In this thesis I study the impact of electrification using solar photovoltaic panels in the rural Ecuadorian community of Las Balsas. Many large-scale development organizations like the World Bank promote small-scale renewable energy technologies like solar photovoltaics as being crucial in helping poor rural communities generate more income. My research however, both in the field and in the literature, shows income generation from these projects tends to be minimal. I find that the introduction of solar electrification is most important for social applications like music, movies, cell phones, and lighting. FEDETA, the NGO that installed the solar photovoltaics, promotes the development project not as a neoliberal market-based income-generation project, but rather as a humanistic improvement in the “quality of life” of local residents. I analyze this goal of the project in light of the development theories developed over the past few decades. I question how well solar photovoltaics fits into the “small is beautiful” appropriate technology sector. While solar photovoltaic systems have the potential to build small-scale islands of autonomous electricity production in a more environmentally sustainable manner than grid electricity based on fossil fuels, I caution that this is not necessarily the most equitable way to provide electricity to the rural poor in developing countries. While solar home systems have much potential to provide (often minimal amounts of) electricity to extremely rural areas, the service provided is in many cases inferior to grid electricity. While solar photovoltaic technology does provide many potential benefits in areas not reached by grid electricity, NGOs and policy makers should be wary of seeing the technology as a panacea for sustainable development. Solar photovoltaics as a technology has a long way to go to provide energy services comparable to that offered by most grid systems. As with any technology its actual use is not predetermined, but rather is influenced by the local social and cultural contexts. / text

No description available.

In this work, the main emphasis of the research concerns the development of isolation and purification methods of biomolecules from biological fluids. Several separation techniques were incorporated in chromatographic gels to obtain multifunctional hybrid chromatographic separation media for proteins, peptides and amino acid isolation and purification.In the first part of the research, several chelating agents were synthesized and their effectiveness to purify immunoglobulins using Immobilized Metal Affinity Chromatography (IMAC) was investigated. Ethylenediamine triacetic acid (TED) with immobilized copper resulted in the most effective in terms of purification and protein capacities.The next part of the work involved the development of hybrid chromatographic media that combines protein specific adsorption with sharp controlled size access permeation. This was accomplished by incorporating two types of ligand derivatives, one that permits the permeation of only certain molecular size range compounds, and a second one that specifically binds target biomolecules among the compounds of that specific molecular size range. Hybrid systems included binding ligands for Immobilized Metal Affinity Chromatography (IMAC), Ion Exchange Chromatography (IEX) and Hydrophobic Interaction Chromatography (HIC) combined with a controlled access polymer at different densities such as polyethylene glycol (PEG) and dextran derivatives. In general, low grafting density of high molecular weight PEG was found to be as effective as high grafting density of low molecular weight PEG in the rejecting properties of the semi-permeable synthesized media.Theoretical and experimental batch adsorption studies were also performed with the hybrid media and a mathematical model was developed to study the uptake of proteins under specific conditions of controlled permeation.In the last stage of this work, chelating surfactants were synthesized and used as reversible affinity ligands on reversed phase adsorbents for protein separations.One of the main accomplishments of this research was the development of separation media for small molecular size compounds from larger molecules and from complex biological systems. Applications of special interest will include the isolation and purification of solutes, such as metal ions, toxins, drugs, biomolecules, including proteins, biotoxins, nucleic acids, peptides, hormones, and biomarkers from biological fluids (such as human serum, urine, etc.) and from aqueous solutions.

No description available.

No description available.

No description available.

No description available.

No description available.

The objective of this research is to develop a Markovian model in the form of a discrete-time queueing network to assess the performance of random access code division multiple access networks (CDMA). An approximation method called equilibrium point analysis (EPA) has been used to solve the model. The CDMA protocol IS an important application of spread spectrum communications that allows simultaneous transmission of multiple users to occupy a wideband channel with small interference. This is done by assigning each user a unique pseudo noise code sequence. These codes have low cross-correlation between each pair of sequences. Both slotted direct sequence CDMA (DS) and frequency hopping CDMA (FH) are considered with an emphasis on DS-CDMA systems. The EPA method has previously been used to evaluate the performance of other random access systems such as the ALOHA protocol, but has not previously been used in the context of a CDMA protocol. Throughput and mean packet delay of random access CDMA networks are evaluated, since these two measures are usually used in the study of the performance assessment of mUltiple access protocols. The analytical results of the random access model are validated against a discrete-event simulation which is run for large number of slots. The study then proceeds by using the model to examine the effect on performance of introducing error correcting codes to the DS-CDMA systems. Optimum error correcting codes that give the best performances in terms of the throughput and the delay are determined. The perfonnance of random access CDMA systems applied to radio channels, as in packet radio networks, is then studied, and the effect of multipath fading on the perfonnance is evaluated. Finally, the perfonnance of DS-CDMA with different user classes (non-identical users case) is investigated. An extended equilibrium point analysis (EEPA) method has been used to solve the Markovian model in this situation. This extended model is used to assess the effects on perfonnance of the unequal powers due to varying distances of the users to an intended receiver or to a base station (near-far problem).

Although having conscious experiences is a fundamental feature of our everyday life, our understanding of what consciousness is is very limited. According to one of the main conclusions of contemporary philosophy of mind, the qualitative aspect of consciousness seems to resist functionalisation, i.e. it cannot be adequately defined solely in terms of functional or causal roles, which leads to an epistemic gap between phenomenal and scientific knowledge. Phenomenal qualities, then, seem to be, in principle, unexplainable in scientific terms. As a reaction to this pessimistic conclusion it is a major trend in contemporary science of consciousness to turn away from subjective experiences and re-define the subject of investigations in neurological and behavioural terms. This move, however, creates a gap between scientific theories of consciousness, and the original phenomenon, which we are so intimately connected with. The thesis focuses on this gap. It is argued that it is possible to explain features of consciousness in scientific terms. The thesis argues for this claim from two directions. On the one hand, a specific identity theory is formulated connecting phenomenal qualities to certain intermediate level perceptual representations which are unstructured for central processes of the embedding cognitive system. This identity theory is hypothesised on the basis of certain similarities recognised between the phenomenal and the cognitive-representational domains, and then utilised in order to uncover further similarities between these two domains. The identity theory and the further similarities uncovered are then deployed in formulating explanations of the philosophically most important characteristics of the phenomenal domain—i.e. why phenomenal qualities resist functionalisation, and why the epistemic gap occurs. On the other hand, the thesis investigates and criticises existing models of reductive explanation. On the basis of a detailed analysis of how successful scientific explanations proceed a novel account of reductive explanation is proposed, which utilises so-called prior identities. Prior identities are prerequisites rather than outcomes of reductive explanations. They themselves are unexplained but are nevertheless necessary for mapping the features to be explained onto the features the explanation relies on. Prior identities are hypothesised in order to foster the formulation of explanatory claims accounting for target level phenomena in terms of base level processes—and they are justified if they help projecting base level explanations to new territories of the target level. The thesis concludes that the identity theory proposed is a prior identity, and the explanations of features of the phenomenal domain formulated with the aid of this identity are reductive explanations proper. In this sense, the thesis introduces the problem of phenomenal consciousness into scientific discourse, and therefore offers a bridge between the philosophy and the science of consciousness: it offers an approach to conscious experience which, on the one hand, tries to account for the philosophically most important features of consciousness, whereas, on the other hand, does it in a way which smoothly fits into the everyday practice of scientific research.