bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of drops of surfactant solutions on small targets
Authors: Rozhkov A. , Prunet-Foch B. , Vignes-Adler M.
Published: April 2010

The collisions of drops of surfactant solutions (dioctyl sulfosuccinate sodium salt (DOS) and trisiloxane oxypropylene polyoxyethylene (Silwett L77)) with small disc-like targets were studied both experimentally and theoretically. Upon impact, the drops spread very fast beyond the target in the shape of a thin lamella surrounded by a thick rim. No significant difference between water and surfactant solutions was observed in the early stage of the impact. But the collapse stages were very different. In particular, the lamellas of solutions of Silwett L77 disintegrated owing to a spontaneous nucleation of holes, giving to the lamella a web-like structure prior to its break-up. In contrast, lamellas of DOS solutions collapsed like water lamellas, except that the maximum diameter and the lifetime of the lamella of the most concentrated DOS solution were significantly increased compared with pure water and other surfactant solutions. A theoretical analysis shows that the observed instability effects in the lamella and the increase in the size and lifetime of the lamella can be caused by the coupling between liquid inertia and Marangoni stresses.
Exponential asymptotics and boundary-value problems: keeping both sides happy at all orders
Authors: Howls C. J.
Published: April 2010

We introduce templates for exponential-asymptotic expansions that, in contrast to matched asymptotic approaches, enable the simultaneous satisfaction of both boundary values in classes of linear and nonlinear equations that are singularly perturbed with an asymptotic parameter

and have a single boundary layer at one end of the interval. For linear equations, the template is a transseries that takes the form of a sliding ladder of exponential scales. For nonlinear equations, the transseries template is a two-dimensional array of exponential scales that tilts and realigns asymptotic balances as the interval is traversed. An exponential-asymptotic approach also reveals how boundary-value problems force the surprising presence of transseries in the linear case and negative powers of
ϵ
terms in the series beyond all orders in the nonlinear case. We also demonstrate how these transseries can be resummed to generate multiple-scales-type approximations that can generate uniformly better approximations to the exact solution out to larger values of the perturbation parameter. Finally, we show for a specific example how a reordering of the terms in the exponential asymptotics can lead to an acceleration of the accuracy of a truncated expansion.
Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (
Megaptera novaeangliae
)
Authors: Dunlop Rebecca A. , Cato Douglas H. , Noad Michael J.
Published: April 2010

High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as ‘breaching’ or ‘pectoral slapping’. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this information in a noisy environment. Surface-generated sounds have energy distributed over a greater frequency range and may be less likely to become confused in periods of high wind-generated noise but have less information content when compared with vocal sounds. Therefore, surface-generated sounds may improve detection or enhance the perception of vocal signals in a noisy environment.
Inferred relatedness and heritability in malaria parasites
Authors: Anderson Tim J. C. , Williams Jeff T. , Nair Shalini , Sudimack Daniel , Barends Marion , Jaidee Anchalee , Price Ric N. , Nosten François
Published: April 2010

Malaria parasites vary in phenotypic traits of biomedical or biological interest such as growth rate, virulence, sex ratio and drug resistance, and there is considerable interest in identifying the genes that underlie this variation. An important first step is to determine trait heritability (
H
2
). We evaluate two approaches to measuring
H
2
in natural parasite populations using relatedness inferred from genetic marker data. We collected single-clone
Plasmodium falciparum
infections from 185 patients from the Thailand–Burma border, monitored parasite clearance following treatment with artemisinin combination therapy (ACT), measured resistance to six antimalarial drugs and genotyped parasites using 335 microsatellites. We found strong relatedness structure. There were 27 groups of two to eight clonally identical (CI) parasites, and 74 per cent of parasites showed significant relatedness to one or more other parasites. Initially, we used matrices of allele sharing and variance components (VC) methods to estimate
H
2
. Inhibitory concentrations (IC
50
) for six drugs showed significant
H
2
(0.24 to 0.79,
p
= 0.06 to 2.85 × 10
−9
), demonstrating that this study design has adequate power. However, a phenotype of current interest—parasite clearance following ACT—showed no detectable heritability (
H

2

=
0–0.09, ns) in this population. The existence of CI parasites allows the use of a simple ANOVA approach for quantifying
H
2
, analogous to that used in human twin studies. This gave similar results to the VC method and requires considerably less genotyping information. We conclude (i) that
H
2
can be effectively measured in malaria parasite populations using minimal genotype data, allowing rational design of genome-wide association studies; and (ii) while drug response (IC
50
) shows significant
H
2
, parasite clearance following ACT was not heritable in the population studied.
Elevated CO2affects shell dissolution rate but not calcification rate in a marine snail
Authors: Nienhuis Sarah , Palmer A. Richard , Harley Christopher D. G.
Published: April 2010

