Monday, June 30, 2025

 


The bold place bets on the VIX



For investors who can stomach the risk, Wall Street’s ‘fear index’ leads to potential gains




University of Texas at Austin





Since Wall Street’s “fear index” spiked in April, even casual investors have watched it nervously for signs of whether to buy, hold,, or run for their lives.

The CBOE Volatility Index, commonly known as the VIX, signals the market’s expectations for volatility over the coming 30 days. When the VIX rises, investors expect steeper ups and downs. When it falls, it suggests calmer conditions.

In early April, the VIX did both. It hit 60 — for the first time since the COVID-19 pandemic — after President Donald Trump announced worldwide tariffs. After most tariffs were paused, the index slid to 17 by mid-June.

In new research, Ehud Ronn, professor of finance at Texas McCombs, tests a long-held belief about the VIX: that volatility can be profitable. Over time, the theory goes, the market tends to reward higher levels of systemic risk with higher returns.

Ronn finds that it does, but with some caveats. He offers fresh insights into how the index might factor into investment decisions.

With Liying Xu of Oklahoma Baptist University, Ronn compared VIX levels with subsequent realized returns for the S&P 500. They measured indicators on a daily, weekly, and monthly basis over periods of two, four, five, and 10 years from 2012 to 2022. They found that generally, the higher the VIX, the more robust the ultimate returns.

“We were able to show that subsequent returns were indeed higher,” says Ronn. “In other words, if you have the financial and intestinal fortitude to step up to the plate when everyone else is headed out the door, on average you will be rewarded for taking on that risk.”

Hold, Don’t Sell

The researchers also evaluated a contrary approach proposed by another researcher: lowering equity exposure in times of higher volatility. He proposed that when the VIX rises above 30%, an investor should reduce the percentage of stocks in their portfolios. They should buy back in once volatility dies down.

Ronn and Xu simulated that strategy for 29 historical episodes in which the VIX exceeded 30%. They found that the portfolio underperformed the market. Says Ronn, “The proposed solution is not something that investors should follow.”

Instead, he says, the average investor does better to stand pat when stocks fall and the VIX climbs. In his simulation, holding stocks through episodes of high volatility produced a 10.9% higher annualized return than selling and buying back.

“Decide on the fraction of stocks, bonds, and cash you’re comfortable holding, and then don’t respond to every little twitch in the market,” he says.

He has different advice for one group of investors: those with high appetites for risk. “When the VIX is high, invest, because on average you will be compensated,” Ronn says.

“But that really does take guts, because you just don’t know beforehand when the VIX will peak and the market will trough. If I knew that, I’d be retired in the Riviera right now.”

Is VIX a Contrarian Indicator? On the Positivity of the Conditional Sharpe Ratio” is published inEconometrics.

 

 

Researchers say belief that lefties are more creative doesn’t add up


HANDEDNESS NOT POLITICS



Cornell University





ITHACA, N.Y. – Scouring more than a century of studies that explored links between handedness and creativity, new Cornell University research finds the widespread belief that lefties are more creative is not actually true.

“The data do not support any advantage in creative thinking for lefties,” said Daniel Casasanto, associate professor of psychology. “In fact, there is some evidence that righties are more creative in some laboratory tests, and strong evidence that righties are overrepresented in professions that require the greatest creativity.”

Casasanto is the senior author of “Handedness and Creativity: Facts and Fictions,” published in the Psychonomic Bulletin and Review.

Casasanto said there are scientific reasons to believe that left-handed people, conservatively estimated to comprise about 10% of the population, would have an edge in creativity. Divergent thinking – the ability to explore many possible solutions to a problem in a short time and make unexpected connections – is supported more by the brain’s right hemisphere.

The researchers conducted a meta-analysis – sorting through nearly 1,000 relevant scientific papers published since 1900. Most were weeded out because they did not report data in a standardized way or included only righties (the norm in studies seeking homogeneous samples), leaving 17 studies reporting nearly 50 effect sizes.

The meta-analysis revealed that handedness made little difference in the three most common laboratory tests of its link to divergent thinking; if anything, righties had a small advantage on some tests.

“If you look at the literature on the whole,” Casasanto said, “this claim of left-handed creativity is simply not supported.”

