Imaging space debris in high resolution

SOCIETY FOR INDUSTRIAL AND APPLIED MATHEMATICS

Research News

 

IMAGE: FROM LEFT TO RIGHT: SPACE DEBRIS MODELED AS A CLUSTER OF SIX REFLECTIVE OBJECTS, AN IMAGE DEVELOPED OF THE DEBRIS WITHOUT ACCOUNTING FOR THE OBJECTS' ROTATION, AND AN IMAGE DEVELOPED... view more 

CREDIT: FIGURE COURTESY OF MATAN LEIBOVICH, GEORGE PAPANICOLAOU, AND CHRYSOULA TSOGKA.

Litter is not only a problem on Earth. According to NASA, there are currently millions of pieces of space junk in the range of altitudes from 200 to 2,000 kilometers above the Earth's surface, which is known as low Earth orbit (LEO). Most of the junk is comprised of objects created by humans, like pieces of old spacecraft or defunct satellites. This space debris can reach speeds of up to 18,000 miles per hour, posing a major danger to the 2,612 satellites that currently operate at LEO. Without effective tools for tracking space debris, parts of LEO may even become too hazardous for satellites.

In a paper publishing today in the SIAM Journal on Imaging Sciences, Matan Leibovich (New York University), George Papanicolaou (Stanford University), and Chrysoula Tsogka (University of California, Merced) introduce a new method for taking high-resolution images of fast-moving and rotating objects in space, such as satellites or debris in LEO. They created an imaging process that first utilizes a novel algorithm to estimate the speed and angle at which an object in space is rotating, then applies those estimates to develop a high-resolution picture of the target.

Leibovich, Papanicolaou, and Tsogka used a theoretical model of a space imaging system to construct and test their imaging process. The model depicts a piece of fast-moving debris as a cluster of very small, highly reflective objects that represent the strongly reflective edges of an item in orbit, such as the solar panels on a satellite. The cluster of reflectors all move together with the same speed and direction and rotate about a common center. In the model, multiple sources of radiation on the Earth's surface--such as the ground control stations of global navigation satellite systems--emit pulses that are reflected by target pieces of space debris. A distributed set of receivers then detects and records the signals that bounce off the targets.

The model focuses on sources that produce radiation in the X-band, or from frequencies of 8 to 12 gigahertz. "It is well known that resolution can be improved by using higher frequencies, such as the X-band," Tsogka said. "Higher frequencies, however, also result in distortions to the image due to ambient fluctuations from atmospheric effects." Signals are distorted by turbulent air as they travel from the target to receivers, which can make the imaging of objects in LEO quite challenging. The first step of the authors' imaging process was thus to correlate the data taken at different receivers, which can help reduce the effects of these distortions.

The diameter of the area encompassed by the receivers is called the physical aperture of the imaging system -- in the model, this is about 200 kilometers. Under normal imaging conditions, the physical aperture's size determines the resolution of the resulting image; a larger aperture begets a sharper picture. However, the quick movement of the imaging target relative to the receivers can create an inverse synthetic aperture, in which the signals that were detected at multiple receivers as the target moved throughout their field of view are synthesized coherently. This configuration can effectively improve the resolution, as if the imaging system had a wider aperture than the physical one.

Objects in LEO can spin on timescales that range from a full rotation every few seconds to every few hundred seconds, which complicates the imaging process. It is thus important to know--or at least be able to estimate--some details about the rotation before developing the image. The authors therefore needed to estimate the parameters related to the object's rotation before synthesizing the data from different receivers. Though simply checking all of the possible parameters to see which ones yield the sharpest image is technically feasible, doing so would require a lot of computational power. Instead of employing this brute force approach, the authors developed a new algorithm that can analyze the imaging data to estimate the object's rotation speed and the direction of its axis.

After accounting for the rotation, the next step in the authors' imaging process was to analyze the data to develop a picture of the space debris that would hopefully be as accurate and well-resolved as possible. One method that researchers often employ for this type of imaging of fast-moving objects is the single-point migration of cross correlations. Though atmospheric fluctuations do not usually significantly impair this technique, it does not have a very high resolution. A different, commonly-used imaging approach called Kirchhoff migration can achieve a high resolution, as it benefits from the inverse synthetic aperture configuration; however, the trade-off is that it is degraded by atmospheric fluctuations. With the goal of creating an imaging scheme that is not too heavily affected by atmospheric fluctuations but still maintains a high resolution, the authors proposed a third approach: an algorithm whose result they call a rank-1 image. "The introduction of the rank-1 image and its resolution analysis for fast-moving and rotating objects is the most novel part of this study," Leibovich said.

