fbpx
Connect with us

The Conversation

Pooling multiple models during COVID-19 pandemic provided more reliable projections about an uncertain future

Published

on

Pooling multiple models during COVID-19 pandemic provided more reliable projections about an uncertain future

The sum is greater than the parts when researchers build an ensemble from multiple coordinated but independent models.
Matteo Chinazzi, CC BY-ND

Emily Howerton, Penn State; Cecile Viboud, National Institutes of Health, and Justin Lessler, University of North Carolina at Chapel Hill

How can anyone decide on the best course of action in a world full of unknowns?

There are few better examples of this than the pandemic, when fervently potential outcomes as they weighed options like whether to implement lockdowns or require masks in schools. The main tools they used to compare these futures were epidemic models.

But often, models included numerous unstated assumptions and considered only one scenario – for instance, that lockdowns would continue. Chosen scenarios were rarely consistent across models. All this variability made it difficult to compare models, because it’s unclear whether the differences between them were due to different starting assumptions or scientific disagreement.

In response, we came together with colleagues to found the U.S. COVID-19 Scenario Modeling Hub in December 2020. We provide real-time, long-term projections in the U.S. for use by federal agencies such as the Centers for Disease Control and Prevention, local health authorities and the public. We work directly with public health officials to identify which possible futures, or scenarios, would be most helpful to consider as they set policy, and we convene multiple independent modeling teams to make projections of public health outcomes for each scenario. Crucially, multiple teams address the same question allows us to better envision what could possibly happen in the future.

Advertisement

Since its inception, the Scenario Modeling Hub has generated 17 rounds of projections of COVID-19 cases, hospitalizations and deaths in the U.S. across varying stages of the pandemic. In a recent study published in the journal Nature Communications, we looked back at all these projections and evaluated how well they matched the reality that unfolded. This work provided insights about when and what kinds of model projections are most trustworthy – and most importantly supported our strategy of combining multiple models into one ensemble.

line graph that ends in multiple colored options on the right
Collecting projections from multiple independent models provides a fuller picture of possible futures − as in this graph of potential hospitalizations − and allows researchers to generate an ensemble.
COVID-19 Scenario Modeling Hub, CC BY-ND

Multiple models are better than just one

A founding principle of our Scenario Modeling Hub is that multiple models are more reliable than one.

From tomorrow’s temperature on your weather app to predictions of interest rates in the next few months, you likely use the combined results of multiple models all the time. Especially in times like the COVID-19 pandemic when uncertainty abounds, combining projections from multiple models into an ensemble provides a fuller picture of what could happen in the future. Ensembles have become ubiquitous in many fields, primarily because they work.

Our analysis of this approach with COVID-19 models resoundingly showed the strong performance of the Scenario Modeling Hub ensemble. Not only did the ensemble give us more accurate predictions of what could happen in the future overall, it was substantially more consistent than any individual model throughout the different stages of the pandemic. When one model failed, another performed well, and by taking into account results from all of these varying models, the ensemble emerged as more accurate and more reliable.

Advertisement

Researchers have previously shown performance benefits of ensembles for short-term forecasts of influenza, dengue and SARS-CoV-2. But our recent study is one of the first times researchers have tested this effect for long-term projections of alternative scenarios.

A ‘hub’ makes multimodel projections possible

While scientists know combining multiple models into an ensemble improves predictions, it can be tricky to put an ensemble together. For example, in order for an ensemble to be meaningful, model outputs and key assumptions need to be standardized. If one model assumes a new COVID-19 variant will gain steam and another model does not, they will up with vastly different results. Likewise, a model that projects cases and one that projects hospitalizations would not provide comparable results.

people seated around an open conference table with whiteboards
Meeting frequently helps multiple modeling teams stay on the same page.
Matteo Chinazzi, CC BY-ND

Many of these challenges are overcome by convening as a “hub.” Our modeling teams meet weekly to make sure we’re all on the same page about the scenarios we model. This way, any differences in what individual models are the result of things researchers truly do not know. Retaining this scientific disagreement is essential; the of the Scenario Modeling Hub ensemble arises because each modeling team takes a different approach.

At our hub we work together to design our scenarios strategically and in close collaboration with public health officials. By projecting outcomes under specific scenarios, we can estimate the impact of particular interventions, like vaccination.

For example, a scenario with higher vaccine uptake can be compared with a scenario with current vaccination rates to understand how many lives could potentially be saved. Our projections have informed recommendations of COVID-19 vaccines for children and bivalent boosters for all age groups, both in 2022 and 2023.