What has sustained belief in left-handers’ special creativity? One factor, the authors speculate, is left-handed exceptionalism: the idea that it’s rare to be a lefty and rare to be a creative genius, so perhaps one explains the other. Another is the popular perception that creative genius is linked to mental illness. It turns out lefties, who are more likely to be artists, experience higher rates of depression and schizophrenia.

“This idea that left-handedness, art and mental illness go together – what we call the ‘myth of the tortured artist’ – could contribute to the appeal and the staying power of the lefty creativity myth,” Casasanto said.

Finally, Casasanto said, the urban legend is a case study in statistical cherry picking – frequent citing over the years of a small number of studies with small or biased samples.

“The focus on these two creative professions where lefties are overrepresented, art and music, is a really common and tempting statistical error that humans make all the time,” Casasanto said. “People generalized that there all these left-handed artists and musicians, so lefties must be more creative. But if you do an unbiased survey of lots of professions, then this apparent lefty superiority disappears.”

For additional information, see this Cornell Chronicle story.

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Where there’s fire, there’s smoke



New app estimates health impacts of breathing smoke from wildfires



Harvard John A. Paulson School of Engineering and Applied Sciences

SMRT-flames 

image: 

Schematic workflow for generating smoke risk index. The index is a metric that highlights those grid cells where potential wildfires would pose the greatest population-weighted smoke exposure downwind. 

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Credit: Mickley Lab / Harvard SEAS




Earlier this year, wildfires in southern California killed 30 people, destroyed more than 18,000 homes and burned more than 57,000 acres. The fires were a stark reminders of the threat of worsening climate change, and the increased likelihood of future devastating fires. With these fires comes smoke, which has long-term health effects for the people exposed to it – whether they are close to the source, or many miles away.  

A Harvard atmospheric modeling team has created an online platform that could help communities identify areas in need of controlled burns or other fire management strategies, with the goal of preventing future uncontrolled fires and, more specifically, reducing smoke exposures.

The research is published in Environmental Science & Technology and is led by Loretta Mickley, senior research fellow in chemistry-climate interactions at the John A. Paulson School of Engineering and Applied Sciences (SEAS) and leader of the Atmospheric Chemistry Modeling Group. Two alumni from Mickley’s group co-led the effort: Tianjia (Tina) Liu, now an assistant professor at University of British Columbia, and Makoto Kelp, now a postdoctoral fellow at Stanford University.   

“We want to know not just where catastrophic fires are likely to occur, but which fires will generate the most smoke, and affect the most people downwind,” Mickley said. This is important given the large numbers of people who die prematurely from breathing wildfire smoke, particularly in the West, Mickley continued, even as decades of progress have been made in reducing urban air pollution on the coasts.

Targeted land management can reduce smoke exposures

Focusing on the wildfire-prone Northern California region, the researchers estimated that in 2020, targeted land management in the 15 highest-risk areas (about 3.5% of the region) could have reduced total smoke exposures by as much as 18%. They also estimated that, following the 2020 western fire season, 36,400 people died from complications associated with breathing the very fine particles found in smoke. These particles, known as “PM 2.5,” have diameters of less than 2.5 microns and are a potentially toxic form of air pollution that disproportionately impacts vulnerable people, including those with asthma, heart conditions, and the elderly.

The researchers’ new user-friendly application, SMRT-Flames, allows fire managers and policymakers to assess potential wildfire-related smoke exposure across regions and to target land management practices accordingly. Most wildfire tools attempt to predict fire risk, but SMRT-Flames also explicitly considers smoke exposure across populations. The app currently focuses on wildfire management in Northern California, but it can be expanded to other areas. 

“With our methodology, you can consider hypothetical scenarios and plan prescribed fires to reduce smoke exposure over an entire region, not just the immediate area where that prescribed fire is happening,” Liu said.  

The research leverages a Harvard-developed computer model called GEOS-Chem. The model combines meteorological, chemical, and geophysical data to predict how fires would behave across various regions and how smoke would pool and disperse.

Prescribed burns are efficacious

SMRT-Flames underscores the efficacy of prescribed burning, a land management strategy that involves intentionally setting smaller fires to prevent larger, catastrophic events in the future. Prescribed burning has not been widely practiced in the West, but a growing body of research points to the benefits of controlled burns for culling accumulated underbrush.

