Статті в журналах: "Dichromatic number"

1

Pleanmani, Nopparat, and Sayan Panma. "Bounds for the dichromatic number of a generalized lexicographic product of digraphs." Discrete Mathematics, Algorithms and Applications 08, no. 02 (May 26, 2016): 1650034. http://dx.doi.org/10.1142/s1793830916500348.

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A subset [Formula: see text] is acyclic if it induces an acyclic subdigraph of a digraph [Formula: see text] and the dichromatic number [Formula: see text] of [Formula: see text] is defined to be the minimum integer [Formula: see text] such that [Formula: see text] can be partitioned into [Formula: see text] acyclic subsets. In this paper, we obtain lower and upper bounds for the dichromatic number of a generalized lexicographic product and the dichromatic number of a generalized corona of digraphs in terms of dichromatic numbers of those digraphs.

2

Gishboliner, Lior, Raphael Steiner, and Tibor Szabó. "Dichromatic number and forced subdivisions." Journal of Combinatorial Theory, Series B 153 (March 2022): 1–30. http://dx.doi.org/10.1016/j.jctb.2021.10.002.

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3

Hochstättler, Winfried. "A flow theory for the dichromatic number." European Journal of Combinatorics 66 (December 2017): 160–67. http://dx.doi.org/10.1016/j.ejc.2017.06.020.

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4

Ellis, Paul, and Dániel T. Soukup. "Cycle reversions and dichromatic number in tournaments." European Journal of Combinatorics 77 (March 2019): 31–48. http://dx.doi.org/10.1016/j.ejc.2018.10.008.

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5

Joó, Attila. "Uncountable dichromatic number without short directed cycles." Journal of Graph Theory 94, no. 1 (October 21, 2019): 113–16. http://dx.doi.org/10.1002/jgt.22509.

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6

Bataineh, Khaled. "On the skein theory of dichromatic links and invariants of finite type." Journal of Knot Theory and Its Ramifications 26, no. 13 (November 2017): 1750092. http://dx.doi.org/10.1142/s0218216517500924.

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In [Dichromatic link invariants, Trans. Amer. Math. Soc. 321(1) (1990) 197–229], Hoste and Kidwell investigated the skein theory of oriented dichromatic links in [Formula: see text]. They introduced a multi-variable polynomial invariant [Formula: see text]. We use special substitutions for some of the parameters of the invariant [Formula: see text] to show how to deduce invariants of finite type from [Formula: see text] using partial derivatives. Then we consider the 2-component 1-trivial dichromatic links. We study the Vassiliev invariants of the 2-component in the complement of the 1-component, which is equivalent to studying Vassiliev invariants for knots in [Formula: see text] We give combinatorial formulas for the type-zero and type-one invariants and we connect these invariants to existing invariants such as Aicardi's invariant. This provides us with a topological meaning of the first partial derivative, which is also shown to be universal as a type-one invariant.

7

LINHARES, JOÃO M. M., PAULO D. PINTO, and SÉRGIO M. C. NASCIMENTO. "The number of discernible colors perceived by dichromats in natural scenes and the effects of colored lenses." Visual Neuroscience 25, no. 3 (May 2008): 493–99. http://dx.doi.org/10.1017/s0952523808080620.

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The number of discernible colors perceived by normal trichromats when viewing natural scenes can be estimated by analyzing idealized color volumes or hyperspectral data obtained from actual scenes. The purpose of the present work was to estimate the relative impairment in chromatic diversity experienced by dichromats when viewing natural scenes and to investigate the effects of colored lenses. The estimates were obtained computationally from the analysis of hyperspectral images of natural scenes and using a quantitative model of dichromats' vision. The color volume corresponding to each scene was represented in CIELAB color space and segmented into cubes of unitary side. For normal trichromats, the number of discernible colors was estimated by counting the number of non-empty cubes. For dichromats, an algorithm simulating for normal observers the appearance of the scenes for dichromats was used, and the number of discernible colors was then counted as for normal trichromats. The effects of colored lenses were estimated by prior filtering the spectral radiance from the scenes with the spectral transmittance function of the lenses. It was found that in dichromatic vision the number of discernible colors was about 7% of normal trichromatic vision. With some colored lenses considerable improvements in chromatic diversity were obtained for trichromats; for dichromats, however, only modest improvements could be obtained with efficiency levels dependent on the combination of scene, lens and type of deficiency.

8

Lin, Huiqiu, and Jinlong Shu. "Spectral radius of digraphs with given dichromatic number." Linear Algebra and its Applications 434, no. 12 (June 2011): 2462–67. http://dx.doi.org/10.1016/j.laa.2010.12.026.

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9

Hochstättler, Winfried. "Towards a flow theory for the dichromatic number." Electronic Notes in Discrete Mathematics 49 (November 2015): 101–6. http://dx.doi.org/10.1016/j.endm.2015.06.016.

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STOŠIĆ, MARKO. "CATEGORIFICATION OF THE DICHROMATIC POLYNOMIAL FOR GRAPHS." Journal of Knot Theory and Its Ramifications 17, no. 01 (January 2008): 31–45. http://dx.doi.org/10.1142/s0218216508005975.

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For each graph and each positive integer n, we define a chain complex whose graded Euler characteristic is equal to an appropriate n-specialization of the dichromatic polynomial. This also gives a categorification of n-specializations of the Tutte polynomial of graphs. Also, for each graph and integer n ≤ 2, we define the different one-variable n-specializations of the dichromatic polynomial, and for each polynomial, we define graded chain complex whose graded Euler characteristic is equal to that polynomial. Furthermore, we explicitly categorify the specialization of the Tutte polynomial for graphs which corresponds to the Jones polynomial of the appropriate alternating link.

11

Neumann-Lara, Victor. "Dichromatic number, circulant tournaments and Zykov sums of digraphs." Discussiones Mathematicae Graph Theory 20, no. 2 (2000): 197. http://dx.doi.org/10.7151/dmgt.1119.

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12

Javier, Nahid, and Bernardo Llano. "The dichromatic number of infinite families of circulant tournaments." Discussiones Mathematicae Graph Theory 37, no. 1 (2017): 221. http://dx.doi.org/10.7151/dmgt.1930.

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13

Ellis, Paul, Attila Joó, and Dániel T. Soukup. "Reducing the dichromatic number via cycle reversions in infinite digraphs." European Journal of Combinatorics 90 (December 2020): 103196. http://dx.doi.org/10.1016/j.ejc.2020.103196.

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14

Kim, Yongsu, Sangryong Bae, and Changku Kang. "Quantitative analysis of carapace pattern polymorphism in the grapsid crab Hemigrapsus penicillatus (De Haan, 1835) (Decapoda, Varunidae)." Crustaceana 93, no. 1 (February 6, 2020): 77–87. http://dx.doi.org/10.1163/15685403-00003960.

