Unveiling African rainforest composition and vulnerability to global change.

Africa is forecasted to experience large and rapid climate change1 and population growth2 during the twenty-first century, which threatens the world's second largest rainforest. Protecting and sustainably managing these African forests requires an increased understanding of their compositional heterogeneity, the environmental drivers of forest composition and their vulnerability to ongoing changes. Here, using a very large dataset of 6 million trees in more than 180,000 field plots, we jointly model the distribution in abundance of the most dominant tree taxa in central Africa, and produce continuous maps of the floristic and functional composition of central African forests. Our results show that the uncertainty in taxon-specific distributions averages out at the community level, and reveal highly deterministic assemblages. We uncover contrasting floristic and functional compositions across climates, soil types and anthropogenic gradients, with functional convergence among types of forest that are floristically dissimilar. Combining these spatial predictions with scenarios of climatic and anthropogenic global change suggests a high vulnerability of the northern and southern forest margins, the Atlantic forests and most forests in the Democratic Republic of the Congo, where both climate and anthropogenic threats are expected to increase sharply by 2085. These results constitute key quantitative benchmarks for scientists and policymakers to shape transnational conservation and management strategies that aim to provide a sustainable future for central African forests.

Asynchronous carbon sink saturation in African and Amazonian tropical forests.

Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions1-3. Climate-driven vegetation models typically predict that this tropical forest 'carbon sink' will continue for decades4,5. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53-0.79), in contrast to the long-term decline in Amazonian forests6. Therefore the carbon sink responses of Earth's two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature7-9. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth's intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth's climate.

The puzzling ecology of African Marantaceae forests.

Marantaceae forests are tropical rainforests characterized by a continuous understory layer of perennial giant herbs and a near absence of tree regeneration. Although widespread in West-Central Africa, Marantaceae forests have rarely been considered in the international literature. Yet, they pose key challenges and opportunities for theoretical ecology that transcend the borders of the continent. Specifically, we ask in this review whether open Marantaceae forests and dense closed-canopy forests can be considered as one of the few documented examples of alternative stable states in tropical forests. First, we introduce the different ecological factors that have been posited to drive Marantaceae forests (climate, soil, historical and recent anthropogenic pressures, herbivores) and develop the different hypotheses that have been suggested to explain how Marantaceae forests establish in relation with other vegetation types (understory invasion, early succession after disturbance, and intermediate successional stage). Then, we review the underlying ecological mechanisms that can explain the stability of Marantaceae forests in the long term (tree recruitment inhibition, promotion of and resilience to fire, adaptive reproduction, maintenance by megaherbivores). Although some uncertainties remain and call for further empirical and theoretical research, we found converging evidence that Marantaceae forests are associated with an ecological succession that has been deflected or arrested. If verified, Marantaceae forests may provide a useful model to understand critical transitions in forest ecosystems, which is of particular relevance to achieve sustainable forest management and mitigate global climate change.

Resistance of African tropical forests to an extreme climate anomaly.

The responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015-2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle. The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements. African tropical forests may be particularly sensitive because they exist in relatively dry conditions compared with Amazonian or Asian forests, or they may be more resistant because of an abundance of drought-adapted species. Here, we report responses of structurally intact old-growth lowland tropical forests inventoried within the African Tropical Rainforest Observatory Network (AfriTRON). We use 100 long-term inventory plots from six countries each measured at least twice prior to and once following the 2015-2016 El Niño event. These plots experienced the highest temperatures and driest conditions on record. The record temperature did not significantly reduce carbon gains from tree growth or significantly increase carbon losses from tree mortality, but the record drought did significantly decrease net carbon uptake. Overall, the long-term biomass increase of these forests was reduced due to the El Niño event, but these plots remained a live biomass carbon sink (0.51 ± 0.40 Mg C ha-1 y-1) despite extreme environmental conditions. Our analyses, while limited to African tropical forests, suggest they may be more resistant to climatic extremes than Amazonian and Asian forests.

Early Secondary Alveolar Bone Grafting and Facial Growth of Patients with Complete Unilateral Cleft Lip and Palate.

