March 31, 2009,
Volume 55, No. 27
Designing A Robotic Beachcomber
Legged locomotion on flowing ground like sand or other granular media is unlike locomotion on hard ground. Feet or wheels experience both solid- and fluid-like forces as each step impacts the surface of the ground.
Now, a team of engineers from the University of Pennsylvania’s School of Engineering and Applied Science, in conjunction with Georgia Institute of Technology and Northwestern University have tested a bio-inspired robot with an improved aptitude for walking on granular surfaces, an advance for everyone from the commercial auto industry and defense industries to beachcombers.
Most living things, even cockroaches, suffer significant performance loss on flowing materials like sand. In laboratory experiments, the team studied the performance speed of a small, 2.3 kg, six-legged robot called SandBot as it ran on a bed of granular media, in this case poppy seeds.
The design, based upon the way desert animals move through sandy terrain, is an attempt to reach the perfect design, a series of robotic machines that can traverse the Earth’s, and perhaps neighboring planets’, most frustrating landscapes.
The problem is simple to visualize. If robotic, or even human limbs move too fast over granular matter they dig into the ground. Moving too slowly, while effective, has just as many drawbacks.
Researchers, including Dr. Daniel Koditschek, chair of the department of electrical and systems engineering at SEAS, seemed to have hit upon a possible solution. Desert creatures, for anyone who’s watched a tiny lizard appear to dance on hot pavement, move in herky-jerky motions and do not move over granular materials at a constant rate of speed. Instead, they tread lightly and slowly when contacting the ground, but quickly in between each step, as their legs move through the air.
Dr. Koditschek and his team tried the same thing with SandBot. With this new approach, the robot was able to traverse the makeshift sand trap 15 times faster than the Mars rovers.
By accelerating more slowly into the poppy seed bed, the robotic limbs sunk lower into the ground. Once the grains have been compacted underneath the robotic appendage, much like sand packed tightly into a beach pail, the legs slide through the sandy cavity, pushing the robot forward.
Better understanding of the physics of both a successful design and granular matter should guide development of future versions, similar to the well-developed models of aerial and aquatic craft.
Analysis of physical models such as SandBot can also inform locomotion biology in understanding how animals appear to move effortlessly across a diversity of complex substrates. Such devices will begin to have capabilities comparable with organisms seen in nature, often the most efficient designs.
Stressed Parents More Likely to Abuse Children
Socially isolated, highly stressed parents are more likely to abuse or neglect their children than are their more sociable, serene peers. Research also suggests that a strong social network can have a buffering effect on the corrosive effects of stress.
To evaluate an intervention designed to mitigate parental isolation and stress, researchers from the University of Pennsylvania’s Graduate School of Education (GSE) conducted a randomized field trial with 116 socially isolated Head Start parents, 40 of whom had a history of child maltreatment.
The Penn GSE research team—Dr. John Fantuzzo and Dr. Howard Stevenson, along with Saburah Abdul Kabir and Marlo A. Perry—presented their findings in “An Investigation of a Community-Based Intervention for Socially Isolated Parents with a History of Child Maltreatment” in the Journal of Family Violence.
The intervention, called COPE (Community Outreach through Parent Empowerment), was designed by Dr. Stevenson. A community-based program, it incorporates two major components: an informal parent support group and group-training sessions that focus on lessening parental stress through friendships and other social connections. “Whereas the content of the sessions was focused on stressors,” the authors explain, “the process of the sessions emphasized connecting isolated and vulnerable parents with other Head Start parents.”
The study revealed that, post-intervention, parents who had received the COPE training reported lower stress levels than did the control group. They were also more likely to talk with other Head Start parents and to participate with them in Head Start and other activities.
While the authors acknowledge the need for further research, the study makes a strong argument for the intervention, particularly in the Head Start context. Rather than stigmatizing and imposing a solution, it provides mental health treatment for at-risk parents and enlists their peers as leaders in its training.
