An Inquiry into the Nature and Causes of Nigeria’s Rapid Urban Transition

Owing to the dramatic pace and scale of its transformation, Nigeria is considered Africa’s next urban giant. Between 1960 and 2010, Nigeria added approximately 62.5 million inhabitants to its urban population, with forecasts to 2050 projecting an additional 226 million. As Nigeria forges ahead into the next chapter of its urban transition, there is an unmet need to take stock of past experiences, identify trends, and speculate on future growth trajectories. Taking advantage of recently available datasets from the United Nations and the Africapolis Project, this paper launches an inquiry into the nature and causes of Nigeria’s rapid urban transition between 1960 and 2010. It disaggregates urbanization into its individual components of urban growth and calculates their contributions to the overall urban increment. Several notable findings are highlighted. Nigeria, which is considered a late urbanizer, is currently in the accelerated stage of its urban transition and is projected to enter the terminal stage by 2030. Urban natural population increase has been the dominant component of urban growth in the post-colonial period and will likely continue to be so in the immediate future. Despite this, policies aimed at stemming rural to urban migration appear to have been the preferred mechanism for lessening the pressures posed by the contemporary urban transition, suggesting a potential policy mismatch.     

Accuracy of the diffusion approximation in determining the optical properties of a two-layer turbid medium

We have examined the possibility of determining the optical properties of a two-layer medium by using a diffusion approximation radiation transport model [Appl. Opt. 37, 779 (1998)]. Continuous-wave and frequency-domain (FD) low-noise Monte Carlo (MC) data were fitted to the model. Marquardt-Levenberg and a simulated annealing algorithm were used and compared as optimization techniques. Our particular choice of optical properties for the two-layer model was consistent with skin and underlying fat in the presence of an exogenous chromophore [Appl. Opt. 37, 1958 (1998)]. The results are therefore specific to this set of optical properties. It was found that the cw diffusion solution could never be used to estimate all optical properties reliably. The combined cw and FD solutions could not be used to estimate some of the top-layer optical properties to an accuracy of better than 10%, although the absorption and the transport scattering coefficients of the bottom layer could be estimated to within 7% and 0.5%, respectively. No improvement was found from simultaneously fitting MC data at three different modulation frequencies. These results point to the need for a more accurate radiation transfer model at small source-detector separations.     

Identification and characterisation of a human calmodulin-stimulated phosphodiesterase PDE1B1

A cDNA encoding a calmodulin-stimulated 3',5'-cyclic nucleotide phosphodiesterase (PDE) was isolated from a human brain cDNA library. The cDNA, designated HSPDE1B1, encoded a protein of 536 amino acids that shared 96% sequence identity with the bovine "63 kDa" calmodulin-stimulated PDE. The recombinant protein had cyclic nucleotide phosphodiesterase activity that was stimulated approximately 2-fold by Ca2+/calmodulin and preferred cGMP as substrate. In addition, the enzymatic activity of HSPDE1B1 was inhibited by phosphodiesterase inhibitors with potencies similar to that displayed toward the bovine PDE1 enzymes: IBMX approximately equal to 8-methoxymethyl-IBMX > vinpocetine approximately equal to zaprinast > cilostamide > rolipram. HSPDE1B1 mRNA was found predominantly in the brain. Lower mRNA levels were found in heart and skeletal muscle. In situ hybridisation of brain revealed expression of HSPDE1B1 predominately in neuronal cells of the cerebellum, hippocampus and caudate. The HSPDE1B1 gene was mapped to human chromosome 12. A partial genomic sequence of HSPDE1B1 was isolated and shown to contain two splice junctions that are conserved in the rat PDE4 and the Drosophila dunce genes.     

Mobolic: An automated approach to exercising mobile application GUIs using symbiosis of online testing technique and customated input generation

The increasingly prevalent use of mobile devices has raised the popularity of mobile applications. Therefore, automated testing of mobile applications has become an extremely important task. However, it is still a challenge to automatically generate tests with high coverage for mobile applications due to their specific nontrivial structure and the highly interactive nature of graphical user interfaces (GUIs). In this paper, we propose a novel automated GUI testing technique for mobile applications, namely, Mobolic. In this approach, tests with high coverage are automatically generated and executed by combining the online testing technique and customated input generation. Employing the online testing technique, Mobolic systematically explores the app GUI without falling in a loop. It generates relevant events “on the fly” that are followed by an immediate execution. In addition, involving the customated input generation, Mobolic automatically generates relevant user inputs such as user‐predefined, concrete, or random ones. We implemented Mobolic and evaluated its performance on 10 real‐world open‐source Android applications. Our experimental results show the effectiveness and efficiency of Mobolic in terms of achieved code coverage and overall exercising time.     

