Daniel Veghte, The Ohio State University

Sourdough is the oldest kind of leavened bread in recorded history, and people have been eating it for thousands of years. The components of creating a sourdough starter are very simple – flour and water. Mixing them produces a live culture where yeast and bacteria ferment the sugars in flour, making byproducts that give sourdough its characteristic taste and smell. They are also what make it rise in the absence of other leavening agents.

My sourdough starter, affectionately deemed the “Fosters” starter, was passed down to me by my grandparents, who received it from my grandmother's college roommate. It has followed me throughout my academic career across the country, from undergrad in New Mexico to graduate school in Pennsylvania to postdoctoral work in Washington.

Currently, it resides in the Midwest, where I work at The Ohio State University as a senior research associate, collaborating with researchers to characterize samples in a wide variety of fields ranging from food science to material science.

As part of one of the microscopy courses I instruct at the university, I decided to take a closer look at the microbial community in my family's sourdough starter with the microscope I use in my day-to-day research.

Scanning electron microscopes

Scanning electron microscopy, or SEM, is a powerful tool that can image the surface of samples at the nanometer scale. For comparison, a human hair is between 10 to 150 micrometers, and SEM can observe features that are 10,000 times smaller.

Since SEM uses electrons instead of light for imaging, there are limitations to what can be imaged in the microscope. Samples must be electrically conductive and able to withstand the very low pressures in a vacuum. Low-pressure environments are generally unfavorable for microbes, since these conditions will cause the water in cells to evaporate, deforming their structure.

To prepare samples for SEM analysis, researchers use a method called critical point drying that carefully dries the sample to reduce unwanted artifacts and preserve fine details. The sample is then coated with a thin layer of iridium metal to make it conductive.

Exploring a sourdough starter

Since sourdough starters are created from wild yeast and bacteria in the flour, it creates a favorable environment for many types of microbes to flourish. There can be more than 20 different species of yeast and 50 different species of bacteria in a sourdough starter. The most robust become the dominant species.

You can visually observe the microbial complexity of sourdough starter by imaging the different components that vary in size and morphology, including yeast and bacteria. However, a full understanding of all the diversity present in the starter would require a complete gene sequencing.

The main component that gives the starter texture are starch grains from the flour. These grains, colored green in the image, are identifiable as relatively large globular structures approximately 8 micrometers in diameter.

Giving rise to the starter is the yeast, colored red. As the yeast grows, it ferments sugars from the starch grains and releases carbon dioxide bubbles and alcohol as byproducts that make the dough rise. Yeast generally falls in the range of 2 to 10 micrometers in size and are round to elongated in shape. There are two distinct yeast types visible in this image, one that is nearly round, at the bottom left, and another that is elongated, at the top right.

Bacteria, colored blue, metabolize sugars and release byproducts such as lactic acid and acetic acid. These byproducts act as a preservative and are what give the starter its distinctive sour smell and taste. In this image, bacteria have pill-like shapes that are approximately 2 micrometers in size.

Now, the next time you eat sourdough bread or sourdough waffles – try them, they're delicious! – you can visualize the rich array of microorganisms that give each piece its distinctive flavor.

Daniel Veghte, Senior Research Associate Engineer, The Ohio State University

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Timothy Morton, Rice University

Uncommon Courses is an occasional series from The Conversation U.S. highlighting unconventional approaches to teaching.

Title of course:

What Is a Fact?

What prompted the idea for the course?

With all the conspiracy theories floating around in 2020 when COVID-19 hit, I wanted to help my students learn to identify and deal with them. I was also concerned about political propaganda. And in my STEM-heavy school, I wanted to showcase what humanities scholars can do. So I created this class, which is distilled humanities for freshmen. Almost every student so far has been a science, technology, engineering and math major.

What does the course explore?

We start with a week called What Is Data? In Latin, “data” just means “things that are given.” Data can be in the form of measurements: “This bowlful of water weighs x.” But data can also mean “it reminds me of my grandma.” How can you tell when something could be meaningful, or whether it's just nonsense?

A later class that students find especially interesting is on apophenia, the tendency to see patterns where there aren't any, like the man in the Moon, or constellations of stars.

Why is this course relevant now?

A fact is an interpretation of data. In physics class, you learn how to interpret physics data, find patterns, relate those patterns to other ones, and produce facts about them. If your argument hangs together logically, your interpretation can appear in the journal Nature Physics.

Humanities classes, however, prepare you to understand what facts are, period – whether they're based on biology or on the Bible, nutrition science or novels.

What's a critical lesson from the course?

