Paleomagnetism and astronomically induced cyclicity of the Armantes section; a Miocene continental red sequence in the Calatayud-Daroca basin (Central Sapin)

The Armantes section is a red-bed sequence consisting of a regular altemation (10 m scale) of reddish silts and pink/white limestones.In between these limestones, a smaller-scale bedding (2-3 m scale) is intercalated, characterised by varying carbonate content and related differences in erosion resistance. An earlier correlation of the magnetic polarity sequence of the Armantes section to the geomagnetic polarity time scale (GPTS) suggested a periodicity of 111 kyr for the large-scale cyclicity (Krijgsman et al., 1994b). The carbonate, gamma-ray and susceptibility records indicate that 4 to 5 small-scale cycles are developed in one large-scale cycle, showing that the small-scale cyclicity is related to precession and thus caused by climate forcing. We suggest that the precipitation of the carbonates is most likely related to rising ground-water levels and an increase of evaporation. This implies that the thick limestone beds would correlate to eccentricity maxima and the smaller-scale limestone beds to precession minima. Rock magnetic experiments show that the NRM in the Armantes section results from the presence of hematite and magnetite/maghemite.The relative contribution of hematite is strongly related to the lithology. Hematite is the dominant carrier in the limestones, while in the silts magnetite/maghemite prevail

The Zuurland-2 Borehole: some remarks on the results of the geological and paleontological investigations

Wetensch. publicatieFaculty of Archeolog

Palaeoflow and Sediment Delivery Reconstructions from Martian Delta Morphology by Combined Modelling and HRSC DTM Analysis

have been formed by sapping. On the left of the delta there is a second lobe that may have formed as an initial drowned delta or alluvial fan. Summary: The size and shape of alluvial fans and deltas contain information on their formative time scale, sediment supply and the amount of water involved. A new numerical morphological model is presented that allows quantitative comparison of morphological predictions and HRSC DTMdata of six deltas. As morphology is uniquely coupled to water and sediment flux, the model also discriminates between dense flows (slurries) and dilute flows (rivers). We demonstrate that two Gilbert (Fig. 1) and three stepped fan deltas may have formed by dilute flows into filling lakes in less than 10 years. Introduction: Alluvial fans and deltas on Mars record past hydrological conditions. Until now these conditions were inferre

Source population synthesis and the Galactic diffuse gamma-ray emission

Population synthesis is used to study the contribution from undetected sources to the Galactic ridge emission measured by EGRET. Synthesized source counts are compared with the 3rd EGRET catalogue at low and high latitudes. For pulsar-like populations, 5-10% of the emission >100 MeV comes from sources below the EGRET threshold. A steeper luminosity function can increase this to 20% without violating EGRET source statistics. Less luminous populations can produce much higher values without being detected. Since the unresolved source spectrum is different from the interstellar spectrum, it could provide an explanation of the observed MeV and GeV excesses above the predictions, and we give an explicit example of how this could work.Comment: Astrophysics and Space Science, in press. (Proceedings of Conference 'The multi-messenger approach to high-energy gamma-ray sources', Barcelona, 2006). Minor changes for accepted version, updated reference

The mid-Cretaceous North Atlantic nutrient trap: Black shales and OAEs

Organic-rich sediments are the salient marine sedimentation product in the mid-Cretaceous of the ocean basins formed in the Mesozoic. Oceanic anoxic events (OAEs) are discrete and particularly organic-rich intervals within these mid-Cretaceous organic-rich sequences and are defined by pronounced carbon isotope excursions. Marine productivity during OAEs appears to have been enhanced by the increased availability of biolimiting nutrients in seawater due to hydrothermal alteration of submarine basalts in the Pacific and proto-Indian oceans. The exact mechanisms behind the deposition of organic-rich sediments in the mid-Cretaceous are still a matter of discussion, but a hypothesis which is often put forward is that their deposition was a consequence of the coupling of a particular paleogeography with changes in ocean circulation and nutrient supply. In this study, we used a global coupled climate model to investigate oceanic processes that affect the interbasinal exchange of nutrients as well as their spatial distribution and bioavailability. We conclude that the mid-Cretaceous North Atlantic was a nutrient trap as a consequence of an estuarine circulation with respect to the Pacific. Organic-rich sediments in the North Atlantic were deposited below regions of intense upwelling. We suggest that enhanced productivity during OAEs was a consequence of upwelling of Pacific-derived nutrient-rich seawater associated with submarine igneous events

Development and validation of a patient- tailored dose regime in myocardial perfusion imaging using conventional SPECT

