Sufficient conditions for topological invariance of 2D images under rigid transformations

International audienceIn ℝ^2, rigid transformations are topology-preserving operations. However, this property is generally no longer true when considering digital images instead of continuous ones, due to digitization effects. In this article, we investigate this issue by studying discrete rigid transformations (DRTs) on ℤ^2. More precisely, we define conditions under which digital images preserve their topological properties under any arbitrary DRTs. Based on the recently introduced notion of DRT graph and the classical notion of simple point, we first identify a family of local patterns that authorize topological invariance under DRTs. These patterns are then involved in a local analysis process that guarantees topological invariance of whole digital images in linear time

Global Retinoblastoma Presentation and Analysis by National Income Level

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4) were female. Most patients (n = 3685 84.7%) were from low-and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 62.8%), followed by strabismus (n = 429 10.2%) and proptosis (n = 309 7.4%). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 95% CI, 12.94-24.80, and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 95% CI, 4.30-7.68). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs. © 2020 American Medical Association. All rights reserved

The regularities of heavy metals and arsenic accumulation in the vegetation of riverside depending on the level of technogenic load

The regularities of heavy metals (Fe, Cu, Zn, Cd, Pb) and arsenic accumulation in various types of aquatic vegetation have been studied, depending on the season and the levels of pollution of the Srepok River (Vietnam). It has been found that the concentrations of Fe, Cu, Zn, As, Cd and Pb in all studied areas of the river in the roots of water hyacinth and common reed were higher than those in the stems. It has been shown that the content of toxicants in plants varied widely, depending on the level of pollution in the adjacent area. The maximum concentrations of Cu, Zn and Pb were noted in the organs of the water hyacinth and reeds in the lands within the industrial areas, and the highest levels of As and Cd were noted up the stream, before the river entrance into the industrial area. The content of Fe in all areas remained stable. The difference in heavy metals’ concentrations in plants close to the banks in the provinces and in the middle of the river in most cases was not statistically significant. © 2018, Pharmainfo Publications. All rights reserved

The regularities of heavy metals and arsenic accumulation in the vegetation of riverside depending on the level of technogenic load

The regularities of heavy metals (Fe, Cu, Zn, Cd, Pb) and arsenic accumulation in various types of aquatic vegetation have been studied, depending on the season and the levels of pollution of the Srepok River (Vietnam). It has been found that the concentrations of Fe, Cu, Zn, As, Cd and Pb in all studied areas of the river in the roots of water hyacinth and common reed were higher than those in the stems. It has been shown that the content of toxicants in plants varied widely, depending on the level of pollution in the adjacent area. The maximum concentrations of Cu, Zn and Pb were noted in the organs of the water hyacinth and reeds in the lands within the industrial areas, and the highest levels of As and Cd were noted up the stream, before the river entrance into the industrial area. The content of Fe in all areas remained stable. The difference in heavy metals’ concentrations in plants close to the banks in the provinces and in the middle of the river in most cases was not statistically significant. © 2018, Pharmainfo Publications. All rights reserved

Analysis of crack spacing in reinforced concrete by a lattice model

A new numerical method is proposed for prediction of crack spacing in reinforced concrete. It is assumed that the deformation pattern of crack spacing consumes the least energy among all kinematically admissible deformations, and the energy minimization approach is applied to predict crack spacing. To simplify the problem, a lattice model is used, in which the cracking process is represented by softening of the concrete bar elements. The crack spacing due to tension and bending is investigated. The results confirm that crack spacing can be predicted by energy minimization. To account for the influence of the bond slip between the concrete and the reinforcing steel, the traditional bond-link element is employed. The influence of the bond slip on the cracking pattern is studied through numerical examples. The results show that without considering bond-slip, the damage near the reinforcement is distributed rather than localized, whereas considering bond-slip, the damage near the reinforcement is localized. The influence of bond slip on crack spacing is significant

Application of Re-estimation in Re-planning of Software Product Releases

Context: Re-planning of product releases is a very dynamic endeavor and new research methods or improvements of existing methods are still required. This paper explores the role of re-estimation in the re-planning process of product releases. Objective: The purpose of this study is to analyze effects of defect and effort re-estimation in the process of release re-planning. In particular, two questions are answered: Question 1: In the absence of re-estimation, does conducting replanning have any advantages over not conducting re-planning? Question 2: In the case of re-planning, does conducting re-estimation have any advantages over not conducting re-estimation? Method: The proposed method H2W-Pred extends the existing H2W re-planning method by accommodating dynamic updates on defect and effort estimates whenever re-planning takes place. Based on the updates, effort for development of new functionality needs to be re-adjusted and balanced against the additional effort necessary to ensure quality early. The proposed approach is illustrated by case examples with simulated data. Results: The simulation results show that conducting re-planning yields better release value in terms of functionality than not conducting re-planning. Furthermore, performing re-estimation when doing re-planning generates a portfolio of solutions that help balance trade-offs between several aspects of release value, e.g., between functionality and quality. Conclusion: If the development of a product release requires balancing between potentially conflictive aspects, such as quality vs. functionality, then re-estimation in the re-planning process is beneficial