Palm oil yield potential of oil palm (Elaeis guineensis) seeds developed in a network by Cirad and its partners

Over the last decade, there was very strong growth in the demand for vegetable oils and fats (+ 4.6% per year) and the oils extracted from oil palm fruits greatly contributed to satisfying those needs. Food demand continues to increase, as do traditional uses (cosmetics and oleo chemistry). A new demand for use as bio fuel also needs to be taken into account (1% of current consumption). For oil palm, high-yielding planting material that is as resistant as possible to diseases will be part of the answer proposed by breeders. The breeding scheme primarily involves a reciprocal recurrent selection scheme (RRS) which has been adapted to the biological constraints of the oil palm. The RRS recommended by CIRAD uses, in the form of hybrids, the heterosis effect obtained by crossing origins with complementary characteristics (group A) x (group B). It is also possible to include pedigree selection phases (A self or B self), which cannot really be considered as part of RRS, but the two strategies are complementary. In the oil palm, the general combining ability (GCA) for yield of a parent can only be known by assessing the value of the families it generates. However, some parental traits are heritable enough for it to be efficient to select them: vertical growth, mesocarp/fruit percentage, oil/mesocarp and the number of bunches produced. In order to assess the parental combining ability, we propose a scheme that makes it possible to test all family and each parent. Such a design makes it possible to evaluate the value of all the crosses by removing the inherent trial effect, and the planting year effect. It makes it possible to compare all the parents used in the design with each other. The share of variability explained by an additive model has been calculated. As an example, the Aek Loba design is described. Our study focuses on the mature period for the first 17 trials that have been observed up to 8 years (254 crosses, 114 parents in group A, and 112 in group B). At the progeny level, when selection is strong (8%) the gain recorded for oil production in the mature phase is slightly over 14%. That gain is obtained in an almost balanced way through progress in the extraction rate (+6.5%) and in FFB production (+7.2%). The average contribution of the best parents parent for oil production in the mature phase is around + 700 kg/ha/year. A cross carried out between two good parents leads to a gain of 1 400 kg/ha/year of oil. Some parents provide a significant gain, of more than 3 points, for the extraction rate (i.e. around +12% if the OER increases from 26% to 29%). The R2 between the observed values and the predicted values is 0.9: a purely additive model explains a very large share of the variability observed. Genetic gain will be maximum if we select parents for their GCA: even a moderate selection pressure (16%) leads to substantial genetic progress. In this case, the expected gains are 8% for the extraction rate, more than 9% for FFB production and 17 to 18% for palm oil production. (Résumé d'auteur

Shape in an Atom of Space: Exploring quantum geometry phenomenology

A phenomenology for the deep spatial geometry of loop quantum gravity is introduced. In the context of a simple model, an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used to develop a model of angular corrections to local, continuum flat-space 3-geometries. The physical effects involve neither breaking of local Lorentz invariance nor Planck scale suppression, but rather reply on only the combinatorics of SU(2) recoupling. Bhabha scattering is discussed as an example of how the effects might be observationally accessible.Comment: 14 pages, 7 figures; v2 references adde

Modélisation de l'architecture des plantes. Application aux plantes agronomiques pérennes tropicales : cas particulier des Palmacea

Mise au point par le laboratoire de modélisation du CIRAD de techniques d'observations de terrain en s'appuyant sur les concepts de l'architecture des plantes. Développement de méthodes d'analyse statistique des lois de probabilité qui en résultent, en s'inspirant des méthodes de la recherche opérationnelle. Développement d'un logiciel qui permet le calcul et la simulation des plantes et qui respecte stochastiquement ces lois et ces stratégies; ce logiciel est basé sur le principe d'un "moteur de croissance" en référence aux moteurs d'inférence. Quelques exemples sont donnés sur le caféier, le cotonnier, le litchi, l'hévéa, le palmier à huile et le cocotier. Des applications, des débouchés actuels et potentiels d'une telle modélisation sont présentés, en particulier ceux envisagés avec l'IRHO sur le palmier et le cocotie

The volume operator in covariant quantum gravity

A covariant spin-foam formulation of quantum gravity has been recently developed, characterized by a kinematics which appears to match well the one of canonical loop quantum gravity. In particular, the geometrical observable giving the area of a surface has been shown to be the same as the one in loop quantum gravity. Here we discuss the volume observable. We derive the volume operator in the covariant theory, and show that it matches the one of loop quantum gravity, as does the area. We also reconsider the implementation of the constraints that defines the model: we derive in a simple way the boundary Hilbert space of the theory from a suitable form of the classical constraints, and show directly that all constraints vanish weakly on this space.Comment: 10 pages. Version 2: proof extended to gamma > 1

