3,322 research outputs found

    The presumption of sociality: Social learning in diverse contexts in brown-headed cowbirds (Molothrus ater).

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    Data are presented on social and vocal learning in cowbirds (Molothrus ater) housed in large aviaries and given more degrees of freedom than in conventional experimental studies. The studies show that social and vocal outcomes are facultative responses to social contexts. Several findings are reviewed: First, cowbirds quickly self-organize into groups by age and sex; second, opportunities to interact across age and sex do exist and affect courtship competence; third, female cowbirds organize themselves differently in the presence and absence of male competition; and fourth, young, naive cowbirds show rapid and differential sensitivity to group dynamics. Taken as a whole, the data show that social Umwelten are dynamic, developmental ecologies. Solitude is a human presumption. Every quiet step is thunder to beetle life underfoot, a tug of impalpable thread on the web pulling the mate to mate and predator to prey, a beginning or an end. Every choice is a new beginning for the chosen.-Barbara Kingsolver, Prodigal Summer Terra firma provides humans with sure footing but sometimes narrow thinking about the sensory world of other inhabitants. The air-ground complex is one of myriad environments, many neithe

    Projected climate-induced faunal change in the western hemisphere

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    Climate change is predicted to be one of the greatest drivers of ecological change in the coming century. Increases in temperature over the last century have clearly been linked to shifts in species distributions. Given the magnitude of projected future climatic changes, we can expect even larger range shifts in the coming century. These changes will, in turn, alter ecological communities and the functioning of ecosystems. Despite the seriousness of predicted climate change, the uncertainty in climate-change projections makes it difficult for conservation managers and planners to proactively respond to climate stresses. To address one aspect of this uncertainty, we identified predictions of faunal change for which a high level of consensus was exhibited by different climate models. Specifically, we assessed the potential effects of 30 coupled atmosphere–ocean general circulation model (AOGCM) future-climate simulations on the geographic ranges of 2954 species of birds, mammals, and amphibians in the Western Hemisphere. Eighty percent of the climate projections based on a relatively low greenhouse-gas emissions scenario result in the local loss of at least 10% of the vertebrate fauna over much of North and South America. The largest changes in fauna are predicted for the tundra, Central America, and the Andes Mountains where, assuming no dispersal constraints, specific areas are likely to experience over 90% turnover, so that faunal distributions in the future will bear little resemblance to those of today

    Synthesis and Characterization of Two Novel Zinc(II) Complexes with Ciprofloxacin. Crystal Structure of [C17H19N3O3F]2 ⋅ [ZnCl4] ⋅ 2H2O

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    The complexation of ZnII ions with quinolone in aqueous solution depends mainly upon pH. To investigate the pH dependence of the complexation between ZnII and the quinolone derivative Ciprofloxacin (abbreviation cfH), UV-Vis spectroscopy was used. The crystal structure of the compound [C17H19N3O3F]2 ⋅ [ZnCl4] ⋅ 2H2O (compound I) was determined by X-ray diffraction, which showed the structure to be ionic, consisting of a tetrachlorozincate(II) dianion and two protonated, monocationic Ciprofloxacin molecules. Compound II ([Zn(cf)2] ⋅ 3H2O) was obtained as microcrystals from an aqueous solution of Ciprofloxacin hydrochloride and zine sulphate adjusted to pH = 8 by the addition of sodium hydroxide. Both complexes were characterized by elemental analysis, mass speetrometry, TG analysis and IR spectroscopy. From the analysis of these results we have proposed a probable mode of bonding for the complexation of ZnII to Ciprofloxacin in compound II

    Brain Specificity of Diffuse Optical Imaging: Improvements from Superficial Signal Regression and Tomography

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    Functional near infrared spectroscopy (fNIRS) is a portable monitor of cerebral hemodynamics with wide clinical potential. However, in fNIRS, the vascular signal from the brain is often obscured by vascular signals present in the scalp and skull. In this paper, we evaluate two methods for improving in vivo data from adult human subjects through the use of high-density diffuse optical tomography (DOT). First, we test whether we can extend superficial regression methods (which utilize the multiple source–detector pair separations) from sparse optode arrays to application with DOT imaging arrays. In order to accomplish this goal, we modify the method to remove physiological artifacts from deeper sampling channels using an average of shallow measurements. Second, DOT provides three-dimensional image reconstructions and should explicitly separate different tissue layers. We test whether DOT's depth-sectioning can completely remove superficial physiological artifacts. Herein, we assess improvements in signal quality and reproducibility due to these methods using a well-characterized visual paradigm and our high-density DOT system. Both approaches remove noise from the data, resulting in cleaner imaging and more consistent hemodynamic responses. Additionally, the two methods act synergistically, with greater improvements when the approaches are used together

    Yttrium-Catalyzed Amine–Silane Dehydrocoupling: Extended Reaction Scope with a Phosphorus-Based Ligand

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    The scope of the catalytic dehydrocoupling of primary and secondary amines with phenylsilanes has been investigated using [Y­{N­(SiMe<sub>3</sub>)<sub>2</sub>}<sub>3</sub>] and a four-coordinate analogue bearing a cyclometalated phosphonium methylide ligand. Inclusion of the phosphorus-based ligand on yttrium results in increased substrate scope in comparison to the tris­(amide) analogue. While reversible C–H bond activation of the cyclometalated ligand was observed in stoichiometric experiments, D-labeling experiments and DFT calculations suggest that reversible ligand activation is not involved in silazane formation under catalytic conditions. We suggest that the extended reaction scope with the four-coordinate yttrium phosphonium methylide complex relative to the three-coordinate yttrium (tris)­amide complex is a result of differences in the ease of amine inhibition of catalysis

    Comparison of geomechanical deformation induced by megatonne-scale CO2 storage at Sleipner, Weyburn, and In Salah

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    Geological storage of CO2 that has been captured at large, point source emitters represents a key potential method for reduction of anthropogenic greenhouse gas emissions. However, this technology will only be viable if it can be guaranteed that injected CO2 will remain trapped in the subsurface for thousands of years or more. A significant issue for storage security is the geomechanical response of the reservoir. Concerns have been raised that geomechanical deformation induced by CO2 injection will create or reactivate fracture networks in the sealing caprocks, providing a pathway for CO2 leakage. In this paper, we examine three large-scale sites where CO2 is injected at rates of ∼1 megatonne/y or more: Sleipner, Weyburn, and In Salah. We compare and contrast the observed geomechanical behavior of each site, with particular focus on the risks to storage security posed by geomechanical deformation. At Sleipner, the large, high-permeability storage aquifer has experienced little pore pressure increase over 15 y of injection, implying little possibility of geomechanical deformation. At Weyburn, 45 y of oil production has depleted pore pressures before increases associated with CO2 injection. The long history of the field has led to complicated, sometimes nonintuitive geomechanical deformation. At In Salah, injection into the water leg of a gas reservoir has increased pore pressures, leading to uplift and substantial microseismic activity. The differences in the geomechanical responses of these sites emphasize the need for systematic geomechanical appraisal before injection in any potential storage sit
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