Temporal and dimensional effects in evolutionary graph theory

The spread in time of a mutation through a population is studied analytically and computationally in fully-connected networks and on spatial lattices. The time, t_*, for a favourable mutation to dominate scales with population size N as N^{(D+1)/D} in D-dimensional hypercubic lattices and as N ln N in fully-connected graphs. It is shown that the surface of the interface between mutants and non-mutants is crucial in predicting the dynamics of the system. Network topology has a significant effect on the equilibrium fitness of a simple population model incorporating multiple mutations and sexual reproduction. Includes supplementary information.Comment: 6 pages, 4 figures Replaced after final round of peer revie

Fully adaptive multiresolution schemes for strongly degenerate parabolic equations with discontinuous flux

A fully adaptive finite volume multiresolution scheme for one-dimensional strongly degenerate parabolic equations with discontinuous flux is presented. The numerical scheme is based on a finite volume discretization using the Engquist--Osher approximation for the flux and explicit time--stepping. An adaptivemultiresolution scheme with cell averages is then used to speed up CPU time and meet memory requirements. A particular feature of our scheme is the storage of the multiresolution representation of the solution in a dynamic graded tree, for the sake of data compression and to facilitate navigation. Applications to traffic flow with driver reaction and a clarifier--thickener model illustrate the efficiency of this method

‘Image‘ Kota Goettingen Dan Sekitarnya Sebagai Salah Satu Tujuan Wisata Alam Dan Rekreasi Luar Ruangan (Study Kasus Menurut Mahasiswa Internasional Di Universitas Goettingen)

Nature tourism/outdoor recreation is one the fastest growing tourism activities in the world. More and more people travel to natural sites due to increased environmental awareness and a high degree of urbanization.The objective of this research was to capture the image of Göttingen and its surrounding area, using a combination of structured and unstructured methods as recommended by previous researchers. The image determination was considered important for positioning and differentiating the destination from other competitors. From a marketing point of view, image determination could increase tourist interest to visit the destination, travel satisfaction, and intention to return. The structured method used image attributes, which were evaluated using a 5-point Likert scale while the unstructured method used three open-ended questions. In addition, the research was also done to identify the nature of outdoor recreation/nature tourism among International students. The study focused on International students, which have certain characteristics that are different from those of domestic students. Data was taken from January to April 2014. 326 respondents delivered useable responses/data. This research revealed that a combination of structured and unstructured methods was able to capture the underlying image dimension of Göttingenand its surroundings. Considering the high propensity for travelling and previous travel experience of the students, it could be interpreted that International students at Göttingen University are one of the prospective nature tourism markets. Therefore, customized marketing strategy could be applied to attract them

Aversive tension in female adolescents with Anorexia Nervosa : a controlled ecological momentary assessment using smartphones

BACKGROUND: Current models of Anorexia Nervosa (AN) emphasize the role of emotion regulation. Aversive tension, described as a state of intense arousal and negative valence, is considered to be a link between emotional events and disordered eating. Recent research focused only on adult patients, and mainly general emotion regulation traits were studied. However, the momentary occurrence of aversive tension, particularly in adolescents with AN, has not been previously studied. METHOD: 20 female adolescents with AN in outpatient treatment and 20 healthy adolescents aged 12 to 19years participated in an ecological momentary assessment using their smartphones. Current states of aversive tension and events were assessed hourly for two consecutive weekdays. Mean and maximum values of aversive tension were compared. Multilevel analyses were computed to test the influence of time and reported events on aversive tension. The effect of reported events on subsequent changes of aversive tension in patients with AN were additionally tested in a multilevel model. RESULTS: AN patients showed higher mean and maximum levels of aversive tension. In a multilevel model, reported food intake was associated with higher levels of aversive tension in the AN group, whereas reported school or sport-related events were not linked to specific states of aversive tension. After food intake, subsequent increases of aversive tension were diminished and decreases of aversive tension were induced in adolescents with AN. CONCLUSIONS: Aversive tension may play a substantial role in the psychopathology of AN, particular in relation with food intake. Therefore, treatment should consider aversive tension as a possible intervening variable during refeeding. Our findings encourage further research on aversive tension and its link to disordered eating. TRIAL REGISTRATION: German register of clinical trials (DRKS): DRKS00005228 (Date of registration: September 2, 2013)

Meeting report of the 2nd German dialectical behavior therapy for adolescents network meeting