To compare the performance of the three imaging schemes, the authors gave simulated data of a rotating object in LEO to each one and compared the images that they produced. Excitingly, the rank-1 image was much more accurate and well-resolved than the result of single-point migration. It also had similar qualities to the output of the Kirchhoff migration technique. But this result was not entirely surprising, given the problem's configuration. "It is important to note that the rank-1 image benefits from the rotation of the object," Papanicolaou said. Though a rotating object generates more complex data, one can actually incorporate this additional information into the image processing technique to improve its resolution. Rotation at certain angles can also increase the size of the synthetic aperture, which significantly improves the resolution for the Kirchhoff migration and rank-1 images.

Further simulations revealed that the rank-1 image is not easily muddled by errors in the new algorithm for the estimation of rotation parameters. It is also more robust to atmospheric effects than the Kirchhoff migration image. If receivers capture data for a full rotation of the object, the rank-1 image can even achieve optimal imaging resolution. Due to its good performance, this new imaging method could improve the accuracy of imaging LEO satellites and space debris. "Overall, this study shed light on a new method for imaging fast-moving and rotating objects in space," Tsogka said. "This is of great importance for ensuring the safety of the LEO band, which is the backbone of global remote sensing."

###

Source article: Leibovich, M., Papanicolaou, G., & Tsogka, C. (2021). Correlation Based Imaging for Rotating Satellites. SIAM J. Imag. Sci., 14(1), 271-303.

Social dilemma follows 2018 eruption of Kilauea volcano

UNIVERSITY OF HAWAII AT MANOA

Research News

 

IMAGE: FISSURE 8 ERUPTS IN LAVA HAZARD ZONE 1, BACK-LIGHTING A FRONT GATE, A MAILBOX AND UTILITY LINES. MAY 5, 2018. view more 

CREDIT: BRUCE HOUGHTON

The unprecedented cost of the 2018 Kilauea eruption in Hawai'i reflects the intersection of distinct physical and social phenomena: infrequent, highly destructive eruptions, and atypically high population growth, according to a new study published in Nature Communications and led by University of Hawai'i at Mānoa researchers.

It has long been recognized that areas in Puna, Hawai'i, are at high risk from lava flows. This ensured that land values were lower in Puna--which lies within the three highest risk lava hazard zones 1, 2 and 3--which actively promoted rapid population growth.

"Low prices on beautiful land and a scarcity of recent eruptions led to unavoidable consequences--more people and more development," said Bruce Houghton, the lead author of the study and Gordan Macdonald Professor of Volcanology in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). "Ultimately this drastically increased the value of what was at risk in 2018, relative to earlier eruptions of Ki?lauea."

Kilauea is one of the most active volcanoes on Earth and has one of the earliest, most comprehensive volcanic monitoring systems. Its recent history has been dominated by activity at the summit caldera and from one of two lines of vents called the Eastern Rift Zone. Between 1967 and 2018, volcanic activity was dominated by eruptions from the upper part of the Eastern Rift Zone. In contrast, no damaging eruptions occurred after 1961 in the more heavily populated Puna district from the vents within the lower portion of the Eastern Rift Zone.

The UH team assessed trends in population growth in Pāhoa-Kalapana, Hilo and Puna using census data, and compared median cost of land and household income in these areas.

Valuable lessons regarding the complex interplay of science, policy, and public behavior emerged from the 2018 disaster.

"Steep population growth occurred during the absence of any locally sourced eruptions between 1961 and 2018, and set the scene for the unprecedented levels of infra-structural damage during the 2018 Lower Eastern Rift Zone eruption," said Wendy Cockshell, co-author on the paper and technical assistant at the National Disaster Preparedness Training Center (NDPTC) at UH Mānoa.

If population growth resumes in lava hazard zones 1 and 2, there will be increased risk in the most dangerous areas on this exceptionally active volcano translating into high cost of damage in future eruptions.

"Our funded research supports the principle of the initiatives by local and federal government to provide buy-out funding to land owners affected by the 2018 eruption to able them to relocate outside of these hazardous areas," said Houghton.

CAPTION

Within lava hazard zone 1 a new cone is formed and a river of lava flows through properties down into lava hazard zone 2.

