What causes the fragmentation of debris streams in TDEs?

A tidal disruption event (TDE) occurs when a star passes too close to a supermassive black hole and gets torn apart by its gravitational tidal field. After the disruption, the stellar debris form an expanding gaseous stream. The morphology and evolution of this stream is particularly interesting as it ultimately determines the observational properties of the event itself. In this work we perform 3D hydrodynamical simulations of the TDE of a star modelled as a polytropic sphere of index {\gamma} = 5/3, and study the gravitational stability of the resulting gas stream. We provide an analytical solution for the evolution of the stream in the bound, unbound and marginally bound case, that allows us to describe the stream properties and analyse the time-scales of the physical processes involved, applying a formalism developed in star formation context. Our results are that, when fragmentation occurs, it is fueled by the failure of pressure in supporting the gas against its self-gravity. We also show that a stability criterion that includes also the stream gas pressure proves to be far more accurate than one that only considers the black hole tidal forces, giving analytical predictions of the time evolution of the various forces associated to the stream. Our results point out that fragmentation occurs on timescales longer compared with the observational windows of these events and is thus not expected to give rise to significant observational features.Comment: 12 pages,15 figures, accepted for publication in MNRA

Extracapsular Tonsillectomy versus Intracapsular Tonsillotomy in Paediatric Patients with OSAS

Objective: The objective of our study was to compare our experience of intracapsular tonsillotomy performed with the help of a microdebrider usually used for adenoidectomy with results obtained from extracapsular surgery through dissection and from adenoidectomy in cases of people affected with OSAS, linked to adeno-tonsil hypertrophy, observed and treated in the last 5 years. Methods: 3127 children with adenotonsillar hyperplasia and OSAS-related clinical symptoms (aged between 3 and 12 years) underwent tonsillectomy and/or adenoidectomy. A total of 1069 patients (Group A) underwent intracapsular tonsillotomy, while 2058 patients (Group B) underwent extracapsular tonsillectomy, from January 2014 to June 2018. The parameters considered in order to evaluate the effectiveness of the two different surgery techniques taken into consideration were as follows: the presence of possible postoperative complications, represented mainly by pain and perioperative bleeding; the level of postoperative respiratory obstruction compared with the original obstruction through night pulse oximetry, performed 6 months before and after the surgery; tonsillar hypertrophy relapse in Group A and/or the presence of residues in Group B with clinical evaluation performed 1 month, 6 months, and 1 year after the surgery; and postoperative life quality, evaluated through submitting to parents the same survey proposed before the surgery 1 month, 6 months, and 1 year after the surgery. Results: Regardless of the technique used (extracapsular tonsillectomy or intracapsular tonsillotomy), there was a clear improvement in both the obstructive respiratory symptomatology and quality of life in both patient groups, as highlighted by the pulse oximetry and the OSA-18 survey submitted later. Conclusions: Intracapsular tonsillotomy surgery has improved in terms of a reduction in postoperative bleeding cases and pain reduction, with an earlier return to patients’ usual lifestyle. Lastly, using a microdebrider with the intracapsular technique seems to be particularly effective in removing most of the tonsillar lymphatic tissue, leaving only a thin border of pericapsular lymphoid tissue and preventing lymphoid tissue regrowth during one year of follow-up

EFFECTIVENESS OF VACUUM DEVICES FOR HOME STORAGE OF RAINBOW TROUTS FROM GAME FISHING LAKES

The aim of this work was to study the effectiveness of vacuum devices for home storage of rainbow trouts from sport fishing lakes located near Avellino, in the South of Italy. The trout were divided in two groups: one was vacuum-packaged by using a "Food Vacuum System", while the other was stored in plastic trays covered with plastic wrap. Both the fish samples were stored at 4°C for 6 days. Rainbow trout purchased in a local supermarket were used as control. The trout quality was evaluated by microbiological, chemical and sensory analyses. Fatty acids and volatile compounds were characterized by GC and SPME-GC/MS. Results proved the efficiency of the vacuum system in preserving the quality characteristics of the trout, limiting the formation of off-odors and off-flavors related to spoilage and oxidative processes

