Interactive Effects Of Sublethal Concentrations Of Fracking Biocides And Abandoned Mine Drainage On Amphipod Behavior, Kelly Lenhart

Electronic Theses and Dissertations

This thesis examined the sublethal effects of three pollutants, namely glutaraldehyde, 4,4-dimethyloxazolidine (DMO), and abandoned mine drainage (AMD), on amphipods. The primary objective was to investigate their combined effects on amphipods. The three pollutants, despite having the potential to combine in the environment, have not been studied to determine their potential for detrimental interactive effects which could result in unexpected environmental damage.

The research employed a series of experimental setups involving controlled exposure of amphipods to varying, putatively sublethal, concentrations of the chemicals of interest. Subsequently, effects were assessed via both behavioral and feeding assessments. To facilitate this analysis, novel …

Clean Energy Transition Threatens Indigenous Land Rights, Jonnathan M. Pulla

Capstones

Indigenous communities in Jujuy, Argentina are protesting a constitutional reform that could lead to their displacement without consultation or exposure to contamination from extractive projects. The story is told from the perspective of Milagros Lamas, a 19-year-old indigenous woman who joined the movement known as the Third Malón de la Paz.

Population Demography Of A Glacial-Relict Stream Fish Mediated Via Anthropogenic Alteration, Joseph M. Spooner

School of Natural Resources: Dissertations, Theses, and Student Research

Northern Pearl Dace Margariscus nachtriebi are a small-bodied glacial-relict fish species of greatest conservation need (SGCN) found throughout Canada and the northern United Sates. Their distribution within the Nebraska Sandhills Ecoregion is isolated from the northern core distribution of the species following the last glaciation period approximately 18,000 years ago. Headwater streams within the Nebraska Sandhills Ecoregion are predominately groundwater fed and provide the cool water temperatures needed to support Northern Pearl Dace and other glacial-relict SGCN. Headwater streams within the Nebraska Sandhills Ecoregion have been geomorphically altered through anthropogenic processes such as channelization whereby habitat homogenization has occurred. Evidence …

Habitat Heterogeneity In Nebraska Streams And Distribution Prediction For Tier-1 Cyprinids Using Multi-Scale Modeling Of Fluvial And Landscape Features, Connor P. Hart

School of Natural Resources: Dissertations, Theses, and Student Research

Multiscale environmental processes determine in-stream habitat conditions which drive species distributions. Habitat constitutes the physical template upon which ecological processes occur and species conduct life stage activities. Habitat heterogeneity promotes biodiversity of aquatic systems. Stream classification informs freshwater conservation by providing a useful framework to account for habitat heterogeneity, often based on landscape regions of similar environmental processes. A greater understanding of landscape-based classification frameworks as means to classify stream systems may improve understanding of drivers of biodiversity. Using Nebraska as a case study, on a statewide scale, objectives were 1) to characterize habitat availability for several at-risk fish species, …

Exploring Soil Microbial Dynamics In Southern Appalachian Forests: A Systems Biology Approach To Prescribed Fire Impacts, Saad Abd Ar Rafie

Doctoral Dissertations

Prescribed fires in Southern Appalachian forests are vital in ecosystem management and wildfire risk mitigation. However, understanding the intricate dynamics between these fires, soil microbial communities, and overall ecosystem health remains challenging. This dissertation addresses this knowledge gap by exploring selected aspects of this complex relationship across three interconnected chapters.

The first chapter investigates the immediate effects of prescribed fires on soil microbial communities. It reveals subtle shifts in porewater chemistry and significant increases in microbial species richness. These findings offer valuable insights into the interplay between soil properties and microbial responses during the early stages following a prescribed fire. …

Human Dimensions Of Woody Encroachment Management In Nebraska, Emily Rowen

School of Natural Resources: Dissertations, Theses, and Student Research

Woody plant encroachment (WPE) is a social-ecological problem that will challenge conservation professionals and agricultural producers to adapt their management strategies. This research first examined WPE from the perspective of individual conservation professionals through an online survey. Conservation professionals’ attitudes about adaptation to vegetation transitions, such as WPE, were of interest because these attitudes are one measure of how prepared this group is to respond to WPE. Hypothesized predictors of adaptation attitude were tested through linear regression modeling. These predictors included ecological change, observation of WPE, or risk perception. It was found that risk perception was the strongest predictor of …

