Science

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The Delta IV Heavy, a rocket whose time has come and gone, will fly once more

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United Launch Alliance's final Delta IV Heavy rocket, seen here in December when ground crews rolled it to the launch pad at Cape Canaveral Space Force Station, Florida.

Enlarge / United Launch Alliance’s final Delta IV Heavy rocket, seen here in December when ground crews rolled it to the launch pad at Cape Canaveral Space Force Station, Florida.

This is the rocket that literally lights itself on fire before it heads to space. It’s the world’s largest rocket entirely fueled by liquid hydrogen, a propellant that is vexing to handle but rewarding in its efficiency.

The Delta IV Heavy was America’s most powerful launch vehicle for nearly a decade and has been a cornerstone for the US military’s space program for more than 20 years. It is also the world’s most expensive commercially produced rocket, a fact driven not just by its outsized capability but also its complexity.

Now, United Launch Alliance’s last Delta IV Heavy rocket is set to lift off Thursday from Cape Canaveral Space Force Station, Florida, with a classified payload for the National Reconnaissance Office, the US government’s spy satellite agency.

“This is such an amazing piece of technology, 23 stories tall, a half-million gallons of propellant and a quarter-million pounds of thrust, and the most metal of all rockets, setting itself on fire before it goes to space,” said Tory Bruno, ULA’s president and CEO. “Retiring it is (key to) the future, moving to Vulcan, a less expensive higher-performance rocket. But it’s still sad.”

45th and final Delta IV

Weather permitting, the Delta IV Heavy will light up its three hydrogen-fueled RS-68A engines at 1: 40 pm EDT (17: 40 UTC) Thursday, the opening of a four-hour launch window. The three RS-68s will fire up in a staggered sequence, a permutation designed to minimize the hydrogen fireball that ignites around the base of the rocket during engine startup.

The Delta IV Heavy will certainly have a legacy of launching national security missions, along with NASA’s Orion spacecraft on an orbital test flight in 2014 and NASA’s Parker Solar Probe in 2018 on a mission to fly through the Sun’s outer atmosphere.

But the fireball will leave an indelible mark in the memories of anyone who saw a Delta IV Heavy launch. It all comes down to the choice of super-cold liquid hydrogen as the fuel. The three RS-68 engines burn hydrogen along with liquid oxygen as the oxidizer.

“We like those propellants because they’re very, very high performance,” Bruno said. “In order to prepare the RS-68 engines to get that very cold cryogenic propellant flowing through them, before they’re ignited, we start flowing that propellant.

“Hydrogen is lighter than air, so after it flows through the engine and into the flame trench, it then rises. When the engines are finally full and ready to go and we start spinning up the pumps, then we actually drop the main load (of propellant), we ignite it, and that flame carries on up that … plume of hydrogen, which is clinging to the side of the booster and rising up.”

The Delta IV rocket cores are covered in orange foam insulation. One of the reasons for this is to protect the rocket from the fireball, leading to a “very dramatic effect of a self-immolating booster” that has the appearance of a “toasted marshmallow” as it heads to space.

A few seconds after the engines start, 12 hold-down bolts will blow to release the triple-core rocket from its restraints. More than 2 million pounds of thrust will power the Delta IV Heavy off the launch pad toward the east from Cape Canaveral. The RS-68 on the center core will throttle down to conserve liquid hydrogen and liquid hydrogen propellant, while the rocket’s two side boosters will burn through their propellants in less than four minutes.

Once the Delta IV lets go of its side boosters and falls into the Atlantic Ocean, the center core throttles up and burns for another minute and a half. A few moments later, the first stage booster jettisons, and the upper stage’s RL10 engine ignites for the first of three burns needed to propel the rocket’s classified cargo into an orbit thousands of miles above Earth.

There’s just a 30 percent chance of favorable weather for liftoff Thursday. High winds and cumulus clouds are the primary concerns. The weather forecast improves for a backup launch opportunity Friday afternoon.

The Delta IV Heavy, a rocket whose time has come and gone, will fly once more Read More »

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Quantum computing progress: Higher temps, better error correction

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conceptual graphic of symbols representing quantum states floating above a stylized computer chip.

There’s a strong consensus that tackling most useful problems with a quantum computer will require that the computer be capable of error correction. There is absolutely no consensus, however, about what technology will allow us to get there. A large number of companies, including major players like Microsoft, Intel, Amazon, and IBM, have all committed to different technologies to get there, while a collection of startups are exploring an even wider range of potential solutions.

We probably won’t have a clearer picture of what’s likely to work for a few years. But there’s going to be lots of interesting research and development work between now and then, some of which may ultimately represent key milestones in the development of quantum computing. To give you a sense of that work, we’re going to look at three papers that were published within the last couple of weeks, each of which tackles a different aspect of quantum computing technology.

Hot stuff

Error correction will require connecting multiple hardware qubits to act as a single unit termed a logical qubit. This spreads a single bit of quantum information across multiple hardware qubits, making it more robust. Additional qubits are used to monitor the behavior of the ones holding the data and perform corrections as needed. Some error correction schemes require over a hundred hardware qubits for each logical qubit, meaning we’d need tens of thousands of hardware qubits before we could do anything practical.

A number of companies have looked at that problem and decided we already know how to create hardware on that scale—just look at any silicon chip. So, if we could etch useful qubits through the same processes we use to make current processors, then scaling wouldn’t be an issue. Typically, this has meant fabricating quantum dots on the surface of silicon chips and using these to store single electrons that can hold a qubit in their spin. The rest of the chip holds more traditional circuitry that performs the initiation, control, and readout of the qubit.

