The geometrical interaction of the stylus and the measured surface in 3D roughness measurements

The target of this work is to study the effect of the stylus tip geometry on the surface roughness measurements by the stylus methods. A computer simulation of the measuring process in 3D using arbitrary tip shapes has been undertaken. A novel feature of this simulation is that it determines and reports the contact distribution of the contact points on the stylus when scanning each surface. Following analysis of fully simulated data to establish the fidelity of the simulation process, it was applied to data set from real surfaces. First these were examined using ideal (sometimes truncated) pyramid, conical and spherical tips. Then tip shapes determined from the measurement of real styli were used. Relatively large tips (of the order of 10 μm) were used in order to ease the need for measurement resolution. The simulation results were evaluated against real measurements of the surfaces. A bespoke measuring system was developed for this, adding X-Y scanning and a means of interchanging styli while maintaining micrometer lateral positioning between measurements. The shape of each stylus tip has been determined using a technique based on the replication by indentation into a soft substrate (typically lead). The roughness values of the real surfaces when scanned (theoretically) by the real tips have been compared to the roughness values of the same surfaces when measured by the measuring system with different tips. This comparison has shown a good compliance of both the theoretical and the practical results. This provides a degree of confidence for interpreting details of the simulation as having practical relevance. Both computer simulation and real measurements confirm the trends that would be expected from earlier studies. For example, amplitude parameters tend to drop in value as stylus size increases. The distribution of stylus contacts in simulation suggests that it is rarely to be found near the nominal centre of the tip. It is also clearly demonstrated that real worn tips do not necessary act as if blunt, contacts concentration in small regions when local features dominate. These results have significant implementations for the uncertainty in topographic measurements

Comparative effects of autotrophic and heterotrophic growth on some vitamins, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, amino acids and protein profile of Chlorella vulgaris Beijerinck

Chemical composition of Chlorella vulgaris Beijerinck including content of some vitamins (A, E and C), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, amino acids and protein profile was assessed under autotrophic and heterotrophic growth conditions as an indication of its nutritional value. Vitamin content (A, E and C) of heterotrophic cells increased by about 29, 52 and 20, respectively, as compared to its value for autotrophic cells. The free radical scavenging activity (RSA) was significantly higher for autotrophic cells than heterotrophic only at low concentrations (25 and 50 μl) of algal extract, but no significant difference was recorded at high concentration (100 μl). This result indicates non parallel relationship between the tested vitamins and RSA which suggest that other nonenzymatic antioxidants and/or antioxidant enzymes are involved. Concentration of essential and non essential amino acids in heterotrophic cells was double and 1.5 times, respectively its concentration in autotrophic cells. Histidine, lysine and phenylalanine constituted 77 and 44% of the total content of essential amino acids in heterotrophic and autotrophic cells, respectively. Methionine concentration was low in both types of cells. Proline content and non essential amino acid in heterotrophic cells was about 2.5 times its corresponding value in autotrophic cells. SDS-PAGE of protein extracts of autotrophic and heterotrophic C. vulgaris revealed two protein bands of molecular weight of ~75 and ~39 KDa. Higher intensity of the two bands was observed for autotrophic cells which may be associated with the effect of growth condition on the expression of regulatory genes. For valuable production of natural food supplement and/or natural pharmaceutical products, using heterotrophic cells rather than autotrophic cells for its richness in vitamins and essential amino acids is recommended.Key words: Autotrophic, heterotrophic, Chlorella vulgaris, vitamins, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, amino acid, protein profile

The geometrical interaction of the stylus and the measured surface in 3D roughness measurements

The target of this work is to study the effect of the stylus tip geometry on the surface roughness measurements by the stylus methods. A computer simulation of the measuring process in 3D using arbitrary tip shapes has been undertaken. A novel feature of this simulation is that it determines and reports the contact distribution of the contact points on the stylus when scanning each surface. Following analysis of fully simulated data to establish the fidelity of the simulation process, it was applied to data set from real surfaces. First these were examined using ideal (sometimes truncated) pyramid, conical and spherical tips. Then tip shapes determined from the measurement of real styli were used. Relatively large tips (of the order of 10 μm) were used in order to ease the need for measurement resolution. The simulation results were evaluated against real measurements of the surfaces. A bespoke measuring system was developed for this, adding X-Y scanning and a means of interchanging styli while maintaining micrometer lateral positioning between measurements. The shape of each stylus tip has been determined using a technique based on the replication by indentation into a soft substrate (typically lead). The roughness values of the real surfaces when scanned (theoretically) by the real tips have been compared to the roughness values of the same surfaces when measured by the measuring system with different tips. This comparison has shown a good compliance of both the theoretical and the practical results. This provides a degree of confidence for interpreting details of the simulation as having practical relevance. Both computer simulation and real measurements confirm the trends that would be expected from earlier studies. For example, amplitude parameters tend to drop in value as stylus size increases. The distribution of stylus contacts in simulation suggests that it is rarely to be found near the nominal centre of the tip. It is also clearly demonstrated that real worn tips do not necessary act as if blunt, contacts concentration in small regions when local features dominate. These results have significant implementations for the uncertainty in topographic measurements.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

