Computer scientists unveil novel attacks on cybersecurity

Intel and AMD will issue security alerts today based on the findings

Reports and Proceedings

UNIVERSITY OF CALIFORNIA - SAN DIEGO

 

IMAGE: 

THE NEW PAPER, "PATHFINDER: HIGH-RESOLUTION CONTROL-FLOW ATTACKS EXPLOITING THE CONDITIONAL BRANCH PREDICTOR,"  DETAILS TWO NOVEL ATTACKS THAT COULD COMPROMISE THE BILLIONS OF INTEL PROCESSORS IN USE. 

view more 

CREDIT: HOSEIN YAVARZADEH

Researchers have found two novel types of attacks that target the conditional branch predictor found in high-end Intel processors, which could be exploited to compromise billions of processors currently in use. 

The multi-university and industry research team led by computer scientists at University of California San Diego will present their work at the 2024 ACM ASPLOS Conference that begins tomorrow. The paper, "Pathfinder: High-Resolution Control-Flow Attacks Exploiting the Conditional Branch Predictor," is based on findings from scientists from UC San Diego, Purdue University, Georgia Tech, the University of North Carolina Chapel Hill and Google.

They discover a unique attack that is the first to target a feature in the branch predictor called the Path History Register, which tracks both branch order and branch addresses. As a result, more information with more precision is exposed than with prior attacks that lacked insight into the exact structure of the branch predictor.

Their research has resulted in Intel and Advanced Micro Devices (AMD) addressing the concerns raised by the researchers and advising users about the security issues. Today, Intel is set to issue a Security Announcement, while AMD will release a Security Bulletin.

In software, frequent branching occurs as programs navigate different paths based on varying data values. The direction of these branches, whether "taken" or "not taken," provides crucial insights into the executed program data. Given the significant impact of branches on modern processor performance, a crucial optimization known as the "branch predictor" is employed. This predictor anticipates future branch outcomes by referencing past histories stored within prediction tables. Previous attacks have exploited this mechanism by analyzing entries in these tables to discern recent branch tendencies at specific addresses.

In this new study, researchers leverage modern predictors' utilization of a Path History Register (PHR) to index prediction tables. The PHR records the addresses and precise order of the last 194 taken branches in recent Intel architectures. With innovative techniques for capturing the PHR, the researchers demonstrate the ability to not only capture the most recent outcomes but also every branch outcome in sequential order. Remarkably, they uncover the global ordering of all branches. Despite the PHR typically retaining the most recent 194 branches, the researchers present an advanced technique to recover a significantly longer history.

“We successfully captured sequences of tens of thousands of branches in precise order, utilizing this method to leak secret images during processing by the widely used image library, libjpeg,” said Hosein Yavarzadeh, a UC San Diego Computer Science and Engineering Department PhD student and lead author of the paper.

The researchers also introduce an exceptionally precise Spectre-style poisoning attack, enabling attackers to induce intricate patterns of branch mispredictions within victim code. “This manipulation leads the victim to execute unintended code paths, inadvertently exposing its confidential data,” said UC San Diego computer science Professor Dean Tullsen.

"While prior attacks could misdirect a single branch or the first instance of a branch executed multiple times, we now have such precise control that we could misdirect the 732nd instance of a branch taken thousands of times,” said Tullsen.

The team presents a proof-of-concept where they force an encryption algorithm to transiently exit earlier, resulting in the exposure of reduced-round ciphertext. Through this demonstration, they illustrate the ability to extract the secret AES encryption key.

"Pathfinder can reveal the outcome of almost any branch in almost any victim program, making it the most precise and powerful microarchitectural control-flow extraction attack that we have seen so far," said Kazem Taram, an assistant professor of computer science at Purdue University and a UC San Diego computer science PhD graduate. 

In addition to Dean Tullsen and Hosein Yavarzadeh, other UC San Diego coauthors are. Archit Agarwal and Deian Stefan. Other coauthors include Christina Garman and Kazem Taram, Purdue University; Daniel Moghimi, Google; Daniel Genkin, Georgia Tech; Max Christman and Andrew Kwong, University of North Carolina Chapel Hill. 

This work was partially supported by the Air Force Office of Scientific Research (FA9550- 20-1-0425); the Defense Advanced Research Projects Agency (W912CG-23-C-0022 and HR00112390029); the National Science Foundation (CNS-2155235, CNS-1954712, and CAREER CNS-2048262); the Alfred P. Sloan Research Fellowship; and gifts from Intel, Qualcomm, and Cisco.

