Biomedical subjects

Nobutaka Endo

Publications and source records attributed to Nobutaka Endo.

7 recordsLinked to original sources

PubMed2005

Use of spatial context is restricted by relative position in implicit learning.

For inefficient search, target detection is faster for repeated than for regenerated layouts. This effect, called contextual cuing, was assumed to arise from implicit learning of local spatial relationships between targets and distractors. However, a more global influence from distractors far from the target has not been tested. In this study, the search field was divided into upper and lower halves containing a repeated and a regenerated configuration set, respectively. The positions of the two sets were or were not exchanged, meaning that their relative as well as their absolute positions were the same or different (Experiment 1). In Experiment 2, the repeated set appeared alone in either the same or the other half of the screen (same or different absolute position). The contextual cuing effect remained when only absolute position was changed, but not when both absolute and relative positions were changed. These results suggest that contextual cuing depends on relative positional information.

Adult↗

PubMed2004

Ion-exchange selectivity of anion exchange resin modified with polystyrenesulfonic acid.

In order to change the ion-exchange selectivity of anion-exchange resin, the surface of a gel-type anion exchange resin was modified with anionic polyelectrolyte, polystyrenesulfonic acid. Using this modified resin, the ion-exchange rate of nitrate was little decreased, but that of sulfate was evidently decreased. It is considered that the ion-exchange reaction of the multivalent anion is suppressed by the greater electrostatic repulsive force against the modification layer than that against the monovalent anion. Thus, this modified resin may be suitable for the selective separation of monovalent anions. The influence of the modified condition on the ion-exchange rate was examined. Furthermore, this modified resin was used to separate nitrate ions from sulfate ions in the aqueous solution.

Anion Exchange Resins↗

PubMed2004

Determination of vanadium in heavy oils by atomic absorption spectrometry using a graphite furnace coated with tungsten.

A simple and rapid method was established for the direct determination of vanadium in an oil sample using the tungsten-coated graphite-furnace AAS. The interference of the sulfur compound could be suppressed by choosing the ashing temperature. If the sulfur concentration in the sample is diluted to 1.0 wt% or less, the interference can be suppressed. This proposed method should make important contributions to the quality control of petroleum refineries.

Journal Article↗

PubMed2004

Selective learning of spatial configuration and object identity in visual search.

To conduct an efficient visual search, visual attention must be guided to a target appropriately. Previous studies have suggested that attention can be quickly guided to a target when the spatial configurations of search objects or the object identities have been repeated. This phenomenon is termed contextual cuing. In this study, we investigated the effect of learning spatial configurations, object identities, and a combination of both configurations and identities on visual search. The results indicated that participants could learn the contexts of spatial configurations, but not of object identities, even when both configurations and identities were completely correlated (Experiment 1). On the other hand, when only object identities were repeated, an effect of identity learning could be observed (Experiment 2). Furthermore, an additive effect of configuration learning and identity learning was observed when, in some trials, each context was the relevant cue for predicting the target (Experiment 3). Participants could learn only the context that was associated with target location (Experiment 4). These findings indicate that when multiple contexts are redundant, contextual learning occurs selectively, depending on the predictability of the target location.

Adult↗

PubMed2003

Ion-exchange properties of colloidal particle consisting of polyaniline and poly(vinyl alcohol) fixed on silica-gel powder.

A colloidal powder was prepared by fixing polyaniline (PANI, conducting polymer), poly(vinyl alcohol) (PVA, surfactant stabilizer) and a suitable dopant anion to silica-gel powder. This hydrophilic composite colloidal particle incorporates anions with the protonation of PANI in an acidic solution. The anion can be exchanged with other anions when the colloid is immersed in an acidic solution. Thus, the PANI colloid works as an ion exchanger. The ion-exchange properties on the composite colloidal powder were investigated. Anions were successfully and easily exchanged in the order Br- < Cl- < NO3- < ClO4- < SCN-. This ion-exchange selectivity corresponds largely to the ion-exchange equilibrium constants, which are based on a hydrophobic interaction between the anion and colloid. However, this ion-exchange selectivity does not agree simply with the lipophilic order, but is instead explainable by a gap in the effective ion-exchange capacity due to a size effect between the micropore on the colloidal particle formed by the dopant anion in polymerization and anion sizes in the hydrophobic environment.

Journal Article↗

PubMed2003

[Perceptual judgments of novel contour shapes and hierarchical descriptions of geometrical properties].

Previous studies of pattern psychophysics have suggested that a form property such as the number of turns and a structural property such as symmetry were useful cues for perceptual judgments of simple forms. However, it is necessary for complete descriptions of more complex forms to use hierarchical indices reflecting global and local characteristics. In this study, we clarified what geometrical properties contributed to complexity and similarity judgments of novel shapes, and examined differences between the two judgments, using Fourier descriptors as a form property, and symmetropy as a structural property. Global and local unevenness were derived from the amplitude of Fourier descriptors, and the hierarchical representation was found in both judgment data. Whereas complexity judgment was based on local unevenness and global symmetry, similarity judgment was, it was suggested, mainly based on global unevenness and symmetry. Moreover, it became clear that geometrical properties important for complexity data were a subset of those for similarity data. These results suggested that more dimensions in geometrical properties were necessary for similarity judgment than complexity judgment.

Form Perception↗

PubMed2003

[Spread of inhibition of return in visual search].

For conducting efficient visual search, it is important to inhibit spatial attention from reorienting to previously examined distractors. Several studies have proposed that this inhibition can be associated with object-based inhibition of return (IOR). The present study examined whether the spread of IOR across an object's surface affects the performance of visual search or not. If the spread of IOR occurs in visual search, unexamined targets and distractors linked with the previously attended items would be inhibited. We found that the spread of object-based IOR results in the increases of error rates in the target present trials and the decreases of reaction times in the target absent trials. These results indicate that participants made "absent" responses before examining all items if object-based IOR spread over unconfirmed items. We discuss the function of object-based IOR in visual search and also deal with how visual search is terminated.

Adolescent↗