Are Per Capita Real GDP Series in African Countries Non-stationary or Non-linear? What does Empirical Evidence Reveal?

This paper extends the applied time series literature in economic development, by testing whether the per capita real GDP time series in 27 African countries are non-stationary or non-linear and globally stationary over the relatively long period from 1960 to 2007. Using the non- linear unit root tests developed recently by Kapetanios, Shin and Snell (2003) the results show that in one-third of the countries, the series are stationary with non-linear mean reversion. Policy implications are indicated.Mean reversion, non-linear unit root tests, GDP per capita

A self excitation and control system for wind tunnel dynamic stability measurements

The paper describes the design and development of a fast acting self-excitation and control system based on the principles of regenerative and negative feedback for phase resonance testing of aerodynamic models in wind tunnels. Simulation tests and analyses using a linearized model of the drive system are carried out, and results indicate that the system would function even if the system damping becomes neutral or negative. Experiments for dynamic stability measurements show that the control system meets all specifications and performs satisfactorily even in the presence of moderate amounts of turbulence in the air flow

Reaction Between Copper Sulphide & Sulphur Trioxide

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Evolution of nocturnal temperature inversions - A numerical study

A series of numerical simulations using a one-dimensional energy balance model suggest that both the depth and the intensity of the nocturnal temperature inversion depend on surface emissivity �g and a ground cooling rate parameter β (which inthe model is a surrogate for the inverse square root of the soil thermal diffusivity), especially under calm conditions. It is found that, after a transient that may last a few hours after nominal sunset, both depth and intensity follow the classical parabolic growth law, but only under calm conditions. If the ground cools faster the transient for the inversion depth is longer and the inversion deeper. If the surface is radiatively darker, the transient is again longer but the inversion depth is lower. The temperature at the top of the inversion is not strongly influenced by �g or β, but, depending on whether the reference is taken at the surface or at screen height, the intensity of the inversion decreases (or increases) with a drop in �g; it also increases with increase in ground cooling rate but with either choice of reference temperature. With wind, the inversion may be deeper during the transient than under calm conditions, but eventually becomes both shallower and weaker, and may disappear altogether at high winds. The effect of wind is found to be negligible whenthe frictionv elocity is less than0.2 ms −1. Comparison with observations shows general qualitative agreement, but also suggests that the highly variable results reported inthe literature onin version parameters may be due to site-dependent surface characteristics whose effects, till now ignored, need explicit attentionin future field observations and models

Growth status and site quality of different seed production areas of teak (Tectona grandis L. f) in Karnataka, India

In the present study 20 SPAs of teak distributed in southern, central and northern parts of Karnataka, India are selected. Phenotypic parameters of standing trees of different SPAs were recorded. Further, seed yield was also recorded and compared with site quality and stand growth parameters. Result showed that there was a greater variation among SPAs for phenotypic growth characters as well as site quality. The overall growth of SPAs of Madikeri zone (Southern region) was found to be superior with respect to tree height, clear bole height and DBH.SPAs belonged to Dandeli (Northern region) recorded more DBH and nearly round stem. SPAs of Yallapur seed zone showed comparatively less growth over Madikeri zone. SPA of Dandeli zone recorded the more tree volume and top height, followed by SPA of Madikeri zone. Considering site quality of different SPAs, all the studied SPAs of Karnataka are growing under relatively poor site conditions. Sixteen out of twenty SPAs, nearly 80% were growing in areas with site quality classes IV and V. Interestingly, none of the studied SPAs belonged to either class I or II. Association study showed that tree height (r=0.403) and clear bole height (r=0.412) showed positive relationship with seed yield. Furthermore, site quality showed a weak positive relationship with seed yield (R2 =0.052) among SPAs indicating poor site quality could be a major factor for low seed yield. It is concluded that SPAs of Madikeri and Dandeli zones performed better in growth and stem form. Therefore, it is suggested to collect quality seeds from these seed zones

Long Term Factors of Internet Diffusion in Sub-Saharan Africa: A Panel Co- Integration Analysis

