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Favourable Conditions (favourable + condition)
Selected AbstractsGeology and the London UndergroundGEOLOGY TODAY, Issue 1 2009Jonathan D. Paul Geology as a whole is the main influence on determining the feasibility of tunnelling for underground railways, and at what cost. Favourable conditions encouraged the early development of a network, significantly alter the methods used for construction, and are what form the tunnels, in terms of horizontal and vertical alignment. Local geology is shown, by means of two cross-sections following the tunnels, to be more important than the overall regional geology, where the underlying strata exhibit pronounced variations in permeability, and so mechanical properties. Geological complexities specific to the area of tunnelling generate problems during construction, but lead to technological innovation in the long term and a better understanding of local stratigraphy. As the result of this, and the increase in the quality of preliminary surveys, we are increasingly able to tunnel in areas previously considered treacherous. [source] A finite element analysis of ferrule design on restoration resistance and distribution of stress within a rootINTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2006I. Ichim Abstract Aim, To analyse the effect of ferrule height upon the mechanical resistance and stress distribution within a root to explain variations in the pattern of root fracture. Methodology, An extracted, intact, caries free, maxillary right central incisor was scanned by laser and then reconstructed on a computer to produce a model of the tooth and associated periodontal ligament. A simulated post/core/crown restoration was constructed on conventional tooth preparations with various ferrules. The crown was loaded with a simulated 500 N force and the simulated displacement of components and the tensile and compressive stress within the tooth structure were recorded. Results, Without a ferrule preparation, the simulated crown tilted to the labial and rotated distally. With increasing ferrule height the displacement and rotation of the crown reduced in conventional and crown-lengthening models with maximum reduction occurring when the ferrule height reached 1.5 mm. In ferrule models, higher levels of tensile stress developed in internal (by a factor of 8) and mid-root palatal (by a factor of 90) dentine at the cervical margin of the preparation. With an increase in ferrule height, the area of tensile stress within the palatal mid-dentine expanded towards the cervical margin. Similar patterns and stress values were recorded for the crown-lengthening models. Conclusion, The study confirms that a ferrule increases the mechanical resistance of a post/core/crown restoration. However a ferrule creates a larger area of palatal dentine under tensile stress that may be a favourable condition for a crack to develop. Crown-lengthening did not alter the levels or pattern of stress within compared with conventional ferrule preparations. [source] Acid,base balance in sea bass (Dicentrarchus labrax L.) in relation to water oxygen concentrationAQUACULTURE RESEARCH, Issue 12 2003S Cecchini Abstract The influence of water oxygen concentration on the acid,base balance of sea bass was evaluated. Fish weighing 200,250 g were cultured under different dissolved oxygen concentrations of 64%, 97%, 150% and 250% saturation (92.7, 140.5, 217.5 and 362.7 mmHg respectively) under mild hypoxia, normoxia, mild hyperoxia and high hyperoxia conditions. The results showed that high hyperoxia and mild hypoxia conditions modified some blood parameters significantly when compared with fish held under the normoxia condition, while no differences were shown with respect to the acid,base balance of fish cultured under normoxia and mild hyperoxia conditions. This testifies that the mild hyperoxia condition does not produce physiological disturbances in the acid,base status of sea bass and it could be considered a favourable condition in sea bass land-based farming, mainly in comparison with the mild hypoxia condition, responsible for other physiological problems. [source] Establishing survey and monitoring protocols for the assessment of conservation status of fish populations in river Special Areas of Conservation in the UKAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2009I.G. Cowx Abstract 1.Under the EC Habitats Directive (92/43/EEC), several rivers in the UK have been designated Special Areas of Conservation (SACs) because they support important populations of fish species. Several factors need to be considered when establishing survey protocols to assess the conservation status of fish species in these rivers. 2.It is important to understand the biology and habitat requirements of fish species and to design appropriate monitoring surveys that adequately assess the status of the fish populations. This information can, in turn, provide the basis for establishing sustainable conservation targets for specific stocks, a process known as condition assessment. 3.Favourable condition of fish species in SAC rivers is assessed using three criteria. The first relates to density of fish in various life stages against pre-set targets, assuming that an appropriate number of sites is surveyed to account for natural spatial and temporal variations in fish populations. The second is evaluation of the demographic structure to demonstrate continued recruitment success. Third, by mapping the distribution of the target species in individual rivers and where favourable condition is only achieved where there has been no reduction in the distribution range river between surveys. 