Advertisement

In other cases, we design scenarios to explore the effects of important unknowns, such as the impact of a new variant – known or hypothetical. These types of scenarios can individuals and institutions know what they might be up against in the future and plan accordingly.

Although the hub process requires substantial time and resources, our results showed that the effort has clear payoffs: The information we generate together is more reliable than the information we could generate alone.

woman filling out a form with a COVID vaccine sign in the foreground
What models suggest are likely futures can inform real-world decisions, such as when to run a vaccine clinic.
Eric Lee for The Washington Post via Getty Images

Past reliability, confidence for future

Because Scenario Modeling Hub projections can inform real public health decisions, it is essential that we provide the best possible information. Holding ourselves accountable in retrospective evaluations not only allows us to identify places where the models and the scenarios can be improved, but also helps us build trust with the people who rely on our projections.

Our hub has expanded to produce scenario projections for influenza, and we are introducing projections of respiratory syncytial virus, or RSV. And encouragingly, other groups abroad, particularly in the EU, are replicating our setup.

Scientists around the world can take the hub-based approach that we’ve shown improves reliability during the COVID-19 pandemic and use it to a comprehensive public health response to important pathogen threats.The Conversation

Emily Howerton, Postdoctoral Scholar in Biology, Penn State; Cecile Viboud, Senior Research Scientist, National Institutes of Health, and Justin Lessler, Professor of Epidemiology, University of North Carolina at Chapel Hill

Advertisement

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

The Conversation

Pagers and walkie-talkies over cellphones – a security expert explains why Hezbollah went low-tech for communications

Published

on

theconversation.com – Richard Forno, Principal Lecturer in Computer Science and Electrical Engineering, University of Maryland, Baltimore County – 2024-09-18 16:32:21

A police officer examines a damaged car after thousands of pagers exploded simultaneously across Lebanon on Sept. 17, 2024.
AP Photo/Hussein Malla

Richard Forno, University of Maryland, Baltimore County

Electronic pagers across Lebanon exploded simultaneously on Sept. 17, 2024, killing 12 and wounding more than 2,700. The day, another wave of explosions in the country came from detonating walkie-talkies. The attacks appeared to target members of the militant group Hezbollah.

The pagers attack involved explosives planted in the communications devices by Israeli operatives, according to U.S. officials cited by The New York Times. Hezbollah had recently ordered a shipment of pagers, according to the .

Advertisement

Secretly attacking the supply chain is not a new technique in intelligence and military operations. For example, the U.S. National Security Agency intercepted computer hardware bound for overseas customers, inserted malware or other surveillance tools and then repackaged them for delivery to certain foreign buyers, a 2010 NSA internal document showed. This differs from accessing a specific person’s device, such as when Israel’s Shin Bet secretly inserted explosives into a cellphone to remotely kill a Hamas bombmaker in 1996.

Hezbollah, a longtime adversary of Israel, had increased its use of pagers in the wake of the Hamas attack on Israel on Oct. 7, 2023. By shifting to relatively low-tech communication devices, including pagers and walkie-talkies, Hezbollah apparently sought an advantage against Israel’s well-known sophistication in tracking targets through their phones.

pieces of a destroyed electronic device
The second wave of explosions in Lebanon involved walkie-talkies.
AP Photo

Cellphones: The ultimate tracker

As a former cybersecurity professional and current security researcher, I view cellular devices as the ultimate tracking tool for both and commercial entities – in addition to users, criminals and the mobile phone provider itself. As a result, mobile phone tracking has contributed to the fight against terrorism, located missing people and helped solve crimes.

Conversely, mobile phone tracking makes it easy for anyone to record a person’s most intimate movements. This can be done for legitimate purposes such as tracking children’s movements, helping you find your car in a parking lot, and commercial advertising, or nefarious ends such as remotely spying on a lover suspected of cheating or tracking political activists and journalists. Even the U.S. military remains concerned with how its soldiers might be tracked by their phones.

Mobile device tracking is conducted in several ways. First, there is the network location data generated by the phone as it moves past local cell towers or Stingray devices, which law enforcement agencies use to mimic cell towers. Then there are the features built into the phone’s operating system or enabled by downloaded apps that may lead to highly detailed user tracking, which users unwittingly agree to by ignoring the software’s privacy policy or terms of service.

Advertisement

This collected data is sometimes sold to governments or other companies for additional data mining and user profiling. And modern smartphones also have built-in Bluetooth, Wi-Fi and GPS capabilities that can with locating and tracking user movements around the world, both from the ground and via satellites.

Your phone contains many sensors that make it useful – and easy to track.

