bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resource dynamics and plant growth: a self‐assembling model for individuals, populations and communities
Authors: COLASANTI R. L. , HUNT R. 
Published: December 2004

1. We describe a new model of plant growth that is general, deterministic, non‐stationary and mechanistic in nature. Its purpose is to investigate the extent to which the morphology and function of the whole plant can be determined by resource acquisition and utilization on the part of its components. 2. The model is a two‐dimensional section, showing the plant in its above‐ and below‐ground environments. The whole plant is represented by a branching structure made up from standard ‘modules’. The behaviour of the complete plant is determined exclusively by a rule set that acts only at the level of the individual module. 3. At the level of the whole plant, the model displays a classic S‐shaped growth curve, plasticity in root–shoot allocation, and foraging in heterogeneous environments. 4. At the level of the plant population, the model exhibits self‐thinning along a –2/1 self‐thinning line. This accords with the behaviour expected of a two‐dimensional system and also adds weight to the ‘geometric’ interpretation of the –3/2 self‐thinning line commonly seen in crowded populations of real plants. 5. An imposed ‘mutation’ in one of the modular rules allows us to produce a modified plant type that displays active foraging. In a set of simulations involving a model community containing both the modified and standard plant types, the modified type predominates in resource‐rich environments, and vice versa. 6. The simulations demonstrate the effectiveness of modular rule‐based methods from which whole‐plant behaviour can arise as an emergent property. The model suggests that active foraging carries a cost that cannot satisfactorily be borne at low levels of resource availability. It also implies that competition for resources, both above and below ground is in the form of a ‘contest’ (rather than a ‘scramble’). The success of the modular model highlights the primacy of resource acquisition and utilization in determining the ecological status of the plant.
Questions and answers to psychological assessment schedules: hidden troubles in ‘quality of life’ interviews
Authors: Antaki C. , Rapley M. 
Published: December 2004

AbstractQuality of life (QOL) has become a topic of much debate in the learning difficulties literature. Increasing use is made of questionnaire‐driven interview schedules in an effort to find out v/hat clients believe in their own words. However, in this paper, the authors argue that the use made of such questionnaires may actually distort interviewees ‘own words’ by severely underestimating the degree to which the questions and answers are changed by the subtle dynamics of the interview. In the first ever close examination of what actually happens in a QOL assessment interview, the qualitative insights of conversation analysis are used to show that the typical administration of a well‐known instrument will involve: (1) distortions of the questions brought about by the need to paraphrase complex items, and the inevitable use of pre‐questions and response listing; and perhaps more disturbingly, (2) distortions of answers brought about by interviewers’pursuit of legitimate answers and non‐take‐up of interviewees’ matters. The authors believe that these difficulties make it hard for researchers to draw conclusions from simple aggregation of recorded responses to this questionnaire, and, perhaps, to any questionnaire using a fixed‐response schedule. On the other hand, the kind of close evidence used here may allow inferences to be drawn about clients’ feelings of well being, but even so, these will need to be cast in terms which acknowledge the interactive and constructive nature of feeling‐avowals.
Schizophrenia in people with intellectual disability: the role of pregnancy and birth complications
Authors: O'Dwyer J. M. 
Published: December 2004

AbstractThe literature suggests that mental illness is more common in people with intellectual disability than in the general population. Having reviewed the literature, Turner (1989)[Psychological Medicine19, 301–14] suggested that about 3% of people with intellectual disability also have schizophrenia. As pregnancy and birth complications (PBCs) occur more commonly in people with intellectual disability than in the general population and are also implicated in the aetiology of schizophrenia, it is possible that these conditions share a common aetiology. This study reports on the occurrence of PBCs in those people with intellectual disability who develop schizophrenia. Fifty people with intellectual disability and schizophrenia were matched for age, sex, degree of intellectual disability and presence of epilepsy with a control group who did not suffer from schizophrenia or a schizophreniform psychosis. The obstetric history was obtained and events rated on a scale specifically designed for this study. This PBCs scale consists of six sub‐scales covering areas of general maternal health, pregnancy, delivery, medication in labour, total medication score and neonatal score, as well as an overall total score. The study found that people with intellectual disability who develop schizophrenia have significantly higher rates of PBCs than controls. All of the sub‐scales on the PBCs scale were significantly higher in people with schizophrenia, with the exception of the medication scales. Only five out of the 50 people with schizophrenia had not had a major obstetric complication, compared to 13 subjects from the control group. A number of abnormalities were specifically higher in people who later developed schizophrenia. These included: abnormally long or short labour; maternal episiotomy; maternal preeclamptic toxaemia; induction of labour; dysmaturity; maternal smoking in pregnancy; and a delay in neonatal crying. The results suggest that PBCs are important in the aetiology of schizophrenia in people with intellectual disability.
Sexual abuse perpetrated by men with intellectual disabilities: a comparative study
Authors: Brown H. , Stein J. 
Published: December 2004

