706 research outputs found
Recent Strategies in Organic Reactions Catalyzed by Phase Transfer Catalysts and Analyzed by Gas Chromatography
Gates to Gregg High Voltage Transmission Line Study
The usefulness of LANDSAT data in the planning of transmission line routes was assessed. LANDSAT digital data and image processing techniques, specifically a multi-date supervised classification aproach, were used to develop a land cover map for an agricultural area near Fresno, California. Twenty-six land cover classes were identified, of which twenty classes were agricultural crops. High classification accuracies (greater than 80%) were attained for several classes, including cotton, grain, and vineyards. The primary products generated were 1:24,000, 1:100,000 and 1:250,000 scale maps of the classification and acreage summaries for all land cover classes within four alternate transmission line routes
Provincial Merchants in Eighteenth-Century England: The ‘Great Oaks’ of Manchester
The importance of overseas trade to England’s national wealth and international reputation in the eighteenth century amplified the public discourse on the social value of merchants. Contemporary conduct books described a hierarchical occupational structure, where merchants enjoyed the highest prestige within the business community, with tradesmen and manufacturers performing distinct and progressively less valued professional functions. These conduct books focused on London, England’s premier port and the beating heart of Europe’s commodity and financial markets. Historians have also given much attention to London but have equally demonstrated the importance of merchants in the ‘outports’, whose participation in England’s foreign trade engendered significant wealth, status and political influence. This article considers a different type of eighteenth-century merchant, one based within English manufacturing regions, and one that has been largely overlooked in the historiography, not least because their businesses elided the separation of production and mercantile activities espoused by contemporary didacts. Focusing on Manchester, the article demonstrates that the town’s ‘Great Oaks’ challenged London’s commercial hegemony in a distinctive way, seeking not to replicate outport merchants’ entrepreneurial verve in risky, multilateral trades, but specialising, as both manufacturers and merchants, in exporting to commercially developed markets, where the ability to supply a precise assortment of locally produced textiles was more important than the capacity to sell imports or to provide financial services to overseas clients. Although little studied, provincial merchant communities were a general feature of the more dynamic English manufacturing regions in the years immediately before, and during the onset of, industrialisation
Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
The phase diagram of non-hydrated Na(x)CoO(2) has been determined by changing
the Na content x using a series of chemical reactions. As x increases from 0.3,
the ground state goes from a paramagnetic metal to a charge-ordered insulator
(at x=1/2) to a `Curie-Weiss metal' (around 0.70), and finally to a weak-moment
magnetically ordered state (x>0.75). The unusual properties of the state at 1/2
(including particle-hole symmetry at low T and enhanced thermal conductivity)
are described. The strong coupling between the Na ions and the holes is
emphasized.Comment: 4 pages with 3 figures, changed conten
The Deafness-Associated Mitochondrial DNA Mutation at Position 7445, Which Affects tRNASer(UCN) Precursor Processing, Has Long-Range Effects on NADH Dehydrogenase Subunit ND6 Gene Expression
The pathogenetic mechanism of the deafness-associated mitochondrial DNA (mtDNA) T7445C mutation has been investigated in several lymphoblastoid cell lines from members of a New Zealand pedigree exhibiting the mutation in homoplasmic form and from control individuals. We show here that the mutation flanks the 3' end of the tRNASer(UCN) gene sequence and affects the rate but not the sites of processing of the tRNA precursor. This causes an average reduction of ~70% in the tRNASer(UCN) level and a decrease of ~45% in protein synthesis rate in the cell lines analyzed. The data show a sharp threshold in the capacity of tRNASer(UCN) to support the wild-type protein synthesis rate, which corresponds to ~40% of the control level of this tRNA. Strikingly, a 7445 mutation-associated marked reduction has been observed in the level of the mRNA for the NADH dehydrogenase (complex I) ND6 subunit gene, which is located ~7 kbp upstream and is cotranscribed with the tRNASer(UCN) gene, with strong evidence pointing to a mechanistic link with the tRNA precursor processing defect. Such reduction significantly affects the rate of synthesis of the ND6 subunit and plays a determinant role in the deafness-associated respiratory phenotype of the mutant cell lines. In particular, it accounts for their specific, very significant decrease in glutamate- or malate-dependent O2 consumption. Furthermore, several homoplasmic mtDNA mutations affecting subunits of NADH dehydrogenase may play a synergistic role in the establishment of the respiratory phenotype of the mutant cells
