Camouflage Strategies Research Articles

Multispectral pattern camouflage materials based on PU/Al-flake composite: A CNN-based evaluation

With the continuous progress in optical sensor technologies, the emergence of imagery detection systems operating in the infrared (IR) band has become a reality. In response, we present a novel approach designed to deceive imagery IR detectors targeting fighter jets. To implement this method, we developed a specialized coating technique using a Polyurethane (PU)/Aluminum (Al)-flake composite. This composite coating enables the precise application of IR camouflage patterns while preserving the existing visible camouflages on aircraft surfaces. We customized fighter jet IR image datasets by integrating flow and heat transfer numerical analysis results with real-world background measurements. We then employed the YOLOv3 algorithm, based on a convolutional neural network (CNN), which is known for its high performance in object detection. Through this approach, we analyzed the effects of various pattern shapes on camouflage performance. The proposed PU/Al-flake composite coating offers a versatile and effective solution for overlapping IR camouflage patterns onto existing visible camouflages, providing enhanced protection against advanced IR imagery detection systems. This study highlights the potential of a comprehensive approach to developing and evaluating multispectral camouflage materials and effective camouflage strategies, emphasizing practical applications and real-world performance against IR image detectors.

Revealing a new possible camouflage strategy: use of fungal spores in the 'trash package' of Chrysopidae larvae

Revealing a new possible camouflage strategy: use of fungal spores in the 'trash package' of Chrysopidae larvae

Neural responses to camouflage targets with different exposure signs based on EEG

This study investigates the relationship between various target exposure signs and brain activation patterns by analyzing the EEG signals of 35 subjects observing four types of targets: well-camouflaged, with large color differences, with shadows, and of large size. Through ERP analysis and source localization, we have established that different exposure signs elicit distinct brain activation patterns. The ERP analysis revealed a strong correlation between the latency of the P300 component and the visibility of the exposure signs. Furthermore, our source localization findings indicate that exposure signs alter the current density distribution within the cortex, with shadows causing significantly higher activation in the frontal lobe compared to other conditions. The study also uncovered a pronounced right-brain laterality in subjects during target identification. By employing an LSTM neural network, we successfully differentiated EEG signals triggered by various exposure signs, achieving a classification accuracy of up to 96.4%. These results not only suggest that analyzing the P300 latency and cortical current distribution can differentiate the degree of visibility of target exposure signs, but also demonstrate the potential of using EEG characteristics to identify key exposure signs in camouflaged targets. This provides crucial insights for developing auxiliary camouflage strategies.

Modulating Vertebrate Physiology by Genomic Fine-Tuning of GPCR Functions.

G protein-coupled receptors (GPCRs) play a crucial role as membrane receptors, facilitating the communication of eukaryotic species with their environment and regulating cellular and organ interactions. Consequently, GPCRs hold immense potential in contributing to adaptation to ecological niches and responding to environmental shifts. Comparative analyses of vertebrate genomes reveal patterns of GPCR gene loss, expansion, and signatures of selection. Integrating this genomic data with insights from functional analyses of gene variants enables the interpretation of genotype-phenotype correlations. This review underscores the involvement of GPCRs in adaptive processes, presenting numerous examples of how alterations in GPCR functionality influence vertebrate physiology, or conversely, how environmental changes impact GPCR functions. The findings demonstrate that modifications in GPCR function contribute to adapting to aquatic, arid, and nocturnal habitats, influencing camouflage strategies, and specializing in particular dietary preferences. Furthermore, the adaptability of GPCR functions provides an effective mechanism in facilitating past, recent, or ongoing adaptations in animal domestication and human evolution and should be considered in therapeutic strategies and drug development.

A circuit protection method based on replacing minterms with combinatorial circuits

This paper introduces an integrated circuit camouflage strategy based on the minterms. The modified circuit can be well protected against SAT attacks. The method consists of two main steps: finding minterms and perturbing the circuit. This approach applies to multi-output circuits. This method allows for quick and accurate identification of minterms and the generation of circuits with significantly enhanced output disturbances. Experiments conducted on the OpenSPARC microprocessor using the ISCAS'85 and ISCAS'89 benchmark circuits demonstrate the effectiveness of our method. The time to find a minterm is only about 0.03s. The average correctness of the search is more than 90 %. The combinatorial circuit is resistant to SAT attack after replacement of the minterm. Moreover, the perturbation of circuit outputs significantly surpasses that of the original CamoPerturb structure, with one of the most notable improvements being an enhancement of approximately 330 times.

