Josslyn Johnstone

Topic

Chemistry

Plastics

Sustainability

Chlorinated paraffins, a class of toxic chemicals commonly used to soften plastic toys or make computer wires pliable, have been prohibited in Canada since 2013 due to their known health harm – but a new ��Ƶ study found they remain prevalent in many everyday household objects.

Since the chemicals, banned under the Canadian Environmental Protection Act, are still being detected at high concentrations in the dust and air of indoor environments, researchers in the department of chemistry in the Faculty of Arts & Science set out to investigate the source of these continued emissions.

They found high concentrations of short-chain chlorinated paraffins (SCCPs) in 84 of 96 indoor consumer products they tested, including electronics, children’s toys, clothing, personal care products and indoor paints. The results were published recently in the journal Environmental Science: Processes & Impacts.

Steven Kutarna

“We analyzed a wide array of household items – some newly purchased from Toronto retailers, others donated by lab volunteers – hoping to confirm that these chemicals were no longer present,” says lead author Steven Kutarna, a recent PhD graduate of the department of chemistry. “Instead, we were surprised to find chlorinated paraffins in over 87 per cent of these products that are currently marketed in Canada.”

The researchers said they were also surprised to learn that certain products contained extremely high concentrations of the chemicals. Headphones and computer wires had the highest levels, followed by plastic children’s toys and toy packaging.

“We’re particularly concerned about children’s products like teething toys because kids are putting these toys in their mouths – a direct route for exposure,” says co-author Hui Peng, an assistant professor in the department of chemistry.

The researchers note that other studies show short-chain chlorinated paraffins can cause cancer in laboratory rats and mice. They also build up in our bodies, food webs and environment. Though there are no human studies, the International Agency for Research on Cancer classifies SCCPs as possible human carcinogens. And in 2017, the Stockholm Convention listed them for elimination due to their persistence and toxicity.

Nonetheless, their total global production is huge – more than one million tonnes per year. Since the tested products were largely manufactured for an international market, chlorinated paraffins are likely also found in similar products in the U.S., Europe and beyond.

Hui Peng

While the U of T study may be the first systematic investigation of the occurrence of chlorinated paraffins in indoor products, Kutarna notes that there have also been a few studies looking at levels in specific subsets of products – for example, a recent study found that hand blenders were the source of chlorinated paraffins detected in cat food.

“By the same token, we found trace amounts of SCCPs in personal care products we tested, like skin creams and shampoos,” said Kutarna. “These levels are low enough that we suspect they originated from the containers in which these products are stored.”

Peng and Kutarna say the ongoing presence of chlorinated paraffins in consumer products is likely due to a lack of rigorous supply chain testing and monitoring.

“In Canada, SCCPs are prohibited for import, but there are still a lot of products coming in with high concentrations of these chemicals,” says Kutarna. “They pose a technical challenge to quantify, product testing is expensive and manufacturers don’t disclose them as ingredients. It’s pretty much impossible for consumers to tell if these chemicals are in products.”

Peng adds: “Think, for example, of a laptop manufacturer that purchases plastics from many different producers around the world that are not required to list these compounds in their formulations. It’s a major hurdle for regulation and it's possible that many manufacturers are unaware that their products contain SCCPs in the first place.”

Peng and Kutarna say the best thing the average consumer can do to limit exposure is minimize their use of plastics, but stress that the onus is on governments and corporations to regulate SCCPs in products.

“There needs to be better transparency in the supply chain,” says Peng. “It should be required to report the presence of chlorinated paraffins across all stages of production, and retailers should take action to remove products containing these chemicals from their shelves.

“In Canada, we have the regulatory policy in place – so it’s about stronger enforcement.”

As for next steps, Peng and Kutarna plan to continue to investigate the presence of chlorinated paraffins in indoor environments, as well as how the chemicals accumulate in fish and other marine life.

With files from the Green Science Policy Institute

High levels of 'forever chemicals' found in paper takeout containers: Study

Christopher.Sorensen — Tue, 28 Mar 2023 18:42:54 +0000

High levels of 'forever chemicals' found in paper takeout containers: Study

Christopher.Sorensen Tue, 03/28/2023 - 14:42

Cutline

(photo by Jann Huizenga/iStock/Getty Images)

Topic

Sustainability

From makeup to clothing and furniture, so-called “forever chemicals” are everywhere – including the paper bowls and containers used to package Canadian fast-food meals.

In a recent study published in Environmental Science and Technology Letters, Miriam L. Diamond, a professor in the U of T’s department of Earth sciences and School of the Environment in the Faculty of Arts & Science, and her team examined 42 paper-based wrappers and bowls – often billed as an environmentally friendly alternative to single-use plastics – collected from fast-food restaurants in Toronto.

They were looking for potentially toxic human-made perfluoroalkyl and polyfluoroalkyl substances (PFAS), of which there are more than 9,000 in the world.

The most abundant compound detected in the samples was 6:2 FTOH, or 6:2 fluorotelomer alcohol – a PFAS that is known to be toxic. Another finding: fibre-based moulded bowls that are marketed as “compostable” had PFAS levels three to 10 times higher than paper doughnut and pastry bags.

Miriam Diamond

“As Canada restricts single-use plastics in food-service ware, our research shows that what we like to think of as the better alternatives are not so safe and green after all,” Diamond says. “In fact, they may harm our health and the environment by providing a direct route to PFAS exposure – first by contaminating the food we eat, and after they’re thrown away, polluting our air and drinking water.

“The use of PFAS in food packaging is a regrettable substitution of trading one harmful option – single-use plastics – for another.”

The research team included Hui Peng, an assistant professor in the department of chemistry, and, from the department of Earth sciences, recent graduates Anna Shalin and Diwen Yang, as well as research associate Heather Schwartz-Narbonne.