OBJECTIVE: To investigate the craniofacial growth outcomes of early secondary alveolar bone grafting(ABG) around 6 years of age. DESIGN: Retrospective cohort study. SETTING: 1 North-American and 5 Northern-European cleft centers. SUBJECTS: 33 subjects with CUCLP consecutively treated with secondary ABG around 6 years of age were compared to 105 subjects from 4 centers treated with late secondary ABG and 19 subjects from 1 center with primary ABG. METHODS: Preorthodontic standardized lateral cephalometric radiographs taken after 12 years of age were traced and analyzed according to the Eurocleft Study protocol. Fourteen angular and two proportional measurements were performed. Measurement means from the Study Center(SC) were compared to 5 Northern-European centers using analysis of variance and Welch's modified t-tests, and P < .05 was considered statistically significant. RESULTS: For the SC, the mean age ± SD at the time of bone graft was 5.85 ± 0.71 years and the mean age at the time of the lateral cephalogram was 13.4 ± 1.8 years. The sagittal maxillary prominence of the SC was favorably comparable to the 5 Northern-European centers. The mean SNA (78.1 ± 4.3) for the SC was significantly higher compared to 4 of the 5 Northern-European centers(all P < .05), and the mean ANB angle was comparable to 4 of the 5 centers. Similarly, the mean soft tissue ANB angle was not significantly different to the 5 centers. The soft tissue vertical proportions compared favorably to all 5 Northern-European centers(all P < .01). CONCLUSIONS: Craniofacial growth outcomes of early secondary ABG around 6 years compare favorably to the outcomes of late secondary ABG.

Evaluating SWAG and Its Validity When Compared to 3D Imagery of Secondarily Grafted Cleft Sites.

OBJECTIVE: To test validity of 2D Standardized Way to Assess Grafts (SWAG) ratings to assess 3D outcomes of bone grafting (ABG). PATIENTS: 43 patients (34 UCLP, 9 BCLP) with non-syndromic complete clefts, bone-grafted at mean age 9yrs/3mos, with available post-graft occlusal radiographs and cone beam computed tomography (CBCT) (taken mean 4yrs/9mos post-ABG). MAIN OUTCOME MEASURES: 2D occlusal radiographs rated twice using SWAG by 6 calibrated raters. 12 scores were averaged and converted to a percentage reflecting bone-fill. Weighted Kappas were assessed for SWAG reliability. 3D cleft-site bone volume was calculated by 1 rater using ITK-SNAP. 13 cleft sites were re-measured by the 'one rater' for 3D reliability using Intraclass Correlation Coefficient (ICC). 2D versus 3D ratings were compared using paired t-test, independent samples t-test, Bland-Altman and Linear Regression. Significance level was P = .5. RESULTS: 2D reliability was 0.724 (intra-rater) and 0.546 (inter-rater). 3D reliability was 0.986. Bland-Altman plot comparing 2D vs 3D showed for 45 of 47 graft-sites were within 2 SD's. Mean % bone-fill was 64.11% with 2D and 69.06% with 3D (mean difference = 4.95%) that was a non-significant difference in both t-tests. Regression showed a statistically significant relation between the two methods (r2 = 0.46; P = .0001). CONCLUSION: 2D SWAG systematically and non-significantly underestimated bone-fill. There was a significant correlation between 2D/3D methods. Bland-Altman analysis illustrated the similarity of the two methods. For comparisons of group (cleft treatment Centers') bone grafting outcomes, the 2D method may suffice as a proxy for the 3D method. However, with individual variation up to 40% in 2D estimates of actual 3D volume, 2D SWAG method cannot be used in place of 3D images.

Age-associated thin hair displays molecular, structural and mechanical characteristic changes.

