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128 results for “age determination”
Fig. 1 in Age Determination And Some Growth Parameters Of A Rana Ridibunda Population In Turkey
Fig. 1. Age distribution of the population
Fig. 4 in Age Determination And Some Growth Parameters Of A Rana Ridibunda Population In Turkey
Fig. 4. The mean growth rates of males and females
Data for: Elevated inbreeding in Heliconia tortuosa is determined by tropical forest stand age, isolation, and loss of hummingbird functional diversity
<p>Forest conversion and habitat loss are major threats to biological diversity. Forest regeneration can mitigate the negative effects of old growth forest loss on species diversity, but less is known about the extent to which forest loss reduces genetic diversity in remnant populations and whether secondary forests play a role in the maintenance of genetic diversity. We quantified genetic diversity in a tropical hummingbird-pollinated understory herb, <em>Heliconia tortuosa</em>, across a landscape mosaic of primary and secondary forest regrowth. Using microsatellite genotypes from >850 adult and juvenile plants within 33 forest patches and extensive bird surveys, we examined the effect of contemporary and historical landscape features including forest age (primary vs. secondary forest), stand isolation, and pollinator assemblages on genetic diversity and levels of inbreeding in <em>H. tortuosa</em>. We found that inbreeding was up to 3x higher in secondary forest, and this effect was amplified with reductions in primary forest in the surrounding landscape through reduced observed heterozygosity in isolated fragments. Inbreeding in forest patches was negatively correlated with the local frequency of specialist long-distance foraging traplining hummingbirds. Traplining hummingbirds therefore appear to facilitate mating among unrelated plants - an inference we tested using empirically parameterized simulations. Higher levels of inbreeding in <em>H. tortuosa</em> are therefore associated with reduced functional diversity of hummingbirds in secondary forests and forest patches isolated from primary forests. Our findings suggest a cryptic consequence of primary forest loss and secondary forest regeneration through the disruption of mutualistic interactions resulting in the erosion of genetic diversity in a common understory plant.</p>
Fig. 3 in Age determination of the Mongolian wild ass (Equus hemionus Pallas, 1775) by the dentition patterns and annual lines in the tooth cementum
Fig. 3. Occurrence of deciduous and permanent first premolars in the Mongolian wild ass skull.
Fig. 1 in Age determination of the Mongolian wild ass (Equus hemionus Pallas, 1775) by the dentition patterns and annual lines in the tooth cementum
Fig. 1. First lower incisor (A) and its longitudinal section (B) with annual lines (C).
Age determination of galactic B-type stars in double-lined eclipsing binaries
<p>We present the results of age determination for galactic B-type main sequence stars which are components of double-lined eclipsing binaries. Only detached systems are considered. We analyze 38 binary systems that meet such criteria. The analysis is based on evolutionary computations and we consider that the age is determined if there is a common value from the radius−age diagrams and the agreement in the position of both components in the Hertzsprung-Russell diagram. In some cases, to meet these two conditions, it was necessary to adjust the value of the metallicity, Z or/and the parameter of overshooting from the convective core, αov. We determine the consistent age for 33 binaries out of 38. Besides, we made an extensive computations and for each system we give the range of αov and Z, for which the consistent solutions exist. The age of the studied B-type main sequence stars ranges, as counted from the Zero Age Main Sequence, from about 2.5 Myr to about 200 Myr.</p>
Landslide age, elevation and residual vegetation determine tropical montane forest canopy recovery and biomass accumulation after landslide disturbances in the Peruvian Andes
