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521.
Emília P. Martins Terry J. Ord Sarah W. Davenport 《Behavioral ecology and sociobiology》2005,58(4):351-360
Complex displays composed of multiple, seemingly independent, units can result from sexual selection for increasingly variable, but redundant, displays and from potentially opposing selective pressures imposed by use of the display in multiple contexts. Our playback results support the latter, multireceiver hypothesis by confirming that two aspects of the sagebrush lizard headbob display (number of headbobs and use of display-specific body postures) are independently-meaningful components that are interpreted differently by different receivers. Male receivers use species-typical body postures to distinguish between aggressive and broadcast forms of the display, whereas female receivers are more attentive to the number of headbob motions, using these to distinguish male courtship from a challenge from a female competitor. Thus, display components are likely subject to different selective pressures and the display as a whole is evolving in response to a complex selective regime. Our example differs from other complex signals that have been considered in that both display elements involve dynamic motions (turned on and off by the display producer) as opposed to static signal elements (e.g., color, size). In addition, we found evidence that display structure is highly malleable, and that lizards both produce and respond to artificial displays that violate syntactic rules identified from field observations. Finally, our experiments demonstrate that a robotic lizard can be used effectively in playback studies of visual display behavior in lizards.Electronic Supplementary Material: S1. Movie clip of the robotic lizard producing a species-typical headbob display as in Fig. 1a. 相似文献
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Patrick Alexander Ray Mehmet Ümit Taner Katherine Elizabeth Schlef Sungwook Wi Hassaan Furqan Khan Sarah St George Freeman Casey Matthew Brown 《Journal of the American Water Resources Association》2019,55(4):920-937
There has recently been a return in climate change risk management practice to bottom‐up, robustness‐based planning paradigms introduced 40 years ago. The World Bank's decision tree framework (DTF) for “confronting climate uncertainty” is one incarnation of those paradigms. In order to better represent the state of the art in climate change risk assessment and evaluation techniques, this paper proposes: (1) an update to the DTF, replacing its “climate change stress test” with a multidimensional stress test; and (2) the addition of a Bayesian network framework that represents joint probabilistic behavior of uncertain parameters as sensitivity factors to aid in the weighting of scenarios of concern (the combination of conditions under which a water system fails to meet its performance targets). Using the updated DTF, water system planners and project managers would be better able to understand the relative magnitudes of the varied risks they face, and target investments in adaptation measures to best reduce their vulnerabilities to change. Next steps for the DTF include enhancements in: modeling of extreme event risks; coupling of human‐hydrologic systems; integration of surface water and groundwater systems; the generation of tradeoffs between economic, social, and ecological factors; incorporation of water quality considerations; and interactive data visualization. 相似文献
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Ashley A. Weaver Kristen M. Beavers R. Caresse Hightower Sarah K. Lynch Anna N. Miller Joel D. Stitzel 《Traffic injury prevention》2015,16(7):S153-S160
Objective: Low bone quality is a contributing factor to motor vehicle crash (MVC) injury. Quantification of occupant bone mineral density (BMD) is important from an injury causation standpoint. The first aim of this study was to validate a technique for measuring lumbar volumetric BMD (vBMD) from phantomless computed tomography (CT) scans. The second aim was to apply the validated phantomless technique to quantify lumbar vBMD in Crash Injury Research and Engineering Network (CIREN) occupants for correlation with age, fracture incidence, and osteopenia/osteoporosis diagnoses.Methods: Quantitative CT (qCT) and dual-energy X-ray absorptiometry (DXA) were collected prospectively for 50 subjects and used to validate a technique to measure vBMD from 281 phantomless CT scans of CIREN occupants. Hounsfield unit (HU) measurements were collected from the L1–L5 vertebrae, right psoas major muscle, and anterior subcutaneous fat for all subjects and from 3 phantom ports with known mg/cc calcium hydroxyapatite values for the validation group. qCT calibration was accomplished using regressions between the phantom HU and mg/cc values to convert L1–L5 HU values to mg/cc. A phantomless calibration technique was developed where the fat and muscle HU values were linearly regressed against fat (?69 mg/cc) and muscle (77 mg/cc) to establish a conversion for L1–L5 HU measurements to mg/cc. vBMD calculated from qCT versus the phantomless method was compared for the 50 subjects to assess agreement and a mg/cc osteopenia threshold was established using DXA T-scores. CIREN HU measurements were converted to mg/cc using the phantomless technique and the mg/cc osteopenia threshold was used to compare vBMD to age, fracture incidence, and osteopenia comorbidity classifications in CIREN.Results: Linear regression of lumbar vBMD derived from the qCT versus phantomless calibrations showed excellent agreement (R2 = 0.87, P <.0001). A 145 mg/cc threshold for osteopenia was established (sensitivity = 1, specificity = 0.57) and 44 CIREN occupants had vBMD below this threshold. Of these 44 occupants, 64% were not classified as osteopenic in CIREN, but vBMD suggested undiagnosed osteopenia. Age was negatively correlated with vBMD in both sexes (P <.0001) and CIREN occupants with less than 145 mg/cc vBMD sustained an average 1.7 additional rib/sternum fractures (P =.036).Conclusions: Because lumbar vBMD was estimated from phantomless CT scans with accuracy similar to qCT, the phantomless technique can be broadly applied to both prospectively and retrospectively assess patient bone quality for research and clinical studies related to MVCs, falls, and aging. 相似文献
