How to Blend a Robot within a Group of Zebrafish: Achieving Social Acceptance through Real-time Calibration of a Multi-level Behavioural Model

We have previously shown how to socially integrate a fish robot into a group of zebrafish thanks to biomimetic behavioural models. The models have to be calibrated on experimental data to present correct behavioural features. This calibration is essential to enhance the social integration of the robot into the group. When calibrated, the behavioural model of fish behaviour is implemented to drive a robot with closed-loop control of social interactions into a group of zebrafish. This approach can be useful to form mixed-groups, and study animal individual and collective behaviour by using biomimetic autonomous robots capable of responding to the animals in long-standing experiments. Here, we show a methodology for continuous real-time calibration and refinement of multi-level behavioural model. The real-time calibration, by an evolutionary algorithm, is based on simulation of the model to correspond to the observed fish behaviour in real-time. The calibrated model is updated on the robot and tested during the experiments. This method allows to cope with changes of dynamics in fish behaviour. Moreover, each fish presents individual behavioural differences. Thus, each trial is done with naive fish groups that display behavioural variability. This real-time calibration methodology can optimise the robot behaviours during the experiments. Our implementation of this methodology runs on three different computers that perform individual tracking, data-analysis, multi-objective evolutionary algorithms, simulation of the fish robot and adaptation of the robot behavioural models, all in real-time.Comment: 9 pages, 3 figure

The Ontogenetic Osteohistology of Tenontosaurus tilletti

Tenontosaurus tilletti is an ornithopod dinosaur known from the Early Cretaceous (Aptian-Albian) Cloverly and Antlers formations of the Western United States. It is represented by a large number of specimens spanning a number of ontogenetic stages, and these specimens have been collected across a wide geographic range (from central Montana to southern Oklahoma). Here I describe the long bone histology of T. tilletti and discuss histological variation at the individual, ontogenetic and geographic levels. The ontogenetic pattern of bone histology in T. tilletti is similar to that of other dinosaurs, reflecting extremely rapid growth early in life, and sustained rapid growth through sub-adult ontogeny. But unlike other iguanodontians, this dinosaur shows an extended multi-year period of slow growth as skeletal maturity approached. Evidence of termination of growth (e.g., an external fundamental system) is observed in only the largest individuals, although other histological signals in only slightly smaller specimens suggest a substantial slowing of growth later in life. Histological differences in the amount of remodeling and the number of lines of arrested growth varied among elements within individuals, but bone histology was conservative across sampled individuals of the species, despite known paleoenvironmental differences between the Antlers and Cloverly formations. The bone histology of T. tilletti indicates a much slower growth trajectory than observed for other iguanodontians (e.g., hadrosaurids), suggesting that those taxa reached much larger sizes than Tenontosaurus in a shorter time

Drilling their own graves:How the European oil and gas supermajors avoid sustainability tensions through mythmaking

This study explores how paradoxical tensions between economic growth and environmental protection are avoided through organizational mythmaking. By examining the European oil and gas supermajors’ ‘‘CEOspeak’’ about climate change, we show how mythmaking facilitates the disregarding, diverting, and/or displacing of sustainability tensions. In doing so, our findings further illustrate how certain defensive responses are employed: (1) regression, or retreating to the comforts of past familiarities, (2) fantasy, or escaping the harsh reality that fossil fuels and climate change are indeed irreconcilable, and (3) projecting, or shifting blame to external actors for failing to address climate change. By highlighting the discursive effects of enacting these responses, we illustrate how the European oil and gas supermajors self-determine their inability to substantively address the complexities of climate change. We thus argue that defensive responses are not merely a form of mismanagement as the paradox and corporate sustainability literature commonly suggests, but a strategic resource that poses serious ethical concerns given the imminent danger of issues such as climate change

Cortical histomorphometry of the human humerus during ontogeny

Modeling and remodeling are two key determinants of human skeletal growth though little is known about the histomorphometry of cortical bone during ontogeny. In this study we examined the density and geometric properties of primary and secondary osteons (osteon area and diameter, vascular canal area and diameter) in sub-periosteal cortical bone from the human humerus (n=84) between birth and age 18 years. Sections were removed from the anterior midshaft aspect of humeri from skeletons. Age-at-death was reconstructed using standard osteological techniques. Analyses revealed significant correlation between the histomorphometric variables and age. Higher densities of primary osteons occurred between infancy and seven years of age but were almost completely replaced by secondary osteons after 14 years of age. The geometry of primary osteons was less clearly related to age. Secondary osteons were visible after two years of age, and reached their greatest densities in the oldest individuals. Osteon size was positively but weakly influenced by age. Our data implies that modeling and remodeling are age dependent processes that vary markedly from birth to adulthood in the human humerus

Bone histology provides insights into the life history mechanisms underlying dwarfing in hipparionins

