General Relativistic Simulations of Magnetized Plasmas around Merging Supermassive Black Holes

Coalescing supermassive black hole binaries are produced by the mergers of galaxies and are the most powerful sources of gravitational waves accessible to space-based gravitational observatories. Some such mergers may occur in the presence of matter and magnetic fields and hence generate an electromagnetic counterpart. In this Letter, we present the first general relativistic simulations of magnetized plasma around merging supermassive black holes using the general relativistic magnetohydrodynamic code Whisky. By considering different magnetic field strengths, going from non-magnetically dominated to magnetically dominated regimes, we explore how magnetic fields affect the dynamics of the plasma and the possible emission of electromagnetic signals. In particular we observe a total amplification of the magnetic field of ~2 orders of magnitude which is driven by the accretion onto the binary and that leads to much stronger electromagnetic signals, more than a factor of 10^4 larger than comparable calculations done in the force-free regime where such amplifications are not possible.Comment: 7 pages, 5 figures. Minor changes to match version accepted for publication on The Astrophysical Journal Letter

COVID-19 and chronological aging : senolytics and other anti-aging drugs for the treatment or prevention of corona virus infection?

COVID-19, also known as SARS-CoV-2, is a new emerging zoonotic corona virus of the SARS (Severe Acute Respiratory Syndrome) and the MERS (Middle East Respiratory Syndrome) family. COVID-19 originated in China and spread world-wide, resulting in the pandemic of 2020. For some reason, COVID-19 shows a considerably higher mortality rate in patients with advanced chronological age. This begs the question as to whether there is a functional association between COVID-19 infection and the process of chronological aging. Two host receptors have been proposed for COVID-19. One is CD26 and the other is ACE-2 (angiotensin-converting enzyme 2). Interestingly, both CD26 and the angiotensin system show associations with senescence. Similarly, two proposed therapeutics for the treatment of COVID-19 infection are Azithromycin and Quercetin, both drugs with significant senolytic activity. Also, Chloroquine-related compounds inhibit the induction of the well-known senescence marker, Beta-galactosidase. Other anti-aging drugs should also be considered, such as Rapamycin and Doxycycline, as they behave as inhibitors of protein synthesis, blocking both SASP and viral replication. Therefore, we wish to speculate that the fight against COVID-19 disease should involve testing the hypothesis that senolytics and other anti-aging drugs may have a prominent role in preventing the transmission of the virus, as well as aid in its treatment. Thus, we propose that new clinical trials may be warranted, as several senolytic and anti-aging therapeutics are existing FDA-approved drugs, with excellent safety profiles, and would be readily available for drug repurposing efforts. As Azithromycin and Doxycycline are both commonly used antibiotics that inhibit viral replication and IL-6 production, we may want to consider this general class of antibiotics that functionally inhibits cellular protein synthesis as a side-effect, for the treatment and prevention of COVID-19 disease

Professional sports teams & the community: a comparative case study of two professional basketball teams

All organizations are unique in their individual goals and aspirations. However, often is the case that organizations within the same industry share perspectives and overarching themes regarding how they go about achieving their perspective goals. In my paper, I will be comparing two professional basketball organizations that from first glance have very little, if anything, in similar besides the fact that they are both professional basketball teams. Through my research and personal experiences, I aim to answer the question of whether or not two professional basketball organizations are more alike in their community engagement and involvement than we would assume based upon their differences in size, financials, and locations. I hope to show that while different in so many ways, the end goal of building a brand through community outreach is possible regardless of whether it is with a small town basketball organization in Germany or one of the biggest sports franchises in one of the biggest cities in the world

Study of pickup of cometary ions in turbulent solar winds

The influence of moderately strong magnetic disturbances on the ion pickup process near a comet is studied by a test-particle method. The research is motivated by recent observations with ICE and Giotto at Giacobini-Zinner and Halley. In this numerical study, the intrinsic hydromagnetic turbulence is modelled based on the Giotto and ICE data. The time evolution of the distribution function of the newborn ions is investigated. It is found that, when the level of the intrinsic turbulence is sufficiently high, the pickup ions can form a shell distribution function rapidly. The typical time scale for such a process is of the order of a couple of ion gyroperiods. On the other hand, if the turbulence is not strong, the pickup ions usually form an incomplete shell in the initial stage. The results seem to be consistent with available observations

