAD was shown to be the prosthetic group of this protein. Component B (molecular weight about 12000, brown in colour) is a protein of the ferredoxin type, which was purified to homogeneity, as demonstrated by disc electrophoresis. A hypothetical scheme for the cooperation of the three components is proposed: component A2 accepts as cosubstrate NADH and functions as a ferredoxin reductase. The ferredoxin, component B, has the function of an electron carrier. The conversion of the substrates is effected by component A1, the terminal dioxygenase.

Tuning the white light spectrum of light emitting diode lamps to reduce attraction of nocturnal arthropods

PubMed Central

Longcore, Travis; Aldern, Hannah L.; Eggers, John F.; Flores, Steve; Franco, Lesly; Hirshfield-Yamanishi, Eric; Petrinec, Laina N.; Yan, Wilson A.; Barroso, André M.

2015-01-01

Artificial lighting allows humans to be active at night, but has many unintended consequences, including interference with ecological processes, disruption of circadian rhythms and increased exposure to insect vectors of diseases. Although ultraviolet and blue light are usually most attractive to arthropods, degree of attraction varies among orders. With a focus on future indoor lighting applications, we manipulated the spectrum of white lamps to investigate the influence of spectral composition on number of arthropods attracted. We compared numbers of arthropods captured at three customizable light-emitting diode (LED) lamps (3510, 2704 and 2728 K), two commercial LED lamps (2700 K), two commercial compact fluorescent lamps (CFLs; 2700 K) and a control. We configured the three custom LEDs to minimize invertebrate attraction based on published attraction curves for honeybees and moths. Lamps were placed with pan traps at an urban and two rural study sites in Los Angeles, California. For all invertebrate orders combined, our custom LED configurations were less attractive than the commercial LED lamps or CFLs of similar colour temperatures. Thus, adjusting spectral composition of white light to minimize attracting nocturnal arthropods is feasible; not all lights with the same colour temperature are equally attractive to arthropods. PMID:25780237

Ultraviolet Rayleigh Scatter Imaging for Spatial Temperature Profiles in Atmospheric Microdischarges

DTIC Science & Technology

2014-09-01

regime and not in a neighboring regime such as an abnormal glow or a corona discharge . As discussed in section 3.1, unlike abnormal discharges or... coronas , normal glows have a voltage drop that is independent of discharge current for several orders of magnitude, which would manifest itself...5 3.2 Discharge Power and Gas Temperature

Interaction between numbers and size during visual search.

PubMed

Krause, Florian; Bekkering, Harold; Pratt, Jay; Lindemann, Oliver

2017-05-01

The current study investigates an interaction between numbers and physical size (i.e. size congruity) in visual search. In three experiments, participants had to detect a physically large (or small) target item among physically small (or large) distractors in a search task comprising single-digit numbers. The relative numerical size of the digits was varied, such that the target item was either among the numerically large or small numbers in the search display and the relation between numerical and physical size was either congruent or incongruent. Perceptual differences of the stimuli were controlled by a condition in which participants had to search for a differently coloured target item with the same physical size and by the usage of LCD-style numbers that were matched in visual similarity by shape transformations. The results of all three experiments consistently revealed that detecting a physically large target item is significantly faster when the numerical size of the target item is large as well (congruent), compared to when it is small (incongruent). This novel finding of a size congruity effect in visual search demonstrates an interaction between numerical and physical size in an experimental setting beyond typically used binary comparison tasks, and provides important new evidence for the notion of shared cognitive codes for numbers and sensorimotor magnitudes. Theoretical consequences for recent models on attention, magnitude representation and their interactions are discussed.

Interstellar matter in Shapley-Ames elliptical galaxies. IV. A diffusely distributed component of dust and its effect on colour gradients.

NASA Astrophysics Data System (ADS)

Goudfrooij, P.; de Jong, T.

1995-06-01

We have investigated IRAS far-infrared observations of a complete, blue magnitude limited sample of 56 elliptical galaxies selected from the Revised Shapley-Ames Catalog. Data from a homogeneous optical CCD imaging survey as well as published X-ray data from the EINSTEIN satellite are used to constrain the infrared data. Dust masses as determined from the IRAS flux densities are found to be roughly an order of magnitude higher than those determined from optical extinction values of dust lanes and patches, in strong contrast with the situation in spiral galaxies. This "mass discrepancy" is found to be independent of the (apparent) inclination of the dust lanes. To resolve this dilemma we postulate that the majority of the dust in elliptical galaxies exists as a diffusely distributed component of dust which is undetectable at optical wavelengths. Using observed radial optical surface brightness profiles, we have systematically investigated possible heating mechanisms for the dust within elliptical galaxies. We find that heating of the dust in elliptical galaxies by the interstellar radiation field is generally sufficient to account for the dust temperatures as indicated by the IRAS flux densities. Collisions of dust grains with hot electrons in elliptical galaxies which are embedded in a hot, X-ray-emitting gas is found to be another effective heating mechanism for the dust. Employing model calculations which involve the transfer of stellar radiation in a spherical distribution of stars mixed with a diffuse distribution of dust, we show that the observed infrared luminosities imply total dust optical depths of the postulated diffusely distributed dust component in the range 0.1<~τ_V_<~0.7 and radial colour gradients 0.03<~{DELTA}(B-I)/{DELTA}log r<~0.25. The observed IRAS flux densities can be reproduced within the 1σ uncertainties in virtually all ellipticals in this sample by this newly postulated dust component, diffusely distributed over the inner few kpc of the galaxies, and heated by optical photons and/or hot electrons. The radial colour gradients implied by the diffuse dust component are found to be smaller than or equal to the observed colour gradients. Thus, we argue that the effect of dust extinction should be taken seriously in the interpretation of colour gradients in elliptical galaxies. We show that the amount of dust observed in luminous elliptical galaxies is generally higher than that expected from production by mass loss of stars within elliptical galaxies and destruction by sputtering in hot gas. This suggests that most of the dust in elliptical galaxies generally has an external origin.

Isolation and cDNA cloning of a novel red colour-related pigment-binding protein derived from the shell of the shrimp, Litopenaeus vannamei.

PubMed

Pan, Chuang; Ishizaki, Shoichiro; Nagashima, Yuji; Gao, Jialong; Watabe, Shugo

2018-02-15

Pigment-binding proteins play important roles in crustacean shell colour change. In this study, a red colour-related pigment-binding protein, designated LvPBP75, was purified from the shell of Litopenaeus vannamei. HPLC and PAGE analysis showed that LvPBP75 was a homogeneous monomer with molecular mass of 75kDa. Peptide mass fingerprint analysis revealed that LvPBP75 belonged to hemocyanin, and the released pigment from heated LvPBP75 showed a λ max at 481nm in acetone. The significant red-colour change temperatures were detected at 30 and 80°C, respectively. Based on the determined amino acid fragments, a full-length cDNA of LvPBP75 was cloned and sequenced. The ORF encodes a protein of 662 amino acids having 80% identity with penaeidae hemocyanin. These results strongly suggest a novel function of hemocyanin, namely binding with pigment, and its involvement in L. vannamei shell colour change. Copyright © 2017 Elsevier Ltd. All rights reserved.

Does infrared or ultraviolet light damage the lens?

