Home Blog Page 910

A new approach to measuring and understanding multidirectional polarization

0


A cloud of users’ opinions with its center of mass marked with a red square and the main components as arrows with lengths proportional to their explained variances. Credit: Samuel Martín-Gutiérrez

Germany, India, Mexico, and Spain. As multiparty democracies, these countries present a more complex picture of what brings people together—or divides them. Using social media data, a group of researchers proposes a novel approach to measuring polarization in nations with multiple political parties.

Complexity Science Hub scientist Samuel Martín-Gutiérrez and his colleagues developed a model that infers opinions from social networks, and measures the left-right political division, as well as other more nuanced sources of tension. They analyzed Twitter data from the Spanish elections of 2015 and 2019.

“It’s important to understand polarization in our society, and our findings shed new light on how are shaped,” says Martín-Gutiérrez. “Our approach can lead to useful insights when applied to real-world debates happening on social media.”

The findings of the study were recently published online in the journal Chaos, Solitons & Fractals.

Neutral and unbiased

A key characteristic of the model, according to Martín-Gutiérrez, is its neutrality and unbiasedness. “We assumed we didn’t know anything about the [main Spanish] political parties in the study. And our findings demonstrate that a rigid classification of parties into pre-defined dimensions may not paint the most complete and accurate picture.”

Using Twitter data from two elections, Martín-Gutiérrez and his colleagues from the Universidad Politécnica de Madrid tested the proposed approach in practice. First, they explored the Spanish general elections of December 2015. In a second moment, they dissected the Spanish general elections of April 2019.

“In 2015, we had four opinion poles corresponding to the four main political parties: People’s Party (PP), Spanish Socialist Workers’ Party (PSOE), Podemos, and Citizens (Cs). In 2019, we have five opinion poles, with the addition of Vox,” explains Martín-Gutiérrez.

A new approach to measuring and understanding multidirectional polarization
To understand how social polarization occurs in multipolar systems, check out CSH’s visualization: https://vis.csh.ac.at/multipolar-viz/. Credit: Complexity Science Hub

As a first step, the team identified the , and their ideological positions, on Twitter. “The second step was to analyze the listeners, the interesting part of the network, and assign an opinion to a user according to the average opinion of the people they retweet,” says Martín-Gutiérrez.

Since the social spectrum is more complex and colorful than black and white, the researchers determined the same distance between every pair of poles to avoid bias. “In some contexts, it may seem more appropriate to place certain poles close together. For example, in an election certain may be more ideologically aligned with each other than with the rest. However, parties that share ideology also compete for the same electoral base, often leading to even greater antagonism between them,” explain the authors of the study.

New knowledge

According to them, the opinion patterns of both analyses were consistent with the underlying Spanish social reality and could be interpreted taking into account their context. “There is a clear picture of the Spanish political spectrum, and we can see, for instance, where the opinion distribution is most stretched or where the average opinion is located,” says Martín-Gutiérrez.

“Our findings seem to be in line with what we intuitively know about Spanish politics. From this we can start building new knowledge, for instance, about citizens’ perceptions of politics and their behavior.”

An interactive version of the distribution of the 2015 Spanish elections can be found at here.

The approach could be used in a variety of situations to identify the main points of disagreement. It could also be used in countries with two-party systems, such as the US. The primaries, a key part of the American voting system, are an excellent example, points out Martín-Gutiérrez. “There are several candidates in the presidential state primaries. Our model could be helpful in tracking and understanding how party members’ opinions are distributed,” says the CSH researcher.

The proposed method could also assist policymakers in dealing with polarization and healing social rifts. “It could help policymakers devise de-escalation interventions by addressing the issues that cause the strongest tensions,” argue the authors of the study.

Furthermore, it could be used to combat online misinformation spread by bots and trolls. The model could be used to evaluate the influence automated bots have on as compared to real human accounts.

More information:
Samuel Martin-Gutierrez et al, Multipolar social systems: Measuring polarization beyond dichotomous contexts, Chaos, Solitons & Fractals (2023). DOI: 10.1016/j.chaos.2023.113244

Citation:
A new approach to measuring and understanding multidirectional polarization (2023, March 16)
retrieved 28 April 2023
from https://phys.org/news/2023-03-approach-multidirectional-polarization.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Satellite powered by 48 AA batteries and a $20 microprocessor shows a low-cost way to reduce space junk

0


SBUDNIC, a bread-loaf-sized cube satellite with a drag sail made from Kapton polyimide film, designed and built by students at Brown was launched into space last May on a SpaceX rocket. Credit: Marco Cross

Common sense suggests that space missions can only happen with multimillion-dollar budgets, materials built to withstand the unforgiving conditions beyond Earth’s atmosphere, and as a result of work done by highly trained specialists.

But a team of engineering students from Brown University has turned that assumption on its head.

They built a satellite on a shoestring budget and using off-the-shelf supplies available at most hardware stores. They even sent the satellite—which is powered by 48 Energizer AA batteries and a $20 microprocessor popular with robot hobbyists—into space about 10 months ago, hitching a ride on Elon Musk’s SpaceX rocket.

Now, a new analysis of data from Air Force Space Command shows that the satellite not only successfully operated, but could have far-ranging impacts on efforts to cut down on the growing problem of space debris, which poses a potential danger to all current and future space vehicles.

According to NASA, there are now more than 27,000 pieces of what it calls orbital debris or space junk being tracked by the Department of Defense’s global Space Surveillance Network. Orbital debris ranges from any human-made object in Earth’s orbit that no longer serves a useful function, like nonfunctional spacecraft, abandoned launch-stage vehicles, mission-related debris and fragmentation debris. It also includes defunct satellites that remain in orbit sometimes decades after their mission is complete.

