The Late-Archean Magmatic Gold Event: Toward a Non-Uniformitarian Approach.

International audienceGold is exceptionally abundant at the end of Archean. Three main steps are recognized: (1) a late TTG event at the core of calderas, producing small porphyries and gold-rich VMS deposits; (2) a sanukitoïd event, producing alkaline and felsic subvolcanic plutons with large gold hydrothermal systems, and (3) a hydrothermal/structural event. A large part of the gold mineralization may be directly related to the unique geodynamic situation, including the first subduction with two generations of gold-enriched intrusions

Software Tool for Validation of Chromatographic Analytical Method

Tänapäeval toetuvad paljud valdkonnad erinevate ainete analüüsimiseks analüütilistele protseduuridele. Meditsiinivaldkonnas kasutatakse neid laborianalüüside tegemiseks. Farmaatsias kasutatakse neid ravimite aktiivsete komponentide ja nende koguste määramiseks ning defektide tuvastamiseks. Toitainetööstuses määratakse nende abil toitude ja nende koostisosade omadused. Analüütilist protseduuri võib vaadelda keemilise analüüsi algoritmina. Nende protseduuride suure populaarsuse tõttu on vajalik saada neid valideerida. Valideerimine tõestab, et analüütilise protseduuri poolt kirjeldatav keemiline analüüs on antud otstarbe jaoks mõistlik: et sellega saab vajalikku ühendit piisava täpsusega mõõta. Kahjuks teostatakse protseduuride valideerimine tänapäeval käsitsi analüütiliste keemikute poolt. Käsitsi valideerides võtab aga see palju aega ja on kerge teha vigu. Seega on vajalik analüütiliste keemikute töö hõlbustamiseks luua süsteeme, mis kindlustaks tulemuse korrektsust ja teeks kogu protsessi kergemaks. Tartu Ülikooli keemia instituut on tunnistanud selliste süsteemide vajalikust ja alustas ühe sellise süsteemi - ValChrom’i - arendust. See lõputöö hindab olemasolevate lahenduste tugevaid ja nõrki külgi ning räägib analüütiliste protseduuride valideerimiseks mõeldud veebirakenduse ValChrom implementatsioonist.Many industries rely on analytical procedures to analyze various substances. In the medical field they are used to perform laboratory analyzes. In the pharmaceutical industry they are used to determine and quantify the active component of a drug product as well as impurities. In the food industry they are used to identify the properties of foods and their ingredients. An analytical procedure can be assimilable to the algorithm of a chemical analysis. Due to their widespread use, analytical procedures must be validated. The validation process will prove that the chemical analysis described by the analytical procedure is judicious and fit for its intended use case. That is, the chemical analysis can accurately measure the compound it is supposed to measure. Sadly, that validation process, currently, is performed manually by analytical chemists. The completion of analytical procedure validation manually is tedious and potentially error-prone. Therefore, accessible systems that can assist analytical chemists during analytical procedure validation should be made available to them. These systems will not only ensure the consistency of the result but also alleviate the workload of analytical chemists. The Department of Chemistry of the University of Tartu has acknowledged the need of such systems and launched the implementation of one named ValChrom. This thesis highlights the implementation details of ValChrom – a web-based application for analytical procedure validation, after evaluating the strengths and shortcomings of existing similar software solutions

Acquisition of French Liaison and Related Child Errors

Although French liaison is a major topic in the fields of adult French phonology and sociolinguistics, its acquisition remains a terra incognita. Moreover, very frequent liaison consonant substitutions ("les- n-ours" instead of the adult form "les ours" with a /z/ liaison) or insertions ("papa-n-ours" instead of "papa ours") are well-known stereotypes of the French "babytalk", but their relationship with the acquisition of liaison has never been considered. Three kinds of data addressing these issues are presented. First, 300 such errors in the speech of a girl (from 2;0 to 3;6) during daily interactions will be analyzed. They suggest that /n/ is the most intrusive liaison consonant (compared with /z/ and /t/). Second, an experimentation has been carried out with 4-year old children (N=24) with the purpose of eliciting errors in words with obligatory liaisons. The results provide confirmation that /n/ is the most intrusive liaison consonant and suggest that some children are prone to use the liaison consonant they have just heard : they say more ofen "un-z-ours" (with a /z/ liaison instead of the adult /n/) after they have heard "des ours" with an adult-like /z/ liaison. Third, an experiment with three age groups [age means: 3;5 (N=15), 4;6 (N=24), 5;8 (N=15)] investigates whether implicit knowledge about probabilistic phonotactic constraints is used in segmenting ambiguous "determiner-noun" sequences. For example, subjects are hearing "determiner + non-word" sequences including a /n/ or a /z/ consonant, whose lexical and syllabic status is ambiguous : in such a sequence as "un (n)apil", one cannot hear whether /n/ is the coda liaison consonant of "un" (un apil), or whether it is the consonantal onset of the non word (un napil). Subjects are then asked to replace the singular determiner "un" with the plural determiner "des" (and vice versa when "des" + non-word sequences are presented). Responses like [dezapil] suggest that they consider /n/ to be a liaison consonant. Responses like [denapil] suggest that they view /n/ as the initial onset of the non-word "napil". Results show that responses of the youngest group do not fit phonotactic constraints (in French, /n/ is more frequent than /z/ as a word initial consonant and /z/ more frequent than /n/ as a liaison consonant) . The discussion addresses two issues : (1) What is the lexical status of liaison in the phonological representation of young children ? (2) If knowlegdge about phonotactic constraints is not available before the age of 4, how could we explain that /n/ is the most intrusive liaison consonant as early as the age of 2

Liaison acquisition, word segmentation and construction in French: A usage based account

International audienceIn the linguistic field, liaison in French is interpreted as an indicator of interactions between the various levels of language organization. The current study examines the same issue while adopting a developmental perspective. Five experiments involving children aged 2-6 years provide evidence for a developmental scenario which interrelates a number of different issues: the acquisition of phonological alternations, the segmentation of new words, the long-term stabilization of the word form in the lexicon, and the formation of item-based constructions. According to this scenario, children favour the presence of initial CV syllables when segmenting stored chunks of speech of the type word1-liaison-word2 (les arbres 'the trees' is segmented as /le/ + /zarbr/). They cope with the variation of the liaison in the input by memorizing multiple exemplars of the same word2 (/zarbr/, /narbr/). They learn the correct relations between the word1s and the word2 exemplars through exposure to the well-formed sequence (un + /narbr/, deux + /zarbr/). They generalize the relation between a word1 and a class of word2 exemplars beginning with a specific liaison consonant by integrating this information into an item-based schema (e.g. un + /nX/, deux + /zX/). This model is based on the idea that the segmentation of new words and the development of syntactic schemas are two aspects of the same process

Retrieval or nonretrieval strategies in mental arithmetic? An operand recognition paradigm

According to LeFevre, Sadesky, and Bisanz (1996), averaging solution latencies in order to study individuals' arithmetic strategies can result in misleading conclusions. Therefore, in addition to classical chronometric data, they collected verbal reports and challenged the assumption that adults rely systematically on retrieval of arithmetic facts from memory to solve simple addition problems. However, Kirk and Ashcraft (2001) questioned the validity of such a methodology and concluded that a more appropriate method has to be found. Thus, we developed an operand recognition paradigm that does not rely on verbal reports or on solution latencies. In accordance with LeFevre et al., we show in a first experiment that adults resort to nonretrieval strategies to solve addition problems involvingmedium numbers. However, in a second experiment, we show that high-skilled individuals can solve the same problems using a retrieval strategy. The benefits of our paradigm to the study of arithmetic strategies are discusse

Usage-based account of the acquisition of liaison: evidence from sensitivity to plural / singular orientation of nouns

International audienceThis study investigates whether the production and the recognition of liaison sequences in children depend on the singular/plural orientation of nouns. Certain nouns occur more frequently in the plural (e.g., arbre "tree") whereas others are found more often in the singular (e.g., arc-en-ciel "rainbow"). In the input, children more frequently encounter these plural-oriented nouns after determiners which indicate plurality (e.g., les, des, "the", deux, "two", etc.) and which are often associated with a /z/ liaison [døzarbr],"two trees". In experiment 1, 122 children (aged from 3;2 to 6;3) were asked to produce nominal phrases with either /z/ liaisons (i.e., in plural contexts like deux ours [døzurs],"two bears") or with /n/ liaisons (i.e., in singular contexts like un ours [oenurs],"one bear"). We found correlations between the plural-orientation of the nouns and (1) the probability that they will be preceded by an incorrect /z/ liaison in singular contexts (2) the probability that they will be preceded by a correct /z/ liaison in the plural context. This result was however restricted to the younger children. In experiment 2, 20 children (aged from 5;5 to 6;3) were asked to monitor target words in auditorily presented sentences. The results showed shorter responses times for singular-oriented nouns when preceded by singular determiners than when preceded by plural determiners. Conversely, plural-oriented nouns were responded to faster when preceded by a plural determiner than by a singular determiner. Results are discussed within the framework of a two-stage model of liaison acquisition recently proposed by Chevrot, Chabanal and Dugua (2007) and Chevrot, Dugua and Fayol (2009)

Pembuatan Asam Oksalat dari Sekam Padi Menggunakan Proses Hidrolisis

Produksi padi untuk memenuhi kebutuhan semakin meningkat setiap tahun yang menyebabkan banyaknya limbah sekam padi yang dihasilkan. Sekam padi pada penelitian ini mengandung selulosa 26,93% dan lignin 14,07%. Tujuan penelitian adalah untuk menemukan konsentrasi NaOH dan waktu lama pengadukan yang terbaik pada pembuatan asam oksalat dari sekam padi, serta mencari kadar asam oksalat yang dihasilkan dari sekam padi. Variabel peubah dalam penelitian adalah beberapa konsentrasi NaOH yaitu 2N, 3N, 4N, 5N, 6N serta waktu lama pengadukan yaitu 30 menit, 45 menit, 60 menit, 75 menit serta 90 menit. Penelitian ini dimulai dengan proses hidrolisis menggunakan NaOH, pengendapan menggunakan CaCl2, dilanjutkan pengasaman menggunakan H2SO4, lalu dilakukan analisa kadar menggunakan metode titrasi permanganometri. Setelah itu, hasil penelitian dilakukan proses optimasi dengan Response Surafce Methodology menggunakan Minitab. Konsentrasi NaOH dan waktu pengadukan terbaik yaitu pada konsentrasi NaOH 5N dan waktu lama pengadukan 75 menit dengan kadar asam oksalat yang diperoleh sebesar 11,661%

Le nombre, sa genèse et son utilisation par l’enfant et l’adulte

Inexistent

The Use of the Operand-Recognition Paradigm for the Study of Mental Addition in Older Adults

Objectives. Determining how individuals solve arithmetic problems is crucial for our understanding of human cognitive architecture. Elderly adults are supposed to use memory retrieval more often than younger ones. However, they might backup their retrieval by reconstructive strategies. In order to investigate this issue, we used the operand-recognition paradigm, which capitalizes on the fact that algorithmic procedures degrade the memory traces of the operands. Method. Twenty-three older adults (M = 70.4) and 23 younger adults (M = 20.0) solved easy, difficult, and medium-difficulty addition and comparison problems and were then presented with a recognition task of the operands. Results. When one-digit numbers with sums larger than 10 were involved (medium-difficulty problem), it was more difficult for younger adults to recognize the operands after addition than comparison. In contrast, in older adults, recognition times of the operands were the same after addition and comparison. Discussion. Older adults, in contrast with younger adults, are able to retrieve the results of addition problems of medium difficulty. Contrary to what was suggested, older participants do not seem to resort to backup strategies for such problems. Finally, older adults' reliance on the more efficient retrieval strategy allowed them to catch up to younger adults in terms of solution time