Numerical implementation of low-PMD spun fibres with precomputed M(w) matrices

Poster With the use of the coarse-step method for simulating the phenomenon of PMD the fibre-twist as not included into the equations. This was an obstacle in representing low-PMD spun fibres numerially.

Aller et venir:des verbes de déplacement aux auxiliaires aspectuels-temporels-modaux

Après avoir décrit le fonctionnement des verbes aller et venir, nous développons l’hypothèse selon laquelle leur grammaticalisation en auxiliaires s’effectue sur la base de l’élément spatial qui structure tant leur sémantisme commun – le déplacement vers une destination – que leur différence : l’orientation déictique (venir) / non déictique (aller) du déplacement. Nous testons cette hypothèse en analysant les principaux emplois des périphrases de structure [aller / venir (+prép.) + V(infinitif, gérondif)]. After a description of how movement verbs aller and venir work, we develop an hypothesis according to which their grammaticalisation into auxiliaries relies on the spatial element that structures their shared semantics – movement towards a destination - as well as their distinctive feature : a deictic (venir) or non deictic (aller) orientation of the movement. We test that hypothesis against an analysis of the main uses of periphrases in the [aller / venir (+ prep.) + V(infinitive, present participle)] pattern.

The effects of required/sequenced preparatory courses on academic success and retention at a community college

This dissertation had two purposes: first, to analyze how required sequenced college preparatory courses in mathematics, reading, and writing affect students' academic success and, second, to add to a theoretical model for predicting student retention at a community college. Grade point average, number of degree credits earned, and re-enrollment rate were measured as determinants of academic success. The treatment group had a significantly higher grade point average than the control group. There was no significant difference in the number of degree credits earned or re-enrollment rate for the groups. A series of logistic regressions used the independent variables E-ASSET scores in math, reading, and writing; number of college prep areas required; credits earned; grade point average; students' status; academic restrictions/required course sequencing; sex; race; and socio-economic status to determine the predictor variables for retention. The academic variable that showed the greatest potential as a predictor for retention was grade point average. Overall, receiving financial aid was the greatest predictor for re-enrollment. For a financial aid recipient the odds of re-enrollment were 2.70 times more likely than if no financial aid was received.

The effects of required/sequenced preparatory courses on academic success and retention at a community college

This dissertation had two purposes: first, to analyze how required sequenced college preparatory courses in mathematics, reading, and writing affect students' academic success and, second, to add to a theoretical model for predicting student retention at a community college. Grade point average, number of degree credits earned, and reenrollment rate were measured as determinants of academic success. The treatment group had a significantly higher grade point average than the control group. There was no significant difference in the number of degree credits earned or re-enrollment rate for the groups. A series of logistic regressions used the independent variables E-ASSET scores in math, reading, and writing; number of college prep areas required; credits earned; grade point average; students' status; academic restrictions/required course sequencing; sex; race; and socio-economic status to determine the predictor variables for retention. The academic variable that showed the greatest potential as a predictor for retention was grade point average. Overall, receiving financial aid was the greatest predictor for reenrollment. For a financial aid recipient the odds of reenrollment were 2.70 times more likely than if no financial aid was received.

Radionuclides measured on 27 water bottle profiles during POLARSTERN cruise ANT-XXIV/3

As part of the GEOTRACES Polarstern expedition ANT XXIV/3 (ZERO and DRAKE) we have measured the vertical distribution of 234Th on sections through the Antarctic Circumpolar Current along the zero meridian and in Drake Passage and on an EW section through the Weddell Sea. Steady state export fluxes of 234Th from the upper 100m, derived from the depletion of 234Th with respect to its parent 238U, ranged from 621±105 dpm/m**2/d to 1773±90 dpm/m**2/d. This 234Th flux was converted into an export flux of organic carbon ranging from 3.1-13.2 mmolC/m**2/d (2.1-9.0 mmolC/m**2/d) using POC/234Th ratio of bulk (respectively >50 µm) suspended particles at the export depth (100 m). Non-steady state fluxes assuming zero flux under ice cover were up to 23% higher. In addition, particulate and dissolved 234Th were measured underway in high resolution in the surface water with a semi-automated procedure. Particulate 234Th in surface waters is inversely correlated with light transmission and pCO2 and positively with fluorescence and optical backscatter and is interpreted as a proxy for algal biomass. High resolution underway mapping of particulate and dissolved 234Th in surface water shows clearly where trace elements are absorbed by plankton and where they are exported to depth. Quantitative determination of the export flux requires the full 234Th profile since surface depletion and export flux become decoupled through changes in wind mixed layer depth and in contribution to export from subsurface layers. In a zone of very low algal abundance (54-58 °S at the zero meridian), confirmed by satellite Chl-a data, the lowest carbon export of the ACC was observed, allowing Fe and Mn to maintain their highest surface concentrations (Klunder et al., this issue, Middag et al., this issue). An ice-edge bloom that had developed in Dec/Jan in the zone 60-65 °S as studied during the previous leg (Strass et al., in prep) had caused a high export flux at 64.5 °S when we visited the area two months later (Feb/March). The ice-edge bloom had then shifted south to 65-69 °S evident from uptake of CO2 and dissolved Fe, Mn and 234Th, without causing export yet. In this way, the parallel analysis of 234Th can help to explain the scavenging behaviour of other trace elements.