That’s a problem, given that most satellites remain in orbit for an average of 25 years or more, said Rick Fleeter, an adjunct associate professor of engineering at Brown. So when his students got a once-in-a-lifetime chance to design and build their own satellite to be launched into space, they decided to engineer a potential solution.

The students added a 3D-printed drag sail made from Kapton polyimide film to the bread-loaf-sized cube satellite they built. Upon deployment at about 520 kilometers—well above the orbit of the International Space Station—the sail popped open like an umbrella and is helping to push the satellite back down to Earth sooner, according to initial data. In fact, the satellite is well below the other small devices that deployed with it. In early March, for instance, the satellite was at about 470 kilometers above the Earth while the other objects were still in orbit at about 500 kilometers or more.

Satellite shows a low-cost way to reduce space junk
The graph shows how much lower SBUDNIC’s orbit, represented by the thick blue line, is compared with other devices deployed with it from late May 2022 to early March 2023. Credit: Brown University

“You can see in the tracking data that we’re visibly below everybody else and accelerating away from them,” Fleeter said. “You can see that our satellite is already descending toward reentry, whereas the others are still in a nice circular orbit higher up.”

The data suggest that the student satellite, called SBUDNIC, will be out of orbit within five years versus the estimated 25 to 27 years the students calculated for it without the drag device.

Fleeter and the Brown students believe that their initial analysis of the publicly available tracking data serves as a proof of concept that this type of sail can be part of an effort to reduce the number of space debris in orbit around Earth. They hope similar sails can be added to other same-sized devices or scaled up to larger projects in the future.

“The theory and physics of how this works has been pretty well accepted,” Fleeter said. “What this mission showed was more about how you realize it—how you build a mechanism that does that, and how you do it so it’s lightweight, small and affordable.”

The project is a result of a collaboration between researchers at Brown’s School of Engineering and the National Research Council of Italy. It is also supported by D-Orbit, AMSAT-Italy, La Sapienza-University of Rome and the NASA Rhode Island Space Grant. The name of the satellite is a play on Sputnik, the first satellite to orbit the Earth, and is also an acronym for the project participants.

This is the second small satellite designed and built by Brown students that’s been sent into orbit in recent years. The previous satellite, EQUiSat, did 14,000 loops around the Earth before ending its mission and burning up upon re-entering the atmosphere at the end of 2020.

SBUDNIC, however, is believed to be the first of its kind that was sent into orbit made almost exclusively from materials not designed for use in space and at such an astronomically low-cost when compared to other objects in orbit. The total cost of the student-designed cube satellite was about $10,000.

“The large complex we hear about in the news are amazing and inspiring, but they also send a message that space is only for those types of specialized initiatives,” Fleeter said. “Here, we’re opening up that possibility to more people… We’re not breaking down all the barriers, but you have to start somewhere.”

Satellite shows a low-cost way to reduce space junk
The Kapton polyimide drag sail, attached to the SBUDNIC satellite, is helping to push the satellite back down to Earth sooner. Credit: Marco Cross

Engineered by students at Brown

The satellite was designed and built in one year by a group of about 40 students—about half from Brown’s School of Engineering with others from fields as diverse as economics, international relations and sculpture. It started in the course ENGN 1760: Design of Space Systems, which Fleeter taught in Spring 2021.

Italian aerospace company D-Orbit approached with an opening for a satellite on the SpaceX Falcon 9 rocket that would launch in one year. Fleeter turned to his students, who had just listened to their first seminars on space systems design and presented them the opportunity.

From there, the race was on.

The students began by conceptualizing and designing the individual subsystems of the satellite, often working with industry advisors who provided feedback and engineering guidance on the feasibility of their proposals. Students then put their plans into action, managing the technical aspects of the satellite along with coordinating the administrative pieces. The continual prototyping, testing and improving required amounted to a herculean effort from students in terms of hours and brain power.

“The Brown Design Workshop is very quiet at 4 a.m., and I’ve been there during that time more times than I can count,” said Marco Cross, who graduated from Brown last year with a master’s degree in biomedical engineering and served as chief engineer for SBUDNIC.

Students purchased materials they needed at local stores and online retail websites. They often had to engineer nifty workarounds to their materials so they could survive in space. The approach often meant coming up with test apparatuses that replicated specific environmental conditions of space, like the high vibration from the rocket launch, Cross said. For instance, the team used reptile heating lamps in a vacuum chamber to test the thermal shield they created to protect the satellite’s electronics from the sun.

To be cleared for launch, the satellite had to pass qualification tests and meet strict rules and regulations that SpaceX and NASA follow. “It is a zero-failure-tolerated environment,” Cross said. “The team never wavered.”

Satellite shows a low-cost way to reduce space junk
Students working on SBUDNIC did the bulk of their building in the Brown Design Workshop. Credit: Marco Cross

The students got the green light after a series of vacuum, thermal and vibration tests. A group then traveled to Cape Canaveral in Florida to deliver SBUDNIC so it could be inserted into D-Orbit’s larger carrier , which was then put onto the SpaceX rocket.

Students said the project helped them think of themselves as creators and innovators, and that experience ingrained in them lessons they’ll use well into the future.

“I went on to use what I learned on this program to intern at Lockheed Martin Space,” said Selia Jindal, a senior at Brown and one of the project leads. “This project truly helped shape how I see the world and has been extremely influential in shaping my undergrad experience. This sentiment is not unique to me. Many team members, like me, came into SBUDNIC with no prior experience in the space industry and left pursuing paths in the field. We have SBUDNIC alumni across the industry—from pursuing Ph.D.s to engineering at SpaceX.”

