Management effects on the environmental footprint of swine production

Livestock production in general is a very small contributor to GHG emissions. However, swine producers will continually be faced with a series of challenges to minimize the environmental impact of swine production. The main objectives of the the studies in this thesis were to evaluate the effects of reducing dietary CP with the supplementation of synthetic AA and the effects of feeding diets with or without antibiotics on manure generation and excretion of N and C. In Exp. 1, thirty-two barrows were used in a metabolism study to evaluate the effect of feeding reduced CP, amino acid (AA) supplemented diets on nutrient excretion. Pigs were assigned to one of four dietary treatments: 1) Control: Corn-SBM-DDGS diets with no synthetic AA, 2) 1X reduction in CP, 3) 2X reduction in CP, and 4) 3X reduction in CP. Diet 4 was balanced on the 7th limiting AA, phenylalanine. Diets 2 and 3 were then formulated to have a stepwise reduction in CP between Diets 1 and 4. Diets 2-4 were supplemented with synthetic amino acids as needed to meet amino acid needs based on NRC 2012 AA minimum ratios for the 7 age phases tested. Low-CP AA supplemented diets significantly reduce N excretion by up to 45%. In addition, VFA concentrations were reduced between 9-17% when dietary CP content was reduced up to 3X levels. Overall fecal C excreted (g/pig/d) was greatest for the lowest CP (3X), largely due to the % C digested being the lowest for that diet. Both DE and ME, were linearly (P \u3c 0.0001) decreased by approximately 6 and 5% respectively with increasing reductions in dietary CP. In Exp. 2, seven hundred twenty-three pigs were placed into eleven identical, environmentally controlled rooms for a wean-to-finish study. Pigs were allotted to one of two dietary treatments: 1) Control: Corn-SBM-DDGS diets with Antibiotics, and 2) Antibiotic Free; treatment 1 less the antibiotics but with alternative supplements. Diets were fed in nine dietary phases. There was a tendency for greater final BW and BW gain per manure pit when pigs were fed the control antibiotic treatment. No significant differences were observed between the two dietary treatments for manure volume (L), manure volume per kg BW gain, DM (g/kg BW gain), N (g/kg BW gain), and AmmN (g/kg BW gain). Manure pH tended to be lower for pigs fed the antibiotic free diet (P \u3c 0.06) compared to the control diet. There were no differences observed for manure total C (kg), manure C per kg BW gain, manure C g/pig/d, and manure C g/pig wean-to-finish. In summary, Exp. 1 low CP diets with synthetic AA supplementation result in lower DE and ME values and C digestibility for the lowest CP diets, but significantly reduce N and VFA excretions. In Exp. 2, the antibiotic free diets had similar manure nutrient excretion and generation with lower manure pH which may affect transformation of N2O during manure land application. The adoption of technologies like these evaluated in this thesis will be of the utmost importance in remaining proactive in finding a way to meet the demands of a growing world population in a manner that is cost effective for the producer, while being environmentally sustainable

Fundamental Limitations of Cavity-assisted Atom Interferometry

Atom interferometers employing optical cavities to enhance the beam splitter pulses promise significant advances in science and technology, notably for future gravitational wave detectors. Long cavities, on the scale of hundreds of meters, have been proposed in experiments aiming to observe gravitational waves with frequencies below 1 Hz, where laser interferometers, such as LIGO, have poor sensitivity. Alternatively, short cavities have also been proposed for enhancing the sensitivity of more portable atom interferometers. We explore the fundamental limitations of two-mirror cavities for atomic beam splitting, and establish upper bounds on the temperature of the atomic ensemble as a function of cavity length and three design parameters: the cavity g-factor, the bandwidth, and the optical suppression factor of the first and second order spatial modes. A lower bound to the cavity bandwidth is found which avoids elongation of the interaction time and maximizes power enhancement. An upper limit to cavity length is found for symmetric two-mirror cavities, restricting the practicality of long baseline detectors. For shorter cavities, an upper limit on the beam size was derived from the geometrical stability of the cavity. These findings aim to aid the design of current and future cavity-assisted atom interferometers.Comment: 11 pages, 12 figure

Electrical Control of Two-Dimensional Neutral and Charged Excitons in a Monolayer Semiconductor

Monolayer group VI transition metal dichalcogenides have recently emerged as semiconducting alternatives to graphene in which the true two-dimensionality (2D) is expected to illuminate new semiconducting physics. Here we investigate excitons and trions (their singly charged counterparts) which have thus far been challenging to generate and control in the ultimate 2D limit. Utilizing high quality monolayer molybdenum diselenide (MoSe2), we report the unambiguous observation and electrostatic tunability of charging effects in positively charged (X+), neutral (Xo), and negatively charged (X-) excitons in field effect transistors via photoluminescence. The trion charging energy is large (30 meV), enhanced by strong confinement and heavy effective masses, while the linewidth is narrow (5 meV) at temperatures below 55 K. This is greater spectral contrast than in any known quasi-2D system. We also find the charging energies for X+ and X- to be nearly identical implying the same effective mass for electrons and holes.Comment: 11 pages main text with 4 figures + 7 pages supplemental material

