2,144 research outputs found

    A new wireless underground network system for continuous monitoring of soil water contents

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    A new stand-alone wireless embedded network system has been developed recently for continuous monitoring of soil water contents at multiple depths. This paper presents information on the technical aspects of the system, including the applied sensor technology, the wireless communication protocols, the gateway station for data collection, and data transfer to an end user Web page for disseminating results to targeted audiences. Results from the first test of the network system are presented and discussed, including lessons learned so far and actions to be undertaken in the near future to improve and enhance the operability of this innovative measurement approac

    Progress of the National Air Quality Cooperation Programme (NSL)

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    Om de luchtkwaliteit in Nederland te verbeteren is het Nationaal Samenwerkingsprogramma Luchtkwaliteit (NSL) opgezet. In dit programma werken de Rijksoverheid en decentrale overheden samen om te zorgen dat Nederland overal tijdig aan de grenswaarden voor fijnstof (2011) en stikstofdioxide (2015) zal voldoen. Om de voortgang te volgen is bij het NSL een monitoringsprogramma opgezet. Centraal onderdeel daarvan is een rekeninstrument waarvoor de overheden de brongegevens aanleveren. De daaruitvolgende rekenresultaten zijn vervolgens door het Bureau Monitoring (samenwerkingsverband RIVM en InfoMil) samengevoegd in voorliggende voortgangsrapportage. De prognoses voor 2011 en 2015 laten zien dat voor een groot deel van Nederland de resultaten onder de Europese grenswaarden voor PM10 (fijnstof) en NO2 liggen. Op een aantal plekken zijn er wel nieuwe of grotere overschrijdingen van de PM10- en NO2-grenswaarden zichtbaar. Bij de fijnstof (PM10) overschrijdingen gaat het hoofdzakelijk om locaties bij veehouderijen en een aantal industriele gebieden. Vooral nabij veehouderijen is op een aantal plekken nog sprake van grote overschrijdingen die lastig voor medio 2011 op te lossen zijn. De huidige prognose voor de concentraties stikstofdioxide in 2015 laat een minder gunstige ontwikkeling zien ten opzichte van wat is berekend in de vaststelling van het NSL. Dit komt voor een belangrijk deel door tegenvallende verkeersemissies wat heeft geleid tot een aantal nieuwe overschrijdingen. De nu in de prognoses berekende concentraties liggen op veel locaties net onder de grenswaarde. Met veel concentraties net onder de grenswaarde neemt het aantal overschrijdingen snel toe bij een tegenvaller in een van de gemaakte aannamen. In combinatie met een grote en deels onbekende onzekerheid in de rekenresultaten vormt dit een risico voor het behalen van de doelstelling van het NSL.The NSL has been put in place to improve air quality in the Netherlands and to ensure that the Netherlands meets the date of compliance with the EU limit values for particulate matter and nitrogen dioxide. Local, regional and national authorities work together within the framework of this programme to ensure that these goals are met. A monitoring programme, centred around a specially designed assessment tool, has been set up to monitor the progress. This tool uses data that the participating authorities are required to provide as part of the annual monitoring cycle. The results of the tool have been bundled by the Bureau Monitoring into this progress report. The prognosis for 2011 and 2015, based on the results obtained using the assessment tool, are that the concentrations of PM10 and NO2 fall below the EU limit values in most parts of the Netherlands. However, exceedances of the limit values do occur at specific locations. For PM10, these exceedances mostly occur close to a number of industrial sites and stock farms. Particularly high exceedances in the vicinity of these stock farms will make it difficult to meet the limit values by mid 2011 at these locations. The prognostications for NO2 show a less favourable decline in NO2 concentrations than was modelled at the establishment of the NSL. This is mostly due to the decline in traffic emissions falling short of expectations, resulting in new exceedances. At many locations, the calculated concentrations in the prognostications fall just under the limit value and, consequently, there will be a large increase in the number of exceedances when one or more of the premises become less favourable. This possibility, together with the large and partially unknown uncertainty in the calculation results, add up to a risk for not meeting the limit values by the date of compliance.VRO

    Integrative proteomic analysis of the NMDA NR1 knockdown mouse model reveals effects on central and peripheral pathways associated with schizophrenia and autism spectrum disorders

