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North-west Atlantic rocky intertidal shores contain few species that are affected by sharp environmental gradients. As a result, these communities have been widely used as a model experimental system. Earlier studies focussed on how average differences in ecological processes can be driven by environmental differences. More recently, there is an emphasis on how variability in recruitment and ecological interactions can shape communities. In this chapter, we explore how these two distinctly different conceptual approaches – average effects versus variability in effects – have affected the course of ecological research. Our review touches on how phylogeographic history, large-scale variability in ecological processes and small-scale indirect interactions have contributed to the generation and maintenance of community patterns. We argue that human activities, including harvesting, introducing non-native species, eutrophication and climate change, are likely to increase the variability of ecological processes. We conclude that variability of ecological processes and human activities vary on a scale much larger or longer than a typical experiment. Future studies should explicitly incorporate scales that capture the role of variability on the resilience of coastal ecosystems.
Evaluation of Cr, Mn, Fe, Zn and Se in humans is challenged by the potentially high within-individual variability of these elements in biological specimens, which are poorly characterised. This study aimed to evaluate their within-day, between-day and between-month variability in spot samples, first-morning voids and 24-h collections. A total of 529 spot urine samples (including eighty-eight first-morning voids and 24-h collections) were collected from eleven Chinese adult men on days 0, 1, 2, 3, 4, 30, 60 and 90 and analysed for these five elements using inductively coupled plasma-MS. Intraclass correlation coefficients (ICC) were utilised to characterise the reproducibility, and their sensitivity and specificity were analysed to assess how well a single measurement classified individuals’ 3-month average exposures. Serial measurements of Zn in spot samples exhibited fair to good reproducibility (creatinine-adjusted ICC = 0·47) over five consecutive days, which became poor when the samples were gathered months apart (creatinine-adjusted ICC = 0·33). The reproducibility of Cr, Mn, Fe and Se in spot samples was poor over periods ranging from days to months (creatinine-adjusted ICC = 0·01–0·12). Two spot samples were sufficient for classifying 60 % of the men who truly had the highest (top 33 %) 3-month average Zn concentrations; for Cr, Mn, Fe and Se, however, at least three specimens were required to achieve similar sensitivities. In conclusion, urinary Cr, Mn, Fe, Zn and Se concentrations showed a strong within-individual variability, and a single measurement is not enough to efficiently characterise individuals’ long-term exposures.
This study examines language mixing in 26 Spanish–English dual language
learners over the course of their first year of preschool. The children's
patterns of language choice while interacting in monolingual language contexts
were analyzed at age 3;6 and 4;5 to examine: (1) whether the frequency of
language mixing changed during the year; (2) whether mixing was related to
proficiency as measured by utterance length and lexical diversity; and (3)
whether there were different subgroups of children, among the participants, with
similar proficiency and language use patterns. The results indicate that
language mixing, which was low at both ages, was related to limited lexical
resources only at 3;6. However, by age 4;5, language choice was more constrained
by sociolinguistic variables – children's awareness of the
language prescribed by the majority culture – than by proficiency. An
exploratory cluster analysis further reveals different profiles of learners
sharing similar proficiency and language mixing characteristics.
Prostate positional variability has been widely explored with seminal vesicle (SV) variability, coming into the forefront only in recent years. While planning target volume (PTV) margins and preparation protocols ameliorate the effects of bladder and rectum volume changes on prostate, studies on SV variation have looked at only position, not volume variability.
The aim of this study was to investigate whether the inter-fraction volume variability of the VSs can exist in patients receiving radiotherapy to the prostate.
SV variability was investigated by comparing four on-treatment cone beam computer tomography scans to a planning computer tomography (CT) image for two patients receiving prostate radiotherapy. For each case, variation in volumes (cm3) was compared with intra-observer variation.
SV volume variability was seen in both patients, with the largest change in volume being 78·38%. This variance was considerably (between 2 and 10 times) larger than the measured intra-observer variance.
This study identified the potential for daily SV volume variability in patients receiving prostate radiotherapy. Future large-scale studies are warranted to identify the extent of this motion and potential clinical impact. Evidence-informed PTV margins and possible SV volume control protocols may need to be adopted.
