Study explores how characteristics of communications networks affect development of shared social identity, group performance

Density, centralization play roles in dynamic of groups’ work

Carnegie Mellon University

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Research has predominantly analyzed the formation of social identity as driven by members belonging to the same categories based on prominent characteristics, such as gender, race, or ethnicity. Less common are studies on recognizing similarity within groups as the basis for forming shared social identities.

In a new study, researchers explored how the characteristics of communication networks in groups (i.e., density and centralization) affected the development of shared social identity and, as a result, group performance. The study’s findings can help managers and other business leaders develop strategies to enhance the performance of their teams.

The study, by researchers at Carnegie Mellon University and the University of Massachusetts Dartmouth, appears in Small Group Research.

“We argue that the structure of a group’s communication network affects a group’s performance, not only by influencing how the group exchanges information, but also by altering the psychological processes of its members, namely the extent to which they share a social identity,” explains Linda Argote, Professor of Organizational Behavior and Theory at Carnegie Mellon’s Tepper School of Business, who coauthored the study. Groups whose members share a social identity are likely to share knowledge and collaborate, which typically results in better performance.

In the business world, much work gets done by groups and communication is required to coordinate the interdependent activities of group members. In this study, researchers sought to determine whether and how communication networks affect the extent to which members share a social identity.

In their work, the researchers theorized that two dimensions of a group’s communication network—density (the ratio of ties among group members to the number of possible ties) and centralization (the extent to which communication ties are concentrated in one or a few members)—interact to affect the extent to which group members share an identity. They manipulated the density and centralization of communication networks in a lab experiment.

In their experiment, 66 groups of four participants worked together on a software development task, communicating in different communication networks. Participants were recruited through a public pool at a mid-Atlantic U.S. university.

Density had a more positive effect on a shared social identity and group performance when networks were less centralized, which led to more similar patterns of connections among members, than when networks were more centralized, the study found. Shared social identity mediated or accounted for the effect of the network on group performance.

Based on these findings, the study’s authors suggest that groups with networks that lead to more differences in members’ links to each other have lower shared social identity and harms its performance. Thus, simply increasing the number of communication ties within a group may not help boost performance if the additional ties increase differences between members. As a result, a leader may need to be aware of a group’s existing structure when encouraging more interaction or participation.

“Our findings can help group leaders and managers be better equipped to improve group performance,” says Brandy Aven, Associate Professor of Organizational Theory, Strategy, and Entrepreneurship at Carnegie Mellon’s Tepper School of Business, who coauthored the study.

Among the study’s limitations, the authors note that their results are more likely to generalize to groups completing interdependent tasks and to small groups where members accurately perceive their communication networks.

“Our work advances understanding of how networks can have psychological effects on groups and demonstrates that sometimes more network ties can tear a team further apart,” adds Jonathan Kush, Associate Professor of Management at the University of Massachusetts Dartmouth’s Charlton College of Business, who led the study. Kush received his Ph.D. in Organizational Behavior and Theory from the Tepper School.

The study was funded by the National Science Foundation and the Center for Organizational Learning, Innovation, and Knowledge at Carnegie Mellon’s Tepper School.

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Journal

Small Group Research

DOI

10.1177/10464964251326615 

Article Title

The Effects of Communication Networks on Shared Social Identity and Group Performance

Article Publication Date

24-Mar-2025

 

Unlocking the genetic secrets of olive tree flowering: a key to climate adaptation

Nanjing Agricultural University The Academy of Science

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Projection of the 318 genotypes from WOGBM on the first two principal components (PC) of a PC analysis based on 235 825 SNPs.

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Credit: Horticulture Research

A recent study has unveiled the genetic blueprint behind flowering time in olive trees, a crucial trait for fruit production that is increasingly under threat from climate change. By analyzing 318 olive genotypes from across the Mediterranean, researchers identified key genetic loci governing flowering time, shedding light on the complex polygenic control of this trait. These findings not only deepen our understanding of olive tree adaptation but also offer new genetic insights to guide breeding programs in developing climate-resilient olive cultivars.