The Essential Role Of Fossil Fuels In Combating Climate Change, Ivye Meyer

Op-Eds from ENSC230 Energy and the Environment: Economics and Policies

Fossil fuels have been essential to the living standards enjoyed by the industrialized and developed world. Since the Industrial Revolution, non-renewable sources, including coal, oil, and natural gas, have been our first choice in energy generation. Fossil fuels have also become appealing to developing nations, as they require inexpensive sources of energy to increase their standards of living. These factors contribute to fossil fuels comprising over 80 percent of the current global primary energy demand, undeniably making them a vital part of our daily lives. The necessity for upcoming change in energy production does not require the exclusion of fossil …

Navigating The Green Skies: Why Saf Is The Wrong Path To Take, Cameron Cannon

Op-Eds from ENSC230 Energy and the Environment: Economics and Policies

With its promise of a significant decrease in greenhouse gas emissions, sustainable aviation fuels, or SAFs, have been hailed as an environmentally friendly substitute for conventional aviation fuels. SAFs are made from sustainable resources such as plant biomass, waste oils, or agricultural wastes and are intended to mitigate environmental issues. On closer examination, though, this solution's intricacy becomes clear. Grab your mental compass and journey with me as we discover why SAFs would lead us the wrong way.

Why We Should Have More Walkable Cities, Alexander Huddleston

Op-Eds from ENSC230 Energy and the Environment: Economics and Policies

The walkable city is something that is seen all over Europe but is a rarity in the United States. The rise of cheap oil in the first half of the 20th century led to the expansion of the suburbs and a car culture that we just can’t get away from. Our cities are now so spread out, causing more and more pollution and damage done to our environment. There is a lot that we know about this issue and the solutions that we can get done to fix it. America is stuck in a car culture that is so hard …

Eminent Domain: Unconstitutional, Unjust, And Unnecessary, Ashley Norris

Op-Eds from ENSC230 Energy and the Environment: Economics and Policies

Perhaps the most important undertaking of our time is the ubiquity of sustainable energy vital for the continuation and improvement of living conditions worldwide. The utmost care must be taken with the means used to achieve this feat. The fossil fuel industry has used and abused eminent domain since its inception. Ironically, environmental advocates now propose the same means to a cleaner, greener end. The taking of private land for private development, regardless of intent, is unconstitutional, unjust, and unnecessary. The Fifth Amendment states: “…nor shall private property be taken for public use, without just compensation.”

As stated by the …

Sound Energy Could Change The World, Tyler Bugiel

Op-Eds from ENSC230 Energy and the Environment: Economics and Policies

The energy crisis is a problem that has been growing more concerning for many years, and yet there has not seemed to be a good solution to the problem. That being said, I think that there is a solution that has not been explored thoroughly enough, that solution being sound energy. Solar and wind are both energy systems that use natural resources and things that occur on a day to day basis to convert those things into energy, but sound has not been explored as much.

Ecological Impacts Of Restoring Fire-Grazing Interaction In Sandhills Prairie Through Patch-Burn Grazing, Nolan P. Sipe

School of Natural Resources: Dissertations, Theses, and Student Research

A Collaborative Adaptive Management (CAM) Project was started at the University of Nebraska in 2020 to address some of the key uncertainties related to the management of grasslands in the Nebraska Sandhills through stakeholder driven experiments and the adaptive management cycle. Patch-burn grazing was selected by CAM as a management tool to generate heterogeneity across the landscape and promote biodiversity while balancing economic and ecological trade-offs. The patch-burn grazing system was implemented with controlled burns in May of 2022 and March of 2023. Other parties in CAM will be examining the impact that patch-burn grazing has on forage and livestock …

