On the Wilson-Bappu relationship in the Mg II k line

An investigation is carried out on the Wilson-Bappu effect in the Mg II k line at 2796.34 A. The work is based on a selection of 230 stars observed by both the IUE and HIPPARCOS satellites, covering a wide range of spectral type and absolute visual magnitudes. The Wilson-Bappu relationship here provided is considered to represent an improvement over previous recent results for the considerably larger data sample used as well as for a proper consideration of the measurement errors. No evidence has been found for a possible dependence of the WB effect on stellar metallicity and effective temperature.Comment: 8 pages, 8 figures Accepted for publication on A&

A study of the Mg II 2796.34 A emission line in late--type normal, and RS CVn stars

We carry out an analysis of the Mg II 2796.34 A emission line in RS CVn stars and make a comparison with the normal stars studied in a previous paper (Paper I). The sample of RS CVn stars consists of 34 objects with known HIPPARCOS parallaxes and observed at high resolution with IUE. We confirm that RS CVn stars tend to possess wider Mg II lines than normal stars having the same absolute visual magnitude. However, we could not find any correlation between the logarithmic line width log Wo and the absolute visual magnitude Mv (the Wilson--Bappu relationship) for these active stars, contrary to the case of normal stars addressed in Paper I. On the contrary, we find that a strong correlation exists in the (Mv, log L) plane (L is the absolute flux in the line). In this plane, normal and RS CVn stars are distributed along two nearly parallel straight lines with RS CVn stars being systematically brighter by about 1 dex. Such a diagram provides an interesting tool to discriminate active from normal stars. We finally analyse the distribution of RS CVn and of normal stars in the (log L, log Wo) plane, and find a strong linear correlation for normal stars, which can be used for distance determinations.Comment: 10 pages, 7 figures, latex, to be published in A&

Stochastic simulation of destruction processes in self-irradiated materials

Self-irradiation damages resulting from fission processes are common phenomena observed in nuclear fuel containing (NFC) materials. Numerous $\alpha$-decays lead to local structure transformations in NFC materials. The damages appearing due to the impacts of heavy nuclear recoils in the subsurface layer can cause detachments of material particles. Such a behaviour is similar to sputtering processes observed during a bombardment of the material surface by a flux of energetic particles. However, in the NFC material, the impacts are initiated from the bulk. In this work we propose a two-dimensional mesoscopic model to perform a stochastic simulation of the destruction processes occurring in a subsurface region of NFC material. We describe the erosion of the material surface, the evolution of its roughness and predict the detachment of the material particles. Size distributions of the emitted particles are obtained in this study. The simulation results of the model are in a qualitative agreement with the size histogram of particles produced from the material containing lava-like fuel formed during the Chernobyl nuclear power plant disaster.Comment: 11 pages, 8 figure

Entropy: From Black Holes to Ordinary Systems

Several results of black holes thermodynamics can be considered as firmly founded and formulated in a very general manner. From this starting point we analyse in which way these results may give us the opportunity to gain a better understanding in the thermodynamics of ordinary systems for which a pre-relativistic description is sufficient. First, we investigated the possibility to introduce an alternative definition of the entropy basically related to a local definition of the order in a spacetime model rather than a counting of microstates. We show that such an alternative approach exists and leads to the traditional results provided an equilibrium condition is assumed. This condition introduces a relation between a time interval and the reverse of the temperature. We show that such a relation extensively used in the black hole theory, mainly as a mathematical trick, has a very general and physical meaning here; in particular its derivation is not related to the existence of a canonical density matrix. Our dynamical approach of thermodynamic equilibrium allows us to establish a relation between action and entropy and we show that an identical relation exists in the case of black holes. The derivation of such a relation seems impossible in the Gibbs ensemble approach of statistical thermodynamics. From these results we suggest that the definition of entropy in terms of order in spacetime should be more general that the Boltzmann one based on a counting of microstates. Finally we point out that these results are obtained by reversing the traditional route going from the Schr\"{o}dinger equation to statistical thermodynamics

The real-time earthquake monitoring system in Italy

As regards the transmission vectors – one of the most critical points of a seismic network – we adopted a mixed strategy: half of the stations are connected through satellite links, and half through cable links. The use of satellite transmission presents several advantages: the link is very robust, the constraints for site selection are weak, and the cost is lower than telephone lines. As regards the terrestrial cable links, we use INGV digitizers (named GAIA), protected IP connections of the Italian Public Administration Network (RUPA): site selection is more delicate, and a compromise must be found between low environmental noise and availability of network infrastructures

