Human behaviors: a threat for mosquito control?

Community involvement and the preventive behavior of households are considered to be at the heart of vector-control strategies. In this work, we consider a simple theoretical model that enables us to take into account human behaviors that may interfere with vector control. The model reflects the trade-off between perceived costs and observed efficacy. Our theoretical results emphasize that households may reduce their protective behavior in response to mechanical elimination techniques piloted by a public agent, leading to an increase of the total number of mosquitoes in the surrounding environment and generating a barrier for vector-borne diseases control. Our study is sufficiently generic to be applied to different arboviral diseases. It also shows that vector-control models and strategies have to take into account human behaviors.Comment: 27 pages, 7 figure

Tree-Grass interactions dynamics and Pulse Fires: mathematical and numerical studies

Savannas are dynamical systems where grasses and trees can either dominate or coexist. Fires are known to be central in the functioning of the savanna biome though their characteristics are expected to vary along the rainfall gradients as observed in Sub-Saharan Africa. In this paper, we model the tree-grass dynamics using impulsive differential equations that consider fires as discrete events. This framework allows us to carry out a comprehensive qualitative mathematical analysis that revealed more diverse possible outcomes than the analogous continuous model. We investigated local and global properties of the equilibria and show that various states exist for the physiognomy of vegetation. Though several abrupt shifts between vegetation states appeared determined by fire periodicity, we showed that direct shading of grasses by trees is also an influential process embodied in the model by a competition parameter leading to bifurcations. Relying on a suitable nonstandard finite difference scheme, we carried out numerical simulations in reference to three main climatic zones as observable in Central Africa.Comment: 51 pages, 7 figure

Transition into a low temperature superconducting phase of unconventional pinning in Sr_2RuO_4

We have found a sharp transition in the vortex creep rates at a temperature T^\ast=0.05 T_c in a single crystal of Sr_2RuO_4 (T_{c}=1.03 K) by means of magnetic relaxation measurements. For T<T^\ast, the initial creep rates drop to undetectable low levels. One explanation for this transition into a phase with such extremely low vortex creep is that the low-temperature phase of Sr_2RuO_4 breaks time reversal symmetry. In that case, degenerate domain walls separating discreetly degenerate states of a superconductor can act as very strong pinning centers.Comment: 3 pages, 2 figure

Recurrence Relations for Strongly q-Log-Convex Polynomials

We consider a class of strongly q-log-convex polynomials based on a triangular recurrence relation with linear coefficients, and we show that the Bell polynomials, the Bessel polynomials, the Ramanujan polynomials and the Dowling polynomials are strongly q-log-convex. We also prove that the Bessel transformation preserves log-convexity.Comment: 15 page

Electromagnetic processing – from AC to DC Field - A way for process improvement and innovation

International audienceTechnology of Electromagnetic processing of Materials (EPM) is relatively well known and mature. This knowledge gives the possibility to improve such processes and to integrate them in specific application (aeronautics, automotive sector, metallurgy...) at industrial scale. Thanks to a transverse and multiphysics approach which combined fluid dynamics, heat transfer, process metallurgy, solidification…, it is possible to know how to design new innovative processes with the integration of new design of electromagnetic system. An association of more complex EM configurations can be achieved: combination of AC and DC field, or two AC field… Future development of EPM technologies are in agreement with energy savings and CO 2 reduction demand. In metallurgy industry, the integration of EPM technologies is more basically associated with productivity improvement, maintenance reduction and also safety consideration. EM processing can be classified by type of magnetic field involved: from AC to DC field. The choice depends on the desired action on the electro conductive materials. These processes are suitable for heating, melting, flow and shape control, solidification control (stirring, pumping)…but for each application a specific configuration needs to be defined, selected and optimized. This paper gives some examples of EPM technologies applications for the development of new industrial process and main challenge to succeed in order to be relevant: (i) cold crucible technology or levitation, (ii) electromagnetic pump and (iii) DC electromagnetic brake. A combined approach by using numerical multiphysics modeling and experimental validation is used in order to give some guidelines for process improvement, or new electromagnetic design: feasibility and potentiality for integration at industrial scale

CENP-A Is Dispensable for Mitotic Centromere Function after Initial Centromere/Kinetochore Assembly

Human centromeres are defined by chromatin containing the histone H3 variant CENP-A assembled onto repetitive alphoid DNA sequences. By inducing rapid, complete degradation of endogenous CENP-A, we now demonstrate that once the first steps of centromere assembly have been completed in G1/S, continued CENP-A binding is not required for maintaining kinetochore attachment to centromeres or for centromere function in the next mitosis. Degradation of CENP-A prior to kinetochore assembly is found to block deposition of CENP-C and CENP-N, but not CENP-T, thereby producing defective kinetochores and failure of chromosome segregation. Without the continuing presence of CENP-A, CENP-B binding to alphoid DNA sequences becomes essential to preserve anchoring of CENP-C and the kinetochore to each centromere. Thus, there is a reciprocal interdependency of CENP-A chromatin and the underlying&nbsp;repetitive centromere DNA sequences bound by CENP-B in the maintenance of human chromosome segregation