Relationship between postabsorptive respiratory exchange ratio and plasma free fatty acid concentrations

The relationship between overnight postabsorptive (fasting) respiratory exchange ratio (RER) and plasma FFA concentrations was addressed using data from three separate protocols, each of which involved careful control of the antecedent diet. Protocol 1 examined the relationship between fasting RER and the previous daytime RER. In Protocol 2 fasting, RER and plasma palmitate concentrations were measured in 29 women and 31 men (body mass index <30 kg·m⁻²). Protocol 3 analyzed data from Nielsen et al. (Nielsen, S., Z. K. Guo, J. B. Albu, S. Klein, P. C. O''Brien, M. D. Jensen. 2003. Energy expenditure, sex and endogenous fuel availability in humans. J. Clin. Invest. 111: 981-988.) to understand how fasting RER and palmitate concentrations relate within individuals during four consecutive measurements. The results were as follows: 1) Fasting RER was correlated (r = 0.74, P < 0.001) with the previous day''s average RER, and less so with RER variability. 2) Fasting RER was correlated (r = −0.39, P = 0.007) with fasting plasma palmitate concentrations. 3) The pattern of the RER/palmitate relationship was similar within individuals and between individuals; a negative slope was observed significantly more often than a positive slope (χ² test; P < 0.001). Our findings suggest that, despite a fixed food quotient, the slight departures from energy equilibrium in a controlled General Clinical Research Center environment can effect plasma FFA concentrations. We suggest that including indirect calorimetry as part of FFA metabolism studies may aid in data interpretation.     

Contributions to the sociology and chorology of contrasting plant communities in the southern part of the ‘Wienerwald’ (Austria)

Five plant communities contrasting in successional status and human impact from the southern part of the ‘Wienerwald’ (Austria) are analyzed using vegetation relevés, spectra of area types and a newly proposed disjunction quotient. A climax community (Asperulo-Fagetum), a subclimax community (Querco-Carpinetum s.l.), an anthropogenous substitute community (Mesobromion) and two natural, non-climax permanent communities (Euphorbio saxatilis-Pinetum nigrae and Fumano-Stipetum eriocaulis) are recognized. The disjunction quotient is defined as the number of partial (discontinous) areas divided by the size of the total area of distribution of a species. In particular, the average disjunction quotients of the species in the first two communities reflect relatively table environments only slightly influenced by man, with many ancient, stable taxa. These communities are characterized by species with well-delimited, stable distribution areas. The species in the Mesobromion community have very low average disjunction quotients as its component species are widely and continuously distributed and are often promoted by man. In contrast to these communities, the species linked to the natural permanent, non-climax communities of extreme habitats, have high distribution quotients i.e. small, disconinuous areas; this illustrates the relic character of these plant communities and of the eastern edge of the Alps is a whole. Using the highly variable disjunction quotient of all species and communities examined, the concepts of climax and permanent communities (of different origin) are discussed with regard to European conditions.     

Validation of the first step of the heuristic refinement method for the derivation of solution structures of proteins from NMR data

A new method for the analysis of NMR data in terms of the solution structure of proteins has been developed. The method consists of two steps: first a systematic search of the conformational space to define the region allowed by the initial set of experimental constraints, and second, the narrowing of this region by the introduction of additional constraints and optional refinement procedures. The search of the conformational space is guided by heuristics to make it computationally feasible. The method is therefore called the heuristic refinement method and is coded in an expert system called PROTEAN. The paper describes the validation of the first step of the method using an artificial NMR data set generated from the known crystal structure of sperm whale carbon monoxymyoglobin. It is shown that the initial search procedure yields a low-resolution structure of the myoglobin molecule, accurately reproducing its main topological features, and that the precision of the structure depends on the quality of the initial data set.     

The total burden of rare,non-synonymous exome genetic variants is not associated with childhood or late-life cognitive ability

Human cognitive ability shows consistent, positive associations with fitness components across the life-course. Underlying genetic variation should therefore be depleted by selection, which is not observed. Genetic variation in general cognitive ability (intelligence) could be maintained by a mutation–selection balance, with rare variants contributing to its genetic architecture. This study examines the association between the total number of rare stop-gain/loss, splice and missense exonic variants and cognitive ability in childhood and old age in the same individuals. Exome array data were obtained in the Lothian Birth Cohorts of 1921 and 1936 (combined N = 1596). General cognitive ability was assessed at age 11 years and in late life (79 and 70 years, respectively) and was modelled against the total number of stop-gain/loss, splice, and missense exonic variants, with minor allele frequency less than or equal to 0.01, using linear regression adjusted for age and sex. In both cohorts and in both the childhood and late-life models, there were no significant associations between rare variant burden in the exome and cognitive ability that survived correction for multiple testing. Contrary to our a priori hypothesis, we observed no evidence for an association between the total number of rare exonic variants and either childhood cognitive ability or late-life cognitive ability.     