As CO2levels increase in the atmosphere, so too do they in the sea. Although direct effects of moderately elevated CO2in sea water may be of little consequence, indirect effects may be profound. For example, lowered pH and calcium carbonate saturation states may influence both deposition and dissolution rates of mineralized skeletons in many marine organisms. The relative impact of elevated CO2on deposition and dissolution rates are not known for many large-bodied organisms. We therefore tested the effects of increased CO2levels—those forecast to occur in roughly 100 and 200 years—on both shell deposition rate and shell dissolution rate in a rocky intertidal snail,Nucella lamellosa. Shell weight gain per day in live snails decreased linearly with increasing CO2levels. However, this trend was paralleled by shell weight loss per day in empty shells, suggesting that these declines in shell weight gain observed in live snails were due to increased dissolution of existing shell material, rather than reduced production of new shell material. Ocean acidification may therefore have a greater effect on shell dissolution than on shell deposition, at least in temperate marine molluscs.
Cell formation by myxozoan species is not explained by dogma
Authors: Morris David J.
Published: April 2010

Eukaryotes form new cells through the replication of nuclei followed by cytokinesis. A notable exception is reported from the class Myxosporea of the phylum Myxozoa. This assemblage of approximately 2310 species is regarded as either basal bilaterian or cnidarian, depending on the phylogenetic analysis employed. For myxosporeans, cells have long been regarded as forming within other cells by a process referred to as endogenous budding. This would involve a nucleus forming endoplasmic reticulum around it, which transforms into a new plasma membrane, thus enclosing and separating it from the surrounding cell. This remarkable process, unique within the Metazoa, is accepted as occurring within stages found in vertebrate hosts, but has only been inferred from those stages observed within invertebrate hosts. Therefore, I conducted an ultrastructural study to examine how internal cells are formed by a myxosporean parasitizing an annelid. In this case, actinospore parasite stages clearly internalized existing cells; a process with analogies to the acquisition of endosymbiotic algae by cnidarian species. A subsequent examination of the myxozoan literature did not support endogenous budding, indicating that this process, which has been a central tenet of myxozoan developmental biology for over a century, is dogma.
Paternal levels of DNA damage in spermatozoa and maternal parity influence offspring mortality in an endangered ungulate
Authors: Ruiz-López María José , Espeso Gerardo , Evenson Donald P. , Roldan Eduardo R. S. , Gomendio Montserrat
Published: April 2010

Understanding which factors influence offspring mortality rates is a major challenge since it influences population dynamics and may constrain the chances of recovery among endangered species. Most studies have focused on the effects of maternal and environmental factors, but little is known about paternal factors. Among most polygynous mammals, males only contribute the haploid genome to their offspring, but the possibility that sperm DNA integrity may influence offspring survival has not been explored. We examined several maternal, paternal and individual factors that may influence offspring survival in an endangered species (
Gazella cuvieri
). Levels of sperm DNA damage had the largest impact upon offspring mortality rates, followed by maternal parity. In addition, there was a significant interaction between these two variables, so that offspring born to primiparous mothers were more likely to die if their father had high levels of sperm DNA damage, but this was not the case among multiparous mothers. Thus, multiparous mothers seem to protect their offspring from the deleterious effects of sperm DNA damage. Since levels of sperm DNA damage seem to be higher among endangered species, more attention should be paid to the impact of this largely ignored factor among the viability of endangered species.
Global drivers of human pathogen richness and prevalence
Authors: Dunn Robert R. , Davies T. Jonathan , Harris Nyeema C. , Gavin Michael C.
Published: April 2010

The differences in the richness and prevalence of human pathogens among different geographical locations have ramifying consequences for societies and individuals. The relative contributions of different factors to these patterns, however, have not been fully resolved. We conduct a global analysis of the relative influence of climate, alternative host diversity and spending on disease prevention on modern patterns in the richness and prevalence of human pathogens. Pathogen richness (number of kinds) is largely explained by the number of birds and mammal species in a region. The most diverse countries with respect to birds and mammals are also the most diverse with respect to pathogens. Importantly, for human health, the prevalence of key human pathogens (number of cases) is strongly influenced by disease control efforts. As a consequence, even where disease richness is high, we might still control prevalence, particularly if we spend money in those regions where current spending is low, prevalence is high and populations are large.
A spitting image: specializations in archerfish eyes for vision at the interface between air and water
Authors: Temple Shelby , Hart Nathan S. , Marshall N. Justin , Collin Shaun P.
Published: April 2010

