Shifting the Burden of HIV/AIDS

As the economic burden of HIV/AIDS increases in sub-Saharan Africa, the allocation of the burden among levels and sectors of societies is changing. The private sector has greater scope than government, households, or NGOs to avoid the economic burden of AIDS, and a systematic shifting of the burden away from the private sector is underway. Common practices that shift the AIDS burden from businesses to households and government include pre-employment screening, reduced employee benefits, restructured employment contracts, outsourcing of less skilled jobs, selective retrenchments, and changes in production technologies. In South Africa, more than two thirds of large employers have reduced health care benefits or required larger contributions by employees. Most firms have replaced defined benefit retirement funds, which expose the firm to large annual costs but provide long-term support for families, with defined contribution funds, which eliminate firm risk but provide little to families of younger workers who die of AIDS. Contracting out of previously permanent jobs also shields firms from costs while leaving households and government to care for affected workers and their families. Many of these changes are responses to globalization and would have occurred in the absence of AIDS, but they are devastating for employees with HIV/AIDS. This paper argues that the shifting of the economic burden of AIDS is a predictable response by business to which a thoughtful public policy response is needed. Countries should make explicit decisions about each sector’s responsibilities if a socially desirable allocation is to be achieved.

A Catechumenate for the Korean Methodist Church: Ressourcement, Formation and a Response to Secularism and Korean Traditional Religions

Research by Korean sociologists of religion indicates that Korean Protestantism has lost much of the spiritual vitality of preceding generations and that it increasingly shows the influences of Korean shamanism, Neo-Confucianism, and Western secularism and consumerism. Suggestions in the areas of homiletics and Christian social ethics have been offered to help steer the Korean Protestant churches away from these worldviews toward a more biblically-based course. Drawing upon and expanding these earlier studies and proposals, the current work recommends another method for developing a biblically-based, spiritually-revitalized, baptismally-shaped and ministry-committed Protestantism in Korea: a pre-baptismal adult catechumenate, in this case one designed for the context of the Korean Methodist Church. In order to produce a renewed catechumenal structure for Korean Methodism, adult catechumenal processes as well as baptismal theologies and rites are examined and analyzed from three principal sources: the first five centuries of the Christian church, and especially the mystagogical literature of the fourth century; the Roman Catholic Rite of Christian Initiation of Adults developed after the Second Vatican Council; and the United Methodist Church in the United States, both texts officially authorized by the denomination's General Conference and unofficial materials, among them resources for an adult catechumenate in the Come to the Waters series. In addition, previous and current practices of preparation for baptism in the Korean Methodist Church are identified and critiqued. From these findings a set of principles is put forward that guide the proposed catechumenal structure.

SOUND PROPAGATION AND SCATTERING IN BUBBLY LIQUIDS

In the ocean, natural and artificial processes generate clouds of bubbles which scatter and attenuate sound. Measurements have shown that at the individual bubble resonance frequency, sound propagation in this medium is highly attenuated and dispersive. Theory to explain this behavior exists in the literature, and is adequate away from resonance. However, due to excessive attenuation near resonance, little experimental data exists for comparison. An impedance tube was developed specifically for exploring this regime. Using the instrument, unique phase speed and attenuation measurements were made for void fractions ranging from 6.2 × 10^−5 to 2.7 × 10^−3 and bubble sizes centered around 0.62 mm in radius. Improved measurement speed, accuracy and precision is possible with the new instrument, and both instantaneous and time-averaged measurements were obtained. Behavior at resonance was observed to be sensitive to the bubble population statistics and agreed with existing theory, within the uncertainty of the bubble population parameters. Scattering from acoustically compact bubble clouds can be predicted from classical scattering theory by using an effective medium description of the bubbly fluid interior. Experimental verification was previously obtained up to the lowest resonance frequency. A novel bubble production technique has been employed to obtain unique scattering measurements with a bubbly-liquid-filled latex tube in a large indoor tank. The effective scattering model described these measurements up to three times the lowest resonance frequency of the structure.