Hair thinning occurs during normal chronological aging in women and in men leading to an increased level of thinner hair shafts alongside original thicker shafts. However, the characteristics of age-associated thin hairs remain largely unknown. Here we analyzed these characteristics by comparing at multiscale thin and thick hairs originated from Caucasian women older than 50 years. We observed that the cortex of thick hair contains many K35(+)/K38(-) keratinocytes that decrease in number with decreasing hair diameter. Accordingly, X-ray diffraction revealed differences supporting that thin and thick hairs are different with regards to the nature of the intermediate filaments making up their cortices. In addition, we observed a direct correlation between hair ellipticity and diameter with thin hairs having an unexpected round shape compared to the elliptic shape of thick hairs. We also observed fewer cuticle layers and a reduced frequency of a medullae in thin hairs. Regarding mechanical properties, thin hairs exhibited a surprising increased rigidity, a decrease of the viscosity and a decrease of the water diffusion coefficient. Hence, aged-associated thin hairs exhibit numerous modifications likely due to changes of hair differentiation program as evidenced by the modulations in the expression of hair keratins and keratin-associated proteins and by the X-ray diffraction specters. Hence, hair thinning with age does not consist simply of the production of a smaller hair. It is rather a more profound process likely relying on the implementation of an "aged hair program" that takes place within the hair follicle.

Tallo: A global tree allometry and crown architecture database.

Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research-from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non-forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC-BY 4.0 licence and can be access from: https://doi.org/10.5281/zenodo.6637599. To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology-from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle.

Hierarchical Superhydrophobic Device to Concentrate and Precisely Localize Water-Soluble Analytes: A Route to Environmental Analysis.

An efficient superhydrophobic concentrator is developed using a hierarchical superhydrophobic surface on which the evaporation of a sessile droplet (6 µL) drives the nonvolatile elements it contains on a predefined micrometric analytical surface (pedestal of 80 µm diameter). This hierarchical silicon surface exhibits a surface texture made of etched nanopillars and consists of micropillars and guiding lines, arranged in radial symmetry around the central pedestal. The guiding lines ensure the overall convergence of the sessile droplet toward the central pedestal during evaporation. The nanopillar texturing induced a delay in the Cassie-Baxter to Wenzel regime transition, until the edge of the droplet reaches the periphery of the pedestal. Experiments performed with polymer microparticles suspended in ultrapure water or with DNA molecules solubilized in ultrapure water at sub-fM concentrations demonstrated that the totality of the nonvolatile elements in the liquid microvolume is delivered on or close to the pedestal area, in a very reproducible manner. The very high concentration capacity of the device enabled the discrimination of the degree of purity of ultrapure water samples from different origins. The concentrator also turned out to be functional for raw water samples, opening possible applications to environmental analysis.

REview of potentially inappropriate MEDIcation pr[e]scribing in Seniors (REMEDI[e]S): French implicit and explicit criteria.

PURPOSE: To establish a consensus on both explicit and implicit criteria in order to identify potentially inappropriate prescribing (PIP) in French older people aged 75 years and over or 65 years and over with multimorbidity. METHODS: Fifteen experts in geriatrics, general practice, pharmacy, and clinical pharmacology were involved in a two-round Delphi survey to assess preliminary explicit and implicit criteria based on an extensive literature review and up-to-date evidence data. Experts were asked to rate their level of agreement using a 5-level Likert scale for inclusion of criteria and also for rationale and therapeutic alternatives. A consensus was considered as reached if at least 75% of the experts rated criteria as "strongly agreed" or "agreed." RESULTS: The new tool included a seven-step algorithm (implicit criteria) encompassing the three main domains that define PIP (i.e. overprescribing, underprescribing, and misprescribing) and 104 explicit criteria. Explicit criteria were divided into 6 tables related to inappropriate drug duplications (n = 7 criteria), omissions of medications and/or medication associations (n = 16), medications with an unfavourable benefit/risk ratio and/or a questionable efficacy (n = 39), medications with an unsuitable dose (n = 4) or duration (n = 6), drug-disease (n = 13), and drug-drug interactions (n = 19). CONCLUSION: The REMEDI[e]S tool (REview of potentially inappropriate MEDIcation pr[e]scribing in Seniors) is an original mixed tool, adapted to French medical practices, aimed at preventing PIP both at the individual level in clinical practice and the population level in large-scale studies. Therefore, its use could contribute to an improvement in healthcare professionals' prescribing practices and safer care in older adults.