As a cornerstone of Mediterranean agriculture, olive trees are highly sensitive to temperature shifts, which can significantly alter their flowering patterns. Warmer winters may delay flowering, while unseasonably warm springs can trigger premature blooming, increasing the risk of frost damage and disrupting pollination cycles. With climate change amplifying these challenges, olive production—and the livelihoods of millions who depend on it—faces growing uncertainty. Understanding the genetic basis of flowering time has therefore become a scientific imperative for ensuring the future stability of olive cultivation.

Published (DOI: 10.1093/hr/uhae265) on September 24, 2024, in Horticulture Research, a new study led by researchers from the University of Montpellier and CIRAD, France, in collaboration with Moroccan institutions, has mapped the genetic determinants of flowering time in olive trees. Using genome-wide association studies (GWAS) on 318 diverse olive genotypes, the team pinpointed three significant loci associated with flowering time, paving the way for breeding strategies aimed at improving climate adaptability in olive trees.

The research focused on the full flowering date (FFD), a critical phenological stage closely tied to temperature fluctuations. Leveraging capture sequencing, scientists analyzed genetic data from the Worldwide Olive Germplasm Bank of Marrakech, Morocco, uncovering three robust genetic loci on chromosomes 01 and 04 that account for 7.1%, 6.2%, and 6.5% of flowering time variance, respectively. Despite their modest individual effects, these loci suggest a polygenic regulation of flowering, aligning with similar findings in other perennial fruit crops.

The study further emphasized the power of genomic prediction models, revealing that Ridge Regression (RR) outperformed LASSO in predicting flowering times, reinforcing the polygenic nature of the trait. Additionally, researchers identified three distinct genetic clusters within the olive germplasm, corresponding to eastern, central, and western Mediterranean regions, each exhibiting unique flowering behaviors. This geographical genetic structure provides a crucial framework for targeted breeding efforts.

"Our findings highlight the intricate genetic control of flowering time in olive trees and underscore the potential of genomic tools in breeding for climate adaptation," said Dr. Bouchab Khadari, a leading researcher on the study. "This research marks an important step toward developing olive varieties that can withstand the challenges of a shifting climate."

By pinpointing key genetic loci and deciphering their effects, this study provides a critical foundation for breeding programs aimed at optimizing flowering dates in olive trees. Such advancements could help mitigate the risk of frost damage, enhance pollination synchronization, and ultimately strengthen the resilience of olive cultivation in the face of global warming. Beyond securing olive yields, these insights support the long-term sustainability of Mediterranean agriculture—an industry vital not only to regional economies but also to global food security.

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References

DOI

10.1093/hr/uhae265

Original Source URL

https://doi.org/10.1093/hr/uhae265

Funding information

L.A. was funded by an IOC scholarship (N° 2021-03- PhD GRANT). This study was funded through Labex AGRO 2011 – LABX-002, project n° 2003-001 (under I-Site Muse framework) coordinated by Agropolis Foundation.

About Horticulture Research

Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.

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Journal

Horticulture Research

DOI

10.1093/hr/uhae265 

Subject of Research

Not applicable

Article Title

Genome-wide association analysis of flowering date in a collection of cultivated olive tree

Population monitoring of the olive fly is updated with a more efficient method

University of Córdoba

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Researchers who carried out the study

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Credit: Universidad de Córdoba

Smaller and better-distributed yellow adhesive traps allow for better control of the olive fly population, according to a field study carried out by the University of Córdoba

The olive fly is one of the main pests threatening the quality and viability of olive oil in the region. Due to the damage it does, decreasing the weight and quantity of the fruit, and the increasing the acidity of the oil, growers have been "hunting" this insect for decades. Through Integrated Pest Management (IPM), damage control is sought with a reduction in the use of chemically synthesized insecticides. To do this, the first step is to monitor the population to determine the best time to carry out control actions.

The problem is that "the current population monitoring system for the olive fly is obsolete and has no scientific basis," explains researcher Meelad Yousef, who, together with the team formed by Enrique Quesada, Flora Moreno, and Pablo Valverde, with the Agricultural Entomology Group at the University of Córdoba, has carried out a study identifying the most effective method to monitor the olive fly.

