Contour Processing Research Articles

Head and neck multi-organ auto-segmentation on CT images aided by synthetic MRI.

Because the manual contouring process is labor-intensive and time-consuming, segmentation of organs-at-risk (OARs) is a weak link in radiotherapy treatment planning process. Our goal was to develop a synthetic MR (sMR)-aided dual pyramid network (DPN) for rapid and accurate head and neck multi-organ segmentation in order to expedite the treatment planning process. Forty-five patients' CT, MR, and manual contours pairs were included as our training dataset. Nineteen OARs were target organs to be segmented. The proposed sMR-aided DPN method featured a deep attention strategy to effectively segment multiple organs. The performance of sMR-aided DPN method was evaluated using five metrics, including Dice similarity coefficient (DSC), Hausdorff distance 95% (HD95), mean surface distance (MSD), residual mean square distance (RMSD), and volume difference. Our method was further validated using the 2015 head and neck challenge data. The contours generated by the proposed method closely resemble the ground truth manual contours, as evidenced by encouraging quantitative results in terms of DSC using the 2015 head and neck challenge data. Mean DSC values of 0.91±0.02, 0.73±0.11, 0.96±0.01, 0.78±0.09/0.78±0.11, 0.88±0.04/0.88±0.06 and 0.86±0.08/0.85±0.1 were achieved for brain stem, chiasm, mandible, left/right optic nerve, left/right parotid, and left/right submandibular, respectively. We demonstrated the feasibility of sMR-aided DPN for head and neck multi-organ delineation on CT images. Our method has shown superiority over the other methods on the 2015 head and neck challenge data results. The proposed method could significantly expedite the treatment planning process by rapidly segmenting multiple OARs.

Study of features of differentiated soil treatment by machine-tractor units on agricultural landscapes of slope lands

The paper considers the features of anti-erosion contour tillage on slope lands, taking into account the location of technological furrows at an angle to the horizontal of the slope. Obtaining information about the terrain model is possible in different ways, including before processing and during the processing of the soil on the slope by a machine-tractor unit. In this case, it is necessary to calculate the angle of deviation of the soil treatment direction relative to the slope when pro-cessing the correct areas with such machines on a complex slope. It has been established that when technological furrows are placed in a straight line, the erosion process develops significantly, for example, when using passive working bodies of agricultural machines (tooth harrows, coverers) on slope lands. For processing complex slope lands, we propose to use the active harrow as an anti-erosion tool in a machine-tractor unit. We have obtained a mathematical model for processing complex slope lands with an active harrow as part of a machine-tractor unit. The proposed approach can be used on slope lands with a slope of up to 15 degrees. Thus, the prerequisites for contour processing of soil on slopes by forming technological furrows with a zero slope are justified, which excludes additional agrotechnical and hydrotechnical anti-erosion and reclamation measures on slope lands with a slope of up to 15 degrees.

Neural responses to dynamic adaptation reveal the dissociation between the processing of the shape of contours and textures

Shape-adaptation studies show that surround textures can inhibit the processing of contours. Using event-related potentials (ERP), we examined the time-course of neural processes involved in contour-shape and texture-shape processing following adaptation to contours and textures. Contours were made of Gabor strings whose orientations were either tangential or orthogonal to the contour path, while textures were made of a series of contours arranged in parallel. We focused on two ERP components –P1, related to low-level visual processes and N1, broadly indicative of mid-level vision– and, on ERP difference waves (no-adaptor minus with-adaptor) to isolate the effects of adaptation, which are fundamentally distinct from individual processes driving P1 and N1 components. We found that in the absence of adaptation, the N1 component for contour-tests peaked later and increased in amplitude compared to the N1 for texture-tests. Following adaptation, the ERP difference wave for contour-tests revealed an early and a late component that were differentially affected by the presence of surround texture, but critically not by its orientation. For texture-tests, the early component was of opposite polarity for contours compared to texture adaptors. From the temporal sequence of ERP modulations, we conclude that texture processing begins before contour processing and encompasses the stages of perceptual processing reflected in both the low-level P1 and the mid-level N1 vision-related components. Our study provides novel evidence on the nature of separable and temporally distinct texture and contour processing mechanisms, shown in two difference wave components, that highlights the multi-faceted nature of dynamic adaptation to shape when presented in isolation and in context.