"A Program of Opera Scenes," November 8, 9, 1985

This is the concert program of the "A Program of Opera Scenes" performance on Friday, November 8, and Saturday, November 9, 1985, at the Concert Hall, 855 Commonwealth Avenue. Scenes performed were Act II, scene 2 from The Merry Wives of Windsor by Otto Nicolai, Act II, scenes 1 and 2 from Hansel and Gretel by Engelbert Humperdinck, Act I Duet from L'Elisir D'Amore by Gaetano Donizetti, Act II, scene 2 from The Rake's Progress by Igor Stravinsky, with libretto by W. H. Auden and Chester Kallman, Act II Quintet from Carmen by Georges Bizet, with libretto by H. Meilhac and L. Halevy, Act III from La Bohème by Giacomo Puccini, with libretto by G. Giacosa and L. Illica, and Act I finale from Così fan tutte by Wolfgang Amadeus Mozart, with libretto by Lorenzo Da Ponte. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund

A cross-context look at upper-division student difficulties with integration

We investigate upper-division student difficulties with direct integration in multiple contexts involving the calculation of a potential from a continuous distribution (e.g., mass, charge, or current). Integration is a tool that has been historically studied at several different points in the curriculum including introductory and upper-division levels. We build off of these prior studies and contribute additional data around student difficulties with multi-variable integration at two new points in the curriculum: middle-division classical mechanics, and upper-division magnetostatics. To facilitate comparisons across prior studies as well as the current work, we utilize an analytical framework that focuses on how students activate, construct, execute, and reflect on mathematical tools during physics problem solving (i.e., the ACER framework). Using a mixed-methods approach involving coded exam solutions and student problem-solving interviews, we identify and compare students' difficulties in these two different context and relate them to what has been found previously in other levels and contexts. We find that some of the observed student difficulties were persistent accross all three contexts (e.g., identifying integration as the appropriate tool, and expressing the difference vector), while other difficulties seemed to fade as students advanced through the curriculum (e.g., expressing differential line, area, and volume elements). We also identified new difficulties that appear in different contexts (e.g., interpreting and expressing the current density).Comment: 13 pages, 2 figures, submitted to Phys. Rev. PE

Designing Online Activities for Teaching Quantum Mechanics: A Research-Based Approach

We present a research basis for the development of ACE Physics&mdash;a new website that hosts online tutorials (i.e., interactive worksheets) for teaching quantum mechanics. Unlike most physics tutorials, we have designed ours for completion outside the classroom and without instructor facilitation. This makes them easier for instructors to adopt, but introduces various tradeoffs and challenges, which we explore. These challenges underscore the importance of research as a tool for informing the design and goals of our activities as well as for evaluating their effectiveness. Our tutorials aim to help students develop intuition, so we begin with a study of student perspectives on intuition in quantum mechanics, which can inform instructional choices as well as future physics education research into the elusive but essential role of intuition in physics. We find that students have varied views on intuition and identify several ways that it can be integrated into instruction. We then report an investigation into student understanding of basis and change of basis&mdash;key ideas in any quantum course&mdash;which informed the creation of a tutorial about these topics. Next, we examine student behaviors during in-class tutorials. We present a framework for analyzing video data from this context, report findings from applying the framework, and explore how these findings can guide modifications to tutorials for use outside class. Finally, we evaluate the success of ACE Physics tutorials assigned as homework using two methods. First, we report content learning gains associated with two different tutorials as measured by pre- and post-testing. Second, we investigate student engagement with and feedback about ACE Physics using various survey data as well as interaction data collected by the website. We find mixed but largely positive results, suggesting that we should continue developing these activities and conduct further studies of their effectiveness. We conclude with an overview of the strategies we have developed for designing online physics tutorials, which synthesizes our findings as they apply to curriculum development.</p

Magnetically-induced outflows from binary neutron star merger remnants

Recent observations by the Swift satellite have revealed long-lasting ($\sim 10^2-10^5\,\mathrm{s}$), "plateau-like" X-ray afterglows in the vast majority of short gamma-ray bursts events. This has put forward the idea of a long-lived millisecond magnetar central engine being generated in a binary neutron star (BNS) merger and being responsible for the sustained energy injection over these timescales ("magnetar model"). We elaborate here on recent simulations that investigate the early evolution of such a merger remnant in general-relativistic magnetohydrodynamics. These simulations reveal very different conditions than those usually assumed for dipole spin-down emission in the magnetar model. In particular, the surrounding of the newly formed NS is polluted by baryons due to a dense, highly magnetized and isotropic wind from the stellar surface that is induced by magnetic field amplification in the interior of the star. The timescales and luminosities of this wind are compatible with early X-ray afterglows, such as the "extended emission". These isotropic winds are a generic feature of BNS merger remnants and thus represent an attractive alternative to current models of early X-ray afterglows. Further implications to BNS mergers and short gamma-ray bursts are discussed.Comment: 4 pages, 2 figures. To appear in proceedings of "Swift: 10 Years of Discovery