<p>Landslides are common natural disturbances in tropical montane forests. While the geomorphic drivers of landslides in the Andes have been studied, factors controlling post-landslide forest recovery across the steep climatic and topographic gradients characteristic of tropical mountains are poorly understood.</p> <p>Here we use a LiDAR-derived canopy height map coupled with a 25-year landslide time series map to examine how landslide, topographic, and biophysical factors, along with residual vegetation, affect canopy height and heterogeneity in regenerating landslides. We also calculate aboveground biomass accumulation rates and estimate the time for landslides to recover to mature forest biomass levels.</p> <p>We find that age and elevation are the biggest determinants of forest recovery, and that the jump-start in regeneration that residual vegetation provides lasts for at least 18 years. Our estimates of time to biomass recovery (31.6-37.1 years) are surprisingly rapid, and as a result we recommend that future research pair LiDAR with hyperspectral imagery to estimate forest aboveground biomass in frequently disturbed landscapes.</p> <p>Synthesis: Using a high-resolution LiDAR dataset and a time-series inventory of 608 landslides distributed across a wide elevational gradient in Andean montane forest, we show that age and elevation are the most influential predictors of forest canopy height and canopy variability. Other features of landslides, in particular the presence of residual vegetation, shape post-landslide regeneration trajectories. LiDAR allows for a detailed analysis of forest structural recovery across large landscapes and numbers of disturbances, and provides a reasonable upper bound on aboveground biomass accumulation rates. However, because this method does not capture the effect of compositional change through succession on aboveground biomass, wherein high-wood density species gradually replace light-wooded pioneer species, it overestimates aboveground biomass. Given previously estimated stem turnover rates along this elevational gradient, we posit that aboveground biomass recovery takes at least three times as long as our recovery time estimates based on LiDAR-derived structure alone.</p>
Fire severity as a key determinant of aboveground and belowground biological community recovery in managed even-aged boreal forests
<p><span>Changes in fire regime of boreal forests in response to climate warming are expected to impact post-fire recovery. However, quantitative data on how managed forests sustain and recover from recent fire disturbance are limited. </span></p> <p><span>Two years after a large wildfire in managed even-aged boreal forests in Sweden,</span><span> we investigated how recovery of aboveground and belowground communities, i.e., understory vegetation and soil microbial and faunal communities, responded to variation in the severity of soil (i.e., consumption of soil organic matter) and canopy fires (i.e., tree mortality). </span></p> <p><span>While fire overall enhanced diversity of understory vegetation through colonization of fire adapted plant species, it reduced the abundance and diversity of soil biota. We observed contrasting effects of tree- and soil-related fire severity on survival and recovery of understory vegetation and soil biological communities. </span><span>Severe fires that killed overstory <em>Pinus sylvestris</em> promoted a successional stage dominated by the mosses <em>Ceratodon purpureus</em> and <em>Polytrichum juniperum</em>, but reduced regeneration of tree seedlings and disfavoured the ericaceous dwarf-shrub<em> Vaccinium vitis-idaea</em> and the grass<em> Deschampsia flexuos</em>a. Moreover, high tree mortality from fire reduced fungal biomass and changed fungal community composition, in particular that of ectomycorrhizal fungi, and reduced the fungivorous soil Oribatida. In contrast, soil-related fire severity had little impact on vegetation composition, fungal communities and soil animals. Bacterial communities responded to both tree- and soil-related fire severity. </span></p> <p><span>Synthesis: Our results two years post-fire suggest that a change in fire regime from a historically low-severity ground-fire regime, with fires that mainly burns into the soil organic layer, to a </span><span>stand-replacing </span><span>fire regime with a high degree of tree mortality, as may be expected with climate change, is likely to impact the short-term recovery of stand structure and above- and belowground species composition of even-aged <em>P. sylvestris</em> </span><span>boreal forests.</span></p>
A Study to Determine the Safety and Tolerability of Dupilumab (REGN668/SAR231893) in Patients Aged ≥6 to <18 Years With Atopic Dermatitis (Eczema)
ClinicalTrials.gov study NCT02407756. IPD Sharing: Not stated. Countries: 6. Publications: 2.
Determining Age Appropriateness of Children's Products and Toys
ClinicalTrials.gov study NCT02544035. IPD Sharing: Not stated. Countries: 1. Publications: 3.
Study to Determine the Immunogenicity and Safety of GlaxoSmithKline (GSK) Biologicals; Infanrix Hexa at 2, 4 and 6 Months of Age in Healthy Infants
ClinicalTrials.gov study NCT02096263. IPD Sharing: YES. Countries: 1. Publications: 1.
Determinants of Age Related Breathing Instability During Non-Rapid-Eye-Movement (NREM) Sleep
ClinicalTrials.gov study NCT00732199. IPD Sharing: NO. Countries: 1. Publications: 1.
