5,392 research outputs found
A Comparison of the Effectiveness of Pitfall Traps and Winkler Litter Samples for Characterization of Terrestrial Ant (Formicidae) Communities in Temperate Savannas
Relatively few studies in temperate environments have compared pitfall traps and Winkler litter samples, two of the most commonly used ant (Formicidae) sampling protocols. Most of the comparative work has been performed in tropical and subtropical environments. Temperate studies have primarily taken place in forested environments. Our study focuses on the relative efficiency of these two methods in temperate oak savannas, the major ecotone connecting grasslands and deciduous forest in the Midwest. These environments are often maintained by fire and mechanical brush removal, which tends to decrease the amount of available leaf litter. We sampled 21 sites, varying in age since restoration from un-restored to 22 years of restoration activities in McHenry Co. Illinois. Each site was sampled with 30 pitfall traps and five Winkler litter samples. A total of 38 species in 17 genera in 5 subfamilies were captured and identified. Pitfall traps accounted for 37 of the species, while Winkler litter samples only captured 23 species, and only one species specific to that method. We conclude that in northern temperate savannas, pitfall traps were more effective and more efficient at characterizing the epigeic ant community than Winkler litter samples
Dynamic reservoir-condition microtomography of reactive transport in complex carbonates: effect of initial pore structure and initial brine pH
We study the impact of brine acidity and initial pore structure on the dynamics of fluid/solid reaction at high Péclet numbers and low Damköhler numbers. A laboratory μ-CT scanner was used to image the dissolution of Ketton, Estaillades, and Portland limestones in the presence of CO2-acidified brine at reservoir conditions (10 MPa and 50°C) at two injected acid strengths for a period of 4 hours. Each sample was scanned between 6 and 10 times at ∼4 μm resolution and multiple effluent samples were extracted. The images were used as inputs into flow simulations, and analysed for dynamic changes in porosity, permeability, and reaction rate. Additionally, the effluent samples were used to verify the image-measured porosity changes. We find that initial brine acidity and pore structure determine the type of dissolution. Dissolution is either uniform where the porosity increases evenly both spatially and temporally, or occurs as channelling where the porosity increase is concentrated in preferential flow paths. Ketton, which has a relatively homogeneous pore structure, dissolved uniformly at pH = 3.6 but showed more channelized flow at pH = 3.1. In Estaillades and Portland, increasingly complex carbonates, channelized flow was observed at both acidities with the channel forming faster at lower pH. It was found that the effluent pH, which is higher than that injected, is a reasonably good indicator of effective reaction rate during uniform dissolution, but a poor indicator during channelling. The overall effective reaction rate was up to 18 times lower than the batch reaction rate measured on a flat surface at the effluent pH, with the lowest reaction rates in the samples with the most channelized flow, confirming that transport limitations are the dominant mechanism in determining reaction dynamics at the fluid/solid boundary
Dynamic pore-scale reservoir-condition imaging of reaction in carbonates using synchrotron fast tomography
Synchrotron fast tomography was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 µm resolution over a period of 2 hours. Underground storage permanence is a major concern for carbon capture and storage. Pumping CO2 into carbonate reservoirs has the potential to dissolve geologic seals and allow CO2 to escape. However, the dissolution processes at reservoir conditions are poorly understood. Thus, time-resolved experiments are needed to observe and predict the nature and rate of dissolution at the pore scale. Synchrotron fast tomography is a method of taking high-resolution time-resolved images of complex pore structures much more quickly than traditional µ-CT . The Diamond Lightsource Pink Beam was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 µm resolution over a period of 2 hours. The images were segmented and the porosity and permeability were measured using image analysis and network extraction. Porosity increased uniformly along the length of the sample; however, the rate of increase of both porosity and permeability slowed at later times
The imaging of dynamic multiphase fluid flow using synchrotron-based x-ray microtomography at reservoir conditions
A pilot level decision analysis of thermionic reactor development strategy for nuclear electric propulsion
The development policy for thermionic reactors to provide electric propulsion and power for space exploration was analyzed to develop a logical procedure for selecting development alternatives that reflect the technical feasibility, JPL/NASA project objectives, and the economic environment of the project. The partial evolution of a decision model from the underlying philosophy of decision analysis to a deterministic pilot phase is presented, and the general manner in which this decision model can be employed to examine propulsion development alternatives is illustrated
A Comparison of the Effectiveness of Pitfall Traps and Winkler Litter Samples for Characterization of Terrestrial Ant (Formicidae) Communities in Temperate Savannas
Relatively few studies in temperate environments have compared pitfall traps and Winkler litter samples, two of the most commonly used ant (Formicidae) sampling protocols. Most of the comparative work has been performed in tropical and subtropical environments. Temperate studies have primarily taken place in forested environments. Our study focuses on the relative efficiency of these two methods in temperate oak savannas, the major ecotone connecting grasslands and deciduous forest in the Midwest. These environments are often maintained by fire and mechanical brush removal, which tends to decrease the amount of available leaf litter. We sampled 21 sites, varying in age since restoration from un-restored to 22 years of restoration activities in McHenry Co. Illinois. Each site was sampled with 30 pitfall traps and five Winkler litter samples. A total of 38 species in 17 genera in 5 subfamilies were captured and identified. Pitfall traps accounted for 37 of the species, while Winkler litter samples only captured 23 species, and only one species specific to that method. We conclude that in northern temperate savannas, pitfall traps were more effective and more efficient at characterizing the epigeic ant community than Winkler litter samples
Is the Birthing Unit Design Spatial Evaluation Tool valid for diverse groups?
