Faraday Conversion in Turbulent Blazar Jets

Low ($\lesssim 1\%$) levels of circular polarization (CP) detected at radio frequencies in the relativistic jets of some blazars can provide insight into the underlying nature of the jet plasma. CP can be produced through linear birefringence, in which initially linearly polarized emission produced in one region of the jet is altered by Faraday rotation as it propagates through other regions of the jet with varying magnetic field orientation. Marscher has begun a study of jets with such magnetic geometries using the Turbulent Extreme Multi-Zone (TEMZ) model, in which turbulent plasma crossing a standing shock in the jet is represented by a collection of thousands of individual plasma cells, each with distinct magnetic field orientations. Here we develop a radiative transfer scheme that allows the numerical TEMZ code to produce simulated images of the time-dependent linearly and circularly polarized intensity at different radio frequencies. In this initial study, we produce synthetic polarized emission maps that highlight the linear and circular polarization expected within the model.Comment: 17 pages, 13 figures, accepted for publication in Ap

"Orphan" γ\gamma-ray Flares and Stationary Sheaths of Blazar Jets

Blazars exhibit flares across the entire electromagnetic spectrum. Many $\gamma$-ray flares are highly correlated with flares detected at longer wavelengths; however, a small subset appears to occur in isolation, with little or no correlated variability at longer wavelengths. These "orphan" $\gamma$-ray flares challenge current models of blazar variability, most of which are unable to reproduce this type of behavior. Macdonald et al. have developed the Ring of Fire model to explain the origin of orphan $\gamma$-ray flares from within blazar jets. In this model, electrons contained within a blob of plasma moving relativistically along the spine of the jet inverse-Compton scatter synchrotron photons emanating off of a ring of shocked sheath plasma that enshrouds the jet spine. As the blob propagates through the ring, the scattering of the ring photons by the blob electrons creates an orphan $\gamma$-ray flare. This model was successfully applied to modeling a prominent orphan $\gamma$-ray flare observed in the blazar PKS 1510$-$089. To further support the plausibility of this model, Macdonald et al. presented a stacked radio map of PKS 1510$-$089 containing the polarimetric signature of a sheath of plasma surrounding the spine of the jet. In this paper, we extend our modeling and stacking techniques to a larger sample of blazars: 3C 273, 4C 71$.$01, 3C 279, 1055$+$018, CTA 102, and 3C 345, the majority of which have exhibited orphan $\gamma$-ray flares. We find that the model can successfully reproduce these flares, while our stacked maps reveal the existence of jet sheaths within these blazars.Comment: 19 pages, 27 figures, accepted for publication in ApJ. arXiv admin note: text overlap with arXiv:1505.0123

Transcriptional regulation of the interferon genes

Interferons (IFNs) are a class of regulatory cytokines capable of inducing a non-specific antiviral activity in target cells. Under normal conditions the synthesis of IFN is not usually detectable, but following exposure of cells to inducers such as virus or double stranded RNA, IFN is produced in large amounts. Expression of the IFN genes is tissue specific and comes about by the activation of transcription. Cis-acting virus responsive elements (VREs) responsible for transcriptional activation have been identified within the 5'-flanking sequences of the human IFN-alpha1 and -beta genes and show considerable sequence similarity

Order & disorder: a study of the flaring properties and polarized emission of blazars

Blazars are the most luminous persistent and enigmatic objects in the sky. They constitute a sub-class of active galactic nuclei (AGN) whose relativistic plasma jets are closely aligned to our line of sight. By monitoring the polarized emission of these jets and subsequently modeling flares in the high-energy emission, we are able to gain insight into the parsec-scale physics of the jets close to the central engines. My dissertation develops and augments several theoretical models of high-energy blazar emission. The vast majority of gamma-ray flares detected in blazars are highly correlated with flares detected at longer wavelengths; however, a small subset of these gamma-ray flares appear to occur in isolation. These "orphan" gamma-ray flares challenge current models of blazar variability. I have developed a theoretical model of blazar emission to explain the origin of these orphan flares. This model invokes the presence of a sheath of plasma enshrouding the relativistic spine of the jet. The sheath supplies photons that are inverse-Compton scattered up to high energies by relativistic electrons contained within the jet, producing an orphan flare. This model is successfully applied to a number of such gamma-ray flares. In addition, I present stacked radio images that highlight the presence of jet sheaths in my sample of blazars. Circular polarization (CP) has been detected in a number of blazar jets. CP is very sensitive to the underlying plasma content of the jet. A. Marscher has developed the Turbulent Extreme Multi-Zone (TEMZ) model for blazar emission consisting of thousands of individual cells of plasma that propagate relativistically across a standing shock in the jet. The turbulent nature of the magnetic field within the TEMZ grid naturally creates a birefringent environment in which CP emission can be produced. In order to investigate whether the TEMZ model can indeed produce CP, I have developed a numerical algorithm to solve the full Stokes equations of polarized radiative transfer. I apply this algorithm to ray tracing through the TEMZ model. I am able to demonstrate that TEMZ can reproduce CP at the levels present in blazars

Basic Life Support and Opioid Overdose Management: Knowledge and Attitudes Among Students Matriculating into Medical School - A Cross-Sectional Analysis to Inform Curricular Change

Purpose: While Basic Life Support (BLS) skills are typically included in undergraduate medical education (UME) curricula, graduating students continue to demonstrate substandard skills retention. In the setting of the opioid epidemic, effective opioid overdose management (OOM) training should likewise take place during UME. To date, there is a paucity of literature that describes incoming medical students’ knowledge and attitudes on these topics prior to beginning their studies. The purpose of this study is to describe medical students’ knowledge and attitudes towards BLS and OOM prior to their medical training to inform curricular change in UME. Methods: We conducted an observational, cross-sectional study of 1st-year medical students at a major academic medical school in Philadelphia, the epicenter of the opioid epidemic. Survey items assessed participants’ knowledge and attitudes on BLS and OOM. The survey was voluntary and deployed through Qualtrics. Results and Conclusions: 258 students of 272 (95% response rate) completed the survey. 32% of respondents had been previously certified in BLS / ACLS, and only 15% had previously received any level of OOM training. Students reported a moderate comfort level with administering chest compressions (5.14 [Likert Scale 1-10, 10=most comfortable]); and a low comfort level using an AED (4.80 3.1) or assisting an opioid victim (3.74 3.1). Up to 74% failed to correctly answer knowledge-based questions regarding basic management principles. Matriculating students do not have adequate BLS or OOM knowledge upon entering medical school, but wish to have these skills taught to them during their pre-clinical training. Findings should inform UME curricular changes to address the growing opioid epidemic

Structured Reflective Communication as a Meta-Genre in Teacher Education: Creative Uses of Critique in a Teacher Education Program

Critical reflection is central to teacher education for unpacking privileged positions and empowering participants to adopt valued professional stances (e.g. Krull, Oras & Sisask, 2007; Harford & MacRuairc, 2008; Fernandez, 2010), yet critical reflection is not a well-developed conceptual structure within teacher education. Lesson planning is, likewise, central to teacher education, yet not well-developed as a theoretical tool. Our model proposes a way of engaging beginning teachers in critical reflection by drawing together the informal spoken discourse meanings of critical reflection in education, its more formalised structure as critique in rhetoric and genre analysis, and lesson planning. When critical reflection in education is seen as a type of structured reflective communication, which includes both spoken and written components of “knowing and doing”, eight key connections emerge between the elements of a critique and lesson planning. By linking critique and lesson planning as components of a meta-genre of structured reflective communication, teacher trainers with a useful set of empowering tools for beginning teachers to connect theory with practice in their lesson planning