Study: Neighborhoods aren’t made for childfree people or single parents

Peer-Reviewed Publication

MICHIGAN STATE UNIVERSITY

EAST LANSING, Mich. – Over the last few years, the pandemic has forced most of us to stay home in our own neighborhoods. New research from Michigan State University found that for some groups of people, spending time in their neighborhoods is no block party.

“We found that single parents are much less satisfied with their neighborhoods than married parents, and childfree people who don’t want children aren’t much better off,” said Zachary Neal, associate professor in MSU’s psychology department and co-author of the study.

The study — published in PLOS ONE — is among the first to break down neighborhood satisfaction by specific types of households, including single parents, empty nesters, and childfree adults. The researchers used data from a representative sample of 1,000 adults in Michigan who completed MSU’s State of the State Survey. Although most neighborhood studies compare parents to non-parents, Neal explained that this misses the important differences.

“Married parents were generally very satisfied with their neighborhoods,” said Jennifer Watling Neal, associate professor in the psychology department at MSU and co-author of the study. “People who were planning to have children, or whose children had already moved out were also pretty satisfied. But, neighborhoods don’t seem to be designed with single parents or childfree people in mind.”

Just how much less satisfied are they?

“It’s difficult to put satisfaction into numbers,” Neal said. “But, we collected these data in mid-2020, when COVID was taking off. Single parents and childfree people are as dissatisfied with their neighborhoods as someone who was experiencing a lot of stress around COVID at that time.”

The study was conducted in Michigan, but according to the 2021 census, Michigan is demographically similar to the United States as a whole. Neal also noted that the study included people living in both high- and low-income neighborhoods, and in rural, suburban and urban areas.

Although the study didn’t ask why these groups were less satisfied, Watling Neal offered some possibilities. “Because single parents tend to have less income, they have fewer choices about where to live. Childfree adults may be less satisfied because they feel excluded when parents plan neighborhood social events that are often kid or school-focused.”

With high rates of divorce and falling fertility rates, the researchers said most neighborhoods are home to many single parents and childfree people. They hope this work will highlight the importance of neighborhoods that meet the needs of many different kinds of households.

(Note for media: Please include the following link to the study in all online media coverage https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0273082)

Read on MSU Today

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JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0273082 

SUBJECT OF RESEARCH

People

ARTICLE PUBLICATION DATE

7-Sep-2022

Cigarette smoking more prevalent, harder to quit among rural vs. urban Americans

Peer-Reviewed Publication

INDIANA UNIVERSITY

 

IMAGE: MARIA PARKER. view more 

CREDIT: INDIANA UNIVERSITY

BLOOMINGTON, Ind. -- A new study by Indiana University researchers found that from 2010 to 2020, a larger proportion of rural Americans smoked cigarettes -- and their odds of quitting smoking were lower -- compared to those living in urban areas.

"Cigarette smoking prevalence is higher in rural than urban U.S. communities, and that disparity has only increased over time," said Maria Parker, an assistant professor of epidemiology and biostatistics in the IU School of Public Health-Bloomington. "We wanted to see if quit ratios might account for some of rural vs. urban area smoking disparity, beyond a higher smoking prevalence."

The study team was led by Parker and included colleagues at IU, Rutgers University and Yeshiva University. Their findings were recently published in JAMA Network Open.

Using deidentified data from the U.S. Department of Health and Human Services' 2010-20 National Survey on Drug Use, the researchers analyzed adults who had smoked at least 100 cigarettes in a lifetime, which they defined as lifetime cigarette smoking. Current smoking was defined as smoking one or more cigarettes in the past month, and former smoking as no cigarettes in the past year. Overall and annual quit ratios were estimated as proportions of former smokers among lifetime smokers.

The researchers found that of the 161,348 lifetime cigarette smokers analyzed, 33.5% were former smokers.

In 2020, current smoking prevalence was higher in rural than urban areas -- 19.2% vs 14.4% -- whereas quit ratios were similar in rural and urban areas, at 52.9% and 53.9%, respectively.

However, from 2010 to 2020, the odds of quitting smoking were 75% lower in rural areas compared to urban ones.

Over time, smoking quit ratios among both rural and urban populations increased.

