The strong global dimension of piecewise hereditary algebras

Let T be a tilting object in a triangulated category equivalent to the bounded derived category of a hereditary abelian category with finite dimensional homomorphism spaces and split idempotents. This text investigates the strong global dimension, in the sense of Ringel, of the endomorphism algebra of T. This invariant is expressed using the infimum of the lengths of the sequences of tilting objects successively related by tilting mutations and where the last term is T and the endomorphism algebra of the first term is quasi-tilted. It is also expressed in terms of the hereditary abelian generating subcategories of the triangulated category.Comment: Final published version. After refereeing, historical considerations were added and the length of the article was reduced: Introduction and Section 1 were reformulated; Subsection 2.1 was moved to Section 1 (with an abridged proof); Subsection 3.2 was reformulated (with an abridged proof); The proof in A.5 was rewritten (now shorter); And minor rewording was processed throughout the articl

Sprouty2 mediated tuning of signalling is essential for somite myogenesis

Background: Negative regulators of signal transduction cascades play critical roles in controlling different aspects of normal embryonic development. Sprouty2 (Spry2) negatively regulates receptor tyrosine kinases (RTK) and FGF signalling and is important in differentiation, cell migration and proliferation. In vertebrate embryos, Spry2 is expressed in paraxial mesoderm and in forming somites. Expression is maintained in the myotome until late stages of somite differentiation. However, its role and mode of action during somite myogenesis is still unclear. Results: Here, we analysed chick Spry2 expression and showed that it overlaps with that of myogenic regulatory factors MyoD and Mgn. Targeted mis-expression of Spry2 led to inhibition of myogenesis, whilst its C-terminal domain led to an increased number of myogenic cells by stimulating cell proliferation. Conclusions: Spry2 is expressed in somite myotomes and its expression overlaps with myogenic regulatory factors. Overexpression and dominant-negative interference showed that Spry2 plays a crucial role in regulating chick myogenesis by fine tuning of FGF signaling through a negative feedback loop. We also propose that mir-23, mir-27 and mir-128 could be part of the negative feedback loop mechanism. Our analysis is the first to shed some light on in vivo Spry2 function during chick somite myogenesis

Integration of very high-resolution stereo satellite images and airborne or satellite Lidar for Eucalyptus canopy height estimation

Eucalyptus plantations cover extensive areas in tropical regions and require accurate growth monitoring for efficient management. Traditional in-situ measurements, while necessary, are labor-intensive and impractical for large-scale assessments. Very high-resolution satellite stereo imagery is playing an increasingly important role in the estimation of fine Digital Surface Models (DSMs) across landscapes. However, its ability to estimate canopy height models (CHMs) has not been widely investigated. This study investigates the integration of high-resolution satellite stereo imagery from the Pleiades sensor with airborne or satellite Lidar data to estimate canopy height over eucalyptus plantations. Two study sites were selected in Brazil, representing flat and semi-mountainous topographies, Mato Grosso do Sul (MS) and Sao Paulo (SP), respectively. Digital Surface Models generated from Pleiades images (DSMP) were combined with Digital Terrain Models extracted from airborne Lidar data (DTMALS) to create Canopy Height Models (CHMALS). The evaluation of the CHMALS was based on two in situ canopy height measurements (Hmax and Hmean). For the SP site, the CHMALSmax, which is the average height of top 10% pixel values within each plot, correlated well with in situ Hmean, which is the average height of 10 central trees (r = 0.98), showing a bias of 1.4 m, RMSE of 3.1 m, and rRMSE of 18.5%. At the MS site, CHMALSmax demonstrated a bias of 1.9 m, RMSE of 2.3 m, rRMSE of 17.3%, and r correlation of 0.92. Despite a tendency to underestimate heights below 20 m in young tree plantations with open canopy, the results indicate reliable canopy height estimation. The study also investigates the potential of Global Ecosystem Dynamics Investigation (GEDI) elevation data as an alternative to DTMALS in absence of airborne Lidar data. The resulting CHMGedi is promising but slightly less accurate than Lidar-based CHMs. The best GEDI-based CHM (CHMGedimax) showed a bias and rRMSE of 1.3 m and 20.5% for the SP site, and 2.2 m and 24.9% for the MS site. These findings highlight the potential for integrating Pleiades and Lidar data for efficient and accurate canopy height monitoring in eucalyptus plantations

Integrating MODIS-derived indices for eucalyptus stand volume estimation: an evaluation of MODIS gross primary productivity

Accurate estimates of stand volume dynamics in Eucalyptus plantations is critical for sustainable forest management and wood production. This study investigates the integration of MODIS-derived indices, such as gross primary productivity (GPP), net photosynthesis (PSN) and normalized difference vegetation index (NDVI), with traditional age-based methods to improve stand volume estimation in Eucalyptus plantations. MODIS GPP was first evaluated against flux tower measurements, showing moderate agreement and systematic biases, particularly during periods of highest and lowest productivity in the first years after planting, with an RMSE of 19.65 gC m-2 8day-1 and R2 of 0.38. Multiple linear regression (MLR) and two machine learning models, including random forest (RF) and stochastic gradient boosting (SGB), were used to estimate stand volume by incorporating cumulative MODIS indices (Cgpp, Cpsn and Cndvi) and stand age. The SGB model showed the best performance using the full dataset, including stands aged from 1.6 to 8.4 years, with an RMSE of 22.63 m3 ha-1, an rRMSE of 17.15% and an R2 of 0.90. We showed that including cumulative indices from the first two years of growth significantly improved the model’s ability to predict growth dynamics in middle-aged to mature stands. These results highlight the utility of MODIS productivity products for medium to large-scale plantation management, providing scalable and cost-effective monitoring of stand volume