Indexing Distances in Large Graphs and Applications in Search Tasks

This thesis elaborates on the problem of preprocessing a large graph so that single-pair shortest-path queries can be answered quickly at runtime. Computing shortest paths is a well studied problem, but exact algorithms do not scale well to real-world huge graphs in applications that require very short response time. The focus is on approximate methods for distance estimation, in particular in landmarks-based distance indexing. This approach involves choosing some nodes as landmarks and computing (offline), for each node in the graph its embedding, i.e., the vector of its distances from all the landmarks. At runtime, when the distance between a pair of nodes is queried, it can be quickly estimated by combining the embeddings of the two nodes. Choosing optimal landmarks is shown to be hard and thus heuristic solutions are employed. Given a budget of memory for the index, which translates directly into a budget of landmarks, different landmark selection strategies can yield dramatically different results in terms of accuracy. A number of simple methods that scale well to large graphs are therefore developed and experimentally compared. The simplest methods choose central nodes of the graph, while the more elaborate ones select central nodes that are also far away from one another. The efficiency of the techniques presented in this thesis is tested experimentally using five different real world graphs with millions of edges; for a given accuracy, they require as much as 250 times less space than the current approach which considers selecting landmarks at random. Finally, they are applied in two important problems arising naturally in large-scale graphs, namely social search and community detection.

Fast Shortest Path Distance Estimation in Large Networks

We study the problem of preprocessing a large graph so that point-to-point shortest-path queries can be answered very fast. Computing shortest paths is a well studied problem, but exact algorithms do not scale to huge graphs encountered on the web, social networks, and other applications. In this paper we focus on approximate methods for distance estimation, in particular using landmark-based distance indexing. This approach involves selecting a subset of nodes as landmarks and computing (offline) the distances from each node in the graph to those landmarks. At runtime, when the distance between a pair of nodes is needed, we can estimate it quickly by combining the precomputed distances of the two nodes to the landmarks. We prove that selecting the optimal set of landmarks is an NP-hard problem, and thus heuristic solutions need to be employed. Given a budget of memory for the index, which translates directly into a budget of landmarks, different landmark selection strategies can yield dramatically different results in terms of accuracy. A number of simple methods that scale well to large graphs are therefore developed and experimentally compared. The simplest methods choose central nodes of the graph, while the more elaborate ones select central nodes that are also far away from one another. The efficiency of the suggested techniques is tested experimentally using five different real world graphs with millions of edges; for a given accuracy, they require as much as 250 times less space than the current approach in the literature which considers selecting landmarks at random. Finally, we study applications of our method in two problems arising naturally in large-scale networks, namely, social search and community detection.

Biased ART: A Neural Architecture that Shifts Attention Toward Previously Disregarded Features Following an Incorrect Prediction

Memories in Adaptive Resonance Theory (ART) networks are based on matched patterns that focus attention on those portions of bottom-up inputs that match active top-down expectations. While this learning strategy has proved successful for both brain models and applications, computational examples show that attention to early critical features may later distort memory representations during online fast learning. For supervised learning, biased ARTMAP (bARTMAP) solves the problem of over-emphasis on early critical features by directing attention away from previously attended features after the system makes a predictive error. Small-scale, hand-computed analog and binary examples illustrate key model dynamics. Twodimensional simulation examples demonstrate the evolution of bARTMAP memories as they are learned online. Benchmark simulations show that featural biasing also improves performance on large-scale examples. One example, which predicts movie genres and is based, in part, on the Netflix Prize database, was developed for this project. Both first principles and consistent performance improvements on all simulation studies suggest that featural biasing should be incorporated by default in all ARTMAP systems. Benchmark datasets and bARTMAP code are available from the CNS Technology Lab Website: http://techlab.bu.edu/bART/.