Novel Approach for Automatic Region of Interest and Seed Point Detection in CT Images Based on Temporal and Spatial Data

Accurately finding the region of interest is a very vital step for segmenting organs in medical image processing. We propose a novel approach of automatically identifying region of interest in Computed Tomography Image (CT) images based on temporal and spatial data . Our method is a 3 stages approach, 1) We extract organ features from the CT images by adopting the Hounsfield filter. 2)We use these filtered features and introduce our novel approach of selecting observable feature candidates by calculating contours’ area and automatically detect a seed point. 3) We use a novel approach to track the growing region changes across the CT image sequence in detecting region of interest, given a seed point as our input. We used quantitative and qualitative analysis to measure the accuracy against the given ground truth and our results presented a better performance than other generic approaches for automatic region of interest detection of organs in abdominal CT images. With the results presented in this research work, our proposed novel sequence approach method has been proven to be superior in terms of accuracy, automation and robustness.     

Space-time topology optimization for additive manufacturing

Structural and Multidisciplinary Optimization - A general method of lifetime distribution selection for multi-level complete and censored testing data is developed. To alleviate the scarcity of...     

Analysis of changes in optical fibers during arc-fusion splicing by use of quantitative phase imaging

A non-interferometric imaging technique in conjunction with Abel inversion is used to directly and quantitatively examine the changes in optical fibers due to the heating produced during arc-fusion splicing as a function of fusion arc parameters. Phase images in the vicinity of a fusion splice are obtained using Quantitative Phase Microscopy, allowing the refractive-index change to be reconstructed with high spatial resolution. This simple, nondestructive method confirms that, for a fixed arc current, while the fusion time increases, the refractive-index of both fiber cores within the fusion region decreases in magnitude, the core region broadens, and the axial gradient decreases.     

Learning to live in a smart home

ABSTRACT

Smart homes promise to significantly enhance domestic comfort, convenience, security and leisure whilst simultaneously reducing energy use through optimized home energy management. Their ability to achieve these multiple aims rests fundamentally on how they are used by householders, yet very little is currently known about this topic. The few studies that have explored the use of smart homes have tended to focus on special-interest groups and be quite short-term. This paper reports on new in-depth qualitative data that explore the domestication of a range of smart home technologies in 10 households participating in a nine-month field trial. Four core themes emerge: (1) smart home technologies are both technically and socially disruptive; (2) smart homes require forms of adaptation and familiarization from householders that can limit their use; (3) learning to use smart home technologies is a demanding and time-consuming task for which there is currently very little support available; and (4) there is little evidence that smart home technologies will generate substantial energy savings and, indeed, there is a risk that they may generate forms of energy intensification. The paper concludes by discussing the implications of these findings for policy, design and further research.     

Product development, innovation networks, infrastructure and agglomeration economies

The continuos inflow of new products is a fundamental condition for a well-functioning market economy. It has been argued that new products are the outcome of a process which is based upon the principle “novelty by combination”. This characterization applies well to the type of product development analyzed in this paper, which comprises the development of new products and the renewal of old products in the Swedish engineering industry through the adoption of a specific type of innovation, namely the incorporation of information technology based components and their pertinent software, i.e. microelectronics. According to the theoretical perspective presented in the paper, a new or a renewed product may result from “random collisions” or from a cautious matching between technical opportunities and customer needs. A necessary condition for such “collisions” or matching to occur is communication and, hence, communication in innovation networks is one key factor in product development. The empirical part of the paper contains an empirical test of the role of establishment characteristics, innovation networks, infrastructure endowment and agglomeration economies for the first use of micro-electronics in product development at the plant level. The empirical results seem to confirm the importance of innovation networks as well as of infrastructure endowment and agglomeration economies for an early use of micro-electronics in product development. Received: October 1994 / Accepted in revised form: November 1996