Effective Cooperation and Scalability in Multi-Robot Teams for Automatic Patrolling of Infrastructures

Tese de doutoramento em Engenharia Electrotécnica e de Computadores, apresentada ao Departamento de Engenharia Electrotécnica e de Computadores da Faculdade de Ciências e Tecnologia da Universidade de CoimbraIn the digital era that we live in, advances in technology have proliferated throughout our society, quickening the completion of tasks that were painful in the old days, improving solutions to the everyday problems that we face, and generally assisting human beings both in their professional and personal life. Robotics is a clear example of a broad technological field that evolves every day. In fact, scientists predict that in the upcoming few decades, robots will naturally interact and coexist alongside human beings. While it is true that robots already have a strong presence in industrial environments, e.g., robotic arms for manufacturing, the average person still looks upon robots with suspicion, since they are not acquainted by such type of technology. In this thesis, the author deploys teams of mobile robots in indoor scenarios to cooperatively perform patrolling missions, which represents an effort to bring robots closer to humans and assist them in monotonous or repetitive tasks, such as supervising and monitoring indoor infrastructures or simply cooperatively cleaning floors. In this context, the team of robots should be able to sense the environment, localize and navigate autonomously between way points while avoiding obstacles, incorporate any number of robots, communicate actions in a distributed way and being robust not only to agent failures but also communication failures, so as to effectively coordinate to achieve optimal collective performance. The referred capabilities are an evidence that such systems can only prove their reliability in real-world environments if robots are endowed with intelligence and autonomy. Thus, the author follows a line of research where patrolling units have the necessary tools for intelligent decision-making, according to the information of the mission, the environment and teammates' actions, using distributed coordination architectures. An incremental approach is followed. Firstly, the problem is presented and the literature is deeply studied in order to identify potential weaknesses and research opportunities, backing up the objectives and contributions proposed in this thesis. Then, problem fundamentals are described and benchmarking of multi-robot patrolling algorithms in realistic conditions is conducted. In these earlier stages, the role of different parameters of the problem, like environment connectivity, team size and strategy philosophy, will become evident through extensive empirical results and statistical analysis. In addition, scalability is deeply analyzed and tied with inter-robot interference and coordination, imposed by each patrolling strategy. After gaining sensibility to the problem, preliminary models for multi-robot patrol with special focus on real-world application are presented, using a Bayesian inspired formalism. Based on these, distributed strategies that lead to superior team performance are described. Interference between autonomous agents is explicitly dealt with, and the approaches are shown to scale to large teams of robots. Additionally, the robustness to agent and communication failures is demonstrated, as well as the flexibility of the model proposed. In fact, by later generalizing the model with learning agents and maintaining memory of past events, it is then shown that these capabilities can be inherited, while at the same time increasing team performance even further and fostering adaptability. This is verified in simulation experiments and real-world results in a large indoor scenario. Furthermore, since the issue of team scalability is highly in focus in this thesis, a method for estimating the optimal team size in a patrolling mission, according to the environment topology is proposed. Upper bounds for team performance prior to the mission start are provided, supporting the choice of the number of robots to be used so that temporal constraints can be satisfied. All methods developed in this thesis are tested and corroborated by experimental results, showing the usefulness of employing cooperative teams of robots in real-world environments and the potential for similar systems to emerge in our society.FCT - SFRH/BD/64426/200

MRsensing: environmental monitoring and context recognition with cooperative mobile robots in catastrophic incidents

Dissertação de Mestrado em Engenharia Electrotécnica e de Computadores, apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraMulti-sensor information fusion theory concerns the environmental perception activities to combine data from multiple sensory resources. Humans, as any other animals, gather information from the environment around them using different biological sensors. Combining them allows structuring the decisions and actions when interacting with the environment. Under disaster conditions, effective mult-robot information sensor fusion can yield a better situation awareness to support the collective decision-making. Mobile robots can gather information from the environment by combining data from different sensors as a way to organize decisions and augment human perception. The is especially useful to retrieve contextual environmental information in catastrophic incidents where human perception may be limited (e.g., lack of visibility). To that end, this work proposes a specific configuration of sensors assembled in a mobile robot, which can be used as a proof of concept to measure important environmental variables in an urban search and rescue (USAR) mission, such as toxic gas density, temperature gradient and smoke particles density. This data is processed through a support vector machine classifier with the purpose of detecting relevant contexts in the course of the mission. The outcome provided by the experiments conducted with TraxBot and Pioneer-3DX robots under the Robot Operating System framework opens the door for new multi-robot applications on USAR scenarios. This work was developed within the CHOPIN research project1 which aims at exploiting the cooperation between human and robotic teams in catastrophic accidents.O tema da fusão sensorial abrange a perceção ambiental para combinar dados de vários recursos naturais. Os seres humanos, como todos os outros animais, recolhem informações do seu redor, utilizando diferentes sensores biológicos. Combinando-se informação dos diferentes sensores é possível estruturar decisões e ações ao interagir com o meio ambiente. Sob condições de desastres, a fusão sensorial de informação eficaz proveniente de múltiplos robôs pode levar a um melhor reconhecimento da situação para a tomada de decisão coletiva. Os robôs móveis podem extrair informações do ambiente através da combinação de dados de diferentes sensores, como forma de organizar as decisões e aumentar a perceção humana. Isto é especialmente útil para obter informações de contexto ambientais em cenários de catástrofe, onde a perceção humana pode ser limitada (por exemplo, a falta de visibilidade). Para este fim, este trabalho propõe uma configuração específica de sensores aplicados num robô móvel, que pode ser usado como prova de conceito para medir variáveis ambientais importantes em missões de busca e salvamento urbano (USAR), tais como a densidade do gás tóxico, gradiente de temperatura e densidade de partículas de fumo. Esta informação é processada através de uma máquina de vetores de suporte com a finalidade de classificar contextos relevantes no decorrer da missão. O resultado fornecido pelas experiências realizadas com os robôs TraxBot e Pioneer 3DX usando a arquitetura Robot Operating System abre a porta para novas aplicações com múltiplos robôs em cenários USAR