Studies have shown that the reduction in serum TAG concentrations with long-chain n-3 fatty acid supplementation is highly variable among individuals. The objectives of the present study were to compare the proportions of individuals whose TAG concentrations lowered after high-dose DHA and EPA, and to identify the predictors of response to both modalities. In a double-blind, controlled, crossover study, 154 men and women were randomised to three supplemented phases of 10 weeks each: (1) 2·7 g/d of DHA, (2) 2·7 g/d of EPA and (3) 3 g/d of maize oil, separated by 9-week washouts. As secondary analyses, the mean intra-individual variation in TAG was calculated using the standard deviation from the mean of four off-treatment samples. The response remained within the intra-individual variation (±0·25 mmol/l) in 47 and 57 % of participants after DHA and EPA, respectively. Although there was a greater proportion of participants with a reduction >0·25 mmol/l after DHA than after EPA (45 υ. 32 %; P < 0·001), the mean TAG reduction was comparable between groups (–0·59 (sem 0·04) υ. –0·57 (sem 0·05) mmol/l). Participants with a reduction >0·25 mmol/l after both DHA and EPA had higher non-HDL-cholesterol, TAG and insulin concentrations compared with other responders at baseline (all P < 0·05). In conclusion, supplementation with 2·7 g/d DHA or EPA had no meaningful effect on TAG concentrations in a large proportion of individuals with normal mean TAG concentrations at baseline. Although DHA lowered TAG in a greater proportion of individuals compared with EPA, the magnitude of TAG lowering among them was similar.
Specimen-level phylogenetic approaches are widely used in molecular biology for taxonomic and systematic purposes. However, they have been largely ignored in analyses based on morphological traits, where phylogeneticists mostly resort to species-level analyses. Recently, a number of specimen-level studies have been published in vertebrate palaeontology. These studies indicate that specimen-level phylogeny may be a very useful tool for systematic reassessments at low taxonomic levels. Herein, we review the challenges when working with individual organisms as operational taxonomic units in a palaeontological context, and propose guidelines of how best to perform a specimen-level phylogenetic analysis using the maximum parsimony criterion. Given that no single methodology appears to be perfectly suited to resolve relationships among individuals, and that different taxa probably require different approaches to assess their systematics, we advocate the use of a number of methodologies. In particular, we recommend the inclusion of as many specimens and characters as feasible, and the analysis of relationships using an extended implied weighting approach with different downweighting functions. Resulting polytomies should be explored using a posteriori pruning of unstable specimens, and conflicting tree topologies between different iterations of the analysis should be evaluated by a combination of support values such as jackknifing and symmetric resampling. Species delimitation should be consistent among the ingroup and based on a reproducible approach. Although time-consuming and methodologically challenging, specimen-level phylogenetic analysis is a highly useful tool to assess intraspecific variability and provide the basis for a more informed and accurate creation of species-level operational taxonomic units in large-scale systematic studies. It also has the potential to inform us about past speciation processes, morphological trait evolution, and their potential intrinsic and extrinsic drivers in pre-eminent detail.
Protein energy malnutrition (PEM) is prevalent in south-east Asian countries including India. Breeding and introduction of grain protein-rich varieties of legumes such as dolichos bean is considered as cost-effective approach to combat PEM. Exploitation of genetic variability within germplasm accessions (GAs) and/or breeding populations is the short-term strategy for identification and delivery of protein-rich dolichos bean cultivars to cater to the immediate needs of the farmers and target population. A set of 118 dolichos bean genotypes consisting of 96 GAs and 20 advanced breeding lines (ABLs) and two released varieties (RVs) was field evaluated in augmented deign for dry grain yield per plant and their grain protein contents were estimated. The grain protein content among the genotypes ranged from 18.82 to 24.5% with a mean of 21.73%. The magnitude of estimates of absolute range, standardized range, and phenotypic coefficient of variation (PCV) for grain protein content was higher among GAs than those among ABLs + RVs. However, average grain protein contents of GAs were comparable to those of ABLs + RVs. Nearly 50% of the genotypes (mostly GAs) had significantly higher grain protein content than those of RVs, HA 3 and HA 4. The grain protein contents of the genotypes were poorly correlated with grain yield per plant. These results are discussed in relation to strategies to breed grain protein-rich dolichos bean cultivars.
The upward evolution of temperatures in the Antarctic Peninsula has weakened and even reversed in the last two decades. Due to the long-term variability in the region it is not easy to assess whether recent cooling trends are consistent with the internal variability or not. For this reason, this paper assesses the robustness of the trends by analysing their sensitivity with respect to the period selected. Every possible temperature trend in the interval 1958–2016 has been calculated and displayed in a two-dimensional parameter diagram. The results suggest that the warming observed in the Antarctic Peninsula since 1958 is quite robust, as all periods longer than 30 years exhibit statistically significant changes, especially in summer (with lower magnitude and higher significance) and autumn and winter (with larger magnitude and lower significance). Periods shorter than 30 years exhibit alternations of warming and cooling periods, and therefore do not represent robust trends even if they are statistically significant. Consequently, the recent 20-year cooling trend cannot be considered at the moment as evidence of a shift in the overall sign of the trend.
