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Various Forces (various + force)
Selected AbstractsDefining International Entrepreneurship and Modeling the Speed of Internationalization,ENTREPRENEURSHIP THEORY AND PRACTICE, Issue 5 2005Benjamin M. Oviatt This article provides a reformulated definition of international entrepreneurship. Consistent with the new definition, a model is presented of how the speed of entrepreneurial internationalization is influenced by various forces. The model begins with an entrepreneurial opportunity and depicts the enabling forces of technology, the motivating forces of competition, the mediating perceptions of entrepreneurs, and the moderating forces of knowledge and networks that collectively determine the speed of internationalization. [source] The Road to Cotonou: Negotiating a Successor to LoméJCMS: JOURNAL OF COMMON MARKET STUDIES, Issue 3 2001Genevra Forwood The Cotonou Agreement represents a radical overhaul of EUACP relations: it both consolidates the EUACP relationship through political dialogue, and provides for the long-standing trade preferences to be replaced with regional free trade agreements. This analysis examines the various forces at work in the negotiations, using two-level game theory to assess how domestic interests influence an international negotiation. This analysis is set against the internal dynamic of EUACP relations, as well as the constraints posed by the multilateral trading system. Finally, the article examines the implications of this analysis for the forthcoming negotiations between the EU and regional ACP groups. [source] Livelihood diversification and implications on dryland resources of central TanzaniaAFRICAN JOURNAL OF ECOLOGY, Issue 2009Emma T. Liwenga Abstract The concern over sustainable livelihoods in African drylands is an issue that has received considerable attention from researchers and policy makers alike. Over the past two decades African rural areas have undergone rapid changes, whereby, rural income diversification has become the most salient feature. With a particular focus on dryland ecosystems, among the major challenges facing communities in these areas is recurrent drought leading to conditions of food insecurity. This paper draws on experience on coping mechanisms for food insecurity from an agro-pastoral community in Mvumi, located in the semiarid areas of central Tanzania. An understanding of livelihoods of people in this area has involved examining how communities have managed to adjust their livelihood in the midst of challenges resulting not only from drought but also from various forces such as socio,economic, political and ecological factors. It has been found out that, despite profound food crisis in this area, people are not always desperate and that there are possibilities for realizing some hidden potentials of dryland resources for livelihood diversification. The issue of sustainable natural resource management in such areas is, however, questionable because of some adverse environmental effects associated with some of the coping mechanisms. [source] A field guide to models of sex-ratio evolution in gynodioecious speciesOIKOS, Issue 10 2007Maia F. Bailey Gynodioecious plant species, species in which individuals are females or hermaphrodites, are ideal systems for studying connections between genetics, ecology, and long-term evolutionary changes because sex determination can be complex, involving cytoplasmic and/or nuclear genes, and sex ratio is often variable across landscapes. Field data are needed to evaluate the many theories concerning this breeding system. In order to facilitate the gathering of relevant data, this paper introduces the four types of gynodiocy (nuclear, nuclear-cytoplasmic and stochastic gynodioecy plus subdioecy), describes example species and expected patterns, discusses the various forces that drive the evolution of female frequencies, and gives concrete advice on where to start collecting data for different systems. For species in which females are relatively rare, we recommend reciprocal crosses to determine if sex-determination is nuclear or nuclear-cytoplasmic along with a search for correlations between female frequencies and ecological factors. For species in which females are common and sex ratios are highly variable, we recommend looking at female offspring sex ratios to determine if females are primarily produced in ephemeral epidemics. In the course of this discussion, we argue that the majority of natural gynodioecious species will have complex sex determination in which multiple cytoplasmic male sterility (CMS) genes interact with multiple nuclear restorers of fertility. Sex-ratio evolution in such species will be primarily influenced by fitness differences among hermaphrodites (costs of restoration) and less influenced by fitness differences between the sexes (compensation). Metapopulation dynamics alone may explain population