The study reports that injecting living or even dead heart stem cells into the injured hearts of mice triggers an acute inflammatory process, which in turn generates a wound healing-like response to enhance the mechanical properties of the injured area.

Mediated by macrophage cells of the immune system, the secondary healing process provided a modest benefit to heart function after heart attack, according to Jeffery Molkentin, PhD, principal investigator, director of Molecular Cardiovascular Microbiology a Cincinnati Children’s Hospital Medical Center and a professor of the Howard Hughes Medical Institute (HHMI).

“The innate immune response acutely altered cellular activity around the injured area of the heart so that it healed with a more optimized scar and improved contractile properties,” Molkentin said. “The implications of our study are very straight forward and present important new evidence about an unsettled debate in the field of cardiovascular medicine.”

The new paper builds on a 2014 study published by the same research team, also in Nature. As in that earlier study, the current paper shows that injecting c-kit positive heart stem cells into damaged hearts as a strategy to regenerate cardiomyocytes doesn’t work. The findings prompted Molkentin and his colleagues to conclude that there is a need to “re-evaluate the current planned cell therapy based clinical trials to ask how this therapy might really work.”

An Unexpected Discovery

The study worked with two types of heart stem cells currently used in the clinical trials — bone marrow mononuclear cells and cardiac progenitor cells. As the researchers went through the process of testing and re-verifying their data under different conditions, they were surprised to discover that in addition to the two types of stem cells, injecting dead cells or even an inert chemical called zymosan also provided benefit to the heart by optimizing the healing process. Zymosan is a substance designed to induce an innate immune response.

Researchers reported that stem cells or zymosan therapies tested in this study altered immune cell responses that significantly decreased the formation of extra cellular matrix connective tissue in the injury areas, while also improving the mechanical properties of the scar itself. The authors concluded: “injected hearts produced a significantly greater change in passive force over increasing stretch, a profile that was more like uninjured hearts.”

Molkentin and his colleagues also found that stem cells and other therapeutic substances like zymosan have to be injected directly into the hearts surrounding the area of infarction injury. This is in contrast to most past human clinical trials that for patient safety reasons simply injected stem cells into the circulatory system.

“Most of the current trials were also incorrectly designed because they infuse cells into the vasculature,” Molkentin explained. “Our results show that the injected material has to go directly into the heart tissue flanking the infarct region. This is where the healing is occurring and where the macrophages can work their magic.”

The researchers also noted an interesting finding involving zymosan, a chemical compound that binds with select pattern recognition receptors to cause an acute innate immune response. Using zymosan to treat injured hearts in mice resulted in a slightly greater and longer-lasting benefit on injured tissues than injecting stem cells or dead cell debris.

Looking to the Future

Molkentin said he and other collaborating scientists will follow up the findings by looking for ways to leverage the healing properties of the stem cells and compounds they tested.

For example, considering how heart stem cells, cell debris and zymosan all triggered an acute innate immune response involving macrophages in the current paper, Molkentin explained they will test a theory that harnesses the selective healing properties of macrophages. This includes polarizing or biologically queuing macrophages to only have healing-like properties.

Further testing of this, he said, could therapeutically be very important for developing future treatment strategies.

This threatens the loss of the Amazon rainforest and the great ice sheets of Antarctica and Greenland, which are currently undergoing measurable and unprecedented changes much earlier than expected.

This “cascade” of changes sparked by global warming could threaten the existence of human civilisations.

Evidence is mounting that these events are more likely and more interconnected than was previously thought, leading to a possible domino effect.

In an article in the journal Nature, the scientists call for urgent action to reduce greenhouse gas emissions to prevent key tipping points, warning of a worst-case scenario of a “hothouse,” less habitable planet.

“A decade ago we identified a suite of potential tipping points in the Earth system, now we see evidence that over half of them have been activated,” said lead author Professor Tim Lenton, director of the Global Systems Institute at the University of Exeter.

“The growing threat of rapid, irreversible changes means it is no longer responsible to wait and see. The situation is urgent and we need an emergency response.”

Co-author Johan Rockström, director of the Potsdam Institute for Climate Impact Research, said: “It is not only human pressures on Earth that continue rising to unprecedented levels.

