Asymptotics of generalized Hadwiger numbers

We give asymptotic estimates for the number of non-overlapping homothetic copies of some centrally symmetric oval $B$ which have a common point with a 2-dimensional domain $F$ having rectifiable boundary, extending previous work of the L.Fejes-Toth, K.Borockzy Jr., D.G.Larman, S.Sezgin, C.Zong and the authors. The asymptotics compute the length of the boundary $\partial F$ in the Minkowski metric determined by $B$. The core of the proof consists of a method for sliding convex beads along curves with positive reach in the Minkowski plane. We also prove that level sets are rectifiable subsets, extending a theorem of Erd\"os, Oleksiv and Pesin for the Euclidean space to the Minkowski space.Comment: 20p, 9 figure

Analysis of sub-10 nm precipitates extracted from microalloyed steels

Microalloyed steels contain small quantities (≤ 0.5 wt%) of the microalloying elements Ti, Nb, V. Judicious combination of TMCP parameters and microalloyed steel composition leads to formation of desirable nm-sized carbide, nitride, carbonitride inclusions which improve steel mechanical properties. TMCP optimisation relies on understanding the interrelation between TMCP parameters and precipitate properties. A characterisation routine was developed in the group to provide statistically meaningful data on precipitates size distribution and chemical composition.[1] Precipitates with diameters below 10nm could not be investigated with the existing routine. Such precipitates are of interest because they play a key role in precipitation hardening. This thesis extends the existing characterisation routine to sub-10nm precipitates extracted from microalloyed steels. Electrolytic extraction was investigated as alternative extraction process to reduce undesired particle loss during chemical extraction. The suitability of various electrolytes to provide a stable colloidal suspension for colloidal analysis was assessed. Chemically extracted precipitates underwent differential centrifugation to isolate sub-10nm precipitates and enable their size and chemical composition characterisation. Improvements in precipitate analysis were achieved by implementation of speed-ramp analytical ultracentrifugation and precipitate number density determination.Mikrolegierte Stähle enthalten geringe Mengen (≤ 0.5 wt%) der Mikrolegierungselemente Ti, Nb, V. Eine geschickte Kombination aus TMCP-Parametern und Stahlzusammensetzung führt zur Bildung nm-großer Karbid-, Nitrid-, Karbonitrideinschlüsse, die mechanische Eigenschaften verbessern. TMCP-Optimierung beruht auf dem Verständnis des Zusammenhangs zwischen TMCP-Parametern und Ausscheidungseigenschaften. Eine vorhandene Charakterisierungsroutine liefert statistisch aussagekräftige Daten über die Größenverteilung und die chemische Zusammensetzung der Ausscheidungen.[ 1] Ausscheidungen mit Durchmessern unter 10nm konnten mit der bestehenden Methode nicht untersucht werden. Solche Ausscheidungen sind von Interesse, da sie eine Schlüsselrolle bei der Ausscheidungshärtung spielen. Diese Arbeit erweitert die bestehende Charakterisierungsroutine auf extrahierte Ausscheidungen kleiner 10 nm. Elektrolytische Extraktion wurde als alternatives Extraktionsverfahren erprobt, um unerwünschten Partikelverlust zu reduzieren. Die Eignung von Elektrolyten zur Bereitstellung einer stabilen kolloidalen Suspension zur Analyse mit kolloidalen Messmethoden wurde bewertet. Fraktionierung chemisch extrahierter Ausscheidungen mittels Differentialzentrifugation ermöglichte die Charakterisierung von Ausscheidungen kleiner 10 nm. Ausscheidungscharakterisierungsverbesserungen wurden durch Einführung der analytischen Ultrazentrifugation mit Geschwindigkeitsrampe und der Bestimmung der Ausscheidungsdichte erzielt

Relations entre les termitières Trinervitermes s.p. et la surface du sol : réorganisations, ruissellement et érosion

Sur un petit bassin versant du nord-ouest de la Côte d'Ivoire, les termitières de #Trinervitermes se localisent de préférence dans les zones à faible couvert herbacé, où les pellicules à la surface du sol, les indices de ruissellement et d'érosion sont les plus nombreux. La dynamique de ces états de surface suit un cycle saisonnier dans lequel le maximum d'extension des auréoles pelliculaires autour des calies se manifeste en début de saison des pluies. Elle obéit également au cycle d'édification puis d'érosion des termitières. L'utilisation de la simulation de pluies a permis de vérifier qu'aux différenciations latérales des surfaces correspondaient d'importantes différences de ruissellement et de détachabilité. Au vu des résultats, il semble que les #Trinervitermes ont tendance à dégrader la surface des sols. (Résumé d'auteur

Influence du phénomène océanique pacifique, "El Nino", sur l'upwelling et le climat de la région du Cabo Frio, sur la côte brésilienne de l'Etat de Rio de Janeiro

Le phénomène océanique pacifique connu sous le nom de "El Nino", peut perturber la circulation atmosphérique de l'Amérique du Sud et le régime des vents sur la côte Atlantique du Sud et du Sud-est du Brésil. Ceci provoque un renforcement ou une disparition de l' "upwelling" local de la région du Cabo Frio (Etat de Rio de Janeiro), avec des conséquences sur le climat et la salinité de la lagune voisine d'Araruama. Etudier ces variations, dans des sédiments lagunaires, devrait permettre d'établir une chronologie des périodes de situation de type "El Nino" et, curieusement, d'enregistrer sur la côte atlantique un phénomène océanique pacifique. (Résumé d'auteur

POLÍTICAS PÚBLICAS Y COMBATE A LA POBREZA EN SAN LUIS POTOSÍ.

