1,334 research outputs found

    Partial baldness in relation to reproduction in pond bats in the Netherlands

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    Meervleermuizen (Myotis dasycneme) vertonen vaak opvallende kale plekken op de rug. Aan de hand van data van meer dan 2200 gevangen meervleermuizen tussen 2003 en 2008 hebben we de mogelijke sociale, eologische en fysiologische oorzaken achter dit fenomeen onderzocht. De aanwezigheid van kale plekken is duidelijk gerelateerd aan de zoogperiode van vrouwtjes. We hebben onderzocht hoe recent het door ons waargenomen patroon i

    Chin-spot as an indicator of age in pond bats

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    Tijdens ecologisch veldonderzoek is het vaak nuttig om de leeftijd van een dier te kunnen bepalen. Bij de watervleermuis (Myotis daubentonii) kan de verkleuring van de kinvlek gebruikt worden om de leeftijd van het individu te bepalen. In dit artikel onderzoeken we in hoeverre de verkleuring van de kinvlek ook toepasbaar is voor leeftijdsbepaling bij meervleermuizen (Myotis dasyneme). We concluderen dat de kleur van de kinvlek een betrouwbaar kenmerk is om de leeftijd van de meervleermuis te bepale

    Soliton core filling in superfluid Fermi gases with spin-imbalance

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    In this paper the properties of dark solitons in superfluid Fermi gases with spin-imbalance are studied by means of a recently developed effective field theory [S. N. Klimin, J. Tempere, G. Lombardi, J. T. Devreese, Eur. Phys. J. B 88, 122 (2015)] suitable to describe the BEC-BCS crossover in ultracold gases in an extended range of temperatures as compared to the usual Ginzburg-Landau treatments. The spatial profiles for the total density and for the density of the excess-spin component, and the changes of their properties across the BEC-BCS crossover are examined in different conditions of temperature and imbalance. The presence of population imbalance is shown to strongly affect the structure of the soliton excitation by filling its core with unpaired atoms. This in turn influences the dynamical properties of the soliton since the additional particles in the core have to be dragged along thus altering the effective mass.Comment: 9 pages, 9 figure

    Semantic Involvement of Initial and Final Lexical Embeddings during Sense-Making: The Advantage of Starting Late

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    During spoken language interpretation, listeners rapidly relate the meaning of each individual word to what has been said before. However, spoken words often contain spurious other words, like day in daisy, or dean in sardine. Do listeners also relate the meaning of such unintended, spurious words to the prior context? We used ERPs to look for transient meaning-based N400 effects in sentences that were completely plausible at the level of words intended by the speaker, but contained an embedded word whose meaning clashed with the context. Although carrier words with an initial embedding (day in daisy) did not elicit an embedding-related N400 effect relative to matched control words without embedding, carrier words with a final embedding (dean in sardine) did elicit such an effect. Together with prior work from our lab and the results of a Shortlist B simulation, our findings suggest that listeners do semantically interpret embedded words, albeit not under all conditions. We explain the latter by assuming that the sense-making system adjusts its hypothesis for how to interpret the external input at every new syllable, in line with recent ideas of active sampling in perception

    Soil processes as a guiding principle in precision agriculture : a case study for Dutch arable farming

