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Substantial Variation (substantial + variation)
Selected AbstractsEvaluation of Three Algorithms to Identify Incident Breast Cancer in Medicare Claims DataHEALTH SERVICES RESEARCH, Issue 5 2007Heather T. Gold Objective. To test the validity of three published algorithms designed to identify incident breast cancer cases using recent inpatient, outpatient, and physician insurance claims data. Data. The Surveillance, Epidemiology, and End Results (SEER) registry data linked with Medicare physician, hospital, and outpatient claims data for breast cancer cases diagnosed from 1995 to 1998 and a 5 percent control sample of Medicare beneficiaries in SEER areas. Study Design. We evaluate the sensitivity and specificity of three algorithms applied to new data compared with original reported results. Algorithms use health insurance diagnosis and procedure claims codes to classify breast cancer cases, with SEER as the reference standard. We compare algorithms by age, stage, race, and SEER region, and explore via logistic regression whether adding demographic variables improves algorithm performance. Principal Findings. The sensitivity of two of three algorithms is significantly lower when applied to newer data, compared with sensitivity calculated during algorithm development (59 and 77.4 percent versus 90 and 80.2 percent, p<.00001). Sensitivity decreases as age increases, and false negative rates are higher for cases with in situ, metastatic, and unknown stage disease compared with localized or regional breast cancer. Substantial variation also exists by SEER registry. There was potential for improvement in algorithm performance when adding age, region, and race to an indicator variable for whether the algorithm determined a subject to be a breast cancer case (p<.00001). Conclusions. Differential sensitivity of the algorithms by SEER region and age likely reflects variation in practice patterns, because the algorithms rely on administrative procedure codes. Depending on the algorithm, 3,5 percent of subjects overall are misclassified in 1998. Misclassification disproportionately affects older women and those diagnosed with in situ, metastatic, or unknown-stage disease. Algorithms should be applied cautiously to insurance claims databases to assess health care utilization outside SEER-Medicare populations because of uneven misclassification of subgroups that may be understudied already. [source] Effect of molecular architecture and size of mesogen on phase behavior and photoactive properties of photoactive liquid crystalline hyperbranched polyester epoxies containing benzylidene moietyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2008V. Srinivasa Rao Abstract A series of photoactive liquid crystalline linear and hyperbranched polyester epoxies were synthesized by polyaddition of photoactive bis benzylidene alkanone diol monomers and terephthalic acid and trimesic acid respectively with good yield. The effect of molecular architecture (linear and hyperbranched), size of mesogenic unit (cyclic and acyclic units) on the physicochemical, thermal, mesogenic, and photoactive properties of hyperbranched polymers were studied and compared. Degree of branching of hyperbranched polymers was found to be in the range of 0.46,0.49. Monomers containing cyclic moieties only exhibited nematic mesophase, while all polymers exhibited typical nematic mesophase. Intermolecular photo cycloaddition reaction was studied by ultraviolet,visible spectra (UV,vis) and NMR spectroscopy and photo viscosity measurement of UV irradiated polymer solutions. Faster photo induced behavior of hyperbranched polymers containing acyclic alkanone moiety, as compared to polymers containing cycloalkanone moieties, was observed. The change in the refractive index was found to be in the range of 0.02,0.024. Substantial variation of refractive index indicates that this polymer could be used for optical recording. All the polymers were also found to be fluorescent in nature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 552,563, 2008 [source] A systematic review of prevalence studies of dementia in Parkinson's diseaseMOVEMENT DISORDERS, Issue 10 2005Dag Aarsland MD Abstract Substantial variation in the prevalence of dementia in Parkinson's disease (PDD) has been reported. The aim of this study was to review systematically and critically previous studies of the prevalence of PDD using PubMed to search the literature. Studies focusing on PD and PDD, as well as those examining on the epidemiology of dementia subtypes, were included. Predefined inclusion and exclusion criteria were used and the quality of the studies included was rated. Articles were included if: (1) the proportion of PDD among patients with either PD or dementia was reported in an original study; (2) patients had been subjected to prospective clinical examination; and (3) strategies to include all subjects with either PD or dementia within the community or hospital clinics within a geographical area were employed. Twelve studies of the prevalence of PD or PDD (1,767 patients included) and 24 prevalence studies of dementia subtypes (4,711 patients included) met the inclusion criteria. In the PD/PDD studies, the proportion (mean and 95% confidence interval) with PDD in PD was 24.5% (17.4,31.5). There were significant methodological variations between studies and in the four studies that matched the quality criteria most closely, the rate of PDD was 31.1% (20.1,42.1). The prevalence of PDD was estimated as 0.5% in subjects 65 years or older. The percentage of PDD among those with dementia was 3.6% (3.1,4.1), with an estimated prevalence of PDD of 0.2% in subjects aged 65 years or older. Despite methodological variation, this systematic review suggests that 24 to 31% of PD patients have dementia, and that 3 to 4% of the dementia in the population