Cone Type Research Articles

Cone types, automata, and regular partitions in Coxeter groups

In this article we introduce the notion of a regular partition of a Coxeter group. We develop the theory of these partitions, and show that the class of regular partitions is essentially equivalent to the class of automata (not necessarily finite state) recognising the language of reduced words in the Coxeter group. As an application of this theory we prove that each cone type in a Coxeter group has a unique minimal length representative. This result can be seen as an analogue of Shi's classical result that each component of the Shi arrangement of an affine Coxeter group has a unique minimal length element. We further develop the theory of cone types in Coxeter groups by identifying the minimal set of roots required to express a cone type as an intersection of half-spaces. This set of boundary roots is closely related to the elementary inversion sets of Brink and Howlett, and also to the notion of the base of an inversion set introduced by Dyer.

Circadian and visual photometry.

Photometry is the metrology of light-optical radiation seen by the human eye due to its action on retinal photoreceptors. Its origins are closely tied to the International Commission on Illumination (CIE), which remains responsible for photometry standards and the language of light used in science and technology. When in 1931 it had become possible to model the response to light of the human eye based on reliable spectroradiometry data, the CIE published standard formulae for predicting the luminance of a stimulus. These and related colorimetry formulae are still in use, having been internationally agreed and adopted. Both fields continue to be the subject of active research and increasing accuracy. CIE S 026:2018 represents another milestone for the metrology of light (CIE, 2018a). It is the first standard where light is considered for its ability to evoke circadian and neurophysiological responses, and includes the spectral sensitivity of melanopsin-a retinal photopigment discovered, and shown to be contributing to and influencing responses from human intrinsically-photosensitive retinal ganglion cells (ipRGCs), only 20 years ago (Berson et al., 2002; Hattar et al., 2002; Provencio et al., 1998). These accessory visual functions also depend to some extent on inputs from the rods and three types of cones; until very recently, rods and cones (or "classical photoreceptors") were the only photoreceptors in visual models. If photometry standards are replaced with modern physiological data, consistent changes should be expected in the photometry of these accessory functions. This chapter outlines the current standards, their definitions and calculations, and how the main elements are related.

Cone distribution and visual resolution of the yellow-legged gull, Larus michahellis (Naumann, 1840).

The morphological characteristics of the yellow-legged gull's photoreceptors and cone distribution were studied using light and electron microscopy. In wholemount fresh retinas, five different coloured oil droplets located in the cone inner segments could be seen and characterized by colour, diameter and stratification. The photoreceptors were classified by comparing the fresh and fixed vertical sections under a light and electron microscope. Rods were easily distinguished from cones based on the outer segment morphology and the absence of oil droplets in their inner segments. Four types of single cones were associated with red, yellow, colourless and transparent oil droplets. Unequal double cones comprised a long principal member with a green oil droplet and an accessory short member containing a green microdroplet which was highly electron-dense under electron microscopy. The different types of oil droplets were counted from microphotographs of fresh retinal samples in 20 regions. The density, percentage and diameter of the oil droplets were determined. The results showed that central regions had the highest oil droplet density which decreased towards the retinal periphery in all quadrants. Moreover, the oil droplet density was higher in the dorsotemporal quadrant than in other retinal regions. The average density of the red oil droplets was highest in the central areas, whereas colourless oil droplets had the highest density throughout the retina. In contrast, transparent oil droplets had the lowest density across all the regions of the retina. Finally, the retinal resolution was 52.61 cycles/degree. It was calculated using the posterior nodal distance and the oil droplet diameter. The work concludes by discussing the significance of the relative proportion of different cone types across the retina.

Moisture diffusion in cement pastes with hydrophobic agent

Hydrophobic treatment of cement pastes is most effective ways to resist the penetration of water with aggressive ions to improve durability of cement-based materials. In this paper, the influence of carboxylic acid ammonium salt integral addition on hydrophobicity of cement-based materials is analyzed. The effects of carboxylic acid ammonium salt on hydrophobicity, moisture diffusion and hydration products are investigated by experimental methods. The results of water vapor sorption isotherm show that the addition of carboxylic acid ammonium salt increases the pore volume. The simplified analytical hydrodynamic model of cone type pore and Young’s relationship is proposed to analyze the relation between characteristic parameters of pore and the permeability of cementitious materials. It can be concluded that the hydrophobicity results from the change of pore structure and the hydrophobic surface of cone region. These results provide the guidance to design the durability and to develop the new hydrophobic agent used in cementitious material.

