Luminance Changes Research Articles

Target localization method of non-cooperative spacecraft on on-orbit service

With the explosion of the number of meteoroid/orbital debris in terrestrial space in recent years, the detection environment of spacecraft becomes more complex. This phenomenon causes most current detection methods based on machine learning intractable to break through the two difficulties of solving scale transformation problem of the targets in image and accelerating detection rate of high-resolution images. To overcome the two challenges, we propose a novel non-cooperative target detection method using the framework of deep convolutional neural network.Firstly, a specific spacecraft simulation dataset using over one thousand images to train and test our detection model is built. The deep separable convolution structure is applied and combined with the residual network module to improve the network’s backbone. To count the different shapes of the spacecrafts in the dataset, a particular prior-box generation method based on K-means cluster algorithm is designed for each detection head with different scales. Finally, a comprehensive loss function is presented considering category confidence, box parameters, as well as box confidence. The experimental results verify that the proposed method has strong robustness against varying degrees of luminance change, and can suppress the interference caused by Gaussian noise and background complexity. The mean accuracy precision of our proposed method reaches 93.28%, and the global loss value is 13.252. The comparative experiment results show that under the same epoch and batchsize, the speed of our method is compressed by about 20% in comparison of YOLOv3, the detection accuracy is increased by about 12%, and the size of the model is reduced by nearly 50%.

Relationship between pharyngeal or esophageal reconstruction and esophageal pressure after swallowing.

High-resolution manometry, which measures esophageal luminal pressure changes after swallowing, could shed more light on food-transport dynamics after pharyngeal/esophageal reconstruction. This prospective cohort study assessed the influence of two head-and-neck and esophageal tumor-resection and reconstruction approaches on esophageal pressure. The cohort consisted of 17 patients who underwent esophageal/pharyngeal resection/reconstruction for cancer and then participated in postoperative high-resolution manometry. Five healthy controls also underwent manometry for comparison. Partial pharyngectomy with patch grafts associated with smooth and continuous esophageal/pharyngeal movement. By contrast, surgery that removed the thoracic esophagus led to complete loss of peristalsis and poor food transport. High-resolution manometry effectively characterized the changes in food-transport dynamics caused by pharyngeal/esophageal resection/reconstruction. These findings suggest that continuous and smooth movement of the pharynx and esophagus is important for swallowing and high resolution manometry could be useful in patients after pharyngeal/esophageal resection/reconstruction.

Scaling Of Visual Tasks Sensations From Human Centric Lighting Point Of View

Light forms view of the environment and can influence the psychoemotional state in it. Human centric lighting was introduced after the receptor responsible for the effect of illumination on the circadian rhythm, that is, the nonvisual effect of light on the human body, was discovered. To form the concept of human centric lighting requires a holistic approach that takes into account both visual tasks and the psychoemotional state of users in this environment. The degree of discomfort may increase if there are glare light sources in the field of view. Insufficient monotonous illumination with sharp changes in luminance or contrast, which can be estimated using the spatialangular distribution of luminance, can also cause discomfort. The article proposes an experimental approach to assess the quality of illumination in laboratory conditions.

Human Face Perception Using Electroencephalography and Magnetoencephalography.

The face has a large amount of information that is useful for humans in social communication. Recently, non-invasive methods have been used to investigate human brain activity related to perception and cognition processes. Electroencephalography (EEG) and magnetoencephalography (MEG) have excellent temporal resolution and reasonably good spatial resolution. Therefore, they are useful to investigate time sequences of human brain activity related to the face perception process. In this review, we introduce our previous EEG and MEG studies of human face perception that demonstrated the following characteristics of face perception processing: (1) Event-related components in the temporal area related to the activity in the inferior temporal (IT) area, corresponding to the fusiform face area (FFA), are evoked approximately 180 msec after the presentation of a face. The activity in the IT area plays an important role in the detection processing of a face, and the contours of a face affect the activity in the IT areas. (2) Event-related components in the temporal area related to the superior temporal sulcus (STS) activity are larger when eyes are averted than when directly looking into the eyes. (3) The direction of features of a face affects the face perception processing in the right hemisphere. On the other hand, the matching of the direction between the contours and features of a face affects the processing in the left hemisphere. (4) Random dots blinking (RDB), which uses temporal changes in patterns of many small dots to present stimuli without a change in luminance during the presentation of a face, is a useful visual stimulus method to investigate the brain activity related to face perception processing in the IT area using EEG and MEG.

