Vertical Stripes Research Articles

Line Segmentation of Devanagari Ancient Manuscripts

In this paper, we have proposed a line segmentation algorithm for Devanagari ancient documents by dividing the document image into vertical stripes and followed by piecewise horizontal projection profiles. Average line height is computed, and based on this height, under-segmentation or over-segmentation of lines is detected for ancient manuscripts recognition. For experimental work of line segmentation algorithm, Devanagari ancient manuscripts are collected from various libraries and museums. To digitize these images, scanner and digital camera are used. The proposed line segmentation algorithm is tested on 1500 text lines. To the best of our knowledge, this is the first work of its kind for line segmentation on Devanagari ancient manuscripts. The proposed algorithm can be used for other Indian scripts also.

Effects of time-periodic forcing in a Cahn-Hilliard model for Langmuir-Blodgett transfer.

The influence of a temporal forcing on the pattern formation in Langmuir-Blodgett transfer is studied employing a generalized Cahn-Hilliard model. The occurring frequency-locking effects allow for controlling the pattern formation process. In the case of one-dimensional (i.e., stripe) patterns one finds various synchronization phenomena such as entrainment between the distance of deposited stripes and the forcing frequency. In two dimensions, the temporal forcing gives rise to the formation of intricate complex patterns such as vertical stripes, oblique stripes, and lattice structures. Remarkably, it is possible to influence the system in the spatial direction perpendicular to the forcing direction leading to synchronization in two spatial dimensions.

Insect Neurobiology: What to Make of a Small Spot?

Vertical stripes have long been known to attract laboratory fruit flies, but small spots, presumably common in the wild, seemed only to avert them. A new study finds odor can reverse this, demonstrating that flies respond to shapes more judiciously than was thought.

A story of nasal horns: two new subspecies of Iguana Laurenti, 1768 (Squamata, Iguanidae) in Saint Lucia, St Vincent amp; the Grenadines, and Grenada (southern Lesser Antilles).

The Lesser Antilles, in the Eastern Caribbean, were long considered to have only two species in the genus Iguana Laurenti 1768: the Lesser Antillean iguana Iguana delicatissima, which is endemic to parts of the Lesser Antilles, and the Common green iguana Iguana iguana, which also occurs throughout Central and South America. No subspecies are currently recognised. However, herpetologists and reptile collectors have pointed out strong physical differences between some of the island populations of Iguana iguana and those from the continent. Drawing on both morphological and genetic data, this paper describes two subspecies of the Common green iguana Iguana iguana from the southern Lesser Antilles, specifically the countries of Saint Lucia Iguana iguana sanctaluciae and Iguana iguana insularis from St Vincent the Grenadines, and Grenada. The form on the island of Saint Vincent has not been identified. The new subspecies are described based on the following unique combination of characters: Presence of high median and medium to small lateral horns on the snout; Small subtympanic plate not exceeding 20% of the eardrum size; Two or three scales of decreasing size anterior to the subtympanic plate; Fewer than ten small to medium triangular gular spikes; Medium sized dewlap; Low number of small to medium dispersed nuchal tubercles; Dark brown iris, with the white of the eye visible; Oval, prominent nostril; Short and relatively flat head; High dorsal spines; No swelling of the jowls in reproductively active males. Iguana iguana sanctaluciae has in adults vertical black stripes on body and tail and a black dewlap whereas Iguana iguana insularis is pale grey or creamy white in adults. Both subspecies are globally threatened by unsustainable hunting (including the pet trade) and by invasive alien species, including hybridization from invasive iguanas from South and Central America (I. iguana iguana and I. rhinolopha, considered here as full species) that have become established in all three countries. The authors call for stronger measures to conserve the remaining purebred Iguana i. insularis and Iguana i. sanctaluciae ssp. nov. throughout their ranges and for further research to identify other cryptic species and subspecies of Iguana in the Lesser Antilles.

