EXTRAPOLATION DES SPANNUNGSINTENSITÄTSFAKTORS AUF GRUND EXPERIMENTELLER RESULTATE

The stress intensity factor (SIF) is defined usually by following formulas for the fracture-modes l and II, respectively, with the full or half crack-Iength, α, the "far-field" stress σ₀ or τ₀ and a dimensionsless quantity k₁ and k₁₁ depending on the boundary conditions. It is shown, that the actual influence of the crack-length upon the SIF is diminishing with its growing value and in many cases the SIF depends practically on the far-field stress only. This makes an extrapolation method possible, which is checked by two photoelastic experiments

Effect of Long-Term Cycling Load for Abutment Screw Fixation in Implant Prosthodontics

The aim of this in vitro study was to use rotational tests on commercially available abutment screws to evaluate their potential for preload generation and to follow changes in torque by using newer fixation geometry on the interface of the implant-abutment screw joint. Five identical implant/abutment assemblies were chosen from each of the following systems: external hex with standard abutment and Replace with TorgTite screw (Nobel Biocare), Camlog universal abutment (Altatec Biotechnologies), DenTi internal hex (Dentimplant Ltd. Szentes, Hungary), straight abutment with internal antirotational element (Uniplant, Sinalisal, Budapest). Wax patterns of the upper premolar were performed and then cast from nickel-chrome alloy and full crown castings were cemented on abutments. In a test machine the magnitude and time of chewing function was predefined by using the desired force pattern. Each specimen was stressed for cycles equivalent to an intaoral load of 5 months or longer timescale. In the static test greater loss in torques was calculated for standard Branemark and Replace screw joints. Assuming that the optimum proportion is the same when we calculate loosening versus tightening torque we obtained a decrease between 0.70-0.59 for Replace and Branemark abutments and a more moderate loss of between 0.90-0.84 for the other systems investigated. The ten month equivalent cycling test produced a loosening torque of 16-17 Ncm for Branemark and Replace abutments. Similar decrease in torque was not found for the other three systems. It was concluded that different approach in achievement of necessary mechanical integration can be seen in implant systems, although a reliable loosening torque could be measured after a longer time scale

Effect of Long-Term Cycling Load for Abutment Screw Fixation in Implant Prosthodontics

The aim of this in vitro study was to use rotational tests on commercially available abutment screws to evaluate their potential for preload generation and to follow changes in torque by using newer fixation geometry on the interface of the implant-abutment screw joint. Five identical implant/abutment assemblies were chosen from each of the following systems: external hex with standard abutment and Replace with TorgTite screw (Nobel Biocare), Camlog universal abutment (Altatec Biotechnologies), DenTi internal hex (Dentimplant Ltd. Szentes, Hungary), straight abutment with internal antirotational element (Uniplant, Sinalisal, Budapest). Wax patterns of the upper premolar were performed and then cast from nickel-chrome alloy and full crown castings were cemented on abutments. In a test machine the magnitude and time of chewing function was predefined by using the desired force pattern. Each specimen was stressed for cycles equivalent to an intaoral load of 5 months or longer timescale. In the static test greater loss in torques was calculated for standard Branemark and Replace screw joints. Assuming that the optimum proportion is the same when we calculate loosening versus tightening torque we obtained a decrease between 0.70-0.59 for Replace and Branemark abutments and a more moderate loss of between 0.90-0.84 for the other systems investigated. The ten month equivalent cycling test produced a loosening torque of 16-17 Ncm for Branemark and Replace abutments. Similar decrease in torque was not found for the other three systems. It was concluded that different approach in achievement of necessary mechanical integration can be seen in implant systems, although a reliable loosening torque could be measured after a longer time scale

Sujetos y territorios en el estudio de las migraciones desde la antropología en España

El texto hace una aproximación a la incorporación de las migraciones como temática de estudio en la Antropología en España y en qué medida la Antropología Social realizada encuentra en el inmigrante la otredad; una forma de antropologizar su estudio sin salir de casa. Se hace una breve descripción de cómo se está construyendo el campo de estudio de las migraciones a partir de la observación de las tesis doctorales que se han leído en los departamentos de Antropología Social de las universidades del Estado español en los últimos años, qué temáticas han tratado y proponiendo una agrupación organizativa del conjunto de estas investigaciones. A partir de ello analiza cómo son representados los sujetos de dichas investigaciones en los objetivos que se marcan en cada una de las tesis doctorales analizadas y los énfasis que ponen en los lugares geográficos en los que se han desarrollado las investigaciones. Palabras clave: migraciones, antropología en España, inmigrantes, tesis doctorales, territorios Abstract This article examines the incorporation into Spanish anthropology of migration as a field of study, exploring the extent to which Spanish social anthropology locates Otherness in the immigrant: a way of anthropologizing a study without leaving home. A brief description of how anthropological research in Spain constructs migration as a field of study through an overview of doctoral theses defended in the social anthropology departments of Spanish universities in recent years shows the topics studied, grouping them thematically. They are then analyzed according to how the subjects of these studies are represented (and sometimes turned into objects of study) in the stated aims of the theses analyzed, and the emphasis placed on the geographic locations in which the studies were carried out. Key words: migration, methodology, research, anthropology, doctoral theses, Spai