Search results for "Graph"
showing 10 items of 55700 documents
Cave bear occupation in Schwabenreith Cave, Austria, during the early last glacial: constraints from 230 Th/U‐dated speleothems
2019
The cave bear was a prominent member of the Upper Pleistocene fauna in Eurasia. While breakthroughs were recently achieved with respect to its phylogeny using ancient DNA techniques, it is still challenging to date cave bear fossils beyond the radiocarbon age range. Without an accurate and precise chronological framework, however, key questions regarding the palaeoecology cannot be addressed, such as the extent to which large climate swings during the last glacial affected the habitat and possibly even conditioned the final extinction of this mammal. Key to constraining the age of cave bear fossils older than the lower limit of radiocarbon dating is to date interlayered speleothems using 23…
Hexakis(diethylacetamide)iron(II) hexahalorhenate(IV) ionic salts: X-ray structures and magnetic properties
2015
Two novel Fe<sup>II</sup>-Re<sup>IV</sup> compounds of general formula [Fe<sup>II</sup>(DEA)<inf>6</inf>][Re<sup>IV</sup>X<inf>6</inf>] where DEA = diethylacetamide and X = Cl (1) and Br (2) have been prepared and magnetostructurally characterised. Complexes 1 and 2 are isomorphic ionic salts that crystallise in the trigonal crystal system with space group R(-3). The rhenium(IV) ion in 1 and 2 is six-coordinate with six chloro (1) or bromo (2) ligands building a regular octahedral chromophore. The Fe<sup>II</sup> ion is also six-coordinate, and bonded to six oxygen atoms from six DEA molecules. [Fe<sup>…
Hard cap espresso extraction and liquid chromatography determination of bioactive compounds in vegetables and spices
2017
Abstract A new analytical procedure, based on liquid chromatography with diode array and fluorescence detection, has been proposed for the determination of bioactive compounds in vegetables and spices after hard cap espresso extraction. This novel extraction system has been tested for the determination of capsaicin and dihydrocapsaicin from fresh chilli and sweet pepper, piperine from ground pepper, curcumin from turmeric and curry, and myristicin from nutmeg. Extraction efficiency was evaluated by using acetonitrile:water and ethanol:water mixtures. The proposed method allows the extraction of samples with 100 mL of 60% (v/v) ethanol in water. The obtained limits of quantification for the …
Extensions and corona decompositions of low-dimensional intrinsic Lipschitz graphs in Heisenberg groups
2020
This note concerns low-dimensional intrinsic Lipschitz graphs, in the sense of Franchi, Serapioni, and Serra Cassano, in the Heisenberg group $\mathbb{H}^n$, $n\in \mathbb{N}$. For $1\leq k\leq n$, we show that every intrinsic $L$-Lipschitz graph over a subset of a $k$-dimensional horizontal subgroup $\mathbb{V}$ of $\mathbb{H}^n$ can be extended to an intrinsic $L'$-Lipschitz graph over the entire subgroup $\mathbb{V}$, where $L'$ depends only on $L$, $k$, and $n$. We further prove that $1$-dimensional intrinsic $1$-Lipschitz graphs in $\mathbb{H}^n$, $n\in \mathbb{N}$, admit corona decompositions by intrinsic Lipschitz graphs with smaller Lipschitz constants. This complements results that…
Adjusting the Knox test by accounting for spatio-temporal crime risk heterogeneity to analyse near-repeats
2020
The near-repeat phenomenon usually occurs with any crime. Hence, to implement preventive measures, it is of great interest to figure out at which spatio-temporal scale crimes are more likely to be repeated by offenders. The Knox test is the most used statistical tool for evaluating the presence of the near-repeat phenomenon given a dataset of crimes that are located in space and time. The classic version of this test assumes that crime risk is homogeneous in both space and time, although this assumption rarely holds in reality. Therefore, the main goal of this article is to highlight the necessity of adjusting the standard version of the Knox test, including spatial and temporal effects th…
Adjacency matrices of random digraphs: singularity and anti-concentration
2017
Let ${\mathcal D}_{n,d}$ be the set of all $d$-regular directed graphs on $n$ vertices. Let $G$ be a graph chosen uniformly at random from ${\mathcal D}_{n,d}$ and $M$ be its adjacency matrix. We show that $M$ is invertible with probability at least $1-C\ln^{3} d/\sqrt{d}$ for $C\leq d\leq cn/\ln^2 n$, where $c, C$ are positive absolute constants. To this end, we establish a few properties of $d$-regular directed graphs. One of them, a Littlewood-Offord type anti-concentration property, is of independent interest. Let $J$ be a subset of vertices of $G$ with $|J|\approx n/d$. Let $\delta_i$ be the indicator of the event that the vertex $i$ is connected to $J$ and define $\delta = (\delta_1, …
A combined three-dimensional digitisation and subsurface defect detection data using active infrared thermography
2016
International audience; In recent years, NonDestructive Testing (NDT) systems have been upgraded with three-dimensional information. Indeed, combine the three-dimensional and thermal information allows a more meaningful analysis. In the literature, the data for NDT and three-dimensional (3D) reconstruction analysis are commonly acquired from independent systems. However, the use of two such systems leads to error analysis during the data registration. In an attempt to overcome such problems, we propose a single system based on active thermography approach using heat point-source stimulation to get the 3D digitization as well as subsurface defect detection. The experiments are conducted on s…
Molecular association of cryptand 221D in NaCl-water solutions. A small-angle neutron scattering study
1993
Molecules of 5-Decyl-4,7,13,16,21-pentaoxa-1,10-diaza-bicyclo-[8.8.5.]tricosan (221D) and its sodium complex, with both a hydrophobic and a hydrophilic portion, are expected to form aggregates in water solutions. This was confirmed by surface tension measurements. The aggregation behaviour was studied by small-angle neutron scattering at two different [NaCl]/[221D] molar ratios, such as to obtain, in one case, aggregates entirely made up of ionic monomers, and in the other, mixed micelles constituted by both ionic and non-ionic units. The variation of the aggregation number and number of aggregates indicated that, in the former case, smaller micelles were formed, as a consequence of repulsi…
First principles hybrid Hartree-Fock-DFT calculations of bulk and (001) surface F centers in oxide perovskites and alkaline-earth fluorides
2020
Valuable discussions with E. A. Kotomin are gratefully acknowledged. Research contribution of R. E. and A. I. P. has been performed within the framework of the EUROfusion Enabling Research project: ENR-MFE19.ISSP-UL-02 “Advanced experimental and theoretical analysis of defect evolution and structural disordering in optical and dielectric materials for fusion applications.” The views and opinions expressed herein do not necessarily reflect those of the European Commission.
Enduring Sacred Places: The Astronomical Orientation of the Iberian Cave-Sanctuary of Cueva Santa del Cabriel in Spain
2019
This paper presents the results of an archaeoastronomical study of the Iberian Iron Age cave-sanctuary of Cueva Santa del Cabriel, near the town of Mira in the province of Cuenca, Castilla-La Mancha, central Spain, together with a review of the latest archaeological and ethnographical data about the site. We found that the cave's 12 m-long access corridor is oriented precisely along the summer solstice sunset, so that the north wall of the main gallery is partially illuminated by sunlight at this time. Although the cave was in use from the Late Chalcolithic, it became an important religious centre in the Iberian period. After an apparent hiatus during the Roman and Islamic occupations, its …