Composite modeling of transfer functions

The problem under consideration is how to estimate the frequency function of a system and the associated estimation error when a set of possible model structures is given and then one of them is known to contain the true system. The “classical” solution to this problem is to, first, use a consistent model structure selection criterion to discard all but one single structure, second, estimate a model in this structure and, third, conditioned on the assumption that the chosen structure contains the true system, compute an estimate of the estimation error. For a finite data set, however, one cannot guarantee that the correct structure is chosen, and this “structural” uncertainty is lost in the previously mentioned approach. In this contribution a method is developed that combines the frequency function estimates and the estimation errors from all possible structures into a joint estimate and estimation error. Hence, this approach bypasses the structure selection problem. This is accomplished by employing a Bayesian setting. Special attention is given to the choice of priors. With this approach it is possible to benefit from a priori information about the frequency function even though the model structure is unknown     

Simultaneous measurements of thermal conductivity and thermal diffusivity of insulators,fluids and conductors using the transient plane source (TPS) technique

Simultaneous measurements of thermal conductivity and thermal diffusivity of composite red-sand bricks, glycerine and mercury have been made at room temperature by the recently developed transient plane source (TPS) technique. This paper describes, in brief, the theory and the experimental conditions for the simultaneous measurements of thermal conductivity and thermal diffusivity of insulators, fluids and metals. The source of heat is a hot disc made out of bifilar spirals. The disc also serves as a sensor of temperature increase in the sample. The measured values of the thermal conductivity and thermal diffusivity of these samples are in agreement with the values reported earlier using other methods. The advantage of the TPS technique is the simplicity of the equipment, simultaneous information on thermal conductivity and thermal diffusivity, and also the applicability of the technique to insulators, fluids and metals.     

Transient plane source (TPS) technique for measuring thermal transport properties of building materials

The electrical circuit for the recently developed transient plane source (TPS) technique for fast and precise measurements of thermal transport properties of solids has been modified for more convenient and more automated measurements. The technique has been tested for measurements of thermal conductivity and thermal diffusivity for a series of building materials ranging from thermally insulating materials (extruded polystyrene and PMMA) to good thermal conductors (stainless steel and aluminium). The results obtained in this work agree well with other techniques and international standard materials. This agreement indicates that the TPS method is accurate to within ±5% over a thermal conductivity range of four orders of magnitude (0.02 W m^?1 K^?1 to 200 W m^?1 k^?1).     

Dynamic vectorcardiography for early diagnosis of acute myocardial infarction compared with 12-lead electrocardiogram. BIOMACS Study Group

BACKGROUND: The aim of the study was to assess the diagnostic accuracy of multilead continuous vectorcardiography (VCG) for early diagnosis of acute myocardial infarction (AMI) in patients admitted to hospital because of suspicion of AMI. VCG was compared with resting 12-lead electrocardiogram (ECG) on admission. METHODS: In a multicentre study, 107 patients with chest pain (< or = 12 h) were included. The diagnosis of AMI was on the basis of World Health Organization criteria. Continuous VCG was recorded for 12-24 h and the data were evaluated blindly at 2 and 6 h of recording and after the completion of recording (12-24 h). RESULTS: AMI was diagnosed in 74 patients. The VCG recording had a diagnostic accuracy of 71% after 2 h and 86% after both the 6 h and the completed VCG recording. Compared with ECG on admission, the VCG recording after 6 h showed a significantly greater sensitivity: 86% compared with 62% (P < 0.01). In patients with non-diagnostic ECG on arrival (n = 55), VCG after 6 h had a diagnostic accuracy of 85%, a sensitivity of 82% and a specificity of 89%. CONCLUSIONS: VCG might be useful for early diagnosis of AMI, especially in patients with non-diagnostic ECG.     

Evaluation of a surfactant mixture C31G as a teat dip by a modified excised teat model

A mixture of amphoteric surfactants with antimicrobial properties, C31G, was evaluated as a teat dip by a modified excised teat model. The model was modified to avoid misinterpretation of results from indigenous bacterial microflora on teats. In three experiments, bacterial numbers recovered from teats dipped in .75, 1.5, and 3.0% solutions of C31G were compared with bacteria recovered from undipped teats (negative controls) and teats dipped with 1.0% iodophor (an effective teat dip). Mean log reductions of teat end concentrations of Staphylococcus, aureus, Streptococcus fecalis, and Escherichia coli were determined in each experiment. Efficacy was greatest for the 3.0% solution of C31G with mean log reductions (Log reduction = Log 10 of controls - Log 10 of dipped teats) 3.53 for Staphylococcus aureus, 2.89 for Streptococcus fecalis, and 3.16 for Escherichia coli. Iodophor (1%) yielded mean log reductions of 3.26 for Staphylococcus aureus, 2.16 for Streptococcus fecalis, and 2.83 for Escherichia coli. For all three organisms, number of viable organisms decreased with increasing concentrations of C31G. The efficacy of C31G should be evaluated in vivo.     

Ligand-dependent recruitment of the Arnt coregulator determines DNA recognition by the dioxin receptor

The intracellular basic region/helix-loop-helix (bHLH) dioxin receptor mediates signal transduction by dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) and functions as a ligand-activated DNA binding protein directly interacting with target genes by binding to dioxin response elements. Here we show that the partially purified, ligand-bound receptor alone could not bind target DNA. In contrast, DNA binding by the receptor could be induced by addition of a cytosolic auxiliary activity which functionally and biochemically corresponded to the bHLH factor Arnt. While Arnt exhibited no detectable affinity for the dioxin response element in the absence of the dioxin receptor, it strongly promoted the DNA binding function of the ligand-activated but not the ligand-free receptor forms. Arnt also functionally reconstituted in vitro the DNA binding activity of a mutant, nuclear translocation-deficient dioxin receptor phenotype in cytosolic extracts from a dioxin-resistant hepatoma cell line. Importantly, coimmunoprecipitation experiments showed that Arnt physically interacted in solution with the ligand-activated dioxin receptor but failed to heterodimerize with the ligand-free, hsp90-associated receptor form. Mutational analysis suggested that the functional interaction between these two factors occurred via the bHLH motif of Arnt. These data suggest that dioxin receptor activity is governed by a complex pattern of combinatorial regulation involving repression by hsp90 and then by ligand-dependent recruitment of the positive coregulator Arnt. The dioxin receptor system also provides the first example of signal-controlled dimerization of bHLH factors.     

Acute poisoning with dextropropoxyphene. Clinical symptoms and plasma concentrations

Twenty-four undergraduate male volunteers participated in an experimental designed to assess the effect of voluntary control of heart rate deceleration on skin conductance level. One group of subjects received heart rate feedback training and a second group performed a tracking task. Because heart-rate feedback was presented via a visual display, the tracking task group was included to control for display monitoring influences on heart rate. Results demonstrated feedback mediated acquisition of learned control of heart rate slowing. More importantly, the heart-rate slowing performance was accompanied by increases in skin conductance level. This 'fractionation' of physiological responding suggests the presence of a physiological response pattern which may counter initial attempts to produce greater magnitude slowing effects.