Partial Coherence Estimation via Spectral Matrix Shrinkage under Quadratic Loss

Partial coherence is an important quantity derived from spectral or precision matrices and is used in seismology, meteorology, oceanography, neuroscience and elsewhere. If the number of complex degrees of freedom only slightly exceeds the dimension of the multivariate stationary time series, spectral matrices are poorly conditioned and shrinkage techniques suggest themselves. When true partial coherencies are quite large then for shrinkage estimators of the diagonal weighting kind it is shown empirically that the minimization of risk using quadratic loss (QL) leads to oracle partial coherence estimators superior to those derived by minimizing risk using Hilbert-Schmidt (HS) loss. When true partial coherencies are small the methods behave similarly. We derive two new QL estimators for spectral matrices, and new QL and HS estimators for precision matrices. In addition for the full estimation (non-oracle) case where certain trace expressions must also be estimated, we examine the behaviour of three different QL estimators, the precision matrix one seeming particularly robust and reliable. For the empirical study we carry out exact simulations derived from real EEG data for two individuals, one having large, and the other small, partial coherencies. This ensures our study covers cases of real-world relevance

Proposed gravity-gradient dynamics experiments using the RAE-1 spacecraft

Gravity gradient dynamics experiments using Radio Astronomy Explorer Satellite in earth orbi

God, Mother and Island Creek : The Story of Holden Central School and the Emergence of Nurturing Paternalism

The story of the community of Holden, West Virginia (Logan County), Island Creek Coal Company, and its model school (Holden Central School) offers a counternarrative to the dominant deficit-oriented narratives concerning Appalachian education. In particular, the progressive nature of Island Creek Coal Company led it to create a model coal camp community and a school that educated their employees’ children. The school operated from 1922 until 1970, when the combined elementary and junior high school closed its doors forever. Island Creek Coal Company both designed, supplied, and oversaw the daily operations of a benevolent community with all the modern amenities of the day while paradoxically exercising strict, authoritative control of its mines. When it came to the Holden Central school, this conflicting behavior on the part of the coal company was perceived by former teachers and students as a positive, albeit contradictory “nurturing paternalistic” force of influence, rather than a manipulative force of exploitation. This study explores the complex dynamics of these relationships in an effort to construct a narrative for the larger story of Holden as a community, a school, and the headquarters of a powerful coal company. This was accomplished by combining the analyses of archival records and newspaper articles, along with oral histories of former educators and students from Holden Central School. This collaborative ethnographic research complicates larger, dominant narratives and provides scholars of rural education and Appalachian Studies with a new lens to view company towns and the industries that ran them

Miners and Mentors: Memory and Experiences in Coal Camp Schools in Appalachia

Appalachian educational history is as diverse as its mountains and music. As the number of the living students and teachers who taught and learned in coal camp schools dwindle over the years, their memories and experiences will also fade with them, if not preserved for future generations. I interviewed my grandmother, who taught in a small, rural two-room schoolhouse during the 1947-1948 school year in order to acquire the perspective from a former teacher who taught in a learning environment similar to that of a coal camp school. I also interviewed Dr. Stan Maynard, who attended two coal camp schools between the years of 1948-1956. His interview allowed me to explore the perspective of a former student who attended a coal camp school. Over the course of recording and analyzing both interviews, there were five major themes that emerged. First there was a vivid description of the local community that surrounded the schools that my grandmother taught at and the ones that Dr. Maynard attended over the years. Second, there was a strong emphasis on the different curricula for the schools that were discussed in the interviews. Next the daily routine and structure of the school day was discussed, right before both interview subjects elaborated on the student-teacher relationships that were created in this caring mentor dynamic. Finally, the success and legacy of the coal camp school mentality was discussed in order to stress the importance of the impact that this kind of school environment had on both interview subjects