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Army researchers look to reduce rotorcraft noise

Experimental, simulation results reveal how coaxial, co-rotating rotors may lead to a quieter hoverCredit: U.S. Army ABERDEEN PROVING GROUND, Md.

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Experimental, simulation results reveal how coaxial, co-rotating rotors may lead to a quieter hover

Credit: U.S. Army

ABERDEEN PROVING GROUND, Md. — Imagine a silent helicopter stealthily moving troops and supplies around a future battlefield. U.S. Army researchers look to helicopter noise reduction technology as a top priority in aircraft design.

At the U.S. Army Combat Capabilities Development Command, now known as DEVCOM, Army Research Laboratory, researchers collaborated with Uber and the University of Texas at Austin to investigate the acoustic properties of electric vertical takeoff and landing aircraft, which use distributed electric propulsion to power flight.

These eVTOL vehicles may aid the Army with important tasks such as aerial surveillance and cargo transport; however, they feature smaller rotors than traditional helicopters. As a result, eVTOL rotors may emit a different sound signature that researchers will have to take into consideration.

“The noise you hear from these smaller rotors is generated through fundamentally different physical mechanisms,” said Dr. George Jacobellis, Army research engineer at the laboratory’s Vehicle Technology Directorate. “Traditional modeling techniques need to be improved to account for all of the noise generated so that vehicle designers can be aware of what will actually be heard.”

Standard helicopter noise simulations focus primarily on predicting thickness noise and loading noise, because they constitute the dominant noise sources for large helicopters.

Thickness noise stems from the displacement of the air by the rotor blades, while loading noise occurs when lift and drag forces act on the air that flows around the rotary wings. Together, they make up what experts refer to as tonal noise.

In contrast, Army researchers suspected that eVTOL rotors generate more broadband noise, which refers to sounds caused by turbulence, than tonal noise.

“We didn’t know whether broadband noise was important or not, but we knew that the tonal and broadband noise scaled differently,” Jacobellis said. “We thought that as rotors became smaller there would be some point at which broadband noise would be the dominant source.”

The team confirmed their hypothesis in their research study, which not only measured the acoustic characteristics of various eVTOL rotor configurations but also assessed the modeling capabilities of helicopter noise simulations for eVTOL rotors.

During the field experiment, the researchers set up a test stand with two electrically-powered rotors and recorded the noise generated above and below the rotor plane with nine microphones placed in a circular array surrounding the rotor hub.

For the simulations, the team utilized the Rotorcraft Comprehensive Analysis System coupled with a separate program called PSU-WOPWOP, a routine noise prediction code named after an onomatopoeia for the sound that helicopter blades make.

“RCAS computes the aerodynamic loads, or forces, on the blades as well as the bending and twisting of the blades,” Jacobellis said. “This information is necessary to use as inputs to PSU-WOPWOP, which computes the noise generated by the rotor. Connecting the two programs required a significant amount of work, which was done by our group as well.”

The researchers modeled the broadband noise in PSU-WOPWOP with Pegg’s method, one of the two settings present in the simulation program with the other called Brooks’ method.

While Pegg’s method makes broadband noise predictions based off of experimental data of the entire rotor, Brooks’ method accounts for the unique distribution of lift along the blade.

“[These technologies] are promising in their ability to predict the noise of eVTOL rotors, but we need to do more work to obtain acceptable accuracy,” Jacobellis said. “The next steps are to implement the Brooks method for higher accuracy acoustic predictions and to compare the unsteady loads between the simulation and experiment to check the accuracy of the simulations in predicting the unsteady loads. The Brooks method should be better at capturing unique configurations and loading distributions.”

Researchers also found that co-axial co-rotating rotors, or stacked rotors, may potentially offer better performance and lower noise than a conventional rotor. Unlike conventional rotors which employ blades arranged in a single plane, stacked rotors place blades in multiple planes.

