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Co-occurrence
Kinds of Co-occurrence Terms modified by Co-occurrence Selected AbstractsCo-ocurrence of developmental delays in a screening study of 4-year-old Finnish childrenDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 7 2004Riitta Valtonen The aim of this population study was to examine the severity and prevalence of co-occurring developmental delays in 4-year-old children, the rate of overlapping problems, and sex differences. A sample of 434 children (196 males, 238 females; mean age 4 years 3 months, SD 1 month) were administered the,Lene'test: a comprehensive neuro-developmental screening test. Results suggest that co-occurrence of attention-behavioural, motor-perceptual, and language delays occurring in school-aged children could already be detected at the age of 4 years. Isolated delays were usually mild, but co-occurring difficulties were mostly moderate or severe. Overlap between developmental delays depended on the severity of the problems. It emerged that males had more severe and more often co-occurring problems than females. Co-occurrence of developmental delays as a risk factor at the early stage of development is discussed. [source] Co-occurrence of ectoparasites of marine fishes: a null model analysisECOLOGY LETTERS, Issue 1 2002Nicholas J. Gotelli We used null model analysis to test for nonrandomness in the structure of metazoan ectoparasite communities of 45 species of marine fish. Host species consistently supported fewer parasite species combinations than expected by chance, even in analyses that incorporated empty sites. However, for most analyses, the null hypothesis was not rejected, and co-occurrence patterns could not be distinguished from those that might arise by random colonization and extinction. We compared our results to analyses of presence,absence matrices for vertebrate taxa, and found support for the hypothesis that there is an ecological continuum of community organization. Presence,absence matrices for small-bodied taxa with low vagility and/or small populations (marine ectoparasites, herps) were mostly random, whereas presence,absence matrices for large-bodied taxa with high vagility and/or large populations (birds, mammals) were highly structured. Metazoan ectoparasites of marine fishes fall near the low end of this continuum, with little evidence for nonrandom species co-occurrence patterns. [source] Co-occurrence of the ascomycete Lophodermium piceae and the rust fungus Chrysomyxa abietis in Norway spruce needlesFOREST PATHOLOGY, Issue 1 2001A. Lehtijärvi The frequency of needles and the proportion of needle segments infected by Lophodermium piceae were compared in symptomless and Chrysomyxa abietis- infected, 1-year-old needles of Picea abies. In late spring, symptomless needles from both rust-infected and healthy saplings were sampled. In addition, rust-infected, totally chlorotic needles and needles with chlorosis along about half their length from the diseased trees were examined. In all three stands, the proportion of segments infected by L. piceae was larger in the rust-infected half of the needle than in the symptomless half; but the difference was statistically significant in only one of the stands. The proportion of L. piceae -infected segments among the nonrust-infected needles was the same as that found for the uninfected half of rust-infected needles (after correction for size differences). No differences in the proportion of L. piceae -infected segments were found between the totally chlorotic, rust-infected needles and the green needles of diseased or healthy trees. [source] Co-occurrence of posttraumatic stress disorder with positive psychotic symptoms in a nationally representative sampleJOURNAL OF TRAUMATIC STRESS, Issue 4 2005Jitender Sareen The association between posttraumatic stress disorder (PTSD) and positive psychotic symptoms was examined in the National Comorbidity Survey (N = 5877). The Composite International Diagnostic Interview (CIDI) was used to make DSM-III-R (Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised; American Psychiatric Association, 1987) diagnoses. Posttraumatic stress disorder was found to be associated with an increased likelihood of endorsing one or more psychotic symptoms after adjusting for sociodemographics, psychiatric and medical comorbidity (odds ratios (OR) = 1.83; 95% confidence interval (CI): 1.43,2.45; p < .001). The co-occurrence of PTSD with psychotic symptoms was marked by greater levels of severity (higher total number of PTSD symptoms, greater levels of comorbidity, and high distress) compared with PTSD alone. This is the first population-based study to investigate PTSD in relation to endorsement of positive psychotic symptoms, and a strong association was obtained. [source] Co-occurrence in nature of different clones of the social amoeba, Dictyostelium discoideumMOLECULAR ECOLOGY, Issue 4 2003A. Fortunato Abstract The social amoeba, Dictyostelium discoideum, produces a multicellular fruiting body and has become a model system for cell,cell interactions such as signalling, adhesion and development. However, unlike most multicellular organisms, it forms by aggregation of cells and, in the laboratory, forms genetic chimeras where there may be competition among clones. Here we show that chimera formation is also likely in nature, because different clones commonly co-occur on a very small scale. This suggests that D. discoideum will likely have evolved strategies for competing in chimeras, and that the function of some developmental genes will be competitive. Natural chimerism also makes D. discoideum a good model organism for the investigation of issues relating to coexistence and conflict between cells. [source] Co-occurrence of ectoparasites on rodent hosts: null model analyses of data from three continentsOIKOS, Issue 1 2010Boris R. Krasnov We studied patterns of species co-occurrence in communities of ectoparasitic arthropods (ixodid ticks, mesostigmate mites and fleas) harboured