Physical Sciences and Mathematics Commons^™

Sigma Hole Potentials As Tools: Quantifying And Partitioning Substituent Effects, Kelling J. Donald, Nam Pham, Pranav Ravichandran

Chemistry Faculty Publications

Empirical substituent constants such as the Hammett parameters have found important utility in organic and other areas of chemistry. They are useful both in predicting the impact of substitutions on chemical processes and in rationalizing, after the fact, observations on chemical bonding and reactivity. We assess the impact of substitutions on mono-iodinated benzene rings and find that the modifications that substituents induce on the electrostatic potentials at the sigma hole on the terminal I center correlate strongly with established trends of common substituents. As an alternative to the experimental procedures involved in obtaining empirically based substituent constants, the computationally determined …

Emerging Consensus On Net Energy Paves The Way For Improved Integrated Assessment Modeling, Louis Delannoy, Matthieu Auzanneau, Baptiste Andrieu, Olivier Vidal, Pierre-Yves Longaretti, Emmanuel Prados, David J. Murphy, Roger W. Bentley, Michael Carbajales-Dale, Marco Raugei, Mikael Hook, Victor Court, Carey W. King, Florian Fizaine, Pierre Jacques, Matthew Kuperus Heun, Andrew Jackson, Charles Guay-Boutet, Emmanuel Aramendia, Jianliang Wang, Hugo Le Boulzec, Charles A.S. Hall

University Faculty Publications and Creative Works

Extracting, processing, and delivering energy requires energy itself, which reduces the net energy available to society and yields considerable socioeconomic implications. Yet, most mitigation pathways and transition models overlook net energy feedbacks, specifically related to the decline in the quality of fossil fuel deposits, as well as energy requirements of the energy transition. Here, we summarize our position across 8 key points that converge to form a prevailing understanding regarding EROI (Energy Return on Investment), identify areas of investigation for the Net Energy Analysis community, discuss the consequences of net energy in the context of the energy transition, and underline …

Drought In The Breadbasket Of America And The Influence Of Oceanic Teleconnections, Olivia G. Campbell, Gregory B. Goodrich

School of Natural Resources: Faculty Publications

From 1980 to 2020, drought events accounted for only 11.4% of the billion-dollar disasters in the United States (U.S.), yet caused the second-highest total amount in damages, at USD 236.6 billion. With the average cost of a drought being upwards of USD 9.5 billion, these natural disasters can create serious problems in agriculture. Drought is defined as a period of below-average precipitation that causes damage to agriculture and water supplies. Previous research has linked drought events in the U.S. Great Plains to oceanic teleconnections in the Pacific and Atlantic basins, indicating the influence of El Niño—Southern Oscillation (ENSO), the Pacific …

Data-Driven Decision Support Tool Co-Development With A Primary Health Care Practice Based Learning Network, Jacqueline K. Kueper, Jennifer Rayner, Sara Bhatti, Kelly Angevaare, Sandra Fitzpatrick, Paulino Lucamba, Eric Sutherland, Daniel J. Lizotte

Epidemiology and Biostatistics Publications

Background: The Alliance for Healthier Communities is a learning health system that supports Community Health Centres (CHCs) across Ontario, Canada to provide team-based primary health care to people who otherwise experience barriers to care. This case study describes the ongoing process and lessons learned from the first Alliance for Healthier Communities’ Practice Based Learning Network (PBLN) data-driven decision support tool co-development project.

Methods: We employ an iterative approach to problem identification and methods development for the decision support tool, moving between discussion sessions and case studies with CHC electronic health record (EHR) data. We summarize our work to date in …

Pathogenicity In Chickens And Turkeys Of A 2021 United States H5n1 Highly Pathogenic Avian Influenza Clade 2.3.4.4b Wild Bird Virus Compared To Two Previous H5n8 Clade 2.3.4.4 Viruses, Mary J. Pantin-Jackwood, Erica Spackman, Christina Leyson, Sungsu Youk, Scott A. Lee, Linda M. Moon, Mia K. Torchetti, Mary L. Killian, Julianna B. Lenoch, Darrell R. Kapczynski, David E. Swayne, David L. Suarez

