Cohesion, Structure and Software Complexity: A Model of Open Source Software Development

As the use of open source software gains popularity, it is important to understand the factors that contribute to the success of open source software development projects. This research contributes to this understanding by developing a set of propositions about the organizational structure that supports open source software projects. We argue that in open source software development it is important to understand the existence and interaction of two related but distinct entities; the interest community and the software development group. We propose relationships between the development group, the interest community and software complexity in open source software development. Implications of the propositions for research and practice are discussed

Reporting of clinically diagnosed dementia on death certificates:retrospective cohort study

Background: mortality statistics are a frequently used source of information on deaths in dementia but are limited by concerns over accuracy. Objective: to investigate the frequency with which clinically diagnosed dementia is recorded on death certificates, including predictive factors. Methods: a retrospective cohort study assembled using a large mental healthcare database in South London, linked to Office for National Statistics mortality data. People with a clinical diagnosis of dementia, aged 65 or older, who died between 2006 and 2013 were included. The main outcome was death certificate recording of dementia. Results: in total, 7,115 people were identified. Dementia was recorded on 3,815 (53.6%) death certificates. Frequency of dementia recording increased from 39.9% (2006) to 63.0% (2013) (odds ratio (OR) per year increment 1.11, 95% CI 1.07–1.15). Recording of dementia was more likely if people were older (OR per year increment 1.02, 95% CI 1.01–1.03), and for those who died in care homes (OR 1.89, 95% CI 1.50–2.40) or hospitals (OR 1.14, 95% CI 1.03–1.46) compared with home, and less likely for people with less severe cognitive impairment (OR 0.95, 95% CI 0.94–0.96), and if the diagnosis was Lewy body (OR 0.30, 95% CI 0.15–0.62) or vascular dementia (OR 0.79, 95% CI 0.68–0.93) compared with Alzheimer's disease. Conclusions: changes in certification practices may have contributed to the rise in recorded prevalence of dementia from mortality data. However, mortality data still considerably underestimate the population burden of dementia. Potential biases affecting recording of dementia need to be taken into account when interpreting mortality data

Current HIV/AIDS end-of-life care in sub-Saharan Africa: a survey of models, services, challenges and priorities

BACKGROUND: In response to increased global public health funding initiatives to HIV/AIDS care in Africa, this study aimed to describe practice models, strategies and challenges to delivering end-of-life care in sub-Saharan Africa. METHODS: A survey end-of-life care programs was conducted, addressing the domains of service aims and configuration, barriers to pain control, governmental endorsement and strategies, funding, monitoring and evaluation, and research. Both closed and qualitative responses were sought. RESULTS: Despite great structural challenges, data from 48 programs in 14 countries with a mean annual funding of US $374,884 demonstrated integrated care delivery across diverse settings. Care was commonly integrated with all advanced disease care (67%) and disease stages (65% offering care from diagnosis). The majority (98%) provided home-based care for a mean of 301 patients. Ninety-four percent reported challenges in pain control (including availability, lack of trained providers, stigma and legal restrictions), and 77% addressed the effects of poverty on disease progression and management. Although 85% of programs reported Government endorsement, end-of-life and palliative care National strategies were largely absent. CONCLUSIONS: The interdependent tasks of expanding pain control, balancing quality and coverage of care, providing technical assistance in monitoring and evaluation, collaborating between donor agencies and governments, and educating policy makers and program directors of end-of-life care are all necessary if resources are to reach their goals

The Affordable Care Act: U.S. Vaccine Policy and Practice

When fully implemented, the Patient Protection and Affordable Care Act, amended by the Health and Education Reconciliation Act will extend health insurance coverage to 94 percent of Americans while establishing a comprehensive set of strategies to improve care and contain costs. The central provisions of the Act – guaranteed affordable and accessible coverage – take effect January 1, 2014. Important insurance reforms aimed at improving coverage become effective before that date, as do a series of investments aimed at improving the accessibility and quality of health care. This report has several aims: 1) to examine how the laws address vaccine policy and practice; 2) to assess how access to vaccines and immunization services will be affected; and 3) to assess the extent to which health reform addresses recommendations of the National Vaccine Advisory Committee\u27s (NVAC) Vaccine Finance Working Group (VFWG) 2008