Ultrastructure of the larval eyes of the hangingfly Terrobittacus implicatus (Mecoptera: Bittacidae)

The fine structure of the larval eyes of the hangingfly Terrobittacus implicatus (Huang & Hua) was investigated using scanning and transmission electron microscopy. The results show that the larval eyes of T. implicatus each consist of seven spaced ommatidia. Each ommatidium is composed of a corneal lens with about 45 lamellae, a tetrapartite eucone type of crystalline cone, eight retinula cells, two primary pigment cells, and an undetermined number of secondary pigment cells. The rhabdomeres of eight retinula cells effectively fuse into a centrally-fused, tiered funnel-shaped rhabdom extending from the base of the crystalline cone deeply into the ommatidium. In light of different positions in the ommatidium, the retinula cells can be divided into four distal and four proximal retinula cells. Pigment cells envelop the entire ommatidium. Electron-lucent vesicles are abundant throughout the cytoplasm of the eight retinula cells. The larval ommatidia of T. implicatus are similar to those of the Panorpidae, except for the distal retinula cells that also participate in the formation of the proximal rhabdom. In this case, the larval eyes of T. implicatus may lie in the transitional stage during the larval eye evolution of insects from ommatidia to stemmata.

Structural parameters and critical anchorage length of tunnel system bolts made of basalt fibre

Basalt fibre reinforced polymer (BFRP) has the advantages of high tensile strength and good durability; therefore, the anchor bolt developed with BFRP has potential application in tunnel surrounding rock anchorage. This study used meso-scale numerical simulation and laboratory tests to examine the structural parameters of BFRP anchor plate and rod and the critical anchorage length of BFRP cement mortar anchor. The results showed that: 1) the special-shaped truncated cone type anchor plate can convert the axial force into internal tensile stress, which improves the tensile performance of the basalt fibre material. 2) The larger the thread pitch of the BFRP bolt or the smaller the thread height, the more uniform is the shear stress distribution of the bolt thread, and the smaller is the maximum shear stress of the rod and nut. 3) The thread height of 2 mm and thread pitch of 18 mm is the optimal combination. 4) The critical anchoring length of the BFRP cement mortar bolt is 20–40 times its diameter. The findings of this study can provide new and meaningful reference for the application of System Bolts made of Basalt Fiber in tunnel engineering.

Accurate Estimations of Any Eigenpairs of N-th Order Linear Boundary Value Problems

This paper provides a method to bound and calculate any eigenvalues and eigenfunctions of n-th order boundary value problems with sign-regular kernels subject to two-point boundary conditions. The method is based on the selection of a particular type of cone for each eigenpair to be determined, the recursive application of the operator associated to the equivalent integral problem to functions belonging to such a cone, and the calculation of the Collatz–Wielandt numbers of the resulting functions.

Spectral inference reveals principal cone-integration rules of the zebrafish inner retina

SummaryRetinal bipolar cells integrate cone signals at dendritic and axonal sites. The axonal route, involving amacrine cells, remains largely uncharted. However, because cone types differ in their spectral sensitivities, insights into bipolar cells’ cone integration might be gained based on their spectral tunings. We therefore recorded in vivo responses of bipolar cell presynaptic terminals in larval zebrafish to widefield but spectrally resolved flashes of light and mapped the results onto spectral responses of the four cones. This “spectral circuit mapping” allowed explaining ∼95% of the spectral and temporal variance of bipolar cell responses in a simple linear model, thereby revealing several notable integration rules of the inner retina. Bipolar cells were dominated by red-cone inputs, often alongside equal sign inputs from blue and green cones. In contrast, UV-cone inputs were uncorrelated with those of the remaining cones. This led to a new axis of spectral opponency where red-, green-, and blue-cone “Off” circuits connect to “natively-On” UV-cone circuits in the outermost fraction of the inner plexiform layer—much as how key color opponent circuits are established in mammals. Beyond this, and despite substantial temporal diversity that was not present in the cones, bipolar cell spectral tunings were surprisingly simple. They either approximately resembled both opponent and non-opponent spectral motifs already present in the cones or exhibited a stereotyped non-opponent broadband response. In this way, bipolar cells not only preserved the efficient spectral representations in the cones but also diversified them to set up a total of six dominant spectral motifs, which included three axes of spectral opponency.

