Preface

The legal process is often invoked to resolve scientific or economic problems such as may arise when a bridge collapses, or an aeroplane crashes, or a ship sinks; or when a mishap occurs on the operating table; or when patent protection is sought for an invention claimed to be novel; or when it is necessary to assess the effect of a commercial practice on competition in a market; or when a baby dies, for no apparent reason, in its cot; or when it is sought to identify a fingerprint on a murder weapon.     

The effect of energy reserves and food availability on optimal immune defence

In order to avoid both starvation and disease, animals must allocate resources between energy reserves and immune defence. We investigate the optimal allocation. We find that animals with low reserves choose to allocate less to defence than animals with higher reserves because when reserves are low it is more important to increase reserves to reduce the risk of starvation in the future. In general, investment in immune defence increases monotonically with energy reserves. An exception is when the animal can reduce its probability of death from disease by reducing its foraging rate. In this case, allocation to immune defence can peak at intermediate reserves. When food changes over time, the optimal response depends on the frequency of changes. If the environment is relatively stable, animals forage most intensively when the food is scarce and invest more in immune defence when the food is abundant than when it is scarce. If the environment changes quickly, animals forage at low intensity when the food is scarce, but at high intensity when the food is abundant. As the rate of environmental change increases, immune defence becomes less dependent on food availability. We show that the strength of selection on reserve-dependent immune defence depends on how foraging intensity and immune defence determine the probability of death from disease.     

Conflict and co-operation in White Cloud Mountain minnow schools

Schooling fish do not always behave co-operatively, and conflict is particularly evident when individuals compete for limited resources. In White Cloud Mountain minnows, Tanichrhys albonubes , aggression is associated with the defence of potential spawning sites. Agonistic encounters between males are more prevalent when available habitat is reduced and when the number of spawning sites (patches of weed) is restricted. Conversely, competition diminishes when the fish are in a potentially threatening situation, e.g. when they are exploring a new environment.     

Generalized estimating equations for ordinal categorical data: arbitrary patterns of missing responses and missingness in a key covariate

We propose methods for regression analysis of repeatedly measured ordinal categorical data when there is nonmonotone missingness in these responses and when a key covariate is missing depending on observables. The methods use ordinal regression models in conjunction with generalized estimating equations (GEEs). We extend the GEE methodology to accommodate arbitrary patterns of missingness in the responses when this missingness is independent of the unobserved responses. We further extend the methodology to provide correction for possible bias when missingness in knowledge of a key covariate may depend on observables. The approach is illustrated with the analysis of data from a study in diagnostic oncology in which multiple correlated receiver operating characteristic curves are estimated and corrected for possible verification bias when the true disease status is missing depending on observables.     

The feeling of dampness at low temperatures

The widely held view that in cold weather one feels colder when the atmosphere is damp than when it is dry was investigated on clothed subjects. Subjective coldness and dampness, determined by a panel of six people who walked about half a mile in the open in winter, were compared with measurements of temperature, relative humidity, and other meteorological variables. The panellists comments showed that when the weather is cold, people think it is damp when the sky is overcast, irrespective of relative humidity. However, when this factor has been allowed for there still appears to be some correlation between subjective dampness and relative humidity. Relative humidity does appear to have an effect on how cold one feels at low temperatures, but only to a limited extent, and in the opposite direction to popular belief.     

Survey of the Influence of the Width of Urban Branch Roads on the Meeting of Two-Way Vehicle Flows

Branch roads, which are densely distributed in cities, allow for the flow of local traffic and provide connections between the city and outlying areas. Branch roads are typically narrow, and two-way traffic flows on branch roads are thus affected when vehicles traveling in opposite directions meet. This study investigates the changes in the velocities of vehicles when they meet on two-way branch roads. Various widths of branch roads were selected, and their influence on traffic flows was investigated via a video survey. The results show that, depending on the average vehicle velocity, branch roads require different widths to prevent a large decrease in velocity when vehicles meet. When the velocity on a branch road is not high (e.g., the average velocity without meeting is approximately 6 m/s), appropriately increasing the road width will notably increase the meeting velocity. However, when the velocity is high (e.g., the average velocity without meeting is greater than 10 m/s), there is a large decrease in velocity when meeting even if the road surface is wide (6.5 m). This study provides a basis for selecting the width of urban branch roads and the simulation of bidirectional traffic on such roads.     

