bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coexistence of perennial plants: an embarrassment of niches
Authors: Adler Peter B. , Ellner Stephen P. , Levine Jonathan M. 
Published: June 2010

Ecology Letters (2010) 13: 1019–1029AbstractDespite decades of research documenting niche differences between species, we lack a quantitative understanding of their effect on coexistence in natural communities. We perturbed an empirical sagebrush steppe community model to remove the demographic effect of niche differences and quantify their impact on coexistence. With stabilizing mechanisms operating, all species showed positive growth rates when rare, generating stable coexistence. Fluctuation‐independent mechanisms contributed more than temporal variability to coexistence and operated more strongly on recruitment than growth or survival. As expected, removal of stabilizing niche differences led to extinction of all inferior competitors. However, complete exclusion required 300–400 years, indicating small fitness differences among species. Our results show an ‘excess’ of niche differences: stabilizing mechanisms were not only strong enough to maintain diversity but were much stronger than necessary given the small fitness differences. The diversity of this community cannot be understood without consideration of niche differences.
The role of enemy release, tolerance and resistance in plant invasions: linking damage to performance
Authors: Chun Young Jin , Van Kleunen Mark , Dawson Wayne 
Published: June 2010

Ecology Letters (2010) 13: 937–946AbstractAn explanation for successful invasion is that invasive alien species sustain less pressure from natural enemies than co‐occurring native species. Using meta‐analysis, we examined whether invasive species: (1) incur less damage, (2) exhibit better performance in the presence of enemies, and (3) tolerate damage more than native species. Invasive alien species did not incur less damage than native species overall. The performance of invasive alien species was reduced compared to natives in the presence of enemies, indicating the invasive alien species were less tolerant to damage than native species. However, there was no overall difference in performance of invasive alien and native species with enemies present. The damage and degree of reduction in performance of invasive alien relative to native species did not depend on relatedness to natives. Our results suggest aliens may not always experience enemy release, and enemy release may not always result in greater plant performance.
Inoculum effects on community composition and nitritation performance of autotrophic nitrifying biofilm reactors with counter‐diffusion geometry
Authors: Terada Akihiko , Lackner Susanne , Kristensen Ken , Smets Barth F. 
Published: June 2010

SummaryThe link between nitritation success in a membrane‐aerated biofilm reactor (MABR) and the composition of the initial ammonia‐ and nitrite‐oxidizing bacterial (AOB and NOB) population was investigated. Four identically operated flat‐sheet type MABRs were initiated with two different inocula: from an autotrophic nitrifying bioreactor (Inoculum A) or from a municipal wastewater treatment plant (Inoculum B). Higher nitritation efficiencies (NO2‐‐N/NH4+‐N) were obtained in the Inoculum B‐ (55.2–56.4%) versus the Inoculum A‐ (20.2–22.1%) initiated reactors. The biofilms had similar oxygen penetration depths (100–150 µm), but the AOB profiles [based on 16S rRNA gene targeted real‐time quantitative PCR (qPCR)] revealed different peak densities at or distant from the membrane surface in the Inoculum B‐ versus A‐initiated reactors, respectively. Quantitative fluorescence in situ hybridization (FISH) revealed that the predominant AOB in the Inoculum A‐ and B‐initiated reactors were Nitrosospira spp. (48.9–61.2%) versus halophilic and halotolerant Nitrosomonas spp. (54.8–63.7%), respectively. The latter biofilm displayed a higher specific AOB activity than the former biofilm (1.65 fmol cell−1 h−1 versus 0.79 fmol cell−1 h−1). These observations suggest that the AOB and NOB population compositions of the inoculum may determine dominant AOB in the MABR biofilm, which in turn affects the degree of attainable nitritation in an MABR.
Painful foot drop; a presentation of diabetic muscle infarction
Authors: Karalliedde J. , Vijayanathan S. , Thomas S. 
Published: June 2010

