Interviews with the dead: using meta-life qualitative analysis to validate Hippocrates' theory of humours

BACKGROUND: Hippocrates devised his theory of the 4 humours (blood, phlegm, black bile and yellow bile) 24 centuries ago. Since then, medicine has evolved into a complex body of confusing and sometimes contradictory facts. The authors, seeing a need to determine the validity of his theory, hired a psychic. METHODS: The psychic interviewed 4 eminent ancient physicians, including Hippocrates. A randomized double-blind cross-over design was used for this meta-life qualitative analysis. RESULTS: All of the interviewees agreed that the theory of humours is an accurate model to explain disease and personality. INTERPRETATION: Hiring a psychic to conduct after-death interviews with key informants is a useful way to validate scientific theories.     

Neutral theory in macroecology and population genetics

Current neutral theory in macroecology has many parallels with neutral theory in population genetics, but it also has many distinct features that arise because it focuses mainly on questions at the community level rather than at the population level. Here we highlight the similarities and differences between these two bodies of theories from the aspects of the operational units, definitions of neutrality, basic parameters, driving forces, spatial structure and community assembly rules. Compared with neutral theory in population genetics, whose development spans more than 40 years, neutral theory in ecology, which is only a few years old, is still immature and under-developed. There are many opportunities for major theoretical contributions, some of which can be adopted directly from population genetics, while others will require new theoretical work. We critically discuss these opportunities and theoretical challenges in neutral macroecology, particularly in regard to effective community size, ecological drift, community differentiation and ecological dominance.     

The metabolism of naphthalene and its toxic effect on the eye

1. Naphthalene (1g./kg.) was fed daily by stomach tube to rabbits. 2. In more than half of the rabbits opacities in the lens and degeneration of the retina were visible in vivo. 3. Dissection of eye tissues revealed some or all of the following changes: a browning of the lens and eye humours, blue fluorescence of the eye humours and crystals in the retina and vitreous body. 4. The ascorbic acid concentration of the eye humours was decreased. 5. Some metabolites of naphthalene [1,2-dihydro-1,2-dihydroxynaphthalene, 2-hydroxy-1-naphthyl sulphate and (1,2-dihydro-2-hydroxy-1-naphthyl glucosid)uronic acid] are converted enzymically by the tissues of the eye into 1,2-dihydroxynaphthalene. 6. Changes in the eye are consistent with 1,2-dihydroxynaphthalene's being the primary toxic agent. The properties and reactions of this substance are described. 7. 1,2-Dihydroxynaphthalene is readily autoxidizable in neutral solution to form the yellow 1,2-naphthaquinone and hydrogen peroxide. This oxidation is reversed by ascorbate. 8. Ascorbate is oxidized catalytically by 1,2-naphthaquinone. This may account for the disappearance of ascorbate from the aqueous and vitreous humours of the eye after naphthalene feeding. It may also account for the appearance of crystals of calcium oxalate in the eye. 9. The brown colour of the lens of the naphthalene-fed rabbit is due to presence of naphthaquinone–protein compounds.     

Oribatid mites (Acari) from nests of some birds in South Vietnam

The fauna of oribatid mites in nests of the bar-bellied pitta, the blue-rumped pitta, and the whiterumped shama was studied at the Dong Nai Biosphere Reserve (South Vietnam). The data on the taxonomic composition, total number of species, dominant species, and their occurrence in nests are presented.     

A new method for estimating the axis of rotation and the center of rotation.

A new method is presented for estimating the parameters of two different models of a joint. The two models are: (1) A rotational joint with a fixed axis of rotation, also referred to as a hinge joint and (2) a ball and socket model, corresponding to a spherical joint. Given the motion of a set of markers, it is shown how the parameters can be estimated, utilizing the whole data set. The parameters are estimated from motion data by minimizing two objective functions. The method does not assume a rigid body motion, but only that each marker rotates around the same fixed axis of rotation or center of rotation. Simulation results indicate that in situations where the rigid body assumption is valid and when measurement noise is present, the proposed method is inferior to methods that utilize the rigid body assumption. However, when there are large skin movement artefacts, simulation results show the proposed method to be more robust.     

