Charge profile of surface doped C60

We study the charge profile of a C60-FET (field effect transistor) as used in the experiments of Schoen, Kloc and Batlogg. Using a tight-binding model, we calculate the charge profile treating the Coulomb interaction in a mean-field approximation. The charge profile behaves similarly to the case of a continuous space-charge layer, in particular it is confined to a single interface layer for doping higher than ~0.3 electron (or hole) per C60 molecule. The morahedral disorder of the C60 molecules smoothens the structure in the density of states.Comment: 6 pages, 9 figure

Novel families of SU(N){\rm SU}(N) AKLT states with arbitrary self-conjugate edge states

Using the Matrix Product State framework, we generalize the Affleck-Kennedy-Lieb-Tasaki (AKLT) construction to one-dimensional spin liquids with global color ${\rm SU}(N)$ symmetry, finite correlation lengths, and edge states that can belong to any self-conjugate irreducible representation (irrep) of ${\rm SU}(N)$. In particular, ${\rm SU}(2)$ spin-$1$ AKLT states with edge states of arbitrary spin $s=1/2,1,3/2,\cdots$ are constructed, and a general formula for their correlation length is given. Furthermore, we show how to construct local parent Hamiltonians for which these AKLT states are unique ground states. This enables us to study the stability of the edge states by interpolating between exact AKLT Hamiltonians. As an example, in the case of spin-$1$ physical degrees of freedom, it is shown that a quantum phase transition of central charge $c = 1$ separates the Symmetry Protected Topological (SPT) phase with spin-$1/2$ edge states from a topologically trivial phase with spin-$1$ edge states. We also address some specificities of the generalization to ${\rm SU}(N)$ with $N>2$, in particular regarding the construction of parent Hamiltonians. For the AKLT state of the ${\rm SU}(3)$ model with the $3$-box symmetric representation, we prove that the edge states are in the $8$-dimensional adjoint irrep, and for the ${\rm SU}(3)$ model with adjoint irrep at each site, we are able to construct two different reflection-symmetric AKLT Hamiltonians, each with a unique ground state which is either even or odd under reflection symmetry and with edge states in the adjoint irrep. Finally, examples of two-column and adjoint physical irreps for ${\rm SU}(N)$ with $N$ even and with edge states living in the antisymmetric irrep with $N/2$ boxes are given, with a conjecture about the general formula for their correlation lengths.Comment: 37 pages, 14 figures, 4 table

L'alimentation à Tours à la fin du Moyen Age

Panneaux d'une exposition aux Archives municipales de Tours (France) du 18 novembre 2011 au 6 janvier 2012Du 18 novembre 2011 au 6 janvier 2012 s'est tenue aux archives municipales de Tours une exposition sur l'Alimentation à Tours à la fin du Moyen Age. Cette exposition présente en 13 panneaux les différentes aspects de l'alimentation tourangelle aux XIVe et XVe siècle, au travers de données issues des comptes de la villes et des fouilles archéologiques. L'exposition est organisée selon 3 axes : 1 - Contexte (Tours au XVe siècle : Une ville, un siècle ; Les sources, miel des historiens et des archéologues) 2 - Les aliments (Ce que l'on mange ; Ce que l'on boit ; L'approvisionnement de Tours ; Le conditionnement des produits alimentaires) 3 - Alimentation et société (Plats, pots et pichets : la vaisselle ; une alimentation diversifiée ; commercialisation et préparation des denrées ; Tours, une "vache à lait" : alimentation et fiscalité ; Cadeaux alimentaires et pots de vin ; Quand la ville reçoit... Les banquets urbains

Transport of species in a fibrous media during tissue growth

Tissue engineering is of major importance in biomedical transplantation techniques. However, some questions subsist as for example the mass transport between each pahse (cell, fluide and solid). In a previous paper, a one-equation model was developed in order to model mass transport during in vitro tissue growth using the volume averaging method. Using a dimensionless form of the model and a convenient formulation of the effective dispersion tensor, a numerical resolution of the closure problem is proposed. Some results allowing to validate the numerical tool are presented. This validation is carried out using results available in the literature for 2-D unit cells and under-classes of our model (namely diffusion, diffusion/reaction and diffusion/advection problems). Finally, we provide some results for the complete model taking into account diffusion, reaction and advection in the three phase system

In-vitro cartilage growth: macroscopic mass transport modelling in a three-phase system

Transplantation of engineered tissues is of major interest as an alternative to autogenic alogenic or exogenic grafts. In this study, in vitro cartilage cell culture on a fibrous biodegradable polymer scaffold is under concern. The scaffold is first seeded with cells which adhere to the fibres and the system is then grown in a bioreactor. As reported in the literature, hydrodynamics and transport of nutrients and metabolic products during this growth process is of considerable importance, motivating our analysis. A one-equation macroscopic model was first developed in order to describe macroscopic mass transport during in vitro tissue growth using the volume averaging method. This model takes into account a three phase system composed of solid fibres, cell phase and fluid phase and allows determination of the macroscopic quantities as a function of microscopic properties and geometry at any stage of growth. In a second step, numerical tools for the computation of the effective properties were developed and validated. This validation is carried out using results available in the literature for some sub-classes of our model (namely, diffusion, diffusion/reaction and diffusion/advection problems in 2D systems). The behaviour of the macroscopic dispersion tensor for the complete model (diffusion/reaction/advection) in a three phase configuration is studied and the influence of different parameters such as the volume fractions of the phases, Peclet and Kinetic numbers is discussed