Iron gallic acid biomimetic nanoparticles for targeted magnetic resonance imaging.

Developing T1-weighted magnetic resonance imaging (MRI) contrast agents with enhanced biocompatibility and targeting capabilities is crucial owing to concerns over current agents' potential toxicity and suboptimal performance. Drawing inspiration from "biomimetic camouflage," we isolated cell membranes (CMs) from human glioblastoma (T98G) cell lines via the extrusion method to facilitate homotypic glioma targeting. At an 8:1 mass ratio of ferric chloride hexahydrate to gallic acid (GA), the resulting iron (Fe)-GA nanoparticles (NPs) proved effective as a T1-weighted MRI contrast agent. T98G CM-coated Fe-GA NPs demonstrated improved homotypic glioma targeting, validated through Prussian blue staining and in vitro MRI. This biomimetic camouflage strategy holds promise for the development of targeted theranostic agents in a safe and effective manner.

3D printed micro-structured hydrogel device with transmittance-changeable soft ‘armor’ camouflage for dual-encryption

Hydrogel-based physical dual-encryption typically relies on the reversible shape-deformation of polymer chains for the decryption. However, the stored information is confronted by indecipherability at the microscale because the intrinsic relaxation of polymer chains would disrupt the fidelity of encoded information. Inspired by female Doryteuthis opalescens squid’s camouflage strategy (i.e., switching a stripe on its mantle from nearly transparent to opaque white), we devised a reversible transmittance-changeable hydrogel layer to fully cover the mono-encrypted information layer for dual-encryption. The micro-structured hydrogel was manufactured via 3D printing to encode the information, which can be decoded by UV-induced fluorescent emission. Then, the white camouflage hydrogel was constructed to conceal the mono-encrypted layer, which will not affect the information encoding layer during the reversible polymer chain mobility. The information can be decoded with alkaline solution and UV irradiation in a rapid speed, i.e., in 4 min, with good reusability. Moreover, the information was accurately unveiled even at microscale resolution, holding great promise for high-level encryption at the device level.

Death simulation behavior of the lizard Lygodactylus klugei of the Gekkonidae (Reptilia: Squamata) family in northeastern Brazil

Natural selection favors primary defense strategies that reduce the chance of prey being spotted and discovered by a potential predator, such as camouflage, aposematism, and secondary defense strategies that include tail loss and escape, immobility, and thanatosis. The behavior of thanatosis (playing dead) or tonic immobility (body paralysis) is a strategy adopted by the prey, in which the animal simulates immobility to avoid being ingested. This simulation is effective against visually oriented predators or predators that do not feed on dead prey. Belonging to a complex of cryptic species, Lygodactylus klugei is a gecko that has a wide distribution in Northeast Brazil, occupying areas of the Caatinga and Cerrado, and that has a diurnal habit. On August 25th and September 2nd, 2021, three individuals of L. klugei were observed exhibiting thanatosis behavior during plant suppression work in the Curaçá municipality, Bahia state, Brazil. This behavior is reported for the first time in for L. klugei, and the species may use it if it is unable to escape from visually oriented predators. However, we suggest that future observations may generate new hypotheses about the benefits of this behavior in the species. Our observation adds important data to the behavioral repertoire of lizards from the Gekkonidae family, providing important natural history data to try to understand the defense mechanisms adopted by lizards in general.

Role of body size and shape in animal camouflage.

