X-ray Diagnostics of Relativistic Reflection Around Supermassive Black Holes

This thesis presents an investigation into the X-ray energy and variability spectra of Seyfert galaxies. Reflection of the X-ray continuum by the accretion disc in these Active Galactic Nuclei (AGN) is expected to produce an iron line and an associated reflection continuum. The iron line should be relativistically broadened as it is subject to the strong gravitational field of the central black hole. Often, such a line is never found either because it appears not to be present or if it is, the magnitude of the broadening is less than expected. These cases pose a problem for the current understanding of accretion onto the black hole in AGN. We analyse the XMM-Newton observations of such objects to determine if the relativistically broadened iron line only appears to be “missing” because the accretion disc is ionised and/or there is a strong concentration of the line emission in the central disc regions. In the latter scenario, it is possible for the iron line to be smeared to such an extent that it blends into the continuum and is therefore difficult to disentangle. A combination of both effects leads to the identification of a relativistically broadened iron line in the majority of the observations where it could not be detected previously. In some of these objects, blurred disc reflection can also be detected if there is an additional source of iron line emission that arises further from the black hole such as in the Broad Line Region. We find that the strength of the blurred iron line and associated reflection continuum in these objects is consistent with the sources that exhibit a “classical” relativistically broadened iron line. Following this, we investigate the variability of the iron line in our sample of Seyferts. In models of accretion disc reflection, a simple prediction is that variations in the reflection component should follow variations in the X-ray continuum that illuminates the disc. Using unnormalised rms variance-spectra, we investigate if this scenario is typical in our sample of observations and find that it is not generally confirmed. Instead, there is a large amount of diversity in the behaviour of the iron line variability. For example, some observations possess an iron line that is more variable than the continuum, while other iron lines exhibit variability only bluewards of the line core. Most interestingly, a large group of observations possess a broad iron line that is invariant to the continuum and there are changes in the variability of the iron line between multiple observations of the same object. In some cases, the rms spectra can distinguish between models that explain the broad red wing of the iron line. Finally, we expand the variability analysis to between 0.3 – 10 keV and focus on the broadband X-ray variability on short time-scales (~ 40 ks). After normalising the variance spectra by the X-ray flux, a diverse range of amplitudes and shapes are found in the variance-spectra of both different objects and the same object. Part of the scatter in the amplitudes is due to the anti-correlation between the black hole mass of an AGN and its variance, while the various classes of profile shapes suggest that there are intrinsic differences in the spectral variability throughout the sample, as found with the iron line. We model variance-spectra that are based on relativistic disc reflection and velocity-smeared models of the broadband X-ray spectra of AGN and find that a range of profile shapes are possible. The mean variance-spectrum of those that are humped in the sample can be explained solely by a small increase in the slope of the continuum as the X-ray flux increases in a reflection-based model. Interestingly, there is no requirement for either the disc reflection or absorbers local to the AGN to respond to the changing illuminating intensity

