859 research outputs found
Towards Uniform Gene Bank Documentation In Europe – The Experience From The EFABISnet Project
In the EFABISnet project, a collaborative effort of EAAP, FAO and partners from 14 European countries, in cooperation with the European Regional Focal Point for Animal Genetic Resources (ERFP), national information systems for monitoring the animal genetic resources on breed level were established in Austria, Cyprus, Estonia, Georgia, Iceland, Ireland, Italy, Netherlands, Slovakia, Slovenia, Switzerland, and United Kingdom. The network was soon extended beyond the project plans, with the establishment of EFABIS databases in Finland, Greece, and Hungary. The network was then complemented by a set of inventories of national gene bank collections to strengthen the documentation of ex situ conservation programmes. These documentation systems were established by the National Focal Points for management of farm animal genetic resources. Here we present the experience gained in establishment of these national inventories of gene banks and their relevance to the Strategic Priority Areas of the Global Plan of Action which could be useful for other areas in the world
The seawater neodymium and lead isotope record of the final stages of Central American Seaway closure
Key Points:
Seawater Nd and Pb isotope records for the Pliocene Caribbean and EEP
Caribbean Nd isotope composition became more UNADW-like during the Pliocene
Short term changes support link between CAS closure and strength of AMOC
The shoaling and final closure of the Central American Seaway (CAS) resulted in a major change of the global ocean circulation and has been suggested as an essential driver for strengthening of Atlantic Meridional Overturning Circulation (AMOC). The exact timing of CAS closure is key to interpreting its importance. Here we present a reconstruction of deep and intermediate water Nd and Pb isotope compositions obtained from fossil fish teeth and the authigenic coatings of planktonic foraminifera in the eastern equatorial Pacific (ODP Site 1241) and the Caribbean (ODP Sites 998, 999 and 1000) covering the final stages of CAS closure between 5.6 and 2.2 Ma. The data for the Pacific site indicate no significant Atlantic/Caribbean influence over this entire period. The Caribbean sites show a continuous trend to less radiogenic Nd isotope compositions during the Pliocene, consistent with an enhancement of Upper North Atlantic Deep Water (UNADW) inflow and a strengthening of the AMOC. Superimposed onto this long-term trend, shorter-term changes of intermediate Caribbean Nd isotope signatures approached more UNADW-like values during intervals when published reconstructions of seawater salinity suggested complete closure of the CAS. The data imply that significant deep water exchange with the Pacific essentially stopped by 7 Ma and that shallow exchange, which still occurred at least periodically until approximately 2.5 Ma, may have been linked to the strength of the AMOC but did not have any direct effect on the intermediate and deep Caribbean Nd isotope signatures through mixing with Pacific waters
ICARES: a real-time automated detection tool for clusters of infectious diseases in the Netherlands.
Clusters of infectious diseases are frequently detected late. Real-time, detailed information about an evolving cluster and possible associated conditions is essential for local policy makers, travelers planning to visit the area, and the local population. This is currently illustrated in the Zika virus outbreak
Photochromism in Ruddlesden-Popper copper-based perovskites:A light-induced change of coordination number at the surface
Ruddlesden-Popper organic-inorganic hybrid copper-based perovskites have been studied for decades owing to a variety of interesting properties, such as thermochromism and piezochromism, and the mechanisms behind these phenomena have been explained. Another possible property of these materials that has seldomly been investigated is photochromism. In this work, the photochromic properties of bis(phenethylammonium) tetrachlorocuprate (also known as phenethylammonium copper chloride) are reported for the first time. This material has attracted scientific interest owing to the fact that it shows both ferroelectric and ferromagnetic behavior. This work highlights the difference in stability between two Ruddlesden-Popper copper-based perovskites - with phenethylammonium (PEA) or methylammonium (MA) as the cations - during external stimuli. Various techniques, such as Raman and X-ray photoelectron spectroscopy, and grazing-incidence wide-angle X-ray scattering, combined with optical studies, were used to investigate the underlying photochemical processes at a molecular level. It is found that for the PEA compound, ultraviolet illumination causes a color change from yellow to brown. This is the result of two independent events, namely a Cu2+ reduction reaction and a transition from an octahedral copper-chloride structure to square-planar CuCl42-. After illumination, the material (brown color) is unstable in air, which is evident from a color change back to yellow. Interestingly, the similar compound bis(methylammonium) tetrachlorocuprate does not display photochromic behavior, which is attributed to the different nature of the two organic cations
Size-Dependent Surface Plasmon Dynamics in Metal Nanoparticles
We study the effect of Coulomb correlations on the ultrafast optical dynamics
of small metal particles. We demonstrate that a surface-induced dynamical
screening of the electron-electron interactions leads to quasiparticle
scattering with collective surface excitations. In noble-metal nanoparticles,
it results in an interband resonant scattering of d-holes with surface
plasmons. We show that this size-dependent many-body effect manifests itself in
the differential absorption dynamics for frequencies close to the surface
plasmon resonance. In particular, our self-consistent calculations reveal a
strong frequency dependence of the relaxation, in agreement with recent
femtosecond pump-probe experiments.Comment: 8 pages + 4 figures, final version accepted to PR
Acute lung injury after aortic surgery: the relation between lung and leg microvascular permeability to III Indium-labeled transferin and circulating mediators
Ninth and Tenth Order Virial Coefficients for Hard Spheres in D Dimensions
We evaluate the virial coefficients B_k for k<=10 for hard spheres in
dimensions D=2,...,8. Virial coefficients with k even are found to be negative
when D>=5. This provides strong evidence that the leading singularity for the
virial series lies away from the positive real axis when D>=5. Further analysis
provides evidence that negative virial coefficients will be seen for some k>10
for D=4, and there is a distinct possibility that negative virial coefficients
will also eventually occur for D=3.Comment: 33 pages, 12 figure
Size-dependent Correlation Effects in Ultrafast Optical Dynamics of Metal Nanoparticles
We study the role of collective surface excitations in the electron
relaxation in small metal particles. We show that the dynamically screened
electron-electron interaction in a nanoparticle contains a size-dependent
correction induced by the surface. This leads to new channels of quasiparticle
scattering accompanied by the emission of surface collective excitations. We
calculate the energy and temperature dependence of the corresponding rates,
which depend strongly on the nanoparticle size. We show that the
surface-plasmon-mediated scattering rate of a conduction electron increases
with energy, in contrast to that mediated by a bulk plasmon. In noble-metal
particles, we find that the dipole collective excitations (surface plasmons)
mediate a resonant scattering of d-holes to the conduction band. We study the
role of the latter effect in the ultrafast optical dynamics of small
nanoparticles and show that, with decreasing nanoparticle size, it leads to a
drastic change in the differential absorption lineshape and a strong frequency
dependence of the relaxation near the surface plasmon resonance. The
experimental implications of our results in ultrafast pump-probe spectroscopy
are also discussed.Comment: 29 pages including 6 figure
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