Along with presenting their findings at conferences and submitting their data to a publication, the SBUDNIC team is currently planning a series of presentations in schools throughout Rhode Island. They hope to inspire future innovators and make high school more aware of the opportunities that exist for them in space engineering and design.

Provided by
Brown University


Citation:
Satellite powered by 48 AA batteries and a $20 microprocessor shows a low-cost way to reduce space junk (2023, March 16)
retrieved 29 April 2023
from https://phys.org/news/2023-03-satellite-powered-aa-batteries-microprocessor.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

‘Terminator zones’ on distant planets could harbor life, astronomers say

0


Some exoplanets have one side permanently facing their star while the other side is in perpetual darkness. The ring-shaped border between these permanent day and night regions is called a “terminator zone.” In a new paper in The Astrophysical Journal, physics and astronomy researchers at UC Irvine say this area has the potential to support extraterrestrial life. Ana Lobo / UCI

In a new study, University of California, Irvine astronomers describe how extraterrestrial life has the potential to exist on distant exoplanets inside a special area called the “terminator zone,” which is a ring on planets that have one side that always faces its star and one side that is always dark.

“These have a permanent day side and a permanent night side,” said Ana Lobo, a postdoctoral researcher in the UCI Department of Physics & Astronomy who led the new work, which just published in The Astrophysical Journal. Lobo added that such planets are particularly common because they exist around stars that make up about 70 percent of the stars seen in the night sky—so-called M-dwarf stars, which are relatively dimmer than our sun.

The terminator is the dividing line between the day and night sides of the planet. Terminator zones could exist in that “just right” temperature zone between too hot and too cold.

“You want a planet that’s in the sweet spot of just the right temperature for having liquid water,” said Lobo, because liquid water, as far as scientists know, is an essential ingredient for life.

On the dark sides of terminator planets, perpetual night would yield plummeting temperatures that could cause any water to be frozen in ice. The side of the planet always facing its star could be too hot for water to remain in the open for long.

“This is a planet where the dayside can be scorching hot, well beyond habitability, and the night side is going to be freezing, potentially covered in ice. You could have large glaciers on the night side,” Lobo said.

Lobo, alongside Aomawa Shields, UCI associate professor of physics & astronomy, modeled the climate of terminator planets using software typically used to model our own planet’s climate, but with a few adjustments, including slowing down planetary rotation.

'Terminator zones' on distant planets could harbor life, astronomers say
Surface temperatures (°C), plotted with the substellar point at the center. The black lines indicate the terminator. Credit: The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/aca970

It’s believed to be the first time astronomers have been able to show that such planets can sustain habitable climates confined to this terminator region. Historically, researchers have mostly studied ocean-covered exoplanets in their search for candidates for habitability. But now that Lobo and her team have shown that terminator planets are also viable refuges for life, it increases the options life-hunting astronomers have to choose from.

“We are trying to draw attention to more water-limited planets, which despite not having widespread oceans, could have lakes or other smaller bodies of liquid water, and these climates could actually be very promising,” Lobo said.

One key to the finding, Lobo added, was pinpointing exactly what kind of terminator zone planet can retain . If the planet is mostly covered in water, then the water facing the star, the team found, would likely evaporate and cover the entire planet in a thick layer of vapor.

But if there’s land, this effect shouldn’t occur.

“Ana has shown if there’s a lot of land on the planet, the scenario we call ‘terminator habitability’ can exist a lot more easily,” said Shields. “These new and exotic habitability states our team is uncovering are no longer the stuff of science fiction—Ana has done the work to show that such states can be climatically stable.”

Recognizing terminator zones as potential harbors for life also means that astronomers will need to adjust the way they study exoplanet climates for signs of life, because the biosignatures life creates may only be present in specific parts of the planet’s atmosphere.

The work will also help inform future efforts by teams using telescopes like the James Webb Space Telescope or the Large Ultraviolet Optical Infrared Surveyor telescope currently in development at NASA as they search for that may host .

“By exploring these exotic climate states, we increase our chances of finding and properly identifying a habitable planet in the near future,” said Lobo.

More information:
Ana H. Lobo et al, Terminator Habitability: The Case for Limited Water Availability on M-dwarf Planets, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/aca970

Citation:
‘Terminator zones’ on distant planets could harbor life, astronomers say (2023, March 16)
retrieved 26 April 2023
from https://phys.org/news/2023-03-terminator-zones-distant-planets-harbor.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Modern glacier remains found near Mars equator suggest water ice possibly present today at low latitudes

0


A Relict Glacier near Mars’ Equator. Credit: NASA MRO HiRISE and CRISM false color composite/Lee et al. 2023

In a groundbreaking announcement at the 54th Lunar and Planetary Science Conference held in The Woodlands, Texas, scientists revealed the discovery of a relict glacier near the equator of Mars. Located in Eastern Noctis Labyrinthus at coordinates 7° 33′ S, 93° 14′ W, this finding is significant as it implies the presence of surface water ice on Mars in recent times, even near the equator. This discovery raises the possibility that ice may still exist at shallow depths in the area, which could have significant implications for future human exploration.

The surface feature identified as a “relict glacier” is one of many light-toned deposits (LTDs) found in the region. Typically, LTDs consist mainly of light-colored sulfate salts, but this deposit also shows many of the features of a glacier, including crevasse fields and moraine bands. The glacier is estimated to be 6 kilometers long and up to 4 kilometers wide, with a surface elevation ranging from +1.3 to +1.7 kilometers. This discovery suggests that Mars’ recent history may have been more watery than previously thought, which could have implications for understanding the planet’s habitability.

“What we’ve found is not ice, but a salt deposit with the detailed morphologic features of a glacier. What we think happened here is that salt formed on top of a glacier while preserving the shape of the ice below, down to details like crevasse fields and moraine bands,” said Dr. Pascal Lee, a planetary scientist with the SETI Institute and the Mars Institute, and the lead author of the study.

