Learning a Behavioral Repertoire from Demonstrations

International audienceImitation Learning (IL) is a machine learning approach to learn a policy from a set of demonstrations. IL can be useful to kick-start learning before applying reinforcement learning (RL) but it can also be useful on its own, e.g. to learn to imitate human players in video games. Despite the success of systems that use IL and RL, how such systems can adapt in-between game rounds is a neglected area of study but an important aspect of many strategy games. In this paper, we present a new approach called Behavioral Repertoire Imitation Learning (BRIL) that learns a repertoire of behaviors from a set of demonstrations by augmenting the state-action pairs with behavioral descriptions. The outcome of this approach is a single neural network policy conditioned on a behavior description that can be precisely modulated. We apply this approach to train a policy on 7,777 human demonstrations for the build-order planning task in StarCraft II. Dimensionality reduction is applied to construct a low-dimensional behavioral space from a high-dimensional description of the army unit composition of each human replay. The results demonstrate that the learned policy can be effectively manipulated to express distinct behaviors. Additionally, by applying the UCB1 algorithm, the policy can adapt its behavior-in-between games-to reach a performance beyond that of the traditional IL baseline approach

The Politics of Wildlife in Infrastructure Construction

Across many construction projects, and especially infrastructure projects, efforts to mitigate the potential loss of biodiversity and habitat are significant, and at times controversial. In our paper we do not propose to gauge the success or failure of this effort; rather we are interested in fleshing out some conceptual approaches via Actor- Network Theory through which infrastructure projects can start to address a series of overlooked questions. Some of these questions are firmly located within the realm of construction project management: are animals considered project risks or stakeholders; is wildlife always simply a retrospective cost to a project or can it proactively benefit a project, can we ever manage wildlife, and if so how? These questions in turn lead us to engage with wider debates found in the margins between the social and biological sciences on the distinction between Nature and Politics: to what extent should we seek a place for animals in politics and how can we live with them ethically. Thus far, very little research has addressed the interplay of humans and animals within construction projects. Instead those interested in the politics and ethics of human-animal relations, or Animal Studies, have focussed far more on stable and contained sites, whether organisations like zoos, farms or laboratories, or other places like homes and parks. These largely ethnographic studies inevitably perhaps downplay the unplanned, unexpected and highly politically and ethically charged collision of hitherto rather separate human and animal geographies. Yet, as we argue here, it is often along such colliding spaces, where animal geographies are unexpectedly found at the heart of human projects, that we ask and answer many of the above questions around our respect and response to both animals, and indeed other humans. In this paper we will examine such encounters conceptually, with reference to two infrastructure projects, and discuss their relevance to both construction project management and broader work on the politics of animals

Impact of peptide:HLA complex stability for the identification of SARS-CoV-2-specific CD8⁺T cells.

Induction of a lasting protective immune response is dependent on presentation of epitopes to patrolling T cells through the HLA complex. While peptide:HLA (pHLA) complex affinity alone is widely exploited for epitope selection, we demonstrate that including the pHLA complex stability as a selection parameter can significantly reduce the high false discovery rate observed with predicted affinity. In this study, pHLA complex stability was measured on three common class I alleles and 1286 overlapping 9-mer peptides derived from the SARS-CoV-2 Spike protein. Peptides were pooled based on measured stability and predicted affinity. Strikingly, stability of the pHLA complex was shown to strongly select for immunogenic epitopes able to activate functional CD8+T cells. This result was observed across the three studied alleles and in both vaccinated and convalescent COVID-19 donors. Deconvolution of peptide pools showed that specific CD8+T cells recognized one or two dominant epitopes. Moreover, SARS-CoV-2 specific CD8+T cells were detected by tetramer-staining across multiple donors. In conclusion, we show that stability analysis of pHLA is a key factor for identifying immunogenic epitopes

Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

EFSA was asked to update the 2015 EFSA risk assessment on Xylella fastidiosa for the territory of the EU. In particular, EFSA was asked to focus on potential establishment, short‐ and long‐range spread, the length of the asymptomatic period, the impact of X. fastidiosa and an update on risk reduction options. EFSA was asked to take into account the different subspecies and Sequence Types of X. fastidiosa. This was attempted throughout the scientific opinion but several issues with data availability meant that this could only be partially achieved. Models for risk of establishment showed most of the EU territory may be potentially suitable for X. fastidiosa although southern EU is most at risk. Differences in estimated areas of potential establishment were evident among X. fastidiosa subspecies, particularly X. fastidiosa subsp. multiplex which demonstrated areas of potential establishment further north in the EU. The model of establishment could be used to develop targeted surveys by Member States. The asymptomatic period of X. fastidiosa varied significantly for different host and pathogen subspecies combinations, for example from a median of approximately 1 month in ornamental plants and up to 10 months in olive, for pauca. This variable and long asymptomatic period is a considerable limitation to successful detection and control, particularly where surveillance is based on visual inspection. Modelling suggested that local eradication (e.g. within orchards) is possible, providing sampling intensity is sufficient for early detection and effective control measures are implemented swiftly (e.g. within 30 days). Modelling of long‐range spread (e.g. regional scale) demonstrated the important role of long‐range dispersal and the need to better understand this. Reducing buffer zone width in both containment and eradication scenarios increased the area infected. Intensive surveillance for early detection, and consequent plant removal, of new outbreaks is crucial for both successful eradication and containment at the regional scale, in addition to effective vector control. The assessment of impacts indicated that almond and Citrus spp. were at lower impact on yield compared to olive. Although the lowest impact was estimated for grapevine, and the highest for olive, this was based on several assumptions including that the assessment considered only Philaenus spumarius as a vector. If other xylem‐feeding insects act as vectors the impact could be different. Since the Scientific Opinion published in 2015, there are still no risk reduction options that can remove the bacterium from the plant in open field conditions. Short‐ and long‐range spread modelling showed that an early detection and rapid application of phytosanitary measures, consisting among others of plant removal and vector control, are essential to prevent further spread of the pathogen to new areas. Further data collection will allow a reduction in uncertainty and facilitate more tailored and effective control given the intraspecific diversity of X. fastidiosa and wide host range.Additional co-authors: EFSA Panel on Plant Health (PLH), Wopke van der Werf, Antonio Vicent Civera, Jonathan Yuen, Lucia Zappalà, Donato Boscia, Gianni Gilioli, Rodrigo Krugner, Alexander Mastin, Anna Simonetto, Joao Roberto Spotti Lopes, Steven White, José Cortinas Abrahantes, Alice Delbianco, Andrea Maiorano, Olaf Mosbach‐Schulz, Giuseppe Stancanelli, Michela Guzzo, Stephen Parnel

Commodity risk assessment of Ficus carica plants from Israel

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. This Scientific Opinion covers the plant health risks posed by the following commodities: (i) dormant and free of leaves 1-year-old bare rooted plants and (ii) free of leaves 1-year-old liners of Ficus carica imported from Israel, taking into account the available scientific information, including the technical information provided by Israel. The relevance of any pest for this opinion was based on evidence following defined criteria. Four EU quarantine pests, Euwallacea fornicatus, Hypothenemus leprieuri, Scirtothrips dorsalis and Spodoptera frugiperda, and 11 EU nonregulated pests fulfilled all relevant criteria and were selected for further evaluation. For these pests, the risk mitigation measures proposed in the technical dossier from Israel were evaluated separately for bare rooted plants and for liners, taking into account the possible limiting factors. For these pests, an expert judgement was given on the likelihood of pest freedom taking into consideration the risk mitigation measures acting on the pest, including uncertainties associated with the assessment. The estimated degree of pest freedom varied among the pests evaluated. Aonidiella orientalis and Russellaspis pustulans were the most frequently expected pests on the imported bare rooted plants, and Scirtothrips dorsalis on liners. The Expert Knowledge Elicitation indicated, with 95% certainty, that between 9,585 and 10,000 bare rooted plants per 10,000 would be free of Aonidiella orientalis and Russellaspis pustulans and between 9,456 and 10,000 liners per 10,000 would be free of Scirtothrips dorsalis

Commodity risk assessment of Juglans regia plants from Turkey

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. This Scientific Opinion covers the plant health risks posed by 2‐year‐old grafted bare rooted plants for planting of Juglans regia imported from Turkey, taking into account the available scientific information, including the technical information provided by Turkey. The relevance of any pest for this Opinion was based on evidence following defined criteria. Two EU quarantine pests, Anoplophora chinensis and Lopholeucaspis japonica, and three pests not regulated in the EU, two insects (Garella musculana, Euzophera semifuneralis) and one fungus (Lasiodiplodia pseudotheobromae), fulfilled all relevant criteria and were selected for further evaluation. For these pests, the risk mitigation measures proposed in the technical dossier from Turkey were evaluated by considering the possible limiting factors. For these pests, an expert judgement was given on the likelihood of pest freedom taking into consideration the risk mitigation measures acting on the pests, including uncertainties associated with the assessment. While the estimated degree of pest freedom varied among pests, Lasiodiplodia pseudotheobromae was the pest most frequently expected on the commodity. The expert knowledge elicitation indicated, with 95% certainty, that 9,554 or more grafted bare rooted plants per 10,000 will be free from Lasiodiplodia pseudotheobromae