Mobile devices can be tracked in real time or close to it. Common technical methods include traditional radio direction-finding techniques, using intelligence satellites or drones, deploying “man in the middle” tools like Stingrays to impersonate cellular towers to intercept and isolate device traffic, or installing malware such as Pegasus, made by Israeli cyberarms company NSO to report a device’s location.

Nontechnical and slower techniques of user tracking include potentially identifying general user locations from their internet activity. This can be done from website logs or the metadata contained in content posted to social media, or contracting with data brokers to any collected location data from the apps that a user might install on their device.

Indeed, because of these vulnerabilities, the leader of Hezbollah earlier this year advised his members to avoid using cellular phones in their activities, noting that Israel’s “surveillance devices are in your pockets. If you are looking for the Israeli agent, look at the phone in your hands and those of your wives and children.”

Advertisement

Researchers have shown how these features, often intended for the user’s convenience, can be used by governments, companies and criminals to track people in their daily lives and even predict movements. Many people still aren’t aware of how much their mobile devices disclose about them.

Pagers, however, unlike mobile phones, can be harder to track depending on whether they two-way communication.

Why go low-tech

A pager that only receives messages does not provide a signal that can facilitate tracking its owner. Therefore, Hezbollah’s use of pagers likely made it more challenging to track their operatives – thus motivating Israeli intelligence services’ purported attack on the supply chain of Hezbollah’s pagers.

Using low-tech tactics and personal couriers while avoiding the use of mobile phones and digital tools also made it difficult for the technologically superior Western intelligence agencies to locate Osama bin Laden for years after the 9/11 attacks.

Advertisement

In general, I believe the adversary in an asymmetric conflict using low-tech techniques, tactics and technology will almost always be able to operate successfully against a more powerful and well-funded opponent.

A well-documented demonstration of this asymmetry in action was the U.S. military’s Millennium Challenge war game in 2002. Among other things, the insurgent Red forces, led by Marine General Paul van Riper, used low-tech tactics including motorcycle couriers instead of cellphones to evade the Blue forces’ high-tech surveillance. In the initial of the exercise, the Red team won the contest in 24 hours, forcing exercise planners to controversially reset and the scenario to ensure a Blue team victory.

Lessons for everyone

The preference for terrorist organizations like Hezbollah and al-Qaida to avoid using smartphones is a reminder for everyone that you can be, and likely are being tracked in various ways and for various purposes.

Israel’s purported response to Hezbollah’s actions also a lesson for everyone. From a cybersecurity perspective, it shows that any device in your life can be tampered with by an adversary at points along the supply chain – long before you even receive it.The Conversation

Richard Forno, Principal Lecturer in Computer Science and Electrical Engineering, University of Maryland, Baltimore County

Advertisement

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

Read More

The post Pagers and walkie-talkies over cellphones – a security expert explains why Hezbollah went low-tech for communications appeared first on theconversation.com

Advertisement
Continue Reading

The Conversation

Tiny robots and AI algorithms could help to craft material solutions for cleaner environments

Published

on

theconversation.com – Mahshid Ahmadi, Assistant Professor of Materials Science and Engineering, of Tennessee – 2024-09-17 07:31:57

pollution is a global problem, but scientists are investigating new materials that could help clean it up.
AP Photo/Sergei Grits

Mahshid Ahmadi, University of Tennessee

Many human activities release pollutants into the air, and soil. These harmful chemicals threaten the of both people and the ecosystem. According to the World Health Organization, air pollution causes an estimated 4.2 million deaths annually.

Scientists are looking into , and one potential avenue is a class of materials called photocatalysts. When triggered by light, these materials undergo chemical reactions that initial studies have shown can break down common toxic pollutants.

Advertisement

I am a materials science and engineering researcher at the University of Tennessee. With the help of robots and artificial intelligence, my colleagues and I are making and testing new photocatalysts with the goal of mitigating air pollution.

Breaking down pollutants

The photocatalysts work by generating charged carriers in the presence of light. These charged carriers are tiny particles that can move around and cause chemical reactions. When they into contact with water and oxygen in the , they produce substances called reactive oxygen species. These highly active reactive oxygen species can bond to parts of the pollutants and then either decompose the pollutants or turn them into harmless – or even useful – products.

A cube-shaped metal machine with a chamber filled with bright light, and a plate of tubes shown going under the light.
To facilitate the photocatalytic reaction, researchers in the Ahmadi lab put plates of perovskite nanocrystals and pollutants under bright light to see whether the reaction breaks down the pollutants.
Astita Dubey

But some materials used in the photocatalytic have limitations. For example, they can’t start the reaction unless the light has enough energy – infrared rays with lower energy light, or visible light, won’t trigger the reaction.