Background\ud The decreasing image quality in heavier patients can be compensated by administration of a patient-specific dose in myocardial perfusion imaging (MPI) using a cadmium zinc telluride-based SPECT camera. Our aim was to determine if the same can be achieved when using a conventional SPECT camera.\ud \ud \ud Methods\ud 148 patients underwent SPECT stress MPI using a fixed Tc-99m tetrofosmin tracer dose. Measured photon counts were normalized to administered tracer dose and scan time and were correlated with body weight, body mass index, and mass per length to find the best predicting parameter. From these data, a protocol to provide constant image quality was derived, and subsequently validated in 125 new patients.\ud \ud \ud Results\ud Body weight was found to be the best predicting parameter for image quality and was used to derive a new dose formula; Aadmin (MBq) = 223·body weight (kg)0.65/Tscan (min). The measured photon counts decreased in heavier patients when using a fixed dose (P < .01) but this was no longer observed after applying a body-weight-dependent protocol (P = .20).\ud \ud \ud Conclusions\ud Application of a patient-specific protocol resulted in an image quality less depending on patient’s weight. The results are most likely independent of the type of SPECT camera used, and, hence, adoption of patient-specific dose and scan time protocols is recommended

A new interpretation of the Escucha and Utrillas Fm in their reference sections: sedimentology and evolution of a sandy desert system (erg) in the eastern margin of Iberia

Nuevos datos obtenidos en el periodo 2004-2008, indican que las areniscas y arcillas de parte de la “clásica Fm. Escucha” y de la “clásica Fm. Utrillas” constituyen un sistema desértico arenoso (erg) en el que se desarrollaron dunas eólicas crescénticas, interdunas, dunas complejas, draas lineares, sabkhat detríticas, playa lakes y lags de deflación con ventifactos, bajo condiciones climáticas áridas. Este erg presenta un límite proximal (orla de wadis) con el Macizo Ibérico y un límite distal con el Tethys (marine erg-margin system). El cambio climático acaecido en Iberia en el tránsito Aptiense-Albiense, hacia condiciones climáticas áridas, favoreció el desarrollo del sistema desértico arenoso. El descubrimiento del primer sistema desértico cretácico de Europa abre nuevas vías para la comprensión de los procesos paleoclimáticos y paleoceanográficos acaecidos durante el Cretácico Medio.New data obtained in the 2004-2008 period, show that sandstones and mudstones of part of “the classic Escucha Fm.” and of “the classic Utrillas Fm.” constitute a sandy desert system (erg) in which crescentic aeolian dunes, interdunes, complex dunes, linear draas, detrital sabkhat, playa lakes and deflation lags with ventifacts developed under arid climate conditions. This erg system displays a proximal boundary with the Iberian Massif (wadi belt) and a distal boundary with the Tethys (marine erg-margin system). The climate change in Iberia in the transit between Aptian-Albian towards arid climate conditions allowed the development of the sandy desert system. The discovery of the first Cretaceous erg reported from Europe opens new insights for understanding both palaeoclimate and palaeogeography during Mid-CretaceousDepto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Levels and trends in cardiovascular risk factors and drug treatment in 4837 elderly Dutch myocardial infarction patients between 2002 and 2006

Contains fulltext : 108511.pdf (publisher's version ) (Open Access

Perspectieven bedrijfsmaatregelen voor duurzaambodemgebruik : kosten en effectiviteit van vijf maatregelen

In dit onderzoek zijn de kosten en baten en de effectiviteit op duurzaam bodemgebruik beoordeeld van vijf bedrijfsmaatregelen: aanpassing van vruchtwisseling, preventie van bodemverdichting, optimalisering van ontwatering en flexibel peilbeheer, grondruil en landhuur/-verhuur en omzanden en diepploegen. De effecten op duurzaam bodemgebruik zijn beoordeeld op de aspecten organische stof, bodemstructuur, erosiegevoeligheid en bodemgezondheid. Verruiming van vruchtwisseling met meer maaivruchten en minder rooivruchten gaat meestal ten koste van het bedrijfsinkomen. Bij vruchtwisseling is bodemgezondheid een belangrijk aspect. Bodemverdichting kan worden verminderd. Dit vraagt meestal flinke investeringen. Met een goed management en goede voorlichting kan nog veel worden bereikt. Veranderingen in water- en peilbeheer gaan deels vaak ten koste van een optimale landbouwkundige productie. Er kunnen echter ook maatregelen worden toegepast die niet of nauwelijks nadelig zijn vanuit landbouwkundig oogpunt, maar wel gunstig zijn voor natuur en maatschappi