1,181 research outputs found
Lab-on-a-chip platforms based on highly sensitive nanophotonic Si biosensors for single nucleotide DNA testing
In order to solve the drawbacks of sensitivity and portability in optical biosensors we have developed ultrasensitive and miniaturized photonic silicon sensors able to be integrated in a "lab-on-a-chip" microsystem platform. The sensors are integrated Mach-Zehnder interferometers based on TIR optical waveguides (Si/SiO2/Si3N4) of micro/nanodimensions. We have applied this biosensor for DNA testing and for detection of single nucleotide polymorphisms at BRCA-1 gene, involved in breast cancer development, without target labeling. The oligonucleotide probe is immobilized by covalent attachment to the sensor surface through silanization procedures. The hybridization was performed for different DNA target concentrations showing a lowest detection limit at 10 pM. Additionally, we have detected the hybridization of different concentrations of DNA target with two mismatching bases corresponding to a mutation of the BRCA-1 gene. Following the way of the lab-on-a-chip microsystem, integration with the microfluidics has been achieved by using a novel fabrication method of 3-D embedded microchannels using the polymer SU-8 as structural material. The optofluidic chip shows good performances for biosensing
Analysis of Farmland Abandonment and the Extent and Location of Agricultural Areas that are Actually Abandoned or are in Risk to be Abandoned
Farmland abandonment (FLA) can be defined as the cessation of agricultural activities on a given surface of land and not taken by another activity (such as urbanisation or afforestation). This process attracts the attention of policy-makers both at national and EU level, in particular within the context of the Rural Development Policy. And, considering its importance in environmental and socio-economic terms, it is necessary to better understand the geographic distribution and strength of farmland abandonment trends in the EU-27, and to develop indicators to identify the most important farmland abandonment tendencies.
The first aim of this study was to establish the state of the art concerning farmland abandonment (definition, type) and methodologies for identifying/quantifying this phenomenon (dataset, period of analysis, scale). Then, it was about contributing to a new definition of Less Favoured Areas by assessing the driving forces of farmland abandonment and preparing the guidelines for agri-environmental indicator Nr 14 [COM2006 (508final)] by evaluating the state and risk of farmland abandonment.
The proposed methodology was based on two main elements: the variation of the UAA and the definition of rural areas. After identifying clear definitions for each variable, the way to consider the main flows of land use changes was studied. Due to a lack of accurate data at the appropriate scale, farmland afforestation could not be separated from the flow of FLA and the flow from farmland to sealed soil was estimated based on the hypothesis that it was mainly located in urban areas where the population density is high or increases very fast.
The methodology was tested in three of the main agricultural countries in the EU-27 in terms of surface (France, Spain and Poland). Then, five regions were chosen to cover different contexts where a high level of FLA was observed and interviews of experts and stakeholders completed the study. Based on the results on the main causes of FLA, indicators of risk were proposed and recommendations were formulated to improve the methodology and datasets.JRC.H.5-Rural, water and ecosystem resource
X-ray topographic determination of the granular structure in a graphite mosaic crystal: a three-dimensional reconstruction
Section topographs recorded at different spatial locations and at different rocking angles of a highly oriented pyrolytic graphite (HOPG) crystal allow three-dimensional maps of the local angular-dependent scattering power to be obtained. This is performed with a direct reconstruction from the intensity distribution on such topographs. The maps allow the extraction of information on local structural parameters such as size, form and internal mosaic spread of crystalline domains. This data analysis leads to a new method for the characterization of mosaic crystals. Perspectives and limits of applicability of this method are discussed
X-ray topographic determination of the granular structure in a graphite mosaic crystal : a three-dimensional reconstruction
Section topographs recorded at different spatial locations and at different rocking angles of a highly oriented pyrolytic graphite (HOPG) crystal allow three-dimensional maps of the local angular-dependent scattering power to be obtained. This is performed with a direct reconstruction from the intensity distribution on such topographs. The maps allow the extraction of information on local structural parameters such as size, form and internal mosaic spread of crystalline domains. This data analysis leads to a new method for the characterization of mosaic crystals. Perspectives and limits of applicability of this method are discussed
A Hybrid Approach to Parallel Pattern Discovery in C++
