Imaging and mapping the impact of clouds on skyglow with all-sky photometry

Artificial skyglow is constantly growing on a global scale, with potential ecological consequences ranging up to affecting biodiversity. To understand these consequences, worldwide mapping of skyglow for all weather conditions is urgently required. In particular, the amplification of skyglow by clouds needs to be studied, as clouds can extend the reach of skyglow into remote areas not affected by light pollution on clear nights. Here we use commercial digital single lens reflex cameras with fisheye lenses for all-sky photometry. We track the reach of skyglow from a peri-urban into a remote area on a clear and a partly cloudy night by performing transects from the Spanish town of Balaguer towards Montsec Astronomical Park. From one single all-sky image, we extract zenith luminance, horizontal and scalar illuminance. While zenith luminance reaches near-natural levels at 5km distance from the town on the clear night, similar levels are only reached at 27km on the partly cloudy night. Our results show the dramatic increase of the reach of skyglow even for moderate cloud coverage at this site. The powerful and easy-to-use method promises to be widely applicable for studies of ecological light pollution on a global scale also by non-specialists in photometry.Comment: 13 pages, 7 figure

Omineca Herald, July, 10, 1914

Patients admitted to an intensive care unit after cardiac arrest often suffer from severe brain injury. This injury worsens further after restoration of circulation due to the cascade of reactions in the brain. Neuroprotective therapies aim to diminish this secondary brain injury, thereby targeting at a better outcome. Several new large international studies will start soon, next to two smaller national phase II studies. In this paper we describe the new studies and invite Dutch intensive care units to join

Dimensies van groei in de veehouderij = Dimensions of growth in livestock production

De Provincie Noord-Holland zet in de ontwerp-Structuurvisie (Noord-Holland 2009) in op behoud van een vitale en duurzame agrarische sector, inclusief veehouderij. Deze structuurvisie geeft in specifieke gebieden ook ruimte voor ‘schaalvergroting, structuurverbetering en (mondiaal) concurrerende landbouw’, met minder landschappelijke beperkingen. Grootschalige intensieve (hokgebonden) veehouderij krijgt een specifieke plek in de Wieringermeer. Daarmee sluit de provincie onder meer aan op de dominante trend van schaalvergroting in de landbouw in de afgelopen decennia, die zich afspeelt in alle takken van landbouw (akkerbouw, bollenteelt, grondgebonden en niet-grondgebonden veehouderij) en die volgens velen nog niet ten einde is. Deze notitie is geschreven in opdracht van de Provincie Noord-Holland ten behoeve van de discussie in de Provinciale Staten over de ontwerp-Structuurvisie. Het primaire doel is begripsvorming. De notitie zet de verschillende (economische en niet-economische) achtergronden van schaalvergroting en efficiencyverbetering uiteen, en gaat in op een reeks van maatschappelijke voor- en nadelen van deze trend, zoals concurrentiekracht, dierenwelzijn, diergezondheid en volksgezondhei

On the Exchange of Kinetic and Magnetic Energy Between Clouds and the Interstellar Medium

We investigate, through 2D MHD numerical simulations, the interaction of a uniform magnetic field oblique to a moving interstellar cloud. In particular we explore the transformation of cloud kinetic energy into magnetic energy as a result of field line stretching. Some previous simulations have emphasized the possible dynamical importance of a ``magnetic shield'' formed around clouds when the magnetic field is perpendicular to the cloud motion (Jones et al. 1996, Miniati et al. 1998). It was not clear, however, how dependent those findings were to the assumed field configuration and cloud properties. To expand our understanding of this effect, we examine several new cases by varing the magnetic field orientation angle with respect to the cloud motion (\theta), the cloud-background density contrast, and the cloud Mach number. We show that in 2D and with \theta large enough, the magnetic field tension can become dominant in the dynamics of the motion of high density contrast, low Mach number clouds. In such cases a significant fraction of cloud kinetic energy can be transformed into magnetic energy with the magnetic pressure at the cloud nose exceeding the ram pressure of the impinging flow. We derive a characteristic timescale for this process of energy ``conversion''. We find also that unless the cloud motion is highly aligned to the magnetic field, reconnection through tearing mode instabilities in the cloud wake limit the formation of a strong flux rope feature following the cloud. Finally we attempt to interpret some observational properties of the magnetic field in view of our results.Comment: 24 pages in aaspp4 Latex and 7 figures. Accepted for publication in The Astrophysical Journa

Isotopic Production Cross Sections in Proton-Nucleus Collisions at 200 MeV

Intermediate mass fragments (IMF) from the interaction of $^{27}$Al, $^{59}$Co and $^{197}$Au with 200 MeV protons were measured in an angular range from 20 degree to 120 degree in the laboratory system. The fragments, ranging from isotopes of helium up to isotopes of carbon, were isotopically resolved. Double differential cross sections, energy differential cross sections and total cross sections were extracted.Comment: accepted by Phys. Rev.