Examining the Impact of Cooperatives and Spatial Expansion on Agriculture-based Growth

The prosperous nations of today have a history of economic growth based on flourishing agricultural activity. This project aims to investigate causes of agricultural-based growth in the United States of America and Canada by drawing a comparison to Denmark. We compare the Danish dairy model with the dairy and wheat agriculture in the U.S. and Canada. We focus on Senghaas’ theory of social capital development by cooperative organization and Harvey’s theory of spatial fix by geographic expansion as possible explanations for agricultural productivity growth in the U.S., Canada, and Denmark. A qualitative analysis of agricultural histories provides weak evidence for successful cooperative movement in the U.S. and Canada as compared to the successful Danish model. The productivity comparison among the nations provides conclusive evidence for highest productivity in favor of the successful Scandinavian case while demonstrating productivity growth in all cases. However, historical agricultural production statistics do show evidence of massive volume of production in other cases despite low productivity. We further expand our analysis to understand the differences in Danish and North American experience based on the existence of frontier in the latter case. The results of correlation between productivity growth and input expansion also fail to explain the observed difference in productivity growth amongst the three cases. Thus, we conclude that neither cooperative organization nor availability of widespread arable land were causes of increasing agricultural productivity in the U.S. and Canada. Their impressive agricultural growth can likely be attributed to their massive scale of production made possible due to widespread arable land

Dynamic 3D Cell Rearrangements Guided by a Fibronectin Matrix Underlie Somitogenesis

Somites are transient segments formed in a rostro-caudal progression during vertebrate development. In chick embryos, segmentation of a new pair of somites occurs every 90 minutes and involves a mesenchyme-to-epithelium transition of cells from the presomitic mesoderm. Little is known about the cellular rearrangements involved, and, although it is known that the fibronectin extracellular matrix is required, its actual role remains elusive. Using 3D and 4D imaging of somite formation we discovered that somitogenesis consists of a complex choreography of individual cell movements. Epithelialization starts medially with the formation of a transient epithelium of cuboidal cells, followed by cell elongation and reorganization into a pseudostratified epithelium of spindle-shaped epitheloid cells. Mesenchymal cells are then recruited to this medial epithelium through accretion, a phenomenon that spreads to all sides, except the lateral side of the forming somite, which epithelializes by cell elongation and intercalation. Surprisingly, an important contribution to the somite epithelium also comes from the continuous egression of mesenchymal cells from the core into the epithelium via its apical side. Inhibition of fibronectin matrix assembly first slows down the rate, and then halts somite formation, without affecting pseudopodial activity or cell body movements. Rather, cell elongation, centripetal alignment, N-cadherin polarization and egression are impaired, showing that the fibronectin matrix plays a role in polarizing and guiding the exploratory behavior of somitic cells. To our knowledge, this is the first 4D in vivo recording of a full mesenchyme-to-epithelium transition. This approach brought new insights into this event and highlighted the importance of the extracellular matrix as a guiding cue during morphogenesis

Synchronization in network motifs of delay-coupled map-based neurons

Synchronization in network motifs of delay-coupled map-based neuron

Synchronization in network motifs of delay-coupled map-based neurons

We study the influence of delayed coupling on synchronization in neural network motifs. Numerical simulations based on the Rulkov map reveal different behavior in the presence and in the absence of the delay. While without delay, synchronization improves as the coupling strength is increased, in the presence of a delay, synchronization becomes worse. We also study how a feedback loop affects synchronization. An increase in the number of neurons involved in the loop leads to desynchronization in the motifs, saturating at a certain value of the synchronization index

A Kinetic Study of Silver Electrodeposition Onto Pt Ultramicroelectrodes From Amoniacal Solutions

A kinetic study of the Ag electrodeposition onto Pt ultramicroelectrodes of 10, 15 and 25 µm of diameter from an aqueous solution containing AgNO3 1 mM + NH4NO3 0.1 M was conducted at overpotential conditions through potentiostatic studies. The analysis of the current density transients indicates the existence of two 2D nucleation and growth processes previous to the 3D nucleation and growth process. This work is licensed under a Creative Commons Attribution 4.0 International License

Development of Bexarotene Analogs for Treating Cutaneous T-Cell Lymphomas

Bexarotene, a drug approved for treatment of cutaneous T-cell lymphoma (CTCL), is classified as a rexinoid by its ability to act as a retinoid X receptor (RXR) agonist with high specificity. Rexinoids are capable of inducing RXR homodimerization leading to the induction of apoptosis and inhibition of proliferation in human cancers. Numerous studies have shown that bexarotene is effective in reducing viability and proliferation in CTCL cell lines. However, many treated patients present with cutaneous toxicity, hypothyroidism, and hyperlipidemia due to crossover activity with retinoic acid receptor (RAR), thyroid hormone receptor (TR), and liver X receptor (LXR) signaling, respectively. In this study, 10 novel analogs and three standard compounds were evaluated side-by-side with bexarotene for their ability to drive RXR homodimerization and subsequent binding to the RXR response element (RXRE). In addition, these analogs were assessed for proliferation inhibition of CTCL cells, cytotoxicity, and mutagenicity. Furthermore, the most effective analogs were analyzed via qPCR to determine efficacy in modulating expression of two critical tumor suppressor genes, ATF3 and EGR3. Our results suggest that these new compounds may possess similar or enhanced therapeutic potential since they display enhanced RXR activation with equivalent or greater reduction in CTCL cell proliferation, as well as the ability to induce ATF3 and EGR3. This work broadens our understanding of RXR–ligand relationships and permits development of possibly more efficacious pharmaceutical drugs. Modifications of RXR agonists can yield agents with enhanced biological selectivity and potency when compared to the parent compound, potentially leading to improved patient outcomes. © 2023 by the authors.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]