Funding: EU Horizon 2020 project, TeamPlay, grant number 779882, and UK EPSRC Discovery, grant number EP/P020631/1.Parallel pattern libraries offer a strong combination of abstraction and performance. However, discovering places in sequential code where parallel patterns should be introduced is still highly non-trivial, often requiring expert manual analysis and profiling. We present a hybrid discovery technique to detect instances of parallel patterns in sequential code. This employs both static and dynamic trace-based analysis, together with hotspot detection. We evaluate our pattern discovery mechanism on a number of representative benchmarks. We evaluate the performance of the resulting parallelised benchmarks on a 24-core parallel machine.Postprin
Precision determination of the dpi -> NN transition strength at threshold
An unusual but effective way to determine at threshold the dpi -> NN
transition strength is to exploit the hadronic ground-state broadening in
pionic deuterium, accessible by x-ray spectroscopy. The broadening is dominated
by the true absorption channel dpi- -> nn, which is related to s-wave pion
production pp -> dpi+ by charge symmetry and detailed balance. Using the exotic
atom circumvents the problem of Coulomb corrections to the cross section as
necessary in the production experiments. Our dedicated measurement finds
(1171+23/-49) meV for the broadening yielding (252+5/-11) \mub.Comment: 4 pages, 2 figures, 1 tabl
Shadow monochromatic backlighting: Large-field high resolution X-ray shadowgraphy with improved spectral tunability
The shadow monochromatic backlighting (SMB) scheme, a modification
of the well-known soft X-ray monochromatic backlighting scheme,
is proposed. It is based on a spherical crystal as the dispersive
element and extends the traditional scheme by allowing one to
work with a wide range of Bragg angles and thus in a wide spectral
range. The advantages of the new scheme are demonstrated
experimentally and supported numerically by ray-tracing
simulations. In the experiments, the X-ray backlighter source
is a laser-produced plasma, created by the interaction of an
ultrashort pulse, Ti:Sapphire laser (120 fs, 3–5 mJ,
1016 W/cm2 on target) or a short wavelength
XeCl laser (10 ns, 1–2 J, 1013 W/cm2 on
target) with various solid targets (Dy, Ni + Cr, BaF2).
In both experiments, the X-ray sources are well localized spatially
(∼20 μm) and are spectrally tunable in a relatively wide
wavelength range (λ = 8–15 Å). High quality monochromatic
(δλ/λ ∼ 10−5–10−3)
images with high spatial resolution (up to ∼4 μm) over a large field
of view (a few square millimeters) were obtained. Utilization
of spherically bent crystals to obtain high-resolution, large
field, monochromatic images in a wide range of Bragg angles
(35° < Θ < 90°) is demonstrated for the first
time
PhyloFlu, a DNA Microarray for Determining the Phylogenetic Origin of Influenza A Virus Gene Segments and the Genomic Fingerprint of Viral Strains
X-ray scatter measurements from thermally slumped thin glass substrates for the HEFT hard x-ray telescopes
We have performed x-ray specular reflectivity and scattering measurements of thermally slumped glass substrates on x-ray diffractometers utilizing a rotating anode x-ray source at the Danish Space Research Institute (DSRI) and synchrotron radiation at the European Synchrotron Radiation Facility (ESRF) optics Bending Magnet beamline. In addition, we tested depth graded W/Si multilayer-coated slumped glass using x-ray specular reflectivity measurements at 8.048 keV and 28 keV and energy-dispersive measurements in the 20-50 keV rang at a double-axis diffractometer at the Orsted Laboratory, University of Copenhagen. The thermally slumped glass substrates will be used to fabricate the hard x-ray grazing incidence optics for the High-Energy Focusing Telescope. We compared the measurements to the SODART- mirrors from the SRG telescope mission program. The surface scatter measurement of the thermally slumped glass substrates yields Half Power Diameters (HPD's) of single- bounce mirrors of full-illuminated lengths of ~ 40 arcseconds for typical substrates and as low as ~ 10 arcseconds for the best substrates, whereas the SODART mirrors yields HPD's of ~ 80 arcseconds with very little variation. Both free-standing glass substrates and prototype mounted and multilayer-coated optics were tested. The result demonstrate that the surface scatter contribution, plus any contribution from the mounting procedure, to the Half Power Diameter from a telescope using the slumped glass optics will be in the subarcminute range.In addition we measured low surface microroughness, yielding high reflectivity, from the glass substrates, as well as from the depth graded W/Si multilayer-coated glass glass (interfacial width 4.2 Å)
A New Scheme for Stigmatic X-ray Imaging with Large Magnification
This paper describes a new x-ray scheme for stigmatic imaging. The scheme consists of one convex spherically bent crystal and one concave spherically bent crystal. The radii of curvature and Bragg reflecting lattice planes of the two crystals are properly matched to eliminate the astigmatism, so that the conditions for stigmatic imaging are met for a particular wavelength. The magnification is adjustable and solely a function of the two Bragg angles or angles of incidence. Although the choice of Bragg angles is constrained by the availability of crystals, this is not a severe limitation for the imaging of plasmas, since a particular wavelength can be selected from the bremsstrahlung continuum. The working principle of this imaging scheme has been verified with visible light. Further tests with x rays are planned for the near future. 2012 American Institute of Physic
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