482 research outputs found
Quantification of annual settlement growth in rural mining areas using machine learning
Studies on annual settlement growth have mainly focused on larger cities or incorporated data rarely available in, or applicable to, sparsely populated areas in sub-Saharan Africa, such as aerial photography or night-time light data. The aim of the present study is to quantify settlement growth in rural communities in Burkina Faso affected by industrial mining, which often experience substantial in-migration. A multi-annual training dataset was created using historic Google Earth imagery. Support vector machine classifiers were fitted on Landsat scenes to produce annual land use classification maps. Post-classification steps included visual quality assessments, majority voting of scenes of the same year and temporal consistency correction. Overall accuracy in the four studied scenes ranged between 58.5% and 95.1%. Arid conditions and limited availability of Google Earth imagery negatively affected classification accuracy. Humid study sites, where training data could be generated in proximity to the areas of interest, showed the highest classification accuracies. Overall, by relying solely on freely and globally available imagery, the proposed methodology is a promising approach for tracking fast-paced population dynamics in rural areas where population data is scarce. With the growing availability of longitudinal high-resolution imagery, including data from the Sentinel satellites, the potential applications of the methodology presented will further increase in the futur
Housing conditions and respiratory health in children in mining communities: an analysis of data from 27 countries in sub-Saharan Africa
Background Poor housing conditions, such as poor building materials and weak structures as well as high levels of indoor air pollution, are important risk factors for a broad range of diseases, including acute respiratory infections (ARI). In mining areas, research on the determinants of respiratory health predominantly focuses on exposures to outdoor air pollutants deriving from mining operations. However, mining projects also influence the socioeconomic status of households, which, in turn, affect housing quality and individual behaviors and, thus, housing quality and levels of indoor air pollution. In this study, we aimed to determine how proximity to an industrial mining project impacts housing quality, sources of indoor air pollution, and prevalence of ARI. Methods We merged data from 131 Demographic and Health Surveys (DHS) with georeferenced data on mining projects in sub-Saharan Africa (SSA) to determine associations between housing quality, indoor air pollution sources, and child respiratory health. Spatial differences in selected indicators were explored using descriptive cross-sectional analyses. Furthermore, we applied a quasi-experimental difference-in-differences (DiD) approach using generalized linear mixed-effects models to compare temporal changes in household and child health indicators at different operational phases of mining projects and as a function of distance to mines. Results For cross-sectional analyses, data of 183,466 households and 141,384 children from 27 countries in SSA were used, while 41,648 households and 34,406 children from 23 SSA countries were included in the DiD analyses. The increase in the share of houses being built from finished building materials after mine opening was more than 4-fold higher (odds ratio (OR): 4.32, 95% confidence interval (CI): 2.98-6.24) in close proximity to mining sites (i.e., ≤ 10 km) compared to areas further away (i.e., 10-50 km). However, these benefits were not equally distributed across socioeconomic strata, with considerably weaker effects observed among poorer households. Increases in indoor tobacco smoking rates in close proximity to operating mines were twice as high as in comparison areas (OR: 2.06, 95% CI: 1.15-3.68). The cross-sectional analyses revealed that traditional cooking fuels (e.g., charcoal, dung, and wood) were less frequently used (OR: 0.27, 95% CI: 0.23-0.31) in areas located in close proximity to mines than in comparison areas. Overall, no statistically significant association between mining operations and the prevalence of symptoms related to ARI in children under the age of 5 years was observed (OR: 0.78, 95% CI: 0.29-2.07). Conclusions Mines impact known risk factors for ARI through diverse pathways. The absence of significant changes in ARI symptoms among children is likely the result of counteracting effects between improvements in housing infrastructure and increased exposures to air pollutants from outdoor sources and tobacco smoking. For mining projects to unfold their full potential for community development, we recommend that impact assessments move beyond the mere appraisal of mining-related pollution emissions and try to include a more comprehensive set of pathways through which mines can affect ARI in exposed communities
Industrial development under institutional frailty: the development of the Mexican textile industry in the nineteenth century
La Historia Económica en Latinoamérica. Edición a cargo de Pablo Martín Aceña, Adolfo Meisel, Carlos Newland.Editada en la Fundación Empresa PúblicaLa industria textil moderna apareció en México tempranamente y creció
de forma continua a lo largo del siglo XIX. Sin embargo, esto no se tradujo
en un proceso de industrialización exitoso como resultado de altos costos
de transporte y fragilidad institucional: concepto que incluye la incertidumbre,
la debilidad y la fragmentación institucionales. La fragilidad institucional generó
una política arancelaría capturada que otorgaba bajos niveles de protección
efectiva a la industria, un mercado financiero atrasado que limitó los recursos
disponibles al crecimiento industrial, y un crecimiento en los costos de transporte
debido a las alcabalas. Los altos costos de transporte fragmentaron el
mercado nacional y como resultado generaron una industria geográficamente
dispersa.Modern texture manufacture appeared early in México and grew continuously
through the 19th century. Yet, it did not transíate into a successful
industrialization process as a result of naturally endowed high transportation
costs and institutional frailty: a concept that encompasses institutional uncertainty,
weakness and fragmentation. Institutional frailty generated a captured