Animal learning and intelligence

The ability to learn is common to most animal species: the need to exploit past experience being obviously extremely important for survival, many animals have evolved ways of coping with it. Although the complexity of learning needed for optimal survival may be different in different species, the basic mechanisms appear to be fairly constant even in phylogenetically distant ones. This homogeneity across species in learning mechanisms is in some ways surprising in view of the large phylogenetic differences and of the considerable variability not only in the general plan of their bodily structures, but also, more specifically, in their neural organization and in their behavioral adaptations. One possible explanation is that animals have acquired learning very precociously, and that the original and basic mechanisms have proved so efficient and faultproof as to be preserved from then on without any significant modification. Most researchers of the subject seem to accept the equation «intelligence=learning capability», operationally very useful because it leads to a variety of formal tests. Some researchers, stressing that behavior is subject to the same evolutionary principles as any other character of the organism and acknowledging some problems in the accepted laws of learning, have tried to find a satisfactory answer to the question of animal intelligence by attempting a synthesis between the concepts of animal learning psychology and those of ethology. To some extent, dissatisfaction with established learning theories originated within the theories themselves: the study of phenomena such as autoshaping, selective attention, preferential learning of some responses amongst the many possible, conditioned learning of taste aversions, etc. Further difficulties for conditioning theories arose from the discovery of ethological phenomena. Other researchers have attempted to check the hypothesis that animals possess cognition. A number of complex experimental situtations have been devised to this purpose, but the results still are far from conclusive.     

Development of tool use in a macaque and a gorilla

The development of the capacity to use a stick as a tool was tested in a macaque (Macaca fuscata) and a gorilla (Gorilla gorilla gorilla) infants that had previously shown to be able to use strings and supports as dragging tools. Subjects were tested between 15 and 38 months of age. Different levels of competence between the subjects emerged over testing. The macaque developed a stereotyped strategy to cope with the problem, only getting random successes, whilst the gorilla developed a flexible strategy and revealed to be able to mentally represent the solution of the problem. In fact, when not successful using the stick, the gorilla thought out an alternative strategy, choosing and adapting a new object to use it as a tool.     

Effects of rapid changes in oxygen concentration on the respiration of carrot roots

Rates of CO₂ production and O₂ consumption from aged disks of carrot ( Daucus carota L.) root tissues were measured for 4 h after they were transferred from 21% to 0, 1, 2, 4 or 8% O₂ in gas mixtures. A transient peak in the rate of CO₂ production started 5 to 7 min after transfer to 2% or lower O₂ mixtures and peaked at 50 min. After the peaks in CO₂ production from the 0, 1 and 2% O₂ treatments and after the stable production from the 4 and 8% O₂ treatments, the rate of CO₂ production from all low O₂ treatments started to decline at 50 min, reaching stable rates by 160 to 240 min. Concentrations of lactate and ethanol that were significantly higher than the 21% O₂ controls had started to accumulate in disks between 10 and 50 min after exposure to atmospheres containing 2% or less O₂. Production of CO₂ started to increase 5 to 7 min after transfer to 0, 1 and 2% O₂, while the initial decline and then rise in pH and the accumulation of ethanol did not occur until 30 min after the change in atmosphere. Ethanol accumulation paralleled the increase in pH; first at 0.4 μmol g⁻¹ h⁻¹ from 30 to 60 min as the pH shifted from 5.97 to 6.11, and then at 0.08 μmol g⁻¹ h⁻¹ from 60 to 100 min as the pH stablized around 6.12. The peak at 50 min in CO₂ production roughly coincided with the shift from the rapid to the slow change in pH and ethanol accumulation.     

Personal reflections on the nature of intelligence in humans and machines

Computers, the human mind, and social systems have common problems of inadequate memory and insufficient data manipulation speed. In each of these domains, information compression techniques have evolved to reduce storage and processing needs. Among the techniques for information compression, coding of information in procedures stands out as exceptionally powerful. Procedural information coding also gives rise to behavior that may be defined as intelligent. It is found in the human mind, in machines and in social systems. Its use in human thought is aided by language development which promotes regular review of abstract procedures. A practical consequence of better understanding of procedural information coding is the possibility of training people to exhibit greater mental capacity, a controversial possibility. This paper explores the impact of data processing resource limitations, data compression and procedural thinking in men and machines.