Animal camouflage serves a dual purpose in that it enhances both predation efficiency and anti-predation strategies, such as background matching, disruptive coloration, countershading, and masquerade, for predators and prey, respectively. Although body size and shape determine the appearance of animals, potentially affecting their camouflage effectiveness, research over the past two centuries has primarily focused on animal coloration. Over the past two decades, attention has gradually shifted to the impact of body size and shape on camouflage. In this review, we discuss the impact of animal body size and shape on camouflage and identify research issues and challenges. A negative correlation between background matching effectiveness and an animal's body size has been reported, whereas flatter body shapes enhance background matching. The effectiveness of disruptive coloration is also negatively correlated with body size, whereas irregular body shapes physically disrupt the body outline, reducing the visibility of true edges and making it challenging for predators to identify prey. Countershading is most likely in larger mammals with smaller individuals, whereas body size is unrelated to countershading in small-bodied taxa. Body shape influences a body reflectance, affecting the form of countershading coloration exhibited by animals. Animals employing masquerade achieve camouflage by resembling inanimate objects in their habitats in terms of body size and shape. Empirical and theoretical research has found that body size affects camouflage strategies by determining key aspects of an animal's appearance and predation risk and that body shape plays a role in the form and effectiveness of camouflage coloration. However, the mechanisms underlying these adaptations remain elusive, and a relative dearth of research on other camouflage strategies. We underscore the necessity for additional research to investigate the interplay between animal morphology and camouflage strategies and their coevolutionary development, and we recommend directions for future research.

Cellular uptake and in vivo distribution of mesenchymal-stem-cell-derived extracellular vesicles are protein corona dependent.

Extracellular vesicles (EVs) derived from mesenchymal stem cells are promising nanotherapeutics in liver diseases due to their regenerative and immunomodulatory properties. Nevertheless, a concern has been raised regarding the rapid clearance of exogenous EVs by phagocytic cells. Here we explore the impact of protein corona on EVs derived from two culturing conditions in which specific proteins acquired from media were simultaneously adsorbed on the EV surface. Additionally, by incubating EVs with serum, simulating protein corona formation upon systemic delivery, further resolved protein corona-EV complex patterns were investigated. Our findings reveal the potential influences of corona composition on EVs under in vitro conditions and their in vivo kinetics. Our data suggest that bound albumin creates an EV signature that can retarget EVs from hepatic macrophages. This results in markedly improved cellular uptake by hepatocytes, liver sinusoidal endothelial cells and hepatic stellate cells. This phenomenon can be applied as a camouflage strategy by precoating EVs with albumin to fabricate the albumin-enriched protein corona-EV complex, enhancing non-phagocytic uptake in the liver. This work addresses a critical challenge facing intravenously administered EVs for liver therapy by tailoring the protein corona-EV complex for liver cell targeting and immune evasion.

Is There a Bias Towards Males in the Diagnosis of Autism? A Systematic Review and Meta-Analysis.

Autism is more frequently diagnosed in males, with evidence suggesting that females are more likely to be misdiagnosed or underdiagnosed. Possibly, the male/female ratio imbalance relates to phenotypic and camouflaging differences between genders. Here, we performed a comprehensive approach to phenotypic and camouflaging research in autism addressed in two studies. First (Study 1 - Phenotypic Differences in Autism), we conducted a systematic review and meta-analysis of gender differences in autism phenotype. The electronic datasets Pubmed, Scopus, Web of Science, and PsychInfo were searched. We included 67 articles that compared females and males in autism core symptoms, and in cognitive, socioemotional, and behavioural phenotypes. Autistic males exhibited more severe symptoms and social interaction difficulties on standard clinical measures than females, who, in turn, exhibited more cognitive and behavioural difficulties. Considering the hypothesis of camouflaging possibly underlying these differences, we then conducted a meta-analysis of gender differences in camouflaging (Study 2 - Camouflaging Differences in Autism). The same datasets as the first study were searched. Ten studies were included. Females used more compensation and masking camouflage strategies than males. The results support the argument of a bias in clinical procedures towards males and the importance of considering a 'female autism phenotype'-potentially involving camouflaging-in the diagnostic process.

