Bulletin of the American Physical Society
2020 Fall Meeting of the APS Prairie Section
Volume 65, Number 22
Friday–Sunday, November 13–15, 2020; Virtual
Session C07: Parallel F |
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Chair: Jeff Wereszczyski, Illinois Institute of Technology |
Sunday, November 15, 2020 3:00PM - 3:15PM |
C07.00001: Stochastic lattice simulation of competing nucleoproteins binding to single-stranded DNA S.M. Ali Tabei Homologous recombination (HR) is one of the most enigmatic processes in DNA metabolism and is a fundamental driver of evolution. Its central step involves the search for homology between two DNA molecules and the subsequent exchange of the DNA strands. We developed a dynamic Monte Carlo model to study the competition and dynamics of nucleoproteins binding/unbinding to single stranded DNA. In addition, we have developed a computational toolbox to identify and categorize different kinetic scenarios from single-molecule data. [Preview Abstract] |
Sunday, November 15, 2020 3:15PM - 3:30PM |
C07.00002: Mathematical Models for Living Forms in Medical Physics Submodel 1: The Information Processing from Teeth to Nerves Christina Pospisil This talk continues the presentation at APS March Meeting 2019 and APS April Meeting 2019. In this part of the project the first submodel is presented. The information processing from teeth to the nerves. Information processing is modeled via p-waves passing through the tooth layers enamel and dentin. Odontoblasts located in the liquid in the tubules of the tooth dentin layer perform finally the transformation into electrical information (an electrical signal) that passes along nerves. The presentation was scheduled for the APS March Meeting 2020 Conference (the APS March Meeting 2020 Conference got canceled because of Covid-19), the presentation was given at the APS April Meeting 2020 Conference. [Preview Abstract] |
Sunday, November 15, 2020 3:30PM - 3:45PM |
C07.00003: Visualization and Simulation of Traffic Flow Michael Nsor, Kishor Kapale We are interested in simulating and visualizing different scenarios that cause traffic jams and develop strategies to avoid them for the benefit of traffic engineers and policy makers. We use a software suite called NetLogo for this purpose. NetLogo provides a powerful platform for studying, interpreting, visualizing, and replicating complex systems not only in Physics but also in other fields by using agent-based models. This project focuses on analyzing traffic systems by changing parameters such as number of cars in the traffic lane, acceleration and deceleration of cars chosen based on the surroundings. We link NetLogo with Mathematica for data visualization and automated control of the software over a large parameter range in order to study the effect of these parameters in the traffic system. This will help to better understand traffic management strategies. We will also look at how this study can influence features that may be useful to have in driverless cars. [Preview Abstract] |
Sunday, November 15, 2020 3:45PM - 4:00PM |
C07.00004: Primordial black holes and second order gravitational waves from inflationary $\alpha$-attractor models Rafid Mahbub I will talk about primordial black hole (PBH) formation using a type of inflection-point potential derived using the inflationary $\alpha$-attractor model. The inflection plateau region gives rise to a phase called ultra slow-roll (USR) where the curvature power spectrum $\mathcal{P}_{\zeta}$ is amplified upto $10^{-3}$ and $10^{-2}$ which produces the right conditions for PBH formation. The curvature perturbation modes that collapse to form PBHs are approximately $k\sim 10^{14}\text{Mpc}^{-1}$, giving rise to PBHs in the mass range $10^{16}$ to $10^{18}\text{g}$ which can be cosmologically relevant as a cold dark matter (CDM) candidate. The abundance of PBHs is derived using a modification of the Press-Schechter theory which takes into account the intrinsic non-Gaussianity of the overdensity perturbations $\delta\rho/\rho$. I will present the results with the nonvanishing skewness and kurtosis of the distribution of $\delta\rho/\rho$ and show that this $\alpha$-attractor inflationary model can produce PBHs that can comprise a cosmologically significant proportion of CDM. We will also see that second order gravitational waves can be produced from this model in the frequency range $10^{-2}$ to $10^{2}\text{Hz}$ at levels which can potentially be detected in the future. [Preview Abstract] |
Sunday, November 15, 2020 4:00PM - 4:15PM |