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Abstract Many shore crabs exhibit juvenile colour pattern polymorphism on their carapace, which helps avoid predation through camouflage. However, colour pattern polymorphism has been described only in a limited number of species, and its quantitative descriptions are rare. Here, we studied the Asian grapsid crab Hemigrapsus penicillatus to describe its polymorphic dichromatic carapace patterns. We specifically examined how dichromatic patterns and the degree of pattern polymorphism change as size increases and whether sexual/size differences exist in carapace patterns. Our results showed that H. penicillatus exhibits polymorphic forms in both the juvenile and adult stages. Additionally, compared with males, females were more likely to exhibit dichromatic carapace patterns and had a larger light-coloured area on their carapace. Estimation of the likelihood of the carapace being light or dark coloured suggested that certain areas on the carapace are less variable than other areas. We discuss potential adaptive explanations for our results.

15

Stošić, Marko. "New categorifications of the chromatic and dichromatic polynomials for graphs." Fundamenta Mathematicae 190 (2006): 231–43. http://dx.doi.org/10.4064/fm190-0-9.

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16

GONZÁLEZ-MORENO, D., B. LLANO, and E. RIVERA-CAMPO. "A Note on the Feedback Arc Set Problem and Acyclic Subdigraphs in Bipartite Tournaments." Journal of Interconnection Networks 17, no. 03n04 (September 2017): 1741004. http://dx.doi.org/10.1142/s0219265917410043.

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Given a digraph D a feedback arc set is a subset X of the arcs of D such that D − X is acyclic. Let β(D) denote de minimum cardinality of a feedback arc set of D. In this paper we prove that a bipartite tournament T with minimum out-degree at least r satisfies β(T) ≥ r2. A lower bound and an upper bound for β(T) are given in terms of the bipartite dichromatic number. We define the bipartite dichromatic number of a balanced bipartite tournament Tn,n and use this invariant to give an upper bound for the minimum cardinality of a feedback arc set of Tn,n. We also prove that for each positive integer k ≥ 3 there is an integer N(k) such that if n ≥ N(k), then each balanced bipartite tournament contains an acyclic bipartite tournament Tk,k.

17

NAKABO, SHIGEKAZU. "LINKS IN A SOLID TORUS AND DICHROMATIC LINK INVARIANTS DERIVED FROM QUANTUM GROUPS." Journal of Knot Theory and Its Ramifications 03, no. 02 (June 1994): 187–95. http://dx.doi.org/10.1142/s0218216594000149.

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We give an algorithm to simplify the calculation of the inavriants of links in a solid torus, which are defined by means of the representations of [Formula: see text] and the height function. The explicit formula of the initial data for this procedure is presented. Lastely, we observe that the invariant in the simplest level gives an example belonging to a class of 1-trivial dichromatic link invariants different from that defined by Hoste and Kidwell.

18

Yang, Xiuwen, Hajo Broersma, and Ligong Wang. "Sharp bounds for Laplacian spectral moments of digraphs with a fixed dichromatic number." Discrete Mathematics 347, no. 1 (January 2024): 113659. http://dx.doi.org/10.1016/j.disc.2023.113659.

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19

Masello, Juan F., Thomas Lubjuhn, and Petra Quillfeldt. "Hidden dichromatism in the Burrowing Parrot (Cyanoliseus patagonus) as revealed by spectrometric colour analysis." El Hornero 24, no. 1 (August 1, 2009): 47–55. http://dx.doi.org/10.56178/eh.v24i1.729.

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Bird colour perception differs fundamentally from that of humans. Birds have more cone types in the retina, including UV or violet cones, which enable them to perceive a wider spectral range. Thus, human colour perception can be deceiving when assessing functional aspects of bird plumage coloration, such as the intensity of sexual selection. In this study we measured reflectance spectra of different plumage regions of male and female Burrowing Parrot (Cyanoliseus patagonus) individuals. Although not obvious to human eyes, spectrometry revealed that adults are sexually dichromatic. Plumage regions with structure-based (blue) and structure-psittacofulvin pigment-based (green) coloration differed in achromatic brightness. In contrast, the psittacofulvin-based (red) region differed in spectral shape between the sexes. Thus, Burrowing Parrot is among the growing number of bird species which were formerly classed as sexually monochromatic based on human vision, but which are actually sexually dichromatic.

20

JIN, XIAN'AN, and FUJI ZHANG. "ORIENTED STATE MODEL OF THE JONES POLYNOMIAL AND ITS CONNECTION TO THE DICHROMATIC POLYNOMIAL." Journal of Knot Theory and Its Ramifications 19, no. 01 (January 2010): 81–92. http://dx.doi.org/10.1142/s0218216510007759.

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It is well known that Kauffman constructed a state model of the Jones polynomial based on unoriented link diagrams. In his approach, in order to obtain Jones polynomial one needs to calculate both the writhe and the Kauffman bracket. Stimulated by a paper of Altintas (An oriented state model for the Jones polynomial and its applications to alternating links, Appl. Math. Comput.194 (2007) 168–178), in this paper we present a state sum model based on oriented link diagrams. In our approach, we succeed in adding the writhe to the state sum model and need not to compute the writher any more. We further show that, via our state sum model, Jones polynomial of any link (alternating or not) is a special parametrization of the dichromatic polynomial of a weighted graph with two different edge weights.

21

ROWE, MICKEY P., and GERALD H. JACOBS. "Cone pigment polymorphism in New World monkeys: Are all pigments created equal?" Visual Neuroscience 21, no. 3 (May 2004): 217–22. http://dx.doi.org/10.1017/s0952523804213104.

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Most platyrrhine monkeys have a triallelic M/L opsin gene polymorphism that underlies significant individual variations in color vision. A survey of the frequencies of these polymorphic genes suggests that the three alleles occur with equal frequency among squirrel monkeys (subfamily Cebinae), but are not equally frequent in a number of species from the subfamily Callitrichinae. This departure from equal frequency in the Callitrichids should slightly increase the ratio of dichromats to trichromats in the population and significantly alter the relative representation of the three possible dichromatic and trichromatic phenotypes. A particular feature of the inequality is that it leads to a relative increase in the number of trichromats whose M/L pigments have the largest possible spectral separation. To assess whether these trichromatic phenotypes are equally well equipped to make relevant visual discriminations, psychophysical experiments were run on human observers. A technique involving the functional substitution of photopigments was used to simulate the discrimination between fruits among a background of leaves. The goal of the simulation was to reproduce in the cones of human observers excitations equivalent to those produced in monkey cones as the animals view fruit. Three different viewing conditions were examined involving variations in the relative luminances of fruit and leaves and the spectrum of the illuminant. In all cases, performance was best for simulated trichromacies including M/L pigments with the largest spectral separation. Thus, the inequality of opsin gene frequency in Callitrichid monkeys may reflect adaptive pressures.