This article focuses on the variability in developmental outcomes of foster children and the implications for foster care research and practice. We first provide a brief overview of our previous work, where we have shown by means of meta-analysis and a longitudinal study that foster children greatly vary with respect to their developmental functioning. We then discuss that it is both the heterogeneity of developmental trajectories and the lack of an accurate model for predicting foster children's development that make the screening and monitoring of foster children's development important. We provide suggestions for screening and monitoring, and discuss the Brief Assessment Checklist as an example of a specific instrument available for screening and monitoring of vulnerable children exposed to severe social adversity. We conclude our article with directions to improve foster care and research on foster care, including a discussion of the effectiveness of and foster children's susceptibility to interventions, support for foster parents and the potential of large national and international studies.
We report marine dissolved organic carbon (DOC) ∆14C from seawater collected from the North central Pacific Ocean (NCP) in 2015. These measurements show DOC ∆14C values averaged –235±5‰ (n=3) in the mixed layer (24–81 m) and –544±5‰ (n=5) in the deep water (1500–5139 m). A comparison of these data with two previously published DOC ∆14C profiles from the NCP in 1985 and 1987 reveals that deep DOC ∆14C values have decreased. We discuss several possible mechanisms that could cause such a shift in DOC ∆14C values, including spatial inhomogeneity and temporal variability due to changes in the dissolution and ∆14C value of surface derived particles in the deep sea. We find that forthcoming profiles of DOC ∆14C results from the NCP will determine the primary mechanisms controlling deep DOC ∆14C distributions, and changes over the past three decades.
European pig production continues to encounter economic and environmental challenges. To address these issues, methods have been developed to assess performances of pig production systems. Recent studies indicate that considering variability in performances among pigs improves the accuracy and reliability of results compared with modelling an average animal. Our objective was to develop a pig fattening unit model able to (i) simulate individual pig performances, including their variability in interaction with farmers’ practices and management, and (ii) assess their effects on technical, economic and environmental performances. Farmer practices included in the model were chosen from a typology generated from on-farm surveys focused on batch management, pig allocation to pens, pig feeding practices, practices of shipping to the slaughterhouse, and management of the remaining pigs. Pigs are represented using an individual-based model adapted from the InraPorc® model. To illustrate the model’s abilities, four scenarios were simulated that combine two feed rationing plans (ad libitum, restricted to 2.5 kg/day) and two feed sequence plans (two-phase, 10-phase). Analysis of variance was performed on the simulated technical, economic and environmental indicators (calculated via Life Cycle Assessment). The feed rationing plan and feed sequence plan significantly affected all indicators except for the premium per pig, for which the feed sequence plan did not have a significant effect. The ‘restricted 10-phase’ scenario maximised gross margin of the fattening unit (14.2 €/pig) and minimised environmental impacts per kg of pig produced. In contrast, the ‘ad libitum two-phase’ scenario generated the lowest margin (8.20 €/pig) and the highest environmental impacts. The model appears to be a promising tool to assess effects of farmers’ practices, pig characteristics and farm infrastructure on technical, economic and environmental performances of the fattening unit, and to investigate the potential of improvement. However, further work is needed, based on virtual experiments, in order to evaluate the effects of a larger diversity of practices.
Single-case experimental designs meeting evidence standards are useful for identifying empirically-supported practices. Part of the research process entails data analysis, which can be performed both visually and numerically. In the current text, we discuss several statistical techniques focusing on the descriptive quantifications that they provide on aspects such as overlap, difference in level and in slope. In both cases, the numerical results are interpreted in light of the characteristics of the data as identified via visual inspection. Two previously published data sets from patients with traumatic brain injury are re-analysed, illustrating several analytical options and the data patterns for which each of these analytical techniques is especially useful, considering their assumptions and limitations. In order to make the current review maximally informative for applied researchers, we point to free user-friendly web applications of the analytical techniques. Moreover, we offer up-to-date references to the potentially useful analytical techniques not illustrated in the article. Finally, we point to some analytical challenges and offer tentative recommendations about how to deal with them.