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William?H.?ButlerEmail author Ashley?Monroe Sarah?McCaffrey 《Environmental management》2015,55(3):564-577
The Collaborative Forest Landscape Restoration Program (CFLRP), established in 2009, encourages collaborative landscape scale ecosystem restoration efforts on United States Forest Service (USFS) lands. Although the USFS employees have experience engaging in collaborative planning, CFLRP requires collaboration in implementation, a domain where little prior experience can be drawn on for guidance. The purpose of this research is to identify the ways in which CFLRP’s collaborative participants and agency personnel conceptualize how stakeholders can contribute to implementation on landscape scale restoration projects, and to build theory on dynamics of collaborative implementation in environmental management. This research uses a grounded theory methodology to explore collaborative implementation from the perspectives and experiences of participants in landscapes selected as part of the CFLRP in 2010. Interviewees characterized collaborative implementation as encompassing three different types of activities: prioritization, enhancing treatments, and multiparty monitoring. The paper describes examples of activities in each of these categories and then identifies ways in which collaborative implementation in the context of CFLRP (1) is both hindered and enabled by overlapping legal mandates about agency collaboration, (2) creates opportunities for expanded accountability through informal and relational means, and, (3) creates feedback loops at multiple temporal and spatial scales through which monitoring information, prioritization, and implementation actions shape restoration work both within and across projects throughout the landscape creating more robust opportunities for adaptive management. 相似文献
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CO2 is the main greenhouse gas which causes global climatic changes on larger scale. Many techniques have been utilised to capture CO2. Membrane gas separation is a fast growing CO2 capture technique, particularly gas separation by composite membranes. The separation of CO2 by a membrane is not just a process to physically sieve out of CO2 through the controlled membrane pore size. It mainly depends upon diffusion and solubility of gases, particularly for composite dense membranes. The blended components in composite membranes have a high capability to adsorb CO2. The adsorption kinetics of the gases may directly affect diffusion and solubility. In this study, we have investigated the adsorption behaviour of CO2 in pure and composite membranes to explore the complete understanding of diffusion and solubility of CO2 through membranes. Pure cellulose acetate (CA) and cellulose acetate-titania nanoparticle (CA-TiO2) composite membranes were fabricated and characterised using SEM and FTIR analysis. The results indicated that the blended CA-TiO2 membrane adsorbed more quantity of CO2 gas as compared to pure CA membrane. The high CO2 adsorption capacity may enhance the diffusion and solubility of CO2 in the CA-TiO2 composite membrane, which results in a better CO2 separation. The experimental data was modelled by Pseudo first-order, pseudo second order and intra particle diffusion models. According to correlation factor R2, the Pseudo second order model was fitted well with experimental data. The intra particle diffusion model revealed that adsorption in dense membranes was not solely consisting of intra particle diffusion. 相似文献
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The Influence of Two‐Stage Ditches with Constructed Floodplains on Water Column Nutrients and Sediments in Agricultural Streams 下载免费PDF全文
Robert T. Davis Jennifer L. Tank Ursula H. Mahl Sarah G. Winikoff Sarah S. Roley 《Journal of the American Water Resources Association》2015,51(4):941-955
The two‐stage ditch is a novel management practice originally implemented to increase bank stability through floodplain restoration in channelized agricultural streams. To determine the effects of two‐stage construction on sediment and nutrient loads, we monitored turbidity, and also measured total suspended solids (TSS), dissolved inorganic nitrogen (N) species, and phosphorus (P) after two‐stage ditch construction in reference and manipulated reaches of four streams. Turbidity decreased during floodplain inundation at all sites, but TSS and P, soluble reactive phosphorus (SRP) and total phosphorus (TP) decreased only in the two‐stage ditches with longer duration of inundation. Both TSS and TP were positively correlated within individual streams, but neither were correlated with turbidity. Phosphorus was elevated in the stream to which manure was applied adjacent to the two‐stage reach, but not the reference reach, suggesting that landscape nutrient management plans could restrict nutrient transport to the stream, ultimately determining the efficacy of instream management practices. In addition, ammonium and nitrate decreased in two‐stage reaches with lower initial N concentrations. Overall, results suggest that turbidity, TSS, and TP were reduced during floodplain inundation, but the two‐stage alone may not be effective for managing high inorganic N loads. 相似文献