Augmented Reality Based on SLAM to Assess Spatial Short-Term Memory

Spatial short-term memory is defined as the limited ability of people to retain and remember the location of elements for short periods of time. In this paper, we present the first AR app based on SLAM (Simultaneous Localization and Mapping) to assess spatial short-term memory. A total of 55 participants were involved in a study for remembering the real place where four virtual objects were located in the real environment. The participants were divided into two groups: the ARGroup (the participants learned the location of the virtual objects in the real environment in an adaptation phase using AR) and the NoARGroup (the participants learned the location of the objects by looking at photographs). The results indicated that the performance outcomes in remembering objects and their location for the participants in the ARGroup were statistically significantly greater than those obtained by the participants in the NoARGroup. From this result and our observations, we can conclude that touring the augmented environment helped the participants to better remember the location of virtual objects added to the real scene compared to looking at photographs of the environment. Furthermore, statistically significant differences were not found in relation to gender or age. Finally, our app has several advantages: 1) Our app works in any environment and does not require adding real elements to the environment; 2) the evaluators can select any real environment and place the virtual elements where they want and even change them between sessions; and 3) our app could work similar to the way spatial memory does in everyday life

Assessing the reactive surface area of soils and the association of soil organic carbon with natural oxide nanoparticles using ferrihydrite as proxy

Assessment of the surface reactivity of natural metal-(hydr)oxide nanoparticles is necessary for predicting ion adsorption phenomena in soils using surface complexation modeling. Here, we describe how the equilibrium concentrations of PO4, obtained with 0.5 M NaHCO3 extractions at different solution-to-soil ratios, can be interpreted with a state-of-the-art ion adsorption model for ferrihydrite to assess the reactive surface area (RSA) of agricultural top soils. Simultaneously, the method reveals the fraction of reversibly adsorbed soil PO4 (R-PO4). The applied ion-probing methodology shows that ferrihydrite is a better proxy than goethite for consistently assessing RSA and R-PO4. The R-PO4 pool agrees well with ammonium oxalate (AO)-extractable phosphorus, but only if measured as orthophosphate. The RSA varied between ∼2 and 20 m2/g soil. The corresponding specific surface area (SSA) of the natural metal-(hydr)oxide fraction is ∼350–1400 m2/g, illustrating that this property is highly variable and cannot be represented by a single value based on the AO-extractable oxide content. The soil organic carbon (SOC) content of our top soils increases linearly not only with the increase in RSA but remarkably also with the increase in mean particle size (1.5–5 nm). To explain these observations, we present a structural model for organo-mineral associations based on the coordination of SOC particles to metal-(hydr)oxide cores.Universidad de Costa Rica/[]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro de Investigaciones Agronómicas (CIA

A 3D serious game for dental learning in higher education

Natural User Interfaces and advanced displays can be combined to provide rich learning experiences. In this paper, we present the development and validation of a serious game that combines autostereoscopy and Natural User Interfaces for dental learning in higher education. The game includes two modes: neutral and real-world background. A comparative study to check different aspects was carried out. A total of 33 dentistry students participated in the study. From the results, the students increased significantly their knowledge about teeth morphology. Most of the students preferred the neutral background for dental learning. The real-world background was identified as being more suitable for leisure activities

Auditory and Spatial Assessment in Inattentive Children Using Smart Devices and Gesture Interaction

We present an interactive game for assessing auditory and spatial memory. We compared the performance of children with and without inattention using the game and using a variety of classical tools for assessment of auditory and spatial memory. The children with inattention showed statistically worse performance in the game. There were no statistically significant differences between the two groups for the satisfaction and interaction outcomes. Therefore, our game could be a good tool for distinguishing performances of children with and without inattention

A virtual object-location task for children: Gender and videogame experience influence navigation; age impacts memory and completion time

The use of virtual reality-based tasks for studying memory has increased considerably. Most of the studies that have looked at child population factors that influence performance on such tasks have been focused on cognitive variables. However, little attention has been paid to the impact of non-cognitive skills. In the present paper, we tested 52 typically-developing children aged 5-12 years in a virtual object-location task. The task assessed their spatial short-term memory for the location of three objects in a virtual city. The virtual task environment was presented using a 3D application consisting of a 120" stereoscopic screen and a gamepad interface. Measures of learning and displacement indicators in the virtual environment, 3D perception, satisfaction, and usability were obtained. We assessed the children's videogame experience, their visuospatial span, their ability to build blocks, and emotional and behavioral outcomes. The results indicate that learning improved with age. Significant effects on the speed of navigation were found favoring boys and those more experienced with videogames. Visuospatial skills correlated mainly with ability to recall object positions, but the correlation was weak. Longer paths were related with higher scores of withdrawal behavior, attention problems, and a lower visuospatial span. Aggressiveness and experience with the device used for interaction were related with faster navigation. However, the correlations indicated only weak associations among these variables