CAPTION

Houses may survive but can be surrounded by lava without access to electrical or water supplies. Roads now lead to nowhere. (Note Fissure 8 fountain in the background.)

CREDIT

Bruce Houghton

New sustainable building simulation method points to the future of design

CORNELL UNIVERSITY

Research News

 

ITHACA, N.Y. - A team from Cornell University's Environmental Systems Lab, led by recent graduate Allison Bernett, has put forth a new framework for injecting as much information as possible into the pre-design and early design phases of a project, potentially saving architects and design teams time and money down the road.

"(Our framework) allows designers to understand the full environmental impact of their building," said Bernett, corresponding author of "Sustainability Evaluation for Early Design (SEED) Framework for Energy Use, Embodied Carbon, Cost, and Daylighting Assessment" which published Jan. 10 in the Journal of Building Performance Simulation.

Principle investigators are Timur Dogan, assistant professor of architecture in the College of Architecture, Art and Planning; and Katharina Kral, a licensed architect and lecturer in the Department of Architecture.

"How we look at this is, there's the cost of change in the design process, and then the opportunity of impact," Dogan said. "In the very beginning, changing something doesn't cost anything, but if you're a month into the project, changing something is really expensive, because now you have to rehire consultants and redesign things.

"And then the other thing is the potential of impact," he said. "In the very beginning, just with a simple nudge in the right direction, you can change a project from being an energy hog to something that's very sustainable, and integrates well into the environment."

In 2018, according to the International Energy Agency, the construction sector accounted for 39% of energy and process-related greenhouse gas emissions. That included 11% originating from the manufacturing of building materials and products.

The Sustainability Evaluation for Early Design (SEED) Framework is a decision-making tool that can dynamically and concurrently simulate several variables: building energy performance; embodied carbon (carbon emissions generated by construction and materials); construction cost; and daylighting (the use of natural light to illuminate indoor spaces).

The framework will allow architects and design teams to rapidly trial and rank tens of thousands of design iterations, using as few as four inputs.

Using publicly available data and a suite of available design simulation programs - including Rhino/Grasshopper (a CAD program); ClimateStudio, developed by Dogan, for daylight simulation and building energy modeling; and engineering software Karamba3D - Bernett and the team tested SEED in a case study of a hypothetical mid-sized office building modeled in Boston, Washington, D.C., and Phoenix.

The SEED Framework generated thousands of design options based on variables specific to the three cities in the case study, offering designers the flexibility of many options early in the process, before changing course would get too expensive.

"The idea is, you run this analysis," Dogan said, "and you get a few options that already make a lot of sense, and some options that you can completely forget about. ... [It] always comes down to this lack of information in the decision-making process.

"In that sense, the construction industry is super inefficient," he said. "There's too many players who don't know the full picture and then make decisions that are not always rational. This framework that Allison worked on is geared to help bring the information to the table. Every stakeholder in the design process can then form their own opinion about design goal priorities."

SEED's greatest asset, Bernett said, is amassing a tranche of data on multiple factors in one place, and involving architects early in the design and pre-design phases.

"It takes a lot of time to gather all that data, and we have that prepackaged. So there's definitely a hunger for that," said Bernett, who presented the SEED Framework in September 2019 at the International Building Performance Simulation Conference, in Rome.

"Right now, we rely heavily on energy modelers and consultants to do this work," she said. "And if we can involve architects more readily and more early on, I think that we're going to see a lot of improvement and cost-effectiveness to these early design decisions."

In addition to the publicly available design simulations, the team used AutoFrame, a new procedure developed by Kral for automatically computing structural systems. AutoFrame helps improve the precision of embodied carbon assessments and daylight simulations.

The Cornell Atkinson Center for Sustainability's Small Grants Program provided pivotal support for this work, Bernett said.

"That funding really gave it the push it needed," she said. "It allowed me to present a first iteration [of SEED] at the conference in Rome, and then to really flesh out the research more after that."

###

 

Scientists use Doppler to peer inside cells

Process leads to Scientists use Doppler to peer inside cells, leading to better, faster diagnoses and treatments of infection

PURDUE UNIVERSITY

Research News

 

IMAGE: DAVID NOLTE WORKS WITH THE DOPPLER APPARATUS TO PEER INSIDE LIVING CELLS, GIVING HIM INSIGHT INTO INTRACELLULAR ACTIVITY, METABOLISM, AND PATHOGENICITY view more 

CREDIT: PURDUE UNIVERSITY PHOTO/REBECCA MCELHOE

WEST LAFAYETTE, Ind. -- Doppler radar improves lives by peeking inside air masses to predict the weather. A Purdue University team is using similar technology to look inside living cells, introducing a method to detect pathogens and treat infections in ways that scientists never have before.