4.The framework described was developed from limited survey data. As more monitoring and assessment data become available, the threshold criteria for favourable condition for each species should be improved, and uncertainty in the procedures reduced. Copyright © 2008 John Wiley & Sons, Ltd. [source] Long-term, retrospective evaluation (implant and patient-centred outcome) of the two-implant-supported overdenture in the mandible.CLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2010Part 2: marginal bone loss Abstract Objective: In part 2 of this long-term, retrospective study on the two-implant-supported overdenture in the mandible, the annual marginal bone loss was evaluated in detail and parameters, with a significant effect on the annual bone loss, were verified. Material and methods: For all 495 patients with an overdenture in the mandible at least 5 years in function, data up to their last follow-up visit had been collected, including long-cone radiographs (taken at the abutment connection and after years 1, 3, 5, 8, 12 and 16 of loading) and probing data at their last evaluation. General information (medical history, implant data, report on surgery) was retrieved from the patient's file. Two hundred and forty-eight patients had been clinically examined recently. For the others, information on bone level and probing depths were retrieved from the patient's files, as all patients had been enrolled in our annual follow-up schedule. Results: The mean annual bone loss on a site level (without considering the first year of bone remodelling) after 3 years of loading was 0.08 mm/year (SD=0.22, n=1105), after 5 years of loading 0.07 mm/year (SD=0.14, n=892), after 8 years of loading 0.06 mm/year (SD=0.12, n=598), after 12 years 0.04 mm/year (SD=0.07, n=370) and 0.05 mm/year (SD=0.05, n=154) after 16 years of loading. Ongoing bone loss was seen in a number of implants (n=26) with the annual bone loss exceeding 0.2 mm. Some factors clearly showed a significant impact on bone loss: smoking (,10 cigarettes/day), GBR, the presence of dehiscence and bone quantity(the latter only during the first year). The probing data showed a favourable condition, with <1.2% of the approximal pockets being ,6 mm, and 4.1%=5 mm. Conclusions: The mean annual bone loss over the study period was <0.1 mm/year after the first year of loading. However, a small number (2.5%) of the implants showed continuing bone loss. To cite this article: Vercruyssen M, Quirynen M. Long-term, retrospective evaluation (implant and patient-centred outcome) of the two-implants-supported overdenture in the mandible. Part 2: marginal bone loss. Clin. Oral Impl. Res. 21, 2010; 466,472. doi: 10.1111/j.1600-0501.2009.01902.x [source] Antagonistic effects of seed dispersal and herbivory on plant migrationECOLOGY LETTERS, Issue 3 2006Mark Vellend Abstract The two factors that determine plant migration rates , seed dispersal and population growth , are generally treated independently, despite the fact that many animals simultaneously enhance plant migration rate via seed dispersal, and decrease it via negative effects of herbivory on population growth. Using extensive empirical data, we modelled the antagonistic effects of seed dispersal and herbivory by white-tailed deer on potential migration rates of Trillium grandiflorum, a forest herb in eastern North America. This novel antagonistic interaction is illustrated by maximum migration rates occurring at intermediate, but low herbivory (< 15%). Assuming herbivory < 20% and favourable conditions for population growth during post-glacial migration, seed dispersal by deer can explain rates of migration achieved in the past, in contrast to previous models of forest herb migration. However, relatively unfavourable conditions for population growth and increasingly intense herbivory by deer may compromise plant migration in the face of present and future climate change. [source] Resting spore formation of aphid-pathogenic fungus Pandora nouryi depends on the concentration of infective inoculumENVIRONMENTAL MICROBIOLOGY, Issue 7 2008Zhi-Hong Huang Summary Resting spore formation of some aphid-pathogenic Entomophthorales is important for the seasonal pattern of their prevalence and survival but this process is poorly understood. To explore the possible mechanism involved in the process, Pandora nouryi (obligate aphid pathogen) interacted with green peach aphid Myzus persicae on cabbage leaves under favourable conditions. Host nymphs showered with primary conidia of an isolate (LC50: 0.9,6.7 conidia mm,2 4,7 days post shower) from air captures in the low-latitude plateau of China produced resting spores (azygospores), primary conidia or both spore types. Surprisingly, the proportion of mycosed cadavers forming resting spores (Pcfrs) increased sharply within the concentrations (C) of 28,240 conidia mm,2, retained high levels at 240,1760, but was zero or extremely low at 0.3,16. The Pcfrs,C relationship fit well the logistic equation Pcfrs = 0.6774/[1 + exp(3.1229,0.0270C)] (r2 = 0.975). This clarified for the first time the dependence of in vivo resting spore formation of P. nouryi upon the concentration of infective inoculum. A hypothesis is thus proposed that some sort of biochemical signals may exist in the host,pathogen interaction so that the fungal pathogen perceives the signals for prompt response to forthcoming host-density changes by either producing conidia for infecting available hosts or forming resting spores for surviving host absence in situ. [source] GROWTH OF CRUSTOSE LICHENS: A REVIEWGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2010RICHARD ARMSTRONG ABSTRACT. Crustose species are the slowest growing of all lichens. Their slow growth and longevity, especially of the yellow-green Rhizocarpon group, has made them important for surface-exposure dating (lichenometry). This review considers various aspects of the growth of crustose lichens revealed by direct measurement including: 1) early growth and development; 2) radial growth rates (RGR, mm yr,1); 3) the growth rate,size curve; and 4) the influence of environmental factors. Many crustose species comprise discrete areolae that contain the algal partner growing on the surface of a non-lichenized fungal hypothallus. Recent data suggest that ,primary' areolae may develop from free-living algal cells on the substratum while ,secondary' areolae develop from zoospores produced within the thallus. In more extreme environments, the RGR of crustose species may be exceptionally slow but considerably faster rates of growth have been recorded under more favourable conditions. The growth curves of crustose lichens with a marginal hypothallus may differ from the ,asymptotic' type