Fire severity as a key determinant of aboveground and belowground biological community recovery in managed even-aged boreal forests
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Data from: Changes in age-structure over four decades were a key determinant of population growth rate in a long-lived mammal
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Data from: Seasonality determines patterns of growth and age structure over a geographic gradient in an ectothermic vertebrate
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Data for: Elevated inbreeding in Heliconia tortuosa is determined by tropical forest stand age, isolation, and loss of hummingbird functional diversity
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Landslide age, elevation and residual vegetation determine tropical montane forest canopy recovery and biomass accumulation after landslide disturbances in the Peruvian Andes
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Data from: Determinants of age at first reproduction and lifetime breeding success revealed by full paternity assignment in a male ungulate
Age at first reproduction is an important determinant of individual variation in reproductive success in ungulates, but few studies have examined its relationship with later fitness-related traits in males. We used a long-term individual based study of a harvested moose population to quantify the individual reproductive performance and survival of males, as well as to examine the determinants of age at first reproduction and consequences of age at first reproduction on lifetime breeding success. The probability that a male successfully reproduced at the age of two was negatively related to the mean age of adult males in the population, but the relationship weakened with increasing population size. Large antlers and large body mass relative to other males in the population increased the number of calves sired at their first successful mating season. In addition, those that successfully reproduced as two year-olds were more likely to sire calves the next year, making them more productive at a given age compared to those that first reproduced at the age of three or older. We emphasize the importance for males to start reproducing as soon as possible in a harvested population to gain lifetime fitness benefits, as surviving the hunt is a major determinant of reproductive success in this population. We found no costs of early reproduction in males, hence leading to high individual heterogeneity in male reproductive performance. The apparent lack of reproductive costs could partly be explained by the age distribution in the population, individual variation in early-life body mass and antler size, and differences in probabilities of being killed during hunt between successful and unsuccessful males.
Data from: Blood-stage parasitaemia and age determine Plasmodium falciparum and P. vivax gametocytaemia in Papua New Guinea
A better understanding of human-to-mosquito transmission is crucial to control malaria. In order to assess factors associated with gametocyte carriage, 2083 samples were collected in a cross-sectional survey in Papua New Guinea. Plasmodium species were detected by light microscopy and qPCR and gametocytes by detection of pfs25 and pvs25 mRNA transcripts by reverse-transcriptase PCR (qRT-PCR). The parasite prevalence by PCR was 18.5% for Plasmodium falciparum and 13.0% for P. vivax. 52.5% of all infections were submicroscopic. Gametocytes were detected in 60% of P. falciparum-positive and 51% of P. vivax-positive samples. Each 10-fold increase in parasite density led to a 1.8-fold and 3.3-fold increase in the odds of carrying P. falciparum and P. vivax gametocytes. Thus the proportion of gametocyte positive and gametocyte densities was highest in young children carrying high asexual parasite densities and in symptomatic individuals. Dilution series of gametocytes allowed absolute quantification of gametocyte densities by qRT-PCR and showed that pvs25 expression is 10-20 fold lower than pfs25 expression. Between 2006 and 2010 parasite prevalence in the study site has decreased by half. 90% of the remaining infections were asymptomatic and likely constitute an important reservoir of transmission. However, mean gametocyte densities were low (approx. 1-2 gametocyte/μL) and it remains to be determined to what extent low-density gametocyte positive individuals are infective to mosquitos.
Data from: Premating isolation is determined by larval rearing substrates in cactophilic Drosophila mojavensis. X. Age-specific dynamics of adult epicuticular hyrdocarbon expression in response to different host plants
Analysis of sexual selection and sexual isolation in Drosophila mojavensis and its relatives has revealed a pervasive role of rearing substrates on adult courtship behavior when flies were reared on fermenting cactus in preadult stages. Here, we assessed expression of contact pheromones comprised of epicuticular hydrocarbons (CHCs) from eclosion to 28 days of age in adults from two populations reared on fermenting tissues of two host cacti over the entire life cycle. Flies were never exposed to laboratory food and showed significant reductions in average CHC amounts consistent with CHCs of wild-caught flies. Overall, total hydrocarbon amounts increased from eclosion to 14–18 days, well past age at sexual maturity, and then declined in older flies. Most flies did not survive past 4 weeks. Baja California and mainland populations showed significantly different age-specific CHC profiles where Baja adults showed far less age-specific changes in CHC expression. Adults from populations reared on the host cactus typically used in nature expressed more CHCs than on the alternate host. MANCOVA with age as the covariate for the first six CHC principal components showed extensive differences in CHC composition due to age, population, cactus, sex, and age × population, age × sex, and age × cactus interactions. Thus, understanding variation in CHC composition as adult D. mojavensis age requires information about population and host plant differences, with potential influences on patterns of mate choice, sexual selection, and sexual isolation, and ultimately how these pheromones are expressed in natural populations. Studies of drosophilid aging in the wild are badly needed.
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Allen Brain Atlas
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Annotated Behaviour and Observability Dataset (ABODe)
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