"Our findings support that a persistent rural/urban disparity exists," Parker said. "Not only were smoking prevalence estimates higher in rural areas, but quit ratios were lower in rural areas than urban areas. Rural residents may face more barriers to using smoking cessation services than urban residents, or they may be in an earlier stage of motivation to quit."

Parker said that smoking intervention at the clinical setting, health system or population level might improve reach and sustainability of cessation services for rural residents. She said that leveraging existing smoking quit lines and telehealth solutions may also help rural residents by minimizing barriers to access.

Additional IU authors on the paper include researcher and biostatistician Erik S. Parker and student Emma Eggers, both of the School of Public Health-Bloomington.

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JOURNAL

JAMA Network Open

DOI

10.1001/jamanetworkopen.2022.25326 

ARTICLE TITLE

Trends in Rural and Urban Cigarette Smoking Quit Ratios in the US From 2010 to 2020

Cigarette smoking more prevalent – and harder to quit – among rural vs. urban Americans

Peer-Reviewed Publication

RUTGERS UNIVERSITY

Cigarette smoking is more prevalent among Americans residing in rural areas and they also have a more difficult time quitting smoking than urban residents, according to a study involving Rutgers researchers.

 

The study, published in JAMA Network Open, found smoking prevalence was higher in rural than urban areas – 19.2 percent versus 14.4 percent. While the number of smokers quitting in 2020 was similar in both rural and urban areas – 52.9 percent compared with 53.9 percent – the odds of quitting between 2010 and 2020 were 75 percent lower in rural areas compared with urban areas.

 

“Higher cigarette smoking prevalence and lower cessation in rural populations have led to higher rates of smoking-attributable cancer incidence and death in rural, compared with urban residents,” said Andrea Villanti, coauthor of the study, associate professor in the Department of Health Behavior, Society and Policy at the Rutgers School of Public Health and deputy director of the Rutgers Center for Tobacco Studies. “Tobacco cessation, therefore, is a high-impact target for cancer prevention efforts in rural populations.”

 

The study used data from the U.S. Department of Health and Human Services’ 2010–2020 National Survey on Drug Use to analyze adults who had smoked at least 100 cigarettes in a lifetime, which they defined as lifetime cigarette smoking. Current smoking was defined as smoking one or more cigarettes in the past month and former smoking as no cigarettes in the past year. Overall and annual quit ratios were estimated as proportions of former smokers among lifetime smokers.

 

The researchers found that of the 161,348 lifetime cigarette smokers analyzed, 33.5 percent were former smokers.

 

According to the researchers, the findings support the existence of a persistent rural/urban disparity, possibly attributed to the fact that rural residents may face more barriers to using smoking cessation services than urban residents or may be in an earlier stage of motivation to quit.

 

They suggest smoking intervention at the clinical setting, health system or population level might improve reach and sustainability of cessation services for rural residents. Tobacco cessation resources, including telephone quit lines and telehealth counseling could also reduce barriers to accessing tobacco treatment in rural residents.

 

The study team was led by Indiana University and included researchers at Yeshiva University.

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JOURNAL

JAMA Network Open

DOI

10.1001/jamanetworkopen.2022.25326 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Trends in Rural and Urban Cigarette Smoking Quit Ratios in the US From 2010 to 2020

Adding fungal enzymes to dairy cow rations boosts milk output and quality

Peer-Reviewed Publication

PENN STATE

 

IMAGE: THIS 10-WEEK STUDY INVOLVED 48 HOLSTEIN COWS AT THE PENN STATE DAIRY TEACHING AND RESEARCH CENTER. SOME WERE FED RATIONS SUPPLEMENTED WITH AN ENZYME PREPARATION EXTRACTED FROM A MIXED FUNGAL CULTURE, AND RESEARCHERS THEN EVALUATED THE COWS’ LACTATIONAL PERFORMANCE, METABOLISM AND DIGESTION. view more 

CREDIT: PENN STATE

Supplementing the feed of dairy cattle with enzymes from two funguses simultaneously has a positive effect on the animals’ lactational performance, according to Penn State researchers, who studied the concept in an experiment with cows.

“Exogenous [originating from outside an organism] enzymes have been used widely in human and animal nutrition for decades” said study co-author Alex Hristov, distinguished professor of dairy nutrition. “But recently, lab research has shown that enzymes from Aspergillus oryzae and Aspergillus niger together might have a synergistic effect in the cow’s rumen, promoting the activity of the microbial populations enhancing digestion of fibrous components in the diet.”