AbstractThis paper compares cases of sexual abuse of adults with intellectual disabilities, reported across the South East of England, which were perpetrated by men with intellectual disabilities, with those committed by other male perpetrators. The comparison provides some support for the findings of other studies, which have suggested that men with intellectual disabilities offend against more male victims than non‐disabled sex offenders and that their offences are somewhat less serious, but otherwise indicates common patterns of abusive behaviour across this divide but differential service responses and support for victims. So called ‘peer abuse’ is a widespread problem which service agencies have failed to address: repeated offences are frequent and lack of appropriate intervention is the norm.
Monday and non‐Monday concentrations of lifestyle‐related blood components in the Oslo Diet and Exercise Study
Authors: Urdal P. , Anderssen S. A. , Holme I. , Hjermann I. , Mundal H. H , Haaland A. , Torjesen P. 
Published: December 2004

Urdal P, Anderssen SA, Holme I, Hjermann I, Mundal HH, Haaland A, Torjesen P (Ullevål University Hospital; Norwegian University of Sport and Physical Education; and Aker University Hospital, Oslo, Norway). Monday and non‐Monday concentrations of lifestyle‐related blood components in the Oslo Diet and Exercise Study. J Intern Med 1998; 244: 507–13.Objective We hypothesized that participants of intervention studies have an unfavourable lifestyle at the weekend compared with the rest of the week, thus affecting the concentrations of components in samples drawn on Mondays.Design The hypothesis was examined using data from the Oslo Diet and Exercise Study, a 2 × 2 randomized intervention trial on diet and exercise involving 209 participants. Each person chose which day of the week to attend for blood sampling, both before and after the 1 year of intervention.Main outcome measures Comparison of mean concentrations of the components measured, in samples drawn on Mondays vs. non‐Mondays, both at the start and at the end of intervention.Results At the start, nine components, from haemostasis, carbohydrate and lipid metabolism, showed a difference of more than 10% between Monday and non‐Monday values, all Monday values differing from the non‐Monday values in a cardiovascularly unfavourable direction. Participants starting and ending on a Monday showed the unfavourable profile both times, and those who were examined both times on a non‐Monday showed a consistently favourable profile, whereas those who changed the day of examination at the start and end changed profile accordingly.Conclusion The lifestyle‐related components examined here showed differences between Monday and non‐Monday values, which were not due to a selection bias. We suggest they may be related to a different lifestyle at the weekend compared with ordinary working days. If such effects are not recognized and properly taken into account, they may markedly affect the outcome of intervention studies.
Continuous ST‐segment monitoring of patients with left bundle branch block and suspicion of acute myocardial infarction
Authors: Gunnarsson G. , Eriksson P. , Dellborg M. 
Published: December 2004

Abstract.Objectives.  Patients with left bundle branch block comprise 5–9% of all patients with acute myocardial infarction. Limited data exist on the usefulness of continuous electrocardiographic monitoring of these patients. We have investigated prospectively the usefulness of real‐time continuous vectorcardiography for monitoring patients with left bundle branch block and suspicion of acute myocardial infarction.Design.  A prospective multi‐centre study.Setting.  Fourteen Swedish coronary care units.Subjects.  Patients with left bundle branch block and suspicion of acute myocardial infarction with <6‐h symptom duration were included.Main outcome measures.  All patients were monitored with continuous vectorcardiography for 12–24 h.Results.  One hundred thirty‐three patients were included, 47% had acute myocardial infarction. Patients with acute myocardial infarction showed a marked relative decrease in ST‐vector than those without (P = 0.0002). These changes were most marked in the first 90 min. When comparing patients with acute myocardial infarction receiving thrombolytic therapy or not, those treated with thrombolytics showed more marked decline in ST‐vector magnitude (P < 0.0001) and in shorter time (P = 0.0017). All patients showed STC‐vector magnitude changes that were more marked in patients with acute myocardial infarction (P = 0.0002). An STC‐vector magnitude cut‐off value of 65 μV after 90 min of monitoring gave 54% sensitivity and 72% specificity for diagnosis of acute myocardial infarction.Conclusion.  Real‐time continuous vectorcardiographic monitoring of patients with left bundle branch and suspicion of acute myocardial infarction shows significant differences between those with and without acute myocardial infarction and could be of use for early diagnosis and subsequent monitoring.
The genetics of phenotypic plasticity. II. Response to selection
Authors: Scheiner Samuel M. , Lyman Richard F. 
Published: December 2004