22

BONNARDEL, VALÉRIE. "Color naming and categorization in inherited color vision deficiencies." Visual Neuroscience 23, no. 3-4 (May 2006): 637–43. http://dx.doi.org/10.1017/s0952523806233558.

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Dichromatic subjects can name colors accurately, even though they cannot discriminate among red-green hues (Jameson & Hurvich, 1978). This result is attributed to a normative language system that dichromatic observers developed by learning subtle visual cues to compensate for their impoverished color system. The present study used multidimensional scaling techniques to compare color categorization spaces of color-vision deficient (CVD) subjects to those of normal trichromat (NT) subjects, and consensus analysis estimated the normative effect of language on categorization. Subjects sorted 140 Munsell color samples in three different ways: a free sorting task (unlimited number of categories), a constrained sorting task (number of categories limited to eight), and a constrained naming task (limited to eight basic color terms). CVD color categories were comparable to those of NT subjects. For both CVD and NT subjects, a common color categorization space derived from the three tasks was well described by a three-dimensional model, with the first two dimensions corresponding to reddish-greenish and yellowish-bluish axes. However, the third axis, which was associated with an achromatic dimension in NTs, was not identified in the CVD model. Individual differences multidimensional scaling failed to reveal group differences in the sorting tasks. In contrast, the personal color naming spaces of CVD subjects exhibited a relative compression of the yellowish-bluish dimension that is inconsistent with the typical deutan-type color spaces derived from more direct measures of perceptual color judgments. As expected, the highest consensus among CVDs (77%) and NTs (82%) occurred in the naming task. The categorization behaviors studied in this experiment seemed to rely more on learning factors, and may reveal little about CVD perceptual representation of colors.

23

Fennell, J. G., L. Talas, R. J. Baddeley, I. C. Cuthill, and N. E. Scott-Samuel. "Optimizing colour for camouflage and visibility using deep learning: the effects of the environment and the observer's visual system." Journal of The Royal Society Interface 16, no. 154 (May 2019): 20190183. http://dx.doi.org/10.1098/rsif.2019.0183.

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Avoiding detection can provide significant survival advantages for prey, predators, or the military; conversely, maximizing visibility would be useful for signalling. One simple determinant of detectability is an animal's colour relative to its environment. But identifying the optimal colour to minimize (or maximize) detectability in a given natural environment is complex, partly because of the nature of the perceptual space. Here for the first time, using image processing techniques to embed targets into realistic environments together with psychophysics to estimate detectability and deep neural networks to interpolate between sampled colours, we propose a method to identify the optimal colour that either minimizes or maximizes visibility. We apply our approach in two natural environments (temperate forest and semi-arid desert) and show how a comparatively small number of samples can be used to predict robustly the most and least effective colours for camouflage. To illustrate how our approach can be generalized to other non-human visual systems, we also identify the optimum colours for concealment and visibility when viewed by simulated red–green colour-blind dichromats, typical for non-human mammals. Contrasting the results from these visual systems sheds light on why some predators seem, at least to humans, to have colouring that would appear detrimental to ambush hunting. We found that for simulated dichromatic observers, colour strongly affected detection time for both environments. In contrast, trichromatic observers were more effective at breaking camouflage.

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Neitz, Jay, and Gerald H. Jacobs. "Spectral sensitivity of cones in an ungulate." Visual Neuroscience 2, no. 2 (February 1989): 97–100. http://dx.doi.org/10.1017/s0952523800011949.

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AbstractUngulates have been classified as having arrhythmic eyes in the sense that they contain features appropriate both to diurnal and nocturnal life. The former is typically associated with multiple classes of cones and a color-vision capacity. To see if an arrhythmic animal has these features, the number of cone classes was determined and the spectra of these cones were measured in a common ungulate, the domestic pig (Sus scrofa). Examination with electroretinogram (ERG) flicker photometry revealed the presence of two classes of cones in the pig's eye having average maximum sensitivity (λmax) at 439 nm and 556 nm, respectively. This ungulate thus has the requisite retinal basis for dichromatic color vision.

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CONWAY, KEVIN W., and MAURICE KOTTELAT. "Boraras naevus, a new species of miniature and sexually dichromatic freshwater fish from peninsular Thailand (Ostariophysi: Cyprinidae)." Zootaxa 3002, no. 1 (August 24, 2011): 45. http://dx.doi.org/10.11646/zootaxa.3002.1.4.

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Boraras naevus, new species, is described from peninsular Thailand. It is distinguished from other congeners by features of its sexually dimorphic colour pattern, principal caudal-fin, pelvic-fin and branched dorsal-fin ray counts, lateral scale row counts, and a number of osteological features.

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Zienko, S. I., and V. L. Zhbanova. "Frequency and time domain characteristics of the insect visual system in optic flow." Биофизика 68, no. 1 (February 15, 2023): 98–107. http://dx.doi.org/10.31857/s0006302923010106.

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Frequency and time domain properties of the monochromatic, dichromatic, and trichromatic visual system in an insect have been studied. The research method is based on the representation of the optical flow field of the insect visual system in the form of a dynamic link with an input and output. The Gaussian function was used to approximate the spectral curves. The study of the inertial properties of such a link in the time domain was performed by applying signals to its input in the form of a δ-function or a unit function. The steady-state forced oscillations at the output of the investigated dynamic link are determined when a harmonic effect is applied to the input. A technique for constructing spectral sensitivity curves for monochrome, dichromatic, and trichromatic vision of insects in the frequency domain is proposed; it has been established that the spectra exhibit the properties of ultra wideband signals. It has been found that the dynamic link of the insect visual system is capable of amplifying the optical signal over ultraviolet and blue parts of the spectrum in the time and frequency domain. It has been revealed that at a frequency equal to or higher than the frequency of dielectric relaxation, the optical flow field of the insect's visual system does not sense electromagnetic radiation. This phenomenon is most pronounced in ultraviolet and blue parts of the spectrum. It has been established that the optical signal wideband index μ varies from 0.41 to 1.21; thus, the visual system of an insect has ultra wideband properties. It has been shown that the number of periods of light oscillations in the visual system of insects, which has a spectrum in the form of a Gaussian curve, is related to the exponent μ by a simple relationship. New knowledge gained can be used for creation of matrix solid-state photodetectors in ultraviolet and blue parts of the spectrum.

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C.A. Hall, H. J. Cassaday, C. J. Vincent, and A. M. Derrington. "The selection of coloured stimuli by the horse (Equus caballus)." BSAP Occasional Publication 35 (2006): 217–21. http://dx.doi.org/10.1017/s0263967x00042750.