Drop flow method: an iterative algorithm for complete segmentation of Devanagari ancient manuscripts

One of the major challenges of ancient manuscripts recognition is character segmentation. Because of many distinct features of ancient documents (thick characters, overlapping and touching characters), character segmentation is a very difficult task. Devanagari ancient manuscripts consist of vowels, consonants, modifiers, conjuncts and compound characters. Using existing techniques, segmentation of overlapping and touching characters is problematic. In this paper, an iterative character segmentation algorithm is presented for ancient documents in Devanagari script. At the beginning, the lines are extracted from the ancient documents by dividing the document image into vertical stripes and then using piecewise horizontal projection profiles. After that, these lines are segmented into words using vertical projection profiles and finally, words are segmented in characters using an iterative algorithm. In each iteration, character segmentation is refined. In the present work, we have proposed a new algorithm with the name ‘Drop Flow Method’ to find the segmentation path between touching components. The proposed algorithm can segment touching characters and 96.0% accuracy has been achieved for complete segmentation of Devanagari ancient manuscripts.

Real-space observation of charge ordering in epitaxial La2\u2212xSrxCuO4 films

The cuprate superconductors exhibit ubiquitous instabilities toward charge-ordered states. These unusual electronic states break the spatial symmetries of the host crystal, and have been widely appreciated as essential ingredients for constructing a theory for high-temperature superconductivity in cuprates. Here, we report real-space imaging of the doping-dependent charge orders in the epitaxial thin films of a canonical cuprate compound La2–xSrxCuO4 using scanning tunneling microscopy. As the films are moderately doped, we observe a crossover from incommensurate to commensurate (4a0, where a0 is the Cu–O–Cu distance) stripes. Furthermore, at lower and higher doping levels, the charge orders occur in the form of distorted Wigner crystal and grid phase of crossed vertical and horizontal stripes. We discuss how the charge orders are stabilized, and their interplay with superconductivity.

Half-filled stripes in a hole-doped three-orbital spin-fermion model for cuprates

Using Monte Carlo techniques, we study a three-orbital ${\mathrm{CuO}}_{2}$ spin-fermion model for copper-based high-critical-temperature superconductors that captures the charge-transfer properties of these compounds. Our studies reveal the presence of spin order in the parent compound and, more importantly, stripe spin and charge order under hole doping. Due to the $p\text{\ensuremath{-}}d$ orbital hybridization, the added holes are approximately equally distributed among the two $p$ orbitals of the oxygen atoms and the $d$ orbital of the copper atoms in the unit cell. In rectangular clusters of dimension $16\ifmmode\times\else\texttimes\fi{}4$ half-filled stripes are observed upon hole doping; namely, when ${N}_{h}=2n$ holes are introduced in the system, then $n$ vertical stripes of length 4 along the short periodic direction are formed. The original antiferromagnetic order observed in the parent compound develops a $\ensuremath{\pi}$ shift across each stripe, and the magnetic structure factor has a peak at wave vector $\mathbf{k}=(\ensuremath{\pi}\ensuremath{-}\ensuremath{\delta},\ensuremath{\pi})$ with $\ensuremath{\delta}=2\ensuremath{\pi}{N}_{h}/N=\ensuremath{\pi}{N}_{h}/2L$, where $L=16$. The electronic charge is also modulated, and the charge structure factor is maximized at $\mathbf{k}=(2\ensuremath{\delta},0)$. As electrons are removed from the system, intracell orbital nematicity with $\ensuremath{\langle}{n}_{{p}_{x}}\ensuremath{\rangle}\ensuremath{-}\ensuremath{\langle}{n}_{{p}_{y}}\ensuremath{\rangle}\ensuremath{\ne}0$ develops in the oxygen sector, as well as intercell magnetic nematicity with $\ensuremath{\langle}{S}_{\mathbf{i},d}^{z}({S}_{\mathbf{i}+\mathbf{x},d}^{z}\ensuremath{-}{S}_{\mathbf{i}+\mathbf{y},d}^{z})\ensuremath{\rangle}\ensuremath{\ne}0$ in the spin copper sector, in the standard notation. This occurs not only in rectangular but also in square $8\ifmmode\times\else\texttimes\fi{}8$ lattices. Our results suggest that the essence of the stripe spin and charge distribution experimentally observed in hole-doped cuprates is captured by unbiased Monte Carlo studies of a simple hole-doped charge-transfer insulator ${\mathrm{CuO}}_{2}$ spin-fermion model.

