Sound Check
Mesa Arch, Arches National Park (Photos courtesy Jeff Moore)
University of Utah geologists are using sensors to measure the soundness of the Southwest’s famed red-rock arches—with sound.
Jeff Moore, a U assistant professor of geology and geophysics, and his geohazards research group have developed “ambient resonance monitoring,” a noninvasive diagnostic process to monitor the status of arches’ structural integrity. Tracking the changes could help alert the U.S. National Park Service about when or if arches might collapse.
GOOD VIBRATIONSMoore and his team have placed clusters of small sensors— seismometers, tilt-meters, and temperature probes—on the surface of some of Utah’s most spectacular arches (including the Landscape, Mesa, and Double-O arches) in Arches and Canyonlands national parks.
One broadband seismometer is placed on or near the arch, and the other is placed about 100 meters away for reference. The seismometers are placed in cases along with a data logger and GPS clock. An electrolytic tilt-meter helps measure daily movement of the arch, while data loggers measure temperature and relative humidity.
The sensors remain on the surface for a few hours so that the vibrations and other parameters can be recorded, and then all the instruments are removed.
The sensors measure the arches’ natural vibration frequencies, which are influenced by the structures’ mass and stiffness. Those vibrations shift with rain and snow loads, thermal cycles, and internal structural damage. Moore and his team have found that each rock structure has its own characteristic resonance patterns.
The scientists repeat their measurements with the sensors to note changes in the rock structures’ frequencies over time, to help determine whether the structural integrity has changed. If an arch develops a crack, it changes the vibrational characteristics of the structure.
WALL CAME TUMBLIN’ DOWNWall Arch, in Arches National Park, collapsed in 2008 due to stress fractures that occurred over time. Moore and his team believe Landscape Arch, in the same park, is close to falling down. The 88-meter-long arch—the longest in North America—has a fundamental resonant frequency of about 1.8 Hz. If it sustains further damage, the arch’s resonant frequency would drop, and Moore and his team could measure that.
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Smart Insulin
For patients with type 1 (or “juvenile”) diabetes, the burden of constantly monitoring blood sugar and judging when and how much insulin to self-inject is difficult. Mistakes can have serious consequences. A miscalculation or lapse in regimen can cause hyperglycemia (when blood sugar levels rise too high)—potentially leading to heart disease, blindness, and other long-term complications. Or a mistake can result in hypoglycemia (when blood sugar levels plummet too low), which in the worst cases can result in coma or even death. A new “smart” insulin, developed by University of Utah researchers, could help mitigate these dangers.
Danny Hung-Chieh Chou, a U assistant professor of biochemistry and a USTAR investigator, led the research to create Ins-PBA-F, a long-lasting “smart” insulin that self-activates when blood sugar soars. Tests on mouse models for type 1 diabetes showed that one injection works for a minimum of 14 hours, during which time it was found to repeatedly and automatically lower blood sugar levels after mice were given amounts of sugar comparable to what they would consume at mealtime.
The U study was published in February in the Proceedings of the National Academies of Sciences. The researchers found that Ins-PBA-F acts more quickly and is better at lowering blood sugar than the currently available long-acting insulin drug detimir, marketed as Levimir. In fact, the speed of touching down to safe blood glucose levels was identical in the diabetic mouse models treated with Ins-PBA-F and in healthy mice whose blood sugar is regulated by their own insulin.
High-Altitude Depression
University of Utah researchers have found that the reduced oxygen experienced at high altitude can lead to depression.
In a new study, U scientists and a colleague from Tufts University learned that female rats exposed to high-altitude conditions exhibit increased depression-like behavior. (Male rats, interestingly, showed no signs of depression in the same conditions.) “The significance of this animal study is that it can isolate hypoxia as a distinct risk factor for depression in those living at altitude (hypobaric hypoxia) or with other chronic hypoxic conditions such as COPD, asthma, or smoking, independent of other risk factors,” says Shami S. Kanekar, U research assistant professor of psychiatry and lead author on the study, published in March in High Altitude Medicine and Biology online.
The correlation between altitude and high rates of depression and suicide is strikingly obvious in the Intermountain West region of the United States, where elevations are considerably higher than in the rest of the country and there is a corresponding higher rate of self-inflicted death. Several studies, including work by Perry F. Renshaw, USTAR professor of psychiatry at the U and senior author on this latest study, suggest altitude is an independent risk factor for suicide. According to Renshaw, a potential cause for depression at high altitude might be low levels of serotonin, a neurotransmitter believed to contribute to feelings of well-being and happiness. Hypoxia impairs an enzyme involved in synthesis of serotonin, likely resulting in lower levels of serotonin that could lead to depression. In addition, Renshaw’s group has shown that brain cellular metabolism can be damaged by hypoxia.