Evidence of regional specializations in regenerated zebrafish retina

Adult zebrafish are capable of functional retinal regeneration following damage. A goal of vision science is to stimulate or permit a similar process in mammals to treat human retinal disease and trauma. Ideally such a process would reconstitute the stereotyped, two-dimensional topographic patterns and regional specializations of specific cell types, functionally important for representation of the visual field. An example in humans is the cone-rich fovea, essential for high-acuity color vision. Stereotyped, global topographic patterns of specific retinal cell types are also found in zebrafish, particularly for cone types expressing the tandemly-replicated lws (long wavelength-sensitive) and rh2 (middle wavelength-sensitive) opsins. Here we examine whether regionally specialized patterns of LWS1 and LWS2 cones are restored in regenerated retinas in zebrafish. Adult transgenic zebrafish carrying fluorescent reporters for lws1 and lws2 were subjected to retinal lesions that destroy all neurons but spare glia, via intraocular injection of the neurotoxin ouabain. Regenerated and contralateral control retinas were mounted whole or sectioned, and imaged. Overall spatial patterns of lws1 vs. lws2 opsin-expressing cones in regenerated retinas were remarkably similar to those of control retinas, with LWS1 cones in ventral/peripheral regions, and LWS2 cones in dorsal/central regions. However, LWS2 cones occupied a smaller fraction of regenerated retina, and several cones co-expressed the lws1 and lws2 reporters in regenerated retinas. Local patterns of regenerated LWS1 cones showed modest reductions in regularity. These results suggest that some of the regional patterning information, or the source of such signals, for LWS cone subtypes may be retained by undamaged cell types (Müller glia or RPE) and re-deployed during regeneration.

Evolutionary adaptation of visual pigments in geckos for their photic environment.

Vertebrates generally have a single type of rod for scotopic vision and multiple types of cones for photopic vision. Noteworthily, nocturnal geckos transmuted ancestral photoreceptor cells into rods containing not rhodopsin but cone pigments, and, subsequently, diurnal geckos retransmuted these rods into cones containing cone pigments. High sensitivity of scotopic vision is underlain by the rod’s low background noise, which originated from a much lower spontaneous activation rate of rhodopsin than of cone pigments. Here, we revealed that nocturnal gecko cone pigments decreased their spontaneous activation rates to mimic rhodopsin, whereas diurnal gecko cone pigments recovered high rates similar to those of typical cone pigments. We also identified amino acid residues responsible for the alterations of the spontaneous activation rates. Therefore, we concluded that the switch between diurnality and nocturnality in geckos required not only morphological transmutation of photoreceptors but also adjustment of the spontaneous activation rates of visual pigments.

Ganglion cells in larval zebrafish retina integrate inputs from multiple cone types.

