Optimizing dual energy cone beam CT protocols for preclinical imaging and radiation research

Objective: The aim of this work was to investigate whether quantitative dual-energy CT (DECT) imaging is feasible for small animal irradiators with an integrated cone-beam CT (CBCT) system. Methods: The optimal imaging protocols were determined by analyzing different energy combinations and dose levels. The influence of beam hardening effects and the performance of a beam hardening correction (BHC) were investigated. In addition, two systems from different manufacturers were compared in terms of errors in the extracted effective atomic numbers (Z(eff)) and relative electron densities (rho(e)) for phantom inserts with known elemental compositions and relative electron densities. Results: The optimal energy combination was determined to be 50 and 90kVp. For this combination, Z(eff) and r rho(e) can be extracted with a mean error of 0.11 and 0.010, respectively, at a dose level of 60cGy. Conclusion: Quantitative DECT imaging is feasible for small animal irradiators with an integrated CBCT system. To obtain the best results, optimizing the imaging protocols is required. Well-separated X-ray spectra and a sufficient dose level should be used to minimize the error and noise for Z(eff) and rho(e). When no BHC is applied in the image reconstruction, the size of the calibration phantom should match the size of the imaged object to limit the influence of beam hardening effects. No significant differences in Z(eff) and rho(e) errors are observed between the two systems from different manufacturers. Advances in knowledge: This is the first study that investigates quantitative DECT imaging for small animal irradiators with an integrated CBCT system

A combined modeling and experimental study on low- and high-temperature oxidation chemistry of OME3 as novel fuel additive

International audienceThe present research focuses on combined modeling and experimental work on the com-bustion of oxymethylene ethers (OMEs). OMEs are promising synthetic fuels which can beproduced in a carbon-neutral manner starting from captured CO2 and renewable energy.Moreover, blending them with conventional diesel reduces soot emissions because of the ab-sence of carbon-carbon bonds. This results in less harmful emissions and contributes to amore sustainable transport sector as aimed by the Paris climate agreement objectives. Topromote the use of these kind of molecules as fuel additive, it is important to understand theirlow- and high-temperature combustion kinetics. The development of detailed microkineticmodels provides this fundamental insight and enables predictive simulations for combustionapplications.During the last decade, great progress has been made in the construction of reliable kineticmodels for numerous technologically important radical chemistry processes. The resultingmodels typically contain hundreds of species, and several thousands of associated reactions.The manual generation of microkinetic models would be a tedious, error prone and oftenincomplete process. To prevent this, automatic kinetic model generation routines have beendeveloped to systematically develop models, such as Genesys at the Laboratory for Chemi-cal Technology (Ghent University). A kinetic model for both oxidation and pyrolysis hasbeen developed for OME3 based on first principles using Genesys.A prerequisite for the generation of detailed kinetic models is the availability of accuratethermodynamic and kinetic data for species and reactions respectively. Ideally, these pa-rameters are available from experiments or high-level quantum chemical calculations. Sincethese methods are expensive and time-consuming, Genesys instead often relies on approxi-mation methods such as group additivity and rate rules. In this work, thermodynamic andkinetic parameters are obtained from quantum chemical calculations at the CBS-QB3 levelof theory for important reaction pathways for both low- and high- temperature oxidation ofOME3. The results of these calculations are extrapolated to be valid for long-chain OMEsby regression of new group additive values and rate rules.Within Genesys, the possible reactions are generally defined in terms of reaction families,e.g. hydrogen abstraction by molecular oxygen from a secondary carbon atom. Reactionfamilies from earlier studies on smaller oxymethylene ethers such as dimethoxy methaneare taken over and applied for the OME3 model. The outcome is a model containing thechemistry for OME3. To include the chemistry of smaller (oxygenated) hydrocarbons in thefinal model, the Genesys model is merged with the AramcoMech 1.3 base model.Both at ame burner and rapid compression machine experiments have been performedwith OME3 for validation of the combustion model. The ame experiments are performedat 0.053 bara and with a fuel composition of 20 mol% OME3 and 80 mol% CH4. Some mea-sured concentration profiles in function of the height above burner (HAB) of small species(i.e. OME3, CH2O, CH3OH, H2, CO2 and CO) are shown in Figure 1. Other impor-tant species which are observed include ethane, ethylene, dimethyl ether, methyl formate,dimethoxy methane and methoxymethyl formate.Ignition delay times have been measured via rapid compression at 5 bara for and to ad-ditionally validate the low-temperature section of the model. Samples were taken to identifythe reactants and products, including OME3, methyl formate, methoxymethyl formate andmethoxymethoxymethyl formate. Similarly, pyrolysis experiments are performed for OME3in a bench-scale steam cracker setup over a broad range of temperatures (723 K - 1073 K)to validate both the primary and secondary chemistry of the pyrolysis model

