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Simple Correlation (simple + correlation)
Selected AbstractsEvaluating the contribution of soil properties to modifying lead phytoavailability and phytotoxicity,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Elizabeth A. Dayton Abstract Soil properties affect Pb bioavailability to human and ecological receptors and should be considered during ecological risk assessment of contaminated soil. We used path analysis (PA) to determine the relative contribution of soil properties (pH, organic C [OC], amorphous Fe and Al oxides [FEAL], and cation-exchange capacity [CEC]) in modifying Pb bioavailability. The response of biological endpoints (bioaccumulation and dry matter growth [DMG]) of lettuce (Lactuca sativa) grown on 21 Pb-spiked (2,000 mg/kg) soils were determined. Lettuce tissue Pb ranged from 3.22 to 233 mg/kg, and relative DMG ranged from 2.5 to 88.5% of their respective controls. Simple correlation showed strong relationships between CEC and OC (p < 0.01) and weaker relationships between pH and FEAL (p < 0.05) and Pb bioaccumulation. Results of PA suggest that soil pH increased the negative surface charge of organic matter and clay, thereby increasing CEC and decreasing Pb bioaccumulation. Also, the direct effect of OC on tissue Pb can be attributed to formation of surface Pb complexes by organic matter functional group ligands. Increased OC and/or CEC reduced Pb solubility and bioavailability in the 21 soils in the present study. The relative importance of soil properties likely will vary between studies employing different soils. Soil properties should be considered during the ecological risk assessment of metal in contaminated soils. Path analysis is useful for ecological studies involving soils with a wide range of physicochemical properties and can assist in site risk assessment of metals and remediation decisions on contaminated sites. [source] Increased neurogenesis and brain-derived neurotrophic factor in neurokinin-1 receptor gene knockout miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2003Sara Morcuende Abstract It has previously been shown that chronic treatment with antidepressant drugs increases neurogenesis and levels of brain-derived neurotrophic factor in the hippocampus. These changes have been correlated with changes in learning and long-term potentiation and may contribute to the therapeutic efficacy of antidepressant drug treatment. Recently, antagonists at the neurokinin-1 receptor, the preferred receptor for the neuropeptide substance P, have been shown to have antidepressant activity. Mice with disruption of the neurokinin-1 receptor gene are remarkably similar both behaviourally and neurochemically to mice maintained chronically on antidepressant drugs. We demonstrate here that there is a significant elevation of neurogenesis but not cell survival in the hippocampus of neurokinin-1 receptor knockout mice. Neurogenesis can be increased in wild-type but not neurokinin-1 receptor knockout mice by chronic treatment with antidepressant drugs which preferentially target noradrenergic and serotonergic pathways. Hippocampal levels of brain-derived neurotrophic factor are also two-fold higher in neurokinin-1 receptor knockout mice, whereas cortical levels are similar. Finally, we examined hippocampus-dependent learning and memory but found no clear enhancement in neurokinin-1 receptor knockout mice. These data argue against a simple correlation between increased levels of neurogenesis or brain-derived neurotrophic factor and mnemonic processes in the absence of increased cell survival. They support the hypothesis that increased neurogenesis, perhaps accompanied by higher levels of brain-derived neurotrophic factor, may contribute to the efficacy of antidepressant drug therapy. [source] Hydro-meteorological variability in the greater Ganges,Brahmaputra,Meghna basinsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2004MD. Rashed Chowdhury Abstract The flows of the Ganges, Brahmaputra and Meghna (GBM) are highly seasonal, and heavily influenced by monsoon rainfall. As a result, these rivers swell to their banks and often overflow during the monsoon months. This is most pronounced in the downstream regions, particularly in Bangladesh, which is the lowest riparian country. The objective of this paper is to study this hydro-meteorological variability in the greater GBM regions, including the headwater regions in India and their role in streamflows in Bangladesh, and explore the large-scale oceanic factors affecting this hydro-meteorological variability. Global precipitation data, Bangladesh rainfall and streamflow records have been analysed and related to large-scale climate patterns, including upstream rainfall, regional atmospheric circulation and patterns of sea-surface temperature. The findings have quantified how the streamflows of these rivers in Bangladesh are highly correlated with the rainfall in the upper catchments with typically a lag of about 1 month. Therefore, streamflows in Bangladesh could be reasonably estimated for 1 to 3 months in advance (especially for the Ganges and Brahmaputra rivers) by employing simple correlation, if rainfall data from countries further up are available on a real-time and continuous basis. In the absence of rainfall data, streamflow forecasts are still possible from unusually warm or cold sea-surface temperatures in the tropics. The study concludes that hydro-meteorological information