From Solar and Stellar Flares to Coronal Heating: Theory and Observations of How Magnetic Reconnection Regulates Coronal Conditions

There is currently no explanation of why the corona has the temperature and density it has. We present a model which explains how the dynamics of magnetic reconnection regulates the conditions in the corona. A bifurcation in magnetic reconnection at a critical state enforces an upper bound on the coronal temperature for a given density. We present observational evidence from 107 flares in 37 sun-like stars that stellar coronae are near this critical state. The model may be important to self-organized criticality models of the solar corona.Comment: 13 pages, 2 figures, accepted to Ap. J. Lett., February 200

Quantum quench in a harmonically trapped one-dimensional Bose gas

We study the nonequilibrium dynamics of a one-dimensional Bose gas trapped by a harmonic potential for a quench from zero to infinite interaction. The different thermodynamic limits required for the equilibrium pre- and post-quench Hamiltonians are the origin of a few unexpected phenomena that have no counterparts in the translational-invariant setting. We find that the dynamics is perfectly periodic with breathing time related to the strength of the trapping potential. For very short times, we observe a sudden expansion leading to an extreme dilution of the gas and to the emergence of slowly decaying tails in the density profile. The haste of the expansion induces an undertow-like effect with a pronounced local minimum of the density at the center of the trap. At half period there is a refocusing phenomenon characterized by a sharp central peak of the density, juxtaposed to algebraically decaying tails. We finally show that the time-averaged density is correctly captured by a generalized Gibbs ensemble built with the conserved mode occupations

Full counting statistics in the spin-1/2 Heisenberg XXZ chain

The spin-1/2 Heisenberg chain exhibits a quantum critical regime characterized by quasi long-range magnetic order at zero temperature. We quantify the strength of quantum fluctuations in the ground state by determining the probability distributions of the components of the (staggered) subsystem magnetization. Some of these exhibit scaling and the corresponding universal scaling functions can be determined by free fermion methods and by exploiting a relation with the boundary sine-Gordon model

Measuring magnitude and rate of vertical movements in the offshore Capo Vaticano (W Calabria) using lowstand coastal prisms and wavebuilt terraces

The magnitude and rate of vertical movements have been measured in the offshore Capo Vaticano (western Calabria) for the Late Pleistocene - Holocene on the basis of the depth of submerged coastal prism and associated wave-built terrace formed during the sea-level lowstand of the Last Glacial Maximum (LGM). Uplifted and submerged terraces have proved to be valuable recorders of vertical motion in many locations around the world (e.g. DICKINSON, 2001; WEBSTER et alii, 2004) as the depth of their tops appear to be controlled by the sea-level. In the eastern Tyrrhenian margins, depending on the hydraulic energy conditions (i.e. waves and wind-induced currents), the average water depth of terraced surface of lowstand coastal prisms was probably 15-20 m (CHIOCCI & ORLANDO, 1996). A series of LGM lowstand coastal prisms and associated wave-built terraces were identified on a new set of very highresolution reflection seismic profiles acquired along the continental shelf and upper slope of the western Calabria continental margin. Data processing included time-depth conversion and the interpretation of the resulting seismic lines was performed using a GIS-based software package. Seismic interpretation highlight that along the offshore Capo Vaticano the slope-breaks associated with wave-built terraced formed during the LGM deepens from ~130 m (cluster A) to ~170 m (cluster B) below sea level (bsl) as one moves from southwest to the northeast, over a distance of ~21 km (Fig. 1). Farther to the north, along the western flank of the Calabrian Arc, an average depth for the slope-breaks of ~165 m is measured. Removal of the non tectonic component of vertical changes using an ice-volume equivalent eustatic sea-level compilation (LAMBECK et alii, 2011) indicates ~15 (± 5) m of uplift and ~25 (± 5) m of subsidence during the post-LGM for the southern and northern sectors offshore Capo Vaticano, respectively. The resulting average uplift and subsidence rates (both regional and local components) for the last 20 (± 2) k.y. are 0.75 (±0.325) mm/y and 1.25 (±0.375) mm/y, respectively. The integration of the new data with those available in the literature (e.g. TORTORICI et alii, 2003; CUCCI & TERTULLIANI, 2010; FERRANTI et alii, 2011) may provide information on fault kinematics and constraints on slip rates of tectonic structures that are relevant for earthquake hazard analysis of western Calabrian margin. REFERENCES CHIOCCI, F. L. & ORLANDO L. (1996) - Lowstand terraces on Tyrrhenian Sea steep continental scope. Marine Geology, 134, 127-143. CUCCI, L. & TERTULLIANI A. (2010) - The Capo Vaticano (Calabria) coastal terraces and the 1905 M7 earthquake: the geomorphological signature of regional uplift and coseismic slip in southern Italy. Terra Nova, 22, 378–389. doi: 10.1111/j.1365-3121.2010.00961.x DICKINSON, W.R. (2001)- Paleoshoreline record of relative Holocene sea levels on Pacific islands. Earth-Science Reviews, 55, p. 191–234. doi: 10.1016/S0012-8252 (01)00063-0. FERRANTI L., SCICCHITANO G., SPAMPINATO C. R., ANTONIOLI F., MONACO C. (2011) - Holocene coastal uplift at Capo Vaticano, Calabria: implications for differential deformation rates. Riassunti VIII Forum FIST Geoitalia 2011, 19-23 Settembre 2011, Torino. Epitome, 4, 153. LAMBECK, K., F. ANTONIOLI, M. ANZIDEI, L. FERRANTI, G. LEONI, G. SCICCHITANO & S. SILENZI (2011) - Sea level change along the Italian coast during the Holocene and projections for the future. Quaternary International, 232, 250-257. WEBSTER, J.M., WALLACE, L., SILVER, E., APPLEGATE, B., POTTS, D., BRAGA, J.C., RIKER-COLEMAN, K. & GALLUP, C. (2004) - Drowned carbonate platforms in the Huon Gulf, Papua New Guinea. Geochemistry Geophysics Geosystems, 5, p. Q11008, doi: 10.1029/2004GC000726. TORTORICI, G., BIANCA, M., DE GUIDI, G., MONACO, C. & TORTORICI, L. (2003) - Fault activity and marine terracing in the Capo Vaticano area (southern Calabria) during the Middle-Late Quaternary. Quatern. Int., 101–102, 269–27