“It is also that as science advances, we must admit that we have underestimated the risks of unleashing irreversible changes, where the planet self-amplifies global warming.

“This is what we now start seeing, already at 1°C global warming.

“Scientifically, this provides strong evidence for declaring a state of planetary emergency, to unleash world action that accelerates the path towards a world that can continue evolving on a stable planet.”

In the commentary, the authors propose a formal way to calculate a planetary emergency as risk multiplied by urgency.

Tipping point risks are now much higher than earlier estimates, while urgency relates to how fast it takes to act to reduce risk.

Exiting the fossil fuel economy is unlikely before 2050, but with temperature already at 1.1°C above pre-industrial temperature, it is likely Earth will cross the 1.5°C guardrail by 2040. The authors conclude this alone defines an emergency.

Nine active tipping points:

1. Arctic sea ice
2. Greenland ice sheet
3. Boreal forests
4. Permafrost
5. Atlantic Meridional Overturning Circulation
6. Amazon rainforest
7. Warm-water corals
8. West Antarctic Ice Sheet
9. Parts of East Antarctica

The collapse of major ice sheets on Greenland, West Antarctica and part of East Antarctica would commit the world to around 10 metres of irreversible sea-level rise.

Reducing emissions could slow this process, allowing more time for low-lying populations to move.

The rainforests, permafrost and boreal forests are examples of biosphere tipping points that if crossed result in the release of additional greenhouse gases amplifying warming.

Despite most countries having signed the Paris Agreement, pledging to keep global warming well below 2°C, current national emissions pledges — even if they are met — would lead to 3°C of warming.

Although future tipping points and the interplay between them is difficult to predict, the scientists argue: “If damaging tipping cascades can occur and a global tipping cannot be ruled out, then this is an existential threat to civilization.

“No amount of economic cost-benefit analysis is going to help us. We need to change our approach to the climate problem.”

Professor Lenton added: “We might already have crossed the threshold for a cascade of inter-related tipping points.

“However, the rate at which they progress, and therefore the risk they pose, can be reduced by cutting our emissions.”

Though global temperatures have fluctuated over millions of years, the authors say humans are now “forcing the system,” with atmospheric carbon dioxide concentration and global temperature increasing at rates that are an order of magnitude higher than at the end of the last ice age.

The latest research is the result of nearly a decade’s work by University of California, Davis, researchers in anthropology and veterinary genetics, who analyzed the DNA of hundreds of dogs’ ancient skeletal remains to determine that the Inuit dog had significantly different DNA than other Arctic dogs, including malamutes and huskies.

The article, “Specialized sledge dogs accompanied the Inuit dispersal across the North American Arctic,” was published Wednesday in the Proceedings of the Royal Society B: Biological Sciences. From UC Davis, authors include Christyann Darwent, professor of anthropology; Ben Sacks, adjunct professor and director of the Mammalian Ecology and Conservation Unit, Veterinary Genetics Laboratory, School of Veterinary Medicine; and Sarah Brown, a postdoctoral researcher. Lead author Carly Ameen is an archaeologist from the University of Exeter; Tatiana Feuerborn is with the Globe Institute in Denmark and Centre for Palaeogenetics in Sweden; and Allowen Evin is at the CNRS, Université de Montpellier, Institut des Sciences de l’Evolution in Montpellier, France. The list of authors includes many others from a large number of collaborating institutions.

Qimmiit (dogs in Inuktitut) were viewed by the Inuit as particularly well-suited to long-distance hauling of people and their goods across the Arctic and consuming local resources, such as sea mammals, for food.

The unique group of dogs helped the Inuit conquer the tough terrain of the North American Arctic 2,000 years ago, researchers said. Inuit dogs are the direct ancestors of modern Arctic sled dogs, and although their appearance has continued to change over time, they continue to play an important role in Arctic communities.

Experts examined the DNA from 921 dogs and wolves who lived during the last 4,500 years. Analysis of the DNA, and the locations and time periods in which they were recovered archaeologically, shows dogs from Inuit sites occupied beginning around 2,000 years ago were genetically different from dogs already in the region.

