An automatic deep learning approach for coronary artery calcium segmentation

Coronary artery calcium (CAC) is a significant marker of atherosclerosis and cardiovascular events. In this work we present a system for the automatic quantification of calcium score in ECG-triggered non-contrast enhanced cardiac computed tomography (CT) images. The proposed system uses a supervised deep learning algorithm, i.e. convolutional neural network (CNN) for the segmentation and classification of candidate lesions as coronary or not, previously extracted in the region of the heart using a cardiac atlas. We trained our network with 45 CT volumes; 18 volumes were used to validate the model and 56 to test it. Individual lesions were detected with a sensitivity of 91.24%, a specificity of 95.37% and a positive predicted value (PPV) of 90.5%; comparing calcium score obtained by the system and calcium score manually evaluated by an expert operator, a Pearson coefficient of 0.983 was obtained. A high agreement (Cohen's k = 0.879) between manual and automatic risk prediction was also observed. These results demonstrated that convolutional neural networks can be effectively applied for the automatic segmentation and classification of coronary calcifications

Crossing Over from Attractive to Repulsive Interactions in a Tunneling Bosonic Josephson Junction

We explore the interplay between tunneling and interatomic interactions in the dynamics of a bosonic Josephson junction. We tune the scattering length of an atomic $^{39}$K Bose-Einstein condensate confined in a double-well trap to investigate regimes inaccessible to other superconducting or superfluid systems. In the limit of small-amplitude oscillations, we study the transition from Rabi to plasma oscillations by crossing over from attractive to repulsive interatomic interactions. We observe a critical slowing down in the oscillation frequency by increasing the strength of an attractive interaction up to the point of a quantum phase transition. With sufficiently large initial oscillation amplitude and repulsive interactions the system enters the macroscopic quantum self-trapping regime, where we observe coherent undamped oscillations with a self-sustained average imbalance of the relative well population. The exquisite agreement between theory and experiments enables the observation of a broad range of many body coherent dynamical regimes driven by tunable tunneling energy, interactions and external forces, with applications spanning from atomtronics to quantum metrology.Comment: 10 pages, 8 figures, supplemental materials are include

Sub-Doppler laser cooling of potassium atoms

We investigate sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of systems and an adiabatic ramping of the laser parameters allows to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25(3)microK and 47(5)microK in high-density samples of the two isotopes 39K and 41K, respectively. Our findings will find application to other atomic systems.Comment: 7 pages, 9 figure

EUV emission lines and diagnostics observed with Hinode/EIS

Quiet Sun and active region spectra from the Hinode/EIS instrument are presented, and the strongest lines from different temperature regions discussed. A list of emission lines recommended to be included in EIS observation studies is presented based on analysis of blending and diagnostic potential using the CHIANTI atomic database. In addition we identify the most useful density diagnostics from the ions covered by EIS.Comment: 14 pages, 3 figures, submitted to PASJ Hinode first results issu

Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions

New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (APEC), which uses atomic data in the companion Astrophysical Plasma Emission Database (APED) to calculate spectral models for hot plasmas. APED contains the requisite atomic data such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths. We compare the APEC results to other plasma codes for hydrogen- and helium-like diagnostics, and test the sensitivity of our results to the number of levels included in the models. We find that dielectronic recombination with hydrogen-like ions into high (n=6-10) principal quantum numbers affects some helium-like line ratios from low-lying (n=2) transitions.Comment: 5 pages, 6 figures, accepted by ApJ Letter

L’influenza dell’attaccamento e della sensibilità diadica genitorialesullo sviluppo psicomotorio del bambino nato pretermine

