Effect of the stellar spin history on the tidal evolution of close-in planets

We investigate how the evolution of the stellar spin rate affects, and is affected by, planets in close orbits, via star-planet tidal interactions. To do this, we used a standard equilibrium tidal model to compute the orbital evolution of single planets orbiting both Sun-like stars and 0.1 M\odot M-dwarfs. We tested two stellar spin evolution profiles, one with fast initial rotation (P=1.2 day) and one with slow initial rotation (P=8 day). We tested the effect of varying the stellar and planetary dissipation and the planet's mass and initial orbital radius. Conclusions: Tidal evolution allows to differentiate the early behaviors of extremely close-in planets orbiting either a rapidly rotating star or a slowly rotating star. The early spin-up of the star allows the close-in planets around fast rotators to survive the early evolution. For planets around M-dwarfs, surviving the early evolution means surviving on Gyr timescales whereas for Sun-like stars the spin-down brings about late mergers of Jupiter planets. In light of this study, we can say that differentiating between one spin evolution from another given the present position of planets can be very tricky. Unless we can observe some markers of former evolution it is nearly impossible to distinguish the two very different spin profiles, let alone intermediate spin profiles. Though some conclusions can still be drawn from statistical distributions of planets around fully convective M-dwarfs. However, if the tidal evolution brings about a merger late in its history it can also entail a noticeable acceleration of the star in late ages, so that it is possible to have old stars that spin rapidly. This raises the question of better constraining the age of stars

The Lantern Vol. 63, No. 2, Spring 1996

• Poet, Lead Me On • St. Patrick\u27s Day • The Last Three Days • The Impressionable • Roundabout • The Bench • Carnivorous • Kyrie • Second Glance • Porch • Cruel Design • A Mime • Flaxen Crown • My Embryonic Ocean of Love • Stone Matrix • Voices from the Past • Skipping the Bullfight: Toreadors and Gaudi • Another Part of My Lacolonialism • Translucent Pane • Linguistics • Treehouse • A Disagreeable Music Piece • Vigil • A Brief History of American Poetry in Englishhttps://digitalcommons.ursinus.edu/lantern/1148/thumbnail.jp

2016 Research & Innovation Day Program

A one day showcase of applied research, social innovation, scholarship projects and activities.https://first.fanshawec.ca/cri_cripublications/1003/thumbnail.jp

Overview of CENS Statistics and Data Practices Research

Data, statistical models and inferential procedures permeate CENS deployments, from the four founding scientific application areas to the more recent urban sensing campaigns. This cross-center research breaks down into three classes of research: 1) General statistical models for embedded sensing, with specific applications to data quality and continuous sampling, 2) Significant CENS-designed and supported databases and repositories, and 3) Studies into the data lifecycle for embedded sensing systems

Estrogen receptors alpha and beta in rat placenta: detection by RT-PCR, real time PCR and Western blotting

<p>Abstract</p> <p>Background</p> <p>High levels of estrogens during pregnancy not only retard placental and fetal growth but can lead to reproductive tract abnormalities in male progeny. Estrogens act through estrogen receptors (ER) to modulate the transcription of target genes. These ER exist in two isoforms, ER alpha and ER beta and recently several variants of these isoforms have been identified.</p> <p>Methods</p> <p>The expressions of ER isoforms and variants have been studied in rat placenta at 16, 19 and 21 days gestation (dg). Gene expression was assessed using RT-PCR and real time PCR while protein expression was studied using Western blotting followed by immunodetection. Placental homogenates were probed with: a monoclonal antibody raised against the steroid binding domain of the ER alpha (ER alpha -S), a monoclonal antibody raised against the hinge region of ER alpha (ER alpha -H) and a polyclonal antibody raised against the amino terminus of ER beta.</p> <p>Results</p> <p>ER alpha and ER beta mRNA and protein were detected from as early as 16 dg. Two PCR products were detected for ER alpha, one for the wild type ER alpha, and a smaller variant. Real time PCR results suggested the presence of a single product for ER beta. The antibodies used for detection of ER alpha protein both identified a single 67 kDa isoform; however a second 54 kDa band, which may be an ER alpha variant, was identified when using the ER alpha -H antibody. The abundance of both ER alpha bands decreased significantly between 16 and 19 dg. As for ER beta, four bands (76, 59, 54 and 41 kDa) were detected. The abundance of the 59 and 54 kDa bands decreased significantly between 16 and 19 dg.</p> <p>Conclusion</p> <p>This study shows that both ER protein isoforms and their variants are present in rat placenta. The decrease in their expression near parturition suggests that the placenta may be relatively unresponsive to estrogens at this stage.</p