A Test of the Standard Hypothesis for the Origin of the HI Holes in Holmberg II

The nearby irregular galaxy Holmberg II has been extensively mapped in HI using the Very Large Array (VLA), revealing intricate structure in its interstellar gas component (Puche et al. 1992). An analysis of these structures shows the neutral gas to contain a number of expanding HI holes. The formation of the HI holes has been attributed to multiple supernova events occurring within wind-blown shells around young, massive star clusters, with as many as 10-200 supernovae required to produce many of the holes. From the sizes and expansion velocities of the holes, Puche et al. assigned ages of ~10^7 to 10^8 years. If the supernova scenario for the formation of the HI holes is correct, it implies the existence of star clusters with a substantial population of late-B, A and F main sequence stars at the centers of the holes. Many of these clusters should be detectable in deep ground-based CCD images of the galaxy. In order to test the supernova hypothesis for the formation of the HI holes, we have obtained and analyzed deep broad-band BVR and narrow-band H-alpha images of Ho II. We compare the optical and HI data and search for evidence of the expected star clusters in and around the HI holes. We also use the HI data to constrain models of the expected remnant stellar population. We show that in several of the holes the observed upper limits for the remnant cluster brightness are strongly inconsistent with the SNe hypothesis described in Puche et al. Moreover, many of the HI holes are located in regions of very low optical surface brightness which show no indication of recent star formation. Here we present our findings and explore possible alternative explanations for the existence of the HI holes in Ho II, including the suggestion that some of the holes were produced by Gamma-ray burst events.Comment: 30 pages, including 6 tables and 3 images. To appear in Astron. Journal (June 1999

Evaluation of Doped and Undoped Poly (o-anisidine) as Sensing Materials for a Sensor Array for Volatile Organic Compounds

This is the peer reviewed version of the following article: Stewart, K. M. E., Scott, A. J., & Penlidis, A. (2020). Evaluation of doped and undoped poly (o-anisidine) as sensing materials for a sensor array for volatile organic compounds. Polymers for Advanced Technologies, 31(7), 1474–1483. https://doi.org/10.1002/pat.4877, which has been published in final form at https://doi.org/10.1002/pat.4877. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Poly (o-anisidine) (PoANI) and PoANI doped with nickel oxide and zinc oxide were evaluated as sensing materials for four gas analytes (methanol, ethanol, acetone, and benzene). The sensing materials had high sensitivity (showing an affinity towards the target analytes even at low concentrations, in the range of 1 ppm to 5 ppm), but rather poor selectivity, especially when the gas analytes were in a mixture. To exploit the poor selectivity, the three sensing materials were combined into a sensor array using principal component analysis (PCA) as a sensing algorithm. It was found that using a sensor array, the four individual gases could be separated. However, when all four gases were present (in analyte mixtures), there was too much overlap in the responses to distinguish between individual gas analytes and their related mixtures.The authors are grateful for financial support from the Natural Sciences and Engineering Research Council (NSERC) of Canada and the Canada Research Chair (CRC) program

Spectrum of antibacterial activity and mode of action of a novel tris-stilbene bacteriostatic compound

The spectrum of activity and mode of action of a novel antibacterial agent, 135C, was investigated using a range of microbiological and genomic approaches. Compound 135C was active against Gram-positive bacteria with MICs for Staphylococcus aureus ranging from 0.12-0.5 μg/ml. It was largely inactive against Gram-negative bacteria. The compound showed bacteriostatic activity in time-kill studies and did not elicit bacterial cell leakage or cell lysis. Checkerboard assays showed no synergy or antagonism when 135C was combined with a range of other antibacterials. Multi-step serial passage of four S. aureus isolates with increasing concentrations of 135C showed that resistance developed rapidly and was stable after drug-free passages. Minor differences in the fitness of 135C-resistant strains and parent wildtypes were evident by growth curves, but 135C-resistant strains did not show cross-resistance to other antibacterial agents. Genomic comparison of resistant and wildtype parent strains showed changes in genes encoding cell wall teichoic acids. 135C shows promising activity against Gram-positive bacteria but is currently limited by the rapid resistance development. Further studies are required to investigate the effects on cell wall teichoic acids and to determine whether the issue of resistance development can be overcome

Predicting Dispersal and Conflict Risk for Wolf Recolonization in Colorado

1. The colonization of suitable yet unoccupied habitat due to natural dispersal or human introduction can benefit recovery of threatened species. Predicting habitat suitability and conflict potential of colonization areas can facilitate conservation planning. 2. Planning for reintroduction of gray wolves (Canis lupus) to the United States state of Colorado is underway. Assessing which occupancy sites minimize the likelihood of human-wolf conflict during dispersal events and seasonal movements is critical to the success of this initiative. 3. We used a spatial absorbing Markov chain (SAMC) framework, which extends random walk theory and probabilistically accounts for both movement behavior and mortality risk, to compare the viability of potential occupancy sites (public lands \u3e 500 km2 to minimally meet wolf pack range area). The SAMC framework produced spatially explicit predictions of wolf dispersal, philopatry and conflict risk ahead of recolonization prior to reintroduction efforts. Our SAMC model included: (1) movement resistance based on terrain, roads and housing density; (2) mortality risk and potential conflict (absorption) based on livestock presence, social tolerance, land ownership and state boundaries; and (3) site fidelity based on habitat quality. Using this model, we compared 21 public land units by deriving predictions of: (A) relative survival time outside each site, (B) intensity of use and retention time within each site, and (C) the probability of use on adjacent public lands. We also predicted and mapped potential conflict hot spots associated with each site. 4. Among the units assessed, a complex of United States Forest Service Wilderness areas near Aspen, chiefly the Hunter-Fryingpan and Collegiate Peaks Wilderness areas, had the best overall rankings when comparing predictions of each metric. The area balances high-quality, well-connected habitat with relatively low livestock density and high social tolerance. 5. Synthesis and applications. Our findings highlight the utility of the SAMC framework for assessing colonization areas and the capacity to identify locations for effective proactive management, especially of conflict prone species. The flexibility of the SAMC framework enables predicting likely areas of philopatry and human-wildlife conflict using spatially explicit metrics which can improve the success of conservation translocations and management of species with changing geographic extents