According to the results of their study, stacked rotors with equally spaced rotor blades produced the lowest noise level, around the same level as that of a traditional rotor.

By investigating different values of axial spacing, Army researchers believe that they may uncover a stacked rotor configuration that produces lower noise than the conventional rotor.

“I do think that a stacked rotor can be beneficial for eVTOL applications,” Jacobellis said. “The added degree of freedom for the design will allow for gains in efficiency and control over the acoustic signature, which has been shown in the results. More investigation is needed, however, to quantify the noise reduction with axial spacing.”

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The team published its paper, Experimental and Computational Investigation of Stacked Rotor Acoustics in Hover, in the Vertical Flight Society 76th Annual Forum Proceedings.

http://www.army.mil/article/241151/army_researchers_look_to_reduce_rotorcraft_noise

These eVTOL vehicles may aid the Army with important tasks such as aerial surveillance and cargo transport; however, they feature smaller rotors than traditional helicopters. As a result, eVTOL rotors may emit a different sound signature that researchers will have to take into consideration.

Source: https://bioengineer.org/army-researchers-look-to-reduce-rotorcraft-noise/

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Physical activity reduces cardiovascular risk in rheumatic patients

People with diseases such as rheumatoid arthritis and lupus are more likely to have heart attacks, angina, and strokes. A

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People with diseases such as rheumatoid arthritis and lupus are more likely to have heart attacks, angina, and strokes. A review of the scientific literature on the subject shows that regular exercise improves vascular function in these patients

The risk of developing atherosclerosis – a narrowing of the arteries as cholesterol plaque builds up, leading to obstruction of blood flow – is higher for people with autoimmune rheumatic diseases than for the general population. As a result, they are more likely to have heart attacks and other cardiovascular disorders.

The good news, according to a new study published in Rheumatology, is that regular exercise is a powerful weapon against vascular dysfunction in these patients.

In the article, researchers working in Brazil and the United Kingdom report the results of a systematic review of the scientific literature on the subject. The review, which was supported by FAPESP, covered ten studies involving 355 volunteers with various diseases, such as rheumatoid arthritis, lupus, and spondyloarthritis (inflammation of the spine). The subjects took exercise programs such as walking in a park or on a treadmill, stationary cycling, high-intensity interval training, and muscle building. Most of the programs lasted 12 weeks.

“Our analysis of the results showed that exercise improved small and large vessel endothelial function to a clinically significant extent. Accordingly, we suggested that exercise can be considered ‘medication’ for these patients because of its potential to reduce the incidence of cardiovascular events,” said Tiago Peçanha, first author of the article. Peçanha is a postdoctoral fellow at the University of São Paulo’s Medical School (FM-USP) in Brazil.

These rheumatic diseases, he explained, are the result of an imbalance in the immune system that leads to the production of antibodies against the subject’s own organism, especially joints, muscles, ligaments and tendons. While there is no definitive cure for these diseases, they can be controlled by treatment with anti-inflammatory drugs, immunosuppressants, and biologics (drugs from living sources).

“Treatment doesn’t prevent patients from developing certain co-morbidities. Cardiovascular disease is the most worrisome,” Peçanha said. “The risk of heart attack is twice as high for people with rheumatoid arthritis as for healthy people. For people with lupus or psoriatic arthritis, the incidence of ischemic events [heart attack, angina and stroke] is between twice and five times as high.”

Atherosclerosis develops rapidly in these patients owing to the chronic inflammation associated with rheumatic disease and continuous use of anti-inflammatory drugs. “It all begins with changes in blood vessel structure and function,” Peçanha said. “The arteries gradually harden and stop being able to dilate when necessary. Changes occur above all in the endothelium [the layer of cells lining the interior surface of blood vessels]. Alterations in vascular function, especially endothelial function, are considered initial markers of atherosclerosis for this reason.”