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Colour is an important feature that increases the visibility of objects and may aid recognition of con-specifics. The adaptive significance of the ability to utilize colour cues has been demonstrated in a number of species, in particular in relation to food selection. The evolution of trichromatic colour vision in primates has been associated with the advantages that it provided in the selection of yellow and orange fruits (Mollon, 1989) or tender young red foliage (Dominy and Lucas, 2001) from a background of green. The horse is a generalist herbivore that must both select nutritious plants and avoid toxic ones. Familiarity is an important factor in this selection process (Augner et al., 1998), although it is not clear exactly what features are used to recognise previously ingested and “safe” herbage.The horse has been shown to possess dichromatic colour vision. There are two types of cone photopigment in the equine retina, with spectral peaks at 429 and 545 nanometres (Macuda, 2000).

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FASICK, JEFFRY I., THOMAS W. CRONIN, DAVID M. HUNT, and PHYLLIS R. ROBINSON. "The visual pigments of the bottlenose dolphin (Tursiops truncatus)." Visual Neuroscience 15, no. 4 (April 1998): 643–51. http://dx.doi.org/10.1017/s0952523898154056.

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To assess the dolphin's capacity for color vision and determine the absorption maxima of the dolphin visual pigments, we have cloned and expressed the dolphin opsin genes. On the basis of sequence homology with other mammalian opsins, a dolphin rod and long-wavelength sensitive (LWS) cone opsin cDNAs were identified. Both dolphin opsin cDNAs were expressed in mammalian COS-7 cells. The resulting proteins were reconstituted with the chromophore 11-cis-retinal resulting in functional pigments with absorption maxima (λmax) of 488 and 524 nm for the rod and cone pigments respectively. These λmax values are considerably blue shifted compared to those of many terrestrial mammals. Although the dolphin possesses a gene homologous to other mammalian short-wavelength sensitive (SWS) opsins, it is not expressed in vivo and has accumulated a number of deletions, including a frame-shift mutation at nucleotide position 31. The dolphin therefore lacks the common dichromatic form of color vision typical of most terrestrial mammals.

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D. Salmon, E., J. C. Waters, and C. Waterman-Storer. "Multi-mode light microscopy of microtubule assembly dynamics and chromosome movement in vivo and In vitro." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 730–31. http://dx.doi.org/10.1017/s0424820100166117.

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We have developed a multi-mode digital imaging system which acquires images with a cooled CCD camera (Figure 1). A multiple band pass dichromatic mirror and robotically controlled filter wheels provide wavelength selection for epi-fluorescence. Shutters select illumination either by epi-fluorescence or by transmitted light for phase contrast or DIC. Many of our experiments involve investigations of spindle assembly dynamics and chromosome movements in live cells or unfixed reconstituted preparations in vitro in which photodamage and phototoxicity are major concerns. As a consequence, a major factor in the design was optical efficiency: achieving the highest image quality with the least number of illumination photons. This principle applies to both epi-fluorescence and transmitted light imaging modes. In living cells and extracts, microtubules are visualized using X-rhodamine labeled tubulin. Photoactivation of C2CF-fluorescein labeled tubulin is used to locally mark microtubules in studies of microtubule dynamics and translocation. Chromosomes are labeled with DAPI or Hoechst DNA intercalating dyes.

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Ogawa, Yuri, Marcin Falkowski, Ajay Narendra, Jochen Zeil, and Jan M. Hemmi. "Three spectrally distinct photoreceptors in diurnal and nocturnal Australian ants." Proceedings of the Royal Society B: Biological Sciences 282, no. 1808 (June 7, 2015): 20150673. http://dx.doi.org/10.1098/rspb.2015.0673.

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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 ( λ max ) 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 ( λ max ) 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.

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SCOLARO, JOSÉ ALEJANDRO, and DANIEL PINCHEIRA-DONOSO. "Lizards at the end of the world: Two new species of Phymaturus of the patagonicus clade (Squamata, Liolaemidae) revealed in southern Patagonia of Argentina." Zootaxa 2393, no. 1 (March 9, 2010): 17. http://dx.doi.org/10.11646/zootaxa.2393.1.2.

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The Liolaemidae radiation has resulted in three genera whose patterns of evolutionary diversification exhibit dramatic differences. Two of these lineages, Ctenoblepharys and Liolaemus, lay at the extremes, being a monotypic genus and one of the most extraordinary adaptive radiations among vertebrates, respectively. In Phymaturus, in contrast, 22 species are known, all characterized by similar ecological niches and life-history patterns. The Phymaturus genus consists of two major clades, flagellifer and patagonicus, restricted to Andean-Patagonian environments in Argentina and Chile. While the former lineage occurs primarily at the northern areas of the genus distribution, the latter mostly occupies central and southern Patagonia. In this study, we report evidence to support the existence of two new species of the genus belonging to the austral clade patagonicus. These new taxa, Phymaturus castillensis and Phymaturus videlai, occur close to the southernmost distributional limit known for the entire genus. At these austral latitudes, only two other species of the genus, P. indistinctus and P. patagonicus, have been found. Therefore, the two new species reported herein reveal a higher species richness at these cold and harsh South American environments, where the predominant lineage is Liolaemus. As in the rest of the species of the Phymaturus genus, P. castillensis and P. videlai are saxicolous, herbivorous, and viviparous, as revealed by our field and lab observations. A number of signals support the idea that these two Phymaturus populations are the result of speciation events. Essentially, both are strongly isolated by hundreds of kilometers from most species of the patagonicus clade, which precludes dynamic gene exchange among them, while substantial divergence in their patterns of coloration differentiate them from the two geographically closest species, P. indistinctus and P. patagonicus, and from each other. The differences in coloration are not, however, strongly accentuated between the sexes, being monochromatic in P. castillensis and moderately dichromatic in P. videlai. Interestingly, juveniles P. videlai exhibit also these signals of adult sexual dichromatism. Finally, the results reported in this study increase Phymaturus species richness up to 24 species.

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Pietersen, A. N. J., S. K. Cheong, S. G. Solomon, C. Tailby, and P. R. Martin. "Temporal response properties of koniocellular (blue-on and blue-off) cells in marmoset lateral geniculate nucleus." Journal of Neurophysiology 112, no. 6 (September 15, 2014): 1421–38. http://dx.doi.org/10.1152/jn.00077.2014.