After two years of field trials in the provinces of Córdoba and Cádiz, the team managed to determine that small double-sided yellow adhesive panels (10 × 25 cm) are the most efficient traps to gauge olive fly numbers. The ideal distribution, according to the tests, is 15 adhesive panels per hectare, for greater accuracy, but it was also concluded that 4 traps per hectare allow for an effective estimation of the population. This would make it possible to update, with scientific evidence, Spain's Integrated Pest Management Guide, which established 6 traps for a reference plot of 300 hectares, and did not stipulate the best trap for this insect.

"Among the traps studied (6 different ones), the yellow adhesive panels and the McPhail traps (very common for this purpose) outperformed the rest in terms of flies captured, but we selected the yellow adhesive panels because the McPhail traps also captured many natural enemies, in addition to the fly," Meelad Yousef explains. Once the type of trap was selected, they tried different colors: yellow, green, white and blue. The flies were more attracted to the yellow one.

In terms of size, contrary to what one might assume, the smaller trap (10x25cm) was actually more effective than the larger one (20x25); though  it captured the same numbers of flies, but fewer beneficial insects. Size-related information is also absent from the current guide.

In addition, researcher Flora Moreno continued, "we proposed the distribution of traps, and the optimal distance between them to obtain the data allowing us to decide precisely when to treat the crops, reducing costs by not applying treatments at the wrong times."

Variety matters

This work is pioneering in that it relates the damage caused by the olive fly to its populations and the variety of olive tree in question. It was found that the variety of tree is a key factor to predict what damage a certain population will do "because 10 flies do not affect the different varieties in the same way." For example, with a similar number of flies on the Frantoio and Empeltre varieties, the latter suffered greater damage.

This work lays the foundations for more effective monitoring, in turn leading to better decision-making regarding the control of the olive fly, and is key to the development of electronic traps that will send data in real time to growers and technicians, a technology that the Agricultural Entomology group is currently working on.

Reference:

Flora Moreno-Alcaide, Enrique Quesada-Moraga, Pablo Valverde-García, Meelad Yousef-Yousef, Optimizing decision-making potential, cost, and environmental impact of traps for monitoring olive fruit fly Bactroceraoleae (Rossi) (Diptera: Tephritidae), Journal of Economic Entomology, Volume 118, Issue 1, February 2025, Pages 219–228, https://doi.org/10.1093/jee/toae296

 

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Journal

Journal of Economic Entomology

DOI

10.1093/jee/toae296 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Optimizing decision-making potential, cost, and environmental impact of traps for monitoring olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae)

 

Study documents impacts of large-scale entry of rooftop solar panels on competition

Researchers developed dynamic framework to measure market power in wholesale electricity markets

Carnegie Mellon University

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Fossil-fuel plants are increasingly being forced to stop and start production in response to changes in output from renewables. In a new study, researchers developed a dynamic competitive benchmark that accounts for start-up costs and other unit-level operating constraints.  They apply their framework to Western Australia, a setting where rooftop solar capacity more than doubled between 2014 to 2018 to world-leading rooftop solar penetration rates.  The study found that the large-scale expansion of rooftop solar capacity can lead to increases in the collective profitability of fossil fuel plants because competition softens at sunset—plants displaced by solar during the day must incur start-up costs to compete in the evening.  

The study, by researchers at Carnegie Mellon University and Monash University, is published in American Economic Review.

“We developed a framework to measure market power in wholesale electricity markets,” explains Akshaya Jha, associate professor of economics and public policy at Carnegie Mellon’s Heinz College, who co-authored the study. “This framework accounts for features of generating unit technology such as fixed start-up costs and ramping constraints that are becoming increasingly relevant in light of the global transition to intermittent wind and solar technologies.”

Firms that incur the fixed costs required to start production expect to recover these costs by earning revenues in excess of their variable costs in subsequent periods. This presents two challenges for studying competition: First, market power is usually measured based on the markup in prices above short-run marginal cost, but economists have long recognized that setting prices equal to short-run marginal cost ignores the requirement that prices must be sufficient for firms to recover their fixed costs. Second, fixed costs are a barrier to competition: Decisions on the extensive margin to incur the fixed costs necessary to produce affect the intensity of later competition.

Researchers applied their framework to Western Australia, a world leader in rooftop solar penetration rates. They measured market power by comparing observed plant output and market prices to their benchmark—a counterfactual time series of plant output and market prices—that accounts for the recovery of the fixed costs required for plants to start up.