AbstractWe selected on phenotypic plasticity of thorax size in response to temperature in Drosophila melanogaster using a family selection scheme. The results were compared to those of lines selected directly on thorax size. We found that the plasticity of a character does respond to selection and this response is partially independent of the response to selection on the mean of the character. One puzzling result was that a selection limit of zero plasticity was reached in the lines selected for decreased plasticity yet additive genetic variation for plasticity still existed in the lines. We tested the predictions of three models of the genetic basis of phenotypic plasticity: overdominance, pleiotropy, and epistasis. The results mostly support the epistasis model, that the plasticity of a character is determined by separate loci from those determining the mean of the character.
Phylogenetic analysis and the evolution of queen number in eusocial Hymenoptera
Authors: Ross Kenneth G. , Carpenter James M. 
Published: December 2004

AbstractAnalyses of the evolution of colony queen number in eusocial insects have generally been conducted without specific reference to phylogenetic relationships, leading to incomplete evolutionary explanations for this key attribute of social organization. Consideration of queen number in a phylogenetic context in the highly eusocial Hymenoptera reveals that its evolution has been very conservative in the bees but that it is a highly labile character in most ants. The wasps appear intermediate in this respect, with some large and widespread clades characterized by little or no phylogenetic variability in queen number. This hierarchy of phylogenetic lability suggests that while ant populations may often be responsive to selection on colony queen number linked with local ecology, bees and wasps appear less responsive in this regard, with a significant element of phylogenetic conservatism involved in the expression of this social trait in the latter two groups.
Parental effects in Lychnis flos‐cuculi. II: Selection on time of emergence and seedling performance in the field
Authors: Biere A. 
Published: December 2004

AbstractSelection on the timing of seedling emergence was investigated in an experimental population of Lychnis flos‐cuculi, a perennial hay‐meadow species. Seeds obtained from a full diallel cross of 8 genotypes from a field population were sown along an environment gradient that included the parental site.Significant directional selection for early emergence was found and the intensity of selection varied among sites. Emergence time varied significantly among progeny families of different maternal and paternal genotypes. These differences could be attributed to parental effects whereas narrow‐sense heritabilities were close to zero. Survivorship until autumn differed among progeny of paternal families. Survivorship of maternal progeny varied among sites. Whereas differences in survival and plant size among individuals from different emergence cohorts persisted over the winter, the significance of these differences among progeny from different parental genotypes disappeared.It is suggested that a response to selection on emergence time might be low since (1) the narrow sense heritability was low, (2) parental genotypes differed in their effect on offspring emergence time when used as female parent or as pollen donor and (3) there was a family x site interaction for survival. Families with relatively early emerging seedlings also had a significantly higher seed weight, emergence percentage, and plant weight although the strength of these among‐family correlations varied among sites. It is therefore not likely that simultaneous selection on emergence time and either of these traits would retard a response to selection on emergence time.
The heritability of sexually dimorphic traits in the yellow dung fly Scathophaga stercoraria (L.)
Authors: Simmons Leigh W. , Ward Paul I. 
Published: December 2004

AbstractA precise method was used for estimating the proportion of heritable variation in two life history parameters of the yellow dung fly, whereby environmental components of variance were minimized. Significant heritable variation for body size was revealed for father to son and mother to daughter relationships. Variation in development time was not significantly heritable. There is a marked sexual dimorphism in body size in this species which is discussed in the light of the observed sex‐genotype interaction in heritabilities and low genetic correlation for size between the sexes. It is suggested that opposing pressures of sexual and natural selection and/or genetic pleotropy may be responsible for the maintenance of heritable variation, and the evolution of sexual dimorphism in these two traits.
Experimental study of temperature effects on the sex ratio of broods in Terrestrial Crustacea Armadillidium vulgare Latr. Possible implications in natural populations
Authors: Rigaud T. , Juchault P. , Mocquard J. P. 
Published: December 2004

AbstractThe woodlouse Armadillidium vulgare is characterized by female heterogamety (ZW) and male homogamety (ZZ). However, in several populations, sex determination is influenced by cytoplasmic sex factors (endosymbiotic bacteria = F). At 20 °C these maternally transmitted bacteria reverse genetic males into functional neo‐females (ZZ + F) producing highly female broods.When these neo‐females were reared at 30° C, the sex ratio of their broods became male‐biased. The major process involved in this heat‐induced sex ratio inversion was the disappearance of bacteria in embryos in the course of their development, which allowed the young to express a phenotype that conforms with their genotype (i.e. male ZZ). No heat‐sensitive stage of development was observed, but at least 35 days at 30° C seem to be necessary to induce F‐degradation. The presence of F at 30° C (before its degradation) also induced mortality during vitellogenesis.Daily thermoperiods including a thermophase at 30° C had effects on F similar to that of a constant temperature of 30° C. A. vulgare can live in climates having such thermoperiods (at least during one period of the year), temperature appears to be capable of limiting the presence of F‐bacteria in natural populations, and then modifying the evolution of sex‐determining mechanisms in such populations.
Limits to runaway sexual selection: The wallflower paradox
Authors: De Jong Mart C. M. , Sabelis Maurice W. 
Published: December 2004