Comparison of nitrogen isotopic values from different preparation methods

We are writing to comment on the work of Tamburini et al. (2003, doi:10.1029/2000PA000616). During the course of subsequent discussions between the authors and ourselves, it has become clear that the published sedimentary nitrogen isotopic values for Ocean Drilling Program (ODP) Site 724 are in error. Our reanalysis of sediment samples from the same intervals has revealed a significant offset from the original d15N data, requiring a revised assessment of their initial interpretation. The purposes of this comment are to (1) address the origin of these errors; (2) outline a protocol for future validation of nitrogen isotopic analyses; and (3) provide revised interpretations of the sedimentary d15N data in terms of the regional relative contributions of denitrification and nitrogen fixation and mean state of the southwest monsoon. (2) Nitrogen isotopic values measured on late Quaternary sediments at Arabian Sea ODP Site 724 by Tamburini et al. (2003, doi:10.1029/2000PA000616) are inexplicably different from a number of published records of d15N from very nearby on the Oman margin (Altabet et al., 1995, doi:10.1038/373506a0; 1999, doi:10.1029/1999PA900035; 2002, doi:10.1038/415159a; Higginson et al., 2004, doi:10.1016/j.gca.2004.03.015) and elsewhere in the Arabian Sea (Reichart et al., 1998, doi:10.1029/98PA02203). These data were generated using similar instrumentation (elemental analyzer coupled with an isotope ratio mass spectrometer) and analytical methodology to those already published. Concerned by this clear discrepancy, we analyzed aliquots of sediment from the same depth intervals for nitrogen abundance and bulk sedimentary nitrogen isotopes. We have been unable to duplicate the values published by Tamburini et al. (2003, doi:10.1029/2000PA000616 ), even after analysis of multiple replicates and due consideration of natural sediment heterogeneities and postrecovery sample storage.

Middle atmopsheric cabon monoxide above Kiruna, Sweden, 2008-2015

This data set contains profiles of atmospheric carbon monoxide (CO) concentrations retrieved from measurements made by the Kiruna Microwave Radiometer (KIMRA), housed at the Swedish Institute for Space Physics, Kiruna. The data is retrieved on a standard pressure grid that is 62 layers, spaced approximately equally in altitude between 2 km and 124 km. The current time range of the data is December 2008 to May 2015, with data gaps corresponding to Summer periods when the CO concentrations in the middle atmosphere drop to very low values, or to non-operation of the instrument. The profile information is considered useful between approximately 48 km and 86 km, specifically where the measurement response is above 0.8. If the CO profiles are being compared to another data set with significantly higher altitude resolution, the averaging kernel matrix should be used to smooth the higher resolution data. The error in the profile from statistical noise on the measured spectrum is also provided. This work has been funded by the German Federal Ministry of Education and Research through the research project: Role Of the Middle atmosphere in Climate (ROMIC, https://romic.iap-kborn.de).

Coccosphere geometry measurements from culture experiments on the coccolithophore species Calcidiscus leptoporus, Calcidiscus quadriperforatus and Helicosphaera carteri

Coccolithophores are a key phytoplankton group that exhibit remarkable diversity in their biology, ecology, and calcitic exoskeletons (coccospheres). An understanding of the physiological processes that underpin coccosphere architecture is essential for maximizing the information that can be retrieved from their extensive fossil record. Using culturing experiments on four modern species from three long-lived families, we investigate how coccosphere architecture responds to population shifts from rapid (exponential) to slowed (stationary) growth phases as nutrients become depleted. These experiments reveal statistical differences in cell size and the number of coccoliths per cell between these two growth phases, specifically that cells in exponential-phase growth are typically smaller with fewer coccoliths, whereas cells experiencing growth-limiting nutrient depletion have larger coccosphere sizes and greater numbers of coccoliths per cell. Although the exact numbers are species-specific, these growth-phase shifts in coccosphere geometry are common to four different coccolithophore families (Calcidiscaceae, Coccolithaceae, Isochrysidaceae, Helicosphaeraceae), demonstrating that this is a core physiological response to nutrient depletion across a representative diversity of this phytoplankton group. Polarised light microscopy was used for all coccosphere geometry measurements.

Tempo para aprender vs tempo para brincar

Relatório de Estágio apresentado à Escola Superior de Educação de Paula Frassinetti para a obtenção de grau de Mestre em Educação Pré-Escolar e Ensino do 1º Ciclo do Ensino Básico