Task planning and control synthesis for robotic manipulation in space applications

Space-based robotic systems for diagnosis, repair and assembly of systems will require new techniques of planning and manipulation to accomplish these complex tasks. Results of work in assembly task representation, discrete task planning, and control synthesis which provide a design environment for flexible assembly systems in manufacturing applications, and which extend to planning of manipulatiuon operations in unstructured environments are summarized. Assembly planning is carried out using the AND/OR graph representation which encompasses all possible partial orders of operations and may be used to plan assembly sequences. Discrete task planning uses the configuration map which facilitates search over a space of discrete operations parameters in sequential operations in order to achieve required goals in the space of bounded configuration sets

Mitochondrial Dynamics in the Drosophila Ovary Regulates Germ Stem Cell Number, Cell Fate, and Female Fertility

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (H2020-ERC-2017-STGGA 759853-StemCellHabitat), Wellcome Trust and Howard Hughes Medical Institute (HHMI-208581/Z/17/Z-Metabolic Reg SC fate), EMBO Installation grant (H2020-EMBO3311/2017/G2017), and by Fundação para a Ciência e Tecnologia (IF/01265/2014/CP1252/CT0004 and PD/BD/128003/2016 to MG).The fate and proliferative capacity of stem cells have been shown to strongly depend on their metabolic state. Mitochondria are the powerhouses of the cell being responsible for energy production via oxidative phosphorylation (OxPhos) as well as for several other metabolic pathways. Mitochondrial activity strongly depends on their structural organization, with their size and shape being regulated by mitochondrial fusion and fission, a process known as mitochondrial dynamics. However, the significance of mitochondrial dynamics in the regulation of stem cell metabolism and fate remains elusive. Here, we characterize the role of mitochondria morphology in female germ stem cells (GSCs) and in their more differentiated lineage. Mitochondria are particularly important in the female GSC lineage. Not only do they provide these cells with their energy requirements to generate the oocyte but they are also the only mitochondria pool to be inherited by the offspring. We show that the undifferentiated GSCs predominantly have fissed mitochondria, whereas more differentiated germ cells have more fused mitochondria. By reducing the levels of mitochondrial dynamics regulators, we show that both fused and fissed mitochondria are required for the maintenance of a stable GSC pool. Surprisingly, we found that disrupting mitochondrial dynamics in the germline also strongly affects nurse cells morphology, impairing egg chamber development and female fertility. Interestingly, reducing the levels of key enzymes in the Tricarboxylic Acid Cycle (TCA), known to cause OxPhos reduction, also affects GSC number. This defect in GSC self-renewal capacity indicates that at least basal levels of TCA/OxPhos are required in GSCs. Our findings show that mitochondrial dynamics is essential for female GSC maintenance and female fertility, and that mitochondria fusion and fission events are dynamically regulated during GSC differentiation, possibly to modulate their metabolic profile.publishersversionpublishe

On Selecting and Scheduling Assembly Plans Using Constraint Programming

This work presents the application of Constraint Programming to the problem of selecting and sequencing assembly operations. The set of all feasible assembly plans for a single product is represented using an And/Or graph. This representation embodies some of the constraints involved in the planning problem, such as precedence of tasks, and the constraints due to the completion of a correct assembly plan. The work is focused on the selection of tasks and their optimal ordering, taking into account their execution in a generic multi-robot system. In order to include all different constraints of the problem, the And/Or graph representation is extended, so that links between nodes corresponding to assembly tasks are added, taking into account the resource constraints. The resultant problem is mapped to a Constraint Satisfaction Problem (CSP), and is solved using Constraint Programming, a powerful programming paradigm that is increasingly used to model and solve many hard real-life problems

A Pomset-Based Model for Estimating Workcells' Setups in Assembly Sequence Planning

This paper presents a model based on pomsets (partially ordered multisets) for estimating the minimum number of setups in the workcells in Assembly Sequence Planning. This problem is focused through the minimization of the makespan (total assembly time) in a multirobot system. The planning model considers, apart from the durations and resources needed for the assembly tasks, the delays due to the setups in the workcells. An A* algorithm is used to meet the optimal solution. It uses the And/Or graph for the product to assemble, that corresponds to a compressed representation of all feasible assembly plans. Two basic admissible heuristic functions can be defined from relaxed models of the problem, considering the precedence constraints and the use of resources separately. The pomset-based model presented in this paper takes into account the precedence constraints in order to obtain a better estimation for the second heuristic function, so that the performance of the algorithm could be improved