of curve recorded in foliose and placodioid species; the latter are characterized by a phase of increasing RGR to a maximum and may be followed by a phase of decreasing growth. The decline in RGR in larger thalli may be attributable to a reduction in the efficiency of translocation of carbohydrate to the thallus margin or to an increased allocation of carbon to support mature ,reproductive' areolae. Crustose species have a low RGR accompanied by a low demand for nutrients and an increased allocation of carbon for stress resistance; therefore enabling colonization of more extreme environments. [source] Effects of Grazing on Bituminaria bituminosa (L) Stirton: A Potential Forage Crop in Mediterranean GrasslandsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2006M. Sternberg Abstract Plant traits of Bituminaria bituminosa, as affected by different intensities of cattle grazing, were studied in a Mediterranean grassland in Israel. B. bituminosa is a widespread Mediterranean perennial legume species that may potentially serve as a fodder crop in Mediterranean grasslands. The aims of the present study were: (i) to evaluate the responses of B. bituminosa to different cattle grazing intensities; (ii) to study functional traits associated with grazing tolerance; and (iii) to evaluate its potential as an alternative forage crop in the region. A total of 100 B. bituminosa plants were monitored in field conditions. During the growing season each individual was sampled five times and the following plant traits were monitored each time: (i) aboveground biomass production, (ii) plant height, (iii) specific leaf area (SLA), (iv) number of flowers, (v) seed mass and size, (vi) tannin concentration in leaves, (vii) total nitrogen in leaves, (viii) fibre concentration in leaves (Neutral Detergent Fiber), and (ix) in vitro dry matter digestibility. The results showed that grazing intensity and history of grazing affected B. bituminosa performance. Plant biomass, height, and flower and seed production were all reduced when plants were exposed to cattle grazing. However, under moderate grazing intensities, its plant cover remained relatively stable indicating a potential tolerance under this stocking rate. The nutritious characteristics of B. bituminosa leaves were good, and the condensed tannins concentration found indicated favourable conditions for digestion. Moreover, the in vitro digestibility studies indicated relatively high values (46,51 %) of digestion. B. bituminosa may be considered as a potential crop for cattle feeding in Mediterranean grasslands. Growing this plant in dense stands in rotational paddocks may provide alternative sources of natural fodder protein, reducing the potential costs of artificial feed supplements. [source] Effect of Different Levels of Wheat Straw Soil Surface Coverage on Weed Flora in Vicia faba CropsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2003D. Bilalis Abstract The crop system implemented on organic farms requires that crop residues are incorporated into the soil following the end of wheat cultivation. This system leads to a reduction in soil moisture and the creation of favourable conditions for the emergence of weeds. In contrast, covering the soil with 60 % crop residues was found to maintain soil moisture and lead to a reduction in dry weed mass, population density and population frequency as well as a reduction in population diversity, regardless of the initial weed flora before the implementation of different soil tillage systems. Finally, an increase in the prevalence of broad-leafed weeds was observed as the level of soil cover increased. [source] Sexual vs. asexual reproduction in an ecosystem engineer: the massive coral Montastraea annularisJOURNAL OF ANIMAL ECOLOGY, Issue 2 2007NICOLA L. FOSTER Summary 1Long-lived sedentary organisms with a massive morphology are often assumed to utilize a storage effect whereby the persistence of a small group of adults can maintain the population when sexual recruitment fails. However, employing storage effects could prove catastrophic if, under changing climatic conditions, the time period between favourable conditions becomes so prolonged that the population cannot be sustained solely be sexual recruitment. When a species has multiple reproductive options, a rapidly changing environment may favour alternative asexual means of propagation. 2Here, we revisit the importance of asexual dispersal in a massive coral subject to severe climate-induced disturbance. Montastraea annularis is a major framework-builder of Caribbean coral reefs but its survival is threatened by the increasing cover of macroalgae that prevents settlement of coral larvae. 3To estimate levels of asexual recruitment within populations of M. annularis, samples from three sites in Honduras were genotyped using four, polymorphic microsatellite loci. 4A total of 114 unique genets were identified with 8% consisting of two or more colonies and an exceptionally large genet at the third site comprising 14 colonies. 5At least 70% of multicolony genets observed were formed by physical breakage, consistent with storm damage. 6Our results reveal that long-lived massive corals can propagate using asexual methods even though sexual strategies predominate. [source] Enumeration of Campylobacter spp. on the surface and within chicken breast filletsJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2007P. Luber Abstract Aim:, To investigate how many Campylobacter bacteria are present on the surface and inside chicken breast fillets, with a focus on generating data distributions which can be used in risk assessments for this pathogen,commodity combination. Methods and Results:, We analysed 100 fresh retail chicken breast fillets (skinless and deboned) by means of a rinse sample for surface and 55 fillets for internal pathogen contamination using 10 g meat and a most probable number technique. Prevalence was 87% on the surface and 20% in the deep tissue. The mean number of Campylobacter on the surface of the fillets was 1903 CFU, with a median of 537 CFU and a maximum of 38 905 CFU. Campylobacter counts inside the tissue were <1 CFU g,1 meat (mean = 0·24 CFU, median = 0·15 