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    Background: Over the last decade, the transgenic N-methyl-D-aspartate receptor (NMDAR) NR1-knockdown mouse (NR1neo-/-) has been investigated as a glutamate hypofunction model for schizophrenia. Recent research has now revealed that the model also recapitulates cognitive and negative symptoms in the continuum of other psychiatric diseases, particularly autism spectrum disorders (ASD). As previous studies have mostly focussed on behavioural readouts, a molecular characterisation of this model will help to identify novel biomarkers or potential drug targets. Methods. Here, we have used multiplex immunoassay analyses to investigate peripheral analyte alterations in serum of NR1neo-/- mice, as well as a combination of shotgun label-free liquid chromatography mass spectrometry, bioinformatic pathway analyses, and a shotgun-based 40-plex selected reaction monitoring (SRM) assay to investigate altered molecular pathways in the frontal cortex and hippocampus. All findings were cross compared to identify translatable findings between the brain and periphery. Results: Multiplex immunoassay profiling led to identification of 29 analytes that were significantly altered in sera of NR1neo-/- mice. The highest magnitude changes were found for neurotrophic factors (VEGFA, EGF, IGF-1), apolipoprotein A1, and fibrinogen. We also found decreased levels of several chemokines. Following this, LC-MS E profiling led to identification of 48 significantly changed proteins in the frontal cortex and 41 in the hippocampus. In particular, MARCS, the mitochondrial pyruvate kinase, and CamKII-alpha were affected. Based on the combination of protein set enrichment and bioinformatic pathway analysis, we designed orthogonal SRM-assays which validated the abnormalities of proteins involved in synaptic long-term potentiation, myelination, and the ERK-signalling pathway in both brain regions. In contrast, increased levels of proteins involved in neurotransmitter metabolism and release were found only in the frontal cortex and abnormalities of proteins involved in the purinergic system were found exclusively in the hippocampus. Conclusions: Taken together, this multi-platform profiling study has identified peripheral changes which are potentially linked to central alterations in synaptic plasticity and neuronal function associated with NMDAR-NR1 hypofunction. Therefore, the reported proteomic changes may be useful as translational biomarkers in human and rodent model drug discovery efforts

    Alternative reproductive tactics, sperm mobility and oxidative stress in Carollia perspicillata (Seba's short-tailed bat)

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    In social systems with alternative reproductive tactics, sneakers face a higher level of sperm competition than harem males and hence are predicted to allocate more resources to ejaculates. Antioxidants can protect sperm against oxidative stress, and thus, their allocation to the ejaculate may depend on mating tactic. In this study on the frugivorous bat Carollia perspicillata, we assessed, for harem and sneaker males, four spermmobility traits, blood and ejaculatemarkers of the redox balance and the ejaculate to blood ratios of the redox markers. Under higher sperm competition, sneaker males should allocate proportionally more antioxidant resources to the protection of sperm than harem males. In contrast, harem males should favour pre-copulatory functions, which comprise the protection of blood. We found significantly higher sperm velocity and sperm survival in sneakers. There was no correlation between spermmobility and spermenzymatic antioxidant activity or ejaculate levels of lipid peroxidation (oxidative damage). Ejaculate levels of lipid peroxidation and sperm survival showed a significantly positive correlation, which could be attributed to the role of reactive oxygen species for sperm capacitation. Harem and sneaker males showed similar levels of redox balance markers in ejaculate and blood. However, harem males showed a higher ratio of oxidized over reduced glutathione in blood, which may indicate higher cellular stress due to higher metabolism. Overall, our findings suggest that sneakers of C. perspicillata compensate for a higher level of sperm competition by higher sperm mobility. Significance statement In social systems with alternative reproductive tactics, sneakers face higher level of sperm competition than harem males and hence are predicted to allocate more resources to ejaculates. Antioxidants can protect sperm against oxidative stress, and thus, their allocation to the ejaculate may depend on mating tactic. In this study on the frugivorous bat Carollia perspicillata, we found sperm swimming significantly faster and longer in sneaker males compared to harem males. However, traits other than the investigated antioxidant may favour higher sperm mobility. Measured redox pattern in blood of harem males may indicate higher cellular stress due to higher metabolism. Our results provide support to the current sperm competition models at the intraspecific level, which is still debated for internal fertilizers. This study contributes to better understanding the trade-offs and adaptations resulting from alternative reproductive tactics in mammals

    Nuclear structure studies with the 7Li(e,e'p) reaction

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    Experimental momentum distributions for the transitions to the ground state and first excited state of 6He have been measured via the reaction 7Li(e,e'p)6He, in the missing momentum range from -70 to 260 MeV/c. They are compared to theoretical distributions calculated with mean-field wave functions and with variational Monte Carlo (VMC) wave functions which include strong state-dependent correlations in both 7Li and 6He. These VMC calculations provide a parameter-free prediction of the momentum distribution that reproduces the measured data, including its normalization. The deduced summed spectroscopic factor for the two transitions is 0.58 +/- 0.05, in perfect agreement with the VMC value of 0.60. This is the first successful comparison of experiment and ab initio theory for spectroscopic factors in p-shell nuclei.Comment: 4 pages, 3 figure