Archerfish are famous for spitting jets of water to capture terrestrial insects, a task that not only requires oral dexterity, but also the ability to detect small camouflaged prey against a visually complex background of overhanging foliage. Because detection of olfactory, auditory and tactile cues is diminished at air–water interfaces, archerfish must depend almost entirely on visual cues to mediate their sensory interactions with the aerial world. During spitting, their eyes remain below the water's surface and must adapt to the optical demands of both aquatic and aerial fields of view. These challenges suggest that archerfish eyes may be specially adapted to life at the interface between air and water. Using microspectrophotometry to characterize the spectral absorbance of photoreceptors, we find that archerfish have differentially tuned their rods and cones across their retina, correlated with spectral differences in aquatic and aerial fields of view. Spatial resolving power also differs for aquatic and aerial fields of view with maximum visual resolution (6.9 cycles per degree) aligned with their preferred spitting angle. These measurements provide insight into the functional significance of intraretinal variability in archerfish and infer intraretinal variability may be expected among surface fishes or vertebrates where different fields of view vary markedly.
Does signalling mitigate the cost of agonistic interactions? A test in a cricket that has lost its song
Authors: Logue D. M. , Abiola I. O. , Rains D. , Bailey N. W. , Zuk M. , Cade W. H.
Published: April 2010

Prevailing models of animal communication assume that signalling during aggressive conflict mitigates the costs of fighting. We tested this assumption by staging dyadic encounters between male field crickets,
Teleogryllus oceanicus
, under three conditions: (i) both males could sing aggressive songs, (ii) neither male could sing, and (iii) one male could sing but the other could not. We conducted experiments on males from a Hawaiian population from Kauai that has recently evolved signal loss, and males from a Hawaiian population from the Big Island that has not. Among both populations, interactions between two silent males were characterized by higher levels of aggression than interactions involving one or two singing males. Because the level of aggression is strongly related to the cost of fighting, these data demonstrate that signalling mitigates the cost of fighting. In mixed trials, we found no statistically significant differences between the behaviour of calling and non-calling males in either population. We conclude that there is no evidence that the Kauai population exhibits special adaptations to alleviate the costs of signal loss. Finally, we found that males were much more likely to signal after their opponent's retreat than after their own retreat. Aggressive song therefore meets the definition of a ‘victory display’.
An analysis of clustering of betapapillomavirus antibodies
Authors: Mallitt K. A. , O'Rourke P. , Bouwes Bavinck J. N. , Abeni D. , de Koning M. N. C. , Feltkamp M. C. W. , Green A. C. , Quint W. G. V. , Michael K. M. , Pawlita M. , Pfister H. , Weissenborn S. , Waterboer T. , Neale R. E. ,   the EPI-HPV-UV-CA Group
Published: April 2010

Betapapillomaviruses (βPVs) may contribute to the aetiology of cutaneous squamous cell carcinoma. However, no high-risk types have yet been identified, possibly because the high frequency of co-infection prevents a straightforward analysis of the independent effects of individual viruses. This study aimed to determine whether specific virus types were more likely to co-occur than others, thereby reducing the number of parameters needed in statistical models. Antibody data were analysed from controls who participated in case–control studies in The Netherlands, Italy and Australia and from participants in the German Nutrition Survey. Cluster analysis and two ordination techniques were used to identify patterns. Evidence of clustering was found only according to the number of viruses to which antibodies were detected. The lack of clustering of specific viral types identified suggests that if there are βPV types that are independently related to skin carcinogenesis, they are unlikely to be identified using standard epidemiological methods.
Death mechanisms in epithelial cells following rotavirus infection, exposure to inactivated rotavirus or genome transfection
Authors: Halasz Peter , Holloway Gavan , Coulson Barbara S.
Published: April 2010

Intestinal epithelial cell death following rotavirus infection is associated with villus atrophy and gastroenteritis. Roles for both apoptosis and necrosis in cytocidal activity within rotavirus-infected epithelial cells have been proposed. Additionally, inactivated rotavirus has been reported to induce diarrhoea in infant mice. We further examined the death mechanisms induced in epithelial cell lines following rotavirus infection or inactivated rotavirus exposure. Monolayer integrity changes in MA104, HT-29 and partially differentiated Caco-2 cells following inactivated rotavirus exposure or RRV or CRW-8 rotavirus infection paralleled cell metabolic activity and viability reductions. MA104 cell exposure to rotavirus dsRNA also altered monolayer integrity. Inactivated rotaviruses induced delayed cell function losses that were unrelated to apoptosis. Phosphatidylserine externalization, indicating early apoptosis, occurred in MA104 and HT-29 but not in partially differentiated Caco-2 cells by 11 h after infection. Rotavirus activation of phosphatidylinositol 3-kinase partially protected MA104 and HT-29 cells from early apoptosis. In contrast, activation of the stress-activated protein kinase JNK by rotavirus did not influence apoptosis induction in these cells. RRV infection produced DNA fragmentation, indicating late-stage apoptosis, in fully differentiated Caco-2 cells only. These studies show that the apoptosis initiation and cell death mechanism induced by rotavirus infection depend on cell type and degree of differentiation. Early stage apoptosis resulting from rotavirus infection is probably counter-balanced by virus-induced phosphatidylinositol 3-kinase activation. The ability of inactivated rotaviruses and rotavirus dsRNA to perturb monolayer integrity supports a potential role for these rotavirus components in disease pathogenesis.
Characterization of atypical scrapie cases from Great Britain in transgenic ovine PrP mice
Authors: Griffiths Peter C. , Spiropoulos John , Lockey Richard , Tout Anna C. , Jayasena Dhanushka , Plater Jane M. , Chave Alun , Green Robert B. , Simonini Sarah , Thorne Leigh , Dexter Ian , Balkema-Buschmann Anne , Groschup Martin H. , Béringue Vincent , Le Dur Annick , Laude Hubert , Hope James
Published: April 2010

