1,446 research outputs found

    Het nemen van monsters ter bepaling van de geleidbaarheid en het chloridegehalte van de grond met behulp van poreuze potjes

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    Geleidingsvermogen van de bodem, bepaald met keramisch materiaal: "porous cup sampling

    De invloed van geinfiltreerd oppervlaktewater op het zoutgehalte van het bodemvocht in de grond en op de produktie van bolgewassen in de polder Anna Paulowna

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    In genoemde polder wordt de watervoorziening geregeld met behulp van het gemaal J.C. de Leeuw vanuit het Amstelmeer. Vanwege het veelal hoge zoutgehalte van dit boezemwater heeft het tot gevolg, dat het oppervlaktewater in de polder in ongunstige zin wordt beïnvloed. Dit kan leiden tot een vermindering van de groei en produktie van gevoelige bolgewassen. De laatste jaren is een sterk wisselend zoutgehalte van het oppervlaktewater in de polder waargenomen

    Calibrating the relation of low-frequency radio continuum to star formation rate at 1 kpc scale with LOFAR

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    9 figures, 6 tables and 17 pages. This paper is part of the LOFAR surveys data release 1 and has been accepted for publication in a special edition of A&A that will appear in Feb 2019, volume 622. The catalogues and images from the data release will be publicly available on lofar-surveys.org upon publication of the journal. Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO.Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free-free) emission. We calibrate the conversion from the spatially resolved 140 MHz RC emission to the SFR surface density (ΣSFR\Sigma_{\rm SFR}) at 1 kpc scale. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw-Frequency ARray (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio ΣSFR\Sigma_{\rm SFR} maps using the Condon relation. We compared these maps with hybrid ΣSFR\Sigma_{\rm SFR} maps from a combination of GALEX far-ultraviolet and Spitzer 24 μm\mu\rm m data using plots tracing the relation at 1.2×1.21.2\times 1.2-kpc2^2 resolution. The RC emission is smoothed with respect to the hybrid ΣSFR\Sigma_{\rm SFR} owing to the transport of cosmic-ray electrons (CREs). This results in a sublinear relation (ΣSFR)RC[(ΣSFR)hyb]a(\Sigma_{\rm SFR})_{\rm RC} \propto [(\Sigma_{\rm SFR})_{\rm hyb}]^{a}, where a=0.59±0.13a=0.59\pm 0.13 (140 MHz) and a=0.75±0.10a=0.75\pm 0.10 (1365 MHz). Both relations have a scatter of σ=0.3 dex\sigma = 0.3~\rm dex. If we restrict ourselves to areas of young CREs (α>0.65\alpha > -0.65; IνναI_\nu \propto \nu^\alpha), the relation becomes almost linear at both frequencies with a0.9a\approx 0.9 and a reduced scatter of σ=0.2 dex\sigma = 0.2~\rm dex. We then simulate the effect of CRE transport by convolving the hybrid ΣSFR\Sigma_{\rm SFR} maps with a Gaussian kernel until the RC-SFR relation is linearised; CRE transport lengths are l=1l=1-5 kpc. Solving the CRE diffusion equation, we find diffusion coefficients of D=(0.13D=(0.13-1.5)×1028cm2s11.5) \times 10^{28} \rm cm^2\,s^{-1} at 1 GeV. A RC-SFR relation at 1.41.4 GHz can be exploited to measure SFRs at redshift z10z \approx 10 using 140140 MHz observations.Peer reviewe

    Fatigue in Multiple Sclerosis Is Associated With Childhood Adversities

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    Fatigue is a common and disabling symptom in patients with Multiple Sclerosis (PwMS). Its pathogenesis, however, is still not fully understood. Potential psychological roots, in particular, have received little attention to date. The present study examined the association of childhood adversities, specific trait characteristics, and MS disease characteristics with fatigue symptoms utilizing path analysis. Five hundred and seventy-one PwMS participated in an online survey. Standardized psychometric tools were applied. The Childhood Trauma Questionnaire (CTQ) served to assess childhood adversities. Trait variables were alexithymia (Toronto Alexithymia Scale; TAS-26) and early maladaptive schemas (Young Schema Questionnaire; YSQ). Current pathology comprised depression (Beck's Depression Inventory FastScreen; BDI-FS) and anxiety symptoms (State-Trait Anxiety Inventory; STAI-state), as well as physical disability (Patient determined Disease Steps; PDDS). The Fatigue Scale for Motor and Cognitive Functions (FSMC) was the primary outcome variable measuring fatigue. PwMS displayed high levels of fatigue and depression (mean FSMC score: 72; mean BDI-II score: 18). The final path model revealed that CTQ emotional neglect and emotional abuse remained as the only significant childhood adversity variables associated with fatigue. There were differential associations for the trait variables and current pathology: TAS-26, the YSQ domain impaired autonomy and performance, as well as all current pathology measures had direct effects on fatigue symptoms, accounting for 28.2% of the FSMC variance. Bayesian estimation also revealed indirect effects from the two CTQ subscales on FSMC. The final model fitted the data well, also after a cross-validation check and after replacing the FSMC with the Chalder Fatigue Questionnaire (CFQ). This study suggests an association psychological factors on fatigue in Multiple Sclerosis. Childhood adversities, as well as specific trait characteristics, seem to be associated with current pathology and fatigue symptoms. The article discusses potential implications and limitations