AMOLED Pixel Circuit Compensating Luminance Change by Area Stretching and Voltage Drop

스트레처블 디스플레이는 차세대 유연 디스플레이 기술로서 주목받고 있는 프리폼의 구현이 가능한 디스플레이다. 백라이트 유닛을 사용하지 않는 OLED (organic light emitting diode)와 저온 폴리 실리콘에 비해 공정온도가 낮은 a-IGZO (amorphous In-Ga-Zn Oxide) 박막트랜지스터는 스트레처블 디스플레이에 적용하기에 적합하다. 기판이 연신 되어 면적이 증가하면 평균 휘도가 감소하며 전원 라인은 전원입력 단자로부터 화소까지의 배선 거리에 따라 전원 전압 강하가 증가하여 휘도 불균일이 나타난다. 본 연구에서는 연신에 의한 평균 휘도 저하와 전압 강하에 의한 휘도 변화를 동시에 보상할 수 있는 화소 회로를 제안하였다. 제안된 화소 회로의 구동 트랜지스터의 전류는 면적이 10%와 20% 증가할 때 1.87 %와 3.74 % 증가하여 면적 연신에 의한 휘도 저하를 보상 할 수 있으며 전원전압의 2.3 V의 전압 강하에서, 일반적인 화소 회로의 전류는 25.34% 감소한 반면, 제안된 화소 회로의 전류는 9.31 % 감소하여 전원전압의 감소를 보상 할 수 있다.

A prospective study of preoperative neutrophil to lymphocyte ratio, platelet to lymphocyte ratio and sonological findings in predicting severe cholecystitis

Background: The aims and objectives of the study was to assess the utility of neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and ultrasound findings to predict severe cholecystitis and to identify an NLR, PLR cut off value that discriminates between simple and severe cholecystitis.Methods: A prospective observational time bound study was conducted with sample size of 100 patients from December 2019 to January 2021. Severe cholecystitis was defined as cholecystitis complicated by secondary changes like haemorrhage, gangrene, emphysema, abscess, perforation, carcinoma. NLR, PLR values were calculated from absolute neutrophil count and absolute lymphocyte count. All patients underwent ultrasound abdomen by the same radiologist and findings were grouped into three categories, luminal, mural and pericholecystic changes. Intraoperative findings, Histopathological examinations were also taken into account. Data was analysed using Statistical package for social sciences (SPSS) Software Version 22. Receiver operating characteristic curve analysis was employed to identify optimal NLR, PLR cut off values and to predict combined accuracy of NLR, PLR and Ultrasound findings to predict severe cholecystitis.Results: In our study, 23% patients had severe cholecystitis. The mean age of patients was 46 years. 65% were females. Presence of calculi and presence of multiple calculi was higher in patients with severe cholecystitis (p value 0.25) calculated using Chi square test. Ultrasound findings of luminal, mural and pericholecystic changes were also found to be higher in severe cholecystitis (p<0.001). Mann whitney test showed mean NLR, PLR higher in severe cholecystitis. A Cut off NLR of 3.75 had a sensitivity of 100%, specificity of 77.92%. Length of hospital stay in patients with severe cholecystitis was longer.Conclusions: NLR of 3.75 is a cut off value to predict severe cholecystitis and prolonged length of hospital stay. Combined Predictive Accuracy of NLR, PLR, Ultrasound findings was 91%. Ultrasonography is a reliable, specific diagnostic tool.

Delay and Speed of Visual Feedback of a Keystroke Cause Illusory Heaviness and Stiffness.