Over the past 30 years, dialectical behavior therapy has been shown to be an effective treatment for adult borderline personality disorder. The adaptation of DBT for adolescents (DBT-A) in different patient groups has also led to some promising improvements of the respective psychopathology. During the second German DBT-A network meeting in 2015 in Mainz, Germany, a need for further research and innovative approaches in treatment of adolescents became apparent and resulted in controversial discussions. Main issues were enlarging evidence of effectiveness of DBT-A strategies with regard to family interaction, i.e. involving caregivers in treatment. In general, there seems to be a dire need for disentangling different therapeutic strategies and resulting treatment outcomes, especially concerning the needs of different patient groups. Additionally, the implementation of smartphone-based real life assessment and intervention into DBT-A was discussed extensively. Providing time congruent skills within an application, decreasing aversive tension and reducing dysfunctional behavior could lead to an enhanced therapist-patient interaction. This meeting report presents the core issues raised during the network meeting and discusses their implications for further research

A multilayer shallow water system for polydisperse sedimentation

This work considers the flow of a fluid containing one disperse substance consisting of small particles that belong to different species differing in size and density. The flow is modelled by combining a multilayer shallow water approach with a polydisperse sedimentation process. This technique allows one to keep information on the vertical distribution of the solid particles in the mixture, and thereby to model the segregation of the particle species from each other, and from the fluid, taking place in the vertical direction of the gravity body force only. This polydisperse sedimentation process is described by the well-known Masliyah-Lockett-Bassoon (MLB) velocity functions. The resulting multilayer sedimentation-ow model can be written as a hyperbolic system with nonconservative products. The definitions of the nonconservative products are related to the hydrostatic pressure and to the mass and momentum hydrodynamic transfer terms between the layers. For the numerical discretization a strategy of two steps is proposed, where the first one is also divided into two parts. In the _rst step, instead of approximating the complete model, we approximate a reduced model with a smaller number of unknowns. Then, taking advantage of the fact that the concentrations are passive scalars in the system, we approximate the concentrations of the different species by an upwind scheme related to the numerical flux of the total concentration. In the second step, the effect of the transference terms defined in terms of the MLB model is introduced. These transfer terms are approximated by using a numerical ux function used to discretize the 1D vertical polydisperse model (see Bürger, García, Karlsen and Towers, J. Eng. Math. 60 (2008), 387{425). Finally, some numerical examples are presented. Numerical results suggest that the multilayer shallow water model could be adequate in situations where the settling takes place from a suspension that undergoes horizontal movement

Convergence of finite volume scheme for degenerate parabolic problem with zero flux boundary condition

This note is devoted to the study of the finite volume methods used in the discretization of degenerate parabolic-hyperbolic equation with zero-flux boundary condition. The notion of an entropy-process solution, successfully used for the Dirichlet problem, is insufficient to obtain a uniqueness and convergence result because of a lack of regularity of solutions on the boundary. We infer the uniqueness of an entropy-process solution using the tool of the nonlinear semigroup theory by passing to the new abstract notion of integral-process solution. Then, we prove that numerical solution converges to the unique entropy solution as the mesh size tends to 0

Complex population dynamics as a competition between multiple time-scale phenomena

The role of the selection pressure and mutation amplitude on the behavior of a single-species population evolving on a two-dimensional lattice, in a periodically changing environment, is studied both analytically and numerically. The mean-field level of description allows to highlight the delicate interplay between the different time-scale processes in the resulting complex dynamics of the system. We clarify the influence of the amplitude and period of the environmental changes on the critical value of the selection pressure corresponding to a phase-transition "extinct-alive" of the population. However, the intrinsic stochasticity and the dynamically-built in correlations among the individuals, as well as the role of the mutation-induced variety in population's evolution are not appropriately accounted for. A more refined level of description, which is an individual-based one, has to be considered. The inherent fluctuations do not destroy the phase transition "extinct-alive", and the mutation amplitude is strongly influencing the value of the critical selection pressure. The phase diagram in the plane of the population's parameters -- selection and mutation is discussed as a function of the environmental variation characteristics. The differences between a smooth variation of the environment and an abrupt, catastrophic change are also addressesd.Comment: 15 pages, 12 figures. Accepted for publication in Phys. Rev.

Survival-extinction phase transition in a bit-string population with mutation

A bit-string model for the evolution of a population of haploid organisms, subject to competition, reproduction with mutation and selection is studied, using mean field theory and Monte Carlo simulations. We show that, depending on environmental flexibility and genetic variability, the model exhibits a phase transtion between extinction and survival. The mean-field theory describes the infinite-size limit, while simulations are used to study quasi-stationary properties.Comment: 11 pages, 5 figure

Dynamics of Competitive Evolution on a Smooth Landscape

We study competitive DNA sequence evolution directed by {\it in vitro} protein binding. The steady-state dynamics of this process is well described by a shape-preserving pulse which decelerates and eventually reaches equilibrium. We explain this dynamical behavior within a continuum mean-field framework. Analytical results obtained on the motion of the pulse agree with simulations. Furthermore, finite population correction to the mean-field results are found to be insignificant.Comment: 4 pages, 2 figures, revised, to appear in Phys. Rev. Let