Background:The Elegant Pitta(Pitta elegans)complex displays a remarkable diversity of morphological and bioacoustic traits across five taxa currently recognized as subspecies.They differ in plumage characteristics(suc...Background:The Elegant Pitta(Pitta elegans)complex displays a remarkable diversity of morphological and bioacoustic traits across five taxa currently recognized as subspecies.They differ in plumage characteristics(such as red versus black belly patches;supercilium color and extent;and white versus black throats),in lifestyle(resident versus migratory)and in vocalizations.We investigated the morphological,bioacoustic and ecological differences across all taxa after recent studies demostrated the importance of these traits in recognizing biological species limits across pittas.Methods:Morphometric analysis was carried out by measuring tarsus,wing,tail and bill lengths of 15 specimens at the Natural History Museum,UK,and plumages were inspected across 106 unique individuals from four different repositories.Bioacoustic analysis was based on 134 range-wide sound recordings.Two types of calls,territorial calls and alarm calls,were analyzed using different sets of parameters.Principal component analysis and the Isler Criterion were applied to the measurements.Playback trials were conducted to explore the levels of response of each taxon to the call types of the other taxa.Results:The territorial call of concinna exhibits a distinct two-element motif,while elegans,maria and virginalis utter a three-element motif in which the first two elements are given in quick succession.On the other hand,vigorsii,produces both two-element and three-element motifs with longer breaks in between elements.As further corroborated by the playback trials,the three taxa elegans,virginalis and maria form a tight vocal cluster,whereas each concinna and vigorsii are distinct.The alarm call turned out to be less diagnostic even though most taxa did roughly separate into different vocal clusters.Morphometric analysis failed to produce strong differences,but plumage distinctions among multiple taxa are pronounced.Conclusions:We suggest splitting the Elegant Pitta into three biological species based on bioacoustic and—less so—plumage evidence:(1)Temminck’s Elegant Pitta P.elegans(including subspecies elegans,virginalis and maria),(2)Wallace’s Elegant Pitta P.concinna(monotypic),and(3)Banda Elegant Pitta P.vigorsii(monotypic).展开更多
Introduction:Nitrogen enrichment of coastal salt marshes can induce feedbacks that alter ecosystem-level processes including primary production and carbon sequestration.Despite the rising interest in coastal blue carb...Introduction:Nitrogen enrichment of coastal salt marshes can induce feedbacks that alter ecosystem-level processes including primary production and carbon sequestration.Despite the rising interest in coastal blue carbon,the effects of chronic nutrient enrichment on blue carbon processes have rarely been measured in the context of experimental fertilization.Here,we examined the ecosystem-level effects of nitrate(NO3)enrichment on the green-house gas dynamics of a Spartina alterniflora-dominated salt marsh.We measured CO2 and CH4 fluxes using static chambers through two growing seasons in a salt marsh that was nitrogen-enriched for 13 years and compared fluxes to those from a reference marsh.Outcomes:We found that nitrogen enrichment increased gross primary productivity(GPP)by 7.7%and increased ecosystem respiration(Recd)by 20.8%.However,nitrogen enrichment had no discernible effect on net ecosystem exchange(NEE).Taken together,these results suggest that nitrogen-induced stimulation of Reco could transform this salt marsh from a carbon sink into a source of carbon to the atmos phere.Conclusion:Our results complement prior findings of nitrogen enrichment weakening soil structure and organic matter stability in tidal salt marshes,suggesting that increased nutrient inputs have the potential to alter the carbon storage function of these ecosystems through enhanced microbial respiration of previously sequestered carbon.展开更多
We obtain appropriate sharp bounds on Triebel-Lizorkin spaces for rough oscillatory inte- grals with polynomial phase. By using these bounds and using an extrapolation argument we obtain some new and previously known ...We obtain appropriate sharp bounds on Triebel-Lizorkin spaces for rough oscillatory inte- grals with polynomial phase. By using these bounds and using an extrapolation argument we obtain some new and previously known results for oscillatory integrals under very weak size conditions on the kernel functions.展开更多
We establish the L^p boundedness of Marcinkiewicz integral operators with kernels in theHardy space on a compact submanifold of finite type. Previously such boundedness properties were obtained when the submanifold is...We establish the L^p boundedness of Marcinkiewicz integral operators with kernels in theHardy space on a compact submanifold of finite type. Previously such boundedness properties were obtained when the submanifold is a sphere. Our result shows that what matters is not the symmetry, but a certain type of curvature property of the submanifold.展开更多
The optical absorption of semiconducting AgBr nanocubes is significantly increased by up to 5 times in the measured spectral range when they are bonded to the surface of dielectric SiO2 nanospheres through electrostat...The optical absorption of semiconducting AgBr nanocubes is significantly increased by up to 5 times in the measured spectral range when they are bonded to the surface of dielectric SiO2 nanospheres through electrostatic interaction. The absorption enhancement factor depends on the wavelength and the size of the SiO2 nanoparticles （NPs）. Finite-difference time-domain calculations provide the nearfield intensity mapping of a heterostructure that is composed of a AgBr nanocube in close contact with a SiO2 nanosphere. The electric-field distributions indicate the field enhancement near the SiO2/AgBr interface due to light scattering and absorption enhancement in the AgBr nanocube, implying that the enhanced scattering nearfield increases the absorption cross section of the AgBr nanocube. The absorption cross-section spectra calculated using Mie theory agree with the experimental observations. This discovery sheds light on the utilization of dielectric spherical particles to increase the absorption in semiconductor NPs, thus improving the light-harvesting efficiency for solar-energy conversion.展开更多