CFU, maximum = 0·74 CFU). In addition, we investigated the influence of the type of package on the occurrence of the pathogen. Data provide an indication of less favourable conditions for survival of the pathogen on chicken meat packed under a modified atmosphere of carbon dioxide in nitrogen, in comparison with ambient air or vacuumed packages. Conclusions:, Given the high numbers of the pathogen on the chicken meat surface in comparison with low levels of internal contamination, it can be concluded that cross-contamination during the preparation of contaminated chicken is a more important pathway for consumers' exposure to Campylobacter than the consumption of undercooked meat. Significance and Impact of the Study:, The detailed quantitative data on the occurrence of C. jejuni and C. coli on the surface and inside chicken meat presented here can be useful for future probabilistic exposure assessments. [source] What youngsters say about adults: seedling roots reflect clonal traits of adult plantsJOURNAL OF ECOLOGY, Issue 3 2007MARIE, MILAUEROVÁ Summary 1Grime's theory on plant strategies predicts that the set of traits present in established plants is not correlated with that found in the regenerative stage of the life cycle. We tested this prediction and further investigated whether clonal growth traits, which are found in adult plants but also affect regeneration, are correlated with seedling traits. 2We characterized seedling root systems by their total length, number of root tips and several architectural parameters (length of exterior and interior root links and two topological indices). These below-ground traits were supplemented by the ratio of leaf area to root length, representing relative investment into photosynthesizing surface. We compared seedling traits with clonal growth traits, adult plant heights, and species positions on gradients of nitrogen and water availability. 3Plant species with limited horizontal spread by clonal growth exhibited a larger relative investment in photosynthetic area and also developed larger root systems as seedlings. 4Seedlings of species with taller shoots and those which occur naturally at nutrient-rich sites developed both larger roots and more dichotomously branched root systems (with higher total length and more branches). 5Taking phylogenetic inertia into account showed that this explained large parts of the variation in seedling traits. Relationships between clonal spread and seedling traits were strengthened by phylogenetic correction. 6Our study shows that some of the traits of clonal growth affect both the established and the regenerative stages of the life cycle, suggesting that an evolutionary trade-off exists between the ability to spread clonally and performance at the seedling stage. Species not able to escape from less favourable conditions by extensive clonal spread seem to be more able to exploit the location in which they germinate. [source] Yield Responses of Barley to Leaf Stripe (Pyrenophora graminea) under Experimental Conditions in Southern SyriaJOURNAL OF PHYTOPATHOLOGY, Issue 8-9 2004M. I. E. Arabi Abstract The seed-borne pathogen, Pyrenophora graminea is the causal agent of barley leaf stripe disease. Field trials were undertaken to investigate the impact of leaf stripe on barley yield in two growing seasons in Southern Syria, by comparing plots with and without artificial inoculation. Ten barley cultivars originating from widely dispersed areas were used. The overall response to leaf stripe differed with the differences in susceptibility levels of the cultivars. Grain yield, the number of tillers, kernel weight and plant biomass decreased as disease severity increased. Diseased plants had fewer tillers, and as a consequence a reduced grain yield per plant. High yield losses resulted from leaf stripe in susceptible cultivars in Arrivate, Furat 1, WI2291 and Arabi Abiad with 44%, 50%, 73% and 92%, respectively. The cultivar Banteng had the best level of resistance to the disease, and is a candidate donor for resistance in future breeding programmes. As leaf stripe can dramatically reduce barley yields under favourable conditions, the disease should be considered by crop improvement programmes in Mediterranean and similar environments. [source] Multi-component stable isotope records from Late Weichselian and early Holocene lake sediments at Imio,ki, Poland: palaeoclimatic and methodological implications,JOURNAL OF QUATERNARY SCIENCE, Issue 8 2009Karina Apolinarska Abstract Late Weichselian and early Holocene climatic and environmental changes are inferred from stable carbon and oxygen isotope records obtained on bulk and biogenic carbonates from the sediment sequence of Lake Lednica, western Poland. Along with sediment and pollen stratigraphic data, a wide range of carbonate components occurring in the sediments was analysed for ,13C and ,18O, including shells of several gastropod species and the bivalve genus Pisidium, carapaces of the ostracod subfamily Candoninae and oogonia of the aquatic macrophyte genus Chara. The development of catchment soils and the onset of authigenic carbonate production in response to the climatic amelioration during the Late Weichselian are clearly reflected by rising carbonate content, distinct isotopic shifts in bulk carbonates and decreasing ,13C values of bulk organic matter in the sediments. The GI-1/GS-1 (the Břlling,Allerřd Interstadial complex/Younger Dryas Stadial) and the GS-1/Preboreal transitions are marked by significant shifts in ,18O values of 2,3,, as well as by distinct changes in carbonate content, indicative of a decrease and a subsequent increase in mean annual temperature. Corresponding ,13C records reflect primarily changes in aquatic productivity, with favourable conditions for phytoplankton and macrophytes during GI-1 and the Preboreal resulting in persistent 13C enrichment. The Younger Dryas Stadial is characterised by depletions in 13C and 18O, with indications of a climatic tripartition. Consistent offsets in ,13C and ,18O between records obtained on specific carbonate components reflect vital effects in combination with seasonal characteristics and habitat preferences of the respective