United States Department of Agriculture Wildlife Services: Staff Publications

Highly pathogenic avian influenza viruses (HPAIVs) of subtype H5 of the Gs/GD/96 lineage remain a major threat to poultry due to endemicity in wild birds. H5N1 HPAIVs from this lineage were detected in 2021 in the United States (US) and since then have infected many wild and domestic birds. We evaluated the pathobiology of an early US H5N1 HPAIV (clade 2.3.4.4b, 2021) and two H5N8 HPAIVs from previous outbreaks in the US (clade 2.3.4.4c, 2014) and Europe (clade 2.3.4.4b, 2016) in chickens and turkeys. Differences in clinical signs, mean death times (MDTs), and virus transmissibility were found between chickens and …

Modeling And Analysis Of The Selective Lightning Strike Phenomenon At Locations In A Chemical Manufacturing Plant, Terver Maor

Doctoral Dissertations

This research was motivated by the overly simplified claims, from a previous study, that attempted to explain the cause of the reportedly repeated lightning strikes at certain locations in the chemical manufacturing plant. The findings, without any model, claimed that the electronic monitoring and control devices’ fire damage occurred, due to the raised electrical ground potential during lightning strikes. It proceeded that the raised electrical ground potential caused a power flow reversal, which exceeded the ratings of the affected electronic control modules, damaging them. This claim is inconsistent with published research work in the failure mechanisms of industrial control systems, …

Atomistic-Informed And Machine Learning-Assisted Crystal Plasticity Modeling For Materials Interface, Ibrahim Altarabsheh

Doctoral Dissertations

This dissertation presents a comprehensive study that addresses two critical challenges in the field of computational materials science and engineering from nano- to mesoscale. First, to overcome the well-acknowledged length scale limitation associated with atomistic simulations, a novel two-step approach is introduced for a probabilistic prediction of stress-strain curves in terms of material volume. The method combines Molecular Dynamics (MD) simulations and a multioutput Gaussian process (MOGP) with Bayesian analysis to model stress-strain behavior and predict stress and strain values. The model effectively captures the intricate three-stage curve shape exhibited in stress-strain plots, discerning key points such as yielding, hardening, …

Spectral Reflectance Indices Associated With Biomass Production Of Cold Stress Resistant White Clover Genotypes Collected In Argentine And Chilean Patagonia, Hernán Acuña, Luis Inostroza, Catalina Vásquez, Joel Ibañez

IGC Proceedings (1977-2023)

White clover (Trifolium repens L.) is the main forage legume species in grazing pastures in central and southern Chile and many other temperate regions of the world. Its growth rate is limited by low temperature, therefore, the selection of cold stress resistant genotypes is an important step for breeding cultivar to improve the clover growth curve and extend the grazing season in early spring and autumn. The main objective of this experiment was to determine the relationship between phenotypic traits, measured by the high-throughput phenotyping procedures based on canopy reflectance at different wavelengths (spectral reflectance indices, SRIs), and dry …

Stocking Rates And Carrying Capacity Of Grazing Lands In Bale Mountain National Park And Adjacent Areas, Southeast Ethiopia, Mohammed Abdulahi, Habtamu Teka, Hadis Tadele

IGC Proceedings (1977-2023)

Knowledge of grazing land carrying capacity and grazing pressure in and around protected areas is very crucial to support decision making over sustainable grazing levels and developing grazing pressure reduction strategies. However, there was lack of studies conducted on livestock carrying capacity and grazing pressure in the connected and dynamic system over a wider landscape scale. Hence, this study was conducted to estimate the livestock stocking rates and carrying capacity of grazing lands in Bale Mountain National Park (BMNP) and adjacent districts grazing lands, southeast Ethiopia. Three categories of data: Field surveys, satellite imagery, and socioeconomic secondary data were used. …

Grazing Effects On Soil Seed Banks: A Global Synthesis, Shi Yafei

IGC Proceedings (1977-2023)