sex ratios of species in which females are associated with marginal environments or hybrid zones; however, we feel that in most cases equilibrium forces within populations and metapopulation dynamics among populations each explain portions of the sex-ratio pattern. [source] Genetic diversity within and between European pig breeds using microsatellite markersANIMAL GENETICS, Issue 3 2006M. SanCristobal Summary An important prerequisite for a conservation programme is a comprehensive description of genetic diversity. The aim of this study was to use anonymous genetic markers to assess the between- and the within-population components of genetic diversity for European pig breeds at the scale of the whole continent using microsatellites. Fifty-eight European pig breeds and lines were analysed including local breeds, national varieties of international breeds and commercial lines. A sample of the Chinese Meishan breed was also included. Eleven additional breeds from a previous project were added for some analyses. Approximately 50 individuals per breed were genotyped for a maximum of 50 microsatellite loci. Substantial within-breed variability was observed, with the average expected heterozygosity and observed number of alleles per locus being 0.56 [range 0.43,0.68] and 4.5 respectively. Genotypic frequencies departed from Hardy,Weinberg expectations (P < 0.01) in 15 European populations, with an excess of homozygotes in 12 of them. The European breeds were on average genetically very distinct, with a Wright FST index value of 0.21. The Neighbour-Joining tree drawn from the Reynolds distances among the breeds showed that the national varieties of major breeds and the commercial lines were mostly clustered around their breeds of reference (Duroc, Hampshire, Landrace, Large White and Piétrain). In contrast, local breeds, with the exception of the Iberian breeds, exhibited a star-like topology. The results are discussed in the light of various forces, which may have driven the recent evolution of European pig breeds. This study has consequences for the interpretation of biodiversity results and will be of importance for future conservation programmes. [source] Load-related implant reaction of mini-implants used for orthodontic anchorageCLINICAL ORAL IMPLANTS RESEARCH, Issue 4 2005André Büchter Abstract: The purpose of this study was to determine the clinical and biomechanical outcome of two different titanium mini-implant systems activated with different load regimens. A total of 200 mini-implants (102 Abso Anchor® and 98 Dual Top®) were placed in the mandible of eight Göttinger minipigs. Two implants each were immediately loaded in opposite direction by various forces (100, 300 or 500 cN) through tension coils. Additionally, three different distances between the neck of the implant and the bone rim (1, 2 and 3 mm) were used. The different load protocols were chosen to evaluate the load-related implant performance. The load was provided by superelastic tension coils, which are known to develop a virtually constant force. Non-loaded implants were used as a reference. Following an experimental loading period of 22 and 70 days half of the minipigs were sacrificed, and implant containing bone specimens evaluated for clinical performance and implant stability. Implant loosing was found to be statistically dependent on the tip moment (TM) at the bone rim. Clinical implant loosing were only present when load exceeded 900 cN mm. No movement of implants through the bone was found in the experimental groups, for any applied loads. Over the two experimental periods the non-loaded implants of one type of implant had a higher stability than those of the loaded implants. Dual Top® implants revealed a slightly higher removal torque compared with Abso Anchor® implants. Based on the results of this study, immediate loading of mini-implants can be performed without loss of stability when the load-related biomechanics do not exceed an upper limit of TM at the bone rim. Résumé Le but de cette étude a été de déterminer ce qui se passait cliniquement et biomécaniquement au niveau de deux systèmes de mini-implants en titane activés par différents régimes de mise en charge. Deux cents mini-implants (102 Abso Anchor® et 98 Dual Top®) ont été placés dans la mandibule de huit mini-porcs de Göttinger. Deux implants chacun ont été immédiatement mis en charge dans une direction opposée avec des forces variables (100 cN, 300 cN ou 500 cN) par des ressorts de tension. De plus trois distances différentes entre l'épaulement de l'implant et le rebord osseux (1, 2, 3 mm) ont été utilisés. Les différents protocoles de mise en charge ont été choisis pour évaluer la performance implantaire vis-à-vis de la mise en charge. Cette charge était produite par des ressorts de tension super-élastiques connues pour développer une force quasi-constante. Des implants sans charge ont servi de contrôle. Suivant une période de mise