In this study, fresh and frozen–thawed semen of Nitra and Zobor rabbit breeds were evaluated for potential inter-breed or inter-male differences in sperm quality traits. Individual male semen from four rabbits of each breed were diluted (v:v; 1:1) in a freezing medium composed of a commercial diluent, 16% of dimethyl sulphoxide (DMSO), 4% of Ficoll 70 and 2% of sucrose and frozen in liquid nitrogen vapours before being plunged into liquid nitrogen. Different motility traits, viability and plasma membrane integrity of fresh and frozen–thawed semen were evaluated in vitro using computer-assisted sperm analysis and flow cytometry. To evaluate the sperm fertilization ability, artificial insemination of fresh and frozen–thawed sperm was performed. Our results showed the effect of breed (P ≤ 0.05) on frozen–thawed sperm viability and plasma membrane integrity. Moreover, individual variability in semen quality among the rabbits was revealed (0.31 to 0.71 among quality traits). Our results thereby confirmed that the cryopreservation procedure could not ensure comparable sperm post-thaw survival for different breeds or males. Nevertheless, correlations between numbers of fresh total motile and progressively moving sperm and several quality parameters measured post thawing were revealed. Therefore, we suggest that the objective assessment of fresh rabbit sperm motility may be an effective indicator of frozen–thawed semen quality. Consequently, regular semen assessment is required in order to preserve good-quality insemination doses from native breeds.
Trilobites are important elements of the Devonian macrobenthos; some of them were collected in the Chefar el Ahmar Formation, from two sections located near Béni Abbès in the Saoura Valley (Ougarta Basin, Saharan Algeria). This formation is characterized by alternations of claystones and limestones, and it is considered to be late Emsian to early Frasnian in age. Only the lower part of this formation has yielded trilobites so far; their presence has been known for a long time. Phacopines clearly dominate the trilobite assemblages, with Austerops, Barrandeops, Chotecops and Phacops s.l. as the main genera. Two new species are described (Austerops salamandaroides sp. nov. and Phacops ouarouroutensis sp. nov.), while some other taxa are presented in open nomenclature. Comparisons are made with closely allied species. These new trilobite occurrences have been analysed in terms of their intra- and interspecific variability and biodiversity. The occurrence of Struveaspis maroccanica, previously known from the Saoura Valley, provides an early Eifelian age, which is also confirmed by the presence of trilobites Thysanopeltis and Koneprusites, and ostracods Bairdiocypris devonica and Bufina ?subovalis.
Climate change affects the livestock populations. As temperature increases, the rainfall distribution patterns shifts. These indirectly change the ecosystems like changes in crop yield, alter the distribution of animal diseases, geographically restriction of rare breed populations and increased competition for resources. Therefore, the objective of the study was to quantify impacts of climate variability on livestock population dynamics and breed distribution patterns. The study was conducted in Gondar Zuria, Farta and Bahir Dar Zuria districts. The sites were selected based on agro-ecology and livestock distribution potential. Data were collected through desk reviews of different documents and studies, focused group discussions, key informants interviews and different projection models. The results revealed that 70 percent of respondents believed that the trends of livestock breed distribution varied from year to year and from agro-ecology to agro-ecology. The number of cattle and equines are decreasing from year to year due to climate variability. Particularly, the crossbred cattle population decreased in 1998, 2002 and 2008 due to shortage of rainfall, increments of temperature and feed shortage. A correlation analysis was used to quantify impacts of temperature and rainfall on livestock population dynamics and breed distribution. The analyses revealed that sheep (r = −0.535, P < 0.05) and cattle (r = −0. 512, P < 0.05) were negatively affected by climate variability. Whereas goats were having positive relationship (r = 0.345, P < 0.001). As the average maximum temperature steadily increases, the population dynamics of ruminant livestock fluctuated after the year 1996. About 92.2, 78 and 83.3 percent respondents in Farta, Gondar Zuria and Bahir Dar Zuria districts, respectively, stated that there is a fluctuation in amount of rainfall distribution during the main rainy seasons. About 84.5 percent of respondent of the three districts also believed that climate change made variation in rainfall distribution. About 52 percent of the respondents also suggested that if livestock is to be protected from climate change and related effects, changing the farming system with appropriate breed is important and can be achieved with the zero-grazing system. The farmers also recommended with stocking climate change adaptive and productive breeds. In conclusion, climate variability affected livestock population dynamics and breed distribution pattern negatively.
Many compact galactic and extra-galactic sources have a luminosity in the slim accretion disk regime, i.e. L/LE ∼ 1, where LE is the Eddington luminosity. The correspondingly large accretion rates diminish the relevance of variability interpretations based on the thin disk model. This paper explores the possible connection between variability in AGN and local instabilities in slim disks, and points out some relevant areas of future research.