Responsible disclosure 

Researchers communicated the security findings outlined in the paper to both Intel and AMD in November 2023. Intel has informed other affected hardware/software vendors about the issues. Both Intel and AMD plan to address the concerns raised in the paper today through a Security Announcement and a Security Bulletin (AMD-SB-7015), respectively. The findings have been shared with the Vulnerability Information and Coordination Environment (VINCE), Case VU#157097: Class of Attack Primitives Enable Data Exposure on High End Intel CPUs.

 

---

ARTICLE TITLE

Pathfinder: High-Resolution Control-Flow Attacks Exploiting the Conditional Branch Predictor

ARTICLE PUBLICATION DATE

27-Apr-2024

 

Ancient Maya blessed their ballcourts

Researchers find evidence of ceremonial offerings beneath ballcourt in Mexico

UNIVERSITY OF CINCINNATI

 

IMAGE: 

UNIVERSITY OF CINCINNATI PROFESSOR DAVID LENTZ HOLDS UP A REPRODUCTION TILE FEATURING ANCIENT MAYA GLYPHS. RESEARCHERS DISCOVERED EVIDENCE OF CEREMONIAL OFFERINGS AT THE SITE OF AN ANCIENT MAYA BALLCOURT IN YAXNOHCAH, MEXICO.

view more 

CREDIT: ANDREW HIGLEY

For sports fans, places like Fenway Park, Wembley Stadium or Wimbledon's Centre Court are practically hallowed ground.

Archaeologists at the University of Cincinnati found evidence of similar reverence at ballcourts built by the ancient Maya in Mexico.

Using environmental DNA analysis, researchers were able to identify a collection of plants used in ceremonial rituals in the ancient Maya city of Yaxnohcah. The plants, known for their religious associations and medicinal properties, were discovered beneath a plaza floor upon which a ballcourt was built.

Researchers said the ancient Maya likely made a ceremonial offering during the ballcourt’s construction.

“When they erected a new building, they asked the goodwill of the gods to protect the people inhabiting it,” UC Professor David Lentz said. “Some people call it an ensouling ritual, to get a blessing from and appease the gods.”

The study was published in the journal PLOS ONE.

The research was carried out through Mexico's National Institute of Anthropology and History in collaboration with researchers from the University of Calgary, the Autonomous University of Campeche and the National Autonomous University of Mexico.

Researchers from 2016 to 2022 worked at Yaxnohcah in Campeche about 9 miles north of the border of Guatemala, where they excavated a small area of a ballcourt.

The ancient Maya played several ball games, including pok-a-tok, which has rules similar to soccer and basketball. Players tried to get a ball through a ring or hoop on a wall.

UC Professor Emeritus Nicholas Dunning said when buildings were expanded or repurposed, as with the ballcourt, the ancient Maya made offerings to bless the site. Archaeologists sometimes find ceramics or jewelry in these offerings along with plants of cultural significance.

“We have known for years from ethnohistorical sources that the Maya also used perishable materials in these offerings, but it is almost impossible to find them archaeologically, which is what makes this discovery using eDNA so extraordinary,” Dunning said.

Ancient plant remains are rarely discovered in tropical climates, where they decompose quickly. But using environmental DNA, researchers were able to identify several types known for their ritual significance.

They discovered evidence of a morning glory called xtabentun, known for its hallucinogenic properties, lancewood, chili peppers and jool, the leaves of which were used to wrap ceremonial offerings.

Botanist and UC Associate Professor Eric Tepe said finding evidence of these plants together in the same tiny sediment sample is telling. He has studied modern plants in the same forests once traveled by the ancient Maya.

“I think the fact that these four plants which have a known cultural importance to the Maya were found in a concentrated sample tells us it was an intentional and purposeful collection under this platform,” Tepe said.

Researchers noted the challenge of trying to interpret a collection of plants through the opaque lens of 2,000 years of prehistory. But Lentz said the findings help add to the story of this sophisticated culture.

Researchers believe the ancient Maya devised water filtration systems and employed conservation-minded forestry practices. But they were helpless against years-long droughts and also are believed to have deforested vast tracts for agriculture.

“We see the yin and yang of human existence in the ancient Maya,” Lentz said. “To me that’s why they’re so fascinating.”

UNIVERSITY OF CINCINNATI PROFESSOR DAVID LENTZ, PICTURED HERE AT TIKAL, DISCOVERED EVIDENCE OF CEREMONIAL OFFERINGS AT THE SITE OF AN ANCIENT MAYA BALLCOURT IN YAXNOHCAH, MEXICO.

