Managed Haying and Grazing of CRP

Agricultural and Food Policy,

Essays on Moral Hazard, Bank Size, Influence, and Risk at the Federal Home Loan Banks

Two chapters of research on the Federal Home Loan Bank advances, bank risk, and influence are presented. Federal Home Loan Bank (FHLB) advances are a growing source of debt financing for US banks. FHLB advances are not priced according to bank credit risk, creating potential for moral hazard. FHLB advances are positively related to contemporary bank risk, but the relation between prior advances and subsequent risk varies between large vs. small banks depending upon the risk measure used. The relation between FHLB advances and various measures of bank risk varies between pre-crisis (2005-07), crisis (2008-09), and post-crisis (2010-12) periods differently for large vs. small banks. Thus, FHLB advances are related to bank risk, but the nature of these relations is contingent on bank size and time period. When deciding to lend advances to risky banks and thrifts, the Federal Home Loan Banks (FHLBs) weigh moral hazard incentives against charter value preservation. FHLBs may be more likely to lend to risky large members than risky community banks because large members exert significant influence over the FHLBs through their outsized capital holdings and interest payments on advances, their presence on the Board of Directors, and their ability to obtain advances from multiple FHLB districts. Between 2005 and the financial crisis pinnacle in the third quarter of 2008, the share of advances to large banks surged, even though some of those banks were on the verge of failure. A positive relationship exists among large bank advances, influence metrics, and insolvency risk, consistent with the story that FHLB moral hazard incentives outweigh charter value preservation for their largest members. Regardless of their risk and influence, banks used the advances similarly, primarily as a funding source for new loans

Source apportionment of organic gas and particulate matter pollutants using concentration and flux measurements in Delhi

One of the world’s worst cities for air pollution is Delhi, India. Past studies have shown air pollution in Delhi has a significant burden on the population’s respiratory and cardiovascular health. It is therefore important to analyse the sources of these pollutants in order to improve air quality mitigation strategies. This thesis presents time-resolved source apportionments of the organic fraction of particulate matter (PM) and of the gaseous volatile organic compounds (VOCs) that were measured in Delhi. The results of this analysis are used to identify the sources of these air pollutants and determine their atmospheric implications. Online aerosol mass spectrometry (AMS) measurements taken in Old Delhi during pre-monsoon, monsoon and post-monsoon seasons revealed concentrations of submicron particulate matter (PM1) reaching ~750 μg m-3 The largest contributing inorganic species to PM1 in the post-monsoon is nitrate (8%) but this changes to sulphate during the monsoon (24%) and premonsoon (24%). PM1 is dominated by the organics throughout the three measurement periods (54% - 68%). Source apportionment on the organics fraction using Positive Matrix Factorisation (PMF) revealed that PM1 traffic emissions are the largest contributor of primary organic aerosol (POA) in the pre-monsoon (12%) and monsoon (16%) periods. Two traffic factors were resolved: a hydrocarbon-like organic aerosol (HOA) and another HOA factor rich in nitrogen (NHOA). The N within NHOA is previously undocumented within AMS measurements and is found to be linked to nitrile species. The two traffic factors are found to have separated due to fuel-type where NHOA is related to heavy goods vehicles (HGVs) and diesel emissions while HOA is related to petrol and compressed natural gas emissions. The highest PM1 concentrations are observed in the post-monsoon period during which the highest form of POA is from a burning-related factor. These factors alone contribute 35% to the total post-monsoon increase when concentrations increase by 188%. A high correlation between one burning factor, semi-volatility biomass burning organic aerosol (SVBBOA), and Earth observation fire counts in surrounding states demonstrates its link to crop residue burning. Another burning factor, solid-fuel OA (SFOA), is found to have a high composition of polyaromatic hydrocarbons (PAHs) and novel AMS-measured marker species for polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). SFOA is therefore linked to local open-waste burning. There is also a 522% increase in chloride concentrations from pre-monsoon to post-monsoon. High correlations with SVBBOA and SFOA, suggest the post-monsoon increase in chloride is due to crop residue and open-waste burning. Future air quality mitigation strategies should concentrate on traffic emissions in order to cause a reduction PM1 across the whole year. To reduce peak PM1 concentrations during the post-monsoon, requires targeting of burning-related activities in future air quality policy. The monitoring and measurements of volatile organic compounds (VOCs) in Delhi is often overlooked. While the effects of VOCs on people’s heath is still being debated, the outcome of their interaction with the atmosphere can play a pivotal role in PM formation, OH reactivity and photochemical ozone creation potentials (POCP). For the first time, a novel approach to source apportionment was developed which allows for emission and deposition to be calculated for positive matrix factorisation (PMF) VOC source factors. Spatial flux patterns for PMF factors are presented, which give in-depth detail of the localised fluxes. A total of nine factors were resolved, of which traffic emissions are the largest (70% of total flux) and are the most significant source of OH reactivity flux and photochemical ozone creation potential (POCP). The two traffic factors separate based on the HGV restrictions causing the composition of one factor (TRAF1) to have a strong connection with diesel emissions and the other (TRAF2) with petrol and compressed natural gas. The second most significant source of emissions is an evaporative VOC (EVOC) source (10% of total flux) which has a high composition of marker species related to asphalt emissions. These are found to be naphthalene and tetralin-based structures, along with 1,3-butadiene and styrene which are constituent species of the adhesives used in asphalt. The peak in emissions of EVOC occurs during midday and follows surface temperature and solar radiation. Due to their similar meteorological controls, most of the biogenic VOCs reside within the EVOC factor. It is estimated that biogenic emissions contribute 25% to total monoterpene concentrations and 18% to the localised monoterpene fluxes. However, the traffic factors have the highest composition of monoterpenes and, as a result, they dominate the monoterpene contributions to concentrations (60%) and localised fluxes (78%). Two burning-related factors were separated, one associated with solid-fuel combustion VOCs (SFVOC) and another associated with pyrotechnical activity VOCs (PVOC). The two factors are shown to share the largest percentage of the concentration-weighted OH reactivity. This is caused by a high content of furan-based species. The first observation of a strong urban deposition flux for PMF factors is also seen for SFVOC and an oxidised VOC (OVOC1) factor. Spatial deposition flux patterns suggest vegetation could act as a VOC sink in Delhi, however, the magnitude of which could show it to be small. Over recent years, multiple PM mitigation strategies have been implemented in Delhi, but, how effective these changes have been to reduce PM is not clear. It is however possible to chart the changes in PM by analysing large archives of PM filter samples that have been collected over multiple years. An automated offline-AMS method was developed which has enabled high-throughput analysis, allowing PM concentrations to be charted over multiple years. This novel offline-AMS method uses an organic solvent mix of acetone and water which can extract high quantities of OA (95.4 ± 8.3 %). PM10 filter samples collected in Delhi for the years of 2011, 2015 and 2018, were analysed. PMF analysis was performed on the organic fraction and nine factors were resolved. These factors can be grouped into four source categories: cooking, traffic, coal-combustion and burning-related (solid fuel or open burning) OA. Burning-related OA is the highest contributor when total OA concentrations are also at their highest, during the winter and post-monsoon. As a result, burning-related OA likely contributes significantly to acute PM-related health affects in Delhi. Annual averages show a decline in burning related OA concentrations from 2015 to 2018 (47%). This could be linked to the 2015 ban on open-waste burning; however, compositional analysis of OA factors suggests municipal waste burning is still present in 2018. Further mitigation strategies are therefore required to reduce burning-related OA further. The shutdown of the two coal power stations in Delhi, along with initiatives to reduce the popularity of coal-use in businesses, residential homes, and industry, has led to a significant decrease (87%) in coal-combustion OA. Total OA concentrations were also predicted to be reduced by 17%, therefore, proving these measures brought effective reductions in PM10. The Bharat stage emissions standards for vehicles likely supressed PM10 OA concentrations as the annual averages of traffic OA factors do not reflect the coinciding rapid increase in population and registered vehicles. However, restrictions on HGVs entering during the day shows possible links to increases in PM10 concentrations during the winter and post-monsoon months. This is likely due to the large influx of diesel-engine HGVs entering the city when the boundary layer is particularly low during the early mornings and evenings