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    The fact that conventional agricultural practices have many detrimental effects is widely acknowledged (Rabbinge, 1997). To mitigate these effects, Dutch policy makers have implemented environmental laws that are essentially based on characteristic indicators for groundwater quality. This has resulted in progressively tighter restrictions on the input of N fertilisers and a consistent reduction of the number of registered pesticides. Enforcement of these laws still creates considerable problems, which is partly caused by their generic character: no provision is made for the significant variation among soil types. As this variation is well known to farmers, their affinity with the imposed rules and regulations is limited. This thesis follows a different approach, in which soil variability is placed at the starting point of research, using the techniques of precision agriculture. The objectives are:Develop a methodology that efficiently describes soil variability at the within-field level. Soil variability should be described in terms of functional properties that are directly relevant to farm management operations. In other words: describe soils in terms of their water regimes, nutrient cycling and sorption characteristics rather than using traditional taxonomic properties such as texture, soil organic matter (SOM) content and colour.Based on the above, develop methods to: (i) optimise the application of N fertiliser and (ii) evaluate and control the environmental risks associated with pesticide use. These methods should be developed through prototyping (Vereijcken, 1997) with ample attention for operational aspects.In line with the desired setting, research was conducted on a commercial arable farm in the central-western part of the Netherlands (51 o17'N, 4 o32'E). The farm covers an area of approximately 100 ha and applies a crop rotation of winter wheat, consumption potatoes and sugar beet. Soils originate from marine deposits, are generally calcareous and have textures ranging from sandy loam to clay. They are characterised as fine, mixed, mesic Typic Fluvaquents (Soil Survey Staff, 1998) or Mn25A-Mn45A on the Dutch 1:50,000 soil map (Vos, 1984). Soil variability is large and mainly expressed through differences in texture, soil organic matter (SOM) content and subsoil composition (peat or mineral matter). Drainage conditions are excellent and in general terms the area is considered prime agricultural land.In order to fully exploit the potential of precision agriculture, an understanding is required of the biophysical processes that govern the growth conditions of a crop. Simulation models provide a powerful tool in this respect and play a crucial role throughout this thesis. To maximize the accuracy of modelling results, much effort was invested in producing high-quality input data. Four methods were compared to derive soil hydraulic parameters from the basic soil properties collected in a 1,5000 soil survey of the study area. Applied methods included: (A) laboratory measurements, (B) class pedotransfer functions, (C) continuous pedotransfer functions and (D) continuous pedotransfer functions combined with simple laboratory measurements. Modelling performance was evaluated by comparing simulated and measured soil moisture contents for three sites and two depths. The combination of continuous pedotransfer functions and simple laboratory measurements (method D) clearly produced best results. Modelling performance was highest overall and results were consistent for individual profiles and depths. Modelling uncertainty was lowest, far lower than the uncertainty resulting from the measured data set. (Chapter 2)With the soil hydraulic parameters available, attention focused on describing soil variability. Soils were characterised in terms of simulated functional properties relating to water regimes and nutrient dynamics. Four properties were considered: water stress, N-stress, N-leaching and residual N-content at harvest. Sensitivity to water stress was evaluated for a dry year (1989); other properties were quantified for a wet year (1987). Based on functional similarity, individual soil profiles were grouped into functional classes. Standard interpolation techniques and a boundary detection algorithm subsequently identified soil functional units in each field. Analysis of variance revealed that over 65% of the spatial variation could thus be accounted for. This confirmed that soil characterisation had been efficient and that the resulting units were suitable entities to be used as management units for precision agriculture. (Chapter 3)Once the management units had been established, two field experiments were conducted to compare precision and conventional N management. The experiments were conducted in consecutive years (1998 and 1999) and on different winter wheat fields ( Triticum aestivum L.). Precision management used real-time simulations to monitor soil mineral N levels in each management unit. Early warning was provided when mineral N concentrations dropped below a critical threshold. Used as a trigger , this information served to optimise the timing of four consecutive N fertilisations. Fertiliser rates were determined through exploratory simulations, which calculated the amount of mineral N required under normal conditions. Compared to conventional management, fertiliser input was reduced by 15-27% without affecting grain yield. Grain quality was either not affected (1999) or significantly increased (1998; P Besides N fertilisation, which so far has been the major topic in precision agricultural research, pesticide management received ample attention. A step-wise evaluation was conducted to investigate the effects of soil variability and weather conditions on pesticide leaching. As a first step, a relative risk assessment identified pesticides presenting a relatively high risk to the environment. Second, the effect of weather conditions was analysed through 20 years of simulations for three distinct soil profiles. Results were summarised in cumulative probability plots to provide a probabilistic characterisation of historical weather data. The year matching 90% probability (1981) served as a reference in step three to simulate pesticide leaching from individual soil profiles. After interpolation, areas were identified where pesticide concentrations in percolating water exceeded the environmental threshold of 0.1 μg l-1. Out of a total of 19 pesticides, the risk assessment identified isoproturon, metribuzin and bentazon as relatively high-risk for leaching. Risk levels differed strongly, with isoproturon presenting the lowest risk and bentazon presenting the highest risk. Soil variability strongly affected leaching at the within-field, field and farm levels. Spatial variability was highest for isoproturon, followed by metribuzin and bentazon. Opportunities for precision management were apparent, but depended on the scale level (within-field, field or farm level) at which the environmental threshold is implemented. When legislation is formulated on this issue, the presented step-wise evaluation can serve as a basis for identification and precision management of high-risk pesticides. (Chapter 6)To synthesize the above, the various studies were discussed in terms of their implications for environmental regulations on groundwater quality. A clear distinction was made between environmental threshold concentrations (50 mg l -1for nitrate; 0.1 μg l-1for pesticides) and proxy measures that are used to enforce these thresholds. Proxy measures applied in the Netherlands include maximum N fertilisation rates and a list of registered pesticides. Simulation results indicated that these measures cannot guarantee that environmental threshold concentrations are not exceeded. Their generic character presents a problem, as different soils show quite different behaviour in terms of N and pesticide dynamics. Feasible alternatives to proxy measures are not likely to be found within the context of conventional arable farming. Precision agriculture, however, does present realistic prospects to increase control over nitrate and pesticide emissions. In future it may well be worth to stimulate the introduction of precision agriculture, especially in areas where groundwater is used as a source of drinking water. (Chapter 7