“This idea of wildfires being out of control is due to a combination of factors, including climate, but also this legacy of fire suppression where we’ve actively prevented fires for the last 100 years, which has led to this huge buildup of fuels,” explained Kelp.

Previous research by the team found that controlled burns in key zones in northern California, western Oregon, and eastern Washington could have an outsized effect on reducing wildfire smoke exposure throughout the entire western U.S.

The new research paper required methodological innovations and decisions about what factors should account for smoke risk, which is difficult to estimate due to confounding factors like meteorological conditions and differing landscapes. “We had decisions to make during the research process for integrating the knowledge of wildfires from various disciplines, from an atmospheric perspective as well as from a land cover perspective,” explained first author and undergraduate research assistant Karina Chung.

Among the team’s most surprising insights was showing that people who live at the borders between urban and rural areas, known as the wildland-urban interface, are especially vulnerable to smoke exposure. “That really popped out of our results,” said Mickley. “This finding underscores the need to really think about fuel treatments close to or in those areas. We hope that our results provide some justification for considering prescribed fires as a prevention strategy, even close to where people live.”

The paper was co-authored by Karn Vohra, Dana Skelly, Matthew Carroll, and Joel Schwartz. It was supported by the NOAA Climate Program Office’s Modeling, Analysis, Predictions, and Projections Program under Grant No. NA22OAR4310140 and also by NOAA Climate and Global Change Postdoctoral Fellowships to Liu and Kelp.


Intent to test for COVID-19 in the US post pandemic era



JAMA Network Open






About The Study: 

Nearly one-third of U.S. adults would not or might not test for suspected COVID-19, largely because they do not see value in testing, according to the results of an online national survey. Test hesitancy may delay oral antiviral initiation and could result in missed opportunities to limit transmission. Efforts are needed to increase awareness of the value of testing. 



Corresponding Author: To contact the corresponding author, Kimberly A. Fisher, MD, email kimberly.fisher2@umassmed.edu.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2025.18250)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

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Embed this link to provide your readers free access to the full-text article 

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About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication. 

 

Smallmouth bass evolve to resist removal in the Adirondacks




Cornell University





ITHACA, N.Y. - Decades of efforts to eradicate invasive smallmouth bass from a midsized Adirondack lake have led to a surprising result: The bass rapidly evolved to grow faster and invest more in early reproduction, leading to an even larger population of smaller fish.

A study published in the journal Proceedings of the National Academy of Sciences revealed that, in response to pressures from annual removal of a quarter of the smallmouth bass population, the numbers of small bass – 5 inches and under – have increased even as larger fish (greater than 12 inches) were mostly eliminated.

Though smallmouth bass are native to North America, they were introduced widely across the Adirondacks in the 1900s, where they took over many lakes. Their arrival led to declines of native fish species and stunting of growth rates in prized brook and lake trout, which compete with bass for the same prey.

The findings have important implications from a management standpoint, both in terms of highlighting the importance of preventing non-native species invasions before they happen and in understanding that efforts to suppress a species may in fact backfire, leading to the opposite effect. 

While plant and insect populations have long been recognized to evolve in response to herbicide or pesticide applications, manual removals of plants and animals were not thought to induce such adaptations. However, the bass population shifted towards a fast-living and early-maturing life history strategy as a result of drastically heightened mortality rates. One solution may be to conduct removals less often or take only a subset of fish, which could reduce the evolutionary pressure for bass to adapt, but the authors said that more study is needed. The broad takeaway for other invasive species removal efforts is that, even in the absence of a clear evolutionary pathway, eradication efforts should be seen as an evolutionary arms race.

“Twenty-five years ago, Cornell’s Adirondack Fishery Research Program set out to test whether we could functionally eradicate smallmouth bass from a lake,” said Peter McIntyre, professor in the departments of Natural Resources and Ecology and Evolutionary Biology, and among the senior authors of the study. “It took us 25 years to prove why the answer is no: the fish evolved to outmaneuver us.”

“What we’ve documented is that life history traits like growth rate and age at maturity are things that can evolve to reduce the susceptibility to our removal efforts,” said first author Liam Zarri, who led the study and is now a postdoctoral fellow at Smithsonian’s National Zoo in Washington, D.C.

