Peculiar tension wood structure in Laetia procera (Poepp.) Eichl. (Flacourtiaceae)

International audienceTension wood of Laetia procera (Poepp.) Eichl. (Flacourtiaceae), a neo-tropical forest species, shows a peculiar secondary wall structure, with an alternance of thick and thin layers, while opposite wood of this species has a typical secondary wall structure (S1 + S2 + S3). Samples for the study of microstructural properties were collected upon the estimation of growth stresses in the living tree, in order to analyze the correlation of the former with the latter. Investigation using optical microscopy, scanning electron microscopy and UV microspectrophotometry allowed the description of the anatomy, ultra-structure and chemistry of this peculiar polylaminate secondary wall. In the thick layers, cellulose microfibril angle is very low (i.e., microfibril orientation is close to fibre axis) and cellulose microfibrils are well organized and parallel to each other. In the thin layers, microfibrils (only observable in the inner layer) are less organized and are oriented with a large angle relative to the axis of the cell. Thick layers are lightly lignified although thin layers show a higher content of lignin, close to that of opposite wood secondary wall. The more the wood was under tensile stress, the less the secondary wall was lignified, and lower the syringyl on guaiacyl lignin units' ratio was. The innermost layer of the secondary wall looks like a typical S3 layer with large microfibril angle and lignin occurrence. The interest of this kind of structure for the understanding of stress generation is discussed

Geochemistry of cumulates from the Bjerkreim-Sokndal layered intrusion (S. Norway). Part II. REE and the trapped liquid fraction

Rare earth elements in bulk cumulates and in separated minerals (plagioclase, apatite, Ca-poor and Ca-rich pyroxenes, ilmenite and magnetite) from the Bjerkreim-Sokndal layered intrusion (Rogaland Anorthosite Province, SW Norway) are investigated to better define the proportion of trapped liquid and its influence on bulk cumulate composition. In leuconoritic rocks (made up of plagioclase, Ca-poor pyroxene, ilmenite, magnetite, olivine), where apatite is an intercumulus phase, even a small fraction of trapped liquid significantly affects the REE pattern of the bulk cumulate, together with cumulus minerals proportion and composition. Contrastingly, in gabbronoritic cumulates characterized by the presence of cumulus Ca-rich pyroxene and apatite, cumulus apatite buffers the REE content. La/Sm and Eu/Eu* VS. P2O2 variations in leuconorites display mixing trends between a pure adcumulate and the composition of the trapped liquid, assumed to be similar to the parental magma. Assessment of the trapped liquid fraction in leuconorites ranges from 2 to 25% and is systematically higher in the north-eastern part of the intrusion. The likely reason for this wide range of TLF is different cooling rates in different parts of the intrusion depending on the distance to the gneissic margins. The REE patterns of liquids in equilibrium with primitive cumulates are calculated with mass balance equations. Major elements modelling (Duchesne, J.C., Charlier, B., 2005. Geochemistry of cumulates from the Bjerkreiin-Sokndal layered intrusion (S. Norway): Part I. Constraints from major elements on the mechanism of cumulate formation and on the jotunite liquid line of descent. Lithos. 83, 299-254) permits calculation of the REE content of melt in equilibrium with gabbronorites. Partition coefficients for REE between cumulus minerals and a jotunitic liquid are then calculated. Calculated liquids from the most primitive cumulates are similar to a primitive jotunite representing the parental magma of the intrusion, taking into account the trapped liquid fraction calculated from the P2O5 content. Consistent results demonstrate the reliability of liquid compositions calculated from bulk cumulates and confirm the hypothesis that the trapped liquid has crystallized as a closed-system without subsequent mobility of REE in a migrating interstitial liquid. (c) 2005 Elsevier B.V. All rights reserved

Gravitational Interactions of integrable models

We couple non-linear $\sigma$-models to Liouville gravity, showing that integrability properties of symmetric space models still hold for the matter sector. Using similar arguments for the fermionic counterpart, namely Gross--Neveu-type models, we verify that such conclusions must also hold for them, as recently suggested.Comment: 8 pages, final version to appear in Physics Letters B Revised version, with misprints corrected and some references adde

Gamma Knife Radiosurgery to Four Brainstem Lesions After Whole Brain Radiation Therapy