CGRO and IUE observations suggest that the strong, aperiodic variability seen in the Exosat long-look observations of AGN extends over a much wider energy band. Some BL Lac objects (but no Seyfert 1 galaxies) have shown X-ray variations which were so rapid that they violate the assumptions of isotropy inherent in the Eddington limit. In the ultraviolet, Seyfert 1s as a class show an anti-correlation between the variability amplitude and luminosity, while BL Lacs show a positive correlation. Furthermore, Seyfert 1s show strong flux-correlated spectral variability, while BL Lacs show little or none. All of this suggests that the high-energy continua of BL Lacs are beamed towards us, while the ultraviolet continua of Seyfert 1s are emitted isotropically.
The November 1991 multi-waveband monitoring of the BL Lac PKS 2155−304 showed strong correlated variability, with the soft X-rays leading the ultraviolet by a few hours, and no measurable lag between the ultraviolet and optical down to a limit of ≲ 1.5 hr. This indicates that the X-rays from this BL Lac are not produced by Compton upscattering, and that the ultraviolet does not come directly from a thermal source such as an accretion disk. This also strongly constrains the relativistic jet model, suggesting that all of the radiation is produced in a flattened region like a shock front.
Low temporal resolution ultraviolet/optical monitoring of the Seyfert 1 NGC 5548 in 1989 yielded a strong correlation with no measurable lag to a limit of ≲4 days, casting some doubt on the standard model of thermal emission from an accretion disk in Seyfert 1s. Upcoming X-ray/ultraviolet/optical monitoring of the Seyfert 1 NGC 4151 in December 1993 will have much faster sampling, to permit a strong test of both this model and the competing reprocessing model.
We present preliminary results on a combined HST/IUE/ground-based monitoring campaign on the Seyfert 1 galaxy NGC 5548 undertaken by the International AGN Watch in order to answer questions that require both high temporal resolution (one day) and high signal-to-noise ratios. Our preliminary conclusions are (1) the ultraviolet and optical continuum variations are simultaneous to within a day (2) the He II λ1640 variations lag behind the continuum by about 1.7 days, and (3) the velocity field of the C IV-emitting region is not characterized by bulk by radial motion, but the higher velocity gas seems to originate closer to the continuum source than the lower velocity gas.
Chickpea (Cicer arietinum L.) is an important food legume crop grown mostly in Asia and Africa as well as in other parts of the world, and serves as an important source of protein in the diets of vegetarian people. Lot of variation in grain quality traits has been observed in cultivated chickpea in both desi and Kabuli types. It has often been observed that seeds with smaller size have more protein when compared with those with larger size. The joint dependence of these two traits on the same primary characteristics results in this negative relationship. This negative correlation coupled with breeding efforts aimed at increasing grain yield has hampered the progress of improving these two traits simultaneously. Therefore, a germplasm exhibiting wider variability for these quantitative traits is an important resource for the identification of novel alleles. Herein, we report the wide variation observed for five important quantitative traits including days to flowering, days to maturity, plant height, 100-seed weight and protein content, and also report the significant positive correlation observed between 100-seed weight and protein content in a diverse collection of chickpea germplasm comprising both desi and Kabuli types.
Soybean is a leading oilseed crop in India, which contains about 40% of protein and 20% of oil. Core collection will accelerate the management and utilization of soybean genetic resources in breeding programmes. In the present study, eight agromorphological traits of 3443 soybean germplasm were analysed for the development of core collection using the principal component score (PCS) strategy and the power core method. The PCS strategy yielded core collection (CC1) of 576 accessions, which accounted for 16.72% of the entire collection (EC). The analysis based on the power core programme resulted in CC2 of 402 accessions, which accounted for 11.67% of the EC. Statistical analysis showed similar trends for the mean and range estimated in both core collections and EC. In addition, the variance, standard deviation and coefficient of variance were in general higher in core collections than in the EC. The correlations observed in the EC in general were preserved in core collections. A total of 311 and 137 unique accessions were found in CC1 and CC2 in addition to 265 accessions that were found to be common in both core collections. These 265 common accessions were the most diverse core sets, which accounted for 7.64% of the EC. We proposed to constitute an integrated core collection (ICC) by integrating both common and unique accessions. The ICC comprised 713 accessions, which accounted for about 20.62% of the EC. Statistical analysis indicated that the ICC captured maximum variation than CC1 and CC2. Therefore, the ICC can be extensively evaluated for a large number of economically important traits for the identification of desirable genotypes and for the development of mini core collection in soybean.