Imposing a delay between an action (e.g., a limb movement) and its related visual feedback (e.g., a cursor movement on the display) induces a peculiar sensation of heaviness or stiffness. Earlier studies have examined this delay-induced heaviness or stiffness sensation in relation to the non-arbitrary causal relationship between an action and its effect. Here, “non-arbitrary causal relationship” means that an action produces a specific and deterministic pattern of visual feedback; for example, a leftward limb movement consistently and deterministically causes a leftward visual motion. In modern graphical user interfaces, on the other hand, users often control visual information by pressing keys, wherein the relationship between the keystroke and the change in visual information is arbitrary. The present study examined whether the sensation of heaviness, stiffness and bumpiness could be caused when participants' keystroke produced a delayed arbitrary visual feedback. Participants were asked to press and hold down an assigned key to cause temporal luminance changes in a square centered on the display, an arbitrary visual feedback of their keystroke. Not only the onset delay of the temporal luminance change from the participant's keystroke but also the speed of the temporal luminance change were examined as a visual cue to heaviness, stiffness, or bumpiness. In Experiment 1, the participants' task was to give a rating for the strength of the heaviness, stiffness, or bumpiness perceived when they pressed the key. Our results showed that the heaviness and stiffness ratings increased as the delay increased and decreased as the speed increased. To check whether the manipulation of the delay and speed of the visual feedback caused changes in the subjective evaluation of sensorimotor incongruence, in Experiment 2, we asked the participants to give a rating for the sense of agency. The rating scores decreased as the delay increased and increased as the speed increased. The delay and speed influenced the rating scores for the sense of agency in the opposite direction to those for heaviness/stiffness. We discuss that the brain determines the heaviness and stiffness during a keystroke based on internalized statistics relating to the delay and speed of the action feedback.

Neutrophil-Lymphocyte Ratio (NLR), Platelet-Lymphocyte Ratio (PLR) and Sonological Findings in Predicting Severe Cholecystitis

Aims and Objectives: To assess the utility of Neutrophil-Lymphocyte Ratio (NLR), Platelet-Lymphocyte Ratio (PLR) & Ultrasound findings to predict Severe Cholecystitis. To identify an NLR, PLR cut off value to discriminate between simple and severe cholecystitis. METHODS: A prospective observational time bound study conducted with sample size of 100 patients from December 2019 to January 2021. Severe cholecystitis was defined as cholecystitis complicated by secondary changes like haemorrhage, gangrene, emphysema, abscess, perforation, carcinoma. NLR, PLR values were calculated from absolute neutrophil count and absolute lymphocyte count. All patients underwent Ultrasound abdomen by the same Radiologist, findings were grouped into three categories, Luminal, Mural and Pericholecystic changes. Intraoperative findings, Histopathological examinations were also taken into account. Data was analysed using SPSS Software Version 22. Receiver Operating Characteristic Curve analysis was employed to identify optimal NLR, PLR Cut off values and to predict Combined accuracy of NLR, PLR and Ultrasound findings to predict severe cholecystitis. Results: In our study, 23% patients had severe cholecystitis. Mean age was 46 years. 65% were females. Presence of calculi and presence of multiple calculi was higher in patients with severe cholecystitis (p value 0.25) calculated using Chi square test. Ultrasound findings of Luminal, Mural and Pericholecystic changes were also higher in severe cholecystitis (p value <0.001). Mann whitney test showed mean NLR, PLR higher in severe cholecystitis. A Cut off NLR of 3.75 had a sensitivity of 100%, specificity of 77.92%. Length of hospital stay in patients with severe cholecystitis was longer. CONCLUSION: NLR of 3.75 is a cut off value to predict severe cholecystitis and prolonged length of hospital stay. Combined Predictive Accuracy of NLR, PLR, Ultrasound findings was 91%. Ultrasonography is a reliable, specific diagnostic tool.

The phosphoinositide PI(3,5)P2 inhibits the activity of plant NHX proton/potassium antiporters: Advantages of a novel electrophysiological approach

In the present work, we discuss the way in which the parallel application of the patch-clamp technique and the 2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) fluorescence detection for recording luminal proton changes allows the functional characterization of nonelectrogenic potassium/proton vacuolar antiporters of the NHX (Na+/H+ exchanger) family. Moreover, we review the functional role of the tonoplast-specific phosphoinositide PI(3,5)P2, able to simultaneously inhibit the activity of NHXs and CLC-a transporters, whose coordinated action can play an important role in the water balance of plant cells.

