Comparing knowledge with belief can go wrong in two dimensions: If the authors employ a wider notion of knowledge, then they do not compare like with like because they assume a narrow notion of belief. If they employ only a narrow notion of knowledge, then their claim is not supported by the evidence. Finally, we sketch a superior teleological view.

Dielectric profiling (DEP), a capacitive method for measuring an ice core’s electrical conductivity and permittivity, has been in use for several years. We have built an improved DEP instrument with a modified guarded-electrode geometry whose capacitance can be determined from potential theory. The new instrument can measure an ice core’s conductivity and permittivity to within a few per cent error, a high enough accuracy to infer its density using well-known models.

Measuring cortisol in hair is a promising method to assess long-term alterations of the biological stress response system, and hair cortisol concentrations (HCC) may be altered in psychiatric disorders and in subjects suffering from chronic stress. However, the pattern of associations between HCC, chronic stress and mental health require clarification. Our exploratory study: (1) assessed the association between HCC and perceived stress, symptoms of depression and neuroticism, and the trait extraversion (as a control variable); and (2) made use of the twin design to estimate the genetic and environmental covariance between the variables of interest. Hair samples from 109 (74 female) subjects (age range 12–21 years, mean 15.1) including 8 monozygotic (MZ) and 21 dizygotic (DZ) twin pairs were analyzed. Perceived stress was measured with the Perceived Stress Scale and/or the Daily Life and Stressors Scale, neuroticism, and extraversion with the NEO-Five Factor Inventory or the Junior Eysenck Personality Questionnaire, and depressive symptoms with the Somatic and Psychological Health Report. We found a modest positive association between HCC and the three risk factors — perceived stress, symptoms of depression, and neuroticism (r = 0.22–0.33) — but no correlation with extraversion (-0.06). A median split revealed that the associations between HCC and risk factors were stronger (0.47–0.60) in those subjects with HCC >11.36 pg/mg. Furthermore, our results suggest that the genetic effects underlying HCC are largely shared with those that influence perceived stress, depressive symptoms, and neuroticism. These results of our proof of principle study warrant replication in a bigger sample but raise the interesting question of the direction of causation between these variables.

Inconsistent results exist from human and animal studies for Se and methionine (Met) regarding their influence on homocysteine (HCys) and cholesterol (Chol) metabolism. To elucidate these contradictions, sixty-four weanling albino rats were divided into eight groups of 8, and were fed diets containing four different Se levels (15, 50, 150 and 450 μg/kg) either in combination with the recommended Met level of 3 g/kg (C15, C50, C150 and C450) or with an increased Met concentration of 15 g/kg (M15, M50, M150 and M450) for 8 weeks. Plasma HCys was twofold higher in the Se-supplemented C groups than in group C15. Met addition also doubled plasma HCys compared with the respective C groups. In contrast, the expression of the key enzymes of glutathione biosynthesis in the liver was significantly lowered by Se and in particular by Met. Liver Chol concentration was significantly higher in all the Se-supplemented C and M groups than in groups C15 and M15. Plasma Chol was, however, lowered. The uninfluenced expression of sterol-regulatory element-binding protein 2 and of hydroxymethyl-glutaryl-CoA reductase, the increased LDL receptor expression and the reduced expression of the hepatobiliary Chol exporter ATP-binding-cassette-transporter 8 (ABCG8) by Se and/or Met explain these findings. We conclude that the elevation of plasma HCys in rats by Se and Met results from a higher export into plasma. The fact that Se in particular combined with Met increases liver Chol but reduces plasma Chol should be addressed in future investigations focussing on the regulation of ABCG8, which is also selectively involved in the reverse transport of phytosterols in the small intestine.

In this work, gap states in doped and undoped a-SiGe:H alloys are examined by numerical simulations of sub-bandgap absorption spectra measured by the constant photocurrent method and photothermal deflection spectroscopy. Deconvolution methods, neglecting the condition of charge neutrality, can be used for a rough estimate of the defect density value but not for ob- taining detailed information on the distribution of gap states in undoped samples. Our numerical analysis uses adapted occupation statistics and takes into account the condition of charge neutrality. Good agreement between measured and simulated PDS and CPM spectra is obtained. For a certain composition, i.e. a certain bandgap, the investigation of doped films yields infor- mation on the density and the position of charged defect states in the bandgap. In addition, the density of neutral defect states can be derived from a comparison of CPM and PDS spectra. The results reveal the coexistence of charged and neutral defects. In doped as well as in undoped films, charged defect states dominate the defect density. In the investigated range of compo- sitions the defect distribution of a-SiGe:H is similar to those found in a-Si:H. The width of the defect distributions does not decrease with decreasing bandgap. No evidence for a different be- havior of Si- and Ge-related defect states can be found in sub-bandgap absorption spectra.