Diabet. Med. 27, 958–959 (2010)AbstractBackground  Macro‐ and microvascular complications of diabetes are varied and can present with a range of clinical signs and symptoms. Diabetic muscle infarction is a rare vascular complication of diabetes that is often not recognized.Case report  We report a case of diabetic muscle infarction, where a 65‐year‐old woman with Type 2 diabetes presented with acute‐onset severe pain in her right leg and foot drop.Conclusions  Her foot drop was a result of a concomitant compression nerve injury as a consequence of the muscle oedema following infarction. Our case highlights the importance of early recognition and investigation of atypical presentations of vascular complications of diabetes.
What drives the positive correlation between human population density and bird species richness in Australia?
Authors: Luck Gary W. , Smallbone Lisa , McDonald Simon , Duffy Deanna 
Published: June 2010

ABSTRACTAim To test six hypotheses that could explain or mediate the positive correlation between human population density (HPD) and bird species richness while controlling for biased sampling effort. These hypotheses were labelled as follows: productivity (net primary productivity, NPP); inherent heterogeneity (diversity of vegetation types); anthropogenic heterogeneity (diversity of land uses); conservation policy (proportion of conservation land); increased productivity (human‐induced productivity increases); and the reduced‐slope hypothesis (which predicts that humans have a negative impact on species numbers across the full range of variation in HPD).Location Australia.Methods All data were collected at a spatial resolution of 1° across mainland Australia. Bird species richness was from 2007 atlas data and random subsampling was used to account for biased sampling effort. HPD was from the 2006 census. All other data were from government produced geographic information system layers. The most important biotic or abiotic factors influencing patterns in both species richness and HPD were assessed using simultaneous autoregressive models and an information theoretic approach.Results NPP appeared to be one of the main factors driving spatial congruence between bird species richness and HPD. Inherent habitat heterogeneity was weakly related to richness and HPD, although an interaction between heterogeneity and NPP indicated that the former may be an important determinant of species richness in low‐productivity regions. There was little evidence that anthropogenic landscape heterogeneity or human‐induced changes in productivity influenced the relationship between species richness and HPD, but conservation policy appeared to act as an important mediating factor and species richness was positively related to the proportion of conservation land only in regions of high HPD.Main conclusions The spatial congruence between bird species richness and HPD occurs because both respond positively to productivity and, in certain circumstances, habitat heterogeneity. Our results suggest that conservation policy could mediate this relationship, but further research is required to determine the importance of conservation reserves in supporting species in regions densely populated by humans.
Carbon dynamics of terrestrial ecosystems on the Tibetan Plateau during the 20th century: an analysis with a process‐based biogeochemical model
Authors: Zhuang Q. , He J. , Lu Y. , Ji L. , Xiao J. , Luo T. 
Published: June 2010

ABSTRACTAim  The Tibetan Plateau accounts for about a quarter of the total land area of China and has a variety of ecosystems ranging from alpine tundra to evergreen tropics. Its soils are dominated by permafrost and are rich in organic carbon. Its climate is unique due to the influence of the Asian monsoon and its complex topography. To date, the carbon dynamics of the Tibetan Plateau have not been well quantified under changes of climate and permafrost conditions. Here we use a process‐based biogeochemistry model, the Terrestrial Ecosystem Model (TEM), which was incorporated with a soil thermal model, to examine the permafrost dynamics and their effects on carbon dynamics on the plateau during the past century.Location  The Tibetan Plateau.Methods  We parameterize and verify the TEM using the existing data for soil temperature, permafrost distribution and carbon and nitrogen from the region. We then extrapolate the model and parameters to the whole plateau.Results  During the 20th century, the Tibetan Plateau changed from a small carbon source or neutral in the early part of the century to a sink later, with a large inter‐annual and spatial variability due to changes of climate and permafrost conditions. Net primary production and soil respiration increased by 0.52 and 0.22 Tg C year−1, respectively, resulting in a regional carbon sink increase of 0.3 Tg C year−1. By the end of the century, the regional carbon sink reached 36 Tg C year−1 and carbon storage in vegetation and soils is 32 and 16 Pg C, respectively. On the plateau, from west to east, the net primary production, soil respiration and net ecosystem production increased, due primarily to the increase of air temperature and precipitation and lowering elevation. In contrast, the decrease of carbon fluxes from south to north was primarily controlled by precipitation gradient. Dynamics of air temperature and associated soil temperature and active layer depth resulted in a higher plant carbon uptake than soil carbon release, strengthening the regional carbon sink during the century.Main conclusions  We found that increasing soil temperature and deepening active layer depth enhanced soil respiration, increasing the net nitrogen mineralization rate. Together with the effects of warming air temperature and rising CO2 concentrations on photosynthesis, the stronger plant nitrogen uptake due to the enhanced available nitrogen stimulates plant carbon uptake, thereby strengthening the regional carbon sink as the rate of increase net primary production was faster than that of soil respiration. Further, the warming and associated soil thermal dynamics shifted the regional carbon sink from the middle of July in the early 20th century to early July by the end of the century. Our study suggests that soil thermal dynamics should be considered for future quantification of carbon dynamics in this climate‐sensitive region.
Expanded view of the local–regional richness relationship by incorporating functional richness and time: a large‐scale perspective
Authors: Canning‐Clode João , Maloney Kelly O. , McMahon Sean M. , Wahl Martin 
Published: June 2010