en charge de 22 et 70 jours la moitié des mini-porcs ont été euthanasiés et les spécimens comprenant l'os et l'implant évalués pour leur performance clinique et leur stabilité implantaire. La mobilité implantaire a été reconnue comme statisquement dépendante du moment de l'extrêmité au niveau du bord osseux. La mobilité implantaire clinique a seulement été rencontrée lorsque la charge dépassait 900 cN mm. Aucun mouvement des implants n'a été trouvée dans le groupe expérimental pour aucune des forces appliquées. Durant les deux périodes expérimentales les implants non-chargés d'un type d'implant avaient une stabilité supérieure à celle des implants chargés. Les implants Dual Top® avaient une force de torsion d'enlèvement un peu plus importante que les implants Abso Anchor®. La mise en charge immédiate de mini-implants peut être effectuée sans perte de stabilité lorsque la charge en relation avec la biomécanique n'excède pas une limite supérieure du moment de l'extrêmité au niveau du bord osseux. Zusammenfassung Es war das Ziel dieser Studie, die klinische und biomechanische Reaktion bei zwei verschiedenen Titan Mini-Implantat-Systemen, welche verschiedenen Belastungen ausgesetzt wurden, zu bestimmen. Insgesamt wurden 200 Mini-Implantate (102 Abso Anchor® und 98 Dual Top®) in die Unterkiefer von 8 Göttinger Minipigs eingesetzt. Immer zwei Implantate wurden jeweils sofort in entgegen gesetzter Richtung mit unterschiedlichen Kräften (100 cN, 300 cN oder 500 cN) durch Zugfedern belastet. Zusätzlich wurden drei verschiedene Abstände zwischen dem Hals des Implantats und der Knochenkante (1 mm, 2 mm, 3 mm) verwendet. Die unterschiedlichen Belastungsprotokolle wurden ausgewählt, um die belastungsbedingte Implantatreaktion auszuwerten. Die Belastung wurde mit superelastischen Zugfedern durchgeführt, welche dafür bekannt sind, dass sie eine relativ konstante Kraft entwickeln. Unbelastete Implantate dienten als Kontrolle. Nach einer experimentellen Belastungsdauer von 22 und 70 Tagen wurde je die Hälfte der Minipigs geopfert. An Knochenpräparaten mit Implantaten wurde die klinische Reaktion und die Stabilität der Implantate ausgewertet. Es wurde entdeckt, dass die Lockerung von Implantaten statistisch signifikant abhängig vom Kippmoment auf Höhe der Knochenkante war. Eine klinische Lockerung von Implantaten trat nur auf, wenn die Belastung 900 cN mm überstieg. Bei den experimentellen Gruppen konnte mit den applizierten Kräften keine Bewegung der Implantate durch den Knochen ausgelöst werden. Ueber die zwei Abschnitte des Experiments wiesen die nicht belasteten Implantate eines Typs eine grössere Stabilität als die belasteten Implantate auf. Die Dual Top® Implantate zeigten leicht höhere Ausdrehmomente als die Abso Anchor® Implantate. Aufgrund der Resultate dieser Studie kann eine Sofortbelastung von Mini-Implantaten ohne Stabilitätsverlust durchgeführt werden, sofern durch die Belastung die obere Grenze eines Kippmoments auf Höhe der Knochenkante nicht überschreitet. Resumen El propósito de este estudio fue determinar los resultados clínicos y biomecánicos de dos sistemas diferentes de mini-implantes de titanio activados con diferentes regimenes de carga. Se colocaron un total de 200 mini-implantes (102 Abso Anchor® y 98 Dual Top®) en la mandíbula de 8 minicerdos Göttinger. Se cargaron dos implantes inmediatamente en direcciones opuestas con varias fuerzas (100 cN, 300 cN o 500 cN) a través de resortes de tensión. Se usaron, adicionalmente, tres distancias diferentes entre el cuello del implante y el reborde óseo (1 mm, 2 mm, 3 mm). Los diferentes protocolos de carga se eligieron para evaluar el rendimiento relacionado con la carga. La carga se suministró por medio de resortes de tensión superelásticos, conocidos por desarrollar una fuerza virtualmente constante. Los implantes no cargados se usaron como referencia. Tras un periodo experimental de carga de 22 y 70 días la mitad de los minicerdos se sacrificaron, y se evaluaron los implantes conteniendo especímenes óseos para el rendimiento clínico y estabilidad de los implantes. El aflojamiento del implante se encontró que era estadísticamente dependiente de la punta del momento en el reborde óseo. El aflojamiento clínico del implante solo se presentó cuando la carga excedió los 900 cN mm. No se encontró movimiento de los implantes a través del hueso en los grupos experimentales, en ninguna de las cargas aplicadas. A lo largo de los dos periodos experimentales los implantes sin carga de un tipo de implante tuvieron una mayor estabilidad que aquellos de los implantes cargados. Los implantes Dual Top® necesitaron un mayor torque de remoción en comparación con los implantes Abso Anchor®. Basándose en los resultados de este estudio, la carga inmediata se puede llevar a cabo sin pérdida de estabilidad cuando la biomecánica relacionada con la carga no supere un límite superior de la punta del momento en el reborde óseo. [source] | ||||||||||