Active shape correction of a thin glass/plastic X-ray mirror

Optics for future X-ray telescopes will be characterized by very large aperture and focal length, and will be made of lightweight materials like glass or plastic in order to keep the total mass within acceptable limits. Optics based on thin slumped glass foils are currently in use in the NuSTAR telescope and are being developed at various institutes like INAF/OAB, aiming at improving the angular resolution to a few arcsec HEW. Another possibility would be the use of thin plastic foils, being developed at SAO and the Palermo University. Even if relevant progresses in the achieved angular resolution were recently made, a viable possibility to further improve the mirror figure would be the application of piezoelectric actuators onto the non-optical side of the mirrors. In fact, thin mirrors are prone to deform, so they require a careful integration to avoid deformations and even correct forming errors. This however offers the possibility to actively correct the residual deformation. Even if other groups are already at work on this idea, we are pursuing the concept of active integration of thin glass or plastic foils with piezoelectric patches, fed by voltages driven by the feedback provided by X-rays, in intra-focal setup at the XACT facility at INAF/OAPA. In this work, we show the preliminary simulations and the first steps taken in this project

Thermodynamic symmetry resolved entanglement entropies in integrable systems

We develop a general approach to compute the symmetry-resolved Rényi and von Neumann entanglement entropies (SREE) of thermodynamic macrostates in interacting integrable systems. Our method is based on a combination of the thermodynamic Bethe ansatz and the Gärtner-Ellis theorem from large deviation theory. We derive an explicit simple formula for the von Neumann SREE, which we show to coincide with the thermodynamic Yang-Yang entropy of an effective macrostate determined by the charge sector. Focusing on the XXZ Heisenberg spin chain, we test our result against iTEBD calculations for thermal states, finding good agreement. As an application, we provide analytic predictions for the asymptotic value of the SREE following a quantum quench

Transcranial Magnetic Resonance Imaging-Guided Focused Ultrasound Treatment at 1.5 T: A Retrospective Study on Treatment- and Patient-Related Parameters Obtained From 52 Procedures

