Mitral valve force balance: a quantitative assessment of annular and subvalvular forces

In vitro and in vivo models were proposed to evaluate the effects of ischemic mitral regurgitation and surgical repair on the function and mechanics of the heart’s mitral valve. In specific aim 1, a novel transducer was developed to measure the radially directed forces that may act on devices implanted to the mitral annulus. In an ovine model, radial forces were found to statistically increase with left ventricular pressure and were reduced in the setting of ischemic mitral regurgitation. In specific aim 2, the suture forces required to constrain true-sized and undersized annuloplasty rings to the mitral annulus of ovine animals was evaluated. Suture forces were observed to be larger on the anterior aspect of the rings and were elevated with annular undersizing. In specific aim 3, an in vitro simulator’s ability to mimic healthy and ischemic mitral regurgitation ovine mitral valve function was evaluated. After understanding the accuracy of the model, the in vitro ischemic mitral regurgitation model was used to evaluate the progressive effects of annuloplasty on strut and intermediary chordal tethering. The generated data and knowledge will contribute to the development of more durable devices and techniques to assess the significant clinical burden known as ischemic mitral regurgitation.Ph.D

A global method for calculating plant CSR ecological strategies applied across biomes world-wide

Competitor, stress‐tolerator, ruderal (CSR) theory is a prominent plant functional strategy scheme previously applied to local floras. Globally, the wide geographic and phylogenetic coverage of available values of leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA) (representing, respectively, interspecific variation in plant size and conservative vs. acquisitive resource economics) promises the general application of CSR strategies across biomes, including the tropical forests hosting a large proportion of Earth´s diversity.We used trait variation for 3068 tracheophytes (representing 198 families, six continents and 14 biomes) to create a globally calibrated CSR strategy calculator tool and investigate strategy?environment relationships across biomes world‐wide.Due to disparity in trait availability globally, co‐inertia analysis was used to check correspondence between a ?wide geographic coverage, few traits? data set and a ?restricted coverage, many traits? subset of 371 species for which 14 whole‐plant, flowering, seed and leaf traits (including leaf nitrogen content) were available. CSR strategy/environment relationships within biomes were investigated using fourth‐corner and RLQ analyses to determine strategy/climate specializations.Strong, significant concordance (RV = 0·597; P < 0·0001) was evident between the 14 trait multivariate space and when only LA, LDMC and SLA were used.Biomes such as tropical moist broadleaf forests exhibited strategy convergence (i.e. clustered around a CS/CSR median; C:S:R = 43:42:15%), with CS‐selection associated with warm, stable situations (lesser temperature seasonality), with greater annual precipitation and potential evapotranspiration. Other biomes were characterized by strategy divergence: for example, deserts varied between xeromorphic perennials such as Larrea divaricata, classified as S‐selected (C:S:R = 1:99:0%) and broadly R‐selected annual herbs (e.g. Claytonia perfoliata; R/CR‐selected; C:S:R = 21:0:79%). Strategy convergence was evident for several growth habits (e.g. trees) but not others (forbs).The CSR strategies of vascular plants can now be compared quantitatively within and between biomes at the global scale. Through known linkages between underlying leaf traits and growth rates, herbivory and decomposition rates, this method and the strategy?environment relationships it elucidates will help to predict which kinds of species may assemble in response to changes in biogeochemical cycles, climate and land use.Fil: Pierce, Simon. University Of Milan; ItaliaFil: Negreiros, Daniel. Universidade Federal de Minas Gerais; BrasilFil: Cerabolini, Bruno E. L.. Universidad de Insubria; ItaliaFil: Kattge, Jens. 1max Planck Institute For Biogeochemistr; AlemaniaFil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Grime, John Philip. University of Sheffield; Reino UnidoFil: Thompson, Ken. University of Sheffield; Reino UnidoFil: Hunt, Roderick. University of Exeter; Reino UnidoFil: Wilson, Peter J.. University of Sheffield; Reino UnidoFil: Buffa, Gabriella. University Ca’Foscari of Venice; ItaliaFil: Nyakunga, Oliver C.. University Ca’Foscari of Venice; ItaliaFil: Reich, Peter B.. University of Minnesota; Estados UnidosFil: Caccianiga, Marco. Università degli Studi di Milano; ItaliaFil: Mangili, Federico. Università degli Studi di Milano; ItaliaFil: Ceriani, Roberta M.. The Native Flora Centre; Italia. Università degli Studi di Milano; ItaliaFil: Luzzaro, Alessandra. Università degli Studi di Milano; ItaliaFil: Brusa, Guido. University of Insubria; ItaliaFil: Siefert, Andrew. University of California at Davis; Estados UnidosFil: Barbosa, Newton P. U.. Universidade Federal de Minas Gerais; BrasilFil: Chapin III, Francis Stuart. University Of Alaska; Estados UnidosFil: Cornwell, William K.. University of New South Wales; AustraliaFil: Fang, Jingyun. The Chinese Academy of Sciences; ChinaFil: Fernandes, Geraldo Wilson. Universidade Federal de Minas Gerais; BrasilFil: Garnier, Eric. Centre d’Écologie Fonctionnelle et Évolutive; FranciaFil: Le Stradic, Soizig. Université de Liège; BélgicaFil: Peñuelas, Josep. Global Ecology Unit; EspañaFil: Melo, Felipe P. L.. Universidade Federal de Pernambuco; BrasilFil: Slaviero, Antonio. University Ca’Foscari of Venice; ItaliaFil: Tabarelli, Marcelo. Universidade Federal de Pernambuco; BrasilFil: Tampucci, Duccio. Università degli Studi di Milano; Itali