A textual framework for contour retrieval using sub-multiple contour striking spread position learning

In edge-based retrieval systems, a learning model to contour processing is required to enhance the retrieval process. This paper presents a textual view of contour retrieval problem by feature similarity learning (FSL). The proposed model detects the number of contours in the image to process in an image spread area of interest that strikes its local directions of trajectories and lines of map levels by preserving its feature characteristics by FSL. Experiments on database images is learning with several query image, show that the proposed model can provide better results. They have illustrated the performance of the proposed learning model in various numerical experiments.

ВИЗНАЧЕННЯ ДИНАМІЧНИХ ХАРАКТЕРИСТИК ВИКОНАВЧИХ ОРГАНІВ ТЕХНОЛОГІЧНОГО ОБЛАДНАННЯ

The production of complicated profile parts for aerospace technology is carried out by processing along spatial paths. The nature of the movement of each axis of the equipment is dynamic and unsteady-state. Accuracy must be ensured not only in a steady-state but also in dynamic mode. The determination of dynamic characteristics of the executive bodies is an important and urgent task to optimize the control process. An experimental research method using capabilities of the CNC system, which was equipped with additional hardware and software, is proposed. This allows to register a large number of parameters that describe the state of the equipment, the solving of the task of trajectory interpolating, the formation of control actions, the actual movement of the executive bodies. The methods of conducting experimental studies with the setting of a stepwise change in speed and with a change in speed according to the harmonic law for an open-loop and closed-loop system using various components of the feedforward in the regulator are considered. The use of circular interpolation for the formation of a harmonic law of speed change is proposed. The results of the study of the dynamic of the transition process of an open system are shown. The frequency characteristics of the drive under study are obtained. Its bandwidth is determined. The study of the moving process when the axis velocity changes in harmonic law was performed within the passband. The possibility of determining the maximum permissible values of inertial loads by the nature of the change in actual acceleration is shown. The influence of the regulator feedforward composition on the accuracy of positioning of the servo drive and the accuracy of the contour processing at various frequencies of the control action is studied. For each feedforward method, the frequency ranges of the control action are determined, on which the specified processing accuracy is ensured. It was found that the technological frequency limitation by the accuracy of the reproduction of the path turned out to be significantly more stringent compared to the classical approach for determining the bandwidth.

Brainstem encoding of frequency-modulated sweeps is relevant to Mandarin concurrent-vowels identification for normal-hearing and hearing-impaired listeners

F0 contours convey the primary information of lexical Tones for Mandarin Chinese, and the processing of time-varying F0 contours is important for Mandarin concurrent-vowels identification (MCVI). In this work, we examined the relationship between frequency modulation (FM) detection of auditory system and MCVI in both normal-hearing (NH) and hearing-impaired (HI) listeners. Three experiments were conducted with the same subjects to measure their MCVI, FM detection limen (FMDL), and frequency following responses (FFRs) evoked by FM sweeps, respectively. To ensure that F0 contour was the primary cue utilized, mean F0s and durations were equalized among all test vowels in the MCVI experiment. To simulate the pattern of F0 contours of Mandarin vowels, linearly FM sweeps were used as stimuli in the FMDL and FFRs experiments. The results confirmed that the performance of HI listeners was significantly worse than that of NH listeners in all of the three measurements. Besides, FFRs evoked by FM sweeps had significantly lower tracking accuracy than those evoked by steady tones only for HI listeners. The correlation analysis further revealed that any two of the three measured indices were significantly correlated when the effects of age and absolute threshold were partialed out (|r| ≥ 0.502, p ≤ 0.017). These results suggested an association between the poor performance of HI listeners in the MCVI task and their degraded auditory function on FM detection, and such a behavioral degradation has emerged in the phase-locking activity at the brainstem level.

