Principal Geodesic Analysis of Merge Trees (and Persistence Diagrams)

This paper presents a computational framework for the Principal Geodesic Analysis of merge trees (MT-PGA), a novel adaptation of the celebrated Principal Component Analysis (PCA) framework [87] to the Wasserstein metric space of merge trees [92]. We formulate MT-PGA computation as a constrained optimization problem, aiming at adjusting a basis of orthogonal geodesic axes, while minimizing a fitting energy. We introduce an efficient, iterative algorithm which exploits shared-memory parallelism, as well as an analytic expression of the fitting energy gradient, to ensure fast iterations. Our approach also trivially extends to extremum persistence diagrams. Extensive experiments on public ensembles demonstrate the efficiency of our approach - with MT-PGA computations in the orders of minutes for the largest examples. We show the utility of our contributions by extending to merge trees two typical PCA applications. First, we apply MT-PGA to data reduction and reliably compress merge trees by concisely representing them by their first coordinates in the MT-PGA basis. Second, we present a dimensionality reduction framework exploiting the first two directions of the MT-PGA basis to generate two-dimensional layouts of the ensemble. We augment these layouts with persistence correlation views, enabling global and local visual inspections of the feature variability in the ensemble. In both applications, quantitative experiments assess the relevance of our framework. Finally, we provide a lightweight C++ implementation that can be used to reproduce our results

Deriva del género, estabilidad de los sexos

Texto a partir de una intervención en la conferencia Erotisme et Pouvoir organizada por Michel Dion con los autores del libro dirigido por Cathy Schwichtenberg, The Madonna Connection (1993), París, IRESCO, 11 de febrero de 1994. Publicado en Michel Dion (dir) Madonna. Erotismo y Poder, Eds Kimé, “Le sens de l’histoire”, Paris, 1994, pp. 54-70. Traducción de Lourdes Méndez con la colaboración de Jules Falquet

Preservation of Gene Duplication Increases the Regulatory Spectrum of Ribosomal Protein Genes and Enhances Growth under Stress

SummaryIn baker’s yeast, the majority of ribosomal protein genes (RPGs) are duplicated, and it was recently proposed that such duplications are preserved via the functional specialization of the duplicated genes. However, the origin and nature of duplicated RPGs’ (dRPGs) functional specificity remain unclear. In this study, we show that differences in dRPG functions are generated by variations in the modality of gene expression and, to a lesser extent, by protein sequence. Analysis of the sequence and expression patterns of non-intron-containing RPGs indicates that each dRPG is controlled by specific regulatory sequences modulating its expression levels in response to changing growth conditions. Homogenization of dRPG sequences reduces cell tolerance to growth under stress without changing the number of expressed genes. Together, the data reveal a model where duplicated genes provide a means for modulating the expression of ribosomal proteins in response to stress

How Tilting the Head Interferes With Eye-Hand Coordination: The Role of Gravity in Visuo-Proprioceptive, Cross-Modal Sensory Transformations