Mapping regional cooperation of state actors for health research systems in Africa:: a social network analysis

Regional bodies can potentially play an important role in improving health research in Africa. This study analyses the network of African state-based regional organisations for health research and assesses their potential relationship with national health research performance metrics. After cataloguing organisations and their membership, we conducted a social network analysis to determine key network attributes of national governments’ connections via regional organisations supporting functions of health research systems. This data was used to test the hypothesis that state actors with more connections to other actors via regional organisations would have higher levels of health research performance across indicators. With 21 unique regional organisations, the African continent is densely networked around health research systems issues. In general, the regional network for health research is inclusive. No single actor serves as a nexus. However, when statistics are grouped by African Union regions, influential poles emerge, with the most predominate spheres of influence in East and West Africa. Further, when connectivity data was analysed against national health research performance, there were no statistically significant relationships between increased connectivity and higher performance of key health research metrics. The inclusive and dense network dynamics of African regional organisations for health research strengthening present key opportunities for knowledge diffusion and cooperation to improve research capacity on the continent. Further reflection is needed on appropriate and meaningful ways to assess the role of regionalism and evaluate the influence of regional organisations in strengthening health research systems in Africa

Patient-Reported Outcomes in Middle Ear and Active Transcutaneous Bone Conduction Hearing Implants

OBJECTIVE: This study used questionnaires to examine the patient-reported satisfaction with 2 hearing implant devices to determine the level of overall satisfaction with the devices, which, if any, factors predicted good or poor perceived outcomes, or whether there were any specific aspects of the devices where dissatisfaction was apparent. METHODS: A post-treatment questionnaire survey of 39 adult patients who had received a Vibrant Soundbridge (VSB) or Bonebridge (BB) hearing implant, with at least 3 months of follow-up, was conducted using the Glasgow Benefit Inventory (GBI) and Hearing Device Satisfaction Scale (HDSS). Satisfaction scores were compared to pre- and post-operative audiologic outcomes. The correlation between GBI and HDSS scores was also examined. RESULTS: A total of 28 of the 39 patients (72%) responded: 13 with a BB and 15 with a VSB at a mean of 13 months after implantation. The overall mean total GBI score was 30, with no significant differences across the groups. The responders generally reported that they were “satisfied” across most domains of the HDSS. In the study, 25 of the 28 responders were largely satisfied with their devices but 3 respondents were not. Two were known non-users, while one used the device but did not gain the benefit expected. It is instructive to note that all of these dissatisfied recipients were close to the manufacturer recommended limits for implantation of their respective devices at the time of surgery

Population pulsation resonances of excitons in monolayer MoSe2 with sub 1 {\mu}eV linewidth

Monolayer transition metal dichalcogenides, a new class of atomically thin semiconductors, possess optically coupled 2D valley excitons. The nature of exciton relaxation in these systems is currently poorly understood. Here, we investigate exciton relaxation in monolayer MoSe2 using polarization-resolved coherent nonlinear optical spectroscopy with high spectral resolution. We report strikingly narrow population pulsation resonances with two different characteristic linewidths of 1 {\mu}eV and <0.2 {\mu}eV at low-temperature. These linewidths are more than three orders of magnitude narrower than the photoluminescence and absorption linewidth, and indicate that a component of the exciton relaxation dynamics occurs on timescales longer than 1 ns. The ultra-narrow resonance (<0.2 {\mu}eV) emerges with increasing excitation intensity, and implies the existence of a long-lived state whose lifetime exceeds 6 ns.Comment: (PRL, in press

Photoperiod Manipulation Reveals a Light-Driven Component to Daily Patterns of Ventilation in Male C57Bl/6J Mice

Obstructive sleep apnea is a common sleep disorder that increases risk for cardiovascular disease and mortality. The severity of sleep-disordered breathing in obstructive sleep apnea patients fluctuates with the seasons, opening the possibility that seasonal changes in light duration, or photoperiod, can influence mechanisms of breathing. Photoperiod can have profound effects on internal timekeeping and can reshape metabolic rhythms in mammals. While the daily rhythm in ventilation is largely shaped by the metabolic rate, less is known about whether ventilatory rhythms are altered in accordance with metabolism under different photoperiods. Here, we investigate the relationship between ventilation and metabolism under different photoperiods using whole-body plethysmography and indirect calorimetry. We find that the daily timing of ventilation is chiefly synchronized to dark onset and that light cues are important for maintaining daily ventilatory rhythms. Moreover, changes in ventilatory patterns are not paralleled by changes in oxygen consumption, energy expenditure, or respiratory exchange rate under different photoperiods. We conclude that ventilatory patterns are not only shaped by the metabolic rate and circadian timing but are also influenced by other light-driven factors. Collectively, these findings have clinical implications for the seasonal variations in sleep-disordered breathing found in individuals with obstructive sleep apnea