The effect of primary processing parameters on surface roughness in laser powder bed additive manufacturing

Metal additive manufacturing (AM) is a method to create complex components in a layer-by-layer process. Laser powder bed fusion (LPBF) provides the ability to fabricate complex designs. Components with internal geometries have surfaces that are difficult to improve through post-processing and have been shown to be detrimental to mechanical performance. This work investigates the relationship between primary processing parameters, and surface roughness of nickel-based superalloy 718 fabricated on a LPBF AM machine. The surface roughness of components built using varied contour processing parameters was characterized using both nondestructive and destructive measurement techniques. Statistical correlations are presented between contour processing parameters and surface roughness height metrics along with general trends in the relationships. Results show that the destructive measurements are required to expose notch-like features that are obstructed by powder particles attached to the surface. However, nondestructive methods more easily provide a statistically significant sample size. Understanding the surface roughness can be used for further process optimization and to inform the qualification strategy for AM components.

Femtosecond laser-contoured micro-strain gages

A new concept for foil based micro strain gages (μSG) with sensor elements smaller than 1 mm2 and made possible by a laser contouring process will be presented. In contrast to photolithographic structuring, strain gages structured by laser ablation can be precisely tailored at their measuring destination after the strain sensor blank has been applied. Sensors for measuring very spatially confined elongations in particular, require a precisely positioned and small grid. Accurate mechanical positioning of the measuring grid at the micrometer scale can be challenging due to the much larger, bulky, foil substrate. In cases where a blank is positioned prior to grid patterning by laser ablation, it is even possible to write the measuring grid on smoothly curved, three-dimensional surfaces. A “contour cutting” method is used to minimize grid dimensions and reduce laser processing time, which enables the realization of micrometer-sized grids in a fast, flexible and maskless process. This will extend the range of possible applications for this sensor type (e.g. to include use in very confined spaces). This paper will present the development of a suitable process for the gentle, selective ablation of nickel‑chromium on polyimide substrates by means of ultrashort-pulse lasers. The best results were achieved at a laser fluence of ϕ= 0,43 J/cm2 and a scan speed of 2000 mm/s. Furthermore, the thermal stability of the sensor layer will be investigated and sensors will be characterized in bending tests.

The influence of additive manufacturing processing parameters on surface roughness and fatigue life

Additive manufacturing (AM) is used to create metal components with complex geometries where the internal surfaces cannot easily be post machined. Fatigue behavior in additively manufactured metals is largely driven by defects in the material such as porosity and surface roughness. This work investigates the processing-structure-property-performance (PSPP) relationship for varied contour processing parameters, and the resulting surface roughness features for alloy 718 fabricated using the laser powder bed fusion AM process. Two nondestructive characterization methods are used to determine the relationships between contour parameters and surface roughness characteristics. The benefits of each characterization technique and metrics required for an accurate representation of the additively manufactured surfaces are discussed. Axial fatigue testing is performed to connect the entire PSPP relationship. An understanding of the PSPP relationship with respect to surface roughness features and fatigue life can be used to guide future process parameter optimization and to inform the qualification strategy for AM components.

The real-time dynamics of child-directed speech: Using pupillometry to evaluate children’s processing of natural pitch contours

Young children prefer child-directed speech (CDS) to adult-directed speech (ADS) (Cooper and Aslin 1990), and its structural and prosodic features are known to facilitate learning (Thiessen et al., 2005; Graf Estes and Hurley, 2013). However, little is known about how the real-time dynamics of CDS prosody affect young children’s engagement and learning. In Experiment 1, we evaluated moment-to-moment processing of pitch variation using measures of pupil size synchrony across children (Kang and Wheatley, 2017). 24-to-30-month-old children listened to a story in CDS and ADS, and we found that pupil synchrony was higher for CDS than ADS. Next, using hierarchical clustering, we uncovered 4 main word-level pitch contours from a natural CDS corpus and identified contours (specifically, U- and inverted-U-shaped contours), which elicited lower vs. higher synchrony, respectively. In Experiment 2, we found that children learned novel words better when they were presented in higher- vs. lower-synchrony contours. Importantly, synchrony for a novel word during training significantly predicted learning for the same word at test. By revealing a physiological response that is sensitive to the real-time dynamics of prosody, this investigation yields a new subsecond framework for understanding children’s engagement with a signal known to support early language learning.

Height and contour processes of Crump-Mode-Jagers forests (II): the Bellman–Harris universality class

Crump-Mode-Jagers (CMJ) trees generalize Galton-Watson trees by allowing individuals to live for an arbitrary duration and give birth at arbitrary times during their life-time. In this paper, we exhibit a simple condition under which the height and contour processes of CMJ forests belong to the universality class of Bellman-Harris processes. This condition formalizes an asymptotic independence between the chronological and genealogical structures. We show that it is satisfied by a large class of CMJ processes and in particular, quite surprisingly, by CMJ processes with a finite variance offspring distribution. Along the way, we prove a general tightness result.

