3D electron density distributions in the solar corona during solar minima: assessment for more realistic solar wind modeling

Knowledge of the electron density distribution in the solar corona put constraints on the magnetic field configurations for coronal modeling and on initial conditions for solar wind modeling. We work with polarized SOHO/LASCO-C2 images from the last two recent minima of solar activity (1996-1997 and 2008-2010), devoid of coronal mass ejections. The goals are to derive the 4D electron density distributions in the corona by applying a newly developed time-dependent tomographic reconstruction method and to compare the results between the two solar minima and with two magnetohydrodynamic models. First, we confirm that the values of the density distribution in thermodynamic models are more realistic than in polytropic ones. The tomography provides more accurate distributions in the polar regions, and we find that the density in tomographic and thermodynamic solutions varies with the solar cycle in both polar and equatorial regions. Second, we find that the highest-density structures do not always correspond to the predicted large-scale heliospheric current sheet or its helmet streamer but can follow the locations of pseudo-streamers. We deduce that tomography offers reliable density distributions in the corona, reproducing the slow time evolution of coronal structures, without prior knowledge of the coronal magnetic field over a full rotation. Finally, we suggest that the highest-density structures show a differential rotation well above the surface depending on how they are magnetically connected to the surface. Such valuable information on the rotation of large-scale structures could help to connect the sources of the solar wind to their in situ counterparts in future missions such as Solar Orbiter and Solar Probe Plus.Comment: 23 pages, 9 figure

The Experiences and Perceptions of African American Women Who Reside in Nursing Homes

The purpose of this qualitative case study was to examine the experiences and perceptions of African American women who reside in a nursing home and to understand African American women\u27s decisions for admitting to the facility. Social Learning Theory was applied to answer the question of how African American women\u27s experiences and perceptions toward long-term care influence healthcare decisions and admission to a nursing home. Eleven participants interviewed in the study were at least 60 years old, admitted into the facility within the past two years and who had not previously resided in a nursing home. Yin\u27s five step approach to data analysis, NVivo and Microsoft Office to gather data from African American women who live in a nursing home. Participants in this study described their perceptions of nursing homes as places they never thought they would reside in and expressed that African American families traditionally took care of their own. As a result, participants stated nursing homes were not an option normally considered within their families. Decisions to admit to a nursing home were based on family work schedules which resulted in lack of supervision at home, increased nursing care, and financial reasons. Cultural competence was an important factor in helping them adjust to a nursing home environment despite cultural norms. This research can contribute to social change by providing awareness and identifying health behaviors and cultural beliefs regarding the use of long-term care facilities by African American women despite cultural norms. The findings of this study can also create positive social change movement in nursing homes to deliver resident-centered care and empowering staff

Journeyman International: Third Lens Ministries Development in Jonestown, Mississippi

Jonestown, Mississippi has been known to be a place of poverty and in need of infrastructure. A nonprofit, Third Lens Ministries is developing housing for the people of Jonestown, Mississippi. Over the last 9 months, an architect Margy Maher, an engineer Autumn Wagner, as well as myself, a construction management major, have all collaborated in order to design, engineer and plan the perfect Dwelling for the people of Jonestown, Mississippi. While the scope of the project includes community centers and housing, our team’s scope was to focus on the residential development and site work. As the construction manager, my deliverables are the construction scope analysis, which describes each piece of the work performed, a hazard mitigation analysis showing how natural disasters, crime and insect infestations will be mitigated, a construction safety plan outlining safety concerns, preventative maintenance and procedures, a storm water pollution prevention plan outlining how large rainfall will be handled and maintained on site, a site logistics plan showing phasing, material laydown, trailers, path of travel and phasing, an estimate broken into subcategories based on CSI formatting and finally a schedule describing each phase of the project beginning with utilities, residential structures and then site work

An Analytic Center Cutting Plane Method to Determine Complete Positivity of a Matrix

We propose an analytic center cutting plane method to determine if a matrix is completely positive, and return a cut that separates it from the completely positive cone if not. This was stated as an open (computational) problem by Berman, D\"ur, and Shaked-Monderer [Electronic Journal of Linear Algebra, 2015]. Our method optimizes over the intersection of a ball and the copositive cone, where membership is determined by solving a mixed-integer linear program suggested by Xia, Vera, and Zuluaga [INFORMS Journal on Computing, 2018]. Thus, our algorithm can, more generally, be used to solve any copositive optimization problem, provided one knows the radius of a ball containing an optimal solution. Numerical experiments show that the number of oracle calls (matrix copositivity checks) for our implementation scales well with the matrix size, growing roughly like $O(d^2)$ for $d\times d$ matrices. The method is implemented in Julia, and available at https://github.com/rileybadenbroek/CopositiveAnalyticCenter.jl.Comment: 16 pages, 1 figur

Complexity analysis of a sampling-based interior point method for convex optimization

