Enhancing the significance of gravitational wave bursts through signal classification

The quest to observe gravitational waves challenges our ability to discriminate signals from detector noise. This issue is especially relevant for transient gravitational waves searches with a robust eyes wide open approach, the so called all- sky burst searches. Here we show how signal classification methods inspired by broad astrophysical characteristics can be implemented in all-sky burst searches preserving their generality. In our case study, we apply a multivariate analyses based on artificial neural networks to classify waves emitted in compact binary coalescences. We enhance by orders of magnitude the significance of signals belonging to this broad astrophysical class against the noise background. Alternatively, at a given level of mis-classification of noise events, we can detect about 1/4 more of the total signal population. We also show that a more general strategy of signal classification can actually be performed, by testing the ability of artificial neural networks in discriminating different signal classes. The possible impact on future observations by the LIGO-Virgo network of detectors is discussed by analysing recoloured noise from previous LIGO-Virgo data with coherent WaveBurst, one of the flagship pipelines dedicated to all-sky searches for transient gravitational waves

The Floodplain Woods of Tuscany

The contraction of lowland forests throughout Europe began in remote times and then intensified strongly with land reclamation by agriculture and urbanization during the first half of the last century. We present a map of the Floodplain Woods of Tuscany on a scale of 1:300,000 as a synthesis of that built at the scale of 1:10,000 and the methods used to obtain it. Nearly 90% of the patches contain habitats of concern to conservation, according to the Habitat Directive. The Tuscan Floodplain Woods remained prevalent in coastal areas, where some levels of protection are guaranteed by the presence of several protected areas, whereas they have practically vanished in the other parts of the regional territory. The resulting patches are very small and distant from each other, so only in-depth management of all potential floodplain forest areas, taking into consideration patches for their regeneration, can be useful to assure their conservation

Guest or pest? Spatio-temporal occurrence and effects on soil and vegetation of the wild boar on the Elba island

In areas where allochthonous large mammals, such as the wild boars (Sus scrofa), occur in high density, human-wildlife conflicts may arise. In these contexts, assessing spatio-temporal patterns of the introduced population is paramount to its management. Here, we studied wild boars in the Elba island, Italy, where they have been introduced and are perceived as pests. While crop-raiding has been documented, no studies addressed the spatio-temporal occurrence, nor the impact of foraging on natural habitat. We surveyed the Western part of the island with three camera trapping surveys within one year. We found that the species' estimated occupancy probability was higher in summer-autumn (0.75±0.14) and winter-early spring (0.70±0.10) than in late spring-summer (0.53±0.15), whereas detection probability did not vary. Occupancy was significantly associated with elevation and vegetation cover, with preference for lower elevation and woodland. The lower site use of wild boars during spring-summer might reflect lower food availability in this season, and/or movements towards landfarms outside the sampled area. Detectability increased with proximity to roads during spring-summer and decreased with humans' relative abundance in the other periods. Moreover, boars were mainly nocturnal, with an overlap with human activity that decreased when human presence was higher. Combined, these suggest behavioural avoidance of human disturbance by boars. We also evaluated the impact of boars' foraging on the soil and vegetation and found that it was higher in pine plantations than other covers, however, it was not associated with variation in boars' occupancy across habitats. Our results indicate that the spatio-temporal activity of wild boars on Elba island appears driven by seasonal preferences for food-rich cover and avoidance of human disturbance. The lowered site use in months with lower resources could partially reflect increased proximity to settled and farmed areas, which may, in turn, trigger crop-raiding and hence the negative perception by residents

A consensus panel review of central nervous system effects of the exposure to low-intensity extremely low-frequency magnetic fields