"It's not like taking chocolates": factors influencing the feasibility and sustainability of universal test and treat in correctional health systems in Zambia and South Africa

Background: Sub-Saharan African correctional facilities concentrate large numbers of people who are living with HIV or at risk for HIV infection. Universal test and treat (UTT) is widely recognized as a promising approach to improve the health of individuals and a population health strategy to reduce new HIV infections. In this study, we explored the feasibility and sustainability of implementing UTT in correctional facilities in Zambia and South Africa. Methods: Nested within a UTT implementation research study, our qualitative evaluation of feasibility and sustainability used a case-comparison design based on data from 1 Zambian and 3 South African correctional facilities. Primary data from in-depth interviews with incarcerated individuals, correctional managers, health care providers, and policy makers were supplemented by public policy documents, study documentation, and implementation memos in both countries. Thematic analysis was informed by an empirically established conceptual framework for health system analysis. Results: Despite different institutional profiles, we were able to successfully introduce UTT in the South Africa and Zambian correctional facilities participating in the study. A supportive policy backdrop was important to UTT implementation and establishment in both countries. However, sustainability of UTT, defined as relevant government departments' capacity to independently plan, resource, and administer quality UTT, differed. South Africa's correctional facilities had existing systems to deliver and monitor chronic HIV care and treatment, forming a “scaffolding” for sustained UTT despite some human resources shortages and poorly integrated health information systems. Notwithstanding recent improvements, Zambia's correctional health system demonstrated insufficient material and technical capacity to independently deliver quality UTT. In the correctional facilities of both countries, inmate population dynamics and their impact on HIV-related stigma were important factors in UTT service uptake. Conclusion: Findings demonstrate the critical role of policy directives, health service delivery systems, adequate resourcing, and population dynamics on the feasibility and likely sustainability of UTT in corrections in Zambia and South Africa

Small contribution of gold mines to the ongoing tuberculosis epidemic in South Africa: a modeling-based study.

BACKGROUND: Gold mines represent a potential hotspot for Mycobacterium tuberculosis (Mtb) transmission and may be exacerbating the tuberculosis (TB) epidemic in South Africa. However, the presence of multiple factors complicates estimation of the mining contribution to the TB burden in South Africa. METHODS: We developed two models of TB in South Africa, a static risk model and an individual-based model that accounts for longer-term trends. Both models account for four populations - mine workers, peri-mining residents, labor-sending residents, and other residents of South Africa - including the size and prevalence of latent TB infection, active TB, and HIV of each population and mixing between populations. We calibrated to mine- and country-level data and used the static model to estimate force of infection (FOI) and new infections attributable to local residents in each community compared to other residents. Using the individual-based model, we simulated a counterfactual scenario to estimate the fraction of overall TB incidence in South Africa attributable to recent transmission in mines. RESULTS: We estimated that the majority of FOI in each community is attributable to local residents: 93.9% (95% confidence interval 92.4-95.1%), 91.5% (91.4-91.5%), and 94.7% (94.7-94.7%) in gold mining, peri-mining, and labor-sending communities, respectively. Assuming a higher rate of Mtb transmission in mines, 4.1% (2.6-5.8%), 5.0% (4.5-5.5%), and 9.0% (8.8-9.1%) of new infections in South Africa are attributable to gold mine workers, peri-mining residents, and labor-sending residents, respectively. Therefore, mine workers with TB disease, who constitute ~ 2.5% of the prevalent TB cases in South Africa, contribute 1.62 (1.04-2.30) times as many new infections as TB cases in South Africa on average. By modeling TB on a longer time scale, we estimate 63.0% (58.5-67.7%) of incident TB disease in gold mining communities to be attributable to recent transmission, of which 92.5% (92.1-92.9%) is attributable to local transmission. CONCLUSIONS: Gold mine workers are estimated to contribute a disproportionately large number of Mtb infections in South Africa on a per-capita basis. However, mine workers contribute only a small fraction of overall Mtb infections in South Africa. Our results suggest that curtailing transmission in mines may have limited impact at the country level, despite potentially significant impact at the mining level