X-ray Diagnostics of Relativistic Reflection Around Supermassive Black Holes

This thesis presents an investigation into the X-ray energy and variability spectra of Seyfert galaxies. Reflection of the X-ray continuum by the accretion disc in these Active Galactic Nuclei (AGN) is expected to produce an iron line and an associated reflection continuum. The iron line should be relativistically broadened as it is subject to the strong gravitational field of the central black hole. Often, such a line is never found either because it appears not to be present or if it is, the magnitude of the broadening is less than expected. These cases pose a problem for the current understanding of accretion onto the black hole in AGN. We analyse the XMM-Newton observations of such objects to determine if the relativistically broadened iron line only appears to be “missing” because the accretion disc is ionised and/or there is a strong concentration of the line emission in the central disc regions. In the latter scenario, it is possible for the iron line to be smeared to such an extent that it blends into the continuum and is therefore difficult to disentangle. A combination of both effects leads to the identification of a relativistically broadened iron line in the majority of the observations where it could not be detected previously. In some of these objects, blurred disc reflection can also be detected if there is an additional source of iron line emission that arises further from the black hole such as in the Broad Line Region. We find that the strength of the blurred iron line and associated reflection continuum in these objects is consistent with the sources that exhibit a “classical” relativistically broadened iron line. Following this, we investigate the variability of the iron line in our sample of Seyferts. In models of accretion disc reflection, a simple prediction is that variations in the reflection component should follow variations in the X-ray continuum that illuminates the disc. Using unnormalised rms variance-spectra, we investigate if this scenario is typical in our sample of observations and find that it is not generally confirmed. Instead, there is a large amount of diversity in the behaviour of the iron line variability. For example, some observations possess an iron line that is more variable than the continuum, while other iron lines exhibit variability only bluewards of the line core. Most interestingly, a large group of observations possess a broad iron line that is invariant to the continuum and there are changes in the variability of the iron line between multiple observations of the same object. In some cases, the rms spectra can distinguish between models that explain the broad red wing of the iron line. Finally, we expand the variability analysis to between 0.3 – 10 keV and focus on the broadband X-ray variability on short time-scales (~ 40 ks). After normalising the variance spectra by the X-ray flux, a diverse range of amplitudes and shapes are found in the variance-spectra of both different objects and the same object. Part of the scatter in the amplitudes is due to the anti-correlation between the black hole mass of an AGN and its variance, while the various classes of profile shapes suggest that there are intrinsic differences in the spectral variability throughout the sample, as found with the iron line. We model variance-spectra that are based on relativistic disc reflection and velocity-smeared models of the broadband X-ray spectra of AGN and find that a range of profile shapes are possible. The mean variance-spectrum of those that are humped in the sample can be explained solely by a small increase in the slope of the continuum as the X-ray flux increases in a reflection-based model. Interestingly, there is no requirement for either the disc reflection or absorbers local to the AGN to respond to the changing illuminating intensity

Social and peer influences in college choice

College is a high involvement decision making where students are expected to evaluate several college offerings before selecting a college or a course to study. However, even in high involvement product like college, students get influenced by opinion leaders and suffer from social contagion. This narrative style study, involving 98 first year students, was able to demonstrate that social contagion differs with regards to gender, ethnicity and personality. Recommendations from students with academically strong background would impact on the college choice of the undergraduate students and limit information search. Study was able to identify the incidence of anchoring heuristics amongst the students. Managerial implications with regards to design of marketing campaign follows at the end of the study

The difficult act of balancing financial and academic performance: Product adaptation strategies at university branch campuses

Adapting a product to suit local requirements is a well-known international marketing strategy. Branch campuses generally adapt programs to suit local requirements. However, the academic fraternity has resisted adaptation on concerns about the dilution of academic standards. This study uses data from five branch campuses to examine the link between adaptation and financial and academic performance. The results indicate that adaption leads to increased financial performance but does not maintain academic standards. The study recommends strategies to maintain a balance between an ethnocentric approach, which calls for similar academic standards, and a geocentric approach, which requires adaptation

The Influence of Premium Finished Paper Packaging on Consumer Behavior

Companies face the challenge of determining the return on investment of premium paper packaging features, such as substrate thickness and finishing options. If companies can better understand how consumers perceive “premium,” they could channel their focus on specific design elements and maximize their returns (Dwivedi & Nayeem, 2018). Touch is a critical factor in driving consumer behavior and purchase decisions and influencing trust between brands and consumers (Krishna et al. 2017). While previous studies have explored the impact of design elements like size, shape, color, and font on consumer behavior, this research investigates the influence of touch, substrate, print finishes (foil, emboss, and gloss), unboxing experiences of direct mail, and consumer packaged goods. The study employed three unique in-person environments, which collected participant data through eye-tracking, facial expressions analysis, touch coding, and surveys across various consumer activities. Results indicate that premium packaging generates higher engagement and positive responses from consumers in retail and at-home settings. Foil finish outperforms in the retail environment for unfamiliar CBD serum (P \u3c 0.0001). Touch is shown to be a better predictor of sales than visual attention across multiple packaging finishes, including foil (P = 0.002), glossy (P = 0.006), embossed (P = 0.007), and no finish (P = 0.028). All participant touches were identified and coded, revealing four unique touch actions (feel, pick up, compare, put in cart). Premium paperboard packaging evokes more positive facial expressions in consumer electronics unboxing and more interaction with direct mail. Notably, prominently displaying discount codes increases consumer engagement. Direct mail results reveal that circular mail was widely perceived as recyclable, tri-folds were retained the most, while postcards were more likely to be discarded. These findings have practical implications for businesses, enabling them to optimize packaging strategies, drive consumer engagement, and promote environmentally friendly practices