Analysis of the Determinants of the Technical Efficiency of Horticultural Production in the Face of the Degradation of Water Reservoirs in Urban Centers in Burkina Faso

Horticulture activity represents one of the most important sources of income for the populations living near the water reservoirs in the city of Ouagadougou. However, its production is threatened by the increasingly and pronounced deterioration of reservoirs. In this article, we aim to measure the technical efficiency of horticulturalists in such a context. To achieve this goal, the stochastic production frontier method was carried out on a representative sample of 128 horticultural operators. The outcomes of the research reveal that overall horticulturalists are not technically efficient. In fact, the average level of technical efficiency is 0.68. The technical inefficiency evaluated to 0.32 is mainly due to the social status of the operator, the location of the plot with respect to the flow of water, and the poor state of water and soil. Keywords: Horticulture, Coelli and Battesse model, Technical efficiency, Water reservoirs DOI: 10.7176/JESD/11-12-13 Publication date:June 30th 202

DKPN: A Composite Dataflow/Kahn Process Networks Execution Model

International audienceTo address the high level of dynamism and variability in modern streaming applications (e.g. video decoding) as well as the difficulties in programming heterogeneous MPSoCs, we propose a novel execution model based upon both dataflow and Kahn process networks. This paper presents the semantics and properties of this hierarchical and parametric model, called DKPN. Parameters are classified and it is shown that hints can be derived to improve the execution. A scheduler framework and policies to back the model are also exposed. Experiments illustrate the benefits of our approach

Mineral magnetic characterization of the Upper Pleniglacial Nussloch loess sequence (Germany): an insight into local environmental processes

International audience(1) First comprehensive environmental magnetism study of the Nussloch (Rhine River Valley, Germany) loess/palaeosol deposit. (2) Bulk ferrimagnetic concentration parameters are dominantly controlled by variations in coarse-grained MD ferrimagnetic particles of detrital aeolian origin. (3) The imprint of waterlogging-induced redoxomorphic processes on the magnetic record is observed by dissolution of fine-grained magnetic minerals. (4) The interpretation of magnetic susceptibility variations alone within loess and palaeosol deposits following the wind-vigour or pedogenic enhancement models will be hindered by waterlogging-induced redoxomorphic processes, if present. S U M M A R Y Presently, most loess/palaeosol magnetic susceptibility records are interpreted as following either the wind-vigour model or the pedogenic enhancement model. However redoxomorphic processes induced by waterlogging, often referred to gleying in the loess literature, are also known to alter loess deposits but their impact on loess/palaeosol magnetic susceptibility records has received little attention. The reported rock magnetic study aims to characterize the mineral magnetic response of loess to waterlogging-induced redoxomorphic processes, thus improving our understanding of mineral magnetic changes within loess deposits with respect to environmental and climate conditions. The Nussloch loess-palaeosol deposit (Rhine Valley, Germany) was targeted because it is one of the best-studied Pleniglacial deposits for Western Europe in which numerous tundra gley intervals have been identified. Moreover, a comprehensive high-resolution environmental magnetism study has never been undertaken for this site. Various rock magnetism experiments were conducted at both room and low temperatures to characterise the composition, concentration and relative magnetic grain size of the mineral magnetic assemblage. The relative changes in magnetic parameters within the investigated loess interval are primarily controlled by (1) varying concentrations of coarse-grained ferri-magnetic particles of detrital (aeolian) origin and (2) dissolution of fine-grained ferrimagnetic particles related to in situ post-depositional alteration promoted by waterlogging-induced re-doxomorphic processes. Goethite is found to be ubiquitous throughout the studied interval and is argued to have both a primary (aeolian) and secondary (in situ) origin. We conclude, that redoxomorphic processes induced by waterlogging, if present, will hinder the interpretation of magnetic susceptibility variations within loess and palaeosol deposits following the expected relationships dictated by the wind-vigour and the pedogenic enhancement magnetism models

Combined process for 2,4-Dichlorophenoxyacetic acid treatment-Coupling of an electrochemical system with a biological treatment

International audienceA coupled process was studied for the removal of a chlorinated pesticide: 2,4-Dichlorophenoxyacetic acid (2,4-D). A home-made electrochemical flow cell was used for the pre-treatment and a biological treatment was then carried out using activated sludge supplied by a local wastewater treatment plant. 2,4-D was used as a target compound for the study. Several parameters were monitored during the biological treatment, like dissolved organic carbon (DOC), the target compound and the major by-product. Pretreatment led to a quick decrease of DOC during the biological process, since a 66% mineralization yield was measured after the second day, and 79% after the seventh day of culture. After two days of treatment, HPLC results revealed a total degradation of Chlorohydroquinone, the major by-product. The electrochemical pretreatment shortened the length of the biological treatment, since DOC measurements showed that in the case of non-pretreated 2,4-D, no mineralization was observed before day 7. These promising results should be subsequently confirmed on commercial 2,4-D-containing solutions and then on real effluents