Acoustic, thermal and flow processes in a water filled nanoporous glasses by time-resolved optical spectroscopy

We present heterodyne detected transient grating measurements on water filled Vycor 7930 in the range of temperature 20 - 90 degrees C. This experimental investigation enables to measure the acoustic propagation, the average density variation due the liquid flow and the thermal diffusion in this water filled nano-porous material. The data have been analyzed with the model of Pecker and Deresiewicz which is an extension of Biot model to account for the thermal effects. In the whole temperature range the data are qualitatively described by this hydrodynamic model that enables a meaningful insight of the different dynamic phenomena. The data analysis proves that the signal in the intermediate and long time-scale can be mainly addressed to the water dynamics inside the pores. We proved the existence of a peculiar interplay between the mass and the heat transport that produces a flow and back-flow process inside the nano-pores. During this process the solid and liquid dynamics have opposite phase as predicted by the Biot theory for the slow diffusive wave. Nevertheless, our experimental results confirm that transport of elastic energy (i.e. acoustic propagation), heat (i.e. thermal diffusion) and mass (i.e. liquid flow) in a liquid filled porous glass can be described according to hydrodynamic laws in spite of nanometric dimension of the pores. The data fitting, based on the hydrodynamic model, enables the extraction of several parameters of the water-Vycor system, even if some discrepancies appear when they are compared with values reported in the literature.Comment: 32 pages, 11 figure

Fast Analysis of Stop-Band FSS Integrated with Phased Array Antennas

This paper presents a method for the efficient analysis of multilayer frequency selective surfaces (FSSs) integrated with phased array of open-ended waveguides. The method is based on the assumption that all the periodic surfaces are arranged on the same spatial lattice (of arbitrary shape). The whole structure is represented as an equivalent multi-mode transmission line network, where each interface is characterized by an equivalent Generalized Scattering Matrix (GSM), computed through a fullwave analysis. To reduce the computational effort of the analysis a fast adaptive interpolation algorithm for the scattering matrix entries is included

NGS applications to understand invertebrate biodiversity of Antarctica and mechanisms of gene expression involved in climatic changes

Human activities, such as greenhouse emissions and pollution, are leading to global warming, environmental changes and biodiversity reduction. Pristine environments such as those of Antarctica are not immune to these phenomena, as is noticeable from the temperature shifts and ice-melting registered within the continent in recent decades. To date, many scientists focused on how marine species react to these changes but no molecular data are currently available for continental terrestrial invertebrates and in particular for Collembola (=springtails). Therefore, part of my PhD project was to study the transcriptomic response of the endemic Antarctic springtail Cryptopygus terranovus following a mid-term exposure of 20 days at 18°C. Expression data were compared with wild specimens sampled in native environment. Although individual plasticity in transcript modulation was recorded, several pathways appear to be differentially modulated: protein catabolism, fatty acid metabolism and a sexual response characterized by spermatid development were induced, while lipid catabolism was downregulated in treated samples. Moreover, the temperature experienced by these micro-invertebrates is a pivotal parameter to understand these animals' ecology and physiology. However, at present, detailed knowledge of microhabitat physical conditions in Antarctica is limited and biased towards sub-Antarctic and maritime Antarctic regions. To better understand these temperature conditions, it was analysed a year-round temperature data in ponds and soils in an area of the Victoria Land coast, comparing these measurements with air temperatures from the closest automatic weather station. Important difference in temperature dynamics between the air, soil and pond datasets was registered. Ponds were the warmest sites overall, mostly differing with the air temperatures due to their greater thermal capacity, which also influenced their patterns of freeze-thaw cycles and mean daily thermal excursion. Furthermore, to better understand the biodiversity of Collembola two new mitochondrial genomes of Antarctic springtails were sequenced and analysed. They were employed to revise the entire systematic of the class, its nucleotide composition and genome arrangement by comparing them to all the available sequences deposited in Genbank. In the phylogenetic analysis, with minor exceptions, it was confirmed the monophyly of Poduromorpha and Symphypleona sensu stricto (the latter recovered as the most basal group in the springtail phylogenetic tree), whereas monophyly of Neelipleona and Entomobryomorpha was only supported when some critical taxa in these two lineages were excluded. The genome arrangement review allowed to identify four new gene orders (one from the newly sequenced Tullbergia mixta), for a total of 16 models. Finally, nucleotide composition analyses confirmed the low AT bias in Collembola mitochondrial DNA respect to other Hexapoda, and that third codon position is inclined to mutation accumulation, especially in 4-fold amino-amino acids. To ease the process of mitochondrial genome analyses, it was created a web resource named EZmito, a free web server useful to analyse mitochondrial genomes. It is composed of five main tools: (i) EZsplit, useful to download and format sequences directly from the NCBI database; (ii) EZpipe, a pipeline designed to format mitochondrial sequences before the phylogenetic analysis; (iii) EZskew, which helps users to calculate nucleotide biases; (iv) EZcodon, a fast tool which calculates the Relative Synonym Codon Usage of different mtDNA species and (v) EZmix, which recognizes areas of inter molecular similarity indicative of the assembly of chimeric mitochondrial genomes. Interestingly, to date, the most used tool within the hub is EZcodon, followed by EZsplit and EZpipe