Study of biocomplexity in an aquatic ecosystem through ascendency

The ascendancy concept aims at quantitatively describing the growth and development of an ecosystem as whole. Growth is an increase in the total system throughflow, while development is taken to be a rise in the average mutual information inherent in the network flow structure. As an ecosystem matures and goes through a series of successional stages, its ascendancy exhibits a propensity to increase. In any ecosystem the equilibrium condition may gradually turn into a chaotic situation for different reasons. In this paper a model is proposed of an aquatic ecosystem comprising of three groups, viz., phytoplankton, zooplankton and fish. Rate parameters are changed according to the change of the size of the organisms. The model is run in different conditions with gradual decrement of the body sizes of zooplankton. Allometric principle of the relationship of body size of zooplankton and two rate parameters (growth rate and half saturation constant) are incorporated in this model. According to allometric principle gradual decrement of body sizes of zooplankton consequently increases the grazing rate and decreases the half-saturation constant of this organisms. The system exhibits different states (equilibrium point--stable limit cycle--doubling and ultimately chaos) by gradual increase of zooplankton grazing rate and decrease of half-saturation constant. This paper tests the high level of ascendancy of the systems at the edge of oscillation before starting of the chaos. This high level of throughflow and mutual information, i.e. Ascendency supports the hypothesis that the system can coordinate the most complex behavior and shows maximum biocomplexity in this situation.     

A sensitivity analysis method for the body segment inertial parameters based on ground reaction and joint moment regressor matrices

This paper presents a method allowing a simple and efficient sensitivity analysis of dynamics parameters of complex whole-body human model. The proposed method is based on the ground reaction and joint moment regressor matrices, developed initially in robotics system identification theory, and involved in the equations of motion of the human body. The regressor matrices are linear relatively to the segment inertial parameters allowing us to use simple sensitivity analysis methods. The sensitivity analysis method was applied over gait dynamics and kinematics data of nine subjects and with a 15 segments 3D model of the locomotor apparatus. According to the proposed sensitivity indices, 76 segments inertial parameters out the 150 of the mechanical model were considered as not influent for gait. The main findings were that the segment masses were influent and that, at the exception of the trunk, moment of inertia were not influent for the computation of the ground reaction forces and moments and the joint moments. The same method also shows numerically that at least 90% of the lower-limb joint moments during the stance phase can be estimated only from a force-plate and kinematics data without knowing any of the segment inertial parameters.     

On Carl Gegenbaur’s theory on head metamerism and the selection of taxa for comparisons

Summary After the rejection of the idealistic “vertebral theory of the skull,” the basic idea of the theory had been taken up again by the German morphologist Carl Gegenbaur. He proposed a metameric ordering system of the vertebrate head based on a comparative investigation of selachians. This “segmentation theory of the vertebrate head” had a stimulating effect on comparative anatomy. Traces of the basic ideas are still inherent in the biological sciences. Despite the fact that Carl Gegenbaur proposed a rather phylogenetic approach, his systematic investigations remained on a typological level. It is argued herein, that the reason for that was his inability to perform his comparisons independent of a rather intuitive a priori hypothesis about phylogenetic relationships, thus leaving no possibilities for testing homologies. This is exemplified by Carl Gegenbaur’s choice of species for comparative work as well as his use of these species in comparative work. Choosing species for comparisons is discussed.     

Macroecology and the hierarchical expansion of evolutionary theory

The constraint envelope describing the relationship between geographical range size and body size has usually been explained by a minimum viable population size model, furnishing a strong argument for species selection if geographical range size turns out to be ‘heritable’. Recent papers have questioned this assumption of nonzero geographical range heritability at a phylogenetic level, meaning that the logic that constraint envelopes provide support for higher‐level selection fails. However, I believe that analysis of constraint envelopes can still furnish insights for the hierarchical expansion of evolutionary theory because the fitness furnished by variation in body size, which is frequently measured as a highly ‘heritable’ trait at the species level, can be partitioned into anagenetic and cladogenetic components. The constraint envelope furnishes an explicit mechanism for large‐body biased extinction rates influencing the distribution of body size. More importantly, it is possible to envisage a scenario in which anagenetic trends driving an increase in body size in higher latitudes within species (Bergmann's rule) are counteracted by available habitat area or continental edges constraining overall species distribution in these higher latitudes, increasing the probability of extinction. Under this combined model, faunas at higher latitudes and under habitat constraints may reach equilibrium points between these opposing hierarchical adaptive forces at smaller body size than faunas with less intense higher‐level constraints and will tend to be more right‐skewed.     