We recently showed the presence of seven physiological cone opsins-R1 (575 nm), R2 (556 nm), G1 (460 nm), G3 (480 nm), B1 (415 nm), B2 (440 nm), and UV (358 nm)-in electroretinogram (ERG) recordings of larval zebrafish (Danio rerio) retina. Larval ganglion cells (GCs) are generally thought to integrate only four cone opsin signals (red, green, blue, and UV). We address the question as to whether they may integrate seven cone spectral signals. Here we examined the 127 possible combinations of seven cone signals to find the optimal representation, as based on impulse discharge data sets from GC axons in the larval optic nerve. We recorded four varieties of light-response waveform, sustained-ON, transient-ON, ON-OFF, and OFF, based on the time course of mean discharge rates to all stimulus wavelengths combined. Modeling of GC responses revealed that each received 1-6 cone opsin signals, with a mean of 3.8 ± 1.3 cone signals/GC. Most onset or offset responses were opponent (ON, 80%; OFF, 100%). The most common cone signals were UV (93%), R2 (50%), G3 (55%), and G1 (60%). Seventy-three percent of cone opsin signals were excitatory, and 27% were inhibitory. UV signals favored excitation, whereas G3 and B2 signals favored inhibition. R1/R2, G1/G3, and B1/B2 opsin signals were selectively associated along a nonsynergistic/opponent axis. Overall, these results suggest that larval zebrafish GC spectral responses are complex and use inputs from the seven expressed opsins.NEW & NOTEWORTHY Ganglion cells in larval zebrafish retina have complex spectral responses driven by seven different cone opsin types. UV cone inputs are significant and excitatory to ganglion cells, whereas green and blue cone inputs favor inhibition. Most dramatic are the pentachromatic cells. These responses were identified at 5-6 days after fertilization, reflecting an impressive level of color processing not seen in older fish or mammals.

Morpho-anatomical affinities and evolutionary relationships of three paleoendemic podocarp genera based on seed cone traits.

The three relict genera Pherosphaera, Microcachrys and Saxegothaea in Podocarpaceae produce quite distinct seed cone types in comparison with other genera and do not form a clade along with Acmopyle. The detailed seed cone morpho-anatomy of these three relict genera and affinities with other podocarps are poorly known. This study aims to understand the seed cone morpho-anatomy and affinities among these three disjunct relict genera and with other podocarps. We comparatively analysed the seed cone morpho-anatomical traits of the three podocarps genera and used ancestral state reconstruction to understand the evolution of these traits. We described the seed cone morpho-anatomical structures of the three relict genera in detail. The three genera produce aggregated multiovulate cones. Both Microcachrys and Saxegothaea have an asymmetrical free cup-like epimatium. Both species of Pherosphaera lack an epimatium. The ancestral state reconstruction implies that the presence of an epimatium is an ancestral trait in podocarps and is independently lost in Pherosphaera and Phyllocladus. The seed cones are fleshy in Microcachrys and non-fleshy in Saxegothaea and Pherosphaera. The seed cone macrofossils of both extinct and living podocarps also show the presence of an epimatium and fleshiness in podocarps. Altogether, the morpho-anatomy suggests that Pherosphaera, Microcachrys and Saxegothaea present affinities with each other and other podocarps, but the reconstruction of the ancestral seed cone in Podcarpaceae is quite complex due to multiple convergent evolutions of several structures. These structures (e.g. epimatium, aril and receptaculum) are of low taxonomic value but of great evolutionary and ecological significance, and are responsive adaptations to ever-changing environmental conditions.

Research on Water Invasion Mode and Water Control Counter Measures of Geological MX Gas Reservoir

The MX gas reservoir is a typical carbonate gas reservoir and there are three types of water production characteristics in producing wells during the development process: fast rising type, slow rising type and stable type. The overall water invasion mode is dominated by the edge water invasion mode, with four types of water invasion modes including bottom water cone type, edge water finger type, edge water tongue type and native movable water tongue type. In this paper, numerical simulation techniques are used to investigate water management countermeasures for MX gas reservoirs based on the dynamic identification of water invasion. The results show that, after optimisation of the drainage and water control plans, the gas reservoir can produce steadily until the end of 2025 at a recovery rate of 3.06%, extending the time of steady production by about 9 months. In view of the relatively uniform advancement of fracture water channel and edge water into the interior of the gas reservoir, it is feasible to adopt active drainage and edge water control measures respectively to reduce the risk of water intrusion in the gas reservoir and ensure stable gas production.

