717 research outputs found
Upscaling methane emissions from rice paddies: problems and possibilities.
No full textGlobal methane emission estimates depend highly on the models, techniques, and databases used. Since emissions cannot be measured directly at large scales, it is impossible to judge which estimate is more realistic. In this paper, different aspects of uncertainty in upscaling methane emissions from rice paddies are discussed. These aspects are visualized by a case study on the spatial upscaling of methane emissions from the island of Java, Indonesia. The first aspect concerns process information. An approach to incorporate this information in a simplified but process-based way in predictive models is discussed. Sources of uncertainty include the methane emissions measurements, processes quantification, process simplification, and the use of data transfer functions. Data availability of input parameters, the second aspect, is uncertain because of differences between different data sources, the use of data sources for purposes not originally planned for, and the scale at which data are available. Data interpolation in combination with nonlinear model responses introduces scaling errors, the third aspect. Data accuracy introduced the highest uncertainties in emission estimates but is rarely accounted for in the estimation of global emissions
Changes in the structure of the 1:2 complex of N-ethyl-N-methylmorpholinium and 7,7,8,8-tetracyano-p-quinodimethane, MEM(TCNQ)2, above room temperature: I. Determination of the structures at 294 and 323 K
No full textCrystals of MEM(TCNQ) 2 are triclinic, space group P1, with a = 7.773 (8), b = 15.292(15), c = 6.960 (7)A, a = 112.34 (6), fl = 74.59 (6), y = 111.85 (6) °, U = 702 A 3 at 294 K, and a = 7.775 (8), b= 15.290 (15), c = 6.979 (7)A, a = 112.01 (6),fl= 75.00 (6),)'= 111.77 (6) ° , U= 707 A 3 at 323 K, Z= 1. Intensities were collected with Zr-filtered Mo radiation on an automatic Nonius CAD-3 diffractometer. Anisotropic least-squares refinements decreased Rw(F) to 0.077 for 2471 reflections at 294 K, and to 0.089 for 1877 reflections at 323 K. The reported structures are compared with the structure at 113 K [Bosch & van Bodegom (1977). Acta Cryst. B33, 3013-3021]. The individual TCNQ group, as well as the types of overlap between successive TCNQ molecules in the dimerized TCNQ stack, hardly changes between l l3 and 323 K; both separationsbetween the TCNQ units increase by 0.07 A. The major change is the increasing disorder of the MEM group with increasing temperature. With the assumption of two preferred orientations the 100% occupancy of the orientation observed at 113 K decreases to 84% at 294 K and 63% at 323 K. This increase in disorder is used to explain the results of electrical-conductivity measurements
Supplemental Material - Practice of Supporting Family Caregivers of Patients with Life-Threatening Diseases: A Two-phase Study Among Healthcare Professionals
No full textSupplemental Material for Practice of Supporting Family Caregivers of Patients with Life-Threatening Diseases: A Two-phase Study Among Healthcare Professionals by Hinke E. Hoffstädt, MSc, Jannie A. Boogaard, PhD, Marcella C. Tam, MSc, Leti van Bodegom-Vos, PhD, Arianne Stoppelenburg, PhD, Iris D. Hartog, PhD, Yvette M. van der Linden, MD, PhD, and Jenny T. van der Steen, PhD, FGSA in American Journal of Hospice and Palliative Medicine®</p
Understanding the impact of main cell wall polysaccharides on the decomposition of ectomycorrhizal fungal necromass