Twenty-four atypical scrapie cases from sheep with different prion protein genotypes from Great Britain were transmitted to transgenic tg338 and/or TgshpXI mice expressing sheep PrP alleles, but failed to transmit to wild-type mice. Mean incubation periods were 200–300 days in tg338 mice and 300–500 days in TgshpXI mice. Survival times in C57BL/6 and VM/Dk mice were >700 days. Western blot analysis of mouse brain samples revealed similar multi-band, protease-resistant prion protein (PrPres) profiles, including an unglycosylated band at ∼8–11 kDa, which was shown by antibody mapping to correspond to the ∼93–148 aa portion of the PrP molecule. In transgenic mice, the incubation periods, Western blot PrPres profiles, brain lesion profiles and abnormal PrP (PrPSc) distribution patterns produced by the Great Britain atypical scrapie isolates were similar and compatible with the biological characteristics of other European atypical scrapie or Nor98 cases.
Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement
Authors: Lim Hyoun-Sub , Vaira Anna Maria , Bae Hanhong , Bragg Jennifer N. , Ruzin Steven E. , Bauchan Gary R. , Dienelt Margaret M. , Owens Robert A. , Hammond John
Published: April 2010

Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells. Deletion and site-specific mutagenesis revealed an internal signal VL(17,18) of TGB3 essential for chloroplast localization, and either deletion of the TGB3 start codon or alteration of the chloroplast-localization signal limited cell-to-cell movement to the epidermis, yielding a virus that was unable to move into the mesophyll layer. Overexpression of AltMV TGB3 from either AltMV or PVX infectious clones resulted in veinal necrosis and vesiculation at the chloroplast membrane, a cytopathology not observed in wild-type infections. The distinctive mesophyll and chloroplast localization of AltMV TGB3 highlights the critical role played by mesophyll targeting in virus long-distance movement within plants.
Evolution of highly pathogenic avian H5N1 influenza viruses and the emergence of dominant variants
Authors: Neumann Gabriele , Green Margaret A. , Macken Catherine A.
Published: April 2010

Highly pathogenic avian H5N1 viruses have circulated in South-east Asia for more than a decade and have now spread to more than 60 countries. The evolution of these viruses is characterized by frequent reassortment of the so-called ‘internal’ genes, creating novel genotypes. Additionally, over time, the surface glycoprotein, haemagglutinin (HA), which is the primary target of the adaptive immune response, has evolved by point mutation into 20 genetically and potentially antigenically distinct clades. To investigate the evolution of avian H5N1 influenza viruses, we undertook a high-resolution analysis of the reassortment of internal genes and evolution of HA of 651 avian H5N1 viruses from 2000 to 2008. Our analysis suggested: (i) all current H5N1 genotypes were derived from a single, clearly defined sequence of initial reassortment events; (ii) reassortment of just three of the internal genes had the most importance in avian H5N1 virus evolution; (iii) HA and the constellation of internal genes may be jointly important in the emergence of dominant variants. Further, our analysis led to the identification of evolutionarily significant molecular changes in the internal genes that may be significant for the emergence of these dominant variants.
Characterization of H5N2 influenza viruses isolated in South Korea and their influence on the emergence of a novel H9N2 influenza virus
Authors: Kim Hye-Ryoung , Park Choi-Ku , Oem Jae-Ku , Bae You-Chan , Choi Jun-Gu , Lee O-Soo , Lee Youn-Jeong
Published: April 2010

We characterized low pathogenic avian influenza (LPAI) H5N2 and H9N2 viruses isolated in South Korea from 2008 to 2009. Genetic analysis of the H5N2 viruses isolated from wild birds and domestic ducks demonstrated that they were related to the recently isolated southern Chinese LPAI H5 viruses and various influenza viruses circulating in Eurasia. Three H9N2 viruses obtained at live bird markets and duck farms were reassortant viruses generated from the H5N2 viruses of domestic ducks and the H9N2 virus endemic in Korean chickens. The H5N2 viruses did not replicate well in experimentally infected chickens and mice, but novel H9N2 viruses, without pre-adaptation, were recovered at high titres in chickens. Our results show that reassortment between H5N2 and H9N2 viruses must have occurred in domestic ducks and may have contributed to the diversity expansion of the gene pool, which has potential to alter the pathogenicity and host range of the influenza virus.
A wheel of time: the circadian clock, nuclear receptors, and physiology: Figure 1.
Authors: Yang Xiaoyong
Published: April 2010

