Experimental evaluation of elemental behavior during LA-ICP-MS: influences of plasma conditions and limits of plasma robustness

Matrix effects are one of the frequently observed and discussed issues challenging the accuracy of LA-ICP-MS results. The specific role of the ICP as a source of elemental fractionation seems not fully understood. We report the results of an experiment using six internationally available reference materials (five silicates, one carbonate) measured under 11 different plasma conditions. The thermal/energetic state of the plasma was estimated based on the ratio of Ar-38(+) and Ar-40(2)+ ions. We show that element specific behavior (volatile vs. refractory) dominates at cool but vanishes under hot plasma conditions. For robust (hot) plasma conditions matrix-tolerance seems to be achieved. Additionally we address the problem of matrix-load with respect to the plasma conditions. We've estimated practical limits for the amount of matrix which can be introduced into the ICP without significantly changing the plasma condition

Transformar políticas de informalidad urbana: el caso de la transición tunecina

Este artículo se ocupa del estudio del «sector informal» o «economía informal» en el discurso sobre desarrollo. La pregunta es: ¿hasta qué punto y por qué la estructura de la economía informal, su predominio en áreas urbanas y su vinculación con sectores marginados de la sociedad justifican la afirmación de que el levantamiento tunecino de 2010-2011 puede considerarse una «revolución informal»? Incorporando debates de la sociología y antropología urbanas, el artículo explora la relación entre la informalidad y la vida cotidiana en las ciudades, conectando el impacto de la globalización, las políticas neoliberales y la gobernanza urbana con las actividades económicas informales de los ciudadanos de áreas urbanas marginadas y segregadas espacialmente. El argumento se ilustra con un estudio de caso del levantamiento tunecino de 2010-2011 que pone de manifiesto el cambiante papel de la informalidad y su influencia sobre la gobernanza urbana de la economía informal, en particular sobre el comercio informal

New Keynesian DSGE Models and the IS-LM Paradigm

New Keynesian DSGE models propose a dynamic and expectational version of the old IS-LM paradigm. Acknowledging that the Taylor rule as a substitute for the LM-curve has its merits we show that standard DSGE models do not model how the central bank achieves its targets. In filling this gap we make evident that models neglecting a store-of-value function of money but still assuming a Taylor rule are inconsistent. Our major point concerns the-so called new Keynesian IS-curve. We prove that DSGE models which typically rest on the assumption of representative agents are unable to derive the IS-curve. This implies that these models lack the capability to analyse the role of savings as a a gap in aggregate demand. By assuming overlapping generations we make evident how this shortcoming can be avoided. We also show how OLG models add a richer dynamics to the standard DSGE approach

Simulating Visual Attention Allocation of Pilots in an Advanced Cockpit Environment

This paper describes the results of experiments conducted with human line pilots and a cognitive pilot model during interaction with a new 40 Flight Management System (FMS). The aim of these experiments was to gather human pilot behavior data in order to calibrate the behavior of the model. Human behavior is mainly triggered by visual perception. Thus, the main aspect was to setup a profile of human pilots' visual attention allocation in a cockpit environment containing the new FMS. We first performed statistical analyses of eye tracker data and then compared our results to common results of familiar analyses in standard cockpit environments. The comparison has shown a significant influence of the new system on the visual performance of human pilots. Further on, analyses of the pilot models' visual performance have been performed. A comparison to human pilots' visual performance revealed important improvement potentials

A simplified procedure for the determination of stable chlorine isotope ratios (δ37Cl) using LA-MC-ICP-MS

Stable chlorine isotopes (37Cl, 35Cl) are considered as important tracers of geochemical processes, especially in subduction zone systems. However, high-quality chlorine isotope data are scarcely available. Here we present a comparatively simple procedure for the precise and accurate determination of stable chlorine isotope ratios (δ37Cl) using LA-MC-ICP-MS. Chlorine was extracted from solid samples by pyrohydrolysis. After quantitative precipitation as AgCl the dried precipitates where analysed in a sample-standard bracketing approach using a weak laser ablation (0.3 J/cm2) for sample evaporation. Atlantic Ocean sea salt and the sea water standard IAPSO were used as SMOC (standard mean ocean chloride) for normalisation (δ37Cl = 0 ‰). The precision and accuracy of the presented method was validated analysing the reference materials JB-1a and JB-2. The chlorine isotope ratios of these standards were determined as δ37ClJB-1a = (−0.99 ± 0.06) ‰ and δ37ClJB-2 = (−0.60 ± 0.03) ‰ (errors 2SE), respectively, in accordance with published data. Applying the presented method a total amount of less than 1 μg of chlorine was consumed during a typical measurement including 10 ablation periods on the sample

Superparamagnetic iron oxide polyacrylic acid coated {\gamma}-Fe2O3 nanoparticles does not affect kidney function but causes acute effect on the cardiovascular function in healthy mice

This study describes the distribution of intravenously injected polyacrylic acid (PAA) coated {\gamma}-Fe2O3 NPs (10 mg kg-1) at the organ, cellular and subcellular levels in healthy BALB/cJ mice and in parallel addresses the effects of NP injection on kidney function, blood pressure and vascular contractility. Magnetic resonance imaging (MRI) and transmission electron microscopy (TEM) showed accumulation of NPs in the liver within 1h after intravenous infusion, accommodated by intracellular uptake in endothelial and Kupffer cells with subsequent intracellular uptake in renal cells, particularly the cytoplasm of the proximal tubule, in podocytes and mesangial cells. The renofunctional effects of NPs were evaluated by arterial acid-base status and measurements of glomerular filtration rate (GFR) after instrumentation with chronically indwelling catheters. Arterial pH was 7.46 and 7.41 in mice 0.5 h after injections of saline or NP, and did not change over the next 12h. In addition, the injections of NP did not affect arterial PCO2 or [HCO3-] either. Twenty-four and 96h after NP injections, the GFR averaged 11.0 and 13.0 ml min-1 g-1, respectively, values which were statistically comparable with controls (14.0 and 14.0 ml min-1 g-1). Mean arterial blood pressure (MAP) decreased 12-24h after NP injections (111 vs 123 min-1) associated with a decreased contractility of small mesenteric arteries revealed by myography to characterise endothelial function. In conclusion, our study demonstrates that accumulation of superparamagnetic iron oxide nanoparticles does not affect kidney function in healthy mice but temporarily decreases blood pressure.Comment: 21 pages, 12 figures, published in Toxicology and Applied Pharmacology 201