SciTech Roundup 2/27

CMU Research Roundup

Maybe you should go to sleep: a study of sleep and GPA

We've all heard that people should sleep between eight and 10 hours per night, but who listens? Unfortunately, a paper in Proceedings of the National Academy of Sciences predicts that students who sleep for less than 6.5 hours each night have markedly lower GPAs. In addition, for each hour of sleep lost, students experience a 0.07 decrease in end-of-term GPA, suggesting that the effects of even one night of lost sleep at the beginning of a semester can hurt a student at the end of the semester.

To quantify the impact of sleep, psychology and neuroscience professor David Cresswell worked with researchers across Carnegie Mellon, University of Pittsburgh, University of Washington, University of Virginia. They tracked the sleep times of 600 first-year students across three universities using Fitbits during the early months of the Winter/Spring term, controlling for factors such as past academic performance, daytime napping, first-generation status, and sometimes total academic course load. They found that none of these had a significant impact on the relationship between sleep and GPA. The researchers believe this shows how harmful the effects of sleep debt are academically and how difficult it is to remedy sleep debt. The researchers hope to identify an optimal time period for when early intervention could be offered to students to improve academic success.

Seed carriers that can bury themselves into soil

In reforestation, agriculture, and nature conservation, seeds often must be spread over a wide area quickly. However, some of these areas can be difficult to access. Instead, farmers and ecologists can use drones to fly into the areas and drop seeds on the ground. However, some seeds cannot simply be put on the ground. They may dry out, be exposed to too much humidity, or be eaten by birds and other wildlife. In these cases, a seed carrier called E-seed developed by researchers from the Morphing Matter Lab, directed by Lining Yao and published in "Nature," can help bury these seeds deeper into the ground.

These seed carriers are made of wood that is tightly wound around the seed, which then ends in three tails. These wooden tails unwind when exposed to water through rain or humidity; the water cause the tails to spin and drill deeper into the soil. When the rain stops or humidity lowers, the tails dry up, winding closer around the seed again. The researchers designed these carriers in consideration of the material properties, the geometries of the tails and coils, and awn topology. These carriers could be used to help improve soil quality, reduce the chances of landslides, reduce impact of invasive species, and help reforestation efforts.

Preventing devices from burning out

As electronic devices get smaller, their risks of overheating and burning out increase. Many devices have cooling systems, but there must be an interface between the electronic chip and the cooling system to most efficiently transfer heat away from the chip. To prevent this, researchers in the department of mechanical engineering, led by Sheng Shen and published in "ACS Nano," have created a special interface composed of two thin copper films with a graphene-coated copper nanowire array sandwiched between them. These copper films are Shen's earlier work called "supersolder." By coating the films in graphene, the interface can transport heat more efficiently and has decreased risk of oxidation. The interface material reduces thermal resistance by 90 percent compared to alternatives of the same thickness.

To reduce air pollution, make electrical systems more efficient

Air pollution from the fossil fuel industry kills 10.2 million people annually. One way of reducing air pollution is to increase the efficiency of the grid system. When an electrical grid is inefficient, it must generate more electricity to compensate, therefore generating more air pollution. A study published in "Energy" led by undergraduate in mechanical engineering Lauren Jenicke, investigated the loss in energy grids by comparing electricity generated and the electricity provided to citizens. They found that in many scenarios, if energy efficiency was improved by anywhere between five and 33 percent, global median emissions could be reduced by up to 40 percent.