Conflict in object affordance revealed by grip force

Viewing objects can result in automatic, partial activation of motor plans associated with them—“object affordance”. Here, we recorded grip force simultaneously from both hands in an object affordance task to investigate the effects of conflict between coactivated responses. Participants classified pictures of objects by squeezing force transducers with their left or right hand. Responses were faster on trials where the object afforded an action with the same hand that was required to make the response (congruent trials) compared to the opposite hand (incongruent trials). In addition, conflict between coactivated responses was reduced if it was experienced on the preceding trial, just like Gratton adaptation effects reported in “conflict” tasks (e.g., Eriksen flanker). This finding suggests that object affordance demonstrates conflict effects similar to those shown in other stimulus–response mapping tasks and thus could be integrated into the wider conceptual framework on overlearnt stimulus–response associations. Corrected erroneous responses occurred more frequently when there was conflict between the afforded response and the response required by the task, providing direct evidence that viewing an object activates motor plans appropriate for interacting with that object. Recording continuous grip force, as here, provides a sensitive way to measure coactivated responses in affordance tasks

Dielectric properties of La3Ga5SiO14La_{3}Ga_{5}SiO_{14} at microwave frequencies between 10K and 400K

We report measurements of dielectric permittivity and dielectric losses at microwave frequencies of Lanthanum Gallium Silicate as a function of temperature. The dielectric rod resonator method was used to evaluate the two relative permittivity tensor components eps t and eps z of this uniaxial dielectric crystal. Between 10 and 400 K, eps t varies from 18.92 to 19.65 whereas eps z ranges from 60.81 to 46.66. Around 300 K, the temperature coefficients of eps t and eps z have opposite signs and are equal to 130 and -720 ppm/K, respectively. This characteristic enables one to design a self-compensated microwave resonator presenting a low frequency temperature sensitivity. For the measured dielectric sample the dielectric losses range from 10-4 to 5.10-6 between 300 and 20 K and are actually limited by the crystal quality

Isochronism defect for various doubly rotated cut quartz resonators

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Chemical controlled dissolution of LGS samples : Comparison with quartz and GaPO4

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IR and N-IR spectrometry characterizations of LGS crystal and family

Middle and near infrared (MIR/NIR) spectrometry has been used to characterize series of samples of LGx family and GaPO$_{4}$. Since OH impurities influence the material properties, their spectroscopy is investigated in detail. The [190–3200 nm] region is measured in transmission. Furthermore, the study of spectra made at Nitrogen liquid temperature is used to follow the modification in the signature of some defects present in the lattice and induced by treatments as $\gamma$ irradiation or annealing. At least, we show that these “new” materials contain less OH-groups than quartz crystal

Investigations on LGS and LGT Crystals to realize BAW Resonators

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New investigations on the LGT crystal intended for time and frequency applications

cited By 0International audienceMaterials of the langasite family are of current interest for both Bulk Acoustic Wave and Surface Acoustic Wave devices. In particular, they could be promising solutions to Frequency and Time applications due to their g/product, two to three times higher than for the quartz crystal [1]. We have shown that this encouraging result is strongly linked to the crystal quality [2] and to the post thermal treatment which has been submitted the device. Among the numerous crystals belonging to the LGS family, LGT seems more interesting because of the best combination of quality of growth and material parameters [3, 4]. © 2010 IEEE

Complex Impedance Spectroscopy of alkali impurities in as-grown, irradiated and annealed quartz

This work compares the dielectric relaxation properties of different crystalline quartz materials, according to their source (natural or synthetics). It is shown that these relaxation properties are due to a hopping process of alkaline (Li+, Na+ and K+) impurities, located near [Al-O4]5- tetrahedra. A detailed analysis, in terms of the distribution function of the dielectric loss peak, allowed us to perfectly distinguish the different types of as-grown quartz. We show that i) the natural quartz has less stable M+ charge carriers than the synthetic materials and that ii) the homogeneity of the M+ trapping sites, created by the [Al-O4]5- tetrahedra, strongly depends on the crystal growth conditions. These features were then studied using quartz samples with different treatment conditions: as-grown, irradiated or annealed at high temperature. We propose that the irradiation greatly facilitates the M+ relaxation, by creating additional low energy M+ hosting sites, whose number depends on the source of the quartz crystals. We also show that for 100kRad irradiation, the saturation state of the defects is already reached for all the materials under consideration. Finally, we propose that irradiation followed by annealing at 450°C improve the M+ stability and homogeneity in quartz materials, compared with the as-grown materials, this trend being much more relevant for the natural than for the synthetic quartz