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University of Arkansas, Fayetteville

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Articles 181 - 210 of 2033

Full-Text Articles in Engineering

Polymeric Biomaterials Approaches For Engineering The In Vitro Cellular Microenvironment For Mscs, Mahsa Letter-Mahsa Haseli May 2023

Polymeric Biomaterials Approaches For Engineering The In Vitro Cellular Microenvironment For Mscs, Mahsa Letter-Mahsa Haseli

Graduate Theses and Dissertations

Cell therapy is a technology that relies on replacing diseased or dysfunctional cells with healthy functioning ones. One of the cells used for such advanced therapies are stem cells, owing to their ability to differentiate into specific cells required for repairing damaged or defective tissues or cells. The majority of cell-based products are intended to transiently persist in the patient, secreting factors which then allow the patient’s body to heal; in these products, the cells are subsequently eliminated from the body. Furthermore, unique manufacturing platforms, in addition to novel commercialization strategies, will be required to create a successful, sustainable cell …

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Improving Tribological Properties Of Polydopamine/Polytetrafluoroethylene Coatings Through Incorporating Core-Shell Nanoparticles And Laser Surface Texturing, Firuze Soltani-Kordshuli May 2023

Improving Tribological Properties Of Polydopamine/Polytetrafluoroethylene Coatings Through Incorporating Core-Shell Nanoparticles And Laser Surface Texturing, Firuze Soltani-Kordshuli

Graduate Theses and Dissertations

Polytetrafluoroethylene (PTFE) is a widely used polymer that has unique properties such as chemical and temperature resistance, corrosion resistance, low maintenance cost, and a very low coefficient of friction (COF). These distinctive properties have made PTFE a promising candidate for industrial applications where surfaces are in relative motion. PTFE can be utilized as a thin film solid lubricant to significantly reduce the friction between moving surfaces. However, PTFE coatings have low cohesion and poor adhesion to the substrate resulting in its low wear resistance. This fact limits the application of PTFE coatings in load-bearing situations. To address these limitations, an …

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Effect Of Human Decellularized Skeletal Muscle On Recovery From Volumetric Muscle Loss Injury, Jacob Schluns May 2023

Effect Of Human Decellularized Skeletal Muscle On Recovery From Volumetric Muscle Loss Injury, Jacob Schluns

Graduate Theses and Dissertations

Volumetric muscle loss (VML) overwhelms muscle’s robust capacity for regeneration. A key event in the etiology of VML injury is the bulk loss of structural cues provided by the underlying extracellular matrix (ECM). While muscle is a highly structured tissue, with cell and ECM alignment in the direction of contractile force production, the impact of scaffold alignment on recovery remains unclear. Bulk human decellularized skeletal muscle (DSM) tissues were sectioned into 10 x 1-2 mm fibers. VML defects were repaired using multi-fiber implants consisting of approximately 8 fibers per defect arranged into two layers. Fibers were oriented 1) to the …

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Analysis Of An Isolated Bidirectional Ćuk Converter, Yeny Hau Chen May 2023

Analysis Of An Isolated Bidirectional Ćuk Converter, Yeny Hau Chen

Graduate Theses and Dissertations

The objective of this thesis is to perform an analysis of the isolated bidirectional Ćuk dc-dc converter topology and demonstrate the advantages and operation of this configuration through simulations using MATLAB/SimulinkTM and measurements collected from a 1.5-kW prototype tested at the Engineering Research Center (ENRC) laboratory of the University of Arkansas. The idea of integrating an active-clamp snubber circuit on each side of the converter, proposed by Dr. Sudip Mazumder from the University of Illinois, Chicago, limits the additional voltage stresses on the components due to the energy from the transformer’s leakage inductance. This is studied in this thesis to …

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Understanding And Tuning Magnetism In Van Der Waals Magnetic Compounds, Rabindra Basnet May 2023

Understanding And Tuning Magnetism In Van Der Waals Magnetic Compounds, Rabindra Basnet

Graduate Theses and Dissertations

The recently discovered two-dimensional (2D) magnetism has attracted intensive attention due to possible magnetic phenomenon arising from 2D magnetism and their promising potential for spintronics applications. The advances in 2D magnetism have motivated the study of layered magnetic materials, and further enhanced our ability to tune their magnetic properties. Among various layered magnets, tunable magnetism has been widely investigated in metal thiophosphates MPX3. It is a class of magnetic van der Waals (vdW) materials with antiferromagnetic ordering persisting down to atomically thin limit. Their magnetism originates from the localized moments due to 3d electrons in transition metal ions. So, their …