carbonate-precipitating biota. Largely parallel first-order variations in ,13C and ,18O of the different carbonate components demonstrate that individual isotope records may provide important palaeoclimatic information, although more detailed reconstructions can be obtained from multi-component analysis. Copyright © 2009 John Wiley & Sons, Ltd. [source] Temporal distribution and composition of the ichthyoplankton from Leopoldo's Inlet on the Upper Paraná River floodplain (Brazil)JOURNAL OF ZOOLOGY, Issue 4 2002Reinaldo José de Castro Abstract Temporal distribution and composition of ichthyoplankton and their relationships with some environmental variables of Leopoldo's Inlet (Ressaco do Leopoldo) on the upper Paraná River floodplain, southern Brazil, were analysed. Samples were taken from February 1991 to February 1992, and 3480 larvae were collected. The highest density of larvae was observed in November 1991 (36.79 larvae/10 m3) at night (night/day ratio 7: 1). Species composition showed a predominance of Characiformes (80%). There was a high density (4.28 larvae/10 m3) of Bryconamericus stramineus throughout almost the whole study period. The majority of the species were more frequently collected at night. Pearson's correlation indicated a relationship between larval density, temperature, and pluviometric index. Leopoldo's Inlet, whose ichthyofauna is mainly composed of grazing and resident species, shows favourable conditions for fish reproduction and development. [source] Lifetime reproductive output of Calliphora vicina and Lucilia sericata in outdoor caged and field populations; flight vs. egg production?MEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2006LEWIS DAVIES Abstract Females of the blowflies Calliphora vicina (Robineau-Desvoidy) and Lucilia sericata (Meigen) (Diptera: Calliphoridae) maintained in sheltered outdoor cages and supplied with excess food, oviposited later than would have been expected from the temperature-sum. The survival rates of the caged flies was high and the isolation of flies from predation, extreme temperatures and food shortages is likely to have contributed to this. Despite good survival rates, subsequent egg production over the greater part of the adult life span was reduced to ,24% for C. vicina and ,55% for L. sericata, of the potential expected from the published temperature-sums required for the maturation of successive egg batches. The data suggest that under field-cage conditions there is a considerable variation in egg development between individuals of the same age and that this variation should not be overlooked, since it may have significant implications in ecological and forensic investigations; however, the cause of this variability remains unclear. While lower than expected, the reproductive outputs recorded in the cages were nevertheless considerably greater than those that have been estimated for blowflies in the field and illustrate the potential for population increase in these species under favourable conditions. The possibility of a greater energy investment in flight activity relative to reproductive output in C. vicina compared to L. sericata is proposed. [source] Interactions between dispersal, competition, and landscape heterogeneityOIKOS, Issue 7 2007Ace North It is widely acknowledged that space has an important role in population regulation, yet more specific knowledge into how the relevant factors interact attains little consensus. We address this issue via a stochastic, individual based model of population dynamics, in a continuous space continuous time framework. We represent habitat quality as a continuously varying surface over the two-dimensional landscape, and assume that the quality affects either fecundity (rate of propagule production) or probability of propagule establishment. We control the properties of the landscape by two parameters, which we call the patch size (the characteristic length scale in quality variation), and the level of heterogeneity (the characteristic quality difference between poor quality and high quality areas). In addition to such exogenous variability, we also account for endogenous factors causing spatial variation by assuming localised dispersal and competition. We find that heterogeneity has a general positive effect on population density, and hence it is beneficial to improve best quality habitat at the expense of worst quality habitat. With regards to patch size, we find an intermediate optimum, due to a conflict between minimising the loss of propagules to low quality regions and maximising the benefits of heterogeneity. We address the consequences of regional stochasticity by allowing the environmental conditions change in time. The cost of having to continuously track where the favourable conditions have moved to ultimately reduces population size. [source] Sex Ratio of Some Long-Lived Dioecious Plants in a Sand Dune AreaPLANT BIOLOGY, Issue 5 2004T. J. de Jong Abstract: In dioecious plants the fraction of males among flowering plants in the field (the secondary sex ratio) is the result of the fraction of males in the seeds (the primary sex ratio) and the subsequent survival and age at first reproduction of the two genders. It has been assumed that survival and age at first reproduction are the main determinants of biased secondary sex ratio but, especially for long-lived perennials, few data are available. We address this issue for natural populations of four long-lived perennials in a dune area. In Asparagus officinale and Bryonia dioica, the secondary sex ratio was unbiased. In Salix repens the secondary sex ratio was female-biased (0.337). Hippophae rhamnoides populations were male-biased; the average sex ratio of flowering plants was 0.658, while the fraction of males varied between 0.39 near the sea to 0.84 at the inland side of the dunes. The primary sex ratio was estimated by germinating seeds and growing plants under favourable conditions with minimal mortality. In S. repens the primary sex ratio in seeds was variable among mother plants and was, on average, female-biased (0.289). This is close to the secondary sex ratio, suggesting that the female bias already originates in the seed stage. In Hippophae