48 research outputs found
Ecosystem engineering by seagrasses interacts with grazing to shape an intertidal landscape
Self-facilitation through ecosystem engineering (i.e., organism modification of the abiotic environment) and consumer-resource interactions are both major determinants of spatial patchiness in ecosystems. However, interactive effects of these two mechanisms on spatial complexity have not been extensively studied. We investigated the mechanisms underlying a spatial mosaic of low-tide exposed hummocks and waterlogged hollows on an intertidal mudflat in the Wadden Sea dominated by the seagrass Zostera noltii. A combination of field measurements, an experiment and a spatially explicit model indicated that the mosaic resulted from localized sediment accretion by seagrass followed by selective waterfowl grazing. Hollows were bare in winter, but were rapidly colonized by seagrass during the growth season. Colonized hollows were heavily grazed by brent geese and widgeon in autumn, converting these patches to a bare state again and disrupting sediment accretion by seagrass. In contrast, hummocks were covered by seagrass throughout the year and were rarely grazed, most likely because the waterfowl were not able to employ their preferred but water requiring feeding strategy ('dabbling') here. Our study exemplifies that interactions between ecosystem engineering by a foundation species (seagrass) and consumption (waterfowl grazing) can increase spatial complexity at the landscape leve
Foundation species enhance food web complexity through non-trophic facilitation
Food webs are an integral part of every ecosystem on the planet, yet understanding the mechanisms shaping these complex networks remains a major challenge. Recently, several studies suggested that non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structure. However, it remains unclear whether these findings generalize across ecosystems, and whether non-trophic interactions affect food webs randomly, or affect specific trophic levels or functional groups. Here, we combine analyses of 58 food webs from seven terrestrial, freshwater and coastal systems to test (1) the general hypothesis that non-trophic facilitation by habitat-forming foundation species enhances food web complexity, and (2) whether these enhancements have either random or targeted effects on particular trophic levels, functional groups, and linkages throughout the food web. Our empirical results demonstrate that foundation species consistently enhance food web complexity in all seven ecosystems. Further analyses reveal that 15 out of 19 food web properties can be well-approximated by assuming that foundation species randomly facilitate species throughout the trophic network. However, basal species are less strongly, and carnivores are more strongly facilitated in foundation species' food webs than predicted based on random facilitation, resulting in a higher mean trophic level and a longer average chain length. Overall, we conclude that foundation species strongly enhance food web complexity through non-trophic facilitation of species across the entire trophic network. We therefore suggest that the structure and stability of food webs often depends critically on non-trophic facilitation by foundation species
Imatinib in patients with severe COVID-19: a randomised, double-blind, placebo-controlled, clinical trial
Background The major complication of COVID-19 is hypoxaemic respiratory failure from capillary leak and alveolar oedema. Experimental and early clinical data suggest that the tyrosine-kinase inhibitor imatinib reverses pulmonary capillary leak.Methods This randomised, double-blind, placebo-controlled, clinical trial was done at 13 academic and non-academic teaching hospitals in the Netherlands. Hospitalised patients (aged >= 18 years) with COVID-19, as confirmed by an RT-PCR test for SARS-CoV-2, requiring supplemental oxygen to maintain a peripheral oxygen saturation of greater than 94% were eligible. Patients were excluded if they had severe pre-existing pulmonary disease, had pre-existing heart failure, had undergone active treatment of a haematological or non-haematological malignancy in the previous 12 months, had cytopenia, or were receiving concomitant treatment with medication known to strongly interact with imatinib. Patients were randomly assigned (1:1) to receive either oral imatinib, given as a loading dose of 800 mg on day 0 followed by 400 mg daily on days 1-9, or placebo. Randomisation was done with a computer-based clinical data management platform with variable block sizes (containing two, four, or six patients), stratified by study site. The primary outcome was time to discontinuation of mechanical ventilation and supplemental oxygen for more than 48 consecutive hours, while being alive during a 28-day period. Secondary outcomes included safety, mortality at 28 days, and the need for invasive mechanical ventilation. All efficacy and safety analyses were done in all randomised patients who had received at least one dose of study medication (modified intention-to-treat population). This study