Mixed problems for the telegraph equation in the case of a system consisting of two segments with different densities and elasticities but equal impedances

Mixed problems for the telegraph equatio

Mixed problems for the telegraph equation in the case of a system consisting of two segments with different densities and elasticities but equal impedances: One-sided control

✍ I. N. Smirnov 📂 Article 📅 2010 🏛 SP MAIK Nauka/Interperiodica 🌐 English ⚖ 162 KB

Mixed problems describing longitudinal o

Mixed problems describing longitudinal oscillations of a rod consisting of two segments with different densities and different elasticities but equal impedances

✍ V. A. Il’in; P. V. Luferenko 📂 Article 📅 2009 🏛 SP MAIK Nauka/Interperiodica 🌐 English ⚖ 161 KB

Saliva and serum samples were collected

Saliva and serum samples were collected from eight healthy volunteers every two hours during a 26-hour period. Melatonin concentrations were measured by radioimmunoassay after chloroform extraction using radioiodinated melatonin as a tracer. Five of the subjects had high serum melatonin levels at night (peak levels higher than 75 pg/ml); in three subjects the highest serum melatonin concentration was 20-40 pg/ml. All subjects had low levels (P <0.001, was obtained for all detectable value pairs (n= 73). The regression and correlation coefficients were almost equal for the peak values of melatonin and during the rising and descending phases of the secretion patterns. However, no significant correlation was found between low daytime salivary and serum concentrations when calculated separately. In the five high-secretors the melatonin levels in saliva reflected reliably the changes in serum, but in the three low-secretors the correlation between salivary and serum melatonin was not significant. The proportion of melatonin found in saliva decreased with increasing serum melatonin levels. Circadian rhythm parameters were estimated by single cosinor analysis. The acrophases did not differ significantly within a subject in the concomitant measurements of serum and salivary melatonin. The measurements of salivary melatonin levels seem valid for studies on melatonin rhythms, but the melatonin concentrations measured in saliva do not always consistently reflect the absolute concentrations in blood.

✍ Maija-Liisa Laakso; Tarja Porkka-Heiskanen; Aino Alila; Dag Stenberg; Gunnar Joh 📂 Article 📅 1990 🏛 John Wiley and Sons 🌐 English ⚖ 622 KB