CZECH WW2 CONCRETE FORTIFICATIONS: CORROSION PROCESSES AND REMEDIATION METHOD BASED ON CRYSTALLIZING COATING

Concrete is a relatively new structural material, hence the remediation of concrete structures is very rare. There are a lot of concrete fortifications in the Czech Republic, which were built just before WW2. These bunkers formed a long defensive line along the Czechoslovak borders as a protection against Hitler’s army. Today, after 80 years, many of the bunkers are listed as Czech national technical monuments with a strict protection of their historical authenticity. The article describes the technical survey and the possible conservation method of a selected concrete fortification, which exhibits a number of moisture related problems. The studied two-storey, heavily fortified bunker is situated close to the northern border of the Czech Republic, former Czechoslovakia. A detailed survey of the building includes the analysis of the interior environment parameters and laboratory testing of the used concrete. A long-term diagnosis identified the main problem, which lies in the inhomogeneity of the used concrete and the relating massive water ingress. However, the monitored bunker currently does not serve as a military structure and, therefore, a simple solution to improve the internal environment was suggested on the basis of the conducted measurements. With respect to the main causes of failures, the authors suggested a conservation method based on using a crystallizing coating. The suitability of the method was first verified under laboratory conditions and then also on the real bunker

Challenges and Remedies to Privacy and Security in AIGC: Exploring the Potential of Privacy Computing, Blockchain, and Beyond

Artificial Intelligence Generated Content (AIGC) is one of the latest achievements in AI development. The content generated by related applications, such as text, images and audio, has sparked a heated discussion. Various derived AIGC applications are also gradually entering all walks of life, bringing unimaginable impact to people's daily lives. However, the rapid development of such generative tools has also raised concerns about privacy and security issues, and even copyright issues in AIGC. We note that advanced technologies such as blockchain and privacy computing can be combined with AIGC tools, but no work has yet been done to investigate their relevance and prospect in a systematic and detailed way. Therefore it is necessary to investigate how they can be used to protect the privacy and security of data in AIGC by fully exploring the aforementioned technologies. In this paper, we first systematically review the concept, classification and underlying technologies of AIGC. Then, we discuss the privacy and security challenges faced by AIGC from multiple perspectives and purposefully list the countermeasures that currently exist. We hope our survey will help researchers and industry to build a more secure and robust AIGC system.Comment: 43 pages, 10 figure

Adversarial Examples in the Physical World: A Survey

Deep neural networks (DNNs) have demonstrated high vulnerability to adversarial examples. Besides the attacks in the digital world, the practical implications of adversarial examples in the physical world present significant challenges and safety concerns. However, current research on physical adversarial examples (PAEs) lacks a comprehensive understanding of their unique characteristics, leading to limited significance and understanding. In this paper, we address this gap by thoroughly examining the characteristics of PAEs within a practical workflow encompassing training, manufacturing, and re-sampling processes. By analyzing the links between physical adversarial attacks, we identify manufacturing and re-sampling as the primary sources of distinct attributes and particularities in PAEs. Leveraging this knowledge, we develop a comprehensive analysis and classification framework for PAEs based on their specific characteristics, covering over 100 studies on physical-world adversarial examples. Furthermore, we investigate defense strategies against PAEs and identify open challenges and opportunities for future research. We aim to provide a fresh, thorough, and systematic understanding of PAEs, thereby promoting the development of robust adversarial learning and its application in open-world scenarios.Comment: Adversarial examples, physical-world scenarios, attacks and defense

Accounting narratives and impression management on social media

In this paper, we examine the defensive and assertive impression management strategies and the impact of firm performance on accounting narratives by investigating the earnings disclosures of FTSE 100 companies on Twitter. Social media has become the prevailing venue for organisational self-presentation because it provides firms with more control over the image they intend to establish and maintain through the communication and content they deliver online. Our findings show that firms minimise the disclosures of negative information but employ various patterns and dissemination techniques to emphasise positive information. Specifically, improving performers are more willing to post and disseminate earnings-related tweets to achieve a higher degree of stakeholder engagement than declining performers. Based on these findings, we conclude that firms present themselves on social media opportunistically to construct a positive public image

Leaf trichomes affect caterpillar feeding in an instar-specific manner

Leaf trichomes play well-established roles in defense against insect herbivores, both as a physical barrier that impedes herbivore movement and by mediating chemical defenses. However, little work has examined how different trichome types influence herbivory by herbivores at different stages of development. We examined whether caterpillar instar and trichome type (glandular or non-glandular) affected the ability of the specialist herbivore caterpillar Manduca sexta to initiate feeding on 11 Solanaceous species exhibiting variation in the density and type of leaf trichomes. Our results suggest that non-glandular trichomes are far more effective than glandular trichomes in deterring the initiation of feeding by first- and second-instar caterpillars. Meanwhile, neither glandular nor non-glandular trichomes significantly affected the ability of third-instar caterpillars to commence feeding. These findings suggest that while non-glandular trichomes deter feeding initiation by early instar caterpillars, the contribution of both trichomes on later instars may depend on effects after feeding initiation