Atomic clocks: new prospects in metrology and geodesy

We present the latest developments in the field of atomic clocks and their applications in metrology and fundamental physics. In the light of recent advents in the accuracy of optical clocks, we present an introduction to the relativistic modelization of frequency transfer and a detailed review of chronometric geodesy.Comment: Proceedings of the Workshop "Relativistic Positioning Systems and their Scientific Applications" held in Brdo near Kranj, Slovenia, 19-21 September 2012. To appear in Acta Futura (http://www.esa.int/gsp/ACT/publications/ActaFutura/

An Autonomous Reference Frame for Relativistic GNSS

Current GNSS systems rely on global reference frames which are fixed to the Earth (via the ground stations) so their precision and stability in time are limited by our knowledge of the Earth dynamics. These drawbacks could be avoided by giving to the constellation of satellites the possibility of constituting by itself a primary and autonomous positioning system, without any a priori realization of a terrestrial reference frame. Our work shows that it is possible to construct such a system, an Autonomous Basis of Coordinates, via emission coordinates. Here we present the idea of the Autonomous Basis of Coordinates and its implementation in the perturbed space-time of Earth, where the motion of satellites, light propagation, and gravitational perturbations are treated in the formalism of general relativity.Comment: 5 pages, 3 figures, in proceedings of the 4th International Colloquium: Scientific and Fundamental Aspects of the Galileo Programme, 4-6 December 2013, Prague, Czech Republic; removed unnecessary indices from eqs. 3,6,7 and corrected minus signs in eqs. 6 and

Turning block-sequential automata networks into smaller parallel networks with isomorphic limit dynamics

We state an algorithm that, given an automata network and a block-sequential update schedule, produces an automata network of the same size or smaller with the same limit dynamics under the parallel update schedule. Then, we focus on the family of automata cycles which share a unique path of automata, called tangential cycles, and show that a restriction of our algorithm allows to reduce any instance of these networks under a block-sequential update schedule into a smaller parallel network of the family and to characterize the number of reductions operated while conserving their limit dynamics. We also show that any tangential cycles reduced by our main algorithm are transformed into a network whose size is that of the largest cycle of the initial network. We end by showing that the restricted algorithm allows the direct characterization of block-sequential double cycles as parallel ones.Comment: Accepted at CIE 202

Modalites D’acquisition Des Terres Et Conflits Fonciers Dans La Sous-Prefecture De Sinfra (Cote d’Ivoire)

Cette étude vise à expliquer comment à partir des transactions foncières rurales entre populations sédentaires, naissent les conflits fonciers à Sinfra (Côte d’Ivoire). Elle s’appuie sur la théorie de l’acteur de Blumer qui privilégie l’approche idiographique dans l’explication des phénomènes sociaux. L’enquête a été effectuée auprès d’une population de 112 individus repartis selon les catégories suivantes N 1 : autorités coutumières et administratives et N2 : ruraux et cultivateurs dans les 16 villages que compte cette sous-préfecture. En termes de techniques de recherche, l’étude a eu recours à la documentation, l’observation et l’entretien. Les données révèlent que la plupart des litiges fonciers observés à Sinfra résultent des modalités d’acquisition des terres et des rixes liées aux contrats de cession élaborés par des acteurs ruraux sans qualification qui, tout en n’associant pas des acteurs habilités en la matière, se heurtent à des difficultés syntaxiques et à la reproduction textuelle de leurs aspirations dans le cadre des contrats. Parallèlement, ces partenaires fonciers qui croient que leurs aspirations sont toutes définies dans le texte, évoquent des droits qui n’apparaissent pas clairement dans le rédigé et de ce fait, agissent non pas selon le contrat écrit mais selon leurs aspirations, générant ainsi entre eux, heurts et rixes. Pour circonscrire ces conflits, l’étude plaide en faveur de l’intégration des acteurs administratifs dans le processus d’acquisition des terres rurales. This study aims to explain how, from rural land transactions between sedentary populations, land conflicts arise in Sinfra (Côte d´Ivoire). It is based on the theory of the actor of Blumer who privileges the idiographic approach in the explanation of social phenomena. The survey was carried out on a population of 112 individuals divided into the following categories L 1: customary and administrative authorities and L 2: rural people and farmers in the 16 villages of this sub-prefecture. In terms of research techniques, the study used documentation, observation and interview. The data reveal that most of the land disputes observed in Sinfra result from the terms of land acquisition and brawls linked to the sale contracts drawn up by unskilled rural actors who, while not associating actors authorized in the matter, encounter syntactic difficulties and the textual reproduction of their aspirations within the framework of contracts. At the same time, these land partners who believe that their aspirations are all defined in the text, evoke rights that do not appear clearly in the wording and therefore act not according to the written contract but according to their aspirations, thus generating between them, clashes and brawls. To reduce these conflicts, the study calls for the integration of administrative actors in the process of acquiring rural land. &nbsp

Diversité Des Espèces De Bois D’oeuvre Menacées De Disparition De La Flore De La Côte d’Ivoire, Dans Le Massif Forestier Yapo-Abbé