by rodent hosts from South Africa (Rhabdomys pumilio), South America (Scapteromys aquaticus and Oxymycterus rufus) and west Siberia (Apodemus agrarius, Microtus gregalis, Microtus oeconomus and Myodes rutilus) using null models. We compared frequencies of co-occurrences of parasite species or higher taxa across host individuals with those expected by chance. When non-randomness of parasite co-occurrences was detected, positive but not negative co-occurrences of parasite species or higher taxa prevailed (except for a single sample of mesostigmate mites from O. rufus). Frequency of detection of non-randomness of parasite co-occurrences differed among parasite taxa, being higher in fleas and lower in mites and ticks. This frequency differed also among host species independent of parasite taxon, being highest in Microtus species and lowest in O. rufus and S. aquaticus. We concluded that the pattern of species co-occurrence in ectoparasite communities on rodent hosts is predominantly positive, depends on life history of parasites and may be affected to a great extent by life history of a host. [source] Association of Extraesophageal Reflux Disease and Sinonasal Symptoms: Prevalence and Impact on Quality of Life,THE LARYNGOSCOPE, Issue 12 2007Thomas R. Pasic MD Abstract Objectives: The purpose of this study was to investigate the prevalence of extraesophageal reflux disease symptoms and their association with sinonasal disorders within a general sample of adults in our community and to determine how these conditions affect perception of general health, sinus-related quality of life (QOL), and perception of reflux and digestive function. Study Design/Methods: A community-dwelling sample of 1,878 adults completed symptom and QOL surveys in a two-stage prospective design: an initial screening questionnaire (n = 1,878) and disease-specific (sinus and reflux/digestion) and general health-related QOL instruments (n = 1,073). Demographic and response data were summarized and analyzed for prevalence and correlations among data sets. Results: Sinonasal symptoms were reported in 71% of subjects who completed the initial screening questionnaire, and reflux-related symptoms were reported by 59% of respondents. The co-occurrence of sinonasal and reflux symptoms was reported by 45% of respondents. Subjects with both sinonasal and reflux symptoms scored significantly worse on the disease-specific and general physical and mental QOL scales than subjects with only reflux or sinonasal symptoms or no symptoms. Conclusions: Symptoms associated with inflammatory sinonasal disorders and gastroesophageal reflux disease are common in the general U.S. adult population and co-occur in the same individuals to a greater degree than can be attributed to chance alone. Co-occurrence was found to be associated with significant declines in both disease-specific and general physical and mental QOL. This finding has implications with regard to pathogenesis and treatment of these disorders. [source] Crunoecia irrorata (Curtis) (Trichoptera: Lepidostomatidae) and conservation of boreal springs: indications of clustering of red-listed speciesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2008Jari Ilmonen Abstract 1.Crunoecia irrorata is widely dispersed across Europe, but rare and red-listed in Finland. Its geographical range comprises most of the southern boreal zone in Fennoscandia. The species is confined to springs in the north, but occurs also in lower reaches of headwater streams in central and western Europe. It becomes more rare and less abundant towards the limits of its range across Europe, showing diffusive rarity. Glacial history and climate limit the distribution of the species in the north. 2.The most important habitat characteristic for C. irrorata in Finland was the total area of helocrene habitats. Its occurrence was positively related to taxon richness of benthic macroinvertebrates, but not bryophytes. Co-occurrence of C. irrorata with other red-listed spring-dependent taxa was observed, indicating high conservation value of the springs occupied. 3.Crunoecia irrorata occurred frequently in moderately disturbed springs, indicating tolerance to human disturbance around springs. However, the effect of the disturbance on population size is not known. Forestry and water and gravel extraction are potential threats to C. irrorata, and only a few of its populations are strictly protected. Therefore, populations of C. irrorata in the boreal zone should be conserved and monitored to ensure the species' survival at the northern limits of its range. Copyright © 2007 John Wiley & Sons, Ltd. [source] EXAMINING THE "CRIMINAL CAREERS" OF PROSTITUTES WITHIN THE NEXUS OF DRUG USE, DRUG SELLING, AND OTHER ILLICIT ACTIVITIES,CRIMINOLOGY, Issue 3 2000SHEILA ROYO MAXWELL This paper examines the co-occurrence of prostitution, drug use, drug selling, and involvement in non-drug crimes among women who have used serious drugs (e.g., crack, heroin). Existing perspectives on the drug use-prostitution nexus are re-examined using three dimensions of the criminal career paradigm: prevalence, lambda, and age of onset. Results show that approximately one-half of the women who reported regular drug use never prostituted, and that, except for use of crack cocaine, use of other drugs was unrelated to the prevalence, frequency, or age of onset into prostitution. The results also show that committing property crime was associated with an increased prevalence and early onset into prostitution, while selling drugs coincided with a decreased prevalence and delayed onset into prostitution. [source] Co-ocurrence of developmental delays in a screening study of 4-year-old Finnish childrenDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 7 2004Riitta Valtonen The aim of this population study was to examine the severity and prevalence of co-occurring developmental delays in 4-year-old children, the rate of overlapping problems, and sex differences. A sample of 434 children (196 males, 238 females; mean