In a new study, the team used Doppler to sneak a peek inside cells and track their metabolic activity in real time, without having to wait for cultures to grow. Using this ability, the researchers can test microbes found in food, water, and other environments to see if they are pathogens, or help them identify the right medicine to treat antibiotic-resistant bacteria.

David Nolte, Purdue's Edward M. Purcell Distinguished Professor of Physics and Astronomy; John Turek, professor of basic medical sciences; Eduardo Ximenes, research scientist in the Department of Agricultural and Biological Engineering; and Michael Ladisch, Distinguished Professor of Agricultural and Biological Engineering, adapted this technique from their previous study on cancer cells in a paper released this month in Communications Biology.

Using funding from the National Science Foundation as well as Purdue's Discovery Park Big Idea Challenge, the team worked with immortalized cell lines -- cells that will live forever unless you kill them. They exposed the cells to different known pathogens, in this case salmonella and E. coli. They then used the Doppler effect to spy out how the cells reacted. These living cells are called "sentinels," and observing their reactions is called a biodynamic assay.

"First we did biodynamic imaging applied to cancer, and now we're applying it to other kinds cells," Nolte said. "This research is unique. No one else is doing anything like it. That's why it's so intriguing."

This strategy is broadly applicable when scientists have isolated an unknown microbe and want to know if it is pathogenic -- harmful to living tissues -- or not. Such cells may show up in food supply, water sources or even in recently melted glaciers.

"This directly measures whether a cell is pathogenic," Ladisch said. "If the cells are not pathogenic, the Doppler signal doesn't change. If they are, the Doppler signal changes quite significantly. Then you can use other methods to identify what the pathogen is. This is a quick way to tell friend from foe."

Being able to quickly discern whether a cell is harmful is incredibly helpful in situations where people encounter a living unknown microorganism, allowing scientists to know what precautions to take. Once it is known that a microbe is harmful, they can begin established protocols that allow them to determine the specific identity of the cell and determine an effective antibiotic against the microorganism.

Another benefit is the ability to quickly and directly diagnose which bacteria respond to which antibiotics. Antibiotic resistance can be a devastating problem in hospitals and other environments where individuals with already compromised bodies and immune systems may be exposed to and infected by increasingly high amounts of antibiotic resistant bacteria. Sometimes this results in a potentially fatal condition called bacterial sepsis, or septicemia. This is different from the viral sepsis that has been discussed in connection with COVID-19, though the scientists say their next steps will include investigating viral sepsis.

Treating sepsis is challenging. Giving the patient broad-spectrum antibiotics, which sounds like a good idea, might not help and could make the situation worse for the next patient. Letting bacteria come into close contact with antibiotics that do not kill them only makes them more resistant to that antibiotic and more difficult to fight next time.

Culturing the patient's tissues and homing in on the correct antibiotic to use can take time the patient does not have, usually eight to 10 hours. This new biodynamic process allows scientists to put the patient's bacterial samples in an array of tiny petri dishes containing the tissue sentinels and treat each sample with a different antibiotic. Using Doppler, they can quickly notice which bacterial samples have dramatic metabolic changes. The samples that do are the ones that have reacted to the antibiotic -- the bacteria are dying, being defeated and beaten back by antibiotics.

CAPTION

The team isolated living immortalized cells in multi-well plates to study them with Doppler.

CREDIT

Purdue University photo/Rebecca McElhoe

"When we treat with antibiotics, the bacteria don't have to multiply much before they start to affect the tissue sentinels," Nolte explained. "There are still too few bacteria to see or to measure directly, but they start to affect how the tissues behaves, which we can detect with Doppler."

In less than half the time a traditional culture and diagnosis takes, doctors could tell which antibiotic to administer, bolstering the patient's chances for recovery. The researchers worked closely with the Purdue Research Foundation Office of Technology Commercialization to patent and license their technologies. They plan to further explore whether this method would work for tissue samples exposed to nonliving pathogenic cells or dried spores, and to test for and treat viral sepsis.

