82 research outputs found

    A memorandum on trade with Soviet Russia: submitted to the Committee on Foreign Relations of the United States Senate, January, 1921...

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    https://stars.library.ucf.edu/prism/1760/thumbnail.jp

    Studies of the MLT/I using Multistatic Meteor Radar

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    This thesis applies a multistatic meteor radar to an investigation of the dynamics of the mesosphere lower thermosphere/ionosphere (MLT/I; 60-110 km altitude). The main radar used in the study operates at 55 MHz and is in the vicinity of Adelaide, South Australia, consisting of a monostatic radar at the Buckland Park eld site (34.6 S, 138.5 E) and a bistatic receiver located about 55 km south-east at a site in the Adelaide Hills (35.1 S, 138.8 E). The areas of investigation pertaining to MLT/I dynamics include assessing the ability of a multistatic meteor radar to measure the vertical ux of horizontal momentum and studying the interaction between gravity waves and tidal e ects. The thesis also presents a novel phase calibration technique for meteor radars, based on the use of civilian aircraft. The assessment of this radar's ability to measure MLT/I momentum uxes demonstrated that a relative uncertainty of about 75% can be expected for a monostatic con guration, assuming a ux magnitude of 20 m2s-2, a single day of integration, and a gravity wave field synthesized from a realistic spectral model. The multistatic configuration with a single bistatic receiver is shown to yield a relative uncertainty of about 65% under the same conditions. It is suggested that the increase in precision can be attributed entirely to the increase in the number of meteor detections associated with the combined monostatic and bistatic receivers, rather than due to the existence of a more favourable distribution of Bragg vectors arising from the receiver separation. A case study of winds around the autumnal equinox of 2018 revealed large modulations in diurnal tidal amplitudes, with peak component diurnal tide amplitudes of 50 ms-1 and peak zonal wind velocities of 140 ms-1. In the context of the need to verify the accuracy of momentum ux estimates from the radar, this motivated an investigation into the role momentum transport from gravity wave breaking played in modulating the tidal amplitudes. The investigation showed that while the observed gravity wave forcing exhibited a complex relationship with the tidal winds, the components of the forcing were generally seen to be approximately out of phase with the tidal winds above altitudes of 88 km. Additionally, no clear phase relationship between the tides and gravity wave forcing was observed below 88 km. Following the case study, the altitude and angle-of-arrival (AOA) errors and reduced meteor detection rates associated with suspected receiver phase calibration errors motivated the development of an alternative phase calibration technique. The technique developed was based on the use of echoes from civilian aircraft with known positions. Approximately two weeks worth of aircraft detections with the radar and a 1090 MHz Automatic Dependent Surveillance Broadcast receiver (used to receive aircraft position information) was acquired during November 2019. By taking into account the implied phase correction variability with AOA using a beamforming approach, it was shown that the aircraft-based corrections yielded an equal or smaller meteor height distribution width than the conventionally used empirical phase calibration technique. Assuming that a smaller height distribution width equates to smaller average height estimation errors, this was taken to mean that the aircraft-based approach outperformed the empirical one.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 202

    Strengths and Limitations of Nitrogen Rate Recommendations for Corn and Opportunities for Improvement

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    Nitrogen fixation by the Haber–Bosch process has more than doubled the amount of fixed N on Earth, significantly influencing the global N cycle. Much of this fixed N is made into N fertilizer that is used to produce nearly half of the world’s food. Too much of the N fertilizer pollutes air and water when it is lost from agroecosystems through volatilization, denitrification, leaching, and runoff. Most of the N fertilizer used in the United States is applied to corn (Zea mays L.), and the profitability and environmental footprint of corn production is directly tied to N fertilizer applications. Accurately predicting the amount of N needed by corn, however, has proven to be challenging because of the effects of rainfall, temperature, and interactions with soil properties on the N cycle. For this reason, improving N recommendations is critical for profitable corn production and for reducing N losses to the environment. The objectives of this paper were to review current methods for estimating N needs of corn by: (i) reviewing fundamental background information about how N recommendations are created; (ii) evaluating the performance, strengths, and limitations of systems and tools used for making N fertilizer recommendations; (iii) discussing how adaptive management principles and methods can improve recommendations; and (iv) providing a framework for improving N fertilizer rate recommendations

