Janusz Wójcik and Tomasz Grodzki
Janusz Wójcik and Tomasz Grodzki
Janusz Wójcik, Tomasz Grodzki and Krzysztof Kaseja
Minimally Invasive Subtotal Esophagectomy
In the study a subtotal videothoracoscopic and laparoscopic esophageal resection with cervical anastomosis was presented with discussion concerning the new surgical problems and positions (classical and prone) of videothoracoscopic and laparoscopic approaches. The technique of esophageal elevation during mediastinal preparation, ligation and dissection of the azygos vein, pharmacological elongation of the graft using Glucagon as well as tips regarding easier identification of the esophagus at the outlet level was described. The usefulness of the harmonic scalpel and endostaplers was stressed. Additionally, findings and outcomes were discussed.
Roch Plewik, Piotr Synowiec and Janusz Wójcik
Two-phase CFD simulation of the monodyspersed suspension hydraulic behaviour in the tank apparatus from a circulatory pipe
The hydrodynamics in fluidized-bed crystallizers is studied by CFD method. The simulations were performed by a commercial packet of computational fluid dynamics Fluent 6.x. For the one-phase modelling (15), a standard k-ε model was applied. In the case of the two-phase flows the Eulerian multi-phase model with a standard k-ε method, aided by the k-ε dispersed model for viscosity, has been used respectively. The collected data put a new light on the suspension flow behaviour in the annular zone of the fluidised bed crystallizer. From the presented here CFD simulations, it clearly issues that the real hydraulic conditions in the fluidised bed crystallizers are far from the ideal ones.
Janusz Wójcik, Jerzy Litniewski and Andrzej Nowicki
A trabecular bone consists of trabeculae whose mechanical properties differ significantly from the surrounding marrow, therefore an ultrasonic wave propagating within the bone structure is strongly scattered. The aim of this paper was to evaluate the contribution of the first, second and higher order scattering (multiple scattering) into the total scattering of ultrasound in a trabecular bone. The scattering due to the interconnections between thick trabeculae, usually neglected in trabecular bone models, has been also studied. The basic element in our model of the trabecular bone was an elastic cylinder with a various finite-length and diameter as well as orientation. The applied model was taking into account variation of both, elements size and their spatial configuration. The field scattered on the bone model was evaluated by solving numerically the integral form of the generalized Sturm-Liouville equation describing a scalar wave in inhomogeneous and lossy media. For the scattered fields calculated numerically the effective cross-sections were determined. The influence of absorption on the scattering coefficients was demonstrated. The results allowed to conclude that within the frequency range from 0.5 to 1.5 MHz contribution of the second order scattering to the effective backscattering cross-section is at least 500 times lower than that due to the first order scattering. It was noticed that for a frequency higher than 1.5 MHz fast growth of the backscattering (reflection) coefficients, calculated for the second order scattering, occurs.
Jolanta Bijańska, Krzysztof Wodarski and Janusz Wójcik
Efficient and effective preparation the production of new products is important requirement for a functioning and development of small and medium-sized enterprises. One of the methods, which support the fulfilment of this condition is project management. This publication presents the results of considerations, which are aimed at developing a project management model of preparation the production of a new product, adopted to specificity of small and medium-sized enterprises.
Wojciech Secomski, Andrzej Nowicki, Janusz Wójcik, Marcin Lewandowski, Mateusz Walczak and Ryszard Tymkiewicz
The use of therapeutic ultrasound continues to grow. A focused ultrasonic wave can increase the tissue temperature locally for the non-invasive cancer treatment or other medical applications. The authors have designed a seven-element annular array transducer operating at 2.4 MHz. Each element was excited by sine burst supplied by a linear amplifier and FPGA control circuits. The acoustic field, generated by a transducer was initially numerically simulated in a computer and next compared to water tank hydrophone measurements performed at 20, 40 and 60 mm focal depth. The results showed good agreement of the measurements with theory and the possibility to focus the ultrasound in the preselected area. The total acoustic power radiated by the annular array was equal to 2.4 W.
Robert Olszewski, Zbigniew Trawiński, Janusz Wójcik and Andrzej Nowicki
The main objective of this study is to develop an echocardiographic model of the left ventricular and numerical modeling of the speckles- markers tracking in the ultrasound (ultrasonographic) imaging of the left ventricle. The work is aimed at the creation of controlled and mobile environment that enables to examine the relationships between left ventricular wall deformations and visualizations of these states in the form of echocardiographic imaging and relations between the dynamically changing distributions of tissue markers of studied structures.
Andrzej Nowicki, Marcin Lewandowski, Janusz Wójcik, Ryszard Tymkiewicz, Rasmus Lou-Moller, Wanda Wolny and Tomasz Zawada
Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and non-linear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature - 11 mm, 12 mm, 15 mm, 16 mm.
All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The transducers were excited with Golay coded sequences at 35-40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4-1.5 and finally resulting in a SNR gain of the same order.
Lidia Karwacka, Aneta Kamińska, Dorota Wójcik, Anna Szabelska, Justyna Batkowska, Janusz Borowicz and Leszek Szalewski
Introduction. The fashion for a tan appeared at the beginning of the twentieth century, in the era of technological progress and urbanization with medical knowledge about heliotherapy and the promotion of the tan by fashion designer Coco Chanel being a contributing factor in it. The International Agency for Research on Cancer classified the UV to the first group of carcinogens but despite these warnings the increase in exposure to UV radiation has been seen in recent years. New solariums have been created around the world so that people can enjoy a tan all year round, no matter what the weather conditions are.
Aim. The aim of the study was to assess the attitudes and behaviors related to UV radiation exposure among residents of Łęczna.
Material and methods. A survey conducted among 180 people inquiring about sociodemographic characteristics and attitudes and behaviours associated with exposure to UV radiation while tanning.
Results. Statistical analysis of the data obtained in the study showed that the socio-demographic characteristics affect the attitudes and behaviour associated with exposure to UV radiation. Suntan is believed to be significantly more fashionable among women, people with secondary education who have no permanent relationships.
Conclusion. There is a need for preventive actions and educational programs concerning the dangers of UV radiation in order to develop not only knowledge but also the correct behaviour in society.