On fitting planetary systems in counter-revolving configurations

In Gayon & Bois (2008) and Gayon etal (2009), (i) we studied the theoretical feasibility and efficiency of retrograde mean motion resonances (i.e. two planets are both in orbital resonance and in counter-revolving configuration), (ii) we showed that retrograde resonances can generate interesting mechanisms of stability, and (iii) we obtained a dynamical fit involving a counter-revolving configuration that is consistent with the observations of the HD73526 planetary system. In the present paper, we present and analyze data reductions assuming counter-revolving configurations for eight compact multi-planetary systems detected through the radial velocity method. In each case, we select the best fit leading to a dynamically stable solution. The resulting data reductions obtained in rms and chi values for counter-revolving configurations are of the same order, and sometimes slightly better, than for prograde configurations. In the end, these fits tend to show that, over the eight studied multi-planetary systems, six of them could be regulated by a mechanism involving a counter-revolving configuration.Comment: 4 pages, 1 figure, 2 tables, accepted for publication in MNRAS letters (August 10, 2009

Évolution et hasard

Dans la théorie contemporaine de l’évolution, trois sens classiques de la notion de hasard interviennent : la notion ordinaire de chance, la notion probabiliste de l’aléatoire, et la notion épistémologique de contingence relativement à un système théorique. Ces trois notions suffisent à définir le statut du hasard aux principaux niveaux du processus évolutif où l’on invoque communément des effets fortuits : mutations, dérive génétique, révolutions génétiques, changements écologiques, macroévolution. On se demande enfin si les divers sens du hasard rencontrés dans cette étude peuvent être ramenés à l’unité, et s’ils renvoient à un hasard subjectif (ou « épistémique ») ou à un hasard objectif.In the contemporary theory of evolution, three classical meanings of the notion of chance come into play : the ordinary meaning of chance, the probabilistic notion of randomness, and the epistemological notion of contingency with reference to a theoretical system. These three notions are sufficient in order to define the status of chance on the principal levels of the evolutive process where fortuitous effects are commonly invoked : mutations, genetic deviations, genetic revolutions, ecological changes, macroevolution. The question is raised, finally, whether the diverse meanings of chance considered in the present study may be brought to one, and whether they refer to a subjective (or “epistemic”) form of chance or to an objective chance

Economic Natural Selection: What Concept of Selection?

International audienceThe article examines two cases of adoption of evolutionary ways of thinking by modern economists: Nelson and Winter's (Evolutionary Theory of Economic Change, 1982), and evolutionary game theory (1990s and after). In both cases, the authors explicitly refer to natural selection in an economic context. I show that natural selection is taken in two different senses, which correspond to two general conceptions of the principle of natural selection, one of which contains reproduction and heredity as key elements, whereas the other does not

Developing a collaborative project on higher education pedagogy: The institutional, organizational, and community identity dimensions of student staff partnerships

This case study presents an ambitious student-staff partnership project at University College London (UCL) to publish a collaborative book on higher education pedagogy. Over two-and-a-half years, a total of 86 students and staff contributed to the project, which sought to provide educators with a new type of scholarly material under the unifying theme of connecting research and teaching. Multiple layers of student-staff partnership were interwoven throughout the project; this case study contextualizes these layers against three dimensions: institutional, organizational, and community identity. Central to the project was our distinctive approach to engaging with Graduate Teaching Assistants (GTAs) and their crucial role in bringing the three dimensions together. As such, the project represents a model of enhanced student-staff partnership that has the capacity to empower students and break down educational silos to form new, multi-specialty learning communities.</jats:p

Edible leafy vegetables from West Africa (Guinea-Bissau): consumption, trade and food potential

Wild Edible Plants are common in the diet of rural communities of sub-Saharan Africa. In Guinea-Bissau, West Africa, wild plant resources are widely used in human diet, but very few studies have addressed them. The aim of this study is to reveal: (1) the wild and semi-cultivated leafy vegetables consumed in Guinea-Bissau; and (2) the nutritional composition of those plants traded at the largest country market in Bissau. Our results revealed that 24 native or naturalized species with edible leaves are currently consumed by Guinea-Bissau population. Five of them were found at the market: dried leaves of Adansonia digitata, Bombax costatum and Sesamum radiatum, and fresh leaves and shoots of Amaranthus hybridus and Hibiscus sabdari a. The analysis of the nutritional properties revealed that leaves contain a significant amount of protein (10.1–21.0 g/100 g, dry basis), high values of macronutrients and micronutrients, as well as of phenolic compounds (13.1–40.3 mg GAE/g) and a considerable antioxidant capacity (DPPH 111.5–681.9 mg Eq Trolox). Although price and availability vary among the leafy vegetables analyzed, these traditional foods appear to be a good dietary component that can contribute to food security in Guinea-Bissau and in other West African countries, as these species are widely distributed in this regioninfo:eu-repo/semantics/publishedVersio

Enzymatic cybernetics: An unpublished work by Jacques Monod

International audienceIn 1959, Jacques Monod wrote a manuscript entitled Cybernétique enzymatique [Enzymatic cybernetics]. Never published, this unpublished manuscript presents a synthesis of how Monod interpreted enzymatic adaptation just before the publication of the famous papers of the 1960s on the operon. In addition, Monod offers an example of a philosophy of biology immersed in scientific investigation. Monod's philosophical thoughts are classified into two categories, methodological and ontological. On the methodological side, Monod explicitly hints at his preferences regarding the scientific method in general: hypothetical-deductive method, and use of theoretical models. He also makes heuristic proposals regarding molecular biology: the need to analyse the phenomena in question at the level of individual cells, and the dual aspect of all biological explanation, functional and evolutionary. Ontological issues deal with the notions of information and genetic determinism, “cellular memory”, the irrelevance of the notion of “living matter”, and the usefulness of a cybernetic comprehension of molecular biology