The Effect of Earlier Bone Grafting, Prior to Orthodontic Treatment, on SWAG Ratings of Graft Outcomes.

OBJECTIVE: To compare the outcomes between 2 groups of patients with complete clefts treated with early secondary alveolar bone grafting (ABG) at 2 centers (5-7 years, before orthodontic intervention) and to a third group of patients treated at one of those centers (center 1) who had received later secondary ABG (8-10 years, after orthodontic intervention). DESIGN: Blind retrospective analysis of cleft site radiographs using Americleft Standardized Way to Assess Grafts (SWAG) scale. PATIENTS: A total of 99 patients with complete clefts from 2 North American cleft/craniofacial centers. INTERVENTIONS: Secondary ABG representing 2 protocols: early grafting at a mean age of 6.6 years prior to any orthodontic intervention, and later grafting at a mean age of 10.2 years following pregrafting orthodontic intervention. MAIN OUTCOME MEASURES: Using occlusal radiographs, the SWAG scale from 0 (failed graft) to 6 (ideal) was used. Six trained, calibrated raters scored each radiograph twice, with the average of the 2 ratings used as the final score. Reliability was assessed using the weighted κ statistic. The significance of differences between groups was determined using the Kruskal-Wallis test and Dunn test for pairwise comparisons. RESULTS: Inter-rater reliability of SWAG method was good (0.631). Intra-rater reliability was excellent (0.817). There was a tendency for improved total graft outcome in the early grafted group from center 1 compared to the later grafted group with improvement being significantly different in only the coronal third of the early, preorthodontic grafted group. However, the difference was not statistically significant for the graft overall.

[Prescribing inappropriate medication in the elderly: review of the main therapeutic scales]. / Prescription médicamenteuse inappropriée chez le sujet âgé : revue des principales échelles thérapeutiques.

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Population genomics of the widespread African savannah trees Afzelia africana and Afzelia quanzensis reveals no significant past fragmentation of their distribution ranges.

PREMISE: Few studies have addressed the evolutionary history of tree species from African savannahs. Afzelia contains economically important timber species, including two species widely distributed in African savannahs: A. africana in the Sudanian region and A. quanzensis in the Zambezian region. We aimed to infer whether these species underwent range fragmentation and/or demographic changes, possibly reflecting how savannahs responded to Quaternary climate changes. METHODS: We characterized the genetic diversity and structure of these species across their distribution ranges using nuclear microsatellites (SSRs) and genotyping-by-sequencing (GBS) markers. Six SSR loci were genotyped in 241 A. africana and 113 A. quanzensis individuals, while 2800 high-quality single nucleotide polymorphisms (SNPs) were identified in 30 A. africana individuals. RESULTS: Both species appeared to be mainly outcrossing. The kinship between individuals decayed with the logarithm of the distance at similar rates across species and markers, leading to relatively small Sp statistics (0.0056 for SSR and 0.0054 for SNP in A. africana, 0.0075 for SSR in A. quanzensis). The patterns were consistent with isolation by distance expectations in the absence of large-scale geographic gradients. Bayesian clustering of SSR genotypes did not detect genetic clusters within species. In contrast, SNP data resolved intraspecific genetic clusters in A. africana, illustrating the higher resolving power of GBS. However, these clusters revealed low levels of differentiation and no clear geographical entities, so that they were interpreted as resulting from the isolation by distance pattern rather than from past population fragmentation. CONCLUSIONS: These results suggest that populations have remained connected throughout the large, continuous savannah landscapes. The absence of clear phylogeographic discontinuities, also found in a few other African savannah trees, indicates that their distribution ranges have not been significantly fragmented during the climatic oscillations of the Pleistocene, in contrast to patterns commonly found in African rainforest trees.

Seed and pollen dispersal distances in two African legume timber trees and their reproductive potential under selective logging.