Our patient was a 58-year-old female with a history of extensive stage small cell lung cancer initially diagnosed in November 2018. She received palliative radiation to the right hip and whole brain in December of 2018 and then received chemotherapy. Unfortunately, in October 2019, the repeat brain magnetic resonance imaging (MRI) showed recurrent lesions and she was referred for Gamma Knife Radiosurgery (GKRS). At the time of the treatment, she was found to have four brainstem lesions as well as a left frontal lobe and a right frontal lobe lesion. She completed GKRS to all six lesions without any neurological complications seen in her short-term follow-up. This case report adds to the growing body of literature showing safety of GKRS for multiple brainstem lesions

Identification of anisotropic vibrational properties of Padauk wood with interlocked grain

International audienceGrain deviations and high extractives content are common features of many tropical woods. We aimed at clarifying their respective impact on vibrational properties, referring to African Padauk (Pterocarpus soyauxii Taub.), a species selected for its interlocked grain, high extractives content, and uses in xylophones. Specimens were cut parallel to the trunk axis (L), and local variations in grain angle (GA), microfibril angle (MFA), specific Young's modulus (E'L/ρ, where r stands for specific gravity) and damping coefficient (tanδL), were measured. GA dependence was analyzed by a mechanical model which allowed to identify the specific Young's modulus (E'3/ρ) and shear modulus (G'/ρ) along the grain (3), as well as their corresponding damping coefficients (tanδ3, tanδG). This analysis was done for native and then for extracted wood. Interlocked grain resulted in 0-25° GA and in variations of a factor 2 in E'L/ρ and tanδL. Along the grain, Padauk wood was characterized, as compared to typical hardwoods, by a somewhat lower E'3/ρ and elastic anisotropy (E'/G'), due to a wide microfibril angle plus a small weight effect of extracts; and a very low tanδ3 and moderate damping anisotropy (tanδG/tanδ3). Extraction affected mechanical parameters in the order: tanδ3 ≈ tanδG > G'/ρ >> E'3/ρ. That is, extractives' effects were nearly isotropic on damping but clearly anisotropic on storage moduli

The decreasing radial wood stiffness pattern of some tropical trees growing in the primary forest is reversed and increases when they are grown in a plantation

International audienceBackground : This study examines the radial trend in wood stiffness of tropical rainforest trees. The objective was to determine if the type of growing environment (exposed plantation or dense primary forest) would have an effect on this radial trend. Methods : The axial elastic modulus of wood samples, representing a pith to bark cross-section, of six trees from several French Guianese species (two of Eperua falcata, one of Eperua grandiflora, two of Carapa procera and one of Symphonia gloubulifera) was measured using a dynamic "forced vibration" method. Results : Primary forest trees were observed to have a decrease in wood stiffness from pith to bark, whereas plantation trees, from the same genus or species, displayed a corresponding increase in wood stiffness. Juvenile wood stiffness appears to vary depending on the environment in which the tree had grown. Conclusion : We suggest that the growth strategy of primary forest trees is to produce wood resistant to selfbuckling so that the height of the canopy may be obtained with the maximum of efficiency. In contrast, the growth strategy of the trees growing in an exposed plantation is to produce low-stiffness wood, important to provide flexibility in wind. Further experiments to study the behaviour of more species, with more individuals per species, growing across a range of physical environments, are required

Even Between-Lap Pacing Despite High Within-Lap Variation During Mountain Biking

Purpose: Given the paucity of research on pacing strategies during competitive events, this study examined changes in dynamic high-resolution performance parameters to analyze pacing profiles during a multiple-lap mountain-bike race over variable terrain. Methods: A global-positioning-system (GPS) unit (Garmin, Edge 305, USA) recorded velocity (m/s), distance (m), elevation (m), and heart rate at 1 Hz from 6 mountain-bike riders (mean ± SD age = 27.2 ± 5.0 y, stature = 176.8 ± 8.1 cm, mass = 76.3 ± 11.7 kg, VO2max = 55.1 ± 6.0 mL · kg–1 . min–1) competing in a multilap race. Lap-by-lap (interlap) pacing was analyzed using a 1-way ANOVA for mean time and mean velocity. Velocity data were averaged every 100 m and plotted against race distance and elevation to observe the presence of intralap variation. Results: There was no significant difference in lap times (P = .99) or lap velocity (P = .65) across the 5 laps. Within each lap, a high degree of oscillation in velocity was observed, which broadly reflected changes in terrain, but high-resolution data demonstrated additional nonmonotonic variation not related to terrain. Conclusion: Participants adopted an even pace strategy across the 5 laps despite rapid adjustments in velocity during each lap. While topographical and technical variations of the course accounted for some of the variability in velocity, the additional rapid adjustments in velocity may be associated with dynamic regulation of self-paced exercise