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Automation Of Life Cycle Assessment, Jacob Hickman May 2023

Automation Of Life Cycle Assessment, Jacob Hickman

Graduate Theses and Dissertations

An automation program, named Jacob LCA, was created to help perform life cycle assessment (LCA). The program uses a template file to perform controlled and consistently ordered actions with the LCA program, SimaPro, and effectively removes the need for manual user input. It can be set to run using data from one or more life cycle inventory (LCI) files, which allows for rapid iteration and testing of data. It also partially addresses some of the limitations of LCA by establishing a procedure through which temporal and spatial variations in data can be integrated into LCI files and then passed to …

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On The Micro-Mechanical Property Characterization And Bulk-Volume Behavior Prediction Of Additively Manufactured 17-4 Ph Stainless Steels, David González-Niño May 2023

On The Micro-Mechanical Property Characterization And Bulk-Volume Behavior Prediction Of Additively Manufactured 17-4 Ph Stainless Steels, David González-Niño

Graduate Theses and Dissertations

Selective laser melting is an additive manufacturing technology that opens the possibility to manufacture components with complex geometries that are difficult with traditional manufacturing techniques which could benefit engineering applications such as aviation or structural engineering. However, the lack of a reliable universal predictive model for selective laser melting components could impede the full implementation in industrial applications. Therefore, this dissertation investigates the mechanical behavior of selective laser melting 17-4 PH stainless steel under ultra-low cycle fatigue regime and propose a novel micro-mechanical based modeling using statistical and representative volume element. The first phase of this project examined the mechanical …

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Experimental Design For Determining The Cyclic Behavior Of Skewed Reduced Beam Section Moment Connections Having Composite Slabs, Paul Chabaud May 2023

Experimental Design For Determining The Cyclic Behavior Of Skewed Reduced Beam Section Moment Connections Having Composite Slabs, Paul Chabaud

Graduate Theses and Dissertations

This paper details the experimental design for determining the cyclic behavior of skewed Reduced Beam Section (RBS) moment connections having composite slabs. The effects of composite concrete slabs on skewed RBS connections subjected to cyclic seismic prequalification loading are addressed in this test setup. Full-scale double-sided RBS SMF specimens representing both interior and exterior column connections are designed and fabricated in this work. Experimental test fixturing and a lateral load application setup within the existing Grady E. Harvell Civil Engineering Research and Education Center (CEREC) are designed. All cyclic loading protocols required for the prequalification testing are described herein. Prequalification …

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Efficient Routing For Disaster Scenarios In Uncertain Networks: A Computational Study Of Adaptive Algorithms For The Stochastic Canadian Traveler Problem With Multiple Agents And Destinations, Neel Chanchad May 2023

Efficient Routing For Disaster Scenarios In Uncertain Networks: A Computational Study Of Adaptive Algorithms For The Stochastic Canadian Traveler Problem With Multiple Agents And Destinations, Neel Chanchad

Graduate Theses and Dissertations

The primary objective of this research is to develop adaptive online algorithms for solving the Canadian Traveler Problem (CTP), which is a well-studied problem in the literature that has important applications in disaster scenarios. To this end, we propose two novel approaches, namely Maximum Likely Node (MLN) and Maximum Likely Path (MLP), to address the single-agent single-destination variant of the CTP. Our computational experiments demonstrate that the MLN and MLP algorithms together achieve new best-known solutions for 10,715 instances. In the context of disaster scenarios, the CTP can be extended to the multiple-agent multiple-destination variant, which we refer to as …

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Development Of Self-Stressing Ultra High-Performance Concrete Using Expansive Chemical Admixtures, Lane Edwards May 2023

Development Of Self-Stressing Ultra High-Performance Concrete Using Expansive Chemical Admixtures, Lane Edwards

Graduate Theses and Dissertations

This study investigated the effects of expansive chemical admixtures on ultra-high performance concrete (UHPC) and self-stressing mechanisms. A literature review was performed to determine different types of expansive admixtures for feasibility of the self-prestressing concept. Ultimately it was decided that type-k cement, made by combining Komponent admixture with conventional UHPC, was the most suitable option due to its effects on wet and hardened concrete properties. Mix designs with varying amounts of Komponent were developed to test the effects the admixture had on various properties. Tested properties included, workability, compressive strength, expansion, short-term shrinkage, long-term shrinkage, and developed prestress. The development …