The contrast sensitivity function of a small cryptobenthic marine fish.

Spatial resolution is a key property of eyes when it comes to understanding how animals' visual signals are perceived. This property can be robustly estimated by measuring the contrast sensitivity as a function of different spatial frequencies, defined as the number of achromatic vertical bright and dark stripe pairs within one degree of visual angle. This contrast sensitivity function (CSF) has been estimated for different animal groups, but data on fish are limited to two free-swimming, freshwater species (i.e., goldfish and bluegill sunfish). In this study, we describe the CSF of a small marine cryptobenthic fish (Tripterygion delaisi) using an optokinetic reflex approach. Tripterygion delaisi features a contrast sensitivity that is as excellent as other fish species, up to 125 (reciprocal of Michelson contrast) at the optimal spatial frequency of 0.375 c/°. The maximum spatial resolution is instead relatively coarse, around 2.125 c/°. By comparing our results with acuity values derived from anatomical estimates of ganglion cells' density, we conclude that the optokinetic reflex seems to be adapted to process low spatial frequency information from stimuli in the peripheral visual field and show that small marine fish can feature excellent contrast sensitivity at optimal spatial frequency.

Dyslexic individuals orient but do not sustain visual attention: Electrophysiological support from the lower and upper alpha bands

Individuals with developmental dyslexia have been characterized by problems with attentional orienting. In the current study, we specifically focused on possible changes in endogenous visual orienting that may be reflected in the electroencephalogram. A variant of the Posner cuing paradigm was employed with valid or invalid central cues that preceded target stimuli that were presented in the left or right visual field. The target stimuli consisted of vertical or horizontal stripes with low (two thick lines) or high (six thin lines) spatial frequencies. We examined lateralized alpha power in the cue-target interval as recent studies revealed that a contra vs. ipsilateral reduction in alpha power relates to the orienting of attention. An initial orienting effect in the lower alpha band was more pronounced for dyslexic individuals than for controls, suggesting that they oriented at an earlier moment in time. However, in contrast with controls, at the end of the cue-target interval no clear contralateral reduction in the upper alpha band was observed for dyslexic individuals. Dyslexic individuals additionally displayed slower responses, especially for invalidly cued high spatial frequency targets in the left visual field. The current data support the view that dyslexic individuals orient well to the cued location but have a problem with sustaining their attention.

Ring Artifacts Reduction in CBCT: Pixels Detection and Patch Based Correction

The ring artifacts introduced by the defective pixels with non-linear responses in the high-resolution detector, have a great impact on subsequent processing and quantitative analysis of the reconstructed images. In this paper, a multistep method is proposed to suppress the ring artifacts of micro CT images, which firstly locates the positions of the defective pixels in the sinogram, and then corrects the corresponding value in the projections. Since the defective pixels always appear as vertical stripes in the sinogram, a horizontal curve is derived by summing the pixel values along vertical direction, thus the abrupt segments related to the defective stripes are enhanced notably, and a proportion coefficient based on the second derivative of the curve is taken as the indicator for the position and the severity of the defective pixels. Then, the detected defective pixels in the sinogram are transferred and relocated in the projections, an improved 3D block matching filtering (BM3D) algorithm is applied to restore the defective pixels in corresponding projection images. In the end, the tomographic images are reconstructed from the corrected projections. In the experiment, a small piece of the motherwort’s rhizome and a part of a mouse’s lung are imaged by micro-CT, and the result shows that, compared with the other four state-of-art methods, the proposed method has a great reduction on the ring artifacts of the reconstructed images, and makes less impact in spatial resolution and contrast in the same time.

Modeling optimizes the effect of the vertical stripe illusion for foot clearance on upstairs

Modeling optimizes the effect of the vertical stripe illusion for foot clearance on upstairs

A new species of frog-biting midge from Papua New Guinea with a key to the described Corethrellidae of the Australopapuan region (Diptera, Corethrellidae, Corethrella).