To correctly position the hand with respect to the spatial location and orientation of an object to be reached/grasped, visual information about the target and proprioceptive information from the hand must be compared. Since visual and proprioceptive sensory modalities are inherently encoded in a retinal and musculo-skeletal reference frame, respectively, this comparison requires cross-modal sensory transformations. Previous studies have shown that lateral tilts of the head interfere with the visuo-proprioceptive transformations. It is unclear, however, whether this phenomenon is related to the neck flexion or to the head-gravity misalignment. To answer to this question, we performed three virtual reality experiments in which we compared a grasping-like movement with lateral neck flexions executed in an upright seated position and while lying supine. In the main experiment, the task requires cross-modal transformations, because the target information is visually acquired, and the hand is sensed through proprioception only. In the other two control experiments, the task is unimodal, because both target and hand are sensed through one, and the same, sensory channel (vision and proprioception, respectively), and, hence, cross-modal processing is unnecessary. The results show that lateral neck flexions have considerably different effects in the seated and supine posture, but only for the cross-modal task. More precisely, the subjects’ response variability and the importance associated to the visual encoding of the information significantly increased when supine. We show that these findings are consistent with the idea that head-gravity misalignment interferes with the visuo-proprioceptive cross-modal processing. Indeed, the principle of statistical optimality in multisensory integration predicts the observed results if the noise associated to the visuo-proprioceptive transformations is assumed to be affected by gravitational signals, and not by neck proprioceptive signals per se. This finding is also consistent with the observation of otolithic projections in the posterior parietal cortex, which is involved in the visuo-proprioceptive processing. Altogether these findings represent a clear evidence of the theorized central role of gravity in spatial perception. More precisely, otolithic signals would contribute to reciprocally align the reference frames in which the available sensory information can be encoded.This work was supported by the Centre National d’Etudes Spatiales (DAR 2017/4800000906, DAR 2018/4800000948, 2019/4800001041). JB-E was supported by a Ph.D. fellowship of the École Doctorale Cerveau-Cognition-Comportement (ED3C, n°158, Sorbonne Université and Université de Paris). The research team is supported by the Centre National de la Recherche Scientifique and the Université de Paris. This study contributes to the IdEx Université de Paris ANR-18-IDEX-0001

West Africa Climate-Smart Villages AR4D sites: 2016 Inventory

Inventory of CSA practices in West Africa's Climate-Smart Villages

The use of Lapita pottery : results from the first analysis of lipid residues

Biomolecular and isotopic characterisation of absorbed organic residues have been performed on eight dentate-stamped and two plain Lapita potsherds from the site of Teouma, in Vanuatu. Lipid profiles associated with decorated pots are homogenous, suggesting that similar food types or mixtures of food types were placed in these vessels. This suggests a high degree of consistency in the use of Lapita decorated pots, irrespective of the morphological and stylistic variation of these vessels. Data obtained from single-compound isotope analysis are also not consistent with marine resources as potential food sources for Lapita vessels. The absence of such commonly consumed, ubiquitous and easily accessible resources in Lapita vessels suggests that these pots were not manufactured to be used for ordinary occasions and day-to-day food consumption. This is the first time tangible data related to the use of these vessels are provided to support this claim in addition to contextual inferences

Mise en place d’un Village Intelligent face au Climat pour la réduction des risques climatiques et de l’insécurité alimentaire à Daga-Birame, Sénégal. Guide de visite de terrain pour la Réunion du Comité Scientifique Indépendant du CCAFS

À Daga Birame, au Sénégal, CCAFS et ses partenaires ont mis en place un village climato-intelligent (CSV) dans lequel plusieurs activités sont menées. Sur la base de la vision du village et de son avenir, un ensemble d'actions ont été identifiées par la communauté afin d'atteindre les changements souhaités dans la productivité agricole et la sécurité alimentaire tels que les activités génératrices de revenus, l'amélioration de la résilience et la gestion durable des ressources naturelles du village. Ces actions ont été structurées autour de quatre composantes: Les services d'information climatologique (SIC); le développement des technologies / pratiques agricoles adaptées au climat; le renforcement de capacités des villageois et celle des connaissances et des institutions locales

Capacitating stakeholders to using Climate Information in West Africa: Achievements and lessons learned from the WAAPP-funded CaSCIERA-TA project

This Info note summarizes the achievements and lessons learned from the implementation of a 2-year project on ‘’Capacitating Stakeholders in Using Climate Information for Enhanced Resilience in the Agricultural Sector in West Africa (CaSCIERA-TA)’’, funded by Conseil Ouest et Centre Africain pour la Recherche et le Développement Agricole (CORAF) under the West Africa Agricultural Productivity Program (WAAPP)”. This project was implemented by a consortium of partners led by ICRAF Sahel Office and included CCAFS West Africa Program, AGRHYMET, INRAB-Benin, IRAG-Guinea, INRAN-Niger and ITRA-Togo. The project aimed at strengthening the capacity of the stakeholders of four WAAPP implementing countries to mainstream and implement Climate Smart Agriculture (CSA) into their activities