Livestock grazing is a major disturbance affecting plant diversity and abundance in terrestrial ecosystems. The intermediate disturbance hypothesis (IDH) predicts that moderate-intensity grazing should produce the highest species diversity, while the Milchunas-Sala-Lauenroth (MSL) model posits that the IDH is valid only for mesic areas. However, it remains unclear how grazing affects soil seed bank and whether or not the IDH or MSL models are valid for soil seed bank communities. Here, we presented a global meta-analysis synthesizing 483 observations: we found that grazing had a negative effect on soil seed bank abundance, but did not alter seed bank richness. Further …

Effects Of Warming And Nitrogen Addition On Soil Enzyme Activities, X. Zhang, G. D. Han

IGC Proceedings (1977-2023)

Due to the intensification of human activities, global warming and increased atmospheric nitrogen deposition have become important driving factors of global change. In order to understand the effects of long-term warming and nitrogen application on soil physical and chemical properties and enzyme activities, the effects of warming and nitrogen application on grassland soil enzyme activities were measured. The aim was to reveal the response of enzyme activity in an Inner Mongolian desert steppe to long-term warming and nitrogen addition. The results were as follows. In 2018, nitrogen fertilization significantly increased soil dehydrogenase activity, and soil depth significantly affected soil urease, …

Additive Negative Effects Of Decadal Warming And Nitrogen Addition On Grassland Community Stability, Q. Wu, G. D. Han, S. X. Chang, H. Y. Ren

IGC Proceedings (1977-2023)

Much recent research has explored how global warming and increased nitrogen (N) deposition, two important components of global environmental changes, influence the structure and functioning of natural ecosystems. However, how ecosystem dynamics respond to the combination of long-term warming and N enrichment remains largely unexplored. The impact of warming and N addition on the temporal stability of plant communities were investigated in a decade-long field experiment. The study was conducted in northern China in a desert steppe, using a split-plot design with warming as the main-plot factor and N addition as the splitplot factor. Long-term warming and N addition had …

Plantain (Plantago Lanceolata L.) Growth Islimited Under Waterlogging, S. S. Wilson, Daniel J. Donaghy, D. J. Horne, Soledad Navarrete, P. D. Kemp

IGC Proceedings (1977-2023)

Plantain (Plantago lanceolata L.; PL) is becoming an increasingly important component of New Zealand dairy pastures because of its ability to reduce nitrogen losses to the environment. However, widespread suggestions of its poor persistence, have led to industry concern over its suitability for dairy systems. Anecdotal evidence suggests that PL does not cope well in waterlogged soil, yet there is little scientific literature relevant to this issue. Thus, the aim of this study was to investigate the impact of waterlogging stress on PL growth and survival. In a glasshouse, the performance of PL under waterlogging was evaluated against perennial …

Grass-Next – A Process-Based Model To Explore Nutrient And Carbon Dynamics In Topographically Complex Grazed Grasslands, F. Bilotto, Ronaldo Vibart, Alec D. Mackay, M. Harrison

IGC Proceedings (1977-2023)

Topographical features such as slope and aspect influence primary production, animal behavior and nutrient return to grazed grasslands. A new model was developed based on data collected during 40+ years of research in hill country landscapes, a long-term experiment on varying phosphorus (P) fertilizer rates and associated sheep stocking regimes. The Grass-NEXT model was able to simultaneously simulate total soil P (TSP), soil organic carbon (SOC) and total soil nitrogen (TSN) stock change and distribution in a topographically complex (hill country) landscape from 2003 to 2020. This model provided a basis for exploring, accounting, and reporting on changes in TSP, …

Discrepancies Between Observed And Predicted Climate-Driven Net Herbage Accumulation, Alec D. Mackay, Michael B. Dodd, K. J. Hutchinson, Ronaldo Vibart, F. Bilotto

IGC Proceedings (1977-2023)