Corethrellaoppositophila Kvifte & Bernal, sp. n. is described based on one male and six female specimens collected at 2200 m a.s.l. on Mount Wilhelm, Papua New Guinea. The species is the fourth species of frog-biting midge described from this country and appears similar to Corethrellasolomonis Belkin based on pigmentation of legs and abdominal tergites. It differs from C.solomonis, however, in the shape of female flagellomeres I–III, and in the thorax which has a dark brown vertical stripe. The new species is named for its sexually dimorphic flagellomeres, which are short and squat in the female and elongate in the male. These differences in morphological characters are discussed in light of the likely sexual differences in functional uses of the antennae, as males use them for mating only whereas females use them both for mating and prey location. An emended key is presented to the described Australopapuan species of Corethrellidae.

Reliable detection of low visual acuity in mice with pattern visually evoked potentials

Measuring the optokinetic response (OKR) to rotating sinusoidal gratings is becoming an increasingly common method to determine visual function thresholds in mice. This is possible also through direct electrophysiological recording of the response of the neurons in the visual cortex to the presentation of reversing patterned stimuli, i.e. the pattern visually evoked potential (pVEP). Herein, we optimized the conditions for recording pVEPs in wild-type mice: we investigated the optimal depth (1, 2, or 3 mm) of the inserted electrode and the optimal stimulus pattern (vertical, horizontal, or oblique black and white stripes, or a checkerboard pattern). Visual acuity was higher when measured with the optimal pVEP recording conditions, i.e., with the electrode at 2 mm and a vertical-stripe stimulus (0.530 ± 0.021 cycle/degree), than with OKR (0.455 ± 0.006 cycle/degree). Moreover, in murine eyes with optic nerve crush-induced low vision, OKR could not measure any visual acuity, while pVEPs allowed the reliable quantification of residual vision (0.064 ± 0.004 cycle/degree). Our results show that pVEPs allow more sensitive measurement of visual function than the OKR-based method. This technique should be particularly useful in mouse models of ocular disease and low vision.

Ontogenetic and phylogenetic simplification during white stripe evolution in clownfishes

BackgroundBiologists have long been fascinated by the striking diversity of complex color patterns in tropical reef fishes. However, the origins and evolution of this diversity are still poorly understood. Disentangling the evolution of simple color patterns offers the opportunity to dissect both ultimate and proximate causes underlying color diversity.ResultsHere, we study clownfishes, a tribe of 30 species within the Pomacentridae that displays a relatively simple color pattern made of zero to three vertical white stripes on a dark body background. Mapping the number of white stripes on the evolutionary tree of clownfishes reveals that their color pattern diversification results from successive caudal to rostral losses of stripes. Moreover, we demonstrate that stripes always appear with a rostral to caudal stereotyped sequence during larval to juvenile transition. Drug treatments (TAE 684) during this period leads to a dose-dependent loss of stripes, demonstrating that white stripes are made of iridophores and that these cells initiate the stripe formation. Surprisingly, juveniles of several species (e.g., Amphiprion frenatus) have supplementary stripes when compared to their respective adults. These stripes disappear caudo-rostrally during the juvenile phase leading to the definitive color pattern. Remarkably, the reduction of stripe number over ontogeny matches the sequences of stripe losses during evolution, showing that color pattern diversification among clownfish lineages results from changes in developmental processes. Finally, we reveal that the diversity of striped patterns plays a key role for species recognition.ConclusionsOverall, our findings illustrate how developmental, ecological, and social processes have shaped the diversification of color patterns during the radiation of an emblematic coral reef fish lineage.

