Fitting the radial acceleration relation to individual SPARC galaxies

Galaxies follow a tight radial acceleration relation (RAR): the acceleration observed at every radius correlates with that expected from the distribution of baryons. We use the Markov Chain Monte Carlo method to fit the mean RAR to 175 individual galaxies in the SPARC database, marginalizing over stellar mass-to-light ratio ($\Upsilon_{\star}$), galaxy distance, and disk inclination. Acceptable fits with astrophysically reasonable parameters are found for the vast majority of galaxies. The residuals around these fits have an rms scatter of only 0.057 dex ($\sim$13$\%$). This is in agreement with the predictions of modified Newtonian dynamics (MOND). We further consider a generalized version of the RAR that, unlike MOND, permits galaxy-to-galaxy variation in the critical acceleration scale. The fits are not improved with this additional freedom: there is no credible indication of variation in the critical acceleration scale. The data are consistent with the action of a single effective force law. The apparent universality of the acceleration scale and the small residual scatter are key to understanding galaxies.Comment: 12 pages, 7 figures, 2 tables. Accepted for publication in A&A. The same as the first version with typos corrected. A set of 175 figures is available at http://astroweb.cwru.edu/SPARC

Extinction of fear in the amygdala: Justification and development of a neuron model [abstract]

Abstract only availableFaculty Mentor: Dr. Satish Nair, Electrical EngineeringAnxiety disorders cause chronic reactions to a triggering event that disrupt pursuit of normal daily routines. Disorders such as post-traumatic stress disorder or specific phobia can be ameliorated through the process of fear extinction. By examining the studies published on fear extinction as well as ones on mechanisms of long-term depression (LTD) of neurons in rats, specific receptors and chemical messengers that inhibit easily excited neuronal fear connections have been found and used to provide justification and modification of a computational model of this extinction learning in the rat amygdala (where the mediation of fear memory is thought to occur). These mechanisms of fear inhibition can work by affecting both the presynaptic neuron and the neuron on which it acts (postsynaptic neuron). For example, depotentiation at lateral amygdala synapses did not depend on adenosine A1 or metabotropic glutamate receptor II (mGlurRII), but did require NMDA receptors, L-type voltage gated calcium channels (LVGCCs), and calcineurin; when calcium enters through NMDA receptors and LVGCCs to activate calcineurin, the calcineurin reduces the excitability of the neuron through inactivation of postsynaptic neurotransmitter receptors. Also, long-term depression of presynaptic release of neurotransmitters was found to be mediated by postsynaptic retrograde diffusion of nitric oxide back across the synapse. Although parameters that affect the acquisition and extinction of fear memories have yet to be well understood or quantified, the computational model using GENESIS (GEneral NEural SImulation System) incorporates the most up-to-date findings of neuronal studies. The program simulates the response of a pyramidal neuron in the lateral amygdala to sensitization, conditioning, and extinction of a tone and shock-induced fear. Through matching of experimental data, the model may help predict what cellular mechanisms should be further investigated in order to ultimately develop a way to better treat anxiety disorders

Responding to Sustainability with Sentimental Messages Disseminated through Social Media

Fast fashion brands seem to communicate their CSR activities via social media platforms, the effect of which can be explained through the attribution theory. Depending on whether the information received is negative or positive, this study aims to explore how consumers view and respond to fashion brands’ sustainability-related messages posted on social media. Data was collected by a survey company in the spring of 2018, and a total of 258 complete responses were used for data analysis. These findings suggest that when environmentally-conscious consumers evaluate communication through social media, they respond to both the perceived intrinsic and extrinsic motives of sustainability messages. Finally, this study recommends additional research on how to improve message content to make it more memorable, and therefore shared by the core consumers of fashion brands, to help improve all fashion brands’ overall communication efforts

Luxury shopping tourism : views from Chinese post-1990s female tourists

Peer reviewedPostprin

Carceral Carousel

The prison industrial complex is a highly adaptive mechanism that is constantly shifting to sustain itself. In recent years, the movement against mass incarceration has gained traction in reducing penal incarceration in the United States. In this report in collaboration with the Detention Watch Network, we detail select case examples of jails and prisons that closed for one purpose, only to cage a different group of people. The case studies demonstrate how sustained pressure and community organizing can lead to transformative wins that can help free people and keep cages shut down for good