Inter-frequency Bias Estimation for the GPS Monitor Station Network

The inter-frequency bias (IFB) is present in all dual frequency combinations of GPS pseudorange and carrier phase observables. It is caused by the path dependent signal delays in both the satellite and receiver. That delay can be directly measured for a space vehicle prior to launch, or for a ground based receiver prior to its being used in the field. However the bias is known to drift, and monitoring the delay estimate by direct measurement is time consuming for ground based receivers and impossible for deployed space vehicles. Hansen (2002) examined the observability of IFB through a global model of ionosphere total electron content (TEC). Variation in the receiver portion of the IFB can also be observed in receivers with antennae in a zero-baseline configuration. This is referred to as an inter-receiver bias (IRB). In this study a Kalman filter is formulated to observe IFBs and IRBs. Process noise is used to allow the filter to track changes in the IFBs and IRBs. The filter also implements constraints to reflect the fact that a given IRB is not linearly independent of the IFBs. Because the receivers are distributed on a global scale, the Kalman filter requires a globally observable phenomenon by which to tie the IFBs. In this case ionosphere delay provides such a phenomenon. The filter was applied to observations collected by GPS monitor stations that comprise the National Geospatial- Intelligence Agency Monitor Station Network (MSN). Each monitor station contains two geodetic quality receivers in a zero-baseline configuration and continuously collects GPS observations. The GPS observations collected by this network are used to produce both precise ephemeris and the broadcast ephemeris. GPS observations made through the network are incorporated into the GPS Master Control Station (MCS) Kalman filter of the Operational Control System (OCS) (Wiley, 2006). The Kalman filter in the OCS estimates the orbital parameters that are transmitted via the navigation message. If estimated effectively, knowledge of the receiver portion of the IFB can aid in achieving better ionosphere models. IFBs are made observable using a global ionosphere delay model. A ninth order spherical harmonic model derived by Y.C. Chao (1997) was used in this study for ionosphere delay. Chao used this spherical harmonic model to capture ionospheric variations that occurred over a smaller global region in his IFB estimation process. In this study a similar model was used but was verified using observations that span a global coverage. The receiver portion of the IFB is observed precisely using the IRB. In this study error terms were introduced into the Kalman filter design to realign the IRB estimates to the IFB estimates produced for each of the two receivers in a zero baseline configuration. For a nominal epoch of measurement, there were 198 noisy measurements used each epoch to generate twelve monitor station specific IRBs. The IRB estimates showed small, decimeter level dynamic variation over the period of a day. The quality of the IFB estimate directly affects the quality of the ionospheric model formed during the estimation process. Results verify that the filter is operating properly. The ionosphere model, though simple, demonstrates that the total electron content (TEC) peaks during local noon and is at a minimum during local night. IRB estimates are roughly constant over time and have a magnitude of less than 2.5 meters. Similar estimates are formed for the IFBs, however when processing one day of observations, the IFB estimates are less stable than those of the IRBs. Future effort will involve tuning the filter, and establishing criteria for its convergence

Characterization of black walnut (Juglans nigra) cultivars for agroforestry systems

The identification of complementary species combinations will accelerate the expansion of temperate agroforestry. Since the mid-19th century, European timber plantations have taken advantage of the late-leafing habit of walnut (Juglans spp.) to grow a spring grain crop between the tree rows. A parallel but underutilized opportunity in North American involves incorporating eastern black walnut (Juglans nigra L.) cultivars into alley cropping systems. Eastern black walnut is native to North America and exhibits architectural and phenological characters for reduced competition with winter alley crops. Black walnut also produces nutritious nuts, and cultivars with improved kernel percentage and mass offer potential to cultivate the species as a domesticated orchard crop, as opposed to just the high-quality timber for which it is well-known. However, field observations suggest significant variation in tree architecture and phenology amongst cultivars, which is likely to influence complementarity with winter grains. Comprehensive characterization of trait genetic diversity is needed to best leverage germplasm into productive systems. FirstHere, we review literatureliterature is reviewed related to implementing alley cropping systems (ACS) with consideration of cultivar-dependent traits that may reduce interspecific competition. In additionIn addition, an experiment was performed characterizing black walnut cultivars for their aboveground compatibility for light inwith alley cropping systems. A population of 11 cultivars with replicates in New Franklin, MO was measured for understory light infiltration from April-June of 2021. Results showed over a two-fold difference in light infiltration between the most contrasting cultivars during the second week of May. Tree architecture and phenological event timing were also measured to determine potential causative factors of differences observed. The impact of this research may help growers interested in walnut alley cropping with cultivar selection and management practices for effective agroforestry systems. While the compatibility between tree and crops is an important factor in agroforestry design, cultivars must also be commercially productive for robust adoption by growers. An additional study was performed on the performance of 7 selections from the UMCA Black Walnut Breeding Program. A replicated population of these selections were observed in 2017 and 2021 for key traits for improving the commercial production quality of black walnut such as yield, kernel percentage and kernel mass. Results showed selections were able to significantly outperform the parental generation in these traits by as much as 135 percent. Additional years of harvest data as well as replication sites for this trial will help refine the understanding of the commercial performance of selections and allow for broader recommendations to growers at large. While the focus in this thesis is directed toward black walnut, broad characterization of other underutilized fruit/nut species will allow for robust diversification of ACS.Includes bibliographical references