The presence of volcanic materials blanketing the region hints of how the sulfate salts might have formed and preserved a glacier’s imprint underneath. When freshly erupted pyroclastic materials (mixtures of volcanic ash, pumice, and hot lava blocks) come in contact with water ice, sulfate salts like the ones commonly making up Mars’s light-toned deposits may form and build up into a hardened, crusty salt layer.

“This region of Mars has a history of volcanic activity. And where some of the volcanic materials came in contact with glacier ice, chemical reactions would have taken place at the boundary between the two to form a hardened layer of sulfate salts,” explains Sourabh Shubham, a graduate student at the University of Maryland’s Department of Geology, and a co-author of the study. “This is the most likely explanation for the hydrated and hydroxylated sulfates we observe in this light-toned deposit.”

Over time, with erosion removing the blanketing volcanic materials, a crusty layer of sulfates mirroring the glacier ice underneath became exposed, which would explain how a salt deposit is now visible, presenting features unique to glaciers such as crevasses and moraine bands.

Modern glacier remains found near Mars equator implies water ice possibly present today at low latitudes
Interpretation of the Relict Glacier‘s features. Credit: Lee et al. 2023

“Glaciers often present distinctive types of features, including marginal, splaying, and tic-tac-toe crevasse fields, and also thrust moraine bands and foliation. We are seeing analogous features in this light-toned deposit, in form, location, and scale. It’s very intriguing,” said John Schutt, a geologist at the Mars Institute, experienced icefield guide in the Arctic and Antarctica, and a co-author of this study.

The glacier’s fine-scale features, its associated sulfate salts deposit, and the overlying volcanic materials are all very sparsely cratered by impacts and must be geologically young, likely Amazonian in age, the latest geologic period which includes modern Mars. “We’ve known about glacial activity on Mars at many locations, including near the in the more distant past. And we’ve known about recent glacial activity on Mars, but so far, only at higher latitudes. A relatively young relict glacier in this location tells us that Mars experienced surface ice in recent times, even near the equator, which is new,” said Lee.

It remains to be seen whether water ice might still be preserved underneath the light-toned deposit or if it has disappeared entirely. “Water ice is, at present, not stable at the very surface of Mars near the equator at these elevations. So, it’s not surprising that we’re not detecting any water ice at the surface. It is possible that all the glacier’s water ice has sublimated away by now. But there’s also a chance that some of it might still be protected at shallow depth under the sulfate salts.”

The study draws an analogy with the ancient ice islands on salt lakebeds, or salars, of the Altiplano in South America. There, old glacier ice has remained protected from melting, evaporation, and sublimation underneath blankets of bright salts. Lee and his co-authors hypothesize a similar situation to explain how sulfate salts on Mars might be able to offer protection to otherwise sublimation-vulnerable ice at low latitudes on the planet.

If there is still water ice preserved at shallow depths at a low latitude on Mars, there would be implications for science and human exploration. “The desire to land humans at a location where they might be able to extract water ice from the ground has been pushing mission planners to consider higher latitude sites. But the latter environments are typically colder and more challenging for humans and robots. If there were equatorial locations where ice might be found at shallow depth, then we’d have the best of both environments: warmer conditions for human exploration and still access to ice,” said Lee.

But Lee cautions that more work still needs to be done: “We now have to determine if and how much might actually be present in this relict glacier, and whether other light-toned deposits might also have, or have had, ice-rich substrates.”

More information:
Pascal Lee et al, A Relict Glacier Near Mars’ Equator: Evidence For Recent Glaciation And Volcanism In Eastern Noctis Labyrinthus (2023)

Provided by
SETI Institute


Citation:
Modern glacier remains found near Mars equator suggest water ice possibly present today at low latitudes (2023, March 15)
retrieved 27 April 2023
from https://phys.org/news/2023-03-modern-glacier-mars-equator-ice.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Future NASA moonwalkers to sport sleeker spacesuits

0


Axiom Space chief engineer Jim Stein demonstrates a prototype spacesuit, Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip

Moonwalking astronauts will have sleeker, more flexible spacesuits that come in different sizes when they step onto the lunar surface later this decade.

Exactly what that looks like remained under wraps. The designing the next-generation spacesuits, Axiom Space, said Wednesday that it plans to have new versions for training purposes for NASA later this summer.

The moonsuits will be white like they were during NASA’s Apollo program more than a half-century ago, according to the company. That’s so they can reflect heat and keep future moonwalkers cool.

The suits will provide greater flexibility and more protection from the moon’s harsh environment, and will come in a wider range of sizes, according to the Houston-based company.

NASA awarded Axiom Space a $228.5 million contract to provide the outfits for the in more than 50 years. The is targeting late 2025 at the earliest to land two astronauts on the moon’s south pole.

  • Future NASA moonwalkers to sport sleeker spacesuits
    Axiom Space chief engineer Jim Stein, left, demonstrates a prototype spacesuit as astronaut Peggy Whitson, right, talks about the new suit, Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip
  • Future NASA moonwalkers to sport sleeker spacesuits
    Axiom Space chief engineer Jim Stein demonstrates a prototype spacesuit, Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip
  • Future NASA moonwalkers to sport sleeker spacesuits
    Axiom Space chief engineer Jim Stein demonstrates a prototype spacesuit, Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip
  • Future NASA moonwalkers to sport sleeker spacesuits
    Axiom Space chief engineer Jim Stein, left, greets children during a demonstration Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip
  • Future NASA moonwalkers to sport sleeker spacesuits
    Axiom Space chief engineer Jim Stein demonstrates a prototype spacesuit, Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip
  • Future NASA moonwalkers to sport sleeker spacesuits
    Axiom Space chief engineer Jim Stein demonstrates a prototype spacesuit, Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip
  • Future NASA moonwalkers to sport sleeker spacesuits
    Axiom Space chief engineer Jim Stein demonstrates a prototype spacesuit, Wednesday, March 15, 2023, in Houston. NASA selected Axiom Space to design the spacesuits that its moonwalking astronauts will wear when they step onto the lunar surface later this decade. Credit: AP Photo/David J. Phillip

At Wednesday’s event in Houston, an Axiom employee modeled a dark spacesuit, doing squats and twisting at the waist to demonstrate its flexibility. The company said the final version will be different, including the color.