Accounting for Molecular Flexibility in Photoionization: Case of tert-Butyl Hydroperoxide

tert-butyl hydroperoxide (tBuOOH) is a common intermediate in the oxidation of organic compounds that needs to be accurately quantified in complex gas mixtures for the development of chemical kinetic models of low temperature combustion. This work presents a combined theoretical and experimental investigation on the synchrotron-based VUV single photon ionization of gas-phase tBuOOH in the 9.0 - 11.0 eV energy range, including dissociative ionization processes. Computations consist of the determination of the structures, vibrational frequencies and the energetics of neutral and ionic tBuOOH. The Franck-Condon spectrum for the tBuOOH+ (X+) + e- tBuOOH (X) +h transition is computed, where special treatment is undertaken because of the flexibility of tBuOOH, in particular regarding the OOH group. Through comparison of the experimental mass-selected threshold photoelectron spectra with explicitly correlated coupled cluster calculations and Franck-Condon simulations, thermochemical values are obtained as the adiabatic ionization energy and the appearance energy of the only fragment observed within the above-mentioned energy range, identified as the tert-butyl C4H9+. Finally, the signal branching ratio between the parent and the fragment ions is provided as a function of photon energy, essential to quantify tBuOOH in gas-phase oxidation/combustion experiments via advance mass spectrometry techniques

Medjez II

Ce gisement princeps du faciès « Sétifïen* » joue un rôle majeur dans la caractérisation de la variabilité capsienne de l’Epipaléolithique du Maghreb, observée entre le VIII-Ve millénaire cal BC. On doit à Henriette Camps-Fabrer d’avoir souligné les éléments diagnostics d’une abondante et nouvelle documentation régionale. Recueillie lors de plusieurs campagnes de fouilles (entre 1963 et 1968), cette documentation est conservée à Alger, au CNRPAH. Bien après la première monographie sur le Caps..

STE20 kinase TAOK3 regulates type 2 immunity and metabolism in obesity

Healthy adipose tissue (AT) contains ST2(+) Tregs, ILC2s, and alternatively activated macrophages that are lost in mice or humans on high caloric diet. Understanding how this form of type 2 immunity is regulated could improve treatment of obesity. The STE20 kinase Thousand And One amino acid Kinase-3 (TAOK3) has been linked to obesity in mice and humans, but its precise function is unknown. We found that ST2(+) Tregs are upregulated in visceral epididymal white AT (eWAT) of Taok3(-/-) mice, dependent on IL-33 and the kinase activity of TAOK3. Upon high fat diet feeding, metabolic dysfunction was attenuated in Taok3(-/-) mice. ST2(+) Tregs disappeared from eWAT in obese wild-type mice, but this was not the case in Taok3(-/-) mice. Mechanistically, AT Taok3(-/-) Tregs were intrinsically more responsive to IL-33, through higher expression of ST2, and expressed more PPAR & gamma; and type 2 cytokines. Thus, TAOK3 inhibits adipose tissue Tregs and regulates immunometabolism under excessive caloric intake. Maes et al. reveal an unexpected role of TAOK3 in regulating ST2(+) regulatory T cells in mouse adipose tissue. Absence of TAOK3 sustains Tregs in obesity and improves metabolic dysfunction

