Biomedical subjects

M E Kowalski

Publications and source records attributed to M E Kowalski.

4 recordsLinked to original sources

PubMed2003

A temperature-based feedback control system for electromagnetic phased-array hyperthermia: theory and simulation.

A hybrid proportional-integral-in-time and cost-minimizing-in-space feedback control system for electromagnetic, deep regional hyperthermia is proposed. The unique features of this controller are that (1) it uses temperature, not specific absorption rate, as the criterion for selecting the relative phases and amplitudes with which to drive the electromagnetic phased-array used for hyperthermia and (2) it requires on-line computations that are all deterministic in duration. The former feature, in addition to optimizing the treatment directly on the basis of a clinically relevant quantity, also allows the controller to sense and react to time- and temperature-dependent changes in local blood perfusion rates and other factors that can significantly impact the temperature distribution quality of the delivered treatment. The latter feature makes it feasible to implement the scheme on-line in a real-time feedback control loop. This is in sharp contrast to other temperature optimization techniques proposed in the literature that generally involve an iterative approximation that cannot be guaranteed to terminate in a fixed amount of computational time. An example of its application is presented to illustrate the properties and demonstrate the capability of the controller to sense and compensate for local, time-dependent changes in blood perfusion rates.

Body Temperature↗

PubMed2000

Computation of the signal-to-noise ratio of high-frequency magnetic resonance imagers.

A method of computing the signal-to-noise ratio (SNR) in high-frequency magnetic resonance (MR) imaging systems is presented. The method uses a numerical solution to Maxwell's equations which can capture all relevant electrodynamic effects at high B0-field strengths. Using this method, the intrinsic SNR of both volume and surface coils loaded with the human head is calculated as a function of frequency. It is shown that although the available SNR from any point scales favorably with frequency, phase inhomogeneity over the volume of the head may pose a challenge to achieving improved SNR with traditional imaging techniques at high B0-field strengths.

Biomedical Engineering↗

PubMed1994

[Pneumonia complicated by bacteremia with Stomatococcus mucilaginosus].

A rare strain of Stomatococcus mucilaginosus (formerly Micrococcus) was isolated from blood of a patient after pneumonia, which was causing an enlargement of lymph nodes and groin fistula. Chemical composition of cell wall of this microorganism (analysis of amino acids and diagnostically important sugars), elementary composition of lipids (fatty acids, phospholipids and glycolipids) and molar percentage of guanine and cytosine (%GC), were determined. Results completely agreeable with results published elsewhere were obtained which resulted in reclassification of this species (Kocur (1982, Int. J.Sys.Bacterial. 32, 374-377)). This case indicates that some relative pathogens require modern diagnostic methods and when not recognized in cases of acquired or directed immunosuppression can create a serious threat.

Bacteremia↗

PubMed1989

[Clinical and electrocardiographic aspects of mitral valve prolapse].

Group sex and age, symptoms, ST segment, T wave, QT interval and PR interval abnormalities on the EKG, as whereas cardiac arrhythmias were analysed in two groups of patients from the cardiology outpatient clinics: patients from group I (n = 63) had and echocardiographic diagnosis of mitral valve prolapse (MVP), whereas patients from group II (n = 63) had a normal echocardiogram. Women exceeded men in number in both groups, and the female/male ratio was 2.5:1 and 1.5:1 in groups I and II, respectively. The age range in group I was 54 years (15-69) with a mean of 29.3 +/- 10.8 years, whereas group II had an age range of 49 years (9-58) and a mean of 26.5 +/- 10.1 years. Palpitations, atypical precordial pain and dyspnea were the most frequent presenting symptoms in both groups, all been present in 52 (88.2%) of the patients from group I and in 45 (71.5%) from group II. ST and T abnormalities occurred in 2 (4%) patients from group I and in 8 (13%) from group II. The PR interval was equal to or shorter than 0.20s in all cases. The corrected QT interval (Q-Tc) was prolonged in 2 (4%) patients from group I and in 1 (1.5%) from group II. The tachyarrhythmias as a whole, when analysed through the conventional 12-lead EKG, were found in 17 (31.5%) of the group I patients and in 10 (16.5%) of the patients from group II. Ventricular premature depolarizations were detected in 12 (22%) patients from group I and in 8 (13.5%) from group II (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