Specifically, they extended static production function approaches by using high-frequency data on input gas use and output electricity to estimate unit-level cost functions with three components: variable costs, start-up costs, and the costs associated with running not tied to output levels. Then, their dynamic benchmark sets output levels to minimize the daily total costs of dispatching power plants to satisfy demand in each half hour of the day while setting prices that allow each plant to recover their fixed and variable costs.

Using this framework, they found that increases in rooftop solar penetration corresponded to sizable increases in the market power rents earned collectively by the fossil fuel fleet after the sun set. Since retail prices paid by electricity users were set via cost-of-service regulation, increases in market power rents largely constituted transfers from retail electricity consumers to producers.

Although rooftop solar penetration had a small effect on efficiency in the wholesale market, the external welfare gains associated with reductions in greenhouse gases are not captured within the wholesale electricity market. In Western Australia, increases in rooftop solar penetration corresponded to substantial declines in the carbon emissions that contribute to climate change, with sizable drops in gas-fired electricity output and thus daytime carbon emissions and only small increases in carbon emissions in the evening associated with solar-induced increases in starts by gas units.

“Our findings speak to the growing relevance of adopting several design features not present in most markets outside the United States,” says Gordon Leslie, senior lecturer in economics at Monash University, who coauthored the study. Among those features:

• Allowing suppliers to submit start-up bids in addition to energy supply curves can allow for co-optimization across hours. This can improve market efficiency, especially as more units stop and start production in response to output from intermittent wind and solar resources.
• Previous research has documented that the benefits of allowing financial participation in the day-ahead market are especially large in contexts where physical operating constraints are more likely to bind and market participants have significant market power. This study showed that increasing rooftop solar penetration rates can exacerbate unit-level start costs and physical operating constraints, resulting in suppliers having greater ability to exercise market power in the evening.
• Worldwide, most electricity users face retail prices that do not vary contemporaneously with wholesale prices and often not even by hour of day. Allowing retail prices to reflect hourly variation in wholesale prices will likely shift some demand from evening to day. As a result, fewer fossil fuel units will need to start up in the late afternoon to compete effectively at sunset. This can reduce firms’ ability to exercise market power during evening peak demand hours, leading to lower wholesale prices and declines in the retail prices paid by consumers.

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Journal

American Economic Review

TWO

10.1257/aer.20211145 

Article Title

Start-up Costs and Market Power: Lessons from the Renewable Energy Transition

Seven leading research universities collaborate to advance solar arrays over California’s canals

The California Solar Canal Initiative will engage the public and private sectors to identify optimal locations to generate renewable energy, save water and conserve land statewide.

University of Southern California

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Artist’s rendition of Project Nexus wide span site — the state’s first solar canal pilot — under construction in California’s Central Valley with Turlock Irrigation District. Credit: Solar AquaGrid

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Credit: Solar AquaGrid

A groundbreaking initiative led by faculty from seven top research universities — six of which are in California — aims to accelerate the deployment of solar arrays over the state’s extensive canal network.

According to a 2021 University of California, Merced, study published in Nature Sustainability, covering large sections of the state’s 4,000 miles of canals with arrays of solar panels could help conserve water, reduce air pollution, save land and generate clean energy using existing land and infrastructure.

The California Solar Canal Initiative (CSCI) research project aims to accelerate the deployment of solar canals across the state by equipping government agencies, utilities, community members and other interested parties with data on optimal locations and identifying willing host communities.

Led by the University of Southern California (USC) Dornsife Public Exchange and independent advisory Solar AquaGrid, CSCI researchers will closely collaborate with the state agencies responsible for water, land and energy: California Department of Water Resources (DWR), California Natural Resources Agency (CNRA) and California Energy Commission (CEC).

“California is leading the way in exploring innovative solutions to tackle climate change and strengthen our water and energy resilience,” said CNRA Secretary Wade Crowfoot. “We are excited to see top research institutions come together to help deploy solar panels over water canals — a big idea with great potential. Science-driven collaborations like this one are critical to guide our path forward.”

CSCI researchers will evaluate solar canals’ potential to:

• Address the needs of a rapidly changing energy market;
• Through co-benefits, be competitive with other distributed-solar projects;
• Enhance current canal operations and maintenance procedures;
• Navigate existing water and land regulations; and
• Provide numerous benefits to communities where projects are developed.

