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New study solves mystery of how soft liquid droplets erode hard surfaces

A first-of-its-kind study led by University of Minnesota Twin Cities researchers reveals why liquid droplets have the ability to erode hard surfaces. The…

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A first-of-its-kind study led by University of Minnesota Twin Cities researchers reveals why liquid droplets have the ability to erode hard surfaces. The discovery could help engineers design better, more erosion-resistant materials.

Credit: Cheng Research Group, University of Minnesota

A first-of-its-kind study led by University of Minnesota Twin Cities researchers reveals why liquid droplets have the ability to erode hard surfaces. The discovery could help engineers design better, more erosion-resistant materials.

Using a newly developed technique, the researchers were able to measure hidden quantities such as the shear stress and pressure created by the impact of liquid droplets on surfaces, a phenomenon that has only ever been studied visually. 

The paper is published in Nature Communications, a peer-reviewed, open access, scientific journal published by Nature Research.

Researchers have been studying the impact of droplets for years, from the way raindrops hit the ground to the transmission of pathogens such as COVID-19 in aerosols. It’s common knowledge that slow-dripping water droplets can erode surfaces over time. But why can something seemingly soft and fluid make such a huge impact on hard surfaces?

“There are similar sayings in both eastern and western cultures that ‘Dripping water hollows out stone,’” explained Xiang Cheng, senior author on the paper and an associate professor in the University of Minnesota Department of Chemical Engineering and Materials Science. “Such sayings intend to teach a moral lesson: ‘Be persistent. Even if you’re weak, when you keep doing something continuously, you will make an impact.’ But, when you have something so soft like droplets hitting something so hard like rocks, you can’t help wondering, ‘Why does the drop impact cause any damage at all?’ That question is what motivated our research.”

In the past, droplet impact has only been analyzed visually using high-speed cameras. The University of Minnesota researchers’ new technique, called high-speed stress microscopy, provides a more quantitative way to study this phenomenon by directly measuring the force, stress, and pressure underneath liquid drops as they hit surfaces.

The researchers found that the force exerted by a droplet actually spreads out with the impacting drop—instead of being concentrated in the center of the droplet—and the speed at which the droplet spreads out exceeds the speed of sound at short times, creating a shock wave across the surface. Each droplet behaves like a small bomb, releasing its impact energy explosively and giving it the force necessary to erode surfaces over time.

Besides paving a new way to study droplet impact, this research could help engineers design more erosion-resistant surfaces for applications that must weather the outdoor elements. Cheng and his lab at the University of Minnesota Twin Cities already plan to expand this research to study how different textures and materials change the amount of force created by liquid droplets.

“For example, we paint the surface of a building or coat wind turbine blades to protect the surfaces,” Cheng said. “But over time, rain droplets could still cause damage via impact. So, our research after this paper is to see if we can reduce the amount of shear stress of droplets, which would allow us to design special surfaces that can mitigate the stress.”

In addition to Cheng, the research team included University of Minnesota chemical engineering Ph.D. student Ting-Pi Sun, University of Santiago, Chile Assistant Professor Leonardo Gordillo and undergraduate students Franco Álvarez-Novoa and Klebbert Andrade, and O’Higgins University, Chile Assistant Professor Pablo Gutiérrez.

The research was funded by the National Science Foundation.

Watch a video demonstrating in slow motion how a water droplet impacts a sandy surface.


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Why Is The VIX So Low? A Surprising Answer Emerges In The Market’s Microstructure

Why Is The VIX So Low? A Surprising Answer Emerges In The Market’s Microstructure

One of the most frequent questions tossed around Wall Street…

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Why Is The VIX So Low? A Surprising Answer Emerges In The Market's Microstructure

One of the most frequent questions tossed around Wall Street trading desks (and strip clubs), and which was duly covered by Bloomberg recently in "Fear Has Gone Missing in Wall Street’s Slow-Motion Bear Market", is why despite the crushing bear market and the coming recession, does the VIX refuse to rise sustainably above 30, or in other words, why is the VIX so low?

As Goldman's Rocky Fishman wrote in a recent note "Option Markets Take the SPX Bear Market in Stride" (available to professional subs), "one of the most popular questions we have received is why the VIX hasn't surpassed its March peak (36) despite the SPX being lower than it was in March and realized vol being higher than it was in March."