CREDIT

Liwy Grazioso Sierra

JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0301497 

METHOD OF RESEARCH

Imaging analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Psychoactive and other ceremonial plants from a 2,000-year-old Maya ritual deposit at Yaxnohcah, Mexico

ARTICLE PUBLICATION DATE

26-Apr-2024

 

CRISPR is promising to tackle antimicrobial resistance, but remember bacteria can fight back

Experts looking to use the Nobel winning technology to target resistance genes and make bacteria sensitive to first line antibiotics again; but the bacteria have ways to fight back

EUROPEAN SOCIETY OF CLINICAL MICROBIOLOGY AND INFECTIOUS DISEASES

In the second new research review on this subject, Assistant Prof. Ibrahim Bitar, Department of Microbiology, Faculty of Medicine and University Hospital in Plzen, Charles University in Prague, Plzen, Czech Republic, will give an overview of the molecular biology of CRISPR technology in explaining how it can used to tackle antimicrobial resistance.

Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR associated genes (cas) are widespread in the genome of many bacteria and are a defence mechanism against foreign invaders such as plasmids and viruses.  The CRISPR arrays are composed of a repeated array of short sequences, each originating from and exactly matching a nucleic acid sequence that once invaded the host.

Accompanying CRISPR sequences, there are 4-10 CRISPR-associated genes (cas), which are highly conserved and encode the Cas proteins. Cas proteins conduct adaptive immunity in prokaryotes (bacteria) based on immunological memories stored in the CRISPR array. The CRISPR/Cas system integrates a small piece of foreign DNA from invaders such as plasmids and viruses into their direct repeat sequences and will recognise and degrade the same external DNA elements during future invasions.

As the CRISPR/Cas systems integrate DNA from invading pathogens in chronical order, genotyping can be used to trace the clonality and the origin of the isolates and define them as a population of strains that were subjected to the same environmental conditions including geographic location (region) and community/hospital settings and eventually further extended to track pathogenic bacteria around human society.

CRISPR/Cas systems can also be employed for developing antimicrobial agents: introduction of self-targeting crRNAs will effectively and selectively kill target bacterial populations. Due to the shortage of available effective antimicrobial agents in treating multidrug-resistant (MDR) infections, researchers started to search for alternative methods to fight MDR infections rather than going through the process of developing new antimicrobial agents which can go on for decades. As a result, the concept of CRISPR/Cas-based selective antimicrobials was first developed and demonstrated in 2014. Vectors coding Cas9 and guide RNAs targeting genomic loci of a specific bacterial strain/species can be delivered to the target strain via bacteriophages or conjugative bacterial strains. In theory, delivery of the engineered CRISPR/Cas systems specifically eliminates target strains from the bacterial population, yet it is not that simple.

While these systems can seem a target for manipulation/intervention, all bacteria are regulated by multiple pathways to ensure the bacteria retains control over the process. Therefore, there remain several major challenges in using this system as an antimicrobial agent.

Most methods require delivery of the re-sensitised system by conjugation; the vector is carried by a non-virulent lab strain bacteria that is supposed to go and share the vector/plasmid through conjugation. The conjugation process is a natural process that the bacteria do which results in sharing plasmids among each other (even with other species). The percentage of conjugated (successfully delivered) bacteria in the total bacterial population is critical to the re-sensitised efficiency. This process is governed by several complicated pathways.

Bacteria also possess built-in anti-CRISPR systems, that can repair any damage caused by CRISPR-Cas systems. Defence systems that the bacteria uses to protect itself from foreign DNA often co-localise within defence islands (genomic segments that contain genes with similar function in protecting the host from invaders)  in bacterial genomes; for example: acr (a gene that acts, with other similar variants, as a repressor of plasmid conjugative systems) often cluster with antagonists of other host defence functions (e.g., anti-restriction modification systems) and experts hypothesise that MGEs (mobile genetic elements) organise their counter defence strategies in “anti-defence” islands.

Assistant Professor Bitar concludes: “In summary, this method seems very promising as an alternative way of fighting antimicrobial resistance. The method uses the concept of re-sensitising the bacteria in order to make use of already available antibiotics – in other words, removing their resistance and making them vulnerable again to first-line antibiotics. Nevertheless, the bacterial pathways are always complicated and such systems are always heavily regulated by multiple pathways. These regulated pathways must be studied in depth in order to avoid selective pressure favoring anti-CRISPR systems activation, hence prevalence of resistance in a more aggressive manner.”

