THE TECHNOLOGY OF PUNCTIONAL CRYOABLATION OF MALIGNANT BREAST TUMORS

The cryoablation of malignant breast tumors technology with the use of modern miniinvasive equipment based on liquid nitrogen is represented. Navigation method, monitoring and postoperative observation of patients are presented in detail. In clinical cases, where surgical operation alternatives can be considered, indications to cryoablation are: elderly patients and slow growth of tumor; enough distance from the skin; precise ultrasound visualization of tumor borders; limited lesion size, which allow icy front to fully cover the tumor; specialized oncological center conditions; navigational and miniinvasive cryogenic equipment availability; additional special training for oncologists; careful psychological training for patients and their relatives; informed consent formalization by patient and her refusal of standard treatment. Procedure starts with trepan-biopsy to get the material for immunohistochemical investigations. The first probe is installed paratumorally in the deepest point and its cryofixation in tissues is performed without large glaciation zone formed. After that other probes and injectional microthermocouples are installed in tumor's outline, then cooling is started. Capture of healthy tissues must be 1 sm with exposition retention during 10 minutes and passive warming during 10-15 minutes. Second cooling is obligatorily in the same probes' position and in the same time-intervals. All the common rules of diagnostics and complex treatment are preserved. The clinical case of successful cryoablation is presented.

CENTER CONDITIONS FOR A CUBIC DIFFERENTIAL SYSTEM HAVING AN INTEGRATING FACTOR

We find conditions for a singular point O(0, 0) of a center or a focus type to be a center, in a cubic differential system with one irreducible invariant cubic. The presence of a center at O(0, 0) is proved by constructing integrating factors.

Center Conditions for a Class of Rigid Quintic Systems

The problem of determining necessary and sufficient conditions on P and Q for system. x = - y+P(x+y),y = x+Q(x+y) to have a center at the origin is known as the Poincaré center-focus problem. So far, people has tried many ways to solve the problem of central focus. However, it is difficult to solve the center focus problem of higher order polynomial system. In this paper, we use the Poincaré and Alwash-Lloyd methods to study the center focus problem and derive the center conditions of the five periodic differential equation.

Center Conditions and Bifurcation of Limit Cycles Created from a Class of Second-Order ODEs

In this paper, a class of second-order ODEs is investigated. First of all, a method of computing singular point values is established for this kind of systems. Then, two classes of second-order ODEs are studied to illustrate the efficiency of the method, and the center conditions and bifurcation of limit cycles are obtained. Above all, center conditions of a class of non-polynomial systems are classified by using this method.