Diamond says PFAS eventually end up in our bodies and the environment, where they stay.

“PFAS are complex, persistent and they don’t break down. Whatever molecule is manufactured today will be in the environment 100 years later,” says Diamond, noting these toxic chemicals are found in a host of everyday products and have been linked to adverse health effects, including an increase in cancer risk, thyroid disease, cholesterol levels and decreased immune response and fertility.

“The bottom line is, there’s too much PFAS in the world and not enough restrictions around their use,” she says. “We need to get serious about replacing these substances with safer alternatives if we want to protect our health, and our planet’s health.”

As an environmental chemist and chemical management expert, Diamond is on a scientific mission to determine the most significant sources of PFAS exposure and spur action to limit their prevalence. As she puts it, there would be no “forever” if these chemicals were never used in the first place.

Samples of paper bag and fibre bowl used for takeout food were tested for PFAS (images courtesy of Miriam Diamond)

Diamond saw her research help shape policy last fall when California banned the use of PFAS in fabrics and cosmetics by 2025. This legislation builds on recent studies about PFAS in clothing and makeup that were carried out by Diamond and her colleagues at U of T and institutions around the world.

In a first-of-its-kind paper published in September 2022, the researchers analyzed children’s clothing in Canada and the United States to determine if such apparel is a significant source of PFAS exposure.

They found extremely high levels of these chemicals in school uniforms, mittens and other products marketed as stain resistant. Diamond says because clothing is worn against the skin, there is a higher risk of absorbing and inhaling chemical contaminants – particularly fluorotelomer alcohols, the primary type of PFAS measured in the uniforms.

“We're running an experiment right now on kids’ exposure to PFAS. There's insufficient information on the harm posed by the chemicals that are going into these products,” Diamond says. “I don’t know any parent who values stain repellency over their child’s health.”

Diamond notes that PFAS management is becoming a priority in Canada. In 2021, Environment Canada announced it was gathering evidence to address designating PFAS as a class, rather than as individual compounds as part of the federal government’s chemicals management plan. Such designations are important for enabling efficient regulatory practices. The action includes investing in research such as Diamond’s to collect information about sources of the chemicals and levels in the environment through 2023.

“We know where PFAS is used, but we don’t know what the biggest sources of environmental and human contamination are,” Diamond says.

She adds that exposure science has shown high levels of these chemicals in personal care products. So, Diamond and the team investigated PFAS levels in cosmetics in 2021, testing 231 cosmetic products. They found the highest concentration of PFAS in foundations, mascaras and lip products – particularly those that were labelled “wear-resistant,” “long-lasting” or “waterproof.”

“Focusing our attention on cosmetics as a potentially significant route to PFAS was a no-brainer,” she says. “You’re putting them right on your skin, near your eyes, your tear ducts, on your mouth ... is your beauty worth the risk to your health?”

Next, she is turning her attention to building materials such as outdoor durable paints and sealants for concrete and wood, and textiles used in outdoor settings like patio furniture.

“The problem with PFAS is that it is not labelled as an ingredient, so if you want to limit your use of certain products that contain these chemicals, you usually don’t even know what these are,” says Diamond. “That’s when buzzwords will tip you off – like stain-resistant and waterproof. But this vigilance shouldn’t fall only to the consumer.

“In Canada, we need to strengthen chemicals management to improve the health and safety for ourselves and for the next generations. That means better corporate responsibility and government regulations.”

Astronomer Lamiya Mowla breaks down 'remarkable' new Webb telescope image

Christopher.Sorensen — Fri, 17 Feb 2023 20:21:31 +0000

Astronomer Lamiya Mowla breaks down 'remarkable' new Webb telescope image

Christopher.Sorensen Fri, 02/17/2023 - 15:21

Cutline

Credits: NASA, ESA, CSA, I. Labbe (Swinburne University of Technology) and R. Bezanson (University of Pittsburgh). Image processing: Alyssa Pagan (STScI).

Dunlap Institute for Astronomy & Astrophysics

Topic

Our Community

Anne Tanenbaum Centre for Jewish Studies

Space

Astronomers have revealed the latest deep-field image from NASA’s James Webb Space Telescope, featuring never-before-seen details in a region of space named Pandora’s Cluster.

The new view stitches together four Webb snapshots into one panoramic image, featuring several massive galaxy clusters merging into one megacluster. It also uncovers roughly 50,000 sources of near-infrared light.

Lamiya Mowla

Lamiya Mowla, a post-doctoral researcher at the Dunlap Institute for Astronomy & Astrophysics in the ��Ƶ’s Faculty of Arts & Science, is an observational astronomer studying the earliest galaxies in the universe, and a member of the international UNCOVER program (Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization) that is investigating Pandora’s Cluster.

She also belongs to several other Webb teams, including CANUCS (Canadian NIRISS Unbiased Cluster Survey), which last year discovered the universe’s oldest star clusters in a newly revealed galaxy.

Faculty of Arts & Science writer Josslyn Johnstone recently caught up with Mowla to get her insights on the latest image, which was made publicly available on earlier this week.

How did you feel when you saw this new image and its features?

This is a special milestone for the James Webb Space Telescope. For someone who studies the morphology and structure of galaxies – their shapes, sizes and colours – the Pandora’s Cluster is remarkable because it is showing how much diversity there is in the universe. The unique morphology of each galaxy tells the story of its birth and growth. The high resolution of Webb delivers images of the highest quality and clarity we’ve ever had, and the high sensitivity of the UNCOVER program is allowing us to study this diversity in unprecedented detail.

Only Pandora’s central core has previously been studied in detail by NASA’s Hubble Space Telescope. What’s different about this image?

