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Search Results: 1 - 10 of 299833 matches for " Nathan J. Engbrecht "
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Mine Spoil Prairies Expand Critical Habitat for Endangered and Threatened Amphibian and Reptile Species
Michael J. Lannoo,Vanessa C. Kinney,Jennifer L. Heemeyer,Nathan J. Engbrecht,Alisa L. Gallant,Robert W. Klaver
Diversity , 2009, DOI: 10.3390/d1020118
Abstract: Coal extraction has been occurring in the Midwestern United States for over a century. Despite the pre-mining history of the landscape as woodlands, spent surface coalfields are often reclaimed to grasslands. We assessed amphibian and reptile species on a large tract of coal spoil prairie and found 13 species of amphibians (nine frog and four salamander species) and 19 species of reptiles (one lizard, five turtle, and 13 snake species). Two state-endangered and three state species of special concern were documented. The amphibian diversity at our study site was comparable to the diversity found at a large restored prairie situated 175 km north, within the historic prairie peninsula.
Solving the Unbalanced Assignment Problem: Simpler Is Better  [PDF]
Nathan Betts, Francis J. Vasko
American Journal of Operations Research (AJOR) , 2016, DOI: 10.4236/ajor.2016.64028
Abstract: Recently, Yadaiah and Haragopal published in the American Journal of Operations Research a new approach to solving the unbalanced assignment problem. They also provide a numerical example which they solve with their approach and get a cost of 1550 which they claim is optimum. This approach might be of interest; however, their approach does not guarantee the optimal solution. In this short paper, we will show that solving this same example from the Yadaiah and Haragopal paper by using a simple textbook formulation to balance the problem and then solve it with the classic Hungarian method of Kuhn yields the true optimal solution with a cost of 1520.
Ecology and Role of the Rove Beetle, Dalotia coriaria, and Insidious Flower Bug, Orius insidiosus, in Greenhouse Biological Control Programs  [PDF]
Raymond A. Cloyd, Nathan J. Herrick
Advances in Entomology (AE) , 2017, DOI: 10.4236/ae.2017.54012
Abstract: Greenhouse production systems typically involve growing multiple crop types simultaneously, including ornamentals and vegetables. Therefore, greenhouse producers commonly deal with multiple pest complexes. Two important insect pests of greenhouse-grown horticultural crops are fungus gnats (Bradysia spp.) and western flower thrips (Frankliniella occidentalis). A plant protection strategy that can be used to manage both pests is biological control. The rove beetle (Dalotia coriaria) and insidious flower bug (Orius insidiosus) are generalist predators commercially available for use in greenhouse production systems targeting fungus gnats and the western flower thrips. This article describes the biology, behavior, ecology, and role of both natural enemies in greenhouse production systems, and discusses the direct and indirect effects of pesticides (insecticides, miticides, and fungicides) on D. coriaria and O. inisidiosus.
Relevance of the stroma and epithelial-mesenchymal transition (EMT) for the rheumatic diseases
Nathan J Zvaifler
Arthritis Research & Therapy , 2006, DOI: 10.1186/ar1963
Abstract: Epithelial-mesenchymal transition (EMT) describes a process wherein static epithelial cells lose cell-cell contacts, acquire mesenchymal features and manifest a migratory phenotype. Multiple alternative terms, including epithelial-mesenchymal interactions, transformation, transdifferentation, and transition, have been used interchangeably to describe this process. I've chosen 'transition' for the reasons elaborated by Kalluri and Neilson [1], whose excellent publication is recommended to any reader interested in the entire subject. EMT, which was first appreciated by developmental biologists in the 1980s, is now attracting the attention of investigators interested in metastatic cancers and diseases characterized by fibrosis [1,2]. This review will explain these observations briefly and consider how they might be relevant to certain rheumatic diseases.In the embryo the first and only tissue formed is epithelium [3]. Sheets of epithelial cells are held together tightly at strong adherens junctions containing E-cadherin in complexes with catenins linked to the actin cytoskeleton. The epithelial cells are firmly attached through integrins to an underlying extracellular matrix (ECM) containing type IV collagen and laminin; the basement membrane. Around day 15 the epiblast cells of the developing human embryo migrate into a structure called the primitive streak [4]. Once in place they assume the features of embryonic mesoderm and endoderm in a process known as gastrulation. From the mesoderm arise the visceral and limb bud mesenchyme. The latter is the source of bone, cartilage, fibroblasts, fat, skeletal muscle and the bone marrow stroma.Although mesenchymal cells are secretory and produce collagens, fibronectin, vimentin, and alpha smooth muscle actin (α SMA), no one of these is unique to this cell type. The attribute that sets mesenchymal cells apart is their ability to invade and move through the three-dimensional structure of the ECM. Accordingly, mesenchymal cells a
Electronic Commerce Adoption in the Arab Countries – An Empirical Study
Robert J. Nathan
International Arab Journal of e-Technology , 2009,
Abstract: This study examines the factors that affect Electronic Commerce (EC) adoption in the Arab countries. The five countries that are represented in this study include Saudi Arabia, Qatar, Kuwait, United Arab Emirates and Yemen. The purpose of this study is analyzing the crucial factors affecting EC adoption among the Arab consumers. The study examines the effect of risk perception, trust and consumer knowledge on their EC adoption. It also highlights consumer’s knowledge mediation in affecting their perception of risk and trust towards EC adoption. Upon filtration, three hundred samples were selected for data analysis in this study. Descriptive and inferential statistical analyses including statistical mediation technique were carried out to analyse the data. Results reveal knowledge as the most important factor that contributes to EC adoption and it mediates consumers’ perception of risk and trust in contributing to their EC adoption. The preliminary finding of this study was presented in the International Arab Conference of E-Technology held in Amman, Jordan from 14th to 16th October 2008. This paper presents the complete study and further data analysis with extended report and discussions.