is registered with the EU Clinical Trials Register (EudraCT 2020-001236-10).Findings Between March 31, 2020, and Jan 4, 2021, 805 patients were screened, of whom 400 were eligible and randomly assigned to the imatinib group (n=204) or the placebo group (n=196). A total of 385 (96%) patients (median age 64 years [IQR 56-73]) received at least one dose of study medication and were included in the modified intention-to-treat population. Time to discontinuation of ventilation and supplemental oxygen for more than 48 h was not significantly different between the two groups (unadjusted hazard ratio [HR] 0.95 [95% CI 0.76-1.20]). At day 28, 15 (8%) of 197 patients had died in the imatinib group compared with 27 (14%) of 188 patients in the placebo group (unadjusted HR 0.51 [0.27-0.95]). After adjusting for baseline imbalances between the two groups (sex, obesity, diabetes, and cardiovascular disease) the HR for mortality was 0.52 (95% CI 0.26-1.05). The HR for mechanical ventilation in the imatinib group compared with the placebo group was 1.07 (0.63-1.80; p=0.81). The median duration of invasive mechanical ventilation was 7 days (IQR 3-13) in the imatinib group compared with 12 days (6-20) in the placebo group (p=0.0080). 91 (46%) of 197 patients in the imatinib group and 82 (44%) of 188 patients in the placebo group had at least one grade 3 or higher adverse event. The safety evaluation revealed no imatinib-associated adverse events.Interpretation The study failed to meet its primary outcome, as imatinib did not reduce the time to discontinuation of ventilation and supplemental oxygen for more than 48 consecutive hours in patients with COVID-19 requiring supplemental oxygen. The observed effects on survival (although attenuated after adjustment for baseline imbalances) and duration of mechanical ventilation suggest that imatinib might confer clinical benefit in hospitalised patients with COVID-19, but further studies are required to validate these findings. Copyright (C) 2021 Elsevier Ltd. All rights reserved.Pathogenesis and treatment of chronic pulmonary disease
Genome-enabled insights into the biology of thrips as crop pests
Background The western flower thrips,Frankliniella occidentalis(Pergande), is a globally invasive pest and plant virus vector on a wide array of food, fiber, and ornamental crops. The underlying genetic mechanisms of the processes governing thrips pest and vector biology, feeding behaviors, ecology, and insecticide resistance are largely unknown. To address this gap, we present theF. occidentalisdraft genome assembly and official gene set.Results We report on the first genome sequence for any member of the insect order Thysanoptera. Benchmarking Universal Single-Copy Ortholog (BUSCO) assessments of the genome assembly (size = 415.8 Mb, scaffold N50 = 948.9 kb) revealed a relatively complete and well-annotated assembly in comparison to other insect genomes. The genome is unusually GC-rich (50%) compared to other insect genomes to date. The official gene set (OGS v1.0) contains 16,859 genes, of which similar to 10% were manually verified and corrected by our consortium. We focused on manual annotation, phylogenetic, and expression evidence analyses for gene sets centered on primary themes in the life histories and activities of plant-colonizing insects. Highlights include the following: (1) divergent clades and large expansions in genes associated with environmental sensing (chemosensory receptors) and detoxification (CYP4, CYP6, and CCE enzymes) of substances encountered in agricultural environments; (2) a comprehensive set of salivary gland genes supported by enriched expression; (3) apparent absence of members of the IMD innate immune defense pathway; and (4) developmental- and sex-specific expression analyses of genes associated with progression from larvae to adulthood through neometaboly, a distinct form of maturation differing from either incomplete or complete metamorphosis in the Insecta.Conclusions Analysis of theF. occidentalisgenome offers insights into the polyphagous behavior of this insect pest that finds, colonizes, and survives on a widely diverse array of plants. The genomic resources presented here enable a more complete analysis of insect evolution and biology, providing a missing taxon for contemporary insect genomics-based analyses. Our study also offers a genomic benchmark for molecular and evolutionary investigations of other Thysanoptera species.Animal science
Flat oysters in the Eierlandse Gat, Wadden Sea : Results of a survey in 2017
This report presents the results of a short survey of flat oysters (Ostrea edulis) in the Western Wadden Sea. Ten sites were visited and flat oysters were found on nine locations in the Eijerlandse gat. Empty cockleshells and live and dead Pacific oysters provided the main settlement substrate. The presence of larvae was detected in water samples by microscopic inspection and DNA analysis at several locations in the Eijerlandse gat. The results show that flat oysters have returned to the Wadden Sea after its extinction in the last century, but still occurs at low densities