ABSTRACTAim  We investigate the relationship between local and regional richness in marine fouling assemblages using an expanded and globally replicated approach by incorporating two dimensions of diversity (taxonomic and functional) and different successional stages.Location  Global.Methods  In eight different biogeographic regions (Australia, Brazil, Chile, England, Italy, Japan, Portugal and Sweden) 68 polyvinylchloride (PVC) panels (15 × 15 × 0.3 cm) were deployed for colonization. Communities colonizing panels were analysed by measuring percentage cover at each of four different successional ages: 2, 4, 6 and 8 months. Local richness was assessed as the average number of species and functional groups (FGs) per panel and regional richness was evaluated as the estimated (Jack2) asymptote of the sample‐accumulation curves for species and FG on experimental panels.Results  We found that the shape of the relationship between local and regional richness depended on successional stage and the type of richness considered, i.e. taxonomic or functional richness. Hardly any relationship was detectable between local taxonomic richness and regional taxonomic richness at any successional stage. In contrast, the relation between local functional and regional functional richness shows a unimodal pattern of change during succession, passing through the stages ‘independent’, ‘unsaturated rising’, ‘saturated rising’ and once again ‘independent’.Main conclusions  The relationship between local and regional richness, whether taxonomic or functional, frequently displays independence of the two scales, particularly in early and late phases of the successional process.
Weak climatic associations among British plant distributions
Authors: Chapman Daniel S. 
Published: June 2010

ABSTRACTAim Species distribution models (SDMs) are used to infer niche responses and predict climate change‐induced range shifts. However, their power to distinguish real and chance associations between spatially autocorrelated distribution and environmental data at continental scales has been questioned. Here this is investigated at a regional (10 km) scale by modelling the distributions of 100 plant species native to the UK.Location UK.Methods SDMs fitted using real climate data were compared with those utilizing simulated climate gradients. The simulated gradients preserve the exact values and spatial structure of the real ones, but have no causal relationships with any species and so represent an appropriate null model. SDMs were fitted as generalized linear models (GLMs) or by the Random Forest machine‐learning algorithm and were either non‐spatial or included spatially explicit trend surfaces or autocovariates as predictors.Results Species distributions were significantly but erroneously related to the simulated gradients in 86% of cases (P< 0.05 in likelihood‐ratio tests of GLMs), with the highest error for strongly autocorrelated species and gradients and when species occupied 50% of sites. Even more false effects were found when curvilinear responses were modelled, and this was not adequately mitigated in the spatially explicit models. Non‐spatial SDMs based on simulated climate data suggested that 70–80% of the apparent explanatory power of the real data could be attributable to its spatial structure. Furthermore, the niche component of spatially explicit SDMs did not significantly contribute to model fit in most species.Main conclusions Spatial structure in the climate, rather than functional relationships with species distributions, may account for much of the apparent fit and predictive power of SDMs. Failure to account for this means that the evidence for climatic limitation of species distributions may have been overstated. As such, predicted regional‐ and national‐scale impacts of climate change based on the analysis of static distribution snapshots will require re‐evaluation.
Hidden patterns of phylogenetic non‐stationarity overwhelm comparative analyses of niche conservatism and divergence
Authors: Diniz‐Filho José Alexandre Felizola , Terribile Levi Carina , da Cruz Mary Joice Ribeiro , Vieira Ludgero Cardoso G. 
Published: June 2010

