In this work, we experimentally study the effects of the nitrogen concentration in laser wakefield acceleration of electrons in a gas mixture of hydrogen and nitrogen. A 15 TW peak power laser pulse is focused to ionize the gas, excite a plasma wave and accelerate electrons up to 230 MeV. We find that at dopant concentrations above 2% the total divergence of the electrons is increased and the high

A newly developed pulsed cavity ring-down spectroscopy (CRDS) system for measuring atmospheric gaseous elemental mercury (GEM) concentrations at high temporal resolution (25 Hz) was used to successfully conduct the first eddy covariance (EC) flux measurements of GEM. GEM is the main gaseous atmospheric form, and quantification of bidirectional exchange between the Earth’s surface and the atmospher

The spatial and spectral filtering characteristics of a microphone array can be greatly enhanced through the use of an appropriately designed spatial/spectral filter. In this paper, we consider the design of optimum, in the minimax sense, spatial/spectral filters. The optimum minimax design problem is solved using the new efficient computational technique of Jiang et al. Numerical results demonstr

Climate change and variability are likely to increase in most parts of the world, leading to more extreme events, which may increase the stress on already threatened water resources. This study focuses on the effects of the El Niño Southern Oscillation in the rainfall of Pucara basin and in the groundwater levels of the Punata alluvial fan in the Bolivian sub-Andes. Climate change and variability

The diatom Chaetoceros calcitrans is a major component of many bivalve hatcheries, yet it is expensive and notoriously difficult to culture on a commercial scale. In an attempt to reduce dependence on the diatom C. calcitrans, mussel larvae (Mytilus galloprovincialis) were subjected to feeding experiments which altered levels of the diatom under controlled hatchery conditions. Growth, survival and

In species with complex life cycles, laboratory studies have shown that variations in the traits of settling larvae can affect post-settlement survival and influence recruitment and benthic- pelagic coupling. However, we still know little about the magnitude and spatial scale of natural trait variation. We studied spatial variation in body size and nutritional reserves (carbon, nitrogen and lipids

A major allochthon of the Scandinavian Caledonides, the Seve belt has traditionally been considered to be derived from the rifted margin and continent-ocean transition (COT) of Baltica. However, geochronological results obtained from its inferred northern equivalent, the Kalak Nappe Complex (KNC), have been taken to indicate an exotic affinity of this complex and of also Seve terranes, an interpre

Antineutrophil cytoplasmic autoantibody- (ANCA-) associated vasculitis (AAV) are relapsing-remitting disorders with unpredictable prognosis. There is a need of biomarkers for distinguishing which patients will have a more severe outcome and also for predicting relapses in disease activity. This study confirms the previous results of urinary MCP-1 (uMCP-1) as a prognostic marker and explores its po

in Ramsey’s Ontology, a special issue of Metaphysica, No. 3, 2005.

The decomposition of large stocks of soil organic carbon in thawing permafrost might depend on more than climate change-induced temperature increases: indirect effects of thawing via altered bacterial community structure (BCS) or rooting patterns are largely unexplored. We used a 10-year in situ permafrost thaw experiment and aerobic incubations to investigate alterations in BCS and potential resp

Background: A common complaint by people with tinnitus is that they experience that the tinnitus causes attention and concentration problems. Previous studies have examined how tinnitus influences cognitive performance on short and intensive cognitive tasks but without proper control of hearing status. Purpose: To examine the impact tinnitus and high-frequency hearing thresholds have on reading co

Detta är den femte skriften i den serie småskrifter som alla handlar om vetenskap och beprövad erfarenhet. Författarna är forskare och/eller politiker med stor erfarenhet av området, några är forskare inom vårt forskningsprogram Vetenskap och beprövad erfarenhet, ett sexårigt program finansierat av Riksbankens jubileumsfond.

Flux footprint models are often used for interpretation of flux tower measurements, to estimate position and size of surface source areas, and the relative contribution of passive scalar sources to measured fluxes. Accurate knowledge of footprints is of crucial importance for any upscaling exercises from single site flux measurements to local or regional scale. Hence, footprint models are ultimate