Eindrapportage archeologisch onderzoek Park Berkhof en Whemerbeek, Gemeente Winterswijk
Econsultancy bv adviseert om een inventariserend veldonderzoek uit te voeren door middel van een verkennend, geo-archeologisch booronderzoek, teneinde de op basis van het bureauonderzoek opgestelde gespecificeerde archeologische verwachting van het plangebied aan te vullen en te toetsen en daarnaast een betrouwbaar beeld van de gaafheid van de bodem en de opbouw van het beekdal te verkrijgen. Geo-archeologisch booronderzoek kan tevens nader inzicht verschaffen over de aard van dieper gelegen sedimenten en de mogelijke aanwezigheid van een afgedekt archeologisch bodemarchief
Eindrapportage archeologisch onderzoek Park Berkhof en Whemerbeek, Gemeente Winterswijk
Econsultancy bv adviseert om een inventariserend veldonderzoek uit te voeren door middel van een verkennend, geo-archeologisch booronderzoek, teneinde de op basis van het bureauonderzoek opgestelde gespecificeerde archeologische verwachting van het plangebied aan te vullen en te toetsen en daarnaast een betrouwbaar beeld van de gaafheid van de bodem en de opbouw van het beekdal te verkrijgen. Geo-archeologisch booronderzoek kan tevens nader inzicht verschaffen over de aard van dieper gelegen sedimenten en de mogelijke aanwezigheid van een afgedekt archeologisch bodemarchief
Flat oysters in the Eierlandse Gat, Wadden Sea : Results of a survey in 2017
This report presents the results of a short survey of flat oysters (Ostrea edulis) in the Western Wadden Sea. Ten sites were visited and flat oysters were found on nine locations in the Eijerlandse gat. Empty cockleshells and live and dead Pacific oysters provided the main settlement substrate. The presence of larvae was detected in water samples by microscopic inspection and DNA analysis at several locations in the Eijerlandse gat. The results show that flat oysters have returned to the Wadden Sea after its extinction in the last century, but still occurs at low densities
Correlates of exercise compliance in physical therapy.
BACKGROUND AND PURPOSE: This correlational study describes factors that are related to patient compliance with exercise regimens during physical therapy. We investigated whether patient compliance was related to characteristics of the patient or the patient's illness, to the patient's attitude, or to the physical therapist's behavior. SUBJECTS AND METHODS: Of a random sample of 300 physical therapists in private practice in the Netherlands, 222 therapists responded to a questionnaire survey. Eighty-four respondents also made audio recordings. Materials of the study were 1,931 registration forms, 1,837 audio-recorded sessions of physical therapy sessions, and 1,681 patient questionnaires. RESULTS: The results show that the three main factors related to noncompliance were (1) the barriers patients perceive and encounter, (2) the lack of positive feedback, and (3) the degree of helplessness. The first factor, the barriers patients perceive and encounter, shows the strongest relation with noncompliance. The results also show that noncompliance is more strongly related to the characteristics of the illness than to the illness, a bad prognosis is negatively related to compliance, and much hindrance of the complaint is positively related to compliance. There was no difference between men and women with regard to patient compliance, but less educated patients were slightly more compliant than more highly educated patients. CONCLUSION AND DISCUSSION: These correlational findings can be used to formulate hypotheses of cause and effect in future clinical research. Future research should take into account the type and efficacy of therapeutic exercise for different diseases. For physical therapy practice, it seems important that physical therapists carefully explore which problems patients encounter in their efforts to comply and that they seek solutions to those problems in mutual cooperation with their patients. (aut. ref.
Differences between physical therapists in attention paid to patient education.
This article describes differences between physical therapists in terms of the attention they pay to educating patients. The differences between therapists were identified from audiotaped treatment sessions of 1837 patients, recorded by physical therapists in non-institutional care in the Netherlands. Trained judges assessed the quantity and the quality of the education by means of a checklist. Therapists' opinions about patient education and their work setting were also examined as possible factors associated with between-therapist diffences. The results showed that the therapists differed in their opinions about patient compliance, the number of exercise instructions given to their patients, the amount of stress-related counselling and the attention given to patients' demands and perceptions. Those therapists with high expectations about the effects of education compliance paid more attention to the education of their patients. The results also indicated that therapists who spent more time with their patients had a better relationship with them. (aut.ref.