For almost 20 years, Hristov’s research group in the College of Agricultural Sciences has studied the effects of feed additives that might improve milk production and cow health and reduce the amount of methane cattle emit as a by-product of the natural digestive process, primarily by belching. Over the years, Hristov’s lab even has evaluated unconventional dietary supplements such as the spicy compound in chili peppers, seaweed and oregano.

This 10-week study, led by Leoni Martins, doctoral degree candidate in animal science, involved 48 Holstein cows at the Penn State Dairy Teaching and Research Center. Some were fed rations supplemented with an enzyme preparation extracted from a mixed culture of Aspergillus. The team then evaluated the cows’ lactational performance, metabolism and digestion.

All procedures involving animals used in this experiment were approved by The Pennsylvania State University's Institutional Animal Care and Use Committee.

The researchers collected milk samples every other week and analyzed milk composition. They collected blood, fecal and urine samples regularly to monitor cow physiological responses to ingesting the enzymes.

The researchers, who recently published their findings in the Journal of Dairy Science, reported that compared with the control group, cows fed the enzymes tended to eat more, and their milk had higher concentrations of protein, lactose and other desirable solids. Overall, enzyme consumption seemed to have a notably positive effect on milk quantity and quality.

“Laboratory studies have suggested we could improve ruminal fermentation and feed digestion with dual enzyme supplementation,” Martins said. “We demonstrated with the cows that enzyme supplementation increased milk production and also resulted in increased solid concentrations in milk.”

The development and adoption of strategies to enhance the performance of dairy cows while reducing feeding costs ultimately is the main goal of dairy nutrition professionals, Hristov noted, and it is critical for feeding a growing world population. Animal scientists have been focusing on cows’ four-chambered stomach — the rumen.

“We are trying to help the rumen microbes do what they do,” he said. “The microbes produce these enzymes that break down fiber, but we are trying to supplement additional enzymes to enhance fermentation in the rumen. There is a very important symbiotic process going on between the microbes and the cow.”

The cow provides the environment and nutrients for the microbes to live and thrive, Hristov explained. And then the microbes provide energy and amino acids for the cow. So, enhancing rumen fermentation with supplements is a way of improving production by the animal.

Most people don’t realize the uniqueness and importance of the rumen, Hristov pointed out — suggesting it is truly one of nature’s wonders.

“The cow is like us — we cannot digest fiber. Without rumen microbes, they couldn’t either,” he said. “We eat cereals and vegetables and so on, but we can barely digest any fiber. And if we digest any fiber, it’s because of the microbes in our guts. Cows and other ruminants digest fiber that very few other animals can digest and convert it into high-quality protein for human consumption.”

Also contributing to the research were J. Oh, Cargill Animal Nutrition, Seongnam, South Korea; M. Harper, CSA Animal Nutrition, Mill Creek, Pennsylvania;  A. Melgar, Agricultural Innovation Institute of Panama, City of Knowledge, Panama; S. E. Räisänen, Department of Agricultural Sciences, University of Helsinki, Finland; X. Chen, Livestock Production Science Branch, Agri-Food Biosciences Institute, Hillsborough, United Kingdom; K. Nedelkov, Trakia University, Stara Zagora, Bulgaria; and T.P. Karnezos, Purina Animal Nutrition, Arden Hills, Minnesota.

The U.S. Department of Agriculture’s National Institute of Food and Agriculture and Purina Animal Nutrition supported this work.

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JOURNAL

Journal of Dairy Science

DOI

10.3168/jds.2022-21990 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Effects of an exogenous enzyme preparation extracted from a mixed culture of Aspergillus spp. on lactational performance, metabolism, and digestibility in primiparous and multiparous cows

Modified microwave oven cooks up next-gen semiconductors

Peer-Reviewed Publication

CORNELL UNIVERSITY

ITHACA, N.Y. – A household microwave oven modified by a Cornell engineering professor is helping to cook up the next generation of cellphones, computers and other electronics after the invention was shown to overcome a major challenge faced by the semiconductor industry.

The research is detailed in a paper published in Applied Physics Letters. The lead author is James Hwang, a research professor in the department of materials science and engineering.