CAPTION

The Doppler apparatus allows scientists to observe living cells in real time

CREDIT

Purdue University photo/Rebecca McElhoe

About Purdue University

Purdue University is a top public research institution developing practical solutions to today's toughest challenges. Ranked the No. 5 Most Innovative University in the United States by U.S. News & World Report, Purdue delivers world-changing research and out-of-this-world discovery. Committed to hands-on and online, real-world learning, Purdue offers a transformative education to all. Committed to affordability and accessibility, Purdue has frozen tuition and most fees at 2012-13 levels, enabling more students than ever to graduate debt-free. See how Purdue never stops in the persistent pursuit of the next giant leap at https://purdue.edu/.

ABSTRACT

Doppler imaging detects bacterial infection of living tissue

Honggu Choi, Zhe Li, Zhen Hua, Jessica Zuponcic, Eduardo Ximenes, John J. Turek, Michael R. Ladisch and David D. Nolte

Living 3D in vitro tissue cultures, grown from immortalized cell lines, act as living sentinels as pathogenic bacteria invade the tissue. The infection is reported through changes in the intracellular dynamics of the sentinel cells caused by the disruption of normal cellular function by the infecting bacteria. Here, the Doppler imaging of infected sentinels shows the dynamic characteristics of infections. Invasive Salmonella enterica serovar Enteritidis and Listeria monocytogenes penetrate through multicellular tumor spheroids, while non-invasive strains of Escherichia coli and Listeria innocua remain isolated outside the cells, generating different Doppler signatures. Phase distributions caused by intracellular transport display Lévy statistics, introducing a Lévy-alpha spectroscopy of bacterial invasion. Antibiotic treatment of infected spheroids, monitored through time-dependent Doppler shifts, can distinguish drug-resistant relative to non-resistant strains. This use of intracellular Doppler spectroscopy of living tissue sentinels opens a new class of microbial assay with potential importance for studying the emergence of antibiotic resistance.

Farmers in developing countries can protect both profits and endangered species

RICE UNIVERSITY

Research News

 

HOUSTON - (Feb. 25, 2021) - Low-income livestock farmers in developing countries are often faced with a difficult dilemma: protect their animals from endangered predators, or spare the threatened species at the expense of their livestock and livelihood.

A new paper by Rice University economist Ted Loch-Temzelides examines such circumstances faced by farmers in Pakistan. "Conservation, risk aversion, and livestock insurance: The case of the snow leopard" outlines a plan under which farmers can protect themselves from crippling financial losses while preserving and possibly benefiting from the lives of endangered predators.

"These livestock owners often have very low incomes," Loch-Temzelides said. "The loss of even one animal can be financially devastating. They're faced with the difficult task of weighing conservation efforts against economic losses due to attacks on their herds. And this situation isn't limited to snow leopards -- it applies anywhere large predators live near livestock."

Loch-Temzelides proposes establishing community livestock insurance contracts for farmers in developing countries who don't have access to the types of policies available in more developed nations. Under these contracts, farmers would agree to share the cost of lost animals with other farmers in their community. For example: If one farmer in a community of 10 lost an animal valued at $100, each community member would lose the equivalent of about $10.

By aiding conservation efforts, he added, farmers may stand to reap additional benefits.

"Tourists around the world are willing to pay to see endangered species such as snow leopards in their natural habitats," Loch-Temzelides said. "And revenue from ecotourism can benefit communities and their residents significantly."

While Loch-Temzelides' study focuses on Pakistan, he hopes community livestock insurance can be useful around the world.

###

The study will appear in an upcoming edition of the journal Conservation Letters and is available online at

https://conbio.onlinelibrary.wiley.com/doi/10.1111/conl.12793.

This news release can be found online at news.rice.edu.

Follow Rice News and Media Relations on Twitter @RiceUNews.

Photo link: https://news-network.rice.edu/news/files/2021/02/115314887_l.jpg

Photo credit: 123rf.com

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,978 undergraduates and 3,192 graduate students, Rice's undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 1 for quality of life by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance.

 

Improving water quality could help conserve insectivorous birds -- study

Scarcity of insect prey in disturbed lakes and streams drives decline of birds

FRONTIERS

Research News

 

A new study shows that a widespread decline in abundance of emergent insects - whose immature stages develop in lakes and streams while the adults live on land - can help to explain the alarming decline in abundance and diversity of aerial insectivorous birds (i.e. preying on flying insects) across the USA. In turn, the decline in emergent insects appears to be driven by human disturbance and pollution of water bodies, especially in streams. This study, published in Frontiers in Ecology and Evolution, is one of the first to find evidence for a causal link between the decline of insectivorous birds, the decline of emergent aquatic insects, and poor water quality.