Identification of trends in racial/ethnic disparities of patients with diabtes mellitus using web-based tableau dashboard- a cross sectional study

Many ways of creating data visualizations using the Business Intelligence tools have been implemented and new ways are continuously evolving. In this project, I have used Tableau Public software to analyze the trends of Race and Ethnic disparities in Diabetes Mellites patients by creating individual dashboards. A desktop application was created using the web programming languages like HTML and CSS to create more interactive and application embedded dashboard. The dataset selected was Health Facts® database, which is contributed of day-to-day patient care encounters. Data preparation and data pre-processing and data visualization were the two major steps to get the required results. In Data pre-processing, data mining tools such as SQL and Python were used to create the final dataset with 7 variables. An infographic was created with a dashboard with three views embedded into web pages. These three dashboard views were created based their specific information like one dashboard view showing the insights about the distribution of Hispanic with Diabetes Mellitus, another dashboard view showing the trends of African American and Caucasian races and the third view showing the distribution of patients with Diabetes Mellitus and specific cancers based on race and ethnicity. All the data obtained were analyzed and compared with the CDC data and the results confirmed. Moreover, to measure the usability of the desktop application, SUS (System Usability Score) was used. The result of the application clearly indicated the way such application can be used strategize the programs and interventions to reduce the disparities for Diabetes Mellitus amongst the African American population

An analysis of techniques for obtaining speedup in software solutions for proteomics

Proteomics is the study of the structure and behavior of proteins. In order to perform this kind of an analysis, proteins are broken down into their constituent peptides, and values of different parameters are recorded. The amount of this kind of data collected is very large, and therefore analysis of this data becomes time-consuming. To overcome this issue, there have been several software developed for processing protein data. With a large number of software solutions available in the market, the decision about which one to use is hard for the end-user. The expectations from such a software for each user vary. Apart from the end-users, there are software developers working on improving the quality of the existing software by implementing suitable optimization techniques. This study therefore proposes a comparison framework for software solutions for proteomics that will benefit the readers by providing all the information required in order to make a decision about the software that is suitable for their needs

Robotic assisted Laparoscopic partial Nephrectomy for suspected Renal Cell Carcinoma: Retrospective review of surgical outcomes of 35 Cases

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Determination of dissociation constants of protein ligands by thermal shift assay

The thermal shift assay (TSA) is a powerful tool used to detect molecular interactions between proteins and ligands. Using temperature as a physical denaturant and an extrinsic fluorescent dye, the TSA tracks protein unfolding. This method precisely determines the midpoint of the unfolding transition (Tm role= presentation \u3e), which can shift upon the addition of a ligand. Though experimental protocols have been well developed, the thermal shift assay data traditionally yielded qualitative results. Quantitative methods for Kd role= presentation \u3e determination relied either on empirical and inaccurate usage of Tm role= presentation \u3e or on isothermal approaches, which do not take full advantage of the melting point precision provided by the TSA. We present a new analysis method based on a model that relies on the equilibrium system between the native and molten globule state of the protein using the van\u27t Hoff equation. We propose the Kd role= presentation \u3e can be determined by plotting Tm role= presentation \u3e values versus the logarithm of ligand concentrations and fitting the data to an equation we derived. After testing this procedure with the monomeric maltose-binding protein and an allosterically regulated homotetrameric enzyme (ADP-glucose pyrophosphorylase), we observed that binding results correlated very well with previously established parameters. We demonstrate how this method could potentially offer a broad applicability to a wide range of protein classes and the ability to detect both active and allosteric site binding compounds