 

Experts developing way to harness Nobel Prize winning CRISPR technology to deal with antimicrobial resistance (AMR)

EUROPEAN SOCIETY OF CLINICAL MICROBIOLOGY AND INFECTIOUS DISEASES

Antimicrobial resistance (AMR) is continuing to increase globally, with rates of AMR in most pathogens increasing and threatening a future in which every day medical procedures may no longer be possible and infections thought long dealt with could kill regularly again. As such, new tools to battle AMR are vitally needed.

In a new research review at this year’s ESCMID Global Congress (formerly ECCMID – Barcelona 27-30 April) shows how the latest CRISPR-Cas gene editing technology can be used to help modify and attack AMR bacteria. The presentation is by Dr Rodrigo Ibarra-Chávez, Department of Biology, University of Copenhagen, Denmark.

CRISPR-Cas gene editing technology is a groundbreaking method in molecular biology that allows for precise alterations to the genomes of living organisms. This revolutionary technique, which brought its inventors, Jennifer Doudna and Emmanuelle Charpentier, the Nobel Prize in Chemistry in 2020, enables scientists to accurately target and modify specific segments of an organism's DNA (genetic code). Functioning like molecular ‘scissors’ with the guidance of guide RNA (gRNA), CRISPR-Cas can cut the DNA at designated spots. This action facilitates either the deletion of unwanted genes or the introduction of new genetic material into an organism's cells, paving the way for advanced therapies.

Dr Ibarra-Chávez says: “Fighting fire with fire, we are using CRISPR-Cas systems (a bacterial immunity system) as an innovative strategy to induce bacterial cell-death or interfere with antibiotic resistance expression – both hold promise as novel sequence-specific targeted ‘antimicrobials’.”

One line of their work involves creating guided systems against antimicrobial resistance genes could treat infections and prevent dissemination of resistance genes.

Mobile genetic elements (MGEs) are parts of the bacterial genome that can move about to other host cells or also transfer to another species. These elements drive bacterial evolution via horizontal gene transfer.  Dr Ibarra-Chávez explains how repurposing mobile genetic elements (MGEs) and choosing the delivery mechanism involved in the antimicrobial strategy is important for reaching the target bacterium.

A phage is a virus that infects bacteria, and it is also considered MGE, as some can remain dormant in the host cell and transfer vertically. The MGEs his team is using are phage satellites, which are parasites of phages. He says: “These ‘phage satellites’ hijack parts of the viral particles of phages to ensure their transfer to host cells. In contrast to phages, satellites can infect bacteria without destroying them, offering a step-change over existing methods involving phages and thus developing an arsenal of viral particles that are safe to use for applications such as detection and modification via gene delivery. Phage particles are very stable and easy to transport and apply in medical settings. It is our task to develop safe guidelines for their application and understand the resistance mechanisms that bacteria can develop.”

Bacteria can evolve mechanisms to evade the action of the CRISPR-Cas system and delivery vectors can be vulnerable to anti-MGE defences. Thus Dr Ibarra-Chávez’s team and others are developing the use of anti-CRISPRs and defence inhibitors in the delivery payloads to counter these defences, to enable the CRISPR to arrive and attack the AMR genes in the cell.

Dr Ibarra-Chávez will also discuss how combination strategies employing CRISPR-Cas systems could promote antibiotic susceptibility in a target bacterial population. Phages have a particular selective pressure on AMR cells, which can improve the effect of some antibiotics. Similarly, using CRISPR-Cas in combination with phages and/or antibiotics, it is possible to suppress the mechanisms of resistance that infectious bacteria may develop by targeting such virulence/resistance genes, making these therapies safer.

He explains: “Bacteria are particularly good at adapting and becoming resistance. I believe we need to be cautious and try using combinatorial strategies to avoid the development of resistance, while monitoring and creating guidelines of new technologies.”

Dr Ibarra-Chávez has primarily focused on tackling resistance in Staphylococcus aureus and Escherichia coli. Now, in collaboration with Prof. Martha Clokie and Prof. Thomas Sicheritz-Pontén, his team will treat group A Streptococci necrotising soft tissue infection (flesh eating bacteria) using the combination approaches described above.