As microchips continue to shrink, silicon must be doped, or mixed, with higher concentrations of phosphorus to produce the desired current. Semiconductor manufacturers are now approaching a critical limit in which heating the highly doped materials using traditional methods no longer produces consistently functional semiconductors.

The Taiwan Semiconductor Manufacturing Company (TSMC) theorized that microwaves could be used to activate the excess dopants, but just like with household microwave ovens that sometimes heat food unevenly, previous microwave annealers produced “standing waves” that prevented consistent dopant activation.

TSMC partnered with Hwang, who modified a microwave oven to selectively control where the standing waves occur. Such precision allows for the proper activation of the dopants without excessive heating or damage of the silicon crystal.

This discovery could be used to produce semiconductor materials and electronics appearing around the year 2025, said Hwang, who has filed two patents for the prototype.

“A few manufacturers are currently producing semiconductor materials that are 3 nanometers,” Hwang said. “This new microwave approach can potentially enable leading manufacturers such as TSMC and Samsung to scale down to just 2 nanometers.”

The breakthrough could change the geometry of transistors used in microchips. For more than 20 years, transistors have been made to stand up like dorsal fins so that more can be packed on each microchip, but manufacturers have recently begun to experiment with a new architecture in which transistors are stacked horizontally. The excessively doped materials enabled by microwave annealing would be key to the new architecture.

For more information, see this Cornell Chronicle story.

-30-

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JOURNAL

Applied Physics Letters

DOI

10.1063/5.0099083 

Violence is common and increasing in pandemic-era California

In a new report, UC San Diego researchers label physical and sexual violence a state ‘epidemic;’ call for health equity-based reform

Reports and Proceedings

UNIVERSITY OF CALIFORNIA - SAN DIEGO

 

IMAGE: THE ANNUAL CALVEX SURVEY MEASURES RATES OF PHYSICAL, SEXUAL AND INTIMATE PARTNER VIOLENCE AMONG CALIFORNIANS. view more 

CREDIT: UC SAN DIEGO HEALTH SCIENCES

Violence is on the rise in California, with significant increases observed during the COVID-19 pandemic, according to the latest annual report from the California Study on Violence Experiences across the Lifespan (CalVEX). Led by researchers at University of California San Diego School of Medicine, CalVEX is the nation’s only multi-year statewide assessment of violent experiences.

The findings, shared in a public report on September 8, 2022, reveal that more than one in six Californians (18 percent) experienced physical or sexual violence in the past year, and one in every 25 Californians experienced intimate partner violence. Rates of both physical and sexual violence have increased since the start of the pandemic, with physical violence nearly doubling for men from 2020 to 2022. Further demographic disparities highlight potential contributing factors that may have been exacerbated by the pandemic. 

“Californians are experiencing violence at epidemic proportions,” said principal investigator Anita Raj, PhD, professor at University of California San Diego School of Medicine and Division of Social Sciences. “Current violence prevention efforts are clearly woefully inadequate and often ignore the gendered nature of violence, its intersections with other socioeconomic vulnerabilities and its disproportionate effects on marginalized populations.” 

The majority of victims never formally report these experiences, so researchers say relying on criminal justice data or health records to examine the state of violence often fails to capture the true breadth of abuses. Instead, CalVEX surveys a representative sample of adults across the state and uses their responses to estimate population rates. Data in the latest report were collected in March 2022 from 2,285 adults.

The results reveal various gender disparities in the experience and perpetration of violence. Men are more likely than women to have faced physical violence, whereas women are more likely than men to have experienced many forms of sexual violence. While more than 1.5 million adults in California admit to committing acts of sexual violence in the past year, men were more than two times as likely as women to report that they perpetrated sexual violence and intimate partner violence. 

Women also showed greater mental health impacts and life disruptions due to violent experiences, with 82 percent of women reporting anxiety or depression as a result of physically aggressive, coercive or forced sexual behavior. Women who reported physical violence were also twice as likely as men to miss work or school as well as change or quit a job. 

Socially and economically vulnerable Californians — including Latino and Black communities, LGBTQ communities, people with a history of homelessness or incarceration, and people living with a disability — also faced disproportionate levels of violence. Experiences of financial distress, including eviction and food or housing insecurity, were associated with a two to eight times increased risk of violence. 

“Our findings suggest the rising rates of violence are linked to the harsher social climate, economic insecurity, and poorer physical and mental health that many Californians have experienced over the last few years due to the pandemic,” said Raj.

