1,088 research outputs found

    Assessing Landscape Constraints on Species Abundance: Does the Neighborhood Limit Species Response to Local Habitat Conservation Programs?

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    Landscapes in agricultural systems continue to undergo significant change, and the loss of biodiversity is an ever-increasing threat. Although habitat restoration is beneficial, management actions do not always result in the desired outcome. Managers must understand why management actions fail; yet, past studies have focused on assessing habitat attributes at a single spatial scale, and often fail to consider the importance of ecological mechanisms that act across spatial scales. We located survey sites across southern Nebraska, USA and conducted point counts to estimate Ring-necked Pheasant abundance, an economically important species to the region, while simultaneously quantifying landscape effects using a geographic information system. To identify suitable areas for allocating limited management resources, we assessed land cover relationships to our counts using a Bayesian binomial-Poisson hierarchical model to construct predictive Species Distribution Models of relative abundance. Our results indicated that landscape scale land cover variables severely constrained or, alternatively, facilitated the positive effects of local land management for Ring-necked Pheasants

    Quantifying proliferative and surface marker heterogeneity in colony‐founding connective tissue progenitors and their progeny using time‐lapse microscopy

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    Connective tissue progenitors (CTPs) are defined as the heterogeneous population of tissue‐resident stem and progenitor cells that are capable of proliferating and differentiating into connective tissue phenotypes. The prevalence and variation in clonal progeny of CTPs can be characterized using a colony formation assay. However, colony assays do not directly assess the characteristics of the colony‐founding CTP. We performed large, field‐of‐view, time‐lapse microscopy to manually track colonies back to the founding cells. Image processing and analysis was used to characterize the colonies and their founding cells. We found that the traditional colony‐forming unit (CFU) assay underestimates the number of founding cells as colonies can be formed by more than one founding cell. After 6 days in culture, colonies do not completely express CD73, CD90, and CD105. Heterogeneity in colony cells was characterized by two cell populations, proliferative and spread cells. Regression modelling of duration of lag phase and doubling time by cell marker suggests the presence of CD90 and CD105 in CTP subpopulations with different proliferative capabilities. From mathematical modelling of clonal colonies, we quantitatively characterized proliferation, migration, and cell marker expression rates to identify desirable clones for selection. Direct assessment of colony formation parameters led to more accurate assessment of CFU heterogeneity. Furthermore, these parameters can be used to quantify the diversity and hierarchy of stem and progenitor cells from a cell source or tissue for tissue engineering applications

    Development and early experience from an intervention to facilitate teamwork between general practices and allied health providers: the Team-link study

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    Abstract. Background. This paper describes the development and implementation of an intervention to facilitate teamwork between general practice and outside allied and community health services and providers. Methods. A review of organizational theory and a qualitative study of 9 practices was used to design an intervention which was applied in four Divisions of General Practice and 26 urban practices. Clinical record review and qualitative interviews with participants were used to determine the key lessons from its implementation. Results. Facilitating teamwork across organizational boundaries was very challenging. The quality of the relationship between professionals was of key importance. This was enabled by joint education and direct communication between providers. Practice nurses were key links between general practices and allied and community health services. Conclusions. Current arrangements for Team Care planning provide increased opportunities for access to allied health. However the current paper based system is insufficient to build relationships or effectively share roles as part of a patient care team. Facilitation is feasible but constrained by barriers to communication and trust. 2010 Harris et al; licensee BioMed Central Ltd

    Endothelial Function Is Associated with White Matter Microstructure and Executive Function in Older Adults

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    Age-related declines in endothelial function can lead to cognitive decline. However, little is known about the relationships between endothelial function and specific neurocognitive functions. This study explored the relationship between measures of endothelial function (reactive hyperemia index; RHI), white matter (WM) health (fractional anisotropy, FA, and WM hyperintensity volume, WMH), and executive function (Trail Making Test (TMT); Trail B - Trail A). Participants were 36 older adults between the ages of 59 and 69 (mean age = 63.89 years, SD = 2.94). WMH volume showed no relationship with RHI or executive function. However, there was a positive relationship between RHI and FA in the genu and body of the corpus callosum. In addition, higher RHI and FA were each associated with better executive task performance. Tractography was used to localize the WM tracts associated with RHI to specific portions of cortex. Results indicated that the RHI-FA relationship observed in the corpus callosum primarily involved tracts interconnecting frontal regions, including the superior frontal gyrus (SFG) and frontopolar cortex, linked with executive function. These findings suggest that superior endothelial function may help to attenuate age-related declines in WM microstructure in portions of the corpus callosum that interconnect prefrontal brain regions involved in executive function

    Measurements of droplet size in shear-driven atomization using ultra-small angle x-ray scattering