It is a long-standing view that the circadian clock functions to proactively align internal physiology with the 24-h rotation of the earth. Recent studies, including one by Schmutz and colleagues (pp. 345–357) in the February 15, 2010, issue of Genes & Development, delineate strikingly complex connections between molecular clocks and nuclear receptor signaling pathways, implying the existence of a large-scale circadian regulatory network coordinating a diverse array of physiological processes to maintain dynamic homeostasis.
The spatial dynamics of tissue-specific promoters during C. elegans development
Authors: Meister Peter , Towbin Benjamin D. , Pike Brietta L. , Ponti Aaron , Gasser Susan M.
Published: April 2010

To understand whether the spatial organization of the genome reflects the cell's differentiated state, we examined whether genes assume specific subnuclear positions during Caenorhabditis elegans development. Monitoring the radial position of developmentally controlled promoters in embryos and larval tissues, we found that small integrated arrays bearing three different tissue-specific promoters have no preferential position in nuclei of undifferentiated embryos. However, in differentiated cells, they shifted stably toward the nuclear lumen when activated, or to the nuclear envelope when silent. In contrast, large integrated arrays bearing the same promoters became heterochromatic and nuclear envelope-bound in embryos. Tissue-specific activation of promoters in these large arrays in larvae overrode the perinuclear anchorage. For transgenes that carry both active and inactive promoters, the inward shift of the active promoter was dominant. Finally, induction of master regulator HLH-1 prematurely induced internalization of a muscle-specific promoter array in embryos. Fluorescence in situ hybridization confirmed analogous results for the endogenous endoderm-determining gene pha-4. We propose that, in differentiated cells, subnuclear organization arises from the selective positioning of active and inactive developmentally regulated promoters. We characterize two forces that lead to tissue-specific subnuclear organization of the worm genome: large repeat-induced heterochromatin, which associates with the nuclear envelope like repressed genes in differentiated cells, and tissue-specific promoters that shift inward in a dominant fashion over silent promoters, when they are activated.
Status of forests in Uganda
Authors: Obua Joseph , Agea Jacob G. , Ogwal Joseph Jones
Published: April 2010

Trees, forests and woodlands cover about 14% of Uganda’s land surface. Over the last 30–40 years, growth in human population and corresponding increase in demand for forest products for domestic and industrial use, expansion of agricultural land, illegal settlements and weak forest management capacity have adversely affected the status of natural forests in Uganda, particularly the biodiversity. Until recently, little attention had been paid to development of commercial forests which should have provided alternative forest products and services to relieve the pressure on natural forests and conserve biodiversity. As a result, Uganda’s forests have been degraded, and in some cases, the biodiversity has been eroded. There is a need for regular data collection and monitoring of the status of the forests in terms of areal extent, distribution, plantation species introductions and biodiversity.
The relationship between Developmental Co‐ordination Disorders, child's perceived self‐efficacy and preference to participate in daily activities
Authors: Engel‐Yeger B. , Hanna Kasis A.
Published: April 2010

Background  Developmental Co‐ordination Disorder (DCD) may negatively impact children's self‐efficacy and limit their performance and participation in school as well as in leisure activities performed after school hours. However, a lack of information exists regarding the relationships between DCD, child's self‐efficacy and participation. Moreover, the literature about the way children with DCD experience these limitations and report about them is scarce. This study aimed to compare the perceived self‐efficacy and the preference to participate in leisure activities of children with DCD and typical peers and to illuminate the relationship between self‐efficacy, activity preference and DCD severity.

Methods  Participants were 37 children with DCD and 37 typical peers, aged 5.08–9.83 years. All children performed the Movement Assessment Battery for Children, the Perceived Efficacy and Goal Setting System and the Preference for Activities of Children.

Results  The scores of the Movement Assessment Battery for Children confirmed the motor gaps between the two groups. Children with DCD scored significantly lower in self‐efficacy on all the Perceived Efficacy and Goal Setting System subscales and demonstrated a lower preference to participate in leisure activities according to all scales of the Preference for Activities of Children. The lower their self‐efficacy, the lower their motor performance and their preference to participate in activities.

Conclusions  Children's preference to participate in activities may be limited by motor difficulties, but further hindered by low self‐efficacy. Early identification of DCD and associated negative outcomes, also based on child's self‐reports, should receive special attention in intervention programmes in order to enhance children's self‐confidence, feelings of belonging, optimal development and participation in daily activities.
Out‐of‐school time activity participation profiles of children with physical disabilities: a cluster analysis
Authors: King G. , Petrenchik T. , DeWit D. , McDougall J. , Hurley P. , Law M.
Published: April 2010

Objective To determine out‐of‐school activity participation profiles of school‐aged children with physical disabilities.

Methods Activity participation profiles were determined by cluster analysing 427 children's responses on multiple dimensions of participation (intensity, location, companionship, enjoyment, preference) in five activity types (recreational, active physical, social, skill‐based, self‐improvement). Socio‐demographic, child, parent, family and environmental predictors of group membership were determined, along with child functioning, socio‐demographic, self‐concept and social support variables significantly associated with group membership.

