531 research outputs found
A dynamic simulation of low-carbon policy influences on endogenous electricity demand in an isolated island system
This paper considers the dynamics of electricity demand in response to changes arising from low-carbon policies and socio-economic developments. As part of an investigation into the evolution of such systems on small economically-developed islands, endogenous electricity demand and associated policies are studied for the Azorean island of São Miguel. A comprehensive System Dynamics (SD) model covering the period 2005 − 2050 is presented which captures both historical behaviours and real-world influences on the endogenous demand dynamics of an island-based electricity system. The impact of tourism, energy efficiency and electric vehicles (EV) expansion allied with associated policy options, are critically evaluated by the SD model using a series of scenarios. The model shows that energy efficiency measures exhibit the most significant long-term impact on electricity demand, while in contrast, policies to increase tourism have a much less direct impact and EV expansion has thought-provoking impacts on the long-term demand, although this is not as influential as energy efficiency measures
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Insights into the Thermal Generation Futures of Isolated Island Electricity Systems Using System Dynamics
In future, long-term thermal generation investments will be greatly influenced by the best available mixes of legacy fossil fuels and renewable sources. Intuitively, a detailed first look at the dynamics which surrounds thermal investments will assist policy makers in shaping optimally required generation mixes. To achieve this, a system dynamics model of an isolated island electricity system was developed. This model gauges the long-term investment decisions that can exist within such systems. It addresses the thermal capacity additions and the extent to which financially influenced and demand growth influenced additions affects the long-term stability of the system. Reflecting a reality typical of island systems, this model does not have a supply and demand driven pricing mechanism and thus adopts exogenous electricity tariffs. It however accounts endogenously for changes in the thermal capacity margins and capacity costing. The case study used considers the Azorean island of Sao Miguel; which provides a background for the model and is used for testing its ability to capture various aspects of historical behaviors and real-world influences on the long-term thermal generation decisions. The paper concludes with a discussion of the investment decision insights gained and the possible future extensions, uses and modifications of the model
Statistical Communication Theory
Contains research objectives and reports on three research projects
Evidence for D1 Dopamine Receptor Activation by a Paracrine Signal of Dopamine in Tick Salivary Glands
Ticks that feed on vertebrate hosts use their salivary secretion, which contains various bioactive components, to manipulate the host's responses. The mechanisms controlling the tick salivary gland in this dynamic process are not well understood. We identified the tick D1 receptor activated by dopamine, a potent inducer of the salivary secretion of ticks. Temporal and spatial expression patterns examined by immunohistochemistry and reverse transcription polymerase chain reaction suggest that the dopamine produced in the basal cells of salivary gland acini is secreted into the lumen and activates the D1 receptors on the luminal surface of the cells lining the acini. Therefore, we propose a paracrine function of dopamine that is mediated by the D1 receptor in the salivary gland at an early phase of feeding. The molecular and pharmacological characterization of the D1 receptor in this study provides the foundation for understanding the functions of dopamine in the blood-feeding of ticks
Teaching Medicine to Non-English Speaking Background Learners in a Foreign Country
Teaching abroad exposes medical educators to unfamiliar teaching methods and learning styles that can enhance their overall teaching repertoire. Based on the author’s experience teaching residents for one month at a community hospital in Japan and a review of the non-English speaking background (NESB) educational literature, pedagogical principles and lessons for successful international NESB instruction are outlined. These methods include understanding the dissimilar linguistic, cultural, and academic backgrounds of the learners, emphasizing pace and clarity of speech, presenting a conceptual framework instead of detailed discourse on subjects, and regular visual reinforcement of spoken words. The limitations introduced by the language barrier and the use of interpreters are briefly discussed. As society and institutions of higher learning become more global and multicultural, clinician–educators may benefit from teaching in other countries in order to enhance their teaching skills with NESB learners, both abroad and in their own institutions
Immunity against Ixodes scapularis Salivary Proteins Expressed within 24 Hours of Attachment Thwarts Tick Feeding and Impairs Borrelia Transmission
In North America, the black-legged tick, Ixodes scapularis, an obligate haematophagus arthropod, is a vector of several human pathogens including Borrelia burgdorferi, the Lyme disease agent. In this report, we show that the tick salivary gland transcriptome and proteome is dynamic and changes during the process of engorgement. We demonstrate, using a guinea pig model of I. scapularis feeding and B. burgdorferi transmission, that immunity directed against salivary proteins expressed in the first 24 h of tick attachment — and not later — is sufficient to evoke all the hallmarks of acquired tick-immunity, to thwart tick feeding and also to impair Borrelia transmission. Defining this subset of proteins will promote a mechanistic understanding of novel I. scapularis proteins critical for the initiation of tick feeding and for Borrelia transmission
Tick Histamine Release Factor Is Critical for Ixodes scapularis Engorgement and Transmission of the Lyme Disease Agent
Ticks are distributed worldwide and affect human and animal health by transmitting diverse infectious agents. Effective vaccines against most tick-borne pathogens are not currently available. In this study, we characterized a tick histamine release factor (tHRF) from Ixodes scapularis and addressed the vaccine potential of this antigen in the context of tick engorgement and B. burgdorferi transmission. Results from western blotting and quantitative Reverse Transcription-PCR showed that tHRF is secreted in tick saliva, and upregulated in Borrelia burgdorferi-infected ticks. Further, the expression of tHRF was coincident with the rapid feeding phase of the tick, suggesting a role for tHRF in tick engorgement and concomitantly, for efficient B. burgdorferi transmission. Silencing tHRF by RNA interference (RNAi) significantly impaired tick feeding and decreased B. burgdorferi burden in mice. Interfering with tHRF by actively immunizing mice with recombinant tHRF, or passively transferring tHRF antiserum, also markedly reduced the efficiency of tick feeding and B. burgdorferi burden in mice. Recombinant tHRF was able to bind to host basophils and stimulate histamine release. Therefore, we speculate that tHRF might function in vivo to modulate vascular permeability and increase blood flow to the tick bite-site, facilitating tick engorgement. These findings suggest that blocking tHRF might offer a viable strategy to complement ongoing efforts to develop vaccines to block tick feeding and transmission of tick-borne pathogens
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