435 research outputs found
Project Echo: System Calculations
The primary experimental objective of Project Echo was the transmission of radio communications between points on the earth by reflection from the balloon satellite. This paper describes system calculations made in preparation for the experiment and their adaptation to the problem of interpreting the results. The calculations include path loss computations, expected audio signal-to-noise ratios, and received signal strength based on orbital parameters
Rock magnetic and geochemical evidence for authigenic magnetite formation via iron reduction in coal-bearing sediments offshore Shimokita Peninsula, Japan (IODP Site C0020)
Sediments recovered at Integrated Ocean Drilling Program (IODP) Site C0020, in a foreâarc basin offshore Shimokita Peninsula, Japan, include numerous coal beds (0.3â7 m thick) that are associated with a transition from a terrestrial to marine depositional environment. Within the primary coalâbearing unit (âŒ2 km depth below seafloor) there are sharp increases in magnetic susceptibility in close proximity to the coal beds, superimposed on a background of consistently low magnetic susceptibility throughout the remainder of the recovered stratigraphic sequence. We investigate the source of the magnetic susceptibility variability and characterize the dominant magnetic assemblage throughout the entire cored record, using isothermal remanent magnetization (IRM), thermal demagnetization, anhysteretic remanent magnetization (ARM), iron speciation, and iron isotopes. Magnetic mineral assemblages in all samples are dominated by very lowâcoercivity minerals with unblocking temperatures between 350 and 580°C that are interpreted to be magnetite. Samples with lower unblocking temperatures (300â400°C), higher ARM, higherâfrequency dependence, and isotopically heavy ÎŽ56Fe across a range of lithologies in the coalâbearing unit (between 1925 and 1995 mbsf) indicate the presence of fineâgrained authigenic magnetite. We suggest that ironâreducing bacteria facilitated the production of fineâgrained magnetite within the coalâbearing unit during burial and interaction with pore waters. The coal/peat acted as a source of electron donors during burial, mediated by humic acids, to supply ironâreducing bacteria in the surrounding siliciclastic sediments. These results indicate that coalâbearing sediments may play an important role in iron cycling in subsiding peat environments and if buried deeply through time, within the subsequent deep biosphere
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Seed yield and yield components of Pennfine perennial ryegrass (Lolium perenne L.) as influenced by time and rate of spring nitrogen and chemical dwarfing
Seed yield in perennial ryegrass is the product of yield components
that develop during the life of the plant. Crop yield potential is
defined by the number of fertile tillers, spikelets per spike, and
florets per spikelet. It has been shown that perennial ryegrass
realizes only a small percentage of the potential as harvested seed, and
is an inherently poor seed producer as cultivars have been selected
primarily for vegetative production or desirable turf characteristics.
The Willamette Valley of Oregon produces nearly all of the
perennial ryegrass seed grown in the United States. Environmental
conditions during plant growth control potential yield development and
the efficiency with which it is used. To increase the efficiency of
seed production, it is important to understand the effects specialized
cultural management techniques have in this producing region.
In these studies on perennial ryegrass, the effects of varying the
amount and time of spring applied nitrogen (N), and the effects of the
plant growth retardant paclobutrazol were investigated under field
conditions using the cultivar Pennfine. In addition, the influence of
high levels of early spring N, combined with growth retardant use was
investigated.
Increased tiller densities, the result of higher N level, can
result in a greater seed yield potential. However, as tiller densities
become greater, the components of seed yield on individual tillers
become smaller. In addition, earlier and more severe lodging result in
greater tiller mortality and harvest dry weight losses. Split spring
applications totaling 120 to 150 kg N haâ»Âč appeared to provide a better
balance between compensating yield components, while maintaining an
economic seed yield.
Spring application of paclobutrazol delayed the onset and severity
of lodging, resulting in an increased number of fertile tillers in the
stand, and a greater number of potential seed sites per unit area.
Earlier dates of application had a greater effect in reducing lodging in
1983, but no difference was observed between two spring growth stages in
1984. Reduced lodging appears to enhance seed set, resulting in a
greater number of seeds recovered at harvest and a higher floret site
utilization (FSU). Harvest index was also increased with paclobutrazol.