Antenna modeling considerations for accurate SAR calculations in human phantoms in close proximity to GSM cellular base station antennas

International bodies such as International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute for Electrical and Electronic Engineering (IEEE) make provision for human exposure assessment based on SAR calculations (or measurements) and basic restrictions. In the case of base station exposure this is mostly applicable to occupational exposure scenarios in the very near field of these antennas where the conservative reference level criteria could be unnecessarily restrictive. This study presents a variety of critical aspects that need to be considered when calculating SAR in a human body close to a mobile phone base station antenna. A hybrid FEM/MoM technique is proposed as a suitable numerical method to obtain accurate results. The verification of the FEM/MoM implementation has been presented in a previous publication; the focus of this study is an investigation into the detail that must be included in a numerical model of the antenna, to accurately represent the real-world scenario. This is accomplished by comparing numerical results to measurements for a generic GSM base station antenna and appropriate, representative canonical and human phantoms. The results show that it is critical to take the disturbance effect of the human phantom (a large conductive body) on the base station antenna into account when the antenna-phantom spacing is less than 300 mm. For these small spacings, the antenna structure must be modeled in detail. The conclusion is that it is feasible to calculate, using the proposed techniques and methodology, accurate occupational compliance zones around base station antennas based on a SAR profile and basic restriction guidelines.     

Anorectic agents lower a body weight set point

A new theory of the action of “appetite suppressant” agents proposes that they act primarily by lowering a body weight set point and only secondarily by suppressing appetite (1, 2). Evidence is reviewed that body weight is regulated in animals rendered overwieght or underweight by hypothalmic lesions as well as in those of normal weight. A very recent study can be interpreted as indicating that both amphetamine and fenfluramine lower a body weight set point in experimental animals (3). Clinical evidence also supports this theory, notably the rapid regaining of body weight following withdrawal of “appetite-suppressant” medication, in contrast to the relative stability of weight losses achieved without medication (4).This set point explanation of the rebound in body weight following withdrawal of medication has not been proposed before. One reason may be the long-standing belief that tolerance to this medication develops very rapidly. For, if an agent quickly lost its effectiveness, it could not lower a set point over long periods of time and withdrawing it would not result in an elevation of that set point. At least three clinical findings argue against the development of tolerance. In addition to the rebound in body weight, they include little slowing in the rate of weight loss and no increase in hunger during several months of treatment with fenfluramine (2, 4). If tolerance had developed, slowing of the rate of weight loss and increase in hunger would have been expected.This theory and these findings suggest a radical revision in prescribing practices for “appetite-suppressant” medication: use it on a chronic basis or not at all. The reason for discontinuing the current practice of restricting it to short-term use is the opposite of that currently invoked: not because of the development of tolerance, but precisely because tolerance does $\text{not}$ develop. If medication lowers a body weight set point, discontinuing the medication, with elevation of the set point to its previous level, subjects patients to powerful pressures to regain the weight they had lost. The chronic use of “appetite-suppressant” medication should be seriously considered. The benefits may well outweight the risks, particularly for some obese people.     

Growth and development of children with a special focus on sleep

The first two decades of life are characterised complex biological processes involving growth and maturation as well as differentiation. The Central Nervous System (CNS) where among others internal and external stimuli are integrated and responses of the body are prepared starts to evolve quite early during ontogenesis. One of the complex behaviours, which are regulated by the brain, is the sleep-wake cycle.The discussion of age-related changes in sleep comprises changes at the physiological level (e.g. changes in the frequency and amplitude of EEG signal, as well as development and distribution of sleep stages), changes in the corresponding behaviour (e.g. changes in the absolute amount of sleep and its distribution in 24 h perspective), and finally the subjective perception of sleep and sleep as a measure of well-being.Studies on the impact of a specific factor on sleep during childhood and adolescence have to consider chronological and biological age as well as sex as relevant biological parameters. Even when these factors are controlled for large interindividual differences persist, that is why prospective instead of cross-sectional approaches should be used whenever possible. Furthermore, it has to be distinguished between sleep assessed at the level of brain functioning (i.e. by polysomnography), which gives information on effects at the physiological level and at the level of self-assessment, which focuses on behaviour. Both, sleep at the subjective as well as at the objective level, can to a considerable degree be affected by life style factors, which hence have to be considered as potential confounders.     

