Universal quantum magnetometry with spin states at equilibrium

We address metrological protocols for the estimation of the intensity and the orientation of a magnetic field, and show that quantum-enhanced precision may be achieved by probing the field with an arbitrary spin at thermal equilibrium. We derive a general expression for the ultimate achievable precision, as given by the quantum Fisher information, and express this quantity in terms of common thermodynamic quantities. We also seek for the optimal observable, and show that it corresponds to the spin projection along a suitable direction, defined by a universal function of the spin temperature. Finally, we prove the robustness of our scheme against deviations of the measured spin projection from optimality.Comment: Phys. Rev. Lett., in pres

Cochlear injury and adaptive plasticity of the auditory cortex

Growing evidence suggests that cochlear stressors as noise exposure and aging can induce homeostatic/maladaptive changes in the central auditory system from the brainstem to the cortex. Studies centered on such changes have revealed several mechanisms that operate in the context of sensory disruption after insult (noise trauma, drug-, or age-related injury). The oxidative stress is central to current theories of induced sensory-neural hearing loss and aging, and interventions to attenuate the hearing loss are based on antioxidant agent. The present review addresses the recent literature on the alterations in hair cells and spiral ganglion neurons due to noise-induced oxidative stress in the cochlea, as well on the impact of cochlear damage on the auditory cortex neurons. The emerging image emphasizes that noise-induced deafferentation and upward spread of cochlear damage is associated with the altered dendritic architecture of auditory pyramidal neurons. The cortical modifications may be reversed by treatment with antioxidants counteracting the cochlear redox imbalance. These findings open new therapeutic approaches to treat the functional consequences of the cortical reorganization following cochlear damage

Quantum-gate implementation in permanently coupled AF spin rings without need of local fields

We propose a scheme for the implementation of quantum gates which is based on the qubit encoding in antiferromagnetic molecular rings. We show that a proper engineering of the intercluster link would result in an effective coupling that vanishes as far as the system is kept in the computational space, while it is turned on by a selective excitation of specific auxiliary states. These are also shown to allow the performing of single- and two-qubit gates without an individual addressing of the rings by means of local magnetic fields.Comment: To appear in Physical Review Letter

Earthquake‐induced landslide scenarios for seismic microzonation. Application to the Accumoli area (Rieti, Italy)

Scenarios of earthquake-induced landslides are necessary for seismic microzonation (SM) studies since they must be integrated with the mapping of instability areas. The PARSIFAL (Probabilistic Approach to pRovide Scenarios of earthquake‐Induced slope FAiLures) approach provides extensive analyses, over tens to thousands of square kilometers, and is designed as a fully comprehensive methodology to output expected scenarios which depend on seismic input and saturation conditions. This allows to attribute a rating, in terms of severity level, to the landslide-prone slope areas in view of future engineering studies and designs. PARSIFAL takes into account first-time rock- and earth-slides as well as re-activations of existing landslides performing slope stability analyses of different failure mechanisms. The results consist of mapping earthquake-induced landslide scenarios in terms of exceedance probability of critical threshold values of co-seismic displacements (P[D≥Dc|a(t),ay]). PARSIFAL was applied in the framework of level 3 SM studies over the municipality area of Accumoli (Rieti, Italy), strongly struck by the 2016 seismic sequence of Central Apennines. The use of the PARSIFAL was tested for the first time to screen the Susceptibility Zones (ZSFR) from the Attention Zones (ZAFR) in the category of the unstable areas, according to the guidelines by Italian Civil Protection. The results obtained were in a GIS-based mapping representing the possibility for a landslide to be induced by an earthquake (with a return period of 475 years) in three different saturation scenarios (i.e. dry, average, full). Only 41% of the landslide-prone areas in the Municipality of Accumoli are existing events, while the remaining 59% is characterized by first-time earth- or rock-slides. In dry conditions, unstable conditions or P[D≥Dc|a(t),ay]>0 were for 54% of existing landslides, 17% of first-time rock-slides and 1% of first-time earth- slides. In full saturation conditions, the findings are much more severe since unstable conditions or P[D≥Dc|a(t),ay]>0 were found for 58% of the existing landslides and for more than 80% of first-time rock- and earth-slides. Moreover, comparison of the total area of the ZAFR versus ZSFR, resulted in PARSIFAL screening reducing of 22% of the mapped ZAFR

