High-resolution SAR images for fire susceptibility estimation in urban forestry

We present an adaptive system for the automatic assessment of both physical and anthropic fire impact factors on periurban forestries. The aim is to provide an integrated methodology exploiting a complex data structure built upon a multi resolution grid gathering historical land exploitation and meteorological data, records of human habits together with suitably segmented and interpreted high resolution X-SAR images, and several other information sources. The contribution of the model and its novelty rely mainly on the definition of a learning schema lifting different factors and aspects of fire causes, including physical, social and behavioural ones, to the design of a fire susceptibility map, of a specific urban forestry. The outcome is an integrated geospatial database providing an infrastructure that merges cartography, heterogeneous data and complex analysis, in so establishing a digital environment where users and tools are interactively connected in an efficient and flexible way

High field MR microimaging investigation gives more insights on spongy bone characteristics

Spongy-bone is a porous system characterized by a solid trabecular network immersed in bonemarrow and characterized by a different relative percentage of water and fats. In our previous paper, we demonstrated using calf bone samples, that water is more prevalent in the boundary zone while fats are rearranged primarily in the central zone of each pore. Moreover we showed that water internal gradient (Gi) magnitude from the samples was directly proportional to their trabecular bone density. Using a 9.4T MR micro-imaging system, here we evaluated T2, T2*, apparent diffusion coefficient (ADC) and Gi parameters from in vitro calf samples in spatially resolved modality, for both water and fat components. Moreover, relative percentages of water and fats were quantified from spectra. T2, T2* and ADC values are higher in fat than in water component. Moreover, the differential effects of fat and water diffusion result in different T2 and Gi behaviours. Our results suggest that differently from fat parameters, water T2*, ADC and Gi, may be reliable markers to assess not only trabecular bone density but, more generally, the status of spongy bone

How can I help thy Husband's copying Me? : Dante tra Blake, Füssli e Flaxman

Non sempre è stata rivolta sufficiente attenzione al fatto che i tre più grandi interpreti figurativi della Commedia nell'Inghilterra tra Sette e Ottocento - Johann Heinrich Füssli (1741-1825), John Flaxman (1755-1826) e William Blake (1757-1827) - fossero in stretto contatto tra loro e reciprocamente legati da un solido e durevole vincolo di amicizia. Le illustrazioni dantesche di Blake vengono analizzate alla luce di questo dato fondamentale, ricostruendo le vicende biografiche che caratterizzarono l'amicizia fra i tre artisti e valutando le possibili influenze reciproche all'interno della loro produzione dantesca.No sempre s'ha fet suficient atenció al fet que els tres més grans intèrprets figuratius de la Comèdia a l'Anglaterra dels segles XVIII i XIX - Johann Heinrich Füssli (1741-1825), John Flaxman (1755-1826) i William Blake (1757-1827) - tenien contacte pròxim i estaven mútuament units per un sòlid i persistent vincle d'amistat. Les il·lustracions dantesques de Blake s'analitzen tenint en compte aquest fet fonamental, reconstruint els esdeveniments biogràfics que van caracteritzar l'amistat entre els tres artistes i avaluant les possibles influències recíproques dins de la seva producció dantesca.That the three greatest interpreters of Dante's Commedia between the 18th and the 19th century England - Johann Heinrich Füssli (1741-1825), John Flaxman (1755-1826) and William Blake (1757-1827) - were in close contact and reciprocally linked by a solid and lifelong bond of friendship, is a fact which has not always received enough scholarly attention. Blake's Dante illustrations are here analyzed in the light of this fundamental occurrence, reconstructing the biographical events which characterized the friendship between the three artists and considering the possible reciprocal influence within their Dantesque production.No siempre se ha prestado suficiente atención al hecho de que los tres más grandes intérpretes figurativos de la Comedia en la Inglaterra de los siglos XVIII y XIX - Johann Heinrich Füssli (1741-1825), John Flaxman (1755-1826) y William Blake (1757-1827) - tenían contacto cercano y estaban mutuamente unidos por un sólido y persistente vínculo de amistad. Las ilustraciones dantescas de Blake se analizan teniendo en cuenta este hecho fundamental, reconstruyendo los acontecimientos biográficos que caracterizaron la amistad entre los tres artistas y evaluando las posibles influencias recíprocas dentro de su producción dantesca