rhamnoides the primary sex ratio was slightly male-biased (0.564). We argue that in this species, apart from the primary sex ratio, higher mortality and a later age at first reproduction for females contribute to the strong male bias among flowering plants in the field. [source] Estimating the germination dynamics of Plasmopara viticola oospores using hydro-thermal timePLANT PATHOLOGY, Issue 2 2008V. Rossi The effects of environmental conditions on the variability in germination dynamics of Plasmopara viticola oospores were studied from 1999 to 2003. The germination course was determined indirectly as the relative infection incidence (RII) occurring on grape leaf discs kept in contact with oospores sampled from a vineyard between March and July. The time elapsed between 1 January and the infection occurrence was expressed as physiological time, using four methods: (i) sums of daily temperatures > 8°C; (ii) hourly temperatures > 10°C; (iii) sums of hourly rates from a temperature-dependent function; or (iv) sums of these rates in hours with a rain or vapour pressure deficit , 4·5 hPa (hydro-thermal time, HT). An equation of Gompertz in the form RII = exp[,a · exp(,b · HT)] produced an accurate fit for both separate years (R2 = 0·97 to 0·99) and pooled data (R2 = 0·89), as well as a good accuracy in cross-estimating new data (r between observed and cross-estimated data were between 0·93 and 0·99, P < 0·0001). It also accounted for a great part of the variability in oospore germination between years and both between and within sampling periods. Therefore, the equation of Gompertz (with a = 15·9 ± 2·63 and b = 0·653 ± 0·034) calculated over hydro-thermal time, a physiological time accounting for the effects of both temperature and moisture, produced a consistent modelling of the general relationships between the germination dynamics of a population of P. viticola oospores and weather conditions. It represents the relative density of the seasonal oospores that should have produced sporangia when they have experienced favourable conditions for germination. [source] Infection and colonization of bean leaf by Phaeoisariopsis griseolaPLANT PATHOLOGY, Issue 1 2001E. O. Monda Infection and spread of Phaeoisariopsis griseola in the leaf of bean (Phaseolus vulgaris) were investigated by scanning and transmission electron microscopy. Conidia of P. griseola germinated by releasing a germ tube either at one end of the conidia or both ends. The germ-tube growth followed the contours of epidermal cells. The fungus entered the leaf through the stomata and grew mainly intercellularly between mesophyll and palisade cells. The chloroplast envelope and plasma membrane of adjacent cells disintegrated, lost structural integrity and dried out. Hyphae did not penetrate host cells. A stroma subsequently formed on the leaf surface. Conidiophores elongated under favourable conditions forming synnemata with conidia at the tips of conidiophores. Conidiophores also emerged through stomata. [source] Voluntary Association in Public Goods Experiments: Reciprocity, Mimicry and Efficiency,THE ECONOMIC JOURNAL, Issue 506 2005Talbot Page We find that a process of voluntary association where individuals express a preference about whom they want to be associated with can create strong incentives to increase efficiency and contributions in provision of a public good. This process of endogenous group formation perfectly sorted contributions by the order of group formation. Comparison of middle and last period behaviour suggests that a majority of the subject population are conditional cooperators, with a minority of monetary payoff maximisers. The experiment illustrates that under favourable conditions, where the opportunities of entry and exit are symmetrically balanced, a process of voluntary association can mitigate the free-rider problem. [source] Drug-induced readthrough of premature stop codons leads to the stabilization of laminin ,2 chain mRNA in CMD myotubesTHE JOURNAL OF GENE MEDICINE, Issue 2 2008Valérie Allamand Abstract Background The most common form of congenital muscular dystrophy is caused by a deficiency in the ,2 chain of laminin-211, a protein of the extracellular matrix. A wide variety of mutations, including 20 to 30% of nonsense mutations, have been identified in the corresponding gene, LAMA2. A promising approach for the treatment of genetic disorders due to premature termination codons (PTCs) is the use of drugs to force stop codon readthrough. Methods Here, we analyzed the effects of two compounds on a PTC in the LAMA2 gene that targets the mRNA to nonsense-mediated RNA decay, in vitro using a dual reporter assay, as well as ex vivo in patient-derived myotubes. Results We first showed that both gentamicin and negamycin promote significant readthrough of this PTC. We then demonstrated that the mutant mRNAs were strongly stabilized in patient-derived myotubes after administration of negamycin, but not gentamicin. Nevertheless, neither treatment allowed re-expression of the laminin ,2-chain protein, pointing to problems that may have arisen at the translational or post-translational levels. Conclusions Taken together, our results emphasize that achievement of a clinical benefit upon treatment with novel readthrough-inducing agents would require several favourable conditions including PTC nucleotide context, intrinsic and induced stability of mRNA and correct synthesis of a full-length active protein. Copyright © 2007 John Wiley & Sons, Ltd. [source] Sea-land breeze development during a summer bora event along the north-eastern Adriatic coastTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 651 2010Maja Teli, man Prtenjak Abstract The interaction of a summer frontal bora and the sea-land breeze along the north-eastern Adriatic coast was investigated by means of numerical simulations and available observations. Available measurements (in situ, radiosonde, satellite images) provided model validation. The modelled wind field revealed several regions where the summer bora (weaker than 6 m s,1) allowed sea-breeze development: in the western parts of the Istrian peninsula and Rijeka Bay and along the north-western coast of the island of