X-ray Astrophysics: The Spoiler Clusters and XRISM Synchrotron Calibrations

Cool core galaxy clusters hosting brightest cluster galaxies (BCGs) in their centres radiate away their energy on timescales of less than 10^9 yr. If cooling wasn't offset by some form of heating, the hot atmosphere would cool and continuously form stars at rates of hundreds to thousands of solar masses per year. However, observations by Chandra have revealed no evidence of gas cooling at these expected rates. Instead, predicted cooling rates are counteracted via mechanical feedback from active galactic nuclei (AGN), which heats the intracluster medium (ICM) and suppresses cooling. Observations have shown that nebular emission and molecular gas in BCGs are associated with rising X-ray bubbles inflated by radio jets launched by massive black holes. Molecular clouds have either condensed from low entropy gas being uplifted in the wakes of X-ray bubbles or can be lifted directly. In this thesis I present an analysis of a sample of five cool-core galaxy clusters (A2029, A2151, A2107, EXO0422-086, RBS0533) observed with the Chandra X-ray Observatory selected on the basis of having an upper limit on Halpha emission in the ACCEPT database, yet with short central cooling times. I extract thermodynamic profiles for each cluster and show that the central cooling time and entropy falls below 1 Gyr and 30 kev cm^2 respectively. I thoroughly explore each cluster for evidence of X-ray bubbles, and discuss a method of detecting and confirming the significance of bubbles. Only RBS0533 has detectable radio/X-ray bubbles which are commonly associated with cooling atmospheres. Although, despite its prominent X-ray bubble, RBS0533 lacks significant levels of molecular gas. I argue that cold gas is absent at appreciable levels in these systems because radio bubbles are either absent or in the case of RBS0533, its radio bubbles are unable to lift low entropy atmospheric gas to an altitude where the ratio of the cooling time to the free-fall time falls below unity. I also search for signatures of uplifted gas in our sample by creating metallicity maps and extracting thermodynamic profiles along radio jet axis and ``off" of radio jet axis' to determine if metal enriched gas preferentially lies along the former. Inspection of maps and subsequent statistical analysis of profiles confirms that metal-rich plasma does not preferentially lie along any direction. Finally, I present an analysis of my work during a filter calibration project for the X-ray Imaging and Spectroscopy Mission (XRISM), where I assisted in the calibration of a set of Resolve optical blocking filters (IVCS-6 and OVCS-7A) using metrology synchrotron beamlines at the Canadian Light Source and Advanced Light Source

Yukawa Potential Orbital Energy: Its Relation to Orbital Mean Motion as well to the Graviton Mediating the Interaction in Celestial Bodies

Research on gravitational theories involves several contemporary modified models that predict the existence of a non-Newtonian Yukawa-type correction to the classical gravitational potential. In this paper we consider a Yukawa potential and we calculate the time rate of change of the orbital energy as a function of the orbital mean motion for circular and elliptical orbits. In both cases we find that there is a logarithmic dependence of the orbital energy on the mean motion. Using that, we derive an expression for the mean motion as a function of the Yukawa orbital energy, as well as specific Yukawa potential parameters. Furthermore, various special cases are examined. Lastly, expressions for the Yukawa range and coupling constant are also derived. Finally, an expression for the mass of the graviton mediating the interaction is calculated using the expression its Compton wavelength (i.e., the potential range ).Numerical estimates for the mass of the graviton mediating the interaction are finally obtained at various eccentricity values and in particular at the perihelion and aphelion points of Mercury’s orbit around the sun

The Poynting–Robertson Effect in the Newtonian Potential with a Yukawa Correction

We consider a Yukawa-type gravitational potential combined with the Poynting-Robertson effect. Dust particles originating within the asteroid belt and moving on circular and elliptic trajectories are studied and expressions for the time rate of change of their orbital radii and semimajor axes, respectively, are obtained. These expressions are written in terms of basic particle parameters, namely their density and diameter. Then, they are applied to produce expressions for the time required by the dust particles to reach the orbit of Earth. For the Yukawa gravitational potential, dust particles of diameter 10-3 m in circular orbits require times of the order of 8.557 x 106 y and for elliptic orbits of eccentricities e = 0.1, 0.5 require times of 9.396 x 106 and 2.129 x 106 y respectively to reach Earth\u27s orbit. Finally, various cases of the Yukawa potential are studied and the corresponding particle times to reach Earth\u27s are derived per case along with numerical results for circular and various elliptical orbits

Vicarious Racism Stress and Disease Activity: The Black Women’s Experiences Living with Lupus (BeWELL) Study

Background: Indirect or vicarious exposure to racism (e.g., hearing about or observing acts of racism or discrimination) is a salient source of stress for African Americans. Emerging research suggests that these “secondhand” experiences of racism may contribute to racial health inequities through stress-mediated pathways. Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease that disproportionately impacts African American women and is characterized by racial disparities in severity. Health outcomes in this population may be susceptible to vicarious racism given that SLE is shown to be sensitive to psychosocial stress. Methods: Data are from 431 African American women with SLE living in Atlanta, Georgia in the Black Women’s Experiences Living with Lupus (BeWELL) Study (2015-2017). Vicarious racism stress was measured with four items assessing distress from: (1) hearing about racism in the news; (2) experiences of racism among friends or family; (3) witnessing racism in public; and (4) racism depicted in movies and television shows. Multivariable linear regression was used to examine associations with disease activity measured using the Systemic Lupus Activity Questionnaire. Results: Adjusting for sociodemographic and health-related covariates, vicarious racism stress was associated with greater disease activity (b=2.15; 95% CI=1.04-3.27). This association persisted even after adjustment for personal experiences of racial discrimination (b=1.80; 95% CI=0.67-2.92). Conclusions: Vicarious racism may result in heightened disease activity and contribute to racial disparities in SLE. Our findings suggest that acts of racism committed against members of one’s racial group may have distinct health consequences beyond the immediate victim or target

