Bipartite partial duals and circuits in medial graphs

It is well known that a plane graph is Eulerian if and only if its geometric dual is bipartite. We extend this result to partial duals of plane graphs. We then characterize all bipartite partial duals of a plane graph in terms of oriented circuits in its medial graph.Comment: v2: minor changes. To appear in Combinatoric

On the Effective Action of Noncommutative Yang-Mills Theory

We compute here the Yang-Mills effective action on Moyal space by integrating over the scalar fields in a noncommutative scalar field theory with harmonic term, minimally coupled to an external gauge potential. We also explain the special regularisation scheme chosen here and give some links to the Schwinger parametric representation. Finally, we discuss the results obtained: a noncommutative possibly renormalisable Yang-Mills theory.Comment: 19 pages, 6 figures. At the occasion of the "International Conference on Noncommutative Geometry and Physics", April 2007, Orsay (France). To appear in J. Phys. Conf. Se

One-loop Beta Functions for the Orientable Non-commutative Gross-Neveu Model

We compute at the one-loop order the beta-functions for a renormalisable non-commutative analog of the Gross Neveu model defined on the Moyal plane. The calculation is performed within the so called x-space formalism. We find that this non-commutative field theory exhibits asymptotic freedom for any number of colors. The beta-function for the non-commutative counterpart of the Thirring model is found to be non vanishing.Comment: 16 pages, 9 figure

Renormalization of Non-Commutative Phi^4_4 Field Theory in x Space

In this paper we provide a new proof that the Grosse-Wulkenhaar non-commutative scalar Phi^4_4 theory is renormalizable to all orders in perturbation theory, and extend it to more general models with covariant derivatives. Our proof relies solely on a multiscale analysis in x space. We think this proof is simpler and could be more adapted to the future study of these theories (in particular at the non-perturbative or constructive level).Comment: 32 pages, v2: correction of lemmas 3.1 and 3.2 with no consequence on the main resul

Mechanically activated piezo channels modulate outflow tract valve development through the Yap1 and Klf2-Notch signaling axis

Mechanical forces are well known for modulating heart valve developmental programs. Yet, it is still unclear how genetic programs and mechanosensation interact during heart valve development. Here, we assessed the mechanosensitive pathways involved during zebrafish outflow tract (OFT) valve development in vivo. Our results show that the hippo effector Yap1, Klf2, and the Notch signaling pathway are all essential for OFT valve morphogenesis in response to mechanical forces, albeit active in different cell layers. Furthermore, we show that Piezo and TRP mechanosensitive channels are important factors modulating these pathways. In addition, live reporters reveal that Piezo controls Klf2 and Notch activity in the endothelium and Yap1 localization in the smooth muscle progenitors to coordinate OFT valve morphogenesis. Together, this work identifies a unique morphogenetic program during OFT valve formation and places Piezo as a central modulator of the cell response to forces in this process

Degenerate noncommutativity

We study a renormalizable four dimensional model with two deformed quantized space directions. A one-loop renormalization is performed explicitly. The Euclidean model is connected to the Minkowski version via an analytic continuation. At a special value of the parameters a nontrivial fixed point of the renormalization group occurs.Comment: 16 page

Innovative Approaches to Analysing Carbon Sequestration as a Mitigation Strategy in Tropical Pasture Landscapes in Two Emblematic Contexts, the Amazon and the West African Sahel

The relationship between ruminant production systems and climate change is complex. As a major contributor to greenhouse gas (GHG) emissions, the sector has been the subject of considerable controversy, with particularly severe criticism in the 2000s. However, ten years ago, the attitude towards grazing lands began to change. Their efficient use of non-renewable energy and their contribution to carbon (C) sequestration were considered as key factors in the new environmental challenge. The reality of this mitigation potential was recently called into question once again in the global agriculture and climate change debate, including that of sequestration in the soil where grazing lands occupy a major position (30-40% of the land surface representing 30% of the soil organic C of the world). Few scientific references are available on these questions in tropical regions, and the standard metrics and methods used may turn out to be unsuitable for the correct evaluation of grazed ecosystems in these regions. Significant work is therefore required to establish baselines and design strategies to ensure sustainable grazing in these regions where the global sequestration potential is high relative to the surface areas concerned. To contribute to this debate, we focus on mitigation options offered by rangelands and grasslands and their management in two emblematic tropical contexts, humid and dry tropics, where field studies have been based on original and holistic approaches at different levels. In Amazonia, if curbing deforestation remains a priority, it needs to be accompanied by sustainable management of deforested areas. In the French Amazon (French Guiana), monitoring fields using chronosequences and flux towers has produced scientific knowledge on the significant mitigation capacities of grassland ecosystems. In the Brazilian Amazon, the spatial logic of the agro-ecological intensification of forage production has enabled a transition from individual extractive systems to farm management at communal levels. In the West African Sahelian region (Northern Senegal), an integrative study at landscape scale revealed the unexpected capacity of soil and shrubs for C sequestration that can offset the GHG emissions for which pastoralism in dry tropical zones is usually blamed

Exorcizing the Landau Ghost in Non Commutative Quantum Field Theory

We show that the simplest non commutative renormalizable field theory, the $\phi^4$ model on four dimensional Moyal space with harmonic potential is asymptotically safe to all orders in perturbation theor

Overview of the parametric representation of renormalizable non-commutative field theory

We review here the parametric representation of Feynman amplitudes of renormalizable non-commutative quantum field models.Comment: 10 pages, 3 figures, to be published in "Journal of Physics: Conference Series

Vacuum configurations for renormalizable non-commutative scalar models

In this paper we find non-trivial vacuum states for the renormalizable non-commutative $\phi^4$ model. An associated linear sigma model is then considered. We further investigate the corresponding spontaneous symmetry breaking.Comment: 17 page