Early sensitivity of evoked potentials to surface and volumetric structure during the visual perception of three-dimensional object shape.

This study used event-related potentials (ERPs) to elucidate how the human visual system processes three-dimensional (3-D) object shape structure. In particular, we examined whether the perceptual mechanisms that support the analysis of 3-D shape are differentially sensitive to higher order surface and volumetric part structure. Observers performed a whole-part novel object matching task in which part stimuli comprised sub-regions of closed edge contour, surfaces or volumetric parts. Behavioural response latency data showed an advantage in matching surfaces and volumetric parts to whole objects over contours, but no difference between surfaces and volumes. ERPs were analysed using a convergence of approaches based on stimulus dependent amplitude modulations of evoked potentials, topographic segmentation, and spatial frequency oscillations. The results showed early differential perceptual processing of contours, surfaces, and volumetric part stimuli. This was first reliably observed over occipitoparietal electrodes during the N1 (140-200ms) with a mean peak latency of 170ms, and continued on subsequent P2 (220-260ms) and N2 (260-320ms) components. The differential sensitivity in perceptual processing during the N1 was accompanied by distinct microstate patterns that distinguished among contours, surfaces and volumes, and predominant theta band activity around 4-7Hz over right occipitoparietal and orbitofrontal sites. These results provide the first evidence of early differential perceptual processing of higher order surface and volumetric shape structure within the first 200ms of stimulus processing. The findings challenge theoretical models of object recognition that do not attribute functional significance to surface and volumetric object structure during visual perception.

Influence of Spatial Frequency on Illusory Contour Processing - Early Electrophysiological Indices within the Frontal and Occipital Regions -

Influence of Spatial Frequency on Illusory Contour Processing - Early Electrophysiological Indices within the Frontal and Occipital Regions -

Surface filling-in and contour interpolation contribute independently to Kanizsa figure formation.

To explore mechanisms of object integration, the present experiments examined how completion of illusory contours and surfaces modulates the sensitivity of localizing a target probe. Observers had to judge whether a briefly presented dot probe was located inside or outside the region demarcated by inducer elements that grouped to form variants of an illusory, Kanizsa-type figure. From the resulting psychometric functions, we determined observers' discrimination thresholds as a sensitivity measure. Experiment 1 showed that sensitivity was systematically modulated by the amount of surface and contour completion afforded by a given configuration. Experiments 2 and 3 presented stimulus variants that induced an (occluded) object without clearly defined bounding contours, which gave rise to a relative sensitivity increase for surface variations on their own. Experiments 4 and 5 were performed to rule out that these performance modulations were simply attributable to variable distances between critical local inducers or to costs in processing an interrupted contour. Collectively, the findings provide evidence for a dissociation between surface and contour processing, supporting a model of object integration in which completion is instantiated by feedforward processing that independently renders surface filling-in and contour interpolation and a feedback loop that integrates these outputs into a complete whole. (PsycINFO Database Record

Tunes and Tones: Music, Language, and Inhibitory Control

Abstract A debate is underway regarding the perceptual and cognitive benefits of bilingualism and musical experience. This study contributes to the debate by investigating auditory inhibitory control in English-speaking monolingual musicians, non-musicians, tone language bilinguals, and non-tone language bilinguals. We predicted that musicians and tone language bilinguals would demonstrate enhanced processing relative to monolinguals and other bilinguals. Groups of monolinguals (N = 22), monolingual musicians (N = 19), non-tone language bilinguals (N = 20) and tone language bilinguals (N = 18) were compared on auditory Stroop tasks to assess domain-transferable processing benefits (e.g. auditory inhibitory control) resulting from potentially shared underlying cognitive mechanisms (Patel, 2003; Bialystok & DePape, 2009). In one task, participants heard the words “high” and “low” presented in high or low pitches, and responded regarding the pitch of the stimuli as quickly as possible. In another task, participants heard the words “rise” or “fall” presented in rising or falling pitch contours, and responded regarding the contour of the stimuli as quickly as possible. Results suggest transferable auditory inhibitory control benefits for musicians across pitch and contour processing, but any possible enhanced processing for speakers of tone languages may be task-dependent, as lexical tone activation may interfere with pitch contour processing.

