Quantum-Gravitational Effects on Primordial Power Spectra in Slow-Roll Inflationary Models

We review the computation of the power spectra of inflationary gauge-invariant perturbations in the context of canonical quantum gravity for generic slow-roll models. A semiclassical approximation, based on an expansion in inverse powers of the Planck mass, is applied to the complete Wheeler-DeWitt equation describing a perturbed inflationary universe. This expansion leads to a hierarchy of equations at consecutive orders of the approximation and allows us to write down a corrected Schrodinger equation that encodes information about quantum-gravitational effects. The analytical dependence of the correction to the power spectrum on the wavenumber is obtained. Nonetheless, some numerical work is needed in order to obtain its precise value. Finally, it is shown that the correction turns out to be positive, which leads to an enhancement of the power spectrum especially prominent for large scales. We will also discuss whether this correction leads to a measurable effect in the cosmic microwave background anisotropies.We thank Claus Kiefer for collaboration on the subject under discussion in this proceedings contribution. D. B. is supported by project FIS2014-57956-P of the Spanish Ministry of Economy and Competitiveness and by project IT956-16 of the Basque Government. The research of M. K. was financed by the Polish National Science Center Grant DEC-2012/06/A/ST2/00395

Successful implementation of discrete event simulation: the case of an Italian emergency department

This paper focuses on the study of a practical management problem faced by a healthcare {\it emergency department} (ED) located in the north of Italy. The objective of our study was to propose organisational changes in the selected ED, which admits approximately 7000 patients per month, aiming at improving key performance indicators related to patient satisfaction, such as the waiting time. Our study is based on a design thinking process that adopts a {\it discrete event simulation} (DES) model as the main tool for proposing changes. We used the DES model to propose and evaluate the impact of different improving scenarios. The model is based on historical data, on the observation of the current ED situation, and information obtained from the ED staff. The results obtained by the DES model have been compared with those related to the existing ED setting, and then validated by the ED managers. Based on the results we obtained, one of the tested scenarios was selected by the ED for implementation.Comment: 24 pages, 8 figures and 4 table

Post-fire Practices Benefits on Vegetation Recovery and Soil Conservation in a Mediterranean Area

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG.[Abstract] Post-fire practices (PFP) aim to reduce soil erosion and favour vegetation recovery, but their effectiveness is spatially heterogeneous and under debate because of the economic and environmental costs. This study evaluates the different changes (Δ) of canopy cover (CC), sediment connectivity (SC) and local topography in four areas affected by the Pinet fire in eastern Spain (August 8th, 2018) and managed with: totally burnt with tree removal and long log erosion barriers (LEBs) (Pinet-1), partially burnt without PFP (Pinet-2), totally burnt with tree removal and short LEBs (Pinet-3), and totally burnt without PFP (Pinet-4). An unburnt nearby area was used as control site (Pinet-5). High-resolution images obtained before the fire and during two drone flights after the fire (10.5 and 5.5 months after the fire and PFP; and 18 and 13 months after the fire and PFP) were analysed; and LiDAR- and SfM-derived digital elevation models used to compute the Aggregated Index of SC (AICv2). After correcting calculations, because of the different input sources, and excluding the forest roads (=3.6% of the total surface), CC in the first post-fire scenario was of 25.5% (−40.4% with respect to the pre-fire scenario), 14.5% (−68.4%), 23.8% (−43.7%), 26.9% (−26.5%) and 29.6% (−32.7%) in Pinet-1, P-2_totally_burnt, P-2_partially_burnt, P-3 and P-4; and ΔCC among the drone flights were of +2.45%, +0.02% and +10.54% in Pinet-1, Pinet-3 and Pinet-4. The annual CC recovery rate decrease from 27.5% to 19.1% per year between the first and the second post-fire scenario, indicating a quick vegetation recovery, especially in the first year, and considering the surface area covered by rocks (=16.3%). Topographic changes indicated that not install LEBs favoured shorter flow length pathways after the fire, and thus, runoff will flow faster to cover the same area, achieving higher velocity and thus soil detachment capacity. Sediment connectivity increased in all burnt sub-sites after the fire (=+32.4%), but the increments in the two sub-sites with LEBs were 36% lower than the increase in the sub-sites without LEBs. The increase of connectivity in the first and second post-fire scenarios was −32% and −45% in the sub-site with long LEBs compared with the sub-site with short LEBs. Overall, LEBs effectively favoured vegetation recovery, lengthened overland flow pathways, and reduced sediment transport in the early months, but their usefulness was not as pronounced during the second post-fire year, although these results may be influenced by the Mediterranean conditions of the site.This research was funded by the project SPECTORS, which is a Dutch-German cooperation project funded by INTERREG V-A Deutschland-Nederland. This research was also included in the research activities of the European COST Action FIRElinks (CA18135) “Fire in the Earth System: Science & Society” (European Union Framework Programme Horizon 2020). This research was also partially funded by the Netherlands Ministry of Agriculture, Nature and Food Quality (grant number KB-36–005-006/008; Nature-inclusive Transitions)Netherlands Ministry of Agriculture, Nature and Food Quality; KB-36–005-006/00