Entropy and community pattern analysis

A conceptual framework for the analysis of community types pattern (mosaic) is proposed and discussed in this paper. Within this framework, the pattern is viewed as a system whose freedom to take any particular state from among a set of possible microstates is restrained by ecological factors. This allows for the operationalization of an analytical procedure (PEGASE) based on information theory whereby the entropy of the pattern is reduced by a negentropy provided by various environmental factors.The introduction of these factors in a stepwise manner gives this method two of its essential characters: (i) its multivariate nature and (ii) the classification of sites in a divisive manner. Given a set of environmental factors, the level of organization of the pattern can be measured by the global environmental negentropy.Several properties of this model are discussed. Similarly to some early attempts at biophysical classification, the “Pegase” procedure emphasizes the ecological relationships. Indeed, it classifies sites into a set of site type which allows for the best prediction of community types. On the other hand, its basic structure is similar to that of a multiple regression model, without requiring any of the assumptions on data structure and distribution that multiple regression requires.     

Homeostasis in the vertebrate lens: mechanisms of solute exchange

The eye lens is avascular, deriving nutrients from the aqueous and vitreous humours. It is, however, unclear which mechanisms mediate the transfer of solutes between these humours and the lens' fibre cells (FCs). In this review, we integrate the published data with the previously unpublished ultrastructural, dye loading and magnetic resonance imaging results. The picture emerging is that solute transfer between the humours and the fibre mass is determined by four processes: (i) paracellular transport of ions, water and small molecules along the intercellular spaces between epithelial and FCs, driven by Na(+)-leak conductance; (ii) membrane transport of such solutes from the intercellular spaces into the fibre cytoplasm by specific carriers and transporters; (iii) gap-junctional coupling mediating solute flux between superficial and deeper fibres, Na(+)/K(+)-ATPase-driven efflux of waste products in the equator, and electrical coupling of fibres; and (iv) transcellular transfer via caveoli and coated vesicles for the uptake of macromolecules and cholesterol. There is evidence that the Na(+)-driven influx of solutes occurs via paracellular and membrane transport and the Na(+)/K(+)-ATPase-driven efflux of waste products via gap junctions. This micro-circulation is likely restricted to the superficial cortex and nearly absent beyond the zone of organelle loss, forming a solute exchange barrier in the lens.     

Chronobiology of human blood pressure in the light of static (room-restricted) automatic monitoring

Systematic 24-h automatic physiologic monitoring has obvious merits, even without rhythmometry. It can lead more readily to the recognition of odd-hour blood pressure elevation (e.g., of 'evening' or 'morning' hypertension). Such a condition can constitute an initial diagnosis or it may be found under treatment that may seem to be satisfactory if its effects are assessed only on the basis of a conventional check at a casual, possibly 'wrong' time. The mere inspection of a 24-h record, however, does not necessarily allow one to make objective quantitative global statements as to a change in pattern, e.g., after a given intervention. This paper illustrates how by rhythmometry, some of the uncertainties of a subjective interpretation of a record may be removed by practitioners of medicine, as well as basic scientists interested in mechanisms of blood pressure variability. This is possible since a large part of blood pressure variability can be accounted for by its circadian periodic behavior. We herein present a methodology for data collection and analysis that allows the objective quantification of blood pressure rhythm parameters in health and disease and the derivation of reference standards for such parameters. The chronobiologic approach thus makes it possible to define 'hypertension' objectively, and to distinguish between 'mesor-' and 'amplitude-hypertension', i.e., between an elevation in overall mean and one in the predictable extent of variability. Moreover, chronobiology has shown that mesor-hypertension may be preceded by an elevation in circadian amplitude only (amplitude-hypertension). Parameter tests readily allow the assessment, in relation to an objective reference standard, of these conditions, with a defined probability. Similarly, response to drug or non-drug therapy can be established and a given intervention optimized by timing treatment. Using chronobiologic tools in cardiovascular research provides new insights into possible mechanisms underlying mesor- and amplitude-hypertension. The teaching of the chronobiology of blood pressure and autorhythmometry in schools has been proven to be feasible and has been recommended as a step toward self-help for health care.     

