Time dependent Ginzburg-Landau equation for an N-component model of self-assembled fluids

We study the time evolution of an N-component model of bicontinuous microemulsions based on a time dependent Ginzburg-Landau equation quenched from an high temperature uncorrelated state to the low temperature phases. The behavior of the dynamical structure factor $\tilde C(k,t)$ is obtained, in each phase, in the framework of the large-$N$ limit with both conserved (COP) and non conserved (NCOP) order parameter dynamics. At zero temperature the system shows multiscaling in the unstructured region up to the tricritical point for the COP whereas ordinary scaling is obeyed for NCOP. In the structured phase, instead, the conservation law is found to be irrelevant and the form $\tilde C(k,t) \sim t^{\alpha / z} f((|k-k_m| t^{1/z})$, with $\alpha=1$ and $z=2$, is obtained in every case. Simple scaling relations are also derived for the structure factor as a function of the final temperature of the thermal bath.Comment: 9 pages,Apste

Stability of quasi-entropy solutions of non-local scalar conservation laws

We prove the stability of entropy solutions of nonlinear conservation laws with respect to perturbations of the initial datum, the space-time dependent flux and the entropy inequalities. Such a general stability theorem is motivated by the study of problems in which the flux $P[u](t,x,u)$ depends possibly non-locally on the solution itself. For these problems we show the conditional existence and uniqueness of entropy solutions. Moreover, the relaxation of the entropy inequality allows to treat approximate solutions arising from various numerical schemes. This can be used to derive the rate of convergence of the recent particle method introduced in [Radici-Stra 2021] to solve a one-dimensional model of traffic with congestion, as well as recover already known rates for some other approximation methods

Diagnosis and treatment of pulmonary embolism: a multidisciplinary approach

The diagnosis of pulmonary embolism (PE) is frequently considered in patients presenting to the emergency department or when hospitalized. Although early treatment is highly effective, PE is underdiagnosed and, therefore, the disease remains a major health problem. Since symptoms and signs are non specific and the consequences of anticoagulant treatment are considerable, objective tests to either establish or refute the diagnosis have become a standard of care. Diagnostic strategy should be based on clinical evaluation of the probability of PE. The accuracy of diagnostic tests for PE are high when the results are concordant with the clinical assessment. Additional testing is necessary when the test results are inconsistent with clinical probability. The present review article represents the consensus-based recommendations of the Interdisciplinary Association for Research in Lung Disease (AIMAR) multidisciplinary Task Force for diagnosis and treatment of PE. The aim of this review is to provide clinicians a practical diagnostic and therapeutic management approach using evidence from the literature

Modeling the cosmological co-evolution of supermassive black holes and galaxies: II. The clustering of quasars and their dark environment

We use semi-analytic modeling on top of the Millennium simulation to study the joint formation of galaxies and their embedded supermassive black holes. Our goal is to test scenarios in which black hole accretion and quasar activity are triggered by galaxy mergers, and to constrain different models for the lightcurves associated with individual quasar events. In the present work we focus on studying the spatial distribution of simulated quasars. At all luminosities, we find that the simulated quasar two-point correlation function is fit well by a single power-law in the range 0.5 < r < 20 h^{-1} Mpc, but its normalization is a strong function of redshift. When we select only quasars with luminosities within the range typically accessible by today's quasar surveys, their clustering strength depends only weakly on luminosity, in agreement with observations. This holds independently of the assumed lightcurve model, since bright quasars are black holes accreting close to the Eddington limit, and are hosted by dark matter haloes with a narrow mass range of a few 10^12 h^{-1} M_sun. Therefore the clustering of bright quasars cannot be used to disentangle lightcurve models, but such a discrimination would become possible if the observational samples can be pushed to significantly fainter limits. Overall, our clustering results for the simulated quasar population agree rather well with observations, lending support to the conjecture that galaxy mergers could be the main physical process responsible for triggering black hole accretion and quasar activity.Comment: 17 pages, 16 figures, to be published on MNRA

Accidental discovery of a Tetraodontidae (<i>Sphoeroides marmoratus</i>) within a cuttlefish (<i>Sepia officinalis</i>) bought in a fish shop in Italy: risk assessment associated with the presence of Tetrodotoxin