Forage Legumes in Tropical Regions: Recent Advances and Future Challenges

Nitrogen input in tropical pastures increases forage and animal productivity. Forage legumes can fix atmospheric nitrogen and are the most economical way to add this nutrient to the soil. Our objective was to report the benefits of forage legumes in tropical pastures and possible strategies to implement different forage legumes. In tropical conditions, such as in Brazil, the use of forage legumes is still scarce. Even with low legume adoption on tropical pastures, forage legumes can provide ecosystem services. Increased animal productivity is the first ecosystem service provided by these legumes, mainly due to the addition of nitrogen that is typically the most limiting nutrient on tropical soils and yet the most important driver of plant growth and development. Legumes also provide an opportunity to increase nitrogen cycling in grassland, reducing grassland degradation. Pastures that include legumes have greater litter quality than grass monocultures, increasing soil organic matter at a faster rate. Legumes improve diet nutritive value and animal performance, resulting in reduced enteric methane emissions per unit of animal product. Additionally, legumes are generally associated with lower nitrous oxide emissions than N-fertilized grass swards and reduce the carbon footprint from the system due to nitrogen manufacture, transport, storage, and application. However, the greatest challenge in tropical pastures is to increase the adoption of forage legumes. It is necessary to understand the role of different legumes in the pasture environment. Some legumes have high herbage accumulation and biological nitrogen fixation potential, but they have low canopy stability; nonetheless, they could be used on short-lived pastures as well as integrated crop-livestock systems. When the objective is to achieve grass-legume stability in mixed pastures, it is necessary to use clonal propagation legumes and provide appropriate defoliation management to minimize light competition among plant communities

How Similar Are They?

Funding: Fundação para a Ciência e Tecnologia (FCT) Grant PTDC/BIABID/29663/2017 to DC, and ERC (H2020-ERC-2017-STG-GA 759853-StemCellHabitat); Wellcome Trust and Howard Hughes Medical Institute (HHMI-208581/Z/17/Z-Metabolic Reg SC fate); EMBO (H2020-EMBO-3311/2017/G2017), and FCT grant IF/01265/2014/CP1252/CT0004 to CH.Proneural genes were initially identified in Drosophila, where pioneer work on these important regulators of neural development was performed, and from which the term proneural function was coined. Subsequently, their counterparts in vertebrates were identified, and their function in neural development extensively characterized. The function of proneural transcription factors in flies and vertebrates is, however, very distinct. In flies, proneural genes play an early role in neural induction, by endowing neural competence to ectodermal cells. In contrast, vertebrate proneural genes are expressed only after neural specification, in neural stem and progenitor cells, where they play key regulatory functions in quiescence, proliferation, and neuronal differentiation. An exception to this scenario is the Drosophila proneural gene asense, which has a late onset of expression in neural stem cells of the developing embryo and larvae, similar to its vertebrate counterparts. Although the role of Asense remains poorly investigated, its expression pattern is suggestive of functions more in line with those of vertebrate proneural genes. Here, we revise our current understanding of the multiple activities of Asense and of its closest vertebrate homologue Ascl1 in neural stem/progenitor cell biology, and discuss possible parallels between the two transcription factors in neurogenesis regulation.publishersversionpublishe

Azorean Bryophytes : a preliminary review of rarity patterns

Proceedings of the Symposium "Darwin's Mistake and what we are doing to correct it". Ponta Delgada, 19-22 September, 2009.Os briófitos podem ser tão raros e estar tão ameaçados como os demais organismos do planeta, apesar de o seu pequeno tamanho, cores discretas e difícil identificação no campo poderem mascarar o seu verdadeiro estatuto de conservação. De facto, é reconhecido que cerca de um quarto de todos os briófitos da Europa estão efectiva ou potencialmente ameaçados. O primeiro “Livro Vermelho dos Briófitos da Europa” foi produzido em 1995, amplamente baseado em listas vermelhas nacionais e no trabalho de uma vasta equipa de briólogos que avaliaram o estatuto de conservação para as espécies Europeias. A classificação de briófitos em listas vermelhas tem contribuído para aumentar a sensibilidade dos gestores para este grupo de organismos e alguns esforços têm sido desenvolvidos na Europa, para preservar locais tendo como característica o seu interesse briológico. Consequentemente, uma lista vermelha para os briófitos dos Açores pode auxiliar os gestores regionais a identificar espécies particularmente ameaçadas, tornando-se o primeiro passo para assegurar a sua protecção. Neste artigo usamos uma adaptação dos trabalhos de Deborah Rabinowitz (1981), que criou uma tipologia para desocultar e avaliar várias formas de raridade, utilizando três variáveis: Distribuição Geográfica, Abundância e Especificidade do Habitat. Todas as 480 espécies e subespécies dos Açores foram investigadas: 215 taxa não tinham informação suficiente para ser analisados (deficientes em dados), 121 não foram consideradas raros e 144 briófitos (1 antocerota, 56 hepáticas e 87 musgos) foram considerados raros pelo menos num dos parâmetros considerados. Os benefícios e limitações desta metodologia são brevemente discutidos. São propostas algumas sugestões práticas para melhorar a estratégia de conservação dos briófitos seleccionados.ABSTRACT: Bryophytes are not exempt of rarity and threat, although their small size, mute colours and difficult field identification may mask their true conservation status. Actually, it is known that a quarter of all European bryophytes are under actual or potential threat. The first Red Data Book for European Bryophytes was produced in 1995, largely based on national red lists and on the work of a vast team of bryologists who assessed the conservation status of each European species. The red listing of bryophytes has undoubtedly contributed to increase the awareness of planners to this group of organisms, and several efforts have been made, through Europe, to preserve sites based on their bryological interest. Accordingly, a specific Red List for the Azorean Bryophytes may help regional managers to identify particularly endangered species, thus allowing for the creation of measures to improve their preservation. In this paper we have used an adaptation of the works of Deborah Rabinowitz (1981), who created a typology to access different forms of rarity, using three variables: Geographical Distribution, Abundance and Habitat Specificity. All the 480 species and subspecies known to occur in the Azores were surveyed; of these, 215 species lacked sufficient data to be analyzed (data deficient), 121 were not considered rare and 144 (1 hornworts, 56 liverworts and 87 mosses) were considered rare, at least in one of the three parameters considered. The benefits and limitations of the methodology are briefly discussed. Several practical suggestions are proposed in order to enhance the conservation of selected bryophyte species