flow between Bangladesh and other neighbouring countries is essential for developing a knowledge base for evaluating the potential implications of seasonal streamflow forecast in the GBM basins in Bangladesh. Copyright © 2004 Royal Meteorological Society [source] Explaining bird species composition and richness in eucalypt-dominated remnants in subhumid TasmaniaJOURNAL OF BIOGEOGRAPHY, Issue 9 2003Michael A. MacDonald Abstract Aim To determine the factors influencing the distribution of birds in remnants in a fragmented agricultural landscape. Location Forty-seven eucalypt remnants and six sites in continuous forest in the subhumid Midlands region of Tasmania, Australia. Methods Sites were censused over a two-year period, and environmental data were collected for remnants. The avifauna of the sites was classified and ordinated. The abundances of bird species, and bird species composition, richness, abundance and diversity were related to environmental variables, using simple correlation and modelling. Results There were two distinct groups of sample sites, which sharply differed in species composition, richness, diversity and bird abundance, separated on the presence/absence of noisy miner (Manorina melanocephala Latham) colonies, remnant size, vegetation structural attributes and variables that reflected disturbance history. The approximate remnant size threshold for the change from one group to another was 20,30 ha. Remnant species richness and diversity were most strongly explained by remnant area and noisy miner abundance, with contributions from structural and isolation attributes in the second case. Segment richness was explained by precipitation, logging history and noisy miner abundance. Bird abundance was positively related to precipitation and negatively related to tree dieback. The 28 individual bird species models were highly individualistic, with vegetation structural variables, noisy miner abundance, climatic variables, variables related to isolation, area, variables related to floristics, disturbance variables, the nature of the matrix and remnant shape all being components in declining order of incidence. Age of the remnant did not relate to any of the dependent variables. Main conclusions Degraded and small remnants may have become more distinct in their avifaunal characteristics than might otherwise be the case, as a result of the establishment of colonies of an aggressive native bird, the noisy miner. The area, isolation and shape of remnants directly relate to the abundance of relatively few species, compared to vegetation attributes, climate and the abundance of the noisy miner. The nature of the matrix is important in the response of some species to fragmentation. [source] Genetic and phenotypic diversity of echovirus 30 strains and pathogenesis of type 1 diabetesJOURNAL OF MEDICAL VIROLOGY, Issue 7 2007A. Paananen Abstract Several enterovirus serotypes should be considered as potentially diabetogenic. The capacity of an enterovirus to kill or impair the functions of human ,-cells can vary among the strains within a given serotype as shown previously for echovirus 9 and 30 (E-30). The evolution of E-30 has also shown patterns correlating with the global increase of type 1 diabetes incidence. In the present study, antigenic properties of a set of E-30 isolates were investigated and the results correlated with the previously documented ,-cell destructive phenotype of the strains, or to genetic clustering of the strains. No simple correlation between the three properties was observed. A full-length infectious clone was constructed and sequenced from one of the isolates found to be most destructive to ,-cells (E-30/14916net87). Phylogenetic analyses demonstrated that this strain was closely related to the E-30 prototype strain at the capsid coding region while outside the capsid region prototype strains of several other human enterovirus B serotypes clustered more closely. This suggests that the relatively greater pathogenicity of the strain might be based on properties of the genome outside of the structural protein coding region. Neutralizing antibody assays on sera from 100 type 1 diabetic patients and 100 controls using three different E-30 strains did not reveal differences between the groups. This finding does not support a previous proposition of aberrant antibody responses to E-30 in diabetic patients. It is concluded that identification of the genetic counterparts of pathogenicity of E-30 strains requires further studies. J. Med. Virol. 79:945-955, 2007. © 2007 Wiley-Liss, Inc. [source] Excessive daytime sleepiness in patients suffering from different levels of obstructive sleep apnoea syndromeJOURNAL OF SLEEP RESEARCH, Issue 3 2000Sauter Excessive daytime sleepiness (EDS) is a frequent symptom of patients with obstructive sleep apnoea (OSA). EDS is a high-risk factor for accidents at work and on the road. Thirty untreated patients with different levels of severity of OSA were studied concerning night sleep and EDS. The criterion for severity was the respiratory disturbance index (RDI): 15 patients were classified as ,moderately' apnoeic (RDI < 40), 15 as ,severely' apnoeic (RDI > 40). Following night-time polysomnography, objective and subjective aspects of EDS were studied. To assess objective EDS the Maintenance of Wakefulness Test (MWT) and a computer-based vigilance performance test were used. Subjective EDS was determined using the Stanford Sleepiness Scale (SSS), the Epworth