Problems on infinite sumset configurations in the integers and beyond

In contrast to finite arithmetic configurations, relatively little is known about which infinite patterns can be found in every set of natural numbers with positive density. Building on recent advances showing infinite sumsets can be found, we explore numerous open problems and obstructions to finding other infinite configurations in every set of natural numbers with positive density.Comment: 37 page

Etude Sedimentologique et Esquisse Paleoenvironnementale des Formations de fresco

Les analyses sédimentologiques réalisées dans ce travail, sont un prélude d’un projet d’études pluridisciplinaires intégrant la sédimentologie, la biostratigraphie et les paléoenvironnements des formations géologiques de Fresco. Elles s’appuient sur l’étude de 227 échantillons de déblais des sondages Fresco 1 et Fresco 2, situés dans la partie occidentale du bassin côtier ivoirien. Elles ont abouti à une meilleure approche de l’origine du matériel sédimentaire, du milieu de dépôt, des conditions hydrodynamiques et de l’âge relatif des formations dans le périmètre d’étude. Elles indiquent en effet, une sédimentation argileuse et sableuse dominante, à intercalations de grès et de calcaires, généralement glauconieuse et phosphatée dans la partie supérieure. Les dinokystes rencontrés sont essentiellement d’origine marine et caractérisent trois étages (Maastrichtien, Palèocène et Eocène inférieur). Les sables analysés sont à grains moyens à grossiers, très bien classés, symétriques à asymétriques vers les éléments fins. Cette sédimentation, présentant des faciès de type sigmoïde, s’est faite par accumulation libre, par saltation et par suspension. Les grains de quartz majoritairement sub-anguleux à sub-arrondis suggèrent une source pourvoyeuse relativement distale tandis que leur aspect émoussé luisant évoque un séjour en milieu aquatique. Deux intervalles carbonatés décrits dans chacun des deux sondages traduisent deux pulsations marines franches sur une plateforme continentale interne à bathyale.Mots clés : sédimentologie, paléoenvironnement, formations de Fresco, Côte d’Ivoire

Use of Experimental Design for Peuhl Cheese Process Optimization

This work points out the use of experimental design for peulh cheese making process optimisation. Peulh cheese, a milk coagulum, well-known in certain West African countries (e.g. Benin), is unfortunately ill-known in C\uf4te d'Ivoire (Ivory Coast). However, it could be a transformation way of milk. This work consisting in use of a central composite design enables the determination of optimal process conditions concerning: leaf extract volume added (7 mL), heating temperature (84.12\ub0C) and heating time (15 min). When these optimal conditions are reached, the maximal value for process yield is 58.88 %, the minimal value for TCB is 6.40 min and the value found for total solids is 42.75 %. Furthermore, this work has showed that the experimental design is more suitable than the traditional study method called "one factor at a time". @JASE

Quantum Field Theories on Algebraic Curves. I. Additive bosons

Using Serre's adelic interpretation of cohomology, we develop a `differential and integral calculus' on an algebraic curve X over an algebraically closed filed k of constants of characteristic zero, define algebraic analogs of additive multi-valued functions on X and prove corresponding generalized residue theorem. Using the representation theory of the global Heisenberg and lattice Lie algebras, we formulate quantum field theories of additive and charged bosons on an algebraic curve X. These theories are naturally connected with the algebraic de Rham theorem. We prove that an extension of global symmetries (Witten's additive Ward identities) from the k-vector space of rational functions on X to the vector space of additive multi-valued functions uniquely determines these quantum theories of additive and charged bosons.Comment: 31 pages, published version. Invariant formulation added, multiplicative section remove

First report of a phytoplasma affecting cassava orchards in Cote d'Ivoire

Annex 46 of 48 for CIFSRF-IDRC/GAC Final technical report: http://hdl.handle.net/10625/56415This work was carried out with the aid of a grant from Canada’s International Development Research Centre (IDRC), and with financial support from the Government of Canada, provided through Global Affairs Canada (GAC)This is the first report of a phytoplasma affecting cassava in Côte d'Ivoire. The findings suggest that cassava may be a potential alternative host for the Côte d'Ivoire lethal yellowing (CILY) phytoplasma, which poses a serious threat for the food security of smallholder coconut and cassava farmers, especially women, in Grand-Lahou, Côte d’Ivoire. Leaf samples were collected at random from 12 symptom-bearing and two symptomless cassava plants from two villages. Illustrations/ figures depict the symptoms of yellowing. Cassava (Manihot esculenta) is one of the staple foods in Africa, cultivated in 40 countries and producing more than three million tonnes per year

Hamiltonian structure and quantization of 2+1 dimensional gravity coupled to particles

It is shown that the reduced particle dynamics of 2+1 dimensional gravity in the maximally slicing gauge has hamiltonian form. This is proved directly for the two body problem and for the three body problem by using the Garnier equations for isomonodromic transformations. For a number of particles greater than three the existence of the hamiltonian is shown to be a consequence of a conjecture by Polyakov which connects the auxiliary parameters of the fuchsian differential equation which solves the SU(1,1) Riemann-Hilbert problem, to the Liouville action of the conformal factor which describes the space-metric. We give the exact diffeomorphism which transforms the expression of the spinning cone geometry in the Deser, Jackiw, 't Hooft gauge to the maximally slicing gauge. It is explicitly shown that the boundary term in the action, written in hamiltonian form gives the hamiltonian for the reduced particle dynamics. The quantum mechanical translation of the two particle hamiltonian gives rise to the logarithm of the Laplace-Beltrami operator on a cone whose angular deficit is given by the total energy of the system irrespective of the masses of the particles thus proving at the quantum level a conjecture by 't Hooft on the two particle dynamics. The quantum mechanical Green's function for the two body problem is given.Comment: 34 pages LaTe

An SU(N) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling

The Hubbard model, containing only the minimum ingredients of nearest neighbor hopping and on-site interaction for correlated electrons, has succeeded in accounting for diverse phenomena observed in solid-state materials. One of the interesting extensions is to enlarge its spin symmetry to SU(N>2), which is closely related to systems with orbital degeneracy. Here we report a successful formation of the SU(6) symmetric Mott insulator state with an atomic Fermi gas of ytterbium (173Yb) in a three-dimensional optical lattice. Besides the suppression of compressibility and the existence of charge excitation gap which characterize a Mott insulating phase, we reveal an important difference between the cases of SU(6) and SU(2) in the achievable temperature as the consequence of different entropy carried by an isolated spin. This is analogous to Pomeranchuk cooling in solid 3He and will be helpful for investigating exotic quantum phases of SU(N) Hubbard system at extremely low temperatures.Comment: 20 pages, 6 figures, to appear in Nature Physic

Resting State Functional Connectivity in Perfusion Imaging: Correlation Maps with BOLD Connectivity and Resting State Perfusion

Functional connectivity is a property of the resting state that may provide biomarkers of brain function and individual differences. Classically, connectivity is estimated as the temporal correlation of spontaneous fluctuations of BOLD signal. We investigated differences in connectivity estimated from the BOLD and CBF signal present in volumes acquired with arterial spin labeling technique in a large sample (N = 265) of healthy individuals. Positive connectivity was observable in both BOLD and CBF signal, and was present in the CBF signal also at frequencies lower than 0.009 Hz, here investigated for the first time. Negative connectivity was more variable. The validity of positive connectivity was confirmed by the existence of correlation across individuals in its intensity estimated from the BOLD and CBF signal. In contrast, there was little or no correlation across individuals between intensity of connectivity and mean perfusion levels, suggesting that these two biomarkers correspond to distinct sources of individual differences