This creates a notable problem. Like many other qubit technologies, quantum dots need to be kept below one Kelvin in order to keep the environment from interfering with the qubit. And, as anyone who’s ever owned an x86-based laptop knows, all the other circuitry on the silicon generates heat. So, there’s the very real prospect that trying to control the qubits will raise the temperature to the point that the qubits can’t hold onto their state.

That might not be the problem that we thought, according to some work published in Wednesday’s Nature. A large international team that includes people from the startup Diraq have shown that a silicon quantum dot processor can work well at the relatively toasty temperature of 1 Kelvin, up from the usual milliKelvin that these processors normally operate at.

The work was done on a two-qubit prototype made with materials that were specifically chosen to improve noise tolerance; the experimental procedure was also optimized to limit errors. The team then performed normal operations starting at 0.1 K, and gradually ramped up the temperatures to 1.5 K, checking performance as they did so. They found that a major source of errors, state preparation and measurement (SPAM), didn’t change dramatically in this temperature range: “SPAM around 1 K is comparable to that at millikelvin temperatures and remains workable at least until 1.4 K.”

The error rates they did see depended on the state they were preparing. One particular state (both spin-up) had a fidelity of over 99 percent, while the rest were less constrained, at somewhere above 95 percent. States had a lifetime of over a millisecond, which qualifies as long-lived int he quantum world.

All of which is pretty good, and suggests that the chips can tolerate reasonable operating temperatures, meaning on-chip control circuitry can be used without causing problems. The error rates of the hardware qubits are still well above those that would be needed for error correction to work. However, the researchers suggest that they’ve identified error processes that can potentially be compensated for. They expect that the ability to do industrial-scale manufacturing will ultimately lead to working hardware.

Quantum computing progress: Higher temps, better error correction Read More »

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Puerto Rico declares public health emergency as dengue cases rise

Aedes aegypti, dengue, health, Infectious disease, mosquitoes, Puerto Rico, Science, viral infection / /

emergency —

Cases so far are up 140 percent compared to this point last year.

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Female Aedes aegypti mosquito as she was in the process of obtaining a

Female Aedes aegypti mosquito as she was in the process of obtaining a “blood meal.”

Puerto Rico has declared a public health emergency amid an ongoing outbreak of dengue infections, a mosquito-spread viral infection that can cause fever, aches, rash, vomiting, and, in about 5 percent of cases, a severe disease marked by internal bleeding and shock.

The US territory has tallied 549 cases since the start of the year, representing a 140 percent increase compared with cases tallied at this point last year, according to the territory’s health department. The Associated Press reported that more than 340 of the 549 cases have been hospitalized.

In 2023, the island nation of more than 3.2 million people had over 1,000 cases of dengue throughout the year.

But this year’s cases are rising rapidly, leading health officials to warn residents to be vigilant and take prevention measures. That includes wearing insect repellent and draining or treating any standing water where mosquitoes can breed. The mosquitoes that transmit dengue—Aedes aegypti—seem to prefer breeding in artificial containers, such as flower pots, buckets, water drums, vases, plastic containers of any kind, the inner rings of discarded automobile tires, and trash in general. They can breed in tiny amounts of water, such as in bottle caps.

Puerto Rico’s outbreak of dengue is part of a larger regional trend, the island’s health department noted. Last year, the Americas saw the highest number of dengue cases ever recorded, totaling 4,565,911, according to the Pan American Health Organization (PAHO), a division of the World Health Organization. So far this year, the region has reported 3,578,414 cases, including 1,039 deaths. The bulk of the cases are in Brazil, which has reported over 2.9 million cases so far. Paraguay has reported over 191,000 cases, and Argentina has reported over 134,000 cases.

In a December 2023 risk assessment, the PAHO deemed the risk to human health from dengue to be “high” in the region. The report noted that the effects of climate change are driving higher rainfall, higher temperatures, and more humidity, allowing A. aegypti to expand into new areas and increase breeding. A. aegypti are already found in much of South America, Central America, and the southeastern US.

This post was updated to include additional case tallies. 

Puerto Rico declares public health emergency as dengue cases rise Read More »

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Event Horizon Telescope captures stunning new image of Milky Way’s black hole

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A new image from the Event Horizon Telescope has revealed powerful magnetic fields spiraling from the edge of a supermassive black hole at the center of the Milky Way, Sagittarius A*.

Enlarge / A new image from the Event Horizon Telescope has revealed powerful magnetic fields spiraling from the edge of a supermassive black hole at the center of the Milky Way, Sagittarius A*.

EHT Collaboration

Physicists have been confident since the1980s that there is a supermassive black hole at the center of the Milky Way galaxy, similar to those thought to be at the center of most spiral and elliptical galaxies. It’s since been dubbed Sagittarius A* (pronounced A-star), or SgrAfor short. The Event Horizon Telescope (EHT) captured the first image of SgrAtwo years ago. Now the collaboration has revealed a new polarized image (above) showcasing the black hole’s swirling magnetic fields. The technical details appear in two new papers published in The Astrophysical Journal Letters. The new image is strikingly similar to another EHT image of a larger supermassive black hole, M87*, so this might be something that all such black holes share.

