Traitement de texte et stratégies rédactionnelles

The objective of this experimental observation is to show how the use of a standard word processor changes the writing strategies devised by advanced users during the production of short texts. Empirical research has indicated that word processors, in fact, have a negative impact on writing strategies. Analysis of the conditions under which "man-machine" dialogue takes place, has shown that screen size and linear management both have an effect on writing. Before determining the ways in which a word processor can disrupt common writing practices, we must gain a better understanding of how a text is actually composed in real time, with or without a computer. Although the various writing processes have been clearly identified, the functional scenario describing the succession of writing phases and accompagnying activities is still poorly defined. The marks produced by writers on paper, whether linguistic (words, sentence fragments, sentences) or non-linguistic (arrows, underlining, indexation, diagrams, etc.), reflect the planning, translating, and revising processes being carried out by the writer. Sharples and Pemberton (1990) describe the exact functions of these marks in the elaboration of the ideas to be translated into text form (levels of organization). However, more knowledge about their frequency of use at the different stages of text composition is required. This is one of the goals of the present experimental observation. For the most part, such marks cannot be displayed and manipulated on the screen of a standard word processor as they can on paper. It is therefore crucial that we observe the means employed by writers to adapt their use of these necessary devices to word processing. The main results indicate that writers who use a word processor still resort to "pencil and paper" for the initial planning. The small amount of text preparation done by computer users (manifested by chronological and hierarchical organization marks) compared to writers who produce without a word processor is compensated by extensive revision on the screen. However, while writing strategies are highly dependent on production conditions, the quality of the texts produced does not vary significantly. The possibility of eliminating one of the important drawbacks of computer-assisted writing i. e. the fact that the information must be displayed linearly on the screen, is currently being studied by designers of planning aids that accompagny word processors. Before such aids can actually be developed, however, more knowledge is needed of the phases of writing and the marks used by writers throughout the production process

Analysis of the fraction of clear sky at the La Palma and Mt Graham sites

The fraction of available telescope time is one of the most important requirements for selecting astronomical sites affecting the performance of ground based telescopes. A quantitative survey of clouds coverage at La Palma and Mt.Graham is presented using both ground and satellite based data. The aim of this work is deriving clear nights for the satellite infrared channels and verifying the results using ground based observations. At La Palma we found a mean percentage of clear nights of 62.6% from ground and 71.9% from satellite. Taking into account the fraction of common nights we found a concordance of 80.7% clear nights from ground and satellite. At Mt.Graham we found a 97% of agreement between Columbine heliograph and night time observing log. From Columbine heliograph and TOMS-OMI satellite we found about 45% of clear nights, while satellite data (GOES, TOMS) are much more dispersed than those ones of La Palma. Setting a statistical threshold we retried a comparable seasonal trend between heliograph and satellite.Comment: 14 pages, 18 figures, 6 tables, MNRAS accepted on September 23 200

Fraction of clear skies above astronomical sites: a new analysis from the GOES12 satellite

Comparing the number of clear nights (cloud free) available for astronomical observations is a critical task because it should be based on homogeneous methodologies. Current data are mainly based on different judgements based on observer logbooks or on different instruments. In this paper we present a new homogeneous methodology on very different astronomical sites for modern optical astronomy, in order to quantify the available night time fraction. The data are extracted from night time GOES12 satellite infrared images and compared with ground based conditions when available. In this analysis we introduce a wider average matrix and 3-Bands correlation in order to reduce the noise and to distinguish between clear and stable nights. Temporal data are used for the classification. In the time interval 2007-2008 we found that the percentage of the satellite clear nights is 88% at Paranal, 76% at La Silla, 72.5% at La Palma, 59% at Mt. Graham and 86.5% at Tolonchar. The correlation analysis of the three GOES12 infrared bands B3, B4 and B6 indicates that the fraction of the stable nights is lower by 2% to 20% depending on the site

The Early Palomar Program (1950-1955) for the Discovery of Classical Novae in M81: Analysis of the Spatial Distribution, Magnitude Distribution, and Distance Suggestion