    Barriers, motivators, and facilitators of physical activity in dementia patients:A systematic review

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    Purpose: Physical activity (PA) has the potential to slow the progression of dementia patients' cognitive and physical decline. A better understanding of the factors that facilitate or hamper dementia patients' PA participation will increase the success rate of implementing PA in dementia patients' daily care. We systematically screened the barriers, motivators, and facilitators of PA participation in dementia patients, complementing previous analyses of quantitative correlates of PA in community-dwelling dementia patients. Methods: Systematic searches yielded 78 potential studies of which seven met the eligibility criteria including 39 dementia patients and 36 caregivers (33 spouses and three daughters). Results: We identified 35 barriers, 26 motivators, and 21 facilitators related to PA. We reduced these factors to six themes within the social-ecological model. Prominent barriers to PA were physical and mental limitations and difficulties with guidance and organization of PA by caregivers. Motivators included the motivation to maintain physical and mental health and participate in preferred PA options. Facilitators included strategies to avoid health problems, providing support and guidance for PA, and access to convenient and personalized PA options. Conclusions: The emerging picture suggests that dementia patients' PA participation will increase if service providers become familiar with the health benefits of PA, the characteristics of PA programs, methods of delivery, and the concepts of how such programs can be personalized to and synchronized with patients' individual needs. (C) 2016 Elsevier Ireland Ltd. All rights reserved

    Paradigm of biased PAR1 (protease-activated receptor-1) activation and inhibition in endothelial cells dissected by phosphoproteomics

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    Thrombin is the key serine protease of the coagulation cascade and mediates cellular responses by activation of PARs (protease-activated receptors). The predominant thrombin receptor is PAR1, and in endothelial cells (ECs), thrombin dynamically regulates a plethora of phosphorylation events. However, it has remained unclear whether thrombin signaling is exclusively mediated through PAR1. Furthermore, mechanistic insight into activation and inhibition of PAR1-mediated EC signaling is lacking. In addition, signaling networks of biased PAR1 activation after differential cleavage of the PAR1 N terminus have remained an unresolved issue. Here, we used a quantitative phosphoproteomics approach to show that classical and peptide activation of PAR1 induce highly similar signaling, that low thrombin concentrations initiate only limited phosphoregulation, and that the PAR1 inhibitors vorapaxar and parmodulin-2 demonstrate distinct antagonistic properties. Subsequent analysis of the thrombin-regulated phosphosites in the presence of PAR1 inhibitors revealed that biased activation of PAR1 is not solely linked to a specific G-protein downstream of PAR1. In addition, we showed that only the canonical thrombin PAR1 tethered ligand induces extensive early phosphoregulation in ECs. Our study provides detailed insight in the signaling mechanisms downstream of PAR1. Our data demonstrate that thrombin-induced EC phosphoregulation is mediated exclusively through PAR1, that thrombin and thrombin-tethered ligand peptide induce similar phosphoregulation, and that only canonical PAR1 cleavage by thrombin generates a tethered ligand that potently induces early signaling. Furthermore, platelet PAR1 inhibitors directly affect EC signaling, indicating that it will be a challenge to design a PAR1 antagonist that will target only those pathways responsible for tissue pathology