    Biological outcome measurements for behavioral interventions in multiple sclerosis

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    Behavioral interventions including exercise, stress management, patient education, psychotherapy and multidisciplinary neurorehabilitation in general are receiving increasing recognition in multiple sclerosis (MS) clinical practice and research. Most scientific evaluations of these approaches have focused on psychosocial outcome measures such as quality of life, fatigue or depression. However, it is becoming increasingly clear that neuropsychiatric symptoms of MS are at least partially mediated by biological processes such as inflammation, neuroendocrine dysfunction or regional brain damage. Thus, successful treatment of these symptoms with behavioral approaches could potentially also affect the underlying biology. Rigidly designed scientific studies are needed to explore the potential of such interventions to affect MS pathology and biological pathways linked to psychological and neuropsychiatric symptoms of MS. Such studies need to carefully select outcome measures on the behavioral level that are likely to be influenced by the specific intervention strategy and should include biomarkers with evidence for an association with the outcome parameter in question. In this overview, we illustrate how biological and psychological outcome parameters can be combined to evaluate behavioral interventions. We focus on two areas of interest as potential targets for behavioral interventions: depression and fatigue

    How to measure fluctuating impairments in people with MS: development of an ambulatory assessment version of the EQ-5D-5L in an exploratory study

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    Background Health fluctuations even within a single day are typical in multiple sclerosis (MS), but are not captured by widely used questionnaires like the EQ-5D-5L. This exploratory study aimed to develop an ambulatory assessment (AA) version of the EQ-5D-5L (EQ-5D-AA) where patients rate their health on mobile phones multiple times per day over several days, and to assess its feasibility and face validity. Methods An initial EQ-5D-AA version was based on two patient focus groups. It was then tested and continuously developed in an iterative process: patients completed it over several days, followed by debriefing interviews. Findings were used to refine the EQ-5D-AA, with the resulting version being tested by the subsequent wave of patients until participants declared no need for changes anymore. Before and after the AA period, participants completed the standard paper-based EQ-5D-5L asking about ‘today’. Results Focus group participants reported that their impairments often fluctuated between and within days. They regarded an AA with three assessments per day over seven days most appropriate; assessment should be retrospective to the previous assessment, but not all items should be assessed at each time point. Four waves of AA testing were conducted. Thirteen out of the 17 participants preferred the AA over standard assessment as they regarded it more informative, but not too burdensome. Conclusion The newly developed one-week AA of the EQ-5D-5L captures within-day and day-to-day health fluctuations in people with MS. From the patients’ perspective, it is a feasible and face valid way to provide important information beyond what is captured by the standard EQ-5D-5L

    Gamma-Rays and the Far-Infrared-Radio Continuum Correlation Reveal a Powerful Galactic Centre Wind

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    We consider the thermal and non-thermal emission from the inner 200 pc of the Galaxy. The radiation from this almost star-burst-like region is ultimately driven dominantly by on-going massive star formation. We show that this region's radio continuum (RC) emission is in relative deficit with respect to the expectation afforded by the Far- infrared-Radio Continuum Correlation (FRC). Likewise we show that the region's gamma-ray emission falls short of that expected given its star formation and resultant supernova rates. These facts are compellingly explained by positing that a powerful (400-1200 km/s) wind is launched from the region. This wind probably plays a number of important roles including advecting positrons into the Galactic bulge thus explaining the observed ~kpc extension of the 511 keV positron annihilation signal around the GC. We also show that the large-scale GC magnetic field falls in the range ~100-300 microG and that - in the time they remain in the region - GC cosmic rays do not penetrate into the region's densest molecular material.Comment: Version accepted for publication in MNRAS Letters. Discussion extended and references adde
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