age 4 years 3 months, SD 1 month) were administered the,Lene'test: a comprehensive neuro-developmental screening test. Results suggest that co-occurrence of attention-behavioural, motor-perceptual, and language delays occurring in school-aged children could already be detected at the age of 4 years. Isolated delays were usually mild, but co-occurring difficulties were mostly moderate or severe. Overlap between developmental delays depended on the severity of the problems. It emerged that males had more severe and more often co-occurring problems than females. Co-occurrence of developmental delays as a risk factor at the early stage of development is discussed. [source] Diabetes classification: grey zones, sound and smoke: Action LADA 1DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 7 2008R. D. G. Leslie Abstract Diseases gain identity from clinical phenotype as well as genetic and environmental aetiology. The definition of type 1 diabetes is clinically exclusive, comprising patients who are considered insulin dependent at diagnosis, whilst the definition of type 2 diabetes is inclusive, only excluding those who are initially insulin dependent. Ketosis-prone diabetes (KPD) and latent autoimmune diabetes in adults (LADA) are each exclusive forms of diabetes which are, at least initially, clinically distinct from type 2 diabetes and type 1 diabetes, and each have a different natural history from these major types of diabetes. KPD can be diagnosed unequivocally as diabetes presenting with the categorical clinical feature, ketoacidosis. In contrast, LADA can be diagnosed by the co-occurrence of three traits, not one of which is categorical or exclusive to the condition: adult-onset non-insulin-requiring diabetes, an islet autoantibody such as glutamic acid decarboxylase autoantibodies (GADA) or cytoplasmic islet cell autoantibodies (ICA), and no need for insulin treatment for several months post-diagnosis. But while some would split diabetes into distinct subtypes, there is a strong case that these subtypes form a continuum of varying severity of immune and metabolic dysfunction modified by genetic and non-genetic factors. This article discusses the nature of disease classification in general, and KPD and LADA in particular, emphasizing the potential value and pitfalls in classifying diabetes and suggesting a need for more research in this area. Copyright © 2008 John Wiley & Sons, Ltd. [source] Spatial and temporal organisation of the pre-dispersal seed predator guild in a perennial legume, Vicia tenuifoliaECOLOGICAL ENTOMOLOGY, Issue 2 2006Árpád Szentesi Abstract., 1. The variability of species combinations and membership assembly patterns in an insect pre-dispersal seed predator guild were studied at various spatial and temporal resolutions using presence/absence and abundance data in null models. The guild consists of seven beetle species (four bruchids and three curculionids) and one moth species that live on a perennial vetch, Vicia tenuifolia Roth (Leguminosae). 2. The seed predator guild varied considerably in the number of members and species combinations in space and time, and, contrary to expectations, there was no evidence of interspecific competition among guild members, supporting the view that other processes, including chance events, could contribute to guild formation. 3. It is concluded that, apart from the possibility of stochastic co-occurrence, it is the narrow host specialisation that constrains seed predator members to participate in the guild, and small differences in habitat preference can also lead to spatial and temporal variation. [source] Metacommunity patterns of highly diverse stream midges: gradients, chequerboards, and nestedness, or is there only randomness?ECOLOGICAL ENTOMOLOGY, Issue 5 2005Jani Heino Abstract., 1.,Several non-random patterns in the distribution of species have been observed, including Clementsian gradients, Gleasonian gradients, nestedness, chequerboards, and evenly spaced gradients. Few studies have examined these patterns simultaneously, although they have often been studied in isolation and contrasted with random distribution of species across sites. 2.,This study examined whether assemblages of chironomid midges exhibit any of the idealised distribution patterns as opposed to random distribution of species across sites within the metacommunity context in a boreal drainage system. Analyses were based on stream surveys conducted during three consecutive years. Analytical approaches included ordinations, cluster analysis, null models, and associated randomisation methods. 3.,Midge assemblages did not conform to Clementsian gradients, which was evidenced by the absence of clearly definable assemblage types with numerous species exclusive to each assemblage type. Rather, there were signs of continuous Gleasonian variability of assemblage composition, as well as significant nested subset patterns of species distribution. 4.,Midge assemblages showed only weak relationships with any of the measured environmental variables, and even these weak environmental relationships varied among years. 5.,Midge assemblages did not appear to be structured by competition. This finding was somewhat problematic, however, because the two indices measuring co-occurrence provided rather different signs of distribution patterns. This was probably a consequence of how they actually measure co-occurrence. 