Individual Beds Research Articles

Stratigraphy and depositional architecture of lobe complexes across a range of confinements: Examples from the Late Paleozoic Paganzo Basin, Argentina

Abstract The well-exposed, Late Paleozoic glacially-influenced Paganzo Basin offers a unique opportunity to compare and contrast the stratigraphy and depositional architecture of turbidite sheet/lobe complexes with distinct degrees of basin-scale confinements. These include sandstones deposited in narrow paleofjord (Quebrada Las Lajas), moderately narrow paleovalley (Quebrada Grande) and broad depression (Cerro Bola) that are part of the same synchronous transgressive-regressive succession recorded in the basin. This work emphasizes the importance of scales of observation and the importance in make the distinction between the degree of confinement experienced by individual flows and the degree to which the system as a whole is limited by the basin size and geometry. In Quebrada Las Lajas, sheet-like sandstones form lobe complexes largely reflecting the basin physiography. The succession was subdivided into two turbidite stages (Ts1 and 2), separated by a finer-grained interval (F1) that together represents lobe complexes and interlobe systems. Individual sandstone beds are laterally and longitudinally continuous and onlap the paleofjord walls, suggesting vertically-stacked beds. In Quebrada Grande paleovalley, the succession was subdivided into three stages (Ts1 to Ts3), representing lobe complexes, also separated by finer-grained packages (F1 and 2) ascribed to interlobe phases. Individual sandstone beds are truncated, thinning and pinching out, making them hard to correlate between logged sections. This depositional pattern may suggest that lateral stacking dominates during the construction of lobe complexes. At Cerro Bola, the succession was subdivided into five stratigraphic units (Ts1 to Ts5). These units also onlap the basin margin. Individual sandstone beds of Ts1 and Ts2 are similar to those recorded in Quebrada Grande area, also suggesting compensational stacking dominated systems. However, individual sandstone beds within Ts4 are thicker relative to the other units and more continuous longitudinally, reaching the basin margin thus pointing to larger volume flows ascribed to a vertically-stacked pattern. On the other hand, Ts3 and Ts5 correspond to the thinner sandstone beds in the succession and, as these intervals are as thick as the others, they may be attributed to lobe off-axis to fringe settings. In all three areas, the lobe complex geometry is determined by the basin-scale confinement and, at this scale, all of them are represented by more or less tabular, large sandstone bodies showing more similarities than differences. Each of these three successions record an upward increase in the sand-to-mud ratio, which may denote flow ponding or progradation of up-dip deltas that fed these systems.

Consumer evaluation of intra-sustainable trade-offs in pig production – A mixed-method approach to analyze different consumer segments

ABSTRACT In the ongoing public debate about livestock production systems and especially for pig production, natural living conditions, including sufficient space for each individual animal, outdoor access and litter bedding are the most discussed public issues. In contrast, many consumers are very price sensitive and additionally demand products to have high food safety and high quality. Thus, trade-offs arise for farmers, policymakers and all actors in the supply chain. Up to now, it is widely unknown how people react and deal with intra-sustainable trade-offs in conventional pig farming systems. Typical trade-offs occur, for example, when using farrowing crates for sows, or outdoor access for slaughter pigs. Against a background of little knowledge, a mixed-method approach was used. First, ten qualitative in-depth interviews with German citizens were conducted. There followed an online survey with 1,298 German citizens. Realistic pictures and texts (formulated in cooperation with farmer associations and association for the protection of farm animals) were used to provide the participants with information about trade-offs (farrowing crate and outdoor access). Participants were confronted with trade-offs regarding farrowing crate and outdoor access and were asked to evaluate the systems. Using a cluster analysis, four clusters (“Unsure,” “Vague decision makers”, “Animal welfare supporters,” and “Animal and environmental protectionists”) were identified to characterize consumers´ evaluation of the trade-offs. The findings of this exploratory multi-method approach show that the given information about the farrowing crate did not lead to more acceptance. Furthermore, the presented negative aspects about outdoor access did not change its positive image. This could be useful for policymakers and all actors in the pig supply chain.