Geomorphology of the lower Mesopotamian plain at Tell Zurghul archaeological site

The landscape of the Lower Mesopotamia Plain (LMP) has been moulded by water-related processes, consequently, its Holocene geomorphic evolution has been strictly connected to the fluvial process and the anthropogenic water management since 8000 BC. About 6000 years ago, during the maximum marine ingression, the modern cities of Nasiriyah and Al-Amara were close to the Persian Gulf shoreline. Successively, the Tigris and Euphrates developed two wide delta systems, that prograded south-eastward developing a complex fluvial network. Remote sensing investigations over the LMP using satellite imagery and topographic analysis revealed the surficial expression of deltaic bodies with a lobate planform and several terminal distributary channels (TDCs), classifiable as tidal-influenced river-dominated deltas. Tell Zurghul archaeological site, belonging to the ancient State of Lagash, expanded in the western part of the recognized TDC during the Mid- and Late Holocene. Indeed, the occurrence of a divergent multi-channel system supplied water for the early civilizations, which improved the water management and prevented floods through a canals network. Therefore, the multi-sensor remote sensing approach over an area of 2850 km2 allowed us to recognize several fluvial landforms, both still active and relict, attributable to the Holocene riverscape of the LMP, as well as anthropogenic features and aeolian deposits. The Main map is a geomorphological map at the scale of 1:120,000 centred on Tell Zurghul, focusing on the geometry, spatial distribution, and state of activity of erosional and constructional landforms

DNS of a variable density jet in the supercritical thermodynamic state

Cryogenic rocket engines, advanced gas turbines and diesel engines are characterized by the injection of a liquid fuel into a high temperature and pressure chamber. Typically the fuel is injected at high enough pressure to be close or above the critical pressure. In these conditions the behavior of the fluid differs strongly from that of a perfect gas. It exhibits large variations of thermodynamic and transport properties also for small temperature changes, with significant effects on mixing and combustion processes. In this context an appropriate numerical simulation should take into account such thermodynamic phenomena via suitable equation of state and transport properties relations

Mitigation of Darrieus-Landau instability effects on turbulent premixed flames

Theoretical considerations on the competition between the most amplified modes for Darrieus-Landau (DL) hydrodynamic instability and turbulence timescales, show that, two extremal regimes can be identified: the instability-dominated and turbulence-dominated regimes. In the latter, also denoted as unified regime, both experiments and numerical simulations give evidence showing how the large scale, cusp-like structures of the flame front surface, typical of DL instability, are hindered by turbulent fluctuations. The result is that quantities such as turbulent flame propagation and front curvature statistics, which in the instability dominated regime are enhanced or modified by the overwhelming presence of hydrodynamic instability, are now mitigated and a unified regime is reached in which the characteristics of DL unstable and stable flame configurations become indistinguishable. In this work we analyze the concealing effects of increasing level of turbulence over the hydrodynamic Darrieus-Landau instability, and we show that, although some global indices such as the skewness of the curvature p.d.f. suggest that a unified regime is reached, others show the persistence of residual differences: in particular, the power spectral density of the flame front curvature. We use both experimental and numerical datasets of stable and unstable (based on linear stability analysis) flames, in conditions ranging from quasi laminar to significantly turbulent regimes

Curvature and velocity strain dependencies of burning speed in a turbulent premixed jet flame

In this work the dependency of the turbulent burning speed on flame stretch in a premixed jet flame is analyzed. Considering a reference system attached to the front, the flame stretch is split into three contributions based on flame front curvature, normal fluid velocity and divergence of tangential velocity. The turbulent burning velocity is derived from the measure of the divergence of the mean unconditioned velocity field, that is taken as an estimate of the mean reaction rate in the context of flamelet hypothesis. The results are in a reasonable agreement with the literature data on turbulent combustion rates. Though the present methodology is more complex than the usual one based on reactant consumption rate, it provides the local burning speed and not the overall one. Combining these measurements with the local flame stretch, we show that, for a given flame, it exists a wide region along the flame height where the increase of the local flame speed in respect to the laminar unstretched one (stretching factor) is constant. Since the Reynolds number controls the small-scale behavior of turbulence, these findings denote a direct connection between the local, turbulence-induced, flame front deformation and the increase of the local flame propagation speed. The aim of this work is to establish correlations between the three different terms of flame stretch and the turbulent combustion speed that can lead to the definition of suitable closure models for turbulent combustion numerical simulations