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Visual perception requires integrating signals arriving at different times from parallel visual streams. For example, signals carried on the phasic-magnocellular (MC) pathway reach the cerebral cortex pathways some tens of milliseconds before signals traveling on the tonic-parvocellular (PC) pathway. Visual latencies of cells in the koniocellular (KC) pathway have not been specifically studied in simian primates. Here we compared MC and PC cells to “blue-on” (BON) and “blue-off” (BOF) KC cells; these cells carry visual signals originating in short-wavelength-sensitive (S) cones. We made extracellular recordings in the lateral geniculate nucleus (LGN) of anesthetized marmosets. We found that BON visual latencies are 10–20 ms longer than those of PC or MC cells. A small number of recorded BOF cells ( n = 7) had latencies 10–20 ms longer than those of BON cells. Within all cell groups, latencies of foveal receptive fields (<10° eccentricity) were longer (by 3–8 ms) than latencies of peripheral receptive fields (>10°). Latencies of yellow-off inputs to BON cells lagged the blue-on inputs by up to 30 ms, but no differences in visual latency were seen on comparing marmosets expressing dichromatic (“red-green color-blind”) or trichromatic color vision phenotype. We conclude that S-cone signals leaving the LGN on KC pathways are delayed with respect to signals traveling on PC and MC pathways. Cortical circuits serving color vision must therefore integrate across delays in (red-green) chromatic signals carried by PC cells and (blue-yellow) signals carried by KC cells.

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Corso, Josmael, Mark Bowler, Eckhard W. Heymann, Christian Roos, and Nicholas I. Mundy. "Highly polymorphic colour vision in a New World monkey with red facial skin, the bald uakari ( Cacajao calvus )." Proceedings of the Royal Society B: Biological Sciences 283, no. 1828 (April 13, 2016): 20160067. http://dx.doi.org/10.1098/rspb.2016.0067.

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Colour vision is highly variable in New World monkeys (NWMs). Evidence for the adaptive basis of colour vision in this group has largely centred on environmental features such as foraging benefits for differently coloured foods or predator detection, whereas selection on colour vision for sociosexual communication is an alternative hypothesis that has received little attention. The colour vision of uakaris ( Cacajao ) is of particular interest because these monkeys have the most dramatic red facial skin of any primate, as well as a unique fission/fusion social system and a specialist diet of seeds. Here, we investigate colour vision in a wild population of the bald uakari, C. calvus , by genotyping the X-linked opsin locus. We document the presence of a polymorphic colour vision system with an unprecedented number of functional alleles (six), including a novel allele with a predicted maximum spectral sensitivity of 555 nm. This supports the presence of strong balancing selection on different alleles at this locus. We consider different hypotheses to explain this selection. One possibility is that trichromacy functions in sexual selection, enabling females to choose high-quality males on the basis of red facial coloration. In support of this, there is some evidence that health affects facial coloration in uakaris, as well as a high prevalence of blood-borne parasitism in wild uakari populations. Alternatively, the low proportion of heterozygous female trichromats in the population may indicate selection on different dichromatic phenotypes, which might be related to cryptic food coloration. We have uncovered unexpected diversity in the last major lineage of NWMs to be assayed for colour vision, which will provide an interesting system to dissect adaptation of polymorphic trichromacy.

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Ahnelt, Peter K., Jan Nora Hokoç, and Pal Röhlich. "Photoreceptors in a primitive mammal, the South American opossum, Didelphis marsupialis aurita: Characterization with anti-opsin immunolabeling." Visual Neuroscience 12, no. 5 (September 1995): 793–804. http://dx.doi.org/10.1017/s0952523800009366.

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AbstractThe retinas of placental mammals appear to lack the large number and morphological diversity of cone subtypes found in diurnal reptiles. We have now studied the photoreceptor layer of a South American marsupial (Didelphis marsupialis aurita) by peanut agglutinin labeling of the cone sheath and by labeling of cone outer segments with monoclonal anti-visual pigment antibodies that have been proven to consistently label middle-to-long wavelength (COS-1) and short-wavelength (OS-2) cone subpopulations in placental mammals. Besides a dominant rod population (max. = 400,000/mm2) four subtypes of cones (max. = 3000/mm2) were identified. The outer segments of three cone subtypes were labeled by COS-1: a double cone with a principal cone containing a colorless oil droplet, a single cone with oil droplet, and another single cone. A second group of single cones lacking oil droplets was labeled by OS-2 antibody. The topography of these cone subtypes showed striking anisotropies. The COS-1 labeled single cones without oil droplets were found all over the retina and constituted the dominant population in the area centralis located in the temporal quadrant of the upper, tapetal hemisphere. The population of OS-2 labeled cones was also ubiquitous although slightly higher in the upper hemisphere (200/mm2). The COS-1 labeled cones bearing an oil droplet, including the principal member of double cones, were concentrated (800/mm2) in the inferior, non-tapetal half of the retina. The two spectral types of single cones resemble those of dichromatic photopic systems in most placental mammals. The additional set of COS-1 labeled cones is a distinct marsupial feature. The presence of oil droplets in this cone subpopulation, its absence in the area centralis, and the correlation with the non-tapetal inferior hemisphere suggest a functional specialization, possibly for mesopic conditions. Thus, sauropsid features have been retained but probably with a modified function.

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Lee, Su Hyeon, Hyo Jun Won, Seunghyun Ban, Hyelim Choi, and Je Hyeong Jung. "Tomato Fruit Growth and Nutrient Accumulation in Response to Blue and Red Light Treatments during the Reproductive Growth Stage." Horticulturae 9, no. 10 (October 9, 2023): 1113. http://dx.doi.org/10.3390/horticulturae9101113.

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Tomatoes are an important fruit consumed worldwide. Within protected cultivation environments, artificial light using energy-efficient light-emitting diodes can be applied in tomato production as an effective way to improve productivity and nutritional value. Several studies have investigated the effects of supplementing artificial light on various aspects of tomato growth, encompassing flowering, fruit development, ripening, and nutritional composition. However, the outcomes of previous studies offer inconclusive insights into whether the observed impacts on tomato growth have resulted from the provision of additional photons or discrepancies in the spectral distribution of light during artificial light supplementation. Within this context, this study aimed to specifically explore the independent effects of monochromatic blue and red light, along with their dichromatic mixture (blue + red), on fruit growth and nutrient accumulation in comparison with multispectral white light. These four different light treatments were implemented after anthesis under the same photosynthetic photon flux density to mitigate possible variabilities arising from different light intensities and originating during the vegetative growth stage. As a result, under the same light intensity conditions, red and blue + red light irradiance during the reproductive growth stage delayed fruit ripening by up to 4.33 days compared to white light. Regarding fruit productivity, the fresh weight of fully ripe tomato fruit in the blue, red, or blue + red light treatment groups was not different from that in the white-light treatment group, whereas the blue light treatment significantly reduced the number of fruits in the plant. Finally, nutrient content, including soluble sugars, lycopene, and β-carotene, significantly increased by 10.0%, 27.1%, and 65.2%, respectively, in the blue compared to the white light-irradiated group. This study demonstrated that the application of distinct light spectra during the reproductive growth phase could have varying impacts on tomato fruit development and nutrient accumulation. By integrating our findings with results from prior studies, a more efficient light intervention strategy could be developed to effectively regulate traits of tomato fruit within an indoor production system.

