Impact of Extremely Low-Frequency Magnetic and Electric Stimuli on Vestibular-Driven Outcomes

The vestibular system is extremely sensitive to electric fields (E-fields). Indeed, vestibular hair cells are graded potential cells and this property makes them very susceptible to small membrane potential modulations. Studies show that extremely low-frequency magnetic fields (ELF-MF) induced E-fields impact postural control in which the vestibular system plays an important role. However, the knowledge of whether this is indeed a vestibular specific effect is still pending. Considering its crucial role and the specific neurophysiological characteristics of its hair cells, the vestibular system emerges as an ELF-MF likely target The three studies presented in this thesis aimed to further address whether ELF-MF modulate vestibular-driven outcomes. Studies 1 and 2 aimed to investigate postural responses while more specifically targeting the vestibular system. However, we did not find any modulation in either study. Nonetheless, based on both studies, study 3 aimed to determine whether the orientation and frequency of our stimulations were more likely to target the otoliths. Therefore, the third study looked at the subjective visual vertical. Here, we found a potential ELF-MF utricular modulation. This thesis is the first steppingstone in a new field of research. Further investigations regarding the interaction between the ELF-MF and the vestibular system will have to look at more reflexives vestibular outcomes. Nonetheless, this thesis provides valuable information that will need to be taken into consideration when writing future international guidelines and standards related to ELF-MF

Distance and patch richness affect the use of exploitation versus interference competition in central place foraging eastern chipmunks, Tamias striatus

Experiments showed that the richer the (experimental) food patch, the more likely were chipmunks to tolerate one another

Le rôle des riverains dans le façonnement des interfaces ville-forêt

L’objet de cet article est d’analyser les modes d’habiter des populations résidentes dans les lotissements périurbains au contact de la forêt des Landes de Gascogne. Il s’agit, à partir d’un travail d’enquête, de comprendre le fonctionnement de ces franges urbaines : les représentations paysagères et les pratiques récréatives que les riverains ont de la forêt ainsi que les conséquences de cette proximité dans le façonnement des paysages d’interface. Alors même que la forêt n’est pas toujours un facteur prépondérant dans les choix résidentiels initiaux, le discours des habitants relève de valeurs esthétiques émotionnelles qui témoignent de la force de certains usages et fonctions attribués à la forêt, si artificielle soit-elle. Ces valeurs s’expriment via l’appréciation de certaines composantes du paysage forestier et à travers l’aménagement du cadre de vie dans des interfaces dont le façonnement relève plus d’initiatives individuelles que de projets collectifs.The aim of this article is to analyse the ways in which resident populations inhabit suburban plots of land on the fringes of the forest of the Landes de Gascogne. The results of a survey are used to understand the way these urban fringes function : the representations of local inhabitants of the forest landscape and the recreational activities they practise in the forest as well as the consequences of this proximity on the way these landscape interfaces are shaped. Whereas the forest is not always among prevalent factors in initial residential choices, the discourse of the inhabitants relates to emotional aesthetic values which bear witness to the importance of certain uses and functions attributed to the forest, however artificial this landscape may be. These values are expressed via the appreciation of certain components of the forest landscape and through the development of the living environment in interfaces the shaping of which is more often the result of individual initiatives than that of community projects

Anaesthesiology in Ruminants: paradoxical effects of législations

European Community laws on livestock allow the use of several sedative substances for which maximum residue limits have been defined. The withdrawal periods for these drugs vary from one country to another. Finally, they do not take into account the individual physiology of young animals. The author recommends using recent substances safely, as they reduce the risk to consumers.Chez les animaux de rente, les législations communautaires autorisent l'usage de quelques substances sédatives pour lesquelles des limites maximales de résidus ont été établies. Elles imposent des délais d'attente qui varient d'un pays à un autre. Enfin elles ne tiennent pas compte de la physiologie individuelle des jeunes animaux. L'auteur préconise l'utilisation de substances récentes en toute sécurité. Leur emploi diminue les risques pour le consommateur

Is activation of the vestibular system by electromagnetic induction a possibility in an MRI context?

In recent years, an increasing number of studies have discussed the mechanisms of vestibular activation in strong magnetic field settings such as occur in a magnetic resonance imaging scanner environment. Amid the different hypotheses, the Lorentz force explanation currently stands out as the most plausible mechanism, as evidenced by activation of the vestibulo‐ocular reflex. Other hypotheses have largely been discarded. Nonetheless, both human data and computational modeling suggest that electromagnetic induction could be a valid mechanism which may coexist alongside the Lorentz force. To further investigate the induction hypothesis, we provide, herein, a first of its kind dosimetric analysis to estimate the induced electric fields at the vestibular system and compare them with what galvanic vestibular stimulation would generate. We found that electric fields strengths from induction match galvanic vestibular stimulation strengths generating vestibular responses. This review examines the evidence in support of electromagnetic induction of vestibular responses, and whether movement‐induced time‐varying magnetic fields should be further considered and investigated

Influence of the consumption pattern of magnesium from magnesium-rich mineral water on magnesium bioavailability

It is generally considered that the absorption of Mg is inversely related to the ingested dose. The objective of the present study was to determine if the mode of administration (bolus v. consumption throughout the day) could influence Mg bioavailability from Mg-rich natural mineral water comparing the same nutritional Mg amount (126mg). Using a 2d cross-over design, twelve healthy men were asked to drink 1·5 litres Mg-rich mineral water either as 2×750ml or 7×212ml throughout the day. Two stable isotopes (25Mg and 26Mg) were used to label the water in order to distinguish both regimens. Fractional apparent Mg absorption was determined by faecal monitoring and Mg retention was determined by measuring urinary excretion of Mg isotopes. Higher Mg absorption (50·7 (sd 12·7) v. 32·4 (sd 8·1) %; P=0·0007) and retention (47·5 (sd 12·9) v. 29·0 (sd 7·5) %; P=0·0008) from Mg-rich mineral water were observed when it was consumed in seven servings compared with larger servings. Thus, regular water consumption throughout the day is an effective way to increase Mg bioavailability from Mg-rich mineral wate