6.,Although midge assemblages did not show a perfect match with any of the idealised distribution patterns, they nevertheless showed a resemblance to the empirical patterns found previously for several plant and animal groups. [source] Stochastic and deterministic processes jointly structure tropical arthropod communitiesECOLOGY LETTERS, Issue 4 2009M. D. Farnon Ellwood Abstract The question of whether ecological assemblages are structured by stochastic and deterministic (e.g. interspecific competition) processes is controversial, but it is difficult to design sampling regimes and experiments that can dissect the relative importance of stochastic and deterministic processes in natural assemblages. Using null models, we tested communities of arthropod decomposers in tropical epiphytes for patterns of species co-occurrence, while controlling for habitat gradients, seasonal variations and ecological succession. When environmental conditions were controlled, our analysis showed that the communities were structured stochastically. However, analysing mixed sets of communities that were deliberately created either from two distinct heights or two successional stages revealed that communities were structured deterministically. These results confirm that habitat gradients and dispersal/competition trade-offs are capable of generating non-random patterns within decomposer arthropod communities, but reveal that when such effects are accounted for, species co-occurrence is fundamentally random. [source] Scale dependence of the correlation between human population presence and vertebrate and plant species richnessECOLOGY LETTERS, Issue 1 2007Marco Pautasso Abstract Human presence is generally negatively related to species richness locally, but the relationship is positive at coarse scales. An increase in the strength of the latter correlation with increasing study resolution has been documented within studies, but it is not known whether such a scale dependence is present across different studies. We test this with data on the spatial co-occurrence of human beings and the species richness of plants and vertebrates from a continuum of scales. The correlation coefficient between human presence and species richness is positively related to study grain and extent. The correlation turns from positive to negative below a study grain of c. 1 km and below a study extent of c. 10 000 km2. The broad-scale positive correlation between human presence and species richness suggests that people have preferentially settled and generally flourished in areas of high biodiversity and/or have contributed to it with species introductions and habitat diversification. The scale dependency of the correlation between people and biodiversity's presence emphasizes the importance of the preservation of green areas in densely populated regions. [source] Development of toxicity identification evaluation procedures for pyrethroid detection using esterase activityENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2004Craig E. Wheelock Abstract Recent agrochemical usage patterns suggest that the use of organophosphate (OP) pesticides will decrease, resulting in a concomitant increase in pyrethroid usage. Pyrethroids are known for their potential toxicity to aquatic invertebrates and many fish species. Current toxicity identification evaluation (TIE) techniques are able to detect OPs, but have not been optimized for pyrethroids. Organophosphate identification methods depend upon the use of piperonyl butoxide (PBO) to identify OP-induced toxicity. However, the use of PBO in TIE assays will be confounded by the co-occurrence of OPs and pyrethroids in receiving waters. It is necessary, therefore, to develop new TIE procedures for pyrethroids. This study evaluated the use of a pyrethroid-specific antibody, PBO, and carboxylesterase activity to identify pyrethroid toxicity in aquatic toxicity testing with Ceriodaphnia dubia. The antibody caused significant mortality to the C. dubia. Piperonyl butoxide synergized pyrethroid-associated toxicity, but this effect may be difficult to interpret in the presence of OPs and pyrethroids. Carboxylesterase activity removed pyrethroid-associated toxicity in a dose-dependent manner and did not compromise OP toxicity, suggesting that carboxylesterase treatment will not interfere with TIE OP detection methods. These results indicate that the addition of carboxylesterase to TIE procedures can be used to detect pyrethroids in aquatic samples. [source] Self-care versus self-harm: piercing, tattooing, and self-injuring in eating disordersEUROPEAN EATING DISORDERS REVIEW, Issue 1 2005Laurence Claes Abstract Eating disordered patients seem to have a love,hate relationship with their bodies. Why do some decorate their bodies by means of tattooing and piercing, while others deliberately injure themselves and make parts of their body unattractive? We have explored this question in 101 eating-disordered patients by means of self-reporting questionnaires about the presence and characteristics of tattooing, piercing and self-injuring as well as the underlying motives. Furthermore, we studied the co-occurrence of impulsive behaviours as well as personality traits. In our patient sample, 11.9,per,cent had one or more tattoos, 25.7,per,cent a piercing and 64.9,per,cent showed some form of self-injurious behaviour (SIB). Tattooing and piercing are clearly driven by esthetical reasons, whereas SIB can have various explanations. All three behaviours were significantly more often linked to substance (ab)use. With respect to personality traits, piercing was positively linked to extraversion (positive affectivity) and openness, and negatively to conscientiousness. SIB, on the contrary, was positively linked to neuroticism (negative affectivity) and conscientiousness, and negatively to extraversion and openness. Tattooing did not show significant correlations with particular personality traits (probably due to the small number of tattooed patients). In summary, piercing and tattooing seem to reflect more self-care, and might protect some patients against more self-harm. Copyright © 2005 John Wiley & Sons, Ltd and Eating Disorders Association. [source] QUANTITATIVE GENETICS OF SEXUAL PLASTICITY: THE ENVIRONMENTAL THRESHOLD MODEL AND GENOTYPE-BY-ENVIRONMENT INTERACTION FOR PHALLUS DEVELOPMENT IN THE SNAIL BULINUS TRUNCATUSEVOLUTION, Issue 5 2000Marie-France Ostrowski Abstract Sexual polymorphisms are model systems for analyzing the evolution of reproductive strategies. However, their plasticity and other binary traits have rarely been studied, with respect to environmental variables. A possible reason