Dynamics of a hybrid morphing wing with active open loop vibrating trailing edge by Time-Resolved PIV and force measures

A quantitative characterization of the effects obtained by high frequency-low amplitude trailing edge actuation is presented. Particle image velocimetry, pressure and aerodynamic forces measurements are carried out on a wing prototype equipped with shape memory alloys and trailing edge piezoelectric-actuators, allowing simultaneously high deformations (bending) in low frequency and higher-frequency vibrations. The effects of this hybrid morphing on the forces have been quantified and an optimal actuation range has been identified, able to increase lift and decrease drag. The present study focuses more specifically on the effects of the higher-frequency vibrations of the trailing edge region. This actuation allows manipulation of the wake turbulent structures. It has been shown that specific frequency and amplitude ranges achieved by the piezoelectric actuators are able to produce a breakdown of larger coherent eddies by means of upscale energy transfer from smaller-scale eddies in the near wake. It results a thinning of the shear layers and the wake's width, associated to reduction of the form drag, as well as a reduction of predominant frequency peaks of the shear-layer instability. These effects have been shown by means of frequency domain analysis and Proper Orthogonal Decomposition

Endothelial Progenitor Cell-Based in vitro Pre-Endothelialization of Human Cell-Derived Biomimetic Regenerative Matrices for Next-Generation Transcatheter Heart Valves Applications

Hemocompatibility of cardiovascular implants represents a major clinical challenge and, to date, optimal antithrombotic properties are lacking. Next-generation tissue-engineered heart valves (TEHVs) made from human-cell-derived tissue-engineered extracellular matrices (hTEMs) demonstrated their recellularization capacity in vivo and may represent promising candidates to avoid antithrombotic therapy. To further enhance their hemocompatibility, we tested hTEMs pre-endothelialization potential using human-blood-derived endothelial-colony-forming cells (ECFCs) and umbilical vein cells (control), cultured under static and dynamic orbital conditions, with either FBS or hPL. ECFCs performance was assessed via scratch assay, thereby recapitulating the surface damages occurring in transcatheter valves during crimping procedures. Our study demonstrated: feasibility to form a confluent and functional endothelium on hTEMs with expression of endothelium-specific markers; ECFCs migration and confluency restoration after crimping tests; hPL-induced formation of neo-microvessel-like structures; feasibility to pre-endothelialize hTEMs-based TEHVs and ECFCs retention on their surface after crimping. Our findings may stimulate new avenues towards next-generation pre-endothelialized implants with enhanced hemocompatibility, being beneficial for selected high-risk patients

Asexual reproduction and strobilation of Sanderia malayensis (Scyphozoa, Pelagiidae) in relation to temperature: experimental evidence and implications

Sanderia malayensis is a scyphozoan species present in the Indian and Pacific Oceans, ranging from the Suez Canal to Japan. Although this jellyfish is commonly kept in aquariums around the world, there is a knowledge gap regarding its biology and ecology, especially at the polyp stage. In this study, we tested the asexual reproductive activity of S.malayensis at Three different temperatures: 10, 15 and 20 \ub0C. Results showed significant increases of polyps at 15 \ub0C and 20 \ub0C, and a minimum at 10\ub0C, corresponding with daily budding rates of 6.61\ub1 0.92%, 5.85 \ub1 2.36% and 0.66\ub10.24%, respectively. Moreover, a second experiment was carried out to report about the ability of S. malayensis to prey on Aurelia solida at ephyra stage. Unidirectional predation of S. malayensis ephyrae on A. solida and an absence of inverse predation was observed. These results could give new insights on the potential fitness and survival of this species if it will ever invade the Mediterranean Sea

Induction of neutralizing antibodies in CLL patients after SARS-CoV-2 mRNA vaccination: a monocentric experience