Natural resources professor and study co-author Cliff Kraft began efforts in 2000 to suppress bass in Little Moose Lake in the Adirondacks with boat electrofishing, which uses a generator to electrify water and temporarily stun fish. Scientists then scooped them up, released the native species back into the lake, and removed all captured bass.

“The expectation was that if you removed thousands of bass from the lake every year, it would cause a rapid population crash leading to eradication” Zarri said. “For the first year or two, that seemed to be the case.”

At the same time, he said, population sizes of native fishes started recovering. Also, lake trout growth rates began to increase. 

But after a few years, the researchers noticed their catch rates were increasing, rather than decreasing, driven by an expanding population of young bass.

Zarri’s genetic analysis, made possible by smallmouth bass tissue samples that Kraft collected starting in 1995, revealed that selection pressures from removing fish resulted in dramatic genetic changes between 2000 and 2019 in genes across three chromosomes. These genomic regions were associated with increased growth and early maturation rates. 

Two companion papers, led by Tommy Detmer, a former aquatic ecologist at Cornell who is now an assistant professor at Iowa State University, examined the effects of smallmouth bass removal efforts on native fishes and on smallmouth bass behavior.

In one paper, co-led by Montana Airey, a doctoral candidate in McIntyre’s lab, the team found that nearly all native freshwater fish populations initially rebounded. But ongoing monitoring revealed that after 10 years, some fish populations continued to respond positively while others reverted back to the same low abundance as when smallmouth bass dominated the lake. The results highlight the importance of continual monitoring to understand the full ecosystem dynamics over time, Zarri said.

The findings have important implications for brook and lake trout in the Adirondacks. Not only are they threatened by warming surface waters and depleted oxygen levels in cooler deeper water where the fish retreat to over summers, they now also face the added burden of competing with bass for prey, McIntyre said.

Detmer’s other paper found that smallmouth bass, but not other native fish, in Little Moose Lake became more skittish in the years after removal efforts began. One possible explanation is that growing up in a lake where bass are removed four times per year has made the survivors cautious.

“We are also interested in testing whether there is a genetic underpinning for behavior,” whereby fish that are more skittish by nature (rather than by nurture) have avoided being caught, resulting in the skittish genotype sweeping through the population, Zarri said.  

“Long-term studies of management efforts are critical, not only for deepening our understanding of natural ecosystems, but also for evaluating the effectiveness of specific management tools,” Detmer said.

Zarri, McIntyre and Kraft are co-authors on the companion studies. 

Project funding was in part provided by the Adirondack League Club, the Northeast Climate Adaptation Science Center, the National Science Foundation Extreme Science and Engineering Discovery Environment, the Cornell University Elizabeth Miller Francis ‘47 Summer Research Grant, and the Cornell University Kieckhefer Adirondack Fellowship.

-30-

 

Four-day school week may not be best for students, review finds



A new UO research review finds little evidence that the four-day school week benefits students



University of Oregon





A new University of Oregon review of 11 studies found little evidence that the four-day school week benefits student academic performance, attendance, behavior or graduation rates.

The HEDCO Institute for Evidence-Based Educational Practice at the UO conducted the systematic review, a rigorous analysis of the highest-quality research available on the four-day school week in the United States.

“Districts often turn to four-day school weeks to address budget and staffing pressures, but the evidence suggests this change may come at a cost to students,” said Elizabeth Day, a research assistant professor at the HEDCO Institute and part of the team that produced the report. “There’s no consistent evidence that moving to a four-day schedule improves learning outcomes — and in some cases, it may do the opposite.”

The four-day school week schedule is a growing trend in U.S. education, with adoption by 2,100 schools in more than 850 school districts. The schedule is more common in rural areas, but an increasing number of suburban and urban districts are considering it.

The HEDCO Institute review findings paint a complex picture, one that differs based on school location (rural vs. non-rural), grade level and student outcome.  

Key Findings: 

No statistically large positive effects were found for any student outcome in the highest-quality studies.

Rural districts have been studied more rigorously than non-rural districts and no studies included just city schools.