A new age model for the Ordovician (Sandbian) K-bentonites in Oslo, Norway

During the Late Ordovician, large explosive volcanic eruptions deposited worldwide K-bentonites, including the Millbrig and Deicke K-bentonites in North America and the Kinnekulle K-bentonite in Scandinavia. We have studied a classical locality in Oslo containing one of the most complete sections of K-bentonites in Europe.In a 53 m section of Sandbian age, we discovered 33 individual K-bentonite beds, the most notable beds being the Kinnekulle and the upper Grimstorp K-bentonite. Magnetic susceptibility (MS) measurements on two intervals show significant periodicity peaks interpreted as Milankovitch cycles and thus astronomically forced changes in sediment supply and composition. These cycles fit remarkably well with both the expected Milankovitch periodicities for the Ordovician as well as the radiometric ages presented in this study and may represent one of the most convincing demonstrations of Milankovitch cycles from the lower Paleozoic so far. Five of the K-bentonites have been dated by high-precision chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) U-Pb zircon geochronology, where the Kinnekulle K-bentonite gives an age of 454.06 ± 0.43 Ma. We have integrated the new data and calculated an age model showing the sedimentation rates through the section and thereby the ages of each of the 33 K-bentonites. Using the age model, we further present a new age for the Sandbian-Katian stage boundary. The section in Oslo provides the highest resolution window into the Upper Ordovician K-bentonite succession so far and helps shed more light on the chronology of one of the most intense volcanic periods of the Paleozoic and the relationship with the global carbon cycle changes that followed.

Investigation of seismic attributes, depositional environments, and hydrocarbon sweet-spot distribution in the Serbin field, Taylor Formation, Southeast Texas

We have conducted seismic-attribute analysis at the Serbin field — in an area straddling Lee, Fayette, and Bastrop Counties and covering approximately [Formula: see text] (approximately [Formula: see text]) — using new, reprocessed, 3D seismic data to provide additional understanding of depositional environments and better predict the distribution of hydrocarbon sweet spots. We converted the 3D seismic volume into a log-lithology volume and integrated core data to examine the distribution of lithology and interpret depositional environments. By conducting multiattribute analysis, we predicted resistivity (deep-induction log) volume and generated a resistivity map to identify hydrocarbon sweet spots. Our results show that reservoir sandstones in the Serbin field are storm-dominated, shelf-sand deposits. Although individual sandstone beds are lenticular and discontinuous, they collectively constitute a sheet-like geometry, trending northeast to southwest. On the basis of resistivity maps and rock property versus seismic-amplitude crossplots, we differentiated reservoirs in the lower Taylor Formation into two zones: (1) a northwest, high-resistivity, high-acoustic impedance zone and (2) a southeast, low-resistivity, low-acoustic impedance zone. The results also indicated that hydrocarbon sweet spots in the Serbin field are characterized by high resistivity and high impedance. Furthermore, the log-lithology method, although fast and effective, is limited because it cannot take into account sandstone zones having low acoustic impedance.

Quantifying the stratigraphic and spatial facies distribution in an ancient mixed-influence delta

Analysis of the sedimentology and stratigraphic architecture of tightly spaced three dimensional outcrops reveals that the Turonian (Upper Cretaceous) Wall Creek Member of the Frontier Formation in the western Powder River Basin, Wyoming, USA, is not composed of one continuous coarsening upward succession but of a complex stacked delta system containing three distinct sequences (S1-S3), each with a unique facies distribution and architectural heterogeneity. The basal sequence S1 consists of a fluvial dominated delta with two distinct lobes. These lobes are spatially constrained to the northeastern study area and show a rapid facies transition from trough crossbedded mouthbar deposits to lower delta front turbidites. Low angle clinoforms suggest a low accommodation setting with main sediment transport to the south. The middle S2 sequence is common throughout the study area and contains an abundance of storm-derived deposits, including hummocky cross stratification, suggesting the transition to a wave and storm-dominated delta setting. Sediment transport is largely to the south controlled by wind induced shear stresses. Lastly, heterolithic trough crossbedded sandstones with flaser bedding and abundant thin mudstones and rip-up clasts are characteristic for sequence S3. These deposits are interpreted as tidal bars in a tidal influenced delta. Quantitative evaluation of facies in the Wall Creek Member sequences shows that the dimensions and connectivity (baffle or barrier competence) of fine-grained thin beds varies systematically within the three delta types. The S1 fluvial delta is largely composed of laterally continuous delta front turbidites with continuous fine-grained thin beds (mean length 21.1 m or 69.2 ft, max length 83.9 m or 275.2 ft) separating individual sandstone beds. Conversely, abundant bioturbation and intense scouring by storms results in high amalgamation of sandy beds in sequence S2 and a limited length of fine-grained thin beds (mean 8.5 m or 27.9 ft) in the wave-dominated delta sequence. Tidally influenced deposits of sequence S3 are largely composed of heterolithic trough crossbedded sandstones and mudstones with low bioturbation, resulting in an intermediate fine-grained thin bed deposit (mean 12.1 m or 39.7 ft).