The dialectics of vision: Oskar Kokoschka and the historiography of expressionistic sight
Nathan J. Timpano
Journal of Art Historiography , 2011,
Abstract: In his seminal essay ‘On the Nature of Visions’, Oskar Kokoschka proposes a theory of expressionistic sight that advocates the centrality of both optical and psychological processes in the development of this sensorial construct. The present study argues that Kokoschka’s novel handling of the role of vision in the image forming process implicitly elucidates expressionistic sight as a process fashioned through the dialectical tension that arises from these two prevalent, though oppositional views of artistic vision in the early twentieth century. As such, the historiography of expressionistic sight offered by Kokoschka stands in stark contrast to other prevailing histories written by his interlocutors in fin-de-siècle Germany and Austria.
Effective Homology of the Pushout of Simplicial Sets
Jónathan Heras
Mathematics , 2014,
Abstract: In this paper, an algorithm building the effective homology version of the pushout of the simplicial morphisms $f:X\rightarrow Y$ and $g:X\rightarrow Z$, where $X,Y$ and $Z$ are simplicial sets with effective homology is presented.
The Effect of Fasting on PET Imaging of Hepatocellular Carcinoma  [PDF]
Nathan Tenley, David J. Corn, Lewis Yuan, Zhenghong Lee
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.42071

The clinical utility of positron emission tomography (PET) imaging for liver cancer applications is not clearly defined either for diagnosis or treatment assessment. Previous clinical studies demonstrated that fluorodeoxyglucose (FDG) did not show uptake in some hepatocellular carcinoma (HCC) while acetate showed uptake. Pre-imaging fasting is required for clinical PET imaging with FDG. No studies were done to confirm the effect of fasting on acetate uptake in HCC for PET imaging. We investigated this situation with a woodchuck model of viral infection-induced HCC. Methods: Four tumor-bearing and one control woodchucks were involved in this study. They were first imaged by PET in fed state followed by another imaging session one week later when they were fasted over-night. Some animals also had FDG- PET scan that was acquired later on the same day. After imaging studies, animals were sacrificed, and their liver excised for histology. Standardized Uptake Value (SUV) was calculated using a region of interest (ROI) placed on each tumor with focal uptake. Results: Acetate showed uptake in each HCC lesion when the animals were either fasted or fed with no significant difference in SUV values (p = 0.177); some of the tumors were histologically confirmed as well-differentiated HCC while others were confirmed as moderately- or poorly-differentiated HCC; no focal uptake was found in the control animal. For the accompanying FDG scans, the uptake was detected only in animals that were fasted although the uptake pattern was different from that with acetate. Conclusion: This study provided a hint that fasting or not has little impact on PET imaging of HCC with acetate. It also confirmed prior finding regarding tumor heterogeneity that led to different tracer uptake pattern in the same tumor. Human studies are needed to validate the findings from this pre-clinical investigation.

Simplified ART Delivery Models Are Needed for the Next Phase of Scale Up
Nathan Ford ,Edward J. Mills
PLOS Medicine , 2011, DOI: 10.1371/journal.pmed.1001060
Mechanobiology of Platelets: Techniques to Study the Role of Fluid Flow and Platelet Retraction Forces at the Micro- and Nano-Scale
Shirin Feghhi,Nathan J. Sniadecki
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12129009
Abstract: Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation.
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