The systematic review showed that exercise improved small and large vessel vascular function in patients with autoimmune rheumatic diseases. However, the authors note that given the small number of studies reviewed the evidence is not sufficient to state categorically that exercise also promotes a structural recovery of damaged arteries.

“This area [physical activity in rheumatology] is still new, so more research is needed to identify the best exercise protocols and investigate such aspects as safety and adherence,” Peçanha said. “In any event, the data in our study underlines the importance of regular exercise to prevent and treat cardiovascular disease in these patients.”

For people with rheumatic disease, as indeed for everyone else, Peçanha recommends at least 150 minutes of moderate to vigorous exercise per week. Aerobic exercise should predominate and be complemented by activities that foster strength and balance.

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About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at http://www.fapesp.br/en and visit FAPESP news agency at http://www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

In the article, researchers working in Brazil and the United Kingdom report the results of a systematic review of the scientific literature on the subject. The review, which was supported by FAPESP, covered ten studies involving 355 volunteers with various diseases, such as rheumatoid arthritis, lupus, and spondyloarthritis (inflammation of the spine). The subjects took exercise programs such as walking in a park or on a treadmill, stationary cycling, high-intensity interval training, and muscle building. Most of the programs lasted 12 weeks.

Source: https://bioengineer.org/physical-activity-reduces-cardiovascular-risk-in-rheumatic-patients/

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An atlas of HIV’s favorite targets in the blood of infected individuals

Gladstone researchers have identified the blood cells most likely to be targeted by HIV during a real-life infectionCredit: Photo: Gladstone

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Gladstone researchers have identified the blood cells most likely to be targeted by HIV during a real-life infection

SAN FRANCISCO, CA–April 27, 2021–In the 40-some years since the beginning of the HIV/AIDS epidemic, scientists have learned a lot about the virus, the disease, and ways to treat it. But one thing they still don’t completely understand is which exact cells are most susceptible to HIV infection.

Without this knowledge, it is difficult to envision targeting these cells to protect the millions of people who encounter the virus for the first time every year, or the infected people in which infection will likely rebound if they go off therapy.

Scientists have known for a long time that the virus homes in on so-called memory CD4+ T cells, a type of cell that helps the human body build lasting immunity against pathogens. But that is still too broad a category to target for therapy.

“CD4+ T cells orchestrate the immune response against all kinds of pathogens, so you can’t just eliminate them to prevent HIV infections,” says Gladstone Associate Investigator Nadia Roan, PhD. “But if you can find the more specific subsets of CD4+ T cells that are highly susceptible to HIV infection, you may be able to specifically target those cells without detrimental side effects.”

Much knowledge about HIV infection comes from in vitro experiments (in a petri dish), where scientists expose CD4+ T cells cultured in the lab to the virus. These cell cultures are not a perfect model for the human body’s complex ecosystems in which infection normally takes place. Might in vitro infection yield a skewed view of the virus’s preference?

To answer this question, Roan and her team compared CD4+ T cells infected in vitro to the CD4+ T cells circulating in the blood of 11 individuals at various stages of infection. Some blood samples were taken before the donors had started treatment with antiretroviral therapy, some after. Yet others came from individuals who had stopped their treatment and were experiencing new rounds of infection.

Using technology they have honed over the years, the researchers established a detailed atlas of the CD4+ T cells in individuals not on antiretroviral treatment, which they have now published in the scientific journal Cell Reports.

“Our work affords novel insight into the basics of how HIV behaves in the human body, rather than just in a lab dish,” says Roan, who is also an associate professor of urology at UC San Francisco. “It informs our understanding of what really happens during an active infection, which is interesting in its own right. Moreover, we know that some infected cells become reservoirs of latent virus, so our work could help us better understand how the reservoir forms during an infection.”

The technology Roan and her team deployed, called CyTOF/PP-SLIDE, distinguishes cells with exquisite precision based on the proteins they contain or carry on their surface. With this information, the scientists can classify CD4+ T cells into myriad subsets, and then determine whether some subsets are more susceptible to infection than others.