Hydrodynamic Study of an Ebullated-bed Reactor in the H-oil Process

The effectiveness and performance of industrial hydro-processing ebullated bed reactors (EBRs) are highly dependent on the bed hydrodynamics and operating conditions. Hydrodynamics of ebullated bed reactors was studied in a cold model experimental setup. The results of a dynamic similarity test showed that the experimental data could be applied in the study of a large scale unit (Refinery of Lukoil, Burgas, Bulgaria) within a reasonable accuracy. Air and magnesium sulfate 20 wt% (MgSO4 + H2O) solution and solid catalyst particles were used as the gas, liquid and solid phases, respectively. For the design of experiments in the lab-scale cold-flow column, factorial method was introduced to study the influence of operating variables on the individual holdups and bubble characteristics. Pressure gradient method was used to estimate the individual holdups and bed porosity along the column, while photographic method was utilized to obtain images of the moving gas bubble. The images were analyzed using Ai Adobe illustrator CC (64 Bit) software to determine the bubbles geometric characteristics. Large gas bubbles were broken to smaller ones due to the increased turbulent intensity and shear forces at higher liquid velocities, reducing mass transfer resistances. Empirical correlations were developed for prediction of phase holdups and bed porosity with high accuracy. The results showed that liquid internal reflux ratio, which characterized the ebullated bed reactors has a predominant effect on the individual holdups and bubble size. A good agreement was observed between the results and available data in the literature.

Topographic Controls On the Development of Contemporaneous but Contrasting Basin-Floor Depositional Architectures

Research Article| October 16, 2018 Topographic Controls On the Development of Contemporaneous but Contrasting Basin-Floor Depositional Architectures Daniel Bell; Daniel Bell 1SedRESQ, School of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PL, U.K. Search for other works by this author on: GSW Google Scholar Christopher J. Stevenson; Christopher J. Stevenson 2School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, U.K. Search for other works by this author on: GSW Google Scholar Ian A. Kane; Ian A. Kane 1SedRESQ, School of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PL, U.K. Search for other works by this author on: GSW Google Scholar David M. Hodgson; David M. Hodgson 3The Stratigraphy Group, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, U.K. Search for other works by this author on: GSW Google Scholar Miquel Poyatos-Moré Miquel Poyatos-Moré 4Department of Geosciences, University of Oslo, 0371 Oslo, Norway Search for other works by this author on: GSW Google Scholar Journal of Sedimentary Research (2018) 88 (10): 1166–1189. https://doi.org/10.2110/jsr.2018.58 Article history first online: 16 Oct 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation Daniel Bell, Christopher J. Stevenson, Ian A. Kane, David M. Hodgson, Miquel Poyatos-Moré; Topographic Controls On the Development of Contemporaneous but Contrasting Basin-Floor Depositional Architectures. Journal of Sedimentary Research 2018;; 88 (10): 1166–1189. doi: https://doi.org/10.2110/jsr.2018.58 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract Sediment-laden gravity-driven-flow deposits on the basin floor are typically considered to form either discrete lobes that stack compensationally, or packages of laterally extensive beds, commonly termed “sheets.” These end-member stacking patterns are documented in several basinfills. However, whether they can coexist in a single basin, or there are intermediate or transitional stacking patterns, is poorly understood. An analysis of depositional architecture and stacking patterns along a 70 km dip-oriented transect in the Upper Broto Turbidite System (Jaca Basin, south-central Pyrenees, Spain), which displays disparate stacking patterns in contemporaneous strata, is presented. Proximal and medial deposits are characterized by discrete packages of clean sandstones with sharp bed tops which exhibit predictable lateral and longitudinal facies changes, and are interpreted as lobes. Distal deposits comprise both relatively clean sandstones and hybrid beds that do not stack to form lobes. Instead, localized relatively thick hybrid beds are inferred to have inhibited the development of lobes. Hybrid beds developed under flows which were deflected and entrained carbonate mud substrate off a carbonate slope that bounded the basin to the south; evidence for this interpretation includes: 1) divergent paleoflow indicators and hummock-like features in individual beds; 2) a decrease in hybrid-bed thickness and abundance away from the lateral confining slope; 3) a carbonate-rich upper division, not seen in more proximal turbidites. The study demonstrates the co-occurrence of different styles of basin-floor stacking patterns in the same stratigraphic interval, and suggests that characterization of deep-water systems as either lobes or sheets is a false dichotomy. You do not currently have access to this article.