细菌视紫红质的两种光电微分响应及其机制

利用MATLAB软件对细菌视紫红质 (BR)膜光电器件的脉冲响应实验数据进行拟合 ,得到器件的冲激响应函数。据此用SIMULINK模块构造出了反映BR光电器件特性的仿真系统。利用此系统对不同间断光入射BR光电器件时的输出响应信号进行了仿真计算。通过分析得出结论 :以前所描述的微分响应 (发生在毫秒到秒的时间量级 ,在光打开时产生一个正脉冲 ,在光关掉时产生一个负脉冲 )并非BR分子固有的特性 ,部分是由于测量电路引起的。BR分子本身特性引起的微分响应是发生在微秒时间量级 ,而且在光打开时产生一个负脉冲 ,在光关掉时产生一个正脉冲。对这两种微分响应产生的机制分别进行了探讨     

Does Spatial Locative Comprehension Predict Landmark-Based Navigation?

In the present study we investigated the role of spatial locative comprehension in learning and retrieving pathways when landmarks were available and when they were absent in a sample of typically developing 6- to 11-year-old children. Our results show that the more proficient children are in understanding spatial locatives the more they are able to learn pathways, retrieve them after a delay and represent them on a map when landmarks are present in the environment. These findings suggest that spatial language is crucial when individuals rely on sequences of landmarks to drive their navigation towards a given goal but that it is not involved when navigational representations based on the geometrical shape of the environment or the coding of body movements are sufficient for memorizing and recalling short pathways.     

The role of the excision and error-prone repair systems in mutagenesis by fluorinated quinolones in Salmonella typhimurium.

Patterns of reversion produced by ciprofloxacin, enoxacin and ofloxacin in Salmonella typhimurium strains carrying the hisG428 ochre mutation have been studied. These fluorinated quinolones produce a significant increase in reversion of this mutation, even when it is located on the chromosome. Nevertheless, reversion is higher when the hisG428 mutation is on the multicopy plasmid pAQ1 than when it is on the chromosome. Reversion of hisG428 induced by fluorinated quinolones is abolished both in a uvrB genetic background and in the absence of the plasmid pKM101. Therefore, mutagenesis produced by fluorinated quinolones in the Salmonella mutagenicity assay is significantly affected by both the excision repair and the error-prone repair systems. Furthermore, fluorinated quinolones are also detected as moderate mutagens with the base substitution hisG46 mutation when both repair systems are functional in the tester strain.     

Optimal escape theory predicts escape behaviors beyond flight initiation distance： risk assessment and escape by striped plateau lizards Sceloporus virgatus

Escape theory predicts that flight initiation distance (FID=distance between predator and prey when escape begins) is longer when risk is greater and shorter when escape is more costly. A few tests suggest that escape theory applies to distance fled. Escape models have not addressed stochastic variables, such as probability of fleeing and of entering refuge, but their economic logic might be applicable. Experiments on several risk factors in the lizard Sceloporus virgatus confirmed all predictions for the above escape variables. FID was greater when approach was faster and more direct, for lizards on ground than on trees, for lizards rarely exposed to humans, for the second of two approaches, and when the predator turned toward lizards rather than away. Lizards fled further during rapid and second consecutive approaches. They were more likely to flee when approached directly, when a predator turned toward them, and during second approaches. They were more likely to enter refuge when approached rapidly. A novel finding is that perch height in trees was unrelated to FID because lizards escaped by moving out of sight, then moving up or down unpredictably. These findings add to a growing body of evidence supporting predictions of escape theory for FID and distance fled. They show that two probabilistic aspects of escape are predictable based on relative predation risk levels. Because individuals differ in boldness, the assessed optimal FID and threshold risks for fleeing and entering refuge are exceeded for an increasing proportion of individuals as risk increases[Current Zoology 55(2):123-131,2009].     