Application of paclobutrazol significantly increased seed yield, a
result of improved seed recovery due to more seeds per spike. However,
the increased yield potential resulting from higher N rate was not
recovered by application of paclobutrazol where severe lodging
conditions occurred prior to the completion of seed filling. Under more
normal environmental conditions, 120 kg N haâ»Âč, followed with a growth
retardant application, had a significantly greater seed yield than the
other treatments
Isolating detrital and diagenetic signals in magnetic susceptibility records from methane-bearing marine sediments
© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Johnson, J. E., Phillips, S. C., Clyde, W. C., Giosan, L., & Torres, M. E. Isolating detrital and diagenetic signals in magnetic susceptibility records from methane-bearing marine sediments. Geochemistry Geophysics Geosystems, 22(9), (2021): e2021GC009867, https://doi.org/10.1029/2021GC009867.Volume-dependent magnetic susceptibility (Îș) is commonly used for paleoenvironmental reconstructions in both terrestrial and marine sedimentary environments where it reflects a mixed signal between primary deposition and secondary diagenesis. In the marine environment, Îș is strongly influenced by the abundance of ferrimagnetic minerals regulated by sediment transport processes. Post-depositional alteration by H2S, however, can dissolve titanomagnetite, releasing reactive Fe that promotes pyritization and subsequently decreases Îș. Here, we provide a new approach for isolating the detrital signal in Îș and identifying intervals of diagenetic alteration of Îș driven by organoclastic sulfate reduction (OSR) and the anaerobic oxidation of methane (AOM) in methane-bearing marine sediments offshore India. Using the correlation of a heavy mineral proxy from X-ray fluorescence data (Zr/Rb) and Îș in unaltered sediments, we predict the primary detrital Îș signal and identify intervals of decreased Îș, which correspond to increased total sulfur content. Our approach is a rapid, high-resolution method that can identify overprinted Îș resulting from pyritization of titanomagnetite due to H2S production in marine sediments. In addition, total organic carbon, total sulfur, and authigenic carbonate ÎŽ13C measurements indicate that both OSR and AOM can drive the observed Îș loss, but AOM drives the greatest decreases in Îș. Overall, our approach can enhance paleoenvironmental reconstructions and provide insight into paleo-positions of the sulfate-methane transition zone, past enhancements of OSR or paleo-methane seepage, and the role of detrital iron oxide minerals on the marine sediment sulfur sink, with consequences influencing the development of chemosynthetic biological communities at methane seeps.This research was supported by the American Chemical Society-Petroleum Research Fund Award #53006-ND8 and U.S. Department of Energy Grant #DE-FE0010120
Isolating Detrital and Diagenetic Signals in Magnetic Susceptibility Records From Methane-Bearing Marine Sediments
Volume-dependent magnetic susceptibility (Îș) is commonly used for paleoenvironmental reconstructions in both terrestrial and marine sedimentary environments where it reflects a mixed signal between primary deposition and secondary diagenesis. In the marine environment, Îș is strongly influenced by the abundance of ferrimagnetic minerals regulated by sediment transport processes. Post-depositional alteration by H2S, however, can dissolve titanomagnetite, releasing reactive Fe that promotes pyritization and subsequently decreases Îș. Here, we provide a new approach for isolating the detrital signal in Îș and identifying intervals of diagenetic alteration of Îș driven by organoclastic sulfate reduction (OSR) and the anaerobic oxidation of methane (AOM) in methane-bearing marine sediments offshore India. Using the correlation of a heavy mineral proxy from X-ray fluorescence data (Zr/Rb) and Îș in unaltered sediments, we predict the primary detrital Îș signal and identify intervals of decreased Îș, which correspond to increased total sulfur content. Our approach is a rapid, high-resolution method that can identify overprinted Îș resulting from pyritization of titanomagnetite due to H2S production in marine sediments. In addition, total organic carbon, total sulfur, and authigenic carbonate ÎŽ13C measurements indicate that both OSR and AOM can drive the observed Îș loss, but AOM drives the greatest decreases in Îș. Overall, our approach can enhance paleoenvironmental reconstructions and provide insight into paleo-positions of the sulfate-methane transition zone, past enhancements of OSR or paleo-methane seepage, and the role of detrital iron oxide minerals on the marine sediment sulfur sink, with consequences influencing the development of chemosynthetic biological communities at methane seeps
Ozonation process analysis. Project 2697-3, report three : a progress report to the Fourdrinier Kraft Board Group of the American Paper Institute
"August 29, 1980.""The Institute of Paper Chemistry, William C. Krueger ... William J. Whitsitt ... Clyde H. Sprague.
