An automatic procedure to forecast tephra fallout

Tephra fallout constitutes a serious threat to communities around active volcanoes. Reliable short-term forecasts represent a valuable aid for scientists and civil authorities to mitigate the effects of fallout on the surrounding areas during an episode of crisis. We present a platform-independent automatic procedure with the aim to daily forecast transport and deposition of volcanic particles. The procedure builds on a series of programs and interfaces that automate the data flow and the execution and subsequent postprocess of fallout models. Firstly, the procedure downloads regional meteorological forecasts for the area and time interval of interest, filters and converts data from its native format, and runs the CALMET diagnostic model to obtain the wind field and other micro-meteorological variables on a finer local-scale 3-D grid defined by the user. Secondly, it assesses the distribution of mass along the eruptive column, commonly by means of the radial averaged buoyant plume equations depending on the prognostic wind field and on the conditions at the vent (granulometry, mass flow rate, etc). All these data serve as input for the fallout models. The initial version of the procedure includes only two Eulerian models, HAZMAP and FALL3D, the latter available as serial and parallel implementations. However, the procedure is designed to incorporate easily other models in a near future with minor modifications on the model source code. The last step is to postprocess the outcomes of models to obtain maps written in standard file formats. These maps contain plots of relevant quantities such as predicted ground load, expected deposit thickness and, for the case of or 3-D models, concentration on air or flight safety concentration thresholds

Characterization of partially accessible anisotropic spin chains in the presence of anti-symmetric exchange

We address quantum characterization of anisotropic spin chains in the presence of antisymmetric exchange, and investigate whether the Hamiltonian parameters of the chain may be estimated with precision approaching the ultimate limit imposed by quantum mechanics. At variance with previous approaches, we focus on the information that may be extracted by measuring only two neighbouring spins rather than a global observable on the entire chain. We evaluate the Fisher information (FI) of a two-spin magnetization measure, and the corresponding quantum Fisher information (QFI), for all the relevant parameters, i.e. the spin coupling, the anisotropy, and the Dzyaloshinskii Moriya (DM) parameter. Our results show that the reduced system made of two neighbouring spins may be indeed exploited as a probe to characterize global properties of the entire system. In particular, we find that the ratio between the FI and the QFI is close to unit for a large range of the coupling values. The DM coupling is beneficial for coupling estimation, since it leads to the presence of additional bumps and peaks in the FI and QFI, which are not present in a model that neglects exchange interaction and may be exploited to increase the robustness of the overall estimation procedure. Finally, we address the multiparameter estimation problem, and show that the model is compatible but sloppy, i.e. both the Uhlmann curvature and the determinant of the QFI matrix vanish. Physically, this means that the state of the system actually depends only on a reduced numbers of combinations of parameters, and not on all of them separately.Comment: 10 pages, 7 figure

Characterization of partially accessible anisotropic spin chains in the presence of anti-symmetric exchange

We address quantum characterization of anisotropic spin chains in the presence of anti-symmetric exchange, and investigate whether the Hamiltonian parameters of the chain may be estimated with precision approaching the ultimate limit imposed by quantum mechanics. At variance with previous approaches, we focus on the information that may be extracted by measuring only two neighboring spins rather than a global observable on the entire chain. We evaluate the Fisher information (FI) of a two-spin magnetization measure, and the corresponding quantum Fisher information (QFI), for all the relevant parameters, i.e. the spin coupling, the anisotropy, and the Dzyaloshinskii–Moriya (DM) parameter. Our results show that the reduced system made of two neighboring spins may be indeed exploited as a probe to characterize global properties of the entire system. In particular, we find that the ratio between the FI and the QFI is close to unit for a large range of the coupling values. The DM coupling is beneficial for coupling estimation, since it leads to the presence of additional bumps and peaks in the FI and QFI, which are not present in a model that neglects exchange interaction and may be exploited to increase the robustness of the overall estimation procedure. Finally, we address the multiparameter estimation problem, and show that the model is compatible but sloppy, i.e. both the Uhlmann curvature and the determinant of the QFI matrix vanish. Physically, this means that the state of the system actually depends only on a reduced numbers of combinations of parameters, and not on all of them separately

Il progetto EPLORIS: La ricostruzione virtuale dell'eruzione del Vesuvio

The main objective of the Exploris project consists in the quantitative analysis of explosive eruption risk in densely populated EU volcanic regions and the evaluation of the likely effectiveness of possible mitigation measures through the development of volcanic risk facilities (such as supercomputer models, vulnerability databases, and probabilistic risk assessment protocols) and their application to high-risk European volcanoes. Exploris’ main ambition is to make a significant step forward in the assessment of explosive eruption risk in highly populated EU cities and islands. For this project, a new simulation model, based on fundamental transport laws to describe the 4D (3D spatial co-ordinates plus time) multiphase flow dynamics of explosive eruptions has been developed and parallelized in INGV and CINECA. Moreover, CINECA developed specific tools to efficiently visualise the results of simulations. This article presents the results of the large numerical simulations, carred out with CINECA’s Supercomputers, to describe the collapse of the volcanic eruption column and the propagation of pyroclastic density currents, for selected medium scale (sub-Plinian) eruptive scenarios at Vesuvius

Human (in)security and psychological well-being in Palestinian children living amidst military violence: A qualitative participatory research using interactive maps

