On Different Models for Generating Random SAT Problems

In the last decade a lot of effort has been invested into both theoretical and experimental analysis of sat phase transition. However, a deep theoretical understanding of this phenomenon is still lacking. Besides, many of experimental results are based on some assumptions that are not supported theoretically. In this paper we introduce the notion of sat--equivalence and we prove that some restrictions often used in sat experiments don't make an impact on location of a crossover point. We consider several fixed and random clause length sat models and relation between them. We also discuss one new sat model and report on a detected phase transition for it

Correlations of Free Thyroid Hormones Measured by Tandem Mass Spectrometry and Immunoassay with Thyroid-Stimulating Hormone across 4 Patient Populations

BACKGROUND: Accurate measurement of free thyroid hormones is important for managing thyroid disorders. Ultrafiltration liquid chromatography tandem mass spectrometry (LC-MS/MS) can reliably measure the concentrations of small molecules, including thyroid hormones. Our study was designed to compare free thyroid hormone measurements performed with immunoassay and LC-MS/MS. METHODS: We studied the performance of LC-MS/MS in 4 different populations comprising pediatric patients, euthyroid adults, and healthy nonpregnant and pregnant women. The samples obtained from each population numbered 38, 200, 28, and 128, respectively. Free thyroxine, free triiodothyronine, and thyroid-stimulating hormone (TSH) concentrations were documented. RESULTS: LC-MS/MS measurement of free thyroid hormones provided better correlation with log-transformed serum TSH in each population and also the populations combined. The correlations between free thyroxine measured by LC-MS/MS and log TSH in the pediatric outpatients and healthy adults were −0.90 and −0.77, respectively. The correlations for immunoassay were −0.82 and −0.48. The correlations between free triiodothyronine measured by LC-MS/MS and TSH for both pediatric and healthy adult populations were −0.72 and −0.68, respectively. CONCLUSIONS: Free thyroid hormone concentrations measured by LC-MS/MS correlate to a greater degree with log TSH values compared to concentrations measured by immunoassay. This correlation was maintained across the patient populations we studied and may reflect the accuracy and specificity of LC-MS/MS. The superior ability of LC-MS/MS to enable documentation of the well-known thyroid hormone–TSH relationship supports the use of this measurement technique in a variety of clinical situations