“I didn’t want anybody to get that mixed up,” said Axiom’s Russell Ralston.

© 2023 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.

Citation:
Future NASA moonwalkers to sport sleeker spacesuits (2023, March 15)
retrieved 30 April 2023
from https://phys.org/news/2023-03-future-nasa-moonwalkers-sport-sleeker.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Even in small businesses, minimum wage hikes don’t cause job losses, study finds

0


Many small businesses fear that higher minimum wages will force them to lose profits or cut jobs. But new research co-authored at UC Berkeley finds that costs can be passed to customers with little impact on business — and considerable benefit for workers. Credit: Wikimedia Commons

Restaurants, retail stores and other small businesses, long thought to be vulnerable to increases in the minimum wage, generally do not cut jobs and may actually benefit when governments raise minimum pay, according to a new study co-authored at UC Berkeley.

The prevailing wisdom among many and policymakers is that when the rises, smaller low- employers suffer more from higher labor costs and are more likely to cut jobs. But the groundbreaking new study, co-authored by Berkeley economist Michael Reich, found that small businesses can pass the costs on to consumers with little negative impact.

“A minimum wage increase doesn’t kill jobs,” said Reich, chair of UC Berkeley’s Center on Wage and Employment Dynamics (CWED). “It kills job vacancies, not jobs. The higher wage makes it easier to recruit workers and retain them. Turnover rates go down. Other research shows that those workers are likely to be a little more productive, as well.”

The federal minimum wage has been $7.25 an hour since 2009, but California and dozens of state and local governments in recent years have raised their minimum to $15.50 or more.

The new working paper is the first ever to examine the impact of higher minimum wages on small, low-wage businesses, a sector that includes restaurants, grocery and , and child care operations. It’s the second recent study by Reich and co-authors that challenges the conventional wisdom on minimum wages.

A working paper released last fall and revised in December found that $15-an-hour and higher minimum wages in California and other states and cities gave employees more financial security without causing their employers to cut jobs. (An updated version of that paper will be released in coming weeks, Reich said.)

Business groups have long warned that teen workers would be the most likely to lose their jobs when employers confronted higher minimum wages. But Reich and his colleagues found that often allowed teenage employees to work a little less and study more.

The findings have dramatic implications for public policy: Most obviously, higher wages reduce poverty and financial insecurity. But, Reich said, governments currently spend millions of dollars every year on tax breaks for businesses confronted with government-approved minimum wage hikes. Those expenses may be unnecessary, he said.

Conventional business wisdom lags behind research insights

UC Berkeley is globally influential in the field of labor economics and a leading producer of research on the minimum wage in the U.S. and other countries. Reich has written extensively on the topic.

Such research has been repeatedly verified and now is widely accepted in economics. Still, for opponents, it seems only common sense that when employers face higher wage costs, they will employ fewer workers.

“We worked on this new paper because we continually heard that small businesses are especially vulnerable to higher minimum wages,” Reich said in an interview yesterday. “I heard that from a prominent member of the U.S. House of Representatives when I testified at a hearing in 2019. I’ve heard it from the National Federation of Independent Businesses many, many times. For some people it’s a given—but it’s not supported by the evidence.”

Reich’s latest paper, co-authored with Belgian economist Jesse Wursten, carried that inquiry into small, medium and large U.S. businesses that comprise the low-wage economy. Restaurants, grocery stores and general merchandise stores account for 36% of all minimum-wage employment.

The researchers used state-of-the art statistical methods and 30 years of employer-provided data from the U.S. Census to understand how some 550 changes in state and federal minimum wages between 1990 and 2019 played out in the .

It’s counterintuitive, but higher wages benefit almost everyone

When employers hear that minimum wages are going up, Reich explained, they tend to imagine the impact only on their own businesses. They wonder how they can absorb higher costs without cutting staff or losing profit.

“I say to them, ‘Look, your industry will respond very differently compared to what your individual firm can do,'” Reich added. “‘If everyone in the industry faces the same shocks and costs, not just you, then the market response might be a modest price increase.'”

Indeed, some restaurants pass on the higher costs to consumers—and the small price increases are not enough to drive consumers away, Reich said. The owners benefit further because higher wages mean less turnover, as well as less advertising and training for new workers. In the end, their profits are not harmed.

“The net effect,” Reich said, “is a transfer of income from consumers, who are able to pay a bit more, to the workers.”

The authors found that among all businesses and workers studied, higher minimum wages led to lower employment only among high school-age workers in .

But that cuts two ways, Reich said. While employment in that sector fell, teens overall earned more—so they could work less and study more. The study cites other recent research that, among students of low socio-economic status, a 10% increase in the minimum wage reduces the high school dropout rate by about 10%.

Reich’s paper found that the effects are amplified by the growing availability of college financial aid programs that reward high school students for strong academic performance.

So in the market at large, Reich said, there are now more incentives for adolescents to focus on studies.

“Given the many benefits of educational attainment,” the authors write, “the long term impact on teens substituting time studying for time working in the labor market should be considered a benefit, not a cost, of minimum wage policies.”

