Panneli aeronautici rinforzati con parti estruse saldatemediante FSW: caratterizzazionemeccanica

La Friction StirWelding (FSW) è una delle tecniche di giunzione più interessanti per l’industria aeronautica poiché,essendo un processo di saldatura allo stato solido, permette di superare tutti i problemi conosciuti collegati alletrasformazioni di fase dei processi di giunzione allo stato fuso. Tale tecnica, inoltre, permette di ridurre il peso nelleaerostrutture se comparate a quelle ottenute mediante la tecnologia del rivettamento. In questo lavoro viene presentatauna caratterizzazione meccanica di un componente ottenuto con tecnologia FSWmediante giunzioni sovrapposte (lap).Il campione simula un pannello bulkhead, ossia un pannello che separa un ambiente pressurizzato di un aeromobile(ad esempio la cabina) da ambienti non pressurizzati (ad esempio la stiva). Tali pannelli (skin) sono usualmenteirrigiditi da parti estruse rivettate sul pannello stesso (stringer). In questo caso le parti estruse, con una sezione a formadi T, sono state giuntate al pannello tramite FSWcon configurazione lap sui due lembi di appoggio. Le condizioni dicarico sono state scelte per simulare due condizioni operative reali: tensione circonferenziale (hoop stress) e trazioneperpendicolare al piano difissaggio (T-pull). I risultati permettono di apprezzare il buon comportamento atteso dalsimulatore. Una caratteristica specifica delle giunzioni in configurazione a sovrapposizione (FSWLap), ossia il difettoad uncino (hook defect), gioca un ruolo significativo nelle rotture osservate durante i test statici e nel fenomeno diinnesco delle cricche durante i test ciclici. I risultati indicano che l’attenzione dovrebbe essere focalizzata sul settaggiodei parametri di processo al fine di minimizzare il verificarsi dell’hook defect

Dynamics of Non-adiabatic Charged Cylindrical Gravitational Collapse

This paper is devoted to study the dynamics of gravitational collapse in the Misner and Sharp formalism. We take non-viscous heat conducting charged anisotropic fluid as a collapsing matter with cylindrical symmetry. The dynamical equations are derived and coupled with the transport equation for heat flux obtained from the M$\ddot{u}$ller-Israel-Stewart causal thermodynamic theory. We discuss the role of anisotropy, electric charge and radial heat flux over the dynamics of the collapse with the help of coupled equation.Comment: 15 pages, accepted for publication in Astrophys. Space Sc

Biometrics measurements in Red foxes (Vulpes vulpes) in the Picentini area. Discussion and conclusions

Techniques for assigning individual to age-classes and/or distinguish between sexes are necessary to understand population dynamics and behavioral interactions of Red foxes (Vulpes vulpes). Many studies have focused on separating juveniles from adults; age of captured live pups can be estimated from morphological changes, hind foot (HF) length, zygomatic (Z) width and body weight1. Methods that avoid capturing the animals would be particularly useful, but none is available. In this paper biometric differences between young adults and adults subjects and between sexes are investigated. Lower canine length (LCL), lower canine width (LCW), condilo-basal (CB) and scapular length resulted smaller than female adults, whereas male young adults had withers height, occipito-coccygeal (OC), ear length, and upper canine width (UCW) smaller than male adults. Almost all the parameters included in this study confirmed sexual dimorphism and some of the differences already present in young adults gained significance (from P<0.05 to P<0.01) in the adult foxes. In particular bodyweight, OC length, withers height, ear length, upper canine length and LCL, scapular and mandibular length, and inter-carnassial (IC) and Z width were significantly greater in male than in female adult foxes (P<0.01). Nasal-occipitalis (NO) length, total length, UCW and LCW, and upper dentition (UD) were significantly greater in male than in female adult foxes, as well (P<0.05). The low number of subjects included in each category, strictly due to hunting season, did not allow estimating an accurate range for the biometrics measurements performed and probably biased recordings, producing some contradictory results. Fox size varies geographically, thus mean adults measurements should be determined for each area in which they have to be applied1. HF method has been demonstrated to be an accurate method for assessing age of pups1; our data suggest that it might be as efficient in young adults, at least in female subjects. On the other hand, our results confirm the sexual dimorphism in the canine region to be higher than in the carnassial region (data not shown in our results)

