Investigation of intracranial media ultrasonic monitoring model

The objectives are to investigate the peculiarities of the ultrasound pulse propagation through human extra/intracranial media by mathematical simulation and to confirm the simulation results experimentally by proving the suitability of the ultrasonic time-of-flight measurement method for human intracranial media (IM) physiological non-invasive monitoring. The mathematical model of ultrasound pulse propagation through the human extra/intracranial media is described. The simulation of various physiological phenomena were performed to determine the relationship between the characteristics of the transmitted ultrasound pulse through the human head and the acoustic properties of the IM. It is shown that non-invasive monitoring of the IM acoustic properties is possible by measuring the changes of the ultrasonic signal time-of-flight and the oscillation period. The influence made by variations in acoustic parameters of the external tissue/skull bones on the non-invasive measurement data is investigated and methods of compensation of that influence are presented. The models were applied for developing of a new non-invasive sonographic intracranial pressure (ICP) monitor (Vittamed). Comparative studies of this monitor with the invasive ICP monitor (Camino) have shown the possibility of achieving clinically acceptable accuracy of the long term non-invasive ICP monitoring of head injured patients in intensive care units.     

Limit distributions of sums of random variables defined on a finite homogeneous Markov chain. II

Vilnius University, Naugarduko 24, 2600 Vilnius, Lithuania. Translated from Lietuvos Matematikos Rinkinys, Vol. 34, No. 1, pp. 94–106, January–March, 1994.     

Limit distributions of sums of random variables defined on a finite homogeneous Markov chain. I

Vilnius University, Naugarduko str. 24, 2006 Vilnius, Lithuania. Translated from Lietuvos Matematikos Rinkinys, Vol. 33, No. 4, pp. 424–434, October–December, 1993.     

XPS and ionic conductivity studies on Li1.3Al0.15Y0.15Ti1.7(PO4)3 ceramics

Li_1.3Al_0.15Y_0.15Ti_1.7(PO₄)₃ compound was synthesized by solid-state reaction, and ceramics were sintered. The surfaces of the ceramics were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. Li_1.3Al_0.15Y_0.15Ti_1.7(PO₄)₃ samples were tested in solid galvanic cells Ag|O₂+CO₂|Li₂CO₃|Li_1.3Al_0.15Y_0.15Ti_1.7(PO₄)₃|LiMnO₂+Mn₂O₃|O₂|Ag. The electromotive force measurements of this cell indicated that investigated samples are practically pure Li-ion conductors. Impedance spectroscopy studies have been performed in the frequency range 10^?2–3·10⁹ Hz and temperatures from ?57 °C to 334 °C. Three dispersion regions related to Li⁺ ionic transport in bulk, grain boundaries of the ceramics and to polarization of electrodes have been found. Total conductivity changes according to Arrhenius law in the studied temperature range, but an anomalous behavior was observed for the bulk conductivity of the ceramics.     

Quantification of the evolution of shape storage and recovery in thermally responsive shape memory polymers

This study demonstrates the relevance of strain and stress storage/recovery profiles for the thermomechanical behaviour of thermally responsive Shape Memory Polymers (SMPs). It is shown how these experimentally determined profiles may be used for the development, calibration and validation of continuum-based models describing the shape memory effect in polymeric materials. The presented methodology applies both to small and finite strain deformation problems under the assumption of constant strain and cooling/heating rates. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Non-parametric estimation from simultaneous renewal–failure–degradation data with competing risks

A joint model for linear degradation and competing failure data with partial renewals is proposed. Non-parametric estimation procedures for failure intensities and failure probabilities as functions of degradation level are given. Asymptotic properties of the estimators are investigated. To cite this article: V. Bagdonavi?ius et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Untersuchung der Latices der Styrol/Carboxylat-Copolymerisate

Ohne Zusammenfassung     

Non-parametric estimation from simultaneous degradation and failure time dataEstimation non-paramétrique à partir de données de dégradation et de défaillances

The paper considers degradation and failure time models with multiple failure modes. Dependence of traumatic failure intensities on the degradation level are included into the models. Non-parametric estimators of various reliability characteristics are proposed. Theorems on simultaneous asymptotic distribution of random functions characterizing degradation and intensities of traumatic events are proposed. To cite this article: V. Bagdonavi?ius et al., C. R. Acad. Sci. Paris, Ser. I 335 (2002) 183–188.     

Structural and electrical investigation of (Ag3AsS3)x(As2S3)1?x superionic glasses

Structural studies of (Ag₃AsS₃) _x (As₂S₃)_1−x chalcogenide superionic glasses in the compositional range x = 0.3–0.9 were performed by scanning electron microscopy. Temperature and compositional dependences of transmission coefficient, electrical conductivity, and activation energy were investigated