Another problem is that the charged particles involved in the reaction can recombine too quickly, which means they join back together before finishing the job. In these cases, the pollutants either do not decompose completely or the process takes a long time to accomplish.

Additionally, the surface of these photocatalysts can sometimes change during or after the photocatalytic reaction, which affects how they work and how efficient they are.

Advertisement

To overcome these limitations, scientists on my team are to develop new photocatalytic materials that work efficiently to break down pollutants. We also focus on making sure these materials are nontoxic so that our pollution-cleaning materials aren’t causing further pollution.

A plate of tiny tubes, with some colored dark blue, others light blue, and others transparent.
This plate from the Ahmadi lab is used while testing how perovskite nanocrystals and light break down pollutants, like the blue dye shown. The light blue color indicates partial degradation, while transparent water signifies complete degradation.
Astita Dubey

Teeny tiny crystals

Scientists on my team use automated experimentation and artificial intelligence to figure out which photocatalytic materials could be the best candidates to quickly break down pollutants. We’re making and testing materials called hybrid perovskites, which are tiny crystals – they’re about a 10th the thickness of a strand of hair.

These nanocrystals are made of a blend of organic (carbon-based) and inorganic (non-carbon-based) components.

They have a few unique qualities, like their excellent light-absorbing properties, which come from how they’re structured at the atomic level. They’re tiny, but mighty. Optically, they’re amazing too – they interact with light in fascinating ways to generate a large number of tiny charge carriers and trigger photocatalytic reactions.

These materials efficiently transport electrical charges, which allows them to transport light energy and the chemical reactions. They’re also used to make solar panels more efficient and in LED lights, which create the vibrant displays you see on TV screens.

Advertisement

There are thousands of potential types of hybrid nanocrystals. So, my team wanted to figure out how to make and test as many as we can quickly, to see which are the best candidates for cleaning up toxic pollutants.

Bringing in robots

Instead of making and testing samples by hand – which takes weeks or months – we’re using smart robots, which can produce and test at least 100 different materials within an hour. These small liquid-handling robots can precisely move, mix and transfer tiny amounts of liquid from one place to another. They’re controlled by a computer that guides their acceleration and accuracy.

A researcher in a white lab coat smiling at the camera next to a fume hood, with plates of small tubes inside it.
The Opentrons pipetting robot helps Astita Dubey, a visiting scientist working with the Ahmadi lab, synthesize materials and treat them with organic pollutants to test whether they can break down the pollutants.
Jordan Marshall

We also use machine learning to guide this process. Machine learning algorithms can analyze test data quickly and then learn from that data for the next set of experiments executed by the robots. These machine learning algorithms can quickly identify patterns and insights in collected data that would normally take much longer for a human eye to catch.

Our approach aims to simplify and better understand complex photocatalytic systems, helping to create new strategies and materials. By using automated experimentation guided by machine learning, we can now make these systems easier to analyze and interpret, overcoming challenges that were difficult with traditional methods.The Conversation

Mahshid Ahmadi, Assistant Professor of Materials Science and Engineering, University of Tennessee

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

Advertisement

Read More

The post Tiny robots and AI algorithms could help to craft material solutions for cleaner environments appeared first on theconversation.com

Continue Reading

The Conversation

A public health historian sizes up their records

Published

on

theconversation.com – Zachary W. Schulz, Lecturer of History, Auburn – 2024-09-17 07:33:53

The presidential debate on Sept. 10, 2024, did not add much context to what the two candidates would do on care beyond their own .
Visual China Group/Getty Images

Zachary W. Schulz, Auburn University

is a defining issue in the 2024 election – Democratic presidential nominee Kamala Harris and Republican contender Donald Trump have starkly different records on the issue. Rather than focusing on what they promise to do, let’s examine what their past actions reveal about their approaches to Medicare, the Affordable Care Act, public health , drug policy and child abuse and domestic violence prevention.

As a specialist in public health history and policy, I have carefully examined both candidates’ records on American health care. With years of experience in the health care field and being a cystic fibrosis patient myself, I have developed a deep understanding of our health care system and the political dynamics that shape it.

Advertisement

For me, as for many other Americans, health care is more than just a political issue; it is a deeply personal one.

Medicare

During Harris’ time in the Senate, she co-sponsored the Medicare for All Act, which aimed to expand Medicare to all Americans, effectively eliminating private insurance.

At the presidential debate on Sept. 10, 2024, Harris clarified her former of “Medicare for All” by emphasizing her prior legislative efforts to preserve and expand protections for ‘ rights and access to affordable health care.