 

---

ARTICLE PUBLICATION DATE

26-Apr-2024

---

 

Food insecurity is significant among inhabitants of the region affected by the Belo Monte dam in Brazil

A study of 500 households in Altamira, a city near the dam in Pará state, showed that 61% experienced food insecurity

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

 

IMAGE: 

A PARTIAL VIEW OF THE CITY OF ALTAMIRA, PARÁ, IN AUGUST 2022, WITH THE XINGU RIVER IN THE BACKGROUND 

view more 

CREDIT: IGOR CAVALLINI JOHANSEN

The social and environmental impact of the Belo Monte dam and hydroelectric power plant in Pará state, Brazil, has been called a “disaster” by researchers, environmentalists and several media outlets. The damage has again been highlighted recently in an inspection report issued by the Brazilian Institute for the Environment and Renewable Natural Resources (IBAMA), an agency of the Ministry for the Environment and Climate Change. The inspectors detected silting and erosion of the Xingu River, obstacles to river navigation, a significant increase in tree mortality, and the impossibility of reproduction for several fish species, as well as disruptions to the way of life of Indigenous and river-dwelling communities.

A new study conducted with FAPESP’s support focuses specifically on food insecurity in Altamira, which is the city with the largest population in the region and has been dramatically affected by the construction of Belo Monte. Because of the megaproject, Altamira became a hub for the distribution of goods, services and the logistics essential to the construction process, with a significant impact on its population. 

Construction took place between 2011 and 2015, causing the city’s population to grow without adequate planning to assure the provision of services to residents and migrants looking for work. The shock made Altamira one of Brazil’s most violent cities. Although its population has declined since the dam was completed, the 2022 census recorded 126,279 inhabitants, 27.46% more than in 2010, when the previous census was conducted. This growth rate compares with 6.46% for Brazil’s total population growth in the same period.

The study, published in the International Journal of Environmental Research and Public Health, shows that 61% of Altamira’s households experienced some level of food insecurity and malnutrition in 2022, when the data was collected. 

“We conducted the survey in July 2022, seven years after construction ended, visiting 500 households selected as representative of the city’s socioeconomic strata and geographic areas. The scale used to measure household food insecurity is divided into three categories. We found the worst food insecurity in the poorest group, where heads of household had low levels of educational attainment and unemployment was high. In addition, the households with severe food insecurity had more members. Families displaced by the dam and resettled elsewhere also experienced severe food insecurity,” said Igor Cavallini Johansen, first author of the article. Johansen is a demographer and a postdoctoral researcher affiliated with the State University of Campinas’s Center for Environmental Studies (NEPAM-UNICAMP) in São Paulo state.

Unlike other studies of food insecurity in the context of hydroelectric developments in Brazil, this one used the Brazilian Household Food Insecurity Scale, known by the Portuguese-language acronym EBIA, Johansen said, explaining that the scale is based on a scientifically validated methodology for measuring access to sufficient food of adequate quality. 

“The survey included a questionnaire with eight standardized items. The responses were scored using the EBIA scale to arrive at a classification of food insecurity for each household in the sample,” he said.

The households were classified into the following categories: (1) food security (adequate food quantity and quality); (2) mild food insecurity (food quality impaired and uncertainty regarding future food availability; (3) moderate food insecurity (inadequate diet, food becoming scarce within the household, children prioritized over adults); (4) severe food insecurity (insufficient food for all household members).

“We formulated three hypotheses: (1) households were affected by a range of factors that together produced food insecurity; (2) poverty played a key role, and the most affected groups were those who had been forced to leave their homes and had been resettled in purpose-built housing projects, known as RUCs; and (3) besides the impact of the dam, the problem was made worse by the COVID-19 pandemic,” Johansen said.

The survey also took into account several socioeconomic variables as correlates of food insecurity, such as a wealth index (poorest, intermediate, least poor) considering the characteristics of the home, ownership of vehicles and appliances, etc.; whether respondents were monthly handouts from the Bolsa Família conditional cash transfer program; whether they had officially declared themselves affected by the dam; whether they lived in an RUC; the number of household members and over-sixties; and the head of household’s gender, skin color, age, marital status, educational attainment and employment status. 

“All three hypotheses were confirmed. Predictably, the various factors correlated with each other: the impact of the dam’s construction significantly increased the probability that household members lived in an RUC, and this increased the likelihood that a family was poor, which in turn entailed a risk of food insecurity,” Johansen said. “Access to food of the desired quantity and quality became more difficult for 69.7% of the households after construction of the dam was completed in 2015.” About half of these households (52.5%) said it had already been difficult before the pandemic, and the rest blamed the pandemic for the worsening of food insecurity since then.

“We also found that households with one or more members aged 60 and over experienced less food insecurity. This can be attributed to the contribution of old-age pensions to the household income, potentially reducing their exposure to poverty and hence to food insecurity,” he noted.