The researchers advocate for new policies that strengthen social and economic safety nets, programs in violence prevention, and mental health services across the state. Such a multi-level approach, Raj says, would not only address the current violence crisis, but also support post-pandemic rebuilding and make the state more resilient to other health, environmental and socioeconomic stressors to come.

Co-authors of the report include Nicole E. Johns, Nabamallika Dehingia, Wendy Wei Chang and Jennifer Yore, all at UC San Diego. 

# # #

Electricity-driven water purification method may extend to saltier waters

Grant and Award Announcement

PENN STATE

 

IMAGE: PENN STATE RESEARCHERS WILL FABRICATE MEMBRANES WITH DIFFERENT SURFACE PATTERN GEOMETRIES AND SIZES TO USE IN MEMBRANE CAPACITIVE DEIONIZATION. THE FULL MEMBRANE IS SEEN AT LEFT, AND AT RIGHT, A PORTION OF THE MEMBRANE IS SEEN UNDER AN ELECTRON MICROSCOPE. THE TINY WELLS ALLOW SODIUM AND CHLORIDE IONS BE FILTERED OUT OF UNCLEAN WATER. view more 

CREDIT: ARGES LAB/PENN STATE

While on missions without access to clean water, U. S. Marines face the challenge of procuring and storing enough drinking water to sustain them. Penn State researchers, led by Chris Arges, Penn State associate professor of chemical engineering, are working toward a realistic purification option that is portable, lightweight and easy to operate.

He and co-principal investigator Christopher Gorski, Penn State associate professor of civil and environmental engineering, will use a $570,000, three-year grant from the Office of Naval Research to advance a water purification method, known as membrane capacitive deionization (MCDI). 

“Although the bulk of global desalination utilizes a process known as reverse osmosis at centralized production facilities, it is not suitable for military teams, as it requires high-pressure piping and hardware and is difficult to operate in the field,” Arges said. “MCDI, on the other hand, is effective, mobile and energy efficient.”

Stimulated by battery- or solar-powered electricity, MCDI utilizes ion-exchange membranes and porous electrodes to separate ions, such as sodium and chloride, from water. According to Arges, the method is effective for ground or brackish water but fails to sufficiently purify more highly concentrated water sources, such as seawater. 

“The electricity triggers the sodium ions to migrate across the cation exchange membrane to a negatively charged electrode, while chloride ions migrate across the anion exchange membrane to a positively charged electrode, a process that is known as the principle of electrosorption,” Arges said. “Capturing the ions from the liquid leads to deionized, drinkable water.”

As more and more water is treated in the MCDI unit, the electrodes become saturated with salt, rendering them unable to remove as much salt from the water. At that point, Arges said, the electrodes can be regenerated by slowing down the flow of water and flipping the polarity of the cell. 

“This step in the process wastes some of the water but it also produces electrical energy that can be recovered and applied to the next desalination cycle to lower the overall energy burden,” Arges said. “This allows MDCI to remain energy-efficient.”

To improve MDCI’s effect on more concentrated water sources, Arges and his team will redesign the electrochemical cell module used in MCDI. With tools from the Nanofabrication Lab in the Penn State Materials Research Institute, the researchers will fabricate microscopic wells in an interlocking pattern on the membrane surface. This increases the interfacial area between the membrane and electrodes, improving contact and reducing the distance that sodium and chloride ions need to travel to cross the membrane-electrode interface.  

Additionally, the wells enable the electrode material to store more sodium and chloride ions. This allows users to purify water for longer periods of time before resorting to regeneration. If successful, the improved MCDI unit could purify not just ground and brackish water, but seawater, too, Arges said. 

In previous research, Arges and his team successfully used similar membrane patterning to separate hydronium and hydroxide ions from water in bipolar membranes to make oxygen and hydrogen in an electrolysis cell. 

“Since the proposed approach for this grant has worked for us in the past, we believe the increased interfacial area will reduce ionic transport resistance, leading to cleaner water in greater quantities,” Arges said. 

