Climate change is the main cause of fires

Zhuang et al. Quantifying contributions of natural variability and anthropogenic forcings on increased fire weather risk over the western United States. Proceedings of the National Academy of Sciences. November 2021

New research showed that climate change has been the primary cause of the large wildfires in the western US that destroyed substantial land over the past two decades. Between 2001 and 2018, the size of the land destroyed every year is 13,500 square kilometers, which is twice as much as between 1984-2000. How much of this massive increase was caused by human-induced climate change and how much could be explained by natural atmospheric and climate variation have been an intensive debate. To address this major question, scientists specifically focused on the factors that control “vapor pressure deficit” (VPD), which measures the amount of moisture the air can hold when it is saturated minus the amount of moisture in the air. The greater the deficit, the more water is drawn into air from soil and plants which ultimately dry out and become conductive to fires. Strikingly, analyses of VPD data between 1979-2020 showed that 68% of the increase in VPD is due to global warming. The natural atmospheric variations were only responsible for the remaining 32% increase. These findings suggest that the western United States have passed a critical threshold in which human-induced climate warming now plays a greater role for the increase of vapor pressure deficit than natural variations in atmospheric circulation. This also shows that the effects of climate change are accelerating faster than society is equipped to deal with. And most of this rapid change seemed to have occurred since the beginning of the 21st century, much earlier than everyone anticipated. Greenhouse gases generated by human activity, primarily fossil fuel use, has already warmed our planet about 1.1 C° since the pre-industrial era. Global warming will likely continue to intensify conditions that dry out the landscape. This means, unfortunately, a higher risk of more severe fire conditions in the US and the rest of the world.

Eco-friendly flying microchips

Kim et al. Three-dimensional electronic microfliers inspired by wind-dispersed seeds. Nature. September 2021.

Engineers recently developed the smallest ever human-designed flying machine: a flying computer chip with the size of a sand grain. The main goal of the project was to develop miniaturized electronic devices to sense the environment for contamination monitoring, population surveillance or disease tracking. The team first analyzed the aerodynamics of wind-dispersed seeds of tristellateia plant and tried to understand how air flows around these microfliers. It is common for engineers to copy elements of nature to produce objects that behave in certain ways within certain environments, a concept called “biomimicry.” Tristellateia seeds have bladed wings that catch the wind to fall with a slow and rotating spin. By studying tristellateia seeds, engineers unravel the ideal structures for slow and controlled flight, which would provide the microfliers disperse over a broad area and stay in the air for a long time to better monitor the air. The microfliers consist of two major parts: millimeter-sized electronic functional components and their wings. As the microflyer falls through the air, its wings interact with the air to generate a slow, stable rotational motion. The engineers can now integrate a variety of electronics into these microchips, including circuits to detect airborne particles, sensors to monitor water quality, light detectors to measure sunlight, electronics to harvest and store energy from light, a CPU and memory, and an antenna to wirelessly transfer data to a smartphone, tablet, or computer. These miniature devices can generate massive amounts of data, but also massive amounts of garbage. Thus, the team aims to produce an environment-friendly dissolvable microlfyer. To this end, they have already started to use degradable polymers, compostable conductors and dissolvable integrated circuit chips that would naturally vanish into environmentally benign end products when exposed to water.

Targeted brain stimulation to treat mental illness

Basu et al. Closed-loop enhancement and neural decoding of cognitive control in humans. Nature Biomedical Engineering. November 2021.

A recent landmark pilot study showed that artificial intelligence merged with targeted electrical brain stimulation by brain implants can now improve specific human brain functions related to self-control and mental flexibility. Strikingly, brain implants in this new method were able to successfully sense the electrical biomarkers of cognitive deficits and respond by stimulating specific brain regions. For the study, researchers recruited 12 subjects who are undergoing brain surgery for epilepsy, in which hundreds of tiny electrodes are placed throughout the brain to record its activity and pinpoint where seizures originate. Researchers then used all this data to identify unique areas of the brain called the “internal capsule” that they believe is responsible for cognitive control. The internal capsule is thought to involve in the process of transitioning from one thought pattern or behavior to another, which is impaired in most mental illnesses. In an example of depression case, affected person typically can’t get out of a “negative thought.” An integrated machine learning algorithm also helped the team isolate the patients’ control abilities from their brain activity and their actions. At the end, the system was able to read brain activity, decode from that when a patient is having difficulty and apply a small burst of electrical stimulation to the brain to boost them past that difficulty. Researchers think this system is a lot like an electric bike. When someone is pedaling but having difficulty, the bike senses it and augments it. They have basically made the equivalent of that for human mental function. Some of the patients in the study had significant anxiety in addition to their epilepsy. When given the cognitive-enhancing stimulation, they reported that their anxiety got better, because they were more able to shift their thoughts away from their distress and focus on what they wanted. This method offers a whole new approach in treating mental illness where most interventions are typically developed to suppress symptoms. But now the new method can provide patients a tool that allows them take control of their own minds. The team is almost ready for clinical trials. Since improving cognitive control by deep brain stimulation is already approved by the FDA, translation of this care to current medical practice could be relatively faster.

Biggest extinction in Earth’s history caused by global warming—and how it could happen again

Penn JL et al. Temperature-dependent hypoxia explains biogeography and severity of end-Permian marine mass extinction. Science, December 2018.