The only way to “see” a black hole is to image the shadow created by light as it bends in response to the object’s powerful gravitational field. As Ars Science Editor John Timmer reported in 2019, the EHT isn’t a telescope in the traditional sense. Instead, it’s a collection of telescopes scattered around the globe. The EHT is created by interferometry, which uses light in the microwave regime of the electromagnetic spectrum captured at different locations. These recorded images are combined and processed to build an image with a resolution similar to that of a telescope the size of the most distant locations. Interferometry has been used at facilities like ALMA (the Atacama Large Millimeter/submillimeter Array) in northern Chile, where telescopes can be spread across 16 km of desert.

In theory, there’s no upper limit on the size of the array, but to determine which photons originated simultaneously at the source, you need very precise location and timing information on each of the sites. And you still have to gather sufficient photons to see anything at all. So atomic clocks were installed at many of the locations, and exact GPS measurements were built up over time. For the EHT, the large collecting area of ALMA—combined with choosing a wavelength in which supermassive black holes are very bright—ensured sufficient photons.

In 2019, the EHT announced the first direct image taken of a black hole at the center of an elliptical galaxy, Messier 87, located in the constellation of Virgo some 55 million light-years away. This image would have been impossible a mere generation ago, and it was made possible by technological breakthroughs, innovative new algorithms, and (of course) connecting several of the world’s best radio observatories. The image confirmed that the object at the center of M87is indeed a black hole.

In 2021, the EHT collaboration released a new image of M87showing what the black hole looks like in polarized light—a signature of the magnetic fields at the object’s edge—which yielded fresh insight into how black holes gobble up matter and emit powerful jets from their cores. A few months later, the EHT was back with images of the “dark heart” of a radio galaxy known as Centaurus A, enabling the collaboration to pinpoint the location of the supermassive black hole at the galaxy’s center.

SgrAis much smaller but also much closer than M87*. That made it a bit more challenging to capture an equally sharp image because SgrAchanges on time scales of minutes and hours compared to days and weeks for M87*. Physicist Matt Strassler previously compared the feat to “taking a one-second exposure of a tree on a windy day. Things get blurred out, and it can be difficult to determine the true shape of what was captured in the image.”

Event Horizon Telescope captures stunning new image of Milky Way’s black hole Read More »

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Cows in Texas and Kansas test positive for highly pathogenic bird flu

avian influenza, bird flu, cows, dairy cows, H5N1, health, kansas, milk, Science, texas, USDA / /

viral spread —

The risk to the public is low, and the milk supply is safe.

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Image of cows

Wild migratory birds likely spread a deadly strain of bird flu to dairy cows in Texas and Kansas, state and federal officials announced this week.

It is believed to be the first time the virus, a highly pathogenic avian influenza (HPAI), has been found in cows in the US. Last week, officials in Minnesota confirmed finding an HPAI case in a young goat, marking the first time the virus has been found in a domestic ruminant in the US.

According to the Associated Press, officials with the Texas Animal Health Commission confirmed the flu virus is the Type A H5N1 strain, which has been ravaging bird populations around the globe for several years. The explosive, ongoing spread of the virus has led to many spillover events into mammals, making epidemiologists anxious that the virus could adapt to spread widely in humans.

For now, the risk to the public is low. According to a release from the US Department of Agriculture (USDA), genetic testing by the National Veterinary Services Laboratories indicated that H5N1 strain that spread to the cows doesn’t appear to contain any mutations that would make it more transmissible to humans. Though the flu strain was found in some milk samples from the infected cows, the USDA emphasized that all the milk from affected animals is being diverted and destroyed. Dairy farms are required to send only milk from healthy animals to be processed for human consumption. Still, even if some flu-contaminated milk was processed for human consumption, the standard pasteurization process inactivates viruses, including influenza, as well as bacteria.

So far, officials believe the virus is primarily affecting older cows. The virus was detected in milk from sick cows on two farms in Kansas and one in Texas, as well as in a throat swab from a cow on a second Texas farm. The USDA noted that farmers have found dead birds on their properties, indicating exposure to infected birds. Sick cows have also been reported in New Mexico. Symptoms of the bird flu in cows appear to include decreased milk production and low appetite.

But so far, the USDA believes the spread of H5N1 will not significantly affect milk production or the herds. Milk loss has been limited; only about 10 percent of affected herds have shown signs of the infection, and there has been “little to no associated mortality.” The USDA suggested it will remain vigilant, calling the infections a “rapidly evolving situation.”

While federal and state officials continue to track the virus, Texas officials aim to assure consumers. “There is no threat to the public and there will be no supply shortages,” Texas Agriculture Commissioner Sid Miller said in a statement. “No contaminated milk is known to have entered the food chain; it has all been dumped. In the rare event that some affected milk enters the food chain, the pasteurization process will kill the virus.”

Cows in Texas and Kansas test positive for highly pathogenic bird flu Read More »

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Taylor Swift fans dancing and jumping created last year’s “Swift quakes”

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Good vibrations —

“Shake It Off” produced tremors equivalent to a local magnitude earthquake of 0.851.

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Taylor Swift on the Eras Tour in 2023

Enlarge / Taylor Swift during her Eras Tour. Crowd motions likely caused mini “Swift quakes” recorded by seismic monitoring stations.

When mega pop star Taylor Swift gave a series of concerts last August at the SoFi Stadium in Los Angeles, regional seismic network stations recorded unique harmonic vibrations known as “concert tremor.” A similar “Swift quake” had occurred the month before in Seattle, prompting scientists from the California Institute of Technology and UCLA to take a closer look at seismic data collected during Swift’s LA concert.

The researchers concluded that the vibrations were largely generated by crowd motion as “Swifties” jumped and danced enthusiastically to the music and described their findings in a new paper published in the journal Seismological Research Letters. The authors contend that gaining a better understanding of atypical seismic signals like those generated by the Swift concert could improve the analysis of seismic signals in the future, as well as bolster emerging applications like using signals from train noise for seismic interferometry.