Mineral composition through soil-wine system of portuguese vineyards and its potential for wine traceability

The control of geographic origin is one of a highest priority issue regarding traceability and wine authenticity. The current study aimed to examine whether elemental composition can be used for the discrimination of wines according to geographical origin, taking into account the effects of soil, winemaking process, and year of production. The elemental composition of soils, grapes, musts, and wines from three DO (Designations of Origin) and for two vintage years was determined by using the ICP-MS semi-quantitative method, followed by multivariate statistical analysis. The elemental composition of soils varied according to geological formations, and for some elements, the variation due to soil provenance was also observed in musts and wines. Li, Mn, Sr and rare-earth elements (REE) allowed wine discrimination according to vineyard. Results evidenced the influence of winemaking processes and of vintage year on the wine’s elemental composition. The mineral composition pattern is transferred through the soil-wine system, and differences observed for soils are reflected in grape musts and wines, but not for all elements. Results suggest that winemaking processes and vintage year should be taken into account for the use of elemental composition as a tool for wine traceability. Therefore, understanding the evolution of mineral pattern composition from soil to wine, and how it is influenced by the climatic year, is indispensable for traceability purposesinfo:eu-repo/semantics/publishedVersio

Unitary and analytic model of nucleon EM structure, the puzzle with JLab proton polarization data and new insight into proton charge distribution

The Unitary and analytic model of nucleon electromagnetic structure, describing all existing nucleon form factor data, is briefly reviewed. Then in the framework of this model the problem of inconsistency of older proton electric form factor data in space-like region (obtained from $e^{-}p$ process by the Rosenbluth technique) with recent Jefferson Lab data on the ratio $G_{Ep}(t)/G_{Mp}(t)$ (measured in precise polarization $\overrightarrow{e}^{-}p\to e^{-}\overrightarrow{p}$ experiment) is suggested to be solved in favour of the latter data which, however, unlike older data cause an existence of the form factor zero, i.e. a difraction minimum in $|G_{Ep}(t)|$ around $t=-Q^{2}=-13$GeV$^{2}$. The new behaviour of $G_{Ep}(t)$ with the zero gives modified proton charge distribution with enlarged value of the mean square charge radius.Comment: 9 pages, 11 eps figures. Talk presented at the workshop on Lepton Scattering and the Structure of Hadrons and Nuclei, Erice (Italy), September 200

The suitability of visual taphonomic methods for digital photographs: An experimental approach with pig carcasses in a tropical climate

In the context of increased scrutiny of the methods in forensic sciences, it is essential to ensure that the approaches used in forensic taphonomy to measure decomposition and estimate the postmortem interval are underpinned by robust evidence-based data. Digital photographs are an important source of documentation in forensic taphonomic investigations but the suitability of the current approaches for photographs, rather than real-time remains, is poorly studied which can undermine accurate forensic conclusions. The present study aimed to investigate the suitability of 2D colour digital photographs for evaluating decomposition of exposed human analogues (Sus scrofa domesticus) in a tropical savanna environment (Hawaii), using two published scoring methods; Megyesi et al., 2005 and Keough et al., 2017. It was found that there were significant differences between the real-time and photograph decomposition scores when the Megyesi et al. method was used. However, the Keough et al. method applied to photographs reflected real-time decomposition more closely and thus appears more suitable to evaluate pig decomposition from 2D photographs. The findings indicate that the type of scoring method used has a significant impact on the ability to accurately evaluate the decomposition of exposed pig carcasses from photographs. It was further identified that photographic taphonomic analysis can reach high inter-observer reproducibility. These novel findings are of significant importance for the forensic sciences as they highlight the potential for high quality photograph coverage to provide useful complementary information for the forensic taphonomic investigation. New recommendations to develop robust transparent approaches adapted to photographs in forensic taphonomy are suggested based on these findings

Dynamical stability analysis of the HD202206 system and constraints to the planetary orbits

Long-term precise Doppler measurements with the CORALIE spectrograph revealed the presence of two massive companions to the solar-type star HD202206. Although the three-body fit of the system is unstable, it was shown that a 5:1 mean motion resonance exists close to the best fit, where the system is stable. We present here an extensive dynamical study of the HD202206 system aiming at constraining the inclinations of the two known companions, from which we derive possible ranges of value for the companion masses. We study the long term stability of the system in a small neighborhood of the best fit using Laskar's frequency map analysis. We also introduce a numerical method based on frequency analysis to determine the center of libration mode inside a mean motion resonance. We find that acceptable coplanar configurations are limited to inclinations to the line of sight between 30 and 90 degrees. This limits the masses of both companions to roughly twice the minimum. Non coplanar configurations are possible for a wide range of mutual inclinations from 0 to 90 degrees, although $\Delta\Omega = 0 [\pi]$ configurations seem to be favored. We also confirm the 5:1 mean motion resonance to be most likely. In the coplanar edge-on case, we provide a very good stable solution in the resonance, whose $\chi^2$ does not differ significantly from the best fit. Using our method to determine the center of libration, we further refine this solution to obtain an orbit with a very low amplitude of libration, as we expect dissipative effects to have dampened the libration.Comment: 14 pages, 18 figure