Persistent Object Search and Surveillance Control With Safety Certificates for Drone Networks Based on Control Barrier Functions
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ABSTRACT:
SUBMITTER: Dan H
PROVIDER: S-EPMC8573941 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Persistent homology provides a new approach for the topological simplification of big data via measuring the life time of intrinsic topological features in a filtration process and has found its success in scientific and engineering applications. However, such a success is essentially limited to qualitative data classification and analysis. Indeed, persistent homology has rarely been employed for quantitative modeling and prediction. Additionally, the present persistent homology is a passive tool, rather than a proactive technique, for classification and analysis. In this work, we outline a general protocol to construct object-oriented persistent homology methods. By means of differential geometry theory of surfaces, we construct an objective functional, namely, a surface free energy defined on the data of interest. The minimization of the objective functional leads to a Laplace-Beltrami operator which generates a multiscale representation of the initial data and offers an objective oriented filtration process. The resulting differential geometry based object-oriented persistent homology is able to preserve desirable geometric features in the evolutionary filtration and enhances the corresponding topological persistence. The cubical complex based homology algorithm is employed in the present work to be compatible with the Cartesian representation of the Laplace-Beltrami flow. The proposed Laplace-Beltrami flow based persistent homology method is extensively validated. The consistence between Laplace-Beltrami flow based filtration and Euclidean distance based filtration is confirmed on the Vietoris-Rips complex for a large amount of numerical tests. The convergence and reliability of the present Laplace-Beltrami flow based cubical complex filtration approach are analyzed over various spatial and temporal mesh sizes. The Laplace-Beltrami flow based persistent homology approach is utilized to study the intrinsic topology of proteins and fullerene molecules. Based on a quantitative model which correlates the topological persistence of fullerene central cavity with the total curvature energy of the fullerene structure, the proposed method is used for the prediction of fullerene isomer stability. The efficiency and robustness of the present method are verified by more than 500 fullerene molecules. It is shown that the proposed persistent homology based quantitative model offers good predictions of total curvature energies for ten types of fullerene isomers. The present work offers the first example to design object-oriented persistent homology to enhance or preserve desirable features in the original data during the filtration process and then automatically detect or extract the corresponding topological traits from the data.
| S-EPMC4685963 | biostudies-literature
Project description:On 10 April 2015, a Dutch TV crew was filming at the Royal Burgers Zoo in Arnhem, The Netherlands. It was the intention to film the chimpanzees in the enclosure from close-by and from above with the means of a drone. When the drone came a bit closer to the chimpanzees, a female individual made two sweeps with a branch that she held in one hand. The second one was successful and downed the drone. The use of the stick in this context was a unique action. It seemed deliberate given the decision to collect it and carry it to a place where the drone might be attacked. This episode adds to the indications that chimpanzees engage in forward planning of tool-use acts.
| S-EPMC4580717 | biostudies-literature
Project description:We perceive objects as containing a variety of attributes: local features, relations between features, internal details, and global properties. But we know little about how they combine. Here, we report a remarkably simple additive rule that governs how these diverse object attributes combine in vision. The perceived dissimilarity between two objects was accurately explained as a sum of (a) spatially tuned local contour-matching processes modulated by part decomposition; (b) differences in internal details, such as texture; (c) differences in emergent attributes, such as symmetry; and (d) differences in global properties, such as orientation or overall configuration of parts. Our results elucidate an enduring question in object vision by showing that the whole object is not a sum of its parts but a sum of its many attributes.
| S-EPMC4790416 | biostudies-literature
Project description:BackgroundThe UK Medical Certificate of Stillbirth (MCS) records information relevant to the cause of stillbirth of infants ≥24 weeks' gestation. A cross-sectional audit demonstrated widespread inaccuracies in MCS completion in 2009 in North West England. A repeat study was conducted to assess whether practice had improved following introduction of a regional care pathway.Methods266 MCS issued in 14 North West England obstetric units during 2015 were studied retrospectively. Cause of death was assigned following review of information available at the time of MCS completion. This was compared to that documented on the MCS, and to data from 2009.ResultsTwenty-three certificates were excluded (20 inadequate data, 3 late miscarriages). 118/243 (49%) MCS contained major errors. Agreement between the MCS and adjudicated cause of stillbirth was fair (Kappa 0.31; 95% CI 0.24, 0.38) and unchanged from 2009 (0.29). In 2015, excluding 34 terminations of pregnancy, the proportion of MCSs documenting "unexplained" stillbirths (113/211; 54%) was reduced compared to 2009 (158/213; 74%); causality could be assigned after case note review in 78% cases. Recognition of fetal growth restriction (FGR) as a cause of stillbirth improved (2015: 30/211; 14% vs 2009: 1/213; 0.5%), although 71% cases were missed. 47% MCSs following termination of pregnancy documented an iatrogenic primary cause of death.ConclusionsCompletion of MCSs remains inaccurate, particularly in recognition of FGR as a cause of stillbirth. Detailed case note review before issuing the MCS could dramatically improve the usefulness of included information; evaluation of practitioner education programmes/internal feedback systems are recommended.
| S-EPMC6221058 | biostudies-literature
Project description:IntroductionVital status is of central importance to hospital clinical research. However, hospital information systems record only in-hospital death information. Recently, the French government released a publicly available dataset containing death-certificate data for over 25 million individuals. The objective of this study was to link French death certificates to the Bordeaux University Hospital records to complete the vital status information.Materials and methodsOur linkage strategy was composed of a search engine to reduce the number of comparisons and machine-learning algorithms. The overall pipeline was evaluated by assembling a file containing 3,565 in-hospital deaths and 15,000 alive persons.ResultsThe recall and precision of our linkage strategy were 97.5% and 99.97% for the upper threshold and 99.4% and 98.9% for the lower threshold, respectively.ConclusionIn this study, we demonstrated the feasibility of accurately linking hospital records with death certificates using a search engine and machine learning.