Death and the Societies of Late Antiquity

Ce volume bilingue, comprenant un ensemble de 28 contributions disponibles en français et en anglais (dans leur version longue ou abrégée), propose d’établir un état des lieux des réflexions, recherches et études conduites sur le fait funéraire à l’époque tardo-antique au sein des provinces de l’Empire romain et sur leurs régions limitrophes, afin d’ouvrir de nouvelles perspectives sur ses évolutions possibles. Au cours des trois dernières décennies, les transformations considérables des méthodologies déployées sur le terrain et en laboratoire ont permis un renouveau des questionnements sur les populations et les pratiques funéraires de l’Antiquité tardive, période marquée par de multiples changements politiques, sociaux, démographiques et culturels. L’apparition de ce qui a été initialement désigné comme une « Anthropologie de terrain », qui fut le début de la démarche archéothanatologique, puis le récent développement d’approches collaboratives entre des domaines scientifiques divers (archéothanatologie, biochimie et géochimie, génétique, histoire, épigraphie par exemple) ont été décisives pour le renouvellement des problématiques d’étude : révision d’anciens concepts comme apparition d’axes d’analyse inédits. Les recherches rassemblées dans cet ouvrage sont articulées autour de quatre grands thèmes : l’évolution des pratiques funéraires dans le temps, l’identité sociale dans la mort, les ensembles funéraires en transformation (organisation et topographie) et les territoires de l’empire (du cœur aux marges). Ces études proposent un réexamen et une révision des données, tant anthropologiques qu’archéologiques ou historiques sur l’Antiquité tardive, et révèlent, à cet égard, une mosaïque de paysages politiques, sociaux et culturels singulièrement riches et complexes. Elles accroissent nos connaissances sur le traitement des défunts, l’emplacement des aires funéraires ou encore la structure des sépultures, en révélant une diversité de pratiques, et permettent au final de relancer la réflexion sur la manière dont les sociétés tardo-antiques envisagent la mort et sur les éléments permettant d’identifier et de définir la diversité des groupes qui les composent. Elles démontrent ce faisant que nous pouvons véritablement appréhender les structures culturelles et sociales des communautés anciennes et leurs potentielles transformations, à partir de l’étude des pratiques funéraires.This bilingual volume proposes to draw up an assessment of the recent research conducted on funerary behavior during Late Antiquity in the provinces of the Roman Empire and on their borders, in order to open new perspectives on its possible developments. The considerable transformations of the methodologies have raised the need for a renewal of the questions on the funerary practices during Late Antiquity, a period marked by multiple political, social, demographic and cultural changes. The emergence field anthropology, which was the beginning of archaeothanatology, and then the recent development of collaborative approaches between various scientific fields (archaeothanatology, biochemistry and geochemistry, genetics, history, epigraphy, for example), have been decisive. The research collected in this book is structured around four main themes: Evolution of funerary practices over time; Social identity through death; Changing burial grounds (organisation and topography); Territories of the Empire (from the heart to the margins). These studies propose a review and a revision of the data, both anthropological and archaeological or historical on Late Antiquity, and reveal a mosaic of political, social, and cultural landscapes singularly rich and complex. In doing so, they demonstrate that we can truly understand the cultural and social structures of ancient communities and their potential transformations, based on the study of funerary practices

Colour ideophones in African languages: A typological approach

International audienceWe present the results of a large-scale typological survey of colour-related meanings expressed with ideophones in a sample of 106 African languages from various families and genetic stocks: Chadic, Cushitic (Afroasiatic), Khoe-Kwadi (Khoisan), Adamawa, Atlantic, Bantu, Dogon, Gur, Kordofanian, Kru, Kwa, Mande, Mel, Ubangi (Niger-Congo), Central Sudanic, Eastern Sudanic (Nilo-Saharan), and Songhai (varia). The data was mostly extracted from the RefLex online lexical database (Segerer & Flavier 2011-2018) by searching colours terms via translations together with grammatical categories. We will first discuss methodological issues related to the use of a lexical database for the purpose of discovering ideophones since there is a great diversity of terminology in the sources. We will discuss the decisions we took for retrieval purposes, specifically the issue of selecting items not labelled as ideophones. Such items were included insofar as they were formally and/or semantically akin to Ameka’s (2001: 26) working definition of ideophones. That includes:a) terms labelled as ideophones by the authors: pééb ideo. ‘very white’ (Akoose); jɔŋ ideo. ‘brown’ (Mende)b) terms labelled differently but fitting in with the working definition: pələk-pələkà adj. ‘very black’ (Bade, Chadic); córí adv.expr. ‘very red, bright red’ (Bambara, Mande); pál interjection ‘pure white’ (Bedik, Atlantic-North); ná tápatápa onom. ‘dark black’ (Duala, Bantu); kàrù adverb (degree modifier) ‘really red’ (Ma’di, Central Sudanic)c) any lexical item lacking the mention of its word category, and which combines specifically with a colour term, e.g. coy ‘in intensive expressions yeeq coy – yaxig coy to be very red; to be bright red’ (Wolof, Atlantic-North).We will then present the genetic and areal patterns of the some 1,000 ideophones (leaving out ‘multicoloured’, ‘spotted’ and the like) found in our sample, as well as their skewed distribution across the spectrum, and their semantic properties, especially their intensifying or attenuative function of “basic” colour terms.Since ideophones have been long claimed as being difficult to borrow (e.g. Childs 1994), but recently disclaimed as potentially borrowable because of the low degree of their morphosyntactic integration (Dingemanse 2017), we will end our presentation by the discussion of a specific case of lexical diffusion via borrowings from Fula within the Macro Sudan Belt area (Güldemann 2017) concerning the colours ‘black’, ‘white’ and ‘red’. It is possible to hypothesize the origin of the diffusion: in each case, only one language, namely Fula (Atlantic-North), in fact a cluster of languages spoken by nomadic people, are or have been in contact with the other 25 languages belonging to four branches of Niger-Congo (Atlantic-North, Mande, Dogon and Adamawa), to one Songhay (Varia) variety, and to one branch of Afro-Asiatic (Chadic)