USC Dornsife Public Exchange has assembled a multidisciplinary research team from faculty at seven universities: USC; UC Merced; University of California, Berkeley; University of California, Irvine; University of California College of the Law, San Francisco; San José State University; and University of Kansas.

The CSCI research is being guided by an advisory council of experts from government, academia and the private sector to ensure that its outcomes are actionable. The advisory council, chaired by Solar AquaGrid, includes members from DWR, CNRA, CEC, California Forward, New Energy Nexus, Environmental Policy Center and Stanford Water in the West.

The Potential of Solar Canals

While not all canals are suitable for solar installations, the UC Merced study estimated that covering all 4,000 miles of California’s exposed canals with solar panels could:

• Generate enough electricity to power about 2 million homes each year;
• Conserve enough water to meet the residential needs of up to 2 million people annually; and
• Reduce land use by up to 50,000 acres by placing solar arrays on existing infrastructure.

The study also indicated that covering significant portions of canals could provide benefits beyond power and water, including:

• Lowering maintenance costs by shading the canals, which reduces weed growth in the canals;
• Enhancing the efficiency of the solar panels due to the cooling effect of the water below; and
• Creating local jobs to install and maintain the systems.

Although California experienced multiple episodes of intense rainfall and flooding emergencies in the past two years, scientists predict the state will continue to swing between intense rainfall and prolonged droughts. Droughts have plagued the state for thousands of years, but they are worsened by climate change, emphasizing the continued need to conserve water and reduce greenhouse gas emissions while meeting the state’s increasing energy needs.

More information about CSCI — photos, a fact sheet, the names of faculty from each university and their areas of research — can be found at: https://publicexchange.usc.edu/csci-media-kit/.

Next Step in State’s Commitment to Renewable Energy and Land Conservation

CSCI represents a next step in the state’s commitment to exploring solar canal deployment to meet its 2045 clean energy goals and 30x30 conservation commitment. Those goals led to the creation of Project Nexus in 2023, the state’s first solar canal pilot project currently under construction in the Central Valley. The pilot is funded by the state of California and is a public-private-academic partnership between Turlock Irrigation District, Solar AquaGrid, UC Merced and the California Department of Water Resources.

 

About the Partners

USC Dornsife Public Exchange

Based at the University of Southern California, USC Dornsife Public Exchange connects a wide range of academic researchers with policy, industry and nonprofit partners that need their expertise to tackle complex challenges. The Public Exchange team is the project manager for CSCI. Its responsibilities include assembling and managing the faculty research team from the seven universities. The USC faculty associated with the project are from the USC Price School of Public Policy and the USC Viterbi School of Engineering[JB4] .

Solar AquaGrid

Solar AquaGrid is an independent advisory, envisioneering and advocacy firm committed to conserving water in an age of historic drought by addressing our water/energy nexus and covering our exposed canals with solar coverings to reduce evaporation, generate clean energy, save land and achieve numerous economic, environmental, and social advantages. The firm originated Project Nexus, the first solar canal pilot in California, after commissioning a UC Merced study in 2015 that revealed multiple potential benefits and is facilitating collaboration among public, private and academic partners to test different technologies and bring the solution to scale.

California Department of Water Resources (DWR) sustainably manages the water resources of California, in cooperation with other agencies, to benefit the state’s people and protect, restore and enhance the natural and human environments. This includes the State Water Project (SWP), the nation’s largest state-built water conveyance system. Sustainability is a priority as California strives to meet the water needs of today and those of the future while protecting and enhancing the environment. DWR is thus committed to exploring all efforts meant to advance the integration of renewable energy to provide clean energy to California.

California Natural Resources Agency (CNRA) works to restore, protect and manage California’s natural, historical and cultural resources for current and future generations using creative approaches and solutions based on science, collaboration and respect for all communities and interests involved. CNRA oversees and supports more than 26 distinct departments, conservancies and commissions, and over 21,000 Californians work within CNRA across the state.

California Energy Commission (CEC) is the state’s primary energy policy and planning agency. It has seven core responsibilities: advancing state energy policy, encouraging energy efficiency, certifying thermal power plants, investing in energy innovation, developing renewable energy, transforming transportation and preparing for energy emergencies.

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