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Improving Classification In Single And Multi-View Images, Hadi Kanaan Hadi Salman May 2023

Improving Classification In Single And Multi-View Images, Hadi Kanaan Hadi Salman

Graduate Theses and Dissertations

Image classification is a sub-field of computer vision that focuses on identifying objects within digital images. In order to improve image classification we must address the following areas of improvement: 1) Single and Multi-View data quality using data pre-processing techniques. 2) Enhancing deep feature learning to extract alternative representation of the data. 3) Improving decision or prediction of labels. This dissertation presents a series of four published papers that explore different improvements of image classification. In our first paper, we explore the Siamese network architecture to create a Convolution Neural Network based similarity metric. We learn the priority features that …

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Mitral Valve Imaging And Biomechanics: A Workflow Towards Computational Modeling And Validation, Sam Stephens May 2023

Mitral Valve Imaging And Biomechanics: A Workflow Towards Computational Modeling And Validation, Sam Stephens

Graduate Theses and Dissertations

The mitral valve serves a critical role in healthy cardiac function by ensuring the unidirectional flow of oxygenated blood from the left atrium into the left ventricle. It experiences the highest pressures found within the heart and its closure is the result of a complex interaction of several different structures that, furthermore, are unique to each individual. Despite the valve’s vital role however, the specific function of these constituent structures is not fully understood. This, confounded by its asymmetric, personalized nature, make surgical interventions for the mitral valve far less effective than for its neighboring aortic valve. Efforts to overcome …

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Riverine Commons And Institute Framework Plan, Community Design Center Feb 2023

Riverine Commons And Institute Framework Plan, Community Design Center

Project Reports

The nonprofit Watershed Conservation Resource Center is restoring a 98-acre riparian wetland landscape near downtown Fayetteville as a River Commons and Institute. The Framework Plan combines watershed restoration with architecture and urban design to house a river education center, a visitor interpretive center, walking trails, passive recreation facilities including bird watching and canoeing, and outdoor heritage exhibitions. The Plan operates at the intersection of anthropology, ecology, and design in developing a lasting and robust riverine knowledge fund across space and time.

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Instructions To Authors, Academy Editors Jan 2023

Instructions To Authors, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Journal Of The Arkansas Academy Of Science Volume 77, Academy Editors Jan 2023

Journal Of The Arkansas Academy Of Science Volume 77, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Journal Acknowledgements And Editorial Board, Academy Editors Jan 2023

Journal Acknowledgements And Editorial Board, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Business Meeting Report (Secretary's And Treasurer's Report), Academy Editors Jan 2023

Business Meeting Report (Secretary's And Treasurer's Report), Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Academy Presidents And Institutional Members, Academy Editors Jan 2023

Academy Presidents And Institutional Members, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Histomorphology Of The Distal Urogenital Ducts In The Male Northern Crawfish Frog, Rana Areolata Circulosa (Anura: Ranidae), S.E. Trauth, R.G. Neal Jan 2023

Histomorphology Of The Distal Urogenital Ducts In The Male Northern Crawfish Frog, Rana Areolata Circulosa (Anura: Ranidae), S.E. Trauth, R.G. Neal

Journal of the Arkansas Academy of Science

We examined the microanatomy of the distal urogenital ducts in the male Northern Crawfish Frog (Rana areolata circulosa) from a small sample (n = 5) collected in February and March from central Arkansas over a 5-year period (2017–2022). Specifically, we sought information on the following structures: (1) the paired Wolffian (urogenital) ducts caudally from the kidneys to their merging with the urodeum of the cloaca, (2) the paired seminal vesicles (sperm storage structures), and (3) the paired Müllerian ducts and glands. This study provides new information on these urogenital ducts and promotes a clearer understanding of this anatomical region for …

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Keynote Address And Meeting Program, Academy Editors Jan 2023

Keynote Address And Meeting Program, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Rare Birds In Arkansas: Historical Observations And New Records, R. Tumlison, R. Kannan Jan 2023

Rare Birds In Arkansas: Historical Observations And New Records, R. Tumlison, R. Kannan

Journal of the Arkansas Academy of Science

Diligent members of birding communities are quick to report rare sightings of birds, which often lead to multiple observations and photographic documentation. Verified reports and images of birds in Arkansas are curated by the Arkansas Audubon Society (AAS), which has led to an appreciation of which species are common versus rare. We gathered historic (literature) and more recent unpublished records of rare birds (those with fewer than 10 reports, per AAS) to document the historic and current state of knowledge of those species. Currently, there are a total of 425 species of birds reported in Arkansas, of which 54 are …

