Investigating the Uniformity of the Excess Gamma rays towards the Galactic Center Region

We perform a composite likelihood analysis of subdivided regions within the central $26^\circ\times20^\circ$ of the Milky Way, with the aim of characterizing the spectrum of the gamma-ray galactic center excess in regions of varying galactocentric distance. Outside of the innermost few degrees, we find that the radial profile of the excess is background-model dependent and poorly constrained. The spectrum of the excess emission is observed to extend upwards of 10 GeV outside $\sim5^\circ$ in radius, but cuts off steeply between 10--20 GeV only in the innermost few degrees. If interpreted as a real feature of the excess, this radial variation in the spectrum has important implications for both astrophysical and dark matter interpretations of the galactic center excess. Single-component dark matter annihilation models face challenges in reproducing this variation; on the other hand, a population of unresolved millisecond pulsars contributing both prompt and secondary inverse Compton emission may be able to explain the spectrum as well as its spatial dependency. We show that the expected differences in the photon-count distributions of a smooth dark matter annihilation signal and an unresolved point source population are an order of magnitude smaller than the fluctuations in residuals after fitting the data, which implies that mismodeling is an important systematic effect in point source analyses aimed at resolving the gamma-ray excess.Comment: 27 pages, 9 figures. Matches accepted version: references added, typo corrected in Sec. 4.2, some additional discussion added (results unchanged

The Galactic Isotropic γ\gamma-ray Background and Implications for Dark Matter

We present an analysis of the radial angular profile of the galacto-isotropic (GI) $\gamma$-ray flux--the statistically uniform flux in circular annuli about the Galactic center. Two different approaches are used to measure the GI flux profile in 85 months of Fermi-LAT data: the BDS statistic method which identifies spatial correlations, and a new Poisson ordered-pixel method which identifies non-Poisson contributions. Both methods produce similar GI flux profiles. The GI flux profile is well-described by an existing model of bremsstrahlung, $\pi^0$ production, inverse Compton scattering, and the isotropic background. Discrepancies with data in our full-sky model are not present in the GI component, and are therefore due to mis-modeling of the non-GI emission. Dark matter annihilation constraints based solely on the observed GI profile are close to the thermal WIMP cross section below 100 GeV, for fixed models of the dark matter density profile and astrophysical $\gamma$-ray foregrounds. Refined measurements of the GI profile are expected to improve these constraints by a factor of a few.Comment: 20 pages, 15 figures, references adde

Modeling of power electronic systems with EMTP

In view of the potential impact of power electronics on power systems, there is need for a computer modeling/analysis tool to perform simulation studies on power systems with power electronic components as well as to educate engineering students about such systems. The modeling of the major power electronic components of the NASA Space Station Freedom Electric Power System is described along with ElectroMagnetic Transients Program (EMTP) and it is demonstrated that EMTP can serve as a very useful tool for teaching, design, analysis, and research in the area of power systems with power electronic components. EMTP modeling of power electronic circuits is described and simulation results are presented

SOCIOECONOMIC AND INSTITUTIONAL DETERMINERS OF DURABLE TECHNOLOGICAL INNOVATIONS IN THE FOOD-PRODUCING AGRICULTURE OF CAMEROON

The challenges posed by food security for populations in sub-Saharan Africa and the fact that extensive production systems are reaching their limits in food-producing agriculture imply accelerating technological innovation toward ecological intensification of agricultural production systems. A review of research on plantain banana in Cameroon since 1988 revealed how institutional innovation enabled hybridization of different forms of research (fundamental, systems, and action research) and reinforced the organizational innovation required for technical change. Evaluation of impacts underlined the complementarity between an increase in productivity and in income in rural areas, the production of human and social capital and the protection of forest resources.innovation, food crops, Cameroon, sustainable development, plantain, Research and Development/Tech Change/Emerging Technologies,

Comics at the Surface: Michael DeForge’s Ant Colony

The comics artist and illustrator Michael DeForge published his first graphic novel, Ant Colony, in 2014. The sophisticated combination of verbal and visual storytelling in his work has earned him the admiration of readers and critics alike, and makes him one of the most compelling practitioners of the “literary comic.” This article applies surface reading theory to reading contemporary comics, also referred to as graphic narratives or novels, taking the work of DeForge as its case study. It analyzes Ant Colony as a work of narrative art, and also as a theory of narrative art that draws our attention to the process of surface reading: whether to the surfaces of bodies, the surfaces of language, or the surface of the comic book page. Running counter to a close reading practice that assumes that a deeper meaning is hidden in the text, DeForge’s work redirects the reader’s eye to the form of the text itself. This redirection posits an open acceptance, and scrutiny, of the surface: close reading through attention to form

Reproducing Oceanographic Processes in a Rotating Tank to Demonstrate Conceptual Principals in Undergraduate Classes for Non-Science Majors

OCN 499 - Undergraduate Thesi

Still Moving: Gabrielle Bell’s Graphic Auto-Fiction

In Lucky, The Voyeurs, and Truth is Fragmentary, cartoonist Gabrielle Bell adopts comics panels of approximately the same size as a passport photo. The comics draw a kind of auto-fiction that marries the fantastical and the autobiographical, frequently eliding musings on her status as a woman writer, a comics writer, and a traveler. These are all categories that share the distinction of being “threshold” or liminal categories. This chapter takes Bell’s presentation of identity as an object of formal and phenomenological inquiry. It considers how the hand-drawn rendering of the autobiographical self ironically draws attention to the irregularity of identity and to the writer’s unmistakable signature that extends to both verbal and visual style. Taking representative scenes from these three graphic short-story collections, the author argues the stories demonstrate a writing practice that claims the liminal as an authoritative expression of individual identity for the twenty-first century