    Jastrow-type calculations of one-nucleon removal reactions on open ss-dd shell nuclei

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    Single-particle overlap functions and spectroscopic factors are calculated on the basis of Jastrow-type one-body density matrices of open-shell nuclei constructed by using a factor cluster expansion. The calculations use the relationship between the overlap functions corresponding to bound states of the (A1)(A-1)-particle system and the one-body density matrix for the ground state of the AA-particle system. In this work we extend our previous analyses of reactions on closed-shell nuclei by using the resulting overlap functions for the description of the cross sections of (p,d)(p,d) reactions on the open ss-dd shell nuclei 24^{24}Mg, 28^{28}Si and 32^{32}S and of 32^{32}S(e,ep)(e,e^{\prime}p) reaction. The relative role of both shell structure and short-range correlations incorporated in the correlation approach on the spectroscopic factors and the reaction cross sections is pointed out.Comment: 11 pages, 5 figures, to be published in Phys. Rev.

    Inferring the time-dependent complex Ginzburg-Landau equation from modulus data

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    We present a formalism for inferring the equation of evolution of a complex wave field that is known to obey an otherwise unspecified (2+1)-dimensional time-dependent complex Ginzburg-Landau equation, given field moduli over three closely-spaced planes. The phase of the complex wave field is retrieved via a non-interferometric method, and all terms in the equation of evolution are determined using only the magnitude of the complex wave field. The formalism is tested using simulated data for a generalized nonlinear system with a single-component complex wave field. The method can be generalized to multi-component complex fields.Comment: 9 pages, 9 figure

    Eccentricity Growth Rates of Tidally Distorted Discs

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    We consider discs that orbit a central object and are tidally perturbed by a circular orbit companion. Such discs are sometimes subject to an eccentric instability due to the effects of certain resonances. Eccentric instabilities may be present in planetary rings perturbed by satellites, protostellar discs perturbed by planets, and discs in binary star systems. Although the basic mechanism for eccentric instability is well understood, the detailed response of a gaseous disc to such an instability is not understood. We apply a linear eccentricity evolution equation developed by Goodchild and Ogilvie. We explore how the eccentricity is distributed in such a disc and how the distribution in turn affects the instability growth rate for a range of disc properties. We identify a disc mode, termed the superhump mode, that is likely at work in the superhump binary star case. The mode results from the excitation of the fundamental free precession mode. We determine an analytic expression for the fundamental free mode precession rate that is applicable to a sufficiently cool disc. Depending on the disc sound speed and disc edge location, other eccentric modes can grow faster than the superhump mode and dominate.Comment: 11 pages, 15 figures to be published on MNRA

    Spontaneous Branching of Anode-Directed Streamers between Planar Electrodes

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    Non-ionized media subject to strong fields can become locally ionized by penetration of finger-shaped streamers. We study negative streamers between planar electrodes in a simple deterministic continuum approximation. We observe that for sufficiently large fields, the streamer tip can split. This happens close to Firsov's limit of `ideal conductivity'. Qualitatively the tip splitting is due to a Laplacian instability quite like in viscous fingering. For future quantitative analytical progress, our stability analysis of planar fronts identifies the screening length as a regularization mechanism.Comment: 4 pages, 6 figures, submitted to PRL on Nov. 16, 2001, revised version of March 10, 200

    2s1/2 occupancies in 30Si, 31P, and 32S

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    Elastic electron scattering off Si-30 and P-31 was studied in an effective momentum-transfer range of 1.8-3.0 fm(-1). The form-factor data were analyzed together with existing data sets for these nuclei and for S-32 in a model-independent Fourier-Bessel expansion. For P-31 the M1 contribution was subtracted following an established parametrization. Results of Hartree-Fock (HF) calculations, performed for these three nuclei in a spherical basis and in an axially deformed basis, are compared to experiment. Occupancies have been determined which, when used in the spherical-basis HF calculations, lead to a good description of the elastic form-factor data. The deformed-basis calculations have been used to study the influence of the deformation on the calculated binding energies and ground-state charge densities. In all calculations the influence of using different effective nucleon-nucleon interactions was investigated. The resulting differences in 2s(1/2) in occupancy are combined with results from previous existing (e,e'p) experiments to yield ''absolute occupancies'' for the 2s(1/2) orbital. The deduced 2s(1/2) occupancies for Si-30 and S-32 are 0.24(4) and 1.35(19), respectively.Peer reviewe
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