Data obtained in the 1950-1955 Palomar campaign for the discovery of classical novae in M81 are set out in detail. Positions and apparent B magnitudes are listed for the 23 novae that were found. There is modest evidence that the spatial distribution of the novae does not track the B brightness distribution of either the total light or the light beyond an isophotal radius that is 70\arcsec from the center of M81. The nova distribution is more extended than the aforementioned light, with a significant fraction of the sample appearing in the outer disk/spiral arm region. We suggest that many (perhaps a majority) of the M81 novae that are observed at any given epoch (compared with say $10^{10}$ years ago) are daughters of Population I interacting binaries. The conclusion that the present day novae are drawn from two population groups, one from low mass white dwarf secondaries of close binaries identified with the bulge/thick disk population, and the other from massive white dwarf secondaries identified with the outer thin disk/spiral arm population, is discussed. We conclude that the M81 data are consistent with the two population division as argued previously from (1) the observational studies on other grounds by Della Valle et al. (1992, 1994), Della Valle & Livio (1998), and Shafter et al. (1996) of nearby galaxies, (2) the Hatano et al. (1997a,b) Monte Carlo simulations of novae in M31 and in the Galaxy, and (3) the Yungelson et al. (1997) population synthesis modeling of nova binaries. Two different methods of using M81 novae as distance indicators give a nova distance modulus for M81 as $(m-M)_0 = 27.75$, consistent with the Cepheid modulus that is the same value.Comment: 24 pages, 7 figures, accepted to PAS

A possible explanation for the discrepancy between ELISA and neutralising antibodies to tetanus toxin

The structure and protective activity of tetanus antibodies elicited in rabbits after whole-cell pertussis diphtheria-tetanus vaccine (DTPw) vaccination was studied. ELISA antibody levels and toxin neutralisation activity (TNT) were measured in individual serum samples. The ratio of symmetric and asymmetric (functionally monovalent) IgG molecules was determined by concanavalin A (Con A) chromatography. This test is based on the fact that the carbohydrate group responsible for the molecular asymmetry has high affinity for the lectin Con A. Asymmetric molecule ratio was observed to increase with immunisation time, as well as differences between TNT and ELISA levels. All serum samples were overestimated by ELISA as compared to TNT assay, in line with the markedly higher proportion of asymmetric molecules which have lower toxin neutralising activity. Protective levels could not be predicted reasonably from ELISA results below 0.222 IU/ml, because this methodology fails to discriminate between both types of antibodies and only an in vivo serum neutralisation procedure (TNT) reflects the true neutralising serum activity. Copyright (C) 2000 Elsevier Science Ltd.Fil: Dokmetjian, Jose Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Della Valle, C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Lavigne, V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: De Luján, Calcagno M.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Físico Matemática; ArgentinaFil: Manghi, Marcela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; Argentin

The H-alpha Light Curves and Spatial Distribution of Novae in M81

We present the results of a preliminary H-alpha survey of M81 for novae conducted over a 5 month interval using the 5' field of view camera (WFCAM) on the Calypso Telescope at Kitt Peak, AZ. We observed M81 nearly every clear night during this interval, covering the entire galaxy, and discovered 12 novae. Our comprehensive time coverage allowed us to produce the most complete set of H-alpha light curves for novae in M81 to date. A raw nova rate for M81 gives 23 yr^-1 which, because of the nature of our survey, is a hard lower limit. An analysis of the completeness in our survey gives a corrected nova rate of 30 yr^-1. This agrees well with the rate of 33 (+13,-8) yr^-1, derived from Monte Carlo simulations using nova light curves and survey frame limits. The spatial distribution of the novae we discovered follows the bulge light much better than the disk or total light according to Kolmogorov - Smirnov tests of their radial distributions. The asymmetry in the distribution of novae across the major axis line of M81 implies a bulge-to-disk nova ratio of > 9 and supports the idea that novae originate primarily in older stellar populations.Comment: 41 pages, 10 figures, and 7 tables, accepted, to appear in AJ, Feb 2004, updated raw and completeness corrected nova rate

Quasi Harmonic Lattice Dynamics and Molecular Dynamics calculations for the Lennard-Jones solids

We present Molecular Dynamics (MD), Quasi Harmonic Lattice Dynamics (QHLD) and Energy Minimization (EM) calculations for the crystal structure of Ne, Ar, Kr and Xe as a function of pressure and temperature. New Lennard-Jones (LJ) parameters are obtained for Ne, Kr and Xe to reproduce the experimental pressure dependence of the density. We employ a simple method which combines results of QHLD and MD calculations to achieve densities in good agreement with experiment from 0 K to melting. Melting is discussed in connection with intrinsic instability of the solid as given by the QHLD approximation. (See http://www.fci.unibo.it/~valle for related papers)Comment: 7 pages, 5 figures, REVte

Switching management in couplers with biharmonic longitudinal modulation of refractive index

We address light propagation in couplers with longitudinal biharmonic modulation of refractive index in neighboring channels. While simplest single-frequency out-of-phase modulation allows suppression of coupling for strictly defined set of resonant frequencies, the addition of modulation on multiple frequency dramatically modifies the structure of resonances. Thus, additional modulation on double frequency may suppress primary resonance, while modulation on triple frequency causes fusion of primary and secondary resonances.Comment: 13 pages, 4 figures, to appear in Optics Letter