Reimagining Large River Management Using The Resist–Accept–Direct (Rad) Framework In The Upper Mississippi River, Nicole K. Ward, Abigail J. Lynch, Erik A. Beever, Joshua Booker, Kristen L. Bouska, Holly Embke, Jeffrey N. Houser, John F. Kocik, Joshua Kocik, David J. Lawrence, Mary Grace Lemon, Doug Limpinsel, Madeline R. Magee, Bryan M. Maitland, Owen Mckenna, Andrew Meier, John M. Morton, Jeffrey D. Muehlbauer, Robert Newman, Devon C. Oliver, Heidi M. Rantala, Greg G. Sass, Aaron Shultz, Laura M. Thompson, Jennifer L. Wilkening

School of Natural Resources: Faculty Publications

Background: Large-river decision-makers are charged with maintaining diverse ecosystem services through unprecedented social-ecological transformations as climate change and other global stressors intensify. The interconnected, dendritic habitats of rivers, which often demarcate jurisdictional boundaries, generate complex management challenges. Here, we explore how the Resist–Accept–Direct (RAD) framework may enhance large-river management by promoting coordinated and deliberate responses to social-ecological trajectories of change. The RAD framework identifies the full decision space of potential management approaches, wherein managers may resist change to maintain historical conditions, accept change toward different conditions, or direct change to a specified future with novel conditions. In the Upper Mississippi …

Wavelet Compression As An Observational Operator In Data Assimilation Systems For Sea Surface Temperature, Bradley J. Sciacca

University of New Orleans Theses and Dissertations

The ocean remains severely under-observed, in part due to its sheer size. Containing nearly billion of water with most of the subsurface being invisible because water is extremely difficult to penetrate using electromagnetic radiation, as is typically used by satellite measuring instruments. For this reason, most observations of the ocean have very low spatial-temporal coverage to get a broad capture of the ocean’s features. However, recent “dense but patchy” data have increased the availability of high-resolution – low spatial coverage observations. These novel data sets have motivated research into multi-scale data assimilation methods. Here, we demonstrate a new assimilation approach …

The Impacts Of Tilled-In Biodegradable Plastic Mulch On Soil Microbial Communities, Corissa L. Martin

Masters Theses

Plastics mulch films are used in agriculture to help increase crop production by regulating soil water retention and soil temperature while also preventing weed growth. Despite these benefits, plastic mulches have led to higher levels of microplastic pollution as weathering occurs. In response to this issue, biodegradable plastic mulches (BDMs) have been introduced to help reduce plastic pollution as they are designed to be tilled into soil after each growing season to continue degradation. Degradation of these mulch films is dependent on climate and, in some areas, complete degradation can take years. Since some biodegradable plastic mulches are made of …

Accelerated Evolution Of Sars-Cov-2 In Free-Ranging White-Tailed Deer, Dillon S. Mcbride, Sofya K. Garushyants, John Franks, Andrew F. Magee, Steven H. Overend, Devra Huey, Amanda M. Williams, Seth A. Faith, Ahmed Kandeil, Sanja Trifkovic, Lance Miller, Trushar Jeevan, Anami Patel, Jacqueline M. Nolting, Michael J. Tonkovich, J. Tyler Genders, Andrew J. Montoney, Kevin Kasnyik, Timothy J. Linder, Sarah N. Bevins, Julianna B. Lenoch, Jeffrey C. Chandler, Thomas J. Deliberto, Eugene V. Koonin, Marc A. Suchard, Philippe Lemey, Richard J. Webby, Martha I. Nelson, Andrew S. Bowman

United States Department of Agriculture Wildlife Services: Staff Publications

The zoonotic origin of the COVID-19 pandemic virus highlights the need to fill the vast gaps in our knowledge of SARS-CoV-2 ecology and evolution in non-human hosts. Here, we detected that SARS-CoV-2 was introduced from humans into white-tailed deer more than 30 times in Ohio, USA during November 2021-March 2022. Subsequently, deer-to-deer transmission persisted for 2–8 months, disseminating across hundreds of kilometers. Newly developed Bayesian phylogenetic methods quantified how SARS-CoV-2 evolution is not only three-times faster in white-tailed deer compared to the rate observed in humans but also driven by different mutational biases and selection pressures. The long-term effect of …

