How slow is labour-based technology compared with equipment-intensive technology?

The technical content and the rate of progress for a total of 34 donor-funded feeder road projects executed between 1993 and 1997 were analysed. The results show that:

ICT Capacity as the Investment and Use of ICT: Exploring its Antecedents in Africa

In this paper, we investigate the extent to which economic, human development endowment, political, and population conditions influence information and communication technology (ICT) capacity in African nations using ordinary least squares. We use five variables to measure ICT capacity: ICT expenditure as a percent of GDP (ICTE), ICT expenditure per capita in US dollars (ICTEP), investment in telecoms with private participation (INVTE), Internet users per 100 people (INTUS), and mobile phone subscribers per 1000 people (MOBPS). Unlike ICT adoption and diffusion that focuses on the use of ICT, ICT capacity measures public and private investments in ICT and the use of ICT. The results indicate that ICT capacity of a nation increases with increased (high) corruption index. Further, ICT investment by the private sector depends mainly on human development factors and is not influenced by the perceptions of corruption about a nation. We present theoretical and practical implications of the findings for developing nations in general and African nations in particular.     

Dewatering of microalgal culture for biodiesel production: exploring polymer flocculation and tangential flow filtration

BACKGROUND: Conventional biodiesel production relies on trans‐esterification of lipids extracted from vegetable crops. However, the use of valuable vegetable food stocks as raw material for biodiesel production makes it an unfeasibly expensive process. Used cooking oil is a finite resource and requires extra downstream processing, which affects the amount of biodiesel that can be produced and the economics of the process. Lipids extracted from microalgae are considered an alternative raw material for biodiesel production. This is primarily due to the fast growth rate of these species in a simple aquaculture environment. However, the dilute nature of microalgae culture puts a huge economic burden on the dewatering process especially on an industrial scale. This current study explores the performance and economic viability of chemical flocculation and tangential flow filtration (TFF) for the dewatering of Tetraselmis suecica microalgae culture. RESULT: Results show that TFF concentrates the microalgae feedstock up to 148 times by consuming 2.06 kWh m^?3 of energy while flocculation consumes 14.81 kWh m^?3 to concentrate the microalgae up to 357 times. Economic evaluation demonstrates that even though TFF has higher initial capital investment than polymer flocculation, the payback period for TFF at the upper extreme of microalgae revenue is ～1.5 years while that of flocculation is ～3 years. CONCLUSION: These results illustrate that improved dewatering levels can be achieved more economically by employing TFF. The performances of these two techniques are also compared with other dewatering techniques. Copyright © 2009 Society of Chemical Industry     

Protein loaded mesoporous silica spheres as a controlled delivery platform

BACKGROUND: The adsorption of bovine serum albumin (BSA) onto mesoporous silica spheres (MPS) synthesized from silica colloids was studied employing real time in situ measurements. The stabilities of the BSA at different pH values, their isoelectric points and zeta potentials were determined in order to probe the interactions between the protein and the mesoporous silica. RESULTS: The pore size of MPS was designed for protein, and this, coupled with an in depth understanding of the physico‐chemical characteristics of the protein and MPS has yielded a better binding capacity and delivery profile. The adsorption isotherm at pH 4.2 fitted the Langmuir model and displayed the highest adsorption capacity (71.43 mg mL^?1 MPS). Furthermore, the delivery rates of BSA from the MPS under physiological conditions were shown to be dependent on the ionic strength of the buffer and protein loading concentration. CONCLUSION: Economics and scale‐up considerations of mesoporous material synthesized via destabilization of colloids by electrolyte indicate the scaleability and commercial viability of this technology as a delivery platform for biopharmaceutical applications. Copyright © 2007 Society of Chemical Industry     

Implementing the Lorenz oscillator with translinear elements

Nonlinear processing is often more suitable than the traditional linear approach is for analyzing biological signals. Unfortunately, digital nonlinear operations are computationaly expensive. In contrast, a large variety of nonlinear operations can efficiently be implemented in analog electronics, operating at real-time speeds. The low level of accuracy generally associated with analog processing is not a concern in this scenario, as biological signals themselves typically have low signal-to-noise ratios. One challenge of analog processing is in its apparently-ad hoc design, and the fact that there is very little wide-spread knowledge of systematically implementing analog electronics to perform arbitrary nonlinear computations. Another issue is the integrity of the analog components; the analog properties of electronic devices are prone to a large amount of mismatch. In this paper, we examine multiple-input translinear element (MITE) networks, a class of analog circuits that addresses the two concerns of a structured synthesis procedure and component mismatch. We test the ability of these MITE networks for accurately realizing linear and nonlinear systems with prescribed dynamics by attempting to implement the Lorenz equations. We will present the theoretical procedure, address practical implementation issues, and then show experimental results from a version of the circuit fabricated in a 0.5 μm CMOS technology through MOSIS.     

Evaluating ‘new’ instrumentation and control technologies for safety-related applications in nuclear power plants

As obsolescence and spare parts issues drive nuclear power plants to upgrade with new technologies (such as optical fiber communication systems), the ability of the new technologies to withstand environmental stresses that act at the installation location needs to be determined. New standards may be required to address environmental qualification and their application to the nuclear power plants of tommorow. This article discusses the failure modes and age-related degradation mechanisms relevant to fiber-optic communication systems in particular, and suggests a methodology for identifying conditions under which accelerated aging should be performed during qualification testing. While optical fiber communication systems have been used as the basis for discussion, the methodology presented should be applicable to any safety-related instrumentation and control equipment not covered under Title 10 of the Code of Federal Regulations (10 CFR 50.49).     

A microphone readout interface with 74-dB SNDR

A continuous-time (CT) sigma-delta modulator (SDM) for condenser microphone readout interfaces is presented in this paper. The CT SDM can accommodate a single-ended input and has high input impedance, so that it can be directly driven by a single-ended condenser microphone. A current-sensing boosted OTA-C integrator with capacitive feedforward compensation is employed in the CT SDM to achieve high input impedance and high linearity with low power consumption. Fabricated in a \(0.35\) - \(\upmu\) m complementary metal-oxide-semiconductor (CMOS) process, a circuit prototype of the CT SDM achieves a peak signal-to-noise-and-distortion ratio of 74.2 dB, with 10-kHz bandwidth and \(801\) - \(\upmu\) W power consumption.     

Scattering matrix interpolation from the perturbation method: application to calculation of a grating's electromagnetic and scatterometric signatures

The scatterometric and electromagnetic signatures of a pattern are computed with the perturbation method combined with the Fourier modal method in order to reduce computational time. From an electromagnetic point of view, the grating is characterized by its scattering matrix, which allows the computation of the reflection and transmission coefficients. A slight variation of profile parameters or electrical ones provides a small fluctuation of the scattering matrix; consequently, an analytical expression of the local behavior of its eigenvectors and eigenvalues can be obtained by using a perturbation method.