Concert tremor consists of low-frequency signals of extended duration with harmonic frequency peaks between 1 and 10 Hz, similar to the signals generated by volcanoes or trains. There has been considerable debate about the source of these low-frequency concert tremor signals: Are they produced by the synchronized movement of the crowd, or by the sound systems or instruments coupled to the stage? Several prior studies of stadium concerts have argued for the former hypothesis, while a 2015 study found that a chanting crowd at a football game produced similar harmonic seismic tremors. However, a 2008 study concluded that such signals generated during an outdoor electronic dance music festival came from the sound system vibrating to the musical beat.

The Caltech/UCLA team didn’t just rely on the data from the regional network stations. The scientists placed additional motion sensors throughout the stadium prior to the concert, enabling them to characterize all the seismic signals produced during the concert. The signals had such unique characteristics that it was relatively easy to identify them with a spectrogram. In fact, the authors were able to identify 43 of the 45 songs Swift performed based on the distinctive signal of each song.

They also calculated how much radiated energy was produced by each song. “Shake It Off” produced the most radiated energy, equivalent to a local magnitude earthquake of 0.851. “Keep in mind this energy was released over a few minutes compared to a second for an earthquake of that size,” said co-author Gabrielle Tepp of Caltech.

Tepp is a volcanologist and musician in her own right. That combination came in handy when it was time to conduct a lab-based experiment to test the team’s source hypothesis using a portable public announcement speaker system. They played Swift’s “Love Story” and Tepp gamely danced and jumped with the beat during the last chorus while sensors recorded the seismic vibrations. “Even though I was not great at staying in the same place—I ended up jumping around in a small circle, like at a concert—I was surprised at how clear the signal came out,” said Tepp. They also tested a steady beat as Tepp played her bass guitar in order to isolate the signal from a single instrument.

The resulting fundamental harmonic during the jumping was consistent with the song’s beat rate. However, the bass beats didn’t produce a harmonic signal, which was surprising since those beats were better synchronized with the actual musical beats than Tepp’s jumping motions. This might be due to the rounder shape of the bass beat signals compared to sharper spiking signals in response to the jumping.

Map showing the concert venue and nearby seismic stations (circles) that recorded signals from the Swift concerts (blue).

Enlarge / Map showing the concert venue and nearby seismic stations (circles) that recorded signals from the Swift concerts (blue).

Gabrielle Tepp et al., 2024

The authors noted that their experiment did not involve a stage or stadium-grade sound system, “so we cannot completely rule out loudspeakers as a vibrational energy source,” they wrote. Nonetheless, “Overall the evidence suggests that crowd movement is the primary source of the low-frequency signals, with the speaker system or instruments potentially contributing via stage of building vibrations.” The fact that the same kind of low-frequency seismic signals were not detected during pre-concert sound checks seems to support that conclusion, although there were higher frequency signals during sound checks.

The team also studied the structural response of the stadium and conducted a similar analysis of seismic readings from three other concerts at SoFi Stadium that summer: country music’s Morgan Waller, Beyoncé, and Metallica, as well as picking up clear signals at one monitoring station for the three opening acts: Pantera, DJ Khaled, and Five Finger Death Punch, respectively. The results were markedly similar to the seismic data gathered from the Taylor Swift concerts, although none of the signals matched the strongest of those detected during the Swift concerts.

The researchers were surprised to find that the seismic signals from the Metallica concert were the weakest among all the concerts and markedly different from the others, “slanted and kind of weird looking,” per Tepp. They found several comments in music forums from fans complaining about poor sound quality at the Metallica concert. “If fans had a hard time discerning the song or beat, it may explain the more variable signals because it would have influenced their movements,” the authors wrote.

It’s also possible that heavy metal live performances are less tightly choreographed than Beyoncé or Swift performances, or that heavy metal fans don’t move with the music in quite the same way. “Metal fans like to headbang a lot, so they’re not necessarily bouncing,” said Tepp. “It might just be that the ways in which they move don’t create as strong of a signal.”

Seismological Research Letters, 2024. DOI: 10.1785/0220230385  (About DOIs).

Taylor Swift fans dancing and jumping created last year’s “Swift quakes” Read More »

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SCOTUS mifepristone case: Justices focus on anti-abortion groups’ legal standing

Abortion, alito, barrett, clarence thomas, comstock, drug approval, fda, gorsuch, kagan, ketanji brown jackson, medication abortion, mifepristone, Policy, Science, SCOTUS / /
Demonstrators participate in an abortion-rights rally outside the Supreme Court as the justices of the court hear oral arguments in the case of the <em>US Food and Drug Administration v. Alliance for Hippocratic Medicine</em> on March 26, 2024 in Washington, DC.” src=”https://cdn.arstechnica.net/wp-content/uploads/2024/03/GettyImages-2115237711-800×533.jpeg”></img><figcaption> <p><a data-height=Enlarge / Demonstrators participate in an abortion-rights rally outside the Supreme Court as the justices of the court hear oral arguments in the case of the US Food and Drug Administration v. Alliance for Hippocratic Medicine on March 26, 2024 in Washington, DC.

The US Supreme Court on Tuesday heard arguments in a case seeking to limit access to the abortion and miscarriage drug mifepristone, with a majority of justices expressing skepticism that the anti-abortion groups that brought the case have the legal standing to do so.