Vicarious Racism Stress and Disease Activity: The Black Women’s Experiences Living with Lupus (BeWELL) Study

BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by Black-White disparities in severity, which in part may be associated with differences in exposure to psychosocial stress. Direct interpersonal racial discrimination is a salient source of psychosocial stress among Black Americans and is an established risk factor for poor health. However, the health effects of vicarious or “secondhand” exposure to racial discrimination or racism are relatively understudied. METHODS: Data are from 431 African American women with SLE living in Atlanta, Georgia recruited to the Black Women’s Experiences Living with Lupus (BeWELL) Study (2015-2017). Vicarious racism stress was measured with four items assessing distress in response to hearing about or seeing racism in the news, through friends or family, in public, or in movies and television shows. Multivariable linear regression was used to examine associations between vicarious racism stress, direct interpersonal racial discrimination measured by the Everyday Discrimination Scale (EDS), and disease activity measured by the Systemic Lupus Activity Questionnaire which assessed SLE-related symptoms in the past three months. RESULTS: Vicarious racism stress (b=1.80; 95% Confidence Interval [CI]: 0.67, 2.92) was associated with greater disease activity, even after adjusting for direct interpersonal experiences of racial discrimination (b=1.14; 95% CI: 0.42, 1.86) and other sociodemographic and health-related covariates. CONCLUSIONS: Similar to more commonly studied direct interpersonal racial discrimination, vicarious racism may result in heightened SLE activity. Our findings suggest that acts of racism committed against members of one’s racial group may have health consequences beyond the immediate victim or target

The Use of a Game-Based Learning Platform to Engage Nursing Students: A Descriptive, Qualitative Study

Baccalaureate nursing programs require students to complete a research course, and faculty find it challenging to engage students. Educational gaming has recently gained attention as a technique to motivate students and enhance learning. The purpose of this pilot study was to describe undergraduate nursing students\u27 reflections of their experiences with 3D Gamelab©, a game-based learning platform. A descriptive qualitative research design was used to elicit students\u27 reflections of their experiences. Educational content such as handouts, videos, activities, and recommended resources for a required junior level nursing research course was organized into quests for use in 3D GameLab©. At the end of the semester, students were invited to give their feedback through a survey with open-ended questions. Thematic analysis resulted in the following components of the game-based learning experience: navigation, motivation, gaming concept, knowledge, technology, and target population. Although the overall response to 3D GameLab© in this course was negative, game-based learning does have the potential to engage students and enhance learning. To better understand how educational gaming could be used in nursing, further research should be conducted to determine the most motivating elements and the types of course content best delivered in this manner

Yukawa Potential Orbital Energy: Its Relation to Orbital Mean Motion as well to the Graviton Mediating the Interaction in Celestial Bodies

Research on gravitational theories involves several contemporary modified models that predict the existence of a non-Newtonian Yukawa-type correction to the classical gravitational potential. In this paper we consider a Yukawa potential and we calculate the time rate of change of the orbital energy as a function of the orbital mean motion for circular and elliptical orbits. In both cases we find that there is a logarithmic dependence of the orbital energy on the mean motion. Using that, we derive an expression for the mean motion as a function of the Yukawa orbital energy, as well as specific Yukawa potential parameters. Furthermore, various special cases are examined. Lastly, expressions for the Yukawa range λ and coupling constant α are also derived. Finally, an expression for the mass of the graviton mgr mediating the interaction is calculated using the expression its Compton wavelength (i.e., the potential range λ). Numerical estimates for the mass of the graviton mediating the interaction are finally obtained at various eccentricity values and in particular at the perihelion and aphelion points of Mercury’s orbit around the sun

Yukawa Potential Orbital Energy: Its Relation to Orbital Mean Motion as well to the Graviton Mediating the Interaction in Celestial Bodies

Research on gravitational theories involves several contemporary modified models that predict the existence of a non-Newtonian Yukawa-type correction to the classical gravitational potential. In this paper we consider a Yukawa potential and we calculate the time rate of change of the orbital energy as a function of the orbital mean motion for circular and elliptical orbits. In both cases we find that there is a logarithmic dependence of the orbital energy on the mean motion. Using that, we derive an expression for the mean motion as a function of the Yukawa orbital energy, as well as specific Yukawa potential parameters. Furthermore, various special cases are examined. Lastly, expressions for the Yukawa range and coupling constant are also derived. Finally, an expression for the mass of the graviton mediating the interaction is calculated using the expression its Compton wavelength (i.e., the potential range ).Numerical estimates for the mass of the graviton mediating the interaction are finally obtained at various eccentricity values and in particular at the perihelion and aphelion points of Mercury’s orbit around the sun