Webb has captured multiple shots that have been stitched together into one master image, a process called mosaicking – like taking a panoramic picture on your phone. A broader mosaic view like this one allows us to get a bigger picture (literally) of the environment that surrounds the clusters of galaxies, enabling us to study more galaxies and find the rare ones.

Last year you released the largest near-infrared image ever taken by NASA’s Hubble Space Telescope. How does the new imaging power of Webb compare to that of Hubble?

Webb can image at longer wavelengths than Hubble – more in the infrared – beyond what the human eye can see. This is important for observing the early universe since light from distant galaxies gets redder as it travels to us. It means astronomers are better able to see the earliest galaxies that are the farthest away. Webb is also much more sensitive and captures images at a much higher resolution, allowing us to find light from the earliest galaxies.

Pandora’s Cluster is a favourite observational target for astronomers due to the trick of nature known as gravitational lensing. What is this exactly?

We are using Pandora’s Cluster like a giant magnifying glass – the galaxy cluster in the foreground distorts and magnifies much more distant galaxies behind it. By bringing together the imaging power of Webb and this natural magnifying-glass-like effect, we can find objects in the early universe that we wouldn’t otherwise be able to see – even with the power of Webb on its own.

With 50,000 sources and never-before-seen features, it sounds like there is an overwhelming amount of detail to explore in this image. What are you planning to focus on for further study?

Oh yes, it is definitely a lot. I believe that Webb’s first deep field of galaxy cluster SMACS 0723 – the very first Webb image unveiled in July 2022 – has about 10,000 sources, by comparison. It’s similar to the SMACS data, but the UNCOVER program is even more remarkable because it shows three clusters merging together and spectacular features as a result.

I will use this new image to study the growth of galaxies from a very young to an adolescent universe. I am hoping to find the onset of galaxy diversity in galaxy structure – for instance, are galaxies born with very different structures? Or does the variation increase along the way as galaxies get older and have very different paths of life? However, as usual I am more excited about the unexpected!

‘Putting people front and centre’: Historian Anna Shternshis keeps Holocaust survivors' stories alive

siddiq22 — Fri, 27 Jan 2023 16:36:02 +0000

‘Putting people front and centre’: Historian Anna Shternshis keeps Holocaust survivors' stories alive

siddiq22 Fri, 01/27/2023 - 11:36

Cutline

Anna Shternshis, director of the Anne Tanenbaum Centre for Jewish Studies, explores Jewish history through the long-lost songs of Holocaust survivors (photo by Jaclyn Shapiro)

Topic

History

Music

Research

For ��Ƶ historian Anna Shternshis, understanding the past means connecting with people’s stories – or, in the case of her research, their songs.

Shternshis, director of the Anne Tanenbaum Centre for Jewish Studies and the Al and Malka Green Professor of Yiddish Studies in the department of Germanic languages and literatures in the Faculty of Arts & Science, examines Jewish culture in Russia and the Soviet Union through oral history and Yiddish culture, music and theatre.

Her 2018 project Yiddish Glory: The Lost Songs of WWII, highlights forgotten Yiddish music written during the Holocaust in the former Soviet Union. Shternshis collaborated with Russian songwriter and performer Psoy Korolenko to contextualize archival material, bringing together a global ensemble of musicians to produce a Grammy Award-nominated album. The resulting songs reveal how Jews fought against fascism, tried against all odds to save their families and expressed themselves through music.

Shternshis, who serves as special adviser on community engagement to the dean of the Faculty of Arts & Science, has continued this work, most recently collaborating with the BBC for a radio documentary exploring the long-lost wartime songs of survivors who escaped the Holocaust by fleeing to Central Asia.

She spoke to Josslyn Johnstone at the Faculty of Arts & Science and Tabassum Siddiqui at U of T News prior to the International Day of Commemoration in Memory of the Victims of the Holocaust about how survivors’ stories still resonate today.

How does International Holocaust Remembrance Day help us better understand history – and learn from the past?

Having one day of the year when we talk about an issue is not enough, but I think it’s important to have that time when we’re reminded to think about what happens to a group of people, often a minority. if they're not protected by law and by society's understanding of justice. At least there is one day when we talk about what happened to Jews in Europe – and it’s especially important in the context of university education because this is our chance to rigorously address the issue with our community of students and faculty. If not us, then who else could talk about this in a way that’s relevant? It’s important and it offers a chance to see the complexity of history by putting vulnerable individuals front and centre.

What are you trying to learn and convey about Jewish history through your research?

I’m studying how people experienced violence during the Second World War, and how they made sense of it during the war itself. I’m looking at the songs they created to document what was going on and express what they were feeling. Specifically, I’m interested in the history of the Holocaust in the Soviet Union and my focus is on people who rarely get to tell that story in their own voice. For many, music was the only way to document what was going on with them – and to leave a message for the future, which many of them did not expect to see

Anna Shternshis, top, with Yiddish Glory collaborator Psoy Korolenko (photo and design by Dan Rosenberg)

What have survivors told you about why music was a vehicle for expressing what they had been through?

In the archives that they found in Kyiv years ago, there were no stories – just songs. Survivors were terrified of telling those stories right after the war because the Soviet governmen ttreated anyone who survived the war and German occupation with suspicion, especially Jews. Survivors who had lived through hell were now afraid to go to jail for surviving. The only thing they could do was to sing because authorship of a song was not immediately attributed to them – they could just say they heard it somewhere. So, they told that story through music. History and memory are not always telling the same story.

Have you found common threads within the music they created?