In this paper, the concept of poverty is taken up from the different approaches of the organizations in the world. We emphasize the situation of poverty in the state of San Luis Potosi in Mexico. This research allows the public to know that the government implements strategies to reduce poverty in San Luis Potosi, focusing on a program "National Crusade against Hunger" and its diffusion and impact on the beneficiaries thereof. It discusses the different events, from the implementation of this program, presenting the most important achievements and results to determine their effectiveness. This basic research is documentary; it is based on journal publications and review of literature and especially the officials of the "National Crusade against Hunger"

Electrochemical impedance spectroscopy to study physiological changes affecting the red blood cell after invasion by malaria parasites

The malaria parasite, Plasmodium falciparum, invades human erythrocytes and induces dramatic changes in the host cell. The idea of this work was to use RBC modified electrode to perform electrochemical impedance spectroscopy (EIS) with the aim of monitoring physiological changes affecting the erythrocyte after invasion by the malaria parasite. Impedance cell-based devices are potentially useful to give insight into cellular behavior and to detect morphological changes. The modelling of impedance plots (Nyquist diagram) in equivalent circuit taking into account the presence of the cellular layer, allowed us pointing out specific events associated with the development of the parasite such as (i) strong changes in the host cell cytoplasm illustrated by changes in the film capacity, (ii) perturbation of the ionic composition of the host cell illustrated by changes in the film resistance, (iii) releasing of reducer (lactic acid or heme) and an enhanced oxygen consumption characterized by changes in the charge transfer resistance and in the Warburg coefficient characteristic of the redox species diffusion. These results show that the RBC-based device may help to analyze strategic events in the malaria parasite development constituting a new tool in antimalarial research

THE STATE MANAGEMENT CAPACITY INDEX IN MEXICO: A TOOL FOR MEASURING PUBLIC POLICIES IN LOCAL GOVERNMENTS

The main purpose of this paper is to present the results of the construction of a methodological instrument called the Subnational Local Governance Index (ISGL). This Index was built to contribute to the assessments of institutional capacities of local governments, in order to resolve public problems in Mexico. The construction of the Index was founded on four main features: 1) The lack of public policy in education, health, public services and housing quality, measured by the level of social backwardness, 2) the structure of government and administration, measured by the institutional capacities, 3) the quality of local government, measured by the level of credibility of the citizens through subnational governance and 4) the local financial capacity, measured by the ability to generate income and to manage the public debt. Basically, the following questions have been used to build the Index: What is the level of social backwardness at the local level? What kind of institutional structure exists at the local level? What is the profile of the public policy managers at the local level? What is the capacity to generate income? What is the level of citizens’ confidence in local governance

Ecological modelling, an objective tool for an integrated study of ecosystems

Uma exposição é feita sobre os conceitos de modelagem ecológica e sua utilização nos estudos da dinâmica dos ecossistemas marinhos. As etapas necessárias à modelagem da biomassa primária são descritas a título de exemplo teórico: (a) reunir informações quali-quantitativas sobre a estrutura do sistema (variáveis de estado) e os fatores responsáveis (variáveis forçantes), (b) o diagrama conceitual do sistema fitoplanctônico é estabelecido com os compartimentos (nutrientes, fitoplâncton, zooplancton herbívoro) e os fluxos de energia (setas interligando os compartimentos: taxa fotossintética, respiração, herbivoria...) medidos in situ ou in vitro, (c) são elaboradas as equações matemáticas do modelo, integrando cada variável em função do tempo; essas equações são em seguida programadas para processamento no computador a partir de dados reais, (d) o resultado da simulação é comparado a séries de dados reais, alterando o modelo em caso de divergência excessiva. A modelagem ecológica não é apenas um instrumento de previsão, mas constitui principalmente um meio objetivo de orientação das pesquisas e formulação de hipóteses, revelando as carências e orientando as coletas. Em razão da sua pluridisciplinaridade, a modelagem ecológica é, em fim, um instrumento de comunicação e o melhor veículo de informação entre pesquisadores das diversas áreas.The concepts of ecological modelling and its use for marine ecosystem dynamic studies are presented. The necessary steps for modelling primary biomass variations are described as theorical examples: (a) to gather quali-quantitative data on structure of the system (state variables) and on factors (forcing function), (b) a conceptual diagram of the phytoplankton system is established including compartments (nutrients, phytoplankton, herbivorous zooplankton) and energy fluxes (arrows between compartments: photosynthetic rate, respiration, grazing...) measured in situ or in vitro, (c) mathematical equations of the model are built up for each variable as a function of time: then, these equations are programmed and processed on computer with real data, (d) the result of simulation is compared to a serie of real data and the model is modified in case of excessive divergency. Ecological modelling is not only a tool for prevision, but is mainly an objective method for guiding researchs, formulating hypothesis, revealing deficiencies and orienting the sampling. Finally, on acount of its multidisciplinarity, ecological modelling is a tool of communication and the best vehicle of information between researchers of different areas