Legume and Nitrogen Fertilization Affect Animal Performance and Enteric Methane Emission of Nellore Heifers

Methane emission from livestock operation is an important source of greenhouse gas and contributes to global warming. Forage legume secondary compounds may mitigate methane emissions by reducing methanogenic population in the rumen. This study evaluated animal performance and methane emission from beef cattle grazing either a mixed pasture [Brachiaria brizantha cv. Marandu (palisadegrass) and Arachis pintoi (forage peanut) cv. BRS Mandobi] or a palisadegrass monoculture with or without nitrogen (N) fertilisation. A 2.5-yr continuous stocking experiment was carried out in southeast Brazil, on a randomized complete block design with three treatments and four replicates. Two Nellore heifers were used as tester animals and additional put-and-takes were used to keep canopy height at 20-25 cm. The treatments comprised three pasture types: 1) palisadegrass-forage peanut mixed pasture (GRASS+LEGUME); 2) palisadegrass + 150 kg N/ha/year (GRASS+N); 3) palisadegrass without N fertilization (GRASS). Response variables included average daily gain (ADG), forage intake, and methane emission. Methane emission was estimated by the sulphur hexafluoride (SF6) tracer technique. There was no difference between grazing systems for the ADG (P = 0.439) and DMI (P = 0.394; averages of 0.433 kg/d and 2.10 %BW/d, respectively). In the GRASS+LEGUME, there was a decrease of 11.7% in methane emission per animal (148 vs. 170 and 165 g/day for GRASS+N and GRASS, respectively; P = 0.001). Grazing systems including legume reduced methane emission per unit of ADG (365 vs. 428 and 398 g/kg for GRASS and GRASS+N, respectively; P = 0.061) and per carcass gain (656 vs. 800 g of methane/kg carcass for GRASS; P = 0.022). Intake of condensed tannins was greater for GRASS+LEGUME (0.61 vs. 0.17 %BW/d, P \u3c 0.001). Forage peanut decreased enteric methane emission intensity, reducing carbon footprint of livestock systems in Southeast Brazil

Short-Term Soil Organic Matter and Carbon Responses to Contrasting Grazing Intensities in Integrated Crop-Livestock Systems

Combining integrated crop-livestock systems under no-till management may improve soil organic matter (SOM) build up and improve soil C sequestration. Grazing cover crops appears as a possibility to combine crops and livestock in a farm system. Further SOM and soil C increase can be achieved by adding perennial grasses into crop rotations. However, the effect of grazing intensity in such systems are not fully understood. This 2-yr study investigated short-term effects of cropping system [winter cover crops-summer cotton (Gossypium hirsutum L.) and winter cover crops-summer bahiagrass (Paspalum notatum Flüggé) rotations], grazing intensity (no grazing, heavy, moderate, and light grazing), and N fertilization (34 and 90 kg N ha-1 ), on OM and soil C of the soil-surface (0-15 cm) and deep-soil (0-90 cm) under no-till. Preliminary results indicate that treatments containing bahiagrass improved SOM in 1.5 g kg-1 compared to winter grazing on cover crops-cotton systems (P = 0.017). There were no differences among treatments for soil total C stock (15.4 Mg ha-1) and particulate OM-C (4.8 Mg ha-1) at the 15-cm depth (P \u3e 0.1). Carbon concentration increased from 8.0 to 12.6 g kg-1 as aggregate fraction decreased from 250 – 2000 to \u3c 53 µm (P \u3c 0.001). Nonetheless, C stock was not affected by aggregate fraction, with each fraction containing 3.8 Mg C ha-1, on average. Carbon stocks from 0-15, 15-30, 30-60, and 60-90-cm depths did not differ among treatments (P = 0.743), totalizing 30.4 Mg C ha-1 in the soil profile. Long-term studies are necessary to better understand the role of cropping system and grazing intensities on soil OM and C responses on surface and deep soil

New insights on mechanisms of sulfonamide bio-transformation by environmental bacteria

info:eu-repo/semantics/publishedVersio