Can we distinguish between tree-ring eccentricity developed as a result of landsliding and prevailing winds? Consequences for dendrochronological dating

The aim of our study was to compare patterns of tree-ring eccentricity developed in Nor-way spruce trees as a result of landsliding with the one caused by the prevailing wind (in 2 study sites), and with the normal growth of trees (in 2 reference sites). We sampled 20 trees per study site and 10 per reference site. Two cores were taken from each tree (120 cores in total) from the upslope and downslope, windward and leeward sides of stems. Ring widths measured on opposite sides of stems were compared using the method of percent eccentricity index. Graphs of the index obtained for individual trees were analysed. Statistical indicators were calculated for a percent eccentricity in-dex. Disturbance events were dated and the response index was calculated. The results show that the patterns of eccentricity developed as a result of the prevailing winds and due to landsliding differ from one another and from the reference sites. The results suggest that the impact of the prevailing wind on tree growth is more severe than the impact of landsliding. The difference may result from the slow-moving character of the landslide under study. The results, however, indicate that wind impact should be taken into account in dendrogeomorphic research and that the impact of mass movements should be considered in dendroecological studies on wind

901–37 Computer Implementation of Wavelet Decomposition of Signal Averaged Electrocardiograms

Simple spectral analysis of signal averaged electrocardiograms (SAECG) has been the subject of numerous studies. However, the approaches reported so far appear inferior to the gold-standard time-domain analysis of SAECG. At the same time, the limitations of the time-domain analysis are well known and suggest that a more complex spectral analysis of SAECG will be of clinical importance. One of the possibilities for a more complex spectral analysis of SAECG is the so called Wavelet Analysis (WA) which is a time-scale technique suitable for the detection of small transient signals even if they are hidden in large waves. It is obtained by expanding the signal on a set of functions resulting from translation (time) and dilatation (scale) of a socalled “analysing wavelet”. WA provides a bidimensional representation of the signal in function of time and scale.In order to apply WA to SAECG, a special software package written in Borland Pascal has been developed. The WA of the signal s(t) is computed according to the formula Sg(a,b)=∫-∞+∞(1/√a)g(t)s(t)dt, where parameter a corresponds to the dilatation and parameter b to the time shift. The package uses the Morlet wavelet g(t)=exp(iωt) exp(-t2/2) for ω>=5.3. Empirically, 54 scales were chosen, defined by the scale parameter a=40×2-m, with m ranging from 0.95 to 3.6 with an increment of 0.05. The middle frequencies of the corresponding wavelets range from 250 to 40Hz. The package processes SAECG files in the standard ART format. To synthesise the information contained within all three wavelet transforms, a wavelet vector magnitude is obtained from the wavelets of three averaged X, Y, Z leads and computed as WM=(WX2+WY2+WZ2)1/2.The package has been employed in several studies which showed that (a) WA of SAECG is highly reproducible and (b) selected parameters of WA are superior to the time-domain analysis of SAECG when used for identification of survivors of acute myocardial infarction who are at high risk of sudden death and/or ventricular tachycardia. This comparison of WA and time domain analysis of SAECG used receiver operator and positive predictive characteristics which showed highly significant differences

801-4 Prognostic Implications of QT and QU Interval Measures in Acute Myocardial Infarction

Prolongation of the QT interval corrected using Bazett's formula (QTc) has been reported as a marker for increased risk of arrhythmic events after acute myocardial infarction (AMI). However, the QU interval changes have not been examined. At the same time, QU interval may be of clinical significance, especially in the light of recent experimental evidence linking the U wave with the subpopulation of the so-called M cells within myocardial wall. To evaluate prognostic significance of QT and QU interval measures in AMI, we studied 512 survivors of acute phase of their first myocardial infarction. Patients with conduction defects and drugs likely to affect QT measures were noT included into the analysis. The following intervals were estimated in all the measurable leads on a standard predischarge 12-lead ECG (25 mm/sec paper speed) using a digitizing pad—mean RR, mean and max QT, and mean QU. All QT and QU intervals were subsequently corrected for heart rate using Bazett's formula. At one year follow-up, 23 patients (Group I. 19 male. mean age 58.7±8.9 years) suffered arrhythmic events (VT/VF or sudden cardiac death). This subset of patients was compared with arrhythmia-free group of 489 subjects (Group II, 385 male, mean age 56.1±9.2 years). Statistical analysis was performed using unpaired t-test and ANOVA, results are expressed as mean±SD.GroupQT meanQTc meanQT maxQTc maxQU meanQUc meanI358.7±31.5426.6±30.7396.5±38.5472.8±40.3459.5±58.7535.2±41.3II387.3±44.1423.9±24421.7±51.5467.9±79.1552.0±73.9585.7±55.1p<0.002NS0.02NS0.0010.01The significant difference in QU and QUc, but not in QT intervals persisted even after elimination of the effect of heart rate (ANOVA: p<0.007 and 0.011, respectively).ConclusionThe differences in the QT but not QU interval measures in the 2 groups can be explained by differing heart rates. Shorter QU interval seemed to identify patients at risk of arrhythmic events after AMI. The pathophysiological basis for this finding is not clear, but could be related to differences in the subpopulation of M cells within myocardial wall