A crucial perk of this technology is that it can trace infected cells back to their original state prior to infection.

“That’s important,” says Guorui Xie, PhD, a postdoctoral researcher in Roan’s lab and the first author of the study. “We know that when HIV infects cells, it remodels the cells such that they no longer contain the exact same levels of proteins as they did before infection. With CyTOF/PP-SLIDE, we can identify the uninfected cells that most closely match the infected ones in the same patient. These uninfected cells can give us important information about what the cells targeted by HIV resembled before the virus remodeled them.”

Roan’s team found that remodeling was indeed extensive in blood CD4+ T cells infected in vivo (in people) as well as in vitro. In the process, they made a surprising finding about one of HIV’s preferred targets. Prior studies have suggested that HIV prefers to infect a subtype of CD4+ T cells, called Tfh, and Roan’s team confirmed these cells to be susceptible to HIV. However, they also discovered that the virus can infect non-Tfh cells and remodel them such that they adopt features of Tfh cells.

“This result strikes a cautionary note in our field,” says Roan. “You really can’t tell which cells HIV prefers to target simply by looking at infected cells. You need to know what the cells looked like before remodeling.”

The scientists also found that remodeling causes infected blood cells to alter their surface in ways that may change how they move through the body. Roan prudently speculates that this might help the virus steer infected cells toward sites where it can infect even more cells.

“Whatever its exact purpose, remodeling is probably not just a chance event,” adds Roan. “A virus as small as HIV depends crucially on the resources provided by its host to grow and spread. It’s likely that nothing the virus does to its host cell is an accident.”

The profile of HIV’s favorite cells differed somewhat between in vitro and in vivo infections. Nevertheless, the researchers found one subset of cells that was preferentially infected in both cases, and could become a useful model for further lab studies.

The team also confirmed that not all CD4+ T cells are equally susceptible to HIV infection in vivo, which gives them hope that the most susceptible cells could eventually become targets of preventive interventions.

Xie and Roan are now planning to obtain blood samples from more donors to see whether HIV’s targets differ between a first infection and the return of the virus after a lapse in therapy, or between men and women. Ultimately, they would also like to look at in vivo-infected cells from mucosal tissues such as the gut and genital tract, where most HIV infections begin. But these samples are much harder to procure.

In the meantime, the researchers are making public the atlas of all the cells they have analyzed, along with the dozens of proteins they found to be affected in these cells after HIV infection, which they hope will be a valuable resource for the HIV research community.

“There is still much to discover in this atlas that may help uncover new insights into HIV infection and how it develops, and perhaps lead to the identification of new approaches for HIV/AIDS prevention,” says Roan.

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About the Study

The paper “Characterization of HIV-induced remodeling reveals differences in infection susceptibility of memory CD4+ T cell subsets in vivo” was published in Cell Reports on April 27, 2021: https://www.cell.com/cell-reports/fulltext/S2211-1247(21)00354-5.

Other authors include Xiaoyu Luo, Tongcui Ma, Julie Frouard, Jason Neidleman, and Warner C. Greene from Gladstone Institutes; and Rebecca Hoh and Steven G. Deeks from UC San Francisco.

This work was supported by the National Institutes of Health (R01AI127219, R01AI147777, P01AI131374, and S10-RR028962), the amfAR Institute for HIV Cure Research (109301), the UCSF-Gladstone Center for AIDS Research (P30AI027763), and the James B. Pendleton Charitable Trust.