In these songs, there are a lot of calls for justice; there’s also a lot of humour – they’re making fun of things that terrify us, like death or starvation. There was a sense that a lot of the people who were writing these songs would not see tomorrow. Many of these sentiments become less relevant after the war – and that’s why these songs are almost always forgotten, because people begin to worry about other things. But they give us a sense of what mattered to people there at that time.

You’re continuing your research into the songs of Holocaust survivors by looking at what happened in Central Asia during the war. Why is that region significant?

This past fall, I went to Kazakhstan and Uzbekistan with BBC Radio producer Michael Rossi – who had done a story a few years ago on my previous work – and British singer Alice Zawadzki, whose family were Polish citizens in Kazakhstan during the war. We wanted to explore the angle of those Muslim lands rescuing Jews during the Holocaust. So, she was tracing her grandmother and I was tracing the songs. And when we got there, she sang some of those songs and some of the local musicians performed with her as well. We used photographs from the United States Holocaust Memorial Museum in Washington, D.C., to see where people had gone during that time. The story is incredible – 1.4 million Soviet Jews and around 250,000 Polish Jews survived the war there. And there are a lot of descendants of those people living in Toronto today.

But when we got there, one of the takeaways for me was how the memory and knowledge of that story was just not there. We thought it would be a source of pride – that history of saving all these refugees. But because there are almost no Jews left in the region, the story is just gone. So, it felt really special to bring the songs there and sing them to remind ourselves that just because history is forgotten doesn’t mean that it didn’t happen. And in today’s world, where so many refugees are fleeing and countries are once again arguing about whether they should welcome people, it was important to go there and remember how these small countries with no resources still rescued all these Jewish families that were not welcome anywhere else in the world.

Anna Shternshis, left, and Alice Zawadzki in Bukhara, Uzbekistan during their research for a new BBC radio documentary (photo courtesy of Anna Shternshis)

Why is doing this work important to you?

I teach diaspora studies and the students and I often discuss what it’s like to be asked the question, “Where are you from?” This question rarely comes out of curiosity, but most often out of the need to assert difference or even a distrust. My research draws attention to experiences of violence among people who are “not from here,” or treated as strangers even in their own land. It is challenging to look at people as people, as opposed to just talking about numbers, processes and resources, but I argue that such an approach is crucial for understanding both the past and the present. My work is clearly connected to my personal family history as well – through my journeys, I got a little closer to understanding what my ancestors went through.

How can telling the stories of survivors help create a more equitable and inclusive society?

I think a lot about that. Racism often comes from a point of view of fear – and it’s hard to be afraid of someone who you’ve met and had a conversation with, or to see that person as a source of potential danger. Almost all mass violence happens preventively: “We’re going to kill those people so that they don’t kill us.” It’s much harder to believe those kinds of statements if you actually begin to understand the other person. Obviously, my work does not have direct policy implications, but I do think in-depth learning of those refugee experiences really helps, including talking about the history of the Holocaust and antisemitism.

Listen to Yiddish Glory on the BBC Radio 3

Smartphone app designed by U of T researchers can significantly improve memory recall

Christopher.Sorensen — Mon, 16 Jan 2023 16:13:24 +0000

Smartphone app designed by U of T researchers can significantly improve memory recall

Christopher.Sorensen Mon, 01/16/2023 - 11:13

Cutline

Psychology post-doctoral researcher Bryan Hong and Professor Morgan Barense review fMRI scans in the Toronto Neuroimaging Facility (photo by Diana Tyszko)

Topic

Memory

Psychology

Startups

UTEST

Researchers at the ��Ƶ have demonstrated that a new smartphone application helps to significantly improve memory recall, which could prove beneficial for individuals in the early stages of Alzheimer’s disease or other forms of memory impairment.

Dubbed HippoCamera for its ability to mimic the function of the brain’s hippocampus in memory construction and retention, the app enhances the encoding of memories stored in the brain by boosting attention to daily events and consolidating them more distinctly – thus later enabling richer, more comprehensive recall.

In a two-step process, HippoCamera users record a short video of up to 24 seconds of a moment they want to remember with a brief eight-second audio description of the event. The app combines the two elements just as the brain’s hippocampus would, with the video component sped up to mimic aspects of hippocampal function and to facilitate efficient review. Users then replay cues produced by HippoCamera at later times on a curated and regular basis to reinforce the memory and enable detailed recall.

“We found that memories with an associated HippoCamera cue were long-lasting, and that it worked for everyone in the study – healthy older adults, those starting to show cognitive decline and even one case with severe amnesia due to an acquired brain injury,” said study co-author Morgan Barense, a professor in the department of psychology in U of T’s Faculty of Arts & Science and Canada Research Chair in Cognitive Neuroscience.

Morgan Barense

“Many months after the initial part of the study ended, and participants had not watched their HippoCamera cues, they were able to recall these memories in rich detail.”

The study, published in the Proceedings of the National Academy of Sciences, shows that regular users of the app were able to recall over 50 per cent more details about everyday experiences that took place as many as six months earlier than if they had only recorded events and never replayed them. The new research suggests that systematic reactivation of memories for recent real-world experiences can help to maintain a bridge between the present and past in older adults and holds promise for people in the early stages of Alzheimer’s disease or other forms of memory impairment.

The study also found that reviewing memory cues with HippoCamera resulted in more positive sentiment during later retrieval.

“There’s something about being better able to remember these events that made people feel closer to them and more positive,” said Barense, who is leading the development of the app and is adjunct scientist at the Rotman Research Institute at Baycrest. “This is a really important finding given what we know about dementia and the fact that positive reminiscence or focusing on positive life events and positive emotions can improve both memory and well-being in dementia.”