Rapid Evolution Of A(H5n1) Influenza Viruses After Intercontinental Spread To North America, Ahmed Kandeil, Christopher Patton, Jeremy C. Jones, Trushar Jeevan, Walter N. Harrington, Sanja Trifkovic, Jon P. Seiler, Thomas Fabrizio, Karlie Woodard, Jasmine C. Turner, Jeri Carol Crumpton, Lance Miller, Adam Rubrum, Jennifer Debeauchamp, Charles J. Russell, Elena A. Govorkova, Peter Vogel, Mia Kim-Torchetti, Yohannes Berhane, David Stallknecht, Rebecca Poulson, Lisa Kercher, Richard J. Webby

United States Department of Agriculture Wildlife Services: Staff Publications

Highly pathogenic avian influenza A(H5N1) viruses of clade 2.3.4.4b underwent an explosive geographic expansion in 2021 among wild birds and domestic poultry across Asia, Europe, and Africa. By the end of 2021, 2.3.4.4b viruses were detected in North America, signifying further intercontinental spread. Here we show that the western movement of clade 2.3.4.4b was quickly followed by reassortment with viruses circulating in wild birds in North America, resulting in the acquisition of different combinations of ribonucleoprotein genes. These reassortant A(H5N1) viruses are genotypically and phenotypically diverse, with many causing severe disease with dramatic neurologic involvement in mammals. The proclivity of …

Beyond The Tide: A Comprehensive Guide To Sea-Level-Rise Inundation Mapping Using Foss4g, Levente Juhasz, Jinwen Xu, Randall W. Parkinson

GIS Center

No abstract provided.

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 …

Raccoon Spatial Ecology In The Rural Southeastern United States, Jacob E. Hill, Madison L. Miller, James L. Helton, Richard B. Chipman, Amy T. Gilbert, James C. Beasley, Guha Dharmarajan, Olin E. Rhodes Jr.

United States Department of Agriculture Wildlife Services: Staff Publications

The movement ecology of raccoons varies widely across habitats with important implications for the management of zoonotic diseases such as rabies. However, the spatial ecology of raccoons remains poorly understood in many regions of the United States, particularly in the southeast. To better understand the spatial ecology of raccoons in the southeastern US, we investigated the role of sex, season, and habitat on monthly raccoon home range and core area sizes in three common rural habitats (bottomland hardwood, upland pine, and riparian forest) in South Carolina, USA. From 2018–2022, we obtained 264 monthly home ranges from 46 raccoons. Mean monthly …

Raccoon Spatial Ecology In The Rural Southeastern United States, Jacob E. Hill, Madison L. Miller, James L. Helton, Richard B. Chipman, Amy Gilbert, University Of Georgia, Guha Dharmarajan, Olin E. Rhodes Jr.

United States Department of Agriculture Wildlife Services: Staff Publications

The movement ecology of raccoons varies widely across habitats with important implications for the management of zoonotic diseases such as rabies. However, the spatial ecology of raccoons remains poorly understood in many regions of the United States, particularly in the southeast. To better understand the spatial ecology of raccoons in the southeastern United States, we investigated the role of sex, season, and habitat on monthly raccoon home range and core area sizes in three common rural habitats (bottomland hardwood, upland pine, and riparian forest) in South Carolina, USA. From 2018–2022, we obtained 264 monthly home ranges from 46 raccoons. Mean …

Precipitation And Greenness In Pastoral Lands Of East Turkana, Kenya, Paul Akpejeluh

School of Natural Resources: Dissertations, Theses, and Student Research

Pastoralism has long supported livelihoods and provided essential ecosystem services in landscapes of East Africa. Vegetation productivity is central to the functioning of pastoral systems but may be affected by changes in climate and landuse. Vegetation monitoring is important for understanding the effects of global change in pastoral lands; however, it can be time and resource intensive. Remote sensing provides opportunities for efficient multi-scale monitoring of vegetation and climatic drivers. In this thesis, I explore the utility of satellite and UAV remote sensing for monitoring vegetation and precipitation trends and relationships in the East of Lake Turkana Region of northern …