The natural regeneration of tree species depends on seed and pollen dispersal. To assess whether limited dispersal could be critical for the sustainability of selective logging practices, we performed parentage analyses in two Central African legume canopy species displaying contrasted floral and fruit traits: Distemonanthus benthamianus and Erythrophleum suaveolens. We also developed new tools linking forward dispersal kernels with backward migration rates to better characterize long-distance dispersal. Much longer pollen dispersal in D. benthamianus (mean distance dp  = 700 m, mp  = 52% immigration rate in 6 km2 plot, s = 7% selfing rate) than in E. suaveolens (dp  = 294 m, mp  = 22% in 2 km2 plot, s = 20%) might reflect different insect pollinators. At a local scale, secondary seed dispersal by vertebrates led to larger seed dispersal distances in the barochorous E. suaveolens (ds  = 175 m) than in the wind-dispersed D. benthamianus (ds  = 71 m). Yet, seed dispersal appeared much more fat-tailed in the latter species (15%-25% seeds dispersing >500 m), putatively due to storm winds (papery pods). The reproductive success was correlated to trunk diameter in E. suaveolens and crown dominance in D. benthamianus. Contrary to D. benthamianus, E. suaveolens underwent significant assortative mating, increasing further the already high inbreeding of its juveniles due to selfing, which seems offset by strong inbreeding depression. To achieve sustainable exploitation, seed and pollen dispersal distances did not appear limiting, but the natural regeneration of E. suaveolens might become insufficient if all trees above the minimum legal cutting diameter were exploited. This highlights the importance of assessing the diameter structure of reproductive trees for logged species.

VLITL is a major cross-ß-sheet signal for fibrinogen Aα-chain frameshift variants.

The first case of hereditary fibrinogen Aα-chain amyloidosis was recognized >20 years ago, but disease mechanisms still remain unknown. Here we report detailed clinical and proteomics studies of a French kindred with a novel amyloidogenic fibrinogen Aα-chain frameshift variant, Phe521Leufs, causing a severe familial form of renal amyloidosis. Next, we focused our investigations to elucidate the molecular basis that render this Aα-chain variant amyloidogenic. We show that a 49-mer peptide derived from the C-terminal part of the Phe521Leufs chain is deposited as fibrils in the patient's kidneys, establishing that only a small portion of Phe521Leufs directly contributes to amyloid formation in vivo. In silico analysis indicated that this 49-mer Aα-chain peptide contained a motif (VLITL), with a high intrinsic propensity for ß-aggregation at residues 44 to 48 of human renal fibrils. To experimentally verify the amyloid propensity of VLITL, we generated synthetic Phe521Leufs-derived peptides and compared their capacity for fibril formation in vitro with that of their VLITL-deleted counterparts. We show that VLITL forms typical amyloid fibrils in vitro and is a major signal for cross-ß-sheet self-association of the 49-mer Phe521Leufs peptide identified in vivo, whereas its absence abrogates fibril formation. This study provides compelling evidence that VLITL confers amyloidogenic properties to Aα-chain frameshift variants, yielding a previously unknown molecular basis for the pathogenesis of Aα-chain amyloidosis.

Keratin network modifications lead to the mechanical stiffening of the hair follicle fiber.

The complex mechanical properties of biomaterials such as hair, horn, skin, or bone are determined by the architecture of the underlying fibrous bionetworks. Although much is known about the influence of the cytoskeleton on the mechanics of isolated cells, this has been less studied in tridimensional tissues. We used the hair follicle as a model to link changes in the keratin network composition and architecture to the mechanical properties of the nascent hair. We show using atomic force microscopy that the soft keratinocyte matrix at the base of the follicle stiffens by a factor of ∼360, from 30 kPa to 11 MPa along the first millimeter of the follicle. The early mechanical stiffening is concomitant to an increase in diameter of the keratin macrofibrils, their continuous compaction, and increasingly parallel orientation. The related stiffening of the material follows a power law, typical of the mechanics of nonthermal bending-dominated fiber networks. In addition, we used X-ray diffraction to monitor changes in the (supra)molecular organization within the keratin fibers. At later keratinization stages, the inner mechanical properties of the macrofibrils dominate the stiffening due to the progressive setting up of the cystine network. Our findings corroborate existing models on the sequence of biological and structural events during hair keratinization.

Facial Growth of Patients With Complete Unilateral Cleft Lip and Palate Treated With Alveolar Bone Grafting at 6 Years.

