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Sample records for etude rimed rayonnements

  1. Learning Words with Common Rimes.

    ERIC Educational Resources Information Center

    Dwyer, Edward J.

    An extensive research review by M. Adams (1990) led her to the conclusion that providing instruction and reinforcement in learning common rimes is highly beneficial in fostering growth in learning to read. While substantial amounts of reading, either independent or with partners, is critical in learning words with common rimes, focused study is…

  2. Rhyme, rime, and the onset of reading.

    PubMed

    Kirtley, C; Bryant, P; MacLean, M; Bradley, L

    1989-10-01

    There is recent evidence that children naturally divide syllables into the opening consonant or consonant cluster (the onset) and the rest of the syllable (the rime). This suggests an explanation for the fact that preschool children are sensitive to rhyme, but often find tasks in which they have to isolate single phonemes extremely difficult. Words which rhyme share a common rime and thus can be categorized on that speech unit. Single phonemes on the other hand may only be part of one of these speech units. This analysis leads to some clear predictions. Young children, even children not yet able to read, should manage to categorize words on the basis of a single phoneme when the phoneme coincides with the word's onset ("cat," "cup") but not when it is only part of the rime ("cat," "pit"). They should find it easier to work out that two monosyllabic words have a common vowel which is not shared by another word when all three words end with the same consonant ("lip," "hop," "tip") but the odd word has a different rime than when the three words all start with the same consonant ("cap," "can," "cot") and thus all share the same onset. The hypothesis also suggests that children should be aware of single phonemes when these coincide with the onset before they learn to read. We tested these predictions in two studies of children aged 5, 6, and 7 years. The results clearly support these predictions.

  3. Growth of ice particle mass and projected area during riming

    NASA Astrophysics Data System (ADS)

    Erfani, Ehsan; Mitchell, David L.

    2017-01-01

    There is a long-standing challenge in cloud and climate models to simulate the process of ice particle riming realistically, partly due to the unrealistic parameterization of the growth of ice particle mass (m) and projected area (A) during riming. This study addresses this problem, utilizing ground-based measurements of m and ice particle maximum dimension (D) as well as theory to formulate simple expressions describing the dependence of m and A on riming. It was observed that β in the m - D power law m = α Dβ appears independent of riming during the phase 1 (before the formation of graupel), with α accounting for the ice particle mass increase due to riming. This semi-empirical approach accounts for the degree of riming and renders a gradual and smooth ice particle growth process from unrimed ice particles to graupel, and thus avoids discontinuities in m and A during accretional growth. Once the graupel with quasi-spherical shape forms, D increases with an increase in m and A (phase 2 of riming). The treatment for riming is explicit, and includes the parameterization of the ice crystal-cloud droplet collision efficiency (Ec) for hexagonal columns and plates using hydrodynamic theory. In particular, Ec for cloud droplet diameters less than 10 µm are estimated, and under some conditions observed in mixed-phase clouds, these droplets can account for roughly half of the mass growth rate from riming. These physically meaningful yet simple methods can be used in models to improve the riming process.

  4. Rime Mushrooms - Extreme Rime Ice Buildup on Mountain Summits of Southern Patagonia

    NASA Astrophysics Data System (ADS)

    Whiteman, C. D.

    2015-12-01

    The Southern Patagonian Andes are known among mountain climbers for a meteorological phenomenon that occurs there but is unknown in many other mountain areas. The phenomenon is the buildup of rime ice in large bulbous or mushroom-shaped accretions on the windward side of projecting mountain summits, ridges and exposed near-vertical rock faces. These "ice mushrooms" have never been investigated scientifically. This talk will introduce the audience to ice mushrooms, describe where they are found, consider the meteorological factors leading to their formation, and illustrate how they are negotiated by mountain climbers using photographs and descriptions from Southern Patagonia.

  5. Folds and Etudes

    ERIC Educational Resources Information Center

    Bean, Robert

    2007-01-01

    In this article, the author talks about "Folds" and "Etudes" which are images derived from anonymous typing exercises that he found in a used copy of "Touch Typing Made Simple". "Etudes" refers to the musical tradition of studies for a solo instrument, which is a typewriter. Typing exercises are repetitive attempts to type words and phrases…

  6. Insights into riming and aggregation processes as revealed by aircraft, radar, and disdrometer observations for a 27 April 2011 widespread precipitation event: Insights into Riming and Aggregation

    SciTech Connect

    Giangrande, Scott E.; Toto, Tami; Bansemer, Aaron; Kumjian, Matthew R.; Mishra, Subhashree

    2016-05-19

    Our study presents aircraft spiral ascent and descent observations intercepting a transition to riming processes during widespread stratiform precipitation. The sequence is documented using collocated scanning and profiling radar, including longer-wavelength dual polarization measurements and shorter-wavelength Doppler spectra. Riming regions are supported using aircraft measurements recording elevated liquid water concentrations, spherical particle shapes, and saturation with respect to water. Profiling cloud radar observations indicate riming regions during the event as having increasing particle fall speeds, rapid time-height changes, and bimodalities in Doppler spectra. These particular riming signatures are coupled to scanning dual polarization radar observations of higher differential reflectivity (ZDR) aloft. Moreover, reduced melting layer enhancements and delayed radar bright-band signatures in the column are also observed during riming periods, most notably with the profiling radar observations. The bimodal cloud radar Doppler spectra captured near riming zones indicate two time-height spectral ice peaks, one rimed particle peak, and one peak associated with pristine ice needle generation and/or growth between -4°C and -7°C also sampled by aircraft probes. We observe this pristine needle population near the rimed particle region which gives a partial explanation for the enhanced ZDR. The riming signatures aloft and radar measurements within the melting level are weakly lag correlated (r~0.6) with smaller median drop sizes at the surface, as compared with later times when aggregation of larger particle sizes was believed dominant.

  7. Insights into riming and aggregation processes as revealed by aircraft, radar, and disdrometer observations for a 27 April 2011 widespread precipitation event: Insights into Riming and Aggregation

    DOE PAGES

    Giangrande, Scott E.; Toto, Tami; Bansemer, Aaron; ...

    2016-05-19

    Our study presents aircraft spiral ascent and descent observations intercepting a transition to riming processes during widespread stratiform precipitation. The sequence is documented using collocated scanning and profiling radar, including longer-wavelength dual polarization measurements and shorter-wavelength Doppler spectra. Riming regions are supported using aircraft measurements recording elevated liquid water concentrations, spherical particle shapes, and saturation with respect to water. Profiling cloud radar observations indicate riming regions during the event as having increasing particle fall speeds, rapid time-height changes, and bimodalities in Doppler spectra. These particular riming signatures are coupled to scanning dual polarization radar observations of higher differential reflectivity (ZDR)more » aloft. Moreover, reduced melting layer enhancements and delayed radar bright-band signatures in the column are also observed during riming periods, most notably with the profiling radar observations. The bimodal cloud radar Doppler spectra captured near riming zones indicate two time-height spectral ice peaks, one rimed particle peak, and one peak associated with pristine ice needle generation and/or growth between -4°C and -7°C also sampled by aircraft probes. We observe this pristine needle population near the rimed particle region which gives a partial explanation for the enhanced ZDR. The riming signatures aloft and radar measurements within the melting level are weakly lag correlated (r~0.6) with smaller median drop sizes at the surface, as compared with later times when aggregation of larger particle sizes was believed dominant.« less

  8. Insights into riming and aggregation processes as revealed by aircraft, radar, and disdrometer observations for a 27 April 2011 widespread precipitation event: Insights into Riming and Aggregation

    SciTech Connect

    Giangrande, Scott E.; Toto, Tami; Bansemer, Aaron; Kumjian, Matthew R.; Mishra, Subhashree

    2016-05-19

    Our study presents aircraft spiral ascent and descent observations intercepting a transition to riming processes during widespread stratiform precipitation. The sequence is documented using collocated scanning and profiling radar, including longer-wavelength dual polarization measurements and shorter-wavelength Doppler spectra. Riming regions are supported using aircraft measurements recording elevated liquid water concentrations, spherical particle shapes, and saturation with respect to water. Profiling cloud radar observations indicate riming regions during the event as having increasing particle fall speeds, rapid time-height changes, and bimodalities in Doppler spectra. These particular riming signatures are coupled to scanning dual polarization radar observations of higher differential reflectivity (ZDR) aloft. Moreover, reduced melting layer enhancements and delayed radar bright-band signatures in the column are also observed during riming periods, most notably with the profiling radar observations. The bimodal cloud radar Doppler spectra captured near riming zones indicate two time-height spectral ice peaks, one rimed particle peak, and one peak associated with pristine ice needle generation and/or growth between -4°C and -7°C also sampled by aircraft probes. We observe this pristine needle population near the rimed particle region which gives a partial explanation for the enhanced ZDR. The riming signatures aloft and radar measurements within the melting level are weakly lag correlated (r~0.6) with smaller median drop sizes at the surface, as compared with later times when aggregation of larger particle sizes was believed dominant.

  9. A Longitudinal Study of the Effects of Word Frequency and Rime-Neighborhood Size on Beginning Readers' Rime Reading Accuracy in Words and Nonwords.

    ERIC Educational Resources Information Center

    Calhoon, J. Anne; Leslie, Lauren

    2002-01-01

    Finds in year 1, children showed effects of neighborhood size in high frequency words read in stories and in low frequency words read in lists and stories; in year 2, rimes from large neighborhoods were read more accurately than rimes from other neighborhoods; and by year 3, effects on low-frequency words continued, but not for high-frequency…

  10. RIME proteomics of estrogen and progesterone receptors in breast cancer

    PubMed Central

    D’Santos, Clive; Taylor, Christopher; Carroll, Jason S.; Mohammed, Hisham

    2015-01-01

    Nuclear receptors play an important role in transcriptional regulation of diverse cellular processes and is also relevant in diseases such as cancer. In breast cancer, the nuclear receptors – estrogen receptor (ER) and progesterone receptor (PR) are classical markers of the disease and are used to classify breast cancer subtypes. Using a recently developed affinity purification MS technique (RIME) [1], we investigate the protein interactors of ER and PR in breast cancer cell lines upon stimulation by the ligands – estrogen and progesterone. The data is deposited at proteomeXchange (PXD002104) and is part of a publication [2] that explains the link between the two nuclear receptors and potential consequences of this in breast cancer. In this manuscript, we describe the methodology used and provide details on experimental procedures, analysis methods and analysis of raw data. The purpose of this article is to enable reproducibility of the data and provide technical recommendations on performing RIME in hormonal contexts. PMID:26543891

  11. Charge transfer during individual collisions in ice growing by riming

    NASA Technical Reports Server (NTRS)

    Avila, Eldo E.; Caranti, Giorgio M.

    1991-01-01

    The charging of a target by riming in the wind was studied in the temperature range of (-10, -18 C). For each temperature, charge transfers of both signs are observed and, according to the environmental conditions, one of them prevails. The charge is more positive as the liquid water concentration is increased at any particular temperature. It is found that even at the low impact velocities used (5 m/s) there is abundant evidence of fragmentation following the collision.

  12. Etude de la dynamique des porteurs dans des nanofils de silicium par spectroscopie terahertz

    NASA Astrophysics Data System (ADS)

    Beaudoin, Alexandre

    Ce memoire presente une etude des proprietes de conduction electrique et de la dynamique temporelle des porteurs de charges dans des nanofils de silicium sondes par rayonnement terahertz. Les cas de nanofils de silicium non intentionnellement dopes et dopes type n sont compares pour differentes configurations du montage experimental. Les mesures de spectroscopie terahertz en transmission montre qu'il est possible de detecter la presence de dopants dans les nanofils via leur absorption du rayonnement terahertz (˜ 1--12 meV). Les difficultes de modelisation de la transmission d'une impulsion electromagnetique dans un systeme de nanofils sont egalement discutees. La detection differentielle, une modification au systeme de spectroscopie terahertz, est testee et ses performances sont comparees au montage de caracterisation standard. Les instructions et des recommendations pour la mise en place de ce type de mesure sont incluses. Les resultats d'une experience de pompe optique-sonde terahertz sont egalement presentes. Dans cette experience, les porteurs de charge temporairement crees suite a l'absorption de la pompe optique (lambda ˜ 800 nm) dans les nanofils (les photoporteurs) s'ajoutent aux porteurs initialement presents et augmentent done l'absorption du rayonnement terahertz. Premierement, l'anisotropie de l'absorption terahertz et de la pompe optique par les nanofils est demontree. Deuxiemement, le temps de recombinaison des photoporteurs est etudie en fonction du nombre de photoporteurs injectes. Une hypothese expliquant les comportements observes pour les nanofils non-dopes et dopes-n est presentee. Troisiemement, la photoconductivite est extraite pour les nanofils non-dopes et dopes-n sur une plage de 0.5 a 2 THz. Un lissage sur la photoconductivite permet d'estimer le nombre de dopants dans les nanofils dopes-n. Mots-cles: nanofil, silicium, terahertz, conductivite, spectroscopie, photoconductivite.

  13. Quantifying the effect of riming on snowfall using ground-based observations

    NASA Astrophysics Data System (ADS)

    Moisseev, Dmitri; von Lerber, Annakaisa; Tiira, Jussi

    2017-04-01

    Ground-based observations of ice particle size distribution and ensemble mean density are used to quantify the effect of riming on snowfall. The rime mass fraction is derived from these measurements by following the approach that is used in a single ice-phase category microphysical scheme proposed for the use in numerical weather prediction models. One of the characteristics of the proposed scheme is that the prefactor of a power law relation that links mass and size of ice particles is determined by the rime mass fraction, while the exponent does not change. To derive the rime mass fraction, a mass-dimensional relation representative of unrimed snow is also determined. To check the validity of the proposed retrieval method, the derived rime mass fraction is converted to the effective liquid water path that is compared to microwave radiometer observations. Since dual-polarization radar observations are often used to detect riming, the impact of riming on dual-polarization radar variables is studied for differential reflectivity measurements. It is shown that the relation between rime mass fraction and differential reflectivity is ambiguous, other factors such as change in median volume diameter need also be considered. Given the current interest on sensitivity of precipitation to aerosol pollution, which could inhibit riming, the importance of riming for surface snow accumulation is investigated. It is found that riming is responsible for 5% to 40% of snowfall mass. The study is based on data collected at the University of Helsinki field station in Hyytiälä during U.S. Department of Energy Biogenic Aerosols Effects on Clouds and Climate (BAECC) field campaign and the winter 2014/2015. In total 22 winter storms were analyzed, and detailed analysis of two events is presented to illustrate the study.

  14. The Role of Phoneme and Onset-Rime Awareness in Second Language Reading Acquisition

    ERIC Educational Resources Information Center

    Haigh, Corinne A.; Savage, Robert; Erdos, Caroline; Genesee, Fred

    2011-01-01

    This study investigated the link between phoneme and onset-rime awareness and reading outcomes in children learning to read in a second language (L2). Closely matched phoneme and onset-rime awareness tasks were administered in English and French in the spring of kindergarten to English-dominant children in French immersion programmes (n=98).…

  15. The Role of Phoneme and Onset-Rime Awareness in Second Language Reading Acquisition

    ERIC Educational Resources Information Center

    Haigh, Corinne A.; Savage, Robert; Erdos, Caroline; Genesee, Fred

    2011-01-01

    This study investigated the link between phoneme and onset-rime awareness and reading outcomes in children learning to read in a second language (L2). Closely matched phoneme and onset-rime awareness tasks were administered in English and French in the spring of kindergarten to English-dominant children in French immersion programmes (n=98).…

  16. Analysis of Phonemes, Graphemes, Onset-Rimes, and Words with Braille-Learning Children

    ERIC Educational Resources Information Center

    Crawford, Shauna; Elliott, Robert T.

    2007-01-01

    Six primary school-aged braille students were taught to name 4 to 10 braille letters as phonemes and another 4 to 10 braille letters as graphemes (Study 1). They were then taught to name 10 braille words as onset-rimes and another 10 braille words as whole words (Study 2). Instruction in phonemes and onset rimes resulted in fewer trials and a…

  17. Getting the "ig" in Pig: Helping Children Discover Onset and Rime.

    ERIC Educational Resources Information Center

    Rosen, Michelle

    This phonics lesson offers a clear instructional format for teaching onset and rime. The "ig" rime is demonstrated through the use of literature, independent and cooperative learning, critical thinking, and hands-on activities. Instruction is conducted in both an explicit and implicit manner. During two to three 40-minute sessions,…

  18. Subsyllabic Units in Computerized Reading Instruction: Onset-Rime vs. Postvowel Segmentation.

    ERIC Educational Resources Information Center

    Wise, Barbara W.; And Others

    1990-01-01

    Three experiments with 20 first grade students concerned possible benefits of onset-rime segmentation for reading instruction of children. In all experiments, onset-rime segmentation proved more helpful than postvowel segmentation in short-term learning of single words composed of 4 letters representing 3 and 4 phonemes. (RH)

  19. The special role of rimes in the description, use, and acquisition of English orthography.

    PubMed

    Treiman, R; Mullennix, J; Bijeljac-Babic, R; Richmond-Welty, E D

    1995-06-01

    The links between spellings and sounds in a large set of English words with consonant-vowel-consonant phonological structure were examined. orthographic rimes, or units consisting of a vowel grapheme and a final consonant grapheme, had more stable pronunciations than either individual vowels or initial consonant-plus-vowel units. In 2 large-scale studies of word pronunciation, the consistency of pronunciation of the orthographic rime accounted for variance in latencies and errors beyond that contributed by the consistency of pronunciation of the individual graphemes and by other factors. In 3 experiments, as well, children and adults made more errors on words with less consistently pronounced orthographic rimes than on words with more consistently pronounced orthographic rimes. Relations between spellings and sounds in the simple monomorphemic words of English are more predictable when the level of onsets and rimes is taken into account than when only graphemes and phonemes are considered.

  20. Investigation of riming within mixed-phase stratiform clouds using Weather Research and Forecasting (WRF) model

    NASA Astrophysics Data System (ADS)

    Hou, Tuanjie; Lei, Hengchi; Yang, Jiefan; Hu, Zhaoxia; Feng, Qiujuan

    2016-09-01

    In this study, we investigated stratiform precipitation associated with an upper-level westerly trough and a cold front over northern China between 30 Apr. and 1 May 2009. We employed the Weather Research and Forecasting (WRF) model (version 3.4.1) to perform high-resolution numerical simulations of rainfall. We also conducted simulations with two microphysics schemes and sensitivity experiments without riming of snow and changing cloud droplet number concentrations (CDNCs) to determine the effect of snow riming on cloud structure and precipitation. Then we compared our results with CloudSat, Doppler radar and rain gauge observations. The comparison with the Doppler radar observations suggested that the WRF model was quite successful in capturing the timing and location of the stratiform precipitation region. Further comparisons with the CloudSat retrievals suggested that both microphysics schemes overestimated ice and liquid water contents. The sensitivity experiments without riming of snow suggested that the presence or absence of riming significantly influenced the precipitation distribution, but only slightly affected total accumulated precipitation. Without riming of snow, the changes of updrafts from the two microphysics schemes were different due to a different consideration of ice particle capacitance and latent heat effect of riming on deposition. While sensitivity experiments with three different CDNC values of 100, 250 and 1000 cm- 3 suggested variations in snow riming rates, changing CDNC had little impact on precipitation.

  1. The biopsychosocial spiritual model applied to the treatment of women with breast cancer, through RIME intervention (relaxation, mental images, spirituality).

    PubMed

    Elias, Ana Catarina Araújo; Ricci, Marcos Desidério; Rodriguez, Lórgio Henrique Diaz; Pinto, Stela Duarte; Giglio, Joel Sales; Baracat, Edmund Chada

    2015-02-01

    This postdoctoral study on the application of the RIME intervention in women that had undergone mastectomy and were in treatment, aimed to promote psychospiritual and social transformations to improve the quality of life, self-esteem and hope. A total of 28 women participated and were randomized into two groups. Brief Psychotherapy (PB) (average of six sessions) was administered in the Control Group, and RIME (three sessions) and BP (average of five sessions) were applied in the RIME Group. The quantitative results indicated a significant improvement (38.3%) in the Perception of Quality of Life after RIME according to the WHOQOL, compared both to the BP of the Control Group (12.5%), and the BP of the RIME Group (16.2%). There was a significant improvement in Self-esteem (Rosenberg) after RIME (14.6%) compared to the BP of the Control Group (worsened 35.9%), and the BP of the RIME Group (8.3%). The improvement in well-being, considering the focus worked on (Visual Analog Scale), was significant in the RIME Group (bad to good), as well as in the Control Group (unpleasant to good). The qualitative results indicated that RIME promotes creative transformations in the intrapsychic and interpersonal dimensions, so that new meanings and/or new attitudes emerge into the consciousness. It was observed that RIME has more strength of psychic structure, ego strengthening and provides a faster transformation that BP, therefore it can be indicated for crisis treatment in the hospital environment.

  2. The Radar for Icy Moon Exploration (RIME) on the JUICE Mission

    NASA Astrophysics Data System (ADS)

    Bruzzone, L.; Plaut, J.; Alberti, G.; Blankenship, D. D.; Bovolo, F.; Campbell, B. A.; Castelletti, D.; Gim, Y.; Ilisei, A. M.; Kofman, W. W.; Komatsu, G.; McKinnon, W. B.; Mitri, G.; Moussessian, A.; Notarnicola, C.; Orosei, R.; Patterson, G. W.; Pettinelli, E.; Plettemeier, D.

    2015-12-01

    The Radar for Icy Moon Exploration (RIME) is one of the main instruments included in the JUpiter ICy moons Explorer (JUICE) ESA mission. It is a radar sounder designed for studying the subsurface geology and geophysics of Galilean icy moons (i.e., Ganymede, Europa and Callisto) and for detecting possible subsurface water. RIME is designed for penetration of the icy moons up to a depth of 9 km. Two main operation scenarios are foreseen for RIME: i) flyby observations of Europa, Ganymede and Callisto (from a distance of 1000 km to the closest approach of about 400 km); and ii) circular orbital observations around Ganymede at 500 km of altitude. According to these scenarios, RIME is designed to explore the icy shell of the Galilean icy satellites by characterizing the wide range of compositional, thermal, and structural variation found in the subsurface of these moons. RIME observations will profile the ice shells of the Galilean icy satellites with specific focus on Ganymede given the circular orbital phase. The acquired measures will provide geological context on hemispheric (thousands of km), regional (hundreds of km with multiple overlaps), and targeted (tens of km) scales appropriate for a variety of hypothesis tests. RIME will operate in a single frequency band, centred at 9 MHz. The frequency was selected as the result of extensive study of penetration capabilities, surface roughness of the moons, Jovian radio noise, antenna accommodation, and system design. The 9 MHz frequency provides penetration capabilities and mitigation of surface scattering (which can cause signal loss and clutter issues), at the expense of mapping coverage, as it is likely to obtain high SNR observations only on the anti-Jovian side of the target moons. The RIME antenna is a 16 m dipole. The chirp pulse bandwidth is up to 3 MHz, which provides vertical resolution of about 50 m in ice after side lobe weighting. RIME will also operate with 1 MHz bandwidth to reduce data volume when

  3. Microscopic observations of riming on an ice surface using high speed video

    NASA Astrophysics Data System (ADS)

    Emersic, C.; Connolly, P. J.

    2017-03-01

    Microscopic droplet riming events on an ice surface have been observed using high speed video. Observations included greater propensity for droplet spreading at temperatures higher than - 15 °C on flatter ice surfaces, and subsequently, the formation of growing rime spires into the flow, allowing glancing droplet collisions and more spherical freezing of smaller droplets. Insight into differences between laboratory observations of the Hallett-Mossop process is offered, relating to the nature of droplet spreading associated with the structure of the rimer surface prior to impact. Observations of a difference between air speed and resulting droplet impact speed on an ice surface may affect interpretations of riming laboratory studies, and may explain recent observations of a high secondary ice production rate in supercooled layer clouds.

  4. Syllable and rime patterns for teaching reading: Analysis of a frequency-based vocabulary of 17,602 words.

    PubMed

    Stanback, M L

    1992-12-01

    A frequency-based vocabulary of 17,602 words was compiled and analyzed in order to group words with recurring syllable and rime patterns for teaching reading. The role of the rime unit (e.g.,ite inkite andinvite) in determining vowel pronunciation was central to the analysis because of the difficulty that the ambiguity of English vowel spelling presents to children who do not learn to read words easily. Vowel pronunciation in each orthographic rime was examined, both for its consistency in all words in which the rime occurs and for regularity, defined as conformity to the most frequent pronunciation for each vowel spelling in each of six orthographic syllable types.Of the 824 different orthographic rimes, 616 occur in rime families as the building blocks of almost all the 43,041 syllables of the words. These rimes account for a striking amount of patterning in the orthography: 436 are both regular and consistent in pronunciation (except where a single exception word occurs); another 55 are consistent but not regular. Of the remaining 125, only 86 have less than a 90 percent level of consistency. The high order of congruence of orthographic and phonological rimes suggests their usefulness as units for teaching reading.

  5. The ingi and RIME non-LTR retrotransposons are not randomly distributed in the genome of Trypanosoma brucei.

    PubMed

    Bringaud, Frédéric; Biteau, Nicolas; Zuiderwijk, Eduard; Berriman, Matthew; El-Sayed, Najib M; Ghedin, Elodie; Melville, Sara E; Hall, Neil; Baltz, Théo

    2004-03-01

    The ingi (long and autonomous) and RIME (short and nonautonomous) non--long-terminal repeat retrotransposons are the most abundant mobile elements characterized to date in the genome of the African trypanosome Trypanosoma brucei. These retrotransposons were thought to be randomly distributed, but a detailed and comprehensive analysis of their genomic distribution had not been performed until now. To address this question, we analyzed the ingi/RIME sequences and flanking sequences from the ongoing T. brucei genome sequencing project (TREU927/4 strain). Among the 81 ingi/RIME elements analyzed, 60% are complete, and 7% of the ingi elements (approximately 15 copies per haploid genome) appear to encode for their own transposition. The size of the direct repeat flanking the ingi/RIME retrotransposons is conserved (i.e., 12-bp), and a strong 11-bp consensus pattern precedes the 5'-direct repeat. The presence of a consensus pattern upstream of the retroelements was confirmed by the analysis of the base occurrence in 294 GSS containing 5'-adjacent ingi/RIME sequences. The conserved sequence is present upstream of ingis and RIMEs, suggesting that ingi-encoded enzymatic activities are used for retrotransposition of RIMEs, which are short nonautonomous retroelements. In conclusion, the ingi and RIME retroelements are not randomly distributed in the genome of T. brucei and are preceded by a conserved sequence, which may be the recognition site of the ingi-encoded endonuclease.

  6. Rime and graupel: Description and characterization as revealed by low-temperature scanning electron microscopy

    USGS Publications Warehouse

    Rango, A.; Foster, J.; Josberger, E.G.; Erbe, E.F.; Pooley, C.; Wergin, W.P.

    2003-01-01

    Snow crystals, which form by vapor deposition, occasionally come in contact with supercooled cloud droplets during their formation and descent. When this occurs, the droplets adhere and freeze to the snow crystals in a process known as accretion. During the early stages of accretion, discrete snow crystals exhibiting frozen cloud droplets are referred to as rime. If this process continues, the snow crystal may become completely engulfed in frozen cloud droplets. The resulting particle is known as graupel. Light microscopic investigations have studied rime and graupel for nearly 100 years. However, the limiting resolution and depth of field associated with the light microscope have prevented detailed descriptions of the microscopic cloud droplets and the three-dimensional topography of the rime and graupel particles. This study uses low-temperature scanning electron microscopy to characterize the frozen precipitates that are commonly known as rime and graupel. Rime, consisting of frozen cloud droplets, is observed on all types of snow crystals including needles, columns, plates, and dendrites. The droplets, which vary in size from 10 to 100 μm, frequently accumulate along one face of a single snow crystal, but are found more randomly distributed on aggregations consisting of two or more snow crystals (snowflakes). The early stages of riming are characterized by the presence of frozen cloud droplets that appear as a layer of flattened hemispheres on the surface of the snow crystal. As this process continues, the cloud droplets appear more sinuous and elongate as they contact and freeze to the rimed crystals. The advanced stages of this process result in graupel, a particle 1 to 3 mm across, composed of hundreds of frozen cloud droplets interspersed with considerable air spaces; the original snow crystal is no longer discernible. This study increases our knowledge about the process and characteristics of riming and suggests that the initial appearance of the

  7. Rime and graupel: description and characterization as revealed by low-temperature scanning electron microscopy.

    PubMed

    Rango, Albert; Foster, James; Josberger, Edward G; Erbe, Eric F; Pooley, Christopher; Wergin, William P

    2003-01-01

    Snow crystals, which form by vapor deposition, occasionally come in contact with supercooled cloud droplets during their formation and descent. When this occurs, the droplets adhere and freeze to the snow crystals in a process known as accretion. During the early stages of accretion, discrete snow crystals exhibiting frozen cloud droplets are referred to as rime. If this process continues, the snow crystal may become completely engulfed in frozen cloud droplets. The resulting particle is known as graupel. Light microscopic investigations have studied rime and graupel for nearly 100 years. However, the limiting resolution and depth of field associated with the light microscope have prevented detailed descriptions of the microscopic cloud droplets and the three-dimensional topography of the rime and graupel particles. This study uses low-temperature scanning electron microscopy to characterize the frozen precipitates that are commonly known as rime and graupel. Rime, consisting of frozen cloud droplets, is observed on all types of snow crystals including needles, columns, plates, and dendrites. The droplets, which vary in size from 10 to 100 microm, frequently accumulate along one face of a single snow crystal, but are found more randomly distributed on aggregations consisting of two or more snow crystals (snowflakes). The early stages of riming are characterized by the presence of frozen cloud droplets that appear as a layer of flattened hemispheres on the surface of the snow crystal. As this process continues, the cloud droplets appear more sinuous and elongate as they contact and freeze to the rimed crystals. The advanced stages of this process result in graupel, a particle 1 to 3 mm across, composed of hundreds of frozen cloud droplets interspersed with considerable air spaces; the original snow crystal is no longer discernible. This study increases our knowledge about the process and characteristics of riming and suggests that the initial appearance of the

  8. Phoneme Manipulation Not Onset-Rime Manipulation Ability Is a Unique Predictor of Early Reading

    ERIC Educational Resources Information Center

    Savage, Robert; Carless, Sue

    2005-01-01

    Background: Phonological awareness is known to be an excellent predictor of later reading acquisition. It remains unclear, however, whether phoneme manipulation alone best explains this association or whether an additional direct contribution of onset-rime awareness is predictive. This issue is explored here. Method: A longitudinal study is…

  9. Assessing the potential for passive radio sounding of Europa and Ganymede with RIME and REASON

    NASA Astrophysics Data System (ADS)

    Schroeder, Dustin M.; Romero-Wolf, Andrew; Carrer, Leonardo; Grima, Cyril; Campbell, Bruce A.; Kofman, Wlodek; Bruzzone, Lorenzo; Blankenship, Donald D.

    2016-12-01

    Recent work has raised the potential for Jupiter's decametric radiation to be used as a source for passive radio sounding of its icy moons. Two radar sounding instruments, the Radar for Icy Moon Exploration (RIME) and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) have been selected for ESA and NASA missions to Ganymede and Europa. Here, we revisit the projected performance of the passive sounding concept and assess the potential for its implementation as an additional mode for RIME and REASON. We find that the Signal to Noise Ratio (SNR) of passive sounding can approach or exceed that of active sounding in a noisy sub-Jovian environment, but that active sounding achieves a greater SNR in the presence of quiescent noise and outperforms passive sounding in terms of clutter. We also compare the performance of passive sounding at the 9 MHz HF center frequency of RIME and REASON to other frequencies within the Jovian decametric band. We conclude that the addition of a passive sounding mode on RIME or REASON stands to enhance their science return by enabling sub-Jovian HF sounding in the presence of decametric noise, but that there is not a compelling case for implementation at a different frequency.

  10. Syllable Splitting in Literate and Preliterate Hebrew Speakers: Onsets and Rimes or Bodies and Codas?

    ERIC Educational Resources Information Center

    Share, David L.; Blum, Peri

    2005-01-01

    This study examined consonant-vowel-consonant (CVC) syllable splitting among literate (Grade 2) and preliterate (kindergarten) Hebrew speakers. Consideration of both the architecture of Hebrew orthography and phonology led to the prediction that a body-coda rather than an onset-rime subdivision would predominate. Structured and unstructured tasks…

  11. Sensitivity to Rime Unit Frequency and Children's Early Word-Reading Strategies

    ERIC Educational Resources Information Center

    Coyne, Emily; Farrington-Flint, Lee; Underwood, Jean; Stiller, James

    2012-01-01

    The current work examines children's sensitivity to rime unit spelling-sound correspondences within the context of early word reading as a way of assessing word-specific influences on early word-reading strategies. Sixty 6-7-year-olds participated in an experimental reading task that comprised word items that shared either frequent or infrequent…

  12. Syllable Splitting in Literate and Preliterate Hebrew Speakers: Onsets and Rimes or Bodies and Codas?

    ERIC Educational Resources Information Center

    Share, David L.; Blum, Peri

    2005-01-01

    This study examined consonant-vowel-consonant (CVC) syllable splitting among literate (Grade 2) and preliterate (kindergarten) Hebrew speakers. Consideration of both the architecture of Hebrew orthography and phonology led to the prediction that a body-coda rather than an onset-rime subdivision would predominate. Structured and unstructured tasks…

  13. Rime ice accretion and its effect on airfoil performance. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Bragg, M. B.

    1982-01-01

    A methodology was developed to predict the growth of rime ice, and the resulting aerodynamic penalty on unprotected, subcritical, airfoil surfaces. The system of equations governing the trajectory of a water droplet in the airfoil flowfield is developed and a numerical solution is obtained to predict the mass flux of super cooled water droplets freezing on impact. A rime ice shape is predicted. The effect of time on the ice growth is modeled by a time-stepping procedure where the flowfield and droplet mass flux are updated periodically through the ice accretion process. Two similarity parameters, the trajectory similarity parameter and accumulation parameter, are found to govern the accretion of rime ice. In addition, an analytical solution is presented for Langmuir's classical modified inertia parameter. The aerodynamic evaluation of the effect of the ice accretion on airfoil performance is determined using an existing airfoil analysis code with empirical corrections. The change in maximum lift coefficient is found from an analysis of the new iced airfoil shape. The drag correction needed due to the severe surface roughness is formulated from existing iced airfoil and rough airfoil data. A small scale wind tunnel test was conducted to determine the change in airfoil performance due to a simulated rime ice shape.

  14. Reimagining Coleridge's "Rime of the Ancient Mariner" through Visual and Performing Arts Projects

    ERIC Educational Resources Information Center

    Michaels, Judy Rowe

    2009-01-01

    In this article, the author discusses how students create their arts projects by responding to Samuel Taylor Coleridge's "Rime of the Ancient Mariner." In creating their arts projects, students incorporate film, painting, performance, and other arts in their imaginative and innovative responses to Coleridge's classic work. The author discusses…

  15. Understanding the Role of Riming in Deep Convection Through Variability in Collection Efficiencies and Aerosol Effects

    NASA Astrophysics Data System (ADS)

    Saleeby, S. M.; van den Heever, S. C.; Marinescu, P. J.; Kreidenweis, S. M.; DeMott, P. J.; Tao, W. K.; Matsui, T.; Wu, D.

    2015-12-01

    In many mixed-phase cloud systems, the riming of cloud droplets is a key microphysical process in the growth of precipitation-sized hydrometeors. The relative importance of riming compared to other hydrometeor growth mechanisms depends on the type of cloud system and the mass, size, and number concentration of cloud droplets and ice species. In a perturbed climate state, the nature of deep convection may be altered through changes in the environmental conditions and aerosol concentrations. Such climate-induced variability can modify the dominant microphysical processes that generate precipitation through changes in hydrometeor size spectra. Such changes could either increase or decrease precipitation production and efficiency as well as impact associated morphology of clouds and convection. If the efficiency of the riming process is modified through these climate changes, it can alter the accumulated precipitation, precipitation intensity, spatial and temporal distribution of cloud and ice water, and the radiation budget through the modification of ice spectra and areal coverage of upper-level anvil clouds. The impacts of variability in aerosol concentration and collision efficiencies on the riming process in deep convection is explored through the use of high-resolution cloud resolving model simulations of a squall line that occurred May 20, 2011 over the U.S. central plains during the MC3E field project. Results thus far have demonstrated that changes in the riming rates strongly impact the intensity and partitioning of squall line precipitation between convective and stratiform, the lofting of condensate to upper levels, the vertical distribution of latent heating, and the area and optical thickness of stratiform anvil clouds. Analyses from direct tests of microphysical processes have revealed that a reduction in riming rates leads to less precipitation, greater amounts of lofted cloud water, and greater ice mass in cirrus anvils. Further, an increase in aerosol

  16. Enhancing Physician Assistant Student Clinical Rotation Evaluations With the RIME Scoring Format: A Retrospective 3-Year Analysis.

    PubMed

    Klocko, David J

    2016-11-03

    This article describes a 3-year retrospective analysis of student clinical rotation evaluations using the Reporter-Interpreter-Manager-Educator (RIME) scoring format. The intent of the analysis was to assess scoring trends to determine whether students with high scores on the Physician Assistant National Certifying Exam (PANCE) also achieved high RIME scores on clinical rotations. The top and bottom quartiles of PANCE scores were identified for the University of Texas (UT) Southwestern Medical Center's physician assistant (PA) classes of 2010-2012 (n = 106). RIME scores for the top and bottom quartiles of students (n = 54) also were identified. RIME scores for the same cohort of students were analyzed using the top and bottom quartiles of students' PANCE scores. The Wilcoxon matched-pairs signed rank test revealed that students with top quartile PANCE scores received a higher aggregate RIME score of 557 compared with the lower quartile of PANCE performers' score of 520 (P < .03). Results for RIME scoring trends, PANCE scores, and end-of-rotation examination scores are presented. Students from the UT Southwestern Medical Center's PA classes of 2010-2012 obtained a Manager classification most often (52%), and students with higher PANCE scores also received higher RIME scores on clinical rotations.

  17. Onsets and rimes in a phonologically transparent orthography: differences between good and poor beginning readers of Dutch.

    PubMed

    Geudens, A; Sandra, D

    This study investigates whether beginning readers of Dutch develop onset-rime units when these units are emphasized in their reading method, even when the orthography is transparent at the grapheme-phoneme level. The speed of naming intact pseudowords (wot) was compared with the speed of naming pseudowords with an onset-rime (w ot) or body-coda (wo t) segmentation. Whereas body-coda items consistently slowed down naming for both good and poor readers, the onset-rime effect covaried with reading skill: it changed from inhibitory for good readers to facilitatory for poor readers. Two alternative explanations are proposed.

  18. Wind tunnel investigations on the retention of carboxylic acids during riming

    NASA Astrophysics Data System (ADS)

    Jost, Alexander; Szakáll, Miklós; Diehl, Karoline; Mitra, Subir K.; Borrmann, Stephan

    2015-04-01

    In mid-latitudes, precipitation is mainly initiated via the ice phase in mixed phase clouds. In such clouds the ice particles grow to precipitation sizes at the expense of liquid drops through riming which means that supercooled droplets collide with ice particles and subsequently freeze. Water-soluble trace substances present in the liquid phase might remain only fractionally in the ice phase after freezing. This fractionation is called retention and is an important ratio which quantifies the partitioning of atmospheric trace substances between the phases. Laboratory experiments were carried out at the Mainz vertical wind tunnel to determine the retention of lower mono- and di-carboxylic acids during riming. Due to their low molecular weight and their polarity these acids are water-soluble. In the atmosphere formic acid and acetic acid are the most abundant mono-carboxylic acids in the gas and aqueous phase, thus, they represent the major fraction of carboxylic acids in cloud water. Oxalic and malonic acid are common coatings on aerosol particles because of their relatively low saturation vapor pressure. These di-carboxylic acids might therefore promote the aerosol particles to act as cloud condensation nuclei and additionally contribute to the aqueous phase chemistry in cloud droplets. The conditions during the riming experiments in the wind tunnel were similar to those in atmospheric mixed phase clouds, i.e. temperatures from -18°C to -6 °C, liquid water contents between 0.5 and 1.5 g/m3, and liquid drop radii between 10 and 20 μm. The liquid phase concentrations ranged from 3 to 5 mg/l (4.1 < pH < 4.5). As rime collectors captively floating ice particles and quasi-floating snowflakes with diameters between 0.6 and 1.5 cm were used. The wind speed in the vertical wind tunnel was very close to the terminal velocities of the rime collectors, thus, the ventilation during riming was in the same order of magnitude as under atmospheric riming conditions. After

  19. Water Droplet Impingement on Simulated Glaze, Mixed, and Rime Ice Accretions

    NASA Technical Reports Server (NTRS)

    Papadakis, Michael; Rachman, Arief; Wong, See-Cheuk; Yeong, Hsiung-Wei; Hung, Kuohsing E.; Vu, Giao T.; Bidwell, Colin S.

    2007-01-01

    Water droplet impingement data were obtained at the NASA Glenn Icing Research Tunnel (IRT) for a 36-in. chord NACA 23012 airfoil with and without simulated ice using a dye-tracer method. The simulated ice shapes were defined with the NASA Glenn LEWICE 2.2 ice accretion program and including one rime, four mixed and five glaze ice shapes. The impingement experiments were performed with spray clouds having median volumetric diameters of 20, 52, 111, 154, and 236 micron. Comparisons to the experimental data were generated which showed good agreement for the rime and mixed shapes at lower drop sizes. For larger drops sizes LEWICE 2.2 over predicted the collection efficiencies due to droplet splashing effects which were not modeled in the program. Also for the more complex glaze ice shapes interpolation errors resulted in the over prediction of collection efficiencies in cove or shadow regions of ice shapes.

  20. Syllable splitting in literate and preliterate Hebrew speakers: onsets and rimes or bodies and codas?

    PubMed

    Share, David L; Blum, Peri

    2005-10-01

    This study examined consonant-vowel-consonant (CVC) syllable splitting among literate (Grade 2) and preliterate (kindergarten) Hebrew speakers. Consideration of both the architecture of Hebrew orthography and phonology led to the prediction that a body-coda rather than an onset-rime subdivision would predominate. Structured and unstructured tasks confirmed the claim that there exists a subsyllabic, supraphonemic level of phonological awareness that is more accessible than individual phonemes. However, as predicted, the syllable body rather than the rime was found to be the more accessible biphonemic unit. Moreover, this preference did not appear to be solely the product of orthographic structure; rather it was also inherent in spoken phonology. Access to single phonemes, in contrast, shifted from an early preliteracy advantage for (monophonemic) onsets to a literacy-based preference for codas.

  1. Rime-, mixed- and glaze-ice evaluations of three scaling laws

    NASA Technical Reports Server (NTRS)

    Anderson, David N.

    1994-01-01

    This report presents the results of tests at NASA Lewis to evaluate three icing scaling relationships or 'laws' for an unheated model. The laws were LWC x time = constant, one proposed by a Swedish-Russian group and one used at ONERA in France. Icing tests were performed in the NASA Lewis Icing Research Tunnel (IRT) with cylinders ranging from 2.5- to 15.2-cm diameter. Reference conditions were chosen to provide rime, mixed and glaze ice. Scaled conditions were tested for several scenarios of size and velocity scaling, and the resulting ice shapes compared. For rime-ice conditions, all three of the scaling laws provided scaled ice shapes which closely matched reference ice shapes. For mixed ice and for glaze ice none of the scaling laws produced consistently good simulation of the reference ice shapes. Explanations for the observed results are proposed, and scaling issues requiring further study are identified.

  2. Using Field and Satellite Measurements to Improve Snow and Riming Processes in Cloud Resolving Models

    NASA Technical Reports Server (NTRS)

    Colle, Brian A.; Molthan, Andrew L.

    2013-01-01

    The representation of clouds in climate and weather models is a driver in forecast uncertainty. Cloud microphysics parameterizations are challenged by having to represent a diverse range of ice species. Key characteristics of predicted ice species include habit and fall speed, and complex interactions that result from mixed-phased processes like riming. Our proposed activity leverages Global Precipitation Measurement (GPM) Mission ground validation studies to improve parameterizations

  3. Pilot study of a 'RIME'-based tool for giving feedback in a multi-specialty longitudinal clerkship.

    PubMed

    DeWitt, Dawn; Carline, Jan; Paauw, Douglas; Pangaro, Louis

    2008-12-01

    The Reporter-Interpreter-Manager-Educator (RIME) evaluation framework is intuitive and reliable. Our preceptors' frustration with using summative tools for formative feedback and the hypothesis that the RIME vocabulary might improve students' and preceptors' experiences with feedback prompted us to develop and pilot a RIME-based feedback tool. The tool was based on the RIME vocabulary, which has previously been used for evaluation. As interpersonal skills and professionalism are difficult areas in which to give feedback, we added these as explicit categories. We piloted the tool in a longitudinal, 5-month, multi-specialty clerkship. Preceptors completed pre- and post-introductory workshop surveys. Students completed post-workshop and post-clerkship surveys. Preceptors (n = 14) and students (n = 8) preferred RIME-based feedback to 'usual feedback' (previously given using end-of-clerkship evaluation forms). After the initial workshop, preceptors expected that giving feedback, including critical feedback, would be easier. After the 5-month clerkship, students reported receiving more feedback than in previous clerkships and rated feedback given using this tool more highly (P = 0.002; effect size 1.2). Students also felt it helped them understand specifically how to improve their performance (P = 0.003; effect size 1.2). In this pilot study, preceptors and students preferred feedback with a specific RIME-based tool. Students felt such feedback was more useful and helped them identify specifically how to improve. Whether this method can improve student performance through improved feedback remains an area for further research.

  4. Remote sensing of ice density and riming processes with Doppler radar

    NASA Astrophysics Data System (ADS)

    Mason, Shannon; Chiu, Christine; Hogan, Robin; Kneifel, Stefan; Moisseev, Dmitri

    2017-04-01

    Satellite radar-lidar measurements have facilitated advances in global estimates of ice cloud and precipitation, especially in remote maritime and polar environments. A major uncertainty is the composition and density of ice particles, which depend on ice growth processes such as aggregation, and riming in the presence of supercooled liquid droplets. The upcoming EarthCARE satellite, the first Doppler radar in space, will be capable of retrieving ice density by using Doppler velocity measurements to distinguish fast-falling rimed particles from lighter, slower aggregates. In this study we use vertically-pointing Doppler radar measurements from the ARM mobile facility at Hyytiälä, Finland to retrieve the fractional volume of rimed ice and aggregate snow. The retrievals are made using CAPTIVATE, the novel variational retrieval scheme developed for EarthCARE, and are compared against in situ measurements at the surface. These results will provide insights into ice growth processes, and will inform to what extent the new spaceborne Doppler radar capability stands to reduce uncertainties in retrievals of ice water content and the detection of mixed-phase cloud in polar regions.

  5. Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

    NASA Astrophysics Data System (ADS)

    Kalesse, H.; Szyrmer, W.; Kneifel, S.; Kollias, P.; Luke, E.

    2015-10-01

    Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediments through a supercooled liquid water (SLW) layer. The observations were collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland during the BAECC (Biogenic Aerosols - Effects on Clouds and Climate Snowfall Experiment) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are taken into account by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in-situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.

  6. Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

    DOE PAGES

    Kalesse, Heike; Szyrmer, Wanda; Kneifel, Stefan; ...

    2016-03-09

    In this paper, Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediment through a supercooled liquid water (SLW) layer. The focus is on the "golden sample" case study for this type of analysis based on observations collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland, during the Biogenic Aerosols – Effects on Clouds and Climate (BAECC) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyondmore » the traditional use of spectral moments. Dynamical effects are considered by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. In conclusion, this suggests that in situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.« less

  7. Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

    SciTech Connect

    Kalesse, Heike; Szyrmer, Wanda; Kneifel, Stefan; Kollias, Pavlos; Luke, Edward

    2016-03-09

    In this paper, Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediment through a supercooled liquid water (SLW) layer. The focus is on the "golden sample" case study for this type of analysis based on observations collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland, during the Biogenic Aerosols – Effects on Clouds and Climate (BAECC) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are considered by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. In conclusion, this suggests that in situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.

  8. Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

    NASA Astrophysics Data System (ADS)

    Kalesse, Heike; Szyrmer, Wanda; Kneifel, Stefan; Kollias, Pavlos; Luke, Edward

    2016-03-01

    Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediment through a supercooled liquid water (SLW) layer. The focus is on the "golden sample" case study for this type of analysis based on observations collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland, during the Biogenic Aerosols - Effects on Clouds and Climate (BAECC) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are considered by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.

  9. Combining dual-polarization radar and ground-based observations to study the effect of riming on ice particles

    NASA Astrophysics Data System (ADS)

    Moisseev, Dmitri; von Lerber, Annakaisa; Tiira, Jussi

    2017-04-01

    Recently a new microphysical scheme based on a single ice-phase category was proposed for the use in numerical weather prediction models. In the proposed scheme, ice particle properties are predicted and vary in time and space. One of the attributes of the proposed scheme is that the prefactor of a power-law relation that links mass and size of ice particles is determined by the rime mass fraction, while the exponent is kept constant. According to this the maximum dimensions of ice particles do not change during riming until graupel growth phase is reached. The dual-polarization radar observations given an additional insight on what are the physical properties of ice particles. Often, it is assumed that differential reflectivity should decrease because of riming. The motivation for this is that heavy riming would transform an ice particle to graupel. A graupel particle typically would have an almost spherical shape and therefore the differential reflectivity will become smaller. On the other hand, at the earlier stages ice particle shape may not change much, while its mass and therefore the density increases. This would lead to the increase of the differential reflectivity, for example. By combining ground-based observations, which allow to quantify the effect of riming on snowfall, and dual-polarization radar observations we investigate the impact of riming on ice particle properties, i.e. mass, density and shape. Furthermore, a connection between, bulk properties of ice particles, liquid water path, radar equivalent reflectivity factor and precipitation rate observations is established. The study is based on data collected during US DOE Biogenic Aerosols - Effects on Clouds and Climate (BAECC) field campaign that took place in Hyytiala, Finland. A detailed analysis of two events is presented to illustrate the method.

  10. Assessing the Effectiveness of Two Theoretically Motivated Computer-Assisted Reading Interventions in the United Kingdom: GG Rime and GG Phoneme

    ERIC Educational Resources Information Center

    Kyle, Fiona; Kujala, Janne; Richardson, Ulla; Lyytinen, Heikki; Goswami, Usha

    2013-01-01

    We report an empirical comparison of the effectiveness of two theoretically motivated computer-assisted reading interventions (CARI) based on the Finnish GraphoGame CARI: English GraphoGame Rime (GG Rime) and English GraphoGame Phoneme (GG Phoneme). Participants were 6-7-year-old students who had been identified by their teachers as being…

  11. Solid hydrometeor classification and riming degree estimation from pictures collected with a Multi-Angle Snowflake Camera

    NASA Astrophysics Data System (ADS)

    Praz, Christophe; Roulet, Yves-Alain; Berne, Alexis

    2017-04-01

    A new method to automatically classify solid hydrometeors based on Multi-Angle Snowflake Camera (MASC) images is presented. For each individual image, the method relies on the calculation of a set of geometric and texture-based descriptors to simultaneously identify the hydrometeor type (among six predefined classes), estimate the degree of riming and detect melting snow. The classification tasks are achieved by means of a regularized multinomial logistic regression (MLR) model trained over more than 3000 MASC images manually labeled by visual inspection. In a second step, the probabilistic information provided by the MLR is weighed on the three stereoscopic views of the MASC in order to assign a unique label to each hydrometeor. The accuracy and robustness of the proposed algorithm is evaluated on data collected in the Swiss Alps and in Antarctica. The algorithm achieves high performance, with a hydrometeor-type classification accuracy and Heidke skill score of 95 % and 0.93, respectively. The degree of riming is evaluated by introducing a riming index ranging between zero (no riming) and one (graupel) and characterized by a probable error of 5.5 %. A validation study is conducted through a comparison with an existing classification method based on two-dimensional video disdrometer (2DVD) data and shows that the two methods are consistent.

  12. Rhyming Words and Onset-Rime Constituents: An Inquiry into Structural Breaking Points and Emergent Boundaries in the Syllable

    ERIC Educational Resources Information Center

    Geudens, Astrid; Sandra, Dominiek; Martensen, Heike

    2005-01-01

    Geudens and Sandra, in their 2003 study, investigated the special role of onsets and rimes in Dutch-speaking children's explicit phonological awareness. In the current study, we tapped implicit phonological knowledge using forced-choice similarity judgment (Experiment 1) and recall of syllable lists (Experiment 2). In Experiment 1, Dutch-speaking…

  13. Rhyming Words and Onset-Rime Constituents: An Inquiry into Structural Breaking Points and Emergent Boundaries in the Syllable

    ERIC Educational Resources Information Center

    Geudens, Astrid; Sandra, Dominiek; Martensen, Heike

    2005-01-01

    Geudens and Sandra, in their 2003 study, investigated the special role of onsets and rimes in Dutch-speaking children's explicit phonological awareness. In the current study, we tapped implicit phonological knowledge using forced-choice similarity judgment (Experiment 1) and recall of syllable lists (Experiment 2). In Experiment 1, Dutch-speaking…

  14. Environmental Role of Rime Chemistry at Selected Mountain Sites in Poland

    NASA Astrophysics Data System (ADS)

    Godek, Michał; Błaś, Marek; Sobik, Mieczysław; Polkowska, Żaneta; Cichała-Kamrowska, Katarzyna; Namieśnik, Jacek

    2012-05-01

    The results of field experiments on fog pollutant deposition enhanced by local mountain climate, completed by the dendrochronological analysis of the forest response, are presented in this paper. In spite of their low absolute altitude (1,000-1,600 m a.s.l), the Sudetes and the Silesian Beskid form a noticeable orographic barrier for the airflow of the humid Atlantic air masses. This results in the increase of cloudiness and fog frequency as well as both atmospheric precipitation and horizontal precipitation volume. Between January and December 2009 the daily samples of atmospheric precipitation and rime were collected on three selected mountain tops of similar height. The selected measurement sites were situated along a 300 km WNW-ESE profile parallel to the direction of the prevailing atmospheric circulation. High day-to-day variability of rime water volume, the total ionic content and chemical composition of the individual samples were typical of each measurement site and depended on the emission patterns, synoptic situation and the local climatic conditions influenced chiefly by terrain relief. Significantly larger rime efficiency and pollution deposition via fog were observed at the westernmost Szrenica Mt site rather than more to the southeast at Śnieżnik Mt and Skrzyczne Mt. This difference should be explained by more intense orographic deformation of predominant airflow from the western sector as well as the higher liquid water content of fog in the vicinity of Szrenica. Both temporal and spatial variability of fog deposition correlates closely with the health status of the drilled trees of Norway Spruce ( Picea Abies) in the Śnieżnik Massif. The averaged annual tree rings width near the local tree line (1,350 m a.s.l.) on the summit dome of Śnieżnik decreased by 71% between 1950 and the early 1980s. This is also the area of the highest rate of atmospheric pollutant deposition due to particularly important role of fog. At an altitude of 1,200 m a

  15. Orthographic Consistency and Word-Frequency Effects in Auditory Word Recognition: New Evidence from Lexical Decision and Rime Detection

    PubMed Central

    Petrova, Ana; Gaskell, M. Gareth; Ferrand, Ludovic

    2011-01-01

    Many studies have repeatedly shown an orthographic consistency effect in the auditory lexical decision task. Words with phonological rimes that could be spelled in multiple ways (i.e., inconsistent words) typically produce longer auditory lexical decision latencies and more errors than do words with rimes that could be spelled in only one way (i.e., consistent words). These results have been extended to different languages and tasks, suggesting that the effect is quite general and robust. Despite this growing body of evidence, some psycholinguists believe that orthographic effects on spoken language are exclusively strategic, post-lexical, or restricted to peculiar (low-frequency) words. In the present study, we manipulated consistency and word-frequency orthogonally in order to explore whether the orthographic consistency effect extends to high-frequency words. Two different tasks were used: lexical decision and rime detection. Both tasks produced reliable consistency effects for both low- and high-frequency words. Furthermore, in Experiment 1 (lexical decision), an interaction revealed a stronger consistency effect for low-frequency words than for high-frequency words, as initially predicted by Ziegler and Ferrand (1998), whereas no interaction was found in Experiment 2 (rime detection). Our results extend previous findings by showing that the orthographic consistency effect is obtained not only for low-frequency words but also for high-frequency words. Furthermore, these effects were also obtained in a rime detection task, which does not require the explicit processing of orthographic structure. Globally, our results suggest that literacy changes the way people process spoken words, even for frequent words. PMID:22025916

  16. Rapid immunoprecipitation mass spectrometry of endogenous proteins (RIME) for analysis of chromatin complexes.

    PubMed

    Mohammed, Hisham; Taylor, Christopher; Brown, Gordon D; Papachristou, Evaggelia K; Carroll, Jason S; D'Santos, Clive S

    2016-02-01

    Rapid immunoprecipitation mass spectrometry of endogenous protein (RIME) is a method that allows the study of protein complexes, in particular chromatin and transcription factor complexes, in a rapid and robust manner by mass spectrometry (MS). The method can be used in parallel with chromatin immunoprecipitation-sequencing (ChIP-seq) experiments to provide information on both the cistrome and interactome for a given protein. The method uses formaldehyde fixation to stabilize protein complexes. By using antibodies against the endogenous target, the cross-linked complex is immunoprecipitated, rigorously washed, and then digested into peptides while avoiding antibody contamination (on-bead digestion). By using this method, MS identification of the target protein and several dozen interacting proteins is possible using a 100-min LC-MS/MS run. The protocol does not require substantial proteomics expertise, and it typically takes 2-3 d from the collection of material to results.

  17. Chemistry of riming: the retention of organic and inorganic atmospheric trace constituents

    NASA Astrophysics Data System (ADS)

    Jost, Alexander; Szakáll, Miklós; Diehl, Karoline; Mitra, Subir K.; Borrmann, Stephan

    2017-08-01

    During free fall in clouds, ice hydrometeors such as snowflakes and ice particles grow effectively by riming, i.e., the accretion of supercooled droplets. Volatile atmospheric trace constituents dissolved in the supercooled droplets may remain in ice during freezing or may be released back to the gas phase. This process is quantified by retention coefficients. Once in the ice phase the trace constituents may be vertically redistributed by scavenging and subsequent precipitation or by evaporation of these ice hydrometeors at high altitudes. Retention coefficients of the most dominant carboxylic acids and aldehydes found in cloud water were investigated in the Mainz vertical wind tunnel under dry-growth (surface temperature less than 0 °C) riming conditions which are typically prevailing in the mixed-phase zone of convective clouds (i.e., temperatures from -16 to -7 °C and a liquid water content (LWC) of 0. 9 ± 0. 2 g m-3). The mean retention coefficients of formic and acetic acids are found to be 0. 68 ± 0. 09 and 0. 63 ± 0. 19. Oxalic and malonic acids as well as formaldehyde show mean retention coefficients of 0. 97 ± 0. 06, 0. 98 ± 0. 08, and 0. 97 ± 0. 11, respectively. Application of a semi-empirical model on the present and earlier wind tunnel measurements reveals that retention coefficients can be well interpreted by the effective Henry's law constant accounting for solubility and dissociation. A parameterization for the retention coefficients has been derived for substances whose aqueous-phase kinetics are fast compared to mass transport timescales. For other cases, the semi-empirical model in combination with a kinetic approach is suited to determine the retention coefficients. These may be implemented in high-resolution cloud models.

  18. ETUDE - European Trade Union Distance Education.

    ERIC Educational Resources Information Center

    Creanor, Linda; Walker, Steve

    2000-01-01

    Describes transnational distance learning activities among European trade union educators carried out as part of the European Trade Union Distance Education (ETUDE) project, supported by the European Commission. Highlights include the context of international trade union distance education; tutor training course; tutors' experiences; and…

  19. Centre National d'Etudes Spatiales

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The Centre National d'Etudes Spatiales (CNES) draws up, proposes and conducts France's space policy. Its role is to develop the uses of space, to meet the civilian and military needs of public bodies and of the scientific community, and to foster the development and dissemination of new applications, designed to create wealth and jobs....

  20. Apport du rayonnement synchrotron à l'étude de cheveux archéologiques

    NASA Astrophysics Data System (ADS)

    Bertrand, L.; Chevallier, P.; Doucet, J.; Simionovici, A.; Tsoucaris, G.; Walter, P.

    2002-07-01

    La préservation dans certains contextes archéologiques des cheveux humains et des fibres animales est favorisée par leur transformation chimique au contact d'objets métalliques. Afin de mieux comprendre les phénomènes complexes mis en jeu, nous avons étudié expérimentalement la fixation de cations métalliques (Cu et Pb) dans des cheveux modèles à partir de différentes méthodes de caractérisation utilisant le rayonnement X synchrotron. Nous avons ainsi pu mettre en évidence la fixation spécifique d'une partie de ces cations au sein des lipides structurés du cheveu. La comparaison entre échantillons modèles et archéologiques apporte de nouvelles données concernant les premières étapes d'altération des cheveux archéologiques.

  1. Simulations of Severe Tropical Cyclone Nargis over the Bay of Bengal Using RIMES Operational System

    NASA Astrophysics Data System (ADS)

    Raju, P. V. S.; Potty, Jayaraman; Mohanty, U. C.

    2012-10-01

    The Regional Integrated Multi-Hazard Early Warning System (RIMES), an international, intergovernmental organization based in Thailand is engaged in disaster risk reduction over the Asia-Pacific region through early warning information. In this paper, RIMES' customized Weather Research Forecast (WRF) model has been used to evaluate the simulations of cyclone Nargis which hit Myanmar on 2 May 2008, the most deadly severe weather event in the history of Myanmar. The model covers a domain of 35ºE to 145ºE in the east—west direction and 12ºS to 40ºN in the north—south direction in order to cover Asia and east Africa with a resolution of 9 km in the horizontal and 28 vertical levels. The initial and boundary conditions for the simulations were provided by the National Center for Environmental Prediction-Global Forecast System (NCEP-GFS) available at 1º lon/lat resolution. An attempt is being made to critically evaluate the simulation of cyclone Nargis by seven set of simulations in terms of track, intensity and landfall time of the cyclone. The seven sets of model simulations were initialized every 12 h starting from 0000 UTC 28 April to 01 May 2008. Tropical Rainfall Measurement Mission (TRMM) precipitation (mm) is used to evaluate the performance of the simulations of heavy rainfall associated with the tropical cyclone. The track and intensity of the simulated cyclone are compared by making use of Joint Typhoon Warning Center (JTWC) data sets. The results indicate that the landfall time, the distribution and intensity of the rainfall, pressure and wind field are well simulated as compared with the JTWC estimates. The average landfall track error for all seven simulations was 64 km with an average time error of about 5 h. The average intensity error of central pressure in all the simulations were found out to be approximately 6 hPa more than the JTWC estimates and in the case of wind, the simulations under predicted it by an average of 12 m s-1.

  2. Super flame-retardant lightweight rime-like carbon-phenolic nanofoam

    PubMed Central

    Cheng, Haiming; Hong, Changqing; Zhang, Xinghong; Xue, Huafei; Meng, Songhe; Han, Jiecai

    2016-01-01

    The desire for lightweight nanoporous materials with high-performance thermal insulation and efficient anti-ablation resistance for energy conservation and thermal protection/insulation has greatly motivated research and development recently. The main challenge to synthesize such lightweight materials is how to balance the relationship of low thermal conductivity and flame retardancy. Herein, we propose a new concept of lightweight “rime-like” structured carbon-phenolic nanocomposites to solve this problem, where the 3D chopped network-structured carbon fiber (NCF) monoliths are incorporated with nanoporous phenolic aerogel to retain structural and functional integrity. The nanometer-scaled porous phenolic (NP) was synthesized through polymerization-induced phase separation and ambient pressure drying using phenolic resin (PR) solution as reaction source, ethylene glycol (EG) as solvent and hexamethylenetetramine (HMTA) as catalyst. We demonstrate that the as-prepared NCF-NP nanocomposite exhibits with a low density of 0.25–0.35 g/cm3, low thermal conductivity of 0.125 Wm−1K−1 and outstanding flame retardancy exceeding 2000 °C under arc-jet wind tunnel simulation environment. Our results show that the synthesis strategy is a promising approach for producing nanocomposites with excellent high-temperature heat blocking property. PMID:27629114

  3. Super flame-retardant lightweight rime-like carbon-phenolic nanofoam

    NASA Astrophysics Data System (ADS)

    Cheng, Haiming; Hong, Changqing; Zhang, Xinghong; Xue, Huafei; Meng, Songhe; Han, Jiecai

    2016-09-01

    The desire for lightweight nanoporous materials with high-performance thermal insulation and efficient anti-ablation resistance for energy conservation and thermal protection/insulation has greatly motivated research and development recently. The main challenge to synthesize such lightweight materials is how to balance the relationship of low thermal conductivity and flame retardancy. Herein, we propose a new concept of lightweight “rime-like” structured carbon-phenolic nanocomposites to solve this problem, where the 3D chopped network-structured carbon fiber (NCF) monoliths are incorporated with nanoporous phenolic aerogel to retain structural and functional integrity. The nanometer-scaled porous phenolic (NP) was synthesized through polymerization-induced phase separation and ambient pressure drying using phenolic resin (PR) solution as reaction source, ethylene glycol (EG) as solvent and hexamethylenetetramine (HMTA) as catalyst. We demonstrate that the as-prepared NCF-NP nanocomposite exhibits with a low density of 0.25-0.35 g/cm3, low thermal conductivity of 0.125 Wm-1K-1 and outstanding flame retardancy exceeding 2000 °C under arc-jet wind tunnel simulation environment. Our results show that the synthesis strategy is a promising approach for producing nanocomposites with excellent high-temperature heat blocking property.

  4. Super flame-retardant lightweight rime-like carbon-phenolic nanofoam.

    PubMed

    Cheng, Haiming; Hong, Changqing; Zhang, Xinghong; Xue, Huafei; Meng, Songhe; Han, Jiecai

    2016-09-15

    The desire for lightweight nanoporous materials with high-performance thermal insulation and efficient anti-ablation resistance for energy conservation and thermal protection/insulation has greatly motivated research and development recently. The main challenge to synthesize such lightweight materials is how to balance the relationship of low thermal conductivity and flame retardancy. Herein, we propose a new concept of lightweight "rime-like" structured carbon-phenolic nanocomposites to solve this problem, where the 3D chopped network-structured carbon fiber (NCF) monoliths are incorporated with nanoporous phenolic aerogel to retain structural and functional integrity. The nanometer-scaled porous phenolic (NP) was synthesized through polymerization-induced phase separation and ambient pressure drying using phenolic resin (PR) solution as reaction source, ethylene glycol (EG) as solvent and hexamethylenetetramine (HMTA) as catalyst. We demonstrate that the as-prepared NCF-NP nanocomposite exhibits with a low density of 0.25-0.35 g/cm(3), low thermal conductivity of 0.125 Wm(-1)K(-1) and outstanding flame retardancy exceeding 2000 °C under arc-jet wind tunnel simulation environment. Our results show that the synthesis strategy is a promising approach for producing nanocomposites with excellent high-temperature heat blocking property.

  5. Application des codes de Monte Carlo à la radiothérapie par rayonnement à faible TEL

    NASA Astrophysics Data System (ADS)

    Marcié, S.

    1998-04-01

    In radiation therapy, there is low LET rays: photons of 60Co, photons and electrons to 4 at 25 MV created in a linac, photons 137Cs, of 192Ir and of 125I. To know the most exactly possible the dose to the tissu by this rays, software and measurements are used. With the development of the power and the capacity of computers, the application of Monte Carlo codes expand to the radiation therapy which have permitted to better determine effects of rays and spectra, to explicit parameters used in dosimetric calculation, to verify algorithms , to study measuremtents systems and phantoms, to calculate the dose in inaccessible points and to consider the utilization of new radionuclides. En Radiothérapie, il existe une variété, de rayonnements ? faible TLE : photons du cobalt 60, photons et ,électron de 4 à? 25 MV générés dans des accélérateurs linéaires, photons du césium 137, de l'iridium 192 et de l'iode 125. Pour connatre le plus exactement possible la dose délivrée aux tissus par ces rayonnements, des logiciels sont utilisés ainsi que des instruments de mesures. Avec le développement de la puissance et de la capacité, des calculateurs, l'application des codes de Monte Carlo s'est ,étendue ? la Radiothérapie ce qui a permis de mieux cerner les effets des rayonnements, déterminer les spectres, préciser les valeurs des paramètres utilisés dans les calculs dosimétriques, vérifier les algorithmes, ,étudier les systèmes de mesures et les fantomes utilisés, calculer la dose en des points inaccessibles ?à la mesure et envisager l'utilisation de nouveaux radio,éléments.

  6. CAPELLA : une source de rayonnement extrême UV à 13.5 nm par décharge capillaire

    NASA Astrophysics Data System (ADS)

    Sarroukh, O.; Robert, E.; Gonthiez, T.; Thomann, A. L.; Viladrosa, R.; Fleurier, C.; Pouvesle, J. M.; Cachoncinlle, C.

    2003-06-01

    Au GREMI, nous étudions le fonctionnement d'une lampe de rayonnement Extrême Ultraviolet (EUV) émettant à 13.5nm: CAPELLA. Cette lampe consiste en une décharge capillaire dans un flux de xénon continu à basse pression. L'utilisation de Xénon à basse pression dans cette décharge permet la production de photons de faible longueur d'onde dans l'EUV. Dans cet article, nous présentons l'étude et la caractérisation de cette lampe ainsi que ses principales performances, en particulier les résultats des analyses des débris émis par la lampe pendant quelques millions de tirs.

  7. Action Research of a Color-Coded, Onset-Rime Decoding Intervention: Examining the Effects with First Grade Students Identified as at Risk

    ERIC Educational Resources Information Center

    Wall, Candace A.; Rafferty, Lisa A.; Camizzi, Mariya A.; Max, Caroline A.; Van Blargan, David M.

    2016-01-01

    Many students who struggle to obtain the alphabetic principle are at risk for being identified as having a reading disability and would benefit from additional explicit phonics instruction as a remedial measure. In this action research case study, the research team conducted two experiments to investigate the effects of a color-coded, onset-rime,…

  8. Text Comprehension in Chinese Children: Relative Contribution of Verbal Working Memory, Pseudoword Reading, Rapid Automated Naming, and Onset-Rime Phonological Segmentation

    ERIC Educational Resources Information Center

    Leong, Che Kan; Tse, Shek Kam; Loh, Ka Yee; Hau, Kit Tai

    2008-01-01

    The present study examined the role of verbal working memory (memory span, tongue twister), 2-character Chinese pseudoword reading, rapid automatized naming (letters, numbers), and phonological segmentation (deletion of rimes and onsets) in inferential text comprehension in Chinese in 518 Chinese children in Hong Kong in Grades 3 to 5. It was…

  9. Action Research of a Color-Coded, Onset-Rime Decoding Intervention: Examining the Effects with First Grade Students Identified as at Risk

    ERIC Educational Resources Information Center

    Wall, Candace A.; Rafferty, Lisa A.; Camizzi, Mariya A.; Max, Caroline A.; Van Blargan, David M.

    2016-01-01

    Many students who struggle to obtain the alphabetic principle are at risk for being identified as having a reading disability and would benefit from additional explicit phonics instruction as a remedial measure. In this action research case study, the research team conducted two experiments to investigate the effects of a color-coded, onset-rime,…

  10. Text Comprehension in Chinese Children: Relative Contribution of Verbal Working Memory, Pseudoword Reading, Rapid Automated Naming, and Onset-Rime Phonological Segmentation

    ERIC Educational Resources Information Center

    Leong, Che Kan; Tse, Shek Kam; Loh, Ka Yee; Hau, Kit Tai

    2008-01-01

    The present study examined the role of verbal working memory (memory span, tongue twister), 2-character Chinese pseudoword reading, rapid automatized naming (letters, numbers), and phonological segmentation (deletion of rimes and onsets) in inferential text comprehension in Chinese in 518 Chinese children in Hong Kong in Grades 3 to 5. It was…

  11. Lead fluxes and 206Pb/207Pb isotope ratios in rime and snow collected at remote mountain-top locations (Czech Republic, Central Europe): Patterns and sources

    NASA Astrophysics Data System (ADS)

    Cimova, Nikoleta; Novak, Martin; Chrastny, Vladislav; Curik, Jan; Veselovsky, Frantisek; Blaha, Vladimir; Prechova, Eva; Pasava, Jan; Houskova, Marie; Bohdalkova, Leona; Stepanova, Marketa; Mikova, Jitka; Krachler, Michael; Komarek, Arnost

    2016-10-01

    During three winter seasons (2009-2011), Pb concentrations were measured in precipitation at 10 high-elevation sites in the Czech Republic, close to the borders with Austria, Germany, Poland, and Slovakia. Soluble and insoluble Pb forms were quantified in snow (vertical deposition), and rime (horizontal deposition). The objective was to compare Pb input fluxes into ecosystems via vertical and horizontal deposition, and to identify the residual Pb pollution sources in an era of rapidly decreasing industrial pollution. Lead soluble in diluted HNO3 made up 96% of total Pb deposition, with the remaining 4% Pb bound mainly in silicates. Three times higher concentrations of soluble Pb in rime than in snow, and 2.5 times higher concentrations of insoluble Pb in rime than in snow were associated with slightly different Pb isotope ratios. On average, the 206Pb/207Pb ratios in rime were higher than those in snow. Higher mean 206Pb/207Pb ratios of insoluble Pb (1.175) than in soluble Pb (1.165) may indicate an increasing role of geogenic Pb in recent atmospheric deposition. A distinct reversal to more radiogenic 206Pb/207Pb ratios in snow and rime in 2010, compared to literature data from rain-fed Sphagnum peatlands (1800-2000 A.D.), documented a recent decrease in anthropogenic Pb in the atmosphere of Central Europe. Since the early 1980s, Pb concentrations in snow decreased 18 times in the rural south of the Czech Republic, but only twice in the industrial north of the Czech Republic. Isotope signatures indicated that Pb in today's atmospheric deposition is mainly derived from Mesozoic ores mined/processed in Poland and coal combustion in the Czech Republic and Poland.

  12. Numerical Analysis Using WRF-SBM for the Cloud Microphysical Structures in the C3VP Field Campaign: Impacts of Supercooled Droplets and Resultant Riming on Snow Microphysics

    NASA Technical Reports Server (NTRS)

    Iguchi, Takamichi; Matsui, Toshihisa; Shi, Jainn J.; Tao, Wei-Kuo; Khain, Alexander P.; Hao, Arthur; Cifelli, Robert; Heymsfield, Andrew; Tokay, Ali

    2012-01-01

    Two distinct snowfall events are observed over the region near the Great Lakes during 19-23 January 2007 under the intensive measurement campaign of the Canadian CloudSat/CALIPSO validation project (C3VP). These events are numerically investigated using the Weather Research and Forecasting model coupled with a spectral bin microphysics (WRF-SBM) scheme that allows a smooth calculation of riming process by predicting the rimed mass fraction on snow aggregates. The fundamental structures of the observed two snowfall systems are distinctly characterized by a localized intense lake-effect snowstorm in one case and a widely distributed moderate snowfall by the synoptic-scale system in another case. Furthermore, the observed microphysical structures are distinguished by differences in bulk density of solid-phase particles, which are probably linked to the presence or absence of supercooled droplets. The WRF-SBM coupled with Goddard Satellite Data Simulator Unit (G-SDSU) has successfully simulated these distinctive structures in the three-dimensional weather prediction run with a horizontal resolution of 1 km. In particular, riming on snow aggregates by supercooled droplets is considered to be of importance in reproducing the specialized microphysical structures in the case studies. Additional sensitivity tests for the lake-effect snowstorm case are conducted utilizing different planetary boundary layer (PBL) models or the same SBM but without the riming process. The PBL process has a large impact on determining the cloud microphysical structure of the lake-effect snowstorm as well as the surface precipitation pattern, whereas the riming process has little influence on the surface precipitation because of the small height of the system.

  13. Diffusion des rayonnements X et visibles ; microscopie en champ proche : utilisation comparée pour la caractérisation des surfaces

    NASA Astrophysics Data System (ADS)

    Tollens, E.; Menecier, S.; Haidar, Y.; Zerrouki, C.; Chassevent, M.; de Fornel, F.; Bonnet, J. J.

    2004-11-01

    Trois méthodes ont été utilisées pour caractériser la rugosité de quelques échantillons. Deux de ces méthodes sont basées sur la mesure du rayonnement diffusé (visible et X). La troisième utilise la microscopie en champ proche (MCP). Dans un premier temps, une comparaison des deux premières techniques a été menée en utilisant une même théorie vectorielle de la diffusion. Bien adaptée au domaine du visible, cette théorie peut aussi être utilisée dans le cas du rayonnement X. Les densités spectrales de puissance (dsp) de la rugosité, déterminées expérimentalement pour deux échantillons d'Alacrite XSH (alliage quaternaire à base de cobalt utilisé en métrologie des masses), montrent des allures identiques dans le cas du visible et du rayonnement X à des incidences très rasantes. Dans un deuxième temps, la hauteur quadratique moyenne δ , caractéristique de la rugosité de ces deux échantillons, a été déterminée de façon "directe" par microscopie en champ proche, et à partir des dsp pour les deux autres techniques. La restriction à une bande commune des fréquences spatiales accessibles à ces techniques, conduit à des valeurs de δ comparables aux incertitudes près. Une validation des mesures X ainsi faite, un accent est mis sur leur apport complémentaire par rapport au visible.

  14. Atmospheric deposition of beryllium in Central Europe: comparison of soluble and insoluble fractions in rime and snow across a pollution gradient.

    PubMed

    Bohdalkova, Leona; Novak, Martin; Voldrichova, Petra; Prechova, Eva; Veselovsky, Frantisek; Erbanova, Lucie; Krachler, Michael; Komarek, Arnost; Mikova, Jitka

    2012-11-15

    Little is known about atmospheric input of beryllium (Be) into ecosystems, despite its highly toxic behavior. For three consecutive winters (2009-2011), we measured Be concentrations in horizontal deposition (rime) and vertical deposition (snow) at 10 remote mountain-top locations in the Czech Republic, Central Europe. Beryllium was determined both in filtered waters, and in HF digests of insoluble particles. Across the sites, soluble Be concentrations in rime were 7 times higher, compared to snow (6.1 vs. 0.9ng·L(-1)). Rime scavenged the pollution-rich lower segments of clouds. The lowest Be concentrations were detected in the soluble fraction of snow. Across the sites, 34% of total Be deposition occurred in the form of soluble (bioavailable) Be, the rest were insoluble particles. Beryllium fluxes decreased in the order: vertical dry deposition insoluble>vertical dry deposition soluble>horizontal deposition soluble>vertical wet deposition insoluble>vertical wet deposition soluble>horizontal deposition insoluble. The average contributions of these Be forms to total deposition were 56, 21, 8, 7, 5 and 3%, respectively. Sites in the northeast were more Be-polluted than the rest of the country with sources of pollution in industrial Silesia. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Scavenging of atmospheric constituents in mixed phase clouds at the high-alpine site jungfraujoch—part II. Influence of riming on the scavenging of particulate and gaseous chemical species

    NASA Astrophysics Data System (ADS)

    Poulida, O.; Schwikowski, M.; Baltensperger, U.; Staehelin, J.; Gaeggeler, H. W.

    The importance of riming as transfer mechanism of pollutants from the atmosphere into the snow in mixed phase clouds was investigated at the Jungfraujoch (3450 m a.s.l), during two intensive measurement campaigns in April 1992 and in October-November 1993. Cloud water and bulk snow crystal samples were concurrently collected during precipitation events, and were chromatographically analyzed for inorganic ions. The extent of riming was determined from the collection of individual snow crystals on Formvar replicas. Relatively low degrees of riming were observed during all the events. The rimed mass fraction (RMF) was being used as a tool to determine the role of riming with respect to other scavenging processes. No significant difference between the early-spring and the early-winter events was found. The precipitation events were classified on the basis of the temporal changes of the number concentration of aerosol particles and the equivalent potential temperature during an event. When the site could be considered as a "closed system", meaning that there was no air mass change, and that all the physical processes were occurring in the air mass being sampled at the site, then a strong positive correlation between the RMF and the concentration ratios, R, of snow water to cloud water was found. In contrast, a lack of statistical correlation between the RMF and the ratios R was observed when the sampling site was an "open system", meaning that it was affected by the entrainment of a new air mass. The application of a simple physical scheme revealed that a linear relationship between RMF and R is expected, provided that the cloud water samples are representative of the air mass in which the snow crystals are generated. Further modification of this scheme provided a relationship for the assessment of the importance of riming as transfer mechanism. The riming process was found to be responsible for 82 (±17) % of Cl -, 49 (±31) % of NO- 3, 77 (±20) % of SO 2-4, 82 (±16

  16. Factors affecting the reading of rimes in words and nonwords in beginning readers with cognitive disabilities and typically developing readers: explorations in similarity and difference in word recognition cue use.

    PubMed

    Calhoon, J A

    2001-10-01

    The exploratory research reported in this study was designed to initiate research in reading that includes children who have cognitive disabilities other than learning disabilities. Forty children, whose word recognition level was at the second-grade level, were assessed for knowledge of letter names, letter sounds, and rime recognition for high and low frequency target words and nonwords. Of these children, 20 were typically developing children and 20 were children with cognitive disabilities broadly defined. Both groups of children were found to be more similar than dissimilar in their rime-recognition accuracy, miscues, and graphemephoneme knowledge. In general, results proved to be more heuristic than concrete.

