Trust-Building through Social Media Communications in Disaster Management

open4Social media provides a digital space – a meeting place, for different people, often representing one or more groups in a society. The use of this space during a disaster, especially where information needs are high and the availability of factually accurate and ethically sourced data is scarce, has increased substantially over the last 5-10 years. This paper attempts to address communication in social media and trust between the public and figures of authority during a natural disaster in order to suggest communication strategies that can enhance or reinforce trust between these bodies before, during and after a natural disaster.openM. G. Busà; M. T. Musacchio; S. Finan; C. FennelBusa', MARIA GRAZIA; Musacchio, MARIA TERESA; S., Finan; C., Fenne

A knowledge-based approach to configuration layout, justification, and documentation

The design, development, and implementation is described of a prototype expert system which could aid designers and system engineers in the placement of racks aboard modules on Space Station Freedom. This type of problem is relevant to any program with multiple constraints and requirements demanding solutions which minimize usage of limited resources. This process is generally performed by a single, highly experienced engineer who integrates all the diverse mission requirements and limitations, and develops an overall technical solution which meets program and system requirements with minimal cost, weight, volume, power, etc. This system architect performs an intellectual integration process in which the underlying design rationale is often not fully documented. This is a situation which lends itself to an expert system solution for enhanced consistency, thoroughness, documentation, and change assessment capabilities

A Knowledge-Based Approach to Configuration Layout, Justification, and Documentation

The design, development, and implementation of a prototype expert system which could aid designers and system engineers in the placement of racks aboard modules on the Space Station Freedom are described. This type of problem is relevant to any program with multiple constraints and requirements demanding solutions which minimize usage of limited resources. This process is generally performed by a single, highly experienced engineer who integrates all the diverse mission requirements and limitations, and develops an overall technical solution which meets program and system requirements with minimal cost, weight, volume, power, etc. This system architect performs an intellectual integration process in which the underlying design rationale is often not fully documented. This is a situation which lends itself to an expert system solution for enhanced consistency, thoroughness, documentation, and change assessment capabilities

Single-particle spectral function for the classical one-component plasma

The spectral function for an electron one-component plasma is calculated self-consistently using the GW0 approximation for the single-particle self-energy. In this way, correlation effects which go beyond the mean-field description of the plasma are contained, i.e. the collisional damping of single-particle states, the dynamical screening of the interaction and the appearance of collective plasma modes. Secondly, a novel non-perturbative analytic solution for the on-shell GW0 self-energy as a function of momentum is presented. It reproduces the numerical data for the spectral function with a relative error of less than 10% in the regime where the Debye screening parameter is smaller than the inverse Bohr radius, kappa<1/a_B. In the limit of low density, the non-perturbative self-energy behaves as n^(1/4), whereas a perturbation expansion leads to the unphysical result of a density independent self-energy [W. Fennel and H. P. Wilfer, Ann. Phys. Lpz._32_, 265 (1974)]. The derived expression will greatly facilitate the calculation of observables in correlated plasmas (transport properties, equation of state) that need the spectral function as an input quantity. This is demonstrated for the shift of the chemical potential, which is computed from the analytical formulae and compared to the GW0-result. At a plasma temperature of 100 eV and densities below 10^21 cm^-3, both approaches deviate less than 10% from each other.Comment: 14 pages, 9 figures accepted for publication in Phys. Rev. E v2: added section V (application of presented formalism to chemical potential of the OCP

Phase- and intensity-resolved measurements of above threshold ionization by few-cycle pulses