The researchers measured study participants’ patterns of brain activity using fMRI, showing that recall-related brain activity in the hippocampus was more distinctive due to HippoCamera use (photo by Diana Tyszko)

For the study, participants recorded unique HippoCamera clips for everyday events that they wanted to remember and subsequently replayed these memory cues approximately eight times over a two-week period in one experiment, and over a 10-week period in a second experiment. The researchers then initiated a cued recall task where they showed the participants their memory cues and asked them to describe everything they could remember about each event.

This was followed by fMRI brain scanning sessions where researchers measured patterns of brain activity while participants saw their cues and completed a memory test. Three months later, after not practising their HippoCamera memories and not having access to the cues, the participants were asked to recall these events a second time.

“On average, we saw on later recall an increase of more than 50 per cent in the amount of rich, detailed information that someone was able to remember about events that happened as many as 200 days ago, which is significant,” said Chris Martin, an assistant professor in the department of psychology at Florida State University and lead author of the study. “Memory is truly self-sustaining ⁠– a strong memory cue can bring along another memory, which can feed into another. You just have to focus on the cue in the first place.”

Bryan Hong replays a memory cue captured using HippoCamera, which combines short audio and video clips of an event just as the hippocampus would (photo by Diana Tyszko)

The brain scans showed that replaying HippoCamera memory cues changed the way in which these everyday experiences were coded in the hippocampus, which has a well-established role in storing detailed memories for recent experiences. Recall-related activity in the hippocampus was more distinctive, meaning that HippoCamera replay helps to ensure that memories for different events remain separate from one another in the brain.

“The more detailed recollection seen earlier in the study was associated with more differentiated memory signals in the hippocampus,” said Martin. “That HippoCamera is aiding the hippocampus in distinctly encoding memories, so they do not become confused with one another, explains why users are able to recall past events in such great detail. It’s evidence that rich and detailed memory reactivation promotes memory differentiation at the neural level, and that this allows us to mentally re-experience the past with vivid detail.”

One key factor in HippoCamera’s effectiveness, the researchers say, is the sense of purpose and intention inherent in its use. By its very design, the intervention prompts users to think about what it is that they want to remember and why a particular moment is important to them – and then regularly re-engage with the memories in a meaningful way.

With an easy-to-use interface, HippoCamera is a personalized way to boost recall of daily experiences and enhance activity in the hippocampus, a part of the brain that plays a key role in memory (photo courtesy of Dynamic Memory Solutions Inc.)

“Someone who is committed to using HippoCamera is going to go through their lives paying attention to what is happening to them, asking themselves if this is an event they want to capture,” said Barense. “If it is, they’re going to take the time to stop and describe that event. And that act of approaching events in our lives with more attention is going to be good for memory.

“Then later, there’s an intention with how we study those memories, taking the time to review them using optimal learning techniques.”

The researchers note that as people begin to lose their existing memories at any point in their lives, as well as their ability to create new ones, they start to lose their sense of self. As a result, they often become disengaged from the people and events in their lives.

“Memory and our sense of identity are very closely linked,” said Barense, who is receiving support from U of T startup accelerator UTEST to take the app from lab to market. “We understand who we are as people by remembering the things that we’ve done. Our hope with HippoCamera is that by helping people feel closer to these people and events in their lives, we can help give them back their sense of self.”

The research was supported by the Canadian Institutes for Health Research, among others.

Researchers reveal a galaxy sparkling with the universe’s oldest star clusters

Christopher.Sorensen — Mon, 03 Oct 2022 13:16:22 +0000

Researchers reveal a galaxy sparkling with the universe’s oldest star clusters

Christopher.Sorensen Mon, 10/03/2022 - 09:16

Cutline

Thousands of galaxies flood this near-infrared, high-resolution image of galaxy cluster SMACS 0723 (photo courtesy of NASA, ESA, CSA, STScI.)

Topic

Dunlap Institute for Astronomy & Astrophysics

A team of Canadian astronomers, including experts from the Dunlap Institute for Astronomy & Astrophysics in the ��Ƶ's Faculty of Arts & Science, have used the James Webb Telescope (JWST) to identify the most distant globular clusters ever discovered – dense groups of millions of stars that may be relics containing the first and oldest stars in the universe.

The early analysis of Webb’s First Deep Field image, which depicts some of the universe’s earliest galaxies, was published Sept. 29 in The Astrophysical Journal Letters.

“JWST was built to find the first stars and the first galaxies and to help us understand the origins of complexity in the universe, such as the chemical elements and the building blocks of life,” says Lamiya Mowla, a post-doctoral researcher at the Dunlap Institute for Astronomy & Astrophysics and co-lead author of the study, which was carried out by the CAnadian NIRISS Unbiased Cluster Survey (CANUCS) team.

“This discovery in Webb’s First Deep Field is already providing a detailed look at the earliest phase of star formation, confirming the incredible power of JWST.”

The researchers studied the Sparkler galaxy located in Webb’s First Deep Field and used JWST to determine that five of the sparkling objects around it are globular clusters (image via Canadian Space Agency with images from NASA, ESA, CSA, STScI; Mowla, Iyer et al. 2022.)

In the finely detailed Webb’s First Deep Field image, the researchers zeroed in on what they’ve dubbed “the Sparkler galaxy,” which is nine billion light years away. This galaxy got its name for the compact objects appearing as small yellow-red dots surrounding it, referred to by the researchers as “sparkles.” The team posited that these sparkles could either be young clusters actively forming stars – born three billion years after the Big Bang at the peak of star formation – or old globular clusters. Globular clusters are ancient collections of stars from a galaxy’s infancy and contain clues about its earliest phases of formation and growth.

From their initial analysis of 12 of these compact objects, the researchers determined that five of them are not only globular clusters but among the oldest ones known.