Human activities, such as urbanization and agriculture, have adverse effects on aquatic ecosystems. In the US, 46% of streams are in poor condition, while 57% of lakes suffer from strong human disturbance. The immature stages of aquatic insects, especially stoneflies, mayflies and caddisflies, are known to be highly sensitive to pollution, which is why they have often been used as biomonitors for water quality. But the authors of the present study predicted a priori that emergent insects - whose adult flying stages are important sources of food for birds, spiders, bats and reptiles - should likewise be powerful biomonitors for the health of terrestrial ecosystems. This prediction is borne out by the new results.

"The massive decline in bird fauna across the USA requires that we adopt new paradigms for conservation. Currently, most management and conservation agencies and plans are separated into aquatic and terrestrial divisions. However, aquatic and terrestrial ecosystems are inextricably linked through a suite of ecological connections," says author Dr Maeika Sullivan, associate professor in the School of Environment and Natural Resources and Director of the Schiermeier Olentangy River Wetland Research Park at Ohio State University.

Sullivan and colleagues analyzed data from multiple open-access surveys monitoring water quality, aquatic invertebrates and 21 species of aerial insectivorous birds from the contiguous United States. "The task of putting together these big data sets, collected by different US agencies with different goals and objectives, revealed several new questions and challenges which will require interdisciplinary thinking to resolve," says corresponding author Dr David Manning, assistant professor in the Department of Biology, University of Nebraska at Omaha.

First, the authors show that water quality is a good predictor for local relative abundance of emergent insects. Then they show for the first time that water quality and the associated abundance of emergent insects explains a moderate but significant proportion of the variation in local abundance of aerial insectivorous birds in the US, including both upland and riparian (i.e. foraging on river banks) species.

Not all bird species were equally negatively impacted by declines in the abundance of emergent insects, suggesting that factors such the birds' microhabitat and foraging strategy may also play a role. The western wood pewee (Contopus sordidulus, an upland bird species), the olive-sided flycatcher (C. cooperi, which facultatively lives in riparian zones), and the Acadian flycatcher (Empidonax virescens, which almost exclusively occurs near water) depended most strongly on the local abundance of overall emergent insects. The eastern phoebe (Sayornis phoebe), violet-green swallow (Tachycineta thalassina), tree swallow (Tachycineta bicolor), eastern wood-pewee (C. virens), barn swallow (Hirundo rustica), and chimney swift (Chaetura pelagica), were specifically sensitive to the relative abundance of stoneflies, mayflies and caddisflies.

The authors emphasize the need for interdisciplinary research to develop new conservation and biomonitoring strategies focused on the effects of water quality on endangered birds and other terrestrial wildlife.

"We need a better understanding of the common mechanisms that could drive declines in both aquatic insects and many bird species. We would like to explore some of these shared mechanisms in future research, but at a much larger scale than previously. Tackling these questions will require collaboration among freshwater ecologists, ornithologists, landscape ecologists, entomologists, data scientists, and others," says Manning.

###

OU study highlights need for improving methane emission database

UNIVERSITY OF OKLAHOMA

Research News

 

A University of Oklahoma-led study published in 2020 revealed that both area and plant growth of paddy rice is significantly related to the spatial-temporal dynamics of atmospheric methane concentration in monsoon Asia, where 87% of the world's paddy rice fields are situated. Now, the same international research team has released a follow-up discussion paper in the journal Nature Communications. In this paper, the team identifies the limits and insufficiency of the major greenhouse emission database (EDGAR) in estimating paddy rice methane emissions.

"Methane emission from paddy rice fields contribute to the rising of atmospheric methane concentration (XCH4), one of the greenhouse gases for global warming and climate change," said Xiangming Xiao, a professor in the Department of Microbiology and Plant Biology, College of Arts and Sciences. "In this paper, our team highlighted the needs and pathways to improve this dataset, which could lead to substantial improvement in understanding and modeling methane emission, atmospheric transport and chemistry over monsoon Asia and the globe."

OU researchers developed annual paddy rice maps at 500-meter spatial resolution and quantified the spatial-temporal changes in rice paddy area in monsoon Asia during 2000-2015. Xiao said these annual maps are the first of their kind and could be used to further improve simulations of models that estimate methane emission from paddy rice fields.

Toronto's COVID-19 bike lane expansion boosted access to jobs, retail

A study by University of Toronto Engineering researchers found Toronto's temporary cycling infrastructure increased low-stress road access to jobs and food stores by between 10 and 20 per cent, and access to parks by 6.3 per cent.

UNIVERSITY OF TORONTO FACULTY OF APPLIED SCIENCE & ENGINEERING

Research News

 

IMAGE: A MAP OF TORONTO'S BIKEWAY NETWORK WITH COLOURS REPRESENTING THE ROUTE'S LEVEL OF STRESS. view more 

CREDIT: IMAGE COURTESY OF BO LIN / UNIVERSITY OF TORONTO ENGINEERING

With COVID-19 making it vital for people to keep their distance from one another, the city of Toronto undertook the largest one-year expansion of its cycling network in 2020, adding about 25 kilometres of temporary bikeways.

Yet, the benefits of helping people get around on two wheels go far beyond facilitating physical distancing, according to a recent study by three University of Toronto researchers that was published in the journal Transport Findings.

University of Toronto Engineering PhD candidate Bo Lin, as well as professors Shoshanna Saxe and Timothy Chan used city and survey data to map Toronto's entire cycling network - including the new routes - and found that additional bike infrastructure increased low-stress road access to jobs and food stores by between 10 and 20 per cent, while boosting access to parks by an average of 6.3 per cent.

"What surprised me the most was how big an impact we found from what was just built last summer," says Saxe, an assistant professor in the department of civil and mineral engineering.

"We found sometimes increases in access to 100,000 jobs or a 20 per cent increase. That's massive."

The impact of bikeways added during COVID-19 were greatest in areas of the city where the new lanes were grafted onto an existing cycling network near a large concentration of stores and jobs, such as the downtown core. Although there were new routes installed to the north and east of the city, "these areas remain early on the S-Curve of accessibility given the limited links with pre-existing cycling infrastructure," the study says.

In these areas, the new infrastructure can be the beginning of a future network as each new lane multiplies the impact of ones already built, Saxe says.

As for the study's findings about increasing access to jobs, Saxe says they are not only a measure of access to employment but also a proxy for places you would want to travel to: restaurants, movie theatres, music venues and so on.

The researchers used information from Open Data Toronto and the Transportation Tomorrow 2016 survey, among other sources. Where there were discrepancies, Lin, a PhD student and the study's lead author, gathered the data himself by navigating the city's streets (as a bonus, it helped him get to know Toronto after moving here from Waterloo, Ont.).

"There were some days I did nothing but go around the city using Google Maps," he says.

For Lin, the research has opened up new avenues of investigation into cycling networks, including how bottlenecks can have a ripple effect through the system.

The study, like some of Saxe's past work on cycling routes, makes a distinction between low- and high-stress bikeways to get a more accurate reading of how they affect access to opportunities. At the lowest end of the scale are roads where a child could cycle safely; on the other end are busy thoroughfares for "strong and fearless cyclists" - Avenue Road north of Bloor Street, for example.

"It's legal to cycle on most roads, but too many roads feel very uncomfortable to bike on," Saxe says.

For Saxe, the impact of the new cycling routes shows how a little bike infrastructure can go a long way.

"Think about how long it would have taken us to build 20 kilometres of a metro project - and we need to do these big, long projects - but we also have to do short-term, fast, effective things."

Chan, a professor of industrial engineering in the department of mechanical and industrial engineering, says the tools they used to measure the impact of the new bikeways in Toronto will be useful in evaluating future expansions of the network, as well as those found in other cities.

"You hear lots of debates about bike lanes that are based on anecdotal evidence," he says. "But here we have a quantitative framework that we can use to rigorously evaluate and compare different cycling infrastructure projects.

"What gets me excited is that, using these tools, we can generate insights that can influence decision-making."

The University of Toronto team's research, which was supported by funding from the City of Toronto, may come in handy sooner rather than later. Toronto's city council is slated to review the COVID-19 cycling infrastructure this year.

###

New research shows unpredictable work schedules impact restaurant revenue

Nearly a 5% drop in checks handled by servers asked to stay longer

INSTITUTE FOR OPERATIONS RESEARCH AND THE MANAGEMENT SCIENCES

Research News

 

INFORMS Journal Management Science Study Key Takeaways:

• Changing an employee's hours during their shift, typically by having them stay longer, hurts restaurant revenue.
• Checks for parties handled by servers who'd been asked to stay longer during their shift dropped by 4.4%, on average.
• Servers asked to stay longer reduced the effort spent on upselling and cross-selling additional menu items.

