• Statistical model for enhanced radiocarbon dating of human bone collagen samples by introducing improved collagen correction in archaeology
• Influence and compensation of heart rate variability on identification of local ischemic lesion

Result 1: Statistical model for enhanced radiocarbon dating of human bone collagen samples by introducing improved collagen correction in archaeology

Projects: VEGA 2/4026/04 a 2/7087/27 in cooperation with Dendrochronological Laboratory, Bratislava

Investigators: P. Barta, S. Štolc Jr.

Statistical model for HBCO (Human Bone Collagen Offset) correction was designed, which leads to the clarification of dating human bones in archeology. HBCO correction is of the utmost importance to the archaeologist, who cares more about the date of death than the moment of individuals completion of puberty. Pitfall of the original HBCO correction, as defined by M. Geyh and P. Barta, was the need to know the exact age of individual at death. However, in archeology, this is generally not known. The age of the individual is determined on the basis of anthropological expertise through approximate ages, usually with a precision of decades. In our research, we proposed a statistical model that allows HBCO correction to be applied also in the case of approximate anthropological estimates (Fig. 1a). We also propose ways to implement this improved correction in the existing software for the calibration of radiocarbon data (OxCal, BCal, Caliba). Due to the complex shape of the calibration curve the effect of the same HBCO correction may differ radically for various radiocarbon data. So we applied this method to he real archaeological example in which we demonstrate this phenomenon (Fig. 1b).

Figure 1: a) HBCO correction function proposed by M. Geyhom (thick black line). There are two phases of collagen development: (i) youth (0-19 years), and (ii) aging (20 years and over). The horizontal axis depicts the statistical models of anthropological categories, the vertical axis displays the distribution of relevant HBCO corrections. b) The impact of different sample HBCO corrections to real archaeological data. HD-11774 (grave 1 / 1, Weinstadt-Endersbach) and HD-11794 (grave 1 / 1, Gäufelden-Tailfingen) real radiocarbon data from the earlier Bronze Age and the calibrated probability distribution expressing allowable calendar date. Extensions A1-B and S1-B represent different HBCO correction applied to the relevant date.

Publications:

• BARTA, P. - ŠTOLC, Svorad: HBCO correction: its impact on archaeological absolute dating. Radiocarbon 49 (2), 2007, 465-472.
• BARTA, P. - ŠTOLC, Svorad: HBCO correction: its impact on archaeological absolute dating. In: 19th International 14C Conference. Oxford, Great Britain, April 3-7, 2006.

Result 2: Influence and compensation of heart rate variability on identification of local ischemic lesion

Projects: APVV-51-059005, VEGA 2/7092/27

Investigators: M. Turzová, E. Hebláková, J. Švehlíková, M. Tyšler

Local iIschemic lesion in the myocardium can be represented by a dipole and its parameters can be computed from the difference between integrals of ECG potentials (over the QT interval - from the beginning to the end of the ventrcular activation) measured during ischemia manifestation and without it. If there is some change of heart rate (HR) between these measurements, the length of QT interval is also changed and causes errors in computed dipole parameters. OT interval changes of 10% or 20% simulated in a computer model caused changes of dipole position up to 12 or 21 mm and change of its direction up to 14° or 36°, respectively. It means that the HR changes should be compensated. However, QT length measurement is difficult and may also be influenced by the ischemia. That's why we proposed to use instead of the measured QT length its estimate computed from the HR change using the formula according Fridericia. Testing of this approach in 5 patients showed that differences between measured and estimated QT lengths did not exceed 5% and this difference caused changes of dipole position less than 12 mm and changes of its direction less than 18°. These results show acceptable agreement between measured and estimated QT lengths and support the possibility to use this kind of HR compensation during noninvasive identification of local ischemic lesion.

Publications:

• HEBLÁKOVÁ E., TYŠLER M., TURZOVÁ M., ŠVEHLÍKOVÁ J., SZAKOLCZAI K., HARASZTI K., FILIPOVÁ S.: Noninvasive detection of repolarization changes in the heart. Anadolu kardiyoloji dergisi (Anatolian Journal of Cardiology), Vol. 7, Suppl. 1, 2007, 130-132, ISSN 1302-8723.
• TYŠLER M., HEBLÁKOVÁ E., ŠVEHLÍKOVÁ J., TURZOVÁ M.: Experimental Results of Noninvasive Identification of Local Ischemia Using Dipole Models and HR ECG Mapping. Invited paper on the 94th ICB Seminar on High resolution ECG and MCG mapping. (Proceedings are in preparation.)