Sleepiness Scale (ESS) and the Visual Analogue Scales for Performance (VAS-P) and Tiredness (VAS-T). Well-being was assessed using the Scale of Well-Being by von Zerssen (Bf-S/Bf-S,). Severe apnoea patients spent more time in stage 1 and less in slow-wave sleep. MWT latencies tended to be shorter in the severe apnoea group. Vigilance testing revealed no group differences. Patients with moderate apnoea described themselves as more impaired in all subjective scales, but only SSS scores reached statistical significance. Our results suggest that there is no simple correlation between polysomnographic and respiratory sleep variables at night on the one hand, and the extent of EDS on the other hand. Furthermore, subjective and objective evaluation of EDS does not yield the same results. New approaches which allow a more detailed analysis of night sleep and daytime function are required to identify high-risked patients. [source] Function in Escherichia coli of the non-catalytic part of RNase E: role in the degradation of ribosome-free mRNAMOLECULAR MICROBIOLOGY, Issue 5 2002Anne Leroy Summary RNase E contains a large non-catalytic region that binds RNA and the protein components of the Escherichia coli RNA degradosome. The rne gene was replaced with alleles encoding deletions in the non-catalytic part of RNase E. All the proteins are stable in vivo. RNase E activity was tested using a PT7,lacZ reporter gene, the message of which is particularly sensitive to degradation because translation is uncoupled from transcription. The non-catalytic region has positive and negative effectors of mRNA degradation. Disrupting RhlB and enolase binding resulted in hypoactivity, whereas disrupting PNPase binding resulted in hyperactivity. Expression of the mutant proteins in vivo anticorrelates with activity showing that autoregulation compensates for defective function. There is no simple correlation between RNA binding and activity in vivo. An allele (rne131), expressing the catalytic domain alone, was put under Plac control. In contrast to rne+, low expression of rne131 severely affects growth. Even with autoregulation, all the mutants are less fit when grown in competition with wild type. Although the catalytic domain of RNase E is sufficient for viability, our work demonstrates that elements in the non-catalytic part are necessary for normal activity in vivo. [source] Climate mediated exogenous forcing and synchrony in populations of the oak aphid in the UKOIKOS, Issue 2 2009Sergio A. Estay Contemporary population dynamics theory suggests that animal fluctuations in nature are the result of the combined forces of intrinsic and exogenous factors. Weather is the iconic example of an exogenous force. The common approach for analyzing the relationship between population size and climatic variables is by simple correlation or using the climate as an additive covariable in statistical models. Here, we evaluated different functional forms in which climatic variables could influence population dynamics of the oak aphid Tuberculatus annulatus both in each locality and in relation to synchrony between localities. Results indicate that in at least four of eight aphid populations, climate influences population dynamics by modifying the carrying capacity of the system (lateral effect mediated by winter precipitation). Additionally, path analysis showed that synchrony in population dynamics is highly correlated with synchrony in winter precipitation regime, and the spatial scale of both processes is similar, which suggests that this is an example of the Moran effect. Our results show the key effects of precipitation on intra and inter population processes of this aphid. The methods used, mixing population dynamics modelling and test of synchrony, allowed us to connect the direct and indirect effects of exogenous variables into each population with patterns of synchrony inter populations. [source] Mechanisms of lymphatic metastasis in human colorectal adenocarcinoma,THE JOURNAL OF PATHOLOGY, Issue 5 2009Daniel Royston Abstract The invasion of lymphatic vessels by colorectal cancer (CRC) and its subsequent spread to draining lymph nodes is a key determinant of prognosis in this common and frequently fatal malignancy. Although tumoural lymphangiogenesis is assumed to contribute to this process, review of the current literature fails to support any notion of a simple correlation between lymphatic vessel density and CRC metastasis. Furthermore, attempts to correlate the expression of various lymphangiogenic growth factors, most notably VEGF-C and VEGF-D, with the lymphatic metastasis of CRC have provided contradictory results. Recent evidence from animal and human models of tumour metastasis suggests that complex functional and biochemical interactions between the microvasculature of tumours and other cell types within the tumour microenvironment may play a pivotal role in the behaviour of commonly metastasizing tumours. Indeed, previous insights into tumoural blood vessels have provided candidate markers of tumoural angiogenesis that are currently the subject of intense investigation as future therapeutic targets. In this review article we survey the current evidence relating lymphangiogenesis and lymphangiogenic growth factor production to metastasis by CRC, and attempt to provide some insight into the apparent discrepancies within the literature. In particular, we also discuss some new and provocative insights into the properties of tumoural lymphatics suggesting that they have specific expression profiles distinct from those of normal lymphatic vessels and that appear to promote metastasis. These findings raise the exciting prospect of future biomarkers of lymphatic metastasis and identify potential targets for new generation anti-tumour therapies. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Allometry and biomass distribution in replanted mangrove plantations at Gazi Bay, KenyaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2009J. G. Kairo Abstract 1.This study reports above-ground biomass of 5 and 8 years old mangrove plantations in Kenya. Trees with stem diameter greater than 5.0,cm inside 100,m2 sample plots were harvested, and then separated into stems (trunks), branches, leaves and prop roots. 2.Mean above-ground biomass was calculated at 20.25 t dry matter ha,1 for Rhizophora mucronata Lam., 11.7 t dry matter ha,1 for Avicennia marina (Forsk.) Vierh., 6.7 t dry matter ha,1 for Sonneratia alba Sm. and 3.7 t dry matter ha,1 for Ceriops tagal (Perr.) C. B. Robinson. In A. marina and R. mucronata, stems (52.19%) and prop-roots (30.28%), respectively, accounted for the highest proportion of the above-ground dry weight. While in S. alba and C. tagal, branch biomass represented the highest percentage of biomass, 48.20% and 43.62%, respectively. 3.The total above-ground biomass of R. mucronata was best estimated from regression equations using a combination of height and diameter above stilt root as the independent variables. For A. marina, C. tagal and S. alba there was no simple correlation found between the above-ground biomass and tree height or stem diameter. 4.Comparison of the regression models with those developed elsewhere gave different biomass values in these plots, further reinforcing the need for the use of site-specific allometric equations for biomass estimation. Copyright © 2009 John Wiley & Sons, Ltd. [source] Simplified models for the performance evaluation of desiccant wheel dehumidificationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2003M. Beccali Abstract In the present communication, simple models have been presented to evaluate the performance of rotary desiccant wheels based on different kind of solid desiccants e.g. silica gel and LiCl. The first part of the paper presents ,Model 54' which is developed for silica gel desiccant rotor. The model has been derived from the interpolation of experimental data obtained from the industry and the correlations have been developed for predicting outlet temperature and absolute humidity. The ,Model 54' consists of 54 coefficients corresponding to each correlation for outlet absolute humidity and temperature and it is found that the model predicts very well the performance of silica gel desiccant rotor (Type-I). In the second part of the paper, a psychrometric model has been presented to obtain relatively simple correlations for outlet temperature and absolute humidity. The developed psychometric model is based on the correlations between the relative humidity and enthalpy of supply and regeneration air streams. The model is used to predict the performance of three type of desiccant rotors manufactured by using different kind of solid desiccants (Type I, II and III). The model is tested corresponding to a wide range of measurement data. The developed psychometric model is simple in nature and able to predict very well the performance of different kind of desiccant rotors. Copyright © 2002 John Wiley & Sons, Ltd. [source] Correlations between physiology and lifespan , two widely ignored problems with comparative studiesAGING CELL, Issue 4 2005John R. Speakman Summary Comparative differences between species provide a powerful source of information that may inform our understanding of the aging process. However, two problems regularly attend such analyses. The co-variation of traits with body mass is frequently ignored, along with the lack of independence of the data due to a shared phylogenetic history. These problems undermine the use of simple correlations between various factors and maximum lifespan potential (MLSP) across different species as evidence that the factors in question have causal effects on aging. Both of these problems have been widely addressed by comparative biologists working in fields other than aging research, and statistical solutions to these issues are available. Using these statistical approaches, of making analyses of residual traits with the effects of body mass removed, and deriving phylogenetically independent contrasts, will allow analyses of the relationships between physiology and maximum lifespan potential to proceed unhindered by these difficulties, potentially leading to many useful insights into the aging process. [source] X-ray active galactic nuclei in the core of the Perseus clusterMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2007S. Santra ABSTRACT We present a study of the X-ray emission from the nuclei of galaxies observed in the core of the Perseus cluster in a deep exposure with Chandra. Point sources are found coincident with the nuclei of 13 early-type galaxies, as well as the central galaxy NGC 1275. This corresponds to all galaxies brighter than MB > ,18 in the Chandra field. All of these sources have a steep power-law spectral component and four have an additional thermal component. The unabsorbed power-law luminosities in the 0.5,7.0 keV band range from 8 × 1038 to 5 × 1040 erg s,1. We find no simple correlations