Skin Lipids Alone Enable Conspecific Tracking In An Invasive Reptile, The Argentine Black And White Tegu Lizard (Salvator Merianae), M. Rockwell Parker, Eric A. Tillman, Lauren A. Nazarian, Megan L. Barlowe, Julianna M. Lincoln, Bryan M. Kluever

United States Department of Agriculture Wildlife Services: Staff Publications

Locating potential mates in non-native habitats is one of the most important challenges faced by invasive vertebrate species. The Argentine black and white tegu lizard (Salvator merianae) is a major invasive reptile species in the contiguous United States and is rapidly expanding its range across Florida and the Southeast, in part due to inadequate management strategies and tools. Because a wide array of reptiles, especially squamates (snakes and lizards), have been well-studied for their reliance on chemical cues to locate conspecifics, our project aimed to isolate chemical cues from tegus and assess the ability of adult males and …

Review Of Harmful Algal Bloom Effects On Birds With Implications For Avian Wildlife In The Chesapeake Bay Region, Barnett A. Rattner, Catherine E. Wazniak, Julia S. Lankton, Peter C. Mcgowan, Serguei V. Drovetski, Todd A. Egerton

United States Geological Survey: Staff Publications

The Chesapeake Bay, along the mid-Atlantic coast of North America, is the largest estuary in the United States and provides critical habitat for wildlife. In contrast to point and non-point source release of pesticides, metals, and industrial, personal care and household use chemicals on biota in this watershed, there has only been scant attention to potential exposure and effects of algal toxins on wildlife in the Chesapeake Bay region. As background, we first review the scientific literature on algal toxins and harmful algal bloom (HAB) events in various regions of the world that principally affected birds, and to a lesser …

Understanding The Soil Water Dynamics During Excess And Deficit Rainfall Conditions Over The Core Monsoon Zone Of India, Mangesh M. Goswami, Milind Mujumdar1, Bhupendra Bahadur Singh, Madhusudan Ingale, Naresh Ganeshi, Manish Ranalkar, Trenton E. Franz, Prashant Srivastav, Dev Niyogi, R Krishnan, S N. Patil

School of Natural Resources: Faculty Publications

Observations of soil moisture (SM) during excess and deficit monsoon seasons between 2000 to 2021 present a unique opportunity to understand the soil water dynamics (SWD) over core monsoon zone (CMZ) of India. This study aims to analyse SWD by investigating the SM variability, SM memory (SMM), and the coupling between surface and subsurface SM levels. Particularly intriguing are instances of concurrent monsoonal extremes, which give rise to complex SWD patterns. Usually, it is noted that a depleted convective activity and persistence of higher temperatures during the pre-monsoon season leads to lower SM, while monsoon rains and post-monsoon showers support …

Reducing Uncertainty In Sea-Level Rise Prediction: A Spatial-Variability-Aware Approach, Subhankar Ghosh, Shuai An, Arun Sharma, Jayant Gupta, Shashi Shekhar, Aneesh Subramanian

I-GUIDE Forum

Given multi-model ensemble climate projections, the goal is to accurately and reliably predict future sea-level rise while lowering the uncertainty. This problem is important because sea-level rise affects millions of people in coastal communities and beyond due to climate change's impacts on polar ice sheets and the ocean. This problem is challenging due to spatial variability and unknowns such as possible tipping points (e.g., collapse of Greenland or West Antarctic ice-shelf), climate feedback loops (e.g., clouds, permafrost thawing), future policy decisions, and human actions. Most existing climate modeling approaches use the same set of weights globally, during either regression or …

H5n1 Highly Pathogenic Avian Influenza Clade 2.3.4.4b In Wild And Domestic Birds: Introductions Into The United States And Reassortments, December 2021–April 2022, Sungsu Youk, Mia Kim Torchetti, Kristina Lantz, Julianna B. Lenoch, Mary Lea Killian, Christina Leyson, Sarah N. Bevins, Krista Dilione, Hon S. Ip, David E. Stallknecht, Rebecca L. Poulson, David L. Suarez, David E. Swayne, Mary J. Pantin-Jackwood