About Gladstone Institutes

To ensure our work does the greatest good, Gladstone Institutes (https://gladstone.org) focuses on conditions with profound medical, economic, and social impact–unsolved diseases. Gladstone is an independent, nonprofit life science research organization that uses visionary science and technology to overcome disease. It has an academic affiliation with the University of California, San Francisco.

https://gladstone.org/news/atlas-hivs-favorite-targets-blood-infected-individuals

Source: https://bioengineer.org/an-atlas-of-hivs-favorite-targets-in-the-blood-of-infected-individuals/

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Trial of existing antibiotic for treating Staphylococcus aureus Bacteremia begins

NIH-supported trial will test Dalbavancin in hospitalized adultsCredit: NIAID A clinical trial to test the antibiotic dalbavancin for safety and

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A clinical trial to test the antibiotic dalbavancin for safety and efficacy in treating complicated Staphylococcus aureus (S. aureus) bacteremia has begun. The trial will enroll 200 adults hospitalized with complicated S. aureus infection at approximately 20 trial sites around the United States. The trial is being sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

S. aureus is a leading cause of antibiotic-resistant infection. S. aureus infections led to nearly 20,000 deaths in 2017 in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC). This bacterium is of particular concern in healthcare-associated infections. S. aureus bacteremia–an infection of the blood–often requires inserting a central intravenous (IV) catheter to deliver long courses of antibiotics, an invasive procedure that can involve long-term care in healthcare facilities.

“As antibiotic-resistant infections become more widespread, better and easier treatment regimens are needed to ease the burden on both healthcare providers and patients,” said NIAID Director Anthony S. Fauci, M.D. “By investigating existing antibiotics for their action on a broader array of bacterial infections, we may be able to generate new treatment regimens more efficiently.”

The antibiotic dalbavancin has strong activity against gram-positive bacteria, including methicillin-resistant S. aureus, which suggests it could be an effective treatment for S. aureus bacteremia. Dalbavancin is currently FDA-approved in the United States for treating acute bacterial skin and skin structure infections, including those caused by S. aureus. If the two-dose regimen being tested in this trial proves effective, it could lead to a shorter, less invasive treatment for S. aureus bacteremia that does not require an indwelling IV access for daily therapy.

The Phase 2b trial is being conducted by the NIAID-funded Antibacterial Resistance Leadership Group (ARLG) under the leadership of Thomas Holland, M.D., of Duke University (Durham, North Carolina.) It is called the “Dalbavancin as an Option for Treatment of S. aureus Bacteremia (DOTS)” trial. Patients who have stabilized after initial treatment of their bacteremia will be eligible for enrollment in this study.

“Dalbavancin is appealing as a potential option for treatment of these serious S. aureus infections, and we need high quality data to find out if it works,” said Dr. Holland, “This trial will provide clinicians and patients with that data.”

One hundred participants will be randomized to receive the standard of care for complicated infections, including appropriate antibiotics, and 100 participants will receive two doses of dalbavancin intravenously. The doses will be given one week apart. Most participants receiving dalbavancin will be given 1500 milligrams (mg) per dose. Participants with signs of kidney dysfunction will be given 1125 mg per dose. All participants will be followed for approximately 70 days after enrollment, and up to six months if they have vertebral osteomyelitis, an infection of the vertebrae.

At the end of the trial, multiple patient outcomes will be assessed: survival; additional complications (such as relapse) or clinical failures; drug-related adverse events; and overall quality of life. The therapeutic regimen will have met the primary endpoint of the trial if participants who received dalbavancin fare better on these metrics than those who received the current standard of care. This trial could validate a dalbavancin regimen of only one dose a week for two weeks, compared to daily doses administered intravenously for four to six weeks with the current standard of care.

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The ARLG is a clinical research consortium working to reduce the impact of antimicrobial resistance. It is funded through NIH grant UM1AI104681. For more information about this trial, visit ClinicalTrials.gov and search identifiers NCT04775953.

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NIAID conducts and supports research–at NIH, throughout the United States, and worldwide–to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.

About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.

NIH…Turning Discovery Into Health®

Source: https://bioengineer.org/trial-of-existing-antibiotic-for-treating-staphylococcus-aureus-bacteremia-begins/

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