Influence of phyllosilicate mineral assemblages, fabrics, and fluids on the behavior of the Punchbowl fault, southern California

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95206/1/jgrb13457.pd

Biophysical Basis for Three Distinct Dynamical Mechanisms of Action Potential Initiation

Transduction of graded synaptic input into trains of all-or-none action potentials (spikes) is a crucial step in neural coding. Hodgkin identified three classes of neurons with qualitatively different analog-to-digital transduction properties. Despite widespread use of this classification scheme, a generalizable explanation of its biophysical basis has not been described. We recorded from spinal sensory neurons representing each class and reproduced their transduction properties in a minimal model. With phase plane and bifurcation analysis, each class of excitability was shown to derive from distinct spike initiating dynamics. Excitability could be converted between all three classes by varying single parameters; moreover, several parameters, when varied one at a time, had functionally equivalent effects on excitability. From this, we conclude that the spike-initiating dynamics associated with each of Hodgkin's classes represent different outcomes in a nonlinear competition between oppositely directed, kinetically mismatched currents. Class 1 excitability occurs through a saddle node on invariant circle bifurcation when net current at perithreshold potentials is inward (depolarizing) at steady state. Class 2 excitability occurs through a Hopf bifurcation when, despite net current being outward (hyperpolarizing) at steady state, spike initiation occurs because inward current activates faster than outward current. Class 3 excitability occurs through a quasi-separatrix crossing when fast-activating inward current overpowers slow-activating outward current during a stimulus transient, although slow-activating outward current dominates during constant stimulation. Experiments confirmed that different classes of spinal lamina I neurons express the subthreshold currents predicted by our simulations and, further, that those currents are necessary for the excitability in each cell class. Thus, our results demonstrate that all three classes of excitability arise from a continuum in the direction and magnitude of subthreshold currents. Through detailed analysis of the spike-initiating process, we have explained a fundamental link between biophysical properties and qualitative differences in how neurons encode sensory input

Perception of Thermal Pain and the Thermal Grill Illusion Is Associated with Polymorphisms in the Serotonin Transporter Gene

AIM: The main aim of this study was to assess if the perception of thermal pain thresholds is associated with genetically inferred levels of expression of the 5-HT transporter (5-HTT). Additionally, the perception of the so-called thermal grill illusion (TGI) was assessed. Forty-four healthy individuals (27 females, 17 males) were selected a-priori based on their 5-HTTLPR/rs25531 ('tri-allelic 5-HTTLPR') genotype, with inferred high or low 5-HTT expression. Thresholds for heat- and cold-pain were determined along with the sensory and affective dimensions of the TGI. RESULTS: Thresholds to heat- and cold-pain correlated strongly (rho  = -0.58, p<0.001). Individuals in the low 5-HTT-expressing group were significantly less sensitive to heat-pain (p = 0.02) and cold-pain (p = 0.03), compared to the high-expressing group. A significant gender-by-genotype interaction also emerged for cold-pain perception (p = 0.02); low 5-HTT-expressing females were less sensitive. The TGI was rated as significantly more unpleasant (affective-motivational dimension) than painful (sensory-discriminatory dimension), (p<0.001). Females in the low 5-HTT expressing group rated the TGI as significantly less unpleasant than high 5-HTT expressing females (p<0.05), with no such differences among men. CONCLUSION/SIGNIFICANCE: We demonstrate an association between inferred low 5-HTT expression and elevated thresholds to thermal pain in healthy non-depressed individuals. Despite the fact that reduced 5-HTT expression is a risk factor for chronic pain we found it to be related to hypoalgesia for threshold thermal pain. Low 5-HTT expression is, however, also a risk factor for depression where thermal insensitivity is often seen. Our results may thus contribute to a better understanding of the molecular underpinnings of such paradoxical hypoalgesia. The results point to a differential regulation of thermoafferent-information along the neuraxis on the basis of 5-HTT expression and gender. The TGI, suggested to rely on the central integration of thermoafferent-information, may prove a valuable tool in probing the affective-motivational dimension of these putative mechanisms

Local urban sprawl accuracy from image segmentation uncertainties simulation

Accuracy 2014, East Lansing, USA, 08-/07/2014 - 11/07/2014International audienceUrban sprawl can be monitored using remote sensing. One method is to segment and classify the images to obtain polygons of impervious areas and then derive urban patches. We evaluated the geometric accuracy of the impervious polygons using the boundary distance distribution signature (BDDS) and investigated their propagation to spatial indicators of urban sprawl indicators at municipality scale, south of France, from impervious polygons uncertainties simulation.L'étalement urbain peut être surveillé par télédétection. Une méthode consiste à segmenter et classer les images pour obtenir des polygones de zones imperméables et ensuite dériver des zones urbaines. Nous avons évalué la précision géométrique des polygones imperméables à l 'aide de la signature de distribution de distance limite (BDDS) et avons étudié leur propagation aux indicateurs spatiaux des indicateurs d' étalement urbain à l 'échelle de la municipalité, au sud de la France

