An experimental study of wall-injected flows in a rectangular cylinder

An experimental investigation of the flow inside a rectangular cylinder with air injected continuously along the wall is performed. This kind of flow is a two-dimensional approximation of what happens inside a solid rocket motor, where the lateral grain burns expelling exhaust gas or in processes with air filtration or devices to attain uniform flows. We propose a brief derivation of some analytical solutions and a comparison between these solutions and experimental data, which are obtained using the Particle Image Velocimetry (PIV) technique, in order to provide a global reconstruction of the flowfield. The flow, which enters orthogonal to the injecting wall, turns suddenly its direction being pushed towards the exit of the chamber. Under the incompressible and inviscid flow hypothesis, two analytical solutions are reported and compared. The first one, known as Hart-McClure solution, is irrotational and the injection velocity is non-perpendicular to the injecting wall. The other one, due to Taylor and Culick, has non-zero vorticity and constant, vertical injection velocity. The comparison with laminar solutions is useful to assess whether transition to turbulence is reached and how the disturbance thrown in by the porous injection influences and modifies those solutions

First-Order Regular and Degenerate Identification Differential Problems

We are concerned with both regular and degenerate first-order identification problems related to systems of differential equations of weakly parabolic type in Banach spaces. Several applications to partial differential equations and systems will be given in a subsequent paper to show the fullness of our abstract results

Linear Sobolev Type Equations with Relatively -Sectorial Operators in Space of "Noises"

The concept of "white noise," initially established in finite-dimensional spaces, is transferred to infinite-dimensional case. The goal of this transition is to develop the theory of stochastic Sobolev type equations and to elaborate applications of practical interest. To reach this goal the Nelson-Gliklikh derivative is introduced and the spaces of "noises" are developed. The Sobolev type equations with relatively sectorial operators are considered in the spaces of differentiable "noises." The existence and uniqueness of classical solutions are proved. The stochastic Dzektser equation in a bounded domain with homogeneous boundary condition and the weakened Showalter-Sidorov initial condition is considered as an application

Steady states in a structured epidemic model with Wentzell boundary condition

We introduce a nonlinear structured population model with diffusion in the state space. Individuals are structured with respect to a continuous variable which represents a pathogen load. The class of uninfected individuals constitutes a special compartment that carries mass, hence the model is equipped with generalized Wentzell (or dynamic) boundary conditions. Our model is intended to describe the spread of infection of a vertically transmitted disease, for example Wolbachia in a mosquito population. Therefore the (infinite dimensional) nonlinearity arises in the recruitment term. First we establish global existence of solutions and the Principle of Linearised Stability for our model. Then, in our main result, we formulate simple conditions, which guarantee the existence of non-trivial steady states of the model. Our method utilizes an operator theoretic framework combined with a fixed point approach. Finally, in the last section we establish a sufficient condition for the local asymptotic stability of the positive steady state

Nonsymmetric elliptic operators with wentzell boundary conditions in general domains

We study nonsymmetric second order elliptic operators with Wentzell boundary conditions in general domains with sufficiently smooth boundary. The ambient space is a space of Lp-type, 1 ≤ p ≤ ∞. We prove the existence of analytic quasicontractive (C0)-semigroups generated by the closures of such operators, for any 1 ≤ p ≤ ∞. Moreover, we extend a previous result concerning the continuous dependence of these semigroups on the coefficients of the boundary condition. We also specify precisely the domains of the generators explicitly in the case of bounded domains and 1 ≤ p ≤ ∞, when all the ingredients of the problem, including the boundary of the domain, the coefficients, and the initial condition, are of class C∞

Facing the Pandemic in Italy: Personality Profiles and Their Associations With Adaptive and Maladaptive Outcomes