The Use of Agricultural Credit Facilities by Fifty Negro Farmers Of Hopkins County, Texas

Farming as a competitive business has become acre and more dependent u^on capital to make full use of other factors of production--land, labor, and management. The wise use of capital may result in a net return that will provide progressive improvement in the farmer*s business operations and standard of living. Borrowing capital for productive purposes is a normal practice and is followed in all business enterprises, The farmer, who has the ability to use productively more capital than he owns, should borrow; and certain institutions have been developed to meet his needs. The ultimate source of funds loaned is the surplus scattered here and there over the country— a surplus which, instead of being needed and applied by the owner, is loaned at interest. The local bank, various branches of the Farm Credit administration, individual merchants, dealers, and farmer® are all managers and/or supervisors of surplus funds, which are passed on to those who are in position to use them in production. It is very important to all concerned, the owner of the surplus funds, the farmer in need of capital, and the business agency which negotiates and supervises the transfer— that the business of placing capital where it is needed, be done with maximum efficiency, and that methods be used which are most satisfactory to investors and borrowers. Financing institutions are designed to serve the needs of Agriculture and attempt to meet the requirements of the farmer1 s business. If the productivity of farmers is of such that they can pay off their mortgage within three or five years, logins should be made available for the specified time. If the farmers\u27 business is better adapted to less than annual payments of the loan, it is mo3t economical for the loan to be made in this manner. Careful consideration of the economical combination of factors of production that will render the farmers ability to repay a loan should be of primary concern of the lending agency as well as the farmer. If the purpose for which the farmer wants money is not productive and there is no substantial prospect of the ability of the borrower to make it remunerative, the loan should not be made

Automation of large scale transient protein expression in mammalian cells

Traditional mammalian expression systems rely on the time-consuming generation of stable cell lines; this is difficult to accommodate within a modern structural biology pipeline. Transient transfections are a fast, cost-effective solution, but require skilled cell culture scientists, making man-power a limiting factor in a setting where numerous samples are processed in parallel. Here we report a strategy employing a customised CompacT SelecT cell culture robot allowing the large-scale expression of multiple protein constructs in a transient format. Successful protocols have been designed for automated transient transfection of human embryonic kidney (HEK) 293T and 293S GnTI⁻ cells in various flask formats. Protein yields obtained by this method were similar to those produced manually, with the added benefit of reproducibility, regardless of user. Automation of cell maintenance and transient transfection allows the expression of high quality recombinant protein in a completely sterile environment with limited support from a cell culture scientist. The reduction in human input has the added benefit of enabling continuous cell maintenance and protein production, features of particular importance to structural biology laboratories, which typically use large quantities of pure recombinant proteins, and often require rapid characterisation of a series of modified constructs. This automated method for large scale transient transfection is now offered as a Europe-wide service via the P-cube initiative

High Redshift AGN: Accretion Rates and Morphologies for X-ray and Radio SC4K Sources from z~2 to z~6

We study a large sample of ~4000 Lyα Emitters (LAEs) and identify the active galactic nuclei (AGN) among them in order to characterise their evolution across cosmic time. This work was carried out using the SC4K survey (Sobral et al. 2018) and data collected by the Hubble Space Telescope (HST), Chandra X-ray Observatory and the Very Large Array (VLA). We find 322 X-ray or radio detected AGN within the sample, constituting 8.7±0.5% of the sources considered. We find that the vast majority of classifiable AGN (81±3%) are point-like or compact sources in the rest-frame UV seen with HST, and this qualitative trend holds regardless of detection band or redshift. These AGN have a range of black hole accretion rates (BHARs), and we present the first direct comparison between radio and X-ray BHARs. X-ray calculated BHARs range from ~0.07 M⊙/yr to ~23 M⊙/yr, indicating a highly varied sample, with some very active AGN detected. Radio calculated BHARs range from ~0.09 M⊙/yr to ~8.8 M⊙/yr, broadly tracing the same range as the X-ray calculated BHARs. X-ray calculated BHARs peak at z~3 and both radio and X-ray calculated BHARs increase with increasing redshift, plateauing at z~4. We find significantly less variation in radio BHARs when compared to X-ray BHARs, indicating radio may be a far more stable and reliable method of calculating the BHARs of AGN over large timescales, while X-ray is more suitable for instantaneous BHARs

Comparing Tree‐Ring and Permanent Plot Estimates of Aboveground Net Primary Production in Three Eastern U.S. Forests

