Fully printed transistors employing silicon nanoparticles

Includes bibliographical references.A new device, which utilises a previously unknown two-way mode of current switching, has been developed. This is the current switching transistor, a three-terminal electronic device which exhibits a transfer resistance, in which the application of a potential or injection of charge to one terminal controls the current at either of the two remaining terminals. The development of the current switching transistor arose from a more general project focussed on printed electronics using nanoparticulate silicon, with the aim of producing fully printed transistors. All of the printed transistors produced to date have been field-effect transistors (FETs), due to the fact that printing processes are easily applicable to the planar FET architectures. The majority of the work in the area of printed FETs has so far been focussed on the use of organic semiconducting polymers to produce organic field-effect transistors (OFETs). However, research has also been undertaken regarding the use of inorganic semiconductors, including for example, transparent metal oxides, compound semiconductors and silicon. Of the active devices, the key element is the transistor. It is essential, especially for its function as an electronic switch, in enabling a wide variety of technologies. Of particular interest are its applications in digital electronics, including logic gates, memory and comparators. The ultimate goal of printed electronics is to replace conventional electronic components with their printed equivalents, which requires the use of functional inks to deliver the desired electronic properties. Printed electronic components have potential advantages over conventional discrete and integrated circuits, especially in applications in which the printed electronics form factor is more important than the absolute technical performance of the system. Furthermore, the processes of fabrication of printed devices are far simpler and more cost efficient than those of conventional devices. This is particularly true for the current switching transistor, which can be realised by a simple two layer print

The development of a cost-effective beam loss monitor for use at the K600 magnetic spectrometer at iThemba LABS

Includes abstract.Includes bibliographical references (leaves 69-70).The purpose of this work was to develop a cost-effective beam loss monitor for use at the K600 magnetic spectrometer at iThemba LABS. To this end. the commonly used materials and technologies were reviewed and photo diodes were chosen because of their low price, high performance and ready availability. Experiments have been carried out and compared to theoretical calculations. Recommendations for future developments are presented

Creating and Sharing Fedora Installation Package for Ubuntu

4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PostersOpen repositories are enterprise information systems that face ongoing challenges of maintaining low operating costs, high efficiency, and high reliability. This poster proposal presents an open source strategy to help address some of these challenges. The NSF funded NSDL Materials Digital Library Pathway (MatDL) offers a Fedora-based open repository and is moving toward using the Ubuntu distribution of Linux on all of its servers to capitalize on the advantages of Ubuntu. However, currently there is no easy way to implement Ubuntu with Fedora-based repositories. This poster describes MatDL's efforts to co-develop and host a Fedora installation package for Ubuntu.The Materials Digital Library Pathway (DUE-0532831) is supported by the National Science Foundation

Splenic anaemia: its clinical course and pathology

The Disease called 'SPLENIC ANAEMIA1 being one which has received comparatively little attention in this country, I have ventured to make it the subject of this Thesis. As far as possible, I have endeavored to base the following description, both clinical and pathological, on cases which I have had under observation during the last four years. A study of these has also enabled me to criticise the accounts given by others in some respects, for as these cases are not common, a certain amount of error has crept into what clinical records there are. The name Splenic Anaemia is a very unsatisfactory one, but any of the others which are used are even more so, and rather than suggest another which perhaps future research might show to be equally illogical,I have employed it.The following account embraces the Etiology, Symptomatology and Morbid Anatomy of Splenic Anaemia, together with a review of what literature there is. To this I have added a suggestion as to its pathogenesis drawn from a study of my own cases. At the end, will be found the clinical records of these cases, and abstracts of those observed by others

Wireless Damage Location Sensing System

A wireless damage location sensing system uses a geometric-patterned wireless sensor that resonates in the presence of a time-varying magnetic field to generate a harmonic response that will experience a change when the sensor experiences a change in its geometric pattern. The sensing system also includes a magnetic field response recorder for wirelessly transmitting the time-varying magnetic field and for wirelessly detecting the harmonic response. The sensing system compares the actual harmonic response to a plurality of predetermined harmonic responses. Each predetermined harmonic response is associated with a severing of the sensor at a corresponding known location thereof so that a match between the actual harmonic response and one of the predetermined harmonic responses defines the known location of the severing that is associated therewith

The role of tropical forests in supporting biodiversity and hydrological integrity: a synoptic overview

Conservation of high-biodiversity tropical forests is sometimes justified on the basis of assumed hydrological benefits - in particular, the reduction of flooding hazards for downstream floodplain populations. However, the"far-field"link between deforestation and distant flooding has been difficult to demonstrate empirically. This simulation study assesses the relationship between forest cover and hydrology for all river basins intersecting the world's tropical forest biomes. The study develops a consistent set of pan-tropical land cover maps gridded at one-half degree latitude and longitude. It integrates these data with existing global biogeophysical data. The study applies the Water Balance Model - a coarse-scale process-based hydrological model - to assess the impact of land cover changes on runoff. It quantifies the impacts of forest conversion on biodiversity and hydrology for two scenarios - historical forest conversion and the potential future conversion of the most threatened remaining tropical forests. A worst-case scenario of complete conversion of the most threatened of the remaining forested areas would mean the loss of another three million km2 of tropical forests. Increased annual yield from the conversion of threatened tropical forests would be less than 5 percent of contemporary yield in aggregate. However, about 100 million people - 80 million of them in floodplains - would experience increases of more than 25 percent in annual water flows. This might be associated with commensurate increases in peak flows, though further analysis would be necessary to gauge the impact on flooding. The study highlights basins in Southeast Asia, southern China, and Latin America that warrant further study.Wetlands,Forestry,Climate Change,Drylands&Desertification,Earth Sciences&GIS

PC-CUBE: A Personal Computer Based Hypercube

PC-CUBE is an ensemble of IBM PCs or close compatibles connected in the hypercube topology with ordinary computer cables. Communication occurs at the rate of 115.2 K-band via the RS-232 serial links. Available for PC-CUBE is the Crystalline Operating System III (CrOS III), Mercury Operating System, CUBIX and PLOTIX which are parallel I/O and graphics libraries. A CrOS performance monitor was developed to facilitate the measurement of communication and computation time of a program and their effects on performance. Also available are CXLISP, a parallel version of the XLISP interpreter; GRAFIX, some graphics routines for the EGA and CGA; and a general execution profiler for determining execution time spent by program subroutines. PC-CUBE provides a programming environment similar to all hypercube systems running CrOS III, Mercury and CUBIX. In addition, every node (personal computer) has its own graphics display monitor and storage devices. These allow data to be displayed or stored at every processor, which has much instructional value and enables easier debugging of applications. Some application programs which are taken from the book Solving Problems on Concurrent Processors (Fox 88) were implemented with graphics enhancement on PC-CUBE. The applications range from solving the Mandelbrot set, Laplace equation, wave equation, long range force interaction, to WaTor, an ecological simulation

How Will the Greenhouse Industry Utilize Waste Heat?

Recent regulatory and economic change encourage waste heat use in the northern United States. In this article, the value of that form of energy to growers of greenhouse crops is assessed. It is found that production of rooted floricultural crops is likely to be the dominant activity at facilities supplied with waste heat. Waste heat utilization is unlikely to cause interregional relocation of vegetable production in the U.S