文摘Background:The Elegant Pitta(Pitta elegans)complex displays a remarkable diversity of morphological and bioacoustic traits across five taxa currently recognized as subspecies.They differ in plumage characteristics(such as red versus black belly patches;supercilium color and extent;and white versus black throats),in lifestyle(resident versus migratory)and in vocalizations.We investigated the morphological,bioacoustic and ecological differences across all taxa after recent studies demostrated the importance of these traits in recognizing biological species limits across pittas.Methods:Morphometric analysis was carried out by measuring tarsus,wing,tail and bill lengths of 15 specimens at the Natural History Museum,UK,and plumages were inspected across 106 unique individuals from four different repositories.Bioacoustic analysis was based on 134 range-wide sound recordings.Two types of calls,territorial calls and alarm calls,were analyzed using different sets of parameters.Principal component analysis and the Isler Criterion were applied to the measurements.Playback trials were conducted to explore the levels of response of each taxon to the call types of the other taxa.Results:The territorial call of concinna exhibits a distinct two-element motif,while elegans,maria and virginalis utter a three-element motif in which the first two elements are given in quick succession.On the other hand,vigorsii,produces both two-element and three-element motifs with longer breaks in between elements.As further corroborated by the playback trials,the three taxa elegans,virginalis and maria form a tight vocal cluster,whereas each concinna and vigorsii are distinct.The alarm call turned out to be less diagnostic even though most taxa did roughly separate into different vocal clusters.Morphometric analysis failed to produce strong differences,but plumage distinctions among multiple taxa are pronounced.Conclusions:We suggest splitting the Elegant Pitta into three biological species based on bioacoustic and—less so—plumage evidence:(1)Temminck’s Elegant Pitta P.elegans(including subspecies elegans,virginalis and maria),(2)Wallace’s Elegant Pitta P.concinna(monotypic),and(3)Banda Elegant Pitta P.vigorsii(monotypic).
基金Funding for this project was provided by the National Science Foundation[award DEB-1354124 to TJM,award DEB-1719621 to the TIDE Project,and awards DEB-1637630&DEB-1238212 to the PIE-LTER].The study was further supported by startup funds from Bryn Mawr College to TJM.
文摘Introduction:Nitrogen enrichment of coastal salt marshes can induce feedbacks that alter ecosystem-level processes including primary production and carbon sequestration.Despite the rising interest in coastal blue carbon,the effects of chronic nutrient enrichment on blue carbon processes have rarely been measured in the context of experimental fertilization.Here,we examined the ecosystem-level effects of nitrate(NO3)enrichment on the green-house gas dynamics of a Spartina alterniflora-dominated salt marsh.We measured CO2 and CH4 fluxes using static chambers through two growing seasons in a salt marsh that was nitrogen-enriched for 13 years and compared fluxes to those from a reference marsh.Outcomes:We found that nitrogen enrichment increased gross primary productivity(GPP)by 7.7%and increased ecosystem respiration(Recd)by 20.8%.However,nitrogen enrichment had no discernible effect on net ecosystem exchange(NEE).Taken together,these results suggest that nitrogen-induced stimulation of Reco could transform this salt marsh from a carbon sink into a source of carbon to the atmos phere.Conclusion:Our results complement prior findings of nitrogen enrichment weakening soil structure and organic matter stability in tidal salt marshes,suggesting that increased nutrient inputs have the potential to alter the carbon storage function of these ecosystems through enhanced microbial respiration of previously sequestered carbon.
文摘We obtain appropriate sharp bounds on Triebel-Lizorkin spaces for rough oscillatory inte- grals with polynomial phase. By using these bounds and using an extrapolation argument we obtain some new and previously known results for oscillatory integrals under very weak size conditions on the kernel functions.
文摘We establish the L^p boundedness of Marcinkiewicz integral operators with kernels in theHardy space on a compact submanifold of finite type. Previously such boundedness properties were obtained when the submanifold is a sphere. Our result shows that what matters is not the symmetry, but a certain type of curvature property of the submanifold.
文摘The optical absorption of semiconducting AgBr nanocubes is significantly increased by up to 5 times in the measured spectral range when they are bonded to the surface of dielectric SiO2 nanospheres through electrostatic interaction. The absorption enhancement factor depends on the wavelength and the size of the SiO2 nanoparticles （NPs）. Finite-difference time-domain calculations provide the nearfield intensity mapping of a heterostructure that is composed of a AgBr nanocube in close contact with a SiO2 nanosphere. The electric-field distributions indicate the field enhancement near the SiO2/AgBr interface due to light scattering and absorption enhancement in the AgBr nanocube, implying that the enhanced scattering nearfield increases the absorption cross section of the AgBr nanocube. The absorption cross-section spectra calculated using Mie theory agree with the experimental observations. This discovery sheds light on the utilization of dielectric spherical particles to increase the absorption in semiconductor NPs, thus improving the light-harvesting efficiency for solar-energy conversion.