The case threatens to dramatically alter access to a drug that has been safely used for decades and, according to the Guttmacher Institute, was used in 63 percent of abortions documented in the health care system in 2023. But, it also has sweeping implications for the Food and Drug Administration’s authority over drugs, marking the first time that courts have second-guessed the agency’s expert scientific analysis and moved to restrict access to an FDA-approved drug.

As such, the case has rattled health experts, reproductive health care advocates, the FDA, and the pharmaceutical industry alike. But, based on the line of questioning in today’s oral arguments, they have reason to breathe a sigh of relief.

Standing

The case was initially filed in 2022 by a group of anti-abortion organizations led by the Alliance for Hippocratic Medicine. They collectively claimed that the FDA’s approval of mifepristone in 2000 was unlawful, as were FDA actions in 2016 and 2021 that eased access to the drug, allowing for it to be prescribed via telemedicine and dispensed through the mail. The anti-abortion groups justified bringing the lawsuit by claiming that the doctors in their ranks are harmed by the FDA’s actions because they are forced to treat girls and women seeking emergency medical care after taking mifepristone and experiencing complications.

The FDA and numerous medical organizations have emphatically noted that mifepristone is extremely safe and the complications the lawsuit references are exceedingly rare. Serious side effects occur in less than 1 percent of patients, and major adverse events, including infection, blood loss, or hospitalization, occur in less than 0.3 percent, according to the American College of Obstetricians and Gynecologists. Deaths are almost non-existent.

Still, a conservative federal judge in Texas sided with the anti-abortion groups last year, revoking the FDA’s 2000 approval. A conservative panel of judges for the Court of Appeals for the 5th Circuit in New Orleans then partially overturned the ruling, undoing the lower court’s ruling on the 2000 approval, allowing the FDA’s approval to stand, but still finding the FDA’s 2016 and 2021 actions unlawful. The ruling was frozen until the Supreme Court weighed in.

Today, many of the Supreme Court Justices went back to the very beginning: the claimed scenario that the plaintiff doctors have been or will imminently be harmed by the FDA’s actions. At the outset of the hearings, Solicitor General Elizabeth Prelogar argued that the plaintiffs had not been harmed, and, even if they were, they already had federal protections and recourse. Any doctor who consciously objects to caring for a patient who has had an abortion already has federal protections that prevent them from being forced to provide that care, Prelogar argued. As such, hospitals have legal obligations and have set up contingency and staffing plans to prevent violating those doctors’ federal conscious objection protections.

SCOTUS mifepristone case: Justices focus on anti-abortion groups’ legal standing Read More »

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Bridge collapses put transportation agencies’ emergency plans to the test

Baltimore, bridges, Cargo ship, Science, syndication, transportation / /
The Dali container vessel after striking the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore on March 26. The commuter bridge collapsed after being struck by a container ship, causing vehicles to plunge into the water and halting shipping traffic at one of the most important ports on the US East Coast.

Enlarge / The Dali container vessel after striking the Francis Scott Key Bridge that collapsed into the Patapsco River in Baltimore on March 26. The commuter bridge collapsed after being struck by a container ship, causing vehicles to plunge into the water and halting shipping traffic at one of the most important ports on the US East Coast.

A container ship rammed into the Francis Scott Key Bridge in Baltimore around 1: 30 am on March 26, 2024, causing a portion of the bridge to collapse into Baltimore Harbor. Officials called the event a mass casualty and were searching for people in the waters of the busy port.

This event occurred less than a year after a portion of Interstate 95 collapsed in north Philadelphia during a truck fire. That disaster was initially expected to snarl traffic for months, but a temporary six-lane roadway was constructed in 12 days to serve motorists while a permanent overpass was rebuilt.

US cities often face similar challenges when routine wear and tear, natural disasters, or major accidents damage roads and bridges. Transportation engineer Lee D. Han explains how planners, transit agencies, and city governments anticipate and manage these disruptions.

How do agencies plan for disruptions like this?

Planning is a central mission for state and metropolitan transportation agencies.

Traditional long-term planning focuses on anticipating and preparing for growing and shifting transportation demand patterns. These changes are driven by regional and national economic and population trends.

Shorter-term planning is about ensuring mobility and safety during service disruptions. These disruption events can include construction, major scheduled events like music festivals, traffic incidents such as crashes and hazardous material spills, emergency evacuations, and events like the bridge collapse in Baltimore.

Agencies have limited resources, so they typically set priorities based on how likely a given scenario is, its potential adverse effects, and the countermeasures that officials have available.

For bridges, the Federal Highway Administration sets standards and requires states to carry out periodic inspections. In addition, agencies develop a detouring plan for each bridge in case of a structural failure or service disruption. In Baltimore, Key Bridge traffic will be routed through two tunnels that pass under the harbor, but trucks carrying hazardous materials will have to take longer detours.

Major bridges, such as those at Mississippi River crossings, are crucial to the nation’s economy and security. They require significant planning, commitment, and coordination between multiple agencies. There usually are multiple contingency plans in place to deal with immediate traffic control, incident response, and field operations during longer-term bridge repair or reconstruction projects.

What are some major challenges of rerouting traffic?

Bridges are potential choke points in highway networks. When a bridge fails, traffic immediately stops and begins to flow elsewhere, even without a formal detouring plan. Transportation agencies need to build or find excess capacity before a bridge fails so that the disrupted traffic has alternative routes.

This is usually manageable in major urban areas that have many parallel routes and bridges and built-in redundancy in their road networks. But for rural areas, failure of a major bridge can mean extra hours or even days of travel.