The decline in net herbage accumulation (NHA) on the high phosphorus (P) fertilizer farmlet (HF) of a long-term P fertilizer and associated sheep grazing experiment in the last 25 years, aligns with the necessity to reduce the on-site nominal sheep stocking rates over the same period on this farmlet. This finding appears at odds with projected climate change driven modelling that forecast a largely positive outcome on pasture growth in summer moist environments. In this paper we explore the apparent discrepancies between the observed and predicted climate-driven NHA by using a climate-driven pasture growth module within a larger process-based model …

Beyond The Boom: Integrated Approaches To Managing Weeds And Brush, M. L. Treadwell, D. Burson

IGC Proceedings (1977-2023)

William Bray stated in his 1904 report, The Timber of the Edwards Plateau of Texas, "This struggle of the timberlands to capture the grasslands is an old warfare....it spreads like infection.” This trend is true today and especially pronounced in the Great Plains, where only 1/4 of the Great Plains’ original grasslands remains intact. Species like honey mesquite, honey locust, black locust, sumac, dogwood, post oak, winged elm, Siberian elm, salt cedar, huisache, Eastern redcedar, Ashe and redberry juniper, pricklypear, sericea lespedeza, and many other species represent alarming rates of spread and rapid establishment throughout Great Plains grasslands. Although, these …

Impact Of Brown Midrib Trait On The Decomposition Rate Of Sorghum-Sudangrass Residue In Pastures, C. D. Teutsch, B. P. Dooley, J. A. Bush, B. L. Hendrix

IGC Proceedings (1977-2023)

Sorghum-sudangrass (Sorghum bicolor var. bicolor x bicolor var. sudanense) can provide high quality summer grazing. Some varieties possess the brown midrib (BMR) trait which results in reduced lignin resulting in higher digestibility and animal performance. If microbes in the rumen can digest BMR sorghum-sudangrass more completely, then soil macro/micro flora and fauna may do so as well. This could result in nutrients being returned to the soil faster from plants containing the BMR trait. The objective of this study was to determine the decomposition rate of BMR and non-BMR sorghumsudangrass. The experimental design was a random complete with four …

Back To The Future: How Do We Get There From Here? Making Restoration Work, K. Swilling, E. Bisangwa, Pat D. Keyser

IGC Proceedings (1977-2023)

Extreme temperatures and long periods of drought observed with increasing frequency in the southeastern United States (U.S.) have demonstrated the need to develop more robust forage systems. Native warmseason grasses (NWSGs) are well adapted to fill this role, but their expanded use comes with several challenges, most notably, reliable establishment. The high cost of site preparation, high cost of seed, and slow initial growth of NWSG seedlings must be addressed to achieve increased adoption of NWSG in the eastern U.S. If these challenges are overcome, incorporating NWSG into grazing systems would benefit producers by filling the summer forage gap, mitigating …

Ecologically-Based Rodent Pest Management: Research Progress In Plateau Zokors On Qinghai-Tibetan Plateau, Su Junhu, Kang Yukun

IGC Proceedings (1977-2023)

Rodent management has been an ongoing global challenge. The emergence of ecologically based rodent management (EBRM) has improved a series of dilemmas in traditional rodent control that are poorly targeted, unsustainable, and environmentally harmful. The plateau zokor (Eospalax baileyi) is a key species in the Qinghai-Tibetan Plateau (QTP). In recent years, due to its high population density, this subterranean rodent has caused serious damage to the grassland ecosystems on the QTP. Currently, a series of explorations of EBRM on plateau zokors have been initiated. We review progress about EBRM on plateau zokor in this paper, which mainly includes …

Carbon-Nitrogen Ratios In Rangeland Soils In Various Agriculture Response Units In Three Watersheds In The Central Himalayas, India, Nanda Nautiyal, Vir Singh

IGC Proceedings (1977-2023)

CN ratios of rangeland soils in selected agriculture response units (ARUs) prevailing in three watersheds, Kosi, Alaknanda, and Pindar, in the Indian Central Himalayan mountains were analyzed. The ratios varied significantly (P

Challenges And Opportunities To Increase Carbon Sequestration In Subtropical Grazing Lands, Maria L. S. Silveira, João M. B. Vendramini, Elizabeth H. Boughton, Rosvel Bracho, Marta M. Kohmann, Abmael S. Cardoso