Results The cluster analysis revealed four groups, labelled Social Participators (a highly social and neighbourhood‐focused group), Broad Participators (a group of high participators who enjoy participation), Low Participators (a group with low enjoyment and weak preferences) and Recreational Participators (a group of younger children who participate in recreational activities with family members). The groups showed meaningful differences across a range of socio‐demographic, child, parent, family and environmental variables.

Conclusions The findings support an affective and contextual view of participation, indicating the importance of motivational theory and a person–environment approach in understanding the complexity of children's out‐of‐school activity participation.
Pre‐operative platelet‐bound CD40 ligand is probably associated with peri‐operative cardiac events in hip and knee arthroplasty
Authors: Ray Michael J. , Calabro Lorenzo J. , Sirisena Tilak , Crawford Scott A. , Crawford Ross W. , Walters Darren L.
Published: April 2010

Eur J Clin Invest 2010; 40 (6): 497–503

Background  Peri‐operative cardiac events are common and associated with significant morbidity. A predictive biomarker would assist in pre‐operative risk stratification of surgical patients. This study explored the utility of pre‐operative measurements of platelet‐bound CD40 ligand and other biomarkers for predicting peri‐operative cardiac events in total hip or knee arthroplasty.

Methods  Blood samples were collected from 62 patients prior to surgery and tested for the biomarkers platelet CD40 ligand, platelet factor V/Va, platelet P‐selectin, high‐sensitivity C‐reactive protein, B‐type natriuretic peptide and soluble CD40 ligand. The Revised Cardiac Risk Index was also calculated. Patients were then followed up prospectively and screened for peri‐operative cardiac events by means of ECG, serial troponin I, a cardiologist’s review and an interview at 6 weeks post operation.

Results  Six of 62 (9·7%) patients had a cardiac event. Patients who experienced a cardiac event had higher pre‐operative platelet CD40 ligand levels as measured by flow cytometry [median 0·55% vs. 0·29% (P = 0·02)]. In this sized sample, platelet CD40L was the only biomarker independently associated with cardiac events (P = 0·02), the area under the receiver–operator characteristic curve being 0·79.

Conclusion  In a study of this number of patients, of the six biomarkers tested, only platelet CD40 ligand was found to have a probable association with peri‐operative cardiac events in hip and knee arthroplasty.
Distribution of small intestinal mucosal injuries as a result of NSAID administration
Authors: Fujimori Shunji , Gudis Katya , Takahashi Yoko , Seo Tsuguhiko , Yamada Yukie , Ehara Akihito , Kobayashi Tsuyoshi , Mitsui Keigo , Yonezawa Masaoki , Tanaka Shu , Tatsuguchi Atsushi , Sakamoto Choitsu
Published: April 2010

Eur J Clin Invest 2010; 40 (6): 504–510

Background  Nonsteroidal anti‐inflammatory drugs (NSAIDs) induce small intestinal mucosal injuries. The concentrations of NSAIDs, bile acids and intestinal flora may differ in the proximal and distal parts of the small intestine. This study aimed to analyse types and distributions of NSAID‐induced small intestinal injuries.

Subjects and methods  In total 55 healthy male volunteers were examined using baseline capsule endoscopy (CE). Subjects then undertook a 14‐day regimen of NSAID medication (diclofenac sodium, 75 mg day−1) with proton‐pump inhibitors (omeprazole 20 mg day−1) as gastroprotection. After 14 days, subjects underwent post‐treatment CE and were assessed for three types of small intestinal injuries: denuded areas, erosions and ulcers. The proximal and distal parts of the small intestine were arbitrarily classified according to CE transit time from the duodenal bulb.

Results  Baseline CE revealed six mucosal lesions in 6 of 55 subjects (11%), consisting of three denuded areas and three erosions. Post‐treatment CE identified 636 lesions in 32 of 53 subjects (60%); including 115 denuded areas in 16 subjects, 498 erosions in 22 subjects and 23 ulcers in 8 subjects. The distribution of small intestinal injuries differed according to type; denuded areas (90%: 103/115) were predominantly located in the proximal part, erosions throughout the small intestine and all ulcers in the distal part. The location of ulcers and denuded areas differed statistically (P < 0·0001).

Conclusions  The impact of short‐term NSAID medication on the small intestine differed according to intestinal site, with most denuded areas identified in the proximal part and all ulcers in the distal part.
Does detritus quality predict the effect of native and non‐native plants on the performance of larval amphibians?
Authors: MAERZ JOHN C. , COHEN JILLIAN S. , BLOSSEY BERND
Published: April 2010

1. The lack of consistent differences between the traits of native and non‐native plant species makes it difficult to make general predictions about the ecological impact of invasive plants; however, the increasing number of non‐native plants in many habitats makes the assessment of the impact of each individual species impracticable. General knowledge about how specific plant traits are linked to their effects on communities or ecosystems may be more useful for predicting the effect of plant invasions. Specifically, we hypothesised that higher carbon‐to‐nitrogen ratio (C:N) and percent lignin in plant detritus would reduce the rate of development and total mass at metamorphosis of tadpoles, resulting in lower metamorph production (total fresh biomass) and amphibian species richness.