Synthesis of carbon nanotube on stainless steel microfibrous composite—Comparison of direct and indirect growth and its application in fixed bed m-cresol adsorption

Two types of novel carbon nanotube (CNT) integrated stainless steel microfibrous (SSMF) composites were prepared through a combined wet lay-up papermaking, sintering and thermal chemical vapor deposition (CVD) process. Preparation methods with (indirect growth) and without (direct growth) the pretreatment using Fe-Mo/Al2O3 catalysts were applied to grow CNTs on SSMF support (SSMF-CNT and SSMF-CCNT, respectively). The composites were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption–desorption, mercury porosimetry, X-ray photoelectron spectroscopy (XPS) and Raman spectra. Results show that CNTs are successfully synthesized onto the support by both methods. In SSMF-CNT, CNTs grow on the surface of stainless steel microfibers while in SSMF-CCNT, CNTs grow on the surface of microfibers as well as in the network structure. The textures of CNTs in two composites are also quite different. CNTs on SSMF-CNT show better degree of graphitization than CNTs on SSMF-CCNT. Finally, fixed bed adsorption experiments of m-cresol were carried out to compare the adsorption efficiency of fixed bed filled with individual CNT particles and structured fixed bed filled with both CNT particles and CNT-microfibrous composites. Results have shown that the structured fixed beds with CNT-microfibrous composite show a smaller m-cresol adsorption capacity but lower pressure drop and enhanced mass transfer efficiency compared with the individual CNT particle bed. Comparison between SSMF-CNT and SSMF-CCNT shows that SSMF-CNT shows a higher mass transfer efficiency and utilization efficiency than SSMF-CCNT due to different growth forms and texture properties, indicating that direct method is more suitable for the preparation of CNT-microfibrous composites for pollutant removal in waste water.

Quantitative comparisons of depositional architectures of unconfined and confined turbidite sheet systems

Degree of confinement refers to the degree to which sediment gravity flows are influenced by the surrounding basin relief and interact with the basin margins, and is a key controlling factor in determining the depositional architectures of turbidite sheet systems. Two well exposed late Palaeozoic sandy turbidite sheet systems in the Paganzo Basin at Cerro Bola, north-west Argentina, termed Stages II and IV (unconfined and highly confined respectively), provide three-dimensional constraints on facies associations, stacking patterns, depositional geometries and evolution of these turbidite sheet systems. Cluster analysis has been applied to define facies associations in these two systems at an appropriate hierarchical level depending on the overall nature of the system. The overlap index (OI), OI = A0/A1, where A0 is the overlap area and A1 is the area of underlying depositional element, is adopted to quantitatively characterise the stacking patterns. The two turbidite sheet systems show contrasts in that: (1) Stage II is built up by four hierarchical elements, each stacked in a shingled or compensational way with the majority of overlap index values of 0.7 and 0.8, to form higher hierarchical elements, whereas in Stage IV, individual beds stack vertically with OI = 1, together forming the stage and (2) Four facies associations have been identified in Stage II by cluster analysis and they occur in a spatial sequence from axis to fringe; one facies association has been identified in Stage IV and it shows little variation spatially across the basin. In unconfined systems, depositional elements are self-organized, and autocyclic controls are dominant, whereas in highly confined systems, confinement has suppressed the autocyclic signal and systems are allocyclically controlled.