Here, Fishman notes that implied volatility was unusually high in March, and the current VIX level (29) is only slightly low for the current level of realized vol. Furthermore, a VIX around 30 typically happens with the 5Y CDX HY spread above 600, and although it has risen steadily it's currently in the mid 500's.

Meanwhile, even as the VIX has fallen moderately since late April, both vol risk premium and skew have both fallen dramatically.

Picking up on this quandary, overnight JMorgan also joined the discussion with its analyst Peng Cheng laying out his own thoughts on why the VIX remains so low (note is also available to professional subs), and similar to Goldman notes that the current bear market, despite being deeper in magnitude, has produced VIX levels well below the peak observed during previous market sell-offs:

However, unlike Goldman which mostly analyzes the VIX in the context of a macro framework, JPM's Cheng offers observations based on his analysis of market microstructure in both equity and options markets.

Cheng starts with the previously noted low realized volatility: as the JPM strategist writes, YTD, the SPX realized vol, measured on a close to close basis, is only 25.5, which means that delta-hedged put options would have lost money in the gamma component. From a technical perspective, JPM believes that return volatility is dampened by a lack of intraday price momentum and increasingly frequent occurrences of intraday price reversal. As seen in the next chart, intraday reversal has only started to become noticeable in the last two years. Prior to that, intraday momentum was the dominant market behavior.

This diminishing intraday price momentum has had a non-trivial impact on realized volatility, according to JPM which estimates that if the intraday return correlation remained the same as pre-pandemic, YTD volatility would be close to 28.8, or 3.3 vol points higher than realized.

As an aside, those asking for the reason behind this change in intraday patterns in the last couple of years, Cheng notes that "this is a complex topic" but in short, his view is that it is a result of 1) crowding in intraday momentum trading strategies and 2) a potential shift in option gamma dynamics as discussed below.

Supply/demand of S&P 500 options: Although the estimation of market level option gamma profile is highly dependent on many factors, including assumptions on open interest, OTC options, and leveraged ETFs, etc., in a report published earlier this year, JPM's quants presented a more dynamic estimation of the gamma profile by using tick level data. Specifically, they assigned directions to SPX and SPY option trades based on their distance to the best bid/offer at the tick level, rather than the constant assumption of investors being outright long puts and short calls. The updated results are shown below.

Tha chart shows that starting in 2020, the put gamma imbalance has fallen meaningfully. This is the result of investors’ changing preference from buying outright puts to put spreads for protection, in JPM's view. And year to date, the decline in gamma demand has not improved. Moreover, and echoing what we have said on several recent occasions, JPM notes that judging from the outright negative put gamma imbalance in early 2022, it appears that investors have been monetizing hedges that had been held since 2021 - note the consistently positive and relatively elevated put gamma imbalance throughout 2021, which suggests that protections were put on during this period.

More in the full note available to pro subs

Tyler Durden Wed, 06/29/2022 - 15:05

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Dr. Stephen Kingsmore receives prestigious Precision Medicine World Conference 2022 Luminary Award

SAN DIEGO, Calif. – June 29, 2022 – Rady Children’s Institute for Genomic Medicine® (RCIGM) today announced that Stephen Kingsmore, MD, DSc, President…

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SAN DIEGO, Calif. – June 29, 2022 – Rady Children’s Institute for Genomic Medicine® (RCIGM) today announced that Stephen Kingsmore, MD, DSc, President and CEO, was presented with the Precision Medicine World Conference (PMWC) 2022 Luminary Award at this year’s conference in the Silicon Valley region of California for his innovation in rapid neonatal molecular diagnoses using whole-genome sequencing.

Credit: Rady Children’s Institute for Genomic Medicine

SAN DIEGO, Calif. – June 29, 2022 – Rady Children’s Institute for Genomic Medicine® (RCIGM) today announced that Stephen Kingsmore, MD, DSc, President and CEO, was presented with the Precision Medicine World Conference (PMWC) 2022 Luminary Award at this year’s conference in the Silicon Valley region of California for his innovation in rapid neonatal molecular diagnoses using whole-genome sequencing.

The Luminary Award recognizes the recent contributions of prominent figures who have accelerated precision medicine into the clinic. Additional PMWC 2022 honorees included Dr. Albert Bourla, Pfizer, for his extraordinary achievement in leading the record-time development of a vaccine and antiviral drug against the coronavirus and Dr. Stephen Hoge, Moderna, for overseeing R&D of the first antiviral synthetic mRNA vaccines ever created, including the one against COVID-19.