The Role of Acetylcholine in Attention in Turtles (Chrysemys picta)

Research on mammals and turtles has suggested that acetylcholine is involved in attention in these groups. Two experiments investigated the ability of painted turtles (Chrysemys picta) to ignore irrelevant stimuli when the basal forebrain acetylcholine system was compromised. In experiment 1, turtles given lesions of the basal magnocellular cholinergic nucleus (NBM) or sham lesions were tested on a go/no go discrimination between horizontal and vertical stripes with or without irrelevant inserts in the box. The irrelevant inserts were blue and white checked walls and green carpet on the floor. The group with lesions of the NBM and no irrelevant inserts had no difficulty learning the task, but the lesioned group with irrelevant inserts was impaired on the discrimination. The sham-lesioned group was not impaired by the presence of irrelevant inserts. In experiment 2, turtles were given either the acetylcholine muscarinic receptor blocker scopolamine or saline and tested on the same task. The turtles given scopolamine had no difficulty learning the task in the absence of irrelevant inserts, but they were severely impaired when irrelevant inserts were present. The irrelevant inserts did not affect the learning of control turtles given saline. These findings provide evidence that acetylcholine enhances turtles’ ability to orient to relevant stimuli and suggest that its role in learning and memory may be to allow animals to orient to the stimuli relevant to a task and to ignore irrelevant stimuli.

Feature enhancement for a defocusing structured-light 3-D scanning system

Structured-light systems consisting of a camera and projector are powerful and cost-effective tools for three-dimensional (3-D) shape measurements. However, most commercial projectors are unable to generate distinct patterns due to defocusing and shallow focusing issues. We propose a hybrid method for enhancing the calibration and scanning features of the defocusing structured-light 3-D scanning system. Instead of using conventional sequential binary patterns, we replace the highest-level binary pattern by a high-order sinusoidal pattern. In our proposed system, a pan-tilt stage carrying a checkerboard is used to assist the simultaneous calibration of the camera and projector. Initially, the camera is calibrated to obtain the extrinsic positions of the stage. In addition, we utilize the multiplication of vertical and horizontal stripe patterns to enhance the corresponding features between the camera and projector. The projector is then calibrated using the extrinsic features determined from the calibrated camera. The experimental results show that the use of the high-order sinusoidal pattern significantly improves reprojection error. Our proposed method can easily be incorporated in the defocusing projector for scanning various types of objects.

A novel method for destriping of OCM-2 data and radiometric performance analysis for improved ocean color data products

Despite the capability of Ocean Color Monitor aboard Oceansat-2 satellite to provide frequent, high-spatial resolution, visible and near-infrared images for scientific research on coastal zones and climate data records over the global ocean, the generation of science quality ocean color products from OCM-2 data has been hampered by serious vertical striping artifacts and poor calibration of detectors. These along-track stripes are the results of variations in the relative response of the individual detectors of the OCM-2 CCD array. The random unsystematic stripes and bandings on the scene edges affect both visual interpretation and radiometric integrity of remotely sensed data, contribute to confusion in the aerosol correction process, and multiply and propagate into higher level ocean color products generated by atmospheric correction and bio-optical algorithms. Despite a number of destriping algorithms reported in the literature, complete removal of stripes without residual effects and signal distortion in both low- and high-level products is still challenging. Here, a new operational algorithm has been developed that employs an inverted gaussian function to estimate error fraction parameters, which are uncorrelated and vary in spatial, spectral and temporal domains. The algorithm is tested on a large number of OCM-2 scenes from Arabian Sea and Bay of Bengal waters contaminated with severe stripes. The destriping effectiveness of this approach is then evaluated by means of various qualitative and quantitative analyses, and by comparison with the results of the previously reported method. Clearly, the present method is more effective in terms of removing the stripe noise while preserving the radiometric integrity of the destriped OCM-2 data. Furthermore, a preliminary time-dependent calibration of the OCM-2 sensor is performed with several match-up in-situ data to evaluate its radiometric performance for ocean color applications. OCM-2 derived water-leaving radiance products obtained after calibration show a good consistency with in-situ and MODIS-Aqua observations, with errors less than the validated uncertainties of ±5% and ±35% endorsed for the remote-sensing measurements of water-leaving radiance and retrieval of chlorophyll concentrations respectively. The calibration results show a declining trend in detector sensitivity of the OCM-2 sensor, with a maximum effect in the shortwave spectrum, which provides evidence of sensor degradation and its profound effect on the striping artifacts in the OCM-2 data products.