The length of esterifying alcohol affects the aggregation properties of chlorosomal bacteriochlorophylls

Chlorosomes, the main light-harvesting complexes of green photosynthetic bacteria, contain bacteriochlorophyll (BChl) molecules in the form of self-assembling aggregates. To study the role of esterifying alcohols in BChl aggregation we have prepared a series of bacteriochlorophyllide c (BChlide c) derivatives differing in the length of the esterifying alcohol (C1, C4, C8 and C12). Their aggregation behavior was studied both in polar (aqueous buffer) and nonpolar (hexane) environments and the esterifying alcohols were found to play an essential role. In aqueous buffer, hydrophobic interactions among esterifying alcohols drive BChlide c derivatives with longer chains into the formation of dimers, while this interaction is weak for BChlides with shorter esterifying alcohols and they remain mainly as monomers. All studied BChlide c derivatives form aggregates in hexane, but the process slows down with longer esterifying alcohols due to competing hydrophobic interactions with hexane molecules. In addition, the effect of the length of the solvent molecules (n-alkanes) was explored for BChl c aggregation. With an increasing length of n-alkane molecules, the hydrophobic interaction with the farnesyl chain becomes stronger, leading to a slower aggregation rate. The results show that the hydrophobic interaction is the driving force for the aggregation in an aqueous environment, while in nonpolar solvents it is the hydrophilic interaction.AVCR-CSIC joint project (Grant nº 2004CZ0001 and 2006CZ0019). Spanish Ministry of Education and Science (BF2004-04914-C02-02/BMC)Peer reviewe

Staphylococcal Toxins and Protein A Differentially Induce Cytotoxicity and Release of Tumor Necrosis Factor–α From Human Keratinocytes

It has been proposed that toxins and other bacterial protein products of Staphylococcus aureus can act as triggers or persistence factors in several inflammatory skin diseases. In this study, we examined the S. aureus isolates from the skin of patients with atopic dermatitis and psoriasis. We found that the bacterial isolates from these patients exihibited either characteristics superantigenic toxins or thermolabile toxins believed to be staphylococal α-toxin. All of these staphylococcal strains also secreted extracellular staphylococcal protein A. We found significant differences in the action of these toxins on human keratinocytes and keratinocyte cell lines. The superantigenic toxins toxic shock syndrome toxin–1, staphylococcal enterotoxins A and B, and exfoliative toxin–A. as well as staphylococcal protein A, did not induce significant cytotoxic damage in the keratinocyte cell line HaCaT, whereas the staphylococcal α-toxin produced profound cytotoxicity. Keratinocyte cytotoxity induced by staphylococcal α-toxin was time and concentration dependent and demonstrated the morphologic and functional characteristics of necrosis, not apoptosis. Addition of α-toxin to keratinocytes simultaneously induced cell lysis and tumor necrosis factor–α release into the medium within 30 min; apparently, it was constitutive tumor necrosis factor–α. On the other hand, superantigenic toxins and, in particular, protein A showed stimulation of tumor necrosis factor-α secretion in keratinocytes and release of this cytokine after 6–12h of incubation. Thus, staphylococcal protein A, α-toxin, and superantigenic toxins found in S. aureus isolates from patients with psoriasis and atopic dermatitis can produce direct pro-inflammatory effects on kerationcytes through the release of tumor necrosis factor–α. We propose that these effects may be relevant to the induction and persistence of lesions in these two disease

Increased Physical Activity and Reduced Pain with Spinal Cord Stimulation: a 12-Month Study

