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

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

Precision Photometry for Q0957+561 Images A and B

Since the persuasive determination of the time-delay in Q0957+561, much interest has centered around shifting and subtracting the A and B light-curves to look for residuals due to microlensing. Solar mass objects in the lens galaxy produce variations on timescales of decades, with amplitudes of a few tenths of a magnitude, but MACHO's (with masses of order $10^{-3}$ to $10^{-7}M_\odot$) produce variations at only the 5% level. To detect such small variations, highly precise photometry is required. To that end, we have used 200 observations over three nights to examine the effects of seeing on the light-curves. We have determined that seeing itself can be responsible for correlated 5% variations in the light-curves of A and B. We have found, however, that these effects can be accurately removed, by subtracting the light from the lens galaxy, and by correcting for cross contamination of light between the closely juxtaposed A and B images. We find that these corrections improve the variations due to seeing from 5% to a level only marginally detectable over photon shot noise (0.5%).Comment: 21 Pages with 9 PostScript figures, AASTeX 4 (preprint style

Chin-spot as an indicator of age in pond bats

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

Predation of wood mice (Apodemus sylvaticus) on hibernating bats

Contains fulltext : 163408.pdf (publisher's version ) (Open Access

De ontwikkeling van een meetinstrument:de pelletkachel in Boerakker

Dit rapport beschrijft de ontwikkeling van een enquête. De enquête moet de interesse naar het gebruik van pelletkachels meten. De interesse wordt gemeten in de kleine dorpen in Noord-Nederland. Daarnaast is een informatieve flyer ontworpen die bij de enquête bijgevoegd wordt om de respondenten informatie te geven over de pelletkachel. Het doel van het onderzoek: De ontwikkeling van een bruikbare enquête om de interesse inpelletkachels te meten. Probleemstelling: Onduidelijkheid over het draagvlak voor de pelletkachels in kleine dorpen in Noord-Nederland. Er is in een eerdere fase van het onderzoek een interview gehouden met initiatiefgroepen uit Boerakker. De output van het interview, waarin veel informatie is vergaard, is gebruikt voor de input van de enquête. De aanbevelingen die worden gedaan zijn als volgt te formuleren: Voordat de enquête uitgezet wordt, moeten de respondenten op de hoogte worden gebracht door middel van een mailing. Hierbij krijgen de enquêteerden informatie over de datum wanneer ze de enquête kunnen verwachten. Daarnaast wordt er op geattendeerd dat er bij het afnemen van de enquête eerst de inhoudelijke vragen worden gesteld om vervolgd te worden door de persoonsgegevens. Hierdoor wordt de nadruk gelegd op de inhoud, wat relevant is voor het vervolg van het onderzoek voor het Kenniscentrum Gebiedsontwikkeling NoorderRuimte. Studentenonderzoek in het kader van het thema Duurzaam bouwen

Non-annular, hemispheric signature of the winter North Atlantic Oscillation

Sensitivity experiments with an atmospheric general circulation model (AGCM) without a proper stratosphere are performed to locally force a North Atlantic oscillation (NAO)-like response in order to analyse the tropospheric dynamics involved in its hemispheric extent. Results show that the circulation anomalies are not confined to the North Atlantic basin not even within the first 10 days of integration, where the atmospheric response propagates downstream into the westerly jets. At this linear stage, transient-eddy activity dominates the emerging, regional NAO- like pattern while zonal-eddy coupling may add on top of the wave energy propagation. Later at the quasi-equilibrium nonlinear stage, the atmospheric response emphasizes a wavenumber-5 structure embedded in the westerly jets, associated with transient-eddy feedback upon the Atlantic and Pacific storm-tracks. This AGCM waveguided structure rightly projects on the observational NAO-related circumglobal pattern, providing evidence of its non-annular character in the troposphere. These findings support the view on the importance of the circumglobal waveguide pattern on the development of NAO-related anomalies at hemispheric level. It could help to settle a consensus view of the Arctic Oscillation, which has been elusive so far.This work has been partially supported by the CANON Foundation in Europe (Grant 2011-062). JG-S was partially supported by the H2020-funded MSCA-IF-EF DPETNA project (GA No. 655339). Thanks to Mashiro Watanabe and Masato Mori (AORI, University of Tokyo) for useful discussions in the early stages of this study. Thanks also to Francisco J. Doblas-Reyes (BSC, Spain) and Pablo Zurita-Gotor (UCM, Spain) for their help during the review process. Technical support at BSC (Computational Earth Sciences group) is sincerely acknowledged. The authors are grateful to the anonymous reviewers for their encouragement and helpful suggestions.Peer ReviewedPostprint (author's final draft

Turbulence in Galaxy Cluster Cores: a Key to Cluster Bimodality?

We study the effects of externally imposed turbulence on the thermal properties of galaxy cluster cores, using three-dimensional numerical simulations including magnetic fields, anisotropic thermal conduction, and radiative cooling. The imposed "stirring" crudely approximates the effects of galactic wakes, waves generated by galaxies moving through the intracluster medium (ICM), and/or turbulence produced by a central active galactic nucleus. The simulated clusters exhibit a strong bimodality. Modest levels of turbulence, ~100 km/s (~10% of the sound speed), suppress the heat-flux-driven buoyancy instability (HBI), resulting in an isotropically tangled magnetic field and a quasi-stable, high entropy, thermal equilibrium with no cooling catastrophe. Thermal conduction dominates the heating of the cluster core, but turbulent mixing is critical because it suppresses the HBI and (to a lesser extent) the thermal instability. Lower levels of turbulent mixing (approximately less than 100 km/s) are insufficient to suppress the HBI, rapidly leading to a thermal runaway and a cool-core cluster. Remarkably, then, small fluctuations in the level of turbulence in galaxy cluster cores can initiate transitions between cool-core (low entropy) and non cool-core (high entropy) states.Comment: Published in ApJ Letter

Assessing 20th century climate-vegetation feedbacks of land-use change and natural vegetation dynamics in a fully coupled vegetation-climate model

This study describes the coupling of the dynamic global vegetation model (DGVM), Lund–Potsdam–Jena Model for managed land (LPJmL), with the general circulation model (GCM), Simplified Parameterizations primitivE Equation DYnamics model (SPEEDY), to study the feedbacks between land-use change and natural vegetation dynamics and climate during the 20th century. We show that anthropogenic land-use change had a stronger effect on climate than the natural vegetation's response to climate change (e.g. boreal greening). Changes in surface albedo are an important driver of the climate's response; but, especially in the (sub)tropics, changes in evapotranspiration and the corresponding changes in latent heat flux and cloud formation can be of equal importance in the opposite direction. Our study emphasizes that implementing dynamic vegetation into climate models is essential, especially at regional scales: the dynamic response of natural vegetation significantly alters the climate change that is driven by increased atmospheric greenhouse gas concentrations and anthropogenic land-use chang