Grooming a CAT: customizing CAT administration rules to increase response efficiency in specific research and clinical settings.

PURPOSE: To evaluate the degree to which applying alternative stopping rules would reduce response burden while maintaining score precision in the context of computer adaptive testing (CAT). DATA: Analyses were conducted on secondary data comprised of CATs administered in a clinical setting at multiple time points (baseline and up to two follow ups) to 417 study participants who had back pain (51.3%) and/or depression (47.0%). Participant mean age was 51.3 years (SD = 17.2) and ranged from 18 to 86. Participants tended to be white (84.7%), relatively well educated (77% with at least some college), female (63.9%), and married or living in a committed relationship (57.4%). The unit of analysis was individual assessment histories (i.e., CAT item response histories) from the parent study. Data were first aggregated across all individuals, domains, and time points in an omnibus dataset of assessment histories and then were disaggregated by measure for domain-specific analyses. Finally, assessment histories within a "clinically relevant range" (score ≥ 1 SD from the mean in direction of poorer health) were analyzed separately to explore score level-specific findings. METHOD: Two different sets of CAT administration rules were compared. The original CAT (CATORIG) rules required at least four and no more than 12 items be administered. If the score standard error (SE) reached a value < 3 points (T score metric) before 12 items were administered, the CAT was stopped. We simulated applying alternative stopping rules (CATALT), removing the requirement that a minimum four items be administered, and stopped a CAT if responses to the first two items were both associated with best health, if the SE was < 3, if SE change < 0.1 (T score metric), or if 12 items were administered. We then compared score fidelity and response burden, defined as number of items administered, between CATORIG and CATALT. RESULTS: CATORIG and CATALT scores varied little, especially within the clinically relevant range, and response burden was substantially lower under CATALT (e.g., 41.2% savings in omnibus dataset). CONCLUSIONS: Alternate stopping rules result in substantial reductions in response burden with minimal sacrifice in score precision.

A novel application of silicone-based flame-retardant adhesive in plywood.

A silicone-based elastomer filled with vinyl-silane treated aluminum hydroxide was used to replace conventional polyurethane-based adhesive to provide a flame-retardant adhesive for plywood. The shear strength and fire performance of such a silicone-based (SI) adhesive glued plywood (SI/plywood) were investigated and compared to those of the polyurethane-based (PU) adhesive glued plywood (PU/plywood). The shear strength of the SI/plywood [(0.92 ± 0.09) MPa] was about 63% lower than that of the PU/plywood at room temperature, but it was less sensitive to water (62% reduction for the PU/plywood and 30% reduction for the SI/plywood after hot-water immersion at 63 °C for 3 h). The fire performance of plywood was assessed by a simulated match-flame ignition test (Mydrin test), lateral ignition and flame spread test, cone calorimetry, and thermocouple measurements. With a higher burn-though resistance and thermal barrier efficiency, and lower flame spread and heat release rate, the SI/plywood exhibited a superior fire-resistance and reaction-to-fire performance and improved fire-resistance as compared to the PU/plywood. The SI adhesive generated an inorganic protective layer on the sample surface that visibly suppressed glowing and smoldering of the plywood during combustion. The SI adhesive was also combined and reinforced with cellulosic fabric (CF) or glass fabric (GF) to prepare composite plywood (SI/CF/plywood and SI/GF/plywood) with improved fire performance. The cone calorimetry and thermocouple measurements indicated that the use of CF or GF in SI/CF/plywood and SI/GF/plywood, respectively, suppressed the delamination and cracking of the composite plywood and promoted the formation of an effective thermal barrier during smoldering and flaming combustion. Particularly, the SI/GF/plywood exhibited the most effective fire barrier with no crack formation, and the lowest heat release rate among the plywood types investigated in this study.

Functionally redundant peg sensilla on the scorpion pecten.

All scorpions have two mid-ventral organs called pectines. Each pecten has thousands of pore-tipped sensilla sensitive to a variety of volatile organic and water-based stimulants. However, it was previously unknown whether individual sensilla were functionally identical or different. The information enhancement hypothesis predicts that all sensilla have similar chemosensitivities such that each is a unit of a parallel processing system. The information segmentation hypothesis states that sensilla differ in their chemosensitivities, a functional arrangement akin to the glomeruli-specific chemical detection system in the moth or human olfactory sense. In this study, we tested these hypotheses by extracellularly tip-recording sensillar responses to three aqueous tastants: 0.01 M KCl, 0.1 M citric acid, and 40% ethanol by volume. We isolated stimulation to one sensillum at a time and compared the chemoresponses. Sensilla appeared to respond similarly to the same stimulant (i.e., sensillar tip-recordings revealed activity of the same cell types), although sometimes a few sensilla responded with higher spike rates than the others. We conclude that our data primarily support the information enhancement hypothesis but for future tests of sensillar function we suggest a new hybrid model, which proposes that a few specialized sensilla exist among a mostly uniform field of identical sensilla.

Protein-based ferrogels.

We present a novel synthesis in which hemoglobin and Fe(2+) react, in the presence of KNO3 and KOH, to produce protein microgels that contain magnetic iron oxide nanoparticles. The synthesis results in microgels with polymer properties (denaturing and glass transition temperatures) that are consistent with the dried protein. The iron oxide nanoparticles that exhibit an average diameter of 22nm, are ferrimagnetic, and display properties consistent with Fe3O4. The multiple functional capabilities displayed by these materials: biocompatibility, magnetism, dye uptake and controlled release, and other properties archetypal of hydrogels, will make the magnetic hydrogels attractive for a number of biomedical applications.

Electrophysiology of scorpion PEG sensilla.

We describe a modification of an existing tip-recording technique for electrophysiologically investigating short, peg-like sensory sensilla. On the mid-ventral surface of all scorpions are two appendages called pectines, which have dense fields of mechano- and chemosensory peg sensilla. One method for assessing chemoresponsiveness of these sensilla uses a tungsten electrode for extracellularly recording neural activity within a sensillum as a volatile odorant is introduced to the sensory field. The limitations of this method include slow data collection and uncontrolled stimulant introduction to, and removal from, the peg field. To overcome these limitations, we developed a new tip-recording technique that uses nonpolar mineral oil as a medium through which to deliver water-based tastants to individual peg sensilla. We have successfully applied this method to obtain sensillar chemoresponses to citric acid, ethanol, and salt. Here we describe the experimental protocol for such a study. We think this new method may be useful for studying the response properties of other arthropod chemosensory systems, including those of insects and crustaceans.

A new tip-recording method to test scorpion pecten chemoresponses to water-soluble stimulants.

On the ventral surface of all scorpions are jointed appendages called pectines, which possess thousands of sensory sensilla. Researchers have electrophysiologically examined these peg sensilla in the past, providing evidence for their chemosensitivity and intra-peg synaptic interactions. However, limits to extracellular recording and chemical stimulation have impeded further research. In this study, we develop and apply a new tip-recording technique for stimulating and recording peg neurons. Relative to previous methods in pecten electrophysiology, this technique allows for very fast and efficient data assembly. Using it, we captured sensilla chemoresponses to aqueous stimulants. We see utility in this method for advancing our understanding of sensory physiology; specifically, we suggest this technique may be useful for physiological assays on scorpion and other arthropod chemoreceptors, such as insect and crustacean gustatory sensilla.