PubMed Central

Söderberg, P G; Talebizadeh, N; Yu, Z; Galichanin, K

2016-01-01

In daylight, the human eye is exposed to long wavelength ultraviolet radiation (UVR), visible radiation and short wavelength infrared radiation (IRR). Almost all the UVR and a fraction of the IRR waveband, respectively, left over after attenuation in the cornea, is absorbed in the lens. The time delay between exposure and onset of biological response in the lens varies from immediate-to-short-to-late. After exposure to sunlight or artificial sources, generating irradiances of the same order of magnitude or slightly higher, biological damage may occur photochemically or thermally. Epidemiological studies suggest a dose-dependent association between short wavelength UVR and cortical cataract. Experimental data infer that repeated daily in vivo exposures to short wavelength UVR generate photochemically induced damage in the lens, and that short delay onset cataract after UVR exposure is photochemically induced. Epidemiology suggests that daily high-intensity short wavelength IRR exposure of workers, is associated with a higher prevalence of age-related cataract. It cannot be excluded that this effect is owing to a thermally induced higher denaturation rate. Recent experimental data rule out a photochemical effect of 1090 nm in the lens but other wavelengths in the near IRR should be investigated. PMID:26768915

The Effect of the Type and Colour of Placebo Stimuli on Placebo Effects Induced by Observational Learning.

PubMed

Świder, Karolina; Bąbel, Przemysław

2016-01-01

Research shows that placebo analgesia and nocebo hyperalgesia can be induced through observational learning. Our aim was to replicate and extend these results by studying the influence of the type and colour of stimuli used as placebos on the placebo effects induced by observational learning. Three experimental and two control groups were tested. All participants received pain stimuli of the same intensity preceded by colour lights (green and red) or geometric shapes (circles and squares). Before receiving pain stimuli, participants in the experimental groups, but not in the control groups, observed a model who rated pain stimuli that were preceded by either green lights (green placebo group), red lights (red placebo group), or circles (circle placebo group) as being less painful than those preceded by either red lights (green placebo group), green lights (red placebo group), or squares (circle placebo group). As a result participants in the experimental groups rated pain stimuli preceded by either green lights (green placebo group), red lights (red placebo group), or circles (circle placebo group) as being less painful than the participants in the control groups did, indicating that placebo effect was induced. No statistically significant differences were found in the magnitudes of the placebo effects between the three experimental groups (green placebo, red placebo, and circle placebo groups), indicating that neither the type nor the colour of placebo stimuli affected the placebo effects induced by observational learning. The placebo effects induced by observational learning were found to be unrelated to the individual differences in pain anxiety, fear of pain, and empathy.

The Effect of the Type and Colour of Placebo Stimuli on Placebo Effects Induced by Observational Learning

PubMed Central

Świder, Karolina; Bąbel, Przemysław

2016-01-01

Research shows that placebo analgesia and nocebo hyperalgesia can be induced through observational learning. Our aim was to replicate and extend these results by studying the influence of the type and colour of stimuli used as placebos on the placebo effects induced by observational learning. Three experimental and two control groups were tested. All participants received pain stimuli of the same intensity preceded by colour lights (green and red) or geometric shapes (circles and squares). Before receiving pain stimuli, participants in the experimental groups, but not in the control groups, observed a model who rated pain stimuli that were preceded by either green lights (green placebo group), red lights (red placebo group), or circles (circle placebo group) as being less painful than those preceded by either red lights (green placebo group), green lights (red placebo group), or squares (circle placebo group). As a result participants in the experimental groups rated pain stimuli preceded by either green lights (green placebo group), red lights (red placebo group), or circles (circle placebo group) as being less painful than the participants in the control groups did, indicating that placebo effect was induced. No statistically significant differences were found in the magnitudes of the placebo effects between the three experimental groups (green placebo, red placebo, and circle placebo groups), indicating that neither the type nor the colour of placebo stimuli affected the placebo effects induced by observational learning. The placebo effects induced by observational learning were found to be unrelated to the individual differences in pain anxiety, fear of pain, and empathy. PMID:27362552

Development and validation of a questionnaire assessing the quality of life impact of Colour Blindness (CBQoL).

PubMed

Barry, John A; Mollan, Susan; Burdon, Michael A; Jenkins, Michelle; Denniston, Alastair K

2017-10-02

Congenital colour vision deficiency (CVD), commonly called 'colour blindness', affects around 8% of men and 0.4% of women. Although many aspects of health (e.g. change in colour of urine) and healthcare (e.g. coloured medication, colour-coded diagnostic tests), and modern life depend upon colour coding (e.g. graphs, maps, signals), the impact of colour blindness on everyday life is not generally considered a topic of importance. This study is the first to create and validate a questionnaire measuring the quality of life (QoL) impact of being colour blind. This study consisted of two phases. Firstly, the questionnaire design and development phase was led by an expert panel and piloted on a focus group. Secondly, an online sample of 128 men and 291 women filled in the questionnaire, and the psychometric properties of the questionnaire were analysed using principal components analysis (PCA). The scores of colour blind (CB) participants and normal-sighted controls, controlling for age and sex, were compared using matched t-tests. The PCA resulted in a questionnaire with three domains (or subscales): QoL for Health & Lifestyle, QoL for Work, and QoL for Emotions. Controlling for age, there was a significantly greater negative impact on QoL for CB people than normal-sighted controls in regards to confusion over colour in various aspects of their health (p = 5 × 10 -7 ), work (p = 1.3 × 10 -7 ), and emotional life (p = 6 × 10 -5 ). Colour blindness can significantly impact quality of life for health, emotions, and especially careers. The tool developed here could be useful in future clinical studies to measure changes in CBQoL in response to therapy in conditions where colour vision is affected. We also discuss ways in which everyday problems related to colour vision might be reduced, for example, workplaces could avoid colour coding where a non-colour alternative is possible.

HAZMAT. II. Ultraviolet Variability of Low-mass Stars in the GALEX Archive

NASA Astrophysics Data System (ADS)

Miles, Brittany E.; Shkolnik, Evgenya L.

2017-08-01

The ultraviolet (UV) light from a host star influences a planet’s atmospheric photochemistry and will affect interpretations of exoplanetary spectra from future missions like the James Webb Space Telescope. These effects will be particularly critical in the study of planetary atmospheres around M dwarfs, including Earth-sized planets in the habitable zone. Given the higher activity levels of M dwarfs compared to Sun-like stars, time-resolved UV data are needed for more accurate input conditions for exoplanet atmospheric modeling. The Galaxy Evolution Explorer (GALEX) provides multi-epoch photometric observations in two UV bands: near-ultraviolet (NUV; 1771-2831 Å) and far-ultraviolet (FUV; 1344-1786 Å). Within 30 pc of Earth, there are 357 and 303 M dwarfs in the NUV and FUV bands, respectively, with multiple GALEX observations. Simultaneous NUV and FUV detections exist for 145 stars in both GALEX bands. Our analyses of these data show that low-mass stars are typically more variable in the FUV than the NUV. Median variability increases with later spectral types in the NUV with no clear trend in the FUV. We find evidence that flares increase the FUV flux density far more than the NUV flux density, leading to variable FUV to NUV flux density ratios in the GALEX bandpasses.The ratio of FUV to NUV flux is important for interpreting the presence of atmospheric molecules in planetary atmospheres such as oxygen and methane as a high FUV to NUV ratio may cause false-positive biosignature detections. This ratio of flux density in the GALEX bands spans three orders of magnitude in our sample, from 0.008 to 4.6, and is 1 to 2 orders of magnitude higher than for G dwarfs like the Sun. These results characterize the UV behavior for the largest set of low-mass stars to date.