The lack of a survey conducted before the dam’s construction and based on the EBIA scale was unfortunate, Johansen added, as this could have been compared with the results obtained after its construction. “In any event, it was a shock to find that 61% of the households experienced food insecurity when the consortium that built the dam claimed to have invested BRL 6.5 billion, or about USD 1.3 billion, in social, environmental and sustainability-related measures in the region between 2016 and 2022. What was all that money used for?” he said.

The negative impact of Belo Monte is not an isolated case. Several other megaprojects implemented in the Amazon have also had significant social and environmental side effects. Another study conducted by the same research group and led by Caroline Arantes, a professor at West Virginia University in the United States showed that fishing communities lost production and income after construction of the Santo Antônio and Jirau hydroelectric projects in Porto Velho, Rondônia state. The communities were forced to adapt their fishing strategies and find other ways to earn a living in response to the impact of the dams. Household consumption of fish diminished significantly as a result. “These communities had always had fish meals every day, but after the dams were built they were able to do so only once or twice a week, if not less often,” Johansen said. The study in question is published in the Journal of Environmental Management.

Another prior study, in this case focusing on a fishing community on the Xingu River after construction of Belo Monte, showed that fish became scarce and food in general became more expensive in the region. An article on this study is published in the journal Human Ecology.

All these studies involved contributions by Professor Emilio F. Moran, principal investigator for the project “After hydropower dams: social and environmental processes that occur after the construction of Belo Monte, Jirau and Santo Antônio in Brazilian Amazon”, and supported by FAPESP via the São Paulo Excellence Chair program (SPEC). 

In addition to this grant, the study was supported by a postdoctoral scholarship awarded to Johansen, and a postdoctoral scholarship awarded to Vanessa Cristine e Souza Reis, also a member of the research group.

About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

 

---

JOURNAL

International Journal of Environmental Research and Public Health

DOI

10.3390/ijerph21020155 

ARTICLE TITLE

Poverty–Food Insecurity Nexus in the Post-Construction Context of a Large Hydropower Dam in the Brazilian Amazon

 

Large Hadron Collider experiment zeroes in on magnetic monopoles

by Ana Lopes, CERN

The MoEDAL detector. Credit: CERN

The late physicist Joseph Polchinski once said the existence of magnetic monopoles is "one of the safest bets that one can make about physics not yet seen." In its quest for these particles, which have a magnetic charge and are predicted by several theories that extend the Standard Model, the MoEDAL collaboration at the Large Hadron Collider (LHC) has not yet proven Polchinski right, but its latest findings mark a significant stride forward.

The results, reported in two papers posted on the arXiv preprint server, considerably narrow the search window for these hypothetical particles.

At the LHC, pairs of magnetic monopoles could be produced in interactions between protons or heavy ions. In collisions between protons, they could be formed from a single virtual photon (the Drell–Yan mechanism) or the fusion of two virtual photons (the photon-fusion mechanism). Pairs of magnetic monopoles could also be produced from the vacuum in the enormous magnetic fields created in near-miss heavy-ion collisions, through a process called the Schwinger mechanism.

Since it started taking data in 2012, MoEDAL has achieved several firsts, including conducting the first searches at the LHC for magnetic monopoles produced via the photon-fusion mechanism and through the Schwinger mechanism.

In the first of its latest studies, the MoEDAL collaboration sought monopoles and high-electric-charge objects (HECOs) produced via the Drell–Yan and photon-fusion mechanisms. The search was based on proton–proton collision data collected during Run 2 of the LHC, using the full MoEDAL detector for the first time.

The full detector comprises two main systems sensitive to magnetic monopoles, HECOs and other highly ionizing hypothetical particles. The first can permanently register the tracks of magnetic monopoles and HECOs, with no background signals from Standard Model particles. These tracks are measured using optical scanning microscopes at INFN Bologna.

The second system consists of roughly a ton of trapping volumes designed to capture magnetic monopoles. These trapping volumes—which make MoEDAL the only collider experiment in the world that can definitively and directly identify the magnetic charge of magnetic monopoles—are scanned at ETH Zurich using a special type of magnetometer called a SQUID to look for any trapped monopoles they may contain.

In their latest scanning of the trapping volumes, the MoEDAL team found no magnetic monopoles or HECOs, but it set bounds on the mass and production rate of these particles for different values of particle spin, an intrinsic form of angular momentum.

For magnetic monopoles, the mass bounds were set for magnetic charges from 1 to 10 times the fundamental unit of magnetic charge, the Dirac charge (gD), and the existence of monopoles with masses as high as about 3.9 trillion electronvolts (TeV) was excluded.

