Projecting the planned trajectory of a Level-2 automated vehicle in the windshield: Effects on human drivers' take-over response to silent failures.

To enhance the take-over performance by human drivers of Level-2 automated vehicles (AV), we developed a design concept that presents the AV's planned trajectory as augmented reality in the windshield. We hypothesized that, even when the AV does not release a take-over request before a potential crash (i.e., silent failure), the planned trajectory would allow the driver to foresee the crash and enhance the take-over performance. To test this hypothesis, we conducted a driving-simulator experiment where participants monitored the driving status of an AV with or without the planned trajectory in the context of silent failures. The results showed that, when the planned trajectory was projected in the windshield as if it were an augmented-reality display, the crash rate decreased by 10% and the take-over response time decreased by 825 ms compared to when the planned trajectory was not provided.

Usability enhancement based on usability heuristics: An examination of the underlying mechanism utilizing the psychological-refractory-period paradigm.

User Interface (UI) design practices often abide by popular usability heuristics such as Nielsen's (1994) "10 usability heuristics for user interface design" or Gerhardt-Powals' (1996) cognitive engineering principles. To examine the underlying mechanism of user performance enhancement by following some of these usability heuristics, we compared user performance between two device conditions: one representing design practices following two selected sets of usability heuristics (experimental condition) and the other without following them (control condition). As a research framework, we adopted the psychological-refractory-period (PRP) paradigm along with the locus-of-slack logic, a well-established dual-task paradigm for examining the nature of cognitive benefits caused by experimental manipulations. Results showed that the experimental-device condition that followed the usability heuristics yielded faster performance than the control condition, especially when the stimulus-onset-asynchrony between the two tasks was long than when it was short. According to the locus-of-slack logic, these results suggest that the nature of cognitive benefits caused by following the usability heuristics is more likely to be due to shortening of the response-activation stage (rather than the response-selection stage). These findings suggest that following the two usability heuristics tends to facilitate a specific stage of the information processes more than other stages.

Electrophysiological examination of response-related interference while dual-tasking: is it motoric or attentional?

The possibility that interference between motor responses contributes to dual-task costs has long been neglected, yet is supported by several recent studies. There are two competing hypotheses regarding this response-related interference. The motor-bottleneck hypothesis asserts that the motor stage of Task 1 triggers a refractory period that delays the motor stage of Task 2. The response-monitoring hypothesis asserts that monitoring of the Task-1 motor response delays the response-selection stage of Task 2. Both hypotheses predict lengthening of Task-2 response time (RT2) when Task 1 requires motor processing relative to when it does not. However, they assume different loci for the response-related bottleneck, and therefore make different predictions regarding (a) the interaction between Task-1 motor requirement and the Task-2 difficulty effect as measured by RT2 and (b) the premotoric durations and motoric durations of Task 2 as measured by lateralized readiness potentials (LRPs). To test these predictions, we conducted two experiments manipulating the Task-1 motor requirement (Go vs. NoGo) and Task-2 response-selection difficulty, as well as the stimulus-onset asynchrony (SOA). Task-1 motor processing significantly lengthened RT2, suggesting response-related interference. Importantly, the Task-1 motor response reduced the Task-2 difficulty effect at the short SOA, indicating postponement of the Task-2 motor stage, consistent with the motor-bottleneck hypothesis. Further consistent with the motor-bottleneck hypothesis, the Task-2 LRP indicated a consistent premotoric duration of Task 2 regardless of Task-1 motor requirement. These results are difficult to reconcile with the response-monitoring hypotheses, which places the response-related bottleneck before the response-selection stage of Task 2. The results also have important implications regarding use of locus-of-slack logic in PRP studies.

Effect of Sub- and Super-critical Water Treatment on Physicochemical Properties of Porcine Skin.

Super- and sub-critical water treatments have been of interest as novel methods for protein hydrolysis. In the present study, we studied the effect of sub-critical water (Sub-H2O, 300℃, 80 bar) treatment as well as super-critical water (Super-H2O, 400℃, 280 bar) treatment on the physicochemical properties of porcine skin (PS), which has abundant collagen. Porcine skin was subjected to pre-thermal treatment by immersion in water at 70℃, and then treated with sub- or super-critical water. Physicochemical properties of the hydrolysates, such as molecular weight distribution, free amino acid content, amino acid profile, pH, color, and water content were determined. For the molecular weight distribution analysis, 1 kDa hydrolyzed porcine skin (H-PS) was produced by Super-H2O or Sub-H2O treatment. The free amino acid content was 57.18 mM and 30.13 mM after Sub-H2O and Super-H2O treatment, respectively. Determination of amino acid profile revealed that the content of Glu (22.5%) and Pro (30%) was higher after Super-H2O treatment than after Sub-H2O treatment, whereas the content of Gly (28%) and Ala (13.1%) was higher after Sub-H2O treatment. Super-H2O or Sub-H2O treatment affected the pH of PS, which changed from 7.29 (Raw) to 9.22 (after Sub-H2O treatment) and 9.49 (after Super-H2O treatment). Taken together, these results showed that Sub-H2O treatment was slightly more effective for hydrolysis than Super-H2O was. However, both Sub-H2O and Super-H2O treatments were effective processing methods for hydrolysis of PS collagen in a short time and can be regarded as a green chemistry technology.

Effects of Concentration and Reaction Time of Trypsin, Pepsin, and Chymotrypsin on the Hydrolysis Efficiency of Porcine Placenta.

This study investigated the effects of three proteases (trypsin, pepsin and chymotrypsin) on the hydrolysis efficiency of porcine placenta and the molecular weight (Mw) distributions of the placental hydrolysates. Because placenta was made up of insoluble collagen, the placenta was gelatinized by applying thermal treatment at 90 ℃ for 1 h and used as the sample. The placental hydrolyzing activities of the enzymes at varying concentrations and incubation times were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and gel permeation chromatography (GPC). Based on the SDS-PAGE, the best placental hydrolysis efficiency was observed in trypsin treatments where all peptide bands disappeared after 1 h of incubation as compared to 6 h of chymotrypsin. Pepsin hardly hydrolyzed the placenta as compared to the other two enzymes. The Mw distribution revealed that the trypsin produced placental peptides with Mw of 106 and 500 Da. Peptides produced by chymotrypsin exhibited broad ranges of Mw distribution (1-20 kDa), while the pepsin treatment showed Mw greater than 7 kDa. For comparisons of pre-treatments, the subcritical water processing (37.5 MPa and 200 ℃ of raw placenta improved the efficiency of tryptic digestions to a greater level than that of a preheating treatment (90 ℃ for 1 h). Consequently, subcritical water processing followed by enzymatic digestions has the potential of an advanced collagen hydrolysis technique.