272 research outputs found
C-projective geometry
We develop in detail the theory of (almost) c-projective geometry, a natural analogue of projective differential geometry adapted to (almost) complex manifolds. We realise it as a type of parabolic geometry and describe the associated Cartan or tractor connection. A Kähler manifold gives rise to a c-projective structure and this is one of the primary motivations for its study. The existence of two or more Kähler metrics underlying a given c-projective structure has many ramifications, which we explore in depth. As a consequence of this analysis, we prove the Yano- Obata Conjecture for complete Kähler manifolds: if such a manifold admits a one parameter group of c-projective transformations that are not affine, then it is complex projective space, equipped with a multiple of the Fubini-Study metric.</p
Economic analysis of energy efficiency measures: Tribal case studies with The Confederated Salish and Kootenai Tribes of The Flathead Reservation, The Pascua Yaqui Tribe, and The Yurok Tribe: Working paper series--04-02
The best way to reduce air pollution from the production of electricity is not to produce it in the first place. This paper presents three cases studies explaining how energy efficiency programs can be beneficial to tribes from a purely cost-saving basis, The Yurok, Flathead and Pascua Yaqui Reservations graciously provided an opportunity to investigate energy efficiency for their tribes. In each case the consumption of electricity was reduced such that a positive net present value was present following an initial capital investment. In the case of the irrigation systems on the Flathead Reservation, the savings were substantial even though no explicit savings of water was accounted for. It is estimated that tribes can reduce electricity costs by 10-50% by following energy efficiency programs. Many programs can be very simple involving small upfront capital outlays, such as changing light bulbs or installing motion sensors. The Yurok case showed a return of 7.5% after simply changing bulbs and the Pasqua Yaqui case showed a possible return of 10-80%. Other tribes could make similar investments and realize similar benefits in addition to improved air quality. The strongest recommendation from the Air Pollution Prevention Forum to tribes was to develop an energy plan. These cases show that some fairly simple analysis can make a plan very beneficial
Identification and implementation of potential energy efficiency programs in Indian Country: Working paper series--04-03
The strongest recommendation stemming from the Air Pollution Prevention forum of the Western Regional Air Partnership (WRAP) was for tribes to develop and implement energy plans. This paper provides a discussion of the benefits of any such plan and itemized a variety of components of any said plan. A brief discussion of the WRAP is presented is the framework of improving air quality. Based on the background of Jacobs (2000) and Smith (2000), the primary and secondary benefits of energy efficiency plans are then discussed. Then a series of specific recommendations are itemized. These include tribally sponsored programs, collaborative opportunities, and tribal leadership programs
Recommendations for reducing energy consumption and improving air quality through energy efficiency in Indian Country: Working paper series--04-04
The strongest recommendation stemming from the Air Pollution Prevention forum of the Western Regional Air Partnership (WRAP) was for tribes to develop and implement energy plans. This paper provides a discussion of the benefits of any such plan and itemized a variety of components of any said plan. A brief discussion of the WRAP is presented is the framework of improving air quality. Based on the background of Jacobs (2000) and Smith (2000), the primary and secondary benefits of energy efficiency plans are then discussed. Then a series of specific recommendations are itemized. These include tribally sponsored programs, collaborative opportunities, and tribal leadership programs
Metabolic responses of two pioneer wood decay fungi to diurnally cycling temperature
Decomposition of lignin-rich wood by fungi drives nutrient recycling in woodland ecosystems. Fluctuating abiotic conditions are known to promote the functioning of ecological communities and ecosystems. In the context of wood decay, fluctuating temperature increases decomposition rates. Metabolomics, in tandem with other ‘omics tools, can highlight the metabolic processes affected by experimental treatments, even in the absence of genome sequences and annotations. Globally, natural wood decay communities are dominated by the phylum Basidiomycota. We examined the metabolic responses of Mucidula mucida, a dominant constituent of pioneer communities in beech branches in British woodlands, and Exidia glandulosa, a stress-selected constituent of the same communities, in response to constant and diurnally cycling temperature. We applied untargeted metabolomics and proteomics to beech wood blocks, colonised by M. mucida or E. glandulosa and exposed to either diurnally cycling (mean 15 ± 10°C) or constant (15°C) temperature, in a fully factorial design. Metabolites and proteins linked to lignin breakdown, the citric acid cycle, pentose phosphate pathway, carbohydrate metabolism, fatty acid metabolism and protein biosynthesis and turnover were under-enriched in fluctuating, compared to stable temperatures, in the generalist M. mucida. Conversely, E. glandulosa showed little differential response to the experimental treatments. Synthesis. By demonstrating temperature-dependant metabolic signatures related to nutrient acquisition in a generalist wood decay fungus, we provide new insights into how abiotic conditions can affect community-mediated decomposition and carbon turnover in forests. We show that mechanisms underpinning important biogeochemical processes can be highlighted using untargeted metabolomics and proteomics in the absence of well-annotated genomes
4D In-Situ Microscopy of Aerosol Filtration in a Wall Flow Filter
The transient nature of the internal pore structure of particulate wall flow filters, caused by the continuous deposition of particulate matter, makes studying their flow and filtration characteristics challenging. In this article we present a new methodology and first experimental demonstration of time resolved in-situ synchrotron micro X-ray computed tomography (micro-CT) to study aerosol filtration. We directly imaged in 4D (3D plus time) pore scale deposits of TiO2 nanoparticles (nominal mean primary diameter of 25 nm) with a pixel resolution of 1.6 μm. We obtained 3D tomograms at a rate of ∼1 per minute. The combined spatial and temporal resolution allows us to observe pore blocking and filling phenomena as they occur in the filter’s pore space. We quantified the reduction in filter porosity over time, from an initial porosity of 0.60 to a final porosity of 0.56 after 20 min. Furthermore, the penetration depth of particulate deposits and filtration rate was quantified. This novel image-based method offers valuable and statistically relevant insights into how the pore structure and function evolves during particulate filtration. Our data set will allow validation of simulations of automotive wall flow filters. Evolutions of this experimental design have potential for the study of a wide range of dry aerosol filters and could be directly applied to catalysed automotive wall flow filters
Spatial variability of precipitation regimes over Turkey
Turkish annual precipitation regimes are analysed to provide large-scale perspective and redefine precipitation regions. Monthly total precipitation data are employed for 107 stations (1963–2002). Precipitation regime shape (seasonality) and magnitude (size) are classified using a novel multivariate methodology. Six shape and five magnitude classes are identified, which exhibit clear spatial structure. A composite (shape and magnitude) regime classification reveals dominant controls on spatial variability of precipitation. Intra-annual timing and magnitude of precipitation is highly variable due to seasonal shifts in Polar and Subtropical zones and physiographic factors. Nonetheless, the classification methodology is shown to be a powerful tool that identifies physically-interpretable precipitation regions: (1) coastal regimes for Marmara, coastal Aegean, Mediterranean and Black Sea; (2) transitional regimes in continental Aegean and Southeast Anatolia; and (3) inland regimes across central and Eastern Anatolia. This research has practical implications for understanding water resources, which are under ever growing pressure in Turkey
Study of focused-ion-beam–induced structural and compositional modifications in nanoscale bilayer systems by combined grazing incidence x ray reflectivity and fluorescence
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