For HECOs, the mass limits were established for electric charges from 5e to 350e, where e is the electron charge, and the existence of HECOs with masses ranging up to 3.4 TeV was ruled out.

"MoEDAL's search reach for both monopoles and HECOs allows the collaboration to survey a huge swathe of the theoretical 'discovery space' for these hypothetical particles," says MoEDAL spokesperson James Pinfold.

In its second latest study, the MoEDAL team concentrated on the search for monopoles produced via the Schwinger mechanism in heavy-ion collision data taken during Run 1 of the LHC. In a unique endeavor, it scanned a decommissioned section of the CMS experiment beam pipe, instead of the MoEDAL detector's trapping volumes, in search of trapped monopoles.

Once again, the team found no monopoles, but it set the strongest-to-date mass limits on Schwinger monopoles with a charge between 2gD and 45gD, ruling out the existence of monopoles with masses of up to 80 GeV.

"The vital importance of the Schwinger mechanism is that the production of composite monopoles is not suppressed compared to that of elementary ones, as is the case with the Drell–Yan and photon-fusion processes," explains Pinfold. "Thus, if monopoles are composite particles, this and our previous Schwinger-monopole search may have been the first-ever chances to observe them."

The MoEDAL detector will soon be joined by the MoEDAL Apparatus for Penetrating Particles, MAPP for short, which will allow the experiment to cast an even broader net in the search for new particles.

More information: Search for Highly-Ionizing Particles in pp Collisions During LHC Run-2 Using the Full MoEDAL Detector, arXiv (2023). DOI: 10.48550/arxiv.2311.06509

B. Acharya et al, MoEDAL search in the CMS beam pipe for magnetic monopoles produced via the Schwinger effect, arXiv (2024). DOI: 10.48550/arxiv.2402.15682

Journal information: arXiv 

Provided by CERN ATLAS experiment places some of the tightest limits yet on magnetic monopoles

 

Ridesourcing platforms thrive on socio-economic inequality, say researchers

by Delft University of Technology

Credit: Pixabay/CC0 Public Domain

Platforms that offer rides to passengers, such as Uber and DiDi, thrive on socio-economic inequality. By modeling the behavior of passengers and self-employed drivers, researchers of TU Delft simulated the market for ridesourcing platforms, evaluating a broad spectrum of (in)equality levels in societies.

It explains why in some cities ridesourcing services can be big players in the mobility system, while in other cities they don't get off the ground. The research was published in Scientific Reports recently.

What if everybody had the same income? Or what if almost all money was held by one person? With these extremes of (in)equality, TU Delft researchers simulated the market for ridesourcing platforms, such as Uber or DiDi. They uncovered a compelling relationship between socio-economic inequality and the market share of the platforms. Oded Cats, professor of Passenger Transport Systems said, "These extremes help contextualize real-world dynamics, where all societies worldwide fall somewhere in between."

To move towards a sustainable urban mobility system, new designs prioritize the enhancement of public transport. Understanding how to reinforce public transit and improve access to public transport hubs for passengers is crucial.

"In cities like Amsterdam, with relatively low inequality, short travel distances and well-established bicycle and public transport networks, Uber is unlikely to flourish," researcher Arjan de Ruijter explains. "Therefore, transport authorities in such cities should rather focus on providing shared bikes and scooters to improve station access."

Conversely, in cities marked by significant inequality, like Johannesburg or Rio de Janeiro, Uber-like ridesourcing platforms thrive. Various explanations, taking into account driver's and passenger's behavior, emerge in the study. The platform capitalizes on a workforce willing to accept lower wages, leading to a service with limited waiting times for passengers. Moreover, it acknowledges the demand for mobility on demand among the affluent segments of unequal societies, willing to pay for a premium-like service.

These insights can explain and predict the potential dominance of Uber-like services in the design of a mobility system. Adding to that, it provides guidance for designing inclusive mobility systems and assessing the necessity for regulatory measures.

De Ruijter observed how these platforms adapt their strategies based on inequality. "In a society with high inequality, companies can charge higher commissions to drivers, as drivers have limited alternative labor opportunities."

Cats adds, "On the other hand, in societies with low inequality, all else being equal, pricing strategies must attract more selective job seekers, resulting in lower commission rates." This illustrates the interplay between socio-economic factors and the viability of ridesourcing platforms.

Because of the lack of data on ridesourcing market shares in different cities, the researchers decided to model the behavior of the key players in the market and experiment with different market settings.