More information:
Small Businesses and the Minimum Wage: irle.berkeley.edu/publications … nd-the-minimum-wage/

Citation:
Even in small businesses, minimum wage hikes don’t cause job losses, study finds (2023, March 15)
retrieved 28 April 2023
from https://phys.org/news/2023-03-small-businesses-minimum-wage-hikes.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Researcher solves nearly 60-year-old game theory dilemma

0


Credit: Pixabay/CC0 Public Domain

To understand how driverless vehicles can navigate the complexities of the road, researchers often use game theory—mathematical models representing the way rational agents behave strategically to meet their goals.

Dejan Milutinovic, professor of electrical and computer engineering at UC Santa Cruz, has long worked with colleagues on the complex subset of called differential games, which have to do with in motion. One of these games is called the wall pursuit game, a relatively simple model for a situation in which a faster pursuer has the goal to catch a slower evader who is confined to moving along a wall.

Since this game was first described nearly 60 years ago, there has been a dilemma within the game—a set of positions where it was thought that no game optimal solution existed. But now, Milutinovic and his colleagues have proved in a new paper published in the journal IEEE Transactions on Automatic Control that this long-standing dilemma does not actually exist, and introduced a new method of analysis that proves there is always a deterministic solution to the wall pursuit game. This discovery opens the door to resolving other similar challenges that exist within the field of differential games, and enables better reasoning about autonomous systems such as driverless vehicles.

Game theory is used to reason about behavior across a wide range of fields, such as economics, political science, computer science and engineering. Within game theory, the Nash equilibrium is one of the most commonly recognized concepts. The concept was introduced by mathematician John Nash and it defines game optimal strategies for all players in the game to finish the game with the least regret. Any player who chooses not to play their game will end up with more regret, therefore, rational players are all motivated to play their equilibrium strategy.

This concept applies to the wall pursuit game—a classical Nash equilibrium strategy pair for the two players, the pursuer and evader, that describes their best strategy in almost all of their positions. However, there are a set of positions between the pursuer and evader for which the classical analysis fails to yield the game optimal strategies and concludes with the existence of the dilemma. This set of positions are known as a singular surface—and for years, the research community has accepted the dilemma as fact.

But Milutinovic and his co-authors were unwilling to accept this.

“This bothered us because we thought, if the evader knows there is a singular surface, there is a threat that the evader can go to the singular surface and misuse it,” Milutinovic said. “The evader can force you to go to the singular surface where you don’t know how to act optimally—and then we just don’t know what the implication of that would be in much more complicated games.”

So Milutinovic and his co-authors came up with a new way to approach the problem, using a mathematical concept that was not in existence when the wall pursuit game was originally conceived. By using the viscosity solution of the Hamilton–Jacobi–Isaacs equation and introducing a rate of loss analysis for solving the singular surface they were able to find that a game optimal solution can be determined in all circumstances of the game and resolve the dilemma.

The viscosity solution of partial differential equations is a mathematical concept that was non-existent until the 1980s and offers a unique line of reasoning about the solution of the Hamilton-Jacobi-Isaacs equation. It is now well known that the concept is relevant for reasoning about optimal control and game theory problems.

Using viscosity solutions, which are functions, to solve game theory problems involves using calculus to find the derivatives of these functions. It is relatively easy to find game optimal solutions when the viscosity solution associated with a game has well-defined derivatives. This is not the case for the wall-pursuit game, and this lack of well-defined derivatives creates the dilemma.

Typically when a dilemma exists, a is that players randomly choose one of possible actions and accept losses resulting from these decisions. But here lies the catch: if there is a loss, each rational player will want to minimize it.

So to find how players might minimize their losses, the authors analyzed the viscosity solution of the Hamilton-Jacobi-Isaacs equation around the singular surface where the derivatives are not well-defined. Then, they introduced a rate of loss analysis across these singular surface states of the equation. They found that when each actor minimizes its rate of losses, there are well-defined game strategies for their actions on the singular surface.

The authors found that not only does this rate of loss minimization define the game optimal actions for the singular surface, but it is also in agreement with the game optimal actions in every possible state where the classical analysis is also able to find these actions.

“When we take the rate of loss analysis and apply it elsewhere, the game optimal actions from the classical analysis are not impacted ,” Milutinovic said. “We take the classical theory and we augment it with the rate of loss analysis, so a solution exists everywhere. This is an important result showing that the augmentation is not just a fix to find a solution on the singular surface, but a fundamental contribution to game theory.

Milutinovic and his co-authors are interested in exploring other theory problems with singular surfaces where their new method could be applied. The paper is also an open call to the research community to similarly examine other dilemmas.

“Now the question is, what kind of other dilemmas can we solve?” Milutinovic said.

More information:
Dejan Milutinovic et al, Rate of Loss Characterization That Resolves the Dilemma of the Wall Pursuit Game Solution, IEEE Transactions on Automatic Control (2023). DOI: 10.1109/TAC.2021.3137786

Citation:
Researcher solves nearly 60-year-old game theory dilemma (2023, March 14)
retrieved 26 April 2023
from https://phys.org/news/2023-03-year-old-game-theory-dilemma.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Researcher applies evolutionary math to March Madness

0


Stanford women’s basketball has earned a No. 1 seed for the third year in a row in the 2023 NCAA Tournament. The team won the tournament in 2021. Credit: Stanford Athletics / Bob Drebin

March Madness is upon us and with it, the tradition of making tournament brackets. Where most of us see a grid of future travails and triumphs that will determine the NCAA Division I champions, Stanford mathematical geneticist Noah Rosenberg sees something more: evolutionary history.

In 2021, to accommodate COVID-19, the single-elimination tournaments of March Madness, usually nationwide events, were each confined to a single location.

