Defect tolerance: fundamental limits and examples

This paper addresses the problem of adding redundancy to a collection of physical objects so that the overall system is more robust to failures. In contrast to its information counterpart, which can exploit parity to protect multiple information symbols from a single erasure, physical redundancy can only be realized through duplication and substitution of objects. We propose a bipartite graph model for designing defect-tolerant systems, in which the defective objects are replaced by the judiciously connected redundant objects. The fundamental limits of this model are characterized under various asymptotic settings and both asymptotic and finite-size systems that approach these limits are constructed. Among other results, we show that the simple modular redundancy is in general suboptimal. As we develop, this combinatorial problem of defect tolerant system design has a natural interpretation as one of graph coloring, and the analysis is significantly different from that traditionally used in information redundancy for error-control codes.©201

Implementation of postpartum intrauterine device (PPIUD) services across 10 districts in Malawi

BackgroundMalawi has a high maternal mortality and unmet need for family planning, which could be reduced by improving access to postpartum intrauterine device (PPIUD) insertion. Our objective is to describe the implementation of PPIUD services by 4 local organizations at 14 government health services across 10 districts in Malawi. MethodsThis program was a collaborative effort between the Malawi Ministry of Health’s Reproductive Health Directorate and 4 supporting organizations. Training, educational, and monitoring and evaluation materials for PPIUD insertion were developed between December 2013 and April 2014. Each organization was then responsible for PPIUD community sensitization, provider training, and tracking of PPIUD insertions (via PPIUD register books) at their targeted health facilities. Community sensitization activities included Open Day campaigns, which were organized by local leaders to sensitize their communities, and Population Weekends, which were organized by religious leaders to target their congregations.ResultsCommunity sensitization activities, provider trainings, and mentoring occurred from January 2014 to June 2015, and monitoring and evaluation continued until December 2016 at some sites. One national Radio Discussion Panel with religious leaders was broadcast, 20 Open Day campaigns and 2 Population Weekends were held, 429 providers were trained during 27 trainings, and 249 PPIUD insertions occurred.ConclusionsPPIUD can be safely offered in Malawi. However, the biggest challenge with program implementation was with encouraging providers to take the extra time and effort to insert an IUD within 48 hours of delivery. In addition, frequent rotation of trained labour ward staff to other clinical areas hindered the program’s sustainability since new trainings had to be held whenever staff members were rotated. Further research should be done to determine the best strategies to motivate busy providers to insert PPIUD, and PPIUD should be integrated into both medical and nursing curriculums to reduce the number of postgraduate trainings required to sustain PPIUD services

Shared Service in the Archives: The Johns Hopkins University First-generation Students Oral History Project

Archivists, like librarians, often provide service to users that is defined by the mission and the institutional context of their employer. University archivists are tasked with documenting the history of their institution, and in doing so, have historically focused much of their attention on the records of institutional offices. This practice leaves out the stories of students and other communities affected by the institution. As immersed as university archivists are in academic libraries and the infrastructure of the academy, activist archivists can still challenge the status quo through intentional collecting of what is neither de facto, nor traditional. As archivists at the Johns Hopkins University (JHU) in Baltimore, Maryland, we recognized the lack of student representation in our university archives and set out to fill these gaps in our collection.https://digitalcommons.chapman.edu/librarian_books/1005/thumbnail.jp

Role of Family, Culture, and Peers in the Success of First-Generation Cambodian American College Students

Cambodian American college students are often overlooked in academe because of the model minority myth. The stereotype overshadows the challenges and heterogeneity in the Asian American and Pacific Islander population. This exploratory study examined the experiences of 13 first-generation Cambodian American college students at a large, public institution in California. Findings revealed that, despite obstacles of being first-generation with limited cultural capital, students were transformed into successful leaners when they received validation from their parents and peers and felt a sense of belonging to the college community through their involvement in an ethnic-based student organization

Spectrum of malignancies among the population of adults living with HIV infection in China: A nationwide follow-up study, 2008-2011.

BackgroundAlthough increasingly studied in high-income countries, there is a paucity of data from the Chinese population on the patterns of cancer among people living with HIV (PLHIV).MethodsWe conducted a nationwide follow-up study using routinely collected data for adult PLHIV diagnosed on or before 31 December 2011 and alive and in care as of 1 January 2008. Participants were observed from 1 January 2008 (study start) to 30 June 2012 (study end). Main outcome measures were gender-stratified age-standardized incidence rates for China (ASIRC) and standardized incidence ratios (SIR) for all malignancy types/sites observed.ResultsAmong 399,451 subjects, a majority was aged 30-44 years (49.3%), male (69.8%), and Han Chinese (67.9%). A total of 3,819 reports of cancer were identified. Overall, ASIRC was 776.4 per 100,000 for males and 486.5 per 100,000 for females. Malignancy sites/types with highest ASIRC among males were lung (226.0 per 100,000), liver (145.7 per 100,000), and lymphoma (63.1 per 100,000), and among females were lung (66.8 per 100,000), lymphoma (48.0 per 100,000), stomach (47.8 per 100,000), and cervix (47.6 per 100,000). Overall SIR for males was 3.4 and for females was 2.6. Highest SIR was observed for Kaposi sarcoma (2,639.8 for males, 1,593.5 for females) and lymphoma (13.9 for males, 16.0 for females).ConclusionsThese results provide evidence of substantial AIDS-defining and non-AIDS-defining cancer burden among adult Chinese PLHIV between 2008 and 2011. Although further study is warranted, China should take action to improve cancer screening, diagnosis, and treatment for this vulnerable population

Stochastic Opinion Dynamics under Social Pressure in Arbitrary Networks

Social pressure is a key factor affecting the evolution of opinions on networks in many types of settings, pushing people to conform to their neighbors' opinions. To study this, the interacting Polya urn model was introduced by Jadbabaie et al., in which each agent has two kinds of opinion: inherent beliefs, which are hidden from the other agents and fixed; and declared opinions, which are randomly sampled at each step from a distribution which depends on the agent's inherent belief and her neighbors' past declared opinions (the social pressure component), and which is then communicated to their neighbors. Each agent also has a bias parameter denoting her level of resistance to social pressure. At every step, the agents simultaneously update their declared opinions according to their neighbors' aggregate past declared opinions, their inherent beliefs, and their bias parameters. We study the asymptotic behavior of this opinion dynamics model and show that agents' declaration probabilities converge almost surely in the limit using Lyapunov theory and stochastic approximation techniques. We also derive necessary and sufficient conditions for the agents to approach consensus on their declared opinions. Our work provides further insight into the difficulty of inferring the inherent beliefs of agents when they are under social pressure

Denoising Particle-In-Cell Data via Smoothness-Increasing Accuracy-Conserving Filters with Application to Bohm Speed Computation

The simulation of plasma physics is computationally expensive because the underlying physical system is of high dimensions, requiring three spatial dimensions and three velocity dimensions. One popular numerical approach is Particle-In-Cell (PIC) methods owing to its ease of implementation and favorable scalability in high-dimensional problems. An unfortunate drawback of the method is the introduction of statistical noise resulting from the use of finitely many particles. In this paper we examine the application of the Smoothness-Increasing Accuracy-Conserving (SIAC) family of convolution kernel filters as denoisers for moment data arising from PIC simulations. We show that SIAC filtering is a promising tool to denoise PIC data in the physical space as well as capture the appropriate scales in the Fourier space. Furthermore, we demonstrate how the application of the SIAC technique reduces the amount of information necessary in the computation of quantities of interest in plasma physics such as the Bohm speed