OBJECTIVE: To investigate the effect that alveolar bone grafting (ABG) around 6 years of age has on facial growth by assessing craniofacial growth outcomes. DESIGN: Retrospective cohort study. SETTING: North American cleft centers. PARTICIPANTS: A total of 33 children with complete unilateral cleft lip and palate who were consecutively treated with secondary ABG around 6 years of age were compared to 148 participants from 4 centers with late secondary ABG. METHODS: Preorthodontic standardized lateral cephalometric radiographs were analyzed and traced according to the Americleft Study protocol. Sixteen angular and 2 proportional measurements were performed. The outcomes of all ABG were assessed using the Standardized Way to Assess Graft scale. Measurement means from the study center (SC) were compared to 4 North American centers using analysis of variance and Welch modified t tests, and P < .05 was considered statistically significant. RESULTS: For the SC, the mean age (SD) at the time of bone graft was 5.85 (0.71) years and the mean age at the time of the lateral cephalogram was 13.4 (1.8) years. The sagittal maxillary prominence of the SC was comparable to the 4 other centers. The mean SNA (78.1 [4.3]) for the SC was significantly higher compared to one center that used primary bone grafting ( P = .03). The soft tissue mean ANB (3.52 [4.09]) for the SC was significantly lower compared to 3 of the centers. CONCLUSIONS: Early secondary ABG around 6 years of age did not result in reduced midface projection as assessed by SNA and thus did not compromise anterior maxillary growth.

[Geriatrics and e-technology in an institution]. / Gériatrie et e-technologie en Ehpad.

The objective of the GER-e-TEC™ project is to provide a personalised medical follow-up of residents in nursing homes with the aid of a telemedicine intelligent platform. It will assist the nursing staff by automatically processing information obtained from sensors and questionnaires in order to give an early warning about high-risk situations. This telemedicine tool will enable health professionals to optimise residents' care.

Evolution in the Amphi-Atlantic tropical genus Guibourtia (Fabaceae, Detarioideae), combining NGS phylogeny and morphology.

Tropical rain forests support a remarkable diversity of tree species, questioning how and when this diversity arose. The genus Guibourtia (Fabaceae, Detarioideae), characterized by two South American and 13 African tree species growing in various tropical biomes, is an interesting model to address the role of biogeographic processes and adaptation to contrasted environments on species diversification. Combining whole plastid genome sequencing and morphological characters analysis, we studied the timing of speciation and diversification processes in Guibourtia through molecular dating and ancestral habitats reconstruction. All species except G. demeusei and G. copallifera appear monophyletic. Dispersal from Africa to America across the Atlantic Ocean is the most plausible hypothesis to explain the occurrence of Neotropical Guibourtia species, which diverged ca. 11.8 Ma from their closest African relatives. The diversification of the three main clades of African Guibourtia is concomitant to Miocene global climate changes, highlighting pre-Quaternary speciation events. These clades differ by their reproductive characters, which validates the three subgenera previously described: Pseudocopaiva, Guibourtia and Gorskia. Within most monophyletic species, plastid lineages start diverging from each other during the Pliocene or early Pleistocene, suggesting that these species already arose during this period. The multiple transitions between rain forests and dry forests/savannahs inferred here through the plastid phylogeny in each Guibourtia subgenus address thus new questions about the role of phylogenetic relationships in shaping ecological niche and morphological similarity among taxa.

Liquid crystal-based tunable photodetector operating in the telecom C-band.

Liquid crystal (LC) microcells monolithically integrated on the surface of InGaAs based photodiodes (PDs) are demonstrated. These LC microcells acting as tunable Fabry-Perot filters exhibit a wavelength tunability of more than 100 nm around 1550 nm with less than 10V applied voltage. Using a tunable laser operating in the S and C bands, photocurrent measurements are performed. On a 70 nm tuning range covered with a driving voltage lower than 7V, the average sensitivity for the PD is 0.4 A/W and the spectral linewidth of the LC filter remains constant, showing a FWHM of 1.5 nm. Finally, the emission spectrum from an Er-doped fiber is acquired by using this tunable PD as a micro-spectrometer.