Alternating Projections and Douglas-Rachford for Sparse Affine Feasibility

The problem of finding a vector with the fewest nonzero elements that satisfies an underdetermined system of linear equations is an NP-complete problem that is typically solved numerically via convex heuristics or nicely-behaved nonconvex relaxations. In this work we consider elementary methods based on projections for solving a sparse feasibility problem without employing convex heuristics. In a recent paper Bauschke, Luke, Phan and Wang (2014) showed that, locally, the fundamental method of alternating projections must converge linearly to a solution to the sparse feasibility problem with an affine constraint. In this paper we apply different analytical tools that allow us to show global linear convergence of alternating projections under familiar constraint qualifications. These analytical tools can also be applied to other algorithms. This is demonstrated with the prominent Douglas-Rachford algorithm where we establish local linear convergence of this method applied to the sparse affine feasibility problem.Comment: 29 pages, 2 figures, 37 references. Much expanded version from last submission. Title changed to reflect new development

Sediment Provenance Study of the Lower Hamilton Group: An Analysis of the Organic-Rich Facies and its Depositional History

Currently, insufficient geological models exist to explain the variability and distribution of TOC in the Marcellus Shale, within the Hamilton Group. TOC is one of the several limiting factors for natural gas production within the Marcellus Shale basin. One possible explanation for the low TOC regions is that detrital dilution was variable across the basin, with different sediment sources contributing detritus to low TOC areas, compared to surrounding regions with higher TOC. This hypothesis is tested by analyzing the source composition of inorganic detritus, using elemental and mineralogical proxies, with two cores in the Hamilton Group. The Armstrong #1 core is located in Taylor County, West Virginia and the Coldstream Affiliates 1MH (CSA) core is located in Clearfield County, Pennsylvania. Both these wells are located outside of the higher productivity regions with a nearby horizontal Armstrong well totaling 0.45 BCF/1000ft lateral and a nearby horizontal CSA well totaling 0.41 BCF/1000ft lateral. Variation in production may also result from over maturation of the kerogen-hosted pores. To evaluate the influence of thermal history, the thermal maturity of the Marcellus Shale in the lower productivity Armstrong #1 and CSA wells and the higher productivity MSEEL well was assessed using Raman spectroscopy. Major element, trace element, and REE geochemistry indicate the sediment source area was composed of intermediate and felsic granitic and recycled sedimentary lithologies. Samarium-neodymium isotopic analysis reveals a range of �DM ages and εNd values. The Armstrong #1 well �DM / εNd ranged from 1.64 to 1.91 Ga / -11.93 to -9.56 and the CSA from 1.62 to 1.88 Ga / -12.07 to -11.12. The εNd values became more negative upsection, however the �DM did not display a consistent trend relative to depth. Provenance analysis indicates the most likely source of clastic sediment was the Acadian Fold-Thrust Belt to the east with minor inputs from Superior Craton and southern Canadian Grenville Province. Ultimately, results conclude that elevated TOC was associated with only older �DM ages and recycled sedimentary signatures

Multi-state models for the analysis of Wheeze in a birth cohort of Western Cape children