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Meng, Qingwu, and Erik S. Runkle. "Blue Photons from Broad-Spectrum LEDs Control Growth, Morphology, and Coloration of Indoor Hydroponic Red-Leaf Lettuce." Plants 12, no. 5 (March 2, 2023): 1127. http://dx.doi.org/10.3390/plants12051127.

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For indoor crop production, blue + red light-emitting diodes (LEDs) have high photosynthetic efficacy but create pink or purple hues unsuitable for workers to inspect crops. Adding green light to blue + red light forms a broad spectrum (white light), which is created by: phosphor-converted blue LEDs that cast photons with longer wavelengths, or a combination of blue, green, and red LEDs. A broad spectrum typically has a lower energy efficiency than dichromatic blue + red light but increases color rendering and creates a visually pleasing work environment. Lettuce growth depends on the interactions of blue and green light, but it is not clear how phosphor-converted broad spectra, with or without supplemental blue and red light, influence crop growth and quality. We grew red-leaf lettuce ‘Rouxai’ in an indoor deep-flow hydroponic system at 22 °C air temperature and ambient CO2. Upon germination, plants received six LED treatments delivering different blue fractions (from 7% to 35%) but the same total photon flux density (400 to 799 nm) of 180 μmol·m−2·s−1 under a 20 h photoperiod. The six LED treatments were: (1) warm white (WW180); (2) mint white (MW180); (3) MW100 + blue10 + red70; (4) blue20 + green60 + red100; (5) MW100 + blue50 + red30; and (6) blue60 + green60 + red60. Subscripts denote photon flux densities in μmol·m−2·s−1. Treatments 3 and 4 had similar blue, green, and red photon flux densities, as did treatments 5 and 6. At the harvest of mature plants, lettuce biomass, morphology, and color were similar under WW180 and MW180, which had different green and red fractions but similar blue fractions. As the blue fraction in broad spectra increased, shoot fresh mass, shoot dry mass, leaf number, leaf size, and plant diameter generally decreased and red leaf coloration intensified. Compared to blue + green + red LEDs, white LEDs supplemented with blue + red LEDs had similar effects on lettuce when they delivered similar blue, green, and red photon flux densities. We conclude that the blue photon flux density in broad spectra predominantly controls lettuce biomass, morphology, and coloration.

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Wilder, Heath D., Ulrike Grünert, Barry B. Lee, and Paul R. Martin. "Topography of ganglion cells and photoreceptors in the retina of a New World monkey: The marmoset Callithrix jacchus." Visual Neuroscience 13, no. 2 (March 1996): 335–52. http://dx.doi.org/10.1017/s0952523800007586.

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AbstractWe studied the anatomical substrates of spatial vision in a New World monkey, the marmoset Callithrix jacchus. This species has good visual acuity and a foveal specialization which is qualitatively similar to that of humans and other Old World primates.We measured the spatial density of retinal ganglion cells and photoreceptors, and calculated the relative numbers of these cell populations. We find that ganglion cells outnumber photoreceptors by between 2.4:1 and 4.2:1 in the fovea. The peak sampling density of ganglion cells is close to 550,000 cells/mm2. This value falls by almost 1000-fold between the fovea and peripheral retina; a value which approaches recent estimates of the centroperipheral ganglion cell gradient for human and macaque monkey retina and primary visual cortex. The marmoset shows a sex-linked polymorphism of color vision: all male and some female marmosets are dichromats. Six of the retinas used in the present study came from animals whose chromatic phenotype was identified in electrophysiological experiments and confirmed by polymerase chain reaction (PCR) amplification of cone opsin encoding genes. One animal was a trichromat and the others were dichromats. Antibodies against short wavelength-sensitive (SWS) cones labeled close to 8% of all cones near the fovea of onedichromat animal, consistent with electrophysiological evidence that the SWS system is present inall marmosets. The topography and spatial density of cone photoreceptors and ganglion cells was similar to that reported for macaque retina, and we found no obvious difference between dichromatic and trichromatic marmoset retinas. These results reinforce the view that the main determinate of primate foveal topography is the requirement for maximal spatial resolution.

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Joó, Attila. "On the growth rate of dichromatic numbers of finite subdigraphs." Discrete Mathematics 343, no. 3 (March 2020): 111735. http://dx.doi.org/10.1016/j.disc.2019.111735.

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da Fonseca, María, and Inés Samengo. "Novel Perceptually Uniform Chromatic Space." Neural Computation 30, no. 6 (June 2018): 1612–23. http://dx.doi.org/10.1162/neco_a_01073.

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Chromatically perceptive observers are endowed with a sense of similarity between colors. For example, two shades of green that are only slightly discriminable are perceived as similar, whereas other pairs of colors, for example, blue and yellow, typically elicit markedly different sensations. The notion of similarity need not be shared by different observers. Dichromat and trichromat subjects perceive colors differently, and two dichromats (or two trichromats, for that matter) may judge chromatic differences inconsistently. Moreover, there is ample evidence that different animal species sense colors diversely. To capture the subjective metric of color perception, here we construct a notion of distance in color space based on the physiology of the retina, and is thereby individually tailored for different observers. By applying the Fisher metric to an analytical model of color representation, we construct a notion of distance that reproduces behavioral experiments of classical discrimination tasks. We then derive a coordinate transformation that defines a new chromatic space in which the Euclidean distance between any two colors is equal to the perceptual distance, as seen by one individual subject, endowed with an arbitrary number of color-sensitive photoreceptors, each with arbitrary absorption probability curves and appearing in arbitrary proportions.

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Abroskin, Alexander, and Natalia Abroskina. "Problems of Information Support for Social Assistance to the Population During the COVID-19 Pandemic." Sociologicheskaja nauka i social'naja praktika 9, no. 3 (September 30, 2021): 7–24. http://dx.doi.org/10.19181/snsp.2021.9.3.8430.

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The article deals with the actual problems of providing targeted social assistance to the population during the economic crisis. The research subject is a set of measures to stabilize the income of the population, implemented by the Government of the Russian Federation in 2020 during the most acute phase of the crisis associated with the COVID-19 pandemic. The purpose of the research is to analyze and summarize the practice of social assistance to the population, to identify problems and prospects for using the monetary approach to neutralize the negative socio-economic consequences of the restrictions associated with the pandemic. The main aspects of the analysis involve measures to stabilize the income of the population, including measures to support employment in the economy and stabilize labor income, as well as measures of targeted social assistance to households implemented in Russian practice. In the research, the monetary approach is considered in a broad context, extended to the criteria determining the resource provision of households and the population property status, the characteristics underling the households grouping by the degree of need, and targeted assistance measures implemented in the cash transfers form. The results of the research revealed a number of problems with the monetary approach using in the implementation of the anti-crisis strategy in the Russian Federation in its simplified version, focused on the indicators of household monetary income without taking into account other components of disposable resources. Additional challenges in identifying targeted social assistance groups during the pandemic were associated with the established practice of building structural groupings of households, based on the dichromatic principle, as well as the transition from 2021 of russian statistics to the new principles of calculating the minimum subsistence level, which is the basic criterion for determining the property status of the population. Improving the effectiveness of social assistance measures to the population in the Russian Federation during economic crises involves adjusting the existing methodological and information base used in assessing the degree of household need. If detailed statistics are available, the corresponding monetary indicators can serve as an information basis for identifying the objects of targeted social assistance. Such indicators, by analogy with foreign practice, can also be supplemented by non-monetary characteristics that determine the degree of household need on other grounds, on the basis of combination of which their groups can be identified in accordance with the priorities and types of social assistance provided. The article was prepared within the framework of the RANEPA state task research.