would be due to PDD. The estimated prevalence of PDD in the general population aged 65 years and over is 0.2 to 0.5%. © 2005 Movement Disorder Society [source] Variation in pathogen aggressiveness within a metapopulation of the Cakile maritima,Alternaria brassicicola host,pathogen associationPLANT PATHOLOGY, Issue 3 2005P. H. Thrall Variation in aggressiveness and its consequences for disease epidemiology were studied in the Cakile maritima,Alternaria brassicicola host,pathogen association. Variability in pathogen growth rates and spore production in vitro, as well as disease severity and lesion growth rate on C. maritima in glasshouse inoculation trials, were investigated. Substantial variation was found in growth rates among individual A. brassicicola isolates, as well as among pathogen populations. A significant trade-off also existed between growth and spore production, such that faster-growing isolates produced fewer spores per unit area. While there was little evidence for a link between growth in vitro and either disease severity or lesion development among fast- vs slow-growth isolate classes at the individual isolate level, the results suggest that variation in pathogen fitness components associated with aggressiveness may influence disease dynamics in nature. An analysis using an independent data set of disease prevalence in the associated host populations found a significant positive relationship between the average growth rate of pathogen populations in vitro and disease progress over the growing season in wild host populations. Trade-offs such as those demonstrated between growth rate and spore production may contribute to the maintenance of variation in quantitatively based host,pathogen interactions. [source] Refining exposure definitions for studies of periodontal disease and systemic disease associationsCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 6 2008Ryan T. Demmer Abstract,,, Background:, Substantial variation exists in reported associations between periodontal infections and cardiovascular disease. Imprecise periodontal exposure definitions are possible contributors to this variability. We studied appropriate exposure definitions for studying associations between clinical periodontal disease (PD) and systemic disease. Methods:, Data originate from men and women aged 20,79 enrolled in the Study of Health in Pomerania (SHIP) from 1997,2001. Age and sex-adjusted correlation analysis identified PD definitions with the highest cross-sectional associations with three subclinical markers of systemic disease: plasma fibrinogen (n = 3481), serum hemoglobin A1c (HbA1c) (n = 3480), and common carotid artery intima-media thickness (c-IMT) (n = 1745, age , 45). Results:, In men and women, percent of sites with attachment loss (AL) ,6 mm and tooth loss both revealed the highest correlation with HbA1c (, = 0.11; several other definitions related similarly), while the strongest fibrinogen correlation was observed with percent of sites with pocket depth ,3 mm (, = 0.19). Findings for c-IMT among men were strongest for percent of sites with AL ,6 mm (, = 0.14; several other definitions related similarly) while among women, percent of sites with pocket depth ,5 or 6 mm had the highest observed correlation (, = 0.13). Conclusions:, A range of near optimal definitions varied according to gender and whether the systemic disease marker reflected an acute or chronic situation. Pocket depth was more strongly correlated with the acute marker fibrinogen while attachment and tooth loss tended to be more strongly correlated with the chronic markers, HbA1c, and c-IMT. These findings can be useful in designing future studies investigating the association between PD and systemic disease. [source] The molecular composition of soil organic matter as determined by 13C NMR and elemental analyses and correlation with pesticide sorptionEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2006R. Ahmad Summary Although the chemical composition of soil organic matter (SOM) is known to significantly influence sorption of pesticides and other pollutants, it has been difficult to determine the molecular nature of SOM in situ. Here, using 13C nuclear magnetic resonance (NMR) data and elemental composition in a molecular mixing model, we estimated the molecular components of SOM in 24 soils from various agro-ecological regions. Substantial variations were revealed in the molecular nature of SOM. As a proportion of soil carbon the proportion of the carbonyl component ranged from 0.006 to 0.05, charcoal from 0 to 0.15, protein from 0.09 to 0.29, aliphatic from 0.14 to 0.30, carbohydrate from 0.21 to 0.31, and lignin from 0.05 to 0.42. The relationships between Koc (sorption per unit mass of organic carbon) of carbaryl (1-naphthyl methylcarbamate) and phosalone (S- 6-chloro-2,3-dihydro-2-oxobenzoxazol-3-ylmethyl O,O -diethyl phosphorodithioate) and the molecular nature of organic matter in the soils were significant. Of the molecular components estimated, lignin and charcoal contents correlated best with sorption of carbaryl and phosalone. Aliphatic, carbohydrate and protein contents were found to be negatively correlated with the Koc of both pesticides. The study highlights the importance of the molecular nature of SOM in determining sorption affinities of non-ionic pesticides and presents an indirect method for sorption estimation of pesticides. [source] The impact of sleep interruptions on vital measurements and chronic fatigue of female caregivers providing home care in JapanNURSING & HEALTH SCIENCES, Issue 1 2006Keiko Tsukasaki rn, msn Abstract, The purposes of this study were to examine the impact of sleep interruptions on diurnal changes in blood pressure and chronic fatigue in middle-aged and elderly caregivers by using a cross-sectional quantitative method. Thirty-five female caregivers who were not taking antihypertensive