This happened to resemble a problem that Rosenberg had recently taught in his mathematical evolutionary modeling class: What is the number of sequences in which an evolutionary process can produce a particular tree structure with a particular set of relationships among the species? Translated to March Madness, this question becomes: If all the games in a single-elimination sports tournament are played sequentially in the same arena, in how many possible sequences can the games be played?

“The question opens up a new line of thinking,” said Rosenberg, the Stanford Professor in Population Genetics and Society in the School of Humanities and Sciences. “It’s a neat setup where the math of solves the sports problem, and evolutionary biology is in turn aided by the connection to sports.”

Rosenberg and Matthew King, a former undergraduate student, detailed this problem—and the it offers—in a paper available as a pre-print on bioRxiv that that has been accepted for publication in an upcoming issue of Mathematics Magazine.

A shared perspective

Evolutionary biologists are interested in relationships among species, as well as understanding what those relationships can tell us about the evolutionary history that’s given rise to a species. Many features of these histories are possible to estimate from tree diagrams, such as how quickly the species have been diversifying. The study of between organisms is known as phylogenetics and so these tree diagrams are called phylogenetic trees.

It turns out that these paths of biological evolution have lookalikes in many seemingly disparate areas, such as search algorithms in computer science, branching sequences in epidemic transmission, and graph theory in math. By pursuing the similarities between the trees of his evolution research and those of March Madness, Rosenberg saw an opportunity not only to answer a fun question about sports but also to see how that answer would reflect back on evolutionary theory.

“One species can diverge into two and then into two pairs of species, sometimes in one order, and sometimes the order is reversed. But it’s rarely considered that the two pairs split exactly at the same time,” said Rosenberg. “In sports, though, one often does see games scheduled at the same time in tournaments that have multiple arenas available to them. So that makes us think about solving a more unusual evolutionary biology problem where branching events happen at the same time.”

The March Madness-verse

When Rosenberg and King, now a graduate student at Harvard University, finally ran the numbers on a March Madness scenario, the answer surprised them.

“One gets used to how sports tournaments tend to proceed in a very particular way with sequences of ’rounds,” but as we show in the paper, that canonical scheduling choice is chosen from a quite remarkably high number of possibilities,” said Rosenberg.

As it stands now, there are 1,905,458,855,466,636,787,971,925,146,177,334,793,473,753,765,414,856,950,607,419,556,152,726,849,614,067 (or 1.91 x 1078) game sequences possible for one format of the 68-team tournament. If they should ever be confined to a single area, there will still be 360,410,120,625,822,474,490,741,822,944,015,962,624,736,196,480,481,624,064,000,000,000,000 (3.60 x 1068) possibilities.

While the authors enjoyed this thought experiment, computing these numbers wasn’t really the point. Like following a phylogenetic tree, it was about the journey. A problem that started from a class turned into a sports conundrum, led to a new connection, and inspired a mathematical research paper co-authored by a faculty member and an undergraduate.

“Mathematical phylogenetics has a lot of problems that are not hard to state, but that involve serious mathematical thinking that is accessible to undergraduate research,” said Rosenberg. “If people take away anything from it, I hope they think a little about evolutionary trees during their next favorite sporting event.”

More information:
Matthew C. King et al, On a mathematical connection between single-elimination sports tournaments and evolutionary trees, bioRxiv (2022). DOI: 10.1101/2022.08.09.503313

Citation:
Researcher applies evolutionary math to March Madness (2023, March 14)
retrieved 26 April 2023
from https://phys.org/news/2023-03-evolutionary-math-madness.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Study finds ocean currents may affect rotation of Europa’s icy crust

0


Credit: NASA/JPL-Caltech/SwRI/MSSSImage processing: Kevin M. Gill CC BY 3.0

Research reveals a new explanation for how the icy shell of Jupiter’s moon Europa rotates at a different rate than its interior. NASA’s Europa Clipper will take a closer look.

NASA scientists have strong evidence that Jupiter’s moon Europa has an internal under its icy outer —an enormous body of salty water swirling around the moon’s rocky interior. New computer modeling suggests the water may actually be pushing the ice shell along, possibly speeding up and slowing down the rotation of the moon’s icy shell over time.

Scientists have known that Europa’s shell is probably free-floating, rotating at a different rate than the ocean below and the rocky interior. The new modeling is the first to show that Europa’s could be contributing to the rotation of its icy shell.

A key element of the study involved calculating drag—the horizontal force that the moon’s ocean exerts on the ice above it. The research hints at how the power of the ocean flow and its drag against the ice layer could even account for some of the geology seen on Europa’s surface. Cracks and ridges could result from the icy shell slowly stretching and collapsing over time as it is pushed and tugged by the ocean currents.

“Before this, it was known through laboratory experiments and modeling that heating and cooling of Europa’s ocean may drive currents,” said Hamish Hay, a researcher at the University of Oxford and lead author of the study published in the Journal of Geophysical Research: Planets. Hay performed the research while a postdoctoral research associate at NASA’s Jet Propulsion Laboratory in Southern California. “Now our results highlight a coupling between the ocean and the rotation of the icy shell that was never previously considered.”

It might even be possible, using measurements gathered by NASA’s upcoming Europa Clipper mission, to determine with precision how fast the icy shell rotates. When scientists compare images gathered by Europa Clipper with those captured in the past by NASA’s Galileo and Voyager missions, they will be able to examine locations of ice surface features and potentially determine if the position of the moon’s icy shell has changed over time.

For decades, have debated whether Europa’s icy shell might be rotating faster than the deep interior. But rather than tying it to the ocean’s movement, scientists focused on an outside force: Jupiter. They theorized that as the gas giant’s gravity pulls on Europa, it also tugs on the moon’s shell and causes it to spin slightly faster.

