Limits on the Emission of Gamma Rays from M31 (The Andromeda Galaxy) with HAWC

The detection of the Fermi Bubbles suggests that spiral galaxies such as the Milky Way can undergo active periods. Using gamma-ray observations, we can investigate the possibility that such structures are present in other nearby galaxies. We have analyzed the region around the Andromeda Galaxy (Messier Catalog M31) for signs of bubble-like emission using TeV gamma-ray data recorded by the High-Altitude Water Cherenkov Observatory. We fit a model consisting of two 6 kpc bubbles symmetric about and perpendicular to the M31 galactic plane and assume a power-law distribution for the gamma-ray flux. We compare the emission from these bubble regions to that expected from structures similar to the Fermi Bubbles found in the Milky Way. No significant emission was observed. We report upper limits on the TeV flux from Fermi Bubble structures in M31.Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contribution

Multidimensional Simulations of Non-linear Cosmic Ray Production in Supernova Remnant Evolution

When a high-mass star (& 4Msun) explodes at the end of its life, a supernova occurs, leaving its degenerate core and a fast-moving shell of matter, known as a supernova remnant (SNR). The SNR shell lasts for many thousands of years, generating emissions from low-frequency radio (~ 10-7 eV) up to γ-ray regime (~ 1015 eV). It is also believed that SNRs are the predominant source of galactic cosmic rays, accelerating a population of thermal ions, primarily protons, up to relativistic energies by means of the diffusive shock acceleration (DSA) mechanism. The small population of thermal (Boltzmann) particles, p ~ 10-3 eV, that are accelerated to relativistic energies, p ~ 1015 eV, extract a significant amount of energy from the SNR shell. The existence of a small but highly energetic population of non-thermal particles feeds back into the dynamic evolution of the SNR, which, in turn, affects the production of new particles and the continued acceleration of particles already swept up in the shock. Much research has been done in investigating the case of particles accelerated in spherically symmetric SNRs; we present here the first simulations of supernova remnant evolution with nonlinear cosmic ray feedback in multiple dimensions. The research here presents a new approach to an old problem, allowing for a deeper investigation into the role of cosmic ray production in supernova remnant environments. The findings here show that, at the early stages of SNR evolution, the presence of cosmic rays in the shocks modifies the growth of hydrodynamic instabilities; severely damping the Rayleigh-Taylor instabilities in particular. We also find that the young remnant produces a strong TeV population of CRs that can generate TeV emissions that could be observed with or without the SNR interacting with an adjacent molecular cloud. However, the GeV emissions that could distinguish between the hadronic and leptonic population of CRs could not be observed by Fermi-LAT without the interacting molecular cloud

Human Endothelial Progenitor Cells: A Novel and Promising Cellular Therapy For Regenerative Medicine

Endothelial progenitor cells represent a novel and promising therapy for a myriad of tissues and conditions including diseases and disorders of the liver and small intestine. Cirrhosis and other diseases have created a need for a readily available supply of hepatocytes and supporting cells in diseased and scarred liver. Following chemo/radiation therapy and inflammatory bowel disease, the cell populations of the small intestine are diminished and a cell therapy for the replenishment of these populations is needed. Additionally, the cellular makers to identify both EPCs and mesenchymal stem cells (MSCs) have been defined in the literature but a debate remains as to the heterogenic vs. homogenic nature of the cell populations. This dissertation investigates the engraftment potential of EPCs in the liver when transplanted (Tx) In Utero into the pre-immune sheep model via two routes of injection, Intra-hepatic (IH) and Intra-peritoneal (IP). Upon finding engraftment, the contribution of these cells to vasculature and parenchymal tissue as well as their differentiative potential in contribution to the developing liver was investigated. Tx EPCs engraft albeit at low levels but preferentially associate with vasculature. In addition to their association with vasculature, the EPCs maintain the expression of endothelial markers in addition to expressing markers raging from fully differentiated hepatic cells to liver stem cells. In addition to their contribution to the liver, EPCs not only engraft into the small intestine but do so in a preferential manner in the area containing the crypts of Lieberkühn (above the muscularis mucosa and below the crypt-villus junction). Upon transplantation, these cells actively engraft and differentiate into both intestinal stem cells (ISCs) and into the supporting cell types of the ISC niche as well as mature cells of the intestinal parenchyma. Finally, LAM-PCR and LM-PCR were employed to identify vector integration sites in both MSCs and EPCs transfected with a variety of retroviruses. These experiments are designed to address the existence of a heterogeneous or homogenous population in both the EPC and MSC populations. Further testing on an experimental sample reveals the presence of chimeric DNA in the sample and successful amplification of integration sites in this sample is pending further investigation

Driver Workload Management During Cell Phone Conversations Chip Wood,

This study tested if intelligently suspending cell phone conversationsduring demanding driving situations would improve driver’s performance andlessen subjective workload. Using a simulator, drivers followed a lead carapproximately 2 secs ahead and braking randomly. The drivers engaged inspontaneous “Neutral,” “Intense,” or “No” cell phone conversations with theexperimenter, who sustained all conversations with scripted non-directiveutterances. When the lead car started to decelerate, the conversations weresuspended or not for the duration of the event. Objective driving performance andsubjective “workload” estimates showed significant differences betweenconversation topic types. Engaging in an “Intense” conversation duringdeceleration produced (1) smaller decreases in forward velocity, and (2) delays inreleasing the accelerator, applying the brake and decelerating. Suspending“Intense” conversations counteracted these effects, producing larger decreases inforward velocity, and speeding up drivers’ responses on the vehicle controls.Furthermore, suspending conversations clearly increased drivers’ headways andtemporal distances with the lead car. The results show that cell phoneconversation intensity has significant effects on both performance and workload.The results also show positive effects of suspending cell phone conversationsduring critical driving situations on driver performance, thus perhapscounteracting the negative effects of the workload imposed by the conversations.Subjective ratings and value judgments for this system indicate generally positiveassessments of the system