AbstractIn his mathematical treatment of Fisher's ideas on sexual selection (so‐called runaway selection) Lande (1981) predicted that males may evolve increasingly elaborate sexual characters despite opposing viability selection as a consequence of the associated costs.Lande thereby assumed that female mate preferences are not subject to selection since (1) females are all inseminated and (2) the quantity and quality of their offspring are independent of the female's mate preferences. Kirkpatrick (1985) removed the latter assumption and investigated the consequences for the mean phenotype with respect to both female and male traits. He also explored the dynamics of the (co)‐variance matrix by numerical methods.In this paper we consider a simpler model with just two multi‐allelic loci. This enables us to derive explicit expressions for (co)‐variances under steady state conditions. Rather than assume natural selection through differential fertility (as in Kirkpatrick, 1985), we take sexual selection on females into account by modelling the preference‐dependent risk that females remain unmated.We argue that this wallflower effect is a realistic feature of any mating system, since it merely depends on the existence of (1) variation in mating preferences and (2) a finite mating season. Our approach provided an insight into the dynamic behaviour of the means of the phenotypes. This is because the dynamics of the means depend on the steady state (co)‐variance matrix. Thus, an insight into the former requires explicit expressions for the latter.Whereas Lande and Kirkpatrick predicted runaway processes, despite opposing viability selection, our model predicts a globally stable steady state, i.e. no runaway, even without opposing viability selection (under the assumption of an asymptotically stable steady state of the (co)‐variances. Admittedly, we have no analytic proof of this stability but only support for it, based on simulations.) The absence of the runaway processes in our model is caused by the wallflower effect, since it imposes constraints on the steady state of the (co)‐variance matrix.When mutational input applies to female traits but not to male traits, explicit expressions for the (co)‐variances under steady state conditions can be derived, and these show that: (1) both the genetic covariance and the variance of male traits are equal to zero, but (2) the variance of the female trait exceeds to zero. Should there be mutational input influencing the male trait, then these results would suggest that the male‐to‐female ratio of variances is much smaller than unity. This prediction is of tremendous importance for speciation through founding events.
Sex allocation in an hermaphroditic plant: the case of gynodioecy in Thymus vulgaris L.
Authors: Atlan A. , Gouyon P. H. , Fournial T. , Pomente D. , Couvet D. 
Published: December 2004

AbstractResource allocation to male and female functions was investigated in Thymus vulgaris L. (thyme), a gynodioecious species, in which females produce twice as many seeds as hermaphrodites. Negative correlations were found between male and female fertility of hermaphrodites, providing evidence of a trade‐off. There was a high variability in sexual investment, some of the hermaphrodites functioning almost as males, and others almost as females. Estimation of the relative cost of male and female gametes showed that the female advantage in seed production was mainly due to reallocation of the resources not allocated to male function into female function. The determination of sex allocation was shown to have a genetic component, and there were some evidence that an interaction between nuclear and cytoplasmic genomes was involved.
The genetic basis and evolution of acoustic mate recognition signals in a Ribautodelphax planthopper (Homoptera, Delphacidae) 1. The female call
Authors: De Winter A. J. 
Published: December 2004

AbstractBoth sexes of the planthopper Ribautodelphax imitans produce species specific acoustic signals. Earlier experiments have shown that isolation between Ribautodelphax species in captivity is at least partly due to male preference for calls of conspecific females. The genetic basis of the female call is studied by bi‐directional artificial selection for large and small interpulse intervals (IPI). This resulted in non‐overlapping distributions of IPI after only five generations. The mean of eight realized heritability estimates over five generations was above 80%; estimates over ten generations were generally well above 50%. The character is shown to be of a polygenic nature, determined by at least 6 segregating genetic factors. The other features of the female call, strophe duration, and modulation of pulse repetition frequency within the strophe, showed significantly correlated responses. Sexual isolation tests after 10 generations of selection revealed significant symmetrical assortative mating, but coselected males did not exhibit a significant preference for playback calls of females from their own selection line. In view of the high heritability for the call character, and the considerable ecological isolation among Ribautodelphax species, it seems unlikely that the female call differentiated as an adaptation to prevent hybridization (reinforcement). More likely, call and call preference were shaped by sexual selection during allopatry, and may have (had) incidentally an effect in species isolation.