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Firas Abbas Hussain Al-saadi. "Histological study to the effect of Potassium Dichromate on the reproductive organs in mature rats." Tikrit Journal of Pure Science 22, no. 5 (January 29, 2023): 93–97. http://dx.doi.org/10.25130/tjps.v22i5.773.

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This study was designed to show the effect of potassium dichromate (24 mg/kg orally for 60 day) in mature male and female. The results of experiment in male rats showed decrease in seminiferous epithelia thickness and number of stage VII cells (spermatogonium, spermatocytes, spermatids) at the same time the experiment of immature female rats treated with potassium dichromate showed increase in the diameter of ovarian follicles in the categories (101-200), (201-300) and (<400) .It was concluded that potassium dichromate has detrimental effects on living tissue and in some sexual parts in both sexes (male and female) .

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Krejčí, R., and M. Palíková. "Potassium Dichromate as a Reference Substance for Embryonic Tests of Toxicity in the Common Carp (Cyprinus carpio L.)." Acta Veterinaria Brno 75, no. 2 (2006): 259–63. http://dx.doi.org/10.2754/avb200675020259.

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Potassium dichromate (K2Cr2O7) has already been used as a reference substance in tests of toxicity with aquatic animals. The aim of this study was to determine and compare values of LC50 for potassium dichromate during the whole period of embryonic development (i.e., 120 h) and 48 h after hatching of embryos in the common carp (Cyprinus carpio L.). Fish eggs and embryos were exposed to 5 different concentrations of potassium dichromate (i.e., 372, 409, 450, 495, 545 mg l-1) during two experiments. Such characteristics as the cumulative mortality, the start and the end of hatching, the number of deformities, body length, and body mass of surviving individuals were studied during the tests. The highest mortality was found in the hatched embryos. Mortality and frequency of deformities increased with the growing concentration of potassium dichromate. The value of 120 LC50 for potassium dichromate was 464.91 ± 23.83 mg l-1 and the value of 48 LC50 was 458.94 ± 4.14 mg l-1 (mean ± SD). No statistically significant difference between values 120 LC50 a 48 LC50 was found. This is why reduction of the exposure period to only 48 h after hatching seems a reasonable method to study the control of susceptibility using potassium dichromate in embryonic tests of toxicity.

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Krupa, Renata, Marcin Stañczak, and Zofia Walter. "Chromium Incorporated in RNA and DNA." Zeitschrift für Naturforschung C 57, no. 9-10 (October 1, 2002): 951–53. http://dx.doi.org/10.1515/znc-2002-9-1033.

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The objective of this study was to examine the effect of Cr(III) (chromium chloride) and Cr(VI) (potassium dichromate) on RNA and DNA-chromium adducts formation in isolated nucleic acids and isolated pig lymphocytes. The incubation of cells with potassium dichromate and chromium chloride at concentrations of 10 and 100 μm results in binding of a 1.2-1.9 fold greater number of chromium atoms to nuclear DNA than to total cellular RNA. The incubation of total cellular RNA and nuclear DNA isolated from lymphocytes with CrCl3 and K2Cr2O7 yielded a binding of 1.1-1.6 fold more of Cr atoms to RNA than to DNA. The number of chromium atoms bound to nucleic acids is higher after incubation with K2Cr2O7 than with CrCl3 in both experimental systems.

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Linhares, João Manuel Maciel, Paulo Daniel Pinto, and Sérgio Miguel Cardoso Nascimento. "The number of colors perceived by dichromats when appreciating art paintings under standard illuminants." Conference on Colour in Graphics, Imaging, and Vision 4, no. 1 (January 1, 2008): 441–43. http://dx.doi.org/10.2352/cgiv.2008.4.1.art00094.

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Kasmiyati, Sri, Santosa S, Irfan Dwidja Priyambada, Kumala Dewi, and Rintawati Sandradewi. "Perkecambahan Biji Dan Pertumbuhan Kecambah Varietas Sorgum (Sorghum bicolor L.) Pada Cekaman Krom Heksavalen." Bioma : Berkala Ilmiah Biologi 17, no. 1 (June 17, 2015): 41. http://dx.doi.org/10.14710/bioma.17.1.41-54.

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In contrast to other toxic trace metals, Cr has received little attention. Since valence level of chromium determines its toxicity, chromium is categorized as unique heavy metal. Chromium hexavalent (Cr6+) has the biggest toxicity among other valence levels. Seed germination and seedling growth are sensitive to heavy metal stresses. This research aimed to find out the responses of seed germination and seedling growth of 12 sorghum varieties toward Cr6+. Seed germination and seedling growth experiment was done on 12 sorghum varieties (Badik, UPCA-1, Keris, Keris M3, hegari Genjah, Gambela, Selayer, Sangkur, Mandau, Batari, Kawali, dan Numbu), planted in petridishes with Cr6+ treatment in form of chromate (K2CrO4) and dichromate (K2Cr2O7) compounds with 0, 50 and 500 mg of Cr/l concentration for a week. The parameters measured were the number of seeds germinate each day; the length of radicle and plumule, and fresh and dry weight at the end of experiment. The results showed that higher concentration of Cr6+ both in form of dichromate and chromate, significantly decreased the length of radicle and plumule, fresh and dry weight, and SVI (seedling vigor index) value. However, index germination (GI) value and percentage of germination of the 12 varieties sorgum significantly increased in the treatment of 50 mg Cr/l Cr6+ in form of dichromate and chromate. The treatment of dichromate compound showed bigger effect than chromate toward variables of seed germination and seedling growth of sorghum. It was noticed that 12 sorghum varieties possessed an integrated complex of adaptation to cope with the range of form of compound and concentration of Cr6+. Based on the responses of seed germination and seedling growth, Kawali, Hegari, Keris, Keris M3, Mandau, and Selayer varieties was more susceptible toward Cr6+ toxicity, and Sangkur, Selayer, Batari, and Numbu was more tolerant than other varieties. Keywords : chromate, dichromate, Sorghum bicolor, seedling, hexavalent chromium

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Sayyah, S. M., A. B. Khaliel, Ahmed A. Aboud, and S. M. Mohamed. "Chemical Polymerization Kinetics of Poly-O-Phenylenediamine and Characterization of the Obtained Polymer in Aqueous Hydrochloric Acid Solution Using K2Cr2O7as Oxidizing Agent." International Journal of Polymer Science 2014 (2014): 1–16. http://dx.doi.org/10.1155/2014/520910.