and/or sleeping drugs were recruited for this study. Blood pressure was monitored over a 24 h period. Sleeping or waking periods were monitored with an actigraph. Fatigue was determined from a self-administered questionnaire. Participants were classified into four groups by cause of sleep interruption. One-way analysis of variance showed no differences in blood pressure, but hypertension was prevalent (40%). Sleep duration differed significantly, with the longest duration for those scheduled to wake up for care. Substantial variations were identified in the eight subcategories of chronic fatigue, with those without sleep interruption having the worst profile. This suggests that multiple factors in addition to sleep interruption affect the care burden. [source] Biogeographic variation in nest placement: a case study with conservation implicationsDIVERSITY AND DISTRIBUTIONS, Issue 1 2002Jennifer M. Parody Abstract. Local habitat characteristics are often used to describe a species' niche despite the fact that habitat use can vary across the geographical range. We sought to quantify variation in habitat preferences by asking how nesting habit varies within and between populations of Bell's vireo (Vireo bellii) across its geographical range. Analyses of detailed nest placement data from three localities (Kansas, eastern New Mexico and western New Mexico) showed a general trend towards use of dense vegetation. However, there was substantial variation in nest placement and vegetation at nest sites between localities. Furthermore, a review of nest placement data from the literature shows strong differences in nest heights and species of trees even between populations less than 100 km apart. We evaluate these results in light of conservation and suggest that to be most effective, habitat conservation plans should be based on data collected at the locality where the population of interest occurs. [source] Estimation of regional material yield from coastal landslides based on historical digital terrain modelling,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2005C. J. Hapke Abstract High-resolution historical (1942) and recent (1994) digital terrain models were derived from aerial photographs along the Big Sur coastline in central California to measure the long-term volume of material that enters the nearshore environment. During the 52-year measurement time period, an average of 21 000 ± 3100 m3 km,1 a,1 of material was eroded from nine study sections distributed along the coast, with a low yield of 1000 ± 240 m3 km,1 a,1 and a high of 46 700 ± 7300 m3 km,1 a,1. The results compare well with known volumes from several deep-seated landslides in the area and suggest that the processes by which material is delivered to the coast are episodic in nature. In addition, a number of parameters are investigated to determine what influences the substantial variation in yield along the coast. It is found that the magnitude of regional coastal landslide sediment yield is primarily related to the physical strength of the slope-forming material. Coastal Highway 1 runs along the lower portion of the slope along this stretch of coastline, and winter storms frequently damage the highway. The California Department of Transportation is responsible for maintaining this scenic highway while minimizing the impacts to the coastal ecosystems that are part of the Monterey Bay National Marine Sanctuary. This study provides environmental managers with critical background data on the volumes of material that historically enter the nearshore from landslides, as well as demonstrating the application of deriving historical digital terrain data to model landscape evolution. Published in 2005 by John Wiley & Sons, Ltd. [source] Intraspecific variation in the strength of density dependence in aphid populationsECOLOGICAL ENTOMOLOGY, Issue 5 2004Anurag A. Agrawal Abstract., 1. Experimental evidence is presented for positive, negative, and no density dependence from 32 independent density manipulations of milkweed aphids (Aphis nerii) in laboratory and field experiments. This substantial variation in intraspecific density dependence is associated with temperature and host-plant species. 2. It is reported that as population growth rate increases, density dependence becomes more strongly negative, suggesting that the monotonic definition of density dependence used in many common population models is appropriate for these aphids, and that population growth rate and carrying capacity are not directly proportional. 3. For populations that conform to these assumptions, population growth rate may be widely applicable as a predictor of the strength of density dependence. [source] Unplanned attempts to quit smoking: a qualitative explorationADDICTION, Issue 7 2010Rachael L. Murray ABSTRACT Aims To gain a greater understanding of the process of unplanned attempts to quit smoking and the use of support in such attempts. Design Qualitative study using semi-structured interviews with 20 smokers and ex-smokers. Setting Twenty-four general practices in Nottinghamshire, UK. Participants Smokers and ex-smokers who reported that their most recent attempt to quit smoking was unplanned. Measurements Descriptions of the unplanned quit attempts and reported use of support within these. Findings Smokers who report making ,unplanned' quit attempts exhibit substantial variation in what they mean by this; many quit attempts reported as ,unplanned' were actually delayed and involved some planning and use of cessation support. Conclusions Reported ,unplanned' quit attempts often involve elements of planning and delay for quitters to access to cessation support. It is important, therefore, that smoking cessation services offer flexible and adaptable support which can be used readily by potential quitters. [source] Geographical and individual variation in echolocation calls