According to Sacks “the genetic profiles of ancient dogs of the American Arctic dating to 2,000 years ago were nearly identical to those of older dogs from Siberia, but contrasted starkly with those of more ancient dogs in the Americas, providing an unusually clear and definitive picture of the canine replacement event that coincided with the expansion of Thule peoples across the American Arctic two millennia ago.”

Preserving an important history

Research confirms that native peoples maintained their own dogs. By analyzing the shape of elements from 391 dogs, the study also shows that the Inuit had larger dogs with a proportionally narrower cranium to earlier dogs belonging to pre-Inuit groups.

The National Science Foundation-funded portion of the research at UC Davis was inspired by Inuit activist and author Sheila Watt-Cloutier, who told Darwent about Inuit sled-dog culling undertaken by Canadian police in the 1950s and asked if there was a way to use scientific methods to tell the history and importance of sled dogs in the Arctic. Preservation of these distinctive Inuit dogs is likely a reflection of the highly specialized role that dogs played in both long-range transportation and daily subsistence practices in Inuit society.

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Because these materials are so new, however, it has been difficult for scientists to identify and characterize Weyl semimetals. A recent theory and modeling study from scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory may not only give researchers an easier way of finding Weyl semimetals, but also a way to more easily manipulate them for potential spintronic devices.

Previous attempts to investigate Weyl semimetals relied on a complicated technique requiring an X-ray or a laser source and carefully prepared samples. To simplify the observation of semimetals, Argonne researchers instead proposed to use the relationship between two essential properties — electronic spin and charge — to reveal the nature of the topological materials and give scientists new ways to use them.

“We want to know if there is some signature in the semimetal that we can see if we attempt to run a current through it, something that is characteristic of it being a Weyl semimetal,” said Argonne materials scientist Olle Heinonen.

To generate a charge current in the Weyl semimetal, Heinonen proposed first to inject a spin current at the interface between a normal metal and the Weyl semimetal. While the spin current involved an influx of electrons with spins pointed in a particular direction, there were no net charges injected because electrons of opposite spin were being pulled the other way.

“You can think of it like having two swimmers going opposite ways in a swimming pool, one doing the freestyle and one doing the backstroke,” he said. “There’s no net direction of swimming, but there is a net amount of freestyle.”

By moving spins preferentially from the normal metal into the Weyl semimetal, the researchers found that the semimetal needed to find ways to accommodate electrons with particular spins in its electronic structure. “You can’t just stick any electron wherever you want,” Heinonen said.

Instead, the researchers found that the electrons tend to redistribute their spins into those places that are available and energetically favorable. “You might not be able to fit all your spin into one particular electronic state, but you can fit fractional amounts of spin in different states that add up to the same amount,” Heinonen said. “Imagine if you have a wave that hits a rock; you still have the same amount of water moving, just in different directions.”

When the electron “breaks up” in this manner when it encounters the Weyl semimetal, the different resulting electronic states travel with different speeds, generating a charge current. Depending on the direction in which this current is measured — say, from top to bottom or from left to right — scientists saw different results.

“How the electron breaks up is related in a very sensitive way to the relationships between energy, momentum and spin in the magnetic Weyl semimetal,” Heinonen said. “As a result, how the direction of the charge current changes is directly related to the properties of the Weyl semimetal, allowing you to determine its topological characteristics.”

Seeing the anisotropy, or the difference in charge current when measured in different directions in the Weyl semimetal, gives researchers two pieces of information. First, it reveals the Weyl nature of the material, but perhaps more importantly it allows researchers to tune the properties of the material. “The response we see is uniquely interesting because it’s a Wey lsemimetal, and because it has this interesting anisotropic response, we can probably exploit that in some devices,” Heinonen said. “We’re out a little bit ahead of the curve as far as people actually making many Weyl semimetals, but this gives us a cheap way of testing and experimenting with a type of material that is likely to become more popular.”

A paper based on the study, “Spin-to-charge conversion in magnetic Weyl semimetals,” appeared in the Nov. 1 issue of Physical Review Letters. Argonne’s Ivar Martin, Shulei Zhang, now an Assistant Professor of Physics at Case Western Reserve University, and Anton Burkov of the University of Waterloo, also collaborated on the study.

