Narrow-Track Agricultural Tractors: A Survey on the Load of the Hand-Operated Foldable Rollbar.
To protect the driver in case of a tractor overturn, narrow-track tractors (used in vineyards and orchards) can be equipped with a rollover protective structure (ROPS) consisting of a two-pillar front-mounted foldable rollbar. The transition from the horizontal (rest) to the vertical (protection) position of this ROPS is performed manually by the driver. In addition to the time spent performing this task many times each day, a moderate physical load is required, given that these rollbars often have a mass of some tens of kilograms. In practice, neglect and poor attention to safety lead to the foldable rollbar remaining continuously in the rest position rather than being moved to the vertical (protection) position. Several rollover accidents have been fatal for the driver because the tractor, although equipped with a two-pillar front-mounted ROPS, had the rollbar in the horizontal position at the time of the event, thus assuring no protection to the driver. This issue is quite serious. To remove at least one of the problems for the proper management of this type of ROPS, the OECD has recently updated its Code 6 by introducing an optional test addressing the manual handling of front-mounted rollbars, providing a maximum load of 100 N. Several tests were conducted on new rollbars to ascertain the accuracy of this limit. The 100 N value was generally exceeded, which is cause for criticism. Indeed, a more appropriate reference for manual handling in this case would be the higher loads (up to 250 N) already provided by other standards for non-continuous tasks.
Assessing Perceptions and Alerts of Tractor Instability
This paper presents ongoing results from a Tractor Driving Simulator study at Penn State University studying how tractor overturn events can be prevented. The simulator is used to expose subjects, in a controlled environment, to situations that would be unsafe to test in the field. Two sets of experiments are examined here. The first experiment consisted of a tilt perception study whose goal was to quantify the ability of subjects to remember and reproduce certain poses with pitch and roll angles. Nineteen subjects were individually exposed to a tilt angle; then, they used a controller to drive the simulator until they perceived they have reached the exposure angle; the process was repeated with 28 different poses representing combinations of pitch and roll of the tractor cabin. Overall, subjects reproduced angles with a smaller amplitude than they were exposed to, indicating that they were overestimating their tilt angles while actively controlling the cabin angle. Roll angles presented an overestimation of 8%, while pitch was accurately reproduced. There was no statistically significant difference between experienced tractor operators and non-experienced subjects, nor any significant influence of pitch angle on roll perception, or vice versa. The second experiment compared visual, haptic, and acoustic interfaces to alert a subject that they were driving at a hazardous roll angle. A screen with a bubble display—indicating the pitch and roll angles of the cabin—was enhanced with auditory (buzzers) and haptic (vibration on the steering wheel) alerts. When the simulator cab tilts over a pre-defined safety threshold, an alert was given to the operator along one or more alerting systems. The experiment collected the reaction times of the subjects to each type of alert interface to determine which one was the most effective at capturing the driver’s attention.
Indian Fig Cactus (Opuntia Ficus-Indica (L.) Miller) in the Americas: an Uncertain History
Abstract: 
 Opuntia ficus-indica (L.) Miller is a globally important cactus species with a long history of human use. In addition to the importance of O. ficus-indica as a food for humans and livestock, it also has long served a role in the production of cochineal, a once important textile dye. This cactus also is intimately interwoven into the story of Cactoblastis cactorum (Berg) (South American cactus moth), one of the best-known examples of biological weed control. In this regard, O. ficus-indica has been a target weed as well as an unintended host in C. cactorum invasion. Although the distribution and human-assisted movement of this cactus throughout much of the world is well documented, surprisingly little has been written about its history and movement within the Americas. Literature associated with Opuntia and their phytophagous pests in North and South America was examined in an attempt to determine the history of O. ficus-indica in the Americas. Available information suggests with some certainty that O. ficus-indica originated in present-day Mexico, but the timing of its introduction to South America is much less clear. Taxonomic difficulties associated with distinguishing among Opuntia species and the long pre-Columbian history of exchange between South American and Mesoamerican cultures are two primary complicating factors associated with dating the dispersal of this species to South America. Additionally, previous evidence in support of a pre-Columbian introduction to South America relied on questionable identification of insect-based textile dyes. These uncertainties are significant because clearer knowledge of the history of O. ficus-indica introduction to South America could provide a more complete biological and ecological context to efforts at managing this species in its native and introduced ranges, particularly with respect to the threat posed by C. cactorum in North American and Argentinean plantations.