of the intermediate leaf-nosed bat, Hipposideros larvatusETHOLOGY, Issue 8 2010Tinglei Jiang The cause and significance of variation in echolocation call frequency within hipposiderid bats is not well understood despite an increasing number of allopatric and sympatric examples being documented. We examined variation patterns in the resting frequency (RF) of echolocation calls emitted by the intermediate leaf-nosed bat, Hipposideros larvatus, on a broad geographical scale. Data mining technology and Kruskal,Wallis test both showed substantial variation with a longitudinal pattern in RF in H. larvatus among colonies, and this variation was associated with geographical distance and not body size. In addition, we found that a high degree of variability between individuals was hidden under the geographical variation. The results support an effect of random cultural drift, and challenge the prey detection hypothesis. Moreover, an acoustic difference among local island colonies may be indicative of a vocal dialect. We found that each colony of H. larvatus seems to maintain a ,private bandwidth', which could be used for colony identity and individual communication thus helping individuals and colonies to get a number of fitness benefits. [source] Reactivity Pattern in the Room-Temperature Activation of NH3 by the Main-Group Atomic Ions Ga+, Ge+, As+ and Se+EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2010Gregory K. Koyanagi Abstract The activation of ammonia by the main-group cations Ga+, Ge+, As+ and Se+ has been explored both experimentally and theoretically. ICP/SIFT tandem mass spectrometer measurements of room-temperature kinetics have revealed a substantial variation in rates and product distributions across the Periodic Table of Elements. The main features of the observed primary chemistry include H-atom elimination, ammonia addition and a cation-assisted proton transfer to yield NH4+ that is second order in ammonia. These observations are shown to be completely consistent with computed potential energy surfaces for the reactions of each of the four atomic cations. Dehydrogenation by the elimination of molecular hydrogen, not observed experimentally, is shown by the calculations to be inhibited by the presence of a kinetic barrier. [source] The Original Maturity of Corporate Bonds: The Influence of Credit Rating, Asset Maturity, Security, and Macroeconomic ConditionsFINANCIAL REVIEW, Issue 2 2006Geetanjali Bali G24 Abstract We examine the determinants of the new issue maturity of corporate bonds. As credit rating decreases, new bond issues have longer maturities, but substantial variation in maturity within each rating class remains. We seek to explain the variation of new issue maturity within credit classes. We find that asset maturity, security covenants, and macroeconomic conditions influence the new issue maturity of bonds within rating categories. [source] Growth and population size of crayfish in headwater streams: individual- and higher-level consequences of acidificationFRESHWATER BIOLOGY, Issue 7 2004Steven M. Seiler Summary 1. Environmental stress may have indirect positive effects on population size through modification of food-web interactions, despite having negative effects on individuals. Here we evaluate the individual- and population-level effects of acidification on crayfish (Cambarus bartonii) in headwater streams of the Allegheny Plateau (PA, U.S.A.) with field experiments and survey data. Median baseflow pH of 24 study reaches in nine streams varied from 4.4 to 7.4, with substantial variation found both among and within streams. 2. Two bioassays were conducted to evaluate the relationship between stream pH and crayfish growth rates. Growth rates were always higher in circumneutral reaches than in acidic reaches. Crayfish originating in acidic water grew less when transplanted into neutral water than did crayfish originating in neutral water, providing some evidence for a cost of acclimation to acidity. 3. Stream surveys showed that fish were less abundant and crayfish more abundant in acidified streams than in circumneutral streams. Crayfish density was sixfold higher in reaches with the lowest pH relative to circumneutral reaches. Large crayfish made up a higher proportion of crayfish populations at sites with high fish biomass, consistent with the hypothesis that fish predation on small individuals may be limiting crayfish population size at these sites. 4. Although individual crayfish suffered lower growth in acidified streams, increased acidity appeared to cause an increase in crayfish population size and shifts in size structure, possibly by relieving predation pressure by fish. [source] ,15N of zooplankton species in subarctic lakes in northern Sweden: effects of diet and trophic fractionationFRESHWATER BIOLOGY, Issue 5 2004J. Karlsson Summary 1. To assess the use of stable nitrogen isotopes (,15N) for reconstructing trophic relationships in planktonic food webs, crustacean zooplankton species and pelagic dissolved and particulate matter were analysed in 14 subarctic lakes in northern Sweden. The lakes are situated along an altitudinal gradient and show a substantial variation in nutrient content and energy mobilization by bacterioplankton and phytoplankton. 2. The ,15N of dissolved and particulate matter was comparatively low, suggesting efficient N recycling and low losses of depleted N from the pelagic zone of these unproductive lakes. 3. Copepods had a systematically higher ,15N than cladocerans, with an average difference of 3.1,4.9, within lakes, implying different trophic positions of the two groups. Comparisons of nitrogen pools and energy fluxes suggest that the low cladoceran ,15N was a result of feeding on bacteria. 