Objective: To present a retrospective analysis of patient- and sonication-related parameters of a group of patients treated with a transcranial magnetic resonance imaging (MRI)-guided focused ultrasound (tcMRgFUS) system integrated with a 1.5-T MRI unit. Methods: The data obtained from 59 patients, who underwent the tcMRgFUS procedure from January 2015 to April 2019, were retrospectively reviewed for this study. The following data, among others, were mainly collected: skull density ratio (SDR), skull area (SA), number of available transducer elements (Tx), and estimated focal power at target (FP). For each of the four different treatment stages, we calculated the number of sonication processes (S-n), user-defined sonication power (S-p), effective measured power (S-mp), sonication duration (S-d), user-defined energy (E), effective measured energy (E-m), maximum temperature (T-max), and MR thermometry plane orientation. Furthermore, the time delay between each sonication (S-t) and the total treatment time (T-t) were recorded. Results: Fifty-two patients (40 males and 12 females; age 64.51 +/- SD 11.90 years; range 26-86 years), who underwent unilateral Vim thalamotomy (left = 50, 96.15%; right = 2, 3.85%) for medication-refractory essential tremor (n = 39; 78%) or Parkinson tremor (n = 13; 22%) were considered. A total of 1,068 (95.10%) sonication processes were included in our final analysis (average S-n per treatment: 20.65 +/- 6.18; range 13-41). The energy released onto the planned target was found to decrease with the SDR for all temperature ranges. A positive correlation was observed between the slope of T-max vs. E-m plot and the SDR (R-2 = 0.765; p < 0.001). In addition, the T-max was positively correlated with SDR (R-2 = 0.398; p < 0.005). On the contrary, no significant correlation was found between SDR and SA or Tx. An analysis of the MR thermometry scanning plane indicated that, at our site, the axial and the coronal planes were used (on average) 10.4 (SD +/- 3.8) and 7.7 (SD +/- 3.0) times, respectively, whereas the sagittal plane was used only 2.5 (SD +/- 3.0) times per treatment. Conclusion: Our results confirm the factors that significantly influence the course of a tcMRgFUS procedure even when a 1.5-T MRI scanner is used for procedure guidance. The experience we gained in this study indicates that the SDR remains one of the most significant technical parameters to be considered in a tcMRgFUS procedure. The possibility of prospectively setting the sonication energy according to the presented curves of energy delivery as a function of SDR for each treatment stage could provide a further understanding and a greater awareness of this emerging technology

Full counting statistics in the gapped XXZ spin chain

We exploit the knowledge of the entanglement spectrum in the ground state of the gapped XXZ spin chain to derive asymptotic exact results for the full counting statistics of the transverse magnetisation in a large spin block of length \u2113. We found that for a subsystem of even length the full counting statistics is Gaussian, while for odd subsystems it is the sum of two Gaussian distributions. We test our analytic predictions with accurate tensor networks simulations. As a byproduct, we also obtain the symmetry (magnetisation) resolved entanglement entropies

Ampiezza e tassi dei movimenti verticali a Capo Vaticano (Calabria occidentale,Italia) negli ultimi 20 mila anni determinati sulla base di cunei progradanti epiattaforme di abrasione.

Ampiezza e tassi dei movimenti tettonici verticali sono stati quantificati nel settore offshore di Capo Vaticano (Calabria occidentale), nell’intervallo Pleistocene superiore – Olocene, sulla base delle profondità del ciglio dei cunei progradanti infralitorali e delle piattaforme di abrasione formatesi durante l’ultimo massimo glaciale (LGM). I cunei progradanti sono stati riconosciuti in profili sismici a riflessione ad alta risoluzione Sparker. I dati sismici sono stati acquisiti lungo la piattaforma e la scarpata continentale superiore, durante le crociere oceanografiche Marisk 2010 e 2012 organizzate dall’IAMC del CNR di Napoli, il DISTEM dell’Università di Palermo e il Dip. di Scienze della Terra dell’Università di Napoli. La deformazione tettonica verticale del promontorio di Capo Vaticano e del suo prolungamento offshore è caratterizzata da una marcata asimmetria, con profondità dei cigli dei cunei infralitorali che si approfondisce progressivamente procedendo verso NE. La rimozione della componente non tettonica dei movimenti verticali, ottenuta utilizzando dati sulle variazioni glacio-eustatiche del tardo Quaternario [Lambeck et al., 2011], indica nell’area in esame ~11 (± 5) m di sollevamento e di ~25 (± 5) m di subsidenza, nell’intervallo post-LGM, muovendoci da sud-ovest verso nord-est, su una distanza di ~22 km. Il valore medio del tasso di sollevamento e di subsidenza (considerando la componente sia regionale sia locale) per gli ultimi 20.350 (± 1,35) anni sono pari a 0,52 (± 0,28) mm/anno e di 1,23 (± 0,32) mm/anno, rispettivamente. I valori dell’ampiezza e il pattern dei movimenti verticali ottenuti attraverso l’analisi dei cunei progradanti infralitorali sono comparabili, sebbene a tassi parzialmente differenti, sia con quelli determinati attraverso marker geomorfologici tardo Olocenici [Spampinato et al., 2012] che con i tassi di sollevamento a lungo termine calcolati sulla base delle posizioni dei terrazzi marini formatisi a 80 a 215 mila anni [Cucci & Tertulliani, 2010]. L’integrazione dei nuovi dati con quelli disponibili in letteratura indica che il basculamento del promontorio di Capo Vaticano è episodico ed è avvenuto principalmente tra 215 e 125 mila anni e nel post-LGM