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The informative value of natural historical collections

Historical collections of the European oyster and its surrounding fauna form the basis for the new findings. The researchers investigated a total of 1,750 oysters and more than 700 slipper limpets which all found their way into the joint project’s museums and the museums in Leiden and London between 1820 and 2018. “Our unique collection by Karl August Möbius was of key importance here. This collection documented the presence of the oyster throughout Europe around 1870,” reported Dr Dirk Brandis, head of the Zoological Museum in Kiel and private lecturer at the CAU. Möbius conducted research in Kiel during the second half of the 19th century as a zoologist and ecologist. Based on his investigations of oyster presence in domestic waters, with the concept of biocoenosis he also discovered the mutual dependence of different life forms within a community. “We used the various historical archives to prove that the slipper limpet, which was introduced, had nothing to do with the European oyster dying out, although that has been assumed for a long time,” Brandis continued.

Chronological sequence of the spread of the limpet doesn’t match oyster decline

The researchers drew this conclusion from the temporal sequences, which they were now able to trace back. “Around 200 years ago, oyster fishing in the North Sea was a flourishing business,” explained Dr Dieter Fiege from the Senckenberg Research Institute and Natural History Museum in Frankfurt. He continued: “In the years afterwards, however, the Ostrea edulis numbers declined continuously. It was assumed that the appearance of the invasive slipper limpet, Crepidula fornicata, was the reason behind the dramatic decrease in oysters, along with overfishing, cold winters or diseases.”

In actual fact, the slipper limpet — which is native to the coastlines of North America — was introduced to Europe around 1870 but its presence could only be verified after 1934. “According to our findings, the decline in numbers of the European oyster population already began in the late 19th century, so well before the invasive spread of the slipper limpet. We were able to reconstruct this decline in detail,” emphasized CAU doctoral researcher, Sarah Hayer, who is conducting research at the Zoological Museum in Kiel and who accounted for the study as the lead author. “This makes it clear that the competition by an immigrant species did not cause the European oyster to die out,” added Dr Christine Ewers-Saucedo, who was chiefly responsible for collecting and analysing the data in the study at the Zoological Museum in Kiel. The real reason why the European oyster population dramatically declined in its native habitat remains unanswered.

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More than 500 representatives of various stakeholders (expert groups) involved in the environmental impact assessment of wind turbines took part in the Leibniz-IZW survey. This group included employees of conservation agencies and government authorities, representatives of non-governmental organisations in the conservation sector, consultants, employees of wind energy companies and scientists conducting research on renewable energies or on biodiversity. The survey focused on assessments on the contribution of wind energy to the transformation of the energy system, on ecologically sustainable installation and operation of wind turbines and on possible solutions for the trade-off between tackling climate change and protecting biological diversity.

“We found both significant discrepancies and broad consensus among participants,” states Christian Voigt, department head at Leibniz-IZW and first author of the survey. “The overwhelming majority of respondents confirmed that there is a direct conflict between green electricity and bat protection. Most importantly, they considered the protection of biodiversity to be just as important as the contribution to protect the global climate through renewable energy production.” Most stakeholders agreed that small to moderate losses in the yield of wind power plants in terms of electricity production and thus in financial terms instigated by the consistent application of conservation laws must become acceptable. Possible shutdown times in electricity production should be compensated. “We will probably have to accept a higher price of green electricity for the purpose of the effective protection of bats in order to compensate for the shutdown times of wind turbines,” Voigt sums up. “This does not address the unsolved issue of how to deal with habitat loss, especially when wind turbines are placed in forests.”