The negative impact of the COVID-19 pandemic on individuals’ psychosocial functioning was widely attested during the last year. However, the extent to which individual differences are associated with adaptive and maladaptive outcomes during quarantine in Italy remains largely unexplored. Using a person-oriented approach, the present study explored the association of personality profiles, based on three broad individual dispositions (i.e., positivity, irritability, and hostile rumination) and two self-efficacy beliefs in the emotional area (i.e., expressing positive emotions and regulating anger emotion), with adaptive and maladaptive outcomes during the first Italian lockdown (March–June 2020). In doing so, we focused also on how different age groups (i.e., young adults and adults) differently faced the pandemic. The study was conducted through an online survey from May to June 2020 and included 1341 participants living in Italy, divided into two groups: 737 young adults aged 18–35 and 604 adults aged 36–60 years old. Latent Profile Analysis identified three personality profiles: resilient, vulnerable, and moderate. A subsequent path analysis model showed that the resilient profile was positively associated with prosocial behavior as an indicator of adaptive outcome, and negatively associated with three maladaptive outcomes: interpersonal aggression, depressive symptoms, and anxiety problems. Contrarily, the vulnerable profile resulted negatively associated with prosocial behavior and positively associated with the three maladaptive outcomes. Finally, regarding age group differences, young adults belonging to the vulnerable profile showed a greater association especially with interpersonal aggression, depression, and anxiety problems, as compared to adults belonging to the same profile. Overall, the results of the present study highlighted the importance to analyze individual functioning during an isolation period by using a person-oriented approach. Findings evidenced the existence of three different profiles (i.e., Resilient, Vulnerable, and Moderate) and subsequent path analysis revealed, especially for the vulnerable profile and young adults, a greater maladaptive consequence of the quarantine. The practical implications will be discussed

Smartphone and social network addiction in early adolescents: The role of self-regulatory self-efficacy in a pilot school-based intervention

Background: Youths' online problematic behaviors, such as smartphone or social network sites (SNS) addiction, gained increasing attention nowadays, due to their impact on concurrent and later adjustment, such as emotional and/or behavioral problems, academic impairments, or relational issues. Aims: This study aims to evaluate the effectiveness of a pilot school-based intervention to contrast online addictive behaviors while fostering adolescents' self-regulative abilities. Materials & Methods: The intervention started in January 2022 in an Italian junior high school located in Rome, and consisted of four meetings with students. A total sample of 462 15-year-old adolescents (Mage = 15.2; SD = 0.50; 41% females; Ncontrol = 214; Nintervention = 248) was considered. Within the latent difference score framework, we examined short-term changes from the pre-to-the-postintervention levels of SNS and smartphone addiction, and self-regulatory self-efficacy (SRSE) beliefs as a possible booster of the intervention's effectiveness. Results: Results showed a significant decrease in both online addictions (SNS and smartphone addiction), controlling for age, gender, sexual orientation, and socioeconomic status, because of the short-term efficacy of the project. The buffering effect of SRSE beliefs was further supported. Conclusion: These findings emphasized the usefulness of promoting youths' self-regulative beliefs to contrast problematic tendencies, according to a Positive Youth Development perspective which focused on resources rather than only on the prevention of negative outcomes for youths' adjustment

Exploring the protective function of positivity and regulatory emotional self-efficacy in time of pandemic covid-19

Despite several empirical studies on the 2019 coronavirus disease (COVID-19) pandemic that have highlighted its detrimental effect on individuals’ mental health, the identification of psychological factors that may moderate its impact on individuals’ behavior and well-being remains partly unexplored. The present study was conceived to examine the mediation role of regulatory emotional self-efficacy in the relationship between positivity and anxiety, depression, and perceived self-efficacy in complying with the containment measures to contrast the COVID-19 spread. Furthermore, the moderation role of age was tested. A sample of 1258 participants (64.2% women; Mage = 42.09, SD = 13.62) enrolled from the Italian general population answered an online survey aimed at investigating the role of individual differences in facing the COVID-19 pandemic. We opted for a snowball recruiting procedure to find participants. The online survey was disseminated through email invitation and using social media platforms (i.e., Facebook, Instagram). A multi-group path analysis model was performed using Mplus 8.4 to explore the hypothesized relations among variables. The following criteria were employed to evaluate the goodness of fit: χ2 likelihood ratio statistic, CFI and TLI > 0.95, RMSEA < 0.06 and SRMR < 0.08. The findings corroborated the protective role of both positivity and regulatory emotional self-efficacy in reducing individuals’ anxiety and depressive symptoms, as well as in fostering individuals’ capabilities in complying with the containment measures imposed by the government to reduce the risk of illness and to contain the spread of the virus COVID-19. Specifically, regulatory emotional self-efficacy beliefs partially mediated the relations between positivity and anxiety and depressive symptoms and fully mediated the effect of positivity on perceived self-efficacy beliefs in complying with the containment measures. These paths were equal across ages. The results of the present study appear relevant to implementing psychological interventions aimed to reduce the deleterious effects of the COVID-19 pandemic on mental health through the promotion of individuals’ optimistic orientation and emotion regulation