| S-EPMC7935495 | biostudies-literature
Project description:BACKGROUND:We present a series of experiments on visual search in a highly complex environment, security closed-circuit television (CCTV). Using real surveillance footage from a large city transport hub, we ask viewers to search for target individuals. Search targets are presented in a number of ways, using naturally occurring images including their passports and photo ID, social media and custody images/videos. Our aim is to establish general principles for search efficiency within this realistic context. RESULTS:Across four studies we find that providing multiple photos of the search target consistently improves performance. Three different photos of the target, taken at different times, give substantial performance improvements by comparison to a single target. By contrast, providing targets in moving videos or with biographical context does not lead to improvements in search accuracy. CONCLUSIONS:We discuss the multiple-image advantage in relation to a growing understanding of the importance of within-person variability in face recognition.
| S-EPMC6757089 | biostudies-literature
Project description:Humans and many other species sense visual information with varying spatial resolution across the visual field (foveated vision) and deploy eye movements to actively sample regions of interests in scenes. The advantage of such varying resolution architecture is a reduced computational, hence metabolic cost. But what are the performance costs of such processing strategy relative to a scheme that processes the visual field at high spatial resolution? Here we first focus on visual search and combine object detectors from computer vision with a recent model of peripheral pooling regions found at the V1 layer of the human visual system. We develop a foveated object detector that processes the entire scene with varying resolution, uses retino-specific object detection classifiers to guide eye movements, aligns its fovea with regions of interest in the input image and integrates observations across multiple fixations. We compared the foveated object detector against a non-foveated version of the same object detector which processes the entire image at homogeneous high spatial resolution. We evaluated the accuracy of the foveated and non-foveated object detectors identifying 20 different objects classes in scenes from a standard computer vision data set (the PASCAL VOC 2007 dataset). We show that the foveated object detector can approximate the performance of the object detector with homogeneous high spatial resolution processing while bringing significant computational cost savings. Additionally, we assessed the impact of foveation on the computation of bottom-up saliency. An implementation of a simple foveated bottom-up saliency model with eye movements showed agreement in the selection of top salient regions of scenes with those selected by a non-foveated high resolution saliency model. Together, our results might help explain the evolution of foveated visual systems with eye movements as a solution that preserves perceptual performance in visual search while resulting in computational and metabolic savings to the brain.
| S-EPMC5669499 | biostudies-literature
Project description:Real-world events do not only provide temporally and spatially correlated information across the senses, but also semantic correspondences about object identity. Prior research has shown that object sounds can enhance detection, identification, and search performance of semantically consistent visual targets. However, these effects are always demonstrated in simple and stereotyped displays that lack ecological validity. In order to address identity-based cross-modal relationships in real-world scenarios, we designed a visual search task using complex, dynamic scenes. Participants searched for objects in video clips recorded from real-life scenes. Auditory cues, embedded in the background sounds, could be target-consistent, distracter-consistent, neutral, or just absent. We found that, in these naturalistic scenes, characteristic sounds improve visual search for task-relevant objects but fail to increase the salience of irrelevant distracters. Our findings generalize previous results on object-based cross-modal interactions with simple stimuli and shed light upon how audio-visual semantically congruent relationships play out in real-life contexts.
| S-EPMC6848886 | biostudies-literature
Project description:BackgroundClinical information systems frequently use intranet and Internet technologies. However these technologies have emphasized sharing and not security, despite the sensitive and private nature of much health information. Digital certificates (electronic documents which recognize an entity or its attributes) can be used to control access in clinical intranet applications.ObjectivesTo outline the need for access control in distributed clinical database systems, to describe the use of digital certificates and security policies, and to propose the architecture for a system using digital certificates, cryptography and security policy to control access to clinical intranet applications.MethodsWe have previously developed a security policy, DIMEDAC (Distributed Medical Database Access Control), which is compatible with emerging public key and privilege management infrastructure. In our implementation approach we propose the use of digital certificates, to be used in conjunction with DIMEDAC.ResultsOur proposed access control system consists of two phases: the ways users gain their security credentials; and how these credentials are used to access medical data. Three types of digital certificates are used: identity certificates for authentication; attribute certificates for authorization; and access-rule certificates for propagation of access control policy. Once a user is identified and authenticated, subsequent access decisions are based on a combination of identity and attribute certificates, with access-rule certificates providing the policy framework.ConclusionsAccess control in clinical intranet applications can be successfully and securely managed through the use of digital certificates and the DIMEDAC security policy.
| S-EPMC1761880 | biostudies-literature
Project description:The attentional prioritization hypothesis of object-based attention (Shomstein & Yantis in Perception & Psychophysics, 64, 41-51, 2002) suggests a two-stage selection process comprising an automatic spatial gradient and flexible strategic (prioritization) selection. The combined attentional priorities of these two stages of object-based selection determine the order in which participants will search the display for the presence of a target. The strategic process has often been likened to a prioritized visual search. By modifying the double-rectangle cueing paradigm (Egly, Driver, & Rafal in Journal of Experimental Psychology: General, 123, 161-177, 1994) and placing it in the context of a larger-scale visual search, we examined how the prioritization search is affected by search efficiency. By probing both targets located on the cued object and targets external to the cued object, we found that the attentional priority surrounding a selected object is strongly modulated by search mode. However, the ordering of the prioritization search is unaffected by search mode. The data also provide evidence that standard spatial visual search and object-based prioritization search may rely on distinct mechanisms. These results provide insight into the interactions between the mode of visual search and object-based selection, and help define the modulatory consequences of search efficiency for object-based attention.
| S-EPMC5728374 | biostudies-literature