When traffic has to be rerouted off an interstate highway, it can cause safety and access problems. If large trucks are diverted to local streets that were not designed for such vehicles, they may get stuck on railroad tracks or in spaces too small for them to turn around. Heavy trucks can damage roads and bridges with low weight limits, and tall trucks may be too large to fit through low-clearance underpasses.

Successful rerouting requires a lot of coordination between agencies and jurisdictions. They may have to adjust road signal timing to deal with extra cars and changed traffic patterns. Local drivers may need to be directed away from these alternative routes to prevent major congestion.

It’s also important to communicate with navigation apps like Google Maps and Waze, which every driver has access to. Route choices that speed up individual trips may cause serious congestion if everyone decides to take the same alternate route and it doesn’t have enough capacity to handle the extra traffic.

Bridge collapses put transportation agencies’ emergency plans to the test Read More »

workers-with-job-flexibility-and-security-have-better-mental-health

Workers with job flexibility and security have better mental health

absenteeism, anxiety, health, job flexibility, job security, Mental Health, psychological distress, return-to-office, Science / /

Healthier work —

Job flexibility and security were linked to significantly less psychological distress and anxiety.

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Workers with job flexibility and security have better mental health

Office Space

American workers who have more flexibility and security in their jobs also have better mental health, according to a study of 2021 survey data from over 18,000 nationally representative working Americans.

The study, published Monday in JAMA Network Open, may not be surprising to those who have faced return-to-office mandates and rounds of layoffs amid the pandemic. But, it offers clear data on just how important job flexibility and security are to the health and well-being of workers.

For the study, job flexibility was assessed in terms of ease of adjusting work schedules, advance notice of scheduling changes, and whether schedules were changed by employers often. People who reported greater flexibility in their job had 26 percent lower odds of serious psychological distress, which was measured on a validated, widely used questionnaire that assesses depression, nervousness, hopelessness, and worthlessness, among other forms of distress. Greater job flexibility was also linked to 13 percent lower odds of experiencing daily anxiety, 11 percent lower odds of experiencing weekly anxiety, and 9 percent lower odds of experiencing anxiety a few times a year.

Job security also appeared to be a boon for mental health. Workers were asked how likely they thought that they may lose their job or get laid off in the next 12 months. Those who reported feeling more secure in their positions had 25 percent lower odds of serious psychological distress. Job security was also associated with 27 percent lower odds of experiencing daily anxiety and 21 percent lower odds of experiencing weekly anxiety.

The study, led by Monica Wang of Boston University’s School of Public Health, also looked at how job flexibility and security affected job absenteeism, finding mixed results. Both job flexibility and security were linked to fewer days where workers reported working while they were sick—suggesting that flexibility and security enabled workers to make use of sick leave when they needed it. In line with that finding, more job flexibility led to more days where workers reported being absent due to illness in the three months prior to the survey. Greater job security, on the other hand, led to fewer absences over the previous three and 12 months.

It’s unclear why that would be the case, but the researchers speculated that “Job security may lead to lower work absenteeism due to higher work satisfaction, decreased job-related stress, and financial security,” they wrote.

Overall, the study’s findings indicate “the substantive impact that flexible and secure jobs can have on mental health in the short-term and long-term,” the researchers conclude.

They do note limitations of the study, the main one being that the study identifies associations and can’t determine that job flexibility and security directly caused mental health outcomes and the work absence findings. Still, they suggest that workplace policies could improve the mental health of employees. This includes flexible scheduling, leave policies, and working arrangements, including remote and hybrid options, which can all allow workers to accommodate personal and family needs. For improving job security, the researchers recommend longer-term contracts and long-term strategies to invest in employees, such as “uptraining,” skill development, and advancement opportunities.

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Eternal Sunshine of the Spotless Mind and the philosophy of self, identity, and memory

cognitive neuroscience, Eternal Sunshine of the Spotless Mind, films, memory, personal identity, Science, science of memory, science philosophy / /
<em>Eternal Sunshine of the Spotless Mind</em> stars Jim Carrey in one of his most powerful dramatic roles.” src=”https://cdn.arstechnica.net/wp-content/uploads/2024/03/eternal6-800×514.jpg”></img><figcaption> <p><a data-height=Enlarge / Eternal Sunshine of the Spotless Mind stars Jim Carrey in one of his most powerful dramatic roles.

Focus Features

Last week, the 2004 cult classic Eternal Sunshine of the Spotless Mind marked its 20th anniversary, prompting many people to revisit the surreal sci-fi psychological drama about two ex-lovers who erase their memories of each other—only to find themselves falling in love all over again. Eternal Sunshine was a box office success and earned almost universal praise upon its release. It’s still a critical favorite today and remains one of star Jim Carrey’s most powerful and emotionally resonant dramatic roles. What better time for a rewatch and in-depth discussion of the film’s themes of memory, personal identity, love, and loss?

(Spoilers for the 2004 film below.)

Director Michel Gondry and co-writer Pierre Bismuth first came up with the concept for the film in 1998, based on a conversation Bismuth had with a female friend who, when he asked, said she would absolutely erase her boyfriend from her memory if she could. They brought on Charlie Kaufman to write the script, and the three men went on to win an Oscar for Best Original Screenplay for their efforts. The title alludes to a 1717 poem by Alexander Pope, “Eloisa to Abelard,” based on the tragic love between medieval philosopher Peter Abelard and Héloïse d’Argenteuil and their differing perspectives on what happened between them when they exchanged letters later in life. These are the most relevant lines:

Of all affliction taught a lover yet,

‘Tis sure the hardest science to forget!

