Collective Almost Synchronization in Complex Networks

This work introduces the phenomenon of Collective Almost Synchronization (CAS), which describes a universal way of how patterns can appear in complex networks even for small coupling strengths. The CAS phenomenon appears due to the existence of an approximately constant local mean field and is characterized by having nodes with trajectories evolving around periodic stable orbits. Common notion based on statistical knowledge would lead one to interpret the appearance of a local constant mean field as a consequence of the fact that the behavior of each node is not correlated to the behaviors of the others. Contrary to this common notion, we show that various well known weaker forms of synchronization (almost, time-lag, phase synchronization, and generalized synchronization) appear as a result of the onset of an almost constant local mean field. If the memory is formed in a brain by minimising the coupling strength among neurons and maximising the number of possible patterns, then the CAS phenomenon is a plausible explanation for it.Comment: 3 figure

Awareness, perceived risk and practices related to cervical cancer and Pap smear screening: A crosssectional study among HIV-positive women attending an urban HIV clinic in Johannesburg, South Africa

Background. Cervical cancer is a major cause of cancer-related deaths, especially in the context of the HIV epidemic.Objective. To examine awareness, perceived risk and practices related to cervical cancer screening among HIV-positive women.Methods. Interviewer-administered structured questionnaires were administered to HIV-positive women (aged ≥18 years) enrolled in a cervical cancer screening study at the Themba Lethu Clinic, Johannesburg, South Africa, from November 2009 to December 2011. Modified Poisson regression with robust standard errors was used to identify factors at enrolment associated with awareness, perceived risk and adequate practice related to cervical screening. Adjusted relative risks (aRRs) with 95% confidence intervals (CIs) are presented.Results. Of the 1 202 women enrolled, 71.3% and 18.2% were aware of the Pap smear and HPV, respectively. Of the 1 192 participants with data evaluated, 76.5% were worried and 23.5% were not worried about cervical cancer; 28.6% of the women had adequate screening practice. Older age (40 - 49 years or ≥50 years v. 18 - 29 years) (aRR 1.63, 95% CI 1.12 - 2.37; aRR 2.22, 95% CI 1.44 - 3.41), higher education (tertiary v. less than grade 10) (aRR 1.39, 95% CI 1.00 - 1.93), initiation on combination antiretroviral therapy (aRR 1.36, 95% CI 1.00 - 1.85) and awareness of Pap smear screening (aRR 16.18, 95% CI 7.69 - 34.01) were associated with adequate screening practice.Conclusions. High levels of Pap smear awareness and low levels of Pap smear screening uptake were observed. However, Pap smear awareness was associated with adequate screening practice. More research into effective health education programmes to address these gaps is needed

Bulk vacancies in CdxHg1–xTe

We report the first theoretical study of vacancies in CdxHg1–xTe alloys. The study employs the tight-binding method for obtaining the Hamiltonian. The Slater–Koster Green's function method is used to obtain the electronic states that result from removing a cation or anion from the virtual crystal used to model the alloys. The primary results are that the anion vacancy levels are far into the conduction band and hence are not likely to produce levels in the gap. In contrast, the cation vacancy is found to produce levels near the valence band edge. We find that spatially these states are very localized on the atoms nearest the vacancy

Parallel altitudinal clines reveal trends in adaptive evolution of genome size in \u3ci\u3eZea mays\u3c/i\u3e

While the vast majority of genome size variation in plants is due to differences in repetitive sequence, we know little about how selection acts on repeat content in natural populations. Here we investigate parallel changes in intraspecific genome size and repeat content of domesticated maize (Zea mays) landraces and their wild relative teosinte across altitudinal gradients in Mesoamerica and South America. We combine genotyping, low coverage whole-genome sequence data, and flow cytometry to test for evidence of selection on genome size and individual repeat abundance. We find that population structure alone cannot explain the observed variation, implying that clinal patterns of genome size are maintained by natural selection. Our modeling additionally provides evidence of selection on individual heterochromatic knob repeats, likely due to their large individual contribution to genome size. To better understand the phenotypes driving selection on genome size, we conducted a growth chamber experiment using a population of highland teosinte exhibiting extensive variation in genome size. We find weak support for a positive correlation between genome size and cell size, but stronger support for a negative correlation between genome size and the rate of cell production. Reanalyzing published data of cell counts in maize shoot apical meristems, we then identify a negative correlation between cell production rate and flowering time. Together, our data suggest a model in which variation in genome size is driven by natural selection on flowering time across altitudinal clines, connecting intraspecific variation in repetitive sequence to important differences in adaptive phenotypes

Prospective One Year follow up of HIV infected women screened for cervical cancer using visual inspection with acetic acid, cytology and human papillomavirus testing in Johannesburg, South Africa

BACKGROUND: Cervical cancer is the most common cancer in Sub-Saharan Africa. There are little of HIV-infected women one-year after screening using visual inspection with acetic acid (VIA), HPV or cytology in sub-Saharan Africa. METHODS: HIV-infected women in Johannesburg South Africa were screened one year later by Pap smear, VIA and human papillomavirus (HPV) testing. Women qualified for the 12 month follow-up visit if they had a negative or cervical intra-epithelial neoplasia (CIN) 1 results at the baseline visit. Modified Poisson regression was used to analyse associations between patient baseline characteristics and progression. RESULTS: A total of 688 of 1,202 enrolled at baseline study who were CIN-2+ negative and qualified for a 12 month follow-up visit. Progression to CIN-2+ was higher in women with positive VIA results (12.6%; 24/191) than those VIA-negative (4.4%; 19/432). HPV-positive women at baseline were more likely to progress to CIN-2+ (12.3%; 36/293) than those HPV-negative (2.1%; 7/329). Cytology-positive women at baseline were more likely to progress to CIN-2+ (9.6%; 37/384) than cytology-negative women (2.5%; 6/237). Approximately 10% (10.4%; 39/376) of women with CIN 1 at baseline progressed to CIN 2+. Women who were VIA or HPV positive at baseline were more likely to progress aIRR 1.85, CI 95% (1.46 to 2.36), aIRR 1.41 CI 95% (1.14 to 1.75) respectively. CONCLUSION: Progression to CIN-2+ in HIV-infected women is significant when measured by baseline positive VIA, HPV or Pap and yearly screening by any method should be considered in this population if possible

Systemic cost of risk for heavy haul operations in South Africa

Abstract: This paper compares the systemic cost of risk between the two heavy haul lines and general freight routes on the South African rail network to determine operational resilience of heavy haul rail systems in a growing export market. The Railway Safety Regulator in South Africa requires permitted railway operators to report extrinsic incidents and intrinsic occurrences in a standardised manner, as well as direct costs aggregated for combined categories. Data recorded and categorized since 2009 according to national standards provides insight into route-specific systemic cost of risk when related to the gross domestic product railed over time. The 33,079 intrinsic occurrences and extrinsic incidents were geospatially superimposed to the nearest station on an existing audited rail freight flow model for South Africa. Reported railway occurrence cost was allocated on an average basis to the nearest station associated with an incident or occurrence. A leading business intelligence tool was used to query the combined database. Data was visualized using maps, animations and graphs. Results suggest that over time the heavy haul remote western iron ore export line exhibits superior route-specific systemic cost of risk when compared to the more populous coal export line over difficult terrain in the east, and the various general freight lines. Evidence suggests that, in terms of systemic cost of risk, the heavy haul model is resilient in a growing market. The paper concludes that socioeconomic factors, topography, and railway operational considerations contribute to systemic cost of risk