IGC Proceedings (1977-2023)

Livestock production has a significant environmental footprint. However, adoption of regenerative grazing land management practices can serve as a means of producing food with lower, or even net positive environmental impacts. Globally, much of the grazing land ecosystems are degraded due to improper management. This is particularly true in the southeastern US, where extensive areas of planted pastures are degraded due to inadequate nutrient and soil management. In this presentation, we will discuss the opportunities and challenges associated with increasing soil and ecosystem C sequestration in subtropical grazing lands through regenerative management practices. Introduction

Impact Of The Brachiaria Hybrids On Both Soil Health And Carbon Stock On Livestock Production, A. Silva, T. Madeira, D. Florian, E. A. Pizarro, R. N. Jauregui, G. Lobato, A. Santi, D. Fagundes, F. Pinheiro, A. Rieger, A. Cagliari

IGC Proceedings (1977-2023)

Pastures occupy 30% of Earth and 80% of the entire agricultural area of the planet. To ensure food to the world and contribute to the quality of the environment, pasture-based animal production systems will also have to undergo through a more intense evolution. The intensification of tropical grasslands is an important strategy of land utilization in developing countries, contributing to increase production and minimize environmental impact through the best management practices. In this sense, the use of Brachiaria hybrids represents an excellent option, since combining the best traits of different Brachiaria species, with higher nutritive value, forage, and seed yield. …

Grazing Effects On Soil Seed Banks: A Global Synthesis, Shi Yafei

IGC Proceedings (1977-2023)

Livestock grazing is a major disturbance affecting plant diversity and abundance in terrestrial ecosystems. The intermediate disturbance hypothesis (IDH) predicts that moderate-intensity grazing should produce the highest species diversity, while the Milchunas-Sala-Lauenroth (MSL) model posits that the IDH is valid only for mesic areas. However, it remains unclear how grazing affects soil seed bank and whether or not the IDH or MSL models are valid for soil seed bank communities. Here, we presented a global meta-analysis synthesizing 483 observations: we found that grazing had a negative effect on soil seed bank abundance, but did not alter seed bank richness. Further …

Effect Of Tan-Sheep Rotational Grazing On Soil Erosion In Typical Steppe On The Loess Plateau Of China, Shi Li-Yuan, Hou Fu-Jiang, Lou Shan-Ning

IGC Proceedings (1977-2023)

The effect of stocking rate on soil erosion has been at the forefront of water and soil conservation studies in recent years. By observing soil erosion caused by rainfall in typical steppe on the Loess Plateau in China, this research aimed to further explore the effect of stocking rate on soil erosion. The results showed that all the concerned indicators of soil erosion (runoff, runoff coefficient, soil loss, soil organic carbon loss, and soil total nitrogen and total phosphorus loss) had a significant (P < 0.001) positive linear correlation with stocking rate alone, and precipitation alone, while the indicators of runoff and soil loss had a significant (P < 0.01) negative linear correlation with typicalsteppe biomass (aboveground biomass, litter mass, and belowground biomass). Both stocking rate and precipitation had large significant (P < 0.01) effects on soil erosion via changes in aboveground biomass, litter mass, and soil organic carbon.

Effects Of Different Grazing Intensities On Grasshopper Communities In Stipa Breviflora Desert Steppe, Guodong Han, Tingting Shen

IGC Proceedings (1977-2023)

As a common method of grassland management, grazing plays an important role in grassland conservation. Grasshoppers and large herbivores are integral parts of grassland biodiversity and food webs. However, to some extent there is still room for further research on how grasshoppers cope with grazing by large herbivores. A field grazing experiment in Stipa breviflora desert steppe in Inner Mongolia, China to investigate the effects of sheep grazing intensity on the abundance and richness of locust population and community. The grazing experiment started in 2004, and the grasshopper population and community were investigated in 2021. The results showed that: Grazing …

Carbon Sequestration Potential Of Pasture-Based Systems Along An Altitudinal Gradient In The North-Western Himalayas, Harish Sharma, K. S. Pant, Rohit Bishist, Ravinder Sharma, Uday Sharma, M. K. Brahmi