Density separates the rocky and water-rich exoplanets that orbit red dwarf stars

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

Density measurements of small exoplanets reveal three distinct populations – gassy, rocky and water-rich planets – that can form around a red dwarf star, according to a new study. Small planets are common around red dwarf stars (M dwarfs), and many of those that transect their host star constitute the bulk of known exoplanets ideal for atmospheric characterization via transmission spectroscopy and represent some of the best places to search for signatures of life. However, whether the small worlds surrounding M dwarfs are potentially habitable remains unclear, partly due to our lack of understanding of their composition. Moreover, studying these distant planets from Earth is challenging because of the faint red light their stars emit. In general, the radii of small exoplanets are known to have a bimodal distribution, which has been interpreted as two separate rocky and gassy populations, planets with a thin or thick hydrogen-helium atmosphere, respectively. Using radius and mass measurements from 34 newly detected planets found around closer M dwarf stars from the Transiting Exoplanet Survey Satellite (TESS), Rafael Luque and Enric Pallé show that the planets’ densities provide a cleaner distribution of planet types. Differing from previous understanding, Luque and Pallé discovered that the planets orbiting M dwarfs fall into three different density categories – rocky, gassy and watery exoplanets. According to the findings, the third population matches the density predictions from a planetary model of 50% rock and 50% water. The authors suggest that these water-rich planets likely form with ice and rock far away from the host star before migrating into a closer orbit with the host star. “Although the presence of watery small exoplanets is particularly enticing, all three types of planets around red dwarfs could present potentially habitable conditions for life,” writes Johanna Teske in a related Perspective. “Leaving aside this possibility for discovering alien life-forms, measuring the compositional diversity of planets around red dwarf stars – the most common type of star in the Milky Way – is important for piecing together the complex puzzle of small planets’ formation and evolution.”

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JOURNAL

Science

DOI

10.1126/science.abl7164 

ARTICLE TITLE

Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars

ARTICLE PUBLICATION DATE

9-Sep-2022

Surprise finding suggests ‘water worlds’

are more common than we thought

Analysis finds evidence for many exoplanets made of water and rock around small stars

Peer-Reviewed Publication

UNIVERSITY OF CHICAGO

Water is the one thing all life on Earth needs, and the cycle of rain to river to ocean to rain is an essential part of what keeps our planet’s climate stable and hospitable. When scientists talk about where to search for signs of life throughout the galaxy, planets with water are always at the top of the list.

A new study suggests that many more planets may have large amounts of water than previously thought—as much as half water and half rock. The catch? All that water is probably embedded in the rock, rather than flowing as oceans or rivers on the surface.

“It was a surprise to see evidence for so many water worlds orbiting the most common type of star in the galaxy,” said Rafael Luque, first author on the new paper and a postdoctoral researcher at the University of Chicago. “It has enormous consequences for the search for habitable planets.”

 

Planetary population patterns
Thanks to better telescope instruments, scientists are finding signs of more and more planets in distant solar systems. A larger sample size helps scientists identify demographic patterns—similar to how looking at the population of an entire town can reveal trends that are hard to see at an individual level.

Luque, along with co-author Enric Pallé of the Institute of Astrophysics of the Canary Islands and the University of La Laguna, decided to take a population-level look at a group of planets that are seen around a type of star called an M-dwarf. These stars are the most common stars we see around us in the galaxy, and scientists have catalogued dozens of planets around them so far.

But because stars are so much brighter than their planets, we cannot see the actual planets themselves. Instead, scientists detect faint signs of the planets’ effects on their stars—the shadow created when a planet crosses in front of its star, or the tiny tug on a star’s motion as a planet orbits. That means many questions remain about what these planets actually look like.

“The two different ways to discover planets each give you different information,” said Pallé. By catching the shadow created when a planet crosses in front of its star, scientists can find the diameter of the planet. By measuring the tiny gravitational pull that a planet exerts on a star, scientists can find its mass.

By combining the two measurements, scientists can get a sense of the makeup of the planet. Perhaps it’s a big-but-airy planet made mostly out of gas like Jupiter, or a small, dense, rocky planet like Earth.

These analyses had been done for individual planets, but much more rarely for the entire known population of such planets in the Milky Way galaxy. As the scientists looked at the numbers—43 planets in all—they saw a surprising picture emerging.

The densities of a large percentage of the planets suggested that they were too light for their size to be made up of pure rock. Instead, these planets are probably something like half rock and half water, or another lighter molecule. Imagine the difference between picking up a bowling ball and a soccer ball: they’re roughly the same size, but one is made up of much lighter material.

