Bioenergy with carbon capture and storage (BECCS) is a process of extracting bioenergy from biomass, then capturing and storing the carbon to a geological reservoir. It is a negative emission technology since the biomass is produced by plants through photosynthesis that can uptake the carbon dioxide from atmosphere. To achieve the 2°C or 1.5°C climate goal, large-scale deployment of BECCS was assumed to be prominent in many previous studies. However, this caused increasing concerns on the challenges brought to water and land resources to grow the bioenergy crops. For example, existing studies have showed that irrigation to achieve considerable bioenergy crop production needed for BECCS potential comparable to the requirement of 2°C or 1.5°C climate goal would lead to severe water stress even than climate change itself.

Under this context, where and to what extent irrigation can enhance the global BECCS potential remains unknown under sustainable water use. “Here, we define it as water use securing the local and downstream water availability for conventional water use and environmental flow requirements, suppressing nonrenewable water resources withdrawal, and preventing additional water stress.” explains lead author Zhipin Ai from National institute for environmental studies, Japan.

The study was based on simulations with a spatially explicit representation of bioenergy crop plantations and water cycle in an internally consistent model framework. To quantitatively determine the constraints of irrigation water resources, the researchers designed distinct irrigation ways (unlimited irrigation, sustainable irrigation, and no irrigation) with bioenergy crops planted on land scenarios with strict land protections to prevent adverse effects on biodiversity, food production, land degradation, and desertification due to large-scale land conversion.

The study found that, under the rain fed condition, the average global BECCS potential in 2090 was 0.82-1.99 Gt C yr-1. The BECCS potential reached 1.32-3.42 Gt C yr-1 (60% and 71% increases compared to that under rainfed condition) under full irrigation, whereas under sustainable irrigation, the BECCS potential was 0.88-2.09 Gt C yr-1 (5% and 6% increases compared to that under rainfed condition). The BECCS potential under sustainable irrigation is close to the lower limit of 1.6-4.1 Gt C yr-1, which is the required amount of BECCS in 2100 that consistent with the 1.5°C or 2°C climate goal as documented in the IPCC Special Report on Global Warming of 1.5ºC.

Given the many negative environmental impacts of large-scale deployment of BECCS, the researchers suggest that comprehensive assessments of the BECCS potential that consider both potential benefits and adverse effects are necessary for simultaneously achieving the multiple sustainable development goals on climate, water, land, etc. “In addition, considering the relatively low biophysically constrained BECCS potential under sustainable water and land use scenarios, a critical reexamination of the contribution of BECCS towards achieving the Paris Agreement goal is needed.” says co-author Vera Heck from the Potsdam Institute for Climate Impact Research.

This study was supported by the Environment Research and Technology Development Fund (JPMEERF20202005, JPMEERF15S11418, and JPMEERF20211001) of the Environmental Restoration and Conservation Agency of Japan.

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In a new study, Yale researchers show that a single dose of psilocybin given to mice prompted an immediate and long-lasting increase in connections between neurons. The findings are published July 5 in the journal Neuron.

“We not only saw a 10% increase in the number of neuronal connections, but also they were on average about 10% larger, so the connections were stronger as well,” said Yale’s Alex Kwan, associate professor of psychiatry and of neuroscience and senior author of the paper.

Previous laboratory experiments had shown promise that psilocybin, as well as the anesthetic ketamine, can decrease depression. The new Yale research found that these compounds increase the density of dendritic spines, small protrusions found on nerve cells which aid in the transmission of information between neurons. Chronic stress and depression are known to reduce the number of these neuronal connections.

Using a laser-scanning microscope, Kwan and first author Ling-Xiao Shao, a postdoctoral associate in the Yale School of Medicine, imaged dendritic spines in high resolution and tracked them for multiple days in living mice. They found increases in the number of dendritic spines and in their size within 24 hours of administration of psilocybin. These changes were still present a month later. Also, mice subjected to stress showed behavioral improvements and increased neurotransmitter activity after being given psilocybin.

For some people, psilocybin, an active compound in “magic mushrooms,” can produce a profound mystical experience. The psychedelic was a staple of religious ceremonies among indigenous populations of the New World and is also a popular recreational drug.

It may be the novel psychological effects of psilocybin itself that spurs the growth of neuronal connections, Kwan said.

“It was a real surprise to see such enduring changes from just one dose of psilocybin,” he said. “These new connections may be the structural changes the brain uses to store new experiences.”

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Materials provided by Yale University. Original written by Bill Hathaway. Note: Content may be edited for style and length.

“The number of black holes is roughly three times larger than expected from the number of stars in the cluster, and it means that more than 20% of the total cluster mass is made up of black holes. They each have a mass of about 20 times the mass of the Sun, and they formed in supernova explosions at the end of the lives of massive stars, when the cluster was still very young” says Prof Mark Gieles, from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and lead author of the paper.

Tidal streams are streams of stars that were ejected from disrupting star clusters or dwarf galaxies. In the last few years, nearly thirty thin streams have been discovered in the Milky Way halo. “We do not know how these streams form, but one idea is that they are disrupted star clusters. However, none of the recently discovered streams have a star cluster associated with them, hence we can not be sure. So, to understand how these streams formed, we need to study one with a stellar system associated with it. Palomar 5 is the only case, making it a Rosetta Stone for understanding stream formation and that is why we studied it in detail” explains Gieles.

The authors simulate the orbits and the evolution of each star from the formation of the cluster until the final dissolution. They varied the initial properties of the cluster until a good match with observations of the stream and the cluster was found. The team finds that Palomar 5 formed with a lower black hole fraction, but stars escaped more efficiently than black holes, such that the black hole fraction gradually increased. The black holes dynamically puffed up the cluster in gravitational slingshot interactions with stars, which led to even more escaping stars and the formation of the stream. Just before it completely dissolves — roughly a billion years from now — the cluster will consist entirely of black holes. “This work has helped us understand that even though the fluffy Palomar 5 cluster has the brightest and longest tails of any cluster in the Milky Way, it is not unique. Instead, we believe that many similarly puffed up, black hole-dominated clusters have already disintegrated in the Milky Way tides to form the recently discovered thin stellar streams” says co-author Dr. Denis Erkal at the University of Surrey.

Gieles points out that in this paper “we have shown that the presence of a large black hole population may have been common in all the clusters that formed the streams.” This is important for our understanding of globular cluster formation, the initial masses of stars and the evolution of massive stars. This work also has important implications for gravitational waves. “It is believed that a large fraction of binary black hole mergers form in star clusters. A big unknown in this scenario is how many black holes there are in clusters, which is hard to constrain observationally because we can not see black holes. Our method gives us a way to learn how many BHs there are in a star cluster by looking at the stars they eject.”, says Dr. Fabio Antonini from Cardiff University, a co-author of the paper.

Palomar 5 is a globular cluster discovered in 1950 by Walter Baade. It is in the Serpens constellation at a distance of about 80,000 light-years, and it is one of the roughly 150 globular clusters that orbit around the Milky Way. It is older than 10 billion years, like most other globular clusters, meaning that it formed in the earliest phases of galaxy formation. It is about 10 times less massive and 5 times more extended than a typical globular cluster and in the final stages of dissolution.

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