2023 Impact factor 1.8
Soft Matter and Biological Physics

EPJ B Highlight - How did the COVID pandemic end so abruptly?

US Covid Max. Daily Deaths. Credit: Moret and Phillips

New analysis suggests that a dramatic drop in deaths from COVID-19 between 2022 and 2023 could be attributed to an abrupt phase transition in the molecular structure of the virus’ spike protein.

During the winter of 2020 and 2021, the US saw deaths from COVID-19 reach 250,000. The following year, this number surged by a third to 330,000. But from August 2022 to March 2023, the number of deaths related to COVID-19 deaths plummeted to just 80,000, abruptly ending the COVID pandemic. This dramatic decline couldn’t be attributed solely to vaccines, which had been already widely available since Spring 2021.

Through new research published in EPJ B Marcelo Moret of CIMATEC in Brazil, together with James Phillips at Rutgers University, New Jersey, suggest that a phase transition in the molecular structure of the COVID-19 spike protein made the virus less likely to cause severe infections. Their results offer important insights into how the pandemic ended so quickly, and could help us to prepare for future pandemics.

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EPJ B Highlight - Scheduling meetings: Are the odds in your favour?

Histogram of probabilities πi that a poll will yield exactly i viable meeting times. Credit: K. Brown et al.

The results of an exploration of the mathematical theory behind Doodle polls that began in jest may be applicable to many other situations that require consensus-building.

If you often schedule meetings, you are likely to know how difficult it is to pick a time that suits everyone. Furthermore, the advent of tools like Doodle can make it harder: all too often, a poll will ‘fail’ with no mutually acceptable slot found. It would surely be useful to know the probability that a poll with a given number of participants and slots will generate a suitable time.

Three US-based theoretical physicists have now generated mathematical models of this problem and published them in EPJ B. “Our study began almost as a joke, when we were irritated by the growing number of polls we had to complete”, says first author Harsh Mathur from Case Western University, Cleveland, OH. “But we found that the models we produced were mathematically sophisticated and could be useful more widely.”

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EPJ B Highlight - Assessing the environmental impacts of Brazil’s biofuel sector

Assessing the dependence of biofuels on other sectors

Mathematical analysis reveals that within Brazil’s agriculture and livestock industry, the biofuels sector is most heavily reliant on other sectors with high greenhouse gas emissions.

Brazil is a world leader in biofuel production, but the environmental sustainability of the sector has faced criticism due to its impacts on deforestation, water use, and biodiversity, especially in the Amazon rainforest.

Through analysis published in EPJ B, researchers led by Eder Johnson de Area Leão Pereira at the Federal Institute of Maranhão reveal new insights into the biofuel industry's dependence on high greenhouse gas (GHG) emitting sectors.

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EPJ B Highlight - Thinking about the rise of brain-inspired computing

A diagram showing the overlap of different computing regimes Credit: M. Zolfagharinejad, et al., EPJ B (2024)

A new review paper looks at the growing and interdisciplinary area of research that investigates how principles of the biological brain can be translated to computers.

The recent widespread and long-lasting chaos caused by Microsoft outages across the globe exemplifies just how integral computing has become to our lives. Yet, as computer hardware and software improve, arguably the most sophisticated and powerful computer we know of is still the human brain.

Sharing its computing power through billions of neurons interacting via trillions of synapses, the human brain doesn’t just compete with the most powerful supercomputers devised, but by consuming less energy than it takes to power the light in your fridge, your brain beats computers in the efficiency department, hands down.

It is little wonder that scientists and computer engineers are inspired by the human brain when it comes to devising new computing methods.

In a new paper published in the journal EPJ B, Mohamadreza Zolfagharinejad from the University of Twente and his coauthors discuss the rise of brain-inspired computing, its burgeoning demand, and its importance in the modern world. The review offers a comprehensive overview of the latest advances in brain-inspired computing hardware.

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EPJ B Highlight - Five ways to model text using networks

Some examples of how words connect to each other in a text, forming a network. While words such as “vertex” and “vertices” are connected for their shared form, words such as “texts”, “sentences” and “words” are connected because of their meanings. © D A Oliveira

Network theory can be used in different ways to model the relationship between words in a block of text, linking analytical patterns to coherence and to some more subjective aspects of writing quality.

The explosive growth of AI ‘chatbots’ over the last few years and their ability to generate text that simulates human writing, often very accurately, has focused attention on how text is structured.

One useful way of analysing text is to think of it as a network, and methods of network analysis that are familiar to mathematicians and computer scientists can be powerful in linguistics. Davi Alves Oliveira and Hernane Borges de Barros Pereira from the University of Bahia State, Bahia, Brazil have compared five methods of representing sentences as networks, showing that each has value for specific applications. This analysis has now been published in the journal EPJ B.