ABSTRACTAim Despite the importance of the niche concept in ecological and evolutionary theory, there are still many discussions about its definition and operational evaluation, especially when dealing with niche divergence and conservatism in an explicit phylogenetic context. Here we evaluate patterns of niche evolution in 67 New World Carnivora species, measured using Hellinger distances based on MAXENT models of species distribution. We show how inferences on niche conservatism or divergence depend on the way phylogenetic patterns are analysed using matrix comparison techniques.Innovation Initially we used the simplest approach of Mantel tests to compare Hellinger distances (N) derived from MAXENT and phylogenetic distances (P) among species. Then we extended the Mantel test to generate a multivariate correlogram, in which phylogenetic patterns are analysed at multiple levels in the phylogeny and can reveal nonlinearity in the relationship between divergence and time. Finally, we proposed a new approach to generate ‘local’ (or ‘specific’) leverages of components for Mantel correlation, evaluating the non‐stationarity in the relationship betweenNandPfor each species. This new approach was used to show if some lineages are more prone to niche shift or conservatism than others.Main conclusions Standard Mantel tests indicated a poor correspondence betweenNandPmatrices, discarding the idea of niche conservatism for Carnivora, but the correlogram supports that closely related species tend to be more similar than expected by chance. Moreover, the variance among Hellinger distances between pairs of closely phylogenetically related species is much larger than for the entire clade. Phylogenetic non‐stationarity analysis shows that in some Carnivora families the niche tends to divergence (Mustelidae and Canidae), whereas in others it tends to conservatism (Procyonidae and Mustelidae) at short phylogenetic distances. Our analyses clearly show that misleading results may appear if niche divergence is analysed only by simple matrix correlations not taking into account complex patterns of phylogenetic nonlinearity and non‐stationarity.
The prevalence and trends of overweight, obesity and nutrition‐related non‐communicable diseases in the Arabian Gulf States
Authors: Ng S. W. , Zaghloul S. , Ali H. I. , Harrison G. , Popkin B. M. 
Published: June 2010

SummaryThis paper reviews studies on the prevalence of overweight, obesity and related nutrition‐related non‐communicable diseases in Bahrain, Kuwait, Qatar, Oman, Saudi Arabia and the UAE. Obesity is common among women; while men have an equal or higher overweight prevalence. Among adults, overweight plus obesity rates are especially high in Kuwait, Qatar and Saudi Arabia, and especially among 30–60 year olds (70–85% among men; 75–88% among women), with lower levels among younger and elderly adults. The rate of increase in obesity was pronounced in Saudi Arabia and Kuwait. Prevalence of obesity is high among Kuwaiti and Saudi pre‐schoolers (8–9%), while adolescent overweight and obesity are among the highest in the world, with Kuwait having the worst estimates (40–46%); however, comparison of child data is difficult because of differing standards. Among nutrition‐related non‐communicable diseases, hypertension and diabetes levels are very high and increase with age, with the UAE performing the worst because of a rapid rate of increase between 1995 and 2000. Additional monitoring of the prevalence of metabolic syndrome and cancers is necessary. Nationally representative longitudinal surveys with individual, household and community‐level information are needed to determine the importance of various factors that contribute to these troubling trends.
Relative Risk Estimated from the Ratio of Two Median Unbiased Estimates
Authors: Carter Rickey E. , Lin Yan , Lipsitz Stuart R. , Newcombe Robert G. , Hermayer Kathie L. 
Published: June 2010

