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2021 ◽  
Vol 12 ◽  
Author(s):  
Vera Békés ◽  
Katie Aafjes-van Doorn ◽  
Xiaochen Luo ◽  
Tracy A. Prout ◽  
Leon Hoffman

Therapists’ forced transition to provide psychotherapy remotely during the COVID-19 pandemic offers a unique opportunity to examine therapists’ views and challenges with online therapy. This study aimed to investigate the main challenges experienced by therapists during the transition from in-person to online therapy at the beginning of the pandemic and 3 months later, and the association between these challenges and therapists’ perception of the quality of the relationship with their online patients, and therapists’ attitudes and views about online therapy and its efficacy at these two timepoints. As part of a large-scale international longitudinal survey, we collected data from 1,257 therapists at two timepoints: at the start of COVID-19, when many therapists switched from providing in-person therapy to online therapy, as well as 3 months later, when they had had the opportunity to adjust to the online therapy format. At both timepoints, therapists reported on perceived challenges, quality of working alliance and real relationship, attitudes toward online therapy, and their views on online therapy’s efficacy compared to in-person therapy. Factor analysis of individual survey items at both timepoints identified four different types of challenges among this therapist sample: Emotional connection (feeling connected with patients, reading emotions, express or feel empathy), Distraction during sessions (therapist or patient), Patients’ privacy (private space, confidentiality), and Therapists’ boundaries (professional space, boundary setting). Older and more experienced therapists perceived fewer challenges in their online sessions. At baseline, all four types of challenges were associated with lower perceived quality of the therapeutic relationship (working alliance and real relationship), and more negative attitudes toward online therapy and its efficacy. After 3 months, perceived challenges with three domains – Emotional connection, Patients’ privacy, and Therapists’ boundaries significantly decreased – whereas challenges in the fourth domain – Distraction – increased. In our study, therapists’ concerns about being able to connect with patients online appeared to be the most impactful, in that it predicted negative attitudes toward online therapy and its perceived efficacy 3 months later, above and beyond the effect of therapists’ age and clinical experience. Clinical and training implications are discussed.


Author(s):  
Dmitrii A. Pozharskii

Results are reviewed collected in the investigations of periodic contact and mixed problems of the plane, axially symmetric and spatial elasticity theory. Among mixed problems, cut (crack) problems are focused integral equations of which are connected with those for contact problems. The periodic contact problems stimulate research of the discrete contact of rough (wavy) surfaces. Together with classical elastic domains (half-plane, half-space, plane and full space), we consider periodic problems for cylinder, layer, cone and spatial wedge. Most publications including fun-damental ones by Westergaard and Shtaerman deals with plane periodic problems of the elasticity theory. Here, one can mention approaches based on complex variable functions, Fourier series, Green’s functions and potential func-tions. A fracture mechanics approach to the plane periodic contact problem was developed. Methods and approaches are considered which allow us to take friction forces, adhesion and wear into account in the periodic contact. For spatial periodic and doubly periodic contact and properly mixed problems, we describe such methods as the localiza-tion method, the asymptotic methods, the method of nonlinear boundary integral equations, the fast Fourier trans-form. The half-space is the simplest model for elastic solids. But for the simplest straight-line periodic punch system, some three-dimensional contact problems (normal contact or tangential contact for shifted cohesive coatings) turn out to be incorrect because their integral equations contain divergent series. Considering three-dimensional periodic problems, I.G. Goryacheva disposes circular punches in special way (circular orbits, polar coordinated are used for centers of the punches), in this case one can prove convergence of the series in the integral equation (it is important that the punches are circular). For the periodic problems for an elastic layer, V.M. Aleksandrov has shown that the series in integral equations converge but the kernels become more complicated. In the present paper, we demonstrate that for the straight-line periodic punch system of arbitrary form the contact problem for a half-space turns out to be correct in case of more complicated boundary conditions. Namely, it can be sliding support or rigid fixation of a half-plane on the half-space boundary, the half-plane boundary should be parallel to the straight-line (the punch system axis) for arbitrary finite distance between the parallel lines. On this way, for sliding support, the kernel of the period-ic problem integral equation kernel is free of integrals, it consists of single convergent series (normal contact, the kernel is given in two equivalent forms). We consider classical percolation (how neighboring contact domains pene-trate one to another, investigated by K.L. Johnson, V.A. Yastrebov with co-authors) for the three-dimensional periodic contact amplification as well as percolation for the straight-line punch system. A similar approach is suggested for the case of periodic tangential contact (coatings system cohesive with a half-space boundary shifted along its axis or perpendicular to it). Here, one can separate out unique solutions of auxiliary problems because the line of changing boundary conditions on the half-space boundary can provoke non-uniqueness. The method proposed opens possibility to consider more complicated three-dimensional periodic contact problems for straight-line punch systems with changing boundary conditions inside the period.