One critical lesson is that many big conspiracy theories such as QAnon are about jumping to conclusions as quickly as possible. Being a good student and a good scholar means accepting that what you're examining might not be meaningful or might not indicate a pattern. What we're exploring here is how not to jump to conclusions. And this lesson applies as much to stuff in the real world as it does to lab work.

What materials does the course feature?

We watch YouTuber hbomberguy debunking global warming denialism. We read Kurt Gödel on how logical systems must always be flawed. We read poems and stories, introducing science majors to interpreting artistic data, a process every bit as rigorous as interpreting scientific data.

What will the course prepare students to do?

Without the kinds of critical thinking this course teaches, scientists can be susceptible to propaganda and unable to share their ideas effectively, whether it's in the media or to their colleagues, friends and family.

Students learn to look at the world with fresh, skeptical eyes. They learn to identify illogical arguments and rhetorical strong-arm tactics. In the Middle Ages, humanities – grammar, logic, rhetoric – prepared you to do science. What Is a Fact? is like that, helping students see how collecting data and being skeptical don't stop once you've left the lab. A questioning, open-minded attitude is an essential life skill.

Timothy Morton, Rita Shea Guffey Chair of English, Rice University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Jingwen Hu, University of Michigan

The future of automobiles is electric, but many people worry about the safety of today's electric vehicles.

Public opinion about EV crash safety often hinges on a few high-profile fire incidents. Those safety concerns are arguably misplaced, and the actual safety of EVs is more nuanced.

I've researched vehicle safety for more than two decades, focusing on the biomechanics of impact injuries in motor vehicle crashes. Here's my take on how well the current crop of EVs protects people:

The burning question

EVs and internal combustion vehicles undergo the same crash-testing procedures to evaluate their crashworthiness and occupant protection. These tests are conducted by the National Highway Safety Administration's New Car Assessment Program and the Insurance Institute for Highway Safety.

These analyses use crash test dummies representing midsize male and small female occupants to evaluate the risk of injuries. The tests can evaluate fire hazard either caused by thermal runaway – when lithium-ion batteries experience rapid uncontrollable heating – in ruptured EV batteries or gas tank leaks of internal combustion vehicles.

None of the Insurance Institute for Highway Safety crash tests of EVs have sparked any fires. New Car Assessment Program crash test reports yield comparable findings. While real-world data analysis on vehicle fires involving EVs is limited, it appears that media and social media scrutiny of EV fire hazard is blown out of proportion.

Weighty matters

What stands out about EV safety is that crash test results, field injury data and injury claims from the Insurance Institute for Highway Safety all reveal that EVs are superior to their internal combustion counterparts in protecting their occupants.

This EV advantage boils down to a blend of physics and cutting-edge technologies.

Thanks to their hefty battery packs positioned at the base of the car, EVs tend to carry considerably more weight and enjoy lower centers of gravity than conventional vehicles. This setup drastically reduces the likelihood of rollover accidents, which have a high rate of fatalities. Moreover, crash dynamics dictate that in a collision between two vehicles, the heavier one holds a distinct advantage because it doesn't slow down as abruptly, a factor strongly linked to occupant injury risks.

On the technology side, most EVs represent newer models equipped with state-of-the-art safety systems, from advanced energy-absorbing materials to cutting-edge crash avoidance systems and upgraded seat-belt and air-bag setups. These features collectively bolster occupant protection.

Where risks do rise

Unfortunately, EVs also present numerous safety challenges.

While the inherent weightiness of EVs offers a natural advantage in protecting occupants, it also means that other vehicles bear the burden of absorbing more crash energy in collisions with heavier EVs. This dilemma is central to the concept of “crash compatibility,” a well-established field of safety research.

Consider a scenario in which a small sedan collides with a heavy truck. The occupants in the sedan always face higher injury risks. Crash compatibility studies measure vehicle “aggressivity” by the level of harm inflicted on other vehicles, and heavier models are almost always deemed more aggressive.

In addition, the increased energy associated with impacts from heavier EVs, particularly electric pickups, poses significant challenges for highway guardrails. Moreover, EVs – especially those operating silently at low speeds – pose increased risks to pedestrians, bicyclists and others who may not hear the EVs approach.

Better technologies, better safety

While EVs offer safety advancements for their own occupants, it's crucial to acknowledge and tackle the safety concerns they pose for others on the road.

I believe that technological advancements will serve as the primary catalyst for overcoming the safety hurdles faced by EVs. Lightweight materials, more powerful sensing technologies and safety algorithms, improved seat belts and better air bags will play pivotal roles in addressing these challenges.

Moreover, the tight connection between EVs and rapidly evolving computing capabilities is likely to foster the development of new safety technologies.

Jingwen Hu, Research Professor of Mechanical Engineering, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.