    Academic buoyancy: Overcoming test anxiety and setbacks

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    High levels of test anxiety can be damaging for academic achievement, wellbeing, and mental health. It is important, therefore, to consider those psychological attributes that may offer protection against the development of test anxiety and its negative consequences, thereby contributing to a potential positive future life trajectory. Academic buoyancy, the ability to respond effectively to academic pressures and setbacks, is one such attribute that offers protection from high test anxiety. We begin by defining test anxiety and a brief review of the literature to consider the harmful nature of test anxiety. This is followed by a definition of academic buoyancy and brief review of the literature to consider the beneficial character of academic buoyancy. Next, we describe the Self-Regulatory Executive Function model of test anxiety and consider the mechanisms and processes by which academic buoyancy exerts beneficial effects on test anxiety. The paper concludes with a consideration of critical issues for the conceptualisation and measurement of academic buoyancy, arising from the synergies, connections, and relations, theorised with test anxiety, and how these may inform future studies

    Development and process evaluation of a motor activity program for people with profound intellectual and multiple disabilities

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    Background The support of people with profound intellectual and multiple disabilities (PIMD) rarely focused on motor activity, which might have negative consequences for the quality of life of these people. Evidence-based motor activity programs that present individually tailored and structural motor activity for these people are, regretfully, lacking. This study developed such a program for these people and evaluated the implementation process. Methods The motor activity program is developed in accordance with the theoretical premises of the educational program and consists of four methodological steps in which the content is individually filled with: motor activity structurally embedded within the activities of daily living, and 3–5 motor activities aimed at a specific goal, which is evaluated. Program delivery consisted of a manual, explanation to the teams, and coaching of one contact person per participant (n = 9). Process evaluation included the delivered fidelity, dose, reach, and adaptations made during the program. In addition, mechanisms of impact and the influence of contextual factors were evaluated. Data collection included researcher logbooks, individual program content, and staff reports. Results The intended fidelity, dose, and reach were not obtained in most participants. Content has been made explicit for seven participants, but only in one participant all critical steps in implementation were performed as intended, though later in time. In three participants, previously offered motor activities were described within the weekly program, but without all activities having a clear link with the goal set. It is showed that the core elements of the program were affected with the conceived implementation plan. The time schedule, critical elements in implementation and program content were influenced by a lack of conditions such as professionals’ motivation and responsibility, methodical working, interdisciplinarity and continuity in staff. Conclusions The results suggest that the implementation might be improved in case more attention is paid to the organizational conditions and implementation structure. The findings led to substantial changes in the implementation strategy. This study underlines the importance of process evaluation prior to testing for effectiveness

    The dynamic characteristics of the mouse horizontal vestibulo-ocular and optokinetic response

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    In the present study the optokinetic reflex, vestibulo-ocular reflex and their interaction were investigated in the mouse, using a modified subconjunctival search coil technique. Gain of the ocular response to sinusoidal optokinetic stimulation was relatively constant for peak velocities lower than 8°/s, ranging from 0.7 to 0.8. Gain decreased proportionally to velocity for faster stimuli. The vestibulo-ocular reflex acted to produce a sinusoidal compensatory eye movement in response to sinusoidal stimuli. The phase of the eye movement with respect to head movement advanced as stimulus frequency decreased, the familiar signature of the torsion pendulum behavior of the semicircular canals. The first-order time constant of the vestibulo-ocular reflex, as measured from the eye velocity decay after a vestibular velocity step, was 660 ms. The response of the vestibulo-ocular reflex changed with stimulus amplitude, having a higher gain and smaller phase lead when stimulus amplitude was increased. As a result of this nonlinear behavior, reflex gain correlated strongly with stimulus acceleration over the 0.1-1.6 Hz frequency range. When whole body rotation was performed in the light the optokinetic and vestibular system combined to generate nearly constant response gain (approximately 0.8) and phase (approximately 0°) over the tested frequency range of 0.1-1.6 Hz. We conclude that the compensatory eye movements of the mouse are similar to those found in other afoveate mammals, but there are also significant differences, namely shorter apparent time constants of the angular VOR and stronger nonlinearities
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