2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Peter J. Catto ◽  
Elizabeth A. Tolman

The velocity dependent resonant interaction of particles with applied radiofrequency (rf) waves during heating and current drive in the presence of pitch angle scattering collisions gives rise to narrow collisional velocity space boundary layers that dramatically enhance the role of collisions as recently shown by Catto (J. Plasma Phys., vol. 86, 2020, 815860302). The behaviour is a generalization of the narrow collisional boundary layer that forms during Landau damping as found by Johnston (Phys. Fluids, vol. 14, 1971, pp. 2719–2726) and Auerbach (Phys. Fluids, vol. 20, 1977, pp. 1836–1844). For a wave of parallel wave number ${k_{||}}$ interacting with weakly collisional plasma species of collision frequency $\nu$ and thermal speed ${v_{\textrm{th}}}$ , the effective collision frequency becomes of order $\nu {({k_{||}}{v_{th}}/\nu )^{2/3}} \gg \nu $ . The narrow boundary layers that arise because of the diffusive nature of the collisions allow a physically meaningful wave–particle interaction time to be defined that is the inverse of this effective collision frequency. The collisionality implied by the narrow boundary layer results in changes in the standard quasilinear treatment of applied rf fields in tokamaks while remaining consistent with causality. These changes occur because successive poloidal interactions with the rf are correlated in tokamak geometry and because the resonant velocity space dependent interactions are controlled by the spatial and temporal behaviour of the perturbed full wave fields rather than just the spatially local Landau and Doppler shifted cyclotron wave–particle resonance condition associated with unperturbed motion of the particles. The correlation of successive poloidal circuits of the tokamak leads to the appearance in the quasilinear operator of transit averaged resonance conditions localized in velocity space boundary layers that maintain negative definite entropy production.


Author(s):  
Xavier Claeys ◽  
Lorenzo Giacomel ◽  
Ralf Hiptmair ◽  
Carolina Urzúa-Torres

AbstractA complex screen is an arrangement of panels that may not be even locally orientable because of junction lines. A comprehensive trace space framework for first-kind variational boundary integral equations on complex screens has been established in Claeys and Hiptmair (Integr Equ Oper Theory 77:167–197, 2013. https://doi.org/10.1007/s00020-013-2085-x) for the Helmholtz equation, and in Claeys and Hiptmair (Integr Equ Oper Theory 84:33–68, 2016. https://doi.org/10.1007/s00020-015-2242-5) for Maxwell’s equations in frequency domain. The gist is a quotient space perspective that allows to make sense of jumps of traces as factor spaces of multi-trace spaces modulo single-trace spaces without relying on orientation. This paves the way for formulating first-kind boundary integral equations in weak form posed on energy trace spaces. In this article we extend that idea to the Galerkin boundary element (BE) discretization of first-kind boundary integral equations. Instead of trying to approximate jumps directly, the new quotient space boundary element method employs a Galerkin BE approach in multi-trace boundary element spaces. This spawns discrete boundary integral equations with large null spaces comprised of single-trace functions. Yet, since the right-hand-sides of the linear systems of equations are consistent, Krylov subspace iterative solvers like GMRES are not affected by the presence of a kernel and still converge to a solution. This is strikingly confirmed by numerical tests.


Author(s):  
Anel Ferreira-Snyman

The current space arena has changed significantly since the 1950s, when outer space activities commenced. At the time of the adoption of the Outer Space Treaty (and the related General Assembly Resolutions), the outer space arena was largely dominated by the political interests of the two major space powers, the USA and the (then) USSR. Although states have remained the primary actors in regulating the use of outer space, the extent to which private companies would become involved in the exploration and use of space was not envisaged at the time of the conclusion of the space treaties. It is particularly the involvement of private space actors that complicates the traditional understanding of the prohibition on territorial sovereignty in outer space. With specific reference to the outer space boundary, the principle of the common heritage of humankind and property rights in outer space, this contribution aims to highlight some of the challenges to the prohibition of sovereignty in view of current developments in the arena of outer space. This analysis suggests that the blanket prohibition on sovereignty in outer space should be re-evaluated in order to keep up with the fast developing technological advancements in space exploration, and that clear legal rules be developed to provide legal certainty for all role players.


2020 ◽  
pp. 62-74
Author(s):  
Cut Novisar Syahfitri

This study aims to determine and describing the implementation of the development of Coastal Green Open Space and the factors that cause the ineffective implementation of the policy. This research focused on policy implementation of spatial plans in development of urban areas which based by theory of Charles O. Jones: organizations, interpretation, and application. The author using descriptive qualitative research method with an inductive approach. The data were collected through observation, interviews, and documentation. While the data were analyzed with data analysis, data presentation, and conclusion. The research data were analyzed using data analysis techniques, data presentation, and drawing conclusion. The results showed that the implementation process of the regional spatial planning policy in the development of green open space on the coastline of Cirebon City was not implemented properly. The main factor that causes the ineffective implementation of the policy is that the interpretation of the policy it self is vary, so that it affects the implementation of the policy. Suggested to the Cirebon City Government needs to support and be committed to implementing a coastal border green open space development policy and the Cirebon City Government needs to be prepared to face every possibility and challenge of problems that arise and become obstacles in the implementation of the development policy of coastal green open space.Keywords: Implementation, Open Green Space Boundary Beach


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