HAZMAT. II. Ultraviolet Variability of Low-mass Stars in the GALEX Archive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miles, Brittany E.; Shkolnik, Evgenya L., E-mail: bmiles@ucsc.edu

The ultraviolet (UV) light from a host star influences a planet’s atmospheric photochemistry and will affect interpretations of exoplanetary spectra from future missions like the James Webb Space Telescope . These effects will be particularly critical in the study of planetary atmospheres around M dwarfs, including Earth-sized planets in the habitable zone. Given the higher activity levels of M dwarfs compared to Sun-like stars, time-resolved UV data are needed for more accurate input conditions for exoplanet atmospheric modeling. The Galaxy Evolution Explorer ( GALEX ) provides multi-epoch photometric observations in two UV bands: near-ultraviolet (NUV; 1771–2831 Å) and far-ultraviolet (FUV;more » 1344–1786 Å). Within 30 pc of Earth, there are 357 and 303 M dwarfs in the NUV and FUV bands, respectively, with multiple GALEX observations. Simultaneous NUV and FUV detections exist for 145 stars in both GALEX bands. Our analyses of these data show that low-mass stars are typically more variable in the FUV than the NUV. Median variability increases with later spectral types in the NUV with no clear trend in the FUV. We find evidence that flares increase the FUV flux density far more than the NUV flux density, leading to variable FUV to NUV flux density ratios in the GALEX bandpasses.The ratio of FUV to NUV flux is important for interpreting the presence of atmospheric molecules in planetary atmospheres such as oxygen and methane as a high FUV to NUV ratio may cause false-positive biosignature detections. This ratio of flux density in the GALEX bands spans three orders of magnitude in our sample, from 0.008 to 4.6, and is 1 to 2 orders of magnitude higher than for G dwarfs like the Sun. These results characterize the UV behavior for the largest set of low-mass stars to date.« less

Drawing ability in typical and atypical development; colour cues and the effect of oblique lines.

PubMed

Farran, E K; Dodd, G F

2015-06-01

Individuals with Williams syndrome (WS) have poor drawing ability. Here, we investigated whether colour could be used as a facilitation cue during a drawing task. Participants with WS and non-verbal ability matched typically developing (TD) children were shown line figures presented on a 3 by 3 dot matrix, and asked to replicate the figures by drawing on an empty dot matrix. The dots of the matrix were either all black (control condition), or nine different coloured dots (colour condition). In a third condition, which also used coloured dots, participants were additionally asked to verbalise the colours of the dots prior to replicating the line drawings (colour-verbal condition). Performance was stronger in both WS and TD groups on the two coloured conditions, compared with the control condition. However, the facilitation effect of colour was significantly weaker in the WS group than in the TD group. Replication of oblique line segments was less successful than replication of non-oblique line segments for both groups; this effect was reduced by colour facilitation in the TD group only. Verbalising the colours had no additional impact on performance in either group. We suggest that colour acted as a cue to individuate the dots, thus enabling participants to better ascertain the spatial relationships between the parts of each figure, to determine the start and end points of component lines, and to determine the correspondence between the model and their replication. The reduced facilitation in the WS group is discussed in relation to the effect of oblique versus non-oblique lines, the use of atypical drawing strategies, and reduced attention to the model when drawing the replication. © 2014 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Colour measurement of colostrum for estimation of colostral IgG and colostrum composition in dairy cows.

PubMed

Gross, Josef J; Kessler, Evelyne C; Bruckmaier, Rupert M

2014-11-01

Instruments for on-farm determination of colostrum quality such as refractometers and densimeters are increasingly used in dairy farms. The colour of colostrum is also supposed to reflect its quality. A paler or mature milk-like colour is associated with a lower colostrum value in terms of its general composition compared with a more yellowish and darker colour. The objective of this study was to investigate the relationships between colour measurement of colostrum using the CIELAB colour space (CIE L*=from white to black, a*=from red to green, b*=from yellow to blue, chroma value G=visual perceived colourfulness) and its composition. Dairy cow colostrum samples (n=117) obtained at 4·7±1·5 h after parturition were analysed for immunoglobulin G (IgG) by ELISA and for fat, protein and lactose by infrared spectroscopy. For colour measurements, a calibrated spectrophotometer was used. At a cut-off value of 50 mg IgG/ml, colour measurement had a sensitivity of 50·0%, a specificity of 49·5%, and a negative predictive value of 87·9%. Colostral IgG concentration was not correlated with the chroma value G, but with relative lightness L*. While milk fat content showed a relationship to the parameters L*, a*, b* and G from the colour measurement, milk protein content was not correlated with a*, but with L*, b*, and G. Lactose concentration in colostrum showed only a relationship with b* and G. In conclusion, parameters of the colour measurement showed clear relationships to colostral IgG, fat, protein and lactose concentration in dairy cows. Implementation of colour measuring devices in automatic milking systems and milking parlours might be a potential instrument to access colostrum quality as well as detecting abnormal milk.

Functional specialization and generalization for grouping of stimuli based on colour and motion

PubMed Central

Zeki, Semir; Stutters, Jonathan

2013-01-01

This study was undertaken to learn whether the principle of functional specialization that is evident at the level of the prestriate visual cortex extends to areas that are involved in grouping visual stimuli according to attribute, and specifically according to colour and motion. Subjects viewed, in an fMRI scanner, visual stimuli composed of moving dots, which could be either coloured or achromatic; in some stimuli the moving coloured dots were randomly distributed or moved in random directions; in others, some of the moving dots were grouped together according to colour or to direction of motion, with the number of groupings varying from 1 to 3. Increased activation was observed in area V4 in response to colour grouping and in V5 in response to motion grouping while both groupings led to activity in separate though contiguous compartments within the intraparietal cortex. The activity in all the above areas was parametrically related to the number of groupings, as was the prominent activity in Crus I of the cerebellum where the activity resulting from the two types of grouping overlapped. This suggests (a) that, the specialized visual areas of the prestriate cortex have functions beyond the processing of visual signals according to attribute, namely that of grouping signals according to colour (V4) or motion (V5); (b) that the functional separation evident in visual cortical areas devoted to motion and colour, respectively, is maintained at the level of parietal cortex, at least as far as grouping according to attribute is concerned; and (c) that, by contrast, this grouping-related functional segregation is not maintained at the level of the cerebellum. PMID:23415950

Investigation of the chemomarkers correlated with flower colour in different organs of Catharanthus roseus using NMR-based metabolomics.

PubMed

Pan, Qifang; Dai, Yuntao; Nuringtyas, Tri Rini; Mustafa, Natali Rianika; Schulte, Anna Elisabeth; Verpoorte, Robert; Choi, Young Hae

2014-01-01

Flower colour is a complex phenomenon that involves a wide range of secondary metabolites of flowers, for example phenolics and carotenoids as well as co-pigments. Biosynthesis of these metabolites, though, occurs through complicated pathways in many other plant organs. The analysis of the metabolic profile of leaves, stems and roots, for example, therefore may allow the identification of chemomarkers related to the final expression of flower colour. To investigate the metabolic profile of leaves, stems, roots and flowers of Catharanthus roseus and the possible correlation with four flower colours (orange, pink, purple and red). (1) H-NMR and multivariate data analysis were used to characterise the metabolites in the organs. The results showed that flower colour is characterised by a special pattern of metabolites such as anthocyanins, flavonoids, organic acids and sugars. The leaves, stems and roots also exhibit differences in their metabolic profiles according to the flower colour. Plants with orange flowers featured a relatively high level of kaempferol analogues in all organs except roots. Red-flowered plants showed a high level of malic acid, fumaric acid and asparagine in both flowers and leaves, and purple and pink flowering plants exhibited high levels of sucrose, glucose and 2,3-dihydroxy benzoic acid. High concentrations of quercetin analogues were detected in flowers and leaves of purple-flowered plants. There is a correlation between the metabolites specifically associated to the expression of different flower colours and the metabolite profile of other plant organs and it is therefore possible to predict the flower colours by detecting specific metabolites in leaves, stems or roots. This may have interesting application in the plant breeding industry. Copyright © 2013 John Wiley & Sons, Ltd.

Impact of Channel-like Erosion Patterns on the Frequency-Magnitude Distribution of Earthquakes

NASA Astrophysics Data System (ADS)

Rohmer, J.; Aochi, H.