Rooting depth and xylem vulnerability are independent woody plant traits jointly selected by aridity, seasonality, and water table depth

Evolutionary radiations of woody taxa within arid environments were made possible by multiple trait innovations including deep roots and embolism-resistant xylem, but little is known about how these traits have coevolved across the phylogeny of woody plants or how they jointly influence the distribution of species. We synthesized global trait and vegetation plot datasets to examine how rooting depth and xylem vulnerability across 188 woody plant species interact with aridity, precipitation seasonality, and water table depth to influence species occurrence probabilities across all biomes. Xylem resistance to embolism and rooting depth are independent woody plant traits that do not exhibit an interspecific trade-off. Resistant xylem and deep roots increase occurrence probabilities in arid, seasonal climates over deep water tables. Resistant xylem and shallow roots increase occurrence probabilities in arid, nonseasonal climates over deep water tables. Vulnerable xylem and deep roots increase occurrence probabilities in arid, nonseasonal climates over shallow water tables. Lastly, vulnerable xylem and shallow roots increase occurrence probabilities in humid climates. Each combination of trait values optimizes occurrence probabilities in unique environmental conditions. Responses of deeply rooted vegetation may be buffered if evaporative demand changes faster than water table depth under climate change

A global method for calculating plant CSR ecological strategies applied across biomes world-wide