C07.00005: A disk-dominated and clumpy circumgalactic medium of the Milky Way seen in X-ray emission using a CubeSat Philip Kaaret The Milky Way galaxy is surrounded by a circumgalactic medium (CGM) that may play a key role in galaxy evolution. The CGM has an ionized component at temperatures near 2 million Kelvin studied primarily in the soft X-ray band. Here we report a survey of the southern Galactic sky with a soft X-ray spectrometer on a CubeSat optimized to study diffuse soft X-ray emission. The X-ray emission is best fit with a disk-like model based on the radial profile of the surface density of molecular hydrogen, a tracer of star formation. This suggests that the X-ray emission is predominantly from hot plasma produced via stellar feedback. Strong variations in the X-ray emission on angular scales of about 10-20 degrees indicate that the CGM is clumpy which is also consistent with stellar feedback. Addition of an extended, and possibly massive, halo component is needed to match the halo density inferred from other observations. [Preview Abstract] |
Sunday, November 15, 2020 4:15PM - 4:30PM |
C07.00006: The rare, galaxy cluster environment of the short GRB161104A and a comparison to the short GRB host population Anya Nugent Short gamma ray bursts (SGRBs; $z\sim$ 0.1-2) provide unique cosmological analogs to local binary neutron star mergers detected by gravitational wave facilities. In particular, their host galaxies allow us to uniquely constrain the progenitor systems based on their parent stellar population properties. Here, I discuss one rare instance of an SGRB (161104A) uncovered in a faint galaxy cluster at $z \approx 0.8$. I fit deep optical and near-infrared observations of its host with state-of-the-art galaxy models to determine its stellar population properties, such as mass, age, metallicity, dust extinction, and star formation rate. I compare these results to the stellar population properties of 20 more SGRB hosts, three of which are also in galaxy clusters, and also place accurate constraints on the masses and ages of this sample. Lastly, I determine a lower limit on the fraction of SGRBs in clusters: $\approx 5-13\%$, and compare several observational properties of the SGRBs associated with clusters, finding that they are more offset and have fainter afterglows than the rest of the population, thus potentially linking them to unique progenitor dynamics affected by the cluster environment. [Preview Abstract] |
Sunday, November 15, 2020 4:30PM - 4:45PM |
C07.00007: Projective Origins of the Inflaton Kenneth Heitritter We detail how the recently developed projectively-invariant gravitational model, Thomas-Whitehead Gravity (TW Gravity), naturally gives rise to a field acting as the inflaton. In the formulation of TW Gravity, a field $\mathcal{D}_{ab}$ is introduced into the components of a projective connection. This field, $\mathcal{D}_{ab}$, is related to a rank-two tensor field $\mathcal{P}_{ab}$. Through the action of TW Gravity, in terms of projective curvature invariants, the tensor field $\mathcal{P}_{ab}$ acquires dynamics. Decomposing $\mathcal{P}_{ab}$ into its trace and traceless degrees of freedom, we show that the action can describe a type of non-minimally coupled inflaton action. We calculate values for the spectral index $n_s$, tensor-to-scalar ratio $r$, and scalar amplitude $A_s$. These calculated quantities are shown to lie within bounds from the most recent Planck analysis, for a discrete range of free parameters. [Preview Abstract] |
Sunday, November 15, 2020 4:45PM - 5:00PM |
C07.00008: Do Gamma-ray Bursts Produce Magnetars? Genevieve Schroeder Short gamma-ray bursts (SGRBs), which are thought to come from the mergers of binary neutron stars (BNS), may produce massive, rapidly spinning, highly magnetized neutron stars, known as magnetars. These magnetars may deposit a fraction of their rotational energy into the surrounding kilonova ejecta, powering a synchrotron radio signal from the interaction of the ejecta with the circumburst medium. Combining new radio observations with previous studies, we uniformly analyzed 27 low-redshift($z<0.5$) SGRBs and found that $\gtrsim 50\%$ of SGRBs did not form stable magnetar remnants in their mergers. Assuming SGRBs are produced by BNS mergers drawn from the Galactic BNS population plus an additional component of high-mass mergers, we place constraints on the maximum mass of a non-rotating neutron star to be $\lesssim 2.23\,M_{\odot}$. Our methods are complementary to studies in pulsars and gravitational waves which explore the masses that can be achieved for neutron stars. [Preview Abstract] |
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