78 research outputs found
Three-Particle Correlations in Simple Liquids
We use video microscopy to follow the phase-space trajectory of a
two-dimensional colloidal model liquid and calculate three-point correlation
functions from the measured particle configurations. Approaching the
fluid-solid transition by increasing the strength of the pair-interaction
potential, one observes the gradual formation of a crystal-like local order due
to triplet correlations, while being still deep inside the fluid phase.
Furthermore, we show that in a strongly interacting system the Born-Green
equation can be satisfied only with the full triplet correlation function but
not with three-body distribution functions obtained from superposing
pair-correlations (Kirkwood superposition approximation).Comment: 4 pages, submitted to PRL, experimental paper, 2nd version: Fig.1 and
two new paragraphs have been adde
Targetâoriented habitat and wildlife management: estimating forage quantity and quality of semiânatural grasslands with Sentinelâ1 and Sentinelâ2 data
Semiânatural grasslands represent ecosystems with high biodiversity. Their conservation depends on the removal of biomass, for example, through grazing by livestock or wildlife. For this, spatially explicit information about grassland forage quantity and quality is a prerequisite for efficient management. The recent advancements of the Sentinel satellite mission offer new possibilities to support the conservation of semiânatural grasslands. In this study, the combined use of radar (Sentinelâ1) and multispectral (Sentinelâ2) data to predict forage quantity and quality indicators of semiânatural grassland in Germany was investigated. Field data for organic acid detergent fibre concentration (oADF), crude protein concentration (CP), compressed sward height (CSH) and standing biomass dry weight (DM) collected between 2015 and 2017 were related to remote sensing data using the random forest regression algorithm. In total, 102 opticalâ and radarâbased predictor variables were used to derive an optimized dataset, maximizing the predictive power of the respective model. High R2 values were obtained for the grassland quality indicators oADF (R2 = 0.79, RMSE = 2.29%) and CP (R2 = 0.72, RMSE = 1.70%) using 15 and 8 predictor variables respectively. Lower R2 values were achieved for the quantity indicators CSH (R2 = 0.60, RMSE = 2.77 cm) and DM (R2 = 0.45, RMSE = 90.84 g/mÂČ). A permutationâbased variable importance measure indicated a strong contribution of simple ratioâbased optical indices to the model performance. In particular, the ratios between the narrow nearâinfrared and redâedge region were among the most important variables. The model performance for oADF, CP and CSH was only marginally increased by adding Sentinelâ1 data. For DM, no positive effect on the model performance was observed by combining Sentinelâ1 and Sentinelâ2 data. Thus, optical Sentinelâ2 data might be sufficient to accurately predict forage quality, and to some extent also quantity indicators of semiânatural grassland
Triplet correlations in two-dimensional colloidal model liquids
Three-body distribution functions in classical fluids have been theoretically
investigated many times, but have never been measured directly. We present
experimental three-point correlation functions that are computed from particle
configurations measured by means of video-microscopy in two types of
quasi-two-dimensional colloidal model fluids: a system of charged colloidal
particles and a system of paramagnetic colloids. In the first system the
particles interact via a Yukawa potential, in the second via a potential
. We find for both systems very similar results: on increasing
the coupling between the particles one observes the gradual formation of a
crystal-like local order due to triplet correlations, even though the system is
still deep inside the fluid phase. These are mainly packing effects as is
evident from the close resemblance between the results for the two systems
having completely different pair-interaction potentials.Comment: many pages, 8 figures, contribution to the special issue in J.Phys.
Cond. Mat. of the CECAM meeting in LYON ''Many-body....'
Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius
We report the discovery of very shallow (DF/F = 3.4 10-4), periodic dips in
the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite,
which we interpret as due to the presence of a transiting companion. We
describe the 3-colour CoRoT data and complementary ground-based observations
that support the planetary nature of the companion. Methods. We use CoRoT color
information, good angular resolution ground-based photometric observations in-
and out- of transit, adaptive optics imaging, near-infrared spectroscopy and
preliminary results from Radial Velocity measurements, to test the diluted
eclipsing binary scenarios. The parameters of the host star are derived from
optical spectra, which were then combined with the CoRoT light curve to derive
parameters of the companion. We examine carefully all conceivable cases of
false positives, and all tests performed support the planetary hypothesis.