2015-12-01

Reactive flow at depth (either related to underground activities like enhancement of hydrocarbon recovery, CO2 storage or to natural flow like in hydrothermal zones) can alter fractures' topography, which might in turn change their seismic responses. Depending on the flow and reaction rates, instability of the dissolution front can lead to a wormhole-like pronounced erosion pattern (Szymczak & Ladd, JGR, 2009). In a fractal structure of rupture process (Ide & Aochi, JGR, 2005), we question how the perturbation related to well-spaced long channels alters rupture propagation initiated on a weak plane and eventually the statistical feature of rupture appearance in Frequency-Magnitude Distribution FMD (Rohmer & Aochi, GJI, 2015). Contrary to intuition, a spatially uniform dissolution is not the most remarkable case, since it affects all the events proportionally to their sizes leading to a downwards translation of FMD: the slope of FMD (b-value) remains unchanged. An in-depth parametric study was carried out by considering different pattern characteristics: spacing S varying from 0 to 100 and length L from 50 to 800 and fixing the width w=1. The figure shows that there is a region of optimum channels' characteristics for which the b-value of the Gutenberg Richter law is significantly modified with p-value ~10% (corresponding to area with red-coloured boundaries) given spacing to length ratio of the order of ~1/40: large magnitude events are more significantly affected leading to an imbalanced distribution in the magnitude bins of the FMD. The larger the spacing, the lower the channel's influence. The decrease of the b-value between intact and altered fractures can reach values down to -0.08. Besides, a spatial analysis shows that the local seismicity anomaly concentrates in a limited zone around the channels: this opens perspective for detecting these eroded regions through high-resolution imaging surveys.

The colour of blood in skin: a comparison of Allen's test and photonics simulations.

PubMed

Välisuo, Petri; Kaartinen, Ilkka; Kuokkanen, Hannu; Alander, Jarmo

2010-11-01

The colour of the skin reflects many physiological and pathological states of an individual. Usually, the skin colour is examined by the bare eye alone. Several scaling systems have been developed to quantify the sensory evaluation of skin colour. In this work, the reflectance of the skin is measured directly using an objective instrument. Haemoglobin inside the dermal circulation is one of the key factors of skin colour and it also has a major role in the appearance of many skin lesions and scars. To quantitatively measure and analyse such conditions, the relation between the skin colour and the haemoglobin concentration in the skin needs to be resolved. To examine the effect of blood concentration on the skin colour, five Allen's tests were performed on 20 persons. The skin colour change was measured using a spectrophotometer by changing the blood concentration by the Allen's test. Light interaction with the skin was simulated with a Monte Carlo model, tuning the blood concentration parameter until the simulated and the measured spectra matched, yielding the relationship between the skin colour and the blood concentration. The simulation produced spectra similar to those measured. The change in the blood concentration in the simulation model and in the skin produced changes similar to the spectra. The reflectance of the skin was found to be a nonlinear function of the blood concentration. The relationship found between skin colour and blood concentration makes it possible to quantify those skin conditions expressed by blood volume better than plain colour. © 2010 John Wiley & Sons A/S.

Colour-causing defects and their related optoelectronic transitions in single crystal CVD diamond.

PubMed

Khan, R U A; Cann, B L; Martineau, P M; Samartseva, J; Freeth, J J P; Sibley, S J; Hartland, C B; Newton, M E; Dhillon, H K; Twitchen, D J

2013-07-10

Defects causing colour in nitrogen-doped chemical vapour-deposited (CVD) diamond can adversely affect the exceptional optical, electronic and spintronic properties of the material. Several techniques were used to study these defects, namely optical absorption spectroscopy, thermoluminescence (TL) and electron paramagnetic resonance (EPR). From our studies, the defects causing colour in nitrogen-doped CVD diamond are clearly not the same as those causing similar colour in natural diamonds. The brown colour arises due to a featureless absorption profile that decreases in intensity with increasing wavelength, and a broad feature at 360 nm (3.49 eV) that scales in intensity with it. Another prominent absorption band, centred at 520 nm (2.39 eV), is ascribed to the neutral nitrogen-vacancy-hydrogen defect. The defects responsible for the brown colour possess acceptor states that are 1.5 eV from the valence band (VB) edge. The brown colour is removed by heat treatment at 1600 ° C, whereupon new defects possessing shallow (<1 eV) trap states are generated.

The effect of warp tension on the colour of jacquard fabric made with different weaves structures

NASA Astrophysics Data System (ADS)

Karnoub, A.; Kadi, N.; Holmudd, O.; Peterson, J.; Skrifvars, M.

2017-10-01

The aims of this paper is to demonstrate the effect of warp tension on fabric colour for several types of weaves structures, and found a relationship between them. The image analyse technique used to determine the proportion of yarns colour appearance, the advantage of this techniques is the rapidity and reliability. The woven fabric samples are consisting of a polyester warp yarn with continuous filaments and density of 33 end/cm, a polypropylene weft yarn with a density of 24 pick/cm, and the warp tension ranged between 12-22 cN/tex. The experimental results demonstrated the effect of the warp tension on the colour of fabric, and this effect is related to several factors, where the large proportion of warp appearance leads to larger effect on fabric colour. The difference in the value of colour differences ΔEcmc is larger is in the range 16 to 20 cN/tex of warp tension. Using statistical methods, a mathematical model to calculate the amount of the colour difference ΔEcmc caused by the change in warp tension had been proposed.

[Patient-related color preference and color design in the hospital].

PubMed

Schuschke, G; Christiansen, H

1994-06-01

Colour-physiological studies involving volunteers and colour-psychological interviewing of patients with varied diagnoses revealed that, currently, no compelling scientific reasons can be given for coloration in the hospital. Interviewing 68 patients from a number of clinics on the coloration of sick-rooms yielded the following preferred colours, irrespective of the patients' classing into groups by various criteria: Light colours were consistently preferred for all objects such as ceiling, walls, floor, curtains, furniture, and bed linen. It should be emphasized that even white was a desirable colour for ceilings and bed linen. Beige was found to rank first for walls, floors, curtains, and furniture, whereas the colours of wood and grey shared the second rank for floors and furniture. Green and pink ranked second for bed linen. White and green ranked second for walls and curtains, respectively. In view of the heterogeneity, the findings may not be converted into an absolute just as the recommendations by other workers. Still, the patients' wish should be given priority over decreed recommendations by experts when basic considerations of illumination (reflectance!) are allowed for in the particular overall colour design project.

Attention, spatial integration, and the tail of response time distributions in Stroop task performance.

PubMed

Roelofs, Ardi

2012-01-01

A few studies have examined selective attention in Stroop task performance through ex-Gaussian analyses of response time (RT) distributions. It has remained unclear whether the tail of the RT distribution in vocal responding reflects spatial integration of relevant and irrelevant attributes, as suggested by Spieler, Balota, and Faust (2000). Here, two colour-word Stroop experiments with vocal responding are reported in which the spatial relation between colour and word was manipulated. Participants named colours (e.g., green; say "green") while trying to ignore distractors that were incongruent or congruent words (e.g., red or green), or neutral series of Xs. The vocal RT was measured. Colour words in colour, white words superimposed onto colour rectangles (Experiment 1), and colour rectangles combined with auditory words (Experiment 2) yielded Stroop effects in both the leading edge and the tail of the RT distributions. These results indicate that spatial integration is not necessary for effects in the tail to occur in vocal responding. It is argued that the findings are compatible with an association of the tail effects with task conflict.