is that, although threshold models offer an adequate quantitative genetics framework for binary traits in a single environment, analyzing their plasticity requires more refined empirical and theoretical approaches. The statistical framework proposed here, based on the environmental threshold model (ETM), should partially fill this gap. This methodology is applied to an empirical dataset on a plastic sexual polymorphism, aphally, in the snail Bulinus truncatus. Aphally is characterized by the co-occurrence of regular hermaphrodites (euphallics) together with hermaphrodites deprived of the male copulatory organ (aphallics). Reaction norms were determined for 40 inbred lines, distributed at three temperatures, in a first experiment. A second experiment allowed us to rule out maternal effects. We confirmed the existence of high broad-sense heritabilities as well as a positive effect of high temperatures on aphally. However a significant genotype-by-environment interaction was detected for the first time, suggesting that sexual plasticity itself can respond to selection. A nested series of four ETM-like models was developed for estimating genetical effects on both mean aphally rate and plasticity. These models were tested using a maximum-likelihood procedure and fitted to aphally data. Although no perfect fit of models to data was observed, the refined versions of ETM models conveniently reduce the analysis of complex reaction norms of binary traits into standard quantitative genetics parameters, such as genetic values and environmental variances. [source] STRICTLY LIABLE: GOVERNMENTAL USE OF THE PARENT,CHILD RELATIONSHIP AS A BASIS FOR HOLDING VICTIMS LIABLE FOR THEIR CHILD'S WITNESS TO DOMESTIC VIOLENCEFAMILY COURT REVIEW, Issue 1 2006Sharon N. ClarkeArticle first published online: 10 FEB 200 Studies estimate that between three and ten million children in the United States witness domestic violence annually. Although studies have demonstrated a co-occurrence of domestic violence and child abuse, there is no concrete evidence to support the assumption that a child's exposure to domestic violence increases the risk to the child of abuse or neglect. Recently the New York State Court of Appeals determined that a child's witness to abuse does not suffice, in and of itself, to show that removal of the child is necessary or that removal is in the "best interests" of the child. Programs which have developed alternatives to presumptive removal understand the importance of viewing the interests of the battered parent and children as being in accord with each other rather than in opposition. Private and government sponsored programs have demonstrated some success in protecting the parent-child relationship, ensuring the safety of both parent and child, and increasing accountability of batterers while reducing the necessity for removals. Alternative programs are less costly to the state than foster care, and emotionally less costly to the families. [source] Escherichia coli mediated urinary tract infections: Are there distinct uropathogenic E. coli (UPEC) pathotypes?FEMS MICROBIOLOGY LETTERS, Issue 2 2005Carl F. Marrs Abstract A variety of virulence genes are associated with Escherichia coli mediated urinary tract infections. Particular sets of virulence factors shared by bacterial strains directing them through a particular pathogenesis process are called a "pathotype." Comparison of co-occurrence of potential urinary tract infection (UTI) virulence genes among different E. coli isolates from fecal and UTI collections provides evidence for multiple pathotypes of uropathogenic E. coli, but current understanding of critical genetic differences defining the pathotypes is limited. Discovery of additional E. coli genes involved in uropathogenesis and determination of their distribution and co-occurrences will further define UPEC pathotypes and allow for a more detailed analysis of how these pathotypes might differ in how they cause disease. [source] The influence of oxygen saturation on the distributional overlap of predator (cod, Gadus morhua) and prey (herring, Clupea harengus) in the Bornholm Basin of the Baltic SeaFISHERIES OCEANOGRAPHY, Issue 1 2002Stefan Neuenfeldt Environmental heterogeneity can create boundary conditions for the co-occurrence of marine predators and their prey. If one or both are spatially constrained by their tolerance to environmental variables, then spatial differences in the availability of possible habitats define the volume of distributional overlap. Cod (Gadus morhua L.) and its prey, herring (Clupea harengus L.), in the vertically stratified Bornholm Basin of the Baltic Sea are presented as an example. A non-linear model was used to estimate oxygen avoidance thresholds for both species. Herring avoided oxygen saturation levels below 50%, while cod tolerated oxygen saturation down to 16%. The threshold of 50% oxygen saturation, below which cod could not encounter its prey, herring, was applied to a time series of vertical oxygen profiles from the centre of the Bornholm Basin to estimate the size of the overlap volume during the winter period from 1958 to 1999. Dependent on the oxygenation of the deep-water, the overlap volume varied between 57 km3 and 250 km3. [source] Species co-occurrence, nestedness and guild,environment relationships in stream macroinvertebratesFRESHWATER BIOLOGY, Issue 9 20092Article first published online: 2 JUN 200, JANI HEINO Summary 1. Describing species distribution patterns and the underlying mechanisms is at the heart of ecological research. A number of recent studies have used null model approaches to explore mechanisms behind spatial variation in community structure. 2. However, unexplored questions are the degree to which single guilds of potentially competing stream macroinvertebrate species show: (i) interspecific segregation among-stream sites (i.e. occur together less often than expected by chance), suggesting competitive interactions; (ii) interspecific aggregation (i.e. occur together more often than expected by chance), suggesting similar responses to the environment; (iii) comply with nestedness, suggesting the existence of selective extinctions or colonisations and (iv) show similar environmental relationships. 