Study of the doubly charmed tetraquark T+cc

Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D0D0π+ mass spectrum just below the D*+D0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T+cc tetraquark with a quark content of ccu⎯⎯⎯d⎯⎯⎯ and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*+ mesons is consistent with the observed D0π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector T+cc state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T+cc state. In addition, an unexpected dependence of the production rate on track multiplicity is observed

Est-il possible d'estimer précisément la richesse spécifique de grands quadrats? Cas d'étude sur des données de calibration entre observateurs

International audienceThe number of species (species richness) is certainly the most widely used descriptor of plant diversity. However, estimating richness is a difficult task because plant censuses are prone to overlooking and identification errors that may lead to spurious interpretations. We used calibration data from the French ICP-level II plots (RENECOFOR) to assess the magnitude of the two kinds of errors in large forest plots. Eleven teams of professional botanists recorded all plants on the same eight 100-m2 plots in 2004 (four plots, eights teams) and 2005 (four plots, nine teams including six from 2004), first independently and then consensually. On average, 15.5% of the shrubs and trees above 2 m were overlooked and 2.3% not identified at the species level or misidentified. On average, 19.2% of the plant species below 2 m in height were overlooked and 5.3% were misidentified and 1.3% were misidentified at the genus level (especially bryophytes). The overlooking rate also varied with plant species, morphological type, plot and team. It was higher when only one botanist made the census. It rapidly decreased with species cover and increased with plot species richness, the recording time of the census in the tree layer and the number of the censuses carried out during the day in the ground layer. Familiarity of the team with the local flora reduced the risk of overlooking and identification errors, whereas training had little impact. Differences in species richness (over space or time) in large plots should be cautiously interpreted, especially when several botanists participate in the survey. In particular, the quality of the data needs to be evaluated using calibration training and, if necessary, may be improved by involving more experienced botanists working in teams and by fixing a minimum recording time

Uso de volumosos conservados na alimentação de equinos Use of conserved roughage in the horse feeding

Revisão de artigos sobre características e uso de forragens conservadas na alimentação de equinos, considerando o bem estar animal e ressaltando a necessidade de integrar a atual tecnologia do uso, fisiologia, manejo e nutrição animal. Um ponto básico e critico no manejo alimentar de equinos é a disponibilidade de forragens de alta qualidade para uso como pastagens, ou forragens conservadas na forma de fenos e silagens. Os mais tecnificados sistemas de produção animal adotaram o feno para alimentação e este é o motivo pelo qual grande parte dos artigos científicos relativos à nutrição de equinos usou o feno como volumoso. Silagens são adotadas em alguns sistemas, porém poucos artigos técnicos estão disponíveis avaliando seu uso na nutrição de equinos. Devido às características anatômicas e fisiológicas, o equino deve receber grandes quantidades de forragem e a taxa de fornecimento deve permitir a seletividade da captura e fácil ingestão da forragem. Para qualquer volumoso, o perfil nutricional deste é diferente quando oferecido na forma de pastagem ou forragem conservada, situação atribuída a seletividade e individualidade animal bem como a variação nas partes da planta. Paralelamente com o conhecimento da composição nutricional e manejo de conservação de forragem, especial atenção deve ser dada as condições ambientais de alojamento e restrição de movimentos dos animais. O planejamento de atividade física para o equino conjuntamente com o manejo adequado ajuda a prevenir problemas que afetam animais que não tem acesso a pastagem. Os fenos, silagens e pré-secados, usados quando a pastagem não é disponível, divide com o concentrado o maior número de casos de problemas de saúde. Cólica, acidose, laminite, consumo de palha e madeira estão associados a deficiências nutricionais, desconsiderando erros humanos e condições ambientais desapropriadas. Informações técnicas para melhor entendimento sobre o consumo animal em qualidade, quantidade e/ou a forma que o alimento é fornecido, vem sendo responsável pelo desempenho positivo e bom manejo de equinos mantidos em sistemas que o privam de acesso a pastos e atividades físicas.<br>This text revised some papers in literature about characteristics and use of conserved forages for horse feeding, considering animal behavior and outstanding the need of programs that could integrate the current knowledge of use, physiology, management and animal nutrition. A basic and critical nutritional condition for equine management is the availability of high quality forage for use as pasture or conserved as hay or silage. Most professional horse production systems adopt hay for animal feeding and this is why most available scientific papers regarding horse nutrition uses hay as roughage. Silages are adopted in some systems, but a smaller number of studies are available in technical literature evaluating his use in horse nutrition. Due to their anatomic and physiological characteristics, horses should be given high quality pastures and stocking rates must allow selectivity in forage capture and easy ingestion. For any forage, the nutritional profile is different if offered to animals used as pasture or conserved, due selectivity, plants part and variation among horses. Besides the analytical results of feeds and conservation processes adopted, special attention should be given to the environmental conditions of animal kept in stables or with restricted movements. A physical activity plan for horses and adherence to appropriate routines help preventing problems that affect animals without access to pasture. The hays, silages and haylages used as substitutes when pasture is not available, share with concentrates the highest position as causes of health problems. Colic, acidosis, laminitis, straw and wood consumption are associated to nutritional deficiencies, without considering human mistakes and inappropriate environmental conditions. Technical information for better understanding of animal consumption in quality, quantity or the way food is offered, has been responsible for the positive performance and good management in systems that deprive their access to pastures or physical activities