Simulation du cycle de l'azote à travers l'écosystème pélagique de la baie sud de la mer du Nord

The present work aims at establishing a mathematical model which describes the seasonal evolution of the most characteristic constituents of the pelagic phase of the ecosystem in the southern bight of the North Sea. After the notions of system and model, as applied to the analysis of the marine environment, have been defined, the different analytical forms that are required to describe the various ecological interactions are explained and the principal ecological models which were published in the litterature are reviewed. They are divided into five distinct categories. The experimental data which have enabled the establishment of the mean yearly cycles of nitrogen through the different compartments of this particular ecosystem are then examined. These yearly cycles are considered to be a necessary preliminary for any modeling attempt. The equations for the seasonal evolution of dissolved nitrogen, phytoplankton, zooplankton and dissolved organic matter in the Belgian coastal zone, supposed to be spatially homogenous, i.e. one box, are then established. The results of this model are in good agreement with the data collected in situ. Furthermore, to reveal the spatial variations of these variables in the eastern part of the southern bight of the North Sea this model has been extended to this entire marine area, which for this purpose has been divided into thirty boxes, the geographical delimitation of which is based on the distribution of the residual currents. Finally, the great number of parameters which need to be introduced in the evolution equations and whose values are not known very precisely, is identified as a major handicap for ecological modeling. This is why a sensitivity analysis of the parameters is made, to emphasize the ones which influence the dynamics of this ecosystem the most, on a yearly average

Accelerated convergence method for fast Fourier transform simulation of coupled cavities

Fast Fourier transform (FFT) simulation was used to calculate the power and spatial distribution of resonant fields in optical cavities. This is an important tool when characterizing the effect of imperfect geometry and mirror aberrations. This method is, however, intrinsically slow when the cavities are of relatively high finesse. When this is the case, an accelerated convergence scheme may be used to calculate the steady-state cavity field with a speed that is orders of magnitude faster. The rate of convergence of this method, however, is unpredictable, as many different factors may detrimentally affect its performance. In addition, its use in multiple cavity configurations is not well understood. An in-depth study of the limitations and optimization of this method is presented, together with a formulation of its use in multiple cavity configurations. This work has not only resulted in consistent improvement in performance and stability of the accelerated convergence method but also allows the simulation of optical configurations, which would not previously have been possible

Molecular evidence for the natural production of homozygous Cupressus sempervirens L. lines by Cupressus dupreziana seed trees

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A Brief Report: Preliminary Findings for Pathways to Resilience among Critical Incident Stress Management Responders

Previous research by Burnett, Pichot, and Bailey (2019) found support for several innate well-being and behavioral action variables that contribute to Everly’s Psychological Body Armor’s (PBA) two unique interacting human protective pathways (proactive and reactive resilience) among a non-disaster mental health response population. However, research is limited regarding the unique proactive and reactive pathway variables that contribute to resilience capacity among trained disaster mental health responders. Participants (N = 63) were novice and experienced disaster mental health responders who attended a Critical Incident Stress Management (CISM) training conference in Michigan that completed the same 14 measures used in the original Burnett, Pichot, and Bailey study. Similar to the Burnett, Pichot, and Bailey study, hierarchical regression analyses revealed that for the proactive pathway, self-acceptance and subjective happiness were significant unique predictors for resilience capacity, while psychological distress and perceived stress were significant unique predictors for the reactive pathway. A qualitative comparative analysis (QCA) found that all but one of the cases met the observation criteria for having high resilience. However, when the dataset for this study was combined with the original study (NCombined = 265), QCA revealed that overall; having professional CISM training contributed more to strong resilience making the proactive pathway irrelevant

Empowering Frontline Trauma Responders: Keys to Resilience

CISM teams and responders play a vital role in helping those who have been affected by traumatic to successfully manage their stress reactions. It is important that individual CISM responders, along with teams, take time to incorporate an active resilience-based approach which makes use of well-being traits

Ultra-Wideband Microwave Imaging of Heterogeneities

International audienceThe technique of time-reversal acoustics was applied to image a bottle filled with saline, using an eight element Vivaldi antenna array with frequency bandwidth 2 to 8 GHz. At these short length scales, a smooth three-dimensional image of the bottle was obtained, with the usual limitations imposed by limited offset and frequency. Time snapshots of the wavefield evolution in reversed time are presented for two real data sets. The first, shows the focusing for the single target of the bottle, while the second demonstrates the principle for two targets