Quality of Knowledge Technology, Returns to Production Technology and Economic Development

Presenting a discrete time version of the Romer (1986) model, this paper analyzes optimal paths in a one-sector growth model when the technology is not convex. We prove that for a given quality of knowledge technology, the countries could take-off if their initial stock of capital are above a critical level; otherwise they could face a poverty-trap. We show that for an economy which wants to take-off by means of knowledge technology requires three factors : large amount of initial knowledge, small fixed costs and a good quality of knowledge technology.Optimal Growth;optimal path;value fuction;poverty-trap;increasing returns

Feeding habits of garfish, Belone belone euxini Günther, 1866 in autumn and winter in Turkey’s south–east coast of the Black Sea

Hábitos alimentarios de la aguja, Belone belone auxini Günther, 1866 en otoño e invierno en la costa suroriental del Mar Negro, en Turquía En el estudio se examinó el contenido estomacal de Belone belone en la costa suroriental del Mar Negro durante los meses de otoño e invierno de 2010 y 2011. Las hormigas voladoras constituyeron la presa más frecuente de la dieta en otoño, mientras que en invierno fueron los peces. Otras presas que aparecen en la dieta son moluscos, crustáceos e isópodos. Las hormigas voladoras son consumidas básicamente por los machos, en especial por los más pequeños, durante el otoño.Hábitos alimentarios de la aguja, Belone belone auxini Günther, 1866 en otoño e invierno en la costa suroriental del Mar Negro, en Turquía En el estudio se examinó el contenido estomacal de Belone belone en la costa suroriental del Mar Negro durante los meses de otoño e invierno de 2010 y 2011. Las hormigas voladoras constituyeron la presa más frecuente de la dieta en otoño, mientras que en invierno fueron los peces. Otras presas que aparecen en la dieta son moluscos, crustáceos e isópodos. Las hormigas voladoras son consumidas básicamente por los machos, en especial por los más pequeños, durante el otoño.We studied the stomach content of Belone belone in the south–east Black Sea during autumn and winter months in 2010–2011. The most frequent feeding items in the diet were insects in autumn and fish in winter. Other items in the diet were mollusks, crustaceans and isopods. Flying ants were mostly consumed by male garfish, particularly the smaller fish, in autumn

Growth maximising patent lifetime

Using a vertical differentiation model of endogenous growth with stochastic R&D activity, we characterise the optimal patent lifetime a government would set in order to maximise economic growth. We show that a finite patent lifetime does exist and is unique provided that the expected rate of return from R&D is sufficiently large. Additionally, we analyse the impact of the level of competition in the R&D sector, the interest rate, the monopoly profit and the productivity parameter of research technology on this optimal patent lifetime

Cephalometric norms for the Saudi children living in the western region of Saudi Arabia: a research report

BACKGROUND: Previous studies have established specific cephalometric norms for children with different ethnic backgrounds, showing different facial features for each group. Up till now, there is a paucity of information about the cephalometric features of Saudi children living in the western region of Saudi Arabia, who have distinct social and climatic characteristics. The aim of the present study was to establish cephalometric norms for children living in the western region of Saudi Arabia. METHODS: A total of 62 lateral cephalometric radiographs of Saudis (33 females and 29 males; aged 9–12 years) having good facial proportions and Class I dental occlusion, were traced and analyzed. Using the t-test, the mean value, standard deviation and the range of 20 angular and linear variables were calculated and compared to norms of adult Saudis living in the Western region of Saudi Arabia using the t-test. Male and female groups were also compared using the t- test. RESULTS: Saudi children tend to have a significantly shorter and lower face height, a larger angle of convexity, and more proclined and protruded incisors when compared with adult Saudis (P < 0.05). There were no statistically significant differences between male and female groups. CONCLUSION: Saudi children have distinct cephalometric features, which should be used as a reference in the orthodontic treatment of young Saudi patients

New method to characterize a machining system: application in turning

Many studies simulates the machining process by using a single degree of freedom spring-mass sytem to model the tool stiffness, or the workpiece stiffness, or the unit tool-workpiece stiffness in modelings 2D. Others impose the tool action, or use more or less complex modelings of the efforts applied by the tool taking account the tool geometry. Thus, all these models remain two-dimensional or sometimes partially three-dimensional. This paper aims at developing an experimental method allowing to determine accurately the real three-dimensional behaviour of a machining system (machine tool, cutting tool, tool-holder and associated system of force metrology six-component dynamometer). In the work-space model of machining, a new experimental procedure is implemented to determine the machining system elastic behaviour. An experimental study of machining system is presented. We propose a machining system static characterization. A decomposition in two distinct blocks of the system "Workpiece-Tool-Machine" is realized. The block Tool and the block Workpiece are studied and characterized separately by matrix stiffness and displacement (three translations and three rotations). The Castigliano's theory allows us to calculate the total stiffness matrix and the total displacement matrix. A stiffness center point and a plan of tool tip static displacement are presented in agreement with the turning machining dynamic model and especially during the self induced vibration. These results are necessary to have a good three-dimensional machining system dynamic characterization