Chemical Characterization and Source Apportionment of Household Fine Particulate Matter in Rural, Peri-urban, and Urban West Africa

Household air pollution in sub-Saharan Africa and other developing regions is an important cause of disease burden. Little is known about the chemical composition and sources of household air pollution in sub-Saharan Africa, and how they differ between rural and urban homes. We analyzed the chemical composition and sources of fine particles (PM2.5) in household cooking areas of multiple neighborhoods in Accra, Ghana, and in peri-urban (Banjul) and rural (Basse) areas in The Gambia. In Accra, biomass burning accounted for 39–62% of total PM2.5 mass in the cooking area in different neighborhoods; the absolute contributions were 10–45 μg/m3. Road dust and vehicle emissions comprised 12–33% of PM2.5 mass. Solid waste burning was also a significant contributor to household PM2.5 in a low-income neighborhood but not for those living in better-off areas. In Banjul and Basse, biomass burning was the single dominant source of cooking-area PM2.5, accounting for 74–87% of its total mass; the relative and absolute contributions of biomass smoke to PM2.5 mass were larger in households that used firewood than in those using charcoal, reaching as high as 463 μg/m3 in Basse homes that used firewood for cooking. Our findings demonstrate the need for policies that enhance access to cleaner fuels in both rural and urban areas, and for controlling traffic emissions in cities in sub-Saharan Africa

Deforming tachyon kinks and tachyon potentials

In this paper we investigate deformation of tachyon potentials and tachyon kink solutions. We consider the deformation of a DBI type action with gauge and tachyon fields living on D1-brane and D3-brane world-volume. We deform tachyon potentials to get other consistent tachyon potentials by using properly a deformation function depending on the gauge field components. Resolutions of singular tachyon kinks via deformation and applications of deformed tachyon potentials to scalar cosmology scenario are discussed.Comment: To appear in JHEP, 19 pages, 5 eps figures, minor changes and one reference adde

Sociobiological Control of Plasmid copy number

Background:
All known mechanisms and genes responsible for the regulation of plasmid replication lie with the plasmid rather than the chromosome. It is possible therefore that there can be copy-up mutants. Copy-up mutants will have within host selective advantage. This would eventually result into instability of bacteria-plasmid association. In spite of this possibility low copy number plasmids appear to exist stably in host populations. We examined this paradox using a computer simulation model.

Model:
Our multilevel selection model assumes a wild type with tightly regulated replication to ensure low copy number. A mutant with slightly relaxed replication regulation can act as a “cheater” or “selfish” plasmid and can enjoy a greater within-host-fitness. However the host of a cheater plasmid has to pay a greater cost. As a result, in host level competition, host cell with low copy number plasmid has a greater fitness. Furthermore, another mutant that has lost the genes required for conjugation was introduced in the model. The non-conjugal mutant was assumed to undergo conjugal transfer in the presence of another conjugal plasmid in the host cell.

Results:
The simulatons showed that if the cost of carrying a plasmid was low, the copy-up mutant could drive the wild type to extinction or very low frequencies. Consequently, another mutant with a higher copy number could invade the first invader. This process could result into an increasing copy number. However above a certain copy number within-host selection was overcompensated by host level selection leading to a rock-paper-scissor (RPS) like situation. The RPS situation allowed the coexistence of high and low copy number plasmids. The non-conjugal “hypercheaters” could further arrest the copy numbers to a substantially lower level.

Conclusions:
These sociobiological interactions might explain the stability of copy numbers better than molecular mechanisms of replication regulation alone

What traits are carried on mobile genetic elements, and why?

Although similar to any other organism, prokaryotes can transfer genes vertically from mother cell to daughter cell, they can also exchange certain genes horizontally. Genes can move within and between genomes at fast rates because of mobile genetic elements (MGEs). Although mobile elements are fundamentally self-interested entities, and thus replicate for their own gain, they frequently carry genes beneficial for their hosts and/or the neighbours of their hosts. Many genes that are carried by mobile elements code for traits that are expressed outside of the cell. Such traits are involved in bacterial sociality, such as the production of public goods, which benefit a cell's neighbours, or the production of bacteriocins, which harm a cell's neighbours. In this study we review the patterns that are emerging in the types of genes carried by mobile elements, and discuss the evolutionary and ecological conditions under which mobile elements evolve to carry their peculiar mix of parasitic, beneficial and cooperative genes

Lentiviral Hematopoietic Stem Cell Gene Therapy in Patients with Wiskott-Aldrich Syndrome.

iskott-Aldrich syndrome (WAS) is an inherited immunodeficiency caused by mutations in the gene encoding WASP, a protein regulating the cytoskeleton. Hematopoietic stem/progenitor cell (HSPC) transplants can be curative, but, when matched donors are unavailable, infusion of autologous HSPCs modified ex vivo by gene therapy is an alternative approach. We used a lentiviral vector encoding functional WASP to genetically correct HSPCs from three WAS patients and reinfused the cells after a reduced-intensity conditioning regimen. All three patients showed stable engraftment of WASP-expressing cells and improvements in platelet counts, immune functions, and clinical scores. Vector integration analyses revealed highly polyclonal and multilineage haematopoiesis resulting from the gene-corrected HSPCs. Lentiviral gene therapy did not induce selection of integrations near oncogenes, and no aberrant clonal expansion was observed after 20 to 32 months. Although extended clinical observation is required to establish long-term safety, lentiviral gene therapy represents a promising treatment for WAS