Well-posedness for degenerate third order equations with delay and applications to inverse problems

[EN] In this paper, we study well-posedness for the following third-order in time equation with delay <disp-formula idoperators defined on a Banach space X with domains D(A) and D(B) such that t)is the state function taking values in X and u(t): (-, 0] X defined as u(t)() = u(t+) for < 0 belongs to an appropriate phase space where F and G are bounded linear operators. Using operator-valued Fourier multiplier techniques we provide optimal conditions for well-posedness of equation (0.1) in periodic Lebesgue-Bochner spaces Lp(T,X), periodic Besov spaces Bp,qs(T,X) and periodic Triebel-Lizorkin spaces Fp,qs(T,X). A novel application to an inverse problem is given.The first, second and third authors have been supported by MEC, grant MTM2016-75963-P. The second author has been supported by AICO/2016/30. The fourth author has been supported by MEC, grant MTM2015-65825-P.Conejero, JA.; Lizama, C.; Murillo-Arcila, M.; Seoane Sepúlveda, JB. (2019). Well-posedness for degenerate third order equations with delay and applications to inverse problems. Israel Journal of Mathematics. 229(1):219-254. https://doi.org/10.1007/s11856-018-1796-8S2192542291K. Abbaoui and Y. Cherruault, New ideas for solving identification and optimal control problems related to biomedical systems, International Journal of Biomedical Computing 36 (1994), 181–186.M. Al Horani and A. Favini, Perturbation method for first- and complete second-order differential equations, Journal of Optimization Theory and Applications 166 (2015), 949–967.H. Amann, Operator-valued Fourier multipliers, vector-valued Besov spaces, and applications, Mathematische Nachrichten 186 (1997), 5–56.U. A. Anufrieva, A degenerate Cauchy problem for a second-order equation. A wellposedness criterion, Differentsial’nye Uravneniya 34 (1998), 1131–1133; English translation: Differential Equations 34 (1999), 1135–1137.W. Arendt and S. Bu, The operator-valued Marcinkiewicz multiplier theorem and maximal regularity, Mathematische Zeitschrift 240 (2002), 311–343.W. Arendt and S. Bu, Operator-valued Fourier multipliers on periodic Besov spaces and applications, Proceedings of the Edinburgh Mathematical Society 47 (2004), 15–33.W. Arendt, C. Batty and S. Bu, Fourier multipliers for Holder continuous functions and maximal regularity, Studia Mathematica 160 (2004), 23–51.V. Barbu and A. Favini, Periodic problems for degenerate differential equations, Rendiconti dell’Istituto di Matematica dell’Università di Trieste 28 (1996), 29–57.A. Bátkai and S. Piazzera, Semigroups for Delay Equations, Research Notes in Mathematics, Vol. 10, A K Peters, Wellesley, MA, 2005.S. Bu, Well-posedness of second order degenerate differential equations in vector-valued function spaces, Studia Mathematica 214 (2013), 1–16.S. Bu and G. Cai, Periodic solutions of third-order degenerate differential equations in vector-valued functional spaces, Israel Journal of Mathematics 212 (2016), 163–188.S. Bu and G. Cai, Well-posedness of second-order degenerate differential equations with finite delay in vector-valued function spaces, Pacific Journal of Mathematics 288 (2017), 27–46.S. Bu and Y. Fang, Periodic solutions of delay equations in Besov spaces and Triebel–Lizorkin spaces, Taiwanese Journal of Mathematics 13 (2009), 1063–1076.S. Bu and J. Kim, Operator-valued Fourier multipliers on periodic Triebel spaces, Acta Mathematica Sinica 21 (2005), 1049–1056.G. Cai and S. Bu, Well-posedness of second order degenerate integro-differential equations with infinite delay in vector-valued function spaces, Mathematische Nachrichten 289 (2016), 436–451.R. Chill and S. Srivastava, Lp-maximal regularity for second order Cauchy problems, Mathematische Zeitschrift 251 (2005), 751–781.R. Denk, M. Hieber and J. Prüss, R-boundedness, Fourier multipliers and problems of elliptic and parabolic type, Memoirs of the American Mathematical Society 166 (2003).O. Diekmann, S. A. van Giles, S. M. Verduyn Lunel and H.