Background Research has widely evidenced the effects of war and political violence on the functioning of children, with a great accord in diagnosing children\u27s psychological burdens related to their exposure to violence. Yet, within this literature, the influence of the chronic sense of insecurity on their psychological functioning during and after hostilities remains unexplored. Methods The present study aimed at exploring interrelated relationships between the perceived insecurity and the children\u27s psychological well-being and their adjustment to trauma. Based on drawings and walk-along interviews with 75 Palestinian children, residents of both the West Bank and Gaza Strip, we offer an analysis of human security-related risks and protective factors that contribute to either promoting or undermining the child\u27s psychological functioning in a context characterized by chronic instability and political violence. Results A complex network of sources of security and insecurity emerged from the narratives depicting an ecological portrait encompassing the determinants of children\u27s mental health and psychological functioning. The TCA led to the identification of eight main themes: school and associativism; social relations and house as a source of security/insecurity; military occupation as a source of insecurity; national and political identity as a source of safety; mosque and spirituality as a source of safety/unsafety; environment as a source of security/insecurity; and mental health. Discussion An approach encompassing human security as an explicative model can help in exhaustively portraying the complexity of the Palestinian children\u27s suffering and their competence in adjusting to their traumatic reality. The study draws attention to social, political, environmental and economic determinants of children psychological well-being

An application of parallel computing to the simulation of volcanic eruptions

A parallel code for the simulation of the transient 3D dispersal of volcanic particles produced by explosive eruptions is presented. The model transport equations, based on the multiphase flow theory, describe the atmospheric dynamics of the gas-particle mixture ejected through the volcanic crater. The numerics is based on a finite-volume discretization scheme and a pressure-based iterative non-linear solver suited to compressible multiphase flows. The code has been parallelized by adopting an ad hoc domain partitioning scheme that enforces the load balancing. An optimized communication layer has been built over the Message-Passing Interface. The code proved to be remarkably efficient on several high-performance platforms and makes it possible to simulate fully 3D eruptive scenarios on realistic volcano topography

investigation of particle dynamics and classification mechanism in a spiral jet mill through computational fluid dynamics and discrete element methods

Abstract Predicting the outcome of jet-milling based on the knowledge of process parameters and starting material properties is a task still far from being accomplished. Given the technical difficulties in measuring thermodynamics, flow properties and particle statistics directly in the mills, modelling and simulations constitute alternative tools to gain insight in the process physics and many papers have been recently published on the subject. An ideal predictive simulation tool should combine the correct description of non-isothermal, compressible, high Mach number fluid flow, the correct particle-fluid and particle-particle interactions and the correct fracture mechanics of particle upon collisions but it is not currently available. In this paper we present our coupled CFD-DEM simulation results; while comparing them with the recent modelling and experimental works we will review the current understating of the jet-mill physics and particle classification. Subsequently we analyze the missing elements and the bottlenecks currently limiting the simulation technique as well as the possible ways to circumvent them towards a quantitative, predictive simulation of jet-milling

Coin dimensionality as a resource in quantum metrology involving discrete-time quantum walks

We address metrological problems where the parameter of interest is encoded in the internal degree of freedom of a discrete-time quantum walker, and provide evidence that coin dimensionality is a potential resource to enhance precision. In particular, we consider estimation problems where the coin parameter governs rotations around a given axis and show that the corresponding quantum Fisher information (QFI) may increase with the dimension of the coin. We determine the optimal initial state of the walker to maximize the QFI and discuss whether, and to which extent, precision enhancement may be achieved by measuring only the position of the walker. Finally, we consider Grover-like encoding of the parameter and compare results with those obtained from rotation encoding.Comment: revised version, 14 pages, 5 figure

Continuous-time quantum walks in the presence of a quadratic perturbation

We address the properties of continuous-time quantum walks with Hamiltonians of the form H = L + \u3bbL2, with L the Laplacian matrix of the underlying graph and the perturbation \u3bbL2 motivated by its potential use to introduce next-nearest-neighbor hopping. We consider cycle, complete, and star graphs as paradigmatic models with low and high connectivity and/or symmetry. First, we investigate the dynamics of an initially localized walker. Then we devote attention to estimating the perturbation parameter \u3bb using only a snapshot of the walker dynamics. Our analysis shows that a walker on a cycle graph spreads ballistically independently of the perturbation, whereas on complete and star graphs one observes perturbation-dependent revivals and strong localization phenomena. Concerning the estimation of the perturbation, we determine the walker preparations and the simple graphs that maximize the quantum Fisher information. We also assess the performance of position measurement, which turns out to be optimal, or nearly optimal, in several situations of interest. Besides fundamental interest, our study may find applications in designing enhanced algorithms on graphs

Speed and power predictors of change of direction ability in elite snow athletes

Change of direction ability (COD speed) is an important physical component of snow sports. The aim of this study was to investigate the relationships between regular speed and vertical jumping ability, and COD speed in elite snow athletes. Moreover, the correlations between relative mean propulsive power (assessed in the jump squat exercise) and COD speed were quantified. Sixteen elite snow sport athletes executed squat jumps, countermovement jumps, jump squats, and 25 m sprint tests, in addition to a Zig-zag change of direction speed test. The outcomes revealed that vertical jumping height and mean propulsive power are strongly correlated (r ≈ 0.90) with COD speed. Furthermore, snow athletes capable of sprinting faster in a linear course of 25 m performed better in COD speed tests ( r = 0.91). Our results support the use of loaded and unloaded vertical jumping and regular speed tests to evaluate/monitor predictors of COD speed in elite snow athletes. Finally, these relationships suggest that plyometrics and regular speed training should be considered by coaches as effective strategies to enhance COD ability in this specific group of subjects