Building up spacetime with quantum entanglement

In this essay, we argue that the emergence of classically connected spacetimes is intimately related to the quantum entanglement of degrees of freedom in a non-perturbative description of quantum gravity. Disentangling the degrees of freedom associated with two regions of spacetime results in these regions pulling apart and pinching off from each other in a way that can be quantified by standard measures of entanglement.Comment: Gravity Research Foundation essay, 7 pages, LaTeX, 5 figure

Delivery of steric block morpholino oligomers by (R-X-R)4 peptides: structure–activity studies

Redirecting the splicing machinery through the hybridization of high affinity, RNase H- incompetent oligonucleotide analogs such as phosphoramidate morpholino oligonucleotides (PMO) might lead to important clinical applications. Chemical conjugation of PMO to arginine-rich cell penetrating peptides (CPP) such as (R-Ahx-R)4 (with Ahx standing for 6-aminohexanoic acid) leads to sequence-specific splicing correction in the absence of endosomolytic agents in cell culture at variance with most conventional CPPs. Importantly, (R-Ahx-R)4–PMO conjugates are effective in mouse models of various viral infections and Duchenne muscular dystrophy. Unfortunately, active doses in some applications might be close to cytotoxic ones thus presenting challenge for systemic administration of the conjugates in those clinical settings. Structure–activity relationship studies have thus been undertaken to unravel CPP structural features important for the efficient nuclear delivery of the conjugated PMO and limiting steps in their internalization pathway. Affinity for heparin (taken as a model heparan sulfate), hydrophobicity, cellular uptake, intracellular distribution and splicing correction have been monitored. Spacing between the charges, hydrophobicity of the linker between the Arg-groups and Arg-stereochemistry influence splicing correction efficiency. A significant correlation between splicing correction efficiency, affinity for heparin and ability to destabilize model synthetic vesicles has been observed but no correlation with cellular uptake has been found. Efforts will have to focus on endosomal escape since it appears to remain the limiting factor for the delivery of these splice-redirecting ON analogs

The apparent breastfeeding paradox in very preterm infants: relationship between breast feeding, early weight gain and neurodevelopment based on results from two cohorts, EPIPAGE and LIFT

Context: Supplementation of breast milk is difficult once infants suckle the breast and is often discontinued at end of hospitalisation and after discharge. Thus, breastfed preterm infants are exposed to an increased risk of nutritional deficit with a possible consequence on neurodevelopmental outcome. Objective: To assess the relationship between breast feeding at time of discharge, weight gain during hospitalisation and neurodevelopmental outcome. Design: Observational cohort study. Setting: Two large, independent population-based cohorts of very preterm infants: the Loire Infant Follow-up Team (LIFT) and the EPIPAGE cohorts. Patients: 2925 very preterm infants alive at discharge. Main outcome measure: Suboptimal neurodevelopmental outcome, defined as a score in the lower tercile, using Age and Stages Questionnaire at 2 years in LIFT and Kaufman Assessment Battery for Children Test at 5 years in EPIPAGE. Two propensity scores for breast feeding at discharge, one for each cohort, were used to reduce bias. Results: Breast feeding at time of discharge concerned only 278/1733 (16%) infants in LIFT and 409/2163 (19%) infants in EPIPAGE cohort. Breast feeding is significantly associated with an increased risk of losing one weight Z-score during hospitalisation (LIFT: n=1463, adjusted odd ratio (aOR)=2.51 (95% CI 1.87 to 3.36); EPIPAGE: n=1417, aOR=1.55 (95% CI 1.14 to 2.12)) and with a decreased risk for a suboptimal neurodevelopmental assessment (LIFT: n=1463, aOR=0.63 (95% CI 0.45 to 0.87); EPIPAGE: n=1441, aOR=0.65 (95% CI 0.47 to 0.89) and an increased chance of having a head circumference Z-score higher than 0.5 at 2 years in LIFT cohort (n=1276, aOR=1.43 (95% CI 1.02 to 2.02)) and at 5 years in EPIPAGE cohort (n=1412, aOR=1.47 (95% CI 1.10 to 1.95)). Conclusions: The observed better neurodevelopment in spite of suboptimal initial weight gain could be termed the 'apparent breastfeeding paradox' in very preterm infants. Regardless of the mechanisms involved, the current data provide encouragement for the use of breast feeding in preterm infants