Their model may also be useful in investigating inequality effects in meal and grocery delivery markets, provided by platforms such as Just Eat Takeaway and Getir. These service-platforms also seem to flourish on a group of relatively affluent users willing to pay for service, and a group of drivers willing to do low-wage work.

More information: Arjan de Ruijter et al, Ridesourcing platforms thrive on socio-economic inequality, Scientific Reports (2024). DOI: 10.1038/s41598-024-57540-x

Journal information: Scientific Reports 

Provided by Delft University of Technology How does ridesourcing substitute for public transit network?

 

Did Vesuvius bury the home of the first Roman emperor?

by University of Tokyo

A haunting sight at the archaeological site. The face of a statue of the god Dionysus as it's 

painstakingly chipped away from and brushed free of millennia of built-up deposits. 

Credit: 2024 Institute for Advanced Global Studies CC-BY-ND

A group of archaeologists, led by researchers from the University of Tokyo, announce the discovery of a part of a Roman villa built before the middle of the first century. This villa, near the town of Nola in southwestern Italy's Campania region, was found beneath a more recent, but still ancient building from the 2nd century.

Specific findings at the site, buried by multiple eruptions of Mount Vesuvius, suggest it might have been the home of Gaius Julius Caesar Augustus (Octavian), the founding emperor of the Roman Empire, as they coincide with contemporary writings by known Roman writers Tacitus, Suetonius, and Dio Cassius.

This excavation is also significant as it was previously thought that only areas to the south of Vesuvius, famously the ancient Roman cities of Pompeii and Herculaneum, were heavily damaged, but this villa is located in the valley of Somma Vesuviana to the north.

In 1929, a farmer discovered, by accident, part of an abandoned building buried in a field. Archaeologists set to work excavating the site to reveal an extravagant villa that strongly hinted at being the residence of Augustus. However, the financial condition at that time impeded further exploration of the site.

This situation changed in 2002 when the University of Tokyo began an interdisciplinary project, in collaboration with local archaeologists, to fully excavate the villa and learn about this potentially significant area. Since then, many Roman objects, beautiful marble statues—including two pieces fit enough to be displayed in a museum—a huge building with various rooms, wall paintings, stucco reliefs and mosaics have been revealed.

An archaeologist stands next to a pillar, showing the magnitude of the ancient dwelling. 

Credit: 2024 Institute for Advanced Global Studies CC-BY-ND

"Excavations around Mount Vesuvius have been ongoing since the 18th century. It was known that beneath the ash and debris from the biggest eruption in A.D. 79, various Roman artifacts lay buried," said Kohei Sugiyama, an archaeologist from the Institute for Advanced Global Studies at the University of Tokyo.

"Most exploration related to that are focused on regions to the south of the volcano as that is where the majority of ejecta fell, and damage was suffered. For over 20 years, we have excavated large sections of the villa and have recently uncovered some previously unknown rooms and other architectural elements.

"Using radiocarbon dating, and with help from volcanologists to perform extra analysis, we determined that these newly discovered sections are buried under volcanic material from the A.D. 79 eruption."

Ejected volcanic rocks from the A.D. 79 eruption of Mount Vesuvius. 

Credit: 2024 Institute for Advanced Global Studies CC-BY-ND

Pots buried under ash and other pyroclastic materials of the A.D. 79 eruption of Mount Vesuvius give clues about the levels of volcanic damage to the villa. 

Credit: 2024 Institute for Advanced Global Studies CC-BY-ND

Sugiyama and his team revealed significant destruction in the northern area of Mount Vesuvius, including damage from lava flows and pyroclastic surges, the big explosions you see people running from in movies about volcanoes.

At the site of the villa during the 2002 excavations, volcanologists in the team revealed the upper levels of the building were constructed by the mid-second century, and that the villa was built upon some of the partially obscured structures that came before it.

This finding indicates the resilience and rebuilding efforts of the people following the disaster of A.D. 79 in the area of Somma Vesuviana, unlike Pompeii, where the thick layers of volcanic ash and pyroclastic flows left the city abandoned for many centuries.

"This kind of investigation is important for several reasons," said Sugiyama. "Not only does it connect physical evidence with Augustus, who is mainly known through historic writings, but it also tells us about the local economy and society in that region at that time, which may have been more prosperous and significant than was previously thought.

"Learning about how ancient people recovered from disasters could inform how we plan for such things today. It's challenging to carry out this kind of archaeology due to the heavy machinery needed to dig down to 15 meters and move large boulders, and of course funding can often be an issue."

Provided by University of Tokyo Harnessed horse unearthed in ancient stable near Pompeii