Within-weed bed architectural adaptation of branching pattern in Myriophyllum spicatum L.

Regarding architectural adaptations in aquatic plants caused by the velocity of water flow only scarce, older information is available. When studying different Myriophyllum spicatum L. specimen architecture in the same water body differences in individual main axes and branching pattern were detected at the upstream and at the downstream end of individual plant beds. Samples from the two locations showed significant differences in architectural composition. At the downstream parts of the water body individual plants were longer and the number of branches was higher, which is contributed to flow velocity.

Orbitally Forced Hydrological Balance During the Messinian Salinity Crisis: Insights From Strontium Isotopes (87Sr/86Sr) in the Vena del Gesso Basin (Northern Apennines, Italy)

AbstractThe 87Sr/86Sr ratio is a proxy of the hydrologic structure of marginal basins characterized by the mixing between marine and continental waters. This reliable paleoceanographic and paleoclimatic tool is considered a key to the reconstruction of high‐amplitude hydrologic changes that governed the evolution of the Mediterranean region during the Messinian salinity crisis (MSC), when reduced connections with the global ocean resulted in the deposition of the most studied Earth's salt giant. Paleohydrological dynamics leading to the deposition of the Primary Lower Gypsum during the first stage of the MSC were revealed by the study of the 87Sr/86Sr composition of 114 samples from the Vena del Gesso basin (Northern Apennines, Italy). The analysis of seven high‐resolution 87Sr/86Sr profiles from individual gypsum beds suggests a climatic influence of precessional‐scale orbital parameters during evaporite deposition. The variations of Sr isotope ratios over time indicate that gypsum precipitation started from a seawater body dominated by continental contributions, followed by a relative increase of marine input. The overall results show a gradual upward detachment from the global ocean 87Sr/86Sr curve, with crucial steps corresponding to the most extreme eccentricity minima, suggesting an orbital influence on the hydrological balance of the basin. Given the sedimentological and geochemical analogies shared by the Mediterranean marginal basins that hosted the Primary Lower Gypsum deposition, the 87Sr/86Sr evolution of the Vena del Gesso basin may be considered as indicative of Mediterranean‐scale hydrologic dynamics, driven by gradual reduction of exchanges with the Atlantic and variable freshwater input.

The seaweed fly (Coelopidae) can facilitate environmental survival and transmission of E. coli O157 at sandy beaches

The sustainable management of recreational beaches is essential for minimising risk of human exposure to microbial pathogens whilst simultaneously maintaining valuable ecosystem services. Decaying seaweed on public beaches is gaining recognition as a substrate for microbial contamination, and is a potentially significant reservoir for human pathogens in close proximity to beach users. Closely associated with beds of decaying seaweed are dense populations of the seaweed fly (Coelopidae), which could influence the spatio-temporal fate of seaweed-associated human pathogens within beach environments. Replicated mesocosms containing seaweed inoculated with a bioluminescent strain of the zoonotic pathogen E. coli O157:H7, were used to determine the effects of two seaweed flies, Coelopa frigida and C. pilipes, on E. coli O157:H7 survival dynamics. Multiple generations of seaweed flies and their larvae significantly enhanced persistence of E. coli O157:H7 in simulated wrack habitats, demonstrating that both female and male C. frigida flies are capable of transferring E. coli O157:H7 between individual wrack beds and into the sand. Adult fly faeces can contain significant concentrations of E. coli O157:H7, which suggests they are capable of acting as biological vectors and bridge hosts between wrack habitats and other seaweed fly populations, and facilitate the persistence and dispersal of E. coli O157:H7 in sandy beach environments. This study provides the first evidence that seaweed fly populations inhabiting natural wrack beds contaminated with the human pathogen E. coli O157:H7 have the capacity to amplify the hazard source, and therefore potential transmission risk, to beach users exposed to seaweed and sand in the intertidal zone. The risk to public health from seaweed flies and decaying wrack beds is usually limited by human avoidance behaviour; however, seaweed fly migration and nuisance inland plagues in urban areas could increase human exposure routes beyond the beach environment.