No full textThe extramatrical mycelium of ectomycorrhizal fungi (EMF) is an important source of soil carbon and nitrogen. While the importance of recalcitrant compounds in the fungal cell wall has been explored earlier, the contribution of highly abundant but labile components, like glucans, and the role of their temporal dynamics during decomposition remains unknown. For the first time, we examined how the concentration of three main fungal cell wall components (chitin, melanin, glucans) in EMF necromass are related to necromass decomposition, over a period of 6 weeks. Although the initial concentrations of the three components were not good predictors of necromass loss, we found species-specific trends of chitin and glucans loss over time. The chitin concentration during decomposition was tightly linked to the weekly necromass degradation, with trends of chitin loss being dissimilar across fungal species. Chitin concentration was positively correlated with the mass loss in the first week, but in the remaining 5 weeks, it was found to be weakly negatively correlated with mass loss. The similarity in susceptibility to the decomposition of glucans and chitin likely compensates for the impacts of interspecific differences in their initial concentration, leading to overall similar decomposition patterns. Alternatively, other, non-measured, components (e.g., glycoproteins, N content) may contribute to explaining similar decomposition patterns. Our results indicate that ectomycorrhizal necromass decomposition processes differ from those of plant litter decomposition with, unlike in plants, differences in initial concentrations of major structural carbohydrates (e.g., glucans) being unrelated to differences in decomposition rates. These findings indicate that the decomposition of fungal material cannot be inferred from assumptions based on data provided by studies of plant decomposition.The Netherlands Organization for Scientific research, Grant/Award Number: 016.161.31
Exploration of new steerable mechanism for stiff handheld minimally invasive surgery instrument
No full textBackground: Minimally Invasive Surgery (MIS) gained increasing support in the surgical community over the last decades. Due to the rigid tip of current used rigid instruments the maneuverability is limited during a procedure. To increase maneuverability steerable instruments have been developed. However current handheld steerable instruments contain low bending stiffness, which is one of the reasons that these instruments are hardly used in clinical practice. This study aims to design and evaluate a new stiff steerable mechanism with 2 Degrees Of Freedom (DOF) for use in a handheld MIS instrument. Methods: Characteristics of the steering mechanisms were described and analyzed. The most suited approach for creating a stiff steerable mechanism was selected. Multiple 2 DOF stiff concepts were designed. Of these, three concept prototypes (scaled 10) were engineered and manufactured (3D printing). The ability to steer and the stiffness of the prototypes was evaluated. In addition, the most promising mechanism was redesigned to fit the required 5 dimensions. It’s robustness was verified using Finite Element Method (FEM) techniques. Results: Eight different mechanisms were described and analyzed. The most suited approach is a mechanism that consists of solid rods and universal joints to guide steering forces from handle to tip and external forces from tip to handle. Five concepts were designed that enable a parallel motion of which three were developed further in 10 scale prototypes. Preliminary results showed an increase in stiffness of a factor 2,7 compared to existing instruments. The real scale implementation study resulted in a 5 version of the mechanism that is capable of guiding the forces required to drive all the functionalities of a MIS instrument (steering, grasping). Conclusion: It can be concluded that a 5 steerable MIS instrument with a stiff tip is feasible. The mechanism contains a cardan mechanism and axially moving rods that slide over a special constructed surface. The scaled prototype provided at least 2,7 times higher stiffness compared to existing instruments.Mechanical, Maritime and Materials EngineeringBiomechanical Engineerin
Spectral calibration of the fluorescence telescopes of the Pierre Auger Observatory
No full textAbstract not availableA. Aab … J.A. Bellido … S.G. Blaess … R.W. Clay … M.J. Cooper … B.R. Dawson … T.D. Grubb … T.A. Harrison … G.C. Hill … P.H. Nguyen … S.J. Saffi … T. Sudholz … P. van Bodegom … [et al.] (The Pierre Auger Collaboratio
N deposition and elevated CO2 on methane emissions: Differential responses of indirect effects compared to direct effects through litter chemistry feedbacks.