…

How happy is the blameless vestal’s lot!

The world forgetting, by the world forgot.

Eternal sunshine of the spotless mind!

Carrey plays Joel, a shy introvert who falls in love with the extroverted free spirit Clementine (Kate Winslet). The film opens with the couple estranged and Joel discovering that Clementine has erased all her memories of him, thanks to the proprietary technology of a company called Lacuna. Joel decides to do the same, and much of the film unfolds backward in time in a nonlinear narrative as Joel (while dreaming) relives his memories of their relationship in reverse. Those memories dissolve as he recalls each one, even though at one point, he changes his mind and tries unsuccessfully to stop the process.

The twist: Joel ends up meeting Clementine all over again on that beach in Montauk, and they are just as drawn to each other as before. When they learn—thanks to the machinations of a vengeful Lacuna employee—what happened between them the first time around, they almost separate again. But Joel convinces Clementine to take another chance, believing their relationship to be worth any future pain.

Joel (Jim Carrey) and Clementine (Kate Winslet) meet-cute on the LIRR to Montauk.

Enlarge / Joel (Jim Carrey) and Clementine (Kate Winslet) meet-cute on the LIRR to Montauk.

Much has been written over the last two decades about the scientific basis for the film, particularly the technology used to erase Joel’s and Clementine’s respective memories. The underlying neuroscience involves what’s known as memory reconsolidation. The brain is constantly processing memories, including associated emotions, both within the hippocampus and across the rest of the brain (system consolidation). Research into reconsolidation of memories emerged in the 2000s, in which past memories (usually traumatic ones) are recalled with the intent of altering them, since memories are unstable during the recall process. For example, in the case of severe PTSD, administering Beta blockers can decouple intense feelings of fear from traumatic memories while leaving those memories intact.

Like all good science fiction, Eternal Sunshine takes that grain of actual science and extends it in thought-provoking ways. In the film, so-called “problem memories” can be recalled individually while the patient is in a dream state and erased completely—uncomfortable feelings and all—as if they were computer files. Any neuroscientist will tell you this is not how memory works. What remains most interesting about Eternal Sunshine‘s premise is its thematic exploration of the persistence and vital importance of human memory.

So we thought it would be intriguing to mark the film’s 20th anniversary by exploring those ideas through the lens of philosophy with the guidance of Johns Hopkins University philosopher Jenann Ismael. Ismael specializes in probing questions of physics, metaphysics, cognition, and theory of mind. Her many publications include The Situated Self (2009), How Physics Makes Us Free (2016), and, most recently, Time: A Very Short Introduction (2021).

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Dogs’ brain activity shows they recognize the names of objects

Behavioral science, Biology, Dogs, Science / /
Wired for science!

Enlarge / Wired for science!

Boglárka Morvai

Needle, a cheerful miniature schnauzer I had as a kid, turned into a ball of unspeakable noise and fury each time she saw a dog called Puma. She hated Puma so much she would go ballistic, barking and growling. Merely whispering the name “Puma” set off the same reaction, as though the sound of it and the idea of the dog it represented were clearly connected deep in Needle’s mind.

A connection between a word and a mental representation of its meaning is called “referential understanding,” and for a very long time, we believed dogs lacked this ability. Now, a study published by a team of Hungarian researchers indicates we might have been wrong.

Practice makes perfect

The idea that dogs couldn’t form associations with language in a referential manner grew out of behavioral studies in which dogs were asked to do a selective fetching task. The canines had a few objects placed in front of them (like a toy or a bone) and then had to fetch the one specifically named by their owner.

“In laboratory conditions, the dogs performed at random, fetching whatever they could grab first, even though their owners claimed they knew the names of the objects,” said Marianna Boros, a researcher at Neuroethology of Communication Lab at Eötvös Loránd University in Budapest, Hungary. “But the problem is when the dogs are not trained for the task, there are hundreds of things that can disturb them. They can be more interested in one specific toy, they may be bored, or they may not understand the task. So many distractions.”

To get around the issue of distractions, her team checked to see if the dogs could understand words passively using EEG brain monitoring. In humans, the EEG reading that is considered a telltale sign of semantic reasoning is the N400 effect.

“The work on the N400 was first published in 1981, and hundreds of studies replicated it since then with different stimuli. Typically, you show images of objects to the subject and say matching or mismatching names. When you measure EEG brain activity, you will see it looks different in match and mismatch scenarios,” explained Lilla Magyari, also a scientist at Neuroethology of Communication Lab and co-author of the study. (It’s called the N400 effect because the peak of this difference appears around 400 milliseconds after an object is presented, Magyari explained.)

The only change the team made to adapt a standard N400 test to dogs was switching the order of stimuli—the words were uttered first, and the matching or mismatching objects were shown second. “Because when they hear the word which activates mental representation of the object, they are expecting to see it. The sound made them more attentive,” said Magyari.

Timing is everything

In the experiment, the dogs started out lying on a mat with EEG gear on their heads in a room with an experimenter or the owner of a different dog. The owner of the dog being tested was separated by a glass pane with controllable opaqueness. “It was important because EEG studies [can] very precisely time the moment of presentation of your stimulus,” said Boros.

Oszkár Dániel Gáti

Sentences spoken by the owners that would get the dogs’ attention—things like “Kun-kun, look! The ball!”—were recorded and played to each dog through a loudspeaker. Then, 2,000 milliseconds after each dog heard the sentence, the pane would turn transparent, and the owner would appear holding a matching or mismatching toy. “Each test lasted for as long as the dog was happy to participate. The moment it started to get up or look away, we just stopped the test, and the dog could leave the mat and we just finished by playing sessions. It was all super dog-friendly,” Boros said.