Agraïments: The study has been supported by the TRY initiative on plant traits (www.try-db.org). The TRY initiative and database is hosted, developed and maintained by J. Kattge and G. Bönisch (Max-Planck-Institute for Biogeochemistry, Jena, Germany). TRY is/has been supported by DIVERSITAS, IGBP, the Global Land Project, the UK Natural Environment Research Council (NERC) through its program QUEST (Quantifying and Understanding the Earth System), the French Foundation for Biodiversity Research (FRB), and GIS "Climat, Environnement et Société" France. We thank Daniel Laughlin, Frédérique Louault, Belinda Medlyn, Julie Messier, Juli Pausas and Ian Wright for contributing data. The authors declare no conflict of interest.1. Competitor, stress-tolerator, ruderal (CSR) theory is a prominent plant functional strategy scheme previously applied to local floras. Globally, the wide geographic and phylogenetic coverage of available values of leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA) (representing, respectively, interspecific variation in plant size and conservative vs. acquisitive resource economics) promises the general application of CSR strategies across biomes, including the tropical forests hosting a large proportion of Earth's diversity. - 2. We used trait variation for 3068 tracheophytes (representing 198 families, six continents and 14 biomes) to create a globally calibrated CSR strategy calculator tool and investigate strategy-environment relationships across biomes world-wide. - 3. Due to disparity in trait availability globally, co-inertia analysis was used to check correspondence between a 'wide geographic coverage, few traits' data set and a 'restricted coverage, many traits' subset of 371 species for which 14 whole-plant, flowering, seed and leaf traits (including leaf nitrogen content) were available. CSR strategy/environment relationships within biomes were investigated using fourth-corner and RLQ analyses to determine strategy/climate specializations. - 4. Strong, significant concordance (RV = 0·597; P < 0·0001) was evident between the 14 trait multivariate space and when only LA, LDMC and SLA were used. - 5. Biomes such as tropical moist broadleaf forests exhibited strategy convergence (i.e. clustered around a CS/CSR median; C:S:R = 43:42:15%), with CS-selection associated with warm, stable situations (lesser temperature seasonality), with greater annual precipitation and potential evapotranspiration. Other biomes were characterized by strategy divergence: for example, deserts varied between xeromorphic perennials such as Larrea divaricata, classified as S-selected (C:S:R = 1:99:0%) and broadly R-selected annual herbs (e.g. Claytonia perfoliata; R/CR-selected; C:S:R = 21:0:79%). Strategy convergence was evident for several growth habits (e.g. trees) but not others (forbs). - 6. The CSR strategies of vascular plants can now be compared quantitatively within and between biomes at the global scale. Through known linkages between underlying leaf traits and growth rates, herbivory and decomposition rates, this method and the strategy-environment relationships it elucidates will help to predict which kinds of species may assemble in response to changes in biogeochemical cycles, climate and land use

A global method for calculating plant CSR ecological strategies applied across biomes world-wide

1. Competitor, stress-tolerator, ruderal (CSR) theory is a prominent plant functional strategy scheme previously applied to local floras. Globally, the wide geographic and phylogenetic coverage of available values of leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA) (representing, respectively, interspecific variation in plant size and conservative vs. acquisitive resource economics) promises the general application of CSR strategies across biomes, including the tropical forests hosting a large proportion of Earth's diversity. 2. We used trait variation for 3068 tracheophytes (representing 198 families, six continents and 14 biomes) to create a globally calibrated CSR strategy calculator tool and investigate strategy-environment relationships across biomes world-wide. 3. Due to disparity in trait availability globally, co-inertia analysis was used to check correspondence between a 'wide geographic coverage, few traits' data set and a 'restricted coverage, many traits' subset of 371 species for which 14 whole-plant, flowering, seed and leaf traits (including leaf nitrogen content) were available. CSR strategy/environment relationships within biomes were investigated using fourth-corner and RLQ analyses to determine strategy/climate specializations. 4. Strong, significant concordance (RV = 0.597; P < 0.0001) was evident between the 14 trait multivariate space and when only LA, LDMC and SLA were used. 5. Biomes such as tropical moist broadleaf forests exhibited strategy convergence (i.e. clustered around a CS/CSR median; C:S:R = 43: 42: 15%), with CS-selection associated with warm, stable situations (lesser temperature seasonality), with greater annual precipitation and potential evapotranspiration. Other biomes were characterized by strategy divergence: for example, deserts varied between xeromorphic perennials such as Larrea divaricata, classified as S-selected (C: S: R = 1:99:0%) and broadly R-selected annual herbs (e.g. Claytonia perfoliata; R/CR-selected; C:S:R = 21:0:79%). Strategy convergence was evident for several growth habits (e.g. trees) but not others (forbs). 6. The CSR strategies of vascular plants can now be compared quantitatively within and between biomes at the global scale. Through known linkages between underlying leaf traits and growth rates, herbivory and decomposition rates, this method and the strategy-environment relationships it elucidates will help to predict which kinds of species may assemble in response to changes in biogeochemical cycles, climate and land use

Plant functional trait change across a warming tundra biome

The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature–trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming