Some relational structures with polynomial growth and their associated algebras II: Finite generation

The profile of a relational structure $R$ is the function $\varphi_R$ which counts for every integer $n$ the number, possibly infinite, $\varphi_R(n)$ of substructures of $R$ induced on the $n$-element subsets, isomorphic substructures being identified. If $\varphi_R$ takes only finite values, this is the Hilbert function of a graded algebra associated with $R$, the age algebra $A(R)$, introduced by P.~J.~Cameron. In a previous paper, we studied the relationship between the properties of a relational structure and those of their algebra, particularly when the relational structure $R$ admits a finite monomorphic decomposition. This setting still encompasses well-studied graded commutative algebras like invariant rings of finite permutation groups, or the rings of quasi-symmetric polynomials. In this paper, we investigate how far the well know algebraic properties of those rings extend to age algebras. The main result is a combinatorial characterization of when the age algebra is finitely generated. In the special case of tournaments, we show that the age algebra is finitely generated if and only if the profile is bounded. We explore the Cohen-Macaulay property in the special case of invariants of permutation groupoids. Finally, we exhibit sufficient conditions on the relational structure that make naturally the age algebra into a Hopf algebra.Comment: 27 pages; submitte

Periapical lesions after endodontic treatment

Background: Inflammation of a tooth can lead to periapical disease. The main objective of endodontic treatment is to clean and fill the root canal to heal the periapical inflammation. The treatment is not 100% successful, and knowledge of the lesions must be thorough. Aim: The aim of this study is to observe the dynamism of periapical lesions undergoing endodontic treatment. Materials and methods: For the realization of this integrative systematic review, we did a bibliographic search on the platform PUBMED. After applying the inclusion and exclusion criteria, we have obtained a corpus of 11 studies. Results: 5 studies (45,5%) were about composition of periapical lesions, 3 studies (27,3%) were about progression of periapical lesions, 2 studies (18,2%) were about the measures of periapical lesions, 1 study (9,1%) was about the relationship between treatment and periapical lesions. Discussion: Bacteria and microorganisms in the infected area have a strong association with the dynamism of a lesion. Studies show that bacteria are associated with several symptoms and pathogenicity. The probabilities made on the progression of the lesion is important to judge the endodontic treatment and to understand the possible causes of failures. Different techniques are used to quantify the microorganisms in the lesions and study their measurements. Conclusion: Improved techniques for the study and radiology of lesions will allow for more effective treatment and early diagnosis, thus avoiding pain and other strains on the patient and the practitioner

Inégalités salariales et bilinguisme au Québec et au Nouveau-Brunswick, 1970 à 2000

Cette étude réalisée avec les données censitaires mesure le lien entre le salaire, l’origine francophone ou anglophone et le bilinguisme français anglais entre 1970 et 2000 au Québec, la seule province du Canada où les francophones forment la majorité de la population, et au Nouveau-Brunswick, la seule des neuf autres provinces de ce pays où, quoique minoritaires, ils constituent une part plus que substantielle des effectifs provinciaux. La population à l’étude est composée d’hommes natifs pleinement et normalement intégrés au marché du travail. Cette population a été désignée par les économistes et les sociologues des années 1930 à 1970 comme population type pour l’analyse des inégalités salariales entre les francophones et les anglophones du Canada. Nous constatons la présence presque ininterrompue de 1970 à 2000 d’un lien historique entre le salaire, l’origine francophone ou anglophone et le bilinguisme au Nouveau-Brunswick. Également visible dans nos données sur le Québec de 1970, ce lien historique disparaît graduellement de 1970 à 1995, et en 1995, pour la première fois, nous observons que les salariés bilingues sont mieux rémunérés que les salariés unilingues au Québec et également mieux rémunérés, qu’ils soient issus de la communauté francophone ou anglophone. Ce résultat sur le Québec de 1995 est presque reproduit tel quel par nos données censitaires sur les salaires de l’an 2000.The objective of this article is to show, first, that the discourse on information technologies and high technology contributes to building a definition of high-skilled labour that obscures many aspects and fields of qualifications and that excludes many occupations in which we find highly skilled workers. For example, the definition of high-skilled labour does not take into account the different structures and dynamics of the work world, taking a more abstract approach to qualification-related problems, and disregards the social and cultural processes that contribute to defining high-skilled labour. We then use ethnographic data from field work in order to propose markers for an alternative definition of high-skilled labour, one that is more aligned with the actual contexts of the work world

Évolution des écarts entre les salaires des hommes francophones et anglophones âgés de 25 à 54 ans selon le bilinguisme au Nouveau-Brunswick de 1970 à 2000

Cette étude mesure l’évolution du lien entre le salaire, l’appartenance linguistique et le bilinguisme au sein des groupes francophone et anglo­­­phone du Nouveau-Brunswick, de 1970 à 2000. La population visée est formée de salariés masculins de 25 à 54 ans ayant fréquenté l’école durant au moins neuf ans et occupant un emploi régulier et stable dans les secteurs secondaire et tertiaire. Cette population forme une population type pour l’analyse de l’évolution des inégalités entre les francophones et les anglophones au Canada. Trois tendances ont été observées dans la présente étude. De 1970 à 2000, un lien histo­rique entre l’origine ethnolinguistique et le salaire se maintient au Nouveau-Brunwick. Il y a, de 1970 à 2000 toujours, un contraste entre un apport faible et non significatif du bilinguisme au salaire des anglophones et une forte rentabilité du bilinguisme pour les franco­phones. Par ailleurs, la proportion de francophones au sein de la main-d’oeuvre détenant un emploi régulier et stable a doublé de 1970 à 1990. Depuis cette date, cette proportion se situe à environ un tiers, soit l’équivalent du poids des francophones dans la population de la province.This paper examines the relation between salary, linguistic group and bilingualism among French-speaking and English-speaking New Brunswickers, and its evolution during the period from 1970 to 2000. The target population consisted of male salaried workers between 25 and 54 years of age, with at least nine years of schooling, who had regular, stable employment in secondary and tertiary industries. This population serves as a standard population for the purpose of analyzing inequalities between Francophones and Anglophones in Canada. Our research revealed three major trends. From 1970 to 2000, the historical correlation between ethnicity and salary persisted. During the same period, we found a marked contrast in the role of bilingualism on salary. Bilingualism made a minor and statistically insignificant contribution to the salaries of Anglophones, while it accounted for a major contribution to those of Francophones. Finally, the proportion of French-speaking workers among those who held regular, stable employment doubled between 1970 and 1990. Since that time, French-speaking workers represented approximately one-third of the labour force, consistent with the proportion of Francophones in the overall population of the province