“Looking at the first images from JWST and discovering old globular clusters around distant galaxies was an incredible moment – one that wasn’t possible with previous Hubble Space Telescope imaging,” says Kartheik G. Iyer, a post-doctoral researcher at the Dunlap Institute for Astronomy & Astrophysics and co-lead author of the study.

“Since we could observe the sparkles across a range of wavelengths, we could model them and better understand their physical properties – like how old they are and how many stars they contain. We hope the knowledge that globular clusters can be observed at from such great distances with JWST will spur further science and searches for similar objects.”

From left: Kartheik Iyer, Vince Estrada-Carpenter, Guillaume Desperez, Lamiya Mowla, Marcin Sawicki, Victoria Strait, Gabe Brammer and Kate Gould (on laptop screen), Ghassan Sarrouh, Chris Willott, Bob Abraham, Gael Noirot, Yoshi Asada, Nick Martis (photo courtesy of Lamiya Mowla and Kartheik Iyer)

The Milky Way galaxy is known to have about 150 globular clusters, but how and when exactly these dense clumps of stars formed is not well understood. Astronomers know that globular clusters can be extremely old, but it is incredibly challenging to measure their ages. Using very distant globular clusters to age-date the first stars in distant galaxies has not been done before and is only possible with JWST.

“These newly identified clusters were formed close to the first time it was even possible to form stars,” says Mowla. “Because the Sparkler galaxy is much farther away than our own Milky Way, it is easier to determine the ages of its globular clusters. We are observing the Sparkler as it was nine billion years ago, when the universe was only four-and-a-half billion years old, looking at something that happened a long time ago. Think of it as guessing a person's age based on their appearance – it’s easy to tell the difference between a five- and 10-year-old, but hard to tell the difference between a 50- and 55-year-old.”

Until now, astronomers could not see the surrounding compact objects of the Sparkler galaxy with the Hubble Space Telescope. This changed with JWST's increased resolution and sensitivity, unveiling the tiny dots surrounding the galaxy for the first time in Webb’s First Deep Field image. The Sparkler galaxy is special because it is magnified by a factor of 100 due to an effect called gravitational lensing – where the SMACS 0723 galaxy cluster in the foreground distorts what is behind it, much like a giant magnifying glass. Moreover, gravitational lensing produces three separate images of the Sparkler, allowing astronomers to study the galaxy in greater detail.

Gravitational lensing is used by astronomers to study very distant and very faint galaxies (image courtesy of NASA, ESA & L. Calçada)

“Our study of the Sparkler highlights the tremendous power in combining the unique capabilities of JWST with the natural magnification afforded by gravitational lensing,” says CANUCS team lead Chris Willott from the National Research Council’s Herzberg Astronomy and Astrophysics Research Centre. “The team is excited about more discoveries to come when JWST turns its eye on the CANUCS galaxy clusters next month.”

The researchers combined new data from JWST’s Near-Infrared Camera (NIRCam) with Hubble Scape Telescope archival data. NIRCam detects faint objects using longer and redder wavelengths to observe past what is visible to the human eye and even the Hubble Space Telescope. Both magnifications due to the lensing by the galaxy cluster and the high resolution of JWST are what made observing compact objects possible.

The Canadian-made Near-Infrared Imager and Slitless Spectrograph (NIRISS) instrument on the JWST provided independent confirmation that the objects are old globular clusters because the researchers did not observe oxygen emission lines – emissions with measurable spectra given off by young clusters that are actively forming stars. NIRISS also helped unravel the geometry of the triply lensed images of the Sparkler.

“JWST’s made-in-Canada NIRISS instrument was vital in helping us understand how the three images of the Sparkler and its globular clusters are connected,” says Marcin Sawicki, a professor at Saint. Mary's University who is Canada Research Chair in Astronomy and co-author of the study. “Seeing several of the Sparkler’s globular clusters imaged three times made it clear that they are orbiting around the Sparkler galaxy rather than being simply in front of it by chance.”

JWST will observe the CANUCS fields starting in October 2022, leveraging its data to examine five massive clusters of galaxies, around which the researchers expect to find more such systems. Future studies will also model the galaxy cluster to understand the lensing effect and execute more robust analyses to explain the star formation histories.

Collaborating institutions include York University and institutions in the United States and Europe. The research was supported by the Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada.

Fossil algae, dating from 541 million years ago, offer new insights into the plant kingdom's roots

Christopher.Sorensen — Thu, 22 Sep 2022 17:15:53 +0000

Fossil algae, dating from 541 million years ago, offer new insights into the plant kingdom's roots

Christopher.Sorensen Thu, 09/22/2022 - 13:15

Cutline

At left, the external surface of Protocodium sinense. Middle, the view through the outer layer made up of utricles. At right, the central siphons (photo by Cédric Aria)

Topic

Ecology & Evolutionary Biology

Global

Paleontologists have identified a new genus and species of algae called Protocodium sinense that predates the origin of land plants and modern animals and provides new insight into the early diversification of the plant kingdom.

Discovered at a site in China, the 541-million-year-old fossil is the first and oldest green alga from this era to be preserved in three dimensions, enabling the researchers to investigate its internal structure and identify the new specimen with unprecedented accuracy.

The study was published this week in BMC Biology, opening a window into a world of evolutionary puzzles that scientists are just beginning to unravel.

Reconstruction of a cross-section through Protocodium sinense, showing likeness to modern Codium (illustration by Shu Chai)

“Protocodium belongs to a known lineage of green algae and has a surprisingly modern architecture, showing that these algae were already well diversified before the end of the Ediacaran period,” says co-author Cédric Aria, a post-doctoral researcher in the ��Ƶ’s department of ecology and evolutionary biology in the Faculty of Arts & Science who is based at the Royal Ontario Museum (ROM).