Lo scopo di questa ricerca è studiare i precursori dell’attaccamento e la sensibilità diadica genitoriale nelle famiglie con bambino nato pretermine. Sono state considerate 110 famiglie delle quali 55 con figli nati pretermine ( peso alla nascita < 1500 gr.) per un totale di 330 soggetti valutati durante i primi sei mesi di età corretta del bambino. Le diadi madre-bambino e padre-bambino sono state sottoposte al CARE-Index, una procedura videoregistrata per la valutazione dei precursori dell’attaccamento; ad entrambi i genitori sono stati somministrati CES-D, per la valutazione della depressione e STAI Y-2, per la valutazione dell’ansia di tratto. Lo sviluppo psicomotorio dei neonati è stato valutato tramite le scale Bayley. Rispetto ai controlli, nelle madri dei bambini pretermine sono stati evidenziati bassi punteggi di Sensibilità Diadica al CARE-Index (p=.025) ed elevati livelli di ansia (p=.026). Nei padri sono stati riscontrati bassi punteggi di Sensibilità Diadica (p=.004) e alti livelli di sintomi depressivi (p=.003). Nelle famiglie pretermine i precursori dell’attaccamento sono più frequentemente di tipo insicuro nelle madri (p=.000) e nei padri (p=.000), mentre nei neonati solo nell’interazione con la madre (p=012). Questi fattori sono risultati associati a minori punteggi alle scale Bayley (p=.000). Nelle madri dei neonati pretermine si riscontrano frequenti difficoltà con la famiglia di origine, nei padri una percezione negativa del proprio bambino e una maggiore insoddisfazione per l’assistenza ricevuta. Questi risultati evidenziano che il 40% delle madri e il 75% dei padri dei bambini nati pretermine rientra nella fascia ad alto rischio del CARE-Index (che richiede un trattamento psicologico e/o farmacologico). In tali casi, la scarsa sensibilità diadica, i precursori di attaccamento insicuro e le difficoltà psicologiche dei genitori sembrano influenzare lo sviluppo psicomotorio del bambino

Superflares on Ordinary Solar-Type Stars

Short duration flares are well known to occur on cool main-sequence stars as well as on many types of `exotic' stars. Ordinary main-sequence stars are usually pictured as being static on time scales of millions or billions of years. Our sun has occasional flares involving up to $\sim 10^{31}$ ergs which produce optical brightenings too small in amplitude to be detected in disk-integrated brightness. However, we identify nine cases of superflares involving $10^{33}$ to $10^{38}$ ergs on normal solar-type stars. That is, these stars are on or near the main-sequence, are of spectral class from F8 to G8, are single (or in very wide binaries), are not rapid rotators, and are not exceedingly young in age. This class of stars includes many those recently discovered to have planets as well as our own Sun, and the consequences for any life on surrounding planets could be profound. For the case of the Sun, historical records suggest that no superflares have occurred in the last two millennia.Comment: 16 pages, accepted for publication in Ap

Development status of a Laue lens project for gamma-ray astronomy

We report the status of the HAXTEL project, devoted to perform a design study and the development of a Laue lens prototype. After a summary of the major results of the design study, the approach adopted to develop a Demonstration Model of a Laue lens is discussed, the set up described, and some results presented.Comment: 11 pages, 11 figures, 2007 SPIE Conference on Optics for EUV, X-Ray, and Gamma-Ray Astronomy II

Measurement of tissue oxygenation in isolated rat hearts using near infrared spectroscopy

New techniques involving Near Infrared Spectroscopy (NIRS) and imaging are rapidly evolving for a large number of new clinical applications. These techniques, based upon nearinfrared light transmission through biological tissue, aim to monitor the hemoglobin and myoglobin concentration changes due to particular physiological state. Clinical applications regard, for instance, the monitoring of muscles and cerebral oxygenation, functional brain activation studies and heart perfusion research. Recently, some works presented tissue oxygenation studies in beating or arrested isolated porcine hearts. In our work we present the design and realization of a dedicated NIRS system for the myocardial perfusion analysis of isolated, saline solution perfused beating rat hearts; in this case the absence of blood allows for unambiguous measurement of tissue myoglobin oxygenation. The presented prototype is portable, low cost, battery operated and permits the measurement of both oxy and deoxy myoglobin concentration changes during imposed regional or global ischemia and reperfusion