    Momentum Flux Spectra of a Mountain Wave Event Over New Zealand

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    During the Deep Propagating Gravity Wave Experiment (DEEPWAVE) 13 July 2014 research flight over the South Island of New Zealand, a multiscale spectrum of mountain waves (MWs) was observed. High-resolution measurements of sodium densities were available from ~70 to 100 km for the duration of this flight. A comprehensive technique is presented for obtaining temperature perturbations, Tâ€Č, from sodium mixing ratios over a range of altitudes, and these Tâ€Č were used to calculate the momentum flux (MF) spectra with respect to horizontal wavelengths, λH, for each flight segment. Spectral analysis revealed MWs with spectral power centered at λH of ~80, 120, and 220 km. The temperature amplitudes of these MWs varied between the four cross-mountain flight legs occurring between 6:10UT and 9:10UT. The average spectral Tâ€Č amplitudes near 80 km in altitude ranged from 7–13 K for the 220 km λH MW and 4–8 K for the smaller λH MWs. These amplitudes decayed significantly up to 90 km, where a critical level for MWs was present. The average MF per unit mass near 80 km in altitude ranged from ~13 to 60 m2/s2 across the varying spectra over the duration of the research flight and decayed to ~0 by 88 km in altitude. These MFs are large compared to zonal means and highlight the importance of MWs in the momentum budget of the mesosphere and lower thermosphere at times when they reach these altitudes

    Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

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    Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment’s change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of inter annual variation in potential ET divided by P (PET/P; dryness index) to inter annual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., non-resilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to climate warming than the more diverse mixed forest catchments

    A polymorphic transcriptional regulatory domain in the amyotrophic lateral sclerosis risk gene <i>CFAP410</i> correlates with differential isoform expression.

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    We describe the characterisation of a variable number tandem repeat (VNTR) domain within intron 1 of the amyotrophic lateral sclerosis (ALS) risk gene CFAP410 (Cilia and flagella associated protein 410) (previously known as C21orf2), providing insight into how this domain could support differential gene expression and thus be a modulator of ALS progression or risk. We demonstrated the VNTR was functional in a reporter gene assay in the HEK293 cell line, exhibiting both the properties of an activator domain and a transcriptional start site, and that the differential expression was directed by distinct repeat number in the VNTR. These properties embedded in the VNTR demonstrated the potential for this VNTR to modulate CFAP410 expression. We extrapolated these findings in silico by utilisation of tagging SNPs for the two most common VNTR alleles to establish a correlation with endogenous gene expression. Consistent with in vitro data, CFAP410 isoform expression was found to be variable in the brain. Furthermore, although the number of matched controls was low, there was evidence for one specific isoform being correlated with lower expression in those with ALS. To address if the genotype of the VNTR was associated with ALS risk, we characterised the variation of the CFAP410 VNTR in ALS cases and matched controls by PCR analysis of the VNTR length, defining eight alleles of the VNTR. No significant difference was observed between cases and controls, we noted, however, the cohort was unlikely to contain sufficient power to enable any firm conclusion to be drawn from this analysis. This data demonstrated that the VNTR domain has the potential to modulate CFAP410 expression as a regulatory element that could play a role in its tissue-specific and stimulus-inducible regulation that could impact the mechanism by which CFAP410 is involved in ALS

    The Care Home Independent Pharmacist Prescriber Study (CHIPPS) : Development and implementation of an RCT to estimate safety, effectiveness and cost-effectiveness

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    This research was supported by the National Institute for Health and Care Research (NIHR) Yorkshire and Humber Patient Safety Translational Research Centre (NIHR YH PSTRC). The views expressed in this article are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. This report is dedicated to Kate Massey, an active and enthusiastic member of the CHIPPS patient and public involvement team who sadly passed away during the delivery of this study.Peer reviewedPublisher PD

    Wave-current interaction in Willapa Bay

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    Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): C12014, doi:10.1029/2011JC007387.This paper describes the importance of wave-current interaction in an inlet-estuary system. The three-dimensional, fully coupled, Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system was applied in Willapa Bay (Washington State) from 22 to 29 October 1998 that included a large storm event. To represent the interaction between waves and currents, the vortex-force method was used. Model results were compared with water elevations, currents, and wave measurements obtained by the U.S. Army Corp of Engineers. In general, a good agreement between field data and computed results was achieved, although some discrepancies were also observed in regard to wave peak directions in the most upstream station. Several numerical experiments that considered different forcing terms were run in order to identify the effects of each wind, tide, and wave-current interaction process. Comparison of the horizontal momentum balances results identified that wave-breaking-induced acceleration is one of the leading terms in the inlet area. The enhancement of the apparent bed roughness caused by waves also affected the values and distribution of the bottom shear stress. The pressure gradient showed significant changes with respect to the pure tidal case. During storm conditions the momentum balance in the inlet shares the characteristics of tidal-dominated and wave-dominated surf zone environments. The changes in the momentum balance caused by waves were manifested both in water level and current variations. The most relevant effect on hydrodynamics was a wave-induced setup in the inner part of the estuary.Primary funding for this study was furnished by the U.S. Geological Survey, Coastal and Marine Geology Program, under the Carolinas Coastal Change Processes Project.2012-06-1
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