Harris’s legislative efforts, primarily around the 2017-2020 period, reflect a commitment to broadening access to Medicare and reducing costs for seniors. During that time, Harris advocated for the Medicare program to negotiate drug prices directly with pharmaceutical companies.

Advertisement

Later, as vice president, Harris cast a tie-breaking vote on the 2022 Inflation Reduction Act, allowing the government to negotiate drug prices for Medicare with pharmaceutical companies.

In contrast, during Trump’s presidency, he made several attempts, some of which were successful, to cut funding for Medicare. The 2020 budget proposed by his administration included cuts to Medicare totaling more than US$800 billion over 10 years, primarily by reducing payments to providers and slowing the growth of the program.

The proposed cuts did not take effect because they required Congressional approval, which was not granted. The plan faced significant opposition due to concerns about potential negative impacts on beneficiaries.

Affordable Care Act

Harris has been a staunch defender of the Affordable Care Act, also known as the ACA or “Obamacare.” As a senator, Harris consistently voted against any efforts to repeal the ACA. She advocated for expanding its provisions, supporting legislation that aimed to strengthen protections for people with preexisting conditions and increase funding for Medicaid expansion.

Advertisement

Harris’ record shows a clear commitment to ensuring broader health coverage under the ACA. And, in the recent debate, Harris noted this record and reasserted her commitment to the act.

During his presidency, Trump led multiple efforts to repeal the ACA, including the 2017 American Health Care Act, which would have significantly reduced the scope of Medicaid expansion and removed individual mandates.

Although these efforts ultimately failed in the Senate, Trump succeeded in weakening the ACA by eliminating the individual mandate penalty through the 2017 Tax Cuts and Jobs Act. In the debate against Harris, Trump reiterated his position that the Affordable Care Act “was lousy health care,” though he did not ultimately offer a replacement plan, stating only that he has “concepts of a plan.”

Donald Trump claims that as president, he had an obligation to save Obamacare, otherwise known as the Affordable Care Act, but says it is too expensive. He says he has ‘concepts of a plan’ for something to replace the ACA.

Public health infrastructure

Harris’ tenure in the Senate, from January 2017 to January 2021, shows a consistent pattern of supporting public health infrastructure. She co-sponsored several bills aimed at increasing funding for community health centers and expanding access to preventive care.

Advertisement

Harris also advocated for more federal funding to address public health emergencies, such as the opioid epidemic and the COVID-19 pandemic.

During Trump’s presidency, however, he made significant cuts to public health programs. The Trump administration proposed budget cuts to the Centers for Disease Control and Prevention and other public health agencies, arguing that they were necessary for fiscal responsibility. These proposals drew criticism for potentially undermining the nation’s ability to respond to public health emergencies, a concern that was underscored by the CDC’s struggles during the early days of the COVID-19 pandemic. Trump frequently has responded to these criticisms by asserting he “cut bureaucratic red tape” rather than essential services.

Drug pricing policy

Harris has also supported legislation to lower drug prices and increase transparency in the pharmaceutical industry. She co-sponsored the Drug Price Relief Act, which aimed to allow the federal government to negotiate drug prices for Medicare directly. She also supported efforts to import cheaper prescription from Canada. Her record reflects a focus on reducing costs for consumers and increasing access to affordable medications.

Trump’s record on drug policy is mixed. While Trump took credit for some decreases in prescription drug prices during his presidency, his administration’s most significant regulatory changes favored pharmaceutical companies. The administration’s attempts to implement a rule allowing the importation of cheaper drugs from Canada faced significant hurdles and did not lead to immediate changes.

Advertisement

Trump also ended a rule that would have required pharmaceutical companies to disclose drug prices in television ads, citing concerns over its legality.

Child abuse and domestic violence

Harris has a strong record of advocating for the prevention of child abuse and domestic violence. During her time as California’s attorney general and as a senator, Harris pushed for legislation that increased funding for domestic violence prevention programs and expanded legal protections for survivors. She has consistently supported measures to enhance child welfare services and improve coordination among agencies to protect children.

Trump’s record on these issues is less defined, but his administration did sign into law the Family First Prevention Services Act, which aimed to keep more safely at home and out of foster care by providing new resources to families. However, critics argue that the Trump administration’s broader cuts to social services and health programs could indirectly undermine efforts to combat child abuse and domestic violence. In addition, some experts suggest that Trump’s family separation policies on the southern border contributed to an increase in child trauma during his administration.The Conversation

Zachary W. Schulz, Lecturer of History, Auburn University

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

Advertisement

Read More

The post A public health historian sizes up their records appeared first on theconversation.com

Continue Reading

Trending