Identifying factors that influence the diffusion of the Internet is paramount for researchers as well as policy makers in articulating strategies to improve the availability and subsequent use of the Internet. Most existing empirical studies have focused on this problem by analyzing diffusion data for countries for one fixed year and identified variables affecting the Internet diffusion. These variables, generally, come from the economic, technological, policy, culture, and human capital realms. These results have provided a good “snapshot” of what factors are important towards the diffusion of the Internet and the results tend to vary for studies conducted in different time frames. This paper also addresses, the phenomenon of cross-country dependence – the economic, political, and technological environment of one country affecting other countries- into account in their analyses. This paper, for the first time in the literature, empirically identifies long-term determinants of the Internet diffusion in sub-Saharan African (SSA) countries by considering data for the period 1997-2013. It employs a recently-developed technique named “panel co-integration analysis” to model the diffusion of the internet among the SSA countries. The analysis reveals that in SSA countries, the number of telephones, the level of per capita real gross product and the extent of ruralization (conversely, the degree of urbanization) are the key long-term drivers of the diffusion of the Internet. Finally, the paper concludes with a discussion of policy implications

Larval developmental temperature and ambient temperature affect copulation duration in a seed beetle

The effects of temperature on cellular, systemic and whole-organism processes can be short-term, acting within seconds or minutes of a temperature change, or long-term, acting across ontogenetic stages to affect an organism’s morphology, physiology and behavioural phenotype. Here we examine the effect of larval development temperature on adult copulatory behaviour in the bruchid beetle, Callosobruchus maculatus. As predicted by temperature’s kinetic effects, copulation duration was longest at the lowest ambient temperature. However, where ambient temperature was fixed and developmental temperature experimentally varied, males reared at the highest temperature were least likely to engage in copulation, whilst those reared at the lowest temperature copulated for longer. Previous research has shown males reared at cooler temperatures inseminate fewer sperm. Thus, in this species longer copulations are associated with reduced sperm transfer. We argue that knowledge of preceding ontogenetic conditions will help to elucidate the causes of variation in copulatory behaviour

Changes in genetic diversity parameters in unimproved and improved populations of teak (Tectona grandis L.f.) in Karnataka state, India

Teak (Tectona grandis L. f.; family Verbanaceae) is an important plantation tree species in the tropics and in India one of the first species to be prioritized for improvement. Improvement efforts for the last 50 years have essentially concentrated on augmenting quality seed production by establishing seed production areas (SPA) and clonal seed orchards (CSO). Presently, these two form the main sources of quality planting material for teak throughout the country. However, there is no information on the genetic quality of such sources nor information on the progeny used in plantation programmes. Reports of studies based on coniferous and tropical species provide conflicting results on the impact of domestication on the genetic diversity of populations (Chaisurisri and El Kassaby 1994; Rajora 1999; Moran et al. 2000; Godt et al. 2001; Icgen et al. 2006). Also the impact of domestication on the genetic diversity of progeny populations is poorly understood (Stoehr and El-Kassaby 1997; Schmitdtling and Hiplins 1998). Such studies become pertinent not only for gauging the impact of selection on reforestation stock, but also for effective genetic conservation of existing breeding populations. We therefore address two issues in the present study: (i) the change in genetic diversity with increasing levels of improvement, and (ii) the impact of the above change on genetic diversity of progeny populations

Influence of levels of genetic diversity on fruit quality in teak (Tectona grandis L.f.)

The study on the influence of genetic diversity on the fruit emptiness and seed germination (as a measure of fruit quality) of teak populations was carried out. The populations comprised three unimproved plantations, three seed-production areas and a clonal seed orchard within Karnataka. Significant variation between the populations was observed for fruit emptiness, seed germination and Jaccard’s dissimilarity index of the parent population. Genetic dissimilarity of populations was positively correlated to fruit emptiness and negatively correlated to seed germination. It is inferred that higher genetic dissimilarity of individuals within the population results in higher flower asynchrony and close-related mating, thereby leading to higher inbreeding depression manifested in the form of higher emptiness and low germination percentage