Land Suitability Assessment And Precision Farming Prospects For Irrigated Maize-Soybean Intercropping In Syferkuil Experimental Farm Using Geospatial Information Technology
To maximize maize-soybean production, and ensure efficiency and sustainability in land use, there was a need to conduct an intensive qualitative land suitability assessment. The objective of the study was to digitize the University of Limpopo experimental farm map, produce expert knowledge based land suitability map, and quantify the suitable areas formaize-soybean production under irrigation. The qualitative land suitability assessment approach study was conducted over five consecutive years from 1999 at Syferkuil experimental farm, Limpopo Province, South Africa. The evaluation of land in terms of the suitability classes was based on the method described in FAO guidelines for land evaluation for irrigated agriculture. A 1:10 000 corrected scale aerial photograph of the farm was georegistered using MapInfo Professional software, with a differential global positioning system coordinates. The soils on the farm were sampled and profiles classified using South African Binomial system of soil classification. The farm was divided into suitability classes of highly suitable (S1), suitable (S2), and unsuitable (N1), and permanently unsuitable (N2) classes. Maize-soybean suitability maps were produced based on soil characteristics and crop requirements. About 16.5% of the study area was found to be suitable for maize-soybean production, and 19.7% highly suitable. Even though there was a huge area suitable for maize-soybean production, the current land use indicated that most of it has already been used for Orchards production and horticultural research. The permanently unsuitable area (60.1 %) had shallow soils dominated by stones and plinthic horizon which had a combination of properties that restrict water movement and the penetration of roots. About 3.7%, which was classified as unsuitable was characterized by deep well weathered salt affected soils with a clay textured topsoil. The results of the studyserve as a good foundation for precision farming practices with favourable environmental conservation. Geospatial information technology and soil expert knowledge are potentially powerful tools to save the land from degradation through high-quality land suitability assessment for agricultural sustainability and resource management
Plate-impact loading of cellular structures formed by selective laser melting
Porous materials are of great interest because of improved energy absorption over their solid counterparts. Their properties, however, have been difficult to optimize. Additive manufacturing has emerged as a potential technique to closely define the structure and properties of porous components, i.e. density, strut width and pore size; however, the behaviour of these materials at very high impact energies remains largely unexplored. We describe an initial study of the dynamic compression response of lattice materials fabricated through additive manufacturing. Lattices consisting of an array of intersecting stainless steel rods were fabricated into discs using selective laser melting. The resulting discs were impacted against solid stainless steel targets at velocities ranging from 300 to 700 m s-1 using a gas gun. Continuum CTH simulations were performed to identify key features in the measured wave profiles, while 3D simulations, in which the individual cells were modelled, revealed details of microscale deformation during collapse of the lattice structure. The validated computer models have been used to provide an understanding of the deformation processes in the cellular samples. The study supports the optimization of cellular structures for application as energy absorbers. © 2014 IOP Publishing Ltd
After the great inventions: technological change in UK cotton spinning, 1780–1835
This article analyses the improvement of cotton-spinning technologies in the years after the great inventions of Hargreaves, Arkwright, and Crompton. While these ‘macro-inventions’ have attracted considerable historical attention, our understanding of the major changes in types and sizes of spinning machines used in the UK between the 1780s and the onset of state-collected factory statistics in the 1830s is still largely based on the experience of high-profile firms or specific technologies and regions. A new dataset of 1,465 machinery advertisements published in newspapers in England, Scotland, and Ireland between 1780 and 1835 allows us to examine the temporal and spatial dimensions of the market for cotton-spinning machinery, the timings of transitions between different spinning machines, and increases in machine size. The article demonstrates the importance of post-invention technical improvements in the cotton industry, showing that the productivity increases associated with the initial transition from hand to machine spinning have been overstated and that larger gains were made in the ‘micro-invention’ phase, when spinning machines became larger and faster, and required fewer workers to operate them
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