“Its discovery touches the origin of the entire plant kingdom and puts a familiar name on the organisms that preceded the Cambrian explosion over half a billion years ago, when the world’s first modern ecosystems emerged.”

The newly discovered Protocodium fossils were found by a team led by Hong Hua, a geology professor, and post-doctoral researcher Shu Chai – both of Northwest University in Xi’an, China. It is part of the Gaojiashan biota, the name given to a significant group of exceptionally well-preserved fossils, at the Dengying Formation in Shaanxi Province. In the past 20 years, this geological formation has yielded important fossil species documenting the end of the Ediacaran Period 541-million-years ago.

Simplified phylogeny or tree of life showing the relation of Protocodium and other green algae, known as chlorophytes, to other major lineages of plants (illustration by Cédric Aria)

Organisms and their parts that do not originally absorb minerals – unlike shells or bones – require exceptional conditions to be preserved. In this case, the whole fossils and their fine cellular details were preserved in three dimensions due to the replacement of the original organic material by phosphate. This mode of preservation allowed the researchers to use various electron and X-ray microscopy techniques to virtually slice the fossil, unveil its internal structure with precision and ultimately identify it as a close relative of the modern Codium alga, a type of seaweed.

Protocodium fossils are small spheres half a millimetre wide, about the size of large grains of pollen, covered by a multitude of smaller domes. Thanks to the 3D examination, the researchers determined the domed surface to be part of a complex, single cell that contains thin strands called siphons. This morphology is typical of certain modern single-celled seaweeds that contain many nuclei.

The discovery of Protocodium would call for caution when identifying generic spherical Ediacaran fossils and may imply that organisms like Codium are in fact much older and widespread. The famous Doushantuo fossil embryos, also from China and preserved in 3D, have been at the heart of debates about the deep origin of certain animal groups. Specific stages of some of these animal-like embryos resemble the unicellular Protocodium on the outside, but 3D slicing reveals how they are composed of many cells. On the other hand, numerous 2D, round fossils of uncertain algal or other affinity are also known from the Ediacaran and older periods, but in less detail.

“We know that seaweed-like fossils are at least one billion-years-old,” says Chai, the study’s first author. “But until now, flat, grainy two-dimensional preservation has made it challenging to recognize more than general morphological structures.”

Images of Protocodium sinense using electron microscopy (A) and X-ray computed tomography (B-D). Panels B-D reveal the internal structure (image by Shu Chai, Cédric Aria and Hong Hua)

Green algae are photosynthetic organisms, which means they convert light and carbon dioxide into sugars and oxygen. They were therefore likely important foundations of Earth’s early ecosystems, and the study suggests green algae were already established in the world’s shallow waters as CO2 recyclers and oxygen producers before the Cambrian explosion.

Apart from its smaller size, Protocodium appears surprisingly identical to the modern Codium, a type of green algae found in many seas worldwide. Certain types of this seaweed are notoriously invasive – such as Codium fragile subspecies tomentosoides, dubbed “dead man’s fingers” for its appearance and spread along with commercially farmed shellfish. From an evolutionary perspective, green algae like the ancient Protocodium and land plants share a common ancestor that was thought to be about one billion to one billion and a half years old – but is now likely older since the assignment of Protocodium so close to a modern group pushes back in time the history of the entire plant kingdom.

“It’s very telling that such an organism has remained practically unchanged over at least 540 million years,” says Aria. “By the Ediacaran, evolution had driven it towards a stable adaptive zone – it’s been comfortable there since and, more than that, quite successful – so much so, in fact, that nowadays Codium takes advantage of global trade to easily outcompete other algal species.”

Funding support for the research and field work came from the National Natural Science Foundation of China and the National Key Research and Development Program. Aria’s post-doctoral fellowship is funded via the Polk Milstein Family Trust Fund (ROM) and the Natural Sciences and Engineering Research Council of Canada

PhD candidate Oksana Dudko returned to Ukraine to aid friends and family – and to 'keep the conversation alive'

Christopher.Sorensen — Wed, 31 Aug 2022 15:19:32 +0000

PhD candidate Oksana Dudko returned to Ukraine to aid friends and family – and to 'keep the conversation alive'

Christopher.Sorensen Wed, 08/31/2022 - 11:19

Cutline

Oksana Dudko, PhD candidate in history, travelled to Ukraine when the war broke out to help source and transport medical kits to friends and relatives (photo by Odri Stakhiv)

Topic

Global Lens

Global

Graduate Students

Ukraine

By Feb. 24, signs of pending Russian aggression against Oksana Dudko’s home country of Ukraine had been visible for months.

Yet the ��Ƶ graduate student says it was still a shock to open Facebook and Instagram and see her friends in Kyiv sharing the sounds of bombs falling around them.

“No one expected such a ruthless war was coming – that that would be the first day of a full-scale invasion where the whole country would be targeted,” says Dudko, a PhD candidate in the department of history who is cross-appointed to the Anne Tanenbaum Centre for Jewish Studies in the Faculty of Arts & Science.

“It’s a radical change from the Ukraine that I know.”

Many of Dudko’s friends are fighting on the front lines – specifically in Kharkiv, a city in eastern Ukraine next to the Russian border. Like much of the Ukrainian army, Dudko’s friends are not trained soldiers – they are scholars, artists and cultural workers who have volunteered to take up the fight. Some of their families are under constant shelling, hiding in basements. And, as war broke out, they were all in desperate need of medical supplies.

So Dudko, who specializes in modern Ukrainian history and 20th-century European history, left Canada for Warsaw and then onward to Lviv to help. She connected with colleagues abroad to source and transport medical kits to their friends and relatives, across the border to Lviv and throughout Ukraine. What began as an intimate effort evolved into a broader grassroots network of dedicated volunteers who delivered supplies – under rampant shelling – to civilians who were managing everything from chronic diseases to war wounds.