Health Insurance: An Investment to Cover Young Adults
Could offering a cash bonus for not consuming more than a threshold value of medical care hold the key to providing health insurance for 19-29 year olds, who account for nearly half of all uninsured adults?
“Some young adults can’t afford to buy health insurance, but many can,” Tom Baker, professor in Penn Law, said. “Instead of forcing them to buy something they don’t value, or making others subsidize that purchase, we suggest designing a product they would be willing to pay for.”
Professor Baker, along with Peter Siegelman of the University of Connecticut Law School, have a plan they call “Tontines for the Invincibles,” which is based on an annuity scheme that was popular in the late 1800s. Tontine life insurance policies paid a deferred dividend to policyholders who survived and faithfully paid their insurance premiums for a defined period, usually 20 years. The amount of the dividend depended on how many people were left in the insurance pool when the dividend was paid. Tontine health insurance could be structured to pay a cash bonus to subscribers who never have to use their health insurance.
In their research paper, “Enticing Low Risks into the Health Insurance Pool: Tontines for the Invincibles and Other Ideas from Insurance History and Behavioral Economics,” Professors Baker and Seligman write that the tontine feature could make buying health insurance more palatable to young adults because it frames the purchase as a smart investment, rather than spending money for something they think they don’t need.
Their paper is available on the Social Science Research Network’s website at http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1350423.
For Psychiatric Services, Wait for the Beep
Two-thirds of patients referred for psychiatric services following an emergency room visit are likely to reach only an answering machine when they call for help, compared to about 20% of patients calling medical clinics with physical symptoms. Only 10% of all calls to mental health clinics in nine US cities resulted in an appointment scheduled within two weeks, according to the School of Medicine’s study published in Annals of Emergency Medicine.
“Our results indicate that even the most motivated patients will have difficulty obtaining timely appointments and pursuing treatment for mental health complaints, despite prior studies that fault patient non-compliance for poor follow-up rates for psychiatric conditions,” said lead author Dr. Karin V. Rhodes, assistant professor of emergency medicine and director of Penn’s Division of Emergency Care Policy Research.
Since emergency departments are safety net providers for uninsured and underinsured patients, they are frequently the location where mental illnesses like depression are first identified. But because emergency departments are designed to treat acute illnesses and injuries, these patients are most often referred for psychiatric care in the community.
The study findings showed that even private insurance did not ensure access: If and when a caller was able to reach clinic personnel, only 67% of privately-insured and 33% of Medicaid patients were able to make an appointment. Researchers used an “audit study” design in which trained research assistants posed as patients calling to obtain an appointment after being diagnosed with depression in a local emergency room the night before and referred for urgent follow-up to the number being called.
Results from calls to a random sample of mental health clinics in nine US cities revealed that callers were able to reach appointment personnel only 31% of the time, compared with 78% of calls to medical clinics for physical complaints. The “depressed” callers also had to make more calls overall in order to get services; 15% of successful mental health callers had to make five or more attempts before reaching clinic personnel, compared to 3% of callers with medical complaints.
When callers who reached appointment personnel could not get an appointment, due either to insurance or capacity constraints, roughly 75% received information about alternative providers, but only half of them were given a name and contact information for that provider. About 14% were referred back to an emergency department. Among callers who secured appointments, 61% had to be scheduled for during regular business hours because clinics did not offer night or weekend hours.
While it is relatively inexpensive to combine resources to outsource appointment scheduling, it is likely that mental health clinics are both short staffed and lack the financial incentives required to reduce barriers to timely appointments. The researchers say this is a troubling trend, as evidence suggests that making it easier to access depression care after an emergency department visit might be lifesaving.
“More work is needed to assess whether depressed patients, who by definition are likely feeling hopeless and low in energy, interpret these access barriers as further evidence of their inability to function or as a rejection, and the extent to which these access barriers exacerbate depression and/or lead to suicidal thoughts,” Dr. Rhodes said.