 

Searching for water worlds
It may be tempting to imagine these planets like something out of Kevin Costner’s Waterworld: entirely covered in deep oceans. However, these planets are so close to their suns that any water on the surface would exist in a supercritical gaseous phase, which would enlarge their radius. “But we don’t see that in the samples,” explained Luque. “That suggests the water is not in the form of surface ocean.”

Instead, the water could exist mixed into the rock or in pockets below the surface. Those conditions would be similar to Jupiter’s moon Europa, which is thought to have liquid water underground.

“I was shocked when I saw this analysis—I and a lot of people in the field assumed these were all dry, rocky planets,” said UChicago exoplanet scientist Jacob Bean, whose group Luque has joined to conduct further analyses.

The finding matches a theory of exoplanet formation that had fallen out of favor in the past few years, which suggested that many planets form farther out in their solar systems and migrate inward over time. Imagine clumps of rock and ice forming together in the cold conditions far from a star, and then being pulled slowly inward by the star’s gravity.

Though the evidence is compelling, Bean said he and the other scientists would still like to see “smoking gun proof” that one of these planets is a water world. That’s something the scientists are hoping to do with JWST, NASA’s newly launched space telescope that is the successor to Hubble.

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JOURNAL

Science

ARTICLE TITLE

Density, not radius, separates rocky and water-rich planets orbiting M dwarf stars

ARTICLE PUBLICATION DATE

8-Sep-2022

A single genomic change enabled increased neurogenesis in modern humans

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

A single amino acid change in the transketolase-like 1 (TKTL1) protein may have given modern humans an advantage over more ancient contemporaries like Neanderthals by enabling increased neocortical neurogenesis, researchers report. According to the authors, this genetic change could contribute to the implied cognitive differences between modern and extinct archaic humans. The outer region of the cerebral cortex – the neocortex – is an evolutionarily advanced brain structure responsible for cognitive abilities. This structure is distinctly large and complex in humans, which is widely thought to endow our species with unique and extraordinary cognitive abilities. However, the evolution of the neocortex in hominins isn’t well understood, and although fossil evidence indicates that the Neanderthal brains were similar in size to those of modern humans, how they might have differed in function or structure remains unknown. Previous studies have shown that differences in neural progenitor cell populations can result in the variable size and shape of neocortices across living species. Anneline Pinson and colleagues compared genomic sequences from modern humans with Neanderthals and other apes and discovered a unique amino acid substitution encoded in the TKTL1 gene of modern humans. When placed in organoids or over-expressed in mouse and ferret brains, Pinson et al. found that the human TKTL1 variant (hTKTL1) drove more generation of basal radial glia (bRG) neuroprogenitors than the archaic variant, which resulted in the proliferation of neocortical neurons. Disrupting hTKTL1 expression or replacing hTKTL1 with the archaic variant in human fetal neocortical tissue and cerebral organoids resulted in reduced bRG and neuron generation. “Together, these observations open the path to discovering more-specific evolutionary changes that shaped the modern human brain and may also help us predict the next steps of its evolution,” write Brigitte Malgrange and Laurent Nguyen in a related Perspective.

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JOURNAL

Science

DOI

10.1126/science.abl6422 

ARTICLE TITLE

Human TKTL1 implies greater neurogenesis in frontal neocortex of modern humans than Neandertals

ARTICLE PUBLICATION DATE

9-Sep-2022

Modern humans generate more brain

neurons than Neandertals

Researchers from Dresden uncover a greater neuron production in the frontal lobe during brain development in modern humans than Neandertals, due to the change of a single amino acid in the protein TKTL1.

Peer-Reviewed Publication

MAX PLANCK INSTITUTE OF MOLECULAR CELL BIOLOGY AND GENETICS (MPI-CBG)

 

IMAGE: MICROSCOPY PICTURE OF A DIVIDING BASAL RADIAL GLIAL CELL, A PROGENITOR CELL TYPE THAT GENERATES NEURONS DURING BRAIN DEVELOPMENT. MODERN HUMAN TKTL1, BUT NOT NEANDERTAL TKTL1, INCREASES BASAL RADIAL GLIA AND NEURON ABUNDANCE. view more 

