Search

The traditional natural product discovery approach has accessed only a fraction of the chemical diversity in nature. The use of bioinformatic tools to interpret the instructions encoded in microbial biosynthetic genes has the potential to circumvent the existing methodological bottlenecks and greatly expand the scope of discovery. Structural prediction algorithms for nonribosomal peptides (NRPs), the largest family of microbial natural products, lie at the heart of this new approach. To understand the scope and limitation of the existing prediction algorithms, we evaluated their performances on NRP synthetase biosynthetic gene clusters. Our systematic analysis shows that the NRP biosynthetic landscape is uneven. Phenylglycine and its derivatives as a group of NRP building blocks (BBs), for example, have been oversampled, reflecting an extensive historical interest in the glycopeptide antibiotics family. In contrast, the benzoyl BB, including 2,3-dihydroxybenzoate (DHB), has been the most underexplored, hinting at the possibility of a reservoir of as yet unknown DHB containing NRPs with functional roles other than a siderophore. Our results also suggest that there is still vast unexplored biosynthetic diversity in nature, and the analysis presented herein shall help guide and strategize future natural product discovery campaigns. We also discuss possible ways bioinformaticians and biochemists could work together to improve the existing prediction algorithms.

This study used a driving simulator to investigate whether the presence of pedestrians and traffic engineering designs that reported to have reduction effects on overall traffic speed at intersections can facilitate drivers adopting lower impact speed behaviors at pedestrian crossings. Twenty-eight men (Mage = 39.9 yr., SD= 11.5) with drivers’ licenses participated. Nine studied measures were obtained from the speed profiles of each participant. A 14-km virtual road was presented to the participants. It included experimental scenarios of base intersection, pedestrian presence, pedestrian warning sign at intersection and in advance of intersection, and perceptual lane narrowing by hatching lines. Compared to the base intersection, the presence of pedestrians caused drivers to slow down earlier and reach a lower minimum speed before the pedestrian crossing. This speed behavior was not completely evident when adding a pedestrian warning sign at an intersection or having perceptual lane narrowing to the stop line. Additionally, installing pedestrian warning signs in advance of the intersections rather at the intersections was associated with higher impact speeds at pedestrian crossings.

A horizontal, table-sized computer display was used to examine one- and two-finger search performances. 31 college students participated in a basic computer operation and target landmark search task. The mean completion times of the target landmark search task were analyzed by a repeated-measures analysis of variance with the following factors: input device, environmental familiarity, and cue. Compared to the mouse, directly touching the computer display with one finger was inefficient when the task required more precise human-computer interactions, such as selecting small objects, or complicated tasks such as searching for targets in a computerized geographic application. However, directly touching the computer display with two fingers, one finger of each hand, appears efficient in complicated tasks. Additionally, familiar and cued environments can aid in the target landmark search task especially when searching within the cued conditions. However, the unfavorable effect of using a one-finger touch technique in searching may eliminate such cue effects.

This study examined the effects of visual-verbal load (as measured by a visually presented reading-memory task with three levels) on a visual/auditory stimulus-response task. The three levels of load were defined as follows: “No Load” meant no other stimuli were presented concurrently; “Free Load” meant that a letter (A, B, C, or D) appeared at the same time as the visual or auditory stimulus; and “Force Load” was the same as “Free Load,” but the participants were also instructed to count how many times the letter A appeared. The stimulus-response task also had three levels: “irrelevant,” “compatible,” and “incompatible” spatial conditions. These required different key-pressing responses. The visual stimulus was a red ball presented either to the left or to the right of the display screen, and the auditory stimulus was a tone delivered from a position similar to that of the visual stimulus. Participants also processed an irrelevant stimulus. The results indicated that participants perceived auditory stimuli earlier than visual stimuli and reacted faster under stimulus-response compatible conditions. These results held even under a high visual-verbal load. These findings suggest the following guidelines for systems used in driving: an auditory source, appropriately compatible signal and manual-response positions, and a visually simplified background.

A driving simulator was used to examine the effects on driving performance of auditory cues in an in-vehicle information search task. Drivers' distraction by the search tasks was measured on a peripheral detection task. The difficulty of the search task was systematically varied to test the distraction caused by a quantified visual load. 58 participants completed the task. Performance on both search tasks and peripheral detection tasks was measured by mean response time and percent error. Analyses indicated that in-vehicle information search performance can be severely degraded when a target is located within a group of diverse distractors. Inclusion of an auditory cue in the visual search increased the mean response time as a result of a change in modality from auditory to visual. Inclusion of such an auditory cue seemed to influence distraction as measured by performance on the peripheral detection task; accuracy was lower when auditory cues were provided, and responses were slower when no auditory cues were provided. Distraction by the auditory cue varied according to the difficulty of the search task.