Direct conversion of human pluripotent stem cells into cranial motor neurons using a piggyBac vector

Human pluripotent stem cells (PSCs) are widely used for in vitro disease modeling. One of the challenges in the field is represented by the ability of converting human PSCs into specific disease-relevant cell types. The nervous system is composed of a wide variety of neuronal types with selective vulnerability in neurodegenerative diseases. This is particularly relevant for motor neuron diseases, in which different motor neurons populations show a different susceptibility to degeneration. Here we developed a fast and efficient method to convert human induced Pluripotent Stem Cells into cranial motor neurons of the branchiomotor and visceral motor subtype. These populations represent the motor neuron subgroup that is primarily affected by a severe form of amyotrophic lateral sclerosis with bulbar onset and worst prognosis. This goal was achieved by stable integration of an inducible vector, based on the piggyBac transposon, allowing controlled activation of Ngn2, Isl1 and Phox2a (NIP). The NIP module effectively produced electrophysiologically active cranial motor neurons. Our method can be easily extended to PSCs carrying disease-associated mutations, thus providing a useful tool to shed light on the cellular and molecular bases of selective motor neuron vulnerability in pathological conditions

Including diffusion time dependence in the extra-axonal space improves in vivo estimates of axonal diameter and density in human white matter

Axonal density and diameter are two fundamental properties of brain white matter. Recently, advanced diffusion MRI techniques have made these two parameters accessible in vivo. However, the techniques available to estimate such parameters are still under development. For example, current methods to map axonal diameters capture relative trends over different structures, but consistently over-estimate absolute diameters. Axonal density estimates are more accessible experimentally, but different modeling approaches exist and the impact of the experimental parameters has not been thoroughly quantified, potentially leading to incompatibility of results obtained in different studies using different techniques. Here, we characterise the impact of diffusion time on axonal density and diameter estimates using Monte Carlo simulations and STEAM diffusion MRI at 7 T on 9 healthy volunteers. We show that axonal density and diameter estimates strongly depend on diffusion time, with diameters almost invariably overestimated and density both over and underestimated for some commonly used models. Crucially, we also demonstrate that these biases are reduced when the model accounts for diffusion time dependency in the extra-axonal space. For axonal density estimates, both upward and downward bias in different situations are removed by modeling extra-axonal time-dependence, showing increased accuracy in these estimates. For axonal diameter estimates, we report increased accuracy in ground truth simulations and axonal diameter estimates decreased away from high values given by earlier models and towards known values in the human corpus callosum when modeling extra-axonal time-dependence. Axonal diameter feasibility under both advanced and clinical settings is discussed in the light of the proposed advances

Multi-scale theoretical approach to X-ray absorption spectra in disordered systems: an application to the study of Zn(II) in water

We develop a multi-scale theoretical approach aimed at calculating from first principles X-ray absorption spectra of liquid solutions and disordered systems. We test the method by considering the paradigmatic case of Zn(II) in water which, besides being relevant in itself, is also of interest for biology. With the help of classical molecular dynamics simulations we start by producing bunches of configurations differing for the Zn(II)-water coordination mode. Different coordination modes are obtained by making use of the so-called dummy atoms method. From the collected molecular dynamics trajectories, snapshots of a more manageable subsystem encompassing the metal site and two solvation layers are cut out. Density functional theory is used to optimize and relax these reduced system configurations employing a uniform dielectric to mimic the surrounding bulk liquid water. On the resulting structures, fully quantum mechanical X-ray absorption spectra calculations are performed by including core-hole effects and core-level shifts. The proposed approach does not rely on any guessing or fitting of the force field or of the atomic positions of the system. The comparison of the theoretically computed spectrum with the experimental Zn K-edge XANES data unambiguously demonstrates that among the different a priori possible geometries, Zn(II) in water lives in an octahedral coordination mode.Comment: 8 pages, 3 figure

Why diffusion tensor MRI does well only some of the time: Variance and covariance of white matter tissue microstructure attributes in the living human brain