Introduction Wheezing is common in young children. By the age of six, approximately 50% of children in high-income countries will have experienced at least one episode of wheezing in their life. Furthermore, childhood wheezing may be associated with reduced lung function and increased risk of asthma in later life. Determining the epidemiology of wheeze is complex given that the risk factors vary based on the age of the child and the phenotype of wheeze. Little is known regarding the recurrent nature of childhood wheezing in low- and middle-income contexts. This study aimed to use multi-state models to estimate the rate of transition among various states of wheeze in children from birth to the age of three years. This study also aimed to investigate the association between possible risk factors for childhood wheezing and the estimated transition intensities. Methods The rationale for conducting the study, as well as the objectives of the study, methods and data analysis plan are outlined in the study protocol (Part A). A summary of what is currently known about childhood wheezing is presented as part of the literature review (Part B). The aim of the literature review was to identify known risk factors for childhood wheeze and the methods used to analyse recurrent childhood wheezing, as well as identify the limitations of the current methods used to analyse recurrent childhood wheezing. A manuscript presenting the results of the study is included as Part C. This study was a secondary analysis of data from 1086 children from birth to three years, born to mothers in the Drakenstein area of the Western Cape, South Africa, enrolled at one of two pri- mary care clinics. The data were collected as part of a prospective birth cohort, the Drakenstein Child Health Study. Cox proportional hazards models were used to investigate the association of risk factors with time to first wheezing event and time to recurrent wheezing. Two multistate models investigating the progression of childhood wheezing were constructed. Multiple definitions of childhood wheeze as an outcome were investigated for all constructed models. A simple unidirectional multi-state model and a complex multi-state model with three states (never wheeze, wheeze not associated with lower respiratory tract infection (LRTI), and, lower respiratory tract infection associated wheeze) were constructed. The multi-state model allowed four possible transitions: 1) from “never wheeze” to “wheeze not associated with LRTI” or from 2) “never wheeze” to “LRTI-associated wheeze” or from 3) “wheeze not associated with LRTI” to “LRTI-associated wheeze” and from 4) “LRTI-associated wheeze” to “wheeze not associated with LRTI”. Transition intensities between wheeze states were estimated using discrete time multi-state models. The association of risk factors with transition intensities were estimated using multivariable proportional hazards models. Results Of the 1086 children included in the study, 476 (44%) experienced at least one episode of wheezing, and 227 (21%) experienced more than one episode of wheezing in the first three years of life. A total of 951 episodes of wheezing were recorded in the 36 months of follow-up time. In the multi-state analysis, LRTI-associated wheeze and wheeze not associated with LRTI were equally likely to be the first wheeze event. However, recurrent wheezing events were more likely to follow LRTI-associated wheeze as the first event (0.0020033 vs 8.6683754 × 10−4 ). Male children were at significantly higher risk of experiencing wheeze associated with an LRTI as the first wheezing event and at significantly higher risk of subsequent recurrent wheezing. Children exposed to maternal smoking prenatally had a significantly higher risk of transition to the wheeze state compared to unexposed children. Conclusion Multi-state models provide a novel method for the analysis of wheezing and recurrent wheezing in a cohort of children in South Africa. Multi-state models successfully predicted the progression of children through discrete states of wheeze and produced results consistent with existing literature on childhood wheeze, while accounting for recurrent events and interval-censored data

Hierarchical Losses and New Resources for Fine-grained Entity Typing and Linking

Extraction from raw text to a knowledge base of entities and fine-grained types is often cast as prediction into a flat set of entity and type labels, neglecting the rich hierarchies over types and entities contained in curated ontologies. Previous attempts to incorporate hierarchical structure have yielded little benefit and are restricted to shallow ontologies. This paper presents new methods using real and complex bilinear mappings for integrating hierarchical information, yielding substantial improvement over flat predictions in entity linking and fine-grained entity typing, and achieving new state-of-the-art results for end-to-end models on the benchmark FIGER dataset. We also present two new human-annotated datasets containing wide and deep hierarchies which we will release to the community to encourage further research in this direction: MedMentions, a collection of PubMed abstracts in which 246k mentions have been mapped to the massive UMLS ontology; and TypeNet, which aligns Freebase types with the WordNet hierarchy to obtain nearly 2k entity types. In experiments on all three datasets we show substantial gains from hierarchy-aware training.Comment: ACL 201

An Examination of Various Dimensions Associated with Nonprofit Board Member Diversity: The Significance of Organizational Factors