Toward the development of portable miniature intelligent electronic color identification devices

NASA Astrophysics Data System (ADS)

Nicolau, Dan V., Jr.; Livingston, Peter; Jahshan, David; Evans, Rob

2004-03-01

The identification and differentiation of colours is a relatively problematic task for colour-impaired and partially vision-impaired persons and an impossible one for completely blind. In various contexts, this leads to a loss of independence or an increased risk of harm. The identification of colour using optoelectronic devices, on the other hand, can be done precisely and inexpensively. Additionally, breakthroughs in miniaturising and integrating colour sensors into biological systems may lead to significant advances in electronic implants for alleviating blindness. Here we present a functional handheld device developed for the identification of colour, intended for use by the vision-impaired. We discuss the features and limitations of the device and describe in detail one target application - the identification of different banknote denominations by the blind.

PUVA: A Monte Carlo code for intra-articular PUVA treatment of arthritis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Descalle, M.A.; Laing, T.J.; Martin, W.R.

1996-12-31

Current rheumatoid arthritis treatments are only partially successful. Intra-articular psoralen-ultraviolet light (PUVA) phototherapy appears to be a new and valid alternative. Ultraviolet laser light (UVA) delivered in the knee joint through a fiber optic is used in combination with 8-methoxypsoralen (8-MOP), a light-sensitive chemical administered orally. A few hours after ingestion, the psoralen has diffused in all body cells. Once activated by UVA light, it binds to biological molecules, inhabiting cell division and ultimately causing local control of the arthritis. The magnitude of the response is proportional to the number of photoproducts delivered to tissues (i.e., the number of absorbedmore » photons): the PUVA treatment will only be effective if a sufficient and relatively uniform dose is delivered to the diseased synovial tissues, while sparing other tissues such as cartilage. An application is being developed, based on analog Monte Carlo methods, to predict photon densities in tissues and the minimum number of intra-articular catheter positions necessary to ensure proper treatment of the diseased zone. Other interesting aspects of the problem deal with the compexity of the joint geometry, the physics of light scattering in tissues (a relatively new field of research that is not fully understood because of the variety of tissues and tissue components), and, finally, the need to include optic laws (reflection and refraction) at interfaces.« less

Multicolour CCD surface photometry for E and S0 galaxies in 10 clusters

NASA Astrophysics Data System (ADS)

Jorgensen, Inger; Franx, Marijn; Kjaergaard, Per

1995-04-01

CCD surface photometry for 232 E and S0 galaxies is presented. The galaxies are observed in Gunn r and Johnson B, or Gunn r and g. For 48 of the galaxies surface photometry in Johnson U is also presented. Aperture magnitudes in Gunn nu are derived for half of the galaxies. Galaxies in the following clusters have been observed: Abell 194, Abell 539, Abell 3381, Abell 3574, Abell S639, Abell S753, HydraI (Abell 1060), DC2345-28, Doradus and Grm15. The data are part of our ongoing study of the large-scale motions in the Universe and the physical background for the fundamental plane. We use a full model fitting technique for analysing the CCD images. This gives radial profiles of local surface brightness, colour, ellipticity and position angle. The residuals relative to the elliptical isophotes are described quantitatively by Fourier expansions. Effective radius, mean surface brightness and total magnitude are derived by fitting a de Vaucouleurs r^¼ growth curve. We have derived a characteristic radius r_n similar to the diameter D_n introduced by Dressler et al. The derivation of the effective parameters and of r_n takes the seeing into account. We confirm the results by Saglia et al. that the effects of the seeing can be substantial. Seeing-corrected values of the effective parameters and r_n are also presented for 147 E and S0 galaxies in the Coma cluster. Colours, colour gradients and geometrical parameters are derived. The photometry is internally consistent within 0.016 mag. Comparison with the photoelectric aperture photometry from Burstein et al. shows a mean offset of 0.010 mag with an rms scatter of 0.034 mag. The global photometric parameters are compared with data from Faber et al., Lucey et al. and Lucey & Carter. These comparisons imply that the typical rms errors are as follows - log r_n:+/-0.015 log r_e:+/-0.045 m_T:+/-0.09 mag; _e:+/-0.16 mag. The rms error on the combination log r_e-0.35_e which enters the fundamental plane is +/-0.020. Also, comparisons with data from Saglia et al. are presented. The accuracy of the absolute photometry, as well as the derived parameters, makes the data suitable for our investigations of the fundamental plane and of the large-scale motions in the Universe.

Ultraviolet GaN photodetectors on Si via oxide buffer heterostructures with integrated short period oxide-based distributed Bragg reflectors and leakage suppressing metal-oxide-semiconductor contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szyszka, A., E-mail: szyszka@ihp-microelectronics.com, E-mail: adam.szyszka@pwr.wroc.pl; Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wroclaw; Lupina, L.

2014-08-28

Based on a novel double step oxide buffer heterostructure approach for GaN integration on Si, we present an optimized Metal-Semiconductor-Metal (MSM)-based Ultraviolet (UV) GaN photodetector system with integrated short-period (oxide/Si) Distributed Bragg Reflector (DBR) and leakage suppressing Metal-Oxide-Semiconductor (MOS) electrode contacts. In terms of structural properties, it is demonstrated by in-situ reflection high energy electron diffraction and transmission electron microscopy-energy dispersive x-ray studies that the DBR heterostructure layers grow with high thickness homogeneity and sharp interface structures sufficient for UV applications; only minor Si diffusion into the Y{sub 2}O{sub 3} films is detected under the applied thermal growth budget. Asmore » revealed by comparative high resolution x-ray diffraction studies on GaN/oxide buffer/Si systems with and without DBR systems, the final GaN layer structure quality is not significantly influenced by the growth of the integrated DBR heterostructure. In terms of optoelectronic properties, it is demonstrated that—with respect to the basic GaN/oxide/Si system without DBR—the insertion of (a) the DBR heterostructures and (b) dark current suppressing MOS contacts enhances the photoresponsivity below the GaN band-gap related UV cut-off energy by almost up to two orders of magnitude. Given the in-situ oxide passivation capability of grown GaN surfaces and the one order of magnitude lower number of superlattice layers in case of higher refractive index contrast (oxide/Si) systems with respect to classical III-N DBR superlattices, virtual GaN substrates on Si via functional oxide buffer systems are thus a promising robust approach for future GaN-based UV detector technologies.« less

Towards universal hybrid star formation rate estimators

NASA Astrophysics Data System (ADS)

Boquien, M.; Kennicutt, R.; Calzetti, D.; Dale, D.; Galametz, M.; Sauvage, M.; Croxall, K.; Draine, B.; Kirkpatrick, A.; Kumari, N.; Hunt, L.; De Looze, I.; Pellegrini, E.; Relaño, M.; Smith, J.-D.; Tabatabaei, F.

2016-06-01

Context. To compute the star formation rate (SFR) of galaxies from the rest-frame ultraviolet (UV), it is essential to take the obscuration by dust into account. To do so, one of the most popular methods consists in combining the UV with the emission from the dust itself in the infrared (IR). Yet, different studies have derived different estimators, showing that no such hybrid estimator is truly universal. Aims: In this paper we aim at understanding and quantifying what physical processes fundamentally drive the variations between different hybrid estimators. In so doing, we aim at deriving new universal UV+IR hybrid estimators to correct the UV for dust attenuation at local and global scales, taking the intrinsic physical properties of galaxies into account. Methods: We use the CIGALE code to model the spatially resolved far-UV to far-IR spectral energy distributions of eight nearby star-forming galaxies drawn from the KINGFISH sample. This allows us to determine their local physical properties, and in particular their UV attenuation, average SFR, average specific SFR (sSFR), and their stellar mass. We then examine how hybrid estimators depend on said properties. Results: We find that hybrid UV+IR estimators strongly depend on the stellar mass surface density (in particular at 70 μm and 100 μm) and on the sSFR (in particular at 24 μm and the total infrared). Consequently, the IR scaling coefficients for UV obscuration can vary by almost an order of magnitude: from 1.55 to 13.45 at 24 μm for instance. This result contrasts with other groups who found relatively constant coefficients with small deviations. We exploit these variations to construct a new class of adaptative hybrid estimators based on observed UV to near-IR colours and near-IR luminosity densities per unit area. We find that they can reliably be extended to entire galaxies. Conclusions: The new estimators provide better estimates of attenuation-corrected UV emission than classical hybrid estimators published in the literature. Taking naturally variable impact of dust heated by old stellar populations into account, they constitute an important step towards universal estimators.