Tabularity of individual turbidite beds controlled by flow efficiency and degree of confinement

AbstractSubmarine lobes have various geometries and stacking patterns, whose differences are likely to be the result of variations in flow efficiency and degree of confinement. This study examines four contrasting units with differing flow efficiency and confinement, to evaluate their effects on bed geometries and stacking patterns. Three of these units occur in the Late Palaeozoic Paganzo Basin, north‐west Argentina: the Las Lajas system is developed in a 0·8 km wide palaeofjord; the Cerro Bola system (of which two different units were studied) was deposited in a larger sub‐basin, at least 20 km wide. The Paine C system of the late Cretaceous Magallanes Basin in Chile is confined by an incision surface 3 km wide. Seventy‐eight individual beds in the four units have been chosen to calculate flow efficiency and degree of confinement. Individual flow efficiency has been estimated semi‐quantitatively using the outcrop cross‐sectional area of the bed (as a proxy for flow volume) and percentage of mud in the beds (as a relative estimate for that in the flows). The degree of confinement experienced by the flows was assessed semi‐quantitatively by dividing the flow efficiency by the maximum preserved basin dimension. It is found that: (i) degree of confinement (efficiency divided by maximum preserved basin dimension) influences individual bed geometry, highly confined flows having a higher tabularity (smaller thinning rate); (ii) in highly confined settings, individual beds stack vertically, whereas in unconfined systems, they stack compensationally; (iii) highly confined or high efficiency flows have higher tabularity (smaller thinning rate), which implies that truly sheet‐like systems are only developed in highly confined and high efficiency systems. The generic model of architecture of submarine lobes and turbidite sheet systems, as a function of flow efficiency and degree of confinement, could be applied widely to sheet‐like systems both at outcrop and in the subsurface.

Architecture and morphodynamics of subcritical sediment waves in an ancient channel–lobe transition zone

AbstractIn modern systems, submarine channel–lobe transition zones show a well‐documented assemblage of depositional and erosional bedforms. In contrast, the stratigraphic record of channel–lobe transition zones is poorly constrained, because preservation potential is low and criteria have not been established to identify depositional bedforms in these settings. Several locations from an exhumed fine‐grained base of slope system (Unit B, Laingsburg depocentre, Karoo Basin, South Africa) show exceptional preservation of sandstone beds with distinctive morphologies and internal facies distributions. The regional stratigraphic context, lack of a basal confining surface, wave‐like morphology in dip section, size and facies characteristics support an interpretation of subcritical sediment waves within a channel–lobe transition zone setting. Some sediment waves show steep (10 to 25°) unevenly spaced (10 to 100 m) internal truncation surfaces that are dominantly upstream‐facing, which suggests significant spatio‐temporal fluctuations in flow character. Their architecture indicates that individual sediment wave beds accrete upstream, in which each swell initiates individually. Lateral switching of the flow core is invoked to explain the sporadic upstream‐facing truncation surfaces, and complex facies distributions vertically within each sediment wave. Variations in bedform character are related to the axial to marginal positions within a channel–lobe transition zone. The depositional processes documented do not correspond with known bedform development under supercritical conditions. The proposed process model departs from established mechanisms of sediment wave formation by emphasising the evidence for subcritical rather than supercritical conditions, and highlights the significance of lateral and temporal variability in flow dynamics and resulting depositional architecture.