CREDIT: PINSON ET AL., SCIENCE 2022 / MPI-CBG

The question of what makes modern humans unique has long been a driving force for researchers. Comparisons with our closest relatives, the Neandertals, therefore provide fascinating insights. The increase in brain size, and in neuron production during brain development, are considered to be major factors for the increased cognitive abilities that occurred during human evolution. However, while both Neandertals and modern humans develop brains of similar size, very little is known about whether modern human and Neandertal brains may have differed in terms of their neuron production during development. Researchers from the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) in Dresden now show that the modern human variant of the protein TKTL1, which differs by only a single amino acid from the Neandertal variant, increases one type of brain progenitor cells, called basal radial glia, in the modern human brain. Basal radial glial cells generate the majority of the neurons in the developing neocortex, a part of the brain that is crucial for many cognitive abilities. As TKTL1 activity is particularly high in the frontal lobe of the fetal human brain, the researchers conclude that this single human-specific amino acid substitution in TKTL1 underlies a greater neuron production in the developing frontal lobe of the neocortex in modern humans than Neandertals.

Only a small number of proteins have differences in the sequence of their amino acids – the building blocks of proteins – between modern humans and our extinct relatives, the Neandertals and Denisovans. The biological significance of these differences for the development of the modern human brain is largely unknown. In fact, both, modern humans and Neandertals, feature a brain, and notably a neocortex, of similar size, but whether this similar neocortex size implies a similar number of neurons remains unclear. The latest study of the research group of Wieland Huttner, one of the founding directors of the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) in Dresden, carried out in collaboration with Svante Pääbo, director at the Max Planck Institute for Evolutionary Anthropology in Leipzig, and Pauline Wimberger of the University Hospital Dresden and their colleagues, addresses just this question. The researchers focus on one of these proteins that presents a single amino acid change in essentially all modern humans compared to Neandertals, the protein transketolase-like 1 (TKTL1). Specifically, in modern humans TKTL1 contains an arginine at the sequence position in question, whereas in Neandertal TKTL1 it is the related amino acid lysine. In the fetal human neocortex, TKTL1 is found in neocortical progenitor cells, the cells from which all cortical neurons derive. Notably, the level of TKTL1 is highest in the progenitor cells of the frontal lobe.

Modern human TKTL1, but not Neandertal TKTL1, leads to more neurons in embryonic mouse neocortex
Anneline Pinson, the lead author of the study and researcher in the group of Wieland Huttner, set out to investigate the significance of this one amino acid change for neocortex development. Anneline and her colleagues introduced either the modern human or the Neandertal variant of TKTL1 into the neocortex of mouse embryos. They observed that basal radial glial cells, the type of neocortical progenitors thought to be the driving force for a bigger brain, increased with the modern human variant of TKTL1 but not with the Neandertal variant. As a consequence, the brains of mouse embryos with the modern human TKTL1 contained more neurons.

More neurons in the frontal lobe of modern humans
After this, the researchers explored the relevance of these effects for human brain development. To this end, they replaced the arginine in modern human TKTL1 with the lysine characteristic of Neandertal TKTL1, using human brain organoids – miniature organ-like structures that can be grown from human stem cells in cell culture dishes in the lab and that mimic aspects of early human brain development. “We found that with the Neandertal-type of amino acid in TKTL1, fewer basal radial glial cells were produced than with the modern human-type and, as a consequence, also fewer neurons,” says Anneline Pinson. “This shows us that even though we do not know how many neurons the Neandertal brain had, we can assume that modern humans have more neurons in the frontal lobe of the brain, where TKTL1 activity is highest, than Neandertals." The researchers also found that modern human TKTL1 acts through changes in metabolism, specifically a stimulation of the pentose phosphate pathway followed by increased fatty acid synthesis. In this way, modern human TKTL1 is thought to increase the synthesis of certain membrane lipids needed to generate the long process of basal radial glial cells that stimulates their proliferation and, therefore, to increase neuron production.

“This study implies that the production of neurons in the neocortex during fetal development is greater in modern humans than it was in Neandertals, in particular in the frontal lobe,” summarizes Wieland Huttner, who supervised the study. "It is tempting to speculate that this promoted modern human cognitive abilities associated with the frontal lobe."

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JOURNAL

Science

DOI

10.1126/science.abl6422 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Human TKTL1 implies greater neurogenesis in frontal neocortex of modern humans than Neandertals