4. The difference in ,15N between copepods and cladocerans declined with decreasing bacterioplankton production among lakes, due either to increasing trophic isotope fractionation or decreasing relative importance of bacteria in the diet of cladocerans. [source] Canopy structure in savannas along a moisture gradient on Kalahari sandsGLOBAL CHANGE BIOLOGY, Issue 3 2004Robert J. Scholes Abstract Measurements of tree canopy architecture were made at six savanna sites on deep, sandy soils, along a gradient of increasing aridity. There was substantial variation in the leaf area estimated within each site, using the same sample frame, but different measurement techniques. The trends in canopy properties in relation to the aridity gradient were consistent, regardless of the technique used for estimating the properties. The effective plant area index for the tree canopy (the sum of the stem area index and the leaf area index (LAI)) declined from around 2 to around 0.8 m2 m,2 over a gradient of mean annual rainfall from 1000 to 350 mm. Stems contributed 2,5% of the tree canopy plant area index. Since the tree canopy cover decreased from 50% to 20% over this aridity range, the leaf area index within the area covered by tree canopies remained fairly constant at 3,4 m2 m,2. Tree leaves tended from a horizontal orientation to a more random orientation as the aridity increased. On the same gradient, the leaf minor axis dimension decreased from around 30 mm to around 3 mm, and the mean specific leaf area decreased from 14 to 5 m2 kgha,1. There was good agreement between LAI observed in the field using a line ceptometer and the LAI inferred by the MODIS sensor on the Terra satellite platform, 2 months later in the same season. [source] Quality of life in partners of people with congestive heart failure: gender and involvement in careJOURNAL OF ADVANCED NURSING, Issue 7 2009Marie Louise Luttik Abstract Title.,Quality of life in partners of people with congestive heart failure: gender and involvement in care. Aim., This paper is a report of a study conducted to investigate quality of life in partners of people with congestive heart failure in comparison to individuals living with a healthy partner. Background., Congestive heart failure is a chronic debilitating disease with severe symptoms and complex treatment. The support of partners is essential in the management of congestive heart failure. Living with a chronic illness generally affects the quality of life of patients and their partners. Method., Data were collected using a cross-sectional, comparative design between October 2002 and February 2005 with 303 partners of people with congestive heart failure. Reference data were collected in 304 age- and gender-matched individuals living with a healthy partner, drawn from the general population. All respondents completed questionnaires at home on quality of life and general well-being. Analysis of variance was used to analyse the data. Findings., Overall, differences in quality of life between partners of people with heart failure and matched controls were small. However, substantial variation in the quality of life of partners was found by exploring the role of gender and involvement in care. Quality of life scores varied strongly for male and female partners who had to perform caregiving tasks. The performance of these caregiving tasks was negatively associated with the quality of life of female partners but not with that of male partners. Conclusion., Female partners especially should not be overlooked when they become involved in personal care tasks. Nurses should not be reluctant to involve male partners in caring for women with heart failure. [source] Testing biotic indicator taxa: the sensitivity of insectivorous mammals and their prey to the intensification of lowland agricultureJOURNAL OF APPLIED ECOLOGY, Issue 1 2008Michael J. O. Pocock Summary 1Changes to agricultural policy aim to extensify agriculture and increase biodiversity. However, it is not known how sensitive many taxa are to intensification. Sensitive taxa could be used as biotic indicators, to assess changes over time and the effectiveness of policy changes. 2We sampled shrews, bats and their prey (beetles, flies and moths) on matched pairs of sites and assessed the response in their abundance to aspects of intensification: increased agrochemical inputs (using abundance on matched organic and conventional cereal fields as a proxy), the switch from hay to silage (using abundance on matched hay and silage fields) and boundary loss (using abundance in the field and near the boundary as a proxy, in cereal and grass separately). We quantified the abundance-derived sensitivity of the taxa in order to assess their use as biotic indicators. 3There was substantial variation in the sensitivity of taxa to the three aspects of intensification. Most estimates (51%) of sensitivity to boundary loss were significant, but only 8% for increased agrochemical inputs and 16% for the switch from hay to silage. Sensitivity to one aspect of intensification was not significantly related to sensitivity to another. 4Insectivorous mammals were relatively insensitive to increased agrochemical inputs and the switch from hay to silage, but strongly sensitive to boundary loss. 5Taxa with significant sensitivity to increased agrochemical inputs included some Carabidae and Diptera. We found fewer significant differences in abundance between organic and conventional farms than previous workers, probably because we controlled for boundary characteristics, suggesting that the quality of field boundaries is important in influencing biodiversity differences between organic and conventional farms. 6The switch from hay to silage had a positive effect on some Coleoptera and Diptera but a substantial negative effect on Hepialidae (Lepidoptera). 