Theoretical study of radiative electron attachment to CN, C2H, and C4H radicals

A first-principle theoretical approach to study the process of radiative electron attachment is developed and applied to the negative molecular ions CN$^-$, C$_4$H$^-$, and C$_2$H$^-$. Among these anions, the first two have already been observed in the interstellar space. Cross sections and rate coefficients for formation of these ions by radiative electron attachment to the corresponding neutral radicals are calculated. For completeness of the theoretical approach, two pathways for the process have been considered: (i) A direct pathway, in which the electron in collision with the molecule spontaneously emits a photon and forms a negative ion in one of the lowest vibrational levels, and (ii) an indirect, or two-step pathway, in which the electron is initially captured through non-Born-Oppenheimer coupling into a vibrationally resonant excited state of the anion, which then stabilizes by radiative decay. We develop a general model to describe the second pathway and show that its contribution to the formation of cosmic anions is small in comparison to the direct mechanism. The obtained rate coefficients at 30~K are $7\times 10^{-16}$cm$^3$/s for CN$^-$, $7\times 10^{-17}$cm$^3$/s for C$_2$H$^-$, and $2\times 10^{-16}$cm$^3$/s for C$_4$H$^-$. These rates weakly depend on temperature between 10K and 100 K. The validity of our calculations is verified by comparing the present theoretical results with data from recent photodetachment experiments

Influence of the Stereochemical Structure on The Physicochemical Properties of Polymers Prepared by Ring-Opening Polymerization of Chiral Heterocyclic Monomers

Physico-chemical properties of polymers prepared by ringopening polymerization of heterocyclic chiral monomers with different enantiomeric composition are compared. Two general kinds of behaviour were observed for products with a monosubstituted carbon in the chain: when the substituent group is not bulky the properties of polyenantiomers and their racemic mixture are very similar ; when the substituent is a bulky group, e. g. t-butyl, many of the properties (m.p., crystalline structure, solubility, etc.) are very different for the same polymers. The corresponding statistical stereocopolymers are amorphous. For polymers with disubstituted asymmetric carbon atoms the statistical stereocopolymers are crystalline and their melting behaviour varies with the enantiomeric purity. In some cases a strong dependence of the mechanical and biological properties on the enantiomeric purity of stereocopolymers is reported

A high resolution authigenic 10Be/9Be record of geomagnetic moment variations over the last 300 ka from sedimentary cores of the Portuguese margin.

A high resolution study of authigenic Be isotopes (10Be and 9Be) combined with continuous relative paleointensity records has been performed along the same marine sedimentary sequences from the Portuguese margin (N.E. Atlantic) covering the past 300 ka in order to assess relationships between geomagnetic moment variations and 10Be production rate variations. A carefull examination of the various ways of taking into account environmental disturbing effects on the authigenic 10Be concentration leads to the conclusion that the most reliable proxy of cosmonuclide production rates is presently the authigenic 10Be/9Be ratio. Eight intervals of significant authigenic 10Be/9Be enhancement evidence geomagnetic moment drops related to global paleomagnetic excursions, some being already admitted, others being proposed as new geomagnetic features. Since, contrarily to sedimentary magnetic remanence, the authigenic 10Be/9Be records dipole moment variations without significant acquisition delay, it provides better constraints on their timing. Comparison of 10Be/9Be and benthic δ18O records from the same cores suggests that dipole moment lows preferentially occured during or at the end of interglacial episodes, with a quasi-period of 100 ka

Characterization of Cs vapor cell coated with octadecyltrichlorosilane using coherent population trapping spectroscopy

We report the realization and characterization using coherent population trapping (CPT) spectroscopy of an octadecyltrichlorosilane (OTS)-coated centimeter-scale Cs vapor cell. The dual-structure of the resonance lineshape, with presence of a narrow structure line at the top of a Doppler-broadened structure, is clearly observed. The linewidth of the narrow resonance is compared to the linewidth of an evacuated Cs cell and of a buffer gas Cs cell of similar size. The Cs-OTS adsorption energy is measured to be (0.42 $\pm$ 0.03) eV, leading to a clock frequency shift rate of $2.7\times10^{-9}/$K in fractional unit. A hyperfine population lifetime, $T_1$, and a microwave coherence lifetime, $T_2$, of 1.6 and 0.5 ms are reported, corresponding to about 37 and 12 useful bounces, respectively. Atomic-motion induced Ramsey narrowing of dark resonances is observed in Cs-OTS cells by reducing the optical beam diameter. Ramsey CPT fringes are detected using a pulsed CPT interrogation scheme. Potential applications of the Cs-OTS cell to the development of a vapor cell atomic clock are discussed.Comment: 33 pages, 13 figure