Associations between ideational variables and bed net use in Madagascar, Mali, and Nigeria

BackgroundThe use of insecticide-treated bed nets (ITNs) is crucial to the prevention, control, and elimination of malaria. Using household surveys conducted in 2014–2015 by the Health Communication Capacity Collaborative project in Madagascar, Mali, and Nigeria, we compared a model of psychosocial influence, called Ideation, to examine how malaria-related variables influence individual and household bed net use in each of these countries. Evaluations of non-malaria programs have confirmed the value of the ideational approach, but it is infrequently used to guide malaria interventions. The study objective was to examine how well this model could identify potentially effective malaria prevention approaches in different contexts.MethodsSampling and survey designs were similar across countries. A multi-stage random sampling process selected female caregivers with at least one child under 5 years of age for interviews. Additional data were collected from household heads about bed net use and other characteristics of household members. The caregiver survey measured psychosocial variables that were subjected to bivariate and multivariate analysis to identify significant ideational variables related to bed net use.ResultsIn all three countries, children and adolescents over five were less likely to sleep under a net compared to children under five (OR = 0.441 in Madagascar, 0.332 in Mali, 0.502 in Nigeria). Adults were less likely to sleep under a net compared to children under five in Mali (OR = 0.374) and Nigeria (OR = 0.448), but not Madagascar. In all countries, the odds of bed net use were lower in larger compared to smaller households (OR = 0.452 in Madagascar and OR = 0.529 in Nigeria for households with 5 or 6 members compared to those with less than 5; and OR = 0.831 in Mali for larger compared to smaller households). Of 14 common ideational variables examined in this study, six were significant predictors in Madagascar (all positive), three in Mali (all positive), and two in Nigeria (both negative).ConclusionThis research suggests that the systematic use of this model to identify relevant ideational variables in a particular setting can guide the development of communication strategies and messaging, thereby improving the effectiveness of malaria prevention and control.

Effect of individual and community-level bed net usage on malaria prevalence among under-fives in the Democratic Republic of Congo

BackgroundUnderstanding the contribution of community-level long-lasting, insecticidal net (LLIN) coverage to malaria control is critical to planning and assessing intervention campaigns. The Democratic Republic of Congo (DRC), which has one of the highest burdens of malaria cases and deaths and has dramatically scaled up LLIN ownership in recent years thus it is an ideal setting to evaluate the effect of individual versus community-level use to prevent malaria among children under the age of 5.ResultsData were derived from the 2013–2014 DRC Demographic and Health Survey. Community-level LLIN usage was significantly associated with protection against malaria, even when individual-level LLIN usage was included in the model. In stratified analysis, higher levels of community LLIN coverage enhanced the protective effect of individual LLIN usage, resulting in lower malaria prevalence among individuals who used a LLIN. A sub-analysis of individual LLIN usage by insecticide type revealed deltamethrin-treated nets were more protective than permethrin-treated nets, suggesting that mosquitoes in the DRC are more susceptible to deltamethrin.ConclusionsThis study examines the effects of individual and community-level LLIN usage in young children in an area of high ITN usage. Individual and community LLIN usage were significantly associated with protection against malaria in children under 5 in the DRC. Importantly, the protective effect of individual LLIN usage against malaria is enhanced when community LLIN coverage is higher, demonstrating the importance of increasing community-level LLIN usage. LLINs treated with deltamethrin were shown to be more protective against malaria than LLINs treated with permethrin. Demographic and Health Surveys are thus a novel and important means of surveillance for insecticide resistance.

Effect of individual and community-level bed net usage on malaria prevalence among under-fives in the Democratic Republic of Congo

Effect of individual and community-level bed net usage on malaria prevalence among under-fives in the Democratic Republic of Congo

Architecture and genesis of prograding deep boundstone margins and debris-dominated carbonate slopes: Examples from the Permian Capitan Formation, Southern Guadalupe Mountains, West Texas