Camouflaging attenuated Salmonella by cryo-shocked macrophages for tumor-targeted therapy

Live bacteria-mediated antitumor therapies mark a pivotal point in cancer immunotherapy. However, the difficulty in reconciling the safety and efficacy of bacterial therapies has limited their application. Improving bacterial tumor-targeted delivery while maintaining biosafety is a critical hurdle for the clinical translation of live microbial therapy for cancer. Here, we developed “dead” yet “functional” Salmonella-loaded macrophages using liquid nitrogen cold shock of an attenuated Salmonella typhimurium VNP20009-contained macrophage cell line. The obtained “dead” macrophages achieve an average loading of approximately 257 live bacteria per 100 cells. The engineered cells maintain an intact cellular structure but lose their original pathogenicity, while intracellular bacteria retain their original biological activity and are delay freed, followed by proliferation. This “Trojan horse”-like bacterial camouflage strategy avoids bacterial immunogenicity-induced neutrophil recruitment and activation in peripheral blood, reduces the clearance of bacteria by neutrophils and enhances bacterial tumor enrichment efficiently after systemic administration. Furthermore, this strategy also strongly activated the tumor microenvironment, including increasing antitumor effector cells (including M1-like macrophages and CD8+ Teffs) and decreasing protumor effector cells (including M2-like macrophages and CD4+ Tregs), and ultimately improved antitumor efficacy in a subcutaneous H22 tumor-bearing mouse model. The cryo-shocked macrophage-mediated bacterial delivery strategy holds promise for expanding the therapeutic applications of living bacteria for cancer.

Antipredator defences in motion: animals reduce predation risks by concealing or misleading motion signals.

Motion is a crucial part of the natural world, yet our understanding of how animals avoid predation whilst moving remains rather limited. Although several theories have been proposed for how antipredator defence may be facilitated during motion, there is often a lack of supporting empirical evidence, or conflicting findings. Furthermore, many studies have shown that motion often 'breaks' camouflage, as sudden movement can be detected even before an individual is recognised. Whilst some static camouflage strategies may conceal moving animals to a certain extent, more emphasis should be given to other modes of camouflage and related defences in the context of motion (e.g. flicker fusion camouflage, active motion camouflage, motion dazzle, and protean motion). Furthermore, when motion is involved, defence strategies are not necessarily limited to concealment. An animal can also rely on motion to mislead predators with regards to its trajectory, location, size, colour pattern, or even identity. In this review, we discuss the various underlying antipredator strategies and the mechanisms through which they may be linked to motion, conceptualising existing empirical and theoretical studies from two perspectives - concealing and misleading effects. We also highlight gaps in our understanding of these antipredator strategies, and suggest possible methodologies for experimental designs/test subjects (i.e. prey and/or predators) and future research directions.

The association between social camouflage and mental health among autistic people in Japan and the UK: a cross-cultural study

BackgroundTo examine the relationship between social camouflage and mental health in Japanese autistic adults and make an international comparison with a sample from the UK.MethodsThis study analysed secondary data of participants with a self-reported diagnosis of autism from Japan (N = 210; 123 men and 87 women) and the UK (N = 305; 181 women, 104, men, and 18 nonbinary). The relationships between the quadratic term of the Camouflaging Autistic Traits Questionnaire and mental health scales, including depression and anxiety, were assessed.ResultsThe UK sample showed linear relationships, whereas the Japanese sample showed significant nonlinear relationships. The quadratic terms of the Camouflaging Autistic Traits Questionnaire slightly explained generalised anxiety (β = .168, p = .007), depression (β = .121, p = .045), and well-being (β = − .127, p = .028). However, they did not explain the association between social anxiety and the Camouflaging Autistic Traits Questionnaire.LimitationsParticipants had self-reported diagnoses, and while the autism-spectrum quotient provides a cut-off value for screening, it does not enable confirming diagnoses. Mean scores of the Japanese version of the Camouflaging Autistic Traits Questionnaire were lower as compared to the original CAT-Q, which implies that the social camouflage strategy types used by autistic people in Japan and the UK could differ. The cross-sectional design limits causal inferences.ConclusionIn the UK, more social camouflage was associated with poorer mental health scores, whereas too little or too much social camouflage was associated with a low mental health score in Japan. The Japanese population is seemingly less aware of and educated on autistic characteristics and considers ‘average’ behaviour a good thing. This could influence Japanese autistic people’s social camouflage use, differing from that of autistic people in the UK. The differences in the relationship between social camouflage and mental health between Japan and the UK could be associated with national-level divergence regarding the culture of autism.