“I am honored to receive this award and be among this extraordinary group of past and present recipients focused on the clinical adoption of precision medicine,” said Dr. Kingsmore. “At RCIGM, we are transforming pediatric healthcare through the power of Rapid Precision Medicine™ by offering the fastest delivery of rapid Whole Genome Sequencing™ to enable prompt diagnosis and targeted treatment of critically ill newborns and children in intensive care. We know that time matters – a fast, molecular diagnosis can make the difference between improved outcomes and a lifetime of disability, or even life itself.”

Dr. Kingsmore leads a multi-disciplinary team of scientists, physicians, genetic counselors, software engineers and bioinformaticians who are pioneering the use of rWGS® to enable precise diagnoses for critically ill newborns. In 2021, he led the RCIGM team to set a new record of 13.5 hours for achieving the fastest molecular diagnosis using rWGS, breaking his previous 2018 world record of 19.5 hours. 

PMWC is the largest and original annual conference dedicated to precision medicine. PMWC’s mission is to bring together recognized leaders, top global researchers and medical professionals, and innovators across healthcare and biotechnology sectors to showcase practical content that helps close the knowledge gap between different sectors, thereby catalyzing cross-functional fertilization and collaboration in an effort to accelerate the development and spread of precision medicine.

Rady Children’s Institute for Genomic Medicine

Rady Children’s Institute for Genomic Medicine is transforming neonatal and pediatric health care by harnessing the power of Rapid Precision Medicine™ to improve the lives of children and families facing rare genetic disease. Founded by Rady Children’s Hospital and Health Center, the Institute offers the fastest delivery of rapid Whole Genome Sequencing™ to enable prompt diagnosis and targeted treatment of critically ill newborns and children in intensive care. The Institute now provides clinical genomic diagnostic services for a growing network of more than 70 children’s hospitals. The vision is for this life-changing technology to become standard of care and enable clinicians nationwide to provide rapid, personalized care. Learn more about the non-profit Institute at RadyGenomics.org. Follow us on Twitter and LinkedIn.

Media Contact:

Ben Metcalf
bmetcalf@rchsd.org
+1 (619) 822-8593
 


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Fauci Suffers “Much Worse” COVID Symptoms After ‘Paxlovid Rebound’

Fauci Suffers "Much Worse" COVID Symptoms After ‘Paxlovid Rebound’

Fully-vaxx’d and double-boosted mask-admirer Anthony Fauci is suffering.

Two…

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Fauci Suffers "Much Worse" COVID Symptoms After 'Paxlovid Rebound'

Fully-vaxx'd and double-boosted mask-admirer Anthony Fauci is suffering.

Two weeks ago, we reported that President Biden's chief medical adviser had COVID.

The 81-year-old reportedly had 'mild symptoms' and of course he 'said the words'...

Of course, Fauci followed the CDC guidelines and ingested the government-blessed treatment - Paxlovid - due to his age and possible risks from the virus.

So, that should have been it right?

But no. During an event at Foreign Policy’s Global Health Forum, Fauci admitted he had not had a good experience:

“After I finished the five days of Paxlovid, I reverted to negative on an antigen test for three days in a row,” Fauci said Tuesday .

“And then on the fourth day, just to be absolutely certain, I tested myself again. I reverted back to positive.”

Interestingly, Fauci admitted:

"...this is becoming more and more typical based on more clinical studies..."

As Bloomberg reports, large numbers of patients have reported the phenomenon, often called Covid rebound or Paxlovid rebound, of returning symptoms after taking a full course of Pfizer’s drug.

While Pfizer Chief Executive Officer Albert Bourlasaid in May that doctors could prescribe a second course of treatment to such patients, US drug regulators have said there’s no evidence that a repeat will help.

However, Fauci said he started taking a second course of Paxlovid after experiencing symptoms “much worse than in the first go around.”

Now near completion of the five-day oral treatment, he said he was still enduring symptoms but felt “reasonably good.”

Finally, as we reported less than two weeks ago, Pfizer stopped enrolling in a clinical trial for Paxlovid for standard-risk COVID-19 patients after the latest results suggested the drug did not reduce symptoms or hospitalizations and deaths to a statistically significant degree.

Watch the full interview below: (forward to around 5:26:00):

Not exactly encouraging news...

Tyler Durden Wed, 06/29/2022 - 11:45

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