The conflict between wind power projects and the objectives of biological conservation intensified in recent years because the rapidly rising number of wind plants — there are now around 30,000 on mainland Germany — has made suitable locations scarce. As a result, new plants are increasingly erected in locations where conflicts with wildlife and the protection of wildlife are more likely, for example in forests. “According to members of conservation authorities, only about 25 % of wind turbines are operated under mitigation schemes such as temporary halt of wind turbine operation during periods of high bat activity (for example during the migration season), at relatively low wind speeds and at high air temperatures even though the legal framework that protects bats would require the enforcemnt of such measures,” adds author Marcus Fritze of Leibniz-IZW. In addition, it became clear from the survey that members of the wind energy industry hold views on some aspects of the green-green dilemma that differ from those of other expert groups. “Representatives of the wind energy industry consider compliance with climate protection targets as more important than measures to protect species. All other expert groups disagree with this notion,” said Fritze. “A consistent dialogue between all participants therefore seems particularly important in order to enable ecologically sustainable wind energy production.”

The survey also showed that

• more than 95% of respondents consider the transformation of the energy system (“Energiewende”) to be important,
• all expert groups agreed on aiming for an ecologically sustainable energy transition,
• two thirds of stakeholders in the wind energy industry shared the view that wind energy production should be promoted more strongly than energy production from other renewable sources whereas 85% of representatives from the other stakeholders disagreed with this,
• 86% of the survey participants outside the wind energy sector gave green electricity no higher priority than the protection of wildlife whereas only 4% of representatives of the wind sector industry shared this opinion (almost half were undecided or consider wind power to be more important than biodiversity protection).

For the purpose of this survey, the authors selected bats as a representative group of species for all wildlife affected by wind turbines, because large numbers of bats die at turbines and they enjoy a high level of protection both nationally and internationally, and therefore play an important role in planning and approval procedures for wind turbines. Indeed, the high collision rates of bats at wind turbines may be relevant to entire bat populations. The common noctule is the most frequent victim of wind turbines; this species is rated as declining by the Federal Agency for Nature Conservation in Germany. Furthermore, the results of years of research in the department headed by Voigt at the Leibniz-IZW show that the losses affect both local bat population as well as migrating individuals. Thus, fatalities at wind turbines in Germany affect bat populations in Germany as well as populations in other European regions from where these bats originate.

On the basis of the survey results, the authors argue in favour of a stronger consideration of nature conservation objectives in the wind energy industry and for an appreciation of the targets of the conservation of biological diversity. They suggest ways in which the cooperation of those involved in the planning and operation of wind power projects can be improved that both wind energy production and the goals of biological conservation can be satisfied.

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Researchers from ETH Zurich have now used a new technique to produce complex glass objects with 3D printing. The method is based on stereolithography, one of the first 3D printing techniques developed during the 1980s. David Moore, Lorenzo Barbera, and Kunal Masania in the Complex Materials group led by ETH processor André Studart have developed a special resin that contains a plastic, and organic molecules to which glass precursors are bonded. The researchers reported their results in the latest issue of the journal Natural Materials.

Light used to “grow” objects

The resin can be processed using commercially available Digital Light Processing technology. This involves irradiating the resin with UV light patterns. Wherever the light strikes the resin, it hardens because the light sensitive components of the polymer resin cross link at the exposed points. The plastic monomers combine to form a labyrinth-like structure, creating the polymer. The ceramic-bearing molecules fill the interstices of this labyrinth.

An object can thus be built up layer by layer. The researchers can change various parameters in each layer, including pore size: weak light intensity results in large pores; intense illumination produces small pores. “We discovered that by accident, but we can use this to directly influence the pore size of the printed object,” says Masania.

The researchers are also able to modify the microstructure, layer by layer, by mixing silica with borate or phosphate and adding it to the resin. Complex objects can be made from different types of glass, or even combined in the same object using the technique.

The researchers then fire the blank produced in this way at two different temperatures: at 600?C to burn off the polymer framework and then at around 1000?C to densify the ceramic structure into glass. During the firing process, the objects shrink significantly, but become transparent and hard like window glass.

Patent application submitted

These 3D-printed glass objects are still no bigger than a die. Large glass objects, such as bottles, drinking glasses or window panes, cannot be produced in this way — which was not actually the goal of the project, emphasises Masania.

The aim was rather to prove the feasibility of producing glass objects of complex geometry using a 3D printing process. However, the new technology is not just a gimmick. The researchers applied for a patent and are currently negotiating with a major Swiss glassware dealer who wants to use the technology in his company.

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