Modeling composting kinetics: A review of approaches

Composting kinetics modeling is necessary to design and operate composting facilities that comply with strict market demands and tight environmental legislation. Current composting kinetics modeling can be characterized as inductive, i.e. the data are the starting point of the modeling process and determine the type of model used. It is argued that the inductive empirical approach has been developed to its limit of practicality. Further progress is not expected because of limits in measurement techniques and the resources needed to perform all experiments needed.Contrary to the inductive, the deductive modeling approach uses the existing theory as its starting point for model development. Deductive models of realistic situations contain many basic parameters representing the theoretical basis. These basic parameters however tend to be non-identifiable, limiting practical application.To overcome this problem, it is proposed that the basic parameters in the deductive model must be combined to a smaller number of so-called combined parameter that are identifiable. In this way a model is developed that can incorporate both the theoretical knowledge introduced via the basic parameter and the information of data as represented by the identifiable combined parameters.As an example of how information of both theory and data can be used, the case of the temperature effect on the composting rate is analyzed. The temperature effect is quantified as the activation energy E, a parameter derived from the well-known Arrhenius equation. The theoretical analysis shows that the E-value changes strongly during the process, which is very remarkable, as the E value of basic parameter remains constant. These results are in accordance with literature findings. The results suggest that the multiplicative approach used in first-order modeling should be reconsidered, as both the literature findings as well as the theoretical analysis of the model predict a shift in E-value. Missing a shift in the E-value could lead for instance to instability in temperature control algorithms.     

Biomechatronics--assisting the impaired motor system

Biomechatronics concerns the interdisciplinary field of interaction with the human neuromuscular-skeletal system with the objective to assist impaired human motor control. In this field technology is developed that integrates neuroscience, robotics, interface and sensor technology, dynamic systems and control theory. The primary issue in this field concerns the concepts of assisting impaired human motor function. The secondary, derived, issue concerns possible methods of interfacing with the human body at all hierarchical levels of the human motor system. The application of motor assist systems may serve several goals: it can take over part of the affected motor control, enable the physiological motor system to perform the desired function or aid in training the impaired physiological system. The progress in these issues are reviewed and their potential implications for assistance of the impaired human motor system are discussed.     

Invariance of visual operations at the level of receptive fields

The brain is able to maintain a stable perception although the visual stimuli vary substantially on the retina due to geometric transformations and lighting variations in the environment. This paper presents a theory for achieving basic invariance properties already at the level of receptive fields. Specifically, the presented framework comprises (i) local scaling transformations caused by objects of different size and at different distances to the observer, (ii) locally linearized image deformations caused by variations in the viewing direction in relation to the object, (iii) locally linearized relative motions between the object and the observer and (iv) local multiplicative intensity transformations caused by illumination variations. The receptive field model can be derived by necessity from symmetry properties of the environment and leads to predictions about receptive field profiles in good agreement with receptive field profiles measured by cell recordings in mammalian vision. Indeed, the receptive field profiles in the retina, LGN and V1 are close to ideal to what is motivated by the idealized requirements. By complementing receptive field measurements with selection mechanisms over the parameters in the receptive field families, it is shown how true invariance of receptive field responses can be obtained under scaling transformations, affine transformations and Galilean transformations. Thereby, the framework provides a mathematically well-founded and biologically plausible model for how basic invariance properties can be achieved already at the level of receptive fields and support invariant recognition of objects and events under variations in viewpoint, retinal size, object motion and illumination. The theory can explain the different shapes of receptive field profiles found in biological vision, which are tuned to different sizes and orientations in the image domain as well as to different image velocities in space-time, from a requirement that the visual system should be invariant to the natural types of image transformations that occur in its environment.