1,012 research outputs found

    Connectedness properties of the set where the iterates of an entire function are unbounded

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    We investigate the connectedness properties of the set I+(f) of points where the iterates of an entire function f are unbounded. In particular, we show that I+(f) is connected whenever iterates of the minimum modulus of f tend to ∞. For a general transcendental entire function f, we show that I+(f)∪ \{\infty\} is always connected and that, if I+(f) is disconnected, then it has uncountably many components, infinitely many of which are unbounded

    On multiply connected wandering domains of meromorphic functions

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    We describe conditions under which a multiply connected wandering domain of a transcendental meromorphic function with a finite number of poles must be a Baker wandering domain, and we discuss the possible eventual connectivity of Fatou components of transcendental meromorphic functions. We also show that if ff is meromorphic, UU is a bounded component of F(f)F(f) and VV is the component of F(f)F(f) such that f(U)Vf(U)\subset V, then ff maps each component of U\partial U onto a component of the boundary of VV in \hat{\C}. We give examples which show that our results are sharp; for example, we prove that a multiply connected wandering domain can map to a simply connected wandering domain, and vice versa.Comment: 18 pages. To be published in the Journal of the London Mathematical Societ

    Functions of small growth with no unbounded Fatou components

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    We prove a form of the cosπρ\cos \pi \rho theorem which gives strong estimates for the minimum modulus of a transcendental entire function of order zero. We also prove a generalisation of a result of Hinkkanen that gives a sufficient condition for a transcendental entire function to have no unbounded Fatou components. These two results enable us to show that there is a large class of entire functions of order zero which have no unbounded Fatou components. On the other hand we give examples which show that there are in fact functions of order zero which not only fail to satisfy Hinkkanen's condition but also fail to satisfy our more general condition. We also give a new regularity condition that is sufficient to ensure that a transcendental entire function of order less than 1/2 has no unbounded Fatou components. Finally, we observe that all the conditions given here which guarantee that a transcendental entire function has no unbounded Fatou components, also guarantee that the escaping set is connected, thus answering a question of Eremenko for such functions

    Singularities of meromorphic functions with Baker domains

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    Computerized CBT (Think, Feel, Do) for depression and anxiety in children and adolescents: outcomes and feedback from a pilot randomized controlled trial

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    Background: Research has demonstrated the effectiveness of computerized cognitive behaviour therapy (cCBT) for depression and anxiety in adults, but there has been little work with children and adolescents. Aims: To describe the development of a cCBT intervention (Think, Feel, Do) for young people, and preliminary outcomes and feedback from a pilot randomized controlled trial. Method: Twenty participants aged 11 to 16 with depression or anxiety were randomized to receive cCBT immediately or after a delay. Standardized measures were used to assess self-reported anxiety, depression, self-esteem and cognitions, as well as parent rated strengths and difficulties. A feedback form was also completed to assess young people's views of the programme. Results: A total of 15 participants completed the pre and post assessments in the trial, and 17 provided feedback on the intervention. Paired samples t-tests demonstrated significant improvements on 3 subscales in the control condition, compared to 7 subscales in the cCBT condition. Feedback showed moderate to high satisfaction for participants. Conclusions: This study provides encouraging preliminary results for the effectiveness and acceptability of cCBT with this age group.</jats:p
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