Sputum colour can identify patients with neutrophilic inflammation in asthma

PubMed Central

Gibson, Peter; Lochrin, Alyssa J; Wood, Lisa; Baines, Katherine J; Simpson, Jodie L

2017-01-01

Introduction Sputum colour is associated with neutrophilic inflammation in chronic bronchitis and chronic obstructive pulmonary disease (COPD). Neutrophilia and sputum expectoration is notable in asthma, but whether sputum colour is associated with and predicts the presence of neutrophilic inflammation in asthma is unknown. The objective of the study is to assess the ability of sputum colour in distinguishing asthma inflammatory phenotypes. Methods Induced sputum samples collected from 271 adults with stable asthma were retrospectively assessed. Sputum colour was determined using the BronkoTest sputum colour chart and correlated to differential cell counts and CXCL-8 concentration. Neutrophilic inflammation was defined as an age-corrected sputum neutrophil proportion (≥61.6% for age 20–40 years; ≥63.2% for age 40–60 and ≥67.2% for age >60 years), whereas neutrophilic bronchitis (NB) was defined as high total cell count (≥5.1×106 cells/mL) plus an increased age-corrected neutrophil proportion. The optimal cut-off for sputum colour to predict neutrophilic inflammation and NB was determined using receiver operator characteristic curve analysis. Results A sputum colour score of ≥3 represented and predicted neutrophilic inflammation with modest accuracy (area under the curve (AUC)=0.64; p<0.001, specificity=78.4%, sensitivity=49.2%). Participants with a sputum colour score of ≥3 had significantly (p<0.05) higher CXCL-8, total cells and neutrophil number and proportion. Sputum colour score was also positively correlated with these factors. Sputum colour score ≥3 predicted NB with reasonably good accuracy (AUC=0.79, p<0.001, specificity=79.3%, sensitivity=70.7%). Conclusions Visual gradation of sputum colour in asthma relates to high total cell count and neutrophilic inflammation. Assessment of sputum colour can identify adults with asthma who are likely to have NB without the need for sputum processing and differential cell count, which may facilitate asthma management. PMID:29071085

Discovery of interstellar circular polarization in the direction of the Crab Nebula.

NASA Technical Reports Server (NTRS)

Martin, P. G.; Illing, R.; Angel, J. R. P.

1972-01-01

A search in many small regions of the Crab Nebula has resulted in the detection of a small component of circular polarization. The variation of the sign and magnitude with position in the Nebula indicates that the polarization is of interstellar origin. On the basis of the polarity, strength, and colour dependence, it is concluded that the composition of the aligned grains causing this polarization is dielectric. Metallic particles are clearly ruled out. Some stars have also been observed with negative results.

Linear increases in BOLD response associated with increasing proportion of incongruent trials across time in a colour Stroop task.

PubMed

Mitchell, Rachel L C

2010-05-01

Selective attention is popularly assessed with colour Stroop tasks in which participants name the ink colour of colour words, whilst resisting interference from the natural tendency to read the words. Prior studies hinted that the key brain regions (dorsolateral prefrontal (dlPFC) and anterior cingulate cortex (ACC)) may vary their degree of involvement, dependent on attentional demand. This study aimed to determine whether a parametrically varied increase in attentional demand resulted in linearly increased activity in these regions, and/or whether additional regions would be recruited during high attentional demand. Twenty-eight healthy young adults underwent fMRI whilst naming the font colour of colour words. Linear increases in BOLD response were assessed with increasing percentage incongruent trials per block (0, 20, 40, 60, 80, and 100%). Whilst ACC activation increased linearly according to incongruity level, dlPFC activity appeared constant. Together with behavioural evidence of reduced Stroop interference, these data support a load-dependent conflict-related response in ACC, but not dlPFC.

Iridescent cellulose nanocrystal films: the link between structural colour and Bragg’s law

NASA Astrophysics Data System (ADS)

Nguyen, Thanh-Dinh; Sierra, Egoitz; Eguiraun, Harkaitz; Lizundia, Erlantz

2018-07-01

Structural colour is a phenomenon found in nature, which provides plants and animals with vibrant optical properties. The production of this colour is based on the interaction of incident light with the hierarchical organisation of submicron- and micron-sized layered structures. Cellulose nanocrystals (CNCs) are anisotropic building units formed by acid hydrolysis of native cellulose microfibers, which can disperse in aqueous media to form a photonic liquid crystal. One fascinating example of the appearance of biomimetic colour is the supramolecular assembly of CNCs into iridescent layered structures that rotate along a helical screw to yield a long-range chiral nematic order. A quick, simple and engaging experiment that allows the establishment of a direct relation between the structural colour and underlying mechanism of the light interaction with these hierarchically structured materials is reported. The obtained colour changes are explained within the theoretical framework provided by Bragg’s law and may provide an easy way to observe the macroscopic manifestation of this often abstract concept.

Optimisation of an oak chips-grape mix maceration process. Influence of chip dose and maceration time.

PubMed

Gordillo, Belén; Baca-Bocanegra, Berta; Rodriguez-Pulído, Francisco J; González-Miret, M Lourdes; García Estévez, Ignacio; Quijada-Morín, Natalia; Heredia, Francisco J; Escribano-Bailón, M Teresa

2016-09-01

Oak chips-related phenolics are able to modify the composition of red wine and modulate the colour stability. In this study, the effect of two maceration techniques, traditional and oak chips-grape mix process, on the phenolic composition and colour of Syrah red wines from warm climate was studied. Two doses of oak chips (3 and 6g/L) at two maceration times (5 and 10days) during fermentation was considered. Changes on phenolic composition (HPLC-DAD-MS), copigmentation/polymerisation (spectrophotometry), and colour (Tristimulus and Differential Colorimetry) were assessed by multivariate statistical techniques. The addition of oak chips at shorter maceration times enhanced phenolic extraction, colour and its stabilisation in comparison to the traditional maceration. On contrast, increasing chip dose in extended maceration time resulted in wines with lighter and less stable colour. Results open the possibility of optimise alternative technological applications to traditional grape maceration for avoiding the common loss of colour of wines from warm climate. Copyright © 2016 Elsevier Ltd. All rights reserved.

One trait, many signals: different information on male quality is enclosed within the same trait in a blenny fish

NASA Astrophysics Data System (ADS)

Locatello, Lisa; Pizzolon, Matteo; Rasotto, Maria Berica

2012-10-01

Colourful ornaments are traditionally evaluated as one trait. However, they could consist of several components, such as total size, colour intensity and extension, each possibly bearing its own message about one aspect of quality. Males of the blenny Salaria pavo exhibit a colourful head crest and solely care for eggs. During the breeding season, the head crest shows a yellow colouration, the intensity and relative extension of which are independent of crest size. Here, we show that: (1) carotenoids are responsible for the head crest yellow patch; (2) activating the immune system by injecting the bacterial antigen lipopolysaccharides affects both the intensity and extent of the yellow colouration; and (3) females assess males on the basis of colour patch expression. However, the response of the yellow patch to the immune challenge was dependent on head crest size. Indeed, males with a larger head crest reacted better to the simulated infection, sustaining a level of yellow patch close to pre-challenge size.

An ultraviolet investigation of the unusual eclipsing binary system FF AQR

NASA Technical Reports Server (NTRS)

Dorren, J. D.; Guinan, E. F.; Sion, E. M.

