Hubbard Model with Inter-Site Kinetic Correlations

We introduced the inter-site electron-electron correlation to the Hubbard III approximation. This correlation was excluded in the Hubbard III approximation and also in the equivalent coherent potential approximation. Including it brings two spin dependent effects: the bandwidth correction and the bandshift correction, which both stimulate the ferromagnetic ground state. The bandshift correction factor causes an exchange splitting between the spin-up and spin-down spectrum, and its role is similar to the exchange interaction in the classic Stoner model. The spin dependent bandwidth correction lowers the kinetic energy of electrons by decreasing the majority spin bandwidth for some electron occupations with respect to the minority spin bandwidth. In certain conditions it can lead to ferromagnetic alignment. A gain in the kinetic energy achieved in this way is the opposite extreme to the effect of a gain in potential energy due to exchange splitting. The bandshift factor is a dominant force behind the ferromagnetism. The influence of the bandwidth factor is too weak to create ferromagnetism and the only result is the correction to the classic coherent potential approximation in favor of ferromagnetism.Comment: 29 pages, 5 figure

Interleukin-4 inhibition of interleukin-1-induced expression of matrix metalloproteinase-3 (MMP-3) is independent of lipoxygenase and PPARγ activation in human gingival fibroblasts

BACKGROUND: Interleukin 4 (IL-4) has been shown to suppress interleukin-1 (IL-1) induced expression of matrix metalloproteinase-3 (MMP-3) in human synovial and gingival fibroblasts, but the mechanism of suppression has not been determined. Activators of peroxisome proliferator-activated receptor-γ (PPARγ) have been shown to inhibit cytokine induced expression of MMPs in other cell types, and IL-4 has been shown to activate PPARγ by stimulating production of ligands through the lipoxygenase pathway. It has been suggested that PPARγ may inhibit expression of MMPs by competing with transcription factor AP-1 for binding to a putative composite binding element in the promoters. The objective of this study was to determine whether the suppressive effects of IL-4 on the IL-1 induced expression of MMP-3 involve activation of lipoxygenase and/or PPARγ. RESULTS: Western blotting revealed the presence of PPARγ in nuclear extract of HGF. IL-1 induced binding of nuclear extract to the putative composite PPRE/AP-1 site was diminished in the presence of pioglitazone, but there was no evidence of any change in the composition of the retarded complexes, and no evidence of PPARγ binding to this site. Nordihydroguaiaretic acid (NDGA), a non-selective lipoxygenase inhibitor, and MK886, a specific inhibitor of 5-lipoxygenase, induced MMP-3 expression synergistically with IL-1. However IL-4 was still able to inhibit MMP-3 expression in the presence of NDGA or MK886 and IL-1. Activation of PPARγ with pioglitazone not only failed to inhibit IL-1 induced expression of MMP-3 mRNA, but rather super-induced MMP-3 in the presence of IL-1. PPARγ antagonist GW9662 failed to abolish the suppressive effects of IL-4. Another PPARγ activator, 15-deoxy-Delta12,14prostaglandin J2 (15dPGJ2), also super-induced MMP-3 mRNA, and this was due at least in part to increased transcription. CONCLUSION: IL-4 suppression of IL-1-induced MMP-3 expression in HGF is independent of lipoxygenase activity and activation of PPARγ. Super-induction of MMP-3 by pioglitazone may have important implications for patients using pioglitazone to treat type II diabetes in the presence of chronic inflammation

Adapting to Challenges Presented in Training New Students in Laboratory Techniques During COVID-19

Introduction: In early 2020, COVID-19 entered the United States, and by the end of March 2020, the city had mandated schools shut down to slow the spread and flatten the curve. Beginning in the fall, PCOM started slowly opening up research labs again to students with restrictions in capacity and returning onto campus. The new standards affected the normal timeline of introducing new students into the lab. The Bravo research laboratory takes an average of 20 students in each year, with a limited number of students allowed to be trained at the time, the lab management personnel had to adapt to be able to train them all. To counteract this, a plan to create virtual methods in preparing incoming students was started. The goal is to have students prepared to enter the lab in a safe manner while following all guidelines instructed by PCOM. Methods: Video footage was recorded following proper safety procedures set in place by PCOM. The filming process involved a two person team wearing N95 masks with one handling the experimental protocol while the second filmed using a digital video camera (model: HDV-604S). All video footage was transferred to a Macbook Pro and loaded into the software iMovie for video editing. The finished file was converted into a playable mp4 file and shared with the students using a GoogleDrive folder. Other softwares used for virtual communication included FaceTime and GoogleMeet to carry out virtual training and orientation. Results: The following procedures were created from the study: 1). Five minute video showing the Optical Coherence Tomography (OCT) experimental procedure. 2). Four minute video demonstrating the Electroretinography (ERT) procedure. 3). Three minute video documenting the process of obtaining eyes for histology. 4). Facetime is used to train students in changing oxygen tanks in the LAR for hyperoxia experiments. 5). GoogleMeet was used to present a powerpoint to provide the LAR orientation for incoming students. 6). Immunohistochemistry and Microscope training were conducted using GoogleMeet to present a powerpoint prior to a short in person demonstration to shorten exposure. Conclusions: The three videos served as a way for the incoming new students to become familiar with the various experimental protocols required in their project and allowed them to smooth transition onto campus. Students taking required courses prior to getting clearance will be able to start familiarizing themselves with required lab techniques. Returning students coming back into the lab will also be able to use these videos to refresh their techniques themselves prior to their day back in the lab. The powerpoints will provide students with proper lab safety/protocols as reference in the future. The plan is to use the media files as a reference for future students entering the lab when in-person training resumes as a standard in training. These virtual tools will provide flexibility for all future incoming students after restrictions are lifted

Period-Luminosity Relations for Galactic classical Cepheids in the Sloan bands

We present the first period-luminosity (PL) and period-Wesenheit (PW) relations in the Sloan-Pans-STARRS gP1rP1iP1 bands for classical fundamental mode Cepheids in the Milky Way. We used a relatively modest number of 76 stars for the PL and 84-85 stars for the PW relations calibration. The data for the project were collected with the network of 40-cm telescopes of Las Cumbres Observatory, and Gaia Data Release 3 parallaxes were used for the calculations. These gri-band PL and PW relations calibrations will be a useful tool for distance determinations in the era of large sky surveys using the Sloan photometric system, especially with the near-future start of the Large Synoptic Survey of Space and Time (LSST).Comment: 31 pages, 7 figures, 3 tables, Accepted for publication in Ap