Improved estimates of biomass expansion factors and root-to-shoot ratios: An approach for different forest types across a climatic gradient in Brazil

Advancements in the current state of the art of the key drivers of biomass expansion factor (BEF) and the root-to-shoot ratio (R) are crucial for producing accurate information on forest biomass and carbon stocks. Hence, we compiled a nationally representative dataset encompassing diverse tree growth stages and climatic gradients. In this study, we propose models to improve BEF and R estimates at the tree level for Eucalyptus and Pinus plantations in Brazil. In general, the BEF values were more representative (91.7%) in the database than the R values (8.3%) due to the high cost of collecting coarse roots. Regarding genera, Eucalyptus was more extensively sampled (89.9%) than Pinus (10.1%), reflecting the predominance of Eucalyptus as the most widely planted genus in Brazil. The average BEF and R values calculated in this study were 1.16 and 0.22, respectively, for Eucalyptus spp. and 1.22 and 0.31, respectively, for Pinus spp. In predicting the BEFs, the random effects in the linear mixed model that significantly captured the variations in Eucalyptus and Pinus spp. were temperature and age class, respectively. The fixed effects for Eucalyptus spp. included diameter, height, and age, while for Pinus spp., they were the Köppen climate classification, species, slenderness degree, and age. R estimates were mainly influenced by precipitation and age for both genera, with slenderness and diameter specifically affecting Eucalyptus spp., and height being a driving factor for Pinus spp. Our findings discourage the use of fixed or default values for BEF and R across locations with different climates and growing conditions to reduce uncertainties in carbon accounting and greenhouse gas inventories

Studying ecophysiological patterns to improve the management of high-productivity Eucalypt plantations: the EUCFLUX project

Global climatic changes may deeply affect the functioning of Eucalyptus plantations. It is therefore crucial to gain knowledge on the drivers of Eucalyptus productivity, carbon (C) allocation and resource-use efficiency in order to ensure a sustained productivity. These data are key to improve the productivity of Eucalyptus plantations and reduce their impacts on natural resources towards sustainable management. Building on the innovative results obtained in its first phase (2007-2017), the second phase of the EUCFLUX project, initiated in 2018, aims to enhance our knowledge on eucalypt plantations functioning at various spatiotemporal scales. The EUCFLUX study site is located on a commercial clonal plantation of ca 260 ha in Southern Brazil. The project will specifically 1) quantify the fluxes of energy, C and water along a complete rotation using the Eddy Covariance technique, girth inventories, litter and C content surveys and flux chambers; and assess the effects of forest plantations on soil water availability down to 10m and water table 2) use high-resolution dendrometers and anatomical analyses to study the determinism of growth 3) combine field data, high resolution remote sensing and modelling to upscale our knowledge of eucalypt functioning from site to regional scales and 4) compare the functional responses of more than 16 eucalypt genotypes (clonal and seed-origin) in a common-environment field trial, in order to evaluate the generality of the results obtained on the main clone, but also to evaluate how different are the functional responses of coppice and planted eucalypt trees

Studying ecophysiological patterns to improve the management of high-productivity Eucalypt plantations: the EUCFLUX project

Global climatic changes may deeply affect the functioning of Eucalyptus plantations, especially through the increase in frequency and duration of droughts and storms. However, the long-term responses of trees to the interactions of the different changing environmental factors remain largely unknown. It is therefore crucial to gain knowledge on the drivers of Eucalyptus productivity, carbon (C) allocation and resource-use efficiency in order to ensure a sustained productivity. These data are key to improve the productivity of Eucalyptus plantations and reduce their impacts on natural resources towards sustainable management. Building on the innovative results obtained in its first phase (2007-2017), the second phase of the EUCFLUX project, initiated in 2018, aims to enhance our knowledge on Eucalypt plantations functioning at various spatiotemporal scales. The EUCFLUX study site is located on a commercial clonal plantation of ca 260 ha in the state of Sao Paulo, Brazil. The project will specifically 1) quantify the fluxes of energy, C and water along a complete rotation (7 years) using the Eddy Covariance technique, girth inventories, litter and C content surveys and flux chambers; and assess the effects of forest plantations on soil water availability down to 10m and water table 2) use high-resolution dendrometers and anatomical analyses to study the determinism of growth and C allocation 3) combine field data, high resolution remote sensing and ecophysiological modelling to upscale our knowledge of Eucalypt functioning from site to regional scales and 4) compare the functional responses of more than 16 Eucalypt genotypes (clonal and seed-origin) in a common-environment field trial, in order to evaluate the generality of the results obtained on the main clone, but also to evaluate how different are the functional responses of coppice and planted Eucalypt trees. This poster will describe the EUCFLUX project and discuss how it can help designing new adaptive management guidelines