68 research outputs found
Riparian buffer design tool for cropland: lotic systems
Non-Peer ReviewedRiparian areas function as a buffer between the upland and the aquatic systems. This area is
unique in its structure and the services it provides intercepting non-point source (NPS) pollution
from the upland. In some cases additional buffer width may be required or sought. Riparian
buffer strips are a beneficial management practice (BMP) eligible for cost-shared funding under
government programs. However, little information is available to assist landowners in
appropriate location or design considerations. This project aims to create a riparian buffer design
tool to be utilized on lotic (flowing water) systems in cropland settings. This tool will consist of
a flow chart and accompanying key. The flow chart along with air photographs, soils maps and
discussions with the landowner will help to determine where on the landscape a buffer should be
located. The final product will include case studies and guiding documents for technical staff to
utilize when assisting landowners with their riparian buffer strips
Multidecadal (1997-2020) telecoupling of water management for terrestrial agriculture and a marine fishery at southern Spain
Climate change is decreasing water supplies globally while water demand is rising, making water access and distribution essential for sustainability, equity, and efficiency. In response, water management has shifted towards practices that improve water efficiency. However, links between geographically separated socioecological systems, known as telecouplings, can obscure the potential consequences of water use. This study focuses on a telecoupling between terrestrial water use and marine fisheries for the period 1997 to 2020. We develop a case study in southern Spain using multidecadal time series of the Guadalquivir river’s hydrology, its estuarine community, and the European anchovy (Engraulis encrasicolus) fishery in the Gulf of Cadiz. We found that water extracted to irrigate crops decreased the river’s flow and seasonality. However, anchovies used the estuary as a nursery before recruiting to the ocean, where they were harvested. Anchovy recruitment improved when estuary hydrology matched the Guadalquivir River’s historical hydrology (i.e., high discharge and seasonality). Then using hydro-economic modeling, we explored the outcomes of different water policies on the telecoupled socioecological systems. Our models predicted that improved water efficiency incentivized agricultural expansion. In contrast, continued marine fishery yields required management values that supported the value of the marine fishery. We highlight estuaries’ critical role in driving marine systems; yet, upriver processes drive estuaries dynamics. Overall, marine-terrestrial telecouplings provide evidence that marine fisheries that rely on estuarine reliant species would benefit of water policy and management being extended beyond the water basin
Syzygies in equivariant cohomology for non-abelian Lie groups
We extend the work of Allday-Franz-Puppe on syzygies in equivariant
cohomology from tori to arbitrary compact connected Lie groups G. In
particular, we show that for a compact orientable G-manifold X the analogue of
the Chang-Skjelbred sequence is exact if and only if the equivariant cohomology
of X is reflexive, if and only if the equivariant Poincare pairing for X is
perfect. Along the way we establish that the equivariant cohomology modules
arising from the orbit filtration of X are Cohen-Macaulay. We allow singular
spaces and introduce a Cartan model for their equivariant cohomology. We also
develop a criterion for the finiteness of the number of infinitesimal orbit
types of a G-manifold.Comment: 28 pages; minor change
What is the Oxygen Isotope Composition of Venus? The Scientific Case for Sample Return from Earth’s “Sister” Planet
Venus is Earth’s closest planetary neighbour and both bodies are of similar size and mass. As a consequence, Venus is often described as Earth’s sister planet. But the two worlds have followed very different evolutionary paths, with Earth having benign surface conditions, whereas Venus has a surface temperature of 464 °C and a surface pressure of 92 bar. These inhospitable surface conditions may partially explain why there has been such a dearth of space missions to Venus in recent years.The oxygen isotope composition of Venus is currently unknown. However, this single measurement (Δ17O) would have first order implications for our understanding of how large terrestrial planets are built. Recent isotopic studies indicate that the Solar System is bimodal in composition, divided into a carbonaceous chondrite (CC) group and a non-carbonaceous (NC) group. The CC group probably originated in the outer Solar System and the NC group in the inner Solar System. Venus comprises 41% by mass of the inner Solar System compared to 50% for Earth and only 5% for Mars. Models for building large terrestrial planets, such as Earth and Venus, would be significantly improved by a determination of the Δ17O composition of a returned sample from Venus. This measurement would help constrain the extent of early inner Solar System isotopic homogenisation and help to identify whether the feeding zones of the terrestrial planets were narrow or wide.Determining the Δ17O composition of Venus would also have significant implications for our understanding of how the Moon formed. Recent lunar formation models invoke a high energy impact between the proto-Earth and an inner Solar System-derived impactor body, Theia. The close isotopic similarity between the Earth and Moon is explained by these models as being a consequence of high-temperature, post-impact mixing. However, if Earth and Venus proved to be isotopic clones with respect to Δ17O, this would