Background matching can reduce responsiveness of jumping spiders to stimuli in motion.

Motion and camouflage were previously considered to be mutually exclusive, as sudden movements can be easily detected. Background matching, for instance, is a well-known, effective camouflage strategy where the colour and pattern of a stationary animal match its surrounding background. However, background matching may lose its efficacy when the animal moves, as the boundaries of the animal become more defined against its background. Recent evidence shows otherwise, as camouflaged objects can be less detectable than uncamouflaged objects even while in motion. Here, we explored whether the detectability of computer-generated stimuli varies with the speed of motion, background (matching and unmatching) and size of stimuli in six species of jumping spiders (Araneae: Salticidae). Our results showed that, in general, the responsiveness of all six salticid species tested decreased with increasing stimulus speed regardless of whether the stimuli were conspicuous or camouflaged. Importantly, salticid responses to camouflaged stimuli were significantly lower compared with those to conspicuous stimuli. There were significant differences in motion detectability across species when the stimuli were conspicuous, suggesting differences in visual acuity in closely related species of jumping spiders. Furthermore, small stimuli elicited significantly lower responses than large stimuli across species and speeds. Our results thus suggest that background matching is effective even when stimuli are in motion, reducing the detectability of moving stimuli.

Renaturing the City in Architectural Design Through Camouflage Strategy

The urban environment is built on the natural environment. The presence of architectural design dominates the urban environment through materials. The solid nature of the material causes the urban environment to be unable to absorb rainwater optimally. Decreased soil quality can have a negative impact on humans. Therefore, naturalization of the urban environment is needed to reduce the negative impact of the environment on humans. This research explores the optimal form of architectural design to channel rainwater into the ground. This research is qualitative in nature. The research method used is experimental. Experiments were carried out to find the optimal architectural design form through small-scale models. The research results are in the form of a full-slooping architectural design that can maximize water absorption into the soil. This is caused by the application of a camouflage strategy in finding the most optimal shape. This allows renaturalizing the urban environment to reduce the risk of negative impacts on humans.

Adapting genetic algorithms for artificial evolution of visual patterns under selection from wild predators.

Camouflage is a widespread and well-studied anti-predator strategy, yet identifying which patterns provide optimal protection in any given scenario remains challenging. Besides the virtually limitless combinations of colours and patterns available to prey, selection for camouflage strategies will depend on complex interactions between prey appearance, background properties and predator traits, across repeated encounters between co-evolving predators and prey. Experiments in artificial evolution, pairing psychophysics detection tasks with genetic algorithms, offer a promising way to tackle this complexity, but sophisticated genetic algorithms have so far been restricted to screen-based experiments. Here, we present methods to test the evolution of colour patterns on physical prey items, under selection from wild predators in the field. Our techniques expand on a recently-developed open-access pattern generation and genetic algorithm framework, modified to operate alongside artificial predation experiments. In this system, predators freely interact with prey, and the order of attack determines the survival and reproduction of prey patterns into future generations. We demonstrate the feasibility of these methods with a case study, in which free-flying birds feed on artificial prey deployed in semi-natural conditions, against backgrounds differing in three-dimensional complexity. Wild predators reliably participated in this experiment, foraging for 11 to 16 generations of artificial prey and encountering a total of 1,296 evolved prey items. Changes in prey pattern across generations indicated improvements in several metrics of similarity to the background, and greater edge disruption, although effect sizes were relatively small. Computer-based replicates of these trials, with human volunteers, highlighted the importance of starting population parameters for subsequent evolution, a key consideration when applying these methods. Ultimately, these methods provide pathways for integrating complex genetic algorithms into more naturalistic predation trials. Customisable open-access tools should facilitate application of these tools to investigate a wide range of visual pattern types in more ecologically-relevant contexts.