An Investigation of the Implications of Visual Impairment for Illumination Requirements

Introduction The present contribution mainly focuses on the evaluation of the visual performance of people with impaired vision and, for comparison purposes, individuals with typical vision under different lighting conditions. Methods: A monitor with adjustable brightness facilitated various test runs to determine the visual performance as a function of the adaptation luminance and glare. In addition, the subjective impressions of the participants with impaired vision were queried via interviews. The study included 98 people with impaired vision and 38 people without visual impairments. Results: The interview results suggest that most people with visual impairments require special lighting conditions. An increased lighting requirement is observed amongst 50% of this group. Moreover, 75% of this group display increased glare sensitivity. Likewise, adaptation problems and critical issues related to nonuniform lighting are manifest. Individuals with impaired vision included in this study display a greatly reduced contrast threshold and a higher subjective level of discomfort compared to individuals with typical vision.Discussion: Most visually impaired participants state that they require a higher degree of brightness to achieve their maximum personal visual performance. However, about a quarter of the participants reported that they achieve a better visual performance at lower brightness, while displaying an increased sensitivity to glare. In general, glare has a decisive influence on the visual performance of the participants with impaired vision in our study. Implications for Practitioners: The study reconfirms the essential importance of glare-free and uniform general lighting strategies (e.g., via predominantly indirect lighting) as well as avoiding abrupt spatiotemporal luminance changes (e.g., via provision of a transition zone between locations with very different luminance levels).

Proteasome-Mediated Regulation of GATA2 Expression and Androgen Receptor Transcription in Benign Prostate Epithelial Cells.

GATA2 has been shown to be an important transcription factor together with androgen receptor (AR) in prostate cancer cells. Less is known about GATA2 in benign prostate epithelial cells. We have investigated if GATA2 exogenous expression in prostate epithelial basal-like cells could induce AR transcription or luminal differentiation. Prostate epithelial basal-like (transit amplifying) cells were transduced with lentiviral vector expressing GATA2. Luminal differentiation markers were assessed by RT-qPCR, Western blot and global gene expression microarrays. We utilized our previously established AR and androgen-dependent fluorescence reporter assay to investigate AR activity at the single-cell level. Exogenous GATA2 protein was rapidly and proteasome-dependently degraded. GATA2 protein expression was rescued by the proteasome inhibitor MG132 and partly by mutating the target site of the E3 ligase FBXW7. Moreover, MG132-mediated proteasome inhibition induced AR mRNA and additional luminal marker gene transcription in the prostate transit amplifying cells. Different types of intrinsic mechanisms restricted GATA2 expression in the transit amplifying cells. The appearance of AR mRNA and additional luminal marker gene expression changes following proteasome inhibition suggests control of essential cofactor(s) of AR mRNA expression and luminal differentiation at this proteolytic level.

Comprehensive Evaluation and Unique Morphologic Features of Nonsteroidal Anti-Inflammatory Drug (NSAID) Enteropathy in the Terminal Ileum.