Forests account for a large portion of sequestered carbon, much of which is stored as wood in trees. The rate of carbon accumulation in aboveground plant material, or aboveground net primary productivity (aNPP), quantifies annual to decadal variations in forest carbon sequestration. Permanent plots are often used to estimate aNPP but are usually not annually resolved and take many years to develop a long data set. Tree rings are a unique and infrequently used source for measuring aNPP, and benefit from fine spatial (individual trees) and temporal (annual) resolution. Because of this precision, tree rings are complementary to permanent plots and the suite of tools used to study forest productivity. Here we evaluate whether annual estimates of aNPP developed from tree rings approximate estimates derived from colocated permanent plots. We studied a lowland evergreen (Howland, Maine), mixed deciduous (Harvard Forest, Massachusetts), and mixed mesophytic (Fernow, West Virginia) forest in the eastern United States. Permanent plots at the sites cover an area of 2–3 ha, and we use these areas as benchmarks indicative of the forest stand. We simulate random draws of permanent plot subsets to describe the distribution of aNPP estimates given a sampling area size equivalent to the tree-ring plots. Though mean tree-ring aNPP underestimates permanent plot aNPP slightly at Howland and Fernow and overestimates at Harvard Forest when compared with the entire permanent plot, it is within the 95% confidence interval of the random draws of equal-sized sampling area at all sites. To investigate whether tree-ring aNPP can be upscaled to the stand, we conducted a second random draw of permanent plot subsets simulating a twofold increase in sampling area. aNPP estimates from this distribution were not significantly different from results of the initial sampling area, though variance decreased as sampling area approaches stand area. Despite several concerns to consider when using tree rings to reconstruct aNPP (e.g., upscaling, allometric, and sampling uncertainties), the benefits are apparent, and we call for the continued application of tree rings in carbon cycle studies across a broader range of species diversity, productivity, and disturbance histories to fully develop this potential

Comparing Tree-Ring And Permanent Plot Estimates Of Aboveground Net Primary Production In Three Eastern U.S. Forests

Forests account for a large portion of sequestered carbon, much of which is stored as wood in trees. The rate of carbon accumulation in aboveground plant material, or aboveground net primary productivity (aNPP), quantifies annual to decadal variations in forest carbon sequestration. Permanent plots are often used to estimate aNPP but are usually not annually resolved and take many years to develop a long data set. Tree rings are a unique and infrequently used source for measuring aNPP, and benefit from fine spatial (individual trees) and temporal (annual) resolution. Because of this precision, tree rings are complementary to permanent plots and the suite of tools used to study forest productivity. Here we evaluate whether annual estimates of aNPP developed from tree rings approximate estimates derived from colocated permanent plots. We studied a lowland evergreen (Howland, Maine), mixed deciduous (Harvard Forest, Massachusetts), and mixed mesophytic (Fernow, West Virginia) forest in the eastern United States. Permanent plots at the sites cover an area of 2-3 ha, and we use these areas as benchmarks indicative of the forest stand. We simulate random draws of permanent plot subsets to describe the distribution of aNPP estimates given a sampling area size equivalent to the tree-ring plots. Though mean tree-ring aNPP underestimates permanent plot aNPP slightly at Howland and Fernow and overestimates at Harvard Forest when compared with the entire permanent plot, it is within the 95% confidence interval of the random draws of equal-sized sampling area at all sites. To investigate whether tree-ring aNPP can be upscaled to the stand, we conducted a second random draw of permanent plot subsets simulating a twofold increase in sampling area. aNPP estimates from this distribution were not significantly different from results of the initial sampling area, though variance decreased as sampling area approaches stand area. Despite several concerns to consider when using tree rings to reconstruct aNPP (e.g., upscaling, allometric, and sampling uncertainties), the benefits are apparent, and we call for the continued application of tree rings in carbon cycle studies across a broader range of species diversity, productivity, and disturbance histories to fully develop this potential

Darling Nelly Gray

1. There\u27s low green valley on the low Kentucky shore, There I\u27ve whiled many happy hours away, A sitting and a singing by the little cottage door Where lived my darling Nelly Gray. CHORUS: Oh! my poor Nelly Gray, they have taken you away And I\u27ll never see my darling any more, I\u27m sitting by the river and I\u27m weeping all the day, For you\u27ve gone from the old Kentucky shore. 2. When the moon had climb\u27d the mountain and the stars were shining too, Then I\u27d take my darling Nelly Gray, And we\u27d float down the river in my little red canoe, While my banjo sweetly I would play. 3. I went to see her but she\u27s gone! the neighbors say, The white man bound her with his chain, They have taken her to Georgia for to wear her life away, As she toils in the cotton and the cane. 4. My canoe is underwater and my banjo is unstrung, I\u27m tired of living any more, My eyes shall look downward and my songs shall be unsung While I stay on the old Kentucky shore. 5. My eyes are getting blinded and I cannot see my way, Hark! there\u27s somebody knocking at the door Oh! I hear the angels calling and I see my Nelly Gray Farewell to the old Kentucky shore. CHORUS: Oh! my darling Nelly Gray, up in heaven there they say, That they\u27ll never take you from me any more, I\u27m a coming coming coming, as the angels clear the way, Farewell to the old Kentucky shore