Measuring alignment of the hindfoot

In subtalar arthrodesis operations, correction of the hindfoot alignment is performed in about half of the cases. To improve the quality of the operation, a measurement system was developed which reliably measures the hindfoot angle pre-, per-, and postoperatively. This device was evaluated by measuring subjects in standing weightbearing position and in prone nonweightbearing position. The results were compared with hindfoot angles constructed on posterior photographic images. The results are similar to other studies (all maximum values): intratester accuracy 1.4 degrees, intertester accuracy 2.2 degrees, intratester reliability 0.9, and intertester reliability 0.74. The proposed device will improve the quality of correction, because it enables peroperative measurement of hindfoot alignment.     

Measuring the influence of mycorrhizas

'The view that nutrient acquisition by most plants growing in natural ecosystems is mediated by mycorrhiza-forming symbiotic fungi is now largely accepted' (Read, 2000). Is this bold claim really true for the whole suite of mineral nutrients that plants require? The case is strongest for nutrients that are not very mobile in soil, especially when present in growth-limiting amounts, and phosphate (P) is the classic example. Arbuscular mycorrhizas are by far the most widespread mycorrhizal symbioses, and the ability of arbuscular mycorrhizal (AM) fungi to take up soil nutrients such as P and transfer them to the host plant is an area of intense research. However, there is great variation in the extent to which AM plants benefit in measurable terms from the symbiosis under a given set of environmental conditions, and a paper in this issue, by Koide et al ., addresses this problem (Koide et al ., pp. 163–168). The variability is especially apparent in the field, thus obscuring the possible roles of mycorrhizas in community structure and succession (Fitter, 1985; McGonigle, 1988).     

Measuring the costs of reproduction

The measurement of costs of reproduction is of interest because such costs are generally assumed by life history theory. There is some controversy concerning how to measure costs: common methods include experimental manipulations of life history, such as preventing some individuals from reproducing, or estimates of genetic correlations. These two methods often yield similar results, suggesting that one can serve as a substitute for the other. There are now experiments which demonstrate that there are different mechanisms underlying the response to an experimental manipulation versus a genetic correlation, so the two methods are not equivalent in estimating costs.     

Measuring the distribution of spitefulness

Spiteful, antisocial behavior may undermine the moral and institutional fabric of society, producing disorder, fear, and mistrust. Previous research demonstrates the willingness of individuals to harm others, but little is understood about how far people are willing to go in being spiteful (relative to how far they could have gone) or their consistency in spitefulness across repeated trials. Our experiment is the first to provide individuals with repeated opportunities to spitefully harm anonymous others when the decision entails zero cost to the spiter and cannot be observed as such by the object of spite. This method reveals that the majority of individuals exhibit consistent (non-)spitefulness over time and that the distribution of spitefulness is bipolar: when choosing whether to be spiteful, most individuals either avoid spite altogether or impose the maximum possible harm on their unwitting victims.     

Measuring the cost of reproduction

Gravid and barren Daphnia pulex were exposed to a variety of predators in laboratory aquaria. Small fish (guppies, sticklebacks and shiner fry) consistently preferred the gravid females, establishing the existence of a behavioural cost of reproduction. However, no such cost was associated with predation by more efficient visual predators (sunfish) or by nonvisual predators (hydras), and the excess of gravid females eaten by backswimmers was found to be attributable to their distribution in the water column. Moreover, the cost associated with predation by small fish was observed only when the Daphnia were presented against a light background, and was abolished when a dark background was substituted. In a further series of experiments with guppies we attempted to show that each egg added to the brood caused a decrease in survival; in two such experiments survival rate was related to body size but not to fecundity, while in a third the effect of body size did not appear, and a negative correlation between survival and fecundity could be demonstrated. Although these experiments unambiguously demonstrate a cost of reproduction they also illustrate the elusiveness of the phenomenom and emphasize the need to develop theories which specify the type and magnitude of costs generated by different ways of life.     

Measuring the cost of reproduction

Summary The timing of the first two broods and the number and size of offspring in each was measured in a series of three experiments for monoclonal cultures of the cladoceran Daphnia pulex reared under standard conditions of ration, temperature and photoperiod. The pattern of total correlations between pairs of life-history variables did not in general support predictions made by hypotheses of reproductive cost. A partial correlation analysis, involving initial size and subsequent growth as well as the life history variables themselves, was performed in an attempt to avoid potential fallacies introduced by the use of total correlations. The only consistent effect found was a positive relationship between the age at reproductive maturity and the mean size of offspring in the first brood. The structure of this segment of the life history is strongly influenced by interactions between size and reproduction, to an extent that precludes the use of simple optimality models.     

Measuring smells

Olfaction consists of a set of transforms from a physical space of odorant molecules, through a neural space of information processing, and into a perceptual space of smell. Elucidating the rules governing these transforms depends on establishing valid metrics for each of the three spaces. Here we first briefly review the perceptual and neural spaces, and then concentrate on the physical space of odorant molecules. We argue that the lack of an agreed-upon odor metric poses a significant obstacle toward understanding the neurobiology of olfaction, and suggest two alternative odor metrics as possible solutions.     

Measuring Gender

Over the past several years, various operational definitions of gender have been used in studies of gender conformity in homosexual males. The goal of these studies is to demonstrate that childhood gender nonconformity (CGN) is either the proximate cause of adult homosexuality or an intermediate step in a biologically mediated process. The hypothesis of a causal connection between the development of gender and sexual orientation is embedded within the context of a biological (evolutionary) understanding of human behavior. Thus, testing the hypothesis of a causal connection between CGN and sexuality requires a concept of gender that is compatible with the basic principles of biological causation and our current understanding of evolutionary processes. I will argue that the concepts of gender used in the attempt to demonstrate a causal connection between CGN and sexual orientation are inappropriate because they provide no uniform, consistent method for identifying and measuring the biologically significant components of gender. I will also argue that the concept of gender that does emerge from these studies suggests an hypothesis about the connection between sexuality and gender that is not consistent with the cross-gendered theory of the etiology of homosexuality.     

Measuring noise

High levels of noise encountered both in leisure activities and at workplaces can be somewhat annoying, but they can also cause hearing damage. In order to lessen these risks, some physical characteristics of the sound phenomenon need to be understood. The level of a sound is given in dB, a logarithmic unit in which simple addition is not available : 100 dB + 100 dB = 103 dB. The highest level of noise which can be tolerated by the human ear is considered to be 120 dB. Another component of sound characteristics is the frequency, which describes the height of a sound. The frequency is given in Hz, the human hearing field is comprised in the range of 20 to 20,000 Hz. Regarding the sensitivity of the ear, depending on the frequency, acusticians use a weighed dB, called dB(A), which takes into account a lower risk to hearing below 500 Hz and above 6 kHz. They also integrate the energy measured during a period of time to take the fluctuation of usual noise levels into account. So that currently, the levels of noise are often given in LAeq (equivalent to the level of continuous noise given in dBA). For moderate levels of noise, another weighted filter is used in sound level meters : the C curve, because low frequencies, although they are less dangerous for the ear, are more disturbing. In every day life, we sometimes have noise levels reaching 100 dB, and even 120 dB (fire alarms). Amplified music can reach 110 dBA, but a French regulation limits the output of PCPs (Walkmans) to 100 dB and the levels in concerts and discotheques to 105 dBA. At the workplace, the maximum level of noise allowed by French Law is 90 dBA for an 8 hour exposure, and 140 dB for peaks. In order to improve the protection of all workers in the EC, a recent European Directive will decrease the maximum level to 87 dBA before March 2006.