Singly periodic free boundary minimal surfaces in a solid cylinder of [formula omitted

The aim of this work is to show there exist free boundary minimal surfaces of Saddle Tower type which are embedded in a vertical solid cylinder of H2×R,H2 being the hyperbolic plane, and invariant under the action of a vertical translation and a rotation. The number of boundary curves equals 2l,l⩾2. These surfaces come in families depending on one parameter and they converge to 2l vertical stripes having a common intersection line.

A sign of mobility and cultural exchange? The ceramics with scribble line ornamentation from Lysa Hora cemetery

the fourth type after D.Y. Telegin typology has been found in the Lysa Gora cemetery. This type is represented by biconical vessels with the flat bottom and straight «collar» rim. Inside of this type, we are able to identify subtypes by their size, type and ornament disposition on the body of a vessel. The vessels with the flat bottom, straight vertical walls and cut to the middle rim are most common. In the second period biconical vessels with the big flat “collar” rim became more popular. The plot of the composition and ornaments that decorated the body of the vessel in the first and second period also was changed. The ornament in the first period is the imprints of the comb punches forming the horizontal rows, the fir-tree, the zigzag, the ribbons, limited by the scratched lines, the comb marks. The ornament in the first period is the imprints of the comb punches forming the horizontal rows, the fir-tree, the zigzag, the ribbons, limited by the scratched lines, the comb marks. In the second period – the ornament of the triangular stroked decoration and the shaded horizontal lines, which form plots: geometric compositions, fir trees, nets, extends. A linear ornament consists of cut, screwed or flattened lines. Often, it is a straight line, in some cases there are curvilinear compositions, sometimes wavy ornament. In different periods of culture, there are certain differences in the motifs of patterns, the ways of their placement, the degree of coverage of the ornament of the surface of vessels. In the first period of culture, the pattern on vessels did not adhere to a clear horizontal zonation. Pots of the second period are ornamented from the rim to bottom. Sometimes the pattern enters the inside of the neck and rim of the vessel, as well as the bottom. The style of geometric rectilinear ornament prevails, which most often includes horizontal rows and stripes. Rows consist of impressions of the comb, the triangular short stroked decoration. Impressions of the comb, the triangular short stroked decoration in individual rows have a slope to the right or to the left, resulting in a pattern having a kind of fir tree. Less often, the ornamental field consisted of several horizontal stripes, separated by the triangular stroked decoration of the necks or flattened lines. The entire strip is covered with lines from the stroked decoration or impressions of the comb. Sometimes the entire strip filled with “broken” rows, which in general creates a motive of short vertical columns. However, curvilinear pattern of ornament did not common for this period. The feature of ceramics is its ornamented bottom. Patterns consist of concentric circles, elongated-oval circles, radial lines. At the end of the second – at the beginning of the third period of the Dnieper-Donetsk culture region a tendency is to create a pattern with a predominance of vertical or oblique columns and stripes, more often there is a pattern of ornament in the form of individual figures (triangles, lozenges, which sparsely cover the surface of the vessel). The development and change of the disposition of ornament on ceramics is one of the keys to understand socio-cultural connections on the territory of the Dnieper-Donetsk cultural region.

<i>Padina pavonica</i>: Morphology and Calcification Functions and Mechanism

Padina pavonica is one of the common macro-algae that inhabit coastal inter-tidal zones around the world. It is one of the two brown algae known to science today that calcifies. It precipitates CaCO3 in the microscopy form of Aragonite needle shape seen macroscopically as a vertical ventral stripes. Here we will summarize the information available since the beginning of the 20th century, taking into consideration the algal distribution, macro and micro-morphology, cytology, reproduction, CaCO3 bio-mineralization, and a slight reference to the commercial aspects, i.e., its use in the medical and cosmetic industries. This paper discusses the likely advantages that Padina gains by the calcification and the effect of pH caused by global climate changes on this calcification. We will describe the distribution of Padina, while focusing on the morphology of P. pavonica, as described in the literature, occasionally comparing it to another common species in Tel-Baruch—P. gymnospora. This review is somewhat prolog for the upcoming research.