7Synthesis and applications. The recorded sensitivity of taxa to changes in agricultural practices is highly variable. Therefore, the selection of biotic indicator taxa of agricultural intensification is not straightforward. If surveys of biotic indicator taxa are used to assess the effectiveness of changes in agricultural practice, empirical evidence should be used to select suitable taxa. [source] Snake activity affects seasonal variation in nest predation risk for birdsJOURNAL OF AVIAN BIOLOGY, Issue 4 2008Jinelle H. Sperry Variation in predator behavior has been proposed, but not tested, as a mechanism producing seasonal declines in avian nest success. We test this hypothesis by documenting seasonal activity of Texas ratsnakes Elaphe obsoleta and nest failure of endangered black-capped vireos Vireo atricapilla and golden-cheeked warblers Dendroica chrysoparia on which the snakes prey. Nest survival analysis was based on 880 vireo and 228 warbler nests and 3,060 snake locations from 62 radio-tracked snakes. Although nest success varied with snake activity for both birds, specific patterns differed substantially. Vireo daily nest survival was negatively correlated with snake activity over the three-year study, despite substantial variation among years in weather, and the fact that these birds are almost certainly a minor prey species of the ratsnakes. Warblers exhibited less clear-cut seasonal variation in nest success, and the association between nest success and snake activity was less pronounced than for vireos. Increased activity at warmer temperatures explained some of the seasonal change in snake movements, although mating may have accounted for a mid-season peak in activity. These results indicate that variation in predator behavior can be associated with and potentially cause seasonal changes in nest success, but also that these relationships are species specific even within the same community and may depend on aspects of the nesting ecology of the prey such as nest site selection. [source] The distribution and diversity of amphibian fauna of Lake Nabugabo and surrounding areasAFRICAN JOURNAL OF ECOLOGY, Issue 2004M. Behangana Abstract Six major vegetation types surrounding Lake Nabugabo were sampled for amphibians. These types were: shoreline zone (habitat type code A) representing vegetation on the shoreline about 2 m from the shoreline; Miscanthidium violaceum (B); Eragrostis-Loudetia (C); swamp forest (D); Cyperus papyrus (E); and medium altitude evergreen forest (F). A total of 168 days were spent in the field with a total of 288 1 h counts. Forty-eight counts were carried out in each vegetation type. Sampling was carried out between 17.00 and 24.00 h to coincide with the time amphibians are very active. Twenty-four species were recorded during the study period. These account for about 27.9% of total number of amphibian species recorded in Uganda. Four families were identified, which included: Ranidae (12 spp.), Hyperolidae (8 spp.), Bufonidae (3 spp.) and Pipidae (1 sp.). There was substantial variation in observed species composition among vegetation types. The most species rich habitat was the Eragrostis-Loudetia vegetation zone (17 spp.), followed by the swamp forest zone (14 spp.), then the M. violeceum swamp (11 spp.) and the shoreline (10 spp.). The most species poor sites were C. papyrus swamp (6 spp.) followed by the medium altitude forest (7 spp.). In terms of species abundance, the swamp forest and the M. violecium zones were the most important amphibian habitats for the common species while the Eragrostis-Laudetia zone stood out as the most important for the rare species. From the data collected, it can be deduced that the three most important habitats for the conservation of amphibian fauna in the study area are the Eragrostis-Laudetia, M. violeceum and the swamp forest zones. [source] Micro- and macroscopic characteristics to stage gonadal maturation of female Baltic codJOURNAL OF FISH BIOLOGY, Issue 2 2003J. Tomkiewicz A set of histological characteristics to judge ovarian development was established and used to elaborate morphological criteria of 10 maturity stages of Baltic cod Gadus morhua sampled throughout the annual cycle to represent different macroscopic maturity stages. The applied characteristics confirmed most stages of the macroscopic scale, but the separation of late immature and resting mature females remained imprecise. Atretic vitellogenic oocytes or encapsulated residual eggs identified the resting condition morphologically, but not all ovaries with visible signs of previous spawning showed such features. One ovarian stage that was previously classified as ,ripening' was changed to ,spawning', owing to the prevalence of hydrated eggs and empty follicles. Ovaries with malfunctions were defined by a separate stage. Macroscopic criteria were revised by comparing the gross anatomy of ovaries with their histology. Female length and gonado-somatic index supported stage definitions, but substantial variation in Fulton's condition factor and the hepato-somatic index rendered these of little use for this purpose. The time of sampling influenced staging accuracy. A female spawner probability function based on the proportion of ripening and ripe specimens in early spring seems to be the most appropriate method to estimate spawner biomass and reproductive potential. [source] Can a subjective poverty line be applied to China?JOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 8 2004Assessing poverty among urban residents in 199 For the first time, subjective poverty line methodology is applied to China. The data refer to 12 cities for the year 1999. A major conclusion is that poverty counts, based on the subjective poverty line, is surprisingly close to those obtained when applying the methodology used when providing official estimates on poverty in urban China. However, the opinions of the general public can differ considerably across cities. Applying the poverty line we find substantial variation across cities in the extent of poverty. Poverty status in urban China is very