RESUMEN
In this article, we demonstrate detection and identification of ten microplastic types directly in a water sample using an identification table derived from microplastic hyperspectral images. We selected a total of fourteen wavelengths which can be used to distinguish these ten microplastic types. We enhanced the visibility of these wavelengths by computationally removing water and baseline correcting with reflectance at 1550 nm. This method avoids, prevents, and eases most of the laborious sample preparation mandatory prior to analysis with robust techniques such as Raman spectroscopy and Fourier transform infrared spectroscopy. The ten different plastics were studied in water, first separately and then in a mixture. The microplastic concentrations varied depending on microplastic type and were kept <12 mg/ml per type. Finally, detection and identification were confirmed pixel-wise in a hyperspectral image of a realistic water matrix simulant including mixtures of only a few microplastic particles. All measurements have been performed with microplastics of different sizes and irregular shapes made in-house by milling commercial pellets and sheets. It enabled the establishment of a procedure for the identification of these vicious particles in real water samples. The present measurement setup of hyperspectral imaging and method of data analysis of a mixture of microplastics directly from a water-based sample may open a path towards fast, reliable, and on-site detection.
RESUMEN
Two students were alternately presented with interspersed high-compliance requests and social comments as antecedents to low-compliance requests. An initial comparison demonstrated similar positive effects on compliance for interspersed requests and social comments. A second analysis indicated that the effectiveness of social comments for increasing compliance was related to the time interval between social comments and low-compliance requests.
RESUMEN
Three students with moderate disabilities were taught to read and match-to-sample sight words comprising stimulus sets based upon the four food groups. We taught students conditional discriminations within four four-member sets using a single-sample/four-comparison procedure. Students were taught A-B, B-C, and C-D conditional discriminations for each of the four potential stimulus classes. Subsequent probes tested for relations based upon symmetry and one-node and two-node transitivity. The performances for all students indicated that symmetric relations emerged before one-node transitive relations, and that one-node transitive relations emerged before two-node transitive relations. These results are consistent with a pattern of responding, referred to as a "nodality effect," in which relations with fewer nodes are demonstrated prior to the demonstration of relations with a greater number of nodes. These results extend this area of research to sight-word reading for students with moderate disabilities.
RESUMEN
Two studies analyzed the effects of preceding setting events on the problem behavior of students with severe disabilities. Using ABAB withdrawal designs, the occurrence versus nonoccurrence of preceding setting events was analyzed in relation to the frequency of problem behavior. Data were collected throughout a student's school day, with interventions focusing upon the elimination of setting events that occurred before school. The results indicate that (a) the occurrence of preceding setting events was related to higher frequencies of problem behavior and (b) interventions designed to eliminate preceding setting events were consistently associated with low frequencies of problem behavior.