Brafv600e and Ctbn1 Mutational Study in Rathke's Cleft Cysts

Aim: Rathke's cleft cysts and craniopharyngiomas tipically involve sellar region and their histogenetic relationship is still matter of debate. Clinical and histopathologic differentiation of cystic lesions from the sellar region, that is, craniopharyngiomas (CPs) and Rathke cleft cysts (RCCs), is challenging and has great importance with respect to variable clinical manifestation and adapted surgical treatment strategies in both entities. The recent acquisition that adamantinomatous and papillary craniopharyngiomas bear distinct molecular alterations i.e., β-catenin (CTNNB1) and BRAFv600 mutations respectively, has suggest to screen for such alteration a series of Rathke cyst to seek a possible relation with one of the two craniopharyngioma type. Methods: Seven Rathke's cleft cysts were analyzed for BRAF and CTNNB1 mutational status by sequencing and immunohistochemistry. Radiological, clinical and histological features were performed. Results: None of the 7 Rathke's cleft cysts harbor BRAFV600E mutation. No CTNNB1 mutation was found. Radiological, clinical and histological re-evaluation of the cases confirmed the diagnosis of Rathke's cleft cysts. Conclusion: BRAFV600E and CTNNB1 mutations appeared, as most reliable factor for the differentiation between purely cystic CPs and RCCs, whereas tumor location, tumor size, and radiological parameter of the tumor were less consistent parameters. This study again confirms that craniopharyngiomas (CPs) and Rathke cleft cysts (RCCs), are associated with distinct pathogenic pathways

Clinical Management of Acinic Cell Carcinoma of the Lacrimal Gland

To report a case of acinic cell carcinoma occurred in the lacrimal gland. A 59-year-old man was admitted because of sudden blurring of vision, progressive proptosis of the left eye, and mild double vision in left and down directions of the gaze (Hess-Lancaster test). His medical history detailed controlled bilateral keratoconus and open angle glaucoma. On examination, the best corrected visual acuity decreased from 8/20 till 1/50 in one week. There was a swelling of the left upper eyelid. A hard and tender mass was palpated in the superior temporal left orbit. Ultrasound scan showed an extraconal solid mass, situated in the superior lateral corner of the orbit. Computed tomography and magnetic resonance imaging (MRI) revealed a mass of two centimeters in diameter, with round well-defined outline, within the lacrimal gland. We per-formed an enucleoresection of the mass, via a coronal approach and a lateral orbitotomy by a piezosurgical device. The lesion appeared nodular, brownish, measuring about 2 7 1.5 cm. Histopathological findings were consistent with acinic cell carcinoma with a microcystic, focally papillary-cystic growth of pattern. Follow-up MRI outcomes led to removal of the residual lacrimal gland for suspicion of recurrence. No tumor recurrences where detected at 7-year follow-up

AEducaAR, Anatomical Education in Augmented Reality: A Pilot Experience of an Innovative Educational Tool Combining AR Technology and 3D Printing

Gross anatomy knowledge is an essential element for medical students in their education, and nowadays, cadaver-based instruction represents the main instructional tool able to provide three-dimensional (3D) and topographical comprehensions. The aim of the study was to develop and test a prototype of an innovative tool for medical education in human anatomy based on the combination of augmented reality (AR) technology and a tangible 3D printed model that can be explored and manipulated by trainees, thus favoring a three-dimensional and topographical learning approach. After development of the tool, called AEducaAR (Anatomical Education with Augmented Reality), it was tested and evaluated by 62 second-year degree medical students attending the human anatomy course at the International School of Medicine and Surgery of the University of Bologna. Students were divided into two groups: AEducaAR-based learning (“AEducaAR group”) was compared to standard learning using human anatomy atlas (“Control group”). Both groups performed an objective test and an anonymous questionnaire. In the objective test, the results showed no significant difference between the two learning methods; instead, in the questionnaire, students showed enthusiasm and interest for the new tool and highlighted its training potentiality in open-ended comments. Therefore, the presented AEducaAR tool, once implemented, may contribute to enhancing students’ motivation for learning, increasing long-term memory retention and 3D comprehension of anatomical structures. Moreover, this new tool might help medical students to approach to innovative medical devices and technologies useful in their future careers