Partitioning of gene expression among zebrafish photoreceptor subtypes

Vertebrate photoreceptors are categorized into two broad classes, rods and cones, responsible for dim- and bright-light vision, respectively. While many molecular features that distinguish rods and cones are known, gene expression differences among cone subtypes remain poorly understood. Teleost fishes are renowned for the diversity of their photoreceptor systems. Here, we used single-cell RNA-seq to profile adult photoreceptors in zebrafish, a teleost. We found that in addition to the four canonical zebrafish cone types, there exist subpopulations of green and red cones (previously shown to be located in the ventral retina) that express red-shifted opsin paralogs (opn1mw4 or opn1lw1) as well as a unique combination of cone phototransduction genes. Furthermore, the expression of many paralogous phototransduction genes is partitioned among cone subtypes, analogous to the partitioning of the phototransduction paralogs between rods and cones seen across vertebrates. The partitioned cone-gene pairs arose via the teleost-specific whole-genome duplication or later clade-specific gene duplications. We also discovered that cone subtypes express distinct transcriptional regulators, including many factors not previously implicated in photoreceptor development or differentiation. Overall, our work suggests that partitioning of paralogous gene expression via the action of differentially expressed transcriptional regulators enables diversification of cone subtypes in teleosts.

Vertical Discrepancy in Height of Morse Cone Abutments Submitted to Different Torque Forces.

The present study aimed to evaluate the influence of manual torque (10 Ncm) versus clinical torque (30 Ncm), which is recommended by the manufacturer, on the total length of morse cone implant abutments. Twenty specimens were prepared and distributed into two groups: group 1 with ten analogs for morse cone type implant, and group 2 with ten morse type implants, size 4.3 × 15 cm. In each group, the distance between the implant platform to the top of the prosthetic abutment (abutment height) was measured and subjected to a torque of 10 Ncm. Then, the 30 Ncm torque was applied to the same abutment, and abutment height was measured. The distance between the top of the abutment and the implant/analog base was measured. In order to verify the clinical reproducibility of the experiment, comparisons between the abutment height of the analog at 10 Ncm and the implant at 30 Ncm were performed, showing a greater discrepancy in torque for the 10 Ncm analog (p < 0.05). In order to verify if the change in the laboratory protocol from 10 to 30 Ncm could minimize the differences in the height of the prosthetic abutments, the abutment height in groups 1 and 2 was compared with 30 Ncm, and no significant difference was observed (p > 0.05). The data indicated that the manual torque and the torque recommended by the manufacturer influence the total length of the prosthetic abutments of morse cone implants.

Statistical Properties of Color Matching Functions.

In trichromats, color vision entails the projection of an infinite-dimensional space (the one containing all possible electromagnetic power spectra) onto the three-dimensional space that modulates the activity of the three types of cones. This drastic reduction in dimensionality gives rise to metamerism, that is, the perceptual chromatic equivalence between two different light spectra. The classes of equivalence of metamerism are revealed by color-matching experiments in which observers adjust the intensity of three monochromatic light beams of three preset wavelengths (the primaries) to produce a mixture that is perceptually equal to a given monochromatic target stimulus. Here we use the linear relation between the color matching functions and the absorption probabilities of each type of cone to find particularly useful triplets of primaries. As a second goal, we also derive an analytical description of the trial-to-trial variability and the correlations of color matching functions stemming from Poissonian noise in photon capture. We analyze how the statistical properties of the responses to color-matching experiments vary with the retinal composition and the wavelengths of peak absorption probability, and compare them with experimental data on subject-to-subject variability obtained previously.

Electrophysiological evidence for higher-level chromatic mechanisms in humans.

Color vision in humans starts with three types of cones (short [S], medium [M], and long [L] wavelengths) in the retina and three retinal and subcortical cardinal mechanisms, which linearly combine cone signals into the luminance channel (L + M), the red-green channel (L – M), and the yellow-blue channel (S-(L + M)). Chromatic mechanisms at the cortical level, however, are less well characterized. The present study investigated such higher-order chromatic mechanisms by recording electroencephalograms (EEGs) on human observers in a noise masking paradigm. Observers viewed colored stimuli that consisted of a target embedded in noise. Color directions of the target and noise varied independently and systematically in an isoluminant plane of color space. The target was flickering on-off at 3 Hz, eliciting steady-state visual evoked potential (SSVEP) responses. As a result, the masking strength could be estimated from the SSVEP amplitude in the presence of 6 Hz noise. Masking was strongest (i.e. target eliciting smallest SSVEPs) when the target and noise were along the same color direction, and was weakest (i.e. target eliciting highest SSVEPs) when the target and noise were along orthogonal directions. This pattern of results was observed both when the target color varied along the cardinal and intermediate directions, which is evidence for higher-order chromatic mechanisms tuned to intermediate axes. The SSVEP result can be well predicted by a model with multiple broadly tuned chromatic mechanisms. In contrast, a model with only cardinal mechanisms failed to account for the data. These results provide strong electrophysiological evidence for multiple chromatic mechanisms in the early visual cortex of humans.

