On Algorithms Based on Joint Estimation of Currents and Contrast in Microwave Tomography

This paper deals with improvements to the contrast source inversion method which is widely used in microwave tomography. First, the method is reviewed and weaknesses of both the criterion form and the optimization strategy are underlined. Then, two new algorithms are proposed. Both of them are based on the same criterion, similar but more robust than the one used in contrast source inversion. The first technique keeps the main characteristics of the contrast source inversion optimization scheme but is based on a better exploitation of the conjugate gradient algorithm. The second technique is based on a preconditioned conjugate gradient algorithm and performs simultaneous updates of sets of unknowns that are normally processed sequentially. Both techniques are shown to be more efficient than original contrast source inversion.Comment: 12 pages, 12 figures, 5 table

Les veuves dans la ville en France au xixe siècle : images, rôles, types sociaux

Le veuvage féminin est beaucoup mieux connu pour la période moderne que pour le xixe siècle. Les représentations de la veuve, fondées sur trois héritages (la « Sainte veuve », la victime à secourir, la veuve légère) évoluent lentement au xixe siècle : d’un côté, elles favorisent une prise en charge collective de ce risque au siècle suivant ; de l’autre, elles insistent sur le danger que la veuve fait courir à l’ordre masculin. La veuve est très encadrée (voire longtemps exclue des funérailles), son comportement surveillé (attitudes, vêtements) et ses pouvoirs limités, en regard de l’Ancien Régime, par des codes discriminatoires. Mais ces derniers méritent d’être confrontés à la pratique juridique, notamment notariale, visant à améliorer le sort du conjoint survivant (contrats de mariage, pas si minoritaires qu’on l’a dit), et à la diffusion réelle de ces normes dans les familles. La forte présence des veuves dans la vie économique et sociale, celles qui surmontent ces ruptures familiales, révélerait une autre image des femmes, en particulier en ville. Un bref essai de typologie des veuves clôt l’article.Widowhood is much better known in France before 1800 than after. The representations of the widow are based upon three inheritances (the “holy widow”, the poor victim and the “merry widow”) and unfold during 19th century: on one hand, widowhood is more and more considered as a social risk; on the other, widow is seen as a danger for patriarcal order. She is strictly framed (often excluded from public funerals), her behaviour observed (clothing, attitudes) and her power limited by discriminatory “Code civil”. However, legal rules must be confronted to their practical applications in the families and to accomodations specially found by the “notaires” (wedding contracts, life insurance…). The strong presence of the widows in economy and society, particularly those who overcame their familial rupture, can reveal another image of the women, specially in towns. A short try of typology of the widows is given in the end

La bibliothèque en 8 questions

Notre enquête se poursuit avec quatre écrivains venus d\u27horizons très différents, mais que réunit leur goût pour les plaisirs de la tabl

Synthesis and (spectro)electrochemistry of mixedvalent diferrocenyl–dihydrothiopyran derivatives

Three novel diferrocenyl complexes were prepared and characterised. 2,2-Diferrocenyl-4,5-dimethyl- 3,6-dihydro-2H-thiopyran (1, sulphide) was accessible by the hetero-Diels–Alder reaction of diferrocenyl thioketone with 2,3-dimethyl-1,3-butadiene. Stepwise oxidation of 1 gave the respective oxides 2,2- diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1-oxide (2, sulfoxide) and 2,2-diferrocenyl-4,5- dimethyl-3,6-dihydro-2H-thiopyran-1,1-dioxide (3, sulfone), respectively. The molecular structures of 1 and 3 in the solid state were determined by single crystal X-ray crystallography. The oxidation of sulphide 1 to sulfone 3, plays only a minor role on the overall structure of the two compounds. Electrochemical (cyclic voltammetry (= CV), square wave voltammetry (= SWV)) and spectroelectrochemical (in situ UV-Vis/NIR spectroscopy) studies were carried out. The CV and SWV measurements showed that an increase of the sulphur atom oxidation from −2 in 1 to +2 in 3 causes an anodic shift of the ferrocenylbased oxidation potentials of about 100 mV. The electrochemical oxidation of 1–3 generates mixedvalent cations 1+–3+. These monooxidised species display low-energy electronic absorption bands between 1000 and 3000 nm assigned to IVCT (= Inter-Valence Charge Transfer) electronic transitions. Accordingly, the mixed-valent cations 1+–3+ are classified as weakly coupled class II systems according to Robin and Day.Authors (K. K. and G. M.) thank the National Science Centre (Poland) for financial support (Project Maestro-3; Dec-2012/06/ A/ST5/00219) and R. C. thanks the German Federal Ministry of Education and Research (BMBF) for support. The support from the German Academic Exchange Service (DAAD) in the framework of the exchange program “Ostpartnerschaften” is highly appreciated

Le FORUM, Vol. 38 No. 1

https://digitalcommons.library.umaine.edu/francoamericain_forum/1040/thumbnail.jp

Assisted reproductive techniques do not impact late neurodevelopmental outcomes of preterm children