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Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA
Paleogene hyperthermals, including the PaleoceneâEocene Thermal Maximum (PETM) and several other smaller events, represent global perturbations to Earthâs climate system and are characterized by warmer temperatures, changes in floral and faunal communities, and hydrologic changes. These events are identified in the geologic record globally by negative carbon isotope excursions (CIEs), resulting from the input of isotopically light carbon into Earthâs atmosphere. Much about the causes and effects of hyperthermals remains uncertain, including whether all hyperthermals were caused by the same underlying processes, how biotic effects scale with the magnitude of hyperthermals, and why CIEs are larger in paleosol carbonates relative to marine records. Resolving these questions is crucial for a full understanding of the causes of hyperthermals and their application to future climate scenarios. The primary purpose of this study was to identify early Eocene hyperthermals in the Fifteenmile Creek area of the south-central Bighorn Basin, Wyoming, USA. This area preserves a sequence of fluvial floodplain sedimentary rocks containing paleosol carbonates and an extensive record of fossil mammals. Previous analysis of faunal assemblages in this area revealed two pulses of mammal turnover and changes in diversity interpreted to correlate with the ETM2 and H2 hyperthermals that follow the PETM. This was, however, based on long-distance correlation of the fossil record in this area with chemostratigraphic records from elsewhere in the basin.
We present new carbon isotope stratigraphies using micrite ÎŽ13C values from paleosol carbonate nodules preserved in and between richly fossiliferous mammal localities at Fifteenmile Creek to identify the stratigraphic positions of ETM2 and H2. Carbon isotope results show that the ETM2 and H2 hyperthermals, and possibly the subsequent I1 hyperthermal, are recorded at Fifteenmile Creek. ETM2 and H2 overlap with the two previously recognized pulses of mammal turnover. The CIEs for these hyperthermals are also somewhat smaller in magnitude than in more northerly Bighorn Basin records. We suggest that basin-wide differences in soil moisture and/or vegetation could contribute to variable CIE amplitudes in this and other terrestrial records
New Archaeocetes (Mammalia, Cetacea) from the Middle Eocene Domanda Formation of Sulaiman Range, Punjab (Pakistan)
291-330http://deepblue.lib.umich.edu/bitstream/2027.42/48650/2/ID517.pd
Note and Comment
The Basis of Relief from Penalties and Forfeitures - The equitable principle of relief from penalties and forfeitures is so far elementary as almost to defy analysis. Many, perhaps most, of the judicial explanations of the principle have based it upon interpretation or construction, appealing to the doctrine that equity regards intent rather than form. Yet a logical application of this doctrine would lead to results very different from those which have actually been arrived at in the decisions. Thus, a stipulation in a mortgage that the mortgagor waives his equity of redemption can hardly be interpreted as meaning that he does not waive it, yet all such stipulations are ignored and redemption granted, nevertheless. Again, a penalty for breach of contract cannot be saved by the most solemn declaration that it is intended as liquidated damages. It must be conceded that many cases have actually been, decided on the interpretation theory, producing such enormities as Iowa Land Co. v. Mickel, 41 Ia. 4o2 (sale of land, 6oo paid, 150 one day late due to a misunderstanding; held forfeited), and Doctornan v. Schroeder, 114 AUt. 8io (N. J., 1921; sale of land, iooo thirty minutes late; held forfeited). But such cases represent the minority view, and one applicable only to instalment sales, no court pursuing this course in mortgage or liquidated damage cases
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