BACKGROUND: A large number of studies explored the biological effects of extremely low-frequency (0-300 Hz) magnetic fields (ELF-MFs) on nervous system both at cellular and at system level in the intact human brain reporting several functional changes. However, the results of different studies are quite variable and the mechanisms of action of ELF-MFs are still poorly defined. The aim of this paper is to provide a comprehensive review of the effects of ELF-MFs on nervous system. METHODS: We convened a workgroup of researchers in the field to review and discuss the available data about the nervous system effects produced by the exposure to ELF-MFs. MAIN FINDINGS/DISCUSSION: We reviewed several methodological, experimental and clinical studies and discussed the findings in five sections. The first section analyses the devices used for ELF-MF exposure. The second section reviews the contribution of the computational methods and models for investigating the interaction between ELF-MFs and neuronal systems. The third section analyses the experimental data at cellular and tissue level showing the effects on cell membrane receptors and intracellular signaling and their correlation with neural stem cell proliferation and differentiation. The fourth section reviews the studies performed in the intact human brain evaluating the changes produced by ELF-MFs using neurophysiological and neuropsychological methods. The last section shows the limits and shortcomings of the available data, evidences the key challenges in the field and tracks directions for future research

First principles fluid modelling of magnetic island stabilization by ECCD

International audienceTearing modes are MHD instabilities that reduce the performances of fusion devices. They can however be controlled and suppressed using Electron Cyclotron Current Drive (ECCD) as demonstrated in various tokamaks. In this work, simulations of islands stabilization by ECCD-driven current have been carried out using the toroidal nonlinear 3D full MHD code XTOR-2F, in which a current-source term modeling the ECCD has been implemented. The efficiency parameter is computed and its variations with respect to source width and location are computed. The influence of parameters such as current intensity, source width and position with respect to the island is evaluated and compared to the Modified Rutherford Equation. We retrieve a good agreement between the simulations and the analytical predictions concerning the variations of control efficiency with source width and position. We also show that the 3D nature of the current source term can lead to the onset of an island if the source term is precisely applied on a rational surface. We report the observation of a flip phenomenon in which the O-and X-Points of the island rapidly switch their position in order for the island to take advantage of the current drive to grow

Fatigue in multiple sclerosis: The role of thalamus

Fatigue is very common in multiple sclerosis (MS) and is often considered as its most disabling symptom. Over the last 20 years, an increasing number of studies have evaluated the pathogenetic bases of MS-related fatigue. Converging evidence from neurophysiology and neuroimaging research suggests that a dysfunction in a cortico-subcortical pathway, centered on thalamus, is involved in the pathogenesis of fatigue. However, type and significance of such dysfunction remain unknown, and some studies reported an increase in the activity and connectivity within the thalamic network, whereas others suggested its reduction. Hereby, we review the results of neuroimaging studies supporting the different hypotheses about the role of thalamic network in the pathophysiology of MS-related fatigue and discuss limitations and shortcomings of available data, highlighting the key challenges in the field and the directions for future research

Reconstruction of the gravitational wave signal h(t)h(t) during the Virgo science runs and independent validation with a photon calibrator

The Virgo detector is a kilometer-scale interferometer for gravitational wave detection located near Pisa (Italy). About 13 months of data were accumulated during four science runs (VSR1, VSR2, VSR3 and VSR4) between May 2007 and September 2011, with increasing sensitivity. In this paper, the method used to reconstruct, in the range 10 Hz-10 kHz, the gravitational wave strain time series $h(t)$ from the detector signals is described. The standard consistency checks of the reconstruction are discussed and used to estimate the systematic uncertainties of the $h(t)$ signal as a function of frequency. Finally, an independent setup, the photon calibrator, is described and used to validate the reconstructed $h(t)$ signal and the associated uncertainties. The uncertainties of the $h(t)$ time series are estimated to be 8% in amplitude. The uncertainty of the phase of $h(t)$ is 50 mrad at 10 Hz with a frequency dependence following a delay of 8 $\mu$s at high frequency. A bias lower than $4\,\mathrm{\mu s}$ and depending on the sky direction of the GW is also present.Comment: 35 pages, 16 figures. Accepted by CQ