L’esprit « national » des villes communales des États Pontificaux à la fin du Moyen Âge. Le cas de Bologne

L’émergence d’une culture civique collective, d’une identité culturelle unitaire qui nait autour de la configuration politique urbaine, a été plusieurs fois mise en évidence dans le contexte des villes communales italiennes. À cette émergence, l’historiographie a souvent associé un processus de formation culturelle qui se rapproche de celui de la création d’un sentiment identitaire national : la coniuratio, moment créateur du principe associatif, qui a été définie comme le « mythe fondateur »..

One Dimensional Polymeric Organic Photonic Crystals for DFB Lasers

We present a very simple method to realize a one-dimensional photonic crystal (1D PC), consisting of a dye-doped polymeric multilayer. Due to the high photonic density of states at the edges of the photonic band-gap (PBG), a surface emitting distributed feedback (DFB) laser is obtained with this structure. Furthermore, the incidence angle dependence of the PBG of the polymeric multilayer is reported

The mitogenome of the jumping bristletail Trigoniophthalmus alternatus (Insecta, Microcoryphia) and the phylogeny of insect early-divergent lineages

The complete mitochondrial genome of the machilid Trigoniophthalmus alternatus (Silvestri 1904) is herein described and applied to phylogenetic analyses, inclusive of the most early-divergent lineages of hexapods. Both gene content and order generally conform with the organization of the arthropods’ mitochondrial genome. One gene translocation involving trnA is the autapomorphic character observed in this species. Another peculiar molecular feature is the long size of the A + T-rich region, due to the occurrence of repeat units. The phylogenetic analyses support the typical placement, along the hexapods’ tree, of Ectognatha, Monocondylia and Dicondylia, with Diplura as the adelphotaxon of all true insects

The mitochondrial genome of the springtail Bourletiella arvalis (Symphypleona, Collembola)

The complete mitochondrial genome of the springtail Bourletiella arvalis (Fitch, 1863) is herein described and applied to a Bayesian phylogenetic analysis, inclusive of all the Collembola mitochon- drial DNAs sequenced so far. The gene content and order, as well as the nucleotide composition, con- form with the well-known features of hexapods’ mitochondrial genomes. The phylogenetic analysis supports the monophyly of Collembola, Poduromorpha, Entomobryomorpha and Symphypleona. However, no mtDNA from Neelipleona is available to date, therefore limiting the application of mito- chondrial genomes to further investigate springtail systematics

tuning optical properties of opal photonic crystals by structural defects engineering

We report on the preparation and optical characterization of three dimensional colloidal photonic crystal (PhC) containing an engineered planar defect embedding photoactive push-pull dyes. Free standing polystyrene films having thickness between 0.6 and 3 microns doped with different dipolar chromophores were prepared. These films were sandwiched between two artificial opals creating a PhC structure with planar defect. The system was characterized by reflectance at normal incidence angle (R), variable angle transmittance (T), and photoluminescence spectroscopy (PL). Clear evidence of defect states were observed in T and R spectra, which allow the light to propagate for selected frequencies within the pseudogap (stop band)