1,462 research outputs found
A spatially explicit and quantitative vulnerability assessment of ecosystem service change in Europe
Environmental change alters ecosystem functioning and may put the provision of services to human at risk. This paper presents a spatially explicit and quantitative assessment of the corresponding vulnerability for Europe, using a new framework designed to answer multidisciplinary policy relevant questions about the vulnerability of the human-environment system to global change. Scenarios were constructed for a range of possible changes in socio-economic trends, land uses and climate. These scenarios were used as inputs in a range of ecosystem models in order to assess the response of ecosystem function as well as the changes in the services they provide. The framework was used to relate the impacts of changing ecosystem service provision for four sectors in relation to each other, and to combine them with a simple, but generic index for societal adaptive capacity. By allowing analysis of different sectors, regions and development pathways, the vulnerability assessment provides a basis for discussion between stakeholders and policymakers about sustainable management of EuropeÂżs natural resource
On Retardation Effects in Space Charge Calculations Of High Current Electron Beams
Laser-plasma accelerators are expected to deliver electron bunches with high
space charge fields. Several recent publications have addressed the impact of
space charge effects on such bunches after the extraction into vacuum.
Artifacts due to the approximation of retardation effects are addressed, which
are typically either neglected or approximated. We discuss a much more
appropriate calculation for the case of laser wakefield acceleration with
negligible retardation artifacts due to the calculation performed in the mean
rest frame. This presented calculation approach also aims at a validation of
other simulation approaches
Effect of Supplementing Grass Silage with Incremental Levels of Water Soluble Carbohydrate on in Vitro Rumen Microbial Growth and N Use Efficiency
The efficiency of utilisation of N for milk production in dairy cows is often less than 25% and a shortfall in readily available carbohydrate to provide substrate for microbial growth is often cited as a potential problem. Grasses bred for their high water soluble carbohydrate (WSC) content have potential to address this issue but there is limited information on the level of sugar required to optimise rumen microbial growth efficiency. The objective of this experiment was to examine the effect of different concentrations of WSC on the efficiency of use of grass silage N under in vitro conditions
Helium-3 and Helium-4 acceleration by high power laser pulses for hadron therapy
The laser driven acceleration of ions is considered a promising candidate for
an ion source for hadron therapy of oncological diseases. Though proton and
carbon ion sources are conventionally used for therapy, other light ions can
also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the
same penetration depth as 250 MeV protons, helium ions require only 250 MeV per
nucleon, which is the lowest energy per nucleon among the light ions. This fact
along with the larger biological damage to cancer cells achieved by helium
ions, than that by protons, makes this species an interesting candidate for the
laser driven ion source. Two mechanisms (Magnetic Vortex Acceleration and
hole-boring Radiation Pressure Acceleration) of PW-class laser driven ion
acceleration from liquid and gaseous helium targets are studied with the goal
of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy
requirements. We show that He3 ions, having almost the same penetration depth
as He4 with the same energy per nucleon, require less laser power to be
accelerated to the required energy for the hadron therapy.Comment: 8 pages, 3 figures, 1 tabl
Absolute calibration of GafChromic film for very high flux laser driven ion beams.
We report on the calibration of GafChromic HD-v2 radiochromic film in the extremely high dose regime up to 100 kGy together with very high dose rates up to 7 Ă— 1011 Gy/s. The absolute calibration was done with nanosecond ion bunches at the Neutralized Drift Compression Experiment II particle accelerator at Lawrence Berkeley National Laboratory (LBNL) and covers a broad dose dynamic range over three orders of magnitude. We then applied the resulting calibration curve to calibrate a laser driven ion experiment performed on the BELLA petawatt laser facility at LBNL. Here, we reconstructed the spatial and energy resolved distributions of the laser-accelerated proton beams. The resulting proton distribution is in fair agreement with the spectrum that was measured with a Thomson spectrometer in combination with a microchannel plate detector
The Effect of Dry Matter Content and Inoculation with Lactic Acid Bacteria on the Residual Water Soluble Carbohydrate Content of Silages Prepared from a High Sugar Grass Cultivar
The introduction of new perennial ryegrass cultivars bred for high water soluble carbohydrate (WSC) content has created opportunities for improving the quality of grass silage, by not only providing adequate WSC for a good fermentation, but also sufficient to leave a higher residual level of WSC in the mature silage. High WSC silages have the potential to provide readily available energy during the early stages of rumen fermentation to balance energy and nitrogen supply and optimise rumen microbial growth. (Merry et al. 2002). The aim was to examine the effect of wilting and silage inoculants on the residual WSC content of grass silage
Effects of Hyperbolic Rotation in Minkowski Space on the Modeling of Plasma Accelerators in a Lorentz Boosted Frame
Laser driven plasma accelerators promise much shorter particle accelerators
but their development requires detailed simulations that challenge or exceed
current capabilities. We report the first direct simulations of stages up to 1
TeV from simulations using a Lorentz boosted calculation frame resulting in a
million times speedup, thanks to a frame boost as high as gamma=1300. Effects
of the hyperbolic rotation in Minkowski space resulting from the frame boost on
the laser propagation in the plasma is shown to be key in the mitigation of a
numerical instability that was limiting previous attempts
A recursive paradigm for aligning observed behavior of large structured process models
The alignment of observed and modeled behavior is a crucial problem in process mining, since it opens the door for conformance checking and enhancement of process models. The state of the art techniques for the computation of alignments rely on a full exploration of the combination of the model state space and the observed behavior (an event log), which hampers their applicability for large instances. This paper presents a fresh view to the alignment problem: the computation of alignments is casted as the resolution of Integer Linear Programming models, where the user can decide the granularity of the alignment steps. Moreover, a novel recursive strategy is used to split
the problem into small pieces, exponentially reducing the complexity of the ILP models to be solved. The contributions of this paper represent a promising alternative to fight the inherent complexity of computing alignments for large instances.Peer ReviewedPostprint (author's final draft
Defining the fine structure of promoter activity on a genome-wide scale with CISSECTOR
Classic promoter mutagenesis strategies can be used to study how proximal promoter regions regulate the expression of particular genes of interest. This is a laborious process, in which the smallest sub-region of the promoter still capable of recapitulating expression in an ectopic setting is first identified, followed by targeted mutation of putative transcription factor binding sites. Massively parallel reporter assays such as survey of regulatory elements (SuRE) provide an alternative way to study millions of promoter fragments in parallel. Here we show how a generalized linear model (GLM) can be used to transform genome-scale SuRE data into a high-resolution genomic track that quantifies the contribution of local sequence to promoter activity. This coefficient track helps identify regulatory elements and can be used to predict promoter activity of any sub-region in the genome. It thus allows in silico dissection of any promoter in the human genome to be performed. We developed a web application, available at cissector.nki.nl, that lets researchers easily perform this analysis as a starting point for their research into any promoter of interest.</p
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