Fundamental to increasing our understanding of the role of white matter microstructure in normal/abnormal function in the living human is the development of MR-based metrics that provide increased specificity to distinct attributes of the white matter (e.g., local fibre architecture, axon morphology, and myelin content). In recent years, different approaches have been developed to enhance this specificity, and the Tractometry framework was introduced to combine the resulting multi-parametric data for a comprehensive assessment of white matter properties. The present work exploits that framework to characterise the statistical properties, specifically the variance and covariance, of these advanced microstructural indices across the major white matter pathways, with the aim of giving clear indications on the preferred metric(s) given the specific research question. A cohort of healthy subjects was scanned with a protocol that combined multi-component relaxometry with conventional and advanced diffusion MRI acquisitions to build the first comprehensive MRI atlas of white matter microstructure. The mean and standard deviation of the different metrics were analysed in order to understand how they vary across different brain regions/individuals and the correlation between them. Characterising the fibre architectural complexity (in terms of number of fibre populations in a voxel) provides clear insights into correlation/lack of correlation between the different metrics and explains why DT-MRI is a good model for white matter only some of the time. The study also identifies the metrics that account for the largest inter-subject variability and reports the minimal sample size required to detect differences in means, showing that, on the other hand, conventional DT-MRI indices might still be the safest choice in many contexts

T1 relaxometry of crossing fibres in the human brain

A comprehensive tract-based characterisation of white matter should include the ability to quantify myelin and axonal attributes irrespective of the complexity of fibre organisation within the voxel. Recently, a new experimental framework that combines inversion recovery and diffusion MRI, called inversion recovery diffusion tensor imaging (IR-DTI), was introduced and applied in an animal study. IR-DTI provides the ability to assign to each unique fibre population within a voxel a specific value of the longitudinal relaxation time, T1, which is a proxy for myelin content. Here, we apply the IR-DTI approach to the human brain in vivo on 7 healthy subjects for the first time. We demonstrate that the approach is able to measure differential tract properties in crossing fibre areas, reflecting the different myelination of tracts. We also show that tract-specific T1 has less inter-subject variability compared to conventional T1 in areas of crossing fibres, suggesting increased specificity to distinct fibre populations. Finally we show in simulations that changes in myelination selectively affecting one fibre bundle in crossing fibre areas can potentially be detected earlier using IR-DTI

Epigenetic control of EMT/MET dynamics: HNF4α impacts DNMT3s through miRs-29

Background and aims: Epithelial-to-mesenchymal transition (EMT) and the reverse mesenchymal-to-epithelial transition (MET) are manifestations of cellular plasticity that imply a dynamic and profound gene expression reprogramming. While a major epigenetic code controlling the coordinated regulation of a whole transcriptional profile is guaranteed by DNA methylation, DNA methyltransferase (DNMT) activities in EMT/MET dynamics are still largely unexplored. Here, we investigated the molecular mechanisms directly linking HNF4α, the master effector of MET, to the regulation of both de novo of DNMT 3A and 3B. Methods: Correlation among EMT/MET markers, microRNA29 and DNMT3s expression was evaluated by RT-qPCR, Western blotting and immunocytochemical analysis. Functional roles of microRNAs and DNMT3s were tested by anti-miRs, microRNA precursors and chemical inhibitors. ChIP was utilized for investigating HNF4α DNA binding activity. Results: HNF4α silencing was sufficient to induce positive modulation of DNMT3B, in in vitro differentiated hepatocytes as well as in vivo hepatocyte-specific Hnf4α knockout mice, and DNMT3A, in vitro, but not DNMT1. In exploring the molecular mechanisms underlying these observations, evidence have been gathered for (i) the inverse correlation between DNMT3 levels and the expression of their regulators miR-29a and miR- 29b and (ii) the role of HNF4α as a direct regulator of miR-29a-b transcription. Notably, during TGFβ-induced EMT, DNMT3s' pivotal function has been proved, thus suggesting the need for the repression of these DNMTs in the maintenance of a differentiated phenotype. Conclusions: HNF4α maintains hepatocyte identity by regulating miR-29a and -29b expression, which in turn control epigenetic modifications by limiting DNMT3A and DNMT3B levels