favour the classic, lower energy, giant impact scenario.We review the surface geology of Venus with the aim of identifying potential terrains that could be targeted by a robotic sample return mission. While the potentially ancient tessera terrains would be of great scientific interest, the need to minimise the influence of venusian weathering favours the sampling of young basaltic plains. In terms of a nominal sample mass, 10 g would be sufficient to undertake a full range of geochemical, isotopic and dating studies. However, it is important that additional material is collected as a legacy sample. As a consequence, a returned sample mass of at least 100 g should be recovered.Two scenarios for robotic sample return missions from Venus are presented, based on previous mission proposals. The most cost effective approach involves a “Grab and Go” strategy, either using a lander and separate orbiter, or possibly just a stand-alone lander. Sample return could also be achieved as part of a more ambitious, extended mission to study the venusian atmosphere. In both scenarios it is critical to obtain a surface atmospheric sample to define the extent of atmosphere-lithosphere oxygen isotopic disequilibrium. Surface sampling would be carried out by multiple techniques (drill, scoop, “vacuum-cleaner” device) to ensure success. Surface operations would take no longer than one hour.Analysis of returned samples would provide a firm basis for assessing similarities and differences between the evolution of Venus, Earth, Mars and smaller bodies such as Vesta. The Solar System provides an important case study in how two almost identical bodies, Earth and Venus, could have had such a divergent evolution. Finally, Venus, with its runaway greenhouse atmosphere, may provide data relevant to the understanding of similar less extreme processes on Earth. Venus is Earth’s planetary twin and deserves to be better studied and understood. In a wider context, analysis of returned samples from Venus would provide data relevant to the study of exoplanetary systems
Reise nach der Insel Kreta im griechischen Archipelagus im Jahre 1817 von F.W. Sieber der Regensburger botan. Gesellschaft, der Königl. Akademie zu München, der Naturforschenden Gesellschaft zu Paris correspondirendem und der russisch Kais. Akad. zu Mosca
Dedication:Content description: TitleIllustration: 11(Maps ,Views ,portraits ,antiquities ,)Pagination: PP22+548P+PP2+328PVolumes: 2Edition:1stText Genre:ProseIllustration: 11(χάρτες ,τοπία ,πορτραίτα ,αρχαιότητες ,
Reise nach der Insel Kreta im Griechischen Archipelagus im Jahre 1817.
Dedication:Content description: TitleIllustration: (Views ,varia ,)Pagination: PP25+548P+2PP, PP4+328P+28PPText Genre:ProseIllustration: (τοπία ,άλλα θέματα ,
Orthogonal cutting forces in juvenile and mature Pinus taeda wood Forças de corte ortogonal na madeira juvenil e adulta de Pinus taeda
The distinct characteristics of juvenile and mature woods, which are observed particularly in softwoods, have an influence on processing due to their different mechanical resistance properties in relation to cutting operations. In the past, when most of the wood used industrially came from adult trees of natural forests, little importance was given to a distinction between different zones of the tree stem. At present, however, as the supply of mature trees with large diameters from native forests is constantly decreasing, the use of short-cycle trees has become a common practice, through the adoption of species that grow relatively fast, such as pines and eucalyptus. In both softwoods and hardwoods, juvenile wood cells are generally smaller and thinner than in mature wood, and this reflects on their density and mechanical resistance, which should have an effect on the cutting forces developed during processing. The main object of this research was to evaluate orthogonal cutting forces in juvenile and mature Pinus taeda woods. Cutting force magnitude differences were observed for those two regions of the trunk, with parallel cutting forces being 33.4% higher, on average, at the mature wood region for 90-0 cutting, and 12% higher for 90-90 cutting. This result is consistent with the distinct anatomical structures of the material, since the forces developed during machining depend directly upon its properties.<br>As características distintas dos lenhos juvenil e adulto, existentes principalmente na formação das coníferas, influenciam na usinagem devido às diferentes propriedades de resistência mecânica ao corte. No passado, quando a maior parte da madeira utilizada industrialmente era proveniente de árvores adultas de florestas naturais, pouca importância era dada à diferenciação de zonas no tronco. Atualmente, no entanto, com o decréscimo constante do suprimento de árvores adultas de grandes diâmetros, provenientes de florestas nativas, tornou-se comum o aproveitamento da madeira de ciclos curtos, através da adoção de espécies de crescimento relativamente rápido, como exemplo os Pinus e os eucaliptos. Tanto nas coníferas quanto nas dicotiledôneas, as células da madeira juvenil são, geralmente, menores e mais delgadas do que na madeira adulta, refletindo em sua densidade e resistência, o que deverá afetar as forças de corte desenvolvidas durante o processamento. O objetivo principal desta pesquisa foi avaliar as forças de corte ortogonal nas madeiras juvenil e adulta de Pinus taeda. Houve diferenças de magnitude das forças de corte nessas duas regiões, sendo as forças de corte paralela, em média, 33,4% maiores na zona de madeira adulta, no corte 90-0, e 12% maiores no corte 90-90. Esse resultado é coerente com a diferenciação da estrutura anatômica do material, uma vez que as forças geradas durante a usinagem dependem, diretamente, de suas propriedades
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