Differentiating NSAID enteropathy from Crohn disease can be challenging on terminal ileum biopsy. It is important to distinguish these two entities for management. In this study, clinical, radiographic, endoscopic, and histologic features of 30 patients diagnosed with NSAID enteropathy and 30 patients diagnosed with Crohn disease on terminal ileal biopsy were compared. None of the patients in the NSAID cohort demonstrated significant changes on imaging performed prior to biopsy. Depending on disease severity, patients with Crohn disease showed imaging findings ranging from minimal changes to significant bowel wall and/or luminal changes. Endoscopically, erythema, erosions, and/or ulcers in the terminal ileum were observed in a majority of NSAID cases. Patients with active Crohn disease were noted to have erythema, ulcers, strictures, and/or visible inflammation throughout the distal ileum and colon. Histologically, at least 80% of cases in each cohort showed ulceration/erosion and cryptitis/crypt abscesses. The Crohn disease cohort had significantly higher degree of lymphoplasmacytic inflammation in the lamina propria compared to the NSAID cohort. In contrast, a significantly higher percentage of the NSAID cohort had gland/crypt atrophy. A decrease in number of Paneth cells was found in the NSAID cohort. Decreased lamina propria lymphoplasmacytic inflammation was the most specific and the presence of gland atrophy the most sensitive feature favoring NSAID enteropathy. In summary, the combination of gland/crypt/Paneth cell atrophy with decreased lamina propria lymphoplasmacytic inflammation can aid in differentiating NSAID enteropathy from Crohn disease in terminal ileal biopsies; however, correlation with clinical, radiographic, and endoscopic findings is still required.

Input from torus longitudinalis drives binocularity and spatial summation in zebrafish optic tectum

BackgroundA continued effort in neuroscience aims to understand the way brain circuits consisting of diverse neuronal types generate complex behavior following sensory input. A common feature of vertebrate visual systems is that lower-order and higher-order visual areas are reciprocally connected. Feedforward projections confer visual responsiveness to higher-order visual neurons while feedback projections likely serve to modulate responses of lower-order visual neurons in a context-dependent manner. Optic tectum is the largest first-order visual brain area in zebrafish and is reciprocally connected with the torus longitudinalis (TL), a second-order visual brain area that does not receive retinal input. A functional role for feedback projections from TL to tectum has not been identified. Here we aim to understand how this feedback contributes to visual processing.ResultsIn this study, we demonstrate that TL feedback projections to tectum drive binocular integration and spatial summation in a defined tectal circuit. We performed genetically targeted, cell type-specific functional imaging in tectal pyramidal neurons (PyrNs) and their two input neuron populations: retinal ganglion cells (RGCs) and neurons in TL. We find that PyrNs encode gradual changes in scene luminance using a complement of three distinct response classes that encode different light intensity ranges. Functional imaging of RGC inputs to tectum suggest that these response classes originate in the retina and RGC input specifies PyrN functional classes. In contrast, TL input serves to endow PyrNs with large, compound receptive fields that span both retinal hemifields.ConclusionsThese findings reveal a novel role for the zebrafish TL in driving binocular integration and spatial summation in tectal PyrNs. The neural circuit we describe generates a population of tectal neurons with large receptive fields tailored for detecting changes in the visual scene.

Fractal-Based Analysis of fMRI BOLD Signal During Naturalistic Viewing Conditions

Background: Temporal fractals are characterized by prominent scale-invariance and self-similarity across time scales. Monofractal analysis quantifies this scaling behavior in a single parameter, the Hurst exponent (H). Higher H reflects greater correlation in the signal structure, which is taken as being more fractal. Previous fMRI studies have observed lower H during conventional tasks relative to resting state conditions, and shown that H is negatively correlated with task difficulty and novelty. To date, no study has investigated the fractal dynamics of BOLD signal during naturalistic conditions.Methods: We performed fractal analysis on Human Connectome Project 7T fMRI data (n = 72, 41 females, mean age 29.46 ± 3.76 years) to compare H across movie-watching and rest.Results: In contrast to previous work using conventional tasks, we found higher H values for movie relative to rest (mean difference = 0.014; p = 5.279 × 10−7; 95% CI [0.009, 0.019]). H was significantly higher in movie than rest in the visual, somatomotor and dorsal attention networks, but was significantly lower during movie in the frontoparietal and default networks. We found no cross-condition differences in test-retest reliability of H. Finally, we found that H of movie-derived stimulus properties (e.g., luminance changes) were fractal whereas H of head motion estimates were non-fractal.Conclusions: Overall, our findings suggest that movie-watching induces fractal signal dynamics. In line with recent work characterizing connectivity-based brain state dynamics during movie-watching, we speculate that these fractal dynamics reflect the configuring and reconfiguring of brain states that occurs during naturalistic processing, and are markedly different than dynamics observed during conventional tasks.

