On the analysis of the double Hopf bifurcation in machining processes via centre manifold reduction.

The single-degree-of-freedom model of orthogonal cutting is investigated to study machine tool vibrations in the vicinity of a double Hopf bifurcation point. Centre manifold reduction and normal form calculations are performed to investigate the long-term dynamics of the cutting process. The normal form of the four-dimensional centre subsystem is derived analytically, and the possible topologies in the infinite-dimensional phase space of the system are revealed. It is shown that bistable parameter regions exist where unstable periodic and, in certain cases, unstable quasi-periodic motions coexist with the equilibrium. Taking into account the non-smoothness caused by loss of contact between the tool and the workpiece, the boundary of the bistable region is also derived analytically. The results are verified by numerical continuation. The possibility of (transient) chaotic motions in the global non-smooth dynamics is shown.

[Biologic detection methods in the comparison of circulating tumor cells and micrometastases]. / A keringö daganatsejtek és a mikrometasztázisok kimutatása molekuláris biológiai módszerekkel.

Early studies could not prove any diagnostic or prognostic value of the presence of tumor cells in the circulation. Recent knowledge in the field of molecular and cellular pathology provided better understanding of mechanisms of metastasis formation therefore advanced detection of circulating cancer cells has been suggested as a supplementary method of staging metastatic cancer. Beside the widely used immunocytochemical methods the reverse transcriptase-polymerase chain reaction (RT-PCR) is now the most relevant technique in studying micrometastases of solid tumors. Magnetic activated cell sorting (MACS) is a recently developed method for the enrichment of different cells from suspensions by magnetic labelling of their surface antigens. RT-PCR seems to be the most sensitive to detect circulating cancer cells or micrometastases, but it is possible by MACS to purify cells for further immunological, biochemical or genetic analysis. The aim of this review is to give a brief summary of recently used methods and to discuss the clinical relevance of the attainable results.

[Medical use of artificial neural networks]. / A mesterséges neurális hálózatok orvosi alkalmazásai.

The main aim of the research in medical diagnostics is to develop more exact, cost-effective and handsome systems, procedures and methods for supporting the clinicians. In their paper the authors introduce a new method that recently came into the focus referred to as artificial neural networks. Based on the literature of the past 5-6 years they give a brief review--highlighting the most important ones--showing the idea behind neural networks, what they are used for in the medical field. The definition, structure and operation of neural networks are discussed. In the application part they collect examples in order to give an insight in the neural network application research. It is emphasised that in the near future basically new diagnostic equipment can be developed based on this new technology in the field of ECG, EEG and macroscopic and microscopic image analysis systems.