Rab. Along the western Istrian coast, the position of the narrow convergence zone that formed depended greatly on the balance between the bora jets northward and southward of Istria. In the case of a strong northern (Trieste) bora jet, the westerly Istrian onshore flow presented the superposition of the dominant swirled bora flow and local weak thermal flow. It collided then with the easterly bora flow within the zone. With weakening of the Trieste bora jet, the convergence zone was a result of the pure westerly sea breeze and the easterly bora wind. In general, during a bora event, sea breezes were somewhat later and shorter, with limited horizontal extent. The spatial position of the convergence zone caused by the bora and sea-breeze collision was strongly curved. The orientation of the head (of the thermally-induced flow) was more in the vertical causing larger horizontal pressure gradients and stronger daytime maximum wind speed than in undisturbed conditions. Except for the island of Rab, other lee-side islands in the area investigated did not provide favourable conditions for the sea-breeze formation. Within a bora wake near the island of Krk, onshore flow occurred as well, although not as a sea-breeze flow, but as the bottom branch of the lee rotor that was associated with the hydraulic jump-like feature in the lee of the Velika Kapela Mountain. Copyright © 2010 Royal Meteorological Society [source] Role of nocturnal turbulence and advection in the formation of shallow cumulus over landTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 628 2007Jordi Vilŕ-Guerau de Arellano Abstract Shallow cumuli over land are normally studied from a diurnal perspective. However, the thermodynamic vertical profiles of the morning transition may play an important role in setting up favourable conditions for the formation of shallow cumuli. In turn, these profiles are highly dependent on the evolution of the nocturnal boundary characteristics and of their layer aloft. By analysing thermodynamic profiles measured by radiosondes launched every three hours at four different stations, we are able to determine how horizontal advection and turbulent mixing modify the atmospheric stability and the differences in potential temperature and specific humidity at the interface between the atmospheric boundary layer and the layer above it. Two consecutive nights are studied. They show very similar boundary-layer development; but variations in the layer aloft by a low-level-jet advection event during the second night, and intense turbulent mechanical mixing, lead to the development of two diurnal boundary layers with very different characteristics: the first one clear, the second cloudy. To complete the observational study, we perform a sensitivity analysis using a mixed-layer model to examine the role of the morning initial conditions in the formation of shallow cumuli over land. The complexity and subtlety of the observed situation,namely, the interaction of a strongly-mixed nocturnal boundary layer and horizontal advection,make this case suitable for testing the capacity of mesoscale models to reproduce cloudy boundary layers that are largely dependent on conditions during the previous night. Copyright © 2007 Royal Meteorological Society [source] Quantitative trait loci underlying milk production traits in sheepANIMAL GENETICS, Issue 4 2009B. Gutiérrez-Gil Summary Improvement of milk production traits in dairy sheep is required to increase the competitiveness of the industry and to maintain the production of high quality cheese in regions of Mediterranean countries with less favourable conditions. Additional improvement over classical selection could be reached if genes with significant effects on the relevant traits were specifically targeted by selection. However, so far, few studies have been undertaken to detect quantitative trait loci (QTL) in dairy sheep. In this study, we present a complete genome scan performed in a commercial population of Spanish Churra sheep to identify chromosomal regions associated with phenotypic variation observed in milk production traits. Eleven half-sib families, including a total of 1213 ewes, were analysed following a daughter design. Genome-wise multi-marker regression analysis revealed a genome-wise significant QTL for milk protein percentage on chromosome 3. Eight other regions, localized on chromosomes 1, 2, 20, 23 and 25, showed suggestive significant linkage associations with some of the analysed traits. To our knowledge, this study represents the first complete genome scan for milk production traits reported in dairy sheep. The experiment described here shows that analysis of commercial dairy sheep populations has the potential to increase our understanding of the genetic determinants of complex production-related traits. [source] Effects of pioneer shrubs on the recruitment of the fleshy-fruited tree Olea europaea ssp. cuspidata in Afromontane savannaAPPLIED VEGETATION SCIENCE, Issue 1 2006Raf Aerts Abstract Question: Is seedling recruitment of a fleshy-fruited tree in degraded Afromontane savanna dependent on shelter from pioneer shrubs, and is shelter availability related to shrub traits? Location: Degraded montane savanna in northern Ethiopia (13°36,N, 39°21,E). Method: Nurse plants of Olea europaea ssp. cuspidata seedlings were recorded using T-square plotless sampling and clustered according to shrub traits, using Ward's method after Principal Components Analysis. Facilitation was further examined through experimental planting and Kaplan-Meier survival analysis. Results: Both in grazed and protected areas, Olea recruits were found exclusively under shrubs, primarily under Euclea racemosa although Acacia etbaica was more abundant. Olea recruitment is distributed randomly at landscape scale, but depends on shelter at patch scale. Shelter ability is related to shrub shape and species identity. Dense multi-stemmed shrubs with a wide base and crown on a mulch-rich mound are key recruitment foci. Euclea shrubs have these favoured traits and probably act as preferential perching sites for avian seed dispersers. Soil and organic matter accumulation under Euclea shrubs may also create favourable