1982-01-01

A series of seven low dispersion IUE exposures in ultraviolet and wavelength regions obtained on December 6, 1981 during the eclipse of the subdwarf, during egress, and out of eclipse is analyzed. These observations and the binary phase at which they were made are shown on a schematic representation of the V-band light curve obtained in 1975. The depth in V is 0.15 mag. The circles are IUE V magnitudes from FES measures obtained during the observing run. They indicate an eclipse depth some 0.05 mag lower than expected, possibly due to difficulties with the color term in the FES calibration. The eclipse depths of Dworetsky in U, B and V were assumed in the calculations.

Phenolics content, fruit flesh colour and browning in cultivated eggplant, wild relatives and interspecific hybrids and implications for fruit quality breeding.

PubMed

Kaushik, Prashant; Gramazio, Pietro; Vilanova, Santiago; Raigón, María D; Prohens, Jaime; Plazas, Mariola

2017-12-01

Increasing the content in bioactive phenolics in the eggplant (Solanum melongena) fruit is of interest, but may result in enhanced browning. We evaluated six varieties of S. melongena, 22 accessions of wild related species and 42 interspecific hybrids between cultivated eggplant and wild relatives for phenolics content, fruit flesh colour, polyphenol oxidase (PPO) activity, and fruit flesh browning. Wild relatives generally had a higher content in phenolics and a broader range of variation than cultivated eggplant. Chlorogenic acid was the predominant (>65.0%) phenolic acid in cultivated eggplant and its primary genepool wild ancestor S. insanum, while for the other wild species on average represented <50% of the chromatogram peak area. Fruit flesh colour was lighter in S. melongena than in the wild species, while PPO activity and browning was much higher in wild species of the secondary and tertiary genepools. Interspecific hybrids between S. melongena and S. insanum were intermediate in their characteristics, while those with secondary and tertiary genepool species were more similar to the wild species. No significant correlations were found between total phenolics or chlorogenic acid contents and fruit flesh browning, but PPO activity was correlated to both the degree of browning (r=0.404) and colour difference (r=0.458). The results indicate that wild species can contribute to improving the bioactive properties of eggplant without affecting negatively fruit flesh colour and browning. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fecundity selection on ornamental plumage colour differs between ages and sexes and varies over small spatial scales.

PubMed

Parker, T H; Wilkin, T A; Barr, I R; Sheldon, B C; Rowe, L; Griffith, S C

2011-07-01

Avian plumage colours are some of the most conspicuous sexual ornaments, and yet standardized selection gradients for plumage colour have rarely been quantified. We examined patterns of fecundity selection on plumage colour in blue tits (Cyanistes caeruleus L.). When not accounting for environmental heterogeneity, we detected relatively few cases of selection. We found significant disruptive selection on adult male crown colour and yearling female chest colour and marginally nonsignificant positive linear selection on adult female crown colour. We discovered no new significant selection gradients with canonical rotation of the matrix of nonlinear selection. Next, using a long-term data set, we identified territory-level environmental variables that predicted fecundity to determine whether these variables influenced patterns of plumage selection. The first of these variables, the density of oaks within 50 m of the nest, influenced selection gradients only for yearling males. The second variable, an inverse function of nesting density, interacted with a subset of plumage selection gradients for yearling males and adult females, although the strength and direction of selection did not vary predictably with population density across these analyses. Overall, fecundity selection on plumage colour in blue tits appeared rare and inconsistent among sexes and age classes. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

Laser induced single spot oxidation of titanium

NASA Astrophysics Data System (ADS)

Jwad, Tahseen; Deng, Sunan; Butt, Haider; Dimov, S.

2016-11-01

Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels' colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

A Comparative Study of Relational Learning Capacity in Honeybees (Apis mellifera) and Stingless Bees (Melipona rufiventris)

PubMed Central

Moreno, Antonio Mauricio; de Souza, Deisy das Graças; Reinhard, Judith

2012-01-01

Background Learning of arbitrary relations is the capacity to acquire knowledge about associations between events or stimuli that do not share any similarities, and use this knowledge to make behavioural choices. This capacity is well documented in humans and vertebrates, and there is some evidence it exists in the honeybee (Apis mellifera). However, little is known about whether the ability for relational learning extends to other invertebrates, although many insects have been shown to possess excellent learning capacities in spite of their small brains. Methodology/Principal Findings Using a symbolic matching-to-sample procedure, we show that the honeybee Apis mellifera rapidly learns arbitrary relations between colours and patterns, reaching 68.2% correct choice for pattern-colour relations and 73.3% for colour-pattern relations. However, Apis mellifera does not transfer this knowledge to the symmetrical relations when the stimulus order is reversed. A second bee species, the stingless bee Melipona rufiventris from Brazil, seems unable to learn the same arbitrary relations between colours and patterns, although it exhibits excellent discrimination learning. Conclusions/Significance Our results confirm that the capacity for learning arbitrary relations is not limited to vertebrates, but even insects with small brains can perform this learning task. Interestingly, it seems to be a species-specific ability. The disparity in relational learning performance between the two bee species we tested may be linked to their specific foraging and recruitment strategies, which evolved in adaptation to different environments. PMID:23251542

A comparative study of relational learning capacity in honeybees (Apis mellifera) and stingless bees (Melipona rufiventris).

PubMed

Moreno, Antonio Mauricio; de Souza, Deisy das Graças; Reinhard, Judith

2012-01-01

Learning of arbitrary relations is the capacity to acquire knowledge about associations between events or stimuli that do not share any similarities, and use this knowledge to make behavioural choices. This capacity is well documented in humans and vertebrates, and there is some evidence it exists in the honeybee (Apis mellifera). However, little is known about whether the ability for relational learning extends to other invertebrates, although many insects have been shown to possess excellent learning capacities in spite of their small brains. Using a symbolic matching-to-sample procedure, we show that the honeybee Apis mellifera rapidly learns arbitrary relations between colours and patterns, reaching 68.2% correct choice for pattern-colour relations and 73.3% for colour-pattern relations. However, Apis mellifera does not transfer this knowledge to the symmetrical relations when the stimulus order is reversed. A second bee species, the stingless bee Melipona rufiventris from Brazil, seems unable to learn the same arbitrary relations between colours and patterns, although it exhibits excellent discrimination learning. Our results confirm that the capacity for learning arbitrary relations is not limited to vertebrates, but even insects with small brains can perform this learning task. Interestingly, it seems to be a species-specific ability. The disparity in relational learning performance between the two bee species we tested may be linked to their specific foraging and recruitment strategies, which evolved in adaptation to different environments.

Does egg colouration reflect male condition in birds?

NASA Astrophysics Data System (ADS)

Martínez-Padilla, Jesús; Dixon, Heather; Vergara, Pablo; Pérez-Rodríguez, Lorenzo; Fargallo, Juan A.

2010-05-01

How colouration provides information about individuals in birds has been a central issue in recent decades. Although much information has been derived, little is known about the adaptive significance of egg colouration in birds. A recent idea suggests that biliverdin- and porphyrin-pigmented eggs may act as a post-mating sexual signal for males to assess female quality. In birds, it is common for males to influence prelaying female condition by courtship feeding. Using Eurasian kestrels, a species that lays protoporphyrin-pigmented eggs, we descriptively assessed the influence of male feeding on egg pigmentation by considering female phenotype, condition, breeding parameters and male body condition. We found that older females and females with greyer tails (an index of individual quality) produce highly pigmented eggs. However, male body condition was the only variable that explained egg colouration when considered together with the female-related variables. Therefore, females that mated with males in better condition laid highly pigmented eggs. With the same species, we also explored the cost of producing protoporphyrin-pigmented eggs using a food-supply experiment before the laying period. Food supplementation did not increase egg pigmentation, but hatching success and egg mass were positively related to egg colouration only in food supplied pairs. We suggest that egg colouration might be costly to produce and probably suggests egg quality. However, this cost cannot be explained by female quality, but by male condition instead. In general, our results do not support the theory that egg colouration is a post-mating sexual signal in species where males determine female condition at the time of laying.