No full textIncreases in atmospheric CO2 concentration and N deposition are expected to affect methane (CH4) production in soils and emission to the atmosphere, directly through increased plant litter production and indirectly through changes in substrate quality. We examined how CH4 emission responded to changes in litter quality under increased N and CO2, beyond differences in CH4 resulting from changes in litter production. We used senesced leaves from 13C-labeled plants of Molinia caerulea grown at elevated and ambient CO2 and affected by N fertilization to carry out two experiments: a laboratory litter incubation and a pot experiment. N fertilization increased N and decreased C concentrations in litter whereas elevated CO2 decreased litter quality as reflected in litter C and N concentrations and in the composition of lignin and saturated fatty acids within the litter. In contrast to our expectations, CH4 production in the laboratory incubation decreased when using litter from N-fertilized plants as substrate, whereas litter from elevated CO2 had no effect, compared to controls without N and at ambient CO2. Owing to high within-treatment variability in CH4 emissions, none of the treatment effects were reflected in the pot experiment. C mineralization rates were not affected by any of the treatments. The decrease in CH4 emissions due to indirect effects of N availability through litter quality changes (described here for the first time) contrast direct effects of N fertilization on CH4 production. The complex interaction of direct effects with indirect effects of increased N on litter quality may potentially result in a net decrease in CH4 emissions from wetlands in the long term.Fil: Pancotto, Veronica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Bodegom, P. M. van. University Of Amsterdam; Países BajosFil: Hal, J. van. University Of Amsterdam; Países BajosFil: Logtestijn, R. S. P. van. University Of Amsterdam; Países BajosFil: Blokker, P.. University Of Amsterdam; Países BajosFil: Toet, S.. University Of Amsterdam; Países Bajos. University Of York; Reino UnidoFil: Aerts, R.. University Of Amsterdam; Países Bajo
Genetic variation in pentraxin (PTX) 3 gene associates with PTX3 production and fertility in women
No full textPentraxin 3 (PTX3) plays an important role in innate immune responses and in female fertility, as discovered with studies in mice. However, the role of PTX3 in human fertility is unknown. Here, we report on a population-based study from a rural area of Upper East Ghana (n = 4346). We studied the association between the number of children given birth by women during their lifetime and ex vivo, lipopolysaccharide (LPS)-induced PTX3 production (n = 362). In addition, we studied the association of genetic variation in the PTX3 gene with PTX3 production (n = 617) and with female fertility (n = 1999). We found that ex vivo LPS-induced PTX3 production was associated with fertility (P = 0.040). Furthermore, we identified genetic variants in the PTX3 gene that influence PTX3 production, and also fertility. The strongest associations were observed for the rs6788044 single-nucleotide polymorphism (SNP). We found that carriers of this SNP had higher PTX3 production capacity (P = 0.003) and higher fertility (P = 0.043). The results reported here provide the first evidence, based on protein production and analysis of polymorphisms, that the long pentraxin PTX3 plays a role in female fertility in humans
Fungal communities are passengers in community development of dune ecosystems, while bacteria are not
No full textAn increasing number of studies of above-belowground interactions provide a fundamental basis for our understanding of the coexistence between plant and soil communities. However, we lack empirical evidence to understand the directionality of drivers of plant and soil communities under natural conditions: 'Are soil microorganisms driving plant community functioning or do they adapt to the plant community?' In a field experiment in an early successional dune ecosystem, we manipulated soil communities by adding living (i.e., natural microbial communities) and sterile soil inocula, originating from natural ecosystems, and examined the annual responses of soil and plant communities. The experimental manipulations had a persistent effect on the soil microbial community with divergent impacts for living and sterile soil inocula. The plant community was also affected by soil inoculation, but there was no difference between the impacts of living and sterile inocula. We also observed an increasing convergence of plant and soil microbial composition over time. Our results show that alterations in soil abiotic and biotic conditions have long-term effects on the composition of both plant and soil microbial communities. Importantly, our study provides direct evidence that soil microorganisms are not "drivers" of plant community dynamics. We found that soil fungi and bacteria manifest different community assemblies in response to treatments. Soil fungi act as "passengers," that is, soil microorganisms reflect plant community dynamics but do not alter it, whereas soil bacteria are neither "drivers" nor "passengers" of plant community dynamics in early successional ecosystems. These results are critical for understanding the community assembly of plant and soil microbial communities under natural conditions and are directly relevant for ecosystem management and restoration.Environmental BiologyPlant science
Soil biota adversely affect the resistance and recovery of plant communities subjected to drought
No full textPlant science
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