Enhanced arc-flow formulations to minimize weighted completion time on identical parallel machines

We consider the problem of scheduling a set of jobs on a set of identical parallel machines, with the aim of minimizing the total weighted completion time. The problem has been solved in the literature with a number of mathematical formulations, some of which require the implementation of tailored branch-and-price methods. In our work, we solve the problem instead by means of new arc-flow formulations, by first representing it on a capacitated network and then invoking a mixed integer linear model with a pseudo-polynomial number of variables and constraints. According to our computational tests, existing formulations from the literature can solve to proven optimality benchmark instances with up to 100 jobs, whereas our most performing arc-flow formulation solves all instances with up to 400 jobs and provides very low gap for larger instances with up to 1000 jobs

On the prospects of imaging Sagittarius A* from space

Very Long Baseline Interferometry (VLBI) at sub-millimeter waves has the potential to image the shadow of the black hole in the Galactic Center, Sagittarius A* (Sgr A*), and thereby test basic predictions of the theory of general relativity. We investigate the imaging prospects of a new Space VLBI mission concept. The setup consists of two satellites in polar or equatorial circular Medium-Earth Orbits with slightly different radii, resulting in a dense spiral-shaped uv-coverage with long baselines, allowing for extremely high-resolution and high-fidelity imaging of radio sources. We simulate observations of a general relativistic magnetohydrodynamics model of Sgr A* for this configuration with noise calculated from model system parameters. After gridding the $uv$-plane and averaging visibilities accumulated over multiple months of integration, images of Sgr A* with a resolution of up to 4 $\mu$as could be reconstructed, allowing for stronger tests of general relativity and accretion models than with ground-based VLBI.Comment: 4 pages, 4 figures, published in Proceedings IAU Symposium No. 342, 201

Drones InSecurity

This project is about testing the security of casual/commercial drones. For this, we tested drones from the company Parrot, but the conclusions apply to all drones based on WiFi controllers. To test drones security, the project was divided in two parts. The first part is stream sniffing. This means capturing the video stream that a drone transmits to its connected user and afterwards reconstructing it, to see the actual video footage. The second part of the project is the hi- jacking of drones. This includes the complete capturing of a targeted drone, with access to all the controls and its video stream. After the capturing, the victim should fly autonomously, following our drone to a location we decide

Measurements and modeling of Alfven eigenmode induced fast ion transport and loss in DIII-D and ASDEX Upgrade

Neutral beam injection into reversed magnetic shear DIII-D and ASDEX Upgrade plasmas produces a variety of Alfve´nic activity including toroidicity-induced Alfve´n eigenmodes and reversed shear Alfve´n eigenmodes (RSAEs). These modes are studied during the discharge current ramp phase when incomplete current penetration results in a high central safety factor and increased drive due to multiple higher order resonances. Scans of injected 80 keV neutral beam power on DIII-D showed a transition from classical to AE dominated fast ion transport and, as previously found, discharges with strong AE activity exhibit a deficit in neutron emission relative to classical predictions. By keeping beam power constant and delaying injection during the current ramp, AE activity was reduced or eliminated and a significant improvement in fast ion confinement observed. Similarly, experiments in ASDEX Upgrade using early 60 keV neutral beam injection drove multiple unstable RSAEs. Periods of strong RSAE activity are accompanied by a large (peak dSn=Sn 60%) neutron deficit. Losses of beam ions modulated at AE frequencies were observed using large bandwidth energy and pitch resolving fast ion loss scintillator detectors and clearly identify their role in the process. Modeling of DIII-D loss measurements using guiding center following codes to track particles in the presence of ideal magnetohydrodynamic (MHD) calculated AE structures (validated by comparison to experiment) is able to reproduce the dominant energy, pitch, and temporal evolution of these losses. While loss of both co and counter current fast ions occurs, simulations show that the dominant loss mechanism observed is the mode induced transition of counter-passing fast ions to lost trapped orbits. Modeling also reproduces a coherent signature of AE induced losses and it was found that these coherent losses scale proportionally with the amplitude; an additional incoherent contribution scales quadratically with the mode amplitude. VC 2011 American Institute of Physics.US Department of Energy DE-FC02-04ER54698, SC-G903402, DE-AC02-99CH11466, DE-FG03-97ER54415, DE-FG02-89ER53296, DE-FG02-08ER5499

Beam ion losses due to energetic particle geodesic acoustic modes

We report the first experimental observations of fast-ion loss in a tokamak due to energetic particle driven geodesic acoustic modes (EGAMs). A fast-ion loss detector installed on the DIII-D tokamak observes bursts of beam ion losses coherent with the EGAM frequency. The EGAM activity results in a significant loss of beam ions, comparable to the first orbit losses. The pitch angles and energies of the measured fast-ion losses agree with predictions from a full orbit simulation code SPIRAL, which includes scattering and slowing-down.U.S. Department of Energy DE-FC02-04ER 54698, SC-G903402, DE-AC02-09CH1146