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    [EN] Measurements of droplet size in optically-thick, non-evaporating, shear-driven sprays have been made using ultra-small angle x-ray scattering (USAXS). The sprays are produced by orifice-type nozzles coupled to diesel injectors, with measurements conducted from 1 - 24 mm from the orifice, spanning from the optically-dense near-nozzle region to more dilute regions where optical diagnostics are feasible. The influence of nozzle diameter, liquid injection pressure, and ambient density were examined. The USAXS measurements reveal few if any nanoscale droplets, in conflict with a popular computational model of diesel spray breakup. The average droplet diameter rapidly decreases with downstream distance from the nozzle until a plateau value is reached, after which only small changes are seen in droplet diameter. This plateau droplet size is consistent with the droplets being small enough to be stable with respect to further breakup. Liquid injection pressure and nozzle diameter have the biggest impact on droplet size, while ambient density has a smaller effect. (C) 2017 Published by Elsevier Ltd.X-ray spray research at Argonne is supported by the DOE Advanced Combustion Program. We acknowledge team leaders Gurpreet Singh and Leo Breton for their support. These experiments were performed at the 7-BM, 9-ID, and 15-ID beamlines of the Advanced Photon Source, Argonne National Laboratory. ChemMatCARS Sector 15 is principally supported by the Divisions of Chemistry (CHE) and Materials Research (DMR), National Science Foundation, under grant number NSF/CHE-1346572. Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-ACO2-06CH11357. R. Payri was funded by a Fulbright visiting scholar grant in collaboration with the Ministry of Education, Culture and Sports of Spain (reference PRX14/00331) while performing this work. J.P. Viera was funded by the Spanish MINECO grant EEBB-I-15-0976 under project TRA2012-36932.Kastengren, A.; Ilavsky, J.; Viera-Sotillo, JP.; Payri, R.; Duke, DJ.; Swantek, A.; Tilocco, FZ.... (2017). Measurements of droplet size in shear-driven atomization using ultra-small angle x-ray scattering. International Journal of Multiphase Flow. 92:131-139. https://doi.org/10.1016/j.ijmultiphaseflow.2017.03.005S1311399

    Computational and Experimental Investigation of Interfacial Area in Near-Field Diesel Spray Simulation

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    [EN] The dense spray region in the near-field of diesel fuel injection remains an enigma. This region is difficult to interrogate with light in the visible range and difficult to model due to the rapid interaction between liquid and gas. In particular, modeling strategies that rely on Lagrangian particle tracking of droplets have struggled in this area. To better represent the strong interaction between phases, Eulerian modeling has proven particularly useful. Models built on the concept of surface area density are advantageous where primary and secondary atomization have not yet produced droplets, but rather form more complicated liquid structures. Surface area density, a more general concept than Lagrangian droplets, naturally represents liquid structures, no matter how complex. These surface area density models, however, have not been directly experimentally validated in the past due to the inability of optical methods to elucidate such a quantity. Optical diagnostics traditionally measure near-spherical droplet size far downstream, where the spray is optically thin. Using ultra-small-angle x-ray scattering (USAXS) measurements to measure the surface area and x-ray radiography to measure the density, we have been able to test one of the more speculative parts of Eulerian spray modeling. The modeling and experimental results have been combined to provide insight into near-field spray dynamics.Authors acknowledge that part of this work was partially funded by the Spanish Ministry of Economy and Competitiveness in the frame of the COMEFF (TRA2014-59483-R) project.Pandal, A.; Pastor Enguídanos, JM.; Payri, R.; Kastengren, A.; Duke, DJ.; Matusik, KE.; Giraldo-Valderrama, JS.... (2017). Computational and Experimental Investigation of Interfacial Area in Near-Field Diesel Spray Simulation. SAE International Journal of Fuel and Lubricants. 10(2):1-9. doi:10.4271/2017-01-0859S1910

    Linking instantaneous rate of injection to X-ray needle lift measurements for a direct-acting piezoelectric injector

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    Internal combustion engines have been and still are key players in today's world. Ever increasing fuel consumption standards and the ongoing concerns about exhaust emissions have pushed the industry to research new concepts and develop new technologies that address these challenges. To this end, the diesel direct injection system has recently seen the introduction of direct-acting piezoelectric injectors, which provide engineers with direct control over the needle lift, and thus instantaneous rate of injection (ROI). Even though this type of injector has been studied previously, no direct link between the instantaneous needle lift and the resulting rate of injection has been quantified. This study presents an experimental analysis of the relationship between instantaneous partial needle lifts and the corresponding ROI. A prototype direct-acting injector was utilized to produce steady injections of different magnitude by partially lifting the needle. The ROI measurements were carried out at CMT-Motores Termicos utilizing a standard injection rate discharge curve indicator based on the Bosch method (anechoic tube). The needle lift measurements were performed at the Advanced Photon Source at Argonne National Laboratory. The analysis seeks both to contribute to the current understanding of the influence that partial needle lifts have over the instantaneous ROI and to provide experimental data with parametric variations useful for numerical model validations. Results show a strong relationship between the steady partial needle lift and the ROI. The effect is non-linear, and also strongly dependent on the injection pressure. The steady lift value at which the needle ceases to influence the ROI increases with the injection pressure. Finally, a transient analysis is presented, showing that the needle velocity may considerably affect the instantaneous ROI, because of the volume displaced inside the nozzle. Results presented in this study show that at constant injection pressure and energizing time, this injector has the potential to control many aspects of the ROI and thus, the heat release rate. Also, data presented are useful for numerical model validations, which would provide detailed insight into the physical processes that drive these observations, and potentially, to the effects of these features on combustion performance.The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (Argonne). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.Viera-Sotillo, JP.; Payri, R.; Swantek, AB.; Duke, DJ.; Sovis, N.; Kastengren, AL.; Powell, CF. (2016). Linking instantaneous rate of injection to X-ray needle lift measurements for a direct-acting piezoelectric injector. Energy Conversion and Management. 112:350-358. https://doi.org/10.1016/j.enconman.2016.01.038S35035811
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