CATONSVILLE, MD, February 25, 2021 - Short notice versus no advance notice makes a huge difference when it comes to employee scheduling in the restaurant industry. New research in the INFORMS journal Management Science finds checks for parties handled by servers who were asked (with no advance notice) to stay longer than their scheduled shift dropped by 4.4%, on average.

The study, "Call to Duty: Just-in-Time Scheduling in a Restaurant Chain," conducted by Masoud Kamalahmadi of the University of Miami, Qiuping Yu of the Georgia Institute of Technology, and Yong-Pin Zhou of the University of Washington analyzed 1.5 million transactions from 25 restaurants in 2016 to look at the impact that unpredictable work schedules have on server sales efforts and restaurant revenue.

The research finds giving an employee a couple of days' notice (short-notice scheduling) doesn't affect sales efforts, however, real-time scheduling (changing people's hours during their shift, typically by having them stay longer) hurts revenue.

"Our analysis indicates that this occurred because servers reduced the effort spent on upselling and cross-selling additional menu items," said Kamalahmadi, an assistant professor of management science. Employee fatigue is controlled for in the study.

"We also show that the reduction in server's sales effort is more profound among less-skilled workers, during the weekend or non-rush hours," continued Yu, an assistant professor of operations management and business analytics at the Scheller College of Business at Georgia Tech.

The researchers found that stepping away from the heavy use of real-time schedules not only creates more predictable work schedules, but also improves the expected profit by up to 1%.

###

About INFORMS and Management Science

Management Science is a premier peer-reviewed scholarly journal focused on research using quantitative approaches to study all aspects of management in companies and organizations. It is published by INFORMS, the leading international association for operations research and analytics professionals. More information is available at http://www.informs.org or @informs.

European unions' support varies for precarious workers

CORNELL UNIVERSITY

Research News

 

ITHACA, N.Y. - In many cases, unions in Europe have helped nonunionized workers whose jobs are precarious, according to new Cornell University research.

In "Dualism or Solidarity? Conditions for Union Success in Regulating Precarious Work," published in December in the European Journal of Industrial Relations, the researchers surveyed academic articles to see how often they would find evidence of unions helping nonunionized workers or helping only their own members, and which conditions were associated with each outcome.

The paper was co-authored by Laura Carver, M.S. 20, and Virginia Doellgast, associate professor of international and comparative labor in the ILR School.

Unions respond to growing worker insecurity in different ways, Carver said.

In some cases, unions work with management to protect their own members while allowing management to cut pay or otherwise increase insecurity for nonunionized workers, she said. This is called dualism, because it creates a dual labor market where unionized insiders are still paid relatively well and have some job security, and nonunionized outsiders are subjected to increasing insecurity.

Unions also can act in solidarity with nonunion workers by proactively extending union protections and increasing security for precarious workers. Examples of union support include the Unite union support of the "Justice for Cleaners" protests in the United Kingdom and support by the French union CGT for the "sans papiers" movement for undocumented immigrant workers in France.

A third union response is described as "failed solidarity" by Carver and Doellgast.

"Unions' attempts at inclusivity are not always successful - in other words, attempts to stand in solidarity with nonunion workers sometimes do not actually reduce their experiences of precarity," Carver said.

After surveying 56 case study-based articles published between 2008 and 2019, they found that:

• In 46% of cases, solidarity was practiced when unions improved working conditions for the peripheral workforce. This includes cases in which the union simultaneously improved conditions for the core workforce, as well as those in which the conditions for the core workforce remained stable or even declined.
• In 26% of cases, the unions practiced dualism by maintaining or improving working conditions for the core, unionized workforce, with either no attempt to address precarity for peripheral workers or increased precarity for these workers.
• In 12% of the cases, solidarity failed - there was no reduction in precarity in spite of union attempts to regulate or improve conditions for peripheral workers.
• In 16% of cases, there were no clear outcomes of dualism, solidarity or failed solidarity.

"The fact that successful solidarity was the most common outcome is notable," Carver said. "This suggests there is cause for optimism, or that increased precarity is not the inevitable outcome."

###

Disclaimer: AAAS and EurekAlert! are not responsible for the accu