This dissertation examined how leadership and organizational factors influence nonprofit board diversity. The goal of the research was to expand the data available in the social service sector associated with understanding the role of board member diversity within nonprofit organizations. Utilizing data from BoardSource’s Leading with Intent (2017) dataset, which included responses from 1,378 nonprofit Chief Executive Officers (CEOs), board racial, gender, and total diversity, along with several organizational factors, were included for descriptive and inferential analysis. Organizational factors included CEO racial and gender demographics, organization type, geographical location, revenue, personal contribution of board members, CEO perception of mission and board diversity. Quantitative analysis included the use of ANOVAs, chi-squares, and logistic regressions to explore the relationships that existed between organizational characteristics and board racial, gender, and total diversity. Findings identified that significant positive relationships existed between racially diverse boards and CEO perception of board diversity and organizational mission, organizations with revenues of $1 million to$4.9 million and $million to$9.9 million, and organizations with women CEOs. Significant positive relationships were also noted between organizations with women CEOs and board gender and total diversity. Significant negative relationships were noted between board racial diversity and organizations that are foundations, organizations that require a personal contribution of board members, and non-White CEOs. Implications included review of organizational theories, board governance theories, and social justice theories, as well as for social work practice and social work education

Geoid Modelling in the Sultanate of Oman

This thesis covers the process taken to complete the Oman National Geoid Model project for the Sultanate of Oman. The steps taken to repair poor quality and badly referenced gravity data are explained. Each observation point was assigned a new orthometric height and its observed gravity was inversely calculated. The major biases that existed in the ground dataset were fixed using airborne free air anomalies at altitude. The ground data was merged with downward continued airborne gravity which was used to calculate the gravimetric geoid using the remove-compute-restore method. The remove step was completed using the residual terrain model modelling technique to calculate the quasigeoid. The gravimetric geoid was computed by adding the N- separation term to the quasigeoid and was fitted to the GPS-on-benchmarks provided by Oman. The external accuracy of the computed gravimetric geoid is 14 cm below mean sea level with a standard deviation of 30 cm

Home Ranch - A Single Family Residential Development in Gilroy, CA

Project Overview The purpose of this project was to provide a housing development plan for an undeveloped plot in the South Gilroy area. Project Statement The City of Gilroy needs additional housing to support the growth of their community. This project seeks to determine the best use of the undeveloped McCutchin Creek subplot and design its site layout. This plot of land is constrained by the City development codes, the 2023 City of Gilroy housing element, and the site specific development code. The deliverables presented to the client are a grading plan, site layout plan, stormwater and sewage plan, potable water, traffic assessment of development, and cost benefit analysis for the City

Nanoscale electrochemical movies and synchronous topographical mapping of electrocatalytic materials

Techniques in the scanning electrochemical probe microscopy (SEPM) family have shown great promise for resolving nanoscale structure–function (e.g., catalytic activity) at complex (electro)chemical interfaces, which is a long-term aspiration in (electro)materials science. In this work, we explore how a simple meniscus imaging probe, based on an easily-fabricated, single-channeled nanopipette (inner diameter ≈ 30 nm) can be deployed in the scanning electrochemical cell microscopy (SECCM) platform as a fast, versatile and robust method for the direct, synchronous electrochemical/topographical imaging of electrocatalytic materials at the nanoscale. Topographical and voltammetric data are acquired synchronously at a spatial resolution of 50 nm to construct maps that resolve particular surface features on the sub-10 nm scale and create electrochemical activity movies composed of hundreds of potential-resolved images on the minutes timescale. Using the hydrogen evolution reaction (HER) at molybdenite (MoS2) as an exemplar system, the experimental parameters critical to achieving a robust scanning protocol (e.g., approach voltage, reference potential calibration) with high resolution (e.g., hopping distance) and optimal scan times (e.g., voltammetric scan rate, approach rate etc.) are considered and discussed. Furthermore, sub-nanoentity reactivity mapping is demonstrated with glassy carbon (GC) supported single-crystalline {111}-oriented two-dimensional Au nanocrystals (AuNCs), which exhibit uniform catalytic activity at the single-entity and sub-single entity level. The approach outlined herein signposts a future in (electro)materials science in which the activity of electroactive nanomaterials can be viewed directly and related to structure through electrochemical movies, revealing active sites unambiguously