Endometrial receptivity in cattle: the mutual reprogramming paradigm.

Prior to implantation in cattle, the mucous medium contained in the uterine lumen serves as a working interface for molecular exchange and signaling between the lining endometrium and the embryo. The composition of this luminal fluid changes temporally according to the secretory and reabsorptive activities of the uterus and the embryo, which are under complex regulation. Via this interface, both the embryo and the endometrium reprogram each other's functions to support pregnancy continuation beyond the pre-implantation period. More specifically, the embryo receives elongation signals and the uterus receives anti-luteolytic stimuli. Here, characteristics of the luminal compartment as well as the regulation of its composition to determine the pregnancy outcome will be discussed.

NeuroVis: Real-Time Neural Information Measurement and Visualization of Embodied Neural Systems.

Understanding the real-time dynamical mechanisms of neural systems remains a significant issue, preventing the development of efficient neural technology and user trust. This is because the mechanisms, involving various neural spatial-temporal ingredients [i.e., neural structure (NS), neural dynamics (ND), neural plasticity (NP), and neural memory (NM)], are too complex to interpret and analyze altogether. While advanced tools have been developed using explainable artificial intelligence (XAI), node-link diagram, topography map, and other visualization techniques, they still fail to monitor and visualize all of these neural ingredients online. Accordingly, we propose here for the first time “NeuroVis,” real-time neural spatial-temporal information measurement and visualization, as a method/tool to measure temporal neural activities and their propagation throughout the network. By using this neural information along with the connection strength and plasticity, NeuroVis can visualize the NS, ND, NM, and NP via i) spatial 2D position and connection, ii) temporal color gradient, iii) connection thickness, and iv) temporal luminous intensity and change of connection thickness, respectively. This study presents three use cases of NeuroVis to evaluate its performance: i) function approximation using a modular neural network with recurrent and feedforward topologies together with supervised learning, ii) robot locomotion control and learning using the same modular network with reinforcement learning, and iii) robot locomotion control and adaptation using another larger-scale adaptive modular neural network. The use cases demonstrate how NeuroVis tracks and analyzes all neural ingredients of various (embodied) neural systems in real-time under the robot operating system (ROS) framework. To this end, it will offer the opportunity to better understand embodied dynamic neural information processes, boost efficient neural technology development, and enhance user trust.

Distinct sensory- and goal-related signals underlie the gap effect in the superior colliculus.

The removal of a fixation point (FP) prior to the appearance of a saccade target (gap effect) influences pre-motor circuits and reduces saccadic reaction time (SRT). Saccade preparation signals underlying the gap effect have been observed within the intermediate layers of the superior colliculus (SCi). Neurons in the caudal SCi, coding a target location, increase their activity during the gap, while neurons in the rostral SCi, with tonic activity related to visual fixation, decrease activity. However, the gap effect confounds two factors: (1) a goal-driven temporal warning component (upcoming saccade target appearance) and (2) a stimulus-driven sensory component (FP disappearance). These factors combine to reduce SRT and elicit pre-target responses in the SCi. To dissociate warning and sensory effects, we altered the luminance of the FP during the gap period (renamed warning period) such that it could increase, decrease, or stay the same. Faster SRTs resulted with larger decrements in FP luminance. Different categories of SCi warning period activity were evaluated: (1) always increasing or decreasing or (2) sensory-linked responses to changes in FP luminance. In the caudal SCi (at the location coding the target), all activity correlated negatively with SRT (i.e., saccade facilitation), and two categories of activity were observed (always increasing or opposing FP luminance changes). In the rostral SCi, four categories of activity were observed: activity that increased or followed the change in FP luminance correlated positively with SRT (i.e., saccade inhibition), while activity that decreased or opposed FP luminance changes correlated negatively with SRT. Such SCi activity reflected both goal-driven saccade preparation signals and FP sensory properties.