Left: A wrapped and reinforced Neptune fountain in Rynok Square. Across the country, Ukrainians wrapped monuments and statues to protect them from possible Russian shelling and bombardment. Lviv, May 16, 2022. Right: A Ukrainian soldier prays in St. Petro and Pavlo Garrison Church. In the background, wrapped church statues are visible. The church frequently serves as a venue for military funerals. Lviv, May 11, 2022. (photos by Oksana Dudko)

“Because Kharkiv is an active war zone, some large humanitarian convoys were not able to enter it,” says Dudko. “I’m a scholar and my colleagues are scholars who work at cultural centres like the Kharkiv Academic Puppet Theatre. We aren’t professional humanitarian volunteers. We just had this feeling that we must do anything we can to be actively involved – because it's our country, our city and our neighbourhood.”

It’s been more than six months since the war began and there’s now a more established network of humanitarian initiatives.

“Back then, we didn’t realize that the war was going to be so long,” says Dudko. “The media coverage has lessened, but war is still going on, more brutal than ever in eastern and southern Ukraine. We need to be optimistic and strong and keep helping Ukrainians in the face of what feels like a war of attrition.”

The war in Ukraine is not only deeply personal for Dudko. As a historian of the First World War and revolutions in Eastern Europe, she also understands how it is steeped in patterns of the past.

She left her home of Lviv in 2015 to pursue her PhD under the supervision of Piotr Wróbel, a professor in the department of history who holds the Konstanty Reynart Chair of Polish History. Also on her dissertation committee: University Professor Lynne Viola and Professor Doris Bergen, the Chancellor Rose and Ray Wolfe Professor of Holocaust Studies.

Dudko’s research and teaching bring her back to Ukraine often.

For many centuries, Dudko says, most of the Ukraine territories were under Russian imperial control and there were harsh policies of “Russification” – Ukrainian schools were closed and Ukrainian culture and language were forbidden. Similar restrictions continued under the Soviet Union: Ukrainians could express their ethnic identity but were not allowed any independent political life.

When Ukraine became an independent state after the collapse of the Soviet Union, Dudko says Russia tried to maintain imperial control by meddling in Ukraine’s domestic politics. “For instance, investing money in pro-Russian parties and helping pro-Russian Ukrainian politicians win elections, like former Ukrainian President Viktor Yanukovych.”

Left: A damaged residential building in Kyiv. One person died during the shelling of the area. Kyiv, May 1, 2022. Right: A tourist map of a Kyiv neighbourhood that has been painted over. Ukrainians painted over maps, road signs and street names to disorient Russian troops who invaded Ukraine. Kyiv, May 1, 2022. (photos by Oksana Dudko)

She also highlights the expansion of Russian culture across Ukraine as another method of imperial maintenance.

Ukrainians’ current efforts to protect their cultural heritage amid Russian shelling abound, with many historic monuments and street signs shrouded in protective tarps.

Saving the physical signs of Ukrainian identity are important, says Dudko, as more are lost to the war’s violence.

“We have already lost the museums that held works by local artist Maria Prymachenko and philosopher Hryhoriy Skovoroda. In the face of this destruction, many grassroots organizations such as Korydor – a magazine about contemporary culture – are performing important work to help keep independent Ukrainian culture alive.

“We can constantly see these Russian attempts to control Ukraine throughout history, and now we have this on a larger, different scale – as a full-fledged war,” Dudko says.

Prior to the invasion, Dudko taught students in Canada and Ukraine about the importance of demilitarization and diplomacy in the face of conflict – to fight for independent democracy by peaceful means.

“We can see that dialogue between countries with problematic histories is possible. There are many dark spots in Ukrainian-Polish relations. For example, Poles persecuted Ukrainians in Galicia, and later the far radical Organization of Ukrainian Nationalists participated in the massacre of Polish civilians in Volyn region during the Second World War,” Dudko explains. “Now, these countries have chosen democratic development and to work on overcoming historical traumas, so as not to repeat the same mistakes.”

But after witnessing the devastation of today’s war firsthand, with her friends and students among the many young people who have died, she says it’s difficult to reconcile that conviction.

“My generation argued for the importance of peace and demilitarization because we wanted to live in a peaceful country. Now we are in the position of having to protect it with weapons – it's a huge identity crisis,” says Dudko. “My friends who are in the army don't want to fight, don't want to kill, don’t want to die – but they don't want to live under Russian President Vladimir Putin’s regime either.

“It’s a war of survival.”

Dudko returned to Canada this summer and was joined soon after by her aunt and cousin. While she finishes her dissertation and teaches courses, she will continue to support Ukraine by collecting funds to help civilians in eastern Ukraine where much of the fighting is concentrated. She also plans to interview Ukrainian refugees and eventually create a digital archive of their experiences for the historical record.

For the rest of us who want to help, Dudko has one message: “Keep talking about Ukraine. Keep the conversation alive. Give Ukrainians your focus because it's a long war – and global solidarity matters.”

Researchers identify how cells move faster through mucus than blood

geoff.vendeville — Mon, 25 Jul 2022 16:20:57 +0000

Researchers identify how cells move faster through mucus than blood

geoff.vendeville Mon, 07/25/2022 - 12:20

Cutline

A study co-authored by U of T researchers suggests some cells travel faster in thicker fluid by using “membrane ruffling to sense changes in extracellular fluid viscosity and to trigger adaptive responses.” (photo by Mohammed Haneefa Nizamudeen/iStock)

Topic

Cell and Systems Biology

International Collaboration