In rural districts, evidence was mixed and suggested a four-day school week:

  • Decreases math and reading achievement for K-8 students  
  • Increases math scores, increases on-time and 5-year graduation rates for high-school students 
  • Decreases on-time progression, and increases chronic absences for high school students 

In non-rural districts:

  • Little to no effect on K-8 student achievement 
  • Decreases math scores, decreases on-time and 5-year graduation rates, and increases absences for high school students 

 

For studies combining rural and non-rural districts, most findings were negative:  

  • Decreases math and reading achievement, increases absences and chronic absences, and decreases 5-year graduation rates across grades K-12

The HEDCO Institute review highlighted two critical unanswered questions: 

How much instructional time is lost or preserved?

Maintaining instructional hours is important for minimizing negative impacts on student achievement. Loss of learning time risks a loss of learning.

What do students do on the fifth day?

Without school, home or community-supported programs, students may lack access to safe, age-appropriate activities — putting their development and well-being at risk. Maintaining activities that foster healthy youth development on the fifth day is important for minimizing other negative impacts. 

 The review focused exclusively on student outcomes, including:  

  • Academic achievement: math and reading test scores, proficiency and gains 
  • Academic attainment: graduation rates, dropout rates and on-time progression 
  • Attendance: average daily attendance, fraction of students absent, chronic absenteeism
  • Criminal activity: frequency of crime at school and of crime not at school, property crime, violent crime and drug violations
  • Disciplinary incidents: days missed for discipline, and frequency of substance use, vandalism, bullying, fighting, weapons, truancy, and school bus disciplinary instances 

— By Joe Golfen, HEDCO Institute for Evidence-Based Educational Practice, College of Education, University of Oregon 

About the HEDCO Institute for Evidence-Based Educational Practice at the University of Oregon
Part of the University of Oregon’s College of Education, the HEDCO Institute conducts rigorous syntheses of education research to inform real-world decision-making. This systematic review is part of the Institute’s mission to connect policymakers and practitioners with trustworthy evidence. 

 

THC undetectable after withdrawal period in cows fed hemp byproduct



Oregon State University





CORVALLIS, Ore. – A new study examined feeding a hemp byproduct to cows and found that the trace amounts of psychoactive THC in hemp were undetectable in the milk and edible tissue of cows if they were weaned off the byproduct before milking or processing.

The findings are significant because the hemp byproducts, known as spent hemp biomass, currently have little to no economic value for hemp producers. Spent hemp biomass has not been legalized as feed for livestock by the Food and Drug Administration due to the potential presence of THC and its potential impacts on animal health.

“This study is one step forward in providing the data needed for FDA approval of spent hemp biomass as a feed supplement for livestock,” said Massimo Bionaz, lead author of the study and an associate professor in the Department of Animal and Rangeland Sciences at Oregon State University.

The legalization of hemp as an agricultural crop in 2018 in the United States and in other countries around the world at the same time resulted in a significant increase in global cultivation.

In the United States, more than 60% of hemp is grown to extract cannabidiol (CBD), while it is grown primarily for seed or hemp oil in Europe and Canada. The CBD extraction process creates a large amount of plant-matter byproduct, referred to as spent hemp biomass.

Past studies by Bionaz and others have found that spent hemp biomass, hemp seed and hempseed meal are suitable and safe feed ingredients for livestock animals, including cattle, lambs and chickens.

For the new study, which was recently published in the Journal of Agricultural and Food Chemistry, the researchers had two objectives:

  • Determine the accumulation, absorption and clearance of cannabinoids, including CBD, in milk and tissues of dairy cows fed spent hemp biomass.
  • Assess the risks for people when consuming milk from those cows.

The project involved 18 Jersey cows. For 28 days, nine were fed the experimental diet with 13% spent hemp biomass, and nine received the control diet, with 13% alfalfa pellet instead of the spent hemp biomass. The cows then went through a four-week withdrawal period in which they all received the control diet.

The researchers found that dairy cows absorb significant amounts of cannabinoids after eating spent hemp biomass. However, cannabinoids disappear from the system, including the milk, within 15 days.

“Two weeks of spent hemp biomass withdrawal from diet of the cows eliminates any risk of ingesting THC by consuming the milk from those cows,” Bionaz said.

Co-authors of the paper are Agung Irawan, Daniel Nosal, Ruth N. Muchiri, Richard van Breemen, Serkan Ates, Jenifer Cruickshank, Juliana Ranches, Charles Estill and Alyssa Thibodeau, all of Oregon State. Oregon State is also home to the Global Hemp Innovation Center.