tariff policy that gave low effective protection to the industry, a backward
financial market that limited resources available for industrial growth, and
increased transportation costs through inter-state tariff barriers. High transportation
costs fragmented the national market and as a result, the textile
industry grew geographically dispersed.Publicad
Nuclear Structure-Dependent Radiative Corrections to the Hydrogen Hyperfine Splitting
Radiative corrections to the Zemach contribution of the hydrogen hyperfine
splitting are calculated. Their contributions amount to ppm to the
HFS. The radiative recoil corrections are estimated to be ppm and
heavy particle vacuum polarization shifts the HFS by ppm. The status
of the nuclear-dependent contributions are considered. From the comparison of
theory and experiment the proton polarizability contribution of ppm is
found. The nuclear structure-dependent corrections to the difference
are also obtained.Comment: 19 pages, 3 tables, 2 Postscript figure
Large-scale manipulation of promoter DNA methylation reveals context-specific transcriptional responses and stability
BACKGROUND: Cytosine DNA methylation is widely described as a transcriptional repressive mark with the capacity to silence promoters. Epigenome engineering techniques enable direct testing of the effect of induced DNA methylation on endogenous promoters; however, the downstream effects have not yet been comprehensively assessed. RESULTS: Here, we simultaneously induce methylation at thousands of promoters in human cells using an engineered zinc finger-DNMT3A fusion protein, enabling us to test the effect of forced DNA methylation upon transcription, chromatin accessibility, histone modifications, and DNA methylation persistence after the removal of the fusion protein. We find that transcriptional responses to DNA methylation are highly context-specific, including lack of repression, as well as cases of increased gene expression, which appears to be driven by the eviction of methyl-sensitive transcriptional repressors. Furthermore, we find that some regulatory networks can override DNA methylation and that promoter methylation can cause alternative promoter usage. DNA methylation deposited at promoter and distal regulatory regions is rapidly erased after removal of the zinc finger-DNMT3A fusion protein, in a process combining passive and TET-mediated demethylation. Finally, we demonstrate that induced DNA methylation can exist simultaneously on promoter nucleosomes that possess the active histone modification H3K4me3, or DNA bound by the initiated form of RNA polymerase II. CONCLUSIONS: These findings have important implications for epigenome engineering and demonstrate that the response of promoters to DNA methylation is more complex than previously appreciated. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13059-022-02728-5
Nuclear Sizes and the Isotope Shift
Darwin-Foldy nuclear-size corrections in electronic atoms and nuclear radii
are discussed from the nuclear-physics perspective. Interpretation of precise
isotope-shift measurements is formalism dependent, and care must be exercised
in interpreting these results and those obtained from relativistic electron
scattering from nuclei. We strongly advocate that the entire nuclear-charge
operator be used in calculating nuclear-size corrections in atoms, rather than
relegating portions of it to the non-radiative recoil corrections. A
preliminary examination of the intrinsic deuteron radius obtained from
isotope-shift measurements suggests the presence of small meson-exchange
currents (exotic binding contributions of relativistic order) in the nuclear
charge operator, which contribute approximately 1/2%.Comment: 17 pages, latex, 1 figure -- Submitted to Phys. Rev. A -- epsfig.sty
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ConTra v2: a tool to identify transcription factor binding sites across species, update 2011
Transcription factors are important gene regulators with distinctive roles in development, cell signaling and cell cycling, and they have been associated with many diseases. The ConTra v2 web server allows easy visualization and exploration of predicted transcription factor binding sites in any genomic region surrounding coding or non-coding genes. In this new version, users can choose from nine reference organisms ranging from human to yeast. ConTra v2 can analyze promoter regions, 5′-UTRs, 3′-UTRs and introns or any other genomic region of interest. Hundreds of position weight matrices are available to choose from, but the user can also upload any other matrices for detecting specific binding sites. A typical analysis is run in four simple steps of choosing the gene, the transcript, the region of interest and then selecting one or more transcription factor binding sites. The ConTra v2 web server is freely available at http://bioit.dmbr.ugent.be/contrav2/index.php
Theory of Light Hydrogenlike Atoms
The present status and recent developments in the theory of light hydrogenic
atoms, electronic and muonic, are extensively reviewed. The discussion is based
on the quantum field theoretical approach to loosely bound composite systems.
The basics of the quantum field theoretical approach, which provide the
framework needed for a systematic derivation of all higher order corrections to
the energy levels, are briefly discussed. The main physical ideas behind the
derivation of all binding, recoil, radiative, radiative-recoil, and
nonelectromagnetic spin-dependent and spin-independent corrections to energy
levels of hydrogenic atoms are discussed and, wherever possible, the
fundamental elements of the derivations of these corrections are provided. The
emphasis is on new theoretical results which were not available in earlier
reviews. An up-to-date set of all theoretical contributions to the energy
levels is contained in the paper. The status of modern theory is tested by
comparing the theoretical results for the energy levels with the most precise
experimental results for the Lamb shifts and gross structure intervals in
hydrogen, deuterium, and helium ion , and with the experimental data on
the hyperfine splitting in muonium, hydrogen and deuterium.Comment: 230 pages, 106 figures, 24 tables. Discussion of muonic hydrogen is
added, list of references expanded, some minor corrections and amendment
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