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Table Of Contents, Academy Editors Jan 2023

Table Of Contents, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

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Investigation Of A Recent Landslide In Fort Smith, Arkansas, D. Mayo, M.J. Thomas, A. Burns, J. Pruitt, P. Karr Jan 2023

Investigation Of A Recent Landslide In Fort Smith, Arkansas, D. Mayo, M.J. Thomas, A. Burns, J. Pruitt, P. Karr

Journal of the Arkansas Academy of Science

A morphologically youthful slope failure, herein referred to as the Landfill Landslide, was identified in a remote section of the City of Fort Smith Landfill, and permission was obtained to investigate. The slide on a deforested, NW-facing 27% slope beneath a linear head scarp about 200 meters long. One end of the head scarp curves abruptly downhill and transforms into a distinct lateral scarp greater than 100 meters long. The surface of the slide is about 24,000 m2 (6 acres) in area and is easily distinguished from adjacent intact slopes by its hummocky morphology and transverse ridges and valleys. The …

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Determination Of Fatty Acid Concentrations In Various Strains Of Freshwater Green Picoplankton Algae (Class Eustigmatophyceae), P. Ashcraft, R. Jacks, B. Martinez, J. Rodriguez, A.B. Burns, A. Gurnsey, L. Taylor, A. Teague, J. Totty, V.L. Fox, A. Williams Jan 2023

Determination Of Fatty Acid Concentrations In Various Strains Of Freshwater Green Picoplankton Algae (Class Eustigmatophyceae), P. Ashcraft, R. Jacks, B. Martinez, J. Rodriguez, A.B. Burns, A. Gurnsey, L. Taylor, A. Teague, J. Totty, V.L. Fox, A. Williams

Journal of the Arkansas Academy of Science

Algae are of scientific and commercial interest due to their ease of culture and high fatty acid content. The extracted fatty acids from these phytoplankton may potentially be used as an additional test for phylogenetic classification of new algal strains (Tonon et al. 2002), as well as in a supplement for human consumption and producing next-generation biofuels. Of interest is the fatty acid content contained within various algal isolates within the class Eustigmatophyceae. Algal strains were collected and isolated from locations in Lake Chicot in Arkansas, Tower Pond and Lake Itasca at Itasca State Park in Minnesota, and Thayer Lake …

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Determining Mating Type And Species Of A Natural Isolate Of Dictyostelium Using Molecular Techniques And Sexual Crosses, S.N. Baviskar, C. Catron, H. Jenkins, M. Smith Jan 2023

Determining Mating Type And Species Of A Natural Isolate Of Dictyostelium Using Molecular Techniques And Sexual Crosses, S.N. Baviskar, C. Catron, H. Jenkins, M. Smith

Journal of the Arkansas Academy of Science

Cellular slime molds, Dictyostelium, are bactivorous, soil-dwelling amoebae. When food is available, cells reproduce asexually by binary fission. Under certain environmental conditions, such as darkness and humidity, Dictyostelium reproduces sexually. The sexual cycle is uniquely social and has unusual features. First, sexual reproduction in most eukaryotes usually involves fusion of two gametes. But, in Dictyostelium, triparental inheritance is observed (Bloomfield et al. 2019), in which gamete fusion involves more than two gametes. Second, most eukaryotic species have two sexes or mating types, but Dictyostelium species are known to have more than two mating types. Even though Dictyostelium species show variations …

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New Host Records Of Apicomplexan Blood Parasites (Haemogregarinidae And Hepatozoidae) Infecting Two Reptiles (Testudines; Ophidia) From Arkansas, C.T. Mcallister, H.W. Robison Jan 2023

New Host Records Of Apicomplexan Blood Parasites (Haemogregarinidae And Hepatozoidae) Infecting Two Reptiles (Testudines; Ophidia) From Arkansas, C.T. Mcallister, H.W. Robison

Journal of the Arkansas Academy of Science

Relatively few records of apicomplexan blood parasites from reptiles in Arkansas have been published although the effects of these parasites on reptilian health may be of concern. Using photomicrographs we describe the morphotypes of parasite gamonts found in blood samples from the Midland smooth softshell turtle, Apalone mutica mutica, and a western Milksnake Lampropeltis gentilis from Arkansas. The turtle possessed four distinct morphological gamont forms of a Haemogregarina sp. The snake possessed two morphological forms of gamonts of a Hepatozoon sp. Both infections are new host records and the western milksnake has not been described as a host elsewhere for …