IGC Proceedings (1977-2023)

The present investigation was carried out in the Chamba district of Himachal Pradesh (India) to identify the pasture-based land use systems being practiced by farmers and to find out their carbon sequestration potential along different altitudes. For carrying out the study, the area was divided into four altitudinal ranges viz., zone-I (amsl), zone-II (1000-1500 m amsl), zone-III (1500- 2500 m amsl) and zone-IV (> 2500 m amsl), according to agro-ecological zones in the state. Results revealed that the pasture-based systems practiced by the farmers in the altitudinal zone-I and zone-II were silvo-pasture and pastoral-silviculture, while, at altitudinal zone-III and zone-IV, …

Evaluating Functional Diversity As Potential Early-Warning Indicator Of Rangeland Degradation, L.-M. Schwarz, C. P. Carmona, M. C. Bilton, F. Munyebvu-Chambara, K. Behn, A. Linstädter

IGC Proceedings (1977-2023)

Droughts and overgrazing play a crucial role in the degradation of semi-arid rangelands. This is evident in the loss of palatable long-lived grass species and bush encroachment. Early warning indicators are needed to mitigate long-term degradation and decline in essential forage provision. Functional diversity provides valuable information on ecosystem health. However, functional diversity indices have not yet been tested regarding their applicability as early warning indicators, revealing non-linear threshold behaviour. We therefore examined the following questions: (1) How do functional diversity indices respond to grazing pressure? (2) Does land tenure affect the relationship between functional diversity and grazing pressure? (3) …

Integrating Grazing With 2,4-D And Florpyrauxifen To Control Broadleaf Weeds And Maintain Red Clover Productivity In Grass-Legume Pastures, M. J. Renz, G. M. Imhoff

IGC Proceedings (1977-2023)

In grass-legume pastures, 2,4-D-amine + florpyrauxifen-benzyl controls broadleaf weeds but red clover (Trifolium pratense L.) is eliminated. Grazing within a week prior to herbicide application is likely to reduce leaf surface area and may reduce red clover injury and maintain productivity. Experiments were conducted in 2020 and in 2021 to determine if red clover could be productive when 560 g ae ha^-1 2,4-D-amine + 6.3 g ae ha-1 of florpyrauxifen-benzyl with 1% v/v methylated seed oil applied in the spring was grazed before or after herbicide application. Grazing timings occurred 6, 4, or 2 days prior to herbicide …

Effect Of Simulated Precipitation On Soil Enzyme Activity Of Stipa Breviflora Desert Steppe, Ren Zihuana, Wang Zhongwub, Han Guodongb

IGC Proceedings (1977-2023)

The availability of nutrients for the grassland ecosystem is significantly influenced by changes in soil enzyme activity brought on by precipitation. Soil enzyme activity is an essential element controlling soil nutrient supply. This study used the Inner Mongolian desert steppe as its research subject and examined how different soil enzymes—urease, alkaline phosphatase, and invertase reacted to changing precipitation levels. According to the typical quantity of long-term precipitation in the area, four gradients of precipitation were established: 50% reduction (P1), control (P2), 50% increase (P3), and 100% increase (P4). First, the findings revealed that rising precipitation can boost invertase and alkaline …

Survival Rate And Morphological Growth Patterns Of Five Populations Of Festuca Dolichophylla Under Similar Conditions, Y. Paucar, E. R. Flores, H. M. Guillén, L. Aguirre

IGC Proceedings (1977-2023)

The majority of the natural grasslands of Perú are located in the Puna region; they are the only source of feed for raising animals in this area, and they also protect the soil from erosion. Festuca dolichophylla is a representative species with high productivity in this ecosystem. The aim of this study was to evaluate survival rate and morphological growth patterns of five populations of Festuca dolichophylla under similar conditions. Five accessions were obtained from each population: Pastales Huando Peasant Community - Huancavelica (CCPH), Lachocc South American Camelids Research and Development Center of the National University of Huancavelica (CIDCSL), Junin, …