between the K -band luminosity, or the FUV and NUV AB magnitudes of these galaxies and their X-ray properties. We have estimated the black hole masses of the nuclei using the K -band MBH,LKbol relation and again find no correlation between black hole mass and the X-ray luminosity. Bondi accretion on to the black holes in the galaxies with minihaloes should make them much more luminous than observed. [source] Environmental factors and population fluctuations of Akodon azarae (Muridae: Sigmodontinae) in central ArgentinaAUSTRAL ECOLOGY, Issue 2 2009VERÓNICA ANDREO Abstract The aim of this work was to explore the relationship between population density of Akodon azarae (Muridae: Sigmodontinae) and climatic and environmental variables, and determine which of them are associated to within and among-year changes in rodent abundance in agro-ecosystems from south Córdoba, Argentina. The study was carried out in a rural area of central Argentina, from 1983 to 2003. Density was estimated as a relative density index (RDI). Temperature, precipitation and humidity were obtained from records of the National University of Rio Cuarto. Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature were recorded from National Oceanic and Atmospheric Administration (1983,1998) and Landsat (1998,2003) imagery data sets. We performed simple correlations, multiple regressions and distributed lag analysis. Direct association of climatic and environmental variables with RDI was in general, low. The amount of variability in seasonal changes in density explained by climatic and environmental variables altogether varied from 10% to 70%. Seasonal population fluctuations were influenced by NDVI and rainfall with one and two seasons of delay. Autumn maximum density of the species was also associated with vegetation and rainfall of previous seasons. There also seemed to be an indirect influence of rainfall through vegetation given that we found a positive correlation between them. Results were consistent with basic aspects of the ecology of the species, such as its strong preference for highly covered areas, which provide food and protection from predators, likely increasing its reproductive success. Therefore, in the rural area central Argentina, A. azarae showed seasonal fluctuations with delayed influence of rainfall and vegetation and indirect effects of rainfall. [source] Estudio Fenológico de Cactíceas en el Enclave Seco de la Tatacoa, Colombia,BIOTROPICA, Issue 3 2000Adriana Ruiz RESUMEN Durance un año se realizó el estudio fenológico de tres cactáceas columnares Stenocereus griseus (Haw.) Britton & Rose, Pilosocereus sp., Cereus hexagonus (L.) Mill., y una cactácea decumbente, Monvillea cf. smithiana (Britton & Rose) Backeberg., en el enclave seco interandino de La Tatacoa, Colombia. Los polinizadores y/o dispersores de las cactáceas fueron capturados mensualmente y se recolectaron las muestras fecales para la identificatión de los granos de polen y las semillas de los frutos consumidos. La floración de todas las especies fue prolongada y mostraron patrones bimodales, multimodales, o irregulares. La fructificación en todas las especies también se extendió durante todo el año, con un desfase de dos meses con respecto a la floración. Aunque no se encontró una correlatión significativa entre los valores mensuales de precipitatión y la producción de flores y frutos, la floración durante la época seca fue mayor en S. griseus, mientras que Pilosocereus sp. y C. hexagonus mostraron los valores más altos durante la época de lluvias. La productión de frutos también fue estacional, con un incremento durante la época de lluvias para S. griseus y C. hexagonus. La floración y fructificatión en M. cf. smithiana no mostraron diferencias significativas entre la época seca y la lluviosa. Los murciélagos Glossophaga longirostris, Carollia perspicillata, Sturnira lilium y algunas aves como Melanerpes rubricapillus (Picidae) y Mimus gilvus (Mimidae), y una mariposa nocturna (Sphingidae), fueron algunos de los polinizadores y/o consumidores de estas especies de cactáceas. ABSTRACT A one-year phenological study of three columnar cacti, Stenocereus griseus (Haw.) Britton & Rose, Pilosocereus sp., Cereus hexagonus (L.) Mill., and a decumbent cactus Monvillea cf. smithiana (Britton & Rose) Backeberg., was carried out in the Andean arid region of La Tatacoa, Colombia. Pollinators and/or dispersers of the cacti species also were studied monthly, and fecal samples were collected for the identification of pollen and seeds. The flowering of all species was prolonged and showed bimodal, multimodal, or irregular patterns. Fruiting in all species also was prolonged and followed flowering with a lag of less than two months. Although there were no simple correlations between rainfall and flowering or fruiting, flower production during the dry season was higher for 5. griseus, while Pilosocereus sp. and C. hexagonus showed higher flower production during the wet season. Fruit production was also seasonal, with higher production during the wet season for 5. griseus and C. hexagonus. The patterns of flowering and fruiting in M. cf. smithiana showed no relationships with dry and wet seasons. The bats Glossophaga longirostris, Carollia perspicillata, Sturnira lilium, the birds Melanerpes rubricapillus (Picidae) and Mimus gilvus (Mimidae), and moths of the family Sphingidae, were identified as pollinators and/or fruit consumers of these cacti species. [source] | |||||||||||||