The Influence of Colour on Memory Performance: A Review

PubMed Central

Dzulkifli, Mariam Adawiah; Mustafar, Muhammad Faiz

2013-01-01

Human cognition involves many mental processes that are highly interrelated, such as perception, attention, memory, and thinking. An important and core cognitive process is memory, which is commonly associated with the storing and remembering of environmental information. An interesting issue in memory research is on ways to enhance memory performance, and thus, remembering of information. Can colour result in improved memory abilities? The present paper highlights the relationship between colours, attention, and memory performance. The significance of colour in different settings is presented first, followed by a description on the nature of human memory. The role of attention and emotional arousal on memory performance is discussed next. The review of several studies on colours and memory are meant to explain some empirical works done in the area and related issues that arise from such studies. PMID:23983571

The influence of colour on memory performance: a review.

PubMed

Dzulkifli, Mariam Adawiah; Mustafar, Muhammad Faiz

2013-03-01

Human cognition involves many mental processes that are highly interrelated, such as perception, attention, memory, and thinking. An important and core cognitive process is memory, which is commonly associated with the storing and remembering of environmental information. An interesting issue in memory research is on ways to enhance memory performance, and thus, remembering of information. Can colour result in improved memory abilities? The present paper highlights the relationship between colours, attention, and memory performance. The significance of colour in different settings is presented first, followed by a description on the nature of human memory. The role of attention and emotional arousal on memory performance is discussed next. The review of several studies on colours and memory are meant to explain some empirical works done in the area and related issues that arise from such studies.

Tooth, skin, hair and eye colour interrelationships in Greek young adults.

PubMed

Lagouvardos, Panagiotis E; Tsamali, Ioana; Papadopoulou, Christine; Polyzois, Gregory

2013-01-01

The purpose of this study was to investigate the possible interrelationships of teeth, skin, eye and hair colour. A portable colorimeter (Shade Eye NCC/Shofu) was used to record the colour in the CIELAB system of the upper right incisors in 150 dental school students, along with their skin colour at three different areas. Natural hair and eye colour was classified into several categories by a trained examiner (ICC 0.93-0.99). One-way ANOVA and correlation tests were used to statistically analyse the data. Skin was found to have significantly higher L*, b* but lower a* values than teeth (p < 0.05). A significant correlation (p < 0.05) of teeth to skin L* and a*colour coordinate was found, but not to b* coordinate (p > 0.05). Hair tones were not correlated to teeth L* or b*, but only to a*coordinate. Teeth and eye colour coordinates were not correlated (p > 0.05). Eye and hair tones were found to have the highest significant correlation (ρ = 0.369). In conclusion, teeth of this cohort were found to be lighter, less red and yellow than the skin. Teeth colour was not related to eye colour, but lighter teeth were found to be associated with lighter skins, and redder lateral incisors to lighter hair. Darker facial skins or yellower forehead areas were also associated with darker hair and vice versa. The clinical relevance of the study is that the investigated facial characteristics are inter-correlated weakly to moderately, and for this reason predicting the colour parameters of one facial characteristic by another would not be accurate, but helpful for a rough colour selection as associations show.

Rhabdom evolution in butterflies: insights from the uniquely tiered and heterogeneous ommatidia of the Glacial Apollo butterfly, Parnassius glacialis.

PubMed

Matsushita, Atsuko; Awata, Hiroko; Wakakuwa, Motohiro; Takemura, Shin-ya; Arikawa, Kentaro

2012-09-07

The eye of the Glacial Apollo butterfly, Parnassius glacialis, a 'living fossil' species of the family Papilionidae, contains three types of spectrally heterogeneous ommatidia. Electron microscopy reveals that the Apollo rhabdom is tiered. The distal tier is composed exclusively of photoreceptors expressing opsins of ultraviolet or blue-absorbing visual pigments, and the proximal tier consists of photoreceptors expressing opsins of green or red-absorbing visual pigments. This organization is unique because the distal tier of other known butterflies contains two green-sensitive photoreceptors, which probably function in improving spatial and/or motion vision. Interspecific comparison suggests that the Apollo rhabdom retains an ancestral tiered pattern with some modification to enhance its colour vision towards the long-wavelength region of the spectrum.

A Comparison between Ultraviolet Disinfection and Copper Alginate Beads within a Vortex Bioreactor for the Deactivation of Bacteria in Simulated Waste Streams with High Levels of Colour, Humic Acid and Suspended Solids

PubMed Central

Thomas, Simon F.; Rooks, Paul; Rudin, Fabian; Atkinson, Sov; Goddard, Paul; Bransgrove, Rachel M.; Mason, Paul T.; Allen, Michael J.

2014-01-01

We show in this study that the combination of a swirl flow reactor and an antimicrobial agent (in this case copper alginate beads) is a promising technique for the remediation of contaminated water in waste streams recalcitrant to UV-C treatment. This is demonstrated by comparing the viability of both common and UV-C resistant organisms in operating conditions where UV-C proves ineffective - notably high levels of solids and compounds which deflect UV-C. The swirl flow reactor is easy to construct from commonly available plumbing parts and may prove a versatile and powerful tool in waste water treatment in developing countries. PMID:25541706

Repeated evolution of camouflage in speciose desert rodents.

PubMed

Boratyński, Zbyszek; Brito, José C; Campos, João C; Cunha, José L; Granjon, Laurent; Mappes, Tapio; Ndiaye, Arame; Rzebik-Kowalska, Barbara; Serén, Nina

2017-06-14

There are two main factors explaining variation among species and the evolution of characters along phylogeny: adaptive change, including phenotypic and genetic responses to selective pressures, and phylogenetic inertia, or the resemblance between species due to shared phylogenetic history. Phenotype-habitat colour match, a classic Darwinian example of the evolution of camouflage (crypsis), offers the opportunity to test the importance of historical versus ecological mechanisms in shaping phenotypes among phylogenetically closely related taxa. To assess it, we investigated fur (phenotypic data) and habitat (remote sensing data) colourations, along with phylogenetic information, in the species-rich Gerbillus genus. Overall, we found a strong phenotype-habitat match, once the phylogenetic signal is taken into account. We found that camouflage has been acquired and lost repeatedly in the course of the evolutionary history of Gerbillus. Our results suggest that fur colouration and its covariation with habitat is a relatively labile character in mammals, potentially responding quickly to selection. Relatively unconstrained and substantial genetic basis, as well as structural and functional independence from other fitness traits of mammalian colouration might be responsible for that observation.

Differential engagement of attention and visual working memory in the representation and evaluation of the number of relevant targets and their spatial relations: Evidence from the N2pc and SPCN.

PubMed

Maheux, Manon; Jolicœur, Pierre

2017-04-01

We examined the role of attention and visual working memory in the evaluation of the number of target stimuli as well as their relative spatial position using the N2pc and the SPCN. Participants performed two tasks: a simple counting task in which they had to determine if a visual display contained one or two coloured items among grey fillers and one in which they had to identify a specific relation between two coloured items. The same stimuli were used for both tasks. Each task was designed to permit an easier evaluation of either the same-coloured or differently-coloured stimuli. We predicted a greater involvement of attention and visual working memory for more difficult stimulus-task pairings. The results confirmed these predictions and suggest that visuospatial configurations that require more time to evaluate induce a greater (and presumably longer) involvement of attention and visual working memory. Copyright © 2017 Elsevier B.V. All rights reserved.