3. The present analyses showed that guilds of stream macroinvertebrates exhibit non-random co-occurrence patterns that were generally contingent on the weighting of sites by stream size. Despite significant segregation of species, each guild also showed significantly nested patterns. Species richness was correlated with different environmental factors between the guilds, although these correlations were relatively low. By contrast, correlations between the major ordination axes and key environmental variables were slightly stronger in canonical correspondence analysis, and generally the same factors were most strongly correlated with variation in the species composition of each guild. 4. The present findings are the first to show that species within each stream macroinvertebrate guild show significant negative co-occurrence at the among-stream riffle scale. These findings present challenges for future studies that aim to disentangle whether these patterns comply with the habitat checkerboard or the competitive checkerboard explanations. [source] Taxon-specific reaction norms to predator cues in a hybrid Daphnia complexFRESHWATER BIOLOGY, Issue 7 2007JUSTYNA WOLINSKA Summary 1. Previous studies have shown that interspecific hybridisation is common among taxa from the Daphnia galeata/hyalina/cucullata species complex. We investigated the influence of predator kairomones on the morphology and life histories of nine clones belonging to three taxa (pure D. galeata, F1 hybrids between D. galeata and D. hyalina, and backcrossed D. hyalina) of this species complex. Predators exerting positive (fish) and negative (Chaoborus larvae) size-selective predation were tested. 2. The most responsive traits were size at maturity and size of neonates. Despite large between-clone variation, discriminant analysis revealed that the three taxa were distinct from each other in key life-history traits. F1 hybrids did not react in an intermediate way compared to the other taxa: the multivariate distances between F1 hybrids and either taxon were larger than between pure D. galeata and backcrossed D. hyalina. 3. The average plasticity (calculated across all traits) was similar for all three taxa. With regard to the size at maturity and neonate body size, the strength of the response was a function of the intrinsic values of these traits expressed in the control. For example, for size at maturity, smaller individuals showed a significantly stronger reaction to Chaoborus kairomones than larger ones. 4. Finally, we monitored seasonal changes in body size, egg number and population density of pure D. galeata and F1 hybrids in Greifensee (Switzerland). The two taxa experienced similar seasonal changes in body size but, on some sampling dates, they differed in mean egg number. The observed seasonal changes in Daphnia body size were consistent with what would be expected if the predator assemblage shifted from fish to Chaoborus over the course of the summer. The fluctuations in the frequencies of Daphnia taxa, however, were not related to seasonal variation in Daphnia body size. 5. Experimental data suggest that temporally heterogeneous predation regimes might be an important condition stabilising the co-occurrence of Daphnia hybrids with parental taxa. Predation regimes, however, cannot solely explain dynamic changes in taxon frequency in Greifensee. [source] Common genetic influences underlie comorbidity of migraine and endometriosisGENETIC EPIDEMIOLOGY, Issue 2 2009Dale R. Nyholt Abstract We examined the co-occurrence of migraine and endometriosis within the largest known collection of families containing multiple women with surgically confirmed endometriosis and in an independent sample of 815 monozygotic and 457 dizygotic female twin pairs. Within the endometriosis families, a significantly increased risk of migrainous headache was observed in women with endometriosis compared to women without endometriosis (odds ratio [OR] 1.57, 95% confidence interval [CI]: 1.12,2.21, P=0.009). Bivariate heritability analyses indicated no evidence for common environmental factors influencing either migraine or endometriosis but significant genetic components for both traits, with heritability estimates of 69 and 49%, respectively. Importantly, a significant additive genetic correlation (rG = 0.27, 95% CI: 0.06,0.47) and bivariate heritability (h2=0.17, 95% CI: 0.08,0.27) was observed between migraine and endometriosis. Controlling for the personality trait neuroticism made little impact on this association. These results confirm the previously reported comorbidity between migraine and endometriosis and indicate common genetic influences completely explain their co-occurrence within individuals. Given pharmacological treatments for endometriosis typically target hormonal pathways and a number of findings provide support for a relationship between hormonal variations and migraine, hormone-related genes and pathways are highly plausible candidates for both migraine and endometriosis. Therefore, taking into account the status of both migraine and endometriosis may provide a novel opportunity to identify the genes underlying them. Finally, we propose that the analysis of such genetically correlated comorbid traits can increase power to detect genetic risk loci through the use of more specific, homogenous and heritable phenotypes. Genet. Epidemiol. 