On the age of a randomly picked individual in a linear birth-and-death process

Abstract We consider the distribution of the age of an individual picked uniformly at random at some fixed time in a linear birth-and-death process. By exploiting a bijection between the birth-and-death tree and a contour process, we derive the cumulative distribution function for this distribution. In the critical and supercritical cases, we also give rates for the convergence in terms of the total variation and other metrics towards the appropriate exponential distribution.

International investing in uncertain financial market

International investing is the strategy of selecting globally based investment instruments as a part of an investment portfolio. In order to diversify the portfolios and enhance growth opportunities, more and more firms choose to invest on foreign stocks and derivatives that bring not only stock price risk, but also the exchange rate risk. This paper considers foreign derivatives in an uncertain financial market. Under the assumption that both the exchange rate and the stock price follow uncertain differential equations, the domestic prices of foreign European options, American options and Asian options are developed by means of contour process, respectively. Some examples are finally provided to further demonstrate the properties of the pricing formulas.

Height and contour processes of Crump-Mode-Jagers forests (I): general distribution and scaling limits in the case of short edges

Crump–Mode–Jagers (CMJ) trees generalize Galton–Watson trees by allowing individuals to live for an arbitrary duration and give birth at arbitrary times during their life-time. In this paper, we are interested in the height and contour processes encoding a general CMJ tree. We show that the one-dimensional distribution of the height process can be expressed in terms of a random transformation of the ladder height process associated with the underlying Lukasiewicz path. As an application of this result, when edges of the tree are “short” we show that, asymptotically, (1) the height process is obtained by stretching by a constant factor the height process of the associated genealogical Galton–Watson tree, (2) the contour process is obtained from the height process by a constant time change and (3) the CMJ trees converge in the sense of finite-dimensional distributions.

Visual processing deficits in 22q11.2 Deletion Syndrome.

Carriers of the rare 22q11.2 microdeletion present with a high percentage of positive and negative symptoms and a high genetic risk for schizophrenia. Visual processing impairments have been characterized in schizophrenia, but less so in 22q11.2 Deletion Syndrome (DS). Here, we focus on visual processing using high-density EEG and source imaging in 22q11.2DS participants (N = 25) and healthy controls (N = 26) with an illusory contour discrimination task.Significant differences between groups emerged at early and late stages of visual processing. In 22q11.2DS, we first observed reduced amplitudes over occipital channels and reduced source activations within dorsal and ventral visual stream areas during the P1 (100–125 ms) and within ventral visual cortex during the N1 (150–170 ms) visual evoked components. During a later window implicated in visual completion (240–285 ms), we observed an increase in global amplitudes in 22q11.2DS. The increased surface amplitudes for illusory contours at this window were inversely correlated with positive subscales of prodromal symptoms in 22q11.2DS.The reduced activity of ventral and dorsal visual areas during early stages points to an impairment in visual processing seen both in schizophrenia and 22q11.2DS. During intervals related to perceptual closure, the inverse correlation of high amplitudes with positive symptoms suggests that participants with 22q11.2DS who show an increased brain response to illusory contours during the relevant window for contour processing have less psychotic symptoms and might thus be at a reduced prodromal risk for schizophrenia.

Synergistic Processing of Visual Contours across Cortical Layers in V1 and V2

Visual cortical areas are interconnected via layer-specific feedforward and feedback projections. Such intricate connections are thought to be essential for parsing complex visual images, but the synergy among different layers in different cortical areas remains unclear. By simultaneously mapping neuronal activities across cortical depths in V1 and V2 of behaving monkeys, we identified spatiotemporally dissociable processes for grouping contour fragments and segregating background components. These processes generated and amplified contour signals within specific layers in V1 and V2. Contour-related inter-areal interactions, measured as Granger causality, were also dominant between these cortical layers within a time window when the contour signals were rapidly augmented. The grouping process became much faster for isolated contour elements compared with visual contours embedded in a complex background. Our results delineate the mode whereby image components are grouped and segmented through synergistic inter-laminar and inter-areal processes that are dynamically adjusted during interpretation of sensory inputs.