Assessing Herpetofaunal Communities and Species Monitoring in the Rolling Plains of Texas

Herpetofaunal communities have been monitored intermittently on the Matador Wildlife Management Area for the past 12 years in an attempt to understand and track species’ responses to habitat changes. This study analyzed data from all available years (2004, 2013, 2014, and 2016) with the goal of assessing habitat preference, species presence, and population trends. Herp sampling was conducted using standard Y-array drift fences with pitfall traps as well as informal road cruising and documentation of fortuitous encounters. The number of drift fences used each sampling year ranged from 10-17 and were opened for varying periods of time (9 to 61 days). A total of 23 species were trapped over all years combined, plus 11 new species documented during fortuitous encounters, compared to 43 species known from Cottle County. A species accumulation curve indicated trapping effort was insufficient to detect all species in the area. Jaccard’s dissimilarity values between trapping arrays were high, indicating little overlap in species assemblages among sites (mean dissimilarity value: 0.71). Trapping data revealed coarse habitat affinities for common species, but sample sizes limited our ability to infer specific habitat preferences or assess population trends. To meet the goal of monitoring long-term trends in herp communities and species, I recommend implementation of longer, more consistent sampling periods, a stratified sampling protocol with replication, incorporation of time-constrained searches, and improvements to the drift fence design

Compatibility studies of several molten uranium and thorium alloys in niobium, tantalum, and yttrium

Niobium, tantalum, yttrium, and Inconel have been used to contain molten aluminum, lead, tin, zinc, and several of their respective uranium and thorium alloys for various times up to 3000 hours and at temperatures ranging from 600 to 1100° C. Altogether 76 capsule tests were run, almost all in a static isothermal condition. Tantalum showed the best resistance followed by niobium, Inconel, and yttrium respectively. The systems, lead in tantalum and lead in niobium, showed the greatest potentials for possible liquid-metal fuel carrier systems. An alloy of uranium-bismuth-tin contained in tantalum also exhibited promising possibilities . The tabulated test data include a classification of the type of corrosion attack which occurred and a measured value of the amount of corrosive penetration. Each test was also given an arbitrary rating for easy reference comparisons. A number of photomicrographs are included for each set of tests