A Living Lab in the Quebec’s Homes for older adults with a neurocognitive disorder: aiming to improve the personalization of long‐term care and the self‐determination of residents and their relatives

AbstractBackgroundThe “ Quebec’s Homes for Older Adults with a Neurocognitive Disorder ” (QHOA) model aims to improve the quality of residential and long‐term care environments for people losing their autonomy. Considering the major paradigm shift behind the QHOA philosophy, it seemed timely to co‐construct a Living Lab‐type structural organisation whose main mission will be to contribute to the sustainability of the new model.ObjectivesSince 2021, we have been co‐constructing links between scientists, decision‐makers, staff (carers, cooks, housekeepers, etc.), QHOA stakeholders and, above all, the community and its seniors. Our structure is a Living Lab and the main objective is to cyclically and participatively co‐construct a set of solutions applicable to QHOAs. Our work will encourage the design and development of sustainable solutions by considering human (e.g., self‐determination, personalization of care), environmental (e.g., layout and design, camouflage strategies), technological (e.g., sensors, cameras, connected watches and scales, artificial intelligence, software for care and medication), work organization, and continuous training of stakeholders.ResultsThe co‐construction process involved more than 40 researchers, clinicians, decision‐makers, or stakeholders. We have all been able to delineate the structure of the Living Lab and how knowledge will be disseminated, rallied, and promoted. This presentation will resume the main steps (including successes and challenges) of our work.ImplicationsA Living Lab is a place for collaboration, exchange, and co‐creation. The actors in the field have the most relevant knowledge of the living context in which the projects will be deployed. Our intersectoral team (20 fields of expertise) will provide the scientific knowledge to ensure the sustainability and ongoing development of the QHOA model.

Crypsis by background matching and disruptive coloration as drivers of substrate occupation in sympatric Amazonian bark praying mantises

Background matching and disruptive coloration are common camouflage strategies in nature, but few studies have accurately measured their protective value in living organisms. Amazon's Bark praying mantises exhibit colour patterns matching whitish and greenish-brown tree trunks. We tested the functional significance of background matching and disruptive coloration of different praying mantis morphospecies (white, grey and green) detected by DNA barcoding. Through image analysis, avian visual models and field experiments using humans as potential predators, we explored whether the background occupation of mantises provides camouflage against predation. Data were obtained for individuals against their occupied tree trunks (whitish or greenish-brown) and microhabitats (lichen or bryophyte patches), compared to non-occupied trunks. White and grey mantises showed lower colour contrasts against occupied trunks at the scale of tree trunk, with no differences in luminance contrasts. Conversely, green mantises showed lower colour and luminance contrasts against microhabitats and also exhibited high edge disruption against greenish-brown trunks. The camouflage of white and green mantis models against colour-matching trunks increased search time and reduced encounter distance of human predators. We highlight the importance of camouflage strategies at different spatial scales to enhance individual survival against predators. Specifically, we present a stunning study system to investigate the relationship of phylogenetically related species that use camouflage in sympatry.

Camouflage, self-esteem and gratitude in young adults with varying degrees of autistic traits in Poland

Autistic spectrum conditions (ASC) imply functioning difficulties in adulthood due to the fact that they are caused by early-onset problems in social communication, unusually restricted repetitive behavior, and narrow interests. Living with ASC might be difficult for young adults who face specific developmental tasks, such as undertaking a professional career and engaging in social and civic responsibilities. Because of the need to hide their dysfunctions and to conform to social norms and conventions, affected people use camouflage strategies. In order to improve their well-being and functioning, they may also use the regulatory function of self-esteem and gratitude. The presented research carried out in Poland aimed to determine the relations between the intensity of camouflage, self-esteem, and gratitude and to test for differences in the levels of these variables, taking into consideration the intensity of the autism spectrum conditions (ASC). The study comprised a total of 104 young adults (68 women = 65.38%, and 36 men = 34.62%) who graduated from secondary or tertiary education aged between 19 and 35 years. The entire group was divided into two subgroups based on the screening questionnaire Autism Spectrum Quotient (AQ10), a ten-item abridged version. One subgroup consisted of 52 adults with a high intensity of autistic traits, and the other consisted of individuals with a low intensity of autistic traits. The results showed a correlation between the level of autism spectrum conditions and camouflage. The level of camouflage was significantly higher in the subgroup with an increased severity of autistic traits compared with the subgroup with a low severity. In contrast, no significant differences were detected between the subgroups in the levels of self-esteem and gratitude, nor were any linear correlations between spectrum conditions and self-esteem and gratitude found.