Size shifts may be a by-product of alterations in life history traits driven by natural selection. Although this approach has been proposed for islands, it has not yet been explored in continental faunas. The trends towards size decrease experienced by some hipparionins constitute a good case study for the application of a life history framework to understand the size shifts on the continent. Here, we analysed bone microstructure to reconstruct the growth of some different-sized hipparionins from Greece and Spain. The two dwarfed lineages studied show different growth strategies. The Greek hipparions ceased growth early at a small size thus advancing maturity, whilst the slower-growing Spanish hipparion matured later at a small size. Based on predictive life history models, we suggest that high adult mortality was the likely selective force behind early maturity and associated size decrease in the Greek lineage. Conversely, we infer that resource limitation accompanied by high juvenile mortality triggered decrease in growth rate and a relative late maturity in the Spanish lineage. Our results provide evidence that different selective pressures can precipitate different changes in life history that lead to similar size shifts

Reducing Radiation Dose at Chest CT: Comparison Among Model-based Type Iterative Reconstruction, Hybrid Iterative Reconstruction, and Filtered Back Projection.

The study aimed to evaluate the performances of two iterative reconstruction (IR) algorithms and of filtered back projection (FBP) when using reduced-dose chest computed tomography (RDCT) compared to standard-of-care CT. An institutional review board approval was obtained. Thirty-six patients with hematologic malignancies referred for a control chest CT of a known lung disease were prospectively enrolled. Patients underwent standard-of-care scan reconstructed with hybrid IR, followed by an RDCT reconstructed with FBP, hybrid IR, and iterative model reconstruction. Objective and subjective quality measurements, lesion detectability, and evolution assessment on RDCT were recorded. For RDCT, the CTDIvol (volumetric computed tomography dose index) was 0.43 mGy⋅cm for all patients, and the median [interquartile range] effective dose was 0.22 mSv [0.22-0.24]; corresponding measurements for standard-of-care scan were 3.4 mGy [3.1-3.9] and 1.8 mSv [1.6-2.0]. Noise significantly decreased from FBP to hybrid IR and from hybrid IR to iterative model reconstruction on RDCT, whereas lesion conspicuity and diagnostic confidence increased. Accurate evolution assessment was obtained in all cases with IR. Emphysema identification was higher with iterative model reconstruction. Although iterative model reconstruction offered better diagnostic confidence and emphysema detection, both IR algorithms allowed an accurate evolution assessment with an effective dose of 0.22 mSv

Sustained response to salvage therapy for dabrafenib-resistant metastatic Langerhans cell sarcoma

International audienceLangerhans cell sarcoma (LCS) is a rare high-grade malignancy of Langerhans cells involving the lymphatic system and extranodal sites [1.]. Patients with multiorgan involvement have a poor prognosis and a high mortality rate despite treatment with several chemotherapeutic regimens [1.]. LCS tumor cells may harbor the BRAFV600E mutation [2.], which suggests that these patients may benefit from BRAF inhibitors (BRAFi). We recently reported the marked improvement of a 58-year-old male patient with metastatic BRAFV600E-mutated LCS following treatment with the BRAFi dabrafenib, but unfortunately the disease recurred after 6 months of treatment [3.]. Here, we describe the subsequent impressive and sustained response achieved using a combination of the BRAFi vemurafenib and the MAPK kinase inhibitor (MEKi) cobimetinib.The general condition of this patient had deteriorated at the time of LCS recurrence. The patient had an Eastern Cooperative Oncology Group (ECOG) performance status of 4, a 39°C fever and intense biological inflammatory syndrome (CRP: 328 mg/l). At this time, lung computed tomography (CT) showed progression of LCS as a large left mediastinal and pulmonary tumor with lymphangitic carcinomatosis and concurrent left axillary adenopathy (Figure 1A). We obtained informed consent before initiating vemurafenib (960 mg twice daily) and cobimetinib (60 mg once daily for 21 days per 28-day cycle). The patient dramatically improved and became afebrile on day 3 of treatment. After 3 months, the patient's ECOG performance status was 1. The mediastinal tumor completely resolved, and the pulmonary and axillary lesions decreased by 80% compared with baseline (Figure 1A). The patient had a partial response according to the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. After 12 months of treatment, he was stable and maintained a radiological response. There was minimal fluorodeoxyglucose (18-FDG) uptake, as observed by positron emission tomography (PET)-CT, in the pulmonary and axillary lesions, confirming the persistent control of the disease (Figure 1A). The treatment was well tolerated, with the exception of a cutaneous rash that spontaneously resolved. The plasma concentrations of cobimetinib and vemurafenib were measured monthly at steady state (day 15 of each cycle) and reached the median values (range) of 72.7 ng/ml (47–95.4) and 39.8 µg/ml (32.1–49.8), respectively, which are consistent with the results of previous pharmacokinetic studies. The BRAFV600E mutation levels were monitored in the patient's plasma before and after treatment using the Enhanced-Ice-Cold-PCR technique, as previously described [4.]. The BRAFV600E mutation level (percent mutant allele fraction) decreased from 2.3% at the time of LCS recurrence to values below the sensitivity threshold (0.5%) at day 60, which was maintained throughout treatment (Figure 1B)