The Extreme Ultraviolet Spectrograph Sounding Rocket Payload: Recent Modifications for Planetary Observations in the EUV/FUV

We report on the status of modifications to an existing extreme ultraviolet (EUV) telescope/spectrograph sounding rocket payload for planetary observations in the 800 - 1200 A wavelength band. The instrument is composed of an existing Wolter Type 2 grazing incidence telescope, a newly built 0.4-m normal incidence Rowland Circle spectrograph, and an open-structure resistive-anode microchannel plate detector. The modified payload has successfully completed three NASA sounding rocket flights within 1994-1995. Future flights are anticipated for additional studies of planetary and cometary atmospheres and interstellar absorption. A detailed description of the payload, along with the performance characteristics of the integrated instrument are presented. In addition, some preliminary flight results from the above three missions are also presented

A review of stereochemical implications in the generation of secondary organic aerosol from isoprene oxidation

The atmospheric reactions leading to the generation of secondary organic aerosol (SOA) from the oxidation of isoprene are generally assumed to produce only racemic mixtures, but aspects of the chemical reactions suggest this may not be the case. In this review, the stereochemical outcomes of published isoprene-degradation mechanisms contributing to high amounts of SOA are evaluated. Despite evidence suggesting isoprene first-generation oxidation products do not contribute to SOA directly, this review suggests the stereochemistry of first-generation products may be important because their stereochemical configurations may be retained through to the second-generation products which form SOA. Specifically, due to the stereochemistry of epoxide ring-opening mechanisms, the outcome of the reactions involving epoxydiols of isoprene (IEPOX), methacrylic acid epoxide (MAE) and hydroxymethylmethyl-α-lactone (HMML) are, in principle, stereospecific which indicates the stereochemistry is predefined from first-generation precursors. The products from these three epoxide intermediates oligomerise to form macromolecules which are proposed to form chiral structures within the aerosol and are considered to be the largest contributors to SOA. If conditions in the atmosphere such as pH, aerosol water content, relative humidity, pre-existing aerosol, aerosol coatings and aerosol cation/anion content (and other) variables acting on the reactions leading to SOA affect the tacticity (arrangement of chiral centres) in the SOA then they may influence its physical properties, for example its hygroscopicity. Chamber studies of SOA formation from isoprene encompass particular sets of controlled conditions of these variables. It may therefore be important to consider stereochemistry when upscaling from chamber study data to predictions of SOA yields across the range of ambient atmospheric conditions. Experiments analysing the stereochemistry of the reactions under varying conditions of the above variables would help elucidate whether there is stereoselectivity in SOA formation from isoprene and if the rates of SOA formation are affected

Response of organic aerosol to Delhi's pollution control measures over the period 2011–2018

Some of the world's highest air pollution episodes occur in Delhi, India and studies have shown particulate matter (PM) is the leading air pollutant to cause adverse health effects on Delhi's population. It is therefore vital to chart sources of PM over long time periods to effectively identify trends, particularly as multiple air quality mitigation measures have been implemented in Delhi over the past 10 years but remain unevaluated. An automated offline aerosol mass spectrometry (AMS) method has been developed which has enabled high-throughput analysis of PM filters. This novel offline-AMS method uses an organic solvent mix of acetone and water to deliver high extraction recoveries of organic aerosol (OA) (95.4 ± 8.3%). Positive matrix factorisation (PMF) source apportionment was performed on the OA fraction extracted from PM10 filter samples collected in Delhi in 2011, 2015 and 2018 to provide snapshots of the responses of OA to changes in sources in Delhi. The nine factors of OA resolved by PMF group into four primary source categories: traffic, cooking, coal-combustion and burning-related (solid fuel or open burning). Burning-related OA made the largest contribution during the winter and post-monsoon, when total OA concentrations were at their highest. Annual mean burning-related OA concentrations declined by 47% between 2015 and 2018, likely associated with the 2015 ban on open waste burning and controls and incentives to reduce crop-residue burning. Compositional analysis of OA factors shows municipal waste burning tracers still present in 2018, indicating further scope to reduce burning-related OA. The closure of the two coal power stations, along with initiatives to decrease coal use in industry, businesses, and residential homes, resulted in a significant decrease (87%) in coal-combustion OA. This corresponds to a 17% reduction in total OA, which shows the effectiveness of these measures in reducing PM10. Increases in traffic OA appear to have been offset by the introduction of the Bharat stage emissions standards for vehicles as the increases do not reflect the rapid increase in registered vehicles. However, daytime restrictions on heavy goods vehicles (HGVs) entering the city is linked to large increases in PM10 during the winter and post-monsoon, likely because the large influx of diesel-engine HGVs during the early mornings and evenings is timed with a particularly low planetary boundary layer height that enhances surface concentrations