Analysis of LLL System Properties for Different Excitation Parameters

Photoluminescent strips forming a Low Location Lighting (LLL) system are the primary method for marking escape routes on passenger ships. The LLL system can be built as a self-luminous system (powered by electricity) or made as a series of strips made of photoluminescent materials, which glow and indicate the escape route after the loss of basic and emergency lighting. To ensure correct visual guidance, these strips must be installed at specific locations in the passageways and achieve appropriate photometric parameters after a certain time from their activation. The properties of the LLL system depend on the type of luminescent material used, the excitation source, and the exposure parameters. This paper presents the results of laboratory tests on two types of photoluminescent materials used for the construction of LLL systems. We recorded the change in luminance after the loss of excitation and measured the luminance values obtained 10 and 60 min after the loss of excitation under exposure to light sources commonly used for interior lighting on passenger ships. It turns out that replacing fluorescent lamps with LED lamps can reduce the luminance of the LLL system.

Ultra-Short Term Evaluation of Coronary Vessel Wall Changes in Reference Segments Adjacent to Culprit Lesions in ST-Segment Elevation Myocardial Infarction.

Culprit lesions of ST-segment elevation myocardial infarction (STEMI) patients are friable, soft, and prone to disruption during primary percutaneous coronary intervention (pPCI). The presence of dissections in reference vessel segments (RVSs), adjacent to stented culprit lesions, and dynamic luminal changes in proximal or distal RVSs have not yet been investigated. We therefore sought to assess the healing patterns of edge dissections and the changes of lumen area at RVSs within 1 week post stent implantation in patients with STEMI. In the MATRIX trial (ClinicalTrials.gov NCT01433627), optical coherence tomography (OCT) was performed at the end of pPCI and within 1 week during staged PCI. The RVS dissection was defined as: type 1 = flap; type 2 = cavity; type 3 = double barrel; and type 4 = fissure. We compared separately the fate of residual dissection and luminal area/dimension by OCT in the target vessel between pPCI and staged PCI, including 1-year clinical outcomes. Out of 151 patients, 46 patients had dissections in 50 RVSs and did not experience worse clinical outcome. Dissections were 44% type 1, 28% type 2, 12% type 3, and 16% type 4. Overall, 18% of the dissections healed. The mean lumen area of the RVS enlarged in 82 patients (59%) from pPCI to staged PCI. Compared with the proximal RVS, there was a significant increase in the lumen diameter at the distal RVS (0.06 ± 0.25 mm vs -0.01 ± 0.21 mm; P=.01). Dissections occur frequently after pPCI. One-fifth of them heal within 1 week and do not seem to negatively impact clinical outcomes. Distal RVS lumen area increased compared with proximal RVS, likely reflecting a different vasoconstriction pattern over time.

Luminance texture boundaries and luminance step boundaries are segmented using different mechanisms

In natural scenes, two adjacent surfaces may differ in mean luminance without any sharp change in luminance at their boundary, but rather due to different relative proportions of light and dark regions within each surface. We refer to such boundaries as luminance texture boundaries (LTBs), and in this study we investigate whether LTBs are segmented using different mechanisms than luminance step boundaries (LSBs). We develop a novel method to generate luminance texture boundaries from natural uniform textures, and using these natural LTB stimuli in a boundary segmentation task, we find that observers are much more sensitive to identical luminance differences which are defined by textures (LTBs) than by uniform luminance steps (LSBs), consistent with the possibility of different mechanisms. In a second and third set of experiments, we characterize observer performance segmenting natural LTBs in the presence of masking LSBs which observers are instructed to ignore. We show that there is very little effect of masking LSBs on LTB segmentation performance. Furthermore, any masking effects we find are far less than those observed in a control experiment where both the masker and target are LSBs, and far less than those predicted by a model assuming identical mechanisms. Finally, we perform a fourth set of boundary segmentation experiments using artificial LTB stimuli comprised of differing proportions of white and black dots on opposite sides of the boundary. We find that these stimuli are also highly robust to masking by supra-threshold LSBs, consistent with our results using natural stimuli, and with our earlier studies using similar stimuli. Taken as a whole, these results suggest that the visual system contains mechanisms well suited to detecting surface boundaries that are robust to interference from luminance differences arising from luminance steps like those formed by cast shadows.