-O. Walther, Delay Equations, Applied Mathematical Sciences, Vol. 110, Springer, New York, 1995.K. J. Engel and R. Nagel, One-Parameter Semigroups for Linear Evolution Equations, Graduate Texts in Mathematics, Vol. 194, Springer, New York, 2000.M. Fabrizio, A. Favini and G. Marinoschi, An optimal control problem for a singular system of solid liquid phase-transition, Numerical Functional Analysis and Optimization 31 (2010), 989–1022.A. Favini and G. Marinoschi, Periodic behavior for a degenerate fast diffusion equation, Journal of Mathematical Analysis and Applications 351 (2009), 509–521.A. Favini and G. Marinoschi, Identification of the time derivative coefficients in a fast diffusion degenerate equation, Journal of Optimization Theory and Applications 145 (2010), 249–269.A. Favini and A. Yagi, Degenerate differential equations in Banach spaces, Monographs and Textbooks in Pure and Applied Mathematics, Vol. 215, Marcel Dekker, New York, 1999.X. L. Fu and M. Li, Maximal regularity of second-order evolution equations with infinite delay in Banach spaces, Studia Mathematica 224 (2014), 199–219.G. C. Gorain, Boundary stabilization of nonlinear vibrations of a flexible structure in a bounded domain in Rn, Journal of Mathematical Analysis and Applications 319 (2006), 635–650.P. Grisvard, Équations différentielles abstraites, Annales Scientifiques de l’école Normale Superieure 2 (1969), 311–395.J. K. Hale and W. Huang, Global geometry of the stable regions for two delay differential equations, Journal of Mathematical Analysis and Applications 178 (1993), 344–362.Y. Hino, S. Murakami and T. Naito, Functional Differential Equations with Infinite Delay, Lecture Notes in Mathematics, Vol. 1473, Springer, Berlin, 1991.B. Kaltenbacher, I. Lasiecka and M. Pospieszalska, Well-posedness and exponential decay of the energy in the nonlinear Moore-Gibson-Thomson equation arising in high intensity ultrasound, Mathematical Models & Methods in Applied Sciences 22 (2012), 1250035.V. Keyantuo and C. Lizama, Fourier multipliers and integro-differential equations in Banach spaces, Journal of the London Mathematical Society 69 (2004), 737–750.V. Keyantuo and C. Lizama, Maximal regularity for a class of integro-differential equations with infinite delay in Banach spaces, Studia Mathematica 168 (2005), 25–50.V. Keyantuo, C. Lizama and V. Poblete, Periodic solutions of integro-differential euations in vector-valued function spaces, Journal of Differential Equations 246 (2009), 1007–1037.C. Lizama, Fourier multipliers and periodic solutions of delay equations in Banach spaces, Journal of Mathematical Analysis and Applications 324 (2006), 921–933.C. Lizama and V. Poblete, Maximal regularity of delay equations in Banach spaces, Studia Mathematica 175 (2006), 91–102.C. Lizama and R. Ponce, Periodic solutions of degenerate differential equations in vector valued function spaces, Studia Mathematica 202 (2011), 49–63.C. Lizama and R. Ponce, Maximal regularity for degenerate differential equations with infinite delay in periodic vector-valued function spaces, Proceedings of the Edinburgh Mathematical Society 56 (2013), 853–871.R. Marchand, T. Mcdevitt and R. Triggiani, An abstract semigroup approach to the third-order Moore–Gibson–Thompson partial differential equation arising in highintensity ultrasound: structural decomposition, spectral analysis, exponential stability, Mathematical Methods in the Applied Sciences 35 (2012), 1896–1929.V. Poblete, Solutions of second-order integro-differential equations on periodic Besov spaces, Proceedings of the Edinburgh Mathematical Society 50 (2007), 477–492.V. Poblete and J. C. Pozo, Periodic solutions of an abstract third-order differential equation, Studia Mathematica 215 (2013), 195–219.J. Prüss, Evolutionary Integral Equations and Applications, Monographs in Mathematics, Vol. 87, Birkhäuser, Heidelberg, 1993.G. A. Sviridyuk and V. E. Fedorov, Linear Sobolev type Equations and Degenerate Semigroups of Operators, Inverse and Ill-posed Problems Series, VSP, Utrecht, 2003.L. Weis, Operator-valued Fourier multiplier theorems and maximal Lp-regularity, Mathematische Annalen 319 (2001), 735–758