Cataglyphis desert ants improve their mobility by raising the gaster

We analyze theoretically the moment of inertia of the desert ant Cataglyphis (C. bicolor and C. fortis) around a vertical axis through its own center of mass when the animal raises its gaster to a vertical position. Compared to the value when the gaster is horizontal, the moment of inertia is reduced to one half; this implies that when increasing its angular acceleration the ant need apply only half the level of torque when the gaster is raised, compared to when the gaster is lowered. As an example, we analyze the cases of an ant running on circular and sinusoidal paths. In both cases, the ant must apply a sideways thrust, anti-roll and anti-pitch torques to avoid toppling, and, on the circular path when accelerating and throughout the sinusoidal trajectory, a torque to enable turning as the path curves. When the ant is accelerating in a very tight circle or running on a very narrow sinusoidal path, in which the amplitude of the sinusoid is less than the length of the ant's body, the forces required for the turning torque can equal and exceed those required for the sideways thrust, and can be reduced significantly by the ant raising the gaster, whereas the foot-thrust for the anti-roll and anti-pitch torques rises only modestly when the gaster is up. This suggests that there may be an evolutionary advantage for employing the gaster-raising mode of locomotion, since this habit will allow desert ants to use lower forces and less energy, and perhaps run faster on more tortuous paths.     

NMR investigation of DNA primer-template models: structural insights into dislocation mutagenesis in DNA replication

Slipped frameshift intermediates can occur when DNA polymerase slows or stalls at sites of DNA lesions. However, this phenomenon is much less common when unmodified DNA is replicated. In order to study the effect of templating bases on the alignment of primer-templates, NMR structural investigation has been performed on primer-template oligonucleotide models which mimic the situation that dNTP has just been incorporated opposite template. NMR evidence reveals the occurrence of misalignment when dGTP is incorporated opposite template T with a downstream nucleotide C. Depending on the template sequence, further extension of the primer can lead to realignment.     

Pathogen clumping: an explanation for non-linear transmission of an insect virus

Abstract.  1. Previous work has shown that transmission of some insect pathogens is a non-linear process. A number of hypotheses have been put forward as explanations for this phenomenon; however, none have proven wholly satisfactory. Here we test the effects on transmission of spatial distribution of an insect virus by testing whether or not experimental manipulations of pathogen clumping lead to different values of a clumping parameter. The gypsy moth nucleopolyhedrovirus (LdMNPV) was used, which is transmitted when larvae consume virus released from previously infected larvae that have died on foliage.
2. It was found that even when virus densities on foliage were equal, overall mortality was lower when virus-killed cadavers were clumped on foliage.
3. Non-linearity is more pronounced when cadavers are clumped than when they are placed at random on the foliage. Placement of droplets containing LdMNPV on foliage resulted in more linear transmission compared with cadavers.
4. Spatial clumping of viral inoculum thus provides part of the explanation for non-linear transmission in this system. The ultimate explanation for non-linear transmission is likely to involve some combination of spatial clumping and heterogeneity in behaviours such as feeding rate or the ability to avoid pathogen.     

Varied-mapping conjunction search: evidence for rule-based learning

Five experiments were carried out to examine whether top-down processes can aid search, even when targets and distractors are variably mapped. Experiments 1a and 1b determined that effortless VM search can be obtained in Contrast Polarity X Orientation and Color X Orientation conjunction search when one feature dimension remains consistently mapped across blocks. Experiment 2 showed that efficient VM search is possible when both dimensions are variably mapped. In Experiment 3, efficient VM search was found when target-distractor reversals occurred on a trial-wise basis. Experiments 4 and 5 found that VM search deteriorates when target identity is not known prior to display onset. These studies demonstrate the role of top-down mechanisms in the development of efficient VM search and present several challenges to strength-theoretic views on the mechanisms underlying automaticity.     

Evidence of Public Engagement with Science: Visitor Learning at a Zoo-Housed Primate Research Centre

Primate behavioural and cognitive research is increasingly conducted on direct public view in zoo settings. The potential of such facilities for public engagement with science is often heralded, but evidence of tangible, positive effects on public understanding is rare. Here, the effect of a new zoo-based primate research centre on visitor behaviour, learning and attitudes was assessed using a quasi-experimental design. Zoo visitors approached the primate research centre more often when a scientist was present and working with the primates, and reported greater awareness of primates (including conservation) compared to when the scientist was not present. Visitors also reported greater perceived learning when the scientist was present. Installation of information signage had no main effect on visitor attitudes or learning. Visitors who interacted with the signage, however, demonstrated increased knowledge and understanding when asked about the specific information present on the signs (which was related to the ongoing facial expression research at the research centre). The findings show that primate behaviour research centres on public view can have a demonstrable and beneficial effect on public understanding of science.     