ObjectiveAssisted reproductive technology (ART) increases the rate of preterm births, though few studies have analyzed outcomes for these infants. No data are available on 4-year-old children born prematurely after ART. The objective was to investigate whether ART affect the neurodevelopmental outcomes at 4 years in preterm infants born before 34 weeks of gestational age (GA).Methods and resultsA total of 166 ART and 679 naturally conceived preterm infants born before 34 weeks GA between 2013 and 2015 enrolled in the Loire Infant Follow-up Team were included. Neurodevelopment was assessed at 4 years using the age and stage questionnaire (ASQ) and the need for therapy services. The association between the socio-economic and perinatal characteristics and non-optimal neurodevelopment at 4 years was estimated. After adjustment, the ART preterm group remained significantly associated with a lower risk of having at least two domains in difficulty at ASQ: adjusted odds ratio (aOR) 0.34, 95% confidence interval (CI) (0.13–0.88), p = 0.027. The factors independently associated with non-optimal neurodevelopment at 4 years were male gender, low socio-economic level, and 25–30 weeks of GA at birth. The need for therapy services was similar between groups (p = 0.079). The long-term neurodevelopmental outcomes of preterm children born after ART are very similar, or even better than that of the spontaneously conceived children

Horizontal DNA transfer mechanisms of bacteria as weapons of intragenomic conflict

Horizontal DNA transfer (HDT) is a pervasive mechanism of diversification in many microbial species, but its primary evolutionary role remains controversial. Much recent research has emphasised the adaptive benefit of acquiring novel DNA, but here we argue instead that intragenomic conflict provides a coherent framework for understanding the evolutionary origins of HDT. To test this hypothesis, we developed a mathematical model of a clonally descended bacterial population undergoing HDT through transmission of mobile genetic elements (MGEs) and genetic transformation. Including the known bias of transformation toward the acquisition of shorter alleles into the model suggested it could be an effective means of counteracting the spread of MGEs. Both constitutive and transient competence for transformation were found to provide an effective defence against parasitic MGEs; transient competence could also be effective at permitting the selective spread of MGEs conferring a benefit on their host bacterium. The coordination of transient competence with cell-cell killing, observed in multiple species, was found to result in synergistic blocking of MGE transmission through releasing genomic DNA for homologous recombination while simultaneously reducing horizontal MGE spread by lowering the local cell density. To evaluate the feasibility of the functions suggested by the modelling analysis, we analysed genomic data from longitudinal sampling of individuals carrying Streptococcus pneumoniae. This revealed the frequent within-host coexistence of clonally descended cells that differed in their MGE infection status, a necessary condition for the proposed mechanism to operate. Additionally, we found multiple examples of MGEs inhibiting transformation through integrative disruption of genes encoding the competence machinery across many species, providing evidence of an ongoing "arms race." Reduced rates of transformation have also been observed in cells infected by MGEs that reduce the concentration of extracellular DNA through secretion of DNases. Simulations predicted that either mechanism of limiting transformation would benefit individual MGEs, but also that this tactic's effectiveness was limited by competition with other MGEs coinfecting the same cell. A further observed behaviour we hypothesised to reduce elimination by transformation was MGE activation when cells become competent. Our model predicted that this response was effective at counteracting transformation independently of competing MGEs. Therefore, this framework is able to explain both common properties of MGEs, and the seemingly paradoxical bacterial behaviours of transformation and cell-cell killing within clonally related populations, as the consequences of intragenomic conflict between self-replicating chromosomes and parasitic MGEs. The antagonistic nature of the different mechanisms of HDT over short timescales means their contribution to bacterial evolution is likely to be substantially greater than previously appreciated

Family Size and Turnover Rates among Several Classes of Small Non–Protein-Coding RNA Genes in Caenorhabditis Nematodes

It is important to understand the forces that shape the size and evolutionary histories of gene families. Here, we investigated the evolution of non–protein-coding RNA genes in the genomes of Caenorhabditis nematodes. We specifically focused on nested arrangements, that is, cases in which an RNA gene is entirely contained in an intron of another gene. Comparing these arrangements between species simplifies the inference of orthology and, therefore, of evolutionary fates of nested genes. Two distinct patterns are evident in the data. Genes encoding small nuclear RNAs (snRNAs) and transfer RNAs form large families, which have persisted since before the common ancestor of Metazoa. Yet, individual genes die relatively rapidly, with few orthologs having survived since the divergence of Caenorhabditis elegans and Caenorhabditis briggsae. In contrast, genes encoding small nucleolar RNAs (snoRNAs) are either single-copy or form small families. Individual snoRNAs turn over at a relatively slow rate—most C. elegans genes have clearly identifiable orthologs in C. briggsae. We also found that in Drosophila, genes from larger snRNA families die at a faster rate than their counterparts from single-gene families. These results suggest that a relationship between family size and the rate of gene turnover may be a general feature of genome evolution

Le FORUM, Vol. 39 No. 2

https://digitalcommons.library.umaine.edu/francoamericain_forum/1045/thumbnail.jp

Bibliographie raisonnée

La présente bibliographie, combinant ouvrages, actes de colloques et articles majeurs, vise d’abord à rappeler les principaux travaux et réflexions d’historiens se rapportant exclusivement à la sociabilité, au sens large. Elle détaille ensuite, notamment pour la France du Nord, les études consacrées à des thèmes plus spécifiques, traitant du XVIIIe siècle comme de l’époque contemporaine. En effet, de multiples formes de sociabilité s’adossent à des pratiques héritées, qu’elles soient simpleme..