We develop a short-step interior point method to optimize a linear function over a convex body assuming that one only knows a membership oracle for this body. The approach is based on Abernethy and Hazan's sketch of a universal interior point method using the so-called entropic barrier [arXiv 1507.02528v2, 2015]. It is well-known that the gradient and Hessian of the entropic barrier can be approximated by sampling from Boltzmann-Gibbs distributions, and the entropic barrier was shown to be self-concordant by Bubeck and Eldan [arXiv 1412.1587v3, 2015]. The analysis of our algorithm uses properties of the entropic barrier, mixing times for hit-and-run random walks by Lovász and Vempala [Foundations of Computer Science, 2006], approximation quality guarantees for the mean and covariance of a log-concave distribution, and results from De Klerk, Glineur and Taylor on inexact Newton-type methods [arXiv 1709.0519, 2017]

Simulated annealing with hit-and-run for convex optimization: rigorous complexity analysis and practical perspectives for copositive programming

We give a rigorous complexity analysis of the simulated annealing algorithm by Kalai and Vempala [Math of OR 31.2 (2006): 253-266] using the type of temperature update suggested by Abernethy and Hazan [arXiv 1507.02528v2, 2015]. The algorithm only assumes a membership oracle of the feasible set, and we prove that it returns a solution in polynomial time which is near-optimal with high probability. Moreover, we propose a number of modifications to improve the practical performance of this method, and present some numerical results for test problems from copositive programming

An analytic center cutting plane method to determine complete positivity of a matrix

We propose an analytic center cutting plane method to determine whether a matrix is completely positive and return a cut that separates it from the completely positive cone if not. This was stated as an open (computational) problem by Berman et al. [Berman A, Dur M, Shaked-Monderer N (2015) Open problems in the theory of completely positive and copositive matrices. Electronic 1. Linear Algebra 29(1):46-58]. Our method optimizes over the intersection of a ball and the copositive cone, where membership is determined by solving a mixed-integer linear program suggested by Xia et al. [Xia W, Vera JC, Zuluaga LF (2020) Globally solving nonconvex quadratic programs via linear integer programming techniques. INFORMS J. Comput 32(1):40-561 Thus, our algorithm can, more generally, be used to solve any copositive optimization problem, provided one knows the radius of a ball containing an optimal solution. Numerical experiments show that the number of oracle calls (matrix copositivity checks) for our implementation scales well with the matrix size, growing roughly like O(d(2)) for d x d matrices. The method is implemented in Julia and available at https://github.com/rileybadenbroek/CopositiveAnalyticCenter.jl. Summary of Contribution: Completely positive matrices play an important role in operations research. They allow many NP-hard problems to be formulated as optimization problems over a proper cone, which enables them to benefit from the duality theory of convex programming. We propose an analytic center cutting plane method to determine whether a matrix is completely positive by solving an optimization problem over the copositive cone. In fact, we can use our method to solve any copositive optimization problem, provided we know the radius of a ball containing an optimal solution. We emphasize numerical performance and stability in developing this method. A software implementation in Julia is provided

Examining the Correlation between Excessive Recreational Smartphone Use and Academic Performance Outcomes

The purpose of this study is to ascertain whether excessive recreational smartphone use significantly affects students’ academic performance outcomes, study patterns, learning abilities and interactions with fellow students and faculty. Data was collected from 257 students attending a small community college in Bermuda to identify if there is a direct correlation between the grade point averages of participants and excessive recreational time spent on their smartphones. This study will also highlight creative technology-based learning platforms and productive strategies that can assist faculty with converting excessive recreational smartphone use into productive and engaging learning opportunities

From instability to volatility: Bermuda\u27s shift from tourism to international business dependency

Bermuda has relied on tourism as a primarily source of economic activity ever since the 1920s. At the close of 2003, the World Bank positioned this small country behind only Luxemburg and the United States as the third richest country in the world. However, by 1995 Britain\u27s oldest colony experienced an economic dependency shift from tourism to international business. This article examines how this shift has impacted on the residents of Bermuda, economically and socially and points out the dangers of relying too heavily on international business. The survey results implied that there was a significant difference in the perceptions of respondents employed in various industries concerning tourism being more important to Bermuda\u27s economy than international business. Also, the majority of respondents agreed that international business revenues were primarily responsible for Bermuda\u27s current economic prosperity, and that the domestic tourism industry will not be able to sustain Bermuda\u27s economy if international business revenues suddenly declined. Additionally, exponential forecasting techniques were applied to determine the short-term prospects for Bermuda\u27s principle industries. The results showed accelerated growth trends in the international business sector causing a \u27pull\u27 effect for supporting industries and heightened demand for specialized labour. Conversely, the domestic tourism industry outlook leading up to 2010 displayed a continued negative growth trend. Consequently, tourism related jobs were predicted to decline, creating a \u27drag\u27 effect for supporting industries. The article concludes by suggesting that a community-based approach to tourism, along with sustaining international business growth could be the key to Bermuda\u27s long-term economic future