Kin-biased dispersal behaviour in the mango shield scale, Milviscutulus mangiferae

When fitness decreases with increasing density in a habitat, dispersal behaviour is expected to evolve. To avoid competition between kin, dispersal behaviour based on kin recognition should be more likely to occur when the individuals in a habitat are closely related. I tested this prediction with first-instar larvae (crawlers) of the mango shield scale, Milviscutulus mangiferae. The body size of adult females, a measure of fecundity, was larger when only one female was present on a leaf than when two were present. When I placed two crawlers on a leaf, they emigrated more frequently when they were siblings than when they were not related. I discuss the implication of the results for kin recognition in thelytokous parthenogenetic animals. Copyright 2000 The Association for the Study of Animal Behaviour.     

Facultative parthenogenesis and sex-ratio evolution

Summary Phenotypic models of selection are used to determine the effect of facultative parthenogenesis on the production of males in a spatially variable environment when (i) sex determination is under strict genetic control, and (ii) when sex may be environmentally determined. The results show that when sex is under strict genetic control and there is some chance of maturing in isolation, selection favors a female-biased sex ratio. When sex can be environmentally induced by cues which indicate high density, selection favors a mixture of genetic and environmental control, such that half the individuals always become female and the other half become females when isolated and become males when not isolated.     

Effect of mutation on genetic differentiation among nonequilibrium populations

The usefulness of GST and similar measures of genetic differentiation has been questioned repeatedly because of their dependence on the amount of heterozygosity within populations, creating problems when comparing degrees of divergence at loci with different mutation rates. Although the effect of mutation on GST is expected to be small in the early phases of divergence, it is unclear for how long after separation from a common ancestral population that GST is largely unaffected by mutation and by the resulting effect on heterozygosity. We address this question through analysis of the recursion equations for gene identity under the infinite allele model of mutation, and derive conditions describing when the effect of mutation on GST can be ignored under mutation-migration-drift equilibrium conditions and during the preceding transition phase. An important result is that during the transition phase GST is not only affected by mutation, but also by the heterozygosity in the base population from which the subpopulations diverged. The effect of mutation on GST is significant from the very start of the divergence process when initial heterozygosity is low, whereas GST is only weakly affected by mutation in the early phases of differentiation when initial heterozygosity is high. Thus, differentiation following a severe bottleneck is strongly dependent on mutation. The standardized measure of differentiation, G'ST, suggested by Hedrick (2005), may be helpful when comparing amounts of divergence at loci with different mutation rates under steady-state conditions, provided that migration is very low. In many other situations the use of G'ST might be misleading, however, and its application should be exercised with caution.     

The relative advantages of plasticity and fixity in different environments: when is it good for a plant to adjust?

Plant populations and species differ greatly in phenotypic plasticity. This could be because plasticity is advantageous under some conditions and disadvantageous or not advantageous under others. We distinguish adaptive from injurious and neutral plasticity and discuss when selection should favor adaptive plasticity over genetic differentiation or lack of phenotypic variation. It seems reasonable to hypothesize that selection is likely to favor plasticity when an environmental factor varies on the same spatial scale as the plant response unit, when the plant can respond to an environmental factor faster than the level of the factor changes, and when environmental variation is highly but not completely predictable. Phenotypic plasticity might also tend to be more advantageous when mean resource availability is high rather than low, when a response can occur late in development rather than early, and when a response is reversible rather than irreversible. There is substantial evidence for the hypothesis that predictability favors plasticity. However, available evidence does not support the hypothesis that high mean resource availability necessarily favors plasticity. Testing hypotheses about when it is good for a plant to adjust is central to understanding the diversity of plasticity in plants.     

The autumn and spring emigrations of juvenile Atlantic salmon, Salmo salar L., from the Girnock Burn, Aberdeenshire, Scotland: environmental release of migration

Peaks in the emigratory activity of sexually immature, juvenile Atlantic salmon, Salmo salar , occur in autumn and early winter and in spring at the Girnock Burn in Aberdeenshire. Stream temperature is apparently without effect on the release of potentially emigrant fish from the stream. Migrants tend to leave the stream when stream discharge rate is elevated. Whereas downstream movements in autumn and the earlier part of the spring are made almost invariably when the stream's discharge rate is higher than the seasonal norm, later in spring they often occur when discharge rates are lower than the seasonal norm and when no apparent increase in absolute stream discharge rate has occurred. Emigration is depressed in the lunar quarter centred on the full moon. The nature of the relationship between the autumn and spring emigrations is discussed.