La présente étude a été réalisée dans le Massif Forestier Yapo-abbé (MFYA), au Sud-Est de la Côte d’Ivoire. Elle vise à évaluer la diversité des espèces de bois d’oeuvre inscrites sur la liste rouge de l’UICN (2018). La méthode de relevé de surface a été utilisée pour l’inventaire et l’identification de ces espèces dans les trois blocs forestiers du massif. Les résultats montrent que le MFYA est riche de 22 espèces de bois d’oeuvre inscrites sur la liste rouge de l’UICN (2018). Ces 22 espèces sont réparties en quinze espèces vulnérables (68,2%), cinq espèces de préoccupation mineure (22,8%), une espèce quasi-menacée (4,5%) et une autre en danger de disparition (4,5%). La fréquence d’apparition des espèces a permis d’obtenir trois groupes d’espèces : le groupe 1 (espèces constantes) compte une espèce, le groupe 2 (espèces accessoires) est constitué de six espèces ; quant au groupe 3 (espèces rares), il est composé de quinze espèces. Les trois biotopes du MFYA sont faiblement diversifiés, d’où la nécessité de les enrichir avec les espèces du groupe 3, en particulier les blocs plantations forestières et jachères, pour une gestion durable dudit massif. This study was conducted in Yapo-Abbe forest in South-Eastern Côte d'Ivoire. It aims to assess the diversity of timber species, listed on the IUCN Red List (2018). The surface survey method was used for the inventory and identification of these species in the three blocks of the forest. The results show that Yapo-Abbe forest is rich in 22 species of timber listed on the IUCN Red List (2018). These 22 species are divided into fifteen vulnerable species (68.2%), five species of low concern (22.8%), a near-threatened species (4.5%) and another species at risk of extinction (4.5%).). The frequency of occurrence of species has resulted in three groups of species; group 1 (constant species) has one species, group 2 (accessory species) consists of six species. As for group 3 (rare species), it’s composed of fifteen species. The three biotopes of Yapo-Abbe forest are poorly diversified, hence the need to enrich them with the group 3 species, especially forest plantation and fallow blocks for sustainable management of this massif

The Autumn of the World

Lost fonctionnerait comme une boussole d’orientation dans la vaste tapisserie qu’est l’Histoire de ce monde, et le spectateur de Lost, nouveau gardien de l’île, serait un spectateur dont le regard s’éduque peu à peu par le sens de l’interdépendance universelle.Lost works as an orienting compass in the vast tapestry that World History is, and the spectator of Lost, as the new protector of the island, is a spectator whose gaze is progressively educated through the sense of universal interdependence

Réflexions sur le droit à la vie privée des hommes publics dans les démocraties contemporaines : analyse à partir des cas français et camerounais

La vie privée est un droit que tout être humain se doit de bénéficier et d’exiger sa protection. Ce droit fait l’objet d’un encadrement juridique aussi bien par les textes nationaux qu’internationaux. Celui des hommes publics semble quelque peu mitigé. Aujourd’hui, le constat le plus éloquent est celui d’un ensemble de limitations, doublées des usages dont il fait l’objet ; au point où il est permis de se demander si les hommes publics bénéficient réellement de ce droit. Mais, sous un autre angle, ces limitations et ces usages ne sont pas loin d’être des atteintes occasionnant parfois des recours contentieux à l’occasion desquels le juge se montre tantôt audacieux tantôt retenu, même si l’on sait que certaines victimes préfèrent plutôt observer une certaine passivité.Private life is a right that every human being should benefit from and demand for his protection. This right is the subject of legal supervision in national and international law as well. That of public men seems to be a little bit moderated. Today, the strangest behavior is that of a set of limitations and uses which carry us to the question of: do these public men really benefit of this right? But, in the other side, these limitations and uses are sometimes the real attack and lead the disputes in front of the judge. In this occasion, the judge shows himself either daring or reserved; even if we know that some victims prefer to rather observe certain passivity

Astrophysics datamining in the classroom: Exploring real data with new software tools and robotic telescopes

Within the efforts to bring frontline interactive astrophysics and astronomy to the classroom, the Hands on Universe (HOU) developed a set of exercises and platform using real data obtained by some of the most advanced ground and space observatories. The backbone of this endeavour is a new free software Web tool - Such a Lovely Software for Astronomy based on Image J (Salsa J). It is student-friendly and developed specifically for the HOU project and targets middle and high schools. It allows students to display, analyze, and explore professionally obtained astronomical images, while learning concepts on gravitational dynamics, kinematics, nuclear fusion, electromagnetism. The continuous evolving set of exercises and tutorials is being completed with real (professionally obtained) data to download and detailed tutorials. The flexibility of the Salsa J platform tool enables students and teachers to extend the exercises with their own observations. The software developed for the HOU program has been designed to be a multi-platform, multi-lingual experience for image manipulation and analysis in the classroom. Its design enables easy implementation of new facilities (extensions and plugins), minimal in-situ maintenance and flexibility for exercise plugin. Here, we describe some of the most advanced exercises about astrophysics in the classroom, addressing particular examples on gravitational dynamics, concepts currently introduced in most sciences curricula in middle and high schools.Comment: 10 pages, 12 images, submitted to the special theme issue Using Astronomy and Space Science Research in Physics Courses of the American Journal of Physic