Dendrochronological dating as the basis for developing a landslide hazard map – An example from the Western Carpathians, Poland

Most landslide hazard maps are developed on the basis of an area’s susceptibility to a land-slide occurrence, but dendrochronological techniques allows one to develop maps based on past land-slide activity. The aim of the study was to use dendrochronological techniques to develop a landslide hazard map for a large area, covering 3.75 km2. We collected cores from 131 trees growing on 46 sampling sites, measured tree-ring width, and dated growth eccentricity events (which occur when tree rings of different widths are formed on opposite sides of a trunk), recording the landslide events which had occurred over the previous several dozen years. Then, the number of landslide events per decade was calculated at every sampling site. We interpolated the values obtained, added layers with houses and roads, and developed a landslide hazard map. The map highlights areas which are poten-tially safe for existing buildings, roads and future development. The main advantage of a landslide hazard map developed on the basis of dendrochronological data is the possibility of acquiring long se-ries of data on landslide activity over large areas at a relatively low cost. The main disadvantage is that the results obtained relate to the measurement of anatomical changes and the macroscopic charac-teristics of the ring structure occurring in the wood of tilted trees, and these factors merely provide in-direct information about the time of the landslide event occurrence

Conditioned variation in heart rate during static breath-holds in the bottlenose dolphin (Tursiops truncatus)

Funding for this project was provided by the Office of Naval Research to AF (ONR Award # N00014-16-1-3088).Previous reports suggested the existence of direct somatic motor control over heart rate (fH) responses during diving in some marine mammals, as the result of a cognitive and/or learning process rather than being a reflexive response. This would be beneficial for O2 storage management, but would also allow ventilation-perfusion matching for selective gas exchange, where O2 and CO2 can be exchanged with minimal exchange of N2. Such a mechanism explains how air breathing marine vertebrates avoid diving related gas bubble formation during repeated dives, and how stress could interrupt this mechanism and cause excessive N2 exchange. To investigate the conditioned response, we measured the fH-response before and during static breath-holds in three bottlenose dolphins (Tursiops truncatus) when shown a visual symbol to perform either a long (LONG) or short (SHORT) breath-hold, or during a spontaneous breath-hold without a symbol (NS). The average fH (ifHstart), and the rate of change in fH (difH/dt) during the first 20 s of the breath-hold differed between breath-hold types. In addition, the minimum instantaneous fH (ifHmin), and the average instantaneous fH during the last 10 s (ifHend) also differed between breath-hold types. The difH/dt was greater, and the ifHstart, ifHmin, and ifHend were lower during a LONG as compared with either a SHORT, or an NS breath-hold (P < 0.05). Even though the NS breath-hold dives were longer in duration as compared with SHORT breath-hold dives, the difH/dt was greater and the ifHstart, ifHmin, and ifHend were lower during the latter (P < 0.05). In addition, when the dolphin determined the breath-hold duration (NS), the fH was more variable within and between individuals and trials, suggesting a conditioned capacity to adjust the fH-response. These results suggest that dolphins have the capacity to selectively alter the fH-response during diving and provide evidence for significant cardiovascular plasticity in dolphins.Publisher PDFPeer reviewe

Assessment of landslide hazard from tree-ring eccentricity and from compression wood - a comparison

We have compared maps of landslide activity and hazard, developed with the use of two different dendrochronological indicators: tree-ring eccentricity and reaction (compression) wood. The maps were prepared based on 125 Norway spruce (Picea abies L. Karst.) trees growing at 44 sampling points, distributed over an area of 3.75 km2. In general, the two maps show similar patterns of landslide activity. However, tree-ring eccentricity yielded a greater number of dated events (246) compared to compression wood (129). Besides the differences in the absolute values of dating results, the general landslide activity and hazard zonation based on both disturbances are similar. Both growth disturbances develop as a result of stem tilting. Eccentricity develops after slight tilting, while compression wood is developed when tilting is more significant. Because of the differences in the strength of disturbing factors, which cause the development of compression wood and growth eccentricity, the best approach would be to combine the results of dating obtained from the two methods. The dendrochronological analysis of tree growth disturbances (eccentric growth and compression wood) is a promising approach for determining landslide hazards in forested mountain areas and can be applied in spatial management