Stabilizing chaotic vortex trajectories: an example of high-dimensional control

A chaos control algorithm is developed to actively stabilize unstable periodic orbits of higher-dimensional systems. The method assumes knowledge of the model equations and a small number of experimentally accessible parameters. General conditions for controllability are discussed. The algorithm is applied to the Hamiltonian problem of point vortices inside a circular cylinder with applications to an experimental plasma system.Comment: 15 LaTex pages, 4 Postscript figures adde

Chaotic advection of reacting substances: Plankton dynamics on a meandering jet

We study the spatial patterns formed by interacting populations or reacting chemicals under the influence of chaotic flows. In particular, we have considered a three-component model of plankton dynamics advected by a meandering jet. We report general results, stressing the existence of a smooth-filamental transition in the concentration patterns depending on the relative strength of the stirring by the chaotic flow and the relaxation properties of planktonic dynamical system. Patterns obtained in open and closed flows are compared.Comment: 5 pages, 3 figues, latex compiled with modegs.cl

The surgical technique and the age of the horse both influence the outcome of mosaicplasty in a cadaver equine stifle model

Six pieces of grafts, 6.5 mm in diameter, 20 mm in length, were taken from each of 170 cadaver hindlimbs, using the cranial surface of the medial femoral trochlea for harvesting. The age of the horses varied between 4 months and 23 years. 30 limbs under the age of 12 years were selected for transplantation. Three of six grafts were transplanted into the medial femoral condyle using different combinations of tunnel depth and dilation. With ageing, a significant decline in transplantability was detected. In general, mosaicplasty cannot be recommended in horses above 11 years. Based on a previous clinical case (Bodo et al., 2000), a good surface alignment was indeed achieved with a combination of graft length drilling and dilation in most cases. However, the occasional entrapment of cartilage debris under the graft prevented perfect alignment in the present cadaver study in 27% of the grafts transplanted in this manner. Since the protrusion of grafts never exceeded 1.5 mm, we conclude that drilling 3–5 mm deeper than graft length with graft length deep dilation can avoid disadvantageous protrusion of the transplanted hyaline cartilage caps, achieving bone decompression at the same time

Smooth-filamental transition of active tracer fields stirred by chaotic advection

The spatial distribution of interacting chemical fields is investigated in the non-diffusive limit. The evolution of fluid parcels is described by independent dynamical systems driven by chaotic advection. The distribution can be filamental or smooth depending on the relative strength of the dispersion due to chaotic advection and the stability of the chemical dynamics. We give the condition for the smooth-filamental transition and relate the H\"older exponent of the filamental structure to the Lyapunov exponents. Theoretical findings are illustrated by numerical experiments.Comment: 4 pages, 3 figure

Determinants of biological drug survival in rheumatoid arthritis:Evidence from a Hungarian rheumatology center over 8 years of retrospective data

OBJECTIVE: To compare drug survival of biological therapies in patients with rheumatoid arthritis (RA), and analyze the determinants of discontinuation probabilities and switches to other biological therapies. MATERIALS AND METHODS: Consecutive RA patients initiating first biological treatment in one rheumatology center between 2006 and 2013 were included. Log-rank test was used to analyze the differences between the survival curves of different biological drugs. Cox regression was applied to analyze the discontinuation due to inefficacy, the occurrence of adverse events, or to any reasons. RESULTS: A total of 540 patients were included in the analysis. The most frequently used first-line biological treatments were infliximab (N=176, 33%), adalimumab (N=150, 28%), and etanercept (N=132, 24%). Discontinuation of first tumor necrosis factor-alpha (TNF-α) treatment was observed for 347 (64%) patients, due to inefficacy (n=209, 60%), adverse events (n=103, 30%), and other reasons (n=35, 10%). Drug survival rates for TNF-α and non-TNF-α therapies were significantly different, and were in favor of non-TNF-α therapies. Every additional number of treatment significantly increased the risk of inefficacy by 27% (p<0.001) and of adverse events by 35% (p=0.002). After the discontinuation of the initial TNF-α treatment, switching to rituximab and tocilizumab was associated with significantly longer treatment duration than switching to a second TNF-α. The non-TNF-α therapies resulted in significantly longer treatment duration, due to both less adverse events and longer maintenance of effectiveness. CONCLUSION: Non-TNF-α therapies resulted in significantly longer treatment duration, and lost their effectiveness later. Increase in the number of switches significantly increased the risk of discontinuation of any biological therapy

Development of Population Tariffs for the CarerQol Instrument for Hungary, Poland and Slovenia

__Background:__ The CarerQol instrument can be used in economic evaluations to measure the care-related quality of life of informal caregivers. Tariff sets are available for Australia, Germany, Sweden, the Netherlands, the UK, and the USA. __Objective:__ Our objective was to develop tariff sets for the CarerQol instrument for Hungary, Poland and Slovenia and to compare these with the existing value sets. __Methods:__ Discrete-choice experiments were carried out in Hungary, Poland and Slovenia. Data were collected through an online survey between November 2018 and January 2019, using representative samples of 1000 respondents per country. Tariffs were calculated from coefficient estimates from panel mixed multinomial logit models with random parameters. __Results:__ All seven CarerQol domains contributed significantly to the utility associated with different caregiving situations. Attributes valued highest were ‘physical health