Satellite-to-satellite attitude control of a long-distance spacecraft formation for the Next Generation Gravity Mission

The paperpresentsthedesignandsomesimulatedresultsoftheattitudecontrolofasatelliteformation under studybytheEuropeanSpaceAgencyfortheNextGenerationGravityMission.Theformation consists oftwospacecraftswhich fly morethan200kmapartatanaltitudefromtheEarth'sgroundof between 300and400km.Theattitudecontrolmustkeeptheopticalaxesofthetwospacecraftaligned with amicroradianaccuracy(pointingcontrol).Thisismadepossiblebyspecific opticalsensors accompanyingtheinter-satellitelaserinterferometer,whichisthemainpayloadofthemission.These sensors alloweachspacecrafttoactuateautonomousalignmentafterasuitableacquisitionprocedure. Pointing controlisconstrainedbytheangulardrag-freecontrol,whichisimposedbymissionscience (Earth gravimetryatalowEarthorbit),andmustzerotheangularaccelerationvectorbelow0.01 μrad/s2 in thesciencefrequencyband.Thisismadepossiblebyultrafine accelerometersfromtheGOCE-class, whose measurementsmustbecoordinatedwithattitudesensorstoachievedrag-freeandpointing requirements.EmbeddedModelControlshowshowcoordinationcanbeimplementedaroundthe embedded modelsofthespacecraftattitudeandoftheformationframequaternion.Evidenceand discussion aboutsomecriticalrequirementsarealsoincludedtogetherwithextensivesimulatedresults of twodifferentformationtypes

Evaluación inicial de un método para adoptar eventos kaizen en el sector de la construcción

Currently, construction companies have shown a need to adopt process improvement systems in order to function competitively in the market. However, civil construction, compared to the manufacturing, still has deficiencies relating to the incorporation of new improvement systems. Thus, the use of Kaizen Events (KE) is one of the main mechanisms used to perfect processes during the production (execution) phase of a product, ensuring enhanced performance and added value to the client. The present research sought to evaluate a method for adopting KE in the construction sector. The data-gathering tools used were a questionnaire and a focus group where academics and/or experts who fit a specific profile participated. A methodological strategy for the development of the work was adopted under the approach of Design Science Research (DSR) and the theoretical referential was developed from a Systematic Literature Review (SLR). Improvements were made to the method to improve its applicability and functionality in real life scenarios using the results obtained. Accordingly, the results show horizons for future research on KE in civil construction.Actualmente, las empresas de construcción han demostrado la necesidad de adoptar sistemas de mejora de procesos para establecerse competitivamente en el mercado. Sin embargo, la construcción civil, en comparación con la manufactura, aún presenta deficiencias relacionadas con la adopción de nuevos sistemas de mejora continua. Es así que los Eventos Kaizen (EK) es uno de los principales mecanismos para perfeccionar los procesos durante la fase de producción (ejecución) de un producto, asegurando un mejor desempeño y agregando valor al cliente. La presente investigación tuvo como objetivo la evaluación de un método para adoptar EK en el sector de la construcción. La recolección de datos se realizó con un cuestionario (43 personas) y un grupo focal (6 personas) donde participaron académicos y/o expertos quienes cumplían un perfil determinado. Para el desarrollo del trabajo se adoptó una estrategia metodológica regida por la Investigación Basada en el Diseño (del inglés Design Science Research, DSR), y el referencial teórico fue desarrollado a partir de una Revisión Sistemática de Literatura (RSL). A través de los resultados obtenidos, se realizaron mejoras del método para lograr su aplicabilidad y funcionabilidad a un caso real. En consecuencia, los resultados muestran horizontes para futuras investigaciones sobre los EK en la construcción civi

Plasmids Increase the Competitive Ability of Plasmid-Bearing Cells Even When Transconjugants Are Poor Donors, as Shown by Computer Simulations

Bacterial cells often suffer a fitness cost after conjugative plasmids’ entry because these cells replicate slower than plasmid-free cells. Compensatory mutations may appear after tens of or a few hundred generations, reducing or eliminating this cost. A previous work based on a mathematical model and computer simulations has shown that plasmid-bearing cells already adapted to the plasmid may gain a fitness advantage when plasmids transfer into neighboring plasmid-free cells because these cells are still unadapted to the plasmid. These slow-growing transconjugants use fewer resources, which can benefit donor cells. However, opportunities for compensatory mutations in transconjugants increase if these cells become numerous (through replication or conjugation). Moreover, transconjugants also gain an advantage when transferring the plasmid, but the original donors may be too distant from conjugation events to gain an advantage. To understand which consequence prevails, we performed further computer simulations allowing versus banning transfer from transconjugants. The advantage to donors is higher if transconjugants do not transfer plasmids, mainly when donors are rare and when the plasmid transfer rate (from donors) is high. These results show that conjugative plasmids are efficient biological weapons even if the transconjugant cells are poor plasmid donors. After some time, conjugative plasmids gain other host-benefit genes, such as virulence and drug-resistance.info:eu-repo/semantics/publishedVersio