Vaccination represents the best strategy to fight COVID-19 pandemics, especially in immune compromised subjects. In chronic lymphatic leukemia patients, a marked impairment of the immune response to mRNA SARS-CoV-2 vaccine was observed. In this report, we analyzed anti-RBD and neutralizing antibodies in CLL patients after two doses of mRNA SARS CoV 2 vaccine and evaluated the impact of Bruton kinase inhibitory agents. Twenty-seven CLL patients vaccinated with mRNA vaccines against SARS CoV-2 were recruited. Serum IgG, IgM and IgA anti-RBD antibodies and neutralizing antibodies were detected, and antibody avidity was measured. Peripheral blood leukocytes subsets were evaluated by flow cytometry. After two vaccine doses anti-RBD IgG were produced in 11/27 (40.5%) of patients and levels of IgG and IgA anti RBD in CLL patients were sensibly lower than in controls. Neutralizing antibodies were detectable in 12/27 (44.5%) of the patients and their level was lower than that observed in controls. Disease burden and treatment with Bruton kinases inhibitors markedly impaired vaccine induced antibody response. However, in responder patients, antibody avidity was comparable to normal subjects, indicating that the process of clonal selection and affinity maturation takes place as expected. Taken together, these data confirm the impact of disease burden and therapy on production of anti-RBD and neutralizing antibodies and support the current policy of vaccinating CLL patients

Estratégias para sair de si ou de que vida se trata? : Aula online de atuação em tempo de pandemia

Abstract: The article analyzes pedagogical practices carried out at the university, in acting classes, in a remote environment, during the pandemic. Students were invited to reflect on the attentional regimes most operative in contemporary society and investigate, in their homes and everyday spaces, a different perception regime structured around silence, pause, dilated time, and getting out of oneself and moving towards others. The individual creative experiences born in this new attentional environment were collectively analyzed, transforming the classroom into a laboratory where art appeared as a propitious place to imagine other worlds, less violent, individualistic, and anthropocentric.El artículo analiza las prácticas pedagógicas realizadas en la universidad, en clases de actuación escénica, en un entorno online, durante el período de la pandemia. Se invitó a los estudiantes a reflexionar sobre los regímenes atencionales más operativos en la sociedad contemporánea, e investigar, en sus hogares y espacios cotidianos, un régimen de percepción diferente, estructurado en torno al silencio, la pausa, la prolongación del tiempo y la salida de sí mismo en dirección a los demás. Las experiencias creativas individuales generadas en este nuevo entorno atencional fueron analizadas colectivamente, transformando la clase en laboratorio donde el arte apareció como un lugar propicio a la imaginación de otros mundos menos violentos, individualistas y antropocéntricos.O artigo analisa práticas pedagógicas realizadas na universidade, em aulas de atuação cênica, em ambiente remoto, no período pandêmico. Os estudantes foram convidados a refletir sobre os regimes atencionais mais operantes na sociedade contemporânea, e a investigar, em suas casas e espaços cotidianos, um regime de percepção outro, estruturado em torno do silêncio, da paragem, do alargamento do tempo e da saída de si mesmo na direção dos outros. As experiências criativas individuais gestadas nesse novo ambiente atencional foram analisadas coletivamente, transformando a sala de aula em um laboratório onde a arte se apresentava como um lugar propício à imaginação de mundos outros, menos violentos, individualistas e antropocentrados

Three-Dimensional Simulation of a Complete Vertical Axis Wind Turbine Using Overlapping Grids

Three-dimensional simulations of the aerodynamic field around a three-blade straight-axis Vertical Axis Wind Turbine (VAWT) are presented for two values of the Tip Speed Ratio λ (TSR), namely λ=1.52 and λ=2.5. Numerical simulations were carried out using the over-set grid solver ROSITA (ROtorcraft Software ITAly). The Reynolds-Averaged Navier-Stokes equations are completed by the Spalart-Allmaras turbulence model. A strong interaction between the blade and the blade wakes is evidenced. Dynamic stall is observed in the case λ=2.5. The computed flow-field presents diverse three-dimensional effects, including the interaction between the blades and the tip vortices and the aerodynamic disturbances from the turbine shaft and the support arms. Three-dimensional effects are more relevant for λ=2.5. The comparison to experimental data confirms the general features of the flow