conditions for Olea germination and survival. Experimentally planted seedlings had a better chance for survival under Euclea. Conclusions:Olea regeneration is probably subject to both passive (disperser-mediated) and active facilitation. Small changes of shrub traits can alter the suitability of a patch for Olea recruitment. Protection of shrubs can increase facilitation for seedlings, while pruning may reduce competition for saplings and thus enhance forest succession. Planting of raised Olea seedlings under Euclea shrubs in years with a good rainy season may further assist forest restoration. [source] The impact of site conditions and seed dispersal on restoration success in alluvial meadowsAPPLIED VEGETATION SCIENCE, Issue 1 2003Tobias W. Donath Wisskirchen & Haeupler (1998) Abstract. We studied the restoration success of flood plain meadows in the northern Upper Rhine valley, where between 1988 and 1992, 35 ha of arable land was converted into grassland and subsequently managed for nature conservation. Remnant populations of typical alluvial meadow species were found in old meadows and along drainage ditches that dissect the whole area. We analysed the site conditions and phytosociological relevés in old and new meadows. Small differences in site parameters between old and new meadows contrasted with a clear floristic differentiation between the two meadow types. The vegetation of old meadows was much more differentiated along prevailing environmental gradients than the vegetation of new meadows. Despite the favourable site conditions for the re-establishment of species-rich meadows on the former arable land, restoration success was limited to the vicinity of remnant stands. In contrast to old meadows, indicator species of new grassland were still typical species of regularly disturbed ruderal and arable habitats, often capable of building up a persistent seed bank. The precise mapping of 23 target species revealed that even wind dispersal predominantly leads to re-establishment in the close circumference of parent plants. We found no indication that regular flooding, hay-making and autumnal grazing had an impact on recolonization of newly created grassland. Even under favourable conditions for the re-establishment of target species, restoration success in alluvial meadows proved to be strongly dispersal limited. We discuss the implications of our findings for future restoration management in grasslands. [source] Supplementary oxygen and temperature management during live transportation of greenlip abalone, Haliotis laevigata (Donovan, 1808)AQUACULTURE RESEARCH, Issue 7 2009Erin J Bubner Abstract Live greenlip abalone, Haliotis laevigata, are highly valued in Australian export markets with demand increasingly being met with cultured stock. Live transportation of abalone requires the maintenance of favourable conditions within transport containers for periods exceeding 35 h. We examined the combined effects of temperature regulation (ice provision) and of supplemental oxygen (60% and 100% concentrations) on mortality rates of abalone over 7 days following a 35-h simulated live-transport experiment. We also examined the physiological condition of greenlip abalone (oxygen consumption rate, haemolymph pH and weight) during the simulation experiment. The provision of ice and supplementary oxygen reduced abalone mortalities. Omission of ice and supplementary oxygen during the transport simulation resulted in mortality rates ranging from 70% to 100%. The addition of ice to containers with ambient oxygen concentrations decreased average mortality rates by 50%. While supplementary oxygen further reduced these rates, the provision of both ice and 100% oxygen was by far the most effective combination, reducing mortalities to between 2% and 6%. Supplementary oxygen increased oxygen consumption rates of abalone above those transported at ambient oxygen concentrations. Live-transport decreased haemolymph pH in all treatments but was most pronounced in treatments without ice or supplementary oxygen. On average, abalone lost 7,13% of their weight during the simulation but this loss was independent of transport treatment. [source] Cell growth and cholesterol metabolism in human glucose- 6-phosphate dehydrogenase deficient lymphomononuclear cellsCELL PROLIFERATION, Issue 3 2002Batetta B. Atherosclerosis is an inflammatory-fibroproliferative response of the arterial wall involving a complex set of interconnected events where cell proliferation (lymphomonocytes, and endothelial and smooth-muscle cells) and substantial perturbations of intracellular cholesterol metabolism are considered to be among the main features. Glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the hexose-monophosphate shunt pathway, is an essential enzyme involved in both cell growth and cholesterol metabolism, raising the question as to whether G6PD deficiency may have metabolic and growth implications in a deficient population. In the present study, we investigated cell growth and cholesterol metabolism in peripheral blood lymphomononuclear cells (PBMC) from G6PD-normal (n = 5) and -deficient (n = 5) subjects stimulated with lectins (phytohaemoagglutinin and Concanavalin A). G6PD activity, DNA ([3H]-thymidine incorporation) cholesterol synthesis and esterification ([14C]-acetate and [14C]-oleate incorporation), and G6PD, HMGCoA reductase and low density lipoprotein (LDL) receptor mRNA levels (RT-PCR) all increased following lectin stimulation in both normal and G6PD-deficient cells. However, these parameters were significantly lower in G6PD-deficient cells (P < 0.05). It is of interest that G6PD-deficient PBMC, which showed lower expression of G6PD and higher expression of the LDL receptor gene than normal PBMC under basal conditions, exhibited an opposite pattern after stimulation: G6PD and HMGCoA reductase being expressed at significantly higher levels in deficient than in normal cells (P < 0.05). We conclude that the reduced capability of G6PD-deficient cells to respond to mitogenic stimuli and to synthesize cholesterol esters may represent favourable conditions for reducing the risk of cardiovascular diseases. [source] | |||||||||||||||||||||||||||||||