Some 252 million years ago, long before dinosaurs, the vast majority of species on Earth were wiped out in the “Great Dying,” the worst mass extinction in our planet’s history. Up to 96% of all marine species and 70% of land animals were killed off during this event. Scientists have been trying to find the cause for this catastrophic event, which marked the end of the Permian period. One study suggested that a type of microbe spouted large amounts of methane into the atmosphere. Other studies suggested the event was triggered by a series of volcanic eruptions that released deadly amount of carbon dioxide into the air and led to cataclysmic ocean acidification. A new research study now claims that the Great Dying was primarily as a result of rapidly increasing temperatures. The researchers examined the marine fossil records and simulated the climate conditions to observe the effects of rising temperatures 252 million years ago. Researchers first ran a climate model with Earth’s configuration during the Permian period, when the tropical ocean temperatures at the surface had reached some 10 degrees Celsius (50 degrees Fahrenheit) higher. The model then reproduced dramatic changes in the oceans; oceans lost about 80 percent of their oxygen and about half the oceans’ seafloor became completely oxygen-free. To investigate the effects of these paleoclimate changes on marine species, the researchers then analyzed the varying oxygen and temperature sensitivities of 61 modern marine species including crustaceans, fish, shellfish, corals and sharks. Their calculations predicted that many marine organisms went extinct under these conditions, especially the organisms that lived far from the tropics were most sensitive to oxygen levels and they were nearly completely wiped out. To test this prediction, researchers analyzed late-Permian fossil distributions from the Paleoceanography Database and confirmed that species far from the equator suffered most during the event. The agreement between the simulations and fossils strongly suggests that climate warming and oxygen loss was a primary cause of the extinction. By 2100, warming in the upper ocean is projected to approach 20 percent of warming in the late Permian, and by the year 2300 it will reach between 35 and 50 percent. This study highlights the potential for a mass extinction arising from a similar mechanism under anthropogenic climate change. It is also a clear warning that Earth is on the path to another devastating mass extinction. According to experts, Earth could already be undergoing a sixth mass extinction that would kill off most animal and plant species. The International Union for the Conservation of Nature predicts that 99.9% of critically endangered species and 67% of endangered species will be lost within the next 100 years.

New target for therapeutic brain stimulation to treat depression found

Rao VR et al. Direct Electrical Stimulation of Lateral Orbitofrontal Cortex Acutely Improves Mood in Individuals with Symptoms of Depression. Current Biology, November 2018.

Researchers have finally found an effective target in the brain for electrical stimulation to improve mood in people suffering from depression. Stimulation of a brain region called the lateral orbitofrontal cortex (OFC) reliably produced acute improvement in mood in patients who suffered from depression. In a recent study, researchers studied 25 patients with epilepsy who had electrodes placed in the brain for medical reasons to locate the origin of their seizures. Many of those patients also suffered from depression, which is often comorbid with epilepsy. With the patients’ consent, researchers took advantage of those electrodes to deliver small electrical pulses to areas of the brain thought to be involved in regulating mood. The researchers focused their attention and the electrical stimulation on the OFC, which is a key hub for mood-related circuitry. Moreover, they specifically induced a pattern of activity in brain regions connected to OFC that was similar to patterns seen when patients naturally experienced positive mood states. The researchers applied these stimulation regimes while collecting verbal mood reports and questionnaire scores. Analyses of these reports revealed that unilateral stimulation of the lateral OFC produced acute, dose-dependent mood-state improvement in subjects with moderate-to-severe baseline depression. There is still substantial work remains to be completed before the deep brain stimulation (DBS) treatments could enter routine clinical practice. One major challenge in this study is to see whether stimulation of OFC produces durable improvement in mood over longer periods of time. Biomedical engineers hope to develop a medical device for patients with treatment-resistant mood disorders that can monitor brain activity in OFC and stimulate only when needed to keep that activity within a healthy range. Ultimately, it would be ideal if activity in mood-related brain circuits could be normalized indefinitely without patients needing to do anything.

How screen time can disrupt sleep

Mure LS et al. Sustained Melanopsin Photoresponse Is Supported by Specific Roles of β-Arrestin 1 and 2 in Deactivation and Regeneration of Photopigment. Cell Reports, 2018

For most of us, the time spent staring at screens on computers, phones and tablets adds up to many hours in a day and can often disrupt sleep. In a recent work, researchers now have pinpointed how certain cells in the eye process ambient light and reset our internal clocks, the daily cycles of physiological processes known as the circadian rhythm. When these cells are exposed to artificial light late into the night, our internal clocks can get confused, resulting in a host of health issues. A protein called melanopsin in these light-sensitive cells helps them process ambient light. Prolonged exposure to light causes melanopsin to regenerate and continuous regeneration of melanopsin triggers signals to the brain that inform it about ambient light conditions. The brain then uses this information to regulate sleep, alertness, and consciousness. In this study, the researchers turned on the production of melanopsin in retinal cells in mice and found that some of these cells are able to sustain light responses, but others lose sensitivity. Further investigations found that proteins called beta arrestin-1 and beta arrestin-2 help keep the melanopsin sensitive when exposed to light. One arrestin does its conventional job of arresting the response, and the other helps the melanopsin protein reload its retinal light-sensing co-factor. When these two steps are done in quick succession, the cell appears to respond continuously to light. This research uncovers the mechanisms behind how cells being exposed to artificial light confuses the internal body clock, and the ability to regulate sleep. It is hoped that this discovery could lead to new targets that could counter the impact of artificial light, for example by finding ways to influence melanopsin to reset the internal clock. This could lead to new treatments for insomnia, jet lag, and migraines.