Search results for "ALK"
showing 10 items of 4314 documents
Atomic Transitions and Population Control by Laser Frequency Scanning Speed and Magnetic Field
2022
In this thesis the influence of laser radiation and external uniform magnetic field on alkali-metal atomic vapor is studied. We focused on three topics. In the first part, we examined atomic population control in an M-type system to demonstrate that such systems can serve as universal three-bit logical devices. The second part concerns an experiment of atomic spectroscopy. From the fluorescence spectra recorded for stationary, transient and non-stationary interaction regimes, we were able to extract important parameter values which are the relaxation rate of the lower energy levels to the equilibrium isotropic state, the diffusion coefficient in a buffered vapor cell, and the corresponding …
Formation of narrow optical resonances in thin atomic vapor layers of Cs, Rb, K and applications.
2019
This thesis presents the study of coherent light interaction with a sub-wavelength atomic alkali vapor layer confined in a nano-cell and applications for the formation of narrow optical resonances.We develop a theoretical model describing the resonant interaction of the laser light with the thin alkali vapor layer in the presence of an external static magnetic field. We show that due to a transient regime of interaction, only slow atoms contribute to the signal and their transmission spectrum is essentially Doppler-free. The nature of the obtained spectra makes the transmission spectroscopy from a nano-cell a convenient technique to perform studies of closely-spaced atomic transitions and i…
Selective reflection spectroscopy of alkali vapors confined in nanocells and emerging sensing applications
2019
This thesis is aimed at studying the resonant interaction of a laser radiation with an atomic alkali vapor layer of wavelength-scale thickness confined in an optical nanocell; and emerging sensing applications.We focus our attention on the selective reflection arising at the interface between a dielectric window and a resonant alkali vapor, and show that the derivative of selective reflection spectra exhibit narrow resonances whose maxima are located exactly at atomic resonance frequencies. These resonances are observed with a spectral linewidth up to fifteen times smaller than the Doppler linewidth of the medium and their amplitudes scale linearly with respect to the transitions ones. Owin…
Le désherbage d’automne contre l’ergot du seigle les traitements herbicides d’automne, un levier chimique efficace de lutte contre l’ergot du seigle
2013
Context and study: Trials in field allowed to show a link between a good grass weeding (blackgrass and rye grass) and extent of ergot contaminations. Makhteshim Agan France and Arvalis tested on 15 trials in 2011-2012, 2 ureas, as isoproturon against blackgrass, alone or in pro-gram with a sulfonylurea, to evaluate their indirect effect against ergot. Field trials were set up on sensitive crops to ergot (rye, wheat and triticale) infested with artificial ergot contaminations and weed seeds sensible to ALS. Contaminations were evaluated first in field on weeds and on crop, and then on harvest, by assessing sclerotia and alkaloids content in harvested samples. results: For all evaluation mean…
The Urban Exposome during Pregnancy and Its Socioeconomic Determinants
2018
Background: The urban exposome is the set of environmental factors that are experienced in the outdoor urban environment and that may influence child development. Objective: The authors’ goal was to describe the urban exposome among European pregnant women and understand its socioeconomic determinants. Methods: Using geographic information systems, remote sensing and spatio-temporal modeling we estimated exposure during pregnancy to 28 environmental indicators in almost 30,000 women from six population-based birth cohorts, in nine urban areas from across Europe. Exposures included meteorological factors, air pollutants, traffic noise, traffic indicators, natural space, the built environment…
Identification of bound alcohols in soil humic acids by gas chromatography-mass spectrometry
2000
International audience; Humic acids are complex, partly macromolecular, yellow-brownish substances occurring in soils, waters and sediments. In order to shed some light on their molecular structure, crop humic acids were cleaved by alkaline hydrolysis (KOH). The products were fractionated by thin layer chromatography to give mono-alcohols which were analysed as acetate derivatives by gas chromatography coupled to mass spectrometry. Linear alcohols, sterols, stanols and plant-derived triterpenoid alcohols were identified by co-injection of pure standards and by comparison with literature data. These findings imply that alcohols could have been incorporated into the humic matrix by esterifica…
L'historique du tunnel sous la manche : une brève revue des contributions les plus marquantes
2014
The Channel Tunnel is the largest underground geotechnical project undertaken in Europe during the 20th century. There have been numerous proposals since the early 19th century, especially by Thomé de Gamond (1867), Potier and de Lapparent (1877), and Destombes and Shephard-Thorn (1971). This paper discusses the history of the most important geological investigations for the Channel Tunnel bored in the Lower Cenomanian Chalk Marl.
The Crosstalk of Adipose-Derived Stem Cells (ADSC), Oxidative Stress, and Inflammation in Protective and Adaptive Responses
2020
International audience; The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs is a major goal in repair medicine. Stem cells are classified by their potential to differentiate into functional cells. Compared with other sources, adipose-derived stem cells (ADSCs) have the advantage of being abundant and easy to obtain. ADSCs are considered to be tools for replacing, repairing, and regenerating dead or damaged cells. The capacity of ADSCs to maintain their properties depends on the balance of complex signals in their microenvironment. Their properties and the associated outcomes are in part regulated by reactive oxygen species, which medi…
Do Women and Men over 70 Years Old Similarly Benefit from a One-Year Training Program?
2010
Background and Aims : Exercise capacity declines with age and is improved with exercise training. The aim of this study was to characterize the effects of a one-year combined exercise training in subjects over 70 years old, and to examine the eventual differences obtained between men and women. Methods : After baseline evaluation, 24 subjects (12 men and 12 women) over 70 years old underwent moderate intensity training with aerobic and resistance exercises, 3 hours a week over one year. Workload, oxygen uptake (VO2) and heart rate were measured during a symptom-limited exercise test. The distance walked in 6 minutes (6-MWT) was also registered, and the maximal strength was measured on knee …
Walk tests : a standardizable tool to assess capacities in cardio-vascular disease
2011
Cardiovascular and cerebrovascular diseases remain the first cause of mortality and handicap in the world. With the improvements in the management of the acute phase, the number of patients with limited exercise capacity due to chronic cardiovascular disease is increasing. The aim of this thesis was to conduct a thorough study of the use of standardized walk tests to assess exercise capacity in coronary artery disease patients. We first explain the concepts of handicap and quality of life in chronic diseases, and the need for functional evaluations in order to assess their impact and evolution. We then present the current modalities of cardiac rehabilitation, emphasizing the importance of p…