Propagating Geometric Uncertainties from Image Segmentation to Spatial Indicators of Urban Sprawl

International audienceUrban sprawl is a crucial issue for governments at all administrative levels. Monitoring urban sprawl requires spatial indicators at varying spatial scales. These indicators integrate information about impervious areas, population census, socioeconomic context, agricultural activities and soil quality. All the input data, however, suffer from uncertainties which affect the accuracy of the spatial indicator maps. In this contribution, we aim to: 1) evaluate the geometric and thematic uncertainties of the impervious areas extracted from remote sensing images, 2) propagate them to the spatial indicators using simulation, and 3) produce uncertainty maps for two spatial indicators: the area consumption per inhabitant, and the dispersion of impervious areas. In the region Languedoc-Roussillon, which covers 27,376 km 2 in the south of France, a methodology exists to obtain impervious polygons by segmentation and classification (S dataset) of 5 m resolution RapidEye imagery. Reference impervious polygons (R dataset) were digitalized on the RapidEye images for 75 randomly selected municipalities. The segmentation accuracy was evaluated using the intersection area of S and R, and the boundary distance distribution signature (BDDS) (Huang and Dom 1995). The BDDS is the histogram of the distance between each vertex of S to the closest vertex of R, calculated using only the polygons of S having more than 50% area overlap with R. In a Monte-Carlo set up, 1,000 simulations of impervious polygons were generated using Gaussian random fields of polar coordinates of the polygon vertices. The corresponding 1,000 spatial indicator maps allowed mapping the uncertainties and calculating confidence intervals for each indicator of urban sprawl

APPLICATION DU MODELE STATISTIQUE A L'ETUDE DES FONCTIONS D'EXCITATION (α, xn) SUR L'HOLMIUM ET LE THULIUM

Les mesures des fonctions d'excitation (α, xn) sur 169Tm et 165Ho ont été complétées jusqu'à 150 MeV. Ces résultats expérimentaux nous servent de test pour deux types de calcul : - Modèle statistique à l'équilibre avec une expression de la densité de niveau tenant compte du moment angulaire. - Modèle statistique avant équilibre ou précomposé. Le second modèle est satisfaisant pour les réactions (α, xn) avec x = 1 à 4. Cette analyse a aussi été appliquée à des résultats déjà publiés : reactions (p, xn) sur 181Ta et (12C, xn) sur 142Nd pour contrôler certains paramètres.Cross sections of reactions (α, xn) induced by alpha particles on 169Tm and 165Ho were measured up to 150 MeV. Excitation functions have been calculated in terms of statistical theory using a spin dependent level density parameter and the preequilibrium model of Griffin. Calculations were also performed for the 181Ta (p, xn) and 142Nd (12C, xn) excitations functions

Projet PhytoCOTE - Évaluation de la pression phytosanitaire et des risques de contamination des eaux de surface sur la zone d'étude

National audienceThis communication is part of the presentation of the results of axis 1 of the PhytoCOTE project concerning the evaluation of phytosanitary pressure and the contribution of each agricultural / viticultural plot to the risks of pesticides transfers to surface waters on the basis of ' a multi-criteria analysis coupled with a GIS.Cette communication s'inscrit dans la présentation des résultats de l'axe 1 du projet PhytoCOTE concernant l'évaluation de la pression phytosanitaire et la contribution de chaque parcelle agricole/viticole aux risques de transfert des pesticides vers les eaux de surface sur la base d'une analyse multicritère couplée à un SIG. La pression phyto moyenne sur la zone d'étude est inférieure à celle de la Région : 70% des IFT calculés par exploitation viticole sont < IFT moyen régional en viticulture (16,9). Six critères ont été retenus avec pondération : Pente moyenne de la parcelle ; Type de sol (perméabilité) ; Connexion hydrologique (qualité, distance) ; Zone tampon (qualité, largeur) ; Pratiques de conduite (enherbement, travail du sol, orientation des rangs) ; Pression phytosanitaire (IFT). Des cartes de risque ont été produites sur le bassin versant expérimental dans le cadre de différents scénarios : molécules à tendance hydrophile, hydrophobes ; baisse significative de la pression phyto. La représentation graphique permet un échange constructif avec les acteurs de terrain et une bonne prise de conscience