Blends with separation larger than 0.40 arcsec or triple systems are almost
excluded with a 8 10-4 risk left. We conclude that, as far as we have been
exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which
we derive a period of 0.853 59 +/- 3 10-5 day and a radius of Rp = 1.68 +/-
0.09 REarth. Analysis of preliminary radial velocity data yields an upper limit
of 21 MEarth for the companion mass, supporting the finding.
CoRoT-7b is very likely the first Super-Earth with a measured radius.Comment: Accepted in Astronomy and Astrophysics; typos and language
corrections; version sent to the printer w few upgrade
Exceptional ancient DNA preservation and fibre remains of a Sasanian saltmine sheep mummy in ChehrÄbÄd, Iran
Funder: FP7 Ideas: European Research Council; Id: http://dx.doi.org/10.13039/100011199; Grant(s): 295729-CodeXMummified remains have long attracted interest as a potential source of ancient DNA. However, mummification is a rare process that requires an anhydrous environment to rapidly dehydrate and preserve tissue before complete decomposition occurs. We present the whole-genome sequences (3.94 X) of an approximately 1600-year-old naturally mummified sheep recovered from ChehrÄbÄd, a salt mine in northwestern Iran. Comparative analyses of published ancient sequences revealed the remarkable DNA integrity of this mummy. Hallmarks of postmortem damage, fragmentation and hydrolytic deamination are substantially reduced, likely owing to the high salinity of this taphonomic environment. Metagenomic analyses reflect the profound influence of high-salt content on decomposition; its microbial profile is predominated by halophilic archaea and bacteria, possibly contributing to the remarkable preservation of the sample. Applying population genomic analyses, we find clustering of this sheep with Southwest Asian modern breeds, suggesting ancestry continuity. Genotyping of a locus influencing the woolly phenotype showed the presence of an ancestral âhairyâ allele, consistent with hair fibre imaging. This, along with derived alleles associated with the fat-tail phenotype, provides genetic evidence that Sasanian-period Iranians maintained specialized sheep flocks for different uses, with the âhairyâ, âfat-tailedâ-genotyped sheep likely kept by the rural community of ChehrÄbÄd's miners
The value of health care â a matter of discussion in Germany
BACKGROUND: Interest in assessing the value of health-care services in Germany has considerably increased since the foundation of the Institut fĂŒr QualitĂ€t und Wirtschaftlichkeit im Gesundheitswesen, IQWiG (Institute for Quality and Efficiency in Health Care). The practical application of value assessment illustrates how problematic the process can be. In all decisions made for the provision of health care, data concerning the measurable dimensions (quantity and quality of efficacy and effectiveness, validity of the results and costs) flow into a complex and not yet standardized decision-making process concerning public financing. Some of these decisions are based on data of uncertain validity, unknown reproducibility and unclear appropriateness. DISCUSSION: In this paper we describe the theoretical aspects of value from psychological and economic viewpoints and discuss national and international approaches. Methodic details and difficulties in assessing the value of health-care services are analysed. A definition of the intangible value of health-care services will be proposed which contains only three factors: the absolute risk reduction (usually a measure of efficacy), the validity of the scientific papers examined and the type of the expected effectiveness (prevention of death and disability, restitution of well-being). The intangible value describes the additional benefit when comparing two possible actions, like treatment or observation only. CONCLUSION: The description of intangible value from the viewpoint of different stakeholders is a useful measure for subsequent steps (not discussed here) â the evaluation of costs and of patient benefit. A standardised, transparent, fair and democratic evaluation is essential for the definition of a basic benefit package
Towards eco-friendly crop protection: natural deep eutectic solvents and defensive secondary metabolites
Plant science
Modelling human choices: MADeM and decisionâmaking
Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)
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