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Rocket Report: Starship could fly again in May; Ariane 6 coming together

ariane 6, astrobotic, china, european space agency, falcon 9, launch, moon, rocket lab, rocket report, Science, soyuz, Space, spacex, starship / /

Eating their lunch —

“I think we’re really going to focus on getting reentry right.”

–

Nine kerosene-fueled Rutherford engines power Rocket Lab's Electron launch vehicle off the pad at Wallops Island, Virginia, early Thursday.

Enlarge / Nine kerosene-fueled Rutherford engines power Rocket Lab’s Electron launch vehicle off the pad at Wallops Island, Virginia, early Thursday.

Welcome to Edition 6.36 of the Rocket Report! SpaceX wants to launch the next Starship test flight as soon as early May, the company’s president and chief operating officer said this week. The third Starship test flight last week went well enough that the Federal Aviation Administration—yes, the FAA, the target of many SpaceX fans’ frustrations—anticipates a simpler investigation and launch licensing process than SpaceX went through before its previous Starship flights. However, it looks like we’ll have to wait a little longer for Starship to start launching real satellites.

As always, we welcome reader submissions, and if you don’t want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets, as well as a quick look ahead at the next three launches on the calendar.

Starship could threaten small launch providers. Officials from several companies operating or developing small satellite launch vehicles are worried that SpaceX’s giant Starship rocket could have a big impact on their marketability, Space News reports. Starship’s ability to haul more than 100 metric tons of payload mass into low-Earth orbit will be attractive not just for customers with heavy satellites but also for those with smaller spacecraft. Aggregating numerous smallsats on Starship will mean lower prices than dedicated small satellite launch companies can offer and could encourage customers to build larger satellites with cheaper parts, further eroding business opportunities for small launch providers.

Well, yeah … SpaceX’s dedicated rideshare missions are already reshaping the small satellite launch market. The price per kilogram of payload on a Falcon 9 rocket launching a Transporter mission is less than the price per unit on a smaller rocket, like Rocket Lab’s Electron, Firefly’s Alpha, or Europe’s Vega. Companies operating only in the smallsat launch market tout the benefits of their services, often pointing to their ability to deliver payloads into bespoke orbits, rather than dropping off bunches of satellites into more standardized orbits. But the introduction of Orbital Transfer Vehicles for last-mile delivery services has made SpaceX’s Transporter missions, and potentially Starship rideshares, more attractive. “With Starship, OTVs can become the best option for smallsats,” said Marino Fragnito, senior vice president and head of the Vega business unit at Arianespace. If Starship is able to achieve the very low per-kilogram launch prices proposed for it, “then it will be difficult for small launch vehicles,” Fragnito said.

Rocket Lab launches again from Virginia. Rocket Lab’s fourth launch from Wallops Island, Virginia, and the company’s first there in nine months, took off early Thursday with a classified payload for the National Reconnaissance Office, the US government’s spy satellite agency, Space News reports. A two-stage Electron rocket placed the NRO’s payload into low-Earth orbit, and officials declared it a successful mission. The NRO did not disclose any details about the payload, but in a post-launch statement, the agency suggested the mission was conducting technology demonstrations of some kind. “The knowledge gained from this research will advance innovation and enable the development of critical new technology,” said Chris Scolose, director of the NRO.

A steady customer for Rocket Lab … The National Reconnaissance Office has become a regular customer of Rocket Lab. The NRO has historically launched larger spacecraft, such as massive bus-sized spy satellites, but like the Space Force, is beginning to launch larger numbers of small satellites. This mission, designated NROL-123 by the NRO, was the fifth and last mission under a Rapid Acquisition of a Small Rocket (RASR) contract between NRO and Rocket Lab, dating back to 2020. It was also Rocket Lab’s second launch in nine days, following an Electron flight last week from its primary base in New Zealand. Overall, it was the 46th launch of a light-class Electron rocket since it debuted in 2017. Rocket Lab is building a launch pad for its next-generation Neutron rocket at Wallops. (submitted by EllPeaTea)

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Night flight for Astrobotic’s Xodiac. The Xodiac rocket, a small terrestrial vertical takeoff and vertical landing technology testbed, made its first night flight, Astrobotic says in a statement. The liquid-fueled Xodiac is designed for vertical hops and can host prototype sensors and other payloads, particularly instruments in development to assist in precision landings on other worlds. This first tethered night flight of Xodiac in Mojave, California, was in preparation for upcoming flight testing with the NASA TechLeap Prize’s Nighttime Precision Landing Challenge. These flights will begin in April, allowing NASA to test the ability of sensors to map a landing field designed to simulate the Moon’s surface in near-total darkness.

Building on the legacy of Masten … Xodiac has completed more than 160 successful flights, dating back to the vehicle’s original owner, Masten Space Systems. Masten filed for bankruptcy in 2022, and the company was acquired by Astrobotic a couple of months later. Astrobotic’s primary business area is in developing and flying robotic Moon landers, so it has a keen interest in mastering automated landing and navigation technologies like those it is testing with NASA on Xodiac. David Masten, founder of Masten Space Systems, is now chief engineer for Astrobotic’s propulsion and test department. “The teams will demonstrate their systems over the LSPG (Lunar Surface Proving Ground) at night to simulate landing on the Moon during the lunar night or in shadowed craters.” (submitted by Ken the Bin)

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