much related to education level of the household, to life cycle, as well as to labour market status. Copyright © 2004 John Wiley & Sons, Ltd. [source] CURRENT VARIABILITY SHAPES MORPHOLOGICAL COMPLEXITY IN COLONIAL STREAM DIATOMSJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Passy, S. I.1,2 & Freehafer, D.2 1Department of Biology, Rensselaer Polytechnic Institute, Troy, NY 12180; 2US Geological Survey, 425 Jordan Rd., Troy, NY 12180-8349 USA On August 27, 1999 diatoms were sampled, and current velocity was measured at 81 locations on a regular square sampling grid in an unshaded, cobble-bottom reach of White Creek, NY. The grid had an extent of 16 m2, interval, the distance between neighboring sampling points, of 0.5 m, and grain size, the size of the elementary sampling unit, of 0.01 m2. Six of the seven dominant benthic diatoms were colonial forms, including Diatoma vulgaris, Fragilaria capucina, F. crotonensis, Gomphoneis minuta, Melosira varians, and Synedra ulna. Their morphology and distribution were investigated from the perspective of fractal geometry and stream ecology, respectively. Fractal dimension of diatom colonies, indicative of their shape complexity, ranged from 1.06 to 1.54, demonstrating vast morphological variation from simple geometric shapes to complex outlines. The relative abundance of the six diatoms was regressed against current regime, which ranged from 0.03 to 0.66 m, s -1. All regression models were significant at P < 0.05 and explained between 55% and 94% of the variation in diatom distribution. The diatom niche breadth, i.e. the amount of environmental variability a species can tolerate, was defined from these models and showed substantial variation, from 5 to 14. The regression model of fractal dimension against niche breadth was significant and explained 76% of colonial shape variation, revealing a strong relationship between diatom colonial complexity and habitat variability. This finding suggests that environmental variability could create highly complex colonial morphologies in benthic diatoms as an evo-lutionary strategy for survival in unpredictable environments. [source] LANDSCAPE ATTRIBUTES AS CONTROLS ON GROITHD WATER NITRATE REMOVAL CAPACITY OF RIPARIAN ZONES,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2001Arthur J. Gold ABSTRACT: Inherent site factors can generate substantial variation in the ground water nitrate removal capacity of riparian zones. This paper examines research in the glaciated Northeast to relate variability in ground water nitrate removal to site attributes depicted in readily available spatial databases, such as SSUIRGO. Linking site-specific studies of riparian ground water nitrate removal to spatial data can help target high-value riparian locations for restoration or protection and improve the modeling of watershed nitrogen flux. Site attributes, such as hydric soil status (soil wetness) and geomorphology, affect the interaction of nitrate-enriched ground water with portions of the soil ecosystem possessing elevated biogeochemical transformation rates (i.e., biologically active zones). At our riparian sites, high ground water nitrate-N removal rates were restricted to hydric soils. Geomorphology provided insights into ground water flowpaths. Riparian sites located on outwash and organic/alluvial deposits have high potential for nitrate-enriched ground water to interact with biologically active zones. In till deposits, ground water nitrate removal capacity may be limited by the high occurrence of surface seeps that markedly reduce the time available for biological transformations to occur within the riparian zone. To fully realize the value of riparian zones for nitrate retention, landscape controls of riparian nitrate removal in different climatic and physiographic regions must be determined and translated into available spatial databases. [source] Self-reported antenatal adherence to medical treatment among pregnant women with Crohn's diseaseALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2010M. J. Nielsen Aliment Pharmacol Ther 2010; 32: 49,58 Summary Background, Adherence to medical treatment among women with Crohn's disease (CD) prior to and during pregnancy has never been reported. Aim, To examine both the predictors and prevalence rates of non-adherence to maintenance medical treatment among women with CD prior to and during pregnancy Methods, Among a population of 1.6 million inhabitants, we identified a total of 132 women with CD who had given birth during 2000,2005. Questionnaires were used to investigate predictors and extent of adherence. The validity of self-reported use of medication was assessed using data from the Danish Prescription Database. We used logistic regression to estimate prevalence odds ratios for non-adherence according to smoking status and other predictors. Results, Eighty percent of the patients returned the questionnaire. A total of 58 (54%) women reported to have been on medical treatment, 50 of whom had fulfilled a prescription on relevant medication. Adherence to medical treatment was 72%. Fear of a negative effect on fertility/foetus was a reason for non-adherence by 18.8% prior to, and by 45.5% during, pregnancy. Among smokers, 30.8% were non-adherent compared with 11.5% among nonsmokers (prevalence odds ratio 3.41, 95% CI 0.8,14.7). Conclusions, Despite fear of a negative effect on fertility/foetus, adherence to medical treatment is high in women with CD. There is no substantial variation in adherence prior to and during pregnancy. Smoking prior to pregnancy is a predictor of non-adherence. [source] Factors influencing Soay sheep survivalJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 4 2000E. A. Catchpole We present a survival analysis of Soay sheep mark recapture and recovery data. Unlike previous conditional analyses, it is not necessary to assume equality of recovery and recapture