From the global food crisis, to food sovereignty : a food regimes analysis : the Egyptian case study

La question agraire a connu un regain d'intérêt après la crise alimentaire de 2007-2008 qui a engendré des émeutes de la faim en Egypte. Ces émeutes ont montré l'urgence de trouver un modèle agroalimentaire alternatif qui remette les paysans au centre des politiques agroalimentaires et qui rende le système agroalimentaire égyptien moins vulnérable aux chocs externes. L'analyse holistique du système agroalimentaire mondial en termes de Food Regimes sert de cadre théorique pour étudier le cas égyptien. L'Egypte ayant subi la colonisation britannique, la forte dépendance de l'aide alimentaire américaine et la prolifération du « Corporate Food Regimes » représente un cas d'école d'un système résultant de ses trois « Food Regimes ». Depuis la libéralisation des politiques agricoles et les réformes foncières connexes, les paysans « fellahin » égyptiens font face à des défis insurmontables. Les revendications des mouvements paysans et de la société civile ont abouti à reconnaitre le droit à la souveraineté alimentaire dans la nouvelle constitution égyptienne de 2014, ce qui marque une victoire historique de ses mouvements. Néanmoins, l'analyse du système agroalimentaire montre que le modèle néolibéral productiviste défaillant prédomine encore les politiques agricoles et les relations socioéconomiques en Egypte. Cette étude propose un cadre opérationnel alternatif mobilisant trois outils politique, technique et juridique pour la mise en place d'un programme alternatif des politiques agroalimentaires qui remédie à la « dépaysannisation » et la paupérisation perpétuelle des paysans égyptiens et à la crise écologique actuelle.The agrarian question has gained renewed interest after the food crisis of 2007-2008 which led to food riots in Egypt. These riots revealed the pressing need to find an alternative agro-food model that puts farmers back at the center of agro-food policies and render the Egyptian food system less vulnerable to external shocks. The holistic analysis of the global food system in terms of food regimes serves as a theoretical framework to study the Egyptian case. Egypt, having undergone British colonization, heavy dependency on American food aid and the proliferation of Corporate Food Regimes is a representative case of a system derived from these three Food Regimes. Since the liberalization of agricultural policies and related land reforms, Egyptian "fellahin" peasants have faced daunting challenges. The claims of peasant movements and civil society led to the recognition of the right to food sovereignty in the new Egyptian constitution in 2014, which marks a historic victory for these movements. Nevertheless, the analysis of the food system shows that the failed neoliberal industrial model still dominates agricultural policies and socioeconomic relations in Egypt. This study therefore proposes an alternative operational framework mobilizing three political, technical, and legal tools for the implementation of an alternative agri-food policy program that remedies the perpetual depeasantization and impoverishment of Egyptian farmers and the current ecological crisis

The Ukraine-Russia War: A Deepening of the Chronic Food Dependency in Egypt

International audienc

Exploitation of predator-prey associates

A continuous-time model, describing the interaction between a "'facultative"' predator and a prey is used to study the consequences of exploitation of either the predator, the prey or both. The model assumes a logistic growth pattern in absence of the interaction. The change in steady-state levels of the associates due to different combinations of fishing intensities are described mathematically and diagrammatically. The effect of density of predation, on the equilibrium populations associated with the yield of either, or both, the predator and the prey are studied. Yield curves were constructed for both the predator and the prey under different fishing intensities of the other associate. The model is given in a discrete-time form, of which the stochastic version is derived to show the effect of intrinsic variability. The stochastic version was simulated on the computor through the use of random normal deviates. Fair agreement between the calculated values of the variances of the steady states, and those empirically found through simulation is listed. This simple structural model reveals that in such an association, fishing the prey population alone gives a lower maximum sustained yield than can be maintained, if the predator is also fished. It is hoped that such a model, which is a preliminary but a necessary step, will lead to a more comprehensive model applicable to natural fish populations.Science, Faculty ofZoology, Department ofGraduat

Le développement économique de l'Égypte depuis 1952

Dowidar Mohammed. Le développement économique de l'Égypte depuis 1952. In: Tiers-Monde, tome 5, n°18, 1964. pp. 255-272