SummaryClinical trials often include binary end points. In some cases, no successes are observed and the usual large sample estimates of relative risk are undefined. The paper proposes an estimator for relative risk based on the median unbiased estimator. The relative risk estimator proposed is well defined and performs satisfactorily for a wide range of data configurations. To facilitate the use of the estimator, a deterministic bootstrap confidence interval is also proposed, and an SAS macro is available to perform the necessary calculations. An on-going randomized clinical trial motivated the development of the estimator and is used to illustrate the approach.
An Application of Hidden Markov Models to the French Variant Creutzfeldt–Jakob Disease Epidemic
Authors: Chadeau-Hyam Marc , Clarke Paul S. , Guihenneuc-Jouyaux Chantal , Cousens Simon N. , Will Robert G. , Ghani Azra C. 
Published: June 2010

SummaryIn 1996, the discovery of variant Creutzfeldt–Jakob disease in the UK raised serious concerns about a large-scale epidemic. These concerns have been heightened by the recent discovery of people in Britain who were infected through blood transfusion. The outbreak of variant Creutzfeldt–Jakob disease in France emerged more recently with 23 cases observed to date. We use a hidden Markov model to predict the scale of the epidemic in France. As accurate data on the most important epidemiological parameters are scarce, we incorporate estimates from previous studies. Parameter estimation is performed by using Markov chain Monte Carlo methods from which credible intervals for our predictions are obtained. The sensitivity of these predictions to important assumptions regarding population exposure is assessed.
15. The Breeding Habits of the Angel‐Fish (Pteroyhyllum scalare)
Authors: Sladden Dorothy E. 
Published: June 2010

Summary.Amazon Angel‐fish (Pterophyllum scalare) bred in the Zoological Society's Aquarium for the first time in June 1936. The spawning took place in a 50‐gallon tank at a temperature ranging from 80 to 82°° F., and in slightly acid water, pH 6.8. Markings on the head and body of the male, which may be an indication that it is in breeding condition, were observed. 150–200 eggs were deposited, 45–50 young hatched, and of these 30 per cent. were reared. Both parents took part in caring for the young. On hatching, the fry resembled the young of other Cichlids, but at the age of one month the typical adult form was assumed.
Initial Clinical Experience With the HeartMate II Ventricular Assist System in a Pediatric Institution
Authors: Owens William R. , Bryant III Roosevelt , Dreyer William J. , Price Jack F. , Morales David L.S. 
Published: June 2010

AbstractIn many adult cardiac programs, intracorporeal mechanical circulatory support has become a routine treatment for end‐stage cardiac failure. For the pediatric population, options are often limited by a small body habitus. Even when an adolescent's weight may suggest adequate space for device implant, most intracorporeal adult devices remain too large for adolescents. The Thoratec HeartMate II (HM II) (approved by the FDA in April of 2008) is a small, noiseless device that is easily operated and monitored. By having an uncomplicated operating system and small percutaneous drive line, the HM II provides an opportunity for these patients to aggressively rehabilitate to become a better transplant candidate and also provides the potential to be discharged home. The two youngest patients ever to utilize the HM II are also the first two cases of using the HM II at a freestanding pediatric hospital. A 12‐year‐old, 53 kg, girl with dilated cardiomyopathy was supported for 85 days before receiving her heart transplant. The second patient, a 13‐year‐old, 149 kg, Hispanic male suffering from morbid obesity and dilated cardiomyopathy, was supported for 128 days. The HM II allowed for rehabilitation and nutritional education, resulting in this patient losing 50 kg before heart transplant. Despite both of these patients' size, their thoracic cavities were that of a preadolescent and thus techniques were developed to avoid morbidities like chest wall abrasion and bleeding. Because of differences between adult and pediatric patients and institutions, these cases provided unique challenges. However, as pediatric device therapy is now maturing, pediatric programs such as Texas Children's Hospital have begun to develop strategies for mechanical support that factor in patient's size and need for long‐term or temporary support, utilizing the growing number of devices (i.e., Jostra Rotoflow, Tandem Heart PTVA, Thoratec CentriMag, Berlin Heart EXCOR, etc.) that are now available to children.