2. To test these hypotheses, we raised five species of tadpoles in mesocosms containing senescent leaves of three common native and three common non‐native wetland plants that varied in C:N ratio and % lignin.

3. Leaf mass loss, total metamorph production and the number of species that metamorphosed declined as a function of increasing C:N ratio of plant leaves. Plant lignin content was not related to the production of metamorphs or the number of species that metamorphosed. The percentage of wood frog (Lithobates sylvaticus) and American toad (Anaxyrus americanus) tadpoles reaching metamorphosis declined as a function of increasing plant C:N ratio. Mean time to metamorphosis increased and mean mass at metamorphosis declined as a function of increasing plant C:N ratio. Tadpole performance and metamorph diversity and production (biomass) were similar between native and non‐native plant species with similar C:N ratio in leaves. Percent lignin was not a significant predictor of tadpole performance.

4. Our results show that the impact of a plant invasion on tadpole performance could depend on differences between the quality of the detritus produced by the invading species and that of the native species it replaces. We suggest that plant community changes that lead to dominance by more recalcitrant plant species (those with higher leaf C:N ratio) may negatively affect amphibian populations.
Low crowding threshold for induction of sexual reproduction and diapause in a Patagonian rotifer
Authors: GILBERT JOHN J. , DIÉGUEZ MARÍA C.
Published: April 2010

1. This study investigates the basis and ecological significance of the extremely high propensity for mixis (sexual reproduction) observed in laboratory populations ofBrachionus calyciflorusfrom a temporary pond in Patagonia.

2. Experiments with stem females hatched from resting eggs showed that these females were exclusively amictic but produced mictic daughters even at very low population densities. In six experiments, newly hatched stem females were cultured individually in different volumes (1.5, 12, 40 and 150 mL). The percentage of mictic daughters (mixis ratio) was high in the smaller volumes (e.g. 44–83% in 1.5 mL) and lower in the largest volume (6–21% in 150 mL). A regression analysis combining the data from these experiments showed a highly significant decrease in mixis ratio with volume and indicated that the lowest population density at which mixis still occurs (mixis threshold) would be 3.4 females L−1(95% CL 2.9–4.0 females L−1). This value is considerably lower than mixis thresholds for other rotifers (25–250 females L−1for many species and 9000–477 000 females L−1for some SpanishBrachionus plicatilis).

3. In three additional experiments, stem females and their amictic daughters were cultured individually in 150 mL. The percentage of mictic daughters produced by these two generations of females was not significantly different, showing that the mixis response to crowding is not inhibited in the stem‐female generation.

4. Laboratory experiments showed that two common predators of the PatagonianB. calyciflorus(the calanoid copepodParabroteas sarsiand the backswimmerNotonecta vereertbruggheni) each ate 60–70B. calycifloruspredator−1per day and cleared all rotifers fromc.250 mL per day. Thus, a very low mixis threshold and high maximal mixis ratio may ensure production of some resting eggs soon after colonisation of the pond and before complete removal from the plankton.

5. Two laboratory experiments showed that resting eggs of the PatagonianB. calyciflorushatched at variable rates (28 and 81%) after a brief diapause when kept in the conditions under which they were produced and oviposited (20–21 °C; L: D 16: 8). Early hatching of resting eggs from pond sediment may allow multiple periods of colonisation and resting egg production in a season. This may offset the fitness cost of limited population growth through female parthenogenesis in the face of unpredictable and abrupt risk of extinction because of predators.
Riparian land use and the relationship between the benthos and litter decomposition in tropical montane streams
Authors: ENCALADA ANDREA C. , CALLES JUAN , FERREIRA VERONICA , CANHOTO CRISTINA M. , GRAÇA MANUEL A. S.
Published: April 2010

1. Although stream–catchment interactions have been analysed in some detail in temperate environments, little is known about the effects of land‐use changes in the tropics. Here, we analyse differences in benthic communities (macroinvertebrates and fungi) under two contrasting land uses (mature secondary forest and pasture) in montane streams in north‐western Ecuador and their influence on the rates of litter processing.

2. Between 2005 and 2006, we used a combination of coarse and fine mesh bags to study the relative contribution of macroinvertebrates and fungi to processing of two types of litter, Alnus acuminata and Inga spectabilis, in three‐first‐order streams running through mature secondary montane forests and adjacent downstream reaches running through pastures. At the same time, we characterised the assemblages of shreddering macroinvertebrates and fungi communities and the litter processing rates in stream reaches under both vegetation types.