2008. © 2008 Wiley-Liss, Inc. [source] Quantitative and qualitative evaluation of neuromotor behaviour in children with a specific speech and language disorderINFANT AND CHILD DEVELOPMENT, Issue 1 2002Michele Noterdaeme Abstract Several studies have described problems in a wide area of motor functions in language impaired children. The purpose of this study was to identify the nature of the motor deficits in two subgroups of language impaired children. A standard neurological examination was performed on 18 children with an expressive language disorder and 21 children with a receptive language disorder. The motor performance of the language disordered children was compared with the motor performance of 23 normal children. The standard neurological examination allowed for a qualitative and quantitative assessment of five specific neurological subsystems. Handedness was determined for all children. The language impaired children had more motor problems than the control children on most neurological subsystems. There were few statistically significant differences between the two groups of language impaired children. An excess in left-handedness was established in the group of children with a receptive language disorder. There was a co-occurrence of verbal and non-verbal deficits in language impaired children. As these motor problems put an additional burden on the development of language impaired children, they should be diagnosed as early as possible. Copyright © 2002 John Wiley & Sons, Ltd. [source] The impact of the positive Indian Ocean dipole on Zimbabwe droughtsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 15 2008D. Manatsa Abstract A comparative study of the impact of the anomalous positive Indian Ocean SST gradient, referred to as the Indian Ocean Dipole/Zonal Mode (IODZM), and El Niño-Southern Oscillation (ENSO) on Zimbabwe seasonal rainfall variability for the period 1940,1999, is documented. Composite techniques together with simple and partial correlation analyses are employed to segregate the unique association related to IODZM/ENSO with respect to the Zimbabwe seasonal rainfall. The analysis reveals that the IODZM impact on the country's summer rainfall is overwhelming as compared to that of ENSO when the two are in competition. The IODZM influence remains high (significant above 99% confidence level), even after the influence of ENSO has been removed, while that of ENSO collapses to insignificance (even at 90% confidence level) when the IODZM contribution is eliminated. The relationship between ENSO and Zimbabwe seasonal rainfall seems to be sustained through El Niño occurring in the presence of positive IODZM events. However, when the co-occurring positive IODZM and El Niño events are removed from the analysis, it is apparently clear that ENSO has little to do with the country's rainfall variability. On the other hand, positive IODZM is mostly associated with the rainfall deficits, whether or not it co-occurs with El Niño. However, the co-occurrence of the two events does not necessarily suggest that El Niño influences droughts through the positive IODZM events. The El Niño event components during co-occurrence seem to be unrelated (at least linearly) to the droughts, while the positive IODZM events display a relatively strong relationship that is significant above the 95% confidence level. It thus becomes important to extend the study of this nature to cover the whole of southern Africa, so that the extent of the impact of the phenomena can be realized over the whole region. Copyright © 2008 Royal Meteorological Society [source] Basin-wide warming of the Indian Ocean during El Niño and Indian Ocean dipole yearsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2007J. S. Chowdary Abstract Basin-wide wintertime surface warming is observed in the Indian Ocean during El Niño years. The basin-wide warming is found to be stronger when El Niño and Indian Ocean Dipole (IOD) co-occur. The mechanisms responsible for the basin-wide warming are different for the years with El Niño only (El Niño without IOD) and for the co-occurrence (both El Niño and IOD) years. Strong westward propagation of downwelling Rossby waves is observed in the southern Indian Ocean during the IOD years. Such strong propagation is not seen in the case of the El Niño-only years. This indicates that the ocean dynamics play an important role in winter warming of the western Indian Ocean during the IOD years. The weak easterly wind anomalies in the El Niño-only years show no measurable impact on the Wyrtki Jets, but weakening or reversal of these jets is seen in the IOD years. This strongly suggests that the variability related to surface circulation is due to the local IOD forcing rather than El Niño induced wind anomaly. For the El Niño-only composites, surface heat fluxes (mainly latent heat flux and short wave radiation) play an important role in maintaining the basin-wide surface warming in the Indian Ocean. In the IOD-only composites (when there is no El Niño in the Pacific), such basin-wide warming is not seen because of the absence of ENSO (El Niño and Southern Oscillation) induced subsidence over the eastern Indian Ocean. For the years in which both El Niño in the Pacific and dipole in the Indian Ocean co-occur, warming in the western Indian Ocean is due to the ocean dynamics and that in the eastern Indian Ocean is due to the anomalous latent heat flux and solar radiation. Copyright © 2007 Royal Meteorological Society [source] Relationship between cribra orbitalia and enamel hypoplasia in the early medieval Slavic population at Borovce, SlovakiaINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 3 2008Z. Obertová Abstract Cribra orbitalia and enamel hypoplasia were examined in an early medieval (8th to beginning of 12th century AD) skeletal sample of 451 individuals from Borovce, Slovakia. More than 40% of these individuals died before reaching 20 years of age. The relationship between the occurrence of orbital and enamel lesions was analysed by focusing on the age-specific distribution, and on its influence on demographic parameters. Both features were found in 11.2% of the observed skulls. The presence of orbital and dental lesions showed a considerable impact on mortality as well as the life expectancy. Generally, the highest mortality was observed among 0,4 year old individuals. The greatest discrepancy in the demographic parameters, however, appeared between the affected and