SLAM-based augmented reality for the assessment of short-Term spatial memory. A comparative study of visual versus tactile stimuli

The assessment of human spatial short-Term memory has mainly been performed using visual stimuli and less frequently using auditory stimuli. This paper presents a framework for the development of SLAM-based Augmented Reality applications for the assessment of spatial memory. An AR mobile application was developed for this type of assessment involving visual and tactile stimuli by using our framework. The task to be carried out with the AR application is divided into two phases: 1) a learning phase, in which participants physically walk around a room and have to remember the location of simple geometrical shapes; and 2) an evaluation phase, in which the participants are asked to recall the location of the shapes. A study for comparing the performance outcomes using visual and tactile stimuli was carried out. Fifty-Three participants performed the task using the two conditions (Tactile vs Visual), but with more than two months of difference (within-subject design). The number of shapes placed correctly was similar for both conditions. However, the group that used the tactile stimulus spent significantly more time completing the task and required significantly more attempts. The performance outcomes were independent of gender. Some significant correlations among variables related to the performance outcomes and other tests were found. The following significant correlations among variables related to the performance outcomes using visual stimuli and the participants subjective variables were also found: 1) the greater the number of correctly placed shapes, the greater the perceived competence; 2) the more attempts required, the less the perceived competence. We also found that perceived enjoyment was higher when a higher sense of presence was induced. Our results suggest that tactile stimuli are valid stimuli to exploit for the assessment of the ability to memorize spatial-Tactile associations, but that the ability to memorize spatial-visual associations is dominant. Our results also show that gender does not affect these types of memory tasks

Harmonic index and harmonic polynomial on graph operations

Some years ago, the harmonic polynomial was introduced to study the harmonic topological index. Here, using this polynomial, we obtain several properties of the harmonic index of many classical symmetric operations of graphs: Cartesian product, corona product, join, Cartesian sum and lexicographic product. Some upper and lower bounds for the harmonic indices of these operations of graphs, in terms of related indices, are derived from known bounds on the integral of a product on nonnegative convex functions. Besides, we provide an algorithm that computes the harmonic polynomial with complexity O(n 2 ).This work was supported in part by two grants from Ministerio de Economía y Competititvidad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (MTM2016-78227-C2-1-P and MTM2017-90584-REDT), Spain

Simultaneous circulation of genotypes I and III of dengue virus 3 in Colombia

<p>Abstract</p> <p>Background</p> <p>Dengue is a major health problem in tropical and subtropical regions. In Colombia, dengue viruses (DENV) cause about 50,000 cases annually, 10% of which involve Dengue Haemorrhagic Fever/Dengue Shock Syndrome. The picture is similar in other surrounding countries in the Americas, with recent outbreaks of severe disease, mostly associated with DENV serotype 3, strains of the Indian genotype, introduced into the Americas in 1994.</p> <p>Results</p> <p>The analysis of the 3'end (224 bp) of the envelope gene from 32 DENV-3 strains recently recovered in Colombia confirms the circulation of the Indian genotype, and surprisingly the co-circulation of an Asian-Pacific genotype only recently described in the Americas.</p> <p>Conclusion</p> <p>These results have important implications for epidemiology and surveillance of DENV infection in Central and South America. Molecular surveillance of the DENV genotypes infecting humans could be a very valuable tool for controlling/mitigating the impact of the DENV infection.</p

Diagnostic difficulties in congenital tumor with positive antibodies for skeletal muscle. Lipofibromatosis case report

Neonatos con Tumores congénitos de partes blandasIntroduction: Congenital soft tissue tumors are uncommon; proper diagnosis calls for histopathological experience and ancillary techniques based upon immunohistochemial, cytogenetic, and molecular biology. Following excision, intermediately aggressive soft tumors tend to local recurrence, which significantly impacts prognosis; some cases occur close to malignity; subsequently, diagnostic implications are enormous for the patient. Case report: A 26-day old neonate with a posterior left thigh mass entered hospital. Initial biopsy analysis could not rule out either striated muscle origin or malignancy; resection and classification of surgical piece followed. Pursuant to resection, using immunohistochemistry panel, tumor analysis and classification took place. Conclusion: Soft tumor diagnosis is a complex process, even more so for newborns. Infrequent occurrence requires that examiners have ample histopathological experience in the handling of ancillary techniques. Furthermore, as in lipofibromatosis, determining the presence of trapped vs. malignant tissue hinders proper classification, which, in turn, has profound implications for the patient. We include a standard diagnostic algorithm based on clinical and histological characteristics for this type of congenital lesions.https://orcid.org/0000-0003-3507-7596https://orcid.org/0000-0001-8932-4877https://orcid.org/0000-0002-7147-425Xhttps://orcid.org/0000-0001-7982-4552Revista Internacional - No indexadaN