United States Department of Agriculture Wildlife Services: Staff Publications

Highly pathogenic avian influenza viruses (HPAIVs) of the A/goose/Guangdong/1/1996 lineage H5 clade 2.3.4.4b continue to have a devastating effect on domestic and wild birds. Full genome sequence analyses using 1369 H5N1 HPAIVs detected in the United States (U.S.) in wild birds, commercial poultry, and backyard flocks from December 2021 to April 2022, showed three phylogenetically distinct H5N1 virus introductions in the U.S. by wild birds. Unreassorted Eurasian genotypes A1 and A2 entered the Northeast Atlantic states, whereas a genetically distinct A3 genotype was detected in Alaska. The A1 genotype spread westward via wild bird migration and reassorted with North American …

Limited Accumulation And Persistence Of An Influenza A Virus In Tadpole Snails (Physa Spp.), Paul T. Oesterle, J. Jeffrey Root, Darcy S.O. Mora, Heather Schneider, Alan B. Franklin, Kathryn P. Huyvaert

United States Department of Agriculture Wildlife Services: Staff Publications

Waterfowl infected with avian influenza A viruses (IAVs) shed infectious virus into aquatic environments, providing a mechanism for transmission among waterfowl, while also exposing the entire aquatic ecosystem to the virus. Aquatic invertebrates such as freshwater snails are likely exposed to IAVs in the water column and sediment. Freshwater snails comprise a significant portion of some waterfowl species’ diets, so this trophic interaction may serve as a novel route of IAV transmission. In these experiments, tadpole snails (Physa spp.) were exposed to a low-pathogenicity IAV (H3N8) to determine whether snails can accumulate the virus and, if so, how long virus …

Response Of Lake Metabolism To Catchment Inputs Inferred Using High-Frequency Lake And Stream Data From Across The Northern Hemisphere, Jessica R. Corman, Jacob A. Zwart, Jennifer Klug, Denise A. Bruesewitz, Elvira De Eyto, Marcus Klaus, Lesley B. Knoll, James A. Rusak, Michael J. Vanni, María Belén Alfonso, Rocio Luz Fernandez, Huaxia Yao, Kari Austnes, Raoul-Marie Couture, Heleen A. De Wit, Jan Karlsson, Alo Laas

School of Natural Resources: Faculty Publications

In lakes, the rates of gross primary production (GPP), ecosystem respiration (R), and net ecosystem production (NEP) are often controlled by resource availability. Herein, we explore how catchment vs. within lake predictors of metabolism compare using data from 16 lakes spanning 39^oN to 64^oN, a range of inflowing streams, and trophic status. For each lake, we combined stream loads of dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) with lake DOC, TN, and TP concentrations and high frequency in situ monitoring of dissolved oxygen. We found that stream load stoichiometry indicated lake stoichiometry …

Dual Activation Of Peroxymonosulfate Using Mnfe2O4/G‑C3N4 And Visible Light For The Efficient Degradation Of Steroid Hormones: Performance, Mechanisms, And Environmental Impacts, Kitipong Poomipuen, Chainarong Sakulthaew, Chanat Chokejaroenrat, Athaphon Angkaew, Kanidrawee Techauay, Thapanee Poompoung, Kanokwan Teingtham, Piyaporn Phansak, Piyangkun Lueangjaroenkit, Daniel D. Snow

School of Natural Resources: Faculty Publications

Single activation of peroxymonosulfate (PMS) in a homogeneous system is sometimes insufficient for producing reactive oxygen species (ROS) for water treatment applications. In this work, manganese spinel ferrite and graphitic carbon nitride (MnFe₂O₄/g-C₃N₄; MnF) were successfully used as an activator for PMS under visible light irradiation to remove the four-mostdetected- hormone-contaminated water under different environmental conditions. The incorporation of g-C₃N₄ in the nanocomposites led to material enhancements, including increased crystallinity, reduced particle agglomeration, amplified magnetism, improved recyclability, and increased active surface area, thereby facilitating the PMS activation and electron …