  17. Large grain instruction and phonological awareness skill influence rime sensitivity, processing speed, and early decoding skill in adult L2 learners

    PubMed Central

    Brennan, Christine; Booth, James R.

    2016-01-01

    Linguistic knowledge, cognitive ability, and instruction influence how adults acquire a second orthography yet it remains unclear how different forms of instruction influence grain size sensitivity and subsequent decoding skill and speed. Thirty-seven monolingual, literate English-speaking adults were trained on a novel artificial orthography given initial instruction that directed attention to either large or small grain size units (i.e., words or letters). We examined how initial instruction influenced processing speed (i.e., reaction time (RT)) and sensitivity to different orthographic grain sizes (i.e., rimes and letters). Directing attention to large grain size units during initial instruction resulted in higher accuracy for rimes, whereas directing attention to smaller grain size units resulted in slower RTs across all measures. Additionally, phonological awareness skill modulated early learning effects, compensating for the limitations of the initial instruction provided. Collectively, these findings suggest that when adults are learning to read a second orthography, consideration should be given to how initial instruction directs attention to different grain sizes and inherent phonological awareness ability. PMID:27829705

  18. Large grain instruction and phonological awareness skill influence rime sensitivity, processing speed, and early decoding skill in adult L2 learners.

    PubMed

    Brennan, Christine; Booth, James R

    2015-09-01

    Linguistic knowledge, cognitive ability, and instruction influence how adults acquire a second orthography yet it remains unclear how different forms of instruction influence grain size sensitivity and subsequent decoding skill and speed. Thirty-seven monolingual, literate English-speaking adults were trained on a novel artificial orthography given initial instruction that directed attention to either large or small grain size units (i.e., words or letters). We examined how initial instruction influenced processing speed (i.e., reaction time (RT)) and sensitivity to different orthographic grain sizes (i.e., rimes and letters). Directing attention to large grain size units during initial instruction resulted in higher accuracy for rimes, whereas directing attention to smaller grain size units resulted in slower RTs across all measures. Additionally, phonological awareness skill modulated early learning effects, compensating for the limitations of the initial instruction provided. Collectively, these findings suggest that when adults are learning to read a second orthography, consideration should be given to how initial instruction directs attention to different grain sizes and inherent phonological awareness ability.

  19. Influence du traitement ionisant par rayonnement γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale

    NASA Astrophysics Data System (ADS)

    Stuyck, S.; Connaulte, J.; Lesgards, G.; Prost, M.; Raffi, J.

    1998-04-01

    Ionizing radiation of vegetables is a cleaning up and preservation physical treatment which consists in submitting them to γ radiation, X radiation or electrons beam. This study deals with the influence of γ radiation on antioxidative effect of vegetables polyphenolic parts. In that purpose, we use a simple biological test based on erythrocytes haemolysis. Le traitement ionisant des produits végétaux est un procédé physique d'assainissement et de conservation qui consiste à les soumettre à l'action de rayonnements γ, de rayons X ou de faisceaux d'électrons. Ce travail porte sur l'étude de l'influence des rayonnements γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale. Pour cela, un test biologique basé sur l'hémolyse d'érythrocytes est utilisé.

  20. Development of a Gd(III)-based receptor-induced magnetization enhancement (RIME) contrast agent for β-glucuronidase activity profiling.

    PubMed

    Chen, Shih-Hsien; Kuo, Yu-Ting; Singh, Gyan; Cheng, Tian-Lu; Su, Yu-Zheng; Wang, Tzu-Pin; Chiu, Yen-Yu; Lai, Jui-Jen; Chang, Chih-Ching; Jaw, Twei-Shiun; Tzou, Shey-Cherng; Liu, Gin-Chung; Wang, Yun-Ming

    2012-11-19

    β-Glucuronidase is a key lysosomal enzyme and is often overexpressed in necrotic tumor masses. We report here the synthesis of a pro receptor-induced magnetization enhancement (pro-RIME) magnetic resonance imaging (MRI) contrast agent ([Gd(DOTA-FPβGu)]) for molecular imaging of β-glucuronidase activity in tumor tissues. The contrast agent consists of two parts, a gadolinium complex and a β-glucuronidase substrate (β-d-glucopyranuronic acid). The binding association constant (KA) of [Gd(DOTA-FPβGu)] is 7.42 × 10(2), which is significantly lower than that of a commercially available MS-325 (KA = 3.0 × 10(4)) RIME contrast agent. The low KA value of [Gd(DOTA-FPβGu)] is due to the pendant β-d-glucopyranuronic acid moiety. Therefore, [Gd(DOTA-FPβGu)] can be used for detection of β-glucuronidase through RIME modulation. The detail mechanism of enzymatic activation of [Gd(DOTA-FPβGu)] was elucidated by LC-MS. The kinetics of β-glucuronidase catalyzed hydrolysis of [Eu(DOTA-FPβGu)] at pH 7.4 best fit the Miechalis-Menten kinetic mode with Km = 1.38 mM, kcat = 3.76 × 10(3), and kcat/Km = 2.72 × 10(3) M(-1) s(-1). The low Km value indicates high affinity of β-glucuronidase for [Gd(DOTA-FPβGu)] at physiological pH. Relaxometric studies revealed that T1 relaxivity of [Gd(DOTA-FPβGu)] changes in response to the concentration of β-glucuronidase. Consistent with the relaxometric studies, [Gd(DOTA-FPβGu)] showed significant change in MR image signal in the presence of β-glucuronidase and HSA. In vitro and in vivo MR images demonstrated appreciable differences in signal enhancement in the cell lines and tumor xenografts in accordance to their expression levels of β-glucuronidase.

  1. Caractérisation du seuil d'ablation des parois dans les sources de rayonnement EUV par décharge capillaire

    NASA Astrophysics Data System (ADS)

    Sarroukh, O.; Robert, E.; Kaiser, J.; Viladrosa, R.; Pouvesle, J. M.; Fleurier, C.; Cachoncinlle, C.

    2005-06-01

    Les sources de rayonnement Extrême Ultraviolet (EUV) par décharge capillaire connaissent un intérêt de plus en plus considérable pour de nombreuses applications scientifiques et technologiques. Au GREMI, nous étudions le fonctionnement des sources de rayonnement EUV émettant à 13.5 nm pouvant répondre à certaines applications liées à la nouvelle génération de la lithographie. Ces sources pulsées, nommées CAPELLA, ATλ AS et PROXIMA, sont basées sur une décharge capillaire en flux de gaz. Ce type de décharge produit un plasma chaud, dense et fortement ionisé émettant dans la gamme spectrale de l'EUV. En effet, les températures électroniques peuvent atteindre des dizaines d'électronvolts et les densités électroniques sont de l'ordre de 1017 cm-3. Les échanges thermiques entre le plasma ainsi créé et les parois du capillaire peuvent être suffisamment important pour que les parois du capillaire soient ablatées. Cette ablation peut être plus ou moins importante selon la densité d'énergie injectée dans le capillaire. Des mesures spectroscopiques du plasma émetteur dans les gammes spectrales de l'UV et l'EUV ont montré la présence d'un seuil d'ablation situé autour de à 350 J.cm-3. Nous utilisons un modèle thermique présenté [1] pour modéliser l'évolution temporelle de la température des parois du capillaire. Le seuil peut être ainsi estimé. Les résultats expérimentaux obtenus à partir de nos mesures spectroscopiques sont comparés ensuite aux résultats numériques.

  2. Etude du Photochromisme et de la Photorefractivite dans le Poly

    NASA Astrophysics Data System (ADS)

    Ghailane, Fatima

    1995-11-01

    Nous avons etudie la possibilite d'utiliser un materiau organique, le poly(vinylcarbazole) comme milieu de stockage optique de masse en temps reel. Ce materiau dope aux photochromes presente un potentiel non negligeable pour l'holographie de volume en temps reel. Plusiers cycles, Ecriture-Lecture-Effacement, ont ete enregistres dans cette matrice polymerique avec une resolution assez elevee. Une etude a ete menee afin d'obtenir la valeur des parametres comme l'epaisseur du film et l'intensite d'ecriture pour un angle d'enregistrement theta_{ acute ecriture} donne qui permettent d'obtenir les meilleures efficacites diffractionelles tout en preservant ce milieu de tout effet de fatigue ou de degradation. Ce polymere devient photorefractif une fois melange avec un bon accepteur de charge, le trinitrofluorenone et un bon chromophore non-lineaire, le disperse orange 25. Nous avons etudie experimentalement la conductivite en obscurite et la photoconductivite de ce materiau. Des simulations numeriques ont ete realisees en se basant sur le modele de Poole-Frenkel. Nous avons aussi etudie l'implantation de faisceaux d'ions d'oxygene d'energie 200 keV pour inscrire dans le PVCz un guide d'onde plan a profil d'indice. Une etude ESCA complete cette partie afin de savoir les modifications induites par implementation ionique a l'interieur du film polymerique.

  3. Cu-Zn isotope constraints on the provenance of air pollution in Central Europe: Using soluble and insoluble particles in snow and rime.

    PubMed

    Novak, Martin; Sipkova, Adela; Chrastny, Vladislav; Stepanova, Marketa; Voldrichova, Petra; Veselovsky, Frantisek; Prechova, Eva; Blaha, Vladimir; Curik, Jan; Farkas, Juraj; Erbanova, Lucie; Bohdalkova, Leona; Pasava, Jan; Mikova, Jitka; Komarek, Arnost; Krachler, Michael

    2016-11-01

    Copper (Cu) and zinc (Zn) isotope ratios can be used to fingerprint sources and dispersion pathways of pollutants in the environment. Little is known, however, about the potential of δ(65)Cu and δ(66)Zn values in liquid and solid forms of atmospheric deposition to distinguish between geogenic, industrial, local and remote sources of these potentially toxic base metals. Here we present Cu-Zn deposition fluxes at 10 mountain-top sites in the Czech Republic, a region affected by extremely high industrial emission rates 25 years ago. Additionally, we monitored isotope composition of Cu and Zn in vertical and horizontal atmospheric deposition at two sites. We compared δ(65)Cu and δ(66)Zn values in snow and rime, extracted by diluted HNO3 and concentrated HF. Cu and Zn isotope signatures of industrial pollution sources were also determined. Cu and Zn deposition fluxes at all study sites were minute. The mean δ(65)Cu value of atmospheric deposition (-0.07‰) was higher than the mean δ(65)Cu value of pollution sources (-1.17‰). The variability in δ(65)Cu values of atmospheric deposition was lower, compared to the pollution sources. The mean δ(66)Zn value of atmospheric deposition (-0.09‰) was slightly higher than the mean δ(66)Zn value of pollution sources (-0.23‰). The variability in δ(66)Zn values of atmospheric deposition was indistinguishable from that of pollution sources. The largest isotope differences (0.35‰) were observed between the insoluble and soluble fractions of atmospheric deposition. These differences may result from different sources of Cu/Zn for each fraction. The difference in isotope composition of soluble and insoluble particles appears to be a promising tool for pollution provenance studies in Central Europe. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Etude aerodynamique d'un jet turbulent impactant une paroi concave

    NASA Astrophysics Data System (ADS)

    LeBlanc, Benoit

    Etant donne la demande croissante de temperatures elevees dans des chambres de combustion de systemes de propulsions en aerospatiale (turbomoteurs, moteur a reaction, etc.), l'interet dans le refroidissement par jets impactant s'est vu croitre. Le refroidissement des aubes de turbine permet une augmentation de temperature de combustion, ce qui se traduit en une augmentation de l'efficacite de combustion et donc une meilleure economie de carburant. Le transfert de chaleur dans les au bages est influence par les aspects aerodynamiques du refroidissement a jet, particulierement dans le cas d'ecoulements turbulents. Un manque de comprehension de l'aerodynamique a l'interieur de ces espaces confinees peut mener a des changements de transfert thermique qui sont inattendus, ce qui augmente le risque de fluage. Il est donc d'interet pour l'industrie aerospatiale et l'academie de poursuivre la recherche dans l'aerodynamique des jets turbulents impactant les parois courbes. Les jets impactant les surfaces courbes ont deja fait l'objet de nombreuses etudes. Par contre des conditions oscillatoires observees en laboratoire se sont averees difficiles a reproduire en numerique, puisque les structures d'ecoulements impactants des parois concaves sont fortement dependantes de la turbulence et des effets instationnaires. Une etude experimentale fut realisee a l'institut PPRIME a l'Universite de Poitiers afin d'observer le phenomene d'oscillation dans le jet. Une serie d'essais ont verifie les conditions d'ecoulement laminaires et turbulentes, toutefois le cout des essais experimentaux a seulement permis d'avoir un apercu du phenomene global. Une deuxieme serie d'essais fut realisee numeriquement a l'Universite de Moncton avec l'outil OpenFOAM pour des conditions d'ecoulement laminaire et bidimensionnel. Cette etude a donc comme but de poursuivre l'enquete de l'aerodynamique oscillatoire des jets impactant des parois courbes, mais pour un regime d'ecoulement transitoire, turbulent

  5. Analyse de l'intensité de fluorescence émise par une multicouche périodique sous rayonnement synchrotron. Application à l'étude de la répartition spatiale des éléments dans l'empilement

    NASA Astrophysics Data System (ADS)

    Bridou, F.; Cauchon, G.; Idir, M.

    2004-11-01

    L'analyse de l'intensité du rayonnement de fluorescence des multicouches périodiques en fonction des angles d'incidence ou d'émission, peut constituer une méthode de caractérisation non destructive capable de déterminer le profil de concentration en profondeur d'un élément donné, notamment au niveau des interfaces où ce profil influe considérablement sur les performances optiques dans le domaine X-UV. Le principe de la méthode consiste à exciter la fluorescence d'un des deux matériaux de l'empilement par une radiation d'énergie supérieure à celle du seuil d'absorption de l'élément considéré. Celui-ci va émettre son propre rayonnement à l'intérieur de la multicouche. La répartition d'intensité est modulée selon la distribution géométrique des sources de rayonnement (donc de l'élément excité) à l'intérieur de l'empilement. On présente ici les résultats qui ont pu êtres obtenus à partir du rayonnement d'une source synchrotron (SB3_LURE) pour étudier une multicouche Mo/Si de 50 périodes. On a pu ainsi exciter d'une part la fluorescence du silicium, puis celle du molybdène, et montrer que les informations obtenues sur la répartition des éléments dans la multicouche étaient complémentaires.

  6. Etude sur les tendons en materiaux composites et leur application aux ancrages postcontraints

    NASA Astrophysics Data System (ADS)

    Chennouf, Adil

    L'objectif general de la presente these est d'evaluer le comportement a l'arrachement et au fluage d'ancrages injectes constitues de tendons en materiaux composites afin d'etablir des recommandations plus appropriees et realistes pour le dimensionnement et la conception. Quatre types de tendons en materiaux composites, deux a base de fibres d'aramide et deux a base de fibres de carbone, ont ete utilises dans l'etude. Les travaux de recherche de cette these ont porte notamment sur: (I) Une caracterisation physique et mecanique des tendons en materiaux composites utilises dans l'etude. (II) Une etude en laboratoire sur les coulis de scellement. La premiere etape de cette etude a concerne le developpement d'un coulis de scellement performant adapte aux tendons en materiaux composites et a differentes situations d'injection. La seconde etape a traite des essais de caracterisations physique et mecanique du coulis de scellement developpe comparativement a trois coulis de scellement usuels d'un meme rapport E/L de 0,4. (III) Une etude sur des modeles reduits d'ancrages injectes. (IV) Une etude sur des modeles d'ancrages a grande echelle. La synthese de ces etudes a permis d'enoncer les principales conclusions suivantes: (1) Les valeurs moyennes des charges de rupture des tendons en materiaux composites ont ete de 1% a 29% superieures a celles specifiees par les manufacturiers. (2) L'etude sur les coulis de scellement a permis le developpement de coulis de ciment repondant aux criteres fixes, soient une grande stabilite, une bonne fluidite, une legere expansion et de bonnes caracteristiques mecaniques. (3) Les tendons en materiaux composites ont montre des contraintes d'adherence maximum superieures a celles des tendons en acier. (4) Le type de fibre, la configuration et le fini de surface des tendons en materiaux composites gouvernent leur resistance a l'adherence. (5) L'introduction de sable et d'autres ajouts comme les fines de silice et la poudre d'aluminium au coulis

  7. Singing as a Therapeutic Agent, inThe Etude, 1891-1949.

    PubMed

    Hunter

    1999-01-01

    The Etude music magazine, founded by Theodore Presser, was one of a number of popular music magazines published in the years prior to the establishment of the music therapy profession in 1950. During its publication run from 1883 to 1957, over 100 music therapy related articles appeared, including 13 on the health benefits of singing published between 1891 and 1949. Written by authors with diverse backgrounds, such as the famous Battle Creek, Michigan physician John Harvey Kellogg and Boston music critic Louis C. Elson, the articles contained consistent and adamant support regarding the health benefits of singing. The advantages described were both physical and psychological, and were recommended prophylactically for well persons and therapeutically for ill persons. Although the articles varied in perspective, from philosophical to theoretical to pedagogical, there is a consistent holistic medicine theme that appeared almost ahead of its time and no doubt linked to the push for vocal music education in that era. The importance of The Etude in promulgating ideas that helped shape the early practice of music therapy should not be underestimated. For much of its publication run The Etude was the largest music periodical in print, reaching its peak circulation of 250,000 copies per month in 1924.

  8. Etude theorique des fluctuations structurales dans les composes organiques a dimensionnalite reduite

    NASA Astrophysics Data System (ADS)

    Dumoulin, Benoit

    Les systemes a dimensionnalite reduite constituent maintenant une branche entiere de la physique de la matiere condensee. Cette derniere s'est developpee rapidement au cours des dernieres annees, avec la decouverte des materiaux organiques qui presentent, justement, des proprietes physiques fortement anisotropes. Cette these presente une etude en trois parties de plusieurs composes organiques qui, bien que tres differents du point de vue de leurs compositions chimiques et de leurs proprietes physiques a haute temperature, subissent tous une instabilite structurale a tres basse temperature. De plus, dans chacun des cas, l'instabilite structurale est precedee d'un important regime fluctuatif a partir duquel les proprietes physiques changent de maniere significative. Notre etude suit un ordre chronologique inverse puisque nous nous attardons en premier lieu au cas de composes recemment decouverts: les composes de la famille des (BCPTTF)2X (X = PF6 , AsF6). Ces derniers sont des isolants magnetiques a la temperature ambiante et subissent une instabilite structurale de type spin-Peierls a une temperature appelee TSP. En particulier, nous nous interessons a l'etude des proprietes physiques de ces systemes dans le regime fluctuatif, qui precede cette instabilite. Notre etude theorique nous permet de comprendre en detail comment ces systemes s'approchent de l'instabilite struturale. Dans la seconde partie de cette these, nous etudions le regime fluctuatif (pre-transitionnel) observe experimentalement dans le compose de (TMTTF)2PF6. Ce compose organique, dont la structure s'apparente aux sels de Bechgaard, subit une instabilite de type spin-Peierls a une temperature T SP = 19K. Bien que ce compose possede la particularite d'etre un bon conducteur a la temperature ambiante, il subit une transition de type Mott-Hubbard a une temperature Trho ≈ 220K et devient alors un isolant magnetique, analogue aux composes de la famille des (BCPTTF)2X. Le regime fluctuatif precedant l

  9. Etude des émissions radio aurorales de Saturne, modélisation et aurores UV

    NASA Astrophysics Data System (ADS)

    Lamy, Laurent

    2008-09-01

    Cette thèse porte sur l'étude du rayonnement radio auroral kilométrique de Saturne (SKR pour Saturn Kilometric Radiation) observé de façon quasi-continue par les antennes radio de la sonde Cassini depuis son entrée en orbite autour de Saturne en juillet 2004. Comme les rayonnements radio auroraux des autres planètes magnétisées, le SKR est généré sur des lignes de champ magnétique de haute latitude prés des pôles magnétiques. Tirant parti de plusieurs années d'observations, les propriétés macroscopiques du SKR (spectre, polarisation, conjuguaison des sources de chaque hémisphère, mode d'émission) sont déduites par une analyse statistique. Elles montrent en particulier que les caractéristiques de l'émission dépendent fortement de la position de l'observateur. Ceci est une conséquence directe de l'anisotropie du SKR qui engendre de forts effets de visibilité, visibles dans les cartes d'intensité temps-fréquence (arcs, régions d'invisibilité de l'émission). La simulation de ces effets de visibilité apporte de nouvelles contraintes sur les propriétés microscopiques des sources (énergie et distribution des électrons auroraux). Le SKR est connu pour être modulé à une période variable. Une analyse de la variation de cette période radio sur plusieurs années révèle des oscillations à court terme de l'ordre de 20-30 jours dont l'origine est attribuée à la variation de la vitesse caractéristique du vent solaire au niveau de Saturne. Une étude parallèle du rayonnement auroral kilométrique terrestre (AKR), observé lors du survol de la Terre par Cassini en août 1999, met en évidence la découverte d'une modulation diurne semblable à celle du SKR. Enfin, la technique de goniopolarimétrie permet de faire de l'imagerie radio des sources du SKR. L'étude de leur distribution moyenne montre pour la première fois l'existence d'un ovale radio. La comparaison des images des sources du SKR avec celles des ovales auroraux (observ

  10. Contributions a L'etude de Dispositifs D'optique Integree

    NASA Astrophysics Data System (ADS)

    Touam, Tahar

    Cette these contient des contributions a l'etude de deux champs du vaste domaine de l'optique integree. A cet effet, nous avons divise notre travail en deux grandes parties:. Dans une premiere partie, nous traitons le probleme de la realisation d'une nouvelle classe de guides d'onde planaires utilisables dans le domaine de longueur d'onde de l'infrarouge moyen (infrarouge thermique), domaine ou l'apparition anticipee de fibres optiques a pertes extremement faibles rendraient fort interessante l'existence de tels guides d'onde planaires. Dans un premier temps, nous presentons une etude analytique originale d'une structure planaire a profil d'indice gradue, suivie d'une analyse d'un guide canal base sur cette structure. Dans un deuxieme temps, nous decrivons le procede de fabrication par pulverisation atomique d'un guide planaire forme d'arseniure de gallium (AsGa) sur du dioxyde de silicium (SiO_2 ), combinaison de materiau compatible avec l'infrarouge moyen. Finalement, nous presentons une etude de conception d'un reseau de surface destine a coupler la lumiere dans un tel guide, les autres methodes traditionnelles de couplage semblant peu appropriees aux environs de lambda = 10 mum. Dans une deuxieme partie, nous traitons le probleme de la jonction Y en optique integree, jonction qui soufre de pertes tres importantes des que l'angle d'ouverture devient interessant pour le concepteur de circuits integres optiques. L'analyse est basee sur la methode numerique dite BPM (Beam Propagation Method; methode de propagation du faisceau) qui fait l'objet d'un bref rappel. Nous poursuivons avec l'etude et l'optimisation d'une nouvelle jonction Y dont l'essence est l'utilisation du phenomene de diffraction a travers trois fentes de phase. Nous obtenons ainsi une tres bonne jonction, separant proprement le faisceau, a une ouverture de 10 degres. Finalement, nous faisons un rappel d'un profil d'indice dit "ideal" pour guides courbes et nous proposons l'utilisation de tels guides

  11. Etude des chaines de spins par les methodes de la theorie quantique des champs

    NASA Astrophysics Data System (ADS)

    Allen, Dave

    Notre etude porte sur la chaine de spins en zigzag avec dimerisation dans le cas des spins 1/2 et 1. L'echelle de spin ordinaire et la chaine en zigzag simple en sont des cas particuliers. Dans la limite continue, ces systemes sont decrits par des modeles Wess-Zumino-Witten couples. Afin de pouvoir calculer les fonctions de correlation, nous exposons differentes equivalences quantiques permettant de simplifier les calculs. Dans le cas de chaines de spin 1/2, nous demontrons l'equivalence avec un modele de type Gross-Neveu, en fonction de fermions de Majorana; ces fermions decrivent alors les excitations elementaires du systeme. Nous exposons une vision classique de ces excitations afin de voir les mecanismes de confinement des spinons. Dans le cas de chaines de spin 1, l'etude est plus complexe. Nous pouvons decrire le systeme a l'aide de modeles sine-Gordon perturbes par de nombreuses interactions. En se limitant aux plus importantes, nous pouvons expliquer le comportement du gap en fonction du couplage interchaine observe numeriquement.

  12. Overview of ICF program at Centre D{close_quote}Etudes de Limeil-Valenton

    SciTech Connect

    Cel-V Laser Team

    1996-05-01

    The major objectives of the CEA-DAM laser program is to determine the various requirements to achieve thermonuclear fusion in laboratory. We report here recent results obtained at Centre d{close_quote}Etudes de Limeil-Valenton on high density X-Ray implosions, radiative transfer processes, hydrodynamic instabilities and laser-plasma interaction involved in cavity physics. Ignition and a moderate gain appears to be achievable with a laser energy of about 1.5{minus}2 MJ delivered at {lambda}=0, 35 {mu}m with a shaped pulse (duration{approximately}16 ns). The construction of such a laser is realizable and a conceptual design is under preparation. {copyright} {ital 1996 American Institute of Physics.}

  13. Etudes Asymptotiques en Filtrage Non Lineaire Avec Petit Bruit D’Observation (Asymptotic Studies in Nonlinear Time Filtering with Small Observation Noise)

    DTIC Science & Technology

    1990-09-26

    titre de s DOCTEUR DE L’UNIVERSITE DE PROVENCE : SpdcialitM MATHEMATIQUES APPLIQUEES par PAULA M. L. P. MILHEIRO de OLIVEIRA Sujet de la these: ETUDES...PROVENCE Spdcialitd: MATHEMATIQUES APPLIQUEES par PAULA M. L. P. MILHEIRO de OLIVEIRA Sujet dela thse: E~TUDES ASYMPTOTIQUES EN FILTRAGE NON LINEAIRE...At Pk + h2 At p,]f6 2 ± h2 AtP] k CO lk + Ilk Donc C I~k+1 Pk1 (10) 1-iPk + C Cl Suivant un raisonnement par recurrence on trouve l’expression: Ilk_

  14. Etude paleomagnetique des sediments holocenes de la Fosse du Mackenzie, mer de Beaufort

    NASA Astrophysics Data System (ADS)

    Barris, Elissa

    Les etudes paleomagnetiques a haute resolution sont d'importance en magnetostratigraphie et geomagnetisme, particulierement dans l'Arctique en raison de l'inaccessibilite et des faibles vitesses de sedimentation dans plusieurs secteurs. Deux carottes sedimentaires representant l'Holocene recent ont ete recoltees dans la Fosse du Mackenzie, une region avec des vitesses de sedimentation relativement elevees. Une carotte boite et un Calypso square core ont ete preleves a deux sites (690 et 680). Les proprietes physiques et magnetiques et la granulometrie ont ete mesurees, ainsi que les aimantations remanentes naturelle, anhysteretique, isothermale et isothermale saturee (NRM, ARM, IRM et SIRM). L'hysteresis magnetique indique une forte concentration de magnetite de type pseudo-single domain, un porteur ideal de remanence, alors que les mesures de la susceptibilite magnetique suggerent une concentration uniforme. Les valeurs de deviation angulaire maximale (MAD) et du champ median destructif (MDF) indiquent des donnees de direction d'excellente qualite et une coercivite typique de la magnetite, respectivement. Finalement, dans la carotte 690 et la partie intermediaire de la 680, l'inclinaison vane autour des valeurs d'un dipole axial geocentrique (GAD) pour la latitude des sites, renforcant la fiabilite du signal paleomagnetique. Finalement, des proxies de la paleointensite relative ont ete construits pour les carottes 690 et 680 en normalisant la NRM par l'IRM et l'ARM, respectivement. Vingt-et-une coquilles de pelecypodes reparties dans les deux carottes ont ete recoltees pour construire un modele d'âge au radiocarbone a chaque si te, une tâche necessaire pour la mise en contexte d'un enregistrement paleomagnetique, mais souvent difficile dans l'Arctique. En utilisant ces modeles d'âge, les enregistrements paleomagnetiques ont ete compares avec d'autres provenant du bas-Arctique et des moyennes latitudes, soulignant leur potentiel pour des etudes

  15. Long homozygous chromosomal segments in reference families from the centre d'Etude du polymorphisme humain.

    PubMed

    Broman, K W; Weber, J L

    1999-12-01

    Using genotypes from nearly 8,000 short tandem-repeat polymorphisms typed in eight of the reference families from the Centre d'Etude du Polymorphisme Humain (CEPH), we identified numerous long chromosomal segments of marker homozygosity in many CEPH individuals. These segments are likely to represent autozygosity, the result of the mating of related individuals. Confidence that the complete segment is homozygous is gained only with markers of high density. The longest segment in the eight families spanned 77 cM and included 118 homozygous markers. All individuals in family 884 showed at least one segment of homozygosity: the father and mother were homozygous in 8 and 10 segments with an average length of 13 and 16 cM, respectively, and covering a total of 105 and 160 cM, respectively. The progeny in family 884 were homozygous over 5-16 segments with average length 11 cM. The progeny in family 102 were homozygous over 4-12 segments with average length 19 cM. Of the 100 individuals in the other six families, 1 had especially long homozygous segments, and 19 had short but significant homozygous segments. Our results indicate that long homozygous segments are common in humans and that these segments could have a substantial impact on gene mapping and health.

  16. Gastrointestinal lymphomas: the French experience of the Groupe D'etude des Lymphomes Digestifs (GELD).

    PubMed

    Ruskoné-Fourmestraux, A

    2000-01-01

    Since 1983, the French Groupe d'Etude des Lymphomes Digestifs (GELD), under the aegis of the Fondation Française de Cancérologie Digestive, has aimed to identify the different prognostic groups of the primary digestive-tract lymphomas (PDTL) and their optimal treatment. Successive multicenter studies were conducted and 91 PDTL were evaluated. A marked improvement in their prognosis was obtained by a strategy including precise histologic typing and clinical staging followed by a therapeutic approach combining initial surgical resection, whenever possible or reasonable, followed by chemotherapy adapted to the grade of malignancy and resectability of the lymphoma. The multivariate analysis indicated that the factors for good prognosis were age (< 65 yrs), gastric localisation, stage IE and radical or even incomplete surgery. However, Helicobacter pylori eradication should be the first treatment in stage IE low-grade gastric mucosa-associated lymphoid tissue (MALT) tumors. The long-term results of such medical treatment are evaluated together with the management and the place of surgery in these localised tumors. However, owing to the limited number of patients, a large international co-operative trial is needed to confirm the findings. Thirty-one cases of multiple lymphomatous polyposis were also collected and confirmed to be a distinct entity among PDTL and the gastrointestinal counterpart of the mantle-cell-zone lymphomas. High-dose radio-chemotherapy supported by auto-transplantation improved their prognosis.

  17. Etude vibroacoustique d'un systeme coque-plancher-cavite avec application a un fuselage simplifie

    NASA Astrophysics Data System (ADS)

    Missaoui, Jemai

    L'objectif de ce travail est de developper des modeles semi-analytiques pour etudier le comportement structural, acoustique et vibro-acoustique d'un systeme coque-plancher-cavite. La connection entre la coque et le plancher est assuree en utilisant le concept de rigidite artificielle. Ce concept de modelisation flexible facilite le choix des fonctions de decomposition du mouvement de chaque sous-structure. Les resultats issus de cette etude vont permettre la comprehension des phenomenes physiques de base rencontres dans une structure d'avion. Une approche integro-modale est developpee pour calculer les caracteristiques modales acoustiques. Elle utilise une discretisation de la cavite irreguliere en sous-cavites acoustiques dont les bases de developpement sont connues a priori. Cette approche, a caractere physique, presente l'avantage d'etre efficace et precise. La validite de celle-ci a ete demontree en utilisant des resultats disponibles dans la litterature. Un modele vibro-acoustique est developpe dans un but d'analyser et de comprendre les effets structuraux et acoustiques du plancher dans la configuration. La validite des resultats, en termes de resonance et de fonction de transfert, est verifiee a l'aide des mesures experimentales realisees au laboratoire.

  18. Etude de la photosensibilite dans la silice implantee avec des ions de haute energie

    NASA Astrophysics Data System (ADS)

    Verhaegen, Marc

    La photosensibilite est la propriete par laquelle une materiau donne voit son indice de refraction changer sous l'effet d'une exposition lumineuse. Malgre le nombre croissant de dispositif base sur ce phenomene, les mecanismes a la base de la photosensibilite sont encore debattus. Nous apportons dans cette these un eclairage original sur ce sujet en etudiant la matrice de silice pure non dopee rendue photosensible par implantation d'ion de haute energie. L'implantation d'ions silicium de S MeV modifie l'indice de refraction principalement en densifiant une couche mince dont l'epaisseur est de l'ordre de quelques microns. Nos mesures montrent qu'un guide plan supportant les modes TEi et TMi (i = 0,1) est forme et que l'indice effectif du mode TE0 suit l'evolution de la densification en fonction de la dose de silicium implantee. Nous montrerons egalement que l'augmentation d'indice et la densification produites par implantation atteignent un palier pour une dose de 3 x 1014Si/cm 2, alors que la production de defauts par implantation atteint son palier pour une dose plus faible d'un ordre de grandeur soit 3 x 1013Si/cm2. Le profil d'indice longitudinal produit par l'implantation ionique est calcule a partir des mesures des indices effectifs des modes guides. Ce profil suggere que l'augmentation d'indice comprend une contribution dues collisions et une contribution dues aux pertes d'energie par ionisation. La contribution des pertes par ionisation influence significativement le profil d'indice pour des valeurs de pertes d'energie par unite de longueur (dE/dx) de l'ordre de 2 keV/nm. Lorsque la silice implantee est soumise a un rayonnement ultraviolet d'un laser a excimeres, il en resulte une diminution d'indice de refraction de l'ordre de 10-3 avec une efficacite plus grande si la longueur d'onde d'exposition est 193nm (ArF) plutot que 248nm (KrF). Deux regimes d'exposition lumineuse de la silice implantee a 193nm sont observes. Le premier regime produit une diminution

  19. La recombinaison et le rayonnement cosmologique

    NASA Astrophysics Data System (ADS)

    Priou, Denis

    2017-03-01

    The last scattering and the recombination epoch, which occurred approximately 380 000 years after the Big Bang, was followed by a period of time, referred to as "dark ages", during which the first stars and the first galaxies were formed in an expanding, dark universe. During nearly 250 millions years, very specific physical processes were possible, due to the interaction between the spin of the proton and the spin of the electron in neutral hydrogen atoms : a phenomenon called "spin flip" could trigger transitions in the hydrogen atoms, resulting in the emission or the absorption of electromagnetic radiation at the specific wavelength of 21,1cm. Four energetic reservoirs are involved to explain the evolution of the Universes during the dark ages : the cosmic microwave background, the kinetic energy of hydrogen atoms, the hyperfine strcuture of the hydrogem atom and the energy produced by the first stars. In this paper is sketched the history of the Universe during the dark ages, the physical processes involved during its main epochs and their observational consequences. The main astronomical observatories dedicated to the detection of these physical processes are presented.

  20. Etude theorique et experimentale des evaporateurs de dioxyde de carbone operant dans des conditions de givrage

    NASA Astrophysics Data System (ADS)

    Bendaoud, Adlane Larbi

    Les evaporateurs de refrigeration sont surtout du type tube a ailettes, appeles serpentins, et fonctionnent dans l'une des conditions suivantes: seche, humide ou avec formation de givre. Il a ete demontre que la formation du givre sur la paroi exterieure de l'echangeur engendre une surconsommation energetique a cause des operations de degivrage puisque 15 a 20% seulement de la chaleur produite sert au degivrage tandis que le reste est dissipee dans l'environnement [1]. Avec l'avenement des nouveaux refrigerants, moins nocifs envers l'environnement, l'industrie du froid se trouve penalisee du fait que peu ou pas de composantes mecaniques (compresseur, pompe, echangeur...etc.) adaptees sont disponibles [3]. Il s'agit pour la communaute des frigoristes de combler ce retard technologique en redeveloppant ces composantes mecaniques afin qu'elles soient adaptees aux nouveaux refrigerants. Dans cette optique, et afin de mieux comprendre le comportement thermique des evaporateurs au CO2 fonctionnant dans des conditions seches, qu'un groupe de chercheurs du CanmetENERGIE avaient lance, en 2000, un programme de R & D. Dans le cadre de programme un outil de simulation des evaporateurs au CO2 a ete developpe et un banc d'essai contenant une boucle secondaire de refrigeration utilisant le CO2 comme refrigerant a ete construit. Comme continuite de ce travail de recherche, en 2006 ce meme groupe de recherche a lance un nouveau projet qui consiste a faire une etude theorique et experimentale des evaporateurs au CO2 operants dans des conditions de givrage. Et, c'est exactement dans le cadre de ce projet que se positionne ce travail de these. Ce travail de recherche a ete entrepris pour mieux comprendre le comportement thermique et hydrodynamique des serpentins fonctionnant dans des conditions de givrage, l'effet des circuits de refrigerant ainsi que celui des parametres geometriques et d'operation. Pour cela, un travail theorique supporte par une etude experimentale a ete effectue

  1. Caracterisation des etats de surface par teledetection infrarouge thermique multispectrale: Contribution a l'etude des conditions de viabilite hivernale

    NASA Astrophysics Data System (ADS)

    Chagnon, Frederic

    La mesure de temperature d'une surface et de son emissivite thermique constitue encore de nos jours, un defi de taille. D'un point de vue microclimatique, la temperature significative d'une surface est celle qui reflete l'etat des echanges energetiques qui y ont lieu. La radiometrie infrarouge thermique permet de lire la temperature de l'interface air-sol pour une couche infiniment petite de la surface (de l'ordre de quelques microns). Dans le cadre d'un systeme d'aide aux decisions en viabilite hivernale, nous avons defini un prototype de station de mesures mobiles. Cette station permet de determiner, avec precision, la temperature radiative de la surface de la chaussee ainsi que de determiner, avec un taux de succes de plus de 65 %, l'etat de cette meme surface. Par la conception de ce prototype, nous avons aborde le principe physique de la mesure de temperature de surface par radiometrie multispectrale infrarouge thermique. Ce travail aura permis d'evaluer une approche standard de mesure a bande spectrale unique (de 8 a 14 mum). Dans la correction de la temperature radiative de surface, nous avons considere trois methodes distinctes. La premiere methode utilisee est celle de l'algorithme TES (Gillespie et al., 1998). Cet algorithme etablit le spectre d'emissivite, puis calcule une temperature de surface corrigee, en tenant compte de la reflexion du rayonnement thermique incident a la surface. La seconde methode consideree est l'indice TISI (Li et al., 1999) qui consiste en un indice d'emissivite relatif independant de la temperature de la surface et qui tient compte du rayonnement incident a la surface. La troisieme methode est un indice de temperature relative (ITR) qui correspond au contraste normalise des temperatures radiatives de surface. L'identification du type de surface a montre un taux de succes de 54,8 % pour les resultats de l'indice ITR, de 51,9 % pour les resultats de l'indice TISI et de 67,3 % pour les resultats de l'algorithme TES. Quant a la

  2. Etude des proprietes electroniques des etats fondamentaux aux facteurs de remplissage entiers dans la bicouche de graphene

    NASA Astrophysics Data System (ADS)

    Lemonde, Marc-Antoine

    Dans ce document, on etudie les proprietes electroniques d'un systeme compose de deux couches de graphene separees par un dielectrique en presence d'un fort champ magnetique perpendiculaire. L'epaisseur du dielectrique est choisie de facon a pouvoir negliger le transfert de charges par effet tunnel. Ce type de systeme est etudie par quelques groupes de recherche dans le principal but de predire et comprendre la formation de condensat de Bose-Einstein d'excitons dont les composants sont des fermions relativistes sans masse [1] [2] [3]. Nous nous interessons a l'effet de l'interaction electron-electron sur les etats fondamentaux de ce systeme et 'a leurs excitations collectives a facteur de remplissage entier. Plus precisement, nous etudions les diagrammes de phase de cette bicouche de graphene sans terme tunnel dans le niveau de Landau n = 0 pour les facteurs de remplissage nu = 1 et nu = 2 dans la limite ou la temperature tend vers zero. Lors de cette etude, nous appuyons les predictions faites par Allan H. MacDonald et Yogesh N. Joglekar a propos de la formation d'un condensat de Bose-Einstein d'excitons pour differentes zones des diagrammes de phase. Nous etudions aussi la relation de dispersion des excitations collectives soutenues par les etats fondamentaux et leur effet sur le systeme. Finalement, nous nous interessons a la conductivite du systeme. Nous demontrons alors les regles de selection pour l'absorption inter-niveaux de Landaux et nous etudions l'effet des modes collectifs sur l'absorption .intrarniveau de Landau, Ce dernier phenomene ressort directement de la forme particuliere du reseau atomique du graphene et nous proposons dans ce document une toute premiere etude de ce concept. Mots-cles : graphene, gaz d'electrons bidimensionnel, effets Hall quantiques, proprietes electroniques, modes collectifs

  3. Etude de la Region de Transition A=130: Structure a Spin Eleve des Noyaux de SAMARIUM-136 et SAMARIUM-138

    NASA Astrophysics Data System (ADS)

    Nadon, Normand

    La structure a haut spin des noyaux pairs-pairs de ^{136}Sm et ^{138}Sm a ete etudiee a l'aide du spectrometre 8pi de Chalk River. Les noyaux etaient produits par une reaction d'ions lourds. La mesure des cascades gamma emises lors de la desexcitation du noyau nous a permis d'etablir le schema de niveaux des noyaux de ^{136 }Sm et ^{138}Sm jusqu'a un spin de 30hbar. Nous avons mis en evidence plusieurs nouvelles bandes rotationnelles. A partir des calculs theoriques CSM (Cranked Shell Model), nous avons identifie les differentes configurations responsables de l'excitation de ces noyaux. Dans ces deux noyaux, on assiste a une competition entre les neutrons provenant du haut de la couche h_{11/2 } et les protons issus du bas de la meme couche. D'autres calculs TRS (Total Routhian Surface) nous ont permis de suivre l'evolution du noyau en fonction de la deformation. Les resultats montrent que ces noyaux se situent dans une region de transition entre une forme allongee et une forme aplatie. D'apres notre etude, meme si les neutrons entrai nent le noyau vers une forme aplatie, la presence des protons stabilise le noyau a une forme triaxiale. De l'experience effectuee sur le noyau de ^{136}Sm, nous avons observe quelques evidences d'une bande superdeformee. Cette bande serait batie sur une configuration a plusieurs quasiparticules impliquant possiblement l'orbitale nu i_ {13/2}. La decouverte de cette bande superdeformee vient corroborer les predictions theoriques. Cependant, une etude plus approfondie devra etre entreprise afin de valider la structure de cette bande.

  4. Etude Exploratoire sur l’Etat de Stress Post-Traumatique dans Deux Unites Operationnelles de l’Armee de Terre (Exploratory Study of the Condition of Post-Traumatic Stress Disorder from Two Operational Units of Ground Forces)

    DTIC Science & Technology

    2006-04-01

    RTO-MP-HFM-134 30 - 1 Etude exploratoire sur l’état de stress post-traumatique dans deux unités opérationnelles de l’armée de terre D ...Leur diagnostic nécessite une démarche active du médecin. L’objectif de l’étude vise à évaluer la fréquence de cette pathologie dans une population...d’inhibition (1). Cette pathologie a fréquemment une évolution chronique. Elle peut être très invalidante. Vallet, D .; Arvers, P. (2006) Etude exploratoire

  5. La structure de l'eau liquide: Une etude thermique par spectroscopie infrarouge

    NASA Astrophysics Data System (ADS)

    Larouche, Pascal

    Le probleme de la structure de l'eau liquide est important car l'eau est le liquide le plus present sur Terre, et complexe, la quete d'un modele precis pour decrire comment fonctionne ce liquide ayant debute des la fin du dix-neuvieme siecle. Cette etude aborde ce probleme en etudiant l'effet de l'augmentation de la temperature sur H2O et D 2O purs a l'aide de la spectroscopie infrarouge. L'intervalle de temperatures scrute est 29--93.1°C. Les spectres enregistres sont des spectres MIR-ATR entre 650 et 6000 cm-1 . L'analyse par facteurs de ces donnees permet de montrer que deux et seulement deux facteurs principaux sont necessaires pour decomposer tous les spectres experimentaux. Ces resultats sont confirmes grace a l'analyse par facteurs de spectres de la region FIR. Par la suite, la transformation en spectres de la partie reelle n et imaginaire k de l'indice de refraction permet de combiner les donnees des regions MIR et FIR. Une fois ce calcul termine, les spectres de transmission complets de H 2O et D2O entre 25 et 90°C sont connus. Ils sont ensuite utilises pour calculer par extrapolation le spectre des especes constituant l'eau liquide, puis leur abondance en fonction de la temperature. L'extrapolation de ces abondances montre que les especes correspondent a des temperatures limites de --18 et 122°C. Par la suite, la decomposition gaussienne des spectres d'especes met en evidence la riche structure de ces objets et permet de demontrer que l'apparent deplacement du massif d'absorption OH (OD) est produit par une variation de l'intensite des bandes et non pas de leur deplacement. L'examen attentif des spectres des especes prouve qu'il n'y a pas de OH libres crees par l'augmentation de la temperature: meme a 93.1°C, chaque molecule possede quatre liens-H. Ces conclusions sont de plus confirmees par une analyse thermodynamique du passage des molecules de la phase solide a la phase gazeuse. Pour diversifier la nature des resultats experimentaux utilises, des

  6. Etude par spectroscopie de Coulomb de points quantiques lateraux individuels et couples

    NASA Astrophysics Data System (ADS)

    Pioro-Ladriere, Michel

    Des points quantiques contenant un nombre discret et variable d'electrons sont formes dans un gaz bi-dimensionnel d'electrons a l'aide de grilles metalliques. Le transport electrique, le blocage de spin et la detection de charge sont employes comme outils spectroscopiques permettant de sonder les proprietes de ces nanostructures. Ces techniques permettent aussi de controler exactement le nombres d'electrons confines dans des points quantiques individuels et couples en utilisant un patron de grille judicieux. Une technique de refroidissement en tension est developpee afin de minimiser les effets parasites du bruit telegraphique. Ce type de bruit de charge deteriore la stabilite des nanostructures laterales par l'activation d'un minuscule courant de fuite entre les grilles et le gaz bi-dimensionnel. Un modele expliquant le role du refroidissement en tension sur le courant de fuite est presente. L'activation du courant de fuite est confirmee par detection de charge. Les effets des interactions entre les electrons pieges dans un point quantique sont ensuite etudies dans un regime ou il est possible de comparer les resulats experimentaux avec ceux obtenus par diagonalisation exacte. L'etude demontre que la phase associee au facteur de remplissage nu = 2 est instable au-dessus d'un nombre critique d'electrons. Cette instabilite est confirmee experimentalement par blocage de spin. On demontre aussi l'existence d'etats correles dans le regime des renversements de spin, associe au passage de la phase nu = 2 a nu = 1. Les etats correles sont identifies par spectroscopie en transport non lineaire. Cette caracterisation du diagramme de phase de points individuels permet de coupler deux points quantiques configures a nu = 2. Pour ce regime, la nanostructure se comporte comme un systeme a deux niveaux pouvant contenir entre un et quatre electrons de valence et ce, meme si le nombre total d'electrons est plus eleve. Les degres de liberte de charge et de spin des deux points

  7. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    NASA Astrophysics Data System (ADS)

    Savard, Stephane

    Les premieres etudes d'antennes a base de supraconducteurs a haute temperature critique emettant une impulsion electromagnetique dont le contenu en frequence se situe dans le domaine terahertz remontent a 1996. Une antenne supraconductrice est formee d'un micro-pont d'une couche mince supraconductrice sur lequel un courant continu est applique. Un faisceau laser dans le visible est focalise sur le micro-pont et place le supraconducteur dans un etat hors-equilibre ou des paires sont brisees. Grace a la relaxation des quasiparticules en surplus et eventuellement de la reformation des paires supraconductrices, nous pouvons etudier la nature de la supraconductivite. L'analyse de la cinetique temporelle du champ electromagnetique emis par une telle antenne terahertz supraconductrice s'est averee utile pour decrire qualitativement les caracteristiques de celle-ci en fonction des parametres d'operation tels que le courant applique, la temperature et la puissance d'excitation. La comprehension de l'etat hors-equilibre est la cle pour comprendre le fonctionnement des antennes terahertz supraconductrices a haute temperature critique. Dans le but de comprendre ultimement cet etat hors-equilibre, nous avions besoin d'une methode et d'un modele pour extraire de facon plus systematique les proprietes intrinseques du materiau qui compose l'antenne terahertz a partir des caracteristiques d'emission de celle-ci. Nous avons developpe une procedure pour calibrer le spectrometre dans le domaine temporel en utilisant des antennes terahertz de GaAs bombarde aux protons H+ comme emetteur et detecteur. Une fois le montage calibre, nous y avons insere une antenne emettrice dipolaire de YBa 2Cu3O7-delta . Un modele avec des fonctions exponentielles de montee et de descente du signal est utilise pour lisser le spectre du champ electromagnetique de l'antenne de YBa 2Cu3O7-delta, ce qui nous permet d'extraire les proprietes intrinseques de ce dernier. Pour confirmer la validite du modele

  8. Etude de l'influence de la temperature et de l'humidite sur les proprietes mecaniques en traction des fibres de chanvre et de coco

    NASA Astrophysics Data System (ADS)

    Ho Thi, Thu Nga

    L'objectif de cette etude fut d'etablir l'effet de l'humidite et de la temperature sur la resistance en traction et le module elastique des fibres de chanvre et de coco. Deux etudes ont ete realisees afin d'atteindre cet objectif. La premiere vise l'absorption de l'humidite dans ces fibres en exposition dans l'air (de 0%RH a 80%RH) ainsi que l'absorption de l'eau dans ces fibres immergees dans l'eau aux differentes temperatures. La deuxieme consiste a mesurer la resistance en traction et le module elastique de ces fibres sous differentes conditions d'humidite et de temperature. En basant sur les resultats experimentaux obtenus, les methodes semi empiriques et de reseaux de neurones ont ete utilisees pour but de predire les proprietes en traction (resistance et module d'elasticite) des fibres de chanvre et de coco sous l'influence de l'humidite et de la temperature.

  9. Reconstruction de la surface de Fermi dans l'etat normal d'un supraconducteur a haute Tc: Une etude du transport electrique en champ magnetique intense

    NASA Astrophysics Data System (ADS)

    Le Boeuf, David

    Des mesures de resistance longitudinale et de resistance de Hall en champ magnetique intense transverse (perpendiculaire aux plans CuO2) ont ete effectuees au sein de monocristaux de YBa2Cu3Oy (YBCO) demacles, ordonnes et de grande purete, afin d'etudier l'etat fondamental des supraconducteurs a haute Tc dans le regime sous-dope. Cette etude a ete realisee en fonction du dopage et de l'orientation du courant d'excitation J par rapport a l'axe orthorhombique b de la structure cristalline. Les mesures en champ magnetique intense revelent par suppression de la supraconductivite des oscillations magnetiques des resistances longitudinale et de Hall dans YBa2Cu 3O6.51 et YBa2Cu4O8. La conformite du comportement de ces oscillations quantiques au formalisme de Lifshitz-Kosevich, apporte la preuve de l'existence d'une surface de Fermi fermee a caractere quasi-2D, abritant des quasiparticules coherentes respectant la statistique de Fermi-Dirac, dans la phase pseudogap d'YBCO. La faible frequence des oscillations quantiques, combinee avec l'etude de la partie monotone de la resistance de Hall en fonction de la temperature indique que la surface de Fermi d'YBCO sous-dope comprend une petite poche de Fermi occupee par des porteurs de charge negative. Cette particularite de la surface de Fermi dans le regime sous-dope incompatible avec les calculs de structure de bande est en fort contraste avec la structure electronique presente dans le regime surdope. Cette observation implique ainsi l'existence d'un point critique quantique dans le diagramme de phase d'YBCO, au voisinage duquel la surface de Fermi doit subir une reconstruction induite par l'etablissement d'une brisure de la symetrie de translation du reseau cristallin sous-jacent. Enfin, l'etude en fonction du dopage de la resistance de Hall et de la resistance longitudinale en champ magnetique intense suggere qu'un ordre du type onde de densite (DW) est responsable de la reconstruction de la surface de Fermi. L'analogie de

  10. Chromosomal mapping of human genes by radioactive hybridization of cDNAs to Centre d'Etude du Polymorphisme humain high density gridded filter sets.

    PubMed

    Claas, A; Savelyeva, L; Pillmann, A; Schwab, M

    2000-08-01

    Chromosomal assignment of human transcribed sequences has been done mainly by high throughput genome analysis in specialized genome centres and, in a more classical fashion, by fluorescence in-site hybridization (FISH) analysis. Not every laboratory has the ability to map cDNAs by FISH analysis. We here report a rapid mapping approach that is based on the hybridization of cDNA probes to high density gridded Centre d'Etude du Polymorphisme Humain filters followed by subsequent computational analysis by database searches in the internet. Not only transcribed sequences but also genomic DNA could be subjected to this mapping approach. The presented approach allows to map human transcribed and genomic DNAs within 1-3 days and with a high level of resolution that will constantly increase in line with the incorporation of data deriving from high throughput genome mapping.

  11. Randomized control trial for the assessment of the anti-albuminuric effects of topiroxostat in hyperuricemic patients with diabetic nephropathy (the ETUDE study).

    PubMed

    Kato, Sawako; Ando, Masahiko; Mizukoshi, Toshihiro; Nagata, Takanobu; Katsuno, Takayuki; Kosugi, Tomoki; Tsuboi, Naotake; Maruyama, Shoichi

    2016-05-01

    Proteinuria is an established risk factor for diabetic nephropathy. Recent studies indicate that some xanthine oxidase inhibitors have a renoprotective effect. The aim of this study was to assess whether topiroxostat reduces albuminuria in hyperuricemic patients with diabetic nephropathy and overt proteinuria. The ETUDE study is an ongoing 24-week, multicenter, open-label, randomized (1:1), parallel group study involving hyperuricemic patients with diabetic nephropathy (estimated glomerular filtration rate [eGFR] ≥ 20 mL/min/1.73 m(2)) and overt proteinuria (0.3 ≤ urine protein to creatinine ratio (UPCR) < 3.5 g/g Cr). Patients are randomly assigned to high dose (topiroxostat 160 mg daily) or low dose (topiroxostat 40 mg daily) on top of standard of care. The primary endpoint is the change in albuminuria indicated by urine albumin-to-creatinine ratio after 24 treated weeks relative to the baseline values. This trial was registered at the Japanese University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR: UMIN 000015403). The background, rationale, and study design of this trial are presented here. Seventy-six patients from four registered facilities have already been enrolled and received at least one dose of topiroxostat. This trial will end in 2017. The ETUDE trial is the first randomized controlled study of topiroxostat in hyperuricemic patients with diabetic nephropathy and overt proteinuria. We will clarify the pleiotropic function of topiroxostat including an anti-albumiuric effect as well as its effects on safely decreasing serum uric acid levels.

  12. Etude d'un systeme de recuperation et de stockage de chaleur pour un systeme eolien-diesel avec stockage d'air comprime

    NASA Astrophysics Data System (ADS)

    Remillon, Thibaut

    La recherche presentee dans ce memoire porte sur les systemes hybrides eolien-diesel avec stockage d'air comprime (SHEDAC) adaptes a la production d'electricite en sites isoles, et plus precisement sur l'apport d'un systeme de recuperation et de stockage de chaleur (TES) au fonctionnement de ces systemes. Le principe de fonctionnement est le suivant. Quand la puissance eolienne est excedentaire par rapport aux besoins de la charge, le surplus d'energie est utilise pour comprimer de l'air. De ce processus resulte un rechauffement de l'air, on choisit d'extraire et de stocker la chaleur separement. Lors de la phase de restitution d'energie, l'air comprime utilise pour suralimenter le moteur thermique est rechauffe en utili sant la chaleur stockee precedemment. Tout au long de l'etude, nous avons seulement pris en compte la chaleur provenant du processus de compression de l'air, et neglige en tous points du systeme les echanges de chaleur avec le milieu exterieur. Pour quantifier l'apport du systeme de stockage de chaleur, nous avons tout d'abord mene une etude bibliographique sur ces systemes, pour identifier les meilleures solutions disponibles. Ensuite, on a modelise une de ces solutions sous Simulink pour etudier son fonctionnement de maniere plus precise. D'autre part, on a modelise un systeme de stockage de chaleur ideal pour quantifier l'apport maximal d'un TES sur les performances du SHEDAC. Nous avons conclu que les TES les plus adaptes aux systemes SHEDAC etaient les solutions actives directes a deux reservoirs, et que, pour beneficier au maximum du systeme de stockage de chaleur, il etait interessant de realiser la detente de l'air comprime stocke dans un moteur a air comprime, pour maximiser la recuperation d'energie mecanique.

  13. Etude numerique et experimentale de la reponse vibro-acoustique des structures raidies a des excitations aeriennes et solidiennes

    NASA Astrophysics Data System (ADS)

    Mejdi, Abderrazak

    compte. Les modeles developpes ont permis de conduire plusieurs etudes parametriques sur les proprietes vibro-acoustiques des structures d'avions facilitant ainsi la tache des concepteurs. Dans le cadre de cette these, un article a ete publie dans le Journal of Sound and Vibration et trois autres soumis, respectivement aux Journal of Acoustical Society of America, International Journal of Solid Mechanics et au Journal of Sound and Vibration Mots cles : structures raidies, composites, vibro-acoustique, perte par transmission.

  14. Etude de L'energie Moyenne de Creation de Paire dans les Detecteurs de Particules AU Silicium Amorphe Hydrogene

    NASA Astrophysics Data System (ADS)

    Dubeau, Jacques

    Ce travail porte sur la mesure et le calcul de l'energie de creation d'une paire electron-trou, epsilon_{p}, par une particule ionisante dans des detecteurs en couches minces au a-Si:H. Cette etude fut realisee a l'aide de dispositifs specialement concus et qui sont de deux types. Le premier emprunte au domaine des cellules photovoltaiques des structures p/i/n qui ont des couches dopees de ~30 nm mais dont on augmente l'epaisseur de la couche sensible, la couche i, a 3 ou 4 mum. Ces dispositifs peuvent etre polarises en inverse jusqu'a 20 V/ mum. Le second type consiste aussi en des structures p/i/n qui cette fois sont adaptees specialement aux applications de detection. Ces nouveaux dispositifs possedent une couche p de plus de 300 nm qui attenue l'injection d'electrons lors de l'application de la tension inverse, prevenant ainsi le claquage premature et permettant l'application de tensions de plus de 60 V/mum. De plus, ils ont une couche i faisant de 4 a 18 mu m. Nous avons soumis ces dispositifs a des protons et des particules alpha couvrant un domaine de dE/dx de 7.5 a 300 keV/mum. On met ainsi en evidence deux regimes d'operations. Premierement, lorsqu'on utilise des particules ayant des dE/dx eleves, a des incidences normales a la surface du detecteur et que la tension appliquee aux bornes du dispositif est faible, le signal est fortement attenue par des effets plasmas. Deuxiemement, a de fortes tensions pour des particules a incidences obliques et dE/dx faibles, l'amplitude du signal est proportionnelle a l'energie deposee dans la zone i du detecteur. Cependant, ce signal n'est pas sature et il semble augmenter avec la tension au-dela de la tension de claquage. De plus, on demontre qu'a des tensions intermediaires le signal est plus eleve si la tension est pulsee et si le temps d'integration de l'electronique est long (~ 20mus). En extrapolant l'amplitude du signal a une tension infinie nous obtenons une valeur de epsilon _{p} affranchie de tout effet de

  15. Etude exploratoire des conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial

    NASA Astrophysics Data System (ADS)

    Robitaille, Jean-Marc

    Il existe peu d'etudes sur les conceptions touchant les domaines de la biologie, notamment sur les conceptions de la circulation sanguine Nous avons observe egalement l'absence de recherche menee aupres d'eleves de l'ordre collegial sur cette question. Nous avons voulu combler une lacune en menant une recherche sur les conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial. Pour mener cette recherche nous nous sommes inspires d'une methode developpee par Treagust (1988). Le premier niveau de formulation didactique etablit l'architecture du systeme et la fonction nutritive de la circulation. Le second niveau de formulation didactique decrit et relie les parametres de la dynamique de la circulation et leur relation: Pression, Debit et Resistance. Le troisieme niveau de formulation didactique s'interesse au controle de la circulation du sang dans un contexte d'homeostasie qui implique la regulation de la pression arterielle. Nous avons construit un questionnaire en nous guidant sur les niveaux de formulation didactique et l'analyse des entrevues menees aupres de dix-huit eleves, representatifs de la population cible. Ce questionnaire fut administre a un echantillon de 2300 eleves disperses dans six colleges de la region de Montreal. Notre echantillon comprend des eleves inscrits a des programmes de l'ordre collegial en Sciences de la nature et en Techniques de la sante et qui n'ont pas suivi le cours sur la circulation sanguine. Notre analyse des reponses des eleves de notre echantillon aux questions sur le premier niveau de formulation didactique revele que la majorite des eleves considerent que le systeme circulatoire relie les organes les uns aux autres dans un circuit en serie. Notre analyse revele egalement que la majorite des eleves estiment que les nutriments sont extraits du sang par les organes selon un processus de selection base sur les besoins determines par la fonction de l'organe. Ces besoins sont differents selon les organes qui ne

  16. L'etude de l'InP et du GaP suite a l'implantation ionique de Mn et a un recuit thermique

    NASA Astrophysics Data System (ADS)

    Bucsa, Ioan Gigel

    Cette these est dediee a l'etude des materiaux InMnP et GaMnP fabriques par implantation ionique et recuit thermique. Plus precisement nous avons investigue la possibilite de former par implantation ionique des materiaux homogenes (alliages) de InMnP et GaMnP contenant de 1 a 5 % atomiques de Mn qui seraient en etat ferromagnetique, pour des possibles applications dans la spintronique. Dans un premier chapitre introductif nous donnons les motivations de cette recherche et faisons une revue de la litterature sur ce sujet. Le deuxieme chapitre decrit les principes de l'implantation ionique, qui est la technique utilisee pour la fabrication des echantillons. Les effets de l'energie, fluence et direction du faisceau ionique sur le profil d'implantation et la formation des dommages seront mis en evidence. Aussi dans ce chapitre nous allons trouver des informations sur les substrats utilises pour l'implantation. Les techniques experimentales utilisees pour la caracterisation structurale, chimique et magnetique des echantillons, ainsi que leurs limitations sont presentees dans le troisieme chapitre. Quelques principes theoriques du magnetisme necessaires pour la comprehension des mesures magnetiques se retrouvent dans le chapitre 4. Le cinquieme chapitre est dedie a l'etude de la morphologie et des proprietes magnetiques des substrats utilises pour implantation et le sixieme chapitre, a l'etude des echantillons implantes au Mn sans avoir subi un recuit thermique. Notamment nous allons voir dans ce chapitre que l'implantation de Mn a plus que 1016 ions/cm 2 amorphise la partie implantee du materiau et le Mn implante se dispose en profondeur sur un profil gaussien. De point de vue magnetique les atomes implantes se trouvent dans un etat paramagnetique entre 5 et 300 K ayant le spin 5/2. Dans le chapitre 7 nous presentons les proprietes des echantillons recuits a basses temperatures. Nous allons voir que dans ces echantillons la couche implantee est polycristalline et les

  17. Etude Par Spectroscopie Infrarouge des Oxydes Moleculaires Superoxyde de Potassium, Peroxyde de Potassium et Trioxyde de Silicium Isoles EN Matrice D'argon

    NASA Astrophysics Data System (ADS)

    Tremblay, Benoit

    1995-01-01

    A l'aide de la spectroscopie d'absorption infrarouge et de la technique d'isolation en matrice d'argon, nous avons repris l'etude des differents oxydes moleculaires qui se forment lorsque l'oxygene moleculaire se trouve dans des agregats avec du potassium, du silicium et de l'oxyde de silicium SiO. Le choix des oxydes moleculaires KO_2 et K_2O_2 a ete motive par le fait qu'ils ont souvent ete mis en evidence dans tres travaux en physique des surfaces lors de letude du systeme O_2/K/Si. Ces oxydes avaient deja ete identifies par spectroscopie infrarouge en matrice d'argon au debut des annees soixante-dix. Pour KO_2, l'observation des modes nu_2 et nu_3 pour de nombreuses especes isotopiques nous a permis de deduire la longueur de la liaison K-O et de l'angle O-K-O. En effet, la construction d'un champ de force harmonique nous a permis de determiner sa structure et des constantes de force qui reprodusient tres bien les frequences experimentales observees. L'etude de l'oxyde K_2O _2 s'est averee interessante car avant notre travail, seule une vibration avait ete mise en evidence. Nous avons reussi a observer deux nouvelles vibrations fondamentales: une bande infrarouge faible a 185 cm^{-1}, avec les isotopes ^{16}O _2, ^{18}O _2 et ^{16} O^{18}O de l'oxygene, et une autre, activee en infrarouge avec l'isotope ^{16}O^{18 }O a 405 cm^{-1}. Les donnees experimentales etant insuffisantes pour deduire la structure de la molecule, des calculs theoriques avec la methode de la fonctionnelle de la densite ont donne le structure et les vibrations non observees du K _2O_2. Ces donnees supplementaires sont venues completer les resultats experimentaux et nous ont permis de construire un champ de force harmonique avec <=uel nous avons trouve des constantes de force qui reproduisent tres bien les frequences observees. Les calculs theoriques ont monte que K_2O _2 doit etre de structure C_ {rm 2v}, bien que la structure D _{rm 2h} ne puisse pas etre rejetee, puisque qu'il y a un

  18. Etude des phenomenes de penetration des especes chimiques dans les revetements cathodiques des cuves d'electrolyse de l'aluminium

    NASA Astrophysics Data System (ADS)

    Brisson, Pierre-Yves

    Cette these decrit l'etude effectuee sur les phenomenes d'insertion du sodium et de penetration du bain electrolytique dans les revetements cathodiques des cuves d'electrolyse de l'aluminium. L'etude fut effectuee a l'aide d'un montage permettant d'effectuer l'electrolyse en laboratoire. Trois types de revetement cathodiques furent etudies : des blocs semi-graphitique, des blocs graphitiques et des blocs graphitises. L'insertion du sodium dans les trois differents types de blocs fut etudiee a l'aide de la spectrometrie des photoelectrons X (XPS). L'analyse a permis de mettre en evidence deux formes de sodium dans l'anthracite et la phase liante des materiaux semi-graphitiques et graphitiques, indiquant qu'une fraction du sodium se retrouve sous forme adsorbee dans les micropores des materiaux alors que l'autre fraction est inseree dans la structure cristalline du carbone. Dans les phases graphitiques (materiaux graphitises et graphitiques), seuls les micropores sont occupes par le sodium Ce resultat explique la tendance observee selon laquelle l'ajout de graphite dans les blocs permet d'abaisser le gonflement sodique. Les mecanismes de penetration du bain dans le reseau poreux des materiaux furent etudies en microscopie electronique et en diffraction des rayons X sur des echantillons apres differents temps d'electrolyses et en variant l'atmosphere (soit sous argon ou sous azote). Ces analyses ont permis d'identifier le mecanisme conduisant a la mouillabilite du bain sur le carbone en fonction de l'atmosphere entourant l'electrolyse. Ainsi, sous azote, la formation de NaCN dans les pores des materiaux par reactions entre le sodium et l'azote permet une mouillabilite accrue du bain alors qu'en absence d'azote (sous argon), le carbure d'aluminium, formes a la surface des pores, joue un role similaire. Dans ce dernier cas, la penetration du bain est moins rapide etant donnee la necessite de toujours amener des especes contenant de l'aluminium en tete du front de

  19. Etude experimentale des excitations topologiques de l'effet Hall quantique a nu = 1 dans les heterostructures semiconductrices a double puits quantique

    NASA Astrophysics Data System (ADS)

    Charlebois, Serge

    De nombreux travaux theoriques et experimentaux ont ete publies sur les excitations topologiques de gaz electroniques bidimensionnels (GE2D), appellees skyrmions, dans le regime de l'effet Hall quantique a remplissage unitaire. On attend des excitations semblables appellees bimerons dans les systemes formes de deux GE2D couples. Contrairement au cas des GE2D simples, aucune experience n'a, a notre connaissance, presente la mesure d'une propriete specifique aux bimerons. Nous presentons dans cette these des travaux experimentaux ayant pour objectif l'etude d'excitations topologiques dans les heterostructures a double puits quantique. Une manifestation attendue (les bimerons est la presence d'une anisotropie dans la conductivite a travers une constriction. Nous avons concu un dispositif original a point de contact a trois grilles non-coplanaires. Ce dispositif a trois grilles a la particularite de permettre la creation d'une constriction etroite dans le double GE2D tout en permettant l'equilibrage de la densite electronique entre les deux puits dans l'etroit canal de conduction. Nous avons fabrique ce dispositif de taille submicronique par electrolithographie sur des heterostructures a double puits. Les dispositifs ainsi fabriques ont ete etudies a basse temperature (0.3K) et ont montre un fonctionnement conforme aux attentes. Les travaux n'ont pas permis de mettre en evidence une anisotropie de transport revelatrice de l'existence de bimerons. Cette these est a notre connaissance la premiere etude experimentale visant la realisation de l'experience d'anisotropie de transport et est ainsi une contribution significative a l'avancement des connaissances dans ce domaine. Les travaux theoriques que nous presentons ont permis de montrer l'effet des excitations topologiques sur la capacite grille-GE2D du systeme. Ces travaux ouvrent la voie de la detection des bimerons par l'intermediaire de la mesure de la capacite grille-GE2D ou encore de la susceptibilite electrique du

  20. Physical activity patterns in the French 18-74-year-old population: French Nutrition and Health Survey (Etude Nationale Nutrition Santé, ENNS) 2006-2007.

    PubMed

    Salanave, Benoit; Vernay, Michel; Szego, Emmanuelle; Malon, Aurélie; Deschamps, Valérie; Hercberg, Serge; Castetbon, Katia

    2012-11-01

    To describe detailed physical activity and sedentary behaviour in French adults across physical activity categories. The French Nutrition and Health Survey (Etude Nationale Nutrition Santé, ENNS), conducted in 2006-2007, was a national cross-sectional survey based on three-stage random sampling. The International Physical Activity Questionnaire (IPAQ) was used to classify participants into three physical activity categories. Time spent in a sitting position and time spent in front of a screen were used as markers of sedentary behaviour. France. Adults (n 2971) aged 18 to 74 years were included. Overall, 29·5 % of men and 23·6 % of women were classified into the high-IPAQ category, while 36·1 % of men and 37·5 % of women were in the low-IPAQ category. For each intensity level of physical activity (vigorous intensity, moderate intensity or walking), the number of active days per week decreased from the high- to the low-IPAQ category and daily duration of physical activity was longer in the high-IPAQ category than in the other two categories; 6 % of adults declared neither vigorous nor moderate nor walking activities. For most adults in the low-IPAQ category, an increasing number of active days per week would be sufficient to attain the moderate-IPAQ category. This should be taken into account in public health initiatives aimed at promoting physical activity.

  1. A microcosm of musical expression. I. Quantitative analysis of pianists' timing in the initial measures of Chopin's Etude in E major.

    PubMed

    Repp, B H

    1998-08-01

    Patterns of expressive timing were measured in bars 1-5 of 115 commercially recorded performances of Chopin's Etude in E major, op. 10, No. 3. These patterns were subjected to principal components analysis, which suggested at least four independent "timing strategies": (1) major ritards at the ends of melodic gestures; (2) acceleration within some of these gestures, without final ritards; (3) extreme lengthening of the initial downbeat; and (4) ritards between as well as within melodic gestures. Strategies 1 and 4 respond in different ways to the melodic-rhythmic grouping structure of the music, and strategy 3 merely represents a local emphasis. Strategy 2 is the one most difficult to rationalize; it does not seem to represent an alternative structural interpretation of the music but rather an alternative gestural shaping. Each individual pianist's timing pattern could be described as a weighted combination of these four strategies plus idiosyncratic variation. A wide variety of combinations was represented, and no two individual patterns were exactly the same. In addition, there was a wide range of basic tempi and of degrees of tempo modulation. There were no strong relationships between any of these variables and sociocultural characteristics of the artists, although some weak trends were observed.

  2. Etudes optiques de nouveaux materiaux laser: Des orthosilicates dopes a l'ytterbium: Le yttrium (lutetium,scandium) pentoxide de silicium

    NASA Astrophysics Data System (ADS)

    Denoyer, Aurelie

    La decouverte et l'elaboration de nouveaux materiaux laser solides suscitent beaucoup d'interet parmi la communaute scientifique. En particulier les lasers dans la gamme de frequence du micron debouchent sur beaucoup d'applications, en telecommunication, en medecine, dans le domaine militaire, pour la, decoupe des metaux (lasers de puissance), en optique non lineaire (doublage de frequence, bistabilite optique). Le plus couramment utilise actuellement est le Nd:YAG dans cette famille de laser, mais des remplacants plus performants sont toujours recherches. Les lasers a base d'Yb3+ possedent beaucoup d'avantages compares aux lasers Nd3+ du fait de leur structure electronique simple et de leur deterioration moins rapide. Parmi les matrices cristallines pouvant accueillir l'ytterbium, les orthosilicates Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5 se positionnent tres bien, du fait de leur bonne conductivite thermique et du fort eclatement de leur champ cristallin necessaire a l'elaboration de lasers quasi-3 niveaux. De plus l'etude fine et systematique des proprietes microscopiques de nouveaux materiaux s'avere toujours tres interessante du point de vue de la recherche fondamentale, c'est ainsi que de nouveaux modeles sont concus (par exemple pour le champ cristallin) ou que de nouvelles proprietes inhabituelles sont decouvertes, menant a de nouvelles applications. Ainsi d'autres materiaux dopes a l'ytterbium sont connus pour leurs proprietes de couplage electron-phonon, de couplage magnetique, d'emission cooperative ou encore de bistabilite optique, mais ces proprietes n'ont encore jamais ete mises en evidence dans Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5. Ainsi, cette these a pour but l'etude des proprietes optiques et des interactions microscopiques dans Yb:Y2SiO 5, Yb:Lu2SiO5 et Yb:Sc2SiO5. Nous utilisons principalement les techniques d'absorption IR et de spectroscopie Raman pour determiner les excitations du champ cristallin et les modes de vibration dans le materiau

  3. Etudes on 1/N

    NASA Astrophysics Data System (ADS)

    Starinets, Andrei Olegovich

    A number of problems in string theory and lattice statistical mechanics is studied using the large N approximation, with N being the dimension of the fundamental representation of the underlying symmetry algebra. As the first problem, the absorption of a minimally coupled massless scalar in the gravitational background created by a stack of near-extremal black three-branes is considered. The low-temperature asymptotic expansion and the high-temperature perturbative expansion are obtained. A field-theoretical calculation of the absorption cross section in the brane's world-volume theory is also performed. As an application, the shear viscosity of a strongly coupled Yang-Mills plasma is computed. In the second problem, we study supergravity solutions with two asymptotically Anti de Sitter regions which are conjectured to describe the renormalization group flow of a four-dimensional field theory from a UV fixed point to an interacting IR fixed point. We show that, in the UV (IR) limit, the two-point function of a minimally-coupled scalar field depends only on the UV (IR) region of the metric, asymptotic to AdS5 thus lending a support to the conjecture. In the third problem, monotonicity and other properties of the canonical c-function in some holographic duals of 4-d quantum field theories are investigated. The canonical c-function and its derivatives are related to the 5-d Green's function of the dual supergravity theory. In the fourth problem, we study solutions of the equations (Δ - λ)φ = 0 and (Δ - λ)2φ = 0 on the covering space C AdSd of the d-dimensional Anti de-Sitter space subject to various boundary conditions, and we analyze their connection to the unitary irreducible representations of SO (d - 1, 2). Finally, as the fifth problem, we compute the phase diagram in the N --> ∞ limit for lattice RPN-1, CPN-1 and QPN-1 σ- models with the quartic action, and more generally for mixed isovector/isotensor models. We show that the N = ∞ limit exhibits phase transitions that are forbidden for any finite N. We clarify the origin of these pathologies by examining the exact solution of the one- dimensional model. We conjecture the correct phase diagram for finite N as a function of the spatial dimension d. We also obtain new results concerning the complex zeros of confluent hypergeometric functions.

  4. Synthese, etude structurale et electrochimique des materiaux d'electrode positive d'oxydes mixtes lithium cobalt nickel oxide (0 /= 1) pour les batteries rechargeables au lithium

    NASA Astrophysics Data System (ADS)

    Grincourt, Yves

    Depuis une dizaine d'annees, on observe un interet grandissant pour les batteries rechargeables au lithium de tension superieure a 4 volts. La commercialisation de ces batteries pour l'electronique grand marche tend de plus en plus a supplanter celle des accumulateurs Ni-Cd et Ni-MH, de tension nominate 1,2 V. Ces batteries au lithium font appel a des materiaux d'electrode positive (cathode a la decharge) du type oxydes mixtes de metaux de transition LiMnO 2, LiMn2O4, LiNiO2 ou LiCoO2. Si le compose LiCoO2 est relativement aise a synthetiser, il n'en demeure pas moins que le cobalt reste un metal plus couteux compare au nickel et au manganese. La synthese de LiNiO2, quart a elle, demeure un probleme du point de vue stoechiometrique. Un defaut de lithium (5 a 10% molaire) conduira a des proprietes electrochimiques mediocres de la batterie. Dans cette etude nous nous proposons donc de preparer par voie humide et par voie seche les materiaux d'electrode positive de la famille LiCoyNi1-yO2 aver (0 ≤ y ≤ 1) et d'etudier en detail l'influence du pourcentage de nickel et de cobalt sur les proprietes electrochimiques des oxydes mixtes Li-Ni-Co. Une des caracteristiques est la morphologie plus fine des poudres de materiaux, observes par microscopie electronique a balayage (MEB). Un traitement thermique a plus basse temperature (750°C) que pour LiCoO2 (850°C) ainsi qu'un leger exces de lithium dans la preparation, ont permis d'aboutir a un materiau de stoechiometrie quasi parfaite. Neanmoins, le role de pilfer joue par 2 a 4% de moles de Ni2+ presents sur les sites lithium, permet de conserver intacte la structure hexagonale de la maille entre deux cycles consecutifs. Afin de mieux comprendre l'influence du vieillissement dune demi-pile Li/LiMeO2 (Me = Ni, Co) a temperature ambiante, des etudes electrochimiques et d'impedance spectroscopique ont ete menees en parallele. Le vieillissement de la cellule s'accompagne seulement dune chute de son potentiel due a son auto

  5. Mise au point du rheometre a cisaillement annulaire pour l'etude de rheologie d'un mastic bitumineux avec verre incorpore =

    NASA Astrophysics Data System (ADS)

    El Mansouri, Souleimane

    Dans le domaine viscoelastique lineaire (VEL, domaine des petites deformations), le comportement thermomecanique du bitume et du mastic bitumineux (melange uniforme de bitume et de fillers) a ete caracterise au Laboratoire des Chaussees et Materiaux Bitumineux (LCMB) de l'Ecole de technologie superieure (ETS) avec l'appui de nos partenaires externes : la Societe des Alcools du Quebec (SAQ) et Eco Entreprises Quebec (EEQ). Les proprietes rheologiques des bitumes et des mastics ont ete mesurees grâce a un nouvel outil d'investigation appele, Rheometre a Cisaillement Annulaire (RCA), sous differentes conditions de chargement. Cet appareil permet non seulement de solliciter des eprouvettes de tailles importantes par rapport a celles utilisees lors des essais classiques, mais aussi d'effectuer des essais en conditions quasi-homogenes, ce qui permet de donner acces a la loi de comportement des materiaux. Les essais sont realises sur une large gamme de temperatures et de frequences (de -15 °C a 45°C et de 0,03Hz a 10 Hz). Cette etude a ete menee principalement pour comparer le comportement d'un bitume avec celui d'un mastic bitumineux dans le domaine des petites deformations. neanmoins, dans une seconde perspective, on s'interesse a l'influence des fillers de verre de post-consommation sur le comportement d'un mastic a faibles niveaux de deformations en comparant l'evolution des modules complexes de cisaillements (G*) d'un mastic avec fillers de verre et un mastic avec fillers conventionnels (calcaire). Enfin, le modele analogique 2S2P1D est utilise pour simuler le comportement viscoelastique lineaire des bitumes et des mastics bitumineux testes lors de la campagne experimentale.

  6. Le transfert de connaissances entre les mathematiques et les sciences. Une etude exploratoire aupres d'eleves de 4e secondaire

    NASA Astrophysics Data System (ADS)

    Samson, Ghislain

    2003-06-01

    Au moment ou dans plusieurs pays on travaille a refondre les programmes d'etudes, tant au primaire qu'au secondaire, l'interet pour le transfert renait. Un des concepts fondamentaux en apprentissage consiste en l'habilete a reutiliser de facon consciente et efficace un acquis d'une situation a une autre situation. Cette recherche emane de preoccupations professionnelles au moment ou le chercheur etait enseignant au secondaire. Au cours de ces annees, il lui a ete possible de constater que plusieurs eleves percevaient difficilement les liens presents entre les disciplines mathematiques et scientifiques. Des travaux en psychologie cognitive et plus particulierement selon une perspective du traitement de l'information ont servi de cadre de reference pour evaluer et analyser les capacites de transfert aupres d'eleves de 4e secondaire. Ce cadre de reference permet de formuler le principal objectif qui est de mieux comprendre le processus de transfert chez des eleves en situation de resolution de problemes scientifiques. Cette these s'interesse donc au transfert en tant que phenomene important du processus d'apprentissage au sens de l'integration. La methode de recherche choisie, de nature qualitative, est principalement axee sur l'evaluation de la capacite a transferer des connaissances lors d'une epreuve et d'un entretien. Pour evaluer ce potentiel de transfert, nous avons elabore deux outils: une epreuve en mathematiques et en sciences et un guide d'entretien. Pour la passation de l'epreuve, le chercheur a pu compter sur la collaboration de 130 sujets provenant de deux ecoles. L'entretien complete la prise de donnees avec 13 sujets ayant accepte de poursuivre l'etude. Les donnees recueillies par ces instruments font ensuite l'objet d'une analyse de contenu. En premier lieu, les verbatims de l'epreuve et de l'entretien ont ete transcrits, puis codifies. La correction des reponses fournies pour les problemes resolus s'est faite a partir d'une grille d

  7. Gestion des ressources hydriques adaptee aux changements climatiques pour la production optimale d'hydroelectricite. Etude de cas: Bassin versant de la riviere Manicouagan

    NASA Astrophysics Data System (ADS)

    Haguma, Didier

    Il est dorenavant etabli que les changements climatiques auront des repercussions sur les ressources en eau. La situation est preoccupante pour le secteur de production d'energie hydroelectrique, car l'eau constitue le moteur pour generer cette forme d'energie. Il sera important d'adapter les regles de gestion et/ou les installations des systemes hydriques, afin de minimiser les impacts negatifs et/ou pour capitaliser sur les retombees positives que les changements climatiques pourront apporter. Les travaux de la presente recherche s'interessent au developpement d'une methode de gestion des systemes hydriques qui tient compte des projections climatiques pour mieux anticiper les impacts de l'evolution du climat sur la production d'hydroelectricite et d'etablir des strategies d'adaptation aux changements climatiques. Le domaine d'etude est le bassin versant de la riviere Manicouagan situe dans la partie centrale du Quebec. Une nouvelle approche d'optimisation des ressources hydriques dans le contexte des changements climatiques est proposee. L'approche traite le probleme de la saisonnalite et de la non-stationnarite du climat d'une maniere explicite pour representer l'incertitude rattachee a un ensemble des projections climatiques. Cette approche permet d'integrer les projections climatiques dans le probleme d'optimisation des ressources en eau pour une gestion a long terme des systemes hydriques et de developper des strategies d'adaptation de ces systemes aux changements climatiques. Les resultats montrent que les impacts des changements climatiques sur le regime hydrologique du bassin de la riviere Manicouagan seraient le devancement et l'attenuation de la crue printaniere et l'augmentation du volume annuel d'apports. L'adaptation des regles de gestion du systeme hydrique engendrerait une hausse de la production hydroelectrique. Neanmoins, une perte de la performance des installations existantes du systeme hydrique serait observee a cause de l'augmentation des

  8. Contribution a l'etude de la binarite des etoiles de type Am. I. HD 125273, binaire spectroscopique a raies doubles

    NASA Astrophysics Data System (ADS)

    Ginestet, N.; Carquillat, J.-M.

    1998-06-01

    We present an observing program undertaken at Observatoire de Haute-Provence, for the search and study of spectroscopic binaries among Am stars. HD 125273 was recognized as an Am star some time ago \\cite[(Olsen 1980;]{ols80} \\cite[Abt 1984);]{abt84} observations, carried out with the CORAVEL spectrovelocimeter, show that this star is a double-lined spectroscopic binary; its orbital elements are as follows: P = 7.482664 days; T = 2448665.660 JD; omega_1 = 355.3() deg; e = 0.071; K_1 = 49.82 km/s; K_2 = 51.75 km/s; V_0 = -17.42 km/s; a_1 sini = 5.113 Gm; a_2 sini = 5.311 Gm; M_1 sin(3i) = 0.412 M_sun;; M_2 sin(3i) = 0.396 M_sun. Stroemgren photometry of the star \\cite[(Olsen 1983)]{ols83} permits us to estimate the following mean physical parameters for the components of the binary: T_eff = 7500 K; log g = 3.70; M_v = 1.24; M = 2.1 M_sun;; R = 3.2 R_sun, and to specify the evolutionary status of the system. Assuming the above mass for the components, we found i ~ 35() deg and a ~ 26 R_sun. This system is thus a detached one without possibility of eclipses. It is likely that the two components are Am stars of very close characteristics. The v sini values, determined from the correlation dips given by CORAVEL, are near 11 km/s for both components. We retain for this binary the hypothesis of rotation-revolution synchronism, because it leads to a value of the radius of the stars in agreement both with the above value and the results of a previous study by \\cite[Kitamura & Kondo (1978)]{kit78} of similar, but eclipsing, systems. The ratio of the correlation dip areas indicates a magnitude difference Delta m_v ~ 0.2 mag. As expected in detached systems of main sequence stars, such as Am's, HD 125273 obeys the mass-luminosity law. Etude effectuee a partir d'observations faites a l'Observatoire de Haute-Provence.

  9. Etude de la performance des radars hautes-frequences CODAR et WERA pour la mesure des courants marins en presence partielle de glace de mer

    NASA Astrophysics Data System (ADS)

    Kamli, Emna

    Les radars hautes-frequences (RHF) mesurent les courants marins de surface avec une portee pouvant atteindre 200 kilometres et une resolution de l'ordre du kilometre. Cette etude a pour but de caracteriser la performance des RHF, en terme de couverture spatiale, pour la mesure des courants de surface en presence partielle de glace de mer. Pour ce faire, les mesures des courants de deux radars de type CODAR sur la rive sud de l'estuaire maritime du Saint-Laurent, et d'un radar de type WERA sur la rive nord, prises pendant l'hiver 2013, ont ete utilisees. Dans un premier temps, l'aire moyenne journaliere de la zone ou les courants sont mesures par chaque radar a ete comparee a l'energie des vagues de Bragg calculee a partir des donnees brutes d'acceleration fournies par une bouee mouillee dans la zone couverte par les radars. La couverture des CODARs est dependante de la densite d'energie de Bragg, alors que la couverture du WERA y est pratiquement insensible. Un modele de fetch appele GENER a ete force par la vitesse du vent predite par le modele GEM d'Environnement Canada pour estimer la hauteur significative ainsi que la periode modale des vagues. A partir de ces parametres, la densite d'energie des vagues de Bragg a ete evaluee pendant l'hiver a l'aide du spectre theorique de Bretschneider. Ces resultats permettent d'etablir la couverture normale de chaque radar en absence de glace de mer. La concentration de glace de mer, predite par le systeme canadien operationnel de prevision glace-ocean, a ete moyennee sur les differents fetchs du vent selon la direction moyenne journaliere des vagues predites par GENER. Dans un deuxieme temps, la relation entre le ratio des couvertures journalieres obtenues pendant l'hiver 2013 et des couvertures normales de chaque radar d'une part, et la concentration moyenne journaliere de glace de mer d'autre part, a ete etablie. Le ratio des couvertures decroit avec l'augmentation de la concentration de glace de mer pour les deux types

  10. Comparison of Dietary Intakes Between a Large Online Cohort Study (Etude NutriNet-Santé) and a Nationally Representative Cross-Sectional Study (Etude Nationale Nutrition Santé) in France: Addressing the Issue of Generalizability in E-Epidemiology.

    PubMed

    Andreeva, Valentina A; Deschamps, Valérie; Salanave, Benoît; Castetbon, Katia; Verdot, Charlotte; Kesse-Guyot, Emmanuelle; Hercberg, Serge

    2016-11-01

    Despite some advantages over traditional methods, Web-based studies elicit concerns about generalizability. To address this issue, we compared dietary intakes between an electronic (e-) cohort study and a nationally representative survey. We studied 49,443 French volunteers aged 18-74 years recruited during 2009-2010 in the NutriNet-Santé Study, a general population-based e-cohort study. The Etude Nationale Nutrition Santé (ENNS; 2006-2007), a cross-sectional study with a nationally representative sample of 2,754 French adults aged 18-74 years, served as the reference data set. Reported dietary intakes from three 24-hour dietary records were weighted and compared between the two studies via Student t tests for mean location, using a >5% cutoff for establishing practically meaningful differences. We observed similar intakes as regards carbohydrates, total lipids, protein, and total energy. However, intakes of fruit and vegetables, fiber, vitamins B6, B9, C, D, and E, iron, and magnesium were higher in the e-cohort than in the ENNS, while intakes of alcohol and nonalcoholic beverages were lower in the e-cohort. Significant sex-specific differences were observed regarding vitamins A and B12, zinc, and potassium. True intake differences, mode effects, and volunteer bias might each contribute to explaining the findings. In the future, repeated use of the same tool in large e-cohorts with heterogeneous dietary exposures could serve research purposes and supplement group-level monitoring of dietary trends. The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Etude du processus de changement vecu par des familles ayant decide d'adopter volontairement des comportements d'attenuation des changements climatiques

    NASA Astrophysics Data System (ADS)

    Leger, Michel T.

    recension des ecrits sur le changement de comportement en environnement. Nous explorons egalement la famille comme systeme fonctionnel de sorte a mieux comprendre ce contexte d'action environnementale qui est, a notre connaissance, peu etudie. Dans le deuxieme article, nous presentons nos resultats de recherche concernant les facteurs d'influence observes ainsi que les competences manifestees au cours du processus d'adoption de nouveaux comportements environnementaux dans trois familles. Enfin, le troisieme article presente les resultats du cas d'une quatrieme famille ou les membres vivent depuis longtemps des modes de vie ecologique. Dans le cadre d'une demarche d'analyse par theorisation ancree, l'etude de ce cas modele nous a permis d'approfondir les categories conceptuelles identifiees dans le deuxieme article de sorte a produire une modelisation de l'integration de comportements environnementaux dans le contexte de la famille. Les conclusions degagees grace a la recension des ecrits nous ont permis d'identifier les elements qui pourraient influencer l'adoption de comportements environnementaux dans des familles. La recension a aussi permis une meilleure comprehension des divers facteurs qui peuvent affecter l'adoption de comportements environnementaux et, enfin, elle a permis de mieux cerner le phenomene de changement de comportement dans le contexte de la famille consideree comme un systeme. En appliquant un processus d'analyse inductif, a partir de nos donnees qualitatives, les resultats de notre etude multi-cas nous ont indique que deux construits conceptuels semblent influencer l'adoption de comportements environnementaux en famille : 1) les valeurs biospheriques communes au sein de la famille et 2) les competences collectivement mises a profit collectivement durant l'essai de nouveaux comportements environnementaux. Notre modelisation du processus de changement dans des familles indique aussi qu'une dynamique familiale collaborative et la presence d'un groupe de

  12. Etude de lasers a fibre emettant a 480 nm et du phenomene de coloration dans la fibre de ZBLAN dopee au thulium

    NASA Astrophysics Data System (ADS)

    Laperle, Pierre

    Cet ouvrage porte sur l'etude experimentale et theorique du laser a fibre de ZBLAN dopee au thulium pompe a 1112 nm par un laser Nd:YAG et emettant a 480 nm, ainsi que du phenomene de coloration causant la photodegradation du laser a fibre. Le rendement du laser a fibre depend de l'efficacite de la conversion de photons infrarouges en photons visibles par un mecanisme d'excitation en palier des ions trivalent thulium (Tm3+). Toutefois, cette efficacite est reduite par les transferts d'energie entre les ions Tm3+. De plus, le gain net est limite par l'absorption induite a la longueur d'onde laser pendant le pompage de la fibre a 1112 nm. Cette absorption induite s'avere etre le probleme le plus important a surmonter pour le developpement d'un laser a fibre a 480 nm qui soit stable et de haute puissance. La spectroscopie de l'ion Tm3+ dans la fibre de ZBLAN a ete realisee afin de determiner experimentalement les parametres essentiels a la modelisation theorique du laser a fibre. Les sections efficaces d'absorption et d'emission de l'ion Tm3+ ont ete calculees a partir des equations de Fuchtbauer-Ladenburg et des spectres d'intensite d'absorption et d'emission spontanee mesures experimentalement par excitation selective. Cette methode d'excitation a permis de resoudre spectralement certaines des transitions d'absorption mal connues dues a la difficulte de mesurer celles-ci de facon directe. L'identification des transferts d'energie (relaxation croisee et excitation cooperative en palier) dominants entre ions Tm 3+ a ete faite en comparant la probabilite d'interaction dipole-dipole electriques entre une paire d'ion Tm 3+. Les taux de transferts d'energie, quant a eux, ont ete mesures par excitation selective et la mesure du temps de vie des niveaux d'energie de l'ion Tm3+. La sensibilite de la fibre de ZBLAN a la lumiere et a la chaleur est decrite habituellement par leurs effets sur la transparence de la fibre, par exemple, photonoircissement, photoblanchiment et

  13. Le changement comme tradition dans la recherche et la formation a la recherche en biotechnologie et en peripherie Etude de cas en sciences de la sante, sciences naturelles et genie

    NASA Astrophysics Data System (ADS)

    Bourque, Claude Julie

    Le champ de la recherche scientifique et de la formation a la recherche est traverse depuis quelques dizaines d'annees par plusieurs courants et discours associes au changement, mais peu de travaux empiriques permettent de comprendre ce qui change concretement. C'est la contribution originale de cette these au champ de l'education, plus specifiquement a l'etude sociologique de l'enseignement superieur ou sont concentrees les activites liees a la triade thematique du programme doctoral dans lequel elle a ete produite : recherche, formation et pratique. L'enquete-terrain a ete realisee en 2009 et 2010 aupres de 808 repondants affilies a 60 etablissements au Quebec et a produit un vaste materiau de nature mixte (donnees quantitatives et qualitatives). Un portrait de la nebuleuse biotechnologique qui touche les secteurs des sciences de la sante, des sciences naturelles et du genie a ete realise. Ce domaine concerne des dizaines de disciplines et se revele de nature transdisciplinaire, mais les pratiques n'y sont pas davantage marquees par le changement que celles d'autres domaines connexes. Les dynamiques sociales ont fait l'objet d'analyses comparatives dans quatre contextes: le choix des programmes, des objets et des methodes, le financement, la diffusion et la planification de la carriere. Les resultats indiquent que les echanges entre les agents traditionnellement situes au coeur des activites de recherche dominent ces dynamiques dans tous les contextes etudies. L'etude des representations au fondement des pratiques a revele l'existence de trois ecoles de pensee qui coexistent dans le champ scientifique: academique, pragmatique et economiste. Ces ecoles permettent de categoriser les agents en fonction des zones de fractures qui marquent leurs oppositions tout en identifiant ce qu'ils ont en commun. Les representations et les pratiques liees a la formation temoignent d'un habitus plutot homogene, alors que les contradictions semblent plus souvent ancrees dans des

  14. Physical and genetic map of 5q31: use of fluorescence in situ hybridization data to identify errors in the CEPH database. Centre d'Etude de Polymorphisme Humain.

    PubMed

    Westbrook, C A; Le Beau, M M; Neuman, W L; Keinanen, M; Yamaoka, L H; Speer, M C; Espinosa, R; Nakamura, Y; Williamson, R; Mullan, M

    1994-01-01

    Chromosome 5, band q31, contains the genes responsible for a number of interesting genetic and malignant diseases, as well as many cloned genes. To prepare a high-resolution map of this region, eight anonymous DNA markers were mapped by combining genetic data derived from linkage analysis, with physical data obtained using two-color fluorescent in situ hybridization (FISH). Probe order was determined by FISH on metaphase cells, supplemented with interphase analysis, while genetic distance and likely order were determined by multipoint linkage analysis using genotype data from Centre d'Etude de Polymorphisme Humain (CEPH) pedigrees. Discrepancies between the genetic and physical maps suggested that there was a high rate of genotyping errors in the CEPH data for these markers, and prompted a statistical analysis to identify these errors. By assuming a known physical order (as determined by FISH) it was possible to identify markers which had the greatest degree of error. The average typing error was estimated at 1.8%, but several markers had much higher error rates; a 14% error rate was predicted for one locus, which was subsequently confirmed by retyping. The analysis led to the preparation of a revised map spanning 24.5 cM of 5q31. This study illustrates the power of FISH to determine physical order over a wide genomic distance, and demonstrates how order can be used as an adjunct to linkage analysis, particularly in the identification of genotyping errors.

  15. Optical properties of urban aerosol from airborne and ground-based in situ measurements performed during the Etude et Simulation de la Qualité de l'air en Ile de France (ESQUIF) program

    NASA Astrophysics Data System (ADS)

    Chazette, Patrick; Randriamiarisoa, Hariliva; Sanak, Joseph; Couvert, Pierre; Flamant, Cyrille

    2005-01-01

    Urban aerosol microphysical and optical properties were investigated over the Paris area coupling, for the first time, with dedicated airborne in situ instruments (nephelometer and particle sizers) and active remote sensor (lidar) as well as ground-based in situ instrumentation. The experiment, covering two representative pollution events, was conducted in the framework of the Etude et Simulation de la Qualité de l'air en Ile de France (ESQUIF) program. Pollution plumes were observed under local northerly and southerly synoptic wind conditions on 19 and 31 July 2000, respectively. The 19 July (31 July) event was characterized by north-northwesterly (westerly) advection of polluted (clean) air masses originating from Great Britain (the Atlantic Ocean). The aerosol number size distribution appeared to be composed mainly of two modes in the planetary boundary layer (accumulation and nucleation) and three modes in the surface layer (accumulation, nucleation, and coarse). The characteristics of the size distribution (modal radii and geometric dispersion) were remarkably similar on both days and very coherent with the aerosol optical parameters retrieved from lidar and nephelometer measurements. The city of Paris mainly produces aerosols in the nucleation mode (modal radius of ˜0.03 μm) that have little influence on the aerosol optical properties in the visible spectral range. The latter are largely dominated by the scattering properties of aerosols in the accumulation mode (modal radius of ˜0.12 μm). When the incoming air mass is already polluted (clear), the aerosol in the accumulation mode is shown to be essentially hydrophobic (hydrophilic) in the outgoing air mass.

  16. A preliminary investigation of segmentation and rime abilities of children who stutter

    PubMed Central

    Sasisekaran, Jayanthi; Byrd, Courtney T.

    2013-01-01

    The present study investigated segmentation and rhyme abilities, skills critical for phonological encoding, of children who stutter (CWS) and those who do not (CNS). Participants were 9 CWS (8 males and 1 female, Mean Age = 11.1, SD = 2.31) in the age range of 7 and 13 years and 9 age and sex matched CNS (Mean Age = 11.2, SD = 2.19). Participants performed two verbal monitoring tasks, phoneme and rhyme monitoring, in silent naming. Performances in the verbal monitoring tasks were compared to a neutral, nonverbal tone monitoring task. Additionally, the complexity of the phoneme monitoring task was varied such that participants had to monitor for singletons vs. consonant clusters. Repeated measures analysis of the response time data did not reveal significant differences between the groups in the three monitoring tasks. Analysis of the complexity data revealed a trend for slower monitoring of the consonant clusters in the CWS group compared to the CNS. Present findings do not support a deficit in segmentation and rhyme abilities in CWS, although there was some preliminary evidence of segmentation difficulties with increasing phonological complexity of the stimuli. PMID:23773673

  17. Computer Modeling of Time-Dependent Rime Icing in the Atmosphere,

    DTIC Science & Technology

    1983-01-01

    IDGTIER, NCOU.NCOUI ,NCOL.LJJ 435 C 436 COMMON ALPHAR.PI/AEROI/XE.YE/AER03/NCOUNCOL/ AERO2 /XC.YC.R.O.SI.CO 437 C 438 10 FORMAT(’OFOR EON. SOLN. IER=’.I3...XZI .YZI.F.N.NCOU.NCOLL, II 539 C 540 COMMON ALPHAR.PID/AERDI/XE,YE/AERO3/NCOU.NCOL/ AERO2 /XCYC.GAMMA.D 541 .Si.CO 542 ./GRID/XMIN.XMAX.YMIN.YMAX.XZ...COMMON ALPHAR.PI/AERO3/NCOU.NCOL/ AERO2 /XC.YC.GAMMA.D.SI.CO 2608 ./AIR/XP.YP.DELPSI ,TYPE 2609 C 2610 C IN X= 2611 C IN Y=COORDS. AT WHICH AIR VELOCITY

  18. Use of low-temperature scanning electron microscopy to observe icicles, ice fabric, rime and frost

    SciTech Connect

    Wergin, W.P.; Rango, A.; Erbe, E.F.

    1996-12-31

    Previous studies showed that low temperature scanning electron microscopy (SEM) can be used to record images of precipitated snow crystals, which collectively form structures that are commonly known as snowflakes. Information about the structure of snow crystals can be used to improve models that estimate the water equivalent of the winter snowpack. These models, which are based on satellite microwave data, have practical use in approximating the quantity of water that will be available for crop irrigation and hydroelectric power. Our previous success of using low temperature SEM to image snow crystals has encouraged us to utilize this technique for other types of frozen aqueous specimens.

  19. Phoneme, Grapheme, Onset-Rime and Word Analysis in Braille with Young Children

    ERIC Educational Resources Information Center

    Crawford, Shauna; Elliott, Robert T.; Hoekman, Katherine

    2006-01-01

    Two groups of sighted pre-school children were taught to name six braille letters: one group received phoneme instruction and the other grapheme instruction. Ten boys and ten girls (average age 4:5 years) participated. There was a statistically significant advantage for the phoneme group (Experiment 1). In a repeated measures design, 16 sighted…

  20. RIME: The Recoverable Item Management Evaluator. Volume II. Section I. Events Generator Programs.

    DTIC Science & Technology

    1980-05-01

    NKAXPEL 0 0 P 6 STOP S2 VRITI(6,13)"RZAD END-Of-rILE 00 C76 STOP NUW," ~~2 21 ~ VtTI(6,14)"!LI.ST UJ-RU~ Vkt )SM1 22 STOP -. 7 MEMORY EXPANDBD: USE...reparable generations (LDRGNT). If so, LDCONT is reset to LDRGNT. Next, similar calculations are performed for each SRU. Finally, the routine checks If the...of the above cases, appropriate counters of SRU events are reset after each of the Monte Carlo calculations to ensure that the correct probability

  1. The limitations of orthographic rime analogies in beginners' word reading: a reply to Goswami (1999)

    PubMed

    Bowey, J A

    1999-03-01

    U. Goswami (1999, Journal of Experimental Child Psychology, 72, 210-219) argues that the findings of J. A. Bowey, L. Vaughan, and J. Hansen (1998, Journal of Experimental Child Psychology, 68, 108-133) are uninterpretable. This paper examines each of Goswami's criticisms of the methodology employed by Bowey et al. (1998). None can explain the differential analogy and phonological priming effects reported by Bowey et al. More fundamentally, none can explain the critical finding of Bowey et al. that, when phonological priming effects are controlled, the size of the end analogy effect is no greater than that of beginning and medial vowel analogy effects. Furthermore, some of Goswami's criticisms cast considerable doubt on the generalizability of findings from her version of the clue word task. Copyright 1999 Academic Press.

  2. Phonemic Segmentation, Not Onset-Rime Segmentation, Predicts Early Reading and Spelling Skills.

    ERIC Educational Resources Information Center

    Nation, Kate; Hulme, Charles

    1997-01-01

    Gives children (ages 5+ to 9+) four tests of phonological skill to investigate relationships between these measures and their predictive relationship with reading and spelling ability. Finds performance at phonemic segmentation, rhyme sound categorization, and alliteration sound categorization improved with age, but all groups performed onset-rime…

  3. L'age sombre : du rayonnement cosmologique aux premieres étoiles

    NASA Astrophysics Data System (ADS)

    Priou, Denis

    2017-05-01

    The last scattering and recombination epoch is one of the most spectacular moments in the history of the Universe. The observation of the Cosmic Microwave Background (CMB), a relic of a very ancient past of the Universe, provides the astronomers with a huge quantity of information, by means of which they can build and test cosmological models describing the evolution of the Universe. By modeling the physical contents of the early Universe and the various interactions occuring during this epoch, it possible to describe very accurately the sequence of events that paved the way to the emission of the CMB and to the recombination of protons and electrons into neutral hydrogen atoms. In this paper are presented the main physical, theoretical and observational, ingredients that allows the astronomers to describe this key epoch and to determine when and how the recombination occurred.

  4. Effets de rayonnement sur les detecteurs au silicium a pixels du detecteur ATLAS

    NASA Astrophysics Data System (ADS)

    Lebel, Celine

    Two detection systems are using pixel silicon detectors in the ATLAS detector: the Pixel, which is the subdetector closest to the interaction point, and the MPX network. The activation of the materials present in the Pixel produced by radiation has been measured in two experiments which we performed at CERF (CERN) and NPI-ASCR (Czech Republic). These experimental studies of activation are compared with GEANT4 simulations. The results of these comparisons show that the simulation can predict the activities with a precision of an order of magnitude. They also show that GEANT4 fails to produce certain radioisotopes seen in the experimental activation studies. The contribution to background and the residual doses due to the desintegration of the radioisotopes produced by fast neutrons (category in which falls the expected average neutron energy of 1 MeV in ATLAS) are extrapolated to ATLAS conditions. It is found that this background in the ATLAS Pixel subdetector will be negligible and that the doses are well below safety concerns for detector manipulation during maintenance and repair periods. The radiation field also inflicts damages to the silicon detectors thus reducing their detection efficiency. A modified Hecht model is presented using an electric field description which includes the double junction effect and a small exponential component in areas usually considered without electric field. This model allows the description of the detection efficiency as a function of applied bias voltage and irradiation fluence for several types of silicon detectors irradiated by particles of different types and energies. On top of validating the Hecht model proposed in this thesis, the studies of the radiation damage on silicon detectors has allowed to conclude that the N1EL hypothesis has to be revised (study with different energies). Using the variation with irradiation fluence of the effective doping concentration and of the leakage current, it is shown that silicon detectors with a higher concentration of oxygen have a radiation hardness slightly improved for low-energy protons compared to standard silicon detectors. It is also demonstrated that the radiation hardness of the Mesa detectors is similar to standard detectors for proton and neutron irradiations. The MPX network includes fourteen pixel detectors located in the ATLAS detector and its cavern. Their goal is to perform, within the ATLAS detector and cavern, real-time measurements of the particle flux (type and energy), the doses and the background signal due to neutrons and photons. It will be shown that these detectors can indeed adequately detect several types of particles produced in ATLAS: photons, neutrons and charged particles. Using low-energy photons, the energy calibration of the comparator threshold is done. A phenomenological model is elaborated describing the charge sharing among pixels which appears when a heavy charged particle stops in the detector. Keywords: ATLAS, Pixel, detectors, silicon, radiation, activation, damage, detection efficiency

  5. MONOX: un nouveau spectrogoniomètre pour le rayonnement X mou et X-UV

    NASA Astrophysics Data System (ADS)

    André, J.-M.; Avila, A.; Barchewitz, R.; Benbalagh, R.; Delaunay, R.; Druart, D.; Fontaine, M.-F.; Ringuenet, H.

    2004-11-01

    Un spectrogoniomètre de laboratoire utilisant comme source un tube émettant des radiations caractéristiques dans le domaine X mou et X-UV a été développé au Laboratoire de Chimie Physique (CNRS/UPMC) dans le cadre de l'Action Coordonnée Optique du CNRS. L'appareil comprend un monochromateur de type “double-cristaux" équipé de miroirs multicouches ou de cristaux de grande période et un goniomètre θ-2θ . Il permet des mesures de pouvoir réflecteur et de diffusion de dispositifs optiques, en particulier de miroirs et réseaux multicouches. Dans un futur proche il sera aussi destiné à la caractérisation de nouvelles sources et de détecteurs X-UV. L'appareil peut aussi être utilisé comme spectromètre à cristal plan si l'anode est remplacée par l'échantillon à analyser. Différents exemples des possibilités offertes par cet instrument opérant en mode “réflectométrie" ou en mode “spectrométrie" sont présentés.

  6. Etude du mecanisme de predissociation de l'ion moleculaire de protoxyde d'azote par la mesure de l'energie cinetique des fragments de l'oxyde nitrique et de l'oxygene

    NASA Astrophysics Data System (ADS)

    Delisle, Claude

    La reaction N2 + O+ ↔ NO + + N, laquelle joue un role important dans la physique de la haute atmosphere, a ete le sujet de plusieurs etudes. Bien que cette reaction ait ete l'objet d'une quantite importante de travaux, ces derniers ne permettent toutefois pas de comprendre entierement le mecanisme d'un point de vue quantique, particulierement les niveaux d'energie excites des fragments qui permettent cette reaction. Puisque cette reaction n'est pas tres facile a reproduire en laboratoire, nous avons utilise la spectroscopie laser sur faisceaux d'ions rapides afin d'explorer les limites de dissociation de l'ion moleculaire intermediaire de cette reaction, a savoir l'ion N2O+. Le faisceau d'ions N2O+ rapides, apres excitation de l'ion moleculaire vers un niveau predissocie de l'etat A2Sigma+, se dissocie pour produire les fragments ioniques O+ et NO+. Par la mesure de la variation du nombre de fragments ioniques en fonction de l'energie cinetique des ions N2O+, nous avons enregistre les spectres de predissociation de l'ion N2O+. Lorsque c'etait possible, nous avons procede a l'analyse de ces spectres de dissociation afin d'en tirer les constantes moleculaires. Pour certaines des transitions rotationnelles intenses, nous avons mesure l'energie cinetique acquise par les fragments lors de la predissociation de l'ion N 2O+. Afin d'analyser les distributions en energie cinetique, nous avons developpe une simulation de l'experience en considerant, entre autres choses, la position des niveaux de vibration et de rotation des fragments diatomiques de chacune des limites de dissociation de N2O+. Les resultats de l'analyse sont exprimes en termes de population des niveaux de vibration des fragments diatomiques pour une distribution donnee de la population des niveaux de rotation des fragments. Les resultats ainsi obtenus, montrent que les fragments diatomiques sont produits dans des niveaux de vibration fortement excites. De tels niveaux d'excitation ne correspondent pas aux

  7. Education relative a l'environnement (ERE): Une etude des representations sociales et des pratiques educatives d'enseignants de science et technologie du secondaire en contexte de formation continue

    NASA Astrophysics Data System (ADS)

    Collard-Fortin, Ugo

    Le developpement des sciences/technologie a tres clairement contribue a ce que ce dernier domaine de savoirs jouisse d'une place de choix au sein de notre societe. Au-dela des progres de notre civilisation inherents a ce dernier developpement, cette croissance amena avec elle un lot d'ineluctables dommages collateraux, contribuant en corollaire a l'emergence de diverses problematiques environnementales inquietantes pour lesquelles les valeurs ainsi que le mode de fonctionnement de la societe occidentale contemporaine sont largement tributaires. C'est entre autres en reponse a cet etat de fait que la recente vague de reforme de l'Education conduisit a l'integration, dans les curricula de sciences/technologie, de contenus relavant d'education relative a l'environnement (ERE). Face au changement, les enseignants de sciences ont du s'approprier ce nouveau programme afm de l'enseigner a leurs eleves. Toutefois, l'analyse de la situation montre que les prescriptions du programme en matiere d'ERE ne se sont pas toujours traduites en de reelles actions dans la pratique. Le contexte de notre etude s'est interesse aux pratiques educatives de l'ERE ainsi qu'a la representation sociale qui en decoule. Notre recherche aborde plus specifiquement la problematique de la modification de ces derniers objets chez les enseignants de sciences et technologie du deuxieme cycle du secondaire. Pour y arriver, nous avons propose a un groupe de trois praticiens de participer a une activite, en communaute de pratique, de formation continue orientee autour de thematiques ERE. Cette recherche developpement, s'inscrivant dans un paradigme qualitatif/interpretatif, s'est appuyee sur une cueillette de donnees effectuee a partir d'entrevues semi-dirigees, d'observations en situation et d'un groupe de discussion, au debut et a la fm de la formation continue. Les donnees brutes ont ete soumises a une demarche d'analyse inductive et ont genere diverses categories etayant nos objets de recherche

  8. Measurement of x-ray laser beam divergence with CADIX, a time-resolved diagnostic tool using an insertable multilayer mirror

    NASA Astrophysics Data System (ADS)

    Reverdin, C.; Bourgade, J. L.; Bruneau, J.; Charret, M.; Desenne, D.; Dulieu, A.; Dumont, H.; Louis-Jacquet, M.; Sauneuf, R.; Schirmann, D.; Troussel, P.

    1992-10-01

    To study the x-ray laser beam deflection and divergence due to the refraction within the plasma, a specific diagnostic called CADIX has been developed at the Centre d'Etudes de Limeil-Valenton (CEL-V). When the beam refraction analysis is required a multilayer mirror is inserted on the x-ray laser output beam. It selects the lasing wavelengths and reflects them to an off-axis streak camera which records x rays as a function of time and angle. A detailed description of the instrument is presented including multilayer mirror calibration at the LURE (Laboratoire pour L'Utilisation du Rayonnement Synchrotron, Orsay, France). An experimental measurement on neon-like silver amplification is presented and analyzed with the response of the mirror. An important refraction effect is observed.

  9. Mars Science Laboratory Using Laser Instrument, Artist's Concept

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This artist's conception of NASA's Mars Science Laboratory portrays use of the rover's ChemCam instrument to identify the chemical composition of a rock sample on the surface of Mars.

    ChemCam is innovative for planetary exploration in using a technique referred to as laser breakdown spectroscopy to determine the chemical composition of samples from distances of up to about 8 meters (25 feet) away. ChemCam is led by a team at the Los Alamos National Laboratory and the Centre d'Etude Spatiale des Rayonnements in Toulouse, France.

    Mars Science Laboratory, a mobile robot for investigating Mars' past or present ability to sustain microbial life, is in development at NASA's Jet Propulsion Laboratory for a launch opportunity in 2009. The mission is managed by JPL, a division of the California Institute of Technology, Pasadena, Calif., for the NASA Science Mission Directorate, Washington.

  10. Quality of life assessment in Hodgkin's disease: a new comprehensive approach. First experiences from the EORTC/GELA and GHSG trials. EORTC Lymphoma Cooperative Group. Groupe D'Etude des Lymphomes de L'Adulte and German Hodgkin Study Group.

    PubMed

    Flechtner, H; Rüffer, J U; Henry-Amar, M; Mellink, W A; Sieber, M; Fermé, C; Eghbali, H; Josting, A; Diehl, V

    1998-01-01

    Previous reports from available trials have dealt with negative long-term sequelae in Hodgkin's disease (HD) survivors. There is, however, a lack of longitudinal data showing the correlation between outcome and various treatment-related variables and the process of re-adaptation into normal life after the end of treatment. In order to investigate the quality of life (QoL) of patients with HD in different dimensions during active treatment and follow-up and to identify longitudinal patterns of QoL dimensions during re-adaptation to normal life within the EORTC Lymphoma Cooperative Group and Groupe D'Etude des Lymphomes de L'Adulte (EORTC/GELA) and the German Hodgkin Study Group (GHSG), QoL assessment strategies were put into use over the last three to five years. Furthermore, the efforts aimed at obtaining cross-cultural comparisons between the participating countries and study groups (EORTC/GELA and GHSG). Within the randomised EORTC/GELA Trial 'H8' for clinical stage I-II HD which started in September 1993, patients receive a QoL questionnaire for completion at each follow-up visit during the first 10 years after the end of active therapy. The corresponding 'HD8' study of the GHSG employs the assessment of QoL during and after active treatment periods. Within both studies, the EORTC QLQ C30 is used for QoL assessment incorporated in the QLQ-S (quality of life questionnaire for survivors), which additionally addresses the aspects of fatigue/malaise, sexuality, specific side effects, and retrospective evaluation of treatment. In total the QLQ-S includes 45 questions on 14 functional, symptom, and fatigue scales, 15 additional single items, and 3 open questions. In addition to the longitudinal QoL assessment, the GHSG carried out cross-sectional QoL trials with all cured surviving patients from the past HD1-6 studies and a matched normal control sample employing the QLQ-S and the life situation questionnaire (LSQ), an instrument covering objective data from 45

  11. HBA1c: clinical and biological agreement for standardization of assay methods. Report by the experts of ALFEDIAM (Association de Langue Française pour lEtude du Diabète et des Maladies Métabolique) and SFBC (Société Française de Biologie Clinique).

    PubMed

    Gillery, P; Bordas-Fonfrède, M; Chapelle, J P; Drouin, P; Hue, G; Lévy-Marchal, C; Périer, C; Sélam, J L; Slama, G; Thivolet, C; Vialettes, B

    1999-09-01

    Glycohaemoglobin, and particularly haemoglobin A1c(HbA1c), assays have been used for many years to retrospectively evaluate the glycaemic control of diabetic patients. Cut-off values have been established for deciding treatment modifications. The techniques used in the laboratories however exhibit varying quality, and all of them are not yet standardized. The consequence is an under-utilization of this test, especially in non-hospital practice. In this context, working groups of Société Française de Biologie Clinique (SFBC), Association de Langue Française pour l'Etude du Diabète et des Maladies Métaboliques (ALFEDIAM) and Société Française d'Endocrinologie (SFE) have met together, in order to analyze the national status, and to propose practical recommendations for implementing a standardization process on the basis of international experiences. It is recommended to exclusively express results as HbA1c percentage, using methods standardized and certified by comparison to reference methods such as those using Diabetes Control and Complications Trial (DCCT) values. Simultaneously, contacts have been established with manufacturers, and the realisation of periodic quality control surveys was encouraged.

  12. Etude du comportement rheologique de suspensions colloidales

    NASA Astrophysics Data System (ADS)

    Yziquel, Florence

    Colloidal suspensions exhibit complex rheological behavior. The particles interact between themselves with forces of which the nature and magnitude depend on the surrounding medium. When the forces are strong enough, this organized structure which can be broken down, distorted or rearranged under shear flow. Hence, the suspension rheology depends greatly on the structure evolution during the flow. The main objective of this work was to propose a rheological model to describe the suspension behavior taking the structure evolution into account. To understand the rheological behavior of these systems, two different suspensions have been studied. The first system is a "model" suspension of fumed silica particles. These colloidal particles interact between themselves through hydrogen bonds with silanol groups on their surface inducing a network formation even at small mass fraction. The rheological properties of particles in suspension in polar and nonpolar media were studied as functions of size, concentration and surface treatment of particles. The rheological behavior, for small strain amplitude oscillatory flow, is strongly nonlinear. These nonlinear viscoelastic properties have been interpreted in terms of dissipated energy and attributed to the network breakdown. The experimental data have been compared with Coussot and Oldroyd modified models predictions. These two models only describe qualitatively the rheological behavior of fumed silica suspensions in nonpolar media. The second system studied here is a coating color. This concentrated suspension is mainly composed by kaolin particles sterically stabilized by water-soluble polymer adsorbed on their surface. The steady shear viscosity and the dynamic properties have been studied as a function of polymer concentration for two different water-soluble polymers. It was shown that the rheological properties are controlled by the structure evolution under shear flow. A structural model has been proposed to describe the rheological behavior of coating colors. The nonlinear viscoelasticity was attributed to the motion of the equilibrium particle position. A model based on the network theory has been proposed to describe the rheological behavior of both suspensions. The proposed model is based on a modified upper convected Jeffreys model coupled with a kinetic equation describing the structure evolution under flow. Three kinetic equations have been examined. The first one depends on the second invariant of the rate-of-strain tensor, the second, on the first invariant of the stress tensor and the last one, on the rate of dissipated energy. These kinetic equations coupled with Jeffreys model describe fairly well the non linear viscoelastic behavior of the fumed silica suspensions and the coating colors. The effect of frequency, in the nonlinear domain, is a critical test to assess the proposed model validity. Contrary to homogeneous polymers, the critical strain decreases with increasing frequency. Therefore, the stress-dependent model is inappropriate for predicting the rheological behavior of suspensions. The energy-dependent model seems to be the best adapted. Nevertheless, this model, as the two others, cannot predict the different dynamic properties measured here with the same parameter values.

  13. Predicting Growth of Nonword Reading and Letter-Sound Knowledge Following Rime- And Phoneme-Based Teaching

    ERIC Educational Resources Information Center

    Savage, Robert; Carless, Sue

    2004-01-01

    The present study sought to extend a recent study by Savage, Carless and Stuart, by looking at the pre-test phonological skills that predicted improvements in letter-sound knowledge and nonword reading. Results showed overall that phoneme manipulation predicted improvements in nonword reading and letter-sound knowledge even when pre-test scores on…

  14. Étude structurale par rayonnement synchrotron de superréseaux d'oxydes pérovskites

    NASA Astrophysics Data System (ADS)

    Nemoz, M.; Dooryhee, E.; Hodeau, J.-L.; Dubourdieu, C.

    2004-11-01

    Perovskite oxides are analyzed by using high resolution synchrotron radiation diffraction. The diffraction profiles are fitted, taking into account the structural and chemical disorders which depart from the ideal defect-free superlattice. Two types of superlattices, (BaTiO{3}/SrTiO{3}){15} and (La{0.7}Sr{0.3}MnO{3}/SrTiO{3}){15}, are synthesized by metal-organic chemical vapor deposition (MOCVD) on <{001}> oriented Nb-doped SrTiO{3} substrates. High-angle diffraction data show the excellent crystallinity and epitaxy of the films. For the (BaTiO{3}/SrTiO{3}){n} multilayers we observe a pseudo tetragonal symmetry with no difference between a and b axes, and they present a significant strontium/baryum interdiffusion. The (La{0.7}Sr{0.3}MnO{3}/SrTiO{3})n multilayers and their substrates almost have the same a=b parameter. Along the c axis, La{0.7}Sr{0.3}MnO{3} and SrTiO{3} have different lattice parameters. The crystallographic coherence of the stacking is higher in these samples.

  15. Trends in incidence and early outcomes in a Black Afro-Caribbean population from 1999 to 2012: Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents Vasculaires Cérébraux II Study.

    PubMed

    Olindo, Stephane; Chausson, Nicolas; Mejdoubi, Mehdi; Jeannin, Severine; Rosillette, Karine; Saint-Vil, Martine; Signate, Aissatou; Edimonana-Kaptue, Mireille; Larraillet, Veronique; Cabre, Philippe; Smadja, Didier; Joux, Julien

    2014-11-01

    Seldom studies are available on trends in stroke incidence in blacks. We aimed to evaluate whether stroke risk prevention policies modified first-ever stroke incidence and outcomes in the black Afro-Caribbean population of Martinique. Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents Vasculaires Cérébraux (ERMANCIA) I and II are 2 sequential prospective population-based epidemiological studies. There have assessed temporal trends in first-ever stroke incidence, risk factors, pathological types, and early outcomes in the black Afro-Caribbean population of Martinique comparing two 12-month periods (1998-1999 and 2011-2012). Crude and age-standardized incidence and 30-day outcomes for stroke in the 2 study periods were compared using Poisson regression. We identified 580 and 544 first-ever strokes in the 2 studies. World age-standardized incidence rates decreased by 30.6% in overall (111 [95% confidence interval, 102-120] versus 77 [95% confidence interval, 70-84]). Rate decline was greater in women than in men (34% versus 26%) particularly in women aged 65 to 74 years (-69%) and 75 to 84 years (-43%). Frequencies of hypertension and diabetes mellitus were unchanged, whereas dyslipidemia, smoking, and atrial fibrillation significantly increased. Only ischemic stroke types showed significant rate reduction in overall and in women, incidence rate ratio (95% confidence intervals) of 0.69 (0.50-0.97) and 0.61 (0.42-0.88), respectively. The overall 30-day case-fatality ratio remained stable (19.3%/17.6%), whereas a better 30-day outcome was found (modified Rankin Score, ≤2 in 47%/37.6%; P=0.03). Over 13 years, there has been a significant decrease (30.6%) in the age-specific first-ever stroke incidence in our Afro-Carribean population. Although prevention policies seem effective, we need to focus on new risk factors limitation and on male population adherence to prevention program. © 2014 American Heart Association, Inc.

  16. Elaboration de revetements nanocomposites avec des proprietes superhydrophobes, semi-conductrices et photocatalytiques

    NASA Astrophysics Data System (ADS)

    Madidi, Fatima Zahra

    Les lignes aeriennes de transport et de distribution de l'energie electrique sont souvent exposees a diverses contraintes. Parmi celles-ci, la pollution des isolateurs constitue l'un des facteurs de premiere importance dans la fiabilite du transport d'energie. En effet, la presence de pollution sur les isolateurs lorsqu'elle est humidifiee entraine la diminution de leur performance electrique en favorisant l'apparition d'arcs de contournement. De telles pannes peuvent parfois causer des impacts socioeconomiques importants. Par ailleurs, le developpement de nouveaux revetements pour ces isolateurs peut s'averer un moyen efficace pour les proteger contre l'apparition de l'arc de contournement. Les revetements superhydrophobes ont fait l'objet de nombreuses etudes au cours de ces dernieres annees. Ces surfaces sont preparees en combinant une rugosite nano-microstructuree avec une faible energie de surface. En outre, de telles surfaces ont de nombreuses applications si elles sont durables et n'ont pas d'effets nocifs sur l'environnement. L'objectif principal de la presente etude vise d'abord l'elaboration de revetements superhydrophobes, puis l'etude de leur duree de vie, leurs proprietes dielectriques et photocatalytiques. Une grande variete de materiaux a faible energie de surface peuvent etre utilises pour le developpement de ces revetements. Dans cette recherche, le caoutchouc de silicone (CS) est employe car il presente de nombreuses proprietes, notamment une forte hydrophobie, une resistance aux rayonnements ultraviolets, et une bonne tenue au feu sans degagement de produits toxiques. Toutefois, le point faible de ces materiaux est la degradation de leurs proprietes hydrophobes. Afin d'ameliorer certaines proprietes du caoutchouc de silicone, des nanoparticules seront additionnees au polymere de base. La technique d'elaboration des revetements consiste a ajouter des nanoparticules de dioxyde de titane (TiO2) au polymere de base, par des methodes ayant un

  17. Studies in vivo by electron spin resonance of free radical mechanisms implicated in UV-induced skin photocarcinogenesis.

    PubMed

    Valavanidis, A; Rallis, M; Papaioannou, G; Xenos, K; Katsarou, A

    1995-08-01

    Synopsis Solar ultraviolet radiation (UVR) is implicated in many types of skin damage, such as photodermatoses, photoageing, erythema, pigmentation, skin cancer etc. Free radicals and reactive oxygen species are considered to play an important role in cutaneous photocarcinogenesis. But skin is endowed with photoprotective agents, namely melanins and antioxidant enzymatic and non-enzymatic mechanisms. In this study we describe the in vivo electron spin resonance (ESR) signals of melanins after UVR exposure, using skin specimens of various types of mice, which were taken from different parts of their bodies. The ESR signals were used as a model for testing the antioxidant properties of butylated hydroxyanisole, tocopherol acetate, and octyl p-methoxycinnamate with butyl methoxy dibenzoyl methane and superoxide dismutase (SOD). Additional UVB radiation was applied to the skin samples in situ (in the cavity of the ESR spectrometer). Suppression of ESR signals of melanins was observed in all cases. Etudes in vivo par resonance paramagnetique electronique, après exposition au rayonnement UV, des méchanismes radicalans impliqués a la photocarcinogénèse cutanée.

  18. Black Hole Event Horizons and Advection-Dominated Accretion

    NASA Technical Reports Server (NTRS)

    McClintock, Jeffrey; Mushotzky, Richard F. (Technical Monitor)

    2002-01-01

    The work supported in part by this grant is part of a larger program on the detection of black hole event horizons, which is also partially supported by NASA grant GO0-1105A. This work has been carried out primarily in collaboration with Dr. M. Garcia and Prof. R. Narayan at the Harvard-Smithsonian Center for Astrophysics and with D. Barret and J. Hameury at Centre d'Etude Spoliate des Rayonnements, France. Our purpose is to confirm the existence of black-hole event horizons by comparing accreting black holes to secreting neutron stars in quiescent X-ray novae. Such a comparison is feasible because black holes and neutron stars are both present in similar environments in X-ray novae. Our second purpose is to assess the nature of accretion flows onto black holes at very low mass transfer rates. Observations of some XMM targets are still pending, whereas most of the Chandra observations have been completed. We anticipate further publications on this work in the future.

  19. The Hard X ray Telescope Mission

    NASA Technical Reports Server (NTRS)

    Gorenstein, Paul

    1997-01-01

    The Hard X Ray Telescope (HXT) was selected for study as a possible new intermediate size mission for the early 21st century. Its principal attributes are: (1) multiwavelength observing with a system of focussing telescopes that collectively observe from the UV to over 1 MeV, (2) much higher sensitivity and much better angular resolution in the 10100 keV band, and (3) higher sensitivity for detecting gamma ray lines of known energy in the 100 keV to 1 MeV band. The institutions collaborating in the study are: Smithsonian Astrophysical Observatory, Marshall Space Flight Center, Naval Research Laboratory, Goddard Space Flight Center, Argonne National Laboratory, Danish Space Research Institute, Osservatorio Astronomica di Brera (Merate), and Centre d'Etudes Spatiale des Rayonnements (Toulouse). The instrumentation includes several grazing incidence double conical telescopes with multilayer coatings that focus up to 100 keV and a single Laue crystal telescope that functions to 1 MeV. The detectors are CCDs, and germanium, and/or CdZnTe position sensitive arrays.

  20. Search for Heavy Top-like Quarks t-rime ---> Wq Using Lepton Plus Jets Events in 1.96-TeV p anti-p Collisions

    SciTech Connect

    Lister, Alison; /UC, Davis

    2008-10-01

    We present the results of a search for a new heavy top-like quark, tprime, decaying to a W boson and another quark using the CDF II Detector in Run II of the Tevatron ppbar collider. New top-like quarks are predicted in a number of models of new physics. Using a data sample corresponding to 2.8 fb-1 of integrated luminosity we fit the observed spectrum of total transverse energy and reconstructed quark mass to a combination of background plus signal. We see no evidence for tprime production, so use this result to set limits on the tprime tprimebar production cross section times the branching ratio of tprime to Wq and infer a lower limit of 311 GeV/c2 on the mass of the tprime at 95% CL.

  1. The Enigma of the Origin of Round, Deep, Rimed Lakes in the Russian Heartland-Was Lake Smerdyachie Formed During the Impact of an Extraterrestrial Body?

    NASA Astrophysics Data System (ADS)

    Abbott, D. H.; Gusiakov, V. K.; Kiselev, A.; Amelin, I. I.; Breger, D. L.; McCafferty, P.

    2014-12-01

    The heartland of Russia has many enigmatic deep lakes. Shallow lakes have a more obvious origin, perhaps as kettle lakes, oxbow lakes or subsidence features. Deep lakes, particularly round lakes with partial or complete rims are more problematic. Traditionally, round or nearly round lakes with rims are candidates for Holocene age impact structures. The problem is that there are too many such lakes in the Russian heartland- a minimum of 15 deep, round lakes with diameters between 0.2 and 3 km. Even with a possibly increased impact rate during the Holocene, these deep lakes would represent the entire budget of Holocene impacts concentrated in one small region of the Earth. We examine here Lake Smerdyachie, a previously proposed impact lake. Smerdyachie is perfectly round with a raised rim. It has a diameter of about 350 meters and a maximum water depth of over 30 m. The basement at Smerdyachie is at~40 meters depth. It consists of Carboniferous age carbonate rock with fossils of brachiopods, crinoids and gastropods. The overlying material consists of unconsolidated, sand and silt-sized, quartz-rich sediments. We found clasts of brachiopod, crinoid and gastropod-bearing Carboniferous carbonate rock up to 32 cm in diameter on the SE rim of Smerdyachie. These clasts are present over about 1/3 of the total circumference of the lake. We also made panned concentrates of the sediment on the rim. To the NW, the concentrated sediment has a negative magnetic susceptibility (-0.07 to -0.03 cgs units), consistent with a higher concentration of pulverized limestone. To the SE, the sediment has a positive magnetic susceptibility (0.06 to 0.35 cgs units). The areas of positive magnetic susceptibility lie on the SE two-thirds of the rim of the lake. The highest susceptibility value is from the sample taken closest to the lake shoreline on the SE rim. This spatial distribution of susceptibility could mean that there is a higher concentration of iron rich material on the SE side of the lake. To test this hypothesis, we plan to remove the calcium carbonate from our previously measured samples and then to remeasure their magnetic susceptibility. We will then examine the material with the highest magnetic susceptibility for possible impactor fragments.

  2. Large Grain Instruction and Phonological Awareness Skill Influence Rime Sensitivity, Processing Speed, and Early Decoding Skill in Adult L2 Learners

    ERIC Educational Resources Information Center

    Brennan, Christine; Booth, James R.

    2015-01-01

    Linguistic knowledge, cognitive ability, and instruction influence how adults acquire a second orthography yet it remains unclear how different forms of instruction influence grain size sensitivity and subsequent decoding skill and speed. Thirty-seven monolingual, literate English-speaking adults were trained on a novel artificial orthography…

  3. Large Grain Instruction and Phonological Awareness Skill Influence Rime Sensitivity, Processing Speed, and Early Decoding Skill in Adult L2 Learners

    ERIC Educational Resources Information Center

    Brennan, Christine; Booth, James R.

    2015-01-01

    Linguistic knowledge, cognitive ability, and instruction influence how adults acquire a second orthography yet it remains unclear how different forms of instruction influence grain size sensitivity and subsequent decoding skill and speed. Thirty-seven monolingual, literate English-speaking adults were trained on a novel artificial orthography…

  4. Equivalents dynamiques pour l'etude de la stabilite transitoire

    NASA Astrophysics Data System (ADS)

    El Aouni, Wassil

    Today's transient stability (TS) studies are a necessary tool to predict power systems behavior after the occurring of huge faults (ex: short-circuit, generator's lost, etc.). These studies allow us to plan the necessary actions to take in order to maintain the required levels of availability and quality of the electricity production. However, because of the fast increase of the size and the complexity of the power systems, these (TS) studies require higher duration and efforts for their calculations to be processed. The problem of this thesis is therefore: How to reduce the (TS) programs duration and calculation efforts while keeping the precision of their results? In order to resolve this problem, an initial literature review was performed. This literature review allowed us to notice that power systems reduction techniques used to decrease duration of (TS) simulation programs were designed long time ago. These techniques have the common goal of reducing the (TS) simulation duration and effort while keeping the same original power system dynamic behavior. This literature review leaded us also to choose a four steps power system reduction method: In the first step, the power system internal and external zones are chosen. In the second step the power system external zone generators able to be aggregated together are identified using the slow coherency method in addition to a time domain (TS) simulation. In the third step, dynamic parameters of the equivalent reduced network machines are derived using the structure preserving method which has the advantage of being useful for both classical and detailed power systems models. In the fourth step, the equivalent power system admittance matrix is processed using Zhukov method. The method proposed to resolve the problem of this thesis was afterwards implemented under Matlab(c) functions format. These aggregation functions were validated in the case of (TS) and (SIME) programs for the two following test network: " New England " 10 machines 39 buses under classical and detailed models, and the IEEE 50 machines 145 buses under classical model. PSSE(c) industrial software was also used in order to validate the results. The designed aggregation functions allowed us to have a significant increase of the speed of the (TS) and (SIME) programs while keeping a good accuracy of their outputs.

  5. Etude du champ magnetique dans les nuages moleculaires

    NASA Astrophysics Data System (ADS)

    Houde, Martin

    2001-12-01

    Ce travail est une étude du champ magnétique duns l'environnement circumstellaire des étoiles jeunes. Il a pour origine la certitude qu'avait l'auteur qu'il se devait d'être possible de détecter la présence d'un champ magnétique, et de possiblement le caractériser, par le biais d'observations de profils spectraux d'espèces moléculaires ioniques. Il en découle donc qu'un des buts principaux était de prouver que cela est effectivement possible. La thèse comporte alors des éléments théoriques et expérimentaux qui sont à la fois complémentaires et intimement liés. L'aspect théorique est basé sur l'interaction mutuelle que des particules neutres et chargées peuvent avoir l'une sur l'autre daps un plasma faiblement ionisé comme ceux existants daps les nuages moléculaires sites de formation stellaire. Il appert que la présence d'un champ magnétique a un effet direct sur le comportement des ions (via la force de Lorentz) et indirect sur les molécules neutres (via les nombreuses collisions entre les deux types de particules). Une telle interaction est, comme il est maintenant bien connu, présente dans les premières étapes de la formation dune étoile. Il s'agit bien sûr de la diffusion ambipolaire. Nous montrerons qu'il existe cependant un autre type de diffusion, jusqu'ici inconnue, qui se manifeste plus tard au tours de l'évolution des nuages moléculaires. Celle-ci peut avoir un effet dramatique sur l'apparence des profils spectraux (de rotation moléculaire) des espèces ioniques lorsque comparés à ceux qu'exhibent des espèces neutres coexistantes. Mais pour ce faire, il doit y avoir existence de mouvements organisés (des flots ou jets) de matière ou encore la présence de turbulence dans les régions considérées. Une distribution de vélocité du type maxwellienne ne révèlera pas la présence du champ magnétique. Les observations, qui ont pour but de confirmer la théorie, se situent dans le domaine des longueurs d'ondes millimétriques et sous- millimétriques. Plusieurs espèces moléculaires furent détectées dans un échantillon significatif de nuages moléculaires. L'effet prédit fut confirmé et ce peu importe si les raies observées sont opaques ou transparentes. Dans le dernier chapitre, nous considérerons une application intéressante où nous utiliserons la manifestation de cet effet (ou son manque) pour vérifier l'alignement préférentiel des flots bipolaires, qui accompagnent souvent la présence de proto- étoiles, avec le champ magnétique local.

  6. Etude des effets du martelage repetitif sur les contraintes residuelles

    NASA Astrophysics Data System (ADS)

    Hacini, Lyes

    L'assemblage par soudage peut engendrer des contraintes residuelles. Ces contraintes provoquent des fissurations prematurees et un raccourcissement de la duree de vie des composants. Dans ce contexte, le martelage robotise est utilise pour relaxer ces contraintes residuelles. Trois volets sont presentes: le premier est l'evaluation des effets des impacts unitaires repetes sur le champ de contraintes developpe dans des plaques d'acier inoxydable austenitique 304L vierges ou contenant des contraintes residuelles initiales. Dans la deuxieme partie de ce projet, le martelage est applique grace au robot SCOMPI. Les contraintes residuelles induites et relaxees par martelage sont ensuite mesurees par la methode des contours, qui a ete adaptee a cet effet. Dans la troisieme partie, le martelage est modelise par la methode des elements finis. Un modele axisymetrique developpe grace au logiciel ANSYS permet de simuler des impacts repetes d'un marteau elastique sur une plaque ayant un comportement elastoplastique.

  7. Etude thermo-aeraulique d'une piscine interieure

    NASA Astrophysics Data System (ADS)

    Guerfala, Nasreddine

    Les grands espaces fermés (amphithéâtres, supermarchés, gymnases et piscines) jouent un rôle essentiel dans l'économie et la société canadienne mais n'assurent pas nécessairement le confort thermique et la bonne qualité de l'air intérieur. En outre, leur consommation énergétique demeure très élevée. Plus spécifiquement, les piscines intérieures présentent certaines particularités telles qu'une humidité relative élevée, une température contrôlée de l'eau et une condensation possible sur les parois ce qui rend la tâche d'assurer le confort des baigneurs encore plus difficile. Rares sont les études réalisées pour ce type de bâtiment malgré l'existence de pistes d'optimisation de la consommation énergétique et l'amélioration de la qualité d'air intérieur. Dans cette optique, ce mémoire présente une étude thermo-aéraulique réalisée sur la piscine intérieure de l'Université Bishop's (Sherbrooke, Canada). La simulation numérique a été effectuée en utilisant le logiciel TRNSYS. L'approche adoptée pour la modélisation est la méthode zonale qui découpe l'espace de travail étudié en plusieurs zones fictives tout en calculant les caractéristiques thermo-aérauliques (température, pression, nombre de changement d'air par heure). D'autre part, une validation expérimentale en situations réelles est mise en œuvre au sein de cette piscine moyennant un dispositif expérimental spécifique. Ce dernier a été conçu spécialement pour s'adapter aux caractéristiques du milieu (hauteur du bâtiment, présence de l'eau et forte humidité) afin de mesurer la température, la pression et la vitesse de l'air dans plusieurs endroits significatifs de la piscine. Cette étude développe un outil de calcul capable de prédire les températures de différentes zones thermiques et des surfaces de l'enveloppe du bâtiment d'une part et de calculer le débit massique de l'air entre les zones ainsi que le nombre de changement d'air par heure pour en déduire le confort thermique des occupants d'autre part. De plus, elle fournit une base de données des mesures extensives de température, humidité relative et de vitesse de l'air prises à l'été 2012 qui ont permis de valider les simulations numériques réalisées. Enfin, une étude paramétrique a été menée pour savoir l'effet de la modification de certains paramètres tel que les caractéristiques des systèmes de ventilation et chauffage sur la consommation énergétique du bâtiment et le confort thermique des occupants. Par conséquent, des recommandations ont été proposées. Les résultats ainsi obtenus permettront aux industriels d'améliorer les performances énergétiques des piscines intérieures et donneront des solutions constructives pour les concepteurs de ce type de bâtiment. Mots clés : Grands espaces fermés, piscine intérieure, méthode zonale, confort thermique, qaulité d'air intérieur, efficacité énergétique.

  8. Etude par spectroscopie raman du chlorhydrate de cocaine.

    PubMed

    Gamot, A P; Vergoten, G; Fleury, G

    1985-05-01

    Raman spectra of cocaine hydrochloride in the polycrystalline state and in saturated aqueous solutions have been recorded at room temperature from 0 to 4000 cm(-1) and at 9 K from 0 to 200 cm(-1) (only for the polycrystalline state). They show that cocaine can be characterized by the following proposed assignments. For the tropane nucleus the frequencies 851 and 786 cm(-1) (piperidine) and 896, 870 cm(-1) (pyrrolidine); these frequencies are assigned to ring carbon stretching vibrations V(C-C) Bands for the ester functional groups can be observed at 1713 cm(-1) (v(CO)) and 1203 cm(-1) (v((C-O-O)). The benzene nucleus is also important in characterization of cocaine hydrochloride because of its bands at 616, 990, 1000, 1026 and 1596 cm(-1). Special reference is made first to the work in the low-frequency range at room temperature and 9 K and secondly to the polarization studies of saturated aqueous solutions in the range 700-1726 cm(-1). The results constitute a pool of analytical characteristics which can be used for toxicological investigations, and also show all the possibilities of Raman spectroscopy in this field.

  9. Etude RICH Nursing. Plus de connaissances et de preuves scientifiques

    PubMed Central

    SCHUBERT, MARIA

    2009-01-01

    L’importance et la validité des résultats de l’étude RICH-Nursing* ont été récemment mises en cause par certains milieux, ce qui a provoqué certaines incertitudes chez les infirmières. Les auteurs reviennent sur l’impact actuel de cette étude et évoquent les perspectives d’avenir. PMID:25221376

  10. Etude numerique du sillage tourbillonnaire d'une eolienne

    NASA Astrophysics Data System (ADS)

    Sibuet Watters, Christophe

    Cette these formalise le concept de la surface actuatrice (SA) et en presente l'implantation dans deux methodes de mecanique des fluides assistee par ordinateur (CFD) bidimensionnelle (2D) et tridimensionnelle (3D), la validation et l'application au probleme de modelisation du sillage tourbillonnaire d'une eolienne. En termes cinetiques, une SA est une nappe tourbillonnaire qui resulte en une discontinuite de vitesse tandis qu'en termes dynamiques, elle est associee a un systeme de forces dont la composante dans la direction normale a la SA resulte en une discontinuite de pression. Les methodes CFD utilisees sont des methodes aux volumes finis, adaptees pour prendre en compte l'action de la SA sur l'ecoulement. L'approche de la SA est validee pour des problemes 2D: aile infinie et disque actuateur, ainsi que pour le probleme 3D de l'aile en translation (aile effilee), avant d'etre appliquee a plusieurs eoliennes.

  11. Etude de la resistance en fatigue des materiaux bitumineux

    NASA Astrophysics Data System (ADS)

    Touhara, Radouen

    The goal of this research program is to evaluate and characterize the fatigue behaviour of two GB20 hot mix asphalt made with two different bitumen. One of them is made in laboratory with a straight-run PG58-28 bitumen, while the second mix was made in an asphalt plant with a PG64-28 bitumen. Two characterization tests, in homogeneous conditions, done in traction/compression on cylindrical specimens are used in this study. First, a complex modulus test performed in the linear viscoelasticity (LVE) domain is used to characterize the mixes and second, a fatigue test is done to evaluate the mixes performances. The fatigue tests were done in strain controlled at different amplitude. All fatigue tests were performed at 10Hz, but at different temperatures (10, 20 and 30°C) in order to evaluate the effect of the temperature on the fatigue behaviour of those mixes. In this document, the results are presented, and the analysis of the results as a function of the grade of bitumen, the tests’ temperature and the dispersion of the results is performed. Also, the DGCB method is applied to the fatigue results to calculate the rate of damage per cycle followed by a study of the different failure criteria (Nf) to predict the fatigue life of asphalt mixes. Keywords: bituminous materials, fatigue, complex modulus, Damage.

  12. Mathematics Comparison Study = Etude Comporative Portant Sur les Mathematiques.

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Curriculum Standards Branch.

    At the request of the Council of Ministries of Education, Canada (CMEC), Alberta Learning conducted this Mathematics Comparison Study. The focus of this study is from Kindergarten to Grade 12. All provinces and territories were invited to participate, and only the Quebec region declined. Participating regions were invited to send a representative…

  13. Systeme complet d'interferometrie radar: Etude de cas

    NASA Astrophysics Data System (ADS)

    Vincent, Frederic

    2002-09-01

    La recherche realisee a porte sur la mise au point de plusieurs ameliorations dans la chaine de traitement interferometrique necessaire pour pouvoir appliquer l'interferometrie radar (InROS) a des problemes d'interets majeurs au Quebec. Ainsi, la mesure de la deformation du sol et la creation de modeles numeriques d'altitude (MNA) par InROS en zone de coherences variables ont ete explorees au cours de cette recherche. Les faibles taux de deformation et les petites dimensions spatiales des zones affectees, les rapides variations des conditions climatiques et la presence de vegetation dense sont les principaux facteurs responsables de l'echec de l'InROS pour la mesure des deformations de glissements de terrain au Quebec. L'InROS s'est par contre averee etre un outil puissant pour le suivi des mouvements de glace sur les cours d'eau nordiques pour la securite des populations riveraines et pour la navigation fluviale. Une methode de fusion de MNA InROS de differentes configurations de prises de vue d'images en fonction des caracteristiques locales de pente et de coherence a ete developpee afin d'ameliorer la qualite des MNA InROS en zone de fortes variations de coherence. Finalement, une methode de correction des effets atmospheriques qui affectent les interferogrammes, basee sur l'acquisition simultanee de donnees GPS et de donnees radar, a aussi ete developpee au cours de cette recherche.

  14. Etudes physiques des mélanges eau-cryoprotecteurs

    NASA Astrophysics Data System (ADS)

    Vassoille, R.; Perez, J.

    The aim of the following review is to present the most important studies concerning the physical properties of water-solutes mixtures used in cryobiology. Cryobiology is a branch of biology which deals with the very low temperature behaviour of cells. This technique is developed today in several directions. The creation of banks of cells and perhaps in a short time of small organs, is the purpose of much research in this domain. Before freezing, living cells are generally put in a solution containing one or more solutes. The role of these solutes is to protect the cells against damage due to crystallization of water (cryoprotectors). The mechanisms of cryoprotection are not well known ; nevertheless the vitreous state formation during cooling is often invoked. So, it is possible to avoid crystallization damage such as mechanical strain (due to an increase of volume of about 10 %) and salt effects (due to osmotic pressure). The conditions in which the vitreous state is obtained, maintained during cooling, storage at low temperature and rewarming can be defined by physical studies presented in the following review. Le présent travail est essentiellement une revue bibliographique des principales études physiques qui ont été réalisées avec des solutions de composés habituellement employés en cryobiologie. La cryobiologie est une branche de la biologie qui s'intéresse au comportement des cellules à basse température. Cette discipline est actuellement en plein développement dans des domaines très divers. Son principal but est la création de banques de cellules de plus en plus complexes avec comme perspective la conservation des organes. Les cellules vivantes sont généralement placées avant congélation dans une solution contenant divers composés dont le rôle est de protéger les cellules contre les effets de la cristallisation de l'eau. L'action protectrice de ces cryoprotecteurs est encore mal connue; cependant, la formation d'un état vitreux lors du refroidissement est souvent invoquée. Ainsi, il est possible d'éviter les dommages liés à la cristallisation : contrainte mécanique due à l'augmentation de volume, effets de sel dus à l'existence d'un gradient de pression osmotique de part et d'autre de la membrane cellulaire. Les conditions d'obtention et de maintien de cet état vitreux lors des opérations de congélation peuvent être définies par des études physiques dont nous proposons une revue.

  15. Etude CCD de 11 variables suspectes du Serpent

    NASA Astrophysics Data System (ADS)

    Chantegros, Hervé

    2005-12-01

    Hervé Chantegros has studied 11 stars in Serpens, suspected, long ago by Antoine Brun to be variable. Those stars were followed from April 24 to October 4, with a CCD. The results are given here, some of those stars seem to vary up to 1.5 mag large (possibly seen visually). Those stars need more study from amateurs to be classified.

  16. Etude des systèmes protoplanétaires

    NASA Astrophysics Data System (ADS)

    Augereau, Jean-Charles

    2000-11-01

    Les disques de poussières et de gaz autour des étoiles rejoignant la Séquence Principale sont les sites de formation des planètes extra-solaires dont l'existence s'est vu confirmée récemment. Cette thèse aborde l'étude de la poussière des environnements circumstellaires. Elle associe des observations spatiales à haute résolution angulaire, la modélisation des propriétés physico-chimiques des poussières et leur comportement optique, la modélisation des disques optiquement fins et la dynamique des planétésimaux à l'origine des grains observés autour des étoiles âgées. Les images obtenues avec le Télescope Spatial Hubble révèlent deux nouveaux disques circumstellaires autour des étoiles HD 141569 et HD 100546, parfois classées dans la catégorie des étoiles de Herbig. Bien que les systèmes présentent des âges proches (~10 millions d'années), les morphologies très différentes des disques mettent en évidence la difficulté pour élaborer un scénario unique d'évolution des systèmes protoplanétaires. L'anneau fin de poussières autour de HR 4796A, une étoile d'âge similaire aux précédentes, est marginalement résolu depuis le sol. La modélisation complète de ce disque permet de reproduire l'ensemble des observations disponibles. Ces résultats impliquent la présence de planétésimaux, à un âge aussi peu avancé, pour repeupler le disque en poussières poreuses et essentiellement amorphes qui sont soufflées par la pression de radiation. Une modélisation dynamique du prototypique disque autour de β Pictoris est proposée. Associée à une description réaliste du comportement optique des grains, cette approche reproduit les caractéristiques générales du disque ainsi que des asymétries plus fines en supposant la présence d'une planète dans un disque de planétésimaux et en tenant compte des effets différentiels de la pression de radiation sur les grains. Enfin, le modèle de disques que j'ai développé est exploité dans le but d'optimiser l'utilisation des nouveaux instruments.

  17. Mathematics Comparison Study = Etude Comporative Portant Sur les Mathematiques.

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Curriculum Standards Branch.

    At the request of the Council of Ministries of Education, Canada (CMEC), Alberta Learning conducted this Mathematics Comparison Study. The focus of this study is from Kindergarten to Grade 12. All provinces and territories were invited to participate, and only the Quebec region declined. Participating regions were invited to send a representative…

  18. Potentialités des lasers à fibre dans la génération de rayonnement cohérent UV

    NASA Astrophysics Data System (ADS)

    Martel, G.; Hideur, A.; Ortaç, B.; Lecourt, J.-B.; Chédot, C.; Brunel, M.; Chéron, B.; Limpert, J.; Tunnermann, T.; Grelu, Ph.; Gicquel-Guézo, M.; Labbé, C.; Loualiche, S.; Roussignol, Ph.; Sanchez, F.; Leblond, H.

    2006-12-01

    Le premier laser à fibre dopé aux ions de terres rares fonctionna au tout début des années 60. Il fournissait quelques milliwatts autour de 1 μm. Les décades suivantes virent très peu d'améliorations tant du côté des laboratoires que du point de vue industriel. La dernière décennie (1995/2005) vit se concrétiser la seconde révolution des lasers à fibres. Déjà kilowatt en continu, ils atteignent désormais les 1013 watts/cm2 avec des impulsions de la centaine de femtoseconde. Lors de cette présentation nous passerons en revue les potentialités des lasers à fibre. Nous décrirons les verrous technologiques qui ont été levés ces dix dernières années pour les régimes CW mais aussi femtosecondes. Nous montrerons également comment la prochaine génération de fibres optiques actuellement en développement permettra d'offrir des sources stables et de très haute puissance pour l'avenir proche.

  19. Orthographic Analogies and Early Reading: Explorations of Performance and Variation in Two Transfer Tasks.

    ERIC Educational Resources Information Center

    Savage, Robert; Stuart, Morag

    2001-01-01

    Investigates the use of orthographic analogies in 6-year-olds. Notes that neither rime nor phoneme awareness measures were correlated with rime inference uses and that vowel, but not rime inference, was correlated with scaffolding errors. Finds that rime detection was the strongest predictor of reading ability, whereas phoneme segmentation was the…

  20. Recombinative Generalization of Subword Units Using Matching to Sample

    ERIC Educational Resources Information Center

    Mahon, Catherine; Lyddy, Fiona; Barnes-Holmes, Dermot

    2010-01-01

    The purpose of the current study was to develop and test a computerized matching-to-sample (MTS) protocol to facilitate recombinative generalization of subword units (onsets and rimes) and recognition of novel onset-rime and onset-rime-rime words. In addition, we sought to isolate the key training components necessary for recombinative…

  1. Orthographic Analogies and Early Reading: Explorations of Performance and Variation in Two Transfer Tasks.

    ERIC Educational Resources Information Center

    Savage, Robert; Stuart, Morag

    2001-01-01

    Investigates the use of orthographic analogies in 6-year-olds. Notes that neither rime nor phoneme awareness measures were correlated with rime inference uses and that vowel, but not rime inference, was correlated with scaffolding errors. Finds that rime detection was the strongest predictor of reading ability, whereas phoneme segmentation was the…

  2. Analyse des transferts de chaleur et de masse transitoires dans un arena a l'aide de la methode zonale

    NASA Astrophysics Data System (ADS)

    Daoud, Ahmed

    Cette these presente les resultats d'une etude sur le mouvement de l'air et les transferts thermiques et massiques dans les arenas en regime transitoire et en 3D. Pour la partie aeraulique, il a ete question de developper un modele base sur la methode zonale qui permet de calculer les debits de l'air (dus a la ventilation et aux gradients de temperature) et de l'humidite entre les differentes zones du batiment et de determiner l'age de l'air dans chacune des zones. Pour la partie thermique, un modele de calcul du rayonnement entre les surfaces interieures du batiment qui a ete couple a TRNSYS afin de calculer sur une base annuelle les charges de chauffage et de refrigeration; ces dernieres tiennent compte des transferts radiatif et convectif, de la chaleur latente due a la condensation de l'humidite sur la glace et du surfacage. Le document presente est constitue de 7 chapitres qui peuvent etre resumes comme suit: Les chapitres 1, 2 et 3 sont consacres respectivement: a l'introduction generale, a la revue bibliographique et a la description du batiment modelise. Le chapitre 4 decrit l'approche developpee et la contribution importante qui y est apportee. Il presente l'utilisation de la methode zonale comme une alternative pratique aux methodes CFD car elle permet de realiser des simulations dynamiques sur une annee avec des temps de simulation tres courts et une precision acceptable. Il s'agit d'une approche intermediaire entre les modeles CFD et les modeles a un noeud d'air (considerant la temperature homogene dans un local). Le chapitre 5 est consacre a la methode de resolution numerique. L'outil de simulation a ete developpe en utilisant l'interface du logiciel TRNSYS: Le type 56 de ce logiciel a ete adopte comme modele energetique tandis que les autres modeles ont ete developpes et programmes en utilisant le logiciel MATLAB. Le chapitre 6 presente les resultats de simulation pour un arena sans faux plafond et avec un faux plafond et les resultats de mesures

  3. Contribution aux Methodes Analytiques des Substances a L'aide de Faisceaux de Particules Chargees

    NASA Astrophysics Data System (ADS)

    Saidi, Abdelmajid

    Nous avons vu les possibilites d'analyse par particules chargees des aerosols recueillis sur des filtres de type MILLIPORE. La meme technique a ete utilisee pour des filtres ayant servi a la filtration de l'eau du fleuve Saint-laurent. Deux techniques ont ete utilisees: (1) FAST (Forward Alpha Scattering Technique): pour analyser l'hydrogene, le carbone, l'oxygene et puis l'azote. Des alpha de 12 MeV ont ete utilises. (2) PIXE (Particle Induced X-ray Emission): pour analyser les elements moyens et lourds, dans ce cas des protons de 3 MeV ainsi que des ions d'argon de 1 et 1.6 MeV ont ete utilises. Les etudes ont montre que sous vide, la majorite des problemes proviennent des dommages causes par l'echauffement du a l'impact du faisceau sur le filtre. L'analyse quantitative par l'intermediaire du faisceau extrait peut presenter des difficultes en ce qui concerne les elements legers pour lesquels l'absorption des rayonnements caracteristiques dans l'atmosphere externe est importante. Les ions lourds se pretent mal aux analyses des aerosols du fait de leur limite de sensibilite. L'analyse directe de liquides par des protons est particulierement interessante puisqu'elle ne necessite aucune preparation prealable des echantillons. A cet effet, un programme de calcul de concentration des elements dans la solution a analyser a ete mis au point. Nous avons determine la limite de sensibilite de la methode PIXE pour les cibles minces (filtre) et pour le cas ou la matrice est de l'eau. Enfin, la technique FAST peut etre un complement de la technique PIXE.

  4. Factors Affecting the Reading of Rimes in Words and Nonwords in Beginning Readers with Cognitive Disabilities and Typically Developing Readers: Explorations in Similarity and Difference in Word Recognition Cue Use.

    ERIC Educational Resources Information Center

    Calhoon, J. Anne

    2001-01-01

    Comparison of the reading of rhymes by 20 children with cognitive disabilities (Down syndrome or autism) and 20 typically developing children (all matched for word recognition skills) found both groups were more similar than dissimilar in their rhyme-recognition accuracy, miscues, and grapheme-phoneme knowledge. (Contains references.) (Author/DB)

  5. [Requests for emergency appointments with dermatologists in private practice in France: the ETude Urgences en DErmatologie libérale (ET.U.DE) study].

    PubMed

    Penso-Assathiany, D; Bourdon-Lanoy, E; Derancourt, C; Roujeau, J-C; Bastuji-Garin, S

    2007-01-01

    Requests for emergency appointments are fairly common in private dermatologic practice in France. To our knowledge the frequency and reasons for such requests have not yet been evaluated. The primary objective of our study was to provide a quantitative and qualitative evaluation of such requests and to assess the underlying reasons. The secondary aim was to investigate for an association between emergency requests where response was justified within 48 hours and the symptoms reported by patients in order to establish a predictive score for the validity of requests. The study took place during one week in April 2004. Forty French dermatologists took part on a voluntary basis. They deliberately reduced their ongoing schedule to accommodate patients seeking an urgent appointment. We collected data regarding the normal professional activity of each dermatologist, reasons for appointments, symptoms, diagnosis and evaluation of the degree of emergency by the attending dermatologist. Univariate and multivariate analyses were performed and a score was attributed based on the results for the variables used in the logistic regression model. The mean number of patients seen at emergency appointments during the study week doubled in comparison with a normal period. During the week, 613 patients phoned and all questionnaires were completed for 538 (88%) patients. The most common reasons for requesting an appointment were: rash, eczema, pruritus, tumour modification, localized lesion and allergy. The most frequent diagnoses were: eczema, bacterial and viral infection, atopic dermatitis, mycosis and naevus. The dermatologists considered that the consultations were justified within 48 hours for one third of patients. In the multivariate analysis, factors significantly associated with a justified request were of a general medical rather than a dermatological nature: enlarged cysts, blisters, insomnia, impaired activity, onset or aggravation within the previous 7 days, inability to work. The score showed good specificity but poor sensitivity and discriminative value. These results suggest that requests for emergency appointments are more frequent than previously suspected (14% of all requests). Physicians considered that emergency appointments within 48 hours were justified for one third of patients. The reasons for consultation and the resulting diagnoses were similar to those seen in emergency hospital consultations. The criteria on which the need for emergency consultation was based were not for the most part dermatologic. The scoring system we established was not sensitive enough to allow reliable pre-selection of patients requiring emergency consultation by telephone.

  6. Etude du stockage de l'hydrogene sur des nanostructures de carbone microporeuses

    NASA Astrophysics Data System (ADS)

    Poirier, Eric

    2007-12-01

    Le stockage de l'hydrogene par adsorption sur des adsorbants nano-structures a ete etudie sous differentes conditions de pression et de temperature. Les adsorbants etudies sont principalement des nanotubes de carbone a simple paroi ainsi que des structures metallo-organiques. Les mesures ont ete realisees a l'aide de systemes gravimetriques et volumetriques tres sensibles specialement mis au point pour de petits echantillons necessitant un degazage in situ. Les appareils developpes, au nombre de quatre, comprennent deux systemes gravimetriques et deux systemes volumetriques. Ensemble, ces systemes couvrent la plage de pressions (0-100) bars ainsi que la plage de temperatures (77-295) K. Les differentes analyses montrent que l'adsorption d'hydrogene sur les adsorbants nano-structures etudies est maximale a 77 K et varie entre environ (1.5 et 4) % masse. A temperature ambiante, l'adsorption croit lineairement avec la pression et demeure sous les 1% masse pour des pressions inferieures a 100 bars. L'adsorption d'hydrogene sur ces materiaux dans ces conditions se compare notamment a celle obtenue sur des charbons actives. La modelisation de l'adsorption a egalement ete realisee dans des conditions cryogeniques a l'aide du modele de Dubinin-Astakhov sous une forme adaptee pour l'adsorption supercritique. Les enthalpies d'adsorption calculees a partir de ce modele varient sous les 6 kJ/mole et sont donc consistantes avec des processus de physisorption. L'applicabilite du modele de Dubinin-Astakhov suggere que l'adsorption d'hydrogene puisse etre representee par un processus de remplissage des pores par un pseudo-liquide. Ces travaux s'inscrivent dans un contexte ou la capacite d'adsorption reelle des nanostructures de carbone est sujette a la controverse. En consequence, l'approche experimentale adoptee se distingue par les differentes demarches mises de l'avant pour l'obtention de mesures fiables sur des echantillons de faibles masses ainsi que par son caractere comparatif. Ces demarches incluent le developpement, l'etalonnage et la contreverification de systemes de mesures volumetriques et gravimetriques sensibles au microgramme. Ces systemes sont de plus adaptes au degazage sous vide et a haute temperature des echantillons. La mise au point d'un systeme de controle de temperature sur un petit volume pour des mesures a hautes pressions et basses temperatures constitue egalement un aspect original de ces travaux. De plus, d'un point de vue davantage theorique, cette these se caracterise par la modelisation de l'adsorption supercritique d'hydrogene sur differents materiaux et la derivation d'une expression pour l'enthalpie d'adsorption independante de la temperature a l'aide du modele de Dubinin-Astakhov.

  7. Methodes de calcul des forces aerodynamiques pour les etudes des interactions aeroservoelastiques

    NASA Astrophysics Data System (ADS)

    Biskri, Djallel Eddine

    L'aeroservoelasticite est un domaine ou interagissent la structure flexible d'un avion, l'aerodynamique et la commande de vol. De son cote, la commande du vol considere l'avion comme une structure rigide et etudie l'influence du systeme de commande sur la dynamique de vol. Dans cette these, nous avons code trois nouvelles methodes d'approximation de forces aerodynamiques: Moindres carres corriges, Etat minimal corrige et Etats combines. Dans les deux premieres methodes, les erreurs d'approximation entre les forces aerodynamiques approximees par les methodes classiques et celles obtenues par les nouvelles methodes ont les memes formes analytiques que celles des forces aerodynamiques calculees par LS ou MS. Quant a la troisieme methode, celle-ci combine les formulations des forces approximees avec les methodes standards LS et MS. Les vitesses et frequences de battement et les temps d'executions calcules par les nouvelles methodes versus ceux calcules par les methodes classiques ont ete analyses.

  8. KIR haplotypes defined by segregation analysis in 59 Centre d'Etude Polymorphisme Humain (CEPH) families.

    PubMed

    Martin, M P; Single, R M; Wilson, M J; Trowsdale, J; Carrington, M

    2008-12-01

    The killer cell immunoglobulin-like receptor (KIR) gene cluster exhibits extensive allelic and haplotypic diversity. Variation at the locus is associated with an increasing number of human diseases, reminiscent of the HLA loci. Characterization of diversity at the KIR locus has progressed over the past several years, particularly since the sequence of entire KIR haplotypes have become available. To determine the extent of KIR haplotypic variability among individuals of northern European descent, we genotyped 59 CEPH families for presence/absence of all KIR genes and performed limited allelic subtyping at several KIR loci. A total of 20 unique haplotypes differing in gene content were identified, the most common of which was the previously defined A haplotype (f = 0.52). Several unusual haplotypes that probably arose as a consequence of unequal crossing over events were also identified. Linkage disequilibrium (LD) analysis indicated strong negative and positive LD between several pairs of genes, values that may be useful in determining haplotypic structure when family data are not available. These data provide a resource to aid in the interpretation of disease association data involving individuals of European descent.

  9. Environmental Indicators. A Preliminary Set = Indicateurs d'environnement. Une etude pilote.

    ERIC Educational Resources Information Center

    Organisation for Economic Cooperation and Development, Paris (France).

    This document provides a preliminary set of environmental indicators by which to measure environmental performance. The indicators are patterned on the outline of the Organisation for Economic Cooperation and Development (OECD) "Report on the State of the Environment," a companion volume published in the same year. This volume is…

  10. Littoral Infrared Ship Self Defence Technology Studies (Autodefense cotiere infrarouge des navires etudes technologiques)

    DTIC Science & Technology

    2014-05-01

    SET-088) Synthèse Ce groupe de travail a traité des aspects suivants de l’autodéfense côtière infrarouge : 1) La détection des missiles antinavires...recherche sur la propagation infrarouge a été un autre sujet d’intérêt pour le groupe de travail . Les activités principales de la recherche sur la...propagation IR ont concerné l’essai VAMPIRA avec le groupe de travail SET-056 (Intégration du Radar et de l’Autodéfense Infrarouge des Navires), l’analyse

  11. Fabrication et etude de cristaux photoniques pour les longueurs d'onde de telecommunication optique

    NASA Astrophysics Data System (ADS)

    Aboudihab, Ismail

    Nous avons fabrique et etudie des cristaux photoniques bidimensionnels et tridimensionnels. Les cristaux 3D sont constitues de microbilles de polystyrene autoassemblees. La structure inverse en BaTiO3 a ete aussi fabriquee, ou l'on remplace l'espace entre les microbilles par du BaTiO3, alors que les microbilles sont eliminees. Nous avons essaye en particulier de comprendre les differents phenomenes qui influencent la cristallisation de ces structures afin d'obtenir des films de meilleure qualite. Les cristaux bidimensionnels, constitues de cylindres vides imbibes dans un semiconducteur (As2S3 ou Si), sont obtenus par holographie laser. Nous avons montre que cette technique est tres interessante pour la production en serie de ces structures. Des guides d'ondes, des coupleurs, et des jonctions Y, imbibes dans des cristaux photoniques bidimensionnels, ont aussi ete fabriques. Des mesures optiques et des simulations numeriques ont ete menees dans le but de caracteriser ces structures.

  12. Etude de la stabilite d'un avion BWB (Blended Wing Body) de 200 passagers

    NASA Astrophysics Data System (ADS)

    Legros, Clement

    The Blended Wing Body (BWB) is a type of innovative aircraft, based on the flying wing concept. This new type of airplane shows several advantages compared to the conventional airplanes : economy of fuel, reduction of the weight of the structure, reduction of the noise and less impact on the environment, increased payload capacity. However, this kind of aircraft has a lack of stability due to the absence of vertical tail. Several studies of stability were already realized on reduced size models of BWB, but there is no study on a 200 passengers BWB. That's why, the main objective of this present study is to integrate the engines and theirs pylons into the existing conceptual design of the BWB to analyze of their impact on its static and dynamic stability over the flight envelope. The conception of the BWB was realized with the platform of design CEASIOM. The airplane, the engines and theirs pylons were obtained in the geometrical module AcBuilder of CEASIOM. The various aerodynamic coefficients are calculated thanks to Tornado program. These coefficients allow realizing the calculations of stability, in particular with the longitudinal and lateral matrices of stability. Afterward, the BWB flight envelope is created based on aeronautical data of a similar airplane, the Airbus A320. From this flight envelope, we get back several thousand possible points of flight. The last step is to check the static and dynamic stability, using the longitudinal and lateral matrices of stability and the Flying Qualities Requirements, for every point of flight. To validate our study of stability, the already existing studies of stability of the Boeing 747 will be used and compared with our model.

  13. Etude des facteurs de risque du retard de croissance intra-utérin à Lubumbashi

    PubMed Central

    Moyambe, Jules Ngwe Thaba; Bernard, Pierre; Khang'Mate, Faustin; Nkoy, Albert Mwembo Tambwe A; Mukalenge, Faustin Chenge; Makanda, Daudet; Twite, Eugene; Ndudula, Arthur Munkana; Lubamba, Cham; Kadingi, Arnauld Kabulu; Kayomb, Mutach; Kayamba, Prosper Kalenga Muenze

    2013-01-01

    Introduction Dans notre milieu, il n'existe aucune politique de prévention du Retard de Croissance Intra-Utérin (RCIU) clairement défini. L'objectif de ce travail était d'identifier les facteurs de risque de RCIU afin de proposer une stratégie de lutte contre cette pathologie en agissant surtout sur des facteurs pouvant faire l'objet d'une action préventive. Méthodes Une étude cas-témoins a été menée dans 11 centres hospitaliers de Lubumbashi en République Démocratique du Congo, de Janvier 2010 à Juin 2011, dans le but d'identifier les facteurs de risque du retard de croissance intra-utérin (RCIU). Au total 420 gestantes (cas et témoins) avec grossesse monofoetale d'au moins 24 semaines d'aménorrhée ont été inclues dans l'étude. Les cas correspondaient aux gestantes dont le poids du fœtus était resté inférieur au 10 eme percentile des courbes de référence d'Alexander, après 2 échographies successives réalisées à intervalle de 4 semaines. Les témoins correspondaient aux gestantes dont le poids du fœtus était supérieur ou égal au 10 eme percentile de mêmes courbes. A chaque cas a été apparié un témoin de même parité porteur d'une grossesse de même âge. Résultats L'analyse univariée a identifié comme facteurs de risque: la taille maternelle. Conclusion L'amélioration du niveau socio-économique des populations, la lutte contre le paludisme et les consultations prénatales mieux organisées couplées à une meilleure éducation sanitaire et nutritionnelle peuvent contribuer sensiblement à la réduction de la fréquence du RCIU à Lubumbashi. PMID:23504392

  14. Etude morphologique des poudres. Applications au titanate de baryum et à l'alumine

    NASA Astrophysics Data System (ADS)

    Prod'Homme, M.; Chermant, L.; Coster, M.; Chermant, J. L.

    1991-05-01

    In this paper, we specially looked to the study of shape of particles and aggregates of BaTiO3 and AI2O3 powders with very different physico-chemical features in order to characterize morphologically pulverulent media. Although the analysis of the shape may be carried out on two different scales, providing access either to the silhouette or to the roughness of particles or aggregates, only the investigation of the silhouette has been approached as a first step. For that purpose a number of shape factors was selected and correlations were looked for by statistical analysis. Dans cet article, nous nous sommes penchés plus particulièrement sur l'étude de la forme de particules et d'agrégats de poudres BaTiO3 et AI2O3, présentant des caractéristiques physico-chimiques très différentes, dans le but de caractériser morphologiquement des milieux pulvérulents. Bien que l'analyse de la forme puisse s'effectuer à deux échelles différentes permettant d'accéder, soit à la silhouette, soit à la rugosité des particules ou des agrégats, nous n'avons abordé ici, dans un premier temps, que l'étude de la silhouette. Nous avons pour cela sélectionné un certain nombre d'indices de forme et recherché des corrélations par analyse statistique.

  15. Etude Bacteriologique sur 30 Mois dans un Service de Brulés

    PubMed Central

    Chaibdraa, A.; Bentakouk, M.C.

    2008-01-01

    Summary Le pronostic des brûlures est souvent tributaire de complications infectieuses. Les objectifs de cette étude préliminaire rétrospective sont une évaluation de la flore microbienne et ses fluctuations selon la durée d'hospitalisation chez les patients du Centre des brûlés adultes de Annaba (Algérie). Ce travail porte sur 633 prélèvements microbiologiques positifs obtenus entre juin 2003 (inauguration du service) et décembre 2005. Selon le site de prélèvement la répartition est: cutané (78%), hémoculture (9%), prélèvement trachéo-bronchique (4%), uroculture (3%), sonde urinaire (3%), cathéter(3%). Les germes isolés sont: les staphylocoques (58%), les Pseudomonas (20%), le Candida albicans (5%), l'Acinetobacter (3%) et les autres germes (14%). Parmi les staphylocoques et les Pseudomonas recensés, respectivement 19% et 11% sont isolés la première semaine, contre 43% et 52% au-delà de 21 jours. Ces résultats confrontés aux données de la littérature confirment la prédominance du staphylocoque et du Pseudomonas. Le risque de contamination à partir des techniques invasives de réanimation est commun à toutes les équipes. La prolifération bactérienne est en relation avec la durée d'hospitalisation. Ces constatations doivent nous inciter à tirer bénéfice de l'expérience des autres services, en particulier sur les moyens, accessibles, de prévention de l'infection nosocomiale. PMID:21991102

  16. Etude d'un concept de coeur hybride refroidi a l'eau supercritique

    NASA Astrophysics Data System (ADS)

    Delattre, Baptiste

    Facing the current weather and energy global problem, Canada chose to develop a reactor cooled by water at supercritical conditions (SCWR). Inspired by the current CANDU-6 pressure tube technology, this concept should allow to save a substantial amount of efforts for developping a brand new kind of reactor by using the well-known pressure tube CANDU design. In fact, this type of reactor should be able to reach a better energy efficiency as well as other essential criteria about safety, security, non-proliferation... Nevertheless, there are still a lot of technology challenges to be dealt with to satisfy the differents obligations related to the use of supercritical water (SCW). Thus, materials to use remain undetermined because of a 25 MPa operating pressure and a 650.C temperature for the SCW coolant. Actually, materials in presence of SCW should be able to avoid too much corrosion and remain low neutrons absorbers. Additionnaly, the use of a light water coolant makes the neutronic absorption more important than in CANDU heavy-water cooled reactors. Additionally, a positive coolant void reactivity (CVR) and safety related problem remains among the challenges to overcome for developping a SCWR. Bringing about a solutions to all these problems remains very difficult and that's why some concessions on these criteria have to be made in order to achieve a viable reactor. This study presents some thougts and works in that direction. Originally developped in early studies about thermodynamic cycle optimization for a SCW power plant, a new hybrid reactor concept with two channels types has arise. To this purpose, we imagine a pressure tube core design but with two different types of channels: . Some channels have thermodynamic conditions where water goes through a supercritical state. . The other channels have "CANDU like" thermodynamic conditions allowing the flow of pressurized light water under sub-critical conditions. These two kinds of features should mitigate the drawbacks and constraints of a whole SCWR core while keeping some of the benefit of the SCW use (improved energy efficiency). The aim of this study is to determine whether or not this kind of hybrid core with two types of channels is viable. To this purpose we used neutronics as thermalhydraulic models. First of all, in this thesis, we describe the SCWR-development history and specific back- ground with bibliography commentaries and a global description of the hybrid reactor developped. Secondly, we provide a brief theorical review of the neutronics and thermalhydraulics concepts used in the DRAGON, DONJON and ARTHUR calculation codes. Afterwards we will be considering some cell and core models and their description. Among others, some coupled neutronics-thermalhydraulic calculations have been done. This is followed by a presentation of the results we obtained and a discussion of the viability of our reactor. Finallly, we conclude.

  17. Etude cristallochimique de LiPN 2: Une structure derivée de la cristobalite

    NASA Astrophysics Data System (ADS)

    Marchand, Roger; L'Haridon, Paul; Laurent, Yves

    1982-07-01

    LiPN 2 has been prepared by reaction between Li 3N and P 3N 5 nitrides. The unit cell is tetragonal with a = 4.567(1) and c = 7.140(4) Å. The space group is I overline42d . The structure is related to the β cristobalite type and is isostructural with CaGeN 2. It is built up from a PN 4 tetrahedra framework in the holes of which the lithium atoms are localized. The values of the rotation angle ф of tetrahedra, {c}/{a} ratio and θ (NPN) angle have been discussed in relation to the parameter x of the nitrogen atoms.

  18. Etude des interdiffusions en phase solide dans le contact Er/GaAs

    NASA Astrophysics Data System (ADS)

    Députier, S.; Guivarc'h, A.; Caulet, J.; Minier, M.; Guérin, R.

    1994-05-01

    Solid state interdiffusions between a thin film of erbium deposited under vacuum conditions and (001) and (111) GaAs substrates were investigated in the temperature range 350-800 ^{circ}C. Complementary analysis methods (RBS, X-ray diffraction) allow us to point out, according to annealing temperatures, successives steps of the interaction corresponding to different mixtures of phases, essentially binaries. These steps are strongly depending on the GaAs substrate orientation, especially the final step of the interdiffusions. On (001) GaAs, only two steps have been observed : no visible interaction is noticed between erbium and GaAs before 600 ^{circ}C ; the interaction begins at 600 ^{circ}C, evolves slightly and leads at 800 ^{circ}C to the nominal composition " Er{10}GaAs " which corresponds to a mixture of several phases Er5Ga3, Er and ErAs. On (111) GaAs, several steps of interaction have been found ; first of all, erbium reacts with the substrate at 400 ^{circ}C (Er5Ga3 + Er mixture), then the reaction is continuing at 600 ^{circ}C (Er5Ga3 + Er + ErAs mixture) before reaching at 800 ^{circ}C the nominal composition " Er{1,5}GaAs ", which is in fact a mixture of the three binaries ErAs + ErGa2 + Er3Ga5. It can be noticed that the 800 ^{circ}C annealing is not sufficient to reach the mixture of the phases ErAs + Ga which, according to the ternary phase diagram, should be the final stage of the interaction Er/GaAs. The analysis of the Er/GaAs interdiffusions shows that ErAs is the " key " compound around which the interaction progresses. This compound appears as an ideal candidate to realize epitaxial ErAs/GaAs heterostructures. Les interdiffusions en phase solide entre une couche mince d'erbium déposée dans des conditions d'ultra-vide et des substrats de GaAs orientés (001) et (111) ont été étudiées après des traitements thermiques d'une heure entre 350 et 800 ^{circ}C. L'utilisation de techniques complémentaires d'analyse (RBS, diffraction X) a permis de mettre en évidence, en fonction de la température de recuit, plusieurs étapes successives d'interaction correspondant à des mélanges de phases, essentiellement des binaires. Elles dépendent fortement de l'orientation du substrat de GaAs, en particulier l'étape finale des interactions. Sur GaAs (001), seules deux étapes ont été observées : avant 600 ^{circ}C, il n'y a pas d'interaction visible de l'erbium avec le substrat ; celle-ci ne s'amorce qu'à 600 ^{circ}C pour n'évoluer ensuite que faiblement et conduire, à 800 ^{circ}C, à une composition nominale " Er{10}GaAs ", mélange des phases Er5Ga3 + Er + ErAs. Sur GaAs (111), plusieurs étapes d'interaction sont observées : l'erbium réagit avec le substrat dès 400 ^{circ}C (mélange des phases Er5Ga3 + Er), puis l'interaction se poursuit à 600 ^{circ}C (mélange Er5Ga3 + Er + ErAs) avant d'atteindre à 800 ^{circ}C la composition nominale " Er{1,5}GaAs ", constituée d'un mélange de grains des trois binaires ErAs + ErGa2 + Er3Ga5. Il faut noter que le recuit à 800 ^{circ}C n'est pas suffisant pour atteindre le mélange de phases Ga + ErAs qui, selon le diagramme ternaire, devrait être le stade ultime de l'interaction Er/GaAs. L'analyse des interdiffusions Er/GaAs montre que ErAs est le composé " clé " autour duquel pivote l'interaction Er/GaAs. Ce composé apparaît comme un candidat idéal pour la réalisation d'hétérostructures épitaxiées ErAs/GaAs.

  19. Etude des interdiffusions en phase solide dans le contact Ni/AlAs

    NASA Astrophysics Data System (ADS)

    Députier, S.; Guivarc'h, A.; Caulet, J.; Poudoulec, A.; Guenais, B.; Minier, M.; Guérin, R.

    1995-04-01

    Solid-state interdiffusions between a thin film of nickel deposited under vacuum conditions and a thick layer of epitaxial AlAs on GaAs (001) and (111) substrates were investigated in the temperature range 200-600 ^{circ}C. Complementary analytical methods (RBS, X-ray diffraction, TEM) allow us to point out, according to annealing temperatures, successives steps of the interaction. These steps correspond either to ternary phases which were evidenced by the experimental determination of the Ni-Al-As phase diagram and labelled as A, B and D phases by comparison with the isostructural ternary phases in the Ni-Ga-As diagram or to mixture of ternaries and binaries, more or less strongly textured on the substrate. In fact, the nature of the observed phases is strongly depending on the AlAs substrate orientation, the kinetic of the reaction occurring being slower on AlAs(111) than on AlAs(001). On AlAs(001), a ternary B-phase + NiAl mixture is firstly observed, followed by a second mixture constituted of the ternary A-phase + NiAl and NiAs binaries, and finally, at the end of the interaction, the two binaries NiAl + NiAs appear. On AlAs(111), only two steps of interaction have been found; first of all, the ternary D-phase is obtained, before leading, at the end of the interaction, to the ternary B-phase + NiAl + NiAs mixture. In that case, the 600 ^{circ}C annealing is not sufficient to reach the mixture of the binaries NiAl + NiAs which, according to the ternary phase diagram, is the final stage of the Ni/AlAs interaction. The comparative study of the Ni/AlAs and Ni/GaAs interdiffusions shows that the binary NiAl is the “key” compound around which the Ni/AlAs interaction progresses when NiAs is the one of the Ni/GaAs interaction. The binary NiAl which is thermally stable and strongly textured on AlAs appears as an interesting candidate to prepare epitaxial NiAl/AlAs/GaAs heterostructures. Les interdiffusions en phase solide entre une couche mince de nickel déposée dans des conditions d'ultra-vide et des couches épaisses d'AlAs épitaxiées sur des substrats de GaAs orientés (001) et (111) ont été étudiées après des traitements thermiques d'une heure, sous balayage de gaz neutres, entre 200 et 600 ^{circ}C. L'utilisation de techniques complémentaires d'analyse (RBS, diffraction X, MET) a permis de mettre en évidence, en fonction de la température de recuit, plusieurs étapes successives d'interaction. Ces étapes correspondent soit à des phases ternaires, mises en évidence lors de la détermination expérimentale du diagramme Ni-Al-As et notées A, B, D par analogie avec celles du diagramme Ni-Ga-As, soit à des mélanges de phases constituées de binaires et/ou de ternaires, toutes ces phases étant plus ou moins fortement texturées sur le substrat. En fait, la nature des phases en présence dépend de l'orientation du substrat, la cinétique de réaction apparaissant plus lente pour l'interaction Ni/AlAs(111) que pour celle Ni/AlAs(001), les étapes successives sont observées : tout d'abord un mélange constitué de la phase ternaire B + NiAl puis un autre mélange : phase ternaire A + NiAl + NiAs et en fin d'interaction les deux binaires : NiAl + NiAs. Sur AlAs(111), seules deux étapes sont mises en évidence, la première correspond à la phase ternaire D, la seconde, en fin d'interaction, est constituée du mélange : phase B + NiAl + NiAs. On remarque dans ce cas le recuit à 600 ^{circ}C n'est pas suffisant pour atteindre le mélange des binaires NiAl et NiAs qui, selon le diagramme ternaire, est le stade ultime de l'interaction Ni/AlAs. L'analyse comparée des interdiffusions Ni/AlAs et Ni/GaAs montre que NiAl est le composé “clé” autour duquel pivote l'interaction Ni/AlAs alors que ce rôle était joué par NiAs lors des interdiffusions Ni/GaAs. Thermiquement stable et fortement texturé sur AlAs, le binaire NiAl apparaît comme un candidat prometteur pour la réalisation d'hétérostructures NiAl/AlAs/GaAs.

  20. Etude du comportement hydrogeologique de couvertures avec effet de barriere capillaire faites entierement de materiaux miniers

    NASA Astrophysics Data System (ADS)

    Kalonji, Alex Kabambi

    The acid mining drainage (AMD) generating mine sites must be restored to limit their long-term contamination of the environment. At the end of mining operations, covers with capillary barrier effects (CCBE), generally made of natural materials soils, are used as an oxygen barrier to isolate the tailings that generate acid mining drainage (AMD) from their immediate environment. Due to economic and social acceptability contraints and to the environmental impact of stripping (footprint) of natural soil pits, mining companies are increasingly interested in using non-acid generating waste rock as a substitute for natural soils as base materials to form capillary break layers in covers. The overall objective of this study was to evaluate the hydrogeological behaviour of CCBE made entirely of mining materials (desulphurized tailings from a desulphurization process and non-acid generating waste rock). The specific objectives of this project were : 1) to characterize the hydrogeological properties of waste rock (with truncated size) and desulphurized tailings; 2) to evaluate in laboratory instrumented columns the effectiveness of CCBE made entirely of mining materials; 3) to simulate the column tests using a 1D numerical code to model the fluid (water and gas) flow in the unsaturated media; and 4) to validate with 2D numerical modeling the ability to restore LaRonde tailings impoundment (Agnico Eagle Mines Limited) using a CCBE made of low-sulfide tailings and non-acid generating waste rock. To achieve the objectives, samples of waste rock were collected from Bousquet waste rock pile and tailings from the ore concentration plant before being pumped to the tailings impoundment. Desulphurized tailings with less than 2% S were produced in order to construct a non-reactive CCBE. After the physical, chemical, mineralogical and hydrogeotechnical characterization of cover materials, laboratory physical models of CCBC in instrumented columns were performed. Three configurations were tested. The first two columns had a different waste rock grain size (0-20 mm and 0-50 mm) in their lower coarse layers, and the tailings were introduced at a high solid percent, approximatively 74% (simulating mechanical deposition). The third column also had waste rock with particle size 0-50 mm in its bottom coarse layer, but with tailings placed a lower solid percent, approximatively 55% (simulating hydraulic deposition). The particle size of the coarse waste rock in the top layers was set at 0-50 mm for all three columns. Several cycles of wetting drainage in the three columns were performed. The results of these laboratory investigations in terms of volumetric water content and suction profiles confirm the potential of non-acid generating waste rock to be used in the capillary break layers of CCBE. To assess the long-term performance, several scenarios of numerical modeling were performed using Vadose/W 2007 numerical codes, by Geoslope int. A variation of the depth of the water table and natural and extreme climatic conditions were considered in this parametric study. The results of these predictions confirmed the long-term effectiveness of covers with mine waste rock in capillary break layers. The effectiveness was evaluated in terms of oxygen flux at the interface between the moisture-retaining layer (MRL) and the bottom capillary break layer. Under natural and extreme climatic conditions (two months without infiltration), and a variation of the depth of the water table level from 2 to 6 m, cumulative oxygen flux over a one year period varied between 10.6 and 97.5 g/m 2/year. For extreme climatic conditions, and for the same variation of the depth of the water table, the oxygen flux varied between 14.3 and 117.9 g/m2/year. The highest oxygen flux (117 g/m2/year) was obtained for a water table depth of 6 m under extreme climatic conditions. The influence of the particle size contrast between the water retention layer and the bottom capillary break layer on the oxygen flux was further highlighted using relatively fine and coarse sand in the coarse bottom layer. The numerical modeling results obtained with the coarse sand were almost similar to those obtained with waste rock. In the absence of the strong contrast (when the relatively fine sand was used), the water retention layer was drained and the oxygen flux which reached at the bottom of this layer increased considerably. The water table depth, the grain size, and the hydraulic contrast between the MRL and the bottom capillary break layer (CBL) proved to be the key parameters of the simulated model. In field conditions, CCBE are often inclined, and that this inclination can affect the performance of the cover to control the migration of oxygen. 2D modeling was also performed. The numerical model was built to represent approximatively the case of one of the dams of LaRonde tailings impoundment. Preliminary results show that CCBE made entirely of mining materials are effective even when placed over slopes. The degree of saturation of the two slopes in the numerical model was higher than 85%. The influence of the slope has not significantly affected yet the performance of the cover for the model studied in this thesis. The cumulative oxygen flux over one year at the bottom of the MRL (for horizontal distance of 182 m of the numerical model) are 4031.3g (22.1 g/m2/year) and 4617.7g (25.3 g/m2/year) for natural and extreme climatic conditions respectively. This study confirms that waste rocks have good potential to be used as capillary break materials in the configuration of such CCBE. Thereby, it is suggested that the option of using only mining materials be included in the analysis of the optimal mode of mine reclamation. This project also suggests that good management of the tailings and waste rock produced during mining operations will provide the materials which could then be used to restore the site. More research is recommended to further investigate this reclamation option through field experimental cells. If further research validates the laboratory results at the intermediate scale, the use of mining materials would be considered as an effective option for CCBE used to control post-closure pollution. This scenario could reduce the construction costs while promoting the social acceptability of mining projects by reducing the use of natural soils.

  1. Etude des defauts apparaissant dans les amenagements interieurs des avions d'affaires

    NASA Astrophysics Data System (ADS)

    Charette, Emilie

    The evolution of the aeronautic industry led to the development of new materials for these high performance applications. Among other examples, composite sandwich structures are increasingly used for interior body panels of business airplanes. These structures are assembled and fixed to the fuselage using metallic inserts bonded inside the sandwich panels with an epoxy resin adhesive. A thin film of wood veneer covers the visible side of interior furniture in order to bring sophistication and esthetic to the interior design. However, due to multiple factors, surface defects frequently appear on the veneered side of the panel where inserts are located. Moreover the defects tend to appear months after the airplane delivery causing costly reparations. The sources of defects can be mechanical ( deformation due to an excessive tightening), chemical (shrinkage of the epoxy adhesive) or the result of hygrothermal exposition. It is therefore important to understand the source of such surface defects and ultimately prevent or control their appearance. The present thesis deals with defects from chemical and hygrothermal sources appearing on the composite panels used on the interior body of business jets after aging. The main objective was to identify and quantify phenomena causing the defects on the interior panels of business planes. This research project is the first part of a project sponsored by CRIAQ and NSERC. The interaction of several materials can lead to various phenomena causing the apparition of surface defects. The project was thus divided into three parts in order to study an increasingly complex problem. the first study deals with the characterization of the different constitutive materials taken separately. This first part focused on thermal, rheological and mechanical aspects of epoxy adhesives. It was shown that the two adhesives used have different mechanical properties and cure kinetic reactions. In addition, the mechanical properties of sandwich composites panels were studied. The second study focused on the analysis of hygrothermal influence on the adhesive and the composite sandwich panels taken separately. Humidity and temperature can have an important effect on the constitutive materials, it is therefore important to know their influence. Finally, the third part deals with the influence of hygrothermal aging on a structure combining all the different materials. Sample panels including fixing zones (insert and resin) were made at the industrial partner's facility according to the industrial procedure. Subsequently, the samples have undergone an accelerated aging. By using deflectometry system, changes in local curvatures with respect to the aging conditions were observed. A correlation between the material characterization results, the aging effects and the surface defect gravity was performed to evaluate the sources and the occurrence of defects. Recommendations have also been made to ensure the project continuity. This project, carried out in an industrial context with the collaboration of Centre de Recherche Industrielle du Quebec ( CRIQ), 3M Canada and the Chaire de recherche sur les composites hautes performances (CCHP) of the department of mechanical engineering of Ecole Polytechnique de Montreal, highlights the importance of the choice of methods and materials in the manufacturing of composite structures.

  2. Le Francais parle. Etudes sociolinguistiques (Spoken French. Sociolinguistic Studies). Current Inquiry into Languages and Linguistics 30.

    ERIC Educational Resources Information Center

    Thibault, Pierrette

    This volume contains twelve articles dealing with the French language as spoken in Quebec. The following topics are addressed: (1) language change and variation; (2) coordinating expressions in the French spoken in Montreal; (3) expressive language as source of language change; (4) the role of correction in conversation; (5) social change and…

  3. Etude de l'effet du gonflement par les solvants sur les proprietes du caoutchouc butyle

    NASA Astrophysics Data System (ADS)

    Nohile, Cedrick

    Polymers and in particular elastomers are widely used for personal protective equipment against chemical and biological hazards. Among them, butyl rubber is one of the most effective elastomers against chemicals. However, if this rubber has a very good resistance to a wide range of them, it is sensitive to non polar solvents. These solvents will easily swell the material and may dramatically affect its properties. This situation may involve a large risk for. butyl rubber protective equipment users. It is thus essential to improve the understanding of the effect of solvents on the properties of butyl rubber. The research that was carried out had two objectives: to identify the parameters controlling the resistance of butyl rubber to solvents and to study the effect of swelling on the properties of butyl rubber. The results show that the resistance of butyl rubber to solvents appears to be controlled by three main parameters: the chemical class of the solvent, its saturation vapor pressure and its molar volume. In addition, swelling affects butyl rubber mechanical properties in a permanent way. The effects can be attributed to the extraction of plasticizers by the solvent and to the degradation of the physico-chemical structure of the polymer network. This chemical degradation was linked to a phenomenon of differential swelling which seems to be controlled by the solvent flow inside the material. These results question some general beliefs within the field of protection against chemical risks. They also open new perspectives for the development of predictive tools relative to the behavior of butyl rubber in the presence of solvents

  4. Etude par spectrometrie raman de corticosteroides derives de la fluocortolone: trimethylacetate et caproate.

    PubMed

    Gamot, A P; Vergoten, G; Saudemon, M; Fleury, G

    1985-05-01

    Les spectres Raman de trois corticostéroïdes: fluocortolone base, triméthylacétate et caproate de fluocortolone (TMAF et CAF) ontétéenregistrésàl'état polycristallin entre 150 et 4000 cm(-1). Une attribution des raies observées est proposée. Elle a montréla complexitédu problème poséàsavoir la différenciation de trois composés de structure trés voisine. Cependant quelques intervalles de fréquences contenant des raies spécifiques sont susceptibles d'e^tre utilisés afin de permettre l'identification des composésétudiés. Il convient en premier lieu de distinguer tout particulièrement les raies situées entre 1500 et 1800 cm(-1). Dans l'intervalle 1580-1690 cm(-1) celles-ci sont intenses et spécifiques de la structure conjuguée Delta(1,4) 3-one des corticostéroi des ce qui permet de distinguer la classe de médicamentàlaquelle appartiennent les substancesétudiées. La zone de fréquence comprise entre 1690 et 1750 cm(-1) témoigne non seulement de la présence d'une fonction cétonique sur la chai^ne latérale mais aussi de l'existence d'une fonction ester suivant que l'on y trouve respectivement une ou deux raies (fluocortolone base 1701 cm(-1); TMAF 1728, 1745 cm(-1); CAF 1723, 1745 cm(-1). La fluocortolone base présenteà1635 cm(-1) une raie qui n'est pas retrouvée chez les dérivès estérifiés. En second lieu, nous retiendrons les zones spectrales représentatives des chai^nes latérales estŕrifiées fixées sur le carbone C(21): chai^ne triméthylacétate 340-360, 570-610, 750-810 cm(-1) (dans cette dernière région commune au caproate et au triméthylacétate la différenciation des deux composés se fait grâceàla raieà796 cm(-1) absente dans le spectre du caproate); chai^ne caproate 1310-1350 cm(-1) (dans cet intervalle, le caproate présente un profil très particulier avec trois raies d'intensitévoisine). Cet ensemble de résultats doite^tre utilisépour identifier ces substances par spectroscopie Raman sur des quantitiés de l'ordre du picogramme provenant d'éluat d'HPLC.

  5. Machine learning etudes in astrophysics: selection functions for mock cluster catalogs

    SciTech Connect

    Hajian, Amir; Alvarez, Marcelo A.; Bond, J. Richard E-mail: malvarez@cita.utoronto.ca

    2015-01-01

    Making mock simulated catalogs is an important component of astrophysical data analysis. Selection criteria for observed astronomical objects are often too complicated to be derived from first principles. However the existence of an observed group of objects is a well-suited problem for machine learning classification. In this paper we use one-class classifiers to learn the properties of an observed catalog of clusters of galaxies from ROSAT and to pick clusters from mock simulations that resemble the observed ROSAT catalog. We show how this method can be used to study the cross-correlations of thermal Sunya'ev-Zeldovich signals with number density maps of X-ray selected cluster catalogs. The method reduces the bias due to hand-tuning the selection function and is readily scalable to large catalogs with a high-dimensional space of astrophysical features.

  6. PECVD de composes de silicium sur polymeres: Etude de la premiere phase du depot

    NASA Astrophysics Data System (ADS)

    Dennler, Gilles

    Since their first introduction in the early 90's, transparent barriers against oxygen and/or water vapor permeation through polymers, such as SiO 2, are the object of increasing interest in the food and pharmaceutical packaging industries, and more recently for the encapsulation of organic-based displays. It is now well known that these thin layers possess barrier properties only if they are thicker than a certain critical thickness, dc. For example, dc is around 12 nm in the case of SiO2 on KaptonRTM PI; below this value, the measured "Oxygen Transmission Rate" (OTR, in standard cm3/m2/day/bar) is roughly the same as that of the uncoated polymer. Until now, no detailed research has been carried out to explain this observation, but a hypothesis was proposed in the literature, based on island-like growth structure of the coating for d ≤ dc. According to this hypothesis, the surface energy of the polymeric substrates is so low that the Volmer-Weber (island-coalescence) growth mode occurs. We have aimed to verify this explanation, that is, to study the initial phase of silicon-compound (SiO2 and SiN) growth on four different polymeric substrates, namely polyimide (KaptonRTM PI), polycarbonate (LexanRTM PC), polypropylene (PP), and polyethyleneterephthalate (MylarRTM PET). Three different deposition methods were used, namely reactive evaporation of SiO, radio-frequency (RF) Plasma Enhanced Chemical Vapor Deposition (RF PECVD), and Distributed Electron Cyclotron Resonance (DECR) PECVD. In this latter case, the substrates were placed in three different positions: (i) in the active glow zone, (ii) downstream, and (iii) downstream, but shielded from photon emission (e.g. VUV) from the plasma. Angle-Resolved X-Ray Photoelectron Spectroscopy (ARXPS), Rutherford Backscattering Spectroscopy (RBS), and Scanning Electron Microscopy (SEM), the latter performed after Reactive Ion Etching (RIE) by oxygen plasma, revealed that growth indeed occurs in a Volmer-Weber mode in the case of evaporated films. The island coalescence was observed to occur at d = 1.2 nm, at which point the sticking coefficient of precursor species changes drastically. Finally, we have investigated the presence of an "interphase" between deposited coatings and the polymeric substrate. (Abstract shortened by UMI.)

  7. Etude linguistique du dialogue psychosomatique (A Linguistic Study of Psychosomatic Dialogue)

    ERIC Educational Resources Information Center

    Pouder, Marie-Christine

    1977-01-01

    A linguistic analysis of interviews between three patients and their psychiatrists and psychoanalysts which showed correspondence between the communication situation and the language used. The discussion includes reasons for choosing psychosomatic patients, lexical and syntactic analysis, and a short discussion of Harris's method of discourse…

  8. Etude de la formation de l'arc électrique dans le vide

    NASA Astrophysics Data System (ADS)

    Ravary, P.; Haug, R.

    1994-05-01

    From the measurements of voltage V and the current intensity i through a vacuum diode submitted to a fast rising voltage step, we deduce the time evolution of the ratio i/V^{3/2}. From the theoretical dependance of the ratio on the geometry and from the kinetics of anodic and cathodic plasmas, we compute the time evolution of the characteristic parameters of the discharge. La mesure du courant et de la tension aux bornes d'une diode à vide soumise à une haute tension impulsionnelle permet d'étudier l'évolution du rapport i (t)/V (t)^{3/2} de la diode. En introduisant la loi de variation de ce rapport en fonction de la géométrie et la cinématique des plasmas cathodique et anodique, on reconstitue l'évolution de différents paramètres de la décharge, en particulier l'accélération du front anodique, la perte de masse du matériau de l'anode, la variation de la température de la surface au centre de l'anode.

  9. Etudes de linguistique semitique et arabe (Studies of Semitic and Arabic Linguistics).

    ERIC Educational Resources Information Center

    Cohen, David

    Various aspects of Arabic and Semitic linguistics are discussed in this text. The nine chapters include: (1) fundamental Semitic vocabulary and the classification of southern dialects; (2) observations on nominal derivation by affixation in several Semitic languages; (3) an automatic analysis of literary Arabic; (4) "Addad" and…

  10. Etude par spectroscopie vibrationnelle des niobates de sodium et d'argent de structure perovskite

    NASA Astrophysics Data System (ADS)

    Husson, E.; Repelin, Y.

    Infrared and Raman spectra of the niobates NaNbO 3 and AgNbO 3 of perovskite structure are analysed. An assignment of the frequencies is proposed. The influence of the antiferroelectric direction upon the NbO bonds is shown, as the influence of the A cation upon the AO and NbO bonds.

  11. Etude des Excitons du Rutile Par Photoluminescence et Diffusion Raman Resonante

    NASA Astrophysics Data System (ADS)

    Amtout, Abdenour

    Le TiO_2 est classe parmi les semiconducteurs (isolants) ayant un gap direct interdit. Dans cette presente recherche, on s'est interesse aux transitions optiques proches de la region fondamentale de la bande interdite afin de confirmer la presence de resonances excitoniques et d'en determiner la nature exacte. En photoluminesence, nous avons observe six pics, notes A a F, situes respectivement a 3.031, 2.989, 2.977, 2.934, 2.839 et 2.737 eV. Le pic A est associe a l'exciton 2p_{xy},<=s pic B, C, et D aux repliques phononiques de symetrie Gamma _sp{5}{'} de l'exciton 1s quadrupolaire et les pics E et F aux repliques a deux et trois phonons du mode Gamma_sp {5}{'} d'energie 100 meV. En absorption, nous avons associe le pic situe a 3031 meV a l'exciton 2p_{xy}. En diffusion Raman resonante, nous avons vu que la contribution de l'exciton 2p_{xy } a la section efficace de diffusion est negligeable devant la partie non-resonante. Nous avons montre que le pic de diffusion hyper-Raman resonant correspond a l'exciton 2p_{xy}..

  12. Etude de l'isolation hybride en vue de son application dans les transformateurs de puissance

    NASA Astrophysics Data System (ADS)

    Kassi, Koutoua Simon

    For nearly a century the conventional insulation (oil / cellulose complex) was the type of insulation used in the power transformers and most electrical power equipments. But the cellulose paper, the solid part of this insulation has many weaknesses. Indeed, the aging of cellulose paper in power transformers is accelerated by moisture, oxygen, metal catalysts, temperature, etc.). The risk of failures is thereby increased. Another major weakness of cellulose paper is its inability to protect the electrical transformer windings against the harmful effects of corrosive sulfur. Given all the weaknesses of cellulose paper, several studies have been conducted to evaluate the performance of aramid paper, which has better thermal properties. The aramid paper is currently used as high temperature insulation, combined with high fire point oils (synthetic and vegetable oils), mainly in electric traction transformers. The hybrid solid insulation is associated with mineral oil or with high fire point oils; it finds application in transformers of fixed and mobile substations. Manufacturing technology is controlled by manufacturers but operators of electrical networks do not have baseline data (standards) as diagnostic tools, allowing them to monitor the health/condition of the isolation in this new type of transformer. The overall objective of this research was to study the hybrid insulation and to demonstrate its potential use in power transformers. This overall objective has been subdivided into three specific objectives, namely: (i) improving the diagnostic of the condition of solid hybrid insulation and conventional solid insulation; (ii) diagnosing the condition of oils sampled from hybrid, high temperature and conventional insulation and finally (iii) investigating the ability of aramid paper and cellulose paper to protect the copper (electrical windings) against harmful effects of corrosive sulfur. In order to achieve these objectives, thermal accelerated aging were conducted in laboratory : • according to ASTM D1934 (American Society for Testing and Materials), four different type of insulation samples were considered, namely the oil impregnated hybrid insulation, oil impregnated cellulose insulation, oil impregnated high temperature insulation and paperless oil samples. Following the aging procedure, a local overheating (thermal fault) was applied on the paper sample using an experimental setup designed in our laboratory (first and second specific objectives). • according to the IEC (International Electrotechnical Commission)-62535, for mineral, synthetic, vegetable and silicones oils (third specific objective). The degree of polymerization by viscosimetry and the determination of the carbon oxides by dissolved gas analysis (DGA) were determined to assess the condition of the paper in conventional insulation compared to that of the hybrid insulation. Our results indicate that cellulose paper in the hybrid insulation is less degraded when compared to the conventional insulation. Since the life of a transformer is directly related to the solid insulation, these results suggest that hybrid transformer insulation has a higher life than conventional ones. Subsequently, a very good correlation between amounts of oxides of carbon and degree of polymerization was established. This relationship might help improving the accuracy when interpreting the results of the DGA for transformers (first specific objective). Regarding the second specific objective, we used four physicochemical diagnosis techniques (dissolved decay products 'DDP', Turbidity, interfacial tension (IFT) and water content) to assess comparatively the quality of oils sampled from the four types of insulation. According to our results, the oil of the hybrid insulation indicated better quality at a certain stage of aging and especially after the application of thermal stress on the solid insulation. For the third specific objective, a qualitative study followed by a quantitative ones provided the following results: aramid paper better protects copper against corrosive sulfur in mineral oil; synthetic ester oils are not corrosive; the vegetable oil is not corrosive but in the presence of cellulose paper, a degree of corrosiveness is observed and the aramid paper promotes formation of corrosive sulfur in silicone oils. Based on the obtained results, the feasibility of using hybrid insulation in power transformers is possible. Keywords : power transformer; hybrid insulation; high temperature insulation; conventional insulation; sub-stations; aramid paper; cellulose paper; degree of polymerization; dissolved gases analysis (DGA); mineral oils; vegetable oils; synthetic oils; corrosive sulfur.

  13. Etude de la consolidation gravitaire en colonnes des remblais miniers cimentes en pate

    NASA Astrophysics Data System (ADS)

    El Aatar, Omar

    2011-12-01

    The challenge of underground mines backfilling in Abitibi region remains a major topic of investigation by many researchers in recent decades. For example, it has been observed in the backfilled stopes that the top of the fill settles systematically few days after its placement (by an average value varying between 0.9 and 1.5 m observed at Louvicourt mine). In addition, the strength of the cemented paste backfill (CPB) increases substantially, almost three times between the top and bottom of the backfilled stope. Some studies have also shown that the strength (unconfined compressive strength or UCS) of in situ CPB core specimens was 2 to 4 times of that of specimens of the equivalent lab-prepared CPB poured into plastic moulds. Among the many possible causes which could explain these observations, one can mention the self-weight consolidation of CPB. The main objective of this research is to understand the physical phenomena that govern the mechanical strength development within paste backfill after placement. To this end, three PVC columns, each of 3 m high, were manufactured and installed at the Louvicourt (LVT) mine and LaRonde (LRD) mine backfill plants to be in-filled. The column tests performed at the Louvicourt mine backfill plant allowed simulating different drainage configurations of a backfilled stope, namely, full drainage, partial drainage and no drainage while column tests performed at the LaRonde mine allowed comparing the response of three different paste backfill mix recipes for unique drainage condition: combined lateral and vertical drainage. Before the columns in-filling, the effect of mixing time on the slump height value of CPB was evaluated. Each column was then in-filled with CPB having a slump height similar to that of the fill used underground and in two sequences of in-filling of about 1.45 to 1.5 m over a time period of 24 hours. The monitoring of in-filled columns with CPB lasted for 5 days and consisted of measuring the amount of drainage water along with the observed settlement at the top surface of CPB column at time intervals of 1 hour. For the Louvicourt mine columns, several CPB core samples were extracted after 45 days curing time for experimental characterization of their mechanical, physical and hydro-geochemical properties. For the LaRonde mine columns, pore pressure and suction were measured using pressure sensors installed along the column height. The results obtained show that the maximum amount of drainage water (fully drained column) does not exceed 15% of the total water of the CPB, the maximum strength of CPB is reached with the fully drained column (2.9 MPa after 87 days of curing) and that the behavior of a backfilled stope at Louvicourt mine would be closer to either fully drained or partially drained column configurations. A clear distinction of the microstructure as a function of columns depth with the highest values of porosity and specific surface areas were observed in the case of drained CPB.

  14. Etudes de linguistique semitique et arabe (Studies of Semitic and Arabic Linguistics).

    ERIC Educational Resources Information Center

    Cohen, David

    Various aspects of Arabic and Semitic linguistics are discussed in this text. The nine chapters include: (1) fundamental Semitic vocabulary and the classification of southern dialects; (2) observations on nominal derivation by affixation in several Semitic languages; (3) an automatic analysis of literary Arabic; (4) "Addad" and…

  15. Vocational Guidance within the Context of the Democratization of Education. Rapports, etudes...S.129.

    ERIC Educational Resources Information Center

    Siebel, Anselm

    This paper, based on information concerning the current status of vocational guidance in various countries, describes the main trends in its development in the context of the democratization of education. The experiences of the following countries are reviewed: Austria, Czechoslovak Socialist Republic, Federal Republic of Germany, France, German…

  16. Pratique d'apprentissage en ligne aux etudes superieures (Online Learning for Higher Education).

    ERIC Educational Resources Information Center

    Marchand, Louise

    2001-01-01

    Online learning requires new approaches to teaching and learning. At the University of Montreal, 28 graduate students in education and adult students specializing in educational technology attended an experimental distance education course. Students identified advantages and disadvantages of online learning/teaching and reflected on how the course…

  17. Etude et simulation des groupes convertisseurs-machines synchrones a six phases

    NASA Astrophysics Data System (ADS)

    Doyon, Jean-Francois

    Since many years, multiphase (n > 3) machines represent a growing research interest in the electrical machines domain. This type of machine can be used for many systems like automotive electrical traction, electric ship propulsion, wind farms or high-power industrial applications. Above all multiphase machines, the six phases wounded rotor synchronous machine brings a huge interest. Subsequently, using that kind of machine in any application requires a good understanding of the machine model and its respective converters. Hence, simulation represents a great way to study the behaviour and design of such applications that uses six phases wounded rotor synchronous machines. The present research concerns the study and simulation of six phase synchronous machinesconverters systems. From this project resulted the implementation of the six phases wound rotor salient pole synchronous machine in the Demos library of Matlab SimPowerSytems. In terms of study, a six phase machine electric drive is designed as well as a six phase machine implementation in a type 4 wind farm. The modeling of the six phase synchronous machine is fully detailed for the electrical part and the mechanical part. Then, the voltage source inverter electric drive with hysteresis control is conceived. Simulations of torque control, speed control and degraded mode of the machine are executed. The results illustrate the electric drive efficiency. This is followed by the type 4 wind turbine application of the machine. The wind farm is connected to a 120 kV grid, where a voltage drop fault appears at the 120 kV bar for a duration of six 60 Hz cycles. The results show a good operation of the regulators during the fault. This application is also subjected to a degraded mode, where results illustrate once again a good system regulation. Also, for the electric drive and the wind farm applications, a comparative study is made for the use of an asymmetrical versus symmetrical winding configuration of the machine. It is shown that for these two configurations, the total harmonic distortion seen from the source are similar. Finally, detailed model and average model of the converters are made for the electric drive and the wind turbine. The results show great similarity between the models.

  18. Vocational Guidance within the Context of the Democratization of Education. Rapports, etudes...S.129.

    ERIC Educational Resources Information Center

    Siebel, Anselm

    This paper, based on information concerning the current status of vocational guidance in various countries, describes the main trends in its development in the context of the democratization of education. The experiences of the following countries are reviewed: Austria, Czechoslovak Socialist Republic, Federal Republic of Germany, France, German…

  19. Language Teaching with the Help of Multiple Methods. Collection d'"Etudes linguistiques," No. 21.

    ERIC Educational Resources Information Center

    Nivette, Jos, Ed.

    This book presents articles on language teaching media. Among the titles are: (1) "Il Foreign Language Teaching e l'impiego degli audio-visivi" (Foreign Language Teaching and the Use of Audio Visual Methods) by D'Agostino, (2) "Le role et la nature de l'image dans l'enseignement programme de l'anglais, langue seconde" (The Role and Nature of the…

  20. Environmental Indicators. A Preliminary Set = Indicateurs d'environnement. Une etude pilote.

    ERIC Educational Resources Information Center

    Organisation for Economic Cooperation and Development, Paris (France).

    This document provides a preliminary set of environmental indicators by which to measure environmental performance. The indicators are patterned on the outline of the Organisation for Economic Cooperation and Development (OECD) "Report on the State of the Environment," a companion volume published in the same year. This volume is…

  1. Etude morphométrique de l'oreille externe chez les jeunes adultes

    PubMed Central

    Nyemb, Philippe Manyacka Ma; Sankale, Anne-Aurore; Ndiaye, Lamine; NDiaye, Aïnina; Gaye, Magaye

    2014-01-01

    Introduction Connaitre les dimensions normales de l'oreille externe constitue un pré-requis en chirurgie. Le but de ce travail est de déterminer les valeurs moyennes des différentes mesures morphométriques des oreilles gauches et droites dans notre population d’étude. Méthodes Notre groupe d’étude était constitué de 100 sujets adultes jeunes (50 femmes et 50 hommes) âgés de 18 à 25 ans, et exempts de traumatismes ou d'anomalies congénitale de l'oreille externe. Les différentes mesures répertoriées étaient représentées par: la hauteur totale de l'oreille, la largeur totale de l'oreille, la hauteur lobulaire, la largeur lobulaire, la distance tragus - anti-hélix, la distance tragus - hélix, ainsi que la projection de l'oreille. Résultats L’âge moyen de notre population d’étude était de 22 ans. La hauteur totale de l'oreille était respectivement de 61,6 et 60,3 mm chez les sujets de sexe masculin et féminin. La largeur totale retrouvée était respectivement de 32,5 et 30,8 mm. Pour toutes les distances mesurées, nous retrouvions des différences entre hommes et femmes, ainsi que d'un coté à l'autre. Conclusion Pour le clinicien, il est important de prendre en compte les mesures morphométriques de l'oreille externe non seulement dans un but diagnostic, mais également pour reproduire lors de sa reconstruction une oreille anatomiquement correcte. PMID:25932068

  2. Etude par elements finis du comportement thermo-chimiomecanique de la pâte monolithique

    NASA Astrophysics Data System (ADS)

    Girard, Pierre-Luc

    Aluminum industry is in a fierce international competition requiring the constant improvement of the electrolysis cell effectiveness and longevity. The selection of the cell's materials components becomes an important factor to increase the cell's life. The ramming paste, used to seal the cathode lining, is compacted in the joints between the cathode and the side wall of the cell. It is a complex thermo-chemo-reactive material whose proprieties change with the evolution of his baking level. Therefore, the objective of this project is to propose a thermo-chemo-mechanical constitutive law for the ramming paste and implement it in the finite element software ANSYSRTM. A constitutive model was first chosen from the available literature on the subject. It is a pressure dependent model that uses hardening, softening and baking mechanisms in its definition to mimic the behavior of carbon-based materials. Subsequently, the numerical tool was validated using the finite element toolbox FESh++, which contains the most representative carbon-based thermochimio- mechanical material constitutive law at this time. Finally, a validation of the experimental setup BERTA (Banc d'essai de resistance thermomecanique ALCAN) was made in prevision of a larger scale experimental validation of the constitutive law in a near future. However, the analysis of the results shows that BERTA is not suited to adequately measure the mechanical deformation of such kind of material. Following this project, the numerical tool will be used in numerical simulation to introduce the various effects of the baking of the ramming paste during the cell startup. This new tool will help the industrial partner to enhance the understanding of Hall-Heroult cell start-up and optimize this critical step.

  3. Contribution a l'etude de l'inactivation de micro-organismes par plasma

    NASA Astrophysics Data System (ADS)

    Benhacene-Boudam, Mustafa-Karim

    The present work is a deepening of some specific research aspects concerning medical device sterilization by ionized gases, that were initiated almost ten years ago and pursued since then by the "Sterilization team" of the Groupe de physique des plasmas. Initially, the thesis was directed at spore inactivation by atmospheric-pressure plasmas with the intent of showing that it was possible to reach sterility mainly by the action of UV photons, therefore minimizing damage to materials (in contrast to using chemically reactive species from the plasma) and, at the same time, achieving a greater control of the process through its better understanding. We actually succeeded in demonstrating the possibility of spore inactivation based on the dominant action of UV photons issued from an atmospheric-pressure plasma. However, the low inactivation efficiency and the practical difficulty of the atmospheric-pressure plasma used made us turn to low-pressure post-discharge sterilization systems. To comply with this new goal, we first characterized, essentially through emission spectroscopy, the flowing afterglow of a N2-O2 low-pressure discharge, concentrating on the properties and effects of the early and late post-discharges as far as sterilization is concerned. We demonstrated that the early afterglow is responsible for heavy damage to processed polymers but that it is possible to reduce its influence provided a minimum percentage of O2 is added in the N2-O2 mixture and also by moving away the plasma source from the sterilization chamber entrance. We then studied the combined effects, on the kinetics of spore inactivation, of the species (UV photons, radicals) issued from the plasma and of the heating of the petri dish, using B. atrophaeus spores as reference microorganisms. We clearly proved the existence of synergy between UV photons and heating in inactivating spores, provided UV photons and heating act simultaneously. Whatever the O2% in the mixture, and thus the UV intensity, the inactivation rate was also found to obey a fluence law and its dependence on temperature could be modeled by the Arrhenius relation. Keywords: sterilization, atmospheric-pressure plasma, low-pressure plasma, UV photons, bacterial spores, survival curves, UV and heating synergy.

  4. Rocket Motor Plume Technology (L’Etude des Jets des Moteures-Fusees)

    DTIC Science & Technology

    1993-06-01

    being normally limits the choice of material cartridge loaded or case bonded, to filled rubbers . Because of the higher The advantages of cartridge load...achieve very low scattering cofficients heat resistant/erosion resistant sub micron particles should be used. The material 3uch as Butyl; EPDM or other...chief source of smoke in charge chlorosulphonated polyethylene inhibitor formulations is due to unburnt rubber . These are normally heavily hydrocarbons

  5. Etude histopathologique des adénopathies cervicales à Yaoundé, Cameroun

    PubMed Central

    Sando, Zacharie; Fouelifack, Florent Ymele; Fouogue, Jovanny Tsuala; Fouedjio, Jeanne Hortence; Ndeby, Yvette Sandrine Ngo; Djomou, Francois; Fewou, Amadou; Oyono, Jean-Louis Essame

    2014-01-01

    Introduction Les adénopathies cervicales ont été très peu étudiées au Cameroun. Méthodes Pour améliorer leur connaissance nous avons mené une étude rétrospective et descriptive dans les cinq principaux laboratoires de la capitale du pays en vue d'en déterminer les aspects histopathologiques. Résultats Nous avons colligé 292 cas. L’âge moyen était de 30,95 ±4,11ans et le ratio homme / femme était de 0,96/1. Les principaux diagnostics histologiques étaient les suivants: tuberculose ganglionnaire (39,38%), les lymphadénites (18,49%), les lymphomes malins non hodgkiniens (12,33%), la maladie de Kaposi ganglionnaire (5,82%), les métastases de carcinome (5,82%) et la maladie de Hodgkin (5,14%). Dans 95,65% des cas le diagnostic était posé au-delà du deuxième mois d’évolution des symptômes. Conclusion Nos résultats, quoique préliminaires, sont une contribution à l'amélioration de la stratégie diagnostique et thérapeutique dans nos hôpitaux aux ressources limitées. PMID:25848448

  6. Etude de films magnétiques de l'alliage Fe_{60}Al_{40}

    NASA Astrophysics Data System (ADS)

    Fnidiki, A.; Eymery, J. P.

    1991-06-01

    We show that the coevaporation technique like ion implantation, allows us to obtain Fe{60}Al{40} which is both chemically disordered and ferromagnetic at 293 K. However, differences between implanted bulk alloy and thin films of the same composition have been observed concerning the temperature evolution of magnetic properties. In the first case, magnetic effects disappear as soon as 400 K; in the second case, one still observes a significant ferromagnetic fraction at room temperature after annealing at 700 K and cooling down. Moreover, the hyperfine field at the 57 iron nucleus increases. This leads to the hypothesis of iron rich phases and hence indicates that the alloy does not reoder. On montre que la technique de coévaporation permet, comme l'implantation ionique, d'obtenir Fe{60}Al{40} désordonné au point de vue atomique et ferromagnétique à 293 K. Il s'avère cependant qu'il y a des différences entre l'alliage massif implanté et les films minces de même composition en ce qui concerne l'évolution en température des propriétés magnétiques. Dans le premier cas, il y a disparition des effets magnétiques dès 400 K ; dans le second, on observe encore une fraction ferromagnétique importante après chauffage et retour à l'ambiante. De plus, le champ hyperfin au noyau du fer 57 croît, ce qui conduit à l'hypothèse de zones enrichies en fer et, par suite, indique que l'alliage ne se réordonne pas.

  7. Etude methodologique de l'imagerie optique diffuse couplee a l'electroencephalographie

    NASA Astrophysics Data System (ADS)

    Chapuisat, Sarah

    Diffuse Optical Imaging (DOI) and electroencephalography (EEG) are two complementary functional brain imaging modalities: they do not image the same physiological phenomenon, but their spatial and temporal resolutions are of the same order of magnitude. Because the relationship between electrical (as measured by EEG) and hemodynamic (as measured by DOI) activities is still poorly understood, being able to record EEG and DOI data simultaneously appears necessary. On the experimental side, the aim of this project was to adapt an EEG cap to introduce optical fibers and thus, record DOI and EEG simultaneously. A study of the activations in the premotor and motor cortices, involved in movement preparation, allowed us to validate the acquisition setup, which nevertheless needs to be further improved. The theoretical part of this work focused on the use of regions reconstructed from DOI data as a spatial prior for the resolution of the inverse problem in EEG (i.e. the source location) via a Bayesian model. Simulation data gave us an accurate assessment of the contribution of DOI data and showed in particular that the use of a prior improved the amplitude of the reconstructed EEG sources. This study also showed that, regardless of the spatial coherence between DOI and EEG activities, the use of DOI prior did not worsen the EEG reconstruction. Although both the theoretical model and the acquisition system remain to be improved, this work showed the interest and feasibility of simultaneous EEG and DOI acquisition. Key words: diffuse optical imaging, near infrared spectroscopy, electroencephalography, movement preparation, Bayesian estimation

  8. Contributions a l'etude et a l'application industrielle de la machine asynchrone

    NASA Astrophysics Data System (ADS)

    Ouhrouche, Mohand-Ameziane

    The work presented in this thesis, done in the Electrical Drives Laboratory of Electrical and Computer Engineering Department, deals with the industrial applications of a three-phase induction machine (electrical drives and electricity generation). This thesis, characterized by its multidisciplinary content, has two major parts. The first one deals with the on-line and off-line parametric identification of the induction machine model necessary to achieve accurate vector control strategy. The second part, which is a resume of a research work sponsored by Hydro-Quebec, deals with the application of an induction machine in Asynchronous Non Utility Generators units (ANUG). As it is shown in the following, major scientific contributions are made in both two parts. In the first part of our research work, we propose a new speed sensorless vector control strategy for an induction machine, which is adaptive to the rotor resistance variations. The proposed control strategy is based on the Extended Kalman Filter approach and a decoupling controller which takes into account the rotor resistance variations. The consideration of coupled electrical and mechanical modes leads to a fifth order nonlinear model of the induction machine. The load torque is taken as a function of the rotor angular speed. The Extended Kalman Filter, based on the process's nonlinear (bilinear) model, estimate simultaneously the rotor resistance, angular speed and the flux vector from the startup to the steady state equilibrium point. The machine-converter-control system is implemented in MATLAB/SIMULINK environment and the obtained results confirm the robustness of the proposed scheme. As in the electrical drives erea, the induction machine is now widely used by small to medium power Non Utility Generator units (NUG) to produce electricity. In Quebec, these NUGs units are integrated into the Hydro-Quebec 25 kV distribution system via transformer which exhibit nonlinear characteristics. We have shown by using the ElectroMagnetic Program (EMTP) that, in some islanding scenarios, i.e. that the NUG unit is disconnected from the power grid, in addition to frequency variations, appearence of high an abnormal overvoltages, ferroresonance should occur. As a consequence, normal protective devices could fail to securely operate, which could cause serious damages to the equipment and the maintenance staff. This result, established for the first time , can be useful to improve the reliability of the NUGs units and is considered important by the power engineering community. This has led to a publication in the John Wiley & Sons Encyclopedia of Electrical and Electronics Engineering which will be available in February 1999 ( http://www.engr.wisc.edu/ ece/ece).

  9. Etude descriptive et analytique du cancer de l’œsophage au Togo

    PubMed Central

    Oumboma, Bouglouga; Mawuli, Lawson-Ananissoh Laté; Aklesso, Bagny; Laconi, Kaaga; Datouda, Redah

    2014-01-01

    Introduction Décrire les aspects épidémiologiques, cliniques, endoscopiques et histologiques du cancer de l’œsophage (CO) au Togo. Méthodes Il s'agit d'une étude rétrospective descriptive et analytique menée sur 8 ans (Janvier 2005-Décembre 2012) dans le service d'hépato-gastroentérologie (HGE) du CHU Campus de Lomé. Etaient inclus les dossiers des patients hospitalisés pour CO confirmé histologiquement. Résultats Sur 8 ans, 24 patients remplissant nos critères d'inclusion ont été retenus soit 3cas de CO par an et 0,55% des hospitalisations. L’âge moyen des patients était de 57,08 ans (extrêmes: 32 et 82 ans). La dysphagie et l’épigastralgie étaient les motifs d'hospitalisation les plus rencontrés. L'alcool (n=15), le tabac (n=13) étaient les facteurs de risque les plus présents. A la fibroscopie, les lésions étaient ulcéro-bourgeonnantes et hémorragiques (n=12), ulcéro-bourgeonnantes (n=5); ces lésions siégeaient au niveau du 1/3 inférieur (n= 11), à l'union 1/3 supérieur 1/3moyen de l’œsophage (n= 13) et aucun au niveau du 1/3 supérieur. Seize lésions étaient des carcinomes épidermoïdes et 3 des adénocarcinomes. L’évolution dans le service a été fatale dans 2cas; 16 patients avaient été transférés en chirurgie pour des soins palliatifs et 5 patients (20,8%) étaient perdus de vue. Conclusion Le CO semble en augmentation au Togo. L'alcool et le tabac sont les facteurs de risque et le pronostic sévère dans notre série est lié au retard diagnostic. Son dépistage précoce passe par une consultation rapide devant toute dysphagie chez un sujet de 50 ans et plus. PMID:25883742

  10. L'etude de l'anglais non standard. (The Study of Nonstandard English)

    ERIC Educational Resources Information Center

    Labov, William

    1974-01-01

    Examines current sociolinguistic theories concerning nonstandard English in an effort to help teachers of standard English to understand the problems facing their students and to apply their new knowledge in the classroom. (PM)

  11. Structure electronique de nanorubans de graphene avec des contacts metalliques: Une etude ab initio

    NASA Astrophysics Data System (ADS)

    Archambault, Chloe

    Graphene, a graphite monolayer presenting novel exciting properties, has attracted much attention recently in the scientific community as well as in the high-technology industry. In electronics, nanoribbons -- narrow strips of graphene which happen to be semiconducting-- could possibly allow further miniaturization of electronic devices such as transistors because of their atomic thickness. On the other hand, once making devices, the problem of metallic contacts, which can have critical impact at the nanoscopic scale, cannot be evaded. For example, metal induced gap states may short-circuit very short devices. With this in mind, the interaction of gold, palladium and titanium contacts with finite size graphene nanoribbons has been studied using ab initio density functional theory calculations. This theoretical approach made it possible to study separately and then conjugate four important aspects of the metal-ribbon interaction: bonding, charge transfer, electrostatics and metal induced gap states. Another goal of this project was to study size effects related to the ribbons' dimensions and to estimate the minimal channel length necessary for a device to operate as expected without the unwanted effect of induced gap states. Aside from the high precision achieved, these calculations stand out from earlier studies because they take into account finite size effects which often prevail in small ribbons. Using this model for the metal-nanoribbon junction, it was shown that, as for two-dimensional graphene, the bonding between a ribbon and a metal can be of two types depending on the electronic configuration of the metal. In the first case, physisorption, weak bonding resulting in a large separation distance between ribbon and electrode, is illustrated by the gold contact. On the other hand, titanium, because of its high density of states at the Fermi level, binds more strongly with graphene nanoribbons. This chemisorption is characterized by strong hybridization between the metal and the ribbon's orbitals. This leads to the apparition of intense evanescent gap states in the ribbon. As for palladium, it represents an intermediate case showing some but not as much hybridization. For all three metals, right under the contact, we observe a net decrease of electron density in the ribbon in favour of the contact. Effectively, any kind of bonding is generally associated with charge transfer necessary to balance the work function difference. As expected, a metal with a large work function such as gold and palladium tends to attract electrons. However, this behaviour is surprising from titane whose work function is much smaller. This can only be explained by considering the large hybridization of the ribbon's orbitals. Moreover, the charge transfer is not restricted to the area under the contact as an evanescent charge can also be observed in the channel. This charge results from the occupation of metal induced gap states and its sign depends on the position of the charge neutrality point. The calculations presented don't take into account the effect of temperature. Nevertheless, the position of the Fermi level relative to the ribbon's bands suggests that at non-zero temperature, gold and palladium would p dope the graphene nanoribbons while titanium would have the opposite effect. The charge redistribution in the junction generates a molecular-sized dipole which is responsible for the slowly varying three-dimensional potential profile, a particularity of low dimensional systems. A potential barrier thus appears at the interface and controls band curvature in the device, but it can also constitute an obstacle to efficient charge injection. The intimate relation between the titanium contact and the ribbons seems to maximize screening and reduce considerably the height of the barrier, which could turn out to be beneficial. Finally, metal induced gap states slowly decaying in the channel have been observed directly in graphene nanoribbons for the first time. Their characteristic evanescent shape is clearly distinguishable. The extent of the gap states was measured to be on the order of a nanometer. It depends mostly on the ribbon's bandgap which varies both with its length and width. The bandgap, which can easily be measured experimentally, could thus be a useful tool to predict the penetration of gap states, a must-have information in order to limit the undesired effect of gap states since it sets for a device the minimal channel length (˜1-2 nm). In summary, these theoretical results could be used as a guideline in the conception of electronic devices made of graphene nanoribbons in which doping and potential profile need to be optimized while making sure that metal induced gap states do not compromise normal operation.

  12. Etude des performances de solveurs deterministes sur un coeur rapide a caloporteur sodium

    NASA Astrophysics Data System (ADS)

    Bay, Charlotte

    The reactors of next generation, in particular SFR model, represent a true challenge for current codes and solvers, used mainly for thermic cores. There is no guarantee that their competences could be straight adapted to fast neutron spectrum, or to major design differences. Thus it is necessary to assess the validity of solvers and their potential shortfall in the case of fast neutron reactors. As part of an internship with CEA (France), and at the instigation of EPM Nuclear Institute, this study concerns the following codes : DRAGON/DONJON, ERANOS, PARIS and APOLLO3. The precision assessment has been performed using Monte Carlo code TRIPOLI4. Only core calculation was of interest, namely numerical methods competences in precision and rapidity. Lattice code was not part of the study, that is to say nuclear data, self-shielding, or isotopic compositions. Nor was tackled burnup or time evolution effects. The study consists in two main steps : first evaluating the sensitivity of each solver to calculation parameters, and obtain its optimal calculation set ; then compare their competences in terms of precision and rapidity, by collecting usual quantities (effective multiplication factor, reaction rates map), but also more specific quantities which are crucial to the SFR design, namely control rod worth and sodium void effect. The calculation time is also a key factor. Whatever conclusion or recommendation that could be drawn from this study, they must first of all be applied within similar frameworks, that is to say small fast neutron cores with hexagonal geometry. Eventual adjustments for big cores will have to be demonstrated in developments of this study.

  13. Etude des proprietes microstructurales et rheologiques de suspensions non-aqueuses d'argile

    NASA Astrophysics Data System (ADS)

    Mobuchon, Christophe

    Phyllosilicates or layered silicates consist of individual layers with nanometric dimensions. In static fluids without external forces, attractive and repulsive colloidal forces acting between the colloidal layers lead to their self-organization on multiple length scales. Under flow, a wide range of complex rheological behaviors, including shear-thinning behavior and transition from fluid-like to solid-like behavior leading to thixotropic phenomena, is expected from structural evolution. Recently, layered silicates have attracted great interest as nanoscale fillers for reinforcement of polymers (PNCs) motivating the investigation of the structural properties of non-aqueous layered silicate suspensions. At the origin of this study, the linear and nonlinear viscoelastic properties of non-aqueous layered silicate suspensions were observed to depend on flow history. Hence, the ultimate aim of this work was to establish relationships between their rheological behavior and their structural properties. The picture of their inner structure has been achieved using a combination of light scattering techniques and advanced rheometric and microscopy measurements. The flow-induced orientation of the phyllosilicate has been quantified optically using linear dichroism measurements, and mechanically using a newly developed non-destructive method based on two-dimensional small amplitude oscillatory shear flow (2D-SAOS). The spatial distribution at the microscopic scale of the phyllosilicate has been inferred from small angle light scattering (SALS) patterns and directly observed using confocal laser microscopy (CLSM). The combination of these techniques allowed highlighting the microscopic and self-similar nature of non-aqueous phyllosilicate suspensions. The solid-like properties of these suspensions were consequently ascribed to the presence of space-filling networks made of mass fractal clusters. Under flow, the shear-thinning behavior of these suspensions was explained by the shear rate dependency of the microstructure characteristic length scale. By increasing the shearing amplitude, the characteristic length scale of the non-equilibrium microstructures was shown to decrease from high to low plateau values. This structural evolution with the shearing amplitude was attributed to a reversible shear-induced aggregation. Limited structural orientational changes were also observed in the vorticity plane with anisotropy and orientation that developed in the same range of shear rate as the shear-thinning behavior of the suspensions. Upon cessation of flow, the lack of orientational recovery was explicitly shown with the 2D-SAOS experiments, while the lack of structural recovery at the micro-scale was observed in CLSM. The thixotropic behavior of these suspensions is therefore due to local rearrangements at the nano-scale. The non-equilibrium structures were actually shown to persist upon cessation of flow leading to different metastable structures. This work has allowed us to elucidate the effect of the flow history on the linear and nonlinear viscoelastic properties of these suspensions.

  14. Etude du transfert thermique conjugue dans les cavites rectangulaires en convection naturelle

    NASA Astrophysics Data System (ADS)

    Nouanegue, Herve Frank

    Energy conservation is one of the most important areas of research and development. In parallel and in conjunction with it, developing clean energy technologies using renewable energy sources is similarly an important area to provide a sustainable energy supply. In this way, the quality of life will continue to flourish and at the same time the environment will be protected. For this purpose, devices operating on the principal of passive utilization techniques are used in different applications such as solar collectors, passive cooling and heating of buildings and others. Many of these applications make use of open and/or closed enclosures having different geometries, in which heat transfer by natural convection is used often with conjunction of conduction and surface radiation. To have the best thermal performance of these devices, the understanding of conjugate heat transfer in basic geometries is essential. The aim of this thesis is to study the influence of conduction and radiation heat transfer on natural convection in rectangular enclosures with different geometries and properties. A mathematical model of the system is developed which combines heat transfer by convection, conduction and radiation. A numeric code based on the volume control method is developed to simulate open and close systems with different geometries, in which the conservation equations of mass, momentum and energy are solved using the control volume method and the radiation heat exchange equations are added by calculating radiative heat flux on the emitting surfaces and treating it as a local heat source for the conjugate heat transfer by the three modes. Four specific configurations have been studied. The first one is a closed square inclined cavity containing a massive wall. The second configuration is an open cavity. The last two configurations involve passive cooling and heating systems in which the air circulates in long vertical channels. Numerical results for all the configuration show that radiative heat transfer represents an important part of the total heat transfer for all studied configurations. In the case where surfaces are assumed to be black bodies, this part is at least 25% and can increase up to 97%, i.e. air circulation is enhanced by surface radiative exchange. On the other hand, it is shown that heat exchange by surface radiation makes the surface temperatures more uniform as a result of which natural convection is reduced. As expected, the wall conductance is an important parameter in the conduction heat transfer through the wall and hence in the thermal performance of the massive wall. More specifically for each studied case, the obtained results are the following: (i) the close cavity inclination has a significant effect on the flow field; its effect is enhanced when the heat source is placed in the upper part of the flow domain. (ii) the aspect ratio of the open cavity affects the air circulation but its influence on the heat transfer is less important; (iii) the heat transfer by natural convection increases with the wall conductance for the case of solar chimney, and thus, the ventilating capacity of the channel is enhanced; (iv) the thermal efficiency of the passive system with thermal mass is reduced when the heat exchange by surface radiation is accounted for and the temperature difference between both external vertical boundaries increases.

  15. Etudes sur la gravitation: Theories alternatives en 2+1 et 3+1 dimensions

    NASA Astrophysics Data System (ADS)

    Edery, Ariel

    This thesis contains four articles on gravitation of which three have been published in scientific journals and one has been submitted for publication. The four articles divide naturally into two parts. Chapter 1 contains two articles on conformal gravity, a 3 + 1 dimensional theory of gravity and chapter 2 contains two articles on 2 + 1 dimensional topologically massive gravity. Conformal gravity is a metric theory of gravitation which is generally covariant like Einstein gravity but also requires the action to be invariant under conformal transformations of the metric. The novel feature of the solution is a term in the metric that grows linearly with the radius. This linear term, which plays a significant role on large distance scales, can then be used to imitate the effects of the dark matter that is presumed to exist in abundance on galactic scales. In the first and second article, we test the viability of the vacuum solution of conformal gravity. In the first article we calculate the deflection of light due to a spherically symmetric source and obtain a remarkably simple result: besides the usual Einstein deflection, we obtain an extra deflection that increases linearly as the ``impact parameter'' increases (valid for small deflections). In both analyses no dark matter has been included. We explain clearly in our first article the reasons for the discrepency between the two results. In the second article, we study in detail the geometrical properties and the causal structure of the vacuum solution to conformal gravity. At infinity the space-time is not flat but conformal to flat. Through the use of Penrose (conformal) diagrams, we demonstrate that certain space- times, corresponding to certain parameters in the metric, do not allow light to scatter from infinity to infinity. For those which do, we obtain the trajectories and the deflection of light for arbitrary large values of r0 (the radius of closest approach). To simplify the study of gravity, it is common to study a 2 + 1 dimensional model. However, in 2 + 1 dimensions, the analog to Einstein gravity is trivial. The space-time outside sources is flat and particles at rest do not interact. The odd dimensional space-time allows one to include a gravitational Chern-Simons term called a topological mass term because it gives mass to the graviton. In article three and four, we consider localized mass and spin sources in the full non-linear theory. We obtain solutions for both of Vuorio's sectors. In article 3 we demonstrate that delta function sources, while allowed in the linearized theory are not consistent with the full non-linear field equations. In article four, we consider how to embed point sources in Vuorio's cosmological sector and discuss the metric solution for the case when observers are near and far away from the source. (Abstract shortened by UMI.)

  16. Etude d'un systeme de trigeneration decentralise en climats canadiens

    NASA Astrophysics Data System (ADS)

    Allaire Tanguay, Dominique

    Ce mémoire présente l'étude d'un système de trigénération ou CCHP (combined cooling, heating and power) au gaz naturel fournissant les besoins thermiques à un immeuble à logement typique de 13 étages. Un groupe électrogène permettant de générer de l'électricité tout en fournissant de l'eau chaude assure le chauffage du bâtiment et de l'eau chaude sanitaire tandis qu'une machine à absorption ammoniac-eau permet de transformer cette chaleur en puissance frigorifique afin de climatiser le bâtiment en période chaude. Le modèle de cette machine à absorption a spécialement été conçu pour fonctionner avec une température de désorption basse et permet d'évaluer les performances de telles machines dans des situations hors design. Ce modèle à été vérifié à l'aide d'autres modèles avérés et propose des coefficients de performance de l'ordre de 0,7 à 0,8. L'évaluation des performances horaires de ce système est présentée pour une année standard sous trois climats canadiens. Ces performances sont ensuite comparées aux différentes méthodes employées pour assurer ces besoins ainsi que pour générer l'électricité supplémentaire. Les résultats démontrent d'excellentes performances même lorsque comparées aux plus récentes technologies. Les résultats passent d'une légère augmentation de la consommation de gaz naturel dans un climat chaud comme Toronto à une importante réduction dans un climat froid comme Edmonton. Ce système permet donc de combler les besoins thermiques d'un bâtiment tout en générant de l'électricité dans des périodes de pointes annuelles et possiblement journalières. Plusieurs études dont notamment l'optimisation du système et le couplage à d'autres types de bâtiment permettrait cependant de mieux évaluer les possibilités complètes de la trigénération. Mots-clés : Trigénération, CCHP, Absorption, Ammoniac-eau, cogénération.

  17. Realisation d'un detecteur de radioactivite pour un systeme microfluidique

    NASA Astrophysics Data System (ADS)

    Girard Baril, Frederique

    Pour etablir le comportement pharmacocinetique de nouveaux radiotraceurs en imagerie moleculaire, il est necessaire d'approfondir l'analyse realisee a partir d'une image par l'ajout d'une mesure dynamique de la radioactivite dans le sang. L'Universite de Sherbrooke developpe presentement une plateforme microfluidique d'echantillonnage et d'analyse permettant la mesure de la radioactivite du plasma en temps reel. L'objectif du present projet de maitrise etait de realiser le composant optoelectronique responsable de la detection des positrons et de l'integrer a la puce microfluidique. L'option retenue a ete l'utilisation de photodiodes PIN en silicium. Un procede de fabrication, ainsi qu'une serie de photomasques ont ete developpes afin de produire une premiere iteration de prototypes. Les detecteurs ont ete concus de maniere a optimiser leur sensibilite en fonction du type de rayonnement a detecter. En effet, la region de detection doit etre suffisamment epaisse et sensible pour absorber le maximum de particules energetiques. Egalement, il est essentiel de minimiser le courant de fuite en noirceur afin d'obtenir un photocourant directement proportionnel a l'energie des radiations incidentes. Les caracteristiques electriques obtenues avec les premiers detecteurs ont ete demontrees proches des performances de detecteurs commerciaux similaires. De plus, il a ete possible d'integrer un canal microfluidique au substrat contenant les photodiodes et d'en realiser l'encapsulation sans alterer les performances electriques initiales des detecteurs. Une courbe de l'activite radioactive du 18F a ete mesuree, celle-ci se comparant a l'activite theorique associee a ce radioisotope communement utilise en TEP. Enfin, un spectre en energie des emissions radiatives du 18F a ete mesure et compare aux performances de systemes utilisant des photodiodes commerciales. Il a ete demontre que le prototype offrait un rapport signal sur bruit similaire aux systemes bases sur des photodiodes

  18. Case Studies On Recent Stark Broadening Calculations And Stark-B Database Development In The Framework Of The European Project Vamdc (Virtual Atomic And Molecular Data Center)

    NASA Astrophysics Data System (ADS)

    Sahal-Bréchot, S.

    2010-07-01

    Stark broadening theories and calculations have been extensively developed for about 50 years. The theory can now be considered as mature for many applications, especially for accurate spectroscopic diagnostics and modelisation. In astrophysics, with the increasing sensitivity of observations and spectral resolution, in all domains of wavelengths from far UV to infrared, it has become possible to develop realistic models of interiors and atmospheres of stars and interpret their evolution. For hot stars, especially white dwarfs, Stark broadening is the dominant collisional line broadening process. This requires the knowledge of numerous collisional line profiles, especially for very weakly abundant atoms and ions that are used as useful probes for modern spectroscopic diagnostics. Hence, calculations based on a simple but enough accurate and fast method is indispensable for obtaining numerous results. Ab initio quantum calculations are also a useful domain of development, especially for ion emitters. Nowadays, the access to such data via an on line database becomes indispensable. The Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu) is a European Union funded collaboration between groups involved in the generation and use of atomic and molecular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data. In this framework, the Stark-B (http://starkb.obspm.fr) database, which is a part of VAMDC, is a collaborative project between the Astronomical Observatory of Belgrade and the Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA). It is a database of calculated widths and shifts of isolated lines of atoms and ions due to electron and ion collisions (i.e. impacts are separated in time). This database is devoted to modelisation and spectroscopic diagnostics of stellar atmospheres and envelopes. In addition, it is relevant to

  19. Synthese de champs sonores adaptative

    NASA Astrophysics Data System (ADS)

    Gauthier, Philippe-Aubert

    La reproduction de champs acoustiques est une approche physique au probleme technologique de la spatialisation sonore. Cette these concerne l'aspect physique de la reproduction de champs acoustiques. L'objectif principal est l'amelioration de la reproduction de champs acoustiques par "synthese de champs acoustiques" ("Wave Field Synthesis", WFS), une approche connue, basee sur des hypotheses de champ libre, a l'aide du controle actif par l'ajout de capteurs de l'erreur de reproduction et d'une boucle fermee. Un premier chapitre technique (chapitre 4) expose les resultats d'appreciation objective de la WFS par simulations et mesures experimentales. L'effet indesirable de la salle de reproduction sur les qualites objectives de la WFS fut illustre. Une premiere question de recherche fut ensuite abordee (chapitre 5), a savoir s'il est possible de reproduire des champs progressifs en salle dans un paradigme physique de controle actif: cette possibilite fut prouvee. L'approche technique privilegiee, "synthese de champs adaptative" ("Adaptive Wave Field Synthesis" [AWFS]), fut definie, puis simulee (chapitre 6). Cette approche d'AWFS comporte une originalite en controle actif et en reproduction de champs acoustiques: la fonction cout quadratique representant la minimisation des erreurs de reproduction inclut une regularisation de Tikhonov avec solution a priori qui vient de la WFS. L'etude de l'AWFS a l'aide de la decomposition en valeurs singulieres (chapitre 7) a permis de comprendre les mecanismes propres a l'AWFS. C'est la deuxieme principale originalite de la these. L'algorithme FXLMS (LMS et reference filtree) est modifie pour l'AWFS (chapitre 8). Le decouplage du systeme par decomposition en valeurs singulieres est illustre dans le domaine du traitement de signal et l'AWFS basee sur le controle independant des modes de rayonnement est simulee (chapitre 8). Ce qui constitue la troisieme originalite principale de cette these. Ces simulations du traitement de signal

  20. Laser Production of Soft X-Rays by Multiquantum Processes and the Excitation of Atomic Inner-Shell States

    DTIC Science & Technology

    1989-07-06

    34Interaction des Electrons avec un Champ Intense de Rayonnement Optique ," In Polarisation, Mati~re et Rayonnement, 6dit4 par La Societe Franpaise de Physique...reflecting microscope objective (Ealing 25-0506) onto either a CCD camera or a linear photodiode array (Reticon 512G), the latter having a 25 Pm square...pixel size. The beam profile at the image plane of the microscope objective is shown in Fig. (2). An understanding of two important instrumental

  1. Inferring sublexical correspondences from sight vocabulary: evidence from 6- and 7-year-olds.

    PubMed

    Stuart, M; Masterson, J; Dixon, M; Quinlan, P

    1999-05-01

    We report an experiment designed to investigate 6-to-7-year-old children's ability to acquire knowledge of sublexical correspondences between print and sound from their reading experience. A computer database containing the printed word vocabulary of children taking part in the experiment was compiled and used to devise stimuli controlled for grapheme-phoneme correspondence (GPC) frequency and rime neighbourhood consistency according to the children's reading experience. Knowledge of GPC rules and rime units was compared by asking children to read aloud three types of nonword varying in regularity of GPC and consistency of rime pronunciation. Results supported the view that children can acquire knowledge of both GPC rules and rime units from their reading experience. GPC rule strength affects the likelihood of a GPC response; rime consistency affects the likelihood of a rime response.

  2. Sur le ternaire Tl sbnd Ge sbnd Te: Etude structurale de la phase Tl 2GeTe 5

    NASA Astrophysics Data System (ADS)

    Toure, Abdoulaye Abba; Kra, Gabrielle; Eholie, Rose; Olivier-Fourcade, Josette; Jumas, Jean-Claude; Maurin, Maurice

    1990-02-01

    Tl 2GeTe 5 is orthorhombic, space group Cmmm, with cell dimensions a = 11.657 (5), b = 11.657 (5), c = 14.917 (5), AandZ = 8. The crystal structure was determined by means of direct methods based on three-dimensional X-ray data. Atomic parameters were refined by a least-squares method to a final R value of 0.077 (507 observed reflexions). The structure can be described in terms of layers parallel to the [001] plane and characterized by (Ge 2Te 6) 4- anions and Te 4 clusters.

  3. Etude critique de la prise en charge de 159 personnes âgées en consultation de psychiatrie

    PubMed Central

    Ben Thabet, Jihène; Ammar, Yousra; Charfi, Nada; Zouari, Lobna; Zouari, Nasreddine; Gaha, Lotfi; Maalej, Mohamed

    2014-01-01

    Introduction Le phénomène de vieillissement des populations est associé à une augmentation de la prévalence de la morbidité liée à l’âge. La prescription des psychotropes chez le sujet âgé est de plus en plus fréquente dans les institutions, les doses sont de plus en plus élevées, avec un recours fréquent à une poly pharmacothérapie. Nous nous sommes proposé de décrire les conduites thérapeutiques chez le sujet âgé consultant en psychiatrie, en vue de les confronter aux dernières recommandations en la matière. Méthodes L’étude était de type rétrospectif et descriptif. Elle a concerné les sujets âgés d'au moins 60 ans ayant consulté pour la première fois en psychiatrie, au CHU Hédi Chaker à Sfax, en 2010 ou 2011. Résultats Nous avons colligé 159 dossiers. L’âge moyen était de 73 ans. La démence et les troubles de l'humeur étaient les diagnostics les plus fréquents. Sur le plan thérapeutique, une poly thérapie faite d'au moins deux psychotropes de familles différentes a été prescrite pour 55,9%. Chez 60.3% des sujets, le traitement a été prescrit d'emblée à dose complète. Aucun dossier ne faisait état d'une prise en charge psychothérapeutique. Conclusion La prise en charge des malades de notre étude n’était pas conforme aux recommandations, notamment en matière d'association médicamenteuse, de progression des doses et d'association de la psychothérapie à la pharmacothérapie. L'information des médecins et leur sensibilisation aux particularités du sujet âgé contribuerait à optimiser les soins qui leur sont prodigués, y compris en psychiatrie. PMID:25120873

  4. [Etude statistique a propos de 496 utilisatrices). (Monilial vulvovaginitis and oral contraceptives. Statistical study on 496 users)].

    PubMed

    Dugois, P; Amblard, F; Manent, J; Bignicourt B, D E

    1971-12-08

    Incidence of vaginitis due to Candida albicans confirmed by culture was 46 of 496 (9.3%) French women taking contraceptive pills. The women had used pills for a total of 5198 cycles, in which 1991 were combined lynestrenol-mestranol, 804 were norethynodrel, 525 were ethynodiol and 473 were norethisterone combinations. The study group varied widely in age, economic class, marital status and parity, but no relationship could be found between yeast infection and age, parity, marital status, miscarriages or product used. This 9.3% incidence is about the same as that in healthy women not using pills. The authors thought that virulence was increased in these pill users, although all responded to local treatment without recurrence.

  5. Etude de Retour/Non-Retour des Étudiants Marocains en France (le cas de Lille)

    NASA Astrophysics Data System (ADS)

    El Attafi, Douieb

    1990-12-01

    Indépendamment de l'intention de retour ou de non-retour, les étudiants marocains à Lille sont en général appelés à créer leurs conditions matérielles d'existence et par là, à conduire des stratégies professionnelles et sociales d'intégration à la société française bien au delà de ce qu'exigerait un simple séjour d'étude. Ces mêmes étudiants pensent qu'au Maroc, la valorisation des qualifications acquises en France est incertaine. Le chômage des diplômés au Maroc devient une réalité de plus en plus tangible. Les étudiants marocains à Lille, incertains de pouvoir s'insérer professionnellement au Maroc, lorsqu'ils réussissent à obtenir un emploi relativement déclassé, mais qualifiant, décident de rester en France. Ceci est d'autant plus probable quand, chez les étudiants, la religion n'est pas fortement intégrée. Dans le cas contraire et lorsque ils décident de rester en France, la religion comme effet durable de la socialisation primaire, constitue un point d'ancrage plus ou moins spécifique, leur permettant de réinterpréter les ruptures vécues, sous le mode de la continuité. Tout ceci montre que dans leurs choix de retour/non-retour, les étudiants sont bien évidemment conditionnés de leur histoire individuelle et collective, mais ils n'en sont pas entièrement prisonniers.

  6. Etude des melanges co-continus d'acide polylactique et d'amidon thermoplastique (PLA/TPS)

    NASA Astrophysics Data System (ADS)

    Chavez Garcia, Maria Graciela

    Les melanges co-continus sont des melanges polymeriques ou chaque composant se trouve dans une phase continue. Pour cette raison, les caracteristiques de chacun des composants se combinent et il en resulte un materiau avec une morphologie et des proprietes particulieres. L'acide polylactique (PLA) et l'amidon thermoplastique (TPS) sont des biopolymeres qui proviennent de ressources renouvelables et qui sont biodegradables. Dans ce projet, differents melanges de PLA et TPS a une haute concentration de TPS ont ete prepares dans une extrudeuse bi-vis afin de generer des structures co-continues. Grace a la technique de lixiviation selective, le TPS est enleve pour creer une structure poreuse de PLA qui a pu etre analysee au moyen de la microtomographie R-X et de la microscopie electronique a balayage MEB. L'analyse des images 2D et 3D confirme la presence de la structure co-continue dans les melanges dont la concentration en TPS. se situe entre 66% et 80%. L'effet de deux plastifiants, le glycerol seul et le melange de glycerol et de sorbitol, dans la formulation de TPS est etudie dans ce travail. De plus, nous avons evalue l'effet du PLA greffe a l'anhydride maleique (PLAg) en tant que compatibilisant. On a trouve que la phase de TPS obtenue avec le glycerol est plus grande. L'effet de recuit sur la taille de phases est aussi analyse. Grace aux memes techniques d'analyse, on a etudie l'effet du procede de moulage par injection sur la morphologie. On a constate que les pieces injectees presentent une microstructure heterogene et differente entre la surface et le centre de la piece. Pres de la surface, une peau plus riche en PLA est presente et les phases de TPS y sont allongees sous forme de lamelles. Plus au centre de la piece, une morphologie plus cellulaire est observee pour chaque phase continue. L'effet des formulations sur les proprietes mecaniques a aussi ete etudie. Les pieces injectees dont la concentration de TPS est plus grande presentent une moindre resistance a la traction. La presence du compatibilisant dans la region co-continue affecte negativement cette resistance. En considerant que l'amidon est un biomateriau abondant, moins cher et plus rapidement biodegradable, son ajout dans le PLA presente l'avantage de reduire le cout tout en augmentant la vitesse de degradation du PLA. De plus, une structure continue poreuse de PLA produit par la technique de lixiviation selective a des applications potentielles soit comme materiau a degradation rapide ou encore, une fois la phase TPS retiree, comme substrat a porosite ouverte pour la fabrication de membranes, de supports cellulaires ou de filtres. Mots-cles : melanges immiscibles, acide polylactique, amidon thermoplastique, morphologie cocontinue, lixiviation selective, microtomographie R-X, materiau rigide poreux biodegradable.

  7. Etude de la transmission sonore a travers un protecteur de type "coquilles" : modelisation numerique et validation experimentale

    NASA Astrophysics Data System (ADS)

    Boyer, Sylvain

    On estime que sur les 3,7 millions des travailleurs au Quebec, plus de 500 000 sont exposes quotidiennement a des niveaux de bruits pouvant causer des lesions de l'appareil auditif. Lorsqu'il n'est pas possible de diminuer le niveau de bruit environnant, en modifiant les sources de bruits, ou en limitant la propagation du son, le port de protecteurs auditifs individualises, telles que les coquilles, demeure l'ultime solution. Bien que vue comme une solution a court terme, elle est communement employee, du fait de son caractere peu dispendieux, de sa facilite d'implantation et de son adaptabilite a la plupart des operations en environnement bruyant. Cependant les protecteurs auditifs peuvent etre a la fois inadaptes aux travailleurs et a leur environnement et inconfortables ce qui limite leur temps de port, reduisant leur protection effective. Afin de palier a ces difficultes, un projet de recherche sur la protection auditive intitule : " Developpement d'outils et de methodes pour ameliorer et mieux evaluer la protection auditive individuelle des travailleur ", a ete mis sur pied en 2010, associant l'Ecole de technologie superieure (ETS) et l'Institut de recherche Robert-Sauve en sante et en securite du travail (IRSST). S'inscrivant dans ce programme de recherche, le present travail de doctorat s'interesse specifiquement a la protection auditive au moyen de protecteurs auditifs " passifs " de type coquille, dont l'usage presente trois problematiques specifiques presentees dans les paragraphes suivants. La premiere problematique specifique concerne l'inconfort cause par exemple par la pression statique induite par la force de serrage de l'arceau, qui peut reduire le temps de port recommande pour limiter l'exposition au bruit. Il convient alors de pouvoir donner a l'utilisateur un protecteur confortable, adapte a son environnement de travail et a son activite. La seconde problematique specifique est l'evaluation de la protection reelle apportee par le protecteur. La methode des seuils auditifs REAT (Real Ear Attenuation Threshold) aussi vu comme un "golden standard" est utilise pour quantifier la reduction du bruit mais surestime generalement la performance des protecteurs. Les techniques de mesure terrains, telles que la F-MIRE (Field Measurement in Real Ear) peuvent etre a l'avenir de meilleurs outils pour evaluer l'attenuation individuelle. Si ces techniques existent pour des bouchons d'oreilles, elles doivent etre adaptees et ameliorees pour le cas des coquilles, en determinant l'emplacement optimal des capteurs acoustiques et les facteurs de compensation individuels qui lient la mesure microphonique a la mesure qui aurait ete prise au tympan. La troisieme problematique specifique est l'optimisation de l'attenuation des coquilles pour les adapter a l'individu et a son environnement de travail. En effet, le design des coquilles est generalement base sur des concepts empiriques et des methodes essais/erreurs sur des prototypes. La piste des outils predictifs a ete tres peu etudiee jusqu'a present et meriterait d'etre approfondie. L'utilisation du prototypage virtuel, permettrait a la fois d'optimiser le design avant production, d'accelerer la phase de developpement produit et d'en reduire les couts. L'objectif general de cette these est de repondre a ces differentes problematiques par le developpement d'un modele de l'attenuation sonore d'un protecteur auditif de type coquille. A cause de la complexite de la geometrie de ces protecteurs, la methode principale de modelisation retenue a priori est la methode des elements finis (FEM). Pour atteindre cet objectif general, trois objectifs specifiques ont ete etablis et sont presentes dans les trois paragraphes suivants. (Abstract shortened by ProQuest.).

  8. The Role of Women in Foreign-Language Textbooks: A Collection of Essays. Collection d'"Etudes linguistiques" No. 24.

    ERIC Educational Resources Information Center

    Freudenstein, R., Ed.

    Essays that consider the way that women are portrayed in foreign language textbooks are presented. The selected essays were submitted to a competition sponsored by the Federation Internationale des Professeurs de Langues Vivantes, which requested that language teachers assess such concerns as: (1) whether women were described in a stereotyped way;…

  9. Etude des mecanismes de formation des microstructures lors du brasage isotherme de superalliages a base de nickel

    NASA Astrophysics Data System (ADS)

    Ruiz-Vargas, Jose

    This thesis reports theoretical and experimental investigations carried out to understand the mechanisms of microstructure formation during isothermal brazing, produced by brazing Inconel 625 and MC2 nickel-based superalloys with filler metal BNi-2. Firstly, studies were made on pure Ni to interpret microstructure's formation with simplified alloy chemistry. Microstructure formation have been studied when varying time at constant temperature (isothermal kinetics), but also when varying temperature for constant hold time (isochronal kinetics). The chemical composition and crystallography of the present phases have been identified, with the following results : (i) the fraction of dissolved base metal has been found proportional to the initial thickness of the brazing alloy, so that the composition of the liquid remains homogeneous with a precise initial equilibrium composition during the whole brazing process, (ii) the melting of the joint occurs in two steps : at lower temperature, it involves only partially melting, and boron diffusion in pure Ni leads to the precipitation of fine Ni3B borides at the interface ; in a second stage, at higher temperature, melting is complete and thermodynamic equilibrium requires significant dissolution of nickel, which also involves the dissolution of part of borides already formed. Secondly, nickel plating technique was used on Inconel 625 nickel-based superalloy. A thin layer of Ni with varying thickness, has been electrodeposited to observe the gradual dissolution of Inconel and microstructural features formation due to the presence of superalloy alloying elements. It has been observed that the nickel coating does not prevent precipitation in the base metal as boron diffuse rapidly through the coating width. In the intermediate nickel plating width, fragile precipitates of nickel borides have been observed, because the contribution of Inconel alloying elements to the melt was very limited. In absence of nickel plating on the superalloy, the formation of Nb and Cr-Mo borides phase has been observed. Efforts have been made to evaluate the accuracy of Boron measurement by energy dispersion X-ray spectroscopy (EDS) in the MC2 superalloy and BNi-2 filler metal. The most accurate method to quantify Boron using EDS is by composition difference. A precision of 5 at.% has been reached when using optimized data acquisition and post processing schemes. Ultimately, Electron Backscatter Diffraction (EBSD) combined with localized EDS analysis has been proven invaluable in conclusively identifying micrometer sized boride precipitates ; thus further improving the characterization of brazed Ni-based superalloys.

  10. Information content of the Centre d'Etude du Polymorphisme Humain (CEPH) family structures for linkage studies.

    PubMed

    Chakravarti, A

    1991-10-01

    This paper derives theoretical values for joint polymorphism information content for two markers from a family structure consisting of four grandparents, two parents, and many offspring. These data determine the efficiency of linkage map construction.

  11. Etude de la physico-chime d'un magnetoplasma de chlore pour la gravure sous-micrometrique

    NASA Astrophysics Data System (ADS)

    Pauna, Olivier Daniel

    The aim of this thesis is to achieve a better understanding of physical and chemical phenomena occurring in a high-density plasma designed for sub-micron etching of thin films. The plasma is produced in chlorine by means of an electromagnetic surface wave and it can be confined by a uniform static magnetic field. The flexibility offered by the reactor in terms of operating conditions makes possible a parametric study of the influence of the magnetic confinement on the plasma characteristics. Thus, we have examined the plasma properties by means of several diagnostics techniques, including electrostatic probes, laser photodetachment of negative ions, ion acoustic wave propagation and optical emission spectroscopy. First, we investigated the influence of the operating conditions on the spatial properties of the plasma; this includes electric characteristics (electrons, positive and negative ions) as well as chemical characteristics (reactive neutrals). Second, we studied the impact of the reactor aspect ratio (i.e. reactor length/radius ratio) on both electrical and chemical characteristics. Together with these experimental studies, we have developed a bidimensional fluid model, by solving self-consistently the first two moments of Bolzmann equation and Poisson's equation. Using a semi-implicit scheme, it was possible to maintain a short computation time and to use this model to investigate a diffusion plasma in an electropositive gas. We were thus able to estimate the value of the diffusion coefficient in the direction perpendicular to the magnetic field. The results thus obtained are in good qualitative agreement with the diffusion coefficient proposed by Liebermann and Lichtenberg.

  12. Contributions de la geographie et de la modelisation predictive a une etude de potentiel archeologique prehistorique en Gaspesie

    NASA Astrophysics Data System (ADS)

    Desrosiers, Marc

    La Gaspésie, région péninsulaire à l'extrême est du Québec, possède un héritage archéologique préhistorique riche qui s'étend de 9 000 ans jusqu'à 450 ans avant aujourd'hui. L'archéologie a livré de nombreux sites préhistoriques dans la région, surtout dans le nord de la péninsule, un constat en partie attribuable à la présence de sources de matières premières lithiques, d'axes de circulation potentielles, mais aussi à la répartition spatiale inégale des efforts de recherche. L'étude du potentiel archéologique préhistorique gaspésien, c'est la première étape de la démarche archéologique, est donc nécessaire pour orienter les travaux futurs dans cette région. Trois secteurs représentatifs de la Gaspésie ont été étudiés pour développer une nouvelle approche d'étude de potentiel : Sainte-Anne-des-Monts, le lac Sainte-Anne et New Richmond. Ensemble, ces secteurs s'étirent au travers de la péninsule sur un axe nord-sud et correspondent à un possible axe de circulation préhistorique. L'évaluation du potentiel archéologique de ces aires d'étude dépend notamment de contexte géographique gaspésien. Celui-ci est complexe, particulièrement depuis la déglaciation qui a engendré une succession de transformations du paysage. Les variations du niveau marin relatif, le passage de la toundra à un milieu forestier et d'autres changements environnementaux ont conditionné la façon dont les populations préhistoriques se sont adaptées au territoire. L'étude de potentiel dépend également des connaissances archéologiques existantes pour la région, car elles conditionnent la sélection de variables environnementales représentatives des sites connus. À partir de la confrontation des données géographiques et archéologiques, nous avons proposé des schèmes d'établissement pour les périodes chronoculturelles de la préhistoire gaspésienne. Ces patrons informationnels permettent d'illustrer la façon dont les populations préhistoriques occupaient le territoire gaspésien. C'est en appliquant ces schèmes d'établissement dans un SIG (Système d'Information Géographique) qu'il est alors possible de modéliser l'occupation potentielle du territoire au cours des périodes de la préhistoire gaspésienne. Les résultats de la modélisation sont prometteurs car les sites archéologiques connus dans le secteur de Sainte-Anne-des-Monts correspondent aux secteurs à potentiel élevé proposés par la modélisation, bien qu'une validation géomorphologique de la modélisation soit nécessaire à une étape ultérieure. Les deux autres secteurs ne présentaient pas de sites archéologiques datés qui permettaient de valider la modélisation à ces endroits. L'outil proposé est d'autant plus intéressant qu'il permet d'étudier rapidement de vastes territoires au potentiel archéologique mal évalué, comme c'est le cas de la Gaspésie.

  13. Etude d'integration fonctionnelle du cycle de developpement des produits et des communautes de pratique virtuelles

    NASA Astrophysics Data System (ADS)

    Doumit, Nancy

    Product development, subject to time constraints and system complexity, needs synchronous communication between different disciplines and locations in order to enable knowledge sharing. Being well supported, informal information flow increases productivity during product realization. Therefore, manufacturing industries are exploring the use of Enterprise Social Media (ESM) functionalities. This thesis explores the functional integration of formal information technologies such as Product Lifecycle Management (PLM) software with informal technologies as ESM through an industrial case study. Reviewing literature, the candidate has identified a gap between Virtual Communities of Practice (VCoP) and product development, as well as the correlation of PLM solutions and noncontrolled ESM in the aerospace industry. In order to disseminate a descriptive study of the current collaboration status, the author has undertaken online surveys for geodistant employees of the same department, semi-structured interviews and research among existing documentations. Subsequently, a Quality Functional Analysis is performed via two modified House of Quality matrices (PLM and ESM) to assign a convenient support for information transfer independently of its content maturity. Users' needs are categorized, and for each category a choice of platform is made with further recommendation regarding the use of the function or the need of human intervention. VCoP form an integrated part of the solution where employees support the technical content. Thus, essential roles and responsibilities are presented to maintain existing CoP and develop new ones. Finally, the candidate presents the limits of this research, gives recommendations for the manufacturing industry and suggests potential continuation of this study using PLM 2.0 with noncontrolled ESM tools.

  14. Contribution à l'Etude des Disques Planétaires et Protoplanétaires Perturbés

    NASA Astrophysics Data System (ADS)

    Charnoz, Sébastien

    2000-11-01

    Nous avons étudié plusieurs aspects dynamiques et photométriques des disques planétaires et protoplanétaires perturbés. Dans la première partie, à l'aide de modèles numériques simples, nous avons étudié l'eacute;volution thermodynamique d'un disque protoplanétaire composé de planétésimaux subissant des collisions physiques inélastiques, au voisinage d'un embryon de planète géante (~ 15 masses terrestres). Dès l'apparition de l'embryon planétaire, un transfert de chaleur se met en place dans le disque, augmentant fortement les vitesses relatives dans ce dernier, sur une région s'étendant sur plusieurs unités astronomiques. L'évolution de ce mécanisme transitoire a été étudiée sur des temps longs (un million d'années) et pour une vaste gamme demasses du perturbateur. C'est un mécanisme générique qui pourrait avoir profondément affecté le processus de formation des planètes, aussi bien telluriques que géantes. Les conséquences sur la formation de la Ceinture d'Astéroïdes sont discutées, ainsi que l'effet possible de la fragmentation des planétésimaux, qui n'a pu être prise en compte dans le modèle numérique. La deuxième partie de cette thèse est une étude photométrique de l'anneau F de Saturne, qui est perturbé par ses deux satellites gardiens. En étudiant un ensemble de plus de 300 images prises au télescope CFH, nous avons mis en évidence la présence de structures étendues, dont l'origine est toujours mal connue. En combinant nos données et celles du télescope spatial, nous avons établi avec précision une nouvelle orbite de l'anneau F, à 140060+/-60 km, soit plus faible de 150 km par rapport à celle déterminée en 1980-81. Cecipourrait être le signe qu'une important restructuration radiale de l'anneau F a dû avoir lieu entre 1980 et 1995.

  15. Integration symplectique et etude dynamique de systemes hamiltoniens: Canalisation d'une particule chargee traversant un cristal

    NASA Astrophysics Data System (ADS)

    Poulin, Robert

    1998-09-01

    Le probleme de canalisation d'une particule chargee traversant un cristal est examine dans un contexte de dynamique hamiltonienne. Nous desirons etudier la stabilite de l'espace des phases engendre par des systemes hamiltoniens a 2 degres de liberte. Ils sont issus d'un modele simple, mais realiste, applique a differentes configurations de canalisation. Afin de realiser cette analyse de stabilite, certains outils doivent etre elabores. Des integrateurs adaptifs et symplectiques, particulierement bien adaptes aux systemes hamiltoniens sont d'abord developpes. En plus d'etre performants, ils permettent la conservation des constantes du mouvement a la precision voulue. De plus, ils ont ete concus pour beneficier directement, sans aucune modification, des derniers developpements dans le domaine de l'integration symplectique. De nouvelles methodes quantitatives, basees sur l'integration symplectique et des simulations de type Monte-Carlo, sont ensuite developpees pour determiner de facon fiable la stabilite des trajectoires. Les resultats montrent que pour les systemes cristallins consideres, s'il y a transition stochastique (espace des phases passe de stable a instable), elle s'effectue de facon graduelle et non abrupte. De plus, une nouvelle forme de representation graphique permet d'examiner avec precision et flexibilite la stabilite de n'importe quel espace des phases.

  16. Etude de la variabilite des etoiles massives a l'aide de la photometrie et la spectroscopie

    NASA Astrophysics Data System (ADS)

    Lefevre, Laure

    Les étoiles Wolf-Rayet (WR) de population I sont les descendants évolués des étoiles massives de type O. Elles présentent de larges raies en émission produites par des atomes ionisés qui forment le vent stellaire chaud, den se et rapide. Il y a deux classes principales d'étoiles WR: les WN, ou les raies de l'azote dominent, et les WC (WO) ou les raies du carbone (de l'oxygène) dominent. Des observations récentes ont révelé que les vents sont "fragmentés" à petite et grande échelle, ce qui pourrait être relié en partie à des petites surdensités situées dans le vent en expansion. Cette thèse de doctorat présente la détection, l'analyse et l'interprétation, avec des outils statistiques avancés, de la variabilité dans les courbes de lumière, les vitesses radiales, et les spectres de deux étoiles WR caractéristiques (WR137 et WR123) et dans les étoiles OB observées par le satellite HIPPARCOS. Une campagne de spectroscopie intensive a été réalisée en 1999-2000 pour améliorer notre connaissance des composantes orbitales de WR137 (WC7pd+O9) et étudier les vents des WR et les conditions de formation des poussières dans de tels milieux. Le premier volet de cette thèse a permis de déduire de ces observations une orbite spectroscopique d'environ 13 ans qui confirme et précise les précédents résultats. Grace à l'analyse des spectres de cette campagne, ce travail a mis à jour une deuxième période d'oscillation de très faible amplitude de 0.83 j dans les spectres de WR137. Celle-ci pourrait être reliée aux pulsations ou à de grandes structures qui tourneraient dans le vent comme dans l'étoile EZ CMa (WR6). Une analyse en ondelettes a également permis d'isoler et de suivre pendant plusieurs heures des structures en haut des raies de CIII et CIV dans le spectre de WR137. De plus, la corrélation croisée a permis de voir que les raies formées à différentes distances de l'étoile sont probablement reliées entre elles. Enfin l'analyse des surdentsités a permis de déduire un [beta] ~ 5 nettement supérieur à la valeur de [beta] [Asymptotically to] 1 que l'on trouve dans le vent des étoiles O ( loi -[beta] de vitesse dans le vent) . Le second volet de cette thèse concerne les étoiles WN, et plus particulièrement une WN8 du nom de WR123. Les WN8 se distinguent de leur congénères WR par plusieurs caractéristiques, dont le niveau de variabilité le plus élevé de leur classe. Du fait de ces particularités, les étoiles WN8, WR123 parmi elles, ont fait l'objet de nombreuses études photométriques et spectroscopiques. Cependant l'extrême complexité des variations, combinée avec une couverture temporelle souvent inadaptée a conduit à une longue série de résultats ambigus. Avec les données exceptionnelles collectées par le premier satellite astronomique canadien MOST, ce mémoire de thèse est maintenant en mesure de répondre a une grande partie des interrogations posées. L'étoile WR123 a été observée avec MOST en mode direct toutes les 30s pendant 38 jours en juin-juillet 2004. L'analyse de Fourier montre qu'aucun signal n'est stable pour plus de quelques jours dans le domaine des basses fréquences et qu'a ucune variabilité significative n'est présente dans le domaine des hautes fréquences jusqu'à un niveau de 0.2 mmag, un ordre de magnitude plus bas que les prédictions pour les pulsations à modes étranges. Par contre, i1 semble y avoir une période de 9.8 heures présente pendant toute la durée des observations. Cette période, probablement reliée à des pulsations, pourrait permettre de mieux comprendre ce qui se passe dans les étoiles WR et leurs vents. Le troisième volet de cette thèse consiste en une analyse des différents types de variabilité des étoiles OB du catalogue HIPPARCOS. Un échantillon non biaisé de 2497 étoiles a donc été sélectionné et analysé. Il apparait que le seuil de variabilité à 99.9% établi par le consortium HIPPARCOS n'est pas représentatif de cet échantillon. Il a donc été recalculé et les étoiles (classées dans 4 catégories principales de variabilité intrinsèque ou extrinsèque) "variables" ont été réanalysées lors de cette thèse. Ce travail a permis de confirmer des résultats obtenus à partir d'échantillons trop restreints sur les super-géantes OB, de confirmer que les étoiles OBe sont très variables ([approximate] 80%) et de soulever plusieurs questions intéressantes sur les étoiles OB de la séquence principale qui sont moins variables en moyenne. On note également plus de systèmes en contact que détachés parmi les OBMS et OBe et un nombre ~ identique parmi les OBSC.

  17. Elaboration du Ge mesoporeux et etude de ses proprietes physico-chimiques en vue d'applications photovoltaiques

    NASA Astrophysics Data System (ADS)

    Tutashkonko, Sergii

    Le sujet de cette these porte sur l'elaboration du nouveau nanomateriau par la gravure electrochimique bipolaire (BEE) --- le Ge mesoporeux et sur l'analyse de ses proprietes physico-chimiques en vue de son utilisation dans des applications photovoltaiques. La formation du Ge mesoporeux par gravure electrochimique a ete precedemment rapportee dans la litterature. Cependant, le verrou technologique important des procedes de fabrication existants consistait a obtenir des couches epaisses (superieure a 500 nm) du Ge mesoporeux a la morphologie parfaitement controlee. En effet, la caracterisation physico-chimique des couches minces est beaucoup plus compliquee et le nombre de leurs applications possibles est fortement limite. Nous avons developpe un modele electrochimique qui decrit les mecanismes principaux de formation des pores ce qui nous a permis de realiser des structures epaisses du Ge mesoporeux (jusqu'au 10 mum) ayant la porosite ajustable dans une large gamme de 15% a 60%. En plus, la formation des nanostructures poreuses aux morphologies variables et bien controlees est desormais devenue possible. Enfin, la maitrise de tous ces parametres a ouvert la voie extremement prometteuse vers la realisation des structures poreuses a multi-couches a base de Ge pour des nombreuses applications innovantes et multidisciplinaires grace a la flexibilite technologique actuelle atteinte. En particulier, dans le cadre de cette these, les couches du Ge mesoporeux ont ete optimisees dans le but de realiser le procede de transfert de couches minces d'une cellule solaire a triple jonctions via une couche sacrificielle en Ge poreux. Mots-cles : Germanium meso-poreux, Gravure electrochimique bipolaire, Electrochimie des semi-conducteurs, Report des couches minces, Cellule photovoltaique

  18. Hazard Studies for Solid Propellant Rocket Motors (Etude des Risque pour les Moteurs-Fusees a Propergols Solides)

    DTIC Science & Technology

    1990-09-01

    the stresses and deformations resuii;ng from ignition pressure surge and acceleration of the Mp on ’u-ing The purpose of the scaling ds is to prevent...propellant. The hoop stress on the case is in practice the critical factor and, for this reason, all modem rocket motors are essentially cylindrical in...aziridines. The curing reaction involves formation of the amido ester, HOC[CH CH -C HCH O2-1 + kI H - CHr. ~-’- O 2 C[H GH - CHCH2,O 2CH 2 H2 NHCORCONHCH 5CH 2

  19. Etude de l'electrocatalyse de la reduction de l'oxygene sur des alliages de palladium cuivre

    NASA Astrophysics Data System (ADS)

    Fouda-Onana, Frederic

    This thesis is on the development of the ORR on Pd-Cu alloys in acid medium. Density Functional Theory (DFT) was used to determine the intrinsic properties of the alloys. The alloys were fabricated by RF sputtering on glassy carbon support and chemical salt reduction on carbon support. They characterised by electrochemical methods and correlations were made between the intrinsic properties and the experimental electrochemical parameters. These correlations were used to explain the electrocatalytic performance of the ORR on these aklooys and to determine the mechanism of this reaction on these electrocatalysts. Accordingly the following aspects were studied in details. In the first step, ab initio investigations of the effect of the intermediate adsorption on the variation of the reversible potential of the ORR on Pt(100) was shown. Density Functional Theory (DFT) was used to determine the energies and the geometry parameters of the intermediates which can be adsorbed on Pt(100) during the oxygen reduction reaction (ORR) and their effect on the . The Comparison of these energies and parameters using the Bridge or the Griffiths sites adsorption mechanism suggests that the two paths are feasible. In both mechanisms, the total adsorption energies of the intermediates species continuously decrease. Moreover, according to the geometry analysis, the O-O bond distance in H2O2 is higher in both (Bridge and Griffiths) processes compared to the gas phase. Such a result suggests a dissociative H2O2 adsorption whatever the type of the involved mechanism involved. In the second step, the Oxygen reduction reaction (ORR) on palladium-copper alloys was studied through two approaches. The first one is based on the correlations between the surface chemical composition and the kinetics parameters of the ORR. The second approach is focused on the correlations between the adsorption energies of O2 and OH of Pd-Cu(111) surfaces and the electronic properties of the alloys. The adsorbtion energy calculations are based on on ab initio calculation using the program VASP (Vienna ab initio program) in a MeDeA environnement (software purchased from Materials Design, Inc. The studies of the oxygen reduction reaction were performed in an acidic media on Palladium-Copper alloys as catalyst. The variation of the intrinsic metal surface properties (lattice parameter, binding energy, work function (Wf), d-band filling and d-band center epsilond) and O2 and OH adsorption energies of on (111) Pd-Cu surface alloys were determined using ab initio program. Calculations of these parameters were based on plane waves approach on slab system with density functional theory (DFT) using the Vienna ab initio simulation program (VASP). It was shown that insertion of Cu atoms in Pd lattice affects geometric and electronic properties of Pd. These changes influence significantly O2 and OH adsorption. In the third step, the oxygen reduction reaction (ORR) on Pd-Cu catalyst has been studied in acidic media. The palladium alloys were prepared by RF magnetron using a palladium and a copper wafer as targets on the glassy carbon substrate. The dual sputtering we used allowed the deposition of about 1micrometer thin film of Pd-Cu on glassy carbon (GC). The ORR kinetics was studied on these catalysts in 0,1M HClO4. Cyclic voltammetry (CV) was used to determine the electrochemical active surface area (Sa). An increase in Sa with the Cu content in the alloy was observed for the alloys containing more than 50% in Cu. The Pd-Cu alloys containing more than 50% in Cu exhibits a constant value of 23 cm2 for Sa. It was further shown that the ORR on the Pd-Cu alloys proceeds through the 4 electrons transfer mechanism and a Tafel slope of 60 mV/dec. The Pd 50Cu50 exhibits the highest activity for this reaction. The enhancement of the electro catalytic activity is attributed to an optimal d band property that makes easier the OOH dissociative adsorption which is considered as chemical rate determining step (RDS) for the ORR. It was also found that all the Pd-Cu alloys exhibited better electrocatalystic performances for the ORR than Pd or Cu alone. From the polarisation of the ORR in 0,1 M HClO4 it was shown that the curve of the Pd electrode was shifted to the lower potentials than those of the Pd-Cu alooys. In addition, the variation of the kinetic current of the ORR at 0,6 V vs. SCE (0,841 V vs. RHE) on the Pd-Cu alloys with the composition of in Cu content exhibited a volcano-shape. (Abstract shortened by UMI.)

  20. [Prevalence of transmission of zidovudine-resistant viruses in Switzerland. l'Etude suisse de cohorte VIH].

    PubMed

    Yerly, S; Rakik, A; Kinloch-de-Loes, S; Erb, P; Vernazza, P; Hirschel, B; Perrin, L

    1996-10-26

    Zidovudine (ZDV) was the most widely used anti-HIV drug between 1987 and 1995, and, as already reported, transmission of ZDV-resistant viruses occurs. Several mutations of the reverse transcriptase gene have been identified; one of them affects the 215 codon and is associated with a high degree of resistance. We have determined, using selective PCR, the prevalence of transmission of 215 mutant isolates in 134 patients with primary HIV infection (PHI) and have identified 8 patients with 215 mutant virus between 1989 and 1995 in Switzerland. Mutant resistant viruses have been isolated from patients treated with most antiviral drugs. A systematic search for mutant viruses may provide useful information for the adaptation of treatment strategies.

  1. Etude des defauts microscopiques et des proprietes optiques, electroniques et magnetiques du compose neodyme cerium oxyde de cuivre

    NASA Astrophysics Data System (ADS)

    Richard, Pierre

    La presente these, qui combine des mesures de diffusion Raman, de transmission infrarouge, de conductivite hyperfrequence et d'interferometrie ultrasonore sur les composes Nd 2-xCexCuO 4, traite des defauts d'oxygene, ainsi que des proprietes optiques, electroniques et magnetiques de ces materiaux. Les resultats experimentaux obtenus sont correles avec plusieurs donnees experimentales disponibles dans la litterature. D'abord, la caracterisation des modes Raman et des niveaux d'energie de champ cristallin de l'ion Nd3+ au moyen de techniques optiques, en fonction du dopage en cerium et du contenu en oxygene, permettent de conclure a la presence de defauts lies a une non-stoechiometrie en oxygene dans ces composes. En effet, des excitations de champ cristallin assignees a des ions Nd3+ en sites irreguliers sont observees, en plus des bandes d'absorption associees aux ions Nd3+ en site regulier, dans les spectres correspondant aux multiplets 4I11/2, 4I13/2 et 4I 15/2 de l'ion Nd3+. Les resultats experimentaux indiquent que, contrairement a la croyance largement repandue, les oxygenes apicaux, bien que presents dans les echantillons dopes, ne sont pas enleves lors du processus de reduction des echantillons necessaire pour faire apparaitre la supraconductivite dans cette famille de cuprates. Au contraire, des lacunes d'oxygene, dont le type varie en fonction du dopage, sont creees lors de ce processus. En particulier, il est montre dans ce travail que la reduction des echantillons dopes de maniere optimale conduit a la creation de lacunes d'oxygene dans les plans CuO2. Les consequences de telles lacunes sont largement discutees. En outre, il est suggere que de telles lacunes sont responsables de la perte de l'ordre antiferromagnetique a longue portee des ions Cu2+. Finalement, l'interaction d'echange anisotrope Nd3+-Cu 2+ dans le compose nondope est caracterisee au moyen de la transmission infrarouge sous champ magnetique. L'eclatement des doublets de Kramers mesure experimentalement est compare, en fonction de l'intensite et de l'orientation du champ magnetique externe, a des calculs d'effet Zeeman. Alors, que les calculs d'effet Zeeman ne coincident pas avec les donnees experimentales pour un champ applique perpendiculairement aux plans CuO 2, ceux-ci sont en accord avec les resultats de transmission infrarouge pour des champs superieurs a 4 T appliques parallelement a ces plans, indiquant une suppression apparente de l'interaction d'echange anisotrope Nd3+-Cu 2+ dans de telles conditions. (Abstract shortened by UMI.)

  2. Etude du diagramme ternaire CuInSe 2ZnSeIn 2Se 3

    NASA Astrophysics Data System (ADS)

    Chippaux, Daniel; Deschanvres, Alfred

    1982-11-01

    The system CuInSe 2ZnSeIn 2Se 3 has been investigated. A large domain of thiogallate-type compounds was found with a number of cation vacancies less or equal to that of ZnIn 2Se 4 compound. A study with a least-squares method was performed on the experimental parameters a and c and relations with the compositions are given. The blende-structure model with cation vacancies was used for evaluation of the vacancy radius [ r1 = (0.97 ± 0.05) Å] in the thiogallate compounds.

  3. Theoretical and Experimental Methods in Hypersonic Flows (Les Methodes Theoriques et Experimentales pour l’Etude Des Ecoulements Hypersoniques)

    DTIC Science & Technology

    1993-04-01

    AD-A267 032 AGARD-51 4 ADVISORY GROUP FOR AEROSPACE RESEARCH & DEVELOPMENT 7 RUE ANCELLE 92200 NEUILLY SUR SEINE FRANCE DTIC AGARD CONFERENCE...the authors. Published April 1993 Copyright 0 AGARD 1993 All Rights Reserved ISBN 92-835-0694- 4 Printed by Speclalised Printing r.?rvices Limited 40...oif Hypersonic Vehicles I 7 papers) - Facilitics ( 4 papers) - Instrumentation (5 papers) - (TI) Validation and Data Accuracy (7 papers j - Rarefied Gas

  4. Etude D’un Test D’Exsudation Du Trinitrotoluene (Study of an Exudation Test of Trinitrotolvene),

    DTIC Science & Technology

    1980-12-01

    doe l’oxplosif sont fondus dans un ballon doe 250 ml chauff6 5 358 K. Lorsqu’il s’agit d’un m6lange, une quantit6 conmue d’un second produit est...ajout~e au TNT fondu et agit6e A 1’aide d’une tige do verre. L𔄀chiantillon est alors vers6 dans un moule cylindrique (fig. 1), pr~alablemcnt chauff6 A

  5. Effets Seebeck et Nernst dans les cuprates: Etude de la reconstruction de la surface de Fermi sous champ magnetique intense

    NASA Astrophysics Data System (ADS)

    Laliberte, Francis

    2010-06-01

    Ce memoire presente des mesures de transport thermoelectrique, les effets Seebeck et Nernst, dans une serie d'echantillons de supraconducteurs a haute temperature critique. Des resultats obtenus recemment au Laboratoire National des Champs Magnetiques Intenses a Grenoble sur La1.7Eu0.2Sr0.1 CuO4, La1.675Eu0.2Sr0.125CuO 4, La1.64Eu0.2Sr0.16CuO4, La1.74Eu0.1Sr0.16CuO4 et La 1.4Nd0.4Sr0.2CuO4 sont analyses. Une attention particuliere est accordee aux equations de la theorie semi-classique du transport et leur validite est verifiee. La procedure experimentale et les materiaux utilises pour concevoir les montages de mesures sont expliques en detail. Enfin, un chapitre est dedie a l'explication et l'interpretation des resultats de transport thermoelectrique sur YBa2Cu3O6+delta publies au cours de l'hiver 2010 dans les revues Nature et Physical Review Letters. Les donnees d'effet Seebeck dans les echantillons de La 1.8-x,Eu0.2SrxCuO 4, ou un changement de signe est observe, permettent de conclure a la presence d'une poche d'electrons dans la surface de Fermi qui domine le transport a basse temperature dans la region sous-dopee du diagramme de phase. Cette conclusion est similaire a celle obtenue par des mesures d'effet Hall dans YBa 2Cu3O6+delta et elle cadre bien dans un scenario de reconstruction de la surface de Fermi. Les donnees d'effet Nernst recueillies indiquent que la contribution des fluctuations supraconductrices est limitee a un modeste intervalle de temperature au-dessus de la temperature critique.

  6. Etude des proprietes mecaniques statiques et dynamiques de pieces d'acier elaborees par metallurgie des poudres

    NASA Astrophysics Data System (ADS)

    Bernier, Fabrice

    The main objective of this thesis ais to gain a better understanding of the effects of processing variables on the porosity and microstructure of powder metallurgy (P/M) steel and their effect on mechanical properties, both static and dynamic. The effects of processing variables on porosity and microstructure were evaluated by advanced microstructural characterization using both optical and electron microscopies. Then the impacts of porosity and microstructure on both static and dynamic properties were measured. Static mechanical properties were characterized by hardness measurements and by tensile tests while fatigue testing was used for evaluating dynamic properties. Fractographic observations were made on tensile and fatigue fracture samples to correlate the microstructural features to the mechanical performance of P/M steels. The experimental work covered in this Ph.D. thesis enables to further understand the mechanisms by which process variables affect the microstructure and the mechanical properties of samples. In the first paper, the effect of prealloying MnS up to 1.0 wt pct on the microstructural features of non-metallic inclusions and their impact on tensile and fatigue properties of a 7.0 g/cm3 P/M steel (Fe-2.0Cu-0.7C) have been investigated. As the MnS content increases, larger, more irregular and more closely spaced inclusions are obtained. Whilst no significant impact on both static and dynamic properties was observed when prealloying up to 0.65 wt pct MnS, a decrease of more than 15 pct of the ultimate tensile strength and of the endurance limit was found when the MnS content reaches 1.0 wt pct. The decrease in the ultimate tensile strength is attributed to a lower ductility of the sinternecks, as void initiation and void growth were promoted at lower stress levels by larger inclusions. The larger size of the MnS particles and the lower mean free path between non-metallic inclusions also favor microcrack initiation and their coalescence into cracks, leading to premature fatigue fracture. In the second paper, the improvement of performance that can be achieved by copper infiltration was quantified. Tensile and fatigue properties of a Fe-2.0Cu-0.7C PM steel were compared to the same alloy infiltrated with 8 wt-% copper. Microstructural characterization, using optical and electron microscopies, was carried out to understand the effect of copper infiltration on mechanical properties. Copper infiltration improves the ultimate tensile strength by 40% by increasing the load bearing section, decreasing the stress concentrations associated to open porosity and increasing the hardness of the steel matrix. Fractographic observations show the evidence of stress transmission from the sinternecks to the steel particles due to infiltrated copper. The beneficial effect of copper infiltration is less pronounced for fatigue properties as the endurance limit is increased by only 10%. This lower improvement is explained by crack initiation at the copper/steel matrix interface. In the last paper, the microstructural characterization of nickel rich areas and their influence on the endurance limit of a P/M steel was investigated. The addition of nickel powder to a P/M steel increases hardenability, enabling the formation of martensite directly after the sintering process. However, the slow diffusion rate of nickel into iron leads to the formation of nickel rich areas (NRA). Two steel alloys were studied, the first one is a Fe-6.4Ni-0.7Mo-0.7C with standard size nickel powder additions and the second one is a Fe-2.4-0.7Mo-0.7C where a finer size nickel powder was added. The influence of the size of the nickel powder used on hardenability and on the presence of NRA has been investigated by optical microscopy. A complete identification of the microstructural constituents and the effect of nickel concentration on their presence were achieved using X-ray energy dispersive spectrometry and electron diffraction in the transmission electron microscope. Results obtained by these techniques show the presence of austenite and martensite. Fatigue tests were carried out on P/M steel parts with and without austenitic areas to study their impact on the endurance limit. The analysis of the results showed that these areas are not a governing factor for the endurance limit of sintered steels. (Abstract shortened by UMI.)

  7. Etude de la microstructure d'un acier 316 titane apres vieillissement et apres irradiation aux neutrons

    NASA Astrophysics Data System (ADS)

    Brun, G.; Le Naour, J.; Vouillon, M.

    1981-10-01

    La précipitation qui se produit lors de vieillissements de longue durée entre 450 et 700°C dans un acier 316 Ti soit hypertrempé soit écroui, a été étudiée en couplant les techniques de microscopic électronique et de microanalyse X. Pour les cas expérimentaux étudiés, les résultats obtenus montrent que la composition des carbures M 23C 6 et des phases σ, Laves et χ est peu sensible aux conditions de vieillissement et dépend également peu de l'état structural initial. Leur teneur en éléments principaux de l'alliage est d'ailleurs voisine de celle des phases précipitées dans l'acier non stabilisé. Excepté les carbures de type M 6C, toutes ces phases ont une teneur en nickel inférieure à celle de la matrice. Les premiers rérultats obtenus sur des matériaux irradiés aux neutrons montrent que la précipitation sous flux est différente de celle qui se produit dans l'acier vieilli. Les phases γ' et G ainsi que les carbures riches en nickel ont été observés. L'attention a été attirée sur le fait qu'il n'y a pas de corrélation simple entre la vitesse de gonflement et la teneuer résiduelle en nickel de la matrice.

  8. The Pedagogical Value of Leo Brouwer's "Etudes Simples": A Perspective on Preserving an Exquisite, Yet Neglected Custom

    ERIC Educational Resources Information Center

    Kronenberg, Clive W.

    2013-01-01

    The decline in the status of the classical guitar is, for many, a cause of concern, calling for viable answers to restore its place in the expressive arts tradition. In this article, I explore a pedagogical style specifically intended for young and/or inexperienced players. It is argued that this endeavor could prospectively benefit a range of…

  9. INTRODUCTION A UNE ANNEE D'ETUDES A PARIS (INTRODUCTION TO A YEAR OF STUDY IN PARIS).

    ERIC Educational Resources Information Center

    Paris Univ. (France).

    THIS BROCHURE PRESENTS A SIMPLIFIED DESCRIPTION OF HIGHER EDUCATION AS DISPENSED BY THE FIVE SCHOOLS OF THE UNIVERSITY OF PARIS AND THE REQUIREMENTS FOR DIFFERENT LEVELS OF INSTRUCTION. THERE ARE SECTIONS ON THE SCHOOLS OF LAW AND ECONOMIC SCIENCE, MEDICINE, SCIENCE, LETTERS AND HUMANITIES, AND PHARMACY. SPECIAL COURSES FOR FOREIGNERS IN LANGUAGE,…

  10. Etude onomasiologique k'un vocabulaire politique: le vocabulaire europeen (Onomastic Study of a Political Vocabulary: The European Vocabulary)

    ERIC Educational Resources Information Center

    Schumacher, Nestor

    1974-01-01

    This article studies the linguistic phenomena that accompany the development of a common French-German political terminology. Important stages are the coexistence of similar terms, fixation of terms, appearance of key words, and polarization of terms. (Text is in French) (AM)

  11. Study Abroad, Etude a l'etranger, Estudios en el extranjero: 1972-1973, 1973-1974.

    ERIC Educational Resources Information Center

    United Nations Educational, Scientific, and Cultural Organization, Paris (France).

    This book provides information on scholarships, travel, grants, assistance with fees, internships, international courses, and special courses for foreign students. The programs described are for students of all ages from undergraduate level upwards, for their tutors, advisors, parents, libraries, and reference services. More than 250,000…

  12. Survey of Hyperspectral and Multispectral Imaging Technologies (Etude sur les technologies d’imagerie hyperspectrale et multispectrale)

    DTIC Science & Technology

    2007-05-01

    Prism-Grating-Prism Imaging Spectrograph 3-4 Figure 5 Basic Principle of the IMSS 3-5 Figure 6 Optical Scheme of Sagnac and Michelson Imaging...the dispersive techniques in imaging spectrometers applications is the Image Multi- Spectral Sensing ( IMSS ) technology, developed and patented by...Pacific Advanced Technology since 1992.The IMSS is based on the principle of diffractive optics; as such it is a combination of a diffractive imaging

  13. Etude des Abondances de MG et de fe dans la Composante Stellaire des Disques des Galaxies Spirales

    NASA Astrophysics Data System (ADS)

    Beauchamp, Dominique

    Je presente ici une technique d'observation par imagerie des disques stellaires des galaxies spirales. Je tente, a l'aide d'un modele evolutif multiphase, de determiner les abondances de fer et de magnesium dans les disques. Dans ce but, je mesure les indices Mg2 et Fe5270 du systeme de Lick. Ces elements representent un choix judicieux d'indicateurs car ils sont formes par des supernovae de deux types differents ayant des durees de vie differentes. Le rapport d'abondances de ces deux elements est un indicateur du taux de formation des populations stellaires. Je decris, en premier lieu, les observations, la technique de mesure, ainsi que son application. J'analyse ensuite les indices mesures. A partir du modele multiphase, j'explore differents parametres physiques des spirales comme le taux de formation stellaire, l'evolution des abondances, les effets possibles de la presence de la barre, etc.

  14. Etude exploratoire de la commercialisation des nanotechnologies au Canada: L'utilisation de la fouille de donnees de contenu Web

    NASA Astrophysics Data System (ADS)

    Rietsch, Constant

    Companies rely more every day on the Internet, sharing a lot of information to their customers but also their investors and their associates. Most companies share information such as products, services, partnerships, and research and development activities on their website. All this information is much analytical opportunities provided that we can retrieve and interpret. In this context, is the content of a website can be enough to conduct a study on innovation and commercialization? Websites are sources of information available and accessible to everyone. The majority of companies with a website, the coverage of an Internet-based study is an advantage. For our research on the commercialization of nanotechnology in Canada, we recover as many data on websites of Canadian companies listed by various sources as having activities in nanotechnology. From these data we cluster companies according to their nanotechnology field using a list of keywords from scientific papers to estimate the level of advancement of Canadian companies in nanotechnology research. Finally thanks to several indicators of innovation and marketing we describe the current state of nanotechnology in the Canadian industry.

  15. Etude vibrationnelle d'aluminates et de gallates de terres rares—II. Gallates de structure pérovskite

    NASA Astrophysics Data System (ADS)

    Saine, M. C.; Husson, E.; Brusset, H.

    The i.r. spectra of some gallates LnGaO 3 (Ln = La, Pr, Nd) with perovskite structure and the Raman spectrum of NdGaO 3 are presented and analysed. The force field, calculated for the three compounds, is stronger than for homologous aluminates. The GaO bonds which are parallel to the C2 axis are stronger than the others, thus showing the existence of a privileged direction. This effect decreases from La to Nd compounds.

  16. Etude vibrationnelle d'aluminates et de gallates de terres rares—III. Aluminates et gallates de structure grenat

    NASA Astrophysics Data System (ADS)

    Saine, M. C.; Husson, E.; Brusset, H.; de, A. Cerez

    The i.r. absorption and Raman scattering spectra of some aluminium and gallium garnets have been studied. They show a stronger force field in the aluminates than in the gallates and the influence of the ionic radius of the Ln 3+ cation on the frequencies of the aluminium—oxygen or gallium—oxygen network. The study of the system Er 3Ga 5O 12-Er 3Al 5O 12 permitted us to propose an assignment of the different ranges of frequencies and to point out that the tetrahedra vibrations are higher than the octahedra ones. The i.r. spectrum of the perovskite NdGaO 3 is compared to the garnet Nd 3GasO 12 one.

  17. Etude vibrationnelle d'aluminates et de gallates de terres rares—IV. Aluminates de samarium et d'europium

    NASA Astrophysics Data System (ADS)

    Saine, M. C.; Husson, E.

    In order to complete our studies on rare earth aluminates and gallates of perovskite structure, we have calculated a force field for orthorhombic SmAlO 3 and EuAlO 3. This force field is anisotropic with regard to the ab plane of the structure and is slightly weaker than the force field of the rhombohedral aluminates LaAlO 3 or NdAlO 3.

  18. Etude vibrationnelle d'aluminates et de gallates de terres rares—I. Alluminates de structure pérovskite

    NASA Astrophysics Data System (ADS)

    Saine, M. C.; Husson, E.; Brusset, H.; Cerez, A.

    The i.r. spectra of some aluminates of rhomboedral and orthorhombic perovskite types are presented and analysed. The complete vibrational analysis of NdAlO 3 is presented and a force field is proposed for this type of compounds; the potential energy distribution is given and the normal modes are drawn using ORTEP program.

  19. Etude de l’hémogramme dans la drépanocytose homozygote: à propos de 87 patients

    PubMed Central

    Dahmani, Fatima; Benkirane, Souad; Kouzih, Jaafar; Woumki, Aziz; Mamad, Hassan; Masrar, Azlarab

    2016-01-01

    La drépanocytose homozygote, fait partie des hémoglobinopathies les plus fréquentes au Maroc. La drépanocytose est caractérisée par une grande variabilité d’expressions clinique et biologique qui dépendent des facteurs génétiques modulateurs et environnementaux. Elle se manifeste par une anémie régénérative de gravité très variable selon les individus. L’évolution spontanée en l’absence de traitement est le décès précoce. La drépanocytose est caractérisée par une grande variabilité d’expression clinique et biologique qui dépend des facteurs génétiques et environnementaux. Un tableau clinique sévère marqué par une fréquence de transfusion élevée et précoce, des complications infectieuses graves et une mortalité précoce. Un état inflammatoire constant caractérisé par des protéines inflammatoires élevées et état nutritionnel compromis. L’objectif est de déterminer le profil des paramètres hématologiques du drépanocytaire homozygote (SS) marocain au cours des stades stationnaires. Nous avons fait une étude descriptive transversale de 87 patients drépanocytaires (SS). Nous avons réalisé une étude biologique comportant: l’hémogramme avec étude morphologique des globules rouges en coloration MGG et numération automatique des réticulocytes. Les électrophorèses de l’hémoglobine à pH alcalin (8.8) sur gel d’agarose avec intégration densitométrique. L’âge moyen est de 13.22 ans ± 16.36 avec un sex- ratio (H/F) de 1.175 et des extrêmes allant de 0.6 à 36 ans. La répercussion de l’anémie sur le plan biologique, est intense chez 88.5% des patients, 67.8% ont une anémie normocytaire contre 29.9% présentant une microcytose, et 2.3% qui présentaient une macrocytose. Le degré d’anisocytose est lié au degré d’anémie, très évocatrice chez les drépanocytaires homozygotes S/S (95,4%). Une réticulocytose était observée chez nos patients (81,6%) et 52.9% présentaient une thrombocytose. Une leucocytose était observée chez 64.4% des patients et 80.5% ont présenté une neutropénie. Les paramètres de l’hémogramme serviront de base de comparaison lors des crises et permettront d’évaluer l’efficacité de la prise en charge par le clinicien. Les valeurs élevées des globules blancs, plaquettes et CCHM semblent déterminants dans l’expression sévère de la drépanocytose au Maroc. Le profil hématologique du drépanocytaire marocain montre des données semblables à celles rapportées en littérature chez ceux de l’Afrique centrale, avec une leucocytose. Les résultats de notre étude suggèrent que, la drépanocytose est un problème de santé le plus fréquent chez les marocains et que nos résultats sont comparables à ceux décrits dans le syndrome drépanocytaire majeur. PMID:28293356

  20. Etude de la transition tribologique entre le fretting et le meso-fretting pour des materiaux de contact electrique

    NASA Astrophysics Data System (ADS)

    Gagnon, Daniel

    Dans les installations electriques, les contacts sont toujours soumis a des contraintes alternees ou a des micro-deplacements. Il en resulte une corrosion par fretting, phenomene defini comme un type de deterioration de la surface qui se produit lorsque deux materiaux en contact sont soumis a des mouvements microscopiques d'oscillations de tres faible amplitude (0 a 100 mum). Ceci a pour effet de provoquer une degradation de la resistance de contact et une interruption du passage du courant. Ce phenomene a des repercussions considerables sur le plan pratique puisque les micro-deplacements de pieces en contact peuvent etre causes par la dilatation thermique differentielle des metaux, par des vibrations mecaniques, par la relaxation des contraintes ou par l'echauffement des contacts lorsqu'on interrompt et retablit le courant. Nous avons donc dans le cadre de cette these etudie plusieurs aspects du fretting (0--100 mum) et du meso-fretting (100 a 1000 mum) pour differents materiaux de contact electrique. Des travaux experimentaux ont ete realises a partir de deux montages reproduisant divers aspects de la degradation par le fretting. Un premier montage de fretting de type bille-plaque a ete entierement developpe a l'ETS et un second montage, de type fil-plaque a ete utilise en collaboration avec Hydro Quebec IREQ a Varennes. Plusieurs techniques de mesures et d'analyse relevant tant du domaine de la mecanique du contact que de la metallurgie ont ete utilisees pour traiter les resultats. L'influence du courant sur le taux d'usure et la force de friction a ete examinee pour divers materiaux de contacts. Des essais de fatigue thermique et electrique ont ete realises sur divers materiaux et lubrifiants de contact. Il a ete demontre que pour le domaine entre 100 mum et 1000 mum, le taux d'usure n'est pas le meme de 0 a 100 mum et au dela de 1000 mum. La plupart des materiaux evalues montrent un stade de comportement intermediaire dont le debut se situe entre 100 mum et 300 mum. Lorsque l'on substitut le courant CC a un courant CA de 60 Hz ou 400 HZ, la morphologie des debris aux abords de la zone de contact est differente. De plus, lors de la comparaison du vieillissement thermique par conduction versus par chauffage electrique de certains alliages sans plomb, il a ete montre qu'il pourrait y avoir une difference entre les deux en ce qui concerne le taux de croissance des phases intermetalliques.

  1. Etude de la performance de piles a combustible microbiennes et l'effet des materiaux d'electrodes

    NASA Astrophysics Data System (ADS)

    Martin, Edith

    Recent climate change has brought a whole new dimension to the energy field since now we must change our primary source, fossil fuels. The microbial fuel cell (MFC) technology emerged as a result of recent efforts in the development of alternative sources of energy. This project aims to improve the performance maximization of such celsl. It is assumed that the microbial fuel cells' functioning is influenced by the operation conditions as well as the biofilm development and other limitations. It is also appropriate to suppose that the electrode materials also have consequences on either the microorganisms' activity or the electrochemical reaction reactivity. Thus, various operating conditions and configurations are tested to identify the specific effects of these changes on cell performance. Also, the development of the biofilm is extensively studied under various conditions to improve the electrons transfer between the active biofilm and the anode. These experiments and analyses permitted to identify various effects that can improve the microbial fuel cell performance. Thus, the influence of organic load (of glucose and acetate), pH and operating temperature of the fuel cell has been shown and optimal values were determined, leading to a significant increase in the anodic biofilm activity and a decrease of the methanogens activity, the latter reducing the coulombic efficiency by diverting a non-negligible substrate amount for their benefit. Hence, organic loading of 2 to 4 g L-1 day-1, pH between 6,25 and 6,5 as well as high cathode temperature (62 °C) but moderate anode temperature (30 °C) caused a maximum power generation increase to 19,2 W m -3. During the experiments with acetate as substrate, distance between electrodes and fuel cell volume have been reduced, leading to a power density of 92,4 W m-3. All these observations are the subject of the first article presented in this thesis. Since the microbial fuel cell power generation depends on the number of anode-reducing microorganisms populating the biofilm, this relationship was deepened in the second manuscript. This article, which intended to monitor the biofilm development, highlights the influence of external load changing rate during the active biofilm growth. Thus, when the external load is adjusted rapidly to approach the cell internal resistance, electrons exchange is enhanced as well as the proliferation of microorganisms responsible of these electrons generation. By promoting faster anode-reducing microorganisms growth, other species are somewhat disadvantaged and substrate consumption is primarily involved in the electricity production rather than any other unwanted products (eg.: methane). This article also demonstrates the influence of the biofilm development level on the diffusion limitation of the anodic reaction, a limitation that becomes more pronounced as the biofilm grows. The third article clarifies the diffusion limitation of the charge transfer at the anode. Therefore, the organic load variation of acetate in microbial fuel cells with carbon felt (3D) and carbon paper (2D) anodes as well as the electrolyte conductivity decrease has targeted protons diffusion out of the biofilm as the current generation limitation. In addition, a secondary electrochemical reaction has been identified at the anode, creating an electrode resistance increase and thereby a slight power output decrease. Finally, multiple electrochemical analyses helped to establish with certainty that the electron transfer mechanism carried out by anode-reducing microorganisms is by direct contact with the anode via microorganisms themselves or the conductive biofilm matrix, cytochromes being responsible for the electrons transport in both cases. The last manuscript deals with new cathode materials (carbon, Mn 2O3 and Fe2O3) evaluation in comparison to a platinum cathode. These materials were chosen for their potential to stimulate the proliferation of microorganisms capable of influencing cathode activity in order to obtain a biocathode; however, this phenomenon has not been verified. (Abstract shortened by UMI.)

  2. Introduction à L'Etude de la Médecine Expérimentale. Surgical revolution. Part I.

    PubMed

    Toledo-Pereyra, Luis H

    2009-01-01

    Claude Bernard (1813-1878), the most distinguished French physiologist of the 19th century, made incomparable contributions to the world of medicine of his times and even to ours. Bernard believed in scientific determinism and created the term milieu interieur as a manner to better understand experimental medicine and to present a new way of explaining the function of the living organism. Bernard dealt with innovative developments in the glycogenetic function of the liver, extrahepatic glycogenesis, the role of pancreatic juice in the digestion of fats, vasomotor nervous system discoveries, and other important physiological advances. In 1865, Bernard's most extraordinary book on the philosophy and understanding of experimental medicine appeared. This book represented Bernard's unique contribution to the progress of medical and surgical research. Because of the enormous implications of this work on the advancement of surgical research, which were subsequently applied to clinical surgical practice, we propose that this book created a surgical revolution.

  3. Etude experimentale de l'utilisation des revetements glaciophobes et/ou hydrophobes sur les pales d'eoliennes

    NASA Astrophysics Data System (ADS)

    Adomou, Maryelle C.

    2011-12-01

    Blade icing is a major problem of windmill use in northern climates. At present, the use of anti-icing protection on blades is little used because it is energy intensive and unsafe. An interesting current alternative is the use of ice-shedding coatings because they are proving to be less energy hungry, but their efficiency and durability have yet to be proven in windmills. Since windmills have a special dynamic structure and icing events can be of several types, an understanding of the accretion process on a variety of coatings is necessary to advance general knowledge in this field. To explore this problem, experiments were performed in the refrigerated wind tunnel at the Anti-icing Materials International Laboratory of the Universite du Quebec a Chicoutimi on a static-blade section covered with three commercial ice-shedding coatings chosen using well-defined criteria. Experimental conditions were based on several real extreme icing events. Scaling of the parameters of the icing events gave two air speeds for the wind tunnel (21 and 33m/s), two air temperatures (5 and -20°C) and one humidity level (0.4g/m 3). The experimental runs were carried out on blades covered with the coatings alone and also in combination with an electrothermal deicing system. The efficiency of the apparatus was evaluated by analysing the shape of the ice formed, the energy consumption of each anti-icing and de-icing combination and also by analysing the internal distribution of temperatures in the system. When used as a protective anti-icing system, none of the icephobic coatings was effective in reducing ice accumulation significantly on the blades. However, combined with an electrothermal anti-icing system, these types of coatings proved to be effective. Nevertheless, the power must be high enough to cause runoff. Hydrophobic coatings reduce energy consumption of electric anti-icing systems by about 7% whereas a super hydrophobic coating can reduce energy consumption by more than twice this amount. In de-icing mode and using a super hydrophobic coating, a reduction of 15% was recorded. These power reductions are largely due to the hydrophobic nature of the surfaces.

  4. Etude de solutions pour la mise en oeuvre d'une antenne a reflecteur bi-grille en polarisation circulaire

    NASA Astrophysics Data System (ADS)

    Joyal, Marc-Andre

    Dual-gridded reflector (DGR) antennas are widely used on satellites. They consist of a cascade of two parabolic grids operating in orthogonal linear polarizations, each one having its own feed. Therefore, DGRs are actually two antennas in one structure, so they use less space on the satellite. Moreover, they provide excellent isolation between adjacent coverage areas. The disadvantage with these DGRs is that they work only in linear polarization (vertical and horizontal). In this thesis, two different solutions to design a circularly polarized (right and left hand circular polarizations) DGR are explored. The first one consists in the use of circular polarizers that are fixed on a conventional DGR. Those polarizers are surfaces that make the conversion between linear and circular polarizations. The other solution uses circular polarization selective surfaces (CPSSs) as reflectors on the DGR instead of the orthogonal grids. These CPSSs are structures that are transparent to one sense of circular polarization (say right hand circular polarization for instance), but that reflect the other sense (left hand circular polarization). The major part of this work is based on the first solution. A new circular polarizer design method is proposed. It allows a greater flexibility in the polarizer design than existing designs. The proposed technique is also modified in order to implement polarizers optimized for an oblique incidence, which is required for DGR applications. The second solution using CPSSs is only briefly explored. A new type of CPSS, implemented with a cascade of circular and linear polarizers, is proposed. This cascade CPSS has shown a broader bandwidth than those obtained with the resonant structures known so far. Also, the limitations of CPSSs are identified as to their use on DGRs. Finally, as a proof of concept, two simple prototypes of circularly polarized DGRs are presented. The first design is implemented with a circular polarizer and a metallic grid attached to a small reflector. The second prototype is similar, but the planar grid is replaced by a reflectarray that plays the same role, but increases the gain in the direction of the main beam. The satellite industry requirements between 18-20 GHz are respected with this latter implementation, but only for a very low variation in the elevation angle.

  5. Initiating Franco-American Studies: A Handbook for Teachers = Manuel du professeur pour introduire les etudes Franco-Americaines.

    ERIC Educational Resources Information Center

    Freeman, Stanley L., Jr.; Pelletier, Raymond J.

    This five-chapter handbook is designed for use by teachers in elementary and secondary schools and adult education. Its purpose is to achieve more widespread awareness and understanding of the Franco-American presence in New England by offering teaching plans and strategies for incorporating materials into the existing humanities curriculum. It…

  6. Mathematics Comparison Study Companion Database = Base de Donnees Accompagnant L'Etude Comparative Portant sur les Mathematiques.

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Curriculum Standards Branch.

    This companion database to the Mathematics Comparison Study consists of the entire set of all the general and specific outcomes that were referenced in the report. The database is being released in response to requests made during the review of the draft document in June, 1999, for more information. In the main report, only codings for the general…

  7. MISE EN EVIDENCE ET ETUDE CYTOCHIMIQUE D'UNE PROTEINE BASIQUE EXTRANUCLEAIRE DANS LES SPERMATOZOIDES DES CRUSTACES DECAPODES

    PubMed Central

    Chevaillier, Philippe

    1967-01-01

    Extranuclear basic proteins have been detected in the capsule of the spermatozoa of three species of decapod crustaceans (Nephrops norvegicus L., Macrura; Eupagurus bernhardus L., Anomura; Carcinus maenas Penn., Brachyura). Their properties have been studied by cytochemical methods. Their position inside the capsule of the spermatozoon has been specified with the aid of the electron microscope. Present in a constant fashion in the three species cited, their relative importance is very variable. In contrast to the refringent cone of the spermatozoon of Ascaris, which contains an acid protein, ascaradine, the capsule of the spermatozoon of the three decapod crustaceans studied contains basic proteins which we propose to designate by the general term "decapodine". PMID:6068078

  8. Etude séro-épidémiologique de la leishmaniose canine au centre du Maroc

    PubMed Central

    Fellah, Hajiba; Doughmi, Oursula; Maniar, Saâd; Lalami, Abdelhakim El Ouali

    2014-01-01

    Dans le monde, la leishmaniose viscérale humaine est connue pour avoir comme principale source d'infection les Canidés domestiques et sauvages. Au centre du Maroc, les données épidémiologiques, cliniques et parasitologiques sur la leishmaniose canine, sont quasiment inexistantes. Ce travail traite une étude prospective au cours de laquelle 61 sérums canins ont été analysés par un test rapide et par l'immunofluorescence indirecte. La sensibilité du test rapide par rapport à celle de l'immunofluorescence indirecte (IFI) est de 33,33%. La fréquence de la maladie chez les chiens s’élève à 9,83% (Test Rapide) et 24,59% (IFI). 73,33% des cas canins positifs à la sérologie sont asymptomatiques. Ce sont les jeunes chiens de moins de 5 ans qui sont les plus fréquemment atteints avec une sensibilité de la race Berger Allmand à l'infection. Cette étude a permis de mettre en évidence la présence de chiens leishmaniens (15 chiens séropositifs parmi 61) et de prouver l'existence du réservoir canin. Une stratégie de prévention active doit être mise en place. PMID:25852791

  9. Etude comparative en luminescence UV-visible du 1,1'-binaphtyle et du 2,2'-binaphtyle

    NASA Astrophysics Data System (ADS)

    Fadouach, M.; Benali, B.; Kadiri, A.; Cazeau-Dubroca, C.; Nouchi, G.

    1992-10-01

    The modifications of emission spectra obtained in fluid and rigid media as a function of temperature show a conformation change for 1,1'-binaphthyl in the excited state. This change is facilitated in fluid medium by the rotation of the two naphthyl groups around the C 1C 1' bond. The molecular twisting in this excited state explains the original results for 1,1'-binaphthyl where the intensity ratio of phosphorescence to fluorescence ( Iph/ Ifluo) varies with excitation wavelength. This result agrees with the charge transfer (CT) character obtained by the excited state S* 2 due to the twist of this molecule. The emission spectra of 2,2'-binaphthyl, a molecule which is practically identical in its electronic structure to 1,1'-binaphthyl, do not undergo significant modification with effects of temperature variation, and as a function of the excitation wavelength. These different effects for 1,1'-binaphthyl and 2,2'-binaphthyl agree with the difference of twist for the naphthyl rings around the single bond between these rings.

  10. Mutations des roles techniques et formation. Etude documentaire (Changes in the Roles and Education of Technicians. Documentary Study).

    ERIC Educational Resources Information Center

    Pinard, Helene

    Drawing from research conducted in 1990-91, this report examines trends affecting the future work of technicians in Quebec, their pre-employment education, and the link between college and work. Part 1 focuses on aspects of the economic, technological, and social environment that will influence the future role of technicians. Economic concerns…

  11. Strategie pour une etude de la chanson francaise (A Strategy for the Study of the French Song)

    ERIC Educational Resources Information Center

    Chamberlain, Alan

    1977-01-01

    Teaching a song has been relegated to the "reward for learning the subjunctive" category in most French classes. A well defined program, including a sample lesson plan, integrating the song into the French course is offered. Four objectives of such a program are outlined. (Text is in French.) (AMH)

  12. The Role of Women in Foreign-Language Textbooks: A Collection of Essays. Collection d'"Etudes linguistiques" No. 24.

    ERIC Educational Resources Information Center

    Freudenstein, R., Ed.

    Essays that consider the way that women are portrayed in foreign language textbooks are presented. The selected essays were submitted to a competition sponsored by the Federation Internationale des Professeurs de Langues Vivantes, which requested that language teachers assess such concerns as: (1) whether women were described in a stereotyped way;…

  13. Etude de la variabilite climatique des hautes latitudes nord, derivee d'observations satellites micro-ondes

    NASA Astrophysics Data System (ADS)

    Mialon, Arnaud

    Observing sub-polar ecosystems is important as they are suspected to change significantly in response to the expected increase in temperature for the next decades. To bypass the lack of meteorological stations in the Northern High Latitudes, remote sensing is an interesting alternative tool, covering almost the entire area. This project deals with the development of a method to derive surface parameters (>50°N) from satellite data. For this study, brightness temperature data acquired by the SSM/I (Special Sensor Microwave Imager) in the microwave spectrum are used because they are independent of solar radiation and weakly influenced by the atmosphere. Methods used are based on brightness temperatures measured at 19 and 37 GHz, which allow to derive three geophysical parameters related to climate variability: daily maps of snowcover between 1988 and 2002; a water surface extent (open water, small lakes, reservoirs, wetlands associated with low vegetation); a temperature characterizing the surface and the air above the ground. A method to normalize the temperature is presented to overcome the variation of the time of measurement. It leads to hourly series of temperature, This allows to study climate indicators such as the annual sum of positive degree days. Trends confirm observed climate evolution: increase of surface temperature (+0.8 +/- 0.4°C for Canada/Alaska between 1992 and 2002), decrease in snow extent cover. These original databases could also be useful for validation of regional climate model. (Abstract shortened by UMI.)

  14. Etude onomasiologique k'un vocabulaire politique: le vocabulaire europeen (Onomastic Study of a Political Vocabulary: The European Vocabulary)

    ERIC Educational Resources Information Center

    Schumacher, Nestor

    1974-01-01

    This article studies the linguistic phenomena that accompany the development of a common French-German political terminology. Important stages are the coexistence of similar terms, fixation of terms, appearance of key words, and polarization of terms. (Text is in French) (AM)

  15. Etude de production et de caracterisation de biocharbons de panic erige (Panicum virgatum L.) obtenus par pyrolyse

    NASA Astrophysics Data System (ADS)

    Pilon, Guillaume

    This research aimed at the production of biomass char under pyrolytic conditions, targeting biochar as soil amendment, while also considering its application as biocoal, either for bioenergy or subsequent upgrading. The production of biomass char was performed using two bench-scale, batch-type, fixed-bed reactors, each with an operating capacity of 1 and 25 gw.b. /batch, respectively. Switchgrass (Panicum virgatum) has been used for the tests. Production conditions studied implied temperatures of 300, 400 and 500 °C with short residence times (2.5 and 5 min). As well, the effect of using CO2 as vector gas has been compared to a common inert environment of N2. The effects of the previously mentioned parameters were correlated with some important physicochemical characteristics of biomass char. Analyses were also performed on complementary pyrolytic products (bio-oil and gas). The biomass char extraction was performed using a Soxhlet and dichloromethane was used as extracting solvent. The extracts were then characterized by GC-MS thus allowing the identification of several compounds. Specific pyrolysis conditions used at 300 °C - N2 with the 1 g/batch reactor, such as high heating rates as well as high convection conditions, presented advantegeous biomass char yields and properties, and, possible torrefaction process productivity improvement (in comparison to reported literature, such as Gilbert et al. [2009]). The char extracts as well as the bio-oils analysis (also performed using GC-MS), all generated from the 25 g/batch reactor, showed major differences among the compounds obtained from the CO2 and N2 environments, respectively. Several compounds observed in the char extracts appeared less concentrated in the CO2 environment vs N2, for the same reaction temperatures. As an example, at 400 °C, furfural was found only in char extracts from N2 environment as compared to the CO2 environment. Among all studied conditions (for both reactors), only naphthalene and naphthalene derivatives constituted the PAHs content, which was only detected for the chars produced at 500 °C. The use of CO2 as pyrolysis vector gas led to a significant difference for every temperature conditions studied for the biomass char as well as for the liquid and gas products. At 300 °C, in CO 2 environment, it is possible to observe a bio-oil production significantly lower than within a N2 environment (18.0 vs 24.6 %; CO2 vs N2 for P<0.002), a result consistent with the biomass char volatile content that was shown to be significantly higher under the same conditions (0.29 vs 0.35 gchar volatiles content/graw biomass; P=0.1). In addition, at 500 °C, the char ash content was observed to be significantly lower in CO 2 than in N2 (P<0.06). Keywords: Pyrolysis, torrefaction, char, biochar, biocoal, CO 2, Soxhlet extractions, characterization.

  16. The Pedagogical Value of Leo Brouwer's "Etudes Simples": A Perspective on Preserving an Exquisite, Yet Neglected Custom

    ERIC Educational Resources Information Center

    Kronenberg, Clive W.

    2013-01-01

    The decline in the status of the classical guitar is, for many, a cause of concern, calling for viable answers to restore its place in the expressive arts tradition. In this article, I explore a pedagogical style specifically intended for young and/or inexperienced players. It is argued that this endeavor could prospectively benefit a range of…

  17. Etude de sensibilite du profil de durete des engrenages traites thermiquement par induction en fonction des parametres machine

    NASA Astrophysics Data System (ADS)

    Barka, Noureddine

    This project involves a study of sensitivity of the hardness profile of cylindrical bars and spur gears heated by induction using finite element models (axisymmetric and 2D) combined with experimental tests. This sensitivity study is considered as the basic step towards the development of prediction models. The study mainly aims at evaluating the effect of material properties and machine parameters on the hardness profile. As the induction heating is very fast, it is reasonable to assume that the material properties are different from those measured under thermodynamic equilibrium conditions. For this reason, the study attempts to measure the effect of variations in material properties on the surface temperature using the axisymmetric model. The results show that the relative magnetic permeability is the property that most significantly influences surface temperatures and the variation of this property has a large effect on the hardness profile. The effects of specific heat and electrical conductivity are rather low, while the thermal conductivity has a negligible effect on the model developed. Moreover, the variation in temperature of austenitizing margins have limited effects on the developed model. Therefore, the use of material properties at thermodynamic equilibrium was sufficient to establish models for predicting trends. Moreover, study of global sensitivity profile of hardness as a function of machine parameters allowed, in the first place, to compare the two cases of heat to medium and high frequency, by applying them to a disc and a gear and determine the effect of the imposed current density and heating time on the hardness profile using the results of the simulations. It appears that the edge effect is smaller in the MF heating case. In addition, the 2D model can confirm that the MF power heat more the tooth root, while the HF power heat the tooth tip region. Finally, the regression models developed were used to estimate surface temperatures and depths hardened with time of heating and power received by the part. The experimental tests, performed on discs and gears with the same exterior dimensions, have confirmed a clear correlation between hardness profiles measured and those obtained by simulation. Moreover, since the power transmitted by the machine to the coil is not known and it is difficult to measure the current in the inductor, the issue was to find a method leading to a match between simulation and experimentation. Indeed, tests have allowed the calibration of developed models by evaluating the power ratio between the power received by the part and that provided by the machine. Thus, the calibrated models are able to predict global trends of the hardness profile as a function of machine parameters even if the material properties measured at thermodynamic equilibrium are used. Finally, a local sensitivity analysis was performed by varying the machine parameters slightly around the nominal values leading to a definite hardness profile. Based on the statistical tools of variance analysis, this study showed that the hardness profile is very sensitive to small variations of the power machine and the heating time in the case of the disc. With regard to the gears and considering the dual frequency sequential heating mode, HF power and HF heating time are the parameters that most affect the hardness profile. Although the study focused on the specific geometry and a given material, it is clear that the models developed can be used to develop mechanical components and they help reduce the development time. The greatest contribution of this work has been to bridge the gap between theory, simulation and practice. Therefore, it laid the groundwork to achieve a more general and robust model capable of supporting the interactions between the machine parameters, variables, dimensions and material properties. The accuracy of the model could be greatly improved by considering inductor current measurement during heating and material properties characterization in thermodynamic nonequilibrium conditions. (Abstract shortened by UMI.)

  18. Economie et enseignement a Madagascar. (Economy and Education in Madagascar.) Financement des systemes educatifs: etudes de cas Nationales 8.

    ERIC Educational Resources Information Center

    Hugon, Philippe

    The purpose of this volume is to analyze the problems of school finance in Madagascar, including those that have arisen in the past decade and those anticipated in the present decade (through 1980). More generally, this book examines past and future connections between the economic and educational systems in Madagascar. The author examines the…

  19. Coping Strategies in Reading: Multi-Readers in the Norwegian General Education System

    ERIC Educational Resources Information Center

    Vik, Astrid Kristin; Fellenius, Kerstin

    2007-01-01

    Six primary school-aged braille students were taught to name 4 to 10 braille letters as phonemes and another 4 to 10 braille letters as graphemes (Study 1). They were then taught to name 10 braille words as onset-rimes and another 10 braille words as whole words (Study 2). Instruction in phonemes and onset rimes resulted in fewer trials and a…

  20. Teaching Adults to Read Braille Using Phonological Methods: Single-Case Studies

    ERIC Educational Resources Information Center

    Crawford, Shauna; Elliott, Robert T.

    2009-01-01

    Four women with visual impairments were taught 13 braille letters as phonemes and another 13 braille letters as graphemes and then were taught 10 braille words as onset-rime and another 10 braille words as whole words. Phoneme and onset-rime instruction resulted in faster and more accurate performance. (Contains 1 table and 2 figures.)

  1. Influence of Consonantal Context on the Pronunciation of Vowels: A Comparison of Human Readers and Computational Models

    ERIC Educational Resources Information Center

    Treiman, Rebecca; Kessler, Brett; Bick, Suzanne

    2003-01-01

    In two experiments, we found that college students' pronunciations of vowels in nonwords are influenced both by preceding and following consonants. The predominance of rimes in previous studies of reading does not appear to arise because readers are unable to pick up associations that cross the onset-rime boundary, but rather because English has…

  2. Context-Sensitive Regularities in English Vowel Spelling.

    ERIC Educational Resources Information Center

    Aronoff, Mark; Koch, Eric

    1996-01-01

    Compares the predictive value of rime spellings in English to other types of regularities beyond the level of the single letter. Computer-analyzes a list of 24,000 written words, each paired with its corresponding pronunciation. Reveals that only a small number of rime spellings are highly regular in pronunciations. Suggests English spelling is…

  3. Learning New Words Affects Nonword Pronunciation in Children

    ERIC Educational Resources Information Center

    Khanna, Maya M.; Cortese, Michael J.; Birchwood, Katharine S.

    2010-01-01

    In two experiments we examined how children's nonword pronunciations are influenced by learning words. In Experiment 1, children pronounced nonwords before and after learning words sharing orthographic rimes with the nonwords. These rimes varied in spelling-to-sound consistency and regularity. Children's nonword pronunciations were more sensitive…

  4. On the Representation of Mandarin Syllable Structure.

    ERIC Educational Resources Information Center

    Kuo, Feng-Lan

    1994-01-01

    This paper argues that Mandarin Chinese has a fixed syllabic represented by the template CGVX, with one slot in the onset and three slots in the rimeprime (as projection of the rime). It claims that the pre-nucleus glide is obligatory, is an independent constituent, and is adjoined to the rime constituent. Extensive evidence for this template is…

  5. Beginning Word Recognition: Benefits of Training by Segmentation and Whole Word Methods.

    ERIC Educational Resources Information Center

    Levy, Betty Ann; Lysynchuk, Linda

    1997-01-01

    Compares effectiveness of four different methods for acquiring initial reading vocabulary--onset plus vowel, rimes, phoneme segmentation and blending, and simple repetition of whole words. Finds that beginning nonreaders acquired the trained words fastest in the onset and rime conditions, and most slowly in the whole word condition. Finds the same…

  6. Technical Programme 1993 (Le Programme Technique, 1993)

    DTIC Science & Technology

    1992-09-01

    Symposium sur "Les Effets de la Propagation Atmospherique a travers des Obscurcissants Naturels et Artificiels sur le Rayonnement des Ondes Millimetriques...for Small Gas Turbines" Reunion du Panel et Symposium sur "Les Technologies pour les Petites Turbines a Gaz " 4-8 CANADA TIP Panel Meeting/Specialists

  7. Radiations cosmiques : danger dans l'Espace

    NASA Astrophysics Data System (ADS)

    Bonnet-Bidaud, J. M.; Dzitko, H.

    2000-06-01

    Au sol, l'atmosphere nous protege plus ou moins bien. Mais dans l'espace ou a bord des avions de ligne, l'homme est directement expose aux rayonnements cosmiques qui peuvent etre mortels. Un veritable frein a la presence humaine prolongee dans l'espace. Une menace que les agences spatiales prennent tres au serieux.

  8. Evaluation of Mixed-Phase Microphysics Within Winter Storms using Field Data and In Situ Observations

    NASA Technical Reports Server (NTRS)

    Colle, Brian A.; Yu, Ruyi; Molthan, Andrew L.; Nesbitt, Stephen

    2014-01-01

    It is hypothesized that microphysical predictions have greater uncertainties/errors when there are complex interactions that result from mixedphased processes like riming. Use Global Precipitation Measurement (GPM) Mission ground validation studies in Ontario, Canada to verify and improve parameterizations

  9. Errors in short-term memory for speech: a developmental study.

    PubMed

    Treiman, R

    1995-09-01

    In a previous study (R. Treiman & C. Danis, 1988), adults who were presented with lists of spoken consonant-vowel-consonant (CVC) nonsense syllables for immediate recall produced many errors that combined the initial consonant onset of one to-be-remembered syllable with the vowel-consonant rime of another to-be-remembered syllable. These onset-rime recombination errors were more common than other types of recombination errors and also more common than serial position errors. These findings suggest that nonwords are remembered in terms of smaller phonological units. To replicate the previous results and to determine whether they generalize to children, the author tested kindergarteners, 3rd graders, 6th graders, and adults on lists of nonsense CVCs. Onset-rime conjunction errors were the most frequent type of recombination error, even among kindergarteners, suggesting that children code spoken syllables in terms of onset and rime units from a young age.

  10. Searching near-replicas of images via clustering

    NASA Astrophysics Data System (ADS)

    Chang, Edward Y.; Li, Chen; Wang, James Z.; Mork, Peter; Wiederhold, Gio

    1999-08-01

    Internet piracy has been one of the major concerns for Web publishing. In this study we present a system, RIME, that we have prototyped for detecting unauthorized image copying on the WWW. To speed up the copy detection, RIME uses a new clustering/hashing approach that first clusters similar images on adjacent disk cylinders and then builds indexes to access the clusters made in this way. Searching for the replicas of an image often takes just one IO to loop up the location of the cluster containing similar objects and one sequential file IO to read in this cluster. Our experimental results show that RIME can detect images copies both more efficiently and effectively than the traditional content- based image retrieval systems that use tree-like structures to index images. In addition, RIME copes well with image format conversion, resampling, requantization and geometric transformation.

  11. Development of phonological awareness in bilingual chinese children.

    PubMed

    Chen, Xi; Ku, Yu-Min; Koyama, Emiko; Anderson, Richard C; Li, Wenling

    2008-11-01

    This study investigated the phonological awareness of 219 first, second, and fourth grade Cantonese-speaking children from the south of China, who received immersion Mandarin instruction beginning in the first grade. Children received onset, rime and tone awareness tasks in Cantonese and Mandarin. Children performed better on the Cantonese onset awareness task in grade one, but the difference disappeared in higher grades. However, their performance on the rime and tone awareness tasks was better in Mandarin. These results reflect the phonological structure of the two languages: Mandarin has a more complex onset system, whereas Cantonese has more complex tone and rime systems. Moreover, children's phonological awareness increased faster in Mandarin, which likely resulted from Mandarin instruction. Confirmatory factor analysis suggested that onset-rime awareness is a universal construct, whereas tone awareness is a language-specific construct.

  12. Cantonese Consonantal Developmental: Towards a Nonlinear Account.

    ERIC Educational Resources Information Center

    Wong, Winnie W-Y.; Stokes, Stephanie F.

    2001-01-01

    Provides a preliminary description of phonological tier development in Cantonese-speaking children. Data were analyzed for word, syllable, onset-rime, skeletal, and segmental tiers. Results suggest a developmental order in acquisition of hierarchical features. (Author/VWL)

  13. Developpement de techniques de diagnostic non intrusif par tomographie optique

    NASA Astrophysics Data System (ADS)

    Dubot, Fabien

    Que ce soit dans les domaines des procedes industriels ou de l'imagerie medicale, on a assiste ces deux dernieres decennies a un developpement croissant des techniques optiques de diagnostic. L'engouement pour ces methodes repose principalement sur le fait qu'elles sont totalement non invasives, qu'elle utilisent des sources de rayonnement non nocives pour l'homme et l'environnement et qu'elles sont relativement peu couteuses et faciles a mettre en oeuvre comparees aux autres techniques d'imagerie. Une de ces techniques est la Tomographie Optique Diffuse (TOD). Cette methode d'imagerie tridimensionnelle consiste a caracteriser les proprietes radiatives d'un Milieu Semi-Transparent (MST) a partir de mesures optiques dans le proche infrarouge obtenues a l'aide d'un ensemble de sources et detecteurs situes sur la frontiere du domaine sonde. Elle repose notamment sur un modele direct de propagation de la lumiere dans le MST, fournissant les predictions, et un algorithme de minimisation d'une fonction de cout integrant les predictions et les mesures, permettant la reconstruction des parametres d'interet. Dans ce travail, le modele direct est l'approximation diffuse de l'equation de transfert radiatif dans le regime frequentiel tandis que les parametres d'interet sont les distributions spatiales des coefficients d'absorption et de diffusion reduit. Cette these est consacree au developpement d'une methode inverse robuste pour la resolution du probleme de TOD dans le domaine frequentiel. Pour repondre a cet objectif, ce travail est structure en trois parties qui constituent les principaux axes de la these. Premierement, une comparaison des algorithmes de Gauss-Newton amorti et de Broyden- Fletcher-Goldfarb-Shanno (BFGS) est proposee dans le cas bidimensionnel. Deux methodes de regularisation sont combinees pour chacun des deux algorithmes, a savoir la reduction de la dimension de l'espace de controle basee sur le maillage et la regularisation par penalisation de Tikhonov

  14. Montblanc1: GPU accelerated radio interferometer measurement equations in support of Bayesian inference for radio observations

    NASA Astrophysics Data System (ADS)

    Perkins, S. J.; Marais, P. C.; Zwart, J. T. L.; Natarajan, I.; Tasse, C.; Smirnov, O.

    2015-09-01

    We present Montblanc, a GPU implementation of the Radio interferometer measurement equation (RIME) in support of the Bayesian inference for radio observations (BIRO) technique. BIRO uses Bayesian inference to select sky models that best match the visibilities observed by a radio interferometer. To accomplish this, BIRO evaluates the RIME multiple times, varying sky model parameters to produce multiple model visibilities. χ2 values computed from the model and observed visibilities are used as likelihood values to drive the Bayesian sampling process and select the best sky model. As most of the elements of the RIME and χ2 calculation are independent of one another, they are highly amenable to parallel computation. Additionally, Montblanc caters for iterative RIME evaluation to produce multiple χ2 values. Modified model parameters are transferred to the GPU between each iteration. We implemented Montblanc as a Python package based upon NVIDIA's CUDA architecture. As such, it is easy to extend and implement different pipelines. At present, Montblanc supports point and Gaussian morphologies, but is designed for easy addition of new source profiles. Montblanc's RIME implementation is performant: On an NVIDIA K40, it is approximately 250 times faster than MEQTREES on a dual hexacore Intel E5-2620v2 CPU. Compared to the OSKAR simulator's GPU-implemented RIME components it is 7.7 and 12 times faster on the same K40 for single and double-precision floating point respectively. However, OSKAR's RIME implementation is more general than Montblanc's BIRO-tailored RIME. Theoretical analysis of Montblanc's dominant CUDA kernel suggests that it is memory bound. In practice, profiling shows that is balanced between compute and memory, as much of the data required by the problem is retained in L1 and L2 caches.

  15. Assessment of Superstructure Ice Protection as Applied to Offshore Oil Operations Safety: Problems, Hazards, Needs, and Potential Transfer Technologies

    DTIC Science & Technology

    2008-09-01

    14 16 Rime Ice Location Brown and Agnew (1985) found rime icing to be most frequent in the Arc - tic in Canadian waters, and attribute it to high... arcing and loss of communication (Crowley 1988). Liljestrom and Lindgren (1983) indicate that icing can cause equipment damage, malfunctions...catch spray and ice and submerging them periodically to remove the ice (Makkonen 1984), deflecting droplets using air curtains (Minsk 1977), and

  16. An Experimental Study of Airfoil Icing Characteristics

    NASA Technical Reports Server (NTRS)

    Shaw, R. J.; Sotos, R. G.; Solano, F. R.

    1982-01-01

    A full scale general aviation wing with a NACA 63 sub 2 A415 airfoil section was tested to determine icing characteristics for representative rime and glaze icing conditions. Measurements were made of ice accretion shapes and resultant wing section drag coefficient levels. It was found that the NACA 63 sub 2 A415 wing section was less sensitive to rime and glaze icing encounters for climb conditions.

  17. Prostate Cancer Risk in Relation to IGF-1 and its Genetic Determinants: A Case Control Study Within the Cancer Prostate Sweden Project (CAPS)

    DTIC Science & Technology

    2007-05-01

    www.interscience. wiley.com). Abbreviations: CAPS, Cancer Prostate in Sweden; CEPH, Centre d’Etude du Polymorphisme Humain; htSNPs, haplotype tagging...downloading genotype data for 30 Caucasian Centre d’Etude du Polymorphisme Humain (CEPH) trios from the HapMap Phase 1 data base,15 covering the IGF1

  18. Actes du colloque sur le bilinguisme, Universite de Neuchatel, 14/15 Septembre, 1981 (Proceedings of the Colloquium on Bilingualism, University of Neuchatel, September 14-15, 1981).

    ERIC Educational Resources Information Center

    TRANEL, 1982

    1982-01-01

    This issue contains proceedings of a colloquium on linguistics at the University of Neuchatel: (1) "Propositions epistemologiques pour une etude du bilinguisme (Epistemological Propositions for a Study of Bilingualism)," by B. Py; (2) "Comment on di ca? Prolegomenes a une etude de la composante semantique du langage des migrants (How Do You Say…

  19. Actes du colloque sur le bilinguisme, Universite de Neuchatel, 14/15 Septembre, 1981 (Proceedings of the Colloquium on Bilingualism, University of Neuchatel, September 14-15, 1981).

    ERIC Educational Resources Information Center

    TRANEL, 1982

    1982-01-01

    This issue contains proceedings of a colloquium on linguistics at the University of Neuchatel: (1) "Propositions epistemologiques pour une etude du bilinguisme (Epistemological Propositions for a Study of Bilingualism)," by B. Py; (2) "Comment on di ca? Prolegomenes a une etude de la composante semantique du langage des migrants (How Do You Say…

  20. New Fluoride Glasses for the Preparation of Infrared Optical Fibers.

    DTIC Science & Technology

    1987-09-01

    LUCAS, University of Rennes Contractor: CENTRE REGIONAL ETUDES BRETAGNE SCIENCES, CREBS PRESIDENCE DE L’UNIVERSITE, Rue du Thabor - 35000 RENNES (France...OFFICE NAME AND ADDRESS 1Z. REPORT OATE CENTRE REGIONAL ETUDES BRETAGNE SCIENCES Sept. 1986 - Sept. 1987 I"’. NUMBER OF PAGES Pr~sidence Ic

  1. Laser Speckle from Thin and Cascaded Diffusers

    DTIC Science & Technology

    1988-05-01

    24. N. G. Gaggioli and M. L. Roblin, "Etudes des etats de surface par les properties de diffusion a l’infini en lumiere transmise," Opt. Commun. 32...N. G. Gaggioli and M. L. Roblin, "Etudes des etats de surface par les properties de diffusion a l’infini en lumiere transmise," Opt. Commun. 32, 209

  2. Etude des propriétés optiques des couches minces de CuInS2 et d'In-S " Airless spray "

    NASA Astrophysics Data System (ADS)

    Kamoun, N.; Bennaceur, R.; Frigerio, J. M.

    1994-05-01

    In this work we have studied the optical properties of the thin CuInS2 and In-S layers prepared by airless spray " P.S.A. ". The study of the optical properties from the ellipsometric measure realized in the interval energy of incident photons [1.5-4] eV, has showed that the refraction index n_1 and the extinction coefficient k_1 vary in the interval [1.8-2.3] and [0.45-0.80] respectively. The absorption coefficient α of the thin CuInS2 layers realized for different ratios x of the concentrations in the spray solution (x =frac[CuI][InIII]) is high with values varied between (5 × 10^4 and 18 × 10^4 cm^{-1}). The direct gap energy of the thin CuInS2 layers of the order of 1.38 eV. In the same way, we study the spectrum variation of n_1 (λ) and k_1 (λ) of the thin In-S layers, realized for two values of ratio y of the concentration in the spray solution (y=frac{[In^{3+}]}{[S^{2-}]}), shows that for the value of y = 0.6 (material β-In2S3) the refraction index is higher than that of the thin layer obtained for the value of y = 0.75 (material In6S7) [1], and that the extinction coefficient is lower than that of In6S7. For In-S thin layers, α is also high with values varing between 2×10^4 and 12×10^4 cm^{-1}. The direct band gap of materials β-In2S3 and In6S7 are 2.22 eV and 1.94 eV respectively. The heat treatment under vacuum at 573 K during two hours improves the optical quality of the thin " p " type CuInS2 Layer. Dans ce travail nous avons étudié les propriétés optiques des couches minces de CuInS2 et d'In-S réalisées par pulvérisation chimique réactive sans air " P.S.A. ". L'étude des propriétés optiques des couches minces de CuInS2, à partir des mesures ellipsométriques effectuées dans le domaine des photons incidents [1,5-4] eV, a révélé que l'indice de réfraction n_1 et le coefficient d'extinction k_1 varient respectivement dans les domaines [1,8-2,3] et [0,45-0,80]. Le coefficient d'absorption α, des couches minces de CuInS2 réalisées pour différents rapports x des concentrations de cuivre et d'indium dans la solution de spray (x =frac[CuI][InIII]) est élevé avec des valeurs comprises entre 5 × 10^4 et 18 × 10^4 cm^{-1}. Le gap des couches minces de CuInS2 est direct, il est de l'ordre de 1,38 eV. ~ ~De même, nous avons étudié des spectres de variation n_1 (λ) et k_1 (λ) des couches minces d'In-S, réalisées pour deux valeurs du rapport y des concentrations dans la solution de spray (y=frac{[In^{3+}]}{[S^{2-}]}=0,6 matériau β-In2S3 et y = 0,75 matériau In_6S_7 [1]). Pour les couches minces d'In-S, α est aussi élevé, il est compris entre 2 × 10^4 et 12 ×10^4 cm^{-1}. Les gaps directs des matériaux β-In2S3 et In6S7 sont respectivement de l'ordre de 2,22 eV et 1,94 eV. Le traitement thermique sous vide pendant deux heures à 573 K améliore la qualité optique des couches minces de CuInS2 de type " p ".

  3. Etude de contacts métal-InP(n) clivé : barrière de Schottky et états d'interface

    NASA Astrophysics Data System (ADS)

    Maaref, H.; Barret, C.

    1991-05-01

    Au, Ag, AI and Pd-InP (n type) interfaces have been obtained by UHV cleavage and in situ metallization. These interfaces have been characterized by electrical methods : I- V, C- V, SCS (Shottky Capacitance Spectroscopy). In spite of great variations in the reactivities of the deposited metals on InP, the Schottky barrier heights are quite similar: 0.37 eV (AI) ; 0.41 eV (An, Pd) ; 0.54 eV (Ag). The study of interface states by SCs shows the presence of two characteristic states whatever the metal localized near E_c - 0,25 eV and E_c - 0,37 eV. The latter could play a significant role in the Fermi level pinning. Des interfaces Au, Ag, AI et Pd-InP de type n ont été réalisées par clivage et métallisation in situ sous ultra-vide. Les caractérisations ont été effectuées par des méthodes électriques I-V, C-V et SCS (Spectroscopie de Capacité Schottky). Malgré les importantes différences de réactivité entre les métaux utilisés et InP les barrières de Schottky varient peu: 0,37 eV pour AI, 0,41 eV pour Au et Pd et 0,54 eV pour Ag. L'analyse des états d'interface par SCS met en évidence deux états communs à toutes les interfaces et localisés au voisinage de E_c - 0,25 eV et E_c - 0,37 eV. Ce dernier pourrait jouer un rôle important dans l'ancrage du niveau de Fermi.

  4. Transition vers les energies renouvelables: Etude de l'energie eolienne et maremotrice dans le contexte neo-brunswickois selon une perspective socio-economique

    NASA Astrophysics Data System (ADS)

    Bizid, Mohamed Abdelkader

    Gold nanorods (GNRs) are of interest for numerous applications, especially for biomedical applications because of their surface plasmon resonance. Application of external magnetic fields can direct the assembly of magnetic nanoparticles. There are few reports, however, of incorporating magnetic materials onto the surface of GNRs. A significant challenge for some approaches of magnetic overcoating is the high temperature that is often required for deposition of magnetic materials. Because GNRs are temperature sensitive, we have developed a method, where GNRs are first overcoated with a thermally stable SiO2 shell, which also serves as an adhesion layer for further deposition of Fe3 O4 as an outer shell. Results for the assembly of Fe 3O4-overcoated GNRs in applied magnetic fields are also reported. To best form a core-shell structure of GNRs, knowledge of their physical properties, surface chemistry, stability, and synthesis method is essential, and background on each of the topics is introduced in the first part of this dissertation. The major technical advances reported in this dissertation include the following: (1) The milestones of large-scale synthesis of GNRs with tunable aspect ratio and SiO2-overcoated GNRs (SiO2-GNRs) with tunable shell thickness (2-20 nm) have been achieved. Functionalization of GNRs and SiO2-GNRs with poly(ethylene glycol) (PEG) has also been accomplished, and these samples have been provided to collaborations for studies of photothermal heating and optical coherence tomography (OCT). (2) The shape stability of GNRs and SiO2-GNRs while heating under vacuum was investigated through in situ transmission electron microscopy (TEM), which revealed that SiO2-GNRs (16 nm thick shell) can maintain their rod shape up to at least 1200 °C. (3) Subsequent overcoating with Fe3O4 provides multifunctional GNRs, which assemble into chains in applied magnetic fields. The Fe3O4 overcoating consists of Fe3O4 nanoparticles embedded in the SiO 2 shell. Future modification of the Fe3O4 overcoating may allow for control over the alignment of GNRs in applied magnetic fields. In the last part of the dissertation, contributions to selected collaborative projects are summarized. For several studies, I have provided GNRs or have performed TEM.

  5. Canadian Mathematics Education Study Group = Groupe Canadien d'Etude en Didactique des Mathematiques. Proceedings of the Annual Meeting (Kingston, Ontario, Canada, May 29-June 2, 1987).

    ERIC Educational Resources Information Center

    Mendoza, Lionel P., Ed.; Williams, Edgar R., Ed.

    These conference proceedings include three invited lectures, a panel discussion, three working group reports, two reports from topic groups and a participant list. The invited lectures include a discussion of the impact of calculators on the calculus curriculum (Herbert S. Wilf); a consideration of the role of misconceptions in learning…

  6. Etude par diffraction neutronique de la phase ``Cs4-xYb12F40-x'' (0 <= x <= 1): Hypothèse structurale

    NASA Astrophysics Data System (ADS)

    Aléonard, S.; Lambert, B.; Pannetier, J.; Gorius, M. F.; Roux, M. Th.

    1985-07-01

    The structure of the phase Cs 4- xYb 12F 40- x(0 ≤ x ≤ 1) has been determined by a single-crystal neutron diffraction study. It has been solved in the space group P6 3mc and refined to the best R factor of 0.0535 for the formula Cs 3.4Yb 12F 39.4 (324 independent reflections). Three edge-sharing pentagonal bipyramids surrounding three ytterbium atoms form Yb 3F 16 groups and the structure is described as the superposition, according to the sequence A1A2B1B2A1A2…, of sheets of corner-sharing Yb 3F 16 groups with a possible transformation of bipyramids into octahedra in the A2 and B2 layers. These sheets are joined together by the axial fluorine atoms of the bipyramids or octahedra. Cesium atoms are located in the tunnels formed by their stacking. It is shown that the Cs 4- xYb 12F 40- x phase (0 ≤ x ≤ 1) is an intermediate step of the Cs 4- xYb 12F 40- x solid solution observed with 0 ≤ x ≤ 2 and corresponds to a superstructure of the high-temperature YbF 3 phase.

  7. Etude microdosimetrique de l'influence des materiaux sur l'efficacite biologique d'une source d'iode-125

    NASA Astrophysics Data System (ADS)

    Taschereau, Richard

    Cette these concerne les implants permanents pour la prostate. Les isotopes employes, le 103Pd et l'125I, semblent produire les memes resultats cliniques: le premier a cause d'une radiation plus efficace et le second a cause de sa demi-vie plus longue. La recherche utilise le cadre theorique de la microdosimetrie et des simulations Monte Carlo. Elle propose d'employer le spectre d'ejection dans le calcul de l'efficacite; ce changement fait passer l'efficacite relative du 103Pd de 10% a 5%. Elle montre ensuite qu'il est possible d'ameliorer l'efficacite de la radiation de 125I par l'exploitation des rayons X caracteristiques de la capsule. Une source amelioree faite de molybdene et d'yttrium est donnee en exemple. Elle procure une radiation de 5--7% plus efficace, ce qui surclasse les deux sources existantes. Les applications ne se limitent pas au traitement de la prostate; le traitement du melanome oculaire et la curietherapie endovasculaire pourraient en beneficier.

  8. Etude par Imagerie à faible Niveau dans le proche Infrarouge d'une Emission de la haute Atmosphère

    NASA Astrophysics Data System (ADS)

    Pautet, Pierre-Dominique

    2000-12-01

    Le travail effectué a eu pour but la mise en place d'un protocole d'observation et de traitement des images, ainsi que les outils appropriés, visant à l'étude d'une émission de la haute atmosphère terrestre dans le proche infrarouge. Il existe actuellement des télescopes comme le VLT (Very Large Telescope), installé au Chili, qui permettent d'observer des astres et des galaxies distants de plusieurs millions de parsecs. A cause de l'expansion de l'Univers, des objets situés aussi loin s'éloignent très rapidement de nous. Le spectre de leur émission qui nous parvient alors est décalé vers le rouge ou l'infrarouge, du fait de l'effet Doppler. Il faut donc observer ces objets dans des longueurs d'onde appropriées. Malheureusement, l'atmosphère terrestre qui nous sépare d'eux est aussi le siège de nombreuses émissions qui peuvent venir perturber les mesures. De toutes ces émissions, la principale est due au radical OH dont les raies de rotation-vibration couvrent tout le spectre entre 0,7 et 2,5 microns. Cette émission a lieu au niveau d'une couche assez fine de la haute atmosphère appelée mésopause et située à environ 85 kilomètres d'altitude. Le travail effectué a eu pour but de mettre en évidence les principales caractéristiques de cette émission qui n'est pas uniforme et constante dans le temps. Un programme d'observations dans le proche infrarouge a été élaboré. Plusieurs algorithmes de traitement d'image ont été développés. Un programme d'inversion de perspective a été mis au point pour une utilisation en temps réel sur le terrain. Les caractéristiques des images peuvent être ensuite analysées. La première partie du mémoire comporte une description des différentes émissions lumineuses que l'on peut observer la nuit lorsque l'on regarde la voûte céleste. Ces émissions peuvent avoir deux origines: astronomique ou atmosphérique. Le problème de l'absorption atmosphérique et plus précisément les conditions requises pour de bonnes observations dans le domaine du proche infrarouge ont aussi été étudiées. Ensuite, la construction d'une station mobile de prise de vues est détaillée. Celle-ci doit permettre d'observer l'émission et d'obtenir des résultats exploitables par la suite. Trois méthodes d'observation ont été décrites: visuelle, photographique et à l'aide d'un détecteur CCD. La troisième, qui a été retenue, a été vue plus en détail. Le matériel utilisé, de la caméra à la plate-forme de prise de vues en passant par les objectifs et les filtres optiques, est ensuite décrit. Lorsque le matériel a été choisi, un protocole d'observation a été défini et mis au point. Le choix du site d'observation a été crucial. Plusieurs lieux géographiques ont été retenus et sont présentés dans le mémoire. Le déroulement d'une séance de prise de vue a été décrit afin de faciliter un futur programme d'observation. Deux séquences types d'observations ont été plus particulièrement détaillées: -la réalisation de panoramas permettant une étude des structures que fait apparaître l'émission, -la réalisation de séquences vidéos afin d'étudier la dynamique du phénomène. Dans une quatrième partie, je décris les méthodes de traitement des images qui ont été développées. Tout d'abord, des prétraitements sont appliqués aux images pour corriger les défauts (champ plat, offset,?). Ensuite, une méthode de restitution géographique permet d'obtenir une image plus exploitable de la couche émissive ; elle n'est alors plus observée à partir d'une station au sol, mais en employant une caméra virtuelle située à la verticale du site d'observation. Différents problèmes liés à cette méthode ont aussi été traités: réfraction atmosphérique proche de l'horizon, passage d'une surface atmosphérique à la surface du pixel correspondant, et effet de Van Rhijn. Plusieurs traitements ont été appliqués aux images pour faciliter leur exploitation: filtrage pour supprimer les objets parasites tels que les étoiles, amélioration du contraste, mise en évidence des structures par plusieurs méthodes. Les résultats de l'étude de ces structures sont ensuite exposés. La dernière partie du travail porte sur l'étude dynamique de l'émission. Tout d'abord, nous avons vu la variation globale de celle-ci au cours de la nuit, puis la dynamique des structures elles-mêmes ainsi que l'influence de cette émission sur les observations astronomiques. Des observations en collaboration avec l'équipe du lidar-Rayleigh de l'Observatoire de Haute-Provence ont permis d'établir une corrélation entre les variations de la densité des composés atmosphériques et les variations de l'intensité de l'émission étudiée. D'autres observations simultanées ont été effectuées avec une équipe située au Pic du Midi afin de réaliser une triangulation visant à déterminer avec précision l'altitude de la couche émissive. Les directions à suivre afin de continuer cette étude ont finalement été données. Les objectifs d'un tel programme consistant à obtenir une meilleure connaissance de la structure de la haute atmosphère terrestre et une amélioration des corrections des observations astronomiques en temps réel.

  9. Etude du comportement et de la modélisation viscoplastique du zircaloy 4recristallisé sous chargements monotones et cycliques uni et multiaxes

    NASA Astrophysics Data System (ADS)

    Delobelle, P.; Robinet, P.

    1994-08-01

    The results of experiment performed on a recrystallized zircaloy 4 alloy in the intermediate temperature domain 20 leqslant T leqslant 400 ^{circ}C are presented. To characterize the anisotropy, especially at 350 ^{circ}C, the tests were made under both monotonic and cyclic uni- and bidirectional loadings, i.e. tension-compression, tension-torsion and tension-internal pressure tests. The different anisotropy coefficients and especially R^p = \\varepsilon^p_{θθ} /\\varepsilon^ p _ {{^-_-}{^-_-} } seem to be temperature independent. An important feature of the behavior of this alloy in the neighbourhood of 300 ^{circ}C is attributed to the dislocations-point defects interactions (dynamic strain aging), phenomena often observed in the solid solutions. For the 2D cyclic non proportional loadings it is shown that a weak supplementary hardening appears, which is a function of the degree of the phase lag. We propose to particularize and to apply a unified viscoplastic model with internal variables to the considered alloy, as the model as already been developed and identified elsewhere for other isotropic materials. From a general point of view the introduction of the anisotropy in the model is made by four tensors of rank 4 ; [ M] is assigned to the flow directions, [ N] to the linear parts of the kinematical hardening variables and [ Q] , [ R] respectively to the dynamic and static recoveries of these tensorial variables. This phenomenological formulation leads to a correct representation of the set of the experimental results presented at 350 ^{circ}C, which provides an a posteriori confirmation of the formalism used. On étudie, entre 20 et 400 ^{circ}C, à l'aide d'essais sous chargements multiaxiaux monotones et cycliques (traction, torsion et pression interne) les propriétés viscoplastiques anisotropes de tube de zircaloy 4 recristallisé. A la température de 350 ^{circ}C, l'anisotropie a été quantifiée de façon détaillée. Les quelques résultats obtenus à la température ambiante ainsi que l'indépendance du rapport R^p = \\varepsilon^p_{θθ}/\\varepsilon^ p_{{^-_-}{^-_-} } avec la température laissent supposer que l'ensemble des coefficients d'anisotropie ne dépendent pas de la température. Par contre, la fluidité de cet alliage présente un minimum très marqué au voisinage de 300 ^{circ}C. Ce comportement est imputable au vieillissement dynamique fréquemment observé dans les solutions solides d'insertion. Lors d'un chargement cyclique hors phase (traction-torsion déphasée à 90^{circ}) ce matériau présente un léger durcissement supplémentaire. On propose l'extension au cas du zircaloy 4 de la formulation d'un modèle viscoplastique unifié développé et identifié par ailleurs sur d'autres matériaux initialement isotropes. D'une manière générale, l'introduction de l'anisotropie dans ce modèle s'effectue par l'intermédiaire de quatre tenseurs d'ordre 4 affectant les directions d'écoulement [ M] , les parties linéaires des écrouissages cinématiques [ N] , ainsi que les restaurations dynamiques [ Q] et statiques [ R] de ces mêmes variables d'écrouissage. L'identification de ce modèle est discutée et réalisée à 350 ^{circ}C. On montre l'adéquation du formalisme à appréhender l'ensemble des caractéristiques mécaniques de cet alliage.

  10. Champs morphogenetiques mis en evidence par l'etude au microscope electronique a balayage des soies au niveau des pattes d'abeilles (apoidea, megachilidae).

    PubMed

    Pasteels, J M; Pasteels, J J

    1973-01-01

    The hairs covering the legs of several species of female megachilid bees are arranged in imbricated fields. At the boundaries of these fields, either the hairs show a morphology intermediate between those of the contiguous fields, or there is a narrow strip with an irregular mosaïc of several hair types. It is suggested that: 1. The structure of the hairs may be determined by the territory in which the trichogenous cell is located. 2. Some morphogenetic fields are bidimensional and cross the segmentary boundaries. The name 'regional fields' is proposed for them. 3. The regional fields may be modulated within each segment into which they extend.

  11. European Gene Mapping Project (EUROGEM): breakpoint panels for human chromosomes based on the CEPH reference families. Centre d'Etude du Polymorphisme Humain.

    PubMed

    Cox, S A; Attwood, J; Bryant, S P; Bains, R; Povey, S; Rebello, M; Kapsetaki, M; Moschonas, N K; Grzeschik, K H; Otto, M; Dixon, M; Sudworth, H E; Kooy, R F; Wright, A; Teague, P; Terrenato, L; Vergnaud, G; Monfouilloux, S; Weissenbach, J; Alibert, O; Dib, C; Fauré, S; Bakker, E; Pearson, N M; Spurr, N K

    1996-11-01

    Meiotic breakpoint panels for human chromosomes 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 17, 18, 20 and X were constructed from genotypes from the CEPH reference families. Each recombinant chromosome included has a breakpoint well-supported with reference to defined quantitative criteria. The panels were constructed at both a low-resolution, useful for a first-pass localization, and high-resolution, for a more precise placement. The availability of such panels will reduce the number of genotyping experiments necessary to order new polymorphisms with respect to existing genetic markers. This paper shows only a representative sample of the breakpoints detected. The complete data are available on the World Wide Web (URL http:/(/)www.icnet.uk/axp/hgr/eurogem++ +/HTML/data.html) or by anonymous ftp (ftp.gene.ucl.ac.uk in/pub/eurogem/maps/breakpoints).

  12. Etude structurale et vibrationnelle d’un nouveau composé complexe de cobalt: [Co(imidazole)4Cl]Cl

    PubMed Central

    Derbel, Amira; Mhiri, Tahar; Graia, Mohsen

    2015-01-01

    In the title complex, chlorido­tetra­kis­(1H-imidazole-κN 3)cobalt(II) chloride, [CoCl(C3H4N2)4]Cl, the CoII cation has a distorted square-pyramidal coordination environment. It is coordinated by four N atoms of four imidazole (Im) groups in the basal plane, and by a Cl atom in the apical position. It is isostructural with [Cu(Im)4Cl]Cl [Morzyk-Ociepa et al. (2012 ▸). J. Mol. Struct. 1028, 49–56] and [Cu(Im)4Br]Br [Hossaini Sadr et al. (2004 ▸). Acta Cryst. E60, m1324–m1326]. In the crystal, the [CoCl(C3H4N2)4]+ cations and Cl− anions are linked via N—H⋯Cl hydrogen bonds, forming layers parallel to (010). These layers are linked via C—H⋯Cl hydrogen bonds and C—H⋯π and π–π [inter-centroid distance = 3.794 (2) Å] inter­actions, forming a three-dimensional framework. The IR spectrum shows vibrational bands typical for imidazol groups. The monoclinic unit cell of the title compound emulates an ortho­rhom­bic cell as its β angle is close to 90°. The crystal is twinned, with the refined ratio of twin components being 0.569 (1):0.431 (1). PMID:26594402

  13. Modelisation de la dependance de l'espace et du temps dans les etudes d' environnementModelamiento de la dependencia espacial y temporal en estudios ambientales

    NASA Astrophysics Data System (ADS)

    Stein, Alfred; Sterk, Geert

    This paper analyzes the use of stratification in the modeling of dependence for regionalized variables in space and time. Stratification enables optimal use of available information, and it is used when deterministic, small-scale information is combined with large-scale random variation: on the one hand, the problem of having too few data to reliably estimate statistical parameters may be solved by stratification; on the other hand some variation may be so obvious that it serves as a prerequisite for obtaining any form of stationarity. The paper is illustrated with four case-studies. The first study analyzes optimization of an extant groundwater monitoring network within a catchment of the river Rhine. Stratification in space enabled 5 cm precision of predicted levels at critical locations, something that could not be reached without stratification. The second study analyzed variability in space and time of wind erosion in a field. Erosion by four storms was measured with 21 devices. Use of temporal stratification to overcome lack of spatial data resulted, in one instance, in a decrease of 17 percent in mean absolute error. The third study addressed changes in the soil solution influenced by environmental deposition over a period of six years. Stratification was made in space to enable analysis in the time domain and to obtain spatio-temporal maps. The fourth study used a general space-time model to evaluate the development of root-rot in soybean, caused by naturally occurring pathogens. Predictions were made at unvisited times to estimate the probability of occurrence of root rot. We conclude that use of stratification enhances the utility of space-time statistics for the solution of various environmental and agricultural problems.

  14. [Long-term clinical tolerance of antihypertensive treatment during the HOT study. Groupe français de l'etude HOT].

    PubMed

    Mallion, J M; Dahan, R; Boutelant, S; Benkritly, A; Baguet, J P; Noir-Clerc, M

    1997-08-01

    The objective of the HOT study, an international, prospective, randomised study is to determine the optimal level of the blood pressure under treatment, in linked with the lowest cardiovascular mortality and morbidity. The target diastolic blood pressure of 80, 85 and 90 mmHg was determined at the randomisation. In order to reach the target blood pressure, a strategy of treatment was determined: the 1st step was felodipine (a long acting dihydropyridine) and the next steps (if the blood pressure reduction is not enough) propose the addition of different therapeutic classes and/or the increase of each drug doses. The available data after 2 years of the patients follow-up allow us to evaluate the incidence of the reported side effects according to the target blood pressure assigned by randomisation and the number of hypertension drugs used to reach these targets. The percentage of patients with at least one side effect at 12 and 24 months of follow-up are respectively: for the target group DBP < or = 90 mmHg: 9.2% versus 6%; for the target group DBP < or = 85 mmHg: 8% versus 4.4%; for the target group DBP < or = 80 mmHg: 7.9% versus 4.9%. The overall tolerability is not influenced by the target diastolic blood pressure but depends on the number of hypertension drugs used. At 24 months, 2.8% of patients are under monotherapy; 7% under bitherapy and 9.8% under tritherapy. The incidence of the side effects decreases after the 1st year, but slower than between the third months and the first year. There is an influence of the region on the incidence of the side effects, the south European countries describing more side effects than France or the north European countries. This seems to be linked with a perception of the side effects more than with a higher rate. In conclusion, these results confirm the possibility to reach a targeted blood pressure using a predetermined strategy without increasing dramatically the incidence of the side effects.

  15. Etude longitudinale de la névralgie cervico-brachiale dans le service de neurologie du CHU Gabriel Touré, Bamako (Mali)

    PubMed Central

    Maiga, Youssoufa; Fara, Amina Ahmed; Sogoba, Youssouf; Diango, Djibo; Diakite, Sara; Diallo, Mohamed; Ak, Hadiza; Diallo, Gangaly; Traore, Hamar Alassane

    2013-01-01

    Introduction La Névralgie Cervico-Brachiale (NCB) est une pathologie relativement fréquente dans la pratique courante. Elle est pourvoyeuse d'importants coûts médicaux et socio-économiques. Peu de données existent sur la NCB en Afrique. Méthodes Il s'agit d'une étude longitudinale, descriptive et prospective qui s'est déroulée du 1er novembre 2009 au 30 Août 2010 au CHU Gabriel Touré de Bamako, Mali. Elle a pour objectif d’étudier les caractéristiques épidémiologiques et cliniques de la NCB. Le diagnostic à été strictement clinique, et la DN4 a permis de déterminer les caractéristiques de cette névralgie. L'intensité de la douleur a été évaluée par l’échelle verbale simple (EVS). L’échelle concis de la douleur et l’échelle HAD ont permis d’étudier l'impact de la douleur sur la qualité de vie des patients. Résultats La fréquence de la NCB est de 10,9%. Les ménagères sont les plus touchées, 21(40,4%). L’âge moyen des patients est de 48 ±7 ans. La tranche d’âge de 50-59 ans représente la classe modale. La douleur est à prédominance nocturne chez 75,0% des patients. Les décharges électriques sont la caractéristique principale soit 48,1% des patients et 57,7% malades présentent une douleur intense. Sur le plan topographique, la racine C7, est la plus atteinte soit 50,0%. Sur la qualité de la vie, 44,2% des malades présentent des troubles du sommeil. Sur le plan thérapeutique l’évolution a été favorable chez 78,8% des patients sous AINS, Tramadol et Amitriptilline. Conclusion otre travail à l'instar des études antérieures sur la NCB montre que cette pathologie reste une entité clinique relativement courante. Le pronostic généralement favorable est fonction d'un diagnostic précoce et d'une prise en charge adaptée. PMID:24648859

  16. Etude de la qualité bactériologique de l’eau utilisée dans l’industrie agroalimentaire dans le Nord du Maroc

    PubMed Central

    Haijoubi, El Houcine; Benyahya, Fatiha; Bendahou, Abdrezzak; Essadqui, Faima Zahra; Behhari, Mohammed El; El Mamoune, Ahmed Fouad; Ghailani, Naima Nourouti; Mechita, Mohcine Bennani; Barakat, Amina

    2017-01-01

    Introduction L'eau est utilisée d'une façon primordiale dans tout le processus de la fabrication des produits alimentaires. Les industries agroalimentaires du Nord du Maroc utilisent différentes sources d'eaux mais l'eau de réseau public et l'eau de puits sont les principales sources d'eau utilisée. Cette eau peut s'avérer la source principale des éventuelles contaminations et altérations des aliments. Notre but est d'évaluer la qualité bactériologique de l'eau utilisée par les industries agroalimentaires dans la région du Nord du Maroc, d'identifier les différents germes responsables de la pollution de ces eaux et de définir les principales causes de cette pollution. Méthodes Des échantillons d'eau prélevés aux robinets ou des puits ont été analysés pour la recherche des germes indicateurs de la pollution (coliformes totaux (CT), coliformes fécaux (CF), entérocoques intestinaux (E), microorganismes revivifiables (MOR), anaérobies sulfitoréducteurs) et les germes pathogènes (Salmonelles, Staphylocoques, Pseudomonas aeruginosa). Le dénombrement des bactéries a été fait par la technique de filtration et par incorporation en milieu solide en surfusion. Résultats Les résultats ont montré que les eaux du réseau public ont été de qualité bactériologique satisfaisante tandis que 40% des eaux des puits ont été non conformes aux normes à cause de la présence des indicateurs de pollution CT, CF, E et MOR. En revanche, les germes pathogènes, en particulier les Salmonelles, ont été absents dans les eaux de tous les puits analysés. Conclusion La pollution de ces puits a été généralement liée au non-respect des conditions de puisage hygiéniques. La qualité bactériologique des eaux de ces puits peut être améliorée par une protection adéquate. PMID:28450992

  17. Investigation of Button Size and Spacing for Underwater Controls (Etude sur la Taille et L’Espacement des Boutons de Commandes Utilisees dans des Activites Sous-Marines)

    DTIC Science & Technology

    2008-04-01

    ergonomic design improvements. It is concluded that keypads designed for use in air are not optimal for use underwater. Résumé La présente étude...impractical without ergonomic design improvements. It is concluded that keypads designed for use in air are not optimal for use underwater. This...subject’s hands were immersed in a 4 water filled glass tank (0.3 m width x 0.9 m length x 0.3 m depth). The subject was seated on a high stool and

  18. Model Study of a Proposed Engineering Acoustic Research Facility (Etude sur Modele d’un Projet d’Installation de Recherches en Genie Acoustique)

    DTIC Science & Technology

    1976-07-01

    Toronto E.H. Dudgeon, Head/Chef D.C. MacPhail ,Engine Laboratory/ Laboratoire des moteurs Director/Directeur GO O/L/ D~~~~~~r1ISTRIBUT1I...acceptable et une faible sensibilit A la deviation du jet ont W ddfinies, mais ces dispositifs n’ont &6 rgalisds qu’au detriment du rendement

  19. Etude experimentale de la photoexcitation des colorants de type anthracene, azobenzene et thioindigo dans des matrices de cristaux liquides nematiques et smectiques

    NASA Astrophysics Data System (ADS)

    Saad, Bendaoud

    Nous avons étudié le comportement de différents colorants (tétracène et azobenzènes AZD3, DR1 et D2) dans des matrices de cristaux liquides (E7 et 5CB). Les résultats obtenus ont montré que la réorientation optique des molécules de cristaux liquides se produit à des intensités extrêmement faibles (~1 μW/cm 2). Nous avons attribué cet effet à l'interaction entre les molécules des colorants photoexcitées et celles des cristaux liquides hôtes. Ces interactions se produisent lorsque les molécules dichroïques exçitées transitent entre des états triplets intermédiaires tout en conduisant à la génération d'un nouveau moment optique géant, responsable de la réorientation des molécules. Le changement de la forme de la molécule du colorant, dû à l'isomérisation Trans-Cis , est à l'origine de la création de ce moment. Ce qui distingue notre réorientation moléculaire de celle obtenue sur d'autres systèmes hôtes-dopants est que les molécules sont repoussées du champ électrique de la lumière. Par ailleurs, cette réorientation est accompagnée d'une diffusion anisotrope des molécules excitées. Nous avons aussi étudié le cristal liquide PhBz rendu ferroélectrique en le dopant par des molécules thioindigos. En exploitant l'augmentation de la polarisation spontanée due à la photoisomérisation du colorant, nous avons pu réaliser un hologramme dynamique contrôlable par un champ optique assisté par une tension statique.

  20. Les enfants et "leurs peres" dans les familles recomposees: Une etude clinique (Infants and Their Fathers in Recomposed Families: A Clinical Study).

    ERIC Educational Resources Information Center

    Hurstel, Francoise

    1994-01-01

    Studied families formed by divorced parents who remarried. Describes the features, the fragility of social and legal status, difficulties in establishing family links, and the role of a newborn child in such families. (BC)

  1. Identification d'indicateurs de risque des populations victimes de conflits par imagerie satellitaire. Etude de cas: Le nord de l'Irak

    NASA Astrophysics Data System (ADS)

    Mubareka, Sarah Betoul

    Remote sensing and security, terms which are not usually associated, have found a common platform this decade with the conjuring of the GMOSS network (Global Monitoring for Security and Stability), whose mandate is to discover new applications for satellite-derived imagery to security issues. This study focuses on human security, concentrating on the characterisation of vulnerable areas to conflict. A time-series of satellite imagery taken from Landsat sensors from 1987 to 2001 and the SRTM mission imagery are used for this purpose over a site in northern Iraq. Human security issues include the exposure to any type of hazard. The region of study is first characterised in order to understand which hazards are and were present in the past for the region of study. The principal hazard for the region of study is armed conflict and the relative field data was analysed to determine the links between geographical indicators and vulnerable areas. This is done through historical research and the study of open-sourced information about disease outbreaks; the movements of refugees and the internally displaced; and humanitarian aid and security issues. These open sources offer information which are not always consistent, objective, or normalized and are therefore difficult to quantify. A method for the rapid mapping and graphing and subsequent analysis of the situation in a region where limited information is available is developed. This information is coupled with population numbers to create a "risk map": A disaggregated matrix of areas most at risk during conflict situations. The results show that describing the risk factor for a population to the hazard conflict depends on three complex indicators: Population density, remoteness and economic diversity. Each of these complex indicators is then derived from Landsat and SRTM imagery and a satellite-driven model is formulated. This model based on satellite imagery is applied to the study site for a temporal study. The output are three 90 m x 90 m resolution grids which describe, at a pixel level, the risk level within the region for each of the dates studies, and the changes which occur in northern Iraq as the result of the Anfal Campaigns. Results show that satellite imagery, with a minimum of processing, can yield indicators for characterising risk in a region. Although by no means a replacement for field data, this technological source, in the absence of local knowledge, can provide users with a starting point in understanding which areas are most at risk within a region. If this data is coupled with open sourced information such as political and cultural discrimination, economy and agricultural practices, a fairly accurate risk map can be generated in the absence of field data. Keywords. SRTM, Landsat, risk indicators, Iraq, conflict, population vulnerability, segmentation, land-use, fuzzy-classification, atmospheric corrections.

  2. The Relationship between Musical Instrumental Performance Skills and Postsecondary Musical Independence (How Important Are Scales, Etudes, Solos, Sight-Reading, Improvisation, Etc.?)

    ERIC Educational Resources Information Center

    Bobbett, Gordon C.; And Others

    This study examines the relationships among a variety of secondary/postsecondary experiences and activities and postsecondary students' musical independence (MI). The paper reports on the impact Instrumental Performance Skills (IPSs) have on the students" MI development during private lessons, band rehearsal, and individual practicing. The study…

  3. Etude structurale par RMN 29Si—V. Dérivés de la quinoléine et de l'isoquinoléine

    NASA Astrophysics Data System (ADS)

    Grignon-Dubois, M.; Fialeix, M.; Laguerre, M.

    A series of silylated compounds obtained from quinoline or isoquinoline were studied by 29Si NMR using the selective polarization transfer (SPT). Both silicon chemical shifts and 29Si, 1H coupling constants have been measured. These results are the first example of coupling through siliconnitrogen bonds.

  4. Etude de phenomenes cinetiques a longue portee lors de la croissance epitaxiale a l'aide de la methode Monte Carlo cinetique

    NASA Astrophysics Data System (ADS)

    Beausoleil, Alexandre

    The main objective of this thesis is to study long range kinetic phenomena during epitaxial growth with the kinetic Monte Carlo (KMC) method. We begin by studying the impact of long jumps and the reversible aggregation regime on singular surface growth. We then present an alternative KMC method which allows to decrease the simulation time. With this new method, we finally analyze the impact of nucleation on vicinal surface growth. In a study on the impact of the reversible aggregation regime combined to the Meyer-Neldel rule on submonolayer epitaxial growth, we observe that atom and small island densities are such that the island size distribution is bimodal. The frequent detachment events are responsible for an increase of the number of unattached atoms and the probability of nucleation increases due to this large density of atoms, resulting in an important small island density. In such a case, those small islands are metastable because of their large probability to fragment following a detachment event. Long jumps accentuate the distinction between the two modes of the bimodal island size distribution by allowing detached atoms to diffuse far away from islands. Long jumps increase the effective diffusion coefficient of atoms, which show a supra-Arrhenius behavior especially important for a large maximum long jump extent. Since the most frequent events in our simulations are simple diffusion events (that is, when an atom is not attached to an island), which account for nearly 80% of the number of performed events, we develop an improved KMC method which allows to reduce the simulation time for such events. To do so, we partition the atoms in two groups, the first one containing the atoms far enough from each other to be considered interaction free (with respect to the KMC model used) and the other one containing all bonded atoms. This non-interacting condition allows to reduce the number of updates required after the diffusion of an atom without any additional approximation compared to the KMC method. This strategy results in the elaboration of a new method, the LAUKMC (for low adatom update KMC) method. The LAUKMC simulations are approximatively four times faster than equivalent KMC simulation in a step flow regime, and six times faster when the reattachment procedure is applied. The speed-up is especially important when the number of atoms out of interaction range from other atoms is large and when the aggregation regime is strongly reversible. For limited diffusion and irreversible aggregation regime conditions, the LAUKMC method behaves as KMC simulations and little speed-up is observed. Nucleation lengths of first ( Ln ) and second ( Ln2 ) layers allow to elaborate a phase diagram that describes the transition from a step flow to a three-dimensional layer-by-layer island growth regime which occurs through two-dimensional island growth. By comparing the terrace width (W) with the nucleation lengths on the phase diagram, we can predict that when W < Ln , the Bales-Zangwill and kink-Ehrlich-Schwoebel-effect meandering instabilities will manifest since the growth regime is one of step flow. From LAUKMC simulations, we predict a new mechanism leading to the apparition of meanders of step edges of vicinal surfaces. This instability appears when W ≃ Ln

  5. etude experimentale de la propagation de fissures de fatigue dans la zone affectee thermiquement de joints soudes de roues de turbines hydrauliques

    NASA Astrophysics Data System (ADS)

    Trudel, Alexandre

    This thesis presents the results of a comprehensive experimental study on the fatigue crack propagation behavior in aqueous environment of the heat affected zone of CA6NM stainless steel hydraulic turbine runner welds. The initial objective of this project was to determine the fatigue crack growth properties of the heat affected zone. To achieve this, standardized fatigue crack growth tests in aqueous environment were performed to determine the crack growth threshold DeltaKth, and the Paris relationship constants C and m of the heat affected zone. Given potential experimental uncertainties arising from the growth of a crack confined to the heat affected zone, fatigue crack growth tests in an aqueous environment at constant stress intensity factor range (DeltaK) were performed so that the crack would propagate across the heat affected zone. These tests allowed to better appreciate the fatigue crack growth resistance variation between the three zones of the weld, i.e., the filler metal, the heat affected zone and the base metal. Various experimental objectives were supplemented to these two primary objectives. A CA6NM plate was welded to generate a layer of filler metal over its entire surface. The welded plate was cut in two equal pieces, one of which was post-weld heat treated in order to study the effect of this treatment on the fatigue crack growth behavior. Compact tension type fatigue specimens were machined from the welded plates. Rectangular samples were also collected to allow the characterization of the weld. Metallographic observations and X-ray diffraction measurements of the three zones of the weld (filler metal, heat affected zone and base metal) were conducted in order to characterize the microstructure. This microstructural characterization combined with metallographic observations of the crack path profiles were useful in assessing the microstructural effects acting on the fatigue crack growth behavior of the weld. Microhardness measurements were carried out across the weld in order to quantify the heat affected zone width and to allow a relative mechanical characterization of the three weld zones. Residual stresses were measured in fatigue specimens to determine their influence on the fatigue crack growth behavior. Finally, the fracture surfaces were observed using a scanning electron microscope in order to identify the main fracture mechanisms. This work led to several conclusions about the fatigue crack growth behavior in aqueous environment of hydraulic turbine runner welds, and especially in the heat affected zone. First, the measured crack tip tensile residual stresses inhibited crack closure, which resulted in a deteriorated resistance to fatigue crack growth. On the other hand, the beneficial effect of post-weld heat treatment was explained by its ability to sufficiently reduce the tensile residual stresses to allow crack closure to occur. Secondly, the martensitic microstructure of the three weld zones was identified as influencing the fatigue crack growth behavior. The varying martensite coarseness between the three weld zones influenced the path of the crack. A fine martensitic microstructure, as observed in the weld metal, resulted in a linear crack path, while a coarse microstructure, as observed in the heat affected zone and base metal, resulted in a tortuous crack path. The degree of crack path tortuosity was related to the fatigue crack growth resistance, which revealed that a coarse martensitic microstructure that leads to a tortuous crack path, promotes toughening by local mixed modes of crack advance and roughness-induced crack closure. Thirdly, when the crack propagated in the heat affected zone, a tendency to gradually deviate towards the base metal was observed. This behavior was rationalized by considering the yield strength mismatch between the three weld zones. The yield strength decreased in the heat affected zone from filler metal to base metal. Finally, the presence of residual and/or reformed austenite in the three zones of the weld, as well as the occurrence of an intergranular fracture mechanism in the heat affected zone and base metal were identified as having a negligible influence on the fatigue crack growth behavior in the amounts measured. The main conclusion of this study is that the heat affected zone is only slightly less resistant to fatigue crack growth than the base metal. This was attributed to its somewhat finer microstructure that leads to a less tortuous crack path. It is rather the weld-induced residual stresses that dominantly affect the growth of fatigue cracks in hydraulic turbine runner welds. From a practical point of view, the results of this research allow to assert that the turbine runner welding process combined with a post-weld heat treatment produce a weld with good resistance to fatigue crack growth. (Abstract shortened by UMI.).

  6. Contribution de l'altimetrie satellitaire a l'etude de la variabilite du niveau d'eau du Delta interieur du fleuve Niger

    NASA Astrophysics Data System (ADS)

    Telly Diepkile, Adama

    Title: Contribution of satellite altimetry to the study of the spatial and temporal variability of water level in the Inner Delta of Niger River Content: The radar altimeter was originally developed to contribute to the study of ocean waters dynamics. The large size of oceans and their relative homogeneity favor the use of satellite altimetry. The success on the oceans led many researchers to investigate the use of satellite altimetry for the characterization of inland waters and land surfaces. Encouraging results have been reported by some studies on the hydrology of inland seas, lakes and rivers and floodplains. In this thesis, we evaluate the contribution of satellite altimetry in the analysis of changes in water level in the Inner Delta of Niger River in Mali, in West Africa. Classified among the sites of the Ramsar Convention on Wetlands, the Inner Delta plays a leading role for Mali and the whole sub-region, both on the socio-economic and environmental scales. The Delta is characterized by a flooding period, during which an area of over 20,000 km2 of land is flooded. The water withdraws completely during the recession. These dynamic flooding-recession conditions practically control all the human activities in the region and significantly influence the ecological processes. On the other hand, the Delta is becoming more and more fragile due to desertification, climate change and agricultural activities. A better characterization of water level variations and understanding the hydrological regime are of critical importance in the Delta. Satellite altimetry data considered in the study come from Topex/Poseidon (1992-2005) and Envisat (2002-2009). The data were corrected for environmental effects. In order to develop time series including data from both satellites, we analyzed their overlapping period (2002-2005). This analysis revealed a good correlation between the two sets of measurements (R2 = 0,76), and a systematic bias of about 89 cm. The Envisat measurements were then corrected to bring them in the same altimetry reference level as Topex/Poseidon, thereby producing time series of 17 years (1992-2009). Following this analysis, we proposed a waveform retracking algorithm that integrates the backscattering coefficient to the time scale of penetration of the radar pulse in a medium with a presence of vegetation. The idea here is to consider the heterogeneity of a medium such as the Delta, which can be covered with vegetation. For this, we introduce into the equation of the waveform, the backscattering coefficient estimated from the so called water cloud model, to create a new algorithm called retracking algorithm of water cloud. This algorithm was applied to the Envisat and OSTM/Jason-2 data. The results of the algorithm were validated with in situ measurements of the Direction Nationale de l'Hydraulique du Mali and also with measurements acquired during a campaign of data collection conducted between August and October 2009. The observed differences are generally small (<+/- 1 m). The retracking algorithm of water cloud was compared to other existing algorithms. It shows a strong correlation with Ice-1 (R 2 = 0,84). Finally, we analyzed the influence of precipitation on the variations of the altimetry-derived water levels. Three sources of precipitations from satellite measurements and reanalysis data were considered in three catchments (basin Fouta Djallon in upstream, Bani basin and the inner basin in Mali). The analysis reveals the importance of precipitations, particularly in the basin of Fouta Djallon. Approximately 70% of sites analyzed in the Delta show a relatively strong correlation (R2 > 0,40) with the cumulative precipitations in the basins considered. Keywords : Remote Sensing, Satellite altimetry, Continental waters, Water level, Long term analysis, Inner Delta of Niger River, Water-cloud model, Envisat, Topex/Poseidon.

  7. Contribution a l'etude des mecanismes de l'adhesion de la glace a differents materiaux et application a l'evaluation des materiaux glaciophobes

    NASA Astrophysics Data System (ADS)

    Ghalmi, Zahira

    Several Nordic countries with cold climates like Canada are often subjected to ice storms causing major economic and social losses. Ice or sticky snow adhesion on power network equipment can be a significant issue in transmission and distribution of electrical energy for companies operating in these regions. The costs of such events can be substantial, particularly due to the cessation of economic activities, equipment failures, deicing techniques (active methods), and population safety. Because of such events, power companies have understood the need to develop so-called superhydrophobic and/or icephobic surfaces, which can significantly reduce ice adhesion (passive methods). Several studies have led to the development of a variety of new nanostructured surfaces using various strategies. These studies have led to the design of superhydrophobic surfaces with contact angles greater than 150 and low ice adhesion strength. In order to optimally reduce the ice adhesion strength on different substrates, better understanding of the various mechanisms involved in the icing process is essential. It is in this context and within the framework of Canada's research chair on atmospheric icing of power networks (INGIVRE) that this thesis was carried out, aiming to improve the knowledge of atmospheric icing, and explain the forces involved at the ice/substrate interface. Furthermore, the effect of contact angle, surface roughness and porosity on icing and ice/substrate interface was investigated. This study clearly showed that the electrostatic, van der Waals and hydrogen bond forces are the main contributors to ice adhesion to a surface at the molecular level. The electrostatic energy, based on the principle of image charge, depends on the type of material in contact with the ice, the distance between the ice and the material, and the types of ice surface defects. The van der Waals energy depends on the material type, the thickness of the liquid water layer, and the temperature. For its part, the energy associated with hydrogen bonds depends on the material type, temperature, droplet mass, as well as on the static and sliding contact angles. Among these three forces, the electrostatic energy is the largest. Whereas the hydrogen bond energy is larger than the van der Waals energy. However, the latter is always present as long as ice is in contact with a solid surface. The experimental study showed that ice adhesion strength depends on the surface roughness of the substrate. In the case of metals with a thin natural protective oxide layer, higher roughness leads to higher ice adhesion strength. In other words, polished metallic surfaces exhibit lower ice adhesion strengths. However, in the case of anodized aluminum surfaces coated with PTFE, the roughened needle-like structure resulted in lower ice adhesion. The experimental results showed that PTFE coatings remain resistant to icing/deicing cycles. Even after 15 icing/deicing cycles, surfaces remain hydrophobic with a static contact angle greater than 130°.

  8. Contribution a l'etude du comportement de dalles de ponts en beton arme de barres en PRF soumises a des charges concentrees simulant les charges de roues

    NASA Astrophysics Data System (ADS)

    Bouguerra, Kheireddine

    Au cours des dernieres annees, la deterioration des structures en beton arme a pris une ampleur sans precedent, et ce, malgre le fait que leur duree de vie en service initialement prevue est loin d'etre atteinte. La corrosion de l'armature d'acier est un des principaux facteurs reduisant la duree de vie des ponts en beton arme d'acier. Par ailleurs, l'armature en materiaux composites de polymeres renforces de fibres (PRF) constitue une solution a l'armature metallique afin de pallier au probleme de la corrosion d'acier et a la deterioration des structures en beton arme. Aussi, les barres d'armature en materiaux composites de PRF possedent une resistance en traction elevee (environ 2 a 6 fois la limite elastique de l'acier d'armature conventionnel), ce qui leur permet de constituer un renforcement structural attrayant pour les structures en beton. Le comportement d'elements structuraux en beton arme de barres en PRF est different de ceux en beton arme de barres d'acier. En effet, les barres en PRF possedent un module d'elasticite relativement plus faible que celui de l'acier et ont des proprietes d'adherence differentes de celles des barres d'acier. L'utilisation des barres d'armature en PRF pour armer les dalles de tabliers de ponts se concretise de plus en plus avec l'avancement des recherches dans ce domaine. La recherche entamee dans le cadre de cette these s'inscrit dans un programme de travaux realises au sein de la Chaire de recherche CRSNG/Industrie sur les Materiaux composites novateurs en PRF pour les infrastructures au departement de genie civil a l'Universite de Sherbrooke. Le comportement de membrures en beton arme de PRF soumis a des sollicitations mecaniques constitue un des principaux axes de recherche. Dans le cadre de cette these, une serie d'essais a ete effectuee sur huit dalles de ponts a confinement interne a grande echelle. Les parametres des essais comprennent: (1) l'epaisseur de la dalle, (2) le type et le taux d'armature transversale de l'assemblage inferieur, (3) la resistance en compression du beton, et (4) le taux d'armature dans les autres directions (armatures transversale et longitudinale de l'assemblage superieur et l'armature longitudinale de l'assemblage inferieur). Lors des essais de chargement, les dalles ont ete supportees par deux poutrelles metalliques espacees de 2000 mm centre a centre et soumises a une charge statique concentree sur une aire de contact de 600 mm x 250 mm afin de simuler une charge de camion (87,5 kN--CL-625) et ce conformement au code Canadien sur le calcul des ponts routiers [CAN/CSA-S6-06]. Aussi, une analyse numerique du comportement des dalles testees sous charges est faite a l'aide d'un logiciel d'elements finis ADINA version 8.2. Les essais ont montre que toutes les dalles testees ont rompu par poinconnement, peu importe le parametre etudie. Aussi, une epaisseur de dalle de 175 mm repond aux exigences du Canadien sur le calcul des ponts routiers [CAN/CSA-S6-06]. Par ailleurs, les resultats ont montre que la resistance en compression du beton est un parametre qui influe sur la deflexion, les deformations dans les barres et l'ouverture de fissures. Enfin, les resultats des analyses numeriques effectuees corroborent avec ceux obtenus experimentalement. Mots cles. Dalle de ponts en beton, armature de PRF, charges statiques, flexion, deformations, poinconnement, elements finis.

  9. Etude de la Morphologie et de la Cinématique de l'Emission des Raies interdites autour des Etoiles T Tauri

    NASA Astrophysics Data System (ADS)

    Lavalley, Claudia

    2000-06-01

    Le phénomène de perte de masse joue un rôle essentiel dès les premières étapes de la formation stellaire et semble être intimement lié à l'accrétion de matière sur l'étoile, probablement par l'intermédiaire de champs magnétiques permettant de convertir l'énergie cinétique accrétée, en puissance d'éjection. Les étoiles T Tauri classiques, âgées de quelques millions d'années et présentant une faible extinction, offrent un excellent cadre pour étudier les régions internes des vents stellaires. Dans ce travail, je présente les premières études sur la morphologie des jets associés aux étoiles DG Tau, CW Tau et RW Aur à une résolution angulaire de 0.1'' et sur la cinématique à deux dimensions de l'émission des raies de [O I]?6300Å, [N II]?6583Å et [S II] ?6716,6731Å dans le jet de DG Tau. Ces données ont été obtenues avec deux techniques d'observation complètement nouvelles, devenues disponibles entre 1994 et 1998 au télescope CFH, et idéalement adaptées à ce problème: l'imagerie en bande étroite derrière l'optique adaptative (PUEO) qui fournit des données à très haute résolution angulaire (~0.1''), et la spectro-imagerie intégrale de champ (TIGRE/OASIS) qui donne accès à l'information spatiale et spectrale à 2D, à haute résolution angulaire (ici ~0.5''-0.75'') et moyenne résolution spectrale (100-170 km/s). Les trois jets étudiés, résolus pour la première fois à partir de 55 u.a. de l'étoile, présentent une largeur similaire (30-35 u.a.) jusqu'à 100 u.a. et une morphologie dominée par des noeuds d'émission. Les jets des étoiles à faible excès infrarouge CW Tau et RW Aur sont très similaires aux deux autres jets des sources peu enfouies observés jusqu'à présent à la même échelle spatiale. Le jet de DG Tau, plus perturbé que les deux autres, et provenant d'une source avec une enveloppe encore importante, est aussi très similaire au seul autre jet associé à une source encore enfouie résolu à ces distances de l'étoile. Ceci donne des pistes sur l'évolution de l'interaction des jets avec l'environnement circumstellaire. La morphologie et la cinématique du jet de DG Tau suggèrent fortement une variabilité dans la vitesse d'éjection, qui pourrait aussi expliquer certains des noeuds des deux autres jets. La compatibilité d'un des noeuds observés avec les chocs en arc attendus dans une telle situation, a été bien mise en évidence. Des rapports de raies à différentes distances le long d'un jet (DG Tau) et à plusieurs intervalles de vitesses ont été obtenus ici pour la première fois. Des routines d'inversion considérant l'équilibre d'ionisation pour l'oxygène et l'azote et la fraction d'ionisation de l'hydrogène comme paramètre libre, ont permis de faire une estimation des variations de conditions d'excitation (Te, xe et ne) tout au long du jet. Une comparaison détaillée des rapports de raies observés avec les prédictions de différents modèles d'excitation, à l'aide de diagrammes rapport-rapport discriminants identifiés ici pour la première fois, favorise fortement la présence de chocs avec des vitesses de 50-100 km/s, à partir de 0.2'' de l'étoile.

  10. Developpement d'un catalyseur nickel-alumine efficace pour le reformage de diesel a la vapeur d'eau et etude du systeme reactionnel

    NASA Astrophysics Data System (ADS)

    Fauteux-Lefebvre, Clemence

    Le developpement de sources d'energie alternatives fiables et efficaces est aujourd'hui une necessite. L' interet dans le reformage d'hydrocarbures liquides est ainsi croissant puisqu'il s'agit d'une voie pour l'alimentation des piles a combustible. Les piles a combustible ont une efficacite pour la conversion d'energie en electricite plus grande que celle des moteurs a combustion et font ainsi partie de la recherche de solution en efficacite energetique. Ces piles consomment de l'hydrogene comme combustible pour produire de l'electricite, d'ou l'interet pour le reformage. En effet, cette reaction permet de produire de l'hydrogene et du monoxyde de carbone (un autre combustible des piles a combustible a electrolyte solide) a partir d'hydrocarbure liquide, notamment le diesel. Les piles pourraient donc etre integrees avec une unite de reformage leur fournissant directement le combustible necessaire a partir de diesel. Dans ce projet de recherche, un nouveau catalyseur de nickel sous forme de spinelle nickel-alumine (spinelle NiAl2O4 sur support d'alumine et de zircone stabilisee avec yttria) a ete developpe et teste en laboratoire pour du reformage de propane, d'hydrocarbures liquides et de diesel, a la vapeur d'eau. Par ailleurs, une methode d'ajout des reactifs novatrice a ete utilisee afin de diminuer la pyrolyse precedant le reformage, en utilisant une emulsion. Les resultats de reformage d'hydrocarbures purs ont montre des concentrations tres pres de l'equilibre thermodynamique et une activite constante sans desactivation du catalyseur ni formation de carbone, et ce avec des ratios H2O/C de moins de 2.5 et des temperatures d'operation variant entre 630 °C et 750 °C. Lors de tests effectues en utilisant du diesel fossile, a 705°C, avec un debit volumique des reactifs de plus de 50 000 cm3gcat-1h-1 et un ratio H2O/C de moins de 2.5, l'activite a ete maintenue pendant plus de 15 heures, malgre une operation en cycles. L'analyse du catalyseur apres cette utilisation n'a montre aucun carbone significatif sur la surface.- En comparaison, un catalyseur de nickel metallique sur support d'Al2O3 et YSZ a ete utilise dans des conditions similaires. Il y a eu desactivation du catalyseur et obstruction du reacteur par du carbone apres trois heures d'operation. L'analyse de ce catalyseur a permis de verifier qu'il etait recouvert de carbone en filament. L'analyse du systeme reactionnel a montre que la reaction est controlee par la reaction de. surface et non par le transfert de masse. Par ailleurs, les analyses des catalyseurs de spinelle ont demontre qu'il n'y avait pas de modification de sa forme chimique ni de reduction du spinelle en nickel metallique apres l'utilisation. Mots cles : Reformage a la vapeur, diesel, hydrocarbure liquide, catalyseur, spinelle nickel-alumine, equilibre thermodynamique

  11. Passage de la Langue Maternelle a la Langue Etrangere: Etude Experimentale (From the Native Language to the Foreign Language: An Experimental Study).

    ERIC Educational Resources Information Center

    Bourguignon, Christiane

    1979-01-01

    Reports on an experiment designed to test French secondary students' intuitive understanding of the nuances among six semantic categories of the structure "'etre' plus past participle," and their ability to translate these nuances into a second language (English or Spanish). (AM)

  12. Etude experimentale et optimisation d'un systeme hybride hydraulique pour camions a ordures et amelioration des performances par raffinement de sa logique de controle

    NASA Astrophysics Data System (ADS)

    Lacroix, Benoit

    The aim of this thesis is to demonstrate experimentally the operation of a hydraulic hybrid system specifically dedicated to the application of refuse trucks in addition to proposing solutions to improve its control strategy. The developed hybrid system recovers the vehicle's kinetic energy during braking. A variable displacement hydraulic motor then uses the energy stored in a hydraulic accumulator to assist the internal combustion engine (ICE) at suitable times. The particular aspect of this system is that assistance to the ICE can occur when it operates at idle and drives the auxiliary hydraulic equipment of the refuse truck. Essentially, the control strategy initially developed maximizes the recovery of braking energy and uses that energy to minimize the solicitation of the ICE at idle. The experimental results obtained with two prototypes tested in real operating conditions show that the hybrid system can recover a significant portion of braking energy. In addition, the results show that it is possible to reduce the load on the ICE during idle with the application of an assisting torque. However, the advantage of assisting the ICE in specific areas of the operating range is slim since the ICE's gross efficiency varies only slightly depending on conditions of operation. This is confirmed by the optimization of the control logic using deterministic dynamic programming. Indeed, by managing the pressure in the accumulator to maximize the amount of energy recovered during braking and by dosing the assistance to the ICE in an ideal fashion, the optimal control only managed to improve fuel savings by 6% in comparison to the original control. Therefore, since the efforts that would be required to emulate the ideal behavior in real time are significant for a relatively small and uncertain gain, the initial control logic is considered near optimal. Finally, this thesis proposes an improved version of the torque assisting hybrid system that could shut down the ICE when the vehicle is stopped while maintaining functional the auxiliary hydraulic equipment. An optimization of the control logic indicates that proper management of the pressure in the accumulator would allow turning off the ICE most of the time at stop and thus, would increase the fuel savings by over 40% compared to the original system. The simulation of a basic control strategy shows that such pressure management may be feasible in real time and that the potential gain in fuel savings is achievable. Keywords: hybrid system, hydraulic, control, refuse truck.

  13. Etude de faisabilite de l'insertion d'une membrane elastomere a renfort textile dans l'aspirateur d'une centrale hydroelectrique

    NASA Astrophysics Data System (ADS)

    Delorme, Rolland

    The generation of electrical energy in Quebec, estimated to 200 TWh, comes from hydroelectric generating stations for 96 % which are at the heart of provincial ecological and economic challenges. An important amount of research has been devoted to improving the hydrodynamic profile of hydraulic turbines to maximize their energy efficiency. However, few studies have focused on the draft tube in hydroelectric power plants, which is the duct where water flows out after crossing the turbine. Recent calculations performed by Alstom Power & Transport Canada Inc. revealed that the shape modulation of the draft tube could increase the hydroelectric generating station performance. The goal of this research was to assess the feasibility of this shape modification in existing draft tubes with inflatable composite membranes. The study consisted first of building an experimental setup to test the inflation of at membranes made up of a fiberglass-reinforced rubber composite. The inflated membranes were digitized with an optical equipment enabling 3D representations of their deflections. The second part of the study aimed at building finite element models reproducing the same experiments and enabling the design of more complicated membranes. The study confirmed the technical feasibility of designing and manufacturing such a membrane for the targeted application. However the large-scale roll-out will require to manufacture 3D membranes with the proper anchoring system. Keywords: reinforced rubber composite, reinforced elastomer composite, textile reinforcement, finite element modeling, mechanical behavior.

  14. Methodologie d'evaluation de la demande de chaleur des groupes de batiments dans le cadre d'une etude de faisabilite du chauffage urbain

    NASA Astrophysics Data System (ADS)

    Quirion-Blais, Olivier

    In the context of energy efficiency improvements to pulp and paper mills, process modifications allow to free low quality steam. This kind of low pressure and temperature steam is often found to be in excess in mills. New opportunities to use this energy could be created by gathering plants along with local communities and other enterprises into eco-industrial clusters. Following this proposition, district heating is an interesting technology that could be developed. It consists in supplying buildings with steam or hot water from one or more central heating plants through a series of canalization, generally underground. The supplied energy is used mostly for space heating but it can also be used with appliances specially designed for this purpose. Under certain conditions, this type of heating is cheaper and more environmentally friendly for several reasons including the facts that one central boiler plant is more efficient and has lower pollutant emissions due to better combustion control. Moreover, it can be adapted to multiple fuels that are locally available such as biomass around some pulp and paper mills. However, to insure that the savings occur, the heat demand must be sufficiently high and concentrated. Therefore, detailed feasibility studies shall be conducted to justify significant investments. Such studies require a lot of time not to mention that they necessitate a lot of data which can be difficult to obtain. The objective of this work is to develop a methodology that can assess the feasibility of district heating quickly and using easily accessible data. It was mainly designed to determine the heat consumption, which is especially critical as to decide whether or not to implement this technology. The focus is primarily directed on residential buildings, but another methodology is also developed to take into account the commercial and institutional buildings demand. An analysis of the sources of data revealed a certain redundancy among them. Therefore, four different computation procedures were developed to obtain the heat consumption of residential buildings: • C1, the first procedure, is the most time consuming one. It is also the one that uses the most specific information from the case: aerial photographs, census data (building year of construction and type (single family detached, single family attached, apartments or mobile homes)) and punctual on-site verification from the target area. National estimates of thermal requirements values are also used. • C2, the second procedure, is less specific than C1, but is much less time consuming to achieve. The local data sources used are: aerial photographs and census data from the case. While the national ones are: estimates of the building heating surfaces and thermal requirements. • C3 and C4, are the easiest procedures. Those two are very similar. The specific data used in these cases are census data from the locations under study. National data used for C3 are building surface estimates and thermal requirements values while C4 only uses thermal requirement values which are slightly different from those of C3. A further analysis revealed later that these two calculations yielded the same results. Therefore, since C3 is slightly more complicated to implement, it was removed from further analysis. Using three procedures thus ensures the stability of the methodology when the three results are the same order of magnitude. An average of the three results gives a good estimation of the consumption. The methodology was then applied to four study cases. One of them has already been the subject of a detailed district heating assessment feasibility study. It is used to validate the results obtained with the new methodology. The three other cases are rather used to test different conditions (number, density, type and year of construction of buildings). The validation results showed that the methodology can determine the heat consumption to about 20% of the baseline value. It also determines the total heating surface to about 5%. The three other study cases, A, B and C, have confirmed that possibility of applying the methodology in various conditions. Case A showed lower gaps between the four procedures when the rate of single family houses is lower. Since this rate is high in the validation case, better results can be expected for cases where the number of single family houses is low, such as in case A. In case B, the global results showed a particularly low gap between the four procedures with a maximum of 5%. However, an analysis of individual dissemination areas showed higher positive and negative gaps, which, when they are summed, compensate for the individual errors. The bigger errors in this case are explained by the fact that the apartments in this city are larger than the national average. Case C presented an additional challenge since no aerial photo was available. It has nevertheless been possible to realize two calculation procedures, C3 and C4, which provided a broad approximation of the consumption. For the commercial sector, a similar methodology to that of the residential sector is developed. However, the lack of global data has prescribed the individual processing of every building. This approach is also justified by the fact that commercial and institutional buildings are less numerous and have higher consumption. Due to the extended duration of this type of approach, only the validation and case Aare realized. The first one confirmed the better results than the ones from the residential sector with a gap of 7% compared to the consumption baseline. The results from case A showed the areas where the heat consumption is higher. Furthermore, it showed that the commercial and institutional demand accounts for 10% to 40% of the total heat demand. The integration of the results obtained into a district heating feasibility study is then discussed. A joint analysis of the residential and the commercial and institutional sectors showed the importance of considering each building's heat consumption for the planning of a district heating network. The profitability of the study cases is considered in relation to the thermal thresholds suggested in the literature.

  15. Patch test reactions to mite antigens: a GERDA multicentre study. Groupe d'Etudes et de Recherches en Dermato-Allergie.

    PubMed

    Castelain, M; Birnbaum, J; Castelain, P Y; Ducombs, G; Grosshans, E; Jelen, G; Lacroix, M; Meynadier, J; Mougeolle, J M; Lachapelle, J M

    1993-11-01

    We performed patch tests with Dermatophagoides pteronyssinus (Dp) antigens from 2 different sources in 355 non-randomly selected patients with atopic dermatitis (AD) and 398 subjects of a control group. The study demonstrated that contact sensitization to mites occurred in an appreciable % of AD cases (20.8%), using commonly available assay products. The differences recorded between the 2 materials tested were related to the concentration of P1 antigen. Non-atopic patients rarely showed positive reactions to Dp (0.75%), when strict criteria for readings were applied and if 2 readings were performed. Patients with positive patch tests did not necessarily show positive immediate skin tests. It would be useful to carry out tests systematically in atopic patients, even if it is not yet known what modern treatment would be best for the patient. Laboratories still do not provide standardized house dust mite preparations--measuring and codifying their biological activity--for use in patch tests. It is to be hoped that the extension of this type of test will lead to the production of better test materials, in syringes with homogeneous dispersion and concentration.

  16. La detection des cyanobacteries en milieu lacustre par l'etude des anomalies des spectres de reflectance de l'eau

    NASA Astrophysics Data System (ADS)

    Constantin, Gabriel

    Proliferation of cyanobacteria is a growing problem in lacustrine environment that results in rapid degradation of water quality. Moreover, certain cyanobacteria species produce harmful toxins. Phycocyanin (PC) is a photosynthetic pigment typical of cyanobacteria and affects the water color: it is therefore possible to study them using remote sensing. At least three algorithms to estimate PC concentration ([PC]) have been published, but their relative errors are important, especially for lower concentration. In this study, we are presenting the results of a new algorithm that uses the second order variability (anomalies) of water's reflectance spectrum to estimate [PC]. This method has never been used in lacustrine environment. The dataset used to develop and validate the algorithm was obtained between 2001 and 2005 in 57 different lakes and reservoirs of the Netherlands and Spain. The performance of the second order algorithm is equivalent or better than the three previously published algorithms. For the subset were [PC] > 32 mg m-3, the contribution of the second order term (R2=0.68 and RMSE=0.25) seems to improve considerably the first order algorithm (R2=0.50 and RMSE=0.35). The accuracy of the second order algorithm for [PC] > 32 mg m-3 is superior to the one calculated for the whole dataset (R2=0.69 and RMSE=0.44). The algorithm can also be adapted to the. bands of satellite sensor MERIS for the study of cyanobacteria. The application of this algorithm to a MERIS image acquired the 29 August 2010 taken over the Missisquoi Bay (Quebec, Canada) demonstrates the potential of this new algorithm for a future cyanobacteria' monitoring system. Note that all the statistical results presented above are for the logarithm of [PC] and the units of the RMSE are log(mg/m 3).

  17. Adult Literacy: Policies, Programs and Practices. Lessons Learned. Final Report = Alphabetisation des adultes: politiques, programmes et pratiques. Etude bilan. Rapport final.

    ERIC Educational Resources Information Center

    2001

    Studies and reports examining the problems associated with adult literacy and efforts to address those problems were reviewed to identify lessons for adult literacy programs in Canada and elsewhere. Low literacy levels were linked to above-average rates of personal and/or learning difficulties, low self-esteem, associated social problems, and…

  18. Etude échographique du diamètre de l'enveloppe du nerf optique chez l'enfant noir africain sain

    PubMed Central

    de Tové, Kofi-Mensa Savi; Biaou, Olivier; Adedemy, Julien Didier; Fatigba, Olatoundji Holden; Yèkpè, Patricia; Boco, Vicentia; Agossou-Voyeme, Augustin Karl

    2014-01-01

    Introduction L'objectif de cette étude était de déterminer le diamètre échographique de l'enveloppe du nerf optique (DENO) dans une population d'enfants sains noirs Africains au Bénin. Méthodes Une étude transversale descriptive a été menée sur une période de 6mois. Le DENO a été mesuré chez 304 enfants sains. Deux mesures échographiques du DENO (coupe transversale et sagittale) ont été réalisées 3mm en arrière de la papille sur chaque œil. Le DENO d'un patient est égal à la moyenne des quatre mesures. Résultats L’âge moyen était de 35, 72 ± 35,38 mois et la sex-ratio H/F de 0,96. La mesure moyenne du DENO était de 3, 31±0,54mm avec des extrêmes de 2,02 et de 4,44mm. Le DENO croît avec l’âge avec une moyenne corrélation significative (r = 0,58 et p < 0,0001). Cette croissance est plus marquée pendant les 48 premiers mois de vie. Il n'y avait pas de différence entre les garçons et les filles (p = 0, 45). Conclusion Les valeurs retrouvées dans cette étude ne diffèrent pas de ce qui est classiquement décrit dans les autres populations. Un DENO supérieur à 4,40 (IC 95%) doit être considéré comme anormal. PMID:25870740

  19. L'ilot du reservoir: etude de voisinage en milieu urbain (The Reservoir Block: A Study of a Neighborhood in an Urban Setting).

    ERIC Educational Resources Information Center

    Rey, Jean-Noel

    1983-01-01

    An analysis of a small neighborhood of Paris looks at its layout and spatial constraints, habitats, symbols, sense of territory, and rhythms and styles of the inhabitants and their roles in the group. The description, including photos, is intended for use in the French language classroom. (MSE)

  20. HIV/AIDS epidemic in French Guiana: 1979-1997. Groupe d'Etude Clinique de l'Infection VIH en Guyane Française.

    PubMed

    Sobesky, M; Dabis, F; Le Beux, P

    2000-06-01

    The incidence of AIDS in French Guiana remains one of the highest in Latin America and the Caribbean. The annual AIDS incidence rate increased continually from the start of the epidemic until 1995, when it reached 59.3/100,000 population declining thereafter to 26.6 in 1997. The prevalence of HIV in pregnant women was 0.9% in 1993, increasing to 1.3% in 1995, and that in individuals attending sexually transmitted disease (STD) clinics was 2.1% in 1996. We included 224 patients in a study of survival after AIDS diagnosis. The principal AIDS-defining diagnosis was tuberculosis in 20.5% of reported cases. The median duration of survival was 10.2 months. Multivariate analysis showed that, patients > or = 45 years at entry progressed more rapidly to AIDS than younger patients. HIV prevention and access to health care should be developed in the various ethnic communities and adapted to cultural status. The progressive implementation of multiple antiretroviral therapies since 1996 may further reduce progression of the disease but early HIV diagnosis is required to improve the overall prognosis of HIV-infected patients.

  1. Etude de la cinétique de polarisation de concentration en microfiltration du sang en régime transitoire

    NASA Astrophysics Data System (ADS)

    Ding, L. H.; Laurent, J. M.; Jaffrin, M. Y.

    1994-12-01

    In plasma separation by membrane, the blood flows tangentially along a microporous membrane while the plasma crosses the membrane under the action of a transmembrane pressure gradient. As in other cross flow filtrations of suspensions, the permeate flux increases linearly at low transmembrane pressure and reaches a plateau at high transmembrane pressure due to concentration polarization and membrane fouling. Concentration polarization consists in the formation of a high particle concentration boundary layer near the membrane which is assumed to occur rapidly, in less than one minute. In the case of plasma filtration from blood, this layer consists of cells which are rejected by the membrane and it forms a reversible secondary membrane which becomes the limiting filtration mechanism. In this condition, the permeate flux becomes approximately independent of transmembrane pressure and is controlled mostly by the shear rate. In order to study the kinetics and time scales of establishment of these phenomena, we have investigated the transient response of microporous membrane under stepped charges in transmembrane pressure. When the pressure is suddenly raised from the unpolarized regime to a level corresponding to complete concentration polarization, the permeate flux reaches a peak in 0.4-0.6s, which surpasses the equilibrium level by 60 to 80% depending upon the pressure, returning to the concentration polarization equilibrium level in 3 to 4s. These data show that the membrane retains its original permeability only during the first 0.5s of the pressure change and that concentration polarization takes about 3 to 4s to build-up. This formation time decreases with increasing pressure. When the pressure returns to its initial level, the concentration polarization disappears instantaneously and the process can be repeated at a frequency up to 0.7Hz. However, when a stepped pressure increase is applied in the concentration polarization regime, with initial pressure above 150mmHg, the permeate flux hardly changes, which confirms that once concentration polarization is established, the system membrane-polarization layer ceases to behave as a porous medium even with increased resistance. These data can explain the permeate increase observed when pressure and flow pulsations at 1Hz are superimposed on the retentate. La plasmaphérèse par membrane consiste à filtrer le plasma au travers d'une membrane microporeuse sous l'action de la pression transmembranaire. Comme toutes filtrations tangentielles, le flux de filtration augmente linéairement aux faibles pressions transmembranaires, puis atteint un plateau aux fortes pressions à cause du phénomène de polarisation de concentration et du colmatage de la membrane. La polarisation de concentration est due à la formation d'une couche fortement concentrée en soluté au voisinage de la membrane. Le temps de formation de cette couche est rapide, généralement inférieur à une minute. En microfiltration du sang, cette couche est constituée des globules qui forment une seconde membrane réversible qui limite le flux de filtration. Dans ce régime, le flux de perméat devient indépendant de la pression transmembranaire et dépend principalement du taux de cisaillement. Nous avons entrepris une étude de la réponse transitoire d'une membrane à des échelons de pression transmembranaire afin de comprendre la cinétique d'établissement de ces phénomènes. Lorsque l'on passe brusquement d'un régime non polarisé à celui polarisé, le flux de filtration croît jusqu'à un pic en 0,4 à 0,6s dépassant la valeur du plateau de 60 à 80%, puis il revient à sa valeur d'équilibre correspondant au régime de polarisation de concentration en 3 à 4s. Les données expérimentales montrent que la membrane garde une perméabilité originale pendant seulement 0,5s lors d'un changement brusque de pression et que la couche de polarisation de concentration met environ 3 à 4s à s'établir. Quand la pression transmembranaire est abaissée, la couche de polarisation disparaît également et le processus peut se répéter à une fréquence de 0,7Hz. Mais, une fois le régime de polarisation de concentration atteint, la réponse de la membrane devient négligeable. Cette étude justifie le choix d'une fréquence de 1Hz employée dans notre laboratoire en plasmaphérèse membranaire à débit pulsé.

  2. Etude de la degradation des refractaires aluminosiliceux par abrasion, chocs thermiques et corrosion par l'aluminium: Correlation et interaction des mecanismes

    NASA Astrophysics Data System (ADS)

    Ntakaburimvo, Nicodeme

    Aluminosilicate refractories used for melting and holding furnaces on which the present work was focused are submitted to mechanical abuse such as abrasion, mechanical impact and erosion, on one hand; and to chemical degradation by corrosion, as well as to thermal stresses, mostly due to thermal shocks; on the other hand. This thesis is focused on four main objectives. The first one is related to the designing of an experimental set-up allowing abrasion testing of refractories. The second deals with the separate study of the deterioration of aluminosilicate refractories by abrasion, thermal shock and corrosion. The third is the correlation between these three mechanisms while the fourth is related to the interaction between thermal shock and corrosion. One of the contributions of this thesis is the realisation of the above mentioned experimental set-up, which permits to carry out refractories abrasion testing, as well as at room and high temperature, in the absence or in the presence of molten metal. The fact of testing refractory resistance when it is submitted separately and simultaneously to the action of dynamic corrosion, erosion and abrasion leads to the studying of the influence of each of these three mechanisms on the other. One of the characteristics of the designed set-up is the fact that it allows to adjust the seventy testing conditions according to the mechanical resistance of the test material. The other important point is related to the fact the abrasion tests were carried out in such manner to permit degradation quantification, otherwise than by the traditional method of loss of weight measurement; particularly by measuring the wear depth and the residual material properties, such as the rupture force and the strength. A perfect correlation was observed between the wear depth and the loss of weight, both being negatively correlated with the residual rupture force. The abrasion resistance was found to be globally positively correlated with the original mechanical material's properties such as the modulus of rupture, the toughness and the elastic modulus. However, for same mechanical resistance for bricks and castables, the latter were more degraded because of more microstructural defects they contain. Moreover, in case of the castables, the original surface facing the mould was more abraded than a rectified surface because of the segregation phenomenon. It has been shown in this study that the abrasion process has no longer effect on material's strength unless the cracks length it promotes is higher than that of the initial defects. (Abstract shortened by UMI.)

  3. Elaboration d'un simulateur de gravure par plasma de haute densite base sur une approche cellulaire pour l'etude de profils dans divers materiaux

    NASA Astrophysics Data System (ADS)

    Saussac, Jerome

    Sub-micrometer and nanometer-size device manufacturing requires perfect control of fabrication processing, in particular plasma etching. The fabrication of such devices is complex and the requirements in terms of quality and geometry of the etching profiles impose to use the best adapted operating conditions. Simulation of space and time-etching profile evolution that is proposed in this thesis addresses these issues. The simulator yields a better understanding of the fundamental mechanisms that occur during plasma etching of features in various materials. It enables to test the influence of plasma parameters on the profile shape and thus to determine the optimal operating conditions. The development of the simulator is based on the fundamental concepts in plasma etching. From thorough review of the various numerical approaches available to simulate etching profile evolution, we have developed a stable and flexible algorithm that enables to emphasize the importance of some key-parameters for the realization of etching profiles by high-density and low-pressure plasma. The capabilities of this algorithm were tested on the study of Si sputtering in an argon plasma and of ion-assisted chemical etching of SiO2/Si in a chlorine plasma. From comparisons between simulated and experimental profiles, we have shown the importance of some parameters, like the nature of the gas, the plasma pressure, the initial shape of the mask, the mask/material selectivity, the neutral/ion flux ratio, etc. We also linked these parameters to the formation of defects in the profile, for exemple mask facetting, sidewall bowing and microtrenching. Finally, we have shown that redeposition of sputtered atoms compete with electric surface charging to explain V-shape profiles observed on Pt sputtered in argon plasmas. Keywords. plasma, etching, profile, simulation, silicon, platinum, redeposition, microtrenching

  4. Etude de l'influence de defauts sur les proprietes mecaniques de materiaux composites fabriques par le procede de placement de fibres

    NASA Astrophysics Data System (ADS)

    Legay, Pierre

    2011-07-01

    The effect of automated fiber placement defects on composite material mechanical properties needs to be characterized. Impact behavior and laminate compressive properties can be affected by these defects. This study aims at characterizing the effect of AFP defects on impact (ASTM D7136), compression after impact (ASTM D7137) and open hole compression properties (ASTM D6484) of a quasi-isotropic carbon/epoxy laminate (G40-800/5276-1). The defects that we studied were “critical” because they were located in every plies of same orientation and they were stacked. First, we performed open hole compression tests on coupons containing defects. 7 defect configurations were studied with gaps and overlaps placed in the compression direction and perpendicular to the compression direction. The results are compared with an analytical modeling of defects and they reveal that if defects are placed along compression direction they do not cause stress concentrations which lead to specimen failure. If defects are placed in plies which are perpendicular to compression direction, fiber waviness leads to a more important reduction of compressive strength. But electron microscope observations revealed that fiber waviness only affect plies that are adjacent to defects (+/-45°) and do not affect 0° plies which carry most of the load. It explains that compressive strength reduction is low even for 90° defects. Then we performed impact and compression after impact tests. We studied the results of impact tests (impactor contact force and impact absorbed energy) and we also performed ultrasonic measures (C-scan) and electron microscope observations, it allowed us to characterize impact damages. We first studied the effect of impact energy on laminate damage modes. For lower impact energies there is no damage in the material. When the impact energy increases, matrix cracking and délaminations appear, they are followed by the first fiber fractures. The damage spreads in plies which are opposed to the impact point. For higher energies, material properties are highly reduced and the laminate cannot support the load increase, the damage propagates through the laminate thickness. Finally impact and compression after impact tests performed on coupons containing defects reveal that gaps and overlaps have a local effect on damage: defects do not affect coupons global mechanical properties.

  5. Etude des lois de comportement a haute temperature en ``plasticite-fluage'', d'un acier inoxydable austenitique (12 17 SPH)

    NASA Astrophysics Data System (ADS)

    Delobelle, P.; Oytana, C.

    1986-07-01

    De façon à compléter une étude antérieure portant sur le fluage à haute température d'un acier inoxydable austénitique du Type 316 (12-17 SPH) et afin de comprendre les relations de couplage qui existent entre les grandes déformations quasiment indépendantes du temps (plasticité) et les petites déformations souvent trés lentes (viscoplasticité), toujours intimement liées pour cet alliage, nous avons réalisé différents essais à vitesse imposée: traction, traction-compression, torsion-alternée., Durant ces essais nous avons estimé l'ordre de grandeur de la contrainte visqueuse σzz = σv par la méthode de la relaxation inverse. De façon à révéler clairement les effets liés intrinsèquement au temps avons réalisé différentes séquences de vieillissement après écrouissage. Pour intégrer et décrire l'ensemble des phénonèmes observés, nous proposons un modèle unifié dont les caractéristiques principales sont les suivantes: (i) Unicité de l'équation d'état viscoplastique: ɛ = f¦σ - α¦, avec f fortement non linéaire, ce qui permet de traduire les effets dépendant et quasiment indépendant du temps. (ii) La distinction entre grande et petite déformations s'effectue à l'aide d'un critére de charge, active ou passive, portant sur la variable α. (iii) Dans l'état de microviscoplasticé, on a α = α1, tel que α 1 présente un fort coefficient d'écrouissage h0. Dans le cas inverse, on décompose α selon α = α1 = α2 + Y et tel que les coefficients d'écrouissage vérifient: H1 + Hα2 ≪ hα1 . (iv) L'effet du temps, permettant d'atteindre l'écoulement stationnaire, indifférent à l'état du système, est pris en compte par les termes de restauration dans les lois d'évolution des variables internes. On présente quelques simulations, réalisées avec le modèle développé, pour différents types de sollicitations.

  6. Etude et modelisation du frittage de pieces moulees par injection de poudres metalliques d'acier inoxydable et de superalliage de nickel

    NASA Astrophysics Data System (ADS)

    Ste-Marie, Michael

    Stainless Steel and Superalloy parts have been obtained by Maetta metal injection molding process to understand the sintering and to build a model of the shrinkage and the density by DOE after sintering. Maetta process consists of low pressure injection molding; this technology is competitive for medium series and complex geometries. The experimental procedure shows how to reduce the dimensions variability and to optimise the cost and the mechanical properties for the chosen alloys on Maetta equipments. The parts have been injected with a Maetta mixer and pneumatic presses. After that, the binder removal was done by capillary debinding. All sintering have been managed following a design of experiment (DOE) plan. The results of density measured by the Archimede's method and shrinkage were obtained by a regression model as a function of final heating ramp, soaking temperature and time. The simulation predicts experimental results with a relative error of 0,25% on the density and 2,2% for the shrinkage. The model is a good way to begin a complete simulation that regroups all effects on the dimensions of sintered parts for the Maetta process. The effects of the geometry, powder characteristics and debinding step on density and dimensions after sintering are not added in this study. Other studies would be necessary to build a global simulation.

  7. Etude du comportement sous charges laterales des ossatures de beton arme avec murs de remplissage de maconnerie, construites avant les annees 1960

    NASA Astrophysics Data System (ADS)

    Lefebvre, Karine

    Reinforced concrete structures with unreinforced masonry infills (BMR) are considered vulnerable to earthquakes. Under seismic actions, infills could fail (causing injuries or death) and cause damages to columns. In Quebec and Canada, most of BMR structures have been constructed prior to the introduction of modern seismic design codes raising question on the contribution of the infill to the structure lateral resistance. The aim of this thesis is to improve modelling technique of BMR structures built in Quebec between 1915 and 1960. This type of structures is found in hospitals or schools buildings, which must comply with some post-earthquake functionality requirements. They could also be residential or office buildings. Actually, practicing engineers usually calculate seismic capacity of BMR structures without considering the infill's structural contribution to the lateral resistance. Yet, this contribution should not be omitted. The first part of the thesis investigates the construction techniques and material properties of the old BMR structures in the Province. The results are the material properties (concrete, reinforcing steel, brick, terra cotta tile, and mortar) and the characteristics of the assemblies (wall section, reinforcement details…). The second part of the thesis presents the results of series of parametric analyses to identify among modelling and geometric parameters, which ones are the most influent on the lateral load response (rigidity, fundamental period, normal modes). Linear and modal analyses were performed. The most influent parameters identified are: number of storeys, number of bays, bay's width, soft storey, openings, upper storeys modelized (instead of being replaced by punctual loads) and the modelization technique of infills panels (strut or shell). Nonlinear static analyses have been performed to identify the most influent parameters to be considered for evaluating the lateral resistance, the capacity (load / displacement) and the yielding sequence (beam versus columns versus infills). The identified parameters are the presence of the infills, the openings and the geometric characteristics of the models (number of storeys and number of bays). One important contribution of this work is the development of an equivalent strut model to represent the action of the infill. The model could be easily implemented in standard analysis software. A central axial hinge reproducing the nonlinear behaviour of the masonry is added to the strut element. This model is a hybridization of existing proposals (FEMA and others) with added innovations by the author. It has been validated with experimental and numerical analyses results from literature. An important conclusion of this thesis is that the contribution of infills to lateral load resisting capacities of BMR structures should be considered for structure of more than one storey. Infills can add up to 51 % to bare frame capacity. The National building code requires that the lateral resistance of existing buildings must be at least 60 % of the equivalent static seismic force (V2005). It is concluded that one storey BMR buildings have a sufficient resistance, while three-storeys structures exhibit plastic deformations for loads under 0,6* V2005.

  8. Etude numerique de l'effet de l'elancement et de la garde au sol Sur le galop d'un corps rigide cylindrique a section carree

    NASA Astrophysics Data System (ADS)

    Corbeil-Letourneau, Simon

    In this thesis, the transverse galloping of square cylinders is investigated in 3D by means of a fully coupled fluid-structure interaction numerical model. More precisely, the in uence of two parameters: the aspect ratio and the presence of a gap or not are investigated. Before performing the investigation by means of 3D simulations one of the main issue to overcome is the high cost of 3D direct simulation. An important part of this cost is due to the management of the deformations of the mesh that must follow the moving body. The pseudo-solid method is a strategy to manage the deformations but it involves solving additional equations which double the number of unknowns. The use of this method have been avoided by solving the Navier-Stokes equations and the rigid body equations in the non-inertial frame of the moving body. In this frame the body is fixed, then there is no need to deform the mesh, but this comes with the side effect of an addition of fictitious force that act on the body. Because we need the force calculated in the fixed frame of the laboratory, we need to deduce the real force acting on the body. This is done by removing the fictitious force and by adjusting the mass of the body. In summary, the change of referential allows us to solve the equations at lower cost because there is no need to deform the mesh. The new. The new method has been validated on number of test cases obtained form the scientific literature. This validation have been successful and allowed us to be sure that the code solved the equations properly. Then the 3D direct simulations have been carried out to investigate the effect of aspect ratio. The analysis of the resulting data shows that the aspect ratio have weak effect on the amplitude of galloping. In other words, the effect of aspect ratio is not critical and can not explain the differences between experimental data and 2D simulations. Then, the next step have been realized, the investigation of the effect of gap below the cylinder have been carried out. This time, the analysis of data have shown that the effect on galloping is critical and play a central role in the differences already described. It has been found that there is a critical value of gap above which the inhibited galloping reappear. This means that normally, in the situation of an infinite cylinder (which situation is the 3D analog of 2D simulation), the galloping can't develop but if a sufficiently large gap is added the galloping can appear. So we conclude that the gap is the parameter that explains the difference between the galloping observed experimentally at low mass ratio and its inhibition in 2D simulations. The analysis have been pushed further. We have found that in presence of a gap, the Von Karman vortex (responsible of VIV) are formed further in the wake of the cylinder. This explains why the VIV interact less with the galloping. The flow structure involved in this phenomenon has also been identified, it's an hairpin vortex that is formed by the collision of the flow passing through the gap and an opposite flow induced by the Von Karman vortex. In summary, the question is partially answered, we know that the gap is the dominant parameter which allow the galloping to be sustained in 3D at low mass ratio. An hairpin vortex keeps away from the body the Von Karman vortex. This distance mitigates the strong interactions with the body which usually inhibit galloping in 2D at low mass ratio. But it's still not known what is the effect of the high Reynolds numbers involved in experiments. (Abstract shortened by UMI.).

  9. Contribution a l'etude et a la conception d'une machine synchrone a flux transverse destinee au degivrage d'aeronefs en cours de vol

    NASA Astrophysics Data System (ADS)

    Boussetoua, Mohammed

    During winter, the climate in the northern region is known for its icing and freezing conditions. However, emergency services often use helicopters to reach isolated locations. The difficult situations, generally experiences in the North particularly in Quebec, may prevent rescuers to intervene. The main reason preventing such operations is the lack of a de-icing system in the small helicopter blades. The overall objective of the project is research, development, design and manufacture of a system composed of an on-board rotating low speed generator and heating elements. It consumes a part of the power supplied by the turbine through the axis of the main rotor of the small aircraft and converts it to electrical power to be used by the heating elements. This innovation will allow to fly safely everywhere throughout the year protect the lives of the users even in the worst weather conditions. Firstly, the research focuses on the identification of problems related to the use of protection systems against the hoarfrost on main rotor blades of different aircrafts during flight. In this phase, we specifically focused on the difficulties encountered by the aircraft companies using the existing and operational systems for protection against hoarfrost. Main rotor blades are difficult to protect on helicopters. Several systems were considered by the helicopter manufacturers, such as electrothermal systems, pneumatic systems or using anti-icing fluids. In the current state of technological knowledge, all helicopters that have been certified to fly in icing conditions use electrothermal systems for protection against hoarfrost on their main rotor Small helicopters addressed by this work, are forbidden to fly in icing conditions due to lack of energy source to operate these systems. The electrothermal system has been considered for this thesis work to protect the main rotor blades of small aircraft in-flight. The second part of this thesis is based on the source of power feeding the hearting system. In recent years, numerous research studies have started on the development of electromechanical system converters for various applications, such as transport by road, rail or aviation. The development of new low-speed, low-weight electric machines and their very high degree of compactness has become a very promising alternative. This project strongly interests many industries in the field of air transport. The transverse flux machine is considered as a compact structure having better mass power compared to other electrical machines. The design of transverse flux machine was the subject of an electromagnetic study. Also, the analytical study helped to determine the overall dimensions of the machine. The study was followed by a validation phase of the analytical model using numerical simulations. These two studies were intended to determine changes in the characteristics of the transverse flux machine according to the different geometric dimensions of its active parts. From the calculations made using analytical and numerical models, a prototype of the transverse flux machine (600 W, 320 RPM) was designed and manufactured in the AMIL laboratory at the Universite du Quebec a Chicoutimi (UQAC). A bench test was conducted to compare the theoretical and experimental results. The measurements obtained on this prototype were compared with the theoretical results. This phase of the study demonstrates with satisfaction, the reliability of the theoretical models developed. Finally, a new configuration of this machine has been proposed. Numerical simulation results of this structure are particularly encouraging and require further investigations. For logistical and financial reasons, the prototype of this configuration has not been manufactured. (Abstract shortened by UMI.)

  10. Mechanics of Composite Materials. Summary of Some Theoretical and Experimental Studies (Mechanique des Materiaux Composites. Apercus de Quelques Etudes Theoriques et Experimentales),

    DTIC Science & Technology

    1980-06-01

    analysis). Taking into account the fragile, ductile rupture of the fibres, Le Nizerhy was led to consider the calculation, using only the hypothesis...of waves in periodic media. (Propagation M. Parodi des ondes dans les milieux pdriodiques). Dunod (1956) 3 W. Kohn Variational methods for dispersion

  11. Etude analytique du fonctionnement des moteurs à réluctance alimentés à fréquence variable

    NASA Astrophysics Data System (ADS)

    Sargos, F. M.; Gudefin, E. J.; Zaskalicky, P.

    1995-03-01

    In switched reluctance motors fed by a constant voltage source (like a battery) at high frequencies, the current becomes unpredictable and often cannot reach a given reference value, because of the variation of the inductances with the rotor position ; the “motional” m.m.f. generates commutation troubles which increase with the frequency. An optimal control as well as an approximate design of the motor require a quick and simple calculation of currents, powers and losses ; now, in principle, the non-linear electrical equation needs a numerical resolution, whose results cannot be extrapolated. By linearizing this equation by intervals, the method proposed here allows to express analytically, in any case, the phase currents, the torque and the copper losses, when the feeding voltage itself is constant by intervals. The model neglects saturation, but a simple adjustment of the inductance (chosen ad libitum) allows to deal with it. The calculation is immediate and perfectly accurate as long as the machine parameters themselves are well defined. Some results are given as examples for two usual feeding modes. Dans les machines à réluctance alimentées à haute fréquence par une source à tension constante, comme une batterie, le courant varie de manière difficilement prévisible, à cause de la variation des inductances avec la position du rotor, et souvent ne parvient pas à s'établir à une valeur de consigne imposée ; la f.é.m. “motionnelle” engendre des difficultés de communication qui s'aggravent avec l'augmentation de fréquence jusqu'à empêcher le fonctionnement. Tant pour optimiser la commande que pour dimensionner approximativement un moteur ; on doit pouvoir calculer simplement et rapidement le courant et la puissance ; or l'équation électrique, non linéaire, doit en principe être résolue numériquement et les résultats ne sont pratiquement pas extrapolables. En linéarisant par intervalles cette équation, la méthode proposée ici permer d'exprimer analytiquement et dans tous les cas les courants de phase, la puissance fournie et les pertes Joule, lorsque la tension aux bornes de l'enroulement est constante par morceaux. Le modèle utilisé néglige la saturation ; mais il est possible de tenir compte de celle-ci par des ajustements, facilement calculables, de la courbe d'inductance, quelle que soit son allure. Les calculs sont immédiats et parfaitement précis pour autant que les paramètres soient bien définis. Quelques résultats sont donnés à titre d'exemple, pour deux modes d'alimentation usuels.

  12. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des mathematiques. Proceedings of the Annual Meeting (Winnipeg, Manitoba, Canada, June 2-6, 1988).

    ERIC Educational Resources Information Center

    Pereira-Mendoza, Lionel, Ed.

    These conference proceedings include two invited lectures, four working group reports, seven reports from topic groups, one ad hoc presentation paper, a list of participants and a list of previous proceedings. The invited lectures were: "Mathematics Education and Technology" (Christine Keital); and "All One System" (Lynn A.…

  13. Canadian Journal for the Study of Adult Education = la Revue canadienne pour l'etude de l'education des adultes. 1987-1994.

    ERIC Educational Resources Information Center

    Canadian Journal for the Study of Adult Education, 1994

    1994-01-01

    These 17 issues include feature articles and perspectives on the study of adult education, as well as book reviews/recensions of works related to adult education. Some articles are written in English, and some are written in French. Among the feature articles included are the following: "The Fifties: Pivotal Decade in Canadian Adult…

  14. Home Economics/Family Studies Curricula in Canada: Current Status and Challenges = Programmes d'etudes en economie familiale et sciences familiale au Canada: Situation actuelle et enjeux.

    ERIC Educational Resources Information Center

    Peterat, Linda; Khamasi, Jennifer

    1996-01-01

    Replicating a 1984 study, a survey of home economics/family studies coordinators in the 10 Canadian provinces found the following: home economics has expanded into grades lower than 8; required courses have increased; core curriculum has not changed radically; there is increased focus on family well-being; and there is a need to address curriculum…

  15. Etude des phenomenes chimiques au contact entre le bloc cathodique et la barre collectrice d'une cellule d'electrolyse d'aluminium

    NASA Astrophysics Data System (ADS)

    Lebeuf, Martin

    La production d'aluminium est une industrie importante au Québec. Les propriétés de ce métal le vouent à de multiples usages présents et futurs dans le cadre d'une économie moderne durable. Toutefois, le procédé Hall-Héroult est très énergivore et des progrès demeurent donc nécessaires pour en diminuer les coûts financiers et environnementaux. Parmi les améliorations envisageables de la cellule d'électrolyse se trouve le contact entre la cathode et la barre collectrice, qui doit offrir une faible résistivité au passage du courant électrique. En cours d'opération de la cellule, ce contact a tendance à se dégrader, générant des pertes énergétiques significatives. Les causes de cette dégradation, pouvant provenir de phénomènes chimiques, thermiques, mécaniques et/ou électriques, demeurent mal comprises. Le but du présent projet était donc d'étudier les phénomènes chimiques se produisant au contact bloc-barre de la cellule d'électrolyse Hall-Héroult. En premier lieu, un aspect crucial à considérer est la pénétration du bain électrolytique dans la cathode, car des composés de bain atteignent éventuellement la barre collectrice et peuvent y réagir. A cet effet, une méthode novatrice a été développée afin d'étudier les cathodes et la pénétration du bain dans celles-ci à l'aide de la microtomographie à rayons X. Cette méthode rapide et efficace s'est avérée fort utile dans le projet et a un potentiel important pour l'étude future des cathodes et des phénomènes qui s'y produisent. Ensuite, une cellule d'électrolyse rectangulaire à petite échelle a été développée. Plusieurs phénomènes observés 'en industrie sur des autopsies de cellules post-opération et rapportés dans la littérature ont été reproduis avec succès à l'aide de cette cellule expérimentale. Puis, des tests sans électrolyse, ciblant l'effet du bain électrolytique sur l'acier, ont aussi été conçus et complétés afin de ségréger l'influence des différents paramètres en jeu. L'analyse des résultats de l'ensemble de ces tests a permis de constater différents phénomènes au contact bloc-barre, dont la présence systématique de NaF et, surtout, de β-Al 2O3. Outre la carburation inévitable de la barre collectrice, la formation d'une couche Fe-Al a aussi été observée, favorisée par une pénétration rapide du bain électrolytique dans la cathode ainsi que par une composition de bain acide en surface de la barre. Cette couche comportait par ailleurs des cristaux de β-Al 2O3 pouvant nuire à sa conductivité électrique. Ensuite, à des ratios de bain entre 2.5 et 4.9, une mince couche contenant les éléments Al et N peut se former en surface de la barre. Pour un bain très basique (> 6.0), c'est plutôt une couche Na 2O qui a été observée. En conditions d'électrolyse mais sans une pénétration rapide du bain dans la cathode, du Na a pu carrément pénétrer dans la barre collectrice, préférentiellement avec le carbone. De plus, de la corrosion ainsi que des couches de fer et d'oxyde de fer peuvent se former sur la barre et potentiellement dégrader la qualité du contact électrique. Pour la suite des travaux, des mesures de résistivité ainsi que l'analyse des échantillons industriels permettraient d'évaluer l'impact de ces phénomènes sur la qualité du contact. Mots-clés : Électrolyse, aluminium, Hall-Héroult, interface barre-cathode, bain électrolytique.

  16. L'acces des jeunes de regions rurales aux etudes postsecondaires (The Access of Youth from Rural Areas to Postsecondary Studies).

    ERIC Educational Resources Information Center

    Sawh, Natasha; Charron, Jocelyn

    2003-01-01

    The access to postsecondary education that is offered to students in rural areas differs significantly from the access available to urban students. An overview is given of the various factors and structural obstacles influencing rural access to postsecondary education, including aspirations, college preparation, socioeconomic characteristics of…

  17. Special Course on Unstructured Grid Methods for Advection Dominated Flows (Les Methodes Utilisant un Maillage non Structure Pour l’Etude des Ecoulements Caracterises par l’Advection)

    DTIC Science & Technology

    1992-05-01

    prisms t;- xIll with r a triangle or "tilted" such prisms , -k ( A n- ) x A ii" Ai u I)T jor tetrahedrons. Define for q _ 0 i Vl ={vL2(Sn{): vI KE(IPq...cont’d 1-47 ’Tv I 1I / _ Reference prism "Tilted prism " ,/ \\, 11 Fmo f Stn-I /7’/’/7171:1+ S~FIG. S - Space-time discrctization of the SD-method H " 2-1...impilnlentlltionI of tree strllucilres. Tihis is required so that now N, 0 I ndes coln be ticoed in the memory space released by the dolotion of -.. 0 previous

  18. Etude de l'influence du champ magnetique dans une section d'essais thermohydraulique d'un canal de reacteur nucleaire CANDU 6

    NASA Astrophysics Data System (ADS)

    Landry-Lavoie, Renaud

    This memoir deals with the effects of the magnetic fields present in a thermal hydraulic test section of the Canadian nuclear industry. This test section is used to determine the thermal hydraulic conditions that can lead to critical heat flux in a channel of a CANDU 6 nuclear reactor. To perform their series of experiments the STERN Company used strong electric currents to heat the simulation bundles with a thermal power similar to the one found in a channel of a CANDU reactor. The materials constituting the simulation channel and its supports are of ferromagnetic nature. The strong magnetic field generated by the bundles implies that they are subjected to a magnetostatic force due to the magnetization of the ferromagnetic materials. The nuclear industry wants to know if these efforts, combined with the force of gravity, are sufficient to maintain the bundles in place in the simulation channel. The question also arises whether or not the magnetic field present in the channel can affect the parameters of boiling heat transfer. To determine the magnetic field distribution in the simulation channel, we had recourse to the magnetostatic image method and the integral method of calculation of magnetization. The results of the calculations show that the magnetostatic forces exerted by the ferromagnetic elements of the test section are inferior in magnitude to the one estimated by the STERN laboratorie. We used the mechanistic model of Sullivan et al. (1964) to evaluate the possible influence of the magnetic fields on the departure diameter of the vapor bubbles. The deviation in the frequency of bubble emission was evaluated by using the correlations of Zuber et al. (1959) and Cole (1960). By introducing a magnetostatic force in the boiling model and in the correlations, we demonstrated that the magnetic field present in the STERN test section has a negligible effect on the bubble departure diameter and their emission frequency. We conclude that the conditions in the test section are consistent with those prevailing in the channel of a CANDU 6 reactor.

  19. Higher risk of death among MEN1 patients with mutations in the JunD interacting domain: a Groupe d'etude des Tumeurs Endocrines (GTE) cohort study.

    PubMed

    Thevenon, Julien; Bourredjem, Abderrahmane; Faivre, Laurence; Cardot-Bauters, Catherine; Calender, Alain; Murat, Arnaud; Giraud, Sophie; Niccoli, Patricia; Odou, Marie-Françoise; Borson-Chazot, Françoise; Barlier, Anne; Lombard-Bohas, Catherine; Clauser, Eric; Tabarin, Antoine; Parfait, Béatrice; Chabre, Olivier; Castermans, Emilie; Beckers, Albert; Ruszniewski, Philippe; Le Bras, Morgane; Delemer, Brigitte; Bouchard, Philippe; Guilhem, Isabelle; Rohmer, Vincent; Goichot, Bernard; Caron, Philippe; Baudin, Eric; Chanson, Philippe; Groussin, Lionel; Du Boullay, Hélène; Weryha, Georges; Lecomte, Pierre; Penfornis, Alfred; Bihan, Hélène; Archambeaud, Françoise; Kerlan, Véronique; Duron, Françoise; Kuhn, Jean-Marc; Vergès, Bruno; Rodier, Michel; Renard, Michel; Sadoul, Jean-Louis; Binquet, Christine; Goudet, Pierre

    2013-05-15

    Multiple endocrine neoplasia syndrome type 1 (MEN1), which is secondary to mutation of the MEN1 gene, is a rare autosomal-dominant disease that predisposes mutation carriers to endocrine tumors. Although genotype-phenotype studies have so far failed to identify any statistical correlations, some families harbor recurrent tumor patterns. The function of MENIN is unclear, but has been described through the discovery of its interacting partners. Mutations in the interacting domains of MENIN functional partners have been shown to directly alter its regulation abilities. We report on a cohort of MEN1 patients from the Groupe d'étude des Tumeurs Endocrines. Patients with a molecular diagnosis and a clinical follow-up, totaling 262 families and 806 patients, were included. Associations between mutation type, location or interacting factors of the MENIN protein and death as well as the occurrence of MEN1-related tumors were tested using a frailty Cox model to adjust for potential heterogeneity across families. Accounting for the heterogeneity across families, the overall risk of death was significantly higher when mutations affected the JunD interacting domain (adjusted HR = 1.88: 95%-CI = 1.15-3.07). Patients had a higher risk of death from cancers of the MEN1 spectrum (HR = 2.34; 95%-CI = 1.23-4.43). This genotype-phenotype correlation study confirmed the lack of direct genotype-phenotype correlations. However, patients with mutations affecting the JunD interacting domain had a higher risk of death secondary to a MEN1 tumor and should thus be considered for surgical indications, genetic counseling and follow-up.

  20. Home Economics/Family Studies Curricula in Canada: Current Status and Challenges = Programmes d'etudes en economie familiale et sciences familiale au Canada: Situation actuelle et enjeux.

    ERIC Educational Resources Information Center

    Peterat, Linda; Khamasi, Jennifer

    1996-01-01

    Replicating a 1984 study, a survey of home economics/family studies coordinators in the 10 Canadian provinces found the following: home economics has expanded into grades lower than 8; required courses have increased; core curriculum has not changed radically; there is increased focus on family well-being; and there is a need to address curriculum…

  1. CD4+ CD56+ cutaneous neoplasms: a distinct hematological entity? Groupe Français d'Etude des Lymphomes Cutanés (GFELC).

    PubMed

    Petrella, T; Dalac, S; Maynadié, M; Mugneret, F; Thomine, E; Courville, P; Joly, P; Lenormand, B; Arnould, L; Wechsler, J; Bagot, M; Rieux, C; Bosq, J; Avril, M F; Bernheim, A; Molina, T; Devidas, A; Delfau-Larue, M H; Gaulard, P; Lambert, D

    1999-02-01

    We report seven cases of particular cutaneous tumors selected from the register of the French Study Group on Cutaneous Lymphomas. The patients (three men, four women) were aged 37-86 years. They initially presented with cutaneous nodules or papules. Three cases presented with regional lymph nodes. Stagings were negative, except for one patient with bone marrow involvement. Histological features were relevant with pleomorphic medium T-cell lymphoma, but these cells exhibited a distinguishing phenotype. They were positive for CD4, CD56, and also CD45, CD43, and HLA-DR. All other T-cell and B-cell markers were negative. The myelomonocytic markers (CD13, CD14, CD15, CD33, CD117, myeloperoxidase, and lysozyme) were negative excepted CD68, which was clearly positive in four cases and weakly in two cases. Others natural killer cell markers (CD16, CD57, TiA1, granzyme B), TdT, and CD34 were negative. Polymerase chain reaction studies did not detect any B or T clonal rearrangement. The cytogenetic studies, performed in five cases, showed a del(5q) in two cases. All patients were treated successfully by polychemotherapy, but relapsed quickly in the skin, between 4 and 28 months. Five patients developed bone marrow involvement, with leukemia in three cases, and they died in 5-27 months. One patient died at 17 months with skin progression. The seventh patient is alive at 33 months, with cutaneous progression. The origin of these cells is unclear. Despite expression of CD4 or CD56, we failed to demonstrate a T-cell, natural killer cell origin. However, CD4 and CD56 are not specific for T or natural killer lineages. Although these two markers are also known to be expressed by monocytic cells, classic myeloid antigens were negative. These seven cases, together with other rare similar cases already reported, seem to represent a distinct entity likely developed from hematological precursor cells.

  2. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des mathematiques. Proceedings of the 1995 Annual Meeting (Ontario, Canada, May 26-30, 1995).

    ERIC Educational Resources Information Center

    Pothier, Yvonne M., Ed.

    These proceedings contain the papers presented at the 1995 annual meeting of the Canadian Mathematics Education Study Group. Papers are organized into four sections: (1) plenary lectures; (2) working groups; (3) topic sessions; and (4) ad hoc sessions. Papers include: (1) "The Role of Epistemology in the Analysis of Teaching/Learning…

  3. Clinical, biological, and endoscopic picture of attacks of Crohn's disease. Evolution on prednisolone. Groupe d'Etude Thérapeutique des Affections Inflammatoires Digestives.

    PubMed

    Modigliani, R; Mary, J Y; Simon, J F; Cortot, A; Soule, J C; Gendre, J P; Rene, E

    1990-04-01

    One hundred forty-two patients with active colonic or ileocolonic Crohn's disease were included in a multicenter prospective study. Data collection included 28 clinical, biological, and endoscopic items; the latter were recorded according to a standardized colonoscopic protocol; a previously validated endoscopic index of severity was calculated. Oral prednisolone (1 mg/kg body wt per day) was started and maintained until clinical remission and for at least 3 and at most 7 wk. A second clinical biological and endoscopic evaluation was then performed. At initial colonoscopy, mucosal lesions were, by decreasing order of frequency, superficial ulcerations, deep ulcerations, mucosal edema, erythema, pseudopolyps, aphthoid ulcers, ulcerated stenosis, and nonulcerated stenosis (93%, 74%, 48%, 44%, 41%, 35%, 10%, 8%, and 2% of cases, respectively). No correlation was found between the clinical activity index and any of the endoscopical data (lesion frequency and surface, endoscopic severity index). Ninety-two percent of patients underwent clinical remission within 7 wk of treatment. None of the 28 clinical biological and endoscopical items collected just before treatment could predict clinical response to steroids. Only 38 of the 131 patients in clinical remission were also in endoscopic remission. In conclusion, (a) the description and severity of colonoscopic lesions in active Crohn's disease have been quantified; (b) no correlation exists between clinical severity and nature, surface, or severity of endoscopic lesions; (c) Oral prednisolone (1 mg/kg body wt per day) induces a clinical remission in 92% of patients within 7 wk; (d) resistance to steroids cannot be predicted from the data collected before treatment onset; and (e) only 29% of patients in clinical remission also achieve endoscopic remission.

  4. Etudes sociales 30. Sujet B: Interaction entre nations. Cahier de l'eleve. Edition finale = Social Studies 30. Subject B: Interaction between Nations. Student Workbook. Final Edition.

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Curriculum Branch.

    In this Alberta (Canada) student workbook, four history units are presented for study. These are: (1) Between Two Wars (1919-1936); (2) World War II; (3) The Emergence and Interaction of the Superpowers; and (4) Contemporary World Interactions. Advice is offered to students in each unit along with information about key events and issues during…

  5. ETUDE AU MICROSCOPE ELECTRONIQUE DES TRANSFORMATIONS NUCLEAIRES DE E. COLI K12 S ET K12 S (λ26) APRES IRRADIATION AUX RAYONS ULTRAVIOLETS ET AUX RAYONS X

    PubMed Central

    Ryter, Antoinette

    1960-01-01

    Nuclear transformations induced in E. coli K12S and K12S(λ26) by ultraviolet radiations and x-rays have been studied with ultrathin sections in the electron microscope. The nucleoplasm keeps its normal aspect during "fragmentation" and during "condensation" of the nucleus into the "vesicular" form. Serial sections show that the "fragmented" nucleus consists in reality of only one very tortuous vacuole. No difference either in the shape or in the fine structure of the nucleus could be observed between the lysogenic strain and the non-lysogenic strain. A high concentration of NaCl has a "condensation" effect on the fragmented nuclei and decreases the induction rate. PMID:13745076

  6. Etudes sociales 30. Sujet B: Interaction entre nations. Cahier de l'eleve. Edition finale = Social Studies 30. Subject B: Interaction between Nations. Student Workbook. Final Edition.

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Curriculum Branch.

    In this Alberta (Canada) student workbook, four history units are presented for study. These are: (1) Between Two Wars (1919-1936); (2) World War II; (3) The Emergence and Interaction of the Superpowers; and (4) Contemporary World Interactions. Advice is offered to students in each unit along with information about key events and issues during…

  7. Etude de l'action d'un traitement par voie topique sur la synthèse de la kératine pilaire chez le Rat.

    PubMed

    Zahaf, F; Oustrin, J

    1988-06-01

    Synopsis Effect of topical treatment on pilar keratine synthesis in the rat The synthesis of keratin in pre-pubic Wistar rats has been studied under the influence of topic application of a lotion containing vegetable extracts. Changes of keratin synthesis in the rat was judged by the incorporation of a tagged precursor in the rat hair: cystein S-35 administered orally. Two protocols were followed each giving similar results. The first method concerned the regularity of hair growth with one sample taken per animal, and the second required multiple sampling in the same animal. Treatments with daily applications were in the range of 7-21 days. Results were analysed statistically in comparison with untreated zones. The excipient was tested separately in parallel. This rigorous procedure was essential, since the variations between individuals was wide in spite of the rats having been selected from the same litter. Daily application of the lotion showed an increase starting on the seventh day of the synthesis of keratin; the activity of the hair samples was already increased at this time by 90 to 400% (0.05>P>0.01). After 15 days increase reached > 1000% (P<0.05). Increase found for rats treated with the excipient do not reach significance. The hair growth cycle being 21 to 30 days, further continuation of the treatment gave only relatively weak stimulation of the keratin synthesis, the passage into the telogen phase slowing the synthesis of keratin whether it was produced from bulbar pre-keratin or synthesised in the hair itself.

  8. Non-Lethal Weapons Effectiveness Assessment Development and Verification Study (Etude d’evaluation, de developpement et de verification de l’efficacite des armes non letales)

    DTIC Science & Technology

    2009-10-01

    Sensitivity Analyses 2-9 2.4.6 Summary from Vehicle Stopper Assessment 2-11 2.5 Flash -Bang Example 2-11 2.5.1 Weapon Performance 2-11 2.5.2...Comparison of MoSEs for Alternative Required Responses 2-10 Table 2-4 PWC of Flash -Bang Hand Grenade Type A 2-11 Table 2-5 PWC of Flash -Bang Hand...Grenade Type B 2-12 Table 2-6 Target Response Thresholds for Flashes of Light 2-12 Table 2-7 MOE Assessment of Flash -Bang Hand Grenades 2-13 Table 3-1

  9. Francais: Programme d'etudes par annee scolaire. Francais langue premiere: Septieme annee (French: Yearly Curriculum. French as a Native Language: Seventh Year).

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Language Services Branch.

    The report, entirely in French, describes Alberta's curriculum for seventh-year French native language instruction, as revised in 1998. An introductory section offers background information on the curriculum's design, links between the core curriculum and French native language instruction, underlying principles of language instruction, the…

  10. Francais: Programme d'etudes du secondaire deuxieme cycle (10-12). Francais langue premiere (French: High School Curriculum [10-12]. French as a Native Language).

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Language Services Branch.

    The report, entirely in French, describes Alberta's curriculum for high school French native language instruction, as revised in 1998. An introductory section offers background information on the curriculum's design, links between the core curriculum and French native language instruction, underlying principles of language instruction, the…

  11. Francais: Programme d'etudes par annee scolaire. Francais langue premiere: Neuvieme annee (French: Yearly curriculum. French as a Native Language: Ninth year).

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Language Services Branch.

    The report, entirely in French, describes Alberta's curriculum for ninth-year French native language instruction, as revised in 1998. An introductory section offers background information on the curriculum's design, links between the core curriculum and French native language instruction, underlying principles of language instruction, the…

  12. Francais: Programme d'etudes par annee scolaire. Francais langue premiere: Huitieme annee (French: Yearly Curriculum. French as a Native Language: Eighth Year).

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton. Language Services Branch.

    The report, entirely in French, describes Alberta's curriculum for eighth-year French native language instruction, as revised in 1998. An introductory section offers background information on the curriculum's design, links between the core curriculum and French native language instruction, underlying principles of language instruction, the…

  13. Etude experimentale de quelques strategies d'apprentissage d'une langue etrangere par des adultes (Experimental Study of Some Learning Strategies in Adult Second Language Learning)

    ERIC Educational Resources Information Center

    Py, Bernard

    1976-01-01

    The intermediate competence of adult second language learners is qualitatively different from native speaker competence. Learning strategies are constants in the diachronic modifications of learner competence. A study of the acquisition of interrogatives in French reveals limited strategies and the heterogeneity of linguistic models needed to…

  14. Etude de l'apprentissage par la lecture d'etudiants en contexte d'apprentissage par problemes (APP) (A Study of Student Text-Learning Strategy).

    ERIC Educational Resources Information Center

    Cartier, Sylvie

    2002-01-01

    Examined strategies reported by students during reading to develop knowledge in their area of professional training. Discovered the reading, encoding, self-regulation, and resource management strategies used most often by students, which were not sufficient to attain effective learning. Less frequently used strategies added nuances to the…

  15. La Parabole du Gaucher et de la Casserole a Bec Verseur: Etude des Processus d'Apprentissage dans un Environnement de Calculatrices Symboliques.

    ERIC Educational Resources Information Center

    Trouche, Luc

    2000-01-01

    Discusses the problems of conceptualization of the function limit in technological environments (principally graphing calculators today and symbolic calculators tomorrow) that are gradually being adopted in precalculus teaching. Explains how the instrumentation process and the conceptualization process are dependent on each other. Sets forth a…

  16. Canadian Mathematics Education Study Group = Groupe Canadian d'Etude en Didactique des Mathmatiques. Proceedings of the Annual Meeting (Burnaby, British Columbia, Canada, May 25-29, 1990).

    ERIC Educational Resources Information Center

    Quigley, Martyn, Ed.

    These conference proceedings include two invited lectures, three working group reports, three topic group reports, two Ad Hoc group reports, a round table report, a list of participants, and a list of previous proceedings. The invited lectures were: "Values in Mathematics Education" (Ubiratan D'Ambrosio) and "Remarks on…

  17. Etude Comparative du Cout de la Vie a Rouen et a York (An Experiment in School/University Co-operation)

    ERIC Educational Resources Information Center

    Bishop, Catherine

    1975-01-01

    Sketches the preparations for and outcome of a brief trip made by twenty fourth form students, under the direction of eight university students, to a French town they had studied. The official reason was to make a comparative study of the cost of living, but cultural benefits were observed also. (MSE)

  18. Canadian Mathematics Education Study Group = Groupe Canadian d'etude en didactique des mathematiques. Proceedings of the Annual Meeting (Fredericton, New Brunswick, Canada, May 23-27, 1991).

    ERIC Educational Resources Information Center

    Quigley, Martyn, Ed.

    The proceedings report is divided into four sections that include: (1) two invited lectures by Colette Laborde and James Kaput on the topics of students' reading and writing of mathematics and an allegory in which writing is introduced into a technology-based mathematical society; (2) working group reports on the topics of fractal geometry in the…

  19. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des mathematiques. Proceedings of the 1993 Annual Meeting (York, Ontario, Canada, May 28-June 1, 1993).

    ERIC Educational Resources Information Center

    Quigley, Martyn, Ed.

    These proceedings contain papers presented at the 1993 annual meeting of the Canadian Mathematics Education Study Group. Papers are presented in four sections: (1) invited lectures; (2) working groups; (3) topic groups; and (4) ad hoc groups. Papers include: (1) "What is a Square Root? A Study of Geometrical Representation in Different…

  20. Ressources de mathematiques, maternelle-12e annee: Bibliographie annotee. Cadre commun des programmes d'etudes (Pre-Kindergarten-Grade 12 Mathematics Resources: Annotated Bibliography. Common Curriculum Framework).

    ERIC Educational Resources Information Center

    Western Canadian Protocol for Collaboration in Basic Education, Edmonton (Alberta).

    This annotated bibliography identifies French language resources endorsed for the K-12 grade levels by all Western Canadian Protocol (WCP) jurisdictions implementing the Common Curriculum Framework for K- 12 Mathematics. Resources were selected through a collaborative review process based on their high level of fidelity with the rationale,…

  1. Ressources de mathematiques, Maternelle-12e annee: Bibliographie annotee. Cadre commun des programmes d'etudes (Pre-Kindergarten-Grade 12 Mathematics Resources: Annotated Bibliography. Common Curriculum Framework).

    ERIC Educational Resources Information Center

    Western Canadian Protocol for Collaboration in Basic Education, Edmonton (Alberta).

    This annotated bibliography identifies French language resources endorsed from 1990-1999 by all Western Canadian Protocol (WCP) jurisdictions implementing the Common Curriculum Framework for K-12 Mathematics for K-12 (Common Curriculum Framework). Resources in this bibliography were selected through a collaborative review process based on their…

  2. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des mathematiques. Proceedings of the 1994 Annual Meeting (Regina, Saskatchewan, Canada, June 3-7, 1994).

    ERIC Educational Resources Information Center

    Quigley, Martyn, Ed.

    These proceedings contain papers from the 1994 annual meeting of the Canadian Mathematics Education Study Group. Papers are divided into the following sections: (1) invited lectures; (2) working groups; (3) topic groups; (4) ad hoc groups; and (5) reports on ICMI (International Committee on Mathematical Instruction) studies. Papers include: (1)…

  3. Etude par émission acoustique de la dynamique des dislocations pendant la déformation cyclique de polycristaux d'aluminium

    NASA Astrophysics Data System (ADS)

    Slimani, A.; Fleischmann, P.; Fougères, R.

    1992-06-01

    The cyclic plasticity of 5N polycrystalline aluminium have been studied at room temperature by measuring the continuous acoustic emission (A.E.) due to dislocations movements in the metal. In this study, original data have been obtained in the understanding of continuous A.E. sources. In comparison with classical interpretation given in the literature, the fact that dislocations are arranged according to a dislocation cell structure from the first cycle has been included in the analysis of the results. From this, it has been shown that the amplitude of the A.E. signal is not directly connected with the plastic strain rate prescribed to the fatigue sample and that the probability density function of dislocation loops created during the cycling can be determined. La plasticité cyclique de l'AI 5N polycristallin a été étudiée à la température ambiante à partir de mesures d'émission acoustique continue (E.A.). L'application de la technique de l'E.A. nous a permis d'obtenir des données originales quant aux mécanismes sources d'E.A. Par rapport aux interprétations classiques de la littérature, nous avons fait intervenir le fait que, dès les premiers cycles, une structure cellulaire de dislocations est établie. Nous montrons que l'amplitude du signal d'E.A. n'est plus liée directement à la vitesse de déformation plastique macroscopique. A partir de cette donnée, l'analyse des résultats d'E.A. permet d'obtenir des informations sur la fonction distribution des boucles de dislocations créées au cours de la déformation cyclique.

  4. Etude par resistivite electrique du comportement d'un alliage amorphe Fe 40Ni 38Mo 4B 18 deforme par traction

    NASA Astrophysics Data System (ADS)

    Hoang, Long Phan; Sacovy, Paulette; Delaplace, Jean

    1983-02-01

    Des rubans d'alliages amorphes Metglas du type Fe 40Ni 38Mo 4B 18 à l'état brut de trempe ont été déformés par traction à la température ambiante et l'on a suivi les variations de la résistance électrique des échantillons au cours de la déformation. Il ressort de ces essais que la déformation plastique qui est de l'ordre de 0.5% avant rupture ne se produit pas de faĉon homogène dans l'échantillon. Les mesures électriques effectuées au cours de la déformation mettent en évidence dans le domaine élastique un effet d'élastorésistance, relativement important ( K ≠ 1); elles montrent que dans le domaine plastique la déformation permanente des échantillons s'accompagne d'une diminution de la résistivité électrique du matériau. Deux hypothèses sont discutées pour expliquer cet effet inattendu, l'un qui fait appel à l'existence de volumes libres, l'autre qui suppose une cristallisation localisée du matériau sous l'effet de la contrainte.

  5. Etude des mecanismes de transport des ions chlore dans le beton en vue de la mise au point d'un essai de migration

    NASA Astrophysics Data System (ADS)

    Arsenault, Julie

    The main purpose of this research was to propose a reliable migration test to predict the chloride diffusivity of cement based materials. In this research we also studied the interaction phenomena between chloride and hydrated cement paste in order to improve our knowledge of these mechanisms. The first results of this research program showed that both chloride concentration and the composition of solutions used in the migration test may affect the chloride transport, if the equation used to calculate the diffusion coefficient does not describe correctly the transport in the migration experiment. Some tests were also conducted to characterise the microstructure of cement pastes. Results of these tests showed that neither the electrical field for a DC potential of 10 volts, nor the pure diffusion for chloride concentrations below 1,5 mol/L, do affect significantly the microstructure of cement pastes. Various w/c ratios and types of cement were also tested in this research program. Results showed that both characteristics influence the chloride transport in concrete, whether the diffusivity is calculated from the diffusion or the migration test. Results of migration and diffusion experiments showed that all ions present in the system, not only the chloride, can move under the chemical and/or electrical potential, then affecting the chloride transport into concrete. In addition, we studied interactions between chloride and cement paste by means of an immersion test. We thereby observed that some characteristics, such as the type of solution used in the immersion test, the total aluminate content of cement and the age of the material tested, do influence the chloride binding capacity of the cement paste. We also observed an acceleration of the lixiviation phenomena and significant production of ettringite. In concluding, we proposed a new method to measure the chloride binding capacity of cement paste, using samples previously tested by the migration test. Results showed that chloride binding capacity of the material measured from the migration test correspond fairly well to chloride binding capacity of material measured from the diffusion test.

  6. Etude et modélisation des propriétés dynamiques des transistors MOS de puissance radio fréquences (UHF)

    NASA Astrophysics Data System (ADS)

    Kassmi, K.; Rossel, P.; Tranduc, H.; Oms, F.

    1994-03-01

    Recent progress in the field of power MOSFET's aimed at fabricating devices whose performances in the power and frequency domains offer the opportunity of working in VHF and UHF bands. In telecommunications, the main application is the output stage (emission) in repeaters of mobile radiotelephony in the narrow bands of 890-915 MHz and 935-960 MHz, designed for the European system GSM (Global System for Mobile communications). In this paper, the main properties of the power MOSFET are analysed using an original physical model. This model is further simplified and embedded in the softwares SPICE and ELDO. Comparing the simulated and experimental static and small signal characteristics as well as the behaviour of resistive switching allows validation of our approach. Then, an UHF power MOSFET amplifier stage is analysed by considering a time domain methodology. Good agreement is found between experimental and simulated results on power gain, power output, large signal impedances and intermodulation distortion products. Les progrès effectués dans la technologie des transistors MOS de puissance permettent de réaliser des composants dont les performances en fréquence et en puissance offrent l'opportunité d'une utilisation en tant qu'amplificateur dans les bandes VHF et UHF. Dans le domaine des télécommunications, une application potentielle est l'étage de sortie—émission—des répéteurs de radiotéléphonie mobile dans les bandes étroites 890-915 MHz et 935-960 MHz allouées au système européen GSM (Groupe Spécial Mobile). Dans cet article, les propriétés et caractéristiques de ces composants sont analysées sur la base originale d'un modèle physique général, puis d'un modèle simplifié, compatible avec les logiciels SPICE et ELDO, du transistor VDMOS de puissance UHF. Des validations en régime statique, régime dynamique petit signal ainsi qu'en régime de commutation résistive sont tout d'abord présentées. Enfin, une étude plus spécifique sur les propriétés de ces transistors MOS en amplification de puissance radio fréquences — gain en puissance, puissance de sortie, impédances grands signaux, distorsion d'intermodulation d'ordre trois — est effectuée sur la base d'une méthodologie d'approche temporelle. Les comparaisons théorie — expérience sont présentées dans tous les régimes de fonctionnement ; des commentaires quant aux performances actuelles de ces produits sont faits.

  7. Etude des magnétites dopéesa`la chaux: Substitution du fer par le calcium en site tétraédrique

    NASA Astrophysics Data System (ADS)

    G´rardin, R.; Bonazebi, A.; Millon, E.; Brice, J. F.; Evrard, O.; Sanchez, J. P.

    1989-01-01

    A 1200°C, par réaction entre solides, il est possible de dissoudre partiellement le ferrite monocalcique CaFe 2O 4 dans la magnétite Fe 3O 4. Le taux maximum de substitution du cation Fe 2+ par le cation Ca 2+ est de 20% atomique. Dans la solution solide de type spinelle, les ions Ca 2+ se placent presque exclusivement en site tétraédrique. Cette distribution cationique est confirmée par l'analyse des propriétés radiocristallographiques, spectrométrie Mössbauer du 57Fe et des propriétés magnétiques.

  8. [Recent data on the epidemiology of non-Hodgkin lymphoma. Groupe d'Etudes des Lymphomes de l'Adulte (GELA)].

    PubMed

    Bosly, A; Coiffier, B

    1997-06-01

    Non-Hodgkin's lymphoma is a common condition whose incidence has increased by 75% over the last 15 years. The HIV epidemic is among the factors that have contributed to this increase: patients with AIDS have 1% annual risk of developing non-Hodgkin's lymphoma, and the increase in survival of AIDS patients has led to an increase in the frequency of AIDS-associated lymphomas. A number of other viruses are directly involved in the occurrence of lymphomas, such as the HTLV-1 and the EBV. The HSV type 8 has recently been incriminated in the occurrence of lymphomas located in the cavities of the body. The role of the hepatitis C virus in the occurrence of lymphoma is controversial. Inherited or acquired immunodeficiencies (e.g., due to treatment for an autoimmune disease or transplant) are associated with an increased incidence of lymphoma. The role of toxic chemicals, especially those used in farming, is receiving increasing attention. A number of infectious diseases promote the occurrence of lymphomas; the best illustration of this link is the association between Helicobacter pylori and primary low-grade gastric lymphomas.

  9. Prognostic significance of bcl-2 protein expression in aggressive non-Hodgkin's lymphoma. Groupe d'Etude des Lymphomes de l'Adulte (GELA).

    PubMed

    Hermine, O; Haioun, C; Lepage, E; d'Agay, M F; Briere, J; Lavignac, C; Fillet, G; Salles, G; Marolleau, J P; Diebold, J; Reyas, F; Gaulard, P

    1996-01-01

    Little is known about the expression of bcl-2 protein in intermediate and high grade non-Hodgkin's lymphoma (NHL) and its clinical and prognostic significance. We performed immunohistochemical analysis of bcl-2 expression in tumoral tissue sections of 348 patients with high or intermediate grade NHL. These patients were uniformly treated with adriamycin, cyclophosphamide, vindesine, bleomycin, and prednisone (ACVBP) in the induction phase of the LNH87 protocol. Fifty eight cases were excluded due to inadequate staining. Of the 290 remaining patients, 131 (45%) disclosed homogeneous positivity (high bcl-2 expression) in virtually all tumor cells, whereas 65 (23%) were negative and 94 (32%) exhibited intermediate staining. High bcl-2 expression was more frequent in B-cell NHL (109 of 214, 51%) than in T-cell NHL (6 of 35, 17%) (P = .0004), and was heterogeneously distributed among the different histological subtypes. Further analysis was performed on the 151 patients with diffuse large B-cell lymphoma (centroblastic and immunoblastic) to assess the clinical significance and potential prognostic value of bcl-2 expression in the most frequent and homogeneous immunohistological subgroup. High bcl-2 expression, found in 44% of these patients (67 of 151), was more frequently associated with III-IV stage disease (P = .002). Reduced disease-free survival (DFS) (P < .01) and overall survival (P < .05) were demonstrated in the patients with high bcl-2 expression. Indeed, the 3-year estimates of DFS and overall survival were 60% and 61%, respectively (high bcl-2 expression) versus 82% and 78%, respectively (negative/intermediate bcl-2 expression). A multivariate regression analysis confirmed the independent effect of bcl-2 protein expression on DFS. Thus bcl-2 protein expression, as demonstrated in routinely paraffin-embedded tissue, appears to be predictive of poor DFS, in agreement with the role of bcl-2 in chemotherapy-induced apoptosis. It might be considered as a new independent biologic prognostic parameter, which, especially in diffuse large B-cell NHL, could aid in the identification of patient risk groups.

  10. Prognostic significance of T-cell phenotype in aggressive non-Hodgkin's lymphomas. Groupe d'Etudes des Lymphomes de l'Adulte (GELA).

    PubMed

    Gisselbrecht, C; Gaulard, P; Lepage, E; Coiffier, B; Brière, J; Haioun, C; Cazals-Hatem, D; Bosly, A; Xerri, L; Tilly, H; Berger, F; Bouhabdallah, R; Diebold, J

    1998-07-01

    Peripheral T-cell lymphomas (PTCL) have been generally reported to have a worse prognosis than B-cell lymphomas (BCL). Because of their heterogeneity and scarcity, the outcomes of the different histological subtypes have not been compared. From October 1987 to March 1993, 1,883 patients with diffuse aggressive non-Hodgkin's lymphomas (NHL) included in the LNH87 protocol could be assessed for both morphology and immunophenotyping. Among them, 288 (15%) had PTCL and 1,595 (85%) had BCL. According to the Kiel classification, most PTCL were classified as angioimmunoblastic (AIL; 23%), pleomorphic medium and large T-cell (PML; 49%), or anaplastic large cell (ALCL; 20%) lymphomas. Comparing PTCL with BCL patients, the former had more disseminated disease (78% v 58%), B symptoms (57% v 40%), bone marrow involvement (31% v 17%), skin involvement (21% v 4%), and increased beta2-microglobulin (50% v 34%), whereas BCL patients had more bulky disease (41% v 26%). According to the International Prognostic Index (IPI), PTCL and BCL scores were, respectively: 0 factors, 13% and 15%; 1 factor, 17% and 22%; 2 factors, 24% and 25%; >/=3 factors, 45% and 37% (P = .09). For BCL and PTCL, respectively, complete remission rates were 63% and 54% (P = .004); the 5-year overall survival (OS) rates were 53% and 41% (P = .0004) and event-free survival (EFS) rates were 42% and 33% (P < . 0001). Comparison of the different histological subtypes of lymphoma showed that the 5-year OS rate for T-ALCL (64%) was superior to those of other PTCL (35%) as well as diffuse large B-cell (53%) NHL. When multivariate analysis was applied using the IPI score as one factor, nonanaplastic PTCL remained an independent parameter (P = . 0004). Although the poor prognosis of non-ALCL PTCL could be due in part to the presence of adverse prognostic factors at diagnosis, this study shows that the T-cell phenotype is an independent significant factor, which should be incorporated into the definition of prognostic groups.

  11. Prognostic significance of Epstein-Barr virus in nodal peripheral T-cell lymphoma, unspecified: A Groupe d'Etude des Lymphomes de l'Adulte (GELA) study.

    PubMed

    Dupuis, Jehan; Emile, Jean-François; Mounier, Nicolas; Gisselbrecht, Christian; Martin-Garcia, Nadine; Petrella, Tony; Bouabdallah, Reda; Berger, Françoise; Delmer, Alain; Coiffier, Bertrand; Reyes, Félix; Gaulard, Philippe

    2006-12-15

    Peripheral T-cell lymphomas (PTCLs) are rare and have a dismal prognosis. The most frequent subtype is PTCL, unspecified. Epstein-Barr virus (EBV) has been detected in around 40% of cases, but its prognostic significance is not fully established. Lymph node samples from 110 patients with PTCL, unspecified included in LNH87 and LNH93 trials were available. EBV status was studied by EBV-encoded small RNA in situ hybridization (EBER-ISH). EBER-ISH showed positive cells in 45 (41%) of 110 patients. Pretreatment characteristics were comparable between positive and negative cases, except for male sex (80% versus 60%, respectively, P = .02). Only 50% of patients achieved complete remission with a 5-year event-free survival (EFS) and overall survival (OS) of 21% and 30%, respectively. EBER-ISH positivity was the sole factor linked with worse EFS, with a 5-year probability of 11% for positive patients. In univariate analysis, factors affecting OS were EBER-ISH positivity, high LDH level, and age older than 60 years. In multivariate analysis, EBER-ISH was associated with a worse OS in the elderly population. Time-dependent analysis showed that the negative impact of EBV was essentially seen in the first 2 years following diagnosis. These results warrant further studies regarding pathogenesis and specific treatment approaches for EBV-associated PTCL patients.

  12. Etude des parametres physiques en vue d'applications medicales de l'actionnement magnetique de dispositifs medicaux par un systeme d'imagerie par resonance magnetique

    NASA Astrophysics Data System (ADS)

    Mathieu, Jean-Baptiste

    An actuation and control method for medical devices based on the magnetic gradient coils of a Magnetic Resonance Imaging (MRI) was proposed for the first time in 2002 by NanoRobotics Laboratory [1]. The work undertaken in the present thesis began in the context of demonstrating the concept of automatic navigation of a magnetic bead in vivo. From the point of view of actuation, models and experimental data correlate. A maximum velocity of 13cm/s was measured for a 1.5mm diameter chrome steel bead in the carotid artery of a living swine. The bead was under the influence of magnetic gradients applied by a clinical MRI system without any hardware modification. In light of these results, the aim of this thesis is the study of the physical parameters involved in the development of a first medical application: the steering of magnetic particles in MRI in the context of drug targeting. It was demonstrated that an MRI system equipped with a set of magnetic gradient coils with enhanced amplitude was able to apply a high enough actuation force to act upon magnetic microparticles suspended in a liquid. General rules for MRI actuation were identified. First of all, increasing the amplitude of the main magnetic field of the MRI leads to the increase of the actuation force amplitude only until the ferromagnetic body reaches its saturation magnetization. Moreover, soft ferromagnetic bodies appear to be better candidates for MRI based magnetic actuation because they can reach high saturation magnetizations. Magnetic gradient amplitude appears as a foremost factor to increase the amplitude of the magnetic force. Clinical MRI systems do not provide gradients with high enough amplitude for the applications studied here. Theoretical models developed in this thesis predict that a one order of magnitude increase in gradient amplitude would be required. Implementing actuation dedicated gradient coils is therefore suggested. Finally, a larger ferromagnetic body will lead to higher magnetophoretic velocities for magnetic particles. In the context of magnetic microparticle targeting for cancer treatment through embolisation, the scaling laws bridging from the preliminary works with millimeter sized beads to magnetic microparticles suspensions were studied. Magnetic microparticles suspensions injected through branching channels were guided in MRI under the influence of magnetic gradients. The goal of these experiments was to maximize the amount of particles flowing through one of the outlets of the channel. The outcome of the experiments was quantified using an optical set-up as well as by analyzing the suspension at each outlet of the channels. The most important parameters that were identified are the magnetic force amplitude, the interactions and aggregation between magnetic particles of the suspension, the size, geometry and density of the particles or aggregates driven, the dimensions of the channel and the intensity of the flow. Mathematical models based on analyses of particle trajectories and on non dimensionalization of the experimental parameters were proposed. The model predicts steering efficiencies in the order of what was recorded experimentally. Nevertheless, some parameters that remain to be quantified more precisely like the effects of magnetic aggregation and friction forces cause discrepancies between theoretical and experimental data. Despite these differences, the knowledge gained in the field of magnetic suspension steering appears to be sufficient to envision in vivo experiments lead in parallel with improving the theoretical predictions. Hence, an experimental set-up and an experimental protocol are being designed to adapt the steering methods to interventional procedures and animal subjects. Finally, the same principles used for microparticle steering can be applied for magnetic catheter navigation. Hence, on the side of the main subject of this thesis, the deflection of magnetic catheters by MRI was also studied as a second medical application. Using magnetic catheter and guide wires could facilitate the placement of medical instruments and accelerate medical procedures. The recorded deflections are lower than the ones measured with other magnetic guidance systems. The parameters and performances obtained are functions of the amplitude of the applied magnetic force and material strength properties of the catheters or guide wires. Hence, deflection could be enhanced by adapting the mechanical properties of the devices, by increasing the amplitude of the magnetic gradient or the volume and magnetization of the magnetic tip. These latter results are the object of an upcoming patent application. Hence, the paper relating them could not be submitted prior to the submission date of this thesis. For this reason, this paper's manuscript is presented as an annex of the present document

  13. Poesies et chansons francaises: base pour l'etude de la langue et de la civilisation (French Poetry and Songs: Basis for the Study of Language and Civilization)

    ERIC Educational Resources Information Center

    Elliott, Jacqueline C.

    1977-01-01

    Notes the linguistic and cultural advantages of using songs, poems and rhymes as aids in learning French. Some teaching methods, instructional uses and learning exercises are suggested. (Text is in French.) (CHK)

  14. Etude des Coefficients du Viriel de la Constante Dielectrique des Gaz Atomiques et de L'azote EN Fonction de la Temperature

    NASA Astrophysics Data System (ADS)

    Huot, Jacques

    1990-01-01

    Le but principal de notre travail fut d'etudier le deuxieme coefficient du viriel de la constante dielectrique (B_epsilon) des gaz atomiques en fonction de la temperature. Nous avons developpe une technique differentielle afin de determiner B_ epsilon avec precision. Les mesures furent effectuees a 77.4 K, 242.95 K, 323.15 K et 407.6 K et a des pressions allant jusqu'a 600 bars. Pour tous les gaz atomiques, nous avons mesure un accroissement de la valeur de B_epsilon lorsque la temperature diminue. Nos resultats precis de B_epsilon en fonction de la temperature vont permettre d'ameliorer les calculs ab-initio existants. Le B_ epsilon des gaz atomiques semble presenter un comportement universel similaire a celui du deuxieme coefficient du viriel de la pression (B_ {rm P}). Pour l'azote, la valeur du moment quadrupolaire que nous avons mesuree est en accord avec la valeur theorique ainsi qu'avec les valeurs determinees par d'autres methodes experimentales.

  15. Etude des transitions de phase dans le modele de Higgs abelien en (2+1) dimensions et l'effet du terme de Chern-Simons

    NASA Astrophysics Data System (ADS)

    Nebia-Rahal, Faiza

    2009-12-01

    We investigate, via Monte Carlo simulations, non-perturbative properties of a 2+1 dimensional Abelian Higgs model without and with the Chern-Simons term in the symmetry broken phase in terms of its topological excitations: vortices and anti-vortices. The aim of the present work is to understand what phases exist for the system in that sector and the effect of the Chern-Simons term on the confining potential induced between external charges found by Samuel. We formulate a lattice description of the effective model starting from a tetrahedral tessellation of Euclidean three space to generate non-intersecting closed vortex loops. In the presence of the Chern-Simons term, for a given configuration, we formulate and compute the linking number between different closed vortex loops. We analyse properties of the vacuum and compute the expectation value of Wilson loop operator, Polyakov loop operator at different temperatures and the 't Hooft loop operator in the presence of the Chern-Simons term. In the absence of a Chern-Simons term, as we vary the mass of the vortex loops, we find two distinct phases in the symmetry broken sector, the usual Higgs phase and a novel phase which is heralded by the appearance of the so-called infinite loops. On the other hand, we find that the force between all external charges is screened, corresponding to a perimeter law for the Wilson loop implying no confinement. However, after the transition, we find that small external charges are still screened, but after a critical value of the external charge, free energy diverges. In the presence of Chern-Simons term, and in the limit where the coupling constant is low for Chern-Simons we find that the behavior of Wilson loop does not change: it is still a perimeter law, implying no confinement. Moreover, the Chern-Simons term does not contribute to the Wilson loop. 'tHooft loop behaves like a perimeter law too. Key words: abelian Higgs, confinement, Chern-Simons, vortex- antivortex pair, vortex loop, Linking number, Monte Carlo simulations, phase transition.

  16. Etude calorimétrique et structure cristalline du putrescinium monohydrogénomonophosphate dihydrate NH 3(CH 2) 4NH 3HPO 42H 2O

    NASA Astrophysics Data System (ADS)

    Kamoun, Slaheddine; Jouini, Amor

    1990-11-01

    Chemical preparation, calorimetric studies, and crystal structure are given for a new monophosphate. The putrescinium monohydrogen monophosphate dihydrate salt is monoclinic with the unit cell dimensions a = 6.541(1) Å, b = 16.648(3) Å, c = 9.175(1) Å, β = 95.74(1)°, V = 994.1(5) Å 3, Dm = 1.498 Mgm -3, Dx = 1.484 Mgm -3, μ = 2.732 mm -1, space group {P2 1}/{c} with Z = 4. The structure was solved by the Patterson method and refined to a final value of 0.046 for 1732 observed independent reflections. The structure shows a layer arrangement perpendicular to the overlinec axis: planes of the [HPO 4] 2- tetrahedra alternate with planes of the [(CH 2) 4(NH 3) 2] 2+ dication. The zeolitic water molecules are located between these planes separated by a distance of 2.294 Å. The monohydrogen phosphate group is roughly tetrahedral with the symmetry 3 m. The PO distances in this group range from 1.495(2) to 1.592(2) Å. The amino groups of putrescine are protonated. The putrescinium dication has an extensive all- trans configuration with a noncrystallographic inversion center. The cohesion and the stability of the atomic arrangement result from three kinds of hydrogen bonds, NH····O, POH····O(w), and O(W)H····O. The differential scanning calorimetric study shows that the dehydration of this salt occurs in two steps respectively at 105 and 121°C with a loss of one water molecule per step. The anhydrous salt undergoes four phase transitions respectively at temperatures of 133, 143, 159, and 165°C.

  17. Etude de la transmission sonore par voie externe d'un bouchon d'oreille couple au conduit auditif: Modelisation numerique et validation experimentale

    NASA Astrophysics Data System (ADS)

    Viallet, Guilhem

    The objective of this thesis is to contribute to the better understanding of the problem of the sound transmission through the earplug-earcanal system to improve the design of the protector, to contribute to a better assessment of its effectiveness and thus ultimately to improve the worker's protection. This objective is accomplished via a methodological development of a predicting tool to simulate the attenuation in the framework of a step by step modeling approach which integrates gradually geometrical and physical complexities. In the first step, only the geometrical aspect of the ear canal is studied via the question of the validity of a simplified 2D axisymmetric description of the ear canal geometry in the case of rigid boundary conditions. This choice of boundary conditions allows in a first approximation to set aside the problems associated with the integration of the earcanal constitutive tissues. This question is investigated through comparisons of attenuation predictions with 2D and 3D models, and for individual or averaged over a group cases. The emphasis is put on finding the most reliable 2D geometry reconstruction method (in terms of attenuation prediction) which can be used, in order to define a 2D axisymmetric geometry based on geometrical characteristics of a 3D one. In the second step, the previous 2D model is extended to take into account a layer of skin on the ear canal walls. This also corresponds to a configuration of the synthetic earcanal included in the acoustical test fixtures that are commonly used to measure the attenuation. The role of the skin and its effect on the earplug attenuation are studied. The contributions of the different acoustic pathways due to an airborne excitation are quantified. More generally, the investigation concerns the energy circulating within the domain. In addition, statistical analyses were performed to quantify the effect on the attenuation of the mechanical parameters of both the skin and the earplug. In the third step, the previous model is extended to take into account the others tissues surrounding the ear canal (bone and soft tissues). Moreover, the previous geometry (the cylindrical one) is partially modified to obtain an average 2D axisymmetric ear canal geometry with a variable cross section. This model is first validated by comparisons with measurements on human subjects and then exploited to quantify the impact of various factors known to vary the attenuation when measured in laboratory conditions. These factors are: the possible presence of leaks, the insertion depth of the earplug, the inter-individual variation of the ear canal geometry and the variation of the mechanical parameters associated with the surrounding tissues. These factors are introduced one by one in the model and their impact on the attenuation is quantified and thereafter compared to standard deviations obtained from attenuation measurements on human subjects. Such comparisons are used to evaluate the predominance (as a function of the frequency) of the aforementioned factor effects on the attenuation. In the fourth step, the study goes into the possibility of replacing the surrounding tissues of the ear canal by mechanical impedance boundary conditions. This work ultimately aims to simplify the models developed in the third step, by using models of steps 1 and 2 improved by the mechanical impedance boundary conditions rather than the more conventional condition limits (the fixed one) used till now. Two tissue replacement scenarios have been tested in the 2D axisymmetric configuration described in the first approximation. In the first scenario (similar to step 1), the effect of all the tissues (skin, soft tissue and bone) were reduced to a mechanical impedance. A second scenario, a little less simplified, where only the bone and soft tissue domains are replaced is then considered. This second scenario allowed to correct the limitations obtained in the first scenario and helped to achieve more realism in terms of attenuation predictions, closer than those obtained with the model developed in step 3. These tests were performed on a unique geometry that does not allow generalizing the method validation which could be extended in future works to 3D models or 2D axisymmetric models with variable cross sections. From a scientific point of view, each of the steps described above helped to better understand the key mechanisms involved in the attenuation of an earplug, the pathways leading the acoustic transmission in the case of an airborne sound excitation through the occluded ear canal, and to investigate the possible simplification which can be done to predict a realistic attenuation with a numerical model. From a technological point of view, the sensitivity analyses performed on the earplug mechanical parameters with the modeling tools developed in this thesis provide concrete ways for the manufacturers to improve their product effectiveness. (Abstract shortened by UMI.).

  18. Etude des transitions de phases de NH 3(CH 2) 2NH 3(H 2PO 4) 2 par mesures optique, dielectrique et de thermocourant

    NASA Astrophysics Data System (ADS)

    Kamoun, S.; Daoud, A.; Von Der Muhll, R.; Ravez, J.

    1993-02-01

    Dielectric, birefringence and thermocurrent measurements have been carried out on NH 3(CH 2) 2NH 3(H 2PO 4) 2 single crystal. Three transitions have been detected at about T 1 = (264 + 4), T 2 = (241 + 5) and T 3 = (141 + 5) K. In the low temperature phases a polarization current of about 10 -8 - 10 -9 A is obtained and can be reversed when the sign of the polarization field is changed, a property which could correspond to a ferroelectric behaviour. However, no pyroelectric current is detected when the temperature decreases from T t. Another hypothesis, based on a field - induced polarization, has been considered : the depolarization current could be due to charge displacements from potential minima favored by rising temperature. In any way, the low - temperature phases are characterized by a remanent polarization.

  19. Higher Education and Social Origin in France: A Statistical Study of Inequalities Since 1965 = Enseignement Superieur Et Origine Sociale En France: Etude Statistique Des Inegalites Depuis 1965

    ERIC Educational Resources Information Center

    Jaoul, Magali

    2004-01-01

    Mass education has the goal of guaranteeing the same education to all in order to moderate differences between individuals and promote a kind of "equality of opportunity." Nonetheless, it seems clear that lower-class youths do not benefit as much from their degree or university experience as do those who come from more privileged…

  20. Bibliographie annotee de ressources complementaires. Etudes sociales: Secondaire, 7e a 12e (Annotated Bibliography of Further Resources. Social Studies: Secondary School, Grades 7-12).

    ERIC Educational Resources Information Center

    Soucy, Claire, Comp.; Hebert, Lorraine, Comp.

    This annotated bibliography offers resources for teaching the social studies for grades 7 through 12. Subject areas include: (1) grade 7 - culture of Canada and Japan, as well as multicultural and bilingual Canada; (2) grade 8 - the geography of Canada, the United States, and the case of Brazil in South America; (3) grade 9 - economic perspectives…

  1. Etude comparative sur la propagation de l'endommagement apres impact des composites carbone/epoxy renforces par piquage au fil Kevlar et titane-nickel

    NASA Astrophysics Data System (ADS)

    Vachon, Pierre-Luc

    Composite laminates have strong in-plane mechanical properties, but they are generally weaker through their thickness. This specificity makes the laminates prone to delamination, particularly under low-velocity impact loads. Consequently numerous research efforts have been dedicated to developing interlaminar reinforcing methods, such as transverse stitching. The present project proposes the use of the stitching technique combined with a special stitching thread made of superelastic TiNi alloy. This technology is intended to improve the delamination toughness in composite laminates loaded in bending. In the first part of this study a numerical model was developed for analyzing composite structures. The 3-D finite element model was built with the ANSYS commercial software using 20-node solid and 8-node shell elements. The progressive damage modeling technique was used, allowing the prediction of delamination propagation in a laminate submitted to various loading modes. The model was validated for a plate under quasi-static traction load, and it was then used to simulate three-point bending tests. Secondly, carbon/epoxy composite panels were fabricated, with each panel containing unstitched and stitched specimens. Two different materials were used for the stitching thread: superelastic TiNi wires and Kevlar threads as a reference. Some stitched specimens were cut in slices in order to make some observations of the internal stitch using an optical microscope. Standardized low-velocity impact tests and compression after impact tests were carried out on stitched and unstitched specimens (ASTM D7136 and D7137). The Kevlar reinforcements have shown great performance in reducing the delaminated zone after impact, as well as in improving the residual compression strength. The TiNi reinforcements provided encouraging results during the impact tests, though being less effective than the Kevlar threads. During the compression after impact tests, only a slight difference could be measured between the TiNi-stitched and the unstitched specimens. Then the bending performance of the specimens was quantified experimentally by calculating the energy required to create a unit volume of damaged material (Gv, J/mm3). This metric is similar to the Strain Energy Release Rate (SERR) commonly used in studies on delamination. According to the experimental results, the damage resistance in three-point bending was not improved by the Kevlar reinforcements, despite the reduced damaged zone after the impact test. Indeed, when the strain energy in bending is relativized to the induced damaged volume during propagation, it turns out that the TiNi reinforcements are more effective than the Kevlar's for improving the damage resistance. Finally, the numerical study on the behavior of both types of stitched reinforcements allowed identifying subtle differences between those. Indeed, both stitching threads (TiNi and Kevlar) promoted the interlaminar propagation of the delamination during simulation of the bending test, with this behavior being less pronounced for the TiNi-stitched plate. However the Kevlar threads seemed more effective for stopping this propagation in the zones between the stitches. Keywords: composite materials, stitching, numerical model, shape memory alloy, three-point bending, low-velocity impact, ultrasound imaging.

  2. Le francais parle dans la ville de Quebec: une etude sociolinguistique (The Spoken French in the City of Quebec: A Sociolinguistic Study). Publication G-1.

    ERIC Educational Resources Information Center

    Deshaies, Denise

    This study is divided into two major sections. The first, the study of language in a sociolinguistic perspective, includes: (1) an analysis of the attitudes associated with linguistic variation, and a review of (2) studies conducted in French Quebec, (3) the linguistic and cultural deficit theories, (4) the theory of cross-linguistic and…

  3. Etude des aspects cliniques, échographiques et nutritionnels du syndrome des ovaires micropolykystiques (SOMPK) à Mbuji-Mayi, RD du Congo

    PubMed Central

    Kalenda, Louis Mbuyamba Ntobo; Mikenji, Justin Biayi; Nkoy, Albert Mwembo-Tambwe; Kayamba, Prosper Kalenga Muenze

    2014-01-01

    Introduction Le Syndrome des Ovaires Micropolykystiques (SOMPK) est polymorphe. L'objectif de cette étude était de déterminer la prévalence et rechercher les facteurs nutritionnels éventuellement associés. Méthodes Chez 300 patientes atteintes de SOMPK faisant l'objet de cette étude, les données anamnestiques, cliniques et échographiques, et les habitudes alimentaires ont été analysées. Les statistiques usuelles et les mesures d'association ont été utilisées pour analyser les résultats. Résultats La prévalence de SOMPK était de 23,6%. L’âge moyen des patientes avec SOMPK était 24 ± 7 ans et chez celles sans SOMPK 36 ± 7 ans (P < 0,05). Le risque de développer le SOMPK en présence d'un niveau de vie élevé était de 2,03 (RR = 2,03; IC à 95%: 1,73-2,38; P = 0,00). Le risque de développer le SOMPK en exerçant une activité légère est de 2,15 (RR = 2,15; IC à 95%: 1,87-2,87; P= 0,00). La proportion des patientes avec SOMPK ayant accumulé plus de 2400 kcal était de 59% vs 36% (P < 0,05) et le risque de développer le SOMPK lorsque l’énergie accumulée était supérieure à 2400 kcal était de 1,57 (RR = 1,57; IC à 95%: 1,33-1,85; P= 0,00). Conclusion Dans notre milieu la prévalence de SOMPK était de 23,6%. Les facteurs associés au SOMPK étaient l’âge, l’énergie accumulée de plus de 2400 Kcal, le niveau socio-économique élevé et l'activité physique légère. Des études analytiques plus poussées sont nécessaires, pour évaluer la force du risque que représentent ces différents facteurs étudiés. PMID:25870722

  4. Processus de modelisation et etude des orages geomagnetiques dans les reseaux electriques: Impact sur le reseau de transport d'Hydro-Quebec

    NASA Astrophysics Data System (ADS)

    Abdellaoui, Amr

    This research project presents a complete modelling process of the effects of GIC on Hydro-Quebec power system network for system planning studies. The advantage of the presented method is that it enables planning engineers to simulate the effects of geomagnetic disturbances on the Hydro-Quebec System under different conditions and contingencies within reasonable calculation time frame. This modelling method of GIC in electric power systems has been applied to the Hydro-Quebec System. An equivalent HQ DC model has been achieved. A numerical calculation method of DC sources from a non-uniform geoelectric field has been developed and implemented on HQ DC model. Harmonics and increased reactive power losses of saturated transformers have been defined as a function of GIC through a binary search algorithm using a chosen HQ magnetization curve. The evolution in time of each transformer saturation according to its effective GIC has been evaluated using analytical formulas. The reactive power losses of saturated transformers have been modeled in PSS/E[1] HQ network as constant reactive current loads assigned to the corresponding transformer buses. Finally, time domain simulations have been performed with PSS/E taking into account transformer saturation times. This has been achieved by integrating HQ DC model results and analytical calculations results of transformer saturation times into an EMTP load model. An interface has been used to link EMTP load model to HQ PSS/E network. Different aspects of GIC effects on the Hydro-Quebec system have been studied, including the influence of uniform and non-uniform geoelectric fields, the comparison of reactive power losses of the 735kV HQ system with those of Montreal network, the risks to voltage levels and the importance of reactive power dynamic reserve. This dissertation presents a new GIC modelling approach for power systems for planning and operations purposes. This methodology could be further enhanced, particularly, the aspect regarding the transformer saturation times. Hence more research remains to be pursued in this area.

  5. Long-term outcome of adults with systemic anaplastic large-cell lymphoma treated within the Groupe d'Etude des Lymphomes de l'Adulte trials.

    PubMed

    Sibon, David; Fournier, Marion; Brière, Josette; Lamant, Laurence; Haioun, Corinne; Coiffier, Bertrand; Bologna, Serge; Morel, Pierre; Gabarre, Jean; Hermine, Olivier; Sonet, Anne; Gisselbrecht, Christian; Delsol, Georges; Gaulard, Philippe; Tilly, Hervé

    2012-11-10

    Systemic anaplastic large-cell lymphoma (ALCL) is a T-cell lymphoma, whose anaplastic lymphoma kinase (ALK) expression varies according to age. Long-term outcomes of chemotherapy-treated adults are not definitively established and should be evaluated. Patients treated in three Groupe d'Étude des Lymphomes de l'Adulte prospective clinical trials with confirmed systemic ALCL after immunohistopathologic review and defined ALK expression status were analyzed. Among the 138 adult patients with ALCL, 64 (46%) were ALK positive, and 74 (54%) were ALK negative. Median follow-up was 8 years. At diagnosis, significantly more patients younger than 40 years old were ALK positive than ALK negative (66% v 23%, respectively; P < .001). Comparing patients with ALK-positive and ALK-negative ALCL, β(2)-microglobulin was ≥ 3 mg/L in 12% and 33% (P = .017); International Prognostic Index was high (score, 3 to 5) in 23% and 48% (P = .03); complete response rates to first-line treatment were 86% and 68% (P = .01); and 8-year overall survival (OS) rates were 82% (95% CI, 69% to 89%) and 49% (95% CI, 37% to 61%), respectively (P < .001). The survival difference mostly affected patients age ≥ 40 years. Multivariate analysis identified β(2)-microglobulin ≥ 3 mg/L (P < .001) and age ≥ 40 years (P = .029), but not ALK status, as prognostic for OS. These two variables distinguished four survival risk groups, with 8-year OS ranging from 84% to 22%. CONCLUSION Results of this long-term study enabled refinement of the prognosis of adult systemic ALCL, with ALK prognostic value dependent on age, and could provide guidance for eventual treatment adjustment.

  6. Etude de la preparation de poudres et de depots a partir de suspension par plasma inductif: Le cas de l'hydroxyapatite phosphocalcique

    NASA Astrophysics Data System (ADS)

    Bouyer, Etienne

    The work presented in this thesis has been directed to the study and the development of a new thermal spray process now known as the "SPS" (Suspension Plasma Spraying), in which the raw material to be treated is initially a liquid suspension. The SPS process is employed either for the preparation of thick coating or to the production of spherical and dense powders. The principle of SPS is the axial injection of a suspension into the plasma core by gas atomization. The atomization droplets are successively dried, melted and accelerated in the plasma plume. Finally, melt droplets strike a substrate and solidify to build the coating (deposition route) or are solidified in-flight and are then collected from within the reactor (powder route). The SPS process is best achieved with the use of r.f. thermal plasma technology and has been applied to the complex shape forming of ceramic materials: e.g. hydroxyapatite (HA), Ca10(PO4)6(OH) 2. HA, which is a bioceramic used in various biomedical applications such as bone substitute. The original chemical synthesis of the HA is a key step for the control of physical and chemical properties of the HA suspension which in turn are fundamental to the success of the entire SPS process. HA decomposes at elevated temperatures. With proper control of the plasma spraying parameters (i.e. the nature of the plasma gas and its composition, plasma power level, pressure, etc), the in-flight plasma decomposition can be minimized. Moreover it is possible to control the coating texture, its crystallinity and adhesion strength while maintaining high deposition rates (>150 mum/min). The morphology of powders prepared by the SPS technique and the size of resultant powders depends strongly on the atomization parameters of the spray suspension in the plasma. Water promotes the stabilization of HA during the plasma treatment and therefore helps to limit its in-flight decomposition. The SPS process is a potentially powerful technology providing in-flight reaction routes for new materials synthesis and shaping, both as powders and as finished coatings. A further advantage of the SPS process concerns its economics through the used of a reduced number of process steps required in comparison to conventional plasma spray process.

  7. Cubitus varus: l'ostéotomie de soustraction externe a-t-elle toujours sa place? Etude rétrospective à propos de 25 cas

    PubMed Central

    Chagou, Aniss; Bassir, Réda Allah; Rhanim, Abdelkarim; Lahlou, Abdou; Berrada, Mohammed Saleh; Yaacoubi, Moradh

    2016-01-01

    Le cubitus varus est cal vicieuxle plus souvent secondaire à des fractures supracondyliennes déplacées de l'extrémité inférieure de l'humérus chez l'enfant. Différentes techniques chirurgicales ont été proposées avec un taux de réussite différents mais aussi un taux de complications rapportées différents. Nous évaluons à travers une étude rétrospective de 25 cas colligés au centre hospitalier universitaire de Rabat, les résultats de la technique de soustraction externe que nous utilisons dans notre formation pour prendre en charge cette déformation. PMID:27516828

  8. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des matematiques. Proceedings of the Annual Meeting (St. Catharines, Ontario, Canada, May 27-31, 1989).

    ERIC Educational Resources Information Center

    Pereira-Mendoza, Lionel, Ed.; Quigley, Martyn, Ed.

    These conference proceedings include two invited lectures, four working group reports, five topic group reports, a list of participants, and a list of previous proceedings. The invited lectures were: "Teaching Mathematical Proof: Relevance and Complexity of a Social Approach" (Nicolas Balacheff) and "Geometry Is Alive and…

  9. Etude infrarouge des effets de structure et de solvant sur la frequence itvC=O de cetones aliphatiques saturees. Relation frequence- topologie-milieu

    NASA Astrophysics Data System (ADS)

    Massat, A.; Dubois, J. E.

    1980-08-01

    The sensitivity of saturated aliphatic ketone stretching frequencies, vCO to structure and solvent effects is expressed by a four-term equation vco = 1740 + I(XXX) -0.24 G + 2.10 -3G · I(XXX) The four terms represent: the frequency of the base element (acetone) calculated in the absence of intermolecular interactions; the contribution of intramolecular environment E given by structure parameter I(itXXX) previously established in gas phase; that of the intermolecular environment related to the Allerhand and Schleyer G parameter; that of solvent-solute interactions. This equation covers an experimental range of 78 cm -1 for 192 measurements in four highly diverse solvents (C 6H 14, CC1 4, CH 3CN, CHBr 3) with a standard deviation of 1.6 cm -1; it expresses an overall statistical behavior, but masks individual behaviors. The latter are determined by comparing two characteristic parameters of ketones, a topological parameter I(XXX), and p expressing solvent sensitivity [slope of straight lines ν = f(G)]; they are Interpreted in terms of geometrical effect, variation of valency angles and of conformations.

  10. Etude de l'impact de la valorisation energetique de pneus hors d'usage, dans une cimenterie, sur les emissions gazeuses par modelisation de la dispersion atmospherique

    NASA Astrophysics Data System (ADS)

    Bredin, Nathalie

    La génération incéssante de déchets nécessite le développement de nouvelles technologies, telle que la valorisation énergétique, pour en disposer. Une filière appropriée pour valoriser énergétiquement les déchets est le procédé cimentier. L'industrie du ciment est une des grandes consommatrices d'énergie. La température nécessaire à la préparation du ciment se situe aux environs de 1450°C pour faire réagir la matière première (cru) qui est sous forme poudreuse et constituée principalement de roches calcaires, argileuses, schisteuses,... Les gaz de combustion ont un long temps de résidence dans les fours. De plus, le mode de fonctionnement des fours est responsable d'un effet de lessivage des gaz acides par le cru alcalin. Ces propriétés font du procédé cimentier un bon candidat pour la valorisation énergétique des déchets. Les déchets interessants pour les cimenteries sont, entre autres, les huiles usées, les solvants usés et les pneus usés qui ont un pouvoir calorifique équivalent à celui du charbon. Les rejets à l'atmosphère des cimenteries sont principalement des émissions gazeuses. Ainsi, l'impact de la valorisation de pneus usés sur les émissions gazeuses de la cimenterie Saint-Laurent de Joliette a été étudié, à l'aide de l'outil qu'est la modélisation de la dispersion atmosphérique. Le modèle utilisé ISC-ST2, Industrial Source Complex-Short Term, est de type gaussien. L'analyse des concentrations maximales horaires et moyennes sur différentes périodes de temps (1 heure, 8 heures, ..., 1 an) des émissions gazeuses dans l'air ambiant montre que celles-ci sont en deçà des normes émises par le gouvernement québécois et par la Communauté Urbaine de Montréal. L'étude de la distribution géographique des polluants, d'après les concentrations annuelles, dans un rayon de 5 km autour de la cimenterie montre que le fait d'utiliser des pneus comme combustible de substitution n'a qu'un faible impact sur la concentration des contaminants au niveau du sol. L'étude du modèle gaussien de dispersion a permis de mettre au point un nouvel outil: la corrélation existant entre les concentrations latérales et verticales des polluants dans le panache. Cet outil utilisé pour étudier les schémas de dispersion atmosphérique de Turner en milieu rural, et de Briggs en milieux urbain et rural, montre que, en milieu rural, le schéma de dispersion proposé par Briggs présente une dispersion plus importante que celui de Turner pour les classes neutres et instables et moins importantes pour les classes stables. La comparaison des schémas de Briggs (rural et urbain) confirme que la dispersion en milieu urbain est plus importante qu'en milieu rural.

  11. Rotary-Balance Testing for Aircraft Dynamics (Les Essais sur Balance Rotative pour l’Etude de la Dynamique du Vol de l’Avion)

    DTIC Science & Technology

    1990-01-01

    and gravitational and equal to their counterparts in the dynamic test. A vectorial subtraction of the quantities obtained in the two cases yields the...derivatives. 1 4 Since the aerodynamic characteristics are directional, they should be represented in vectorial form. In Figure 6-17 the motion vectors, AX, Aj...combined vectorially in a 6-DOF flight simulation. 6.2.6 Synopsis 1. The orbital platform, or OPLEC, system is a radically different rotary-balance design

  12. L'ilot du reservoir: etude de voisinage en milieu urbain (The Reservoir Block: A Study of a Neighborhood in an Urban Setting).

    ERIC Educational Resources Information Center

    Rey, Jean-Noel

    1983-01-01

    An analysis of a small neighborhood of Paris looks at its layout and spatial constraints, habitats, symbols, sense of territory, and rhythms and styles of the inhabitants and their roles in the group. The description, including photos, is intended for use in the French language classroom. (MSE)

  13. L'evaluation des programmes d'etudes au Quebec. Etude de cas: Les programmes des techniques d'education en services de garde au Cegep de Saint-Jerome (The Evaluation of Programs of Study in Quebec. Case Study: Child Care Education Programs in CEGEP Saint Jerome).

    ERIC Educational Resources Information Center

    Quebec Commission on the Evaluation of Collegiate Teaching (Quebec).

    Providing a case study of instructional organization and evaluation processes in Quebec's "Colleges d'enseignement general et professionnel" (CEGEPs), this report describes the provincial Commission on the Evaluation of Collegiate Teaching and a 1994 evaluation of "Techniques d'education en services de garde" (TESG), or child…

  14. Revisiting the radio interferometer measurement equation. IV. A generalized tensor formalism

    NASA Astrophysics Data System (ADS)

    Smirnov, O. M.

    2011-07-01

    Context. The radio interferometer measurement equation (RIME), especially in its 2 × 2 form, has provided a comprehensive matrix-based formalism for describing classical radio interferometry and polarimetry, as shown in the previous three papers of this series. However, recent practical and theoretical developments, such as phased array feeds (PAFs), aperture arrays (AAs) and wide-field polarimetry, are exposing limitations of the formalism. Aims: This paper aims to develop a more general formalism that can be used to both clearly define the limitations of the matrix RIME, and to describe observational scenarios that lie outside these limitations. Methods: Some assumptions underlying the matrix RIME are explicated and analysed in detail. To this purpose, an array correlation matrix (ACM) formalism is explored. This proves of limited use; it is shown that matrix algebra is simply not a sufficiently flexible tool for the job. To overcome these limitations, a more general formalism based on tensors and the Einstein notation is proposed and explored both theoretically, and with a view to practical implementations. Results: The tensor formalism elegantly yields generalized RIMEs describing beamforming, mutual coupling, and wide-field polarimetry in one equation. It is shown that under the explicated assumptions, tensor equations reduce to the 2 × 2 RIME. From a practical point of view, some methods for implementing tensor equations in an optimal way are proposed and analysed. Conclusions: The tensor RIME is a powerful means of describing observational scenarios not amenable to the matrix RIME. Even in cases where the latter remains applicable, the tensor formalism can be a valuable tool for understanding the limits of such applicability.

  15. Comparison of observed and simulated spatial patterns of ice microphysical processes in tropical oceanic mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Barnes, Hannah C.; Houze, Robert A.

    2016-07-01

    To equitably compare the spatial pattern of ice microphysical processes produced by three microphysical parameterizations with each other, observations, and theory, simulations of tropical oceanic mesoscale convective systems (MCSs) in the Weather Research and Forecasting (WRF) model were forced to develop the same mesoscale circulations as observations by assimilating radial velocity data from a Doppler radar. The same general layering of microphysical processes was found in observations and simulations with deposition anywhere above the 0°C level, aggregation at and above the 0°C level, melting at and below the 0°C level, and riming near the 0°C level. Thus, this study is consistent with the layered ice microphysical pattern portrayed in previous conceptual models and indicated by dual-polarization radar data. Spatial variability of riming in the simulations suggests that riming in the midlevel inflow is related to convective-scale vertical velocity perturbations. Finally, this study sheds light on limitations of current generally available bulk microphysical parameterizations. In each parameterization, the layers in which aggregation and riming took place were generally too thick and the frequency of riming was generally too high compared to the observations and theory. Additionally, none of the parameterizations produced similar details in every microphysical spatial pattern. Discrepancies in the patterns of microphysical processes between parameterizations likely factor into creating substantial differences in model reflectivity patterns. It is concluded that improved parameterizations of ice-phase microphysics will be essential to obtain reliable, consistent model simulations of tropical oceanic MCSs.

  16. Meteorological conditions during the formation of ice on aircraft

    NASA Technical Reports Server (NTRS)

    Samuels, L T

    1932-01-01

    These are the results of a number of records recently secured from autographic meteorological instruments mounted on airplanes at times when ice formed. Ice is found to collect on an airplane only when the airplane is in some form of visible moisture, such as cloud, fog, mist, rain. etc., and the air temperature is within certain critical limits. Described here are the characteristics of clear ice and rime ice and the specific types of hazards they present to airplanes and lighter than air vehicles. The weather records are classified according to the two general types of formation (clear ice and rime) together with the respective temperatures, relative humidities, clouds, and elevations above ground at which formations occurred. This classification includes 108 cases where rime formed, 43 cases in which clear ice formed, and 4 cases when both rime and clear ice formed during the same flight. It is evident from the above figures that there was a preponderance of rime by the ratio of 2.5 to 1, while in only a few cases both types of ice formation occurred during the same flight.

  17. Comparison of observed and simulated spatial patterns of ice microphysical processes in tropical oceanic mesoscale convective systems: Ice Microphysics in Midlevel Inflow

    SciTech Connect

    Barnes, Hannah C.; Houze, Robert A.

    2016-07-25

    To equitably compare the spatial pattern of ice microphysical processes produced by three microphysical parameterizations with each other, observations, and theory, simulations of tropical oceanic mesoscale convective systems (MCSs) in the Weather Research and Forecasting (WRF) model were forced to develop the same mesoscale circulations as observations by assimilating radial velocity data from a Doppler radar. The same general layering of microphysical processes was found in observations and simulations with deposition anywhere above the 0°C level, aggregation at and above the 0°C level, melting at and below the 0°C level, and riming near the 0°C level. Thus, this study is consistent with the layered ice microphysical pattern portrayed in previous conceptual models and indicated by dual-polarization radar data. Spatial variability of riming in the simulations suggests that riming in the midlevel inflow is related to convective-scale vertical velocity perturbations. Finally, this study sheds light on limitations of current generally available bulk microphysical parameterizations. In each parameterization, the layers in which aggregation and riming took place were generally too thick and the frequency of riming was generally too high compared to the observations and theory. Additionally, none of the parameterizations produced similar details in every microphysical spatial pattern. Discrepancies in the patterns of microphysical processes between parameterizations likely factor into creating substantial differences in model reflectivity patterns. It is concluded that improved parameterizations of ice-phase microphysics will be essential to obtain reliable, consistent model simulations of tropical oceanic MCSs.

  18. 5 W à 255 nm et 15 kHz obtenus par doublage defréquence d'un laser CuHBr dans du BBO

    NASA Astrophysics Data System (ADS)

    Huot, N.; Jonin, C.; Le Harzic, R.; Audouard, E.; Laporte, P.

    2003-06-01

    5.1 W de rayonnement ultra-violet ont été obtenus à 15 kHz par doublage de fréquence de la raie à 510.6 nm d'un laser CuHBr dans deux cristaux de BBO. La qualité de faisceau du rayonnement UV est exprimée par le paramètre M^2 : M_X^2 = 30± 2 et M_Y^2= 24 ± 2. Les deux faisceaux UV issus des deux cristaux de BBO, combinés au point focal d'une lentille, permettent le micro-usinage UV à haute cadence.

  19. Investigation of Cadmium Selenide Photoelectrochemical Cells.

    DTIC Science & Technology

    1980-01-01

    au xinon gmettant un rayonnement de composition spectrale tras comparable A celle de la lumiare solaire correspondant a des conditions MAl (masse de...important. The irradiance at ground level depends on solar elevation and atmospheric conditions. The atmosphere absorbs solar radiation (e.g. by H20, 03...CO2 and other minor constituents) and scatters solar radiation (e.g. Rayleigh and aerosol scattering). The path length through the atmosphere is

  20. Official portrait of STS-65 backup Payload Specialist Jean-Jacques Favier

    NASA Image and Video Library

    1993-09-30

    Official portrait of STS-65 International Microgravity Laboratory 2 (IML-2) backup Payload Specialist Jean-Jacques Favier. Favier is a member of the Centre National D'Etudes Spatiales (CNES), the French space agency.

  1. Wind tunnel evaluation of air-foil performance using simulated ice shapes

    NASA Technical Reports Server (NTRS)

    Bragg, M. B.; Zaguli, R. J.; Gregorek, G. M.

    1982-01-01

    A two-phase wind tunnel test was conducted in the 6 by 9 foot Icing Research Tunnel (IRT) at NASA Lewis Research Center to evaluate the effect of ice on the performance of a full scale general aviation wing. In the first IRT tests, rime and glaze shapes were carefully documented as functions of angle of attack and free stream conditions. Next, simulated ice shapes were constructed for two rime and two glaze shapes and used in the second IRT tunnel entry. The ice shapes and the clean airfoil were tapped to obtain surface pressures and a probe used to measure the wake characteristics. These data were recorded and processed, on-line, with a minicomputer/digital data acquisition system. The effect of both rime and glaze ice on the pressure distribution, Cl, Cd, and Cm are presented.

  2. Additional Study of Water Droplet Median Volume Diameter (MVD) Effects on Ice Shapes

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching; Anderson, David N.

    2005-01-01

    This paper reports the result of an experimental study in the NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the MVD-independent effect identified previously might apply to SLD conditions in rime icing situations. Models were NACA 0012 wing sections with chords of 53.3 and 91.4 cm. Tests were conducted with a nominal airspeed of 77 m/s (150 kt) and a number of MVD's ranging from 15 to 100 m with LWC of 0.5 to 1 g/cu m. In the present study, ice shapes recorded from past studies and recent results at SLD and Appendix-C conditions are reviewed to show that droplet diameter is not important to rime ice shape for MVD of 30 microns or larger, but for less than 30 m drop sizes a rime ice shape transition from convex to wedge to spearhead type ice shape is observed.

  3. Sublexical Inferences in Beginning Reading: Medial Vowel Digraphs as Functional Units of Transfer.

    PubMed

    Savage; Stuart

    1998-05-01

    Two experiments evaluated young children's use of lexical inference. Experiment 1 compared transfer from shared rimes (e.g., "beak"-"peak"), or heads (e.g., "beak"-"bean"), under three conditions: (a) when both clue word pronunciation and orthography were present at transfer; (b) when only the pronunciation of the clue word was given; and (c) when the clue was pretaught. Equivalent transfer occurred in both conditions (a and b) where clue word pronunciations were provided at transfer, but no transfer was found when the clue word was pretaught (condition c). Experiment 2 investigated transfer from three pretaught clue words sharing rimes (e.g., "leak"-"peak"), or vowel digraphs (e.g., "leak"-"bean"). Children demonstrated lexical transfer under these conditions, but improvements were equivalent for vowel and rime analogous words. Results are interpreted in terms of models of vowel transfer. Copyright 1998 Academic Press.

  4. Measurements of local convective heat transfer coefficients on ice accretion shapes

    NASA Technical Reports Server (NTRS)

    Arimilli, R. V.; Keshock, E. G.; Smith, M. E.

    1984-01-01

    The thin-skin heat rate technique was used to determine local convective heat transfer coefficients for four representative ice accretion shapes. The shapes represented three stages of glaze ice formation and one rime ice formation; the ice models had varying degrees of surface roughness. In general, convective heat transfer was higher in regions where the model's surfaces were convex and lower in regions where the surfaces were concave. The effect of roughness was different for the glaze and rime ice shapes. On the glaze ice shapes, roughness increased the maximum Nu by 80 percent, but the other Nu values were virtually unchanged. On the rime ice shape, the Nu numbers near the stagnation point were unchanged. The maximum Nu value increased by 45 percent, and the Nu number downstream of the peak increased by approximately 150 percent.

  5. Une Exception Francaise: Les Grandes Ecoles (A French Exception: The Great Schools).

    ERIC Educational Resources Information Center

    Kimmel, Alain

    1996-01-01

    Examines the role of exceptional schools in France that have produced famous personages such as Charles de Gaulle and Jean-Paul Sartre. The schools reviewed include L'Ecole Nationale d'Administration, L'Ecole Polytechnique, L'Ecole Normale Superieure, L'Ecole des Hautes Etudes Commerciales, Saint-Cyr, and L'Institut d'Etudes Politiques de Paris.…

  6. Une Exception Francaise: Les Grandes Ecoles (A French Exception: The Great Schools).

    ERIC Educational Resources Information Center

    Kimmel, Alain

    1996-01-01

    Examines the role of exceptional schools in France that have produced famous personages such as Charles de Gaulle and Jean-Paul Sartre. The schools reviewed include L'Ecole Nationale d'Administration, L'Ecole Polytechnique, L'Ecole Normale Superieure, L'Ecole des Hautes Etudes Commerciales, Saint-Cyr, and L'Institut d'Etudes Politiques de Paris.…

  7. Multi-Scale Autoregressive Processes

    DTIC Science & Technology

    1989-06-01

    rationnelles et leurs langages," Mas- son 1984, Collection "Etudes et Recherches en Informatique". [12] J.L. DUNAU, "Etude d’une classe de marches...June 1989 LIDS-P-1880 Multi-Scale Autoregressive Processes Michele Basseville’ Albert Benveniste’ Institut de Recherche en Informatique et Systemes...Centre National de la Recherche Scientifique (CNRS) and A.B. is also with Institut National de Recherche en Informatique et en Automatique (INRIA). The

  8. Study of unusual atmospheric icing at Mount Zao, Japan, using the Weather Research and Forecasting model

    NASA Astrophysics Data System (ADS)

    Podolskiy, Evgeny Andreevich; Nygaard, BjøRn Egil Kringlebotn; Nishimura, Kouichi; Makkonen, Lasse; Lozowski, Edward Peter

    2012-06-01

    A mesoscale atmospheric model, the Weather Research and Forecasting model (WRF), was used for a case study that reconstructs mid-spring episodes of rime formation at Mt. Zao, Japan. One particularly interesting and rare form of rime was observed. The formations were feathery, opaque aggregates of granular ice 15-30 cm long, called "shrimp tails" in Japanese. Based on an analysis of model-generated results, we find good quantitative agreement of modeled and observed wind and temperature time series at Jizosancho ropeway station. We identified two icing events (lasting for 36 and 41 h respectively, with surface air temperatures between -6.3° and -0.1°C, relatively constant westerly winds up to 26 m s-1, and maximum cloud liquid water contents (LWC) between 0.72 and 1.05 g m-3). We confirmed that high-resolution modeling (1.1 km grid spacing) was much more accurate than simulations with coarser grids (10 and 3.3 km). The LWC during the formation period of this rare type of icing was estimated for the first time using the WRF model at Mt. Zao, and it was found to be up to several times higher than values previously used in experimental studies. We found that the joint wind speed-air temperature distribution for this type of "tail" rime was more similar to that of a hard rime or glaze, than to a soft rime. We explain the formation of "shrimp tails" by wind impact angle and report previously made laboratory results on its effect on the droplet collision efficiency and the density of rime ice.

  9. ESA is hot on the trail of Geminga

    NASA Astrophysics Data System (ADS)

    close to the neutron star. Geminga’s breathless rotation rate - once every quarter of a second - creates an extraordinary environment in which electrons and positrons, their antimatter counterparts, can be accelerated to extraordinarily high energies. At such energies, they become powerful high-energy gamma-ray producers. Astronomers had assumed that all the electrons would be converted into gamma rays. However, the discovery of the tails proves that some do find escape routes from the maelstrom. “It is astonishing that such energetic electrons succeed in escaping to create these tails,” says Caraveo, “The tail electrons have an energy very near to the maximum energy achievable in the environment of Geminga.” The tails themselves are the bright edges of the three-dimensional shockwave sculpted by Geminga. Such shockwaves are a bit like the wake of a ship travelling across the ocean. Using a computer model, the team has estimated that Geminga is travelling almost directly across our line of sight. Studies of Geminga could not be more important. The majority of known gamma-ray sources in the Universe have yet to be identified with known classes of celestial objects. Some astronomers believe that a sizeable fraction of them may be Geminga-like radio-quiet neutron stars. Certainly, the family of radio-quiet neutron stars, discovered through their X-ray emission, is continuously growing. Currently, about a dozen objects are known but only Geminga has a pair of tails! Note for editors During the search to track down this elusive celestial object, a co-author on the paper, Giovanni Bignami, named Geminga almost 30 years ago. He was Principal Investigator of XMM-Newton's EPIC camera from 1987 to1997 and is now Director of the Centre d'Etude Spatiale des Rayonnements (CESR). Geminga was first glimpsed as a mysterious source of gamma rays, coming from somewhere in the constellation Gemini by NASA's SAS-2 spacecraft in 1973. While searching to pin down its exact location

  10. Influence of consonantal context on the pronunciation of vowels: a comparison of human readers and computational models.

    PubMed

    Treiman, Rebecca; Kessler, Brett; Bick, Suzanne

    2003-05-01

    In two experiments, we found that college students' pronunciations of vowels in nonwords are influenced both by preceding and following consonants. The predominance of rimes in previous studies of reading does not appear to arise because readers are unable to pick up associations that cross the onset-rime boundary, but rather because English has relatively few such associations. Comparisons between people's vowel pronunciations and those produced by various computational models of reading showed that no model provided a good account of human performance on nonwords for which the vowel shows contextual conditioning. Possible directions for improved models are suggested.

  11. Do children need concurrent prompts in order to use lexical analogies in reading?

    PubMed

    Savage, R S

    1997-02-01

    In two experiments, children were taught a word and then given reminders of that word while reading unfamiliar analogous words. Reminders of the pronunciation of taught words facilitated reading of rime analogous words (e.g. beak-peak) over head analogous words (e.g. beak-bean) in Experiment 1, and onset analogous words (e.g. stilt-stem), over medial analogous words (e.g. stilt-milk) in Experiment 2. Importantly, however, privileged improvement for rime and onset analogous words was not evident in the absence of these concurrent prompts. The findings suggest that the analogy model developed by Goswami (1993) may have limited applicability in naturalistic settings.

  12. Les Interferences Semantiques Dans Les Oeuvres D'ahmadou Kourouma et De Mongo Beti: Essai D'etude Comparative [Semantic Interference in the Works of Ahmadou Kourouma and Mongo Beti: Test Comparative Study

    ERIC Educational Resources Information Center

    Tadoum, Jean Paul

    2012-01-01

    This dissertation focuses on the works of two well-known African Francophone novelists, Ahmadou Kourouma from the Ivory Coast and Mongo Beti from Cameroon. The objective of this study is to look at the influences of African oral traditions and analyze the literary transposition of semantic structures from African languages and cultures into the…

  13. Canadian Mathematics Education Study Group = Groupe Canadien d'Etude en Didactique des Mathematiques. Proceedings of the Annual Meeting (25th, Edmonton, Alberta, Canada, May 25-29, 2001).

    ERIC Educational Resources Information Center

    Simmt, Elaine, Ed.; Davis, Brent, Ed.

    This document contains the proceedings of the 2001 annual meeting of the Canadian Mathematics Education Study Group (CMESG) held at the University of Alberta, May 25-39, 2000. The proceedings consist of two plenary lectures, four working groups, five topic sessions, new Ph.D. reports, an AD Hoc Session, and panel discussions. Papers include: (1)…

  14. Etude du transfert de quelques oligo-éléments dans les chaînes trophiques néritiques et estuariennes: Accumulation biologique chez les poissons omnivores et super-carnivores

    NASA Astrophysics Data System (ADS)

    Metayer, C.; Amiard, J.-C.; Amiard-Triquet, C.; Marchand, J.

    1980-06-01

    Five species of fishes (Dicentrarchus labrax, Gobius microps, Stizostedion lucioperca, Gadus luscus, Merlangius merlangus) and their major prey organisms were collected monthly from two stations in the Loire estuary (France). The levels of several trace elements (Cd, Pb, Cu, Zn) in their tissues were determined by means of atomic absorption spectrophotometry. The concentrations of Cd, Pb and Cu were shown to decrease in the highest trophic levels: the relatively highest metal levels were determined in annelids, followed by crustaceans, the lowest levels being encountered in fishes. However, a preferential uptake of Cu was observed in crustaceans. There is no biomagnification for these three metals, the concentrations in preys being generally lower than in predators. For Zn, the highest concentrations were measured in worms and copepods but preys such as shrimps and mysids exhibit values of the same order of magnitude compared to predator fishes.

  15. Telemetre Laser a Onde Entretenue a 10.6 micrometers avec Postdetection non Lineaire: Etude d’un Systeme a un Laser (A 10.6 micrometer Amplitude Modulated Telemeter Laser with Nonlinear Postdetection: Study of a Single Laser System),

    DTIC Science & Technology

    1981-04-01

    polarisation ’Is" (lames X/2 et CaF 2enlev~es). Deux lentilles L 1et L2(Ge, f = 20 cm) permettent d’injecter le faisceau laser (w =2.5 mm) dans le cristal...CLASSIFIE 9 Le faisceau modul6 est envoy6 sur la cible qui le retourne au d~tecteur a travers une lentille L 3 (ZnSe, f = 12.5 cm,, diam. = 5 cm) ou L 4 (Ge...modulateur, mesur~e a X = 10.6 u~m, est la suivante: Ttotale )j.3 TX4 = .8 o1 085, T CdTe .5 sans lentilles ). 4.3 Systame de d6tection et de

  16. Proceedings of the 2007 Annual Meeting of the Canadian Mathematics Education Study Group = Actes de la Rencontre Annuelle 2007 du Groupe Canadien d'Etude en Didactique des Mathematiques (31st, Fredricton, New Brunswick, Canada, Jun 8-12, 2007)

    ERIC Educational Resources Information Center

    Liljedahl, Peter, Ed.

    2008-01-01

    This submission contains the Proceedings of the 2007 Annual Meeting of the Canadian Mathematics Education Study Group (CMESG), held at the University of New Brunswick in Fredricton, New Brunswick. The CMESG is a group of mathematicians and mathematics educators who meet annually to discuss mathematics education issues at all levels of learning.…

  17. Etude comparative des conditions environnementales potentiellement limitantes dans l'etablissement d'une espece aquatique envahissante Clona intestinalis (Linnaeus, 1767) dans deux systemes de bassins versants a l'ile-du Prince-Edouard, Canada

    NASA Astrophysics Data System (ADS)

    Mclaughlin, Janelle

    Aquatic invasive species are a growing global problem. Since the late 1990s, the province of Prince Edward Island (PEI), located on the east coast of Canada, has seen the introduction and the establishment of several species of tunicate. Shortly after their introduction into new aquatic systems such as the Brudenell and Montague rivers, tunicate population exploded to extremely high levels which have had significant impacts on native species populations, the fisheries and aquaculture industries and on the economy of local communities. Brudenell and Montague rivers are located southeast of the province. Comparatively, the aquatic system of Orwell Bay, which is also located in this area, is an exception to the successful establishment of tunicates, despite several successive unintentional introductions. The objective of this research is to identify and understand the main key factors that could potentially limit the establishment of a tunicate species in PEI. This study is based on a comparative approach between the two aquatic systems previously mentioned. The results of this research shows that the Orwell Bay system is characterized by a slightly higher percentage of terrestrial areas with potential soil loss, a shorter water renewal time, a shallower aquatic area, a higher turbidity level, a slightly lower salinity and a slightly higher temperature than the Brudenell and Montague rivers system. One of the environmental variables that showed a significant difference between the two systems in the analysis is turbidity. This study also examines the relationship between different turbidity levels, in terms of suspended inorganic matter, and its potential role in the establishment of the invasive tunicate C. intestinalis. Two laboratory experiments were conducted to evaluate the effect of suspended inorganic matter on primary stages of this species of tunicate. The results show a significant negative effect at higher suspended inorganic matter levels on fertilization rate, larval establishment and survival of juvenile tunicates. All these elements can potentially be key factors on limiting the establishment of a population of C. intestinalis in the Orwell Bay aquatic system. Keywords: Invasive species, watershed, biogeography, tunicate, Ciona intestinalis, universal soil loss equation, hydrodynamic modeling, correspondence analysis, turbidity, environmental tolerance.

  18. Etude séro-epidémiologique de trois infections sexuellement transmissibles (Chlamydia Trachomatis, Hépatite B, Syphilis): cas de l’Hôpital de District de Nkoldongo à Yaoundé

    PubMed Central

    Essome, Marie Chantal Ngonde; Nsawir, Bonglaisin Julius; Nana, Rodrigue Dongang; Molu, Patrick; Mohamadou, Mansour

    2016-01-01

    Introduction Les infections sexuellement transmissibles sévissent toujours dans les pays en voie de développement et particulièrement au Cameroun. Le but de notre étude est de déterminer la distribution des infections sexuellement transmissibles suivantes: l’hépatite virale B, le Chlamydia trachomatis et de la syphilis dans une population de femmes venant consulter spontanément à l’Hôpital de District de Nkoldongo à Yaoundé, d’évaluer d’éventuelles coïnfections entre ces trois affections et de ressortir les connaissances de ces femmes sur leur mode de transmission sexuelle. Méthodes Notre étude prospective et descriptive a porté sur 182 femmes dont l’âge variait entre 18 et 48 ans. Les femmes ont été testées sérologiquement pour le Chlamydia trachomatis par une méthode ELISA (kit des laboratoires General Biological Corp). L’hépatite virale B a été dépistée par une méthode immunochromatographique (kit des laboratoires Human) et la syphilis par une méthode d’agglutination en ce qui concerne le RPR (Kit des laboratoires Biocentric) et le TPHA (kit des laboratoires Human). Résultats Nos résultats ont montré que: la distribution du Chlamydia trachomatis, de l’hépatite virale B et la syphilis a été respectivement de 22,52%, 4,39%, 0,54%.De plus, nous avons observé une coinfection Chlamydia trachomatis hépatite virale B avec un taux de 2,74%. Par ailleurs la réinfection au Chlamydia trachomatis a été rencontrée dans 4,94% de cas. S’agissant du mode de transmission de ces affections 67,57% et 70,87% de femmes ne connaissaient pas la voie de transmission sexuelle pour le Chlamydia trachomatis et pour l’hépatite virale B respectivement, tandis que 91,2 % des femmes connaissaient la voie de transmission sexuelle pour la syphilis. Conclusion Le diagnostic d’une infection à Chlamydia trachomatis chez une patiente doit susciter le dépistage de l’hépatite virale B. Introduction Sexually transmitted infections are still frequent in developing countries and particularly in Cameroon. The aim of this study was to determine the distribution of the following sexually transmitted infections: viral hepatitis B, Chlamydia trachomatis and syphilis in a population of women spontaneously visiting the Nkoldongo District Hospital in Yaoundé as well as to evaluate possible co-infections among these three conditions and to bring out women’s prior knowledge of how sexual transmission occurs. Methods We conducted a prospective and descriptive study including 182 women aged between 18 and 48 years. These women underwent serologic testing for Chlamydia trachomatis with ELISA (General Biological Corp laboratory test kit. Hepatitis B virus was detected using immunochromatographic method (Human laboratory kit) while syphilis was detected using RPR agglutination (Biocentric Laboratories kit )and TPHA agglutination (Human laboratory kit) method. Results Our results showed that the distribution of Chlamydia trachomatis, viral hepatitis B and syphilis was 22.52%, 4.39%, 0.54% respectively. Moreover, we reported a Chlamydia trachomatis and Viral hepatitis B coinfection rate of 2.74%. In addition, Chlamydia trachomatis reinfection was detected in 4.94% of cases. Regarding the mode of transmission of these infections, 67.57% and 70.87% of women didn’t know how Chlamydia trachomatis and viral hepatitis sexual transmission could occur respectively, while 91.2% of women knew how was syphilis spread. Conclusion The diagnosis of chlamydia trachomatis infection should prompt screening for viral hepatitis B. PMID:28293360

  19. Etude du faible poids de naissance associé à l’âge maternel et la parité dans une population couple mère-enfant suivi à Lubumbashi

    PubMed Central

    Luhete, Prosper Kakudji; Mukuku, Olivier; Kayamba, Prosper Kalenga Muenze

    2015-01-01

    Introduction Evaluer l'influence de l’âge maternel et de la parité sur la naissance d'un faible poids de naissance (FPN) à Lubumbashi. Méthodes Il s'agit d'une étude basée sur une analyse documentaire des dossiers médicaux des accouchées enregistrées dans les maternités des 10 hôpitaux généraux de référence (HGR) de la ville de Lubumbashi en République Démocratique du Congo entre le 1er décembre 2013 et le 31 mars 2014. Ces accouchées ont été réparties en deux groupes, en fonction du poids de naissance de leurs enfants: groupe I (femmes ayant accouché de nouveau-nés vivants dont le poids était inférieur à 2500 grammes) et groupe II (femmes ayant accouché de nouveau-nés vivants dont le poids était supérieur ou égal à 2500 grammes). Il s'agissait dans tous les cas de grossesses monofoetales âgées de 28 semaines ou plus. L’âge maternel et la parité ont été étudiés et comparés dans les deux groupes. Les données ont été analysées à l'aide des logiciels Épi info version 7.0 et SPSS version 19. Les différences étaient jugées significatives pour un seuil p < 0,05. Résultats La prévalence du FPN chez les nouveau-nés issus de ces accouchées était ainsi de 6,4% (71/1112). En analyse univariée, les femmes d’âge < 20 ans présentent un risque multiplié par 2,47 fois d'avoir un nouveau-né de FPN comparativement à celles de ≥20 ans (OR = 2,47; IC95%: 1,26-4,78) et celui pour les primipares d'avoir un enfant de FPN est 2,3 fois supérieur à celui de multipares (OR = 2,32; IC95%: 1,34-3,99). En faisant la régression logistique, nous avons observé que seule la parité est significativement corrélée au poids de naissance (OR ajusté = 2,61; IC95%: 1,43-4,74). Conclusion L’étude que nous avons menée montre que le taux de FPN diminue considérablement avec l’âge de la mère à partir de 20 ans et la multiparité. PMID:26161169

  20. Une epreuve orale de francais en fin d'etudes de gestion. Construction et implications pedagogiques (An Oral French Exam at the End of a Marketing Program. Construction and Pedagogical Implications).

    ERIC Educational Resources Information Center

    Crawshaw, Robert H.

    1984-01-01

    An oral language test administered at the end of a four-year program combining business administration and French is described. The test consists of the formal presentation of a report including numbers, graphics, and text, a discussion of a theoretical issue, and interview. (MSE)

  1. A Survey of Serious Aircraft Accidents Involving Fatigue Fracture. Volume 2. Rotary-Wing Aircraft (Etude sur des Accidents Importants d’Avions du aux Effets des Fractures de Fatigue. Volume 2. Effets sur des Helicopteres).

    DTIC Science & Technology

    1983-04-01

    accidents occurring from a particular form of crack initiation (for example "fretting"), look up the cross-reference list in Table 4, and use the...tail rotor problems (7 per year), and failures in the main rotor system (4 per year). 4.4 Initiation Sites The fatigue- crack initiation sites for the...sufficient action taken in order to arrest the problem. 5. The five most common initiation sites for fatigue cracks that have resulted in rotary-wing

  2. A Survey of Serious Aircraft Accidents Involving Fatigue Fracture. Volume 1. Fixed-Wing Aircraft (Etude sur des Accidents Importants d’Avions du aux Effets des Fractures de Fatigue. Volume 1. Effets sur des Avions).

    DTIC Science & Technology

    1983-04-01

    E276 F11 F96 7100 F108 F113 F120 F166 F193 F215 G306 G313 G332 G362 G376 G421 G523 G531 G536 NICARAGUA E19 G280 NIGERIA A47 NORTH YEMEN E404 PAKISTAN...West Chester, Pa. USA. Left main gear attach bolt. Ref: NTSB file 3-3287. G280 Boeing 727 28 Sep 70 0 S Las Mercedes Airport, Managua, Nicaragua...17 Sep 75 0 S Tokyo, Japan. 727-200 Welding parts (Ps4) of combustion chamber outer case. Origin: pitting corrosion. Landing Gear G280 Boeing 727 28

  3. Etude de la Recharge de l’Accumulateur Plomb-Acide Red Camel Entre +20 C et -30 C (A Study of the Rechargeability of the Red Camel Lead-Acid Battery between +20 C and -30 C).

    DTIC Science & Technology

    1983-10-01

    Pour un voltage limite imposg de 14.3 V et une dur~e de charge de 7 heures, les rendements en courant (Rc) et en gnergie fi1ectrique (Re), calcul~s en...pour le d~marrage des v~hicules A moteur . Cependant en dega de -20*C, on assiste A une diminution importante des performances en dicharge rapide...rficup~ration de la capaciti dana le calcul des rendements en courant et en finergie filectrique. CONDUITE DES ESSAIS Lors de toul lea easais, le courant

  4. Fate of a volatile chlorinated solvent in indoor aquatic microcosms: sublethal and static exposure to [14C]dichloromethane. Groupe pour l'Etude du Devenir de Xénobiotiques dans l'Environnement (GEDEXE).

    PubMed

    Thiébaud, H; Merlin, G; Capovilla, M P; Blake, G

    1994-06-01

    The goal of this work was to study the fate of dichloromethane in indoor aquatic microcosms after a sublethal and static exposure to simulate the accidental contamination of a lenitic ecosystem such as littoral lake zone or a pond. This kind of ecosystem is characterized by high productive capacity and rich biocoenose, and are usually first affected by acute or chronic pollution. Microcosms containing immersed bryophytes (Fontinalis antipyretica), macrophytes (Lemna minor, Groenlendia densa, Elodea canadensis), molluscs (Physa fontinalis), crustaceans (Daphnia magna), and unicellular green algae (Scenedesmus subspicatus) were contaminated with sublethal concentrations of dichloromethane or [14C]dichloromethane. The initial mean concentration was 9.9 +/- 3.7 microM. The mean concentration exposure for organisms was 4.5 +/- 1.5 microM. The fate of 14C radioactivity was monitored by measuring the radioactivity of the sediment, water, macro- and microorganism, and atmospheric compartments. Radioactivity in the water disappeared quickly from the microcosms, most likely as [14C]dichloromethane (t1/2 = 5.31 +/- 0.41 days). At the end of the experiments, radioactivity was mainly located in the atmosphere, with traces remaining in the biomass. Under static conditions, the bioaccumulation of 14C radioactivity from the radiolabeled dichloromethane was negligible.

  5. Proceedings of the 2003 Annual Meeting of the Canadian Mathematics Education Study Group = Actes de la Rencontre Annuelle 2003 du Groupe Canadien d'Etude en Didactique des Mathematiques (27th, Wolfville, Nova Scotia, Canada, May 30-June 3, 2003)

    ERIC Educational Resources Information Center

    Simmt, Elaine, Ed.; Davis, Brent, Ed.

    2004-01-01

    This submission contains the Proceedings of the 2003 Annual Meeting of the Canadian Mathematics Education Study Group (CMESG), held at Acadia University in Wolfville, Nova Scotia. The CMESG is a group of mathematicians and mathematics educators who meet annually to discuss mathematics education issues at all levels of learning. The aims of the…

  6. La Lecon d'intonation de Simone de Beauvoir, etude d'intonation declarative comparee (The Lesson on Intonation of Simone de Beauvoir: A Comparative Study of Declarative Intonation).

    ERIC Educational Resources Information Center

    Delattre, Pierre

    1961-01-01

    Spectrographic analysis of two lectures given without notes by Simone de Beauvoir and Margaret Mead allow detailed specification of three forms of intonation characteristic of declarative sentences in English and French. Discussion of the objectives, of analysis procedures, and of results of the study which elaborate on intonational differences…

  7. Proceedings of the 2002 Annual Meeting of the Canadian Mathematics Education Study Group = Actes de la Rencontre Annuelle 2002 du Groupe Canadien d'Etude en Didactique des Mathematiques (26th, Kingston, Ontario, Canada, May 24-28, 2002)

    ERIC Educational Resources Information Center

    Simmt, Elaine, Ed.; Davis, Brent, Ed.

    2003-01-01

    This submission contains the Proceedings of the 2002 Annual Meeting of the Canadian Mathematics Education Study Group (CMESG), held at Queen's University in Kingston, Ontario. The CMESG is a group of mathematicians and mathematics educators who meet annually to discuss mathematics education issues at all levels of learning. The aims of the Study…

  8. Une epreuve orale de francais en fin d'etudes de gestion. Construction et implications pedagogiques (An Oral French Exam at the End of a Marketing Program. Construction and Pedagogical Implications).

    ERIC Educational Resources Information Center

    Crawshaw, Robert H.

    1984-01-01

    An oral language test administered at the end of a four-year program combining business administration and French is described. The test consists of the formal presentation of a report including numbers, graphics, and text, a discussion of a theoretical issue, and interview. (MSE)

  9. Etude et simulation du protocole TTEthernet sur un sous-systeme de gestion de vols et adaptation de la planification des tâches a des fins de simulation

    NASA Astrophysics Data System (ADS)

    Abidi, Dhafer

    TTEthernet is a deterministic network technology that makes enhancements to Layer 2 Quality-of-Service (QoS) for Ethernet. The components that implement its services enrich the Ethernet functionality with distributed fault-tolerant synchronization, robust temporal partitioning bandwidth and synchronous communication with fixed latency and low jitter. TTEthernet services can facilitate the design of scalable, robust, less complex distributed systems and architectures tolerant to faults. Simulation is nowadays an essential step in critical systems design process and represents a valuable support for validation and performance evaluation. CoRE4INET is a project bringing together all TTEthernet simulation models currently available. It is based on the extension of models of OMNeT ++ INET framework. Our objective is to study and simulate the TTEthernet protocol on a flight management subsystem (FMS). The idea is to use CoRE4INET to design the simulation model of the target system. The problem is that CoRE4INET does not offer a task scheduling tool for TTEthernet network. To overcome this problem we propose an adaptation for simulation purposes of a task scheduling approach based on formal specification of network constraints. The use of Yices solver allowed the translation of the formal specification into an executable program to generate the desired transmission plan. A case study allowed us at the end to assess the impact of the arrangement of Time-Triggered frames offsets on the performance of each type of the system traffic.

  10. Canadian Mathematics Education Study Group = Groupe Canadien d'Etude en Didactique des Mathematiques. Proceedings of the Annual Meeting (24th, Montreal, Quebec, Canada, May 26-30, 2000).

    ERIC Educational Resources Information Center

    Simmt, Elaine, Ed.; Davis, Brent, Ed.; McLoughlin, John Grant, Ed.

    This document contains the proceedings of the annual meeting of the Canadian Mathematics Education Study Group (CMESG) held at the University of Quebec in Montreal, Canada, May 26-30, 2000. The proceedings consist of two plenary lectures, five working groups, four topic sessions, new Ph.D. reports, and panel discussions. Papers include: (1)…

  11. Etude morphosyntaxique du parler acadien de la Baie Sainte-Marie, Nouvelle-Ecosse, Canada (A Morphosyntactic Study of the Acadian Dialect of Baie Sainte-Marie, Nova Scotia, Canada). Publication B.

    ERIC Educational Resources Information Center

    Gesner, B. Edward

    A study was conducted of the Baie Sainte-Marie Acadian dialect, a particular form of the French language derived from the French spoken in France during the 16th and 17th centuries. The purpose of this study was to analyze and explain a certain number of morphosyntactic deviations from standard French, from both a synchronic and a diachronic…

  12. Extrahepatic manifestations associated with hepatitis C virus infection. A prospective multicenter study of 321 patients. The GERMIVIC. Groupe d'Etude et de Recherche en Medecine Interne et Maladies Infectieuses sur le Virus de l'Hepatite C.

    PubMed

    Cacoub, P; Renou, C; Rosenthal, E; Cohen, P; Loury, I; Loustaud-Ratti, V; Yamamoto, A M; Camproux, A C; Hausfater, P; Musset, L; Veyssier, P; Raguin, G; Piette, J C

    2000-01-01

    From January 1996 to January 1997, 321 patients with an average age of 46 +/- 16 years and chronically infected with hepatitis C virus (HCV) were prospectively enrolled in a study designed to determine the prevalence of extrahepatic manifestations associated with HCV infection in a large cohort of HCV patients, to identify associations between clinical and biologic manifestations, and to compare the results obtained in human immunodeficiency virus (HIV)-positive versus HIV-negative subsets. In a cross-sectional study, clinical extrahepatic manifestations, viral coinfections with HIV and/or hepatitis B virus, connective tissue diseases, and a wide panel of autoantibodies were assessed. Thirty-eight percent (122/321) of patients presented at least 1 clinical extrahepatic manifestation including arthralgia (60/321, 19%), skin manifestations (55/321, 17%), xerostomia (40/321, 12%), xerophthalmia (32/321, 10%), and sensory neuropathy (28/321, 9%). Main biologic abnormalities were mixed cryoglobulins (110/196, 56%), thrombocytopenia (50/291, 17%), and the presence of the following autoantibodies: antinuclear (123/302, 41%), rheumatoid factor (107/280, 38%), anticardiolipin (79/298, 27%), antithyroglobulin (36/287, 13%) and antismooth muscle cell (27/288, 9%). At least 1 autoantibody was present in 210/302 (70%) of sera. By multivariate logistic regression analysis, 4 parameters were significantly associated with cryoglobulin positivity: systemic vasculitis (p = 0.01, odds ratio OR[ = 17.3), HIV positivity (p = 0.0006, OR = 10.2), rheumatoid factor positivity (p = 0.01, OR = 2.8), and sicca syndrome (p = 0.03, OR = 0.27). A definite connective tissue disease was noted in 44 patients (14%), mainly symptomatic mixed cryoglobulinemia and systemic vasculitis, HIV coinfection (23%) was associated with 3 parameters: anticardiolipin (p = 0.003, OR = 4.18), thrombocytopenia (p = 0.01, OR = 3.56), and arthralgia or myalgia (p = 0.017, OR = 0.23). HIV-positive patients presented more severe histologic lesions (p = 0.0004). Extrahepatic clinical manifestations in HCV patients involve primarily the skin and joints. The most frequent immunologic abnormalities include mixed cryoglobulins, rheumatoid factor, antinuclear, anticardiolipin, and antithyroglobulin antibodies. Cryoglobulin positivity is associated with systemic vasculitis and rheumatoid factor and HIV positivity. HIV coinfection is associated with arthralgia or myalgia, anticardiolipin antibodies, and thrombocytopenia.

  13. Le langage des "gendarmes" et des "voleurs": etude comparative du vocabulaire de la pegre et de la police en francais et en anglais ("Cops" and "Robbers" Language: A Comparative Study of the Underworld and Police Vocabulary of French and English).

    ERIC Educational Resources Information Center

    Brunet, Jean-Paul

    1981-01-01

    Discusses the meaning and origins of the word "argot," its cryptic character, and its function in a closed social group, focusing on a comparative description of the French and Anglo-American vocabulary of the underworld and the police. Comments on shared traits and provides an insight into the differences. (MES)

  14. Exploratory Field Investigation of Ground Penetration by Aerial Planting-Darts and Subsequent Germinant Survival (Etudes Preliminaires sur le Terrain de la Penetration et de la Survie Ulterieure de Semis en Tubes (DARDS) Plantes par Aeronef),

    DTIC Science & Technology

    1983-02-01

    weeks before the field tests, unstratified seeds were used and the basic soil-mix was oven-dried to reduce the moisture content to less than 5 per...associated with various ranges of fin exposure are somewhat arbitrary, since they pre-suppose a relationship between penetration and the prospects for seed ... scarification greatly reduces the number of losses which occur when darts strike obstacles. The number of cases of inadequate penetration falls from 53 per

  15. Etude théorique des paramètres principaux réglant la sensibilité des capteurs d'accélération à cristal de quartz

    NASA Astrophysics Data System (ADS)

    Delaite, R.; Aïch, Y.

    1994-10-01

    A theoretical analysis of quartz accelerometers is performed to determine their optimal mechanical and sensitivity performances. A general analytical model is used to investigate the parameters and their effects on the sensitivity of these sensors. The analysis of physical characteristics shows that feasibility and performances depend on three factors such as dimensions of the quartz plate, quantity of holders located at the crystal edge and location of these holders with respect to the crystal's crystallographic reference. This study is applied to various design sensors with different supporting quartz crystal. The conditions on parameters are given to achieve optimum performances. Une étude théorique de la sensibilité des capteurs d'accélération à cristal de quartz est présentée. Son but est d'optimiser les performances mécaniques et métrologiques de ces capteurs. Les paramètres sensibles sont mis en évidence. L'analyse des caractéristiques physiques démontre que la faisabilité et les performances des accéléromètres à quartz dépendent, pour une coupe donnée du cristal, de trois facteurs : les dimensions de la lame de quartz, le nombre de liaisons à la périphérie du cristal et la position de ces liaisons par rapport à la référence cristallographique. L'étude est appliquée aux cas des capteurs bipodes, multipodes et monopodes. Pour chaque type de capteur, les valeurs des paramètres sensibles correspondant aux performances optimales sont précisées.

  16. Etude de facteurs de risque de la transmission du VIH de la mère à l'enfant dans la stratégie « option A » à Lubumbashi, République Démocratique du Congo

    PubMed Central

    Ngwej, Dieudonné Tshikwej; Mukuku, Olivier; Mudekereza, Rachel; Karaj, Eugénie; Odimba, Etienne Bwana Fwamba; Luboya, Oscar Numbi; Kakoma, Jean-Baptiste Sakatolo; Wembonyama, Stanis Okitotshio

    2015-01-01

    Introduction L'infection à VIH chez la femme enceinte a pour principal risque la contamination du nouveau-né. L'objectif est de déterminer le taux de transmission du VIH de la mère à l'enfant (TME) dans la ville de Lubumbashi et en évaluer les facteurs de risque. Méthodes Il s'agissait d'une étude prospective transversale à visée analytique de 157 accouchées séropositives au VIH et de leurs enfants dans 12 structures sanitaires de Lubumbashi (RDCongo) du 1er octobre 2012 au 31 décembre 2013. Les paramètres sociodémographiques, cliniques et les données relatives aux activités de PTME du VIH ont été étudiés. Les statistiques usuelles ont été utilisées pour analyser les résultats. Le seuil de significativité a été fixé à une valeur de p < 0,05. Résultats Le taux de transmission verticale du VIH était de 12,7% (20/157). Il n'y avait pas d'association significative entre les caractéristiques sociodémographiques maternelles telles que l’âge, la parité, le niveau d’étude, la profession et l’état-civil et la TME (p>0,05). La transmission verticale du VIH était significativement associée aux facteurs suivants: le stade clinique 3 de l'OMS (OR=5,18 (1,5-18,1)), la présence d'infection opportuniste (OR=8,7 (2,7-27,8)), le dépistage lors de l'accouchement (OR=6,3 (1,0-39,0)) ou au cours de l'allaitement (OR=7,1 (1,1-76,7)), au taux de CD4 maternel <350/mm3 (OR=2,9 (1,1-7,7)), l'absence de thérapie antirétrovirale chez la mère (OR=19,9 (4,8-81,9)), la naissance avant terme (OR=4,7 (1,4-16,0)), la rupture prématurée de membranes (OR=45,0 (7,4-454,6)), le faible poids de naissance (OR=5,6 (1,9-16,7)), la notion de réanimation néonatale (OR=12,4 (3,8-40,1)), la non administration de la névirapine à la naissance (OR=26,4 (7,6-92,3)) et l'alimentation mixte (OR=12,6 (1,3-115,9)). Le sexe du nourrisson et le mode d'accouchement n’étaient pas non plus associés à la transmission verticale du VIH (p>0,05). Conclusion Le taux de TME du VIH demeure fort élevé à Lubumbashi comme dans la plupart de pays en développement où les nouveau-nés continuent d’être infectés par le VIH de manière verticale alors que certains facteurs de transmission sont tout à fait souvent évitables. La réduction de cette transmission passe par une amélioration du système de suivi des grossesses dans notre milieu. PMID:26600917

  17. Etudes des verres du pseudo-ternaire La 2S 3Bi 2S 3Ga 2S 3, en relation avec le diagramme de phases et la spectroscopie infra-rouge

    NASA Astrophysics Data System (ADS)

    Ecrepont, C.; Guittard, M.; Barnier, S.; Loireau-Lozac'h, A. M.; Palazzi, M.; Julien, C.; Massot, M.

    1992-04-01

    The phase diagram of the La 2S 3Ga 2S 3Bi 2S 3 ternary system is described. DTA measurements have been carried out on a large variety of glass, and the glass formation domain has been defined with the investigation of Tg, Tc, and the endothermic peaks. Infrared absorption spectra have been studied. The vibrational assignment is discussed in relation to the composition of the glass.

  18. Enquetes sur Differents Aspects de la Vie Sociale a Rennes et en Bretagne. Rapports des Groupes d'Etudes (Inquiries into Various Aspects of the Social Life at Rennes and in Brittany. Reports of Study Groups).

    ERIC Educational Resources Information Center

    Saint Catherine Coll., St. Paul, Minn.

    This collection of reports on French civilization represents the efforts of several teams of students participating in the 1964 NDEA summer institute at Rennes, France. As a partial requirement for the civilization course, the groups submitted field study reports of the cultural life at Rennes and Brittany including: (1) environment and…

  19. Proceedings of the 2005 Annual Meeting of the Canadian Mathematics Education Study Group = Actes de la Rencontre Annuelle 2005 du Groupe Canadien d'Etude en Didactique des Mathematiques (29th, Ottawa, Ontario, Canada, May 27-31, 2005)

    ERIC Educational Resources Information Center

    Liljedahl, Peter, Ed.

    2006-01-01

    This submission contains the Proceedings of the 2005 Annual Meeting of the Canadian Mathematics Education Study Group (CMESG), held at the University of Ottawa in Ottawa, Ontario. The CMESG is a group of mathematicians and mathematics educators who meet annually to discuss mathematics education issues at all levels of learning. The aims of the…

  20. Methode de calcul a N-corps basee sur la G0W0: Etude du couplage electron-phonon dans le C60 et developpement d'une approche acceleree pour materiaux organiques

    NASA Astrophysics Data System (ADS)

    Laflamme Janssen, Jonathan

    This thesis studies the limitations of density functional theory. These limits are explored in the context of a traditional implementation using a plane waves basis set. First, we investigate the limit of the size of the systems that can be treated. Cutting edge methods that assess these limitations are then used to simulate nanoscale systems. More specifically, the grafting of bromophenyl molecules on the sidewall of carbon nanotubes is studied with these methods, as a better understanding of this procedure could have substantial impact on the electronic industry. Second, the limitations of the precision of density functional theory are explored. We begin with a quantitative study of the uncertainty of this method for the case of electron-phonon coupling calculations and find it to be substantially higher than what is widely presumed in the literature. The uncertainty on electronphonon coupling calculations is then explored within the G0W0 method, which is found to be a substantially more precise alternative. However, this method has the drawback of being severely limitated in the size of systems that can be computed. In the following, theoretical solutions to overcome these limitations are developed and presented. The increased performance and precision of the resulting implementation opens new possibilities for the study and design of materials, such as superconductors, polymers for organic photovoltaics and semiconductors. Keywords: Condensed matter physics, ab initio calculations, density functional theory, nanotechnology, carbon nanotubes, many-body perturbation theory, G0W0 method..

  1. Etude du revenu de l'acier z 10 CDNbV0902 (type 9% Cr, 2% Mo + Nb,V) envisage pour la realisation de certains composants des reacteurs a neutrons rapides

    NASA Astrophysics Data System (ADS)

    Pelletier, M.; Vilar, R. M.; Cizeron, G.

    1982-02-01

    Après trempe depuis 1100°C, l'acier étudié est formé de ferrite stable à haute température et de martensite. Au cours de revenus anisothermes, la phase martensitique est le siège de la précipitation successive de carbures des types M 3C, M 7C 3 et M 2C, ces deux derniers étant responsables d'un durcissement secondaire significatif. Aux températures plus élevées, ces carbures se dissolvent tandis qu'apparaissent des carbures des types M 23C 6 et M 6C. La phase ferritique initialement sursaturée est, par ailleurs, le siège d'une précipitation de carbures des types M 2C et M 23C 6.

  2. Etude experimentale de l'effet de rochet de traction-torsion d'un acier inoxydable 17-12 Mo-SPH, de 20 A 650° C

    NASA Astrophysics Data System (ADS)

    Delobelle, P.

    1989-08-01

    Le but du presént article est 1'étude expérimentale du phénomèna de rochet 2D de traction-torsion, essai non proportionnel particulièrement riche en informations et très peu étudié. La séquence expérimentale consiste en l'application d'une faible contrainte secondaire de traction et en la superposition d'une déformation cyclique, d'amplitude maximale constante, pour une vitesse et une isotherme fixées. Nous avons étudie 1'ensemble des caractéristiques de ce chargement, à savoir, l'effet de la contrainte axiale σ zz, de l'amplitude de la déformation {Δɛ zθT}/{2}, de la vitesse de déformation ge zθT et de la température T. On identifie des mécanismes d'interaction dislocations-défauts ponctuels pour le domaine des températures intermédiaires. En conclusion, ce type d'essai réalise une synthèse des difficultés que l'on peut rencontrer lors de la modélisation, presque tous les effets (en dehors de l'anisotropie initiate) étant présents et intimement liés: comportement viscoplastique, effet de normalité, de mémoire évanescente de l'histoire antérieure, du temps, de la température, de la configuration des défauts ponctuels, de contrainte moyenne et enfin, à plus haute température, de précipitation à longue distance.

  3. Etude de la migration des interstitiels dans des austenites Fe, Cr (18), Ni (14) pures et industrielles par irradiation dans un microscope a tres haute tension: Role du carbone et du titane

    NASA Astrophysics Data System (ADS)

    Housseau, N.; Pelissier, J.

    1983-12-01

    Nous avons étudié le rôle des impurtés (C ou Ti) dans la condensation et la migration des défauts interstitiels. Les échantillons étudiés sont des aciers austénitiques: (a) acier de synthèse de haute pureté (Cr 18, Ni 14, Fe) avec ou sans carbone; (b) acier industriel avec C (800 ppm) ou Ti (0,45%). Les échantillons ont été irradiés dans un microscope à très haute tension aux doses allant de 10 -4 jusqu'à 10 -1 dpa aux températures de 300°C à 400°C. Dans de telles conditions les défauts observés sont des boucles interstitielles. L'étude de la variation de l'épaisseur de la zone dénudée près du bord de la lame mince en fonction de la température nous a permis d'évaluer l'énergie de migration effective de l'interstitiel dans ces alliages. Dans l'austénite de synthèse carburée ou non sa valeur est de 0.8 eV. Dans l'acier industriel au titane carburé ou non on obtient 2.0 eV. Nous n'avons pas observé d'effet lié au carbone. L'examen de la densité de boucles à saturation dans les divers aciers suggère une forte énergie de liaison interstitiel-titane. Cette énergie de liaison, si l'ont admet que le titane est la seule impureté agissante du système, peut être estimée à 1.2 eV.

  4. Etude analytique et numérique de la réponse en vibration à hautes fréquences d'éprouvettes de fatigue vibratoire des métaux. Application aux aciers

    NASA Astrophysics Data System (ADS)

    Ben Aich, A.; El Kihel, B.; Kifani, A.; Sahban, F.

    1994-07-01

    In the present paper, the so-called " ultrasonic fatigue " or fatigue at very high frequency has been studied in the materials elastic behaviour case while neglecting the thermal effects that influence the mechanical fields. The determination of mechanical fields and specimen resonance length has been done both analytically and numerically. The numerical method used for this calculation is the finite element method (FEM). Martensitic steel " Soleil A2 " and austenitic steel " ICL 472 BC "