Search results for "inversion"
showing 10 items of 312 documents
Chromosomal polymorphism and patterns of viability in natural populations of Drosophila melanogaster from cellar and vineyard.
1991
Two neighbouring natural populations of Drosophila melanogaster have been analysed, one from a cellar habitat and the other from a vineyard outside. An extensive study of inversion polymorphism in the two populations has been carried out. Furthermore, the relationship between inversion polymorphism and the viability of the second chromosome has been studied. The data regarding the total frequency of inversion-carrying chromosomes indicate a lower frequency in the cellar population than in the vineyard population. Some possibilities that could explain the behaviour of the chromosomes from the cellar in relation to the peculiar environment of this habitat are discussed. New endemic inversions…
Thermal Index for early non-invasive assessment of brain injury in newborns treated with therapeutic hypothermia: preliminary report.
2021
AbstractPerinatal asphyxia (PA) is the 3rd most common cause of neonatal death and one of the most common causes of severe neurological impairments in children. Current tools and measurements mainly based on the analysis of clinical evaluation and laboratory and electrophysiological tests do not give consistent data allowing to predict the severity of hypoxic-ischemic encephalopathy (HIE) until a magnetic resonance imaging (MRI) score is performed. The aim of this work is to evaluate the usefulness of the new index, called Thermal Index (TI) in the assessment of the degree of brain damage in newborns in the course of therapeutic hypothermia (TH) due to PA. This was a prospective, observatio…
Benign focal liver lesions: spectrum of findings on SonoVue-enhanced pulse-inversion ultrasonography.
2005
The prevalence of benign focal liver lesions (BFLL) is high both in the general population and in patients with known malignancies. The gray-scale ultrasound (US) technique is usually the first-line imaging modality used in the radiological workup of such lesions, but unfortunately it lacks specificity. Furthermore, Doppler examination may often be unsatisfactory owing to motion artefacts, or when small or deeply located lesions are evaluated. Recently, microbubble-based contrast agents used in combination with gray-scale US techniques, which are very sensitive to nonlinear behavior of microbubbles, have led to a better depiction of both microvasculature and macrovasculature of focal hepati…
Magnetresonanztomographie (MRT) der Leber und des Gehirns bei hämatologisch-onkologischen Patienten mit Fieber unbekannter Ursache
1998
PURPOSE To examine the advantage of liver and brain MRI in clinically anomalous haematological patients with fever of unknown origin. MATERIAL AND METHODS Twenty liver MRI (T2-TSE, T2-HASTE, T1-FLASH +/- Gd dynamic) and 16 brain MRI (T2-TSE, FLAIR, T1-TSE +/- Gd) were performed searching for a focus of fever with a suspected organ system. Comparison with clinical follow-up. RESULTS A focus was detected in 11/20 liver MRI. Candidiasis (n = 3), mycobacteriosis (n = 2), relapse of haematological disease (n = 3), graft versus host disease (n = 1), non-clarified (n02). The remaining 9 cases with normal MRI were not suspicious of infectious hepatic disease during follow-up. In brain MRI, 3/16 sho…
Asymmetric polysulfone and polyethersulfone membranes: effects of thermodynamic conditions during formation on their performance
2000
Abstract Membranes of polysulfone (PSU) and polyethersulfone (PES) were prepared from ternary and quaternary mixtures containing N , N -dimethylformamide (DMF) as solvent, water as non-solvent, and acetone (AC) as additive. The conditions for phase inversion and the desired phase separation mechanisms were selected on the basis of the phase behavior determined for the solvent/non-solvent/polymer systems. The influences of the composition of the casting solution, of the support, and of film thickness on structure and permeation properties of the membranes were analyzed by scanning electron microscopy (SEM) plus flux and separation experiments. The mechanisms of phase inversion that should pr…
Optimization of two-step techniques engineered for the preparation of polyamide 6 graphene oxide nanocomposites
2019
Abstract Different processing conditions to achieve polyamide 6 (PA6)-graphene oxide (GO) nanocomposites were investigated. GO was pre-dispersed in PA6 by three different solvent-based methods and, further, melt processed to prepare nanocomposites at two different loading levels, namely 2 and 5 wt.%. The evolution of rheological and mechanical properties was analyzed by investigating eventual changes in the microstructure and polymer crystallinity, aiming at providing a detailed processing-structure-properties relationship for these systems.
Study of inversion domain pyramids formed during the GaN:Mg growth
2003
AbstractThestudyofstructuraldefectsinducedbytheintroductionofMgduringthegrowthofMOCVDGaNispresented.Themagnesiumincorporationintothecrystalgrowthnotonlyinduceschangesinthestackingsequencefromhex-agonaltocubicstructures,butalsoinvertstheGaNpolarityfromGa-facetoN-face.Basedonthedifferentsurfacestructureandsurfacemigrationlengthofabsorbingprecursorsforeachpolaritytype(Ga-orN-face),the3DgrowthontopoftheN-facetriangulardefectisdescribed.TheN-facematerialischaracterizedbythreedanglingbondsofni-trogenthatpointuptowardthec-planesurface,enhancingthecrystalgrowthalongthec-axis. 2002ElsevierScienceLtd.Allrightsreserved. Keywords:Inversiondomain;Stackingfault;Polarity 1. IntroductionFurther progress tow…
Features of randomized electric-field assisted domain inversion in lithium tantalate
2011
We report on bulk and guided-wave second-harmonic generation via random Quasi-Phase-Matching in Lithium Tantalate. By acquiring the far-field profiles at several wavelengths, we extract statistical information on the distribution of the quadratic nonlinearity as well as its average period, both at the surface and in the bulk of the sample. By investigating the distribution in the two regions we demonstrate a non-invasive approach to the study of poling dynamics.
Advancements in Sustainable PVDF Copolymer Membrane Preparation Using Rhodiasolv® PolarClean As an Alternative Eco-Friendly Solvent
2021
In this work, Rhodiasolv® PolarClean was employed as a more sustainable solvent for the preparation of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) flat sheet membranes via phase inversion technique by coupling vapour induced phase separation (VIPS) and non-solvent induced phase separation (NIPS) processes. Preliminary calculations based on Hansen solubility parameters well predicted the solubilization of the polymer in the selected solvent. The effect of exposure time on humidity and the influence of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP) and sulfonated polyether sulfone (S-PES) on membrane properties and performance, were evaluated. Three different coagulation …
On the potential of 914 nm pumping of Nd:YVO4 for laser operation at 1064 nm
2011
1064 nm-Nd :YVO4 lasers were pumped at 808 nm and 914 nm. The comparative study shows that 914 nm-pumping is adapted for cw operation whereas 808 nm-pumping provides higher population inversion interesting for Q-switched operation.