3. Litter processing rates attributable to invertebrate feeding (coarse mesh bags) were significantly slower in streams running through pastures. Nevertheless, shredder diversity and richness were similar between pasture and forest sections, while shredder abundance was significantly higher in forest streams (mainly Phylloicus sp. :Trichoptera). Fungal reproductive activity and litter processing rates were low (fine mesh bags) and did not differ significantly between pasture and forest stream reaches.

4. Phylloicus sp. abundance was the best predictor of the percentage of litter remaining in coarse mesh bags across pasture and forest sites. Neither shredder diversity nor their species richness was a significant predictor of mass loss, as most of the decomposition was performed by a single keystone species. Although litter decomposition by microbial decomposers was low, fungal biomass (but not diversity) was the best variable explaining the percentage of litter remaining in fine mesh bags.

5. Our data suggest that, in these Neotropical montane streams, land use can have a significant impact on the rates of critical ecosystem processes, such as litter decomposition. In this study, this effect was not mediated by a major shift in the structure of the benthos, but by a decrease in the abundance and relative representation of a single species whose life history makes it critical to litter processing.

6. This study highlights the significant role that macroinvertebrate fauna can have in the processing of litter in Neotropical streams and the predominant role that single species can have in terms of controlling stream ecosystem‐level processes. Understanding the extent to which these patterns affect the long‐term and large‐scale functioning of stream ecosystems still needs further research and will become increasingly important in terms of managing lotic ecosystems in the context of rapid land‐use change.
Changes in fish assemblages in catchments in north‐eastern Spain: biodiversity, conservation status and introduced species
Authors: MACEDA‐VEIGA ALBERTO , MONLEON‐GETINO ANTONIO , CAIOLA NUNO , CASALS FREDERIC , De SOSTOA ADOLFO
Published: April 2010

1. North‐eastern Spain is a hot spot for the introduction of alien fish species, and its native fish fauna is one of the most endangered worldwide. We used an extensive data set from 2002 to 2003 and historical information from the area to characterize fish diversity and establish conservation priorities in river catchments.

2. Diversity indices were used to characterize fish diversity at the basin scale. An index of conservation status was applied for each species, which considers the occurrence, abundance and endemicity of each taxon. We used indirect ordination methods to test the relationship among basin features and to identify those variables most correlated with each other. To identify physical, biotic and environmental characteristics that seem to make a basin particularly susceptible to invasion, we performed a step‐wise multiple regression to examine the relationship between the number of native, translocated and introduced fish species (including the original native species richness of each basin), and landscape variables.

3. Over a period of approximately 50 years, the mean range size of native fish species has decreased by 60%. The greatest decline occurred in Gasterosteus gymnurus, Anguilla anguilla and Salaria fluviatilis, for which species over 75% of the original distribution area has been lost. The species with the highest conservation index were Gasterosteus gymnurus and Salaria fluviatilis.

4. Basin area and the catchment type explained 70% of variation in native species richness, whereas the number of dams and basin area accounted for more than 80% of variation in the number of introduced species.

5. The original native species richness and the number of introduced species at basin scale were not related, and thus there was no evidence of “biotic resistance” to invasion. The restoration of natural hydrologic processes and the development of specific management tools to protect native species, such as the prioritization of areas for fish conservation and the eradication of local populations of exotic species, are required to restore native fish fauna in these catchments.
A matter of timing: heat wave impact on crustacean zooplankton
Authors: HUBER VERONIKA , ADRIAN RITA , GERTEN DIETER
Published: April 2010

1. Climate change has affected zooplankton phenology and abundance in many freshwater ecosystems. The strong temperature anomalies that characterise summer heat waves make these events particularly suitable to study the effects of different seasonal warming patterns on zooplankton. Since heat waves are expected to occur more frequently under continuing climate change, they may also allow us to investigate how freshwater systems will be affected in the future.

2. Using a long‐term data set (1991–2007) from a shallow, eutrophic lake in Germany, we identify time periods in spring and summer during which cyclopoid copepods and bosminids are particularly sensitive to changes in water temperature. Based on this knowledge, we consider why summer populations responded differently to recent heat wave events that occurred at different times in the season.

3. Linear regressions of moving averages suggested that water temperatures shortly before and shortly after the clear‐water phase (CWP) were crucial for summer development of bosminids and cyclopoid copepods, respectively. Algal food availability (diatoms and cryptophytes) in the first weeks after the CWP also strongly influenced the summer populations of the two zooplankton groups.

4. Inter‐annual differences in water temperature during the critical time periods at least partly explained the contrasting responses of cyclopoid copepods and bosminids to heat wave events.

5. Our findings indicate that the zooplankton response to climate warming, particularly to heat wave events, is critically dependent on the temporal pattern of elevated water temperatures. Beyond that, we show that the summer zooplankton populations react to periods of warming in relation to events in the plankton annual cycle (such as the CWP in eutrophic lakes) rather than to warming at a fixed time in the season.