John Davidson came to the North Carolina back country circa 1751 as a young man, with his sister and widowed mother. Typical of Scots-Irish settlers, they arrived with little more than basic farming ...tools, determined to make it on their own terms. Davidson worked hard, prospered, married well and built a plantation on the Catawba River he called Rural Hill. The Davidson's were loyal British citizens who paid their taxes and participated in colonial government. When the Crown's overbearing authority interfered, independence became paramount and Davidson and his neighbors became soldiers in the Revolutionary War. After the war Davidson managed his plantation, created shad fisheries, helped develop the local iron industry with his sons-in-law and was an early planter of cotton. His sons and grandsons, along with their slave families, continuously increased and improved the acreage and became early practitioners of scientific farming.Drawing on public documents, family papers and slave records, this history describes how a fiercely independent family grew their lands and fortunes into a lasting legacy.
Environments that are hostile to life are characterized by reduced microbial activity which results in poor soil- and plant-health, low biomass and biodiversity, and feeble ecosystem development. ...Whereas the functional biosphere may primarily be constrained by water activity (aw) the mechanism(s) by which this occurs have not been fully elucidated. Remarkably we found that, for diverse species of xerophilic fungi at aw values of less-than or equal to 0.72, water activity per se did not limit cellular function. We provide evidence that chaotropic activity determined their biotic window, and obtained mycelial growth at water activities as low as 0.647 (below that recorded for any microbial species) by addition of compounds that reduced the net chaotropicity. Unexpectedly we found that some fungi grew optimally under chaotropic conditions, providing evidence for a previously uncharacterized class of extremophilic microbes. Further studies to elucidate the way in which solute activities interact to determine the limits of life may lead to enhanced biotechnological processes, and increased productivity of agricultural and natural ecosystems in arid and semiarid regions.
SEAFOOD "GARDENS" WILLIAMS, JIM
Journal of the Polynesian Society,
12/2016, Letnik:
125, Številka:
4
Journal Article
Recenzirano
Odprti dostop
This article reviews seafood gardening by Ngāi Tahu, including seeding, habitat enhancement, species improvement and marine storage. It is argued that a regime of management practises certainly ...justifies the term "gardening", as has been argued for similar practises elsewhere (in particular, the American Pacific coast).
Constraining global average temperatures to 2 °C above pre-industrial levels will probably require global energy system emissions to be halved by 2050 and complete decarbonization by 2100. In the ...nationally orientated climate policy framework codified under the Paris Agreement, each nation must decide the scale and method of their emissions reduction contribution while remaining consistent with the global carbon budget. This policy process will require engagement amongst a wide range of stakeholders who have very different visions for the physical implementation of deep decarbonization. The Deep Decarbonization Pathways Project (DDPP) has developed a methodology, building on the energy, climate and economics literature, to structure these debates based on the following principles: country-scale analysis to capture specific physical, economic and political circumstances to maximize policy relevance, a long-term perspective to harmonize short-term decisions with the long-term objective and detailed sectoral analysis with transparent representation of emissions drivers through a common accounting framework or 'dashboard'. These principles are operationalized in the creation of deep decarbonization pathways (DDPs), which involve technically detailed, sector-by-sector maps of each country's decarbonization transition, backcasting feasible pathways from 2050 end points. This article shows how the sixteen DDPP country teams, covering 74% of global energy system emissions, used this method to collectively restrain emissions to a level consistent with the 2 °C target while maintaining development aspirations and reflecting national circumstances, mainly through efficiency, decarbonization of energy carriers (e.g. electricity, hydrogen, biofuels and synthetic gas) and switching to these carriers. The cross-cutting analysis of country scenarios reveals important enabling conditions for the transformation, pertaining to technology research and development, investment, trade and global and national policies.
Policy relevance
In the nation-focused global climate policy framework codified in the Paris Agreement, the purpose of the DDPP and DDPs is to provide a common method by which global and national governments, business, civil society and researchers in each country can communicate, compare and debate differing concrete visions for deep decarbonization in order to underpin the necessary societal and political consensus to design and implement short-term policy packages that are consistent with long-term global decarbonization.
The formation of fine secondary hexagonal close packed (HCP) α-Ti precipitates provides major strengthening in a new Ti-6Al-5Fe-0.05B-0.05C (mass fractions in pct) cast alloy. The phase ...transformation mechanisms from the body-centered cubic (BCC) β-Ti matrix to fine α phase in this new α-β titanium alloy were investigated experimentally and computationally using CALculation of PHAse Diagram (CALPHAD)-based thermodynamic and kinetic models. The discrete distribution of α precipitates was observed in the as-cast alloy with evidence of strong Fe partitioning. Two main size groups of α precipitates and the Fe partitioning were characterized using scanning electron microscopy, scanning transmission electron microscopy, and synchrotron-based small-angle X-ray scattering techniques. A hypothesis of Fe-partitioning driven α precipitate nucleation and growth was validated by precipitation simulation using TC-PRISMA with customized thermodynamic and kinetic descriptions. These results suggested a new titanium alloy design route involving high-mobility elements (enhancing fine secondary α precipitates) and demonstrated the capability of CALPHAD-based modeling in titanium alloy design.
Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms of solute tolerance. Whereas the most halophilic prokaryotes are known ...for an ability to multiply at saturated NaCl (water activity (a(w)) 0.755) some xerophilic fungi can germinate, usually at high-sugar concentrations, at values as low as 0.650-0.605 a(w). Here, we present evidence that halophilic prokayotes can grow down to water activities of <0.755 for Halanaerobium lacusrosei (0.748), Halobacterium strain 004.1 (0.728), Halobacterium sp. NRC-1 and Halococcus morrhuae (0.717), Haloquadratum walsbyi (0.709), Halococcus salifodinae (0.693), Halobacterium noricense (0.687), Natrinema pallidum (0.681) and haloarchaeal strains GN-2 and GN-5 (0.635 a(w)). Furthermore, extrapolation of growth curves (prone to giving conservative estimates) indicated theoretical minima down to 0.611 aw for extreme, obligately halophilic Archaea and Bacteria. These were compared with minima for the most solute-tolerant Bacteria in high-sugar (or other non-saline) media (Mycobacterium spp., Tetragenococcus halophilus, Saccharibacter floricola, Staphylococcus aureus and so on) and eukaryotic microbes in saline (Wallemia spp., Basipetospora halophila, Dunaliella spp. and so on) and high-sugar substrates (for example, Xeromyces bisporus, Zygosaccharomyces rouxii, Aspergillus and Eurotium spp.). We also manipulated the balance of chaotropic and kosmotropic stressors for the extreme, xerophilic fungi Aspergillus penicilloides and X. bisporus and, via this approach, their established water-activity limits for mycelial growth (∼0.65) were reduced to 0.640. Furthermore, extrapolations indicated theoretical limits of 0.632 and 0.636 a(w) for A. penicilloides and X. bisporus, respectively. Collectively, these findings suggest that there is a common water-activity limit that is determined by physicochemical constraints for the three domains of life.
Silicon has several technologically promising allotropes that are formed via high-pressure synthesis. One of these phases (hd) has been predicted to have a direct band gap under tensile strain, ...whereas other (r8 and bc8) phases are predicted to have narrow band gaps and good absorption across the solar spectrum. Pure volumes of these phases cannot be made using conventional nanowire growth techniques. In this work, Si nanowires were compressed up to ∼20 GPa and then decompressed using a diamond anvil cell in the temperature range of 25–165 °C. It was found that at intermediate temperatures, near-phase-pure bc8-Si nanowires were produced, whereas amorphous Si (a-Si) dominated at lower temperatures, and a direct transformation to the diamond cubic phase (dc-Si) occurred at higher temperatures under compression. Thus this study has opened up a new pressure–temperature pathway for the synthesis of novel Si nanowires consisting of designed phase components with transformative properties.
Abstract
In recent years, infrared photodetectors using silicon hyperdoped with deep-level dopants started to demonstrate extended light detection beyond the silicon’s absorption edge. The reported ...responsivities or external quantum efficiencies, however, are typically low. Focusing on gold-hyperdoped silicon and using time-resolved terahertz spectroscopy, a non-contact photoconductivity measurement, we investigated how hyperdoping parameters affect charge carrier lifetimes. Correlating the observed lifetime characteristics with dopant distribution profiles, we identify factors that impact carrier lifetime most significantly. Specifically, the charge carrier lifetime reduces with increasing gold concentrations, increasing ion implantation energies, and increasing pulsed-laser melting fluences. Both ion implantation energy and laser fluence affect the dopant incorporation depths. The total gold dose implanted and laser fluence affect the carrier distribution profile, particularly the concentration spike toward the surface. Oxide passivation and the number of laser pulses do not impact the carrier lifetime significantly. Our findings benefit future device developments.
This book is far more than just another tutorial or reference guide - it's a tour through the world of analog design, combining theory and applications with the philosophies behind the design ...process. Readers will learn how leading analog circuit designers approach problems and how they think about solutions to those problems. They'll also learn about the `analog way' - a broad, flexible method of thinking about analog design tasks. * A comprehensive and useful guide to analog theory and applications * Covers visualizing the operation of analog circuits * Looks at how to rapidly determine workable approximations of analog circuit parameters
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