A look at new and exciting research at UCSB.

Cosmic impacts

Asteroids and comets are well-known forms of hazardous threats to the Earth, leaving distinct craters and changes to the geologic record for scientists to study. However, another form of cosmic impacts called airbursts can be just as damaging and are far more common, yet we know little about them. James Kennett, UC Santa Barbara professor emeritus, and collaborators published a study modeling these airbursts — explosions that occur when debris like meteors enters the Earth’s atmosphere.

Airbursts that occur at altitudes less than 1000 meters and explode close to the Earth’s surface are termed “touch-down” events. The researchers created a model that would predict the effects of touch-down airbursts such as their temperatures, pressures, visible materials and bulk material failure. To test this model, they compared it to data from four real-life airburst events, including the 1945 Trinity nuclear airburst in New Mexico, an 80-meter asteroid, a 100-meter comet and a 140-meter comet. Researchers found that touch-down events can cause significant damage including destruction of buildings and ground-surface damage.

In addition, the researchers found that airbursts occurring close enough to the Earth’s surface form shallow craters. However, they can be easily covered by geological processes such as sedimentation from wind and water. This research could be potentially useful for identifying craters and impacts that resulted from touch-down airbursts. Further research is needed to create more comprehensive models and understand the impacts of airbursts.

Shark tracking

Researchers at UC Santa Barbara Benioff Ocean Science Laboratory are leading a project called SharkEye, which aims to detect and predict great white shark presence near beaches. Using drones and machine learning, a type of artificial intelligence to identify sharks in drone footage, the team is tracking shark activity at Padaro Beach. The data gathered can be used to predict when and where sharks will appear close by the shore in order to help keep local beach-goers safe.

In a recent paper by lead author Douglas McCauley of the ecology, evolution & marine biology department at UCSB and collaborators, the researchers found that sharks were more commonly sighted in the late afternoon. However, shark presence varied greatly by the time of day and year. Great white sharks often use coastal habitats that overlap with human presence and activity, and it is important to understand when and where sharks are present to help people safely share the ocean with marine life. This research can also help inform conservation efforts, as sharks are experiencing a notable decline.

Acute exercise improves cognition

UC Santa Barbara researchers in the psychological & brain sciences department recently conducted a meta-analysis of exercise research to answer the question of whether intense, short-term exercise can boost cognitive performance. While it is well established that even brief periods of exercise cause neurological changes in the brain — such as the synthesis of neurotransmitters like dopamine, GABA, acetylcholine and glutamate — most previous research has focused on the effects of long-term exercise. Although repeated long-term exercise is linked to improved cognitive function, can short-term exercise offer the same benefits?

To investigate this question, the scientists analyzed thousands of studies between 1995 and 2023 on healthy subjects from 18-45 years old by conducting a Bayesian meta-analysis. Evidence suggested that vigorous exercise had the most impact on cognitive function, specifically executive functioning. Overall, the researchers found moderate evidence that acute aerobic exercise results in a small improvement of cognitive function, especially executive function and response time. Further research is needed to understand the effects of short-term exercise on executive function processes such as decision-making.

A version of this article appeared on p.7 of the Oct. 24, 2024 edition of the Daily Nexus.