Qualitative Case Studies in Operations Management: Trends, Research Outcomes, And Future Research Implications

Our study examines the state of qualitative case studies in operations management. Five main operations management journals are included for their impact on the field. They are in alphabetical order: Decision Sciences, International Journal of Operations and Production Management, Journal of Operations Management, Management Science, and Production and Operations Management. The qualitative case studies chosen were published between 1992 and 2007. With an increasing trend toward using more qualitative case studies, there have been meaningful and significant contributions to the field of operations management, especially in the area of theory building. However, in many of the qualitative case studies we reviewed, sufficient details in research design, data collection, and data analysis were missing. For instance, there are studies that do not offer sampling logic or a description of the analysis through which research out-comes are drawn. Further, research protocols for doing inductive case studies are much better developed compared to the research protocols for doing deductive case studies. Consequently, there is a lack of consistency in the way the case method has been applied. As qualitative researchers, we offer suggestions on how we can improve on what we have done and elevate the level of rigor and consistency

Affine maps of density matrices

For quantum systems described by finite matrices, linear and affine maps of matrices are shown to provide equivalent descriptions of evolution of density matrices for a subsystem caused by unitary Hamiltonian evolution in a larger system; an affine map can be replaced by a linear map, and a linear map can be replaced by an affine map. There may be significant advantage in using an affine map. The linear map is generally not completely positive, but the linear part of an equivalent affine map can be chosen to be completely positive and related in the simplest possible way to the unitary Hamiltonian evolution in the larger system.Comment: 4 pages, title changed, sentence added, reference update

Christianity and Capitalism: An Uneasy Coexistence

Throughout my research over the past year, I have noticed a grave opposition between the principles of capitalism and the values of Christianity. The two have seemed irreconcilable in my mind. Thus, using exegesis of passages from the Gospels of Matthew, Luke, and John, Acts, and some letters of Paul, as well as various texts we have read for the class, I claim that the Christian Truth is anti-wealth, anti-accumulation, and thus firmly anti-capitalist. Furthermore, I have found that the Christian Truth is an empowerment of the poor, it is egalitarian, and it opposes private property. Moreover, I explore and define this Truth and find Scriptural evidence for its existence. Furthermore, I discuss why it is imperative to follow this Truth in order to be a truly faithful subject of Christianity. Complementing that, I also elicit the evils of late capitalism and discuss the core teachings of Jesus Christ with which capitalism is in conflict. Finally, I propose actions for the individual Christian living in capitalist society to take, namely, joining a commune and perhaps giving up eating meat. I conclude that those two actions, if undertaken by enough people, would create a strong force in direct opposition to capitalist industry and its social structure, and help to create the conditions for the emergence of a genuine Christianity and the possible end of capitalism.https://orb.binghamton.edu/research_days_posters_2022/1139/thumbnail.jp

Performance Analysis of Channel Extrapolation in FDD Massive MIMO Systems

Channel estimation for the downlink of frequency division duplex (FDD) massive MIMO systems is well known to generate a large overhead as the amount of training generally scales with the number of transmit antennas in a MIMO system. In this paper, we consider the solution of extrapolating the channel frequency response from uplink pilot estimates to the downlink frequency band, which completely removes the training overhead. We first show that conventional estimators fail to achieve reasonable accuracy. We propose instead to use high-resolution channel estimation. We derive theoretical lower bounds (LB) for the mean squared error (MSE) of the extrapolated channel. Assuming that the paths are well separated, the LB is simplified in an expression that gives considerable physical insight. It is then shown that the MSE is inversely proportional to the number of receive antennas while the extrapolation performance penalty scales with the square of the ratio of the frequency offset and the training bandwidth. The channel extrapolation performance is validated through numeric simulations and experimental measurements taken in an anechoic chamber. Our main conclusion is that channel extrapolation is a viable solution for FDD massive MIMO systems if accurate system calibration is performed and favorable propagation conditions are present.Comment: arXiv admin note: substantial text overlap with arXiv:1902.0684

Independent Verification and Validation of the Hazardous Material Cost Trade-off Analysis Tool Developed by the Human Systems Center at Brooks Air Force Base

The Air Force realizes that the life cycle cost (LCC) associated with hazardous materials is a significant cost in the acquisition of major weapon systems. In trying to mitigate the growth of environmental LCC for future weapon systems, the Air Force has developed a tool called the Hazardous Material Cost Trade-off Analysis Tool (HAZMAT CTAT). The HAZMAT CTAT estimates the LCC for weapon system hazardous materials, so that intelligent decisions can be made in the early stages of the acquisition process. The problem with implementing this program into the acquisition process is that an independent computer model evaluation has never been conducted on the HAZMAT CTAT program. This thesis contains a rigorous computer model evaluation of the HAZMAT CTAT. The evaluation includes a computer model verification study using Decision Program Language (DPL) to verify if the HAZMAT CTAT model and an operational validation study using C-17 historical data to test if the HAZMAT CTAT accurately predicts actual costs

On the Finite-Time Blowup of a 1D Model for the 3D Axisymmetric Euler Equations

In connection with the recent proposal for possible singularity formation at the boundary for solutions of 3d axi-symmetric incompressible Euler's equations (Luo and Hou, 2013), we study models for the dynamics at the boundary and show that they exhibit a finite-time blow-up from smooth data.Comment: A paragraph at the end of Section 2 and an appendix discussing kinetic energy conservation are adde

The Effect of Carbon Payments on Deforestation Rates and Carbon Sequestration: Estimates from a Global Forestry and Agricultural Model.

Environmental Economics and Policy,

Effects of Lepton Flavour Violation on Chargino Production at the Linear Collider

We study the effects of lepton flavour violation (LFV) on the production processes e+e- --> \chi+_i \chi-_j at a linear collider with longitudinal e+ and e- beam polarizations. In the case of LFV the sneutrino mass eigenstates have no definite flavour, therefore, in the t-channel more than one sneutrino mass eigenstate can contribute to the chargino production cross sections. Our framework is the Minimal Supersymmetric Standard Model (MSSM) including LFV terms. We show that in spite of the restrictions on the LFV parameters due to the current limits on rare lepton decays, the cross section \sigma(e+e- --> \chi+_1 \chi-_1) can change by a factor of 2 or more when varying the LFV mixing angles. We point out that even if the present bound on BR(tau- --> e- gamma) improves by a factor of thousand the influence of LFV on the chargino production cross section can be significant. These results could have an important impact on the strategies for determining the underlying model parameters at the linear collider.Comment: 11pp; final version for JHE

Coherent many-body spin dynamics in a long-range interacting Ising chain

Coherent many-body quantum dynamics lies at the heart of quantum simulation and quantum computation. Both require coherent evolution in the exponentially large Hilbert space of an interacting many-body system. To date, trapped ions have defined the state of the art in terms of achievable coherence times in interacting spin chains. Here, we establish an alternative platform by reporting on the observation of coherent, fully interaction-driven quantum revivals of the magnetization in Rydberg-dressed Ising spin chains of atoms trapped in an optical lattice. We identify partial many-body revivals at up to about ten times the characteristic time scale set by the interactions. At the same time, single-site-resolved correlation measurements link the magnetization dynamics with inter-spin correlations appearing at different distances during the evolution. These results mark an enabling step towards the implementation of Rydberg atom based quantum annealers, quantum simulations of higher dimensional complex magnetic Hamiltonians, and itinerant long-range interacting quantum matter.Comment: 11 pages, 9 figure