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The oxidative chemical polymerization of o-phenylenediamine (OPDA) was studied in hydrochloric acid solution using potassium dichromate as oxidant at 5°C. The effects of potassium dichromate, hydrochloric acid, and monomer concentrations on the polymerization reaction were investigated. The order of reaction with respect to potassium dichromate, hydrochloric acid, and monomer concentration was found to be 1.011, 0.954, and 1.045, respectively. Also, the effect of temperature on the polymerization rate was studied and the apparent activation energy of the polymerization reaction was found to be 63.658 kJ/mol. The obtained polymer was characterized using XPS, IR, UV-visible, and elemental analysis. The surface morphology of the obtained polymers was characterized by X-ray diffraction and transmission electron microscopy (TEM). The TGA analysis was used to confirm the proposed structure and number of water molecules in each polymeric chain unit. The ac conductivity(σac)of (POPDA) was investigated as a function of frequency and temperature. The ac conductivity was interpreted as a power law of frequency. The frequency exponent (s) was found to be less than unity and decreased with the increase of temperature, which confirms that the correlated barrier hopping model was the dominant charge transport mechanism.

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GOODALL, ANDREW, THOMAS KRAJEWSKI, GUUS REGTS, and LLUÍS VENA. "A Tutte Polynomial for Maps." Combinatorics, Probability and Computing 27, no. 6 (April 12, 2018): 913–45. http://dx.doi.org/10.1017/s0963548318000081.

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We follow the example of Tutte in his construction of the dichromate of a graph (i.e. the Tutte polynomial) as a unification of the chromatic polynomial and the flow polynomial in order to construct a new polynomial invariant of maps (graphs embedded in orientable surfaces). We call this the surface Tutte polynomial. The surface Tutte polynomial of a map contains the Las Vergnas polynomial, the Bollobás–Riordan polynomial and the Krushkal polynomial as specializations. By construction, the surface Tutte polynomial includes among its evaluations the number of local tensions and local flows taking values in any given finite group. Other evaluations include the number of quasi-forests.

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Falis, Marcel, Michaela Špalková, and Jaroslav Legáth. "Effects of heavy metals and pesticides on survival of Artemia franciscana." Acta Veterinaria Brno 83, no. 2 (2014): 95–99. http://dx.doi.org/10.2754/avb201483020095.

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Assessment of the potential risk of pesticides is an important part of registration procedures in many countries. However, risk assessment of several pesticides used during the growing season has not been carried out. The aim of this study was to investigate the effects of pesticides (azoxystrobin and glyphosate), heavy metals (cadmium chloride, potassium dichromate, zinc disulphate) and their combinations on lethality to Artemia franciscana. In total, 1,250 freshly hatched nauplii of A. franciscana were used in the study. They were placed in 125 Petri dishes (10 nauplii in one Petri dish) containing 10 ml of azoxystrobin, glyphosate, cadmium chloride, potassium dichromate and zinc sulphate separately, or their combinations; the control dish contained only sea water. Each experimental set consisted of 50 nauplii which were divided into five replicates of 10 nauplii per replicate. Live A. franciscana were counted after 24, 48, 72 and 96 h and the numbers were compared with the control group. A significant (P < 0.05) decrease in lethality was observed after exposure to azoxystrobin in combination with glyphosate after 48, 72 and 96 h of exposure, in combination with glyphosate and potassium dichromate after 48 h of exposure, and in combination with glyphosate and zinc disulphate after 48, 72 and 96 h of exposure. The results of this study provide information about the combined toxicity of pesticides used during the growing season and some heavy metals as major pollutants of the rural environment. A study of this kind has not been conducted yet. Further research for investigation of the combined toxicity of pollutants and pesticides is required.

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KURTENBACH, ANNE, JUDITH HEINE, and HERBERT JÄGLE. "Multifocal electroretinogram in trichromat and dichromat observers under cone isolating conditions." Visual Neuroscience 21, no. 3 (May 2004): 249–55. http://dx.doi.org/10.1017/s0952523804213347.

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The aim of this study was to obtain information about single cone class driven activity in the inner and outer retina in humans. We examined outer retinal activity with the multifocal electroretinogram (mfERG) and inner retinal activity using multifocal oscillatory potentials (mfOPs). A standard (black-white) stimulus was used, as well as stimuli aimed at isolating a single photoreceptor class. The results of 10 trichromats were compared to those of 2 protanopes and 2 deuteranopes. At both retinal layers we find that trichromats show cone isolating response amplitudes that reflect the expected number of cones and that single- gene dichromats have a similar total number of functioning cones as trichromats. The ratio of the responses of the L- and M-cones is slightly smaller for the mfOPs than for the mfERGs. The results indicate that there are major changes in the gain of retinal signals after the inner plexiform layer.

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Rana, Arnija, S. Shrestha, AK Jha, DP Thapa, S. Joshi, and B. Amatya. "Study of Common Allergens in Patients with Allergic Contact Dermatitis: A Hospital Based Study." Nepal Medical College Journal 23, no. 1 (April 2, 2021): 16–22. http://dx.doi.org/10.3126/nmcj.v23i1.36222.

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Allergic contact dermatitis (ACD) is one of the most common diseases presenting to the Dermatology department. The one and only method of preventing as well as treating this disease is avoidance of the allergen causing it. The identification of the allergen causing the ACD is possible by performing patch testing. The purpose of this study was to identify common allergens among patients with ACD using Indian standard series (ISS) of patch test. Clinically suspected cases of ACD were included in the hospital based cross-sectional study from January to December 2017. These cases underwent patch testing with the ISS. The study assessed the following variables: sex, age, occupation, site and positive patch test results. There were a total of 58 patients among which, 36.2% were males and 63.8% were females with a mean age of 32.36±12.51 years. Positive patch test reactions were seen in 63.0% of patients. The most common allergens were nickel sulphate (51.4%), fragrance mix (37.8%), potassium dichromate (8.1%), colophony (8.1%) and black rubber mix (8.1%). Among male, most common allergens were fragrance mix (57.1%), nickel sulphate (28.6%) and potassium dichromate (21.4%) while in female, most common allergens were nickel sulphate (65.2%) and fragrance mix (26.1%). In our study, majority of the allergens were positive. Hence, the ISS used in the study might be suitable in the context of Nepalese population. However, further similar studies on large number of patients with multiple allergens are required to determine the exact number of contact allergens prevalent in our population.

Статті в журналах з теми "Dichromatic number"

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