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EPJ B Topical review - Twenty-five years of random asset exchange modeling

Over the last twenty-five years, there has emerged within the subfield of econophysics a sizeable and important literature (hereinafter the “random asset exchange” literature) concerned with the application of stochastic processes to model wealth and income distributions. In a new Topical Review published in EPJ B, written by Max Greenberg (University of Massachusetts Amherst, USA) and H. Oliver Gao (Cornell University, USA), the random asset exchange literature as a whole is comprehensively exposited for the first time.

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EPJ B Highlight - A Mathematical Understanding of Project Schedules

A toy project with three interdependent activities A, B and C. The longest activity (A) sets the project duration. Copyright A. Vazquez

Complex projects are made up of many activities, the duration of which vary according to a power law; this model can be used to predict overall project duration and delay.

We have all been frustrated when a project is delayed because one sub-task cannot begin before another ends. It is less well known that the process of scheduling projects efficiently can be described in mathematical terms. Now, Alexei Vazquez, of technology company Nodes & Links and based in Cambridge, UK, has shown that the distribution of activity lengths in a project follows the mathematical relationship of power law scaling. He has published his findings in the journal EPJ B.

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EPJ B Highlight - Coalescence-fragmentation cycles based on Human conflict

Lewis Richardson’s models of insurgency warfare applies to general group dynamics. Credit: NOAA Presentation/Public Domain

Inspired by insurgency warfare dynamics, a model predicts patterns of how groups gel and shatter

In 1960, Lewis Fry Richardson famously observed that the severity of a wartime event is described by a simple power law distribution that scales according to the size of the conflict. Statisticians since have since proposed various modifications, but they continue to agree that casualty count in a violent conflict tends to scale with the size of the insurgent group that caused the conflict. In a study published in EPJ B, Brennen Fagan, of the University of York, UK, and his colleagues analyze models of how complex systems coalesce and fragment based on these warfare dynamics. Their work evaluates the robustness of these models and elucidates the relationship between microscopic dynamics and observed phenomena.

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EPJ B Highlight - Exploring exotic behaviours in population-imbalanced fermionic systems

Forming exotic phases of matter

New studies show that oscillations in the quantum states of composite particles in trapped systems can be adjusted using an external magnetic field.

Over the past 20 years, many physicists have studied ultra-cold fermionic systems contained in magnetic or optical traps. When an external magnetic field is applied to a two-species fermionic system, the particles can pair together to form composite ‘bosonic molecules’ with a full-integer spin. These molecules undergo “Bose-Einstein Condensation” when cooled, where all the particles accumulate in the lowest-energy quantum state. The precision of these experiments has now been improved by trapping the particles inside optical lattices: periodic patterns formed by counter-propagating laser beams.

Through new research published in EPJ B, Avinaba Mukherjee and Raka Dasgupta at the University of Calcutta, India, have theoretically predicted a distinctive trend in the oscillations of Bose-Einstein condensates formed from these fermions – which can be adjusted using an external magnetic field. They specifically addressed systems where the two species have unequal population (creating leftover unpaired fermions): leading to exotic new phases. Their result could help physicists to detect such novel phases of matter in imbalanced fermionic systems and could open up new opportunities for quantum technologies.

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EPJ B Highlight - Harvesting vibrational energy from coloured noise

Schematic diagram of a tri-stable energy harvesting system with linked electronics and energy store. Credit: T. Zhang, Y. Jin

Two engineers from Beijing Institute of Technology in China have shown how to optimise the output of a device that can convert ambient vibrational energy into useful electric power.

The energy demands of today’s ubiquitous small electronic devices – including sensors, data transmitters, medical implants and ‘wearable’ consumer products such as Fitbits – can no longer be met by chemical batteries alone. This gap can be filled by energy harvesters, which turn ordinary, ambient vibrational energy into electrical energy. The most efficient types of harvester are tri-stable energy harvesters, which can convert even low-frequency random vibrations into alternating current (AC) and thence into direct current (DC). Tingting Zhang and Yanfei Jin from Beijing Institute of Technology in China have now investigated how the properties of these systems can be altered to optimise the power output; their findings are published in EPJ B.

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Editors-in-Chief
F. Croccolo, G. Fragneto and H. Stark
I was very glad to accept your invitation to review the manuscript of such a high scientific level that perfectly matches the level of your journal.

Arsen Dzhanoev

ISSN (Print Edition): 2429-5299
ISSN (Electronic Edition): 2725-3090

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