© 2018 Australian College of Midwives Background: Awareness of the impact of the built environment on health care outcomes and experiences has led to efforts to redesign birthing environments. The Birth Unit Design Spatial Evaluation Tool was developed to inform such improvements, but it has only been validated with caseload midwives and women birthing in caseload models of care. Aim: To assess the content validity of the tool with four new participant groups: Birth unit midwives, Aboriginal or Torres Strait Islander women; women who had anticipated a vaginal birth after a caesarean; and women from refugee or culturally and linguistically diverse backgrounds. Methods: Participants completed a Likert-scale survey to rate the relevance of The Birth Unit Design Spatial Evaluation Tool's 69 items. Item-level content validity and Survey-level validity indices were calculated, with the achievement of validity set at >0.78 and >0.9 respectively. Results: Item-level content validity was achieved on 37 items for birth unit midwives (n = 10); 35 items for Aboriginal or Torres Strait Islander women (n = 6); 33 items for women who had anticipated a vaginal birth after a caesarean (n = 6); and 28 items for women from refugee or culturally and linguistically diverse backgrounds (n = 20). Survey-level content validity was not demonstrated in any group. Conclusion: Birth environment design remains significant to women and midwives, but the Birth Unit Design Spatial Evaluation Tool was not validated for these participant groups. Further research is needed, using innovative methodologies to address the subconscious level on which environment may influence experience and to disentangle the influence of confounding factors
Reservoir condition imaging of reactive transport in heterogeneous carbonates using fast synchrotron tomography - effect of initial pore structure and flow conditions
AbstractWe investigate the impact of initial pore structure and velocity field heterogeneity on the dynamics of fluid/solid reaction at high Péclet numbers (fast flow) and low Damköhler number (relatively slow reaction rates). The Diamond Lightsource Pink Beam was used to image dissolution of Estaillades and Portland limestones in the presence of CO2-saturated brine at reservoir conditions (10MPa and 50°C representing ~1km aquifer depth) at two flow rates for a period of 2h. Each sample was scanned between 51 and 94 times at 4.76-μm resolution and the dynamic changes in porosity, permeability, and reaction rate were examined using image analysis and flow modelling.We find that the porosity can either increase uniformly through time along the length of the samples, or may exhibit a spatially and temporally varying increase that is attributed to channel formation, a process that is distinct from wormholing, depending on initial pore structure and flow conditions. The dissolution regime was structure-dependent: Estaillades with a higher porosity showed more uniform dissolution, while the lower porosity Portland experienced channel formation. The effective reaction rates were up to two orders of magnitude lower than those measured on a flat substrate with no transport limitations, indicating that the transport of reactant and product is severely hampered away from fast flow channels
Mesenchymal adenomatous polyposis coli plays critical and diverse roles in regulating lung development.
BackgroundAdenomatous polyposis coli (Apc) is a tumor suppressor that inhibits Wnt/Ctnnb1. Mutations of Apc will not only lead to familial adenomatous polyposis with associated epithelial lesions, but will also cause aggressive fibromatosis in mesenchymal cells. However, the roles of Apc in regulating mesenchymal cell biology and organogenesis during development are unknown.ResultsWe have specifically deleted the Apc gene in lung mesenchymal cells during early lung development in mice. Loss of Apc function resulted in immediate mesenchymal cell hyperproliferation through abnormal activation of Wnt/Ctnnb1, followed by a subsequent inhibition of cell proliferation due to cell cycle arrest at G0/G1, which was caused by a mechanism independent of Wnt/Ctnnb1. Meanwhile, abrogation of Apc also disrupted lung mesenchymal cell differentiation, including decreased airway and vascular smooth muscle cells, the presence of Sox9-positive mesenchymal cells in the peripheral lung, and excessive versican production. Moreover, lung epithelial branching morphogenesis was drastically inhibited due to disrupted Bmp4-Fgf10 morphogen production and regulation in surrounding lung mesenchyme. Lastly, lung mesenchyme-specific Apc conditional knockout also resulted in altered lung vasculogenesis and disrupted pulmonary vascular continuity through a paracrine mechanism, leading to massive pulmonary hemorrhage and lethality at mid-gestation when the pulmonary circulation should have started.ConclusionsOur study suggests that Apc in lung mesenchyme plays central roles in coordinating the proper development of several quite different cellular compartments including lung epithelial branching and pulmonary vascular circulation during lung organogenesis
Die Operationalisierte Psychodynamische Diagnostik (OPD-2):Strukturniveau und psychiatrische Diagnose
Die Konzepte zur Persönlichkeitsstruktur von Kernberg und Rudolf sind die direkten Vorläufer der Strukturachse der Operationalisierten Psychodynamischen Diagnostik (OPD-2), welche hier zur Strukturmessung eingesetzt wird. Es wird ein Zusammenhang des Strukturniveaus mit psychiatrischen Diagnosen untersucht. Anhand von 125 Patienten wurden Gruppenvergleiche von Achse I- und Achse II-Störungen bezüglich der OPD-2-Strukturachse durchgeführt. Patienten mit Persönlichkeitsstörungen hatten ein hochsignifikant schlechteres Strukturniveau als Patienten mit Achse I-Störungen. Innerhalb der Cluster A, B und C gab es signifikante Unterschiede im Strukturniveau. Die Anzahl der Persönlichkeitsstörungen hatte dagegen keinen Effekt. Es zeigt sich ein deutlicher Zusammenhang zwischen dem Strukturniveau nach OPD-2 und verschiedenen psychiatrischen Diagnosen. Es gibt ansatzweise Bestätigungen für Kernbergs Klassifikation der Persönlichkeitsstörungen
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