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Noteworthy Parasites (Trematoda, Cestoda, Phthiraptera) Of Three Birds (Aves: Passeriformes; Pelecaniformes; Piciformes) From Arkansas, C.T. Mcallister, H.W. Robison Jan 2023

Noteworthy Parasites (Trematoda, Cestoda, Phthiraptera) Of Three Birds (Aves: Passeriformes; Pelecaniformes; Piciformes) From Arkansas, C.T. Mcallister, H.W. Robison

Journal of the Arkansas Academy of Science

Between November 2020 and March 2021, three species of birds, one each of a tufted titmouse (Baeolophus bicolor), pileated woodpecker (Dryocopus pileatus), and great blue heron (Ardea herodias) were salvaged from Lawrence and Polk counties, Arkansas, and examined for parasites. Found were four taxa of parasites, including a dicrocoeliid trematode, a cyclophyllidean cestode, and species of philopterid and menoponid lice. We document new host and distributional records for these parasites from select birds of the state.

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Helminth Parasites Of Northern Cottonmouth, Agkistrodon Piscivorus (Ophidia: Viperidae), From Arkansas, C.T. Mcallister, C.R. Bursey, H.W. Robison Jan 2023

Helminth Parasites Of Northern Cottonmouth, Agkistrodon Piscivorus (Ophidia: Viperidae), From Arkansas, C.T. Mcallister, C.R. Bursey, H.W. Robison

Journal of the Arkansas Academy of Science

The Northern cottonmouth, Agkistrodon piscivorus is a large, semiaquatic viperid snake found statewide in Arkansas. Although a great deal has been published on helminth parasites of A. piscivorus from other parts of its range, little (outside of its cestodes) is known about those other helminths occurring in cottonmouths of the state. In our survey, we examined seven adult A. piscivorus from Polk County and a single specimen from Calhoun County. Several helminth parasites were found, including three trematodes, Styphlodora magna, Renifer ellipticus, and Paralechriorchis syntomentera, two nematodes, an unknown larval ascarid and Physaloptera abjecta, an oligacanthorhynchid acanthocephalan cystacanth, and a …

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Hemoparasites (Apicomplexa: Hepatozoon; Kinetoplastida: Trypanosoma) Of Two Anurans (Hylidae; Ranidae), From Polk County, Arkansas, C.T. Mcallister, H.W. Robison Jan 2023

Hemoparasites (Apicomplexa: Hepatozoon; Kinetoplastida: Trypanosoma) Of Two Anurans (Hylidae; Ranidae), From Polk County, Arkansas, C.T. Mcallister, H.W. Robison

Journal of the Arkansas Academy of Science

Arkansas supports 26 species/subspecies of anurans and only one (4%), the green frog, Rana clamitans, has been previously reported with hemoparasites. Here, we collected blood samples from three species of anurans, five American green treefrogs, Dryophytes cinereus, five American bullfrogs, Rana catesbeianus, two southern leopard frogs, Rana sphenocephalus utricularius, and two Fowler’s toads, Anaxyrus fowleri from Polk County and examined each for hemoparasites. American green treefrogs and American bullfrogs harbored hemoparasites, including two (40%) D. cinereus and four (80%) R. catesbeianus with trypanosomes, and one (20%) R. catesbeiana with a Hepatozoon sp. This is the first time these two anurans …

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New Geographic Distributional Records For Two Lampreys (Petromyzontiformes: Petromyzontidae) In Arkansas, With Notes On Histopathology, C.T. Mcallister, H.W. Robison, E.M. Leis, D.G. Cloutman, A.C. Camus Jan 2023

New Geographic Distributional Records For Two Lampreys (Petromyzontiformes: Petromyzontidae) In Arkansas, With Notes On Histopathology, C.T. Mcallister, H.W. Robison, E.M. Leis, D.G. Cloutman, A.C. Camus

Journal of the Arkansas Academy of Science

The recent update (2nd edition) of the Fishes of Arkansas includes what is known, to date, on the geographic distribution of five species of lampreys that occur in the state. Here, we provide new distributional records on two of those species, the chestnut lamprey (Ichthyomyzon castaneus) and southern brook lamprey (I. gagei), as well as documenting host-parasite information (histopathology) caused by the former species.

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