Indoor Air Quality: Assessment of Dangerous Substances in Incense Products.

Indoor air pollution has obtained more attention in a moment where “stay at home” is a maximum repeated for the entire world. It is urgent to know the sources of pollutants indoors, to improve the indoor air quality. This study presents some results obtained for twelve incense products, used indoors, at home, and in temples, but also in spa centers or yoga gymnasiums, where the respiratory intensity is high, and the consequences on health could be more severe. The focus of this study was the gaseous emissions of different types of incense, performing a VOC screening and identifying some specific VOCs different from the usual ones, which are known or suspected to cause severe chronic health effects: carcinogenic, mutagenic, and reprotoxic. Thirteen compounds were selected: benzene, toluene, styrene, naphthalene, furfural, furan, isoprene, 2-butenal, phenol, 2-furyl methyl ketone, formaldehyde, acetaldehyde, and acrolein. The study also indicated that incense cone type shows a higher probability of being more pollutant than incense stick type, as from the 12 products tested, four were cone type, and three of them were in the group of the four higher polluters. Benzene and formaldehyde presented worrying levels in the major part of the products, above guideline values established by the WHO. Unfortunately, there are no limit values established for indoor air for all the compounds studied, but this fact should not exempt us from taking action to alert the population to the potential dangers of using those products. From this study, acetaldehyde, acrolein, furfural, and furan emerge as compounds with levels to deserve attention.

Intermixing the OPN1LW and OPN1MW Genes Disrupts the Exonic Splicing Code Causing an Array of Vision Disorders.

Light absorption by photopigment molecules expressed in the photoreceptors in the retina is the first step in seeing. Two types of photoreceptors in the human retina are responsible for image formation: rods, and cones. Except at very low light levels when rods are active, all vision is based on cones. Cones mediate high acuity vision and color vision. Furthermore, they are critically important in the visual feedback mechanism that regulates refractive development of the eye during childhood. The human retina contains a mosaic of three cone types, short-wavelength (S), long-wavelength (L), and middle-wavelength (M) sensitive; however, the vast majority (~94%) are L and M cones. The OPN1LW and OPN1MW genes, located on the X-chromosome at Xq28, encode the protein component of the light-sensitive photopigments expressed in the L and M cones. Diverse haplotypes of exon 3 of the OPN1LW and OPN1MW genes arose thru unequal recombination mechanisms that have intermixed the genes. A subset of the haplotypes causes exon 3- skipping during pre-messenger RNA splicing and are associated with vision disorders. Here, we review the mechanism by which splicing defects in these genes cause vision disorders.

Multiple Dirac cones and Lifshitz transition in a two-dimensional Cairo lattice as a Hawking evaporation analogue

The linear energy–momentum dispersion of Dirac cones offers a unique platform for mimicking the fantastical phenomena in high energy physics, such as Dirac fermions and black hole (BH) horizons. Three types of Dirac cones (I, III, and II) with different tilts have been proposed individually in specific materials but lack of integral lattice model. Here, we demonstrated the three types of Dirac cones inherited in a π-conjugated Cairo lattice of double-degenerate d π and p z orbitals by means of tight-binding (TB) approach, which paves a way for the design of two-dimensional (2D) Dirac materials. From first-principles calculations, we predicted a candidate material, penta-NiSb2 monolayer, to achieve these multiple Dirac cones and the Lifshitz transition between different Dirac cones driven by external biaxial strain. The coexistence of the three types of Dirac cones renders penta-NiSb2 monolayer a promising 2D fermionic analogue to simulate the event-horizon evaporation with a high Hawking temperature.