Dynamics of Viscous Dissipative Plane Symmetric Gravitational Collapse

We present dynamical description of gravitational collapse in view of Misner and Sharp's formalism. Matter under consideration is a complicated fluid consistent with plane symmetry which we assume to undergo dissipation in the form of heat flow, radiation, shear and bulk viscosity. Junction conditions are studied for a general spacetime in the interior and Vaidya spacetime in the exterior regions. Dynamical equations are obtained and coupled with causal transport equations derived in context of M$\ddot{u}$ller Israel Stewart theory. The role of dissipative quantities over collapse is investigated.Comment: 17 pages, accepted for publication in Gen. Relativ. Gra

Nature of singularity formed by the gravitational collapse in Husain space-time with electromagnetic field and scalar field

In this work, we have investigated the outcome of gravitational collapse in Husain space-time in the presence of electro-magnetic and a scalar field with potential. In order to study the nature of the singularity, global behavior of radial null geodesics have been taken into account. The nature of singularities formed has been thoroughly studied for all possible variations of the parameters. These choices of parameters has been presented in tabular form in various dimensions. It is seen that irrespective of whatever values of the parameters chosen, the collapse always results in a naked singularity in all dimensions. There is less possibility of formation of a black hole. Hence this work is a significant counterexample of the cosmic censorship hypothesis.Comment: 9 pages, 19 figure

An umbrella review of candidate predictors of response, remission, recovery, and relapse across mental disorders

We aimed to identify diagnosis-specific/transdiagnostic/transoutcome multivariable candidate predictors (MCPs) of key outcomes in mental disorders. We conducted&nbsp;an umbrella review (protocol&nbsp; link ), searching MEDLINE/Embase (19/07/2022), including systematic reviews of studies reporting on MCPs of response, remission, recovery, or relapse, in DSM/ICD-defined mental disorders. From published predictors, we filtered MCPs, validating MCP criteria. AMSTAR2/PROBAST measured quality/risk of bias of systematic reviews/individual studies. We included 117 systematic reviews, 403 studies, 299,888 individuals with mental disorders, testing 796 prediction models. Only 4.3%/1.2% of the systematic reviews/individual studies were at low risk of bias. The most frequently targeted outcome was remission (36.9%), the least frequent was recovery (2.5%). Studies mainly focused on depressive (39.4%), substance-use (17.9%), and schizophrenia-spectrum (11.9%) disorders. We identified numerous MCPs within disorders for response, remission and relapse, but none for recovery. Transdiagnostic MCPs of remission included lower disease-specific symptoms (disorders = 5), female sex/higher education (disorders = 3), and&nbsp;quality of life/functioning (disorders = 2). Transdiagnostic MCPs of relapse included higher disease-specific symptoms (disorders = 5), higher depressive symptoms (disorders = 3), and younger age/higher anxiety symptoms/global illness severity/ number of previous episodes/negative life events (disorders = 2). Finally, positive trans-outcome MCPs for depression included less negative life events/depressive symptoms (response, remission, less relapse), female sex (response, remission) and better functioning (response, less relapse); for schizophrenia, less positive symptoms/higher depressive symptoms (remission, less relapse); for substance use disorder, marital status/higher education (remission, less relapse). Male sex, younger age, more clinical symptoms and comorbid mental/physical symptoms/disorders were poor prognostic factors, while positive factors included social contacts and employment, absent negative life events, higher education, early access/intervention, lower disease-specific and comorbid mental and physical symptoms/conditions, across mental disorders. Current data limitations include high risk of bias of studies and extraction of single predictors from multivariable models. Identified MCPs can inform future development, validation or refinement of prediction models of key outcomes in mental disorders

Superinfection exclusion and the long-term survival of honey bees in Varroa-infested colonies

Over the past 50 years, many millions of European honey bee (Apis mellifera) colonies have died as the ectoparasitic mite, Varroa destructor, has spread around the world. Subsequent studies have indicated that the mite's association with a group of RNA viral pathogens (Deformed Wing Virus, DWV) correlates with colony death. Here, we propose a phenomenon known as superinfection exclusion that provides an explanation of how certain A. mellifera populations have survived, despite Varroa infestation and high DWV loads. Next-generation sequencing has shown that a non-lethal DWV variant 'type B' has become established in these colonies and that the lethal 'type A' DWV variant fails to persist in the bee population. We propose that this novel stable host-pathogen relationship prevents the accumulation of lethal variants, suggesting that this interaction could be exploited for the development of an effective treatment that minimises colony losses in the future.The ISME Journal advance online publication, 27 October 2015; doi:10.1038/ismej.2015.186