The discovery of a pufferfish specimen (Tetraodontidae) inside a frozen cuttlefish, purchased by a fishmonger, and caught in the central-east Atlantic (FAO 34) is reported. The consumer, who reported this case to FishLab (Department of Veterinary Sciences, University of Pisa) for investigation, was a student of Veterinary Medicine at the University of Pisa. He recognized the Tetraodontidae because he attended practical lessons on fish morphological identification during the course of food inspection and was aware of the risks to human health linked to the Tetrodotoxin (TTX). In this study, the pufferfish was identified morphologically, using the FAO morphological keys, and molecularly, analyzing two markers, the cytochrome oxidase I (COI) and the cytochrome b genes, by DNA barcoding. The pufferfish was identified morphologically as Sphoeroides spp., and molecularly as Sphoeroides marmoratus using the COI gene (99-100% identity values). Literature reports that S. marmoratus from the eastern Atlantic contains high concentrations of TTX in the gonads and the digestive tract. However, the possible passage of TTX from fish to other organisms linked to contact or ingestion has never been reported. This represents the first case of a potentially toxic pufferfish entering the market inside another organism. The fact that a student observed this occurrence highlights the key role of citizen science in the management of emerging risks

Erbium emission in MOS light emitting devices: from energy transfer to direct impact excitation

The electroluminescence (EL) at 1.54 µm of metal-oxide-semiconductor (MOS) devices with Er3+ ions embedded in the silicon-rich silicon oxide (SRSO) layer has been investigated under different polarization conditions and compared with that of erbium doped SiO2 layers. EL time-resolved measurements allowed us to distinguish between two different excitation mechanisms responsible for the Er3+ emission under an alternate pulsed voltage signal (APV). Energy transfer from silicon nanoclusters (Si-ncs) to Er3+ is clearly observed at low-field APV excitation. We demonstrate that sequential electron and hole injection at the edges of the pulses creates excited states in Si-ncs which upon recombination transfer their energy to Er3+ ions. On the contrary, direct impact excitation of Er3+ by hot injected carriers starts at the Fowler-Nordheim injection threshold (above 5 MV cm−1) and dominates for high-field APV excitation

Coarsening and Pinning in the Self-consistent Solution of Polymer Blends Phase-Separation Kinetics

We study analytically a continuum model for phase-separation in binary polymer blends based on the Flory-Huggins-De Gennes free energy, by means of the self-consistent large-$n$ limit approach. The model is solved for values of the parameters corresponding to the weak and strong segregation limits. For deep quenches we identify a complex structure of intermediate regimes and crossovers characterized by the existence of a time domain such that phase separation is pinned, followed by a preasymptotic regime which in the scalar case corresponds to surface diffusion. The duration of the pinning is analytically computed and diverges in the strong segregation limit. Eventually a late stage dynamics sets in, described by scaling laws and exponents analogous to those of the corresponding small molecule systems.Comment: 16 pages, 5 figures. Submitted to Phys. Rev.

UNet and MobileNet CNN-based model observers for CT protocol optimization: comparative performance evaluation by means of phantom CT images

Purpose: The aim of this work is the development and characterization of a model observer (MO) based on convolutional neural networks (CNNs), trained to mimic human observers in image evaluation in terms of detection and localization of low-contrast objects in CT scans acquired on a reference phantom. The final goal is automatic image quality evaluation and CT protocol optimization to fulfill the ALARA principle. Approach: Preliminary work was carried out to collect localization confidence ratings of human observers for signal presence/absence from a dataset of 30,000 CT images acquired on a PolyMethyl MethAcrylate phantom containing inserts filled with iodinated contrast media at different concentrations. The collected data were used to generate the labels for the training of the artificial neural networks. We developed and compared two CNN architectures based respectively on Unet and MobileNetV2, specifically adapted to achieve the double tasks of classification and localization. The CNN evaluation was performed by computing the area under localization-ROC curve (LAUC) and accuracy metrics on the test dataset. Results: The mean of absolute percentage error between the LAUC of the human observer and MO was found to be below 5% for the most significative test data subsets. An elevated inter-rater agreement was achieved in terms of S-statistics and other common statistical indices. Conclusions: Very good agreement was measured between the human observer and MO, as well as between the performance of the two algorithms. Therefore, this work is highly supportive of the feasibility of employing CNN-MO combined with a specifically designed phantom for CT protocol optimization programs