probabilities; instead these are estimated by maximum likelihood. Male and female sheep are treated separately, with the higher numbers and survival probabilities of the females resulting in a more complex model than that used for the males. In both cases, however, age and time aspects need to be included and there is a strong indication of a reduction in survival for sheep aged 7 years or more. Time variation in survival is related to the size of the population and selected weather variables, by using logistic regression. The size of the population significantly affects the survival probabilities of male and female lambs, and of female sheep aged 7 or more years. March rainfall and a measure of the North Atlantic oscillation are found to influence survival significantly for all age groups considered, for both males and females. Either of these weather variables can be used in a model. Several phenotypic and genotypic individual covariates are also fitted. The only covariate which is found to influence survival significantly is the type of horn of first-year female sheep. There is a substantial variation in the recovery probabilities over time, reflecting in part the increased effort when a population crash was expected. The goodness of fit of the model is checked by using graphical procedures. [source] Vasotocin and mesotocin in the brains of amphibians: State of the artMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2001Wilhelmus J.A.J. Smeets Abstract Immunohistochemical studies during the last decade have revealed elaborate systems of vasotocinergic (AVT) and mesotocinergic (MST) neuronal elements in the brain of a variety of amphibians including anurans, urodeles, and gymnophionans. Apart from a well-developed hypothalamo-hypophysial system, the antibodies demonstrated the existence of extrahypothalamic AVT- and MST-immunoreactive cell groups as well as extensive extrahypothalamic networks of immunoreactive fibers. The wide distribution of AVT- and MST-immunoreactive fibers throughout the brains of amphibians suggests that the two neuropeptidergic systems are involved not only in hypothalamo-hypophysial interactions, but also in a variety of other brain functions. Moreover, there is now evidence that sex-related differences occur in amphibians as previously shown for amniotes. It should be noted, however, that substantial variation occurs in the relative densities of AVT- and MST-immunoreactive fibers and number of cells between species, even within a single order of amphibians. Similar observations have been made in other classes of vertebrates and prompt us, therefore, to critically evaluate conclusions with respect to specific functions of AVT and MST in the central nervous system of vertebrates. Microsc. Res. Tech. 54:125,136, 2001. © 2001 Wiley-Liss, Inc. [source] Detection of QTLs for bread-making quality in wheat using a recombinant inbred line populationPLANT BREEDING, Issue 3 2009Y. Li Abstract Whereas gluten fraction accounts for 30,60% of the variation in wheat bread-making quality, there remains substantial variation determined by non-gluten factors. The objective of this study was to detect new loci for wheat quality. The genetics of sodium dodecyl sulphate-sedimentation volume (Ssd), grain hardness (GH), grain protein content, wet gluten content (WGC) and water absorption (Abs) in a set of 198 recombinant inbred lines derived from two commercial varieties was studied by quantitative trait loci (QTL) analysis. A genetic map based on 255 marker loci, consisting of 250 simple sequence repeat markers and five glutenin loci, Glu-A1, Glu-B1, Glu-D1, Glu-B3 and Glu-D3, was constructed. A total of 73 QTLs were detected for all traits. A major QTL for GH was detected on chromosome 1B and its relative contribution to phenotypic variation was 27.7%. A major QTL for Abs on chromosome 5D explained more than 30% of the phenotypic variation. Variations in Ssd were explained by four kinds of genes. Some QTLs for correlated traits mapped to the same regions forming QTL clusters or indicated pleiotropic effects. [source] Rhesus macaque milk: Magnitude, sources, and consequences of individual variation over lactationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Katherine Hinde Abstract Lactation represents the greatest postnatal energetic expenditure for mammalian mothers, and a mother's ability to sustain the costs of lactation is influenced by her physical condition. Mothers in good condition may produce infants who weigh more, grow faster, and are more likely to survive than the infants of mothers in poor condition. These effects may be partially mediated through the quantity and quality of milk that mothers produce during lactation. However, we know relatively little about the relationships between maternal condition, milk composition, milk yield, and infant outcomes. Here, we present the first systematic investigation of the magnitude, sources, and consequences of individual variation in milk for an Old World monkey. Rhesus macaques produce dilute milk typical of the primate order, but there was substantial variation among mothers in the composition and amount of milk they produced and thus in the milk energy available to infants. Relative milk yield value (MYV), the grams of milk obtained by mammary evacuation after 3.5,4 h of maternal-infant separation, increased with maternal parity and was positively associated with infant weight. Both milk gross energy (GE) and MYV increased during lactation as infants aged. There was, however, a trade-off; those mothers with greater increases in GE had smaller increases in MYV, and their infants grew more slowly. These results from a well-fed captive population demonstrate that differences between mothers can have important implications for milk synthesis and infant outcome. Am J Phys Anthropol 2009. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||