International Journal of Exercise Science 13(3): 1583-1594, 2020. The purpose of this study was to assess changes in pain and physical activity after replacing a traditional spinal cord stimulation (SCS) implantable pulse generator with a next generation SCS in patients for whom traditional SCS was no longer providing adequate relief of low back and/or leg pain. Subjects (n = 19) who reported that they were no longer receiving adequate relief from traditional SCS were implanted with a next generation SCS. Eighteen additional patients who were receiving relief from traditional SCS were also followed as a control. Both groups (next generation, traditional) were assessed for low-back and limb pain (visual analog scale) and daily physical activity (wearable accelerometer) at baseline and three, six, nine and 12 months following the SCS implant. Relative to baseline, next generation SCS subjects exhibited reductions (p ≤ 0.05 for all) in low-back pain (average reduction of 22%) at every time point, in leg pain (average reduction of 23%) at every time point except six months and increased physical activity (average increase of 57%) at three, six and nine months. As expected, there were no changes in pain or physical activity in the traditional SCS subjects (p ≥ 0.1). In conclusion, pain decreased, and physical activity increased in patients receiving a next generation SCS. Physical activity may serve as an objectively measured marker of pain

Novel haloarchaeal viruses from Lake Retba infecting Haloferax and Halorubrum species

The diversity of archaeal viruses is severely undersampled compared with that of viruses infecting bacteria and eukaryotes, limiting our understanding on their evolution and environmental impacts. Here, we describe the isolation and characterization of four new viruses infecting halophilic archaea from the saline Lake Retba, located close to Dakar on the coast of Senegal. Three of the viruses, HRPV10, HRPV11 and HRPV12, have enveloped pleomorphic virions and should belong to the family Pleolipoviridae, whereas the forth virus, HFTV1, has an icosahedral capsid and a long non-contractile tail, typical of bacterial and archaeal members of the order Caudovirales. Comparative genomic and phylogenomic analyses place HRPV10, HRPV11 and HRPV12 into the genus Betapleolipovirus, whereas HFTV1 appears to be most closely related to the unclassified Halorubrum virus HRTV-4. Differently from HRTV-4, HFTV1 encodes host-derived minichromosome maintenance helicase and PCNA homologues, which are likely to orchestrate its genome replication. HFTV1, the first archaeal virus isolated on a Haloferax strain, could also infect Halorubrum sp., albeit with an eightfold lower efficiency, whereas pleolipoviruses nearly exclusively infected autochthonous Halorubrum strains. Mapping of the metagenomic sequences from this environment to the genomes of isolated haloarchaeal viruses showed that these known viruses are underrepresented in the available viromes.Peer reviewe

Stopping rape: towards a comprehensive policy

The need to stop rape is pressing. Since it is the outcome of a wide range of practices and institutions in society, so too must be the policies to stop it. This important book offers a comprehensive guide to the international policies developed to stop rape, together with case study examples on how they work. The book engages with the law and criminal justice system, health services, specialised services for victim-survivors, and educational and cultural interventions, as well as how they can best be coordinated. It is informed by theory and evidence drawn from scholarship and practice from around the world. It will be of interest to a global readership of students, practitioners and policy makers as well as anyone who wants to know how rape can be stopped

Gendering Farmer Producer companies at the Agricultural Frontier of India: Empowerment or Burden?

Farmer Producer Companies (FPCs) are driving agricultural frontier expansions in India. Their main objectives are to mobilize small-scale farmers to collectivize and organize in order to gain collective bargaining power, in the process empowering farmers and eliminating middlemen. However, they have not established any demonstrable success in achieving these goals. This chapter seeks firstly, to draw transnational connections between agro-ecological transformations in India and larger market/capital expansions through FPCs, contextualized amidst national development goals for farmer empowerment, changing labor patterns, and ecological degradation. In doing so, it will, secondly, explore the gendered dimension of FPCs in India by analyzing how the process of establishing women-only FPCs by using mandatory inclusion as a participation tool can serve to disempower and further burden women. While mandatory involvement of women farmers on their Board of Directors as an empowerment strategy can prove crucial to enhancing women’s decision-making roles, this chapter asks whether such an inclusionary approach remains meaningful to achieve FPC success in a context where external support for women’s empowerment is not provided

Young Galaxy Candidates in the Hubble Frontier Fields. II. MACS J0416-2403

We searched for z ≳ 7 Lyman-break galaxies in the optical-to-mid-infrared Hubble Frontier Field and associated parallel field observations of the strong-lensing cluster MACS J0416−2403. We discovered 22 candidates, of which 6 lie at z ≳ 9 and 1 lies at z ≳ 10. Based on the Hubble and Spitzer photometry, all have secure photometric redshifts and a negligible probability of being at lower redshifts according to their peak-probability ratios, R. This substantial increase in the number of known high-redshift galaxies allows a solid determination of the luminosity function (LF) at z ≳ 8. The number of high-z candidates in the parallel field is considerably higher than that in the Abell 2744 parallel field. Our candidates have median stellar masses of log M_* ~ 8.44_(-0.31)^(+0.55) M_⊙, star formation rates (SFRs) of ~ 1.8_(-0.4)^(+0.5) M_⊙ yr^(−1), and SFR-weighted ages of ≾ 300_(-140)^(+70) Myr. Finally, we are able to put strong constraints on the z = 7, 8, 9, and 10 LFs. One of the objects in the cluster field is a z ≃ 10 candidate, with a magnification of μ ~ 20 ± 13. This object is likely the faintest z ~ 10 object known to date, allowing a first look into the extreme faint end (L ~ 0.04 L^*) of the z ~ 10 LF (It is named "Tayna" in the Aymara language)