Steep, debris-rich, progradational carbonate slope systems have been well-documented around the world in a variety of settings and time periods. While the association of such slopes with deep microbial boundstone upper slope factories, the planar nature of their clinoform profiles, and their toe-of-slope trajectory patterns have been discussed thoroughly, the internal architecture and genesis of clinothems and the mechanics behind progradation remain poorly understood. Capitan Formation (Seven Rivers and Yates Formation equivalent) exposures in the southern Guadalupe Mountains of west Texas allow for examination of steep, prograding Upper Permian (Guadalupian) carbonate slope strata that are coeval with deep, skeletal-microbial boundstone reefs positioned on the upper slope (100–200m water depth). Measured section data tied to interpreted photomosaics and hand samples were collected within a 7 square-kilometer study area in Pine Canyon and the Frijole wall to document the deposits and architecture of the Capitan slopes. A subset of a regional airborne Lidar dataset was utilized for mapping declivities and orientations of clinoform surfaces.The outcrops reveal that Capitan middle to lower foreslopes are dominated by lenticular breccia deposits originating from the brittle failure of upper slope boundstone factories, with lesser intercalations of platform-derived carbonate grain-dominated deposits and bypassed siliciclastics. The observed lenticular carbonate breccia deposits stack hierarchically and exhibit lateral and upslope offsetting (compensational and backfilling) architecture in response to the slope topography of previously deposited debris. Over time, this process constructed lower to middle slope conical sediment bodies that coalesced laterally to form strike-extensive, debris-dominated aprons. Once these debris aprons filled the slope profile up to the level of in situ microbial boundstone production, substrate became available for the upper slope reefs to prograde. The advance of the boundstones overtop their own debris completed the development of a shelf-to-basin debris-dominated clinothem, and the process repeated resulting in boundstone margin and foreslope progradation.These Capitan foreslope architectures indicate that sustained, small-scale gravitational failure of the upper slope boundstones was the dominant resedimentation process that contributed to slope development. Single collapse events that produced individual breccia beds occurred at a much greater frequency than relative sea level fluctuations recorded on the platform-top, and variability in breccia matrix sediment suggests that boundstones were shedding material downslope throughout all stages of the accommodation cycle. We propose that boundstone accretion, local instability and failure, and resulting slope breccia deposition were somewhat independent of allocyclic, high-frequency accommodation changes, and that an autogenic control associated with deep oligophotic microbial margins is dominant during the development and progradation of steep, debris-dominated slope systems.

Benthic controls of resuspension in UK shelf seas: Implications for resuspension frequency

In situ measurements and ship-based resuspension experiments using annular flumes are used to determine sediment stability and critical erosion thresholds for four sites with significantly different sediment characteristics, located in the Celtic Sea at water depths of 100 m. Seasonal and spatial variability of sediment characteristics and erodability is examined, and found to be the result of changes in percentage of organic carbon in the surface sediments (R2 = 0.82) and bulk density (R2 = 0.73) respectively when individual characteristic bed parameters are considered. Principal component analysis and linear regression analysis are used to determine a predictive model for erosion threshold in the Celtic Sea (R2 = 0.99), based on grain size, sorting, kurtosis, bulk density, porosity, percentage fines, organic carbon content and chlorophyll a concentration. Physical sediment characteristics were found to be more significant controls of bed stability than biological factors. Local hydrodynamic conditions are used to determine the likelihood and frequency of resuspension given these critical erosion thresholds. Resuspension is driven by tidal currents, and is common year-round, leading to a constant re-working of bed sediments in particular at the muddier sites. This is confirmed by in situ measurements of suspended sediment concentration.

Interaction of healthcare worker hands and portable medical equipment: a sequence analysis to show potential transmission opportunities

BackgroundWhile research has demonstrated the importance of a clean health care environment, there is a lack of research on the role portable medical equipment (PME) play in the transmission cycle of healthcare-acquired infections (HAIs). This study investigated the patterns and sequence of contact events among health care workers, patients, surfaces, and medical equipment in a hospital environment.MethodsResearch staff observed patient care events over six different 24 h periods on six different hospital units. Each encounter was recorded as a sequence of events and analyzed using sequence analysis and visually represented by network plots. In addition, a point prevalence microbial sample was taken from the computer on wheels (COW).ResultsThe most touched items during patient care was the individual patient (850), bedrail (375), bed-surface (302), and bed side Table (223). Three of the top ten most common subsequences included touching PME and the patient: computer on wheels ➔ patient (62 of 274 total sequences, 22.6%, contained this sequence), patient ➔ COW (20.4%), and patient ➔ IV pump (16.1%). The network plots revealed large interconnectedness among objects in the room, the patient, PME, and the healthcare worker.ConclusionsOur results demonstrated that PME such as COW and IV pump were two of the most highly-touched items during patient care. Even with proper hand sanitization and personal protective equipment, this sequence analysis reveals the potential for contamination from the patient and environment, to a vector such as portable medical equipment, and ultimately to another patient in the hospital.