“To me, it was completely unexpected that what happens in the ocean’s circulation could be enough to affect the icy shell. That was a huge surprise,” said co-author and Europa Clipper Project Scientist Robert Pappalardo of JPL. “And the idea that the cracks and ridges we see on Europa’s surface could be tied to the circulation of the ocean below—geologists don’t usually think, ‘Maybe it’s the ocean doing that.'”

Europa Clipper, now in its assembly, test, and launch operations phase at JPL, is set to launch in 2024. The spacecraft will begin orbiting Jupiter in 2030, and will use its suite of sophisticated instruments to gather science data as it flies by the moon about 50 times. The mission aims to determine if Europa, with its deep internal ocean, has conditions that could be suitable for life.

Like a pot of water

Using techniques developed to study Earth’s ocean, the paper’s authors relied on NASA supercomputers to make large-scale models of Europa’s ocean. They explored the complexities of how the water circulates, and how heating and cooling affects that movement.

Scientists believe that Europa’s internal ocean is heated from below, due to radioactive decay and tidal heating within the moon’s rocky core. Like water heating in a pot on a stove, Europa’s warm water rises to the top of the ocean.

In the simulations, the circulation initially moved vertically, but the rotation of the moon as a whole caused the flowing water to veer in a more horizontal direction—in east-west and west-east currents. The researchers, by including drag in their simulations, were able to determine that if the currents are fast enough, there could be adequate drag on the ice above to speed up or slow down the shell’s rotation speed. The amount of interior heating—and thus, circulation patterns in the ocean—may change over time, potentially speeding up or slowing rotation of the icy shell above.

“The work could be important in understanding how other ocean worlds’ rotation speeds may have changed over time,” Hay said. “And now that we know about the potential coupling of interior oceans with the surfaces of these bodies, we may learn more about their geological histories as well as Europa’s.”

Europa Clipper’s main science goal is to determine whether there are places below the surface of Jupiter’s icy moon, Europa, that could support life. The mission’s three main science objectives are to understand the nature of the ice shell and the ocean beneath it, along with their composition and geology. The mission’s detailed exploration of Europa will help scientists better understand the astrobiological potential for habitable worlds beyond our planet.

More information:
H. C. F. C. Hay et al, Turbulent Drag at the Ice‐Ocean Interface of Europa in Simulations of Rotating Convection: Implications for Nonsynchronous Rotation of the Ice Shell, Journal of Geophysical Research: Planets (2023). DOI: 10.1029/2022JE007648

Citation:
Study finds ocean currents may affect rotation of Europa’s icy crust (2023, March 14)
retrieved 27 April 2023
from https://phys.org/news/2023-03-ocean-currents-affect-rotation-europa.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

Fake and extremely biased Twitter content decreased between 2016 and 2020, but top influencers were more polarized

0


Change in influencers’ rankings from 2016 to 2020. Influencers ranked in the top 10 in at least one news media category in 2016 or 2020 are shown. The 2016 rankings are displayed to the left of the username or alias, with 2020 rankings listed on the right. For each user only one shift is shown. Its color changes from the user’s highest ranked news media category in 2016 to that in 2020. Each panel shows the change over time between two news media categories. Credit: Nature Human Behaviour (2023). DOI: 10.1038/s41562-023-01550-8

“One side can start the polarization and keep it going forever, but it takes two sides to stop it. That’s why it easily arises, but it’s so difficult to end,” Boleslaw Szymanski said. Szymanski is the Claire & Roland Schmitt Distinguished Professor of Computer Science and director of the Network Science and Technology Center at Rensselaer Polytechnic Institute.

At a time that some describe to be the most deeply polarized in the United States since the Civil War, Szymanski and his research team spent the last two years analyzing vast amounts of Twitter data to examine the social media platform’s influence on U.S. politics. The results are published in the journal Nature Human Behaviour.

The dataset from 2016 contained 171 million tweets sent by 11 million users, and that of 2020 contained 702 million tweets sent by 20 million users. The disparity is because of the platform’s increase in users. Collecting data from two subsequent elections enabled the team to see trends in participation, polarization, and stability of different kinds of influencers, users, and topics. In a broader sense, it revealed the role that the social media platform played in the elections.

The news was both good and bad.

On one hand, the amount of fake and extremely biased content decreased by 2020 compared to 2016, perhaps because of Twitter’s efforts to limit disinformation from going viral. The volume of linking to disinformation websites dropped by half and the number of users sharing fake news dropped even more.

On the other hand, users in 2020 were less likely to share information or interact with users who do not share their than they were in 2016. It created an echo chamber for with the lack of contrary views.

“Even without sending fake news and just propagating selected one-sided facts, influencers can create a mosaic that is not real,” Szymanski said.

Another interesting finding was that a large fraction of top influencers unaffiliated with the media or party organizations in 2020 rose from obscurity, while some influencers affiliated with such organizations joined the extreme bias right and categories.

“Dr. Szymanski’s research comes with a lesson for voters in 2024: check your facts, do your research, and don’t believe everything you read,” said Curt Breneman, dean of the Rensselaer School of Science. “It is also a call to action for and tech executives to ensure that the flames of polarization are not fanned.”

More information:
Hernán Makse, Political polarization of news media and influencers on Twitter in the 2016 and 2020 US presidential elections, Nature Human Behaviour (2023). DOI: 10.1038/s41562-023-01550-8. www.nature.com/articles/s41562-023-01550-8

Citation:
Fake and extremely biased Twitter content decreased between 2016 and 2020, but top influencers were more polarized (2023, March 14)
retrieved 29 April 2023
from https://phys.org/news/2023-03-fake-extremely-biased-twitter-content.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





Source link

netbalaban news