unaffected individuals aged 10,14 and 15,19 years. In these two age groups the co-occurrence of both lesions was most frequently recorded. These individuals obviously had a history of sickness, and thus could not cope with further bouts of disease and with the increased physiological demands of pubertal growth. The missing correlation in younger age categories can be largely explained by the difficulty of macroscopically examining the permanent dentition, since an interrelationship between the age at hypoplasia development and the occurrence of cribra orbitalia was detected. Several differences between the individuals with enamel defects and both conditions were observed in the distribution of age at hypoplasia formation. According to these results, several factors, such as impaired health status, growth demands and diet, influence the development of enamel hypoplasia and cribra orbitalia in a particular population. It is possible that after reaching a certain threshold, the underlying factors act synergistically in a kind of vicious cycle as the balance between the immune system, metabolism, and exogenous factors such as pathogens and nutrition, is disturbed. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Co-Occurrence of Chronic Diseases and Geriatric Syndromes: The Health and Retirement StudyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2009Pearl G. Lee MD OBJECTIVES: To analyze the co-occurrence, in adults aged 65 and older, of five conditions that are highly prevalent, lead to substantial morbidity, and have evidence-based guidelines for management and well-developed measures of medical care quality. DESIGN: Secondary data analysis of the 2004 wave of the Health and Retirement Study (HRS). SETTING: Nationally representative health interview survey. PARTICIPANTS: Respondents in the 2004 wave of the HRS aged 65 and older. MEASUREMENTS: Self-reported presence of five index conditions (three chronic diseases (coronary artery disease, congestive heart failure, and diabetes mellitus) and two geriatric syndromes (urinary incontinence and injurious falls)) and demographic information (age, sex, race, living situation, net worth, and education). RESULTS: Eleven thousand one hundred thirteen adults, representing 37.1 million Americans aged 65 and older, were interviewed. Forty-five percent were aged 76 and older, 58% were female, 8% were African American, and 4% resided in a nursing home. Respondents with more conditions were older and more likely to be female, single, and residing in a nursing home (all P<.001). Fifty-six percent had at least one of the five index conditions, and 23% had two or more. Of respondents with one condition, 20% to 55% (depending on the index condition) had two or more additional conditions. CONCLUSION: Five common conditions (3 chronic diseases, 2 geriatric syndromes) often co-occur in older adults, suggesting that coordinated management of comorbid conditions, both diseases and geriatric syndromes, is important. Care guidelines and quality indicators, rather than considering one condition at a time, should be developed to address comprehensive and coordinated management of co-occurring diseases and geriatric syndromes. [source] Are ectoparasite communities structured?JOURNAL OF ANIMAL ECOLOGY, Issue 6 2006Species co-occurrence, null models, temporal variation Summary 1We studied temporal variation in the structure of flea communities on small mammalian hosts from eastern Slovakia using null models. We asked (a) whether flea co-occurrences in infracommunities (in the individual hosts) in different hosts as well as in the component communities (in the host species) demonstrate a non-random pattern; (b) whether this pattern is indicative of either positive or negative flea species interactions; (c) whether this pattern varies temporally; and (d) whether the expression of this pattern is related to population size of either fleas or hosts or both. 2We constructed a presence/absence matrix of flea species for each temporal sample of a host species and calculated four metrics of co-occurrence, namely the C -score, the number of checkerboard species pairs, the number of species combinations and the variance ratio (V -ratio). Then we compared these metrics with the respective indices calculated for 5000 null matrices that were assembled randomly using two algorithms, namely fixed-fixed (FF) and fixed-equiprobable (FE). 3Most co-occurrence metrics calculated for real data did not differ significantly from the metrics calculated for simulated matrices using the FF algorithm. However, the indices observed for 42 of 75 presence/absence matrices differed significantly from the null expectations for the FE models. Non-randomness was detected mainly by the C -score and V -ratio metrics. In all cases, the direction of non-randomness was the same, namely the aggregation, not competition, of flea species in host individuals and host species. 4The inclusion or exclusion of the uninfested hosts in the FE models did not affect the results for individual host species. However, exclusion of the uninfested host species led to the acceptance of the null hypothesis for only six of 13 temporal samples of the component flea communities for which non-randomness was detected when the uninfested hosts were included in the analysis. 5In most host species, the absolute values of the standardized size effect of both the C -score and V -ratio increased with an increase in host density and a concomitant decrease in flea abundance and prevalence. 6Results of this study demonstrated that (a) flea assemblages on small mammalian hosts were structured at some times, whereas they appeared to be randomly assembled at other times; (b) whenever non-randomness of flea co-occurrences was detected, it suggested aggregation but never segregation of flea species in host individuals or populations; and (c) the expression of structure in flea assemblages depended on the level of density of both fleas and hosts. [source] | ||||||||||||||||||||||||||||||||||||||||||||||