A new look at loop quantum gravity

I describe a possible perspective on the current state of loop quantum gravity, at the light of the developments of the last years. I point out that a theory is now available, having a well-defined background-independent kinematics and a dynamics allowing transition amplitudes to be computed explicitly in different regimes. I underline the fact that the dynamics can be given in terms of a simple vertex function, largely determined by locality, diffeomorphism invariance and local Lorentz invariance. I emphasize the importance of approximations. I list open problems.Comment: 15 pages, 5 figure

Physical boundary Hilbert space and volume operator in the Lorentzian new spin-foam theory

A covariant spin-foam formulation of quantum gravity has been recently developed, characterized by a kinematics which appears to match well the one of canonical loop quantum gravity. In this paper we reconsider the implementation of the constraints that defines the model. We define in a simple way the boundary Hilbert space of the theory, introducing a slight modification of the embedding of the SU(2) representations into the SL(2,C) ones. We then show directly that all constraints vanish on this space in a weak sense. The vanishing is exact (and not just in the large quantum number limit.) We also generalize the definition of the volume operator in the spinfoam model to the Lorentzian signature, and show that it matches the one of loop quantum gravity, as does in the Euclidean case.Comment: 11 page

On the Relation between Operator Constraint --, Master Constraint --, Reduced Phase Space --, and Path Integral Quantisation

Path integral formulations for gauge theories must start from the canonical formulation in order to obtain the correct measure. A possible avenue to derive it is to start from the reduced phase space formulation. In this article we review this rather involved procedure in full generality. Moreover, we demonstrate that the reduced phase space path integral formulation formally agrees with the Dirac's operator constraint quantisation and, more specifically, with the Master constraint quantisation for first class constraints. For first class constraints with non trivial structure functions the equivalence can only be established by passing to Abelian(ised) constraints which is always possible locally in phase space. Generically, the correct configuration space path integral measure deviates from the exponential of the Lagrangian action. The corrections are especially severe if the theory suffers from second class secondary constraints. In a companion paper we compute these corrections for the Holst and Plebanski formulations of GR on which current spin foam models are based.Comment: 43 page

The Holst Spin Foam Model via Cubulations

Spin foam models are an attempt for a covariant, or path integral formulation of canonical loop quantum gravity. The construction of such models usually rely on the Plebanski formulation of general relativity as a constrained BF theory and is based on the discretization of the action on a simplicial triangulation, which may be viewed as an ultraviolet regulator. The triangulation dependence can be removed by means of group field theory techniques, which allows one to sum over all triangulations. The main tasks for these models are the correct quantum implementation of the Plebanski constraints, the existence of a semiclassical sector implementing additional "Regge-like" constraints arising from simplicial triangulations, and the definition of the physical inner product of loop quantum gravity via group field theory. Here we propose a new approach to tackle these issues stemming directly from the Holst action for general relativity, which is also a proper starting point for canonical loop quantum gravity. The discretization is performed by means of a "cubulation" of the manifold rather than a triangulation. We give a direct interpretation of the resulting spin foam model as a generating functional for the n-point functions on the physical Hilbert space at finite regulator. This paper focuses on ideas and tasks to be performed before the model can be taken seriously. However, our analysis reveals some interesting features of this model: first, the structure of its amplitudes differs from the standard spin foam models. Second, the tetrad n-point functions admit a "Wick-like" structure. Third, the restriction to simple representations does not automatically occur -- unless one makes use of the time gauge, just as in the classical theory.Comment: 25 pages, 1 figure; v3: published version. arXiv admin note: substantial text overlap with arXiv:0911.213

Oriented Matroids -- Combinatorial Structures Underlying Loop Quantum Gravity

We analyze combinatorial structures which play a central role in determining spectral properties of the volume operator in loop quantum gravity (LQG). These structures encode geometrical information of the embedding of arbitrary valence vertices of a graph in 3-dimensional Riemannian space, and can be represented by sign strings containing relative orientations of embedded edges. We demonstrate that these signature factors are a special representation of the general mathematical concept of an oriented matroid. Moreover, we show that oriented matroids can also be used to describe the topology (connectedness) of directed graphs. Hence the mathematical methods developed for oriented matroids can be applied to the difficult combinatorics of embedded graphs underlying the construction of LQG. As a first application we revisit the analysis of [4-5], and find that enumeration of all possible sign configurations used there is equivalent to enumerating all realizable oriented matroids of rank 3, and thus can be greatly simplified. We find that for 7-valent vertices having no coplanar triples of edge tangents, the smallest non-zero eigenvalue of the volume spectrum does not grow as one increases the maximum spin \jmax at the vertex, for any orientation of the edge tangents. This indicates that, in contrast to the area operator, considering large \jmax does not necessarily imply large volume eigenvalues. In addition we give an outlook to possible starting points for rewriting the combinatorics of LQG in terms of oriented matroids.Comment: 43 pages, 26 figures, LaTeX. Version published in CQG. Typos corrected, presentation slightly extende