We investigate the carrier-envelope phase (CEP) and intensity dependence of the longitudinal momentum distribution of photoelectrons resulting from above threshold ionization of argon by few-cycle laser pulses. The intensity of the pulses with a center wavelength of 750 nm is varied in a range between 0.7 × 1014 and . Our measurements reveal a prominent maximum in the CEP-dependent asymmetry at photoelectron energies of 2 U P (U P being the ponderomotive potential), that is persistent over the entire intensity range. Further local maxima are observed around 0.3 and 0.8 U P. The experimental results are in good agreement with theoretical results obtained by solving the three-dimensional time-dependent Schrödinger equation. We show that for few-cycle pulses, the amplitude of the CEP-dependent asymmetry provides a reliable measure for the peak intensity on target. Moreover, the measured asymmetry amplitude exhibits an intensity-dependent interference structure at low photoelectron energy, which could be used to benchmark model potentials for complex atoms

Evolution of dopant-induced helium nanoplasmas

Two-component nanoplasmas generated by strong-field ionization of doped helium nanodroplets are studied in a pump-probe experiment using few-cycle laser pulses in combination with molecular dynamics simulations. High yields of helium ions and a pronounced, droplet size-dependent resonance structure in the pump-probe transients reveal the evolution of the dopant-induced helium nanoplasma. The pump-probe dynamics is interpreted in terms of strong inner ionization by the pump pulse and resonant heating by the probe pulse which controls the final charge states detected via the frustration of electron-ion recombination

Phase- and intensity-resolved measurements of above threshold ionization by few-cycle pulses

We investigate the carrier-envelope phase and intensity dependence of the longitudinal momentum distribution of photoelectrons resulting from above-threshold ionization of argon by few-cycle laser pulses. The intensity of the pulses with a center wavelength of 750\,nm is varied in a range between $0.7 \times 10^{14}$ and \unit[5.5 \times 10^{14}]{W/cm^2}. Our measurements reveal a prominent maximum in the carrier-envelope phase-dependent asymmetry at photoelectron energies of 2\,$U_\mathrm{P}$ ($U_\mathrm{P}$ being the ponderomotive potential), that is persistent over the entire intensity range. Further local maxima are observed at 0.3 and 0.8\,$U_\mathrm{P}$. The experimental results are in good agreement with theoretical results obtained by solving the three-dimensional time-dependent Schr\"{o}dinger equation (3D TDSE). We show that for few-cycle pulses, the carrier-envelope phase-dependent asymmetry amplitude provides a reliable measure for the peak intensity on target. Moreover, the measured asymmetry amplitude exhibits an intensity-dependent interference structure at low photoelectron energy, which could be used to benchmark model potentials for complex atoms

Three-Dimensional Shapes of Spinning Helium Nanodroplets

A significant fraction of superfluid helium nanodroplets produced in a free-jet expansion have been observed to gain high angular momentum resulting in large centrifugal deformation. We measured single-shot diffraction patterns of individual rotating helium nanodroplets up to large scattering angles using intense extreme ultraviolet light pulses from the FERMI free-electron laser. Distinct asymmetric features in the wide-angle diffraction patterns enable the unique and systematic identification of the three-dimensional droplet shapes. The analysis of a large dataset allows us to follow the evolution from axisymmetric oblate to triaxial prolate and two-lobed droplets. We find that the shapes of spinning superfluid helium droplets exhibit the same stages as classical rotating droplets while the previously reported metastable, oblate shapes of quantum droplets are not observed. Our three-dimensional analysis represents a valuable landmark for clarifying the interrelation between morphology and superfluidity on the nanometer scale

Efficient Indirect Interatomic Coulombic Decay Induced by Photoelectron Impact Excitation in Large He Nanodroplets

Ionization of matter by energetic radiation generally causes complex secondary reactions which are hard to decipher. Using large helium nanodroplets irradiated by XUV photons, we show that the full chain of processes ensuing primary photoionization can be tracked in detail by means of high-resolution electron spectroscopy. We find that elastic and inelastic scattering of photoelectrons efficiently induces interatomic Coulombic decay (ICD) in the droplets. This type of indirect ICD even becomes the dominant process of electron emission in nearly the entire XUV range in large droplets with radius $\gtrsim40~$nm. Indirect ICD processes induced by electron scattering likely play an important role in other condensed phase systems exposed to ionizing radiation as well, including biological matter